draft-ietf-quic-http-33.txt   draft-ietf-quic-http-latest.txt 
QUIC Working Group M. Bishop, Ed. QUIC Working Group M. Bishop, Ed.
Internet-Draft Akamai Internet-Draft Akamai
Intended status: Standards Track December 15, 2020 Intended status: Standards Track January 27, 2021
Expires: June 18, 2021 Expires: July 31, 2021
Hypertext Transfer Protocol Version 3 (HTTP/3) Hypertext Transfer Protocol Version 3 (HTTP/3)
draft-ietf-quic-http-33 draft-ietf-quic-http-latest
Abstract Abstract
The QUIC transport protocol has several features that are desirable The QUIC transport protocol has several features that are desirable
in a transport for HTTP, such as stream multiplexing, per-stream flow in a transport for HTTP, such as stream multiplexing, per-stream flow
control, and low-latency connection establishment. This document control, and low-latency connection establishment. This document
describes a mapping of HTTP semantics over QUIC. This document also describes a mapping of HTTP semantics over QUIC. This document also
identifies HTTP/2 features that are subsumed by QUIC, and describes identifies HTTP/2 features that are subsumed by QUIC, and describes
how HTTP/2 extensions can be ported to HTTP/3. how HTTP/2 extensions can be ported to HTTP/3.
skipping to change at page 2, line 4 skipping to change at page 2, line 4
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Prior versions of HTTP . . . . . . . . . . . . . . . . . 5 1.1. Prior versions of HTTP . . . . . . . . . . . . . . . . . 5
1.2. Delegation to QUIC . . . . . . . . . . . . . . . . . . . 5 1.2. Delegation to QUIC . . . . . . . . . . . . . . . . . . . 5
2. HTTP/3 Protocol Overview . . . . . . . . . . . . . . . . . . 5 2. HTTP/3 Protocol Overview . . . . . . . . . . . . . . . . . . 6
2.1. Document Organization . . . . . . . . . . . . . . . . . . 6 2.1. Document Organization . . . . . . . . . . . . . . . . . . 6
2.2. Conventions and Terminology . . . . . . . . . . . . . . . 7 2.2. Conventions and Terminology . . . . . . . . . . . . . . . 7
3. Connection Setup and Management . . . . . . . . . . . . . . . 8 3. Connection Setup and Management . . . . . . . . . . . . . . . 8
3.1. Discovering an HTTP/3 Endpoint . . . . . . . . . . . . . 8 3.1. Discovering an HTTP/3 Endpoint . . . . . . . . . . . . . 9
3.1.1. HTTP Alternative Services . . . . . . . . . . . . . . 9 3.1.1. HTTP Alternative Services . . . . . . . . . . . . . . 9
3.1.2. Other Schemes . . . . . . . . . . . . . . . . . . . . 10 3.1.2. Other Schemes . . . . . . . . . . . . . . . . . . . . 10
3.2. Connection Establishment . . . . . . . . . . . . . . . . 10 3.2. Connection Establishment . . . . . . . . . . . . . . . . 10
3.3. Connection Reuse . . . . . . . . . . . . . . . . . . . . 11 3.3. Connection Reuse . . . . . . . . . . . . . . . . . . . . 11
4. HTTP Request Lifecycle . . . . . . . . . . . . . . . . . . . 11 4. HTTP Request Lifecycle . . . . . . . . . . . . . . . . . . . 12
4.1. HTTP Message Exchanges . . . . . . . . . . . . . . . . . 11 4.1. HTTP Message Exchanges . . . . . . . . . . . . . . . . . 12
4.1.1. Field Formatting and Compression . . . . . . . . . . 13 4.1.1. Field Formatting and Compression . . . . . . . . . . 14
4.1.2. Request Cancellation and Rejection . . . . . . . . . 17 4.1.2. Request Cancellation and Rejection . . . . . . . . . 17
4.1.3. Malformed Requests and Responses . . . . . . . . . . 18 4.1.3. Malformed Requests and Responses . . . . . . . . . . 18
4.2. The CONNECT Method . . . . . . . . . . . . . . . . . . . 19 4.2. The CONNECT Method . . . . . . . . . . . . . . . . . . . 19
4.3. HTTP Upgrade . . . . . . . . . . . . . . . . . . . . . . 20 4.3. HTTP Upgrade . . . . . . . . . . . . . . . . . . . . . . 20
4.4. Server Push . . . . . . . . . . . . . . . . . . . . . . . 20 4.4. Server Push . . . . . . . . . . . . . . . . . . . . . . . 21
5. Connection Closure . . . . . . . . . . . . . . . . . . . . . 22 5. Connection Closure . . . . . . . . . . . . . . . . . . . . . 23
5.1. Idle Connections . . . . . . . . . . . . . . . . . . . . 22 5.1. Idle Connections . . . . . . . . . . . . . . . . . . . . 23
5.2. Connection Shutdown . . . . . . . . . . . . . . . . . . . 23 5.2. Connection Shutdown . . . . . . . . . . . . . . . . . . . 23
5.3. Immediate Application Closure . . . . . . . . . . . . . . 25 5.3. Immediate Application Closure . . . . . . . . . . . . . . 25
5.4. Transport Closure . . . . . . . . . . . . . . . . . . . . 25 5.4. Transport Closure . . . . . . . . . . . . . . . . . . . . 26
6. Stream Mapping and Usage . . . . . . . . . . . . . . . . . . 25 6. Stream Mapping and Usage . . . . . . . . . . . . . . . . . . 26
6.1. Bidirectional Streams . . . . . . . . . . . . . . . . . . 26 6.1. Bidirectional Streams . . . . . . . . . . . . . . . . . . 26
6.2. Unidirectional Streams . . . . . . . . . . . . . . . . . 26 6.2. Unidirectional Streams . . . . . . . . . . . . . . . . . 27
6.2.1. Control Streams . . . . . . . . . . . . . . . . . . . 27 6.2.1. Control Streams . . . . . . . . . . . . . . . . . . . 28
6.2.2. Push Streams . . . . . . . . . . . . . . . . . . . . 28 6.2.2. Push Streams . . . . . . . . . . . . . . . . . . . . 29
6.2.3. Reserved Stream Types . . . . . . . . . . . . . . . . 28 6.2.3. Reserved Stream Types . . . . . . . . . . . . . . . . 29
7. HTTP Framing Layer . . . . . . . . . . . . . . . . . . . . . 29 7. HTTP Framing Layer . . . . . . . . . . . . . . . . . . . . . 30
7.1. Frame Layout . . . . . . . . . . . . . . . . . . . . . . 30 7.1. Frame Layout . . . . . . . . . . . . . . . . . . . . . . 31
7.2. Frame Definitions . . . . . . . . . . . . . . . . . . . . 30 7.2. Frame Definitions . . . . . . . . . . . . . . . . . . . . 31
7.2.1. DATA . . . . . . . . . . . . . . . . . . . . . . . . 30 7.2.1. DATA . . . . . . . . . . . . . . . . . . . . . . . . 32
7.2.2. HEADERS . . . . . . . . . . . . . . . . . . . . . . . 31 7.2.2. HEADERS . . . . . . . . . . . . . . . . . . . . . . . 32
7.2.3. CANCEL_PUSH . . . . . . . . . . . . . . . . . . . . . 31 7.2.3. CANCEL_PUSH . . . . . . . . . . . . . . . . . . . . . 32
7.2.4. SETTINGS . . . . . . . . . . . . . . . . . . . . . . 32 7.2.4. SETTINGS . . . . . . . . . . . . . . . . . . . . . . 34
7.2.5. PUSH_PROMISE . . . . . . . . . . . . . . . . . . . . 35 7.2.5. PUSH_PROMISE . . . . . . . . . . . . . . . . . . . . 37
7.2.6. GOAWAY . . . . . . . . . . . . . . . . . . . . . . . 37 7.2.6. GOAWAY . . . . . . . . . . . . . . . . . . . . . . . 38
7.2.7. MAX_PUSH_ID . . . . . . . . . . . . . . . . . . . . . 37 7.2.7. MAX_PUSH_ID . . . . . . . . . . . . . . . . . . . . . 39
7.2.8. Reserved Frame Types . . . . . . . . . . . . . . . . 38 7.2.8. Reserved Frame Types . . . . . . . . . . . . . . . . 39
8. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 39 8. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 40
8.1. HTTP/3 Error Codes . . . . . . . . . . . . . . . . . . . 39 8.1. HTTP/3 Error Codes . . . . . . . . . . . . . . . . . . . 41
9. Extensions to HTTP/3 . . . . . . . . . . . . . . . . . . . . 41 9. Extensions to HTTP/3 . . . . . . . . . . . . . . . . . . . . 42
10. Security Considerations . . . . . . . . . . . . . . . . . . . 42 10. Security Considerations . . . . . . . . . . . . . . . . . . . 43
10.1. Server Authority . . . . . . . . . . . . . . . . . . . . 42 10.1. Server Authority . . . . . . . . . . . . . . . . . . . . 43
10.2. Cross-Protocol Attacks . . . . . . . . . . . . . . . . . 42 10.2. Cross-Protocol Attacks . . . . . . . . . . . . . . . . . 43
10.3. Intermediary Encapsulation Attacks . . . . . . . . . . . 42 10.3. Intermediary Encapsulation Attacks . . . . . . . . . . . 43
10.4. Cacheability of Pushed Responses . . . . . . . . . . . . 43 10.4. Cacheability of Pushed Responses . . . . . . . . . . . . 44
10.5. Denial-of-Service Considerations . . . . . . . . . . . . 43 10.5. Denial-of-Service Considerations . . . . . . . . . . . . 44
10.5.1. Limits on Field Section Size . . . . . . . . . . . . 44 10.5.1. Limits on Field Section Size . . . . . . . . . . . . 45
10.5.2. CONNECT Issues . . . . . . . . . . . . . . . . . . . 44 10.5.2. CONNECT Issues . . . . . . . . . . . . . . . . . . . 46
10.6. Use of Compression . . . . . . . . . . . . . . . . . . . 45 10.6. Use of Compression . . . . . . . . . . . . . . . . . . . 46
10.7. Padding and Traffic Analysis . . . . . . . . . . . . . . 45 10.7. Padding and Traffic Analysis . . . . . . . . . . . . . . 46
10.8. Frame Parsing . . . . . . . . . . . . . . . . . . . . . 46 10.8. Frame Parsing . . . . . . . . . . . . . . . . . . . . . 47
10.9. Early Data . . . . . . . . . . . . . . . . . . . . . . . 46 10.9. Early Data . . . . . . . . . . . . . . . . . . . . . . . 47
10.10. Migration . . . . . . . . . . . . . . . . . . . . . . . 46 10.10. Migration . . . . . . . . . . . . . . . . . . . . . . . 48
10.11. Privacy Considerations . . . . . . . . . . . . . . . . . 46 10.11. Privacy Considerations . . . . . . . . . . . . . . . . . 48
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 47 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 48
11.1. Registration of HTTP/3 Identification String . . . . . . 47 11.1. Registration of HTTP/3 Identification String . . . . . . 48
11.2. New Registries . . . . . . . . . . . . . . . . . . . . . 47 11.2. New Registries . . . . . . . . . . . . . . . . . . . . . 49
11.2.1. Frame Types . . . . . . . . . . . . . . . . . . . . 47 11.2.1. Frame Types . . . . . . . . . . . . . . . . . . . . 49
11.2.2. Settings Parameters . . . . . . . . . . . . . . . . 49 11.2.2. Settings Parameters . . . . . . . . . . . . . . . . 50
11.2.3. Error Codes . . . . . . . . . . . . . . . . . . . . 50 11.2.3. Error Codes . . . . . . . . . . . . . . . . . . . . 51
11.2.4. Stream Types . . . . . . . . . . . . . . . . . . . . 53 11.2.4. Stream Types . . . . . . . . . . . . . . . . . . . . 54
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 53 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 54
12.1. Normative References . . . . . . . . . . . . . . . . . . 53 12.1. Normative References . . . . . . . . . . . . . . . . . . 54
12.2. Informative References . . . . . . . . . . . . . . . . . 55 12.2. Informative References . . . . . . . . . . . . . . . . . 56
Appendix A. Considerations for Transitioning from HTTP/2 . . . . 56 Appendix A. Considerations for Transitioning from HTTP/2 . . . . 57
A.1. Streams . . . . . . . . . . . . . . . . . . . . . . . . . 56 A.1. Streams . . . . . . . . . . . . . . . . . . . . . . . . . 57
A.2. HTTP Frame Types . . . . . . . . . . . . . . . . . . . . 57 A.2. HTTP Frame Types . . . . . . . . . . . . . . . . . . . . 58
A.2.1. Prioritization Differences . . . . . . . . . . . . . 57 A.2.1. Prioritization Differences . . . . . . . . . . . . . 58
A.2.2. Field Compression Differences . . . . . . . . . . . . 57 A.2.2. Field Compression Differences . . . . . . . . . . . . 59
A.2.3. Flow Control Differences . . . . . . . . . . . . . . 58 A.2.3. Flow Control Differences . . . . . . . . . . . . . . 59
A.2.4. Guidance for New Frame Type Definitions . . . . . . . 58 A.2.4. Guidance for New Frame Type Definitions . . . . . . . 59
A.2.5. Mapping Between HTTP/2 and HTTP/3 Frame Types . . . . 58 A.2.5. Comparison Between HTTP/2 and HTTP/3 Frame Types . . 60
A.3. HTTP/2 SETTINGS Parameters . . . . . . . . . . . . . . . 59 A.3. HTTP/2 SETTINGS Parameters . . . . . . . . . . . . . . . 61
A.4. HTTP/2 Error Codes . . . . . . . . . . . . . . . . . . . 61 A.4. HTTP/2 Error Codes . . . . . . . . . . . . . . . . . . . 62
A.4.1. Mapping Between HTTP/2 and HTTP/3 Errors . . . . . . 62 A.4.1. Mapping Between HTTP/2 and HTTP/3 Errors . . . . . . 63
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 62 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 64
B.1. Since draft-ietf-quic-http-32 . . . . . . . . . . . . . . 63 B.1. Since draft-ietf-quic-http-32 . . . . . . . . . . . . . . 64
B.2. Since draft-ietf-quic-http-31 . . . . . . . . . . . . . . 63 B.2. Since draft-ietf-quic-http-31 . . . . . . . . . . . . . . 64
B.3. Since draft-ietf-quic-http-30 . . . . . . . . . . . . . . 63 B.3. Since draft-ietf-quic-http-30 . . . . . . . . . . . . . . 64
B.4. Since draft-ietf-quic-http-29 . . . . . . . . . . . . . . 63 B.4. Since draft-ietf-quic-http-29 . . . . . . . . . . . . . . 64
B.5. Since draft-ietf-quic-http-28 . . . . . . . . . . . . . . 63 B.5. Since draft-ietf-quic-http-28 . . . . . . . . . . . . . . 64
B.6. Since draft-ietf-quic-http-27 . . . . . . . . . . . . . . 63 B.6. Since draft-ietf-quic-http-27 . . . . . . . . . . . . . . 64
B.7. Since draft-ietf-quic-http-26 . . . . . . . . . . . . . . 63 B.7. Since draft-ietf-quic-http-26 . . . . . . . . . . . . . . 65
B.8. Since draft-ietf-quic-http-25 . . . . . . . . . . . . . . 64 B.8. Since draft-ietf-quic-http-25 . . . . . . . . . . . . . . 65
B.9. Since draft-ietf-quic-http-24 . . . . . . . . . . . . . . 64 B.9. Since draft-ietf-quic-http-24 . . . . . . . . . . . . . . 65
B.10. Since draft-ietf-quic-http-23 . . . . . . . . . . . . . . 64 B.10. Since draft-ietf-quic-http-23 . . . . . . . . . . . . . . 65
B.11. Since draft-ietf-quic-http-22 . . . . . . . . . . . . . . 64 B.11. Since draft-ietf-quic-http-22 . . . . . . . . . . . . . . 65
B.12. Since draft-ietf-quic-http-21 . . . . . . . . . . . . . . 65 B.12. Since draft-ietf-quic-http-21 . . . . . . . . . . . . . . 66
B.13. Since draft-ietf-quic-http-20 . . . . . . . . . . . . . . 65 B.13. Since draft-ietf-quic-http-20 . . . . . . . . . . . . . . 66
B.14. Since draft-ietf-quic-http-19 . . . . . . . . . . . . . . 66 B.14. Since draft-ietf-quic-http-19 . . . . . . . . . . . . . . 67
B.15. Since draft-ietf-quic-http-18 . . . . . . . . . . . . . . 66 B.15. Since draft-ietf-quic-http-18 . . . . . . . . . . . . . . 67
B.16. Since draft-ietf-quic-http-17 . . . . . . . . . . . . . . 67 B.16. Since draft-ietf-quic-http-17 . . . . . . . . . . . . . . 68
B.17. Since draft-ietf-quic-http-16 . . . . . . . . . . . . . . 67 B.17. Since draft-ietf-quic-http-16 . . . . . . . . . . . . . . 68
B.18. Since draft-ietf-quic-http-15 . . . . . . . . . . . . . . 67 B.18. Since draft-ietf-quic-http-15 . . . . . . . . . . . . . . 68
B.19. Since draft-ietf-quic-http-14 . . . . . . . . . . . . . . 67 B.19. Since draft-ietf-quic-http-14 . . . . . . . . . . . . . . 68
B.20. Since draft-ietf-quic-http-13 . . . . . . . . . . . . . . 68 B.20. Since draft-ietf-quic-http-13 . . . . . . . . . . . . . . 69
B.21. Since draft-ietf-quic-http-12 . . . . . . . . . . . . . . 68 B.21. Since draft-ietf-quic-http-12 . . . . . . . . . . . . . . 69
B.22. Since draft-ietf-quic-http-11 . . . . . . . . . . . . . . 68 B.22. Since draft-ietf-quic-http-11 . . . . . . . . . . . . . . 69
B.23. Since draft-ietf-quic-http-10 . . . . . . . . . . . . . . 68 B.23. Since draft-ietf-quic-http-10 . . . . . . . . . . . . . . 69
B.24. Since draft-ietf-quic-http-09 . . . . . . . . . . . . . . 68 B.24. Since draft-ietf-quic-http-09 . . . . . . . . . . . . . . 70
B.25. Since draft-ietf-quic-http-08 . . . . . . . . . . . . . . 69 B.25. Since draft-ietf-quic-http-08 . . . . . . . . . . . . . . 70
B.26. Since draft-ietf-quic-http-07 . . . . . . . . . . . . . . 69 B.26. Since draft-ietf-quic-http-07 . . . . . . . . . . . . . . 70
B.27. Since draft-ietf-quic-http-06 . . . . . . . . . . . . . . 69 B.27. Since draft-ietf-quic-http-06 . . . . . . . . . . . . . . 70
B.28. Since draft-ietf-quic-http-05 . . . . . . . . . . . . . . 69 B.28. Since draft-ietf-quic-http-05 . . . . . . . . . . . . . . 70
B.29. Since draft-ietf-quic-http-04 . . . . . . . . . . . . . . 69 B.29. Since draft-ietf-quic-http-04 . . . . . . . . . . . . . . 70
B.30. Since draft-ietf-quic-http-03 . . . . . . . . . . . . . . 70 B.30. Since draft-ietf-quic-http-03 . . . . . . . . . . . . . . 71
B.31. Since draft-ietf-quic-http-02 . . . . . . . . . . . . . . 70 B.31. Since draft-ietf-quic-http-02 . . . . . . . . . . . . . . 71
B.32. Since draft-ietf-quic-http-01 . . . . . . . . . . . . . . 70 B.32. Since draft-ietf-quic-http-01 . . . . . . . . . . . . . . 71
B.33. Since draft-ietf-quic-http-00 . . . . . . . . . . . . . . 70 B.33. Since draft-ietf-quic-http-00 . . . . . . . . . . . . . . 71
B.34. Since draft-shade-quic-http2-mapping-00 . . . . . . . . . 71 B.34. Since draft-shade-quic-http2-mapping-00 . . . . . . . . . 72
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 71 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 72
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 72 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 73
1. Introduction 1. Introduction
HTTP semantics ([SEMANTICS]) are used for a broad range of services HTTP semantics ([SEMANTICS]) are used for a broad range of services
on the Internet. These semantics have most commonly been used with on the Internet. These semantics have most commonly been used with
HTTP/1.1, over a variety of transport and session layers, and with HTTP/1.1 and HTTP/2. HTTP/1.1 has been used over a variety of
HTTP/2 over TLS. HTTP/3 supports the same semantics over a new transport and session layers, while HTTP/2 has been used primarily
with TLS over TCP. HTTP/3 supports the same semantics over a new
transport protocol, QUIC. transport protocol, QUIC.
