[
https://issues.apache.org/jira/browse/SSHD-848?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16641940#comment-16641940
]
Roberto Deandrea commented on SSHD-848:
---------------------------------------
Our proposed solution in StaticIOHandler.sessionCreated() caused a deadlock in
SSH client. We found a better solution for the issue changing code in
StaticIOHandler.sessionClosed() in defaultForwardingFilter.java.
We changed the code as the following:
@Override
public void sessionClosed(IoSession session) throws Exception {
TcpipClientChannel channel = (TcpipClientChannel)
session.removeAttribute(TcpipClientChannel.class);
Throwable cause = (Throwable)
session.removeAttribute(TcpipForwardingExceptionMarker.class);
if (channel != null) {
if (debugEnabled) {
log.debug("sessionClosed({}) closing channel={} after {}
messages - cause={}",
session, channel, messagesCounter, (cause == null)
? null : cause.getClass().getSimpleName());
}
if (cause != null) {
channel.close(true);
} else {
OpenFuture openFuture = channel.getOpenFuture();
// channel.getOpenFuture().await();
if (!openFuture.isDone()) {
openFuture.addListener(f -> {
// If exception signaled then close channel immediately
channel.close(false);
});
}
else {
channel.close(false);
}
}
}
}
What do you think about it?
> Possible bug opening local port forwarding channel
> --------------------------------------------------
>
> Key: SSHD-848
> URL: https://issues.apache.org/jira/browse/SSHD-848
> Project: MINA SSHD
> Issue Type: Bug
> Affects Versions: 2.0.1
> Reporter: Roberto Deandrea
> Priority: Major
> Attachments: testlpf.ko, testlpf.ok
>
>
> Hi , We found a possible bug opening a local port forwarding channel.
> Scenario : The SSH client and server are based on Apache SSHD 2.0.1. There is
> a FTP client sending a file through a local port forwarding channel to a
> target server.
> The problem manifests when the SSH server is busy and returns the
> SSH_MSG_CHANNEL_OPEN_CONFIRMATION with a some delay and the client is very
> fast to send only a few bytes on a local port forwarding channel.
> The outcome is the FTP client is NOT able to send bytes through the channel
> to the target server.
> Into SSH client traces we see :
> org.apache.sshd.common.channel.WindowClosedException: Already closed:
> Window[client/remote](TcpipClientChannel[id=4,
> recipient=4]-ClientSessionImpl[roberto@/192.168.50.61:10022])
>
> According to us there is a chance that if we don't AWAIT the local port
> forward channel is TOTALLY opened, when the client is very fast to send
> bytes... it closes its connection, ao the channel that is already closing
> prevents bytes to flow through the channel to the target server.
>
> We guess there is a code bug in *DefaultForwardingFilter.sessionCreated()*
> method.
> We add the following line at the end of the method and the problem seems
> definitely fixed.
> *channel.getOpenFuture().await();*
>
> Please, can you troubleshoot this issue and comment about our potential code
> fix ?
> Thanks in advance.
>
> I attached the files:
> testslpf.ko SSH client traces with original code and a failed attempt
> testslpf.ok SSH client traces with our code changes and a successful attempt
>
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
