Re: Library blocks in call to poll

[Aris Adamantiadis <aris@xxxxxxxxxxxx>]

Hi Joao,

I'm sorry your patch was forgotten. I reviewed it and committed it in
both master and v0-6.

Thanks!

Aris
Le 11/02/15 20:04, Joao Pedro Almeida Pereira a écrit :
> Hello,
> Was this patch ever reviewed? Or added to the master?
>
> BR
>
> On Thu, Jul 31, 2014 at 2:55 PM, Joao Pedro Almeida Pereira
> <joao.almeida@xxxxxxxxxxx <mailto:joao.almeida@xxxxxxxxxxx>> wrote:
>
>     Hello,
>     I am seeing a behaviour in the library that is strange and due to
>     a return value that is not being retrieved.
>     The behaviour is the following
>     1 - Create a shell channel
>     2 - write and read a bunch of commands
>     3 - Wait 10 minutes without traffic
>     4 - Try to disconnect the channel
>     4 - Read the output but the output is an EOF and the channel closes
>     5 - After that the poll is called to flush the rest of the packets
>     from the socket and will never leave this function because we get
>     a Broken Pipe in the connection
>
>     I am using linux and the library version 0.6.3
>
>     This is the log of the library:
>
>     [2014/07/31 11:06:16.326721, 3] ssh_socket_unbuffered_write:
>      Enabling POLLOUT for socket
>     [2014/07/31 11:06:16.326741, 3] packet_send2:  packet: wrote
>     [len=12,padding=6,comp=5,payload=5]
>     [2014/07/31 11:06:16.326750, 3] ssh_channel_send_eof:  Sent a EOF
>     on client channel (43:0)
>     [2014/07/31 11:06:16.326770, 3] packet_send2:  packet: wrote
>     [len=12,padding=6,comp=5,payload=5]
>     [2014/07/31 11:06:16.326779, 3] ssh_channel_close:  Sent a close
>     on client channel (43:0)
>     [2014/07/31 11:06:16.326806, 3] ssh_packet_socket_callback:
>      packet: read type 96 [len=12,padding=6,comp=5,payload=5]
>     [2014/07/31 11:06:16.326816, 3] ssh_packet_process:  Dispatching
>     handler for packet type 96
>     [2014/07/31 11:06:16.326827, 3] channel_rcv_eof:  Received eof on
>     channel (44:1)
>     [2014/07/31 11:06:16.326835, 3] ssh_packet_socket_callback:
>      Processing 244 bytes left in socket buffer
>     [2014/07/31 11:06:16.326850, 3] ssh_packet_socket_callback:
>      packet: read type 98 [len=44,padding=5,comp=38,payload=38]
>     [2014/07/31 11:06:16.326858, 3] ssh_packet_process:  Dispatching
>     handler for packet type 98
>     [2014/07/31 11:06:16.326870, 3] channel_rcv_request:  Remote
>     connection closed by signal SIG TERM 
>     [2014/07/31 11:06:16.326878, 3] ssh_packet_socket_callback:
>      Processing 176 bytes left in socket buffer
>     [2014/07/31 11:06:16.326891, 3] ssh_packet_socket_callback:
>      packet: read type 97 [len=12,padding=6,comp=5,payload=5]
>     [2014/07/31 11:06:16.326899, 3] ssh_packet_process:  Dispatching
>     handler for packet type 97
>     [2014/07/31 11:06:16.326907, 3] channel_rcv_close:  Received close
>     on channel (44:1)
>     [2014/07/31 11:06:16.326914, 3] ssh_packet_socket_callback:
>      Processing 140 bytes left in socket buffer
>     [2014/07/31 11:06:16.326927, 3] ssh_packet_socket_callback:
>      packet: read type 96 [len=12,padding=6,comp=5,payload=5]
>     [2014/07/31 11:06:16.326935, 3] ssh_packet_process:  Dispatching
>     handler for packet type 96
>     [2014/07/31 11:06:16.326943, 3] channel_rcv_eof:  Received eof on
>     channel (43:0)
>     [2014/07/31 11:06:16.326950, 3] ssh_packet_socket_callback:
>      Processing 104 bytes left in socket buffer
>     [2014/07/31 11:06:16.326963, 3] ssh_packet_socket_callback:
>      packet: read type 98 [len=44,padding=5,comp=38,payload=38]
>     [2014/07/31 11:06:16.326971, 3] ssh_packet_process:  Dispatching
>     handler for packet type 98
>     [2014/07/31 11:06:16.326980, 3] channel_rcv_request:  Remote
>     connection closed by signal SIG TERM 
>     [2014/07/31 11:06:16.326988, 3] ssh_packet_socket_callback:
>      Processing 36 bytes left in socket buffer
>     [2014/07/31 11:06:16.327001, 3] ssh_packet_socket_callback:
>      packet: read type 97 [len=12,padding=6,comp=5,payload=5]
>     [2014/07/31 11:06:16.327009, 3] ssh_packet_process:  Dispatching
>     handler for packet type 97
>     [2014/07/31 11:06:16.327016, 3] channel_rcv_close:  Received close
>     on channel (43:0)
>     [2014/07/31 11:06:16.327044, 3] ssh_socket_unbuffered_write:
>      Enabling POLLOUT for socket
>     [2014/07/31 11:06:16.327066, 1] ssh_socket_nonblocking_flush:
>      Writing packet: error on socket (or connection closed): Broken pipe
>
>
>     This is the library back trace:
>
>     #0  0x00007ff8e99cc4bf in poll () from /lib64/libc.so.6
>     #1  0x00007ff8e426fceb in ssh_poll_ctx_dopoll () from
>     /usr/lib64/libssh.so.4
>     #2  0x00007ff8e4270121 in ssh_handle_packets () from
>     /usr/lib64/libssh.so.4
>     #3  0x00007ff8e427038a in ssh_handle_packets_termination () from
>     /usr/lib64/libssh.so.4
>     #4  0x00007ff8e427051a in ssh_blocking_flush () from
>     /usr/lib64/libssh.so.4
>     #5  0x00007ff8e425e476 in ssh_channel_close () from
>     /usr/lib64/libssh.so.4
>
>
>     The problem that i found is that the
>     function ssh_socket_nonblocking_flush when is called the library
>     do not check if an error happened and follow the stream without
>     looking into it an so when the poll is done in the socket it gets
>     stuck.
>
>     To solve the following issue i created the attached patch that
>     correct some points present in the socket.c that had "FIXME" tags
>     on them, and now the problem is solved.
>
>     If you see any issue please tell me.
>
>     BR 
>     --
>     -----
>     --------
>     João Pereira
>
>     Email: joao.almeida@xxxxxxxxxxx <mailto:joao.almeida@xxxxxxxxxxx>
>     Web: http://www.bluetc.es <http://www.bluetc.es/>
>
>
>
>
> -- 
> --
> -----
> --------
> João Pereira
>
> Email: joao.almeida@xxxxxxxxxxx <mailto:joao.almeida@xxxxxxxxxxx>
> Web: http://www.bluetc.es <http://www.bluetc.es/>