#!/usr/bin/perl -w
# Update dyndns.dk by Ian Kumlien <pomac@vapor.com>
# No more running a browser every hour, check the ip first....
#
# Usage, copy the file to /etc/cron.hourly/
#
# don't forget to create the /var/dyndns/ directory
#

use IO::Socket;
use IO::Interface ':functions';
require LWP::UserAgent;

# usernane?
my $name = "";
# password?
my $password = "";
my $url = "http://dyndns.dk/opdat";
# what networking card?
my $if = "eth0";
# force update in how many days?
my $days = 3;

# ----------------------------------------------------------------------------
# Don't edit here unless you know what you are doing.
# ----------------------------------------------------------------------------

my $s = IO::Socket::INET->new(Proto => 'udp');
my ($fh, $ua, $res);
my $old_ip = "0.0.0.0";

if(open($fh, "/var/dyndns/addr-$if")) { 
	unless ((time - (stat($fh))[9]) > ($days * 86400)) {
		sysread($fh, $old_ip, '17');
	}
	close($fh);
}
unless($s->if_addr($if) eq $old_ip) {
	print "Not matching, starting update\n";
	$ua = new LWP::UserAgent;
	$ua->timeout(60);
	$res = $ua->get("$url?name=$name&pw=$password&silent=1");
	unless($res->is_error) {
		print "Update succeded!\n";
		if(open($fh, '>', "/var/dyndns/addr-$if")) {
			syswrite($fh, $s->if_addr($if));
			close($fh);
		}
	}
}