draft-ietf-quic-transport-10.txt   draft-ietf-quic-transport-11.txt 
QUIC J. Iyengar, Ed. QUIC J. Iyengar, Ed.
Internet-Draft Fastly Internet-Draft Fastly
Intended status: Standards Track M. Thomson, Ed. Intended status: Standards Track M. Thomson, Ed.
Expires: September 6, 2018 Mozilla Expires: October 19, 2018 Mozilla
March 05, 2018 April 17, 2018
QUIC: A UDP-Based Multiplexed and Secure Transport QUIC: A UDP-Based Multiplexed and Secure Transport
draft-ietf-quic-transport-10 draft-ietf-quic-transport-11
Abstract Abstract
This document defines the core of the QUIC transport protocol. This This document defines the core of the QUIC transport protocol. This
document describes connection establishment, packet format, document describes connection establishment, packet format,
multiplexing and reliability. Accompanying documents describe the multiplexing and reliability. Accompanying documents describe the
cryptographic handshake and loss detection. cryptographic handshake and loss detection.
Note to Readers Note to Readers
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 5 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 6
2.1. Notational Conventions . . . . . . . . . . . . . . . . . 6 2.1. Notational Conventions . . . . . . . . . . . . . . . . . 6
3. A QUIC Overview . . . . . . . . . . . . . . . . . . . . . . . 6 3. Versions . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Low-Latency Connection Establishment . . . . . . . . . . 7 4. Packet Types and Formats . . . . . . . . . . . . . . . . . . 8
3.2. Stream Multiplexing . . . . . . . . . . . . . . . . . . . 7 4.1. Long Header . . . . . . . . . . . . . . . . . . . . . . . 8
3.3. Rich Signaling for Congestion Control and Loss Recovery . 7 4.2. Short Header . . . . . . . . . . . . . . . . . . . . . . 10
3.4. Stream and Connection Flow Control . . . . . . . . . . . 7 4.3. Version Negotiation Packet . . . . . . . . . . . . . . . 12
3.5. Authenticated and Encrypted Header and Payload . . . . . 8 4.4. Cryptographic Handshake Packets . . . . . . . . . . . . . 14
3.6. Connection Migration and Resilience to NAT Rebinding . . 8 4.4.1. Initial Packet . . . . . . . . . . . . . . . . . . . 14
3.7. Version Negotiation . . . . . . . . . . . . . . . . . . . 9 4.4.2. Retry Packet . . . . . . . . . . . . . . . . . . . . 15
4. Versions . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.4.3. Handshake Packet . . . . . . . . . . . . . . . . . . 16
5. Packet Types and Formats . . . . . . . . . . . . . . . . . . 10 4.5. Protected Packets . . . . . . . . . . . . . . . . . . . . 17
5.1. Long Header . . . . . . . . . . . . . . . . . . . . . . . 10 4.6. Coaslescing Packets . . . . . . . . . . . . . . . . . . . 17
5.2. Short Header . . . . . . . . . . . . . . . . . . . . . . 12 4.7. Connection ID . . . . . . . . . . . . . . . . . . . . . . 18
5.3. Version Negotiation Packet . . . . . . . . . . . . . . . 13 4.8. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 19
5.4. Cryptographic Handshake Packets . . . . . . . . . . . . . 14 4.8.1. Initial Packet Number . . . . . . . . . . . . . . . . 20
5.4.1. Initial Packet . . . . . . . . . . . . . . . . . . . 15 5. Frames and Frame Types . . . . . . . . . . . . . . . . . . . 20
5.4.2. Retry Packet . . . . . . . . . . . . . . . . . . . . 15 6. Life of a Connection . . . . . . . . . . . . . . . . . . . . 22
5.4.3. Handshake Packet . . . . . . . . . . . . . . . . . . 16 6.1. Matching Packets to Connections . . . . . . . . . . . . . 23
5.5. Protected Packets . . . . . . . . . . . . . . . . . . . . 17 6.1.1. Client Packet Handling . . . . . . . . . . . . . . . 23
5.6. Connection ID . . . . . . . . . . . . . . . . . . . . . . 17 6.1.2. Server Packet Handling . . . . . . . . . . . . . . . 23
5.7. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 18 6.2. Version Negotiation . . . . . . . . . . . . . . . . . . . 24
5.7.1. Initial Packet Number . . . . . . . . . . . . . . . . 19 6.2.1. Sending Version Negotiation Packets . . . . . . . . . 25
6. Frames and Frame Types . . . . . . . . . . . . . . . . . . . 19 6.2.2. Handling Version Negotiation Packets . . . . . . . . 25
7. Life of a Connection . . . . . . . . . . . . . . . . . . . . 21 6.2.3. Using Reserved Versions . . . . . . . . . . . . . . . 26
7.1. Matching Packets to Connections . . . . . . . . . . . . . 22 6.3. Cryptographic and Transport Handshake . . . . . . . . . . 26
7.1.1. Client Packet Handling . . . . . . . . . . . . . . . 22 6.4. Transport Parameters . . . . . . . . . . . . . . . . . . 27
7.1.2. Server Packet Handling . . . . . . . . . . . . . . . 22 6.4.1. Transport Parameter Definitions . . . . . . . . . . . 29
7.2. Version Negotiation . . . . . . . . . . . . . . . . . . . 23 6.4.2. Values of Transport Parameters for 0-RTT . . . . . . 30
7.2.1. Sending Version Negotiation Packets . . . . . . . . . 23 6.4.3. New Transport Parameters . . . . . . . . . . . . . . 31
7.2.2. Handling Version Negotiation Packets . . . . . . . . 24 6.4.4. Version Negotiation Validation . . . . . . . . . . . 31
7.2.3. Using Reserved Versions . . . . . . . . . . . . . . . 24 6.5. Stateless Retries . . . . . . . . . . . . . . . . . . . . 33
7.3. Cryptographic and Transport Handshake . . . . . . . . . . 25 6.6. Proof of Source Address Ownership . . . . . . . . . . . . 33
7.4. Transport Parameters . . . . . . . . . . . . . . . . . . 26 6.6.1. Client Address Validation Procedure . . . . . . . . . 34
7.4.1. Transport Parameter Definitions . . . . . . . . . . . 28 6.6.2. Address Validation on Session Resumption . . . . . . 35
7.4.2. Values of Transport Parameters for 0-RTT . . . . . . 30 6.6.3. Address Validation Token Integrity . . . . . . . . . 35
7.4.3. New Transport Parameters . . . . . . . . . . . . . . 30 6.7. Path Validation . . . . . . . . . . . . . . . . . . . . . 36
7.4.4. Version Negotiation Validation . . . . . . . . . . . 31 6.7.1. Initiation . . . . . . . . . . . . . . . . . . . . . 36
7.5. Stateless Retries . . . . . . . . . . . . . . . . . . . . 32 6.7.2. Response . . . . . . . . . . . . . . . . . . . . . . 37
7.6. Proof of Source Address Ownership . . . . . . . . . . . . 33 6.7.3. Completion . . . . . . . . . . . . . . . . . . . . . 37
7.6.1. Client Address Validation Procedure . . . . . . . . . 33 6.7.4. Abandonment . . . . . . . . . . . . . . . . . . . . . 38
7.6.2. Address Validation on Session Resumption . . . . . . 34 6.8. Connection Migration . . . . . . . . . . . . . . . . . . 38
7.6.3. Address Validation Token Integrity . . . . . . . . . 35 6.8.1. Probing a New Path . . . . . . . . . . . . . . . . . 38
7.7. Connection Migration . . . . . . . . . . . . . . . . . . 35 6.8.2. Initiating Connection Migration . . . . . . . . . . . 39
7.7.1. Privacy Implications of Connection Migration . . . . 36 6.8.3. Responding to Connection Migration . . . . . . . . . 39
7.7.2. Address Validation for Migrated Connections . . . . . 37 6.8.4. Loss Detection and Congestion Control . . . . . . . . 41
7.8. Spurious Connection Migrations . . . . . . . . . . . . . 39 6.8.5. Privacy Implications of Connection Migration . . . . 42
7.9. Connection Termination . . . . . . . . . . . . . . . . . 40 6.9. Connection Termination . . . . . . . . . . . . . . . . . 43
7.9.1. Closing and Draining Connection States . . . . . . . 40 6.9.1. Closing and Draining Connection States . . . . . . . 44
7.9.2. Idle Timeout . . . . . . . . . . . . . . . . . . . . 41 6.9.2. Idle Timeout . . . . . . . . . . . . . . . . . . . . 45
7.9.3. Immediate Close . . . . . . . . . . . . . . . . . . . 41 6.9.3. Immediate Close . . . . . . . . . . . . . . . . . . . 45
7.9.4. Stateless Reset . . . . . . . . . . . . . . . . . . . 42 6.9.4. Stateless Reset . . . . . . . . . . . . . . . . . . . 46
8. Frame Types and Formats . . . . . . . . . . . . . . . . . . . 45 7. Frame Types and Formats . . . . . . . . . . . . . . . . . . . 49
8.1. Variable-Length Integer Encoding . . . . . . . . . . . . 45 7.1. Variable-Length Integer Encoding . . . . . . . . . . . . 49
8.2. PADDING Frame . . . . . . . . . . . . . . . . . . . . . . 46 7.2. PADDING Frame . . . . . . . . . . . . . . . . . . . . . . 50
8.3. RST_STREAM Frame . . . . . . . . . . . . . . . . . . . . 46 7.3. RST_STREAM Frame . . . . . . . . . . . . . . . . . . . . 50
8.4. CONNECTION_CLOSE frame . . . . . . . . . . . . . . . . . 47 7.4. CONNECTION_CLOSE frame . . . . . . . . . . . . . . . . . 51
8.5. APPLICATION_CLOSE frame . . . . . . . . . . . . . . . . . 48 7.5. APPLICATION_CLOSE frame . . . . . . . . . . . . . . . . . 52
8.6. MAX_DATA Frame . . . . . . . . . . . . . . . . . . . . . 48 7.6. MAX_DATA Frame . . . . . . . . . . . . . . . . . . . . . 52
8.7. MAX_STREAM_DATA Frame . . . . . . . . . . . . . . . . . . 49 7.7. MAX_STREAM_DATA Frame . . . . . . . . . . . . . . . . . . 53
8.8. MAX_STREAM_ID Frame . . . . . . . . . . . . . . . . . . . 50 7.8. MAX_STREAM_ID Frame . . . . . . . . . . . . . . . . . . . 54
8.9. PING Frame . . . . . . . . . . . . . . . . . . . . . . . 50 7.9. PING Frame . . . . . . . . . . . . . . . . . . . . . . . 54
8.10. BLOCKED Frame . . . . . . . . . . . . . . . . . . . . . . 51 7.10. BLOCKED Frame . . . . . . . . . . . . . . . . . . . . . . 55
8.11. STREAM_BLOCKED Frame . . . . . . . . . . . . . . . . . . 51 7.11. STREAM_BLOCKED Frame . . . . . . . . . . . . . . . . . . 55
8.12. STREAM_ID_BLOCKED Frame . . . . . . . . . . . . . . . . . 52 7.12. STREAM_ID_BLOCKED Frame . . . . . . . . . . . . . . . . . 56
8.13. NEW_CONNECTION_ID Frame . . . . . . . . . . . . . . . . . 52 7.13. NEW_CONNECTION_ID Frame . . . . . . . . . . . . . . . . . 56
8.14. STOP_SENDING Frame . . . . . . . . . . . . . . . . . . . 53 7.14. STOP_SENDING Frame . . . . . . . . . . . . . . . . . . . 58
8.15. ACK Frame . . . . . . . . . . . . . . . . . . . . . . . . 54 7.15. ACK Frame . . . . . . . . . . . . . . . . . . . . . . . . 58
8.15.1. ACK Block Section . . . . . . . . . . . . . . . . . 55 7.15.1. ACK Block Section . . . . . . . . . . . . . . . . . 60
8.15.2. Sending ACK Frames . . . . . . . . . . . . . . . . . 57 7.15.2. Sending ACK Frames . . . . . . . . . . . . . . . . . 61
8.15.3. ACK Frames and Packet Protection . . . . . . . . . . 58 7.15.3. ACK Frames and Packet Protection . . . . . . . . . . 62
8.16. PATH_CHALLENGE Frame . . . . . . . . . . . . . . . . . . 59 7.16. PATH_CHALLENGE Frame . . . . . . . . . . . . . . . . . . 63
8.17. PATH_RESPONSE Frame . . . . . . . . . . . . . . . . . . . 59 7.17. PATH_RESPONSE Frame . . . . . . . . . . . . . . . . . . . 63
8.18. STREAM Frames . . . . . . . . . . . . . . . . . . . . . . 60 7.18. STREAM Frames . . . . . . . . . . . . . . . . . . . . . . 64
9. Packetization and Reliability . . . . . . . . . . . . . . . . 61 8. Packetization and Reliability . . . . . . . . . . . . . . . . 65
9.1. Packet Processing and Acknowledgment . . . . . . . . . . 62 8.1. Packet Processing and Acknowledgment . . . . . . . . . . 66
9.2. Retransmission of Information . . . . . . . . . . . . . . 62 8.2. Retransmission of Information . . . . . . . . . . . . . . 66
9.3. Packet Size . . . . . . . . . . . . . . . . . . . . . . . 64 8.3. Packet Size . . . . . . . . . . . . . . . . . . . . . . . 68
9.4. Path Maximum Transmission Unit . . . . . . . . . . . . . 64 8.4. Path Maximum Transmission Unit . . . . . . . . . . . . . 68
9.4.1. Special Considerations for PMTU Discovery . . . . . . 65 8.4.1. Special Considerations for PMTU Discovery . . . . . . 69
9.4.2. Special Considerations for Packetization Layer PMTU 8.4.2. Special Considerations for Packetization Layer PMTU
Discovery . . . . . . . . . . . . . . . . . . . . . . 66 Discovery . . . . . . . . . . . . . . . . . . . . . . 70
10. Streams: QUIC's Data Structuring Abstraction . . . . . . . . 66 9. Streams: QUIC's Data Structuring Abstraction . . . . . . . . 70
10.1. Stream Identifiers . . . . . . . . . . . . . . . . . . . 67 9.1. Stream Identifiers . . . . . . . . . . . . . . . . . . . 71
10.2. Stream States . . . . . . . . . . . . . . . . . . . . . 68 9.2. Stream States . . . . . . . . . . . . . . . . . . . . . . 72
10.2.1. Send Stream States . . . . . . . . . . . . . . . . . 69 9.2.1. Send Stream States . . . . . . . . . . . . . . . . . 73
10.2.2. Receive Stream States . . . . . . . . . . . . . . . 71 9.2.2. Receive Stream States . . . . . . . . . . . . . . . . 75
10.2.3. Permitted Frame Types . . . . . . . . . . . . . . . 74 9.2.3. Permitted Frame Types . . . . . . . . . . . . . . . . 77
10.2.4. Bidirectional Stream States . . . . . . . . . . . . 74 9.2.4. Bidirectional Stream States . . . . . . . . . . . . . 77
10.3. Solicited State Transitions . . . . . . . . . . . . . . 75 9.3. Solicited State Transitions . . . . . . . . . . . . . . . 78
10.4. Stream Concurrency . . . . . . . . . . . . . . . . . . . 76 9.4. Stream Concurrency . . . . . . . . . . . . . . . . . . . 79
10.5. Sending and Receiving Data . . . . . . . . . . . . . . . 77 9.5. Sending and Receiving Data . . . . . . . . . . . . . . . 80
10.6. Stream Prioritization . . . . . . . . . . . . . . . . . 77 9.6. Stream Prioritization . . . . . . . . . . . . . . . . . . 80
11. Flow Control . . . . . . . . . . . . . . . . . . . . . . . . 78 10. Flow Control . . . . . . . . . . . . . . . . . . . . . . . . 81
11.1. Edge Cases and Other Considerations . . . . . . . . . . 79 10.1. Edge Cases and Other Considerations . . . . . . . . . . 83
11.1.1. Response to a RST_STREAM . . . . . . . . . . . . . . 80 10.1.1. Response to a RST_STREAM . . . . . . . . . . . . . . 83
11.1.2. Data Limit Increments . . . . . . . . . . . . . . . 80 10.1.2. Data Limit Increments . . . . . . . . . . . . . . . 83
11.1.3. Handshake Exemption . . . . . . . . . . . . . . . . 81 10.1.3. Handshake Exemption . . . . . . . . . . . . . . . . 84
11.2. Stream Limit Increment . . . . . . . . . . . . . . . . . 81 10.2. Stream Limit Increment . . . . . . . . . . . . . . . . . 84
11.2.1. Blocking on Flow Control . . . . . . . . . . . . . . 81 10.2.1. Blocking on Flow Control . . . . . . . . . . . . . . 84
11.3. Stream Final Offset . . . . . . . . . . . . . . . . . . 82 10.3. Stream Final Offset . . . . . . . . . . . . . . . . . . 85
12. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 82 11. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 85
12.1. Connection Errors . . . . . . . . . . . . . . . . . . . 83 11.1. Connection Errors . . . . . . . . . . . . . . . . . . . 86
12.2. Stream Errors . . . . . . . . . . . . . . . . . . . . . 83 11.2. Stream Errors . . . . . . . . . . . . . . . . . . . . . 87
12.3. Transport Error Codes . . . . . . . . . . . . . . . . . 84 11.3. Transport Error Codes . . . . . . . . . . . . . . . . . 87
12.4. Application Protocol Error Codes . . . . . . . . . . . . 85 11.4. Application Protocol Error Codes . . . . . . . . . . . . 88
13. Security and Privacy Considerations . . . . . . . . . . . . . 85 12. Security and Privacy Considerations . . . . . . . . . . . . . 89
13.1. Spoofed ACK Attack . . . . . . . . . . . . . . . . . . . 86 12.1. Spoofed ACK Attack . . . . . . . . . . . . . . . . . . . 89
13.2. Slowloris Attacks . . . . . . . . . . . . . . . . . . . 86 12.2. Optimistic ACK Attack . . . . . . . . . . . . . . . . . 89
13.3. Stream Fragmentation and Reassembly Attacks . . . . . . 87 12.3. Slowloris Attacks . . . . . . . . . . . . . . . . . . . 90
13.4. Stream Commitment Attack . . . . . . . . . . . . . . . . 87 12.4. Stream Fragmentation and Reassembly Attacks . . . . . . 90
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 87 12.5. Stream Commitment Attack . . . . . . . . . . . . . . . . 90
14.1. QUIC Transport Parameter Registry . . . . . . . . . . . 87 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 91
14.2. QUIC Transport Error Codes Registry . . . . . . . . . . 89 13.1. QUIC Transport Parameter Registry . . . . . . . . . . . 91
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 90 13.2. QUIC Transport Error Codes Registry . . . . . . . . . . 92
15.1. Normative References . . . . . . . . . . . . . . . . . . 90 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 94
15.2. Informative References . . . . . . . . . . . . . . . . . 92 14.1. Normative References . . . . . . . . . . . . . . . . . . 94
15.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 93 14.2. Informative References . . . . . . . . . . . . . . . . . 95
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 93 14.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 93 Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 96
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 93 Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 97
C.1. Since draft-ietf-quic-transport-09 . . . . . . . . . . . 94 Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 97
C.2. Since draft-ietf-quic-transport-08 . . . . . . . . . . . 94 C.1. Since draft-ietf-quic-transport-10 . . . . . . . . . . . 97
C.3. Since draft-ietf-quic-transport-07 . . . . . . . . . . . 95 C.2. Since draft-ietf-quic-transport-09 . . . . . . . . . . . 98
C.4. Since draft-ietf-quic-transport-06 . . . . . . . . . . . 96 C.3. Since draft-ietf-quic-transport-08 . . . . . . . . . . . 98
C.5. Since draft-ietf-quic-transport-05 . . . . . . . . . . . 96 C.4. Since draft-ietf-quic-transport-07 . . . . . . . . . . . 99
C.6. Since draft-ietf-quic-transport-04 . . . . . . . . . . . 96 C.5. Since draft-ietf-quic-transport-06 . . . . . . . . . . . 100
C.7. Since draft-ietf-quic-transport-03 . . . . . . . . . . . 97 C.6. Since draft-ietf-quic-transport-05 . . . . . . . . . . . 100
C.8. Since draft-ietf-quic-transport-02 . . . . . . . . . . . 97 C.7. Since draft-ietf-quic-transport-04 . . . . . . . . . . . 100
C.9. Since draft-ietf-quic-transport-01 . . . . . . . . . . . 98 C.8. Since draft-ietf-quic-transport-03 . . . . . . . . . . . 101
C.10. Since draft-ietf-quic-transport-00 . . . . . . . . . . . 100 C.9. Since draft-ietf-quic-transport-02 . . . . . . . . . . . 101
C.11. Since draft-hamilton-quic-transport-protocol-01 . . . . . 100 C.10. Since draft-ietf-quic-transport-01 . . . . . . . . . . . 102
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 100 C.11. Since draft-ietf-quic-transport-00 . . . . . . . . . . . 104
C.12. Since draft-hamilton-quic-transport-protocol-01 . . . . . 104
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 105
1. Introduction 1. Introduction
QUIC is a multiplexed and secure transport protocol that runs on top QUIC is a multiplexed and secure transport protocol that runs on top
of UDP. QUIC aims to provide a flexible set of features that allow of UDP. QUIC aims to provide a flexible set of features that allow
it to be a general-purpose transport for multiple applications. it to be a general-purpose secure transport for multiple
applications.
o Version negotiation
o Low-latency connection establishment
o Authenticated and encrypted header and payload
o Stream multiplexing
o Stream and connection-level flow control
o Connection migration and resilience to NAT rebinding
QUIC implements techniques learned from experience with TCP, SCTP and QUIC implements techniques learned from experience with TCP, SCTP and
other transport protocols. QUIC uses UDP as substrate so as to not other transport protocols. QUIC uses UDP as substrate so as to not
require changes to legacy client operating systems and middleboxes to require changes to legacy client operating systems and middleboxes to
be deployable. QUIC authenticates all of its headers and encrypts be deployable. QUIC authenticates all of its headers and encrypts
most of the data it exchanges, including its signaling. This allows most of the data it exchanges, including its signaling. This allows
the protocol to evolve without incurring a dependency on upgrades to the protocol to evolve without incurring a dependency on upgrades to
middleboxes. This document describes the core QUIC protocol, middleboxes. This document describes the core QUIC protocol,
including the conceptual design, wire format, and mechanisms of the including the conceptual design, wire format, and mechanisms of the
QUIC protocol for connection establishment, stream multiplexing, QUIC protocol for connection establishment, stream multiplexing,
stream and connection-level flow control, and data reliability. stream and connection-level flow control, connection migration, and
data reliability.
Accompanying documents describe QUIC's loss detection and congestion Accompanying documents describe QUIC's loss detection and congestion
control [QUIC-RECOVERY], and the use of TLS 1.3 for key negotiation control [QUIC-RECOVERY], and the use of TLS 1.3 for key negotiation
[QUIC-TLS]. [QUIC-TLS].
QUIC version 1 conforms to the protocol invariants in QUIC version 1 conforms to the protocol invariants in
[QUIC-INVARIANTS]. [QUIC-INVARIANTS].
2. Conventions and Definitions 2. Conventions and Definitions
skipping to change at page 6, line 11 skipping to change at page 6, line 27
Server: The endpoint accepting incoming QUIC connections. Server: The endpoint accepting incoming QUIC connections.
Endpoint: The client or server end of a connection. Endpoint: The client or server end of a connection.
Stream: A logical, bi-directional channel of ordered bytes within a Stream: A logical, bi-directional channel of ordered bytes within a
QUIC connection. QUIC connection.
Connection: A conversation between two QUIC endpoints with a single Connection: A conversation between two QUIC endpoints with a single
encryption context that multiplexes streams within it. encryption context that multiplexes streams within it.
Connection ID: The 64-bit unsigned number used as an identifier for Connection ID: An opaque identifier that is used to identify a QUIC
a QUIC connection. connection at an endpoint. Each endpoint sets a value that its
peer includes in packets.
QUIC packet: A well-formed UDP payload that can be parsed by a QUIC QUIC packet: A well-formed UDP payload that can be parsed by a QUIC
receiver. receiver.
QUIC is a name, not an acronym.
2.1. Notational Conventions 2.1. Notational Conventions
Packet and frame diagrams use the format described in Section 3.1 of Packet and frame diagrams use the format described in Section 3.1 of
[RFC2360], with the following additional conventions: [RFC2360], with the following additional conventions:
[x] Indicates that x is optional [x] Indicates that x is optional
x (A) Indicates that x is A bits long x (A) Indicates that x is A bits long
x (A/B/C) ... Indicates that x is one of A, B, or C bits long x (A/B/C) ... Indicates that x is one of A, B, or C bits long
x (i) ... Indicates that x uses the variable-length encoding in x (i) ... Indicates that x uses the variable-length encoding in
Section 8.1 Section 7.1
x (*) ... Indicates that x is variable-length x (*) ... Indicates that x is variable-length
3. A QUIC Overview 3. Versions
This section briefly describes QUIC's key mechanisms and benefits.
Key strengths of QUIC include:
o Low-latency connection establishment
o Multiplexing without head-of-line blocking
o Authenticated and encrypted header and payload
o Rich signaling for congestion control and loss recovery
o Stream and connection flow control
o Connection migration and resilience to NAT rebinding
o Version negotiation
3.1. Low-Latency Connection Establishment
QUIC relies on a combined cryptographic and transport handshake for
setting up a secure transport connection. QUIC connections are
expected to commonly use 0-RTT handshakes, meaning that for most QUIC
connections, data can be sent immediately following the client
handshake packet, without waiting for a reply from the server. QUIC
provides a dedicated stream (Stream ID 0) to be used for performing
the cryptographic handshake and QUIC options negotiation. The format
of the QUIC options and parameters used during negotiation are
described in this document, but the handshake protocol that runs on
Stream ID 0 is described in the accompanying cryptographic handshake
draft [QUIC-TLS].
3.2. Stream Multiplexing
When application messages are transported over TCP, independent
application messages can suffer from head-of-line blocking. When an
application multiplexes many streams atop TCP's single-bytestream
abstraction, a loss of a TCP segment results in blocking of all
subsequent segments until a retransmission arrives, irrespective of
the application streams that are encapsulated in subsequent segments.
QUIC ensures that lost packets carrying data for an individual stream
only impact that specific stream. Data received on other streams can
continue to be reassembled and delivered to the application.
3.3. Rich Signaling for Congestion Control and Loss Recovery
QUIC's packet framing and acknowledgments carry rich information that
help both congestion control and loss recovery in fundamental ways.
Each QUIC packet carries a new packet number, including those
carrying retransmitted data. This obviates the need for a separate
mechanism to distinguish acknowledgments for retransmissions from
those for original transmissions, avoiding TCP's retransmission
ambiguity problem. QUIC acknowledgments also explicitly encode the
delay between the receipt of a packet and its acknowledgment being
sent, and together with the monotonically-increasing packet numbers,
this allows for precise network roundtrip-time (RTT) calculation.
QUIC's ACK frames support multiple ACK blocks, so QUIC is more
resilient to reordering than TCP with SACK support, as well as able
to keep more bytes on the wire when there is reordering or loss.
3.4. Stream and Connection Flow Control
QUIC implements stream- and connection-level flow control. At a high
level, a QUIC receiver advertises the maximum amount of data that it
is willing to receive on each stream. As data is sent, received, and
delivered on a particular stream, the receiver sends MAX_STREAM_DATA
frames that increase the advertised limit for that stream, allowing
the peer to send more data on that stream.
In addition to this stream-level flow control, QUIC implements
connection-level flow control to limit the aggregate buffer that a
QUIC receiver is willing to allocate to all streams on a connection.
Connection-level flow control works in the same way as stream-level
flow control, but the bytes delivered and the limits are aggregated
across all streams.
3.5. Authenticated and Encrypted Header and Payload
TCP headers appear in plaintext on the wire and are not
authenticated, causing a plethora of injection and header
manipulation issues for TCP, such as receive-window manipulation and
sequence-number overwriting. While some of these are mechanisms used
by middleboxes to improve TCP performance, others are active attacks.
Even "performance-enhancing" middleboxes that routinely interpose on
the transport state machine end up limiting the evolvability of the
transport protocol, as has been observed in the design of MPTCP
[RFC6824] and in its subsequent deployability issues.
Generally, QUIC packets are always authenticated and the payload is
typically fully encrypted. The parts of the packet header which are
not encrypted are still authenticated by the receiver, so as to
thwart any packet injection or manipulation by third parties. Some
early handshake packets, such as the Version Negotiation packet, are
not encrypted, but information sent in these unencrypted handshake
packets is later verified as part of cryptographic processing.
3.6. Connection Migration and Resilience to NAT Rebinding
QUIC connections are identified by a Connection ID, a 64-bit unsigned
number randomly generated by the server. QUIC's consistent
connection ID allows connections to survive changes to the client's
IP and port, such as those caused by NAT rebindings or by the client
changing network connectivity to a new address. QUIC provides
automatic cryptographic verification of a rebound client, since the
client continues to use the same session key for encrypting and
decrypting packets. The consistent connection ID can be used to
allow migration of the connection to a new server IP address as well,
since the Connection ID remains consistent across changes in the
client's and the server's network addresses.
3.7. Version Negotiation
QUIC version negotiation allows for multiple versions of the protocol
to be deployed and used concurrently. Version negotiation is
described in Section 7.2.
4. Versions
QUIC versions are identified using a 32-bit unsigned number. QUIC versions are identified using a 32-bit unsigned number.
The version 0x00000000 is reserved to represent version negotiation. The version 0x00000000 is reserved to represent version negotiation.
This version of the specification is identified by the number This version of the specification is identified by the number
0x00000001. 0x00000001.
Other versions of QUIC might have different properties to this Other versions of QUIC might have different properties to this
version. The properties of QUIC that are guaranteed to be consistent version. The properties of QUIC that are guaranteed to be consistent
across all versions of the protocol are described in across all versions of the protocol are described in
skipping to change at page 10, line 8 skipping to change at page 8, line 5
(0x00000001), is reserved for the version of the protocol that is (0x00000001), is reserved for the version of the protocol that is
published as an RFC. published as an RFC.
Version numbers used to identify IETF drafts are created by adding Version numbers used to identify IETF drafts are created by adding
the draft number to 0xff000000. For example, draft-ietf-quic- the draft number to 0xff000000. For example, draft-ietf-quic-
transport-13 would be identified as 0xff00000D. transport-13 would be identified as 0xff00000D.
Implementors are encouraged to register version numbers of QUIC that Implementors are encouraged to register version numbers of QUIC that
they are using for private experimentation on the github wiki [4]. they are using for private experimentation on the github wiki [4].
5. Packet Types and Formats 4. Packet Types and Formats
We first describe QUIC's packet types and their formats, since some We first describe QUIC's packet types and their formats, since some
are referenced in subsequent mechanisms. are referenced in subsequent mechanisms.
All numeric values are encoded in network byte order (that is, big- All numeric values are encoded in network byte order (that is, big-
endian) and all field sizes are in bits. When discussing individual endian) and all field sizes are in bits. When discussing individual
bits of fields, the least significant bit is referred to as bit 0. bits of fields, the least significant bit is referred to as bit 0.
Hexadecimal notation is used for describing the value of fields. Hexadecimal notation is used for describing the value of fields.
Any QUIC packet has either a long or a short header, as indicated by Any QUIC packet has either a long or a short header, as indicated by
the Header Form bit. Long headers are expected to be used early in the Header Form bit. Long headers are expected to be used early in
the connection before version negotiation and establishment of 1-RTT the connection before version negotiation and establishment of 1-RTT
keys. Short headers are minimal version-specific headers, which are keys. Short headers are minimal version-specific headers, which are
used after version negotiation and 1-RTT keys are established. used after version negotiation and 1-RTT keys are established.
5.1. Long Header 4.1. Long Header
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|1| Type (7) | |1| Type (7) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Connection ID (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version (32) | | Version (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|DCIL(4)|SCIL(4)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Connection ID (0/32..144) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Connection ID (0/32..144) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Length (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packet Number (32) | | Packet Number (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload (*) ... | Payload (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Long Header Format Figure 1: Long Header Format
Long headers are used for packets that are sent prior to the Long headers are used for packets that are sent prior to the
completion of version negotiation and establishment of 1-RTT keys. completion of version negotiation and establishment of 1-RTT keys.
Once both conditions are met, a sender switches to sending packets Once both conditions are met, a sender switches to sending packets
using the short header (Section 5.2). The long form allows for using the short header (Section 4.2). The long form allows for
special packets - such as the Version Negotiation packet - to be special packets - such as the Version Negotiation packet - to be
represented in this uniform fixed-length packet format. A long represented in this uniform fixed-length packet format. A long
header contains the following fields: header contains the following fields:
Header Form: The most significant bit (0x80) of octet 0 (the first Header Form: The most significant bit (0x80) of octet 0 (the first
octet) is set to 1 for long headers. octet) is set to 1 for long headers.
Long Packet Type: The remaining seven bits of octet 0 contain the Long Packet Type: The remaining seven bits of octet 0 contain the
packet type. This field can indicate one of 128 packet types. packet type. This field can indicate one of 128 packet types.
The types specified for this version are listed in Table 1. The types specified for this version are listed in Table 1.
Connection ID: Octets 1 through 8 contain the connection ID. Version: The QUIC Version is a 32-bit field that follows the Type.
Section 5.6 describes the use of this field in more detail. This field indicates which version of QUIC is in use and
determines how the rest of the protocol fields are interpreted.
Version: Octets 9 to 12 contain the selected protocol version. This DCIL and SCIL: Octet 1 contains the lengths of the two connection ID
field indicates which version of QUIC is in use and determines how fields that follow it. These lengths are encoded as two 4-bit
the rest of the protocol fields are interpreted. unsigned integers. The Destination Connection ID Length (DCIL)
field occupies the 4 high bits of the octet and the Source
Connection ID Length (SCIL) field occupies the 4 low bits of the
octet. An encoded length of 0 indicates that the connection ID is
also 0 octets in length. Non-zero encoded lengths are increased
by 3 to get the full length of the connection ID, producing a
length between 4 and 18 octets inclusive. For example, an octet
with the value 0x50 describes an 8-octet Destination Connection ID
and a zero-length Source Connection ID.
Packet Number: Octets 13 to 16 contain the packet number. Destination Connection ID: The Destination Connection ID field
Section 5.7 describes the use of packet numbers. follows the connection ID lengths and is either 0 octets in length
or between 4 and 18 octets. Section 4.7 describes the use of this
field in more detail.
Payload: Octets from 17 onwards (the rest of QUIC packet) are the Source Connection ID: The Source Connection ID field follows the
payload of the packet. Destination Connection ID and is either 0 octets in length or
between 4 and 18 octets. Section 4.7 describes the use of this
field in more detail.
