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fix(http2): never write RST_STREAM ahead of the stream's still-queued HEADERS - #2008
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… HEADERS > [!NOTE] > This PR was generated by an AI coding agent (Jetski) on behalf of @mosuem. ### Summary `StreamHandler._terminateStream` (what `TransportStream.terminate()` ends up in) wrote the `RST_STREAM(CANCEL)` straight to the `FrameWriter`, bypassing `ConnectionMessageQueueOut`. If the stream's opening `HEADERS` were still sitting in that queue — because the socket was applying backpressure, or because the queue was head-of-line blocked behind flow-controlled `DATA` of another stream — the peer received `RST_STREAM` for a stream it had never seen, which is a connection error (RFC 9113 Section 6.4: *"RST_STREAM frames MUST NOT be sent for a stream in the "idle" state. If a RST_STREAM frame identifying an idle stream is received, the recipient MUST treat this as a connection error of type PROTOCOL_ERROR"*). A client cancelling a request shortly after starting it could thus take down the whole connection. ### Changes - **`lib/src/flowcontrol/connection_queues.dart`**: Add `ConnectionMessageQueueOut.cancelStreamMessages(streamId)`, which drops the stream's queued `DataMessage`s (they would be discarded by the peer anyway) and reports whether a `HeadersMessage` for the stream is still queued. - **`lib/src/streams/stream_handler.dart`**: In `_terminateStream`, enqueue a `ResetStreamMessage` behind the queued `HEADERS` when there are any; otherwise write the `RST_STREAM` directly as before. ### Test Verification (Fails Before $\rightarrow$ Passes After) Added `rst-stream-is-sent-after-queued-headers-of-the-stream` in `test/client_test.dart`. The test keeps the client's `FrameWriter` in its "would buffer" state (the server's `StreamIterator` pauses the frame stream after each frame, and that pause propagates synchronously into the client's `BufferedSink`), opens a stream and cancels it immediately, then checks the wire order. **Before fix:** ```text 00:00 +0 -1: client-tests client-errors rst-stream-is-sent-after-queued-headers-of-the-stream [E] Expected: <Instance of 'HeadersFrame'> with `streamId`: <3> Actual: <Instance of 'RstStreamFrame'> Which: is not an instance of 'HeadersFrame' ``` **After fix:** ```text 00:00 +1: All tests passed! ```
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…mosum/http2-4-control-frame-queue-and-rst-order # Conflicts: # pkgs/http2/CHANGELOG.md
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Revisions updated by 19 package dependencies found. Moving forward revisions for: http. Commit message: [deps] rev http Revisions updated by `dart tools/rev_sdk_deps.dart http`. http (https://github.com/dart-lang/http/compare/c76dfb3..c76dfb3): c76dfb3 Wed Oct 28 10:21:55 2026 -0700 Brian Quinlan fix(http2): accept larger headers (dart-lang/http#2041) 23495b0 Mon Oct 26 15:17:28 2026 -0700 Brian Quinlan chore(cronet_http): ready 1.10.1 (dart-lang/http#2039) 27591d4 Mon Oct 26 15:08:10 2026 -0700 Brian Quinlan fix(cronet): avoid cronet namespace duplication (dart-lang/http#2034) 9cdb8da Fri Oct 23 11:14:21 2026 -0700 Kevin Moore Tighten pull_request_label workflow permissions (dart-lang/http#2035) 3998b87 Fri Oct 23 07:31:29 2026 +0200 Moritz fix(http2): do not head-of-line block HEADERS, RST_STREAM and GOAWAY behind window-exhausted DATA (dart-lang/http#2013) be2b51f Fri Oct 23 07:31:28 2026 +0200 Moritz fix(http2): Http2Client applies response-body backpressure to the HTTP/2 stream and uses 4 MiB / 16 MiB receive windows (dart-lang/http#2029) 3b504cf Thu Oct 22 06:28:12 2026 +0200 Moritz fix(http2): never write RST_STREAM ahead of the stream's still-queued HEADERS (dart-lang/http#2008) a641fac Thu Oct 22 06:28:12 2026 +0200 Moritz fix(http2): preserve the complete response on RST_STREAM(NO_ERROR) (dart-lang/http#2012) 5d896c7 Thu Oct 22 06:28:11 2026 +0200 Moritz fix(http2): keep flow-controlled end-stream DATA alive until it is flushed (`#1998`) (dart-lang/http#2007) c834aa0 Thu Oct 22 06:28:11 2026 +0200 Moritz fix(http2): ignore PRIORITY