Re: Possible bug in ncat 6.01?

[David Fifield <david () bamsoftware com>]

On Tue, Sep 04, 2012 at 08:18:39AM -0500, Alex Weber wrote:
> Hi Hani/list,
>
> Sorry! I realize now that wasn't very detailed/helpful - I blame late +
> tired :)
> What's happening is we're sending quickly enough to exhaust that socket's
> send space and occasionally getting a -1, EAGAIN (you can see it in an
> strace) in the ncat_broadcast function. That function doesn't handle -1,
> EAGAIN and generically treats it as an error that can't be handled - it
> writes the error to the console and carries on, dropping any data that
> couldn't get sent that time.
> I've attached a patch to ncat_core.c - I just set each socket to blocking
> before the send, and back to non-blocking after the send. That may mean
> Ncat has to block for a moment when sending a lot of data, but I can't
> think of a better way to handle it.
> It also causes two extra syscalls per send per socket - I don't know if
> this will have an appreciable performance impact, just something to
> consider.

Thank you for looking into this. I adapted your patch and applied it. I
decided that anything that applies to ncat_broadcast should apply to
ncat_send equally, so I made an auxiliary function that does the
blocking and unblocking.

David Fifield
_______________________________________________
Sent through the nmap-dev mailing list
http://cgi.insecure.org/mailman/listinfo/nmap-dev
Archived at http://seclists.org/nmap-dev/