draft-ietf-quic-transport-12.txt   draft-ietf-quic-transport-13.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: November 23, 2018 Mozilla Expires: December 30, 2018 Mozilla
May 22, 2018 June 28, 2018
QUIC: A UDP-Based Multiplexed and Secure Transport QUIC: A UDP-Based Multiplexed and Secure Transport
draft-ietf-quic-transport-12 draft-ietf-quic-transport-13
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 . . . . . . . . . . . . . . . . . 6 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 6
2.1. Notational Conventions . . . . . . . . . . . . . . . . . 6 2.1. Notational Conventions . . . . . . . . . . . . . . . . . 7
3. Versions . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Versions . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Packet Types and Formats . . . . . . . . . . . . . . . . . . 8 4. Packet Types and Formats . . . . . . . . . . . . . . . . . . 8
4.1. Long Header . . . . . . . . . . . . . . . . . . . . . . . 8 4.1. Long Header . . . . . . . . . . . . . . . . . . . . . . . 8
4.2. Short Header . . . . . . . . . . . . . . . . . . . . . . 10 4.2. Short Header . . . . . . . . . . . . . . . . . . . . . . 11
4.3. Version Negotiation Packet . . . . . . . . . . . . . . . 12 4.3. Version Negotiation Packet . . . . . . . . . . . . . . . 12
4.4. Cryptographic Handshake Packets . . . . . . . . . . . . . 13 4.4. Cryptographic Handshake Packets . . . . . . . . . . . . . 14
4.4.1. Initial Packet . . . . . . . . . . . . . . . . . . . 13 4.4.1. Initial Packet . . . . . . . . . . . . . . . . . . . 14
4.4.2. Retry Packet . . . . . . . . . . . . . . . . . . . . 14 4.4.2. Retry Packet . . . . . . . . . . . . . . . . . . . . 17
4.4.3. Handshake Packet . . . . . . . . . . . . . . . . . . 15 4.4.3. Handshake Packet . . . . . . . . . . . . . . . . . . 18
4.5. Protected Packets . . . . . . . . . . . . . . . . . . . . 16 4.5. Protected Packets . . . . . . . . . . . . . . . . . . . . 18
4.6. Coalescing Packets . . . . . . . . . . . . . . . . . . . 17 4.6. Coalescing Packets . . . . . . . . . . . . . . . . . . . 19
4.7. Connection ID . . . . . . . . . . . . . . . . . . . . . . 17 4.7. Connection ID Encoding . . . . . . . . . . . . . . . . . 20
4.8. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 18 4.8. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 21
5. Frames and Frame Types . . . . . . . . . . . . . . . . . . . 20 5. Frames and Frame Types . . . . . . . . . . . . . . . . . . . 23
6. Life of a Connection . . . . . . . . . . . . . . . . . . . . 22 5.1. Extension Frames . . . . . . . . . . . . . . . . . . . . 26
6.1. Matching Packets to Connections . . . . . . . . . . . . . 23 6. Life of a Connection . . . . . . . . . . . . . . . . . . . . 26
6.1.1. Client Packet Handling . . . . . . . . . . . . . . . 23 6.1. Connection ID . . . . . . . . . . . . . . . . . . . . . . 27
6.1.2. Server Packet Handling . . . . . . . . . . . . . . . 23 6.2. Matching Packets to Connections . . . . . . . . . . . . . 28
6.2. Version Negotiation . . . . . . . . . . . . . . . . . . . 24 6.2.1. Client Packet Handling . . . . . . . . . . . . . . . 28
6.2.1. Sending Version Negotiation Packets . . . . . . . . . 25 6.2.2. Server Packet Handling . . . . . . . . . . . . . . . 29
6.2.2. Handling Version Negotiation Packets . . . . . . . . 25 6.3. Version Negotiation . . . . . . . . . . . . . . . . . . . 29
6.2.3. Using Reserved Versions . . . . . . . . . . . . . . . 26 6.3.1. Sending Version Negotiation Packets . . . . . . . . . 30
6.3. Cryptographic and Transport Handshake . . . . . . . . . . 26 6.3.2. Handling Version Negotiation Packets . . . . . . . . 30
6.4. Transport Parameters . . . . . . . . . . . . . . . . . . 27 6.3.3. Using Reserved Versions . . . . . . . . . . . . . . . 31
6.4.1. Transport Parameter Definitions . . . . . . . . . . . 29 6.4. Cryptographic and Transport Handshake . . . . . . . . . . 31
6.4.2. Values of Transport Parameters for 0-RTT . . . . . . 31 6.5. Example Handshake Flows . . . . . . . . . . . . . . . . . 32
6.4.3. New Transport Parameters . . . . . . . . . . . . . . 31 6.6. Transport Parameters . . . . . . . . . . . . . . . . . . 34
6.4.4. Version Negotiation Validation . . . . . . . . . . . 32 6.6.1. Transport Parameter Definitions . . . . . . . . . . . 36
6.6.2. Values of Transport Parameters for 0-RTT . . . . . . 38
6.5. Stateless Retries . . . . . . . . . . . . . . . . . . . . 33 6.6.3. New Transport Parameters . . . . . . . . . . . . . . 38
6.6. Proof of Source Address Ownership . . . . . . . . . . . . 34 6.6.4. Version Negotiation Validation . . . . . . . . . . . 39
6.6.1. Client Address Validation Procedure . . . . . . . . . 34 6.7. Stateless Retries . . . . . . . . . . . . . . . . . . . . 40
6.6.2. Address Validation on Session Resumption . . . . . . 35 6.8. Using Explicit Congestion Notification . . . . . . . . . 40
6.6.3. Address Validation Token Integrity . . . . . . . . . 36 6.9. Proof of Source Address Ownership . . . . . . . . . . . . 42
6.7. Path Validation . . . . . . . . . . . . . . . . . . . . . 36 6.9.1. Client Address Validation Procedure . . . . . . . . . 43
6.7.1. Initiation . . . . . . . . . . . . . . . . . . . . . 37 6.9.2. Address Validation for Future Connections . . . . . . 44
6.7.2. Response . . . . . . . . . . . . . . . . . . . . . . 37 6.9.3. Address Validation Token Integrity . . . . . . . . . 44
6.7.3. Completion . . . . . . . . . . . . . . . . . . . . . 38 6.10. Path Validation . . . . . . . . . . . . . . . . . . . . . 44
6.7.4. Abandonment . . . . . . . . . . . . . . . . . . . . . 38 6.10.1. Initiation . . . . . . . . . . . . . . . . . . . . . 45
6.8. Connection Migration . . . . . . . . . . . . . . . . . . 39 6.10.2. Response . . . . . . . . . . . . . . . . . . . . . . 45
6.8.1. Probing a New Path . . . . . . . . . . . . . . . . . 39 6.10.3. Completion . . . . . . . . . . . . . . . . . . . . . 46
6.8.2. Initiating Connection Migration . . . . . . . . . . . 39 6.10.4. Abandonment . . . . . . . . . . . . . . . . . . . . 46
6.8.3. Responding to Connection Migration . . . . . . . . . 40 6.11. Connection Migration . . . . . . . . . . . . . . . . . . 47
6.8.4. Loss Detection and Congestion Control . . . . . . . . 42 6.11.1. Probing a New Path . . . . . . . . . . . . . . . . . 47
6.8.5. Privacy Implications of Connection Migration . . . . 42 6.11.2. Initiating Connection Migration . . . . . . . . . . 48
6.9. Server's Preferred Address . . . . . . . . . . . . . . . 44 6.11.3. Responding to Connection Migration . . . . . . . . . 48
6.9.1. Communicating A Preferred Address . . . . . . . . . . 44 6.11.4. Loss Detection and Congestion Control . . . . . . . 50
6.9.2. Responding to Connection Migration . . . . . . . . . 44 6.11.5. Privacy Implications of Connection Migration . . . . 51
6.9.3. Interaction of Client Migration and Preferred Address 45 6.12. Server's Preferred Address . . . . . . . . . . . . . . . 51
6.10. Connection Termination . . . . . . . . . . . . . . . . . 45 6.12.1. Communicating A Preferred Address . . . . . . . . . 52
6.10.1. Closing and Draining Connection States . . . . . . . 45 6.12.2. Responding to Connection Migration . . . . . . . . . 52
6.10.2. Idle Timeout . . . . . . . . . . . . . . . . . . . . 47 6.12.3. Interaction of Client Migration and Preferred
6.10.3. Immediate Close . . . . . . . . . . . . . . . . . . 47 Address . . . . . . . . . . . . . . . . . . . . . . 52
6.10.4. Stateless Reset . . . . . . . . . . . . . . . . . . 48 6.13. Connection Termination . . . . . . . . . . . . . . . . . 53
7. Frame Types and Formats . . . . . . . . . . . . . . . . . . . 51 6.13.1. Closing and Draining Connection States . . . . . . . 53
7.1. Variable-Length Integer Encoding . . . . . . . . . . . . 51 6.13.2. Idle Timeout . . . . . . . . . . . . . . . . . . . . 54
7.2. PADDING Frame . . . . . . . . . . . . . . . . . . . . . . 52 6.13.3. Immediate Close . . . . . . . . . . . . . . . . . . 55
7.3. RST_STREAM Frame . . . . . . . . . . . . . . . . . . . . 52 6.13.4. Stateless Reset . . . . . . . . . . . . . . . . . . 56
7.4. CONNECTION_CLOSE frame . . . . . . . . . . . . . . . . . 53 7. Frame Types and Formats . . . . . . . . . . . . . . . . . . . 59
7.5. APPLICATION_CLOSE frame . . . . . . . . . . . . . . . . . 53 7.1. Variable-Length Integer Encoding . . . . . . . . . . . . 59
7.6. MAX_DATA Frame . . . . . . . . . . . . . . . . . . . . . 54 7.2. PADDING Frame . . . . . . . . . . . . . . . . . . . . . . 60
7.7. MAX_STREAM_DATA Frame . . . . . . . . . . . . . . . . . . 54 7.3. RST_STREAM Frame . . . . . . . . . . . . . . . . . . . . 60
7.8. MAX_STREAM_ID Frame . . . . . . . . . . . . . . . . . . . 55 7.4. CONNECTION_CLOSE frame . . . . . . . . . . . . . . . . . 61
7.9. PING Frame . . . . . . . . . . . . . . . . . . . . . . . 56 7.5. APPLICATION_CLOSE frame . . . . . . . . . . . . . . . . . 62
7.10. BLOCKED Frame . . . . . . . . . . . . . . . . . . . . . . 57 7.6. MAX_DATA Frame . . . . . . . . . . . . . . . . . . . . . 62
7.11. STREAM_BLOCKED Frame . . . . . . . . . . . . . . . . . . 57 7.7. MAX_STREAM_DATA Frame . . . . . . . . . . . . . . . . . . 62
7.12. STREAM_ID_BLOCKED Frame . . . . . . . . . . . . . . . . . 58 7.8. MAX_STREAM_ID Frame . . . . . . . . . . . . . . . . . . . 63
7.13. NEW_CONNECTION_ID Frame . . . . . . . . . . . . . . . . . 58 7.9. PING Frame . . . . . . . . . . . . . . . . . . . . . . . 64
7.14. STOP_SENDING Frame . . . . . . . . . . . . . . . . . . . 59 7.10. BLOCKED Frame . . . . . . . . . . . . . . . . . . . . . . 65
7.15. ACK Frame . . . . . . . . . . . . . . . . . . . . . . . . 60 7.11. STREAM_BLOCKED Frame . . . . . . . . . . . . . . . . . . 65
7.15.1. ACK Block Section . . . . . . . . . . . . . . . . . 61 7.12. STREAM_ID_BLOCKED Frame . . . . . . . . . . . . . . . . . 66
7.15.2. Sending ACK Frames . . . . . . . . . . . . . . . . . 63 7.13. NEW_CONNECTION_ID Frame . . . . . . . . . . . . . . . . . 66
7.15.3. ACK Frames and Packet Protection . . . . . . . . . . 64 7.14. STOP_SENDING Frame . . . . . . . . . . . . . . . . . . . 68
7.16. PATH_CHALLENGE Frame . . . . . . . . . . . . . . . . . . 65 7.15. ACK Frame . . . . . . . . . . . . . . . . . . . . . . . . 68
7.17. PATH_RESPONSE Frame . . . . . . . . . . . . . . . . . . . 65 7.15.1. ACK Block Section . . . . . . . . . . . . . . . . . 70
7.18. STREAM Frames . . . . . . . . . . . . . . . . . . . . . . 65 7.15.2. Sending ACK Frames . . . . . . . . . . . . . . . . . 71
8. Packetization and Reliability . . . . . . . . . . . . . . . . 67 7.15.3. ACK Frames and Packet Protection . . . . . . . . . . 72
8.1. Packet Processing and Acknowledgment . . . . . . . . . . 67 7.16. ACK_ECN Frame . . . . . . . . . . . . . . . . . . . . . . 72
8.2. Retransmission of Information . . . . . . . . . . . . . . 68 7.17. PATH_CHALLENGE Frame . . . . . . . . . . . . . . . . . . 73
8.3. Packet Size . . . . . . . . . . . . . . . . . . . . . . . 70 7.18. PATH_RESPONSE Frame . . . . . . . . . . . . . . . . . . . 74
8.4. Path Maximum Transmission Unit . . . . . . . . . . . . . 70 7.19. NEW_TOKEN frame . . . . . . . . . . . . . . . . . . . . . 74
8.4.1. Special Considerations for PMTU Discovery . . . . . . 71 7.20. STREAM Frames . . . . . . . . . . . . . . . . . . . . . . 74
7.21. CRYPTO Frame . . . . . . . . . . . . . . . . . . . . . . 76
8. Packetization and Reliability . . . . . . . . . . . . . . . . 77
8.1. Packet Processing and Acknowledgment . . . . . . . . . . 78
8.2. Retransmission of Information . . . . . . . . . . . . . . 78
8.3. Packet Size . . . . . . . . . . . . . . . . . . . . . . . 80
8.4. Path Maximum Transmission Unit . . . . . . . . . . . . . 80
8.4.1. IPv4 PMTU Discovery . . . . . . . . . . . . . . . . . 81
8.4.2. Special Considerations for Packetization Layer PMTU 8.4.2. Special Considerations for Packetization Layer PMTU
Discovery . . . . . . . . . . . . . . . . . . . . . . 71 Discovery . . . . . . . . . . . . . . . . . . . . . . 82
9. Streams: QUIC's Data Structuring Abstraction . . . . . . . . 72 9. Streams: QUIC's Data Structuring Abstraction . . . . . . . . 82
9.1. Stream Identifiers . . . . . . . . . . . . . . . . . . . 73 9.1. Stream Identifiers . . . . . . . . . . . . . . . . . . . 83
9.2. Stream States . . . . . . . . . . . . . . . . . . . . . . 74 9.2. Stream States . . . . . . . . . . . . . . . . . . . . . . 84
9.2.1. Send Stream States . . . . . . . . . . . . . . . . . 74 9.2.1. Send Stream States . . . . . . . . . . . . . . . . . 85
9.2.2. Receive Stream States . . . . . . . . . . . . . . . . 76 9.2.2. Receive Stream States . . . . . . . . . . . . . . . . 86
9.2.3. Permitted Frame Types . . . . . . . . . . . . . . . . 79 9.2.3. Permitted Frame Types . . . . . . . . . . . . . . . . 89
9.2.4. Bidirectional Stream States . . . . . . . . . . . . . 79 9.2.4. Bidirectional Stream States . . . . . . . . . . . . . 89
9.3. Solicited State Transitions . . . . . . . . . . . . . . . 80 9.3. Solicited State Transitions . . . . . . . . . . . . . . . 90
9.4. Stream Concurrency . . . . . . . . . . . . . . . . . . . 81 9.4. Stream Concurrency . . . . . . . . . . . . . . . . . . . 91
9.5. Sending and Receiving Data . . . . . . . . . . . . . . . 82 9.5. Sending and Receiving Data . . . . . . . . . . . . . . . 92
9.6. Stream Prioritization . . . . . . . . . . . . . . . . . . 82 9.6. Stream Prioritization . . . . . . . . . . . . . . . . . . 92
10. Flow Control . . . . . . . . . . . . . . . . . . . . . . . . 83 10. Flow Control . . . . . . . . . . . . . . . . . . . . . . . . 93
10.1. Edge Cases and Other Considerations . . . . . . . . . . 85 10.1. Edge Cases and Other Considerations . . . . . . . . . . 94
10.1.1. Response to a RST_STREAM . . . . . . . . . . . . . . 85 10.1.1. Response to a RST_STREAM . . . . . . . . . . . . . . 95
10.1.2. Data Limit Increments . . . . . . . . . . . . . . . 85 10.1.2. Data Limit Increments . . . . . . . . . . . . . . . 95
10.1.3. Handshake Exemption . . . . . . . . . . . . . . . . 86 10.2. Stream Limit Increment . . . . . . . . . . . . . . . . . 96
10.2. Stream Limit Increment . . . . . . . . . . . . . . . . . 86 10.2.1. Blocking on Flow Control . . . . . . . . . . . . . . 96
10.2.1. Blocking on Flow Control . . . . . . . . . . . . . . 86 10.3. Stream Final Offset . . . . . . . . . . . . . . . . . . 96
10.3. Stream Final Offset . . . . . . . . . . . . . . . . . . 87 10.4. Flow Control for Crytographic Handshake . . . . . . . . 97
11. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 87 11. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 97
11.1. Connection Errors . . . . . . . . . . . . . . . . . . . 88 11.1. Connection Errors . . . . . . . . . . . . . . . . . . . 97
11.2. Stream Errors . . . . . . . . . . . . . . . . . . . . . 89 11.2. Stream Errors . . . . . . . . . . . . . . . . . . . . . 98
11.3. Transport Error Codes . . . . . . . . . . . . . . . . . 89 11.3. Transport Error Codes . . . . . . . . . . . . . . . . . 98
11.4. Application Protocol Error Codes . . . . . . . . . . . . 90 11.4. Application Protocol Error Codes . . . . . . . . . . . . 100
12. Security Considerations . . . . . . . . . . . . . . . . . . . 91 12. Security Considerations . . . . . . . . . . . . . . . . . . . 100
12.1. Spoofed ACK Attack . . . . . . . . . . . . . . . . . . . 91 12.1. Handshake Denial of Service . . . . . . . . . . . . . . 100
12.2. Optimistic ACK Attack . . . . . . . . . . . . . . . . . 91 12.2. Spoofed ACK Attack . . . . . . . . . . . . . . . . . . . 101
12.3. Slowloris Attacks . . . . . . . . . . . . . . . . . . . 92 12.3. Optimistic ACK Attack . . . . . . . . . . . . . . . . . 102
12.4. Stream Fragmentation and Reassembly Attacks . . . . . . 92 12.4. Slowloris Attacks . . . . . . . . . . . . . . . . . . . 102
12.5. Stream Commitment Attack . . . . . . . . . . . . . . . . 92 12.5. Stream Fragmentation and Reassembly Attacks . . . . . . 102
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 93 12.6. Stream Commitment Attack . . . . . . . . . . . . . . . . 103
13.1. QUIC Transport Parameter Registry . . . . . . . . . . . 93 12.7. Explicit Congestion Notification Attacks . . . . . . . . 103
13.2. QUIC Transport Error Codes Registry . . . . . . . . . . 94 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 103
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 96 13.1. QUIC Transport Parameter Registry . . . . . . . . . . . 104
14.1. Normative References . . . . . . . . . . . . . . . . . . 96 13.2. QUIC Frame Type Registry . . . . . . . . . . . . . . . . 105
14.2. Informative References . . . . . . . . . . . . . . . . . 97 13.3. QUIC Transport Error Codes Registry . . . . . . . . . . 106
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 98 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 108
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 98 14.1. Normative References . . . . . . . . . . . . . . . . . . 108
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 99 14.2. Informative References . . . . . . . . . . . . . . . . . 109
C.1. Since draft-ietf-quic-transport-11 . . . . . . . . . . . 99 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 110
C.2. Since draft-ietf-quic-transport-10 . . . . . . . . . . . 99 A.1. Since draft-ietf-quic-transport-12 . . . . . . . . . . . 110
C.3. Since draft-ietf-quic-transport-09 . . . . . . . . . . . 100 A.2. Since draft-ietf-quic-transport-11 . . . . . . . . . . . 111
C.4. Since draft-ietf-quic-transport-08 . . . . . . . . . . . 100 A.3. Since draft-ietf-quic-transport-10 . . . . . . . . . . . 111
C.5. Since draft-ietf-quic-transport-07 . . . . . . . . . . . 101 A.4. Since draft-ietf-quic-transport-09 . . . . . . . . . . . 112
C.6. Since draft-ietf-quic-transport-06 . . . . . . . . . . . 102 A.5. Since draft-ietf-quic-transport-08 . . . . . . . . . . . 113
C.7. Since draft-ietf-quic-transport-05 . . . . . . . . . . . 102 A.6. Since draft-ietf-quic-transport-07 . . . . . . . . . . . 113
C.8. Since draft-ietf-quic-transport-04 . . . . . . . . . . . 102 A.7. Since draft-ietf-quic-transport-06 . . . . . . . . . . . 114
C.9. Since draft-ietf-quic-transport-03 . . . . . . . . . . . 103 A.8. Since draft-ietf-quic-transport-05 . . . . . . . . . . . 115
C.10. Since draft-ietf-quic-transport-02 . . . . . . . . . . . 103 A.9. Since draft-ietf-quic-transport-04 . . . . . . . . . . . 115
C.11. Since draft-ietf-quic-transport-01 . . . . . . . . . . . 104 A.10. Since draft-ietf-quic-transport-03 . . . . . . . . . . . 116
C.12. Since draft-ietf-quic-transport-00 . . . . . . . . . . . 106 A.11. Since draft-ietf-quic-transport-02 . . . . . . . . . . . 116
C.13. Since draft-hamilton-quic-transport-protocol-01 . . . . . 106 A.12. Since draft-ietf-quic-transport-01 . . . . . . . . . . . 117
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 107 A.13. Since draft-ietf-quic-transport-00 . . . . . . . . . . . 119
A.14. Since draft-hamilton-quic-transport-protocol-01 . . . . . 119
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 119
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 120
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 secure transport for multiple it to be a general-purpose secure transport for multiple
applications. applications.
o Version negotiation o Version negotiation
skipping to change at page 8, line 36 skipping to change at page 9, line 17
|1| Type (7) | |1| Type (7) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version (32) | | Version (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|DCIL(4)|SCIL(4)| |DCIL(4)|SCIL(4)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Connection ID (0/32..144) ... | Destination Connection ID (0/32..144) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Connection ID (0/32..144) ... | Source Connection ID (0/32..144) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload Length (i) ... | Length (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packet Number (8/16/32) | | Packet Number (8/16/32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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.
skipping to change at page 9, line 16 skipping to change at page 9, line 45
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.
