draft-ietf-quic-transport-07.txt   draft-ietf-quic-transport-08.txt 
QUIC J. Iyengar, Ed. QUIC J. Iyengar, Ed.
Internet-Draft Google Internet-Draft Google
Intended status: Standards Track M. Thomson, Ed. Intended status: Standards Track M. Thomson, Ed.
Expires: April 16, 2018 Mozilla Expires: June 8, 2018 Mozilla
October 13, 2017 December 5, 2017
QUIC: A UDP-Based Multiplexed and Secure Transport QUIC: A UDP-Based Multiplexed and Secure Transport
draft-ietf-quic-transport-07 draft-ietf-quic-transport-08
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
Discussion of this draft takes place on the QUIC working group Discussion of this draft takes place on the QUIC working group
mailing list (quic@ietf.org), which is archived at mailing list (quic@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/search/?email_list=quic [1]. https://mailarchive.ietf.org/arch/search/?email_list=quic [1].
Working Group information can be found at https://github.com/quicwg Working Group information can be found at https://github.com/quicwg
[2]; source code and issues list for this draft can be found at [2]; source code and issues list for this draft can be found at
https://github.com/quicwg/base-drafts/labels/transport [3]. https://github.com/quicwg/base-drafts/labels/-transport [3].
Status of This Memo Status of This Memo
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Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 5 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 5
2.1. Notational Conventions . . . . . . . . . . . . . . . . . 5 2.1. Notational Conventions . . . . . . . . . . . . . . . . . 6
3. A QUIC Overview . . . . . . . . . . . . . . . . . . . . . . . 6 3. A QUIC Overview . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Low-Latency Connection Establishment . . . . . . . . . . 6 3.1. Low-Latency Connection Establishment . . . . . . . . . . 6
3.2. Stream Multiplexing . . . . . . . . . . . . . . . . . . . 6 3.2. Stream Multiplexing . . . . . . . . . . . . . . . . . . . 7
3.3. Rich Signaling for Congestion Control and Loss Recovery . 7 3.3. Rich Signaling for Congestion Control and Loss Recovery . 7
3.4. Stream and Connection Flow Control . . . . . . . . . . . 7 3.4. Stream and Connection Flow Control . . . . . . . . . . . 7
3.5. Authenticated and Encrypted Header and Payload . . . . . 7 3.5. Authenticated and Encrypted Header and Payload . . . . . 8
3.6. Connection Migration and Resilience to NAT Rebinding . . 8 3.6. Connection Migration and Resilience to NAT Rebinding . . 8
3.7. Version Negotiation . . . . . . . . . . . . . . . . . . . 8 3.7. Version Negotiation . . . . . . . . . . . . . . . . . . . 8
4. Versions . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4. Versions . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Packet Types and Formats . . . . . . . . . . . . . . . . . . 9 5. Packet Types and Formats . . . . . . . . . . . . . . . . . . 9
5.1. Long Header . . . . . . . . . . . . . . . . . . . . . . . 9 5.1. Long Header . . . . . . . . . . . . . . . . . . . . . . . 10
5.2. Short Header . . . . . . . . . . . . . . . . . . . . . . 11 5.2. Short Header . . . . . . . . . . . . . . . . . . . . . . 11
5.3. Version Negotiation Packet . . . . . . . . . . . . . . . 13 5.3. Version Negotiation Packet . . . . . . . . . . . . . . . 13
5.4. Cleartext Packets . . . . . . . . . . . . . . . . . . . . 13 5.4. Cryptographic Handshake Packets . . . . . . . . . . . . . 14
5.4.1. Client Initial Packet . . . . . . . . . . . . . . . . 14 5.4.1. Initial Packet . . . . . . . . . . . . . . . . . . . 14
5.4.2. Server Stateless Retry Packet . . . . . . . . . . . . 14 5.4.2. Retry Packet . . . . . . . . . . . . . . . . . . . . 15
5.4.3. Server Cleartext Packet . . . . . . . . . . . . . . . 15 5.4.3. Handshake Packet . . . . . . . . . . . . . . . . . . 15
5.4.4. Client Cleartext Packet . . . . . . . . . . . . . . . 15
5.5. Protected Packets . . . . . . . . . . . . . . . . . . . . 16 5.5. Protected Packets . . . . . . . . . . . . . . . . . . . . 16
5.6. Connection ID . . . . . . . . . . . . . . . . . . . . . . 16 5.6. Connection ID . . . . . . . . . . . . . . . . . . . . . . 16
5.7. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 17 5.7. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 17
5.7.1. Initial Packet Number . . . . . . . . . . . . . . . . 18 5.7.1. Initial Packet Number . . . . . . . . . . . . . . . . 18
5.8. Handling Packets from Different Versions . . . . . . . . 18 5.8. Handling Packets from Different Versions . . . . . . . . 18
6. Frames and Frame Types . . . . . . . . . . . . . . . . . . . 19 6. Frames and Frame Types . . . . . . . . . . . . . . . . . . . 19
7. Life of a Connection . . . . . . . . . . . . . . . . . . . . 20 7. Life of a Connection . . . . . . . . . . . . . . . . . . . . 20
7.1. Matching Packets to Connections . . . . . . . . . . . . . 21 7.1. Matching Packets to Connections . . . . . . . . . . . . . 21
7.2. Version Negotiation . . . . . . . . . . . . . . . . . . . 22 7.2. Version Negotiation . . . . . . . . . . . . . . . . . . . 22
7.2.1. Sending Version Negotiation Packets . . . . . . . . . 22 7.2.1. Sending Version Negotiation Packets . . . . . . . . . 22
7.2.2. Handling Version Negotiation Packets . . . . . . . . 23 7.2.2. Handling Version Negotiation Packets . . . . . . . . 23
7.2.3. Using Reserved Versions . . . . . . . . . . . . . . . 23 7.2.3. Using Reserved Versions . . . . . . . . . . . . . . . 23
7.3. Cryptographic and Transport Handshake . . . . . . . . . . 24 7.3. Cryptographic and Transport Handshake . . . . . . . . . . 24
7.4. Transport Parameters . . . . . . . . . . . . . . . . . . 25 7.4. Transport Parameters . . . . . . . . . . . . . . . . . . 25
7.4.1. Transport Parameter Definitions . . . . . . . . . . . 27 7.4.1. Transport Parameter Definitions . . . . . . . . . . . 27
7.4.2. Values of Transport Parameters for 0-RTT . . . . . . 28 7.4.2. Values of Transport Parameters for 0-RTT . . . . . . 29
7.4.3. New Transport Parameters . . . . . . . . . . . . . . 28 7.4.3. New Transport Parameters . . . . . . . . . . . . . . 29
7.4.4. Version Negotiation Validation . . . . . . . . . . . 29 7.4.4. Version Negotiation Validation . . . . . . . . . . . 29
7.5. Stateless Retries . . . . . . . . . . . . . . . . . . . . 30 7.5. Stateless Retries . . . . . . . . . . . . . . . . . . . . 31
7.6. Proof of Source Address Ownership . . . . . . . . . . . . 31 7.6. Proof of Source Address Ownership . . . . . . . . . . . . 31
7.6.1. Client Address Validation Procedure . . . . . . . . . 31 7.6.1. Client Address Validation Procedure . . . . . . . . . 32
7.6.2. Address Validation on Session Resumption . . . . . . 32 7.6.2. Address Validation on Session Resumption . . . . . . 33
7.6.3. Address Validation Token Integrity . . . . . . . . . 33 7.6.3. Address Validation Token Integrity . . . . . . . . . 34
7.7. Connection Migration . . . . . . . . . . . . . . . . . . 33 7.7. Connection Migration . . . . . . . . . . . . . . . . . . 34
7.7.1. Privacy Implications of Connection Migration . . . . 33 7.7.1. Privacy Implications of Connection Migration . . . . 35
7.7.2. Address Validation for Migrated Connections . . . . . 35 7.7.2. Address Validation for Migrated Connections . . . . . 36
7.8. Connection Termination . . . . . . . . . . . . . . . . . 35 7.8. Spurious Connection Migrations . . . . . . . . . . . . . 37
7.8.1. Draining Period . . . . . . . . . . . . . . . . . . . 35 7.9. Connection Termination . . . . . . . . . . . . . . . . . 38
7.8.2. Idle Timeout . . . . . . . . . . . . . . . . . . . . 35 7.9.1. Closing and Draining Connection States . . . . . . . 38
7.8.3. Immediate Close . . . . . . . . . . . . . . . . . . . 36 7.9.2. Idle Timeout . . . . . . . . . . . . . . . . . . . . 40
7.8.4. Stateless Reset . . . . . . . . . . . . . . . . . . . 36 7.9.3. Immediate Close . . . . . . . . . . . . . . . . . . . 40
8. Frame Types and Formats . . . . . . . . . . . . . . . . . . . 39 7.9.4. Stateless Reset . . . . . . . . . . . . . . . . . . . 41
8.1. PADDING Frame . . . . . . . . . . . . . . . . . . . . . . 39 8. Frame Types and Formats . . . . . . . . . . . . . . . . . . . 43
8.2. RST_STREAM Frame . . . . . . . . . . . . . . . . . . . . 39 8.1. Variable-Length Integer Encoding . . . . . . . . . . . . 44
8.3. CONNECTION_CLOSE frame . . . . . . . . . . . . . . . . . 40 8.2. PADDING Frame . . . . . . . . . . . . . . . . . . . . . . 44
8.4. APPLICATION_CLOSE frame . . . . . . . . . . . . . . . . . 41 8.3. RST_STREAM Frame . . . . . . . . . . . . . . . . . . . . 45
8.5. MAX_DATA Frame . . . . . . . . . . . . . . . . . . . . . 41 8.4. CONNECTION_CLOSE frame . . . . . . . . . . . . . . . . . 45
8.6. MAX_STREAM_DATA Frame . . . . . . . . . . . . . . . . . . 42 8.5. APPLICATION_CLOSE frame . . . . . . . . . . . . . . . . . 46
8.7. MAX_STREAM_ID Frame . . . . . . . . . . . . . . . . . . . 43 8.6. MAX_DATA Frame . . . . . . . . . . . . . . . . . . . . . 46
8.8. PING frame . . . . . . . . . . . . . . . . . . . . . . . 43 8.7. MAX_STREAM_DATA Frame . . . . . . . . . . . . . . . . . . 47
8.9. BLOCKED Frame . . . . . . . . . . . . . . . . . . . . . . 44 8.8. MAX_STREAM_ID Frame . . . . . . . . . . . . . . . . . . . 48
8.10. STREAM_BLOCKED Frame . . . . . . . . . . . . . . . . . . 44 8.9. PING Frame . . . . . . . . . . . . . . . . . . . . . . . 49
8.11. STREAM_ID_BLOCKED Frame . . . . . . . . . . . . . . . . . 44 8.10. BLOCKED Frame . . . . . . . . . . . . . . . . . . . . . . 50
8.12. NEW_CONNECTION_ID Frame . . . . . . . . . . . . . . . . . 45 8.11. STREAM_BLOCKED Frame . . . . . . . . . . . . . . . . . . 50
8.13. STOP_SENDING Frame . . . . . . . . . . . . . . . . . . . 45 8.12. STREAM_ID_BLOCKED Frame . . . . . . . . . . . . . . . . . 51
8.14. ACK Frame . . . . . . . . . . . . . . . . . . . . . . . . 46 8.13. NEW_CONNECTION_ID Frame . . . . . . . . . . . . . . . . . 51
8.14.1. ACK Block Section . . . . . . . . . . . . . . . . . 48 8.14. STOP_SENDING Frame . . . . . . . . . . . . . . . . . . . 52
8.14.2. ACK Frames and Packet Protection . . . . . . . . . . 50 8.15. PONG Frame . . . . . . . . . . . . . . . . . . . . . . . 52
8.15. STREAM Frame . . . . . . . . . . . . . . . . . . . . . . 51 8.16. ACK Frame . . . . . . . . . . . . . . . . . . . . . . . . 53
9. Packetization and Reliability . . . . . . . . . . . . . . . . 52 8.16.1. ACK Block Section . . . . . . . . . . . . . . . . . 54
9.1. Special Considerations for PMTU Discovery . . . . . . . . 55 8.16.2. Sending ACK Frames . . . . . . . . . . . . . . . . . 56
10. Streams: QUIC's Data Structuring Abstraction . . . . . . . . 55 8.16.3. ACK Frames and Packet Protection . . . . . . . . . . 57
10.1. Stream Identifiers . . . . . . . . . . . . . . . . . . . 56 8.17. STREAM Frames . . . . . . . . . . . . . . . . . . . . . . 58
10.2. Life of a Stream . . . . . . . . . . . . . . . . . . . . 56 9. Packetization and Reliability . . . . . . . . . . . . . . . . 59
10.2.1. idle . . . . . . . . . . . . . . . . . . . . . . . . 58 9.1. Special Considerations for PMTU Discovery . . . . . . . . 62
10.2.2. open . . . . . . . . . . . . . . . . . . . . . . . . 58 10. Streams: QUIC's Data Structuring Abstraction . . . . . . . . 62
10.2.3. half-closed (local) . . . . . . . . . . . . . . . . 59 10.1. Stream Identifiers . . . . . . . . . . . . . . . . . . . 63
10.2.4. half-closed (remote) . . . . . . . . . . . . . . . . 59 10.2. Stream States . . . . . . . . . . . . . . . . . . . . . 64
10.2.5. closed . . . . . . . . . . . . . . . . . . . . . . . 60 10.2.1. Send Stream States . . . . . . . . . . . . . . . . . 65
10.3. Solicited State Transitions . . . . . . . . . . . . . . 60 10.2.2. Receive Stream States . . . . . . . . . . . . . . . 67
10.4. Stream Concurrency . . . . . . . . . . . . . . . . . . . 61 10.2.3. Permitted Frame Types . . . . . . . . . . . . . . . 70
10.5. Sending and Receiving Data . . . . . . . . . . . . . . . 62 10.2.4. Bidirectional Stream States . . . . . . . . . . . . 70
10.6. Stream Prioritization . . . . . . . . . . . . . . . . . 62 10.3. Solicited State Transitions . . . . . . . . . . . . . . 71
11. Flow Control . . . . . . . . . . . . . . . . . . . . . . . . 63 10.4. Stream Concurrency . . . . . . . . . . . . . . . . . . . 72
11.1. Edge Cases and Other Considerations . . . . . . . . . . 64 10.5. Sending and Receiving Data . . . . . . . . . . . . . . . 73
11.1.1. Response to a RST_STREAM . . . . . . . . . . . . . . 65 10.6. Stream Prioritization . . . . . . . . . . . . . . . . . 73
11.1.2. Data Limit Increments . . . . . . . . . . . . . . . 65 11. Flow Control . . . . . . . . . . . . . . . . . . . . . . . . 74
11.2. Stream Limit Increment . . . . . . . . . . . . . . . . . 66 11.1. Edge Cases and Other Considerations . . . . . . . . . . 75
11.2.1. Blocking on Flow Control . . . . . . . . . . . . . . 66 11.1.1. Response to a RST_STREAM . . . . . . . . . . . . . . 76
11.3. Stream Final Offset . . . . . . . . . . . . . . . . . . 66 11.1.2. Data Limit Increments . . . . . . . . . . . . . . . 76
12. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 67 11.2. Stream Limit Increment . . . . . . . . . . . . . . . . . 77
12.1. Connection Errors . . . . . . . . . . . . . . . . . . . 67 11.2.1. Blocking on Flow Control . . . . . . . . . . . . . . 77
12.2. Stream Errors . . . . . . . . . . . . . . . . . . . . . 68 11.3. Stream Final Offset . . . . . . . . . . . . . . . . . . 77
12.3. Transport Error Codes . . . . . . . . . . . . . . . . . 68 12. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 78
12.4. Application Protocol Error Codes . . . . . . . . . . . . 70 12.1. Connection Errors . . . . . . . . . . . . . . . . . . . 78
13. Security and Privacy Considerations . . . . . . . . . . . . . 70 12.2. Stream Errors . . . . . . . . . . . . . . . . . . . . . 79
13.1. Spoofed ACK Attack . . . . . . . . . . . . . . . . . . . 70 12.3. Transport Error Codes . . . . . . . . . . . . . . . . . 79
13.2. Slowloris Attacks . . . . . . . . . . . . . . . . . . . 70 12.4. Application Protocol Error Codes . . . . . . . . . . . . 81
13.3. Stream Fragmentation and Reassembly Attacks . . . . . . 71 13. Security and Privacy Considerations . . . . . . . . . . . . . 81
13.4. Stream Commitment Attack . . . . . . . . . . . . . . . . 71 13.1. Spoofed ACK Attack . . . . . . . . . . . . . . . . . . . 81
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 72 13.2. Slowloris Attacks . . . . . . . . . . . . . . . . . . . 82
14.1. QUIC Transport Parameter Registry . . . . . . . . . . . 72 13.3. Stream Fragmentation and Reassembly Attacks . . . . . . 82
14.2. QUIC Transport Error Codes Registry . . . . . . . . . . 73 13.4. Stream Commitment Attack . . . . . . . . . . . . . . . . 82
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 75 14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 83
15.1. Normative References . . . . . . . . . . . . . . . . . . 75 14.1. QUIC Transport Parameter Registry . . . . . . . . . . . 83
15.2. Informative References . . . . . . . . . . . . . . . . . 76 14.2. QUIC Transport Error Codes Registry . . . . . . . . . . 84
15.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 77 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 87
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 77 15.1. Normative References . . . . . . . . . . . . . . . . . . 87
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 77 15.2. Informative References . . . . . . . . . . . . . . . . . 88
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 78 15.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 89
C.1. Since draft-ietf-quic-transport-06 . . . . . . . . . . . 78 Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 89
C.2. Since draft-ietf-quic-transport-05 . . . . . . . . . . . 78 Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 89
C.3. Since draft-ietf-quic-transport-04 . . . . . . . . . . . 78 Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 90
C.4. Since draft-ietf-quic-transport-03 . . . . . . . . . . . 79 C.1. Since draft-ietf-quic-transport-07 . . . . . . . . . . . 90
C.5. Since draft-ietf-quic-transport-02 . . . . . . . . . . . 79 C.2. Since draft-ietf-quic-transport-06 . . . . . . . . . . . 90
C.6. Since draft-ietf-quic-transport-01 . . . . . . . . . . . 80 C.3. Since draft-ietf-quic-transport-05 . . . . . . . . . . . 90
C.7. Since draft-ietf-quic-transport-00 . . . . . . . . . . . 82 C.4. Since draft-ietf-quic-transport-04 . . . . . . . . . . . 91
C.8. Since draft-hamilton-quic-transport-protocol-01 . . . . . 82 C.5. Since draft-ietf-quic-transport-03 . . . . . . . . . . . 91
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 82 C.6. Since draft-ietf-quic-transport-02 . . . . . . . . . . . 91
C.7. Since draft-ietf-quic-transport-01 . . . . . . . . . . . 92
C.8. Since draft-ietf-quic-transport-00 . . . . . . . . . . . 94
C.9. Since draft-hamilton-quic-transport-protocol-01 . . . . . 95
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 95
1. Introduction 1. Introduction
QUIC is a multiplexed and secure transport protocol that runs on top QUIC is a multiplexed and secure transport protocol that runs on top
of UDP. QUIC aims to provide a flexible set of features that allow of UDP. QUIC aims to provide a flexible set of features that allow
it to be a general-purpose transport for multiple applications. it to be a general-purpose transport for multiple applications.
QUIC implements techniques learned from experience with TCP, SCTP and QUIC implements techniques learned from experience with TCP, SCTP and
other transport protocols. QUIC uses UDP as substrate so as to not other transport protocols. QUIC uses UDP as substrate so as to not
require changes to legacy client operating systems and middleboxes to require changes to legacy client operating systems and middleboxes to
skipping to change at page 5, line 22 skipping to change at page 5, line 28
including the conceptual design, wire format, and mechanisms of the including the conceptual design, wire format, and mechanisms of the
QUIC protocol for connection establishment, stream multiplexing, QUIC protocol for connection establishment, stream multiplexing,
stream and connection-level flow control, and data reliability. stream and connection-level flow control, and data reliability.
Accompanying documents describe QUIC's loss detection and congestion Accompanying documents describe QUIC's loss detection and congestion
control [QUIC-RECOVERY], and the use of TLS 1.3 for key negotiation control [QUIC-RECOVERY], and the use of TLS 1.3 for key negotiation
[QUIC-TLS]. [QUIC-TLS].
2. Conventions and Definitions 2. Conventions and Definitions
The words "MUST", "MUST NOT", "SHOULD", and "MAY" are used in this The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
document. It's not shouting; when they are capitalized, they have "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
the special meaning defined in [RFC2119]. "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Definitions of terms that are used in this document: Definitions of terms that are used in this document:
Client: The endpoint initiating a QUIC connection. Client: The endpoint initiating a QUIC connection.
Server: The endpoint accepting incoming QUIC connections. Server: The endpoint accepting incoming QUIC connections.
Endpoint: The client or server end of a connection. Endpoint: The client or server end of a connection.
Stream: A logical, bi-directional channel of ordered bytes within a Stream: A logical, bi-directional channel of ordered bytes within a
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QUIC packet: A well-formed UDP payload that can be parsed by a QUIC QUIC packet: A well-formed UDP payload that can be parsed by a QUIC
receiver. QUIC packet size in this document refers to the UDP receiver. QUIC packet size in this document refers to the UDP
payload size. payload size.
2.1. Notational Conventions 2.1. Notational Conventions
Packet and frame diagrams use the format described in Section 3.1 of Packet and frame diagrams use the format described in Section 3.1 of
[RFC2360], with the following additional conventions: [RFC2360], with the following additional conventions:
[x] Indicates that x is optional [x] Indicates that x is optional
{x} Indicates that x is encrypted {x} Indicates that x is encrypted
x (A) Indicates that x is A bits long x (A) Indicates that x is A bits long
x (A/B/C) ... Indicates that x is one of A, B, or C bits long x (A/B/C) ... Indicates that x is one of A, B, or C bits long
x (i) ... Indicates that x uses the variable-length encoding in
Section 8.1
x (*) ... Indicates that x is variable-length x (*) ... Indicates that x is variable-length
3. A QUIC Overview 3. A QUIC Overview
This section briefly describes QUIC's key mechanisms and benefits. This section briefly describes QUIC's key mechanisms and benefits.
Key strengths of QUIC include: Key strengths of QUIC include:
o Low-latency connection establishment o Low-latency connection establishment
o Multiplexing without head-of-line blocking o Multiplexing without head-of-line blocking
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QUIC's packet framing and acknowledgments carry rich information that QUIC's packet framing and acknowledgments carry rich information that
help both congestion control and loss recovery in fundamental ways. help both congestion control and loss recovery in fundamental ways.
Each QUIC packet carries a new packet number, including those Each QUIC packet carries a new packet number, including those
carrying retransmitted data. This obviates the need for a separate carrying retransmitted data. This obviates the need for a separate
mechanism to distinguish acknowledgments for retransmissions from mechanism to distinguish acknowledgments for retransmissions from
those for original transmissions, avoiding TCP's retransmission those for original transmissions, avoiding TCP's retransmission
ambiguity problem. QUIC acknowledgments also explicitly encode the ambiguity problem. QUIC acknowledgments also explicitly encode the
delay between the receipt of a packet and its acknowledgment being delay between the receipt of a packet and its acknowledgment being
sent, and together with the monotonically-increasing packet numbers, sent, and together with the monotonically-increasing packet numbers,
this allows for precise network roundtrip-time (RTT) calculation. this allows for precise network roundtrip-time (RTT) calculation.
QUIC's ACK frames support up to 256 ACK blocks, so QUIC is more QUIC's ACK frames support multiple ACK blocks, so QUIC is more
resilient to reordering than TCP with SACK support, as well as able resilient to reordering than TCP with SACK support, as well as able
to keep more bytes on the wire when there is reordering or loss. to keep more bytes on the wire when there is reordering or loss.
3.4. Stream and Connection Flow Control 3.4. Stream and Connection Flow Control
QUIC implements stream- and connection-level flow control. At a high QUIC implements stream- and connection-level flow control. At a high
level, a QUIC receiver advertises the maximum amount of data that it level, a QUIC receiver advertises the maximum amount of data that it
is willing to receive on each stream. As data is sent, received, and is willing to receive on each stream. As data is sent, received, and
delivered on a particular stream, the receiver sends MAX_STREAM_DATA delivered on a particular stream, the receiver sends MAX_STREAM_DATA
frames that increase the advertised limit for that stream, allowing frames that increase the advertised limit for that stream, allowing
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not encrypted, but information sent in these unencrypted handshake not encrypted, but information sent in these unencrypted handshake
packets is later verified as part of cryptographic processing. packets is later verified as part of cryptographic processing.
