draft-ietf-quic-http-27.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 February 21, 2020 Intended status: Standards Track April 10, 2020
Expires: August 24, 2020 Expires: October 12, 2020
Hypertext Transfer Protocol Version 3 (HTTP/3) Hypertext Transfer Protocol Version 3 (HTTP/3)
draft-ietf-quic-http-27 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 1, line 45 skipping to change at page 1, line 45
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 24, 2020. This Internet-Draft will expire on October 12, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 27 skipping to change at page 2, line 27
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Prior versions of HTTP . . . . . . . . . . . . . . . . . 4 1.1. Prior versions of HTTP . . . . . . . . . . . . . . . . . 4
1.2. Delegation to QUIC . . . . . . . . . . . . . . . . . . . 5 1.2. Delegation to QUIC . . . . . . . . . . . . . . . . . . . 5
2. HTTP/3 Protocol Overview . . . . . . . . . . . . . . . . . . 5 2. HTTP/3 Protocol Overview . . . . . . . . . . . . . . . . . . 5
2.1. Document Organization . . . . . . . . . . . . . . . . . . 6 2.1. Document Organization . . . . . . . . . . . . . . . . . . 6
2.2. Conventions and Terminology . . . . . . . . . . . . . . . 6 2.2. Conventions and Terminology . . . . . . . . . . . . . . . 7
3. Connection Setup and Management . . . . . . . . . . . . . . . 8 3. Connection Setup and Management . . . . . . . . . . . . . . . 8
3.1. Draft Version Identification . . . . . . . . . . . . . . 8 3.1. Draft Version Identification . . . . . . . . . . . . . . 8
3.2. Discovering an HTTP/3 Endpoint . . . . . . . . . . . . . 8 3.2. Discovering an HTTP/3 Endpoint . . . . . . . . . . . . . 9
3.3. Connection Establishment . . . . . . . . . . . . . . . . 9 3.3. Connection Establishment . . . . . . . . . . . . . . . . 9
3.4. Connection Reuse . . . . . . . . . . . . . . . . . . . . 9 3.4. Connection Reuse . . . . . . . . . . . . . . . . . . . . 10
4. HTTP Request Lifecycle . . . . . . . . . . . . . . . . . . . 10 4. HTTP Request Lifecycle . . . . . . . . . . . . . . . . . . . 11
4.1. HTTP Message Exchanges . . . . . . . . . . . . . . . . . 10 4.1. HTTP Message Exchanges . . . . . . . . . . . . . . . . . 11
4.1.1. Header Formatting and Compression . . . . . . . . . . 12 4.1.1. Field Formatting and Compression . . . . . . . . . . 13
4.1.2. Request Cancellation and Rejection . . . . . . . . . 15 4.1.2. Request Cancellation and Rejection . . . . . . . . . 16
4.1.3. Malformed Requests and Responses . . . . . . . . . . 16 4.1.3. Malformed Requests and Responses . . . . . . . . . . 17
4.2. The CONNECT Method . . . . . . . . . . . . . . . . . . . 17 4.2. The CONNECT Method . . . . . . . . . . . . . . . . . . . 18
4.3. HTTP Upgrade . . . . . . . . . . . . . . . . . . . . . . 18 4.3. HTTP Upgrade . . . . . . . . . . . . . . . . . . . . . . 19
4.4. Server Push . . . . . . . . . . . . . . . . . . . . . . . 18 4.4. Server Push . . . . . . . . . . . . . . . . . . . . . . . 19
5. Connection Closure . . . . . . . . . . . . . . . . . . . . . 19 5. Connection Closure . . . . . . . . . . . . . . . . . . . . . 21
5.1. Idle Connections . . . . . . . . . . . . . . . . . . . . 19 5.1. Idle Connections . . . . . . . . . . . . . . . . . . . . 21
5.2. Connection Shutdown . . . . . . . . . . . . . . . . . . . 20 5.2. Connection Shutdown . . . . . . . . . . . . . . . . . . . 22
5.3. Immediate Application Closure . . . . . . . . . . . . . . 21 5.3. Immediate Application Closure . . . . . . . . . . . . . . 24
5.4. Transport Closure . . . . . . . . . . . . . . . . . . . . 22 5.4. Transport Closure . . . . . . . . . . . . . . . . . . . . 24
6. Stream Mapping and Usage . . . . . . . . . . . . . . . . . . 22 6. Stream Mapping and Usage . . . . . . . . . . . . . . . . . . 24
6.1. Bidirectional Streams . . . . . . . . . . . . . . . . . . 22 6.1. Bidirectional Streams . . . . . . . . . . . . . . . . . . 25
6.2. Unidirectional Streams . . . . . . . . . . . . . . . . . 23 6.2. Unidirectional Streams . . . . . . . . . . . . . . . . . 25
6.2.1. Control Streams . . . . . . . . . . . . . . . . . . . 24 6.2.1. Control Streams . . . . . . . . . . . . . . . . . . . 26
6.2.2. Push Streams . . . . . . . . . . . . . . . . . . . . 24 6.2.2. Push Streams . . . . . . . . . . . . . . . . . . . . 27
6.2.3. Reserved Stream Types . . . . . . . . . . . . . . . . 25 6.2.3. Reserved Stream Types . . . . . . . . . . . . . . . . 28
7. HTTP Framing Layer . . . . . . . . . . . . . . . . . . . . . 25 7. HTTP Framing Layer . . . . . . . . . . . . . . . . . . . . . 28
7.1. Frame Layout . . . . . . . . . . . . . . . . . . . . . . 26 7.1. Frame Layout . . . . . . . . . . . . . . . . . . . . . . 29
7.2. Frame Definitions . . . . . . . . . . . . . . . . . . . . 27 7.2. Frame Definitions . . . . . . . . . . . . . . . . . . . . 30
7.2.1. DATA . . . . . . . . . . . . . . . . . . . . . . . . 27 7.2.1. DATA . . . . . . . . . . . . . . . . . . . . . . . . 30
7.2.2. HEADERS . . . . . . . . . . . . . . . . . . . . . . . 28 7.2.2. HEADERS . . . . . . . . . . . . . . . . . . . . . . . 31
7.2.3. CANCEL_PUSH . . . . . . . . . . . . . . . . . . . . . 28 7.2.3. CANCEL_PUSH . . . . . . . . . . . . . . . . . . . . . 31
7.2.4. SETTINGS . . . . . . . . . . . . . . . . . . . . . . 29 7.2.4. SETTINGS . . . . . . . . . . . . . . . . . . . . . . 32
7.2.5. PUSH_PROMISE . . . . . . . . . . . . . . . . . . . . 32 7.2.5. PUSH_PROMISE . . . . . . . . . . . . . . . . . . . . 35
7.2.6. GOAWAY . . . . . . . . . . . . . . . . . . . . . . . 33 7.2.6. GOAWAY . . . . . . . . . . . . . . . . . . . . . . . 36
7.2.7. MAX_PUSH_ID . . . . . . . . . . . . . . . . . . . . . 34 7.2.7. MAX_PUSH_ID . . . . . . . . . . . . . . . . . . . . . 37
7.2.8. Reserved Frame Types . . . . . . . . . . . . . . . . 35 7.2.8. Reserved Frame Types . . . . . . . . . . . . . . . . 38
8. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 35 8. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 38
8.1. HTTP/3 Error Codes . . . . . . . . . . . . . . . . . . . 35 8.1. HTTP/3 Error Codes . . . . . . . . . . . . . . . . . . . 39
9. Extensions to HTTP/3 . . . . . . . . . . . . . . . . . . . . 37 9. Extensions to HTTP/3 . . . . . . . . . . . . . . . . . . . . 40
10. Security Considerations . . . . . . . . . . . . . . . . . . . 38 10. Security Considerations . . . . . . . . . . . . . . . . . . . 41
10.1. Traffic Analysis . . . . . . . . . . . . . . . . . . . . 38 10.1. Server Authority . . . . . . . . . . . . . . . . . . . . 41
10.2. Frame Parsing . . . . . . . . . . . . . . . . . . . . . 38 10.2. Cross-Protocol Attacks . . . . . . . . . . . . . . . . . 41
10.3. Early Data . . . . . . . . . . . . . . . . . . . . . . . 38 10.3. Intermediary Encapsulation Attacks . . . . . . . . . . . 41
10.4. Migration . . . . . . . . . . . . . . . . . . . . . . . 38 10.4. Cacheability of Pushed Responses . . . . . . . . . . . . 42
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39 10.5. Denial-of-Service Considerations . . . . . . . . . . . . 42
11.1. Registration of HTTP/3 Identification String . . . . . . 39 10.5.1. Limits on Field Section Size . . . . . . . . . . . . 43
11.2. New Registries . . . . . . . . . . . . . . . . . . . . . 39 10.5.2. CONNECT Issues . . . . . . . . . . . . . . . . . . . 44
11.2.1. Frame Types . . . . . . . . . . . . . . . . . . . . 39 10.6. Use of Compression . . . . . . . . . . . . . . . . . . . 44
11.2.2. Settings Parameters . . . . . . . . . . . . . . . . 40 10.7. Padding and Traffic Analysis . . . . . . . . . . . . . . 44
11.2.3. Error Codes . . . . . . . . . . . . . . . . . . . . 41 10.8. Frame Parsing . . . . . . . . . . . . . . . . . . . . . 45
11.2.4. Stream Types . . . . . . . . . . . . . . . . . . . . 44 10.9. Early Data . . . . . . . . . . . . . . . . . . . . . . . 45
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 44 10.10. Migration . . . . . . . . . . . . . . . . . . . . . . . 45
12.1. Normative References . . . . . . . . . . . . . . . . . . 44 10.11. Privacy Considerations . . . . . . . . . . . . . . . . . 45
12.2. Informative References . . . . . . . . . . . . . . . . . 46 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46
12.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 47 11.1. Registration of HTTP/3 Identification String . . . . . . 46
Appendix A. Considerations for Transitioning from HTTP/2 . . . . 47 11.2. New Registries . . . . . . . . . . . . . . . . . . . . . 46
A.1. Streams . . . . . . . . . . . . . . . . . . . . . . . . . 47 11.2.1. Frame Types . . . . . . . . . . . . . . . . . . . . 46
A.2. HTTP Frame Types . . . . . . . . . . . . . . . . . . . . 48 11.2.2. Settings Parameters . . . . . . . . . . . . . . . . 48
A.2.1. Prioritization Differences . . . . . . . . . . . . . 48 11.2.3. Error Codes . . . . . . . . . . . . . . . . . . . . 49
A.2.2. Header Compression Differences . . . . . . . . . . . 49 11.2.4. Stream Types . . . . . . . . . . . . . . . . . . . . 51
A.2.3. Guidance for New Frame Type Definitions . . . . . . . 49 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 52
A.2.4. Mapping Between HTTP/2 and HTTP/3 Frame Types . . . . 49 12.1. Normative References . . . . . . . . . . . . . . . . . . 52
A.3. HTTP/2 SETTINGS Parameters . . . . . . . . . . . . . . . 50 12.2. Informative References . . . . . . . . . . . . . . . . . 54
A.4. HTTP/2 Error Codes . . . . . . . . . . . . . . . . . . . 51 12.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 52 Appendix A. Considerations for Transitioning from HTTP/2 . . . . 55
B.1. Since draft-ietf-quic-http-26 . . . . . . . . . . . . . . 52 A.1. Streams . . . . . . . . . . . . . . . . . . . . . . . . . 55
B.2. Since draft-ietf-quic-http-25 . . . . . . . . . . . . . . 53 A.2. HTTP Frame Types . . . . . . . . . . . . . . . . . . . . 56
B.3. Since draft-ietf-quic-http-24 . . . . . . . . . . . . . . 53 A.2.1. Prioritization Differences . . . . . . . . . . . . . 56
B.4. Since draft-ietf-quic-http-23 . . . . . . . . . . . . . . 53 A.2.2. Field Compression Differences . . . . . . . . . . . . 57
B.5. Since draft-ietf-quic-http-22 . . . . . . . . . . . . . . 53 A.2.3. Guidance for New Frame Type Definitions . . . . . . . 57
B.6. Since draft-ietf-quic-http-21 . . . . . . . . . . . . . . 54 A.2.4. Mapping Between HTTP/2 and HTTP/3 Frame Types . . . . 57
B.7. Since draft-ietf-quic-http-20 . . . . . . . . . . . . . . 54 A.3. HTTP/2 SETTINGS Parameters . . . . . . . . . . . . . . . 58
