TLSv1.3 fails / java.nio.channels.ClosedChannelException: null

[schnapster]

Currently, on most JVM distributions, TLSv1.3 negotiation with Cloudflare is broken.
As soon as the audio websocket tries to connect to discord voice servers, the following or similar exception is thrown:

20:26:37.147 [XNIO-1 I/O-1] DEBUG io.undertow.request - UT005013: An IOException occurred
java.nio.channels.ClosedChannelException: null
	at io.undertow.protocols.ssl.SslConduit.doWrap(SslConduit.java:876)
	at io.undertow.protocols.ssl.SslConduit.doHandshake(SslConduit.java:649)
	at io.undertow.protocols.ssl.SslConduit.access$900(SslConduit.java:63)
	at io.undertow.protocols.ssl.SslConduit$SslReadReadyHandler.readReady(SslConduit.java:1137)
	at org.xnio.nio.NioSocketConduit.handleReady(NioSocketConduit.java:88)
	at org.xnio.nio.WorkerThread.run(WorkerThread.java:561)
Exception in thread "main" java.lang.IllegalStateException: Failed to connect to wss://brazil0-test-proxy.discord.gg/
	at space.npstr.magma.impl.connections.hax.ClosingUndertowWebSocketClient$1.handleFailed(ClosingUndertowWebSocketClient.java:79)
	at org.xnio.IoFuture$HandlingNotifier.notify(IoFuture.java:215)
	at org.xnio.AbstractIoFuture$1.run(AbstractIoFuture.java:211)
	at org.xnio.IoUtils$2.execute(IoUtils.java:70)
	at org.xnio.AbstractIoFuture.runNotifier(AbstractIoFuture.java:354)
	at org.xnio.AbstractIoFuture.runAllNotifiers(AbstractIoFuture.java:233)
	at org.xnio.AbstractIoFuture.setException(AbstractIoFuture.java:251)
	at org.xnio.FutureResult.setException(FutureResult.java:89)
	at io.undertow.websockets.client.WebSocketClient$ConnectionBuilder$2.notify(WebSocketClient.java:342)
	at org.xnio.AbstractIoFuture$1.run(AbstractIoFuture.java:211)
	at org.xnio.IoUtils$2.execute(IoUtils.java:70)
	at org.xnio.AbstractIoFuture.runNotifier(AbstractIoFuture.java:354)
	at org.xnio.AbstractIoFuture.runAllNotifiers(AbstractIoFuture.java:233)
	at org.xnio.AbstractIoFuture.setException(AbstractIoFuture.java:251)
	at org.xnio.FutureResult.setException(FutureResult.java:89)
	at org.xnio.http.HttpUpgrade$HttpUpgradeState$StringWriteListener.handleEvent(HttpUpgrade.java:391)
	at org.xnio.http.HttpUpgrade$HttpUpgradeState$StringWriteListener.handleEvent(HttpUpgrade.java:372)
	at org.xnio.ChannelListeners.invokeChannelListener(ChannelListeners.java:92)
	at org.xnio.conduits.WriteReadyHandler$ChannelListenerHandler.writeReady(WriteReadyHandler.java:65)
	at io.undertow.protocols.ssl.SslConduit$SslWriteReadyHandler.writeReady(SslConduit.java:1273)
	at io.undertow.protocols.ssl.SslConduit$3.run(SslConduit.java:275)
	at org.xnio.nio.WorkerThread.safeRun(WorkerThread.java:582)
	at org.xnio.nio.WorkerThread.run(WorkerThread.java:466)
	Suppressed: java.lang.Exception: #block terminated with an error
		at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:93)
		at reactor.core.publisher.Mono.block(Mono.java:1494)
		at space.npstr.magma.Application.main(Application.java:59)
Caused by: java.nio.channels.ClosedChannelException
	at io.undertow.protocols.ssl.SslConduit.write(SslConduit.java:369)
	at org.xnio.conduits.ConduitStreamSinkChannel.write(ConduitStreamSinkChannel.java:150)
	at org.xnio.http.HttpUpgrade$HttpUpgradeState$StringWriteListener.handleEvent(HttpUpgrade.java:385)
	... 7 more

Until the root cause is found and fixed, a possible workaround is to specify TLSv1.2 in the SSL options as the preferred protocol. This is available since Magma 0.12.6

OptionMap sslOptions = OptionMap.create(
    Options.SSL_PROTOCOL, "TLSv1.2"
);
MagmaApi magmaApi = MagmaFactory.of(__ -> audioSendFactory, xnioOptions, sslOptions);