rfc9114.original   rfc9114.txt 
QUIC M. Bishop, Ed. Internet Engineering Task Force (IETF) M. Bishop, Ed.
Internet-Draft Akamai Request for Comments: 9114 Akamai
Intended status: Standards Track 2 February 2021 Category: Standards Track June 2022
Expires: 6 August 2021 ISSN: 2070-1721
Hypertext Transfer Protocol Version 3 (HTTP/3) HTTP/3
draft-ietf-quic-http-34
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.
DO NOT DEPLOY THIS VERSION OF HTTP
DO NOT DEPLOY THIS VERSION OF HTTP/3 UNTIL IT IS IN AN RFC. This
version is still a work in progress. For trial deployments, please
use earlier versions.
Note to Readers
Discussion of this draft takes place on the QUIC working group
mailing list (quic@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/search/?email_list=quic.
Working Group information can be found at https://github.com/quicwg;
source code and issues list for this draft can be found at
https://github.com/quicwg/base-drafts/labels/-http.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This document is a product of the Internet Engineering Task Force
Task Force (IETF). Note that other groups may also distribute (IETF). It represents the consensus of the IETF community. It has
working documents as Internet-Drafts. The list of current Internet- received public review and has been approved for publication by the
Drafts is at https://datatracker.ietf.org/drafts/current/. Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Internet-Drafts are draft documents valid for a maximum of six months Information about the current status of this document, any errata,
and may be updated, replaced, or obsoleted by other documents at any and how to provide feedback on it may be obtained at
time. It is inappropriate to use Internet-Drafts as reference https://www.rfc-editor.org/info/rfc9114.
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 6 August 2021.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2022 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
1.1. Prior versions of HTTP . . . . . . . . . . . . . . . . . 5 1.1. Prior Versions of HTTP
1.2. Delegation to QUIC . . . . . . . . . . . . . . . . . . . 5 1.2. Delegation to QUIC
2. HTTP/3 Protocol Overview . . . . . . . . . . . . . . . . . . 5 2. HTTP/3 Protocol Overview
2.1. Document Organization . . . . . . . . . . . . . . . . . . 6 2.1. Document Organization
2.2. Conventions and Terminology . . . . . . . . . . . . . . . 7 2.2. Conventions and Terminology
3. Connection Setup and Management . . . . . . . . . . . . . . . 8 3. Connection Setup and Management
3.1. Discovering an HTTP/3 Endpoint . . . . . . . . . . . . . 8 3.1. Discovering an HTTP/3 Endpoint
3.1.1. HTTP Alternative Services . . . . . . . . . . . . . . 9 3.1.1. HTTP Alternative Services
3.1.2. Other Schemes . . . . . . . . . . . . . . . . . . . . 10 3.1.2. Other Schemes
3.2. Connection Establishment . . . . . . . . . . . . . . . . 10 3.2. Connection Establishment
3.3. Connection Reuse . . . . . . . . . . . . . . . . . . . . 11 3.3. Connection Reuse
4. HTTP Request Lifecycle . . . . . . . . . . . . . . . . . . . 12 4. Expressing HTTP Semantics in HTTP/3
4.1. HTTP Message Exchanges . . . . . . . . . . . . . . . . . 12 4.1. HTTP Message Framing
4.1.1. Field Formatting and Compression . . . . . . . . . . 14 4.1.1. Request Cancellation and Rejection
4.1.2. Request Cancellation and Rejection . . . . . . . . . 17 4.1.2. Malformed Requests and Responses
4.1.3. Malformed Requests and Responses . . . . . . . . . . 18 4.2. HTTP Fields
4.2. The CONNECT Method . . . . . . . . . . . . . . . . . . . 19 4.2.1. Field Compression
4.3. HTTP Upgrade . . . . . . . . . . . . . . . . . . . . . . 21 4.2.2. Header Size Constraints
4.4. Server Push . . . . . . . . . . . . . . . . . . . . . . . 21 4.3. HTTP Control Data
5. Connection Closure . . . . . . . . . . . . . . . . . . . . . 23 4.3.1. Request Pseudo-Header Fields
5.1. Idle Connections . . . . . . . . . . . . . . . . . . . . 23 4.3.2. Response Pseudo-Header Fields
5.2. Connection Shutdown . . . . . . . . . . . . . . . . . . . 24 4.4. The CONNECT Method
5.3. Immediate Application Closure . . . . . . . . . . . . . . 26 4.5. HTTP Upgrade
5.4. Transport Closure . . . . . . . . . . . . . . . . . . . . 26 4.6. Server Push
6. Stream Mapping and Usage . . . . . . . . . . . . . . . . . . 27 5. Connection Closure
6.1. Bidirectional Streams . . . . . . . . . . . . . . . . . . 27 5.1. Idle Connections
6.2. Unidirectional Streams . . . . . . . . . . . . . . . . . 28 5.2. Connection Shutdown
6.2.1. Control Streams . . . . . . . . . . . . . . . . . . . 29 5.3. Immediate Application Closure
6.2.2. Push Streams . . . . . . . . . . . . . . . . . . . . 30 5.4. Transport Closure
6.2.3. Reserved Stream Types . . . . . . . . . . . . . . . . 30 6. Stream Mapping and Usage
7. HTTP Framing Layer . . . . . . . . . . . . . . . . . . . . . 31 6.1. Bidirectional Streams
7.1. Frame Layout . . . . . . . . . . . . . . . . . . . . . . 32 6.2. Unidirectional Streams
7.2. Frame Definitions . . . . . . . . . . . . . . . . . . . . 32 6.2.1. Control Streams
7.2.1. DATA . . . . . . . . . . . . . . . . . . . . . . . . 32 6.2.2. Push Streams
7.2.2. HEADERS . . . . . . . . . . . . . . . . . . . . . . . 33 6.2.3. Reserved Stream Types
7.2.3. CANCEL_PUSH . . . . . . . . . . . . . . . . . . . . . 33 7. HTTP Framing Layer
7.2.4. SETTINGS . . . . . . . . . . . . . . . . . . . . . . 35 7.1. Frame Layout
7.2.5. PUSH_PROMISE . . . . . . . . . . . . . . . . . . . . 38 7.2. Frame Definitions
7.2.6. GOAWAY . . . . . . . . . . . . . . . . . . . . . . . 39 7.2.1. DATA
7.2.7. MAX_PUSH_ID . . . . . . . . . . . . . . . . . . . . . 40 7.2.2. HEADERS
7.2.8. Reserved Frame Types . . . . . . . . . . . . . . . . 41 7.2.3. CANCEL_PUSH
8. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 41 7.2.4. SETTINGS
8.1. HTTP/3 Error Codes . . . . . . . . . . . . . . . . . . . 42 7.2.5. PUSH_PROMISE
9. Extensions to HTTP/3 . . . . . . . . . . . . . . . . . . . . 43 7.2.6. GOAWAY
10. Security Considerations . . . . . . . . . . . . . . . . . . . 44 7.2.7. MAX_PUSH_ID
10.1. Server Authority . . . . . . . . . . . . . . . . . . . . 44 7.2.8. Reserved Frame Types
10.2. Cross-Protocol Attacks . . . . . . . . . . . . . . . . . 44 8. Error Handling
10.3. Intermediary Encapsulation Attacks . . . . . . . . . . . 45 8.1. HTTP/3 Error Codes
10.4. Cacheability of Pushed Responses . . . . . . . . . . . . 45 9. Extensions to HTTP/3
10.5. Denial-of-Service Considerations . . . . . . . . . . . . 45 10. Security Considerations
10.5.1. Limits on Field Section Size . . . . . . . . . . . . 46 10.1. Server Authority
10.5.2. CONNECT Issues . . . . . . . . . . . . . . . . . . . 47 10.2. Cross-Protocol Attacks
10.6. Use of Compression . . . . . . . . . . . . . . . . . . . 47 10.3. Intermediary-Encapsulation Attacks
10.7. Padding and Traffic Analysis . . . . . . . . . . . . . . 48 10.4. Cacheability of Pushed Responses
10.8. Frame Parsing . . . . . . . . . . . . . . . . . . . . . 48 10.5. Denial-of-Service Considerations
10.9. Early Data . . . . . . . . . . . . . . . . . . . . . . . 49 10.5.1. Limits on Field Section Size
10.10. Migration . . . . . . . . . . . . . . . . . . . . . . . 49 10.5.2. CONNECT Issues
10.11. Privacy Considerations . . . . . . . . . . . . . . . . . 49 10.6. Use of Compression
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 49 10.7. Padding and Traffic Analysis
11.1. Registration of HTTP/3 Identification String . . . . . . 50 10.8. Frame Parsing
11.2. New Registries . . . . . . . . . . . . . . . . . . . . . 50 10.9. Early Data
11.2.1. Frame Types . . . . . . . . . . . . . . . . . . . . 50 10.10. Migration
11.2.2. Settings Parameters . . . . . . . . . . . . . . . . 52 10.11. Privacy Considerations
11.2.3. Error Codes . . . . . . . . . . . . . . . . . . . . 53 11. IANA Considerations
11.2.4. Stream Types . . . . . . . . . . . . . . . . . . . . 55 11.1. Registration of HTTP/3 Identification String
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 56 11.2. New Registries
12.1. Normative References . . . . . . . . . . . . . . . . . . 56 11.2.1. Frame Types
12.2. Informative References . . . . . . . . . . . . . . . . . 57 11.2.2. Settings Parameters
Appendix A. Considerations for Transitioning from HTTP/2 . . . . 58 11.2.3. Error Codes
A.1. Streams . . . . . . . . . . . . . . . . . . . . . . . . . 59 11.2.4. Stream Types
A.2. HTTP Frame Types . . . . . . . . . . . . . . . . . . . . 60 12. References
A.2.1. Prioritization Differences . . . . . . . . . . . . . 60 12.1. Normative References
A.2.2. Field Compression Differences . . . . . . . . . . . . 60 12.2. Informative References
A.2.3. Flow Control Differences . . . . . . . . . . . . . . 61 Appendix A. Considerations for Transitioning from HTTP/2
A.2.4. Guidance for New Frame Type Definitions . . . . . . . 61 A.1. Streams
A.2.5. Comparison Between HTTP/2 and HTTP/3 Frame Types . . 61 A.2. HTTP Frame Types
A.3. HTTP/2 SETTINGS Parameters . . . . . . . . . . . . . . . 62 A.2.1. Prioritization Differences
A.4. HTTP/2 Error Codes . . . . . . . . . . . . . . . . . . . 64 A.2.2. Field Compression Differences
A.4.1. Mapping Between HTTP/2 and HTTP/3 Errors . . . . . . 65 A.2.3. Flow-Control Differences
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 65 A.2.4. Guidance for New Frame Type Definitions
B.1. Since draft-ietf-quic-http-32 . . . . . . . . . . . . . . 65 A.2.5. Comparison of HTTP/2 and HTTP/3 Frame Types
B.2. Since draft-ietf-quic-http-31 . . . . . . . . . . . . . . 66 A.3. HTTP/2 SETTINGS Parameters
B.3. Since draft-ietf-quic-http-30 . . . . . . . . . . . . . . 66 A.4. HTTP/2 Error Codes
B.4. Since draft-ietf-quic-http-29 . . . . . . . . . . . . . . 66 A.4.1. Mapping between HTTP/2 and HTTP/3 Errors
B.5. Since draft-ietf-quic-http-28 . . . . . . . . . . . . . . 66 Acknowledgments
B.6. Since draft-ietf-quic-http-27 . . . . . . . . . . . . . . 66 Index
B.7. Since draft-ietf-quic-http-26 . . . . . . . . . . . . . . 66 Author's Address
B.8. Since draft-ietf-quic-http-25 . . . . . . . . . . . . . . 66
B.9. Since draft-ietf-quic-http-24 . . . . . . . . . . . . . . 67
B.10. Since draft-ietf-quic-http-23 . . . . . . . . . . . . . . 67
B.11. Since draft-ietf-quic-http-22 . . . . . . . . . . . . . . 67
B.12. Since draft-ietf-quic-http-21 . . . . . . . . . . . . . . 68
B.13. Since draft-ietf-quic-http-20 . . . . . . . . . . . . . . 68
B.14. Since draft-ietf-quic-http-19 . . . . . . . . . . . . . . 69
B.15. Since draft-ietf-quic-http-18 . . . . . . . . . . . . . . 69
B.16. Since draft-ietf-quic-http-17 . . . . . . . . . . . . . . 69
B.17. Since draft-ietf-quic-http-16 . . . . . . . . . . . . . . 70
B.18. Since draft-ietf-quic-http-15 . . . . . . . . . . . . . . 70
B.19. Since draft-ietf-quic-http-14 . . . . . . . . . . . . . . 70
B.20. Since draft-ietf-quic-http-13 . . . . . . . . . . . . . . 70
B.21. Since draft-ietf-quic-http-12 . . . . . . . . . . . . . . 71
B.22. Since draft-ietf-quic-http-11 . . . . . . . . . . . . . . 71
B.23. Since draft-ietf-quic-http-10 . . . . . . . . . . . . . . 71
B.24. Since draft-ietf-quic-http-09 . . . . . . . . . . . . . . 71
B.25. Since draft-ietf-quic-http-08 . . . . . . . . . . . . . . 72
B.26. Since draft-ietf-quic-http-07 . . . . . . . . . . . . . . 72
B.27. Since draft-ietf-quic-http-06 . . . . . . . . . . . . . . 72
B.28. Since draft-ietf-quic-http-05 . . . . . . . . . . . . . . 72
B.29. Since draft-ietf-quic-http-04 . . . . . . . . . . . . . . 72
B.30. Since draft-ietf-quic-http-03 . . . . . . . . . . . . . . 72
B.31. Since draft-ietf-quic-http-02 . . . . . . . . . . . . . . 73
B.32. Since draft-ietf-quic-http-01 . . . . . . . . . . . . . . 73
B.33. Since draft-ietf-quic-http-00 . . . . . . . . . . . . . . 73
B.34. Since draft-shade-quic-http2-mapping-00 . . . . . . . . . 74
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 74
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 75
1. Introduction 1. Introduction
HTTP semantics ([SEMANTICS]) are used for a broad range of services HTTP semantics ([HTTP]) are used for a broad range of services on the
on the Internet. These semantics have most commonly been used with Internet. These semantics have most commonly been used with HTTP/1.1
HTTP/1.1 and HTTP/2. HTTP/1.1 has been used over a variety of and HTTP/2. HTTP/1.1 has been used over a variety of transport and
transport and session layers, while HTTP/2 has been used primarily session layers, while HTTP/2 has been used primarily with TLS over
with TLS over TCP. HTTP/3 supports the same semantics over a new TCP. HTTP/3 supports the same semantics over a new transport
transport protocol, QUIC. protocol: QUIC.
1.1. Prior versions of HTTP 1.1. Prior Versions of HTTP
HTTP/1.1 ([HTTP11]) uses whitespace-delimited text fields to convey HTTP/1.1 ([HTTP/1.1]) uses whitespace-delimited text fields to convey
HTTP messages. While these exchanges are human-readable, using HTTP messages. While these exchanges are human readable, using
whitespace for message formatting leads to parsing complexity and whitespace for message formatting leads to parsing complexity and
excessive tolerance of variant behavior. excessive tolerance of variant behavior.
Because HTTP/1.1 does not include a multiplexing layer, multiple TCP Because HTTP/1.1 does not include a multiplexing layer, multiple TCP
connections are often used to service requests in parallel. However, connections are often used to service requests in parallel. However,
that has a negative impact on congestion control and network that has a negative impact on congestion control and network
efficiency, since TCP does not share congestion control across efficiency, since TCP does not share congestion control across
multiple connections. multiple connections.
HTTP/2 ([HTTP2]) introduced a binary framing and multiplexing layer HTTP/2 ([HTTP/2]) introduced a binary framing and multiplexing layer
to improve latency without modifying the transport layer. However, to improve latency without modifying the transport layer. However,
because the parallel nature of HTTP/2's multiplexing is not visible because the parallel nature of HTTP/2's multiplexing is not visible
to TCP's loss recovery mechanisms, a lost or reordered packet causes to TCP's loss recovery mechanisms, a lost or reordered packet causes
all active transactions to experience a stall regardless of whether all active transactions to experience a stall regardless of whether
that transaction was directly impacted by the lost packet. that transaction was directly impacted by the lost packet.
1.2. Delegation to QUIC 1.2. Delegation to QUIC
The QUIC transport protocol incorporates stream multiplexing and per- The QUIC transport protocol incorporates stream multiplexing and per-
stream flow control, similar to that provided by the HTTP/2 framing stream flow control, similar to that provided by the HTTP/2 framing
layer. By providing reliability at the stream level and congestion layer. By providing reliability at the stream level and congestion
control across the entire connection, QUIC has the capability to control across the entire connection, QUIC has the capability to
improve the performance of HTTP compared to a TCP mapping. QUIC also improve the performance of HTTP compared to a TCP mapping. QUIC also
incorporates TLS 1.3 ([TLS13]) at the transport layer, offering incorporates TLS 1.3 ([TLS]) at the transport layer, offering
comparable confidentiality and integrity to running TLS over TCP, comparable confidentiality and integrity to running TLS over TCP,
with the improved connection setup latency of TCP Fast Open ([TFO]). with the improved connection setup latency of TCP Fast Open ([TFO]).
This document defines HTTP/3, a mapping of HTTP semantics over the This document defines HTTP/3: a mapping of HTTP semantics over the
QUIC transport protocol, drawing heavily on the design of HTTP/2. QUIC transport protocol, drawing heavily on the design of HTTP/2.
HTTP/3 relies on QUIC to provide confidentiality and integrity HTTP/3 relies on QUIC to provide confidentiality and integrity
protection of data; peer authentication; and reliable, in-order, per- protection of data; peer authentication; and reliable, in-order, per-
stream delivery. While delegating stream lifetime and flow control stream delivery. While delegating stream lifetime and flow-control
issues to QUIC, a binary framing similar to the HTTP/2 framing is issues to QUIC, a binary framing similar to the HTTP/2 framing is
used on each stream. Some HTTP/2 features are subsumed by QUIC, used on each stream. Some HTTP/2 features are subsumed by QUIC,
while other features are implemented atop 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 [HTTP/2].
2. HTTP/3 Protocol Overview 2. HTTP/3 Protocol Overview
HTTP/3 provides a transport for HTTP semantics using the QUIC HTTP/3 provides a transport for HTTP semantics using the QUIC
transport protocol and an internal framing layer similar to HTTP/2. transport protocol and an internal framing layer similar to HTTP/2.
Once a client knows that an HTTP/3 server exists at a certain Once a client knows that an HTTP/3 server exists at a certain
endpoint, it opens a QUIC connection. QUIC provides protocol endpoint, it opens a QUIC connection. QUIC provides protocol
negotiation, stream-based multiplexing, and flow control. Discovery negotiation, stream-based multiplexing, and flow control. Discovery
of an HTTP/3 endpoint is described in Section 3.1. of an HTTP/3 endpoint is described in Section 3.1.
Within each stream, the basic unit of HTTP/3 communication is a frame Within each stream, the basic unit of HTTP/3 communication is a frame
(Section 7.2). Each frame type serves a different purpose. For (Section 7.2). Each frame type serves a different purpose. For
example, HEADERS and DATA frames form the basis of HTTP requests and example, HEADERS and DATA frames form the basis of HTTP requests and
responses (Section 4.1). Frames that apply to the entire connection responses (Section 4.1). Frames that apply to the entire connection
are conveyed on a dedicated control stream. are conveyed on a dedicated control stream.
Multiplexing of requests is performed using the QUIC stream Multiplexing of requests is performed using the QUIC stream
abstraction, described in Section 2 of [QUIC-TRANSPORT]. Each abstraction, which is described in Section 2 of [QUIC-TRANSPORT].
request-response pair consumes a single QUIC stream. Streams are Each request-response pair consumes a single QUIC stream. Streams
independent of each other, so one stream that is blocked or suffers are independent of each other, so one stream that is blocked or
packet loss does not prevent progress on other streams. suffers packet loss does not prevent progress on other streams.
Server push is an interaction mode introduced in HTTP/2 ([HTTP2]) Server push is an interaction mode introduced in HTTP/2 ([HTTP/2])
that permits a server to push a request-response exchange to a client that permits a server to push a request-response exchange to a client
in anticipation of the client making the indicated request. This in anticipation of the client making the indicated request. This
trades off network usage against a potential latency gain. Several trades off network usage against a potential latency gain. Several
HTTP/3 frames are used to manage server push, such as PUSH_PROMISE, HTTP/3 frames are used to manage server push, such as PUSH_PROMISE,
MAX_PUSH_ID, and CANCEL_PUSH. MAX_PUSH_ID, and CANCEL_PUSH.
As in HTTP/2, request and response fields are compressed for As in HTTP/2, request and response fields are compressed for
transmission. Because HPACK ([HPACK]) relies on in-order transmission. Because HPACK ([HPACK]) relies on in-order
transmission of compressed field sections (a guarantee not provided transmission of compressed field sections (a guarantee not provided
by QUIC), HTTP/3 replaces HPACK with QPACK ([QPACK]). QPACK uses by QUIC), HTTP/3 replaces HPACK with QPACK ([QPACK]). QPACK uses
separate unidirectional streams to modify and track field table separate unidirectional streams to modify and track field table
state, while encoded field sections refer to the state of the table state, while encoded field sections refer to the state of the table
without modifying it. without modifying it.
2.1. Document Organization 2.1. Document Organization
The following sections provide a detailed overview of the lifecycle The following sections provide a detailed overview of the lifecycle
of an HTTP/3 connection: of an HTTP/3 connection:
* Connection Setup and Management (Section 3) covers how an HTTP/3 * "Connection Setup and Management" (Section 3) covers how an HTTP/3
endpoint is discovered and an HTTP/3 connection is established. endpoint is discovered and an HTTP/3 connection is established.
* HTTP Request Lifecycle (Section 4) describes how HTTP semantics * "Expressing HTTP Semantics in HTTP/3" (Section 4) describes how
are expressed using frames. HTTP semantics are expressed using frames.
* Connection Closure (Section 5) describes how HTTP/3 connections * "Connection Closure" (Section 5) describes how HTTP/3 connections
are terminated, either gracefully or abruptly. are terminated, either gracefully or abruptly.
The details of the wire protocol and interactions with the transport The details of the wire protocol and interactions with the transport
are described in subsequent sections: are described in subsequent sections:
* Stream Mapping and Usage (Section 6) describes the way QUIC * "Stream Mapping and Usage" (Section 6) describes the way QUIC
streams are used. streams are used.
* HTTP Framing Layer (Section 7) describes the frames used on most * "HTTP Framing Layer" (Section 7) describes the frames used on most
streams. streams.
* Error Handling (Section 8) describes how error conditions are * "Error Handling" (Section 8) describes how error conditions are
handled and expressed, either on a particular stream or for the handled and expressed, either on a particular stream or for the
connection as a whole. connection as a whole.
Additional resources are provided in the final sections: Additional resources are provided in the final sections:
* Extensions to HTTP/3 (Section 9) describes how new capabilities * "Extensions to HTTP/3" (Section 9) describes how new capabilities
can be added in future documents. can be added in future documents.
* A more detailed comparison between HTTP/2 and HTTP/3 can be found * A more detailed comparison between HTTP/2 and HTTP/3 can be found
in Appendix A. in Appendix A.
2.2. Conventions and Terminology 2.2. Conventions and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
skipping to change at page 7, line 42 skipping to change at line 281
[QUIC-TRANSPORT]. [QUIC-TRANSPORT].
The following terms are used: The following terms are used:
abort: An abrupt termination of a connection or stream, possibly due abort: An abrupt termination of a connection or stream, possibly due
to an error condition. to an error condition.
client: The endpoint that initiates an HTTP/3 connection. Clients client: The endpoint that initiates an HTTP/3 connection. Clients
send HTTP requests and receive HTTP responses. send HTTP requests and receive HTTP responses.
connection: A transport-layer connection between two endpoints, connection: A transport-layer connection between two endpoints using
using QUIC as the transport protocol. QUIC as the transport protocol.
connection error: An error that affects the entire HTTP/3 connection error: An error that affects the entire HTTP/3
connection. connection.
endpoint: Either the client or server of the connection. endpoint: Either the client or server of the connection.
frame: The smallest unit of communication on a stream in HTTP/3, frame: The smallest unit of communication on a stream in HTTP/3,
consisting of a header and a variable-length sequence of bytes consisting of a header and a variable-length sequence of bytes
structured according to the frame type. structured according to the frame type.
Protocol elements called "frames" exist in both this document and Protocol elements called "frames" exist in both this document and
[QUIC-TRANSPORT]. Where frames from [QUIC-TRANSPORT] are [QUIC-TRANSPORT]. Where frames from [QUIC-TRANSPORT] are
referenced, the frame name will be prefaced with "QUIC." For referenced, the frame name will be prefaced with "QUIC". For
example, "QUIC CONNECTION_CLOSE frames." References without this example, "QUIC CONNECTION_CLOSE frames". References without this
preface refer to frames defined in Section 7.2. preface refer to frames defined in Section 7.2.
HTTP/3 connection: A QUIC connection where the negotiated HTTP/3 connection: A QUIC connection where the negotiated
application protocol is HTTP/3. application protocol is HTTP/3.
peer: An endpoint. When discussing a particular endpoint, "peer" peer: An endpoint. When discussing a particular endpoint, "peer"
refers to the endpoint that is remote to the primary subject of refers to the endpoint that is remote to the primary subject of
discussion. discussion.
receiver: An endpoint that is receiving frames. receiver: An endpoint that is receiving frames.
sender: An endpoint that is transmitting frames. sender: An endpoint that is transmitting frames.
server: The endpoint that accepts an HTTP/3 connection. Servers server: The endpoint that accepts an HTTP/3 connection. Servers
receive HTTP requests and send HTTP responses. receive HTTP requests and send HTTP responses.
stream: A bidirectional or unidirectional bytestream provided by the stream: A bidirectional or unidirectional bytestream provided by the
QUIC transport. All streams within an HTTP/3 connection can be QUIC transport. All streams within an HTTP/3 connection can be
considered "HTTP/3 streams," but multiple stream types are defined considered "HTTP/3 streams", but multiple stream types are defined
within HTTP/3. within HTTP/3.
stream error: An application-level error on the individual stream. stream error: An application-level error on the individual stream.
The term "content" is defined in Section 6.4 of [SEMANTICS]. The term "content" is defined in Section 6.4 of [HTTP].
Finally, the terms "resource", "message", "user agent", "origin Finally, the terms "resource", "message", "user agent", "origin
server", "gateway", "intermediary", "proxy", and "tunnel" are defined server", "gateway", "intermediary", "proxy", and "tunnel" are defined
in Section 3 of [SEMANTICS]. in Section 3 of [HTTP].
Packet diagrams in this document use the format defined in Packet diagrams in this document use the format defined in
Section 1.3 of [QUIC-TRANSPORT] to illustrate the order and size of Section 1.3 of [QUIC-TRANSPORT] to illustrate the order and size of
fields. fields.
3. Connection Setup and Management 3. Connection Setup and Management
3.1. Discovering an HTTP/3 Endpoint 3.1. Discovering an HTTP/3 Endpoint
HTTP relies on the notion of an authoritative response: a response HTTP relies on the notion of an authoritative response: a response
that has been determined to be the most appropriate response for that that has been determined to be the most appropriate response for that
request given the state of the target resource at the time of request given the state of the target resource at the time of
response message origination by (or at the direction of) the origin response message origination by (or at the direction of) the origin
server identified within the target URI. Locating an authoritative server identified within the target URI. Locating an authoritative
server for an HTTP URI is discussed in Section 4.3 of [SEMANTICS]. server for an HTTP URI is discussed in Section 4.3 of [HTTP].
The "https" scheme associates authority with possession of a The "https" scheme associates authority with possession of a
certificate that the client considers to be trustworthy for the host certificate that the client considers to be trustworthy for the host
identified by the authority component of the URI. Upon receiving a identified by the authority component of the URI. Upon receiving a
server certificate in the TLS handshake, the client MUST verify that server certificate in the TLS handshake, the client MUST verify that
the certificate is an acceptable match for the URI's origin server the certificate is an acceptable match for the URI's origin server
using the process described in Section 4.3.4 of [SEMANTICS]. If the using the process described in Section 4.3.4 of [HTTP]. If the
certificate cannot be verified with respect to the URI's origin certificate cannot be verified with respect to the URI's origin
server, the client MUST NOT consider the server authoritative for server, the client MUST NOT consider the server authoritative for
that origin. that origin.