3.6. Connection Migration and Resilience to NAT Rebinding 3.6. Connection Migration and Resilience to NAT Rebinding
QUIC connections are identified by a Connection ID, a 64-bit unsigned QUIC connections are identified by a Connection ID, a 64-bit unsigned
number randomly generated by the server. QUIC's consistent number randomly generated by the server. QUIC's consistent
connection ID allows connections to survive changes to the client's connection ID allows connections to survive changes to the client's
IP and port, such as those caused by NAT rebindings or by the client IP and port, such as those caused by NAT rebindings or by the client
changing network connectivity to a new address. QUIC provides changing network connectivity to a new address. QUIC provides
automatic cryptographic verification of a rebound lient, since the automatic cryptographic verification of a rebound client, since the
client continues to use the same session key for encrypting and client continues to use the same session key for encrypting and
decrypting packets. The consistent connection ID can be used to decrypting packets. The consistent connection ID can be used to
allow migration of the connection to a new server IP address as well, allow migration of the connection to a new server IP address as well,
since the Connection ID remains consistent across changes in the since the Connection ID remains consistent across changes in the
client's and the server's network addresses. client's and the server's network addresses.
3.7. Version Negotiation 3.7. Version Negotiation
QUIC version negotiation allows for multiple versions of the protocol QUIC version negotiation allows for multiple versions of the protocol
to be deployed and used concurrently. Version negotiation is to be deployed and used concurrently. Version negotiation is
described in Section 7.2. described in Section 7.2.
4. Versions 4. Versions
QUIC versions are identified using a 32-bit unsigned number. QUIC versions are identified using a 32-bit unsigned number.
The version 0x00000000 is reserved to represent an invalid version. The version 0x00000000 is reserved to represent version negotiation.
This version of the specification is identified by the number This version of the specification is identified by the number
0x00000001. 0x00000001.
Version 0x00000001 of QUIC uses TLS as a cryptographic handshake Version 0x00000001 of QUIC uses TLS as a cryptographic handshake
protocol, as described in [QUIC-TLS]. protocol, as described in [QUIC-TLS].
Versions with the most significant 16 bits of the version number Versions with the most significant 16 bits of the version number
cleared are reserved for use in future IETF consensus documents. cleared are reserved for use in future IETF consensus documents.
Versions that follow the pattern 0x?a?a?a?a are reserved for use in Versions that follow the pattern 0x?a?a?a?a are reserved for use in
skipping to change at page 10, line 4 skipping to change at page 10, line 9
bits of fields, the least significant bit is referred to as bit 0. bits of fields, the least significant bit is referred to as bit 0.
Hexadecimal notation is used for describing the value of fields. Hexadecimal notation is used for describing the value of fields.
Any QUIC packet has either a long or a short header, as indicated by Any QUIC packet has either a long or a short header, as indicated by
the Header Form bit. Long headers are expected to be used early in the Header Form bit. Long headers are expected to be used early in
the connection before version negotiation and establishment of 1-RTT the connection before version negotiation and establishment of 1-RTT
keys. Short headers are minimal version-specific headers, which are keys. Short headers are minimal version-specific headers, which are
used after version negotiation and 1-RTT keys are established. used after version negotiation and 1-RTT keys are established.
5.1. Long Header 5.1. Long Header
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|1| Type (7) | |1| Type (7) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Connection ID (64) + + Connection ID (64) +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packet Number (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version (32) | | Version (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packet Number (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload (*) ... | Payload (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Long Header Format Figure 1: Long Header Format
Long headers are used for packets that are sent prior to the Long headers are used for packets that are sent prior to the
completion of version negotiation and establishment of 1-RTT keys. completion of version negotiation and establishment of 1-RTT keys.
Once both conditions are met, a sender switches to sending packets Once both conditions are met, a sender switches to sending packets
using the short header (Section 5.2). The long form allows for using the short header (Section 5.2). The long form allows for
special packets - such as the Version Negotiation packet - to be special packets - such as the Version Negotiation packet - to be
skipping to change at page 10, line 40 skipping to change at page 10, line 46
Header Form: The most significant bit (0x80) of octet 0 (the first Header Form: The most significant bit (0x80) of octet 0 (the first
octet) is set to 1 for long headers. octet) is set to 1 for long headers.
Long Packet Type: The remaining seven bits of octet 0 contain the Long Packet Type: The remaining seven bits of octet 0 contain the
packet type. This field can indicate one of 128 packet types. packet type. This field can indicate one of 128 packet types.
The types specified for this version are listed in Table 1. The types specified for this version are listed in Table 1.
Connection ID: Octets 1 through 8 contain the connection ID. Connection ID: Octets 1 through 8 contain the connection ID.
Section 5.6 describes the use of this field in more detail. Section 5.6 describes the use of this field in more detail.
Packet Number: Octets 9 to 12 contain the packet number. Version: Octets 9 to 12 contain the selected protocol version. This
Section 5.7 describes the use of packet numbers. field indicates which version of QUIC is in use and determines how
the rest of the protocol fields are interpreted.
Version: Octets 13 to 16 contain the selected protocol version. Packet Number: Octets 13 to 16 contain the packet number.
This field indicates which version of QUIC is in use and Section 5.7 describes the use of packet numbers.
determines how the rest of the protocol fields are interpreted.
Payload: Octets from 17 onwards (the rest of QUIC packet) are the Payload: Octets from 17 onwards (the rest of QUIC packet) are the
payload of the packet. payload of the packet.
The following packet types are defined: The following packet types are defined:
+------+------------------------+---------------+ +------+-----------------+---------------+
| Type | Name | Section | | Type | Name | Section |
+------+------------------------+---------------+ +------+-----------------+---------------+
| 0x01 | Version Negotiation | Section 5.3 | | 0x7F | Initial | Section 5.4.1 |
| | | | | | | |
| 0x02 | Client Initial | Section 5.4.1 | | 0x7E | Retry | Section 5.4.2 |
| | | | | | | |
| 0x03 | Server Stateless Retry | Section 5.4.2 | | 0x7D | Handshake | Section 5.4.3 |
| | | | | | | |
| 0x04 | Server Cleartext | Section 5.4.3 | | 0x7C | 0-RTT Protected | Section 5.5 |
| | | | +------+-----------------+---------------+
| 0x05 | Client Cleartext | Section 5.4.4 |
| | | |
| 0x06 | 0-RTT Protected | Section 5.5 |
+------+------------------------+---------------+
Table 1: Long Header Packet Types Table 1: Long Header Packet Types
The header form, packet type, connection ID, packet number and The header form, packet type, connection ID, packet number and
version fields of a long header packet are version-independent. The version fields of a long header packet are version-independent. The
types of packets defined in Table 1 are version-specific. See types of packets defined in Table 1 are version-specific. See
Section 5.8 for details on how packets from different versions of Section 5.8 for details on how packets from different versions of
QUIC are interpreted. QUIC are interpreted.
The interpretation of the fields and the payload are specific to a The interpretation of the fields and the payload are specific to a
skipping to change at page 12, line 8 skipping to change at page 12, line 11
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Short Header Format Figure 2: Short Header Format
The short header can be used after the version and 1-RTT keys are The short header can be used after the version and 1-RTT keys are
negotiated. This header form has the following fields: negotiated. This header form has the following fields:
Header Form: The most significant bit (0x80) of octet 0 is set to 0 Header Form: The most significant bit (0x80) of octet 0 is set to 0
for the short header. for the short header.
Connection ID Flag: The second bit (0x40) of octet 0 indicates Omit Connection ID Flag: The second bit (0x40) of octet 0 indicates
whether the Connection ID field is present. If set to 1, then the whether the Connection ID field is omitted. If set to 0, then the
Connection ID field is present; if set to 0, the Connection ID Connection ID field is present; if set to 1, the Connection ID
field is omitted. The Connection ID field can only be omitted if field is omitted. The Connection ID field can only be omitted if
the omit_connection_id transport parameter (Section 7.4.1) is the omit_connection_id transport parameter (Section 7.4.1) is
specified by the intended recipient of the packet. specified by the intended recipient of the packet.
Key Phase Bit: The third bit (0x20) of octet 0 indicates the key Key Phase Bit: The third bit (0x20) of octet 0 indicates the key
phase, which allows a recipient of a packet to identify the packet phase, which allows a recipient of a packet to identify the packet
protection keys that are used to protect the packet. See protection keys that are used to protect the packet. See
[QUIC-TLS] for details. [QUIC-TLS] for details.
Short Packet Type: The remaining 5 bits of octet 0 include one of 32 Short Packet Type: The remaining 5 bits of octet 0 include one of 32
packet types. Table 2 lists the types that are defined for short packet types. Table 2 lists the types that are defined for short
packets. packets.
Connection ID: If the Connection ID Flag is set, a connection ID Connection ID: If the Omit Connection ID Flag is not set, a
occupies octets 1 through 8 of the packet. See Section 5.6 for connection ID occupies octets 1 through 8 of the packet. See
more details. Section 5.6 for more details.
Packet Number: The length of the packet number field depends on the Packet Number: The length of the packet number field depends on the
packet type. This field can be 1, 2 or 4 octets long depending on packet type. This field can be 1, 2 or 4 octets long depending on
the short packet type. the short packet type.
Protected Payload: Packets with a short header always include a Protected Payload: Packets with a short header always include a
1-RTT protected payload. 1-RTT protected payload.
The packet type in a short header currently determines only the size The packet type in a short header currently determines only the size
of the packet number field. Additional types can be used to signal of the packet number field. Additional types can be used to signal
the presence of other fields. the presence of other fields.
+------+--------------------+ +------+--------------------+
| Type | Packet Number Size | | Type | Packet Number Size |
+------+--------------------+ +------+--------------------+
| 0x01 | 1 octet | | 0x1F | 1 octet |
| | | | | |
| 0x02 | 2 octets | | 0x1E | 2 octets |
| | | | | |
| 0x03 | 4 octets | | 0x1D | 4 octets |
+------+--------------------+ +------+--------------------+
Table 2: Short Header Packet Types Table 2: Short Header Packet Types
The header form, connection ID flag and connection ID of a short The header form, omit connection ID flag, and connection ID of a
header packet are version-independent. The remaining fields are short header packet are version-independent. The remaining fields
specific to the selected QUIC version. See Section 5.8 for details are specific to the selected QUIC version. See Section 5.8 for
on how packets from different versions of QUIC are interpreted. details on how packets from different versions of QUIC are
interpreted.
5.3. Version Negotiation Packet 5.3. Version Negotiation Packet
A Version Negotiation packet has long headers with a type value of A Version Negotiation packet is inherently not version-specific, and
0x01 and is sent only by servers. The Version Negotiation packet is does not use the packet headers defined above. Upon receipt by a
a response to a client packet that contains a version that is not client, it will appear to be a packet using the long header, but will
supported by the server. be identified as a Version Negotiation packet based on the Version
field.
The packet number, connection ID and version fields echo
corresponding values from the triggering client packet. This allows
clients some assurance that the server received the packet and that
the Version Negotiation packet was not carried in a packet with a
spoofed source address.
A Version Negotiation packet is never explicitly acknowledged in an The Version Negotiation packet is a response to a client packet that
ACK frame by a client. Receiving another Client Initial packet contains a version that is not supported by the server, and is only
implicitly acknowledges a Version Negotiation packet. sent by servers.
The payload of the Version Negotiation packet is a list of 32-bit The layout of a Version Negotiation packet is:
versions which the server supports, as shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+
|1| Unused (7) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Connection ID (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Supported Version 1 (32) ... | Supported Version 1 (32) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Supported Version 2 (32)] ... | [Supported Version 2 (32)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Supported Version N (32)] ... | [Supported Version N (32)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Version Negotiation Packet Figure 3: Version Negotiation Packet
The value in the Unused field is selected randomly by the server.
The Connection ID field echoes the corresponding value from the
triggering client packet. This allows clients some assurance that
the server received the packet and that the Version Negotiation
packet is in fact from the server. The Version field MUST be set to
0x00000000. The remainder of the Version Negotiation packet is a
list of 32-bit versions which the server supports.
A Version Negotiation packet cannot be explicitly acknowledged in an
ACK frame by a client. Receiving another Initial packet implicitly
acknowledges a Version Negotiation packet.
See Section 7.2 for a description of the version negotiation process. See Section 7.2 for a description of the version negotiation process.
5.4. Cleartext Packets 5.4. Cryptographic Handshake Packets
Cleartext packets are sent during the handshake prior to key Once version negotiation is complete, the cryptographic handshake is
negotiation. used to agree on cryptographic keys. The cryptographic handshake is
carried in Initial (Section 5.4.1), Retry (Section 5.4.2) and
Handshake (Section 5.4.3) packets.
All cleartext packets contain the current QUIC version in the version All these packets use the long header and contain the current QUIC
field. version in the version field.
In order to prevent tampering by version-unaware middleboxes, In order to prevent tampering by version-unaware middleboxes,
Cleartext packets are protected with a connection and version handshake packets are protected with a connection- and version-
specific key, as described in [QUIC-TLS]. This protection does not specific key, as described in [QUIC-TLS]. This protection does not
provide confidentiality or integrity against on-path attackers, but provide confidentiality or integrity against on-path attackers, but
provides some level of protection against off-path attackers. provides some level of protection against off-path attackers.
5.4.1. Client Initial Packet 5.4.1. Initial Packet
The Client Initial packet uses long headers with a type value of The Initial packet uses long headers with a type value of 0x7E. It
0x02. It carries the first cryptographic handshake message sent by carries the first cryptographic handshake message sent by the client.
the client.
The client populates the connection ID field with randomly selected The client populates the connection ID field with randomly selected
values, unless it has received a packet from the server. If the values, unless it has received a packet from the server. If the
client has received a packet from the server, the connection ID field client has received a packet from the server, the connection ID field
uses the value provided by the server. uses the value provided by the server.
The first Client Initial packet that is sent by a client contains a The first Initial packet that is sent by a client contains a
random 31-bit value. All subsequent packets contain a packet number randomized packet number. All subsequent packets contain a packet
that is incremented by one, see (Section 5.7). number that is incremented by one, see (Section 5.7).
The payload of a Client Initial packet consists of a STREAM frame (or The payload of a Initial packet consists of a STREAM frame (or
frames) for stream 0 containing a cryptographic handshake message, frames) for stream 0 containing a cryptographic handshake message,
with enough PADDING frames that the packet is at least 1200 octets with enough PADDING frames that the packet is at least 1200 octets
(see Section 9). The stream in this packet always starts at an (see Section 9). The stream in this packet always starts at an
offset of 0 (see Section 7.5) and the complete cryptographic offset of 0 (see Section 7.5) and the complete cryptographic
handshake message MUST fit in a single packet (see Section 7.3). handshake message MUST fit in a single packet (see Section 7.3).
The client uses the Client Initial Packet type for any packet that The client uses the Initial packet type for any packet that contains
contains an initial cryptographic handshake message. This includes an initial cryptographic handshake message. This includes all cases
all cases where a new packet containing the initial cryptographic where a new packet containing the initial cryptographic message needs
message needs to be created, this includes the packets sent after to be created, this includes the packets sent after receiving a
receiving a Version Negotiation (Section 5.3) or Server Stateless Version Negotiation (Section 5.3) or Retry packet (Section 5.4.2).
Retry packet (Section 5.4.2).
5.4.2. Server Stateless Retry Packet 5.4.2. Retry Packet
A Server Stateless Retry packet uses long headers with a type value A Retry packet uses long headers with a type value of 0x7D. It
of 0x03. It carries cryptographic handshake messages and carries cryptographic handshake messages and acknowledgments. It is
acknowledgments. It is used by a server that wishes to perform a used by a server that wishes to perform a stateless retry (see
stateless retry (see Section 7.5). Section 7.5).
The packet number and connection ID fields echo the corresponding The packet number and connection ID fields echo the corresponding
fields from the triggering client packet. This allows a client to fields from the triggering client packet. This allows a client to
verify that the server received its packet. verify that the server received its packet.
A Server Stateless Retry packet is never explicitly acknowledged in A Retry packet is never explicitly acknowledged in an ACK frame by a
an ACK frame by a client. Receiving another Client Initial packet client. Receiving another Initial packet implicitly acknowledges a
implicitly acknowledges a Server Stateless Retry packet. Retry packet.
After receiving a Server Stateless Retry packet, the client uses a After receiving a Retry packet, the client uses a new Initial packet
new Client Initial packet containing the next cryptographic handshake containing the next cryptographic handshake message. The client
message. The client retains the state of its cryptographic retains the state of its cryptographic handshake, but discards all
handshake, but discards all transport state. The Client Initial transport state. The Initial packet that is generated in response to
packet that is generated in response to a Server Stateless Retry a Retry packet includes STREAM frames on stream 0 that start again at
packet includes STREAM frames on stream 0 that start again at an an offset of 0.
offset of 0.
Continuing the cryptographic handshake is necessary to ensure that an Continuing the cryptographic handshake is necessary to ensure that an
attacker cannot force a downgrade of any cryptographic parameters. attacker cannot force a downgrade of any cryptographic parameters.
In addition to continuing the cryptographic handshake, the client In addition to continuing the cryptographic handshake, the client
MUST remember the results of any version negotiation that occurred MUST remember the results of any version negotiation that occurred
(see Section 7.2). The client MAY also retain any observed RTT or (see Section 7.2). The client MAY also retain any observed RTT or
congestion state that it has accumulated for the flow, but other congestion state that it has accumulated for the flow, but other
transport state MUST be discarded. transport state MUST be discarded.
The payload of the Server Stateless Retry packet contains a single The payload of the Retry packet contains a single STREAM frame on
STREAM frame on stream 0 with offset 0 containing the server's stream 0 with offset 0 containing the server's cryptographic
cryptographic stateless retry material. It MUST NOT contain any stateless retry material. It MUST NOT contain any other frames. The
other frames. The next STREAM frame sent by the server will also next STREAM frame sent by the server will also start at stream offset
start at stream offset 0. 0.
5.4.3. Server Cleartext Packet
A Server Cleartext packet uses long headers with a type value of
0x04. It is used to carry acknowledgments and cryptographic
handshake messages from the server.
The connection ID field in a Server Cleartext packet contains a
connection ID that is chosen by the server (see Section 5.6).
The first Server Cleartext packet contains a randomized packet
number. This value is increased for each subsequent packet sent by
the server as described in Section 5.7.
The payload of this packet contains STREAM frames and could contain
PADDING and ACK frames.
5.4.4. Client Cleartext Packet 5.4.3. Handshake Packet
A Client Cleartext packet uses long headers with a type value of A Handshake packet uses long headers with a type value of 0x7C. It
0x05, and is sent when the client has received a Server Cleartext is used to carry acknowledgments and cryptographic handshake messages
packet from the server. from the server and client.
The connection ID field in a Client Cleartext packet contains a The connection ID field in a Handshake packet contains a connection
server-selected connection ID, see Section 5.6. ID that is chosen by the server (see Section 5.6).
The Client Cleartext packet includes a packet number that is one The first Handshake packet sent by a server contains a randomized
higher than the last Client Initial, 0-RTT Protected or Client packet number. This value is increased for each subsequent packet
Cleartext packet that was sent. The packet number is incremented for sent by the server as described in Section 5.7. The client
each subsequent packet, see Section 5.7. increments the packet number from its previous packet by one for each
Handshake packet that it sends (which might be an Initial, 0-RTT
Protected, or Handshake packet).
The payload of this packet contains STREAM frames and could contain The payload of this packet contains STREAM frames and could contain
PADDING and ACK frames. PADDING and ACK frames.
5.5. Protected Packets 5.5. Protected Packets
Packets that are protected with 0-RTT keys are sent with long Packets that are protected with 0-RTT keys are sent with long
headers; all packets protected with 1-RTT keys are sent with short headers; all packets protected with 1-RTT keys are sent with short
headers. The different packet types explicitly indicate the headers. The different packet types explicitly indicate the
encryption level and therefore the keys that are used to remove encryption level and therefore the keys that are used to remove
packet protection. packet protection.
Packets protected with 0-RTT keys use a type value of 0x06. The Packets protected with 0-RTT keys use a type value of 0x7B. The
connection ID field for a 0-RTT packet is selected by the client. connection ID field for a 0-RTT packet is selected by the client.
The client can send 0-RTT packets after receiving a Server Cleartext The client can send 0-RTT packets after receiving a Handshake packet
packet (Section 5.4.3), if that packet does not complete the (Section 5.4.3), if that packet does not complete the handshake.
handshake. Even if the client receives a different connection ID in Even if the client receives a different connection ID in the
the Server Cleartext packet, it MUST continue to use the connection Handshake packet, it MUST continue to use the connection ID selected
ID selected by the client for 0-RTT packets, see Section 5.6. by the client for 0-RTT packets, see Section 5.6.
The version field for protected packets is the current QUIC version. The version field for protected packets is the current QUIC version.
The packet number field contains a packet number, which increases The packet number field contains a packet number, which increases
with each packet sent, see Section 5.7 for details. with each packet sent, see Section 5.7 for details.
The payload is protected using authenticated encryption. [QUIC-TLS] The payload is protected using authenticated encryption. [QUIC-TLS]
describes packet protection in detail. After decryption, the describes packet protection in detail. After decryption, the
plaintext consists of a sequence of frames, as described in plaintext consists of a sequence of frames, as described in
Section 6. Section 6.
5.6. Connection ID 5.6. Connection ID
QUIC connections are identified by their 64-bit Connection ID. All QUIC connections are identified by their 64-bit Connection ID. All
long headers contain a Connection ID. Short headers indicate the long headers contain a Connection ID. Short headers indicate the
presence of a Connection ID using the CONNECTION_ID flag. When presence of a Connection ID using the Omit Connection ID flag. When
present, the Connection ID is in the same location in all packet present, the Connection ID is in the same location in all packet
headers, making it straightforward for middleboxes, such as load headers, making it straightforward for middleboxes, such as load
balancers, to locate and use it. balancers, to locate and use it.
The client MUST choose a random connection ID and use it in Client The client MUST choose a random connection ID and use it in Initial
Initial packets (Section 5.4.1) and 0-RTT packets (Section 5.5). packets (Section 5.4.1) and 0-RTT packets (Section 5.5).
When the server receives a Client Initial packet and decides to When the server receives a Initial packet and decides to proceed with
proceed with the handshake, it chooses a new value for the connection the handshake, it chooses a new value for the connection ID and sends
ID and sends that in a Server Cleartext packet (Section 5.4.3). The that in a Handshake packet (Section 5.4.3). The server MAY choose to
server MAY choose to use the value that the client initially selects. use the value that the client initially selects.
Once the client receives the connection ID that the server has Once the client receives the connection ID that the server has
chosen, it MUST use it for all subsequent Client Cleartext chosen, it MUST use it for all subsequent Handshake (Section 5.4.3)
(Section 5.4.4) and 1-RTT (Section 5.5) packets but not for 0-RTT and 1-RTT (Section 5.5) packets but not for 0-RTT packets
packets (Section 5.5). (Section 5.5).
Server's Version Negotiation (Section 5.3) and Stateless Retry Server's Version Negotiation (Section 5.3) and Retry (Section 5.4.2)
(Section 5.4.2) packets MUST use connection ID selected by the packets MUST use connection ID selected by the client.
client.
5.7. Packet Numbers 5.7. Packet Numbers
The packet number is a 64-bit unsigned number and is used as part of The packet number is an integer in the range 0 to 2^62-1. The value
a cryptographic nonce for packet encryption. Each endpoint maintains is used in determining the cryptographic nonce for packet encryption.
a separate packet number for sending and receiving. The packet Each endpoint maintains a separate packet number for sending and
number for sending MUST increase by at least one after sending any receiving. The packet number for sending MUST increase by at least
packet, unless otherwise specified (see Section 5.7.1). one after sending any packet, unless otherwise specified (see
Section 5.7.1).
A QUIC endpoint MUST NOT reuse a packet number within the same A QUIC endpoint MUST NOT reuse a packet number within the same
connection (that is, under the same cryptographic keys). If the connection (that is, under the same cryptographic keys). If the
packet number for sending reaches 2^64 - 1, the sender MUST close the packet number for sending reaches 2^62 - 1, the sender MUST close the
connection without sending a CONNECTION_CLOSE frame or any further connection without sending a CONNECTION_CLOSE frame or any further
packets; a server MAY send a Stateless Reset (Section 7.8.4) in packets; a server MAY send a Stateless Reset (Section 7.9.4) in
response to further packets that it receives. response to further packets that it receives.
To reduce the number of bits required to represent the packet number For the packet header, the number of bits required to represent the
over the wire, only the least significant bits of the packet number packet number are reduced by including only the least significant
are transmitted. The actual packet number for each packet is bits of the packet number. The actual packet number for each packet
reconstructed at the receiver based on the largest packet number is reconstructed at the receiver based on the largest packet number
received on a successfully authenticated packet. received on a successfully authenticated packet.
A packet number is decoded by finding the packet number value that is A packet number is decoded by finding the packet number value that is
closest to the next expected packet. The next expected packet is the closest to the next expected packet. The next expected packet is the
highest received packet number plus one. For example, if the highest 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 16-bit value of 0x1f94 will be decoded as then a packet containing a 16-bit value of 0x1f94 will be decoded as
0xaa831f94. 0xaa831f94.