B.8. Since draft-ietf-quic-http-19 . . . . . . . . . . . . . . 55 A.4. HTTP/2 Error Codes . . . . . . . . . . . . . . . . . . . 59
B.9. Since draft-ietf-quic-http-18 . . . . . . . . . . . . . . 55 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 60
B.10. Since draft-ietf-quic-http-17 . . . . . . . . . . . . . . 56 B.1. Since draft-ietf-quic-http-26 . . . . . . . . . . . . . . 61
B.11. Since draft-ietf-quic-http-16 . . . . . . . . . . . . . . 56 B.2. Since draft-ietf-quic-http-25 . . . . . . . . . . . . . . 61
B.12. Since draft-ietf-quic-http-15 . . . . . . . . . . . . . . 56 B.3. Since draft-ietf-quic-http-24 . . . . . . . . . . . . . . 61
B.13. Since draft-ietf-quic-http-14 . . . . . . . . . . . . . . 56 B.4. Since draft-ietf-quic-http-23 . . . . . . . . . . . . . . 61
B.14. Since draft-ietf-quic-http-13 . . . . . . . . . . . . . . 57 B.5. Since draft-ietf-quic-http-22 . . . . . . . . . . . . . . 61
B.15. Since draft-ietf-quic-http-12 . . . . . . . . . . . . . . 57 B.6. Since draft-ietf-quic-http-21 . . . . . . . . . . . . . . 62
B.16. Since draft-ietf-quic-http-11 . . . . . . . . . . . . . . 57 B.7. Since draft-ietf-quic-http-20 . . . . . . . . . . . . . . 62
B.17. Since draft-ietf-quic-http-10 . . . . . . . . . . . . . . 57 B.8. Since draft-ietf-quic-http-19 . . . . . . . . . . . . . . 63
B.18. Since draft-ietf-quic-http-09 . . . . . . . . . . . . . . 57 B.9. Since draft-ietf-quic-http-18 . . . . . . . . . . . . . . 63
B.19. Since draft-ietf-quic-http-08 . . . . . . . . . . . . . . 58 B.10. Since draft-ietf-quic-http-17 . . . . . . . . . . . . . . 64
B.20. Since draft-ietf-quic-http-07 . . . . . . . . . . . . . . 58 B.11. Since draft-ietf-quic-http-16 . . . . . . . . . . . . . . 64
B.21. Since draft-ietf-quic-http-06 . . . . . . . . . . . . . . 58 B.12. Since draft-ietf-quic-http-15 . . . . . . . . . . . . . . 64
B.22. Since draft-ietf-quic-http-05 . . . . . . . . . . . . . . 58 B.13. Since draft-ietf-quic-http-14 . . . . . . . . . . . . . . 64
B.23. Since draft-ietf-quic-http-04 . . . . . . . . . . . . . . 58 B.14. Since draft-ietf-quic-http-13 . . . . . . . . . . . . . . 65
B.24. Since draft-ietf-quic-http-03 . . . . . . . . . . . . . . 59 B.15. Since draft-ietf-quic-http-12 . . . . . . . . . . . . . . 65
B.25. Since draft-ietf-quic-http-02 . . . . . . . . . . . . . . 59 B.16. Since draft-ietf-quic-http-11 . . . . . . . . . . . . . . 65
B.26. Since draft-ietf-quic-http-01 . . . . . . . . . . . . . . 59 B.17. Since draft-ietf-quic-http-10 . . . . . . . . . . . . . . 65
B.27. Since draft-ietf-quic-http-00 . . . . . . . . . . . . . . 59 B.18. Since draft-ietf-quic-http-09 . . . . . . . . . . . . . . 66
B.28. Since draft-shade-quic-http2-mapping-00 . . . . . . . . . 60 B.19. Since draft-ietf-quic-http-08 . . . . . . . . . . . . . . 66
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 60 B.20. Since draft-ietf-quic-http-07 . . . . . . . . . . . . . . 66
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 60 B.21. Since draft-ietf-quic-http-06 . . . . . . . . . . . . . . 66
B.22. Since draft-ietf-quic-http-05 . . . . . . . . . . . . . . 66
B.23. Since draft-ietf-quic-http-04 . . . . . . . . . . . . . . 66
B.24. Since draft-ietf-quic-http-03 . . . . . . . . . . . . . . 67
B.25. Since draft-ietf-quic-http-02 . . . . . . . . . . . . . . 67
B.26. Since draft-ietf-quic-http-01 . . . . . . . . . . . . . . 67
B.27. Since draft-ietf-quic-http-00 . . . . . . . . . . . . . . 67
B.28. Since draft-shade-quic-http2-mapping-00 . . . . . . . . . 68
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 68
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 68
1. Introduction 1. Introduction
HTTP semantics are used for a broad range of services on the HTTP semantics [SEMANTICS] are used for a broad range of services on
Internet. These semantics have commonly been used with two different the Internet. These semantics have most commonly been used with two
TCP mappings, HTTP/1.1 and HTTP/2. HTTP/3 supports the same different TCP mappings, HTTP/1.1 and HTTP/2. HTTP/3 supports the
semantics over a new transport protocol, QUIC. same semantics over a new transport protocol, QUIC.
1.1. Prior versions of HTTP 1.1. Prior versions of HTTP
HTTP/1.1 is a TCP mapping which uses whitespace-delimited text fields HTTP/1.1 [HTTP11] is a TCP mapping which uses whitespace-delimited
to convey HTTP messages. While these exchanges are human-readable, text fields to convey HTTP messages. While these exchanges are
using whitespace for message formatting leads to parsing difficulties human-readable, using whitespace for message formatting leads to
and workarounds to be tolerant of variant behavior. Because each parsing complexity and motivates tolerance of variant behavior.
connection can transfer only a single HTTP request or response at a Because each connection can transfer only a single HTTP request or
time in each direction, multiple parallel TCP connections are often response at a time in each direction, multiple parallel TCP
used, reducing the ability of the congestion controller to accurately connections are often used, reducing the ability of the congestion
manage traffic between endpoints. controller to effectively manage traffic between endpoints.
HTTP/2 introduced a binary framing and multiplexing layer to improve HTTP/2 [HTTP2] introduced a binary framing and multiplexing layer to
latency without modifying the transport layer. However, because the improve latency without modifying the transport layer. However,
parallel nature of HTTP/2's multiplexing is not visible to TCP's loss because the parallel nature of HTTP/2's multiplexing is not visible
recovery mechanisms, a lost or reordered packet causes all active to TCP's loss recovery mechanisms, a lost or reordered packet causes
transactions to experience a stall regardless of whether that all active transactions to experience a stall regardless of whether
transaction was 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, it has the capability to control across the entire connection, it 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 at the transport layer, offering comparable incorporates TLS 1.3 [TLS13] at the transport layer, offering
security to running TLS over TCP, with the improved connection setup comparable security to running TLS over TCP, with the improved
latency of TCP Fast Open [RFC7413]. connection setup latency of TCP Fast Open [TFO].
This document defines a mapping of HTTP semantics over the QUIC This document defines a mapping of HTTP semantics over the QUIC
transport protocol, drawing heavily on the design of HTTP/2. While transport protocol, drawing heavily on the design of HTTP/2. While
delegating stream lifetime and flow control issues to QUIC, a similar delegating stream lifetime and flow control issues to QUIC, a similar
binary framing is used on each stream. Some HTTP/2 features are binary framing is used on each stream. Some HTTP/2 features are
subsumed by QUIC, while other features are implemented atop QUIC. 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].
skipping to change at page 6, line 5 skipping to change at page 6, line 12
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] which Server push is an interaction mode introduced in HTTP/2 [HTTP2] which
permits a server to push a request-response exchange to a client in permits a server to push a request-response exchange to a client in
anticipation of the client making the indicated request. This trades anticipation of the client making the indicated request. This trades
off network usage against a potential latency gain. Several HTTP/3 off network usage against a potential latency gain. Several HTTP/3
frames are used to manage server push, such as PUSH_PROMISE, frames are used to manage server push, such as PUSH_PROMISE,
MAX_PUSH_ID, and CANCEL_PUSH. MAX_PUSH_ID, and CANCEL_PUSH.
As in HTTP/2, request and response headers are compressed for As in HTTP/2, request and response fields are compressed for
transmission. Because HPACK [HPACK] relies on in-order transmission transmission. Because HPACK [HPACK] relies on in-order transmission
of compressed header blocks (a guarantee not provided by QUIC), of compressed field sections (a guarantee not provided by QUIC),
HTTP/3 replaces HPACK with QPACK [QPACK]. QPACK uses separate HTTP/3 replaces HPACK with QPACK [QPACK]. QPACK uses separate
unidirectional streams to modify and track header table state, while unidirectional streams to modify and track field table state, while
header blocks refer to the state of the table without modifying it. encoded field sections refer to the state of the table without
modifying it.
2.1. Document Organization 2.1. Document Organization
The following sections provide a detailed overview of the connection The following sections provide a detailed overview of the connection
lifecycle and key concepts: lifecycle and key concepts:
o Connection Setup and Management (Section 3) covers how an HTTP/3 o Connection Setup and Management (Section 3) covers how an HTTP/3
endpoint is discovered and a connection is established. endpoint is discovered and a connection is established.
o HTTP Request Lifecycle (Section 4) describes how HTTP semantics o HTTP Request Lifecycle (Section 4) describes how HTTP semantics
skipping to change at page 8, line 7 skipping to change at page 8, line 15
sender: An endpoint that is transmitting frames. sender: An endpoint that is transmitting frames.
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. QUIC transport.
stream error: An error on the individual HTTP/3 stream. stream error: An error on the individual HTTP/3 stream.
The term "payload body" is defined in Section 3.3 of [RFC7230]. The term "payload body" is defined in Section 6.3.3 of [SEMANTICS].
Finally, the terms "gateway", "intermediary", "proxy", and "tunnel" Finally, the terms "gateway", "intermediary", "proxy", and "tunnel"
are defined in Section 2.3 of [RFC7230]. Intermediaries act as both are defined in Section 2.2 of [SEMANTICS]. Intermediaries act as
client and server at different times. both client and server at different times.
3. Connection Setup and Management 3. Connection Setup and Management
3.1. Draft Version Identification 3.1. Draft Version Identification
*RFC Editor's Note:* Please remove this section prior to *RFC Editor's Note:* Please remove this section prior to
publication of a final version of this document. publication of a final version of this document.