Payload Length: The length of the Payload field in octets, encoded
as a variable-length integer (Section 7.1).
Packet Number: The Packet Number is a 32-bit field that follows the
two connection IDs. Section 4.8 describes the use of packet
numbers.
Payload: The payload of the packet.
The following packet types are defined: The following packet types are defined:
+------+-----------------+---------------+ +------+-----------------+---------------+
| Type | Name | Section | | Type | Name | Section |
+------+-----------------+---------------+ +------+-----------------+---------------+
| 0x7F | Initial | Section 5.4.1 | | 0x7F | Initial | Section 4.4.1 |
| | | | | | | |
| 0x7E | Retry | Section 5.4.2 | | 0x7E | Retry | Section 4.4.2 |
| | | | | | | |
| 0x7D | Handshake | Section 5.4.3 | | 0x7D | Handshake | Section 4.4.3 |
| | | | | | | |
| 0x7C | 0-RTT Protected | Section 5.5 | | 0x7C | 0-RTT Protected | Section 4.5 |
+------+-----------------+---------------+ +------+-----------------+---------------+
Table 1: Long Header Packet Types Table 1: Long Header Packet Types
The header form, packet type, connection ID, packet number and The header form, type, connection ID lengths octet, destination and
version fields of a long header packet are version-independent. The source connection IDs, and version fields of a long header packet are
types of packets defined in Table 1 are version-specific. See version-independent. The packet number and values for packet types
[QUIC-INVARIANTS] for details on how packets from different versions defined in Table 1 are version-specific. See [QUIC-INVARIANTS] for
of QUIC are interpreted. details on how packets from different versions of QUIC are
interpreted.
The interpretation of the fields and the payload are specific to a The interpretation of the fields and the payload are specific to a
version and packet type. Type-specific semantics for this version version and packet type. Type-specific semantics for this version
are described in the following sections. are described in the following sections.
5.2. Short Header End of the Payload field (which is also the end of the long header
packet) is determined by the value of the Payload Length field.
Senders can coalesce multiple long header packets into one UDP
datagram. See Section 4.6 for more details.
4.2. Short Header
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|0|C|K|1|0|T T T| |0|K|1|1|0|R|T T|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | Destination Connection ID (0..144) ...
+ [Connection ID (64)] +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packet Number (8/16/32) ... | Packet Number (8/16/32) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protected Payload (*) ... | Protected Payload (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Short Header Format Figure 2: Short Header Format
The short header can be used after the version and 1-RTT keys are The short header can be used after the version and 1-RTT keys are
negotiated. This header form has the following fields: negotiated. This header form has the following fields:
Header Form: The most significant bit (0x80) of octet 0 is set to 0 Header Form: The most significant bit (0x80) of octet 0 is set to 0
for the short header. for the short header.
Omit Connection ID Flag: The second bit (0x40) of octet 0 indicates Key Phase Bit: The second bit (0x40) of octet 0 indicates the key
whether the Connection ID field is omitted. If set to 0, then the
Connection ID field is present; if set to 1, the Connection ID
field is omitted. The Connection ID field can only be omitted if
the omit_connection_id transport parameter (Section 7.4.1) is
specified by the intended recipient of the packet.
Key Phase Bit: The third bit (0x20) of octet 0 indicates the key
phase, which allows a recipient of a packet to identify the packet phase, which allows a recipient of a packet to identify the packet
protection keys that are used to protect the packet. See protection keys that are used to protect the packet. See
[QUIC-TLS] for details. [QUIC-TLS] for details.
[[Editor's Note: this section should be removed and the bit [[Editor's Note: this section should be removed and the bit
definitions changed before this draft goes to the IESG.]] definitions changed before this draft goes to the IESG.]]
Fourth bit: The fourth bit (0x10) of octet 0 is set to 1. Third Bit: The third bit (0x20) of octet 0 is set to 1.
[[Editor's Note: this section should be removed and the bit
definitions changed before this draft goes to the IESG.]]
Fourth Bit: The fourth bit (0x10) of octet 0 is set to 1.
[[Editor's Note: this section should be removed and the bit [[Editor's Note: this section should be removed and the bit
definitions changed before this draft goes to the IESG.]] definitions changed before this draft goes to the IESG.]]
Google QUIC Demultipexing Bit: The fifth bit (0x8) of octet 0 is set Google QUIC Demultipexing Bit: The fifth bit (0x8) of octet 0 is set
to 0. This allows implementations of Google QUIC to distinguish to 0. This allows implementations of Google QUIC to distinguish
Google QUIC packets from short header packets sent by a client Google QUIC packets from short header packets sent by a client
because Google QUIC servers expect the connection ID to always be because Google QUIC servers expect the connection ID to always be
present. The special interpretation of this bit SHOULD be removed present. The special interpretation of this bit SHOULD be removed
from this specification when Google QUIC has finished from this specification when Google QUIC has finished
transitioning to the new header format. transitioning to the new header format.
Short Packet Type: The remaining 3 bits of octet 0 include one of 8 Reserved: The sixth bit (0x4) of octet 0 is reserved for
experimentation.
Short Packet Type: The remaining 2 bits of octet 0 include one of 4
packet types. Table 2 lists the types that are defined for short packet types. Table 2 lists the types that are defined for short
packets. packets.
Connection ID: If the Omit Connection ID Flag is not set, a Destination Connection ID: The Destination Connection ID is a
connection ID occupies octets 1 through 8 of the packet. See connection ID that is chosen by the intended recipient of the
Section 5.6 for more details. packet. See Section 4.7 for more details.
Packet Number: The length of the packet number field depends on the Packet Number: The length of the packet number field depends on the
packet type. This field can be 1, 2 or 4 octets long depending on packet type. This field can be 1, 2 or 4 octets long depending on
the short packet type. the short packet type.
Protected Payload: Packets with a short header always include a Protected Payload: Packets with a short header always include a
1-RTT protected payload. 1-RTT protected payload.
The packet type in a short header currently determines only the size The packet type in a short header currently determines only the size
of the packet number field. Additional types can be used to signal of the packet number field. Additional types can be used to signal
skipping to change at page 13, line 39 skipping to change at page 12, line 21
+------+--------------------+ +------+--------------------+
| 0x0 | 1 octet | | 0x0 | 1 octet |
| | | | | |
| 0x1 | 2 octets | | 0x1 | 2 octets |
| | | | | |
| 0x2 | 4 octets | | 0x2 | 4 octets |
+------+--------------------+ +------+--------------------+
Table 2: Short Header Packet Types Table 2: Short Header Packet Types
The header form, omit connection ID flag, and connection ID of a The header form and connection ID field of a short header packet are
short header packet are version-independent. The remaining fields version-independent. The remaining fields are specific to the
are specific to the selected QUIC version. See [QUIC-INVARIANTS] for selected QUIC version. See [QUIC-INVARIANTS] for details on how
details on how packets from different versions of QUIC are packets from different versions of QUIC are interpreted.
interpreted.
5.3. Version Negotiation Packet 4.3. Version Negotiation Packet
A Version Negotiation packet is inherently not version-specific, and A Version Negotiation packet is inherently not version-specific, and
does not use the packet headers defined above. Upon receipt by a does not use the long packet header (see Section 4.1. Upon receipt
client, it will appear to be a packet using the long header, but will by a client, it will appear to be a packet using the long header, but
be identified as a Version Negotiation packet based on the Version will be identified as a Version Negotiation packet based on the
field. Version field having a value of 0.
The Version Negotiation packet is a response to a client packet that The Version Negotiation packet is a response to a client packet that
contains a version that is not supported by the server, and is only contains a version that is not supported by the server, and is only
sent by servers. sent by servers.
The layout of a Version Negotiation packet is: The layout of a Version Negotiation packet is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|1| Unused (7) | |1| Unused (7) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Connection ID (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version (32) | | Version (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|DCIL(4)|SCIL(4)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Connection ID (0/32..144) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Connection ID (0/32..144) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Supported Version 1 (32) ... | Supported Version 1 (32) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Supported Version 2 (32)] ... | [Supported Version 2 (32)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Supported Version N (32)] ... | [Supported Version N (32)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Version Negotiation Packet Figure 3: Version Negotiation Packet
The value in the Unused field is selected randomly by the server. The value in the Unused field is selected randomly by the server.
The Connection ID field echoes the corresponding value from the
triggering client packet. This allows clients some assurance that The Version field of a Version Negotiation packet MUST be set to
the server received the packet and that the Version Negotiation 0x00000000.
packet is in fact from the server. The Version field MUST be set to
0x00000000. The remainder of the Version Negotiation packet is a The server MUST include the value from the Source Connection ID field
list of 32-bit versions which the server supports. of the packet it receives in the Destination Connection ID field.
The value for Source Connection ID MUST be copied from the
Destination Connection ID of the received packet, which is initially
randomly selected by a client. Echoing both connection IDs gives
clients some assurance that the server received the packet and that
the Version Negotiation packet was not generated by an off-path
attacker.
The remainder of the Version Negotiation packet is a list of 32-bit
versions which the server supports.
A Version Negotiation packet cannot be explicitly acknowledged in an A Version Negotiation packet cannot be explicitly acknowledged in an
ACK frame by a client. Receiving another Initial packet implicitly ACK frame by a client. Receiving another Initial packet implicitly
acknowledges a Version Negotiation packet. acknowledges a Version Negotiation packet.
See Section 7.2 for a description of the version negotiation process. The Version Negotiation packet does not include the Packet Number and
Length fields present in other packets that use the long header form.
5.4. Cryptographic Handshake Packets Consequently, a Version Negotiation packet consumes an entire UDP
datagram.
See Section 6.2 for a description of the version negotiation process.
4.4. Cryptographic Handshake Packets
Once version negotiation is complete, the cryptographic handshake is Once version negotiation is complete, the cryptographic handshake is
used to agree on cryptographic keys. The cryptographic handshake is used to agree on cryptographic keys. The cryptographic handshake is
carried in Initial (Section 5.4.1), Retry (Section 5.4.2) and carried in Initial (Section 4.4.1), Retry (Section 4.4.2) and
Handshake (Section 5.4.3) packets. Handshake (Section 4.4.3) packets.
All these packets use the long header and contain the current QUIC All these packets use the long header and contain the current QUIC
version in the version field. version in the version field.
In order to prevent tampering by version-unaware middleboxes, In order to prevent tampering by version-unaware middleboxes,
handshake packets are protected with a connection- and version- handshake packets are protected with a connection- and version-
specific key, as described in [QUIC-TLS]. This protection does not specific key, as described in [QUIC-TLS]. This protection does not
provide confidentiality or integrity against on-path attackers, but provide confidentiality or integrity against on-path attackers, but
provides some level of protection against off-path attackers. provides some level of protection against off-path attackers.
5.4.1. Initial Packet 4.4.1. Initial Packet
The Initial packet uses long headers with a type value of 0x7F. It The Initial packet uses long headers with a type value of 0x7F. It
carries the first cryptographic handshake message sent by the client. carries the first cryptographic handshake message sent by the client.
The client populates the connection ID field with randomly selected If the client has not previously received a Retry packet from the
values, unless it has received a packet from the server. If the server, it populates the Destination Connection ID field with a
client has received a packet from the server, the connection ID field randomly selected value. This MUST be at least 8 octets in length.
uses the value provided by the server. Until a packet is received from the server, the client MUST use the
same random value unless it also changes the Source Connection ID
(which effectively starts a new connection attempt). The randomized
Destination Connection ID is used to determine packet protection
keys, but is not included in server packets.
If the client received a Retry packet and is sending a second Initial
packet, then it sets the Destination Connection ID to the value from
the Source Connection ID in the Retry packet. Changing Destination
Connection ID also results in a change to the keys used to protect
the Initial packet.
The client populates the Source Connection ID field with a value of
its choosing and sets the low bits of the ConnID Len field to match.
The first Initial packet that is sent by a client contains a The first Initial packet that is sent by a client contains a
randomized packet number. All subsequent packets contain a packet randomized packet number. All subsequent packets contain a packet
number that is incremented by one, see (Section 5.7). number that is incremented by one, see (Section 4.8).
The payload of an Initial packet consists of a STREAM frame (or The payload of an Initial packet conveys a STREAM frame (or frames)
frames) for stream 0 containing a cryptographic handshake message, for stream 0 containing a cryptographic handshake message. The
with enough PADDING frames that the packet is at least 1200 octets stream in this packet always starts at an offset of 0 (see
(see Section 9). The stream in this packet always starts at an Section 6.5) and the complete cryptographic handshake message MUST
offset of 0 (see Section 7.5) and the complete cryptographic fit in a single packet (see Section 6.3).
handshake message MUST fit in a single packet (see Section 7.3).
The payload of a UDP datagram carrying the Initial packet MUST be
expanded to at least 1200 octets (see Section 8), by adding PADDING
frames to the Initial packet and/or by combining the Initial packet
with a 0-RTT packet (see Section 4.6).
The client uses the Initial packet type for any packet that contains The client uses the Initial packet type for any packet that contains
an initial cryptographic handshake message. This includes all cases an initial cryptographic handshake message. This includes all cases
where a new packet containing the initial cryptographic message needs where a new packet containing the initial cryptographic message needs
to be created, this includes the packets sent after receiving a to be created, this includes the packets sent after receiving a
Version Negotiation (Section 5.3) or Retry packet (Section 5.4.2). Version Negotiation (Section 4.3) or Retry packet (Section 4.4.2).
5.4.2. Retry Packet 4.4.2. Retry Packet
A Retry packet uses long headers with a type value of 0x7E. It A Retry packet uses long headers with a type value of 0x7E. It
carries cryptographic handshake messages and acknowledgments. It is carries cryptographic handshake messages and acknowledgments. It is
used by a server that wishes to perform a stateless retry (see used by a server that wishes to perform a stateless retry (see
Section 7.5). Section 6.5).
The server includes a connection ID of its choice in the connection The server populates the Destination Connection ID with the
ID field. The client MUST use this connection ID for any subsequent connection ID that the client included in the Source Connection ID of
packets that it sends. the Initial packet. This might be a zero-length value.
The server includes a connection ID of its choice in the Source
Connection ID field. The client MUST use this connection ID in the
Destination Connection ID of subsequent packets that it sends.
The packet number field echoes the packet number field from the The packet number field echoes the packet number field from the
triggering client packet. triggering client packet.
A Retry packet is never explicitly acknowledged in an ACK frame by a A Retry packet is never explicitly acknowledged in an ACK frame by a
client. Receiving another Initial packet implicitly acknowledges a client. Receiving another Initial packet implicitly acknowledges a
Retry packet. Retry packet.
After receiving a Retry packet, the client uses a new Initial packet After receiving a Retry packet, the client uses a new Initial packet
containing the next cryptographic handshake message. The client containing the next cryptographic handshake message. The client
skipping to change at page 16, line 21 skipping to change at page 16, line 4
After receiving a Retry packet, the client uses a new Initial packet After receiving a Retry packet, the client uses a new Initial packet
containing the next cryptographic handshake message. The client containing the next cryptographic handshake message. The client
retains the state of its cryptographic handshake, but discards all retains the state of its cryptographic handshake, but discards all
transport state. The Initial packet that is generated in response to transport state. The Initial packet that is generated in response to
a Retry packet includes STREAM frames on stream 0 that start again at a Retry packet includes STREAM frames on stream 0 that start again at
an offset of 0. an offset of 0.
Continuing the cryptographic handshake is necessary to ensure that an Continuing the cryptographic handshake is necessary to ensure that an
attacker cannot force a downgrade of any cryptographic parameters. attacker cannot force a downgrade of any cryptographic parameters.
In addition to continuing the cryptographic handshake, the client In addition to continuing the cryptographic handshake, the client
MUST remember the results of any version negotiation that occurred MUST remember the results of any version negotiation that occurred
(see Section 7.2). The client MAY also retain any observed RTT or (see Section 6.2). The client MAY also retain any observed RTT or
congestion state that it has accumulated for the flow, but other congestion state that it has accumulated for the flow, but other
transport state MUST be discarded. transport state MUST be discarded.
The payload of the Retry packet contains a single STREAM frame on The payload of the Retry packet contains at least two frames. It
stream 0 with offset 0 containing the server's cryptographic MUST include a STREAM frame on stream 0 with offset 0 containing the
stateless retry material. It MUST NOT contain any other frames. The server's cryptographic stateless retry material. It MUST also
next STREAM frame sent by the server will also start at stream offset include an ACK frame to acknowledge the client's Initial packet. It
0. MAY additionally include PADDING frames. The next STREAM frame sent
by the server will also start at stream offset 0.
5.4.3. Handshake Packet 4.4.3. Handshake Packet
A Handshake packet uses long headers with a type value of 0x7D. It A Handshake packet uses long headers with a type value of 0x7D. It
is used to carry acknowledgments and cryptographic handshake messages is used to carry acknowledgments and cryptographic handshake messages
from the server and client. from the server and client.
The connection ID field in a Handshake packet contains a connection The Destination Connection ID field in a Handshake packet contains a
ID that is chosen by the server (see Section 5.6). connection ID that is chosen by the recipient of the packet; the
Source Connection ID includes the connection ID that the sender of
the packet wishes to use (see Section 4.7).
The first Handshake packet sent by a server contains a randomized The first Handshake packet sent by a server contains a randomized
packet number. This value is increased for each subsequent packet packet number. This value is increased for each subsequent packet
sent by the server as described in Section 5.7. The client sent by the server as described in Section 4.8. The client
increments the packet number from its previous packet by one for each increments the packet number from its previous packet by one for each
Handshake packet that it sends (which might be an Initial, 0-RTT Handshake packet that it sends (which might be an Initial, 0-RTT
Protected, or Handshake packet). Protected, or Handshake packet).
Servers MUST NOT send more than three Handshake packets without Servers MUST NOT send more than three Handshake packets without
receiving a packet from a verified source address. Source addresses receiving a packet from a verified source address. Source addresses
can be verified through an address validation token, receipt of the can be verified through an address validation token, receipt of the
final cryptographic message from the client, or by receiving a valid final cryptographic message from the client, or by receiving a valid
PATH_RESPONSE frame from the client. PATH_RESPONSE frame from the client.
If the server expects to generate more than three Handshake packets If the server expects to generate more than three Handshake packets
in response to an Initial packet, it SHOULD include a PATH_CHALLENGE in response to an Initial packet, it SHOULD include a PATH_CHALLENGE
frame in each Handshake packet that it sends. After receiving at frame in each Handshake packet that it sends. After receiving at
least one valid PATH_RESPONSE frame, the server can send its least one valid PATH_RESPONSE frame, the server can send its
remaining Handshake packets. Servers can instead perform address remaining Handshake packets. Servers can instead perform address
validation using a Retry packet; this requires less state on the validation using a Retry packet; this requires less state on the
server, but could involve additional computational effort depending server, but could involve additional computational effort depending
on implementation choices. on implementation choices.
The payload of this packet contains STREAM frames and could contain The payload of this packet contains STREAM frames and could contain
PADDING, ACK, PATH_CHALLENGE, or PATH_RESPONSE frames. PADDING, ACK, PATH_CHALLENGE, or PATH_RESPONSE frames. Handshake
packets MAY contain CONNECTION_CLOSE frames if the handshake is
unsuccessful.
5.5. Protected Packets 4.5. Protected Packets
Packets that are protected with 0-RTT keys are sent with long Packets that are protected with 0-RTT keys are sent with long
headers; all packets protected with 1-RTT keys are sent with short headers; all packets protected with 1-RTT keys are sent with short
headers. The different packet types explicitly indicate the headers. The different packet types explicitly indicate the
encryption level and therefore the keys that are used to remove encryption level and therefore the keys that are used to remove
packet protection. packet protection.
Packets protected with 0-RTT keys use a type value of 0x7C. The Packets protected with 0-RTT keys use a type value of 0x7C. The
connection ID field for a 0-RTT packet is selected by the client. connection ID fields for a 0-RTT packet MUST match the values used in
the Initial packet (Section 4.4.1).
The client can send 0-RTT packets after receiving a Handshake packet The client can send 0-RTT packets after receiving a Handshake packet
(Section 5.4.3), if that packet does not complete the handshake. (Section 4.4.3), if that packet does not complete the handshake.
Even if the client receives a different connection ID in the Even if the client receives a different connection ID in the
Handshake packet, it MUST continue to use the connection ID selected Handshake packet, it MUST continue to use the same Destination
by the client for 0-RTT packets, see Section 5.6. Connection ID for 0-RTT packets, see Section 4.7.
The version field for protected packets is the current QUIC version. The version field for protected packets is the current QUIC version.
The packet number field contains a packet number, which increases The packet number field contains a packet number, which increases
with each packet sent, see Section 5.7 for details. with each packet sent, see Section 4.8 for details.
The payload is protected using authenticated encryption. [QUIC-TLS] The payload is protected using authenticated encryption. [QUIC-TLS]
describes packet protection in detail. After decryption, the describes packet protection in detail. After decryption, the
plaintext consists of a sequence of frames, as described in plaintext consists of a sequence of frames, as described in
Section 6. Section 5.
5.6. Connection ID 4.6. Coaslescing Packets
QUIC connections are identified by their 64-bit Connection ID. All A sender can coalesce multiple QUIC packets (typically a
long headers contain a Connection ID. Short headers indicate the Cryptographic Handshake packet and a Protected packet) into one UDP
presence of a Connection ID using the Omit Connection ID flag. When datagram. This can reduce the number of UDP datagrams needed to send
present, the Connection ID is in the same location in all packet application data during the handshake and immediately afterwards. A
headers, making it straightforward for middleboxes, such as load packet with a short header does not include a length, so it has to be
balancers, to locate and use it. the last packet included in a UDP datagram.
The client MUST choose a random connection ID and use it in Initial The sender MUST NOT coalesce QUIC packets belonging to different QUIC
packets (Section 5.4.1) and 0-RTT packets (Section 5.5). connections into a single UDP datagram.
When the server receives a Initial packet and decides to proceed with Every QUIC packet that is coalesced into a single UDP datagram is
the handshake, it chooses a new value for the connection ID and sends separate and complete. Though the values of some fields in the
that in a Retry (Section 5.4.2) or Handshake (Section 5.4.3) packet. packet header might be redundant, no fields are omitted. The
The server MAY choose to use the value that the client initially receiver of coalesced QUIC packets MUST individually process each
selects. QUIC packet and separately acknowledge them, as if they were received
as the payload of different UDP datagrams.
Once the client receives the connection ID that the server has 4.7. Connection ID
chosen, it MUST use it for all subsequent Handshake (Section 5.4.3)
and 1-RTT (Section 5.5) packets but not for 0-RTT packets
(Section 5.5).
Server's Version Negotiation (Section 5.3) and Retry (Section 5.4.2) A connection ID is used to ensure consistent routing of packets. The
packets MUST use connection ID selected by the client. long header contains two connection IDs: the Destination Connection
ID is chosen by the recipient of the packet and is used to provide
consistent routing; the Source Connection ID is used to set the
Destination Connection ID used by the peer.
5.7. Packet Numbers During the handshake, packets with the long header are used to
establish the connection ID that each endpoint uses. Each endpoint
uses the Source Connection ID field to specify the connection ID that
is used in the Destination Connection ID field of packets being sent
to them. Upon receiving a packet, each endpoint sets the Destination
Connection ID it sends to match the value of the Source Connection ID
that they receive.
During the handshake, an endpoint might receive multiple packets with
the long header, and thus be given multiple opportunities to update
the Destination Connection ID it sends. A client MUST only change
the value it sends in the Destination Connection ID in response to
the first packet of each type it receives from the server (Retry or
Handshake); a server MUST set its value based on the Initial packet.
Any additional changes are not permitted; if subsequent packets of
those types include a different Source Connection ID, they MUST be
discarded. This avoids problems that might arise from stateless
processing of multiple Initial packets producing different connection
IDs.
Short headers only include the Destination Connection ID and omit the
explicit length. The length of the Destination Connection ID field
is expected to be known to endpoints.
Endpoints using a connection-ID based load balancer could agree with
the load balancer on a fixed or minimum length and on an encoding for
connection IDs. This fixed portion could encode an explicit length,
which allows the entire connection ID to vary in length and still be
used by the load balancer.
The very first packet sent by a client includes a random value for
Destination Connection ID. The same value MUST be used for all 0-RTT
packets sent on that connection (Section 4.5). This randomized value
is used to determine the handshake packet protection keys (see
Section 5.3.2 of [QUIC-TLS]).
A Version Negotiation (Section 4.3) packet MUST use both connection
IDs selected by the client, swapped to ensure correct routing toward
the client.
The connection ID can change over the lifetime of a connection,
especially in response to connection migration (Section 6.8).
NEW_CONNECTION_ID frames (Section 7.13) are used to provide new
connection ID values.
4.8. Packet Numbers
The packet number is an integer in the range 0 to 2^62-1. The value The packet number is an integer in the range 0 to 2^62-1. The value
is used in determining the cryptographic nonce for packet encryption. is used in determining the cryptographic nonce for packet encryption.
Each endpoint maintains a separate packet number for sending and Each endpoint maintains a separate packet number for sending and
receiving. The packet number for sending MUST increase by at least receiving. The packet number for sending MUST increase by at least
one after sending any packet, unless otherwise specified (see one after sending any packet, unless otherwise specified (see
Section 5.7.1). Section 4.8.1).
A QUIC endpoint MUST NOT reuse a packet number within the same A QUIC endpoint MUST NOT reuse a packet number within the same
connection (that is, under the same cryptographic keys). If the connection (that is, under the same cryptographic keys). If the
packet number for sending reaches 2^62 - 1, the sender MUST close the packet number for sending reaches 2^62 - 1, the sender MUST close the
connection without sending a CONNECTION_CLOSE frame or any further connection without sending a CONNECTION_CLOSE frame or any further
packets; a server MAY send a Stateless Reset (Section 7.9.4) in packets; a server MAY send a Stateless Reset (Section 6.9.4) in
response to further packets that it receives. response to further packets that it receives.
For the packet header, the number of bits required to represent the For the packet header, the number of bits required to represent the
packet number are reduced by including only the least significant packet number are reduced by including only the least significant
bits of the packet number. The actual packet number for each packet bits of the packet number. The actual packet number for each packet
is reconstructed at the receiver based on the largest packet number is reconstructed at the receiver based on the largest packet number
received on a successfully authenticated packet. received on a successfully authenticated packet.
A packet number is decoded by finding the packet number value that is A packet number is decoded by finding the packet number value that is
closest to the next expected packet. The next expected packet is the closest to the next expected packet. The next expected packet is the
skipping to change at page 19, line 24 skipping to change at page 20, line 14
As a result, the size of the packet number encoding is at least one As a result, the size of the packet number encoding is at least one
more than the base 2 logarithm of the number of contiguous more than the base 2 logarithm of the number of contiguous
unacknowledged packet numbers, including the new packet. unacknowledged packet numbers, including the new packet.
For example, if an endpoint has received an acknowledgment for packet For example, if an endpoint has received an acknowledgment for packet
0x6afa2f, sending a packet with a number of 0x6b4264 requires a 0x6afa2f, sending a packet with a number of 0x6b4264 requires a
16-bit or larger packet number encoding; whereas a 32-bit packet 16-bit or larger packet number encoding; whereas a 32-bit packet
number is needed to send a packet with a number of 0x6bc107. number is needed to send a packet with a number of 0x6bc107.
A Version Negotiation packet (Section 5.3) does not include a packet A Version Negotiation packet (Section 4.3) does not include a packet
number. The Retry packet (Section 5.4.2) has special rules for number. The Retry packet (Section 4.4.2) has special rules for
populating the packet number field. populating the packet number field.
5.7.1. Initial Packet Number 4.8.1. Initial Packet Number
The initial value for packet number MUST be selected randomly from a The initial value for packet number MUST be selected randomly from a
range between 0 and 2^32 - 1025 (inclusive). This value is selected range between 0 and 2^32 - 1025 (inclusive). This value is selected
so that Initial and Handshake packets exercise as many possible so that Initial and Handshake packets exercise as many possible
values for the Packet Number field as possible. values for the Packet Number field as possible.
Limiting the range allows both for loss of packets and for any Limiting the range allows both for loss of packets and for any
stateless exchanges. Packet numbers are incremented for subsequent stateless exchanges. Packet numbers are incremented for subsequent
packets, but packet loss and stateless handling can both mean that packets, but packet loss and stateless handling can both mean that
the first packet sent by an endpoint isn't necessarily the first the first packet sent by an endpoint isn't necessarily the first
packet received by its peer. The first packet received by a peer packet received by its peer. The first packet received by a peer
cannot be 2^32 or greater or the recipient will incorrectly assume a cannot be 2^32 or greater or the recipient will incorrectly assume a
packet number that is 2^32 values lower and discard the packet. packet number that is 2^32 values lower and discard the packet.
Use of a secure random number generator [RFC4086] is not necessary Use of a secure random number generator [RFC4086] is not necessary
for generating the initial packet number, nor is it necessary that for generating the initial packet number, nor is it necessary that
the value be uniformly distributed. the value be uniformly distributed.
6. Frames and Frame Types 5. Frames and Frame Types
The payload of all packets, after removing packet protection, The payload of all packets, after removing packet protection,
consists of a sequence of frames, as shown in Figure 4. Version consists of a sequence of frames, as shown in Figure 4. Version
Negotiation and Stateless Reset do not contain frames. Negotiation and Stateless Reset do not contain frames.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame 1 (*) ... | Frame 1 (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 20, line 35 skipping to change at page 21, line 35
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (8) | Type-Dependent Fields (*) ... | Type (8) | Type-Dependent Fields (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Generic Frame Layout Figure 5: Generic Frame Layout
Frame types are listed in Table 3. Note that the Frame Type byte in Frame types are listed in Table 3. Note that the Frame Type byte in
STREAM and ACK frames is used to carry other frame-specific flags. STREAM frames is used to carry other frame-specific flags. For all
For all other frames, the Frame Type byte simply identifies the other frames, the Frame Type byte simply identifies the frame. These
frame. These frames are explained in more detail as they are frames are explained in more detail as they are referenced later in
referenced later in the document. the document.
+-------------+-------------------+--------------+ +-------------+-------------------+--------------+
| Type Value | Frame Type Name | Definition | | Type Value | Frame Type Name | Definition |
+-------------+-------------------+--------------+ +-------------+-------------------+--------------+
| 0x00 | PADDING | Section 8.2 | | 0x00 | PADDING | Section 7.2 |
| | | | | | | |
| 0x01 | RST_STREAM | Section 8.3 | | 0x01 | RST_STREAM | Section 7.3 |
| | | | | | | |
| 0x02 | CONNECTION_CLOSE | Section 8.4 | | 0x02 | CONNECTION_CLOSE | Section 7.4 |
| | | | | | | |
| 0x03 | APPLICATION_CLOSE | Section 8.5 | | 0x03 | APPLICATION_CLOSE | Section 7.5 |
| | | | | | | |
| 0x04 | MAX_DATA | Section 8.6 | | 0x04 | MAX_DATA | Section 7.6 |
| | | | | | | |
| 0x05 | MAX_STREAM_DATA | Section 8.7 | | 0x05 | MAX_STREAM_DATA | Section 7.7 |
| | | | | | | |
| 0x06 | MAX_STREAM_ID | Section 8.8 | | 0x06 | MAX_STREAM_ID | Section 7.8 |
| | | | | | | |
| 0x07 | PING | Section 8.9 | | 0x07 | PING | Section 7.9 |
| | | | | | | |
| 0x08 | BLOCKED | Section 8.10 | | 0x08 | BLOCKED | Section 7.10 |
| | | | | | | |
| 0x09 | STREAM_BLOCKED | Section 8.11 | | 0x09 | STREAM_BLOCKED | Section 7.11 |
| | | | | | | |
| 0x0a | STREAM_ID_BLOCKED | Section 8.12 | | 0x0a | STREAM_ID_BLOCKED | Section 7.12 |
| | | | | | | |
| 0x0b | NEW_CONNECTION_ID | Section 8.13 | | 0x0b | NEW_CONNECTION_ID | Section 7.13 |
| | | | | | | |
| 0x0c | STOP_SENDING | Section 8.14 | | 0x0c | STOP_SENDING | Section 7.14 |
| | | | | | | |
| 0x0d | ACK | Section 8.15 | | 0x0d | ACK | Section 7.15 |
| | | | | | | |
| 0x0e | PATH_CHALLENGE | Section 8.16 | | 0x0e | PATH_CHALLENGE | Section 7.16 |
| | | | | | | |
| 0x0f | PATH_RESPONSE | Section 8.17 | | 0x0f | PATH_RESPONSE | Section 7.17 |
| | | | | | | |
| 0x10 - 0x17 | STREAM | Section 8.18 | | 0x10 - 0x17 | STREAM | Section 7.18 |
+-------------+-------------------+--------------+ +-------------+-------------------+--------------+
Table 3: Frame Types Table 3: Frame Types
7. Life of a Connection 6. Life of a Connection
A QUIC connection is a single conversation between two QUIC A QUIC connection is a single conversation between two QUIC
endpoints. QUIC's connection establishment intertwines version endpoints. QUIC's connection establishment intertwines version
negotiation with the cryptographic and transport handshakes to reduce negotiation with the cryptographic and transport handshakes to reduce
connection establishment latency, as described in Section 7.3. Once connection establishment latency, as described in Section 6.3. Once
established, a connection may migrate to a different IP or port at established, a connection may migrate to a different IP or port at
either endpoint, due to NAT rebinding or mobility, as described in either endpoint, due to NAT rebinding or mobility, as described in
Section 7.7. Finally a connection may be terminated by either Section 6.8. Finally a connection may be terminated by either
endpoint, as described in Section 7.9. endpoint, as described in Section 6.9.
7.1. Matching Packets to Connections 6.1. Matching Packets to Connections
Incoming packets are classified on receipt. Packets can either be Incoming packets are classified on receipt. Packets can either be
associated with an existing connection, or - for servers - associated with an existing connection, or - for servers -
potentially create a new connection. potentially create a new connection.
Hosts try to associate the packet with an existing connection. If Hosts try to associate a packet with an existing connection. If the
the packet has a connection ID corresponding to an existing packet has a Destination Connection ID corresponding to an existing
connection, QUIC processes that packet accordingly. Note that a connection, QUIC processes that packet accordingly. Note that a
NEW_CONNECTION_ID frame (Section 8.13) would associate more than one NEW_CONNECTION_ID frame (Section 7.13) would associate more than one
connection ID with a connection. connection ID with a connection.
If there is no connection ID, but the packet matches the address/port If the Destination Connection ID is zero length and the packet
tuple of a connection where the host did not require connection IDs, matches the address/port tuple of a connection where the host did not
QUIC processes the packet as part of that connection. Endpoints MUST require connection IDs, QUIC processes the packet as part of that
drop packets that omit connection IDs if they do not meet both of connection. Endpoints MUST drop packets with zero-length Destination
these criteria. Connection ID fields if they do not correspond to a single
connection.
