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On STREAM emission, quic-conn notifies MUX through a callback named qcc_streams_sent_done(). This also happens on retransmission : in this case offset are examined and notification is ignored if already seen. However, this behavior has slightly changed since e53b489826ba9760a527b461095402ca05d2b6be BUG/MEDIUM: mux-quic: fix server chunked encoding response Indeed, if offset diff is NULL, frame is now not ignored. This is to support FIN notification with a final empty STREAM frame. A side-effect of this is that if the last stream frame is retransmitted, it won't be ignored in qcc_streams_sent_done(). In most cases, this side-effect is harmless as qcs instance will soon be freed after being closed. But if qcs is still alive, this will cause a BUG_ON crash as it is considered as locally closed. This bug depends on delay condition and seems to be extremely rare. But it might be the reason for a crash seen on interop with s2n client on http3 testcase : FATAL: bug condition "qcs->st == QC_SS_CLO" matched at src/mux_quic.c:372 call trace(16): | 0x558228912b0d [b8 01 00 00 00 c6 00 00]: main-0x1c7878 | 0x558228917a70 [48 8b 55 d8 48 8b 45 e0]: qcc_streams_sent_done+0xcf/0x355 | 0x558228906ff1 [e9 29 05 00 00 48 8b 05]: main-0x1d3394 | 0x558228907cd9 [48 83 c4 10 85 c0 0f 85]: main-0x1d26ac | 0x5582289089c1 [48 83 c4 50 85 c0 75 12]: main-0x1d19c4 | 0x5582288f8d2a [48 83 c4 40 48 89 45 a0]: main-0x1e165b | 0x5582288fc4cc [89 45 b4 83 7d b4 ff 74]: qc_send_app_pkts+0xc6/0x1f0 | 0x5582288fd311 [85 c0 74 12 eb 01 90 48]: main-0x1dd074 | 0x558228b2e4c1 [48 c7 c0 d0 60 ff ff 64]: run_tasks_from_lists+0x4e6/0x98e | 0x558228b2f13f [8b 55 80 29 c2 89 d0 89]: process_runnable_tasks+0x7d6/0x84c | 0x558228ad9aa9 [8b 05 75 16 4b 00 83 f8]: run_poll_loop+0x80/0x48c | 0x558228ada12f [48 8b 05 aa c5 20 00 48]: main-0x256 | 0x7ff01ed2e609 [64 48 89 04 25 30 06 00]: libpthread:+0x8609 | 0x7ff01e8ca163 [48 89 c7 b8 3c 00 00 00]: libc:clone+0x43/0x5e To reproduce it locally, code was artificially patched to produce retransmission and avoid qcs liberation. In order to fix this and avoid future class of similar problem, the best way is to not call qcc_streams_sent_done() to notify MUX for retranmission. To implement this, we test if any of QUIC_FL_CONN_RETRANS_OLD_DATA or the new flag QUIC_FL_CONN_RETRANS_LOST_DATA is set. A new wrapper qc_send_app_retransmit() has been added to set the new flag as a complement to already existing qc_send_app_probing(). This must be backported up to 2.6.
The HAProxy documentation has been split into a number of different files for ease of use. Please refer to the following files depending on what you're looking for : - INSTALL for instructions on how to build and install HAProxy - BRANCHES to understand the project's life cycle and what version to use - LICENSE for the project's license - CONTRIBUTING for the process to follow to submit contributions The more detailed documentation is located into the doc/ directory : - doc/intro.txt for a quick introduction on HAProxy - doc/configuration.txt for the configuration's reference manual - doc/lua.txt for the Lua's reference manual - doc/SPOE.txt for how to use the SPOE engine - doc/network-namespaces.txt for how to use network namespaces under Linux - doc/management.txt for the management guide - doc/regression-testing.txt for how to use the regression testing suite - doc/peers.txt for the peers protocol reference - doc/coding-style.txt for how to adopt HAProxy's coding style - doc/internals for developer-specific documentation (not all up to date)