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ART HTTP extended connect 42 The mechanism for running the WebSocket Protocol over a single stream of an HTTP/2 connection is equally applicable to HTTP/3, but the HTTP-version-specific details need to be specified. This document describes how the mechanism is adapted for HTTP/3. Status information for this document may be found at . Discussion of this document takes place on the HTTP Working Group mailing list (), which is archived at . Working Group information can be found at . Source for this draft and an issue tracker can be found at .

Introduction "Bootstrapping WebSockets with HTTP/2" defines an extension to HTTP/2 that is also useful in HTTP/3 . This extension makes use of an HTTP/2 setting. gives some guidance on what changes (if any) are appropriate when porting settings from HTTP/2 to HTTP/3.

Conventions and Definitions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

WebSockets Upgrade over HTTP/3 defines a mechanism for running the WebSocket Protocol over a single stream of an HTTP/2 connection. It defines an Extended CONNECT method that specifies a new ":protocol" pseudo-header field and new semantics for the ":path" and ":authority" pseudo-header fields. It also defines a new HTTP/2 setting sent by a server to allow the client to use Extended CONNECT. The semantics of the pseudo-header fields and setting are identical to those in HTTP/2 as defined in . requires that HTTP/3 settings be registered separately for HTTP/3. The SETTINGS_ENABLE_CONNECT_PROTOCOL value is 0x08 (decimal 8), as in HTTP/2. If a server advertises support for Extended CONNECT but receives an Extended CONNECT request with a ":protocol" value that is unknown or is not supported, the server SHOULD respond to the request with a 501 (Not Implemented) status code (). A server MAY provide more information via a "problem details" response . The HTTP/3 stream closure is also analogous to the TCP connection closure of . Orderly TCP-level closures are represented as a FIN bit on the stream (). RST exceptions are represented with a stream error () of type H3_REQUEST_CANCELLED ().

Security Considerations This document introduces no new security considerations beyond those discussed in .

IANA Considerations This document registers a new setting in the "HTTP/3 Settings" registry ().

Value:

0x08

Setting Name:

SETTINGS_ENABLE_CONNECT_PROTOCOL

Default:

0

Status:

permanent

Specification:

This document

Change Controller:

IETF

Contact:

HTTP Working Group (ietf-http-wg@w3.org)

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Acknowledgments This document had reviews and input from many contributors in the IETF HTTP and QUIC Working Groups, with substantive input from David Schinazi, Martin Thomson, Lucas Pardue, Mike Bishop, Dragana Damjanovic, Mark Nottingham, and Julian Reschke.