draft-ietf-quic-transport-14.txt   draft-ietf-quic-transport-15.txt 
QUIC J. Iyengar, Ed. QUIC J. Iyengar, Ed.
Internet-Draft Fastly Internet-Draft Fastly
Intended status: Standards Track M. Thomson, Ed. Intended status: Standards Track M. Thomson, Ed.
Expires: February 16, 2019 Mozilla Expires: April 6, 2019 Mozilla
August 15, 2018 October 03, 2018
QUIC: A UDP-Based Multiplexed and Secure Transport QUIC: A UDP-Based Multiplexed and Secure Transport
draft-ietf-quic-transport-14 draft-ietf-quic-transport-15
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>. <https://mailarchive.ietf.org/arch/search/?email_list=quic>.
Working Group information can be found at <https://github.com/ Working Group information can be found at <https://github.com/
quicwg>; source code and issues list for this draft can be found at quicwg>; source code and issues list for this draft can be found at
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This Internet-Draft will expire on February 16, 2019. This Internet-Draft will expire on April 6, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 6 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 6
2.1. Notational Conventions . . . . . . . . . . . . . . . . . 7 2.1. Notational Conventions . . . . . . . . . . . . . . . . . 7
3. Versions . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Versions . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Packet Types and Formats . . . . . . . . . . . . . . . . . . 8 4. Packet Types and Formats . . . . . . . . . . . . . . . . . . 8
4.1. Long Header . . . . . . . . . . . . . . . . . . . . . . . 8 4.1. Long Header . . . . . . . . . . . . . . . . . . . . . . . 8
4.2. Short Header . . . . . . . . . . . . . . . . . . . . . . 11 4.2. Short Header . . . . . . . . . . . . . . . . . . . . . . 11
4.3. Version Negotiation Packet . . . . . . . . . . . . . . . 12 4.3. Version Negotiation Packet . . . . . . . . . . . . . . . 12
4.4. Retry Packet . . . . . . . . . . . . . . . . . . . . . . 14 4.4. Retry Packet . . . . . . . . . . . . . . . . . . . . . . 14
4.5. Cryptographic Handshake Packets . . . . . . . . . . . . . 16 4.5. Cryptographic Handshake Packets . . . . . . . . . . . . . 16
4.6. Initial Packet . . . . . . . . . . . . . . . . . . . . . 16 4.6. Initial Packet . . . . . . . . . . . . . . . . . . . . . 17
4.6.1. Connection IDs . . . . . . . . . . . . . . . . . . . 18 4.6.1. Connection IDs . . . . . . . . . . . . . . . . . . . 18
4.6.2. Tokens . . . . . . . . . . . . . . . . . . . . . . . 19 4.6.2. Tokens . . . . . . . . . . . . . . . . . . . . . . . 19
4.6.3. Starting Packet Numbers . . . . . . . . . . . . . . . 20 4.6.3. Starting Packet Numbers . . . . . . . . . . . . . . . 20
4.6.4. 0-RTT Packet Numbers . . . . . . . . . . . . . . . . 20 4.6.4. 0-RTT Packet Numbers . . . . . . . . . . . . . . . . 20
4.6.5. Minimum Packet Size . . . . . . . . . . . . . . . . . 20 4.6.5. Minimum Packet Size . . . . . . . . . . . . . . . . . 21
4.7. Handshake Packet . . . . . . . . . . . . . . . . . . . . 21 4.7. Handshake Packet . . . . . . . . . . . . . . . . . . . . 21
4.8. Protected Packets . . . . . . . . . . . . . . . . . . . . 21 4.8. Protected Packets . . . . . . . . . . . . . . . . . . . . 22
4.9. Coalescing Packets . . . . . . . . . . . . . . . . . . . 22 4.9. Coalescing Packets . . . . . . . . . . . . . . . . . . . 22
4.10. Connection ID Encoding . . . . . . . . . . . . . . . . . 23 4.10. Connection ID Encoding . . . . . . . . . . . . . . . . . 23
4.11. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 24 4.11. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 24
5. Frames and Frame Types . . . . . . . . . . . . . . . . . . . 26 5. Frames and Frame Types . . . . . . . . . . . . . . . . . . . 27
5.1. Extension Frames . . . . . . . . . . . . . . . . . . . . 29 5.1. Extension Frames . . . . . . . . . . . . . . . . . . . . 30
6. Life of a Connection . . . . . . . . . . . . . . . . . . . . 29 6. Life of a Connection . . . . . . . . . . . . . . . . . . . . 30
6.1. Connection ID . . . . . . . . . . . . . . . . . . . . . . 30 6.1. Connection ID . . . . . . . . . . . . . . . . . . . . . . 31
6.2. Matching Packets to Connections . . . . . . . . . . . . . 31 6.1.1. Issuing Connection IDs . . . . . . . . . . . . . . . 31
6.2.1. Client Packet Handling . . . . . . . . . . . . . . . 31 6.1.2. Consuming and Retiring Connection IDs . . . . . . . . 32
6.2.2. Server Packet Handling . . . . . . . . . . . . . . . 32 6.2. Matching Packets to Connections . . . . . . . . . . . . . 32
6.3. Version Negotiation . . . . . . . . . . . . . . . . . . . 32 6.2.1. Client Packet Handling . . . . . . . . . . . . . . . 33
6.3.1. Sending Version Negotiation Packets . . . . . . . . . 33 6.2.2. Server Packet Handling . . . . . . . . . . . . . . . 33
6.3.2. Handling Version Negotiation Packets . . . . . . . . 33 6.3. Version Negotiation . . . . . . . . . . . . . . . . . . . 34
6.3.3. Using Reserved Versions . . . . . . . . . . . . . . . 34 6.3.1. Sending Version Negotiation Packets . . . . . . . . . 34
6.4. Cryptographic and Transport Handshake . . . . . . . . . . 34 6.3.2. Handling Version Negotiation Packets . . . . . . . . 35
6.5. Example Handshake Flows . . . . . . . . . . . . . . . . . 35 6.3.3. Using Reserved Versions . . . . . . . . . . . . . . . 35
6.6. Transport Parameters . . . . . . . . . . . . . . . . . . 37 6.4. Cryptographic and Transport Handshake . . . . . . . . . . 36
6.6.1. Transport Parameter Definitions . . . . . . . . . . . 39 6.5. Example Handshake Flows . . . . . . . . . . . . . . . . . 37
6.6.2. Values of Transport Parameters for 0-RTT . . . . . . 41 6.6. Transport Parameters . . . . . . . . . . . . . . . . . . 38
6.6.3. New Transport Parameters . . . . . . . . . . . . . . 42 6.6.1. Transport Parameter Definitions . . . . . . . . . . . 41
6.6.4. Version Negotiation Validation . . . . . . . . . . . 42 6.6.2. Values of Transport Parameters for 0-RTT . . . . . . 43
6.7. Stateless Retries . . . . . . . . . . . . . . . . . . . . 44 6.6.3. New Transport Parameters . . . . . . . . . . . . . . 44
6.8. Using Explicit Congestion Notification . . . . . . . . . 44 6.6.4. Version Negotiation Validation . . . . . . . . . . . 45
6.9. Proof of Source Address Ownership . . . . . . . . . . . . 46 6.7. Stateless Retries . . . . . . . . . . . . . . . . . . . . 46
6.9.1. Client Address Validation Procedure . . . . . . . . . 47 6.8. Using Explicit Congestion Notification . . . . . . . . . 46
6.9.2. Address Validation for Future Connections . . . . . . 47 6.9. Proof of Source Address Ownership . . . . . . . . . . . . 48
6.9.3. Address Validation Token Integrity . . . . . . . . . 48 6.9.1. Client Address Validation Procedure . . . . . . . . . 49
6.10. Path Validation . . . . . . . . . . . . . . . . . . . . . 48 6.9.2. Address Validation for Future Connections . . . . . . 50
6.10.1. Initiation . . . . . . . . . . . . . . . . . . . . . 49 6.9.3. Address Validation Token Integrity . . . . . . . . . 50
6.10.2. Response . . . . . . . . . . . . . . . . . . . . . . 49 6.10. Path Validation . . . . . . . . . . . . . . . . . . . . . 51
6.10.3. Completion . . . . . . . . . . . . . . . . . . . . . 50 6.10.1. Initiation . . . . . . . . . . . . . . . . . . . . . 51
6.10.4. Abandonment . . . . . . . . . . . . . . . . . . . . 50 6.10.2. Response . . . . . . . . . . . . . . . . . . . . . . 52
6.11. Connection Migration . . . . . . . . . . . . . . . . . . 51 6.10.3. Completion . . . . . . . . . . . . . . . . . . . . . 52
6.11.1. Probing a New Path . . . . . . . . . . . . . . . . . 51 6.10.4. Abandonment . . . . . . . . . . . . . . . . . . . . 53
6.11.2. Initiating Connection Migration . . . . . . . . . . 52 6.11. Connection Migration . . . . . . . . . . . . . . . . . . 53
6.11.3. Responding to Connection Migration . . . . . . . . . 52 6.11.1. Probing a New Path . . . . . . . . . . . . . . . . . 54
6.11.4. Loss Detection and Congestion Control . . . . . . . 54 6.11.2. Initiating Connection Migration . . . . . . . . . . 54
6.11.5. Privacy Implications of Connection Migration . . . . 55 6.11.3. Responding to Connection Migration . . . . . . . . . 55
6.12. Server's Preferred Address . . . . . . . . . . . . . . . 55 6.11.4. Loss Detection and Congestion Control . . . . . . . 56
6.12.1. Communicating A Preferred Address . . . . . . . . . 56 6.11.5. Privacy Implications of Connection Migration . . . . 57
6.12.2. Responding to Connection Migration . . . . . . . . . 56 6.12. Server's Preferred Address . . . . . . . . . . . . . . . 58
6.12.1. Communicating A Preferred Address . . . . . . . . . 59
6.12.2. Responding to Connection Migration . . . . . . . . . 59
6.12.3. Interaction of Client Migration and Preferred 6.12.3. Interaction of Client Migration and Preferred
Address . . . . . . . . . . . . . . . . . . . . . . 56 Address . . . . . . . . . . . . . . . . . . . . . . 59
6.13. Connection Termination . . . . . . . . . . . . . . . . . 57 6.13. Connection Termination . . . . . . . . . . . . . . . . . 60
6.13.1. Closing and Draining Connection States . . . . . . . 57 6.13.1. Closing and Draining Connection States . . . . . . . 60
6.13.2. Idle Timeout . . . . . . . . . . . . . . . . . . . . 58 6.13.2. Idle Timeout . . . . . . . . . . . . . . . . . . . . 61
6.13.3. Immediate Close . . . . . . . . . . . . . . . . . . 59 6.13.3. Immediate Close . . . . . . . . . . . . . . . . . . 62
6.13.4. Stateless Reset . . . . . . . . . . . . . . . . . . 60 6.13.4. Stateless Reset . . . . . . . . . . . . . . . . . . 63
7. Frame Types and Formats . . . . . . . . . . . . . . . . . . . 64 7. Frame Types and Formats . . . . . . . . . . . . . . . . . . . 67
7.1. Variable-Length Integer Encoding . . . . . . . . . . . . 64 7.1. Variable-Length Integer Encoding . . . . . . . . . . . . 67
7.2. PADDING Frame . . . . . . . . . . . . . . . . . . . . . . 65 7.2. PADDING Frame . . . . . . . . . . . . . . . . . . . . . . 68
7.3. RST_STREAM Frame . . . . . . . . . . . . . . . . . . . . 65 7.3. RST_STREAM Frame . . . . . . . . . . . . . . . . . . . . 68
7.4. CONNECTION_CLOSE frame . . . . . . . . . . . . . . . . . 66 7.4. CONNECTION_CLOSE frame . . . . . . . . . . . . . . . . . 69
7.5. APPLICATION_CLOSE frame . . . . . . . . . . . . . . . . . 67 7.5. APPLICATION_CLOSE frame . . . . . . . . . . . . . . . . . 70
7.6. MAX_DATA Frame . . . . . . . . . . . . . . . . . . . . . 68 7.6. MAX_DATA Frame . . . . . . . . . . . . . . . . . . . . . 71
7.7. MAX_STREAM_DATA Frame . . . . . . . . . . . . . . . . . . 69 7.7. MAX_STREAM_DATA Frame . . . . . . . . . . . . . . . . . . 72
7.8. MAX_STREAM_ID Frame . . . . . . . . . . . . . . . . . . . 70 7.8. MAX_STREAM_ID Frame . . . . . . . . . . . . . . . . . . . 73
7.9. PING Frame . . . . . . . . . . . . . . . . . . . . . . . 70 7.9. PING Frame . . . . . . . . . . . . . . . . . . . . . . . 73
7.10. BLOCKED Frame . . . . . . . . . . . . . . . . . . . . . . 71 7.10. BLOCKED Frame . . . . . . . . . . . . . . . . . . . . . . 74
7.11. STREAM_BLOCKED Frame . . . . . . . . . . . . . . . . . . 71 7.11. STREAM_BLOCKED Frame . . . . . . . . . . . . . . . . . . 74
7.12. STREAM_ID_BLOCKED Frame . . . . . . . . . . . . . . . . . 72 7.12. STREAM_ID_BLOCKED Frame . . . . . . . . . . . . . . . . . 75
7.13. NEW_CONNECTION_ID Frame . . . . . . . . . . . . . . . . . 72 7.13. NEW_CONNECTION_ID Frame . . . . . . . . . . . . . . . . . 75
7.14. STOP_SENDING Frame . . . . . . . . . . . . . . . . . . . 74 7.14. RETIRE_CONNECTION_ID Frame . . . . . . . . . . . . . . . 77
7.15. ACK Frame . . . . . . . . . . . . . . . . . . . . . . . . 74 7.15. STOP_SENDING Frame . . . . . . . . . . . . . . . . . . . 77
7.15.1. ACK Block Section . . . . . . . . . . . . . . . . . 76 7.16. ACK Frame . . . . . . . . . . . . . . . . . . . . . . . . 78
7.15.2. Sending ACK Frames . . . . . . . . . . . . . . . . . 77 7.16.1. ACK Block Section . . . . . . . . . . . . . . . . . 79
7.15.3. ACK Frames and Packet Protection . . . . . . . . . . 78 7.16.2. ECN section . . . . . . . . . . . . . . . . . . . . 81
7.16. ACK_ECN Frame . . . . . . . . . . . . . . . . . . . . . . 78 7.16.3. Sending ACK Frames . . . . . . . . . . . . . . . . . 82
7.17. PATH_CHALLENGE Frame . . . . . . . . . . . . . . . . . . 79 7.16.4. ACK Frames and Packet Protection . . . . . . . . . . 83
7.18. PATH_RESPONSE Frame . . . . . . . . . . . . . . . . . . . 80 7.17. PATH_CHALLENGE Frame . . . . . . . . . . . . . . . . . . 83
7.19. NEW_TOKEN frame . . . . . . . . . . . . . . . . . . . . . 80 7.18. PATH_RESPONSE Frame . . . . . . . . . . . . . . . . . . . 84
7.20. STREAM Frames . . . . . . . . . . . . . . . . . . . . . . 80 7.19. NEW_TOKEN frame . . . . . . . . . . . . . . . . . . . . . 84
7.21. CRYPTO Frame . . . . . . . . . . . . . . . . . . . . . . 82 7.20. STREAM Frames . . . . . . . . . . . . . . . . . . . . . . 84
8. Packetization and Reliability . . . . . . . . . . . . . . . . 83 7.21. CRYPTO Frame . . . . . . . . . . . . . . . . . . . . . . 86
8.1. Packet Processing and Acknowledgment . . . . . . . . . . 84 8. Packetization and Reliability . . . . . . . . . . . . . . . . 87
8.2. Retransmission of Information . . . . . . . . . . . . . . 84 8.1. Packet Processing and Acknowledgment . . . . . . . . . . 87
8.3. Packet Size . . . . . . . . . . . . . . . . . . . . . . . 86 8.2. Retransmission of Information . . . . . . . . . . . . . . 88
8.4. Path Maximum Transmission Unit . . . . . . . . . . . . . 87 8.3. Packet Size . . . . . . . . . . . . . . . . . . . . . . . 90
8.4.1. IPv4 PMTU Discovery . . . . . . . . . . . . . . . . . 87 8.4. Path Maximum Transmission Unit . . . . . . . . . . . . . 90
8.4.1. IPv4 PMTU Discovery . . . . . . . . . . . . . . . . . 91
8.4.2. Special Considerations for Packetization Layer PMTU 8.4.2. Special Considerations for Packetization Layer PMTU
Discovery . . . . . . . . . . . . . . . . . . . . . . 88 Discovery . . . . . . . . . . . . . . . . . . . . . . 92
9. Streams: QUIC's Data Structuring Abstraction . . . . . . . . 88 9. Streams: QUIC's Data Structuring Abstraction . . . . . . . . 92
9.1. Stream Identifiers . . . . . . . . . . . . . . . . . . . 89 9.1. Stream Identifiers . . . . . . . . . . . . . . . . . . . 93
9.2. Stream States . . . . . . . . . . . . . . . . . . . . . . 90 9.2. Stream States . . . . . . . . . . . . . . . . . . . . . . 94
9.2.1. Send Stream States . . . . . . . . . . . . . . . . . 91 9.2.1. Send Stream States . . . . . . . . . . . . . . . . . 95
9.2.2. Receive Stream States . . . . . . . . . . . . . . . . 93 9.2.2. Receive Stream States . . . . . . . . . . . . . . . . 97
9.2.3. Permitted Frame Types . . . . . . . . . . . . . . . . 96 9.2.3. Permitted Frame Types . . . . . . . . . . . . . . . . 99
9.2.4. Bidirectional Stream States . . . . . . . . . . . . . 96 9.2.4. Bidirectional Stream States . . . . . . . . . . . . . 99
9.3. Solicited State Transitions . . . . . . . . . . . . . . . 97 9.3. Solicited State Transitions . . . . . . . . . . . . . . . 101
9.4. Stream Concurrency . . . . . . . . . . . . . . . . . . . 98 9.4. Stream Concurrency . . . . . . . . . . . . . . . . . . . 101
9.5. Sending and Receiving Data . . . . . . . . . . . . . . . 99 9.5. Sending and Receiving Data . . . . . . . . . . . . . . . 102
9.6. Stream Prioritization . . . . . . . . . . . . . . . . . . 99 9.6. Stream Prioritization . . . . . . . . . . . . . . . . . . 102
10. Flow Control . . . . . . . . . . . . . . . . . . . . . . . . 100 10. Flow Control . . . . . . . . . . . . . . . . . . . . . . . . 103
10.1. Edge Cases and Other Considerations . . . . . . . . . . 101 10.1. Edge Cases and Other Considerations . . . . . . . . . . 105
10.1.1. Response to a RST_STREAM . . . . . . . . . . . . . . 102 10.1.1. Response to a RST_STREAM . . . . . . . . . . . . . . 105
10.1.2. Data Limit Increments . . . . . . . . . . . . . . . 102 10.1.2. Data Limit Increments . . . . . . . . . . . . . . . 105
10.2. Stream Limit Increment . . . . . . . . . . . . . . . . . 103 10.2. Stream Limit Increment . . . . . . . . . . . . . . . . . 106
10.2.1. Blocking on Flow Control . . . . . . . . . . . . . . 103 10.2.1. Blocking on Flow Control . . . . . . . . . . . . . . 106
10.3. Stream Final Offset . . . . . . . . . . . . . . . . . . 103 10.3. Stream Final Offset . . . . . . . . . . . . . . . . . . 107
10.4. Flow Control for Cryptographic Handshake . . . . . . . . 104 10.4. Flow Control for Cryptographic Handshake . . . . . . . . 107
11. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 104 11. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 107
11.1. Connection Errors . . . . . . . . . . . . . . . . . . . 104 11.1. Connection Errors . . . . . . . . . . . . . . . . . . . 108
11.2. Stream Errors . . . . . . . . . . . . . . . . . . . . . 105 11.2. Stream Errors . . . . . . . . . . . . . . . . . . . . . 108
11.3. Transport Error Codes . . . . . . . . . . . . . . . . . 105 11.3. Transport Error Codes . . . . . . . . . . . . . . . . . 109
11.4. Application Protocol Error Codes . . . . . . . . . . . . 107 11.4. Application Protocol Error Codes . . . . . . . . . . . . 110
12. Security Considerations . . . . . . . . . . . . . . . . . . . 107 12. Security Considerations . . . . . . . . . . . . . . . . . . . 110
12.1. Handshake Denial of Service . . . . . . . . . . . . . . 107 12.1. Handshake Denial of Service . . . . . . . . . . . . . . 110
12.2. Spoofed ACK Attack . . . . . . . . . . . . . . . . . . . 108 12.2. Spoofed ACK Attack . . . . . . . . . . . . . . . . . . . 111
12.3. Optimistic ACK Attack . . . . . . . . . . . . . . . . . 109 12.3. Optimistic ACK Attack . . . . . . . . . . . . . . . . . 112
12.4. Slowloris Attacks . . . . . . . . . . . . . . . . . . . 109 12.4. Slowloris Attacks . . . . . . . . . . . . . . . . . . . 112
12.5. Stream Fragmentation and Reassembly Attacks . . . . . . 109 12.5. Stream Fragmentation and Reassembly Attacks . . . . . . 113
12.6. Stream Commitment Attack . . . . . . . . . . . . . . . . 110 12.6. Stream Commitment Attack . . . . . . . . . . . . . . . . 113
12.7. Explicit Congestion Notification Attacks . . . . . . . . 110 12.7. Explicit Congestion Notification Attacks . . . . . . . . 114
12.8. Stateless Reset Oracle . . . . . . . . . . . . . . . . . 110 12.8. Stateless Reset Oracle . . . . . . . . . . . . . . . . . 114
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 111 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 114
13.1. QUIC Transport Parameter Registry . . . . . . . . . . . 111 13.1. QUIC Transport Parameter Registry . . . . . . . . . . . 114
13.2. QUIC Frame Type Registry . . . . . . . . . . . . . . . . 112 13.2. QUIC Frame Type Registry . . . . . . . . . . . . . . . . 116
13.3. QUIC Transport Error Codes Registry . . . . . . . . . . 113 13.3. QUIC Transport Error Codes Registry . . . . . . . . . . 117
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 115 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 120
14.1. Normative References . . . . . . . . . . . . . . . . . . 115 14.1. Normative References . . . . . . . . . . . . . . . . . . 120
14.2. Informative References . . . . . . . . . . . . . . . . . 116 14.2. Informative References . . . . . . . . . . . . . . . . . 121
Appendix A. Sample Packet Number Decoding Algorithm . . . . . . 117 Appendix A. Sample Packet Number Decoding Algorithm . . . . . . 122
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 118 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 123
B.1. Since draft-ietf-quic-transport-13 . . . . . . . . . . . 118 B.1. Since draft-ietf-quic-transport-14 . . . . . . . . . . . 123
B.2. Since draft-ietf-quic-transport-12 . . . . . . . . . . . 119 B.2. Since draft-ietf-quic-transport-13 . . . . . . . . . . . 124
B.3. Since draft-ietf-quic-transport-11 . . . . . . . . . . . 120 B.3. Since draft-ietf-quic-transport-12 . . . . . . . . . . . 124
B.4. Since draft-ietf-quic-transport-10 . . . . . . . . . . . 120 B.4. Since draft-ietf-quic-transport-11 . . . . . . . . . . . 125
B.5. Since draft-ietf-quic-transport-09 . . . . . . . . . . . 121 B.5. Since draft-ietf-quic-transport-10 . . . . . . . . . . . 126
B.6. Since draft-ietf-quic-transport-08 . . . . . . . . . . . 121 B.6. Since draft-ietf-quic-transport-09 . . . . . . . . . . . 126
B.7. Since draft-ietf-quic-transport-07 . . . . . . . . . . . 122 B.7. Since draft-ietf-quic-transport-08 . . . . . . . . . . . 127
B.8. Since draft-ietf-quic-transport-06 . . . . . . . . . . . 123 B.8. Since draft-ietf-quic-transport-07 . . . . . . . . . . . 127
B.9. Since draft-ietf-quic-transport-05 . . . . . . . . . . . 123 B.9. Since draft-ietf-quic-transport-06 . . . . . . . . . . . 128
B.10. Since draft-ietf-quic-transport-04 . . . . . . . . . . . 124 B.10. Since draft-ietf-quic-transport-05 . . . . . . . . . . . 129
B.11. Since draft-ietf-quic-transport-03 . . . . . . . . . . . 124 B.11. Since draft-ietf-quic-transport-04 . . . . . . . . . . . 129
B.12. Since draft-ietf-quic-transport-02 . . . . . . . . . . . 125 B.12. Since draft-ietf-quic-transport-03 . . . . . . . . . . . 130
B.13. Since draft-ietf-quic-transport-01 . . . . . . . . . . . 126 B.13. Since draft-ietf-quic-transport-02 . . . . . . . . . . . 130
B.14. Since draft-ietf-quic-transport-00 . . . . . . . . . . . 128 B.14. Since draft-ietf-quic-transport-01 . . . . . . . . . . . 131
B.15. Since draft-hamilton-quic-transport-protocol-01 . . . . . 128 B.15. Since draft-ietf-quic-transport-00 . . . . . . . . . . . 133
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 128 B.16. Since draft-hamilton-quic-transport-protocol-01 . . . . . 133
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 128 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 133
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 129 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 134
1. Introduction 1. Introduction
QUIC is a multiplexed and secure transport protocol that runs on top QUIC is a multiplexed and secure transport protocol that runs on top
of UDP. QUIC aims to provide a flexible set of features that allow of UDP. QUIC aims to provide a flexible set of features that allow
it to be a general-purpose secure transport for multiple it to be a general-purpose secure transport for multiple
applications. applications.
o Version negotiation o Version negotiation
skipping to change at page 5, line 47 skipping to change at page 6, line 4
1. Introduction 1. Introduction
QUIC is a multiplexed and secure transport protocol that runs on top QUIC is a multiplexed and secure transport protocol that runs on top
of UDP. QUIC aims to provide a flexible set of features that allow of UDP. QUIC aims to provide a flexible set of features that allow
it to be a general-purpose secure transport for multiple it to be a general-purpose secure transport for multiple
applications. applications.
o Version negotiation o Version negotiation
o Low-latency connection establishment o Low-latency connection establishment
o Authenticated and encrypted header and payload o Authenticated and encrypted header and payload
o Stream multiplexing o Stream multiplexing
o Stream and connection-level flow control o Stream and connection-level flow control
o Connection migration and resilience to NAT rebinding o Connection migration and resilience to NAT rebinding
QUIC implements techniques learned from experience with TCP, SCTP and QUIC uses UDP as a substrate to avoid requiring changes in legacy
other transport protocols. QUIC uses UDP as substrate so as to not client operating systems and middleboxes. QUIC authenticates all of
require changes to legacy client operating systems and middleboxes to its headers and encrypts most of the data it exchanges, including its
be deployable. QUIC authenticates all of its headers and encrypts signaling. This allows the protocol to evolve without incurring a
most of the data it exchanges, including its signaling. This allows dependency on upgrades to middleboxes.
the protocol to evolve without incurring a dependency on upgrades to
middleboxes. This document describes the core QUIC protocol, This document describes the core QUIC protocol, including the
including the conceptual design, wire format, and mechanisms of the conceptual design, wire format, and mechanisms of the QUIC protocol
QUIC protocol for connection establishment, stream multiplexing, for connection establishment, stream multiplexing, stream and
stream and connection-level flow control, connection migration, and connection-level flow control, connection migration, and data
data reliability. reliability.
