#!/usr/bin/perl
# Copyright 2005 Thomas A. Limoncelli
# 
#     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 of the License, 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

# canonzone [domain]
#   Purpose: Cannonicalize a zone file so that dumber scripts can have
#				an easier time parsing it.
#	Input: A real zone file with many formatting nasties.
#	Output: The zone file with one RR per line
#				$ORIGIN's removed
#				$TTL's removed
#				$INCLUDE's replaced with the file's contents
#				Lines that include TTL's have TTL's removed.
#				Lines that begin with whitespace turning into regular RR's
#				All hostnames turned into FQDN's (with exception listed below)
#				If a FQDN ends with [domain], it is removed.
#				Output in a strict format of:
#						HOSTNAME.domain.<TABS>IN<SPACE>TYPE<TAB>DATA\n
#				or for hosts in the [domain]:
#						HOSTNAME<TABS>IN<SPACE>TYPE<TAB>DATA\n
#
#	Defaults:
#		If "domain" is left off the command line, we assume "bell-labs.com."

#
# TODO:
#   Handle $GENERATE better.  Include an option that expands the hosts.
#

if ($ARGV[0] =~ /-n/) {
	shift @ARGV;
	$nostripend = 1;
}

# our defaults
$origin   = 'cibernet.com.';
$origin = shift @ARGV if defined($ARGV[0]);

$stripend = $origin; $stripend =~ s/(\.)/\\$1/g;
#print STDERR "; $origin $stripend\n";

die "ARGV[1] $stripend does not end in ." unless $stripend =~ /\.$/;
die "ARGV[1] $origin does not end in ." unless $origin =~ /\.$/;

# intialize things
$defname = '';
$host = '';
#$noprevioushost = 1;

&doit(STDIN);

sub doit {
	local(*FILE) = @_;
	while (<FILE>) {

		# process whitespace, comments, and continuations:
		chomp;
		# the order of the next three lines is very important
		s/;.*//;        # toss comments
		next if /^\s*$/;        # skip blank lines
		redo if ( /\(/ && ! /\)/ ) && ($_ .= <>);     # handle continuations

		# Handle the meta stuff:
		if (/^\$ORIGIN\s+/) {		# handle the $ORIGIN statements
			($junk, $origin, @junk) = split;
#			$noprevioushost = 1;
			die "ORIGIN $origin does not end in ." unless $origin =~ /\.$/;
			chomp;
			next;
		} elsif (/^\$GENERATE\s+/) {	# handle the $GENERATE statement
			s/\s+/ /g;	# change whitespace to a single space
			print; print "\n";
			next;
		} elsif (/^\$TTL\s+/) {	# handle the $TTL statement
			# do nothing
			next;
		} elsif (/^\$INCLUDE\s+/) {	# handle the $INCLUDE statements
			($junk, $filename, @junk) = split;
			die "INCLUDE file doesn't exist" unless -f $filename;
			print "; INCLUDE BEGIN $filename\n";
			open(INCFILE, "<" . $filename) || die "Can not read $filename: $!";
			&doit(INCFILE);
			close INCFILE;
			print "; INCLUDE END   $filename\n";
			next;
		} elsif (/^\$/) {
			die "ERROR1: I don't understand this \$ line: $_\n";
		}

		# ASSERTION at this point we know the line is just a RR.

		# if the line begins with whitespace, prepend the last host.
		# BUG: this may not handle "last host" across $INCLUDEs properly
		if (/^\s/)	{		# line begins with whitespace
			$_ = $defname . " " . $_;
		}

		# Extract the host, type, and data from the RR:
		if (/(\S+)\s+(\d*)\s+IN\s+(\S+)\s+(.*)/i) { # host ttl IN rrtype data
			($h, $junk, $TYPE, $data) = ($1, $2, $3, $4);
			#print "read: HOST:$h JUNK:$junk TYPE:$TYPE DATA:$data\n";
		} elsif (/(\S+)\s+IN\s+(\S+)\s+(.*)/i) { # host IN rrtype data
			($h, $TYPE, $data) = ($1, $2, $3);
			#print "read: HOST:$h TYPE:$TYPE DATA:$data\n";
		} elsif (/(\S+)\s+(\S+)\s+(.*)/i) { # host IN rrtype data
			($h, $TYPE, $data) = ($1, $2, $3);
			#print "read: HOST:$h TYPE:$TYPE DATA:$data\n";
		} else {
			die "ERROR2: I don't understand this line:\n$_\n";
		}

		$h = $origin if $h eq '@';		# "@" is shorthand for the origin

		# if the hostname is not a FQDN, append the $origin
		if ( $h =~ /\.$/ ) {
			$host = $h;
		} else {
			$host = $h . "." . $origin;
		}

		$defname = $host;	# record what will be the next line's default hostname

		# remove the domain we are stripping the zone:
		$host =~ s/\.$stripend$//i unless $nostripend;

		# Format and print the RR:
		$TAB = ''; $TAB = "\t" if length($host) < 8;
		print "${host}\t${TAB}IN ${TYPE}\t$data\n";

	}
}