#!/usr/bin/perl -nl
#
# $Id: check-mx.pl,v 1.2 2003/01/13 05:28:42 jmates Exp $
#
# Copyright (c) 2002, Jeremy Mates.  This script is free software;
# you can redistribute it and/or modify it under the same terms as
# Perl itself.
#
# Looks for potentially improperly terminated MX records in BIND zone
# files.
#
# Usage: check-mx.pl zonefile [... zonefileN]

# pull out MX target for consideration
if (m/IN\s+MX\s+\d+\s+(.+?)\s*$/) {
  $mx = $1;

  # look for MX targets containing dots without a trailing dot
  if ($mx =~ m/\.[^\z]/ and $mx !~ m/\.$/) {
    print "$ARGV:$.:$_";
  }
}

# reset line counter for proper multi-file operation
close ARGV if eof;

=head1 POD

Validates zone files by looking for MX records that contain what look
like other domain names without trailing dots, which often expand out
to bogus names like host.example.edu.example.edu:

  $ cat zonefile
        IN      MX      7       goodmx.example.edu.
        IN      MX      7       badmx.example.edu
        IN      MX      7       defaultzonemx
  $ ./check-mx.pl zonefile
  zonefile:2:     IN      MX      7       badmx.example.edu

=cut