7.1.1. Client Packet Handling
If a client receives a packet with an unknown connection ID, and it 6.1.1. Client Packet Handling
matches the tuple of a connection with no received packets, it is a
reply to an Initial packet with a server-generated connection ID and
will be processed accordingly. Clients SHOULD discard any packets
with new connection IDs that do not meet these criteria.
Note that a successfully associated packet may be a Version Valid packets sent to clients always include a Destination Connection
Negotiation packet, which is handled in accordance with ID that matches the value the client selects. Clients that choose to
Section 7.2.2. receive zero-length connection IDs can use the address/port tuple to
identify a connection. Packets that don't match an existing
connection MAY be discarded.
Due to packet reordering or loss, clients might receive packets for a Due to packet reordering or loss, clients might receive packets for a
connection encrypted with a key it has not yet computed. Clients MAY connection that are encrypted with a key it has not yet computed.
drop these packets, or MAY buffer them in anticipation of later Clients MAY drop these packets, or MAY buffer them in anticipation of
packets that allow it to compute the key. later packets that allow it to compute the key.
7.1.2. Server Packet Handling If a client receives a packet that has an unsupported version, it
MUST discard that packet.
6.1.2. Server Packet Handling
If a server receives a packet that has an unsupported version and If a server receives a packet that has an unsupported version and
sufficient length to be an Initial packet for some version supported sufficient length to be an Initial packet for some version supported
by the server, it SHOULD send a Version Negotiation packet as by the server, it SHOULD send a Version Negotiation packet as
described in Section 7.2.1. Servers MAY rate control these packets described in Section 6.2.1. Servers MAY rate control these packets
to avoid storms of Version Negotiation packets. to avoid storms of Version Negotiation packets.
The first packet for an unsupported version can use different
semantics and encodings for any version-specific field. In
particular, different packet protection keys might be used for
different versions. Servers that do not support a particular version
are unlikely to be able to decrypt the content of the packet.
Servers SHOULD NOT attempt to decode or decrypt a packet from an
unknown version, but instead send a Version Negotiation packet,
provided that the packet is sufficiently long.
Servers MUST drop other packets that contain unsupported versions. Servers MUST drop other packets that contain unsupported versions.
Packets with a supported version, or no version field, are matched to Packets with a supported version, or no version field, are matched to
a connection as described in Section 7.1. If not matched, the server a connection as described in Section 6.1. If not matched, the server
continues below. continues below.
If the packet is an Initial packet fully conforming with the If the packet is an Initial packet fully conforming with the
specification, the server proceeds with the handshake (Section 7.3). specification, the server proceeds with the handshake (Section 6.3).
This commits the server to the version that the client selected. This commits the server to the version that the client selected.
If a server isn't currently accepting any new connections, it SHOULD If a server isn't currently accepting any new connections, it SHOULD
send a Handshake packet containing a CONNECTION_CLOSE frame with send a Handshake packet containing a CONNECTION_CLOSE frame with
error code SERVER_BUSY. error code SERVER_BUSY.
If the packet is a 0-RTT packet, the server MAY buffer a limited If the packet is a 0-RTT packet, the server MAY buffer a limited
number of these packets in anticipation of a late-arriving Initial number of these packets in anticipation of a late-arriving Initial
Packet. Clients are forbidden from sending Handshake packets prior Packet. Clients are forbidden from sending Handshake packets prior
to receiving a server response, so servers SHOULD ignore any such to receiving a server response, so servers SHOULD ignore any such
packets. packets.
Servers MUST drop incoming packets under all other circumstances. Servers MUST drop incoming packets under all other circumstances.
They SHOULD send a Stateless Reset (Section 7.9.4) if a connection ID They SHOULD send a Stateless Reset (Section 6.9.4) if a connection ID
is present in the header. is present in the header.
7.2. Version Negotiation 6.2. Version Negotiation
Version negotiation ensures that client and server agree to a QUIC Version negotiation ensures that client and server agree to a QUIC
version that is mutually supported. A server sends a Version version that is mutually supported. A server sends a Version
Negotiation packet in response to each packet that might initiate a Negotiation packet in response to each packet that might initiate a
new connection, see Section 7.1 for details. new connection, see Section 6.1 for details.
The size of the first packet sent by a client will determine whether The size of the first packet sent by a client will determine whether
a server sends a Version Negotiation packet. Clients that support a server sends a Version Negotiation packet. Clients that support
multiple QUIC versions SHOULD pad their Initial packets to reflect multiple QUIC versions SHOULD pad their Initial packets to reflect
the largest minimum Initial packet size of all their versions. This the largest minimum Initial packet size of all their versions. This
ensures that that the server responds if there are any mutually ensures that that the server responds if there are any mutually
supported versions. supported versions.
7.2.1. Sending Version Negotiation Packets 6.2.1. Sending Version Negotiation Packets
If the version selected by the client is not acceptable to the If the version selected by the client is not acceptable to the
server, the server responds with a Version Negotiation packet server, the server responds with a Version Negotiation packet (see
(Section 5.3). This includes a list of versions that the server will Section 4.3). This includes a list of versions that the server will
accept. accept.
This system allows a server to process packets with unsupported This system allows a server to process packets with unsupported
versions without retaining state. Though either the Initial packet versions without retaining state. Though either the Initial packet
or the Version Negotiation packet that is sent in response could be or the Version Negotiation packet that is sent in response could be
lost, the client will send new packets until it successfully receives lost, the client will send new packets until it successfully receives
a response or it abandons the connection attempt. a response or it abandons the connection attempt.
7.2.2. Handling Version Negotiation Packets 6.2.2. Handling Version Negotiation Packets
When the client receives a Version Negotiation packet, it first When the client receives a Version Negotiation packet, it first
checks that the connection ID matches the connection ID the client checks that the Destination and Source Connection ID fields match the
sent. If this check fails, the packet MUST be discarded. Source and Destination Connection ID fields in a packet that the
client sent. If this check fails, the packet MUST be discarded.
Once the Version Negotiation packet is determined to be valid, the Once the Version Negotiation packet is determined to be valid, the
client then selects an acceptable protocol version from the list client then selects an acceptable protocol version from the list
provided by the server. The client then attempts to create a provided by the server. The client then attempts to create a
connection using that version. Though the contents of the Client connection using that version. Though the contents of the Initial
Initial packet the client sends might not change in response to packet the client sends might not change in response to version
version negotiation, a client MUST increase the packet number it uses negotiation, a client MUST increase the packet number it uses on
on every packet it sends. Packets MUST continue to use long headers every packet it sends. Packets MUST continue to use long headers and
and MUST include the new negotiated protocol version. MUST include the new negotiated protocol version.
The client MUST use the long header format and include its selected The client MUST use the long header format and include its selected
version on all packets until it has 1-RTT keys and it has received a version on all packets until it has 1-RTT keys and it has received a
packet from the server which is not a Version Negotiation packet. packet from the server which is not a Version Negotiation packet.
A client MUST NOT change the version it uses unless it is in response A client MUST NOT change the version it uses unless it is in response
to a Version Negotiation packet from the server. Once a client to a Version Negotiation packet from the server. Once a client
receives a packet from the server which is not a Version Negotiation receives a packet from the server which is not a Version Negotiation
packet, it MUST discard other Version Negotiation packets on the same packet, it MUST discard other Version Negotiation packets on the same
connection. Similarly, a client MUST ignore a Version Negotiation connection. Similarly, a client MUST ignore a Version Negotiation
packet if it has already received and acted on a Version Negotiation packet if it has already received and acted on a Version Negotiation
packet. packet.
A client MUST ignore a Version Negotiation packet that lists the A client MUST ignore a Version Negotiation packet that lists the
client's chosen version. client's chosen version.
Version negotiation packets have no cryptographic protection. The Version negotiation packets have no cryptographic protection. The
result of the negotiation MUST be revalidated as part of the result of the negotiation MUST be revalidated as part of the
cryptographic handshake (see Section 7.4.4). cryptographic handshake (see Section 6.4.4).
7.2.3. Using Reserved Versions 6.2.3. Using Reserved Versions
For a server to use a new version in the future, clients must For a server to use a new version in the future, clients must
correctly handle unsupported versions. To help ensure this, a server correctly handle unsupported versions. To help ensure this, a server
SHOULD include a reserved version (see Section 4) while generating a SHOULD include a reserved version (see Section 3) while generating a
Version Negotiation packet. Version Negotiation packet.
The design of version negotiation permits a server to avoid The design of version negotiation permits a server to avoid
maintaining state for packets that it rejects in this fashion. The maintaining state for packets that it rejects in this fashion. The
validation of version negotiation (see Section 7.4.4) only validates validation of version negotiation (see Section 6.4.4) only validates
the result of version negotiation, which is the same no matter which the result of version negotiation, which is the same no matter which
reserved version was sent. A server MAY therefore send different reserved version was sent. A server MAY therefore send different
reserved version numbers in the Version Negotiation Packet and in its reserved version numbers in the Version Negotiation Packet and in its
transport parameters. transport parameters.
A client MAY send a packet using a reserved version number. This can A client MAY send a packet using a reserved version number. This can
be used to solicit a list of supported versions from a server. be used to solicit a list of supported versions from a server.
7.3. Cryptographic and Transport Handshake 6.3. Cryptographic and Transport Handshake
QUIC relies on a combined cryptographic and transport handshake to QUIC relies on a combined cryptographic and transport handshake to
minimize connection establishment latency. QUIC allocates stream 0 minimize connection establishment latency. QUIC allocates stream 0
for the cryptographic handshake. Version 0x00000001 of QUIC uses TLS for the cryptographic handshake. Version 0x00000001 of QUIC uses TLS
1.3 as described in [QUIC-TLS]; a different QUIC version number could 1.3 as described in [QUIC-TLS]; a different QUIC version number could
indicate that a different cryptographic handshake protocol is in use. indicate that a different cryptographic handshake protocol is in use.
QUIC provides this stream with reliable, ordered delivery of data. QUIC provides this stream with reliable, ordered delivery of data.
In return, the cryptographic handshake provides QUIC with: In return, the cryptographic handshake provides QUIC with:
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* a client is optionally authenticated, * a client is optionally authenticated,
* every connection produces distinct and unrelated keys, * every connection produces distinct and unrelated keys,
* keying material is usable for packet protection for both 0-RTT * keying material is usable for packet protection for both 0-RTT
and 1-RTT packets, and and 1-RTT packets, and
* 1-RTT keys have forward secrecy * 1-RTT keys have forward secrecy
o authenticated values for the transport parameters of the peer (see o authenticated values for the transport parameters of the peer (see
Section 7.4) Section 6.4)
o authenticated confirmation of version negotiation (see o authenticated confirmation of version negotiation (see
Section 7.4.4) Section 6.4.4)
o authenticated negotiation of an application protocol (TLS uses o authenticated negotiation of an application protocol (TLS uses
ALPN [RFC7301] for this purpose) ALPN [RFC7301] for this purpose)
o for the server, the ability to carry data that provides assurance o for the server, the ability to carry data that provides assurance
that the client can receive packets that are addressed with the that the client can receive packets that are addressed with the
transport address that is claimed by the client (see Section 7.6) transport address that is claimed by the client (see Section 6.6)
The initial cryptographic handshake message MUST be sent in a single The initial cryptographic handshake message MUST be sent in a single
packet. Any second attempt that is triggered by address validation packet. Any second attempt that is triggered by address validation
MUST also be sent within a single packet. This avoids having to MUST also be sent within a single packet. This avoids having to
reassemble a message from multiple packets. Reassembling messages reassemble a message from multiple packets. Reassembling messages
requires that a server maintain state prior to establishing a requires that a server maintain state prior to establishing a
connection, exposing the server to a denial of service risk. connection, exposing the server to a denial of service risk.
The first client packet of the cryptographic handshake protocol MUST The first client packet of the cryptographic handshake protocol MUST
fit within a 1232 octet QUIC packet payload. This includes overheads fit within a 1232 octet QUIC packet payload. This includes overheads
that reduce the space available to the cryptographic handshake that reduce the space available to the cryptographic handshake
protocol. protocol.
Details of how TLS is integrated with QUIC is provided in more detail Details of how TLS is integrated with QUIC is provided in more detail
in [QUIC-TLS]. in [QUIC-TLS].
7.4. Transport Parameters 6.4. Transport Parameters
During connection establishment, both endpoints make authenticated During connection establishment, both endpoints make authenticated
declarations of their transport parameters. These declarations are declarations of their transport parameters. These declarations are
made unilaterally by each endpoint. Endpoints are required to comply made unilaterally by each endpoint. Endpoints are required to comply
with the restrictions implied by these parameters; the description of with the restrictions implied by these parameters; the description of
each parameter includes rules for its handling. each parameter includes rules for its handling.
The format of the transport parameters is the TransportParameters The format of the transport parameters is the TransportParameters
struct from Figure 6. This is described using the presentation struct from Figure 6. This is described using the presentation
language from Section 3 of [I-D.ietf-tls-tls13]. language from Section 3 of [I-D.ietf-tls-tls13].
uint32 QuicVersion; uint32 QuicVersion;
enum { enum {
initial_max_stream_data(0), initial_max_stream_data(0),
initial_max_data(1), initial_max_data(1),
initial_max_stream_id_bidi(2), initial_max_stream_id_bidi(2),
idle_timeout(3), idle_timeout(3),
omit_connection_id(4),
max_packet_size(5), max_packet_size(5),
stateless_reset_token(6), stateless_reset_token(6),
ack_delay_exponent(7), ack_delay_exponent(7),
initial_max_stream_id_uni(8), initial_max_stream_id_uni(8),
(65535) (65535)
} TransportParameterId; } TransportParameterId;
struct { struct {
TransportParameterId parameter; TransportParameterId parameter;
opaque value<0..2^16-1>; opaque value<0..2^16-1>;
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The "extension_data" field of the quic_transport_parameters extension The "extension_data" field of the quic_transport_parameters extension
defined in [QUIC-TLS] contains a TransportParameters value. TLS defined in [QUIC-TLS] contains a TransportParameters value. TLS
encoding rules are therefore used to encode the transport parameters. encoding rules are therefore used to encode the transport parameters.
QUIC encodes transport parameters into a sequence of octets, which QUIC encodes transport parameters into a sequence of octets, which
are then included in the cryptographic handshake. Once the handshake are then included in the cryptographic handshake. Once the handshake
completes, the transport parameters declared by the peer are completes, the transport parameters declared by the peer are
available. Each endpoint validates the value provided by its peer. available. Each endpoint validates the value provided by its peer.
In particular, version negotiation MUST be validated (see In particular, version negotiation MUST be validated (see
Section 7.4.4) before the connection establishment is considered Section 6.4.4) before the connection establishment is considered
properly complete. properly complete.
Definitions for each of the defined transport parameters are included Definitions for each of the defined transport parameters are included
in Section 7.4.1. Any given parameter MUST appear at most once in a in Section 6.4.1. Any given parameter MUST appear at most once in a
given transport parameters extension. An endpoint MUST treat receipt given transport parameters extension. An endpoint MUST treat receipt
of duplicate transport parameters as a connection error of type of duplicate transport parameters as a connection error of type
TRANSPORT_PARAMETER_ERROR. TRANSPORT_PARAMETER_ERROR.
7.4.1. Transport Parameter Definitions 6.4.1. Transport Parameter Definitions
An endpoint MUST include the following parameters in its encoded An endpoint MUST include the following parameters in its encoded
TransportParameters: TransportParameters:
initial_max_stream_data (0x0000): The initial stream maximum data initial_max_stream_data (0x0000): The initial stream maximum data
parameter contains the initial value for the maximum data that can parameter contains the initial value for the maximum data that can
be sent on any newly created stream. This parameter is encoded as be sent on any newly created stream. This parameter is encoded as
an unsigned 32-bit integer in units of octets. This is equivalent an unsigned 32-bit integer in units of octets. This is equivalent
to an implicit MAX_STREAM_DATA frame (Section 8.7) being sent on to an implicit MAX_STREAM_DATA frame (Section 7.7) being sent on
all streams immediately after opening. all streams immediately after opening.
initial_max_data (0x0001): The initial maximum data parameter initial_max_data (0x0001): The initial maximum data parameter
contains the initial value for the maximum amount of data that can contains the initial value for the maximum amount of data that can
be sent on the connection. This parameter is encoded as an be sent on the connection. This parameter is encoded as an
unsigned 32-bit integer in units of octets. This is equivalent to unsigned 32-bit integer in units of octets. This is equivalent to
sending a MAX_DATA (Section 8.6) for the connection immediately sending a MAX_DATA (Section 7.6) for the connection immediately
after completing the handshake. after completing the handshake.
idle_timeout (0x0003): The idle timeout is a value in seconds that idle_timeout (0x0003): The idle timeout is a value in seconds that
is encoded as an unsigned 16-bit integer. The maximum value is is encoded as an unsigned 16-bit integer. The maximum value is
600 seconds (10 minutes). 600 seconds (10 minutes).
A server MUST include the following transport parameters:
stateless_reset_token (0x0006): The Stateless Reset Token is used in
verifying a stateless reset, see Section 7.9.4. This parameter is
a sequence of 16 octets.
A client MUST NOT include a stateless reset token. A server MUST
treat receipt of a stateless_reset_token transport parameter as a
connection error of type TRANSPORT_PARAMETER_ERROR.
An endpoint MAY use the following transport parameters: An endpoint MAY use the following transport parameters:
initial_max_stream_id_bidi (0x0002): The initial maximum stream ID initial_max_streams_bidi (0x0002): The initial maximum bidirectional
parameter contains the initial maximum stream number the peer may streams parameter contains the initial maximum number of
initiate for bidirectional streams, encoded as an unsigned 32-bit application-owned bidirectional streams the peer may initiate,
integer. This value MUST be a valid bidirectional stream ID for a encoded as an unsigned 16-bit integer. If this parameter is
peer-initiated stream (that is, the two least significant bits are absent or zero, application-owned bidirectional streams cannot be
set to 0 by a server and to 1 by a client). If an invalid value created until a MAX_STREAM_ID frame is sent. Note that a value of
is provided, the recipient MUST generate a connection error of 0 does not prevent the cryptographic handshake stream (that is,
type TRANSPORT_PARAMETER_ERROR. Setting this parameter is stream 0) from being used. Setting this parameter is equivalent
equivalent to sending a MAX_STREAM_ID (Section 8.8) immediately to sending a MAX_STREAM_ID (Section 7.8) immediately after
after completing the handshake. The maximum bidirectional stream completing the handshake containing the corresponding Stream ID.
ID is set to 0 if this parameter is absent, preventing the For example, a value of 0x05 would be equivalent to receiving a
creation of new bidirectional streams until a MAX_STREAM_ID frame MAX_STREAM_ID containing 20 when received by a client or 17 when
is sent. Note that a default value of 0 does not prevent the received by a server.
cryptographic handshake stream (that is, stream 0) from being
used.
initial_max_stream_id_uni (0x0008): The initial maximum stream ID
parameter contains the initial maximum stream number the peer may
initiate for unidirectional streams, encoded as an unsigned 32-bit
integer. The value MUST be a valid unidirectional ID for the
recipient (that is, the two least significant bits are set to 2 by
a server and to 3 by a client). If an invalid value is provided,
the recipient MUST generate a connection error of type
TRANSPORT_PARAMETER_ERROR. Setting this parameter is equivalent
to sending a MAX_STREAM_ID (Section 8.8) immediately after
completing the handshake. The maximum unidirectional stream ID is
set to 0 if this parameter is absent, preventing the creation of
new unidirectional streams until a MAX_STREAM_ID frame is sent.
omit_connection_id (0x0004): The omit connection identifier initial_max_stream_id_uni (0x0008): The initial maximum
parameter indicates that packets sent to the endpoint that unidirectional streams parameter contains the initial maximum
advertises this parameter MAY omit the connection ID in packets number of application-owned unidirectional streams the peer may
using short header format. This can be used by an endpoint where initiate, encoded as an unsigned 16-bit integer. If this
it knows that source and destination IP address and port are parameter is absent or zero, unidirectional streams cannot be
sufficient for it to identify a connection. This parameter is created until a MAX_STREAM_ID frame is sent. Setting this
zero length. Absence of this parameter means that the connection parameter is equivalent to sending a MAX_STREAM_ID (Section 7.8)
ID MUST be present in every packet sent to this endpoint. immediately after completing the handshake containing the
corresponding Stream ID. For example, a value of 0x05 would be
equivalent to receiving a MAX_STREAM_ID containing 18 when
received by a client or 19 when received by a server.
max_packet_size (0x0005): The maximum packet size parameter places a max_packet_size (0x0005): The maximum packet size parameter places a
limit on the size of packets that the endpoint is willing to limit on the size of packets that the endpoint is willing to
receive, encoded as an unsigned 16-bit integer. This indicates receive, encoded as an unsigned 16-bit integer. This indicates
that packets larger than this limit will be dropped. The default that packets larger than this limit will be dropped. The default
for this parameter is the maximum permitted UDP payload of 65527. for this parameter is the maximum permitted UDP payload of 65527.
Values below 1200 are invalid. This limit only applies to Values below 1200 are invalid. This limit only applies to
protected packets (Section 5.5). protected packets (Section 4.5).
ack_delay_exponent (0x0007): An 8-bit unsigned integer value ack_delay_exponent (0x0007): An 8-bit unsigned integer value
indicating an exponent used to decode the ACK Delay field in the indicating an exponent used to decode the ACK Delay field in the
ACK frame, see Section 8.15. If this value is absent, a default ACK frame, see Section 7.15. If this value is absent, a default
value of 3 is assumed (indicating a multiplier of 8). The default value of 3 is assumed (indicating a multiplier of 8). The default
value is also used for ACK frames that are sent in Initial, value is also used for ACK frames that are sent in Initial,
Handshake, and Retry packets. Values above 20 are invalid. Handshake, and Retry packets. Values above 20 are invalid.
7.4.2. Values of Transport Parameters for 0-RTT A server MAY include the following transport parameters:
stateless_reset_token (0x0006): The Stateless Reset Token is used in
verifying a stateless reset, see Section 6.9.4. This parameter is
a sequence of 16 octets.
A client MUST NOT include a stateless reset token. A server MUST
treat receipt of a stateless_reset_token transport parameter as a
connection error of type TRANSPORT_PARAMETER_ERROR.
6.4.2. Values of Transport Parameters for 0-RTT
A client that attempts to send 0-RTT data MUST remember the transport A client that attempts to send 0-RTT data MUST remember the transport
parameters used by the server. The transport parameters that the parameters used by the server. The transport parameters that the
server advertises during connection establishment apply to all server advertises during connection establishment apply to all
connections that are resumed using the keying material established connections that are resumed using the keying material established
during that handshake. Remembered transport parameters apply to the during that handshake. Remembered transport parameters apply to the
new connection until the handshake completes and new transport new connection until the handshake completes and new transport
parameters from the server can be provided. parameters from the server can be provided.
A server can remember the transport parameters that it advertised, or A server can remember the transport parameters that it advertised, or
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Omitting or setting a zero value for certain transport parameters can Omitting or setting a zero value for certain transport parameters can
result in 0-RTT data being enabled, but not usable. The following result in 0-RTT data being enabled, but not usable. The following
transport parameters SHOULD be set to non-zero values for 0-RTT: transport parameters SHOULD be set to non-zero values for 0-RTT:
initial_max_stream_id_bidi, initial_max_stream_id_uni, initial_max_stream_id_bidi, initial_max_stream_id_uni,
initial_max_data, initial_max_stream_data. initial_max_data, initial_max_stream_data.
A server MUST reject 0-RTT data or even abort a handshake if the A server MUST reject 0-RTT data or even abort a handshake if the
implied values for transport parameters cannot be supported. implied values for transport parameters cannot be supported.
7.4.3. New Transport Parameters 6.4.3. New Transport Parameters
New transport parameters can be used to negotiate new protocol New transport parameters can be used to negotiate new protocol
behavior. An endpoint MUST ignore transport parameters that it does behavior. An endpoint MUST ignore transport parameters that it does
not support. Absence of a transport parameter therefore disables any not support. Absence of a transport parameter therefore disables any
optional protocol feature that is negotiated using the parameter. optional protocol feature that is negotiated using the parameter.
New transport parameters can be registered according to the rules in New transport parameters can be registered according to the rules in
Section 14.1. Section 13.1.
7.4.4. Version Negotiation Validation 6.4.4. Version Negotiation Validation
Though the cryptographic handshake has integrity protection, two Though the cryptographic handshake has integrity protection, two
forms of QUIC version downgrade are possible. In the first, an forms of QUIC version downgrade are possible. In the first, an
attacker replaces the QUIC version in the Initial packet. In the attacker replaces the QUIC version in the Initial packet. In the
second, a fake Version Negotiation packet is sent by an attacker. To second, a fake Version Negotiation packet is sent by an attacker. To
protect against these attacks, the transport parameters include three protect against these attacks, the transport parameters include three
fields that encode version information. These parameters are used to fields that encode version information. These parameters are used to
retroactively authenticate the choice of version (see Section 7.2). retroactively authenticate the choice of version (see Section 6.2).
The cryptographic handshake provides integrity protection for the The cryptographic handshake provides integrity protection for the
negotiated version as part of the transport parameters (see negotiated version as part of the transport parameters (see
Section 7.4). As a result, attacks on version negotiation by an Section 6.4). As a result, attacks on version negotiation by an
attacker can be detected. attacker can be detected.
The client includes the initial_version field in its transport The client includes the initial_version field in its transport
parameters. The initial_version is the version that the client parameters. The initial_version is the version that the client
initially attempted to use. If the server did not send a Version initially attempted to use. If the server did not send a Version
Negotiation packet Section 5.3, this will be identical to the Negotiation packet Section 4.3, this will be identical to the
negotiated_version field in the server transport parameters. negotiated_version field in the server transport parameters.
A server that processes all packets in a stateful fashion can A server that processes all packets in a stateful fashion can
remember how version negotiation was performed and validate the remember how version negotiation was performed and validate the
initial_version value. initial_version value.
A server that does not maintain state for every packet it receives A server that does not maintain state for every packet it receives
(i.e., a stateless server) uses a different process. If the (i.e., a stateless server) uses a different process. If the
initial_version matches the version of QUIC that is in use, a initial_version matches the version of QUIC that is in use, a
stateless server can accept the value. stateless server can accept the value.
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The negotiated_version field is the version that is in use. This The negotiated_version field is the version that is in use. This
MUST be set by the server to the value that is on the Initial packet MUST be set by the server to the value that is on the Initial packet
that it accepts (not an Initial packet that triggers a Retry or that it accepts (not an Initial packet that triggers a Retry or
Version Negotiation packet). A client that receives a Version Negotiation packet). A client that receives a
negotiated_version that does not match the version of QUIC that is in negotiated_version that does not match the version of QUIC that is in
use MUST terminate the connection with a VERSION_NEGOTIATION_ERROR use MUST terminate the connection with a VERSION_NEGOTIATION_ERROR
error code. error code.
The server includes a list of versions that it would send in any The server includes a list of versions that it would send in any
version negotiation packet (Section 5.3) in the supported_versions version negotiation packet (Section 4.3) in the supported_versions
field. The server populates this field even if it did not send a field. The server populates this field even if it did not send a
version negotiation packet. version negotiation packet.
The client validates that the negotiated_version is included in the The client validates that the negotiated_version is included in the
supported_versions list and - if version negotiation was performed - supported_versions list and - if version negotiation was performed -
that it would have selected the negotiated version. A client MUST that it would have selected the negotiated version. A client MUST
terminate the connection with a VERSION_NEGOTIATION_ERROR error code terminate the connection with a VERSION_NEGOTIATION_ERROR error code
if the current QUIC version is not listed in the supported_versions if the current QUIC version is not listed in the supported_versions
list. A client MUST terminate with a VERSION_NEGOTIATION_ERROR error list. A client MUST terminate with a VERSION_NEGOTIATION_ERROR error
code if version negotiation occurred but it would have selected a code if version negotiation occurred but it would have selected a
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When an endpoint accepts multiple QUIC versions, it can potentially When an endpoint accepts multiple QUIC versions, it can potentially
interpret transport parameters as they are defined by any of the QUIC interpret transport parameters as they are defined by any of the QUIC
versions it supports. The version field in the QUIC packet header is versions it supports. The version field in the QUIC packet header is
authenticated using transport parameters. The position and the authenticated using transport parameters. The position and the
format of the version fields in transport parameters MUST either be format of the version fields in transport parameters MUST either be
identical across different QUIC versions, or be unambiguously identical across different QUIC versions, or be unambiguously
different to ensure no confusion about their interpretation. One way different to ensure no confusion about their interpretation. One way
that a new format could be introduced is to define a TLS extension that a new format could be introduced is to define a TLS extension
with a different codepoint. with a different codepoint.
7.5. Stateless Retries 6.5. Stateless Retries
A server can process an initial cryptographic handshake messages from A server can process an initial cryptographic handshake messages from
a client without committing any state. This allows a server to a client without committing any state. This allows a server to
perform address validation (Section 7.6, or to defer connection perform address validation (Section 6.6, or to defer connection
establishment costs. establishment costs.
A server that generates a response to an initial packet without A server that generates a response to an initial packet without
retaining connection state MUST use the Retry packet (Section 5.4.2). retaining connection state MUST use the Retry packet (Section 4.4.2).
This packet causes a client to reset its transport state and to This packet causes a client to reset its transport state and to
continue the connection attempt with new connection state while continue the connection attempt with new connection state while
maintaining the state of the cryptographic handshake. maintaining the state of the cryptographic handshake.
A server MUST NOT send multiple Retry packets in response to a client A server MUST NOT send multiple Retry packets in response to a client
handshake packet. Thus, any cryptographic handshake message that is handshake packet. Thus, any cryptographic handshake message that is
sent MUST fit within a single packet. sent MUST fit within a single packet.
In TLS, the Retry packet type is used to carry the HelloRetryRequest In TLS, the Retry packet type is used to carry the HelloRetryRequest
message. message.
7.6. Proof of Source Address Ownership 6.6. Proof of Source Address Ownership
Transport protocols commonly spend a round trip checking that a Transport protocols commonly spend a round trip checking that a
client owns the transport address (IP and port) that it claims. client owns the transport address (IP and port) that it claims.
Verifying that a client can receive packets sent to its claimed Verifying that a client can receive packets sent to its claimed
transport address protects against spoofing of this information by transport address protects against spoofing of this information by
malicious clients. malicious clients.
This technique is used primarily to avoid QUIC from being used for This technique is used primarily to avoid QUIC from being used for
traffic amplification attack. In such an attack, a packet is sent to traffic amplification attack. In such an attack, a packet is sent to
a server with spoofed source address information that identifies a a server with spoofed source address information that identifies a
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To send additional data prior to completing the cryptographic To send additional data prior to completing the cryptographic
handshake, the server then needs to validate that the client owns the handshake, the server then needs to validate that the client owns the
address that it claims. address that it claims.
Source address validation is therefore performed during the Source address validation is therefore performed during the
establishment of a connection. TLS provides the tools that support establishment of a connection. TLS provides the tools that support
the feature, but basic validation is performed by the core transport the feature, but basic validation is performed by the core transport
protocol. protocol.
A different type of source address validation is performed after a A different type of source address validation is performed after a
connection migration, see Section 7.7.2. connection migration, see Section 6.7.
7.6.1. Client Address Validation Procedure 6.6.1. Client Address Validation Procedure
QUIC uses token-based address validation. Any time the server wishes QUIC uses token-based address validation. Any time the server wishes
to validate a client address, it provides the client with a token. to validate a client address, it provides the client with a token.
As long as the token cannot be easily guessed (see Section 7.6.3), if As long as the token cannot be easily guessed (see Section 6.6.3), if
the client is able to return that token, it proves to the server that the client is able to return that token, it proves to the server that
it received the token. it received the token.
During the processing of the cryptographic handshake messages from a During the processing of the cryptographic handshake messages from a
client, TLS will request that QUIC make a decision about whether to client, TLS will request that QUIC make a decision about whether to
proceed based on the information it has. TLS will provide QUIC with proceed based on the information it has. TLS will provide QUIC with
any token that was provided by the client. For an initial packet, any token that was provided by the client. For an initial packet,
QUIC can decide to abort the connection, allow it to proceed, or QUIC can decide to abort the connection, allow it to proceed, or
request address validation. request address validation.
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asks QUIC a second time whether the token is acceptable. In asks QUIC a second time whether the token is acceptable. In
response, QUIC can either abort the connection or permit it to response, QUIC can either abort the connection or permit it to
proceed. proceed.
A connection MAY be accepted without address validation - or with A connection MAY be accepted without address validation - or with
only limited validation - but a server SHOULD limit the data it sends only limited validation - but a server SHOULD limit the data it sends
toward an unvalidated address. Successful completion of the toward an unvalidated address. Successful completion of the
cryptographic handshake implicitly provides proof that the client has cryptographic handshake implicitly provides proof that the client has
received packets from the server. received packets from the server.
7.6.2. Address Validation on Session Resumption 6.6.2. Address Validation on Session Resumption
A server MAY provide clients with an address validation token during A server MAY provide clients with an address validation token during
one connection that can be used on a subsequent connection. Address one connection that can be used on a subsequent connection. Address
validation is especially important with 0-RTT because a server validation is especially important with 0-RTT because a server
potentially sends a significant amount of data to a client in potentially sends a significant amount of data to a client in
response to 0-RTT data. response to 0-RTT data.
A different type of token is needed when resuming. Unlike the token A different type of token is needed when resuming. Unlike the token
that is created during a handshake, there might be some time between that is created during a handshake, there might be some time between
when the token is created and when the token is subsequently used. when the token is created and when the token is subsequently used.
Thus, a resumption token SHOULD include an expiration time. It is Thus, a resumption token SHOULD include an expiration time. It is
also unlikely that the client port number is the same on two also unlikely that the client port number is the same on two
different connections; validating the port is therefore unlikely to different connections; validating the port is therefore unlikely to
be successful. be successful.
This token can be provided to the cryptographic handshake immediately This token can be provided to the cryptographic handshake immediately
after establishing a connection. QUIC might also generate an updated after establishing a connection. QUIC might also generate an updated
token if significant time passes or the client address changes for token if significant time passes or the client address changes for
any reason (see Section 7.7). The cryptographic handshake is any reason (see Section 6.8). The cryptographic handshake is
responsible for providing the client with the token. In TLS the responsible for providing the client with the token. In TLS the
token is included in the ticket that is used for resumption and token is included in the ticket that is used for resumption and
0-RTT, which is carried in a NewSessionTicket message. 0-RTT, which is carried in a NewSessionTicket message.
7.6.3. Address Validation Token Integrity 6.6.3. Address Validation Token Integrity
An address validation token MUST be difficult to guess. Including a An address validation token MUST be difficult to guess. Including a
large enough random value in the token would be sufficient, but this large enough random value in the token would be sufficient, but this
depends on the server remembering the value it sends to clients. depends on the server remembering the value it sends to clients.
