Milter-greylist

Hi,

I attach a patch that fixes a crash.

The crash can reproduce with the following greylist.conf:

  ...
  socket "inet:30025"
  user "nobody"
  ...

Run milter-greylist as root user:

  % sudo milter-greylist

milter-greylist will be crashed.

Points:

  * "socket" is not file path. (e.g. inet:XXX, unix:XXX and so on)
  * "user" has only user. Group should not be included like
  * Run milter-greylist as root user.

Cause:

If we run milter-greylist as root user and "user"
parameter value is specified, "socket" parameter value
is chown-ed to "user" parameter value. If "socket"
parameter value is not path like "inet:30025", chown()
is always failed. And error message is logged by the
following code:

  mg_log(LOG_WARNING, "%s: cannot change \"%s\""
      " ownership to %s/%s: %s", argv[0], 
      conf.c_socket, pw->pw_name, gr->gr_name,
      strerror(errno));

"gr->gr_name" is a problem. "gr" is NULL when "user"
parameter value doesn't have group such as "nobody".

Solutions:

  (a) Don't chown() when "socket" parameter value has scheme
      such as "inet", "inet6", "unix" and "local".
  (b) Set "gr" even if "user" parameter value doesn't have
      group. (The attached patch uses this solution.)

I think that we should apply both solutions but I attach
only (b) solution. Because (b) solves more effected
problem. "gr" is used other location too. (See
code around chown(conf.c_pidfile, ...).) (a) doesn't solve
the problem.

So I think that (b) should be fixed at first. I will send a
patch for (a) after this patch is applied.


Thanks,
--
kou