Bun.serve(http3): keep accepting the client's unidirectional streams after GOAWAY - #42690
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A connection that sent GOAWAY answered every new peer stream with STOP_SENDING(H3_REQUEST_REJECTED), unidirectional ones included. GOAWAY only rejects requests (RFC 9114 section 5.2). An lsquic client opens its QPACK encoder stream when the server's SETTINGS arrive. On a connection whose first request handler calls server.stop(), that is after the GOAWAY. Since lsquic 4.9.2 the client treats STOP_SENDING on a critical stream as H3_CLOSED_CRITICAL_STREAM and closes the connection, so the request the graceful stop was draining failed with HTTP3StreamReset. Reject only bidirectional streams while going away.
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Updated 2:01 AM PT - Sep 14th, 2026
✅ @robobun, your commit cda0806804d8eab49b2cfa3422bd59d2b7105f66 passed in 🧪 To try this PR locally: bunx bun-pr 42690That installs a local version of the PR into your bun-42690 --bun |
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Status
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WalkthroughThe lsquic GOAWAY patch now rejects only incoming bidirectional request streams. Unidirectional control and QPACK streams remain accepted. An HTTP/3 shutdown test validates this behavior and request completion. ChangesHTTP/3 graceful shutdown
Suggested reviewers: Priority: ⬇️ Low Merge Risk: 🔵 Low · up to Graceful shutdown could regress to accepting new HTTP/3 requests without this test detecting it. Add the post-GOAWAY rejection assertion before merging. 🚥 Pre-merge checks | ✅ 4✅ Passed checks (4 passed)
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In `@test/js/bun/http/serve-http3.test.ts`:
- Around line 1200-1242: Extend the test around the existing goaway promise and
request stream so it waits for GOAWAY, then opens a second bidirectional request
stream and verifies it receives STOP_SENDING with H3_REQUEST_REJECTED. Keep the
original assertion that the first pre-GOAWAY request still completes and accepts
the client’s QPACK encoder stream.
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patches/lsquic/goaway-accept-uni-streams.patchscripts/build/deps/lsquic.tstest/js/bun/http/serve-http3.test.ts
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I reviewed this PR and didn't find any bugs. Because it patches lsquic's post-GOAWAY stream-acceptance logic — protocol-level behavior in a vendored C library — a human sign-off on the RFC 9114 §5.2 reading and the "only one of three IFC_GOING_AWAY sites needs the guard" argument would still be worthwhile.
What was reviewed
- Patch semantics:
SD_BIDI == ((stream_id >> SD_SHIFT) & 1)correctly narrows the STOP_SENDING to bidi streams; uni streams remain bounded by the earlier MAX_STREAMS check, so this can't admit unbounded new streams. - Registration in
scripts/build/deps/lsquic.tsmatches the other 10 lsquic patches; none carry aworkarounds.tsentry, so its absence here is consistent. - Test: awaits
ongoaway(no sleep),port: 0,await usingcleanup, exact-string assertion, and the failure path (closed: …) feeds into the assertedoutcomeso a regression surfaces the reason instead of hanging.
Extended reasoning...
Overview
The PR adds one vendor patch to lsquic (patches/lsquic/goaway-accept-uni-streams.patch) that adds a single && is-bidirectional condition to the post-GOAWAY new-stream rejection in process_stream_frame, registers it in scripts/build/deps/lsquic.ts alongside ten existing lsquic patches of the same shape, and adds one regression test to test/js/bun/http/serve-http3.test.ts that drives a same-thread node:quic client against Bun.serve({ http3: true }) to make the ordering deterministic.
Security risks
The change only narrows when the server sends STOP_SENDING during graceful shutdown; it does not remove any bound. Peer-initiated unidirectional streams remain limited by the MAX_STREAMS credit that is checked before this branch, and IFC_GOING_AWAY is only set in HTTP mode, so raw-QUIC callers are unaffected. I don't see a way for this to admit unbounded resources or bypass a security check — it stops the server from provoking the client into tearing down the connection it is trying to drain. The bidi test uses lsquic's own SD_BIDI/SD_SHIFT constants, so it matches how the file already classifies stream direction.
Level of scrutiny
Higher than a typical one-liner because it edits protocol behavior in a vendored C networking library, and the correctness argument rests on an RFC reading (9114 §5.2 / §6.2.1) plus a claim that the two sibling IFC_GOING_AWAY checks in process_stop_sending_frame / process_max_stream_data_frame already filter to bidi via an earlier conn_is_receive_only_stream guard. The PR description argues both convincingly, but a maintainer should confirm rather than take an automated review's word for it on a QUIC state-machine change.
Other factors
No CODEOWNERS entry covers patches/, scripts/build/deps/, or this test file. The patch and its lsquic.ts comment follow the exact style of the surrounding entries, and none of the existing lsquic patches register a workarounds.ts entry, so its absence here is consistent with local convention. The new test follows the repo's rules: added to the existing serve-http3.test.ts, port: 0, no sleep/setTimeout (it awaits ongoaway via Promise.withResolvers and races it against the response outcome), resources released via await using before the assertion, and the failure path reports the client-close reason so a regression fails with a diagnostic string rather than a timeout. Bug-hunt exit reason was dry_streak with no findings and no ruled-out candidates.
