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Re: [nmap-svn] r32398 - in nmap: ncat nsock/src
From: Henri Doreau <henri.doreau () gmail com>
Date: Fri, 27 Sep 2013 10:16:15 +0200

2013/9/26  <commit-mailer () nmap org>:
Author: david
Date: Thu Sep 26 07:17:08 2013
New Revision: 32398

Log:
Use tempfile in place of tempnam.

To avoid new GCC warnings about tempnam:
ncat_connect.c:789: warning: the use of `tempnam' is dangerous, better use `mkstemp'

Doing things this way has the same race condition as tempnam did,
because we are unlinking the file before binding it. (The race window is
smaller now.) The file must not exist before binding the Unix socket, or
else you get an "address already in use" error. Unlinking before binding
is the same thing that netcat-openbsd does. See this earlier thread:
http://seclists.org/nmap-dev/2012/q4/336.

[...]
-  nsock_log_info(ms, "Binding to %s (IOD #%li)", get_localaddr_string(iod), iod->id);
+  path = get_localaddr_string(iod);
+  unlink(path);
+  nsock_log_info(ms, "Binding to %s (IOD #%li)", path, iod->id);
   rc = bind(iod->sd, (struct sockaddr *)&iod->local, (int) iod->locallen);

Hi David,

I have a couple comments on this patch too.

Calling unlink() unconditionally seems wrong to me, we should only do
it when dealing with unix sockets. I wouldn't like nmap to delete my
files just because they're called "127.0.0.1:8080" or something...

It's almost cosmetic but I would also move the nsock_log statement
before the unlink, so that it's very obvious that the race window is
minimal.

Regards

-- 
Henri
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