1.1. Prior versions of HTTP 1.1. Prior versions of HTTP
HTTP/1.1 ([HTTP11]) uses whitespace-delimited text fields to convey HTTP/1.1 ([HTTP11]) uses whitespace-delimited text fields to convey
HTTP messages. While these exchanges are human-readable, using HTTP messages. While these exchanges are human-readable, using
whitespace for message formatting leads to parsing complexity and whitespace for message formatting leads to parsing complexity and
excessive tolerance of variant behavior. Because HTTP/1.x does not excessive tolerance of variant behavior.
include a multiplexing layer, multiple TCP connections are often used
to service requests in parallel. However, that has a negative impact Because HTTP/1.1 does not include a multiplexing layer, multiple TCP
on congestion control and network efficiency, since TCP does not connections are often used to service requests in parallel. However,
share congestion control across multiple connections. that has a negative impact on congestion control and network
efficiency, since TCP does not share congestion control across
multiple connections.
HTTP/2 ([HTTP2]) introduced a binary framing and multiplexing layer HTTP/2 ([HTTP2]) introduced a binary framing and multiplexing layer
to improve latency without modifying the transport layer. However, to improve latency without modifying the transport layer. However,
because the parallel nature of HTTP/2's multiplexing is not visible because the parallel nature of HTTP/2's multiplexing is not visible
to TCP's loss recovery mechanisms, a lost or reordered packet causes to TCP's loss recovery mechanisms, a lost or reordered packet causes
all active transactions to experience a stall regardless of whether all active transactions to experience a stall regardless of whether
that transaction was directly impacted by the lost packet. that transaction was directly impacted by the lost packet.
1.2. Delegation to QUIC 1.2. Delegation to QUIC
The QUIC transport protocol incorporates stream multiplexing and per- The QUIC transport protocol incorporates stream multiplexing and per-
stream flow control, similar to that provided by the HTTP/2 framing stream flow control, similar to that provided by the HTTP/2 framing
layer. By providing reliability at the stream level and congestion layer. By providing reliability at the stream level and congestion
control across the entire connection, QUIC has the capability to control across the entire connection, QUIC has the capability to
improve the performance of HTTP compared to a TCP mapping. QUIC also improve the performance of HTTP compared to a TCP mapping. QUIC also
incorporates TLS 1.3 ([TLS13]) at the transport layer, offering incorporates TLS 1.3 ([TLS13]) at the transport layer, offering
comparable confidentiality and integrity to running TLS over TCP, comparable confidentiality and integrity to running TLS over TCP,
with the improved connection setup latency of TCP Fast Open ([TFO]). with the improved connection setup latency of TCP Fast Open ([TFO]).
This document defines a mapping of HTTP semantics over the QUIC This document defines HTTP/3, a mapping of HTTP semantics over the
transport protocol, drawing heavily on the design of HTTP/2. While QUIC transport protocol, drawing heavily on the design of HTTP/2.
delegating stream lifetime and flow control issues to QUIC, a similar HTTP/3 relies on QUIC to provide confidentiality and integrity
binary framing is used on each stream. Some HTTP/2 features are protection of data; peer authentication; and reliable, in-order, per-
subsumed by QUIC, while other features are implemented atop QUIC. stream delivery. While delegating stream lifetime and flow control
issues to QUIC, a binary framing similar to the HTTP/2 framing is
used on each stream. Some HTTP/2 features are subsumed by QUIC,
while other features are implemented atop QUIC.
QUIC is described in [QUIC-TRANSPORT]. For a full description of QUIC is described in [QUIC-TRANSPORT]. For a full description of
HTTP/2, see [HTTP2]. HTTP/2, see [HTTP2].
2. HTTP/3 Protocol Overview 2. HTTP/3 Protocol Overview
HTTP/3 provides a transport for HTTP semantics using the QUIC HTTP/3 provides a transport for HTTP semantics using the QUIC
transport protocol and an internal framing layer similar to HTTP/2. transport protocol and an internal framing layer similar to HTTP/2.
Once a client knows that an HTTP/3 server exists at a certain Once a client knows that an HTTP/3 server exists at a certain
endpoint, it opens a QUIC connection. QUIC provides protocol endpoint, it opens a QUIC connection. QUIC provides protocol
negotiation, stream-based multiplexing, and flow control. Discovery negotiation, stream-based multiplexing, and flow control. Discovery
of an HTTP/3 endpoint is described in Section 3.1. of an HTTP/3 endpoint is described in Section 3.1.
Within each stream, the basic unit of HTTP/3 communication is a frame Within each stream, the basic unit of HTTP/3 communication is a frame
(Section 7.2). Each frame type serves a different purpose. For (Section 7.2). Each frame type serves a different purpose. For
example, HEADERS and DATA frames form the basis of HTTP requests and example, HEADERS and DATA frames form the basis of HTTP requests and
responses (Section 4.1). responses (Section 4.1). Frames that apply to the entire connection
are conveyed on a dedicated control stream.
Multiplexing of requests is performed using the QUIC stream Multiplexing of requests is performed using the QUIC stream
abstraction, described in Section 2 of [QUIC-TRANSPORT]. Each abstraction, described in Section 2 of [QUIC-TRANSPORT]. Each
request-response pair consumes a single QUIC stream. Streams are request-response pair consumes a single QUIC stream. Streams are
independent of each other, so one stream that is blocked or suffers independent of each other, so one stream that is blocked or suffers
packet loss does not prevent progress on other streams. packet loss does not prevent progress on other streams.
Server push is an interaction mode introduced in HTTP/2 ([HTTP2]) Server push is an interaction mode introduced in HTTP/2 ([HTTP2])
that permits a server to push a request-response exchange to a client that permits a server to push a request-response exchange to a client
in anticipation of the client making the indicated request. This in anticipation of the client making the indicated request. This
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server: The endpoint that accepts an HTTP/3 connection. Servers server: The endpoint that accepts an HTTP/3 connection. Servers
receive HTTP requests and send HTTP responses. receive HTTP requests and send HTTP responses.
stream: A bidirectional or unidirectional bytestream provided by the stream: A bidirectional or unidirectional bytestream provided by the
QUIC transport. All streams within an HTTP/3 connection can be QUIC transport. All streams within an HTTP/3 connection can be
considered "HTTP/3 streams," but multiple stream types are defined considered "HTTP/3 streams," but multiple stream types are defined
within HTTP/3. within HTTP/3.
stream error: An application-level error on the individual stream. stream error: An application-level error on the individual stream.
The term "payload data" is defined in Section 6.4 of [SEMANTICS]. The term "content" is defined in Section 6.4 of [SEMANTICS].
Finally, the terms "resource", "message", "user agent", "origin Finally, the terms "resource", "message", "user agent", "origin
server", "gateway", "intermediary", "proxy", and "tunnel" are defined server", "gateway", "intermediary", "proxy", and "tunnel" are defined
in Section 3 of [SEMANTICS]. in Section 3 of [SEMANTICS].
Packet diagrams in this document use the format defined in Packet diagrams in this document use the format defined in
Section 1.3 of [QUIC-TRANSPORT] to illustrate the order and size of Section 1.3 of [QUIC-TRANSPORT] to illustrate the order and size of
fields. fields.
3. Connection Setup and Management 3. Connection Setup and Management
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Finally, the terms "resource", "message", "user agent", "origin Finally, the terms "resource", "message", "user agent", "origin
server", "gateway", "intermediary", "proxy", and "tunnel" are defined server", "gateway", "intermediary", "proxy", and "tunnel" are defined
in Section 3 of [SEMANTICS]. in Section 3 of [SEMANTICS].
Packet diagrams in this document use the format defined in Packet diagrams in this document use the format defined in
Section 1.3 of [QUIC-TRANSPORT] to illustrate the order and size of Section 1.3 of [QUIC-TRANSPORT] to illustrate the order and size of
fields. fields.
3. Connection Setup and Management 3. Connection Setup and Management
3.1. Discovering an HTTP/3 Endpoint 3.1. Discovering an HTTP/3 Endpoint
HTTP relies on the notion of an authoritative response: a response HTTP relies on the notion of an authoritative response: a response
that has been determined to be the most appropriate response for that that has been determined to be the most appropriate response for that
request given the state of the target resource at the time of request given the state of the target resource at the time of
response message origination by (or at the direction of) the origin response message origination by (or at the direction of) the origin
server identified within the target URI. Locating an authoritative server identified within the target URI. Locating an authoritative
server for an HTTP URL is discussed in Section 4.3 of [SEMANTICS]. server for an HTTP URI is discussed in Section 4.3 of [SEMANTICS].
The "https" scheme associates authority with possession of a The "https" scheme associates authority with possession of a
certificate that the client considers to be trustworthy for the host certificate that the client considers to be trustworthy for the host
identified by the authority component of the URL. identified by the authority component of the URI. Upon receiving a
server certificate in the TLS handshake, the client MUST verify that
If a server presents a valid certificate and proof that it controls the certificate is an acceptable match for the URI's origin server
the corresponding private key, then a client will accept a secured using the process described in Section 4.3.4 of [SEMANTICS]. If the
TLS session with that server as being authoritative for all origins certificate cannot be verified with respect to the URI's origin
with the "https" scheme and a host identified in the certificate. server, the client MUST NOT consider the server authoritative for
The host must be listed either as the CN field of the certificate that origin.
subject or as a dNSName in the subjectAltName field of the
certificate; see [RFC6125]. For a host that is an IP address, the
client MUST verify that the address appears as an iPAddress in the
subjectAltName field of the certificate.
If the hostname or address is not present in the certificate, the
client MUST NOT consider the server authoritative for origins
containing that hostname or address. See Section 4.3 of [SEMANTICS]
for more detail on authoritative access.
A client MAY attempt access to a resource with an "https" URI by A client MAY attempt access to a resource with an "https" URI by
resolving the host identifier to an IP address, establishing a QUIC resolving the host identifier to an IP address, establishing a QUIC
connection to that address on the indicated port, and sending an connection to that address on the indicated port (including
HTTP/3 request message targeting the URI to the server over that validation of the server certificate as described above), and sending
an HTTP/3 request message targeting the URI to the server over that
secured connection. Unless some other mechanism is used to select secured connection. Unless some other mechanism is used to select
HTTP/3, the token "h3" is used in the Application Layer Protocol HTTP/3, the token "h3" is used in the Application Layer Protocol
Negotiation (ALPN; see [RFC7301]) extension during the TLS handshake. Negotiation (ALPN; see [RFC7301]) extension during the TLS handshake.
Connectivity problems (e.g., blocking UDP) can result in QUIC Connectivity problems (e.g., blocking UDP) can result in QUIC
connection establishment failure; clients SHOULD attempt to use TCP- connection establishment failure; clients SHOULD attempt to use TCP-
based versions of HTTP in this case. based versions of HTTP in this case.
Servers MAY serve HTTP/3 on any UDP port; an alternative service Servers MAY serve HTTP/3 on any UDP port; an alternative service
advertisement always includes an explicit port, and URLs contain advertisement always includes an explicit port, and URIs contain
either an explicit port or a default port associated with the scheme. either an explicit port or a default port associated with the scheme.
3.1.1. HTTP Alternative Services 3.1.1. HTTP Alternative Services
An HTTP origin advertises the availability of an equivalent HTTP/3 An HTTP origin can advertise the availability of an equivalent HTTP/3
endpoint via the Alt-Svc HTTP response header field or the HTTP/2 endpoint via the Alt-Svc HTTP response header field or the HTTP/2
ALTSVC frame ([ALTSVC]), using the "h3" ALPN token. ALTSVC frame ([ALTSVC]), using the "h3" ALPN token.