HTTP/3 uses the token "h3" to identify itself in ALPN and Alt-Svc. HTTP/3 uses the token "h3" to identify itself in ALPN and Alt-Svc.
Only implementations of the final, published RFC can identify Only implementations of the final, published RFC can identify
skipping to change at page 8, line 41 skipping to change at page 8, line 49
their transport. For example, the application protocol defined in their transport. For example, the application protocol defined in
draft-ietf-quic-http-25 uses the transport defined in draft-ietf- draft-ietf-quic-http-25 uses the transport defined in draft-ietf-
quic-transport-25. quic-transport-25.
Non-compatible experiments that are based on these draft versions Non-compatible experiments that are based on these draft versions
MUST append the string "-" and an experiment name to the identifier. MUST append the string "-" and an experiment name to the identifier.
For example, an experimental implementation based on draft-ietf-quic- For example, an experimental implementation based on draft-ietf-quic-
http-09 which reserves an extra stream for unsolicited transmission http-09 which reserves an extra stream for unsolicited transmission
of 1980s pop music might identify itself as "h3-09-rickroll". Note of 1980s pop music might identify itself as "h3-09-rickroll". Note
that any label MUST conform to the "token" syntax defined in that any label MUST conform to the "token" syntax defined in
Section 3.2.6 of [RFC7230]. Experimenters are encouraged to Section 4.4.1.1 of [SEMANTICS]. Experimenters are encouraged to
coordinate their experiments on the quic@ietf.org mailing list. coordinate their experiments on the quic@ietf.org mailing list.
3.2. Discovering an HTTP/3 Endpoint 3.2. Discovering an HTTP/3 Endpoint
An HTTP origin advertises the availability of an equivalent HTTP/3 An HTTP origin advertises 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 ALPN token defined in Section 3.3. ALTSVC frame ([ALTSVC]), using the ALPN token defined in Section 3.3.
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
skipping to change at page 9, line 48 skipping to change at page 10, line 9
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
established, a SETTINGS frame (Section 7.2.4) MUST be sent by each established, a SETTINGS frame (Section 7.2.4) MUST be sent by each
endpoint as the initial frame of their respective HTTP control stream endpoint as the initial frame of their respective HTTP control stream
(see Section 6.2.1). (see Section 6.2.1).
3.4. Connection Reuse 3.4. Connection Reuse
HTTP/3 connections are persistent across multiple requests. For best
performance, it is expected that clients will not close connections
until it is determined that no further communication with a server is
necessary (for example, when a user navigates away from a particular
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.
The client MAY send any requests for which the client considers the The client MAY send any requests for which the client considers the
server authoritative. server authoritative.
An authoritative HTTP/3 endpoint is typically discovered because the An authoritative HTTP/3 endpoint is typically discovered because the
client has received an Alt-Svc record from the request's origin which client has received an Alt-Svc record from the request's origin which
nominates the endpoint as a valid HTTP Alternative Service for that nominates the endpoint as a valid HTTP Alternative Service for that
origin. As required by [RFC7838], clients MUST check that the origin. As required by [RFC7838], clients MUST check that the
nominated server can present a valid certificate for the origin nominated server can present a valid certificate for the origin
before considering it authoritative. Clients MUST NOT assume that an before considering it authoritative. Clients MUST NOT assume that an
HTTP/3 endpoint is authoritative for other origins without an HTTP/3 endpoint is authoritative for other origins without an
explicit signal. explicit signal.
Clients SHOULD NOT open more than one HTTP/3 connection to a given
host and port pair, where the host is derived from a URI, a selected
alternative service [ALTSVC], or a configured proxy. A client MAY
open multiple 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.
Prior to making requests for an origin whose scheme is not "https," Prior to making requests for an origin whose scheme is not "https,"
the client MUST ensure the server is willing to serve that scheme. the client MUST ensure the server is willing to serve that scheme.
If the client intends to make requests for an origin whose scheme is If the client intends to make requests for an origin whose scheme is
"http", this means that it MUST obtain a valid "http-opportunistic" "http", this means that it MUST obtain a valid "http-opportunistic"
response for the origin as described in [RFC8164] prior to making any response for the origin as described in [RFC8164] prior to making any
such requests. Other schemes might define other mechanisms. such requests. Other schemes might define other mechanisms.
Servers are encouraged to maintain open connections for as long as
possible but are permitted to terminate idle connections if
necessary. When either endpoint chooses to close the HTTP/3 session,
the terminating endpoint SHOULD first send a GOAWAY frame
(Section 5.2) so that both endpoints can reliably determine whether
previously sent frames have been processed and gracefully complete or
terminate any necessary remaining tasks.
A server that does not wish clients to reuse connections for a A server that does not wish clients to reuse 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 9.1.2 of [HTTP2]).
The considerations discussed in Section 9.1 of [HTTP2] also apply to
the management of HTTP/3 connections.
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 client-initiated bidirectional A client sends an HTTP request on a client-initiated bidirectional
QUIC stream. A client MUST send only a single request on a given QUIC stream. A client MUST send only a single request on a given
stream. A server sends zero or more non-final HTTP responses on the stream. A server sends zero or more interim HTTP responses on the
same stream as the request, followed by a single final HTTP response, same stream as the request, followed by a single final HTTP response,
as detailed below. as detailed below.
Pushed responses are sent on a server-initiated unidirectional QUIC Pushed responses are sent on a server-initiated unidirectional QUIC
stream (see Section 6.2.2). A server sends zero or more non-final stream (see Section 6.2.2). A server sends zero or more interim HTTP
HTTP 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 message header (see Section 3.2 of [RFC7230]), sent as a 1. the header field section (see Section 4 of [SEMANTICS]), sent as
single HEADERS frame (see Section 7.2.2), a single HEADERS frame (see Section 7.2.2),
2. optionally, the payload body, if present (see Section 3.3 of 2. optionally, the payload body, if present (see Section 6.3.3 of
[RFC7230]), sent as a series of DATA frames (see Section 7.2.1), [SEMANTICS]), sent as a series of DATA frames (see
Section 7.2.1),
3. optionally, trailing headers, if present (see Section 4.1.2 of 3. optionally, the trailer field section, if present (see
[RFC7230]), sent as a single HEADERS frame. Section 4.6 of [SEMANTICS]), sent as a single HEADERS frame.
Receipt of DATA and HEADERS frames in any other sequence MUST be Receipt of DATA and HEADERS frames in any other sequence MUST be
treated as a connection error of type H3_FRAME_UNEXPECTED treated as a connection error of type H3_FRAME_UNEXPECTED
(Section 8). (Section 8).
A server MAY send one or more PUSH_PROMISE frames (see Section 7.2.5) A server MAY send one or more PUSH_PROMISE frames (see 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. These frames are not permitted in Section 4.4 for more details. These frames are not permitted in
pushed responses; a pushed response which includes PUSH_PROMISE pushed responses; a pushed response which includes PUSH_PROMISE
skipping to change at page 11, line 32 skipping to change at page 12, line 14
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 4.1 of [RFC7230] The "chunked" transfer encoding defined in Section 7.1 of [HTTP11]
MUST NOT be used. 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 informational responses (1xx; see Section 6.2 of [RFC7231]) more informational responses (1xx; see Section 9.2 of [SEMANTICS])
precede a final response to the same request. Non-final responses do precede a final response to the same request. Interim responses do
not contain a payload body or trailers. not contain a payload body or trailers.
If an endpoint receives an invalid sequence of frames on either a If an endpoint receives an invalid sequence of frames on either a
request or a push stream, it MUST respond with a connection error of request or a push stream, it MUST respond with a connection error of
type H3_FRAME_UNEXPECTED (Section 8). In particular, a DATA frame type H3_FRAME_UNEXPECTED (Section 8). In particular, a DATA frame
before any HEADERS frame, or a HEADERS or DATA frame after the before any HEADERS frame, or a HEADERS or DATA frame after the
trailing HEADERS frame is considered invalid. trailing HEADERS frame is considered invalid.
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
skipping to change at page 12, line 22 skipping to change at page 13, line 4
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
can always discard responses at their discretion for other reasons. can always discard responses at their discretion for other reasons.
If the server sends a partial or complete response but does not abort If the server sends a partial or complete response but does not abort
reading, clients SHOULD continue sending the body of the request and reading, clients SHOULD continue sending the body of the request and
close the stream normally. close the stream normally.
4.1.1. Header Formatting and Compression 4.1.1. Field Formatting and Compression
HTTP message headers carry information as a series of key-value HTTP messages carry metadata as a series of key-value pairs, called
pairs, called header fields. For a listing of registered HTTP header HTTP fields. For a listing of registered HTTP fields, see the
fields, see the "Message Header Field" registry maintained at "Hypertext Transfer Protocol (HTTP) Field Name Registry" maintained
https://www.iana.org/assignments/message-headers [4]. at https://www.iana.org/assignments/http-fields/ [4].
Just as in previous versions of HTTP, header field names are strings As in previous versions of HTTP, field names are strings containing a
of ASCII characters that are compared in a case-insensitive fashion. subset of ASCII characters that are compared in a case-insensitive
Properties of HTTP header field names and values are discussed in fashion. Properties of HTTP field names and values are discussed in
more detail in Section 3.2 of [RFC7230], though the wire rendering in more detail in Section 4.3 of [SEMANTICS]. As in HTTP/2, characters
HTTP/3 differs. As in HTTP/2, header field names MUST be converted in field names MUST be converted to lowercase prior to their
to lowercase prior to their encoding. A request or response encoding. A request or response containing uppercase characters in
containing uppercase header field names MUST be treated as malformed field names MUST be treated as malformed (Section 4.1.3).
(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 header fields; in this protocol, indicate connection-specific fields; in this protocol, connection-
connection-specific metadata is conveyed by other means. An endpoint specific metadata is conveyed by other means. An endpoint MUST NOT
MUST NOT generate an HTTP/3 message containing connection-specific generate an HTTP/3 field section containing connection-specific
header fields; any message containing connection-specific header fields; any message containing connection-specific fields MUST be
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; when it is, it MUST NOT contain any present in an HTTP/3 request header; when it is, it MUST NOT contain
value other than "trailers". any value other than "trailers".
This means that an intermediary transforming an HTTP/1.x message to This means that an intermediary transforming an HTTP/1.x message to
HTTP/3 will need to remove any header fields nominated by the HTTP/3 will need to remove any fields nominated by the Connection
Connection header field, along with the Connection header field field, along with the Connection field itself. Such intermediaries
itself. Such intermediaries SHOULD also remove other connection- SHOULD also remove other connection-specific fields, such as Keep-
specific header fields, such as Keep-Alive, Proxy-Connection, Alive, Proxy-Connection, Transfer-Encoding, and Upgrade, even if they
Transfer-Encoding, and Upgrade, even if they are not nominated by the are not nominated by the Connection field.
Connection header field.
4.1.1.1. Pseudo-Header Fields 4.1.1.1. Pseudo-Header Fields
As in HTTP/2, HTTP/3 uses special pseudo-header fields beginning with Like HTTP/2, HTTP/3 employs a series of pseudo-header fields where
the ':' character (ASCII 0x3a) to convey the target URI, the method the field name begins with the ':' character (ASCII 0x3a). These
of the request, and the status code for the response. pseudo-header fields convey the target URI, the method of the
request, and the status code for the response.
