ncat datagram connect only if not in recvonly mode

[glicht]

I am trying to use ncat to listen on a unix domain datagram socket in
receive only mode. I am using this as a simple syslog receiving server for
testing.

When I use the following command:

ncat --recv-only -luU /tmp/test.socket

and then try to log a message using logger with the following command:

logger -d -u /tmp/test.socket "this is a test"

I get the following error on the ncat side:

connect: Invalid argument

From looking at the ncat_listen.c code it looks like ncat tries to connect
a sending socket even when in recv-only mode. I added a check to connect
only when not in recv-only mode and then ncat worked as expected.

I've also sent this out a few days back to the dev mailing list: http://seclists.org/nmap-dev/2014/q4/343 .

Hope this fix is something you can merge in.

Thanks,

Guy

[dmiller-nmap]

This is not really the correct way to handle this: Ncat crashes even without --recv-only. The reason is that logger does not bind its socket to a filename before sending, meaning that it is an unnamed socket. Ncat just can't handle that right now. I'm adding a bug (#46) for this, since it is a legit problem. Also see my reply to your dev list message.