#!/usr/bin/perl
##### 
# bpa-check.pl - use to check current IP, and update a GnuDIP server if changed
# ------------
# Please check the following config items
#####

#sendmail or equivalent location
$sendmail = "/usr/lib/sendmail";

#email address to send notifications to 
# undef $email; # to disable sending email
$email = "email\@host";

# interface where dynamic IP (dhcp) is
$interface = "eth0";

# username for GnuDIP service
$username = "username";

# password for GnuDIP service
$password = "password";

# hostname handle for your host
$hosthandle = "handle"; 

# word to grep for on the ifconfig display
$grepword = "inet"; 

# file to use to store currently checked IP
$bpaipfile = "/etc/bpaipaddress";

# update command, will append the current IP address after this command (jddns3)
$updatecommand = "/usr/local/bin/jddns3 --user $username --pass $password set $hosthandle";
#uncomment this if you want to use the non java client
#$updatecommand = "/sbin/ddns3 -u $username -p $password -s $hosthandle";

#script to run if IP changes
# $script = "/usr/local/sbin/bind-restart.sh";
# undef $script; # to disable script running...

# change the ifconfig call if need be if it fails
$_ = `/sbin/ifconfig $interface | grep -w $grepword`;

#print $_;
(/inet ((\d{1,3}\.?){4})/m) ? ( $ipaddr = $1 ) : (warn 'ifconfig failed');
#print "$ipaddr\n";
print "\nUpdating dynamic dns...\n";
if (-s $bpaipfile)
{
  open(IN,$bpaipfile);
  while(<IN>)
  {
    $oldip = $_;
  }
  close(IN);
  #print "$oldip\n";
  if ($oldip ne $ipaddr)
  {
    print "No Match!!\n";
    $return = `$updatecommand $ipaddr`;
    print $return;
    if ( $return =~ m/OK/ || $return =~ m/ip is unchanged/sg )
    {
      open(OUT,">$bpaipfile");
      print OUT $ipaddr;
      close(OUT);
    }
    # send mail to notifer user that the IP has changed
    if ($email){
	    print "Sending notification to $email...\n";
	    open (MAIL, "|$sendmail $email");
	    print MAIL "Subject: IP changed on $hosthandle to $ipaddr\n\n";
	    print MAIL "$0 noticed your IP has changed...\n";
	    print MAIL "This is the new ip [$ipaddr]\n";
	    print MAIL "This is the old ip [$oldip]\n\n";
	    close (MAIL);
    }
    #run the command because of IP change
    if ($script ){
	exec $script;
    }
  }
}
else
{
	open(OUT,">$bpaipfile");
	print OUT $ipaddr;
	close(OUT);
}

print "This is the new ip [$ipaddr]\n";
print "This is the old ip [$oldip]\n\n";