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
skipping to change at page 18, line 20 skipping to change at page 18, line 17
As a result, the size of the packet number encoding is at least one As a result, the size of the packet number encoding is at least one
more than the base 2 logarithm of the number of contiguous more than the base 2 logarithm of the number of contiguous
unacknowledged packet numbers, including the new packet. unacknowledged packet numbers, including the new packet.
For example, if an endpoint has received an acknowledgment for packet For example, if an endpoint has received an acknowledgment for packet
0x6afa2f, sending a packet with a number of 0x6b4264 requires a 0x6afa2f, sending a packet with a number of 0x6b4264 requires a
16-bit or larger packet number encoding; whereas a 32-bit packet 16-bit or larger packet number encoding; whereas a 32-bit packet
number is needed to send a packet with a number of 0x6bc107. number is needed to send a packet with a number of 0x6bc107.
Version Negotiation (Section 5.3) and Server Stateless Retry Version Negotiation (Section 5.3) and Retry (Section 5.4.2) packets
(Section 5.4.2) packets have special rules for populating the packet have special rules for populating the packet number field.
number field.
5.7.1. Initial Packet Number 5.7.1. Initial Packet Number
The initial value for packet number MUST be selected from an uniform The initial value for packet number MUST be selected randomly from a
random distribution between 0 and 2^31-1. That is, the lower 31 bits range between 0 and 2^32 - 1025 (inclusive). This value is selected
of the packet number are randomized. [RFC4086] provides guidance on so that Initial and Handshake packets exercise as many possible
the generation of random values. values for the Packet Number field as possible.
The first set of packets sent by an endpoint MUST include the low Limiting the range allows both for loss of packets and for any
32-bits of the packet number. Once any packet has been acknowledged, stateless exchanges. Packet numbers are incremented for subsequent
subsequent packets can use a shorter packet number encoding. packets, but packet loss and stateless handling can both mean that
the first packet sent by an endpoint isn't necessarily the first
packet received by its peer. The first packet received by a peer
cannot be 2^32 or greater or the recipient will incorrectly assume a
packet number that is 2^32 values lower and discard the packet.
Use of a secure random number generator [RFC4086] is not necessary
for generating the initial packet number, nor is it necessary that
the value be uniformly distributed.
5.8. Handling Packets from Different Versions 5.8. Handling Packets from Different Versions
Between different versions the following things are guaranteed to Between different versions the following things are guaranteed to
remain constant: remain constant:
o the location of the header form flag, o the location of the header form flag,
o the location of the Connection ID flag in short headers, o the location of the Omit Connection ID flag in short headers,
o the location and size of the Connection ID field in both header o the location and size of the Connection ID field in both header
forms, forms,
o the location and size of the Version field in long headers, o the location and size of the Version field in long headers,
o the format and semantics of the Version Negotiation packet.
o the location and size of the Packet Number field in long headers,
and
o the type, format and semantics of the Version Negotiation packet.
Implementations MUST assume that an unsupported version uses an Implementations MUST assume that an unsupported version uses an
unknown packet format. All other fields MUST be ignored when unknown packet format. All other fields MUST be ignored when
processing a packet that contains an unsupported version. processing a packet that contains an unsupported version.
6. Frames and Frame Types 6. Frames and Frame Types
The payload of cleartext packets and the plaintext after decryption The payload of all packets, after removing packet protection,
of protected payloads consists of a sequence of frames, as shown in consists of a sequence of frames, as shown in Figure 4. Version
Figure 4. Negotiation and Stateless Reset do not contain frames.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame 1 (*) ... | Frame 1 (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame 2 (*) ... | Frame 2 (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 20, line 8 skipping to change at page 20, line 8
Frame types are listed in Table 3. Note that the Frame Type byte in Frame types are listed in Table 3. Note that the Frame Type byte in
STREAM and ACK frames is used to carry other frame-specific flags. STREAM and ACK frames is used to carry other frame-specific flags.
For all other frames, the Frame Type byte simply identifies the For all other frames, the Frame Type byte simply identifies the
frame. These frames are explained in more detail as they are frame. These frames are explained in more detail as they are
referenced later in the document. referenced later in the document.
+-------------+-------------------+--------------+ +-------------+-------------------+--------------+
| Type Value | Frame Type Name | Definition | | Type Value | Frame Type Name | Definition |
+-------------+-------------------+--------------+ +-------------+-------------------+--------------+
| 0x00 | PADDING | Section 8.1 | | 0x00 | PADDING | Section 8.2 |
| | | | | | | |
| 0x01 | RST_STREAM | Section 8.2 | | 0x01 | RST_STREAM | Section 8.3 |
| | | | | | | |
| 0x02 | CONNECTION_CLOSE | Section 8.3 | | 0x02 | CONNECTION_CLOSE | Section 8.4 |
| | | | | | | |
| 0x03 | APPLICATION_CLOSE | Section 8.4 | | 0x03 | APPLICATION_CLOSE | Section 8.5 |
| | | | | | | |
| 0x04 | MAX_DATA | Section 8.5 | | 0x04 | MAX_DATA | Section 8.6 |
| | | | | | | |
| 0x05 | MAX_STREAM_DATA | Section 8.6 | | 0x05 | MAX_STREAM_DATA | Section 8.7 |
| | | | | | | |
| 0x06 | MAX_STREAM_ID | Section 8.7 | | 0x06 | MAX_STREAM_ID | Section 8.8 |
| | | | | | | |
| 0x07 | PING | Section 8.8 | | 0x07 | PING | Section 8.9 |
| | | | | | | |
| 0x08 | BLOCKED | Section 8.9 | | 0x08 | BLOCKED | Section 8.10 |
| | | | | | | |
| 0x09 | STREAM_BLOCKED | Section 8.10 | | 0x09 | STREAM_BLOCKED | Section 8.11 |
| | | | | | | |
| 0x0a | STREAM_ID_BLOCKED | Section 8.11 | | 0x0a | STREAM_ID_BLOCKED | Section 8.12 |
| | | | | | | |
| 0x0b | NEW_CONNECTION_ID | Section 8.12 | | 0x0b | NEW_CONNECTION_ID | Section 8.13 |
| | | | | | | |
| 0x0c | STOP_SENDING | Section 8.13 | | 0x0c | STOP_SENDING | Section 8.14 |
| | | | | | | |
| 0xa0 - 0xbf | ACK | Section 8.14 | | 0x0d | PONG | Section 8.15 |
| | | | | | | |
| 0xc0 - 0xff | STREAM | Section 8.15 | | 0x0e | ACK | Section 8.16 |
| | | |
| 0x10 - 0x17 | STREAM | Section 8.17 |
+-------------+-------------------+--------------+ +-------------+-------------------+--------------+
Table 3: Frame Types Table 3: Frame Types
7. Life of a Connection 7. Life of a Connection
A QUIC connection is a single conversation between two QUIC A QUIC connection is a single conversation between two QUIC
endpoints. QUIC's connection establishment intertwines version endpoints. QUIC's connection establishment intertwines version
negotiation with the cryptographic and transport handshakes to reduce negotiation with the cryptographic and transport handshakes to reduce
connection establishment latency, as described in Section 7.3. Once connection establishment latency, as described in Section 7.3. Once
established, a connection may migrate to a different IP or port at established, a connection may migrate to a different IP or port at
either endpoint, due to NAT rebinding or mobility, as described in either endpoint, due to NAT rebinding or mobility, as described in
Section 7.7. Finally a connection may be terminated by either Section 7.7. Finally a connection may be terminated by either
endpoint, as described in Section 7.8. endpoint, as described in Section 7.9.
7.1. Matching Packets to Connections 7.1. Matching Packets to Connections
Incoming packets are classified on receipt. Packets can either be Incoming packets are classified on receipt. Packets can either be
associated with an existing connection, be discarded, or - for associated with an existing connection, be discarded, or - for
servers - potentially create a new connection. servers - potentially create a new connection.
Packets that can be associated with an existing connection are Packets that can be associated with an existing connection are
handled according to the current state of that connection. Packets handled according to the current state of that connection. Packets
are associated with existing connections using connection ID if it is are associated with existing connections using connection ID if it is
present; this might include connection IDs that were advertised using present; this might include connection IDs that were advertised using
NEW_CONNECTION_ID (Section 8.12). Packets without connection IDs and NEW_CONNECTION_ID (Section 8.13). Packets without connection IDs and
long-form packets for connections that have incomplete cryptographic long-form packets for connections that have incomplete cryptographic
handshakes are associated with an existing connection using the tuple handshakes are associated with an existing connection using the tuple
of source and destination IP addresses and ports. of source and destination IP addresses and ports.
A packet that uses the short header could be associated with an A packet that uses the short header could be associated with an
existing connection with an incomplete cryptographic handshake. Such existing connection with an incomplete cryptographic handshake. Such
a packet could be a valid packet that has been reordered with respect a packet could be a valid packet that has been reordered with respect
to the long-form packets that will complete the cryptographic to the long-form packets that will complete the cryptographic
handshake. This might happen after the final set of cryptographic handshake. This might happen after the final set of cryptographic
handshake messages from either peer. These packets are expected to handshake messages from either peer. These packets are expected to
skipping to change at page 21, line 52 skipping to change at page 21, line 52
connection SHOULD be discarded if it is not buffered. Discarded connection SHOULD be discarded if it is not buffered. Discarded
packets MAY be logged for diagnostic or security purposes. packets MAY be logged for diagnostic or security purposes.
For servers, packets that aren't associated with a connection For servers, packets that aren't associated with a connection
potentially create a new connection. However, only packets that use potentially create a new connection. However, only packets that use
the long packet header and that are at least the minimum size defined the long packet header and that are at least the minimum size defined
for the protocol version can be initial packets. A server MAY for the protocol version can be initial packets. A server MAY
discard packets with a short header or packets that are smaller than discard packets with a short header or packets that are smaller than
the smallest minimum size for any version that the server supports. the smallest minimum size for any version that the server supports.
A server that discards a packet that cannot be associated with a A server that discards a packet that cannot be associated with a
connection MAY also generate a stateless reset (Section 7.8.4). connection MAY also generate a stateless reset (Section 7.9.4).
This version of QUIC defines a minimum size for initial packets of This version of QUIC defines a minimum size for initial packets of
1200 octets (see Section 9). Versions of QUIC that define smaller 1200 octets (see Section 9). Versions of QUIC that define smaller
minimum initial packet sizes need to be aware that initial packets minimum initial packet sizes need to be aware that initial packets
will be discarded without action by servers that only support will be discarded without action by servers that only support
versions with larger minimums. Clients that support multiple QUIC versions with larger minimums. Clients that support multiple QUIC
versions can avoid this problem by ensuring that they increase the versions can avoid this problem by ensuring that they increase the
size of their initial packets to the largest minimum size across all size of their initial packets to the largest minimum size across all
of the QUIC versions they support. Servers need to recognize initial of the QUIC versions they support. Servers need to recognize initial
packets that are the minimum size of all QUIC versions they support. packets that are the minimum size of all QUIC versions they support.
7.2. Version Negotiation 7.2. Version Negotiation
QUIC's connection establishment begins with version negotiation, QUIC's connection establishment begins with version negotiation,
since all communication between the endpoints, including packet and since all communication between the endpoints, including packet and
frame formats, relies on the two endpoints agreeing on a version. frame formats, relies on the two endpoints agreeing on a version.
A QUIC connection begins with a client sending a Client Initial A QUIC connection begins with a client sending an Initial packet
packet (Section 5.4.1). The details of the handshake mechanisms are (Section 5.4.1). The details of the handshake mechanisms are
described in Section 7.3, but all of the initial packets sent from described in Section 7.3, but any Initial packet sent from the client
the client to the server MUST use the long header format - which to the server MUST use the long header format - which includes the
includes the version of the protocol being used - and they MUST be version of the protocol being used - and they MUST be padded to at
padded to at least 1200 octets. least 1200 octets.
The server receives this packet and determines whether it potentially The server receives this packet and determines whether it potentially
creates a new connection (see Section 7.1). If the packet might creates a new connection (see Section 7.1). If the packet might
generate a new connection, the server then checks whether it generate a new connection, the server then checks whether it
understands the version that the client has selected. understands the version that the client has selected.
If the packet contains a version that is acceptable to the server, If the packet contains a version that is acceptable to the server,
the server proceeds with the handshake (Section 7.3). This commits the server proceeds with the handshake (Section 7.3). This commits
the server to the version that the client selected. the server to the version that the client selected.
skipping to change at page 23, line 8 skipping to change at page 23, line 8
unacceptable version if that packet could create a new connection. unacceptable version if that packet could create a new connection.
This allows a server to process packets with unsupported versions This allows a server to process packets with unsupported versions
without retaining state. Though either the Client Initial packet or without retaining state. Though either the Client Initial packet or
the version negotiation packet that is sent in response could be the version negotiation packet that is sent in response could be
lost, the client will send new packets until it successfully receives lost, the client will send new packets until it successfully receives
a response or it abandons the connection attempt. a response or it abandons the connection attempt.
7.2.2. Handling Version Negotiation Packets 7.2.2. Handling Version Negotiation Packets
When the client receives a Version Negotiation packet, it first When the client receives a Version Negotiation packet, it first
checks that the packet number and connection ID match the values the checks that the connection ID matches the connection ID the client
client sent in a previous packet on the same connection. If this sent. If this check fails, the packet MUST be discarded.
check fails, the packet MUST be discarded.
Once the Version Negotiation packet is determined to be valid, the Once the Version Negotiation packet is determined to be valid, the
client then selects an acceptable protocol version from the list client then selects an acceptable protocol version from the list
provided by the server. The client then attempts to create a provided by the server. The client then attempts to create a
connection using that version. Though the contents of the Client connection using that version. Though the contents of the Client
Initial packet the client sends might not change in response to Initial packet the client sends might not change in response to
version negotiation, a client MUST increase the packet number it uses version negotiation, a client MUST increase the packet number it uses
on every packet it sends. Packets MUST continue to use long headers on every packet it sends. Packets MUST continue to use long headers
and MUST include the new negotiated protocol version. and MUST include the new negotiated protocol version.
skipping to change at page 23, line 48 skipping to change at page 23, line 47
cryptographic handshake (see Section 7.4.4). cryptographic handshake (see Section 7.4.4).
7.2.3. Using Reserved Versions 7.2.3. Using Reserved Versions
For a server to use a new version in the future, clients must For a server to use a new version in the future, clients must
correctly handle unsupported versions. To help ensure this, a server correctly handle unsupported versions. To help ensure this, a server
SHOULD include a reserved version (see Section 4) while generating a SHOULD include a reserved version (see Section 4) 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. maintaining state for packets that it rejects in this fashion. The
However, when the server generates a Version Negotiation packet, it validation of version negotiation (see Section 7.4.4) only validates
cannot randomly generate a reserved version number. This is because the result of version negotiation, which is the same no matter which
the server is required to include the same value in its transport reserved version was sent. A server MAY therefore send different
parameters (see Section 7.4.4). To avoid the selected version number reserved version numbers in the Version Negotiation Packet and in its
changing during connection establishment, the reserved version SHOULD transport parameters.
be generated as a function of values that will be available to the
server when later generating its handshake packets.
A pseudorandom function that takes client address information (IP and
port) and the client selected version as input would ensure that
there is sufficient variability in the values that a server uses.
A client MAY send a packet using a reserved version number. This can A client MAY send a packet using a reserved version number. This can
be used to solicit a list of supported versions from a server. be used to solicit a list of supported versions from a server.
7.3. Cryptographic and Transport Handshake 7.3. Cryptographic and Transport Handshake
QUIC relies on a combined cryptographic and transport handshake to QUIC relies on a combined cryptographic and transport handshake to
minimize connection establishment latency. QUIC allocates stream 0 minimize connection establishment latency. QUIC allocates stream 0
for the cryptographic handshake. Version 0x00000001 of QUIC uses TLS for the cryptographic handshake. Version 0x00000001 of QUIC uses TLS
1.3 as described in [QUIC-TLS]; a different QUIC version number could 1.3 as described in [QUIC-TLS]; a different QUIC version number could
skipping to change at page 26, line 10 skipping to change at page 26, line 10
The format of the transport parameters is the TransportParameters The format of the transport parameters is the TransportParameters
struct from Figure 6. This is described using the presentation struct from Figure 6. This is described using the presentation
language from Section 3 of [I-D.ietf-tls-tls13]. language from Section 3 of [I-D.ietf-tls-tls13].
uint32 QuicVersion; uint32 QuicVersion;
enum { enum {
initial_max_stream_data(0), initial_max_stream_data(0),
initial_max_data(1), initial_max_data(1),
initial_max_stream_id(2), initial_max_stream_id_bidi(2),
idle_timeout(3), idle_timeout(3),
omit_connection_id(4), omit_connection_id(4),
max_packet_size(5), max_packet_size(5),
stateless_reset_token(6), stateless_reset_token(6),
ack_delay_exponent(7),
initial_max_stream_id_uni(8),
(65535) (65535)
} TransportParameterId; } TransportParameterId;
struct { struct {
TransportParameterId parameter; TransportParameterId parameter;
opaque value<0..2^16-1>; opaque value<0..2^16-1>;
} TransportParameter; } TransportParameter;
struct { struct {
select (Handshake.msg_type) { select (Handshake.msg_type) {
case client_hello: case client_hello:
QuicVersion negotiated_version;
QuicVersion initial_version; QuicVersion initial_version;
case encrypted_extensions: case encrypted_extensions:
QuicVersion negotiated_version;
QuicVersion supported_versions<4..2^8-4>; QuicVersion supported_versions<4..2^8-4>;
case new_session_ticket: case new_session_ticket:
struct {}; struct {};
}; };
TransportParameter parameters<30..2^16-1>; TransportParameter parameters<30..2^16-1>;
} TransportParameters; } TransportParameters;
Figure 6: Definition of TransportParameters Figure 6: Definition of TransportParameters
skipping to change at page 27, line 20 skipping to change at page 27, line 20
7.4.1. Transport Parameter Definitions 7.4.1. Transport Parameter Definitions
An endpoint MUST include the following parameters in its encoded An endpoint MUST include the following parameters in its encoded
TransportParameters: TransportParameters:
initial_max_stream_data (0x0000): The initial stream maximum data initial_max_stream_data (0x0000): The initial stream maximum data
parameter contains the initial value for the maximum data that can parameter contains the initial value for the maximum data that can
be sent on any newly created stream. This parameter is encoded as be sent on any newly created stream. This parameter is encoded as
an unsigned 32-bit integer in units of octets. This is equivalent an unsigned 32-bit integer in units of octets. This is equivalent
to an implicit MAX_STREAM_DATA frame (Section 8.6) being sent on to an implicit MAX_STREAM_DATA frame (Section 8.7) being sent on
all streams immediately after opening. all streams immediately after opening.
initial_max_data (0x0001): The initial maximum data parameter initial_max_data (0x0001): The initial maximum data parameter
contains the initial value for the maximum amount of data that can contains the initial value for the maximum amount of data that can
be sent on the connection. This parameter is encoded as an be sent on the connection. This parameter is encoded as an
unsigned 32-bit integer in units of 1024 octets. That is, the unsigned 32-bit integer in units of octets. This is equivalent to
value here is multiplied by 1024 to determine the actual maximum sending a MAX_DATA (Section 8.6) for the connection immediately
value. This is equivalent to sending a MAX_DATA (Section 8.5) for
the connection immediately after completing the handshake.
initial_max_stream_id (0x0002): The initial maximum stream ID
parameter contains the initial maximum stream number the peer may
initiate, encoded as an unsigned 32-bit integer. This is
equivalent to sending a MAX_STREAM_ID (Section 8.7) immediately
after completing the handshake. after completing the handshake.
idle_timeout (0x0003): The idle timeout is a value in seconds that idle_timeout (0x0003): The idle timeout is a value in seconds that
is encoded as an unsigned 16-bit integer. The maximum value is is encoded as an unsigned 16-bit integer. The maximum value is
600 seconds (10 minutes). 600 seconds (10 minutes).
A server MUST include the following transport parameters: A server MUST 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 7.8.4. This parameter is verifying a stateless reset, see Section 7.9.4. This parameter is
a sequence of 16 octets. a sequence of 16 octets.
A client MUST NOT include a stateless reset token. A server MUST A client MUST NOT include a stateless reset token. A server MUST
treat receipt of a stateless_reset_token transport parameter as a treat receipt of a stateless_reset_token transport parameter as a
connection error of type TRANSPORT_PARAMETER_ERROR. connection error of type TRANSPORT_PARAMETER_ERROR.
An endpoint MAY use the following transport parameters: An endpoint MAY use the following transport parameters:
initial_max_stream_id_bidi (0x0002): The initial maximum stream ID
parameter contains the initial maximum stream number the peer may
initiate for bidirectional streams, encoded as an unsigned 32-bit
integer. This value MUST be a valid bidirectional stream ID for a
peer-initiated stream (that is, the two least significant bits are
set to 0 by a server and to 1 by a client). If an invalid value
is provided, the recipient MUST generate a connection error of
type TRANSPORT_PARAMETER_ERROR. Setting this parameter is
equivalent to sending a MAX_STREAM_ID (Section 8.8) immediately
after completing the handshake. The maximum bidirectional stream
ID is set to 0 if this parameter is absent, preventing the
creation of new bidirectional streams until a MAX_STREAM_ID frame
is sent. Note that a default value of 0 does not prevent the
cryptographic handshake stream (that is, stream 0) from being
used.
initial_max_stream_id_uni (0x0008): The initial maximum stream ID
parameter contains the initial maximum stream number the peer may
initiate for unidirectional streams, encoded as an unsigned 32-bit
integer. The value MUST be a valid unidirectional ID for the
recipient (that is, the two least significant bits are set to 2 by
a server and to 3 by a client). If an invalid value is provided,
the recipient MUST generate a connection error of type
TRANSPORT_PARAMETER_ERROR. Setting this parameter is equivalent
to sending a MAX_STREAM_ID (Section 8.8) immediately after
completing the handshake. The maximum unidirectional stream ID is
set to 0 if this parameter is absent, preventing the creation of
new unidirectional streams until a MAX_STREAM_ID frame is sent.
omit_connection_id (0x0004): The omit connection identifier omit_connection_id (0x0004): The omit connection identifier
parameter indicates that packets sent to the endpoint that parameter indicates that packets sent to the endpoint that
advertises this parameter can omit the connection ID. This can be advertises this parameter MAY omit the connection ID in packets
used by an endpoint where it knows that source and destination IP using short header format. This can be used by an endpoint where
address and port are sufficient for it to identify a connection. it knows that source and destination IP address and port are
This parameter is zero length. Absence this parameter indicates sufficient for it to identify a connection. This parameter is
that the endpoint relies on the connection ID being present in zero length. Absence of this parameter means that the connection
every packet. ID MUST be present in every packet sent to this endpoint.
max_packet_size (0x0005): The maximum packet size parameter places a max_packet_size (0x0005): The maximum packet size parameter places a
limit on the size of packets that the endpoint is willing to limit on the size of packets that the endpoint is willing to
receive, encoded as an unsigned 16-bit integer. This indicates receive, encoded as an unsigned 16-bit integer. This indicates
that packets larger than this limit will be dropped. The default that packets larger than this limit will be dropped. The default
for this parameter is the maximum permitted UDP payload of 65527. for this parameter is the maximum permitted UDP payload of 65527.
Values below 1200 are invalid. This limit only applies to Values below 1200 are invalid. This limit only applies to
protected packets (Section 5.5). protected packets (Section 5.5).
ack_delay_exponent (0x0007): An 8-bit unsigned integer value
indicating an exponent used to decode the ACK Delay field in the
ACK frame, see Section 8.16. If this value is absent, a default
value of 3 is assumed (indicating a multiplier of 8). Values
above 20 are invalid.
7.4.2. Values of Transport Parameters for 0-RTT 7.4.2. Values of Transport Parameters for 0-RTT
Transport parameters from the server MUST be remembered by the client Transport parameters from the server MUST be remembered by the client
for use with 0-RTT data. If the TLS NewSessionTicket message for use with 0-RTT data. If the TLS NewSessionTicket message
includes the quic_transport_parameters extension, then those values includes the quic_transport_parameters extension, then those values
are used for the server values when establishing a new connection are used for the server values when establishing a new connection
using that ticket. Otherwise, the transport parameters that the using that ticket. Otherwise, the transport parameters that the
server advertises during connection establishment are used. server advertises during connection establishment are used.
A server can remember the transport parameters that it advertised, or A server can remember the transport parameters that it advertised, or
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recover the information when accepting 0-RTT data. A server uses the recover the information when accepting 0-RTT data. A server uses the
transport parameters in determining whether to accept 0-RTT data. transport parameters in determining whether to accept 0-RTT data.