Version: The QUIC Version is a 32-bit field that follows the Type. Version: The QUIC Version is a 32-bit field that follows the Type.
This field indicates which version of QUIC is in use and This field indicates which version of QUIC is in use and
determines how the rest of the protocol fields are interpreted. determines how the rest of the protocol fields are interpreted.
DCIL and SCIL: Octet 1 contains the lengths of the two connection ID DCIL and SCIL: The octet following the version contains the lengths
fields that follow it. These lengths are encoded as two 4-bit of the two connection ID fields that follow it. These lengths are
unsigned integers. The Destination Connection ID Length (DCIL) encoded as two 4-bit unsigned integers. The Destination
field occupies the 4 high bits of the octet and the Source Connection ID Length (DCIL) field occupies the 4 high bits of the
Connection ID Length (SCIL) field occupies the 4 low bits of the octet and the Source Connection ID Length (SCIL) field occupies
octet. An encoded length of 0 indicates that the connection ID is the 4 low bits of the octet. An encoded length of 0 indicates
also 0 octets in length. Non-zero encoded lengths are increased that the connection ID is also 0 octets in length. Non-zero
by 3 to get the full length of the connection ID, producing a encoded lengths are increased by 3 to get the full length of the
length between 4 and 18 octets inclusive. For example, an octet connection ID, producing a length between 4 and 18 octets
with the value 0x50 describes an 8-octet Destination Connection ID inclusive. For example, an octet with the value 0x50 describes an
and a zero-length Source Connection ID. 8-octet Destination Connection ID and a zero-length Source
Connection ID.
Destination Connection ID: The Destination Connection ID field Destination Connection ID: The Destination Connection ID field
follows the connection ID lengths and is either 0 octets in length 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 or between 4 and 18 octets. Section 4.7 describes the use of this
field in more detail. field in more detail.
Source Connection ID: The Source Connection ID field follows the Source Connection ID: The Source Connection ID field follows the
Destination Connection ID and is either 0 octets in length or Destination Connection ID and is either 0 octets in length or
between 4 and 18 octets. Section 4.7 describes the use of this between 4 and 18 octets. Section 4.7 describes the use of this
field in more detail. field in more detail.
Payload Length: The length of the Payload field in octets, encoded Length: The length of the remainder of the packet (that is, the
as a variable-length integer (Section 7.1). Packet Number and Payload fields) in octets, encoded as a
variable-length integer (Section 7.1).
Packet Number: The packet number field is 1, 2, or 4 octets long. Packet Number: The packet number field is 1, 2, or 4 octets long.
The packet number has confidentiality protection separate from The packet number has confidentiality protection separate from
packet protection, as described in Section 5.6 of [QUIC-TLS]. The packet protection, as described in Section 5.6 of [QUIC-TLS]. The
length of the packet number field is encoded in the plaintext length of the packet number field is encoded in the plaintext
packet number. See Section 4.8 for details. packet number. See Section 4.8 for details.
Payload: The payload of the packet. Payload: The payload of the packet.
The following packet types are defined: The following packet types are defined:
skipping to change at page 10, line 30 skipping to change at page 11, line 11
source connection IDs, and version fields of a long header packet are source connection IDs, and version fields of a long header packet are
version-independent. The packet number and values for packet types version-independent. The packet number and values for packet types
defined in Table 1 are version-specific. See [QUIC-INVARIANTS] for defined in Table 1 are version-specific. See [QUIC-INVARIANTS] for
details on how packets from different versions of QUIC are details on how packets from different versions of QUIC are
interpreted. 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.
The end of the Payload field (which is also the end of the long The end of the packet is determined by the Length field. The Length
header packet) is determined by the value of the Payload Length field covers the both the Packet Number and Payload fields, both of
field. Senders can sometimes coalesce multiple packets into one UDP which are confidentiality protected and initially of unknown length.
The size of the Payload field is learned once the packet number
protection is removed.
Senders can sometimes coalesce multiple packets into one UDP
datagram. See Section 4.6 for more details. datagram. See Section 4.6 for more details.
4.2. Short Header 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|K|1|1|0|R R R| |0|K|1|1|0|R R R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Connection ID (0..144) ... | Destination Connection ID (0..144) ...
skipping to change at page 11, line 39 skipping to change at page 12, line 26
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.
Reserved: The sixth, seventh, and eighth bits (0x7) of octet 0 are Reserved: The sixth, seventh, and eighth bits (0x7) of octet 0 are
reserved for experimentation. reserved for experimentation.
Destination Connection ID: The Destination Connection ID is a Destination Connection ID: The Destination Connection ID is a
connection ID that is chosen by the intended recipient of the connection ID that is chosen by the intended recipient of the
packet. See Section 4.7 for more details. packet. See Section 6.1 for more details.
Packet Number: The packet number field is 1, 2, or 4 octets long. Packet Number: The packet number field is 1, 2, or 4 octets long.
The packet number has confidentiality protection separate from The packet number has confidentiality protection separate from
packet protection, as described in Section 5.6 of [QUIC-TLS]. The packet protection, as described in Section 5.6 of [QUIC-TLS]. The
length of the packet number field is encoded in the plaintext length of the packet number field is encoded in the plaintext
packet number. See Section 4.8 for details. packet number. See Section 4.8 for details.
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
of the packet number field. Additional types can be used to signal
the presence of other fields.
The header form and connection ID field of a short header packet are The header form and connection ID field of a short header packet are
version-independent. The remaining fields are specific to the version-independent. The remaining fields are specific to the
selected QUIC version. See [QUIC-INVARIANTS] for details on how selected QUIC version. See [QUIC-INVARIANTS] for details on how
packets from different versions of QUIC are interpreted. packets from different versions of QUIC are interpreted.
4.3. 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 long packet header (see Section 4.1. Upon receipt does not use the long packet header (see Section 4.1. Upon receipt
by a client, it will appear to be a packet using the long header, but by a client, it will appear to be a packet using the long header, but
skipping to change at page 13, line 26 skipping to change at page 14, line 10
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.
The Version Negotiation packet does not include the Packet Number and The Version Negotiation packet does not include the Packet Number and
Length fields present in other packets that use the long header form. Length fields present in other packets that use the long header form.
Consequently, a Version Negotiation packet consumes an entire UDP Consequently, a Version Negotiation packet consumes an entire UDP
datagram. datagram.
See Section 6.2 for a description of the version negotiation process. See Section 6.3 for a description of the version negotiation process.
4.4. Cryptographic Handshake Packets 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 4.4.1), Retry (Section 4.4.2) and carried in Initial (Section 4.4.1) and Handshake (Section 4.4.3)
Handshake (Section 4.4.3) packets. 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, Initial
handshake packets are protected with a connection- and version- packets are protected with connection- and version-specific keys
specific key, as described in [QUIC-TLS]. This protection does not (Initial keys) 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.
4.4.1. 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 CRYPTO frames sent by the client and server to
perform key exchange, and may carry ACKs in either direction. The
Initial packet is protected by Initial keys as described in
[QUIC-TLS].
If the client has not previously received a Retry packet from the The Initial packet has two additional header fields that follow the
server, it populates the Destination Connection ID field with a normal Long Header.
randomly selected value. This MUST be at least 8 octets in length.
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.
If the client received a Retry packet and is sending a second Initial 0 1 2 3
packet, then it sets the Destination Connection ID to the value from 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
the Source Connection ID in the Retry packet. Changing Destination +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Connection ID also results in a change to the keys used to protect | Token Length (i) ...
the Initial packet. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Token (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Token Length: A variable-length integer specifying the length of the
Token field, in bytes. It may be zero if no token is present.
Initial packets sent by the server MUST include a zero-length
token.
Token: An optional token blob previously received in either a Retry
packet or NEW_TOKEN frame.
The client and server use the Initial packet type for any packet that
contains an initial cryptographic handshake message. In addition to
the first packet(s). This includes all cases where a new packet
containing the initial cryptographic message needs to be created,
such as the packets sent after receiving a Version Negotiation
(Section 4.3) or Retry packet (Section 4.4.2).
A server sends its first Initial packet in response to a client
Initial. A server may send multiple Initial packets. The
cryptographic key exchange could require multiple round trips or
retransmissions of this data.
The payload of an Initial packet includes a CRYPTO frame (or frames)
containing a cryptographic handshake message, ACK frames, or both.
The first CRYPTO frame sent always begins at an offset of 0 (see
Section 6.4). The client's complete first message MUST fit in a
single packet (see Section 6.4). Note that if the server sends a
HelloRetryRequest, the client will send a second Initial packet with
a CRYPTO frame with an offset starting at the end of the CRYPTO
stream in the first Initial.
4.4.1.1. Connection IDs
When an Initial packet is sent by a client which has not previously
received a Retry packet from the server, it populates the Destination
Connection ID field with an unpredictable value. This MUST be at
least 8 octets in length. Until a packet is received from the
server, the client MUST use the same value unless it abandons the
connection attempt and starts a new one. The initial Destination
Connection ID is used to determine packet protection keys for Initial
packets.
The client populates the Source Connection ID field with a value of The client populates the Source Connection ID field with a value of
its choosing and sets the SCIL field to match. its choosing and sets the SCIL field to match.
The first Initial packet that is sent by a client contains a packet The Destination Connection ID field in the server's Initial packet
number of 0. All subsequent packets contain a packet number that is contains a connection ID that is chosen by the recipient of the
incremented by at least one, see (Section 4.8). packet (i.e., the client); the Source Connection ID includes the
connection ID that the sender of the packet wishes to use (see
Section 6.1). The server MUST use consistent Source Connection IDs
during the handshake.
The payload of an Initial packet conveys a STREAM frame (or frames) On first receiving an Initial or Retry packet from the server, the
for stream 0 containing a cryptographic handshake message. The client uses the Source Connection ID supplied by the server as the
stream in this packet always starts at an offset of 0 (see Destination Connection ID for subsequent packets. Once a client has
Section 6.5) and the complete cryptographic handshake message MUST received an Initial packet from the server, it MUST discard any
fit in a single packet (see Section 6.3). packet it receives with a different Source Connection ID.
4.4.1.2. Tokens
If the client has a suitable token available from a previous
connection, it SHOULD populate the Token field.
If the client received a Retry packet from the server and sends an
Initial packet in response, 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. It also sets the Token
field to the token provided in the Retry. The client MUST NOT change
the Source Connection ID because the server could include the
connection ID as part of its token validation logic.
When a server receives an Initial packet with an address validation
token, it SHOULD attempt to validate it. If the token is invalid
then the server SHOULD proceed as if the client did not have a
validated address, including potentially sending a Retry. If the
validation succeeds, the server SHOULD then allow the handshake to
proceed (see Section 6.7).
Note: The rationale for treating the client as unvalidated rather
than discarding the packet is that the client might have received
the token in a previous connection using the NEW_TOKEN frame, and
if the server has lost state, it might be unable to validate the
token at all, leading to connection failure if the packet is
discarded.
4.4.1.3. Starting Packet Numbers
The first Initial packet contains a packet number of 0. Each packet
sent after the Initial packet is associated with a packet number
space and its packet number increases monotonically in that space
(see Section 4.8).
4.4.1.4. Minimum Packet Size
The payload of a UDP datagram carrying the Initial packet MUST be The payload of a UDP datagram carrying the Initial packet MUST be
expanded to at least 1200 octets (see Section 8), by adding PADDING expanded to at least 1200 octets (see Section 8), by adding PADDING
frames to the Initial packet and/or by combining the Initial packet frames to the Initial packet and/or by combining the Initial packet
with a 0-RTT packet (see Section 4.6). with a 0-RTT packet (see Section 4.6).
The client uses the Initial packet type for any packet that contains
an initial cryptographic handshake message. This includes all cases
where a new packet containing the initial cryptographic message needs
to be created, this includes the packets sent after receiving a
Version Negotiation (Section 4.3) or Retry packet (Section 4.4.2).
4.4.2. 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 an address validation token created by the server. 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 6.5). Section 6.7).
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ODCIL(8 | Original Destination Connection ID (*) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Retry Token (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A Retry packet is not encrypted at all. Instead, the payload of a
Retry packet contains two values in the clear.
ODCIL: The length of the Original Destination Connection ID.
Original Destination Connection ID: The Destination Connection ID
from the Initial packet that this Retry is in response to. The
length of this field is given in DCIL.
Retry Token: An opaque token that the server can use to validate the
client's address.
The server populates the Destination Connection ID with the The server populates the Destination Connection ID with the
connection ID that the client included in the Source Connection ID of connection ID that the client included in the Source Connection ID of
the Initial packet. This might be a zero-length value. the Initial packet. This might be a zero-length value.
The server includes a connection ID of its choice in the Source The server includes a connection ID of its choice in the Source
Connection ID field. The client MUST use this connection ID in the Connection ID field. The client MUST use this connection ID in the
Destination Connection ID of subsequent packets that it sends. Destination Connection ID of subsequent packets that it sends.
The Packet Number field of a Retry packet MUST be set to 0. This The Packet Number field of a Retry packet MUST be set to 0. This
value is subsequently protected as normal. [[Editor's Note: This value is subsequently protected as normal. [[Editor's Note: This
isn't ideal, because it creates a "cheat" where the client assumes a isn't ideal, because it creates a "cheat" where the client assumes a
value. That's a problem, so I'm tempted to suggest that this include value. That's a problem, so I'm tempted to suggest that this include
any value less than 2^30 so that normal processing works - and can be any value less than 2^30 so that normal processing works - and can be
properly exercised.]] properly exercised.]]
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.
Retry packet.
After receiving a Retry packet, the client uses a new Initial packet A server MUST only send a Retry in response to a client Initial
containing the next cryptographic handshake message. The client packet.
retains the state of its cryptographic handshake, but discards all
transport state. The Initial packet that is generated in response to
a Retry packet includes STREAM frames on stream 0 that start again at
an offset of 0.
Continuing the cryptographic handshake is necessary to ensure that an If the Original Destination Connection ID field does not match the
attacker cannot force a downgrade of any cryptographic parameters. Destination Connection ID from most recent the Initial packet it
In addition to continuing the cryptographic handshake, the client sent, clients MUST discard the packet. This prevents an off-path
MUST remember the results of any version negotiation that occurred attacker from injecting a Retry packet with a bogus new Source
(see Section 6.2). The client MAY also retain any observed RTT or Connection ID.
congestion state that it has accumulated for the flow, but other
transport state MUST be discarded.
The payload of the Retry packet contains at least two frames. It Otherwise, the client SHOULD respond with a new Initial packet with
MUST include a STREAM frame on stream 0 with offset 0 containing the the Token field set to the token received in the Retry packet.
server's cryptographic stateless retry material. It MUST also
include an ACK frame to acknowledge the client's Initial packet. It
MAY additionally include PADDING frames. The next STREAM frame sent
by the server will also start at stream offset 0.
4.4.3. 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.
A server sends its cryptographic handshake in one or more Handshake A server sends its cryptographic handshake in one or more Handshake
packets in response to an Initial packet if it does not send a Retry packets in response to an Initial packet if it does not send a Retry
packet. Once a client has received a Handshake packet from a server, packet. Once a client has received a Handshake packet from a server,
it uses Handshake packets to send subsequent cryptographic handshake it uses Handshake packets to send subsequent cryptographic handshake
messages and acknowledgments to the server. messages and acknowledgments to the server.
The Destination Connection ID field in a Handshake packet contains a The Destination Connection ID field in a Handshake packet contains a
connection ID that is chosen by the recipient of the packet; the connection ID that is chosen by the recipient of the packet; the
Source Connection ID includes the connection ID that the sender of Source Connection ID includes the connection ID that the sender of
the packet wishes to use (see Section 4.7). the packet wishes to use (see Section 4.7).
The first Handshake packet sent by a server contains a packet number The first Handshake packet sent by a server contains a packet number
of 0. Packet numbers are incremented normally for other Handshake of 0. Handshake packets are their own packet number space. Packet
packets. numbers are incremented normally for other Handshake packets.
Servers MUST NOT send more than three Handshake packets without
receiving a packet from a verified source address. Source addresses
can be verified through an address validation token, receipt of the
final cryptographic message from the client, or by receiving a valid
PATH_RESPONSE frame from the client.
If the server expects to generate more than three Handshake packets Servers MUST NOT send more than three datagrams including Initial and
in response to an Initial packet, it SHOULD include a PATH_CHALLENGE Handshake packets without receiving a packet from a verified source
frame in each Handshake packet that it sends. After receiving at address. Source addresses can be verified through an address
least one valid PATH_RESPONSE frame, the server can send its validation token (delivered via a Retry packet or a NEW_TOKEN frame)
remaining Handshake packets. Servers can instead perform address or by receiving any message from the client encrypted using the
validation using a Retry packet; this requires less state on the Handshake keys.
server, but could involve additional computational effort depending
on implementation choices.
The payload of this packet contains STREAM frames and could contain The payload of this packet contains CRYPTO frames and could contain
PADDING, ACK, PATH_CHALLENGE, or PATH_RESPONSE frames. Handshake PADDING, or ACK frames. Handshake packets MAY contain
packets MAY contain CONNECTION_CLOSE frames if the handshake is CONNECTION_CLOSE frames if the handshake is unsuccessful.
unsuccessful.
4.5. Protected Packets 4.5. Protected Packets
All QUIC packets are protected. Packets that are protected with the All QUIC packets use packet protection. Packets that are protected
static handshake keys or the 0-RTT keys are sent with long headers; with the static handshake keys or the 0-RTT keys are sent with long
all packets protected with 1-RTT keys are sent with short headers. headers; all packets protected with 1-RTT keys are sent with short
The different packet types explicitly indicate the encryption level headers. The different packet types explicitly indicate the
and therefore the keys that are used to remove packet protection. encryption level and therefore the keys that are used to remove
packet protection. 0-RTT and 1-RTT protected packets share a single
packet number space.
Packets protected with handshake keys only use packet protection to
ensure that the sender of the packet is on the network path. This
packet protection is not effective confidentiality protection; any
entity that receives the Initial packet from a client can recover the
keys necessary to remove packet protection or to generate packets
that will be successfully authenticated.
Packets protected with 0-RTT and 1-RTT keys are expected to have
confidentiality and data origin authentication; the cryptographic
handshake ensures that only the communicating endpoints receive the
corresponding keys.
