draft-ietf-quic-http-22.txt   draft-ietf-quic-http-23.txt 
QUIC M. Bishop, Ed. QUIC M. Bishop, Ed.
Internet-Draft Akamai Internet-Draft Akamai
Intended status: Standards Track July 09, 2019 Intended status: Standards Track September 12, 2019
Expires: January 10, 2020 Expires: March 15, 2020
Hypertext Transfer Protocol Version 3 (HTTP/3) Hypertext Transfer Protocol Version 3 (HTTP/3)
draft-ietf-quic-http-22 draft-ietf-quic-http-23
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
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This Internet-Draft will expire on January 10, 2020. This Internet-Draft will expire on March 15, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Prior versions of HTTP . . . . . . . . . . . . . . . . . 4 1.1. Prior versions of HTTP . . . . . . . . . . . . . . . . . 4
1.2. Delegation to QUIC . . . . . . . . . . . . . . . . . . . 4 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 . . . . . . . . . . . . . . . 6
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 . . . . . . . . . . . . . 8
3.2.1. QUIC Version Hints . . . . . . . . . . . . . . . . . 9 3.2.1. QUIC Version Hints . . . . . . . . . . . . . . . . . 9
3.3. Connection Establishment . . . . . . . . . . . . . . . . 9 3.3. Connection Establishment . . . . . . . . . . . . . . . . 10
3.4. Connection Reuse . . . . . . . . . . . . . . . . . . . . 10 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. Header Formatting and Compression . . . . . . . . . . 12
4.1.2. Request Cancellation and Rejection . . . . . . . . . 13 4.1.2. Request Cancellation and Rejection . . . . . . . . . 13
4.1.3. Malformed Requests and Responses . . . . . . . . . . 14 4.1.3. Malformed Requests and Responses . . . . . . . . . . 14
4.2. The CONNECT Method . . . . . . . . . . . . . . . . . . . 14 4.2. The CONNECT Method . . . . . . . . . . . . . . . . . . . 15
4.3. Prioritization . . . . . . . . . . . . . . . . . . . . . 15 4.3. HTTP Upgrade . . . . . . . . . . . . . . . . . . . . . . 16
4.3.1. Placeholders . . . . . . . . . . . . . . . . . . . . 17 4.4. Server Push . . . . . . . . . . . . . . . . . . . . . . . 16
4.3.2. Priority Tree Maintenance . . . . . . . . . . . . . . 17 5. Connection Closure . . . . . . . . . . . . . . . . . . . . . 17
4.4. Server Push . . . . . . . . . . . . . . . . . . . . . . . 18 5.1. Idle Connections . . . . . . . . . . . . . . . . . . . . 18
5. Connection Closure . . . . . . . . . . . . . . . . . . . . . 20 5.2. Connection Shutdown . . . . . . . . . . . . . . . . . . . 18
5.1. Idle Connections . . . . . . . . . . . . . . . . . . . . 20 5.3. Immediate Application Closure . . . . . . . . . . . . . . 19
5.2. Connection Shutdown . . . . . . . . . . . . . . . . . . . 20 5.4. Transport Closure . . . . . . . . . . . . . . . . . . . . 20
5.3. Immediate Application Closure . . . . . . . . . . . . . . 22 6. Stream Mapping and Usage . . . . . . . . . . . . . . . . . . 20
5.4. Transport Closure . . . . . . . . . . . . . . . . . . . . 22 6.1. Bidirectional Streams . . . . . . . . . . . . . . . . . . 20
6. Stream Mapping and Usage . . . . . . . . . . . . . . . . . . 22 6.2. Unidirectional Streams . . . . . . . . . . . . . . . . . 21
6.1. Bidirectional Streams . . . . . . . . . . . . . . . . . . 23 6.2.1. Control Streams . . . . . . . . . . . . . . . . . . . 22
6.2. Unidirectional Streams . . . . . . . . . . . . . . . . . 23 6.2.2. Push Streams . . . . . . . . . . . . . . . . . . . . 23
6.2.1. Control Streams . . . . . . . . . . . . . . . . . . . 24 6.2.3. Reserved Stream Types . . . . . . . . . . . . . . . . 23
6.2.2. Push Streams . . . . . . . . . . . . . . . . . . . . 25
6.2.3. Reserved Stream Types . . . . . . . . . . . . . . . . 25 7. HTTP Framing Layer . . . . . . . . . . . . . . . . . . . . . 24
7. HTTP Framing Layer . . . . . . . . . . . . . . . . . . . . . 26 7.1. Frame Layout . . . . . . . . . . . . . . . . . . . . . . 24
7.1. Frame Layout . . . . . . . . . . . . . . . . . . . . . . 27 7.2. Frame Definitions . . . . . . . . . . . . . . . . . . . . 25
7.2. Frame Definitions . . . . . . . . . . . . . . . . . . . . 28 7.2.1. DATA . . . . . . . . . . . . . . . . . . . . . . . . 25
7.2.1. DATA . . . . . . . . . . . . . . . . . . . . . . . . 28 7.2.2. HEADERS . . . . . . . . . . . . . . . . . . . . . . . 26
7.2.2. HEADERS . . . . . . . . . . . . . . . . . . . . . . . 29 7.2.3. CANCEL_PUSH . . . . . . . . . . . . . . . . . . . . . 26
7.2.3. PRIORITY . . . . . . . . . . . . . . . . . . . . . . 29 7.2.4. SETTINGS . . . . . . . . . . . . . . . . . . . . . . 27
7.2.4. CANCEL_PUSH . . . . . . . . . . . . . . . . . . . . . 32 7.2.5. PUSH_PROMISE . . . . . . . . . . . . . . . . . . . . 30
7.2.5. SETTINGS . . . . . . . . . . . . . . . . . . . . . . 32 7.2.6. GOAWAY . . . . . . . . . . . . . . . . . . . . . . . 31
7.2.6. PUSH_PROMISE . . . . . . . . . . . . . . . . . . . . 35 7.2.7. MAX_PUSH_ID . . . . . . . . . . . . . . . . . . . . . 31
7.2.7. GOAWAY . . . . . . . . . . . . . . . . . . . . . . . 36 7.2.8. DUPLICATE_PUSH . . . . . . . . . . . . . . . . . . . 32
7.2.8. MAX_PUSH_ID . . . . . . . . . . . . . . . . . . . . . 36 7.2.9. Reserved Frame Types . . . . . . . . . . . . . . . . 33
7.2.9. DUPLICATE_PUSH . . . . . . . . . . . . . . . . . . . 37 8. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 33
7.2.10. Reserved Frame Types . . . . . . . . . . . . . . . . 38 8.1. HTTP/3 Error Codes . . . . . . . . . . . . . . . . . . . 34
8. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 38 9. Extensions to HTTP/3 . . . . . . . . . . . . . . . . . . . . 35
8.1. HTTP/3 Error Codes . . . . . . . . . . . . . . . . . . . 39 10. Security Considerations . . . . . . . . . . . . . . . . . . . 36
9. Extensions to HTTP/3 . . . . . . . . . . . . . . . . . . . . 40 10.1. Traffic Analysis . . . . . . . . . . . . . . . . . . . . 36
10. Security Considerations . . . . . . . . . . . . . . . . . . . 41 10.2. Frame Parsing . . . . . . . . . . . . . . . . . . . . . 36
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 42 10.3. Early Data . . . . . . . . . . . . . . . . . . . . . . . 36
11.1. Registration of HTTP/3 Identification String . . . . . . 42 10.4. Migration . . . . . . . . . . . . . . . . . . . . . . . 37
11.2. Registration of QUIC Version Hint Alt-Svc Parameter . . 42 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37
11.3. Frame Types . . . . . . . . . . . . . . . . . . . . . . 42 11.1. Registration of HTTP/3 Identification String . . . . . . 37
11.4. Settings Parameters . . . . . . . . . . . . . . . . . . 43 11.2. Registration of QUIC Version Hint Alt-Svc Parameter . . 37
11.5. Error Codes . . . . . . . . . . . . . . . . . . . . . . 44 11.3. Frame Types . . . . . . . . . . . . . . . . . . . . . . 37
11.6. Stream Types . . . . . . . . . . . . . . . . . . . . . . 47 11.4. Settings Parameters . . . . . . . . . . . . . . . . . . 39
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 48 11.5. Error Codes . . . . . . . . . . . . . . . . . . . . . . 40
12.1. Normative References . . . . . . . . . . . . . . . . . . 48 11.6. Stream Types . . . . . . . . . . . . . . . . . . . . . . 42
12.2. Informative References . . . . . . . . . . . . . . . . . 49 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 43
12.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 50 12.1. Normative References . . . . . . . . . . . . . . . . . . 43
Appendix A. Considerations for Transitioning from HTTP/2 . . . . 50 12.2. Informative References . . . . . . . . . . . . . . . . . 44
A.1. Streams . . . . . . . . . . . . . . . . . . . . . . . . . 50 12.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 45
A.2. HTTP Frame Types . . . . . . . . . . . . . . . . . . . . 50 Appendix A. Considerations for Transitioning from HTTP/2 . . . . 45
A.2.1. Prioritization Differences . . . . . . . . . . . . . 51 A.1. Streams . . . . . . . . . . . . . . . . . . . . . . . . . 45
A.2.2. Header Compression Differences . . . . . . . . . . . 51 A.2. HTTP Frame Types . . . . . . . . . . . . . . . . . . . . 45
A.2.3. Guidance for New Frame Type Definitions . . . . . . . 52 A.2.1. Prioritization Differences . . . . . . . . . . . . . 46
A.2.4. Mapping Between HTTP/2 and HTTP/3 Frame Types . . . . 52 A.2.2. Header Compression Differences . . . . . . . . . . . 46
A.3. HTTP/2 SETTINGS Parameters . . . . . . . . . . . . . . . 53 A.2.3. Guidance for New Frame Type Definitions . . . . . . . 47
A.4. HTTP/2 Error Codes . . . . . . . . . . . . . . . . . . . 54 A.2.4. Mapping Between HTTP/2 and HTTP/3 Frame Types . . . . 47
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 55 A.3. HTTP/2 SETTINGS Parameters . . . . . . . . . . . . . . . 48
B.1. Since draft-ietf-quic-http-21 . . . . . . . . . . . . . . 55 A.4. HTTP/2 Error Codes . . . . . . . . . . . . . . . . . . . 49
B.2. Since draft-ietf-quic-http-20 . . . . . . . . . . . . . . 55 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 50
B.3. Since draft-ietf-quic-http-19 . . . . . . . . . . . . . . 56 B.1. Since draft-ietf-quic-http-22 . . . . . . . . . . . . . . 50
B.4. Since draft-ietf-quic-http-18 . . . . . . . . . . . . . . 56 B.2. Since draft-ietf-quic-http-21 . . . . . . . . . . . . . . 51
B.5. Since draft-ietf-quic-http-17 . . . . . . . . . . . . . . 57 B.3. Since draft-ietf-quic-http-20 . . . . . . . . . . . . . . 51
B.6. Since draft-ietf-quic-http-16 . . . . . . . . . . . . . . 57 B.4. Since draft-ietf-quic-http-19 . . . . . . . . . . . . . . 52
B.7. Since draft-ietf-quic-http-15 . . . . . . . . . . . . . . 58 B.5. Since draft-ietf-quic-http-18 . . . . . . . . . . . . . . 52
B.8. Since draft-ietf-quic-http-14 . . . . . . . . . . . . . . 58 B.6. Since draft-ietf-quic-http-17 . . . . . . . . . . . . . . 53
B.9. Since draft-ietf-quic-http-13 . . . . . . . . . . . . . . 58 B.7. Since draft-ietf-quic-http-16 . . . . . . . . . . . . . . 53
B.10. Since draft-ietf-quic-http-12 . . . . . . . . . . . . . . 58 B.8. Since draft-ietf-quic-http-15 . . . . . . . . . . . . . . 53
B.11. Since draft-ietf-quic-http-11 . . . . . . . . . . . . . . 59 B.9. Since draft-ietf-quic-http-14 . . . . . . . . . . . . . . 53
B.12. Since draft-ietf-quic-http-10 . . . . . . . . . . . . . . 59 B.10. Since draft-ietf-quic-http-13 . . . . . . . . . . . . . . 54
B.13. Since draft-ietf-quic-http-09 . . . . . . . . . . . . . . 59 B.11. Since draft-ietf-quic-http-12 . . . . . . . . . . . . . . 54
B.14. Since draft-ietf-quic-http-08 . . . . . . . . . . . . . . 59 B.12. Since draft-ietf-quic-http-11 . . . . . . . . . . . . . . 54
B.15. Since draft-ietf-quic-http-07 . . . . . . . . . . . . . . 59 B.13. Since draft-ietf-quic-http-10 . . . . . . . . . . . . . . 54
B.16. Since draft-ietf-quic-http-06 . . . . . . . . . . . . . . 59 B.14. Since draft-ietf-quic-http-09 . . . . . . . . . . . . . . 54
B.17. Since draft-ietf-quic-http-05 . . . . . . . . . . . . . . 59 B.15. Since draft-ietf-quic-http-08 . . . . . . . . . . . . . . 55
B.18. Since draft-ietf-quic-http-04 . . . . . . . . . . . . . . 60 B.16. Since draft-ietf-quic-http-07 . . . . . . . . . . . . . . 55
B.19. Since draft-ietf-quic-http-03 . . . . . . . . . . . . . . 60 B.17. Since draft-ietf-quic-http-06 . . . . . . . . . . . . . . 55
B.20. Since draft-ietf-quic-http-02 . . . . . . . . . . . . . . 60 B.18. Since draft-ietf-quic-http-05 . . . . . . . . . . . . . . 55
B.21. Since draft-ietf-quic-http-01 . . . . . . . . . . . . . . 60 B.19. Since draft-ietf-quic-http-04 . . . . . . . . . . . . . . 55
B.22. Since draft-ietf-quic-http-00 . . . . . . . . . . . . . . 61 B.20. Since draft-ietf-quic-http-03 . . . . . . . . . . . . . . 56
B.23. Since draft-shade-quic-http2-mapping-00 . . . . . . . . . 61 B.21. Since draft-ietf-quic-http-02 . . . . . . . . . . . . . . 56
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 61 B.22. Since draft-ietf-quic-http-01 . . . . . . . . . . . . . . 56
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 61 B.23. Since draft-ietf-quic-http-00 . . . . . . . . . . . . . . 56
B.24. Since draft-shade-quic-http2-mapping-00 . . . . . . . . . 57
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 57
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 57
1. Introduction 1. Introduction
HTTP semantics are used for a broad range of services on the HTTP semantics are used for a broad range of services on the
Internet. These semantics have commonly been used with two different Internet. These semantics have commonly been used with two different
TCP mappings, HTTP/1.1 and HTTP/2. HTTP/3 supports the same TCP mappings, HTTP/1.1 and HTTP/2. HTTP/3 supports the same
semantics over a new transport protocol, QUIC. semantics over a new transport protocol, QUIC.
1.1. Prior versions of HTTP 1.1. Prior versions of HTTP
skipping to change at page 5, line 8 skipping to change at page 5, line 14
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 at the transport layer, offering comparable
security to running TLS over TCP, with the improved connection setup security to running TLS over TCP, with the improved connection setup
latency of TCP Fast Open [RFC7413]}. latency of TCP Fast Open [RFC7413].