Accompanying documents describe QUIC's loss detection and congestion Accompanying documents describe QUIC's loss detection and congestion
control [QUIC-RECOVERY], and the use of TLS 1.3 for key negotiation control [QUIC-RECOVERY], and the use of TLS 1.3 for key negotiation
[QUIC-TLS]. [QUIC-TLS].
QUIC version 1 conforms to the protocol invariants in QUIC version 1 conforms to the protocol invariants in
[QUIC-INVARIANTS]. [QUIC-INVARIANTS].
2. Conventions and Definitions 2. Conventions and Definitions
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Stream: A logical, bi-directional channel of ordered bytes within a Stream: A logical, bi-directional channel of ordered bytes within a
QUIC connection. QUIC connection.
Connection: A conversation between two QUIC endpoints with a single Connection: A conversation between two QUIC endpoints with a single
encryption context that multiplexes streams within it. encryption context that multiplexes streams within it.
Connection ID: An opaque identifier that is used to identify a QUIC Connection ID: An opaque identifier that is used to identify a QUIC
connection at an endpoint. Each endpoint sets a value that its connection at an endpoint. Each endpoint sets a value that its
peer includes in packets. peer includes in packets.
QUIC packet: A well-formed UDP payload that can be parsed by a QUIC QUIC packet: The smallest unit of data that can be exchanged by QUIC
receiver. endpoints.
QUIC is a name, not an acronym. QUIC is a name, not an acronym.
2.1. Notational Conventions 2.1. Notational Conventions
Packet and frame diagrams use the format described in Section 3.1 of Packet and frame diagrams use the format described in Section 3.1 of
[RFC2360], with the following additional conventions: [RFC2360], with the following additional conventions:
[x] Indicates that x is optional [x] Indicates that x is optional
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version-independent. The packet number and values for packet types version-independent. The packet number and values for packet types
defined in Table 1 are version-specific. See [QUIC-INVARIANTS] for defined in Table 1 are version-specific. See [QUIC-INVARIANTS] for
details on how packets from different versions of QUIC are details on how packets from different versions of QUIC are
interpreted. interpreted.
The interpretation of the fields and the payload are specific to a The interpretation of the fields and the payload are specific to a
version and packet type. Type-specific semantics for this version version and packet type. Type-specific semantics for this version
are described in the following sections. are described in the following sections.
The end of the packet is determined by the Length field. The Length The end of the packet is determined by the Length field. The Length
field covers the both the Packet Number and Payload fields, both of field covers both the Packet Number and Payload fields, both of which
which are confidentiality protected and initially of unknown length. are confidentiality protected and initially of unknown length. The
The size of the Payload field is learned once the packet number size of the Payload field is learned once the packet number
protection is removed. protection is removed.
Senders can sometimes coalesce multiple packets into one UDP Senders can sometimes coalesce multiple packets into one UDP
datagram. See Section 4.9 for more details. datagram. See Section 4.9 for more details.
4.2. Short Header 4.2. Short Header
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
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Third Bit: The third bit (0x20) of octet 0 is set to 1. Third Bit: The third bit (0x20) of octet 0 is set to 1.
[[Editor's Note: this section should be removed and the bit [[Editor's Note: this section should be removed and the bit
definitions changed before this draft goes to the IESG.]] definitions changed before this draft goes to the IESG.]]
Fourth Bit: The fourth bit (0x10) of octet 0 is set to 1. Fourth Bit: The fourth bit (0x10) of octet 0 is set to 1.
[[Editor's Note: this section should be removed and the bit [[Editor's Note: this section should be removed and the bit
definitions changed before this draft goes to the IESG.]] definitions changed before this draft goes to the IESG.]]
Google QUIC Demultipexing Bit: The fifth bit (0x8) of octet 0 is set Google QUIC Demultiplexing Bit: The fifth bit (0x8) of octet 0 is
to 0. This allows implementations of Google QUIC to distinguish set to 0. This allows implementations of Google QUIC to
Google QUIC packets from short header packets sent by a client distinguish Google QUIC packets from short header packets sent by
because Google QUIC servers expect the connection ID to always be a client because Google QUIC servers expect the connection ID to
present. The special interpretation of this bit SHOULD be removed always be present. The special interpretation of this bit SHOULD
from this specification when Google QUIC has finished be removed from this specification when Google QUIC has finished
transitioning to the new header format. transitioning to the new header format.
Reserved: The sixth, seventh, and eighth bits (0x7) of octet 0 are Reserved: The sixth, seventh, and eighth bits (0x7) of octet 0 are
reserved for experimentation. Endpoints MUST ignore these bits on reserved for experimentation. Endpoints MUST ignore these bits on
packets they receive unless they are participating in an packets they receive unless they are participating in an
experiment that uses these bits. An endpoint not actively using experiment that uses these bits. An endpoint not actively using
these bits SHOULD set the value randomly on packets they send to these bits SHOULD set the value randomly on packets they send to
protect against unwanted inference about particular values. protect against unwanted inference about particular values.
Destination Connection ID: The Destination Connection ID is a Destination Connection ID: The Destination Connection ID is a
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ODCIL(8) | Original Destination Connection ID (*) | | ODCIL(8) | Original Destination Connection ID (*) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Retry Token (*) ... | Retry Token (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Retry Packet Figure 4: Retry Packet
A Retry packet (shown in Figure 4) only uses the invariant portion of A Retry packet (shown in Figure 4) only uses the invariant portion of
the long packet header [QUIC-INVARIANTS]; that is, the fields up to the long packet header [QUIC-INVARIANTS]; that is, the fields up to
and including the Destination and Source Connection ID fields. The and including the Destination and Source Connection ID fields. A
contents of the Retry packet are not protected. Like Version Retry packet does not contain any protected fields. Like Version
Negotiation, a Retry packet contains the long header including the Negotiation, a Retry packet contains the long header including the
connection IDs, but omits the Length, Packet Number, and Payload connection IDs, but omits the Length, Packet Number, and Payload
fields. These are replaced with: fields. These are replaced with:
ODCIL: The length of the Original Destination Connection ID field. ODCIL: The length of the Original Destination Connection ID field.
The length is encoded in the least significant 4 bits of the The length is encoded in the least significant 4 bits of the
octet, using the same encoding as the DCIL and SCIL fields. The octet, using the same encoding as the DCIL and SCIL fields. The
most significant 4 bits of this octet are reserved. Unless a use most significant 4 bits of this octet are reserved. Unless a use
for these bits has been negotiated, endpoints SHOULD send for these bits has been negotiated, endpoints SHOULD send
randomized values and MUST ignore any value that it receives. randomized values and MUST ignore any value that it receives.
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length of this field is given in ODCIL. length of this field is given in ODCIL.
Retry Token: An opaque token that the server can use to validate the Retry Token: An opaque token that the server can use to validate the
client's address. client's address.
The server populates the Destination Connection ID with the The server populates the Destination Connection ID with the
connection ID that the client included in the Source Connection ID of connection ID that the client included in the Source Connection ID of
the Initial packet. the Initial packet.
The server includes a connection ID of its choice in the Source The server includes a connection ID of its choice in the Source
Connection ID field. The client MUST use this connection ID in the Connection ID field. This value MUST not be equal to the Destination
Destination Connection ID of subsequent packets that it sends. Connection ID field of the packet sent by the client. The client
MUST use this connection ID in the Destination Connection ID of
subsequent packets that it sends.
A Retry packet does not include a packet number and cannot be A server MAY send Retry packets in response to Initial and 0-RTT
explicitly acknowledged by a client. packets. A server can either discard or buffer 0-RTT packets that it
receives. A server can send multiple Retry packets as it receives
Initial or 0-RTT packets.
A server MUST NOT send a Retry in response to packets other than A client MUST accept and process at most one Retry packet for each
Initial or 0-RTT packets. A server MAY choose to only send Retry in connection attempt. After the client has received and processed an
response to Initial packets and discard or buffer 0-RTT packets Initial or Retry packet from the server, it MUST discard any
corresponding to unvalidated client addresses. subsequent Retry packets that it receives.
If the Original Destination Connection ID field does not match the Clients MUST discard Retry packets that contain an Original
Destination Connection ID from the most recent Initial packet it Destination Connection ID field that does not match the Destination
sent, clients MUST discard the packet. This prevents an off-path Connection ID from its Initial packet. This prevents an off-path
attacker from injecting a Retry packet. attacker from injecting a Retry packet.
The client responds to a Retry packet with an Initial packet that The client responds to a Retry packet with an Initial packet that
includes the provided Retry Token to continue connection includes the provided Retry Token to continue connection
establishment. establishment.
A client sets the Destination Connection ID field of this Initial
packet to the value from the Source Connection ID in the Retry
packet. Changing Destination Connection ID also results in a change
to the keys used to protect the Initial packet. It also sets the
Token field to the token provided in the Retry. The client MUST NOT
change the Source Connection ID because the server could include the
connection ID as part of its token validation logic (see
Section 4.6.2).
All subsequent Initial packets from the client MUST use the
connection ID and token values from the Retry packet. Aside from
this, the Initial packet sent by the client is subject to the same
restrictions as the first Initial packet. A client can either reuse
the cryptographic handshake message or construct a new one at its
discretion.
A client MAY attempt 0-RTT after receiving a Retry packet by sending A client MAY attempt 0-RTT after receiving a Retry packet by sending
0-RTT packets to the connection ID provided by the server. A client 0-RTT packets to the connection ID provided by the server. A client
that sends additional 0-RTT packets MUST NOT reset the packet number that sends additional 0-RTT packets without constructing a new
to 0 after a Retry packet, see Section 4.6.4. cryptographic handshake message MUST NOT reset the packet number to 0
after a Retry packet, see Section 4.6.4.
A server that might send another Retry packet in response to a A server acknowledges the use of a Retry packet for a connection
subsequent Initial packet MUST set the Source Connection ID to a new using the original_connection_id transport parameter (see
value of at least 8 octets in length. This allows clients to Section 6.6.1). If the server sends a Retry packet, it MUST include
distinguish between Retry packets when the server sends multiple the value of the Original Destination Connection ID field of the
rounds of Retry packets. Consequently, a valid Retry packet will Retry packet (that is, the Destination Connection ID field from the
always have an Original Destination Connection ID that is at least 8 client's first Initial packet) in the transport parameter.
octets long; clients MUST discard Retry packets that include a
shorter value. A server that will not send additional Retry packets If the client received and processed a Retry packet, it validates
can set the Source Connection ID to any value. that the original_connection_id transport parameter is present and
correct; otherwise, it validates that the transport parameter is
absent. A client MUST treat a failed validation as a connection
error of type TRANSPORT_PARAMETER_ERROR.
A Retry packet does not include a packet number and cannot be
explicitly acknowledged by a client.
4.5. Cryptographic Handshake Packets 4.5. Cryptographic Handshake Packets
Once version negotiation is complete, the cryptographic handshake is Once version negotiation is complete, the cryptographic handshake is
used to agree on cryptographic keys. The cryptographic handshake is used to agree on cryptographic keys. The cryptographic handshake is
carried in Initial (Section 4.6) and Handshake (Section 4.7) packets. carried in Initial (Section 4.6) and Handshake (Section 4.7) packets.
All these packets use the long header and contain the current QUIC All these packets use the long header and contain the current QUIC
version in the version field. version in the version field.
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message needs to be created, such as the packets sent after receiving message needs to be created, such as the packets sent after receiving
a Version Negotiation (Section 4.3) or Retry packet (Section 4.4). a Version Negotiation (Section 4.3) or Retry packet (Section 4.4).
A server sends its first Initial packet in response to a client A server sends its first Initial packet in response to a client
Initial. A server may send multiple Initial packets. The Initial. A server may send multiple Initial packets. The
cryptographic key exchange could require multiple round trips or cryptographic key exchange could require multiple round trips or
retransmissions of this data. retransmissions of this data.
The payload of an Initial packet includes a CRYPTO frame (or frames) The payload of an Initial packet includes a CRYPTO frame (or frames)
containing a cryptographic handshake message, ACK frames, or both. containing a cryptographic handshake message, ACK frames, or both.
PADDING frames are also permitted. The first CRYPTO frame sent PADDING and CONNECTION_CLOSE frames are also permitted. An endpoint
always begins at an offset of 0 (see Section 6.4). that receives an Initial packet containing other frames can either
discard the packet as spurious or treat it as a connection error.
The first packet sent by a client always includes a CRYPTO frame that The first packet sent by a client always includes a CRYPTO frame that
contains the entirety of the first cryptographic handshake message. contains the entirety of the first cryptographic handshake message.
This packet, and the cryptographic handshake message, MUST fit in a This packet, and the cryptographic handshake message, MUST fit in a
single UDP datagram (see Section 6.4). single UDP datagram (see Section 6.4). The first CRYPTO frame sent
always begins at an offset of 0 (see Section 6.4).
Note that if the server sends a HelloRetryRequest, the client will Note that if the server sends a HelloRetryRequest, the client will
send a second Initial packet. This Initial packet will continue the send a second Initial packet. This Initial packet will continue the
cryptographic handshake and will contain a CRYPTO frame with an cryptographic handshake and will contain a CRYPTO frame with an
offset matching the size of the CRYPTO frame sent in the first offset matching the size of the CRYPTO frame sent in the first
Initial packet. Cryptographic handshake messages subsequent to the Initial packet. Cryptographic handshake messages subsequent to the
first do not need to fit within a single UDP datagram. first do not need to fit within a single UDP datagram.
4.6.1. Connection IDs 4.6.1. Connection IDs
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The Destination Connection ID field in the server's Initial packet The Destination Connection ID field in the server's Initial packet
contains a connection ID that is chosen by the recipient of the contains a connection ID that is chosen by the recipient of the
packet (i.e., the client); the Source Connection ID includes the packet (i.e., the client); the Source Connection ID includes the
connection ID that the sender of the packet wishes to use (see connection ID that the sender of the packet wishes to use (see
Section 6.1). The server MUST use consistent Source Connection IDs Section 6.1). The server MUST use consistent Source Connection IDs
during the handshake. during the handshake.
On first receiving an Initial or Retry packet from the server, the On first receiving an Initial or Retry packet from the server, the
client uses the Source Connection ID supplied by the server as the client uses the Source Connection ID supplied by the server as the
Destination Connection ID for subsequent packets. Once a client has Destination Connection ID for subsequent packets. That means that a
received an Initial packet from the server, it MUST discard any client might change the Destination Connection ID twice during
packet it receives with a different Source Connection ID. connection establishment. Once a client has received an Initial
packet from the server, it MUST discard any packet it receives with a
different Source Connection ID.
4.6.2. Tokens 4.6.2. Tokens
If the client has a token received in a NEW_TOKEN frame on a previous If the client has a token received in a NEW_TOKEN frame on a previous
connection to what it believes to be the same server, it can include connection to what it believes to be the same server, it can include
that value in the Token field of its Initial packet. that value in the Token field of its Initial packet.
A token allows a server to correlate activity between connections. A token allows a server to correlate activity between connections.
Specifically, the connection where the token was issued, and any Specifically, the connection where the token was issued, and any
connection where it is used. Clients that want to break continuity connection where it is used. Clients that want to break continuity
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discarded. discarded.
A client SHOULD NOT reuse a token. Reusing a token allows A client SHOULD NOT reuse a token. Reusing a token allows
connections to be linked by entities on the network path (see connections to be linked by entities on the network path (see
Section 6.11.5). A client MUST NOT reuse a token if it believes that Section 6.11.5). A client MUST NOT reuse a token if it believes that
its point of network attachment has changed since the token was last its point of network attachment has changed since the token was last
used; that is, if there is a change in its local IP address or used; that is, if there is a change in its local IP address or
network interface. A client needs to start the connection process network interface. A client needs to start the connection process
over if it migrates prior to completing the handshake. over if it migrates prior to completing the handshake.
If the client received a Retry packet from the server and sends an
Initial packet in response, then it sets the Destination Connection
ID to the value from the Source Connection ID in the Retry packet.
Changing Destination Connection ID also results in a change to the
keys used to protect the Initial packet. It also sets the Token
field to the token provided in the Retry. The client MUST NOT change
the Source Connection ID because the server could include the
connection ID as part of its token validation logic.
When a server receives an Initial packet with an address validation When a server receives an Initial packet with an address validation
token, it SHOULD attempt to validate it. If the token is invalid token, it SHOULD attempt to validate it. If the token is invalid
then the server SHOULD proceed as if the client did not have a then the server SHOULD proceed as if the client did not have a
validated address, including potentially sending a Retry. If the validated address, including potentially sending a Retry. If the
validation succeeds, the server SHOULD then allow the handshake to validation succeeds, the server SHOULD then allow the handshake to
proceed (see Section 6.7). proceed (see Section 6.7).
Note: The rationale for treating the client as unvalidated rather Note: The rationale for treating the client as unvalidated rather
than discarding the packet is that the client might have received than discarding the packet is that the client might have received
the token in a previous connection using the NEW_TOKEN frame, and the token in a previous connection using the NEW_TOKEN frame, and
if the server has lost state, it might be unable to validate the if the server has lost state, it might be unable to validate the
token at all, leading to connection failure if the packet is token at all, leading to connection failure if the packet is
discarded. A server MAY encode tokens provided with NEW_TOKEN discarded. A server MAY encode tokens provided with NEW_TOKEN
frames and Retry packets differently, and validate the latter more frames and Retry packets differently, and validate the latter more
strictly. strictly.
In a stateless design, a server can use encrypted and authenticated
tokens to pass information to clients that the server can later
recover and use to validate a client address. Tokens are not
integrated into the cryptographic handshake and so they are not
authenticated. For instance, a client might be able to reuse a
token. To avoid attacks that exploit this property, a server can
limit its use of tokens to only the information needed validate
client addresses.
4.6.3. Starting Packet Numbers 4.6.3. Starting Packet Numbers
The first Initial packet sent by either endpoint contains a packet The first Initial packet sent by either endpoint contains a packet
number of 0. The packet number MUST increase monotonically number of 0. The packet number MUST increase monotonically
thereafter. Initial packets are in a different packet number space thereafter. Initial packets are in a different packet number space
to other packets (see Section 4.11). to other packets (see Section 4.11).
4.6.4. 0-RTT Packet Numbers 4.6.4. 0-RTT Packet Numbers
Packet numbers for 0-RTT protected packets use the same space as Packet numbers for 0-RTT protected packets use the same space as
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that changes the connection ID used for subsequent packets, indicates that changes the connection ID used for subsequent packets, indicates
a strong possibility that 0-RTT packets could be lost. A client only a strong possibility that 0-RTT packets could be lost. A client only
receives acknowledgments for its 0-RTT packets once the handshake is receives acknowledgments for its 0-RTT packets once the handshake is
complete. Consequently, a server might expect 0-RTT packets to start complete. Consequently, a server might expect 0-RTT packets to start
with a packet number of 0. Therefore, in determining the length of with a packet number of 0. Therefore, in determining the length of
the packet number encoding for 0-RTT packets, a client MUST assume the packet number encoding for 0-RTT packets, a client MUST assume
that all packets up to the current packet number are in flight, that all packets up to the current packet number are in flight,
starting from a packet number of 0. Thus, 0-RTT packets could need starting from a packet number of 0. Thus, 0-RTT packets could need
to use a longer packet number encoding. to use a longer packet number encoding.
A client MAY instead generate a fresh cryptographic handshake message A client SHOULD instead generate a fresh cryptographic handshake
and start packet numbers from 0. This ensures that new 0-RTT packets message and start packet numbers from 0. This ensures that new 0-RTT
will not use the same keys, avoiding any risk of key and nonce reuse; packets will not use the same keys, avoiding any risk of key and
this also prevents 0-RTT packets from previous handshake attempts nonce reuse; this also prevents 0-RTT packets from previous handshake
from being accepted as part of the connection. attempts from being accepted as part of the connection.
4.6.5. Minimum Packet Size 4.6.5. Minimum Packet Size
The payload of a UDP datagram carrying the Initial packet MUST be The payload of a UDP datagram carrying the Initial packet MUST be
expanded to at least 1200 octets (see Section 8), by adding PADDING expanded to at least 1200 octets (see Section 8), by adding PADDING
frames to the Initial packet and/or by combining the Initial packet frames to the Initial packet and/or by combining the Initial packet
with a 0-RTT packet (see Section 4.9). with a 0-RTT packet (see Section 4.9).
4.7. Handshake Packet 4.7. Handshake Packet
skipping to change at page 21, line 26 skipping to change at page 21, line 35
The Destination Connection ID field in a Handshake packet contains a The Destination Connection ID field in a Handshake packet contains a
connection ID that is chosen by the recipient of the packet; the connection ID that is chosen by the recipient of the packet; the
Source Connection ID includes the connection ID that the sender of Source Connection ID includes the connection ID that the sender of
the packet wishes to use (see Section 4.10). the packet wishes to use (see Section 4.10).
The first Handshake packet sent by a server contains a packet number The first Handshake packet sent by a server contains a packet number
of 0. Handshake packets are their own packet number space. Packet of 0. Handshake packets are their own packet number space. Packet
numbers are incremented normally for other Handshake packets. numbers are incremented normally for other Handshake packets.
Servers MUST NOT send more than three datagrams including Initial and Servers MUST NOT send more than three times as many bytes as the
Handshake packets without receiving a packet from a verified source number of bytes received prior to verifying the client's address.
address. Source addresses can be verified through an address Source addresses can be verified through an address validation token
validation token (delivered via a Retry packet or a NEW_TOKEN frame) (delivered via a Retry packet or a NEW_TOKEN frame) or by processing
or by receiving any message from the client encrypted using the any message from the client encrypted using the Handshake keys. This
Handshake keys. limit exists to mitigate amplification attacks.
In order to prevent this limit causing a handshake deadlock, the
client SHOULD always send a packet upon a handshake timeout, as
described in [QUIC-RECOVERY]. If the client has no data to
retransmit and does not have Handshake keys, it SHOULD send an
Initial packet in a UDP datagram of at least 1200 octets. If the
client has Handshake keys, it SHOULD send a Handshake packet.
The payload of this packet contains CRYPTO frames and could contain The payload of this packet contains CRYPTO frames and could contain
PADDING, or ACK frames. Handshake packets MAY contain PADDING, or ACK frames. Handshake packets MAY contain
CONNECTION_CLOSE frames if the handshake is unsuccessful. CONNECTION_CLOSE or APPLICATION_CLOSE frames. Endpoints MUST treat
receipt of Handshake packets with other frames as a connection error.