For example, an origin could indicate in an HTTP response that HTTP/3 For example, an origin could indicate in an HTTP response that HTTP/3
was available on UDP port 50781 at the same hostname by including the was available on UDP port 50781 at the same hostname by including the
following header field: following header field:
Alt-Svc: h3=":50781" Alt-Svc: h3=":50781"
On receipt of an Alt-Svc record indicating HTTP/3 support, a client On receipt of an Alt-Svc record indicating HTTP/3 support, a client
MAY attempt to establish a QUIC connection to the indicated host and MAY attempt to establish a QUIC connection to the indicated host and
port; if this connection is successful, the client can send HTTP port; if this connection is successful, the client can send HTTP
requests using the mapping described in this document. requests using the mapping described in this document.
3.1.2. Other Schemes 3.1.2. Other Schemes
Although HTTP is independent of the transport protocol, the "http" Although HTTP is independent of the transport protocol, the "http"
scheme associates authority with the ability to receive TCP scheme associates authority with the ability to receive TCP
connections on the indicated port of whatever host is identified connections on the indicated port of whatever host is identified
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3.2. Connection Establishment 3.2. Connection Establishment
HTTP/3 relies on QUIC version 1 as the underlying transport. The use HTTP/3 relies on QUIC version 1 as the underlying transport. The use
of other QUIC transport versions with HTTP/3 MAY be defined by future of other QUIC transport versions with HTTP/3 MAY be defined by future
specifications. specifications.
QUIC version 1 uses TLS version 1.3 or greater as its handshake QUIC version 1 uses TLS version 1.3 or greater as its handshake
protocol. HTTP/3 clients MUST support a mechanism to indicate the protocol. HTTP/3 clients MUST support a mechanism to indicate the
target host to the server during the TLS handshake. If the server is target host to the server during the TLS handshake. If the server is
identified by a DNS name, clients MUST send the Server Name identified by a domain name ([DNS-TERMS]), clients MUST send the
Indication (SNI; [RFC6066]) TLS extension unless an alternative Server Name Indication (SNI; [RFC6066]) TLS extension unless an
mechanism to indicate the target host is used. alternative mechanism to indicate the target host is used.
QUIC connections are established as described in [QUIC-TRANSPORT]. QUIC connections are established as described in [QUIC-TRANSPORT].
During connection establishment, HTTP/3 support is indicated by During connection establishment, HTTP/3 support is indicated by
selecting the ALPN token "h3" in the TLS handshake. Support for selecting the ALPN token "h3" in the TLS handshake. Support for
other application-layer protocols MAY be offered in the same other application-layer protocols MAY be offered in the same
handshake. handshake.
While connection-level options pertaining to the core QUIC protocol While connection-level options pertaining to the core QUIC protocol
are set in the initial crypto handshake, HTTP/3-specific settings are are set in the initial crypto handshake, HTTP/3-specific settings are
conveyed in the SETTINGS frame. After the QUIC connection is conveyed in the SETTINGS frame. After the QUIC connection is
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3.3. Connection Reuse 3.3. Connection Reuse
HTTP/3 connections are persistent across multiple requests. For best HTTP/3 connections are persistent across multiple requests. For best
performance, it is expected that clients will not close connections performance, it is expected that clients will not close connections
until it is determined that no further communication with a server is until it is determined that no further communication with a server is
necessary (for example, when a user navigates away from a particular necessary (for example, when a user navigates away from a particular
web page) or until the server closes the connection. web page) or until the server closes the connection.
Once a connection exists to a server endpoint, this connection MAY be Once a connection exists to a server endpoint, this connection MAY be
reused for requests with multiple different URI authority components. reused for requests with multiple different URI authority components.
Clients SHOULD NOT open more than one HTTP/3 connection to a given To use an existing connection for a new origin, clients MUST validate
host and port pair, where the host is derived from a URI, a selected the certificate presented by the server for the new origin server
alternative service ([ALTSVC]), or a configured proxy. A client MAY using the process described in Section 4.3.4 of [SEMANTICS]. This
open multiple HTTP/3 connections to the same IP address and UDP port implies that clients will need to retain the server certificate and
using different transport or TLS configurations but SHOULD avoid any additional information needed to verify that certificate; clients
creating multiple connections with the same configuration. which do not do so will be unable to reuse the connection for
additional origins.
If the certificate is not acceptable with regard to the new origin
for any reason, the connection MUST NOT be reused and a new
connection SHOULD be established for the new origin. If the reason
the certificate cannot be verified might apply to other origins
already associated with the connection, the client SHOULD re-validate
the server certificate for those origins. For instance, if
validation of a certificate fails because the certificate has expired
or been revoked, this might be used to invalidate all other origins
for which that certificate was used to establish authority.
Clients SHOULD NOT open more than one HTTP/3 connection to a given IP
address and UDP port, where the IP address and port might be derived
from a URI, a selected alternative service ([ALTSVC]), a configured
proxy, or name resolution of any of these. A client MAY open
multiple HTTP/3 connections to the same IP address and UDP port using
different transport or TLS configurations but SHOULD avoid creating
multiple connections with the same configuration.
Servers are encouraged to maintain open HTTP/3 connections for as Servers are encouraged to maintain open HTTP/3 connections for as
long as possible but are permitted to terminate idle connections if long as possible but are permitted to terminate idle connections if
necessary. When either endpoint chooses to close the HTTP/3 necessary. When either endpoint chooses to close the HTTP/3
connection, the terminating endpoint SHOULD first send a GOAWAY frame connection, the terminating endpoint SHOULD first send a GOAWAY frame
(Section 5.2) so that both endpoints can reliably determine whether (Section 5.2) so that both endpoints can reliably determine whether
previously sent frames have been processed and gracefully complete or previously sent frames have been processed and gracefully complete or
terminate any necessary remaining tasks. terminate any necessary remaining tasks.
A server that does not wish clients to reuse HTTP/3 connections for a A server that does not wish clients to reuse HTTP/3 connections for a
particular origin can indicate that it is not authoritative for a particular origin can indicate that it is not authoritative for a
request by sending a 421 (Misdirected Request) status code in request by sending a 421 (Misdirected Request) status code in
response to the request; see Section 9.1.2 of [HTTP2]. response to the request; see Section 7.4 of [SEMANTICS].
4. HTTP Request Lifecycle 4. HTTP Request Lifecycle
4.1. HTTP Message Exchanges 4.1. HTTP Message Exchanges
A client sends an HTTP request on a request stream, which is a A client sends an HTTP request on a request stream, which is a
client-initiated bidirectional QUIC stream; see Section 6.1. A client-initiated bidirectional QUIC stream; see Section 6.1. A
client MUST send only a single request on a given stream. A server client MUST send only a single request on a given stream. A server
sends zero or more interim HTTP responses on the same stream as the sends zero or more interim HTTP responses on the same stream as the
request, followed by a single final HTTP response, as detailed below. request, followed by a single final HTTP response, as detailed below.
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responses, followed by a single final HTTP response, in the same responses, followed by a single final HTTP response, in the same
manner as a standard response. Push is described in more detail in manner as a standard response. Push is described in more detail in
Section 4.4. Section 4.4.
On a given stream, receipt of multiple requests or receipt of an On a given stream, receipt of multiple requests or receipt of an
additional HTTP response following a final HTTP response MUST be additional HTTP response following a final HTTP response MUST be
treated as malformed (Section 4.1.3). treated as malformed (Section 4.1.3).
An HTTP message (request or response) consists of: An HTTP message (request or response) consists of:
1. the header field section, sent as a single HEADERS frame (see 1. the header section, sent as a single HEADERS frame (see
Section 7.2.2), Section 7.2.2),
2. optionally, the payload data, if present, sent as a series of 2. optionally, the content, if present, sent as a series of DATA
DATA frames (see Section 7.2.1), and frames (see Section 7.2.1), and
3. optionally, the trailer field section, if present, sent as a 3. optionally, the trailer section, if present, sent as a single
single HEADERS frame. HEADERS frame.
Header and trailer field sections are described in Sections 6.3 and Header and trailer sections are described in Sections 6.3 and 6.5 of
6.5 of [SEMANTICS]; the payload data is described in Section 6.4 of [SEMANTICS]; the content is described in Section 6.4 of [SEMANTICS].
[SEMANTICS].
Receipt of an invalid sequence of frames MUST be treated as a Receipt of an invalid sequence of frames MUST be treated as a
connection error of type H3_FRAME_UNEXPECTED; see Section 8. In connection error of type H3_FRAME_UNEXPECTED; see Section 8. In
particular, a DATA frame before any HEADERS frame, or a HEADERS or particular, a DATA frame before any HEADERS frame, or a HEADERS or
DATA frame after the trailing HEADERS frame is considered invalid. DATA frame after the trailing HEADERS frame, is considered invalid.
Other frame types, especially unknown frame types, might be permitted Other frame types, especially unknown frame types, might be permitted
subject to their own rules; see Section 9. subject to their own rules; see Section 9.
A server MAY send one or more PUSH_PROMISE frames (Section 7.2.5) A server MAY send one or more PUSH_PROMISE frames (Section 7.2.5)
before, after, or interleaved with the frames of a response message. before, after, or interleaved with the frames of a response message.
These PUSH_PROMISE frames are not part of the response; see These PUSH_PROMISE frames are not part of the response; see
Section 4.4 for more details. PUSH_PROMISE frames are not permitted Section 4.4 for more details. PUSH_PROMISE frames are not permitted
on push streams; a pushed response that includes PUSH_PROMISE frames on push streams; a pushed response that includes PUSH_PROMISE frames
MUST be treated as a connection error of type H3_FRAME_UNEXPECTED; MUST be treated as a connection error of type H3_FRAME_UNEXPECTED;
see Section 8. see Section 8.
Frames of unknown types (Section 9), including reserved frames Frames of unknown types (Section 9), including reserved frames
(Section 7.2.8) MAY be sent on a request or push stream before, (Section 7.2.8) MAY be sent on a request or push stream before,
after, or interleaved with other frames described in this section. after, or interleaved with other frames described in this section.
The HEADERS and PUSH_PROMISE frames might reference updates to the The HEADERS and PUSH_PROMISE frames might reference updates to the
QPACK dynamic table. While these updates are not directly part of QPACK dynamic table. While these updates are not directly part of
the message exchange, they must be received and processed before the the message exchange, they must be received and processed before the
message can be consumed. See Section 4.1.1 for more details. message can be consumed. See Section 4.1.1 for more details.
The "chunked" transfer encoding defined in Section 7.1 of [HTTP11] Transfer codings (see Section 6.1 of [HTTP11]) are not defined for
MUST NOT be used. HTTP/3; the Transfer-Encoding header field MUST NOT be used.
A response MAY consist of multiple messages when and only when one or A response MAY consist of multiple messages when and only when one or
more interim responses (1xx; see Section 15.2 of [SEMANTICS]) precede more interim responses (1xx; see Section 15.2 of [SEMANTICS]) precede
a final response to the same request. Interim responses do not a final response to the same request. Interim responses do not
contain payload data or trailers. contain content or trailer sections.
An HTTP request/response exchange fully consumes a client-initiated An HTTP request/response exchange fully consumes a client-initiated
bidirectional QUIC stream. After sending a request, a client MUST bidirectional QUIC stream. After sending a request, a client MUST
close the stream for sending. Unless using the CONNECT method (see close the stream for sending. Unless using the CONNECT method (see
Section 4.2), clients MUST NOT make stream closure dependent on Section 4.2), clients MUST NOT make stream closure dependent on
receiving a response to their request. After sending a final receiving a response to their request. After sending a final
response, the server MUST close the stream for sending. At this response, the server MUST close the stream for sending. At this
point, the QUIC stream is fully closed. point, the QUIC stream is fully closed.
When a stream is closed, this indicates the end of the final HTTP When a stream is closed, this indicates the end of the final HTTP
message. Because some messages are large or unbounded, endpoints message. Because some messages are large or unbounded, endpoints
SHOULD begin processing partial HTTP messages once enough of the SHOULD begin processing partial HTTP messages once enough of the
message has been received to make progress. If a client-initiated message has been received to make progress. If a client-initiated
stream terminates without enough of the HTTP message to provide a stream terminates without enough of the HTTP message to provide a
complete response, the server SHOULD abort its response with the complete response, the server SHOULD abort its response stream with
error code H3_REQUEST_INCOMPLETE; see Section 8. the error code H3_REQUEST_INCOMPLETE; see Section 8.
A server can send a complete response prior to the client sending an A server can send a complete response prior to the client sending an
entire request if the response does not depend on any portion of the entire request if the response does not depend on any portion of the
request that has not been sent and received. When the server does request that has not been sent and received. When the server does
not need to receive the remainder of the request, it MAY abort not need to receive the remainder of the request, it MAY abort
reading the request stream, send a complete response, and cleanly reading the request stream, send a complete response, and cleanly
close the sending part of the stream. The error code H3_NO_ERROR close the sending part of the stream. The error code H3_NO_ERROR
SHOULD be used when requesting that the client stop sending on the SHOULD be used when requesting that the client stop sending on the
request stream. Clients MUST NOT discard complete responses as a request stream. Clients MUST NOT discard complete responses as a
result of having their request terminated abruptly, though clients result of having their request terminated abruptly, though clients
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HTTP messages carry metadata as a series of key-value pairs called HTTP messages carry metadata as a series of key-value pairs called
HTTP fields; see Sections 6.3 and 6.5 of [SEMANTICS]. For a listing HTTP fields; see Sections 6.3 and 6.5 of [SEMANTICS]. For a listing
of registered HTTP fields, see the "Hypertext Transfer Protocol of registered HTTP fields, see the "Hypertext Transfer Protocol
(HTTP) Field Name Registry" maintained at (HTTP) Field Name Registry" maintained at
<https://www.iana.org/assignments/http-fields/>. <https://www.iana.org/assignments/http-fields/>.
*Note:* This registry will not exist until [SEMANTICS] is *Note:* This registry will not exist until [SEMANTICS] is
approved. *RFC Editor*, please remove this note prior to approved. *RFC Editor*, please remove this note prior to
publication. publication.
As in previous versions of HTTP, field names are strings containing a Field names are strings containing a subset of ASCII characters.
subset of ASCII characters that are compared in a case-insensitive Properties of HTTP field names and values are discussed in more
fashion. Properties of HTTP field names and values are discussed in detail in Section 5.1 of [SEMANTICS]. As in HTTP/2, characters in
more detail in Section 5.1 of [SEMANTICS]. As in HTTP/2, characters field names MUST be converted to lowercase prior to their encoding.
in field names MUST be converted to lowercase prior to their A request or response containing uppercase characters in field names
encoding. A request or response containing uppercase characters in MUST be treated as malformed (Section 4.1.3).
field names MUST be treated as malformed (Section 4.1.3).
Like HTTP/2, HTTP/3 does not use the Connection header field to Like HTTP/2, HTTP/3 does not use the Connection header field to
indicate connection-specific fields; in this protocol, connection- indicate connection-specific fields; in this protocol, connection-
specific metadata is conveyed by other means. An endpoint MUST NOT specific metadata is conveyed by other means. An endpoint MUST NOT
generate an HTTP/3 field section containing connection-specific generate an HTTP/3 field section containing connection-specific
fields; any message containing connection-specific fields MUST be fields; any message containing connection-specific fields MUST be
treated as malformed (Section 4.1.3). treated as malformed (Section 4.1.3).
The only exception to this is the TE header field, which MAY be The only exception to this is the TE header field, which MAY be
present in an HTTP/3 request header; when it is, it MUST NOT contain present in an HTTP/3 request header; when it is, it MUST NOT contain
any value other than "trailers". any value other than "trailers".
This means that an intermediary transforming an HTTP/1.x message to An intermediary transforming an HTTP/1.x message to HTTP/3 MUST
HTTP/3 will need to remove any fields nominated by the Connection remove connection-specific header fields as discussed in
field, along with the Connection field itself. Such intermediaries Section 7.6.1 of [SEMANTICS], or their messages will be treated by
SHOULD also remove other connection-specific fields, such as Keep- other HTTP/3 endpoints as malformed (Section 4.1.3).
Alive, Proxy-Connection, Transfer-Encoding, and Upgrade, even if they
are not nominated by the Connection field.