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 5, line 33 skipping to change at page 5, line 39
Once a client knows that an HTTP/3 server exists at a certain Once a client knows that an HTTP/3 server exists at a certain
endpoint, it opens a QUIC connection. QUIC provides protocol endpoint, it opens a QUIC connection. QUIC provides protocol
negotiation, stream-based multiplexing, and flow control. An HTTP/3 negotiation, stream-based multiplexing, and flow control. An HTTP/3
endpoint can be discovered using HTTP Alternative Services; this endpoint can be discovered using HTTP Alternative Services; this
process is described in greater detail in Section 3.2. process is described in greater detail in Section 3.2.
Within each stream, the basic unit of HTTP/3 communication is a frame Within each stream, the basic unit of HTTP/3 communication is a frame
(Section 7.2). Each frame type serves a different purpose. For (Section 7.2). Each frame type serves a different purpose. For
example, HEADERS and DATA frames form the basis of HTTP requests and example, HEADERS and DATA frames form the basis of HTTP requests and
responses (Section 4.1). Other frame types like SETTINGS, PRIORITY, responses (Section 4.1).
and GOAWAY are used to manage the overall connection and
relationships between streams.
Multiplexing of requests is performed using the QUIC stream Multiplexing of requests is performed using the QUIC stream
abstraction, described in Section 2 of [QUIC-TRANSPORT]. Each abstraction, described in Section 2 of [QUIC-TRANSPORT]. Each
request and response consumes a single QUIC stream. Streams are request and response consumes a single QUIC stream. Streams are
independent of each other, so one stream that is blocked or suffers independent of each other, so one stream that is blocked or suffers
packet loss does not prevent progress on other streams. packet loss does not prevent progress on other streams.
Server push is an interaction mode introduced in HTTP/2 [HTTP2] 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
skipping to change at page 10, line 16 skipping to change at page 10, line 22
QUIC connections are established as described in [QUIC-TRANSPORT]. QUIC connections are established as described in [QUIC-TRANSPORT].
During connection establishment, HTTP/3 support is indicated by During connection establishment, HTTP/3 support is indicated by
selecting the ALPN token "h3" in the TLS handshake. Support for selecting the ALPN token "h3" in the TLS handshake. Support for
other application-layer protocols MAY be offered in the same other application-layer protocols MAY be offered in the same
handshake. handshake.
While connection-level options pertaining to the core QUIC protocol While connection-level options pertaining to the core QUIC protocol
are set in the initial crypto handshake, HTTP/3-specific settings are are set in the initial crypto handshake, HTTP/3-specific settings are
conveyed in the SETTINGS frame. After the QUIC connection is conveyed in the SETTINGS frame. After the QUIC connection is
established, a SETTINGS frame (Section 7.2.5) 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
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.
Prior to making requests for an origin whose scheme is not "https,"
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
"http", this means that it MUST obtain a valid "http-opportunistic"
response for the origin as described in [RFC8164] prior to making any
such requests. Other schemes might define other mechanisms.
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 considerations discussed in Section 9.1 of [HTTP2] also apply to
the management of HTTP/3 connections. the management of HTTP/3 connections.
4. HTTP Request Lifecycle 4. HTTP Request Lifecycle
skipping to change at page 11, line 12 skipping to change at page 11, line 23
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 non-final 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.
An HTTP message (request or response) consists of: An HTTP message (request or response) consists of:
1. the message header (see [RFC7230], Section 3.2), sent as a single 1. the message header (see [RFC7230], Section 3.2), sent as a single
HEADERS frame (see Section 7.2.2), HEADERS frame (see Section 7.2.2),
2. the payload body (see [RFC7230], Section 3.3), sent as a series 2. optionally, the payload body, if present (see [RFC7230],
of DATA frames (see Section 7.2.1), Section 3.3), sent as a series of DATA frames (see
Section 7.2.1),
3. optionally, one HEADERS frame containing the trailer-part, if 3. optionally, trailing headers, if present (see [RFC7230],
present (see [RFC7230], Section 4.1.2). Section 4.1.2), sent as a single HEADERS frame.
A server MAY send one or more PUSH_PROMISE frames (see Section 7.2.6) 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. Section 4.4 for more details.
Frames of unknown types (Section 9), including reserved frames
(Section 7.2.9) MAY be sent on a request or push stream before,
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 4.1 of [RFC7230]
MUST NOT be used. MUST NOT be used.
If a DATA frame is received before a HEADERS frame on a either a
request or push stream, the recipient MUST respond with a connection
error of type HTTP_UNEXPECTED_FRAME (Section 8).
Trailing header fields are carried in an additional HEADERS frame
following the body. Senders MUST send only one HEADERS frame in the
trailers section; receivers MUST discard any subsequent HEADERS
frames.
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 [RFC7231], Section 6.2) more informational responses (1xx; see [RFC7231], Section 6.2)
precede a final response to the same request. Non-final responses do precede a final response to the same request. Non-final 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
request or a push stream, it MUST respond with a connection error of
type HTTP_FRAME_UNEXPECTED (Section 8). In particular, a DATA frame
before any HEADERS frame, or a HEADERS or DATA frame after the
trailing HEADERS frame is considered invalid.
An HTTP request/response exchange fully consumes a bidirectional QUIC An HTTP request/response exchange fully consumes a bidirectional QUIC
stream. After sending a request, a client MUST close the stream for stream. After sending a request, a client MUST close the stream for
sending. Unless using the CONNECT method (see Section 4.2), clients sending. Unless using the CONNECT method (see Section 4.2), clients
MUST NOT make stream closure dependent on receiving a response to MUST NOT make stream closure dependent on receiving a response to
their request. After sending a final response, the server MUST close their request. After sending a final response, the server MUST close
the stream for sending. At this point, the QUIC stream is fully the stream for sending. At this point, the QUIC stream is fully
closed. closed.
When a stream is closed, this indicates the end of an HTTP message. When a stream is closed, this indicates the end of an HTTP message.
Because some messages are large or unbounded, endpoints SHOULD begin Because some messages are large or unbounded, endpoints SHOULD begin
processing partial HTTP messages once enough of the message has been processing partial HTTP messages once enough of the message has been
received to make progress. If a client stream terminates without received to make progress. If a client stream terminates without
enough of the HTTP message to provide a complete response, the server enough of the HTTP message to provide a complete response, the server
SHOULD abort its response with the error code SHOULD abort its response with the error code
HTTP_INCOMPLETE_REQUEST. HTTP_REQUEST_INCOMPLETE.
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 this is true, a request that has not been sent and received. When this is true, a
server MAY request that the client abort transmission of a request server MAY abort reading the request stream with error code
without error by triggering a QUIC STOP_SENDING frame with error code HTTP_EARLY_RESPONSE, send a complete response, and cleanly close the
HTTP_EARLY_RESPONSE, sending a complete response, and cleanly closing sending part of the stream. Clients MUST NOT discard complete
its stream. Clients MUST NOT discard complete responses as a result responses as a result of having their request terminated abruptly,
of having their request terminated abruptly, though clients can though clients can always discard responses at their discretion for
always discard responses at their discretion for other reasons. other reasons.
4.1.1. Header Formatting and Compression 4.1.1. Header Formatting and Compression
HTTP message headers carry information as a series of key-value HTTP message headers carry information as a series of key-value
pairs, called header fields. For a listing of registered HTTP header pairs, called header fields. For a listing of registered HTTP header
fields, see the "Message Header Field" registry maintained at fields, see the "Message Header Field" registry maintained at
https://www.iana.org/assignments/message-headers [4]. https://www.iana.org/assignments/message-headers [4].
Just as in previous versions of HTTP, header field names are strings Just as in previous versions of HTTP, header field names are strings
of ASCII characters that are compared in a case-insensitive fashion. of ASCII characters that are compared in a case-insensitive fashion.
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Pseudo-header fields are not HTTP header fields. Endpoints MUST NOT Pseudo-header fields are not HTTP header fields. Endpoints MUST NOT
generate pseudo-header fields other than those defined in [HTTP2]. generate pseudo-header fields other than those defined in [HTTP2].
The restrictions on the use of pseudo-header fields in The restrictions on the use of pseudo-header fields in
Section 8.1.2.1 of [HTTP2] also apply to HTTP/3. Section 8.1.2.1 of [HTTP2] also apply to HTTP/3.
HTTP/3 uses QPACK header compression as described in [QPACK], a HTTP/3 uses QPACK header 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 header-
compression-induced head-of-line blocking. See that document for compression-induced head-of-line blocking. See that document for
additional details. additional details.
To allow for better compression efficiency, the cookie header field
[RFC6265] MAY be split into separate header fields, each with one or
more cookie-pairs, before compression. If a decompressed header list
contains multiple cookie header fields, these MUST be concatenated
before being passed into a non-HTTP/2, non-HTTP/3 context, as
described in [HTTP2], Section 8.1.2.5.
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 field list 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 header field list is calculated based on the
uncompressed size of header fields, including the length of the name uncompressed size of header fields, including the length of the name
and value in bytes plus an overhead of 32 bytes for each header and value in bytes plus an overhead of 32 bytes for each header
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_HEADER_LIST_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 aborting the stream (QUIC RESET_STREAM Clients can cancel requests by resetting and aborting the request
and/or STOP_SENDING frames, as appropriate) with an error code of stream with an error code of HTTP_REQUEST_CANCELLED (Section 8.1).
HTTP_REQUEST_CANCELLED (Section 8.1). When the client cancels a When the client aborts reading a response, it indicates that this
response, it indicates that this response is no longer of interest. response is no longer of interest. Implementations SHOULD cancel
Implementations SHOULD cancel requests by aborting both directions of requests by abruptly terminating any directions of a stream that are
a stream. still open.
When the server rejects a request without performing any application When the server rejects a request without performing any application
processing, it SHOULD abort its response stream with the error code processing, it SHOULD abort its response stream with the error code
HTTP_REQUEST_REJECTED. In this context, "processed" means that some HTTP_REQUEST_REJECTED. In this context, "processed" means that some
data from the stream was passed to some higher layer of software that data from the stream was passed to some higher layer of software that
might have taken some action as a result. The client can treat might have taken some action as a result. The client can treat
requests rejected by the server as though they had never been sent at requests rejected by the server as though they had never been sent at
all, thereby allowing them to be retried later on a new connection. all, thereby allowing them to be retried later on a new connection.
Servers MUST NOT use the HTTP_REQUEST_REJECTED error code for Servers MUST NOT use the HTTP_REQUEST_REJECTED error code for
requests which were partially or fully processed. When a server requests which were partially or fully processed. When a server
abandons a response after partial processing, it SHOULD abort its abandons a response after partial processing, it SHOULD abort its
response stream with the error code HTTP_REQUEST_CANCELLED. response stream with the error code HTTP_REQUEST_CANCELLED.
When a client sends a STOP_SENDING with HTTP_REQUEST_CANCELLED, a When a client resets a request with the error code
server MAY send the error code HTTP_REQUEST_REJECTED in the HTTP_REQUEST_CANCELLED, a server MAY abruptly terminate the response
corresponding RESET_STREAM if no processing was performed. Clients using the error code HTTP_REQUEST_REJECTED if no processing was
MUST NOT reset streams with the HTTP_REQUEST_REJECTED error code performed. Clients MUST NOT use the HTTP_REQUEST_REJECTED error
except in response to a QUIC STOP_SENDING frame that contains the code, except when a server has requested closure of the request
same code. stream with this error code.
If a stream is cancelled after receiving a complete response, the If a stream is cancelled after receiving a complete response, the
client MAY ignore the cancellation and use the response. However, if client MAY ignore the cancellation and use the response. However, if
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
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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
specifically permitted by the definition of the extension. Receipt specifically permitted by the definition of the extension. Receipt
of any other frame type MUST be treated as a connection error of type of any other frame type MUST be treated as a connection error of type
HTTP_UNEXPECTED_FRAME. HTTP_FRAME_UNEXPECTED.
The TCP connection can be closed by either peer. When the client The TCP connection can be closed by either peer. When the client
ends the request stream (that is, the receive stream at the proxy ends the request stream (that is, the receive stream at the proxy
enters the "Data Recvd" state), the proxy will set the FIN bit on its enters the "Data Recvd" state), the proxy will set the FIN bit on its
connection to the TCP server. When the proxy receives a packet with connection to the TCP server. When the proxy receives a packet with
the FIN bit set, it will terminate the send stream that it sends to the FIN bit set, it will terminate the send stream that it sends to
the client. TCP connections which remain half-closed in a single the client. TCP connections which remain half-closed in a single
direction are not invalid, but are often handled poorly by servers, direction are not invalid, but are often handled poorly by servers,
so clients SHOULD NOT close a stream for sending while they still so clients SHOULD NOT close a stream for sending while they still
expect to receive data from the target of the CONNECT. expect to receive data from the target of the CONNECT.
A TCP connection error is signaled with QUIC RESET_STREAM frame. A A TCP connection error is signaled by abruptly terminating the
proxy treats any error in the TCP connection, which includes stream. A proxy treats any error in the TCP connection, which
receiving a TCP segment with the RST bit set, as a stream error of includes receiving a TCP segment with the RST bit set, as a stream
type HTTP_CONNECT_ERROR (Section 8.1). Correspondingly, if a proxy error of type HTTP_CONNECT_ERROR (Section 8.1). Correspondingly, if
detects an error with the stream or the QUIC connection, it MUST a proxy detects an error with the stream or the QUIC connection, it
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. Prioritization 4.3. HTTP Upgrade
The purpose of prioritization is to allow a client to express how it
would prefer the server to allocate resources when managing
concurrent streams. Most importantly, priority can be used to select
streams for transmitting frames when there is limited capacity for
sending.
HTTP/3 uses a priority scheme similar to that described in [RFC7540],
Section 5.3. In this priority scheme, a given element can be
designated as dependent upon another element. Each dependency is
assigned a relative weight, a number that is used to determine the
relative proportion of available resources that are assigned to
streams dependent on the same stream. This information is expressed
in the PRIORITY frame Section 7.2.3 which identifies the element and
the dependency. The elements that can be prioritized are:
o Requests, identified by the ID of the request stream
o Pushes, identified by the Push ID of the promised resource
(Section 7.2.6)
o Placeholders, identified by a Placeholder ID
Taken together, the dependencies across all prioritized elements in a
connection form a dependency tree. An element can depend on another
element or on the root of the tree. The tree also contains an orphan
placeholder. This placeholder cannot be reprioritized, and no
resources should be allocated to descendants of the orphan
placeholder if progress can be made on descendants of the root. The
structure of the dependency tree changes as PRIORITY frames modify
the dependency links between other prioritized elements.
An exclusive flag allows for the insertion of a new level of
dependencies. The exclusive flag causes the prioritized element to
become the sole dependency of its parent, causing other dependencies
to become dependent on the exclusive element.
All dependent streams are allocated an integer weight between 1 and
256 (inclusive), derived by adding one to the weight expressed in the
PRIORITY frame.
Streams with the same parent SHOULD be allocated resources
proportionally based on their weight. Thus, if stream B depends on
stream A with weight 4, stream C depends on stream A with weight 12,
and no progress can be made on stream A, stream B ideally receives
one-third of the resources allocated to stream C.
A reference to an element which is no longer in the tree is treated
as a reference to the orphan placeholder. Due to reordering between
streams, an element can also be prioritized which is not yet in the
tree. Such elements are added to the tree with the requested
priority. If a prioritized element depends on another element which
is not yet in the tree, the requested parent is first added to the
tree with the default priority.
When a prioritized element is first created, it has a default initial
weight of 16 and a default dependency. Requests and placeholders are
dependent on the orphan placeholder; pushes are dependent on the
client request on which the PUSH_PROMISE frame was sent.
Priorities can be updated by sending a PRIORITY frame (see
Section 7.2.3) on the control stream.
