#!/usr/bin/perl -w

# Copyright (c) 2007 Ted Unangst
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

# Copies hostnames from a dhcpd leases file to named zone files
# Existing hosts or IPs are not updated
#
# Usage: lease2zone.pl dhcpd.leases zonefile.dom zonefile.dom.rev
# Then pkill -HUP named


use strict;

@ARGV == 3 or die "not enough arguments: leasefile zonefile reversezone";

# regexes for hostnames and ips
my $hregex = "[a-zA-Z0-9-]+";
my $iregex = "\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}";

my %clients; # dhcpd clients
my %hosts; # hostnames already governed by zone
my $domain; # domain name from $ORIGIN

# find all the clients
open(LEASEFILE, "<", $ARGV[0]) or die "can't open lease file";
my $ip; #temp var
while (<LEASEFILE>) {
	if (/lease\s($iregex)\s{/) {
		$ip = $1;
	} elsif (/client-hostname "($hregex)";/) {
		$clients{$ip} = $1;
	}
}
close(LEASEFILE);

foreach $ip (keys %clients) {
	#print "$ip is named $clients{$ip}\n";
}

# pass through zone files and remove clients with existing hostnames
open(ZONEFILE, "<", $ARGV[1]) or die "o";
while (<ZONEFILE>) {
	if (/^($hregex)\s+IN\s+A\s+($iregex)/) {
		delete($clients{$2});
		$hosts{$1} = $2;
	} elsif (/^\$ORIGIN\s+(($hregex\.)+)/) {
		#print "domain is $1\n";
		$domain = $1;
	}
}
close(ZONEFILE);
# same with rev zone file
open(ZONEFILE, "<", $ARGV[2]) or die "o";
while (<ZONEFILE>) {
	if (/^(\d+)\s+PTR\s+($hregex)/) {
		delete($clients{$1});
		$hosts{$2} = $1;
	}
}
close(ZONEFILE);

# we have the list of new client ips now
# do another sweep to remove taken hostnames
foreach $ip (keys %clients) {
	my $hostname = $clients{$ip};
	#print "new ip $ip is named $hostname ";
	if (defined($hosts{$hostname})) {
		#print "taken\n";
		delete($clients{$ip});
	} else {
		#print "new host\n";
	}
}

# add the new clients to the right files
open(ZONEFILE, ">>", $ARGV[1]) or die "can't append zone file";
foreach $ip (keys %clients) {
	my $hostname = $clients{$ip};
	print ZONEFILE "$hostname\tIN\tA\t$ip\n";
}
close(ZONEFILE);
open(ZONEFILE, ">>", $ARGV[2]) or die "can't append rev zone file";
foreach $ip (keys %clients) {
	my $hostname = $clients{$ip};
	$ip =~ s/\d+\.\d+\.\d+\.(\d+)/$1/;
	print ZONEFILE "$ip\t\tPTR\t$hostname.$domain\n";
}
close(ZONEFILE);