A client MAY attempt access to a resource with an "https" URI by A client MAY attempt access to a resource with an "https" URI by
resolving the host identifier to an IP address, establishing a QUIC resolving the host identifier to an IP address, establishing a QUIC
connection to that address on the indicated port (including connection to that address on the indicated port (including
validation of the server certificate as described above), and sending validation of the server certificate as described above), and sending
an HTTP/3 request message targeting the URI to the server over that an HTTP/3 request message targeting the URI to the server over that
secured connection. Unless some other mechanism is used to select secured connection. Unless some other mechanism is used to select
HTTP/3, the token "h3" is used in the Application Layer Protocol HTTP/3, the token "h3" is used in the Application-Layer Protocol
Negotiation (ALPN; see [RFC7301]) extension during the TLS handshake. Negotiation (ALPN; see [RFC7301]) extension during the TLS handshake.
Connectivity problems (e.g., blocking UDP) can result in QUIC Connectivity problems (e.g., blocking UDP) can result in a failure to
connection establishment failure; clients SHOULD attempt to use TCP- establish a QUIC connection; clients SHOULD attempt to use TCP-based
based versions of HTTP in this case. versions of HTTP in this case.
Servers MAY serve HTTP/3 on any UDP port; an alternative service Servers MAY serve HTTP/3 on any UDP port; an alternative service
advertisement always includes an explicit port, and URIs contain advertisement always includes an explicit port, and URIs contain
either an explicit port or a default port associated with the scheme. either an explicit port or a default port associated with the scheme.
3.1.1. HTTP Alternative Services 3.1.1. HTTP Alternative Services
An HTTP origin can advertise the availability of an equivalent HTTP/3 An HTTP origin can advertise the availability of an equivalent HTTP/3
endpoint via the Alt-Svc HTTP response header field or the HTTP/2 endpoint via the Alt-Svc HTTP response header field or the HTTP/2
ALTSVC frame ([ALTSVC]), using the "h3" ALPN token. ALTSVC frame ([ALTSVC]) using the "h3" ALPN token.
For example, an origin could indicate in an HTTP response that HTTP/3 For example, an origin could indicate in an HTTP response that HTTP/3
was available on UDP port 50781 at the same hostname by including the was available on UDP port 50781 at the same hostname by including the
following header field: following header field:
Alt-Svc: h3=":50781" Alt-Svc: h3=":50781"
On receipt of an Alt-Svc record indicating HTTP/3 support, a client On receipt of an Alt-Svc record indicating HTTP/3 support, a client
MAY attempt to establish a QUIC connection to the indicated host and MAY attempt to establish a QUIC connection to the indicated host and
port; if this connection is successful, the client can send HTTP port; if this connection is successful, the client can send HTTP
skipping to change at page 10, line 43 skipping to change at line 423
Server Name Indication (SNI; [RFC6066]) TLS extension unless an Server Name Indication (SNI; [RFC6066]) TLS extension unless an
alternative mechanism to indicate the target host is used. alternative mechanism to indicate the target host is used.
QUIC connections are established as described in [QUIC-TRANSPORT]. QUIC connections are established as described in [QUIC-TRANSPORT].
During connection establishment, HTTP/3 support is indicated by During connection establishment, HTTP/3 support is indicated by
selecting the ALPN token "h3" in the TLS handshake. Support for selecting the ALPN token "h3" in the TLS handshake. Support for
other application-layer protocols MAY be offered in the same other application-layer protocols MAY be offered in the same
handshake. handshake.
While connection-level options pertaining to the core QUIC protocol While connection-level options pertaining to the core QUIC protocol
are set in the initial crypto handshake, HTTP/3-specific settings are are set in the initial crypto handshake, settings specific to HTTP/3
conveyed in the SETTINGS frame. After the QUIC connection is are conveyed in the SETTINGS frame. After the QUIC connection is
established, a SETTINGS frame (Section 7.2.4) MUST be sent by each established, a SETTINGS frame MUST be sent by each endpoint as the
endpoint as the initial frame of their respective HTTP control initial frame of their respective HTTP control stream.
stream; see Section 6.2.1.
3.3. Connection Reuse 3.3. Connection Reuse
HTTP/3 connections are persistent across multiple requests. For best HTTP/3 connections are persistent across multiple requests. For best
performance, it is expected that clients will not close connections performance, it is expected that clients will not close connections
until it is determined that no further communication with a server is until it is determined that no further communication with a server is
necessary (for example, when a user navigates away from a particular necessary (for example, when a user navigates away from a particular
web page) or until the server closes the connection. web page) or until the server closes the connection.
Once a connection exists to a server endpoint, this connection MAY be Once a connection to a server endpoint exists, this connection MAY be
reused for requests with multiple different URI authority components. reused for requests with multiple different URI authority components.
To use an existing connection for a new origin, clients MUST validate To use an existing connection for a new origin, clients MUST validate
the certificate presented by the server for the new origin server the certificate presented by the server for the new origin server
using the process described in Section 4.3.4 of [SEMANTICS]. This using the process described in Section 4.3.4 of [HTTP]. This implies
implies that clients will need to retain the server certificate and that clients will need to retain the server certificate and any
any additional information needed to verify that certificate; clients additional information needed to verify that certificate; clients
which do not do so will be unable to reuse the connection for that do not do so will be unable to reuse the connection for
additional origins. additional origins.
If the certificate is not acceptable with regard to the new origin If the certificate is not acceptable with regard to the new origin
for any reason, the connection MUST NOT be reused and a new for any reason, the connection MUST NOT be reused and a new
connection SHOULD be established for the new origin. If the reason connection SHOULD be established for the new origin. If the reason
the certificate cannot be verified might apply to other origins the certificate cannot be verified might apply to other origins
already associated with the connection, the client SHOULD re-validate already associated with the connection, the client SHOULD revalidate
the server certificate for those origins. For instance, if the server certificate for those origins. For instance, if
validation of a certificate fails because the certificate has expired validation of a certificate fails because the certificate has expired
or been revoked, this might be used to invalidate all other origins or been revoked, this might be used to invalidate all other origins
for which that certificate was used to establish authority. for which that certificate was used to establish authority.
Clients SHOULD NOT open more than one HTTP/3 connection to a given IP Clients SHOULD NOT open more than one HTTP/3 connection to a given IP
address and UDP port, where the IP address and port might be derived address and UDP port, where the IP address and port might be derived
from a URI, a selected alternative service ([ALTSVC]), a configured from a URI, a selected alternative service ([ALTSVC]), a configured
proxy, or name resolution of any of these. A client MAY open proxy, or name resolution of any of these. A client MAY open
multiple HTTP/3 connections to the same IP address and UDP port using multiple HTTP/3 connections to the same IP address and UDP port using
skipping to change at page 11, line 52 skipping to change at line 475
long as possible but are permitted to terminate idle connections if long as possible but are permitted to terminate idle connections if
necessary. When either endpoint chooses to close the HTTP/3 necessary. When either endpoint chooses to close the HTTP/3
connection, the terminating endpoint SHOULD first send a GOAWAY frame connection, the terminating endpoint SHOULD first send a GOAWAY frame
(Section 5.2) so that both endpoints can reliably determine whether (Section 5.2) so that both endpoints can reliably determine whether
previously sent frames have been processed and gracefully complete or previously sent frames have been processed and gracefully complete or
terminate any necessary remaining tasks. terminate any necessary remaining tasks.
A server that does not wish clients to reuse HTTP/3 connections for a A server that does not wish clients to reuse HTTP/3 connections for a
particular origin can indicate that it is not authoritative for a particular origin can indicate that it is not authoritative for a
request by sending a 421 (Misdirected Request) status code in request by sending a 421 (Misdirected Request) status code in
response to the request; see Section 7.4 of [SEMANTICS]. response to the request; see Section 7.4 of [HTTP].
4. HTTP Request Lifecycle 4. Expressing HTTP Semantics in HTTP/3
4.1. HTTP Message Exchanges 4.1. HTTP Message Framing
A client sends an HTTP request on a request stream, which is a A client sends an HTTP request on a request stream, which is a
client-initiated bidirectional QUIC stream; see Section 6.1. A client-initiated bidirectional QUIC stream; see Section 6.1. A
client MUST send only a single request on a given stream. A server client MUST send only a single request on a given stream. A server
sends zero or more interim HTTP responses on the same stream as the sends zero or more interim HTTP responses on the same stream as the
request, followed by a single final HTTP response, as detailed below. request, followed by a single final HTTP response, as detailed below.
See Section 15 of [SEMANTICS] for a description of interim and final See Section 15 of [HTTP] for a description of interim and final HTTP
HTTP responses. responses.
Pushed responses are sent on a server-initiated unidirectional QUIC Pushed responses are sent on a server-initiated unidirectional QUIC
stream; see Section 6.2.2. A server sends zero or more interim HTTP stream; see Section 6.2.2. A server sends zero or more interim HTTP
responses, followed by a single final HTTP response, in the same responses, followed by a single final HTTP response, in the same
manner as a standard response. Push is described in more detail in manner as a standard response. Push is described in more detail in
Section 4.4. Section 4.6.
On a given stream, receipt of multiple requests or receipt of an On a given stream, receipt of multiple requests or receipt of an
additional HTTP response following a final HTTP response MUST be additional HTTP response following a final HTTP response MUST be
treated as malformed (Section 4.1.3). treated as malformed.
An HTTP message (request or response) consists of: An HTTP message (request or response) consists of:
1. the header section, sent as a single HEADERS frame (see 1. the header section, including message control data, sent as a
Section 7.2.2), single HEADERS frame,
2. optionally, the content, if present, sent as a series of DATA 2. optionally, the content, if present, sent as a series of DATA
frames (see Section 7.2.1), and frames, and
3. optionally, the trailer section, if present, sent as a single 3. optionally, the trailer section, if present, sent as a single
HEADERS frame. HEADERS frame.
Header and trailer sections are described in Sections 6.3 and 6.5 of Header and trailer sections are described in Sections 6.3 and 6.5 of
[SEMANTICS]; the content is described in Section 6.4 of [SEMANTICS]. [HTTP]; the content is described in Section 6.4 of [HTTP].
Receipt of an invalid sequence of frames MUST be treated as a Receipt of an invalid sequence of frames MUST be treated as a
connection error of type H3_FRAME_UNEXPECTED; see Section 8. In connection error of type H3_FRAME_UNEXPECTED. In particular, a DATA
particular, a DATA frame before any HEADERS frame, or a HEADERS or frame before any HEADERS frame, or a HEADERS or DATA frame after the
DATA frame after the trailing HEADERS frame, is considered invalid. trailing HEADERS frame, is considered invalid. Other frame types,
Other frame types, especially unknown frame types, might be permitted especially unknown frame types, might be permitted subject to their
subject to their own rules; see Section 9. own rules; see Section 9.
A server MAY send one or more PUSH_PROMISE frames (Section 7.2.5) A server MAY send one or more PUSH_PROMISE frames before, after, or
before, after, or interleaved with the frames of a response message. interleaved with the frames of a response message. These
These PUSH_PROMISE frames are not part of the response; see PUSH_PROMISE frames are not part of the response; see Section 4.6 for
Section 4.4 for more details. PUSH_PROMISE frames are not permitted more details. PUSH_PROMISE frames are not permitted on push streams;
on push streams; a pushed response that includes PUSH_PROMISE frames a pushed response that includes PUSH_PROMISE frames MUST be treated
MUST be treated as a connection error of type H3_FRAME_UNEXPECTED; as a connection error of type H3_FRAME_UNEXPECTED.
see Section 8.
Frames of unknown types (Section 9), including reserved frames Frames of unknown types (Section 9), including reserved frames
(Section 7.2.8) MAY be sent on a request or push stream before, (Section 7.2.8) MAY be sent on a request or push stream before,
after, or interleaved with other frames described in this section. after, or interleaved with other frames described in this section.
The HEADERS and PUSH_PROMISE frames might reference updates to the The HEADERS and PUSH_PROMISE frames might reference updates to the
QPACK dynamic table. While these updates are not directly part of QPACK dynamic table. While these updates are not directly part of
the message exchange, they must be received and processed before the the message exchange, they must be received and processed before the
message can be consumed. See Section 4.1.1 for more details. message can be consumed. See Section 4.2 for more details.
Transfer codings (see Section 6.1 of [HTTP11]) are not defined for Transfer codings (see Section 7 of [HTTP/1.1]) are not defined for
HTTP/3; the Transfer-Encoding header field MUST NOT be used. HTTP/3; the Transfer-Encoding header field MUST NOT be used.
A response MAY consist of multiple messages when and only when one or A response MAY consist of multiple messages when and only when one or
more interim responses (1xx; see Section 15.2 of [SEMANTICS]) precede more interim responses (1xx; see Section 15.2 of [HTTP]) precede a
a final response to the same request. Interim responses do not final response to the same request. Interim responses do not contain
contain content or trailer sections. content or trailer sections.
An HTTP request/response exchange fully consumes a client-initiated An HTTP request/response exchange fully consumes a client-initiated
bidirectional QUIC stream. After sending a request, a client MUST bidirectional QUIC stream. After sending a request, a client MUST
close the stream for sending. Unless using the CONNECT method (see close the stream for sending. Unless using the CONNECT method (see
Section 4.2), clients MUST NOT make stream closure dependent on Section 4.4), clients MUST NOT make stream closure dependent on
receiving a response to their request. After sending a final receiving a response to their request. After sending a final
response, the server MUST close the stream for sending. At this response, the server MUST close the stream for sending. At this
point, the QUIC stream is fully closed. point, the QUIC stream is fully closed.
When a stream is closed, this indicates the end of the final HTTP When a stream is closed, this indicates the end of the final HTTP
message. Because some messages are large or unbounded, endpoints message. Because some messages are large or unbounded, endpoints
SHOULD begin processing partial HTTP messages once enough of the SHOULD begin processing partial HTTP messages once enough of the
message has been received to make progress. If a client-initiated message has been received to make progress. If a client-initiated
stream terminates without enough of the HTTP message to provide a stream terminates without enough of the HTTP message to provide a
complete response, the server SHOULD abort its response stream with complete response, the server SHOULD abort its response stream with
the error code H3_REQUEST_INCOMPLETE; see Section 8. the error code H3_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 the server does request that has not been sent and received. When the server does
not need to receive the remainder of the request, it MAY abort not need to receive the remainder of the request, it MAY abort
reading the request stream, send a complete response, and cleanly reading the request stream, send a complete response, and cleanly
close the sending part of the stream. The error code H3_NO_ERROR close the sending part of the stream. The error code H3_NO_ERROR
SHOULD be used when requesting that the client stop sending on the SHOULD be used when requesting that the client stop sending on the
request stream. Clients MUST NOT discard complete responses as a request stream. Clients MUST NOT discard complete responses as a
result of having their request terminated abruptly, though clients result of having their request terminated abruptly, though clients
can always discard responses at their discretion for other reasons. can always discard responses at their discretion for other reasons.
If the server sends a partial or complete response but does not abort If the server sends a partial or complete response but does not abort
reading the request, clients SHOULD continue sending the body of the reading the request, clients SHOULD continue sending the content of
request and close the stream normally. the request and close the stream normally.
4.1.1. Field Formatting and Compression
HTTP messages carry metadata as a series of key-value pairs called
HTTP fields; see Sections 6.3 and 6.5 of [SEMANTICS]. For a listing
of registered HTTP fields, see the "Hypertext Transfer Protocol
(HTTP) Field Name Registry" maintained at
https://www.iana.org/assignments/http-fields/.
*Note:* This registry will not exist until [SEMANTICS] is 4.1.1. Request Cancellation and Rejection
approved. *RFC Editor*, please remove this note prior to
publication.
Field names are strings containing a subset of ASCII characters. Once a request stream has been opened, the request MAY be cancelled
Properties of HTTP field names and values are discussed in more by either endpoint. Clients cancel requests if the response is no
detail in Section 5.1 of [SEMANTICS]. As in HTTP/2, characters in longer of interest; servers cancel requests if they are unable to or
field names MUST be converted to lowercase prior to their encoding. choose not to respond. When possible, it is RECOMMENDED that servers
A request or response containing uppercase characters in field names send an HTTP response with an appropriate status code rather than
MUST be treated as malformed (Section 4.1.3). cancelling a request it has already begun processing.
Like HTTP/2, HTTP/3 does not use the Connection header field to Implementations SHOULD cancel requests by abruptly terminating any
indicate connection-specific fields; in this protocol, connection- directions of a stream that are still open. To do so, an
specific metadata is conveyed by other means. An endpoint MUST NOT implementation resets the sending parts of streams and aborts reading
generate an HTTP/3 field section containing connection-specific on the receiving parts of streams; see Section 2.4 of
fields; any message containing connection-specific fields MUST be [QUIC-TRANSPORT].
treated as malformed (Section 4.1.3).
The only exception to this is the TE header field, which MAY be When the server cancels a request without performing any application
present in an HTTP/3 request header; when it is, it MUST NOT contain processing, the request is considered "rejected". The server SHOULD
any value other than "trailers". abort its response stream with the error code H3_REQUEST_REJECTED.
In this context, "processed" means that some 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 requests rejected by the
server as though they had never been sent at all, thereby allowing
them to be retried later.
An intermediary transforming an HTTP/1.x message to HTTP/3 MUST Servers MUST NOT use the H3_REQUEST_REJECTED error code for requests
remove connection-specific header fields as discussed in that were partially or fully processed. When a server abandons a
Section 7.6.1 of [SEMANTICS], or their messages will be treated by response after partial processing, it SHOULD abort its response
other HTTP/3 endpoints as malformed (Section 4.1.3). stream with the error code H3_REQUEST_CANCELLED.
4.1.1.1. Pseudo-Header Fields Client SHOULD use the error code H3_REQUEST_CANCELLED to cancel
requests. Upon receipt of this error code, a server MAY abruptly
terminate the response using the error code H3_REQUEST_REJECTED if no
processing was performed. Clients MUST NOT use the
H3_REQUEST_REJECTED error code, except when a server has requested
closure of the request stream with this error code.
Like HTTP/2, HTTP/3 employs a series of pseudo-header fields where If a stream is cancelled after receiving a complete response, the
the field name begins with the ':' character (ASCII 0x3a). These client MAY ignore the cancellation and use the response. However, if
pseudo-header fields convey the target URI, the method of the a stream is cancelled after receiving a partial response, the
request, and the status code for the response. response SHOULD NOT be used. Only idempotent actions such as GET,
PUT, or DELETE can be safely retried; a client SHOULD NOT
automatically retry a request with a non-idempotent method unless it
has some means to know that the request semantics are idempotent
independent of the method or some means to detect that the original
request was never applied. See Section 9.2.2 of [HTTP] for more
details.
Pseudo-header fields are not HTTP fields. Endpoints MUST NOT 4.1.2. Malformed Requests and Responses
generate pseudo-header fields other than those defined in this
document; however, an extension could negotiate a modification of
this restriction; see Section 9.
Pseudo-header fields are only valid in the context in which they are A malformed request or response is one that is an otherwise valid
defined. Pseudo-header fields defined for requests MUST NOT appear sequence of frames but is invalid due to:
in responses; pseudo-header fields defined for responses MUST NOT
appear in requests. Pseudo-header fields MUST NOT appear in trailer
sections. Endpoints MUST treat a request or response that contains
undefined or invalid pseudo-header fields as malformed
(Section 4.1.3).
All pseudo-header fields MUST appear in the header section before * the presence of prohibited fields or pseudo-header fields,
regular header fields. Any request or response that contains a
pseudo-header field that appears in a header section after a regular
header field MUST be treated as malformed (Section 4.1.3).
The following pseudo-header fields are defined for requests: * the absence of mandatory pseudo-header fields,
":method": Contains the HTTP method (Section 9 of [SEMANTICS]) * invalid values for pseudo-header fields,
":scheme": Contains the scheme portion of the target URI * pseudo-header fields after fields,
(Section 3.1 of [URI])
":scheme" is not restricted to URIs with scheme "http" and * an invalid sequence of HTTP messages,
"https". A proxy or gateway can translate requests for non-HTTP
schemes, enabling the use of HTTP to interact with non-HTTP
services.
See Section 3.1.2 for guidance on using a scheme other than * the inclusion of uppercase field names, or
"https".
":authority": Contains the authority portion of the target URI * the inclusion of invalid characters in field names or values.
(Section 3.2 of [URI]). The authority MUST NOT include the
deprecated "userinfo" subcomponent for URIs of scheme "http" or
"https".
To ensure that the HTTP/1.1 request line can be reproduced A request or response that is defined as having content when it
accurately, this pseudo-header field MUST be omitted when contains a Content-Length header field (Section 8.6 of [HTTP]) is
translating from an HTTP/1.1 request that has a request target in malformed if the value of the Content-Length header field does not
origin or asterisk form; see Section 7.1 of [SEMANTICS]. Clients equal the sum of the DATA frame lengths received. A response that is
that generate HTTP/3 requests directly SHOULD use the ":authority" defined as never having content, even when a Content-Length is
pseudo-header field instead of the Host field. An intermediary present, can have a non-zero Content-Length header field even though
that converts an HTTP/3 request to HTTP/1.1 MUST create a Host no content is included in DATA frames.
field if one is not present in a request by copying the value of
the ":authority" pseudo-header field.
":path": Contains the path and query parts of the target URI (the Intermediaries that process HTTP requests or responses (i.e., any
"path-absolute" production and optionally a '?' character followed intermediary not acting as a tunnel) MUST NOT forward a malformed
by the "query" production; see Sections 3.3 and 3.4 of [URI]. A request or response. Malformed requests or responses that are
request in asterisk form includes the value '*' for the ":path" detected MUST be treated as a stream error of type H3_MESSAGE_ERROR.
pseudo-header field.
This pseudo-header field MUST NOT be empty for "http" or "https" For malformed requests, a server MAY send an HTTP response indicating
URIs; "http" or "https" URIs that do not contain a path component the error prior to closing or resetting the stream. Clients MUST NOT
MUST include a value of '/'. The exception to this rule is an accept a malformed response. Note that these requirements are
OPTIONS request for an "http" or "https" URI that does not include intended to protect against several types of common attacks against
a path component; these MUST include a ":path" pseudo-header field HTTP; they are deliberately strict because being permissive can
with a value of '*'; see Section 7.1 of [SEMANTICS]. expose implementations to these vulnerabilities.
All HTTP/3 requests MUST include exactly one value for the ":method", 4.2. HTTP Fields
":scheme", and ":path" pseudo-header fields, unless it is a CONNECT
request; see Section 4.2.
If the ":scheme" pseudo-header field identifies a scheme that has a HTTP messages carry metadata as a series of key-value pairs called
mandatory authority component (including "http" and "https"), the "HTTP fields"; see Sections 6.3 and 6.5 of [HTTP]. For a listing of
request MUST contain either an ":authority" pseudo-header field or a registered HTTP fields, see the "Hypertext Transfer Protocol (HTTP)
"Host" header field. If these fields are present, they MUST NOT be Field Name Registry" maintained at <https://www.iana.org/assignments/
empty. If both fields are present, they MUST contain the same value. http-fields/>. Like HTTP/2, HTTP/3 has additional considerations
If the scheme does not have a mandatory authority component and none related to the use of characters in field names, the Connection
is provided in the request target, the request MUST NOT contain the header field, and pseudo-header fields.
":authority" pseudo-header or "Host" header fields.
An HTTP request that omits mandatory pseudo-header fields or contains Field names are strings containing a subset of ASCII characters.
invalid values for those pseudo-header fields is malformed Properties of HTTP field names and values are discussed in more
(Section 4.1.3). detail in Section 5.1 of [HTTP]. Characters in field names MUST be
converted to lowercase prior to their encoding. A request or
response containing uppercase characters in field names MUST be
treated as malformed.
HTTP/3 does not define a way to carry the version identifier that is HTTP/3 does not use the Connection header field to indicate
included in the HTTP/1.1 request line. connection-specific fields; in this protocol, connection-specific
metadata is conveyed by other means. An endpoint MUST NOT generate
an HTTP/3 field section containing connection-specific fields; any
message containing connection-specific fields MUST be treated as
malformed.
For responses, a single ":status" pseudo-header field is defined that The only exception to this is the TE header field, which MAY be
carries the HTTP status code; see Section 15 of [SEMANTICS]. This present in an HTTP/3 request header; when it is, it MUST NOT contain
pseudo-header field MUST be included in all responses; otherwise, the any value other than "trailers".
response is malformed (Section 4.1.3).
HTTP/3 does not define a way to carry the version or reason phrase An intermediary transforming an HTTP/1.x message to HTTP/3 MUST
that is included in an HTTP/1.1 status line. remove connection-specific header fields as discussed in
Section 7.6.1 of [HTTP], or their messages will be treated by other
HTTP/3 endpoints as malformed.
4.1.1.2. Field Compression 4.2.1. Field Compression
[QPACK] describes a variation of HPACK that gives an encoder some [QPACK] describes a variation of HPACK that gives an encoder some
control over how much head-of-line blocking can be caused by control over how much head-of-line blocking can be caused by
compression. This allows an encoder to balance compression compression. This allows an encoder to balance compression
efficiency with latency. HTTP/3 uses QPACK to compress header and efficiency with latency. HTTP/3 uses QPACK to compress header and
trailer sections, including the pseudo-header fields present in the trailer sections, including the control data present in the header
header section. section.
To allow for better compression efficiency, the "Cookie" field To allow for better compression efficiency, the Cookie header field
([RFC6265]) MAY be split into separate field lines, each with one or ([COOKIES]) MAY be split into separate field lines, each with one or
more cookie-pairs, before compression. If a decompressed field more cookie-pairs, before compression. If a decompressed field
section contains multiple cookie field lines, these MUST be section contains multiple cookie field lines, these MUST be
concatenated into a single byte string using the two-byte delimiter concatenated into a single byte string using the two-byte delimiter
of 0x3b, 0x20 (the ASCII string "; ") before being passed into a of "; " (ASCII 0x3b, 0x20) before being passed into a context other
context other than HTTP/2 or HTTP/3, such as an HTTP/1.1 connection, than HTTP/2 or HTTP/3, such as an HTTP/1.1 connection, or a generic
or a generic HTTP server application. HTTP server application.
4.1.1.3. Header Size Constraints 4.2.2. Header Size Constraints
An HTTP/3 implementation MAY impose a limit on the maximum size of An HTTP/3 implementation MAY impose a limit on the maximum size of
the message header it will accept on an individual HTTP message. A the message header it will accept on an individual HTTP message. A
server that receives a larger header section than it is willing to server that receives a larger header section than it is willing to
handle can send an HTTP 431 (Request Header Fields Too Large) status handle can send an HTTP 431 (Request Header Fields Too Large) status
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 field list is calculated based on the process. The size of a field list is calculated based on the
uncompressed size of fields, including the length of the name and uncompressed size of fields, including the length of the name and
value in bytes plus an overhead of 32 bytes for each field. value in bytes plus an overhead of 32 bytes for each field.
If an implementation wishes to advise its peer of this limit, it can If an implementation wishes to advise its peer of this limit, it can
be conveyed as a number of bytes in the be conveyed as a number of bytes in the
SETTINGS_MAX_FIELD_SECTION_SIZE parameter. An implementation that SETTINGS_MAX_FIELD_SECTION_SIZE parameter. An implementation that
has received this parameter SHOULD NOT send an HTTP message header has received this parameter SHOULD NOT send an HTTP message header
that exceeds the indicated size, as the peer will likely refuse to that exceeds the indicated size, as the peer will likely refuse to
process it. However, an HTTP message can traverse one or more process it. However, an HTTP message can traverse one or more
intermediaries before reaching the origin server; see Section 3.7 of intermediaries before reaching the origin server; see Section 3.7 of
[SEMANTICS]. Because this limit is applied separately by each [HTTP]. Because this limit is applied separately by each
implementation which processes the message, messages below this limit implementation that processes the message, messages below this limit
are not guaranteed to be accepted. are not guaranteed to be accepted.
