Andrew C created SSHD-206:
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Summary: Race between SSH_MSG_CHANNEL_DATA and
SSH_MSG_CHANNEL_CLOSE in ChannelForwardedTcpip?
Key: SSHD-206
URL: https://issues.apache.org/jira/browse/SSHD-206
Project: MINA SSHD
Issue Type: Bug
Affects Versions: 0.8.0
Reporter: Andrew C
I've noticed what I believe is a race between ChannelForwardTcpip receiving
SSH_MSG_CHANNEL_CLOSE from the remote end and it trying to send data to the
remote end - it ends up sending data after it closed the channel :-(
The sequence is roughly:
- remote forwards tcp channel to local
- remote and local chatter
- remote gets a close and sends SSH_MSG_CHANNEL_CLOSE to local
- local responds accordingly
meanwhile, there's data intended for the remote end still sitting in a local
queue somewhere and local proceeds to send it across the now dead channel
- remote responds to the protocol violation with extreme prejudice killing the
entire ssh session ;-)
This is the local log (s/RelaySessionSshChannelRecipient/ChannelForwardTcpip/,
they are essentially the same)
[09:42:32.451] [NioProcessor-2] DEBUG
org.apache.sshd.client.session.ClientSessionImpl - Received packet
SSH_MSG_CHANNEL_CLOSE
[09:42:32.451] [NioProcessor-2] DEBUG RelaySessionSshChannelRecipient -
Received SSH_MSG_CHANNEL_CLOSE on channel 0
[09:42:32.452] [NioProcessor-2] DEBUG RelaySessionSshChannelRecipient - Send
SSH_MSG_CHANNEL_CLOSE on channel 0
[09:42:32.453] [NioProcessor-2] DEBUG RelaySessionSshChannelRecipient - Closing
channel 0 immediately
[09:42:32.452] [NioProcessor-3] DEBUG RelaySessionSshChannelRecipient - Send
SSH_MSG_CHANNEL_DATA on channel 0
[09:42:32.460] [NioProcessor-2] DEBUG
org.apache.sshd.client.session.ClientSessionImpl - Closing session
for reference, this is the remote log, it helps to more clearly show the
sequence of packets going to/from the local end:
[09:42:32.449] [NioProcessor-1] DEBUG RelaySession - networkSessionClosed
[09:42:32.450] [NioProcessor-1] DEBUG RelaySessionSshChannelSender - Send
SSH_MSG_CHANNEL_CLOSE on channel 0
[09:42:32.456] [NioProcessor-4] DEBUG SshSession - Received packet
SSH_MSG_CHANNEL_CLOSE
[09:42:32.456] [NioProcessor-4] DEBUG RelaySessionSshChannelSender - Received
SSH_MSG_CHANNEL_CLOSE on channel 0
[09:42:32.457] [NioProcessor-4] DEBUG SshSession - Received packet
SSH_MSG_CHANNEL_DATA
[09:42:32.457] [NioProcessor-4] WARN SshSession - Exception caught
org.apache.sshd.common.SshException: Received SSH_MSG_CHANNEL_DATA on unknown
channel 0
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