A token-based scheme allows the server to offload any state A token-based scheme allows the server to offload any state
associated with validation to the client. For this design to work, associated with validation to the client. For this design to work,
the token MUST be covered by integrity protection against the token MUST be covered by integrity protection against
modification or falsification by clients. Without integrity modification or falsification by clients. Without integrity
protection, malicious clients could generate or guess values for protection, malicious clients could generate or guess values for
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In TLS the address validation token is often bundled with the In TLS the address validation token is often bundled with the
information that TLS requires, such as the resumption secret. In information that TLS requires, such as the resumption secret. In
this case, adding integrity protection can be delegated to the this case, adding integrity protection can be delegated to the
cryptographic handshake protocol, avoiding redundant protection. If cryptographic handshake protocol, avoiding redundant protection. If
integrity protection is delegated to the cryptographic handshake, an integrity protection is delegated to the cryptographic handshake, an
integrity failure will result in immediate cryptographic handshake integrity failure will result in immediate cryptographic handshake
failure. If integrity protection is performed by QUIC, QUIC MUST failure. If integrity protection is performed by QUIC, QUIC MUST
abort the connection if the integrity check fails with a abort the connection if the integrity check fails with a
PROTOCOL_VIOLATION error code. PROTOCOL_VIOLATION error code.
7.7. Connection Migration 6.7. Path Validation
QUIC connections are identified by their 64-bit Connection ID. Path validation is used by an endpoint to verify reachability of a
QUIC's consistent connection ID allows connections to survive changes peer over a specific path. That is, it tests reachability between a
to the client's IP and/or port, such as those caused by client or specific local address and a specific peer address, where an address
server migrating to a new network. Connection migration allows a is the two-tuple of IP address and port. Path validation tests that
client to retain any shared state with a connection when they move packets can be both sent to and received from a peer.
networks. This includes state that can be hard to recover such as
outstanding requests, which might otherwise be lost with no easy way
to retry them.
An endpoint that receives packets that contain a source IP address Path validation is used during connection migration (see Section 6.8)
and port that has not yet been used can start sending new packets by the migrating endpoint to verify reachability of a peer from a new
with those as a destination IP address and port. Packets exchanged local address. Path validation is also used by the peer to verify
between endpoints can then follow the new path. that the migrating endpoint is able to receive packets sent to its
new address. That is, that the packets received from the migrating
endpoint do not carry a spoofed source address.
Due to variations in path latency or packet reordering, packets from Path validation can be used at any time by either endpoint. For
different source addresses might be reordered. The packet with the instance, an endpoint might check that a peer is still in possession
highest packet number MUST be used to determine which path to use. of its address after a period of quiescence.
Endpoints also need to be prepared to receive packets from an older
source address.
An endpoint MUST validate that its peer can receive packets at the Path validation is not designed as a NAT traversal mechanism. Though
new address before sending any significant quantity of data to that the mechanism described here might be effective for the creation of
address, or it risks being used for denial of service. See NAT bindings that support NAT traversal, the expectation is that one
Section 7.7.2 for details. or other peer is able to receive packets without first having sent a
packet on that path. Effective NAT traversal needs additional
synchronization mechanisms that are not provided here.
7.7.1. Privacy Implications of Connection Migration An endpoint MAY bundle PATH_CHALLENGE and PATH_RESPONSE frames that
are used for path validation with other frames. For instance, an
endpoint may pad a packet carrying a PATH_CHALLENGE for PMTU
discovery, or an endpoint may bundle a PATH_RESPONSE with its own
PATH_CHALLENGE.
Using a stable connection ID on multiple network paths allows a 6.7.1. Initiation
passive observer to correlate activity between those paths. A client
that moves between networks might not wish to have their activity
correlated by any entity other than a server. The NEW_CONNECTION_ID
message can be sent by a server to provide an unlinkable connection
ID for use in case the client wishes to explicitly break linkability
between two points of network attachment.
A client might need to send packets on multiple networks without To initiate path validation, an endpoint sends a PATH_CHALLENGE frame
receiving any response from the server. To ensure that the client is containing a random payload on the path to be validated.
not linkable across each of these changes, a new connection ID and
packet number gap are needed for each network. To support this, a
server sends multiple NEW_CONNECTION_ID messages. Each
NEW_CONNECTION_ID is marked with a sequence number. Connection IDs
MUST be used in the order in which they are numbered.
A client which wishes to break linkability upon changing networks An endpoint MAY send additional PATH_CHALLENGE frames to handle
MUST use the connection ID provided by the server as well as packet loss. An endpoint SHOULD NOT send a PATH_CHALLENGE more
incrementing the packet sequence number by an externally frequently than it would an Initial packet, ensuring that connection
unpredictable value computed as described in Section 7.7.1.1. Packet migration is no more load on a new path than establishing a new
number gaps are cumulative. A client might skip connection IDs, but connection.
it MUST ensure that it applies the associated packet number gaps for
connection IDs that it skips in addition to the packet number gap
associated with the connection ID that it does use.
A server that receives a packet that is marked with a new connection The endpoint MUST use fresh random data in every PATH_CHALLENGE frame
ID recovers the packet number by adding the cumulative packet number so that it can associate the peer's response with the causative
gap to its expected packet number. A server SHOULD discard packets PATH_CHALLENGE.
that contain a smaller gap than it advertised.
For instance, a server might provide a packet number gap of 7 6.7.2. Response
associated with a new connection ID. If the server received packet
10 using the previous connection ID, it should expect packets on the
new connection ID to start at 18. A packet with the new connection
ID and a packet number of 17 is discarded as being in error.
7.7.1.1. Packet Number Gap On receiving a PATH_CHALLENGE frame, an endpoint MUST respond
immediately by echoing the data contained in the PATH_CHALLENGE frame
in a PATH_RESPONSE frame, with the following stipulation. Since a
PATH_CHALLENGE might be sent from a spoofed address, an endpoint MAY
limit the rate at which it sends PATH_RESPONSE frames and MAY
silently discard PATH_CHALLENGE frames that would cause it to respond
at a higher rate.
In order to avoid linkage, the packet number gap MUST be externally To ensure that packets can be both sent to and received from the
indistinguishable from random. The packet number gap for a peer, the PATH_RESPONSE MUST be sent on the same path as the
connection ID with sequence number is computed by encoding the triggering PATH_CHALLENGE: from the same local address on which the
sequence number as a 32-bit integer in big-endian format, and then PATH_CHALLENGE was received, to the same remote address from which
computing: the PATH_CHALLENGE was received.
Gap = HKDF-Expand-Label(packet_number_secret, 6.7.3. Completion
"QUIC packet sequence gap", sequence, 4)
The output of HKDF-Expand-Label is interpreted as a big-endian A new address is considered valid when a PATH_RESPONSE frame is
number. "packet_number_secret" is derived from the TLS key exchange, received containing data that was sent in a previous PATH_CHALLENGE.
as described in Section 5.6 of [QUIC-TLS]. Receipt of an acknowledgment for a packet containing a PATH_CHALLENGE
frame is not adequate validation, since the acknowledgment can be
spoofed by a malicious peer.
7.7.2. Address Validation for Migrated Connections For path validation to be successful, a PATH_RESPONSE frame MUST be
received from the same remote address to which the corresponding
PATH_CHALLENGE was sent. If a PATH_RESPONSE frame is received from a
different remote address than the one to which the PATH_CHALLENGE was
sent, path validation is considered to have failed, even if the data
matches that sent in the PATH_CHALLENGE.
An endpoint that receives a packet from a new remote IP address and Additionally, the PATH_RESPONSE frame MUST be received on the same
port (or just a new remote port) on packets from its peer is likely local address from which the corresponding PATH_CHALLENGE was sent.
seeing a connection migration at the peer. If a PATH_RESPONSE frame is received on a different local address
than the one from which the PATH_CHALLENGE was sent, path validation
is considered to have failed, even if the data matches that sent in
the PATH_CHALLENGE. Thus, the endpoint considers the path to be
valid when a PATH_RESPONSE frame is received on the same path with
the same payload as the PATH_CHALLENGE frame.
However, it is also possible that the peer is spoofing its source 6.7.4. Abandonment
address in order to cause the endpoint to send excessive amounts of
data to an unwilling host. If the endpoint sends significantly more
data than the peer, connection migration might be used to amplify the
volume of data that an attacker can generate toward a victim.
Thus, when seeing a new remote transport address, an endpoint MUST An endpoint SHOULD abandon path validation after sending some number
verify that its peer can receive and respond to packets at that new of PATH_CHALLENGE frames or after some time has passed. When setting
address. By providing copies of the data that it receives, the peer this timer, implementations are cautioned that the new path could
proves that it is receiving packets at the new address and consents have a longer round-trip time than the original.
to receive data.
Prior to validating the new remote address, and endpoint MUST limit Note that the endpoint might receive packets containing other frames
the amount of data and packets that it sends to its peer. At a on the new path, but a PATH_RESPONSE frame with appropriate data is
minimum, this needs to consider the possibility that packets are sent required for path validation to succeed.
without congestion feedback.
Once a connection is established, address validation is relatively If path validation fails, the path is deemed unusable. This does not
simple (see Section 7.6 for the process that is used during the necessarily imply a failure of the connection - endpoints can
handshake). An endpoint validates a remote address by sending a continue sending packets over other paths as appropriate. If no
PATH_CHALLENGE frame containing a payload that is hard to guess. paths are available, an endpoint can wait for a new path to become
This frame MUST be sent in a packet that is sent to the new address. available or close the connection.
Once a PATH_RESPONSE frame containing the same payload is received,
the address is considered to be valid.
The new address is not considered valid until a PATH_RESPONSE frame A path validation might be abandoned for other reasons besides
containing the same payload is received, even if the packet failure. Primarily, this happens if a connection migration to a new
containing the PATH_CHALLENGE frame is acknowledged. path is initiated while a path validation on the old path is in
progress.
The PATH_RESPONSE frame can use any path on its return. 6.8. Connection Migration
An endpoint MAY send multiple PATH_CHALLENGE frames to handle packet QUIC allows connections to survive changes to endpoint addresses
loss or to make additional measurements on a new network path. (that is, IP address and/or port), such as those caused by a endpoint
migrating to a new network. This section describes the process by
which an endpoint migrates to a new address.
An endpoint MUST use fresh random data in every PATH_CHALLENGE frame An endpoint MUST NOT initiate connection migration before the
so that it can associate the peer's response with the causative handshake is finished and the endpoint has 1-RTT keys.
PATH_CHALLENGE.
If the PATH_CHALLENGE frame is determined to be lost, a new This document limits migration of connections to new client
PATH_CHALLENGE frame SHOULD be generated. This PATH_CHALLENGE frame addresses. Clients are responsible for initiating all migrations.
MUST include new data that is similarly difficult to guess. Servers do not send non-probing packets (see Section 6.8.1) toward a
client address until it sees a non-probing packet from that address.
If a client receives packets from an unknown server address, the
client MAY discard these packets. Migrating a connection to a new
server address is left for future work.
If validation of the new remote address fails, after allowing enough 6.8.1. Probing a New Path
time for recovering from possible loss of packets carrying
PATH_CHALLENGE and PATH_RESPONSE frames, the endpoint MUST terminate
the connection. When setting this timer, implementations are
cautioned that the new path could have a longer round trip time than
the original. The endpoint MUST NOT send a CONNECTION_CLOSE frame in
this case; it has to assume that the remote peer cannot want to
receive any more packets.
If the remote address is validated successfully, the endpoint MAY An endpoint MAY probe for peer reachability from a new local address
increase the rate that it sends on the new path using the state from using path validation Section 6.7 prior to migrating the connection
the previous path. The capacity available on the new path might not to the new local address. Failure of path validation simply means
be the same as the old path. An endpoint MUST NOT restore its send that the new path is not usable for this connection. Failure to
rate unless it is reasonably sure that the path is the same as the validate a path does not cause the connection to end unless there are
previous path. For instance, a change in only port number is likely no valid alternative paths available.
indicative of a rebinding in a middlebox and not a complete change in
path. This determination likely depends on heuristics, which could
be imperfect; if the new path capacity is significantly reduced,
ultimately this relies on the congestion controller responding to
congestion signals and reduce send rates appropriately.
After verifying an address, the endpoint SHOULD update any address An endpoint uses a new connection ID for probes sent from a new local
validation tokens (Section 7.6) that it has issued to its peer if address, see Section 6.8.5 for further discussion.
those are no longer valid based on the changed address.
Address validation using the PATH_CHALLENGE frame MAY be used at any Receiving a PATH_CHALLENGE frame from a peer indicates that the peer
time by either peer. For instance, an endpoint might check that a is probing for reachability on a path. An endpoint sends a
peer is still in possession of its address after a period of PATH_RESPONSE in response as per Section 6.7.
quiescence.
Upon seeing a connection migration, an endpoint that sees a new PATH_CHALLENGE, PATH_RESPONSE, and PADDING frames are "probing
address MUST abandon any address validation it is performing with frames", and all other frames are "non-probing frames". A packet
other addresses on the expectation that the validation is likely to containing only probing frames is a "probing packet", and a packet
fail. Abandoning address validation primarily means not closing the containing any other frame is a "non-probing packet".
connection when a PATH_RESPONSE frame is not received, but it could
also mean ceasing subsequent transmissions of the PATH_CHALLENGE
frame. An endpoint MUST ignore any subsequently received
PATH_RESPONSE frames from that address.
7.8. Spurious Connection Migrations 6.8.2. Initiating Connection Migration
A connection migration could be triggered by an attacker that is able A endpoint can migrate a connection to a new local address by sending
to capture and forward a packet such that it arrives before the packets containing frames other than probing frames from that
legitimate copy of that packet. Such a packet will appear to be a address.
legitimate connection migration and the legitimate copy will be
dropped as a duplicate.
After a spurious migration, validation of the source address will Each endpoint validates its peer's address during connection
fail because the entity at the source address does not have the establishment. Therefore, a migrating endpoint can send to its peer
necessary cryptographic keys to read or respond to the PATH_CHALLENGE knowing that the peer is willing to receive at the peer's current
frame that is sent to it, even if it wanted to. Such a spurious address. Thus an endpoint can migrate to a new local address without
connection migration could result in the connection being dropped first validating the peer's address.
when the source address validation fails. This grants an attacker
the ability to terminate the connection.
Receipt of packets with higher packet numbers from the legitimate When migrating, the new path might not support the endpoint's current
address will trigger another connection migration. This will cause sending rate. Therefore, the endpoint resets its congestion
the validation of the address of the spurious migration to be controller, as described in Section 6.8.4.
abandoned.
To ensure that a peer sends packets from the legitimate address Receiving acknowledgments for data sent on the new path serves as
before the validation of the new address can fail, an endpoint SHOULD proof of the peer's reachability from the new address. Note that
attempt to validate the old remote address before attempting to since acknowledgments may be received on any path, return
validate the new address. If the connection migration is spurious, reachability on the new path is not established. To establish return
then the legitimate address will be used to respond and the reachability on the new path, an endpoint MAY concurrently initiate
connection will migrate back to the old address. path validation Section 6.7 on the new path.
As with any address validation, packets containing a PATH_CHALLENGE 6.8.3. Responding to Connection Migration
frame validating an address MUST be sent to the address being
validated. Consequently, during a migration of a peer, an endpoint
could be sending to multiple remote addresses.
An endpoint MAY abandon address validation for an address that it Receiving a packet from a new peer address containing a non-probing
considers to be already valid. That is, if successive connection frame indicates that the peer has migrated to that address.
migrations occur in quick succession with the final remote address
being identical to the initial remote address, the endpoint MAY
abandon address validation for that address.
7.9. Connection Termination In response to such a packet, an endpoint MUST start sending
subsequent packets to the new peer address and MUST initiate path
validation (Section 6.7) to verify the peer's ownership of the
unvalidated address.
An endpoint MAY send data to an unvalidated peer address, but it MUST
protect against potential attacks as described in Section 6.8.3.1 and
Section 6.8.3.2. An endpoint MAY skip validation of a peer address
if that address has been seen recently.
An endpoint only changes the address that it sends packets to in
response to the highest-numbered non-probing packet. This ensures
that an endpoint does not send packets to an old peer address in the
case that it receives reordered packets.
After changing the address to which it sends non-probing packets, an
endpoint could abandon any path validation for other addresses.
Receiving a packet from a new peer address might be the result of a
NAT rebinding at the peer.
After verifying a new client address, the server SHOULD send new
address validation tokens (Section 6.6) to the client.
6.8.3.1. Handling Address Spoofing by a Peer
It is possible that a peer is spoofing its source address to cause an
endpoint to send excessive amounts of data to an unwilling host. If
the endpoint sends significantly more data than the spoofing peer,
connection migration might be used to amplify the volume of data that
an attacker can generate toward a victim.
As described in Section 6.8.3, an endpoint is required to validate a
peer's new address to confirm the peer's possession of the new
address. Until a peer's address is deemed valid, an endpoint MUST
limit the rate at which it sends data to this address. The endpoint
MUST NOT send more than a minimum congestion window's worth of data
per estimated round-trip time (kMinimumWindow, as defined in
[QUIC-RECOVERY]). In the absence of this limit, an endpoint risks
being used for a denial of service attack against an unsuspecting
victim. Note that since the endpoint will not have any round-trip
time measurements to this address, the estimate SHOULD be the default
initial value (see [QUIC-RECOVERY]).
If an endpoint skips validation of a peer address as described in
Section 6.8.3, it does not need to limit its sending rate.
6.8.3.2. Handling Address Spoofing by an On-path Attacker
An on-path attacker could cause a spurious connection migration by
copying and forwarding a packet with a spoofed address such that it
arrives before the original packet. The packet with the spoofed
address will be seen to come from a migrating connection, and the
original packet will be seen as a duplicate and dropped. After a
spurious migration, validation of the source address will fail
because the entity at the source address does not have the necessary
cryptographic keys to read or respond to the PATH_CHALLENGE frame
that is sent to it even if it wanted to.
To protect the connection from failing due to such a spurious
migration, an endpoint MUST revert to using the last validated peer
address when validation of a new peer address fails.
If an endpoint has no state about the last validated peer address, it
MUST close the connection silently by discarding all connection
state. This results in new packets on the connection being handled
generically. For instance, an endpoint MAY send a stateless reset in
response to any further incoming packets.
Note that receipt of packets with higher packet numbers from the
legitimate peer address will trigger another connection migration.
This will cause the validation of the address of the spurious
migration to be abandoned.
6.8.4. Loss Detection and Congestion Control
The capacity available on the new path might not be the same as the
old path. Packets sent on the old path SHOULD NOT contribute to
congestion control or RTT estimation for the new path.
On confirming a peer's ownership of its new address, an endpoint
SHOULD immediately reset the congestion controller and round-trip
time estimator for the new path.
An endpoint MUST NOT return to the send rate used for the previous
path unless it is reasonably sure that the previous send rate is
valid for the new path. For instance, a change in the client's port
number is likely indicative of a rebinding in a middlebox and not a
complete change in path. This determination likely depends on
heuristics, which could be imperfect; if the new path capacity is
significantly reduced, ultimately this relies on the congestion
controller responding to congestion signals and reducing send rates
appropriately.
There may be apparent reordering at the receiver when an endpoint
sends data and probes from/to multiple addresses during the migration
period, since the two resulting paths may have different round-trip
times. A receiver of packets on multiple paths will still send ACK
frames covering all received packets.
While multiple paths might be used during connection migration, a
single congestion control context and a single loss recovery context
(as described in [QUIC-RECOVERY]) may be adequate. A sender can make
exceptions for probe packets so that their loss detection is
independent and does not unduly cause the congestion controller to
reduce its sending rate. An endpoint might arm a separate alarm when
a PATH_CHALLENGE is sent, which is disarmed when the corresponding
PATH_RESPONSE is received. If the alarm fires before the
PATH_RESPONSE is received, the endpoint might send a new
PATH_CHALLENGE, and restart the alarm for a longer period of time.
6.8.5. Privacy Implications of Connection Migration
Using a stable connection ID on multiple network paths allows a
passive observer to correlate activity between those paths. An
endpoint that moves between networks might not wish to have their
activity correlated by any entity other than a server. The
NEW_CONNECTION_ID message can be sent by both endpoints to provide an
unlinkable connection ID for use in case a peer wishes to explicitly
break linkability between two points of network attachment.
An endpoint might need to send packets on multiple networks without
receiving any response from its peer. To ensure that the endpoint is
not linkable across each of these changes, a new connection ID and
packet number gap are needed for each network. To support this, each
endpoint sends multiple NEW_CONNECTION_ID messages. Each
NEW_CONNECTION_ID is marked with a sequence number. Connection IDs
MUST be used in the order in which they are numbered.
An endpoint that does not require the use of a connection ID should
not request that its peer use a connection ID. Such an endpoint does
not need to provide new connection IDs using the NEW_CONNECTION_ID
frame.
An endpoint which wishes to break linkability upon changing networks
MUST use the connection ID provided by its peer as well as
incrementing the packet sequence number by an externally
unpredictable value computed as described in Section 6.8.5.1. Packet
number gaps are cumulative. An endpoint might skip connection IDs,
but it MUST ensure that it applies the associated packet number gaps
for connection IDs that it skips in addition to the packet number gap
associated with the connection ID that it does use.
An endpoint that receives a packet that is marked with a new
connection ID recovers the packet number by adding the cumulative
packet number gap to its expected packet number. An endpoint MUST
discard packets that contain a smaller gap than it advertised.
Clients MAY change connection ID at any time based on implementation-
specific concerns. For example, after a period of network inactivity
NAT rebinding might occur when the client begins sending data again.
A client might wish to reduce linkability by employing a new
connection ID and source UDP port when sending traffic after a period
of inactivity. Changing the UDP port from which it sends packets at
the same time might cause the packet to appear as a connection
migration. This ensures that the mechanisms that support migration
are exercised even for clients that don't experience NAT rebindings
or genuine migrations. Changing port number can cause a peer to
reset its congestion state (see Section 6.8.4), so the port SHOULD
only be changed infrequently.
An endpoint that receives a successfully authenticated packet with a
previously unused connection ID MUST use the next available
connection ID for any packets it sends to that address. To avoid
changing connection IDs multiple times when packets arrive out of
order, endpoints MUST change only in response to a packet that
increases the largest received packet number. Failing to do this
could allow for use of that connection ID to link activity on new
paths. There is no need to move to a new connection ID if the
address of a peer changes without also changing the connection ID.
For instance, a server might provide a packet number gap of 7
associated with a new connection ID. If the server received packet
10 using the previous connection ID, it should expect packets on the
new connection ID to start at 18. A packet with the new connection
ID and a packet number of 17 is discarded as being in error.
6.8.5.1. Packet Number Gap
In order to avoid linkage, the packet number gap MUST be externally
indistinguishable from random. The packet number gap for a
connection ID with sequence number is computed by encoding the
sequence number as a 32-bit integer in big-endian format, and then
computing:
Gap = HKDF-Expand-Label(packet_number_secret,
"QUIC packet sequence gap", sequence, 4)
The output of HKDF-Expand-Label is interpreted as a big-endian
number. "packet_number_secret" is derived from the TLS key exchange,
as described in Section 5.6 of [QUIC-TLS].
6.9. Connection Termination
Connections should remain open until they become idle for a pre- Connections should remain open until they become idle for a pre-
negotiated period of time. A QUIC connection, once established, can negotiated period of time. A QUIC connection, once established, can
be terminated in one of three ways: be terminated in one of three ways:
o idle timeout (Section 7.9.2) o idle timeout (Section 6.9.2)
o immediate close (Section 6.9.3)
o immediate close (Section 7.9.3)
o stateless reset (Section 7.9.4) o stateless reset (Section 6.9.4)
7.9.1. Closing and Draining Connection States 6.9.1. Closing and Draining Connection States
The closing and draining connection states exist to ensure that The closing and draining connection states exist to ensure that
connections close cleanly and that delayed or reordered packets are connections close cleanly and that delayed or reordered packets are
properly discarded. These states SHOULD persist for three times the properly discarded. These states SHOULD persist for three times the
current Retransmission Timeout (RTO) interval as defined in current Retransmission Timeout (RTO) interval as defined in
[QUIC-RECOVERY]. [QUIC-RECOVERY].
An endpoint enters a closing period after initiating an immediate An endpoint enters a closing period after initiating an immediate
close (Section 7.9.3) and optionally after an idle timeout close (Section 6.9.3). While closing, an endpoint MUST NOT send
(Section 7.9.2). While closing, an endpoint MUST NOT send packets packets unless they contain a CONNECTION_CLOSE or APPLICATION_CLOSE
unless they contain a CONNECTION_CLOSE or APPLICATION_CLOSE frame frame (see Section 6.9.3 for details).
(see Section 7.9.3 for details).
In the closing state, only a packet containing a closing frame can be In the closing state, only a packet containing a closing frame can be
sent. An endpoint retains only enough information to generate a sent. An endpoint retains only enough information to generate a
packet containing a closing frame and to identify packets as packet containing a closing frame and to identify packets as
belonging to the connection. The connection ID and QUIC version is belonging to the connection. The connection ID and QUIC version is
sufficient information to identify packets for a closing connection; sufficient information to identify packets for a closing connection;
an endpoint can discard all other connection state. An endpoint MAY an endpoint can discard all other connection state. An endpoint MAY
retain packet protection keys for incoming packets to allow it to retain packet protection keys for incoming packets to allow it to
read and process a closing frame. read and process a closing frame.
skipping to change at page 41, line 20 skipping to change at page 45, line 11
an abbreviated draining period which can allow for faster resource an abbreviated draining period which can allow for faster resource
recovery. Servers that retain an open socket for accepting new recovery. Servers that retain an open socket for accepting new
connections SHOULD NOT exit the closing or draining period early. connections SHOULD NOT exit the closing or draining period early.
Once the closing or draining period has ended, an endpoint SHOULD Once the closing or draining period has ended, an endpoint SHOULD
discard all connection state. This results in new packets on the discard all connection state. This results in new packets on the
connection being handled generically. For instance, an endpoint MAY connection being handled generically. For instance, an endpoint MAY
send a stateless reset in response to any further incoming packets. send a stateless reset in response to any further incoming packets.
The draining and closing periods do not apply when a stateless reset The draining and closing periods do not apply when a stateless reset
(Section 7.9.4) is sent. (Section 6.9.4) is sent.
An endpoint is not expected to handle key updates when it is closing An endpoint is not expected to handle key updates when it is closing
or draining. A key update might prevent the endpoint from moving or draining. A key update might prevent the endpoint from moving
from the closing state to draining, but it otherwise has no impact. from the closing state to draining, but it otherwise has no impact.
An endpoint could receive packets from a new source address, An endpoint could receive packets from a new source address,
indicating a connection migration (Section 7.7), while in the closing indicating a client connection migration (Section 6.8), while in the
period. An endpoint in the closing state MUST strictly limit the closing period. An endpoint in the closing state MUST strictly limit
number of packets it sends to this new address as though the address the number of packets it sends to this new address until the address
were not validated (see Section 7.7.2). A server in the closing is validated (see Section 6.7). A server in the closing state MAY
state MAY instead choose to discard packets received from a new instead choose to discard packets received from a new source address.
source address.
7.9.2. Idle Timeout 6.9.2. Idle Timeout
A connection that remains idle for longer than the idle timeout (see A connection that remains idle for longer than the idle timeout (see
Section 7.4.1) is closed. A connection enters the draining state Section 6.4.1) is closed. A connection enters the draining state
when the idle timeout expires. when the idle timeout expires.
The time at which an idle timeout takes effect won't be perfectly The time at which an idle timeout takes effect won't be perfectly
synchronized on both endpoints. An endpoint that sends packets near synchronized on both endpoints. An endpoint that sends packets near
the end of an idle period could have those packets discarded if its the end of an idle period could have those packets discarded if its
peer enters the draining state before the packet is received. peer enters the draining state before the packet is received.
7.9.3. Immediate Close 6.9.3. Immediate Close
An endpoint sends a closing frame, either CONNECTION_CLOSE or An endpoint sends a closing frame, either CONNECTION_CLOSE or
APPLICATION_CLOSE, to terminate the connection immediately. Either APPLICATION_CLOSE, to terminate the connection immediately. Either
closing frame causes all streams to immediately become closed; open closing frame causes all streams to immediately become closed; open
streams can be assumed to be implicitly reset. streams can be assumed to be implicitly reset.
After sending a closing frame, endpoints immediately enter the After sending a closing frame, endpoints immediately enter the
closing state. During the closing period, an endpoint that sends a closing state. During the closing period, an endpoint that sends a
closing frame SHOULD respond to any packet that it receives with closing frame SHOULD respond to any packet that it receives with
another packet containing a closing frame. To minimize the state another packet containing a closing frame. To minimize the state
skipping to change at page 42, line 40 skipping to change at page 46, line 29
An immediate close can be used after an application protocol has An immediate close can be used after an application protocol has
arranged to close a connection. This might be after the application arranged to close a connection. This might be after the application
protocols negotiates a graceful shutdown. The application protocol protocols negotiates a graceful shutdown. The application protocol
exchanges whatever messages that are needed to cause both endpoints exchanges whatever messages that are needed to cause both endpoints
to agree to close the connection, after which the application to agree to close the connection, after which the application
requests that the connection be closed. The application protocol can requests that the connection be closed. The application protocol can
use an APPLICATION_CLOSE message with an appropriate error code to use an APPLICATION_CLOSE message with an appropriate error code to
signal closure. signal closure.
7.9.4. Stateless Reset 6.9.4. Stateless Reset
A stateless reset is provided as an option of last resort for a A stateless reset is provided as an option of last resort for a
server that does not have access to the state of a connection. A server that does not have access to the state of a connection. A
server crash or outage might result in clients continuing to send server crash or outage might result in clients continuing to send
data to a server that is unable to properly continue the connection. data to a server that is unable to properly continue the connection.
A server that wishes to communicate a fatal connection error MUST use A server that wishes to communicate a fatal connection error MUST use
a closing frame if it has sufficient state to do so. a closing frame if it has sufficient state to do so.
To support this process, the server sends a stateless_reset_token To support this process, the server sends a stateless_reset_token
value during the handshake in the transport parameters. This value value during the handshake in the transport parameters. This value
is protected by encryption, so only client and server know this is protected by encryption, so only client and server know this
value. value.
A server that receives packets that it cannot process sends a packet A server that receives packets that it cannot process sends a packet
in the following layout: in the following layout:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|0|C|K|Type (5) | |0|K| Type (6) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | Destination Connection ID (144) ...
+ [Connection ID (64)] +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packet Number (8/16/32) | | Packet Number (8/16/32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Random Octets (*) ... | Random Octets (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ Stateless Reset Token (128) + + Stateless Reset Token (128) +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A server copies the connection ID field from the packet that triggers This design ensures that a stateless reset packet is - to the extent
the stateless reset. A server omits the connection ID if explicitly possible - indistinguishable from a regular packet with a short
configured to do so, or if the client packet did not include a header.
connection ID.
A server generates a random 18-octet Destination Connection ID field.
For a client that depends on the server including a connection ID,
this will mean that this value differs from previous packets. Ths
results in two problems:
o The packet might not reach the client. If the Destination
Connection ID is critical for routing toward the client, then this
packet could be incorrectly routed. This causes the stateless
reset to be ineffective in causing errors to be quickly detected
and recovered. In this case, clients will need to rely on other
methods - such as timers - to detect that the connection has
failed.
o The randomly generated connection ID can be used by entities other
than the client to identify this as a potential stateless reset.
A server that occasionally uses different connection IDs might
introduce some uncertainty about this.
The Packet Number field is set to a randomized value. The server The Packet Number field is set to a randomized value. The server
SHOULD send a packet with a short header and a type of 0x1F. This SHOULD send a packet with a short header and a type of 0x1F. This
produces the shortest possible packet number encoding, which produces the shortest possible packet number encoding, which
minimizes the perceived gap between the last packet that the server minimizes the perceived gap between the last packet that the server
sent and this packet. A server MAY use a different short header sent and this packet. A server MAY use a different short header
type, indicating a different packet number length, but a longer type, indicating a different packet number length, but a longer
packet number encoding might allow this message to be identified as a packet number encoding might allow this message to be identified as a
stateless reset more easily using heuristics. stateless reset more easily using heuristics.
After the Packet Number, the server pads the message with an After the Packet Number, the server pads the message with an
arbitrary number of octets containing random values. arbitrary number of octets containing random values.
Finally, the last 16 octets of the packet are set to the value of the Finally, the last 16 octets of the packet are set to the value of the
Stateless Reset Token. Stateless Reset Token.
This design ensures that a stateless reset packet is - to the extent
possible - indistinguishable from a regular packet.
A stateless reset is not appropriate for signaling error conditions. A stateless reset is not appropriate for signaling error conditions.
An endpoint that wishes to communicate a fatal connection error MUST An endpoint that wishes to communicate a fatal connection error MUST
use a CONNECTION_CLOSE or APPLICATION_CLOSE frame if it has use a CONNECTION_CLOSE or APPLICATION_CLOSE frame if it has
sufficient state to do so. sufficient state to do so.
This stateless reset design is specific to QUIC version 1. A server This stateless reset design is specific to QUIC version 1. A server
that supports multiple versions of QUIC needs to generate a stateless that supports multiple versions of QUIC needs to generate a stateless
reset that will be accepted by clients that support any version that reset that will be accepted by clients that support any version that
the server might support (or might have supported prior to losing the server might support (or might have supported prior to losing
state). Designers of new versions of QUIC need to be aware of this state). Designers of new versions of QUIC need to be aware of this
and either reuse this design, or use a portion of the packet other and either reuse this design, or use a portion of the packet other
than the last 16 octets for carrying data. than the last 16 octets for carrying data.
7.9.4.1. Detecting a Stateless Reset 6.9.4.1. Detecting a Stateless Reset
A client detects a potential stateless reset when a packet with a A client detects a potential stateless reset when a packet with a
short header either cannot be decrypted or is marked as a duplicate short header either cannot be decrypted or is marked as a duplicate
packet. The client then compares the last 16 octets of the packet packet. The client then compares the last 16 octets of the packet
with the Stateless Reset Token provided by the server in its with the Stateless Reset Token provided by the server in its
transport parameters. If these values are identical, the client MUST transport parameters. If these values are identical, the client MUST
enter the draining period and not send any further packets on this enter the draining period and not send any further packets on this
connection. If the comparison fails, the packet can be discarded. connection. If the comparison fails, the packet can be discarded.