4.1.2. Request Cancellation and Rejection 4.3. HTTP Control Data
Once a request stream has been opened, the request MAY be cancelled Like HTTP/2, HTTP/3 employs a series of pseudo-header fields, where
by either endpoint. Clients cancel requests if the response is no the field name begins with the : character (ASCII 0x3a). These
longer of interest; servers cancel requests if they are unable to or pseudo-header fields convey message control data; see Section 6.2 of
choose not to respond. When possible, it is RECOMMENDED that servers [HTTP].
send an HTTP response with an appropriate status code rather than
canceling a request it has already begun processing.
Implementations SHOULD cancel requests by abruptly terminating any Pseudo-header fields are not HTTP fields. Endpoints MUST NOT
directions of a stream that are still open. This means resetting the generate pseudo-header fields other than those defined in this
sending parts of streams and aborting reading on receiving parts of document. However, an extension could negotiate a modification of
streams; see Section 2.4 of [QUIC-TRANSPORT]. this restriction; see Section 9.
When the server cancels a request without performing any application Pseudo-header fields are only valid in the context in which they are
processing, the request is considered "rejected." The server SHOULD defined. Pseudo-header fields defined for requests MUST NOT appear
abort its response stream with the error code H3_REQUEST_REJECTED. in responses; pseudo-header fields defined for responses MUST NOT
In this context, "processed" means that some data from the stream was appear in requests. Pseudo-header fields MUST NOT appear in trailer
passed to some higher layer of software that might have taken some sections. Endpoints MUST treat a request or response that contains
action as a result. The client can treat requests rejected by the undefined or invalid pseudo-header fields as malformed.
server as though they had never been sent at all, thereby allowing
them to be retried later.
Servers MUST NOT use the H3_REQUEST_REJECTED error code for requests All pseudo-header fields MUST appear in the header section before
that were partially or fully processed. When a server abandons a regular header fields. Any request or response that contains a
response after partial processing, it SHOULD abort its response pseudo-header field that appears in a header section after a regular
stream with the error code H3_REQUEST_CANCELLED. header field MUST be treated as malformed.
Client SHOULD use the error code H3_REQUEST_CANCELLED to cancel 4.3.1. Request Pseudo-Header Fields
requests. Upon receipt of this error code, a server MAY abruptly
terminate the response using the error code H3_REQUEST_REJECTED if no
processing was performed. Clients MUST NOT use the
H3_REQUEST_REJECTED error code, except when a server has requested
closure of the request stream with this error code.
If a stream is canceled after receiving a complete response, the The following pseudo-header fields are defined for requests:
client MAY ignore the cancellation and use the response. However, if
a stream is cancelled after receiving a partial response, the
response SHOULD NOT be used. Only idempotent actions such as GET,
PUT, or DELETE can be safely retried; a client SHOULD NOT
automatically retry a request with a non-idempotent method unless it
has some means to know that the request semantics are idempotent
independent of the method or some means to detect that the original
request was never applied. See Section 9.2.2 of [SEMANTICS] for more
details.
4.1.3. Malformed Requests and Responses ":method": Contains the HTTP method (Section 9 of [HTTP])
A malformed request or response is one that is an otherwise valid ":scheme": Contains the scheme portion of the target URI
sequence of frames but is invalid due to: (Section 3.1 of [URI]).
* the presence of prohibited fields or pseudo-header fields, The :scheme pseudo-header is not restricted to URIs with scheme
"http" and "https". A proxy or gateway can translate requests for
non-HTTP schemes, enabling the use of HTTP to interact with non-
HTTP services.
* the absence of mandatory pseudo-header fields, See Section 3.1.2 for guidance on using a scheme other than
"https".
* invalid values for pseudo-header fields, ":authority": Contains the authority portion of the target URI
* pseudo-header fields after fields, (Section 3.2 of [URI]). The authority MUST NOT include the
deprecated userinfo subcomponent for URIs of scheme "http" or
"https".
* an invalid sequence of HTTP messages, To ensure that the HTTP/1.1 request line can be reproduced
accurately, this pseudo-header field MUST be omitted when
translating from an HTTP/1.1 request that has a request target in
a method-specific form; see Section 7.1 of [HTTP]. Clients that
generate HTTP/3 requests directly SHOULD use the :authority
pseudo-header field instead of the Host header field. An
intermediary that converts an HTTP/3 request to HTTP/1.1 MUST
create a Host field if one is not present in a request by copying
the value of the :authority pseudo-header field.
* the inclusion of uppercase field names, or ":path": Contains the path and query parts of the target URI (the
"path-absolute" production and optionally a ? character (ASCII
0x3f) followed by the "query" production; see Sections 3.3 and 3.4
of [URI].
* the inclusion of invalid characters in field names or values. This pseudo-header field MUST NOT be empty for "http" or "https"
URIs; "http" or "https" URIs that do not contain a path component
MUST include a value of / (ASCII 0x2f). An OPTIONS request that
does not include a path component includes the value * (ASCII
0x2a) for the :path pseudo-header field; see Section 7.1 of
[HTTP].
A request or response that is defined as having content when it All HTTP/3 requests MUST include exactly one value for the :method,
contains a Content-Length header field (Section 6.4.1 of :scheme, and :path pseudo-header fields, unless the request is a
[SEMANTICS]), is malformed if the value of a Content-Length header CONNECT request; see Section 4.4.
field does not equal the sum of the DATA frame lengths received. A
response that is defined as never having content, even when a
Content-Length is present, can have a non-zero Content-Length field
even though no content is included in DATA frames.
Intermediaries that process HTTP requests or responses (i.e., any If the :scheme pseudo-header field identifies a scheme that has a
intermediary not acting as a tunnel) MUST NOT forward a malformed mandatory authority component (including "http" and "https"), the
request or response. Malformed requests or responses that are request MUST contain either an :authority pseudo-header field or a
detected MUST be treated as a stream error (Section 8) of type Host header field. If these fields are present, they MUST NOT be
H3_MESSAGE_ERROR. empty. If both fields are present, they MUST contain the same value.
If the scheme does not have a mandatory authority component and none
is provided in the request target, the request MUST NOT contain the
:authority pseudo-header or Host header fields.
For malformed requests, a server MAY send an HTTP response indicating An HTTP request that omits mandatory pseudo-header fields or contains
the error prior to closing or resetting the stream. Clients MUST NOT invalid values for those pseudo-header fields is malformed.
accept a malformed response. Note that these requirements are
intended to protect against several types of common attacks against
HTTP; they are deliberately strict because being permissive can
expose implementations to these vulnerabilities.
4.2. The CONNECT Method HTTP/3 does not define a way to carry the version identifier that is
included in the HTTP/1.1 request line. HTTP/3 requests implicitly
have a protocol version of "3.0".
4.3.2. Response Pseudo-Header Fields
For responses, a single ":status" pseudo-header field is defined that
carries the HTTP status code; see Section 15 of [HTTP]. This pseudo-
header field MUST be included in all responses; otherwise, the
response is malformed (see Section 4.1.2).
HTTP/3 does not define a way to carry the version or reason phrase
that is included in an HTTP/1.1 status line. HTTP/3 responses
implicitly have a protocol version of "3.0".
4.4. The CONNECT Method
The CONNECT method requests that the recipient establish a tunnel to The CONNECT method requests that the recipient establish a tunnel to
the destination origin server identified by the request-target; see the destination origin server identified by the request-target; see
Section 9.3.6 of [SEMANTICS]. It is primarily used with HTTP proxies Section 9.3.6 of [HTTP]. It is primarily used with HTTP proxies to
to establish a TLS session with an origin server for the purposes of establish a TLS session with an origin server for the purposes of
interacting with "https" resources. interacting with "https" resources.
In HTTP/1.x, CONNECT is used to convert an entire HTTP connection In HTTP/1.x, CONNECT is used to convert an entire HTTP connection
into a tunnel to a remote host. In HTTP/2 and HTTP/3, the CONNECT into a tunnel to a remote host. In HTTP/2 and HTTP/3, the CONNECT
method is used to establish a tunnel over a single stream. method is used to establish a tunnel over a single stream.
A CONNECT request MUST be constructed as follows: A CONNECT request MUST be constructed as follows:
* The ":method" pseudo-header field is set to "CONNECT" * The :method pseudo-header field is set to "CONNECT"
* The ":scheme" and ":path" pseudo-header fields are omitted * The :scheme and :path pseudo-header fields are omitted
* The ":authority" pseudo-header field contains the host and port to
* The :authority pseudo-header field contains the host and port to
connect to (equivalent to the authority-form of the request-target connect to (equivalent to the authority-form of the request-target
of CONNECT requests; see Section 7.1 of [SEMANTICS]) of CONNECT requests; see Section 7.1 of [HTTP]).
The request stream remains open at the end of the request to carry The request stream remains open at the end of the request to carry
the data to be transferred. A CONNECT request that does not conform the data to be transferred. A CONNECT request that does not conform
to these restrictions is malformed; see Section 4.1.3. to these restrictions is malformed.
A proxy that supports CONNECT establishes a TCP connection A proxy that supports CONNECT establishes a TCP connection
([RFC0793]) to the server identified in the ":authority" pseudo- ([RFC0793]) to the server identified in the :authority pseudo-header
header field. Once this connection is successfully established, the field. Once this connection is successfully established, the proxy
proxy sends a HEADERS frame containing a 2xx series status code to sends a HEADERS frame containing a 2xx series status code to the
the client, as defined in Section 15.3 of [SEMANTICS]. client, as defined in Section 15.3 of [HTTP].
All DATA frames on the stream correspond to data sent or received on All DATA frames on the stream correspond to data sent or received on
the TCP connection. The payload of any DATA frame sent by the client the TCP connection. The payload of any DATA frame sent by the client
is transmitted by the proxy to the TCP server; data received from the is transmitted by the proxy to the TCP server; data received from the
TCP server is packaged into DATA frames by the proxy. Note that the TCP server is packaged into DATA frames by the proxy. Note that the
size and number of TCP segments is not guaranteed to map predictably size and number of TCP segments is not guaranteed to map predictably
to the size and number of HTTP DATA or QUIC STREAM frames. to the 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 known frame type MUST be treated as a connection error of any other known frame type MUST be treated as a connection error
of type H3_FRAME_UNEXPECTED; see Section 8. of type H3_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 close the send stream that it sends to the the FIN bit set, it will close the send stream that it sends to the
client. TCP connections that remain half-closed in a single client. TCP connections that 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 by abruptly terminating the A TCP connection error is signaled by abruptly terminating the
stream. A proxy treats any error in the TCP connection, which stream. A proxy treats any error in the TCP connection, which
includes receiving a TCP segment with the RST bit set, as a stream includes receiving a TCP segment with the RST bit set, as a stream
error of type H3_CONNECT_ERROR; see Section 8. Correspondingly, if a error of type H3_CONNECT_ERROR.
proxy detects an error with the stream or the QUIC connection, it
MUST close the TCP connection. If the underlying TCP implementation Correspondingly, if a proxy detects an error with the stream or the
permits it, the proxy SHOULD send a TCP segment with the RST bit set. QUIC connection, it MUST close the TCP connection. If the proxy
detects that the client has reset the stream or aborted reading from
the stream, it MUST close the TCP connection. If the stream is reset
or reading is aborted by the client, a proxy SHOULD perform the same
operation on the other direction in order to ensure that both
directions of the stream are cancelled. In all these cases, if the
underlying TCP implementation permits it, the proxy SHOULD send a TCP
segment with the RST bit set.
Since CONNECT creates a tunnel to an arbitrary server, proxies that Since CONNECT creates a tunnel to an arbitrary server, proxies that
support CONNECT SHOULD restrict its use to a set of known ports or a support CONNECT SHOULD restrict its use to a set of known ports or a
list of safe request targets; see Section 9.3.6 of [SEMANTICS] for list of safe request targets; see Section 9.3.6 of [HTTP] for more
more detail. details.
4.3. HTTP Upgrade 4.5. HTTP Upgrade
HTTP/3 does not support the HTTP Upgrade mechanism (Section 7.8 of HTTP/3 does not support the HTTP Upgrade mechanism (Section 7.8 of
[SEMANTICS]) or 101 (Switching Protocols) informational status code [HTTP]) or the 101 (Switching Protocols) informational status code
(Section 15.2.2 of [SEMANTICS]). (Section 15.2.2 of [HTTP]).
4.4. Server Push 4.6. Server Push
Server push is an interaction mode that permits a server to push a Server push is an interaction mode that permits a server to push a
request-response exchange to a client in anticipation of the client request-response exchange to a client in anticipation of the client
making the indicated request. This trades off network usage against making the indicated request. This trades off network usage against
a potential latency gain. HTTP/3 server push is similar to what is a potential latency gain. HTTP/3 server push is similar to what is
described in Section 8.2 of [HTTP2], but uses different mechanisms. described in Section 8.2 of [HTTP/2], but it uses different
mechanisms.
Each server push is assigned a unique Push ID by the server. The Each server push is assigned a unique push ID by the server. The
Push ID is used to refer to the push in various contexts throughout push ID is used to refer to the push in various contexts throughout
the lifetime of the HTTP/3 connection. the lifetime of the HTTP/3 connection.
The Push ID space begins at zero, and ends at a maximum value set by The push ID space begins at zero and ends at a maximum value set by
the MAX_PUSH_ID frame; see Section 7.2.7. In particular, a server is the MAX_PUSH_ID frame. In particular, a server is not able to push
not able to push until after the client sends a MAX_PUSH_ID frame. A until after the client sends a MAX_PUSH_ID frame. A client sends
client sends MAX_PUSH_ID frames to control the number of pushes that MAX_PUSH_ID frames to control the number of pushes that a server can
a server can promise. A server SHOULD use Push IDs sequentially, promise. A server SHOULD use push IDs sequentially, beginning from
beginning from zero. A client MUST treat receipt of a push stream as zero. A client MUST treat receipt of a push stream as a connection
a connection error of type H3_ID_ERROR (Section 8) when no error of type H3_ID_ERROR when no MAX_PUSH_ID frame has been sent or
MAX_PUSH_ID frame has been sent or when the stream references a Push when the stream references a push ID that is greater than the maximum
ID that is greater than the maximum Push ID. push ID.
The Push ID is used in one or more PUSH_PROMISE frames The push ID is used in one or more PUSH_PROMISE frames that carry the
(Section 7.2.5) that carry the header section of the request message. control data and header fields of the request message. These frames
These frames are sent on the request stream that generated the push. are sent on the request stream that generated the push. This allows
This allows the server push to be associated with a client request. the server push to be associated with a client request. When the
When the same Push ID is promised on multiple request streams, the same push ID is promised on multiple request streams, the
decompressed request field sections MUST contain the same fields in decompressed request field sections MUST contain the same fields in
the same order, and both the name and the value in each field MUST be the same order, and both the name and the value in each field MUST be
identical. identical.
The Push ID is then included with the push stream that ultimately The push ID is then included with the push stream that ultimately
fulfills those promises; see Section 6.2.2. The push stream fulfills those promises. The push stream identifies the push ID of
identifies the Push ID of the promise that it fulfills, then contains the promise that it fulfills, then contains a response to the
a response to the promised request as described in Section 4.1. promised request as described in Section 4.1.
Finally, the Push ID can be used in CANCEL_PUSH frames; see Finally, the push ID can be used in CANCEL_PUSH frames; see
Section 7.2.3. Clients use this frame to indicate they do not wish Section 7.2.3. Clients use this frame to indicate they do not wish
to receive a promised resource. Servers use this frame to indicate to receive a promised resource. Servers use this frame to indicate
they will not be fulfilling a previous promise. they will not be fulfilling a previous promise.
Not all requests can be pushed. A server MAY push requests that have Not all requests can be pushed. A server MAY push requests that have
the following properties: the following properties:
* cacheable; see Section 9.2.3 of [SEMANTICS] * cacheable; see Section 9.2.3 of [HTTP]
* safe; see Section 9.2.1 of [SEMANTICS] * safe; see Section 9.2.1 of [HTTP]
* does not include a request body or trailer section * does not include request content or a trailer section
The server MUST include a value in the ":authority" pseudo-header The server MUST include a value in the :authority pseudo-header field
field for which the server is authoritative. If the client has not for which the server is authoritative. If the client has not yet
yet validated the connection for the origin indicated by the pushed validated the connection for the origin indicated by the pushed
request, it MUST perform the same verification process it would do request, it MUST perform the same verification process it would do
before sending a request for that origin on the connection; see before sending a request for that origin on the connection; see
Section 3.3. If this verification fails, the client MUST NOT Section 3.3. If this verification fails, the client MUST NOT
consider the server authoritative for that origin. consider the server authoritative for that origin.
Clients SHOULD send a CANCEL_PUSH frame upon receipt of a Clients SHOULD send a CANCEL_PUSH frame upon receipt of a
PUSH_PROMISE frame carrying a request that is not cacheable, is not PUSH_PROMISE frame carrying a request that is not cacheable, is not
known to be safe, that indicates the presence of a request body, or known to be safe, that indicates the presence of request content, or
for which it does not consider the server authoritative. Any for which it does not consider the server authoritative. Any
corresponding responses MUST NOT be used or cached. corresponding responses MUST NOT be used or cached.
Each pushed response is associated with one or more client requests. Each pushed response is associated with one or more client requests.
The push is associated with the request stream on which the The push is associated with the request stream on which the
PUSH_PROMISE frame was received. The same server push can be PUSH_PROMISE frame was received. The same server push can be
associated with additional client requests using a PUSH_PROMISE frame associated with additional client requests using a PUSH_PROMISE frame
with the same Push ID on multiple request streams. These with the same push ID on multiple request streams. These
associations do not affect the operation of the protocol, but MAY be associations do not affect the operation of the protocol, but they
considered by user agents when deciding how to use pushed resources. MAY be considered by user agents when deciding how to use pushed
resources.
Ordering of a PUSH_PROMISE frame in relation to certain parts of the Ordering of a PUSH_PROMISE frame in relation to certain parts of the
response is important. The server SHOULD send PUSH_PROMISE frames response is important. The server SHOULD send PUSH_PROMISE frames
prior to sending HEADERS or DATA frames that reference the promised prior to sending HEADERS or DATA frames that reference the promised
responses. This reduces the chance that a client requests a resource responses. This reduces the chance that a client requests a resource
that will be pushed by the server. that will be pushed by the server.
Due to reordering, push stream data can arrive before the Due to reordering, push stream data can arrive before the
corresponding PUSH_PROMISE frame. When a client receives a new push corresponding PUSH_PROMISE frame. When a client receives a new push
stream with an as-yet-unknown Push ID, both the associated client stream with an as-yet-unknown push ID, both the associated client
request and the pushed request header fields are unknown. The client request and the pushed request header fields are unknown. The client
can buffer the stream data in expectation of the matching can buffer the stream data in expectation of the matching
PUSH_PROMISE. The client can use stream flow control (see PUSH_PROMISE. The client can use stream flow control (Section 4.1 of
Section 4.1 of [QUIC-TRANSPORT]) to limit the amount of data a server [QUIC-TRANSPORT]) to limit the amount of data a server may commit to
may commit to the pushed stream. the pushed stream. Clients SHOULD abort reading and discard data
already read from push streams if no corresponding PUSH_PROMISE frame
is processed in a reasonable amount of time.
Push stream data can also arrive after a client has canceled a push. Push stream data can also arrive after a client has cancelled a push.
In this case, the client can abort reading the stream with an error In this case, the client can abort reading the stream with an error
code of H3_REQUEST_CANCELLED. This asks the server not to transfer code of H3_REQUEST_CANCELLED. This asks the server not to transfer
additional data and indicates that it will be discarded upon receipt. additional data and indicates that it will be discarded upon receipt.
Pushed responses that are cacheable (see Section 3 of [CACHING]) can Pushed responses that are cacheable (see Section 3 of [HTTP-CACHING])
be stored by the client, if it implements an HTTP cache. Pushed can be stored by the client, if it implements an HTTP cache. Pushed
responses are considered successfully validated on the origin server responses are considered successfully validated on the origin server
(e.g., if the "no-cache" cache response directive is present; see (e.g., if the "no-cache" cache response directive is present; see
Section 5.2.2.3 of [CACHING]) at the time the pushed response is Section 5.2.2.4 of [HTTP-CACHING]) at the time the pushed response is
received. received.
Pushed responses that are not cacheable MUST NOT be stored by any Pushed responses that are not cacheable MUST NOT be stored by any
HTTP cache. They MAY be made available to the application HTTP cache. They MAY be made available to the application
separately. separately.
5. Connection Closure 5. Connection Closure
Once established, an HTTP/3 connection can be used for many requests Once established, an HTTP/3 connection can be used for many requests
and responses over time until the connection is closed. Connection and responses over time until the connection is closed. Connection
closure can happen in any of several different ways. closure can happen in any of several different ways.
5.1. Idle Connections 5.1. Idle Connections
Each QUIC endpoint declares an idle timeout during the handshake. If Each QUIC endpoint declares an idle timeout during the handshake. If
the QUIC connection remains idle (no packets received) for longer the QUIC connection remains idle (no packets received) for longer
than this duration, the peer will assume that the connection has been than this duration, the peer will assume that the connection has been
closed. HTTP/3 implementations will need to open a new HTTP/3 closed. HTTP/3 implementations will need to open a new HTTP/3
connection for new requests if the existing connection has been idle connection for new requests if the existing connection has been idle
for longer than the idle timeout negotiated during the QUIC for longer than the idle timeout negotiated during the QUIC
handshake, and SHOULD do so if approaching the idle timeout; see handshake, and they SHOULD do so if approaching the idle timeout; see
Section 10.1 of [QUIC-TRANSPORT]. Section 10.1 of [QUIC-TRANSPORT].
HTTP clients are expected to request that the transport keep HTTP clients are expected to request that the transport keep
connections open while there are responses outstanding for requests connections open while there are responses outstanding for requests
or server pushes, as described in Section 10.1.2 of [QUIC-TRANSPORT]. or server pushes, as described in Section 10.1.2 of [QUIC-TRANSPORT].
If the client is not expecting a response from the server, allowing If the client is not expecting a response from the server, allowing
an idle connection to time out is preferred over expending effort an idle connection to time out is preferred over expending effort
maintaining a connection that might not be needed. A gateway MAY maintaining a connection that might not be needed. A gateway MAY
maintain connections in anticipation of need rather than incur the maintain connections in anticipation of need rather than incur the
latency cost of connection establishment to servers. Servers SHOULD latency cost of connection establishment to servers. Servers SHOULD
NOT actively keep connections open. NOT actively keep connections open.
5.2. Connection Shutdown 5.2. Connection Shutdown
Even when a connection is not idle, either endpoint can decide to Even when a connection is not idle, either endpoint can decide to
stop using the connection and initiate a graceful connection close. stop using the connection and initiate a graceful connection close.
Endpoints initiate the graceful shutdown of an HTTP/3 connection by Endpoints initiate the graceful shutdown of an HTTP/3 connection by
sending a GOAWAY frame (Section 7.2.6). The GOAWAY frame contains an sending a GOAWAY frame. The GOAWAY frame contains an identifier that
identifier that indicates to the receiver the range of requests or indicates to the receiver the range of requests or pushes that were
pushes that were or might be processed in this connection. The or might be processed in this connection. The server sends a client-
server sends a client-initiated bidirectional Stream ID; the client initiated bidirectional stream ID; the client sends a push ID.
sends a Push ID (Section 4.4). Requests or pushes with the indicated Requests or pushes with the indicated identifier or greater are
identifier or greater are rejected (Section 4.1.2) by the sender of rejected (Section 4.1.1) by the sender of the GOAWAY. This
the GOAWAY. This identifier MAY be zero if no requests or pushes identifier MAY be zero if no requests or pushes were processed.
were processed.
The information in the GOAWAY frame enables a client and server to The information in the GOAWAY frame enables a client and server to
agree on which requests or pushes were accepted prior to the shutdown agree on which requests or pushes were accepted prior to the shutdown
of the HTTP/3 connection. Upon sending a GOAWAY frame, the endpoint of the HTTP/3 connection. Upon sending a GOAWAY frame, the endpoint
SHOULD explicitly cancel (see Section 4.1.2 and Section 7.2.3) any SHOULD explicitly cancel (see Sections 4.1.1 and 7.2.3) any requests
requests or pushes that have identifiers greater than or equal to or pushes that have identifiers greater than or equal to the one
that indicated, in order to clean up transport state for the affected indicated, in order to clean up transport state for the affected
streams. The endpoint SHOULD continue to do so as more requests or streams. The endpoint SHOULD continue to do so as more requests or
pushes arrive. pushes arrive.
Endpoints MUST NOT initiate new requests or promise new pushes on the Endpoints MUST NOT initiate new requests or promise new pushes on the
connection after receipt of a GOAWAY frame from the peer. Clients connection after receipt of a GOAWAY frame from the peer. Clients
MAY establish a new connection to send additional requests. MAY establish a new connection to send additional requests.
Some requests or pushes might already be in transit: Some requests or pushes might already be in transit:
* Upon receipt of a GOAWAY frame, if the client has already sent * Upon receipt of a GOAWAY frame, if the client has already sent
requests with a Stream ID greater than or equal to the identifier requests with a stream ID greater than or equal to the identifier
contained in the GOAWAY frame, those requests will not be contained in the GOAWAY frame, those requests will not be
processed. Clients can safely retry unprocessed requests on a processed. Clients can safely retry unprocessed requests on a
different HTTP connection. A client that is unable to retry different HTTP connection. A client that is unable to retry
requests loses all requests that are in flight when the server requests loses all requests that are in flight when the server
closes the connection. closes the connection.
Requests on Stream IDs less than the Stream ID in a GOAWAY frame Requests on stream IDs less than the stream ID in a GOAWAY frame
from the server might have been processed; their status cannot be from the server might have been processed; their status cannot be
known until a response is received, the stream is reset known until a response is received, the stream is reset
individually, another GOAWAY is received with a lower Stream ID individually, another GOAWAY is received with a lower stream ID
than that of the request in question, or the connection than that of the request in question, or the connection
terminates. terminates.
Servers MAY reject individual requests on streams below the Servers MAY reject individual requests on streams below the
indicated ID if these requests were not processed. indicated ID if these requests were not processed.
* If a server receives a GOAWAY frame after having promised pushes * If a server receives a GOAWAY frame after having promised pushes
with a Push ID greater than or equal to the identifier contained with a push ID greater than or equal to the identifier contained
in the GOAWAY frame, those pushes will not be accepted. in the GOAWAY frame, those pushes will not be accepted.
Servers SHOULD send a GOAWAY frame when the closing of a connection Servers SHOULD send a GOAWAY frame when the closing of a connection
is known in advance, even if the advance notice is small, so that the is known in advance, even if the advance notice is small, so that the
remote peer can know whether a request has been partially processed remote peer can know whether or not a request has been partially
or not. For example, if an HTTP client sends a POST at the same time processed. For example, if an HTTP client sends a POST at the same
that a server closes a QUIC connection, the client cannot know if the time that a server closes a QUIC connection, the client cannot know
server started to process that POST request if the server does not if the server started to process that POST request if the server does
send a GOAWAY frame to indicate what streams it might have acted on. not send a GOAWAY frame to indicate what streams it might have acted
on.
An endpoint MAY send multiple GOAWAY frames indicating different An endpoint MAY send multiple GOAWAY frames indicating different
identifiers, but the identifier in each frame MUST NOT be greater identifiers, but the identifier in each frame MUST NOT be greater
than the identifier in any previous frame, since clients might than the identifier in any previous frame, since clients might
already have retried unprocessed requests on another HTTP connection. already have retried unprocessed requests on another HTTP connection.
Receiving a GOAWAY containing a larger identifier than previously Receiving a GOAWAY containing a larger identifier than previously
received MUST be treated as a connection error of type H3_ID_ERROR; received MUST be treated as a connection error of type H3_ID_ERROR.
see Section 8.
An endpoint that is attempting to gracefully shut down a connection An endpoint that is attempting to gracefully shut down a connection
can send a GOAWAY frame with a value set to the maximum possible can send a GOAWAY frame with a value set to the maximum possible
value (2^(62)-4 for servers, 2^(62)-1 for clients). This ensures value (2^62-4 for servers, 2^62-1 for clients). This ensures that
that the peer stops creating new requests or pushes. After allowing the peer stops creating new requests or pushes. After allowing time
time for any in-flight requests or pushes to arrive, the endpoint can for any in-flight requests or pushes to arrive, the endpoint can send
send another GOAWAY frame indicating which requests or pushes it another GOAWAY frame indicating which requests or pushes it might
might accept before the end of the connection. This ensures that a accept before the end of the connection. This ensures that a
connection can be cleanly shut down without losing requests. connection can be cleanly shut down without losing requests.