Pseudo-header fields are not HTTP header 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, except as negotiated via an extension; see Section 9. document, except as negotiated via an extension; 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
trailers. Endpoints MUST treat a request or response that contains trailers. 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 block before All pseudo-header fields MUST appear in the header field section
regular header fields. Any request or response that contains a before regular header fields. Any request or response that contains
pseudo-header field that appears in a header block after a regular a pseudo-header field that appears in a header field section after a
header field MUST be treated as malformed (Section 4.1.3). regular 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 ([RFC7231], Section 4) ":method": Contains the HTTP method (Section 7 of [SEMANTICS])
":scheme": Contains the scheme portion of the target URI ([RFC3986], ":scheme": Contains the scheme portion of the target URI
Section 3.1) (Section 3.1 of [RFC3986])
":scheme" is not restricted to "http" and "https" schemed URIs. A ":scheme" is not restricted to "http" and "https" schemed URIs. A
proxy or gateway can translate requests for non-HTTP schemes, proxy or gateway can translate requests for non-HTTP schemes,
enabling the use of HTTP to interact with non-HTTP services. enabling the use of HTTP to interact with non-HTTP services.
":authority": Contains the authority portion of the target URI ":authority": Contains the authority portion of the target URI
(Section 3.2 of [RFC3986]). The authority MUST NOT include the (Section 3.2 of [RFC3986]). The authority MUST NOT include the
deprecated "userinfo" subcomponent for "http" or "https" schemed deprecated "userinfo" subcomponent for "http" or "https" schemed
URIs. URIs.
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 5.3 of [RFC7230]). Clients origin or asterisk form (see Section 3.2 of [HTTP11]). 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 header field. An pseudo-header field instead of the Host field. An intermediary
intermediary that converts an HTTP/3 request to HTTP/1.1 MUST that converts an HTTP/3 request to HTTP/1.1 MUST create a Host
create a Host header field if one is not present in a request by field if one is not present in a request by copying the value of
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 [RFC3986]). by the "query" production (see Sections 3.3 and 3.4 of [RFC3986]).
A request in asterisk form includes the value '*' for the ":path" A 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 5.3.4 of [RFC7230]). with a value of '*' (see Section 3.2.4 of [HTTP11]).
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 (Section 4.2). An HTTP request that omits mandatory pseudo- request (Section 4.2).
header fields or contains invalid values for those fields is
malformed (Section 4.1.3). If the ":scheme" pseudo-header field identifies a scheme which has a
mandatory authority component (including "http" and "https"), the
request MUST contain either an ":authority" pseudo-header field or a
"Host" header field. If these fields are present, they MUST NOT be
empty. If both fields are present, they MUST contain the same value.
If the scheme does not have a mandatory authority component and none
is provided in the request target, the request MUST NOT contain the
":authority" pseudo-header and "Host" header fields.
An HTTP request that omits mandatory pseudo-header fields or contains
invalid values for those pseudo-header fields is malformed
(Section 4.1.3).
HTTP/3 does not define a way to carry the version identifier that is HTTP/3 does not define a way to carry the version identifier that is
included in the HTTP/1.1 request line. included in the HTTP/1.1 request line.
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 field (see Section 6 of [RFC7231]). carries the HTTP status code (see Section 9 of [SEMANTICS]). This
This pseudo-header field MUST be included in all responses; pseudo-header field MUST be included in all responses; otherwise, the
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. Header Compression 4.1.1.2. Field Compression
HTTP/3 uses QPACK header compression as described in [QPACK], a HTTP/3 uses QPACK field compression as described in [QPACK], a
variation of HPACK which allows the flexibility to avoid header- variation of HPACK which allows the flexibility to avoid compression-
compression-induced head-of-line blocking. See that document for induced head-of-line blocking. See that document for additional
additional details. details.
To allow for better compression efficiency, the cookie header field To allow for better compression efficiency, the "Cookie" field
[RFC6265] MAY be split into separate header fields, each with one or [RFC6265] MAY be split into separate field lines, each with one or
more cookie-pairs, before compression. If a decompressed header list more cookie-pairs, before compression. If a decompressed field
contains multiple cookie header fields, these MUST be concatenated section contains multiple cookie field lines, these MUST be
before being passed into a non-HTTP/2, non-HTTP/3 context, as concatenated into a single octet string using the two-octet delimiter
described in Section 8.1.2.5 of [HTTP2]. 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,
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 field list 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
code [RFC6585]. A client can discard responses that it cannot code ([RFC6585]). A client can discard responses that it cannot
process. The size of a header field list is calculated based on the process. The size of a field list is calculated based on the
uncompressed size of header fields, including the length of the name uncompressed size of fields, including the length of the name and
and value in bytes plus an overhead of 32 bytes for each header value in bytes plus an overhead of 32 bytes for each field.
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_HEADER_LIST_SIZE" parameter. An implementation which "SETTINGS_MAX_FIELD_SECTION_SIZE" parameter. An implementation which
has received this parameter SHOULD NOT send an HTTP message header has received this parameter SHOULD NOT send an HTTP message header
which exceeds the indicated size, as the peer will likely refuse to which exceeds the indicated size, as the peer will likely refuse to
process it. However, because this limit is applied at each hop, process it. However, because this limit is applied at each hop,
messages below this limit are not guaranteed to be accepted. messages below this limit are not guaranteed to be accepted.
4.1.2. Request Cancellation and Rejection 4.1.2. Request Cancellation and Rejection
Clients can cancel requests by resetting and aborting the request Clients can cancel requests by resetting and aborting the request
stream with an error code of H3_REQUEST_CANCELLED (Section 8.1). stream with an error code of H3_REQUEST_CANCELLED (Section 8.1).
When the client aborts reading a response, it indicates that this When the client aborts reading a response, it indicates that this
skipping to change at page 16, line 24 skipping to change at page 17, line 17
a stream is cancelled after receiving a partial response, the a stream is cancelled after receiving a partial response, the
response SHOULD NOT be used. Automatically retrying such requests is response SHOULD NOT be used. Automatically retrying such requests is
not possible, unless this is otherwise permitted (e.g., idempotent not possible, unless this is otherwise permitted (e.g., idempotent
actions like GET, PUT, or DELETE). actions like GET, PUT, or DELETE).
4.1.3. Malformed Requests and Responses 4.1.3. Malformed Requests and Responses
A malformed request or response is one that is an otherwise valid A malformed request or response is one that is an otherwise valid
sequence of frames but is invalid due to: sequence of frames but is invalid due to:
o the presence of prohibited header fields or pseudo-header fields, o the presence of prohibited fields or pseudo-header fields,
o the absence of mandatory pseudo-header fields, o the absence of mandatory pseudo-header fields,
o invalid values for pseudo-header fields, o invalid values for pseudo-header fields,
o pseudo-header fields after header fields, o pseudo-header fields after fields,
o an invalid sequence of HTTP messages, or o an invalid sequence of HTTP messages,
o the inclusion of uppercase header field names. o the inclusion of uppercase field names, or
o the inclusion of invalid characters in field names or values
A request or response that includes a payload body can include a A request or response that includes a payload body can include a
"content-length" header field. A request or response is also "content-length" header field. A request or response is also
malformed if the value of a content-length header field does not malformed if the value of a content-length header field does not
equal the sum of the DATA frame payload lengths that form the body. equal the sum of the DATA frame payload lengths that form the body.
A response that is defined to have no payload, as described in A response that is defined to have no payload, as described in
Section 3.3.2 of [RFC7230] can have a non-zero content-length header Section 6.3.3 of [SEMANTICS] can have a non-zero content-length
field, even though no content is included in DATA frames. field, 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_GENERAL_PROTOCOL_ERROR. H3_GENERAL_PROTOCOL_ERROR.
For malformed requests, a server MAY send an HTTP response prior to For malformed requests, a server MAY send an HTTP response prior to
closing or resetting the stream. Clients MUST NOT accept a malformed closing or resetting the stream. Clients MUST NOT accept a malformed
response. Note that these requirements are intended to protect response. Note that these requirements are intended to protect
against several types of common attacks against HTTP; they are against several types of common attacks against HTTP; they are
deliberately strict because being permissive can expose deliberately strict because being permissive can expose
implementations to these vulnerabilities. implementations to these vulnerabilities.
4.2. The CONNECT Method 4.2. The CONNECT Method
The pseudo-method CONNECT (Section 4.3.6 of [RFC7231]) is primarily The CONNECT method requests that the recipient establish a tunnel to
used with HTTP proxies to establish a TLS session with an origin the destination origin server identified by the request-target
server for the purposes of interacting with "https" resources. In (Section 3.2 of [HTTP11]). It is primarily used with HTTP proxies to
HTTP/1.x, CONNECT is used to convert an entire HTTP connection into a establish a TLS session with an origin server for the purposes of
tunnel to a remote host. In HTTP/2, the CONNECT method is used to interacting with "https" resources.
establish a tunnel over a single HTTP/2 stream to a remote host for
similar purposes.
A CONNECT request in HTTP/3 functions in the same manner as in In HTTP/1.x, CONNECT is used to convert an entire HTTP connection
HTTP/2. The request MUST be formatted as described in Section 8.3 of into a tunnel to a remote host. In HTTP/2 and HTTP/3, the CONNECT
[HTTP2]. A CONNECT request that does not conform to these method is used to establish a tunnel over a single stream.
restrictions is malformed (see Section 4.1.3). The request stream
MUST NOT be closed at the end of the request. A CONNECT request MUST be constructed as follows:
o The ":method" pseudo-header field is set to "CONNECT"
o The ":scheme" and ":path" pseudo-header fields are omitted
o The ":authority" pseudo-header field contains the host and port to
connect to (equivalent to the authority-form of the request-target
of CONNECT requests (see Section 5.3 of [HTTP11]))
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
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 4.3.6 of [RFC7231]. the client, as defined in Section 9.3 of [SEMANTICS].
All DATA frames on the stream correspond to data sent or received on All DATA frames on the stream correspond to data sent or received on
the TCP connection. Any DATA frame sent by the client is transmitted the TCP connection. Any DATA frame sent by the client is transmitted
by the proxy to the TCP server; data received from the TCP server is by the proxy to the TCP server; data received from the TCP server is
packaged into DATA frames by the proxy. Note that the size and packaged into DATA frames by the proxy. Note that the size and
number of TCP segments is not guaranteed to map predictably to the number of TCP segments is not guaranteed to map predictably to the
size and number of HTTP DATA or QUIC STREAM frames. size and number of HTTP DATA or QUIC STREAM frames.
Once the CONNECT method has completed, only DATA frames are permitted Once the CONNECT method has completed, only DATA frames are permitted
to be sent on the stream. Extension frames MAY be used if to be sent on the stream. Extension frames MAY be used if
skipping to change at page 18, line 15 skipping to change at page 19, line 21
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 (Section 8.1). Correspondingly, if a error of type H3_CONNECT_ERROR (Section 8.1). 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.
4.3. HTTP Upgrade 4.3. HTTP Upgrade
HTTP/3 does not support the HTTP Upgrade mechanism (Section 6.7 of HTTP/3 does not support the HTTP Upgrade mechanism (Section 9.9 of
[RFC7230]) or 101 (Switching Protocols) informational status code [HTTP11]) or 101 (Switching Protocols) informational status code
(Section 6.2.2 of [RFC7231]). (Section 9.2.2 of [SEMANTICS]).
4.4. Server Push 4.4. Server Push
Server push is an interaction mode introduced in HTTP/2 [HTTP2] which Server push is an interaction mode which permits a server to push a
permits a server to push a request-response exchange to a client in request-response exchange to a client in anticipation of the client
anticipation of the client making the indicated request. This trades making the indicated request. This trades off network usage against
off network usage against a potential latency gain. HTTP/3 server a potential latency gain. HTTP/3 server push is similar to what is
push is similar to what is described in HTTP/2 [HTTP2], but uses described in HTTP/2 [HTTP2], but uses different mechanisms.
different mechanisms.