7.9.4.2. Calculating a Stateless Reset Token 6.9.4.2. Calculating a Stateless Reset Token
The stateless reset token MUST be difficult to guess. In order to The stateless reset token MUST be difficult to guess. In order to
create a Stateless Reset Token, a server could randomly generate create a Stateless Reset Token, a server could randomly generate
[RFC4086] a secret for every connection that it creates. However, [RFC4086] a secret for every connection that it creates. However,
this presents a coordination problem when there are multiple servers this presents a coordination problem when there are multiple servers
in a cluster or a storage problem for a server that might lose state. in a cluster or a storage problem for a server that might lose state.
Stateless reset specifically exists to handle the case where state is Stateless reset specifically exists to handle the case where state is
lost, so this approach is suboptimal. lost, so this approach is suboptimal.
A single static key can be used across all connections to the same A single static key can be used across all connections to the same
endpoint by generating the proof using a second iteration of a endpoint by generating the proof using a second iteration of a
preimage-resistant function that takes three inputs: the static key, preimage-resistant function that takes three inputs: the static key,
a the connection ID for the connection (see Section 5.6), and an the server's connection ID (see Section 4.7), and an identifier for
identifier for the server instance. A server could use HMAC the server instance. A server could use HMAC [RFC2104] (for example,
[RFC2104] (for example, HMAC(static_key, server_id || connection_id)) HMAC(static_key, server_id || connection_id)) or HKDF [RFC5869] (for
or HKDF [RFC5869] (for example, using the static key as input keying example, using the static key as input keying material, with server
material, with server and connection identifiers as salt). The and connection identifiers as salt). The output of this function is
output of this function is truncated to 16 octets to produce the truncated to 16 octets to produce the Stateless Reset Token for that
Stateless Reset Token for that connection. connection.
A server that loses state can use the same method to generate a valid A server that loses state can use the same method to generate a valid
Stateless Reset Secret. The connection ID comes from the packet that Stateless Reset Secret. The connection ID comes from the packet that
the server receives. the server receives.
This design relies on the client always sending a connection ID in This design relies on the client always sending a connection ID in
its packets so that the server can use the connection ID from a its packets so that the server can use the connection ID from a
packet to reset the connection. A server that uses this design packet to reset the connection. A server that uses this design
cannot allow clients to omit a connection ID (that is, it cannot use cannot allow clients to use a zero-length connection ID.
the truncate_connection_id transport parameter Section 7.4.1).
Revealing the Stateless Reset Token allows any entity to terminate Revealing the Stateless Reset Token allows any entity to terminate
the connection, so a value can only be used once. This method for the connection, so a value can only be used once. This method for
choosing the Stateless Reset Token means that the combination of choosing the Stateless Reset Token means that the combination of
server instance, connection ID, and static key cannot occur for server instance, connection ID, and static key cannot occur for
another connection. A connection ID from a connection that is reset another connection. A connection ID from a connection that is reset
by revealing the Stateless Reset Token cannot be reused for new by revealing the Stateless Reset Token cannot be reused for new
connections at the same server without first changing to use a connections at the same server without first changing to use a
different static key or server identifier. different static key or server identifier.
Note that Stateless Reset messages do not have any cryptographic Note that Stateless Reset messages do not have any cryptographic
protection. protection.
8. Frame Types and Formats 7. Frame Types and Formats
As described in Section 6, packets contain one or more frames. This As described in Section 5, packets contain one or more frames. This
section describes the format and semantics of the core QUIC frame section describes the format and semantics of the core QUIC frame
types. types.
8.1. Variable-Length Integer Encoding 7.1. Variable-Length Integer Encoding
QUIC frames use a common variable-length encoding for all non- QUIC frames use a common variable-length encoding for all non-
negative integer values. This encoding ensures that smaller integer negative integer values. This encoding ensures that smaller integer
values need fewer octets to encode. values need fewer octets to encode.
The QUIC variable-length integer encoding reserves the two most The QUIC variable-length integer encoding reserves the two most
significant bits of the first octet to encode the base 2 logarithm of significant bits of the first octet to encode the base 2 logarithm of
the integer encoding length in octets. The integer value is encoded the integer encoding length in octets. The integer value is encoded
on the remaining bits, in network byte order. on the remaining bits, in network byte order.
skipping to change at page 46, line 25 skipping to change at page 50, line 25
+------+--------+-------------+-----------------------+ +------+--------+-------------+-----------------------+
Table 4: Summary of Integer Encodings Table 4: Summary of Integer Encodings
For example, the eight octet sequence c2 19 7c 5e ff 14 e8 8c (in For example, the eight octet sequence c2 19 7c 5e ff 14 e8 8c (in
hexadecimal) decodes to the decimal value 151288809941952652; the hexadecimal) decodes to the decimal value 151288809941952652; the
four octet sequence 9d 7f 3e 7d decodes to 494878333; the two octet four octet sequence 9d 7f 3e 7d decodes to 494878333; the two octet
sequence 7b bd decodes to 15293; and the single octet 25 decodes to sequence 7b bd decodes to 15293; and the single octet 25 decodes to
37 (as does the two octet sequence 40 25). 37 (as does the two octet sequence 40 25).
Error codes (Section 12.3) are described using integers, but do not Error codes (Section 11.3) are described using integers, but do not
use this encoding. use this encoding.
8.2. PADDING Frame 7.2. PADDING Frame
The PADDING frame (type=0x00) has no semantic value. PADDING frames The PADDING frame (type=0x00) has no semantic value. PADDING frames
can be used to increase the size of a packet. Padding can be used to can be used to increase the size of a packet. Padding can be used to
increase an initial client packet to the minimum required size, or to increase an initial client packet to the minimum required size, or to
provide protection against traffic analysis for protected packets. provide protection against traffic analysis for protected packets.
A PADDING frame has no content. That is, a PADDING frame consists of A PADDING frame has no content. That is, a PADDING frame consists of
the single octet that identifies the frame as a PADDING frame. the single octet that identifies the frame as a PADDING frame.
8.3. RST_STREAM Frame 7.3. RST_STREAM Frame
An endpoint may use a RST_STREAM frame (type=0x01) to abruptly An endpoint may use a RST_STREAM frame (type=0x01) to abruptly
terminate a stream. terminate a stream.
After sending a RST_STREAM, an endpoint ceases transmission and After sending a RST_STREAM, an endpoint ceases transmission and
retransmission of STREAM frames on the identified stream. A receiver retransmission of STREAM frames on the identified stream. A receiver
of RST_STREAM can discard any data that it already received on that of RST_STREAM can discard any data that it already received on that
stream. stream.
An endpoint that receives a RST_STREAM frame for a send-only stream An endpoint that receives a RST_STREAM frame for a send-only stream
skipping to change at page 47, line 21 skipping to change at page 51, line 21
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Final Offset (i) ... | Final Offset (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are: The fields are:
Stream ID: A variable-length integer encoding of the Stream ID of Stream ID: A variable-length integer encoding of the Stream ID of
the stream being terminated. the stream being terminated.
Application Protocol Error Code: A 16-bit application protocol error Application Protocol Error Code: A 16-bit application protocol error
code (see Section 12.4) which indicates why the stream is being code (see Section 11.4) which indicates why the stream is being
closed. closed.
Final Offset: A variable-length integer indicating the absolute byte Final Offset: A variable-length integer indicating the absolute byte
offset of the end of data written on this stream by the RST_STREAM offset of the end of data written on this stream by the RST_STREAM
sender. sender.
8.4. CONNECTION_CLOSE frame 7.4. CONNECTION_CLOSE frame
An endpoint sends a CONNECTION_CLOSE frame (type=0x02) to notify its An endpoint sends a CONNECTION_CLOSE frame (type=0x02) to notify its
peer that the connection is being closed. CONNECTION_CLOSE is used peer that the connection is being closed. CONNECTION_CLOSE is used
to signal errors at the QUIC layer, or the absence of errors (with to signal errors at the QUIC layer, or the absence of errors (with
the NO_ERROR code). the NO_ERROR code).
If there are open streams that haven't been explicitly closed, they If there are open streams that haven't been explicitly closed, they
are implicitly closed when the connection is closed. are implicitly closed when the connection is closed.
The CONNECTION_CLOSE frame is as follows: The CONNECTION_CLOSE frame is as follows:
skipping to change at page 48, line 4 skipping to change at page 52, line 4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Code (16) | Reason Phrase Length (i) ... | Error Code (16) | Reason Phrase Length (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reason Phrase (*) ... | Reason Phrase (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields of a CONNECTION_CLOSE frame are as follows: The fields of a CONNECTION_CLOSE frame are as follows:
Error Code: A 16-bit error code which indicates the reason for Error Code: A 16-bit error code which indicates the reason for
closing this connection. CONNECTION_CLOSE uses codes from the closing this connection. CONNECTION_CLOSE uses codes from the
space defined in Section 12.3 (APPLICATION_CLOSE uses codes from space defined in Section 11.3 (APPLICATION_CLOSE uses codes from
the application protocol error code space, see Section 12.4). the application protocol error code space, see Section 11.4).
Reason Phrase Length: A variable-length integer specifying the Reason Phrase Length: A variable-length integer specifying the
length of the reason phrase in bytes. Note that a length of the reason phrase in bytes. Note that a
CONNECTION_CLOSE frame cannot be split between packets, so in CONNECTION_CLOSE frame cannot be split between packets, so in
practice any limits on packet size will also limit the space practice any limits on packet size will also limit the space
available for a reason phrase. available for a reason phrase.
Reason Phrase: A human-readable explanation for why the connection Reason Phrase: A human-readable explanation for why the connection
was closed. This can be zero length if the sender chooses to not was closed. This can be zero length if the sender chooses to not
give details beyond the Error Code. This SHOULD be a UTF-8 give details beyond the Error Code. This SHOULD be a UTF-8
encoded string [RFC3629]. encoded string [RFC3629].
8.5. APPLICATION_CLOSE frame 7.5. APPLICATION_CLOSE frame
An APPLICATION_CLOSE frame (type=0x03) uses the same format as the An APPLICATION_CLOSE frame (type=0x03) uses the same format as the
CONNECTION_CLOSE frame (Section 8.4), except that it uses error codes CONNECTION_CLOSE frame (Section 7.4), except that it uses error codes
from the application protocol error code space (Section 12.4) instead from the application protocol error code space (Section 11.4) instead
of the transport error code space. of the transport error code space.
Other than the error code space, the format and semantics of the Other than the error code space, the format and semantics of the
APPLICATION_CLOSE frame are identical to the CONNECTION_CLOSE frame. APPLICATION_CLOSE frame are identical to the CONNECTION_CLOSE frame.
8.6. MAX_DATA Frame 7.6. MAX_DATA Frame
The MAX_DATA frame (type=0x04) is used in flow control to inform the The MAX_DATA frame (type=0x04) is used in flow control to inform the
peer of the maximum amount of data that can be sent on the connection peer of the maximum amount of data that can be sent on the connection
as a whole. as a whole.
The frame is as follows: The frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 49, line 7 skipping to change at page 53, line 7
amount of data that can be sent on the entire connection, in units amount of data that can be sent on the entire connection, in units
of octets. of octets.
All data sent in STREAM frames counts toward this limit, with the All data sent in STREAM frames counts toward this limit, with the
exception of data on stream 0. The sum of the largest received exception of data on stream 0. The sum of the largest received
offsets on all streams - including streams in terminal states, but offsets on all streams - including streams in terminal states, but
excluding stream 0 - MUST NOT exceed the value advertised by a excluding stream 0 - MUST NOT exceed the value advertised by a
receiver. An endpoint MUST terminate a connection with a receiver. An endpoint MUST terminate a connection with a
QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA error if it receives more QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA error if it receives more
data than the maximum data value that it has sent, unless this is a data than the maximum data value that it has sent, unless this is a
result of a change in the initial limits (see Section 7.4.2). result of a change in the initial limits (see Section 6.4.2).
8.7. MAX_STREAM_DATA Frame 7.7. MAX_STREAM_DATA Frame
The MAX_STREAM_DATA frame (type=0x05) is used in flow control to The MAX_STREAM_DATA frame (type=0x05) is used in flow control to
inform a peer of the maximum amount of data that can be sent on a inform a peer of the maximum amount of data that can be sent on a
stream. stream.
An endpoint that receives a MAX_STREAM_DATA frame for a receive-only An endpoint that receives a MAX_STREAM_DATA frame for a receive-only
stream MUST terminate the connection with error PROTOCOL_VIOLATION. stream MUST terminate the connection with error PROTOCOL_VIOLATION.
An endpoint that receives a MAX_STREAM_DATA frame for a send-only An endpoint that receives a MAX_STREAM_DATA frame for a send-only
stream it has not opened MUST terminate the connection with error stream it has not opened MUST terminate the connection with error
skipping to change at page 50, line 10 skipping to change at page 54, line 10
stream. Loss or reordering can mean that the largest received offset stream. Loss or reordering can mean that the largest received offset
on a stream can be greater than the total size of data received on on a stream can be greater than the total size of data received on
that stream. Receiving STREAM frames might not increase the largest that stream. Receiving STREAM frames might not increase the largest
received offset. received offset.
The data sent on a stream MUST NOT exceed the largest maximum stream The data sent on a stream MUST NOT exceed the largest maximum stream
data value advertised by the receiver. An endpoint MUST terminate a data value advertised by the receiver. An endpoint MUST terminate a
connection with a FLOW_CONTROL_ERROR error if it receives more data connection with a FLOW_CONTROL_ERROR error if it receives more data
than the largest maximum stream data that it has sent for the than the largest maximum stream data that it has sent for the
affected stream, unless this is a result of a change in the initial affected stream, unless this is a result of a change in the initial
limits (see Section 7.4.2). limits (see Section 6.4.2).
8.8. MAX_STREAM_ID Frame 7.8. MAX_STREAM_ID Frame
The MAX_STREAM_ID frame (type=0x06) informs the peer of the maximum The MAX_STREAM_ID frame (type=0x06) informs the peer of the maximum
stream ID that they are permitted to open. stream ID that they are permitted to open.
The frame is as follows: The frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Stream ID (i) ... | Maximum Stream ID (i) ...
skipping to change at page 50, line 43 skipping to change at page 54, line 43
Loss or reordering can mean that a MAX_STREAM_ID frame can be Loss or reordering can mean that a MAX_STREAM_ID frame can be
received which states a lower stream limit than the client has received which states a lower stream limit than the client has
previously received. MAX_STREAM_ID frames which do not increase the previously received. MAX_STREAM_ID frames which do not increase the
maximum stream ID MUST be ignored. maximum stream ID MUST be ignored.
A peer MUST NOT initiate a stream with a higher stream ID than the A peer MUST NOT initiate a stream with a higher stream ID than the
greatest maximum stream ID it has received. An endpoint MUST greatest maximum stream ID it has received. An endpoint MUST
terminate a connection with a STREAM_ID_ERROR error if a peer terminate a connection with a STREAM_ID_ERROR error if a peer
initiates a stream with a higher stream ID than it has sent, unless initiates a stream with a higher stream ID than it has sent, unless
this is a result of a change in the initial limits (see this is a result of a change in the initial limits (see
Section 7.4.2). Section 6.4.2).
8.9. PING Frame 7.9. PING Frame
Endpoints can use PING frames (type=0x07) to verify that their peers Endpoints can use PING frames (type=0x07) to verify that their peers
are still alive or to check reachability to the peer. The PING frame are still alive or to check reachability to the peer. The PING frame
contains no additional fields. contains no additional fields.
The receiver of a PING frame simply needs to acknowledge the packet The receiver of a PING frame simply needs to acknowledge the packet
containing this frame. containing this frame.
The PING frame can be used to keep a connection alive when an The PING frame can be used to keep a connection alive when an
application or application protocol wishes to prevent the connection application or application protocol wishes to prevent the connection
from timing out. An application protocol SHOULD provide guidance from timing out. An application protocol SHOULD provide guidance
about the conditions under which generating a PING is recommended. about the conditions under which generating a PING is recommended.
This guidance SHOULD indicate whether it is the client or the server This guidance SHOULD indicate whether it is the client or the server
that is expected to send the PING. Having both endpoints send PING that is expected to send the PING. Having both endpoints send PING
frames without coordination can produce an excessive number of frames without coordination can produce an excessive number of
packets and poor performance. packets and poor performance.
A connection will time out if no packets are sent or received for a A connection will time out if no packets are sent or received for a
period longer than the time specified in the idle_timeout transport period longer than the time specified in the idle_timeout transport
parameter (see Section 7.9). However, state in middleboxes might parameter (see Section 6.9). However, state in middleboxes might
time out earlier than that. Though REQ-5 in [RFC4787] recommends a 2 time out earlier than that. Though REQ-5 in [RFC4787] recommends a 2
minute timeout interval, experience shows that sending packets every minute timeout interval, experience shows that sending packets every
15 to 30 seconds is necessary to prevent the majority of middleboxes 15 to 30 seconds is necessary to prevent the majority of middleboxes
from losing state for UDP flows. from losing state for UDP flows.
8.10. BLOCKED Frame 7.10. BLOCKED Frame
A sender SHOULD send a BLOCKED frame (type=0x08) when it wishes to A sender SHOULD send a BLOCKED frame (type=0x08) when it wishes to
send data, but is unable to due to connection-level flow control (see send data, but is unable to due to connection-level flow control (see
Section 11.2.1). BLOCKED frames can be used as input to tuning of Section 10.2.1). BLOCKED frames can be used as input to tuning of
flow control algorithms (see Section 11.1.2). flow control algorithms (see Section 10.1.2).
The BLOCKED frame is as follows: The BLOCKED frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Offset (i) ... | Offset (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The BLOCKED frame contains a single field. The BLOCKED frame contains a single field.
Offset: A variable-length integer indicating the connection-level Offset: A variable-length integer indicating the connection-level
offset at which the blocking occurred. offset at which the blocking occurred.
8.11. STREAM_BLOCKED Frame 7.11. STREAM_BLOCKED Frame
A sender SHOULD send a STREAM_BLOCKED frame (type=0x09) when it A sender SHOULD send a STREAM_BLOCKED frame (type=0x09) when it
wishes to send data, but is unable to due to stream-level flow wishes to send data, but is unable to due to stream-level flow
control. This frame is analogous to BLOCKED (Section 8.10). control. This frame is analogous to BLOCKED (Section 7.10).
An endpoint that receives a STREAM_BLOCKED frame for a send-only An endpoint that receives a STREAM_BLOCKED frame for a send-only
stream MUST terminate the connection with error PROTOCOL_VIOLATION. stream MUST terminate the connection with error PROTOCOL_VIOLATION.
The STREAM_BLOCKED frame is as follows: The STREAM_BLOCKED frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (i) ... | Stream ID (i) ...
skipping to change at page 52, line 21 skipping to change at page 56, line 21
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The STREAM_BLOCKED frame contains two fields: The STREAM_BLOCKED frame contains two fields:
Stream ID: A variable-length integer indicating the stream which is Stream ID: A variable-length integer indicating the stream which is
flow control blocked. flow control blocked.
Offset: A variable-length integer indicating the offset of the Offset: A variable-length integer indicating the offset of the
stream at which the blocking occurred. stream at which the blocking occurred.
8.12. STREAM_ID_BLOCKED Frame 7.12. STREAM_ID_BLOCKED Frame
A sender MAY send a STREAM_ID_BLOCKED frame (type=0x0a) when it A sender MAY send a STREAM_ID_BLOCKED frame (type=0x0a) when it
wishes to open a stream, but is unable to due to the maximum stream wishes to open a stream, but is unable to due to the maximum stream
ID limit set by its peer (see Section 8.8). This does not open the ID limit set by its peer (see Section 7.8). This does not open the
stream, but informs the peer that a new stream was needed, but the stream, but informs the peer that a new stream was needed, but the
stream limit prevented the creation of the stream. stream limit prevented the creation of the stream.
The STREAM_ID_BLOCKED frame is as follows: The STREAM_ID_BLOCKED frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (i) ... | Stream ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The STREAM_ID_BLOCKED frame contains a single field. The STREAM_ID_BLOCKED frame contains a single field.
Stream ID: A variable-length integer indicating the highest stream Stream ID: A variable-length integer indicating the highest stream
ID that the sender was permitted to open. ID that the sender was permitted to open.
8.13. NEW_CONNECTION_ID Frame 7.13. NEW_CONNECTION_ID Frame
A server sends a NEW_CONNECTION_ID frame (type=0x0b) to provide the An endpoint sends a NEW_CONNECTION_ID frame (type=0x0b) to provide
client with alternative connection IDs that can be used to break its peer with alternative connection IDs that can be used to break
linkability when migrating connections (see Section 7.7.1). linkability when migrating connections (see Section 6.8.5).
The NEW_CONNECTION_ID is as follows: The NEW_CONNECTION_ID is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence (i) ... | Sequence (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | Length (8) | Connection ID (32..144) ...
+ Connection ID (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ Stateless Reset Token (128) + + Stateless Reset Token (128) +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are: The fields are:
Sequence: A variable-length integer. This value starts at 0 and Sequence: A variable-length integer. This value starts at 0 and
increases by 1 for each connection ID that is provided by the increases by 1 for each connection ID that is provided by the
server. The connection ID that is assigned during the handshake server. The connection ID that is assigned during the handshake
is assumed to have a sequence of -1. That is, the value selected is assumed to have a sequence of -1. That is, the value selected
during the handshake comes immediately before the first value that during the handshake comes immediately before the first value that
a server can send. a server can send.
Connection ID: A 64-bit connection ID. Length: An 8-bit unsigned integer containing the length of the
connection ID. Values less than 4 and greater than 18 are invalid
and MUST be treated as a connection error of type
PROTOCOL_VIOLATION.
Connection ID: A connection ID of the specified length.
Stateless Reset Token: A 128-bit value that will be used to for a Stateless Reset Token: A 128-bit value that will be used to for a
stateless reset when the associated connection ID is used (see stateless reset when the associated connection ID is used (see
Section 7.9.4). Section 6.9.4).
8.14. STOP_SENDING Frame An endpoint MUST NOT send this frame if it currently requires that
its peer send packets with a zero-length Destination Connection ID.
Changing the length of a connection ID to or from zero-length makes
it difficult to identify when the value of the connection ID changed.
An endpoint that is sending packets with a zero-length Destination
Connection ID MUST treat receipt of a NEW_CONNECTION_ID frame as a
connection error of type PROTOCOL_VIOLATION.
7.14. STOP_SENDING Frame
An endpoint may use a STOP_SENDING frame (type=0x0c) to communicate An endpoint may use a STOP_SENDING frame (type=0x0c) to communicate
that incoming data is being discarded on receipt at application that incoming data is being discarded on receipt at application
request. This signals a peer to abruptly terminate transmission on a request. This signals a peer to abruptly terminate transmission on a
stream. stream.
An endpoint that receives a STOP_SENDING frame for a receive-only Receipt of a STOP_SENDING frame is only valid for a send stream that
stream MUST terminate the connection with error PROTOCOL_VIOLATION. exists and is not in the "Ready" state (see Section 9.2.1).
Receiving a STOP_SENDING frame for a send stream that is "Ready" or
non-existent MUST be treated as a connection error of type
PROTOCOL_VIOLATION. An endpoint that receives a STOP_SENDING frame
for a receive-only stream MUST terminate the connection with error
PROTOCOL_VIOLATION.
The STOP_SENDING frame is as follows: The STOP_SENDING frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (i) ... | Stream ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Application Error Code (16) | | Application Error Code (16) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are: The fields are:
Stream ID: A variable-length integer carrying the Stream ID of the Stream ID: A variable-length integer carrying the Stream ID of the
stream being ignored. stream being ignored.
Application Error Code: A 16-bit, application-specified reason the Application Error Code: A 16-bit, application-specified reason the
sender is ignoring the stream (see Section 12.4). sender is ignoring the stream (see Section 11.4).
8.15. ACK Frame 7.15. ACK Frame
Receivers send ACK frames (type=0x0d) to inform senders which packets Receivers send ACK frames (type=0x0d) to inform senders which packets
they have received and processed. A sent packet that has never been they have received and processed. A sent packet that has never been
acknowledged is missing. The ACK frame contains any number of ACK acknowledged is missing. The ACK frame contains any number of ACK
blocks. ACK blocks are ranges of acknowledged packets. blocks. ACK blocks are ranges of acknowledged packets.
Unlike TCP SACKs, QUIC acknowledgements are irrevocable. Once a Unlike TCP SACKs, QUIC acknowledgements are irrevocable. Once a
packet has been acknowledged, even if it does not appear in a future packet has been acknowledged, even if it does not appear in a future
ACK frame, it remains acknowledged. ACK frame, it remains acknowledged.
A client MUST NOT acknowledge Retry packets. Retry packets include A client MUST NOT acknowledge Retry packets. Retry packets include
the packet number from the Initial packet it responds to. Version the packet number from the Initial packet it responds to. Version
Negotiation packets cannot be acknowledged because they do not Negotiation packets cannot be acknowledged because they do not
contain a packet number. Rather than relying on ACK frames, these contain a packet number. Rather than relying on ACK frames, these
packets are implicitly acknowledged by the next Initial packet sent packets are implicitly acknowledged by the next Initial packet sent
by the client. by the client.
A sender MAY intentionally skip packet numbers to introduce entropy
into the connection, to avoid opportunistic acknowledgement attacks.
The sender SHOULD close the connection if an unsent packet number is
acknowledged. The format of the ACK frame is efficient at expressing
even long blocks of missing packets, allowing for large,
unpredictable gaps.
An ACK frame is shown below. An ACK frame is shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Largest Acknowledged (i) ... | Largest Acknowledged (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Delay (i) ... | ACK Delay (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Block Count (i) ... | ACK Block Count (i) ...
skipping to change at page 55, line 34 skipping to change at page 59, line 38
generating the ACK frame. Unlike the packet number in the QUIC generating the ACK frame. Unlike the packet number in the QUIC
long or short header, the value in an ACK frame is not truncated. long or short header, the value in an ACK frame is not truncated.
ACK Delay: A variable-length integer including the time in ACK Delay: A variable-length integer including the time in
microseconds that the largest acknowledged packet, as indicated in microseconds that the largest acknowledged packet, as indicated in
the Largest Acknowledged field, was received by this peer to when the Largest Acknowledged field, was received by this peer to when
this ACK was sent. The value of the ACK Delay field is scaled by this ACK was sent. The value of the ACK Delay field is scaled by
multiplying the encoded value by the 2 to the power of the value multiplying the encoded value by the 2 to the power of the value
of the "ack_delay_exponent" transport parameter set by the sender of the "ack_delay_exponent" transport parameter set by the sender
of the ACK frame. The "ack_delay_exponent" defaults to 3, or a of the ACK frame. The "ack_delay_exponent" defaults to 3, or a
multiplier of 8 (see Section 7.4.1). Scaling in this fashion multiplier of 8 (see Section 6.4.1). Scaling in this fashion
allows for a larger range of values with a shorter encoding at the allows for a larger range of values with a shorter encoding at the
cost of lower resolution. cost of lower resolution.
ACK Block Count: The number of Additional ACK Block (and Gap) fields ACK Block Count: The number of Additional ACK Block (and Gap) fields
after the First ACK Block. after the First ACK Block.
ACK Blocks: Contains one or more blocks of packet numbers which have ACK Blocks: Contains one or more blocks of packet numbers which have
been successfully received, see Section 8.15.1. been successfully received, see Section 7.15.1.
8.15.1. ACK Block Section 7.15.1. ACK Block Section
The ACK Block Section consists of alternating Gap and ACK Block The ACK Block Section consists of alternating Gap and ACK Block
fields in descending packet number order. A First Ack Block field is fields in descending packet number order. A First Ack Block field is
followed by a variable number of alternating Gap and Additional ACK followed by a variable number of alternating Gap and Additional ACK
Blocks. The number of Gap and Additional ACK Block fields is Blocks. The number of Gap and Additional ACK Block fields is
determined by the ACK Block Count field. determined by the ACK Block Count field.
Gap and ACK Block fields use a relative integer encoding for Gap and ACK Block fields use a relative integer encoding for
efficiency. Though each encoded value is positive, the values are efficiency. Though each encoded value is positive, the values are
subtracted, so that each ACK Block describes progressively lower- subtracted, so that each ACK Block describes progressively lower-
skipping to change at page 57, line 34 skipping to change at page 61, line 42
being acknowledged. being acknowledged.
Gap (repeated): A variable-length integer indicating the number of Gap (repeated): A variable-length integer indicating the number of
contiguous unacknowledged packets preceding the packet number one contiguous unacknowledged packets preceding the packet number one
lower than the smallest in the preceding ACK Block. lower than the smallest in the preceding ACK Block.
ACK Block (repeated): A variable-length integer indicating the ACK Block (repeated): A variable-length integer indicating the
number of contiguous acknowledged packets preceding the largest number of contiguous acknowledged packets preceding the largest
packet number, as determined by the preceding Gap. packet number, as determined by the preceding Gap.
8.15.2. Sending ACK Frames 7.15.2. Sending ACK Frames
Implementations MUST NOT generate packets that only contain ACK Implementations MUST NOT generate packets that only contain ACK
frames in response to packets which only contain ACK frames. frames in response to packets which only contain ACK frames.
However, they MUST acknowledge packets containing only ACK frames However, they MUST acknowledge packets containing only ACK frames
when sending ACK frames in response to other packets. when sending ACK frames in response to other packets.
Implementations MUST NOT send more than one ACK frame per received Implementations MUST NOT send more than one packet containing only
packet that contains frames other than ACK frames. Packets ACK frames per received packet that contains frames other than ACK
containing non-ACK frames MUST be acknowledged immediately or when a frames. Packets containing non-ACK frames MUST be acknowledged
delayed ack timer expires. immediately or when a delayed ack timer expires.
To limit ACK blocks to those that have not yet been received by the To limit ACK blocks to those that have not yet been received by the
sender, the receiver SHOULD track which ACK frames have been sender, the receiver SHOULD track which ACK frames have been
acknowledged by its peer. Once an ACK frame has been acknowledged, acknowledged by its peer. Once an ACK frame has been acknowledged,
the packets it acknowledges SHOULD NOT be acknowledged again. the packets it acknowledges SHOULD NOT be acknowledged again.
A receiver that is only sending ACK frames will not receive Because ACK frames are not sent in response to ACK-only packets, a
acknowledgments for its packets. Sending an occasional MAX_DATA or receiver that is only sending ACK frames will only receive
MAX_STREAM_DATA frame as data is received will ensure that acknowledgements for its packets if the sender includes them in
acknowledgements are generated by a peer. Otherwise, an endpoint MAY packets with non-ACK frames. A sender SHOULD bundle ACK frames with
send a PING frame once per RTT to solicit an acknowledgment. other frames when possible.
To limit receiver state or the size of ACK frames, a receiver MAY To limit receiver state or the size of ACK frames, a receiver MAY
limit the number of ACK blocks it sends. A receiver can do this even limit the number of ACK blocks it sends. A receiver can do this even
without receiving acknowledgment of its ACK frames, with the without receiving acknowledgment of its ACK frames, with the
knowledge this could cause the sender to unnecessarily retransmit knowledge this could cause the sender to unnecessarily retransmit
some data. Standard QUIC [QUIC-RECOVERY] algorithms declare packets some data. Standard QUIC [QUIC-RECOVERY] algorithms declare packets
lost after sufficiently newer packets are acknowledged. Therefore, lost after sufficiently newer packets are acknowledged. Therefore,
the receiver SHOULD repeatedly acknowledge newly received packets in the receiver SHOULD repeatedly acknowledge newly received packets in
preference to packets received in the past. preference to packets received in the past.
8.15.3. ACK Frames and Packet Protection 7.15.3. ACK Frames and Packet Protection
ACK frames that acknowledge protected packets MUST be carried in a ACK frames that acknowledge protected packets MUST be carried in a
packet that has an equivalent or greater level of packet protection. packet that has an equivalent or greater level of packet protection.
Packets that are protected with 1-RTT keys MUST be acknowledged in Packets that are protected with 1-RTT keys MUST be acknowledged in
packets that are also protected with 1-RTT keys. packets that are also protected with 1-RTT keys.
A packet that is not protected and claims to acknowledge a packet A packet that is not protected and claims to acknowledge a packet
number that was sent with packet protection is not valid. An number that was sent with packet protection is not valid. An
unprotected packet that carries acknowledgments for protected packets unprotected packet that carries acknowledgments for protected packets
skipping to change at page 59, line 13 skipping to change at page 63, line 21
protection keys. protection keys.
For instance, a server acknowledges a TLS ClientHello in the packet For instance, a server acknowledges a TLS ClientHello in the packet
that carries the TLS ServerHello; similarly, a client can acknowledge that carries the TLS ServerHello; similarly, a client can acknowledge
a TLS HelloRetryRequest in the packet containing a second TLS a TLS HelloRetryRequest in the packet containing a second TLS
ClientHello. The complete set of server handshake messages (TLS ClientHello. The complete set of server handshake messages (TLS
ServerHello through to Finished) might be acknowledged by a client in ServerHello through to Finished) might be acknowledged by a client in
protected packets, because it is certain that the server is able to protected packets, because it is certain that the server is able to
decipher the packet. decipher the packet.
8.16. PATH_CHALLENGE Frame 7.16. PATH_CHALLENGE Frame
Endpoints can use PATH_CHALLENGE frames (type=0x0e) to check Endpoints can use PATH_CHALLENGE frames (type=0x0e) to check
reachability to the peer and for address validation during connection reachability to the peer and for path validation during connection
establishment and connection migration. establishment and connection migration.
PATH_CHALLENGE frames contain an 8-byte payload. PATH_CHALLENGE frames contain an 8-byte payload.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Data (8) + + Data (8) +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data: This 8-byte field contains arbitrary data. Data: This 8-byte field contains arbitrary data.
A PATH_CHALLENGE frame containing 8 octets that are hard to guess is A PATH_CHALLENGE frame containing 8 octets that are hard to guess is
sufficient to ensure that it is easier to receive the packet than it sufficient to ensure that it is easier to receive the packet than it
is to guess the value correctly. is to guess the value correctly.
The recipient of this frame MUST generate a PATH_RESPONSE frame The recipient of this frame MUST generate a PATH_RESPONSE frame
(Section 8.17) containing the same Data. (Section 7.17) containing the same Data.
8.17. PATH_RESPONSE Frame 7.17. PATH_RESPONSE Frame
The PATH_RESPONSE frame (type=0x0f) is sent in response to a The PATH_RESPONSE frame (type=0x0f) is sent in response to a
PATH_CHALLENGE frame. Its format is identical to the PATH_CHALLENGE PATH_CHALLENGE frame. Its format is identical to the PATH_CHALLENGE
frame (Section 8.16). frame (Section 7.16).
If the content of a PATH_RESPONSE frame does not match the content of If the content of a PATH_RESPONSE frame does not match the content of
a PATH_CHALLENGE frame previously sent by the endpoint, the endpoint a PATH_CHALLENGE frame previously sent by the endpoint, the endpoint
MAY generate a connection error of type UNSOLICITED_PATH_RESPONSE. MAY generate a connection error of type UNSOLICITED_PATH_RESPONSE.