4.1.1.1. Pseudo-Header Fields 4.1.1.1. Pseudo-Header Fields
Like HTTP/2, HTTP/3 employs a series of pseudo-header fields where Like HTTP/2, HTTP/3 employs a series of pseudo-header fields where
the field name begins with the ':' character (ASCII 0x3a). These the field name begins with the ':' character (ASCII 0x3a). These
pseudo-header fields convey the target URI, the method of the pseudo-header fields convey the target URI, the method of the
request, and the status code for the response. request, and the status code for the response.
Pseudo-header fields are not HTTP fields. Endpoints MUST NOT Pseudo-header fields are not HTTP fields. Endpoints MUST NOT
generate pseudo-header fields other than those defined in this generate pseudo-header fields other than those defined in this
document; however, an extension could negotiate a modification of document; however, an extension could negotiate a modification of
this restriction; see Section 9. this restriction; see Section 9.
Pseudo-header fields are only valid in the context in which they are Pseudo-header fields are only valid in the context in which they are
defined. Pseudo-header fields defined for requests MUST NOT appear defined. Pseudo-header fields defined for requests MUST NOT appear
in responses; pseudo-header fields defined for responses MUST NOT in responses; pseudo-header fields defined for responses MUST NOT
appear in requests. Pseudo-header fields MUST NOT appear in appear in requests. Pseudo-header fields MUST NOT appear in trailer
trailers. Endpoints MUST treat a request or response that contains sections. Endpoints MUST treat a request or response that contains
undefined or invalid pseudo-header fields as malformed undefined or invalid pseudo-header fields as malformed
(Section 4.1.3). (Section 4.1.3).
All pseudo-header fields MUST appear in the header field section All pseudo-header fields MUST appear in the header section before
before regular header fields. Any request or response that contains regular header fields. Any request or response that contains a
a pseudo-header field that appears in a header field section after a pseudo-header field that appears in a header section after a regular
regular header field MUST be treated as malformed (Section 4.1.3). header field MUST be treated as malformed (Section 4.1.3).
The following pseudo-header fields are defined for requests: The following pseudo-header fields are defined for requests:
":method": Contains the HTTP method (Section 9 of [SEMANTICS]) ":method": Contains the HTTP method (Section 9 of [SEMANTICS])
":scheme": Contains the scheme portion of the target URI ":scheme": Contains the scheme portion of the target URI
(Section 3.1 of [URI]) (Section 3.1 of [URI])
":scheme" is not restricted to "http" and "https" schemed URIs. A ":scheme" is not restricted to URIs with scheme "http" and
proxy or gateway can translate requests for non-HTTP schemes, "https". A proxy or gateway can translate requests for non-HTTP
enabling the use of HTTP to interact with non-HTTP services. schemes, enabling the use of HTTP to interact with non-HTTP
services.
See Section 3.1.2 for guidance on using a scheme other than
"https".
":authority": Contains the authority portion of the target URI ":authority": Contains the authority portion of the target URI
(Section 3.2 of [URI]). The authority MUST NOT include the (Section 3.2 of [URI]). The authority MUST NOT include the
deprecated "userinfo" subcomponent for "http" or "https" schemed deprecated "userinfo" subcomponent for URIs of scheme "http" or
URIs. "https".
To ensure that the HTTP/1.1 request line can be reproduced To ensure that the HTTP/1.1 request line can be reproduced
accurately, this pseudo-header field MUST be omitted when accurately, this pseudo-header field MUST be omitted when
translating from an HTTP/1.1 request that has a request target in translating from an HTTP/1.1 request that has a request target in
origin or asterisk form; see Section 3.2 of [HTTP11]. Clients origin or asterisk form; see Section 7.1 of [SEMANTICS]. Clients
that generate HTTP/3 requests directly SHOULD use the ":authority" that generate HTTP/3 requests directly SHOULD use the ":authority"
pseudo-header field instead of the Host field. An intermediary pseudo-header field instead of the Host field. An intermediary
that converts an HTTP/3 request to HTTP/1.1 MUST create a Host that converts an HTTP/3 request to HTTP/1.1 MUST create a Host
field if one is not present in a request by copying the value of field if one is not present in a request by copying the value of
the ":authority" pseudo-header field. the ":authority" pseudo-header field.
":path": Contains the path and query parts of the target URI (the ":path": Contains the path and query parts of the target URI (the
"path-absolute" production and optionally a '?' character followed "path-absolute" production and optionally a '?' character followed
by the "query" production; see Sections 3.3 and 3.4 of [URI]. A by the "query" production; see Sections 3.3 and 3.4 of [URI]. A
request in asterisk form includes the value '*' for the ":path" request in asterisk form includes the value '*' for the ":path"
pseudo-header field. pseudo-header field.
This pseudo-header field MUST NOT be empty for "http" or "https" This pseudo-header field MUST NOT be empty for "http" or "https"
URIs; "http" or "https" URIs that do not contain a path component URIs; "http" or "https" URIs that do not contain a path component
MUST include a value of '/'. The exception to this rule is an MUST include a value of '/'. The exception to this rule is an
OPTIONS request for an "http" or "https" URI that does not include OPTIONS request for an "http" or "https" URI that does not include
a path component; these MUST include a ":path" pseudo-header field a path component; these MUST include a ":path" pseudo-header field
with a value of '*'; see Section 3.2.4 of [HTTP11]. with a value of '*'; see Section 7.1 of [SEMANTICS].
All HTTP/3 requests MUST include exactly one value for the ":method", All HTTP/3 requests MUST include exactly one value for the ":method",
":scheme", and ":path" pseudo-header fields, unless it is a CONNECT ":scheme", and ":path" pseudo-header fields, unless it is a CONNECT
request; see Section 4.2. request; see Section 4.2.
If the ":scheme" pseudo-header field identifies a scheme that has a If the ":scheme" pseudo-header field identifies a scheme that has a
mandatory authority component (including "http" and "https"), the mandatory authority component (including "http" and "https"), the
request MUST contain either an ":authority" pseudo-header field or a request MUST contain either an ":authority" pseudo-header field or a
"Host" header field. If these fields are present, they MUST NOT be "Host" header field. If these fields are present, they MUST NOT be
empty. If both fields are present, they MUST contain the same value. empty. If both fields are present, they MUST contain the same value.
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For responses, a single ":status" pseudo-header field is defined that For responses, a single ":status" pseudo-header field is defined that
carries the HTTP status code; see Section 15 of [SEMANTICS]. This carries the HTTP status code; see Section 15 of [SEMANTICS]. This
pseudo-header field MUST be included in all responses; otherwise, the pseudo-header field MUST be included in all responses; otherwise, the
response is malformed (Section 4.1.3). response is malformed (Section 4.1.3).
HTTP/3 does not define a way to carry the version or reason phrase HTTP/3 does not define a way to carry the version or reason phrase
that is included in an HTTP/1.1 status line. that is included in an HTTP/1.1 status line.
4.1.1.2. Field Compression 4.1.1.2. Field Compression
HTTP/3 uses QPACK field compression as described in [QPACK], a [QPACK] describes a variation of HPACK that gives an encoder some
variation of HPACK that allows the flexibility to avoid compression- control over how much head-of-line blocking can be caused by
induced head-of-line blocking. See that document for additional compression. This allows an encoder to balance compression
details. efficiency with latency. HTTP/3 uses QPACK to compress header and
trailer sections, including the pseudo-header fields present in the
header section.
To allow for better compression efficiency, the "Cookie" field To allow for better compression efficiency, the "Cookie" field
([RFC6265]) MAY be split into separate field lines, each with one or ([RFC6265]) MAY be split into separate field lines, each with one or
more cookie-pairs, before compression. If a decompressed field more cookie-pairs, before compression. If a decompressed field
section contains multiple cookie field lines, these MUST be section contains multiple cookie field lines, these MUST be
concatenated into a single octet string using the two-octet delimiter concatenated into a single byte string using the two-byte delimiter
of 0x3b, 0x20 (the ASCII string "; ") before being passed into a of 0x3b, 0x20 (the ASCII string "; ") before being passed into a
context other than HTTP/2 or HTTP/3, such as an HTTP/1.1 connection, context other than HTTP/2 or HTTP/3, such as an HTTP/1.1 connection,
or a generic HTTP server application. or a generic HTTP server application.
4.1.1.3. Header Size Constraints 4.1.1.3. Header Size Constraints
An HTTP/3 implementation MAY impose a limit on the maximum size of An HTTP/3 implementation MAY impose a limit on the maximum size of
the message header it will accept on an individual HTTP message. A the message header it will accept on an individual HTTP message. A
server that receives a larger header section than it is willing to server that receives a larger header section than it is willing to
handle can send an HTTP 431 (Request Header Fields Too Large) status handle can send an HTTP 431 (Request Header Fields Too Large) status
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process. The size of a field list is calculated based on the process. The size of a field list is calculated based on the
uncompressed size of fields, including the length of the name and uncompressed size of fields, including the length of the name and
value in bytes plus an overhead of 32 bytes for each field. value in bytes plus an overhead of 32 bytes for each field.
If an implementation wishes to advise its peer of this limit, it can If an implementation wishes to advise its peer of this limit, it can
be conveyed as a number of bytes in the be conveyed as a number of bytes in the
SETTINGS_MAX_FIELD_SECTION_SIZE parameter. An implementation that SETTINGS_MAX_FIELD_SECTION_SIZE parameter. An implementation that
has received this parameter SHOULD NOT send an HTTP message header has received this parameter SHOULD NOT send an HTTP message header
that exceeds the indicated size, as the peer will likely refuse to that exceeds the indicated size, as the peer will likely refuse to
process it. However, an HTTP message can traverse one or more process it. However, an HTTP message can traverse one or more
intermediaries before reaching the origin server; see Section 3.6 of intermediaries before reaching the origin server; see Section 3.7 of
[SEMANTICS]. Because this limit is applied separately by each [SEMANTICS]. Because this limit is applied separately by each
implementation which processes the message, messages below this limit implementation which processes the message, messages below this limit
are not guaranteed to be accepted. are not guaranteed to be accepted.
4.1.2. Request Cancellation and Rejection 4.1.2. Request Cancellation and Rejection
Once a request stream has been opened, the request MAY be cancelled Once a request stream has been opened, the request MAY be cancelled
by either endpoint. Clients cancel requests if the response is no by either endpoint. Clients cancel requests if the response is no
longer of interest; servers cancel requests if they are unable to or longer of interest; servers cancel requests if they are unable to or
choose not to respond. When possible, it is RECOMMENDED that servers choose not to respond. When possible, it is RECOMMENDED that servers
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o invalid values for pseudo-header fields, o invalid values for pseudo-header fields,
o pseudo-header fields after fields, o pseudo-header fields after fields,
o an invalid sequence of HTTP messages, o an invalid sequence of HTTP messages,
o the inclusion of uppercase field names, or o the inclusion of uppercase field names, or
o the inclusion of invalid characters in field names or values. o the inclusion of invalid characters in field names or values.
A request or response that includes payload data can include a A request or response that is defined as having content when it
Content-Length header field. A request or response is also malformed contains a Content-Length header field (Section 6.4.1 of
if the value of a Content-Length header field does not equal the sum [SEMANTICS]), is malformed if the value of a Content-Length header
of the DATA frame lengths that form the payload data. A response field does not equal the sum of the DATA frame lengths received. A
that is defined to have no payload, as described in Section 6.4 of response that is defined as never having content, even when a
[SEMANTICS], can have a non-zero Content-Length field, even though no Content-Length is present, can have a non-zero Content-Length field
content is included in DATA frames. even though no content is included in DATA frames.
Intermediaries that process HTTP requests or responses (i.e., any Intermediaries that process HTTP requests or responses (i.e., any
intermediary not acting as a tunnel) MUST NOT forward a malformed intermediary not acting as a tunnel) MUST NOT forward a malformed
request or response. Malformed requests or responses that are request or response. Malformed requests or responses that are
detected MUST be treated as a stream error (Section 8) of type detected MUST be treated as a stream error (Section 8) of type
H3_MESSAGE_ERROR. H3_MESSAGE_ERROR.
For malformed requests, a server MAY send an HTTP response indicating For malformed requests, a server MAY send an HTTP response indicating
the error prior to closing or resetting the stream. Clients MUST NOT the error prior to closing or resetting the stream. Clients MUST NOT
accept a malformed response. Note that these requirements are accept a malformed response. Note that these requirements are
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method is used to establish a tunnel over a single stream. method is used to establish a tunnel over a single stream.
A CONNECT request MUST be constructed as follows: A CONNECT request MUST be constructed as follows:
o The ":method" pseudo-header field is set to "CONNECT" o The ":method" pseudo-header field is set to "CONNECT"
o The ":scheme" and ":path" pseudo-header fields are omitted o The ":scheme" and ":path" pseudo-header fields are omitted
o The ":authority" pseudo-header field contains the host and port to o The ":authority" pseudo-header field contains the host and port to
connect to (equivalent to the authority-form of the request-target connect to (equivalent to the authority-form of the request-target
of CONNECT requests; see Section 3.2.3 of [HTTP11]) of CONNECT requests; see Section 7.1 of [SEMANTICS])
The request stream remains open at the end of the request to carry The request stream remains open at the end of the request to carry
the data to be transferred. A CONNECT request that does not conform the data to be transferred. A CONNECT request that does not conform
to these restrictions is malformed; see Section 4.1.3. to these restrictions is malformed; see Section 4.1.3.
A proxy that supports CONNECT establishes a TCP connection A proxy that supports CONNECT establishes a TCP connection
([RFC0793]) to the server identified in the ":authority" pseudo- ([RFC0793]) to the server identified in the ":authority" pseudo-
header field. Once this connection is successfully established, the header field. Once this connection is successfully established, the
proxy sends a HEADERS frame containing a 2xx series status code to proxy sends a HEADERS frame containing a 2xx series status code to
the client, as defined in Section 15.3 of [SEMANTICS]. the client, as defined in Section 15.3 of [SEMANTICS].
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expect to receive data from the target of the CONNECT. expect to receive data from the target of the CONNECT.
A TCP connection error is signaled by abruptly terminating the A TCP connection error is signaled by abruptly terminating the
stream. A proxy treats any error in the TCP connection, which stream. A proxy treats any error in the TCP connection, which
includes receiving a TCP segment with the RST bit set, as a stream includes receiving a TCP segment with the RST bit set, as a stream
error of type H3_CONNECT_ERROR; see Section 8. Correspondingly, if a error of type H3_CONNECT_ERROR; see Section 8. Correspondingly, if a
proxy detects an error with the stream or the QUIC connection, it proxy detects an error with the stream or the QUIC connection, it
MUST close the TCP connection. If the underlying TCP implementation MUST close the TCP connection. If the underlying TCP implementation
permits it, the proxy SHOULD send a TCP segment with the RST bit set. permits it, the proxy SHOULD send a TCP segment with the RST bit set.
Since CONNECT creates a tunnel to an arbitrary server, proxies that
support CONNECT SHOULD restrict its use to a set of known ports or a
list of safe request targets; see Section 9.3.6 of [SEMANTICS] for
more detail.
4.3. HTTP Upgrade 4.3. HTTP Upgrade
HTTP/3 does not support the HTTP Upgrade mechanism (Section 7.8 of HTTP/3 does not support the HTTP Upgrade mechanism (Section 7.8 of
[SEMANTICS]) or 101 (Switching Protocols) informational status code [SEMANTICS]) or 101 (Switching Protocols) informational status code
(Section 15.2.2 of [SEMANTICS]). (Section 15.2.2 of [SEMANTICS]).
4.4. Server Push 4.4. Server Push
Server push is an interaction mode that permits a server to push a Server push is an interaction mode that permits a server to push a
request-response exchange to a client in anticipation of the client request-response exchange to a client in anticipation of the client
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Section 7.2.3. Clients use this frame to indicate they do not wish Section 7.2.3. Clients use this frame to indicate they do not wish
to receive a promised resource. Servers use this frame to indicate to receive a promised resource. Servers use this frame to indicate
they will not be fulfilling a previous promise. they will not be fulfilling a previous promise.