Each server push is identified by a unique Push ID. This Push ID is Each server push is identified by a unique Push ID. This Push ID is
used in one or more PUSH_PROMISE frames (see Section 7.2.5) that used in one or more PUSH_PROMISE frames (see Section 7.2.5) that
carry the request headers, then included with the push stream which carry the request fields, then included with the push stream which
ultimately fulfills those promises. When the same Push ID is ultimately fulfills those promises. When the same Push ID is
promised on multiple request streams, the decompressed request header promised on multiple request streams, the decompressed request field
sets MUST contain the same fields in the same order, and both the sections MUST contain the same fields in the same order, and both the
name and the value in each field MUST be exact matches. name and the value in each field MUST be exact matches.
Server push is only enabled on a connection when a client sends a Server push is only enabled on a connection when a client sends a
MAX_PUSH_ID frame (see Section 7.2.7). A server cannot use server MAX_PUSH_ID frame (see Section 7.2.7). A server cannot use server
push until it receives a MAX_PUSH_ID frame. A client sends push until it receives a MAX_PUSH_ID frame. A client sends
additional MAX_PUSH_ID frames to control the number of pushes that a additional MAX_PUSH_ID frames to control the number of pushes that a
server can promise. A server SHOULD use Push IDs sequentially, server can promise. A server SHOULD use Push IDs sequentially,
starting at 0. A client MUST treat receipt of a push stream with a starting at 0. A client MUST treat receipt of a push stream with a
Push ID that is greater than the maximum Push ID as a connection Push ID that is greater than the maximum Push ID as a connection
error of type H3_ID_ERROR. error of type H3_ID_ERROR.
The header of the request message is carried by a PUSH_PROMISE frame The header section of the request message is carried by a
(see Section 7.2.5) on the request stream which generated the push. PUSH_PROMISE frame (see Section 7.2.5) on the request stream which
Promised requests MUST conform to the requirements in Section 8.2 of generated the push. This allows the server push to be associated
[HTTP2]. with a client request.
Not all requests can be pushed. A server MAY push requests which
have the following properties:
o cacheable (see Section 7.2.3 of [SEMANTICS])
o safe (see Section 7.2.1 of [SEMANTICS])
o does not include a request body or trailer section
Clients SHOULD send a CANCEL_PUSH frame upon receipt of a
PUSH_PROMISE frame carrying a request which is not cacheable, is not
known to be safe, or that indicates the presence of a request body.
If the pushed response arrives on a push stream, this MAY be treated
as a stream error of type H3_STREAM_CREATION_ERROR.
The server MUST include a value in the ":authority" pseudo-header
field for which the server is authoritative (see Section 3.4). A
client SHOULD send a CANCEL_PUSH frame upon receipt of a PUSH_PROMISE
frame carrying a request for which it does not consider the server
authoritative. If the pushed response arrives on a push stream, this
MAY be treated as a stream error of type H3_STREAM_CREATION_ERROR.
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
associated with additional client requests using a PUSH_PROMISE frame associated with additional client requests using a PUSH_PROMISE frame
with the same Push ID on multiple request streams. These with the same Push ID on multiple request streams. These
associations do not affect the operation of the protocol, but MAY be associations do not affect the operation of the protocol, but MAY be
considered by user agents when deciding how to use pushed resources. considered by user agents when deciding how to use pushed resources.
Ordering of a PUSH_PROMISE in relation to certain parts of the Ordering of a PUSH_PROMISE in relation to certain parts of the
skipping to change at page 19, line 24 skipping to change at page 21, line 4
When a server later fulfills a promise, the server push response is When a server later fulfills a promise, the server push response is
conveyed on a push stream (see Section 6.2.2). The push stream conveyed on a push stream (see Section 6.2.2). The push stream
identifies the Push ID of the promise that it fulfills, then contains identifies the Push ID of the promise that it fulfills, then contains
a response to the promised request using the same format described a response to the promised request using the same format described
for responses in Section 4.1. for responses in Section 4.1.
Due to reordering, push stream data can arrive before the Due to reordering, push stream data can arrive before the
corresponding PUSH_PROMISE frame. When a client receives a new push corresponding PUSH_PROMISE frame. When a client receives a new push
stream with an as-yet-unknown Push ID, both the associated client stream with an as-yet-unknown Push ID, both the associated client
request and the pushed request headers are unknown. The client can request and the pushed request header fields are unknown. The client
buffer the stream data in expectation of the matching PUSH_PROMISE. can buffer the stream data in expectation of the matching
The client can use stream flow control (see section 4.1 of PUSH_PROMISE. The client can use stream flow control (see section
[QUIC-TRANSPORT]) to limit the amount of data a server may commit to 4.1 of [QUIC-TRANSPORT]) to limit the amount of data a server may
the pushed stream. commit to the pushed stream.
If a promised server push is not needed by the client, the client If a promised server push is not needed by the client, the client
SHOULD send a CANCEL_PUSH frame. If the push stream is already open SHOULD send a CANCEL_PUSH frame. If the push stream is already open
or opens after sending the CANCEL_PUSH frame, the client can abort or opens after sending the CANCEL_PUSH frame, the client can abort
reading the stream with an error code of H3_REQUEST_CANCELLED. This reading the stream with an error code of H3_REQUEST_CANCELLED. This
asks the server not to transfer additional data and indicates that it asks the server not to transfer additional data and indicates that it
will be discarded upon receipt. will be discarded upon receipt.
Pushed responses that are cacheable (see Section 3 of [CACHING]) can
be stored by the client, if it implements an HTTP cache. Pushed
responses are considered successfully validated on the origin server
(e.g., if the "no-cache" cache response directive is present
(Section 5.2.2.3 of [CACHING])) at the time the pushed response is
received.
Pushed responses that are not cacheable MUST NOT be stored by any
HTTP cache. They MAY be made available to the application
separately.
5. Connection Closure 5. Connection Closure
Once established, an HTTP/3 connection can be used for many requests Once established, an HTTP/3 connection can be used for many requests
and responses over time until the connection is closed. Connection and responses over time until the connection is closed. Connection
closure can happen in any of several different ways. closure can happen in any of several different ways.
5.1. Idle Connections 5.1. Idle Connections
Each QUIC endpoint declares an idle timeout during the handshake. If Each QUIC endpoint declares an idle timeout during the handshake. If
the connection remains idle (no packets received) for longer than the connection remains idle (no packets received) for longer than
skipping to change at page 20, line 18 skipping to change at page 22, line 10
If the client is not expecting a response from the server, allowing If the client is not expecting a response from the server, allowing
an idle connection to time out is preferred over expending effort an idle connection to time out is preferred over expending effort
maintaining a connection that might not be needed. A gateway MAY maintaining a connection that might not be needed. A gateway MAY
maintain connections in anticipation of need rather than incur the maintain connections in anticipation of need rather than incur the
latency cost of connection establishment to servers. Servers SHOULD latency cost of connection establishment to servers. Servers SHOULD
NOT actively keep connections open. NOT actively keep connections open.
5.2. Connection Shutdown 5.2. Connection Shutdown
Even when a connection is not idle, either endpoint can decide to Even when a connection is not idle, either endpoint can decide to
stop using the connection and let the connection close gracefully. stop using the connection and initiate a graceful connection close.
Since clients drive request generation, clients perform a connection Endpoints initiate the graceful shutdown of a connection by sending a
shutdown by not sending additional requests on the connection; GOAWAY frame (Section 7.2.6). The GOAWAY frame contains an
responses and pushed responses associated to previous requests will identifier that indicates to the receiver the range of requests or
continue to completion. Servers perform the same function by pushes that were or might be processed in this connection. The
communicating with clients. server sends a client-initiated bidirectional Stream ID; the client
sends a Push ID. Requests or pushes with the indicated identifier or
greater are rejected by the sender of the GOAWAY. This identifier
MAY be zero if no requests or pushes were processed.
Servers initiate the shutdown of a connection by sending a GOAWAY The information in the GOAWAY frame enables a client and server to
frame (Section 7.2.6). The GOAWAY frame indicates that client- agree on which requests or pushes were accepted prior to the
initiated requests on lower stream IDs were or might be processed in connection shutdown. Upon sending a GOAWAY frame, the endpoint
this connection, while requests on the indicated stream ID and SHOULD explicitly cancel (see Section 4.1.2 and Section 7.2.3) any
greater were rejected. This enables client and server to agree on requests or pushes that have identifiers greater than or equal to
which requests were accepted prior to the connection shutdown. This that indicated, in order to clean up transport state for the affected
identifier MAY be zero if no requests were processed. Servers SHOULD streams. The endpoint SHOULD continue to do so as more requests or
NOT permit additional QUIC streams after sending a GOAWAY frame. pushes arrive.
Clients MUST NOT send new requests on the connection after receiving Endpoints MUST NOT initiate new requests or promise new pushes on the
GOAWAY; a new connection MAY be established to send additional connection after receipt of a GOAWAY frame from the peer. Clients
requests. MAY establish a new connection to send additional requests.
Some requests might already be in transit. If the client has already Some requests or pushes might already be in transit:
sent requests on streams with a Stream ID greater than or equal to
that indicated in the GOAWAY frame, those requests will not be
processed and MAY be retried by the client on a different connection.
The client MAY cancel these requests. It is RECOMMENDED that the
server explicitly reject such requests (see Section 4.1.2) in order
to clean up transport state for the affected streams.
Requests on Stream IDs less than the Stream ID in the GOAWAY frame o Upon receipt of a GOAWAY frame, if the client has already sent
might have been processed; their status cannot be known until a requests with a Stream ID greater than or equal to the identifier
response is received, the stream is reset individually, or the received in a GOAWAY frame, those requests will not be processed.
connection terminates. Servers MAY reject individual requests on Clients can safely retry unprocessed requests on a different
streams below the indicated ID if these requests were not processed. connection.
Requests on Stream IDs less than the Stream ID in a GOAWAY frame
from the server might have been processed; their status cannot be
known until a response is received, the stream is reset
individually, another GOAWAY is received, or the connection
terminates.
Servers MAY reject individual requests on streams below the
indicated ID if these requests were not processed.
o If a server receives a GOAWAY frame after having promised pushes
with a Push ID greater than or equal to the identifier received in
a 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
is known in advance, even if the advance notice is small, so that the is known in advance, even if the advance notice is small, so that the
remote peer can know whether a request has been partially processed remote peer can know whether a request has been partially processed
or not. For example, if an HTTP client sends a POST at the same time or not. For example, if an HTTP client sends a POST at the same time
that a server closes a QUIC connection, the client cannot know if the that a server closes a QUIC connection, the client cannot know if the
server started to process that POST request if the server does not server started to process that POST request if the server does not
send a GOAWAY frame to indicate what streams it might have acted on. send a GOAWAY frame to indicate what streams it might have acted on.
A client that is unable to retry requests loses all requests that are A client that is unable to retry requests loses all requests that are
in flight when the server closes the connection. A server MAY send in flight when the server closes the connection. An endpoint MAY
multiple GOAWAY frames indicating different stream IDs, but MUST NOT send multiple GOAWAY frames indicating different identifiers, but
increase the value they send in the last Stream ID, since clients MUST NOT increase the identifier value they send, since clients might
might already have retried unprocessed requests on another already have retried unprocessed requests on another connection.
connection.
