fix(quic): close inbound connection when handler rejects it#499
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lucassaldanha merged 2 commits intoJun 24, 2026
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The inbound QUIC server path invokes the application connection handler synchronously inside channelActive. When the handler rejects the connection by throwing (e.g. PeerAlreadyConnectedException for a duplicate/simultaneous peer), the handshake-waiter handler has already removed itself, so the exception reaches the Netty pipeline tail and logs a noisy 'exceptionCaught reached tail of pipeline' warning while leaking the rejected QuicChannel until idle timeout. Catch the exception in routeInboundHandshake and close the channel, mirroring the dial paths which already close on handler failure.
Narrow the inbound rejection guard from catch(Throwable) to catch(Exception) so fatal Errors (OutOfMemoryError, LinkageError, ...) propagate instead of being downgraded to a routine connection close. The library cannot distinguish a deliberate rejection from an application bug, so logging stays at debug to avoid reintroducing noise.
lucassaldanha
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Jun 24, 2026
The inbound QUIC server path invokes the application connection handler synchronously inside channelActive. When the handler rejects the connection by throwing (e.g. PeerAlreadyConnectedException for a duplicate/simultaneous peer), the handshake-waiter handler has already removed itself, so the exception reaches the Netty pipeline tail and logs a noisy 'exceptionCaught reached tail of pipeline' warning while leaking the rejected QuicChannel until idle timeout. Catch the exception in routeInboundHandshake and close the channel, mirroring the dial paths which already close on handler failure. Narrow the guard to catch(Exception) rather than Throwable so fatal Errors (OutOfMemoryError, LinkageError, ...) propagate instead of being downgraded to a routine connection close; logging stays at debug.
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Problem
Teku nodes log a flood of noisy warnings on the QUIC inbound path:
Problem/Fix
When the handler rejects the connection by throwing
PeerAlreadyConnectedExceptionthis is ok for a duplicate connection to an already-connected peer. We just need to handle it better.This is already handled in a similar way for QUIC dialing (outbound). And in the TCP path as well.