8.18. STREAM Frames 7.18. STREAM Frames
STREAM frames implicitly create a stream and carry stream data. The STREAM frames implicitly create a stream and carry stream data. The
STREAM frame takes the form 0b00010XXX (or the set of values from STREAM frame takes the form 0b00010XXX (or the set of values from
0x10 to 0x17). The value of the three low-order bits of the frame 0x10 to 0x17). The value of the three low-order bits of the frame
type determine the fields that are present in the frame. type determine the fields that are present in the frame.
o The OFF bit (0x04) in the frame type is set to indicate that there o The OFF bit (0x04) in the frame type is set to indicate that there
is an Offset field present. When set to 1, the Offset field is is an Offset field present. When set to 1, the Offset field is
present; when set to 0, the Offset field is absent and the Stream present; when set to 0, the Offset field is absent and the Stream
Data starts at an offset of 0 (that is, the frame contains the Data starts at an offset of 0 (that is, the frame contains the
skipping to change at page 60, line 50 skipping to change at page 65, line 6
| [Length (i)] ... | [Length (i)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream Data (*) ... | Stream Data (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: STREAM Frame Format Figure 9: STREAM Frame Format
The STREAM frame contains the following fields: The STREAM frame contains the following fields:
Stream ID: A variable-length integer indicating the stream ID of the Stream ID: A variable-length integer indicating the stream ID of the
stream (see Section 10.1). stream (see Section 9.1).
Offset: A variable-length integer specifying the byte offset in the Offset: A variable-length integer specifying the byte offset in the
stream for the data in this STREAM frame. This field is present stream for the data in this STREAM frame. This field is present
when the OFF bit is set to 1. When the Offset field is absent, when the OFF bit is set to 1. When the Offset field is absent,
the offset is 0. the offset is 0.
Length: A variable-length integer specifying the length of the Length: A variable-length integer specifying the length of the
Stream Data field in this STREAM frame. This field is present Stream Data field in this STREAM frame. This field is present
when the LEN bit is set to 1. When the LEN bit is set to 0, the when the LEN bit is set to 1. When the LEN bit is set to 0, the
Stream Data field consumes all the remaining octets in the packet. Stream Data field consumes all the remaining octets in the packet.
Stream Data: The bytes from the designated stream to be delivered. Stream Data: The bytes from the designated stream to be delivered.
A stream frame's Stream Data MUST NOT be empty, unless the FIN bit is A stream frame's Stream Data MUST NOT be empty, unless the offset is
set. When the FIN flag is sent on an empty STREAM frame, the offset 0 or the FIN bit is set. When the FIN flag is sent on an empty
in the STREAM frame is the offset of the next byte that would be STREAM frame, the offset in the STREAM frame is the offset of the
sent. next byte that would be sent.
The first byte in the stream has an offset of 0. The largest offset The first byte in the stream has an offset of 0. The largest offset
delivered on a stream - the sum of the re-constructed offset and data delivered on a stream - the sum of the re-constructed offset and data
length - MUST be less than 2^62. length - MUST be less than 2^62.
Stream multiplexing is achieved by interleaving STREAM frames from Stream multiplexing is achieved by interleaving STREAM frames from
multiple streams into one or more QUIC packets. A single QUIC packet multiple streams into one or more QUIC packets. A single QUIC packet
can include multiple STREAM frames from one or more streams. can include multiple STREAM frames from one or more streams.
Implementation note: One of the benefits of QUIC is avoidance of Implementation note: One of the benefits of QUIC is avoidance of
head-of-line blocking across multiple streams. When a packet loss head-of-line blocking across multiple streams. When a packet loss
occurs, only streams with data in that packet are blocked waiting for occurs, only streams with data in that packet are blocked waiting for
a retransmission to be received, while other streams can continue a retransmission to be received, while other streams can continue
making progress. Note that when data from multiple streams is making progress. Note that when data from multiple streams is
bundled into a single QUIC packet, loss of that packet blocks all bundled into a single QUIC packet, loss of that packet blocks all
those streams from making progress. An implementation is therefore those streams from making progress. An implementation is therefore
advised to bundle as few streams as necessary in outgoing packets advised to bundle as few streams as necessary in outgoing packets
without losing transmission efficiency to underfilled packets. without losing transmission efficiency to underfilled packets.
9. Packetization and Reliability 8. Packetization and Reliability
A sender bundles one or more frames in a QUIC packet (see Section 6). A sender bundles one or more frames in a QUIC packet (see Section 5).
A sender SHOULD minimize per-packet bandwidth and computational costs A sender SHOULD minimize per-packet bandwidth and computational costs
by bundling as many frames as possible within a QUIC packet. A by bundling as many frames as possible within a QUIC packet. A
sender MAY wait for a short period of time to bundle multiple frames sender MAY wait for a short period of time to bundle multiple frames
before sending a packet that is not maximally packed, to avoid before sending a packet that is not maximally packed, to avoid
sending out large numbers of small packets. An implementation may sending out large numbers of small packets. An implementation may
use knowledge about application sending behavior or heuristics to use knowledge about application sending behavior or heuristics to
determine whether and for how long to wait. This waiting period is determine whether and for how long to wait. This waiting period is
an implementation decision, and an implementation should be careful an implementation decision, and an implementation should be careful
to delay conservatively, since any delay is likely to increase to delay conservatively, since any delay is likely to increase
application-visible latency. application-visible latency.
9.1. Packet Processing and Acknowledgment 8.1. Packet Processing and Acknowledgment
A packet MUST NOT be acknowledged until packet protection has been A packet MUST NOT be acknowledged until packet protection has been
successfully removed and all frames contained in the packet have been successfully removed and all frames contained in the packet have been
processed. Any stream state transitions triggered by the frame MUST processed. Any stream state transitions triggered by the frame MUST
have occurred. For STREAM frames, this means the data has been have occurred. For STREAM frames, this means the data has been
enqueued in preparation to be received by the application protocol, enqueued in preparation to be received by the application protocol,
but it does not require that data is delivered and consumed. but it does not require that data is delivered and consumed.
Once the packet has been fully processed, a receiver acknowledges Once the packet has been fully processed, a receiver acknowledges
receipt by sending one or more ACK frames containing the packet receipt by sending one or more ACK frames containing the packet
number of the received packet. To avoid creating an indefinite number of the received packet. To avoid creating an indefinite
feedback loop, an endpoint MUST NOT send an ACK frame in response to feedback loop, an endpoint MUST NOT send an ACK frame in response to
a packet containing only ACK or PADDING frames, even if there are a packet containing only ACK or PADDING frames, even if there are
packet gaps which precede the received packet. The endpoint MUST packet gaps which precede the received packet. The endpoint MUST
acknowledge packets containing only ACK or PADDING frames in the next acknowledge packets containing only ACK or PADDING frames in the next
ACK frame that it sends. ACK frame that it sends.
Strategies and implications of the frequency of generating Strategies and implications of the frequency of generating
acknowledgments are discussed in more detail in [QUIC-RECOVERY]. acknowledgments are discussed in more detail in [QUIC-RECOVERY].
9.2. Retransmission of Information 8.2. Retransmission of Information
QUIC packets that are determined to be lost are not retransmitted QUIC packets that are determined to be lost are not retransmitted
whole. The same applies to the frames that are contained within lost whole. The same applies to the frames that are contained within lost
packets. Instead, the information that might be carried in frames is packets. Instead, the information that might be carried in frames is
sent again in new frames as needed. sent again in new frames as needed.
New frames and packets are used to carry information that is New frames and packets are used to carry information that is
determined to have been lost. In general, information is sent again determined to have been lost. In general, information is sent again
when a packet containing that information is determined to be lost when a packet containing that information is determined to be lost
and sending ceases when a packet containing that information is and sending ceases when a packet containing that information is
acknowledged. acknowledged.
o Application data sent in STREAM frames is retransmitted in new o Application data sent in STREAM frames is retransmitted in new
STREAM frames unless the endpoint has sent a RST_STREAM for that STREAM frames unless the endpoint has sent a RST_STREAM for that
stream. Once an endpoint sends a RST_STREAM frame, no further stream. Once an endpoint sends a RST_STREAM frame, no further
STREAM frames are needed. STREAM frames are needed.
o The most recent set of acknowledgments are sent in ACK frames. An o The most recent set of acknowledgments are sent in ACK frames. An
ACK frame SHOULD contain all unacknowledged acknowledgments, as ACK frame SHOULD contain all unacknowledged acknowledgments, as
described in Section 8.15.2. described in Section 7.15.2.
o Cancellation of stream transmission, as carried in a RST_STREAM o Cancellation of stream transmission, as carried in a RST_STREAM
frame, is sent until acknowledged or until all stream data is frame, is sent until acknowledged or until all stream data is
acknowledged by the peer (that is, either the "Reset Recvd" or acknowledged by the peer (that is, either the "Reset Recvd" or
"Data Recvd" state is reached on the send stream). The content of "Data Recvd" state is reached on the send stream). The content of
a RST_STREAM frame MUST NOT change when it is sent again. a RST_STREAM frame MUST NOT change when it is sent again.
o Similarly, a request to cancel stream transmission, as encoded in o Similarly, a request to cancel stream transmission, as encoded in
a STOP_SENDING frame, is sent until the receive stream enters a STOP_SENDING frame, is sent until the receive stream enters
either a "Data Recvd" or "Reset Recvd" state, see Section 10.3. either a "Data Recvd" or "Reset Recvd" state, see Section 9.3.
o Connection close signals, including those that use o Connection close signals, including those that use
CONNECTION_CLOSE and APPLICATION_CLOSE frames, are not sent again CONNECTION_CLOSE and APPLICATION_CLOSE frames, are not sent again
when packet loss is detected, but as described in Section 7.9. when packet loss is detected, but as described in Section 6.9.
o The current connection maximum data is sent in MAX_DATA frames. o The current connection maximum data is sent in MAX_DATA frames.
An updated value is sent in a MAX_DATA frame if the packet An updated value is sent in a MAX_DATA frame if the packet
containing the most recently sent MAX_DATA frame is declared lost, containing the most recently sent MAX_DATA frame is declared lost,
or when the endpoint decides to update the limit. Care is or when the endpoint decides to update the limit. Care is
necessary to avoid sending this frame too often as the limit can necessary to avoid sending this frame too often as the limit can
increase frequently and cause an unnecessarily large number of increase frequently and cause an unnecessarily large number of
MAX_DATA frames to be sent. MAX_DATA frames to be sent.
o The current maximum stream data offset is sent in MAX_STREAM_DATA o The current maximum stream data offset is sent in MAX_STREAM_DATA
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o New connection IDs are sent in NEW_CONNECTION_ID frames and o New connection IDs are sent in NEW_CONNECTION_ID frames and
retransmitted if the packet containing them is lost. retransmitted if the packet containing them is lost.
o PADDING frames contain no information, so lost PADDING frames do o PADDING frames contain no information, so lost PADDING frames do
not require repair. not require repair.
Upon detecting losses, a sender MUST take appropriate congestion Upon detecting losses, a sender MUST take appropriate congestion
control action. The details of loss detection and congestion control control action. The details of loss detection and congestion control
are described in [QUIC-RECOVERY]. are described in [QUIC-RECOVERY].
9.3. Packet Size 8.3. Packet Size
The QUIC packet size includes the QUIC header and integrity check, The QUIC packet size includes the QUIC header and integrity check,
but not the UDP or IP header. but not the UDP or IP header.
Clients MUST pad any Initial packet it sends to have a QUIC packet Clients MUST pad any Initial packet it sends to have a QUIC packet
size of at least 1200 octets. Sending an Initial packet of this size size of at least 1200 octets. Sending an Initial packet of this size
ensures that the network path supports a reasonably sized packet, and ensures that the network path supports a reasonably sized packet, and
helps reduce the amplitude of amplification attacks caused by server helps reduce the amplitude of amplification attacks caused by server
responses toward an unverified client address. responses toward an unverified client address.
An Initial packet MAY exceed 1200 octets if the client knows that the An Initial packet MAY exceed 1200 octets if the client knows that the
Path Maximum Transmission Unit (PMTU) supports the size that it Path Maximum Transmission Unit (PMTU) supports the size that it
chooses. chooses.
A server MAY send a CONNECTION_CLOSE frame with error code A server MAY send a CONNECTION_CLOSE frame with error code
PROTOCOL_VIOLATION in response to an Initial packet smaller than 1200 PROTOCOL_VIOLATION in response to an Initial packet smaller than 1200
octets. It MUST NOT send any other frame type in response, or octets. It MUST NOT send any other frame type in response, or
otherwise behave as if any part of the offending packet was processed otherwise behave as if any part of the offending packet was processed
as valid. as valid.
9.4. Path Maximum Transmission Unit 8.4. Path Maximum Transmission Unit
The Path Maximum Transmission Unit (PMTU) is the maximum size of the The Path Maximum Transmission Unit (PMTU) is the maximum size of the
entire IP header, UDP header, and UDP payload. The UDP payload entire IP header, UDP header, and UDP payload. The UDP payload
includes the QUIC packet header, protected payload, and any includes the QUIC packet header, protected payload, and any
authentication fields. authentication fields.
All QUIC packets SHOULD be sized to fit within the estimated PMTU to All QUIC packets SHOULD be sized to fit within the estimated PMTU to
avoid IP fragmentation or packet drops. To optimize bandwidth avoid IP fragmentation or packet drops. To optimize bandwidth
efficiency, endpoints SHOULD use Packetization Layer PMTU Discovery efficiency, endpoints SHOULD use Packetization Layer PMTU Discovery
([PLPMTUD]). Endpoints MAY use PMTU Discovery ([PMTUDv4], [PMTUDv6]) ([PLPMTUD]). Endpoints MAY use PMTU Discovery ([PMTUDv4], [PMTUDv6])
skipping to change at page 65, line 29 skipping to change at page 69, line 32
most modern IPv4 networks. An endpoint MUST NOT reduce its MTU below most modern IPv4 networks. An endpoint MUST NOT reduce its MTU below
this number, even if it receives signals that indicate a smaller this number, even if it receives signals that indicate a smaller
limit might exist. limit might exist.
If a QUIC endpoint determines that the PMTU between any pair of local If a QUIC endpoint determines that the PMTU between any pair of local
and remote IP addresses has fallen below 1280 octets, it MUST and remote IP addresses has fallen below 1280 octets, it MUST
immediately cease sending QUIC packets on the affected path. This immediately cease sending QUIC packets on the affected path. This
could result in termination of the connection if an alternative path could result in termination of the connection if an alternative path
cannot be found. cannot be found.
9.4.1. Special Considerations for PMTU Discovery 8.4.1. Special Considerations for PMTU Discovery
Traditional ICMP-based path MTU discovery in IPv4 [RFC1191] is Traditional ICMP-based path MTU discovery in IPv4 [RFC1191] is
potentially vulnerable to off-path attacks that successfully guess potentially vulnerable to off-path attacks that successfully guess
the IP/port 4-tuple and reduce the MTU to a bandwidth-inefficient the IP/port 4-tuple and reduce the MTU to a bandwidth-inefficient
value. TCP connections mitigate this risk by using the (at minimum) value. TCP connections mitigate this risk by using the (at minimum)
8 bytes of transport header echoed in the ICMP message to validate 8 bytes of transport header echoed in the ICMP message to validate
the TCP sequence number as valid for the current connection. the TCP sequence number as valid for the current connection.
However, as QUIC operates over UDP, in IPv4 the echoed information However, as QUIC operates over UDP, in IPv4 the echoed information
could consist only of the IP and UDP headers, which usually has could consist only of the IP and UDP headers, which usually has
insufficient entropy to mitigate off-path attacks. insufficient entropy to mitigate off-path attacks.
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spurious. spurious.
o Store additional information from the IP or UDP headers from DF o Store additional information from the IP or UDP headers from DF
packets (for example, the IP ID or UDP checksum) to further packets (for example, the IP ID or UDP checksum) to further
authenticate incoming Datagram Too Big messages. authenticate incoming Datagram Too Big messages.
o Any reduction in PMTU due to a report contained in an ICMP packet o Any reduction in PMTU due to a report contained in an ICMP packet
is provisional until QUIC's loss detection algorithm determines is provisional until QUIC's loss detection algorithm determines
that the packet is actually lost. that the packet is actually lost.
9.4.2. Special Considerations for Packetization Layer PMTU Discovery 8.4.2. Special Considerations for Packetization Layer PMTU Discovery
The PADDING frame provides a useful option for PMTU probe packets The PADDING frame provides a useful option for PMTU probe packets
that does not exist in other transports. PADDING frames generate that does not exist in other transports. PADDING frames generate
acknowledgements, but their content need not be delivered reliably. acknowledgements, but their content need not be delivered reliably.
PADDING frames may delay the delivery of application data, as they PADDING frames may delay the delivery of application data, as they
consume the congestion window. However, by definition their likely consume the congestion window. However, by definition their likely
loss in a probe packet does not require delay-inducing retransmission loss in a probe packet does not require delay-inducing retransmission
of application data. of application data.
When implementing the algorithm in Section 7.2 of [RFC4821], the When implementing the algorithm in Section 7.2 of [RFC4821], the
initial value of search_low SHOULD be consistent with the IPv6 initial value of search_low SHOULD be consistent with the IPv6
minimum packet size. Paths that do not support this size cannot minimum packet size. Paths that do not support this size cannot
deliver Initial packets, and therefore are not QUIC-compliant. deliver Initial packets, and therefore are not QUIC-compliant.
Section 7.3 of [RFC4821] discusses tradeoffs between small and large Section 7.3 of [RFC4821] discusses tradeoffs between small and large
increases in the size of probe packets. As QUIC probe packets need increases in the size of probe packets. As QUIC probe packets need
not contain application data, aggressive increases in probe size not contain application data, aggressive increases in probe size
carry fewer consequences. carry fewer consequences.
10. Streams: QUIC's Data Structuring Abstraction 9. Streams: QUIC's Data Structuring Abstraction
Streams in QUIC provide a lightweight, ordered byte-stream Streams in QUIC provide a lightweight, ordered byte-stream
abstraction. abstraction.
There are two basic types of stream in QUIC. Unidirectional streams There are two basic types of stream in QUIC. Unidirectional streams
carry data in one direction only; bidirectional streams allow for carry data in one direction only; bidirectional streams allow for
data to be sent in both directions. Different stream identifiers are data to be sent in both directions. Different stream identifiers are
used to distinguish between unidirectional and bidirectional streams, used to distinguish between unidirectional and bidirectional streams,
as well as to create a separation between streams that are initiated as well as to create a separation between streams that are initiated
by the client and server (see Section 10.1). by the client and server (see Section 9.1).
Either type of stream can be created by either endpoint, can Either type of stream can be created by either endpoint, can
concurrently send data interleaved with other streams, and can be concurrently send data interleaved with other streams, and can be
cancelled. cancelled.
Stream offsets allow for the octets on a stream to be placed in Stream offsets allow for the octets on a stream to be placed in
order. An endpoint MUST be capable of delivering data received on a order. An endpoint MUST be capable of delivering data received on a
stream in order. Implementations MAY choose to offer the ability to stream in order. Implementations MAY choose to offer the ability to
deliver data out of order. There is no means of ensuring ordering deliver data out of order. There is no means of ensuring ordering
between octets on different streams. between octets on different streams.
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Streams are individually flow controlled, allowing an endpoint to Streams are individually flow controlled, allowing an endpoint to
limit memory commitment and to apply back pressure. The creation of limit memory commitment and to apply back pressure. The creation of
streams is also flow controlled, with each peer declaring the maximum streams is also flow controlled, with each peer declaring the maximum
stream ID it is willing to accept at a given time. stream ID it is willing to accept at a given time.
An alternative view of QUIC streams is as an elastic "message" An alternative view of QUIC streams is as an elastic "message"
abstraction, similar to the way ephemeral streams are used in SST abstraction, similar to the way ephemeral streams are used in SST
[SST], which may be a more appealing description for some [SST], which may be a more appealing description for some
applications. applications.
10.1. Stream Identifiers 9.1. Stream Identifiers
Streams are identified by an unsigned 62-bit integer, referred to as Streams are identified by an unsigned 62-bit integer, referred to as
the Stream ID. The least significant two bits of the Stream ID are the Stream ID. The least significant two bits of the Stream ID are
used to identify the type of stream (unidirectional or bidirectional) used to identify the type of stream (unidirectional or bidirectional)
and the initiator of the stream. and the initiator of the stream.
The least significant bit (0x1) of the Stream ID identifies the The least significant bit (0x1) of the Stream ID identifies the
initiator of the stream. Clients initiate even-numbered streams initiator of the stream. Clients initiate even-numbered streams
(those with the least significant bit set to 0); servers initiate (those with the least significant bit set to 0); servers initiate
odd-numbered streams (with the bit set to 1). Separation of the odd-numbered streams (with the bit set to 1). Separation of the
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| | | | | |
| 0x3 | Server-Initiated, Unidirectional | | 0x3 | Server-Initiated, Unidirectional |
+----------+----------------------------------+ +----------+----------------------------------+
Table 5: Stream ID Types Table 5: Stream ID Types
Stream ID 0 (0x0) is a client-initiated, bidirectional stream that is Stream ID 0 (0x0) is a client-initiated, bidirectional stream that is
used for the cryptographic handshake. Stream 0 MUST NOT be used for used for the cryptographic handshake. Stream 0 MUST NOT be used for
application data. application data.
A QUIC endpoint MUST NOT reuse a Stream ID. Open streams can be used A QUIC endpoint MUST NOT reuse a Stream ID. Streams can be used in
in any order. Streams that are used out of order result in opening any order. Streams that are used out of order result in opening all
all lower-numbered streams of the same type in the same direction. lower-numbered streams of the same type in the same direction.
Stream IDs are encoded as a variable-length integer (see Stream IDs are encoded as a variable-length integer (see
Section 8.1). Section 7.1).
10.2. Stream States 9.2. Stream States
This section describes the two types of QUIC stream in terms of the This section describes the two types of QUIC stream in terms of the
states of their send or receive components. Two state machines are states of their send or receive components. Two state machines are
described: one for streams on which an endpoint transmits data described: one for streams on which an endpoint transmits data
(Section 10.2.1); another for streams from which an endpoint receives (Section 9.2.1); another for streams from which an endpoint receives
data (Section 10.2.2). data (Section 9.2.2).
Unidirectional streams use the applicable state machine directly. Unidirectional streams use the applicable state machine directly.
Bidirectional streams use both state machines. For the most part, Bidirectional streams use both state machines. For the most part,
the use of these state machines is the same whether the stream is the use of these state machines is the same whether the stream is
unidirectional or bidirectional. The conditions for opening a stream unidirectional or bidirectional. The conditions for opening a stream
are slightly more complex for a bidirectional stream because the are slightly more complex for a bidirectional stream because the
opening of either send or receive causes the stream to open in both opening of either send or receive sides causes the stream to open in
directions. both directions.
Opening a stream causes all lower-numbered streams of the same type An endpoint can open streams up to its maximum stream limit in any
to implicitly open. This includes both send and receive streams if order, however endpoints SHOULD open the send side of streams for
the stream is bidirectional. For bidirectional streams, an endpoint each type in order.
can send data on an implicitly opened stream. On both unidirectional
and bidirectional streams, an endpoint MAY send MAX_STREAM_DATA or
STOP_SENDING on implicitly opened streams. An endpoint SHOULD NOT
implicitly open streams that it initiates, instead opening streams in
order.
Note: These states are largely informative. This document uses Note: These states are largely informative. This document uses
stream states to describe rules for when and how different types stream states to describe rules for when and how different types
of frames can be sent and the reactions that are expected when of frames can be sent and the reactions that are expected when
different types of frames are received. Though these state different types of frames are received. Though these state
machines are intended to be useful in implementing QUIC, these machines are intended to be useful in implementing QUIC, these
states aren't intended to constrain implementations. An states aren't intended to constrain implementations. An
implementation can define a different state machine as long as its implementation can define a different state machine as long as its
behavior is consistent with an implementation that implements behavior is consistent with an implementation that implements
these states. these states.
10.2.1. Send Stream States 9.2.1. Send Stream States
Figure 10 shows the states for the part of a stream that sends data Figure 10 shows the states for the part of a stream that sends data
to a peer. to a peer.
o o
| Open Stream (Sending) | Create Stream (Sending)
| Open Bidirectional Stream (Receiving) | Create Bidirectional Stream (Receiving)
v v
+-------+ +-------+
| Open | Send RST_STREAM | Ready | Send RST_STREAM
| |-----------------------. | |-----------------------.
+-------+ | +-------+ |
| | | |
| Send STREAM / | | Send STREAM / |
| STREAM_BLOCKED | | STREAM_BLOCKED |
v | v |
+-------+ | +-------+ |
| Send | Send RST_STREAM | | Send | Send RST_STREAM |
| |---------------------->| | |---------------------->|
+-------+ | +-------+ |
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v v v v
+-------+ +-------+ +-------+ +-------+
| Data | | Reset | | Data | | Reset |
| Recvd | | Recvd | | Recvd | | Recvd |
+-------+ +-------+ +-------+ +-------+
Figure 10: States for Send Streams Figure 10: States for Send Streams
The sending part of stream that the endpoint initiates (types 0 and 2 The sending part of stream that the endpoint initiates (types 0 and 2
for clients, 1 and 3 for servers) is opened by the application or for clients, 1 and 3 for servers) is opened by the application or
application protocol. The "Open" state represents a newly created application protocol. The "Ready" state represents a newly created
stream that is able to accept data from the application. Stream data stream that is able to accept data from the application. Stream data
might be buffered in this state in preparation for sending. might be buffered in this state in preparation for sending.
The sending part of a bidirectional stream initiated by a peer (type The sending part of a bidirectional stream initiated by a peer (type
0 for a server, type 1 for a client) enters the "Open" state if the 0 for a server, type 1 for a client) enters the "Ready" state if the
receiving part enters the "Recv" state. receiving part enters the "Recv" state.
Sending the first STREAM or STREAM_BLOCKED frame causes a send stream Sending the first STREAM or STREAM_BLOCKED frame causes a send stream
to enter the "Send" state. An implementation might choose to defer to enter the "Send" state. An implementation might choose to defer
allocating a Stream ID to a send stream until it sends the first allocating a Stream ID to a send stream until it sends the first
frame and enters this state, which can allow for better stream frame and enters this state, which can allow for better stream
prioritization. prioritization.
In the "Send" state, an endpoint transmits - and retransmits as In the "Send" state, an endpoint transmits - and retransmits as
necessary - data in STREAM frames. The endpoint respects the flow necessary - data in STREAM frames. The endpoint respects the flow
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retransmits stream data as necessary. The endpoint no longer needs retransmits stream data as necessary. The endpoint no longer needs
to track flow control limits or send STREAM_BLOCKED frames for a send to track flow control limits or send STREAM_BLOCKED frames for a send
stream in this state. The endpoint can ignore any MAX_STREAM_DATA stream in this state. The endpoint can ignore any MAX_STREAM_DATA
frames it receives from its peer in this state; MAX_STREAM_DATA frames it receives from its peer in this state; MAX_STREAM_DATA
frames might be received until the peer receives the final stream frames might be received until the peer receives the final stream
offset. offset.
Once all stream data has been successfully acknowledged, the send Once all stream data has been successfully acknowledged, the send
stream enters the "Data Recvd" state, which is a terminal state. stream enters the "Data Recvd" state, which is a terminal state.
From any of the "Open", "Send", or "Data Sent" states, an application From any of the "Ready", "Send", or "Data Sent" states, an
can signal that it wishes to abandon transmission of stream data. application can signal that it wishes to abandon transmission of
Similarly, the endpoint might receive a STOP_SENDING frame from its stream data. Similarly, the endpoint might receive a STOP_SENDING
peer. In either case, the endpoint sends a RST_STREAM frame, which frame from its peer. In either case, the endpoint sends a RST_STREAM
causes the stream to enter the "Reset Sent" state. frame, which causes the stream to enter the "Reset Sent" state.
An endpoint MAY send a RST_STREAM as the first frame on a send An endpoint MAY send a RST_STREAM as the first frame on a send
stream; this causes the send stream to open and then immediately stream; this causes the send stream to open and then immediately
transition to the "Reset Sent" state. transition to the "Reset Sent" state.
Once a packet containing a RST_STREAM has been acknowledged, the send Once a packet containing a RST_STREAM has been acknowledged, the send
stream enters the "Reset Recvd" state, which is a terminal state. stream enters the "Reset Recvd" state, which is a terminal state.
10.2.2. Receive Stream States 9.2.2. Receive Stream States
Figure 11 shows the states for the part of a stream that receives Figure 11 shows the states for the part of a stream that receives
data from a peer. The states for a receive stream mirror only some data from a peer. The states for a receive stream mirror only some
of the states of the send stream at the peer. A receive stream of the states of the send stream at the peer. A receive stream
doesn't track states on the send stream that cannot be observed, such doesn't track states on the send stream that cannot be observed, such
as the "Open" state; instead, receive streams track the delivery of as the "Ready" state; instead, receive streams track the delivery of
data to the application or application protocol some of which cannot data to the application or application protocol some of which cannot
be observed by the sender. be observed by the sender.
o o
| Recv STREAM / STREAM_BLOCKED / RST_STREAM | Recv STREAM / STREAM_BLOCKED / RST_STREAM
| Open Bidirectional Stream (Sending) | Create Bidirectional Stream (Sending)
| Recv MAX_STREAM_DATA | Recv MAX_STREAM_DATA
v v
+-------+ +-------+
| Recv | Recv RST_STREAM | Recv | Recv RST_STREAM
| |-----------------------. | |-----------------------.
+-------+ | +-------+ |
| | | |
| Recv STREAM + FIN | | Recv STREAM + FIN |
v | v |
+-------+ | +-------+ |
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The receiving part of a stream initiated by a peer (types 1 and 3 for The receiving part of a stream initiated by a peer (types 1 and 3 for
a client, or 0 and 2 for a server) are created when the first STREAM, a client, or 0 and 2 for a server) are created when the first STREAM,
STREAM_BLOCKED, RST_STREAM, or MAX_STREAM_DATA (bidirectional only, STREAM_BLOCKED, RST_STREAM, or MAX_STREAM_DATA (bidirectional only,
see below) is received for that stream. The initial state for a see below) is received for that stream. The initial state for a
receive stream is "Recv". Receiving a RST_STREAM frame causes the receive stream is "Recv". Receiving a RST_STREAM frame causes the
receive stream to immediately transition to the "Reset Recvd". receive stream to immediately transition to the "Reset Recvd".
The receive stream enters the "Recv" state when the sending part of a The receive stream enters the "Recv" state when the sending part of a
bidirectional stream initiated by the endpoint (type 0 for a client, bidirectional stream initiated by the endpoint (type 0 for a client,
type 1 for a server) enters the "Open" state. type 1 for a server) enters the "Ready" state.
A bidirectional stream also opens when a MAX_STREAM_DATA frame is A bidirectional stream also opens when a MAX_STREAM_DATA frame is
received. Receiving a MAX_STREAM_DATA frame implies that the remote received. Receiving a MAX_STREAM_DATA frame implies that the remote
peer has opened the stream and is providing flow control credit. A peer has opened the stream and is providing flow control credit. A
MAX_STREAM_DATA frame might arrive before a STREAM or STREAM_BLOCKED MAX_STREAM_DATA frame might arrive before a STREAM or STREAM_BLOCKED
frame if packets are lost or reordered. frame if packets are lost or reordered.
In the "Recv" state, the endpoint receives STREAM and STREAM_BLOCKED In the "Recv" state, the endpoint receives STREAM and STREAM_BLOCKED
frames. Incoming data is buffered and can be reassembled into the frames. Incoming data is buffered and can be reassembled into the
correct order for delivery to the application. As data is consumed correct order for delivery to the application. As data is consumed
by the application and buffer space becomes available, the endpoint by the application and buffer space becomes available, the endpoint
sends MAX_STREAM_DATA frames to allow the peer to send more data. sends MAX_STREAM_DATA frames to allow the peer to send more data.
When a STREAM frame with a FIN bit is received, the final offset (see When a STREAM frame with a FIN bit is received, the final offset (see
Section 11.3) is known. The receive stream enters the "Size Known" Section 10.3) is known. The receive stream enters the "Size Known"
state. In this state, the endpoint no longer needs to send state. In this state, the endpoint no longer needs to send
MAX_STREAM_DATA frames, it only receives any retransmissions of MAX_STREAM_DATA frames, it only receives any retransmissions of
stream data. stream data.
Once all data for the stream has been received, the receive stream Once all data for the stream has been received, the receive stream
enters the "Data Recvd" state. This might happen as a result of enters the "Data Recvd" state. This might happen as a result of
receiving the same STREAM frame that causes the transition to "Size receiving the same STREAM frame that causes the transition to "Size
Known". In this state, the endpoint has all stream data. Any STREAM Known". In this state, the endpoint has all stream data. Any STREAM
or STREAM_BLOCKED frames it receives for the stream can be discarded. or STREAM_BLOCKED frames it receives for the stream can be discarded.
skipping to change at page 74, line 5 skipping to change at page 77, line 14
of stream data, discard any data that was not consumed, and signal of stream data, discard any data that was not consumed, and signal
the existence of the RST_STREAM immediately. Alternatively, the the existence of the RST_STREAM immediately. Alternatively, the
RST_STREAM signal might be suppressed or withheld if stream data is RST_STREAM signal might be suppressed or withheld if stream data is
completely received. In the latter case, the receive stream completely received. In the latter case, the receive stream
effectively transitions to "Data Recvd" from "Reset Recvd". effectively transitions to "Data Recvd" from "Reset Recvd".
Once the application has been delivered the signal indicating that Once the application has been delivered the signal indicating that
the receive stream was reset, the receive stream transitions to the the receive stream was reset, the receive stream transitions to the
"Reset Read" state, which is a terminal state. "Reset Read" state, which is a terminal state.
10.2.3. Permitted Frame Types 9.2.3. Permitted Frame Types
The sender of a stream sends just three frame types that affect the The sender of a stream sends just three frame types that affect the
state of a stream at either sender or receiver: STREAM state of a stream at either sender or receiver: STREAM
(Section 8.18), STREAM_BLOCKED (Section 8.11), and RST_STREAM (Section 7.18), STREAM_BLOCKED (Section 7.11), and RST_STREAM
(Section 8.3). (Section 7.3).
A sender MUST NOT send any of these frames from a terminal state A sender MUST NOT send any of these frames from a terminal state
("Data Recvd" or "Reset Recvd"). A sender MUST NOT send STREAM or ("Data Recvd" or "Reset Recvd"). A sender MUST NOT send STREAM or
STREAM_BLOCKED after sending a RST_STREAM; that is, in the "Reset STREAM_BLOCKED after sending a RST_STREAM; that is, in the "Reset
Sent" state in addition to the terminal states. A receiver could Sent" state in addition to the terminal states. A receiver could
receive any of these frames in any state, but only due to the receive any of these frames in any state, but only due to the
possibility of delayed delivery of packets carrying them. possibility of delayed delivery of packets carrying them.
