/* Domain name validation.
   Copyright (C) 2006, 2007 Jan Rafaj

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
   MA 02110-1301 USA */

#require dns

#  boolean valid_domain (string DOMAIN)
# 
# Returns true if the domain name DOMAIN has a
# corresponding A record or if it has any MX records, that is if it can
# be possible to send mail to it.
# 
func valid_domain(string domain) returns number
do
    return not (resolve(%domain) = "0" and not hasmx(%domain))
done