4.8. Protected Packets 4.8. Protected Packets
All QUIC packets use packet protection. Packets that are protected All QUIC packets use packet protection. Packets that are protected
with the static handshake keys or the 0-RTT keys are sent with long with the static handshake keys or the 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. 0-RTT and 1-RTT protected packets share a single packet protection. 0-RTT and 1-RTT protected packets share a single
packet number space. packet number space.
skipping to change at page 22, line 14 skipping to change at page 22, line 33
Packets protected with 0-RTT and 1-RTT keys are expected to have Packets protected with 0-RTT and 1-RTT keys are expected to have
confidentiality and data origin authentication; the cryptographic confidentiality and data origin authentication; the cryptographic
handshake ensures that only the communicating endpoints receive the handshake ensures that only the communicating endpoints receive the
corresponding keys. corresponding keys.
Packets protected with 0-RTT keys use a type value of 0x7C. The Packets protected with 0-RTT keys use a type value of 0x7C. The
connection ID fields for a 0-RTT packet MUST match the values used in connection ID fields for a 0-RTT packet MUST match the values used in
the Initial packet (Section 4.6). the Initial packet (Section 4.6).
The client can send 0-RTT packets after receiving an Initial
Section 4.6 or Handshake (Section 4.7) packet, if that packet does
not complete the handshake. Even if the client receives a different
connection ID in the Handshake packet, it MUST continue to use the
same Destination Connection ID for 0-RTT packets, see Section 4.10.
The version field for protected packets is the current QUIC version. The version field for protected packets is the current QUIC version.
The packet number field contains a packet number, which has The packet number field contains a packet number, which has
additional confidentiality protection that is applied after packet additional confidentiality protection that is applied after packet
protection is applied (see [QUIC-TLS] for details). The underlying protection is applied (see [QUIC-TLS] for details). The underlying
packet number increases with each packet sent, see Section 4.11 for packet number increases with each packet sent, see Section 4.11 for
details. details.
The payload is protected using authenticated encryption. [QUIC-TLS] The payload is protected using authenticated encryption. [QUIC-TLS]
describes packet protection in detail. After decryption, the describes packet protection in detail. After decryption, the
skipping to change at page 22, line 44 skipping to change at page 23, line 9
A sender can coalesce multiple QUIC packets (typically a A sender can coalesce multiple QUIC packets (typically a
Cryptographic Handshake packet and a Protected packet) into one UDP Cryptographic Handshake packet and a Protected packet) into one UDP
datagram. This can reduce the number of UDP datagrams needed to send datagram. This can reduce the number of UDP datagrams needed to send
application data during the handshake and immediately afterwards. It application data during the handshake and immediately afterwards. It
is not necessary for senders to coalesce packets, though failing to is not necessary for senders to coalesce packets, though failing to
do so will require sending a significantly larger number of datagrams do so will require sending a significantly larger number of datagrams
during the handshake. Receivers MUST be able to process coalesced during the handshake. Receivers MUST be able to process coalesced
packets. packets.
Senders SHOULD coalesce packets in order of increasing encryption Coalescing packets in order of increasing encryption levels (Initial,
levels (Initial, Handshake, 0-RTT, 1-RTT), as this makes it more 0-RTT, Handshake, 1-RTT) makes it more likely the receiver will be
likely the receiver will be able to process all the packets in a able to process all the packets in a single pass. A packet with a
single pass. A packet with a short header does not include a length, short header does not include a length, so it will always be the last
so it will always be the last packet included in a UDP datagram. packet included in a UDP datagram.
Senders MUST NOT coalesce QUIC packets with different Destination Senders MUST NOT coalesce QUIC packets with different Destination
Connection IDs into a single UDP datagram. Receivers SHOULD ignore Connection IDs into a single UDP datagram. Receivers SHOULD ignore
any subsequent packets with a different Destination Connection ID any subsequent packets with a different Destination Connection ID
than the first packet in the datagram. than the first packet in the datagram.
Every QUIC packet that is coalesced into a single UDP datagram is Every QUIC packet that is coalesced into a single UDP datagram is
separate and complete. Though the values of some fields in the separate and complete. Though the values of some fields in the
packet header might be redundant, no fields are omitted. The packet header might be redundant, no fields are omitted. The
receiver of coalesced QUIC packets MUST individually process each receiver of coalesced QUIC packets MUST individually process each
skipping to change at page 23, line 40 skipping to change at page 24, line 5
the peer. the peer.
During the handshake, packets with the long header are used to During the handshake, packets with the long header are used to
establish the connection ID that each endpoint uses. Each endpoint establish the connection ID that each endpoint uses. Each endpoint
uses the Source Connection ID field to specify the connection ID that uses the Source Connection ID field to specify the connection ID that
is used in the Destination Connection ID field of packets being sent is used in the Destination Connection ID field of packets being sent
to them. Upon receiving a packet, each endpoint sets the Destination to them. Upon receiving a packet, each endpoint sets the Destination
Connection ID it sends to match the value of the Source Connection ID Connection ID it sends to match the value of the Source Connection ID
that they receive. that they receive.
During the handshake, an endpoint might receive multiple packets with During the handshake, a client can receive both a Retry and an
the long header, and thus be given multiple opportunities to update Initial packet, and thus be given two opportunities to update the
the Destination Connection ID it sends. A client MUST only change Destination Connection ID it sends. A client MUST only change the
the value it sends in the Destination Connection ID in response to value it sends in the Destination Connection ID in response to the
the first packet of each type it receives from the server (Retry or first packet of each type it receives from the server (Retry or
Initial); a server MUST set its value based on the Initial packet. Initial); a server MUST set its value based on the Initial packet.
Any additional changes are not permitted; if subsequent packets of Any additional changes are not permitted; if subsequent packets of
those types include a different Source Connection ID, they MUST be those types include a different Source Connection ID, they MUST be
discarded. This avoids problems that might arise from stateless discarded. This avoids problems that might arise from stateless
processing of multiple Initial packets producing different connection processing of multiple Initial packets producing different connection
IDs. IDs.
Short headers only include the Destination Connection ID and omit the Short headers only include the Destination Connection ID and omit the
explicit length. The length of the Destination Connection ID field explicit length. The length of the Destination Connection ID field
is expected to be known to endpoints. is expected to be known to endpoints.
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Endpoints using a connection-ID based load balancer could agree with Endpoints using a connection-ID based load balancer could agree with
the load balancer on a fixed or minimum length and on an encoding for the load balancer on a fixed or minimum length and on an encoding for
connection IDs. This fixed portion could encode an explicit length, connection IDs. This fixed portion could encode an explicit length,
which allows the entire connection ID to vary in length and still be which allows the entire connection ID to vary in length and still be
used by the load balancer. used by the load balancer.
The very first packet sent by a client includes a random value for The very first packet sent by a client includes a random value for
Destination Connection ID. The same value MUST be used for all 0-RTT Destination Connection ID. The same value MUST be used for all 0-RTT
packets sent on that connection (Section 4.8). This randomized value packets sent on that connection (Section 4.8). This randomized value
is used to determine the packet protection keys for Initial packets is used to determine the packet protection keys for Initial packets
(see Section 5.1.1 of [QUIC-TLS]). (see Section 5.2 of [QUIC-TLS]).
A Version Negotiation (Section 4.3) packet MUST use both connection A Version Negotiation (Section 4.3) packet MUST use both connection
IDs selected by the client, swapped to ensure correct routing toward IDs selected by the client, swapped to ensure correct routing toward
the client. the client.
The connection ID can change over the lifetime of a connection, The connection ID can change over the lifetime of a connection,
especially in response to connection migration (Section 6.11). especially in response to connection migration (Section 6.11).
NEW_CONNECTION_ID frames (Section 7.13) are used to provide new NEW_CONNECTION_ID frames (Section 7.13) are used to provide new
connection ID values. connection ID values.
4.11. Packet Numbers 4.11. Packet Numbers
The packet number is an integer in the range 0 to 2^62-1. The value The packet number is an integer in the range 0 to 2^62-1. The value
is used in determining the cryptographic nonce for packet encryption. is used in determining the cryptographic nonce for packet protection.
Each endpoint maintains a separate packet number for sending and Each endpoint maintains a separate packet number for sending and
receiving. receiving.
Packet numbers are divided into 3 spaces in QUIC: Packet numbers are divided into 3 spaces in QUIC:
o Initial space: All Initial packets Section 4.6 are in this space. o Initial space: All Initial packets Section 4.6 are in this space.
o Handshake space: All Handshake packets Section 4.7 are in this o Handshake space: All Handshake packets Section 4.7 are in this
space. space.
o Application data space: All 0-RTT and 1-RTT encrypted packets o Application data space: All 0-RTT and 1-RTT encrypted packets
Section 4.8 are in this space. Section 4.8 are in this space.
As described in [QUIC-TLS], each packet type uses different As described in [QUIC-TLS], each packet type uses different
encryption keys. protection keys.
Conceptually, a packet number space is the encryption context in Conceptually, a packet number space is the context in which a packet
which a packet can be processed and ACKed. Initial packets can only can be processed and acknowledged. Initial packets can only be sent
be sent with Initial encryption keys and ACKed in packets which are with Initial packet protection keys and acknowledged in packets which
also Initial packets. Similarly, Handshake packets can only be sent are also Initial packets. Similarly, Handshake packets are sent at
and acknowledged in Handshake packets. the Handshake encryption level and can only be acknowledged in
Handshake packets.
This enforces cryptographic separation between the data sent in the This enforces cryptographic separation between the data sent in the
different packet sequence number spaces. Each packet number space different packet sequence number spaces. Each packet number space
starts at packet number 0. Subsequent packets sent in the same starts at packet number 0. Subsequent packets sent in the same
packet number space MUST increase the packet number by at least one. packet number space MUST increase the packet number by at least one.
0-RTT and 1-RTT data exist in the same packet number space to make 0-RTT and 1-RTT data exist in the same packet number space to make
loss recovery algorithms easier to implement between the two packet loss recovery algorithms easier to implement between the two packet
types. types.
skipping to change at page 25, line 48 skipping to change at page 26, line 24
Table 2: Packet Number Encodings for Packet Headers Table 2: Packet Number Encodings for Packet Headers
Note that these encodings are similar to those in Section 7.1, but Note that these encodings are similar to those in Section 7.1, but
use different values. use different values.
The encoded packet number is protected as described in Section 5.3 The encoded packet number is protected as described in Section 5.3
[QUIC-TLS]. Protection of the packet number is removed prior to [QUIC-TLS]. Protection of the packet number is removed prior to
recovering the full packet number. The full packet number is recovering the full packet number. The full packet number is
reconstructed at the receiver based on the number of significant bits reconstructed at the receiver based on the number of significant bits
present, the content of those bits, and the largest packet number present, the value of those bits, and the largest packet number
received on a successfully authenticated packet. Recovering the full received on a successfully authenticated packet. Recovering the full
packet number is necessary to successfully remove packet protection. packet number is necessary to successfully remove packet protection.
Once packet number protection is removed, the packet number is Once packet number protection is removed, the packet number is
decoded by finding the packet number value that is closest to the decoded by finding the packet number value that is closest to the
next expected packet. The next expected packet is the highest next expected packet. The next expected packet is the highest
received packet number plus one. For example, if the highest received packet number plus one. For example, if the highest
successfully authenticated packet had a packet number of 0xaa82f30e, successfully authenticated packet had a packet number of 0xaa82f30e,
then a packet containing a 14-bit value of 0x9b3 will be decoded as then a packet containing a 14-bit value of 0x9b3 will be decoded as
0xaa8309b3. Example pseudo-code for packet number decoding can be 0xaa8309b3. Example pseudo-code for packet number decoding can be
skipping to change at page 27, line 17 skipping to change at page 27, line 37
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame 1 (*) ... | Frame 1 (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame 2 (*) ... | Frame 2 (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame N (*) ... | Frame N (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Contents of Protected Payload Figure 6: QUIC Payload
Protected payloads MUST contain at least one frame, and MAY contain QUIC payloads MUST contain at least one frame, and MAY contain
multiple frames and multiple frame types. multiple frames and multiple frame types.
Frames MUST fit within a single QUIC packet and MUST NOT span a QUIC Frames MUST fit within a single QUIC packet and MUST NOT span a QUIC
packet boundary. Each frame begins with a Frame Type, indicating its packet boundary. Each frame begins with a Frame Type, indicating its
type, followed by additional type-dependent fields: type, followed by additional type-dependent fields:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame Type (i) ... | Frame Type (i) ...
skipping to change at page 28, line 5 skipping to change at page 29, line 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Generic Frame Layout Figure 7: Generic Frame Layout
The frame types defined in this specification are listed in Table 3. The frame types defined in this specification are listed in Table 3.
The Frame Type in STREAM frames is used to carry other frame-specific The Frame Type in STREAM frames is used to carry other frame-specific
flags. For all other frames, the Frame Type field simply identifies flags. For all other frames, the Frame Type field simply identifies
the frame. These frames are explained in more detail as they are the 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 7.2 | | 0x00 | PADDING | Section 7.2 |
| | | | | | | |
| 0x01 | RST_STREAM | Section 7.3 | | 0x01 | RST_STREAM | Section 7.3 |
| | | | | | | |
| 0x02 | CONNECTION_CLOSE | Section 7.4 | | 0x02 | CONNECTION_CLOSE | Section 7.4 |
| | | | | | | |
| 0x03 | APPLICATION_CLOSE | Section 7.5 | | 0x03 | APPLICATION_CLOSE | Section 7.5 |
| | | | | | | |
| 0x04 | MAX_DATA | Section 7.6 | | 0x04 | MAX_DATA | Section 7.6 |
| | | | | | | |
| 0x05 | MAX_STREAM_DATA | Section 7.7 | | 0x05 | MAX_STREAM_DATA | Section 7.7 |
| | | | | | | |
| 0x06 | MAX_STREAM_ID | Section 7.8 | | 0x06 | MAX_STREAM_ID | Section 7.8 |
| | | | | | | |
| 0x07 | PING | Section 7.9 | | 0x07 | PING | Section 7.9 |
| | | | | | | |
| 0x08 | BLOCKED | Section 7.10 | | 0x08 | BLOCKED | Section 7.10 |
| | | | | | | |
| 0x09 | STREAM_BLOCKED | Section 7.11 | | 0x09 | STREAM_BLOCKED | Section 7.11 |
| | | | | | | |
| 0x0a | STREAM_ID_BLOCKED | Section 7.12 | | 0x0a | STREAM_ID_BLOCKED | Section 7.12 |
| | | | | | | |
| 0x0b | NEW_CONNECTION_ID | Section 7.13 | | 0x0b | NEW_CONNECTION_ID | Section 7.13 |
| | | | | | | |
| 0x0c | STOP_SENDING | Section 7.14 | | 0x0c | STOP_SENDING | Section 7.15 |
| | | | | | | |
| 0x0d | ACK | Section 7.15 | | 0x0d | RETIRE_CONNECTION_ID | Section 7.14 |
| | | | | | | |
| 0x0e | PATH_CHALLENGE | Section 7.17 | | 0x0e | PATH_CHALLENGE | Section 7.17 |
| | | | | | | |
| 0x0f | PATH_RESPONSE | Section 7.18 | | 0x0f | PATH_RESPONSE | Section 7.18 |
| | | | | | | |
| 0x10 - 0x17 | STREAM | Section 7.20 | | 0x10 - 0x17 | STREAM | Section 7.20 |
| | | | | | | |
| 0x18 | CRYPTO | Section 7.21 | | 0x18 | CRYPTO | Section 7.21 |
| | | | | | | |
| 0x19 | NEW_TOKEN | Section 7.19 | | 0x19 | NEW_TOKEN | Section 7.19 |
| | | | | | | |
| 0x1a | ACK_ECN | Section 7.16 | | 0x1a - 0x1b | ACK | Section 7.16 |
+-------------+-------------------+--------------+ +-------------+----------------------+--------------+
Table 3: Frame Types Table 3: Frame Types
All QUIC frames are idempotent. That is, a valid frame does not All QUIC frames are idempotent. That is, a valid frame does not
cause undesirable side effects or errors when received more than cause undesirable side effects or errors when received more than
once. once.
The Frame Type field uses a variable length integer encoding (see The Frame Type field uses a variable length integer encoding (see
Section 7.1) with one exception. To ensure simple and efficient Section 7.1) with one exception. To ensure simple and efficient
implementations of frame parsing, a frame type MUST use the shortest implementations of frame parsing, a frame type MUST use the shortest
possible encoding. Though a two-, four- or eight-octet encoding of possible encoding. Though a two-, four- or eight-octet encoding of
the frame types defined in this document is possible, the Frame Type the frame types defined in this document is possible, the Frame Type
field for these frames are encoded on a single octet. For instance, field for these frames is encoded on a single octet. For instance,
though 0x4007 is a legitimate two-octet encoding for a variable- though 0x4007 is a legitimate two-octet encoding for a variable-
length integer with a value of 7, PING frames are always encoded as a length integer with a value of 7, PING frames are always encoded as a
single octet with the value 0x07. An endpoint MUST treat the receipt single octet with the value 0x07. An endpoint MUST treat the receipt
of a frame type that uses a longer encoding than necessary as a of a frame type that uses a longer encoding than necessary as a
connection error of type PROTOCOL_VIOLATION. connection error of type PROTOCOL_VIOLATION.
5.1. Extension Frames 5.1. Extension Frames
QUIC frames do not use a self-describing encoding. An endpoint QUIC frames do not use a self-describing encoding. An endpoint
therefore needs to understand the syntax of all frames before it can therefore needs to understand the syntax of all frames before it can
successfully process a packet. This allows for efficient encoding of successfully process a packet. This allows for efficient encoding of
frames, but it means that an endpoint cannot send a frame of a type frames, but it means that an endpoint cannot send a frame of a type
that is unknown to its peer. that is unknown to its peer.
An extension to QUIC that wishes to use a new type of frame MUST An extension to QUIC that wishes to use a new type of frame MUST
first ensure that a peer is able to understand the frame. An first ensure that a peer is able to understand the frame. An
endpoint can use a transport parameter to signal its willingness to endpoint can use a transport parameter to signal its willingness to
receive one or more extension frame types with the one transport receive one or more extension frame types with the one transport
parameter. parameter.
Extension frames MUST be congestion controlled and MUST cause an ACK
frame to be sent. The exception is extension frames that replace or
supplement the ACK frame. Extension frames are not included in flow
control unless specified in the extension.
An IANA registry is used to manage the assignment of frame types, see An IANA registry is used to manage the assignment of frame types, see
Section 13.2. Section 13.2.
6. Life of a Connection 6. Life of a Connection
A QUIC connection is a single conversation between two QUIC A QUIC connection is a single conversation between two QUIC
endpoints. QUIC's connection establishment intertwines version endpoints. QUIC's connection establishment intertwines version
negotiation with the cryptographic and transport handshakes to reduce negotiation with the cryptographic and transport handshakes to reduce
connection establishment latency, as described in Section 6.4. Once connection establishment latency, as described in Section 6.4. Once
established, a connection may migrate to a different IP or port at established, a connection may migrate to a different IP or port at
either endpoint, due to NAT rebinding or mobility, as described in either endpoint, due to NAT rebinding or mobility, as described in
Section 6.11. Finally a connection may be terminated by either Section 6.11. Finally, a connection may be terminated by either
endpoint, as described in Section 6.13. endpoint, as described in Section 6.13.
6.1. Connection ID 6.1. Connection ID
Each connection possesses a set of identifiers, any of which could be Each connection possesses a set of identifiers, any of which could be
used to distinguish it from other connections. A connection ID can used to distinguish it from other connections. Connection IDs are
be either 0 octets in length, or between 4 and 18 octets (inclusive). selected independently in each direction. Each Connection ID has an
Connection IDs are selected independently in each direction. associated sequence number to assist in deduplicating messages.
The primary function of a connection ID is to ensure that changes in The primary function of a connection ID is to ensure that changes in
addressing at lower protocol layers (UDP, IP, and below) don't cause addressing at lower protocol layers (UDP, IP, and below) don't cause
packets for a QUIC connection to be delivered to the wrong endpoint. packets for a QUIC connection to be delivered to the wrong endpoint.
Each endpoint selects connection IDs using an implementation-specific Each endpoint selects connection IDs using an implementation-specific
(and perhaps deployment-specific) method which will allow packets (and perhaps deployment-specific) method which will allow packets
with that connection ID to be routed back to the endpoint and with that connection ID to be routed back to the endpoint and
identified by the endpoint upon receipt. identified by the endpoint upon receipt.
Connection IDs MUST NOT contain any information that can be used to
correlate them with other connection IDs for the same connection. As
a trivial example, this means the same connection ID MUST NOT be
issued more than once on the same connection.
A zero-length connection ID MAY be used when the connection ID is not A zero-length connection ID MAY be used when the connection ID is not
needed for routing and the address/port tuple of packets is needed for routing and the address/port tuple of packets is
sufficient to associate them to a connection. An endpoint whose peer sufficient to identify a connection. An endpoint whose peer has
has selected a zero-length connection ID MUST continue to use a zero- selected a zero-length connection ID MUST continue to use a zero-
length connection ID for the lifetime of the connection and MUST NOT length connection ID for the lifetime of the connection and MUST NOT
send packets from any other local address. send packets from any other local address.
When an endpoint has requested a non-zero-length connection ID, it When an endpoint has requested a non-zero-length connection ID, it
will issue a series of connection IDs over the lifetime of a needs to ensure that the peer has a supply of connection IDs from
connection. The series of connection IDs issued by an endpoint is which to choose for packets sent to the endpoint. These connection
ordered, with the final connection ID selected during the handshake IDs are supplied by the endpoint using the NEW_CONNECTION_ID frame
coming first. Additional connection IDs are provided using the (Section 7.13).
NEW_CONNECTION_ID frame (Section 7.13), each with a specified
sequence number. The series of connection IDs issued SHOULD be
contiguous, but might not appear to be upon receipt due to reordering
or loss.
Each connection ID MUST be used on only one local address. When 6.1.1. Issuing Connection IDs
packets are sent for the first time on a new local address, a new
connection ID MUST be used with a higher sequence number than any
connection ID previously used on any local address. At any time, an
endpoint MAY change to a new connection ID on a local address already
in use.
An endpoint MUST NOT send packets with a connection ID which has a The initial connection ID issued by an endpoint is the Source
lower sequence number than the highest sequence number of any Connection ID during the handshake. The sequence number of the
connection ID ever sent or received on that local address. This initial connection ID is 0. If the preferred_address transport
ensures that when an endpoint migrates to a new path or changes parameter is sent, the sequence number of the supplied connection ID
connection ID on an existing path, the packets will use a new is 1. Subsequent connection IDs are communicated to the peer using
connection ID in both directions. NEW_CONNECTION_ID frames (Section 7.13), and the sequence number on
each newly-issued connection ID MUST increase by 1. The connection
ID randomly selected by the client in the Initial packet and any
connection ID provided by a Reset packet are not assigned sequence
numbers unless a server opts to retain them as its initial connection
ID.
Implementations SHOULD ensure that peers have a connection ID with a When an endpoint issues a connection ID, it MUST accept packets that
matching sequence number available when changing to a new connection carry this connection ID for the duration of the connection or until
ID. An implementation could do this by always supplying a its peer invalidates the connection ID via a RETIRE_CONNECTION_ID
corresponding connection ID to a peer for each connection ID received frame (Section 7.14).
from that peer.
While endpoints select connection IDs as appropriate for their An endpoint SHOULD ensure that its peer has a sufficient number of
implementation, the connection ID MUST NOT include the unprotected available and unused connection IDs. While each endpoint
sequence number. Endpoints need to be able to recover the sequence independently chooses how many connection IDs to issue, endpoints
number associated with each connection ID they generate without SHOULD provide and maintain at least eight connection IDs. The
relying on information available to unaffiliated parties. A endpoint can do this by always supplying a new connection ID when a
connection ID that encodes an unencrypted sequence number could be connection ID is retired by its peer or when the endpoint receives a
used to correlate connection IDs across network paths. packet with a previously unused connection ID. Endpoints that
initiate migration and require non-zero-length connection IDs SHOULD
provide their peers with new connection IDs before migration, or risk
the peer closing the connection.
6.1.2. Consuming and Retiring Connection IDs
An endpoint can change the connection ID it uses for a peer to
another available one at any time during the connection. An endpoint
consumes connection IDs in response to a migrating peer, see
Section 6.11.5 for more.
An endpoint maintains a set of connection IDs received from its peer,
any of which it can use when sending packets. When the endpoint
wishes to remove a connection ID from use, it sends a
RETIRE_CONNECTION_ID frame to its peer, indicating that the peer
might bring a new connection ID into circulation using the
NEW_CONNECTION_ID frame.