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 fields for a 0-RTT packet MUST match the values used in connection ID fields for a 0-RTT packet MUST match the values used in
the Initial packet (Section 4.4.1). 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 an Initial
(Section 4.4.3), if that packet does not complete the handshake. Section 4.4.1 or Handshake (Section 4.4.3) packet, if that packet
Even if the client receives a different connection ID in the does not complete the handshake. Even if the client receives a
Handshake packet, it MUST continue to use the same Destination different connection ID in the Handshake packet, it MUST continue to
Connection ID for 0-RTT packets, see Section 4.7. use the same Destination 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 has The packet number field contains a packet number, which has
additional confidentiality protection that is applied after packet additional confidentiality protection that is applied after packet
protection is applied (see [QUIC-TLS] for details). The underlying protection is applied (see [QUIC-TLS] for details). The underlying
packet number increases with each packet sent, see Section 4.8 for packet number increases with each packet sent, see Section 4.8 for
details. 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 5. Section 5.
4.6. Coalescing Packets 4.6. Coalescing Packets
A sender can coalesce multiple QUIC packets (typically a A sender can coalesce multiple QUIC packets (typically a
Cryptographic Handshake packet and a Protected packet) into one UDP Cryptographic Handshake packet and a Protected packet) into one UDP
datagram. This can reduce the number of UDP datagrams needed to send datagram. This can reduce the number of UDP datagrams needed to send
application data during the handshake and immediately afterwards. A application data during the handshake and immediately afterwards. It
packet with a short header does not include a length, so it has to be is not necessary for senders to coalesce packets, though failing to
the last packet included in a UDP datagram. do so will require sending a significantly larger number of datagrams
during the handshake. Receivers MUST be able to process coalesced
packets.
The sender MUST NOT coalesce QUIC packets belonging to different QUIC Senders SHOULD coalesce packets in order of increasing encryption
connections into a single UDP datagram. levels (Initial, Handshake, 0-RTT, 1-RTT), as this makes it more
likely the receiver will be able to process all the packets in a
single pass. A packet with a short header does not include a length,
so it will always be the last packet included in a UDP datagram.
Senders MUST NOT coalesce QUIC packets with different Destination
Connection IDs into a single UDP datagram. Receivers SHOULD ignore
any subsequent packets with a different Destination Connection ID
than the first packet in the datagram.
Every QUIC packet that is coalesced into a single UDP datagram is Every QUIC packet that is coalesced into a single UDP datagram is
separate and complete. Though the values of some fields in the separate and complete. Though the values of some fields in the
packet header might be redundant, no fields are omitted. The packet header might be redundant, no fields are omitted. The
receiver of coalesced QUIC packets MUST individually process each receiver of coalesced QUIC packets MUST individually process each
QUIC packet and separately acknowledge them, as if they were received QUIC packet and separately acknowledge them, as if they were received
as the payload of different UDP datagrams. as the payload of different UDP datagrams. If one or more packets in
a datagram cannot be processed yet (because the keys are not yet
available) or processing fails (decryption failure, unknown type,
etc.), the receiver MUST still attempt to process the remaining
packets. The skipped packets MAY either be discarded or buffered for
later processing, just as if the packets were received out-of-order
in separate datagrams.
4.7. Connection ID 4.7. Connection ID Encoding
A connection ID is used to ensure consistent routing of packets. The A connection ID is used to ensure consistent routing of packets, as
long header contains two connection IDs: the Destination Connection described in Section 6.1. The long header contains two connection
ID is chosen by the recipient of the packet and is used to provide IDs: the Destination Connection ID is chosen by the recipient of the
consistent routing; the Source Connection ID is used to set the packet and is used to provide consistent routing; the Source
Destination Connection ID used by the peer. Connection ID is used to set the Destination Connection ID used by
the peer.
During the handshake, packets with the long header are used to During the handshake, packets with the long header are used to
establish the connection ID that each endpoint uses. Each endpoint establish the connection ID that each endpoint uses. Each endpoint
uses the Source Connection ID field to specify the connection ID that uses the Source Connection ID field to specify the connection ID that
is used in the Destination Connection ID field of packets being sent is used in the Destination Connection ID field of packets being sent
to them. Upon receiving a packet, each endpoint sets the Destination to them. Upon receiving a packet, each endpoint sets the Destination
Connection ID it sends to match the value of the Source Connection ID Connection ID it sends to match the value of the Source Connection ID
that they receive. that they receive.
During the handshake, an endpoint might receive multiple packets with During the handshake, an endpoint might receive multiple packets with
the long header, and thus be given multiple opportunities to update the long header, and thus be given multiple opportunities to update
the Destination Connection ID it sends. A client MUST only change the Destination Connection ID it sends. A client MUST only change
the value it sends in the Destination Connection ID in response to 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 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. Initial); a server MUST set its value based on the Initial packet.
Any additional changes are not permitted; if subsequent packets of Any additional changes are not permitted; if subsequent packets of
those types include a different Source Connection ID, they MUST be those types include a different Source Connection ID, they MUST be
discarded. This avoids problems that might arise from stateless discarded. This avoids problems that might arise from stateless
processing of multiple Initial packets producing different connection processing of multiple Initial packets producing different connection
IDs. IDs.
Short headers only include the Destination Connection ID and omit the Short headers only include the Destination Connection ID and omit the
explicit length. The length of the Destination Connection ID field explicit length. The length of the Destination Connection ID field
is expected to be known to endpoints. is expected to be known to endpoints.
skipping to change at page 18, line 35 skipping to change at page 21, line 33
Destination Connection ID. The same value MUST be used for all 0-RTT Destination Connection ID. The same value MUST be used for all 0-RTT
packets sent on that connection (Section 4.5). This randomized value packets sent on that connection (Section 4.5). This randomized value
is used to determine the handshake packet protection keys (see is used to determine the handshake packet protection keys (see
Section 5.3.2 of [QUIC-TLS]). Section 5.3.2 of [QUIC-TLS]).
A Version Negotiation (Section 4.3) packet MUST use both connection A Version Negotiation (Section 4.3) packet MUST use both connection
IDs selected by the client, swapped to ensure correct routing toward IDs selected by the client, swapped to ensure correct routing toward
the client. the client.
The connection ID can change over the lifetime of a connection, The connection ID can change over the lifetime of a connection,
especially in response to connection migration (Section 6.8). especially in response to connection migration (Section 6.11).
NEW_CONNECTION_ID frames (Section 7.13) are used to provide new NEW_CONNECTION_ID frames (Section 7.13) are used to provide new
connection ID values. connection ID values.
4.8. Packet Numbers 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 start at zero for the receiving.
first packet sent and MUST increase by at least one after sending a
packet.
A QUIC endpoint MUST NOT reuse a packet number within the same Packet numbers are divided into 3 spaces in QUIC:
connection (that is, under the same cryptographic keys). If the
packet number for sending reaches 2^62 - 1, the sender MUST close the o Initial space: All Initial packets Section 4.4.1 are in this
connection without sending a CONNECTION_CLOSE frame or any further space.
packets; a server MAY send a Stateless Reset (Section 6.10.4) in
response to further packets that it receives. o Handshake space: All Handshake packets Section 4.4.3 are in this
space.
o Application data space: All 0-RTT and 1-RTT encrypted packets
Section 4.5 are in this space.
As described in [QUIC-TLS], each packet type uses different
encryption keys.
Conceptually, a packet number space is the encryption context in
which a packet can be processed and ACKed. Initial packets can only
be sent with Initial encryption keys and ACKed in packets which are
also Initial packets. Similarly, Handshake packets can only be sent
and acknowledged in Handshake packets.
This enforces cryptographic separation between the data sent in the
different packet sequence number spaces. Each packet number space
starts at packet number 0. Subsequent packets sent in the same
packet number space MUST increase the packet number by at least one.
0-RTT and 1-RTT data exist in the same packet number space to make
loss recovery algorithms easier to implement between the two packet
types.
A QUIC endpoint MUST NOT reuse a packet number within the same packet
number space in one connection (that is, under the same cryptographic
keys). If the packet number for sending reaches 2^62 - 1, the sender
MUST close the connection without sending a CONNECTION_CLOSE frame or
any further packets; an endpoint MAY send a Stateless Reset
(Section 6.13.4) in response to further packets that it receives.
In the QUIC long and short packet headers, the number of bits In the QUIC long and short packet headers, the number of bits
required to represent the packet number are reduced by including only required to represent the packet number are reduced by including only
a variable number of the least significant bits of the packet number. a variable number of the least significant bits of the packet number.
One or two of the most significant bits of the first octet determine One or two of the most significant bits of the first octet determine
how many bits of the packet number are provided, as shown in Table 2. how many bits of the packet number are provided, as shown in Table 2.
+---------------------+----------------+--------------+ +---------------------+----------------+--------------+
| First octet pattern | Encoded Length | Bits Present | | First octet pattern | Encoded Length | Bits Present |
+---------------------+----------------+--------------+ +---------------------+----------------+--------------+
skipping to change at page 19, line 41 skipping to change at page 23, line 18
reconstructed at the receiver based on the number of significant bits reconstructed at the receiver based on the number of significant bits
present, the content of those bits, and the largest packet number present, the content of those bits, and the largest packet number
received on a successfully authenticated packet. Recovering the full received on a successfully authenticated packet. Recovering the full
packet number is necessary to successfully remove packet protection. packet number is necessary to successfully remove packet protection.
Once packet number protection is removed, the packet number is Once packet number protection is removed, the packet number is
decoded by finding the packet number value that is closest to the decoded by finding the packet number value that is closest to the
next expected packet. The next expected packet is the highest next expected packet. The next expected packet is the highest
received packet number plus one. For example, if the highest received packet number plus one. For example, if the highest
successfully authenticated packet had a packet number of 0xaa82f30e, successfully authenticated packet had a packet number of 0xaa82f30e,
then a packet containing a 14-bit value of 0x1f94 will be decoded as then a packet containing a 14-bit value of 0x9b3 will be decoded as
0xaa831f94. 0xaa8309b3.
The sender MUST use a packet number size able to represent more than The sender MUST use a packet number size able to represent more than
twice as large a range than the difference between the largest twice as large a range than the difference between the largest
acknowledged packet and packet number being sent. A peer receiving acknowledged packet and packet number being sent. A peer receiving
the packet will then correctly decode the packet number, unless the the packet will then correctly decode the packet number, unless the
packet is delayed in transit such that it arrives after many higher- packet is delayed in transit such that it arrives after many higher-
numbered packets have been received. An endpoint SHOULD use a large numbered packets have been received. An endpoint SHOULD use a large
enough packet number encoding to allow the packet number to be enough packet number encoding to allow the packet number to be
recovered even if the packet arrives after packets that are sent recovered even if the packet arrives after packets that are sent
afterwards. afterwards.
skipping to change at page 20, line 45 skipping to change at page 24, line 23
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame N (*) ... | Frame N (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Contents of Protected Payload Figure 4: Contents of Protected Payload
Protected payloads MUST contain at least one frame, and MAY contain Protected payloads MUST contain at least one frame, and MAY contain
multiple frames and multiple frame types. multiple frames and multiple frame types.
Frames MUST fit within a single QUIC packet and MUST NOT span a QUIC Frames MUST fit within a single QUIC packet and MUST NOT span a QUIC
packet boundary. Each frame begins with a Frame Type byte, packet boundary. Each frame begins with a Frame Type, indicating its
indicating its type, followed by additional type-dependent fields: type, followed by additional type-dependent fields:
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 (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 The frame types defined in this specification are listed in Table 3.
STREAM frames is used to carry other frame-specific flags. For all The Frame Type in STREAM frames is used to carry other frame-specific
other frames, the Frame Type byte simply identifies the frame. These flags. For all other frames, the Frame Type field simply identifies
frames are explained in more detail as they are referenced later in the frame. These frames are explained in more detail as they are
the document. referenced later in the document.
+-------------+-------------------+--------------+ +-------------+-------------------+--------------+
| Type Value | Frame Type Name | Definition | | Type Value | Frame Type Name | Definition |
+-------------+-------------------+--------------+ +-------------+-------------------+--------------+
| 0x00 | PADDING | Section 7.2 | | 0x00 | PADDING | Section 7.2 |
| | | | | | | |
| 0x01 | RST_STREAM | Section 7.3 | | 0x01 | RST_STREAM | Section 7.3 |
| | | | | | | |
| 0x02 | CONNECTION_CLOSE | Section 7.4 | | 0x02 | CONNECTION_CLOSE | Section 7.4 |
| | | | | | | |
skipping to change at page 22, line 36 skipping to change at page 25, line 36
| 0x09 | STREAM_BLOCKED | Section 7.11 | | 0x09 | STREAM_BLOCKED | Section 7.11 |
| | | | | | | |
| 0x0a | STREAM_ID_BLOCKED | Section 7.12 | | 0x0a | STREAM_ID_BLOCKED | Section 7.12 |
| | | | | | | |
| 0x0b | NEW_CONNECTION_ID | Section 7.13 | | 0x0b | NEW_CONNECTION_ID | Section 7.13 |
| | | | | | | |
| 0x0c | STOP_SENDING | Section 7.14 | | 0x0c | STOP_SENDING | Section 7.14 |
| | | | | | | |
| 0x0d | ACK | Section 7.15 | | 0x0d | ACK | Section 7.15 |
| | | | | | | |
| 0x0e | PATH_CHALLENGE | Section 7.16 | | 0x0e | PATH_CHALLENGE | Section 7.17 |
| | | | | | | |
| 0x0f | PATH_RESPONSE | Section 7.17 | | 0x0f | PATH_RESPONSE | Section 7.18 |
| | | | | | | |
| 0x10 - 0x17 | STREAM | Section 7.18 | | 0x10 - 0x17 | STREAM | Section 7.20 |
| | | |
| 0x18 | CRYPTO | Section 7.21 |
| | | |
| 0x19 | NEW_TOKEN | Section 7.19 |
| | | |
| 0x20 | ACK_ECN | Section 7.16 |
+-------------+-------------------+--------------+ +-------------+-------------------+--------------+
Table 3: Frame Types Table 3: Frame Types
All QUIC frames are idempotent. That is, a valid frame does not
cause undesirable side effects or errors when received more than
once.
The Frame Type field uses a variable length integer encoding (see
Section 7.1) with one exception. To ensure simple and efficient
implementations of frame parsing, a frame type MUST use the shortest
possible encoding. Though a two-, four- or eight-octet encoding of
the frame types defined in this document is possible, the Frame Type
field for these frames are encoded on a single octet. For instance,
though 0x4007 is a legitimate two-octet encoding for a variable-
length integer with a value of 7, PING frames are always encoded as a
single octet with the value 0x07. An endpoint MUST treat the receipt
of a frame type that uses a longer encoding than necessary as a
connection error of type PROTOCOL_VIOLATION.
5.1. Extension Frames
QUIC frames do not use a self-describing encoding. An endpoint
therefore needs to understand the syntax of all frames before it can
successfully process a packet. This allows for efficient encoding of
frames, but it means that an endpoint cannot send a frame of a type
that is unknown to its peer.
An extension to QUIC that wishes to use a new type of frame MUST
first ensure that a peer is able to understand the frame. An
endpoint can use a transport parameter to signal its willingness to
receive one or more extension frame types with the one transport
parameter.
An IANA registry is used to manage the assignment of frame types, see
Section 13.2.
6. 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 6.3. Once connection establishment latency, as described in Section 6.4. 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 6.8. Finally a connection may be terminated by either Section 6.11. Finally a connection may be terminated by either
endpoint, as described in Section 6.10. endpoint, as described in Section 6.13.
6.1. Matching Packets to Connections 6.1. Connection ID
Each connection is identified by a collection of identifiers assigned
to it. A connection ID can be 0 octets in length (and thus unlikely
to be unique), or between 4 and 18 octets (inclusive). Connection
IDs are selected independently in each direction.
The primary function of a connection ID is to ensure that changes in
addressing at lower protocol layers (UDP, IP, and below) don't cause
packets for a QUIC connection to be delivered to the wrong endpoint.
Each endpoint selects connection IDs using an implementation-specific
(and perhaps deployment-specific) method which will allow packets
with that connection ID to be routed back to the endpoint and
identified by the endpoint upon receipt.
A zero-length connection ID MAY be used when the connection ID is not
needed for routing and the address/port tuple of packets is
sufficient to associate them to a connection. An endpoint whose peer
has selected a zero-length connection ID MUST continue to use a zero-
length connection ID for the lifetime of the connection and MUST NOT
send packets from any other local address.
When an endpoint has requested a non-zero-length connection ID, it
will issue a series of connection IDs over the lifetime of a
connection. The series of connection IDs issued by an endpoint is
ordered, with the final connection ID selected during the handshake
coming first. Additional connection IDs are provided using the
NEW_CONNECTION_ID frame (Section 7.13), each with a specified
sequence number. The series of connection IDs issued SHOULD be
contiguous, but might not appear to be upon receipt due to reordering
or loss.
Each connection ID MUST be used on only one local address. When
packets are sent for the first time on a new local address, a new
connection ID MUST be used with a higher sequence number than any
connection ID previously used on any local address. At any time, an
endpoint MAY change to a new connection ID on a local address already
in use.
An endpoint MUST NOT send packets with a connection ID which has a
lower sequence number than the highest sequence number of any
connection ID ever sent or received on that local address. This
ensures that when an endpoint migrates to a new path or changes
connection ID on an existing path, the packets will use a new
connection ID in both directions.
Implementations SHOULD ensure that peers have a connection ID with a
matching sequence number available when changing to a new connection
ID. An implementation could do this by always supplying a
corresponding connection ID to a peer for each connection ID received
from that peer.
While endpoints select connection IDs as appropriate for their
implementation, the connection ID MUST NOT include the unprotected
sequence number. Endpoints need to be able to recover the sequence
number associated with each connection ID they generate without
relying on information available to unaffiliate parties. A
connection ID that encodes an unencrypted sequence number could be
used to correlate connection IDs across network paths.
6.2. 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 a packet with an existing connection. If the Hosts try to associate a packet with an existing connection. If the
packet has a Destination 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 more
NEW_CONNECTION_ID frame (Section 7.13) would associate more than one than one connection ID can be associated with a connection; see
connection ID with a connection. Section 6.1.
If the Destination Connection ID is zero length and the packet If the Destination Connection ID is zero length and the packet
matches the address/port tuple of a connection where the host did not matches the address/port tuple of a connection where the host did not
require connection IDs, QUIC processes the packet as part of that require connection IDs, QUIC processes the packet as part of that
connection. Endpoints MUST drop packets with zero-length Destination connection. Endpoints MUST drop packets with zero-length Destination
Connection ID fields if they do not correspond to a single Connection ID fields if they do not correspond to a single
connection. connection.
6.1.1. Client Packet Handling 6.2.1. Client Packet Handling
Valid packets sent to clients always include a Destination Connection Valid packets sent to clients always include a Destination Connection
ID that matches the value the client selects. Clients that choose to ID that matches the value the client selects. Clients that choose to
receive zero-length connection IDs can use the address/port tuple to receive zero-length connection IDs can use the address/port tuple to
identify a connection. Packets that don't match an existing identify a connection. Packets that don't match an existing
connection MAY be discarded. 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 that are encrypted with a key it has not yet computed. connection that are encrypted with a key it has not yet computed.
Clients MAY drop these packets, or MAY buffer them in anticipation of Clients MAY drop these packets, or MAY buffer them in anticipation of
later packets that allow it to compute the key. later packets that allow it to compute the key.
If a client receives a packet that has an unsupported version, it If a client receives a packet that has an unsupported version, it
MUST discard that packet. MUST discard that packet.
6.1.2. Server Packet Handling 6.2.2. 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 6.2.1. Servers MAY rate control these packets described in Section 6.3.1. 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 The first packet for an unsupported version can use different
semantics and encodings for any version-specific field. In semantics and encodings for any version-specific field. In
particular, different packet protection keys might be used for particular, different packet protection keys might be used for
different versions. Servers that do not support a particular version different versions. Servers that do not support a particular version
are unlikely to be able to decrypt the content of the packet. are unlikely to be able to decrypt the content of the packet.
Servers SHOULD NOT attempt to decode or decrypt a packet from an Servers SHOULD NOT attempt to decode or decrypt a packet from an
unknown version, but instead send a Version Negotiation packet, unknown version, but instead send a Version Negotiation packet,
provided that the packet is sufficiently long. 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 6.1. If not matched, the server a connection as described in Section 6.2. 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 6.3). specification, the server proceeds with the handshake (Section 6.4).
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 6.10.4) if a connection They SHOULD send a Stateless Reset (Section 6.13.4) if a connection
ID is present in the header. ID is present in the header.
6.2. Version Negotiation 6.3. 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 6.1 for details. new connection, see Section 6.2 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 the server responds if there are any mutually supported
supported versions. versions.
6.2.1. Sending Version Negotiation Packets 6.3.1. 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 (see server, the server responds with a Version Negotiation packet (see
Section 4.3). 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.