A server MAY accept 0-RTT and subsequently provide different values A server MAY accept 0-RTT and subsequently provide different values
for transport parameters for use in the new connection. If 0-RTT for transport parameters for use in the new connection. If 0-RTT
data is accepted by the server, the server MUST NOT reduce any limits data is accepted by the server, the server MUST NOT reduce any limits
or alter any values that might be violated by the client with its or alter any values that might be violated by the client with its
0-RTT data. In particular, a server that accepts 0-RTT data MUST NOT 0-RTT data. In particular, a server that accepts 0-RTT data MUST NOT
set values for initial_max_data or initial_max_stream_data that are set values for initial_max_data or initial_max_stream_data that are
smaller than the remembered value of those parameters. Similarly, a smaller than the remembered value of those parameters. Similarly, a
server MUST NOT reduce the value of initial_max_stream_id. server MUST NOT reduce the value of initial_max_stream_id_bidi or
initial_max_stream_id_uni.
Omitting or setting a zero value for certain transport parameters can
result in 0-RTT data being enabled, but not usable. The following
transport parameters SHOULD be set to non-zero values for 0-RTT:
initial_max_stream_id_bidi, initial_max_stream_id_uni,
initial_max_data, initial_max_stream_data.
A server MUST reject 0-RTT data or even abort a handshake if the A server MUST reject 0-RTT data or even abort a handshake if the
implied values for transport parameters cannot be supported. implied values for transport parameters cannot be supported.
7.4.3. New Transport Parameters 7.4.3. New Transport Parameters
New transport parameters can be used to negotiate new protocol New transport parameters can be used to negotiate new protocol
behavior. An endpoint MUST ignore transport parameters that it does behavior. An endpoint MUST ignore transport parameters that it does
not support. Absence of a transport parameter therefore disables any not support. Absence of a transport parameter therefore disables any
optional protocol feature that is negotiated using the parameter. optional protocol feature that is negotiated using the parameter.
New transport parameters can be registered according to the rules in New transport parameters can be registered according to the rules in
Section 14.1. Section 14.1.
7.4.4. Version Negotiation Validation 7.4.4. Version Negotiation Validation
The transport parameters include three fields that encode version Though the cryptographic handshake has integrity protection, two
information. These retroactively authenticate the version forms of QUIC version downgrade are possible. In the first, an
negotiation (see Section 7.2) that is performed prior to the attacker replaces the QUIC version in the Initial packet. In the
cryptographic handshake. second, a fake Version Negotiation packet is sent by an attacker. To
protect against these attacks, the transport parameters include three
fields that encode version information. These parameters are used to
retroactively authenticate the choice of version (see Section 7.2).
The cryptographic handshake provides integrity protection for the The cryptographic handshake provides integrity protection for the
negotiated version as part of the transport parameters (see negotiated version as part of the transport parameters (see
Section 7.4). As a result, modification of version negotiation Section 7.4). As a result, attacks on version negotiation by an
packets by an attacker can be detected. attacker can be detected.
The client includes two fields in the transport parameters:
o The negotiated_version is the version that was finally selected
for use. This MUST be identical to the value that is on the
packet that carries the ClientHello. A server that receives a
negotiated_version that does not match the version of QUIC that is
in use MUST terminate the connection with a
VERSION_NEGOTIATION_ERROR error code.
o The initial_version is the version that the client initially The client includes the initial_version field in its transport
attempted to use. If the server did not send a version parameters. The initial_version is the version that the client
negotiation packet Section 5.3, this will be identical to the initially attempted to use. If the server did not send a version
negotiated_version. negotiation packet Section 5.3, this will be identical to the
negotiated_version field in the server transport parameters.
A server that processes all packets in a stateful fashion can A server that processes all packets in a stateful fashion can
remember how version negotiation was performed and validate the remember how version negotiation was performed and validate the
initial_version value. initial_version value.
A server that does not maintain state for every packet it receives A server that does not maintain state for every packet it receives
(i.e., a stateless server) uses a different process. If the initial (i.e., a stateless server) uses a different process. If the
and negotiated versions are the same, a stateless server can accept initial_version matches the version of QUIC that is in use, a
the value. stateless server can accept the value.
If the initial version is different from the negotiated_version, a If the initial_version is different from the version of QUIC that is
stateless server MUST check that it would have sent a version in use, a stateless server MUST check that it would have sent a
negotiation packet if it had received a packet with the indicated version negotiation packet if it had received a packet with the
initial_version. If a server would have accepted the version indicated initial_version. If a server would have accepted the
included in the initial_version and the value differs from the value version included in the initial_version and the value differs from
of negotiated_version, the server MUST terminate the connection with the QUIC version that is in use, the server MUST terminate the
a VERSION_NEGOTIATION_ERROR error. connection with a VERSION_NEGOTIATION_ERROR error.
The server includes both the version of QUIC that is in use and a
list of the QUIC versions that the server supports.
The negotiated_version field is the version that is in use. This
MUST be set by the server to the value that is on the Initial packet
that it accepts (not an Initial packet that triggers a Retry or
Version Negotiation packet). A client that receives a
negotiated_version that does not match the version of QUIC that is in
use MUST terminate the connection with a VERSION_NEGOTIATION_ERROR
error code.
The server includes a list of versions that it would send in any The server includes a list of versions that it would send in any
version negotiation packet (Section 5.3) in supported_versions. The version negotiation packet (Section 5.3) in the supported_versions
server populates this field even if it did not send a version field. The server populates this field even if it did not send a
negotiation packet. This field is absent if the parameters are version negotiation packet. This field is absent if the parameters
included in a NewSessionTicket message. are included in a NewSessionTicket message.
The client can validate that the negotiated_version is included in The client validates that the negotiated_version is included in the
the supported_versions list and - if version negotiation was supported_versions list and - if version negotiation was performed -
performed - that it would have selected the negotiated version. A that it would have selected the negotiated version. A client MUST
client MUST terminate the connection with a VERSION_NEGOTIATION_ERROR terminate the connection with a VERSION_NEGOTIATION_ERROR error code
error code if the negotiated_version value is not included in the if the current QUIC version is not listed in the supported_versions
supported_versions list. A client MUST terminate with a list. A client MUST terminate with a VERSION_NEGOTIATION_ERROR error
VERSION_NEGOTIATION_ERROR error code if version negotiation occurred code if version negotiation occurred but it would have selected a
but it would have selected a different version based on the value of different version based on the value of the supported_versions list.
the supported_versions list.
When an endpoint accepts multiple QUIC versions, it can potentially When an endpoint accepts multiple QUIC versions, it can potentially
interpret transport parameters as they are defined by any of the QUIC interpret transport parameters as they are defined by any of the QUIC
versions it supports. The version field in the QUIC packet header is versions it supports. The version field in the QUIC packet header is
authenticated using transport parameters. The position and the authenticated using transport parameters. The position and the
format of the version fields in transport parameters MUST either be format of the version fields in transport parameters MUST either be
identical across different QUIC versions, or be unambiguously identical across different QUIC versions, or be unambiguously
different to ensure no confusion about their interpretation. One way different to ensure no confusion about their interpretation. One way
that a new format could be introduced is to define a TLS extension that a new format could be introduced is to define a TLS extension
with a different codepoint. with a different codepoint.
7.5. Stateless Retries 7.5. Stateless Retries
A server can process an initial cryptographic handshake messages from A server can process an initial cryptographic handshake messages from
a client without committing any state. This allows a server to a client without committing any state. This allows a server to
perform address validation (Section 7.6, or to defer connection perform address validation (Section 7.6, or to defer connection
establishment costs. establishment costs.
A server that generates a response to an initial packet without A server that generates a response to an initial packet without
retaining connection state MUST use the Server Stateless Retry packet retaining connection state MUST use the Retry packet (Section 5.4.2).
(Section 5.4.2). This packet causes a client to reset its transport This packet causes a client to reset its transport state and to
state and to continue the connection attempt with new connection continue the connection attempt with new connection state while
state while maintaining the state of the cryptographic handshake. maintaining the state of the cryptographic handshake.
A server MUST NOT send multiple Server Stateless Retry packets in A server MUST NOT send multiple Retry packets in response to a client
response to a client handshake packet. Thus, any cryptographic handshake packet. Thus, any cryptographic handshake message that is
handshake message that is sent MUST fit within a single packet. sent MUST fit within a single packet.
In TLS, the Server Stateless Retry packet type is used to carry the In TLS, the Retry packet type is used to carry the HelloRetryRequest
HelloRetryRequest message. message.
7.6. Proof of Source Address Ownership 7.6. Proof of Source Address Ownership
Transport protocols commonly spend a round trip checking that a Transport protocols commonly spend a round trip checking that a
client owns the transport address (IP and port) that it claims. client owns the transport address (IP and port) that it claims.
Verifying that a client can receive packets sent to its claimed Verifying that a client can receive packets sent to its claimed
transport address protects against spoofing of this information by transport address protects against spoofing of this information by
malicious clients. malicious clients.
This technique is used primarily to avoid QUIC from being used for This technique is used primarily to avoid QUIC from being used for
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To send additional data prior to completing the cryptographic To send additional data prior to completing the cryptographic
handshake, the server then needs to validate that the client owns the handshake, the server then needs to validate that the client owns the
address that it claims. address that it claims.
Source address validation is therefore performed during the Source address validation is therefore performed during the
establishment of a connection. TLS provides the tools that support establishment of a connection. TLS provides the tools that support
the feature, but basic validation is performed by the core transport the feature, but basic validation is performed by the core transport
protocol. protocol.
A different type of source address validation is performed after a
connection migration, see Section 7.7.2.
7.6.1. Client Address Validation Procedure 7.6.1. Client Address Validation Procedure
QUIC uses token-based address validation. Any time the server wishes QUIC uses token-based address validation. Any time the server wishes
to validate a client address, it provides the client with a token. to validate a client address, it provides the client with a token.
As long as the token cannot be easily guessed (see Section 7.6.3), if As long as the token cannot be easily guessed (see Section 7.6.3), if
the client is able to return that token, it proves to the server that the client is able to return that token, it proves to the server that
it received the token. it received the token.
During the processing of the cryptographic handshake messages from a During the processing of the cryptographic handshake messages from a
client, TLS will request that QUIC make a decision about whether to client, TLS will request that QUIC make a decision about whether to
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QUIC connections are identified by their 64-bit Connection ID. QUIC connections are identified by their 64-bit Connection ID.
QUIC's consistent connection ID allows connections to survive changes QUIC's consistent connection ID allows connections to survive changes
to the client's IP and/or port, such as those caused by client or to the client's IP and/or port, such as those caused by client or
server migrating to a new network. Connection migration allows a server migrating to a new network. Connection migration allows a
client to retain any shared state with a connection when they move client to retain any shared state with a connection when they move
networks. This includes state that can be hard to recover such as networks. This includes state that can be hard to recover such as
outstanding requests, which might otherwise be lost with no easy way outstanding requests, which might otherwise be lost with no easy way
to retry them. to retry them.
An endpoint that receives packets that contain a source IP address
and port that has not yet been used can start sending new packets
with those as a destination IP address and port. Packets exchanged
between endpoints can then follow the new path.
Due to variations in path latency or packet reordering, packets from
different source addresses might be reordered. The packet with the
highest packet number MUST be used to determine which path to use.
Endpoints also need to be prepared to receive packets from an older
source address.
An endpoint MUST validate that its peer can receive packets at the
new address before sending any significant quantity of data to that
address, or it risks being used for denial of service. See
Section 7.7.2 for details.
7.7.1. Privacy Implications of Connection Migration 7.7.1. 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. A client passive observer to correlate activity between those paths. A client
that moves between networks might not wish to have their activity that moves between networks might not wish to have their activity
correlated by any entity other than a server. The NEW_CONNECTION_ID correlated by any entity other than a server. The NEW_CONNECTION_ID
message can be sent by a server to provide an unlinkable connection message can be sent by a server to provide an unlinkable connection
ID for use in case the client wishes to explicitly break linkability ID for use in case the client wishes to explicitly break linkability
between two points of network attachment. between two points of network attachment.
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Gap = HKDF-Expand-Label(packet_number_secret, Gap = HKDF-Expand-Label(packet_number_secret,
"QUIC packet sequence gap", sequence, 4) "QUIC packet sequence gap", sequence, 4)
The output of HKDF-Expand-Label is interpreted as a big-endian The output of HKDF-Expand-Label is interpreted as a big-endian
number. "packet_number_secret" is derived from the TLS key exchange, number. "packet_number_secret" is derived from the TLS key exchange,
as described in Section 5.6 of [QUIC-TLS]. as described in Section 5.6 of [QUIC-TLS].
7.7.2. Address Validation for Migrated Connections 7.7.2. Address Validation for Migrated Connections
TODO: see issue #161 An endpoint that receives a packet from a new remote IP address and
port (or just a new remote port) on packets from its peer is likely
seeing a connection migration at the peer.
7.8. Connection Termination However, it is also possible that the peer is spoofing its source
address in order to cause the endpoint to send excessive amounts of
data to an unwilling host. If the endpoint sends significantly more
data than the peer, connection migration might be used to amplify the
volume of data that an attacker can generate toward a victim.
Thus, when seeing a new remote transport address, an endpoint MUST
verify that its peer can receive and respond to packets at that new
address. By providing copies of the data that it receives, the peer
proves that it is receiving packets at the new address and consents
to receive data.
Prior to validating the new remote address, and endpoint MUST limit
the amount of data and packets that it sends to its peer. At a
minimum, this needs to consider the possibility that packets are sent
without congestion feedback.
Once a connection is established, address validation is relatively
simple (see Section 7.6 for the process that is used during the
handshake). An endpoint validates a remote address by sending a PING
frame containing a payload that is hard to guess. This frame MUST be
sent in a packet that is sent to the new address. Once a PONG frame
containing the same payload is received, the address is considered to
be valid. The PONG frame can use any path on its return. A PING
frame containing 12 randomly generated [RFC4086] octets is sufficient
to ensure that it is easier to receive the packet than it is to guess
the value correctly.
If the PING frame is determined to be lost, a new PING frame SHOULD
be generated. This PING frame MUST include a new Data field that is
similarly difficult to guess.
If validation of the new remote address fails, after allowing enough
time for possible loss and recovery of packets carrying PING and PONG
frames, the endpoint MUST terminate the connection. When setting
this timer, implementations are cautioned that the new path could
have a longer round trip time than the original. The endpoint MUST
NOT send a CONNECTION_CLOSE frame in this case; it has to assume that
the remote peer does not want to receive any more packets.
If the remote address is validated successfully, the endpoint MAY
increase the rate that it sends on the new path using the state from
the previous path. The capacity available on the new path might not
be the same as the old path. An endpoint MUST NOT restore its send
rate unless it is reasonably sure that the path is the same as the
previous path. For instance, a change in only port number is likely
indicative of a rebinding in a middlebox and not a complete change in
path. This determination likely depends on heuristics, which could
be imperfect; if the new path capacity is significantly reduced,
ultimately this relies on the congestion controller responding to
congestion signals and reduce send rates appropriately.
After verifying an address, the endpoint SHOULD update any address
validation tokens (Section 7.6) that it has issued to its peer if
those are no longer valid based on the changed address.
Address validation using the PING frame MAY be used at any time by
either peer. For instance, an endpoint might check that a peer is
still in possession of its address after a period of quiescence.
Upon seeing a connection migration, an endpoint that sees a new
address MUST abandon any address validation it is performing with
other addresses on the expectation that the validation is likely to
fail. Abandoning address validation primarily means not closing the
connection when a PONG frame is not received, but it could also mean
ceasing retransmissions of the PING frame. An endpoint that doesn't
retransmit a PING frame might receive a PONG frame, which it MUST
ignore.
7.8. Spurious Connection Migrations
A connection migration could be triggered by an attacker that is able
to capture and forward a packet such that it arrives before the
legitimate copy of that packet. Such a packet will appear to be a
legitimate connection migration and the legitimate copy will be
dropped as a duplicate.
After a spurious migration, validation of the source address will
fail because the entity at the source address does not have the
necessary cryptographic keys to read or respond to the PING frame
that is sent to it, even if it wanted to. Such a spurious connection
migration could result in the connection being dropped when the
source address validation fails. This grants an attacker the ability
to terminate the connection.
Receipt of packets with higher packet numbers from the legitimate
address will trigger another connection migration. This will cause
the validation of the address of the spurious migration to be
abandoned.
To ensure that a peer sends packets from the legitimate address
before the validation of the new address can fail, an endpoint SHOULD
attempt to validate the old remote address before attempting to
validate the new address. If the connection migration is spurious,
then the legitimate address will be used to respond and the
connection will migrate back to the old address.
As with any address validation, packets containing retransmissions of
the PING frame validating an address MUST be sent to the address
being validated. Consequently, during a migration of a peer, an
endpoint could be sending to multiple remote addresses.
An endpoint MAY abandon address validation for an address that it
considers to be already valid. That is, if successive connection
migrations occur in quick succession with the final remote address
being identical to the initial remote address, the endpoint MAY
abandon address validation for that address.
7.9. Connection Termination
Connections should remain open until they become idle for a pre- Connections should remain open until they become idle for a pre-
negotiated period of time. A QUIC connection, once established, can negotiated period of time. A QUIC connection, once established, can
be terminated in one of three ways: be terminated in one of three ways:
o idle timeout (Section 7.8.2) o idle timeout (Section 7.9.2)
o immediate close (Section 7.8.3) o immediate close (Section 7.9.3)
o stateless reset (Section 7.8.4) o stateless reset (Section 7.9.4)
7.8.1. Draining Period 7.9.1. Closing and Draining Connection States
After a connection is closed for any reason, an endpoint might The closing and draining connection states exist to ensure that
receive packets from its peer. These packets might have been sent connections close cleanly and that delayed or reordered packets are
prior to receiving any close signal, or they might be retransmissions properly discarded. These states SHOULD persist for three times the
of packets for which acknowledgments were lost. current Retransmission Timeout (RTO) interval as defined in
[QUIC-RECOVERY].
The draining period persists for three times the current An endpoint enters a closing period after initiating an immediate
Retransmission Timeout (RTO) interval as defined in [QUIC-RECOVERY]. close (Section 7.9.3) and optionally after an idle timeout
During this period, new packets can be acknowledged, but no new (Section 7.9.2). While closing, an endpoint MUST NOT send packets
application data can be sent on the connection. unless they contain a CONNECTION_CLOSE or APPLICATION_CLOSE frame
(see Section 7.9.3 for details).
Different treatment is given to packets that are received while a In the closing state, only a packet containing a closing frame can be
connection is in the draining period depending on how the connection sent. An endpoint retains only enough information to generate a
was closed. packet containing a closing frame and to identify packets as
belonging to the connection. The connection ID and QUIC version is
sufficient information to identify packets for a closing connection;
an endpoint can discard all other connection state. An endpoint MAY
retain packet protection keys for incoming packets to allow it to
read and process a closing frame.
An endpoint that is in a draining period MUST NOT send packets unless The draining state is entered once an endpoint receives a signal that
they contain a CONNECTION_CLOSE or APPLICATION_CLOSE frame. its peer is closing or draining. While otherwise identical to the
closing state, an endpoint in the draining state MUST NOT send any
packets. Retaining packet protection keys is unnecessary once a
connection is in the draining state.
Once the draining period has ended, an endpoint SHOULD discard per- An endpoint MAY transition from the closing period to the draining
connection state. This results in new packets on the connection period if it can confirm that its peer is also closing or draining.
being discarded. An endpoint MAY send a stateless reset in response Receiving a closing frame is sufficient confirmation, as is receiving
to any further incoming packets. a stateless reset. The draining period SHOULD end when the closing
period would have ended. In other words, the endpoint can use the
same end time, but cease retransmission of the closing packet.
The draining period does not apply when a stateless reset Disposing of connection state prior to the end of the closing or
(Section 7.8.4) is sent. draining period could cause delayed or reordered packets to be
handled poorly. Endpoints that have some alternative means to ensure
that late-arriving packets on the connection do not create QUIC
state, such as those that are able to close the UDP socket, MAY use
an abbreviated draining period which can allow for faster resource
recovery. Servers that retain an open socket for accepting new
connections SHOULD NOT exit the closing or draining period early.
7.8.2. Idle Timeout Once the closing or draining period has ended, an endpoint SHOULD
discard all connection state. This results in new packets on the
connection being handled generically. For instance, an endpoint MAY
send a stateless reset in response to any further incoming packets.
The draining and closing periods do not apply when a stateless reset
(Section 7.9.4) is sent.
7.9.2. Idle Timeout
A connection that remains idle for longer than the idle timeout (see A connection that remains idle for longer than the idle timeout (see
Section 7.4.1) becomes closed. Either peer removes connection state Section 7.4.1) is closed. A connection enters the draining state
if they have neither sent nor received a packet for this time. 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 peers. A connection enters the draining period when synchronized on both endpoints. An endpoint that sends packets near
the idle timeout expires. During this time, an endpoint that the end of an idle period could have those packets discarded if its
receives new packets MAY choose to restore the connection. peer enters the draining state before the packet is received.
Alternatively, an endpoint that receives packets MAY signal the
timeout using an immediate close.
7.8.3. Immediate Close 7.9.3. Immediate Close
An endpoint sends a CONNECTION_CLOSE or APPLICATION_CLOSE frame to An endpoint sends a closing frame, either CONNECTION_CLOSE or
terminate the connection immediately. Either frame causes all open APPLICATION_CLOSE, to terminate the connection immediately. Either
streams to immediately become closed; open streams can be assumed to closing frame causes all streams to immediately become closed; open
be implicitly reset. After sending or receiving a CONNECTION_CLOSE streams can be assumed to be implicitly reset.
frame, endpoints immediately enter a draining period.
During the draining period, an endpoint that sends a CONNECTION_CLOSE After sending a closing frame, endpoints immediately enter the
or APPLICATION_CLOSE frame SHOULD respond to any subsequent packet closing state. During the closing period, an endpoint that sends a
that it receives with another packet containing either close frame. closing frame SHOULD respond to any packet that it receives with
To reduce the state that an endpoint maintains in this case, it MAY another packet containing a closing frame. To minimize the state
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 either close frame. For number of packets they generate containing a closing frame. For
instance, an endpoint could progressively increase the number of instance, an endpoint could progressively increase the number of
packets that it receives before sending additional packets. packets that it receives before sending additional packets or
increase the time between packets.
Note: Allowing retransmission of a packet contradicts other advice Note: Allowing retransmission of a packet contradicts other advice
in this document that recommends the creation of new packet in this document that recommends the creation of new packet
numbers for every packet. Sending new packet numbers is primarily numbers for every packet. Sending new packet numbers is primarily
of advantage to loss recovery and congestion control, which are of advantage to loss recovery and congestion control, which are
not expected to be relevant for a closed connection. not expected to be relevant for a closed connection.
Retransmitting the final packet requires less state. Retransmitting the final packet requires less state.
After receiving a closing frame, endpoints enter the draining state.
An endpoint that receives a closing frame MAY send a single packet
containing a closing frame before entering the draining state, using
a CONNECTION_CLOSE frame and a NO_ERROR code if appropriate. An
endpoint MUST NOT send further packets, which could result in a
constant exchange of closing frames until the closing period on
either peer ended.
An immediate close can be used after an application protocol has An immediate close can be used after an application protocol has
arranged to close a connection. This might be after the application arranged to close a connection. This might be after the application
protocols negotiates a graceful shutdown. The application protocol protocols negotiates a graceful shutdown. The application protocol
exchanges whatever messages that are needed to cause both endpoints exchanges whatever messages that are needed to cause both endpoints
to agree to close the connection, after which the application to agree to close the connection, after which the application
requests that the connection be closed. The application protocol can requests that the connection be closed. The application protocol can
use an APPLICATION_CLOSE message with an appropriate error code to use an APPLICATION_CLOSE message with an appropriate error code to
signal closure. signal closure.
7.8.4. Stateless Reset 7.9.4. Stateless Reset
A stateless reset is provided as an option of last resort for a A stateless reset is provided as an option of last resort for a
server that does not have access to the state of a connection. A server that does not have access to the state of a connection. A
server crash or outage might result in clients continuing to send server crash or outage might result in clients continuing to send
data to a server that is unable to properly continue the connection. data to a server that is unable to properly continue the connection.
A server that wishes to communicate a fatal connection error MUST use A server that wishes to communicate a fatal connection error MUST use
a CONNECTION_CLOSE or APPLICATION_CLOSE frame if it has sufficient a closing frame if it has sufficient state to do so.
state to do so.
To support this process, the server sends a stateless_reset_token To support this process, the server sends a stateless_reset_token
value during the handshake in the transport parameters. This value value during the handshake in the transport parameters. This value
is protected by encryption, so only client and server know this is protected by encryption, so only client and server know this
value. value.