An endpoint that retires a connection ID can retain knowledge of that
connection ID for a period of time after sending the
RETIRE_CONNECTION_ID frame, or until that frame is acknowledged.
As discussed in Section 6.11.5, each connection ID MUST be used on
packets sent from only one local address. An endpoint that migrates
away from a local address SHOULD retire all connection IDs used on
that address once it no longer plans to use that address.
6.2. Matching Packets to Connections 6.2. Matching Packets to Connections
Incoming packets are classified on receipt. Packets can either be Incoming packets are classified on receipt. Packets can either be
associated with an existing connection, or - for servers - associated with an existing connection, or - for servers -
potentially create a new connection. potentially create a new connection.
Hosts try to associate a packet with an existing connection. If the Hosts try to associate a packet with an existing connection. If the
packet has a Destination Connection ID corresponding to an existing packet has a Destination Connection ID corresponding to an existing
connection, QUIC processes that packet accordingly. Note that more connection, QUIC processes that packet accordingly. Note that more
than one connection ID can be associated with a connection; see than one connection ID can be associated with a connection; see
Section 6.1. Section 6.1.
If the Destination Connection ID is zero length and the packet If the Destination Connection ID is zero length and the packet
matches the address/port tuple of a connection where the host did not matches the address/port tuple of a connection where the host did not
require connection IDs, QUIC processes the packet as part of that require connection IDs, QUIC processes the packet as part of that
connection. Endpoints MUST drop packets with zero-length Destination connection. Endpoints MUST drop packets with zero-length Destination
Connection ID fields if they do not correspond to a single Connection ID fields if they do not correspond to a single
connection. connection.
Endpoints SHOULD send a Stateless Reset (Section 6.13.4) for any
packets that cannot be attributed to an existing connection.
6.2.1. Client Packet Handling 6.2.1. Client Packet Handling
Valid packets sent to clients always include a Destination Connection Valid packets sent to clients always include a Destination Connection
ID that matches the value the client selects. Clients that choose to ID that matches the value the client selects. Clients that choose to
receive zero-length connection IDs can use the address/port tuple to receive zero-length connection IDs can use the address/port tuple to
identify a connection. Packets that don't match an existing identify a connection. Packets that don't match an existing
connection MAY be discarded. connection are discarded.
Due to packet reordering or loss, clients might receive packets for a Due to packet reordering or loss, clients might receive packets for a
connection that are encrypted with a key it has not yet computed. connection that are encrypted with a key it has not yet computed.
Clients MAY drop these packets, or MAY buffer them in anticipation of Clients MAY drop these packets, or MAY buffer them in anticipation of
later packets that allow it to compute the key. later packets that allow it to compute the key.
If a client receives a packet that has an unsupported version, it If a client receives a packet that has an unsupported version, it
MUST discard that packet. MUST discard that packet.
6.2.2. Server Packet Handling 6.2.2. Server Packet Handling
If a server receives a packet that has an unsupported version and If a server receives a packet that has an unsupported version, but
sufficient length to be an Initial packet for some version supported the packet is sufficiently large to initiate a new connection for any
by the server, it SHOULD send a Version Negotiation packet as version supported by the server, it SHOULD send a Version Negotiation
described in Section 6.3.1. Servers MAY rate control these packets packet as described in Section 6.3.1. Servers MAY rate control these
to avoid storms of Version Negotiation packets. packets to avoid storms of Version Negotiation packets.
The first packet for an unsupported version can use different The first packet for an unsupported version can use different
semantics and encodings for any version-specific field. In semantics and encodings for any version-specific field. In
particular, different packet protection keys might be used for particular, different packet protection keys might be used for
different versions. Servers that do not support a particular version different versions. Servers that do not support a particular version
are unlikely to be able to decrypt the content of the packet. are unlikely to be able to decrypt the payload of the packet.
Servers SHOULD NOT attempt to decode or decrypt a packet from an Servers SHOULD NOT attempt to decode or decrypt a packet from an
unknown version, but instead send a Version Negotiation packet, unknown version, but instead send a Version Negotiation packet,
provided that the packet is sufficiently long. provided that the packet is sufficiently long.
Servers MUST drop other packets that contain unsupported versions. Servers MUST drop other packets that contain unsupported versions.
Packets with a supported version, or no version field, are matched to Packets with a supported version, or no version field, are matched to
a connection as described in Section 6.2. If not matched, the server a connection as described in Section 6.2. If not matched, the server
continues below. continues below.
If the packet is an Initial packet fully conforming with the If the packet is an Initial packet fully conforming with the
specification, the server proceeds with the handshake (Section 6.4). specification, the server proceeds with the handshake (Section 6.4).
This commits the server to the version that the client selected. This commits the server to the version that the client selected.
If a server isn't currently accepting any new connections, it SHOULD If a server isn't currently accepting any new connections, it SHOULD
send a Handshake packet containing a CONNECTION_CLOSE frame with send an Initial packet containing a CONNECTION_CLOSE frame with error
error code SERVER_BUSY. code SERVER_BUSY.
If the packet is a 0-RTT packet, the server MAY buffer a limited If the packet is a 0-RTT packet, the server MAY buffer a limited
number of these packets in anticipation of a late-arriving Initial number of these packets in anticipation of a late-arriving Initial
Packet. Clients are forbidden from sending Handshake packets prior Packet. Clients are forbidden from sending Handshake packets prior
to receiving a server response, so servers SHOULD ignore any such to receiving a server response, so servers SHOULD ignore any such
packets. packets.
Servers MUST drop incoming packets under all other circumstances. Servers MUST drop incoming packets under all other circumstances.
They SHOULD send a Stateless Reset (Section 6.13.4) if a connection
ID is present in the header.
6.3. Version Negotiation 6.3. Version Negotiation
Version negotiation ensures that client and server agree to a QUIC Version negotiation ensures that client and server agree to a QUIC
version that is mutually supported. A server sends a Version version that is mutually supported. A server sends a Version
Negotiation packet in response to each packet that might initiate a Negotiation packet in response to each packet that might initiate a
new connection, see Section 6.2 for details. new connection, see Section 6.2 for details.
The size of the first packet sent by a client will determine whether The size of the first packet sent by a client will determine whether
a server sends a Version Negotiation packet. Clients that support a server sends a Version Negotiation packet. Clients that support
multiple QUIC versions SHOULD pad their Initial packets to reflect multiple QUIC versions SHOULD pad the first packet they send to the
the largest minimum Initial packet size of all their versions. This largest of the minimum packet sizes across all versions they support.
ensures that the server responds if there are any mutually supported This ensures that the server responds if there is a mutually
versions. supported version.
6.3.1. Sending Version Negotiation Packets 6.3.1. Sending Version Negotiation Packets
If the version selected by the client is not acceptable to the If the version selected by the client is not acceptable to the
server, the server responds with a Version Negotiation packet (see server, the server responds with a Version Negotiation packet (see
Section 4.3). This includes a list of versions that the server will Section 4.3). This includes a list of versions that the server will
accept. accept.
This system allows a server to process packets with unsupported This system allows a server to process packets with unsupported
versions without retaining state. Though either the Initial packet versions without retaining state. Though either the Initial packet
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6.3.2. Handling Version Negotiation Packets 6.3.2. Handling Version Negotiation Packets
When the client receives a Version Negotiation packet, it first When the client receives a Version Negotiation packet, it first
checks that the Destination and Source Connection ID fields match the checks that the Destination and Source Connection ID fields match the
Source and Destination Connection ID fields in a packet that the Source and Destination Connection ID fields in a packet that the
client sent. If this check fails, the packet MUST be discarded. client sent. If this check fails, the packet MUST be discarded.
Once the Version Negotiation packet is determined to be valid, the Once the Version Negotiation packet is determined to be valid, the
client then selects an acceptable protocol version from the list client then selects an acceptable protocol version from the list
provided by the server. The client then attempts to create a provided by the server. The client then attempts to create a
connection using that version. Though the contents of the Initial connection using that version. Though the content of the Initial
packet the client sends might not change in response to version packet the client sends might not change in response to version
negotiation, a client MUST increase the packet number it uses on negotiation, a client MUST increase the packet number it uses on
every packet it sends. Packets MUST continue to use long headers and every packet it sends. Packets MUST continue to use long headers and
MUST include the new negotiated protocol version. MUST include the new negotiated protocol version.
The client MUST use the long header format and include its selected The client MUST use the long header format and include its selected
version on all packets until it has 1-RTT keys and it has received a version on all packets until it has 1-RTT keys and it has received a
packet from the server which is not a Version Negotiation packet. packet from the server which is not a Version Negotiation packet.
A client MUST NOT change the version it uses unless it is in response A client MUST NOT change the version it uses unless it is in response
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QUIC provides reliable, ordered delivery of the cryptographic QUIC provides reliable, ordered delivery of the cryptographic
handshake data. QUIC packet protection ensures confidentiality and handshake data. QUIC packet protection ensures confidentiality and
integrity protection that meets the requirements of the cryptographic integrity protection that meets the requirements of the cryptographic
handshake protocol: handshake protocol:
o authenticated key exchange, where o authenticated key exchange, where
* a server is always authenticated, * a server is always authenticated,
* a client is optionally authenticated, * a client is optionally authenticated,
* every connection produces distinct and unrelated keys, * every connection produces distinct and unrelated keys,
* keying material is usable for packet protection for both 0-RTT * keying material is usable for packet protection for both 0-RTT
and 1-RTT packets, and and 1-RTT packets, and
* 1-RTT keys have forward secrecy * 1-RTT keys have forward secrecy
o authenticated values for the transport parameters of the peer (see o authenticated values for the transport parameters of the peer (see
Section 6.6) Section 6.6)
o authenticated confirmation of version negotiation (see o authenticated confirmation of version negotiation (see
Section 6.6.4) Section 6.6.4)
o authenticated negotiation of an application protocol (TLS uses o authenticated negotiation of an application protocol (TLS uses
ALPN [RFC7301] for this purpose) ALPN [RFC7301] for this purpose)
o for the server, the ability to carry data that provides assurance o for the server, the ability to carry data that provides assurance
that the client can receive packets that are addressed with the that the client can receive packets that are addressed with the
transport address that is claimed by the client (see Section 6.9) transport address that is claimed by the client (see Section 6.9)
The initial CRYPTO frame MUST be sent in a single packet. Any second The first CRYPTO frame MUST be sent in a single packet. Any second
attempt that is triggered by address validation MUST also be sent attempt that is triggered by address validation MUST also be sent
within a single packet. This avoids having to reassemble a message within a single packet. This avoids having to reassemble a message
from multiple packets. from multiple packets.
The first client packet of the cryptographic handshake protocol MUST The first client packet of the cryptographic handshake protocol MUST
fit within a 1232 octet QUIC packet payload. This includes overheads fit within a 1232 octet QUIC packet payload. This includes overheads
that reduce the space available to the cryptographic handshake that reduce the space available to the cryptographic handshake
protocol. protocol.
The CRYPTO frame can be sent in different packet number spaces. The CRYPTO frame can be sent in different packet number spaces.
CRYPTO frames in each packet number space carry a separate sequence CRYPTO frames in each packet number space carry a separate sequence
of handshake data starting from an offset of 0. of handshake data starting from an offset of 0.
6.5. Example Handshake Flows 6.5. Example Handshake Flows
Details of how TLS is integrated with QUIC are provided in Details of how TLS is integrated with QUIC are provided in
[QUIC-TLS], but some examples are provided here. [QUIC-TLS], but some examples are provided here.
Figure 8 provides an overview of the 1-RTT handshake. Each line Figure 8 provides an overview of the 1-RTT handshake. Each line
shows a QUIC packet with the packet type and packet number shown shows a QUIC packet with the packet type and packet number shown
first, followed by the contents. So, for instance the first packet first, followed by the frames that are typically contained in those
is of type Initial, with packet number 0, and contains a CRYPTO frame packets. So, for instance the first packet is of type Initial, with
carrying the ClientHello. packet number 0, and contains a CRYPTO frame carrying the
ClientHello.
Note that multiple QUIC packets - even of different encryption levels Note that multiple QUIC packets - even of different encryption levels
- may be coalesced into a single UDP datagram (see Section 4.9), and - may be coalesced into a single UDP datagram (see Section 4.9), and
so this handshake may consist of as few as 4 UDP datagrams, or any so this handshake may consist of as few as 4 UDP datagrams, or any
number more. For instance, the server's first flight contains number more. For instance, the server's first flight contains
packets from the Initial encryption level (obfuscation), the packets from the Initial encryption level (obfuscation), the
Handshake level, and "0.5-RTT data" from the server at the 1-RTT Handshake level, and "0.5-RTT data" from the server at the 1-RTT
encryption level. encryption level.
Client Server Client Server
skipping to change at page 36, line 49 skipping to change at page 38, line 45
<- 1-RTT[0]: STREAM[1, "..."] ACK[0] <- 1-RTT[0]: STREAM[1, "..."] ACK[0]
Initial[1]: ACK[0] Initial[1]: ACK[0]
0-RTT[1]: CRYPTO[EOED] 0-RTT[1]: CRYPTO[EOED]
Handshake[0]: CRYPTO[FIN], ACK[0] Handshake[0]: CRYPTO[FIN], ACK[0]
1-RTT[2]: STREAM[0, "..."] ACK[0] -> 1-RTT[2]: STREAM[0, "..."] ACK[0] ->
1-RTT[1]: STREAM[55, "..."], ACK[1,2] 1-RTT[1]: STREAM[55, "..."], ACK[1,2]
<- Handshake[1]: ACK[0] <- Handshake[1]: ACK[0]
Figure 9: Example 1-RTT Handshake Figure 9: Example 0-RTT Handshake
6.6. Transport Parameters 6.6. Transport Parameters
During connection establishment, both endpoints make authenticated During connection establishment, both endpoints make authenticated
declarations of their transport parameters. These declarations are declarations of their transport parameters. These declarations are
made unilaterally by each endpoint. Endpoints are required to comply made unilaterally by each endpoint. Endpoints are required to comply
with the restrictions implied by these parameters; the description of with the restrictions implied by these parameters; the description of
each parameter includes rules for its handling. each parameter includes rules for its handling.
The format of the transport parameters is the TransportParameters The format of the transport parameters is the TransportParameters
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initial_max_bidi_streams(2), initial_max_bidi_streams(2),
idle_timeout(3), idle_timeout(3),
preferred_address(4), preferred_address(4),
max_packet_size(5), max_packet_size(5),
stateless_reset_token(6), stateless_reset_token(6),
ack_delay_exponent(7), ack_delay_exponent(7),
initial_max_uni_streams(8), initial_max_uni_streams(8),
disable_migration(9), disable_migration(9),
initial_max_stream_data_bidi_remote(10), initial_max_stream_data_bidi_remote(10),
initial_max_stream_data_uni(11), initial_max_stream_data_uni(11),
max_ack_delay(12),
original_connection_id(13),
(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) {
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properly complete. properly complete.
Definitions for each of the defined transport parameters are included Definitions for each of the defined transport parameters are included
in Section 6.6.1. Any given parameter MUST appear at most once in a in Section 6.6.1. Any given parameter MUST appear at most once in a
given transport parameters extension. An endpoint MUST treat receipt given transport parameters extension. An endpoint MUST treat receipt
of duplicate transport parameters as a connection error of type of duplicate transport parameters as a connection error of type
TRANSPORT_PARAMETER_ERROR. TRANSPORT_PARAMETER_ERROR.
6.6.1. Transport Parameter Definitions 6.6.1. Transport Parameter Definitions
An endpoint MUST include the following parameters in its encoded
TransportParameters:
idle_timeout (0x0003): The idle timeout is a value in seconds that
is encoded as an unsigned 16-bit integer. The maximum value is
600 seconds (10 minutes).
An endpoint MAY use the following transport parameters: An endpoint MAY use the following transport parameters:
initial_max_data (0x0001): The initial maximum data parameter initial_max_data (0x0001): The initial maximum data parameter
contains the initial value for the maximum amount of data that can contains the initial value for the maximum amount of data that can
be sent on the connection. This parameter is encoded as an be sent on the connection. This parameter is encoded as an
unsigned 32-bit integer in units of octets. This is equivalent to unsigned 32-bit integer in units of octets. This is equivalent to
sending a MAX_DATA (Section 7.6) for the connection immediately sending a MAX_DATA (Section 7.6) for the connection immediately
after completing the handshake. If the transport parameter is after completing the handshake. If the transport parameter is
absent, the connection starts with a flow control limit of 0. absent, the connection starts with a flow control limit of 0.
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unidirectional streams the peer may initiate, encoded as an unidirectional streams the peer may initiate, encoded as an
unsigned 16-bit integer. If this parameter is absent or zero, unsigned 16-bit integer. If this parameter is absent or zero,
unidirectional streams cannot be created until a MAX_STREAM_ID unidirectional streams cannot be created until a MAX_STREAM_ID
frame is sent. Setting this parameter is equivalent to sending a frame is sent. Setting this parameter is equivalent to sending a
MAX_STREAM_ID (Section 7.8) immediately after completing the MAX_STREAM_ID (Section 7.8) immediately after completing the
handshake containing the corresponding Stream ID. For example, a handshake containing the corresponding Stream ID. For example, a
value of 0x05 would be equivalent to receiving a MAX_STREAM_ID value of 0x05 would be equivalent to receiving a MAX_STREAM_ID
containing 18 when received by a client or 19 when received by a containing 18 when received by a client or 19 when received by a
server. server.
idle_timeout (0x0003): The idle timeout is a value in seconds that
is encoded as an unsigned 16-bit integer. If this parameter is
absent or zero then the idle timeout is disabled.
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 4.8). protected packets (Section 4.8).
ack_delay_exponent (0x0007): An 8-bit unsigned integer value ack_delay_exponent (0x0007): An 8-bit unsigned integer value
indicating an exponent used to decode the ACK Delay field in the indicating an exponent used to decode the ACK Delay field in the
ACK frame, see Section 7.15. If this value is absent, a default ACK frame, see Section 7.16. If this value is absent, a default
value of 3 is assumed (indicating a multiplier of 8). The default value of 3 is assumed (indicating a multiplier of 8). The default
value is also used for ACK frames that are sent in Initial and value is also used for ACK frames that are sent in Initial and
Handshake packets. Values above 20 are invalid. Handshake packets. Values above 20 are invalid.
disable_migration (0x0009): The endpoint does not support connection disable_migration (0x0009): The endpoint does not support connection
migration (Section 6.11). Peers MUST NOT send any packets, migration (Section 6.11). Peers MUST NOT send any packets,
including probing packets (Section 6.11.1), from a local address including probing packets (Section 6.11.1), from a local address
other than that used to perform the handshake. This parameter is other than that used to perform the handshake. This parameter is
a zero-length value. a zero-length value.
max_ack_delay (0x000c): An 8 bit unsigned integer value indicating
the maximum amount of time in milliseconds by which it will delay
sending of acknowledgments. If this value is absent, a default of
25 milliseconds is assumed.
Either peer MAY advertise an initial value for the flow control on Either peer MAY advertise an initial value for the flow control on
each type of stream on which they might receive data. Each of the each type of stream on which they might receive data. Each of the
following transport parameters is encoded as an unsigned 32-bit following transport parameters is encoded as an unsigned 32-bit
integer in units of octets: integer in units of octets:
initial_max_stream_data_bidi_local (0x0000): The initial stream initial_max_stream_data_bidi_local (0x0000): The initial stream
maximum data for bidirectional, locally-initiated streams maximum data for bidirectional, locally-initiated streams
parameter contains the initial flow control limit for newly parameter contains the initial flow control limit for newly
created bidirectional streams opened by the endpoint that sets the created bidirectional streams opened by the endpoint that sets the
transport parameter. In client transport parameters, this applies transport parameter. In client transport parameters, this applies
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transport parameters, this applies to streams with an identifier transport parameters, this applies to streams with an identifier
ending in 0x3; in server transport parameters, this applies to ending in 0x3; in server transport parameters, this applies to
streams ending in 0x2. streams ending in 0x2.
If present, transport parameters that set initial stream flow control If present, transport parameters that set initial stream flow control
limits are equivalent to sending a MAX_STREAM_DATA frame limits are equivalent to sending a MAX_STREAM_DATA frame
(Section 7.7) on every stream of the corresponding type immediately (Section 7.7) on every stream of the corresponding type immediately
after opening. If the transport parameter is absent, streams of that after opening. If the transport parameter is absent, streams of that
type start with a flow control limit of 0. type start with a flow control limit of 0.
A server MUST include the original_connection_id transport parameter
if it sent a Retry packet:
original_connection_id (0x000d): The value of the Destination
Connection ID field from the first Initial packet sent by the
client. This transport parameter is only sent by the server.
A server MAY include the following transport parameters: A server MAY include the following transport parameters:
stateless_reset_token (0x0006): The Stateless Reset Token is used in stateless_reset_token (0x0006): The Stateless Reset Token is used in
verifying a stateless reset, see Section 6.13.4. This parameter verifying a stateless reset, see Section 6.13.4. This parameter
is a sequence of 16 octets. is a sequence of 16 octets.
preferred_address (0x0004): The server's Preferred Address is used preferred_address (0x0004): The server's Preferred Address is used
to effect a change in server address at the end of the handshake, to effect a change in server address at the end of the handshake,
as described in Section 6.12. as described in Section 6.12.
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versions it supports. The version field in the QUIC packet header is versions it supports. The version field in the QUIC packet header is
authenticated using transport parameters. The position and the authenticated using transport parameters. The position and the
format of the version fields in transport parameters MUST either be format of the version fields in transport parameters MUST either be
identical across different QUIC versions, or be unambiguously identical across different QUIC versions, or be unambiguously
different to ensure no confusion about their interpretation. One way different to ensure no confusion about their interpretation. One way
that a new format could be introduced is to define a TLS extension that a new format could be introduced is to define a TLS extension
with a different codepoint. with a different codepoint.
6.7. Stateless Retries 6.7. Stateless Retries
A server can process an initial cryptographic handshake messages from A server can process an Initial packet from a client without
a client without committing any state. This allows a server to committing any state. This allows a server to perform address
perform address validation (Section 6.9), or to defer connection validation (Section 6.9), or to defer connection establishment costs.
establishment costs.
A server that generates a response to an Initial packet without A server that generates a response to an Initial packet without
retaining connection state MUST use the Retry packet (Section 4.4). retaining connection state MUST use the Retry packet (Section 4.4).
This packet causes a client to restart the connection attempt and This packet causes a client to restart the connection attempt and
includes the token in the new Initial packet (Section 4.6) to prove includes the token in the new Initial packet (Section 4.6) to prove
source address ownership. source address ownership.
6.8. Using Explicit Congestion Notification 6.8. Using Explicit Congestion Notification
QUIC endpoints use Explicit Congestion Notification (ECN) [RFC3168] QUIC endpoints use Explicit Congestion Notification (ECN) [RFC3168]
to detect and respond to network congestion. ECN allows a network to detect and respond to network congestion. ECN allows a network
node to indicate congestion in the network by setting a codepoint in node to indicate congestion in the network by setting a codepoint in
the IP header of a packet instead of dropping it. Endpoints react to the IP header of a packet instead of dropping it. Endpoints react to
congestion by reducing their sending rate in response, as described congestion by reducing their sending rate in response, as described
in [QUIC-RECOVERY]. in [QUIC-RECOVERY].
To use ECN, QUIC endpoints first determine whether a path and peer To use ECN, QUIC endpoints first determine whether a path supports
support ECN marking. Verifying the path occurs at the beginning of a ECN marking and the peer is able to access the ECN codepoint in the
connection and when the connection migrates to a new path (see IP header. A network path does not support ECN if ECN marked packets
Section 6.11). get dropped or ECN markings are rewritten on the path. An endpoint
verifies the path, both during connection establishment and when
migrating to a new path (see Section 6.11).
Each endpoint independently verifies and enables ECN for the path Each endpoint independently verifies and enables use of ECN by
from it to the peer. setting the IP header ECN codepoint to ECN Capable Transport (ECT)
for the path from it to the other peer. Even if ECN is not used on
the path to the peer, the endpoint MUST provide feedback about ECN
markings received (if accessible).
To verify that both a path and the peer support ECN, an endpoint MUST To verify both that a path supports ECN and the peer can provide ECN
set one of the ECN Capable Transport (ECT) codepoints - ECT(0) or feedback, an endpoint MUST set the ECT(0) codepoint in the IP header
ECT(1) - in the IP header [RFC8311] of all outgoing packets. of all outgoing packets [RFC8311].
If an ECT codepoint set in the IP header is not corrupted by a If an ECT codepoint set in the IP header is not corrupted by a
network device, then a received packet contains either the codepoint network device, then a received packet contains either the codepoint
sent by the peer or the Congestion Experienced (CE) codepoint set by sent by the peer or the Congestion Experienced (CE) codepoint set by
a network device that is experiencing congestion. a network device that is experiencing congestion.