6.2.2. Handling Version Negotiation Packets 6.3.2. 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 Destination and Source Connection ID fields match the checks that the Destination and Source Connection ID fields match the
Source and Destination Connection ID fields in a packet that the Source and Destination Connection ID fields in a packet that the
client sent. If this check fails, the packet MUST be discarded. 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 Initial connection using that version. Though the contents of the Initial
skipping to change at page 25, line 51 skipping to change at page 31, line 10
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 6.4.4). cryptographic handshake (see Section 6.6.4).
6.2.3. Using Reserved Versions 6.3.3. 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 3) 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 6.4.4) only validates validation of version negotiation (see Section 6.6.4) 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.
6.3. Cryptographic and Transport Handshake 6.4. 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 uses the CRYPTO
for the cryptographic handshake. Version 0x00000001 of QUIC uses TLS frame Section 7.21 to transmit the cryptographic handshake. Version
1.3 as described in [QUIC-TLS]; a different QUIC version number could 0x00000001 of QUIC uses TLS 1.3 as described in [QUIC-TLS]; a
indicate that a different cryptographic handshake protocol is in use. different QUIC version number could indicate that a different
cryptographic handshake protocol is in use.
QUIC provides this stream with reliable, ordered delivery of data. QUIC provides reliable, ordered delivery of the cryptographic
In return, the cryptographic handshake provides QUIC with: handshake data. QUIC packet protection ensures confidentiality and
integrity protection that meets the requirements of the cryptographic
handshake protocol:
o authenticated key exchange, where o authenticated key exchange, where
* a server is always authenticated, * a server is always authenticated,
* 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 6.4) Section 6.6)
o authenticated confirmation of version negotiation (see o authenticated confirmation of version negotiation (see
Section 6.4.4) Section 6.6.4)
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 6.6) transport address that is claimed by the client (see Section 6.9)
The initial cryptographic handshake message MUST be sent in a single The initial CRYPTO frame MUST be sent in a single packet. Any second
packet. Any second attempt that is triggered by address validation attempt that is triggered by address validation MUST also be sent
MUST also be sent within a single packet. This avoids having to within a single packet. This avoids having to reassemble a message
reassemble a message from multiple packets. Reassembling messages from multiple packets.
requires that a server maintain state prior to establishing a
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 The CRYPTO frame can be sent in different packet number spaces.
in [QUIC-TLS]. CRYPTO frames in each packet number space carry a separate sequence
of handshake data starting from an offset of 0.
6.4. Transport Parameters 6.5. Example Handshake Flows
Details of how TLS is integrated with QUIC are provided in
[QUIC-TLS], but some examples are provided here.
Figure 6 provides an overview of the 1-RTT handshake. Each line
shows a QUIC packet with the packet type and packet number shown
first, followed by the contents. So, for instance the first packet
is of type Initial, with packet number 0, and contains a CRYPTO frame
carrying the ClientHello.
Note that multiple QUIC packets - even of different encryption levels
- may be coalesced into a single UDP datagram (see Section 4.6, and
so this handshake may consist of as few as 4 UDP datagrams, or any
number more. For instance, the server's first flight contains
packets from the Initial encryption level (obfuscation), the
Handshake level, and "0.5-RTT data" from the server at the 1-RTT
encryption level.
Client Server
Initial[0]: CRYPTO[CH] ->
Initial[0]: CRYPTO[SH] ACK[0]
Handshake[0]: CRYPTO[EE, CERT, CV, FIN]
<- 1-RTT[0]: STREAM[1, "..."]
Initial[1]: ACK[0]
Handshake[0]: CRYPTO[FIN], ACK[0]
1-RTT[0]: STREAM[0, "..."], ACK[0] ->
1-RTT[1]: STREAM[55, "..."], ACK[0]
<- Handshake[1]: ACK[0]
Figure 6: Example 1-RTT Handshake
Figure 7 shows an example of a connection with a 0-RTT handshake and
a single packet of 0-RTT data. Note that as described in
Section 4.8, the server ACKs the 0-RTT data at the 1-RTT encryption
level, and the client's sequence numbers at the 1-RTT encryption
level continue to increment from its 0-RTT packets.
Client Server
Initial[0]: CRYPTO[CH]
0-RTT[0]: STREAM[0, "..."] ->
Initial[0]: CRYPTO[SH] ACK[0]
Handshake[0] CRYPTO[EE, CERT, CV, FIN]
<- 1-RTT[0]: STREAM[1, "..."] ACK[0]
Initial[1]: ACK[0]
0-RTT[1]: CRYPTO[EOED]
Handshake[0]: CRYPTO[FIN], ACK[0]
1-RTT[2]: STREAM[0, "..."] ACK[0] ->
1-RTT[1]: STREAM[55, "..."], ACK[1,2]
<- Handshake[1]: ACK[0]
Figure 7: Example 1-RTT Handshake
6.6. 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 8. 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_bidi_streams(2), initial_max_bidi_streams(2),
idle_timeout(3), idle_timeout(3),
preferred_address(4), preferred_address(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_uni_streams(8), initial_max_uni_streams(8),
disable_migration(9),
(65535) (65535)
} TransportParameterId; } TransportParameterId;
struct { struct {
TransportParameterId parameter; TransportParameterId parameter;
opaque value<0..2^16-1>; opaque value<0..2^16-1>;
} TransportParameter; } TransportParameter;
struct { struct {
select (Handshake.msg_type) { select (Handshake.msg_type) {
skipping to change at page 28, line 45 skipping to change at page 35, line 46
} TransportParameters; } TransportParameters;
struct { struct {
enum { IPv4(4), IPv6(6), (15) } ipVersion; enum { IPv4(4), IPv6(6), (15) } ipVersion;
opaque ipAddress<4..2^8-1>; opaque ipAddress<4..2^8-1>;
uint16 port; uint16 port;
opaque connectionId<0..18>; opaque connectionId<0..18>;
opaque statelessResetToken[16]; opaque statelessResetToken[16];
} PreferredAddress; } PreferredAddress;
Figure 6: Definition of TransportParameters Figure 8: Definition of TransportParameters
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 6.4.4) before the connection establishment is considered Section 6.6.4) 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 6.4.1. Any given parameter MUST appear at most once in a in Section 6.6.1. 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.
6.4.1. Transport Parameter Definitions 6.6.1. 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 7.7) 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.
skipping to change at page 29, line 46 skipping to change at page 36, line 49
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).
An endpoint MAY use the following transport parameters: An endpoint MAY use the following transport parameters:
initial_max_bidi_streams (0x0002): The initial maximum bidirectional initial_max_bidi_streams (0x0002): The initial maximum bidirectional
streams parameter contains the initial maximum number of streams parameter contains the initial maximum number of
application-owned bidirectional streams the peer may initiate, application-owned bidirectional streams the peer may initiate,
encoded as an unsigned 16-bit integer. If this parameter is encoded as an unsigned 16-bit integer. If this parameter is
absent or zero, application-owned bidirectional streams cannot be absent or zero, application-owned bidirectional streams cannot be
created until a MAX_STREAM_ID frame is sent. Note that a value of created until a MAX_STREAM_ID frame is sent. Setting this
0 does not prevent the cryptographic handshake stream (that is, parameter is equivalent to sending a MAX_STREAM_ID (Section 7.8)
stream 0) from being used. Setting this parameter is equivalent immediately after completing the handshake containing the
to sending a MAX_STREAM_ID (Section 7.8) immediately after corresponding Stream ID. For example, a value of 0x05 would be
completing the handshake containing the corresponding Stream ID. equivalent to receiving a MAX_STREAM_ID containing 16 when
For example, a value of 0x05 would be equivalent to receiving a received by a client or 17 when received by a server.
MAX_STREAM_ID containing 20 when received by a client or 17 when
received by a server.
initial_max_uni_streams (0x0008): The initial maximum unidirectional initial_max_uni_streams (0x0008): The initial maximum unidirectional
streams parameter contains the initial maximum number of streams parameter contains the initial maximum number of
application-owned unidirectional streams the peer may initiate, application-owned unidirectional streams the peer may initiate,
encoded as an unsigned 16-bit integer. If this parameter is encoded as an unsigned 16-bit integer. If this parameter is
absent or zero, unidirectional streams cannot be created until a absent or zero, unidirectional streams cannot be created until a
MAX_STREAM_ID frame is sent. Setting this parameter is equivalent MAX_STREAM_ID frame is sent. Setting this parameter is equivalent
to sending a MAX_STREAM_ID (Section 7.8) immediately after to sending a MAX_STREAM_ID (Section 7.8) immediately after
completing the handshake containing the corresponding Stream ID. completing the handshake containing the corresponding Stream ID.
For example, a value of 0x05 would be equivalent to receiving a For example, a value of 0x05 would be equivalent to receiving a
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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 4.5). 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 7.15. 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 and
Handshake, and Retry packets. Values above 20 are invalid. Handshake packets. Values above 20 are invalid.
disable_migration (0x0009): The endpoint does not support connection
migration (Section 6.11). Peers MUST NOT send any packets,
including probing packets (Section 6.11.1), from a local address
other than that used to perform the handshake. This parameter is
a zero-length value.
A server MAY include the following transport parameters: A server MAY include the following transport parameters:
stateless_reset_token (0x0006): The Stateless Reset Token is used in stateless_reset_token (0x0006): The Stateless Reset Token is used in
verifying a stateless reset, see Section 6.10.4. This parameter verifying a stateless reset, see Section 6.13.4. This parameter
is a sequence of 16 octets. is a sequence of 16 octets.
preferred_address (0x0004): The server's Preferred Address is used preferred_address (0x0004): The server's Preferred Address is used
to effect a change in server address at the end of the handshake, to effect a change in server address at the end of the handshake,
as described in Section 6.9. as described in Section 6.12.
A client MUST NOT include a stateless reset token or a preferred A client MUST NOT include a stateless reset token or a preferred
address. A server MUST treat receipt of either transport parameter address. A server MUST treat receipt of either transport parameter
as a connection error of type TRANSPORT_PARAMETER_ERROR. as a connection error of type TRANSPORT_PARAMETER_ERROR.
6.4.2. Values of Transport Parameters for 0-RTT 6.6.2. 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
skipping to change at page 31, line 43 skipping to change at page 38, line 47
initial_max_bidi_streams, initial_max_uni_streams, initial_max_data, initial_max_bidi_streams, initial_max_uni_streams, initial_max_data,
initial_max_stream_data. initial_max_stream_data.
The value of the server's previous preferred_address MUST NOT be used The value of the server's previous preferred_address MUST NOT be used
when establishing a new connection; rather, the client should wait to when establishing a new connection; rather, the client should wait to
observe the server's new preferred_address value in the handshake. observe the server's new preferred_address value in the handshake.
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.
6.4.3. New Transport Parameters 6.6.3. 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 13.1. Section 13.1.
6.4.4. Version Negotiation Validation 6.6.4. 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 6.2). retroactively authenticate the choice of version (see Section 6.3).
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 6.4). As a result, attacks on version negotiation by an Section 6.6). 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 4.3, 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
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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.
6.5. Stateless Retries 6.7. 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 6.6), or to defer connection perform address validation (Section 6.9), 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 4.4.2). 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 restart the connection attempt and
continue the connection attempt with new connection state while includes the token in the new Initial packet (Section 4.4.1) to prove
maintaining the state of the cryptographic handshake. source address ownership.
A server MUST NOT send multiple Retry packets in response to a client 6.8. Using Explicit Congestion Notification
handshake packet. Thus, any cryptographic handshake message that is
sent MUST fit within a single packet.
In TLS, the Retry packet type is used to carry the HelloRetryRequest QUIC endpoints use Explicit Congestion Notification (ECN) [RFC3168]
message. to detect and respond to network congestion. ECN allows a network
node to indicate congestion in the network by setting a codepoint in
the IP header of a packet instead of dropping it. Endpoints react to
congestion by reducing their sending rate in response, as described
in [QUIC-RECOVERY].
6.6. Proof of Source Address Ownership To use ECN, QUIC endpoints first determine whether a path and peer
support ECN marking. Verifying the path occurs at the beginning of a
connection and when the connection migrates to a new path (see
Section 6.11).
Each endpoint independently verifies and enables ECN for the path
from it to the peer.
To verify that both a path and the peer support ECN, an endpoint MUST
set one of the ECN Capable Transport (ECT) codepoints - ECT(0) or
ECT(1) - in the IP header [RFC8311] of all outgoing packets.
If an ECT codepoint set in the IP header is not corrupted by a
network device, then a received packet contains either the codepoint
sent by the peer or the Congestion Experienced (CE) codepoint set by
a network device that is experiencing congestion.
On receiving a packet with an ECT or CE codepoint, an endpoint that
supports ECN increases the corresponding ECT(0), ECT(1), or CE count,
and includes these counters in subsequent (see Section 8.1) ACK_ECN
frames (see Section 7.16).
A packet detected by a receiver as a duplicate does not affect the
receiver's local ECN codepoint counts to mitigate security concerns
(Section 12.7).
If an endpoint receives a packet without an ECT or CE codepoint, it
responds per Section 8.1 with an ACK frame.
If an endpoint does not support ECN or does not have access to
received ECN codepoints, it acknowledges received packets per
Section 8.1 with an ACK frame.
If a packet sent with an ECT codepoint is newly acknowledged by the
peer in an ACK frame, the endpoint stops setting ECT codepoints in
subsequent packets, with the expectation that either the network or
the peer no longer supports ECN.
To protect the connection from arbitrary corruption of ECN codepoints
by the network, an endpoint verifies the following when an ACK_ECN
frame is received:
o The total increase in ECT(0), ECT(1), and CE counters reported in
the ACK_ECN frame MUST be equal to the total number of packets
newly acknowledged in this ACK_ECN frame.
o The increase in ECT(0) and ECT(1) counters MUST be no greater than
the number of packets newly acknowledged that were sent with the
corresponding codepoint.
Upon successful verification, an endpoint continues to set ECT
codepoints in subsequent packets with the expectation that the path
is ECN-capable.
If verification fails, then the endpoint ceases setting ECT
codepoints in subsequent packets with the expectation that either the
network or the peer does not support ECN.
If an endpoint sets ECT codepoints on outgoing packets and encounters
a retransmission timeout due to the absence of acknowledgments from
the peer (see [QUIC-RECOVERY]), the endpoint MAY cease setting ECT
codepoints in subsequent packets. Doing so allows the connection to
traverse network elements that drop packets carrying ECT or CE
codepoints in the IP header.
6.9. 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
victim. If a server generates more or larger packets in response to victim. If a server generates more or larger packets in response to
that packet, the attacker can use the server to send more data toward that packet, the attacker can use the server to send more data toward
the victim than it would be able to send on its own. the victim than it would be able to send on its own.
Several methods are used in QUIC to mitigate this attack. Firstly, Several methods are used in QUIC to mitigate this attack. Firstly,
the initial handshake packet is padded to at least 1200 octets. This the initial handshake packet is padded to at least 1200 octets. This
allows a server to send a similar amount of data without risking allows a server to send a similar amount of data without risking
causing an amplification attack toward an unproven remote address. causing an amplification attack toward an unproven remote address.
A server eventually confirms that a client has received its messages A server eventually confirms that a client has received its messages
when the cryptographic handshake successfully completes. This might when the first Handshake-level message is received. This might be
be insufficient, either because the server wishes to avoid the insufficient, either because the server wishes to avoid the
computational cost of completing the handshake, or it might be that computational cost of completing the handshake, or it might be that
the size of the packets that are sent during the handshake is too the size of the packets that are sent during the handshake is too
large. This is especially important for 0-RTT, where the server large. This is especially important for 0-RTT, where the server
might wish to provide application data traffic - such as a response might wish to provide application data traffic - such as a response
to a request - in response to the data carried in the early data from to a request - in response to the data carried in the early data from
the client. the client.
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 by the core
establishment of a connection. TLS provides the tools that support transport protocol during the establishment of a connection.
the feature, but basic validation is performed by the core transport
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 6.7. connection migration, see Section 6.10.
6.6.1. Client Address Validation Procedure 6.9.1. 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 6.6.3), if As long as the token's authenticity can be checked (see
the client is able to return that token, it proves to the server that Section 6.9.3) and the client is able to return that token, it proves
it received the token. to the server that it received the token.
During the processing of the cryptographic handshake messages from a
client, TLS will request that QUIC make a decision about whether to
proceed based on the information it has. TLS will provide QUIC with
any token that was provided by the client. For an initial packet,
QUIC can decide to abort the connection, allow it to proceed, or
request address validation.
If QUIC decides to request address validation, it provides the Upon receiving the client's Initial packet, the server can request
cryptographic handshake with a token. The contents of this token are address validation by sending a Retry packet containing a token.
consumed by the server that generates the token, so there is no need This token is repeated in the client's next Initial packet. Because
for a single well-defined format. A token could include information the token is consumed by the server that generates it, there is no
about the claimed client address (IP and port), a timestamp, and any need for a single well-defined format. A token could include
other supplementary information the server will need to validate the information about the claimed client address (IP and port), a
token in the future. timestamp, and any other supplementary information the server will
need to validate the token in the future.
The cryptographic handshake is responsible for enacting validation by The Retry packet is sent to the client and a legitimate client will
sending the address validation token to the client. A legitimate respond with an Initial packet containing the token from the Retry
client will include a copy of the token when it attempts to continue packet when it continues the handshake. In response to receiving the
the handshake. The cryptographic handshake extracts the token then token, a server can either abort the connection or permit it to
asks QUIC a second time whether the token is acceptable. In
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.
6.6.2. Address Validation on Session Resumption The client should allow for additional Retry packets being sent in
response to Initial packets sent containing a token. There are
several situations in which the server might not be able to use the
previously generated token to validate the client's address and must
send a new Retry. A reasonable limit to the number of tries the
client allows for, before giving up, is 3. That is, the client MUST
echo the address validation token from a new Retry packet up to 3
times. After that, it MAY give up on the connection attempt.
6.9.2. Address Validation for Future Connections
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 The server uses the NEW_TOKEN frame Section 7.19 to provide the
that is created during a handshake, there might be some time between client with an address validation token that can be used to validate
when the token is created and when the token is subsequently used. future connections. The client may then use this token to validate
Thus, a resumption token SHOULD include an expiration time. It is future connections by including it in the Initial packet's header.
also unlikely that the client port number is the same on two The client MUST NOT use the token provided in a Retry for future
different connections; validating the port is therefore unlikely to connections.
be successful.
This token can be provided to the cryptographic handshake immediately Unlike the token that is created for a Retry packet, there might be
after establishing a connection. QUIC might also generate an updated some time between when the token is created and when the token is
token if significant time passes or the client address changes for subsequently used. Thus, a resumption token SHOULD include an
any reason (see Section 6.8). The cryptographic handshake is expiration time. The server MAY include either an explicit
responsible for providing the client with the token. In TLS the expiration time or an issued timestamp and dynamically calculate the
token is included in the ticket that is used for resumption and expiration time. It is also unlikely that the client port number is
0-RTT, which is carried in a NewSessionTicket message. the same on two different connections; validating the port is
therefore unlikely to be successful.
6.6.3. Address Validation Token Integrity 6.9.3. 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
tokens that would be accepted by the server. Only the server tokens that would be accepted by the server. Only the server
requires access to the integrity protection key for tokens. requires access to the integrity protection key for tokens.
In TLS the address validation token is often bundled with the 6.10. Path Validation
information that TLS requires, such as the resumption secret. In
this case, adding integrity protection can be delegated to the
cryptographic handshake protocol, avoiding redundant protection. If
integrity protection is delegated to the cryptographic handshake, an
integrity failure will result in immediate cryptographic handshake
failure. If integrity protection is performed by QUIC, QUIC MUST
abort the connection if the integrity check fails with a
PROTOCOL_VIOLATION error code.
6.7. Path Validation
Path validation is used by an endpoint to verify reachability of a Path validation is used by an endpoint to verify reachability of a
peer over a specific path. That is, it tests reachability between a peer over a specific path. That is, it tests reachability between a
specific local address and a specific peer address, where an address specific local address and a specific peer address, where an address
is the two-tuple of IP address and port. Path validation tests that is the two-tuple of IP address and port. Path validation tests that
packets can be both sent to and received from a peer. packets can be both sent to and received from a peer.
Path validation is used during connection migration (see Section 6.8 Path validation is used during connection migration (see Section 6.11
and Section 6.9) by the migrating endpoint to verify reachability of and Section 6.12) by the migrating endpoint to verify reachability of
a peer from a new local address. Path validation is also used by the a peer from a new local address. Path validation is also used by the
peer to verify that the migrating endpoint is able to receive packets peer to verify that the migrating endpoint is able to receive packets
sent to the its new address. That is, that the packets received from sent to the its new address. That is, that the packets received from
the migrating endpoint do not carry a spoofed source address. the migrating endpoint do not carry a spoofed source address.
Path validation can be used at any time by either endpoint. For Path validation can be used at any time by either endpoint. For
instance, an endpoint might check that a peer is still in possession instance, an endpoint might check that a peer is still in possession
of its address after a period of quiescence. of its address after a period of quiescence.
