Major Description
Wanted to open a local port forwarding to an SSH server and afterwards connect to MQTT server over the SSh tunnel. During the MQTT connection attempt I encountered a SocketTimeoutException in the logs (StackTrace below).
What I could see in the logs is that the server is sending an initial window size of 0 and afterwards the waitForCondition method is throwing the SocketTimeoutException .
After analyzing the logs I maybe have an idea what is going on here. My assumption is that there is some deadlock in case the initial window size is 0 and the SSH_MSG_CHANNEL_WINDOW_ADJUST isn't handled properly.
I have attached the whole log file. Lines of interest are from 169 to 229.
Tested with 2.7.0 and 2.8.0.
WARN org.apache.sshd.common.forward.DefaultForwarder - exceptionCaught(Nio2Session[local=/127.0.0.1:44259, remote=/127.0.0.1:60188]) SocketTimeoutException: waitForCondition(Window[client/remote](TcpipClientChannel[id=0, recipient=0]-ClientSessionImpl[Admin@/x.xxx.xx.x:xxxx])) timeout exceeded: PT30S java.net.SocketTimeoutException: waitForCondition(Window[client/remote](TcpipClientChannel[id=0, recipient=0]-ClientSessionImpl[Admin@/x.xxx.xx.x:xxxx])) timeout exceeded: PT30S at org.apache.sshd.common.channel.Window.waitForCondition(Window.java:332) at org.apache.sshd.common.channel.Window.waitForSpace(Window.java:286) at org.apache.sshd.common.channel.ChannelOutputStream.write(ChannelOutputStream.java:154) at org.apache.sshd.client.channel.ClientChannelPendingMessagesQueue.writeMessage(ClientChannelPendingMessagesQueue.java:174) at org.apache.sshd.client.channel.ClientChannelPendingMessagesQueue.flushPendingQueue(ClientChannelPendingMessagesQueue.java:221) at org.apache.sshd.client.channel.ClientChannelPendingMessagesQueue.operationComplete(ClientChannelPendingMessagesQueue.java:206) at org.apache.sshd.client.channel.ClientChannelPendingMessagesQueue.operationComplete(ClientChannelPendingMessagesQueue.java:51) at org.apache.sshd.common.future.AbstractSshFuture.notifyListener(AbstractSshFuture.java:159) at org.apache.sshd.common.future.DefaultSshFuture.notifyListeners(DefaultSshFuture.java:215) at org.apache.sshd.common.future.DefaultSshFuture.setValue(DefaultSshFuture.java:112) at org.apache.sshd.client.future.DefaultOpenFuture.setOpened(DefaultOpenFuture.java:68) at org.apache.sshd.client.channel.AbstractClientChannel.handleOpenSuccess(AbstractClientChannel.java:360) at org.apache.sshd.common.session.helpers.AbstractConnectionService.channelOpenConfirmation(AbstractConnectionService.java:545) at org.apache.sshd.common.session.helpers.AbstractConnectionService.process(AbstractConnectionService.java:456) at org.apache.sshd.common.session.helpers.AbstractSession.doHandleMessage(AbstractSession.java:503) at org.apache.sshd.common.session.helpers.AbstractSession.handleMessage(AbstractSession.java:429) at org.apache.sshd.common.session.helpers.AbstractSession.decode(AbstractSession.java:1466) at org.apache.sshd.common.session.helpers.AbstractSession.messageReceived(AbstractSession.java:389) at org.apache.sshd.common.session.helpers.AbstractSessionIoHandler.messageReceived(AbstractSessionIoHandler.java:64) at org.apache.sshd.common.io.nio2.Nio2Session.handleReadCycleCompletion(Nio2Session.java:359) at org.apache.sshd.common.io.nio2.Nio2Session$1.onCompleted(Nio2Session.java:336) at org.apache.sshd.common.io.nio2.Nio2Session$1.onCompleted(Nio2Session.java:333) at org.apache.sshd.common.io.nio2.Nio2CompletionHandler.lambda$completed$0(Nio2CompletionHandler.java:38) at java.base/java.security.AccessController.doPrivileged(AccessController.java:318) at org.apache.sshd.common.io.nio2.Nio2CompletionHandler.completed(Nio2CompletionHandler.java:37) at java.base/sun.nio.ch.Invoker.invokeUnchecked(Invoker.java:129) at java.base/sun.nio.ch.Invoker$2.run(Invoker.java:221) at java.base/sun.nio.ch.AsynchronousChannelGroupImpl$1.run(AsynchronousChannelGroupImpl.java:113) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) at java.base/java.lang.Thread.run(Thread.java:833)
