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https://issues.apache.org/jira/browse/SSHD-1158?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17339819#comment-17339819
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Thomas Wolf commented on SSHD-1158:
-----------------------------------
[PR 191|https://github.com/apache/mina-sshd/pull/191]
> Channel closed by peer: extra SSH_MSG_CHANNEL_EOF sent
> ------------------------------------------------------
>
> Key: SSHD-1158
> URL: https://issues.apache.org/jira/browse/SSHD-1158
> Project: MINA SSHD
> Issue Type: Bug
> Affects Versions: 2.6.0, 2.7.0
> Reporter: Thomas Wolf
> Priority: Minor
>
> I observe the following:
> {code:java}
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> ChannelExec:528 - handleClose(ChannelExec[id=0,
> recipient=0]-JGitClientSession[[email protected]/104.192.141.1:22])
> SSH_MSG_CHANNEL_CLOSE
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> ChannelExec:533 - handleClose(ChannelExec[id=0,
> recipient=0]-JGitClientSession[[email protected]/104.192.141.1:22]) prevent
> sending EOF
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> ChannelExec:107 - close(ChannelExec[id=0,
> recipient=0]-JGitClientSession[[email protected]/104.192.141.1:22]) Closing
> gracefully
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> ChannelExec:666 - close(ChannelExec[id=0,
> recipient=0]-JGitClientSession[[email protected]/104.192.141.1:22]) prevent
> sending EOF
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> Window:356 - Closing Window[client/local](ChannelExec[id=0,
> recipient=0]-JGitClientSession[[email protected]/104.192.141.1:22])
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> Window:356 - Closing Window[client/remote](ChannelExec[id=0,
> recipient=0]-JGitClientSession[[email protected]/104.192.141.1:22])
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> ChannelExec:901 - sendEof(ChannelExec[id=0,
> recipient=0]-JGitClientSession[[email protected]/104.192.141.1:22])
> SSH_MSG_CHANNEL_EOF (state=Graceful)
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> JGitClientSession:1215 -
> encode(JGitClientSession[[email protected]/104.192.141.1:22]) packet #14
> sending command=96[SSH_MSG_CHANNEL_EOF] len=5
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> Nio2Session:171 - writeBuffer(Nio2Session[local=/192.168.2.83:58913,
> remote=bitbucket.org/104.192.141.1:22]) writing 68 bytes
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> AbstractChannel$GracefulChannelCloseable:594 - close(ChannelExec[id=0,
> recipient=0]-JGitClientSession[[email protected]/104.192.141.1:22])[immediately=false]
> processing
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> AbstractChannel$GracefulChannelCloseable:602 - close(ChannelExec[id=0,
> recipient=0]-JGitClientSession[[email protected]/104.192.141.1:22])[immediately=false]
> send SSH_MSG_CHANNEL_CLOSE
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> JGitClientSession:1215 -
> encode(JGitClientSession[[email protected]/104.192.141.1:22]) packet #15
> sending command=97[SSH_MSG_CHANNEL_CLOSE] len=5
> 2021-04-30 17:03:39 DEBUG sshd-JGitSshClient[7c440ee8]-nio2-thread-3
> Nio2Session:171 - writeBuffer(Nio2Session[local=/192.168.2.83:58913,
> remote=bitbucket.org/104.192.141.1:22]) writing 68 bytes
> {code}
> * Client receives a SSH_MSG_CHANNEL_CLOSE from the server
> * Client logs (twice) is wouldn't send an EOF
> * Client sends SSH_MSG_CHANNEL_EOF all the same
> * Client sends SSH_MSG_CHANNEL_CLOSE
> In my reading of [RFC 4254, section
> 5.3|https://tools.ietf.org/html/rfc4254#section-5.3], this is wrong; the RFC
> says:
> {quote}Upon receiving this message, a party *MUST* send back an
> SSH_MSG_CHANNEL_CLOSE unless it has already sent this message for the
> channel. [...] A party MAY send SSH_MSG_CHANNEL_CLOSE without having sent or
> received SSH_MSG_CHANNEL_EOF.
> {quote}
> I take this to mean that on reception of a CLOSE one needs to reply CLOSE,
> not EOF followed by CLOSE.
> IMO {{AbstractChannel.handleClose()}} should not call {{isEofSent()}} but use
> {{eofSent.getAndSet(true)}} instead to really prevent sending the EOF.
> That code got changed in SSHD-836 (commit
> [bba23bf70|https://github.com/apache/mina-sshd/commit/bba23bf70bcd7e4d5a972806a9df62669e7cda81#diff-e9d125fde1660adf395b423e4e0831b4ad9092ddf73fe8285a9706fa4b74d030R540]).
> What was the reason for that? [~gnodet], do you remember?
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