Not all requests can be pushed. A server MAY push requests that have Not all requests can be pushed. A server MAY push requests that have
the following properties: the following properties:
o cacheable; see Section 9.2.3 of [SEMANTICS] o cacheable; see Section 9.2.3 of [SEMANTICS]
o safe; see Section 9.2.1 of [SEMANTICS] o safe; see Section 9.2.1 of [SEMANTICS]
o does not include a request body or trailer section o does not include a request body or trailer section
The server MUST include a value in the ":authority" pseudo-header The server MUST include a value in the ":authority" pseudo-header
field for which the server is authoritative; see Section 3.3. field for which the server is authoritative. If the client has not
yet validated the connection for the origin indicated by the pushed
request, it MUST perform the same verification process it would do
before sending a request for that origin on the connection; see
Section 3.3. If this verification fails, the client MUST NOT
consider the server authoritative for that origin.
Clients SHOULD send a CANCEL_PUSH frame upon receipt of a Clients SHOULD send a CANCEL_PUSH frame upon receipt of a
PUSH_PROMISE frame carrying a request that is not cacheable, is not PUSH_PROMISE frame carrying a request that is not cacheable, is not
known to be safe, that indicates the presence of a request body, or known to be safe, that indicates the presence of a request body, or
for which it does not consider the server authoritative. Any for which it does not consider the server authoritative. Any
corresponding responses MUST NOT be used or cached. corresponding responses MUST NOT be used or cached.
Each pushed response is associated with one or more client requests. Each pushed response is associated with one or more client requests.
The push is associated with the request stream on which the The push is associated with the request stream on which the
PUSH_PROMISE frame was received. The same server push can be PUSH_PROMISE frame was received. The same server push can be
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requests with a Stream ID greater than or equal to the identifier requests with a Stream ID greater than or equal to the identifier
contained in the GOAWAY frame, those requests will not be contained in the GOAWAY frame, those requests will not be
processed. Clients can safely retry unprocessed requests on a processed. Clients can safely retry unprocessed requests on a
different HTTP connection. A client that is unable to retry different HTTP connection. A client that is unable to retry
requests loses all requests that are in flight when the server requests loses all requests that are in flight when the server
closes the connection. closes the connection.
Requests on Stream IDs less than the Stream ID in a GOAWAY frame Requests on Stream IDs less than the Stream ID in a GOAWAY frame
from the server might have been processed; their status cannot be from the server might have been processed; their status cannot be
known until a response is received, the stream is reset known until a response is received, the stream is reset
individually, another GOAWAY is received, or the connection individually, another GOAWAY is received with a lower Stream ID
than that of the request in question, or the connection
terminates. terminates.
Servers MAY reject individual requests on streams below the Servers MAY reject individual requests on streams below the
indicated ID if these requests were not processed. indicated ID if these requests were not processed.
o If a server receives a GOAWAY frame after having promised pushes o If a server receives a GOAWAY frame after having promised pushes
with a Push ID greater than or equal to the identifier contained with a Push ID greater than or equal to the identifier contained
in the GOAWAY frame, those pushes will not be accepted. in the GOAWAY frame, those pushes will not be accepted.
Servers SHOULD send a GOAWAY frame when the closing of a connection Servers SHOULD send a GOAWAY frame when the closing of a connection
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the peer indicating that the application layer has terminated the the peer indicating that the application layer has terminated the
connection. The application error code in this frame indicates to connection. The application error code in this frame indicates to
the peer why the connection is being closed. See Section 8 for error the peer why the connection is being closed. See Section 8 for error
codes that can be used when closing a connection in HTTP/3. codes that can be used when closing a connection in HTTP/3.
Before closing the connection, a GOAWAY frame MAY be sent to allow Before closing the connection, a GOAWAY frame MAY be sent to allow
the client to retry some requests. Including the GOAWAY frame in the the client to retry some requests. Including the GOAWAY frame in the
same packet as the QUIC CONNECTION_CLOSE frame improves the chances same packet as the QUIC CONNECTION_CLOSE frame improves the chances
of the frame being received by clients. of the frame being received by clients.
If there are open streams that have not been explicitly closed, they
are implicitly closed when the connection is closed; see Section 10.2
of [QUIC-TRANSPORT].
5.4. Transport Closure 5.4. Transport Closure
For various reasons, the QUIC transport could indicate to the For various reasons, the QUIC transport could indicate to the
application layer that the connection has terminated. This might be application layer that the connection has terminated. This might be
due to an explicit closure by the peer, a transport-level error, or a due to an explicit closure by the peer, a transport-level error, or a
change in network topology that interrupts connectivity. change in network topology that interrupts connectivity.
If a connection terminates without a GOAWAY frame, clients MUST If a connection terminates without a GOAWAY frame, clients MUST
assume that any request that was sent, whether in whole or in part, assume that any request that was sent, whether in whole or in part,
might have been processed. might have been processed.
6. Stream Mapping and Usage 6. Stream Mapping and Usage
A QUIC stream provides reliable in-order delivery of bytes, but makes A QUIC stream provides reliable in-order delivery of bytes, but makes
no guarantees about order of delivery with regard to bytes on other no guarantees about order of delivery with regard to bytes on other
streams. On the wire, data is framed into QUIC STREAM frames, but streams. On the wire, the stream data containing HTTP frames is
this framing is invisible to the HTTP framing layer. The transport carried by QUIC STREAM frames, but this framing is invisible to the
layer buffers and orders received QUIC STREAM frames, exposing the HTTP framing layer. The transport layer buffers and orders received
data contained within as a reliable byte stream to the application. QUIC STREAM frames, exposing the data contained within as a reliable
Although QUIC permits out-of-order delivery within a stream, HTTP/3 byte stream to the application. Although QUIC permits out-of-order
does not make use of this feature. delivery within a stream, HTTP/3 does not make use of this feature.
QUIC streams can be either unidirectional, carrying data only from QUIC streams can be either unidirectional, carrying data only from
initiator to receiver, or bidirectional. Streams can be initiated by initiator to receiver, or bidirectional. Streams can be initiated by
either the client or the server. For more detail on QUIC streams, either the client or the server. For more detail on QUIC streams,
see Section 2 of [QUIC-TRANSPORT]. see Section 2 of [QUIC-TRANSPORT].
When HTTP fields and data are sent over QUIC, the QUIC layer handles When HTTP fields and data are sent over QUIC, the QUIC layer handles
most of the stream management. HTTP does not need to do any separate most of the stream management. HTTP does not need to do any separate
multiplexing when using QUIC - data sent over a QUIC stream always multiplexing when using QUIC - data sent over a QUIC stream always
maps to a particular HTTP transaction or to the entire HTTP/3 maps to a particular HTTP transaction or to the entire HTTP/3
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All client-initiated bidirectional streams are used for HTTP requests All client-initiated bidirectional streams are used for HTTP requests
and responses. A bidirectional stream ensures that the response can and responses. A bidirectional stream ensures that the response can
be readily correlated with the request. These streams are referred be readily correlated with the request. These streams are referred
to as request streams. to as request streams.
This means that the client's first request occurs on QUIC stream 0, This means that the client's first request occurs on QUIC stream 0,
with subsequent requests on stream 4, 8, and so on. In order to with subsequent requests on stream 4, 8, and so on. In order to
permit these streams to open, an HTTP/3 server SHOULD configure non- permit these streams to open, an HTTP/3 server SHOULD configure non-
zero minimum values for the number of permitted streams and the zero minimum values for the number of permitted streams and the
initial stream flow control window. So as to not unnecessarily limit initial stream flow control window. So as to not unnecessarily limit
parallelism, at least 100 requests SHOULD be permitted at a time. parallelism, at least 100 request streams SHOULD be permitted at a
time.
HTTP/3 does not use server-initiated bidirectional streams, though an HTTP/3 does not use server-initiated bidirectional streams, though an
extension could define a use for these streams. Clients MUST treat extension could define a use for these streams. Clients MUST treat
receipt of a server-initiated bidirectional stream as a connection receipt of a server-initiated bidirectional stream as a connection
error of type H3_STREAM_CREATION_ERROR (Section 8) unless such an error of type H3_STREAM_CREATION_ERROR (Section 8) unless such an
extension has been negotiated. extension has been negotiated.
6.2. Unidirectional Streams 6.2. Unidirectional Streams
Unidirectional streams, in either direction, are used for a range of Unidirectional streams, in either direction, are used for a range of
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type, this MUST be treated as a connection error of type type, this MUST be treated as a connection error of type
H3_MISSING_SETTINGS. Only one control stream per peer is permitted; H3_MISSING_SETTINGS. Only one control stream per peer is permitted;
receipt of a second stream claiming to be a control stream MUST be receipt of a second stream claiming to be a control stream MUST be
treated as a connection error of type H3_STREAM_CREATION_ERROR. The treated as a connection error of type H3_STREAM_CREATION_ERROR. The
sender MUST NOT close the control stream, and the receiver MUST NOT sender MUST NOT close the control stream, and the receiver MUST NOT
request that the sender close the control stream. If either control request that the sender close the control stream. If either control
stream is closed at any point, this MUST be treated as a connection stream is closed at any point, this MUST be treated as a connection
error of type H3_CLOSED_CRITICAL_STREAM. Connection errors are error of type H3_CLOSED_CRITICAL_STREAM. Connection errors are
described in Section 8. described in Section 8.
Because the contents of the control stream are used to manage the
behavior of other streams, endpoints SHOULD provide enough flow
control credit to keep the peer's control stream from becoming
blocked.
A pair of unidirectional streams is used rather than a single A pair of unidirectional streams is used rather than a single
bidirectional stream. This allows either peer to send data as soon bidirectional stream. This allows either peer to send data as soon
as it is able. Depending on whether 0-RTT is enabled on the QUIC as it is able. Depending on whether 0-RTT is available on the QUIC
connection, either client or server might be able to send stream data connection, either client or server might be able to send stream data
first after the cryptographic handshake completes. first.
6.2.2. Push Streams 6.2.2. Push Streams
Server push is an optional feature introduced in HTTP/2 that allows a Server push is an optional feature introduced in HTTP/2 that allows a
server to initiate a response before a request has been made. See server to initiate a response before a request has been made. See
Section 4.4 for more details. Section 4.4 for more details.
A push stream is indicated by a stream type of 0x01, followed by the A push stream is indicated by a stream type of 0x01, followed by the
Push ID of the promise that it fulfills, encoded as a variable-length Push ID of the promise that it fulfills, encoded as a variable-length
integer. The remaining data on this stream consists of HTTP/3 integer. The remaining data on this stream consists of HTTP/3
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| | | | | | | | | | | |
| MAX_PUSH_ID | Yes | No | No | Section 7.2 | | MAX_PUSH_ID | Yes | No | No | Section 7.2 |
| | | | | .7 | | | | | | .7 |
| | | | | | | | | | | |
| Reserved | Yes | Yes | Yes | Section 7.2 | | Reserved | Yes | Yes | Yes | Section 7.2 |
| | | | | .8 | | | | | | .8 |
+--------------+------------+-------------+-----------+-------------+ +--------------+------------+-------------+-----------+-------------+
Table 1: HTTP/3 Frames and Stream Type Overview Table 1: HTTP/3 Frames and Stream Type Overview
Certain frames can only occur as the first frame of a particular The SETTINGS frame can only occur as the first frame of a Control
stream type; these are indicated in Table 1 with a (1). Specific stream; this is indicated in Table 1 with a (1). Specific guidance
guidance is provided in the relevant section. is provided in the relevant section.
Note that, unlike QUIC frames, HTTP/3 frames can span multiple Note that, unlike QUIC frames, HTTP/3 frames can span multiple
packets. packets.
7.1. Frame Layout 7.1. Frame Layout
All frames have the following format: All frames have the following format:
HTTP/3 Frame Format { HTTP/3 Frame Format {
Type (i), Type (i),
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Length: A variable-length integer that describes the length in bytes Length: A variable-length integer that describes the length in bytes
of the Frame Payload. of the Frame Payload.
Frame Payload: A payload, the semantics of which are determined by Frame Payload: A payload, the semantics of which are determined by
the Type field. the Type field.
Each frame's payload MUST contain exactly the fields identified in Each frame's payload MUST contain exactly the fields identified in
its description. A frame payload that contains additional bytes its description. A frame payload that contains additional bytes
after the identified fields or a frame payload that terminates before after the identified fields or a frame payload that terminates before
the end of the identified fields MUST be treated as a connection the end of the identified fields MUST be treated as a connection
error of type H3_FRAME_ERROR; see Section 8. error of type H3_FRAME_ERROR; see Section 8. In particular,
redundant length encodings MUST be verified to be self-consistent;
see Section 10.8.
When a stream terminates cleanly, if the last frame on the stream was When a stream terminates cleanly, if the last frame on the stream was
truncated, this MUST be treated as a connection error of type truncated, this MUST be treated as a connection error of type
H3_FRAME_ERROR; see Section 8. Streams that terminate abruptly may H3_FRAME_ERROR; see Section 8. Streams that terminate abruptly may
be reset at any point in a frame. be reset at any point in a frame.
7.2. Frame Definitions 7.2. Frame Definitions
7.2.1. DATA 7.2.1. DATA
DATA frames (type=0x0) convey arbitrary, variable-length sequences of DATA frames (type=0x0) convey arbitrary, variable-length sequences of
bytes associated with HTTP request or response payload data. bytes associated with HTTP request or response content.
DATA frames MUST be associated with an HTTP request or response. If DATA frames MUST be associated with an HTTP request or response. If
a DATA frame is received on a control stream, the recipient MUST a DATA frame is received on a control stream, the recipient MUST
respond with a connection error of type H3_FRAME_UNEXPECTED; see respond with a connection error of type H3_FRAME_UNEXPECTED; see
Section 8. Section 8.
DATA Frame { DATA Frame {
Type (i) = 0x0, Type (i) = 0x0,
Length (i), Length (i),
Data (..), Data (..),
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client SHOULD abort reading the stream with an error code of client SHOULD abort reading the stream with an error code of
H3_REQUEST_CANCELLED. H3_REQUEST_CANCELLED.
A CANCEL_PUSH frame is sent on the control stream. Receiving a A CANCEL_PUSH frame is sent on the control stream. Receiving a
CANCEL_PUSH frame on a stream other than the control stream MUST be CANCEL_PUSH frame on a stream other than the control stream MUST be
treated as a connection error of type H3_FRAME_UNEXPECTED. treated as a connection error of type H3_FRAME_UNEXPECTED.
CANCEL_PUSH Frame { CANCEL_PUSH Frame {
Type (i) = 0x3, Type (i) = 0x3,
Length (i), Length (i),
Push ID (..), Push ID (i),
} }
Figure 6: CANCEL_PUSH Frame Figure 6: CANCEL_PUSH Frame
The CANCEL_PUSH frame carries a Push ID encoded as a variable-length The CANCEL_PUSH frame carries a Push ID encoded as a variable-length
integer. The Push ID identifies the server push that is being integer. The Push ID identifies the server push that is being
cancelled; see Section 4.4. If a CANCEL_PUSH frame is received that cancelled; see Section 4.4. If a CANCEL_PUSH frame is received that
references a Push ID greater than currently allowed on the references a Push ID greater than currently allowed on the
connection, this MUST be treated as a connection error of type connection, this MUST be treated as a connection error of type
H3_ID_ERROR. H3_ID_ERROR.
skipping to change at page 34, line 5 skipping to change at page 35, line 18
} }
SETTINGS Frame { SETTINGS Frame {
Type (i) = 0x4, Type (i) = 0x4,
Length (i), Length (i),
Setting (..) ..., Setting (..) ...,
} }
Figure 7: SETTINGS Frame Figure 7: SETTINGS Frame
An implementation MUST ignore the contents for any SETTINGS An implementation MUST ignore any parameter with an identifier it
identifier it does not understand. does not understand.
7.2.4.1. Defined SETTINGS Parameters 7.2.4.1. Defined SETTINGS Parameters
The following settings are defined in HTTP/3: The following settings are defined in HTTP/3:
SETTINGS_MAX_FIELD_SECTION_SIZE (0x6): The default value is SETTINGS_MAX_FIELD_SECTION_SIZE (0x6): The default value is
unlimited. See Section 4.1.1.3 for usage. unlimited. See Section 4.1.1.3 for usage.