The receiver of a stream sends MAX_STREAM_DATA (Section 8.7) and The receiver of a stream sends MAX_STREAM_DATA (Section 7.7) and
STOP_SENDING frames (Section 8.14). STOP_SENDING frames (Section 7.14).
The receiver only sends MAX_STREAM_DATA in the "Recv" state. A The receiver only sends MAX_STREAM_DATA in the "Recv" state. A
receiver can send STOP_SENDING in any state where it has not received receiver can send STOP_SENDING in any state where it has not received
a RST_STREAM frame; that is states other than "Reset Recvd" or "Reset a RST_STREAM frame; that is states other than "Reset Recvd" or "Reset
Read". However there is little value in sending a STOP_SENDING frame Read". However there is little value in sending a STOP_SENDING frame
after all stream data has been received in the "Data Recvd" state. A after all stream data has been received in the "Data Recvd" state. A
sender could receive these frames in any state as a result of delayed sender could receive these frames in any state as a result of delayed
delivery of packets. delivery of packets.
10.2.4. Bidirectional Stream States 9.2.4. Bidirectional Stream States
A bidirectional stream is composed of a send stream and a receive A bidirectional stream is composed of a send stream and a receive
stream. Implementations may represent states of the bidirectional stream. Implementations may represent states of the bidirectional
stream as composites of send and receive stream states. The simplest stream as composites of send and receive stream states. The simplest
model presents the stream as "open" when either send or receive model presents the stream as "open" when either send or receive
stream is in a non-terminal state and "closed" when both send and stream is in a non-terminal state and "closed" when both send and
receive streams are in a terminal state. receive streams are in a terminal state.
Table 6 shows a more complex mapping of bidirectional stream states Table 6 shows a more complex mapping of bidirectional stream states
that loosely correspond to the stream states in HTTP/2 [HTTP2]. This that loosely correspond to the stream states in HTTP/2 [HTTP2]. This
shows that multiple states on send or receive streams are mapped to shows that multiple states on send or receive streams are mapped to
the same composite state. Note that this is just one possibility for the same composite state. Note that this is just one possibility for
such a mapping; this mapping requires that data is acknowledged such a mapping; this mapping requires that data is acknowledged
before the transition to a "closed" or "half-closed" state. before the transition to a "closed" or "half-closed" state.
+-----------------------+---------------------+---------------------+ +-----------------------+---------------------+---------------------+
| Send Stream | Receive Stream | Composite State | | Send Stream | Receive Stream | Composite State |
+-----------------------+---------------------+---------------------+ +-----------------------+---------------------+---------------------+
| No Stream/Open | No Stream/Recv *1 | idle | | No Stream/Ready | No Stream/Recv *1 | idle |
| | | | | | | |
| Open/Send/Data Sent | Recv/Size Known | open | | Ready/Send/Data Sent | Recv/Size Known | open |
| | | | | | | |
| Open/Send/Data Sent | Data Recvd/Data | half-closed | | Ready/Send/Data Sent | Data Recvd/Data | half-closed |
| | Read | (remote) | | | Read | (remote) |
| | | | | | | |
| Open/Send/Data Sent | Reset Recvd/Reset | half-closed | | Ready/Send/Data Sent | Reset Recvd/Reset | half-closed |
| | Read | (remote) | | | Read | (remote) |
| | | | | | | |
| Data Recvd | Recv/Size Known | half-closed (local) | | Data Recvd | Recv/Size Known | half-closed (local) |
| | | | | | | |
| Reset Sent/Reset | Recv/Size Known | half-closed (local) | | Reset Sent/Reset | Recv/Size Known | half-closed (local) |
| Recvd | | | | Recvd | | |
| | | | | | | |
| Data Recvd | Recv/Size Known | half-closed (local) | | Data Recvd | Recv/Size Known | half-closed (local) |
| | | | | | | |
| Reset Sent/Reset | Data Recvd/Data | closed | | Reset Sent/Reset | Data Recvd/Data | closed |
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| Data Recvd | Reset Recvd/Reset | closed | | Data Recvd | Reset Recvd/Reset | closed |
| | Read | | | | Read | |
+-----------------------+---------------------+---------------------+ +-----------------------+---------------------+---------------------+
Table 6: Possible Mapping of Stream States to HTTP/2 Table 6: Possible Mapping of Stream States to HTTP/2
Note (*1): A stream is considered "idle" if it has not yet been Note (*1): A stream is considered "idle" if it has not yet been
created, or if the receive stream is in the "Recv" state without created, or if the receive stream is in the "Recv" state without
yet having received any frames. yet having received any frames.
10.3. Solicited State Transitions 9.3. Solicited State Transitions
If an endpoint is no longer interested in the data it is receiving on If an endpoint is no longer interested in the data it is receiving on
a stream, it MAY send a STOP_SENDING frame identifying that stream to a stream, it MAY send a STOP_SENDING frame identifying that stream to
prompt closure of the stream in the opposite direction. This prompt closure of the stream in the opposite direction. This
typically indicates that the receiving application is no longer typically indicates that the receiving application is no longer
reading data it receives from the stream, but is not a guarantee that reading data it receives from the stream, but is not a guarantee that
incoming data will be ignored. incoming data will be ignored.
STREAM frames received after sending STOP_SENDING are still counted STREAM frames received after sending STOP_SENDING are still counted
toward the connection and stream flow-control windows, even though toward the connection and stream flow-control windows, even though
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STOP_SENDING SHOULD only be sent for a receive stream that has not STOP_SENDING SHOULD only be sent for a receive stream that has not
been reset. STOP_SENDING is most useful for streams in the "Recv" or been reset. STOP_SENDING is most useful for streams in the "Recv" or
"Size Known" states. "Size Known" states.
An endpoint is expected to send another STOP_SENDING frame if a An endpoint is expected to send another STOP_SENDING frame if a
packet containing a previous STOP_SENDING is lost. However, once packet containing a previous STOP_SENDING is lost. However, once
either all stream data or a RST_STREAM frame has been received for either all stream data or a RST_STREAM frame has been received for
the stream - that is, the stream is in any state other than "Recv" or the stream - that is, the stream is in any state other than "Recv" or
"Size Known" - sending a STOP_SENDING frame is unnecessary. "Size Known" - sending a STOP_SENDING frame is unnecessary.
10.4. Stream Concurrency 9.4. Stream Concurrency
An endpoint limits the number of concurrently active incoming streams An endpoint limits the number of concurrently active incoming streams
by adjusting the maximum stream ID. An initial value is set in the by adjusting the maximum stream ID. An initial value is set in the
transport parameters (see Section 7.4.1) and is subsequently transport parameters (see Section 6.4.1) and is subsequently
increased by MAX_STREAM_ID frames (see Section 8.8). increased by MAX_STREAM_ID frames (see Section 7.8).
The maximum stream ID is specific to each endpoint and applies only The maximum stream ID is specific to each endpoint and applies only
to the peer that receives the setting. That is, clients specify the to the peer that receives the setting. That is, clients specify the
maximum stream ID the server can initiate, and servers specify the maximum stream ID the server can initiate, and servers specify the
maximum stream ID the client can initiate. Each endpoint may respond maximum stream ID the client can initiate. Each endpoint may respond
on streams initiated by the other peer, regardless of whether it is on streams initiated by the other peer, regardless of whether it is
permitted to initiated new streams. permitted to initiated new streams.
Endpoints MUST NOT exceed the limit set by their peer. An endpoint Endpoints MUST NOT exceed the limit set by their peer. An endpoint
that receives a STREAM frame with an ID greater than the limit it has that receives a STREAM frame with an ID greater than the limit it has
sent MUST treat this as a stream error of type STREAM_ID_ERROR sent MUST treat this as a stream error of type STREAM_ID_ERROR
(Section 12), unless this is a result of a change in the initial (Section 11), unless this is a result of a change in the initial
offsets (see Section 7.4.2). offsets (see Section 6.4.2).
A receiver MUST NOT renege on an advertisement; that is, once a A receiver MUST NOT renege on an advertisement; that is, once a
receiver advertises a stream ID via a MAX_STREAM_ID frame, it MUST receiver advertises a stream ID via a MAX_STREAM_ID frame, it MUST
NOT subsequently advertise a smaller maximum ID. A sender may NOT subsequently advertise a smaller maximum ID. A sender may
receive MAX_STREAM_ID frames out of order; a sender MUST therefore receive MAX_STREAM_ID frames out of order; a sender MUST therefore
ignore any MAX_STREAM_ID that does not increase the maximum. ignore any MAX_STREAM_ID that does not increase the maximum.
10.5. Sending and Receiving Data 9.5. Sending and Receiving Data
Once a stream is created, endpoints may use the stream to send and Once a stream is created, endpoints may use the stream to send and
receive data. Each endpoint may send a series of STREAM frames receive data. Each endpoint may send a series of STREAM frames
encapsulating data on a stream until the stream is terminated in that encapsulating data on a stream until the stream is terminated in that
direction. Streams are an ordered byte-stream abstraction, and they direction. Streams are an ordered byte-stream abstraction, and they
have no other structure within them. STREAM frame boundaries are not have no other structure within them. STREAM frame boundaries are not
expected to be preserved in retransmissions from the sender or during expected to be preserved in retransmissions from the sender or during
delivery to the application at the receiver. delivery to the application at the receiver.
When new data is to be sent on a stream, a sender MUST set the When new data is to be sent on a stream, a sender MUST set the
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handshake stream, Stream 0, is exempt from the connection-level data handshake stream, Stream 0, is exempt from the connection-level data
limits established by MAX_DATA. Data on stream 0 other than the limits established by MAX_DATA. Data on stream 0 other than the
initial cryptographic handshake message is still subject to stream- initial cryptographic handshake message is still subject to stream-
level data limits and MAX_STREAM_DATA. This message is exempt from level data limits and MAX_STREAM_DATA. This message is exempt from
flow control because it needs to be sent in a single packet flow control because it needs to be sent in a single packet
regardless of the server's flow control state. This rule applies regardless of the server's flow control state. This rule applies
even for 0-RTT handshakes where the remembered value of even for 0-RTT handshakes where the remembered value of
MAX_STREAM_DATA would not permit sending a full initial cryptographic MAX_STREAM_DATA would not permit sending a full initial cryptographic
handshake message. handshake message.
Flow control is described in detail in Section 11, and congestion Flow control is described in detail in Section 10, and congestion
control is described in the companion document [QUIC-RECOVERY]. control is described in the companion document [QUIC-RECOVERY].
10.6. Stream Prioritization 9.6. Stream Prioritization
Stream multiplexing has a significant effect on application Stream multiplexing has a significant effect on application
performance if resources allocated to streams are correctly performance if resources allocated to streams are correctly
prioritized. Experience with other multiplexed protocols, such as prioritized. Experience with other multiplexed protocols, such as
HTTP/2 [HTTP2], shows that effective prioritization strategies have a HTTP/2 [HTTP2], shows that effective prioritization strategies have a
significant positive impact on performance. significant positive impact on performance.
QUIC does not provide frames for exchanging prioritization QUIC does not provide frames for exchanging prioritization
information. Instead it relies on receiving priority information information. Instead it relies on receiving priority information
from the application that uses QUIC. Protocols that use QUIC are from the application that uses QUIC. Protocols that use QUIC are
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Giving preference to the transmission of its own management frames Giving preference to the transmission of its own management frames
ensures that the protocol functions efficiently. That is, ensures that the protocol functions efficiently. That is,
prioritizing frames other than STREAM frames ensures that loss prioritizing frames other than STREAM frames ensures that loss
recovery, congestion control, and flow control operate effectively. recovery, congestion control, and flow control operate effectively.
Stream 0 MUST be prioritized over other streams prior to the Stream 0 MUST be prioritized over other streams prior to the
completion of the cryptographic handshake. This includes the completion of the cryptographic handshake. This includes the
retransmission of the second flight of client handshake messages, retransmission of the second flight of client handshake messages,
that is, the TLS Finished and any client authentication messages. that is, the TLS Finished and any client authentication messages.
STREAM frames that are determined to be lost SHOULD be retransmitted STREAM data in frames determined to be lost SHOULD be retransmitted
before sending new data, unless application priorities indicate before sending new data, unless application priorities indicate
otherwise. Retransmitting lost stream data can fill in gaps, which otherwise. Retransmitting lost stream data can fill in gaps, which
allows the peer to consume already received data and free up flow allows the peer to consume already received data and free up flow
control window. control window.
11. Flow Control 10. Flow Control
It is necessary to limit the amount of data that a sender may have It is necessary to limit the amount of data that a sender may have
outstanding at any time, so as to prevent a fast sender from outstanding at any time, so as to prevent a fast sender from
overwhelming a slow receiver, or to prevent a malicious sender from overwhelming a slow receiver, or to prevent a malicious sender from
consuming significant resources at a receiver. This section consuming significant resources at a receiver. This section
describes QUIC's flow-control mechanisms. describes QUIC's flow-control mechanisms.
QUIC employs a credit-based flow-control scheme similar to HTTP/2's QUIC employs a credit-based flow-control scheme similar to HTTP/2's
flow control [HTTP2]. A receiver advertises the number of octets it flow control [HTTP2]. A receiver advertises the number of octets it
is prepared to receive on a given stream and for the entire is prepared to receive on a given stream and for the entire
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A receiver MAY advertise a larger offset at any point by sending A receiver MAY advertise a larger offset at any point by sending
MAX_DATA or MAX_STREAM_DATA frames. A receiver MUST NOT renege on an MAX_DATA or MAX_STREAM_DATA frames. A receiver MUST NOT renege on an
advertisement; that is, once a receiver advertises an offset, it MUST advertisement; that is, once a receiver advertises an offset, it MUST
NOT subsequently advertise a smaller offset. A sender could receive NOT subsequently advertise a smaller offset. A sender could receive
MAX_DATA or MAX_STREAM_DATA frames out of order; a sender MUST MAX_DATA or MAX_STREAM_DATA frames out of order; a sender MUST
therefore ignore any flow control offset that does not move the therefore ignore any flow control offset that does not move the
window forward. window forward.
A receiver MUST close the connection with a FLOW_CONTROL_ERROR error A receiver MUST close the connection with a FLOW_CONTROL_ERROR error
(Section 12) if the peer violates the advertised connection or stream (Section 11) if the peer violates the advertised connection or stream
data limits. data limits.
A sender SHOULD send BLOCKED or STREAM_BLOCKED frames to indicate it A sender SHOULD send BLOCKED or STREAM_BLOCKED frames to indicate it
has data to write but is blocked by flow control limits. These has data to write but is blocked by flow control limits. These
frames are expected to be sent infrequently in common cases, but they frames are expected to be sent infrequently in common cases, but they
are considered useful for debugging and monitoring purposes. are considered useful for debugging and monitoring purposes.
A receiver advertises credit for a stream by sending a A receiver advertises credit for a stream by sending a
MAX_STREAM_DATA frame with the Stream ID set appropriately. A MAX_STREAM_DATA frame with the Stream ID set appropriately. A
receiver could use the current offset of data consumed to determine receiver could use the current offset of data consumed to determine
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Connection flow control is a limit to the total bytes of stream data Connection flow control is a limit to the total bytes of stream data
sent in STREAM frames on all streams except stream 0. A receiver sent in STREAM frames on all streams except stream 0. A receiver
advertises credit for a connection by sending a MAX_DATA frame. A advertises credit for a connection by sending a MAX_DATA frame. A
receiver maintains a cumulative sum of bytes received on all receiver maintains a cumulative sum of bytes received on all
contributing streams, which are used to check for flow control contributing streams, which are used to check for flow control
violations. A receiver might use a sum of bytes consumed on all violations. A receiver might use a sum of bytes consumed on all
contributing streams to determine the maximum data limit to be contributing streams to determine the maximum data limit to be
advertised. advertised.
11.1. Edge Cases and Other Considerations 10.1. Edge Cases and Other Considerations
There are some edge cases which must be considered when dealing with There are some edge cases which must be considered when dealing with
stream and connection level flow control. Given enough time, both stream and connection level flow control. Given enough time, both
endpoints must agree on flow control state. If one end believes it endpoints must agree on flow control state. If one end believes it
can send more than the other end is willing to receive, the can send more than the other end is willing to receive, the
connection will be torn down when too much data arrives. connection will be torn down when too much data arrives.
Conversely if a sender believes it is blocked, while endpoint B Conversely if a sender believes it is blocked, while endpoint B
expects more data can be received, then the connection can be in a expects more data can be received, then the connection can be in a
deadlock, with the sender waiting for a MAX_DATA or MAX_STREAM_DATA deadlock, with the sender waiting for a MAX_DATA or MAX_STREAM_DATA
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sent on the stream to make the same adjustment in its connection flow sent on the stream to make the same adjustment in its connection flow
controller. controller.
To avoid this de-synchronization, a RST_STREAM sender MUST include To avoid this de-synchronization, a RST_STREAM sender MUST include
the final byte offset sent on the stream in the RST_STREAM frame. On the final byte offset sent on the stream in the RST_STREAM frame. On
receiving a RST_STREAM frame, a receiver definitively knows how many receiving a RST_STREAM frame, a receiver definitively knows how many
bytes were sent on that stream before the RST_STREAM frame, and the bytes were sent on that stream before the RST_STREAM frame, and the
receiver MUST use the final offset to account for all bytes sent on receiver MUST use the final offset to account for all bytes sent on
the stream in its connection level flow controller. the stream in its connection level flow controller.
11.1.1. Response to a RST_STREAM 10.1.1. Response to a RST_STREAM
RST_STREAM terminates one direction of a stream abruptly. Whether RST_STREAM terminates one direction of a stream abruptly. Whether
any action or response can or should be taken on the data already any action or response can or should be taken on the data already
received is an application-specific issue, but it will often be the received is an application-specific issue, but it will often be the
case that upon receipt of a RST_STREAM an endpoint will choose to case that upon receipt of a RST_STREAM an endpoint will choose to
stop sending data in its own direction. If the sender of a stop sending data in its own direction. If the sender of a
RST_STREAM wishes to explicitly state that no future data will be RST_STREAM wishes to explicitly state that no future data will be
processed, that endpoint MAY send a STOP_SENDING frame at the same processed, that endpoint MAY send a STOP_SENDING frame at the same
time. time.
11.1.2. Data Limit Increments 10.1.2. Data Limit Increments
This document leaves when and how many bytes to advertise in a This document leaves when and how many bytes to advertise in a
MAX_DATA or MAX_STREAM_DATA to implementations, but offers a few MAX_DATA or MAX_STREAM_DATA to implementations, but offers a few
considerations. These frames contribute to connection overhead. considerations. These frames contribute to connection overhead.
Therefore frequently sending frames with small changes is Therefore frequently sending frames with small changes is
undesirable. At the same time, infrequent updates require larger undesirable. At the same time, infrequent updates require larger
increments to limits if blocking is to be avoided. Thus, larger increments to limits if blocking is to be avoided. Thus, larger
updates require a receiver to commit to larger resource commitments. updates require a receiver to commit to larger resource commitments.
Thus there is a tradeoff between resource commitment and overhead Thus there is a tradeoff between resource commitment and overhead
when determining how large a limit is advertised. when determining how large a limit is advertised.
A receiver MAY use an autotuning mechanism to tune the frequency and A receiver MAY use an autotuning mechanism to tune the frequency and
amount that it increases data limits based on a roundtrip time amount that it increases data limits based on a round-trip time
estimate and the rate at which the receiving application consumes estimate and the rate at which the receiving application consumes
data, similar to common TCP implementations. data, similar to common TCP implementations.
11.1.3. Handshake Exemption 10.1.3. Handshake Exemption
During the initial handshake, an endpoint could need to send a larger During the initial handshake, an endpoint could need to send a larger
message on stream 0 than would ordinarily be permitted by the peer's message on stream 0 than would ordinarily be permitted by the peer's
initial stream flow control window. Since MAX_STREAM_DATA frames are initial stream flow control window. Since MAX_STREAM_DATA frames are
not permitted in these early packets, the peer cannot provide not permitted in these early packets, the peer cannot provide
additional flow control window in order to complete the handshake. additional flow control window in order to complete the handshake.
Endpoints MAY exceed the flow control limits on stream 0 prior to the Endpoints MAY exceed the flow control limits on stream 0 prior to the
completion of the cryptographic handshake. (That is, in Initial, completion of the cryptographic handshake. (That is, in Initial,
Retry, and Handshake packets.) However, once the handshake is Retry, and Handshake packets.) However, once the handshake is
complete, endpoints MUST NOT send additional data beyond the peer's complete, endpoints MUST NOT send additional data beyond the peer's
permitted offset. If the amount of data sent during the handshake permitted offset. If the amount of data sent during the handshake
exceeds the peer's maximum offset, the endpoint cannot send exceeds the peer's maximum offset, the endpoint cannot send
additional data on stream 0 until the peer has sent a MAX_STREAM_DATA additional data on stream 0 until the peer has sent a MAX_STREAM_DATA
frame indicating a larger maximum offset. frame indicating a larger maximum offset.
11.2. Stream Limit Increment 10.2. Stream Limit Increment
As with flow control, this document leaves when and how many streams As with flow control, this document leaves when and how many streams
to make available to a peer via MAX_STREAM_ID to implementations, but to make available to a peer via MAX_STREAM_ID to implementations, but
offers a few considerations. MAX_STREAM_ID frames constitute minimal offers a few considerations. MAX_STREAM_ID frames constitute minimal
overhead, while withholding MAX_STREAM_ID frames can prevent the peer overhead, while withholding MAX_STREAM_ID frames can prevent the peer
from using the available parallelism. from using the available parallelism.
Implementations will likely want to increase the maximum stream ID as Implementations will likely want to increase the maximum stream ID as
peer-initiated streams close. A receiver MAY also advance the peer-initiated streams close. A receiver MAY also advance the
maximum stream ID based on current activity, system conditions, and maximum stream ID based on current activity, system conditions, and
other environmental factors. other environmental factors.
11.2.1. Blocking on Flow Control 10.2.1. Blocking on Flow Control
If a sender does not receive a MAX_DATA or MAX_STREAM_DATA frame when If a sender does not receive a MAX_DATA or MAX_STREAM_DATA frame when
it has run out of flow control credit, the sender will be blocked and it has run out of flow control credit, the sender will be blocked and
SHOULD send a BLOCKED or STREAM_BLOCKED frame. These frames are SHOULD send a BLOCKED or STREAM_BLOCKED frame. These frames are
expected to be useful for debugging at the receiver; they do not expected to be useful for debugging at the receiver; they do not
require any other action. A receiver SHOULD NOT wait for a BLOCKED require any other action. A receiver SHOULD NOT wait for a BLOCKED
or STREAM_BLOCKED frame before sending MAX_DATA or MAX_STREAM_DATA, or STREAM_BLOCKED frame before sending MAX_DATA or MAX_STREAM_DATA,
since doing so will mean that a sender is unable to send for an since doing so will mean that a sender is unable to send for an
entire round trip. entire round trip.
For smooth operation of the congestion controller, it is generally For smooth operation of the congestion controller, it is generally
considered best to not let the sender go into quiescence if considered best to not let the sender go into quiescence if
avoidable. To avoid blocking a sender, and to reasonably account for avoidable. To avoid blocking a sender, and to reasonably account for
the possibiity of loss, a receiver should send a MAX_DATA or the possibiity of loss, a receiver should send a MAX_DATA or
MAX_STREAM_DATA frame at least two roundtrips before it expects the MAX_STREAM_DATA frame at least two round trips before it expects the
sender to get blocked. sender to get blocked.
A sender sends a single BLOCKED or STREAM_BLOCKED frame only once A sender sends a single BLOCKED or STREAM_BLOCKED frame only once
when it reaches a data limit. A sender SHOULD NOT send multiple when it reaches a data limit. A sender SHOULD NOT send multiple
BLOCKED or STREAM_BLOCKED frames for the same data limit, unless the BLOCKED or STREAM_BLOCKED frames for the same data limit, unless the
original frame is determined to be lost. Another BLOCKED or original frame is determined to be lost. Another BLOCKED or
STREAM_BLOCKED frame can be sent after the data limit is increased. STREAM_BLOCKED frame can be sent after the data limit is increased.
11.3. Stream Final Offset 10.3. Stream Final Offset
The final offset is the count of the number of octets that are The final offset is the count of the number of octets that are
transmitted on a stream. For a stream that is reset, the final transmitted on a stream. For a stream that is reset, the final
offset is carried explicitly in a RST_STREAM frame. Otherwise, the offset is carried explicitly in a RST_STREAM frame. Otherwise, the
final offset is the offset of the end of the data carried in a STREAM final offset is the offset of the end of the data carried in a STREAM
frame marked with a FIN flag, or 0 in the case of incoming frame marked with a FIN flag, or 0 in the case of incoming
unidirectional streams. unidirectional streams.
An endpoint will know the final offset for a stream when the receive An endpoint will know the final offset for a stream when the receive
stream enters the "Size Known" or "Reset Recvd" state. stream enters the "Size Known" or "Reset Recvd" state.
An endpoint MUST NOT send data on a stream at or beyond the final An endpoint MUST NOT send data on a stream at or beyond the final
offset. offset.
Once a final offset for a stream is known, it cannot change. If a Once a final offset for a stream is known, it cannot change. If a
RST_STREAM or STREAM frame causes the final offset to change for a RST_STREAM or STREAM frame causes the final offset to change for a
stream, an endpoint SHOULD respond with a FINAL_OFFSET_ERROR error stream, an endpoint SHOULD respond with a FINAL_OFFSET_ERROR error
(see Section 12). A receiver SHOULD treat receipt of data at or (see Section 11). A receiver SHOULD treat receipt of data at or
beyond the final offset as a FINAL_OFFSET_ERROR error, even after a beyond the final offset as a FINAL_OFFSET_ERROR error, even after a
stream is closed. Generating these errors is not mandatory, but only stream is closed. Generating these errors is not mandatory, but only
because requiring that an endpoint generate these errors also means because requiring that an endpoint generate these errors also means
that the endpoint needs to maintain the final offset state for closed that the endpoint needs to maintain the final offset state for closed
streams, which could mean a significant state commitment. streams, which could mean a significant state commitment.
12. Error Handling 11. Error Handling
An endpoint that detects an error SHOULD signal the existence of that An endpoint that detects an error SHOULD signal the existence of that
error to its peer. Errors can affect an entire connection (see error to its peer. Both transport-level and application-level errors
Section 12.1), or a single stream (see Section 12.2). can affect an entire connection (see Section 11.1), while only
application-level errors can be isolated to a single stream (see
Section 11.2).
The most appropriate error code (Section 12.3) SHOULD be included in The most appropriate error code (Section 11.3) SHOULD be included in
the frame that signals the error. Where this specification the frame that signals the error. Where this specification
identifies error conditions, it also identifies the error code that identifies error conditions, it also identifies the error code that
is used. is used.
A stateless reset (Section 7.9.4) is not suitable for any error that A stateless reset (Section 6.9.4) is not suitable for any error that
can be signaled with a CONNECTION_CLOSE, APPLICATION_CLOSE, or can be signaled with a CONNECTION_CLOSE, APPLICATION_CLOSE, or
RST_STREAM frame. A stateless reset MUST NOT be used by an endpoint RST_STREAM frame. A stateless reset MUST NOT be used by an endpoint
that has the state necessary to send a frame on the connection. that has the state necessary to send a frame on the connection.
12.1. Connection Errors 11.1. Connection Errors
Errors that result in the connection being unusable, such as an Errors that result in the connection being unusable, such as an
obvious violation of protocol semantics or corruption of state that obvious violation of protocol semantics or corruption of state that
affects an entire connection, MUST be signaled using a affects an entire connection, MUST be signaled using a
CONNECTION_CLOSE or APPLICATION_CLOSE frame (Section 8.4, CONNECTION_CLOSE or APPLICATION_CLOSE frame (Section 7.4,
Section 8.5). An endpoint MAY close the connection in this manner Section 7.5). An endpoint MAY close the connection in this manner
even if the error only affects a single stream. even if the error only affects a single stream.
Application protocols can signal application-specific protocol errors Application protocols can signal application-specific protocol errors
using the APPLICATION_CLOSE frame. Errors that are specific to the using the APPLICATION_CLOSE frame. Errors that are specific to the
transport, including all those described in this document, are transport, including all those described in this document, are
carried in a CONNECTION_CLOSE frame. Other than the type of error carried in a CONNECTION_CLOSE frame. Other than the type of error
code they carry, these frames are identical in format and semantics. code they carry, these frames are identical in format and semantics.
A CONNECTION_CLOSE or APPLICATION_CLOSE frame could be sent in a A CONNECTION_CLOSE or APPLICATION_CLOSE frame could be sent in a
packet that is lost. An endpoint SHOULD be prepared to retransmit a packet that is lost. An endpoint SHOULD be prepared to retransmit a
packet containing either frame type if it receives more packets on a packet containing either frame type if it receives more packets on a
terminated connection. Limiting the number of retransmissions and terminated connection. Limiting the number of retransmissions and
the time over which this final packet is sent limits the effort the time over which this final packet is sent limits the effort
expended on terminated connections. expended on terminated connections.
An endpoint that chooses not to retransmit packets containing An endpoint that chooses not to retransmit packets containing
CONNECTION_CLOSE or APPLICATION_CLOSE risks a peer missing the first CONNECTION_CLOSE or APPLICATION_CLOSE risks a peer missing the first
such packet. The only mechanism available to an endpoint that such packet. The only mechanism available to an endpoint that
continues to receive data for a terminated connection is to use the continues to receive data for a terminated connection is to use the
stateless reset process (Section 7.9.4). stateless reset process (Section 6.9.4).
An endpoint that receives an invalid CONNECTION_CLOSE or An endpoint that receives an invalid CONNECTION_CLOSE or
APPLICATION_CLOSE frame MUST NOT signal the existence of the error to APPLICATION_CLOSE frame MUST NOT signal the existence of the error to
its peer. its peer.
12.2. Stream Errors 11.2. Stream Errors
If the error affects a single stream, but otherwise leaves the If an application-level error affects a single stream, but otherwise
connection in a recoverable state, the endpoint can send a RST_STREAM leaves the connection in a recoverable state, the endpoint can send a
frame (Section 8.3) with an appropriate error code to terminate just RST_STREAM frame (Section 7.3) with an appropriate error code to
the affected stream. terminate just the affected stream.
Stream 0 is critical to the functioning of the entire connection. If Stream 0 is critical to the functioning of the entire connection. If
stream 0 is closed with either a RST_STREAM or STREAM frame bearing stream 0 is closed with either a RST_STREAM or STREAM frame bearing
the FIN flag, an endpoint MUST generate a connection error of type the FIN flag, an endpoint MUST generate a connection error of type
PROTOCOL_VIOLATION. PROTOCOL_VIOLATION.
RST_STREAM MUST be instigated by the application and MUST carry an Other than STOPPING (Section 9.3), RST_STREAM MUST be instigated by
application error code. Resetting a stream without knowledge of the the application and MUST carry an application error code. Resetting
application protocol could cause the protocol to enter an a stream without knowledge of the application protocol could cause
unrecoverable state. Application protocols might require certain the protocol to enter an unrecoverable state. Application protocols
streams to be reliably delivered in order to guarantee consistent might require certain streams to be reliably delivered in order to
state between endpoints. guarantee consistent state between endpoints.
12.3. Transport Error Codes 11.3. Transport Error Codes
QUIC error codes are 16-bit unsigned integers. QUIC error codes are 16-bit unsigned integers.
This section lists the defined QUIC transport error codes that may be This section lists the defined QUIC transport error codes that may be
used in a CONNECTION_CLOSE frame. These errors apply to the entire used in a CONNECTION_CLOSE frame. These errors apply to the entire
connection. connection.
NO_ERROR (0x0): An endpoint uses this with CONNECTION_CLOSE to NO_ERROR (0x0): An endpoint uses this with CONNECTION_CLOSE to
signal that the connection is being closed abruptly in the absence signal that the connection is being closed abruptly in the absence
of any error. of any error.
INTERNAL_ERROR (0x1): The endpoint encountered an internal error and INTERNAL_ERROR (0x1): The endpoint encountered an internal error and
cannot continue with the connection. cannot continue with the connection.
SERVER_BUSY (0x2): The server is currently busy and does not accept SERVER_BUSY (0x2): The server is currently busy and does not accept
any new connections. any new connections.
FLOW_CONTROL_ERROR (0x3): An endpoint received more data than it FLOW_CONTROL_ERROR (0x3): An endpoint received more data than it
permitted in its advertised data limits (see Section 11). permitted in its advertised data limits (see Section 10).
STREAM_ID_ERROR (0x4): An endpoint received a frame for a stream STREAM_ID_ERROR (0x4): An endpoint received a frame for a stream
identifier that exceeded its advertised maximum stream ID. identifier that exceeded its advertised maximum stream ID.
STREAM_STATE_ERROR (0x5): An endpoint received a frame for a stream STREAM_STATE_ERROR (0x5): An endpoint received a frame for a stream
that was not in a state that permitted that frame (see that was not in a state that permitted that frame (see
Section 10.2). Section 9.2).
FINAL_OFFSET_ERROR (0x6): An endpoint received a STREAM frame FINAL_OFFSET_ERROR (0x6): An endpoint received a STREAM frame
containing data that exceeded the previously established final containing data that exceeded the previously established final
offset. Or an endpoint received a RST_STREAM frame containing a offset. Or an endpoint received a RST_STREAM frame containing a
final offset that was lower than the maximum offset of data that final offset that was lower than the maximum offset of data that
was already received. Or an endpoint received a RST_STREAM frame was already received. Or an endpoint received a RST_STREAM frame
containing a different final offset to the one already containing a different final offset to the one already
established. established.
FRAME_FORMAT_ERROR (0x7): An endpoint received a frame that was FRAME_FORMAT_ERROR (0x7): An endpoint received a frame that was
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UNSOLICITED_PATH_RESPONSE (0xB): An endpoint received a UNSOLICITED_PATH_RESPONSE (0xB): An endpoint received a
PATH_RESPONSE frame that did not correspond to any PATH_CHALLENGE PATH_RESPONSE frame that did not correspond to any PATH_CHALLENGE
frame that it previously sent. frame that it previously sent.
FRAME_ERROR (0x1XX): An endpoint detected an error in a specific FRAME_ERROR (0x1XX): An endpoint detected an error in a specific
frame type. The frame type is included as the last octet of the frame type. The frame type is included as the last octet of the
error code. For example, an error in a MAX_STREAM_ID frame would error code. For example, an error in a MAX_STREAM_ID frame would
be indicated with the code (0x106). be indicated with the code (0x106).