4.3.1. Placeholders
In HTTP/2, certain implementations used closed or unused streams as
placeholders in describing the relative priority of requests. This
created confusion as servers could not reliably identify which
elements of the priority tree could be discarded safely. Clients
could potentially reference closed streams long after the server had
discarded state, leading to disparate views of the prioritization the
client had attempted to express.
In HTTP/3, a number of placeholders are explicitly permitted by the
server using the "SETTINGS_NUM_PLACEHOLDERS" setting. Because the
server commits to maintaining these placeholders in the
prioritization tree, clients can use them with confidence that the
server will not have discarded the state. Clients MUST NOT send the
"SETTINGS_NUM_PLACEHOLDERS" setting; receipt of this setting by a
server MUST be treated as a connection error of type
"HTTP_SETTINGS_ERROR".
Client-controlled placeholders are identified by an ID between zero
and one less than the number of placeholders the server has
permitted. The orphan placeholder cannot be prioritized or
referenced by the client.
Like streams, client-controlled placeholders have priority
information associated with them.
4.3.2. Priority Tree Maintenance
Because placeholders will be used to "root" any persistent structure
of the tree which the client cares about retaining, servers can
aggressively prune inactive regions from the priority tree. For
prioritization purposes, a node in the tree is considered "inactive"
when the corresponding stream has been closed for at least two round-
trip times (using any reasonable estimate available on the server).
This delay helps mitigate race conditions where the server has pruned
a node the client believed was still active and used as a Stream
Dependency.
Specifically, the server MAY at any time:
o Identify and discard branches of the tree containing only inactive
nodes (i.e. a node with only other inactive nodes as descendants,
along with those descendants)
o Identify and condense interior regions of the tree containing only
inactive nodes, allocating weight appropriately
x x x
| | |
P P P
/ \ | |
I I ==> I ==> A
/ \ | |
A I A A
| |
A A
Figure 1: Example of Priority Tree Pruning
In the example in Figure 1, "P" represents a Placeholder, "A"
represents an active node, and "I" represents an inactive node. In
the first step, the server discards two inactive branches (each a
single node). In the second step, the server condenses an interior
inactive node. Note that these transformations will result in no
change in the resources allocated to a particular active stream.
Clients SHOULD assume the server is actively performing such pruning HTTP/3 does not support the HTTP Upgrade mechanism ([RFC7230],
and SHOULD NOT declare a dependency on a stream it knows to have been Section 6.7) or 101 (Switching Protocols) informational status code
closed. ([RFC7231], Section 6.2.2).
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 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. HTTP/3 server off network usage against a potential latency gain. HTTP/3 server
push is similar to what is described in HTTP/2 [HTTP2], but uses push is similar to what is 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 a single PUSH_PROMISE frame (see Section 7.2.6) which carries used in a single PUSH_PROMISE frame (see Section 7.2.5) which carries
the request headers, possibly included in one or more DUPLICATE_PUSH the request headers, possibly included in one or more DUPLICATE_PUSH
frames (see Section 7.2.9), then included with the push stream which frames (see Section 7.2.8), then included with the push stream which
ultimately fulfills those promises. ultimately fulfills those promises.
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 7.2.8). 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 HTTP_ID_ERROR. error of type HTTP_ID_ERROR.
The header of the request message is carried by a PUSH_PROMISE frame The header of the request message is carried by a PUSH_PROMISE frame
(see Section 7.2.6) on the request stream which generated the push. (see Section 7.2.5) on the request stream which generated the push.
This allows the server push to be associated with a client request. This allows the server push to be associated with a client request.
Promised requests MUST conform to the requirements in Section 8.2 of Promised requests MUST conform to the requirements in Section 8.2 of
[HTTP2]. [HTTP2].
The same server push can be associated with additional client The same server push can be associated with additional client
requests using a DUPLICATE_PUSH frame (see Section 7.2.9). requests using a DUPLICATE_PUSH frame (see Section 7.2.8).
Ordering of a PUSH_PROMISE or DUPLICATE_PUSH in relation to certain Ordering of a PUSH_PROMISE or DUPLICATE_PUSH in relation to certain
parts of the response is important. The server SHOULD send parts of the response is important. The server SHOULD send
PUSH_PROMISE or DUPLICATE_PUSH frames prior to sending HEADERS or PUSH_PROMISE or DUPLICATE_PUSH frames prior to sending HEADERS or
DATA frames that reference the promised responses. This reduces the DATA frames that reference the promised responses. This reduces the
chance that a client requests a resource that will be pushed by the chance that a client requests a resource that will be pushed by the
server. server.
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
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resources and cancel the requests if the requested resource is resources and cancel the requests if the requested resource is
already being pushed. When a client receives a new push stream with already being pushed. When a client receives a new push stream with
an as-yet-unknown Push ID, both the associated client request and the an as-yet-unknown Push ID, both the associated client request and the
pushed request headers are unknown. The client can buffer the stream pushed request headers are unknown. The client can buffer the stream
data in expectation of the matching PUSH_PROMISE. The client can use data in expectation of the matching PUSH_PROMISE. The client can use
stream flow control (see section 4.1 of [QUIC-TRANSPORT]) to limit stream flow control (see section 4.1 of [QUIC-TRANSPORT]) to limit
the amount of data a server may commit to the pushed stream. the amount of data a server may 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, a QUIC STOP_SENDING or opens after sending the CANCEL_PUSH frame, the client can abort
frame with an error code of HTTP_REQUEST_CANCELLED can be used. This reading the stream with an error code of HTTP_REQUEST_CANCELLED.
asks the server not to transfer additional data and indicates that it This asks the server not to transfer additional data and indicates
will be discarded upon receipt. that it will be discarded upon receipt.
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
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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 let the connection close gracefully.
Since clients drive request generation, clients perform a connection Since clients drive request generation, clients perform a connection
shutdown by not sending additional requests on the connection; shutdown by not sending additional requests on the connection;
responses and pushed responses associated to previous requests will responses and pushed responses associated to previous requests will
continue to completion. Servers perform the same function by continue to completion. Servers perform the same function by
communicating with clients. communicating with clients.
Servers initiate the shutdown of a connection by sending a GOAWAY Servers initiate the shutdown of a connection by sending a GOAWAY
frame (Section 7.2.7). The GOAWAY frame indicates that client- frame (Section 7.2.6). The GOAWAY frame indicates that client-
initiated requests on lower stream IDs were or might be processed in initiated requests on lower stream IDs were or might be processed in
this connection, while requests on the indicated stream ID and this connection, while requests on the indicated stream ID and
greater were rejected. This enables client and server to agree on greater were rejected. This enables client and server to agree on
which requests were accepted prior to the connection shutdown. This which requests were accepted prior to the connection shutdown. This
identifier MAY be zero if no requests were processed. Servers SHOULD identifier MAY be zero if no requests were processed. Servers SHOULD
NOT increase the QUIC MAX_STREAMS limit after sending a GOAWAY frame. NOT permit additional QUIC streams after sending a GOAWAY frame.
Clients MUST NOT send new requests on the connection after receiving Clients MUST NOT send new requests on the connection after receiving
GOAWAY; a new connection MAY be established to send additional GOAWAY; a new connection MAY be established to send additional
requests. requests.
Some requests might already be in transit. If the client has already Some requests might already be in transit. If the client has already
sent requests on streams with a Stream ID greater than or equal to sent requests on streams with a Stream ID greater than or equal to
that indicated in the GOAWAY frame, those requests will not be that indicated in the GOAWAY frame, those requests will not be
processed and MAY be retried by the client on a different connection. processed and MAY be retried by the client on a different connection.
The client MAY cancel these requests. It is RECOMMENDED that the The client MAY cancel these requests. It is RECOMMENDED that the
skipping to change at page 23, line 12 skipping to change at page 20, line 49
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
stream 4, 8, and so on. In order to permit these streams to open, an stream 4, 8, and so on. In order to permit these streams to open, an
HTTP/3 client SHOULD send non-zero values for the QUIC transport HTTP/3 server SHOULD configure non-zero minimum values for the number
parameters "initial_max_stream_data_bidi_local". An HTTP/3 server of permitted streams and the initial stream flow control window. It
SHOULD send non-zero values for the QUIC transport parameters is RECOMMENDED that at least 100 requests be permitted at a time, so
"initial_max_stream_data_bidi_remote" and "initial_max_bidi_streams". as to not unnecessarily limit parallelism.
It is RECOMMENDED that "initial_max_bidi_streams" be no smaller than
100, so as to not unnecessarily limit parallelism.
HTTP/3 does not use server-initiated bidirectional streams, though an HTTP/3 does not use server-initiated bidirectional streams, though an
extension could define a use for these streams. Clients MUST treat extension could define a use for these streams. Clients MUST treat
receipt of a server-initiated bidirectional stream as a connection receipt of a server-initiated bidirectional stream as a connection
error of type HTTP_STREAM_CREATION_ERROR unless such an extension has error of type HTTP_STREAM_CREATION_ERROR unless such an extension has
been negotiated. been negotiated.
6.2. Unidirectional Streams 6.2. Unidirectional Streams
Unidirectional streams, in either direction, are used for a range of Unidirectional streams, in either direction, are used for a range of
skipping to change at page 23, line 39 skipping to change at page 21, line 25
as a variable-length integer at the start of the stream. The format as a variable-length integer at the start of the stream. The format
and structure of data that follows this integer is determined by the and structure of data that follows this integer is determined by the
stream type. stream type.
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 Type (i) ... | Stream Type (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Unidirectional Stream Header Figure 1: Unidirectional Stream Header
Some stream types are reserved (Section 6.2.3). Two stream types are Some stream types are reserved (Section 6.2.3). Two stream types are
defined in this document: control streams (Section 6.2.1) and push defined in this document: control streams (Section 6.2.1) and push
streams (Section 6.2.2). Other stream types can be defined by streams (Section 6.2.2). Other stream types can be defined by
extensions to HTTP/3; see Section 9 for more details. extensions to HTTP/3; see Section 9 for more details.
The performance of HTTP/3 connections in the early phase of their The performance of HTTP/3 connections in the early phase of their
lifetime is sensitive to the creation and exchange of data on lifetime is sensitive to the creation and exchange of data on
unidirectional streams. Endpoints that set low values for the QUIC unidirectional streams. Endpoints that excessively restrict the
transport parameters "initial_max_uni_streams" and number of streams or the flow control window of these streams will
"initial_max_stream_data_uni" will increase the chance that the increase the chance that the remote peer reaches the limit early and
remote peer reaches the limit early and becomes blocked. In becomes blocked. In particular, implementations should consider that
particular, the value chosen for "initial_max_uni_streams" should remote peers may wish to exercise reserved stream behavior
consider that remote peers may wish to exercise reserved stream (Section 6.2.3) with some of the unidirectional streams they are
behavior (Section 6.2.3). To avoid blocking, both clients and permitted to use. To avoid blocking, the transport parameters sent
servers MUST allow the peer to create at least one unidirectional by both clients and servers MUST allow the peer to create at least
stream for the HTTP control stream plus the number of unidirectional one unidirectional stream for the HTTP control stream plus the number
streams required by mandatory extensions (such as QPACK) by setting of unidirectional streams required by mandatory extensions (three
an appropriate value for the QUIC transport parameter being the minimum number required for the base HTTP/3 protocol and
"initial_max_uni_streams" (three being the minimum value required for QPACK), and SHOULD provide at least 1,024 bytes of flow control
the base HTTP/3 protocol and QPACK), and SHOULD use a value of 1,024 credit to each stream.
or greater for the QUIC transport parameter
"initial_max_stream_data_uni".
Note that an endpoint is not required to grant additional credits to Note that an endpoint is not required to grant additional credits to
create more unidirectional streams if its peer consumes all the create more unidirectional streams if its peer consumes all the
initial credits before creating the critical unidirectional streams. initial credits before creating the critical unidirectional streams.
Endpoints SHOULD create the HTTP control stream as well as the Endpoints SHOULD create the HTTP control stream as well as the
unidirectional streams required by mandatory extensions (such as the unidirectional streams required by mandatory extensions (such as the
QPACK encoder and decoder streams) first, and then create additional QPACK encoder and decoder streams) first, and then create additional
streams as allowed by their peer. streams as allowed by their peer.
If the stream header indicates a stream type which is not supported If the stream header indicates a stream type which is not supported
by the recipient, the remainder of the stream cannot be consumed as by the recipient, the remainder of the stream cannot be consumed as
the semantics are unknown. Recipients of unknown stream types MAY the semantics are unknown. Recipients of unknown stream types MAY
trigger a QUIC STOP_SENDING frame with an error code of abort reading of the stream with an error code of
HTTP_STREAM_CREATION_ERROR, but MUST NOT consider such streams to be HTTP_STREAM_CREATION_ERROR, but MUST NOT consider such streams to be
a connection error of any kind. a connection error of any kind.
Implementations MAY send stream types before knowing whether the peer Implementations MAY send stream types before knowing whether the peer
supports them. However, stream types which could modify the state or supports them. However, stream types which could modify the state or
semantics of existing protocol components, including QPACK or other semantics of existing protocol components, including QPACK or other
extensions, MUST NOT be sent until the peer is known to support them. extensions, MUST NOT be sent until the peer is known to support them.
A sender can close or reset a unidirectional stream unless otherwise A sender can close or reset a unidirectional stream unless otherwise
specified. A receiver MUST tolerate unidirectional streams being specified. A receiver MUST tolerate unidirectional streams being
skipping to change at page 25, line 26 skipping to change at page 23, line 15
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. Server push and Push IDs are described in Section 4.4. push by zero or more non-final HTTP responses followed by a single
final HTTP response, as defined in Section 4.1. Server push and Push
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
HTTP_STREAM_CREATION_ERROR. HTTP_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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x01 (i) ... | 0x01 (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Push ID (i) ... | Push ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Push Stream Header Figure 2: Push Stream Header
Each Push ID MUST only be used once in a push stream header. If a Each Push ID MUST only be used once in a push stream header. If a
push stream header includes a Push ID that was used in another push push stream header includes a Push ID that was used in another push
stream header, the client MUST treat this as a connection error of stream header, the client MUST treat this as a connection error of
type HTTP_ID_ERROR. type HTTP_ID_ERROR.
6.2.3. Reserved Stream Types 6.2.3. Reserved Stream Types
Stream types of the format "0x1f * N + 0x21" for integer values of N Stream types of the format "0x1f * N + 0x21" for integer values of N
are reserved to exercise the requirement that unknown types be are reserved to exercise the requirement that unknown types be
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7. HTTP Framing Layer 7. HTTP Framing Layer
HTTP frames are carried on QUIC streams, as described in Section 6. HTTP frames are carried on QUIC streams, as described in Section 6.
HTTP/3 defines three stream types: control stream, request stream, HTTP/3 defines three stream types: control stream, request stream,
and push stream. This section describes HTTP/3 frame formats and the and push stream. This section describes HTTP/3 frame formats and the
streams types on which they are permitted; see Table 1 for an streams types on which they are permitted; see Table 1 for an
overview. A comparison between HTTP/2 and HTTP/3 frames is provided overview. A comparison between HTTP/2 and HTTP/3 frames is provided
in Appendix A.2. in Appendix A.2.