Path validation is not designed as a NAT traversal mechanism. Though Path validation is not designed as a NAT traversal mechanism. Though
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or other peer is able to receive packets without first having sent a or other peer is able to receive packets without first having sent a
packet on that path. Effective NAT traversal needs additional packet on that path. Effective NAT traversal needs additional
synchronization mechanisms that are not provided here. synchronization mechanisms that are not provided here.
An endpoint MAY bundle PATH_CHALLENGE and PATH_RESPONSE frames that An endpoint MAY bundle PATH_CHALLENGE and PATH_RESPONSE frames that
are used for path validation with other frames. For instance, an are used for path validation with other frames. For instance, an
endpoint may pad a packet carrying a PATH_CHALLENGE for PMTU endpoint may pad a packet carrying a PATH_CHALLENGE for PMTU
discovery, or an endpoint may bundle a PATH_RESPONSE with its own discovery, or an endpoint may bundle a PATH_RESPONSE with its own
PATH_CHALLENGE. PATH_CHALLENGE.
6.7.1. Initiation 6.10.1. Initiation
To initiate path validation, an endpoint sends a PATH_CHALLENGE frame To initiate path validation, an endpoint sends a PATH_CHALLENGE frame
containing a random payload on the path to be validated. containing a random payload on the path to be validated.
An endpoint MAY send additional PATH_CHALLENGE frames to handle An endpoint MAY send additional PATH_CHALLENGE frames to handle
packet loss. An endpoint SHOULD NOT send a PATH_CHALLENGE more packet loss. An endpoint SHOULD NOT send a PATH_CHALLENGE more
frequently than it would an Initial packet, ensuring that connection frequently than it would an Initial packet, ensuring that connection
migration is no more load on a new path than establishing a new migration is no more load on a new path than establishing a new
connection. connection.
The endpoint MUST use fresh random data in every PATH_CHALLENGE frame The endpoint MUST use fresh random data in every PATH_CHALLENGE frame
so that it can associate the peer's response with the causative so that it can associate the peer's response with the causative
PATH_CHALLENGE. PATH_CHALLENGE.
6.7.2. Response 6.10.2. Response
On receiving a PATH_CHALLENGE frame, an endpoint MUST respond On receiving a PATH_CHALLENGE frame, an endpoint MUST respond
immediately by echoing the data contained in the PATH_CHALLENGE frame immediately by echoing the data contained in the PATH_CHALLENGE frame
in a PATH_RESPONSE frame, with the following stipulation. Since a in a PATH_RESPONSE frame, with the following stipulation. Since a
PATH_CHALLENGE might be sent from a spoofed address, an endpoint MAY PATH_CHALLENGE might be sent from a spoofed address, an endpoint MAY
limit the rate at which it sends PATH_RESPONSE frames and MAY limit the rate at which it sends PATH_RESPONSE frames and MAY
silently discard PATH_CHALLENGE frames that would cause it to respond silently discard PATH_CHALLENGE frames that would cause it to respond
at a higher rate. at a higher rate.
To ensure that packets can be both sent to and received from the To ensure that packets can be both sent to and received from the
peer, the PATH_RESPONSE MUST be sent on the same path as the peer, the PATH_RESPONSE MUST be sent on the same path as the
triggering PATH_CHALLENGE: from the same local address on which the triggering PATH_CHALLENGE: from the same local address on which the
PATH_CHALLENGE was received, to the same remote address from which PATH_CHALLENGE was received, to the same remote address from which
the PATH_CHALLENGE was received. the PATH_CHALLENGE was received.
6.7.3. Completion 6.10.3. Completion
A new address is considered valid when a PATH_RESPONSE frame is A new address is considered valid when a PATH_RESPONSE frame is
received containing data that was sent in a previous PATH_CHALLENGE. received containing data that was sent in a previous PATH_CHALLENGE.
Receipt of an acknowledgment for a packet containing a PATH_CHALLENGE Receipt of an acknowledgment for a packet containing a PATH_CHALLENGE
frame is not adequate validation, since the acknowledgment can be frame is not adequate validation, since the acknowledgment can be
spoofed by a malicious peer. spoofed by a malicious peer.
For path validation to be successful, a PATH_RESPONSE frame MUST be For path validation to be successful, a PATH_RESPONSE frame MUST be
received from the same remote address to which the corresponding received from the same remote address to which the corresponding
PATH_CHALLENGE was sent. If a PATH_RESPONSE frame is received from a PATH_CHALLENGE was sent. If a PATH_RESPONSE frame is received from a
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Additionally, the PATH_RESPONSE frame MUST be received on the same Additionally, the PATH_RESPONSE frame MUST be received on the same
local address from which the corresponding PATH_CHALLENGE was sent. local address from which the corresponding PATH_CHALLENGE was sent.
If a PATH_RESPONSE frame is received on a different local address If a PATH_RESPONSE frame is received on a different local address
than the one from which the PATH_CHALLENGE was sent, path validation 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 is considered to have failed, even if the data matches that sent in
the PATH_CHALLENGE. Thus, the endpoint considers the path to be the PATH_CHALLENGE. Thus, the endpoint considers the path to be
valid when a PATH_RESPONSE frame is received on the same path with valid when a PATH_RESPONSE frame is received on the same path with
the same payload as the PATH_CHALLENGE frame. the same payload as the PATH_CHALLENGE frame.
6.7.4. Abandonment 6.10.4. Abandonment
An endpoint SHOULD abandon path validation after sending some number An endpoint SHOULD abandon path validation after sending some number
of PATH_CHALLENGE frames or after some time has passed. When setting of PATH_CHALLENGE frames or after some time has passed. When setting
this timer, implementations are cautioned that the new path could this timer, implementations are cautioned that the new path could
have a longer round-trip time than the original. have a longer round-trip time than the original.
Note that the endpoint might receive packets containing other frames Note that the endpoint might receive packets containing other frames
on the new path, but a PATH_RESPONSE frame with appropriate data is on the new path, but a PATH_RESPONSE frame with appropriate data is
required for path validation to succeed. required for path validation to succeed.
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necessarily imply a failure of the connection - endpoints can necessarily imply a failure of the connection - endpoints can
continue sending packets over other paths as appropriate. If no continue sending packets over other paths as appropriate. If no
paths are available, an endpoint can wait for a new path to become paths are available, an endpoint can wait for a new path to become
available or close the connection. available or close the connection.
A path validation might be abandoned for other reasons besides A path validation might be abandoned for other reasons besides
failure. Primarily, this happens if a connection migration to a new failure. Primarily, this happens if a connection migration to a new
path is initiated while a path validation on the old path is in path is initiated while a path validation on the old path is in
progress. progress.
6.8. Connection Migration 6.11. Connection Migration
QUIC allows connections to survive changes to endpoint addresses QUIC allows connections to survive changes to endpoint addresses
(that is, IP address and/or port), such as those caused by a endpoint (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 migrating to a new network. This section describes the process by
which an endpoint migrates to a new address. which an endpoint migrates to a new address.
An endpoint MUST NOT initiate connection migration before the An endpoint MUST NOT initiate connection migration before the
handshake is finished and the endpoint has 1-RTT keys. handshake is finished and the endpoint has 1-RTT keys. An endpoint
also MUST NOT initiate connection migration if the peer sent the
"disable_migration" transport parameter during the handshake. An
endpoint which has sent this transport parameter, but detects that a
peer has nonetheless migrated to a different network MAY treat this
as a connection error of type INVALID_MIGRATION. However, note that
not all changes of peer address are intentional migrations. The peer
could experience an unintended change of address due to NAT
rebinding; endpoints SHOULD perform path validation (Section 6.10) if
the rebinding does not cause the connection to fail.
This document limits migration of connections to new client This document limits migration of connections to new client
addresses, except as described in Section 6.9. Clients are addresses, except as described in Section 6.12. Clients are
responsible for initiating all migrations. Servers do not send non- responsible for initiating all migrations. Servers do not send non-
probing packets (see Section 6.8.1) toward a client address until it probing packets (see Section 6.11.1) toward a client address until it
sees a non-probing packet from that address. If a client receives sees a non-probing packet from that address. If a client receives
packets from an unknown server address, the client MAY discard these packets from an unknown server address, the client MAY discard these
packets. packets.
6.8.1. Probing a New Path 6.11.1. Probing a New Path
An endpoint MAY probe for peer reachability from a new local address An endpoint MAY probe for peer reachability from a new local address
using path validation Section 6.7 prior to migrating the connection using path validation Section 6.10 prior to migrating the connection
to the new local address. Failure of path validation simply means to the new local address. Failure of path validation simply means
that the new path is not usable for this connection. Failure to that the new path is not usable for this connection. Failure to
validate a path does not cause the connection to end unless there are validate a path does not cause the connection to end unless there are
no valid alternative paths available. no valid alternative paths available.
An endpoint uses a new connection ID for probes sent from a new local An endpoint uses a new connection ID for probes sent from a new local
address, see Section 6.8.5 for further discussion. address, see Section 6.11.5 for further discussion.
Receiving a PATH_CHALLENGE frame from a peer indicates that the peer Receiving a PATH_CHALLENGE frame from a peer indicates that the peer
is probing for reachability on a path. An endpoint sends a is probing for reachability on a path. An endpoint sends a
PATH_RESPONSE in response as per Section 6.7. PATH_RESPONSE in response as per Section 6.10.
PATH_CHALLENGE, PATH_RESPONSE, and PADDING frames are "probing PATH_CHALLENGE, PATH_RESPONSE, and PADDING frames are "probing
frames", and all other frames are "non-probing frames". A packet frames", and all other frames are "non-probing frames". A packet
containing only probing frames is a "probing packet", and a packet containing only probing frames is a "probing packet", and a packet
containing any other frame is a "non-probing packet". containing any other frame is a "non-probing packet".
6.8.2. Initiating Connection Migration 6.11.2. Initiating Connection Migration
A endpoint can migrate a connection to a new local address by sending A endpoint can migrate a connection to a new local address by sending
packets containing frames other than probing frames from that packets containing frames other than probing frames from that
address. address.
Each endpoint validates its peer's address during connection Each endpoint validates its peer's address during connection
establishment. Therefore, a migrating endpoint can send to its peer establishment. Therefore, a migrating endpoint can send to its peer
knowing that the peer is willing to receive at the peer's current knowing that the peer is willing to receive at the peer's current
address. Thus an endpoint can migrate to a new local address without address. Thus an endpoint can migrate to a new local address without
first validating the peer's address. first validating the peer's address.
When migrating, the new path might not support the endpoint's current When migrating, the new path might not support the endpoint's current
sending rate. Therefore, the endpoint resets its congestion sending rate. Therefore, the endpoint resets its congestion
controller, as described in Section 6.8.4. controller, as described in Section 6.11.4.
The new path might not have the same ECN capability. Therefore, the
endpoint verifies ECN capability as described in Section 6.8.
Receiving acknowledgments for data sent on the new path serves as Receiving acknowledgments for data sent on the new path serves as
proof of the peer's reachability from the new address. Note that proof of the peer's reachability from the new address. Note that
since acknowledgments may be received on any path, return since acknowledgments may be received on any path, return
reachability on the new path is not established. To establish return reachability on the new path is not established. To establish return
reachability on the new path, an endpoint MAY concurrently initiate reachability on the new path, an endpoint MAY concurrently initiate
path validation Section 6.7 on the new path. path validation Section 6.10 on the new path.
6.8.3. Responding to Connection Migration 6.11.3. Responding to Connection Migration
Receiving a packet from a new peer address containing a non-probing Receiving a packet from a new peer address containing a non-probing
frame indicates that the peer has migrated to that address. frame indicates that the peer has migrated to that address.
In response to such a packet, an endpoint MUST start sending In response to such a packet, an endpoint MUST start sending
subsequent packets to the new peer address and MUST initiate path subsequent packets to the new peer address and MUST initiate path
validation (Section 6.7) to verify the peer's ownership of the validation (Section 6.10) to verify the peer's ownership of the
unvalidated address. unvalidated address.
An endpoint MAY send data to an unvalidated peer address, but it MUST 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 protect against potential attacks as described in Section 6.11.3.1
Section 6.8.3.2. An endpoint MAY skip validation of a peer address and Section 6.11.3.2. An endpoint MAY skip validation of a peer
if that address has been seen recently. address if that address has been seen recently.
An endpoint only changes the address that it sends packets to in An endpoint only changes the address that it sends packets to in
response to the highest-numbered non-probing packet. This ensures response to the highest-numbered non-probing packet. This ensures
that an endpoint does not send packets to an old peer address in the that an endpoint does not send packets to an old peer address in the
case that it receives reordered packets. case that it receives reordered packets.
After changing the address to which it sends non-probing packets, an After changing the address to which it sends non-probing packets, an
endpoint could abandon any path validation for other addresses. endpoint could abandon any path validation for other addresses.
Receiving a packet from a new peer address might be the result of a Receiving a packet from a new peer address might be the result of a
NAT rebinding at the peer. NAT rebinding at the peer.
After verifying a new client address, the server SHOULD send new After verifying a new client address, the server SHOULD send new
address validation tokens (Section 6.6) to the client. address validation tokens (Section 6.9) to the client.
6.8.3.1. Handling Address Spoofing by a Peer 6.11.3.1. Handling Address Spoofing by a Peer
It is possible that a peer is spoofing its source address to cause an 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 endpoint to send excessive amounts of data to an unwilling host. If
the endpoint sends significantly more data than the spoofing peer, the endpoint sends significantly more data than the spoofing peer,
connection migration might be used to amplify the volume of data that connection migration might be used to amplify the volume of data that
an attacker can generate toward a victim. an attacker can generate toward a victim.
As described in Section 6.8.3, an endpoint is required to validate a As described in Section 6.11.3, an endpoint is required to validate a
peer's new address to confirm the peer's possession of the new 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 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 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 MUST NOT send more than a minimum congestion window's worth of data
per estimated round-trip time (kMinimumWindow, as defined in per estimated round-trip time (kMinimumWindow, as defined in
[QUIC-RECOVERY]). In the absence of this limit, an endpoint risks [QUIC-RECOVERY]). In the absence of this limit, an endpoint risks
being used for a denial of service attack against an unsuspecting being used for a denial of service attack against an unsuspecting
victim. Note that since the endpoint will not have any round-trip victim. Note that since the endpoint will not have any round-trip
time measurements to this address, the estimate SHOULD be the default time measurements to this address, the estimate SHOULD be the default
initial value (see [QUIC-RECOVERY]). initial value (see [QUIC-RECOVERY]).
If an endpoint skips validation of a peer address as described in 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. Section 6.11.3, it does not need to limit its sending rate.
6.8.3.2. Handling Address Spoofing by an On-path Attacker 6.11.3.2. Handling Address Spoofing by an On-path Attacker
An on-path attacker could cause a spurious connection migration by An on-path attacker could cause a spurious connection migration by
copying and forwarding a packet with a spoofed address such that it copying and forwarding a packet with a spoofed address such that it
arrives before the original packet. The packet with the spoofed arrives before the original packet. The packet with the spoofed
address will be seen to come from a migrating connection, and the address will be seen to come from a migrating connection, and the
original packet will be seen as a duplicate and dropped. After a original packet will be seen as a duplicate and dropped. After a
spurious migration, validation of the source address will fail spurious migration, validation of the source address will fail
because the entity at the source address does not have the necessary because the entity at the source address does not have the necessary
cryptographic keys to read or respond to the PATH_CHALLENGE frame cryptographic keys to read or respond to the PATH_CHALLENGE frame
that is sent to it even if it wanted to. that is sent to it even if it wanted to.
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MUST close the connection silently by discarding all connection MUST close the connection silently by discarding all connection
state. This results in new packets on the connection being handled state. This results in new packets on the connection being handled
generically. For instance, an endpoint MAY send a stateless reset in generically. For instance, an endpoint MAY send a stateless reset in
response to any further incoming packets. response to any further incoming packets.
Note that receipt of packets with higher packet numbers from the Note that receipt of packets with higher packet numbers from the
legitimate peer address will trigger another connection migration. legitimate peer address will trigger another connection migration.
This will cause the validation of the address of the spurious This will cause the validation of the address of the spurious
migration to be abandoned. migration to be abandoned.
6.8.4. Loss Detection and Congestion Control 6.11.4. Loss Detection and Congestion Control
The capacity available on the new path might not be the same as the 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 old path. Packets sent on the old path SHOULD NOT contribute to
congestion control or RTT estimation for the new path. congestion control or RTT estimation for the new path.
On confirming a peer's ownership of its new address, an endpoint On confirming a peer's ownership of its new address, an endpoint
SHOULD immediately reset the congestion controller and round-trip SHOULD immediately reset the congestion controller and round-trip
time estimator for the new path. time estimator for the new path.
An endpoint MUST NOT return to the send rate used for the previous An endpoint MUST NOT return to the send rate used for the previous
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single congestion control context and a single loss recovery context single congestion control context and a single loss recovery context
(as described in [QUIC-RECOVERY]) may be adequate. A sender can make (as described in [QUIC-RECOVERY]) may be adequate. A sender can make
exceptions for probe packets so that their loss detection is exceptions for probe packets so that their loss detection is
independent and does not unduly cause the congestion controller to independent and does not unduly cause the congestion controller to
reduce its sending rate. An endpoint might arm a separate alarm when reduce its sending rate. An endpoint might arm a separate alarm when
a PATH_CHALLENGE is sent, which is disarmed when the corresponding 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. If the alarm fires before the
PATH_RESPONSE is received, the endpoint might send a new PATH_RESPONSE is received, the endpoint might send a new
PATH_CHALLENGE, and restart the alarm for a longer period of time. PATH_CHALLENGE, and restart the alarm for a longer period of time.
6.8.5. Privacy Implications of Connection Migration 6.11.5. Privacy Implications of Connection Migration
Using a stable connection ID on multiple network paths allows a Using a stable connection ID on multiple network paths allows a
passive observer to correlate activity between those paths. An passive observer to correlate activity between those paths. An
endpoint that moves between networks might not wish to have their endpoint that moves between networks might not wish to have their
activity correlated by any entity other than their peer. The activity correlated by any entity other than their peer, so different
NEW_CONNECTION_ID message can be sent to provide an unlinkable connection IDs are used when sending from different local addresses,
connection ID for use in case a peer wishes to explicitly break as discussed in Section 6.1.
linkability between two points of network attachment.
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 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 is
needed for each network. To support this, multiple NEW_CONNECTION_ID
messages are needed. 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 to break linkability upon changing networks MUST use This eliminates the use of the connection ID for linking activity
a previously unused connection ID provided by its peer. Protection from the same connection on different networks. Protection of packet
of packet numbers ensures that packet numbers cannot be used to numbers ensures that packet numbers cannot be used to correlate
correlate connections. Other properties of packets, such as timing activity. This does not prevent other properties of packets, such as
and size, might be used to correlate activity, but no explicit timing and size, from being used to correlate activity.
correlation can be used to link activity across paths.
Clients MAY change connection ID at any time based on implementation- Clients MAY move to a new connection ID at any time based on
specific concerns. For example, after a period of network inactivity implementation-specific concerns. For example, after a period of
NAT rebinding might occur when the client begins sending data again. network inactivity NAT rebinding might occur when the client begins
sending data again.
A client might wish to reduce linkability by employing a new A client might wish to reduce linkability by employing a new
connection ID and source UDP port when sending traffic after a period connection ID and source UDP port when sending traffic after a period
of inactivity. Changing the UDP port from which it sends packets at of inactivity. Changing the UDP port from which it sends packets at
the same time might cause the packet to appear as a connection the same time might cause the packet to appear as a connection
migration. This ensures that the mechanisms that support migration migration. This ensures that the mechanisms that support migration
are exercised even for clients that don't experience NAT rebindings are exercised even for clients that don't experience NAT rebindings
or genuine migrations. Changing port number can cause a peer to or genuine migrations. Changing port number can cause a peer to
reset its congestion state (see Section 6.8.4), so the port SHOULD reset its congestion state (see Section 6.11.4), so the port SHOULD
only be changed infrequently. only be changed infrequently.
An endpoint that receives a successfully authenticated packet with a 6.12. Server's Preferred Address
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.
6.9. Server's Preferred Address
QUIC allows servers to accept connections on one IP address and QUIC allows servers to accept connections on one IP address and
attempt to transfer these connections to a more preferred address attempt to transfer these connections to a more preferred address
shortly after the handshake. This is particularly useful when shortly after the handshake. This is particularly useful when
clients initially connect to an address shared by multiple servers clients initially connect to an address shared by multiple servers
but would prefer to use a unicast address to ensure connection but would prefer to use a unicast address to ensure connection
stability. This section describes the protocol for migrating a stability. This section describes the protocol for migrating a
connection to a preferred server address. connection to a preferred server address.