On receiving a packet with an ECT or CE codepoint, an endpoint that On receiving a packet with an ECT or CE codepoint, an endpoint that
supports ECN increases the corresponding ECT(0), ECT(1), or CE count, can access the IP ECN codepoints increases the corresponding ECT(0),
and includes these counters in subsequent (see Section 8.1) ACK_ECN ECT(1), or CE count, and includes these counters in subsequent (see
frames (see Section 7.16). Section 8.1) ACK frames (see Section 7.16).
A packet detected by a receiver as a duplicate does not affect the A packet detected by a receiver as a duplicate does not affect the
receiver's local ECN codepoint counts; see (Section 12.7) for receiver's local ECN codepoint counts; see (Section 12.7) for
relevant security concerns. relevant security concerns.
If an endpoint receives a packet without an ECT or CE codepoint, it If an endpoint receives a packet without an ECT or CE codepoint, it
responds per Section 8.1 with an ACK frame. responds per Section 8.1 with an ACK frame.
If an endpoint does not support ECN or does not have access to If an endpoint does not have access to received ECN codepoints, it
received ECN codepoints, it acknowledges received packets per acknowledges received packets per Section 8.1 with an ACK frame.
Section 8.1 with an ACK frame.
If a packet sent with an ECT codepoint is newly acknowledged by the If a packet sent with an ECT codepoint is newly acknowledged by the
peer in an ACK frame, the endpoint stops setting ECT codepoints in peer in an ACK frame, the endpoint stops setting ECT codepoints in
subsequent packets, with the expectation that either the network or subsequent packets, with the expectation that either the network or
the peer no longer supports ECN. the peer no longer supports ECN.
To protect the connection from arbitrary corruption of ECN codepoints To protect the connection from arbitrary corruption of ECN codepoints
by the network, an endpoint verifies the following when an ACK_ECN by the network, an endpoint verifies the following when an ACK frame
frame is received: is received:
o The increase in ECT(0) and ECT(1) counters MUST be at least the o The increase in ECT(0) and ECT(1) counters MUST be at least the
number of packets newly acknowledged that were sent with the number of packets newly acknowledged that were sent with the
corresponding codepoint. corresponding codepoint.
o The total increase in ECT(0), ECT(1), and CE counters reported in o The total increase in ECT(0), ECT(1), and CE counters reported in
the ACK_ECN frame MUST be at least the total number of packets the ACK frame MUST be at least the total number of packets newly
newly acknowledged in this ACK_ECN frame. acknowledged in this ACK frame.
An endpoint could miss acknowledgements for a packet when ACK frames An endpoint could miss acknowledgements for a packet when ACK frames
are lost. It is therefore possible for the total increase in ECT(0), are lost. It is therefore possible for the total increase in ECT(0),
ECT(1), and CE counters to be greater than the number of packets ECT(1), and CE counters to be greater than the number of packets
acknowledged in an ACK frame. When this happens, the local reference acknowledged in an ACK frame. When this happens, the local reference
counts MUST be increased to match the counters in the ACK frame. counts MUST be increased to match the counters in the ACK frame.
Upon successful verification, an endpoint continues to set ECT Upon successful verification, an endpoint continues to set ECT
codepoints in subsequent packets with the expectation that the path codepoints in subsequent packets with the expectation that the path
is ECN-capable. is ECN-capable.
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or other peer is able to receive packets without first having sent a or other peer is able to receive packets without first having sent a
packet on that path. Effective NAT traversal needs additional packet on that path. Effective NAT traversal needs additional
synchronization mechanisms that are not provided here. synchronization mechanisms that are not provided here.
An endpoint MAY bundle PATH_CHALLENGE and PATH_RESPONSE frames that An endpoint MAY bundle PATH_CHALLENGE and PATH_RESPONSE frames that
are used for path validation with other frames. For instance, an are used for path validation with other frames. For instance, an
endpoint may pad a packet carrying a PATH_CHALLENGE for PMTU endpoint may pad a packet carrying a PATH_CHALLENGE for PMTU
discovery, or an endpoint may bundle a PATH_RESPONSE with its own discovery, or an endpoint may bundle a PATH_RESPONSE with its own
PATH_CHALLENGE. PATH_CHALLENGE.
When probing a new path, an endpoint might want to ensure that its
peer has an unused connection ID available for responses. The
endpoint can send NEW_CONNECTION_ID and PATH_CHALLENGE frames in the
same packet. This ensures that an unused connection ID will be
available to the peer when sending a response.
6.10.1. Initiation 6.10.1. Initiation
To initiate path validation, an endpoint sends a PATH_CHALLENGE frame To initiate path validation, an endpoint sends a PATH_CHALLENGE frame
containing a random payload on the path to be validated. containing a random payload on the path to be validated.
An endpoint MAY send additional PATH_CHALLENGE frames to handle An endpoint MAY send additional PATH_CHALLENGE frames to handle
packet loss. An endpoint SHOULD NOT send a PATH_CHALLENGE more packet loss. An endpoint SHOULD NOT send a PATH_CHALLENGE more
frequently than it would an Initial packet, ensuring that connection frequently than it would an Initial packet, ensuring that connection
migration is no more load on a new path than establishing a new migration is no more load on a new path than establishing a new
connection. connection.
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available or close the connection. available or close the connection.
A path validation might be abandoned for other reasons besides A path validation might be abandoned for other reasons besides
failure. Primarily, this happens if a connection migration to a new failure. Primarily, this happens if a connection migration to a new
path is initiated while a path validation on the old path is in path is initiated while a path validation on the old path is in
progress. progress.
6.11. Connection Migration 6.11. Connection Migration
QUIC allows connections to survive changes to endpoint addresses QUIC allows connections to survive changes to endpoint addresses
(that is, IP address and/or port), such as those caused by a endpoint (that is, IP address and/or port), such as those caused by an
migrating to a new network. This section describes the process by endpoint migrating to a new network. This section describes the
which an endpoint migrates to a new address. process by which an endpoint migrates to a new address.
An endpoint MUST NOT initiate connection migration before the An endpoint MUST NOT initiate connection migration before the
handshake is finished and the endpoint has 1-RTT keys. The design of handshake is finished and the endpoint has 1-RTT keys. The design of
QUIC relies on endpoints retaining a stable address for the duration QUIC relies on endpoints retaining a stable address for the duration
of the handshake. of the handshake.
An endpoint also MUST NOT initiate connection migration if the peer An endpoint also MUST NOT initiate connection migration if the peer
sent the "disable_migration" transport parameter during the sent the "disable_migration" transport parameter during the
handshake. An endpoint which has sent this transport parameter, but handshake. An endpoint which has sent this transport parameter, but
detects that a peer has nonetheless migrated to a different network detects that a peer has nonetheless migrated to a different network
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Not all changes of peer address are intentional migrations. The peer Not all changes of peer address are intentional migrations. The peer
could experience NAT rebinding: a change of address due to a could experience NAT rebinding: a change of address due to a
middlebox, usually a NAT, allocating a new outgoing port or even a middlebox, usually a NAT, allocating a new outgoing port or even a
new outgoing IP address for a flow. Endpoints SHOULD perform path new outgoing IP address for a flow. Endpoints SHOULD perform path
validation (Section 6.10) if a NAT rebinding does not cause the validation (Section 6.10) if a NAT rebinding does not cause the
connection to fail. connection to fail.
This document limits migration of connections to new client This document limits migration of connections to new client
addresses, except as described in Section 6.12. Clients are addresses, except as described in Section 6.12. Clients are
responsible for initiating all migrations. Servers do not send non- responsible for initiating all migrations. Servers do not send non-
probing packets (see Section 6.11.1) toward a client address until it probing packets (see Section 6.11.1) toward a client address until
sees a non-probing packet from that address. If a client receives they see a non-probing packet from that address. If a client
packets from an unknown server address, the client MAY discard these receives packets from an unknown server address, the client MAY
packets. discard these packets.
6.11.1. Probing a New Path 6.11.1. Probing a New Path
An endpoint MAY probe for peer reachability from a new local address An endpoint MAY probe for peer reachability from a new local address
using path validation Section 6.10 prior to migrating the connection using path validation Section 6.10 prior to migrating the connection
to the new local address. Failure of path validation simply means to the new local address. Failure of path validation simply means
that the new path is not usable for this connection. Failure to that the new path is not usable for this connection. Failure to
validate a path does not cause the connection to end unless there are validate a path does not cause the connection to end unless there are
no valid alternative paths available. no valid alternative paths available.
An endpoint uses a new connection ID for probes sent from a new local An endpoint uses a new connection ID for probes sent from a new local
address, see Section 6.11.5 for further discussion. address, see Section 6.11.5 for further discussion. An endpoint that
uses a new local address needs to ensure that at least one new
connection ID is available at the peer. That can be achieved by
including a NEW_CONNECTION_ID frame in the probe.
Receiving a PATH_CHALLENGE frame from a peer indicates that the peer Receiving a PATH_CHALLENGE frame from a peer indicates that the peer
is probing for reachability on a path. An endpoint sends a is probing for reachability on a path. An endpoint sends a
PATH_RESPONSE in response as per Section 6.10. PATH_RESPONSE in response as per Section 6.10.
PATH_CHALLENGE, PATH_RESPONSE, and PADDING frames are "probing PATH_CHALLENGE, PATH_RESPONSE, NEW_CONNECTION_ID, and PADDING frames
frames", and all other frames are "non-probing frames". A packet are "probing frames", and all other frames are "non-probing frames".
containing only probing frames is a "probing packet", and a packet A packet containing only probing frames is a "probing packet", and a
containing any other frame is a "non-probing packet". packet containing any other frame is a "non-probing packet".
6.11.2. Initiating Connection Migration 6.11.2. Initiating Connection Migration
A endpoint can migrate a connection to a new local address by sending An endpoint can migrate a connection to a new local address by
packets containing frames other than probing frames from that sending packets containing frames other than probing frames from that
address. address.
Each endpoint validates its peer's address during connection Each endpoint validates its peer's address during connection
establishment. Therefore, a migrating endpoint can send to its peer establishment. Therefore, a migrating endpoint can send to its peer
knowing that the peer is willing to receive at the peer's current knowing that the peer is willing to receive at the peer's current
address. Thus an endpoint can migrate to a new local address without address. Thus an endpoint can migrate to a new local address without
first validating the peer's address. first validating the peer's address.
When migrating, the new path might not support the endpoint's current When migrating, the new path might not support the endpoint's current
sending rate. Therefore, the endpoint resets its congestion sending rate. Therefore, the endpoint resets its congestion
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PATH_RESPONSE is received, the endpoint might send a new PATH_RESPONSE is received, the endpoint might send a new
PATH_CHALLENGE, and restart the timer for a longer period of time. PATH_CHALLENGE, and restart the timer for a longer period of time.
6.11.5. Privacy Implications of Connection Migration 6.11.5. Privacy Implications of Connection Migration
Using a stable connection ID on multiple network paths allows a Using a stable connection ID on multiple network paths allows a
passive observer to correlate activity between those paths. An passive observer to correlate activity between those paths. An
endpoint that moves between networks might not wish to have their endpoint that moves between networks might not wish to have their
activity correlated by any entity other than their peer, so different activity correlated by any entity other than their peer, so different
connection IDs are used when sending from different local addresses, connection IDs are used when sending from different local addresses,
as discussed in Section 6.1. as discussed in Section 6.1. For this to be effective endpoints need
to ensure that connections IDs they provide cannot be linked by any
other entity.
This eliminates the use of the connection ID for linking activity This eliminates the use of the connection ID for linking activity
from the same connection on different networks. Protection of packet from the same connection on different networks. Protection of packet
numbers ensures that packet numbers cannot be used to correlate numbers ensures that packet numbers cannot be used to correlate
activity. This does not prevent other properties of packets, such as activity. This does not prevent other properties of packets, such as
timing and size, from being used to correlate activity. timing and size, from being used to correlate activity.
Clients MAY move to a new connection ID at any time based on Clients MAY move to a new connection ID at any time based on
implementation-specific concerns. For example, after a period of implementation-specific concerns. For example, after a period of
network inactivity NAT rebinding might occur when the client begins network inactivity NAT rebinding might occur when the client begins
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A client might wish to reduce linkability by employing a new A client might wish to reduce linkability by employing a new
connection ID and source UDP port when sending traffic after a period connection ID and source UDP port when sending traffic after a period
of inactivity. Changing the UDP port from which it sends packets at of inactivity. Changing the UDP port from which it sends packets at
the same time might cause the packet to appear as a connection the same time might cause the packet to appear as a connection
migration. This ensures that the mechanisms that support migration migration. This ensures that the mechanisms that support migration
are exercised even for clients that don't experience NAT rebindings are exercised even for clients that don't experience NAT rebindings
or genuine migrations. Changing port number can cause a peer to or genuine migrations. Changing port number can cause a peer to
reset its congestion state (see Section 6.11.4), so the port SHOULD reset its congestion state (see Section 6.11.4), so the port SHOULD
only be changed infrequently. only be changed infrequently.
Endpoints that use connection IDs with length greater than zero could
have their activity correlated if their peers keep using the same
destination connection ID after migration. Endpoints that receive
packets with a previously unused Destination Connection ID SHOULD
change to sending packets with a connection ID that has not been used
on any other network path. The goal here is to ensure that packets
sent on different paths cannot be correlated. To fulfill this
privacy requirement, endpoints that initiate migration and use
connection IDs with length greater than zero SHOULD provide their
peers with new connection IDs before migration.
Caution: If both endpoints change connection ID in response to
seeing a change in connection ID from their peer, then this can
trigger an infinite sequence of changes.
6.12. Server's Preferred Address 6.12. Server's Preferred Address
QUIC allows servers to accept connections on one IP address and QUIC allows servers to accept connections on one IP address and
attempt to transfer these connections to a more preferred address attempt to transfer these connections to a more preferred address
shortly after the handshake. This is particularly useful when shortly after the handshake. This is particularly useful when
clients initially connect to an address shared by multiple servers clients initially connect to an address shared by multiple servers
but would prefer to use a unicast address to ensure connection but would prefer to use a unicast address to ensure connection
stability. This section describes the protocol for migrating a stability. This section describes the protocol for migrating a
connection to a preferred server address. connection to a preferred server address.
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An endpoint could receive packets from a new source address, An endpoint could receive packets from a new source address,
indicating a client connection migration (Section 6.11), while in the indicating a client connection migration (Section 6.11), while in the
closing period. An endpoint in the closing state MUST strictly limit closing period. An endpoint in the closing state MUST strictly limit
the number of packets it sends to this new address until the address the number of packets it sends to this new address until the address
is validated (see Section 6.10). A server in the closing state MAY is validated (see Section 6.10). A server in the closing state MAY
instead choose to discard packets received from a new source address. instead choose to discard packets received from a new source address.
6.13.2. Idle Timeout 6.13.2. Idle Timeout
A connection that remains idle for longer than the advertised idle If the idle timeout is enabled, a connection that remains idle for
timeout (see Section 6.6.1) is closed. A connection enters the longer than the advertised idle timeout (see Section 6.6.1) is
draining state when the idle timeout expires. closed. A connection enters the draining state when the idle timeout
expires.
Each endpoint advertises their own idle timeout to their peer. The Each endpoint advertises their own idle timeout to their peer. The
idle timeout starts from the last packet received. In order to idle timeout starts from the last packet received. In order to
ensure that initiating new activity postpones an idle timeout, an ensure that initiating new activity postpones an idle timeout, an
endpoint restarts this timer when sending a packet. An endpoint does endpoint restarts this timer when sending a packet. An endpoint does
not postpone the idle timeout if another packet has been sent not postpone the idle timeout if another packet has been sent
containing frames other than ACK or PADDING, and that other packet containing frames other than ACK or PADDING, and that other packet
has not been acknowledged or declared lost. Packets that contain has not been acknowledged or declared lost. Packets that contain
only ACK or PADDING frames are not acknowledged until an endpoint has only ACK or PADDING frames are not acknowledged until an endpoint has
other frames to send, so they could prevent the timeout from being other frames to send, so they could prevent the timeout from being
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endpoint that is unable to properly continue the connection. An endpoint that is unable to properly continue the connection. An
endpoint that wishes to communicate a fatal connection error MUST use endpoint that wishes to communicate a fatal connection error MUST use
a closing frame if it has sufficient state to do so. a closing frame if it has sufficient state to do so.
To support this process, a token is sent by endpoints. The token is To support this process, a token is sent by endpoints. The token is
carried in the NEW_CONNECTION_ID frame sent by either peer, and carried in the NEW_CONNECTION_ID frame sent by either peer, and
servers can specify the stateless_reset_token transport parameter servers can specify the stateless_reset_token transport parameter
during the handshake (clients cannot because their transport during the handshake (clients cannot because their transport
parameters don't have confidentiality protection). This value is parameters don't have confidentiality protection). This value is
protected by encryption, so only client and server know this value. protected by encryption, so only client and server know this value.
Tokens sent via NEW_CONNECTION_ID frames are invalidated when their
associated connection ID is retired via a RETIRE_CONNECTION_ID frame
(Section 7.14).
An endpoint that receives packets that it cannot process sends a An endpoint that receives packets that it cannot process sends a
packet in the following layout: packet in the following layout:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|0|K|1|1|0|0|0|0| |0|K|1|1|0|0|0|0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Random Octets (160..) ... | Random Octets (160..) ...
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An endpoint MAY send a stateless reset in response to a packet with a An endpoint MAY send a stateless reset in response to a packet with a
long header. This would not be effective if the stateless reset long header. This would not be effective if the stateless reset
token was not yet available to a peer. In this QUIC version, packets token was not yet available to a peer. In this QUIC version, packets
with a long header are only used during connection establishment. with a long header are only used during connection establishment.
Because the stateless reset token is not available until connection Because the stateless reset token is not available until connection
establishment is complete or near completion, ignoring an unknown establishment is complete or near completion, ignoring an unknown
packet with a long header might be more effective. packet with a long header might be more effective.
An endpoint cannot determine the Source Connection ID from a packet An endpoint cannot determine the Source Connection ID from a packet
with a short header, therefore it cannot set the Destination with a short header, therefore it cannot set the Destination
Connection ID in the stateless reset packet. The destination Connection ID in the stateless reset packet. The Destination
connection ID will therefore differ from the value used in previous Connection ID will therefore differ from the value used in previous
packets. A random Destination Connection ID makes the connection ID packets. A random Destination Connection ID makes the connection ID
appear to be the result of moving to a new connection ID that was appear to be the result of moving to a new connection ID that was
provided using a NEW_CONNECTION_ID frame (Section 7.13). provided using a NEW_CONNECTION_ID frame (Section 7.13).
Using a randomized connection ID results in two problems: Using a randomized connection ID results in two problems:
o The packet might not reach the peer. If the Destination o The packet might not reach the peer. If the Destination
Connection ID is critical for routing toward the peer, then this Connection ID is critical for routing toward the peer, then this
packet could be incorrectly routed. This might also trigger packet could be incorrectly routed. This might also trigger
another Stateless Reset in response, see Section 6.13.4.3. A another Stateless Reset in response, see Section 6.13.4.3. A
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these values are identical, the endpoint MUST enter the draining these values are identical, the endpoint MUST enter the draining
period and not send any further packets on this connection. If the period and not send any further packets on this connection. If the
comparison fails, the packet can be discarded. comparison fails, the packet can be discarded.
6.13.4.2. Calculating a Stateless Reset Token 6.13.4.2. Calculating a Stateless Reset Token
The stateless reset token MUST be difficult to guess. In order to The stateless reset token MUST be difficult to guess. In order to
create a Stateless Reset Token, an endpoint could randomly generate create a Stateless Reset Token, an endpoint could randomly generate
[RFC4086] a secret for every connection that it creates. However, [RFC4086] a secret for every connection that it creates. However,
this presents a coordination problem when there are multiple this presents a coordination problem when there are multiple
instances in a cluster or a storage problem for a endpoint that might instances in a cluster or a storage problem for an endpoint that
lose state. Stateless reset specifically exists to handle the case might lose state. Stateless reset specifically exists to handle the
where state is lost, so this approach is suboptimal. case where state is lost, so this approach is suboptimal.
A single static key can be used across all connections to the same A single static key can be used across all connections to the same
endpoint by generating the proof using a second iteration of a endpoint by generating the proof using a second iteration of a
preimage-resistant function that takes a static key and the preimage-resistant function that takes a static key and the
connection ID chosen by the endpoint (see Section 6.1) as input. An connection ID chosen by the endpoint (see Section 6.1) as input. An
endpoint could use HMAC [RFC2104] (for example, HMAC(static_key, endpoint could use HMAC [RFC2104] (for example, HMAC(static_key,
connection_id)) or HKDF [RFC5869] (for example, using the static key connection_id)) or HKDF [RFC5869] (for example, using the static key
as input keying material, with the connection ID as salt). The as input keying material, with the connection ID as salt). The
output of this function is truncated to 16 octets to produce the output of this function is truncated to 16 octets to produce the
Stateless Reset Token for that connection. Stateless Reset Token for that connection.
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protection. protection.
6.13.4.3. Looping 6.13.4.3. Looping
The design of a Stateless Reset is such that it is indistinguishable The design of a Stateless Reset is such that it is indistinguishable
from a valid packet. This means that a Stateless Reset might trigger from a valid packet. This means that a Stateless Reset might trigger
the sending of a Stateless Reset in response, which could lead to the sending of a Stateless Reset in response, which could lead to
infinite exchanges. infinite exchanges.
An endpoint MUST ensure that every Stateless Reset that it sends is An endpoint MUST ensure that every Stateless Reset that it sends is
smaller than the packet triggered it, unless it maintains state smaller than the packet which triggered it, unless it maintains state
sufficient to prevent looping. In the event of a loop, this results sufficient to prevent looping. In the event of a loop, this results
in packets eventually being too small to trigger a response. in packets eventually being too small to trigger a response.
An endpoint can remember the number of Stateless Reset packets that An endpoint can remember the number of Stateless Reset packets that
it has sent and stop generating new Stateless Reset packets once a it has sent and stop generating new Stateless Reset packets once a
limit is reached. Using separate limits for different remote limit is reached. Using separate limits for different remote
addresses will ensure that Stateless Reset packets can be used to addresses will ensure that Stateless Reset packets can be used to
close connections when other peers or connections have exhausted close connections when other peers or connections have exhausted
limits. limits.
Reducing the size of a Stateless Reset below the recommended minimum Reducing the size of a Stateless Reset below the recommended minimum
size of 37 octets could mean that the packet could reveal to an size of 37 octets could mean that the packet could reveal to an
observer that it is a Stateless Reset. Conversely, refusing to send observer that it is a Stateless Reset. Conversely, refusing to send
a Stateless Reset in response to a small packet might result in a Stateless Reset in response to a small packet might result in
Stateless Reset not being useful in detecting cases of broken Stateless Reset not being useful in detecting cases of broken
connections where only very small packets are sent; such failures connections where only very small packets are sent; such failures
might only be detected by other means, such as timers. might only be detected by other means, such as timers.
An endpoint can increase the odds that a packet will trigger a
Stateless Reset if it cannot be processed by padding it to at least
38 octets.
7. Frame Types and Formats 7. Frame Types and Formats
As described in Section 5, packets contain one or more frames. This As described in Section 5, packets contain one or more frames. This
section describes the format and semantics of the core QUIC frame section describes the format and semantics of the core QUIC frame
types. types.
7.1. Variable-Length Integer Encoding 7.1. Variable-Length Integer Encoding
QUIC frames commonly use a variable-length encoding for non-negative QUIC frames commonly use a variable-length encoding for non-negative
integer values. This encoding ensures that smaller integer values integer values. This encoding ensures that smaller integer values
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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) | | Error Code (16) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reason Phrase Length (i) ... | Reason Phrase Length (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reason Phrase (*) ... | Reason Phrase (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields of a APPLICATION_CLOSE frame are as follows: The fields of an APPLICATION_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. APPLICATION_CLOSE uses codes from the closing this connection. APPLICATION_CLOSE uses codes from the
application protocol error code space, see Section 11.4. application protocol error code space, see Section 11.4.
Reason Phrase Length: This field is identical in format and Reason Phrase Length: This field is identical in format and
semantics to the Reason Phrase Length field from CONNECTION_CLOSE. semantics to the Reason Phrase Length field from CONNECTION_CLOSE.
Reason Phrase: This field is identical in format and semantics to Reason Phrase: This field is identical in format and semantics to
the Reason Phrase field from CONNECTION_CLOSE. the Reason Phrase field from CONNECTION_CLOSE.
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The fields in the MAX_DATA frame are as follows: The fields in the MAX_DATA frame are as follows:
Maximum Data: A variable-length integer indicating the maximum Maximum Data: A variable-length integer indicating the maximum
amount of data that can be sent on the entire connection, in units amount of data that can be sent on the entire connection, in units
of octets. of octets.
All data sent in STREAM frames counts toward this limit. The sum of All data sent in STREAM frames counts toward this limit. The sum of
the largest received offsets on all streams - including streams in the largest received offsets on all streams - including streams in
terminal states - MUST NOT exceed the value advertised by a receiver. terminal states - MUST NOT exceed the value advertised by a receiver.