A client has more flexibility in the value it chooses for the Push ID A client has more flexibility in the value it chooses for the Push ID
in a GOAWAY that it sends. A value of 2^(62)-1 indicates that the field in a GOAWAY that it sends. A value of 2^62-1 indicates that
server can continue fulfilling pushes that have already been the server can continue fulfilling pushes that have already been
promised. A smaller value indicates the client will reject pushes promised. A smaller value indicates the client will reject pushes
with Push IDs greater than or equal to this value. Like the server, with push IDs greater than or equal to this value. Like the server,
the client MAY send subsequent GOAWAY frames so long as the specified the client MAY send subsequent GOAWAY frames so long as the specified
Push ID is no greater than any previously sent value. push ID is no greater than any previously sent value.
Even when a GOAWAY indicates that a given request or push will not be Even when a GOAWAY indicates that a given request or push will not be
processed or accepted upon receipt, the underlying transport processed or accepted upon receipt, the underlying transport
resources still exist. The endpoint that initiated these requests resources still exist. The endpoint that initiated these requests
can cancel them to clean up transport state. can cancel them to clean up transport state.
Once all accepted requests and pushes have been processed, the Once all accepted requests and pushes have been processed, the
endpoint can permit the connection to become idle, or MAY initiate an endpoint can permit the connection to become idle, or it MAY initiate
immediate closure of the connection. An endpoint that completes a an immediate closure of the connection. An endpoint that completes a
graceful shutdown SHOULD use the H3_NO_ERROR error code when closing graceful shutdown SHOULD use the H3_NO_ERROR error code when closing
the connection. the connection.
If a client has consumed all available bidirectional stream IDs with If a client has consumed all available bidirectional stream IDs with
requests, the server need not send a GOAWAY frame, since the client requests, the server need not send a GOAWAY frame, since the client
is unable to make further requests. is unable to make further requests.
5.3. Immediate Application Closure 5.3. Immediate Application Closure
An HTTP/3 implementation can immediately close the QUIC connection at An HTTP/3 implementation can immediately close the QUIC connection at
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A QUIC stream provides reliable in-order delivery of bytes, but makes A QUIC stream provides reliable in-order delivery of bytes, but makes
no guarantees about order of delivery with regard to bytes on other no guarantees about order of delivery with regard to bytes on other
streams. In version 1 of QUIC, the stream data containing HTTP streams. In version 1 of QUIC, the stream data containing HTTP
frames is carried by QUIC STREAM frames, but this framing is frames is carried by QUIC STREAM frames, but this framing is
invisible to the HTTP framing layer. The transport layer buffers and invisible to the HTTP framing layer. The transport layer buffers and
orders received stream data, exposing a reliable byte stream to the orders received stream data, exposing a reliable byte stream to the
application. Although QUIC permits out-of-order delivery within a application. Although QUIC permits out-of-order delivery within a
stream, HTTP/3 does not make use of this feature. stream, HTTP/3 does not make use of this feature.
QUIC streams can be either unidirectional, carrying data only from QUIC streams can be either unidirectional, carrying data only from
initiator to receiver, or bidirectional. Streams can be initiated by initiator to receiver, or bidirectional, carrying data in both
either the client or the server. For more detail on QUIC streams, directions. Streams can be initiated by either the client or the
see Section 2 of [QUIC-TRANSPORT]. server. For more detail on QUIC streams, see Section 2 of
[QUIC-TRANSPORT].
When HTTP fields and data are sent over QUIC, the QUIC layer handles When HTTP fields and data are sent over QUIC, the QUIC layer handles
most of the stream management. HTTP does not need to do any separate most of the stream management. HTTP does not need to do any separate
multiplexing when using QUIC - data sent over a QUIC stream always multiplexing when using QUIC: data sent over a QUIC stream always
maps to a particular HTTP transaction or to the entire HTTP/3 maps to a particular HTTP transaction or to the entire HTTP/3
connection context. 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. These streams are referred be readily correlated with the request. These streams are referred
to as request streams. to as request streams.
This means that the client's first request occurs on QUIC stream 0, This means that the client's first request occurs on QUIC stream 0,
with subsequent requests on stream 4, 8, and so on. In order to with subsequent requests on streams 4, 8, and so on. In order to
permit these streams to open, an HTTP/3 server SHOULD configure non- permit these streams to open, an HTTP/3 server SHOULD configure non-
zero minimum values for the number of permitted streams and the zero minimum values for the number of permitted streams and the
initial stream flow control window. So as to not unnecessarily limit initial stream flow-control window. So as to not unnecessarily limit
parallelism, at least 100 request streams SHOULD be permitted at a parallelism, at least 100 request streams SHOULD be permitted at a
time. time.
HTTP/3 does not use server-initiated bidirectional streams, though an HTTP/3 does not use server-initiated bidirectional streams, though an
extension could define a use for these streams. Clients MUST treat extension could define a use for these streams. Clients MUST treat
receipt of a server-initiated bidirectional stream as a connection receipt of a server-initiated bidirectional stream as a connection
error of type H3_STREAM_CREATION_ERROR (Section 8) unless such an error of type H3_STREAM_CREATION_ERROR unless such an extension has
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
purposes. The purpose is indicated by a stream type, which is sent purposes. The purpose is indicated by a stream type, which is sent
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.
Unidirectional Stream Header { Unidirectional Stream Header {
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Two stream types are defined in this document: control streams Two stream types are defined in this document: control streams
(Section 6.2.1) and push streams (Section 6.2.2). [QPACK] defines (Section 6.2.1) and push streams (Section 6.2.2). [QPACK] defines
two additional stream types. Other stream types can be defined by two additional stream types. Other stream types can be defined by
extensions to HTTP/3; see Section 9 for more details. Some stream extensions to HTTP/3; see Section 9 for more details. Some stream
types are reserved (Section 6.2.3). types are reserved (Section 6.2.3).
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 excessively restrict the unidirectional streams. Endpoints that excessively restrict the
number of streams or the flow control window of these streams will number of streams or the flow-control window of these streams will
increase the chance that the remote peer reaches the limit early and increase the chance that the remote peer reaches the limit early and
becomes blocked. In particular, implementations should consider that becomes blocked. In particular, implementations should consider that
remote peers may wish to exercise reserved stream behavior remote peers may wish to exercise reserved stream behavior
(Section 6.2.3) with some of the unidirectional streams they are (Section 6.2.3) with some of the unidirectional streams they are
permitted to use. To avoid blocking, the transport parameters sent permitted to use.
by both clients and servers MUST allow the peer to create at least
one unidirectional stream for the HTTP control stream plus the number Each endpoint needs to create at least one unidirectional stream for
of unidirectional streams required by mandatory extensions (three the HTTP control stream. QPACK requires two additional
being the minimum number required for the base HTTP/3 protocol and unidirectional streams, and other extensions might require further
QPACK), and SHOULD provide at least 1,024 bytes of flow control streams. Therefore, the transport parameters sent by both clients
credit to each stream. and servers MUST allow the peer to create at least three
unidirectional streams. These transport parameters SHOULD also
provide at least 1,024 bytes of flow-control credit to each
unidirectional stream.
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 that is not supported by If the stream header indicates a stream type that is not supported by
the recipient, the remainder of the stream cannot be consumed as the the recipient, the remainder of the stream cannot be consumed as the
semantics are unknown. Recipients of unknown stream types MAY abort semantics are unknown. Recipients of unknown stream types MUST
reading of the stream with an error code of H3_STREAM_CREATION_ERROR either abort reading of the stream or discard incoming data without
or a reserved error code (Section 8.1), but MUST NOT consider such further processing. If reading is aborted, the recipient SHOULD use
streams to be a connection error of any kind. the H3_STREAM_CREATION_ERROR error code or a reserved error code
(Section 8.1). The recipient MUST NOT consider unknown stream types
to be a connection error of any kind.
As certain stream types can affect connection state, a recipient
SHOULD NOT discard data from incoming unidirectional streams prior to
reading the stream type.
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 that could modify the state or supports them. However, stream types that 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
closed or reset prior to the reception of the unidirectional stream closed or reset prior to the reception of the unidirectional stream
header. header.
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H3_MISSING_SETTINGS. Only one control stream per peer is permitted; H3_MISSING_SETTINGS. Only one control stream per peer is permitted;
receipt of a second stream claiming to be a control stream MUST be receipt of a second stream claiming to be a control stream MUST be
treated as a connection error of type H3_STREAM_CREATION_ERROR. The treated as a connection error of type H3_STREAM_CREATION_ERROR. The
sender MUST NOT close the control stream, and the receiver MUST NOT sender MUST NOT close the control stream, and the receiver MUST NOT
request that the sender close the control stream. If either control request that the sender close the control stream. If either control
stream is closed at any point, this MUST be treated as a connection stream is closed at any point, this MUST be treated as a connection
error of type H3_CLOSED_CRITICAL_STREAM. Connection errors are error of type H3_CLOSED_CRITICAL_STREAM. Connection errors are
described in Section 8. described in Section 8.
Because the contents of the control stream are used to manage the Because the contents of the control stream are used to manage the
behavior of other streams, endpoints SHOULD provide enough flow behavior of other streams, endpoints SHOULD provide enough flow-
control credit to keep the peer's control stream from becoming control credit to keep the peer's control stream from becoming
blocked. blocked.
A pair of unidirectional streams is used rather than a single A pair of unidirectional streams is used rather than a single
bidirectional stream. This allows either peer to send data as soon bidirectional stream. This allows either peer to send data as soon
as it is able. Depending on whether 0-RTT is available on the QUIC as it is able. Depending on whether 0-RTT is available on the QUIC
connection, either client or server might be able to send stream data connection, either client or server might be able to send stream data
first. first.
6.2.2. Push Streams 6.2.2. Push Streams
Server push is an optional feature introduced in HTTP/2 that allows a Server push is an optional feature introduced in HTTP/2 that allows a
server to initiate a response before a request has been made. See server to initiate a response before a request has been made. See
Section 4.4 for more details. Section 4.6 for more details.
A push stream is indicated by a stream type of 0x01, followed by the A push stream is indicated by a stream type of 0x01, followed by the
Push ID of the promise that it fulfills, encoded as a variable-length push ID of the promise that it fulfills, encoded as a variable-length
integer. The remaining data on this stream consists of HTTP/3 integer. The remaining data on this stream consists of HTTP/3
frames, as defined in Section 7.2, and fulfills a promised server frames, as defined in Section 7.2, and fulfills a promised server
push by zero or more interim HTTP responses followed by a single push by zero or more interim HTTP responses followed by a single
final HTTP response, as defined in Section 4.1. Server push and Push final HTTP response, as defined in Section 4.1. Server push and push
IDs are described in Section 4.4. IDs are described in Section 4.6.
Only servers can push; if a server receives a client-initiated push Only servers can push; if a server receives a client-initiated push
stream, this MUST be treated as a connection error of type stream, this MUST be treated as a connection error of type
H3_STREAM_CREATION_ERROR; see Section 8. H3_STREAM_CREATION_ERROR.
Push Stream Header { Push Stream Header {
Stream Type (i) = 0x01, Stream Type (i) = 0x01,
Push ID (i), Push ID (i),
} }
Figure 2: Push Stream Header Figure 2: Push Stream Header
Each Push ID MUST only be used once in a push stream header. If a A client SHOULD NOT abort reading on a push stream prior to reading
push stream header includes a Push ID that was used in another push the push stream header, as this could lead to disagreement between
stream header, the client MUST treat this as a connection error of client and server on which push IDs have already been consumed.
type H3_ID_ERROR; see Section 8.
Each push ID MUST only be used once in a push stream header. If a
client detects that a 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 type H3_ID_ERROR.
6.2.3. Reserved Stream Types 6.2.3. Reserved Stream Types
Stream types of the format "0x1f * N + 0x21" for non-negative integer Stream types of the format 0x1f * N + 0x21 for non-negative integer
values of N are reserved to exercise the requirement that unknown values of N are reserved to exercise the requirement that unknown
types be ignored. These streams have no semantics, and can be sent types be ignored. These streams have no semantics, and they can be
when application-layer padding is desired. They MAY also be sent on sent when application-layer padding is desired. They MAY also be
connections where no data is currently being transferred. Endpoints sent on connections where no data is currently being transferred.
MUST NOT consider these streams to have any meaning upon receipt. Endpoints MUST NOT consider these streams to have any meaning upon
receipt.
The payload and length of the stream are selected in any manner the The payload and length of the stream are selected in any manner the
sending implementation chooses. When sending a reserved stream type, sending implementation chooses. When sending a reserved stream type,
the implementation MAY either terminate the stream cleanly or reset the implementation MAY either terminate the stream cleanly or reset
it. When resetting the stream, either the H3_NO_ERROR error code or it. When resetting the stream, either the H3_NO_ERROR error code or
a reserved error code (Section 8.1) SHOULD be used. a reserved error code (Section 8.1) SHOULD be used.
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.
skipping to change at page 32, line 31 skipping to change at line 1440
Length: A variable-length integer that describes the length in bytes Length: A variable-length integer that describes the length in bytes
of the Frame Payload. of the Frame Payload.
Frame Payload: A payload, the semantics of which are determined by Frame Payload: A payload, the semantics of which are determined by
the Type field. the Type field.
Each frame's payload MUST contain exactly the fields identified in Each frame's payload MUST contain exactly the fields identified in
its description. A frame payload that contains additional bytes its description. A frame payload that contains additional bytes
after the identified fields or a frame payload that terminates before after the identified fields or a frame payload that terminates before
the end of the identified fields MUST be treated as a connection the end of the identified fields MUST be treated as a connection
error of type H3_FRAME_ERROR; see Section 8. In particular, error of type H3_FRAME_ERROR. In particular, redundant length
redundant length encodings MUST be verified to be self-consistent; encodings MUST be verified to be self-consistent; see Section 10.8.
see Section 10.8.
When a stream terminates cleanly, if the last frame on the stream was When a stream terminates cleanly, if the last frame on the stream was
truncated, this MUST be treated as a connection error of type truncated, this MUST be treated as a connection error of type
H3_FRAME_ERROR; see Section 8. Streams that terminate abruptly may H3_FRAME_ERROR. Streams that terminate abruptly may be reset at any
be reset at any point in a frame. 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=0x00) convey arbitrary, variable-length sequences
bytes associated with HTTP request or response content. of bytes associated with HTTP request or response content.
DATA frames MUST be associated with an HTTP request or response. If DATA frames MUST be associated with an HTTP request or response. If
a DATA frame is received on a control stream, the recipient MUST a DATA frame is received on a control stream, the recipient MUST
respond with a connection error of type H3_FRAME_UNEXPECTED; see respond with a connection error of type H3_FRAME_UNEXPECTED.
Section 8.
DATA Frame { DATA Frame {
Type (i) = 0x0, Type (i) = 0x00,
Length (i), Length (i),
Data (..), Data (..),
} }
Figure 4: DATA Frame Figure 4: DATA Frame
7.2.2. HEADERS 7.2.2. HEADERS
The HEADERS frame (type=0x1) is used to carry an HTTP field section, The HEADERS frame (type=0x01) is used to carry an HTTP field section
encoded using QPACK. See [QPACK] for more details. that is encoded using QPACK. See [QPACK] for more details.
HEADERS Frame { HEADERS Frame {
Type (i) = 0x1, Type (i) = 0x01,
Length (i), Length (i),
Encoded Field Section (..), Encoded Field Section (..),
} }
Figure 5: HEADERS Frame Figure 5: HEADERS Frame
HEADERS frames can only be sent on request or push streams. If a HEADERS frames can only be sent on request streams or push streams.
HEADERS frame is received on a control stream, the recipient MUST If a HEADERS frame is received on a control stream, the recipient
respond with a connection error (Section 8) of type MUST respond with a connection error of type H3_FRAME_UNEXPECTED.
H3_FRAME_UNEXPECTED.
7.2.3. 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=0x03) is used to request cancellation of
server push prior to the push stream being received. The CANCEL_PUSH a server push prior to the push stream being received. The
frame identifies a server push by Push ID (see Section 4.4), encoded CANCEL_PUSH frame identifies a server push by push ID (see
as a variable-length integer. Section 4.6), encoded as a variable-length integer.
When a client sends CANCEL_PUSH, it is indicating that it does not When a client sends a CANCEL_PUSH frame, it is indicating that it
wish to receive the promised resource. The server SHOULD abort does not wish to receive the promised resource. The server SHOULD
sending the resource, but the mechanism to do so depends on the state abort sending the resource, but the mechanism to do so depends on the
of the corresponding push stream. If the server has not yet created state of the corresponding push stream. If the server has not yet
a push stream, it does not create one. If the push stream is open, created a push stream, it does not create one. If the push stream is
the server SHOULD abruptly terminate that stream. If the push stream open, the server SHOULD abruptly terminate that stream. If the push
has already ended, the server MAY still abruptly terminate the stream stream has already ended, the server MAY still abruptly terminate the
or MAY take no action. stream or MAY take no action.
A server sends CANCEL_PUSH to indicate that it will not be fulfilling A server sends a CANCEL_PUSH frame to indicate that it will not be
a promise which was previously sent. The client cannot expect the fulfilling a promise that was previously sent. The client cannot
corresponding promise to be fulfilled, unless it has already received expect the corresponding promise to be fulfilled, unless it has
and processed the promised response. Regardless of whether a push already received and processed the promised response. Regardless of
stream has been opened, a server SHOULD send a CANCEL_PUSH frame when whether a push stream has been opened, a server SHOULD send a
it determines that promise will not be fulfilled. If a stream has CANCEL_PUSH frame when it determines that promise will not be
already been opened, the server can abort sending on the stream with fulfilled. If a stream has already been opened, the server can abort
an error code of H3_REQUEST_CANCELLED. sending on the stream with an error code of H3_REQUEST_CANCELLED.
Sending a CANCEL_PUSH frame has no direct effect on the state of Sending a CANCEL_PUSH frame has no direct effect on the state of
existing push streams. A client SHOULD NOT send a CANCEL_PUSH frame existing push streams. A client SHOULD NOT send a CANCEL_PUSH frame
when it has already received a corresponding push stream. A push when it has already received a corresponding push stream. A push
stream could arrive after a client has sent a CANCEL_PUSH frame, stream could arrive after a client has sent a CANCEL_PUSH frame,
because a server might not have processed the CANCEL_PUSH. The because a server might not have processed the CANCEL_PUSH. The
client SHOULD abort reading the stream with an error code of client SHOULD abort reading the stream with an error code of
H3_REQUEST_CANCELLED. H3_REQUEST_CANCELLED.
A CANCEL_PUSH frame is sent on the control stream. Receiving a A CANCEL_PUSH frame is sent on the control stream. Receiving a
CANCEL_PUSH frame on a stream other than the control stream MUST be CANCEL_PUSH frame on a stream other than the control stream MUST be
treated as a connection error of type H3_FRAME_UNEXPECTED. treated as a connection error of type H3_FRAME_UNEXPECTED.
CANCEL_PUSH Frame { CANCEL_PUSH Frame {
Type (i) = 0x3, Type (i) = 0x03,
Length (i), Length (i),
Push ID (i), Push ID (i),
} }
Figure 6: CANCEL_PUSH Frame Figure 6: CANCEL_PUSH Frame
The CANCEL_PUSH frame carries a Push ID encoded as a variable-length The CANCEL_PUSH frame carries a push ID encoded as a variable-length
integer. The Push ID identifies the server push that is being integer. The Push ID field identifies the server push that is being
cancelled; see Section 4.4. If a CANCEL_PUSH frame is received that cancelled; see Section 4.6. If a CANCEL_PUSH frame is received that
references a Push ID greater than currently allowed on the references a push ID greater than currently allowed on the
connection, this MUST be treated as a connection error of type connection, this MUST be treated as a connection error of type
H3_ID_ERROR. H3_ID_ERROR.
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 due a push ID that has not yet been mentioned by a PUSH_PROMISE frame due
to reordering. If a server receives a CANCEL_PUSH frame for a Push to reordering. If a server receives a CANCEL_PUSH frame for a push
ID that has not yet been mentioned by a PUSH_PROMISE frame, this MUST ID that has not yet been mentioned by a PUSH_PROMISE frame, this MUST
be treated as a connection error of type H3_ID_ERROR. be treated as a connection error of type H3_ID_ERROR.
7.2.4. SETTINGS 7.2.4. SETTINGS
The SETTINGS frame (type=0x4) conveys configuration parameters that The SETTINGS frame (type=0x04) 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 an entire HTTP/3 connection, never a SETTINGS frames always apply to an entire HTTP/3 connection, never a
single stream. A SETTINGS frame MUST be sent as the first frame of single stream. 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 each control stream (see Section 6.2.1) by each peer, and it MUST NOT
sent subsequently. If an endpoint receives a second SETTINGS frame be sent subsequently. If an endpoint receives a second SETTINGS
on the control stream, the endpoint MUST respond with a connection frame on the control stream, the endpoint MUST respond with a
error of type H3_FRAME_UNEXPECTED. connection error of type H3_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
H3_FRAME_UNEXPECTED. H3_FRAME_UNEXPECTED.
SETTINGS parameters are not negotiated; they describe characteristics SETTINGS parameters are not negotiated; they describe characteristics
of the sending peer that can be used by the receiving peer. However, of the sending peer that can be used by the receiving peer. However,
a negotiation can be implied by the use of SETTINGS - each peer uses a negotiation can be implied by the use of SETTINGS: each peer uses
SETTINGS to advertise a set of supported values. The definition of SETTINGS to advertise a set of supported values. The definition of
the setting would describe how each peer combines the two sets to the setting would describe how each peer combines the two sets to
conclude which choice will be used. SETTINGS does not provide a conclude which choice will be used. SETTINGS does not provide a
mechanism to identify when the choice takes effect. 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 field section, while servers are more cautious about request response field section, while servers are more cautious about request
size. size.
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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.
Setting { Setting {
Identifier (i), Identifier (i),
Value (i), Value (i),
} }
SETTINGS Frame { SETTINGS Frame {
Type (i) = 0x4, Type (i) = 0x04,
Length (i), Length (i),
Setting (..) ..., Setting (..) ...,
} }
Figure 7: SETTINGS Frame Figure 7: SETTINGS Frame
An implementation MUST ignore any parameter with an identifier it An implementation MUST ignore any parameter with an identifier it
does not understand. does not understand.
7.2.4.1. Defined SETTINGS Parameters 7.2.4.1. Defined SETTINGS Parameters
The following settings are defined in HTTP/3: The following settings are defined in HTTP/3:
SETTINGS_MAX_FIELD_SECTION_SIZE (0x6): The default value is SETTINGS_MAX_FIELD_SECTION_SIZE (0x06): The default value is
unlimited. See Section 4.1.1.3 for usage. unlimited. See Section 4.2.2 for usage.
Setting identifiers of the format "0x1f * N + 0x21" for non-negative Setting identifiers of the format 0x1f * N + 0x21 for non-negative
integer values of N are reserved to exercise the requirement that integer values of N are reserved to exercise the requirement that
unknown identifiers be ignored. Such settings have no defined unknown identifiers be ignored. Such settings have no defined
meaning. Endpoints SHOULD include at least one such setting in their meaning. Endpoints SHOULD include at least one such setting in their
SETTINGS frame. Endpoints MUST NOT consider such settings to have SETTINGS frame. Endpoints MUST NOT consider such settings to have
any meaning upon receipt. any meaning upon receipt.
Because the setting has no defined meaning, the value of the setting Because the setting has no defined meaning, the value of the setting
can be any value the implementation selects. can be any value the implementation selects.
Setting identifiers which were defined in [HTTP2] where there is no Setting identifiers that were defined in [HTTP/2] where there is no
corresponding HTTP/3 setting have also been reserved corresponding HTTP/3 setting have also been reserved
(Section 11.2.2). These reserved settings MUST NOT be sent, and (Section 11.2.2). These reserved settings MUST NOT be sent, and
their receipt MUST be treated as a connection error of type their receipt MUST be treated as a connection error of type
H3_SETTINGS_ERROR. H3_SETTINGS_ERROR.
Additional settings can be defined by extensions to HTTP/3; see Additional settings can be defined by extensions to HTTP/3; see
Section 9 for more details. Section 9 for more details.
7.2.4.2. Initialization 7.2.4.2. Initialization
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as soon as the transport is ready to send data. as soon as the transport is ready to send data.
For servers, the initial value of each client setting is the default For servers, the initial value of each client setting is the default
value. 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. 1-RTT keys will always become server setting is the default value. 1-RTT keys will always become
available prior to the packet containing SETTINGS being processed by available prior to the packet containing SETTINGS being processed by
QUIC, even if the server sends SETTINGS immediately. Clients SHOULD QUIC, even if the server sends SETTINGS immediately. Clients SHOULD
NOT wait indefinitely for SETTINGS to arrive before sending requests, NOT wait indefinitely for SETTINGS to arrive before sending requests,
but SHOULD process received datagrams in order to increase the but they SHOULD process received datagrams in order to increase the
likelihood of processing SETTINGS before sending the first request. likelihood of processing SETTINGS before sending the first request.
When a 0-RTT QUIC connection is being used, the initial value of each 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 server setting is the value used in the previous session. Clients
SHOULD store the settings the server provided in the HTTP/3 SHOULD store the settings the server provided in the HTTP/3
connection where resumption information was provided, but MAY opt not connection where resumption information was provided, but they MAY
to store settings in certain cases (e.g., if the session ticket is opt not to store settings in certain cases (e.g., if the session
received before the SETTINGS frame). A client MUST comply with ticket is received before the SETTINGS frame). A client MUST comply
stored settings -- or default values, if no values are stored -- when with stored settings -- or default values if no values are stored --
attempting 0-RTT. Once a server has provided new settings, clients when attempting 0-RTT. Once a server has provided new settings,
MUST comply with those values. 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. If the settings values in determining whether to accept 0-RTT data. If the
server cannot determine that the settings remembered by a client are server cannot determine that the settings remembered by a client are
compatible with its current settings, it MUST NOT accept 0-RTT data. compatible with its current settings, it MUST NOT accept 0-RTT data.
Remembered settings are compatible if a client complying with those Remembered settings are compatible if a client complying with those
settings would not violate the server's current settings. 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
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server accepts 0-RTT but then sends settings that are not compatible server accepts 0-RTT but then sends settings that are not compatible
with the previously specified settings, this MUST be treated as a with the previously specified settings, this MUST be treated as a
connection error of type H3_SETTINGS_ERROR. If a server accepts connection error of type H3_SETTINGS_ERROR. If a server accepts
0-RTT but then sends a SETTINGS frame that omits a setting value that 0-RTT but then sends a SETTINGS frame that omits a setting value that
the client understands (apart from reserved setting identifiers) that the client understands (apart from reserved setting identifiers) that
was previously specified to have a non-default value, this MUST be was previously specified to have a non-default value, this MUST be
treated as a connection error of type H3_SETTINGS_ERROR. treated as a connection error of type H3_SETTINGS_ERROR.
7.2.5. PUSH_PROMISE 7.2.5. PUSH_PROMISE
The PUSH_PROMISE frame (type=0x5) is used to carry a promised request The PUSH_PROMISE frame (type=0x05) is used to carry a promised
header section from server to client on a request stream, as in request header section from server to client on a request stream.
HTTP/2.
PUSH_PROMISE Frame { PUSH_PROMISE Frame {
Type (i) = 0x5, Type (i) = 0x05,
Length (i), Length (i),
Push ID (i), Push ID (i),
Encoded Field Section (..), Encoded Field Section (..),
} }
Figure 8: PUSH_PROMISE Frame Figure 8: PUSH_PROMISE Frame
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 (Section 4.4) operation. A push ID is used in push stream headers (Section 4.6)
and CANCEL_PUSH frames (Section 7.2.3). and CANCEL_PUSH frames.
Encoded Field Section: QPACK-encoded request header fields for the Encoded Field Section: QPACK-encoded request header fields for the
promised response. See [QPACK] for more details. promised response. See [QPACK] for more details.