A server that receives packets that it cannot process sends a packet A server that receives packets that it cannot process sends a packet
in the following layout: in the following layout:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|0|C|K| 00001 | |0|C|K|Type (5) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ [Connection ID (64)] + + [Connection ID (64)] +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packet Number (8/16/32) | | Packet Number (8/16/32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Random Octets (*) ... | Random Octets (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
skipping to change at page 37, line 43 skipping to change at page 42, line 6
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A server copies the connection ID field from the packet that triggers A server copies the connection ID field from the packet that triggers
the stateless reset. A server omits the connection ID if explicitly the stateless reset. A server omits the connection ID if explicitly
configured to do so, or if the client packet did not include a configured to do so, or if the client packet did not include a
connection ID. connection ID.
The Packet Number field is set to a randomized value. The server The Packet Number field is set to a randomized value. The server
SHOULD send a packet with a short header and a type of 0x01. This SHOULD send a packet with a short header and a type of 0x1F. This
produces the shortest possible packet number encoding, which produces the shortest possible packet number encoding, which
minimizes the perceived gap between the last packet that the server minimizes the perceived gap between the last packet that the server
sent and this packet. A server MAY use a different short header sent and this packet. A server MAY use a different short header
type, indicating a different packet number length, but a longer type, indicating a different packet number length, but a longer
packet number encoding might allow this message to be identified as a packet number encoding might allow this message to be identified as a
stateless reset more easily using heuristics. stateless reset more easily using heuristics.
After the first short header octet and optional connection ID, the After the first short header octet and optional connection ID, the
server includes the value of the Stateless Reset Token that it server includes the value of the Stateless Reset Token that it
included in its transport parameters. included in its transport parameters.
skipping to change at page 38, line 23 skipping to change at page 42, line 32
Stateless Reset Token. Stateless Reset Token.
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. possible - indistinguishable from a regular packet.
A stateless reset is not appropriate for signaling error conditions. A stateless reset is not appropriate for signaling error conditions.
An endpoint that wishes to communicate a fatal connection error MUST An endpoint that wishes to communicate a fatal connection error MUST
use a CONNECTION_CLOSE or APPLICATION_CLOSE frame if it has use a CONNECTION_CLOSE or APPLICATION_CLOSE frame if it has
sufficient state to do so. sufficient state to do so.
7.8.4.1. Detecting a Stateless Reset This stateless reset design is specific to QUIC version 1. A server
that supports multiple versions of QUIC needs to generate a stateless
reset that will be accepted by clients that support any version that
the server might support (or might have supported prior to losing
state). Designers of new versions of QUIC need to be aware of this
and either reuse this design, or use a portion of the packet other
than the last 16 octets for carrying data.
7.9.4.1. Detecting a Stateless Reset
A client detects a potential stateless reset when a packet with a A client detects a potential stateless reset when a packet with a
short header either cannot be decrypted or is marked as a duplicate short header either cannot be decrypted or is marked as a duplicate
packet. The client then compares the last 16 octets of the packet packet. The client then compares the last 16 octets of the packet
with the Stateless Reset Token provided by the server in its with the Stateless Reset Token provided by the server in its
transport parameters. If these values are identical, the client MUST transport parameters. If these values are identical, the client MUST
enter the draining period and not send any further packets on this enter the draining period and not send any further packets on this
connection. If the comparison fails, the packet can be discarded. connection. If the comparison fails, the packet can be discarded.
7.8.4.2. Calculating a Stateless Reset Token 7.9.4.2. Calculating a Stateless Reset Token
The stateless reset token MUST be difficult to guess. In order to The stateless reset token MUST be difficult to guess. In order to
create a Stateless Reset Token, a server could randomly generate create a Stateless Reset Token, a server could randomly generate
[RFC4086] a secret for every connection that it creates. However, [RFC4086] a secret for every connection that it creates. However,
this presents a coordination problem when there are multiple servers this presents a coordination problem when there are multiple servers
in a cluster or a storage problem for a server that might lose state. in a cluster or a storage problem for a server that might lose state.
Stateless reset specifically exists to handle the case where state is Stateless reset specifically exists to handle the case where state is
lost, so this approach is suboptimal. lost, so this approach is suboptimal.
A single static key can be used across all connections to the same A single static key can be used across all connections to the same
skipping to change at page 39, line 34 skipping to change at page 44, line 7
Note that Stateless Reset messages do not have any cryptographic Note that Stateless Reset messages do not have any cryptographic
protection. protection.
8. Frame Types and Formats 8. Frame Types and Formats
As described in Section 6, Regular packets contain one or more As described in Section 6, Regular packets contain one or more
frames. We now describe the various QUIC frame types that can be frames. We now describe the various QUIC frame types that can be
present in a Regular packet. The use of these frames and various present in a Regular packet. The use of these frames and various
frame header bits are described in subsequent sections. frame header bits are described in subsequent sections.
8.1. PADDING Frame 8.1. Variable-Length Integer Encoding
QUIC frames use a common variable-length encoding for all non-
negative integer values. This encoding ensures that smaller integer
values need fewer octets to encode.
The QUIC variable-length integer encoding reserves the two most
significant bits of the first octet to encode the base 2 logarithm of
the integer encoding length in octets. The integer value is encoded
on the remaining bits, in network byte order.
This means that integers are encoded on 1, 2, 4, or 8 octets and can
encode 6, 14, 30, or 62 bit values respectively. Table 4 summarizes
the encoding properties.
+------+--------+-------------+-----------------------+
| 2Bit | Length | Usable Bits | Range |
+------+--------+-------------+-----------------------+
| 00 | 1 | 6 | 0-63 |
| | | | |
| 01 | 2 | 14 | 0-16383 |
| | | | |
| 10 | 4 | 30 | 0-1073741823 |
| | | | |
| 11 | 8 | 62 | 0-4611686018427387903 |
+------+--------+-------------+-----------------------+
Table 4: Summary of Integer Encodings
For example, the eight octet sequence c2 19 7c 5e ff 14 e8 8c (in
hexadecimal) decodes to the decimal value 151288809941952652; the
four octet sequence 9d 7f 3e 7d decodes to 494878333; the two octet
sequence 7b bd decodes to 15293; and the single octet 25 decodes to
37 (as does the two octet sequence 40 25).
Error codes (Section 12.3) are described using integers, but do not
use this encoding.
8.2. PADDING Frame
The PADDING frame (type=0x00) has no semantic value. PADDING frames The PADDING frame (type=0x00) has no semantic value. PADDING frames
can be used to increase the size of a packet. Padding can be used to can be used to increase the size of a packet. Padding can be used to
increase an initial client packet to the minimum required size, or to increase an initial client packet to the minimum required size, or to
provide protection against traffic analysis for protected packets. provide protection against traffic analysis for protected packets.
A PADDING frame has no content. That is, a PADDING frame consists of A PADDING frame has no content. That is, a PADDING frame consists of
the single octet that identifies the frame as a PADDING frame. the single octet that identifies the frame as a PADDING frame.
8.2. RST_STREAM Frame 8.3. RST_STREAM Frame
An endpoint may use a RST_STREAM frame (type=0x01) to abruptly An endpoint may use a RST_STREAM frame (type=0x01) to abruptly
terminate a stream. terminate a stream.
After sending a RST_STREAM, an endpoint ceases transmission and After sending a RST_STREAM, an endpoint ceases transmission and
retransmission of STREAM frames on the identified stream. A receiver retransmission of STREAM frames on the identified stream. A receiver
of RST_STREAM can discard any data that it already received on that of RST_STREAM can discard any data that it already received on that
stream. stream.
The RST_STREAM frame is as follows: The RST_STREAM frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (32) | | Stream ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Application Error Code (16) | | Application Error Code (16) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | Final Offset (i) ...
+ Final Offset (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are: The fields are:
Stream ID: The 32-bit Stream ID of the stream being terminated. Stream ID: A variable-length integer encoding of the Stream ID of
the stream being terminated.
Application Protocol Error Code: A 16-bit application protocol error Application Protocol Error Code: A 16-bit application protocol error
code (see Section 12.4) which indicates why the stream is being code (see Section 12.4) which indicates why the stream is being
closed. closed.
Final Offset: A 64-bit unsigned integer indicating the absolute byte Final Offset: A variable-length integer indicating the absolute byte
offset of the end of data written on this stream by the RST_STREAM offset of the end of data written on this stream by the RST_STREAM
sender. sender.
8.3. CONNECTION_CLOSE frame 8.4. CONNECTION_CLOSE frame
An endpoint sends a CONNECTION_CLOSE frame (type=0x02) to notify its An endpoint sends a CONNECTION_CLOSE frame (type=0x02) to notify its
peer that the connection is being closed. CONNECTION_CLOSE is used peer that the connection is being closed. CONNECTION_CLOSE is used
to signal errors at the QUIC layer, or the absence of errors (with to signal errors at the QUIC layer, or the absence of errors (with
the NO_ERROR code). the NO_ERROR code).
If there are open streams that haven't been explicitly closed, they If there are open streams that haven't been explicitly closed, they
are implicitly closed when the connection is closed. are implicitly closed when the connection is closed.
The CONNECTION_CLOSE frame is as follows: The CONNECTION_CLOSE frame is as follows:
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 (16) | | Error Code (16) | Reason Phrase Length (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reason Phrase (*) ... | Reason Phrase (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields of a CONNECTION_CLOSE frame are as follows: The fields of a CONNECTION_CLOSE frame are as follows:
Error Code: A 16-bit error code which indicates the reason for Error Code: A 16-bit error code which indicates the reason for
closing this connection. CONNECTION_CLOSE uses codes from the closing this connection. CONNECTION_CLOSE uses codes from the
space defined in Section 12.3 (APPLICATION_CLOSE uses codes from space defined in Section 12.3 (APPLICATION_CLOSE uses codes from
the application protocol error code space, see Section 12.4). the application protocol error code space, see Section 12.4).
Reason Phrase Length: A 16-bit unsigned number specifying the length Reason Phrase Length: A variable-length integer specifying the
of the reason phrase in bytes. Note that a CONNECTION_CLOSE frame length of the reason phrase in bytes. Note that a
cannot be split between packets, so in practice any limits on CONNECTION_CLOSE frame cannot be split between packets, so in
packet size will also limit the space available for a reason practice any limits on packet size will also limit the space
phrase. available for a reason phrase.
Reason Phrase: A human-readable explanation for why the connection Reason Phrase: A human-readable explanation for why the connection
was closed. This can be zero length if the sender chooses to not was closed. This can be zero length if the sender chooses to not
give details beyond the Error Code. This SHOULD be a UTF-8 give details beyond the Error Code. This SHOULD be a UTF-8
encoded string [RFC3629]. encoded string [RFC3629].
8.4. APPLICATION_CLOSE frame 8.5. APPLICATION_CLOSE frame
An APPLICATION_CLOSE frame (type=0x03) uses the same format as the An APPLICATION_CLOSE frame (type=0x03) uses the same format as the
CONNECTION_CLOSE frame (Section 8.3), except that it uses error codes CONNECTION_CLOSE frame (Section 8.4), except that it uses error codes
from the application protocol error code space (Section 12.4) instead from the application protocol error code space (Section 12.4) instead
of the transport error code space. of the transport error code space.
Other than the error code space, the format and semantics of the Other than the error code space, the format and semantics of the
APPLICATION_CLOSE frame are identical to the CONNECTION_CLOSE frame. APPLICATION_CLOSE frame are identical to the CONNECTION_CLOSE frame.
8.5. MAX_DATA Frame 8.6. MAX_DATA Frame
The MAX_DATA frame (type=0x04) is used in flow control to inform the The MAX_DATA frame (type=0x04) is used in flow control to inform the
peer of the maximum amount of data that can be sent on the connection peer of the maximum amount of data that can be sent on the connection
as a whole. as a whole.
The frame is as follows: The frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | Maximum Data (i) ...
+ Maximum Data (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields in the MAX_DATA frame are as follows: The fields in the MAX_DATA frame are as follows:
Maximum Data: A 64-bit unsigned 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 1024 octets. That is, the updated connection-level data limit of octets.
is determined by multiplying the encoded value by 1024.
All data sent in STREAM frames counts toward this limit, with the All data sent in STREAM frames counts toward this limit, with the
exception of data on stream 0. The sum of the largest received exception of data on stream 0. The sum of the largest received
offsets on all streams - including closed streams, but excluding offsets on all streams - including streams in terminal states, but
stream 0 - MUST NOT exceed the value advertised by a receiver. An excluding stream 0 - MUST NOT exceed the value advertised by a
endpoint MUST terminate a connection with a receiver. An endpoint MUST terminate a connection with a
QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA error if it receives more QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA error if it receives more
data than the maximum data value that it has sent, unless this is a data than the maximum data value that it has sent, unless this is a
result of a change in the initial limits (see Section 7.4.2). result of a change in the initial limits (see Section 7.4.2).
8.6. MAX_STREAM_DATA Frame 8.7. 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.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (32) | | Stream ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | Maximum Stream Data (i) ...
+ Maximum Stream Data (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields in the MAX_STREAM_DATA frame are as follows: The fields in the MAX_STREAM_DATA frame are as follows:
Stream ID: The stream ID of the stream that is affected. Stream ID: The stream ID of the stream that is affected encoded as a
variable-length integer.
Maximum Stream Data: A 64-bit unsigned integer indicating the Maximum Stream Data: A variable-length integer indicating the
maximum amount of data that can be sent on the identified stream, maximum amount of data that can be sent on the identified stream,
in units of octets. in units of octets.
When counting data toward this limit, an endpoint accounts for the When counting data toward this limit, an endpoint accounts for the
largest received offset of data that is sent or received on the largest received offset of data that is sent or received on the
stream. Loss or reordering can mean that the largest received offset stream. Loss or reordering can mean that the largest received offset
on a stream can be greater than the total size of data received on on a stream can be greater than the total size of data received on
that stream. Receiving STREAM frames might not increase the largest that stream. Receiving STREAM frames might not increase the largest
received offset. received offset.
The data sent on a stream MUST NOT exceed the largest maximum stream The data sent on a stream MUST NOT exceed the largest maximum stream
data value advertised by the receiver. An endpoint MUST terminate a data value advertised by the receiver. An endpoint MUST terminate a
connection with a FLOW_CONTROL_ERROR error if it receives more data connection with a FLOW_CONTROL_ERROR error if it receives more data
than the largest maximum stream data that it has sent for the than the largest maximum stream data that it has sent for the
affected stream, unless this is a result of a change in the initial affected stream, unless this is a result of a change in the initial
limits (see Section 7.4.2). limits (see Section 7.4.2).
8.7. MAX_STREAM_ID Frame 8.8. MAX_STREAM_ID Frame
The MAX_STREAM_ID frame (type=0x06) informs the peer of the maximum The MAX_STREAM_ID frame (type=0x06) informs the peer of the maximum
stream ID that they are permitted to open. stream ID that they are permitted to open.
The frame is as follows: The frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Stream ID (32) | | Maximum Stream ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields in the MAX_STREAM_ID frame are as follows: The fields in the MAX_STREAM_ID frame are as follows:
Maximum Stream ID: ID of the maximum peer-initiated stream ID for Maximum Stream ID: ID of the maximum unidirectional or bidirectional
the connection. peer-initiated stream ID for the connection encoded as a variable-
length integer. The limit applies to unidirectional steams if the
second least signification bit of the stream ID is 1, and applies
to bidirectional streams if it is 0.
Loss or reordering can mean that a MAX_STREAM_ID frame can be Loss or reordering can mean that a MAX_STREAM_ID frame can be
received which states a lower stream limit than the client has received which states a lower stream limit than the client has
previously received. MAX_STREAM_ID frames which do not increase the previously received. MAX_STREAM_ID frames which do not increase the
maximum stream ID MUST be ignored. maximum stream ID MUST be ignored.
A peer MUST NOT initiate a stream with a higher stream ID than the A peer MUST NOT initiate a stream with a higher stream ID than the
greatest maximum stream ID it has received. An endpoint MUST greatest maximum stream ID it has received. An endpoint MUST
terminate a connection with a STREAM_ID_ERROR error if a peer terminate a connection with a STREAM_ID_ERROR error if a peer
initiates a stream with a higher stream ID than it has sent, unless initiates a stream with a higher stream ID than it has sent, unless
this is a result of a change in the initial limits (see this is a result of a change in the initial limits (see
Section 7.4.2). Section 7.4.2).
8.8. PING frame 8.9. 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.
contains no additional fields. The receiver of a PING frame simply
needs to acknowledge the packet containing this frame.
A PING frame has no additional fields. The PING frame contains a variable-length payload.
The PING frame can be used to keep a connection alive when an 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length(8) | Data (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Length: This 8-bit value describes the length of the Data field.
Data: This variable-length field contains arbitrary data.
A PING frame with an empty Data field causes the packet containing it
to be acknowledged as normal. No other action is required of the
recipient.
An empty PING frame can be used to keep a connection alive when an
application or application protocol wishes to prevent the connection application or application protocol wishes to prevent the connection
from timing out. An application protocol SHOULD provide guidance from timing out. An application protocol SHOULD provide guidance
about the conditions under which generating a PING is recommended. about the conditions under which generating a PING is recommended.
This guidance SHOULD indicate whether it is the client or the server This guidance SHOULD indicate whether it is the client or the server
that is expected to send the PING. Having both endpoints send PING that is expected to send the PING. Having both endpoints send PING
frames without coordination can produce an excessive number of frames without coordination can produce an excessive number of
packets and poor performance. packets and poor performance.
If the Data field is not empty, the recipient of this frame MUST
generate a PONG frame (Section 8.15) containing the same Data. A
PING frame with data is not appropriate for use in keeping a
connection alive, because the PONG frame elicits an acknowledgement,
causing the sender of the original PING to send two packets.
A connection will time out if no packets are sent or received for a A connection will time out if no packets are sent or received for a
period longer than the time specified in the idle_timeout transport period longer than the time specified in the idle_timeout transport
parameter (see Section 7.8). However, state in middleboxes might parameter (see Section 7.9). However, state in middleboxes might
time out earlier than that. Though REQ-5 in [RFC4787] recommends a 2 time out earlier than that. Though REQ-5 in [RFC4787] recommends a 2
minute timeout interval, experience shows that sending packets every minute timeout interval, experience shows that sending packets every
15 to 30 seconds is necessary to prevent the majority of middleboxes 15 to 30 seconds is necessary to prevent the majority of middleboxes
from losing state for UDP flows. from losing state for UDP flows.
8.9. BLOCKED Frame 8.10. BLOCKED Frame
A sender sends a BLOCKED frame (type=0x08) when it wishes to send A sender SHOULD send a BLOCKED frame (type=0x08) when it wishes to
data, but is unable to due to connection-level flow control (see send data, but is unable to due to connection-level flow control (see
Section 11.2.1). BLOCKED frames can be used as input to tuning of Section 11.2.1). BLOCKED frames can be used as input to tuning of
flow control algorithms (see Section 11.1.2). flow control algorithms (see Section 11.1.2).
The BLOCKED frame does not contain a payload. The BLOCKED frame is as follows:
8.10. STREAM_BLOCKED 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Offset (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A sender sends a STREAM_BLOCKED frame (type=0x09) when it wishes to The BLOCKED frame contains a single field.
send data, but is unable to due to stream-level flow control. This
frame is analogous to BLOCKED (Section 8.9). Offset: A variable-length integer indicating the connection-level
offset at which the blocking occurred.
8.11. STREAM_BLOCKED Frame
A sender SHOULD send a STREAM_BLOCKED frame (type=0x09) when it
wishes to send data, but is unable to due to stream-level flow
control. This frame is analogous to BLOCKED (Section 8.10).
The STREAM_BLOCKED frame is as follows: The STREAM_BLOCKED frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (32) | | Stream ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Offset (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The STREAM_BLOCKED frame contains a single field: The STREAM_BLOCKED frame contains two fields:
Stream ID: A 32-bit unsigned number indicating the stream which is Stream ID: A variable-length integer indicating the stream which is
flow control blocked. flow control blocked.
8.11. STREAM_ID_BLOCKED Frame Offset: A variable-length integer indicating the offset of the
stream at which the blocking occurred.
8.12. STREAM_ID_BLOCKED Frame
A sender MAY send a STREAM_ID_BLOCKED frame (type=0x0a) when it A sender MAY send a STREAM_ID_BLOCKED frame (type=0x0a) when it
wishes to open a stream, but is unable to due to the maximum stream wishes to open a stream, but is unable to due to the maximum stream
ID limit set by its peer (see Section 8.7). This does not open the ID limit set by its peer (see Section 8.8). This does not open the
stream, but informs the peer that a new stream was needed, but the stream, but informs the peer that a new stream was needed, but the
stream limit prevented the creation of the stream. stream limit prevented the creation of the stream.
The STREAM_ID_BLOCKED frame does not contain a payload. The STREAM_ID_BLOCKED frame is as follows:
8.12. NEW_CONNECTION_ID 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The STREAM_ID_BLOCKED frame contains a single field.
Stream ID: A variable-length integer indicating the highest stream
ID that the sender was permitted to open.
8.13. NEW_CONNECTION_ID Frame
A server sends a NEW_CONNECTION_ID frame (type=0x0b) to provide the A server sends a NEW_CONNECTION_ID frame (type=0x0b) to provide the
client with alternative connection IDs that can be used to break client with alternative connection IDs that can be used to break
linkability when migrating connections (see Section 7.7.1). linkability when migrating connections (see Section 7.7.1).
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 (16) | | Sequence (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Connection ID (64) + + Connection ID (64) +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ Stateless Reset Token (128) + + Stateless Reset Token (128) +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are: The fields are:
Sequence: A 16-bit sequence number. This value starts at 0 and Sequence: A variable-length integer. This value starts at 0 and
increases by 1 for each connection ID that is provided by the increases by 1 for each connection ID that is provided by the
server. The sequence value can wrap; the value 65535 is followed server. The connection ID that is assigned during the handshake
by 0. When wrapping the sequence field, the server MUST ensure is assumed to have a sequence of -1. That is, the value selected
that a value with the same sequence has been received and during the handshake comes immediately before the first value that
acknowledged by the client. The connection ID that is assigned a server can send.
during the handshake is assumed to have a sequence of 65535.
Connection ID: A 64-bit connection ID. Connection ID: A 64-bit connection ID.
Stateless Reset Token: A 128-bit value that will be used to for a Stateless Reset Token: A 128-bit value that will be used to for a
stateless reset when the associated connection ID is used (see stateless reset when the associated connection ID is used (see
Section 7.8.4). Section 7.9.4).
8.13. STOP_SENDING Frame 8.14. STOP_SENDING Frame
An endpoint may use a STOP_SENDING frame (type=0x0c) to communicate An endpoint may use a STOP_SENDING frame (type=0x0c) to communicate
that incoming data is being discarded on receipt at application that incoming data is being discarded on receipt at application
request. This signals a peer to abruptly terminate transmission on a request. This signals a peer to abruptly terminate transmission on a
stream. stream.
The STOP_SENDING frame is as follows: The STOP_SENDING frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (32) | | Stream ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Application Error Code (16) | | Application Error Code (16) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are: The fields are:
Stream ID: The 32-bit Stream ID of the stream being ignored. Stream ID: A variable-length integer carrying the Stream ID of the
stream being ignored.
Application Error Code: A 16-bit, application-specified reason the Application Error Code: A 16-bit, application-specified reason the
sender is ignoring the stream (see Section 12.4). sender is ignoring the stream (see Section 12.4).
8.14. ACK Frame 8.15. PONG Frame
Receivers send ACK frames to inform senders which packets they have The PONG frame (type=0x0d) is sent in response to a PING frame that
received and processed, as well as which packets are considered contains data. Its format is identical to the PING frame
missing. The ACK frame contains between 1 and 256 ACK blocks. ACK (Section 8.9).
blocks are ranges of acknowledged packets. Implementations MUST NOT
generate packets that only contain ACK frames in response to packets
which only contain ACK frames. However, they SHOULD acknowledge
packets containing only ACK frames when sending ACK frames in
response to other packets.
To limit ACK blocks to those that have not yet been received by the An endpoint that receives an unsolicited PONG frame - that is, a PONG
sender, the receiver SHOULD track which ACK frames have been frame containing a payload that is empty MUST generate a connection
acknowledged by its peer. Once an ACK frame has been acknowledged, error of type FRAME_ERROR, indicating the PONG frame (that is,
the packets it acknowledges SHOULD NOT be acknowledged again. 0x10d). If the content of a PONG frame does not match the content of
a PING frame previously sent by the endpoint, the endpoint MAY
generate a connection error of type UNSOLICITED_PONG.
A receiver that is only sending ACK frames will not receive 8.16. ACK Frame
acknowledgments for its packets. Sending an occasional MAX_DATA or
MAX_STREAM_DATA frame as data is received will ensure that
acknowledgements are generated by a peer. Otherwise, an endpoint MAY
send a PING frame once per RTT to solicit an acknowledgment.
