fix: advertise reset_stream_at on mvfst listeners by mondain · Pull Request #797 · openmoq/moqx

mondain · 2026-10-06T14:21:04Z

Current picoquic WebTransport clients refuse to send CONNECT when the mvfst listener omits the required reset_stream_at transport parameter. Enable advertisedReliableResetStreamSupport in the listener's transport settings so those clients can establish sessions.

Add real loopback handshake tests that verify the server's advertisement and acceptance of an HTTP/3 peer that does not advertise the extension.

Refs #752

Validation:

Default build succeeded; changed C++ files passed clang-format-19, and git diff --check passed.
Both new regression tests passed. The advertisement test failed against the original settings, as expected.
Both tests passed under ASan/UBSan; instrumentation covers moqx, with the pinned dependency stack uninstrumented.
The picoquic publisher reproduced the missing-parameter failure before the fix, then reached namespace/catalog publishing over WebTransport after the fix. Native QUIC also reached namespace/catalog publishing. No downstream media delivery was tested.
Full suite: 21 failures/timeouts out of 1124 tests, in UpstreamProviderTest, UpstreamSetupCancelledTest, and RelayUpstreamSubscribeRaceTest. Those fixtures bind ::1, while localhost resolves to 127.0.0.1 on this host. Both new tests passed in the full run.

Scope and remaining limitations:

This change is deliberately limited to moqx's missing advertisement; dependency revisions are unchanged.
The pinned mvfst still rejects incoming RESET_STREAM_AT frames, observed as a protocol error during publisher teardown. The pinned proxygen still uses ordinary resets for outgoing WebTransport streams. Full WebTransport reset compliance requires dependency follow-up; this PR does not claim to address those parts of WebTransport listener omits the reset_stream_at transport parameter required by draft-ietf-webtrans-http3 #752.

This change is

Summary by CodeRabbit

New Features
- QUIC connections now advertise support for reliable stream resets, helping clients identify this transport capability.
Tests
- Added connection checks for clients both with and without reliable-reset support.
- Verified that a reliable stream reset after a delivery checkpoint leaves the client connection open without connection errors.

coderabbitai · 2026-10-06T14:22:20Z

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test/MoqxRelayServerTest.cpp

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📝 Walkthrough

Walkthrough

The relay now advertises reliable reset-stream support in its QUIC transport settings. A new integration test target checks HTTP/3 connections with clients that enable or disable that support and checks a reliable stream reset.

Changes

Relay reliable reset-stream support

Layer / File(s)	Summary
Advertise reliable reset-stream support `src/MoqxRelayServer.cpp`	`buildTransportSettings` sets `advertisedReliableResetStreamSupport` to `true`.
Verify relay reset-stream behavior `test/MoqxRelayServerTest.cpp`, `test/CMakeLists.txt`	A loopback fixture connects QUIC clients to the relay. Tests check capability reporting, connection without client support, and client connection state after a reliable stream reset. CMake registers the test target.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Suggested reviewers: gmarzot

Merge Risk: 🔵 Low · up to c9b27

The change is mergeable with awareness that the new tests may fail on hosts without IPv6 loopback. No supported reliable-reset receive failure remains.

Pre-merge checks | 4 | 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.
Changelog Entry		The PR makes a user-visible change: mvfst listeners now advertise reliable reset_stream_at support, which allows compatible WebTransport clients to establish sessions. CONTRIBUTING.md requires each us…	Add this line under CHANGELOG.md -> [Unreleased] -> ## Fixed: - mvfst listeners advertise reset_stream_at for WebTransport clients. (`#797`)

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: advertising reset_stream_at in mvfst listeners.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Changelog Entry

Explanation

The PR makes a user-visible change: mvfst listeners now advertise reliable reset_stream_at support, which allows compatible WebTransport clients to establish sessions. CONTRIBUTING.md requires each user-visible change in [Unreleased]. The PR changes src/MoqxRelayServer.cpp and tests only; it does not modify CHANGELOG.md.

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Inline comments:
Review comments at @test/MoqxRelayServerTest.cpp:
- Around line 26-30: Update the listener address in the test fixture to use IPv4
loopback, 127.0.0.1, so server startup and client connections do not depend on
IPv6 loopback availability.

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gmarzot

@gmarzot reviewed 3 files and all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on afrind and mondain).

gmarzot · 2026-10-06T14:57:53Z

the pinned mvfst advertises and can send RESET_STREAM_AT, but rejects incoming ones. The server closes the whole connection with PROTOCOL_VIOLATION "Reliable resets not supported" (quic/server/state/ServerStateMachine.cpp). mvfst main still does this, so a moxygen sync won't fix it.

This matters mid-session, not only at teardown. Once both sides advertise, picoquic's WebTransport layer resets every stream it opened with RESET_STREAM_AT (picohttp/webtransport.c:182). So a picoquic WT publisher drops its relay connection the first time it resets a subgroup stream. That still beats not connecting at all, but before merging:

Please check that a Chrome WT client survives a mid-session reset/unsubscribe. Clients that work today may start sending RESET_STREAM_AT once we offer it.
Make the comment at src/MoqxRelayServer.cpp:136 say that mvfst rejects incoming RESET_STREAM_AT.
Add a test where the mvfst client calls updateReliableDeliveryCheckpoint + resetStreamReliably on a uni stream. It records the current connection close and will flip when mvfst is fixed.
Open a tracking issue for mvfst receive support. The stream state machine already handles reliable size; the frame-dispatch guard seems to be the main blocker.

Minor: AcceptsHttp3PeerWithoutReliableResetSupport passes with or without this change, and the setting is listener-wide, not WebTransport-only.

afrind

@afrind reviewed 3 files and all commit messages, and made 3 comments.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on mondain).

src/MoqxRelayServer.cpp line 136 at r1 (raw file):

  // Start with MoQServer's optimized defaults, then apply config overrides.
  quic::TransportSettings ts;
  // WebTransport over HTTP/3 draft-16 section 3.1 requires reset_stream_at.

Don't need a two line comment on this one setting prbably

test/MoqxRelayServerTest.cpp line 23 at r1 (raw file):

namespace {

class MoqxRelayServerTest : public ::testing::Test {

I wonder if we would prefer to use one of the shell/integration tests instead?

Check that a reliable RESET_STREAM_AT on an ignored H3 stream does not close the connection now that the listener advertises support. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

afrind

@afrind reviewed 2 files and all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on mondain).

fix: advertise reliable resets on mvfst listeners

7d9fba1

mondain requested a review from afrind October 6, 2026 14:22

coderabbitai Bot reviewed Oct 6, 2026

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Comment thread test/MoqxRelayServerTest.cpp

gmarzot approved these changes Oct 6, 2026

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afrind reviewed Oct 6, 2026

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Comment thread test/MoqxRelayServerTest.cpp

afrind and others added 2 commits October 9, 2026 16:59

test: reliable reset keeps the connection open

87b80db

Check that a reliable RESET_STREAM_AT on an ignored H3 stream does not close the connection now that the listener advertises support. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Merge branch 'main' into bug/752

c9b27af

afrind approved these changes Oct 10, 2026

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afrind merged commit c6607d3 into main Oct 10, 2026
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afrind deleted the bug/752 branch October 10, 2026 01:39

gmarzot mentioned this pull request Oct 10, 2026

changelog: cut 0.3.6 #809

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fix: advertise reset_stream_at on mvfst listeners - #797

fix: advertise reset_stream_at on mvfst listeners#797
afrind merged 3 commits into
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bug/752

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