Setting identifiers of the format "0x1f * N + 0x21" for non-negative Setting identifiers of the format "0x1f * N + 0x21" for non-negative
integer values of N are reserved to exercise the requirement that integer values of N are reserved to exercise the requirement that
unknown identifiers be ignored. Such settings have no defined unknown identifiers be ignored. Such settings have no defined
meaning. Endpoints SHOULD include at least one such setting in their meaning. Endpoints SHOULD include at least one such setting in their
SETTINGS frame. Endpoints MUST NOT consider such settings to have SETTINGS frame. Endpoints MUST NOT consider such settings to have
any meaning upon receipt. any meaning upon receipt.
Because the setting has no defined meaning, the value of the setting Because the setting has no defined meaning, the value of the setting
can be any value the implementation selects. can be any value the implementation selects.
Setting identifiers which were used in HTTP/2 where there is no Setting identifiers which were defined in [HTTP2] where there is no
corresponding HTTP/3 setting have also been reserved corresponding HTTP/3 setting have also been reserved
(Section 11.2.2). These settings MUST NOT be sent, and their receipt (Section 11.2.2). These reserved settings MUST NOT be sent, and
MUST be treated as a connection error of type H3_SETTINGS_ERROR. their receipt MUST be treated as a connection error of type
H3_SETTINGS_ERROR.
Additional settings can be defined by extensions to HTTP/3; see Additional settings can be defined by extensions to HTTP/3; see
Section 9 for more details. Section 9 for more details.
7.2.4.2. Initialization 7.2.4.2. Initialization
An HTTP implementation MUST NOT send frames or requests that would be An HTTP implementation MUST NOT send frames or requests that would be
invalid based on its current understanding of the peer's settings. invalid based on its current understanding of the peer's settings.
All settings begin at an initial value. Each endpoint SHOULD use All settings begin at an initial value. Each endpoint SHOULD use
skipping to change at page 35, line 48 skipping to change at page 37, line 13
with the previously specified settings, this MUST be treated as a with the previously specified settings, this MUST be treated as a
connection error of type H3_SETTINGS_ERROR. If a server accepts connection error of type H3_SETTINGS_ERROR. If a server accepts
0-RTT but then sends a SETTINGS frame that omits a setting value that 0-RTT but then sends a SETTINGS frame that omits a setting value that
the client understands (apart from reserved setting identifiers) that the client understands (apart from reserved setting identifiers) that
was previously specified to have a non-default value, this MUST be was previously specified to have a non-default value, this MUST be
treated as a connection error of type H3_SETTINGS_ERROR. treated as a connection error of type H3_SETTINGS_ERROR.
7.2.5. PUSH_PROMISE 7.2.5. PUSH_PROMISE
The PUSH_PROMISE frame (type=0x5) is used to carry a promised request The PUSH_PROMISE frame (type=0x5) is used to carry a promised request
header field section from server to client on a request stream, as in header section from server to client on a request stream, as in
HTTP/2. HTTP/2.
PUSH_PROMISE Frame { PUSH_PROMISE Frame {
Type (i) = 0x5, Type (i) = 0x5,
Length (i), Length (i),
Push ID (i), Push ID (i),
Encoded Field Section (..), Encoded Field Section (..),
} }
Figure 8: PUSH_PROMISE Frame Figure 8: PUSH_PROMISE Frame
skipping to change at page 41, line 31 skipping to change at page 42, line 40
Extensions are permitted to use new frame types (Section 7.2), new Extensions are permitted to use new frame types (Section 7.2), new
settings (Section 7.2.4.1), new error codes (Section 8), or new settings (Section 7.2.4.1), new error codes (Section 8), or new
unidirectional stream types (Section 6.2). Registries are unidirectional stream types (Section 6.2). Registries are
established for managing these extension points: frame types established for managing these extension points: frame types
(Section 11.2.1), settings (Section 11.2.2), error codes (Section 11.2.1), settings (Section 11.2.2), error codes
(Section 11.2.3), and stream types (Section 11.2.4). (Section 11.2.3), and stream types (Section 11.2.4).
Implementations MUST ignore unknown or unsupported values in all Implementations MUST ignore unknown or unsupported values in all
extensible protocol elements. Implementations MUST discard frames extensible protocol elements. Implementations MUST discard frames
and unidirectional streams that have unknown or unsupported types. and abort reading on unidirectional streams that have unknown or
This means that any of these extension points can be safely used by unsupported types. This means that any of these extension points can
extensions without prior arrangement or negotiation. However, where be safely used by extensions without prior arrangement or
a known frame type is required to be in a specific location, such as negotiation. However, where a known frame type is required to be in
the SETTINGS frame as the first frame of the control stream (see a specific location, such as the SETTINGS frame as the first frame of
Section 6.2.1), an unknown frame type does not satisfy that the control stream (see Section 6.2.1), an unknown frame type does
requirement and SHOULD be treated as an error. not satisfy that requirement and SHOULD be treated as an error.
Extensions that could change the semantics of existing protocol Extensions that could change the semantics of existing protocol
components MUST be negotiated before being used. For example, an components MUST be negotiated before being used. For example, an
extension that changes the layout of the HEADERS frame cannot be used extension that changes the layout of the HEADERS frame cannot be used
until the peer has given a positive signal that this is acceptable. until the peer has given a positive signal that this is acceptable.
Coordinating when such a revised layout comes into effect could prove Coordinating when such a revised layout comes into effect could prove
complex. As such, allocating new identifiers for new definitions of complex. As such, allocating new identifiers for new definitions of
existing protocol elements is likely to be more effective. existing protocol elements is likely to be more effective.
This document does not mandate a specific method for negotiating the This document does not mandate a specific method for negotiating the
skipping to change at page 44, line 9 skipping to change at page 45, line 15
to traffic analysis. to traffic analysis.
Compression of field sections also offers some opportunities to waste Compression of field sections also offers some opportunities to waste
processing resources; see Section 7 of [QPACK] for more details on processing resources; see Section 7 of [QPACK] for more details on
potential abuses. potential abuses.
All these features - i.e., server push, unknown protocol elements, All these features - i.e., server push, unknown protocol elements,
field compression - have legitimate uses. These features become a field compression - have legitimate uses. These features become a
burden only when they are used unnecessarily or to excess. burden only when they are used unnecessarily or to excess.
An endpoint that does not monitor this behavior exposes itself to a An endpoint that does not monitor such behavior exposes itself to a
risk of denial-of-service attack. Implementations SHOULD track the risk of denial-of-service attack. Implementations SHOULD track the
use of these features and set limits on their use. An endpoint MAY use of these features and set limits on their use. An endpoint MAY
treat activity that is suspicious as a connection error of type treat activity that is suspicious as a connection error of type
H3_EXCESSIVE_LOAD (Section 8), but false positives will result in H3_EXCESSIVE_LOAD (Section 8), but false positives will result in
disrupting valid connections and requests. disrupting valid connections and requests.
10.5.1. Limits on Field Section Size 10.5.1. Limits on Field Section Size
A large field section (Section 4.1) can cause an implementation to A large field section (Section 4.1) can cause an implementation to
commit a large amount of state. Header fields that are critical for commit a large amount of state. Header fields that are critical for
routing can appear toward the end of a header field section, which routing can appear toward the end of a header section, which prevents
prevents streaming of the header field section to its ultimate streaming of the header section to its ultimate destination. This
destination. This ordering and other reasons, such as ensuring cache ordering and other reasons, such as ensuring cache correctness, mean
correctness, mean that an endpoint likely needs to buffer the entire that an endpoint likely needs to buffer the entire header section.
header field section. Since there is no hard limit to the size of a Since there is no hard limit to the size of a field section, some
field section, some endpoints could be forced to commit a large endpoints could be forced to commit a large amount of available
amount of available memory for header fields. memory for header fields.
An endpoint can use the SETTINGS_MAX_FIELD_SECTION_SIZE An endpoint can use the SETTINGS_MAX_FIELD_SECTION_SIZE
(Section 4.1.1.3) setting to advise peers of limits that might apply (Section 4.1.1.3) setting to advise peers of limits that might apply
on the size of field sections. This setting is only advisory, so on the size of field sections. This setting is only advisory, so
endpoints MAY choose to send field sections that exceed this limit endpoints MAY choose to send field sections that exceed this limit
and risk having the request or response being treated as malformed. and risk having the request or response being treated as malformed.
This setting is specific to an HTTP/3 connection, so any request or This setting is specific to an HTTP/3 connection, so any request or
response could encounter a hop with a lower, unknown limit. An response could encounter a hop with a lower, unknown limit. An
intermediary can attempt to avoid this problem by passing on values intermediary can attempt to avoid this problem by passing on values
presented by different peers, but they are not obligated to do so. presented by different peers, but they are not obligated to do so.
A server that receives a larger field section than it is willing to A server that receives a larger field section than it is willing to
handle can send an HTTP 431 (Request Header Fields Too Large) status handle can send an HTTP 431 (Request Header Fields Too Large) status
code ([RFC6585]). A client can discard responses that it cannot code ([RFC6585]). A client can discard responses that it cannot
process. process.
10.5.2. CONNECT Issues 10.5.2. CONNECT Issues
The CONNECT method can be used to create disproportionate load on a The CONNECT method can be used to create disproportionate load on a
proxy, since stream creation is relatively inexpensive when compared proxy, since stream creation is relatively inexpensive when compared
to the creation and maintenance of a TCP connection. A proxy might to the creation and maintenance of a TCP connection. Therefore, a
also maintain some resources for a TCP connection beyond the closing proxy that supports CONNECT might be more conservative in the number
of the stream that carries the CONNECT request, since the outgoing of simultaneous requests it accepts.
TCP connection remains in the TIME_WAIT state. Therefore, a proxy
cannot rely on QUIC stream limits alone to control the resources A proxy might also maintain some resources for a TCP connection
consumed by CONNECT requests. beyond the closing of the stream that carries the CONNECT request,
since the outgoing TCP connection remains in the TIME_WAIT state. To
account for this, a proxy might delay increasing the QUIC stream
limits for some time after a TCP connection terminates.
10.6. Use of Compression 10.6. Use of Compression
Compression can allow an attacker to recover secret data when it is Compression can allow an attacker to recover secret data when it is
compressed in the same context as data under attacker control. compressed in the same context as data under attacker control.
HTTP/3 enables compression of fields (Section 4.1.1); the following HTTP/3 enables compression of fields (Section 4.1.1); the following
concerns also apply to the use of HTTP compressed content-codings; concerns also apply to the use of HTTP compressed content-codings;
see Section 8.5.1 of [SEMANTICS]. see Section 8.4.1 of [SEMANTICS].
There are demonstrable attacks on compression that exploit the There are demonstrable attacks on compression that exploit the
characteristics of the web (e.g., [BREACH]). The attacker induces characteristics of the web (e.g., [BREACH]). The attacker induces
multiple requests containing varying plaintext, observing the length multiple requests containing varying plaintext, observing the length
of the resulting ciphertext in each, which reveals a shorter length of the resulting ciphertext in each, which reveals a shorter length
when a guess about the secret is correct. when a guess about the secret is correct.
Implementations communicating on a secure channel MUST NOT compress Implementations communicating on a secure channel MUST NOT compress
content that includes both confidential and attacker-controlled data content that includes both confidential and attacker-controlled data
unless separate compression contexts are used for each source of unless separate compression contexts are used for each source of
data. Compression MUST NOT be used if the source of data cannot be data. Compression MUST NOT be used if the source of data cannot be
reliably determined. reliably determined.
Further considerations regarding the compression of fields sections Further considerations regarding the compression of field sections
are described in [QPACK]. are described in [QPACK].
10.7. Padding and Traffic Analysis 10.7. Padding and Traffic Analysis
Padding can be used to obscure the exact size of frame content and is Padding can be used to obscure the exact size of frame content and is
provided to mitigate specific attacks within HTTP, for example, provided to mitigate specific attacks within HTTP, for example,
attacks where compressed content includes both attacker-controlled attacks where compressed content includes both attacker-controlled
plaintext and secret data (e.g., [BREACH]). plaintext and secret data (e.g., [BREACH]).
Where HTTP/2 employs PADDING frames and Padding fields in other Where HTTP/2 employs PADDING frames and Padding fields in other
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Several protocol elements contain nested length elements, typically Several protocol elements contain nested length elements, typically
in the form of frames with an explicit length containing variable- in the form of frames with an explicit length containing variable-
length integers. This could pose a security risk to an incautious length integers. This could pose a security risk to an incautious
implementer. An implementation MUST ensure that the length of a implementer. An implementation MUST ensure that the length of a
frame exactly matches the length of the fields it contains. frame exactly matches the length of the fields it contains.
10.9. Early Data 10.9. Early Data
The use of 0-RTT with HTTP/3 creates an exposure to replay attack. The use of 0-RTT with HTTP/3 creates an exposure to replay attack.
The anti-replay mitigations in [HTTP-REPLAY] MUST be applied when The anti-replay mitigations in [HTTP-REPLAY] MUST be applied when
using HTTP/3 with 0-RTT. using HTTP/3 with 0-RTT. When applying [HTTP-REPLAY] to HTTP/3,
references to the TLS layer refer to the handshake performed within
QUIC, while all references to application data refer to the contents
of streams.
10.10. Migration 10.10. Migration
Certain HTTP implementations use the client address for logging or Certain HTTP implementations use the client address for logging or
access-control purposes. Since a QUIC client's address might change access-control purposes. Since a QUIC client's address might change
during a connection (and future versions might support simultaneous during a connection (and future versions might support simultaneous
use of multiple addresses), such implementations will need to either use of multiple addresses), such implementations will need to either
actively retrieve the client's current address or addresses when they actively retrieve the client's current address or addresses when they
are relevant or explicitly accept that the original address might are relevant or explicitly accept that the original address might
change. change.
skipping to change at page 48, line 13 skipping to change at page 49, line 33
Permanent registrations in this registry are assigned using the Permanent registrations in this registry are assigned using the
Specification Required policy ([RFC8126]), except for values between Specification Required policy ([RFC8126]), except for values between
0x00 and 0x3f (in hexadecimal; inclusive), which are assigned using 0x00 and 0x3f (in hexadecimal; inclusive), which are assigned using
Standards Action or IESG Approval as defined in Section 4.9 and 4.10 Standards Action or IESG Approval as defined in Section 4.9 and 4.10
of [RFC8126]. of [RFC8126].
While this registry is separate from the "HTTP/2 Frame Type" registry While this registry is separate from the "HTTP/2 Frame Type" registry
defined in [HTTP2], it is preferable that the assignments parallel defined in [HTTP2], it is preferable that the assignments parallel
each other where the code spaces overlap. If an entry is present in each other where the code spaces overlap. If an entry is present in
only one registry, every effort SHOULD be made to avoid assigning the only one registry, every effort SHOULD be made to avoid assigning the
corresponding value to an unrelated operation. corresponding value to an unrelated operation. Expert reviewers MAY
reject unrelated registrations which would conflict with the same
value in the corresponding registry.
In addition to common fields as described in Section 11.2, permanent In addition to common fields as described in Section 11.2, permanent
registrations in this registry MUST include the following field: registrations in this registry MUST include the following field:
Frame Type: A name or label for the frame type. Frame Type: A name or label for the frame type.
Specifications of frame types MUST include a description of the frame Specifications of frame types MUST include a description of the frame
layout and its semantics, including any parts of the frame that are layout and its semantics, including any parts of the frame that are
conditionally present. conditionally present.
skipping to change at page 50, line 5 skipping to change at page 51, line 4
registrations in this registry are assigned using the Specification registrations in this registry are assigned using the Specification
Required policy ([RFC8126]), except for values between 0x00 and 0x3f Required policy ([RFC8126]), except for values between 0x00 and 0x3f
(in hexadecimal; inclusive), which are assigned using Standards (in hexadecimal; inclusive), which are assigned using Standards
Action or IESG Approval as defined in Section 4.9 and 4.10 of Action or IESG Approval as defined in Section 4.9 and 4.10 of
[RFC8126]. [RFC8126].
