ACKs are delivered in order panic when packets are reordered #1889
Description
I was trying to upgrade to quinn 0.11.2 and I have some tests where I implement AsyncUdpSocket with turmoil and my tests panic with ACKs are delivered in order (line 392 in mtud.rs) which originates from the BlackHoleDetector . After some experimentation I found that this happens because in our test with turmoil we have reordering of packets.
The issue can be reproduced if you locally add some reordering sudo tc qdisc add dev lo root netem delay 50ms 100ms and send some messages between a client and a server.
thread 'tokio-runtime-worker' panicked at quinn-proto/src/connection/mtud.rs:392:9:
ACKs are delivered in order
stack backtrace:
hello
0: rust_begin_unwind
at /rustc/9b00956e56009bab2aa15d7bff10916599e3d6d6/library/std/src/panicking.rs:645:5
1: core::panicking::panic_fmt
at /rustc/9b00956e56009bab2aa15d7bff10916599e3d6d6/library/core/src/panicking.rs:72:14
2: quinn_proto::connection::mtud::BlackHoleDetector::on_non_probe_acked
at ./quinn-proto/src/connection/mtud.rs:392:9
3: quinn_proto::connection::mtud::MtuDiscovery::on_acked
at ./quinn-proto/src/connection/mtud.rs:105:13
4: quinn_proto::connection::Connection::on_ack_received
at ./quinn-proto/src/connection/mod.rs:1387:35
5: quinn_proto::connection::Connection::process_payload
at ./quinn-proto/src/connection/mod.rs:2670:21
6: quinn_proto::connection::Connection::process_decrypted_packet
at ./quinn-proto/src/connection/mod.rs:2299:38
7: quinn_proto::connection::Connection::handle_packet
at ./quinn-proto/src/connection/mod.rs:2237:21
8: quinn_proto::connection::Connection::handle_decode
at ./quinn-proto/src/connection/mod.rs:2133:13
9: quinn_proto::connection::Connection::handle_event
at ./quinn-proto/src/connection/mod.rs:1069:17
10: quinn::connection::State::process_conn_events
at ./quinn/src/connection.rs:1026:21
11: <quinn::connection::ConnectionDriver as core::future::future::Future>::poll
at ./quinn/src/connection.rs:230:25
12: quinn::connection::Connecting::new::{{closure}}
at ./quinn/src/connection.rs:66:40
13: <tracing::instrument::Instrumented<T> as core::future::future::Future>::poll
This PR should fix the issue. It removes the ACK ordering requirement for non mtu probe acks.