Migrating a connection to a new server address mid-connection is left Migrating a connection to a new server address mid-connection is left
for future work. If a client receives packets from a new server for future work. If a client receives packets from a new server
address not indicated by the preferred_address transport parameter, address not indicated by the preferred_address transport parameter,
the client SHOULD discard these packets. the client SHOULD discard these packets.
6.9.1. Communicating A Preferred Address 6.12.1. Communicating A Preferred Address
A server conveys a preferred address by including the A server conveys a preferred address by including the
preferred_address transport parameter in the TLS handshake. preferred_address transport parameter in the TLS handshake.
Once the handshake is finished, the client SHOULD initiate path Once the handshake is finished, the client SHOULD initiate path
validation (see Section 6.7) of the server's preferred address using validation (see Section 6.10) of the server's preferred address using
the connection ID provided in the preferred_address transport the connection ID provided in the preferred_address transport
parameter. parameter.
If path validation succeeds, the client SHOULD immediately begin If path validation succeeds, the client SHOULD immediately begin
sending all future packets to the new server address using the new sending all future packets to the new server address using the new
connection ID and discontinue use of the old server address. If path connection ID and discontinue use of the old server address. If path
validation fails, the client MUST continue sending all future packets validation fails, the client MUST continue sending all future packets
to the server's original IP address. to the server's original IP address.
6.9.2. Responding to Connection Migration 6.12.2. Responding to Connection Migration
A server might receive a packet addressed to its preferred IP address A server might receive a packet addressed to its preferred IP address
at any time after the handshake is completed. If this packet at any time after the handshake is completed. If this packet
contains a PATH_CHALLENGE frame, the server sends a PATH_RESPONSE contains a PATH_CHALLENGE frame, the server sends a PATH_RESPONSE
frame as per Section 6.7, but the server MUST continue sending all frame as per Section 6.10, but the server MUST continue sending all
other packets from its original IP address. other packets from its original IP address.
The server SHOULD also initiate path validation of the client using The server SHOULD also initiate path validation of the client using
its preferred address and the address from which it received the its preferred address and the address from which it received the
client probe. This helps to guard against spurious migration client probe. This helps to guard against spurious migration
initiated by an attacker. initiated by an attacker.
Once the server has completed its path validation and has received a Once the server has completed its path validation and has received a
non-probing packet with a new largest packet number on its preferred non-probing packet with a new largest packet number on its preferred
address, the server begins sending to the client exclusively from its address, the server begins sending to the client exclusively from its
preferred IP address. It SHOULD drop packets for this connection preferred IP address. It SHOULD drop packets for this connection
received on the old IP address, but MAY continue to process delayed received on the old IP address, but MAY continue to process delayed
packets. packets.
6.9.3. Interaction of Client Migration and Preferred Address 6.12.3. Interaction of Client Migration and Preferred Address
A client might need to perform a connection migration before it has A client might need to perform a connection migration before it has
migrated to the server's preferred address. In this case, the client migrated to the server's preferred address. In this case, the client
SHOULD perform path validation to both the original and preferred SHOULD perform path validation to both the original and preferred
server address from the client's new address concurrently. server address from the client's new address concurrently.
If path validation of the server's preferred address succeeds, the If path validation of the server's preferred address succeeds, the
client MUST abandon validation of the original address and migrate to client MUST abandon validation of the original address and migrate to
using the server's preferred address. If path validation of the using the server's preferred address. If path validation of the
server's preferred address fails, but validation of the server's server's preferred address fails, but validation of the server's
original address succeeds, the client MAY migrate to using the original address succeeds, the client MAY migrate to using the
original address from the client's new address. original address from the client's new address.
If the connection to the server's preferred address is not from the If the connection to the server's preferred address is not from the
same client address, the server MUST protect against potential same client address, the server MUST protect against potential
attacks as described in Section 6.8.3.1 and Section 6.8.3.2. In attacks as described in Section 6.11.3.1 and Section 6.11.3.2. In
addition to intentional simultaneous migration, this might also occur addition to intentional simultaneous migration, this might also occur
because the client's access network used a different NAT binding for because the client's access network used a different NAT binding for
the server's preferred address. the server's preferred address.
Servers SHOULD initiate path validation to the client's new address Servers SHOULD initiate path validation to the client's new address
upon receiving a probe packet from a different address. Servers MUST upon receiving a probe packet from a different address. Servers MUST
NOT send more than a minimum congestion window's worth of non-probing NOT send more than a minimum congestion window's worth of non-probing
packets to the new address before path validation is complete. packets to the new address before path validation is complete.
6.10. Connection Termination 6.13. 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 6.10.2) o idle timeout (Section 6.13.2)
o immediate close (Section 6.10.3) o immediate close (Section 6.13.3)
o stateless reset (Section 6.10.4) o stateless reset (Section 6.13.4)
6.10.1. Closing and Draining Connection States 6.13.1. 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 6.10.3). While closing, an endpoint MUST NOT send close (Section 6.13.3). While closing, an endpoint MUST NOT send
packets unless they contain a CONNECTION_CLOSE or APPLICATION_CLOSE packets unless they contain a CONNECTION_CLOSE or APPLICATION_CLOSE
frame (see Section 6.10.3 for details). frame (see Section 6.13.3 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 46, line 47 skipping to change at page 54, line 33
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 6.10.4) is sent. (Section 6.13.4) 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 client connection migration (Section 6.8), while in the indicating a client connection migration (Section 6.11), while in the
closing period. An endpoint in the closing state MUST strictly limit closing period. An endpoint in the closing state MUST strictly limit
the number of packets it sends to this new address until the address the number of packets it sends to this new address until the address
is validated (see Section 6.7). A server in the closing state MAY is validated (see Section 6.10). A server in the closing state MAY
instead choose to discard packets received from a new source address. instead choose to discard packets received from a new source address.
6.10.2. Idle Timeout 6.13.2. 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 6.4.1) is closed. A connection enters the draining state Section 6.6.1) 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.
6.10.3. Immediate Close 6.13.3. Immediate Close
An endpoint sends a closing frame, either CONNECTION_CLOSE or An endpoint sends a closing frame (CONNECTION_CLOSE or
APPLICATION_CLOSE, to terminate the connection immediately. Either APPLICATION_CLOSE) to terminate the connection immediately. Any
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
that an endpoint maintains for a closing connection, endpoints MAY that an endpoint maintains for a closing connection, endpoints MAY
send the exact same packet. However, endpoints SHOULD limit the send the exact same packet. However, endpoints SHOULD limit the
number of packets they generate containing a closing frame. For number of packets they generate containing a closing frame. For
skipping to change at page 48, line 16 skipping to change at page 56, line 5
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.
6.10.4. Stateless Reset 6.13.4. 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 an
server that does not have access to the state of a connection. A endpoint that does not have access to the state of a connection. A
server crash or outage might result in clients continuing to send crash or outage might result in peers continuing to send data to an
data to a server that is unable to properly continue the connection. endpoint that is unable to properly continue the connection. An
A server that wishes to communicate a fatal connection error MUST use endpoint 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, a token is sent by endpoints. The token is
value during the handshake in the transport parameters. This value carried in the NEW_CONNECTION_ID frame sent by either peer, and
is protected by encryption, so only client and server know this servers can specify the stateless_reset_token transport parameter
value. during the handshake (clients cannot because their transport
parameters don't have confidentiality protection). This value is
protected by encryption, so only client and server know this value.
A server that receives packets that it cannot process sends a packet An endpoint that receives packets that it cannot process sends a
in the following layout: packet 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|K| Type (6) | |0|K|1|1|0|0|0|0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Connection ID (144) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packet Number (8/16/32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Random Octets (*) ... | Random Octets (160..) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ Stateless Reset Token (128) + + Stateless Reset Token (128) +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This design ensures that a stateless reset packet is - to the extent This design ensures that a stateless reset packet is - to the extent
possible - indistinguishable from a regular packet with a short possible - indistinguishable from a regular packet with a short
header. header.
A server generates a random 18-octet Destination Connection ID field. The message consists of a header octet, followed by random octets of
For a client that depends on the server including a connection ID, arbitrary length, followed by a Stateless Reset Token.
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 A stateless reset will be interpreted by a recipient as a packet with
Connection ID is critical for routing toward the client, then this a short header. For the packet to appear as valid, the Random Octets
field needs to include at least 20 octets of random or unpredictable
values. This is intended to allow for a destination connection ID of
the maximum length permitted, a packet number, and minimal payload.
The Stateless Reset Token corresponds to the minimum expansion of the
packet protection AEAD. More random octets might be necessary if the
endpoint could have negotiated a packet protection scheme with a
larger minimum AEAD expansion.
An endpoint SHOULD NOT send a stateless reset that is significantly
larger than the packet it receives. Endpoints MUST discard packets
that are too small to be valid QUIC packets. With the set of AEAD
functions defined in [QUIC-TLS], packets less than 19 octets long are
never valid.
An endpoint cannot determine the Source Connection ID from a packet
with a short header, therefore it cannot set the Destination
Connection ID in the stateless reset packet. The destination
connection ID will therefore differ from the value used in previous
packets. A random Destination Connection ID makes the connection ID
appear to be the result of moving to a new connection ID that was
provided using a NEW_CONNECTION_ID frame (Section 7.13).
Using a randomized connection ID results in two problems:
o The packet might not reach the peer. If the Destination
Connection ID is critical for routing toward the peer, then this
packet could be incorrectly routed. This causes the stateless packet could be incorrectly routed. This causes the stateless
reset to be ineffective in causing errors to be quickly detected reset to be ineffective in causing errors to be quickly detected
and recovered. In this case, clients will need to rely on other and recovered. In this case, endpoints will need to rely on other
methods - such as timers - to detect that the connection has methods - such as timers - to detect that the connection has
failed. failed.
o The randomly generated connection ID can be used by entities other o The randomly generated connection ID can be used by entities other
than the client to identify this as a potential stateless reset. than the peer to identify this as a potential stateless reset. An
A server that occasionally uses different connection IDs might endpoint that occasionally uses different connection IDs might
introduce some uncertainty about this. introduce some uncertainty about this.
The Packet Number field is set to a randomized value. The server
SHOULD send a packet with a short header and a packet number length
of 1 octet. Using the shortest possible packet number encoding
minimizes the perceived gap between the last packet that the server
sent and this packet. A server MAY indicate a different packet
number length, but a longer packet number encoding might allow this
message to be identified as a stateless reset more easily using
heuristics.
After the Packet Number, the server pads the message with an
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.
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. An
that supports multiple versions of QUIC needs to generate a stateless endpoint that supports multiple versions of QUIC needs to generate a
reset that will be accepted by clients that support any version that stateless reset that will be accepted by peers that support any
the server might support (or might have supported prior to losing version that the endpoint might support (or might have supported
state). Designers of new versions of QUIC need to be aware of this prior to losing state). Designers of new versions of QUIC need to be
and either reuse this design, or use a portion of the packet other aware of this and either reuse this design, or use a portion of the
than the last 16 octets for carrying data. packet other than the last 16 octets for carrying data.
6.10.4.1. Detecting a Stateless Reset 6.13.4.1. Detecting a Stateless Reset
A client detects a potential stateless reset when a packet with a An endpoint 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 endpoint 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 its peer, either in a
transport parameters. If these values are identical, the client MUST NEW_CONNECTION_ID frame or the server's transport parameters. If
enter the draining period and not send any further packets on this these values are identical, the endpoint MUST enter the draining
connection. If the comparison fails, the packet can be discarded. period and not send any further packets on this connection. If the
comparison fails, the packet can be discarded.
6.10.4.2. Calculating a Stateless Reset Token 6.13.4.2. 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, an endpoint 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
in a cluster or a storage problem for a server that might lose state. instances in a cluster or a storage problem for a endpoint that might
Stateless reset specifically exists to handle the case where state is lose state. Stateless reset specifically exists to handle the case
lost, so this approach is suboptimal. where state is 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,
the server's connection ID (see Section 4.7), and an identifier for the connection ID chosen by the endpoint (see Section 6.1), and an
the server instance. A server could use HMAC [RFC2104] (for example, instance identifier. An endpoint could use HMAC [RFC2104] (for
HMAC(static_key, server_id || connection_id)) or HKDF [RFC5869] (for example, HMAC(static_key, instance_id || connection_id)) or HKDF
example, using the static key as input keying material, with server [RFC5869] (for example, using the static key as input keying
and connection identifiers as salt). The output of this function is material, with instance and connection identifiers as salt). The
truncated to 16 octets to produce the Stateless Reset Token for that output of this function is truncated to 16 octets to produce the
connection. Stateless Reset Token for that connection.
A server that loses state can use the same method to generate a valid An endpoint that loses state can use the same method to generate a
Stateless Reset Secret. The connection ID comes from the packet that valid Stateless Reset Token. The connection ID comes from the packet
the server receives. that the endpoint receives. An instance that receives a packet for
another instance might be able to recover the instance identifier
using the connection ID. Alternatively, the instance identifier
might be omitted from the calculation of the Stateless Reset Token so
that all instances are equally able to generate a stateless reset.
This design relies on the client always sending a connection ID in This design relies on the peer always sending a connection ID in its
its packets so that the server can use the connection ID from a packets so that the endpoint can use the connection ID from a packet
packet to reset the connection. A server that uses this design to reset the connection. An endpoint that uses this design cannot
cannot allow clients to use a zero-length connection ID. allow its peers to send packets with a zero-length destination
connection ID.
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 instance, connection ID, and static key cannot occur for another
another connection. A connection ID from a connection that is reset connection. A connection ID from a connection that is reset by
by revealing the Stateless Reset Token cannot be reused for new 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 instance without first changing to use a
different static key or server identifier. different static key or instance identifier.
Note that Stateless Reset messages do not have any cryptographic Note that Stateless Reset messages do not have any cryptographic
protection. protection.
7. Frame Types and Formats 7. Frame Types and Formats
As described in Section 5, 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.
skipping to change at page 53, line 24 skipping to change at page 61, line 28
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:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Code (16) | Reason Phrase Length (i) ... | Error Code (16) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame Type (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 11.3 (APPLICATION_CLOSE uses codes from space defined in Section 11.3 (APPLICATION_CLOSE uses codes from
the application protocol error code space, see Section 11.4). the application protocol error code space, see Section 11.4).
Frame Type: The type of frame that triggered the error. A value of
0 (equivalent to the mention of the PADDING frame) is used when
the frame type is unknown.
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].
skipping to change at page 54, line 28 skipping to change at page 62, line 40
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Data (i) ... | Maximum Data (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields in the MAX_DATA frame are as follows: The fields in the MAX_DATA frame are as follows:
Maximum Data: A variable-length integer indicating the maximum Maximum Data: A variable-length integer indicating the maximum
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. The sum of
exception of data on stream 0. The sum of the largest received the largest received offsets on all streams - including streams in
offsets on all streams - including streams in terminal states, but terminal states - MUST NOT exceed the value advertised by a receiver.
excluding stream 0 - MUST NOT exceed the value advertised by a 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 6.4.2). result of a change in the initial limits (see Section 6.6.2).
7.7. 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.
skipping to change at page 55, line 36 skipping to change at page 63, line 46
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 6.4.2). limits (see Section 6.6.2).
7.8. 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
skipping to change at page 56, line 21 skipping to change at page 64, line 31
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 6.4.2). Section 6.6.2).
7.9. 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.
skipping to change at page 56, line 43 skipping to change at page 65, line 4
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 6.10). However, state in middleboxes might parameter (see Section 6.13). 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.
7.10. 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 10.2.1). BLOCKED frames can be used as input to tuning of Section 10.2.1). BLOCKED frames can be used as input to tuning of
skipping to change at page 58, line 30 skipping to change at page 66, line 36
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.
7.13. NEW_CONNECTION_ID Frame 7.13. NEW_CONNECTION_ID Frame
An endpoint sends a NEW_CONNECTION_ID frame (type=0x0b) to provide An endpoint sends a NEW_CONNECTION_ID frame (type=0x0b) to provide
its peer 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 6.8.5). linkability when migrating connections (see Section 6.11.5).
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) ... | Length (8) | Connection ID (32..144) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 59, line 21 skipping to change at page 67, line 39
Length: An 8-bit unsigned integer containing the length of the Length: An 8-bit unsigned integer containing the length of the
connection ID. Values less than 4 and greater than 18 are invalid connection ID. Values less than 4 and greater than 18 are invalid
and MUST be treated as a connection error of type and MUST be treated as a connection error of type
PROTOCOL_VIOLATION. PROTOCOL_VIOLATION.
Connection ID: A connection ID of the specified length. 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 6.10.4). Section 6.13.4).
An endpoint MUST NOT send this frame if it currently requires that An endpoint MUST NOT send this frame if it currently requires that
its peer send packets with a zero-length Destination Connection ID. its peer send packets with a zero-length Destination Connection ID.
Changing the length of a connection ID to or from zero-length makes 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. it difficult to identify when the value of the connection ID changed.
An endpoint that is sending packets with a zero-length Destination 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 ID MUST treat receipt of a NEW_CONNECTION_ID frame as a
connection error of type PROTOCOL_VIOLATION. connection error of type PROTOCOL_VIOLATION.
7.14. STOP_SENDING Frame 7.14. STOP_SENDING Frame
skipping to change at page 60, line 31 skipping to change at page 68, line 48
7.15. 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. The ACK frame contains any number they have received and processed. The ACK frame contains any number
of ACK blocks. ACK blocks are ranges of acknowledged packets. of ACK blocks. ACK blocks are ranges of acknowledged packets.
QUIC acknowledgements are irrevocable. Once acknowledged, a packet QUIC acknowledgements are irrevocable. Once acknowledged, a packet
remains acknowledged, even if it does not appear in a future ACK remains acknowledged, even if it does not appear in a future ACK
frame. This is unlike TCP SACKs ([RFC2018]). frame. This is unlike TCP SACKs ([RFC2018]).
It is expected that a sender will reuse the same packet number across
different packet number spaces. ACK frames only acknowledge the
packet numbers that were transmitted by the sender in the same packet
number space of the packet that the ACK was received in.
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.
An ACK frame is shown below. An ACK frame is shown below.
0 1 2 3 0 1 2 3
skipping to change at page 60, line 52 skipping to change at page 69, line 26
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Largest Acknowledged (i) ... | Largest Acknowledged (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Delay (i) ... | ACK Delay (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Block Count (i) ... | ACK Block Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Blocks (*) ... | ACK Blocks (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: ACK Frame Format Figure 9: ACK Frame Format
The fields in the ACK frame are as follows: The fields in the ACK frame are as follows:
Largest Acknowledged: A variable-length integer representing the Largest Acknowledged: A variable-length integer representing the
largest packet number the peer is acknowledging; this is usually largest packet number the peer is acknowledging; this is usually
the largest packet number that the peer has received prior to the largest packet number that the peer has received prior to
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 6.4.1). Scaling in this fashion multiplier of 8 (see Section 6.6.1). 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 7.15.1. been successfully received, see Section 7.15.1.
7.15.1. ACK Block Section 7.15.1. ACK Block Section
skipping to change at page 62, line 25 skipping to change at page 70, line 40
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Additional ACK Block (i) ... | Additional ACK Block (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Gap (i) ... | Gap (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Additional ACK Block (i) ... | Additional ACK Block (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: ACK Block Section Figure 10: ACK Block Section
Each ACK Block acknowledges a contiguous range of packets by Each ACK Block acknowledges a contiguous range of packets by
indicating the number of acknowledged packets that precede the indicating the number of acknowledged packets that precede the
largest packet number in that block. A value of zero indicates that largest packet number in that block. A value of zero indicates that
only the largest packet number is acknowledged. Larger ACK Block only the largest packet number is acknowledged. Larger ACK Block
values indicate a larger range, with corresponding lower values for values indicate a larger range, with corresponding lower values for
the smallest packet number in the range. Thus, given a largest the smallest packet number in the range. Thus, given a largest
packet number for the ACK, the smallest value is determined by the packet number for the ACK, the smallest value is determined by the
formula: formula:
skipping to change at page 63, line 9 skipping to change at page 71, line 25
the encoded value of the Gap Field. the encoded value of the Gap Field.
The value of the Gap field establishes the largest packet number The value of the Gap field establishes the largest packet number
value for the ACK block that follows the gap using the following value for the ACK block that follows the gap using the following
formula: formula:
largest = previous_smallest - gap - 2 largest = previous_smallest - gap - 2
If the calculated value for largest or smallest packet number for any If the calculated value for largest or smallest packet number for any
ACK Block is negative, an endpoint MUST generate a connection error ACK Block is negative, an endpoint MUST generate a connection error
of type FRAME_ERROR indicating an error in an ACK frame (that is, of type FRAME_ENCODING_ERROR indicating an error in an ACK frame.
0x10d).