An endpoint MUST terminate a connection with a An endpoint MUST terminate a connection with a FLOW_CONTROL_ERROR
QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA error if it receives more error if it receives more data than the maximum data value that it
data than the maximum data value that it has sent, unless this is a has sent, unless this is a result of a change in the initial limits
result of a change in the initial limits (see Section 6.6.2). (see Section 6.6.2).
7.7. MAX_STREAM_DATA Frame 7.7. MAX_STREAM_DATA Frame
The MAX_STREAM_DATA frame (type=0x05) is used in flow control to The MAX_STREAM_DATA frame (type=0x05) is used in flow control to
inform a peer of the maximum amount of data that can be sent on a inform a peer of the maximum amount of data that can be sent on a
stream. stream.
An endpoint that receives a MAX_STREAM_DATA frame for a receive-only An endpoint that receives a MAX_STREAM_DATA frame for a receive-only
stream MUST terminate the connection with error PROTOCOL_VIOLATION. stream MUST terminate the connection with error PROTOCOL_VIOLATION.
skipping to change at page 72, line 50 skipping to change at page 75, line 50
Stream ID: A variable-length integer indicating the highest stream Stream ID: A variable-length integer indicating the highest stream
ID that the sender was permitted to open. ID that the sender was permitted to open.
7.13. NEW_CONNECTION_ID Frame 7.13. NEW_CONNECTION_ID Frame
An endpoint sends a NEW_CONNECTION_ID frame (type=0x0b) to provide An endpoint sends a NEW_CONNECTION_ID frame (type=0x0b) to provide
its peer with alternative connection IDs that can be used to break its peer with alternative connection IDs that can be used to break
linkability when migrating connections (see Section 6.11.5). linkability when migrating connections (see Section 6.11.5).
The NEW_CONNECTION_ID is as follows: The NEW_CONNECTION_ID 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence (i) ... | Length (8) | Sequence Number (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length (8) | Connection ID (32..144) ... | Connection ID (32..144) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ + + +
| | | |
+ Stateless Reset Token (128) + + Stateless Reset Token (128) +
| | | |
+ + + +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are: The fields are:
Sequence: A variable-length integer. This value starts at 0 and
increases by 1 for each connection ID that is provided by the
server. The connection ID that is assigned during the handshake
is assumed to have a sequence of -1. That is, the value selected
during the handshake comes immediately before the first value that
a server can send.
Length: An 8-bit unsigned integer containing the length of the Length: An 8-bit unsigned integer containing the length of the
connection ID. Values less than 4 and greater than 18 are invalid connection ID. Values less than 4 and greater than 18 are invalid
and MUST be treated as a connection error of type and MUST be treated as a connection error of type
PROTOCOL_VIOLATION. PROTOCOL_VIOLATION.
Sequence Number: The sequence number assigned to the connection ID
by the sender. See Section 6.1.1.
Connection ID: A connection ID of the specified length. Connection ID: A connection ID of the specified length.
Stateless Reset Token: A 128-bit value that will be used to for a Stateless Reset Token: A 128-bit value that will be used for a
stateless reset when the associated connection ID is used (see stateless reset when the associated connection ID is used (see
Section 6.13.4). Section 6.13.4).
An endpoint MUST NOT send this frame if it currently requires that An endpoint MUST NOT send this frame if it currently requires that
its peer send packets with a zero-length Destination Connection ID. its peer send packets with a zero-length Destination Connection ID.
Changing the length of a connection ID to or from zero-length makes Changing the length of a connection ID to or from zero-length makes
it difficult to identify when the value of the connection ID changed. it difficult to identify when the value of the connection ID changed.
An endpoint that is sending packets with a zero-length Destination An endpoint that is sending packets with a zero-length Destination
Connection ID MUST treat receipt of a NEW_CONNECTION_ID frame as a Connection ID MUST treat receipt of a NEW_CONNECTION_ID frame as a
connection error of type PROTOCOL_VIOLATION. connection error of type PROTOCOL_VIOLATION.
7.14. STOP_SENDING Frame Transmission errors, timeouts and retransmissions might cause the
same NEW_CONNECTION_ID frame to be received multiple times. Receipt
of the same frame multiple times MUST NOT be treated as a connection
error. A receiver can use the sequence number supplied in the
NEW_CONNECTION_ID frame to identify new connection IDs from old ones.
If an endpoint receives a NEW_CONNECTION_ID frame that repeats a
previously issued connection ID with a different Stateless Reset
Token or a different sequence number, the endpoint MAY treat that
receipt as a connection error of type PROTOCOL_VIOLATION.
7.14. RETIRE_CONNECTION_ID Frame
An endpoint sends a RETIRE_CONNECTION_ID frame (type=0x1b) to
indicate that it will no longer use a connection ID that was issued
by its peer. This may include the connection ID provided during the
handshake. Sending a RETIRE_CONNECTION_ID frame also serves as a
request to the peer to send additional connection IDs for future use
(see Section 6.1). New connection IDs can be delivered to a peer
using the NEW_CONNECTION_ID frame (Section 7.13).
Retiring a connection ID invalidates the stateless reset token
associated with that connection ID.
The RETIRE_CONNECTION_ID frame is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are:
Sequence Number: The sequence number of the connection ID being
retired. See Section 6.1.2.
Receipt of a RETIRE_CONNECTION_ID frame containing a sequence number
greater than any previously sent to the peer MAY be treated as a
connection error of type PROTOCOL_VIOLATION.
An endpoint cannot send this frame if it was provided with a zero-
length connection ID by its peer. An endpoint that provides a zero-
length connection ID MUST treat receipt of a RETIRE_CONNECTION_ID
frame as a connection error of type PROTOCOL_VIOLATION.
7.15. 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.
Receipt of a STOP_SENDING frame is only valid for a send stream that Receipt of a STOP_SENDING frame is only valid for a send stream that
exists and is not in the "Ready" state (see Section 9.2.1). exists and is not in the "Ready" state (see Section 9.2.1).
Receiving a STOP_SENDING frame for a send stream that is "Ready" or Receiving a STOP_SENDING frame for a send stream that is "Ready" or
non-existent MUST be treated as a connection error of type non-existent MUST be treated as a connection error of type
skipping to change at page 74, line 38 skipping to change at page 78, line 27
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are: The fields are:
Stream ID: A variable-length integer carrying the Stream ID of the Stream ID: A variable-length integer carrying the Stream ID of the
stream being ignored. stream being ignored.
Application Error Code: A 16-bit, application-specified reason the Application Error Code: A 16-bit, application-specified reason the
sender is ignoring the stream (see Section 11.4). sender is ignoring the stream (see Section 11.4).
7.15. ACK Frame 7.16. ACK Frame
Receivers send ACK frames (type=0x0d) to inform senders which packets Receivers send ACK frames (types 0x1a and 0x1b) to inform senders of
they have received and processed. The ACK frame contains any number packets they have received and processed. The ACK frame contains one
of ACK blocks. ACK blocks are ranges of acknowledged packets. or more ACK Blocks. ACK Blocks are ranges of acknowledged packets.
If the frame type is 0x1b, ACK frames also contain the sum of ECN
marks received on the connection up until this point.
QUIC acknowledgements are irrevocable. Once acknowledged, a packet QUIC acknowledgements are irrevocable. Once acknowledged, a packet
remains acknowledged, even if it does not appear in a future ACK remains acknowledged, even if it does not appear in a future ACK
frame. This is unlike TCP SACKs ([RFC2018]). frame. This is unlike TCP SACKs ([RFC2018]).
It is expected that a sender will reuse the same packet number across It is expected that a sender will reuse the same packet number across
different packet number spaces. ACK frames only acknowledge the different packet number spaces. ACK frames only acknowledge the
packet numbers that were transmitted by the sender in the same packet packet numbers that were transmitted by the sender in the same packet
number space of the packet that the ACK was received in. number space of the packet that the ACK was received in.
A client MUST NOT acknowledge Retry packets. Retry packets include Version Negotiation and Retry packets cannot be acknowledged because
the packet number from the Initial packet it responds to. Version they do not contain a packet number. Rather than relying on ACK
Negotiation packets cannot be acknowledged because they do not frames, these packets are implicitly acknowledged by the next Initial
contain a packet number. Rather than relying on ACK frames, these packet sent by the client.
packets are implicitly acknowledged by the next Initial packet sent
by the client.
An ACK frame is shown below. An ACK frame is shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Largest Acknowledged (i) ... | Largest Acknowledged (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Delay (i) ... | ACK Delay (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Block Count (i) ... | ACK Block Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Blocks (*) ... | ACK Blocks (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [ECN Section] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: ACK Frame Format Figure 12: ACK Frame Format
The fields in the ACK frame are as follows: The fields in the ACK frame are as follows:
Largest Acknowledged: A variable-length integer representing the Largest Acknowledged: A variable-length integer representing the
largest packet number the peer is acknowledging; this is usually largest packet number the peer is acknowledging; this is usually
the largest packet number that the peer has received prior to the largest packet number that the peer has received prior to
generating the ACK frame. Unlike the packet number in the QUIC generating the ACK frame. Unlike the packet number in the QUIC
long or short header, the value in an ACK frame is not truncated. long or short header, the value in an ACK frame is not truncated.
ACK Delay: A variable-length integer including the time in ACK Delay: A variable-length integer including the time in
microseconds that the largest acknowledged packet, as indicated in microseconds that the largest acknowledged packet, as indicated in
the Largest Acknowledged field, was received by this peer to when the Largest Acknowledged field, was received by this peer to when
this ACK was sent. The value of the ACK Delay field is scaled by this ACK was sent. The value of the ACK Delay field is scaled by
multiplying the encoded value by the 2 to the power of the value multiplying the encoded value by 2 to the power of the value of
of the "ack_delay_exponent" transport parameter set by the sender the "ack_delay_exponent" transport parameter set by the sender of
of the ACK frame. The "ack_delay_exponent" defaults to 3, or a the ACK frame. The "ack_delay_exponent" defaults to 3, or a
multiplier of 8 (see Section 6.6.1). Scaling in this fashion multiplier of 8 (see Section 6.6.1). Scaling in this fashion
allows for a larger range of values with a shorter encoding at the allows for a larger range of values with a shorter encoding at the
cost of lower resolution. cost of lower resolution.
ACK Block Count: A variable-length integer specifying the number of ACK Block Count: A variable-length integer specifying the number of
Additional ACK Block (and Gap) fields after the First ACK Block. Additional ACK Block (and Gap) fields after the First ACK Block.
ACK Blocks: Contains one or more blocks of packet numbers which have ACK Blocks: Contains one or more blocks of packet numbers which have
been successfully received, see Section 7.15.1. been successfully received, see Section 7.16.1.
7.15.1. ACK Block Section 7.16.1. ACK Block Section
The ACK Block Section consists of alternating Gap and ACK Block The ACK Block Section consists of alternating Gap and ACK Block
fields in descending packet number order. A First Ack Block field is fields in descending packet number order. A First Ack Block field is
followed by a variable number of alternating Gap and Additional ACK followed by a variable number of alternating Gap and Additional ACK
Blocks. The number of Gap and Additional ACK Block fields is Blocks. The number of Gap and Additional ACK Block fields is
determined by the ACK Block Count field. determined by the ACK Block Count field.
Gap and ACK Block fields use a relative integer encoding for Gap and ACK Block fields use a relative integer encoding for
efficiency. Though each encoded value is positive, the values are efficiency. Though each encoded value is positive, the values are
subtracted, so that each ACK Block describes progressively lower- subtracted, so that each ACK Block describes progressively lower-
numbered packets. As long as contiguous ranges of packets are small, numbered packets. As long as contiguous ranges of packets are small,
the variable-length integer encoding ensures that each range can be the variable-length integer encoding ensures that each range can be
expressed in a small number of octets. expressed in a small number of octets.
The ACK frame uses the least significant bit(bit (that is, type 0x1b)
to indicate ECN feedback and report receipt of packets with ECN
codepoints of ECT(0), ECT(1), or CE in the packet's IP 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| First ACK Block (i) ... | First ACK Block (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Gap (i) ... | Gap (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Additional ACK Block (i) ... | Additional ACK Block (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Gap (i) ... | Gap (i) ...
skipping to change at page 77, line 5 skipping to change at page 80, line 49
indicating the number of acknowledged packets that precede the indicating the number of acknowledged packets that precede the
largest packet number in that block. A value of zero indicates that largest packet number in that block. A value of zero indicates that
only the largest packet number is acknowledged. Larger ACK Block only the largest packet number is acknowledged. Larger ACK Block
values indicate a larger range, with corresponding lower values for values indicate a larger range, with corresponding lower values for
the smallest packet number in the range. Thus, given a largest the smallest packet number in the range. Thus, given a largest
packet number for the ACK, the smallest value is determined by the packet number for the ACK, the smallest value is determined by the
formula: formula:
smallest = largest - ack_block smallest = largest - ack_block
The range of packets that are acknowledged by the ACK block include The range of packets that are acknowledged by the ACK Block include
the range from the smallest packet number to the largest, inclusive. the range from the smallest packet number to the largest, inclusive.
The largest value for the First ACK Block is determined by the The largest value for the First ACK Block is determined by the
Largest Acknowledged field; the largest for Additional ACK Blocks is Largest Acknowledged field; the largest for Additional ACK Blocks is
determined by cumulatively subtracting the size of all preceding ACK determined by cumulatively subtracting the size of all preceding ACK
Blocks and Gaps. Blocks and Gaps.
Each Gap indicates a range of packets that are not being Each Gap indicates a range of packets that are not being
acknowledged. The number of packets in the gap is one higher than acknowledged. The number of packets in the gap is one higher than
the encoded value of the Gap Field. the encoded value of the Gap Field.
The value of the Gap field establishes the largest packet number The value of the Gap field establishes the largest packet number
value for the ACK block that follows the gap using the following value for the ACK Block that follows the gap using the following
formula: formula:
largest = previous_smallest - gap - 2 largest = previous_smallest - gap - 2
If the calculated value for largest or smallest packet number for any If the calculated value for largest or smallest packet number for any
ACK Block is negative, an endpoint MUST generate a connection error ACK Block is negative, an endpoint MUST generate a connection error
of type FRAME_ENCODING_ERROR indicating an error in an ACK frame. of type FRAME_ENCODING_ERROR indicating an error in an ACK frame.
The fields in the ACK Block Section are: The fields in the ACK Block Section are:
First ACK Block: A variable-length integer indicating the number of First ACK Block: A variable-length integer indicating the number of
contiguous packets preceding the Largest Acknowledged that are contiguous packets preceding the Largest Acknowledged that are
being acknowledged. being acknowledged.
Gap (repeated): A variable-length integer indicating the number of Gap (repeated): A variable-length integer indicating the number of
contiguous unacknowledged packets preceding the packet number one contiguous unacknowledged packets preceding the packet number one
lower than the smallest in the preceding ACK Block. lower than the smallest in the preceding ACK Block.
ACK Block (repeated): A variable-length integer indicating the Additional ACK Block (repeated): A variable-length integer
number of contiguous acknowledged packets preceding the largest indicating the number of contiguous acknowledged packets preceding
packet number, as determined by the preceding Gap. the largest packet number, as determined by the preceding Gap.
7.15.2. Sending ACK Frames 7.16.2. ECN section
The ECN section should only be parsed when the ACK frame type byte is
0x1b. The ECN section consists of 3 ECN counters as shown below.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECT(0) Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECT(1) Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECN-CE Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ECT(0) Count: A variable-length integer representing the total
number packets received with the ECT(0) codepoint.
ECT(1) Count: A variable-length integer representing the total
number packets received with the ECT(1) codepoint.
CE Count: A variable-length integer representing the total number
packets received with the CE codepoint.
7.16.3. Sending ACK Frames
Implementations MUST NOT generate packets that only contain ACK Implementations MUST NOT generate packets that only contain ACK
frames in response to packets which only contain ACK frames. frames in response to packets which only contain ACK and PADDING
However, they MUST acknowledge packets containing only ACK frames frames. However, they MUST acknowledge packets containing only ACK
when sending ACK frames in response to other packets. and PADDING frames when sending ACK frames in response to other
Implementations MUST NOT send more than one packet containing only packets. Implementations MUST NOT send more than one packet
ACK frames per received packet that contains frames other than ACK containing only an ACK frame per received packet that contains frames
frames. Packets containing non-ACK frames MUST be acknowledged other than ACK and PADDING frames. Packets containing frames besides
immediately or when a delayed ack timer expires. ACK and PADDING MUST be acknowledged immediately or when a delayed
ack timer expires.
To limit ACK blocks to those that have not yet been received by the The receiver's delayed acknowledgment timer SHOULD NOT exceed the
current RTT estimate or the value it indicates in the "max_ack_delay"
transport parameter. This ensures an acknowledgment is sent at least
once per RTT when packets needing acknowledgement are received. The
sender can use the receiver's "max_ack_delay" value in determining
timeouts for timer-based retransmission.
An acknowledgment SHOULD be sent immediately after receiving 2
packets that require acknowledgement, unless multiple packets are
received together.
To limit ACK Blocks to those that have not yet been received by the
sender, the receiver SHOULD track which ACK frames have been sender, the receiver SHOULD track which ACK frames have been
acknowledged by its peer. Once an ACK frame has been acknowledged, acknowledged by its peer. Once an ACK frame has been acknowledged,
the packets it acknowledges SHOULD NOT be acknowledged again. the packets it acknowledges SHOULD NOT be acknowledged again.
Because ACK frames are not sent in response to ACK-only packets, a Because ACK frames are not sent in response to ACK-only packets, a
receiver that is only sending ACK frames will only receive receiver that is only sending ACK frames will only receive
acknowledgements for its packets if the sender includes them in acknowledgements for its packets if the sender includes them in
packets with non-ACK frames. A sender SHOULD bundle ACK frames with packets with non-ACK frames. A sender SHOULD bundle ACK frames with
other frames when possible. other frames when possible.
Endpoints can only acknowledge packets sent in a particular packet Endpoints can only acknowledge packets sent in a particular packet
number space by sending ACK frames in packets from the same packet number space by sending ACK frames in packets from the same packet
number space. number space.
To limit receiver state or the size of ACK frames, a receiver MAY To limit receiver state or the size of ACK frames, a receiver MAY
limit the number of ACK blocks it sends. A receiver can do this even limit the number of ACK Blocks it sends. A receiver can do this even
without receiving acknowledgment of its ACK frames, with the without receiving acknowledgment of its ACK frames, with the
knowledge this could cause the sender to unnecessarily retransmit knowledge this could cause the sender to unnecessarily retransmit
some data. Standard QUIC [QUIC-RECOVERY] algorithms declare packets some data. Standard QUIC [QUIC-RECOVERY] algorithms declare packets
lost after sufficiently newer packets are acknowledged. Therefore, lost after sufficiently newer packets are acknowledged. Therefore,
the receiver SHOULD repeatedly acknowledge newly received packets in the receiver SHOULD repeatedly acknowledge newly received packets in
preference to packets received in the past. preference to packets received in the past.
7.15.3. ACK Frames and Packet Protection 7.16.4. ACK Frames and Packet Protection
ACK frames MUST only be carried in a packet that has the same packet ACK frames MUST only be carried in a packet that has the same packet
number space as the packet being ACKed (see Section 4.8). For number space as the packet being ACKed (see Section 4.8). For
instance, packets that are protected with 1-RTT keys MUST be instance, packets that are protected with 1-RTT keys MUST be
acknowledged in packets that are also protected with 1-RTT keys. acknowledged in packets that are also protected with 1-RTT keys.
Packets that a client sends with 0-RTT packet protection MUST be Packets that a client sends with 0-RTT packet protection MUST be
acknowledged by the server in packets protected by 1-RTT keys. This acknowledged by the server in packets protected by 1-RTT keys. This
can mean that the client is unable to use these acknowledgments if can mean that the client is unable to use these acknowledgments if
the server cryptographic handshake messages are delayed or lost. the server cryptographic handshake messages are delayed or lost.
Note that the same limitation applies to other data sent by the Note that the same limitation applies to other data sent by the
server protected by the 1-RTT keys. server protected by the 1-RTT keys.
Endpoints SHOULD send acknowledgments for packets containing CRYPTO Endpoints SHOULD send acknowledgments for packets containing CRYPTO
frames with a reduced delay; see Section 4.3.1 of [QUIC-RECOVERY]. frames with a reduced delay; see Section 4.3.1 of [QUIC-RECOVERY].
7.16. ACK_ECN Frame
The ACK_ECN frame (type=0x1a) is used by an endpoint that supports
ECN to acknowledge packets received with ECN codepoints of ECT(0),
ECT(1), or CE in the packet's IP header.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Largest Acknowledged (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Delay (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECT(0) Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECT(1) Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECN-CE Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Block Count (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACK Blocks (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: ACK_ECN Frame Format
An ACK_ECN frame contains all the elements of the ACK frame
(Section 7.15) with the addition of three counts following the ACK
Delay field.
ECT(0) Count: A variable-length integer representing the total
number packets received with the ECT(0) codepoint.
ECT(1) Count: A variable-length integer representing the total
number packets received with the ECT(1) codepoint.
CE Count: A variable-length integer representing the total number
packets received with the CE codepoint.
7.17. PATH_CHALLENGE Frame 7.17. PATH_CHALLENGE Frame
Endpoints can use PATH_CHALLENGE frames (type=0x0e) to check Endpoints can use PATH_CHALLENGE frames (type=0x0e) to check
reachability to the peer and for path validation during connection reachability to the peer and for path validation during connection
establishment and connection migration. migration.
PATH_CHALLENGE frames contain an 8-byte payload. PATH_CHALLENGE frames contain an 8-byte payload.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Data (8) + + Data (8) +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 81, line 40 skipping to change at page 85, line 33
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (i) ... | Stream ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Offset (i)] ... | [Offset (i)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Length (i)] ... | [Length (i)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream Data (*) ... | Stream Data (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15: STREAM Frame Format Figure 14: STREAM Frame Format
The STREAM frame contains the following fields: The STREAM frame contains the following fields:
Stream ID: A variable-length integer indicating the stream ID of the Stream ID: A variable-length integer indicating the stream ID of the
stream (see Section 9.1). stream (see Section 9.1).
Offset: A variable-length integer specifying the byte offset in the Offset: A variable-length integer specifying the byte offset in the
stream for the data in this STREAM frame. This field is present stream for the data in this STREAM frame. This field is present
when the OFF bit is set to 1. When the Offset field is absent, when the OFF bit is set to 1. When the Offset field is absent,
the offset is 0. the offset is 0.
skipping to change at page 83, line 15 skipping to change at page 86, line 48
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Offset (i) ... | Offset (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length (i) ... | Length (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Crypto Data (*) ... | Crypto Data (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16: CRYPTO Frame Format Figure 15: CRYPTO Frame Format
The CRYPTO frame contains the following fields: The CRYPTO frame contains the following fields:
Offset: A variable-length integer specifying the byte offset in the Offset: A variable-length integer specifying the byte offset in the
stream for the data in this CRYPTO frame. stream for the data in this CRYPTO frame.
Length: A variable-length integer specifying the length of the Length: A variable-length integer specifying the length of the
Crypto Data field in this CRYPTO frame. Crypto Data field in this CRYPTO frame.
Crypto Data: The cryptographic message data. Crypto Data: The cryptographic message data.
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use knowledge about application sending behavior or heuristics to use knowledge about application sending behavior or heuristics to
determine whether and for how long to wait. This waiting period is determine whether and for how long to wait. This waiting period is
an implementation decision, and an implementation should be careful an implementation decision, and an implementation should be careful
to delay conservatively, since any delay is likely to increase to delay conservatively, since any delay is likely to increase
application-visible latency. application-visible latency.
8.1. Packet Processing and Acknowledgment 8.1. Packet Processing and Acknowledgment
A packet MUST NOT be acknowledged until packet protection has been A packet MUST NOT be acknowledged until packet protection has been
successfully removed and all frames contained in the packet have been successfully removed and all frames contained in the packet have been
processed. Any stream state transitions triggered by the frame MUST processed. For STREAM frames, this means the data has been enqueued
have occurred. For STREAM frames, this means the data has been in preparation to be received by the application protocol, but it
enqueued in preparation to be received by the application protocol, does not require that data is delivered and consumed.
but it does not require that data is delivered and consumed.
Once the packet has been fully processed, a receiver acknowledges Once the packet has been fully processed, a receiver acknowledges
receipt by sending one or more ACK frames containing the packet receipt by sending one or more ACK frames containing the packet
number of the received packet. To avoid creating an indefinite number of the received packet. To avoid creating an indefinite
feedback loop, an endpoint MUST NOT send an ACK frame in response to feedback loop, an endpoint MUST NOT send an ACK frame in response to
a packet containing only ACK or PADDING frames, even if there are a packet containing only ACK or PADDING frames, even if there are
packet gaps which precede the received packet. The endpoint MUST packet gaps which precede the received packet. The endpoint MUST
acknowledge packets containing only ACK or PADDING frames in the next acknowledge packets containing only ACK or PADDING frames in the next
ACK frame that it sends. ACK frame that it sends.
