Re: Hangs when downloading large files

[Andreas Schneider <mail@xxxxxxxxxxxx>]

On Tuesday 09 March 2010 18:05:21 you wrote:
> Andreas,
> 
> It didn't work to add "-l DEBUG2" to Subsystem--it complained about
> "garbage (-l)" at the end of the line. My path is slightly different,
> though:
> 
>   Subsystem       sftp    /usr/libexec/openssh/sftp-server
> 
> so maybe this has to do with the version. I tried adding "LogLevel
> DEBUG2" to the file, though, and it seems to have worked--at least, I
> get what looks like level-2 debugging from the server. I've attached the
> server's debug output, and Sawmill+libssh debug output.

If you set it the variable in the config file you enable debug logging of 
sshd.

Take a look in 'man sftp_server'. I've set

Subsystem       sftp    /usr/lib64/ssh/sftp-server -l DEBUG2

and restarted sshd. I got a lot of debugging output from the sftp server.

To enable logging in libssh you have to set:

int verbosity = SSH_LOG_FUNCTIONS;
ssh_set_options(session, SSH_OPTIONS_LOG_VERBOSITY, &verbosity);
 
> If this is a server bug, I will be content to just document it,
> especially if there's a newer version of the server which fixes it. Do
> you know if there is?

That's what we should confirm. It is possible that it is a bug in libssh.
 
> I don't understand the sshfs code enough to know what we would have to
> do similarly. Is this a change that would be made in libssh, or is this
> a change I could make in my client program? I suspect the former; it
> seems to have to do with throttling the amount of outstanding data
> somehow, and I don't think the libssh API provides any functionality for
> determining what's outstanding. Is there some way I can implement this
> on my end?

Lets look at the logs and then we can try to create a testcase for it.


	-- andreas