sftp functions hanging if connection to the server is lost

[Sagi Lisker <sagi.lisker@xxxxxxxxxxx>]

Hi,

I have developed a sample program which uses libssh to read a remote file.
The program iteratively calls sftp_open, then sftp_read and finally sftp_close.
After successful connection I have simulated a network disconnection by deactivating the remote machine network interface (ifconfig <interface> down) prior to each of the calls above (using debugger for determining the exact location in the code when the connection is lost).

Each of the functions above (sftp_open, sftp_read and sftp_close) hung for about 15 minutes before returning an error ("No route to host").
As far as I understood from other correspondences, the issue was resolved lately (please correct me if I'm wrong).

I'm developing on Red Hat 7 which has libssh 0.7.1 as its latest version, and using the latest libssh version available (0.8.7 as far as I know) is a bit problematic.
This is a very serious bug, as my program might hang for a very long time if the server is suddenly down.

My questions:

1.       Is it possible to apply the fix to libssh 0.7.1?

2.       Is there a workaround to this issue I could use? (e.g. forcing a timeout somehow, efficiently checking the connection to the remote machine is not lost, etc.)

3.       Is there a time limit to which the sftp functions can wait before returning an error?

Thanks,
Sagi
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