…cted The handler makes the client send a second request before the client has read the GOAWAY. The server reads it after the GOAWAY left, so the handler must not run for it. Without the going-away check in process_stream_frame the handler runs twice.
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Review follow-up for cda0806:
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2 participants
Problem
Bun.serve({ http3: true }): a gracefulserver.stop()inside the handler of the first request on a connection kills that request.fetchrejects withHTTP3StreamReset. The client log saysreceived STOP_SENDING on critical stream 10. Release main: 21 of 30 runs fail.STOP_SENDING(H3_REQUEST_REJECTED), unidirectional ones too (process_stream_frame,lsquic_full_conn_ietf.c:5873). An lsquic client opens its QPACK encoder stream when the server's SETTINGS arrive. On a new connection that is after the GOAWAY.H3_CLOSED_CRITICAL_STREAMon that frame. 4.6.2 only reset the stream.Fix
patches/lsquic/goaway-accept-uni-streams.patch: while going away, reject only bidirectional streams.test/js/bun/http/serve-http3.test.ts. Release main without the patch fails it 12 of 12. With the patch it passes 25 of 25. It also pins that a request after the GOAWAY is still rejected. Also ranfetch-http3-*,serve-protocols,test/js/node/quic.scripts/build/deps/lsquic.ts. The fix is not undersrc/.Background
server.stop()sends it throughlsquic_engine_cooldown.Notes
Where this comes from. Found while verifying #42619 on a release build of main. The script: the handler of the first request calls
server.stop(), awaits 30 ms, then answers. #42619 is not the cause. Its own graceful tests answer in the same tick asstop(), so the response is complete before the client closes the connection.Repro script. Needs
openssl req -x509 -newkey rsa:2048 -nodes -keyout key.pem -out cert.pem -days 2 -subj /CN=localhost. Runbun t.mjs h3 cold /, thencold /stream,warm /,http1.1 cold /.Sequence, from
BUN_DEBUG_lsquic=1on a debug build.server.stop(). Afterprocess_connsreturns, the server sends its first 1-RTT flight (SETTINGS) and then the GOAWAY.qenc-hdl: initialized outgoing encoder stream).going away: reject new incoming stream 10, thengenerated STOP_SENDING frame; stream ID: 10; error code: 267.Abort connection: received STOP_SENDING on critical stream 10, then CONNECTION_CLOSE. Every request on the connection dies.A warm connection already has stream 10, so it is not affected. A
stop()from a timer runs after the client's encoder stream arrived. When the Finished and the request arrive in two batches the client can win the race, which is why the failure rate is below 100%.Why only one of the three
IFC_GOING_AWAYchecks changes.process_stop_sending_frameandprocess_max_stream_data_framehave the same check. Both reject receive-only streams first (conn_is_receive_only_stream), so a peer-initiated stream that reaches the check is always bidirectional.IFC_GOING_AWAYis only set in HTTP mode (ietf_full_conn_ci_going_awayreturns early otherwise). The peer's unidirectional streams stay bounded by the MAX_STREAMS credit, which is checked before.The silently truncated
200 "part1"is a second bug, on the client. The fetch HTTP/3 client treats every stream close after the response headers as a clean end of body (h3_client/callbacks.rs,on_stream_close). #40598 already fixes that. With this patch the connection is no longer closed, so the/streamcase of the script completes.Numbers (the script above, client and server in one process).
//streamHTTP3StreamReset200 "part1"200 "late"200 "part1part2"HTTP3StreamReset200 "part1"Warm and
http1.1cells pass on every build.The test. A
node:quicclient runs on the same thread as the server, which makes the order exact. It creates the request stream before the handshake completes, so the HEADERS leave with the Finished and the handler runs in the promotion tick. It ends the request body whenongoawayfires. The handler awaits the body, so it answers only after the server has read stream 10. Without the patch the test getsclosed: QUIC transport error 1: received STOP_SENDING on critical stream 10(12 of 12 on a release build of main, 4 of 4 on a debug build, 11 of 11 on release 1.4.3-canary.1+09bb54630 for the first version of the test). With the patch it gets200 late:body(25 of 25 on a release build). Afetch-based test of the same thing depends on thread timing, so it is not included.The test also pins the other side of the changed condition. Right after
server.stop()the handler makes the client send a second request. The client has not read the GOAWAY yet (after it has,node:quicrefuses to open a stream), and the server reads the request after the GOAWAY left. The test asserts that the handler runs once. With theIFC_GOING_AWAYcheck inprocess_stream_framedisabled the handler runs twice and the test fails withhandled: 2.node:quicends a stream above the GOAWAY id without an error, so theSTOP_SENDINGcode is not visible in JS. The lsquic debug log shows it:going away: reject new incoming stream 4, thengenerated STOP_SENDING frame; stream ID: 4; error code: 267.Suites run on the debug ASAN build with the patch:
serve-http3(63 pass),fetch-http3-client(56),fetch-http3-adversarial(27),fetch-http3-cold-post(2),fetch-http3-syscall-fault(3),serve-protocols(20),test/js/node/quic(17),test/js/node/test/parallel/test-quic-h3-*(24 of 25;test-quic-h3-stream-idle-timeout.mjsimportsnode:stream/iter, which does not exist, with or without this change).[policy-decision:dep] gate passed · iteration 0 · 3 files touched
passes on PR (with fix)
diff hotspot
gate history · 2 passed · 0 rejected · iteration 0
evidence per changed file