and unknown frames on streams and reject non-zero stream control frames (dart-lang/http#2006) 2d35515 Thu Oct 22 06:15:59 2026 +0200 Moritz fix(http2): replenish connection receive window when stream closes with unconsumed data (dart-lang/http#2005) 1217181 Tue Oct 20 19:17:59 2026 -0400 Mouad Debbar [http_multi_server] Prepare to release 3.2.3 (dart-lang/http#2028). http (https://github.com/dart-lang/http/compare/a8a24a0..c76dfb3): c76dfb3 Wed Oct 28 10:21:55 2026 -0700 Brian Quinlan fix(http2): accept larger headers (dart-lang/http#2041) 23495b0 Mon Oct 26 15:17:28 2026 -0700 Brian Quinlan chore(cronet_http): ready 1.10.1 (dart-lang/http#2039) 27591d4 Mon Oct 26 15:08:10 2026 -0700 Brian Quinlan fix(cronet): avoid cronet namespace duplication (dart-lang/http#2034) 9cdb8da Fri Oct 23 11:14:21 2026 -0700 Kevin Moore Tighten pull_request_label workflow permissions (dart-lang/http#2035) 3998b87 Fri Oct 23 07:31:29 2026 +0200 Moritz fix(http2): do not head-of-line block HEADERS, RST_STREAM and GOAWAY behind window-exhausted DATA (dart-lang/http#2013) be2b51f Fri Oct 23 07:31:28 2026 +0200 Moritz fix(http2): Http2Client applies response-body backpressure to the HTTP/2 stream and uses 4 MiB / 16 MiB receive windows (dart-lang/http#2029) 3b504cf Thu Oct 22 06:28:12 2026 +0200 Moritz fix(http2): never write RST_STREAM ahead of the stream's still-queued HEADERS (dart-lang/http#2008) a641fac Thu Oct 22 06:28:12 2026 +0200 Moritz fix(http2): preserve the complete response on RST_STREAM(NO_ERROR) (dart-lang/http#2012) 5d896c7 Thu Oct 22 06:28:11 2026 +0200 Moritz fix(http2): keep flow-controlled end-stream DATA alive until it is flushed () (dart-lang/http#2007) c834aa0 Thu Oct 22 06:28:11 2026 +0200 Moritz fix(http2): ignore PRIORITY and unknown frames on streams and reject non-zero stream control frames (dart-lang/http#2006) 2d35515 Thu Oct 22 06:15:59 2026 +0200 Moritz fix(http2): replenish connection receive window when stream closes with unconsumed data (dart-lang/http#2005) 1217181 Tue Oct 20 19:17:59 2026 -0400 Mouad Debbar [http_multi_server] Prepare to release 3.2.3 (dart-lang/http#2028) Change-Id: I259130f06771f4b7ba61c7610847e6677b5c8ed5 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/570641 Reviewed-by: Nate Bosch <[email protected]> Commit-Queue: Brian Quinlan <[email protected]>
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Note
This PR was generated by an AI coding agent (Jetski) on behalf of @mosuem.
Summary
StreamHandler._terminateStream(whatTransportStream.terminate()ends up in) wrote theRST_STREAM(CANCEL)straight to theFrameWriter, bypassingConnectionMessageQueueOut. If the stream's openingHEADERSwere still sitting in that queue — because the socket was applying backpressure, or because the queue was head-of-line blocked behind flow-controlledDATAof another stream — the peer receivedRST_STREAMfor a stream it had never seen, which is a connection error (RFC 9113 Section 6.4: "RST_STREAM frames MUST NOT be sent for a stream in the "idle" state. If a RST_STREAM frame identifying an idle stream is received, the recipient MUST treat this as a connection error of type PROTOCOL_ERROR"). A client cancelling a request shortly after starting it could thus take down the whole connection.Changes
lib/src/flowcontrol/connection_queues.dart: AddConnectionMessageQueueOut.cancelStreamMessages(streamId), which drops the stream's queuedDataMessages (they would be discarded by the peer anyway) and reports whether aHeadersMessagefor the stream is still queued.lib/src/streams/stream_handler.dart: In_terminateStream, enqueue aResetStreamMessagebehind the queuedHEADERSwhen there are any; otherwise write theRST_STREAMdirectly as before.Test Verification (Fails Before$\rightarrow$ Passes After)
Added
rst-stream-is-sent-after-queued-headers-of-the-streamintest/client_test.dart. The test keeps the client'sFrameWriterin its "would buffer" state (the server'sStreamIteratorpauses the frame stream after each frame, and that pause propagates synchronously into the client'sBufferedSink), opens a stream and cancels it immediately, then checks the wire order.Before fix:
After fix: