epoll/kqueue transport bind exception detection does not work on linux with LANGUAGE != en

When trying to start a server with a port that is already bind on a epoll/kqueue transport based linux system with LANGUAGE not set to en a io.netty.channel.unix.Errors$NativeIoException instead of a ChannelBindException is thrown.

This leads to failed test cases when trying to build reactor-netty

UdpServerTests > portBindingException() FAILED
    reactor.core.Exceptions$ReactiveException: io.netty.channel.unix.Errors$NativeIoException: bind(..) failed: Die Adresse wird bereits verwendet
        at reactor.core.Exceptions.propagate(Exceptions.java:392)
        at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:137)
        at reactor.core.publisher.Mono.block(Mono.java:1727)
        at reactor.netty.udp.UdpServer.bindNow(UdpServer.java:120)
        at reactor.netty.udp.UdpServerTests.portBindingException(UdpServerTests.java:266)

        Caused by:
        io.netty.channel.unix.Errors$NativeIoException: bind(..) failed: Die Adresse wird bereits verwendet

264 tests completed, 4 failed, 3 skipped

Expected Behavior

ChannelBindException for e.g. test case UdpServerTests.portBindingException

Actual Behavior

io.netty.channel.unix.Errors$NativeIoException is handled by reactor-netty and wrapped in ChannelBindException

Steps to Reproduce

Execute UdpServerTests.portBindingException on an epoll/kqueue based linux

Possible Solution

Root problem seems to be the current solution which tries to detect and wrap such exception based on the message string provided by the underlying OS.

The string check Address already in use will fail on linux environments with a different language. When setting the language to german the message provided by the OS is Die Adresse wird bereits verwendet

Maybe the check can be based on the cannonical name of the class instead

/**
* Check if {@code t} is a {@link BindException}
*
* @param t {@code Throwable} to check
* @return true if {@code t} is a {@link BindException}
*/
private boolean isBindException(Throwable t) {
	if (t instanceof BindException) {
		return true;
	}
	// With epoll/kqueue transport it is
	// io.netty.channel.unix.Errors$NativeIoException: bind(..) failed: Address already in use
	else if (t instanceof IOException && t.getClass().getCanonicalName().equals("io.netty.channel.unix.Errors.NativeIoException")) {
		return true;
	}
	return false;
}

@Override
public void onError(Throwable t) {
	if (bindAddress != null && isBindException(t)) {
		sink.error(ChannelBindException.fail(bindAddress.get(), null));
	}
	else {
		sink.error(t);
	}
}

Your Environment

Reactor version(s) used: reactor-netty 1.0.7 JVM version : OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.7+10, mixed mode) OS and version: Linux 5.12.10-arch1-1 #1 SMP PREEMPT Thu, 10 Jun 2021 16:34:50 +0000 x86_64 GNU/Linux

[roggenbrot]

You’re right. I will submit a push request

[violetagg]

It should be this one

https://github.com/netty/netty/blob/0d5774a82b470833c5f8a84fa4708142a4801f52/transport-native-unix-common/src/main/java/io/netty/channel/unix/Errors.java#L84

so most probably it will be OK wdyt?