The fields in the ACK Block Section are: The fields in the ACK Block Section are:
First ACK Block: A variable-length integer indicating the number of First ACK Block: A variable-length integer indicating the number of
contiguous packets preceding the Largest Acknowledged that are contiguous packets preceding the Largest Acknowledged that are
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.
skipping to change at page 63, line 48 skipping to change at page 72, line 16
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.
Because ACK frames are not sent in response to ACK-only packets, a Because ACK frames are not sent in response to ACK-only packets, a
receiver that is only sending ACK frames will only receive receiver that is only sending ACK frames will only receive
acknowledgements for its packets if the sender includes them in acknowledgements for its packets if the sender includes them in
packets with non-ACK frames. A sender SHOULD bundle ACK frames with packets with non-ACK frames. A sender SHOULD bundle ACK frames with
other frames when possible. other frames when possible.
Endpoints can only acknowledge packets sent in a particular packet
number space by sending ACK frames in packets from the same packet
number space.
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.
7.15.3. 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 MUST only be carried in a packet that has the same packet
packet that has an equivalent or greater level of packet protection. number space as the packet being ACKed (see Section 4.5). For
instance, packets that are protected with 1-RTT keys MUST be
Packets that are protected with 1-RTT keys MUST be acknowledged in 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
number that was sent with packet protection is not valid. An
unprotected packet that carries acknowledgments for protected packets
MUST be discarded in its entirety.
Packets that a client sends with 0-RTT packet protection MUST be Packets that a client sends with 0-RTT packet protection MUST be
acknowledged by the server in packets protected by 1-RTT keys. This acknowledged by the server in packets protected by 1-RTT keys. This
can mean that the client is unable to use these acknowledgments if can mean that the client is unable to use these acknowledgments if
the server cryptographic handshake messages are delayed or lost. the server cryptographic handshake messages are delayed or lost.
Note that the same limitation applies to other data sent by the Note that the same limitation applies to other data sent by the
server protected by the 1-RTT keys. server protected by the 1-RTT keys.
Unprotected packets, such as those that carry the initial Endpoints SHOULD send acknowledgments for packets containing CRYPTO
cryptographic handshake messages, MAY be acknowledged in unprotected frames with a reduced delay; see Section 3.5.1 of [QUIC-RECOVERY].
packets. Unprotected packets are vulnerable to falsification or
modification. Unprotected packets can be acknowledged along with
protected packets in a protected packet.
An endpoint SHOULD acknowledge packets containing cryptographic 7.16. ACK_ECN Frame
handshake messages in the next unprotected packet that it sends,
unless it is able to acknowledge those packets in later packets
protected by 1-RTT keys. At the completion of the cryptographic
handshake, both peers send unprotected packets containing
cryptographic handshake messages followed by packets protected by
1-RTT keys. An endpoint SHOULD acknowledge the unprotected packets
that complete the cryptographic handshake in a protected packet,
because its peer is guaranteed to have access to 1-RTT packet
protection keys.
For instance, a server acknowledges a TLS ClientHello in the packet The ACK_ECN frame (type=0x20) is used by an endpoint that supports
that carries the TLS ServerHello; similarly, a client can acknowledge ECN to acknowledge packets received with ECN codepoints of ECT(0),
a TLS HelloRetryRequest in the packet containing a second TLS ECT(1), or CE in the packet's IP header.
ClientHello. The complete set of server handshake messages (TLS
ServerHello through to Finished) might be acknowledged by a client in
protected packets, because it is certain that the server is able to
decipher the packet.
7.16. PATH_CHALLENGE Frame 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Largest Acknowledged (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Delay (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECT(0) Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECT(1) Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECN-CE Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Block Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Blocks (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: ACK_ECN Frame Format
An ACK_ECN frame contains all the elements of the ACK frame
(Section 7.15) with the addition of three counts following the ACK
Delay field.
ECT(0) Count: A variable-length integer representing the total
number packets received with the ECT(0) codepoint.
ECT(1) Count: A variable-length integer representing the total
number packets received with the ECT(1) codepoint.
CE Count: A variable-length integer representing the total number
packets received with the CE codepoint.
7.17. 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 path 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 65, line 20 skipping to change at page 74, line 4
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 7.17) containing the same Data. (Section 7.18) containing the same Data.
7.17. PATH_RESPONSE Frame 7.18. 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 7.16). frame (Section 7.17).
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.
7.18. STREAM Frames 7.19. NEW_TOKEN frame
A server sends a NEW_TOKEN frame (type=0x19) to provide the client a
token to send in a the header of an Initial packet for a future
connection.
The NEW_TOKEN frame is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Token Length (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Token (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields of a NEW_TOKEN frame are as follows:
Token Length: A variable-length integer specifying the length of the
token in bytes.
Token: An opaque blob that the client may use with a future Initial
packet.
7.20. 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
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (i) ... | Stream ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Offset (i)] ... | [Offset (i)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Length (i)] ... | [Length (i)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream Data (*) ... | Stream Data (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: STREAM Frame Format Figure 12: 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 9.1). 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.
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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.
7.21. CRYPTO Frame
The CRYPTO frame (type=0x18) is used to transmit cryptographic
handshake messages. It can be sent in all packet types. The CRYPTO
frame offers the cryptographic protocol an in-order stream of bytes.
CRYPTO frames are functionally identical to STREAM frames, except
that they do not bear a stream identifier; they are not flow
controlled; and they do not carry markers for optional offset,
optional length, and the end of the stream.
A CRYPTO frame is shown below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Offset (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Crypto Data (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: CRYPTO Frame Format
The CRYPTO frame contains the following fields:
Offset: A variable-length integer specifying the byte offset in the
stream for the data in this CRYPTO frame.
Length: A variable-length integer specifying the length of the
Crypto Data field in this CRYPTO frame.
Crypto Data: The cryptographic message data.
There is a separate flow of cryptographic handshake data in each
encryption level, each of which starts at an offset of 0. This
implies that each encryption level is treated as a separate CRYPTO
stream of data.
Unlike STREAM frames, which include a Stream ID indicating to which
stream the data belongs, the CRYPTO frame carries data for a single
stream per encryption level. The stream does not have an explicit
end, so CRYPTO frames do not have a FIN bit.
8. Packetization and Reliability 8. Packetization and Reliability
A sender bundles one or more frames in a QUIC packet (see Section 5). 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
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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 Data sent in CRYPTO frames are retransmitted according to the
rules in [QUIC-RECOVERY], until either all data has been
acknowledged or the crypto state machine implicitly knows that the
peer received the data.
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 7.15.2. 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
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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 9.3. 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 6.10. when packet loss is detected, but as described in Section 6.13.
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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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.
8.4.1. Special Considerations for PMTU Discovery 8.4.1. IPv4 PMTU Discovery
Traditional ICMP-based path MTU discovery in IPv4 [PMTUDv4] is Traditional ICMP-based path MTU discovery in IPv4 [PMTUDv4] 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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| | | | | |
| 0x1 | Server-Initiated, Bidirectional | | 0x1 | Server-Initiated, Bidirectional |
| | | | | |
| 0x2 | Client-Initiated, Unidirectional | | 0x2 | Client-Initiated, Unidirectional |
| | | | | |
| 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 The first bi-directional stream opened by the client is stream 0.
used for the cryptographic handshake. Stream 0 MUST NOT be used for
application data.
A QUIC endpoint MUST NOT reuse a Stream ID. Streams can be used in A QUIC endpoint MUST NOT reuse a Stream ID. Streams can be used in
any order. Streams that are used out of order result in opening all any order. Streams that are used out of order result in opening 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 7.1). Section 7.1).
9.2. Stream States 9.2. Stream States
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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.
9.2.1. Send Stream States 9.2.1. Send Stream States
Figure 10 shows the states for the part of a stream that sends data Figure 14 shows the states for the part of a stream that sends data
to a peer. to a peer.
o o
| Create Stream (Sending) | Create Stream (Sending)
| Create Bidirectional Stream (Receiving) | Create Bidirectional Stream (Receiving)
v v
+-------+ +-------+
| Ready | Send RST_STREAM | Ready | Send RST_STREAM
| |-----------------------. | |-----------------------.
+-------+ | +-------+ |
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| Sent +------------------>| Sent | | Sent +------------------>| Sent |
+-------+ +-------+ +-------+ +-------+
| | | |
| Recv All ACKs | Recv ACK | Recv All ACKs | Recv ACK
v v v v
+-------+ +-------+ +-------+ +-------+
| Data | | Reset | | Data | | Reset |
| Recvd | | Recvd | | Recvd | | Recvd |
+-------+ +-------+ +-------+ +-------+
Figure 10: States for Send Streams Figure 14: 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 "Ready" 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 "Ready" 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.
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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.
9.2.2. Receive Stream States 9.2.2. Receive Stream States
Figure 11 shows the states for the part of a stream that receives Figure 15 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 "Ready" 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
| Create Bidirectional Stream (Sending) | Create Bidirectional Stream (Sending)
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| Recvd +<-- (optional) --->| Recvd | | Recvd +<-- (optional) --->| Recvd |
+-------+ +-------+ +-------+ +-------+
| | | |
| App Read All Data | App Read RST | App Read All Data | App Read RST
v v v v
+-------+ +-------+ +-------+ +-------+
| Data | | Reset | | Data | | Reset |
| Read | | Read | | Read | | Read |
+-------+ +-------+ +-------+ +-------+
Figure 11: States for Receive Streams Figure 15: States for Receive Streams
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,
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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.
9.2.3. 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 7.18), STREAM_BLOCKED (Section 7.11), and RST_STREAM (Section 7.20), STREAM_BLOCKED (Section 7.11), and RST_STREAM
(Section 7.3). (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 7.7) and The receiver of a stream sends MAX_STREAM_DATA (Section 7.7) and
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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.
9.4. 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 6.4.1) and is subsequently transport parameters (see Section 6.6.1) and is subsequently
increased by MAX_STREAM_ID frames (see Section 7.8). 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 11), 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 6.4.2). offsets (see Section 6.6.2).
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.
9.5. 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
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an ordered byte-stream requires that an endpoint buffer any data that an ordered byte-stream requires that an endpoint buffer any data that
is received out of order, up to the advertised flow control limit. is received out of order, up to the advertised flow control limit.
An endpoint could receive the same octets multiple times; octets that An endpoint could receive the same octets multiple times; octets that
have already been received can be discarded. The value for a given have already been received can be discarded. The value for a given
octet MUST NOT change if it is sent multiple times; an endpoint MAY octet MUST NOT change if it is sent multiple times; an endpoint MAY
treat receipt of a changed octet as a connection error of type treat receipt of a changed octet as a connection error of type
PROTOCOL_VIOLATION. PROTOCOL_VIOLATION.
An endpoint MUST NOT send data on any stream without ensuring that it An endpoint MUST NOT send data on any stream without ensuring that it
is within the data limits set by its peer. The cryptographic is within the data limits set by its peer.
handshake stream, Stream 0, is exempt from the connection-level data
limits established by MAX_DATA. Data on stream 0 other than the
initial cryptographic handshake message is still subject to stream-
level data limits and MAX_STREAM_DATA. This message is exempt from
flow control because it needs to be sent in a single packet
regardless of the server's flow control state. This rule applies
even for 0-RTT handshakes where the remembered value of
MAX_STREAM_DATA would not permit sending a full initial cryptographic
handshake message.
Flow control is described in detail in Section 10, 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].
9.6. 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
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Stream priority is most relevant when deciding which stream data will Stream priority is most relevant when deciding which stream data will
be transmitted. Often, there will be limits on what can be be transmitted. Often, there will be limits on what can be
transmitted as a result of connection flow control or the current transmitted as a result of connection flow control or the current
congestion controller state. congestion controller state.
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 CRYPTO frames SHOULD 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 data in frames 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.
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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
connection. This leads to two levels of flow control in QUIC: (i) connection. This leads to two levels of flow control in QUIC: (i)
Connection flow control, which prevents senders from exceeding a Connection flow control, which prevents senders from exceeding a
receiver's buffer capacity for the connection, and (ii) Stream flow receiver's buffer capacity for the connection, and (ii) Stream flow
control, which prevents a single stream from consuming the entire control, which prevents a single stream from consuming the entire
receive buffer for a connection. receive buffer for a connection.
A data receiver sends MAX_STREAM_DATA or MAX_DATA frames to the A data receiver sends MAX_STREAM_DATA or MAX_DATA frames to the
sender to advertise additional credit. MAX_STREAM_DATA frames send sender to advertise additional credit. MAX_STREAM_DATA frames send
the the maximum absolute byte offset of a stream, while MAX_DATA the maximum absolute byte offset of a stream, while MAX_DATA sends
sends the maximum sum of the absolute byte offsets of all streams the maximum of the sum of the absolute byte offsets of all streams.
other than stream 0.
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
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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
the flow control offset to be advertised. A receiver MAY send the flow control offset to be advertised. A receiver MAY send
MAX_STREAM_DATA frames in multiple packets in order to make sure that MAX_STREAM_DATA frames in multiple packets in order to make sure that
the sender receives an update before running out of flow control the sender receives an update before running out of flow control
credit, even if one of the packets is lost. credit, even if one of the packets is lost.
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. A receiver advertises credit
advertises credit for a connection by sending a MAX_DATA frame. A for a connection by sending a MAX_DATA frame. A receiver maintains a
receiver maintains a cumulative sum of bytes received on all cumulative sum of bytes received on all contributing streams, which
contributing streams, which are used to check for flow control are used to check for flow control violations. A receiver might use
violations. A receiver might use a sum of bytes consumed on all a sum of bytes consumed on all contributing streams to determine the
contributing streams to determine the maximum data limit to be maximum data limit to be advertised.
advertised.
10.1. 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
skipping to change at page 86, line 15 skipping to change at page 96, line 5
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 round-trip 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.
10.1.3. Handshake Exemption
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
initial stream flow control window. Since MAX_STREAM_DATA frames are
not permitted in these early packets, the peer cannot provide
additional flow control window in order to complete the handshake.
Endpoints MAY exceed the flow control limits on stream 0 prior to the
completion of the cryptographic handshake. (That is, in Initial,
Retry, and Handshake packets.) However, once the handshake is
complete, endpoints MUST NOT send additional data beyond the peer's
permitted offset. If the amount of data sent during the handshake
exceeds the peer's maximum offset, the endpoint cannot send
additional data on stream 0 until the peer has sent a MAX_STREAM_DATA
frame indicating a larger maximum offset.
10.2. 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
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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 11). 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.
10.4. Flow Control for Crytographic Handshake
Data sent in CRYPTO frames is not flow controlled in the same way as
STREAM frames. QUIC relies on the cryptographic protocol
implementation to avoid excessive buffering of data, see [QUIC-TLS].
The implementation SHOULD provide an interface to QUIC to tell it
about its buffering limits so that there is not excessive buffering
at multiple layers.
11. 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. Both transport-level and application-level errors error to its peer. Both transport-level and application-level errors
can affect an entire connection (see Section 11.1), while only can affect an entire connection (see Section 11.1), while only
application-level errors can be isolated to a single stream (see application-level errors can be isolated to a single stream (see
Section 11.2). Section 11.2).
The most appropriate error code (Section 11.3) 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 6.10.4) is not suitable for any error that A stateless reset (Section 6.13.4) 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.
11.1. 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 7.4, CONNECTION_CLOSE or APPLICATION_CLOSE frame (Section 7.4,
skipping to change at page 88, line 43 skipping to change at page 98, line 22
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 6.10.4). stateless reset process (Section 6.13.4).
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.
11.2. Stream Errors 11.2. Stream Errors
If an application-level error affects a single stream, but otherwise If an application-level error affects a single stream, but otherwise
leaves the connection in a recoverable state, the endpoint can send a leaves the connection in a recoverable state, the endpoint can send a
RST_STREAM frame (Section 7.3) with an appropriate error code to RST_STREAM frame (Section 7.3) with an appropriate error code to
terminate just the affected stream. terminate just the affected stream.
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
the FIN flag, an endpoint MUST generate a connection error of type
PROTOCOL_VIOLATION.
Other than STOPPING (Section 9.3), RST_STREAM MUST be instigated by Other than STOPPING (Section 9.3), RST_STREAM MUST be instigated by
the application and MUST carry an application error code. Resetting the application and MUST carry an application error code. Resetting
a stream without knowledge of the application protocol could cause a stream without knowledge of the application protocol could cause
the protocol to enter an unrecoverable state. Application protocols the protocol to enter an unrecoverable state. Application protocols
might require certain streams to be reliably delivered in order to might require certain streams to be reliably delivered in order to
guarantee consistent state between endpoints. guarantee consistent state between endpoints.
11.3. Transport Error Codes 11.3. Transport Error Codes
QUIC error codes are 16-bit unsigned integers. QUIC error codes are 16-bit unsigned integers.
skipping to change at page 90, line 13 skipping to change at page 99, line 29
Section 9.2). 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_ENCODING_ERROR (0x7): An endpoint received a frame that was
badly formatted. For instance, an empty STREAM frame that omitted badly formatted. For instance, an empty STREAM frame that omitted
the FIN flag, or an ACK frame that has more acknowledgment ranges the FIN flag, or an ACK frame that has more acknowledgment ranges
than the remainder of the packet could carry. This is a generic than the remainder of the packet could carry.
error code; an endpoint SHOULD use the more specific frame format
error codes (0x1XX) if possible.
TRANSPORT_PARAMETER_ERROR (0x8): An endpoint received transport TRANSPORT_PARAMETER_ERROR (0x8): An endpoint received transport
parameters that were badly formatted, included an invalid value, parameters that were badly formatted, included an invalid value,
was absent even though it is mandatory, was present though it is was absent even though it is mandatory, was present though it is
forbidden, or is otherwise in error. forbidden, or is otherwise in error.
VERSION_NEGOTIATION_ERROR (0x9): An endpoint received transport VERSION_NEGOTIATION_ERROR (0x9): An endpoint received transport
parameters that contained version negotiation parameters that parameters that contained version negotiation parameters that
disagreed with the version negotiation that it performed. This disagreed with the version negotiation that it performed. This
error code indicates a potential version downgrade attack. error code indicates a potential version downgrade attack.
PROTOCOL_VIOLATION (0xA): An endpoint detected an error with PROTOCOL_VIOLATION (0xA): An endpoint detected an error with
protocol compliance that was not covered by more specific error protocol compliance that was not covered by more specific error
codes. codes.
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 INVALID_MIGRATION (0xC): A peer has migrated to a different network
frame type. The frame type is included as the last octet of the when the endpoint had disabled migration.
error code. For example, an error in a MAX_STREAM_ID frame would
be indicated with the code (0x106).
Codes for errors occuring when TLS is used for the crypto handshake CRYPTO_ERROR (0x1XX): The cryptographic handshake failed. A range
are defined in Section 11 of [QUIC-TLS]. See Section 13.2 for of 256 values is reserved for carrying error codes specific to the
details of registering new error codes. cryptographic handshake that is used. Codes for errors occuring
when TLS is used for the crypto handshake are defined in
Section 11 of [QUIC-TLS].
See Section 13.3 for details of registering new error codes.
11.4. 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 7.3) and APPLICATION_CLOSE (Section 7.5) 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.
12. Security Considerations 12. Security Considerations
12.1. Spoofed ACK Attack 12.1. Handshake Denial of Service
As an encrypted and authenticated transport QUIC provides a range of
protections against denial of service. Once the cryptographic
handshake is complete, QUIC endpoints discard most packets that are
not authenticated, greatly limiting the ability of an attacker to
interfere with existing connections.
Once a connection is established QUIC endpoints might accept some
unauthenticated ICMP packets (see Section 8.4.1), but the use of
these packets is extremely limited. The only other type of packet
that an endpoint might accept is a stateless reset (Section 6.13.4)
which relies on the token being kept secret until it is used.
During the creation of a connection, QUIC only provides protection
against attack from off the network path. All QUIC packets contain
proof that the recipient saw a preceding packet from its peer.
The first mechanism used is the source and destination connection
IDs, which are required to match those set by a peer. Except for an
Initial and stateless reset packets, an endpoint only accepts packets
that include a destination connection that matches a connection ID
the endpoint previously chose. This is the only protection offered
for Version Negotiation packets.
The destination connection ID in an Initial packet is selected by a
client to be unpredictable, which serves an additional purpose. The
packets that carry the cryptographic handshake are protected with a
key that is derived from this connection ID and salt specific to the
QUIC version. This allows endpoints to use the same process for
authenticating packets that they receive as they use after the
cryptographic handshake completes. Packets that cannot be
authenticated are discarded. Protecting packets in this fashion
provides a strong assurance that the sender of the packet saw the
Initial packet and understood it.