A server that is attempting to gracefully shut down a connection can An endpoint that is attempting to gracefully shut down a connection
send an initial GOAWAY frame with the last Stream ID set to the can send a GOAWAY frame with a value set to the maximum possible
maximum possible value for a client-initiated, bidirectional stream value (2^62-4 for servers, 2^62-1 for clients). This ensures that
(i.e. 2^62-4 in case of QUIC version 1). This GOAWAY frame signals the peer stops creating new requests or pushes. After allowing time
to the client that shutdown is imminent and that initiating further for any in-flight requests or pushes to arrive, the endpoint can send
requests is prohibited. After allowing time for any in-flight another GOAWAY frame indicating which requests or pushes it might
requests to reach the server, the server can send another GOAWAY accept before the end of the connection. This ensures that a
frame indicating which requests it will accept before the end of the connection can be cleanly shut down without losing requests.
connection. This ensures that a connection can be cleanly shut down
without causing requests to fail.
Once all accepted requests have been processed, the server can permit A client has more flexibility in the value it chooses for the Push ID
the connection to become idle, or MAY initiate an immediate closure in a GOAWAY that it sends. A value of 2^62 - 1 indicates that the
of the connection. An endpoint that completes a graceful shutdown server can continue fulfilling pushes which have already been
SHOULD use the H3_NO_ERROR code when closing the connection. promised, and the client can continue granting push credit as needed
(see Section 7.2.7). A smaller value indicates the client will
reject pushes with Push IDs greater than or equal to this value.
Like the server, the client MAY send subsequent GOAWAY frames so long
as the specified Push ID is strictly smaller than all previously sent
values.
Even when a GOAWAY indicates that a given request or push will not be
processed or accepted upon receipt, the underlying transport
resources still exist. The endpoint that initiated these requests
can cancel them to clean up transport state.
Once all accepted requests and pushes have been processed, the
endpoint can permit the connection to become idle, or MAY initiate an
immediate closure of the connection. An endpoint that completes a
graceful shutdown SHOULD use the HTTP_NO_ERROR code when closing the
connection.
If a client has consumed all available bidirectional stream IDs with If a client has consumed all available bidirectional stream IDs with
requests, the server need not send a GOAWAY frame, since the client requests, the server need not send a GOAWAY frame, since the client
is unable to make further requests. is unable to make further requests.
5.3. Immediate Application Closure 5.3. Immediate Application Closure
An HTTP/3 implementation can immediately close the QUIC connection at An HTTP/3 implementation can immediately close the QUIC connection at
any time. This results in sending a QUIC CONNECTION_CLOSE frame to any time. This results in sending a QUIC CONNECTION_CLOSE frame to
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 which can be used when closing a connection in HTTP/3. codes which can be used when closing a connection in HTTP/3.
Before closing the connection, a GOAWAY MAY be sent to allow the Before closing the connection, a GOAWAY frame MAY be sent to allow
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.
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 which interrupts connectivity. change in network topology which interrupts connectivity.
skipping to change at page 22, line 32 skipping to change at page 24, line 50
layer buffers and orders received QUIC STREAM frames, exposing the layer buffers and orders received QUIC STREAM frames, exposing the
data contained within as a reliable byte stream to the application. data contained within as a reliable byte stream to the application.
Although QUIC permits out-of-order delivery within a stream, HTTP/3 Although QUIC permits out-of-order delivery within a stream, HTTP/3
does not make use of this feature. 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 headers 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 connection context. maps to a particular HTTP transaction or connection context.
6.1. Bidirectional Streams 6.1. Bidirectional Streams
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. This means that the client's be readily correlated with the request. This means that the client's
first request occurs on QUIC stream 0, with subsequent requests on first request occurs on QUIC stream 0, with subsequent requests on
skipping to change at page 25, line 6 skipping to change at page 27, line 26
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 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- the Push ID of the promise that it fulfills, encoded as a variable-
length integer. The remaining data on this stream consists of HTTP/3 length integer. The remaining data on this stream consists of HTTP/3
frames, as defined in Section 7.2, and fulfills a promised server frames, as defined in Section 7.2, and fulfills a promised server
push by zero or more non-final HTTP responses followed by a single push by zero or more interim HTTP responses followed by a single
final HTTP response, as defined in Section 4.1. Server push and Push final HTTP response, as defined in Section 4.1. Server push and Push
IDs are described in Section 4.4. IDs are described in Section 4.4.
Only servers can push; if a server receives a client-initiated push Only servers can push; if a server receives a client-initiated push
stream, this MUST be treated as a connection error of type stream, this MUST be treated as a connection error of type
H3_STREAM_CREATION_ERROR. H3_STREAM_CREATION_ERROR.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 28, line 15 skipping to change at page 31, line 15
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload (*) ... | Payload (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: DATA Frame Payload Figure 4: DATA Frame Payload
7.2.2. HEADERS 7.2.2. HEADERS
The HEADERS frame (type=0x1) is used to carry a header block, The HEADERS frame (type=0x1) is used to carry an HTTP field section,
compressed using QPACK. See [QPACK] for more details. encoded using QPACK. See [QPACK] for more details.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Header Block (*) ... | Encoded Field Section (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: HEADERS Frame Payload Figure 5: HEADERS Frame Payload
HEADERS frames can only be sent on request / push streams. If a HEADERS frames can only be sent on request / push streams. If a
HEADERS frame is received on a control stream, the recipient MUST HEADERS frame is received on a control stream, the recipient MUST
respond with a connection error (Section 8) of type respond with a connection error (Section 8) of type
H3_FRAME_UNEXPECTED. H3_FRAME_UNEXPECTED.
7.2.3. CANCEL_PUSH 7.2.3. CANCEL_PUSH
skipping to change at page 30, line 17 skipping to change at page 33, line 17
SETTINGS parameters are not negotiated; they describe characteristics SETTINGS parameters are not negotiated; they describe characteristics
of the sending peer, which can be used by the receiving peer. of the sending peer, which can be used by the receiving peer.
However, a negotiation can be implied by the use of SETTINGS - each However, a negotiation can be implied by the use of SETTINGS - each
peer uses SETTINGS to advertise a set of supported values. The peer uses SETTINGS to advertise a set of supported values. The
definition of the setting would describe how each peer combines the definition of the setting would describe how each peer combines the
two sets to conclude which choice will be used. SETTINGS does not two sets to conclude which choice will be used. SETTINGS does not
provide a mechanism to identify when the choice takes effect. provide a mechanism to identify when the choice takes effect.
Different values for the same parameter can be advertised by each Different values for the same parameter can be advertised by each
peer. For example, a client might be willing to consume a very large peer. For example, a client might be willing to consume a very large
response header, while servers are more cautious about request size. response field section, while servers are more cautious about request
size.
The same setting identifier MUST NOT occur more than once in the The same setting identifier MUST NOT occur more than once in the
SETTINGS frame. A receiver MAY treat the presence of duplicate SETTINGS frame. A receiver MAY treat the presence of duplicate
setting identifiers as a connection error of type H3_SETTINGS_ERROR. setting identifiers as a connection error of type H3_SETTINGS_ERROR.
The payload of a SETTINGS frame consists of zero or more parameters. The payload of a SETTINGS frame consists of zero or more parameters.
Each parameter consists of a setting identifier and a value, both Each parameter consists of a setting identifier and a value, both
encoded as QUIC variable-length integers. encoded as QUIC variable-length integers.
0 1 2 3 0 1 2 3
skipping to change at page 30, line 44 skipping to change at page 33, line 45
Figure 7: SETTINGS Parameter Format Figure 7: SETTINGS Parameter Format
An implementation MUST ignore the contents for any SETTINGS An implementation MUST ignore the contents for any SETTINGS
identifier it does not understand. identifier it 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_HEADER_LIST_SIZE (0x6): The default value is unlimited. SETTINGS_MAX_FIELD_SECTION_SIZE (0x6): The default value is
See Section 4.1.1 for usage. unlimited. See Section 4.1.1 for usage.
Setting identifiers of the format "0x1f * N + 0x21" for integer Setting identifiers of the format "0x1f * N + 0x21" for integer
values of N are reserved to exercise the requirement that unknown values of N are reserved to exercise the requirement that unknown
identifiers be ignored. Such settings have no defined meaning. identifiers be ignored. Such settings have no defined meaning.
Endpoints SHOULD include at least one such setting in their SETTINGS Endpoints SHOULD include at least one such setting in their SETTINGS
frame. Endpoints MUST NOT consider such settings to have any meaning frame. Endpoints MUST NOT consider such settings to have any meaning
upon receipt. 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.
skipping to change at page 32, line 27 skipping to change at page 35, line 27
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 set from server to client on a request stream, as in HTTP/2. header field section from server to client on a request stream, as in
HTTP/2.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Push ID (i) ... | Push ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Header Block (*) ... | Encoded Field Section (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: PUSH_PROMISE Frame Payload Figure 8: PUSH_PROMISE Frame Payload
The payload consists of: The payload consists of:
Push ID: A variable-length integer that identifies the server push Push ID: A variable-length integer that identifies the server push
operation. A Push ID is used in push stream headers operation. A Push ID is used in push stream headers
(Section 4.4), CANCEL_PUSH frames (Section 7.2.3). (Section 4.4), CANCEL_PUSH frames (Section 7.2.3).
Header Block: QPACK-compressed request header fields for the Encoded Field Section: QPACK-encoded request header fields for the
promised response. See [QPACK] for more details. promised response. See [QPACK] for more details.
A server MUST NOT use a Push ID that is larger than the client has A server MUST NOT use a Push ID that is larger than the client has
provided in a MAX_PUSH_ID frame (Section 7.2.7). A client MUST treat provided in a MAX_PUSH_ID frame (Section 7.2.7). A client MUST treat
receipt of a PUSH_PROMISE frame that contains a larger Push ID than receipt of a PUSH_PROMISE frame that contains a larger Push ID than
the client has advertised as a connection error of H3_ID_ERROR. the client has advertised as a connection error of H3_ID_ERROR.
A server MAY use the same Push ID in multiple PUSH_PROMISE frames. A server MAY use the same Push ID in multiple PUSH_PROMISE frames.
If so, the decompressed request header sets MUST contain the same If so, the decompressed request header sets MUST contain the same
fields in the same order, and both the name and and value in each fields in the same order, and both the name and the value in each
field MUST be exact matches. Clients SHOULD compare the request field MUST be exact matches. Clients SHOULD compare the request
header sets for resources promised multiple times. If a client header sections for resources promised multiple times. If a client
receives a Push ID that has already been promised and detects a receives a Push ID that has already been promised and detects a
mismatch, it MUST respond with a connection error of type mismatch, it MUST respond with a connection error of type
H3_GENERAL_PROTOCOL_ERROR. If the decompressed header sets match H3_GENERAL_PROTOCOL_ERROR. If the decompressed field sections match
exactly, the client SHOULD associate the pushed content with each exactly, the client SHOULD associate the pushed content with each
stream on which a PUSH_PROMISE was received. stream on which a PUSH_PROMISE was received.