+----------------+------------+------------+-----------+------------+ +----------------+---------+----------+---------+-------------------+
| Frame | Control | Request | Push | Section | | Frame | Control | Request | Push | Section |
| | Stream | Stream | Stream | | | | Stream | Stream | Stream | |
+----------------+------------+------------+-----------+------------+ +----------------+---------+----------+---------+-------------------+
| DATA | No | Yes | Yes | Section | | DATA | No | Yes | Yes | Section 7.2.1 |
| | | | | 7.2.1 | | | | | | |
| | | | | | | HEADERS | No | Yes | Yes | Section 7.2.2 |
| HEADERS | No | Yes | Yes | Section | | | | | | |
| | | | | 7.2.2 | | CANCEL_PUSH | Yes | No | No | Section 7.2.3 |
| | | | | | | | | | | |
| PRIORITY | Yes | No | No | Section | | SETTINGS | Yes (1) | No | No | Section 7.2.4 |
| | | | | 7.2.3 | | | | | | |
| | | | | | | PUSH_PROMISE | No | Yes | No | Section 7.2.5 |
| CANCEL_PUSH | Yes | No | No | Section | | | | | | |
| | | | | 7.2.4 | | GOAWAY | Yes | No | No | Section 7.2.6 |
| | | | | | | | | | | |
| SETTINGS | Yes (1) | No | No | Section | | MAX_PUSH_ID | Yes | No | No | Section 7.2.7 |
| | | | | 7.2.5 | | | | | | |
| | | | | | | DUPLICATE_PUSH | No | Yes | No | Section 7.2.8 |
| PUSH_PROMISE | No | Yes | No | Section | | | | | | |
| | | | | 7.2.6 | | Reserved | Yes | Yes | Yes | {{frame-reserved} |
| | | | | | +----------------+---------+----------+---------+-------------------+
| GOAWAY | Yes | No | No | Section |
| | | | | 7.2.7 |
| | | | | |
| MAX_PUSH_ID | Yes | No | No | Section |
| | | | | 7.2.8 |
| | | | | |
| DUPLICATE_PUSH | No | Yes | No | Section |
| | | | | 7.2.9 |
+----------------+------------+------------+-----------+------------+
Table 1: HTTP/3 frames and stream type overview Table 1: HTTP/3 frames and stream type overview
Certain frames can only occur as the first frame of a particular Certain frames can only occur as the first frame of a particular
stream type; these are indicated in Table 1 with a (1). Specific stream type; these are indicated in Table 1 with a (1). Specific
guidance is provided in the relevant section. guidance is provided in the relevant section.
Note that, unlike QUIC frames, HTTP/3 frames can span multiple Note that, unlike QUIC frames, HTTP/3 frames can span multiple
packets. packets.
skipping to change at page 28, line 15 skipping to change at page 25, 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (i) ... | Type (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length (i) ... | Length (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame Payload (*) ... | Frame Payload (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: HTTP/3 frame format Figure 3: HTTP/3 frame format
A frame includes the following fields: A frame includes the following fields:
Type: A variable-length integer that identifies the frame type. Type: A variable-length integer that identifies the frame type.
Length: A variable-length integer that describes the length of the Length: A variable-length integer that describes the length of the
Frame Payload. Frame Payload.
Frame Payload: A payload, the semantics of which are determined by Frame Payload: A payload, the semantics of which are determined by
the Type field. the Type field.
Each frame's payload MUST contain exactly the fields identified in Each frame's payload MUST contain exactly the fields identified in
its description. A frame payload that contains additional bytes its description. A frame payload that contains additional bytes
after the identified fields or a frame payload that terminates before after the identified fields or a frame payload that terminates before
the end of the identified fields MUST be treated as a connection the end of the identified fields MUST be treated as a connection
error of type HTTP_MALFORMED_FRAME. error of type HTTP_FRAME_ERROR.
When a stream terminates cleanly, if the last frame on the stream was When a stream terminates cleanly, if the last frame on the stream was
truncated, this MUST be treated as a connection error (Section 8) of truncated, this MUST be treated as a connection error (Section 8) of
type HTTP_MALFORMED_FRAME. Streams which terminate abruptly may be type HTTP_FRAME_ERROR. Streams which terminate abruptly may be reset
reset at any point in a frame. at any point in a frame.
7.2. Frame Definitions 7.2. Frame Definitions
7.2.1. DATA 7.2.1. DATA
DATA frames (type=0x0) convey arbitrary, variable-length sequences of DATA frames (type=0x0) convey arbitrary, variable-length sequences of
bytes associated with an HTTP request or response payload. bytes associated with an HTTP request or response payload.
DATA frames MUST be associated with an HTTP request or response. If DATA frames MUST be associated with an HTTP request or response. If
a DATA frame is received on a control stream, the recipient MUST a DATA frame is received on a control stream, the recipient MUST
respond with a connection error (Section 8) of type respond with a connection error (Section 8) of type
HTTP_WRONG_STREAM. HTTP_FRAME_UNEXPECTED.
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 5: 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 a header block,
compressed using QPACK. See [QPACK] for more details. compressed 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 (*) ... | Header Block (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: 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
HTTP_WRONG_STREAM. HTTP_FRAME_UNEXPECTED.
7.2.3. PRIORITY
The PRIORITY (type=0x2) frame specifies the client-advised priority
of a request, server push or placeholder.
A PRIORITY frame identifies an element to prioritize, and an element
upon which it depends. A Prioritized ID or Dependency ID identifies
a client-initiated request using the corresponding stream ID, a
server push using a Push ID (see Section 7.2.6), or a placeholder
using a Placeholder ID (see Section 4.3.1).
In order to ensure that prioritization is processed in a consistent
order, PRIORITY frames MUST be sent on the control stream.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|PT |DT |X|Empty| Prioritized Element ID (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Element Dependency ID (i)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weight (8) |
+-+-+-+-+-+-+-+-+
Figure 7: PRIORITY frame payload
The PRIORITY frame payload has the following fields:
PT (Prioritized Element Type): A two-bit field indicating the type
of element being prioritized (see Table 2). This MUST NOT be set
to "11".
DT (Element Dependency Type): A two-bit field indicating the type of
element being depended on (see Table 2).
X (Exclusive Flag): A single-bit flag indicating that the dependency
is exclusive (see Section 4.3).
Empty: A three-bit field which MUST be zero when sent and has no
semantic value on receipt.
Prioritized Element ID: A variable-length integer that identifies
the element being prioritized. Depending on the value of
Prioritized Type, this contains the Stream ID of a request stream,
the Push ID of a promised resource, or a Placeholder ID of a
placeholder.
Element Dependency ID: A variable-length integer that identifies the
element on which a dependency is being expressed. Depending on
the value of Dependency Type, this contains the Stream ID of a
request stream, the Push ID of a promised resource, the
Placeholder ID of a placeholder, or is absent. For details of
dependencies, see Section 4.3 and [HTTP2], Section 5.3.
Weight: An unsigned 8-bit integer representing a priority weight for
the prioritized element (see [HTTP2], Section 5.3). Add one to
the value to obtain a weight between 1 and 256.
The values for the Prioritized Element Type and Element Dependency
Type (Table 2) imply the interpretation of the associated Element ID
fields.
+-----------+------------------+---------------------+
| Type Bits | Type Description | Element ID Contents |
+-----------+------------------+---------------------+
| 00 | Request stream | Stream ID |
| | | |
| 01 | Push stream | Push ID |
| | | |
| 10 | Placeholder | Placeholder ID |
| | | |
| 11 | Root of the tree | Absent |
+-----------+------------------+---------------------+
Table 2: Element Types of a PRIORITY frame
Note that unlike in [HTTP2], the root of the tree cannot be
referenced using a Stream ID of 0, as in QUIC stream 0 carries a
valid HTTP request. The root of the tree cannot be reprioritized.
The PRIORITY frame can express relationships which might not be
permitted based on the stream on which it is sent or its position in
the stream. These situations MUST be treated as a connection error
of type HTTP_MALFORMED_FRAME. The following situations are examples
of invalid PRIORITY frames:
o A PRIORITY frame with the Prioritized Element Type set to "11".
o A PRIORITY frame which claims to reference a request, but the
associated ID does not identify a client-initiated bidirectional
stream
A PRIORITY frame with Empty bits not set to zero MAY be treated as a
connection error of type HTTP_MALFORMED_FRAME.
A PRIORITY frame that references a non-existent Push ID, a
Placeholder ID greater than the server's limit, or a Stream ID the
client is not yet permitted to open MUST be treated as a connection
error of type HTTP_ID_ERROR.
A PRIORITY frame received on any stream other than the control stream
MUST be treated as a connection error of type HTTP_WRONG_STREAM.
PRIORITY frames received by a client MUST be treated as a connection
error of type HTTP_UNEXPECTED_FRAME.
7.2.4. CANCEL_PUSH 7.2.3. CANCEL_PUSH
The CANCEL_PUSH frame (type=0x3) is used to request cancellation of a The CANCEL_PUSH frame (type=0x3) is used to request cancellation of a
server push prior to the push stream being received. The CANCEL_PUSH server push prior to the push stream being received. The CANCEL_PUSH
frame identifies a server push by Push ID (see Section 7.2.6), frame identifies a server push by Push ID (see Section 7.2.5),
encoded as a variable-length integer. encoded as a variable-length integer.
When a server receives this frame, it aborts sending the response for When a server receives this frame, it aborts sending the response for
the identified server push. If the server has not yet started to the identified server push. If the server has not yet started to
send the server push, it can use the receipt of a CANCEL_PUSH frame send the server push, it can use the receipt of a CANCEL_PUSH frame
to avoid opening a push stream. If the push stream has been opened to avoid opening a push stream. If the push stream has been opened
by the server, the server SHOULD send a QUIC RESET_STREAM frame on by the server, the server SHOULD abruptly terminate that stream.
that stream and cease transmission of the response.
A server can send the CANCEL_PUSH frame to indicate that it will not A server can send the CANCEL_PUSH frame to indicate that it will not
be fulfilling a promise prior to creation of a push stream. Once the be fulfilling a promise prior to creation of a push stream. Once the
push stream has been created, sending CANCEL_PUSH has no effect on push stream has been created, sending CANCEL_PUSH has no effect on
the state of the push stream. A QUIC RESET_STREAM frame SHOULD be the state of the push stream. The server SHOULD abruptly terminate
used instead to abort transmission of the server push response. the push stream instead.
A CANCEL_PUSH frame is sent on the control stream. Receiving a A CANCEL_PUSH frame is sent on the control stream. Receiving a
CANCEL_PUSH frame on a stream other than the control stream MUST be CANCEL_PUSH frame on a stream other than the control stream MUST be
treated as a connection error of type HTTP_WRONG_STREAM. treated as a connection error of type HTTP_FRAME_UNEXPECTED.
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) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: CANCEL_PUSH frame payload Figure 6: CANCEL_PUSH frame payload
The CANCEL_PUSH frame carries a Push ID encoded as a variable-length The CANCEL_PUSH frame carries a Push ID encoded as a variable-length
integer. The Push ID identifies the server push that is being integer. The Push ID identifies the server push that is being
cancelled (see Section 7.2.6). cancelled (see Section 7.2.5).
If the client receives a CANCEL_PUSH frame, that frame might identify If the client receives a CANCEL_PUSH frame, that frame might identify
a Push ID that has not yet been mentioned by a PUSH_PROMISE frame. a Push ID that has not yet been mentioned by a PUSH_PROMISE frame.
7.2.5. SETTINGS 7.2.4. SETTINGS
The SETTINGS frame (type=0x4) conveys configuration parameters that The SETTINGS frame (type=0x4) conveys configuration parameters that
affect how endpoints communicate, such as preferences and constraints affect how endpoints communicate, such as preferences and constraints
on peer behavior. Individually, a SETTINGS parameter can also be on peer behavior. Individually, a SETTINGS parameter can also be
referred to as a "setting"; the identifier and value of each setting referred to as a "setting"; the identifier and value of each setting
parameter can be referred to as a "setting identifier" and a "setting parameter can be referred to as a "setting identifier" and a "setting
value". value".
SETTINGS frames always apply to a connection, never a single stream. SETTINGS frames always apply to a connection, never a single stream.
A SETTINGS frame MUST be sent as the first frame of each control A SETTINGS frame MUST be sent as the first frame of each control
stream (see Section 6.2.1) by each peer, and MUST NOT be sent stream (see Section 6.2.1) by each peer, and MUST NOT be sent
subsequently. If an endpoint receives a second SETTINGS frame on the subsequently. If an endpoint receives a second SETTINGS frame on the
control stream, the endpoint MUST respond with a connection error of control stream, the endpoint MUST respond with a connection error of
type HTTP_UNEXPECTED_FRAME. type HTTP_FRAME_UNEXPECTED.
SETTINGS frames MUST NOT be sent on any stream other than the control SETTINGS frames MUST NOT be sent on any stream other than the control
stream. If an endpoint receives a SETTINGS frame on a different stream. If an endpoint receives a SETTINGS frame on a different
stream, the endpoint MUST respond with a connection error of type stream, the endpoint MUST respond with a connection error of type
HTTP_WRONG_STREAM. HTTP_FRAME_UNEXPECTED.
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 header, while servers are more cautious about request size.
Parameters MUST NOT occur more than once in the SETTINGS frame. A The same setting identifier MUST NOT occur more than once in the
receiver MAY treat the presence of the same parameter more than once SETTINGS frame. A receiver MAY treat the presence of duplicate
as a connection error of type HTTP_SETTINGS_ERROR. setting identifiers as a connection error of type
HTTP_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
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier (i) ... | Identifier (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value (i) ... | Value (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: 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.
7.2.5.1. 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_HEADER_LIST_SIZE (0x6): The default value is unlimited.
See Section 4.1.1 for usage. See Section 4.1.1 for usage.
SETTINGS_NUM_PLACEHOLDERS (0x9): The default value is 0. However,
this value SHOULD be set to a non-zero value by servers. See
Section 4.3.1 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.
Additional settings can be defined by extensions to HTTP/3; see Additional settings can be defined by extensions to HTTP/3; see
Section 9 for more details. Section 9 for more details.
7.2.5.2. Initialization 7.2.4.2. Initialization
An HTTP implementation MUST NOT send frames or requests which would An HTTP implementation MUST NOT send frames or requests which would
be invalid based on its current understanding of the peer's settings. be invalid based on its current understanding of the peer's settings.
All settings begin at an initial value, and are updated upon receipt
of a SETTINGS frame. For servers, the initial value of each client All settings begin at an initial value. Each endpoint SHOULD use
setting is the default value. these initial values to send messages before the peer's SETTINGS
frame has arrived, as packets carrying the settings can be lost or
delayed. When the SETTINGS frame arrives, any settings are changed
to their new values.
This removes the need to wait for the SETTINGS frame before sending
messages. Endpoints MUST NOT require any data to be received from
the peer prior to sending the SETTINGS frame; settings MUST be sent
as soon as the transport is ready to send data.
For servers, the initial value of each client setting is the default
value.
For clients using a 1-RTT QUIC connection, the initial value of each For clients using a 1-RTT QUIC connection, the initial value of each
server setting is the default value. When a 0-RTT QUIC connection is server setting is the default value. 1-RTT keys will always become
being used, the initial value of each server setting is the value available prior to SETTINGS arriving, even if the server sends
used in the previous session. Clients MUST store the settings the SETTINGS immediately. Clients SHOULD NOT wait indefinitely for
server provided in the session being resumed and MUST comply with SETTINGS to arrive before sending requests, but SHOULD process
stored settings until the current server settings are received. A received datagrams in order to increase the likelihood of processing
client can use these initial values to send requests before the SETTINGS before sending the first request.
server's SETTINGS frame has arrived. This removes the need for a
client to wait for the SETTINGS frame before sending requests. When a 0-RTT QUIC connection is being used, the initial value of each
server setting is the value used in the previous session. Clients
SHOULD store the settings the server provided in the connection where
resumption information was provided, but MAY opt not to store
settings in certain cases (e.g., if the session ticket is received
before the SETTINGS frame). A client MUST comply with stored
settings - or default values, if no values are stored - when
attempting 0-RTT. Once a server has provided new settings, clients
MUST comply with those values.