While this registry is separate from the "HTTP/2 Settings" registry While this registry is separate from the "HTTP/2 Settings" registry
defined in [HTTP2], it is preferable that the assignments parallel defined in [HTTP2], it is preferable that the assignments parallel
each other. If an entry is present in only one registry, every each other. If an entry is present in only one registry, every
effort SHOULD be made to avoid assigning the corresponding value to effort SHOULD be made to avoid assigning the corresponding value to
an unrelated operation. an unrelated operation. Expert reviewers MAY reject unrelated
registrations which would conflict with the same value in the
corresponding registry.
In addition to common fields as described in Section 11.2, permanent In addition to common fields as described in Section 11.2, permanent
registrations in this registry MUST include the following fields: registrations in this registry MUST include the following fields:
Setting Name: A symbolic name for the setting. Specifying a setting Setting Name: A symbolic name for the setting. Specifying a setting
name is optional. name is optional.
Default: The value of the setting unless otherwise indicated. A Default: The value of the setting unless otherwise indicated. A
default SHOULD be the most restrictive possible value. default SHOULD be the most restrictive possible value.
The entries in Table 3 are registered by this document. The entries in Table 3 are registered by this document.
+------------------------+-------+------------------+-----------+ +------------------------+-------+------------------+-----------+
| Setting Name | Value | Specification | Default | | Setting Name | Value | Specification | Default |
+------------------------+-------+------------------+-----------+ +------------------------+-------+------------------+-----------+
| Reserved | 0x0 | N/A | N/A |
| | | | |
| Reserved | 0x2 | N/A | N/A | | Reserved | 0x2 | N/A | N/A |
| | | | | | | | | |
| Reserved | 0x3 | N/A | N/A | | Reserved | 0x3 | N/A | N/A |
| | | | | | | | | |
| Reserved | 0x4 | N/A | N/A | | Reserved | 0x4 | N/A | N/A |
| | | | | | | | | |
| Reserved | 0x5 | N/A | N/A | | Reserved | 0x5 | N/A | N/A |
| | | | | | | | | |
| MAX_FIELD_SECTION_SIZE | 0x6 | Section 7.2.4.1 | Unlimited | | MAX_FIELD_SECTION_SIZE | 0x6 | Section 7.2.4.1 | Unlimited |
+------------------------+-------+------------------+-----------+ +------------------------+-------+------------------+-----------+
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Required policy ([RFC8126]), except for values between 0x00 and 0x3f Required policy ([RFC8126]), except for values between 0x00 and 0x3f
(in hexadecimal; inclusive), which are assigned using Standards (in hexadecimal; inclusive), which are assigned using Standards
Action or IESG Approval as defined in Section 4.9 and 4.10 of Action or IESG Approval as defined in Section 4.9 and 4.10 of
[RFC8126]. [RFC8126].
Registrations for error codes are required to include a description Registrations for error codes are required to include a description
of the error code. An expert reviewer is advised to examine new of the error code. An expert reviewer is advised to examine new
registrations for possible duplication with existing error codes. registrations for possible duplication with existing error codes.
Use of existing registrations is to be encouraged, but not mandated. Use of existing registrations is to be encouraged, but not mandated.
Use of values that are registered in the "HTTP/2 Error Code" registry Use of values that are registered in the "HTTP/2 Error Code" registry
is discouraged. is discouraged, and expert reviewers MAY reject such registrations.
In addition to common fields as described in Section 11.2, this In addition to common fields as described in Section 11.2, this
registry includes two additional fields. Permanent registrations in registry includes two additional fields. Permanent registrations in
this registry MUST include the following field: this registry MUST include the following field:
Name: A name for the error code. Name: A name for the error code.
Description: A brief description of the error code semantics. Description: A brief description of the error code semantics.
The entries in Table 4 are registered by this document. These error The entries in Table 4 are registered by this document. These error
codes were selected from the range that operates on a Specification codes were selected from the range that operates on a Specification
Required policy to avoid collisions with HTTP/2 error codes. Required policy to avoid collisions with HTTP/2 error codes.
+---------------------------+--------+--------------+---------------+ +---------------------------+-------+---------------+---------------+
| Name | Value | Description | Specification | | Name | Value | Description | Specification |
+---------------------------+--------+--------------+---------------+ +---------------------------+-------+---------------+---------------+
| H3_NO_ERROR | 0x0100 | No error | Section 8.1 | | H3_NO_ERROR | 0x100 | No error | Section 8.1 |
| | | | | | | | | |
| H3_GENERAL_PROTOCOL_ERROR | 0x0101 | General | Section 8.1 | | H3_GENERAL_PROTOCOL_ERROR | 0x101 | General | Section 8.1 |
| | | protocol | | | | | protocol | |
| | | error | | | | | error | |
| | | | | | | | | |
| H3_INTERNAL_ERROR | 0x0102 | Internal | Section 8.1 | | H3_INTERNAL_ERROR | 0x102 | Internal | Section 8.1 |
| | | error | | | | | error | |
| | | | | | | | | |
| H3_STREAM_CREATION_ERROR | 0x0103 | Stream | Section 8.1 | | H3_STREAM_CREATION_ERROR | 0x103 | Stream | Section 8.1 |
| | | creation | | | | | creation | |
| | | error | | | | | error | |
| | | | | | | | | |
| H3_CLOSED_CRITICAL_STREAM | 0x0104 | Critical | Section 8.1 | | H3_CLOSED_CRITICAL_STREAM | 0x104 | Critical | Section 8.1 |
| | | stream was | | | | | stream was | |
| | | closed | | | | | closed | |
| | | | | | | | | |
| H3_FRAME_UNEXPECTED | 0x0105 | Frame not | Section 8.1 | | H3_FRAME_UNEXPECTED | 0x105 | Frame not | Section 8.1 |
| | | permitted in | | | | | permitted in | |
| | | the current | | | | | the current | |
| | | state | | | | | state | |
| | | | | | | | | |
| H3_FRAME_ERROR | 0x0106 | Frame | Section 8.1 | | H3_FRAME_ERROR | 0x106 | Frame | Section 8.1 |
| | | violated | | | | | violated | |
| | | layout or | | | | | layout or | |
| | | size rules | | | | | size rules | |
| | | | | | | | | |
| H3_EXCESSIVE_LOAD | 0x0107 | Peer | Section 8.1 | | H3_EXCESSIVE_LOAD | 0x107 | Peer | Section 8.1 |
| | | generating | | | | | generating | |
| | | excessive | | | | | excessive | |
| | | load | | | | | load | |
| | | | | | | | | |
| H3_ID_ERROR | 0x0108 | An | Section 8.1 | | H3_ID_ERROR | 0x108 | An identifier | Section 8.1 |
| | | identifier | | | | | was used | |
| | | was used | | | | | incorrectly | |
| | | incorrectly | | | | | | |
| | | | | | H3_SETTINGS_ERROR | 0x109 | SETTINGS | Section 8.1 |
| H3_SETTINGS_ERROR | 0x0109 | SETTINGS | Section 8.1 | | | | frame | |
| | | frame | | | | | contained | |
| | | contained | | | | | invalid | |
| | | invalid | | | | | values | |
| | | values | | | | | | |
| | | | | | H3_MISSING_SETTINGS | 0x10a | No SETTINGS | Section 8.1 |
| H3_MISSING_SETTINGS | 0x010a | No SETTINGS | Section 8.1 | | | | frame | |
| | | frame | | | | | received | |
| | | received | | | | | | |
| | | | | | H3_REQUEST_REJECTED | 0x10b | Request not | Section 8.1 |
| H3_REQUEST_REJECTED | 0x010b | Request not | Section 8.1 | | | | processed | |
| | | processed | | | | | | |
| | | | | | H3_REQUEST_CANCELLED | 0x10c | Data no | Section 8.1 |
| H3_REQUEST_CANCELLED | 0x010c | Data no | Section 8.1 | | | | longer needed | |
| | | longer | | | | | | |
| | | needed | | | H3_REQUEST_INCOMPLETE | 0x10d | Stream | Section 8.1 |
| | | | | | | | terminated | |
| H3_REQUEST_INCOMPLETE | 0x010d | Stream | Section 8.1 | | | | early | |
| | | terminated | | | | | | |
| | | early | | | H3_MESSAGE_ERROR | 0x10e | Malformed | Section 8.1 |
| | | | | | | | message | |
| H3_MESSAGE_ERROR | 0x010e | Malformed | Section 8.1 | | | | | |
| | | message | | | H3_CONNECT_ERROR | 0x10f | TCP reset or | Section 8.1 |
| | | | | | | | error on | |
| H3_CONNECT_ERROR | 0x010f | TCP reset or | Section 8.1 | | | | CONNECT | |
| | | error on | | | | | request | |
| | | CONNECT | | | | | | |
| | | request | | | H3_VERSION_FALLBACK | 0x110 | Retry over | Section 8.1 |
| | | | | | | | HTTP/1.1 | |
| H3_VERSION_FALLBACK | 0x0110 | Retry over | Section 8.1 | +---------------------------+-------+---------------+---------------+
| | | HTTP/1.1 | |
+---------------------------+--------+--------------+---------------+
Table 4: Initial HTTP/3 Error Codes Table 4: Initial HTTP/3 Error Codes
Each code of the format "0x1f * N + 0x21" for non-negative integer Each code of the format "0x1f * N + 0x21" for non-negative integer
values of N (that is, 0x21, 0x40, ..., through 0x3ffffffffffffffe) values of N (that is, 0x21, 0x40, ..., through 0x3ffffffffffffffe)
MUST NOT be assigned by IANA and MUST NOT appear in the listing of MUST NOT be assigned by IANA and MUST NOT appear in the listing of
assigned values. assigned values.
11.2.4. Stream Types 11.2.4. Stream Types
skipping to change at page 54, line 6 skipping to change at page 55, line 6
12. References 12. References
12.1. Normative References 12.1. Normative References
[ALTSVC] Nottingham, M., McManus, P., and J. Reschke, "HTTP [ALTSVC] Nottingham, M., McManus, P., and J. Reschke, "HTTP
Alternative Services", RFC 7838, DOI 10.17487/RFC7838, Alternative Services", RFC 7838, DOI 10.17487/RFC7838,
April 2016, <https://www.rfc-editor.org/info/rfc7838>. April 2016, <https://www.rfc-editor.org/info/rfc7838>.
[CACHING] Fielding, R., Nottingham, M., and J. Reschke, "HTTP [CACHING] Fielding, R., Nottingham, M., and J. Reschke, "HTTP
Caching", draft-ietf-httpbis-cache-13 (work in progress), Caching", draft-ietf-httpbis-cache-14 (work in progress),
December 2020. January 2021.
[HTTP-REPLAY] [HTTP-REPLAY]
Thomson, M., Nottingham, M., and W. Tarreau, "Using Early Thomson, M., Nottingham, M., and W. Tarreau, "Using Early
Data in HTTP", RFC 8470, DOI 10.17487/RFC8470, September Data in HTTP", RFC 8470, DOI 10.17487/RFC8470, September
2018, <https://www.rfc-editor.org/info/rfc8470>. 2018, <https://www.rfc-editor.org/info/rfc8470>.
[QPACK] Krasic, C., Bishop, M., and A. Frindell, Ed., "QPACK: [QPACK] Krasic, C., Bishop, M., and A. Frindell, Ed., "QPACK:
Header Compression for HTTP over QUIC", draft-ietf-quic- Header Compression for HTTP over QUIC", draft-ietf-quic-
qpack-20 (work in progress). qpack-latest (work in progress).
[QUIC-TRANSPORT] [QUIC-TRANSPORT]
Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", draft-ietf-quic- Multiplexed and Secure Transport", draft-ietf-quic-
transport-33 (work in progress). transport-latest (work in progress).
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, [RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981, RFC 793, DOI 10.17487/RFC0793, September 1981,
<https://www.rfc-editor.org/info/rfc793>. <https://www.rfc-editor.org/info/rfc793>.
[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>.
[RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS) [RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS)
Extensions: Extension Definitions", RFC 6066, Extensions: Extension Definitions", RFC 6066,
DOI 10.17487/RFC6066, January 2011, DOI 10.17487/RFC6066, January 2011,
<https://www.rfc-editor.org/info/rfc6066>. <https://www.rfc-editor.org/info/rfc6066>.
[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
Verification of Domain-Based Application Service Identity
within Internet Public Key Infrastructure Using X.509
(PKIX) Certificates in the Context of Transport Layer
Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March
2011, <https://www.rfc-editor.org/info/rfc6125>.
[RFC6265] Barth, A., "HTTP State Management Mechanism", RFC 6265, [RFC6265] Barth, A., "HTTP State Management Mechanism", RFC 6265,
DOI 10.17487/RFC6265, April 2011, DOI 10.17487/RFC6265, April 2011,
<https://www.rfc-editor.org/info/rfc6265>. <https://www.rfc-editor.org/info/rfc6265>.
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol "Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301, Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, <https://www.rfc-editor.org/info/rfc7301>. July 2014, <https://www.rfc-editor.org/info/rfc7301>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[SEMANTICS] [SEMANTICS]
Fielding, R., Nottingham, M., and J. Reschke, "HTTP Fielding, R., Nottingham, M., and J. Reschke, "HTTP
Semantics", draft-ietf-httpbis-semantics-13 (work in Semantics", draft-ietf-httpbis-semantics-14 (work in
progress), December 2020. progress), January 2021.
[URI] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [URI] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>. <https://www.rfc-editor.org/info/rfc3986>.
12.2. Informative References 12.2. Informative References
[BREACH] Gluck, Y., Harris, N., and A. Prado, "BREACH: Reviving the [BREACH] Gluck, Y., Harris, N., and A. Prado, "BREACH: Reviving the
CRIME Attack", July 2013, CRIME Attack", July 2013,
<http://breachattack.com/resources/ <http://breachattack.com/resources/
BREACH%20-%20SSL,%20gone%20in%2030%20seconds.pdf>. BREACH%20-%20SSL,%20gone%20in%2030%20seconds.pdf>.
[DNS-TERMS]
Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499,
January 2019, <https://www.rfc-editor.org/info/rfc8499>.
[HPACK] Peon, R. and H. Ruellan, "HPACK: Header Compression for [HPACK] Peon, R. and H. Ruellan, "HPACK: Header Compression for
HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015, HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015,
<https://www.rfc-editor.org/info/rfc7541>. <https://www.rfc-editor.org/info/rfc7541>.
[HTTP11] Fielding, R., Nottingham, M., and J. Reschke, "HTTP/1.1", [HTTP11] Fielding, R., Nottingham, M., and J. Reschke, "HTTP/1.1",
draft-ietf-httpbis-messaging-13 (work in progress), draft-ietf-httpbis-messaging-14 (work in progress),
December 2020. January 2021.
[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>.
[RFC6585] Nottingham, M. and R. Fielding, "Additional HTTP Status [RFC6585] Nottingham, M. and R. Fielding, "Additional HTTP Status
Codes", RFC 6585, DOI 10.17487/RFC6585, April 2012, Codes", RFC 6585, DOI 10.17487/RFC6585, April 2012,
<https://www.rfc-editor.org/info/rfc6585>. <https://www.rfc-editor.org/info/rfc6585>.
skipping to change at page 56, line 29 skipping to change at page 57, line 29
HTTP/3 begins from the premise that similarity to HTTP/2 is HTTP/3 begins from the premise that similarity to HTTP/2 is
preferable, but not a hard requirement. HTTP/3 departs from HTTP/2 preferable, but not a hard requirement. HTTP/3 departs from HTTP/2
where QUIC differs from TCP, either to take advantage of QUIC where QUIC differs from TCP, either to take advantage of QUIC
features (like streams) or to accommodate important shortcomings features (like streams) or to accommodate important shortcomings
(such as a lack of total ordering). These differences make HTTP/3 (such as a lack of total ordering). These differences make HTTP/3
similar to HTTP/2 in key aspects, such as the relationship of similar to HTTP/2 in key aspects, such as the relationship of
requests and responses to streams. However, the details of the requests and responses to streams. However, the details of the
HTTP/3 design are substantially different from HTTP/2. HTTP/3 design are substantially different from HTTP/2.
These departures are noted in this section. Some important departures are noted in this section.