To limit receiver state or the size of ACK frames, a receiver MAY Receivers send ACK frames (type=0xe) to inform senders which packets
limit the number of ACK blocks it sends. A receiver can do this even they have received and processed. A sent packet that has never been
without receiving acknowledgment of its ACK frames, with the acknowledged is missing. The ACK frame contains any number of ACK
knowledge this could cause the sender to unnecessarily retransmit blocks. ACK blocks are ranges of acknowledged packets.
some data. When this is necessary, the receiver SHOULD acknowledge
newly received packets and stop acknowledging packets received in the
past.
Unlike TCP SACKs, QUIC ACK blocks are irrevocable. Once a packet has Unlike TCP SACKs, QUIC acknowledgements are irrevocable. Once a
been acknowledged, even if it does not appear in a future ACK frame, packet has been acknowledged, even if it does not appear in a future
it remains acknowledged. ACK frame, it remains acknowledged.
A client MUST NOT acknowledge Version Negotiation or Server Stateless A client MUST NOT acknowledge Version Negotiation or Retry packets.
Retry packets. These packet types contain packet numbers selected by These packet types contain packet numbers selected by the client, not
the client, not the server. the server.
A sender MAY intentionally skip packet numbers to introduce entropy A sender MAY intentionally skip packet numbers to introduce entropy
into the connection, to avoid opportunistic acknowledgement attacks. into the connection, to avoid opportunistic acknowledgement attacks.
The sender SHOULD close the connection if an unsent packet number is The sender SHOULD close the connection if an unsent packet number is
acknowledged. The format of the ACK frame is efficient at expressing acknowledged. The format of the ACK frame is efficient at expressing
blocks of missing packets; skipping packet numbers between 1 and 255 even long blocks of missing packets, allowing for large,
effectively provides up to 8 bits of efficient entropy on demand, unpredictable gaps.
which should be adequate protection against most opportunistic
acknowledgement attacks.
The type byte for a ACK frame contains embedded flags, and is
formatted as "101NLLMM". These bits are parsed as follows:
o The first three bits must be set to 101 indicating that this is an
ACK frame.
o The "N" bit indicates whether the frame contains a Num Blocks
field.
o The two "LL" bits encode the length of the Largest Acknowledged
field. The values 00, 01, 02, and 03 indicate lengths of 8, 16,
32, and 64 bits respectively.
o The two "MM" bits encode the length of the ACK Block Length
fields. The values 00, 01, 02, and 03 indicate lengths of 8, 16,
32, and 64 bits respectively.
An ACK frame is shown below. An ACK frame is shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|[Num Blocks(8)]| | Largest Acknowledged (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Largest Acknowledged (8/16/32/64) ... | ACK Delay (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Delay (16) | | ACK Block Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Block Section (*) ... | ACK Blocks (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: ACK Frame Format Figure 7: ACK Frame Format
The fields in the ACK frame are as follows: The fields in the ACK frame are as follows:
Num Blocks (opt): An optional 8-bit unsigned value specifying the Largest Acknowledged: A variable-length integer representing the
number of additional ACK blocks (besides the required First ACK largest packet number the peer is acknowledging; this is usually
Block) in this ACK frame. Only present if the 'N' flag bit is 1. the largest packet number that the peer has received prior to
generating the ACK frame.
Largest Acknowledged: A variable-sized unsigned value representing ACK Delay: A variable-length integer including the time in
the largest packet number the peer is acknowledging in this packet microseconds that the largest acknowledged packet, as indicated in
(typically the largest that the peer has seen thus far.) 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
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 frame. The "ack_delay_exponent" defaults to 3, or a
multiplier of 8 (see Section 7.4.1). Scaling in this fashion
allows for a larger range of values with a shorter encoding at the
cost of lower resolution.
ACK Delay: The time from when the largest acknowledged packet, as ACK Block Count: The number of Additional ACK Block (and Gap) fields
indicated in the Largest Acknowledged field, was received by this after the First ACK Block.
peer to when this ACK was sent.
ACK Block Section: Contains one or more blocks of packet numbers ACK Blocks: Contains one or more blocks of packet numbers which have
which have been successfully received, see Section 8.14.1. been successfully received, see Section 8.16.1.
8.14.1. ACK Block Section 8.16.1. ACK Block Section
The ACK Block Section contains between one and 256 blocks of packet The ACK Block Section consists of alternating Gap and ACK Block
numbers which have been successfully received. If the Num Blocks fields in descending packet number order. A First Ack Block field is
field is absent, only the First ACK Block length is present in this followed by a variable number of alternating Gap and Additional ACK
section. Otherwise, the Num Blocks field indicates how many Blocks. The number of Gap and Additional ACK Block fields is
additional blocks follow the First ACK Block Length field. determined by the ACK Block Count field.
Gap and ACK Block fields use a relative integer encoding for
efficiency. Though each encoded value is positive, the values are
subtracted, so that each ACK Block describes progressively lower-
numbered packets. As long as contiguous ranges of packets are small,
the variable-length integer encoding ensures that each range can be
expressed in a small number of octets.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| First ACK Block Length (8/16/32/64) ... | First ACK Block (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Gap 1 (8)] | [ACK Block 1 Length (8/16/32/64)] ... | Gap (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Gap 2 (8)] | [ACK Block 2 Length (8/16/32/64)] ... | Additional ACK Block (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... | Gap (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Gap N (8)] | [ACK Block N Length (8/16/32/64)] ... | Additional ACK Block (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Gap (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Additional ACK Block (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: ACK Block Section Figure 8: ACK Block Section
Each ACK Block acknowledges a contiguous range of packets by
indicating the number of acknowledged packets that precede the
largest packet number in that block. A value of zero indicates that
only the largest packet number is acknowledged. Larger ACK Block
values indicate a larger range, with corresponding lower values for
the smallest packet number in the range. Thus, given a largest
packet number for the ACK, the smallest value is determined by the
formula:
smallest = largest - ack_block
The range of packets that are acknowledged by the ACK block include
the range from the smallest packet number to the largest, inclusive.
The largest value for the First ACK Block is determined by the
Largest Acknowledged field; the largest for Additional ACK Blocks is
determined by cumulatively subtracting the size of all preceding ACK
Blocks and Gaps.
Each Gap indicates a range of packets that are not being
acknowledged. The number of packets in the gap is one higher than
the encoded value of the Gap Field.
The value of the Gap field establishes the largest packet number
value for the ACK block that follows the gap using the following
formula:
largest = previous_smallest - gap - 2
If the calculated value for largest or smallest packet number for any
ACK Block is negative, an endpoint MUST generate a connection error
of type FRAME_ERROR indicating an error in an ACK frame (that is,
0x10d).
The fields in the ACK Block Section are: The fields in the ACK Block Section are:
First ACK Block Length: An unsigned packet number delta that First ACK Block: A variable-length integer indicating the number of
indicates the number of contiguous additional packets being contiguous packets preceding the Largest Acknowledged that are
acknowledged starting at the Largest Acknowledged. being acknowledged.
Gap To Next Block (opt, repeated): An unsigned number specifying the Gap (repeated): A variable-length integer indicating the number of
number of contiguous missing packets from the end of the previous contiguous unacknowledged packets preceding the packet number one
ACK block to the start of the next. Repeated "Num Blocks" times. lower than the smallest in the preceding ACK Block.
ACK Block Length (opt, repeated): An unsigned packet number delta ACK Block (repeated): A variable-length integer indicating the
that indicates the number of contiguous packets being acknowledged number of contiguous acknowledged packets preceding the largest
starting after the end of the previous gap. Repeated "Num Blocks" packet number, as determined by the preceding Gap.
times.
8.14.1.1. Time Format 8.16.2. Sending ACK Frames
DISCUSS_AND_REPLACE: Perhaps make this format simpler. Implementations MUST NOT generate packets that only contain ACK
frames in response to packets which only contain ACK frames.
However, they MUST acknowledge packets containing only ACK frames
when sending ACK frames in response to other packets.
Implementations MUST NOT send more than one ACK frame per received
packet that contains frames other than ACK frames. Packets
containing non-ACK frames MUST be acknowledged immediately or when a
delayed ack timer expires.
The time format used in the ACK frame above is a 16-bit unsigned To limit ACK blocks to those that have not yet been received by the
float with 11 explicit bits of mantissa and 5 bits of explicit sender, the receiver SHOULD track which ACK frames have been
exponent, specifying time in microseconds. The bit format is loosely acknowledged by its peer. Once an ACK frame has been acknowledged,
modeled after IEEE 754. For example, 1 microsecond is represented as the packets it acknowledges SHOULD NOT be acknowledged again.
0x1, which has an exponent of zero, presented in the 5 high order
bits, and mantissa of 1, presented in the 11 low order bits. When
the explicit exponent is greater than zero, an implicit high-order
12th bit of 1 is assumed in the mantissa. For example, a floating
value of 0x800 has an explicit exponent of 1, as well as an explicit
mantissa of 0, but then has an effective mantissa of 4096 (12th bit
is assumed to be 1). Additionally, the actual exponent is one-less
than the explicit exponent, and the value represents 4096
microseconds. Any values larger than the representable range are
clamped to 0xFFFF.
8.14.2. ACK Frames and Packet Protection A receiver that is only sending ACK frames will not receive
acknowledgments for its packets. Sending an occasional MAX_DATA or
MAX_STREAM_DATA frame as data is received will ensure that
acknowledgements are generated by a peer. Otherwise, an endpoint MAY
send a PING frame once per RTT to solicit an acknowledgment.
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
without receiving acknowledgment of its ACK frames, with the
knowledge this could cause the sender to unnecessarily retransmit
some data. Standard QUIC [QUIC-RECOVERY] algorithms declare packets
lost after sufficiently newer packets are acknowledged. Therefore,
the receiver SHOULD repeatedly acknowledge newly received packets in
preference to packets received in the past.
8.16.3. ACK Frames and Packet Protection
ACK frames that acknowledge protected packets MUST be carried in a ACK frames that acknowledge protected packets MUST be carried in a
packet that has an equivalent or greater level of packet protection. packet that has an equivalent or greater level of packet protection.
Packets that are protected with 1-RTT keys MUST be acknowledged in Packets that are protected with 1-RTT keys MUST be acknowledged in
packets that are also protected with 1-RTT keys. packets that are also protected with 1-RTT keys.
A packet that is not protected and claims to acknowledge a packet A packet that is not protected and claims to acknowledge a packet
number that was sent with packet protection is not valid. An number that was sent with packet protection is not valid. An
unprotected packet that carries acknowledgments for protected packets unprotected packet that carries acknowledgments for protected packets
skipping to change at page 51, line 5 skipping to change at page 58, line 5
protection keys. protection keys.
For instance, a server acknowledges a TLS ClientHello in the packet For instance, a server acknowledges a TLS ClientHello in the packet
that carries the TLS ServerHello; similarly, a client can acknowledge that carries the TLS ServerHello; similarly, a client can acknowledge
a TLS HelloRetryRequest in the packet containing a second TLS a TLS HelloRetryRequest in the packet containing a second TLS
ClientHello. The complete set of server handshake messages (TLS ClientHello. The complete set of server handshake messages (TLS
ServerHello through to Finished) might be acknowledged by a client in ServerHello through to Finished) might be acknowledged by a client in
protected packets, because it is certain that the server is able to protected packets, because it is certain that the server is able to
decipher the packet. decipher the packet.
8.15. STREAM Frame 8.17. STREAM Frames
STREAM frames implicitly create a stream and carry stream data. The STREAM frames implicitly create a stream and carry stream data. The
type byte for a STREAM frame contains embedded flags, and is STREAM frame takes the form 0b00010XXX (or the set of values from
formatted as "11FSSOOD". These bits are parsed as follows: 0x10 to 0x17). The value of the three low-order bits of the frame
type determine the fields that are present in the frame.
o The first two bits must be set to 11, indicating that this is a
STREAM frame.
o "F" is the FIN bit, which is used for stream termination.
o The "SS" bits encode the length of the Stream ID header field. o The FIN bit (0x01) of the frame type is set only on frames that
The values 00, 01, 02, and 03 indicate lengths of 8, 16, 24, and contain the final offset of the stream. Setting this bit
32 bits long respectively. indicates that the frame marks the end of the stream.
o The "OO" bits encode the length of the Offset header field. The o The LEN bit (0x02) in the frame type is set to indicate that there
values 00, 01, 02, and 03 indicate lengths of 0, 16, 32, and 64 is a Length field present. If this bit is set to 0, the Length
bits long respectively. field is absent and the Stream Data field extends to the end of
the packet. If this bit is set to 1, the Length field is present.
o The "D" bit indicates whether a Data Length field is present in o The OFF bit (0x04) in the frame type is set to indicate that there
the STREAM header. When set to 0, this field indicates that the is an Offset field present. When set to 1, the Offset field is
Stream Data field extends to the end of the packet. When set to present; when set to 0, the Offset field is absent and the Stream
1, this field indicates that Data Length field contains the length Data starts at an offset of 0 (that is, the frame contains the
(in bytes) of the Stream Data field. The option to omit the first octets of the stream, or the end of a stream that includes
length should only be used when the packet is a "full-sized" no data).
packet, to avoid the risk of corruption via padding.
A STREAM frame is shown below. A STREAM frame is shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (8/16/24/32) ... | Stream ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Offset (0/16/32/64) ... | [Offset (i)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Data Length (16)] | Stream Data (*) ... | [Length (i)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream Data (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: STREAM Frame Format Figure 9: STREAM Frame Format
The STREAM frame contains the following fields: The STREAM frame contains the following fields:
Stream ID: The stream ID of the stream (see Section 10.1). Stream ID: A variable-length integer indicating the stream ID of the
stream (see Section 10.1).
Offset: A variable-sized unsigned number specifying the byte offset Offset: A variable-length integer specifying the byte offset in the
in the stream for the data in this STREAM frame. When the offset stream for the data in this STREAM frame. This field is present
length is 0, the offset is 0. The first byte in the stream has an when the OFF bit is set to 1. When the Offset field is absent,
offset of 0. The largest offset delivered on a stream - the sum the offset is 0.
of the re-constructed offset and data length - MUST be less than
2^64.
Data Length: An optional 16-bit unsigned number specifying the Length: A variable-length integer specifying the length of the
length of the Stream Data field in this STREAM frame. This field Stream Data field in this STREAM frame. This field is present
is present when the "D" bit is set to 1. when the LEN bit is set to 1. When the LEN bit is set to 0, the
Stream Data field consumes all the remaining octets in the packet.
Stream Data: The bytes from the designated stream to be delivered. Stream Data: The bytes from the designated stream to be delivered.
A stream frame's Stream Data MUST NOT be empty, unless the FIN bit is A stream frame's Stream Data MUST NOT be empty, unless the FIN bit is
set. When the FIN flag is sent on an empty STREAM frame, the offset set. When the FIN flag is sent on an empty STREAM frame, the offset
in the STREAM frame is the offset of the next byte that would be in the STREAM frame is the offset of the next byte that would be
sent. sent.
The first byte in the stream has an offset of 0. The largest offset
delivered on a stream - the sum of the re-constructed offset and data
length - MUST be less than 2^62.
Stream multiplexing is achieved by interleaving STREAM frames from Stream multiplexing is achieved by interleaving STREAM frames from
multiple streams into one or more QUIC packets. A single QUIC packet multiple streams into one or more QUIC packets. A single QUIC packet
can include multiple STREAM frames from one or more streams. can include multiple STREAM frames from one or more streams.
Implementation note: One of the benefits of QUIC is avoidance of Implementation note: One of the benefits of QUIC is avoidance of
head-of-line blocking across multiple streams. When a packet loss head-of-line blocking across multiple streams. When a packet loss
occurs, only streams with data in that packet are blocked waiting for occurs, only streams with data in that packet are blocked waiting for
a retransmission to be received, while other streams can continue a retransmission to be received, while other streams can continue
making progress. Note that when data from multiple streams is making progress. Note that when data from multiple streams is
bundled into a single QUIC packet, loss of that packet blocks all bundled into a single QUIC packet, loss of that packet blocks all
skipping to change at page 54, line 19 skipping to change at page 61, line 19
necessary: necessary:
o All application data sent in STREAM frames MUST be retransmitted, o All application data sent in STREAM frames MUST be retransmitted,
unless the endpoint has sent a RST_STREAM for that stream. When unless the endpoint has sent a RST_STREAM for that stream. When
an endpoint sends a RST_STREAM frame, data outstanding on that an endpoint sends a RST_STREAM frame, data outstanding on that
stream SHOULD NOT be retransmitted, since subsequent data on this stream SHOULD NOT be retransmitted, since subsequent data on this
stream is expected to not be delivered by the receiver. stream is expected to not be delivered by the receiver.
o ACK and PADDING frames MUST NOT be retransmitted. ACK frames o ACK and PADDING frames MUST NOT be retransmitted. ACK frames
containing updated information will be sent as described in containing updated information will be sent as described in
Section 8.14. Section 8.16.
o STOP_SENDING frames MUST be retransmitted, unless the stream has o STOP_SENDING frames MUST be retransmitted until the receive stream
become closed in the appropriate direction. See Section 10.3. enters either a "Data Recvd" or "Reset Recvd" state. See
Section 10.3.
o The most recent MAX_STREAM_DATA frame for a stream MUST be o The most recent MAX_STREAM_DATA frame for a stream MUST be
retransmitted. Any previous unacknowledged MAX_STREAM_DATA frame retransmitted until the receive stream enters a "Size Known"
for the same stream SHOULD NOT be retransmitted since a newer state. Any previous unacknowledged MAX_STREAM_DATA frame for the
same stream SHOULD NOT be retransmitted since a newer
MAX_STREAM_DATA frame for a stream obviates the need for MAX_STREAM_DATA frame for a stream obviates the need for
delivering older ones. Similarly, the most recent MAX_DATA frame delivering older ones. Similarly, the most recent MAX_DATA frame
MUST be retransmitted; previous unacknowledged ones SHOULD NOT be MUST be retransmitted; previous unacknowledged ones SHOULD NOT be
retransmitted. retransmitted.
o BLOCKED, STREAM_BLOCKED, and STREAM_ID_BLOCKED frames SHOULD be
retransmitted if the sender is still blocked on the same limit.
If the limit has been increased since the frame was originally
sent, the frame SHOULD NOT be retransmitted.
o All other frames MUST be retransmitted. o All other frames MUST be retransmitted.
Upon detecting losses, a sender MUST take appropriate congestion Upon detecting losses, a sender MUST take appropriate congestion
control action. The details of loss detection and congestion control control action. The details of loss detection and congestion control
are described in [QUIC-RECOVERY]. are described in [QUIC-RECOVERY].
A packet MUST NOT be acknowledged until packet protection has been A packet MUST NOT be acknowledged until packet protection has been
successfully removed and all frames contained in the packet have been successfully removed and all frames contained in the packet have been
processed. For STREAM frames, this means the data has been queued processed. For STREAM frames, this means the data has been queued
(but not necessarily delivered to the application). This also means (but not necessarily delivered to the application). This also means
skipping to change at page 55, line 38 skipping to change at page 62, line 46
o Store additional information from the IP or UDP headers from DF o Store additional information from the IP or UDP headers from DF
packets (for example, the IP ID or UDP checksum) to further packets (for example, the IP ID or UDP checksum) to further
authenticate incoming Datagram Too Big messages. authenticate incoming Datagram Too Big messages.
o Any reduction in PMTU due to a report contained in an ICMP packet o Any reduction in PMTU due to a report contained in an ICMP packet
is provisional until QUIC's loss detection algorithm determines is provisional until QUIC's loss detection algorithm determines
that the packet is actually lost. that the packet is actually lost.
10. Streams: QUIC's Data Structuring Abstraction 10. Streams: QUIC's Data Structuring Abstraction
Streams in QUIC provide a lightweight, ordered, and bidirectional Streams in QUIC provide a lightweight, ordered byte-stream
byte-stream abstraction modeled closely on HTTP/2 streams [RFC7540]. abstraction.
Streams can be created either by the client or the server, can There are two basic types of stream in QUIC. Unidirectional streams
carry data in one direction only; bidirectional streams allow for
data to be sent in both directions. Different stream identifiers are
used to distinguish between unidirectional and bidirectional streams,
as well as to create a separation between streams that are initiated
by the client and server (see Section 10.1).
Either type of stream can be created by either endpoint, can
concurrently send data interleaved with other streams, and can be concurrently send data interleaved with other streams, and can be
cancelled. cancelled.
Data that is received on a stream is delivered in order within that Data that is received on a stream is delivered in order within that
stream, but there is no particular delivery order across streams. stream, but there is no particular delivery order across streams.
Transmit ordering among streams is left to the implementation. Transmit ordering among streams is left to the implementation.
The creation and destruction of streams are expected to have minimal The creation and destruction of streams are expected to have minimal
bandwidth and computational cost. A single STREAM frame may create, bandwidth and computational cost. A single STREAM frame may create,
carry data for, and terminate a stream, or a stream may last the carry data for, and terminate a stream, or a stream may last the
skipping to change at page 56, line 17 skipping to change at page 63, line 33
streams is also flow controlled, with each peer declaring the maximum streams is also flow controlled, with each peer declaring the maximum
stream ID it is willing to accept at a given time. stream ID it is willing to accept at a given time.
An alternative view of QUIC streams is as an elastic "message" An alternative view of QUIC streams is as an elastic "message"
abstraction, similar to the way ephemeral streams are used in SST abstraction, similar to the way ephemeral streams are used in SST
[SST], which may be a more appealing description for some [SST], which may be a more appealing description for some
applications. applications.
10.1. Stream Identifiers 10.1. Stream Identifiers
Streams are identified by an unsigned 32-bit integer, referred to as Streams are identified by an unsigned 62-bit integer, referred to as
the Stream ID. To avoid Stream ID collision, clients MUST initiate the Stream ID. The least significant two bits of the Stream ID are
streams using odd-numbered Stream IDs; servers MUST initiate streams used to identify the type of stream (unidirectional or bidirectional)
using even-numbered Stream IDs. If an endpoint receives a frame and the initiator of the stream.
which corresponds to a stream which is allocated to it (i.e., odd-
numbered for the client or even-numbered for the server) but which it
has not yet created, it MUST close the connection with error code
STREAM_STATE_ERROR.
Stream ID 0 (0x0) is reserved for the cryptographic handshake. The least significant bit (0x1) of the Stream ID identifies the
Stream 0 MUST NOT be used for application data, and is the first initiator of the stream. Clients initiate even-numbered streams
client-initiated stream. (those with the least significant bit set to 0); servers initiate
odd-numbered streams (with the bit set to 1). Separation of the
stream identifiers ensures that client and server are able to open
streams without the latency imposed by negotiating for an identifier.
A QUIC endpoint MUST NOT reuse a Stream ID. Streams MUST be created If an endpoint receives a frame for a stream that it expects to
in sequential order. Open streams can be used in any order. Streams initiate (i.e., odd-numbered for the client or even-numbered for the
that are used out of order result in lower-numbered streams in the server), but which it has not yet opened, it MUST close the
same direction being counted as open. connection with error code STREAM_STATE_ERROR.
Stream IDs are usually encoded as a 32-bit integer, though the STREAM The second least significant bit (0x2) of the Stream ID
frame (Section 8.15) permits a shorter encoding when the leading bits differentiates between unidirectional streams and bidirectional
of the stream ID are zero. streams. Unidirectional streams always have this bit set to 1 and
bidirectional streams have this bit set to 0.
10.2. Life of a Stream The two type bits from a Stream ID therefore identify streams as
summarized in Table 5.
The semantics of QUIC streams is based on HTTP/2 streams, and the +----------+----------------------------------+
lifecycle of a QUIC stream therefore closely follows that of an | Low Bits | Stream Type |
HTTP/2 stream [RFC7540], with some differences to accommodate the +----------+----------------------------------+
possibility of out-of-order delivery due to the use of multiple | 0x0 | Client-Initiated, Bidirectional |
streams in QUIC. The lifecycle of a QUIC stream is shown in the | | |
following figure and described below. | 0x1 | Server-Initiated, Bidirectional |
| | |
| 0x2 | Client-Initiated, Unidirectional |
| | |
| 0x3 | Server-Initiated, Unidirectional |
+----------+----------------------------------+
+--------+ Table 5: Stream ID Types
| |
| idle |
| |
+--------+
|
send/recv STREAM/RST
recv MSD/SB
|
v
recv FIN/ +--------+ send FIN/
recv RST | | send RST
,---------| open |-----------.
/ | | \
v +--------+ v
+----------+ +----------+
| half | | half |
| closed | | closed |
| (remote) | | (local) |
+----------+ +----------+
| |
| send FIN/ +--------+ recv FIN/ |
\ send RST | | recv RST /
`----------->| closed |<-------------'
| |
+--------+
send: endpoint sends this frame Stream ID 0 (0x0) is a client-initiated, bidirectional stream that is
recv: endpoint receives this frame used for the cryptographic handshake. Stream 0 MUST NOT be used for
application data.
STREAM: a STREAM frame A QUIC endpoint MUST NOT reuse a Stream ID. Open streams can be used
FIN: FIN flag in a STREAM frame in any order. Streams that are used out of order result in opening
RST: RST_STREAM frame all lower-numbered streams of the same type in the same direction.