A server can remember the settings that it advertised, or store an A server can remember the settings that it advertised, or store an
integrity-protected copy of the values in the ticket and recover the integrity-protected copy of the values in the ticket and recover the
information when accepting 0-RTT data. A server uses the HTTP/3 information when accepting 0-RTT data. A server uses the HTTP/3
settings values in determining whether to accept 0-RTT data. settings values in determining whether to accept 0-RTT data. If the
server cannot determine that the settings remembered by a client are
compatible with its current settings, it MUST NOT accept 0-RTT data.
Remembered settings are compatible if a client complying with those
settings would not violate the server's current settings.
A server MAY accept 0-RTT and subsequently provide different settings A server MAY accept 0-RTT and subsequently provide different settings
in its SETTINGS frame. If 0-RTT data is accepted by the server, its in its SETTINGS frame. If 0-RTT data is accepted by the server, its
SETTINGS frame MUST NOT reduce any limits or alter any values that SETTINGS frame MUST NOT reduce any limits or alter any values that
might be violated by the client with its 0-RTT data. The server MAY might be violated by the client with its 0-RTT data. The server MUST
omit settings from its SETTINGS frame which are unchanged from the include all settings which differ from their default values. If a
initial value. server accepts 0-RTT, but then sends a SETTINGS frame which reduces a
setting the client understands or omits a value that was previously
specified to have a non-default value, this MUST be treated as a
connection error of type HTTP_SETTINGS_ERROR.
7.2.6. 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 set 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 (*) ... | Header Block (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: 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 7.2.4), DUPLICATE_PUSH (Section 4.4), CANCEL_PUSH frames (Section 7.2.3), and
frames (Section 7.2.9), and PRIORITY frames (Section 7.2.3). DUPLICATE_PUSH frames (Section 7.2.8).
Header Block: QPACK-compressed request header fields for the Header Block: QPACK-compressed 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 7.2.8). 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 HTTP_ID_ERROR. the client has advertised as a connection error of HTTP_ID_ERROR.
A server MUST NOT use the same Push ID in multiple PUSH_PROMISE A server MUST NOT use the same Push ID in multiple PUSH_PROMISE
frames. A client MUST treat receipt of a Push ID which has already frames. A client MUST treat receipt of a Push ID which has already
been promised as a connection error of type HTTP_ID_ERROR. been promised as a connection error of type HTTP_ID_ERROR.
If a PUSH_PROMISE frame is received on the control stream, the client If a PUSH_PROMISE frame is received on the control stream, the client
MUST respond with a connection error (Section 8) of type MUST respond with a connection error (Section 8) of type
HTTP_WRONG_STREAM. HTTP_FRAME_UNEXPECTED.
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
HTTP_UNEXPECTED_FRAME. HTTP_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.
7.2.7. 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 a server. GOAWAY allows a server to stop accepting
new requests while still finishing processing of previously received new requests while still finishing processing of previously received
requests. This enables administrative actions, like server requests. This enables administrative actions, like server
maintenance. GOAWAY by itself does not close a connection. 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 (i) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: 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. It carries a
QUIC Stream ID for a client-initiated bidirectional stream encoded as QUIC Stream ID for a client-initiated bidirectional stream encoded as
a variable-length integer. A client MUST treat receipt of a GOAWAY a variable-length integer. A client MUST treat receipt of a GOAWAY
frame containing a Stream ID of any other type as a connection error frame containing a Stream ID of any other type as a connection error
of type HTTP_MALFORMED_FRAME. of type HTTP_ID_ERROR.
Clients do not need to send GOAWAY to initiate a graceful shutdown; Clients do not need to send GOAWAY to initiate a graceful shutdown;
they simply stop making new requests. A server MUST treat receipt of they simply stop making new requests. A server MUST treat receipt of
a GOAWAY frame on any stream as a connection error (Section 8) of a GOAWAY frame on any stream as a connection error (Section 8) of
type HTTP_UNEXPECTED_FRAME. type HTTP_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 HTTP_WRONG_STREAM. stream as a connection error (Section 8) of type
HTTP_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.
7.2.8. 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
number of server pushes that the server can initiate. This sets the number of server pushes that the server can initiate. This sets the
maximum value for a Push ID that the server can use in a PUSH_PROMISE maximum value for a Push ID that the server can use in a PUSH_PROMISE
frame. Consequently, this also limits the number of push streams frame. Consequently, this also limits the number of push streams
that the server can initiate in addition to the limit set by the QUIC that the server can initiate in addition to the limit maintained by
MAX_STREAMS frame. the QUIC transport.
The MAX_PUSH_ID frame is always sent on the control stream. Receipt The MAX_PUSH_ID frame is always sent on the control stream. Receipt
of a MAX_PUSH_ID frame on any other stream MUST be treated as a of a MAX_PUSH_ID frame on any other stream MUST be treated as a
connection error of type HTTP_WRONG_STREAM. connection error of type HTTP_FRAME_UNEXPECTED.
A server MUST NOT send a MAX_PUSH_ID frame. A client MUST treat the A server MUST NOT send a MAX_PUSH_ID frame. A client MUST treat the
receipt of a MAX_PUSH_ID frame as a connection error of type receipt of a MAX_PUSH_ID frame as a connection error of type
HTTP_UNEXPECTED_FRAME. HTTP_FRAME_UNEXPECTED.
The maximum Push ID is unset when a connection is created, meaning The maximum Push ID is unset when a connection is created, meaning
that a server cannot push until it receives a MAX_PUSH_ID frame. A that a server cannot push until it receives a MAX_PUSH_ID frame. A
client that wishes to manage the number of promised server pushes can client that wishes to manage the number of promised server pushes can
increase the maximum Push ID by sending MAX_PUSH_ID frames as the increase the maximum Push ID by sending MAX_PUSH_ID frames as the
server fulfills or cancels server pushes. server fulfills or cancels server pushes.
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) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: MAX_PUSH_ID frame payload Figure 10: MAX_PUSH_ID frame payload
The MAX_PUSH_ID frame carries a single variable-length integer that The MAX_PUSH_ID frame carries a single variable-length integer that
identifies the maximum value for a Push ID that the server can use identifies the maximum value for a Push ID that the server can use
(see Section 7.2.6). A MAX_PUSH_ID frame cannot reduce the maximum (see Section 7.2.5). A MAX_PUSH_ID frame cannot reduce the maximum
Push ID; receipt of a MAX_PUSH_ID that contains a smaller value than Push ID; receipt of a MAX_PUSH_ID that contains a smaller value than
previously received MUST be treated as a connection error of type previously received MUST be treated as a connection error of type
HTTP_ID_ERROR. HTTP_ID_ERROR.
7.2.9. DUPLICATE_PUSH 7.2.8. DUPLICATE_PUSH
The DUPLICATE_PUSH frame (type=0xE) is used by servers to indicate The DUPLICATE_PUSH frame (type=0xE) is used by servers to indicate
that an existing pushed resource is related to multiple client that an existing pushed resource is related to multiple client
requests. requests.
The DUPLICATE_PUSH frame is always sent on a request stream. Receipt The DUPLICATE_PUSH frame is always sent on a request stream. Receipt
of a DUPLICATE_PUSH frame on any other stream MUST be treated as a of a DUPLICATE_PUSH frame on any other stream MUST be treated as a
connection error of type HTTP_WRONG_STREAM. connection error of type HTTP_FRAME_UNEXPECTED.
A client MUST NOT send a DUPLICATE_PUSH frame. A server MUST treat A client MUST NOT send a DUPLICATE_PUSH frame. A server MUST treat
the receipt of a DUPLICATE_PUSH frame as a connection error of type the receipt of a DUPLICATE_PUSH frame as a connection error of type
HTTP_UNEXPECTED_FRAME. HTTP_FRAME_UNEXPECTED.
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) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: DUPLICATE_PUSH frame payload Figure 11: DUPLICATE_PUSH frame payload
The DUPLICATE_PUSH frame carries a single variable-length integer The DUPLICATE_PUSH frame carries a single variable-length integer
that identifies the Push ID of a resource that the server has that identifies the Push ID of a resource that the server has
previously promised (see Section 7.2.6), though that promise might previously promised (see Section 7.2.5), though that promise might
not be received before this frame. A server MUST NOT use a Push ID not be received before this frame. A server MUST NOT use a Push ID
that is larger than the client has provided in a MAX_PUSH_ID frame that is larger than the client has provided in a MAX_PUSH_ID frame
(Section 7.2.8). A client MUST treat receipt of a DUPLICATE_PUSH (Section 7.2.7). A client MUST treat receipt of a DUPLICATE_PUSH
that contains a larger Push ID than the client has advertised as a that contains a larger Push ID than the client has advertised as a
connection error of type HTTP_ID_ERROR. connection error of type HTTP_ID_ERROR.
This frame allows the server to use the same server push in response This frame allows the server to use the same server push in response
to multiple concurrent requests. Referencing the same server push to multiple concurrent requests. Referencing the same server push
ensures that a promise can be made in relation to every response in ensures that a promise can be made in relation to every response in
which server push might be needed without duplicating request headers which server push might be needed without duplicating request headers
or pushed responses. or pushed responses.
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 DUPLICATE_PUSH that uses a Push ID that time. Clients that see a DUPLICATE_PUSH that uses a Push ID that
they have since consumed and discarded are forced to ignore the they have since consumed and discarded are forced to ignore the
DUPLICATE_PUSH. DUPLICATE_PUSH.
7.2.10. Reserved Frame Types 7.2.9. Reserved Frame Types
Frame types of the format "0x1f * N + 0x21" for integer values of N Frame types of the format "0x1f * N + 0x21" for integer values of N
are reserved to exercise the requirement that unknown types be are reserved to exercise the requirement that unknown types be
ignored (Section 9). These frames have no semantics, and can be sent ignored (Section 9). These frames have no semantics, and can be sent
when application-layer padding is desired. They MAY also be sent on on any open stream when application-layer padding is desired. They
connections where no data is currently being transferred. Endpoints MAY also be sent on connections where no data is currently being
MUST NOT consider these frames to have any meaning upon receipt. transferred. Endpoints MUST NOT consider these frames to have any
meaning upon receipt.
The payload and length of the frames are selected in any manner the The payload and length of the frames are selected in any manner the
implementation chooses. implementation chooses.
Frame types which were used in HTTP/2 where there is no corresponding
HTTP/3 frame have also been reserved (Section 11.3). These frame
types MUST NOT be sent, and receipt MAY be treated as an error of
type HTTP_UNEXPECTED_FRAME.
8. Error Handling 8. Error Handling
QUIC allows the application to abruptly terminate (reset) individual QUIC allows the application to abruptly terminate (reset) individual
streams or the entire connection when an error is encountered. These streams or the entire connection when an error is encountered. These
are referred to as "stream errors" or "connection errors" and are are referred to as "stream errors" or "connection errors" and are
described in more detail in [QUIC-TRANSPORT]. An endpoint MAY choose described in more detail in [QUIC-TRANSPORT]. An endpoint MAY choose
to treat a stream error as a connection error. to treat a stream error as a connection error.
Because new error codes can be defined without negotiation (see
Section 9), receipt of an unknown error code or use of an error code
in an unexpected context MUST NOT be treated as an error. However,
closing a stream can constitute an error regardless of the error code
(see Section 4.1).
This section describes HTTP/3-specific error codes which can be used This section describes HTTP/3-specific error codes which can be used
to express the cause of a connection or stream error. to express the cause of a connection or stream error.
8.1. HTTP/3 Error Codes 8.1. HTTP/3 Error Codes
The following error codes are defined for use in QUIC RESET_STREAM The following error codes are defined for use when abruptly
frames, STOP_SENDING frames, and CONNECTION_CLOSE frames when using terminating streams, aborting reading of streams, or immediately
HTTP/3. closing connections.
HTTP_NO_ERROR (0x00): No error. This is used when the connection or HTTP_NO_ERROR (0x100): No error. This is used when the connection
stream needs to be closed, but there is no error to signal. or stream needs to be closed, but there is no error to signal.
HTTP_GENERAL_PROTOCOL_ERROR (0x01): Peer violated protocol HTTP_GENERAL_PROTOCOL_ERROR (0x101): Peer violated protocol
requirements in a way which doesn't match a more specific error requirements in a way which doesn't match a more specific error
code, or endpoint declines to use the more specific error code. code, or endpoint declines to use the more specific error code.
Reserved (0x02): This code is reserved and has no meaning. HTTP_INTERNAL_ERROR (0x102): An internal error has occurred in the
HTTP_INTERNAL_ERROR (0x03): An internal error has occurred in the
HTTP stack. HTTP stack.
Reserved (0x04): This code is reserved and has no meaning. HTTP_STREAM_CREATION_ERROR (0x103): The endpoint detected that its
peer created a stream that it will not accept.
HTTP_REQUEST_CANCELLED (0x05): The request or its response HTTP_CLOSED_CRITICAL_STREAM (0x104): A stream required by the
(including pushed response) is cancelled. connection was closed or reset.
HTTP_INCOMPLETE_REQUEST (0x06): The client's stream terminated HTTP_FRAME_UNEXPECTED (0x105): A frame was received which was not
without containing a fully-formed request. permitted in the current state or on the current stream.
HTTP_CONNECT_ERROR (0x07): The connection established in response to HTTP_FRAME_ERROR (0x106): A frame that fails to satisfy layout
a CONNECT request was reset or abnormally closed. requirements or with an invalid size was received.
HTTP_EXCESSIVE_LOAD (0x08): The endpoint detected that its peer is HTTP_EXCESSIVE_LOAD (0x107): The endpoint detected that its peer is
exhibiting a behavior that might be generating excessive load. exhibiting a behavior that might be generating excessive load.
HTTP_VERSION_FALLBACK (0x09): The requested operation cannot be HTTP_ID_ERROR (0x108): A Stream ID or Push ID was used incorrectly,
served over HTTP/3. The peer should retry over HTTP/1.1. such as exceeding a limit, reducing a limit, or being reused.
HTTP_WRONG_STREAM (0x0A): A frame was received on a stream where it
is not permitted.
HTTP_ID_ERROR (0x0B): A Stream ID, Push ID, or Placeholder ID was HTTP_SETTINGS_ERROR (0x109): An endpoint detected an error in the
used incorrectly, such as exceeding a limit, reducing a limit, or payload of a SETTINGS frame.
being reused.
Reserved (0x0C): N/A HTTP_MISSING_SETTINGS (0x10A): No SETTINGS frame was received at the
beginning of the control stream.
HTTP_STREAM_CREATION_ERROR (0x0D): The endpoint detected that its HTTP_REQUEST_REJECTED (0x10B): A server rejected a request without
peer created a stream that it will not accept. performing any application processing.
Reserved (0x0E): N/A HTTP_REQUEST_CANCELLED (0x10C): The request or its response
HTTP_CLOSED_CRITICAL_STREAM (0x0F): A stream required by the (including pushed response) is cancelled.
connection was closed or reset.
Reserved (0x0010): N/A HTTP_REQUEST_INCOMPLETE (0x10D): The client's stream terminated
without containing a fully-formed request.
HTTP_EARLY_RESPONSE (0x0011): The remainder of the client's request HTTP_EARLY_RESPONSE (0x10E): The remainder of the client's request
is not needed to produce a response. For use in STOP_SENDING is not needed to produce a response. For use in STOP_SENDING
only. only.