Codes for errors occuring when TLS is used for the crypto handshake Codes for errors occuring when TLS is used for the crypto handshake
are defined in Section 11 of [QUIC-TLS]. See Section 14.2 for are defined in Section 11 of [QUIC-TLS]. See Section 13.2 for
details of registering new error codes. details of registering new error codes.
12.4. Application Protocol Error Codes 11.4. Application Protocol Error Codes
Application protocol error codes are 16-bit unsigned integers, but Application protocol error codes are 16-bit unsigned integers, but
the management of application error codes are left to application the management of application error codes are left to application
protocols. Application protocol error codes are used for the protocols. Application protocol error codes are used for the
RST_STREAM (Section 8.3) and APPLICATION_CLOSE (Section 8.5) frames. RST_STREAM (Section 7.3) and APPLICATION_CLOSE (Section 7.5) frames.
There is no restriction on the use of the 16-bit error code space for There is no restriction on the use of the 16-bit error code space for
application protocols. However, QUIC reserves the error code with a application protocols. However, QUIC reserves the error code with a
value of 0 to mean STOPPING. The application error code of STOPPING value of 0 to mean STOPPING. The application error code of STOPPING
(0) is used by the transport to cancel a stream in response to (0) is used by the transport to cancel a stream in response to
receipt of a STOP_SENDING frame. receipt of a STOP_SENDING frame.
13. Security and Privacy Considerations 12. Security and Privacy Considerations
13.1. Spoofed ACK Attack
12.1. Spoofed ACK Attack
An attacker might be able to receive an address validation token An attacker might be able to receive an address validation token
(Section 7.6) from the server and then release the IP address it used (Section 6.6) from the server and then release the IP address it used
to acquire that token. The attacker may, in the future, spoof this to acquire that token. The attacker may, in the future, spoof this
same address (which now presumably addresses a different endpoint), same address (which now presumably addresses a different endpoint),
and initiate a 0-RTT connection with a server on the victim's behalf. and initiate a 0-RTT connection with a server on the victim's behalf.
The attacker can then spoof ACK frames to the server which cause the The attacker can then spoof ACK frames to the server which cause the
server to send excessive amounts of data toward the new owner of the server to send excessive amounts of data toward the new owner of the
IP address. IP address.
There are two possible mitigations to this attack. The simplest one There are two possible mitigations to this attack. The simplest one
is that a server can unilaterally create a gap in packet-number is that a server can unilaterally create a gap in packet-number
space. In the non-attack scenario, the client will send an ACK frame space. In the non-attack scenario, the client will send an ACK frame
skipping to change at page 86, line 33 skipping to change at page 89, line 42
The second mitigation is that the server can require that The second mitigation is that the server can require that
acknowledgments for sent packets match the encryption level of the acknowledgments for sent packets match the encryption level of the
sent packet. This mitigation is useful if the connection has an sent packet. This mitigation is useful if the connection has an
ephemeral forward-secure key that is generated and used for every new ephemeral forward-secure key that is generated and used for every new
connection. If a packet sent is protected with a forward-secure key, connection. If a packet sent is protected with a forward-secure key,
then any acknowledgments that are received for them MUST also be then any acknowledgments that are received for them MUST also be
forward-secure protected. Since the attacker will not have the forward-secure protected. Since the attacker will not have the
forward secure key, the attacker will not be able to generate forward secure key, the attacker will not be able to generate
forward-secure protected packets with ACK frames. forward-secure protected packets with ACK frames.
13.2. Slowloris Attacks 12.2. Optimistic ACK Attack
An endpoint that acknowledges packets it has not received might cause
a congestion controller to permit sending at rates beyond what the
network supports. An endpoint MAY skip packet numbers when sending
packets to detect this behavior. An endpoint can then immediately
close the connection with a connection error of type
PROTOCOL_VIOLATION (see Section 6.9.3).
12.3. Slowloris Attacks
The attacks commonly known as Slowloris [SLOWLORIS] try to keep many The attacks commonly known as Slowloris [SLOWLORIS] try to keep many
connections to the target endpoint open and hold them open as long as connections to the target endpoint open and hold them open as long as
possible. These attacks can be executed against a QUIC endpoint by possible. These attacks can be executed against a QUIC endpoint by
generating the minimum amount of activity necessary to avoid being generating the minimum amount of activity necessary to avoid being
closed for inactivity. This might involve sending small amounts of closed for inactivity. This might involve sending small amounts of
data, gradually opening flow control windows in order to control the data, gradually opening flow control windows in order to control the
sender rate, or manufacturing ACK frames that simulate a high loss sender rate, or manufacturing ACK frames that simulate a high loss
rate. rate.
QUIC deployments SHOULD provide mitigations for the Slowloris QUIC deployments SHOULD provide mitigations for the Slowloris
attacks, such as increasing the maximum number of clients the server attacks, such as increasing the maximum number of clients the server
will allow, limiting the number of connections a single IP address is will allow, limiting the number of connections a single IP address is
allowed to make, imposing restrictions on the minimum transfer speed allowed to make, imposing restrictions on the minimum transfer speed
a connection is allowed to have, and restricting the length of time a connection is allowed to have, and restricting the length of time
an endpoint is allowed to stay connected. an endpoint is allowed to stay connected.
13.3. Stream Fragmentation and Reassembly Attacks 12.4. Stream Fragmentation and Reassembly Attacks
An adversarial endpoint might intentionally fragment the data on An adversarial endpoint might intentionally fragment the data on
stream buffers in order to cause disproportionate memory commitment. stream buffers in order to cause disproportionate memory commitment.
An adversarial endpoint could open a stream and send some STREAM An adversarial endpoint could open a stream and send some STREAM
frames containing arbitrary fragments of the stream content. frames containing arbitrary fragments of the stream content.
The attack is mitigated if flow control windows correspond to The attack is mitigated if flow control windows correspond to
available memory. However, some receivers will over-commit memory available memory. However, some receivers will over-commit memory
and advertise flow control offsets in the aggregate that exceed and advertise flow control offsets in the aggregate that exceed
actual available memory. The over-commitment strategy can lead to actual available memory. The over-commitment strategy can lead to
better performance when endpoints are well behaved, but renders better performance when endpoints are well behaved, but renders
endpoints vulnerable to the stream fragmentation attack. endpoints vulnerable to the stream fragmentation attack.
QUIC deployments SHOULD provide mitigations against the stream QUIC deployments SHOULD provide mitigations against the stream
fragmentation attack. Mitigations could consist of avoiding over- fragmentation attack. Mitigations could consist of avoiding over-
committing memory, delaying reassembly of STREAM frames, implementing committing memory, delaying reassembly of STREAM frames, implementing
heuristics based on the age and duration of reassembly holes, or some heuristics based on the age and duration of reassembly holes, or some
combination. combination.
13.4. Stream Commitment Attack 12.5. Stream Commitment Attack
An adversarial endpoint can open lots of streams, exhausting state on An adversarial endpoint can open lots of streams, exhausting state on
an endpoint. The adversarial endpoint could repeat the process on a an endpoint. The adversarial endpoint could repeat the process on a
large number of connections, in a manner similar to SYN flooding large number of connections, in a manner similar to SYN flooding
attacks in TCP. attacks in TCP.
Normally, clients will open streams sequentially, as explained in Normally, clients will open streams sequentially, as explained in
Section 10.1. However, when several streams are initiated at short Section 9.1. However, when several streams are initiated at short
intervals, transmission error may cause STREAM DATA frames opening intervals, transmission error may cause STREAM DATA frames opening
streams to be received out of sequence. A receiver is obligated to streams to be received out of sequence. A receiver is obligated to
open intervening streams if a higher-numbered stream ID is received. open intervening streams if a higher-numbered stream ID is received.
Thus, on a new connection, opening stream 2000001 opens 1 million Thus, on a new connection, opening stream 2000001 opens 1 million
streams, as required by the specification. streams, as required by the specification.
The number of active streams is limited by the concurrent stream The number of active streams is limited by the concurrent stream
limit transport parameter, as explained in Section 10.4. If chosen limit transport parameter, as explained in Section 9.4. If chosen
judisciously, this limit mitigates the effect of the stream judisciously, this limit mitigates the effect of the stream
commitment attack. However, setting the limit too low could affect commitment attack. However, setting the limit too low could affect
performance when applications expect to open large number of streams. performance when applications expect to open large number of streams.
14. IANA Considerations 13. IANA Considerations
14.1. QUIC Transport Parameter Registry 13.1. QUIC Transport Parameter Registry
IANA [SHALL add/has added] a registry for "QUIC Transport Parameters" IANA [SHALL add/has added] a registry for "QUIC Transport Parameters"
under a "QUIC Protocol" heading. under a "QUIC Protocol" heading.
The "QUIC Transport Parameters" registry governs a 16-bit space. The "QUIC Transport Parameters" registry governs a 16-bit space.
This space is split into two spaces that are governed by different This space is split into two spaces that are governed by different
policies. Values with the first byte in the range 0x00 to 0xfe (in policies. Values with the first byte in the range 0x00 to 0xfe (in
hexadecimal) are assigned via the Specification Required policy hexadecimal) are assigned via the Specification Required policy
[RFC8126]. Values with the first byte 0xff are reserved for Private [RFC8126]. Values with the first byte 0xff are reserved for Private
Use [RFC8126]. Use [RFC8126].
skipping to change at page 88, line 33 skipping to change at page 92, line 8
readily accessible. The expert(s) are encouraged to be biased readily accessible. The expert(s) are encouraged to be biased
towards approving registrations unless they are abusive, frivolous, towards approving registrations unless they are abusive, frivolous,
or actively harmful (not merely aesthetically displeasing, or or actively harmful (not merely aesthetically displeasing, or
architecturally dubious). architecturally dubious).
The initial contents of this registry are shown in Table 7. The initial contents of this registry are shown in Table 7.
+--------+----------------------------+---------------+ +--------+----------------------------+---------------+
| Value | Parameter Name | Specification | | Value | Parameter Name | Specification |
+--------+----------------------------+---------------+ +--------+----------------------------+---------------+
| 0x0000 | initial_max_stream_data | Section 7.4.1 | | 0x0000 | initial_max_stream_data | Section 6.4.1 |
| | | |
| 0x0001 | initial_max_data | Section 7.4.1 |
| | | | | | | |
| 0x0002 | initial_max_stream_id_bidi | Section 7.4.1 | | 0x0001 | initial_max_data | Section 6.4.1 |
| | | | | | | |
| 0x0003 | idle_timeout | Section 7.4.1 | | 0x0002 | initial_max_stream_id_bidi | Section 6.4.1 |
| | | | | | | |
| 0x0004 | omit_connection_id | Section 7.4.1 | | 0x0003 | idle_timeout | Section 6.4.1 |
| | | | | | | |
| 0x0005 | max_packet_size | Section 7.4.1 | | 0x0005 | max_packet_size | Section 6.4.1 |
| | | | | | | |
| 0x0006 | stateless_reset_token | Section 7.4.1 | | 0x0006 | stateless_reset_token | Section 6.4.1 |
| | | | | | | |
| 0x0007 | ack_delay_exponent | Section 7.4.1 | | 0x0007 | ack_delay_exponent | Section 6.4.1 |
| | | | | | | |
| 0x0008 | initial_max_stream_id_uni | Section 7.4.1 | | 0x0008 | initial_max_stream_id_uni | Section 6.4.1 |
+--------+----------------------------+---------------+ +--------+----------------------------+---------------+
Table 7: Initial QUIC Transport Parameters Entries Table 7: Initial QUIC Transport Parameters Entries
14.2. QUIC Transport Error Codes Registry 13.2. QUIC Transport Error Codes Registry
IANA [SHALL add/has added] a registry for "QUIC Transport Error IANA [SHALL add/has added] a registry for "QUIC Transport Error
Codes" under a "QUIC Protocol" heading. Codes" under a "QUIC Protocol" heading.
The "QUIC Transport Error Codes" registry governs a 16-bit space. The "QUIC Transport Error Codes" registry governs a 16-bit space.
This space is split into two spaces that are governed by different This space is split into two spaces that are governed by different
policies. Values with the first byte in the range 0x00 to 0xfe (in policies. Values with the first byte in the range 0x00 to 0xfe (in
hexadecimal) are assigned via the Specification Required policy hexadecimal) are assigned via the Specification Required policy
[RFC8126]. Values with the first byte 0xff are reserved for Private [RFC8126]. Values with the first byte 0xff are reserved for Private
Use [RFC8126]. Use [RFC8126].
skipping to change at page 89, line 38 skipping to change at page 93, line 13
the value. the value.
The initial contents of this registry are shown in Table 8. Note The initial contents of this registry are shown in Table 8. Note
that FRAME_ERROR takes the range from 0x100 to 0x1FF and private use that FRAME_ERROR takes the range from 0x100 to 0x1FF and private use
occupies the range from 0xFE00 to 0xFFFF. occupies the range from 0xFE00 to 0xFFFF.
+-----------+------------------------+---------------+--------------+ +-----------+------------------------+---------------+--------------+
| Value | Error | Description | Specificatio | | Value | Error | Description | Specificatio |
| | | | n | | | | | n |
+-----------+------------------------+---------------+--------------+ +-----------+------------------------+---------------+--------------+
| 0x0 | NO_ERROR | No error | Section 12.3 | | 0x0 | NO_ERROR | No error | Section 11.3 |
| | | | | | | | | |
| 0x1 | INTERNAL_ERROR | Implementatio | Section 12.3 | | 0x1 | INTERNAL_ERROR | Implementatio | Section 11.3 |
| | | n error | | | | | n error | |
| | | | | | | | | |
| 0x2 | SERVER_BUSY | Server | Section 12.3 | | 0x2 | SERVER_BUSY | Server | Section 11.3 |
| | | currently | | | | | currently | |
| | | busy | | | | | busy | |
| | | | | | | | | |
| 0x3 | FLOW_CONTROL_ERROR | Flow control | Section 12.3 | | 0x3 | FLOW_CONTROL_ERROR | Flow control | Section 11.3 |
| | | error | | | | | error | |
| | | | | | | | | |
| 0x4 | STREAM_ID_ERROR | Invalid | Section 12.3 | | 0x4 | STREAM_ID_ERROR | Invalid | Section 11.3 |
| | | stream ID | | | | | stream ID | |
| | | | | | | | | |
| 0x5 | STREAM_STATE_ERROR | Frame | Section 12.3 | | 0x5 | STREAM_STATE_ERROR | Frame | Section 11.3 |
| | | received in | | | | | received in | |
| | | invalid | | | | | invalid | |
| | | stream state | | | | | stream state | |
| | | | | | | | | |
| 0x6 | FINAL_OFFSET_ERROR | Change to | Section 12.3 | | 0x6 | FINAL_OFFSET_ERROR | Change to | Section 11.3 |
| | | final stream | | | | | final stream | |
| | | offset | | | | | offset | |
| | | | | | | | | |
| 0x7 | FRAME_FORMAT_ERROR | Generic frame | Section 12.3 | | 0x7 | FRAME_FORMAT_ERROR | Generic frame | Section 11.3 |
| | | format error | | | | | format error | |
| | | | | | | | | |
| 0x8 | TRANSPORT_PARAMETER_ER | Error in | Section 12.3 | | 0x8 | TRANSPORT_PARAMETER_ER | Error in | Section 11.3 |
| | ROR | transport | | | | ROR | transport | |
| | | parameters | | | | | parameters | |
| | | | | | | | | |
| 0x9 | VERSION_NEGOTIATION_ER | Version | Section 12.3 | | 0x9 | VERSION_NEGOTIATION_ER | Version | Section 11.3 |
| | ROR | negotiation | | | | ROR | negotiation | |
| | | failure | | | | | failure | |
| | | | | | | | | |
| 0xA | PROTOCOL_VIOLATION | Generic | Section 12.3 | | 0xA | PROTOCOL_VIOLATION | Generic | Section 11.3 |
| | | protocol | | | | | protocol | |
| | | violation | | | | | violation | |
| | | | | | | | | |
| 0xB | UNSOLICITED_PATH_RESPO | Unsolicited | Section 12.3 | | 0xB | UNSOLICITED_PATH_RESPO | Unsolicited | Section 11.3 |
| | NSE | PATH_RESPONSE | | | | NSE | PATH_RESPONSE | |
| | | frame | | | | | frame | |
| | | | | | | | | |
| 0x100-0x1 | FRAME_ERROR | Specific | Section 12.3 | | 0x100-0x1 | FRAME_ERROR | Specific | Section 11.3 |
| FF | | frame format | | | FF | | frame format | |
| | | error | | | | | error | |
+-----------+------------------------+---------------+--------------+ +-----------+------------------------+---------------+--------------+
Table 8: Initial QUIC Transport Error Codes Entries Table 8: Initial QUIC Transport Error Codes Entries
15. References 14. References
15.1. Normative References 14.1. Normative References
[I-D.ietf-tls-tls13] [I-D.ietf-tls-tls13]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", draft-ietf-tls-tls13-21 (work in progress), Version 1.3", draft-ietf-tls-tls13-21 (work in progress),
July 2017. July 2017.
[PLPMTUD] Mathis, M. and J. Heffner, "Packetization Layer Path MTU [PLPMTUD] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007,
<https://www.rfc-editor.org/info/rfc4821>. <https://www.rfc-editor.org/info/rfc4821>.
skipping to change at page 91, line 17 skipping to change at page 94, line 39
<https://www.rfc-editor.org/info/rfc1191>. <https://www.rfc-editor.org/info/rfc1191>.
[PMTUDv6] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed., [PMTUDv6] McCann, J., Deering, S., Mogul, J., and R. Hinden, Ed.,
"Path MTU Discovery for IP version 6", STD 87, RFC 8201, "Path MTU Discovery for IP version 6", STD 87, RFC 8201,
DOI 10.17487/RFC8201, July 2017, DOI 10.17487/RFC8201, July 2017,
<https://www.rfc-editor.org/info/rfc8201>. <https://www.rfc-editor.org/info/rfc8201>.
[QUIC-RECOVERY] [QUIC-RECOVERY]
Iyengar, J., Ed. and I. Swett, Ed., "QUIC Loss Detection Iyengar, J., Ed. and I. Swett, Ed., "QUIC Loss Detection
and Congestion Control", draft-ietf-quic-recovery-10 (work and Congestion Control", draft-ietf-quic-recovery-10 (work
in progress), March 2018. in progress), April 2018.
[QUIC-TLS] [QUIC-TLS]
Thomson, M., Ed. and S. Turner, Ed., "Using Transport Thomson, M., Ed. and S. Turner, Ed., "Using Transport
Layer Security (TLS) to Secure QUIC", draft-ietf-quic- Layer Security (TLS) to Secure QUIC", draft-ietf-quic-
tls-10 (work in progress), March 2018. tls-10 (work in progress), April 2018.
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990, DOI 10.17487/RFC1191, November 1990,
<https://www.rfc-editor.org/info/rfc1191>. <https://www.rfc-editor.org/info/rfc1191>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
skipping to change at page 92, line 9 skipping to change at page 95, line 32
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
15.2. Informative References 14.2. Informative References
[EARLY-DESIGN] [EARLY-DESIGN]
Roskind, J., "QUIC: Multiplexed Transport Over UDP", Roskind, J., "QUIC: Multiplexed Transport Over UDP",
December 2013, <https://goo.gl/dMVtFi>. December 2013, <https://goo.gl/dMVtFi>.
[HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext [HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540, Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015, DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>. <https://www.rfc-editor.org/info/rfc7540>.
[QUIC-INVARIANTS] [QUIC-INVARIANTS]
Thomson, M., "Version-Independent Properties of QUIC", Thomson, M., "Version-Independent Properties of QUIC",
draft-ietf-quic-invariants-00 (work in progress), March draft-ietf-quic-invariants-01 (work in progress), April
2018. 2018.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104, Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997, DOI 10.17487/RFC2104, February 1997,
<https://www.rfc-editor.org/info/rfc2104>. <https://www.rfc-editor.org/info/rfc2104>.
[RFC2360] Scott, G., "Guide for Internet Standards Writers", BCP 22, [RFC2360] Scott, G., "Guide for Internet Standards Writers", BCP 22,
RFC 2360, DOI 10.17487/RFC2360, June 1998, RFC 2360, DOI 10.17487/RFC2360, June 1998,
<https://www.rfc-editor.org/info/rfc2360>. <https://www.rfc-editor.org/info/rfc2360>.
skipping to change at page 92, line 44 skipping to change at page 96, line 19
[RFC4787] Audet, F., Ed. and C. Jennings, "Network Address [RFC4787] Audet, F., Ed. and C. Jennings, "Network Address
Translation (NAT) Behavioral Requirements for Unicast Translation (NAT) Behavioral Requirements for Unicast
UDP", BCP 127, RFC 4787, DOI 10.17487/RFC4787, January UDP", BCP 127, RFC 4787, DOI 10.17487/RFC4787, January
2007, <https://www.rfc-editor.org/info/rfc4787>. 2007, <https://www.rfc-editor.org/info/rfc4787>.
[RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand [RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand
Key Derivation Function (HKDF)", RFC 5869, Key Derivation Function (HKDF)", RFC 5869,
DOI 10.17487/RFC5869, May 2010, DOI 10.17487/RFC5869, May 2010,
<https://www.rfc-editor.org/info/rfc5869>. <https://www.rfc-editor.org/info/rfc5869>.
[RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
"TCP Extensions for Multipath Operation with Multiple
Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,
<https://www.rfc-editor.org/info/rfc6824>.
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol "Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301, Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, <https://www.rfc-editor.org/info/rfc7301>. July 2014, <https://www.rfc-editor.org/info/rfc7301>.
[SLOWLORIS] [SLOWLORIS]
RSnake Hansen, R., "Welcome to Slowloris...", June 2009, RSnake Hansen, R., "Welcome to Slowloris...", June 2009,
<https://web.archive.org/web/20150315054838/ <https://web.archive.org/web/20150315054838/
http://ha.ckers.org/slowloris/>. http://ha.ckers.org/slowloris/>.
[SST] Ford, B., "Structured streams", ACM SIGCOMM Computer [SST] Ford, B., "Structured streams", ACM SIGCOMM Computer
Communication Review Vol. 37, pp. 361, Communication Review Vol. 37, pp. 361,
DOI 10.1145/1282427.1282421, October 2007. DOI 10.1145/1282427.1282421, October 2007.
15.3. URIs 14.3. URIs
[1] https://mailarchive.ietf.org/arch/search/?email_list=quic [1] https://mailarchive.ietf.org/arch/search/?email_list=quic
[2] https://github.com/quicwg [2] https://github.com/quicwg
[3] https://github.com/quicwg/base-drafts/labels/-transport [3] https://github.com/quicwg/base-drafts/labels/-transport
[4] https://github.com/quicwg/base-drafts/wiki/QUIC-Versions [4] https://github.com/quicwg/base-drafts/wiki/QUIC-Versions
Appendix A. Contributors Appendix A. Contributors
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discussions and public ones on the quic@ietf.org and proto- discussions and public ones on the quic@ietf.org and proto-
quic@chromium.org mailing lists. Our thanks to all. quic@chromium.org mailing lists. Our thanks to all.
Appendix C. Change Log Appendix C. Change Log
*RFC Editor's Note:* Please remove this section prior to *RFC Editor's Note:* Please remove this section prior to
publication of a final version of this document. publication of a final version of this document.
Issue and pull request numbers are listed with a leading octothorp. Issue and pull request numbers are listed with a leading octothorp.
C.1. Since draft-ietf-quic-transport-09 C.1. Since draft-ietf-quic-transport-10
o Swap payload length and packed number fields in long header
(#1294)
o Clarified that CONNECTION_CLOSE is allowed in Handshake packet
(#1274)
o Spin bit reserved (#1283)
o Coalescing multiple QUIC packets in a UDP datagram (#1262, #1285)
o A more complete connection migration (#1249)
o Refine opportunistic ACK defense text (#305, #1030, #1185)
o A Stateless Reset Token isn't mandatory (#818, #1191)
o Removed implicit stream opening (#896, #1193)
o An empty STREAM frame can be used to open a stream without sending
data (#901, #1194)
o Define stream counts in transport parameters rather than a maximum
stream ID (#1023, #1065)
o STOP_SENDING is now prohibited before streams are used (#1050)
o Recommend including ACK in Retry packets and allow PADDING (#1067,
#882)
o Endpoints now become closing after an idle timeout (#1178, #1179)
o Remove implication that Version Negotiation is sent when a packet
of the wrong version is received (#1197)
C.2. Since draft-ietf-quic-transport-09
o Added PATH_CHALLENGE and PATH_RESPONSE frames to replace PING with o Added PATH_CHALLENGE and PATH_RESPONSE frames to replace PING with
Data and PONG frame. Changed ACK frame type from 0x0e to 0x0d. Data and PONG frame. Changed ACK frame type from 0x0e to 0x0d.
(#1091, #1086) (#1091, #725, #1086)
o A server can now only send 3 packets without validating the client o A server can now only send 3 packets without validating the client
address (#38, #1090) address (#38, #1090)
o Delivery order of stream data is no longer strongly specified o Delivery order of stream data is no longer strongly specified
(#252, #1070) (#252, #1070)
o Rework of packet handling and version negotiation (#1038) o Rework of packet handling and version negotiation (#1038)
o Stream 0 is now exempt from flow control until the handshake o Stream 0 is now exempt from flow control until the handshake
completes (#1074, #725, #1082) completes (#1074, #725, #825, #1082)
o Improved retransmission rules for all frame types: information is o Improved retransmission rules for all frame types: information is
retransmitted, not packets or frames (#463, #765, #1095, #1053) retransmitted, not packets or frames (#463, #765, #1095, #1053)
o Added an error code for server busy signals (#1137) o Added an error code for server busy signals (#1137)
C.2. Since draft-ietf-quic-transport-08 o Endpoints now set the connection ID that their peer uses.
Connection IDs are variable length. Removed the
omit_connection_id transport parameter and the corresponding short
header flag. (#1089, #1052, #1146, #821, #745, #821, #1166, #1151)
C.3. Since draft-ietf-quic-transport-08
o Clarified requirements for BLOCKED usage (#65, #924) o Clarified requirements for BLOCKED usage (#65, #924)
o BLOCKED frame now includes reason for blocking (#452, #924, #927, o BLOCKED frame now includes reason for blocking (#452, #924, #927,
#928) #928)
o GAP limitation in ACK Frame (#613) o GAP limitation in ACK Frame (#613)
o Improved PMTUD description (#614, #1036) o Improved PMTUD description (#614, #1036)
o Clarified stream state machine (#634, #662, #894) o Clarified stream state machine (#634, #662, #743, #894)
o Reserved versions don't need to be generated deterministically o Reserved versions don't need to be generated deterministically
(#831, #931) (#831, #931)
o You don't always need the draining period (#871) o You don't always need the draining period (#871)
o Stateless reset clarified as version-specific (#930, #986) o Stateless reset clarified as version-specific (#930, #986)
o initial_max_stream_id_x transport parameters are optional (#970, o initial_max_stream_id_x transport parameters are optional (#970,
#971) #971)
o Ack Delay assumes a default value during the handshake (#1007, o Ack Delay assumes a default value during the handshake (#1007,
#1009) #1009)
o Removed transport parameters from NewSessionTicket (#1015) o Removed transport parameters from NewSessionTicket (#1015)
C.3. Since draft-ietf-quic-transport-07 C.4. Since draft-ietf-quic-transport-07
o The long header now has version before packet number (#926, #939) o The long header now has version before packet number (#926, #939)
o Rename and consolidate packet types (#846, #822, #847) o Rename and consolidate packet types (#846, #822, #847)
o Packet types are assigned new codepoints and the Connection ID o Packet types are assigned new codepoints and the Connection ID
Flag is inverted (#426, #956) Flag is inverted (#426, #956)
o Removed type for Version Negotiation and use Version 0 (#963, o Removed type for Version Negotiation and use Version 0 (#963,
#968) #968)
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o Address validation for connection migration (#161, #732, #878) o Address validation for connection migration (#161, #732, #878)
o Clearly defined retransmission rules for BLOCKED (#452, #65, #924) o Clearly defined retransmission rules for BLOCKED (#452, #65, #924)
o negotiated_version is sent in server transport parameters (#710, o negotiated_version is sent in server transport parameters (#710,
#959) #959)
o Increased the range over which packet numbers are randomized o Increased the range over which packet numbers are randomized
(#864, #850, #964) (#864, #850, #964)
C.4. Since draft-ietf-quic-transport-06 C.5. Since draft-ietf-quic-transport-06
o Replaced FNV-1a with AES-GCM for all "Cleartext" packets (#554) o Replaced FNV-1a with AES-GCM for all "Cleartext" packets (#554)
o Split error code space between application and transport (#485) o Split error code space between application and transport (#485)
o Stateless reset token moved to end (#820) o Stateless reset token moved to end (#820)
o 1-RTT-protected long header types removed (#848) o 1-RTT-protected long header types removed (#848)
o No acknowledgments during draining period (#852) o No acknowledgments during draining period (#852)
o Remove "application close" as a separate close type (#854) o Remove "application close" as a separate close type (#854)
o Remove timestamps from the ACK frame (#841) o Remove timestamps from the ACK frame (#841)
o Require transport parameters to only appear once (#792) o Require transport parameters to only appear once (#792)
C.5. Since draft-ietf-quic-transport-05 C.6. Since draft-ietf-quic-transport-05
o Stateless token is server-only (#726) o Stateless token is server-only (#726)
o Refactor section on connection termination (#733, #748, #328, o Refactor section on connection termination (#733, #748, #328,
#177) #177)
o Limit size of Version Negotiation packet (#585) o Limit size of Version Negotiation packet (#585)
o Clarify when and what to ack (#736) o Clarify when and what to ack (#736)
o Renamed STREAM_ID_NEEDED to STREAM_ID_BLOCKED o Renamed STREAM_ID_NEEDED to STREAM_ID_BLOCKED
o Clarify Keep-alive requirements (#729) o Clarify Keep-alive requirements (#729)
C.6. Since draft-ietf-quic-transport-04 C.7. Since draft-ietf-quic-transport-04
o Introduce STOP_SENDING frame, RST_STREAM only resets in one o Introduce STOP_SENDING frame, RST_STREAM only resets in one
direction (#165) direction (#165)
o Removed GOAWAY; application protocols are responsible for graceful o Removed GOAWAY; application protocols are responsible for graceful
shutdown (#696) shutdown (#696)
o Reduced the number of error codes (#96, #177, #184, #211) o Reduced the number of error codes (#96, #177, #184, #211)
o Version validation fields can't move or change (#121) o Version validation fields can't move or change (#121)
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o Increased the maximum length of the Largest Acknowledged field in o Increased the maximum length of the Largest Acknowledged field in
ACK frames to 64 bits (#629) ACK frames to 64 bits (#629)
o truncate_connection_id is renamed to omit_connection_id (#659) o truncate_connection_id is renamed to omit_connection_id (#659)
o CONNECTION_CLOSE terminates the connection like TCP RST (#330, o CONNECTION_CLOSE terminates the connection like TCP RST (#330,
#328) #328)
o Update labels used in HKDF-Expand-Label to match TLS 1.3 (#642) o Update labels used in HKDF-Expand-Label to match TLS 1.3 (#642)
C.7. Since draft-ietf-quic-transport-03 C.8. Since draft-ietf-quic-transport-03
o Change STREAM and RST_STREAM layout o Change STREAM and RST_STREAM layout
o Add MAX_STREAM_ID settings o Add MAX_STREAM_ID settings
C.8. Since draft-ietf-quic-transport-02 C.9. Since draft-ietf-quic-transport-02
o The size of the initial packet payload has a fixed minimum (#267, o The size of the initial packet payload has a fixed minimum (#267,
#472) #472)
o Define when Version Negotiation packets are ignored (#284, #294, o Define when Version Negotiation packets are ignored (#284, #294,
#241, #143, #474) #241, #143, #474)
o The 64-bit FNV-1a algorithm is used for integrity protection of o The 64-bit FNV-1a algorithm is used for integrity protection of
unprotected packets (#167, #480, #481, #517) unprotected packets (#167, #480, #481, #517)
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linkability (#232, #491, #496) linkability (#232, #491, #496)
o Transport parameters for 0-RTT are retained from a previous o Transport parameters for 0-RTT are retained from a previous
connection (#405, #513, #512) connection (#405, #513, #512)
* A client in 0-RTT no longer required to reset excess streams * A client in 0-RTT no longer required to reset excess streams
(#425, #479) (#425, #479)
o Expanded security considerations (#440, #444, #445, #448) o Expanded security considerations (#440, #444, #445, #448)
C.9. Since draft-ietf-quic-transport-01 C.10. Since draft-ietf-quic-transport-01
o Defined short and long packet headers (#40, #148, #361) o Defined short and long packet headers (#40, #148, #361)
o Defined a versioning scheme and stable fields (#51, #361) o Defined a versioning scheme and stable fields (#51, #361)
o Define reserved version values for "greasing" negotiation (#112, o Define reserved version values for "greasing" negotiation (#112,
#278) #278)
o The initial packet number is randomized (#35, #283) o The initial packet number is randomized (#35, #283)
skipping to change at page 100, line 25 skipping to change at page 104, line 36
o Remove error code and reason phrase from GOAWAY (#352, #355) o Remove error code and reason phrase from GOAWAY (#352, #355)
o GOAWAY includes a final stream number for both directions (#347) o GOAWAY includes a final stream number for both directions (#347)
o Error codes for RST_STREAM and CONNECTION_CLOSE are now at a o Error codes for RST_STREAM and CONNECTION_CLOSE are now at a
consistent offset (#249) consistent offset (#249)
o Defined priority as the responsibility of the application protocol o Defined priority as the responsibility of the application protocol
(#104, #303) (#104, #303)
C.10. Since draft-ietf-quic-transport-00 C.11. Since draft-ietf-quic-transport-00
o Replaced DIVERSIFICATION_NONCE flag with KEY_PHASE flag o Replaced DIVERSIFICATION_NONCE flag with KEY_PHASE flag
o Defined versioning o Defined versioning
o Reworked description of packet and frame layout o Reworked description of packet and frame layout
o Error code space is divided into regions for each component o Error code space is divided into regions for each component
o Use big endian for all numeric values o Use big endian for all numeric values
C.11. Since draft-hamilton-quic-transport-protocol-01 C.12. Since draft-hamilton-quic-transport-protocol-01
o Adopted as base for draft-ietf-quic-tls o Adopted as base for draft-ietf-quic-tls
o Updated authors/editors list o Updated authors/editors list
o Added IANA Considerations section o Added IANA Considerations section
o Moved Contributors and Acknowledgments to appendices o Moved Contributors and Acknowledgments to appendices
Authors' Addresses Authors' Addresses
Jana Iyengar (editor) Jana Iyengar (editor)
Fastly Fastly
Email: jri.ietf@gmail.com Email: jri.ietf@gmail.com
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