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net/http: add HTTP2Config.EnableConnectProtocol#79300

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@tigrato tigrato commented May 9, 2026 •
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net/http: add HTTP2Config.EnableConnectProtocol

Introduce EnableConnectProtocol to HTTP2Config, allowing HTTP/2
servers to opt in to advertising Extended CONNECT support (RFC 8441)
on a per-server basis.

Extended CONNECT was disabled by default in Go 1.24 because browsers
interpret SETTINGS_ENABLE_CONNECT_PROTOCOL as implicit
WebSocket-over-HTTP/2 support, which breaks servers whose WebSocket
implementation does not support it (see #71128). EnableConnectProtocol
provides the knob needed for WebSocket layers that do support Extended
CONNECT to re-enable it without requiring GODEBUG=http2xconnect=1.
This is a problem because http2xconnect is not accessible via the
//go:debug directive.

When enabled, HTTP/2 servers advertise SETTINGS_ENABLE_CONNECT_PROTOCOL
in the initial SETTINGS frame. Incoming CONNECT requests that carry a
:protocol pseudo-header are forwarded to the handler with that value
accessible via r.Header.Get(":protocol").

The legacy disableExtendedConnectProtocol package variable and its
GODEBUG knob are preserved for backwards compatibility.

For #53208.
For #71128.

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gopherbot commented May 9, 2026

This PR (HEAD: e5bde2b) has been imported to Gerrit for code review.

Please visit Gerrit at https://go-review.googlesource.com/c/go/+/776300.

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@tigrato
net/http: add HTTP2Config.EnableConnectProtocol
616345e 
Introduce EnableConnectProtocol to HTTP2Config, allowing HTTP/2
servers to opt in to advertising Extended CONNECT support (RFC 8441)
on a per-server basis.

Extended CONNECT was disabled by default in Go 1.24 because browsers
interpret SETTINGS_ENABLE_CONNECT_PROTOCOL as implicit
WebSocket-over-HTTP/2 support, which breaks servers whose WebSocket
implementation does not support it (see golang#71128). EnableConnectProtocol
provides the knob needed for WebSocket layers that do support Extended
CONNECT to re-enable it without requiring GODEBUG=http2xconnect=1.
This is a problem because http2xconnect is not accessible via the
//go:debug directive.

When enabled, HTTP/2 servers advertise SETTINGS_ENABLE_CONNECT_PROTOCOL
in the initial SETTINGS frame. Incoming CONNECT requests that carry a
:protocol pseudo-header are forwarded to the handler with that value
accessible via r.Header.Get(":protocol").

The legacy disableExtendedConnectProtocol package variable and its
GODEBUG knob are preserved for backwards compatibility.

For golang#53208.
For golang#71128.
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gopherbot commented May 9, 2026

Message from Gopher Robot:

Patch Set 1:

(1 comment)

Please don’t reply on this GitHub thread. Visit golang.org/cl/776300.
After addressing review feedback, remember to publish your drafts!

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gopherbot commented May 9, 2026

Message from Tiago Silva:

Patch Set 1:

(1 comment)

Please don’t reply on this GitHub thread. Visit golang.org/cl/776300.
After addressing review feedback, remember to publish your drafts!

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gopherbot commented May 9, 2026

This PR (HEAD: 616345e) has been imported to Gerrit for code review.

Please visit Gerrit at https://go-review.googlesource.com/c/go/+/776300.

Important tips:

  • Don't comment on this PR. All discussion takes place in Gerrit.
  • You need a Gmail or other Google account to log in to Gerrit.
  • To change your code in response to feedback:
    • Push a new commit to the branch used by your GitHub PR.
    • A new "patch set" will then appear in Gerrit.
    • Respond to each comment by marking as Done in Gerrit if implemented as suggested. You can alternatively write a reply.
    • Critical: you must click the blue Reply button near the top to publish your Gerrit responses.
    • Multiple commits in the PR will be squashed by GerritBot.
  • The title and description of the GitHub PR are used to construct the final commit message.
    • Edit these as needed via the GitHub web interface (not via Gerrit or git).
    • You should word wrap the PR description at ~76 characters unless you need longer lines (e.g., for tables or URLs).
  • See the Sending a change via GitHub and Reviews sections of the Contribution Guide as well as the FAQ for details.

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gopherbot commented May 9, 2026

Message from Gopher Robot:

Patch Set 1:

Congratulations on opening your first change. Thank you for your contribution!

Next steps:
A maintainer will review your change and provide feedback. See
https://go.dev/doc/contribute#review for more info and tips to get your
patch through code review.

Most changes in the Go project go through a few rounds of revision. This can be
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is our way of helping mentor contributors and ensuring that their contributions
have a lasting impact.

During May-July and Nov-Jan the Go project is in a code freeze, during which
little code gets reviewed or merged. If a reviewer responds with a comment like
R=go1.11 or adds a tag like "wait-release", it means that this CL will be
reviewed as part of the next development cycle. See https://go.dev/s/release
for more details.

Please don’t reply on this GitHub thread. Visit golang.org/cl/776300.
After addressing review feedback, remember to publish your drafts!

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