HTTP_MISSING_SETTINGS (0x0012): No SETTINGS frame was received at HTTP_CONNECT_ERROR (0x10F): The connection established in response
the beginning of the control stream. to a CONNECT request was reset or abnormally closed.
HTTP_UNEXPECTED_FRAME (0x0013): A frame was received which was not
permitted in the current state.
HTTP_REQUEST_REJECTED (0x0014): A server rejected a request without
performing any application processing.
HTTP_SETTINGS_ERROR (0x00FF): An endpoint detected an error in the
payload of a SETTINGS frame: a duplicate setting was detected, a
client-only setting was sent by a server, or a server-only setting
by a client.
HTTP_MALFORMED_FRAME (0x01XX): An error in a specific frame type. HTTP_VERSION_FALLBACK (0x110): The requested operation cannot be
If the frame type is "0xfe" or less, the type is included as the served over HTTP/3. The peer should retry over HTTP/1.1.
last byte of the error code. For example, an error in a
MAX_PUSH_ID frame would be indicated with the code (0x10D). The
last byte "0xff" is used to indicate any frame type greater than
"0xfe".
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 header 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 7.2.5.1), 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 11.3), settings (Section 11.4), error codes (Section 11.5), (Section 11.3), settings (Section 11.4), error codes (Section 11.5),
and stream types (Section 11.6). and stream types (Section 11.6).
Implementations MUST ignore unknown or unsupported values in all Implementations MUST ignore unknown or unsupported values in all
extensible protocol elements. Implementations MUST discard frames extensible protocol elements. Implementations MUST discard frames
and unidirectional streams that have unknown or unsupported types. and unidirectional streams that have unknown or unsupported types.
This means that any of these extension points can be safely used by This means that any of these extension points can be safely used by
extensions without prior arrangement or negotiation. extensions without prior arrangement or negotiation. However, where
a known frame type is required to be in a specific location, such as
the SETTINGS frame as the first frame of the control stream (see
Section 6.2.1), an unknown frame type does not satisfy that
requirement and SHOULD be treated as an error.
Extensions that could change the semantics of existing protocol Extensions that could change the semantics of existing protocol
components MUST be negotiated before being used. For example, an components MUST be negotiated before being used. For example, an
extension that changes the layout of the HEADERS frame cannot be used extension that changes the layout of the HEADERS frame cannot be used
until the peer has given a positive signal that this is acceptable. until the peer has given a positive signal that this is acceptable.
In this case, it could also be necessary to coordinate when the In this case, it could also be necessary to coordinate when the
revised layout comes into effect. revised layout comes into effect.
This document doesn't mandate a specific method for negotiating the This document doesn't mandate a specific method for negotiating the
use of an extension but notes that a setting (Section 7.2.5.1) 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. Note that where HTTP/2 employs PADDING frames of HTTP/2 with TLS; the considerations from Section 10 of [HTTP2]
and Padding fields in other frames to make a connection more apply in addition to those listed here.
resistant to traffic analysis, HTTP/3 can rely on QUIC PADDING frames
or employ the reserved frame and stream types discussed in
Section 7.2.10 and Section 6.2.3.
When HTTP Alternative Services is used for discovery for HTTP/3 When HTTP Alternative Services is used for discovery for HTTP/3
endpoints, the security considerations of [ALTSVC] also apply. endpoints, the security considerations of [ALTSVC] also apply.
10.1. Traffic Analysis
Where HTTP/2 employs PADDING frames and Padding fields in other
frames to make a connection more resistant to traffic analysis,
HTTP/3 can either rely on transport-layer padding or employ the
reserved frame and stream types discussed in Section 7.2.9 and
Section 6.2.3. These methods of padding produce different results in
terms of the granularity of padding, the effect of packet loss and
recovery, and how an implementation might control padding.
10.2. 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
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
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.
11. IANA Considerations 11. IANA Considerations
skipping to change at page 43, line 20 skipping to change at page 38, line 27
The entries in the following table are registered by this document. The entries in the following table are registered by this document.
+----------------+------+---------------+ +----------------+------+---------------+
| Frame Type | Code | Specification | | Frame Type | Code | Specification |
+----------------+------+---------------+ +----------------+------+---------------+
| DATA | 0x0 | Section 7.2.1 | | DATA | 0x0 | Section 7.2.1 |
| | | | | | | |
| HEADERS | 0x1 | Section 7.2.2 | | HEADERS | 0x1 | Section 7.2.2 |
| | | | | | | |
| PRIORITY | 0x2 | Section 7.2.3 | | Reserved | 0x2 | N/A |
| | | | | | | |
| CANCEL_PUSH | 0x3 | Section 7.2.4 | | CANCEL_PUSH | 0x3 | Section 7.2.3 |
| | | | | | | |
| SETTINGS | 0x4 | Section 7.2.5 | | SETTINGS | 0x4 | Section 7.2.4 |
| | | | | | | |
| PUSH_PROMISE | 0x5 | Section 7.2.6 | | PUSH_PROMISE | 0x5 | Section 7.2.5 |
| | | | | | | |
| Reserved | 0x6 | N/A | | Reserved | 0x6 | N/A |
| | | | | | | |
| GOAWAY | 0x7 | Section 7.2.7 | | GOAWAY | 0x7 | Section 7.2.6 |
| | | | | | | |
| Reserved | 0x8 | N/A | | Reserved | 0x8 | N/A |
| | | | | | | |
| Reserved | 0x9 | N/A | | Reserved | 0x9 | N/A |
| | | | | | | |
| MAX_PUSH_ID | 0xD | Section 7.2.8 | | MAX_PUSH_ID | 0xD | Section 7.2.7 |
| | | | | | | |
| DUPLICATE_PUSH | 0xE | Section 7.2.9 | | DUPLICATE_PUSH | 0xE | Section 7.2.8 |
+----------------+------+---------------+ +----------------+------+---------------+
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.
11.4. Settings Parameters 11.4. Settings Parameters
This document establishes a registry for HTTP/3 settings. The This document establishes a registry for HTTP/3 settings. The
"HTTP/3 Settings" registry governs a 62-bit space. This space is "HTTP/3 Settings" registry governs a 62-bit space. This space is
skipping to change at page 44, line 4 skipping to change at page 39, line 13
"0x3FFFFFFFFFFFFFFE") MUST NOT be assigned by IANA. "0x3FFFFFFFFFFFFFFE") MUST NOT be assigned by IANA.
11.4. Settings Parameters 11.4. Settings Parameters
This document establishes a registry for HTTP/3 settings. The This document establishes a registry for HTTP/3 settings. The
"HTTP/3 Settings" registry governs a 62-bit space. This space is "HTTP/3 Settings" registry governs a 62-bit space. This space is
split into three spaces that are governed by different policies. split into three spaces that are governed by different policies.
Values between "0x00" and "0x3f" (in hexadecimal) are assigned via Values between "0x00" and "0x3f" (in hexadecimal) are assigned via
the Standards Action or IESG Review policies [RFC8126]. Values from the Standards Action or IESG Review policies [RFC8126]. Values from
"0x40" to "0x3fff" operate on the Specification Required policy "0x40" to "0x3fff" operate on the Specification Required policy
[RFC8126]. All other values are assigned to Private Use [RFC8126]. [RFC8126]. All other values are assigned to Private Use [RFC8126].
The designated experts are the same as those for the "HTTP/2 The designated experts are the same as those for the "HTTP/2
Settings" registry defined in [HTTP2]. Settings" registry defined in [HTTP2].
While this registry is separate from the "HTTP/2 Settings" registry While this registry is separate from the "HTTP/2 Settings" registry
defined in [HTTP2], it is preferable that the assignments parallel defined in [HTTP2], it is preferable that the assignments parallel
each other. If an entry is present in only one registry, every each other. If an entry is present in only one registry, every
effort SHOULD be made to avoid assigning the corresponding value to effort SHOULD be made to avoid assigning the corresponding value to
an unrelated operation. an unrelated operation.
New registrations are advised to provide the following information: New registrations are advised to provide the following information:
Name: A symbolic name for the setting. Specifying a setting name is Name: A symbolic name for the setting. Specifying a setting name is
optional. optional.
Code: The 62-bit code assigned to the setting. Code: The 62-bit code assigned to the setting.
Specification: An optional reference to a specification that Specification: An optional reference to a specification that
describes the use of the setting. describes the use of the setting.
Default: The value of the setting unless otherwise indicated.
SHOULD be the most restrictive possible value.
The entries in the following table are registered by this document. The entries in the following table are registered by this document.
+----------------------+------+-----------------+ +----------------------+------+-----------------+-----------+
| Setting Name | Code | Specification | | Setting Name | Code | Specification | Default |
+----------------------+------+-----------------+ +----------------------+------+-----------------+-----------+
| Reserved | 0x2 | N/A | | Reserved | 0x2 | N/A | N/A |
| | | | | | | | |
| Reserved | 0x3 | N/A | | Reserved | 0x3 | N/A | N/A |
| | | | | | | | |
| Reserved | 0x4 | N/A | | Reserved | 0x4 | N/A | N/A |
| | | | | | | | |
| Reserved | 0x5 | N/A | | Reserved | 0x5 | N/A | N/A |
| | | | | | | | |
| MAX_HEADER_LIST_SIZE | 0x6 | Section 7.2.5.1 | | MAX_HEADER_LIST_SIZE | 0x6 | Section 7.2.4.1 | Unlimited |
| | | | +----------------------+------+-----------------+-----------+
| NUM_PLACEHOLDERS | 0x9 | Section 7.2.5.1 |
+----------------------+------+-----------------+
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.
11.5. Error Codes 11.5. Error Codes
This document establishes a registry for HTTP/3 error codes. The This document establishes a registry for HTTP/3 error codes. The
"HTTP/3 Error Code" registry manages a 62-bit space. The "HTTP/3 "HTTP/3 Error Code" registry manages a 62-bit space. The "HTTP/3
Error Code" registry operates under the "Expert Review" policy Error Code" registry operates under the "Expert Review" policy
skipping to change at page 45, line 28 skipping to change at page 40, line 39
if no detailed specification is provided. if no detailed specification is provided.
Specification: An optional reference for a specification that Specification: An optional reference for a specification that
defines the error code. defines the error code.
The entries in the following table are registered by this document. The entries in the following table are registered by this document.
+----------------------------+--------+-------------+---------------+ +----------------------------+--------+-------------+---------------+
| Name | Code | Description | Specification | | Name | Code | Description | Specification |
+----------------------------+--------+-------------+---------------+ +----------------------------+--------+-------------+---------------+
| HTTP_NO_ERROR | 0x0000 | No error | Section 8.1 | | HTTP_NO_ERROR | 0x0100 | No error | Section 8.1 |
| | | | | | | | | |
| HTTP_GENERAL_PROTOCOL_ERRO | 0x0001 | General | Section 8.1 | | HTTP_GENERAL_PROTOCOL_ERRO | 0x0101 | General | Section 8.1 |
| R | | protocol | | | R | | protocol | |
| | | error | | | | | error | |
| | | | | | | | | |
| Reserved | 0x0002 | N/A | N/A | | HTTP_INTERNAL_ERROR | 0x0102 | Internal | Section 8.1 |
| | | | |
| HTTP_INTERNAL_ERROR | 0x0003 | Internal | Section 8.1 |
| | | error | | | | | error | |
| | | | | | | | | |
| Reserved | 0x0004 | N/A | N/A | | HTTP_STREAM_CREATION_ERROR | 0x0103 | Stream | Section 8.1 |
| | | creation | |
| | | error | |
| | | | | | | | | |
| HTTP_REQUEST_CANCELLED | 0x0005 | Data no | Section 8.1 | | HTTP_CLOSED_CRITICAL_STREA | 0x0104 | Critical | Section 8.1 |
| | | longer | | | M | | stream was | |
| | | needed | | | | | closed | |
| | | | | | | | | |
| HTTP_INCOMPLETE_REQUEST | 0x0006 | Stream | Section 8.1 | | HTTP_FRAME_UNEXPECTED | 0x0105 | Frame not | Section 8.1 |
| | | terminated | | | | | permitted | |
| | | early | | | | | in the | |
| | | current | |
| | | state | |
| | | | | | | | | |
| HTTP_CONNECT_ERROR | 0x0007 | TCP reset | Section 8.1 | | HTTP_FRAME_ERROR | 0x0106 | Frame | Section 8.1 |
| | | or error on | | | | | violated | |
| | | CONNECT | | | | | layout or | |
| | | request | | | | | size rules | |
| | | | | | | | | |
| HTTP_EXCESSIVE_LOAD | 0x0008 | Peer | Section 8.1 | | HTTP_EXCESSIVE_LOAD | 0x0107 | Peer | Section 8.1 |
| | | generating | | | | | generating | |
| | | excessive | | | | | excessive | |
| | | load | | | | | load | |
| | | | | | | | | |
| HTTP_VERSION_FALLBACK | 0x0009 | Retry over | Section 8.1 | | HTTP_ID_ERROR | 0x0108 | An | Section 8.1 |
| | | HTTP/1.1 | |
| | | | |
| HTTP_WRONG_STREAM | 0x000A | A frame was | Section 8.1 |
| | | sent on the | |
| | | wrong | |
| | | stream | |
| | | | |
| HTTP_ID_ERROR | 0x000B | An | Section 8.1 |
| | | identifier | | | | | identifier | |
| | | was used | | | | | was used | |
| | | incorrectly | | | | | incorrectly | |
| | | | | | | | | |
| Reserved | 0x000C | N/A | N/A | | HTTP_SETTINGS_ERROR | 0x0109 | SETTINGS | Section 8.1 |
| | | frame | |
| | | contained | |
| | | invalid | |
| | | values | |
| | | | | | | | | |
| HTTP_STREAM_CREATION_ERROR | 0x000D | Stream | Section 8.1 | | HTTP_MISSING_SETTINGS | 0x010A | No SETTINGS | Section 8.1 |
| | | creation | | | | | frame | |
| | | error | | | | | received | |
| | | | | | | | | |
| Reserved | 0x000E | N/A | N/A | | HTTP_REQUEST_REJECTED | 0x010B | Request not | Section 8.1 |
| | | processed | |
| | | | | | | | | |
| HTTP_CLOSED_CRITICAL_STREA | 0x000F | Critical | Section 8.1 | | HTTP_REQUEST_CANCELLED | 0x010C | Data no | Section 8.1 |
| M | | stream was | | | | | longer | |
| | | closed | | | | | needed | |
| | | | | | | | | |
| Reserved | 0x000E | N/A | N/A | | HTTP_REQUEST_INCOMPLETE | 0x010D | Stream | Section 8.1 |
| | | terminated | |
| | | early | |
| | | | | | | | | |
| HTTP_EARLY_RESPONSE | 0x0011 | Remainder | Section 8.1 | | HTTP_EARLY_RESPONSE | 0x010E | Remainder | Section 8.1 |
| | | of request | | | | | of request | |
| | | not needed | | | | | not needed | |
| | | | | | | | | |
| HTTP_MISSING_SETTINGS | 0x0012 | No SETTINGS | Section 8.1 | | HTTP_CONNECT_ERROR | 0x010F | TCP reset | Section 8.1 |
| | | frame | | | | | or error on | |
| | | received | | | | | CONNECT | |
| | | | | | | | request | |
| HTTP_UNEXPECTED_FRAME | 0x0013 | Frame not | Section 8.1 |
| | | permitted | |
| | | in the | |
| | | current | |
| | | state | |
| | | | |
| HTTP_REQUEST_REJECTED | 0x0014 | Request not | Section 8.1 |
| | | processed | |
| | | | |
| HTTP_MALFORMED_FRAME | 0x01XX | Error in | Section 8.1 |
| | | frame | |
| | | formatting | |
| | | | | | | | | |
| HTTP_SETTINGS_ERROR | 0x00FF | SETTINGS | Section 8.1 | | HTTP_VERSION_FALLBACK | 0x0110 | Retry over | Section 8.1 |
| | | frame | | | | | HTTP/1.1 | |
| | | contained | |
| | | invalid | |
| | | values | |
+----------------------------+--------+-------------+---------------+ +----------------------------+--------+-------------+---------------+
11.6. Stream Types 11.6. Stream Types
This document establishes a registry for HTTP/3 unidirectional stream This document establishes a registry for HTTP/3 unidirectional stream
types. The "HTTP/3 Stream Type" registry governs a 62-bit space. types. The "HTTP/3 Stream Type" registry governs a 62-bit space.