A server MUST NOT use a Push ID that is larger than the client has A server MUST NOT use a push ID that is larger than the client has
provided in a MAX_PUSH_ID frame (Section 7.2.7). A client MUST treat provided in a MAX_PUSH_ID frame (Section 7.2.7). A client MUST treat
receipt of a PUSH_PROMISE frame that contains a larger Push ID than receipt of a PUSH_PROMISE frame that contains a larger push ID than
the client has advertised as a connection error of H3_ID_ERROR. the client has advertised as a connection error of H3_ID_ERROR.
A server MAY use the same Push ID in multiple PUSH_PROMISE frames. A server MAY use the same push ID in multiple PUSH_PROMISE frames.
If so, the decompressed request header sets MUST contain the same If so, the decompressed request header sets MUST contain the same
fields in the same order, and both the name and the value in each fields in the same order, and both the name and the value in each
field MUST be exact matches. Clients SHOULD compare the request field MUST be exact matches. Clients SHOULD compare the request
header sections for resources promised multiple times. If a client header sections for resources promised multiple times. If a client
receives a Push ID that has already been promised and detects a receives a push ID that has already been promised and detects a
mismatch, it MUST respond with a connection error of type mismatch, it MUST respond with a connection error of type
H3_GENERAL_PROTOCOL_ERROR. If the decompressed field sections match H3_GENERAL_PROTOCOL_ERROR. If the decompressed field sections match
exactly, the client SHOULD associate the pushed content with each exactly, the client SHOULD associate the pushed content with each
stream on which a PUSH_PROMISE frame was received. stream on which a PUSH_PROMISE frame was received.
Allowing duplicate references to the same Push ID is primarily to Allowing duplicate references to the same push ID is primarily to
reduce duplication caused by concurrent requests. A server SHOULD reduce duplication caused by concurrent requests. A server SHOULD
avoid reusing a Push ID over a long period. Clients are likely to avoid reusing a push ID over a long period. Clients are likely to
consume server push responses and not retain them for reuse over consume server push responses and not retain them for reuse over
time. Clients that see a PUSH_PROMISE frame that uses a Push ID that time. Clients that see a PUSH_PROMISE frame that uses a push ID that
they have already consumed and discarded are forced to ignore the they have already consumed and discarded are forced to ignore the
promise. promise.
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 of type H3_FRAME_UNEXPECTED; see MUST respond with a connection error of type H3_FRAME_UNEXPECTED.
Section 8.
A client MUST NOT send a PUSH_PROMISE frame. A server MUST treat the A client MUST NOT send a PUSH_PROMISE frame. A server MUST treat the
receipt of a PUSH_PROMISE frame as a connection error of type receipt of a PUSH_PROMISE frame as a connection error of type
H3_FRAME_UNEXPECTED; see Section 8. H3_FRAME_UNEXPECTED.
See Section 4.4 for a description of the overall server push See Section 4.6 for a description of the overall server push
mechanism. mechanism.
7.2.6. GOAWAY 7.2.6. GOAWAY
The GOAWAY frame (type=0x7) is used to initiate graceful shutdown of The GOAWAY frame (type=0x07) is used to initiate graceful shutdown of
an HTTP/3 connection by either endpoint. GOAWAY allows an endpoint an HTTP/3 connection by either endpoint. GOAWAY allows an endpoint
to stop accepting new requests or pushes while still finishing to stop accepting new requests or pushes while still finishing
processing of previously received requests and pushes. This enables processing of previously received requests and pushes. This enables
administrative actions, like server maintenance. GOAWAY by itself administrative actions, like server maintenance. GOAWAY by itself
does not close a connection. does not close a connection.
GOAWAY Frame { GOAWAY Frame {
Type (i) = 0x7, Type (i) = 0x07,
Length (i), Length (i),
Stream ID/Push ID (..), Stream ID/Push ID (i),
} }
Figure 9: GOAWAY Frame Figure 9: GOAWAY Frame
The GOAWAY frame is always sent on the control stream. In the server The GOAWAY frame is always sent on the control stream. In the
to client direction, it carries a QUIC Stream ID for a client- server-to-client direction, it carries a QUIC stream ID for a client-
initiated bidirectional stream encoded as a variable-length integer. initiated bidirectional stream encoded as a variable-length integer.
A client MUST treat receipt of a GOAWAY frame containing a Stream ID A client MUST treat receipt of a GOAWAY frame containing a stream ID
of any other type as a connection error of type H3_ID_ERROR. of any other type as a connection error of type H3_ID_ERROR.
In the client to server direction, the GOAWAY frame carries a Push ID In the client-to-server direction, the GOAWAY frame carries a push ID
encoded as a variable-length integer. encoded as a variable-length integer.
The GOAWAY frame applies to the entire connection, not a specific The GOAWAY frame applies to the entire connection, not a specific
stream. A client MUST treat a GOAWAY frame on a stream other than stream. A client MUST treat a GOAWAY frame on a stream other than
the control stream as a connection error of type H3_FRAME_UNEXPECTED; the control stream as a connection error of type H3_FRAME_UNEXPECTED.
see Section 8.
See Section 5.2 for more information on the use of the GOAWAY frame. See Section 5.2 for more information on the use of the GOAWAY frame.
7.2.7. MAX_PUSH_ID 7.2.7. MAX_PUSH_ID
The MAX_PUSH_ID frame (type=0xd) is used by clients to control the The MAX_PUSH_ID frame (type=0x0d) 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 PUSH_PROMISE maximum value for a push ID that the server can use in PUSH_PROMISE
and CANCEL_PUSH frames. Consequently, this also limits the number of and CANCEL_PUSH frames. Consequently, this also limits the number of
push streams that the server can initiate in addition to the limit push streams that the server can initiate in addition to the limit
maintained by the QUIC transport. maintained by 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 H3_FRAME_UNEXPECTED. connection error of type H3_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
H3_FRAME_UNEXPECTED. H3_FRAME_UNEXPECTED.
The maximum Push ID is unset when an HTTP/3 connection is created, The maximum push ID is unset when an HTTP/3 connection is created,
meaning that a server cannot push until it receives a MAX_PUSH_ID meaning that a server cannot push until it receives a MAX_PUSH_ID
frame. A client that wishes to manage the number of promised server frame. A client that wishes to manage the number of promised server
pushes can increase the maximum Push ID by sending MAX_PUSH_ID frames pushes can increase the maximum push ID by sending MAX_PUSH_ID frames
as the server fulfills or cancels server pushes. as the server fulfills or cancels server pushes.
MAX_PUSH_ID Frame { MAX_PUSH_ID Frame {
Type (i) = 0xd, Type (i) = 0x0d,
Length (i), Length (i),
Push ID (i), Push ID (i),
} }
Figure 10: MAX_PUSH_ID Frame Figure 10: MAX_PUSH_ID Frame
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 4.4. A MAX_PUSH_ID frame cannot reduce the maximum Push see Section 4.6. A MAX_PUSH_ID frame cannot reduce the maximum push
ID; receipt of a MAX_PUSH_ID frame that contains a smaller value than ID; receipt of a MAX_PUSH_ID frame 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
H3_ID_ERROR. H3_ID_ERROR.
7.2.8. Reserved Frame Types 7.2.8. Reserved Frame Types
Frame types of the format "0x1f * N + 0x21" for non-negative integer Frame types of the format 0x1f * N + 0x21 for non-negative integer
values of N are reserved to exercise the requirement that unknown values of N are reserved to exercise the requirement that unknown
types be ignored (Section 9). These frames have no semantics, and types be ignored (Section 9). These frames have no semantics, and
MAY be sent on any stream where frames are allowed to be sent. This they MAY be sent on any stream where frames are allowed to be sent.
enables their use for application-layer padding. Endpoints MUST NOT This enables their use for application-layer padding. Endpoints MUST
consider these frames to have any meaning upon receipt. 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 that were used in HTTP/2 where there is no corresponding Frame types that were used in HTTP/2 where there is no corresponding
HTTP/3 frame have also been reserved (Section 11.2.1). These frame HTTP/3 frame have also been reserved (Section 11.2.1). These frame
types MUST NOT be sent, and their receipt MUST be treated as a types MUST NOT be sent, and their receipt MUST be treated as a
connection error of type H3_FRAME_UNEXPECTED. connection error of type H3_FRAME_UNEXPECTED.
8. Error Handling 8. Error Handling
When a stream cannot be completed successfully, QUIC allows the When a stream cannot be completed successfully, QUIC allows the
application to abruptly terminate (reset) that stream and communicate application to abruptly terminate (reset) that stream and communicate
a reason; see Section 2.4 of [QUIC-TRANSPORT]. This is referred to a reason; see Section 2.4 of [QUIC-TRANSPORT]. This is referred to
as a "stream error." An HTTP/3 implementation can decide to close a as a "stream error". An HTTP/3 implementation can decide to close a
QUIC stream and communicate the type of error. Wire encodings of QUIC stream and communicate the type of error. Wire encodings of
error codes are defined in Section 8.1. Stream errors are distinct error codes are defined in Section 8.1. Stream errors are distinct
from HTTP status codes which indicate error conditions. Stream from HTTP status codes that indicate error conditions. Stream errors
errors indicate that the sender did not transfer or consume the full indicate that the sender did not transfer or consume the full request
request or response, while HTTP status codes indicate the result of a or response, while HTTP status codes indicate the result of a request
request that was successfully received. that was successfully received.
If an entire connection needs to be terminated, QUIC similarly If an entire connection needs to be terminated, QUIC similarly
provides mechanisms to communicate a reason; see Section 5.3 of provides mechanisms to communicate a reason; see Section 5.3 of
[QUIC-TRANSPORT]. This is referred to as a "connection error." [QUIC-TRANSPORT]. This is referred to as a "connection error".
Similar to stream errors, an HTTP/3 implementation can terminate a Similar to stream errors, an HTTP/3 implementation can terminate a
QUIC connection and communicate the reason using an error code from QUIC connection and communicate the reason using an error code from
Section 8.1. Section 8.1.
Although the reasons for closing streams and connections are called Although the reasons for closing streams and connections are called
"errors," these actions do not necessarily indicate a problem with "errors", these actions do not necessarily indicate a problem with
the connection or either implementation. For example, a stream can the connection or either implementation. For example, a stream can
be reset if the requested resource is no longer needed. be reset if the requested resource is no longer needed.
An endpoint MAY choose to treat a stream error as a connection error An endpoint MAY choose to treat a stream error as a connection error
under certain circumstances, closing the entire connection in under certain circumstances, closing the entire connection in
response to a condition on a single stream. Implementations need to response to a condition on a single stream. Implementations need to
consider the impact on outstanding requests before making this consider the impact on outstanding requests before making this
choice. choice.
Because new error codes can be defined without negotiation (see Because new error codes can be defined without negotiation (see
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of an unknown error code MUST be treated as equivalent to of an unknown error code MUST be treated as equivalent to
H3_NO_ERROR. However, closing a stream can have other effects H3_NO_ERROR. However, closing a stream can have other effects
regardless of the error code; for example, see Section 4.1. regardless of the error code; for example, see Section 4.1.
8.1. HTTP/3 Error Codes 8.1. HTTP/3 Error Codes
The following error codes are defined for use when abruptly The following error codes are defined for use when abruptly
terminating streams, aborting reading of streams, or immediately terminating streams, aborting reading of streams, or immediately
closing HTTP/3 connections. closing HTTP/3 connections.
H3_NO_ERROR (0x100): No error. This is used when the connection or H3_NO_ERROR (0x0100): No error. This is used when the connection or
stream needs to be closed, but there is no error to signal. stream needs to be closed, but there is no error to signal.
H3_GENERAL_PROTOCOL_ERROR (0x101): Peer violated protocol H3_GENERAL_PROTOCOL_ERROR (0x0101): Peer violated protocol
requirements in a way that does not match a more specific error requirements in a way that does not 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.
H3_INTERNAL_ERROR (0x102): An internal error has occurred in the H3_INTERNAL_ERROR (0x0102): An internal error has occurred in the
HTTP stack. HTTP stack.
H3_STREAM_CREATION_ERROR (0x103): The endpoint detected that its H3_STREAM_CREATION_ERROR (0x0103): The endpoint detected that its
peer created a stream that it will not accept. peer created a stream that it will not accept.
H3_CLOSED_CRITICAL_STREAM (0x104): A stream required by the HTTP/3 H3_CLOSED_CRITICAL_STREAM (0x0104): A stream required by the HTTP/3
connection was closed or reset. connection was closed or reset.
H3_FRAME_UNEXPECTED (0x105): A frame was received that was not H3_FRAME_UNEXPECTED (0x0105): A frame was received that was not
permitted in the current state or on the current stream. permitted in the current state or on the current stream.
H3_FRAME_ERROR (0x106): A frame that fails to satisfy layout H3_FRAME_ERROR (0x0106): A frame that fails to satisfy layout
requirements or with an invalid size was received. requirements or with an invalid size was received.
H3_EXCESSIVE_LOAD (0x107): The endpoint detected that its peer is H3_EXCESSIVE_LOAD (0x0107): 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.
H3_ID_ERROR (0x108): A Stream ID or Push ID was used incorrectly, H3_ID_ERROR (0x0108): A stream ID or push ID was used incorrectly,
such as exceeding a limit, reducing a limit, or being reused. such as exceeding a limit, reducing a limit, or being reused.
H3_SETTINGS_ERROR (0x109): An endpoint detected an error in the H3_SETTINGS_ERROR (0x0109): An endpoint detected an error in the
payload of a SETTINGS frame. payload of a SETTINGS frame.
H3_MISSING_SETTINGS (0x10a): No SETTINGS frame was received at the H3_MISSING_SETTINGS (0x010a): No SETTINGS frame was received at the
beginning of the control stream. beginning of the control stream.
H3_REQUEST_REJECTED (0x10b): A server rejected a request without H3_REQUEST_REJECTED (0x010b): A server rejected a request without
performing any application processing. performing any application processing.
H3_REQUEST_CANCELLED (0x10c): The request or its response (including H3_REQUEST_CANCELLED (0x010c): The request or its response
pushed response) is cancelled. (including pushed response) is cancelled.
H3_REQUEST_INCOMPLETE (0x10d): The client's stream terminated H3_REQUEST_INCOMPLETE (0x010d): The client's stream terminated
without containing a fully-formed request. without containing a fully formed request.
H3_MESSAGE_ERROR (0x10e): An HTTP message was malformed and cannot H3_MESSAGE_ERROR (0x010e): An HTTP message was malformed and cannot
be processed. be processed.
H3_CONNECT_ERROR (0x10f): The TCP connection established in response H3_CONNECT_ERROR (0x010f): The TCP connection established in
to a CONNECT request was reset or abnormally closed. response to a CONNECT request was reset or abnormally closed.
H3_VERSION_FALLBACK (0x110): The requested operation cannot be H3_VERSION_FALLBACK (0x0110): The requested operation cannot be
served over HTTP/3. The peer should retry over HTTP/1.1. served over HTTP/3. The peer should retry over HTTP/1.1.
Error codes of the format "0x1f * N + 0x21" for non-negative integer Error codes of the format 0x1f * N + 0x21 for non-negative integer
values of N are reserved to exercise the requirement that unknown values of N are reserved to exercise the requirement that unknown
error codes be treated as equivalent to H3_NO_ERROR (Section 9). error codes be treated as equivalent to H3_NO_ERROR (Section 9).
Implementations SHOULD select an error code from this space with some Implementations SHOULD select an error code from this space with some
probability when they would have sent H3_NO_ERROR. probability when they would have sent H3_NO_ERROR.
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
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defining new methods, status codes, or fields. defining new methods, status codes, or fields.
Extensions are permitted to use new frame types (Section 7.2), new Extensions are permitted to use new frame types (Section 7.2), new
settings (Section 7.2.4.1), new error codes (Section 8), or new settings (Section 7.2.4.1), new error codes (Section 8), or new
unidirectional stream types (Section 6.2). Registries are unidirectional stream types (Section 6.2). Registries are
established for managing these extension points: frame types established for managing these extension points: frame types
(Section 11.2.1), settings (Section 11.2.2), error codes (Section 11.2.1), settings (Section 11.2.2), error codes
(Section 11.2.3), and stream types (Section 11.2.4). (Section 11.2.3), and stream types (Section 11.2.4).
Implementations MUST ignore unknown or unsupported values in all Implementations MUST ignore unknown or unsupported values in all
extensible protocol elements. Implementations MUST discard frames extensible protocol elements. Implementations MUST discard data or
and abort reading on unidirectional streams that have unknown or abort reading on unidirectional streams that have unknown or
unsupported types. This means that any of these extension points can unsupported types. This means that any of these extension points can
be safely used by extensions without prior arrangement or be safely used by extensions without prior arrangement or
negotiation. However, where a known frame type is required to be in 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 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 the control stream (see Section 6.2.1), an unknown frame type does
not satisfy that requirement and SHOULD be treated as an error. not satisfy that requirement and SHOULD be treated as an error.
Extensions that could change the semantics of existing protocol Extensions that could change the semantics of existing protocol
components MUST be negotiated before being used. For example, an components MUST be negotiated before being used. For example, an
extension that changes the layout of the HEADERS frame cannot be used extension that changes the layout of the HEADERS frame cannot be used
until the peer has given a positive signal that this is acceptable. until the peer has given a positive signal that this is acceptable.
Coordinating when such a revised layout comes into effect could prove Coordinating when such a revised layout comes into effect could prove
complex. As such, allocating new identifiers for new definitions of complex. As such, allocating new identifiers for new definitions of
existing protocol elements is likely to be more effective. existing protocol elements is likely to be more effective.
This document does not mandate a specific method for negotiating the This document does not mandate a specific method for negotiating the
use of an extension but notes that a setting (Section 7.2.4.1) could use of an extension, but it notes that a setting (Section 7.2.4.1)
be used for that purpose. If both peers set a value that indicates could be used for that purpose. If both peers set a value that
willingness to use the extension, then the extension can be used. If indicates willingness to use the extension, then the extension can be
a setting is used for extension negotiation, the default value MUST used. If a setting is used for extension negotiation, the default
be defined in such a fashion that the extension is disabled if the value MUST be defined in such a fashion that the extension is
setting is omitted. disabled if the 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. However, many of the considerations from of HTTP/2 with TLS. However, many of the considerations from
Section 10 of [HTTP2] apply to [QUIC-TRANSPORT] and are discussed in Section 10 of [HTTP/2] apply to [QUIC-TRANSPORT] and are discussed in
that document. that document.
10.1. Server Authority 10.1. Server Authority
HTTP/3 relies on the HTTP definition of authority. The security HTTP/3 relies on the HTTP definition of authority. The security
considerations of establishing authority are discussed in considerations of establishing authority are discussed in
Section 17.1 of [SEMANTICS]. Section 17.1 of [HTTP].
10.2. Cross-Protocol Attacks 10.2. Cross-Protocol Attacks
The use of ALPN in the TLS and QUIC handshakes establishes the target The use of ALPN in the TLS and QUIC handshakes establishes the target
application protocol before application-layer bytes are processed. application protocol before application-layer bytes are processed.
This ensures that endpoints have strong assurances that peers are This ensures that endpoints have strong assurances that peers are
using the same protocol. using the same protocol.
This does not guarantee protection from all cross-protocol attacks. This does not guarantee protection from all cross-protocol attacks.
Section 21.5 of [QUIC-TRANSPORT] describes some ways in which the Section 21.5 of [QUIC-TRANSPORT] describes some ways in which the
plaintext of QUIC packets can be used to perform request forgery plaintext of QUIC packets can be used to perform request forgery
against endpoints that don't use authenticated transports. against endpoints that don't use authenticated transports.
10.3. Intermediary Encapsulation Attacks 10.3. Intermediary-Encapsulation Attacks
The HTTP/3 field encoding allows the expression of names that are not The HTTP/3 field encoding allows the expression of names that are not
valid field names in the syntax used by HTTP (Section 5.1 of valid field names in the syntax used by HTTP (Section 5.1 of [HTTP]).
[SEMANTICS]). Requests or responses containing invalid field names Requests or responses containing invalid field names MUST be treated
MUST be treated as malformed (Section 4.1.3). An intermediary as malformed. Therefore, an intermediary cannot translate an HTTP/3
therefore cannot translate an HTTP/3 request or response containing request or response containing an invalid field name into an HTTP/1.1
an invalid field name into an HTTP/1.1 message. message.
Similarly, HTTP/3 can transport field values that are not valid. Similarly, HTTP/3 can transport field values that are not valid.
While most values that can be encoded will not alter field parsing, While most values that can be encoded will not alter field parsing,
carriage return (CR, ASCII 0xd), line feed (LF, ASCII 0xa), and the carriage return (ASCII 0x0d), line feed (ASCII 0x0a), and the null
zero character (NUL, ASCII 0x0) might be exploited by an attacker if character (ASCII 0x00) might be exploited by an attacker if they are
they are translated verbatim. Any request or response that contains translated verbatim. Any request or response that contains a
a character not permitted in a field value MUST be treated as character not permitted in a field value MUST be treated as
malformed (Section 4.1.3). Valid characters are defined by the malformed. Valid characters are defined by the "field-content" ABNF
"field-content" ABNF rule in Section 5.5 of [SEMANTICS]. rule in Section 5.5 of [HTTP].
10.4. Cacheability of Pushed Responses 10.4. Cacheability of Pushed Responses
Pushed responses do not have an explicit request from the client; the Pushed responses do not have an explicit request from the client; the
request is provided by the server in the PUSH_PROMISE frame. request is provided by the server in the PUSH_PROMISE frame.
Caching responses that are pushed is possible based on the guidance Caching responses that are pushed is possible based on the guidance
provided by the origin server in the Cache-Control header field. provided by the origin server in the Cache-Control header field.
However, this can cause issues if a single server hosts more than one However, this can cause issues if a single server hosts more than one
tenant. For example, a server might offer multiple users each a tenant. For example, a server might offer multiple users each a
small portion of its URI space. small portion of its URI space.
Where multiple tenants share space on the same server, that server Where multiple tenants share space on the same server, that server
MUST ensure that tenants are not able to push representations of MUST ensure that tenants are not able to push representations of
resources that they do not have authority over. Failure to enforce resources that they do not have authority over. Failure to enforce
this would allow a tenant to provide a representation that would be this would allow a tenant to provide a representation that would be
served out of cache, overriding the actual representation that the served out of cache, overriding the actual representation that the
authoritative tenant provides. authoritative tenant provides.
Clients are required to reject pushed responses for which an origin Clients are required to reject pushed responses for which an origin
server is not authoritative; see Section 4.4. server is not authoritative; see Section 4.6.
10.5. Denial-of-Service Considerations 10.5. Denial-of-Service Considerations
An HTTP/3 connection can demand a greater commitment of resources to An HTTP/3 connection can demand a greater commitment of resources to
operate than an HTTP/1.1 or HTTP/2 connection. The use of field operate than an HTTP/1.1 or HTTP/2 connection. The use of field
compression and flow control depend on a commitment of resources for compression and flow control depend on a commitment of resources for
storing a greater amount of state. Settings for these features storing a greater amount of state. Settings for these features
ensure that memory commitments for these features are strictly ensure that memory commitments for these features are strictly
bounded. bounded.
The number of PUSH_PROMISE frames is constrained in a similar The number of PUSH_PROMISE frames is constrained in a similar
fashion. A client that accepts server push SHOULD limit the number fashion. A client that accepts server push SHOULD limit the number
of Push IDs it issues at a time. of push IDs it issues at a time.
Processing capacity cannot be guarded as effectively as state Processing capacity cannot be guarded as effectively as state
capacity. capacity.
The ability to send undefined protocol elements that the peer is The ability to send undefined protocol elements that the peer is
required to ignore can be abused to cause a peer to expend additional required to ignore can be abused to cause a peer to expend additional
processing time. This might be done by setting multiple undefined processing time. This might be done by setting multiple undefined
SETTINGS parameters, unknown frame types, or unknown stream types. SETTINGS parameters, unknown frame types, or unknown stream types.
Note, however, that some uses are entirely legitimate, such as Note, however, that some uses are entirely legitimate, such as
optional-to-understand extensions and padding to increase resistance optional-to-understand extensions and padding to increase resistance
skipping to change at page 46, line 32 skipping to change at line 2074
potential abuses. potential abuses.
All these features -- i.e., server push, unknown protocol elements, All these features -- i.e., server push, unknown protocol elements,
field compression -- have legitimate uses. These features become a field compression -- have legitimate uses. These features become a
burden only when they are used unnecessarily or to excess. burden only when they are used unnecessarily or to excess.
An endpoint that does not monitor such behavior exposes itself to a An endpoint that does not monitor such behavior exposes itself to a
risk of denial-of-service attack. Implementations SHOULD track the risk of denial-of-service attack. Implementations SHOULD track the
use of these features and set limits on their use. An endpoint MAY use of these features and set limits on their use. An endpoint MAY
treat activity that is suspicious as a connection error of type treat activity that is suspicious as a connection error of type
H3_EXCESSIVE_LOAD (Section 8), but false positives will result in H3_EXCESSIVE_LOAD, but false positives will result in disrupting
disrupting valid connections and requests. valid connections and requests.
10.5.1. Limits on Field Section Size 10.5.1. Limits on Field Section Size
A large field section (Section 4.1) can cause an implementation to A large field section (Section 4.1) can cause an implementation to
commit a large amount of state. Header fields that are critical for commit a large amount of state. Header fields that are critical for
routing can appear toward the end of a header section, which prevents routing can appear toward the end of a header section, which prevents
streaming of the header section to its ultimate destination. This streaming of the header section to its ultimate destination. This
ordering and other reasons, such as ensuring cache correctness, mean ordering and other reasons, such as ensuring cache correctness, mean
that an endpoint likely needs to buffer the entire header section. that an endpoint likely needs to buffer the entire header section.
Since there is no hard limit to the size of a field section, some Since there is no hard limit to the size of a field section, some
endpoints could be forced to commit a large amount of available endpoints could be forced to commit a large amount of available
memory for header fields. memory for header fields.
An endpoint can use the SETTINGS_MAX_FIELD_SECTION_SIZE An endpoint can use the SETTINGS_MAX_FIELD_SECTION_SIZE
(Section 4.1.1.3) setting to advise peers of limits that might apply (Section 4.2.2) setting to advise peers of limits that might apply on
on the size of field sections. This setting is only advisory, so the size of field sections. This setting is only advisory, so
endpoints MAY choose to send field sections that exceed this limit endpoints MAY choose to send field sections that exceed this limit
and risk having the request or response being treated as malformed. and risk having the request or response being treated as malformed.
This setting is specific to an HTTP/3 connection, so any request or This setting is specific to an HTTP/3 connection, so any request or
response could encounter a hop with a lower, unknown limit. An response could encounter a hop with a lower, unknown limit. An
intermediary can attempt to avoid this problem by passing on values intermediary can attempt to avoid this problem by passing on values
presented by different peers, but they are not obligated to do so. presented by different peers, but they are not obligated to do so.
A server that receives a larger field section than it is willing to A server that receives a larger field section than it is willing to
handle can send an HTTP 431 (Request Header Fields Too Large) status handle can send an HTTP 431 (Request Header Fields Too Large) status
code ([RFC6585]). A client can discard responses that it cannot code ([RFC6585]). A client can discard responses that it cannot
skipping to change at page 47, line 31 skipping to change at line 2122
A proxy might also maintain some resources for a TCP connection A proxy might also maintain some resources for a TCP connection
beyond the closing of the stream that carries the CONNECT request, beyond the closing of the stream that carries the CONNECT request,
since the outgoing TCP connection remains in the TIME_WAIT state. To since the outgoing TCP connection remains in the TIME_WAIT state. To
account for this, a proxy might delay increasing the QUIC stream account for this, a proxy might delay increasing the QUIC stream
limits for some time after a TCP connection terminates. limits for some time after a TCP connection terminates.
10.6. Use of Compression 10.6. Use of Compression
Compression can allow an attacker to recover secret data when it is Compression can allow an attacker to recover secret data when it is
compressed in the same context as data under attacker control. compressed in the same context as data under attacker control.
HTTP/3 enables compression of fields (Section 4.1.1); the following HTTP/3 enables compression of fields (Section 4.2); the following
concerns also apply to the use of HTTP compressed content-codings; concerns also apply to the use of HTTP compressed content-codings;
see Section 8.4.1 of [SEMANTICS]. see Section 8.4.1 of [HTTP].