These protections are not intended to be effective against an
attacker that is able to receive QUIC packets prior to the connection
being established. Such an attacker can potentially send packets
that will be accepted by QUIC endpoints. This version of QUIC
attempts to detect this sort of attack, but it expects that endpoints
will fail to establish a connection rather than recovering. For the
most part, the cryptographic handshake protocol [QUIC-TLS] is
responsible for detecting tampering during the handshake, though
additional validation is required for version negotiation (see
Section 6.6.4).
Endpoints are permitted to use other methods to detect and attempt to
recover from interference with the handshake. Invalid packets may be
identified and discarded using other methods, but no specific method
is mandated in this document.
12.2. 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 6.6) from the server and then release the IP address it used (Section 6.9) 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
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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.
12.2. Optimistic ACK Attack 12.3. Optimistic ACK Attack
An endpoint that acknowledges packets it has not received might cause An endpoint that acknowledges packets it has not received might cause
a congestion controller to permit sending at rates beyond what the a congestion controller to permit sending at rates beyond what the
network supports. An endpoint MAY skip packet numbers when sending network supports. An endpoint MAY skip packet numbers when sending
packets to detect this behavior. An endpoint can then immediately packets to detect this behavior. An endpoint can then immediately
close the connection with a connection error of type close the connection with a connection error of type
PROTOCOL_VIOLATION (see Section 6.10.3). PROTOCOL_VIOLATION (see Section 6.13.3).
12.3. Slowloris Attacks 12.4. 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.
12.4. Stream Fragmentation and Reassembly Attacks 12.5. 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.
12.5. Stream Commitment Attack 12.6. 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 9.1. 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 9.4. 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.
13. IANA Considerations 12.7. Explicit Congestion Notification Attacks
An on-path attacker could manipulate the value of ECN codepoints in
the IP header to influence the sender's rate. [RFC3168] discusses
manipulations and their effects in more detail.
An on-the-side attacker can duplicate and send packets with modified
ECN codepoints to affect the sender's rate. If duplicate packets are
discarded by a receiver, an off-path attacker will need to race the
duplicate packet against the original to be successful in this
attack. Therefore, QUIC receivers ignore ECN codepoints set in
duplicate packets (see Section 6.8).
13. IANA Considerations
13.1. 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
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Value: The numeric value of the assignment (registrations will be Value: The numeric value of the assignment (registrations will be
between 0x0000 and 0xfeff). between 0x0000 and 0xfeff).
Parameter Name: A short mnemonic for the parameter. Parameter Name: A short mnemonic for the parameter.
Specification: A reference to a publicly available specification for Specification: A reference to a publicly available specification for
the value. the value.
The nominated expert(s) verify that a specification exists and is The nominated expert(s) verify that a specification exists and is
readily accessible. The expert(s) are encouraged to be biased readily accessible. Expert(s) are encouraged to be biased towards
towards approving registrations unless they are abusive, frivolous, approving registrations unless they are abusive, frivolous, or
or actively harmful (not merely aesthetically displeasing, 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 6.4.1 | | 0x0000 | initial_max_stream_data | Section 6.6.1 |
| | | | | | | |
| 0x0001 | initial_max_data | Section 6.4.1 | | 0x0001 | initial_max_data | Section 6.6.1 |
| | | | | | | |
| 0x0002 | initial_max_bidi_streams | Section 6.4.1 | | 0x0002 | initial_max_bidi_streams | Section 6.6.1 |
| | | | | | | |
| 0x0003 | idle_timeout | Section 6.4.1 | | 0x0003 | idle_timeout | Section 6.6.1 |
| | | | | | | |
| 0x0004 | preferred_address | Section 6.4.1 | | 0x0004 | preferred_address | Section 6.6.1 |
| | | | | | | |
| 0x0005 | max_packet_size | Section 6.4.1 | | 0x0005 | max_packet_size | Section 6.6.1 |
| | | | | | | |
| 0x0006 | stateless_reset_token | Section 6.4.1 | | 0x0006 | stateless_reset_token | Section 6.6.1 |
| | | | | | | |
| 0x0007 | ack_delay_exponent | Section 6.4.1 | | 0x0007 | ack_delay_exponent | Section 6.6.1 |
| | | | | | | |
| 0x0008 | initial_max_uni_streams | Section 6.4.1 | | 0x0008 | initial_max_uni_streams | Section 6.6.1 |
+--------+--------------------------+---------------+ +--------+--------------------------+---------------+
Table 7: Initial QUIC Transport Parameters Entries Table 7: Initial QUIC Transport Parameters Entries
13.2. QUIC Transport Error Codes Registry 13.2. QUIC Frame Type Registry
IANA [SHALL add/has added] a registry for "QUIC Frame Types" under a
"QUIC Protocol" heading.
The "QUIC Frame Types" registry governs a 62-bit space. This space
is split into three spaces that are governed by different policies.
Values between 0x00 and 0x3f (in hexadecimal) are assigned via the
Standards Action or IESG Review policies [RFC8126]. Values from 0x40
to 0x3fff operate on the Specification Required policy [RFC8126].
All other values are assigned to Private Use [RFC8126].
Registrations MUST include the following fields:
Value: The numeric value of the assignment (registrations will be
between 0x00 and 0x3fff). A range of values MAY be assigned.
Frame Name: A short mnemonic for the frame type.
Specification: A reference to a publicly available specification for
the value.
The nominated expert(s) verify that a specification exists and is
readily accessible. Specifications for new registrations need to
describe the means by which an endpoint might determine that it can
send the identified type of frame. An accompanying transport
parameter registration (see Section 13.1) is expected for most
registrations. The specification needs to describe the format and
assigned semantics of any fields in the frame.
Expert(s) are encouraged to be biased towards approving registrations
unless they are abusive, frivolous, or actively harmful (not merely
aesthetically displeasing, or architecturally dubious).
The initial contents of this registry are tabulated in Table 3.
13.3. 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 95, line 5 skipping to change at page 106, line 41
between 0x0000 and 0xfeff). between 0x0000 and 0xfeff).
Code: A short mnemonic for the parameter. Code: A short mnemonic for the parameter.
Description: A brief description of the error code semantics, which Description: A brief description of the error code semantics, which
MAY be a summary if a specification reference is provided. MAY be a summary if a specification reference is provided.
Specification: A reference to a publicly available specification for Specification: A reference to a publicly available specification for
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. Values
that FRAME_ERROR takes the range from 0x100 to 0x1FF and private use from 0xFF00 to 0xFFFF are reserved for Private Use [RFC8126].
occupies the range from 0xFE00 to 0xFFFF.
+-----------+------------------------+---------------+--------------+ +------+---------------------------+----------------+---------------+
| Value | Error | Description | Specificatio | | Valu | Error | Description | Specification |
| | | | n | | e | | | |
+-----------+------------------------+---------------+--------------+ +------+---------------------------+----------------+---------------+
| 0x0 | NO_ERROR | No error | Section 11.3 | | 0x0 | NO_ERROR | No error | Section 11.3 |
| | | | | | | | | |
| 0x1 | INTERNAL_ERROR | Implementatio | Section 11.3 | | 0x1 | INTERNAL_ERROR | Implementation | Section 11.3 |
| | | n error | | | | | error | |
| | | | | | | | | |
| 0x2 | SERVER_BUSY | Server | Section 11.3 | | 0x2 | SERVER_BUSY | Server | Section 11.3 |
| | | currently | | | | | currently busy | |
| | | busy | | | | | | |
| | | | | | 0x3 | FLOW_CONTROL_ERROR | Flow control | Section 11.3 |
| 0x3 | FLOW_CONTROL_ERROR | Flow control | Section 11.3 | | | | error | |
| | | error | | | | | | |
| | | | | | 0x4 | STREAM_ID_ERROR | Invalid stream | Section 11.3 |
| 0x4 | STREAM_ID_ERROR | Invalid | Section 11.3 | | | | ID | |
| | | stream ID | | | | | | |
| | | | | | 0x5 | STREAM_STATE_ERROR | Frame received | Section 11.3 |
| 0x5 | STREAM_STATE_ERROR | Frame | Section 11.3 | | | | in invalid | |
| | | received in | | | | | stream state | |
| | | invalid | | | | | | |
| | | stream state | | | 0x6 | FINAL_OFFSET_ERROR | Change to | Section 11.3 |
| | | | | | | | final stream | |
| 0x6 | FINAL_OFFSET_ERROR | Change to | Section 11.3 | | | | offset | |
| | | final stream | | | | | | |
| | | offset | | | 0x7 | FRAME_ENCODING_ERROR | Frame encoding | Section 11.3 |
| | | | | | | | error | |
| 0x7 | FRAME_FORMAT_ERROR | Generic frame | Section 11.3 | | | | | |
| | | format error | | | 0x8 | TRANSPORT_PARAMETER_ERROR | Error in | Section 11.3 |
| | | | | | | | transport | |
| 0x8 | TRANSPORT_PARAMETER_ER | Error in | Section 11.3 | | | | parameters | |
| | ROR | transport | | | | | | |
| | | parameters | | | 0x9 | VERSION_NEGOTIATION_ERROR | Version | Section 11.3 |
| | | | | | | | negotiation | |
| 0x9 | VERSION_NEGOTIATION_ER | Version | Section 11.3 | | | | failure | |
| | ROR | negotiation | | | | | | |
| | | failure | | | 0xA | PROTOCOL_VIOLATION | Generic | Section 11.3 |
| | | | | | | | protocol | |
| 0xA | PROTOCOL_VIOLATION | Generic | Section 11.3 | | | | violation | |
| | | protocol | | | | | | |
| | | violation | | | 0xB | UNSOLICITED_PATH_RESPONSE | Unsolicited | Section 11.3 |
| | | | | | | | PATH_RESPONSE | |
| 0xB | UNSOLICITED_PATH_RESPO | Unsolicited | Section 11.3 | | | | frame | |
| | NSE | PATH_RESPONSE | | | | | | |
| | | frame | | | 0xC | INVALID_MIGRATION | Violated | Section 11.3 |
| | | | | | | | disabled | |
| 0x100-0x1 | FRAME_ERROR | Specific | Section 11.3 | | | | migration | |
| FF | | frame format | | +------+---------------------------+----------------+---------------+
| | | error | |
+-----------+------------------------+---------------+--------------+
Table 8: Initial QUIC Transport Error Codes Entries Table 8: Initial QUIC Transport Error Codes Entries
14. References 14. References
14.1. 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),
skipping to change at page 96, line 38 skipping to change at page 108, line 29
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>.
[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-12 (work and Congestion Control", draft-ietf-quic-recovery-13 (work
in progress), May 2018. in progress), June 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-12 (work in progress), May 2018. tls-13 (work in progress), June 2018.
[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>.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
of Explicit Congestion Notification (ECN) to IP",
RFC 3168, DOI 10.17487/RFC3168, September 2001,
<https://www.rfc-editor.org/info/rfc3168>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <https://www.rfc-editor.org/info/rfc3629>. 2003, <https://www.rfc-editor.org/info/rfc3629>.
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086, "Randomness Requirements for Security", BCP 106, RFC 4086,
DOI 10.17487/RFC4086, June 2005, DOI 10.17487/RFC4086, June 2005,
<https://www.rfc-editor.org/info/rfc4086>. <https://www.rfc-editor.org/info/rfc4086>.
[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>.
[RFC8311] Black, D., "Relaxing Restrictions on Explicit Congestion
Notification (ECN) Experimentation", RFC 8311,
DOI 10.17487/RFC8311, January 2018,
<https://www.rfc-editor.org/info/rfc8311>.
14.2. 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-01 (work in progress), May draft-ietf-quic-invariants-01 (work in progress), June
2018. 2018.
[RFC2018] Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP [RFC2018] Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP
Selective Acknowledgment Options", RFC 2018, Selective Acknowledgment Options", RFC 2018,
DOI 10.17487/RFC2018, October 1996, DOI 10.17487/RFC2018, October 1996,
<https://www.rfc-editor.org/info/rfc2018>. <https://www.rfc-editor.org/info/rfc2018>.
[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,
skipping to change at page 98, line 29 skipping to change at page 110, line 29
[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.
Appendix A. Contributors Appendix A. Change Log
The original authors of this specification were Ryan Hamilton, Jana *RFC Editor's Note:* Please remove this section prior to
Iyengar, Ian Swett, and Alyssa Wilk. publication of a final version of this document.
The original design and rationale behind this protocol draw Issue and pull request numbers are listed with a leading octothorp.
significantly from work by Jim Roskind [EARLY-DESIGN]. In
alphabetical order, the contributors to the pre-IETF QUIC project at
Google are: Britt Cyr, Jeremy Dorfman, Ryan Hamilton, Jana Iyengar,
Fedor Kouranov, Charles Krasic, Jo Kulik, Adam Langley, Jim Roskind,
Robbie Shade, Satyam Shekhar, Cherie Shi, Ian Swett, Raman Tenneti,
Victor Vasiliev, Antonio Vicente, Patrik Westin, Alyssa Wilk, Dale
Worley, Fan Yang, Dan Zhang, Daniel Ziegler.
Appendix B. Acknowledgments A.1. Since draft-ietf-quic-transport-12
Special thanks are due to the following for helping shape pre-IETF o Changes to integration of the TLS handshake (#829, #1018, #1094,
QUIC and its deployment: Chris Bentzel, Misha Efimov, Roberto Peon, #1165, #1190, #1233, #1242, #1252, #1450)
Alistair Riddoch, Siddharth Vijayakrishnan, and Assar Westerlund.
This document has benefited immensely from various private * The cryptographic handshake uses CRYPTO frames, not stream 0
discussions and public ones on the quic@ietf.org and proto-
quic@chromium.org mailing lists. Our thanks to all.
Appendix C. Change Log * QUIC packet protection is used in place of TLS record
protection
*RFC Editor's Note:* Please remove this section prior to * Separate QUIC packet number spaces are used for the handshake
publication of a final version of this document.
Issue and pull request numbers are listed with a leading octothorp. * Changed Retry to be independent of the cryptographic handshake
C.1. Since draft-ietf-quic-transport-11 * Added NEW_TOKEN frame and Token fields to Initial packet
* Limit the use of HelloRetryRequest to address TLS needs (like
key shares)
o Enable server to transition connections to a preferred address
(#560, #1251, #1373)
o Added ECN feedback mechanisms and handling; new ACK_ECN frame
(#804, #805, #1372)
o Changed rules and recommendations for use of new connection IDs
(#1258, #1264, #1276, #1280, #1419, #1452, #1453, #1465)
o Added a transport parameter to disable intentional connection
migration (#1271, #1447)
o Packets from different connection ID can't be coalesced (#1287,
#1423)
o Fixed sampling method for packet number encryption; the length
field in long headers includes the packet number field in addition
to the packet payload (#1387, #1389)
o Stateless Reset is now symmetric and subject to size constraints
(#466, #1346)
o Added frame type extension mechanism (#58, #1473)
A.2. Since draft-ietf-quic-transport-11
o Enable server to transition connections to a preferred address o Enable server to transition connections to a preferred address
(#560, #1251) (#560, #1251)
o Packet numbers are encrypted (#1174, #1043, #1048, #1034, #850, o Packet numbers are encrypted (#1174, #1043, #1048, #1034, #850,
#990, #734, #1079) #990, #734, #1317, #1267, #1079)
o Packet numbers use a variable-length encoding (#989, #1334) o Packet numbers use a variable-length encoding (#989, #1334)
o STREAM frames can now be empty (#1350) o STREAM frames can now be empty (#1350)
C.2. Since draft-ietf-quic-transport-10 A.3. Since draft-ietf-quic-transport-10
o Swap payload length and packed number fields in long header o Swap payload length and packed number fields in long header
(#1294) (#1294)
o Clarified that CONNECTION_CLOSE is allowed in Handshake packet o Clarified that CONNECTION_CLOSE is allowed in Handshake packet
(#1274) (#1274)
o Spin bit reserved (#1283) o Spin bit reserved (#1283)
o Coalescing multiple QUIC packets in a UDP datagram (#1262, #1285) o Coalescing multiple QUIC packets in a UDP datagram (#1262, #1285)
o A more complete connection migration (#1249) o A more complete connection migration (#1249)
o Refine opportunistic ACK defense text (#305, #1030, #1185) o Refine opportunistic ACK defense text (#305, #1030, #1185)
o A Stateless Reset Token isn't mandatory (#818, #1191) o A Stateless Reset Token isn't mandatory (#818, #1191)
o Removed implicit stream opening (#896, #1193) o Removed implicit stream opening (#896, #1193)
skipping to change at page 100, line 4 skipping to change at page 112, line 21
o Removed implicit stream opening (#896, #1193) o Removed implicit stream opening (#896, #1193)
o An empty STREAM frame can be used to open a stream without sending o An empty STREAM frame can be used to open a stream without sending
data (#901, #1194) data (#901, #1194)
o Define stream counts in transport parameters rather than a maximum o Define stream counts in transport parameters rather than a maximum
stream ID (#1023, #1065) stream ID (#1023, #1065)
o STOP_SENDING is now prohibited before streams are used (#1050) o STOP_SENDING is now prohibited before streams are used (#1050)
o Recommend including ACK in Retry packets and allow PADDING (#1067, o Recommend including ACK in Retry packets and allow PADDING (#1067,
#882) #882)
o Endpoints now become closing after an idle timeout (#1178, #1179) o Endpoints now become closing after an idle timeout (#1178, #1179)
o Remove implication that Version Negotiation is sent when a packet o Remove implication that Version Negotiation is sent when a packet
of the wrong version is received (#1197) of the wrong version is received (#1197)
C.3. Since draft-ietf-quic-transport-09 A.4. 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, #725, #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)
skipping to change at page 100, line 33 skipping to change at page 113, line 4
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, #825, #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)
o Endpoints now set the connection ID that their peer uses. o Endpoints now set the connection ID that their peer uses.
Connection IDs are variable length. Removed the Connection IDs are variable length. Removed the
omit_connection_id transport parameter and the corresponding short omit_connection_id transport parameter and the corresponding short
header flag. (#1089, #1052, #1146, #821, #745, #821, #1166, #1151) header flag. (#1089, #1052, #1146, #821, #745, #821, #1166, #1151)
C.4. Since draft-ietf-quic-transport-08 A.5. 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)
skipping to change at page 101, line 19 skipping to change at page 113, line 37
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.5. Since draft-ietf-quic-transport-07 A.6. 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)
skipping to change at page 102, line 15 skipping to change at page 114, line 33
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.6. Since draft-ietf-quic-transport-06 A.7. 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.7. Since draft-ietf-quic-transport-05 A.8. 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.8. Since draft-ietf-quic-transport-04 A.9. 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)
skipping to change at page 103, line 34 skipping to change at page 116, line 5
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.9. Since draft-ietf-quic-transport-03 A.10. 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.10. Since draft-ietf-quic-transport-02 A.11. 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)
skipping to change at page 104, line 31 skipping to change at page 117, line 4
* BLOCKED split to match WINDOW_UPDATE split (#454) * BLOCKED split to match WINDOW_UPDATE split (#454)
* Define STREAM_ID_NEEDED frame (#455) * Define STREAM_ID_NEEDED frame (#455)
o A NEW_CONNECTION_ID frame supports connection migration without o A NEW_CONNECTION_ID frame supports connection migration without
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.11. Since draft-ietf-quic-transport-01 A.12. 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)
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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.12. Since draft-ietf-quic-transport-00 A.13. 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.13. Since draft-hamilton-quic-transport-protocol-01 A.14. 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
Acknowledgments
Special thanks are due to the following for helping shape pre-IETF
QUIC and its deployment: Chris Bentzel, Misha Efimov, Roberto Peon,
Alistair Riddoch, Siddharth Vijayakrishnan, and Assar Westerlund.
This document has benefited immensely from various private
discussions and public ones on the quic@ietf.org and proto-
quic@chromium.org mailing lists. Our thanks to all.
Contributors
The original authors of this specification were Ryan Hamilton, Jana
Iyengar, Ian Swett, and Alyssa Wilk.
The original design and rationale behind this protocol draw
significantly from work by Jim Roskind [EARLY-DESIGN]. In
alphabetical order, the contributors to the pre-IETF QUIC project at
Google are: Britt Cyr, Jeremy Dorfman, Ryan Hamilton, Jana Iyengar,
Fedor Kouranov, Charles Krasic, Jo Kulik, Adam Langley, Jim Roskind,
Robbie Shade, Satyam Shekhar, Cherie Shi, Ian Swett, Raman Tenneti,
Victor Vasiliev, Antonio Vicente, Patrik Westin, Alyssa Wilk, Dale
Worley, Fan Yang, Dan Zhang, Daniel Ziegler.
Authors' Addresses Authors' Addresses
Jana Iyengar (editor) Jana Iyengar (editor)
Fastly Fastly
Email: jri.ietf@gmail.com Email: jri.ietf@gmail.com
Martin Thomson (editor) Martin Thomson (editor)
Mozilla Mozilla
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