This space is split into three spaces that are governed by different This space is split into three spaces that are governed by different
policies. Values between "0x00" and 0x3f (in hexadecimal) are policies. Values between "0x00" and 0x3f (in hexadecimal) are
assigned via the Standards Action or IESG Review policies [RFC8126]. assigned via the Standards Action or IESG Review policies [RFC8126].
Values from "0x40" to "0x3fff" operate on the Specification Required Values from "0x40" to "0x3fff" operate on the Specification Required
skipping to change at page 48, line 29 skipping to change at page 43, line 25
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 [HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540, Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015, DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>. <https://www.rfc-editor.org/info/rfc7540>.
[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-10 (work in progress), July 2019. qpack-10 (work in progress), September 2019.
[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-22 (work in progress), July 2019. transport-23 (work in progress), September 2019.
[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>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008, DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>. <https://www.rfc-editor.org/info/rfc5234>.
[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,
DOI 10.17487/RFC6265, April 2011,
<https://www.rfc-editor.org/info/rfc6265>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing", Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014, RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>. <https://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231, Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014, DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>. <https://www.rfc-editor.org/info/rfc7231>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>.
[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
HTTP/2", RFC 8164, DOI 10.17487/RFC8164, May 2017,
<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>.
12.2. Informative References 12.2. Informative References
[HPACK] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [HPACK] Peon, R. and H. Ruellan, "HPACK: Header Compression for
Protocol (HTTP/1.1): Semantics and Content", RFC 7231, HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015,
DOI 10.17487/RFC7231, June 2014, <https://www.rfc-editor.org/info/rfc7541>.
<https://www.rfc-editor.org/info/rfc7231>.
[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>.
skipping to change at page 51, line 29 skipping to change at page 46, line 29
type makes assumptions that frames from different streams will still type makes assumptions that frames from different streams will still
be received in the order sent, HTTP/3 will break them. be received in the order sent, HTTP/3 will break them.
Some examples of feature adaptations are described below, as well as Some examples of feature adaptations are described below, as well as
general guidance to extension frame implementors converting an HTTP/2 general guidance to extension frame implementors converting an HTTP/2
extension to HTTP/3. extension to HTTP/3.
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. Implicit in the HTTP/2 (optionally) in HEADERS frames. HTTP/3 does not provide a means of
prioritization scheme is the notion of in-order delivery of priority signaling priority.
changes (i.e., dependency tree mutations). Since operations on the
dependency tree such as reparenting a subtree are not commutative,
both sender and receiver must apply them in the same order to ensure
that both sides have a consistent view of the stream dependency tree.
To achieve in-order delivery of priority changes in HTTP/3, PRIORITY Note that while there is no explicit signaling for priority, this
frames are sent on the control stream. HTTP/3 permits the does not mean that prioritization is not important for achieving good
prioritization of requests, pushes and placeholders that each exist performance.
in separate identifier spaces. The HTTP/3 PRIORITY frame replaces
the stream dependency field with fields that can identify the element
of interest and its dependency.
A.2.2. Header Compression Differences A.2.2. Header 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 header blocks 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
skipping to change at page 52, line 17 skipping to change at page 47, line 11
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
Stream ID (e.g. Push IDs in PRIORITY frames). Redefinition of the Stream ID (e.g., Push IDs). Redefinition of the encoding of
encoding of extension frame types might be necessary if the encoding extension frame types might be necessary if the encoding includes a
includes a Stream ID. Stream ID.
Because the Flags field is not present in generic HTTP/3 frames, Because the Flags field is not present in generic HTTP/3 frames,
those frames which depend on the presence of flags need to allocate those frames which depend on the presence of flags need to allocate
space for flags as part of their frame payload. space for flags as part of their frame payload.
Other than this issue, frame type HTTP/2 extensions are typically Other than this issue, frame type HTTP/2 extensions are typically
portable to QUIC simply by replacing Stream 0 in HTTP/2 with a portable to QUIC simply by replacing Stream 0 in HTTP/2 with a
control stream in HTTP/3. HTTP/3 extensions will not assume control stream in HTTP/3. HTTP/3 extensions will not assume
ordering, but would not be harmed by ordering, and would be portable ordering, but would not be harmed by ordering, and would be portable
to HTTP/2 in the same manner. to HTTP/2 in the same manner.
A.2.4. Mapping Between HTTP/2 and HTTP/3 Frame Types A.2.4. Mapping Between HTTP/2 and HTTP/3 Frame Types
DATA (0x0): Padding is not defined in HTTP/3 frames. See DATA (0x0): Padding is not defined in HTTP/3 frames. See
Section 7.2.1. Section 7.2.1.
HEADERS (0x1): The PRIORITY region of HEADERS is not defined in HEADERS (0x1): The PRIORITY region of HEADERS is not defined in
HTTP/3 frames. A separate PRIORITY frame is used in all cases. HTTP/3 frames. Padding is not defined in HTTP/3 frames. See
Padding is not defined in HTTP/3 frames. See Section 7.2.2. Section 7.2.2.
PRIORITY (0x2): As described above, the PRIORITY frame references a PRIORITY (0x2): As described in Appendix A.2.1, HTTP/3 does not
variety of identifiers. It is sent as the first frame on a provide a means of signaling priority.
request streams or on the control stream. See Section 7.2.3.
RST_STREAM (0x3): RST_STREAM frames do not exist, since QUIC RST_STREAM (0x3): RST_STREAM frames do not exist, since QUIC
provides stream lifecycle management. The same code point is used provides stream lifecycle management. The same code point is used
for the CANCEL_PUSH frame (Section 7.2.4). for the CANCEL_PUSH frame (Section 7.2.3).
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 7.2.5 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 7.2.6. 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 is sent only from server to client and does not
contain an error code. See Section 7.2.7. contain an error code. 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
type space in HTTP/3 is substantially larger (62 bits versus 8 bits), type space in HTTP/3 is substantially larger (62 bits versus 8 bits),
so many HTTP/3 frame types have no equivalent HTTP/2 code points. so many HTTP/3 frame types have no equivalent HTTP/2 code points.
See Section 11.3. See Section 11.3.
A.3. HTTP/2 SETTINGS Parameters A.3. HTTP/2 SETTINGS Parameters
An important difference from HTTP/2 is that settings are sent once, An important difference from HTTP/2 is that settings are sent once,
at the beginning of the connection, and thereafter cannot change. as the first frame of the control stream, and thereafter cannot
This eliminates many corner cases around synchronization of changes. change. This eliminates many corner cases around synchronization of
changes.
Some transport-level options that HTTP/2 specifies via the SETTINGS Some transport-level options that HTTP/2 specifies via the SETTINGS
frame are superseded by QUIC transport parameters in HTTP/3. The frame are superseded by QUIC transport parameters in HTTP/3. The
HTTP-level options that are retained in HTTP/3 have the same value as HTTP-level options that are retained in HTTP/3 have the same value as
in HTTP/2. in HTTP/2.
Below is a listing of how each HTTP/2 SETTINGS parameter is mapped: Below is a listing of how each HTTP/2 SETTINGS parameter is mapped:
SETTINGS_HEADER_TABLE_SIZE: See [QPACK]. SETTINGS_HEADER_TABLE_SIZE: See [QPACK].
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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 7.2.5.1. SETTINGS_MAX_HEADER_LIST_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 the format of their ported from HTTP/2 might choose to redefine the format of their
settings to avoid using the 62-bit encoding. settings to avoid using the 62-bit encoding.
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
IDs of settings defined in [HTTP2] have been reserved for simplicity. IDs of settings defined in [HTTP2] have been reserved for simplicity.
Note that the settings identifier space in HTTP/3 is substantially Note that the settings identifier space in HTTP/3 is substantially
larger (62 bits versus 16 bits), so many HTTP/3 settings have no larger (62 bits versus 16 bits), so many HTTP/3 settings have no
equivalent HTTP/2 code point. See Section 11.4. equivalent HTTP/2 code point. See Section 11.4.
As QUIC streams might arrive out-of-order, endpoints are advised to
not wait for the peers' settings to arrive before responding to other
streams. See Section 7.2.4.2.
A.4. HTTP/2 Error Codes A.4. HTTP/2 Error Codes
QUIC has the same concepts of "stream" and "connection" errors that QUIC has the same concepts of "stream" and "connection" errors that
HTTP/2 provides. However, there is no direct portability of HTTP/2 HTTP/2 provides. However, there is no direct portability of HTTP/2
error codes. error codes to HTTP/3 error codes; the values are shifted in order to
prevent accidental or implicit conversion.
The HTTP/2 error codes defined in Section 7 of [HTTP2] map to the The HTTP/2 error codes defined in Section 7 of [HTTP2] logically map
HTTP/3 error codes as follows: to the HTTP/3 error codes as follows:
NO_ERROR (0x0): HTTP_NO_ERROR in Section 8.1. NO_ERROR (0x0): HTTP_NO_ERROR in Section 8.1.
PROTOCOL_ERROR (0x1): This is mapped to HTTP_GENERAL_PROTOCOL_ERROR PROTOCOL_ERROR (0x1): This is mapped to HTTP_GENERAL_PROTOCOL_ERROR
except in cases where more specific error codes have been defined. except in cases where more specific error codes have been defined.
This includes HTTP_MALFORMED_FRAME, HTTP_WRONG_STREAM, This includes HTTP_FRAME_UNEXPECTED and
HTTP_UNEXPECTED_FRAME and HTTP_CLOSED_CRITICAL_STREAM defined in HTTP_CLOSED_CRITICAL_STREAM defined in Section 8.1.
Section 8.1.
INTERNAL_ERROR (0x2): HTTP_INTERNAL_ERROR in Section 8.1. INTERNAL_ERROR (0x2): HTTP_INTERNAL_ERROR in Section 8.1.
FLOW_CONTROL_ERROR (0x3): Not applicable, since QUIC handles flow FLOW_CONTROL_ERROR (0x3): Not applicable, since QUIC handles flow
control. Would provoke a QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA control.
from the QUIC layer.
SETTINGS_TIMEOUT (0x4): Not applicable, since no acknowledgement of SETTINGS_TIMEOUT (0x4): Not applicable, since no acknowledgement of
SETTINGS is defined. SETTINGS is defined.
STREAM_CLOSED (0x5): Not applicable, since QUIC handles stream STREAM_CLOSED (0x5): Not applicable, since QUIC handles stream
management. Would provoke a QUIC_STREAM_DATA_AFTER_TERMINATION management.
from the QUIC layer.
FRAME_SIZE_ERROR (0x6): HTTP_MALFORMED_FRAME error codes defined in FRAME_SIZE_ERROR (0x6): HTTP_FRAME_ERROR error code defined in
Section 8.1. Section 8.1.
REFUSED_STREAM (0x7): HTTP_REQUEST_REJECTED (in Section 8.1) is used REFUSED_STREAM (0x7): HTTP_REQUEST_REJECTED (in Section 8.1) is used
to indicate that a request was not processed. Otherwise, not to indicate that a request was not processed. Otherwise, not
applicable because QUIC handles stream management. A applicable because QUIC handles stream management.
STREAM_ID_ERROR at the QUIC layer is used for streams that are
improperly opened.
CANCEL (0x8): HTTP_REQUEST_CANCELLED in Section 8.1. CANCEL (0x8): HTTP_REQUEST_CANCELLED in Section 8.1.
COMPRESSION_ERROR (0x9): Multiple error codes are defined in COMPRESSION_ERROR (0x9): Multiple error codes are defined in
[QPACK]. [QPACK].
CONNECT_ERROR (0xa): HTTP_CONNECT_ERROR in Section 8.1. CONNECT_ERROR (0xa): HTTP_CONNECT_ERROR in Section 8.1.
ENHANCE_YOUR_CALM (0xb): HTTP_EXCESSIVE_LOAD in Section 8.1. ENHANCE_YOUR_CALM (0xb): HTTP_EXCESSIVE_LOAD in Section 8.1.
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HTTP_1_1_REQUIRED (0xd): HTTP_VERSION_FALLBACK in Section 8.1. HTTP_1_1_REQUIRED (0xd): HTTP_VERSION_FALLBACK in Section 8.1.
Error codes need to be defined for HTTP/2 and HTTP/3 separately. See Error codes need to be defined for HTTP/2 and HTTP/3 separately. See
Section 11.5. Section 11.5.
Appendix B. Change Log Appendix B. Change Log
*RFC Editor's Note:* Please remove this section prior to *RFC Editor's Note:* Please remove this section prior to
publication of a final version of this document. publication of a final version of this document.