There are demonstrable attacks on compression that exploit the There are demonstrable attacks on compression that exploit the
characteristics of the web (e.g., [BREACH]). The attacker induces characteristics of the web (e.g., [BREACH]). The attacker induces
multiple requests containing varying plaintext, observing the length multiple requests containing varying plaintext, observing the length
of the resulting ciphertext in each, which reveals a shorter length of the resulting ciphertext in each, which reveals a shorter length
when a guess about the secret is correct. when a guess about the secret is correct.
Implementations communicating on a secure channel MUST NOT compress Implementations communicating on a secure channel MUST NOT compress
content that includes both confidential and attacker-controlled data content that includes both confidential and attacker-controlled data
unless separate compression contexts are used for each source of unless separate compression contexts are used for each source of
skipping to change at page 48, line 15 skipping to change at line 2151
10.7. Padding and Traffic Analysis 10.7. Padding and Traffic Analysis
Padding can be used to obscure the exact size of frame content and is Padding can be used to obscure the exact size of frame content and is
provided to mitigate specific attacks within HTTP, for example, provided to mitigate specific attacks within HTTP, for example,
attacks where compressed content includes both attacker-controlled attacks where compressed content includes both attacker-controlled
plaintext and secret data (e.g., [BREACH]). plaintext and secret data (e.g., [BREACH]).
Where HTTP/2 employs PADDING frames and Padding fields in other Where HTTP/2 employs PADDING frames and Padding fields in other
frames to make a connection more resistant to traffic analysis, frames to make a connection more resistant to traffic analysis,
HTTP/3 can either rely on transport-layer padding or employ the HTTP/3 can either rely on transport-layer padding or employ the
reserved frame and stream types discussed in Section 7.2.8 and reserved frame and stream types discussed in Sections 7.2.8 and
Section 6.2.3. These methods of padding produce different results in 6.2.3. These methods of padding produce different results in terms
terms of the granularity of padding, how padding is arranged in of the granularity of padding, how padding is arranged in relation to
relation to the information that is being protected, whether padding the information that is being protected, whether padding is applied
is applied in the case of packet loss, and how an implementation in the case of packet loss, and how an implementation might control
might control padding. padding.
Reserved stream types can be used to give the appearance of sending Reserved stream types can be used to give the appearance of sending
traffic even when the connection is idle. Because HTTP traffic often traffic even when the connection is idle. Because HTTP traffic often
occurs in bursts, apparent traffic can be used to obscure the timing occurs in bursts, apparent traffic can be used to obscure the timing
or duration of such bursts, even to the point of appearing to send a or duration of such bursts, even to the point of appearing to send a
constant stream of data. However, as such traffic is still flow constant stream of data. However, as such traffic is still flow
controlled by the receiver, a failure to promptly drain such streams controlled by the receiver, a failure to promptly drain such streams
and provide additional flow control credit can limit the sender's and provide additional flow-control credit can limit the sender's
ability to send real traffic. ability to send real traffic.
To mitigate attacks that rely on compression, disabling or limiting To mitigate attacks that rely on compression, disabling or limiting
compression might be preferable to padding as a countermeasure. compression might be preferable to padding as a countermeasure.
Use of padding can result in less protection than might seem Use of padding can result in less protection than might seem
immediately obvious. Redundant padding could even be immediately obvious. Redundant padding could even be
counterproductive. At best, padding only makes it more difficult for counterproductive. At best, padding only makes it more difficult for
an attacker to infer length information by increasing the number of an attacker to infer length information by increasing the number of
frames an attacker has to observe. Incorrectly implemented padding frames an attacker has to observe. Incorrectly implemented padding
skipping to change at page 49, line 46 skipping to change at line 2230
different origins allows for correlation of activity across those different origins allows for correlation of activity across those
origins. origins.
Several features of QUIC solicit immediate responses and can be used Several features of QUIC solicit immediate responses and can be used
by an endpoint to measure latency to their peer; this might have by an endpoint to measure latency to their peer; this might have
privacy implications in certain scenarios. privacy implications in certain scenarios.
11. IANA Considerations 11. IANA Considerations
This document registers a new ALPN protocol ID (Section 11.1) and This document registers a new ALPN protocol ID (Section 11.1) and
creates new registries that manage the assignment of codepoints in creates new registries that manage the assignment of code points in
HTTP/3. HTTP/3.
11.1. Registration of HTTP/3 Identification String 11.1. Registration of HTTP/3 Identification String
This document creates a new registration for the identification of This document creates a new registration for the identification of
HTTP/3 in the "Application Layer Protocol Negotiation (ALPN) Protocol HTTP/3 in the "TLS Application-Layer Protocol Negotiation (ALPN)
IDs" registry established in [RFC7301]. Protocol IDs" registry established in [RFC7301].
The "h3" string identifies HTTP/3: The "h3" string identifies HTTP/3:
Protocol: HTTP/3 Protocol: HTTP/3
Identification Sequence: 0x68 0x33 ("h3") Identification Sequence: 0x68 0x33 ("h3")
Specification: This document Specification: This document
11.2. New Registries 11.2. New Registries
New registries created in this document operate under the QUIC New registries created in this document operate under the QUIC
registration policy documented in Section 22.1 of [QUIC-TRANSPORT]. registration policy documented in Section 22.1 of [QUIC-TRANSPORT].
These registries all include the common set of fields listed in These registries all include the common set of fields listed in
Section 22.1.1 of [QUIC-TRANSPORT]. These registries [SHALL be/are] Section 22.1.1 of [QUIC-TRANSPORT]. These registries are collected
collected under a "Hypertext Transfer Protocol version 3 (HTTP/3) under the "Hypertext Transfer Protocol version 3 (HTTP/3)" heading.
Parameters" heading.
The initial allocations in these registries created in this document The initial allocations in these registries are all assigned
are all assigned permanent status and list a change controller of the permanent status and list a change controller of the IETF and a
IETF and a contact of the HTTP working group (ietf-http-wg@w3.org). contact of the HTTP working group (ietf-http-wg@w3.org).
11.2.1. Frame Types 11.2.1. Frame Types
This document establishes a registry for HTTP/3 frame type codes. This document establishes a registry for HTTP/3 frame type codes.
The "HTTP/3 Frame Type" registry governs a 62-bit space. This The "HTTP/3 Frame Types" registry governs a 62-bit space. This
registry follows the QUIC registry policy; see Section 11.2. registry follows the QUIC registry policy; see Section 11.2.
Permanent registrations in this registry are assigned using the Permanent registrations in this registry are assigned using the
Specification Required policy ([RFC8126]), except for values between Specification Required policy ([RFC8126]), except for values between
0x00 and 0x3f (in hexadecimal; inclusive), which are assigned using 0x00 and 0x3f (in hexadecimal; inclusive), which are assigned using
Standards Action or IESG Approval as defined in Sections 4.9 and 4.10 Standards Action or IESG Approval as defined in Sections 4.9 and 4.10
of [RFC8126]. of [RFC8126].
While this registry is separate from the "HTTP/2 Frame Type" registry While this registry is separate from the "HTTP/2 Frame Type" registry
defined in [HTTP2], it is preferable that the assignments parallel defined in [HTTP/2], it is preferable that the assignments parallel
each other where the code spaces overlap. If an entry is present in each other where the code spaces overlap. If an entry is present in
only one registry, every effort SHOULD be made to avoid assigning the only one registry, every effort SHOULD be made to avoid assigning the
corresponding value to an unrelated operation. Expert reviewers MAY corresponding value to an unrelated operation. Expert reviewers MAY
reject unrelated registrations which would conflict with the same reject unrelated registrations that would conflict with the same
value in the corresponding registry. value in the corresponding registry.
In addition to common fields as described in Section 11.2, permanent In addition to common fields as described in Section 11.2, permanent
registrations in this registry MUST include the following field: registrations in this registry MUST include the following field:
Frame Type: A name or label for the frame type. Frame Type: A name or label for the frame type.
Specifications of frame types MUST include a description of the frame Specifications of frame types MUST include a description of the frame
layout and its semantics, including any parts of the frame that are layout and its semantics, including any parts of the frame that are
conditionally present. conditionally present.
The entries in Table 2 are registered by this document. The entries in Table 2 are registered by this document.
+==============+=======+===============+ +==============+=======+===============+
| Frame Type | Value | Specification | | Frame Type | Value | Specification |
+==============+=======+===============+ +==============+=======+===============+
| DATA | 0x0 | Section 7.2.1 | | DATA | 0x00 | Section 7.2.1 |
+--------------+-------+---------------+ +--------------+-------+---------------+
| HEADERS | 0x1 | Section 7.2.2 | | HEADERS | 0x01 | Section 7.2.2 |
+--------------+-------+---------------+ +--------------+-------+---------------+
| Reserved | 0x2 | N/A | | Reserved | 0x02 | This document |
+--------------+-------+---------------+ +--------------+-------+---------------+
| CANCEL_PUSH | 0x3 | Section 7.2.3 | | CANCEL_PUSH | 0x03 | Section 7.2.3 |
+--------------+-------+---------------+ +--------------+-------+---------------+
| SETTINGS | 0x4 | Section 7.2.4 | | SETTINGS | 0x04 | Section 7.2.4 |
+--------------+-------+---------------+ +--------------+-------+---------------+
| PUSH_PROMISE | 0x5 | Section 7.2.5 | | PUSH_PROMISE | 0x05 | Section 7.2.5 |
+--------------+-------+---------------+ +--------------+-------+---------------+
| Reserved | 0x6 | N/A | | Reserved | 0x06 | This document |
+--------------+-------+---------------+ +--------------+-------+---------------+
| GOAWAY | 0x7 | Section 7.2.6 | | GOAWAY | 0x07 | Section 7.2.6 |
+--------------+-------+---------------+ +--------------+-------+---------------+
| Reserved | 0x8 | N/A | | Reserved | 0x08 | This document |
+--------------+-------+---------------+ +--------------+-------+---------------+
| Reserved | 0x9 | N/A | | Reserved | 0x09 | This document |
+--------------+-------+---------------+ +--------------+-------+---------------+
| MAX_PUSH_ID | 0xd | Section 7.2.7 | | MAX_PUSH_ID | 0x0d | Section 7.2.7 |
+--------------+-------+---------------+ +--------------+-------+---------------+
Table 2: Initial HTTP/3 Frame Types Table 2: Initial HTTP/3 Frame Types
Each code of the format "0x1f * N + 0x21" for non-negative integer Each code of the format 0x1f * N + 0x21 for non-negative integer
values of N (that is, 0x21, 0x40, ..., through 0x3ffffffffffffffe) values of N (that is, 0x21, 0x40, ..., through 0x3ffffffffffffffe)
MUST NOT be assigned by IANA and MUST NOT appear in the listing of MUST NOT be assigned by IANA and MUST NOT appear in the listing of
assigned values. assigned values.
11.2.2. Settings Parameters 11.2.2. 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 registry "HTTP/3 Settings" registry governs a 62-bit space. This registry
follows the QUIC registry policy; see Section 11.2. Permanent follows the QUIC registry policy; see Section 11.2. Permanent
registrations in this registry are assigned using the Specification registrations in this registry are assigned using the Specification
Required policy ([RFC8126]), except for values between 0x00 and 0x3f Required policy ([RFC8126]), except for values between 0x00 and 0x3f
(in hexadecimal; inclusive), which are assigned using Standards (in hexadecimal; inclusive), which are assigned using Standards
Action or IESG Approval as defined in Sections 4.9 and 4.10 of Action or IESG Approval as defined in Sections 4.9 and 4.10 of
[RFC8126]. [RFC8126].
While this registry is separate from the "HTTP/2 Settings" registry While this registry is separate from the "HTTP/2 Settings" registry
defined in [HTTP2], it is preferable that the assignments parallel defined in [HTTP/2], 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. Expert reviewers MAY reject unrelated an unrelated operation. Expert reviewers MAY reject unrelated
registrations which would conflict with the same value in the registrations that would conflict with the same value in the
corresponding registry. corresponding registry.
In addition to common fields as described in Section 11.2, permanent In addition to common fields as described in Section 11.2, permanent
registrations in this registry MUST include the following fields: registrations in this registry MUST include the following fields:
Setting Name: A symbolic name for the setting. Specifying a setting Setting Name: A symbolic name for the setting. Specifying a setting
name is optional. name is optional.
Default: The value of the setting unless otherwise indicated. A Default: The value of the setting unless otherwise indicated. A
default SHOULD be the most restrictive possible value. default SHOULD be the most restrictive possible value.
The entries in Table 3 are registered by this document. The entries in Table 3 are registered by this document.
+========================+=======+=================+===========+ +========================+=======+=================+===========+
| Setting Name | Value | Specification | Default | | Setting Name | Value | Specification | Default |
+========================+=======+=================+===========+ +========================+=======+=================+===========+
| Reserved | 0x0 | N/A | N/A | | Reserved | 0x00 | This document | N/A |
+------------------------+-------+-----------------+-----------+ +------------------------+-------+-----------------+-----------+
| Reserved | 0x2 | N/A | N/A | | Reserved | 0x02 | This document | N/A |
+------------------------+-------+-----------------+-----------+ +------------------------+-------+-----------------+-----------+
| Reserved | 0x3 | N/A | N/A | | Reserved | 0x03 | This document | N/A |
+------------------------+-------+-----------------+-----------+ +------------------------+-------+-----------------+-----------+
| Reserved | 0x4 | N/A | N/A | | Reserved | 0x04 | This document | N/A |
+------------------------+-------+-----------------+-----------+ +------------------------+-------+-----------------+-----------+
| Reserved | 0x5 | N/A | N/A | | Reserved | 0x05 | This document | N/A |
+------------------------+-------+-----------------+-----------+ +------------------------+-------+-----------------+-----------+
| MAX_FIELD_SECTION_SIZE | 0x6 | Section 7.2.4.1 | Unlimited | | MAX_FIELD_SECTION_SIZE | 0x06 | Section 7.2.4.1 | Unlimited |
+------------------------+-------+-----------------+-----------+ +------------------------+-------+-----------------+-----------+
Table 3: Initial HTTP/3 Settings Table 3: Initial HTTP/3 Settings
Each code of the format "0x1f * N + 0x21" for non-negative integer For formatting reasons, setting names can be abbreviated by removing
the 'SETTINGS_' prefix.
Each code of the format 0x1f * N + 0x21 for non-negative integer
values of N (that is, 0x21, 0x40, ..., through 0x3ffffffffffffffe) values of N (that is, 0x21, 0x40, ..., through 0x3ffffffffffffffe)
MUST NOT be assigned by IANA and MUST NOT appear in the listing of MUST NOT be assigned by IANA and MUST NOT appear in the listing of
assigned values. assigned values.
11.2.3. Error Codes 11.2.3. Error Codes
This document establishes a registry for HTTP/3 error codes. The This document establishes a registry for HTTP/3 error codes. The
"HTTP/3 Error Code" registry manages a 62-bit space. This registry "HTTP/3 Error Codes" registry manages a 62-bit space. This registry
follows the QUIC registry policy; see Section 11.2. Permanent follows the QUIC registry policy; see Section 11.2. Permanent
registrations in this registry are assigned using the Specification registrations in this registry are assigned using the Specification
Required policy ([RFC8126]), except for values between 0x00 and 0x3f Required policy ([RFC8126]), except for values between 0x00 and 0x3f
(in hexadecimal; inclusive), which are assigned using Standards (in hexadecimal; inclusive), which are assigned using Standards
Action or IESG Approval as defined in Sections 4.9 and 4.10 of Action or IESG Approval as defined in Sections 4.9 and 4.10 of
[RFC8126]. [RFC8126].
Registrations for error codes are required to include a description Registrations for error codes are required to include a description
of the error code. An expert reviewer is advised to examine new of the error code. An expert reviewer is advised to examine new
registrations for possible duplication with existing error codes. registrations for possible duplication with existing error codes.
skipping to change at page 53, line 40 skipping to change at line 2408
this registry MUST include the following field: this registry MUST include the following field:
Name: A name for the error code. Name: A name for the error code.
Description: A brief description of the error code semantics. Description: A brief description of the error code semantics.
The entries in Table 4 are registered by this document. These error The entries in Table 4 are registered by this document. These error
codes were selected from the range that operates on a Specification codes were selected from the range that operates on a Specification
Required policy to avoid collisions with HTTP/2 error codes. Required policy to avoid collisions with HTTP/2 error codes.
+===========================+=======+==============+===============+ +===========================+========+==============+===============+
| Name | Value | Description | Specification | | Name | Value | Description | Specification |
+===========================+=======+==============+===============+ +===========================+========+==============+===============+
| H3_NO_ERROR | 0x100 | No error | Section 8.1 | | H3_NO_ERROR | 0x0100 | No error | Section 8.1 |
+---------------------------+-------+--------------+---------------+ +---------------------------+--------+--------------+---------------+
| H3_GENERAL_PROTOCOL_ERROR | 0x101 | General | Section 8.1 | | H3_GENERAL_PROTOCOL_ERROR | 0x0101 | General | Section 8.1 |
| | | protocol | | | | | protocol | |
| | | error | | | | | error | |
+---------------------------+-------+--------------+---------------+ +---------------------------+--------+--------------+---------------+
| H3_INTERNAL_ERROR | 0x102 | Internal | Section 8.1 | | H3_INTERNAL_ERROR | 0x0102 | Internal | Section 8.1 |
| | | error | | | | | error | |
+---------------------------+-------+--------------+---------------+ +---------------------------+--------+--------------+---------------+
| H3_STREAM_CREATION_ERROR | 0x103 | Stream | Section 8.1 | | H3_STREAM_CREATION_ERROR | 0x0103 | Stream | Section 8.1 |
| | | creation | | | | | creation | |
| | | error | | | | | error | |
+---------------------------+-------+--------------+---------------+ +---------------------------+--------+--------------+---------------+
| H3_CLOSED_CRITICAL_STREAM | 0x104 | Critical | Section 8.1 | | H3_CLOSED_CRITICAL_STREAM | 0x0104 | Critical | Section 8.1 |
| | | stream was | | | | | stream was | |
| | | closed | | | | | closed | |
+---------------------------+-------+--------------+---------------+ +---------------------------+--------+--------------+---------------+
| H3_FRAME_UNEXPECTED | 0x105 | Frame not | Section 8.1 | | H3_FRAME_UNEXPECTED | 0x0105 | Frame not | Section 8.1 |
| | | permitted in | | | | | permitted | |
| | | the current | | | | | in the | |
| | | state | | | | | current | |
+---------------------------+-------+--------------+---------------+ | | | state | |
| H3_FRAME_ERROR | 0x106 | Frame | Section 8.1 | +---------------------------+--------+--------------+---------------+
| | | violated | | | H3_FRAME_ERROR | 0x0106 | Frame | Section 8.1 |
| | | layout or | | | | | violated | |
| | | size rules | | | | | layout or | |
+---------------------------+-------+--------------+---------------+ | | | size rules | |
| H3_EXCESSIVE_LOAD | 0x107 | Peer | Section 8.1 | +---------------------------+--------+--------------+---------------+
| | | generating | | | H3_EXCESSIVE_LOAD | 0x0107 | Peer | Section 8.1 |
| | | excessive | | | | | generating | |
| | | load | | | | | excessive | |
+---------------------------+-------+--------------+---------------+ | | | load | |
| H3_ID_ERROR | 0x108 | An | Section 8.1 | +---------------------------+--------+--------------+---------------+
| | | identifier | | | H3_ID_ERROR | 0x0108 | An | Section 8.1 |
| | | was used | | | | | identifier | |
| | | incorrectly | | | | | was used | |
+---------------------------+-------+--------------+---------------+ | | | incorrectly | |
| H3_SETTINGS_ERROR | 0x109 | SETTINGS | Section 8.1 | +---------------------------+--------+--------------+---------------+
| | | frame | | | H3_SETTINGS_ERROR | 0x0109 | SETTINGS | Section 8.1 |
| | | contained | | | | | frame | |
| | | invalid | | | | | contained | |
| | | values | | | | | invalid | |
+---------------------------+-------+--------------+---------------+ | | | values | |
| H3_MISSING_SETTINGS | 0x10a | No SETTINGS | Section 8.1 | +---------------------------+--------+--------------+---------------+
| | | frame | | | H3_MISSING_SETTINGS | 0x010a | No SETTINGS | Section 8.1 |
| | | received | | | | | frame | |
+---------------------------+-------+--------------+---------------+ | | | received | |
| H3_REQUEST_REJECTED | 0x10b | Request not | Section 8.1 | +---------------------------+--------+--------------+---------------+
| | | processed | | | H3_REQUEST_REJECTED | 0x010b | Request not | Section 8.1 |
+---------------------------+-------+--------------+---------------+ | | | processed | |
| H3_REQUEST_CANCELLED | 0x10c | Data no | Section 8.1 | +---------------------------+--------+--------------+---------------+
| | | longer | | | H3_REQUEST_CANCELLED | 0x010c | Data no | Section 8.1 |
| | | needed | | | | | longer | |
+---------------------------+-------+--------------+---------------+ | | | needed | |
| H3_REQUEST_INCOMPLETE | 0x10d | Stream | Section 8.1 | +---------------------------+--------+--------------+---------------+
| | | terminated | | | H3_REQUEST_INCOMPLETE | 0x010d | Stream | Section 8.1 |
| | | early | | | | | terminated | |
+---------------------------+-------+--------------+---------------+ | | | early | |
| H3_MESSAGE_ERROR | 0x10e | Malformed | Section 8.1 | +---------------------------+--------+--------------+---------------+
| | | message | | | H3_MESSAGE_ERROR | 0x010e | Malformed | Section 8.1 |
+---------------------------+-------+--------------+---------------+ | | | message | |
| H3_CONNECT_ERROR | 0x10f | TCP reset or | Section 8.1 | +---------------------------+--------+--------------+---------------+
| | | error on | | | H3_CONNECT_ERROR | 0x010f | TCP reset | Section 8.1 |
| | | CONNECT | | | | | or error on | |
| | | request | | | | | CONNECT | |
+---------------------------+-------+--------------+---------------+ | | | request | |
| H3_VERSION_FALLBACK | 0x110 | Retry over | Section 8.1 | +---------------------------+--------+--------------+---------------+
| | | HTTP/1.1 | | | H3_VERSION_FALLBACK | 0x0110 | Retry over | Section 8.1 |
+---------------------------+-------+--------------+---------------+ | | | HTTP/1.1 | |
+---------------------------+--------+--------------+---------------+
Table 4: Initial HTTP/3 Error Codes Table 4: Initial HTTP/3 Error Codes
Each code of the format "0x1f * N + 0x21" for non-negative integer Each code of the format 0x1f * N + 0x21 for non-negative integer
values of N (that is, 0x21, 0x40, ..., through 0x3ffffffffffffffe) values of N (that is, 0x21, 0x40, ..., through 0x3ffffffffffffffe)
MUST NOT be assigned by IANA and MUST NOT appear in the listing of MUST NOT be assigned by IANA and MUST NOT appear in the listing of
assigned values. assigned values.
11.2.4. Stream Types 11.2.4. Stream Types
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 Types" registry governs a 62-bit space.
This registry follows the QUIC registry policy; see Section 11.2. This registry follows the QUIC registry policy; see Section 11.2.
Permanent registrations in this registry are assigned using the Permanent registrations in this registry are assigned using the
Specification Required policy ([RFC8126]), except for values between Specification Required policy ([RFC8126]), except for values between
0x00 and 0x3f (in hexadecimal; inclusive), which are assigned using 0x00 and 0x3f (in hexadecimal; inclusive), which are assigned using
Standards Action or IESG Approval as defined in Sections 4.9 and 4.10 Standards Action or IESG Approval as defined in Sections 4.9 and 4.10
of [RFC8126]. of [RFC8126].
In addition to common fields as described in Section 11.2, permanent In addition to common fields as described in Section 11.2, permanent
registrations in this registry MUST include the following fields: registrations in this registry MUST include the following fields:
Stream Type: A name or label for the stream type. Stream Type: A name or label for the stream type.
Sender: Which endpoint on an HTTP/3 connection may initiate a stream Sender: Which endpoint on an HTTP/3 connection may initiate a stream
of this type. Values are "Client", "Server", or "Both". of this type. Values are "Client", "Server", or "Both".
Specifications for permanent registrations MUST include a description Specifications for permanent registrations MUST include a description
of the stream type, including the layout and semantics of the stream of the stream type, including the layout and semantics of the stream
contents. contents.
The entries in the following table are registered by this document. The entries in Table 5 are registered by this document.
+================+=======+===============+========+ +================+=======+===============+========+
| Stream Type | Value | Specification | Sender | | Stream Type | Value | Specification | Sender |
+================+=======+===============+========+ +================+=======+===============+========+
| Control Stream | 0x00 | Section 6.2.1 | Both | | Control Stream | 0x00 | Section 6.2.1 | Both |
+----------------+-------+---------------+--------+ +----------------+-------+---------------+--------+
| Push Stream | 0x01 | Section 4.4 | Server | | Push Stream | 0x01 | Section 4.6 | Server |
+----------------+-------+---------------+--------+ +----------------+-------+---------------+--------+
Table 5 Table 5: Initial Stream Types
Each code of the format "0x1f * N + 0x21" for non-negative integer Each code of the format 0x1f * N + 0x21 for non-negative integer
values of N (that is, 0x21, 0x40, ..., through 0x3ffffffffffffffe) values of N (that is, 0x21, 0x40, ..., through 0x3ffffffffffffffe)
MUST NOT be assigned by IANA and MUST NOT appear in the listing of MUST NOT be assigned by IANA and MUST NOT appear in the listing of
assigned values. assigned values.
12. References 12. References
12.1. Normative References 12.1. Normative References
[ALTSVC] Nottingham, M., McManus, P., and J. Reschke, "HTTP [ALTSVC] Nottingham, M., McManus, P., and J. Reschke, "HTTP
Alternative Services", RFC 7838, DOI 10.17487/RFC7838, Alternative Services", RFC 7838, DOI 10.17487/RFC7838,
April 2016, <https://www.rfc-editor.org/info/rfc7838>. April 2016, <https://www.rfc-editor.org/info/rfc7838>.
[CACHING] Fielding, R., Nottingham, M., and J. Reschke, "HTTP [COOKIES] Barth, A., "HTTP State Management Mechanism", RFC 6265,
Caching", Work in Progress, Internet-Draft, draft-ietf- DOI 10.17487/RFC6265, April 2011,
httpbis-cache-14, 12 January 2021, <http://www.ietf.org/ <https://www.rfc-editor.org/info/rfc6265>.
internet-drafts/draft-ietf-httpbis-cache-14.txt>.
[HTTP] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/info/rfc9110>.
[HTTP-CACHING]
Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Caching", STD 98, RFC 9111,
DOI 10.17487/RFC9111, June 2022,
<https://www.rfc-editor.org/info/rfc9111>.
[HTTP-REPLAY] [HTTP-REPLAY]
Thomson, M., Nottingham, M., and W. Tarreau, "Using Early Thomson, M., Nottingham, M., and W. Tarreau, "Using Early
Data in HTTP", RFC 8470, DOI 10.17487/RFC8470, September Data in HTTP", RFC 8470, DOI 10.17487/RFC8470, September
2018, <https://www.rfc-editor.org/info/rfc8470>. 2018, <https://www.rfc-editor.org/info/rfc8470>.
[QPACK] Krasic, C., Bishop, M., and A. Frindell, Ed., "QPACK: [QPACK] Krasic, C., Bishop, M., and A. Frindell, Ed., "QPACK:
Header Compression for HTTP over QUIC", Work in Progress, Field Compression for HTTP/3", RFC 9204,
Internet-Draft, draft-ietf-quic-qpack-21, 2 February 2021, DOI 10.17487/RFC9204, June 2022,
<https://tools.ietf.org/html/draft-ietf-quic-qpack-21>. <https://www.rfc-editor.org/info/rfc9204>.
[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", Work in Progress, Multiplexed and Secure Transport", RFC 9000,
Internet-Draft, draft-ietf-quic-transport-34, 2 February DOI 10.17487/RFC9000, May 2021,
2021, <https://tools.ietf.org/html/draft-ietf-quic- <https://www.rfc-editor.org/info/rfc9000>.
transport-34>.