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whole. The same applies to the frames that are contained within lost whole. The same applies to the frames that are contained within lost
packets. Instead, the information that might be carried in frames is packets. Instead, the information that might be carried in frames is
sent again in new frames as needed. sent again in new frames as needed.
New frames and packets are used to carry information that is New frames and packets are used to carry information that is
determined to have been lost. In general, information is sent again determined to have been lost. In general, information is sent again
when a packet containing that information is determined to be lost when a packet containing that information is determined to be lost
and sending ceases when a packet containing that information is and sending ceases when a packet containing that information is
acknowledged. acknowledged.
o Data sent in CRYPTO frames are retransmitted according to the o Data sent in CRYPTO frames is retransmitted according to the rules
rules in [QUIC-RECOVERY], until either all data has been in [QUIC-RECOVERY], until either all data has been acknowledged or
acknowledged or the crypto state machine implicitly knows that the the crypto state machine implicitly knows that the peer received
peer received the data. the data.
o Application data sent in STREAM frames is retransmitted in new o Application data sent in STREAM frames is retransmitted in new
STREAM frames unless the endpoint has sent a RST_STREAM for that STREAM frames unless the endpoint has sent a RST_STREAM for that
stream. Once an endpoint sends a RST_STREAM frame, no further stream. Once an endpoint sends a RST_STREAM frame, no further
STREAM frames are needed. STREAM frames are needed.
o The most recent set of acknowledgments are sent in ACK frames. An o The most recent set of acknowledgments are sent in ACK frames. An
ACK frame SHOULD contain all unacknowledged acknowledgments, as ACK frame SHOULD contain all unacknowledged acknowledgments, as
described in Section 7.15.2. described in Section 7.16.3.
o Cancellation of stream transmission, as carried in a RST_STREAM o Cancellation of stream transmission, as carried in a RST_STREAM
frame, is sent until acknowledged or until all stream data is frame, is sent until acknowledged or until all stream data is
acknowledged by the peer (that is, either the "Reset Recvd" or acknowledged by the peer (that is, either the "Reset Recvd" or
"Data Recvd" state is reached on the send stream). The content of "Data Recvd" state is reached on the send stream). The content of
a RST_STREAM frame MUST NOT change when it is sent again. a RST_STREAM frame MUST NOT change when it is sent again.
o Similarly, a request to cancel stream transmission, as encoded in o Similarly, a request to cancel stream transmission, as encoded in
a STOP_SENDING frame, is sent until the receive stream enters a STOP_SENDING frame, is sent until the receive stream enters
either a "Data Recvd" or "Reset Recvd" state, see Section 9.3. either a "Data Recvd" or "Reset Recvd" state, see Section 9.3.
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or until there is no remaining need for liveness or path or until there is no remaining need for liveness or path
validation checking. PATH_CHALLENGE frames include a different validation checking. PATH_CHALLENGE frames include a different
payload each time they are sent. payload each time they are sent.
o Responses to path validation using PATH_RESPONSE frames are sent o Responses to path validation using PATH_RESPONSE frames are sent
just once. A new PATH_CHALLENGE frame will be sent if another just once. A new PATH_CHALLENGE frame will be sent if another
PATH_RESPONSE frame is needed. PATH_RESPONSE frame is needed.
o New connection IDs are sent in NEW_CONNECTION_ID frames and o New connection IDs are sent in NEW_CONNECTION_ID frames and
retransmitted if the packet containing them is lost. retransmitted if the packet containing them is lost.
Retransmissions of this frame carry the same sequence number
value. Likewise, retired connection IDs are sent in
RETIRE_CONNECTION_ID frames and retransmitted if the packet
containing them is lost.
o PADDING frames contain no information, so lost PADDING frames do o PADDING frames contain no information, so lost PADDING frames do
not require repair. not require repair.
Upon detecting losses, a sender MUST take appropriate congestion Upon detecting losses, a sender MUST take appropriate congestion
control action. The details of loss detection and congestion control control action. The details of loss detection and congestion control
are described in [QUIC-RECOVERY]. are described in [QUIC-RECOVERY].
8.3. Packet Size 8.3. Packet Size
The QUIC packet size includes the QUIC header and integrity check, The QUIC packet size includes the QUIC header and integrity check,
but not the UDP or IP header. but not the UDP or IP header.
Clients MUST ensure that the first Initial packet it sends is sent in Clients MUST ensure that the first Initial packet they send is sent
a UDP datagram that is at least 1200 octets. Padding the Initial in a UDP datagram that is at least 1200 octets. Padding the Initial
packet or including a 0-RTT packet in the same datagram are ways to packet or including a 0-RTT packet in the same datagram are ways to
meet this requirement. Sending a UDP datagram of this size ensures meet this requirement. Sending a UDP datagram of this size ensures
that the network path supports a reasonable Maximum Transmission Unit that the network path supports a reasonable Maximum Transmission Unit
(MTU), and helps reduce the amplitude of amplification attacks caused (MTU), and helps reduce the amplitude of amplification attacks caused
by server responses toward an unverified client address. by server responses toward an unverified client address.
The datagram containing the first Initial packet from a client MAY The datagram containing the first Initial packet from a client MAY
exceed 1200 octets if the client believes that the Path Maximum exceed 1200 octets if the client believes that the Path Maximum
Transmission Unit (PMTU) supports the size that it chooses. Transmission Unit (PMTU) supports the size that it chooses.
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All QUIC packets SHOULD be sized to fit within the estimated PMTU to All QUIC packets SHOULD be sized to fit within the estimated PMTU to
avoid IP fragmentation or packet drops. To optimize bandwidth avoid IP fragmentation or packet drops. To optimize bandwidth
efficiency, endpoints SHOULD use Packetization Layer PMTU Discovery efficiency, endpoints SHOULD use Packetization Layer PMTU Discovery
([PLPMTUD]). Endpoints MAY use PMTU Discovery ([PMTUDv4], [PMTUDv6]) ([PLPMTUD]). Endpoints MAY use PMTU Discovery ([PMTUDv4], [PMTUDv6])
for detecting the PMTU, setting the PMTU appropriately, and storing for detecting the PMTU, setting the PMTU appropriately, and storing
the result of previous PMTU determinations. the result of previous PMTU determinations.
In the absence of these mechanisms, QUIC endpoints SHOULD NOT send IP In the absence of these mechanisms, QUIC endpoints SHOULD NOT send IP
packets larger than 1280 octets. Assuming the minimum IP header packets larger than 1280 octets. Assuming the minimum IP header
size, this results in a QUIC packet size of 1232 octets for IPv6 and size, this results in a QUIC packet size of 1232 octets for IPv6 and
1252 octets for IPv4. Some QUIC implementations MAY wish to be more 1252 octets for IPv4. Some QUIC implementations MAY be more
conservative in computing allowed QUIC packet size given unknown conservative in computing allowed QUIC packet size given unknown
tunneling overheads or IP header options. tunneling overheads or IP header options.
QUIC endpoints that implement any kind of PMTU discovery SHOULD QUIC endpoints that implement any kind of PMTU discovery SHOULD
maintain an estimate for each combination of local and remote IP maintain an estimate for each combination of local and remote IP
addresses. Each pairing of local and remote addresses could have a addresses. Each pairing of local and remote addresses could have a
different maximum MTU in the path. different maximum MTU in the path.
QUIC depends on the network path supporting a MTU of at least 1280 QUIC depends on the network path supporting an MTU of at least 1280
octets. This is the IPv6 minimum MTU and therefore also supported by octets. This is the IPv6 minimum MTU and therefore also supported by
most modern IPv4 networks. An endpoint MUST NOT reduce its MTU below most modern IPv4 networks. An endpoint MUST NOT reduce its MTU below
this number, even if it receives signals that indicate a smaller this number, even if it receives signals that indicate a smaller
limit might exist. limit might exist.
If a QUIC endpoint determines that the PMTU between any pair of local If a QUIC endpoint determines that the PMTU between any pair of local
and remote IP addresses has fallen below 1280 octets, it MUST and remote IP addresses has fallen below 1280 octets, it MUST
immediately cease sending QUIC packets on the affected path. This immediately cease sending QUIC packets on the affected path. This
could result in termination of the connection if an alternative path could result in termination of the connection if an alternative path
cannot be found. cannot be found.
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increases in the size of probe packets. As QUIC probe packets need increases in the size of probe packets. As QUIC probe packets need
not contain application data, aggressive increases in probe size not contain application data, aggressive increases in probe size
carry fewer consequences. carry fewer consequences.
9. Streams: QUIC's Data Structuring Abstraction 9. Streams: QUIC's Data Structuring Abstraction
Streams in QUIC provide a lightweight, ordered byte-stream Streams in QUIC provide a lightweight, ordered byte-stream
abstraction. abstraction.
There are two basic types of stream in QUIC. Unidirectional streams There are two basic types of stream in QUIC. Unidirectional streams
carry data in one direction only; bidirectional streams allow for carry data in one direction: from the initiator of the stream to its
data to be sent in both directions. Different stream identifiers are peer; bidirectional streams allow for data to be sent in both
used to distinguish between unidirectional and bidirectional streams, directions. Different stream identifiers are used to distinguish
as well as to create a separation between streams that are initiated between unidirectional and bidirectional streams, as well as to
by the client and server (see Section 9.1). create a separation between streams that are initiated by the client
and server (see Section 9.1).
Either type of stream can be created by either endpoint, can Either type of stream can be created by either endpoint, can
concurrently send data interleaved with other streams, and can be concurrently send data interleaved with other streams, and can be
cancelled. cancelled.
Stream offsets allow for the octets on a stream to be placed in Stream offsets allow for the octets on a stream to be placed in
order. An endpoint MUST be capable of delivering data received on a order. An endpoint MUST be capable of delivering data received on a
stream in order. Implementations MAY choose to offer the ability to stream in order. Implementations MAY choose to offer the ability to
deliver data out of order. There is no means of ensuring ordering deliver data out of order. There is no means of ensuring ordering
between octets on different streams. between octets on different streams.
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of frames can be sent and the reactions that are expected when of frames can be sent and the reactions that are expected when
different types of frames are received. Though these state different types of frames are received. Though these state
machines are intended to be useful in implementing QUIC, these machines are intended to be useful in implementing QUIC, these
states aren't intended to constrain implementations. An states aren't intended to constrain implementations. An
implementation can define a different state machine as long as its implementation can define a different state machine as long as its
behavior is consistent with an implementation that implements behavior is consistent with an implementation that implements
these states. these states.
9.2.1. Send Stream States 9.2.1. Send Stream States
Figure 17 shows the states for the part of a stream that sends data Figure 16 shows the states for the part of a stream that sends data
to a peer. to a peer.
o o
| Create Stream (Sending) | Create Stream (Sending)
| Create Bidirectional Stream (Receiving) | Create Bidirectional Stream (Receiving)
v v
+-------+ +-------+
| Ready | Send RST_STREAM | Ready | Send RST_STREAM
| |-----------------------. | |-----------------------.
+-------+ | +-------+ |
| | | |
| Send STREAM / | | Send STREAM / |
| STREAM_BLOCKED | | STREAM_BLOCKED |
| |
| Create Bidirectional |
| Stream (Receiving) |
v | v |
+-------+ | +-------+ |
| Send | Send RST_STREAM | | Send | Send RST_STREAM |
| |---------------------->| | |---------------------->|
+-------+ | +-------+ |
| | | |
| Send STREAM + FIN | | Send STREAM + FIN |
v v v v
+-------+ +-------+ +-------+ +-------+
| Data | Send RST_STREAM | Reset | | Data | Send RST_STREAM | Reset |
| Sent +------------------>| Sent | | Sent |------------------>| Sent |
+-------+ +-------+ +-------+ +-------+
| | | |
| Recv All ACKs | Recv ACK | Recv All ACKs | Recv ACK
v v v v
+-------+ +-------+ +-------+ +-------+
| Data | | Reset | | Data | | Reset |
| Recvd | | Recvd | | Recvd | | Recvd |
+-------+ +-------+ +-------+ +-------+
Figure 17: States for Send Streams Figure 16: States for Send Streams
The sending part of stream that the endpoint initiates (types 0 and 2 The sending part of stream that the endpoint initiates (types 0 and 2
for clients, 1 and 3 for servers) is opened by the application or for clients, 1 and 3 for servers) is opened by the application or
application protocol. The "Ready" state represents a newly created application protocol. The "Ready" state represents a newly created
stream that is able to accept data from the application. Stream data stream that is able to accept data from the application. Stream data
might be buffered in this state in preparation for sending. might be buffered in this state in preparation for sending.
The sending part of a bidirectional stream initiated by a peer (type
0 for a server, type 1 for a client) enters the "Ready" state if the
receiving part enters the "Recv" state.
Sending the first STREAM or STREAM_BLOCKED frame causes a send stream Sending the first STREAM or STREAM_BLOCKED frame causes a send stream
to enter the "Send" state. An implementation might choose to defer to enter the "Send" state. An implementation might choose to defer
allocating a Stream ID to a send stream until it sends the first allocating a Stream ID to a send stream until it sends the first
frame and enters this state, which can allow for better stream frame and enters this state, which can allow for better stream
prioritization. prioritization.
The sending part of a bidirectional stream initiated by a peer (type
0 for a server, type 1 for a client) enters the "Ready" state then
immediately transitions to the "Send" state if the receiving part
enters the "Recv" state.
In the "Send" state, an endpoint transmits - and retransmits as In the "Send" state, an endpoint transmits - and retransmits as
necessary - data in STREAM frames. The endpoint respects the flow necessary - data in STREAM frames. The endpoint respects the flow
control limits of its peer, accepting MAX_STREAM_DATA frames. An control limits of its peer, accepting MAX_STREAM_DATA frames. An
endpoint in the "Send" state generates STREAM_BLOCKED frames if it endpoint in the "Send" state generates STREAM_BLOCKED frames if it
encounters flow control limits. encounters flow control limits.
After the application indicates that stream data is complete and a After the application indicates that stream data is complete and a
STREAM frame containing the FIN bit is sent, the send stream enters STREAM frame containing the FIN bit is sent, the send stream enters
the "Data Sent" state. From this state, the endpoint only the "Data Sent" state. From this state, the endpoint only
retransmits stream data as necessary. The endpoint no longer needs retransmits stream data as necessary. The endpoint no longer needs
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An endpoint MAY send a RST_STREAM as the first frame on a send An endpoint MAY send a RST_STREAM as the first frame on a send
stream; this causes the send stream to open and then immediately stream; this causes the send stream to open and then immediately
transition to the "Reset Sent" state. transition to the "Reset Sent" state.
Once a packet containing a RST_STREAM has been acknowledged, the send Once a packet containing a RST_STREAM has been acknowledged, the send
stream enters the "Reset Recvd" state, which is a terminal state. stream enters the "Reset Recvd" state, which is a terminal state.
9.2.2. Receive Stream States 9.2.2. Receive Stream States
Figure 18 shows the states for the part of a stream that receives Figure 17 shows the states for the part of a stream that receives
data from a peer. The states for a receive stream mirror only some data from a peer. The states for a receive stream mirror only some
of the states of the send stream at the peer. A receive stream of the states of the send stream at the peer. A receive stream
doesn't track states on the send stream that cannot be observed, such doesn't track states on the send stream that cannot be observed, such
as the "Ready" state; instead, receive streams track the delivery of as the "Ready" state; instead, receive streams track the delivery of
data to the application or application protocol some of which cannot data to the application or application protocol some of which cannot
be observed by the sender. be observed by the sender.
o o
| Recv STREAM / STREAM_BLOCKED / RST_STREAM | Recv STREAM / STREAM_BLOCKED / RST_STREAM
| Create Bidirectional Stream (Sending) | Create Bidirectional Stream (Sending)
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v v
+-------+ +-------+
| Recv | Recv RST_STREAM | Recv | Recv RST_STREAM
| |-----------------------. | |-----------------------.
+-------+ | +-------+ |
| | | |
| Recv STREAM + FIN | | Recv STREAM + FIN |
v | v |
+-------+ | +-------+ |
| Size | Recv RST_STREAM | | Size | Recv RST_STREAM |
| Known +---------------------->| | Known |---------------------->|
+-------+ | +-------+ |
| | | |
| Recv All Data | | Recv All Data |
v v v v
+-------+ +-------+ +-------+ Recv RST_STREAM +-------+
| Data | Recv RST_STREAM | Reset | | Data |--- (optional) --->| Reset |
| Recvd +<-- (optional) --->| Recvd | | Recvd | Recv All Data | Recvd |
+-------+ +-------+ +-------+<-- (optional) ----+-------+
| | | |
| App Read All Data | App Read RST | App Read All Data | App Read RST
v v v v
+-------+ +-------+ +-------+ +-------+
| Data | | Reset | | Data | | Reset |
| Read | | Read | | Read | | Read |
+-------+ +-------+ +-------+ +-------+
Figure 18: States for Receive Streams Figure 17: States for Receive Streams
The receiving part of a stream initiated by a peer (types 1 and 3 for The receiving part of a stream initiated by a peer (types 1 and 3 for
a client, or 0 and 2 for a server) are created when the first STREAM, a client, or 0 and 2 for a server) are created when the first STREAM,
STREAM_BLOCKED, RST_STREAM, or MAX_STREAM_DATA (bidirectional only, STREAM_BLOCKED, RST_STREAM, or MAX_STREAM_DATA (bidirectional only,
see below) is received for that stream. The initial state for a see below) is received for that stream. The initial state for a
receive stream is "Recv". Receiving a RST_STREAM frame causes the receive stream is "Recv". Receiving a RST_STREAM frame causes the
receive stream to immediately transition to the "Reset Recvd". receive stream to immediately transition to the "Reset Recvd".
The receive stream enters the "Recv" state when the sending part of a The receive stream enters the "Recv" state when the sending part of a
bidirectional stream initiated by the endpoint (type 0 for a client, bidirectional stream initiated by the endpoint (type 0 for a client,
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(Section 7.3). (Section 7.3).
A sender MUST NOT send any of these frames from a terminal state A sender MUST NOT send any of these frames from a terminal state
("Data Recvd" or "Reset Recvd"). A sender MUST NOT send STREAM or ("Data Recvd" or "Reset Recvd"). A sender MUST NOT send STREAM or
STREAM_BLOCKED after sending a RST_STREAM; that is, in the "Reset STREAM_BLOCKED after sending a RST_STREAM; that is, in the "Reset
Sent" state in addition to the terminal states. A receiver could Sent" state in addition to the terminal states. A receiver could
receive any of these frames in any state, but only due to the receive any of these frames in any state, but only due to the
possibility of delayed delivery of packets carrying them. possibility of delayed delivery of packets carrying them.
The receiver of a stream sends MAX_STREAM_DATA (Section 7.7) and The receiver of a stream sends MAX_STREAM_DATA (Section 7.7) and
STOP_SENDING frames (Section 7.14). STOP_SENDING frames (Section 7.15).
The receiver only sends MAX_STREAM_DATA in the "Recv" state. A The receiver only sends MAX_STREAM_DATA in the "Recv" state. A
receiver can send STOP_SENDING in any state where it has not received receiver can send STOP_SENDING in any state where it has not received
a RST_STREAM frame; that is states other than "Reset Recvd" or "Reset a RST_STREAM frame; that is states other than "Reset Recvd" or "Reset
Read". However there is little value in sending a STOP_SENDING frame Read". However there is little value in sending a STOP_SENDING frame
after all stream data has been received in the "Data Recvd" state. A after all stream data has been received in the "Data Recvd" state. A
sender could receive these frames in any state as a result of delayed sender could receive these frames in any state as a result of delayed
delivery of packets. delivery of packets.
9.2.4. Bidirectional Stream States 9.2.4. Bidirectional Stream States
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An endpoint limits the number of concurrently active incoming streams An endpoint limits the number of concurrently active incoming streams
by adjusting the maximum stream ID. An initial value is set in the by adjusting the maximum stream ID. An initial value is set in the
transport parameters (see Section 6.6.1) and is subsequently transport parameters (see Section 6.6.1) and is subsequently
increased by MAX_STREAM_ID frames (see Section 7.8). increased by MAX_STREAM_ID frames (see Section 7.8).
The maximum stream ID is specific to each endpoint and applies only The maximum stream ID is specific to each endpoint and applies only
to the peer that receives the setting. That is, clients specify the to the peer that receives the setting. That is, clients specify the
maximum stream ID the server can initiate, and servers specify the maximum stream ID the server can initiate, and servers specify the
maximum stream ID the client can initiate. Each endpoint may respond maximum stream ID the client can initiate. Each endpoint may respond
on streams initiated by the other peer, regardless of whether it is on streams initiated by the other peer, regardless of whether it is
permitted to initiated new streams. permitted to initiate new streams.
Endpoints MUST NOT exceed the limit set by their peer. An endpoint Endpoints MUST NOT exceed the limit set by their peer. An endpoint
that receives a STREAM frame with an ID greater than the limit it has that receives a STREAM frame with an ID greater than the limit it has
sent MUST treat this as a stream error of type STREAM_ID_ERROR sent MUST treat this as a stream error of type STREAM_ID_ERROR
(Section 11), unless this is a result of a change in the initial (Section 11), unless this is a result of a change in the initial
limits (see Section 6.6.2). limits (see Section 6.6.2).
A receiver cannot renege on an advertisement; that is, once a A receiver cannot renege on an advertisement; that is, once a
receiver advertises a stream ID via a MAX_STREAM_ID frame, receiver advertises a stream ID via a MAX_STREAM_ID frame,
advertising a smaller maximum ID has no effect. A sender MUST ignore advertising a smaller maximum ID has no effect. A sender MUST ignore
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recovery, congestion control, and flow control operate effectively. recovery, congestion control, and flow control operate effectively.
CRYPTO frames SHOULD be prioritized over other streams prior to the CRYPTO frames SHOULD be prioritized over other streams prior to the
completion of the cryptographic handshake. This includes the completion of the cryptographic handshake. This includes the
retransmission of the second flight of client handshake messages, retransmission of the second flight of client handshake messages,
that is, the TLS Finished and any client authentication messages. that is, the TLS Finished and any client authentication messages.
STREAM data in frames determined to be lost SHOULD be retransmitted STREAM data in frames determined to be lost SHOULD be retransmitted
before sending new data, unless application priorities indicate before sending new data, unless application priorities indicate
otherwise. Retransmitting lost stream data can fill in gaps, which otherwise. Retransmitting lost stream data can fill in gaps, which
allows the peer to consume already received data and free up flow allows the peer to consume already received data and free up the flow
control window. control window.
10. Flow Control 10. Flow Control
It is necessary to limit the amount of data that a sender may have It is necessary to limit the amount of data that a sender may have
outstanding at any time, so as to prevent a fast sender from outstanding at any time, so as to prevent a fast sender from
overwhelming a slow receiver, or to prevent a malicious sender from overwhelming a slow receiver, or to prevent a malicious sender from
consuming significant resources at a receiver. This section consuming significant resources at a receiver. This section
describes QUIC's flow-control mechanisms. describes QUIC's flow-control mechanisms.
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FINAL_OFFSET_ERROR (0x6): An endpoint received a STREAM frame FINAL_OFFSET_ERROR (0x6): An endpoint received a STREAM frame
containing data that exceeded the previously established final containing data that exceeded the previously established final
offset. Or an endpoint received a RST_STREAM frame containing a offset. Or an endpoint received a RST_STREAM frame containing a
final offset that was lower than the maximum offset of data that final offset that was lower than the maximum offset of data that
was already received. Or an endpoint received a RST_STREAM frame was already received. Or an endpoint received a RST_STREAM frame
containing a different final offset to the one already containing a different final offset to the one already
established. established.
FRAME_ENCODING_ERROR (0x7): An endpoint received a frame that was FRAME_ENCODING_ERROR (0x7): An endpoint received a frame that was
badly formatted. For instance, an empty STREAM frame that omitted badly formatted. For instance, a frame of an unknown type, or an
the FIN flag, or an ACK frame that has more acknowledgment ranges ACK frame that has more acknowledgment ranges than the remainder
than the remainder of the packet could carry. of the packet could carry.
TRANSPORT_PARAMETER_ERROR (0x8): An endpoint received transport TRANSPORT_PARAMETER_ERROR (0x8): An endpoint received transport
parameters that were badly formatted, included an invalid value, parameters that were badly formatted, included an invalid value,
was absent even though it is mandatory, was present though it is was absent even though it is mandatory, was present though it is
forbidden, or is otherwise in error. forbidden, or is otherwise in error.
VERSION_NEGOTIATION_ERROR (0x9): An endpoint received transport VERSION_NEGOTIATION_ERROR (0x9): An endpoint received transport
parameters that contained version negotiation parameters that parameters that contained version negotiation parameters that
disagreed with the version negotiation that it performed. This disagreed with the version negotiation that it performed. This
error code indicates a potential version downgrade attack. error code indicates a potential version downgrade attack.