MSD: MAX_STREAM_DATA frame
SB: STREAM_BLOCKED frame
Figure 10: Lifecycle of a stream Stream IDs are encoded as a variable-length integer (see
Section 8.1).
Note that this diagram shows stream state transitions and the frames 10.2. Stream States
and flags that affect those transitions only. It is possible for a
single frame to cause two transitions: receiving a RST_STREAM frame,
or a STREAM frame with the FIN flag cause the stream state to move
from "idle" to "open" and then immediately to one of the "half-
closed" states.
The recipient of a frame that changes stream state will have a This section describes the two types of QUIC stream in terms of the
delayed view of the state of a stream while the frame is in transit. states of their send or receive components. Two state machines are
Endpoints do not coordinate the creation of streams; they are created described: one for streams on which an endpoint transmits data
unilaterally by either endpoint. Endpoints can use acknowledgments (Section 10.2.1); another for streams from which an endpoint receives
to understand the peer's subjective view of stream state at any given data (Section 10.2.2).
time.
In the absence of more specific guidance elsewhere in this document, Unidirectional streams use the applicable state machine directly.
implementations SHOULD treat the receipt of a frame that is not Bidirectional streams use both state machines. For the most part,
expressly permitted in the description of a state as a connection the use of these state machines is the same whether the stream is
error (see Section 12). unidirectional or bidirectional. The conditions for opening a stream
are slightly more complex for a bidirectional stream because the
opening of either send or receive causes the stream to open in both
directions.
10.2.1. idle Opening a stream causes all lower-numbered streams of the same type
to implicitly open. This includes both send and receive streams if
the stream is bidirectional. For bidirectional streams, an endpoint
can send data on an implicitly opened stream. On both unidirectional
and bidirectional streams, an endpoint MAY send MAX_STREAM_DATA or
STOP_SENDING on implicitly opened streams. An endpoint SHOULD NOT
implicitly open streams that it initiates, instead opening streams in
order.
All streams start in the "idle" state. Note: These states are largely informative. This document uses
stream states to describe rules for when and how different types
of frames can be sent and the reactions that are expected when
different types of frames are received. Though these state
machines are intended to be useful in implementing QUIC, these
states aren't intended to constrain implementations. An
implementation can define a different state machine as long as its
behavior is consistent with an implementation that implements
these states.
The following transitions are valid from this state: 10.2.1. Send Stream States
Sending or receiving a STREAM or RST_STREAM frame causes the Figure 10 shows the states for the part of a stream that sends data
identified stream to become "open". The stream identifier for a new to a peer.
stream is selected as described in Section 10.1. A RST_STREAM frame,
or a STREAM frame with the FIN flag set also causes a stream to
become "half-closed".
An endpoint might receive MAX_STREAM_DATA or STREAM_BLOCKED frames on o
peer-initiated streams that are "idle" if there is loss or reordering | Application Open
of packets. Receiving these frames also causes the stream to become | Open Paired Stream (bidirectional)
"open". v
+-------+
| Open | Send RST_STREAM
| |-----------------------.
+-------+ |
| |
| Send STREAM / |
| STREAM_BLOCKED |
v |
+-------+ |
| Send | Send RST_STREAM |
| |---------------------->|
+-------+ |
| |
| Send STREAM + FIN |
v v
+-------+ +-------+
| Data | Send RST_STREAM | Reset |
| Sent +------------------>| Sent |
+-------+ +-------+
| |
| Recv All ACKs | Recv ACK
v v
+-------+ +-------+
| Data | | Reset |
| Recvd | | Recvd |
+-------+ +-------+
An endpoint MUST NOT send a STREAM or RST_STREAM frame for a stream Figure 10: States for Send Streams
ID that is higher than the peers advertised maximum stream ID (see
Section 8.7).
10.2.2. open 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
application protocol. The "Open" state represents a newly created
stream that is able to accept data from the application. Stream data
might be buffered in this state in preparation for sending.
A stream in the "open" state may be used by both peers to send frames The sending part of a bidirectional stream initiated by a peer (type
of any type. In this state, endpoints can send MAX_STREAM_DATA and 0 for a server, type 1 for a client) enters the "Open" state if the
MUST observe the value advertised by its receiving peer (see receiving part enters the "Recv" state.
Section 11).
Opening a stream causes all lower-numbered streams in the same Sending the first STREAM or STREAM_BLOCKED frame causes a send stream
direction to become open. Thus, opening an odd-numbered stream to enter the "Send" state. An implementation might choose to defer
causes all "idle", odd-numbered streams with a lower identifier to allocating a Stream ID to a send stream until it sends the first
become open and the same applies to even numbered streams. Endpoints frame and enters this state, which can allow for better stream
open streams in increasing numeric order, but loss or reordering can prioritization.
cause packets that open streams to arrive out of order.
From the "open" state, either endpoint can send a frame with the FIN In the "Send" state, an endpoint transmits - and retransmits as
flag set, which causes the stream to transition into one of the necessary - data in STREAM frames. The endpoint respects the flow
"half-closed" states. This flag can be set on the frame that opens control limits of its peer, accepting MAX_STREAM_DATA frames. An
the stream, which causes the stream to immediately become "half- endpoint in the "Send" state generates STREAM_BLOCKED frames if it
closed". Once an endpoint has completed sending all stream data and encounters flow control limits.
a STREAM frame with a FIN flag, the stream state becomes "half-closed
(local)". When an endpoint receives all stream data and a FIN flag
the stream state becomes "half-closed (remote)". An endpoint MUST
NOT consider the stream state to have changed until all data has been
sent or received.
A RST_STREAM frame on an "open" stream also causes the stream to After the application indicates that stream data is complete and a
become "half-closed". A stream that becomes "open" as a result of STREAM frame containing the FIN bit is sent, the send stream enters
sending or receiving RST_STREAM immediately becomes "half-closed". the "Data Sent" state. From this state, the endpoint only
Sending a RST_STREAM frame causes the stream to become "half-closed retransmits stream data as necessary. The endpoint no longer needs
(local)"; receiving RST_STREAM causes the stream to become "half- to track flow control limits or send STREAM_BLOCKED frames for a send
closed (remote)". stream in this state. The endpoint can ignore any MAX_STREAM_DATA
frames it receives from its peer in this state; MAX_STREAM_DATA
frames might be received until the peer receives the final stream
offset.
Any frame type that mentions a stream ID can be sent in this state. Once all stream data has been successfully acknowledged, the send
stream enters the "Data Recvd" state, which is a terminal state.
10.2.3. half-closed (local) From any of the "Open", "Send", or "Data Sent" states, an application
can signal that it wishes to abandon transmission of stream data.
Similarly, the endpoint might receive a STOP_SENDING frame from its
peer. In either case, the endpoint sends a RST_STREAM frame, which
causes the stream to enter the "Reset Sent" state.
A stream that is in the "half-closed (local)" state MUST NOT be used An endpoint MAY send a RST_STREAM as the first frame on a send
for sending on new STREAM frames. Retransmission of data that has stream; this causes the send stream to open and then immediately
already been sent on STREAM frames is permitted. An endpoint MAY transition to the "Reset Sent" state.
also send MAX_STREAM_DATA and STOP_SENDING in this state.
An application can decide to abandon a stream in this state. An Once a packet containing a RST_STREAM has been acknowledged, the send
endpoint can send RST_STREAM for a stream that was closed with the stream enters the "Reset Recvd" state, which is a terminal state.
FIN flag. The final offset carried in this RST_STREAM frame MUST be
the same as the previously established final offset.
An endpoint that closes a stream MUST NOT send data beyond the final 10.2.2. Receive Stream States
offset that it has chosen, see Section 10.2.5 for details.
A stream transitions from this state to "closed" when a STREAM frame Figure 11 shows the states for the part of a stream that receives
that contains a FIN flag is received and all prior data has arrived, data from a peer. The states for a receive stream mirror only some
or when a RST_STREAM frame is received. 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
as the "Open" state; instead, receive streams track the delivery of
data to the application or application protocol some of which cannot
be observed by the sender.
An endpoint can receive any frame that mentions a stream ID in this o
state. Providing flow-control credit using MAX_STREAM_DATA frames is | Recv STREAM / STREAM_BLOCKED / RST_STREAM
necessary to continue receiving flow-controlled frames. In this | Open Paired Stream (bidirectional)
state, a receiver MAY ignore MAX_STREAM_DATA frames for this stream, | Recv MAX_STREAM_DATA
which might arrive for a short period after a frame bearing the FIN v
flag is sent. +-------+
| Recv | Recv RST_STREAM
| |-----------------------.
+-------+ |
| |
| Recv STREAM + FIN |
v |
+-------+ |
| Size | Recv RST_STREAM |
| Known +---------------------->|
+-------+ |
| |
| Recv All Data |
v v
+-------+ +-------+
| Data | Recv RST_STREAM | Reset |
| Recvd +<-- (optional) --->| Recvd |
+-------+ +-------+
| |
| App Read All Data | App Read RST
v v
+-------+ +-------+
| Data | | Reset |
| Read | | Read |
+-------+ +-------+
10.2.4. half-closed (remote) Figure 11: States for Receive Streams
A stream is "half-closed (remote)" when the stream is no longer being The receiving part of a stream initiated by a peer (types 1 and 3 for
used by the peer to send any data. An endpoint will have either a client, or 0 and 2 for a server) are created when the first STREAM,
received all data that a peer has sent or will have received a STREAM_BLOCKED, RST_STREAM, or MAX_STREAM_DATA (bidirectional only,
RST_STREAM frame and discarded any received data. 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 to immediately transition to the "Reset Recvd".
Once all data has been either received or discarded, a sender is no The receive stream enters the "Recv" state when the sending part of a
longer obligated to update the maximum received data for the bidirectional stream initiated by the endpoint (type 0 for a client,
connection. type 1 for a server) enters the "Open" state.
Due to reordering, an endpoint could continue receiving frames for A bidirectional stream also opens when a MAX_STREAM_DATA frame is
the stream even after the stream is closed for sending. Frames received. Receiving a MAX_STREAM_DATA frame implies that the remote
received after a peer closes a stream SHOULD be discarded. An peer has opened the stream and is providing flow control credit. A
endpoint MAY choose to limit the period over which it ignores frames MAX_STREAM_DATA frame might arrive before a STREAM or STREAM_BLOCKED
and treat frames that arrive after this time as being in error. frame if packets are lost or reordered.
An endpoint may receive a RST_STREAM in this state, such as when the In the "Recv" state, the endpoint receives STREAM and STREAM_BLOCKED
peer resets the stream after sending a FIN on it. In this case, the frames. Incoming data is buffered and reassembled into the correct
endpoint MAY discard any data that it already received on that order for delivery to the application. As data is consumed by the
stream. The endpoint SHOULD close the connection with a application and buffer space becomes available, the endpoint sends
FINAL_OFFSET_ERROR if the received RST_STREAM carries a different MAX_STREAM_DATA frames to allow the peer to send more data.
offset from the one already established.
An endpoint will know the final offset of the data it receives on a When a STREAM frame with a FIN bit is received, the final offset (see
stream when it reaches the "half-closed (remote)" state, see Section 11.3) is known. The receive stream enters the "Size Known"
Section 11.3 for details. state. In this state, the endpoint no longer needs to send
MAX_STREAM_DATA frames, it only receives any retransmissions of
stream data.
A stream in this state can be used by the endpoint to send any frame Once all data for the stream has been received, the receive stream
that mentions a stream ID. In this state, the endpoint MUST observe enters the "Data Recvd" state. This might happen as a result of
advertised stream and connection data limits (see Section 11). receiving the same STREAM frame that causes the transition to "Size
Known". In this state, the endpoint has all stream data. Any STREAM
or STREAM_BLOCKED frames it receives for the stream can be discarded.
A stream transitions from this state to "closed" by completing The "Data Recvd" state persists until stream data has been delivered
transmission of all data. This includes sending all data carried in to the application or application protocol. Once stream data has
STREAM frames including the terminal STREAM frame that contains a FIN been delivered, the stream enters the "Data Read" state, which is a
flag. terminal state.
A stream also becomes "closed" when the endpoint sends a RST_STREAM Receiving a RST_STREAM frame in the "Recv" or "Size Known" states
frame. causes the stream to enter the "Reset Recvd" state. This might cause
the delivery of stream data to the application to be interrupted.
10.2.5. closed It is possible that all stream data is received when a RST_STREAM is
received (that is, from the "Data Recvd" state). Similarly, it is
possible for remaining stream data to arrive after receiving a
RST_STREAM frame (the "Reset Recvd" state). An implementation is
able to manage this situation as they choose. Sending RST_STREAM
means that an endpoint cannot guarantee delivery of stream data;
however there is no requirement that stream data not be delivered if
a RST_STREAM is received. An implementation MAY interrupt delivery
of stream data, discard any data that was not consumed, and signal
the existence of the RST_STREAM immediately. Alternatively, the
RST_STREAM signal might be suppressed or withheld if stream data is
completely received. In the latter case, the receive stream
effectively transitions to "Data Recvd" from "Reset Recvd".
The "closed" state is the terminal state for a stream. Reordering Once the application has been delivered the signal indicating that
might cause frames to be received after closing, see Section 10.2.4. the receive stream was reset, the receive stream transitions to the
"Reset Read" state, which is a terminal state.
If the application resets a stream that is already in the "closed" 10.2.3. Permitted Frame Types
state, a RST_STREAM frame MAY still be sent in order to cancel
retransmissions of previously-sent STREAM frames. The sender of a stream sends just three frame types that affect the
state of a stream at either sender or receiver: STREAM
(Section 8.17), STREAM_BLOCKED (Section 8.11), and RST_STREAM
(Section 8.3).
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
STREAM_BLOCKED after sending a RST_STREAM; that is, in the "Reset
Sent" state in addition to the terminal states. A receiver could
receive any of these frames in any state, but only due to the
possibility of delayed delivery of packets carrying them.
The receiver of a stream sends MAX_STREAM_DATA (Section 8.7) and
STOP_SENDING frames (Section 8.14).
The receiver only sends MAX_STREAM_DATA in the "Recv" state. A
receiver can send STOP_SENDING in any state where it has not received
a RST_STREAM frame; that is states other than "Reset Recvd" or "Reset
Read". However there is little value in sending a STOP_SENDING frame
after all stream data has been received in the "Data Recvd" state. A
sender could receive these frames in any state as a result of delayed
delivery of packets.
10.2.4. Bidirectional Stream States
A bidirectional stream is composed of a send stream and a receive
stream. Implementations may represent states of the bidirectional
stream as composites of send and receive stream states. The simplest
model presents the stream as "open" when either send or receive
stream is in a non-terminal state and "closed" when both send and
receive streams are in a terminal state.
Table 6 shows a more complex mapping of bidirectional stream states
that loosely correspond to the stream states in HTTP/2 [HTTP2]. This
shows that multiple states on send or receive streams are mapped to
the same composite state. Note that this is just one possibility for
such a mapping; this mapping requires that data is acknowledged
before the transition to a "closed" or "half-closed" state.
+-----------------------+---------------------+---------------------+
| Send Stream | Receive Stream | Composite State |
+-----------------------+---------------------+---------------------+
| No Stream/Open | No Stream/Recv *1 | idle |
| | | |
| Open/Send/Data Sent | Recv/Size Known | open |
| | | |
| Open/Send/Data Sent | Data Recvd/Data | half-closed |
| | Read | (remote) |
| | | |
| Open/Send/Data Sent | Reset Recvd/Reset | half-closed |
| | Read | (remote) |
| | | |
| Data Recvd | Recv/Size Known | half-closed (local) |
| | | |
| Reset Sent/Reset | Recv/Size Known | half-closed (local) |
| Recvd | | |
| | | |
| Data Recvd | Recv/Size Known | half-closed (local) |
| | | |
| Reset Sent/Reset | Data Recvd/Data | closed |
| Recvd | Read | |
| | | |
| Reset Sent/Reset | Reset Recvd/Reset | closed |
| Recvd | Read | |
| | | |
| Data Recvd | Data Recvd/Data | closed |
| | Read | |
| | | |
| Data Recvd | Reset Recvd/Reset | closed |
| | Read | |
+-----------------------+---------------------+---------------------+
Table 6: Possible Mapping of Stream States to HTTP/2
Note (*1): A stream is considered "idle" if it has not yet been
created, or if the receive stream is in the "Recv" state without
yet having received any frames.
10.3. Solicited State Transitions 10.3. Solicited State Transitions
If an endpoint is no longer interested in the data it is receiving on If an endpoint is no longer interested in the data it is receiving on
a stream, it MAY send a STOP_SENDING frame identifying that stream to a stream, it MAY send a STOP_SENDING frame identifying that stream to
prompt closure of the stream in the opposite direction. This prompt closure of the stream in the opposite direction. This
typically indicates that the receiving application is no longer typically indicates that the receiving application is no longer
reading data it receives from the stream, but is not a guarantee that reading data it receives from the stream, but is not a guarantee that
incoming data will be ignored. incoming data will be ignored.
STREAM frames received after sending STOP_SENDING are still counted STREAM frames received after sending STOP_SENDING are still counted
toward the connection and stream flow-control windows, even though toward the connection and stream flow-control windows, even though
these frames will be discarded upon receipt. This avoids potential these frames will be discarded upon receipt. This avoids potential
ambiguity about which STREAM frames count toward flow control. ambiguity about which STREAM frames count toward flow control.
STOP_SENDING can only be sent for any stream that is not "idle", A STOP_SENDING frame requests that the receiving endpoint send a
however it is mostly useful for streams in the "open" or "half-closed RST_STREAM frame. An endpoint that receives a STOP_SENDING frame
(local)" states. A STOP_SENDING frame requests that the receiving MUST send a RST_STREAM frame for that stream, and can use an error
endpoint send a RST_STREAM frame. An endpoint that receives a code of STOPPING. If the STOP_SENDING frame is received on a send
STOP_SENDING frame MUST send a RST_STREAM frame for that stream with stream that is already in the "Data Sent" state, a RST_STREAM frame
an error code of STOPPING. If the STOP_SENDING frame is received on MAY still be sent in order to cancel retransmission of previously-
a stream that is already in the "half-closed (local)" or "closed" sent STREAM frames.
states, a RST_STREAM frame MAY still be sent in order to cancel
retransmission of previously-sent STREAM frames.
While STOP_SENDING frames are retransmittable, an implementation MAY STOP_SENDING SHOULD only be sent for a receive stream that has not
choose not to retransmit a lost STOP_SENDING frame if the stream has been reset. STOP_SENDING is most useful for streams in the "Recv" or
already been closed in the appropriate direction since the frame was "Size Known" states.
first generated. See Section 9.
An endpoint is expected to send another STOP_SENDING frame if a
packet containing a previous STOP_SENDING is lost. However, once
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
"Size Known" - sending a STOP_SENDING frame is unnecessary.
10.4. Stream Concurrency 10.4. Stream Concurrency
An endpoint limits the number of concurrently active incoming streams An endpoint limits the number of concurrently active incoming streams
by adjusting the maximum stream ID. An initial value is set in the by adjusting the maximum stream ID. An initial value is set in the
transport parameters (see Section 7.4.1) and is subsequently transport parameters (see Section 7.4.1) and is subsequently
increased by MAX_STREAM_ID frames (see Section 8.7). increased by MAX_STREAM_ID frames (see Section 8.8).
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
skipping to change at page 62, line 19 skipping to change at page 73, line 19
encapsulating data on a stream until the stream is terminated in that encapsulating data on a stream until the stream is terminated in that
direction. Streams are an ordered byte-stream abstraction, and they direction. Streams are an ordered byte-stream abstraction, and they
have no other structure within them. STREAM frame boundaries are not have no other structure within them. STREAM frame boundaries are not
expected to be preserved in retransmissions from the sender or during expected to be preserved in retransmissions from the sender or during
delivery to the application at the receiver. delivery to the application at the receiver.
When new data is to be sent on a stream, a sender MUST set the When new data is to be sent on a stream, a sender MUST set the
encapsulating STREAM frame's offset field to the stream offset of the encapsulating STREAM frame's offset field to the stream offset of the
first byte of this new data. The first byte of data that is sent on first byte of this new data. The first byte of data that is sent on
a stream has the stream offset 0. The largest offset delivered on a a stream has the stream offset 0. The largest offset delivered on a
stream MUST be less than 2^64. A receiver MUST ensure that received stream MUST be less than 2^62. A receiver MUST ensure that received
stream data is delivered to the application as an ordered byte- stream data is delivered to the application as an ordered byte-
stream. Data received out of order MUST be buffered for later stream. Data received out of order MUST be buffered for later
delivery, as long as it is not in violation of the receiver's flow delivery, as long as it is not in violation of the receiver's flow
control limits. control limits.
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. The cryptographic
handshake stream, Stream 0, is exempt from the connection-level data handshake stream, Stream 0, is exempt from the connection-level data
limits established by MAX_DATA. Data on stream 0 other than the limits established by MAX_DATA. Data on stream 0 other than the
initial cryptographic handshake message is still subject to stream- initial cryptographic handshake message is still subject to stream-
skipping to change at page 62, line 45 skipping to change at page 73, line 45
handshake message. handshake message.
Flow control is described in detail in Section 11, and congestion Flow control is described in detail in Section 11, and congestion
control is described in the companion document [QUIC-RECOVERY]. control is described in the companion document [QUIC-RECOVERY].
10.6. Stream Prioritization 10.6. 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 [RFC7540], shows that effective prioritization strategies have HTTP/2 [HTTP2], shows that effective prioritization strategies have a
a significant positive impact on performance. significant positive impact on performance.
QUIC does not provide frames for exchanging prioritization QUIC does not provide frames for exchanging prioritization
information. Instead it relies on receiving priority information information. Instead it relies on receiving priority information
from the application that uses QUIC. Protocols that use QUIC are from the application that uses QUIC. Protocols that use QUIC are
able to define any prioritization scheme that suits their application able to define any prioritization scheme that suits their application
semantics. A protocol might define explicit messages for signaling semantics. A protocol might define explicit messages for signaling
priority, such as those defined in HTTP/2; it could define rules that priority, such as those defined in HTTP/2; it could define rules that
allow an endpoint to determine priority based on context; or it could allow an endpoint to determine priority based on context; or it could
leave the determination to the application. leave the determination to the application.
skipping to change at page 63, line 44 skipping to change at page 74, line 44
11. Flow Control 11. Flow Control
It is necessary to limit the amount of data that a sender may have It is necessary to limit the amount of data that a sender may have
outstanding at any time, so as to prevent a fast sender from outstanding at any time, so as to prevent a fast sender from
overwhelming a slow receiver, or to prevent a malicious sender from overwhelming a slow receiver, or to prevent a malicious sender from
consuming significant resources at a receiver. This section consuming significant resources at a receiver. This section
describes QUIC's flow-control mechanisms. describes QUIC's flow-control mechanisms.
QUIC employs a credit-based flow-control scheme similar to HTTP/2's QUIC employs a credit-based flow-control scheme similar to HTTP/2's
flow control [RFC7540]. A receiver advertises the number of octets flow control [HTTP2]. A receiver advertises the number of octets it
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 the maximum absolute byte offset of a stream, while MAX_DATA
sends the maximum sum of the absolute byte offsets of all streams sends the maximum sum of the absolute byte offsets of all streams
skipping to change at page 64, line 23 skipping to change at page 75, line 23
advertisement; that is, once a receiver advertises an offset, it MUST advertisement; that is, once a receiver advertises an offset, it MUST
NOT subsequently advertise a smaller offset. A sender could receive NOT subsequently advertise a smaller offset. A sender could receive
MAX_DATA or MAX_STREAM_DATA frames out of order; a sender MUST MAX_DATA or MAX_STREAM_DATA frames out of order; a sender MUST
therefore ignore any flow control offset that does not move the therefore ignore any flow control offset that does not move the
window forward. window forward.
A receiver MUST close the connection with a FLOW_CONTROL_ERROR error A receiver MUST close the connection with a FLOW_CONTROL_ERROR error
(Section 12) if the peer violates the advertised connection or stream (Section 12) if the peer violates the advertised connection or stream
data limits. data limits.
A sender MUST send BLOCKED frames to indicate it has data to write A sender SHOULD send BLOCKED or STREAM_BLOCKED frames to indicate it
but is blocked by lack of connection or stream flow control credit. has data to write but is blocked by flow control limits. These
BLOCKED frames are expected to be sent infrequently in common cases, frames are expected to be sent infrequently in common cases, but they
but they are considered useful for debugging and monitoring purposes. are considered useful for debugging and monitoring purposes.
A receiver advertises credit for a stream by sending a A receiver advertises credit for a stream by sending a
MAX_STREAM_DATA frame with the Stream ID set appropriately. A MAX_STREAM_DATA frame with the Stream ID set appropriately. A
receiver could use the current offset of data consumed to determine receiver could use the current offset of data consumed to determine
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
skipping to change at page 66, line 24 skipping to change at page 77, line 24
Implementations will likely want to increase the maximum stream ID as Implementations will likely want to increase the maximum stream ID as
peer-initiated streams close. A receiver MAY also advance the peer-initiated streams close. A receiver MAY also advance the
maximum stream ID based on current activity, system conditions, and maximum stream ID based on current activity, system conditions, and
other environmental factors. other environmental factors.