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, [RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981, RFC 793, DOI 10.17487/RFC0793, September 1981,
<https://www.rfc-editor.org/info/rfc793>. <https://www.rfc-editor.org/info/rfc793>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS) [RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS)
Extensions: Extension Definitions", RFC 6066, Extensions: Extension Definitions", RFC 6066,
DOI 10.17487/RFC6066, January 2011, DOI 10.17487/RFC6066, January 2011,
<https://www.rfc-editor.org/info/rfc6066>. <https://www.rfc-editor.org/info/rfc6066>.
[RFC6265] Barth, A., "HTTP State Management Mechanism", RFC 6265,
DOI 10.17487/RFC6265, April 2011,
<https://www.rfc-editor.org/info/rfc6265>.
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol "Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301, Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, <https://www.rfc-editor.org/info/rfc7301>. July 2014, <https://www.rfc-editor.org/info/rfc7301>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[SEMANTICS]
Fielding, R., Nottingham, M., and J. Reschke, "HTTP
Semantics", Work in Progress, Internet-Draft, draft-ietf-
httpbis-semantics-14, 12 January 2021,
<http://www.ietf.org/internet-drafts/draft-ietf-httpbis-
semantics-14.txt>.
[URI] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [URI] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>. <https://www.rfc-editor.org/info/rfc3986>.
12.2. Informative References 12.2. Informative References
[BREACH] Gluck, Y., Harris, N., and A. Prado, "BREACH: Reviving the [BREACH] Gluck, Y., Harris, N., and A. Prado, "BREACH: Reviving the
CRIME Attack", July 2013, CRIME Attack", July 2013,
<http://breachattack.com/resources/ <http://breachattack.com/resources/
skipping to change at page 58, line 14 skipping to change at line 2617
[DNS-TERMS] [DNS-TERMS]
Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499, Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499,
January 2019, <https://www.rfc-editor.org/info/rfc8499>. January 2019, <https://www.rfc-editor.org/info/rfc8499>.
[HPACK] Peon, R. and H. Ruellan, "HPACK: Header Compression for [HPACK] Peon, R. and H. Ruellan, "HPACK: Header Compression for
HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015, HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015,
<https://www.rfc-editor.org/info/rfc7541>. <https://www.rfc-editor.org/info/rfc7541>.
[HTTP11] Fielding, R., Nottingham, M., and J. Reschke, "HTTP/1.1", [HTTP/1.1] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Work in Progress, Internet-Draft, draft-ietf-httpbis- Ed., "HTTP/1.1", STD 99, RFC 9112, DOI 10.17487/RFC9112,
messaging-14, 12 January 2021, <http://www.ietf.org/ June 2022, <https://www.rfc-editor.org/info/rfc9112>.
internet-drafts/draft-ietf-httpbis-messaging-14.txt>.
[HTTP2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext [HTTP/2] Thomson, M., Ed. and C. Benfield, Ed., "HTTP/2", RFC 9113,
Transfer Protocol Version 2 (HTTP/2)", RFC 7540, DOI 10.17487/RFC9113, June 2022,
DOI 10.17487/RFC7540, May 2015, <https://www.rfc-editor.org/info/rfc9113>.
<https://www.rfc-editor.org/info/rfc7540>.
[RFC6585] Nottingham, M. and R. Fielding, "Additional HTTP Status [RFC6585] Nottingham, M. and R. Fielding, "Additional HTTP Status
Codes", RFC 6585, DOI 10.17487/RFC6585, April 2012, Codes", RFC 6585, DOI 10.17487/RFC6585, April 2012,
<https://www.rfc-editor.org/info/rfc6585>. <https://www.rfc-editor.org/info/rfc6585>.
[RFC8164] Nottingham, M. and M. Thomson, "Opportunistic Security for [RFC8164] Nottingham, M. and M. Thomson, "Opportunistic Security for
HTTP/2", RFC 8164, DOI 10.17487/RFC8164, May 2017, HTTP/2", RFC 8164, DOI 10.17487/RFC8164, May 2017,
<https://www.rfc-editor.org/info/rfc8164>. <https://www.rfc-editor.org/info/rfc8164>.
[TFO] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP [TFO] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP
Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014, Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014,
<https://www.rfc-editor.org/info/rfc7413>. <https://www.rfc-editor.org/info/rfc7413>.
[TLS13] Rescorla, E., "The Transport Layer Security (TLS) Protocol [TLS] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
Appendix A. Considerations for Transitioning from HTTP/2 Appendix A. Considerations for Transitioning from HTTP/2
HTTP/3 is strongly informed by HTTP/2, and bears many similarities. HTTP/3 is strongly informed by HTTP/2, and it bears many
This section describes the approach taken to design HTTP/3, points similarities. This section describes the approach taken to design
out important differences from HTTP/2, and describes how to map HTTP/3, points out important differences from HTTP/2, and describes
HTTP/2 extensions into HTTP/3. how to map HTTP/2 extensions into HTTP/3.
HTTP/3 begins from the premise that similarity to HTTP/2 is HTTP/3 begins from the premise that similarity to HTTP/2 is
preferable, but not a hard requirement. HTTP/3 departs from HTTP/2 preferable, but not a hard requirement. HTTP/3 departs from HTTP/2
where QUIC differs from TCP, either to take advantage of QUIC where QUIC differs from TCP, either to take advantage of QUIC
features (like streams) or to accommodate important shortcomings features (like streams) or to accommodate important shortcomings
(such as a lack of total ordering). These differences make HTTP/3 (such as a lack of total ordering). While HTTP/3 is similar to
similar to HTTP/2 in key aspects, such as the relationship of HTTP/2 in key aspects, such as the relationship of requests and
requests and responses to streams. However, the details of the responses to streams, the details of the HTTP/3 design are
HTTP/3 design are substantially different from HTTP/2. substantially different from HTTP/2.
Some important departures are noted in this section. Some important departures are noted in this section.
A.1. Streams A.1. Streams
HTTP/3 permits use of a larger number of streams (2^(62)-1) than HTTP/3 permits use of a larger number of streams (2^62-1) than
HTTP/2. The same considerations about exhaustion of stream HTTP/2. The same considerations about exhaustion of stream
identifier space apply, though the space is significantly larger such identifier space apply, though the space is significantly larger such
that it is likely that other limits in QUIC are reached first, such that it is likely that other limits in QUIC are reached first, such
as the limit on the connection flow control window. as the limit on the connection flow-control window.
In contrast to HTTP/2, stream concurrency in HTTP/3 is managed by In contrast to HTTP/2, stream concurrency in HTTP/3 is managed by
QUIC. QUIC considers a stream closed when all data has been received QUIC. QUIC considers a stream closed when all data has been received
and sent data has been acknowledged by the peer. HTTP/2 considers a and sent data has been acknowledged by the peer. HTTP/2 considers a
stream closed when the frame containing the END_STREAM bit has been stream closed when the frame containing the END_STREAM bit has been
committed to the transport. As a result, the stream for an committed to the transport. As a result, the stream for an
equivalent exchange could remain "active" for a longer period of equivalent exchange could remain "active" for a longer period of
time. HTTP/3 servers might choose to permit a larger number of time. HTTP/3 servers might choose to permit a larger number of
concurrent client-initiated bidirectional streams to achieve concurrent client-initiated bidirectional streams to achieve
equivalent concurrency to HTTP/2, depending on the expected usage equivalent concurrency to HTTP/2, depending on the expected usage
patterns. patterns.
In HTTP/2, only request and response bodies (the frame payload of In HTTP/2, only request and response bodies (the frame payload of
DATA frames) are subject to flow control. All HTTP/3 frames are sent DATA frames) are subject to flow control. All HTTP/3 frames are sent
on QUIC streams, so all frames on all streams are flow-controlled in on QUIC streams, so all frames on all streams are flow controlled in
HTTP/3. HTTP/3.
Due to the presence of other unidirectional stream types, HTTP/3 does Due to the presence of other unidirectional stream types, HTTP/3 does
not rely exclusively on the number of concurrent unidirectional not rely exclusively on the number of concurrent unidirectional
streams to control the number of concurrent in-flight pushes. streams to control the number of concurrent in-flight pushes.
Instead, HTTP/3 clients use the MAX_PUSH_ID frame to control the Instead, HTTP/3 clients use the MAX_PUSH_ID frame to control the
number of pushes received from an HTTP/3 server. number of pushes received from an HTTP/3 server.
A.2. HTTP Frame Types A.2. HTTP Frame Types
Many framing concepts from HTTP/2 can be elided on QUIC, because the Many framing concepts from HTTP/2 can be elided on QUIC, because the
transport deals with them. Because frames are already on a stream, transport deals with them. Because frames are already on a stream,
they can omit the stream number. Because frames do not block they can omit the stream number. Because frames do not block
multiplexing (QUIC's multiplexing occurs below this layer), the multiplexing (QUIC's multiplexing occurs below this layer), the
support for variable-maximum-length packets can be removed. Because support for variable-maximum-length packets can be removed. Because
stream termination is handled by QUIC, an END_STREAM flag is not stream termination is handled by QUIC, an END_STREAM flag is not
required. This permits the removal of the Flags field from the required. This permits the removal of the Flags field from the
generic frame layout. generic frame layout.
Frame payloads are largely drawn from [HTTP2]. However, QUIC Frame payloads are largely drawn from [HTTP/2]. However, QUIC
includes many features (e.g., flow control) that are also present in includes many features (e.g., flow control) that are also present in
HTTP/2. In these cases, the HTTP mapping does not re-implement them. HTTP/2. In these cases, the HTTP mapping does not re-implement them.
As a result, several HTTP/2 frame types are not required in HTTP/3. As a result, several HTTP/2 frame types are not required in HTTP/3.
Where an HTTP/2-defined frame is no longer used, the frame ID has Where an HTTP/2-defined frame is no longer used, the frame ID has
been reserved in order to maximize portability between HTTP/2 and been reserved in order to maximize portability between HTTP/2 and
HTTP/3 implementations. However, even frame types that appear in HTTP/3 implementations. However, even frame types that appear in
both mappings do not have identical semantics. both mappings do not have identical semantics.
Many of the differences arise from the fact that HTTP/2 provides an Many of the differences arise from the fact that HTTP/2 provides an
absolute ordering between frames across all streams, while QUIC absolute ordering between frames across all streams, while QUIC
skipping to change at page 60, line 41 skipping to change at line 2725
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. HTTP/3 does not provide a means of (optionally) in HEADERS frames. HTTP/3 does not provide a means of
signaling priority. signaling priority.
Note that while there is no explicit signaling for priority, this Note that, while there is no explicit signaling for priority, this
does not mean that prioritization is not important for achieving good does not mean that prioritization is not important for achieving good
performance. performance.
A.2.2. Field Compression Differences A.2.2. Field Compression Differences
HPACK was designed with the assumption of in-order delivery. A HPACK was designed with the assumption of in-order delivery. A
sequence of encoded field sections must arrive (and be decoded) at an sequence of encoded field sections must arrive (and be decoded) at an
endpoint in the same order in which they were encoded. This ensures endpoint in the same order in which they were encoded. This ensures
that the dynamic state at the two endpoints remains in sync. that the dynamic state at the two endpoints remains in sync.
Because this total ordering is not provided by QUIC, HTTP/3 uses a Because this total ordering is not provided by QUIC, HTTP/3 uses a
modified version of HPACK, called QPACK. QPACK uses a single modified version of HPACK, called QPACK. QPACK uses a single
unidirectional stream to make all modifications to the dynamic table, unidirectional stream to make all modifications to the dynamic table,
ensuring a total order of updates. All frames that contain encoded ensuring a total order of updates. All frames that contain encoded
fields merely reference the table state at a given time without fields merely reference the table state at a given time without
modifying it. modifying it.
[QPACK] provides additional details. [QPACK] provides additional details.
A.2.3. Flow Control Differences A.2.3. Flow-Control Differences
HTTP/2 specifies a stream flow control mechanism. Although all HTTP/2 specifies a stream flow-control mechanism. Although all
HTTP/2 frames are delivered on streams, only the DATA frame payload HTTP/2 frames are delivered on streams, only the DATA frame payload
is subject to flow control. QUIC provides flow control for stream is subject to flow control. QUIC provides flow control for stream
data and all HTTP/3 frame types defined in this document are sent on data and all HTTP/3 frame types defined in this document are sent on
streams. Therefore, all frame headers and payload are subject to streams. Therefore, all frame headers and payload are subject to
flow control. flow control.
A.2.4. Guidance for New Frame Type Definitions A.2.4. Guidance for New Frame Type Definitions
Frame type definitions in HTTP/3 often use the QUIC variable-length Frame type definitions in HTTP/3 often use the QUIC variable-length
integer encoding. In particular, Stream IDs use this encoding, which integer encoding. In particular, stream IDs use this encoding, which
allows for a larger range of possible values than the encoding used allows for a larger range of possible values than the encoding used
in HTTP/2. Some frames in HTTP/3 use an identifier other than a in HTTP/2. Some frames in HTTP/3 use an identifier other than a
Stream ID (e.g., Push IDs). Redefinition of the encoding of stream ID (e.g., push IDs). Redefinition of the encoding of
extension frame types might be necessary if the encoding includes a extension frame types might be necessary if the encoding includes a
Stream ID. stream ID.
Because the Flags field is not present in generic HTTP/3 frames, Because the Flags field is not present in generic HTTP/3 frames,
those frames that depend on the presence of flags need to allocate those frames that depend on the presence of flags need to allocate
space for flags as part of their frame payload. space for flags as part of their frame payload.
Other than these issues, frame type HTTP/2 extensions are typically Other than these issues, frame type HTTP/2 extensions are typically
portable to QUIC simply by replacing Stream 0 in HTTP/2 with a portable to QUIC simply by replacing stream 0 in HTTP/2 with a
control stream in HTTP/3. HTTP/3 extensions will not assume control stream in HTTP/3. HTTP/3 extensions will not assume
ordering, but would not be harmed by ordering, and are expected to be ordering, but would not be harmed by ordering, and are expected to be
portable to HTTP/2. portable to HTTP/2.
A.2.5. Comparison Between HTTP/2 and HTTP/3 Frame Types A.2.5. Comparison of HTTP/2 and HTTP/3 Frame Types
DATA (0x0): Padding is not defined in HTTP/3 frames. See DATA (0x00): 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 (0x01): The PRIORITY region of HEADERS is not defined in
HTTP/3 frames. Padding is not defined in HTTP/3 frames. See HTTP/3 frames. Padding is not defined in HTTP/3 frames. See
Section 7.2.2. Section 7.2.2.
PRIORITY (0x2): As described in Appendix A.2.1, HTTP/3 does not PRIORITY (0x02): As described in Appendix A.2.1, HTTP/3 does not
provide a means of signaling priority. provide a means of signaling priority.
RST_STREAM (0x3): RST_STREAM frames do not exist in HTTP/3, since RST_STREAM (0x03): RST_STREAM frames do not exist in HTTP/3, since
QUIC provides stream lifecycle management. The same code point is QUIC provides stream lifecycle management. The same code point is
used for the CANCEL_PUSH frame (Section 7.2.3). used for the CANCEL_PUSH frame (Section 7.2.3).
SETTINGS (0x4): SETTINGS frames are sent only at the beginning of SETTINGS (0x04): SETTINGS frames are sent only at the beginning of
the connection. See Section 7.2.4 and Appendix A.3. the connection. See Section 7.2.4 and Appendix A.3.
PUSH_PROMISE (0x5): The PUSH_PROMISE frame does not reference a PUSH_PROMISE (0x05): The PUSH_PROMISE frame does not reference a
stream; instead the push stream references the PUSH_PROMISE frame stream; instead, the push stream references the PUSH_PROMISE frame
using a Push ID. See Section 7.2.5. using a push ID. See Section 7.2.5.
PING (0x6): PING frames do not exist in HTTP/3, as QUIC provides PING (0x06): PING frames do not exist in HTTP/3, as QUIC provides
equivalent functionality. equivalent functionality.
GOAWAY (0x7): GOAWAY does not contain an error code. In the client GOAWAY (0x07): GOAWAY does not contain an error code. In the
to server direction, it carries a Push ID instead of a server client-to-server direction, it carries a push ID instead of a
initiated stream ID. See Section 7.2.6. server-initiated stream ID. See Section 7.2.6.
WINDOW_UPDATE (0x8): WINDOW_UPDATE frames do not exist in HTTP/3, WINDOW_UPDATE (0x08): WINDOW_UPDATE frames do not exist in HTTP/3,
since QUIC provides flow control. since QUIC provides flow control.
CONTINUATION (0x9): CONTINUATION frames do not exist in HTTP/3; CONTINUATION (0x09): CONTINUATION frames do not exist in HTTP/3;
instead, larger HEADERS/PUSH_PROMISE frames than HTTP/2 are instead, larger HEADERS/PUSH_PROMISE frames than HTTP/2 are
permitted. 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 [HTTP/2] 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 11.2.1. See Section 11.2.1.
A.3. HTTP/2 SETTINGS Parameters A.3. HTTP/2 SETTINGS Parameters
An important difference from HTTP/2 is that settings are sent once, An important difference from HTTP/2 is that settings are sent once,
as the first frame of the control stream, and thereafter cannot as the first frame of the control stream, and thereafter cannot
change. This eliminates many corner cases around synchronization of change. This eliminates many corner cases around synchronization of
changes. changes.
Some transport-level options that HTTP/2 specifies via the SETTINGS Some transport-level options that HTTP/2 specifies via the SETTINGS
frame are superseded by QUIC transport parameters in HTTP/3. The frame are superseded by QUIC transport parameters in HTTP/3. The
HTTP-level setting that is retained in HTTP/3 has the same value as HTTP-level setting that is retained in HTTP/3 has the same value as
in HTTP/2. The superseded settings are reserved, and their receipt in HTTP/2. The superseded settings are reserved, and their receipt
is an error. See Section 7.2.4.1 for discussion of both the retained is an error. See Section 7.2.4.1 for discussion of both the retained
and reserved values. and reserved values.
Below is a listing of how each HTTP/2 SETTINGS parameter is mapped: Below is a listing of how each HTTP/2 SETTINGS parameter is mapped:
SETTINGS_HEADER_TABLE_SIZE (0x1): See [QPACK]. SETTINGS_HEADER_TABLE_SIZE (0x01): See [QPACK].
SETTINGS_ENABLE_PUSH (0x2): This is removed in favor of the SETTINGS_ENABLE_PUSH (0x02): This is removed in favor of the
MAX_PUSH_ID frame, which provides a more granular control over MAX_PUSH_ID frame, which provides a more granular control over
server push. Specifying a setting with the identifier 0x2 server push. Specifying a setting with the identifier 0x02
(corresponding to the SETTINGS_ENABLE_PUSH parameter) in the (corresponding to the SETTINGS_ENABLE_PUSH parameter) in the
HTTP/3 SETTINGS frame is an error. HTTP/3 SETTINGS frame is an error.
SETTINGS_MAX_CONCURRENT_STREAMS (0x3): QUIC controls the largest SETTINGS_MAX_CONCURRENT_STREAMS (0x03): QUIC controls the largest
open Stream ID as part of its flow control logic. Specifying a open stream ID as part of its flow-control logic. Specifying a
setting with the identifier 0x3 (corresponding to the setting with the identifier 0x03 (corresponding to the
SETTINGS_MAX_CONCURRENT_STREAMS parameter) in the HTTP/3 SETTINGS SETTINGS_MAX_CONCURRENT_STREAMS parameter) in the HTTP/3 SETTINGS
frame is an error. frame is an error.
SETTINGS_INITIAL_WINDOW_SIZE (0x4): QUIC requires both stream and SETTINGS_INITIAL_WINDOW_SIZE (0x04): QUIC requires both stream and
connection flow control window sizes to be specified in the connection flow-control window sizes to be specified in the
initial transport handshake. Specifying a setting with the initial transport handshake. Specifying a setting with the
identifier 0x4 (corresponding to the SETTINGS_INITIAL_WINDOW_SIZE identifier 0x04 (corresponding to the SETTINGS_INITIAL_WINDOW_SIZE
parameter) in the HTTP/3 SETTINGS frame is an error. parameter) in the HTTP/3 SETTINGS frame is an error.
SETTINGS_MAX_FRAME_SIZE (0x5): This setting has no equivalent in SETTINGS_MAX_FRAME_SIZE (0x05): This setting has no equivalent in
HTTP/3. Specifying a setting with the identifier 0x5 HTTP/3. Specifying a setting with the identifier 0x05
(corresponding to the SETTINGS_MAX_FRAME_SIZE parameter) in the (corresponding to the SETTINGS_MAX_FRAME_SIZE parameter) in the
HTTP/3 SETTINGS frame is an error. HTTP/3 SETTINGS frame is an error.
SETTINGS_MAX_HEADER_LIST_SIZE (0x6): This setting identifier has SETTINGS_MAX_HEADER_LIST_SIZE (0x06): This setting identifier has
been renamed SETTINGS_MAX_FIELD_SECTION_SIZE. been renamed SETTINGS_MAX_FIELD_SECTION_SIZE.
In HTTP/3, setting values are variable-length integers (6, 14, 30, or In HTTP/3, setting values are variable-length integers (6, 14, 30, or
62 bits long) rather than fixed-length 32-bit fields as in HTTP/2. 62 bits long) rather than fixed-length 32-bit fields as in HTTP/2.
This will often produce a shorter encoding, but can produce a longer This will often produce a shorter encoding, but can produce a longer
encoding for settings that use the full 32-bit space. Settings encoding for settings that use the full 32-bit space. Settings
ported from HTTP/2 might choose to redefine their value to limit it ported from HTTP/2 might choose to redefine their value to limit it
to 30 bits for more efficient encoding, or to make use of the 62-bit to 30 bits for more efficient encoding or to make use of the 62-bit
space if more than 30 bits are required. space if more than 30 bits are required.
Settings need to be defined separately for HTTP/2 and HTTP/3. The Settings need to be defined separately for HTTP/2 and HTTP/3. The
IDs of settings defined in [HTTP2] have been reserved for simplicity. IDs of settings defined in [HTTP/2] have been reserved for
Note that the settings identifier space in HTTP/3 is substantially simplicity. Note that the settings identifier space in HTTP/3 is
larger (62 bits versus 16 bits), so many HTTP/3 settings have no substantially larger (62 bits versus 16 bits), so many HTTP/3
equivalent HTTP/2 code point. See Section 11.2.2. settings have no equivalent HTTP/2 code point. See Section 11.2.2.
As QUIC streams might arrive out of order, endpoints are advised not As QUIC streams might arrive out of order, endpoints are advised not
to wait for the peers' settings to arrive before responding to other to wait for the peers' settings to arrive before responding to other
streams. See Section 7.2.4.2. 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, the differences between HTTP/2 and HTTP/3 HTTP/2 provides. However, the differences between HTTP/2 and HTTP/3
mean that error codes are not directly portable between versions. mean that error codes are not directly portable between versions.
The HTTP/2 error codes defined in Section 7 of [HTTP2] logically map The HTTP/2 error codes defined in Section 7 of [HTTP/2] logically map
to the HTTP/3 error codes as follows: to the HTTP/3 error codes as follows:
NO_ERROR (0x0): H3_NO_ERROR in Section 8.1. NO_ERROR (0x00): H3_NO_ERROR in Section 8.1.
PROTOCOL_ERROR (0x1): This is mapped to H3_GENERAL_PROTOCOL_ERROR PROTOCOL_ERROR (0x01): This is mapped to H3_GENERAL_PROTOCOL_ERROR
except in cases where more specific error codes have been defined. except in cases where more specific error codes have been defined.
Such cases include H3_FRAME_UNEXPECTED, H3_MESSAGE_ERROR, and Such cases include H3_FRAME_UNEXPECTED, H3_MESSAGE_ERROR, and
H3_CLOSED_CRITICAL_STREAM defined in Section 8.1. H3_CLOSED_CRITICAL_STREAM defined in Section 8.1.
INTERNAL_ERROR (0x2): H3_INTERNAL_ERROR in Section 8.1. INTERNAL_ERROR (0x02): H3_INTERNAL_ERROR in Section 8.1.
FLOW_CONTROL_ERROR (0x3): Not applicable, since QUIC handles flow FLOW_CONTROL_ERROR (0x03): Not applicable, since QUIC handles flow
control. control.
SETTINGS_TIMEOUT (0x4): Not applicable, since no acknowledgment of SETTINGS_TIMEOUT (0x04): Not applicable, since no acknowledgment of
SETTINGS is defined. SETTINGS is defined.
STREAM_CLOSED (0x5): Not applicable, since QUIC handles stream STREAM_CLOSED (0x05): Not applicable, since QUIC handles stream
management. management.
FRAME_SIZE_ERROR (0x6): H3_FRAME_ERROR error code defined in FRAME_SIZE_ERROR (0x06): H3_FRAME_ERROR error code defined in
Section 8.1. Section 8.1.
REFUSED_STREAM (0x7): H3_REQUEST_REJECTED (in Section 8.1) is used REFUSED_STREAM (0x07): H3_REQUEST_REJECTED (in Section 8.1) is used
to indicate that a request was not processed. Otherwise, not to indicate that a request was not processed. Otherwise, not
applicable because QUIC handles stream management. applicable because QUIC handles stream management.
CANCEL (0x8): H3_REQUEST_CANCELLED in Section 8.1. CANCEL (0x08): H3_REQUEST_CANCELLED in Section 8.1.
COMPRESSION_ERROR (0x9): Multiple error codes are defined in COMPRESSION_ERROR (0x09): Multiple error codes are defined in
[QPACK]. [QPACK].
CONNECT_ERROR (0xa): H3_CONNECT_ERROR in Section 8.1. CONNECT_ERROR (0x0a): H3_CONNECT_ERROR in Section 8.1.
ENHANCE_YOUR_CALM (0xb): H3_EXCESSIVE_LOAD in Section 8.1. ENHANCE_YOUR_CALM (0x0b): H3_EXCESSIVE_LOAD in Section 8.1.
INADEQUATE_SECURITY (0xc): Not applicable, since QUIC is assumed to INADEQUATE_SECURITY (0x0c): Not applicable, since QUIC is assumed to
provide sufficient security on all connections. provide sufficient security on all connections.
HTTP_1_1_REQUIRED (0xd): H3_VERSION_FALLBACK in Section 8.1. HTTP_1_1_REQUIRED (0x0d): H3_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 11.2.3. Section 11.2.3.
A.4.1. Mapping Between HTTP/2 and HTTP/3 Errors A.4.1. Mapping between HTTP/2 and HTTP/3 Errors
An intermediary that converts between HTTP/2 and HTTP/3 may encounter An intermediary that converts between HTTP/2 and HTTP/3 may encounter
error conditions from either upstream. It is useful to communicate error conditions from either upstream. It is useful to communicate
the occurrence of error to the downstream but error codes largely the occurrence of errors to the downstream, but error codes largely
reflect connection-local problems that generally do not make sense to reflect connection-local problems that generally do not make sense to
propagate. propagate.
An intermediary that encounters an error from an upstream origin can An intermediary that encounters an error from an upstream origin can
indicate this by sending an HTTP status code such as 502, which is indicate this by sending an HTTP status code such as 502 (Bad
suitable for a broad class of errors. Gateway), which is suitable for a broad class of errors.
There are some rare cases where it is beneficial to propagate the There are some rare cases where it is beneficial to propagate the
error by mapping it to the closest matching error type to the error by mapping it to the closest matching error type to the
receiver. For example, an intermediary that receives an HTTP/2 receiver. For example, an intermediary that receives an HTTP/2
stream error of type REFUSED_STREAM from the origin has a clear stream error of type REFUSED_STREAM from the origin has a clear
signal that the request was not processed and that the request is signal that the request was not processed and that the request is
safe to retry. Propagating this error condition to the client as an safe to retry. Propagating this error condition to the client as an
HTTP/3 stream error of type H3_REQUEST_REJECTED allows the client to HTTP/3 stream error of type H3_REQUEST_REJECTED allows the client to
take the action it deems most appropriate. In the reverse direction, take the action it deems most appropriate. In the reverse direction,
the intermediary might deem it beneficial to pass on client request the intermediary might deem it beneficial to pass on client request
cancellations that are indicated by terminating a stream with cancellations that are indicated by terminating a stream with
H3_REQUEST_CANCELLED; see Section 4.1.2. H3_REQUEST_CANCELLED; see Section 4.1.1.