Allowing duplicate references to the same Push ID is primarily to Allowing duplicate references to the same Push ID is primarily to
reduce duplication caused by concurrent requests. A server SHOULD reduce duplication caused by concurrent requests. A server SHOULD
avoid reusing a Push ID over a long period. Clients are likely to avoid reusing a Push ID over a long period. Clients are likely to
consume server push responses and not retain them for reuse over consume server push responses and not retain them for reuse over
time. Clients that see a PUSH_PROMISE that uses a Push ID that they time. Clients that see a PUSH_PROMISE that uses a Push ID that they
have already consumed and discarded are forced to ignore the have already consumed and discarded are forced to ignore the
PUSH_PROMISE. PUSH_PROMISE.
skipping to change at page 33, line 38 skipping to change at page 36, line 40
A client MUST NOT send a PUSH_PROMISE frame. A server MUST treat the A client MUST NOT send a PUSH_PROMISE frame. A server MUST treat the
receipt of a PUSH_PROMISE frame as a connection error of type receipt of a PUSH_PROMISE frame as a connection error of type
H3_FRAME_UNEXPECTED. H3_FRAME_UNEXPECTED.
See Section 4.4 for a description of the overall server push See Section 4.4 for a description of the overall server push
mechanism. mechanism.
7.2.6. GOAWAY 7.2.6. GOAWAY
The GOAWAY frame (type=0x7) is used to initiate graceful shutdown of The GOAWAY frame (type=0x7) is used to initiate graceful shutdown of
a connection by a server. GOAWAY allows a server to stop accepting a connection by either endpoint. GOAWAY allows an endpoint to stop
new requests while still finishing processing of previously received accepting new requests or pushes while still finishing processing of
requests. This enables administrative actions, like server previously received requests and pushes. This enables administrative
maintenance. GOAWAY by itself does not close a connection. actions, like server maintenance. GOAWAY by itself does not close a
connection.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (i) ... | Stream ID/Push ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: GOAWAY Frame Payload Figure 9: GOAWAY Frame Payload
The GOAWAY frame is always sent on the control stream. It carries a The GOAWAY frame is always sent on the control stream. In the server
QUIC Stream ID for a client-initiated bidirectional stream encoded as to client direction, it carries a QUIC Stream ID for a client-
a variable-length integer. A client MUST treat receipt of a GOAWAY initiated bidirectional stream encoded as a variable-length integer.
frame containing a Stream ID of any other type as a connection error A client MUST treat receipt of a GOAWAY frame containing a Stream ID
of type H3_ID_ERROR. of any other type as a connection error of type H3_ID_ERROR.
Clients do not need to send GOAWAY to initiate a graceful shutdown; In the client to server direction, the GOAWAY frame carries a Push ID
they simply stop making new requests. A server MUST treat receipt of encoded as a variable-length integer.
a GOAWAY frame on any stream as a connection error (Section 8) of
type H3_FRAME_UNEXPECTED.
The GOAWAY frame applies to the connection, not a specific stream. A The GOAWAY frame applies to the connection, not a specific stream. A
client MUST treat a GOAWAY frame on a stream other than the control client MUST treat a GOAWAY frame on a stream other than the control
stream as a connection error (Section 8) of type H3_FRAME_UNEXPECTED. stream as a connection error (Section 8) of type H3_FRAME_UNEXPECTED.
See Section 5.2 for more information on the use of the GOAWAY frame. See Section 5.2 for more information on the use of the GOAWAY frame.
7.2.7. MAX_PUSH_ID 7.2.7. MAX_PUSH_ID
The MAX_PUSH_ID frame (type=0xD) is used by clients to control the The MAX_PUSH_ID frame (type=0xD) is used by clients to control the
skipping to change at page 37, line 20 skipping to change at page 40, line 32
9. Extensions to HTTP/3 9. Extensions to HTTP/3
HTTP/3 permits extension of the protocol. Within the limitations HTTP/3 permits extension of the protocol. Within the limitations
described in this section, protocol extensions can be used to provide described in this section, protocol extensions can be used to provide
additional services or alter any aspect of the protocol. Extensions additional services or alter any aspect of the protocol. Extensions
are effective only within the scope of a single HTTP/3 connection. are effective only within the scope of a single HTTP/3 connection.
This applies to the protocol elements defined in this document. This This applies to the protocol elements defined in this document. This
does not affect the existing options for extending HTTP, such as does not affect the existing options for extending HTTP, such as
defining new methods, status codes, or header fields. defining new methods, status codes, or fields.
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
skipping to change at page 38, line 10 skipping to change at page 41, line 21
use of an extension but notes that a setting (Section 7.2.4.1) could use of an extension but notes that a setting (Section 7.2.4.1) could
be used for that purpose. If both peers set a value that indicates be used for that purpose. If both peers set a value that indicates
willingness to use the extension, then the extension can be used. If willingness to use the extension, then the extension can be used. If
a setting is used for extension negotiation, the default value MUST a setting is used for extension negotiation, the default value MUST
be defined in such a fashion that the extension is disabled if the be defined in such a fashion that the extension is disabled if the
setting is omitted. setting is omitted.
10. Security Considerations 10. Security Considerations
The security considerations of HTTP/3 should be comparable to those The security considerations of HTTP/3 should be comparable to those
of HTTP/2 with TLS; the considerations from Section 10 of [HTTP2] of HTTP/2 with TLS. However, many of the considerations from
apply in addition to those listed here. Section 10 of [HTTP2] apply to [QUIC-TRANSPORT] and are discussed in
that document.
When HTTP Alternative Services is used for discovery for HTTP/3 10.1. Server Authority
endpoints, the security considerations of [ALTSVC] also apply.
10.1. Traffic Analysis HTTP/3 relies on the HTTP definition of authority. The security
considerations of establishing authority are discussed in
Section 11.1 of [SEMANTICS].
10.2. Cross-Protocol Attacks
The use of ALPN in the TLS and QUIC handshakes establishes the target
application protocol before application-layer bytes are processed.
Because all QUIC packets are encrypted, it is difficult for an
attacker to control the plaintext bytes of an HTTP/3 connection which
could be used in a cross-protocol attack on a plaintext protocol.
10.3. Intermediary Encapsulation Attacks
The HTTP/3 field encoding allows the expression of names that are not
valid field names in the syntax used by HTTP (Section 4.3 of
[SEMANTICS]). Requests or responses containing invalid field names
MUST be treated as malformed (Section 4.1.3). An intermediary
therefore cannot translate an HTTP/3 request or response containing
an invalid field name into an HTTP/1.1 message.
Similarly, HTTP/3 allows field values that are not valid. While most
of the values that can be encoded will not alter field parsing,
carriage return (CR, ASCII 0xd), line feed (LF, ASCII 0xa), and the
zero character (NUL, ASCII 0x0) might be exploited by an attacker if
they are translated verbatim. Any request or response that contains
a character not permitted in a field value MUST be treated as
malformed (Section 4.1.3). Valid characters are defined by the
"field-content" ABNF rule in Section 4.4 of [SEMANTICS].
10.4. Cacheability of Pushed Responses
Pushed responses do not have an explicit request from the client; the
request is provided by the server in the PUSH_PROMISE frame.
Caching responses that are pushed is possible based on the guidance
provided by the origin server in the Cache-Control header field.
However, this can cause issues if a single server hosts more than one
tenant. For example, a server might offer multiple users each a
small portion of its URI space.
Where multiple tenants share space on the same server, that server
MUST ensure that tenants are not able to push representations of
resources that they do not have authority over. Failure to enforce
this would allow a tenant to provide a representation that would be
served out of cache, overriding the actual representation that the
authoritative tenant provides.
Pushed responses for which an origin server is not authoritative (see
Section 3.4) MUST NOT be used or cached.
10.5. Denial-of-Service Considerations
An HTTP/3 connection can demand a greater commitment of resources to
operate than an HTTP/1.1 or HTTP/2 connection. The use of field
compression and flow control depend on a commitment of resources for
storing a greater amount of state. Settings for these features
ensure that memory commitments for these features are strictly
bounded.
The number of PUSH_PROMISE frames is constrained in a similar
fashion. A client that accepts server push SHOULD limit the number
of Push IDs it issues at a time.
Processing capacity cannot be guarded as effectively as state
capacity.
The ability to send undefined protocol elements which the peer is
required to ignore can be abused to cause a peer to expend additional
processing time. This might be done by setting multiple undefined
SETTINGS parameters, unknown frame types, or unknown stream types.
Note, however, that some uses are entirely legitimate, such as
optional-to-understand extensions and padding to increase resistance
to traffic analysis.
Compression of field sections also offers some opportunities to waste
processing resources; see Section 7 of [QPACK] for more details on
potential abuses.
All these features - i.e., server push, unknown protocol elements,
field compression - have legitimate uses. These features become a
burden only when they are used unnecessarily or to excess.
An endpoint that doesn't monitor this behavior exposes itself to a
risk of denial-of-service attack. Implementations SHOULD track the
use of these features and set limits on their use. An endpoint MAY
treat activity that is suspicious as a connection error (Section 8)
of type H3_EXCESSIVE_LOAD, but false positives will result in
disrupting valid connections and requests.
10.5.1. Limits on Field Section Size
A large field section (Section 4.1) can cause an implementation to
commit a large amount of state. Header fields that are critical for
routing can appear toward the end of a header field section, which
prevents streaming of the header field section to its ultimate
destination. This ordering and other reasons, such as ensuring cache
correctness, mean that an endpoint likely needs to buffer the entire
header field section. Since there is no hard limit to the size of a
field section, some endpoints could be forced to commit a large
amount of available memory for header fields.
An endpoint can use the SETTINGS_MAX_HEADER_LIST_SIZE
(Section 7.2.4.1) setting to advise peers of limits that might apply
on the size of field sections. This setting is only advisory, so
endpoints MAY choose to send field sections that exceed this limit
and risk having the request or response being treated as malformed.
This setting is specific to a connection, so any request or response
could encounter a hop with a lower, unknown limit. An intermediary
can attempt to avoid this problem by passing on values 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
handle can send an HTTP 431 (Request Header Fields Too Large) status
code [RFC6585]. A client can discard responses that it cannot
process.
10.5.2. CONNECT Issues
The CONNECT method can be used to create disproportionate load on an
proxy, since stream creation is relatively inexpensive when compared
to the creation and maintenance of a TCP connection. A proxy might
also maintain some resources for a TCP connection beyond the closing
of the stream that carries the CONNECT request, since the outgoing
TCP connection remains in the TIME_WAIT state. Therefore, a proxy
cannot rely on QUIC stream limits alone to control the resources
consumed by CONNECT requests.
10.6. Use of Compression
Compression can allow an attacker to recover secret data when it is
compressed in the same context as data under attacker control.
HTTP/3 enables compression of fields (Section 4.1.1); the following
concerns also apply to the use of HTTP compressed content-codings;
see Section 6.1.2 of [SEMANTICS].
There are demonstrable attacks on compression that exploit the
characteristics of the web (e.g., [BREACH]). The attacker induces
multiple requests containing varying plaintext, observing the length
of the resulting ciphertext in each, which reveals a shorter length
when a guess about the secret is correct.
Implementations communicating on a secure channel MUST NOT compress
content that includes both confidential and attacker-controlled data
unless separate compression dictionaries are used for each source of
data. Compression MUST NOT be used if the source of data cannot be
reliably determined.
Further considerations regarding the compression of fields sections
are described in [QPACK].
10.7. Padding and Traffic Analysis
Padding can be used to obscure the exact size of frame content and is
provided to mitigate specific attacks within HTTP, for example,
attacks where compressed content includes both attacker-controlled
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
frames to make a connection more resistant to traffic analysis, frames to make a connection more resistant to traffic analysis,
HTTP/3 can either rely on transport-layer padding or employ the HTTP/3 can either rely on transport-layer padding or employ the
reserved frame and stream types discussed in Section 7.2.8 and reserved frame and stream types discussed in Section 7.2.8 and
Section 6.2.3. These methods of padding produce different results in Section 6.2.3. These methods of padding produce different results in
terms of the granularity of padding, how padding is arranged in terms of the granularity of padding, how padding is arranged in
relation to the information that is being protected, whether padding relation to the information that is being protected, whether padding
is applied in the case of packet loss, and how an implementation is applied in the case of packet loss, and how an implementation
might control padding. might control padding. Redundant padding could even be
counterproductive.