11.2.1. Blocking on Flow Control 11.2.1. Blocking on Flow Control
If a sender does not receive a MAX_DATA or MAX_STREAM_DATA frame when If a sender does not receive a MAX_DATA or MAX_STREAM_DATA frame when
it has run out of flow control credit, the sender will be blocked and it has run out of flow control credit, the sender will be blocked and
MUST send a BLOCKED or STREAM_BLOCKED frame. These frames are SHOULD send a BLOCKED or STREAM_BLOCKED frame. These frames are
expected to be useful for debugging at the receiver; they do not expected to be useful for debugging at the receiver; they do not
require any other action. A receiver SHOULD NOT wait for a BLOCKED require any other action. A receiver SHOULD NOT wait for a BLOCKED
or STREAM_BLOCKED frame before sending MAX_DATA or MAX_STREAM_DATA, or STREAM_BLOCKED frame before sending MAX_DATA or MAX_STREAM_DATA,
since doing so will mean that a sender is unable to send for an since doing so will mean that a sender is unable to send for an
entire round trip. entire round trip.
For smooth operation of the congestion controller, it is generally For smooth operation of the congestion controller, it is generally
considered best to not let the sender go into quiescence if considered best to not let the sender go into quiescence if
avoidable. To avoid blocking a sender, and to reasonably account for avoidable. To avoid blocking a sender, and to reasonably account for
the possibiity of loss, a receiver should send a MAX_DATA or the possibiity of loss, a receiver should send a MAX_DATA or
MAX_STREAM_DATA frame at least two roundtrips before it expects the MAX_STREAM_DATA frame at least two roundtrips before it expects the
sender to get blocked. sender to get blocked.
A sender sends a single BLOCKED or STREAM_BLOCKED frame only once A sender sends a single BLOCKED or STREAM_BLOCKED frame only once
when it reaches a data limit. A sender MUST NOT send multiple when it reaches a data limit. A sender SHOULD NOT send multiple
BLOCKED or STREAM_BLOCKED frames for the same data limit, unless the BLOCKED or STREAM_BLOCKED frames for the same data limit, unless the
original frame is determined to be lost. Another BLOCKED or original frame is determined to be lost. Another BLOCKED or
STREAM_BLOCKED frame can be sent after the data limit is increased. STREAM_BLOCKED frame can be sent after the data limit is increased.
11.3. Stream Final Offset 11.3. Stream Final Offset
The final offset is the count of the number of octets that are The final offset is the count of the number of octets that are
transmitted on a stream. For a stream that is reset, the final transmitted on a stream. For a stream that is reset, the final
offset is carried explicitly in the RST_STREAM frame. Otherwise, the offset is carried explicitly in a RST_STREAM frame. Otherwise, the
final offset is the offset of the end of the data carried in STREAM final offset is the offset of the end of the data carried in a STREAM
frame marked with a FIN flag. frame marked with a FIN flag, or 0 in the case of incoming
unidirectional streams.
An endpoint will know the final offset for a stream when the stream An endpoint will know the final offset for a stream when the receive
enters the "half-closed (remote)" state. However, if there is stream enters the "Size Known" or "Reset Recvd" state.
reordering or loss, an endpoint might learn the final offset prior to
entering this state if it is carried on a STREAM frame.
An endpoint MUST NOT send data on a stream at or beyond the final An endpoint MUST NOT send data on a stream at or beyond the final
offset. offset.
Once a final offset for a stream is known, it cannot change. If a Once a final offset for a stream is known, it cannot change. If a
RST_STREAM or STREAM frame causes the final offset to change for a RST_STREAM or STREAM frame causes the final offset to change for a
stream, an endpoint SHOULD respond with a FINAL_OFFSET_ERROR error stream, an endpoint SHOULD respond with a FINAL_OFFSET_ERROR error
(see Section 12). A receiver SHOULD treat receipt of data at or (see Section 12). 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
skipping to change at page 67, line 34 skipping to change at page 78, line 32
An endpoint that detects an error SHOULD signal the existence of that An endpoint that detects an error SHOULD signal the existence of that
error to its peer. Errors can affect an entire connection (see error to its peer. Errors can affect an entire connection (see
Section 12.1), or a single stream (see Section 12.2). Section 12.1), or a single stream (see Section 12.2).
The most appropriate error code (Section 12.3) SHOULD be included in The most appropriate error code (Section 12.3) SHOULD be included in
the frame that signals the error. Where this specification the frame that signals the error. Where this specification
identifies error conditions, it also identifies the error code that identifies error conditions, it also identifies the error code that
is used. is used.
A stateless reset (Section 7.8.4) is not suitable for any error that A stateless reset (Section 7.9.4) is not suitable for any error that
can be signaled with a CONNECTION_CLOSE, APPLICATION_CLOSE, or can be signaled with a CONNECTION_CLOSE, APPLICATION_CLOSE, or
RST_STREAM frame. A stateless reset MUST NOT be used by an endpoint RST_STREAM frame. A stateless reset MUST NOT be used by an endpoint
that has the state necessary to send a frame on the connection. that has the state necessary to send a frame on the connection.
12.1. Connection Errors 12.1. Connection Errors
Errors that result in the connection being unusable, such as an Errors that result in the connection being unusable, such as an
obvious violation of protocol semantics or corruption of state that obvious violation of protocol semantics or corruption of state that
affects an entire connection, MUST be signaled using a affects an entire connection, MUST be signaled using a
CONNECTION_CLOSE or APPLICATION_CLOSE frame (Section 8.3, CONNECTION_CLOSE or APPLICATION_CLOSE frame (Section 8.4,
Section 8.4). An endpoint MAY close the connection in this manner Section 8.5). An endpoint MAY close the connection in this manner
even if the error only affects a single stream. even if the error only affects a single stream.
Application protocols can signal application-specific protocol errors Application protocols can signal application-specific protocol errors
using the APPLICATION_CLOSE frame. Errors that are specific to the using the APPLICATION_CLOSE frame. Errors that are specific to the
transport, including all those described in this document, are transport, including all those described in this document, are
carried in a CONNECTION_CLOSE frame. Other than the type of error carried in a CONNECTION_CLOSE frame. Other than the type of error
code they carry, these frames are identical in format and semantics. code they carry, these frames are identical in format and semantics.
A CONNECTION_CLOSE or APPLICATION_CLOSE frame could be sent in a A CONNECTION_CLOSE or APPLICATION_CLOSE frame could be sent in a
packet that is lost. An endpoint SHOULD be prepared to retransmit a packet that is lost. An endpoint SHOULD be prepared to retransmit a
packet containing either frame type if it receives more packets on a packet containing either frame type if it receives more packets on a
terminated connection. Limiting the number of retransmissions and terminated connection. Limiting the number of retransmissions and
the time over which this final packet is sent limits the effort the time over which this final packet is sent limits the effort
expended on terminated connections. expended on terminated connections.
An endpoint that chooses not to retransmit packets containing An endpoint that chooses not to retransmit packets containing
CONNECTION_CLOSE or APPLICATION_CLOSE risks a peer missing the first CONNECTION_CLOSE or APPLICATION_CLOSE risks a peer missing the first
such packet. The only mechanism available to an endpoint that such packet. The only mechanism available to an endpoint that
continues to receive data for a terminated connection is to use the continues to receive data for a terminated connection is to use the
stateless reset process (Section 7.8.4). stateless reset process (Section 7.9.4).
An endpoint that receives an invalid CONNECTION_CLOSE or An endpoint that receives an invalid CONNECTION_CLOSE or
APPLICATION_CLOSE frame MUST NOT signal the existence of the error to APPLICATION_CLOSE frame MUST NOT signal the existence of the error to
its peer. its peer.
12.2. Stream Errors 12.2. Stream Errors
If the error affects a single stream, but otherwise leaves the If the error affects a single stream, but otherwise leaves the
connection in a recoverable state, the endpoint can send a RST_STREAM connection in a recoverable state, the endpoint can send a RST_STREAM
frame (Section 8.2) with an appropriate error code to terminate just frame (Section 8.3) with an appropriate error code to terminate just
the affected stream. the affected stream.
Stream 0 is critical to the functioning of the entire connection. If Stream 0 is critical to the functioning of the entire connection. If
stream 0 is closed with either a RST_STREAM or STREAM frame bearing stream 0 is closed with either a RST_STREAM or STREAM frame bearing
the FIN flag, an endpoint MUST generate a connection error of type the FIN flag, an endpoint MUST generate a connection error of type
PROTOCOL_VIOLATION. PROTOCOL_VIOLATION.
RST_STREAM MUST be instigated by the application and MUST carry an RST_STREAM MUST be instigated by the application and MUST carry an
application error code. Resetting a stream without knowledge of the application error code. Resetting a stream without knowledge of the
application protocol could cause the protocol to enter an application protocol could cause the protocol to enter an
skipping to change at page 69, line 47 skipping to change at page 80, line 47
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_PONG (0xB): An endpoint received a PONG frame that did
not correspond to any PING frame that it previously sent.
FRAME_ERROR (0x1XX): An endpoint detected an error in a specific FRAME_ERROR (0x1XX): An endpoint detected an error in a specific
frame type. The frame type is included as the last octet of the frame type. The frame type is included as the last octet of the
error code. For example, an error in a MAX_STREAM_ID frame would error code. For example, an error in a MAX_STREAM_ID frame would
be indicated with the code (0x106). be indicated with the code (0x106).
See Section 14.2 for details of registering new error codes. See Section 14.2 for details of registering new error codes.
12.4. Application Protocol Error Codes 12.4. Application Protocol Error Codes
Application protocol error codes are 16-bit unsigned integers, but Application protocol error codes are 16-bit unsigned integers, but
the management of application error codes are left to application the management of application error codes are left to application
protocols. Application protocol error codes are used for the protocols. Application protocol error codes are used for the
RST_STREAM (Section 8.2) and APPLICATION_CLOSE (Section 8.4) frames. RST_STREAM (Section 8.3) and APPLICATION_CLOSE (Section 8.5) frames.
There is no restriction on the use of the 16-bit error code space for There is no restriction on the use of the 16-bit error code space for
application protocols. However, QUIC reserves the error code with a application protocols. However, QUIC reserves the error code with a
value of 0 to mean STOPPING. The application error code of STOPPING value of 0 to mean STOPPING. The application error code of STOPPING
(0) is used by the transport to cancel a stream in response to (0) is used by the transport to cancel a stream in response to
receipt of a STOP_SENDING frame. receipt of a STOP_SENDING frame.
13. Security and Privacy Considerations 13. Security and Privacy Considerations
13.1. Spoofed ACK Attack 13.1. Spoofed ACK Attack
skipping to change at page 72, line 41 skipping to change at page 83, line 45
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. The expert(s) are encouraged to be biased
towards approving registrations unless they are abusive, frivolous, towards approving registrations unless they are abusive, frivolous,
or actively harmful (not merely aesthetically displeasing, or or actively harmful (not merely aesthetically displeasing, or
architecturally dubious). architecturally dubious).
The initial contents of this registry are shown in Table 4. The initial contents of this registry are shown in Table 7.
+--------+-------------------------+---------------+ +--------+----------------------------+---------------+
| Value | Parameter Name | Specification | | Value | Parameter Name | Specification |
+--------+-------------------------+---------------+ +--------+----------------------------+---------------+
| 0x0000 | initial_max_stream_data | Section 7.4.1 | | 0x0000 | initial_max_stream_data | Section 7.4.1 |
| | | | | | | |
| 0x0001 | initial_max_data | Section 7.4.1 | | 0x0001 | initial_max_data | Section 7.4.1 |
| | | | | | | |
| 0x0002 | initial_max_stream_id | Section 7.4.1 | | 0x0002 | initial_max_stream_id_bidi | Section 7.4.1 |
| | | | | | | |
| 0x0003 | idle_timeout | Section 7.4.1 | | 0x0003 | idle_timeout | Section 7.4.1 |
| | | | | | | |
| 0x0004 | omit_connection_id | Section 7.4.1 | | 0x0004 | omit_connection_id | Section 7.4.1 |
| | | | | | | |
| 0x0005 | max_packet_size | Section 7.4.1 | | 0x0005 | max_packet_size | Section 7.4.1 |
| | | | | | | |
| 0x0006 | stateless_reset_token | Section 7.4.1 | | 0x0006 | stateless_reset_token | Section 7.4.1 |
+--------+-------------------------+---------------+ | | | |
| 0x0007 | ack_delay_exponent | Section 7.4.1 |
| | | |
| 0x0008 | initial_max_stream_id_uni | Section 7.4.1 |
+--------+----------------------------+---------------+
Table 4: Initial QUIC Transport Parameters Entries Table 7: Initial QUIC Transport Parameters Entries
14.2. QUIC Transport Error Codes Registry 14.2. QUIC Transport Error Codes Registry
IANA [SHALL add/has added] a registry for "QUIC Transport Error IANA [SHALL add/has added] a registry for "QUIC Transport Error
Codes" under a "QUIC Protocol" heading. Codes" under a "QUIC Protocol" heading.
The "QUIC Transport Error Codes" registry governs a 16-bit space. The "QUIC Transport Error Codes" registry governs a 16-bit space.
This space is split into two spaces that are governed by different This space is split into two spaces that are governed by different
policies. Values with the first byte in the range 0x00 to 0xfe (in policies. Values with the first byte in the range 0x00 to 0xfe (in
hexadecimal) are assigned via the Specification Required policy hexadecimal) are assigned via the Specification Required policy
skipping to change at page 73, line 50 skipping to change at page 85, line 5
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 5. Note The initial contents of this registry are shown in Table 8. Note
that FRAME_ERROR takes the range from 0x100 to 0x1FF and private use that FRAME_ERROR takes the range from 0x100 to 0x1FF and private use
occupies the range from 0xFE00 to 0xFFFF. occupies the range from 0xFE00 to 0xFFFF.
+-----------+------------------------+---------------+--------------+ +-----------+------------------------+---------------+--------------+
| Value | Error | Description | Specificatio | | Value | Error | Description | Specificatio |
| | | | n | | | | | n |
+-----------+------------------------+---------------+--------------+ +-----------+------------------------+---------------+--------------+
| 0x0 | NO_ERROR | No error | Section 12.3 | | 0x0 | NO_ERROR | No error | Section 12.3 |
| | | | | | | | | |
| 0x1 | INTERNAL_ERROR | Implementatio | Section 12.3 | | 0x1 | INTERNAL_ERROR | Implementatio | Section 12.3 |
skipping to change at page 74, line 44 skipping to change at page 86, line 44
| | | parameters | | | | | parameters | |
| | | | | | | | | |
| 0x9 | VERSION_NEGOTIATION_ER | Version | Section 12.3 | | 0x9 | VERSION_NEGOTIATION_ER | Version | Section 12.3 |
| | ROR | negotiation | | | | ROR | negotiation | |
| | | failure | | | | | failure | |
| | | | | | | | | |
| 0xA | PROTOCOL_VIOLATION | Generic | Section 12.3 | | 0xA | PROTOCOL_VIOLATION | Generic | Section 12.3 |
| | | protocol | | | | | protocol | |
| | | violation | | | | | violation | |
| | | | | | | | | |
| 0xB | UNSOLICITED_PONG | Unsolicited | Section 12.3 |
| | | PONG frame | |
| | | | |
| 0x100-0x1 | FRAME_ERROR | Specific | Section 12.3 | | 0x100-0x1 | FRAME_ERROR | Specific | Section 12.3 |
| FF | | frame format | | | FF | | frame format | |
| | | error | | | | | error | |
+-----------+------------------------+---------------+--------------+ +-----------+------------------------+---------------+--------------+
Table 5: Initial QUIC Transport Error Codes Entries Table 8: Initial QUIC Transport Error Codes Entries
15. References 15. References
15.1. Normative References 15.1. 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-tls13-22 (work in progress),
July 2017. November 2017.
[PLPMTUD] Mathis, M. and J. Heffner, "Packetization Layer Path MTU [PLPMTUD] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007,
<https://www.rfc-editor.org/info/rfc4821>. <https://www.rfc-editor.org/info/rfc4821>.
[PMTUDv4] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, [PMTUDv4] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990, DOI 10.17487/RFC1191, November 1990,
<https://www.rfc-editor.org/info/rfc1191>. <https://www.rfc-editor.org/info/rfc1191>.
[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-07 (work and Congestion Control", draft-ietf-quic-recovery-00 (work
in progress), October 2017. in progress), December 2017.
[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-07 (work in progress), October 2017. tls-00 (work in progress), December 2017.
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990, DOI 10.17487/RFC1191, November 1990,
<https://www.rfc-editor.org/info/rfc1191>. <https://www.rfc-editor.org/info/rfc1191>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
skipping to change at page 76, line 15 skipping to change at page 88, line 15
[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
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
15.2. Informative References 15.2. 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
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104, Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997, DOI 10.17487/RFC2104, February 1997,
<https://www.rfc-editor.org/info/rfc2104>. <https://www.rfc-editor.org/info/rfc2104>.
[RFC2360] Scott, G., "Guide for Internet Standards Writers", BCP 22, [RFC2360] Scott, G., "Guide for Internet Standards Writers", BCP 22,
RFC 2360, DOI 10.17487/RFC2360, June 1998, RFC 2360, DOI 10.17487/RFC2360, June 1998,
<https://www.rfc-editor.org/info/rfc2360>. <https://www.rfc-editor.org/info/rfc2360>.
[RFC4787] Audet, F., Ed. and C. Jennings, "Network Address [RFC4787] Audet, F., Ed. and C. Jennings, "Network Address
skipping to change at page 77, line 5 skipping to change at page 89, line 10
[RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure, [RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
"TCP Extensions for Multipath Operation with Multiple "TCP Extensions for Multipath Operation with Multiple
Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013, Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,
<https://www.rfc-editor.org/info/rfc6824>. <https://www.rfc-editor.org/info/rfc6824>.
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol "Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301, Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, <https://www.rfc-editor.org/info/rfc7301>. July 2014, <https://www.rfc-editor.org/info/rfc7301>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>.
[SLOWLORIS] [SLOWLORIS]
RSnake Hansen, R., "Welcome to Slowloris...", June 2009, RSnake Hansen, R., "Welcome to Slowloris...", June 2009,
<https://web.archive.org/web/20150315054838/ <https://web.archive.org/web/20150315054838/
http://ha.ckers.org/slowloris/>. http://ha.ckers.org/slowloris/>.
[SST] Ford, B., "Structured streams", ACM SIGCOMM Computer [SST] Ford, B., "Structured streams", ACM SIGCOMM Computer
Communication Review Vol. 37, pp. 361, Communication Review Vol. 37, pp. 361,
DOI 10.1145/1282427.1282421, October 2007. DOI 10.1145/1282427.1282421, October 2007.
15.3. URIs 15.3. URIs
[1] https://mailarchive.ietf.org/arch/search/?email_list=quic [1] https://mailarchive.ietf.org/arch/search/?email_list=quic
[2] https://github.com/quicwg [2] https://github.com/quicwg
[3] https://github.com/quicwg/base-drafts/labels/transport [3] https://github.com/quicwg/base-drafts/labels/-transport
[4] https://github.com/quicwg/base-drafts/wiki/QUIC-Versions [4] https://github.com/quicwg/base-drafts/wiki/QUIC-Versions
Appendix A. Contributors Appendix A. Contributors
The original authors of this specification were Ryan Hamilton, Jana The original authors of this specification were Ryan Hamilton, Jana
Iyengar, Ian Swett, and Alyssa Wilk. Iyengar, Ian Swett, and Alyssa Wilk.
The original design and rationale behind this protocol draw The original design and rationale behind this protocol draw
significantly from work by Jim Roskind [EARLY-DESIGN]. In significantly from work by Jim Roskind [EARLY-DESIGN]. In
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discussions and public ones on the quic@ietf.org and proto- discussions and public ones on the quic@ietf.org and proto-
quic@chromium.org mailing lists. Our thanks to all. quic@chromium.org mailing lists. Our thanks to all.
Appendix C. Change Log Appendix C. Change Log
*RFC Editor's Note:* Please remove this section prior to *RFC Editor's Note:* Please remove this section prior to
publication of a final version of this document. publication of a final version of this document.
Issue and pull request numbers are listed with a leading octothorp. Issue and pull request numbers are listed with a leading octothorp.
C.1. Since draft-ietf-quic-transport-06 C.1. Since draft-ietf-quic-transport-07
o Replaced FNV-1a with AES-GCM for all "Cleartext" packets. o Employ variable-length integer encodings throughout (#595)
C.2. Since draft-ietf-quic-transport-05 o Draining period can terminate early (#869)
C.2. Since draft-ietf-quic-transport-06
o Replaced FNV-1a with AES-GCM for all "Cleartext" packets (#554)
o Split error code space between application and transport (#485)
o Stateless reset token moved to end (#820)
o 1-RTT-protected long header types removed (#848)
o No acknowledgments during draining period (#852)
o Remove "application close" as a separate close type (#854)
o Remove timestamps from the ACK frame (#841)
o Require transport parameters to only appear once (#792)
C.3. 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.3. Since draft-ietf-quic-transport-04 C.4. Since draft-ietf-quic-transport-04
o Introduce STOP_SENDING frame, RST_STREAM only resets in one o Introduce STOP_SENDING frame, RST_STREAM only resets in one
direction (#165) direction (#165)
o Removed GOAWAY; application protocols are responsible for graceful o Removed GOAWAY; application protocols are responsible for graceful
shutdown (#696) shutdown (#696)
o Reduced the number of error codes (#96, #177, #184, #211) o Reduced the number of error codes (#96, #177, #184, #211)
o Version validation fields can't move or change (#121) o Version validation fields can't move or change (#121)
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o Increased the maximum length of the Largest Acknowledged field in o Increased the maximum length of the Largest Acknowledged field in
ACK frames to 64 bits (#629) ACK frames to 64 bits (#629)
o truncate_connection_id is renamed to omit_connection_id (#659) o truncate_connection_id is renamed to omit_connection_id (#659)
o CONNECTION_CLOSE terminates the connection like TCP RST (#330, o CONNECTION_CLOSE terminates the connection like TCP RST (#330,
#328) #328)
o Update labels used in HKDF-Expand-Label to match TLS 1.3 (#642) o Update labels used in HKDF-Expand-Label to match TLS 1.3 (#642)
C.4. Since draft-ietf-quic-transport-03 C.5. 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.5. Since draft-ietf-quic-transport-02 C.6. Since draft-ietf-quic-transport-02
o The size of the initial packet payload has a fixed minimum (#267, o The size of the initial packet payload has a fixed minimum (#267,
#472) #472)
o Define when Version Negotiation packets are ignored (#284, #294, o Define when Version Negotiation packets are ignored (#284, #294,
#241, #143, #474) #241, #143, #474)
o The 64-bit FNV-1a algorithm is used for integrity protection of o The 64-bit FNV-1a algorithm is used for integrity protection of
unprotected packets (#167, #480, #481, #517) unprotected packets (#167, #480, #481, #517)
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linkability (#232, #491, #496) linkability (#232, #491, #496)
o Transport parameters for 0-RTT are retained from a previous o Transport parameters for 0-RTT are retained from a previous
connection (#405, #513, #512) connection (#405, #513, #512)
* A client in 0-RTT no longer required to reset excess streams * A client in 0-RTT no longer required to reset excess streams
(#425, #479) (#425, #479)
o Expanded security considerations (#440, #444, #445, #448) o Expanded security considerations (#440, #444, #445, #448)
C.6. Since draft-ietf-quic-transport-01 C.7. 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)
o Narrow the packet number encoding range requirement (#67, #286, o Narrow the packet number encoding range requirement (#67, #286,
#299, #323, #356) #299, #323, #356)
o Defined client address validation (#52, #118, #120, #275) o Defined client address validation (#52, #118, #120, #275)
o Define transport parameters as a TLS extension (#49, #122) o Define transport parameters as a TLS extension (#49, #122)
o SCUP and COPT parameters are no longer valid (#116, #117) o SCUP and COPT parameters are no longer valid (#116, #117)
o Transport parameters for 0-RTT are either remembered from before, o Transport parameters for 0-RTT are either remembered from before,
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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.7. Since draft-ietf-quic-transport-00 C.8. 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.8. Since draft-hamilton-quic-transport-protocol-01 C.9. Since draft-hamilton-quic-transport-protocol-01
o Adopted as base for draft-ietf-quic-tls o Adopted as base for draft-ietf-quic-tls
o Updated authors/editors list o Updated authors/editors list
o Added IANA Considerations section o Added IANA Considerations section
o Moved Contributors and Acknowledgments to appendices o Moved Contributors and Acknowledgments to appendices
Authors' Addresses Authors' Addresses
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