Conversion between errors is described in the logical mapping. The Conversion between errors is described in the logical mapping. The
error codes are defined in non-overlapping spaces in order to protect error codes are defined in non-overlapping spaces in order to protect
against accidental conversion that could result in the use of against accidental conversion that could result in the use of
inappropriate or unknown error codes for the target version. An inappropriate or unknown error codes for the target version. An
intermediary is permitted to promote stream errors to connection intermediary is permitted to promote stream errors to connection
errors but they should be aware of the cost to the HTTP/3 connection errors but they should be aware of the cost to the HTTP/3 connection
for what might be a temporary or intermittent error. for what might be a temporary or intermittent error.
Appendix B. Change Log
*RFC Editor's Note:* Please remove this section prior to
publication of a final version of this document.
B.1. Since draft-ietf-quic-http-32
* Removed draft version guidance; added final version string
* Added H3_MESSAGE_ERROR for malformed messages
B.2. Since draft-ietf-quic-http-31
Editorial changes only.
B.3. Since draft-ietf-quic-http-30
Editorial changes only.
B.4. Since draft-ietf-quic-http-29
* Require a connection error if a reserved frame type that
corresponds to a frame in HTTP/2 is received (#3991, #3993)
* Require a connection error if a reserved setting that corresponds
to a setting in HTTP/2 is received (#3954, #3955)
B.5. Since draft-ietf-quic-http-28
* CANCEL_PUSH is recommended even when the stream is reset (#3698,
#3700)
* Use H3_ID_ERROR when GOAWAY contains a larger identifier (#3631,
#3634)
B.6. Since draft-ietf-quic-http-27
* Updated text to refer to latest HTTP revisions
* Use the HTTP definition of authority for establishing and
coalescing connections (#253, #2223, #3558)
* Define use of GOAWAY from both endpoints (#2632, #3129)
* Require either :authority or Host if the URI scheme has a
mandatory authority component (#3408, #3475)
B.7. Since draft-ietf-quic-http-26
* No changes
B.8. Since draft-ietf-quic-http-25
* Require QUICv1 for HTTP/3 (#3117, #3323)
* Remove DUPLICATE_PUSH and allow duplicate PUSH_PROMISE (#3275,
#3309)
* Clarify the definition of "malformed" (#3352, #3345)
B.9. Since draft-ietf-quic-http-24
* Removed H3_EARLY_RESPONSE error code; H3_NO_ERROR is recommended
instead (#3130,#3208)
* Unknown error codes are equivalent to H3_NO_ERROR (#3276,#3331)
* Some error codes are reserved for greasing (#3325,#3360)
B.10. Since draft-ietf-quic-http-23
* Removed "quic" Alt-Svc parameter (#3061,#3118)
* Clients need not persist unknown settings for use in 0-RTT
(#3110,#3113)
* Clarify error cases around CANCEL_PUSH (#2819,#3083)
B.11. Since draft-ietf-quic-http-22
* Removed priority signaling (#2922,#2924)
* Further changes to error codes (#2662,#2551):
- Error codes renumbered
- HTTP_MALFORMED_FRAME replaced by HTTP_FRAME_ERROR,
HTTP_ID_ERROR, and others
* Clarify how unknown frame types interact with required frame
sequence (#2867,#2858)
* Describe interactions with the transport in terms of defined
interface terms (#2857,#2805)
* Require the use of the "http-opportunistic" resource (RFC 8164)
when scheme is "http" (#2439,#2973)
* Settings identifiers cannot be duplicated (#2979)
* 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
* Clarify that Upgrade and the 101 status code are prohibited
(#2898,#2889)
* 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)
* Unknown error codes cannot be treated as errors (#2998,#2816)
B.12. Since draft-ietf-quic-http-21
No changes
B.13. Since draft-ietf-quic-http-20
* Prohibit closing the control stream (#2509, #2666)
* Change default priority to use an orphan node (#2502, #2690)
* Exclusive priorities are restored (#2754, #2781)
* Restrict use of frames when using CONNECT (#2229, #2702)
* Close and maybe reset streams if a connection error occurs for
CONNECT (#2228, #2703)
* Encourage provision of sufficient unidirectional streams for QPACK
(#2100, #2529, #2762)
* Allow extensions to use server-initiated bidirectional streams
(#2711, #2773)
* Clarify use of maximum header list size setting (#2516, #2774)
* Extensive changes to error codes and conditions of their sending
- Require connection errors for more error conditions (#2511,
#2510)
- Updated the error codes for illegal GOAWAY frames (#2714,
#2707)
- Specified error code for HEADERS on control stream (#2708)
- Specified error code for servers receiving PUSH_PROMISE (#2709)
- Specified error code for receiving DATA before HEADERS (#2715)
- Describe malformed messages and their handling (#2410, #2764)
- Remove HTTP_PUSH_ALREADY_IN_CACHE error (#2812, #2813)
- Refactor Push ID related errors (#2818, #2820)
- Rationalize HTTP/3 stream creation errors (#2821, #2822)
B.14. Since draft-ietf-quic-http-19
* SETTINGS_NUM_PLACEHOLDERS is 0x9 (#2443,#2530)
* Non-zero bits in the Empty field of the PRIORITY frame MAY be
treated as an error (#2501)
B.15. Since draft-ietf-quic-http-18
* Resetting streams following a GOAWAY is recommended, but not
required (#2256,#2457)
* Use variable-length integers throughout (#2437,#2233,#2253,#2275)
- Variable-length frame types, stream types, and settings
identifiers
- Renumbered stream type assignments
- Modified associated reserved values
* Frame layout switched from Length-Type-Value to Type-Length-Value
(#2395,#2235)
* Specified error code for servers receiving DUPLICATE_PUSH (#2497)
* Use connection error for invalid PRIORITY (#2507, #2508)
B.16. Since draft-ietf-quic-http-17
* HTTP_REQUEST_REJECTED is used to indicate a request can be retried
(#2106, #2325)
* Changed error code for GOAWAY on the wrong stream (#2231, #2343)
B.17. Since draft-ietf-quic-http-16
* Rename "HTTP/QUIC" to "HTTP/3" (#1973)
* Changes to PRIORITY frame (#1865, #2075)
- Permitted as first frame of request streams
- Remove exclusive reprioritization
- Changes to Prioritized Element Type bits
* Define DUPLICATE_PUSH frame to refer to another PUSH_PROMISE
(#2072)
* Set defaults for settings, allow request before receiving SETTINGS
(#1809, #1846, #2038)
* Clarify message processing rules for streams that aren't closed
(#1972, #2003)
* Removed reservation of error code 0 and moved HTTP_NO_ERROR to
this value (#1922)
* Removed prohibition of zero-length DATA frames (#2098)
B.18. Since draft-ietf-quic-http-15
Substantial editorial reorganization; no technical changes.
B.19. Since draft-ietf-quic-http-14
* Recommend sensible values for QUIC transport parameters
(#1720,#1806)
* Define error for missing SETTINGS frame (#1697,#1808)
* Setting values are variable-length integers (#1556,#1807) and do
not have separate maximum values (#1820)
* Expanded discussion of connection closure (#1599,#1717,#1712)
* HTTP_VERSION_FALLBACK falls back to HTTP/1.1 (#1677,#1685)
B.20. Since draft-ietf-quic-http-13
* Reserved some frame types for grease (#1333, #1446)
* Unknown unidirectional stream types are tolerated, not errors;
some reserved for grease (#1490, #1525)
* Require settings to be remembered for 0-RTT, prohibit reductions
(#1541, #1641)
* Specify behavior for truncated requests (#1596, #1643)
B.21. Since draft-ietf-quic-http-12
* TLS SNI extension isn't mandatory if an alternative method is used
(#1459, #1462, #1466)
* Removed flags from HTTP/3 frames (#1388, #1398)
* Reserved frame types and settings for use in preserving
extensibility (#1333, #1446)
* Added general error code (#1391, #1397)
* Unidirectional streams carry a type byte and are extensible
(#910,#1359)
* Priority mechanism now uses explicit placeholders to enable
persistent structure in the tree (#441,#1421,#1422)
B.22. Since draft-ietf-quic-http-11
* Moved QPACK table updates and acknowledgments to dedicated streams
(#1121, #1122, #1238)
B.23. Since draft-ietf-quic-http-10
* Settings need to be remembered when attempting and accepting 0-RTT
(#1157, #1207)
B.24. Since draft-ietf-quic-http-09
* Selected QCRAM for header compression (#228, #1117)
* The server_name TLS extension is now mandatory (#296, #495)
* Specified handling of unsupported versions in Alt-Svc (#1093,
#1097)
B.25. Since draft-ietf-quic-http-08
* Clarified connection coalescing rules (#940, #1024)
B.26. Since draft-ietf-quic-http-07
* Changes for integer encodings in QUIC (#595,#905)
* Use unidirectional streams as appropriate (#515, #240, #281, #886)
* Improvement to the description of GOAWAY (#604, #898)
* Improve description of server push usage (#947, #950, #957)
B.27. Since draft-ietf-quic-http-06
* Track changes in QUIC error code usage (#485)
B.28. Since draft-ietf-quic-http-05
* Made push ID sequential, add MAX_PUSH_ID, remove
SETTINGS_ENABLE_PUSH (#709)
* Guidance about keep-alive and QUIC PINGs (#729)
* Expanded text on GOAWAY and cancellation (#757)
B.29. Since draft-ietf-quic-http-04
* Cite RFC 5234 (#404)
* Return to a single stream per request (#245,#557)
* Use separate frame type and settings registries from HTTP/2 (#81)
* SETTINGS_ENABLE_PUSH instead of SETTINGS_DISABLE_PUSH (#477)
* Restored GOAWAY (#696)
* Identify server push using Push ID rather than a stream ID
(#702,#281)
* DATA frames cannot be empty (#700)
B.30. Since draft-ietf-quic-http-03
None.
B.31. Since draft-ietf-quic-http-02
* Track changes in transport draft
B.32. Since draft-ietf-quic-http-01
* SETTINGS changes (#181):
- SETTINGS can be sent only once at the start of a connection; no
changes thereafter
- SETTINGS_ACK removed
- Settings can only occur in the SETTINGS frame a single time
- Boolean format updated
* Alt-Svc parameter changed from "v" to "quic"; format updated
(#229)
* Closing the connection control stream or any message control
stream is a fatal error (#176)
* HPACK Sequence counter can wrap (#173)
* 0-RTT guidance added
* Guide to differences from HTTP/2 and porting HTTP/2 extensions
added (#127,#242)
B.33. Since draft-ietf-quic-http-00
* Changed "HTTP/2-over-QUIC" to "HTTP/QUIC" throughout (#11,#29)
* Changed from using HTTP/2 framing within Stream 3 to new framing
format and two-stream-per-request model (#71,#72,#73)
* Adopted SETTINGS format from draft-bishop-httpbis-extended-
settings-01
* Reworked SETTINGS_ACK to account for indeterminate inter-stream
order (#75)
* Described CONNECT pseudo-method (#95)
* Updated ALPN token and Alt-Svc guidance (#13,#87)
* Application-layer-defined error codes (#19,#74)
B.34. Since draft-shade-quic-http2-mapping-00
* Adopted as base for draft-ietf-quic-http
* Updated authors/editors list
Acknowledgments Acknowledgments
The original authors of this specification were Robbie Shade and Mike Robbie Shade and Mike Warres were the authors of draft-shade-quic-
Warres. http2-mapping, a precursor of this document.
The IETF QUIC Working Group received an enormous amount of support The IETF QUIC Working Group received an enormous amount of support
from many people. Among others, the following people provided from many people. Among others, the following people provided
substantial contributions to this document: substantial contributions to this document:
* Bence Beky * Bence Beky
* Daan De Meyer * Daan De Meyer
* Martin Duke * Martin Duke
* Roy Fielding * Roy Fielding
* Alan Frindell * Alan Frindell
* Alessandro Ghedini * Alessandro Ghedini
* Nick Harper * Nick Harper
* Ryan Hamilton * Ryan Hamilton
* Christian Huitema * Christian Huitema
* Subodh Iyengar * Subodh Iyengar
* Robin Marx * Robin Marx
* Patrick McManus * Patrick McManus
* Luca Niccolini * Luca Niccolini
* 奥 一穂 (Kazuho Oku) * 奥 一穂 (Kazuho Oku)
* Lucas Pardue * Lucas Pardue
* Roberto Peon * Roberto Peon
* Julian Reschke * Julian Reschke
* Eric Rescorla * Eric Rescorla
* Martin Seemann * Martin Seemann
* Ben Schwartz * Ben Schwartz
* Ian Swett * Ian Swett
* Willy Taureau * Willy Taureau
* Martin Thomson * Martin Thomson
* Dmitri Tikhonov * Dmitri Tikhonov
* Tatsuhiro Tsujikawa * Tatsuhiro Tsujikawa
A portion of Mike's contribution was supported by Microsoft during A portion of Mike Bishop's contribution was supported by Microsoft
his employment there. during his employment there.
Index
C D G H M P R S
C
CANCEL_PUSH Section 2, Paragraph 5; Section 4.6, Paragraph 6;
Section 4.6, Paragraph 10; Table 1; *_Section 7.2.3_*;
Section 7.2.5, Paragraph 4.2.1; Section 7.2.7, Paragraph 1;
Table 2; Appendix A.2.5, Paragraph 1.8.1
connection error Section 2.2; Section 4.1, Paragraph 7;
Section 4.1, Paragraph 8; Section 4.4, Paragraph 8;
Section 4.4, Paragraph 10; Section 4.6, Paragraph 3;
Section 5.2, Paragraph 7; Section 6.1, Paragraph 3;
Section 6.2, Paragraph 7; Section 6.2.1, Paragraph 2;
Section 6.2.1, Paragraph 2; Section 6.2.1, Paragraph 2;
Section 6.2.2, Paragraph 3; Section 6.2.2, Paragraph 6;
Section 7.1, Paragraph 5; Section 7.1, Paragraph 6;
Section 7.2.1, Paragraph 2; Section 7.2.2, Paragraph 3;
Section 7.2.3, Paragraph 5; Section 7.2.3, Paragraph 7;
Section 7.2.3, Paragraph 8; Section 7.2.4, Paragraph 2;
Section 7.2.4, Paragraph 3; Section 7.2.4, Paragraph 6;
Section 7.2.4.1, Paragraph 5; Section 7.2.4.2, Paragraph 8;
Section 7.2.4.2, Paragraph 8; Section 7.2.5, Paragraph 5;
Section 7.2.5, Paragraph 6; Section 7.2.5, Paragraph 8;
Section 7.2.5, Paragraph 9; Section 7.2.6, Paragraph 3;
Section 7.2.6, Paragraph 5; Section 7.2.7, Paragraph 2;
Section 7.2.7, Paragraph 3; Section 7.2.7, Paragraph 6;
Section 7.2.8, Paragraph 3; *_Section 8_*; Section 10.5,
Paragraph 7; Appendix A.4.1, Paragraph 4
control stream Section 2, Paragraph 3; Section 3.2, Paragraph
4; Section 6.2, Paragraph 3; Section 6.2, Paragraph 5;
Section 6.2, Paragraph 6; *_Section 6.2.1_*; Section 7,
Paragraph 1; Section 7.2.1, Paragraph 2; Section 7.2.2,
Paragraph 3; Section 7.2.3, Paragraph 5; Section 7.2.3,
Paragraph 5; Section 7.2.4, Paragraph 2; Section 7.2.4,
Paragraph 2; Section 7.2.4, Paragraph 3; Section 7.2.5,
Paragraph 8; Section 7.2.6, Paragraph 3; Section 7.2.6,
Paragraph 5; Section 7.2.7, Paragraph 2; Section 8.1,
Paragraph 2.22.1; Section 9, Paragraph 4; Appendix A.2.4,
Paragraph 3; Appendix A.3, Paragraph 1
D
DATA Section 2, Paragraph 3; Section 4.1, Paragraph 5, Item 2;
Section 4.1, Paragraph 7; Section 4.1, Paragraph 7;
Section 4.1.2, Paragraph 3; Section 4.1.2, Paragraph 3;
Section 4.4, Paragraph 7; Section 4.4, Paragraph 7;
Section 4.4, Paragraph 7; Section 4.4, Paragraph 7;
Section 4.4, Paragraph 8; Section 4.6, Paragraph 12;
Table 1; *_Section 7.2.1_*; Table 2; Appendix A.1, Paragraph
3; Appendix A.2.3, Paragraph 1; Appendix A.2.5
G
GOAWAY Section 3.3, Paragraph 5; Section 5.2, Paragraph 1;
Section 5.2, Paragraph 1; Section 5.2, Paragraph 1;
Section 5.2, Paragraph 2; Section 5.2, Paragraph 2;
Section 5.2, Paragraph 3; Section 5.2, Paragraph 5.1.1;
Section 5.2, Paragraph 5.1.1; Section 5.2, Paragraph 5.1.2;
Section 5.2, Paragraph 5.1.2; Section 5.2, Paragraph 5, Item
2; Section 5.2, Paragraph 5, Item 2; Section 5.2, Paragraph
6; Section 5.2, Paragraph 6; Section 5.2, Paragraph 7;
Section 5.2, Paragraph 7; Section 5.2, Paragraph 8;
Section 5.2, Paragraph 8; Section 5.2, Paragraph 9;
Section 5.2, Paragraph 9; Section 5.2, Paragraph 10;
Section 5.2, Paragraph 12; Section 5.3, Paragraph 2;
Section 5.3, Paragraph 2; Section 5.4, Paragraph 2; Table 1;
*_Section 7.2.6_*; Table 2; Appendix A.2.5; Appendix A.2.5,
Paragraph 1.16.1
H
H3_CLOSED_CRITICAL_STREAM Section 6.2.1, Paragraph 2;
Section 8.1; Table 4; Appendix A.4, Paragraph 3.4.1
H3_CONNECT_ERROR Section 4.4, Paragraph 10; Section 8.1;
Table 4; Appendix A.4, Paragraph 3.22.1
H3_EXCESSIVE_LOAD Section 8.1; Section 10.5, Paragraph 7;
Table 4; Appendix A.4, Paragraph 3.24.1
H3_FRAME_ERROR Section 7.1, Paragraph 5; Section 7.1,
Paragraph 6; Section 8.1; Table 4; Appendix A.4, Paragraph
3.14.1
H3_FRAME_UNEXPECTED Section 4.1, Paragraph 7; Section 4.1,
Paragraph 8; Section 4.4, Paragraph 8; Section 7.2.1,
Paragraph 2; Section 7.2.2, Paragraph 3; Section 7.2.3,
Paragraph 5; Section 7.2.4, Paragraph 2; Section 7.2.4,
Paragraph 3; Section 7.2.5, Paragraph 8; Section 7.2.5,
Paragraph 9; Section 7.2.6, Paragraph 5; Section 7.2.7,
Paragraph 2; Section 7.2.7, Paragraph 3; Section 7.2.8,
Paragraph 3; Section 8.1; Table 4; Appendix A.4, Paragraph
3.4.1
H3_GENERAL_PROTOCOL_ERROR Section 7.2.5, Paragraph 6;
Section 8.1; Table 4; Appendix A.4, Paragraph 3.4.1
H3_ID_ERROR Section 4.6, Paragraph 3; Section 5.2, Paragraph
7; Section 6.2.2, Paragraph 6; Section 7.2.3, Paragraph 7;
Section 7.2.3, Paragraph 8; Section 7.2.5, Paragraph 5;
Section 7.2.6, Paragraph 3; Section 7.2.7, Paragraph 6;
Section 8.1; Table 4
H3_INTERNAL_ERROR Section 8.1; Table 4; Appendix A.4,
Paragraph 3.6.1
H3_MESSAGE_ERROR Section 4.1.2, Paragraph 4; Section 8.1;
Table 4; Appendix A.4, Paragraph 3.4.1
H3_MISSING_SETTINGS Section 6.2.1, Paragraph 2; Section 8.1;
Table 4
H3_NO_ERROR Section 4.1, Paragraph 15; Section 5.2, Paragraph
11; Section 6.2.3, Paragraph 2; Section 8, Paragraph 5;
Section 8.1; Section 8.1, Paragraph 3; Section 8.1,
Paragraph 3; Table 4; Appendix A.4, Paragraph 3.2.1
H3_REQUEST_CANCELLED Section 4.1.1, Paragraph 4;
Section 4.1.1, Paragraph 5; Section 4.6, Paragraph 14;
Section 7.2.3, Paragraph 3; Section 7.2.3, Paragraph 4;
Section 8.1; Table 4; Appendix A.4, Paragraph 3.18.1;
Appendix A.4.1, Paragraph 3
H3_REQUEST_INCOMPLETE Section 4.1, Paragraph 14; Section 8.1;
Table 4
H3_REQUEST_REJECTED Section 4.1.1, Paragraph 3; Section 4.1.1,
Paragraph 4; Section 4.1.1, Paragraph 5; Section 4.1.1,
Paragraph 5; Section 8.1; Table 4; Appendix A.4, Paragraph
3.16.1; Appendix A.4.1, Paragraph 3
H3_SETTINGS_ERROR Section 7.2.4, Paragraph 6; Section 7.2.4.1,
Paragraph 5; Section 7.2.4.2, Paragraph 8; Section 7.2.4.2,
Paragraph 8; Section 8.1; Table 4
H3_STREAM_CREATION_ERROR Section 6.1, Paragraph 3;
Section 6.2, Paragraph 7; Section 6.2.1, Paragraph 2;
Section 6.2.2, Paragraph 3; Section 8.1; Table 4
H3_VERSION_FALLBACK Section 8.1; Table 4; Appendix A.4,
Paragraph 3.28.1
HEADERS Section 2, Paragraph 3; Section 4.1, Paragraph 5, Item
1; Section 4.1, Paragraph 5, Item 3; Section 4.1, Paragraph
7; Section 4.1, Paragraph 7; Section 4.1, Paragraph 7;
Section 4.1, Paragraph 10; Section 4.4, Paragraph 6;
Section 4.6, Paragraph 12; Table 1; *_Section 7.2.2_*;
Section 9, Paragraph 5; Table 2; Appendix A.2.1, Paragraph
1; Appendix A.2.5; Appendix A.2.5, Paragraph 1.4.1;
Appendix A.2.5, Paragraph 1.20.1
M
malformed Section 4.1, Paragraph 3; *_Section 4.1.2_*;
Section 4.2, Paragraph 2; Section 4.2, Paragraph 3;
Section 4.2, Paragraph 5; Section 4.3, Paragraph 3;
Section 4.3, Paragraph 4; Section 4.3.1, Paragraph 5;
Section 4.3.2, Paragraph 1; Section 4.4, Paragraph 5;
Section 8.1, Paragraph 2.30.1; Section 10.3, Paragraph 1;
Section 10.3, Paragraph 2; Section 10.5.1, Paragraph 2
MAX_PUSH_ID Section 2, Paragraph 5; Section 4.6, Paragraph 3;
Section 4.6, Paragraph 3; Section 4.6, Paragraph 3;
Section 4.6, Paragraph 3; Table 1; Section 7.2.5, Paragraph
5; *_Section 7.2.7_*; Table 2; Appendix A.1, Paragraph 4;
Appendix A.3, Paragraph 4.4.1
P
push ID *_Section 4.6_*; Section 5.2, Paragraph 1;
Section 5.2, Paragraph 5, Item 2; Section 5.2, Paragraph 9;
Section 6.2.2, Paragraph 2; Section 6.2.2, Paragraph 6;
Section 6.2.2, Paragraph 6; Section 7.2.3, Paragraph 1;
Section 7.2.3, Paragraph 7; Section 7.2.3, Paragraph 7;
Section 7.2.3, Paragraph 8; Section 7.2.3, Paragraph 8;
Section 7.2.5, Paragraph 4.2.1; Section 7.2.5, Paragraph 5;
Section 7.2.5, Paragraph 5; Section 7.2.5, Paragraph 6;
Section 7.2.5, Paragraph 6; Section 7.2.5, Paragraph 7;
Section 7.2.5, Paragraph 7; Section 7.2.5, Paragraph 7;
Section 7.2.6, Paragraph 4; Section 7.2.7, Paragraph 1;
Section 7.2.7, Paragraph 4; Section 7.2.7, Paragraph 4;
Section 7.2.7, Paragraph 6; Section 7.2.7, Paragraph 6;
Section 8.1, Paragraph 2.18.1; Appendix A.2.5, Paragraph
1.12.1; Appendix A.2.5, Paragraph 1.16.1
push stream Section 4.1, Paragraph 8; Section 4.1, Paragraph
9; Section 4.6, Paragraph 3; Section 4.6, Paragraph 5;
Section 4.6, Paragraph 5; Section 4.6, Paragraph 13;
Section 4.6, Paragraph 13; Section 4.6, Paragraph 13;
Section 6.2, Paragraph 3; *_Section 6.2.2_*; Section 7,
Paragraph 1; Section 7.2.2, Paragraph 3; Section 7.2.3,
Paragraph 1; Section 7.2.3, Paragraph 2; Section 7.2.3,
Paragraph 2; Section 7.2.3, Paragraph 2; Section 7.2.3,
Paragraph 2; Section 7.2.3, Paragraph 3; Section 7.2.3,
Paragraph 4; Section 7.2.3, Paragraph 4; Section 7.2.3,
Paragraph 4; Section 7.2.5, Paragraph 4.2.1; Section 7.2.7,
Paragraph 1; Appendix A.2.5, Paragraph 1.12.1
PUSH_PROMISE Section 2, Paragraph 5; Section 4.1, Paragraph 8;
Section 4.1, Paragraph 8; Section 4.1, Paragraph 8;
Section 4.1, Paragraph 8; Section 4.1, Paragraph 10;
Section 4.6, Paragraph 4; Section 4.6, Paragraph 10;
Section 4.6, Paragraph 11; Section 4.6, Paragraph 11;
Section 4.6, Paragraph 12; Section 4.6, Paragraph 12;
Section 4.6, Paragraph 13; Section 4.6, Paragraph 13;
Section 4.6, Paragraph 13; Table 1; Section 7.2.3, Paragraph
8; Section 7.2.3, Paragraph 8; *_Section 7.2.5_*;
Section 7.2.7, Paragraph 1; Section 10.4, Paragraph 1;
Section 10.5, Paragraph 2; Table 2; Appendix A.2.5;
Appendix A.2.5, Paragraph 1.12.1; Appendix A.2.5, Paragraph
1.12.1; Appendix A.2.5, Paragraph 1.20.1
R
request stream Section 4.1, Paragraph 1; Section 4.1,
Paragraph 15; Section 4.1, Paragraph 15; Section 4.1.1,
Paragraph 1; Section 4.1.1, Paragraph 5; Section 4.4,
Paragraph 5; Section 4.4, Paragraph 9; Section 4.6,
Paragraph 4; Section 4.6, Paragraph 4; Section 4.6,
Paragraph 11; Section 4.6, Paragraph 11; *_Section 6.1_*;
Section 7, Paragraph 1; Section 7.2.2, Paragraph 3;
Section 7.2.5, Paragraph 1
S
SETTINGS Section 3.2, Paragraph 4; Section 3.2, Paragraph 4;
Section 6.2.1, Paragraph 2; Table 1; Section 7, Paragraph 3;
*_Section 7.2.4_*; Section 8.1, Paragraph 2.20.1;
Section 8.1, Paragraph 2.22.1; Section 9, Paragraph 4;
Section 10.5, Paragraph 4; Table 2; Table 4; Table 4;
Appendix A.2.5; Appendix A.2.5, Paragraph 1.10.1;
Appendix A.3, Paragraph 2; Appendix A.3, Paragraph 3;
Appendix A.3, Paragraph 4.4.1; Appendix A.3, Paragraph
4.6.1; Appendix A.3, Paragraph 4.8.1; Appendix A.3,
Paragraph 4.10.1; Appendix A.4, Paragraph 3.10.1
SETTINGS_MAX_FIELD_SECTION_SIZE Section 4.2.2, Paragraph 2;
Section 7.2.4.1; Section 10.5.1, Paragraph 2; Appendix A.3,
Paragraph 4.12.1
stream error Section 2.2; Section 4.1.2, Paragraph 4;
Section 4.4, Paragraph 10; *_Section 8_*; Appendix A.4.1,
Paragraph 3; Appendix A.4.1, Paragraph 3; Appendix A.4.1,
Paragraph 4
Author's Address Author's Address
Mike Bishop (editor) Mike Bishop (editor)
Akamai Akamai
Email: mbishop@evequefou.be Email: mbishop@evequefou.be
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