Fix TCP RST data loss when closing a connection with in-flight PING frames#112
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Fix TCP RST data loss when closing a connection with in-flight PING frames#112anluerz wants to merge 2 commits into
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Pull request overview
Fixes data loss caused by TCP RST during connection shutdown when an inbound packet (e.g., a SPDY PING) arrives at a socket that still has data in the kernel send buffer. Before closing the underlying connection, shutdown now half-closes the write side and drains any inbound bytes for up to 10 seconds so the kernel emits FIN instead of RST and the peer can finish receiving in-flight data. Also fixes a minor race in Ping by reading s.pingId under pingLock.
Changes:
- In
Connection.shutdown, after all streams close, performCloseWrite+ boundedio.Copy(io.Discard, s.conn)drain befores.conn.Close(). - Move
pid := s.pingIdinside thepingLockcritical section inConnection.Ping. - Add
TestReceiveBufferIsDrainedto reproduce the truncated-transfer scenario with backpressure and concurrent pings.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.
| File | Description |
|---|---|
| connection.go | Drain inbound bytes during graceful shutdown; tighten locking around pingId read in Ping. |
| spdy_test.go | New regression test that fills the send buffer, closes the server side, sends pings, and verifies all bytes are received. |
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Server closes connection while client sends periodic PING frames. A PING arriving after conn.Close() triggers RST, causing the kernel to discard the server's TCP send buffer. Signed-off-by: Andreas Erz <andreas.erz@sap.com>
Half-close with CloseWrite() and wait for Serve() to exit before calling conn.Close(), so late peer packets don't trigger RST. Also fix a pre-existing data race in Ping() where s.pingId was read outside pingLock. Signed-off-by: Andreas Erz <andreas.erz@sap.com>
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Fixes #111