B.1. Since draft-ietf-quic-http-21 B.1. Since draft-ietf-quic-http-22
o Removed priority signaling (#2922,#2924)
o Further changes to error codes (#2662,#2551):
* Error codes renumbered
* HTTP_MALFORMED_FRAME replaced by HTTP_FRAME_ERROR,
HTTP_ID_ERROR, and others
o Clarify how unknown frame types interact with required frame
sequence (#2867,#2858)
o Describe interactions with the transport in terms of defined
interface terms (#2857,#2805)
o Require the use of the "http-opportunistic" resource (RFC 8164)
when scheme is "http" (#2439,#2973)
o Settings identifiers cannot be duplicated (#2979)
o Changes to SETTINGS frames in 0-RTT (#2972,#2790,#2945):
* Servers must send all settings with non-default values in their
SETTINGS frame, even when resuming
* If a client doesn't have settings associated with a 0-RTT
ticket, it uses the defaults
* Servers can't accept early data if they cannot recover the
settings the client will have remembered
o Clarify that Upgrade and the 101 status code are prohibited
(#2898,#2889)
o Clarify that frame types reserved for greasing can occur on any
stream, but frame types reserved due to HTTP/2 correspondence are
prohibited (#2997,#2692,#2693)
o Unknown error codes cannot be treated as errors (#2998,#2816)
B.2. Since draft-ietf-quic-http-21
o No changes o No changes
B.2. Since draft-ietf-quic-http-20 B.3. Since draft-ietf-quic-http-20
o Prohibit closing the control stream (#2509, #2666) o Prohibit closing the control stream (#2509, #2666)
o Change default priority to use an orphan node (#2502, #2690) o Change default priority to use an orphan node (#2502, #2690)
o Exclusive priorities are restored (#2754, #2781) o Exclusive priorities are restored (#2754, #2781)
o Restrict use of frames when using CONNECT (#2229, #2702) o Restrict use of frames when using CONNECT (#2229, #2702)
o Close and maybe reset streams if a connection error occurs for o Close and maybe reset streams if a connection error occurs for
CONNECT (#2228, #2703) CONNECT (#2228, #2703)
o Encourage provision of sufficient unidirectional streams for QPACK o Encourage provision of sufficient unidirectional streams for QPACK
(#2100, #2529, #2762) (#2100, #2529, #2762)
o Allow extensions to use server-initiated bidirectional streams o Allow extensions to use server-initiated bidirectional streams
(#2711, #2773) (#2711, #2773)
o Clarify use of maximum header list size setting (#2516, #2774) o Clarify use of maximum header list size setting (#2516, #2774)
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o Encourage provision of sufficient unidirectional streams for QPACK o Encourage provision of sufficient unidirectional streams for QPACK
(#2100, #2529, #2762) (#2100, #2529, #2762)
o Allow extensions to use server-initiated bidirectional streams o Allow extensions to use server-initiated bidirectional streams
(#2711, #2773) (#2711, #2773)
o Clarify use of maximum header list size setting (#2516, #2774) o Clarify use of maximum header list size setting (#2516, #2774)
o Extensive changes to error codes and conditions of their sending o Extensive changes to error codes and conditions of their sending
* Require connection errors for more error conditions (#2511, * Require connection errors for more error conditions (#2511,
#2510) #2510)
* Updated the error codes for illegal GOAWAY frames (#2714, * Updated the error codes for illegal GOAWAY frames (#2714,
#2707) #2707)
* Specified error code for HEADERS on control stream (#2708) * Specified error code for HEADERS on control stream (#2708)
* Specified error code for servers receiving PUSH_PROMISE (#2709) * Specified error code for servers receiving PUSH_PROMISE (#2709)
* Specified error code for receiving DATA before HEADERS (#2715) * Specified error code for receiving DATA before HEADERS (#2715)
* Describe malformed messages and their handling (#2410, #2764) * Describe malformed messages and their handling (#2410, #2764)
* Remove HTTP_PUSH_ALREADY_IN_CACHE error (#2812, #2813) * Remove HTTP_PUSH_ALREADY_IN_CACHE error (#2812, #2813)
* Refactor Push ID related errors (#2818, #2820) * Refactor Push ID related errors (#2818, #2820)
* Rationalize HTTP/3 stream creation errors (#2821, #2822) * Rationalize HTTP/3 stream creation errors (#2821, #2822)
B.3. Since draft-ietf-quic-http-19 B.4. Since draft-ietf-quic-http-19
o SETTINGS_NUM_PLACEHOLDERS is 0x9 (#2443,#2530) o SETTINGS_NUM_PLACEHOLDERS is 0x9 (#2443,#2530)
o Non-zero bits in the Empty field of the PRIORITY frame MAY be o Non-zero bits in the Empty field of the PRIORITY frame MAY be
treated as an error (#2501) treated as an error (#2501)
B.4. Since draft-ietf-quic-http-18 B.5. Since draft-ietf-quic-http-18
o Resetting streams following a GOAWAY is recommended, but not o Resetting streams following a GOAWAY is recommended, but not
required (#2256,#2457) required (#2256,#2457)
o Use variable-length integers throughout (#2437,#2233,#2253,#2275) o Use variable-length integers throughout (#2437,#2233,#2253,#2275)
* Variable-length frame types, stream types, and settings * Variable-length frame types, stream types, and settings
identifiers identifiers
* Renumbered stream type assignments * Renumbered stream type assignments
* Modified associated reserved values * Modified associated reserved values
o Frame layout switched from Length-Type-Value to Type-Length-Value o Frame layout switched from Length-Type-Value to Type-Length-Value
(#2395,#2235) (#2395,#2235)
o Specified error code for servers receiving DUPLICATE_PUSH (#2497) o Specified error code for servers receiving DUPLICATE_PUSH (#2497)
o Use connection error for invalid PRIORITY (#2507, #2508) o Use connection error for invalid PRIORITY (#2507, #2508)
B.5. Since draft-ietf-quic-http-17 B.6. Since draft-ietf-quic-http-17
o HTTP_REQUEST_REJECTED is used to indicate a request can be retried o HTTP_REQUEST_REJECTED is used to indicate a request can be retried
(#2106, #2325) (#2106, #2325)
o Changed error code for GOAWAY on the wrong stream (#2231, #2343) o Changed error code for GOAWAY on the wrong stream (#2231, #2343)
B.6. Since draft-ietf-quic-http-16 B.7. Since draft-ietf-quic-http-16
o Rename "HTTP/QUIC" to "HTTP/3" (#1973) o Rename "HTTP/QUIC" to "HTTP/3" (#1973)
o Changes to PRIORITY frame (#1865, #2075) o Changes to PRIORITY frame (#1865, #2075)
* Permitted as first frame of request streams * Permitted as first frame of request streams
* Remove exclusive reprioritization * Remove exclusive reprioritization
* Changes to Prioritized Element Type bits * Changes to Prioritized Element Type bits
skipping to change at page 58, line 5 skipping to change at page 53, line 38
(#1809, #1846, #2038) (#1809, #1846, #2038)
o Clarify message processing rules for streams that aren't closed o Clarify message processing rules for streams that aren't closed
(#1972, #2003) (#1972, #2003)
o Removed reservation of error code 0 and moved HTTP_NO_ERROR to o Removed reservation of error code 0 and moved HTTP_NO_ERROR to
this value (#1922) this value (#1922)
o Removed prohibition of zero-length DATA frames (#2098) o Removed prohibition of zero-length DATA frames (#2098)
B.7. Since draft-ietf-quic-http-15 B.8. Since draft-ietf-quic-http-15
Substantial editorial reorganization; no technical changes. Substantial editorial reorganization; no technical changes.
B.8. Since draft-ietf-quic-http-14 B.9. Since draft-ietf-quic-http-14
o Recommend sensible values for QUIC transport parameters o Recommend sensible values for QUIC transport parameters
(#1720,#1806) (#1720,#1806)
o Define error for missing SETTINGS frame (#1697,#1808) o Define error for missing SETTINGS frame (#1697,#1808)
o Setting values are variable-length integers (#1556,#1807) and do o Setting values are variable-length integers (#1556,#1807) and do
not have separate maximum values (#1820) not have separate maximum values (#1820)
o Expanded discussion of connection closure (#1599,#1717,#1712) o Expanded discussion of connection closure (#1599,#1717,#1712)
skipping to change at page 58, line 20 skipping to change at page 54, line 4
o Recommend sensible values for QUIC transport parameters o Recommend sensible values for QUIC transport parameters
(#1720,#1806) (#1720,#1806)
o Define error for missing SETTINGS frame (#1697,#1808) o Define error for missing SETTINGS frame (#1697,#1808)
o Setting values are variable-length integers (#1556,#1807) and do o Setting values are variable-length integers (#1556,#1807) and do
not have separate maximum values (#1820) not have separate maximum values (#1820)
o Expanded discussion of connection closure (#1599,#1717,#1712) o Expanded discussion of connection closure (#1599,#1717,#1712)
o HTTP_VERSION_FALLBACK falls back to HTTP/1.1 (#1677,#1685) o HTTP_VERSION_FALLBACK falls back to HTTP/1.1 (#1677,#1685)
B.9. Since draft-ietf-quic-http-13 B.10. Since draft-ietf-quic-http-13
o Reserved some frame types for grease (#1333, #1446) o Reserved some frame types for grease (#1333, #1446)
o Unknown unidirectional stream types are tolerated, not errors; o Unknown unidirectional stream types are tolerated, not errors;
some reserved for grease (#1490, #1525) some reserved for grease (#1490, #1525)
o Require settings to be remembered for 0-RTT, prohibit reductions o Require settings to be remembered for 0-RTT, prohibit reductions
(#1541, #1641) (#1541, #1641)
o Specify behavior for truncated requests (#1596, #1643) o Specify behavior for truncated requests (#1596, #1643)
B.10. Since draft-ietf-quic-http-12 B.11. Since draft-ietf-quic-http-12
o TLS SNI extension isn't mandatory if an alternative method is used o TLS SNI extension isn't mandatory if an alternative method is used
(#1459, #1462, #1466) (#1459, #1462, #1466)
o Removed flags from HTTP/3 frames (#1388, #1398) o Removed flags from HTTP/3 frames (#1388, #1398)
o Reserved frame types and settings for use in preserving o Reserved frame types and settings for use in preserving
extensibility (#1333, #1446) extensibility (#1333, #1446)
o Added general error code (#1391, #1397) o Added general error code (#1391, #1397)
o Unidirectional streams carry a type byte and are extensible o Unidirectional streams carry a type byte and are extensible
(#910,#1359) (#910,#1359)
o Priority mechanism now uses explicit placeholders to enable o Priority mechanism now uses explicit placeholders to enable
persistent structure in the tree (#441,#1421,#1422) persistent structure in the tree (#441,#1421,#1422)
B.11. Since draft-ietf-quic-http-11 B.12. Since draft-ietf-quic-http-11
o Moved QPACK table updates and acknowledgments to dedicated streams o Moved QPACK table updates and acknowledgments to dedicated streams
(#1121, #1122, #1238) (#1121, #1122, #1238)
B.12. Since draft-ietf-quic-http-10 B.13. Since draft-ietf-quic-http-10
o Settings need to be remembered when attempting and accepting 0-RTT o Settings need to be remembered when attempting and accepting 0-RTT
(#1157, #1207) (#1157, #1207)
B.13. Since draft-ietf-quic-http-09 B.14. Since draft-ietf-quic-http-09
o Selected QCRAM for header compression (#228, #1117) o Selected QCRAM for header compression (#228, #1117)
o The server_name TLS extension is now mandatory (#296, #495) o The server_name TLS extension is now mandatory (#296, #495)
o Specified handling of unsupported versions in Alt-Svc (#1093, o Specified handling of unsupported versions in Alt-Svc (#1093,
#1097) #1097)
B.14. Since draft-ietf-quic-http-08 B.15. Since draft-ietf-quic-http-08
o Clarified connection coalescing rules (#940, #1024) o Clarified connection coalescing rules (#940, #1024)
B.15. Since draft-ietf-quic-http-07 B.16. Since draft-ietf-quic-http-07
o Changes for integer encodings in QUIC (#595,#905) o Changes for integer encodings in QUIC (#595,#905)
o Use unidirectional streams as appropriate (#515, #240, #281, #886) o Use unidirectional streams as appropriate (#515, #240, #281, #886)
o Improvement to the description of GOAWAY (#604, #898) o Improvement to the description of GOAWAY (#604, #898)
o Improve description of server push usage (#947, #950, #957) o Improve description of server push usage (#947, #950, #957)
B.16. Since draft-ietf-quic-http-06 B.17. Since draft-ietf-quic-http-06
o Track changes in QUIC error code usage (#485) o Track changes in QUIC error code usage (#485)
B.17. Since draft-ietf-quic-http-05 B.18. Since draft-ietf-quic-http-05
o Made push ID sequential, add MAX_PUSH_ID, remove o Made push ID sequential, add MAX_PUSH_ID, remove
SETTINGS_ENABLE_PUSH (#709) SETTINGS_ENABLE_PUSH (#709)
o Guidance about keep-alive and QUIC PINGs (#729) o Guidance about keep-alive and QUIC PINGs (#729)
o Expanded text on GOAWAY and cancellation (#757) o Expanded text on GOAWAY and cancellation (#757)
B.18. Since draft-ietf-quic-http-04 B.19. Since draft-ietf-quic-http-04
o Cite RFC 5234 (#404) o Cite RFC 5234 (#404)
o Return to a single stream per request (#245,#557) o Return to a single stream per request (#245,#557)
o Use separate frame type and settings registries from HTTP/2 (#81) o Use separate frame type and settings registries from HTTP/2 (#81)
o SETTINGS_ENABLE_PUSH instead of SETTINGS_DISABLE_PUSH (#477) o SETTINGS_ENABLE_PUSH instead of SETTINGS_DISABLE_PUSH (#477)
o Restored GOAWAY (#696) o Restored GOAWAY (#696)
o Identify server push using Push ID rather than a stream ID o Identify server push using Push ID rather than a stream ID
(#702,#281) (#702,#281)
o DATA frames cannot be empty (#700) o DATA frames cannot be empty (#700)
B.19. Since draft-ietf-quic-http-03 B.20. Since draft-ietf-quic-http-03
None. None.
B.20. Since draft-ietf-quic-http-02 B.21. Since draft-ietf-quic-http-02
o Track changes in transport draft o Track changes in transport draft
B.21. Since draft-ietf-quic-http-01 B.22. Since draft-ietf-quic-http-01
o SETTINGS changes (#181): o SETTINGS changes (#181):
* SETTINGS can be sent only once at the start of a connection; no * SETTINGS can be sent only once at the start of a connection; no
changes thereafter changes thereafter
* SETTINGS_ACK removed * SETTINGS_ACK removed
* Settings can only occur in the SETTINGS frame a single time * Settings can only occur in the SETTINGS frame a single time
skipping to change at page 61, line 4 skipping to change at page 56, line 35
o Alt-Svc parameter changed from "v" to "quic"; format updated o Alt-Svc parameter changed from "v" to "quic"; format updated
(#229) (#229)
o Closing the connection control stream or any message control o Closing the connection control stream or any message control
stream is a fatal error (#176) stream is a fatal error (#176)
o HPACK Sequence counter can wrap (#173) o HPACK Sequence counter can wrap (#173)
o 0-RTT guidance added o 0-RTT guidance added
o Guide to differences from HTTP/2 and porting HTTP/2 extensions o Guide to differences from HTTP/2 and porting HTTP/2 extensions
added (#127,#242) added (#127,#242)
B.22. Since draft-ietf-quic-http-00 B.23. Since draft-ietf-quic-http-00
o Changed "HTTP/2-over-QUIC" to "HTTP/QUIC" throughout (#11,#29) o Changed "HTTP/2-over-QUIC" to "HTTP/QUIC" throughout (#11,#29)
o Changed from using HTTP/2 framing within Stream 3 to new framing o Changed from using HTTP/2 framing within Stream 3 to new framing
format and two-stream-per-request model (#71,#72,#73) format and two-stream-per-request model (#71,#72,#73)
o Adopted SETTINGS format from draft-bishop-httpbis-extended- o Adopted SETTINGS format from draft-bishop-httpbis-extended-
settings-01 settings-01
o Reworked SETTINGS_ACK to account for indeterminate inter-stream o Reworked SETTINGS_ACK to account for indeterminate inter-stream
skipping to change at page 61, line 21 skipping to change at page 57, line 4
o Changed from using HTTP/2 framing within Stream 3 to new framing o Changed from using HTTP/2 framing within Stream 3 to new framing
format and two-stream-per-request model (#71,#72,#73) format and two-stream-per-request model (#71,#72,#73)
o Adopted SETTINGS format from draft-bishop-httpbis-extended- o Adopted SETTINGS format from draft-bishop-httpbis-extended-
settings-01 settings-01
o Reworked SETTINGS_ACK to account for indeterminate inter-stream o Reworked SETTINGS_ACK to account for indeterminate inter-stream
order (#75) order (#75)
o Described CONNECT pseudo-method (#95) o Described CONNECT pseudo-method (#95)
o Updated ALPN token and Alt-Svc guidance (#13,#87) o Updated ALPN token and Alt-Svc guidance (#13,#87)
o Application-layer-defined error codes (#19,#74) o Application-layer-defined error codes (#19,#74)
B.23. Since draft-shade-quic-http2-mapping-00 B.24. Since draft-shade-quic-http2-mapping-00
o Adopted as base for draft-ietf-quic-http o Adopted as base for draft-ietf-quic-http
o Updated authors/editors list o Updated authors/editors list
Acknowledgements Acknowledgements
The original authors of this specification were Robbie Shade and Mike The original authors of this specification were Robbie Shade and Mike
Warres. Warres.
 End of changes. 202 change blocks. 
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