[SSHD-207] ChannelForward TCP/IP sends EOF to server after closing channel

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.8.0
• Fix Version/s: 0.9.0
• Assignee: Guillaume Nodet
• Reporter: Andrew C
• Created: 30/Jan/13 20:20
• Updated: 19/Jul/13 05:50
• Resolved: 19/Jul/13 05:50

Description

This is the server's log:

[2013-01-28=15:05:04.742] [NioProcessor-2] DEBUG RelaySession - networkSessionClosed
[2013-01-28=15:05:04.742] [NioProcessor-2] DEBUG RelaySessionSshChannelSender - Send SSH_MSG_CHANNEL_CLOSE on channel 339
[2013-01-28=15:05:04.743] [NioProcessor-4] DEBUG SshSession - Received packet SSH_MSG_CHANNEL_CLOSE
[2013-01-28=15:05:04.743] [NioProcessor-4] DEBUG RelaySessionSshChannelSender - Received SSH_MSG_CHANNEL_CLOSE on channel 339
[2013-01-28=15:05:04.780] [NioProcessor-4] DEBUG SshSession - Received packet SSH_MSG_CHANNEL_EOF
[2013-01-28=15:05:04.780] [NioProcessor-4] WARN SshSession - Exception caught
org.apache.sshd.common.SshException: Received SSH_MSG_CHANNEL_EOF on unknown channel 339

this is the client log:

[2013-01-28=15:05:04.741] [NioProcessor-2] DEBUG RelaySessionSshChannelRecipient - Received SSH_MSG_CHANNEL_DATA on channel 339
[2013-01-28=15:05:04.741] [NioProcessor-682] DEBUG RelaySessionSshChannelRecipient - Send SSH_MSG_CHANNEL_DATA on channel 339
[2013-01-28=15:05:04.742] [NioProcessor-682] DEBUG RelaySessionSshChannelRecipient - Send SSH_MSG_CHANNEL_EOF on channel 339
[2013-01-28=15:05:04.743] [NioProcessor-2] DEBUG ClientSessionImpl - Received packet SSH_MSG_CHANNEL_CLOSE
[2013-01-28=15:05:04.743] [NioProcessor-2] DEBUG RelaySessionSshChannelRecipient - Received SSH_MSG_CHANNEL_CLOSE on channel 339
[2013-01-28=15:05:04.743] [NioProcessor-2] DEBUG RelaySessionSshChannelRecipient - Send SSH_MSG_CHANNEL_CLOSE on channel 339
[2013-01-28=15:05:04.743] [NioProcessor-2] DEBUG RelaySessionSshChannelRecipient - Closing channel 339 immediately

(RelaySessionSshChannelRecipient is just a hacked ChannelForwardTcpip client)

notice how order of close and eof get switched. I'm assuming it is because this:

@Override
public void sessionClosed(IoSession session) throws Exception {
if (!closing)

{ sendEof(); }

}

isn't locking other changes such as the incoming close.

A simple fix would be to just wrap it in a lock (Ditto for the same code in TcpipServerChannel), however I suspect a better fix would be to not bother with the EOF and just send a CLOSE - I think sending EOF is more applicable to pipes where it is possible to close just one side.

Issue Links

• is a clone of: SSHD-151 Direct TCP/IP Port Forward sends EOF to client after closing channel
• is part of: SSHD-238 Improve channel closing behaviors
• is related to: SSHD-206 Race between SSH_MSG_CHANNEL_DATA and SSH_MSG_CHANNEL_CLOSE in ChannelForwardedTcpip?