A.1. Streams A.1. Streams
HTTP/3 permits use of a larger number of streams (2^62-1) than HTTP/3 permits use of a larger number of streams (2^62-1) than
HTTP/2. The same considerations about exhaustion of stream HTTP/2. The same considerations about exhaustion of stream
identifier space apply, though the space is significantly larger such identifier space apply, though the space is significantly larger such
that it is likely that other limits in QUIC are reached first, such that it is likely that other limits in QUIC are reached first, such
as the limit on the connection flow control window. as the limit on the connection flow control window.
In contrast to HTTP/2, stream concurrency in HTTP/3 is managed by In contrast to HTTP/2, stream concurrency in HTTP/3 is managed by
QUIC. QUIC considers a stream closed when all data has been received QUIC. QUIC considers a stream closed when all data has been received
and sent data has been acknowledged by the peer. HTTP/2 considers a and sent data has been acknowledged by the peer. HTTP/2 considers a
stream closed when the frame containing the END_STREAM bit has been stream closed when the frame containing the END_STREAM bit has been
committed to the transport. As a result, the stream for an committed to the transport. As a result, the stream for an
equivalent exchange could remain "active" for a longer period of equivalent exchange could remain "active" for a longer period of
time. HTTP/3 servers might choose to permit a larger number of time. HTTP/3 servers might choose to permit a larger number of
concurrent client-initiated bidirectional streams to achieve concurrent client-initiated bidirectional streams to achieve
equivalent concurrency to HTTP/2, depending on the expected usage equivalent concurrency to HTTP/2, depending on the expected usage
patterns. patterns.
In HTTP/2, only request and response bodies (the frame payload of
DATA frames) are subject to flow control. All HTTP/3 frames are sent
on QUIC streams, so all frames on all streams are flow-controlled in
HTTP/3.
Due to the presence of other unidirectional stream types, HTTP/3 does Due to the presence of other unidirectional stream types, HTTP/3 does
not rely exclusively on the number of concurrent unidirectional not rely exclusively on the number of concurrent unidirectional
streams to control the number of concurrent in-flight pushes. streams to control the number of concurrent in-flight pushes.
Instead, HTTP/3 clients use the MAX_PUSH_ID frame to control the Instead, HTTP/3 clients use the MAX_PUSH_ID frame to control the
number of pushes received from an HTTP/3 server. number of pushes received from an HTTP/3 server.
A.2. HTTP Frame Types A.2. HTTP Frame Types
Many framing concepts from HTTP/2 can be elided on QUIC, because the Many framing concepts from HTTP/2 can be elided on QUIC, because the
transport deals with them. Because frames are already on a stream, transport deals with them. Because frames are already on a stream,
they can omit the stream number. Because frames do not block they can omit the stream number. Because frames do not block
multiplexing (QUIC's multiplexing occurs below this layer), the multiplexing (QUIC's multiplexing occurs below this layer), the
support for variable-maximum-length packets can be removed. Because support for variable-maximum-length packets can be removed. Because
stream termination is handled by QUIC, an END_STREAM flag is not stream termination is handled by QUIC, an END_STREAM flag is not
required. This permits the removal of the Flags field from the required. This permits the removal of the Flags field from the
generic frame layout. generic frame layout.
Frame payloads are largely drawn from [HTTP2]. However, QUIC Frame payloads are largely drawn from [HTTP2]. However, QUIC
includes many features (e.g., flow control) that are also present in includes many features (e.g., flow control) that are also present in
HTTP/2. In these cases, the HTTP mapping does not re-implement them. HTTP/2. In these cases, the HTTP mapping does not re-implement them.
As a result, several HTTP/2 frame types are not required in HTTP/3. As a result, several HTTP/2 frame types are not required in HTTP/3.
Where an HTTP/2-defined frame is no longer used, the frame ID has Where an HTTP/2-defined frame is no longer used, the frame ID has
been reserved in order to maximize portability between HTTP/2 and been reserved in order to maximize portability between HTTP/2 and
HTTP/3 implementations. However, even equivalent frames between the HTTP/3 implementations. However, even frame types that appear in
two mappings are not identical. both mappings do not have identical semantics.
Many of the differences arise from the fact that HTTP/2 provides an Many of the differences arise from the fact that HTTP/2 provides an
absolute ordering between frames across all streams, while QUIC absolute ordering between frames across all streams, while QUIC
provides this guarantee on each stream only. As a result, if a frame provides this guarantee on each stream only. As a result, if a frame
type makes assumptions that frames from different streams will still type makes assumptions that frames from different streams will still
be received in the order sent, HTTP/3 will break them. be received in the order sent, HTTP/3 will break them.
Some examples of feature adaptations are described below, as well as Some examples of feature adaptations are described below, as well as
general guidance to extension frame implementors converting an HTTP/2 general guidance to extension frame implementors converting an HTTP/2
extension to HTTP/3. extension to HTTP/3.
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is subject to flow control. QUIC provides flow control for stream is subject to flow control. QUIC provides flow control for stream
data and all HTTP/3 frame types defined in this document are sent on data and all HTTP/3 frame types defined in this document are sent on
streams. Therefore, all frame headers and payload are subject to streams. Therefore, all frame headers and payload are subject to
flow control. flow control.
A.2.4. Guidance for New Frame Type Definitions A.2.4. Guidance for New Frame Type Definitions
Frame type definitions in HTTP/3 often use the QUIC variable-length Frame type definitions in HTTP/3 often use the QUIC variable-length
integer encoding. In particular, Stream IDs use this encoding, which integer encoding. In particular, Stream IDs use this encoding, which
allows for a larger range of possible values than the encoding used allows for a larger range of possible values than the encoding used
in HTTP/2. Some frames in HTTP/3 use an identifier rather than a in HTTP/2. Some frames in HTTP/3 use an identifier other than a
Stream ID (e.g., Push IDs). Redefinition of the encoding of Stream ID (e.g., Push IDs). Redefinition of the encoding of
extension frame types might be necessary if the encoding includes a extension frame types might be necessary if the encoding includes a
Stream ID. Stream ID.
Because the Flags field is not present in generic HTTP/3 frames, Because the Flags field is not present in generic HTTP/3 frames,
those frames that depend on the presence of flags need to allocate those frames that depend on the presence of flags need to allocate
space for flags as part of their frame payload. space for flags as part of their frame payload.
Other than these issues, frame type HTTP/2 extensions are typically Other than these issues, frame type HTTP/2 extensions are typically
portable to QUIC simply by replacing Stream 0 in HTTP/2 with a portable to QUIC simply by replacing Stream 0 in HTTP/2 with a
control stream in HTTP/3. HTTP/3 extensions will not assume control stream in HTTP/3. HTTP/3 extensions will not assume
ordering, but would not be harmed by ordering, and would be portable ordering, but would not be harmed by ordering, and are expected to be
to HTTP/2 in the same manner. portable to HTTP/2.
A.2.5. Mapping Between HTTP/2 and HTTP/3 Frame Types A.2.5. Comparison Between HTTP/2 and HTTP/3 Frame Types
DATA (0x0): Padding is not defined in HTTP/3 frames. See DATA (0x0): Padding is not defined in HTTP/3 frames. See
Section 7.2.1. Section 7.2.1.
HEADERS (0x1): The PRIORITY region of HEADERS is not defined in HEADERS (0x1): The PRIORITY region of HEADERS is not defined in
HTTP/3 frames. Padding is not defined in HTTP/3 frames. See HTTP/3 frames. Padding is not defined in HTTP/3 frames. See
Section 7.2.2. Section 7.2.2.
PRIORITY (0x2): As described in Appendix A.2.1, HTTP/3 does not PRIORITY (0x2): As described in Appendix A.2.1, HTTP/3 does not
provide a means of signaling priority. provide a means of signaling priority.
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A.3. HTTP/2 SETTINGS Parameters A.3. HTTP/2 SETTINGS Parameters
An important difference from HTTP/2 is that settings are sent once, An important difference from HTTP/2 is that settings are sent once,
as the first frame of the control stream, and thereafter cannot as the first frame of the control stream, and thereafter cannot
change. This eliminates many corner cases around synchronization of change. This eliminates many corner cases around synchronization of
changes. changes.
Some transport-level options that HTTP/2 specifies via the SETTINGS Some transport-level options that HTTP/2 specifies via the SETTINGS
frame are superseded by QUIC transport parameters in HTTP/3. The frame are superseded by QUIC transport parameters in HTTP/3. The
HTTP-level options that are retained in HTTP/3 have the same value as HTTP-level setting that is retained in HTTP/3 has the same value as
in HTTP/2. The superseded settings are reserved, and their receipt in HTTP/2. The superseded settings are reserved, and their receipt
is an error. See Section 7.2.4.1 for discussion of both the retained is an error. See Section 7.2.4.1 for discussion of both the retained
and reserved values. and reserved values.
Below is a listing of how each HTTP/2 SETTINGS parameter is mapped: Below is a listing of how each HTTP/2 SETTINGS parameter is mapped:
SETTINGS_HEADER_TABLE_SIZE: See [QPACK]. SETTINGS_HEADER_TABLE_SIZE (0x1): See [QPACK].
SETTINGS_ENABLE_PUSH: This is removed in favor of the MAX_PUSH_ID SETTINGS_ENABLE_PUSH (0x2): This is removed in favor of the
frame, which provides a more granular control over server push. MAX_PUSH_ID frame, which provides a more granular control over
Specifying a setting with the identifier 0x2 (corresponding to the server push. Specifying a setting with the identifier 0x2
SETTINGS_ENABLE_PUSH parameter) in the HTTP/3 SETTINGS frame is an (corresponding to the SETTINGS_ENABLE_PUSH parameter) in the
error. HTTP/3 SETTINGS frame is an error.
SETTINGS_MAX_CONCURRENT_STREAMS: QUIC controls the largest open SETTINGS_MAX_CONCURRENT_STREAMS (0x3): QUIC controls the largest
Stream ID as part of its flow control logic. Specifying a setting open Stream ID as part of its flow control logic. Specifying a
with the identifier 0x3 (corresponding to the setting with the identifier 0x3 (corresponding to the
SETTINGS_MAX_CONCURRENT_STREAMS parameter) in the HTTP/3 SETTINGS SETTINGS_MAX_CONCURRENT_STREAMS parameter) in the HTTP/3 SETTINGS
frame is an error. frame is an error.
SETTINGS_INITIAL_WINDOW_SIZE: QUIC requires both stream and SETTINGS_INITIAL_WINDOW_SIZE (0x4): QUIC requires both stream and
connection flow control window sizes to be specified in the connection flow control window sizes to be specified in the
initial transport handshake. Specifying a setting with the initial transport handshake. Specifying a setting with the
identifier 0x4 (corresponding to the SETTINGS_INITIAL_WINDOW_SIZE identifier 0x4 (corresponding to the SETTINGS_INITIAL_WINDOW_SIZE
parameter) in the HTTP/3 SETTINGS frame is an error. parameter) in the HTTP/3 SETTINGS frame is an error.
SETTINGS_MAX_FRAME_SIZE: This setting has no equivalent in HTTP/3. SETTINGS_MAX_FRAME_SIZE (0x5): This setting has no equivalent in
Specifying a setting with the identifier 0x5 (corresponding to the HTTP/3. Specifying a setting with the identifier 0x5
SETTINGS_MAX_FRAME_SIZE parameter) in the HTTP/3 SETTINGS frame is (corresponding to the SETTINGS_MAX_FRAME_SIZE parameter) in the
an error. HTTP/3 SETTINGS frame is an error.
SETTINGS_MAX_HEADER_LIST_SIZE: This setting identifier has been SETTINGS_MAX_HEADER_LIST_SIZE (0x6): This setting identifier has
renamed SETTINGS_MAX_FIELD_SECTION_SIZE. been renamed SETTINGS_MAX_FIELD_SECTION_SIZE.
In HTTP/3, setting values are variable-length integers (6, 14, 30, or In HTTP/3, setting values are variable-length integers (6, 14, 30, or
62 bits long) rather than fixed-length 32-bit fields as in HTTP/2. 62 bits long) rather than fixed-length 32-bit fields as in HTTP/2.
This will often produce a shorter encoding, but can produce a longer This will often produce a shorter encoding, but can produce a longer
encoding for settings that use the full 32-bit space. Settings encoding for settings that use the full 32-bit space. Settings
ported from HTTP/2 might choose to redefine their value to limit it ported from HTTP/2 might choose to redefine their value to limit it
to 30 bits for more efficient encoding, or to make use of the 62-bit to 30 bits for more efficient encoding, or to make use of the 62-bit
space if more than 30 bits are required. space if more than 30 bits are required.
Settings need to be defined separately for HTTP/2 and HTTP/3. The Settings need to be defined separately for HTTP/2 and HTTP/3. The
skipping to change at page 61, line 30 skipping to change at page 62, line 39
PROTOCOL_ERROR (0x1): This is mapped to H3_GENERAL_PROTOCOL_ERROR PROTOCOL_ERROR (0x1): This is mapped to H3_GENERAL_PROTOCOL_ERROR
except in cases where more specific error codes have been defined. except in cases where more specific error codes have been defined.
Such cases include H3_FRAME_UNEXPECTED, H3_MESSAGE_ERROR, and Such cases include H3_FRAME_UNEXPECTED, H3_MESSAGE_ERROR, and
H3_CLOSED_CRITICAL_STREAM defined in Section 8.1. H3_CLOSED_CRITICAL_STREAM defined in Section 8.1.
INTERNAL_ERROR (0x2): H3_INTERNAL_ERROR in Section 8.1. INTERNAL_ERROR (0x2): H3_INTERNAL_ERROR in Section 8.1.
FLOW_CONTROL_ERROR (0x3): Not applicable, since QUIC handles flow FLOW_CONTROL_ERROR (0x3): Not applicable, since QUIC handles flow
control. control.
SETTINGS_TIMEOUT (0x4): Not applicable, since no acknowledgement of SETTINGS_TIMEOUT (0x4): Not applicable, since no acknowledgment of
SETTINGS is defined. SETTINGS is defined.
STREAM_CLOSED (0x5): Not applicable, since QUIC handles stream STREAM_CLOSED (0x5): Not applicable, since QUIC handles stream
management. management.
FRAME_SIZE_ERROR (0x6): H3_FRAME_ERROR error code defined in FRAME_SIZE_ERROR (0x6): H3_FRAME_ERROR error code defined in
Section 8.1. Section 8.1.
REFUSED_STREAM (0x7): H3_REQUEST_REJECTED (in Section 8.1) is used REFUSED_STREAM (0x7): H3_REQUEST_REJECTED (in Section 8.1) is used
to indicate that a request was not processed. Otherwise, not to indicate that a request was not processed. Otherwise, not
skipping to change at page 71, line 4 skipping to change at page 72, line 9
o Changed from using HTTP/2 framing within Stream 3 to new framing o Changed from using HTTP/2 framing within Stream 3 to new framing
format and two-stream-per-request model (#71,#72,#73) format and two-stream-per-request model (#71,#72,#73)
o Adopted SETTINGS format from draft-bishop-httpbis-extended- o Adopted SETTINGS format from draft-bishop-httpbis-extended-
settings-01 settings-01
o Reworked SETTINGS_ACK to account for indeterminate inter-stream o Reworked SETTINGS_ACK to account for indeterminate inter-stream
order (#75) order (#75)
o Described CONNECT pseudo-method (#95) o Described CONNECT pseudo-method (#95)
o Updated ALPN token and Alt-Svc guidance (#13,#87) o Updated ALPN token and Alt-Svc guidance (#13,#87)
o Application-layer-defined error codes (#19,#74) o Application-layer-defined error codes (#19,#74)
B.34. Since draft-shade-quic-http2-mapping-00 B.34. Since draft-shade-quic-http2-mapping-00
o Adopted as base for draft-ietf-quic-http o Adopted as base for draft-ietf-quic-http
o Updated authors/editors list o Updated authors/editors list
Acknowledgements Acknowledgments
The original authors of this specification were Robbie Shade and Mike The original authors of this specification were Robbie Shade and Mike
Warres. Warres.
The IETF QUIC Working Group received an enormous amount of support The IETF QUIC Working Group received an enormous amount of support
from many people. Among others, the following people provided from many people. Among others, the following people provided
substantial contributions to this document: substantial contributions to this document:
o Bence Beky o Bence Beky
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