#!/usr/bin/perl

my $zoneFile = "/Users/ian/dns/db.ian";
my $ipLog    = "/Users/ian/dns/iplog.txt";

my @ipdata   = `/usr/local/bin/noip2 -S 2>&1`;

# get IP
foreach(@ipdata) {
	if ($_ =~ /\b(?:\d{1,3}\.){3}\d{1,3}\b/) { $ip = $&; }
}

# read zone file
open(ZONE, "$zoneFile");
my @zoneData = <ZONE>;
close(ZONE);

foreach(@zoneData) 
{
	# replace IP references
	$_ =~ s/\b(?:\d{1,3}\.){3}\d{1,3}\b/$ip/g;

	# find zone serial number
	if ($_ =~ m/([0-9]{10}).*serial/g) 
	{
		$serial = $1;

		# get date
		($Second, $Minute, $Hour, $Day, $Month, $Year)
			= localtime(time);

		$Year = 1900 + $Year;
		$Month++;

		if (length($Day) == 1)   { $Day   = "0" . $Day;   }
		if (length($Month) == 1) { $Month = "0" . $Month; }

		# if date has changed then set new date and version 01
		# else if date is the same then just increment serial

		if (substr($serial, 0, 8) eq "$Year$Month$Day") 
		{
			$serial++;
			$_ =~ s/[0-9]{10}/$serial/g;
		}

		else
		{
			my $newSerial = "$Year$Month$Day" . "01";
			$_ =~ s/[0-9]{10}/$newSerial/g;
		}
	}
}

# write new file
open(ZONE, ">$zoneFile");
print ZONE @zoneData;
close(ZONE);

# write to log

if ($ipLog ne "")
{
	open(LOG, ">>$ipLog");
	print LOG "$Year-$Month-$Day $Hour:$Minute --> changed to $ip\n";
	close(LOG);
}

# kick BIND

`rndc reload`;