10.2. Frame Parsing To mitigate attacks that rely on compression, disabling or limiting
compression might be preferable to padding as a countermeasure.
Use of padding can result in less protection than might seem
immediately obvious. At best, padding only makes it more difficult
for an attacker to infer length information by increasing the number
of frames an attacker has to observe. Incorrectly implemented
padding schemes can be easily defeated. In particular, randomized
padding with a predictable distribution provides very little
protection; similarly, padding payloads to a fixed size exposes
information as payload sizes cross the fixed-sized boundary, which
could be possible if an attacker can control plaintext.
10.8. Frame Parsing
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.
10.3. 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.
10.4. 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.
10.11. Privacy Considerations
Several characteristics of HTTP/3 provide an observer an opportunity
to correlate actions of a single client or server over time. These
include the value of settings, the timing of reactions to stimulus,
and the handling of any features that are controlled by settings.
As far as these create observable differences in behavior, they could
be used as a basis for fingerprinting a specific client.
HTTP/3's preference for using a single QUIC connection allows
correlation of a user's activity on a site. Reusing connections for
different origins allows for correlation of activity across those
origins.
Several features of QUIC solicit immediate responses and can be used
by an endpoint to measure latency to their peer; this might have
privacy implications in certain scenarios.
11. IANA Considerations 11. IANA Considerations
This document registers a new ALPN protocol ID (Section 11.1) and This document registers a new ALPN protocol ID (Section 11.1) and
creates new registries that manage the assignment of codepoints in creates new registries that manage the assignment of codepoints in
HTTP/3. HTTP/3.
11.1. Registration of HTTP/3 Identification String 11.1. Registration of HTTP/3 Identification String
This document creates a new registration for the identification of This document creates a new registration for the identification of
HTTP/3 in the "Application Layer Protocol Negotiation (ALPN) Protocol HTTP/3 in the "Application Layer Protocol Negotiation (ALPN) Protocol
skipping to change at page 41, line 27 skipping to change at page 49, line 16
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 | 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_HEADER_LIST_SIZE | 0x6 | Section 7.2.4.1 | Unlimited | | MAX_FIELD_SECTION_SIZE | 0x6 | Section 7.2.4.1 | Unlimited |
+----------------------+-------+------------------+-----------+ +------------------------+-------+------------------+-----------+
Table 3: Initial HTTP/3 Settings Table 3: Initial HTTP/3 Settings
Additionally, each code of the format "0x1f * N + 0x21" for integer Additionally, each code of the format "0x1f * N + 0x21" for integer
values of N (that is, "0x21", "0x40", ..., through values of N (that is, "0x21", "0x40", ..., through
"0x3FFFFFFFFFFFFFFE") MUST NOT be assigned by IANA. "0x3FFFFFFFFFFFFFFE") MUST NOT be assigned by IANA.
11.2.3. Error Codes 11.2.3. Error Codes
This document establishes a registry for HTTP/3 error codes. The This document establishes a registry for HTTP/3 error codes. The
skipping to change at page 45, line 5 skipping to change at page 52, line 39
"0x3FFFFFFFFFFFFFFE") MUST NOT be assigned by IANA. "0x3FFFFFFFFFFFFFFE") MUST NOT be assigned by IANA.
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", draft-ietf-httpbis-cache-07 (work in progress),
March 2020.
[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>.
[HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>.
[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-14 (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-27 (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>.
skipping to change at page 46, line 5 skipping to change at page 53, line 38
[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>.
[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>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>.
[RFC7838] Nottingham, M., McManus, P., and J. Reschke, "HTTP [RFC7838] 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>.
[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>.
[RFC8164] Nottingham, M. and M. Thomson, "Opportunistic Security for [RFC8164] Nottingham, M. and M. Thomson, "Opportunistic Security for
HTTP/2", RFC 8164, DOI 10.17487/RFC8164, May 2017, HTTP/2", RFC 8164, DOI 10.17487/RFC8164, May 2017,
<https://www.rfc-editor.org/info/rfc8164>. <https://www.rfc-editor.org/info/rfc8164>.
[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]
Fielding, R., Nottingham, M., and J. Reschke, "HTTP
Semantics", draft-ietf-httpbis-semantics-07 (work in
progress), March 2020.
12.2. Informative References 12.2. Informative References
[BREACH] Gluck, Y., Harris, N., and A. Prado, "BREACH: Reviving the
CRIME Attack", July 2013,
<http://breachattack.com/resources/
BREACH%20-%20SSL,%20gone%20in%2030%20seconds.pdf>.
[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
Messaging", draft-ietf-httpbis-messaging-07 (work in
progress), March 2020.
[HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>.
[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>.
[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>.
[RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP [TFO] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP
Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014, Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014,
<https://www.rfc-editor.org/info/rfc7413>. <https://www.rfc-editor.org/info/rfc7413>.
[TLS13] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
12.3. URIs 12.3. URIs
[1] https://mailarchive.ietf.org/arch/search/?email_list=quic [1] https://mailarchive.ietf.org/arch/search/?email_list=quic
[2] https://github.com/quicwg [2] https://github.com/quicwg
[3] https://github.com/quicwg/base-drafts/labels/-http [3] https://github.com/quicwg/base-drafts/labels/-http
[4] https://www.iana.org/assignments/message-headers [4] https://www.iana.org/assignments/http-fields/
Appendix A. Considerations for Transitioning from HTTP/2 Appendix A. Considerations for Transitioning from HTTP/2
HTTP/3 is strongly informed by HTTP/2, and bears many similarities. HTTP/3 is strongly informed by HTTP/2, and bears many similarities.
This section describes the approach taken to design HTTP/3, points This section describes the approach taken to design HTTP/3, points
out important differences from HTTP/2, and describes how to map out important differences from HTTP/2, and describes how to map
HTTP/2 extensions into HTTP/3. HTTP/2 extensions into HTTP/3.
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
skipping to change at page 49, line 5 skipping to change at page 57, line 5
A.2.1. Prioritization Differences A.2.1. Prioritization Differences
HTTP/2 specifies priority assignments in PRIORITY frames and HTTP/2 specifies priority assignments in PRIORITY frames and
(optionally) in HEADERS frames. HTTP/3 does not provide a means of (optionally) in HEADERS frames. HTTP/3 does not provide a means of
signaling priority. signaling priority.
Note that while there is no explicit signaling for priority, this Note that while there is no explicit signaling for priority, this
does not mean that prioritization is not important for achieving good does not mean that prioritization is not important for achieving good
performance. performance.
A.2.2. Header Compression Differences A.2.2. Field Compression Differences
HPACK was designed with the assumption of in-order delivery. A HPACK was designed with the assumption of in-order delivery. A
sequence of encoded header blocks must arrive (and be decoded) at an sequence of encoded field sections must arrive (and be decoded) at an
endpoint in the same order in which they were encoded. This ensures endpoint in the same order in which they were encoded. This ensures
that the dynamic state at the two endpoints remains in sync. that the dynamic state at the two endpoints remains in sync.
Because this total ordering is not provided by QUIC, HTTP/3 uses a Because this total ordering is not provided by QUIC, HTTP/3 uses a
modified version of HPACK, called QPACK. QPACK uses a single modified version of HPACK, called QPACK. QPACK uses a single
unidirectional stream to make all modifications to the dynamic table, unidirectional stream to make all modifications to the dynamic table,
ensuring a total order of updates. All frames which contain encoded ensuring a total order of updates. All frames which contain encoded
headers merely reference the table state at a given time without fields merely reference the table state at a given time without
modifying it. modifying it.
[QPACK] provides additional details. [QPACK] provides additional details.
A.2.3. Guidance for New Frame Type Definitions A.2.3. 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 rather than a
skipping to change at page 50, line 19 skipping to change at page 58, line 19
SETTINGS (0x4): SETTINGS frames are sent only at the beginning of SETTINGS (0x4): SETTINGS frames are sent only at the beginning of
the connection. See Section 7.2.4 and Appendix A.3. the connection. See Section 7.2.4 and Appendix A.3.
PUSH_PROMISE (0x5): The PUSH_PROMISE does not reference a stream; PUSH_PROMISE (0x5): The PUSH_PROMISE does not reference a stream;
instead the push stream references the PUSH_PROMISE frame using a instead the push stream references the PUSH_PROMISE frame using a
Push ID. See Section 7.2.5. Push ID. See Section 7.2.5.
PING (0x6): PING frames do not exist, since QUIC provides equivalent PING (0x6): PING frames do not exist, since QUIC provides equivalent
functionality. functionality.
GOAWAY (0x7): GOAWAY is sent only from server to client and does not GOAWAY (0x7): GOAWAY does not contain an error code. In the client
contain an error code. See Section 7.2.6. to server direction, it carries a Push ID instead of a server
initiated stream ID. See Section 7.2.6.
WINDOW_UPDATE (0x8): WINDOW_UPDATE frames do not exist, since QUIC WINDOW_UPDATE (0x8): WINDOW_UPDATE frames do not exist, since QUIC
provides flow control. provides flow control.
CONTINUATION (0x9): CONTINUATION frames do not exist; instead, CONTINUATION (0x9): CONTINUATION frames do not exist; instead,
larger HEADERS/PUSH_PROMISE frames than HTTP/2 are permitted. larger HEADERS/PUSH_PROMISE frames than HTTP/2 are permitted.
Frame types defined by extensions to HTTP/2 need to be separately Frame types defined by extensions to HTTP/2 need to be separately
registered for HTTP/3 if still applicable. The IDs of frames defined registered for HTTP/3 if still applicable. The IDs of frames defined
in [HTTP2] have been reserved for simplicity. Note that the frame in [HTTP2] have been reserved for simplicity. Note that the frame
skipping to change at page 51, line 17 skipping to change at page 59, line 20
SETTINGS_MAX_CONCURRENT_STREAMS in the SETTINGS frame is an error. SETTINGS_MAX_CONCURRENT_STREAMS in the SETTINGS frame is an error.
SETTINGS_INITIAL_WINDOW_SIZE: QUIC requires both stream and SETTINGS_INITIAL_WINDOW_SIZE: 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 initial transport handshake. Specifying
SETTINGS_INITIAL_WINDOW_SIZE in the SETTINGS frame is an error. SETTINGS_INITIAL_WINDOW_SIZE in the SETTINGS frame is an error.
SETTINGS_MAX_FRAME_SIZE: This setting has no equivalent in HTTP/3. SETTINGS_MAX_FRAME_SIZE: This setting has no equivalent in HTTP/3.
Specifying it in the SETTINGS frame is an error. Specifying it in the SETTINGS frame is an error.
SETTINGS_MAX_HEADER_LIST_SIZE: See Section 7.2.4.1. SETTINGS_MAX_FIELD_SECTION_SIZE: See Section 7.2.4.1.
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 which use the full 32-bit space. Settings encoding for settings which 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
 End of changes. 116 change blocks. 
372 lines changed or deleted 683 lines changed or added

This html diff was produced by rfcdiff 1.44jr. The latest version is available from http://tools.ietf.org/tools/rfcdiff/