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server sees an acknowledgment for a packet that was never sent, the server sees an acknowledgment for a packet that was never sent, the
connection can be aborted. connection can be aborted.
The second mitigation is that the server can require that The second mitigation is that the server can require that
acknowledgments for sent packets match the encryption level of the acknowledgments for sent packets match the encryption level of the
sent packet. This mitigation is useful if the connection has an sent packet. This mitigation is useful if the connection has an
ephemeral forward-secure key that is generated and used for every new ephemeral forward-secure key that is generated and used for every new
connection. If a packet sent is protected with a forward-secure key, connection. If a packet sent is protected with a forward-secure key,
then any acknowledgments that are received for them MUST also be then any acknowledgments that are received for them MUST also be
forward-secure protected. Since the attacker will not have the forward-secure protected. Since the attacker will not have the
forward secure key, the attacker will not be able to generate forward-secure key, the attacker will not be able to generate
forward-secure protected packets with ACK frames. forward-secure protected packets with ACK frames.
12.3. Optimistic ACK Attack 12.3. Optimistic ACK Attack
An endpoint that acknowledges packets it has not received might cause An endpoint that acknowledges packets it has not received might cause
a congestion controller to permit sending at rates beyond what the a congestion controller to permit sending at rates beyond what the
network supports. An endpoint MAY skip packet numbers when sending network supports. An endpoint MAY skip packet numbers when sending
packets to detect this behavior. An endpoint can then immediately packets to detect this behavior. An endpoint can then immediately
close the connection with a connection error of type close the connection with a connection error of type
PROTOCOL_VIOLATION (see Section 6.13.3). PROTOCOL_VIOLATION (see Section 6.13.3).
skipping to change at page 109, line 39 skipping to change at page 113, line 7
QUIC deployments SHOULD provide mitigations for the Slowloris QUIC deployments SHOULD provide mitigations for the Slowloris
attacks, such as increasing the maximum number of clients the server attacks, such as increasing the maximum number of clients the server
will allow, limiting the number of connections a single IP address is will allow, limiting the number of connections a single IP address is
allowed to make, imposing restrictions on the minimum transfer speed allowed to make, imposing restrictions on the minimum transfer speed
a connection is allowed to have, and restricting the length of time a connection is allowed to have, and restricting the length of time
an endpoint is allowed to stay connected. an endpoint is allowed to stay connected.
12.5. Stream Fragmentation and Reassembly Attacks 12.5. Stream Fragmentation and Reassembly Attacks
An adversarial endpoint might intentionally fragment the data on An adversarial sender might intentionally send fragments of stream
stream buffers in order to cause disproportionate memory commitment. data in order to cause disproportionate receive buffer memory
An adversarial endpoint could open a stream and send some STREAM commitment and/or creation of a large and inefficient data structure.
frames containing arbitrary fragments of the stream content.
The attack is mitigated if flow control windows correspond to An adversarial receiver might intentionally not acknowledge packets
available memory. However, some receivers will over-commit memory containing stream data in order to force the sender to store the
and advertise flow control offsets in the aggregate that exceed unacknowledged stream data for retransmission.
actual available memory. The over-commitment strategy can lead to
better performance when endpoints are well behaved, but renders
endpoints vulnerable to the stream fragmentation attack.
QUIC deployments SHOULD provide mitigations against the stream The attack on receivers is mitigated if flow control windows
fragmentation attack. Mitigations could consist of avoiding over- correspond to available memory. However, some receivers will over-
committing memory, delaying reassembly of STREAM frames, implementing commit memory and advertise flow control offsets in the aggregate
heuristics based on the age and duration of reassembly holes, or some that exceed actual available memory. The over-commitment strategy
combination. can lead to better performance when endpoints are well behaved, but
renders endpoints vulnerable to the stream fragmentation attack.
QUIC deployments SHOULD provide mitigations against stream
fragmentation attacks. Mitigations could consist of avoiding over-
committing memory, limiting the size of tracking data structures,
delaying reassembly of STREAM frames, implementing heuristics based
on the age and duration of reassembly holes, or some combination.
12.6. Stream Commitment Attack 12.6. Stream Commitment Attack
An adversarial endpoint can open lots of streams, exhausting state on An adversarial endpoint can open lots of streams, exhausting state on
an endpoint. The adversarial endpoint could repeat the process on a an endpoint. The adversarial endpoint could repeat the process on a
large number of connections, in a manner similar to SYN flooding large number of connections, in a manner similar to SYN flooding
attacks in TCP. attacks in TCP.
Normally, clients will open streams sequentially, as explained in Normally, clients will open streams sequentially, as explained in
Section 9.1. However, when several streams are initiated at short Section 9.1. However, when several streams are initiated at short
skipping to change at page 112, line 33 skipping to change at page 116, line 31
| | | | | | | |
| 0x0007 | ack_delay_exponent | Section 6.6.1 | | 0x0007 | ack_delay_exponent | Section 6.6.1 |
| | | | | | | |
| 0x0008 | initial_max_uni_streams | Section 6.6.1 | | 0x0008 | initial_max_uni_streams | Section 6.6.1 |
| | | | | | | |
| 0x0009 | disable_migration | Section 6.6.1 | | 0x0009 | disable_migration | Section 6.6.1 |
| | | | | | | |
| 0x000a | initial_max_stream_data_bidi_remote | Section 6.6.1 | | 0x000a | initial_max_stream_data_bidi_remote | Section 6.6.1 |
| | | | | | | |
| 0x000b | initial_max_stream_data_uni | Section 6.6.1 | | 0x000b | initial_max_stream_data_uni | Section 6.6.1 |
| | | |
| 0x000c | max_ack_delay | Section 6.6.1 |
| | | |
| 0x000d | original_connection_id | Section 6.6.1 |
+--------+-------------------------------------+---------------+ +--------+-------------------------------------+---------------+
Table 7: Initial QUIC Transport Parameters Entries Table 7: Initial QUIC Transport Parameters Entries
13.2. QUIC Frame Type Registry 13.2. QUIC Frame Type Registry
IANA [SHALL add/has added] a registry for "QUIC Frame Types" under a IANA [SHALL add/has added] a registry for "QUIC Frame Types" under a
"QUIC Protocol" heading. "QUIC Protocol" heading.
The "QUIC Frame Types" registry governs a 62-bit space. This space The "QUIC Frame Types" registry governs a 62-bit space. This space
skipping to change at page 115, line 24 skipping to change at page 120, line 24
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-14 (work and Congestion Control", draft-ietf-quic-recovery-15 (work
in progress), August 2018. in progress), October 2018.
[QUIC-TLS] [QUIC-TLS]
Thomson, M., Ed. and S. Turner, Ed., "Using Transport Thomson, M., Ed. and S. Turner, Ed., "Using Transport
Layer Security (TLS) to Secure QUIC", draft-ietf-quic- Layer Security (TLS) to Secure QUIC", draft-ietf-quic-
tls-14 (work in progress), August 2018. tls-15 (work in progress), October 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
of Explicit Congestion Notification (ECN) to IP", of Explicit Congestion Notification (ECN) to IP",
RFC 3168, DOI 10.17487/RFC3168, September 2001, RFC 3168, DOI 10.17487/RFC3168, September 2001,
<https://www.rfc-editor.org/info/rfc3168>. <https://www.rfc-editor.org/info/rfc3168>.
skipping to change at page 116, line 36 skipping to change at page 121, line 36
Roskind, J., "QUIC: Multiplexed Transport Over UDP", Roskind, J., "QUIC: Multiplexed Transport Over UDP",
December 2013, <https://goo.gl/dMVtFi>. December 2013, <https://goo.gl/dMVtFi>.
[HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext [HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540, Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015, DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>. <https://www.rfc-editor.org/info/rfc7540>.
[QUIC-INVARIANTS] [QUIC-INVARIANTS]
Thomson, M., "Version-Independent Properties of QUIC", Thomson, M., "Version-Independent Properties of QUIC",
draft-ietf-quic-invariants-01 (work in progress), August draft-ietf-quic-invariants-03 (work in progress), October
2018. 2018.
[RFC2018] Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP [RFC2018] Mathis, M., Mahdavi, J., Floyd, S., and A. Romanow, "TCP
Selective Acknowledgment Options", RFC 2018, Selective Acknowledgment Options", RFC 2018,
DOI 10.17487/RFC2018, October 1996, DOI 10.17487/RFC2018, October 1996,
<https://www.rfc-editor.org/info/rfc2018>. <https://www.rfc-editor.org/info/rfc2018>.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104, Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997, DOI 10.17487/RFC2104, February 1997,
skipping to change at page 118, line 37 skipping to change at page 123, line 37
return candidate_pn - pn_win return candidate_pn - pn_win
return candidate_pn return candidate_pn
Appendix B. Change Log Appendix B. 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.
B.1. Since draft-ietf-quic-transport-13 B.1. Since draft-ietf-quic-transport-14
o Merge ACK and ACK_ECN (#1778, #1801)
o Explicitly communicate max_ack_delay (#981, #1781)
o Validate original connection ID after Retry packets (#1710, #1486,
#1793)
o Idle timeout is optional and has no specified maximum (#1520,
#1521)
o Update connection ID handling; add RETIRE_CONNECTION_ID type
(#1464, #1468, #1483, #1484, #1486, #1495, #1729, #1742, #1799,
#1821)
o Include a Token in all Initial packets (#1649, #1794)
o Prevent handshake deadlock (#1764, #1824)
B.2. Since draft-ietf-quic-transport-13
o Streams open when higher-numbered streams of the same type open o Streams open when higher-numbered streams of the same type open
(#1342, #1549) (#1342, #1549)
o Split initial stream flow control limit into 3 transport o Split initial stream flow control limit into 3 transport
parameters (#1016, #1542) parameters (#1016, #1542)
o All flow control transport parameters are optional (#1610) o All flow control transport parameters are optional (#1610)
o Removed UNSOLICITED_PATH_RESPONSE error code (#1265, #1539) o Removed UNSOLICITED_PATH_RESPONSE error code (#1265, #1539)
skipping to change at page 119, line 26 skipping to change at page 124, line 47
o Permit 0-RTT after receiving Version Negotiation or Retry (#1507, o Permit 0-RTT after receiving Version Negotiation or Retry (#1507,
#1514, #1621) #1514, #1621)
o Permit Retry in response to 0-RTT (#1547, #1552) o Permit Retry in response to 0-RTT (#1547, #1552)
o Looser verification of ECN counters to account for ACK loss o Looser verification of ECN counters to account for ACK loss
(#1555, #1481, #1565) (#1555, #1481, #1565)
o Remove frame type field from APPLICATION_CLOSE (#1508, #1528) o Remove frame type field from APPLICATION_CLOSE (#1508, #1528)
B.2. Since draft-ietf-quic-transport-12 B.3. Since draft-ietf-quic-transport-12
o Changes to integration of the TLS handshake (#829, #1018, #1094, o Changes to integration of the TLS handshake (#829, #1018, #1094,
#1165, #1190, #1233, #1242, #1252, #1450, #1458) #1165, #1190, #1233, #1242, #1252, #1450, #1458)
* The cryptographic handshake uses CRYPTO frames, not stream 0 * The cryptographic handshake uses CRYPTO frames, not stream 0
* QUIC packet protection is used in place of TLS record * QUIC packet protection is used in place of TLS record
protection protection
* Separate QUIC packet number spaces are used for the handshake * Separate QUIC packet number spaces are used for the handshake
* Changed Retry to be independent of the cryptographic handshake * Changed Retry to be independent of the cryptographic handshake
* Added NEW_TOKEN frame and Token fields to Initial packet * Added NEW_TOKEN frame and Token fields to Initial packet
* Limit the use of HelloRetryRequest to address TLS needs (like * Limit the use of HelloRetryRequest to address TLS needs (like
skipping to change at page 120, line 20 skipping to change at page 125, line 40
o Fixed sampling method for packet number encryption; the length o Fixed sampling method for packet number encryption; the length
field in long headers includes the packet number field in addition field in long headers includes the packet number field in addition
to the packet payload (#1387, #1389) to the packet payload (#1387, #1389)
o Stateless Reset is now symmetric and subject to size constraints o Stateless Reset is now symmetric and subject to size constraints
(#466, #1346) (#466, #1346)
o Added frame type extension mechanism (#58, #1473) o Added frame type extension mechanism (#58, #1473)
B.3. Since draft-ietf-quic-transport-11 B.4. Since draft-ietf-quic-transport-11
o Enable server to transition connections to a preferred address o Enable server to transition connections to a preferred address
(#560, #1251) (#560, #1251)
o Packet numbers are encrypted (#1174, #1043, #1048, #1034, #850, o Packet numbers are encrypted (#1174, #1043, #1048, #1034, #850,
#990, #734, #1317, #1267, #1079) #990, #734, #1317, #1267, #1079)
o Packet numbers use a variable-length encoding (#989, #1334) o Packet numbers use a variable-length encoding (#989, #1334)
o STREAM frames can now be empty (#1350) o STREAM frames can now be empty (#1350)
B.4. Since draft-ietf-quic-transport-10 B.5. Since draft-ietf-quic-transport-10
o Swap payload length and packed number fields in long header o Swap payload length and packed number fields in long header
(#1294) (#1294)
o Clarified that CONNECTION_CLOSE is allowed in Handshake packet o Clarified that CONNECTION_CLOSE is allowed in Handshake packet
(#1274) (#1274)
o Spin bit reserved (#1283) o Spin bit reserved (#1283)
o Coalescing multiple QUIC packets in a UDP datagram (#1262, #1285) o Coalescing multiple QUIC packets in a UDP datagram (#1262, #1285)
skipping to change at page 121, line 4 skipping to change at page 126, line 24
o Coalescing multiple QUIC packets in a UDP datagram (#1262, #1285) o Coalescing multiple QUIC packets in a UDP datagram (#1262, #1285)
o A more complete connection migration (#1249) o A more complete connection migration (#1249)
o Refine opportunistic ACK defense text (#305, #1030, #1185) o Refine opportunistic ACK defense text (#305, #1030, #1185)
o A Stateless Reset Token isn't mandatory (#818, #1191) o A Stateless Reset Token isn't mandatory (#818, #1191)
o Removed implicit stream opening (#896, #1193) o Removed implicit stream opening (#896, #1193)
o An empty STREAM frame can be used to open a stream without sending o An empty STREAM frame can be used to open a stream without sending
data (#901, #1194) data (#901, #1194)
o Define stream counts in transport parameters rather than a maximum o Define stream counts in transport parameters rather than a maximum
stream ID (#1023, #1065) stream ID (#1023, #1065)
o STOP_SENDING is now prohibited before streams are used (#1050) o STOP_SENDING is now prohibited before streams are used (#1050)
o Recommend including ACK in Retry packets and allow PADDING (#1067, o Recommend including ACK in Retry packets and allow PADDING (#1067,
#882) #882)
o Endpoints now become closing after an idle timeout (#1178, #1179) o Endpoints now become closing after an idle timeout (#1178, #1179)
o Remove implication that Version Negotiation is sent when a packet o Remove implication that Version Negotiation is sent when a packet
of the wrong version is received (#1197) of the wrong version is received (#1197)
B.5. Since draft-ietf-quic-transport-09 B.6. Since draft-ietf-quic-transport-09
o Added PATH_CHALLENGE and PATH_RESPONSE frames to replace PING with o Added PATH_CHALLENGE and PATH_RESPONSE frames to replace PING with
Data and PONG frame. Changed ACK frame type from 0x0e to 0x0d. Data and PONG frame. Changed ACK frame type from 0x0e to 0x0d.
(#1091, #725, #1086) (#1091, #725, #1086)
o A server can now only send 3 packets without validating the client o A server can now only send 3 packets without validating the client
address (#38, #1090) address (#38, #1090)
o Delivery order of stream data is no longer strongly specified o Delivery order of stream data is no longer strongly specified
(#252, #1070) (#252, #1070)
skipping to change at page 121, line 47 skipping to change at page 127, line 20
o Improved retransmission rules for all frame types: information is o Improved retransmission rules for all frame types: information is
retransmitted, not packets or frames (#463, #765, #1095, #1053) retransmitted, not packets or frames (#463, #765, #1095, #1053)
o Added an error code for server busy signals (#1137) o Added an error code for server busy signals (#1137)
o Endpoints now set the connection ID that their peer uses. o Endpoints now set the connection ID that their peer uses.
Connection IDs are variable length. Removed the Connection IDs are variable length. Removed the
omit_connection_id transport parameter and the corresponding short omit_connection_id transport parameter and the corresponding short
header flag. (#1089, #1052, #1146, #821, #745, #821, #1166, #1151) header flag. (#1089, #1052, #1146, #821, #745, #821, #1166, #1151)
B.6. Since draft-ietf-quic-transport-08 B.7. Since draft-ietf-quic-transport-08
o Clarified requirements for BLOCKED usage (#65, #924) o Clarified requirements for BLOCKED usage (#65, #924)
o BLOCKED frame now includes reason for blocking (#452, #924, #927, o BLOCKED frame now includes reason for blocking (#452, #924, #927,
#928) #928)
o GAP limitation in ACK Frame (#613) o GAP limitation in ACK Frame (#613)
o Improved PMTUD description (#614, #1036) o Improved PMTUD description (#614, #1036)
o Clarified stream state machine (#634, #662, #743, #894) o Clarified stream state machine (#634, #662, #743, #894)
o Reserved versions don't need to be generated deterministically o Reserved versions don't need to be generated deterministically
skipping to change at page 122, line 28 skipping to change at page 127, line 48
o Stateless reset clarified as version-specific (#930, #986) o Stateless reset clarified as version-specific (#930, #986)
o initial_max_stream_id_x transport parameters are optional (#970, o initial_max_stream_id_x transport parameters are optional (#970,
#971) #971)
o Ack Delay assumes a default value during the handshake (#1007, o Ack Delay assumes a default value during the handshake (#1007,
#1009) #1009)
o Removed transport parameters from NewSessionTicket (#1015) o Removed transport parameters from NewSessionTicket (#1015)
B.7. Since draft-ietf-quic-transport-07 B.8. Since draft-ietf-quic-transport-07
o The long header now has version before packet number (#926, #939) o The long header now has version before packet number (#926, #939)
o Rename and consolidate packet types (#846, #822, #847) o Rename and consolidate packet types (#846, #822, #847)
o Packet types are assigned new codepoints and the Connection ID o Packet types are assigned new codepoints and the Connection ID
Flag is inverted (#426, #956) Flag is inverted (#426, #956)
o Removed type for Version Negotiation and use Version 0 (#963, o Removed type for Version Negotiation and use Version 0 (#963,
#968) #968)
o Streams are split into unidirectional and bidirectional (#643, o Streams are split into unidirectional and bidirectional (#643,
#656, #720, #872, #175, #885) #656, #720, #872, #175, #885)
* Stream limits now have separate uni- and bi-directional * Stream limits now have separate uni- and bi-directional
skipping to change at page 123, line 25 skipping to change at page 128, line 42
o Address validation for connection migration (#161, #732, #878) o Address validation for connection migration (#161, #732, #878)
o Clearly defined retransmission rules for BLOCKED (#452, #65, #924) o Clearly defined retransmission rules for BLOCKED (#452, #65, #924)
o negotiated_version is sent in server transport parameters (#710, o negotiated_version is sent in server transport parameters (#710,
#959) #959)
o Increased the range over which packet numbers are randomized o Increased the range over which packet numbers are randomized
(#864, #850, #964) (#864, #850, #964)
B.8. Since draft-ietf-quic-transport-06 B.9. Since draft-ietf-quic-transport-06
o Replaced FNV-1a with AES-GCM for all "Cleartext" packets (#554) o Replaced FNV-1a with AES-GCM for all "Cleartext" packets (#554)
o Split error code space between application and transport (#485) o Split error code space between application and transport (#485)
o Stateless reset token moved to end (#820) o Stateless reset token moved to end (#820)
o 1-RTT-protected long header types removed (#848) o 1-RTT-protected long header types removed (#848)
o No acknowledgments during draining period (#852) o No acknowledgments during draining period (#852)
o Remove "application close" as a separate close type (#854) o Remove "application close" as a separate close type (#854)
o Remove timestamps from the ACK frame (#841) o Remove timestamps from the ACK frame (#841)
o Require transport parameters to only appear once (#792) o Require transport parameters to only appear once (#792)
B.9. Since draft-ietf-quic-transport-05 B.10. 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)
B.10. Since draft-ietf-quic-transport-04 B.11. Since draft-ietf-quic-transport-04
o Introduce STOP_SENDING frame, RST_STREAM only resets in one o Introduce STOP_SENDING frame, RST_STREAM only resets in one
direction (#165) direction (#165)
o Removed GOAWAY; application protocols are responsible for graceful o Removed GOAWAY; application protocols are responsible for graceful
shutdown (#696) shutdown (#696)
o Reduced the number of error codes (#96, #177, #184, #211) o Reduced the number of error codes (#96, #177, #184, #211)
o Version validation fields can't move or change (#121) o Version validation fields can't move or change (#121)
skipping to change at page 124, line 31 skipping to change at page 130, line 4
NewSessionTicket message (#547) NewSessionTicket message (#547)
o Clarify the meaning of "bytes in flight" (#550) o Clarify the meaning of "bytes in flight" (#550)
o Public reset is now stateless reset and not visible to the path o Public reset is now stateless reset and not visible to the path
(#215) (#215)
o Reordered bits and fields in STREAM frame (#620) o Reordered bits and fields in STREAM frame (#620)
o Clarifications to the stream state machine (#572, #571) o Clarifications to the stream state machine (#572, #571)
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)
B.11. Since draft-ietf-quic-transport-03 B.12. 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
B.12. Since draft-ietf-quic-transport-02 B.13. Since draft-ietf-quic-transport-02
o The size of the initial packet payload has a fixed minimum (#267, o The size of the initial packet payload has a fixed minimum (#267,
#472) #472)
o Define when Version Negotiation packets are ignored (#284, #294, o Define when Version Negotiation packets are ignored (#284, #294,
#241, #143, #474) #241, #143, #474)
o The 64-bit FNV-1a algorithm is used for integrity protection of o The 64-bit FNV-1a algorithm is used for integrity protection of
unprotected packets (#167, #480, #481, #517) unprotected packets (#167, #480, #481, #517)
skipping to change at page 125, line 37 skipping to change at page 131, line 4
different handshake protocol (#516) different handshake protocol (#516)
o STREAM frames have a reduced number of offset lengths (#543, #430) o STREAM frames have a reduced number of offset lengths (#543, #430)
o Split some frames into separate connection- and stream- level o Split some frames into separate connection- and stream- level
frames (#443) frames (#443)
* WINDOW_UPDATE split into MAX_DATA and MAX_STREAM_DATA (#450) * WINDOW_UPDATE split into MAX_DATA and MAX_STREAM_DATA (#450)
* BLOCKED split to match WINDOW_UPDATE split (#454) * BLOCKED split to match WINDOW_UPDATE split (#454)
* Define STREAM_ID_NEEDED frame (#455) * Define STREAM_ID_NEEDED frame (#455)
o A NEW_CONNECTION_ID frame supports connection migration without o A NEW_CONNECTION_ID frame supports connection migration without
linkability (#232, #491, #496) linkability (#232, #491, #496)
o Transport parameters for 0-RTT are retained from a previous o Transport parameters for 0-RTT are retained from a previous
connection (#405, #513, #512) connection (#405, #513, #512)
* A client in 0-RTT no longer required to reset excess streams * A client in 0-RTT no longer required to reset excess streams
(#425, #479) (#425, #479)
o Expanded security considerations (#440, #444, #445, #448) o Expanded security considerations (#440, #444, #445, #448)
B.13. Since draft-ietf-quic-transport-01 B.14. Since draft-ietf-quic-transport-01
o Defined short and long packet headers (#40, #148, #361) o Defined short and long packet headers (#40, #148, #361)
o Defined a versioning scheme and stable fields (#51, #361) o Defined a versioning scheme and stable fields (#51, #361)
o Define reserved version values for "greasing" negotiation (#112, o Define reserved version values for "greasing" negotiation (#112,
#278) #278)
o The initial packet number is randomized (#35, #283) o The initial packet number is randomized (#35, #283)
skipping to change at page 128, line 5 skipping to change at page 133, line 17
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)
B.14. Since draft-ietf-quic-transport-00 B.15. 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
B.15. Since draft-hamilton-quic-transport-protocol-01 B.16. Since draft-hamilton-quic-transport-protocol-01
o Adopted as base for draft-ietf-quic-tls o Adopted as base for draft-ietf-quic-tls
o Updated authors/editors list o Updated authors/editors list
o Added IANA Considerations section o Added IANA Considerations section
o Moved Contributors and Acknowledgments to appendices o Moved Contributors and Acknowledgments to appendices
Acknowledgments Acknowledgments
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