#!/usr/bin/perl -w

# $Id: axfr 264 2005-04-06 09:16:15Z olaf $

use strict;

use vars qw($opt_f $opt_q $opt_s $opt_D);

use File::Basename;

use Getopt::Std;

use Net::DNS;

use Storable;

#------------------------------------------------------------------------------

# Read any command-line options and check syntax.

#------------------------------------------------------------------------------

getopts("fqsD:");

die "Usage: ", basename($0), " [ -fqs ] [ -D directory ] [ \@nameserver ] zone\n"

	unless (@ARGV >= 1) && (@ARGV <= 2);

#------------------------------------------------------------------------------

# Get the nameserver (if specified) and set up the zone transfer directory

# hierarchy.

#------------------------------------------------------------------------------

my $nameserver = ($ARGV[0] =~ /^@/) ? shift @ARGV : "";

$nameserver =~ s/^@//;

my $zone = shift @ARGV;

my $basedir = defined $opt_D ? $opt_D : $ENV{"HOME"} . "/.dns-zones";

my $zonedir = join("/", reverse(split(/\./, $zone)));

my $zonefile = $basedir . "/" . $zonedir . "/axfr";

# Don't worry about the 0777 permissions here - the current umask setting

# will be applied.

unless (-d $basedir) {

	mkdir($basedir, 0777) or die "can't mkdir $basedir: $!\n";

}

my $dir = $basedir;

my $subdir;

foreach $subdir (split(m#/#, $zonedir)) {

	$dir .= "/" . $subdir;

	unless (-d $dir) {

		mkdir($dir, 0777) or die "can't mkdir $dir: $!\n";

	}

}

#------------------------------------------------------------------------------

# Get the zone.

#------------------------------------------------------------------------------

my $res = Net::DNS::Resolver->new;

$res->nameservers($nameserver) if $nameserver;

my (@zone, $zoneref);

if (-e $zonefile && !defined $opt_f) {

	$zoneref = retrieve($zonefile) || die "couldn't retrieve zone from $zonefile: $!\n";

	#----------------------------------------------------------------------

	# Check the SOA serial number if desired.

	#----------------------------------------------------------------------

	if (defined $opt_s) {

		my($serial_file, $serial_zone);

		my $rr;

		foreach $rr (@$zoneref) {

			if ($rr->type eq "SOA") {

				$serial_file = $rr->serial;

				last;

			}

		}

		die "no SOA in $zonefile\n" unless defined $serial_file;

		my $soa = $res->query($zone, "SOA");

		die "couldn't get SOA for $zone: ", $res->errorstring, "\n"

			unless defined $soa;

		foreach $rr ($soa->answer) {

			if ($rr->type eq "SOA") {

				$serial_zone = $rr->serial;

				last;

			}

		}

		if ($serial_zone != $serial_file) {

			$opt_f = 1;

		}

	}

} else {

	$opt_f = 1;

}

if (defined $opt_f) {

	@zone = $res->axfr($zone);

	die "couldn't transfer zone: ", $res->errorstring, "\n" unless @zone;

	store \@zone, $zonefile or die "couldn't store zone to $zonefile: $!\n";

	$zoneref = \@zone;

}

#------------------------------------------------------------------------------

# Print the records in the zone.

#------------------------------------------------------------------------------

unless ($opt_q) {

	$_->print for @$zoneref

}

__END__

=head1 NAME

axfr - Perform a DNS zone transfer

=head1 SYNOPSIS

B<axfr> S<[ B<-fqs> ]> S<[ B<-D> I<directory> ]> S<[ B<@>I<nameserver> ]>

I<zone>

=head1 DESCRIPTION

B<axfr> performs a DNS zone transfer, prints each record to the standard

output, and stores the zone to a file.  If the zone has already been

stored in a file, B<axfr> will read the file instead of performing a

zone transfer.

Zones will be stored in a directory hierarchy.  For example, the

zone transfer for foo.bar.com will be stored in the file

$HOME/.dns-zones/com/bar/foo/axfr.  The directory can be changed

with the B<-D> option.

This programs requires that the Storable module be installed.

=head1 OPTIONS

=over 4

=item B<-f>

Force a zone transfer, even if the zone has already been stored

in a file.

=item B<-q>

Be quiet -- don't print the records from the zone.

=item B<-s>

Perform a zone transfer if the SOA serial number on the nameserver

is different than the serial number in the zone file.

=item B<-D> I<directory>

Store zone files under I<directory> instead of the default directory

(see L<"FILES">).

=item B<@>I<nameserver>

Query I<nameserver> instead of the default nameserver.

=back

=head1 FILES

=over 4

=item B<$HOME/.dns-zones>

Default directory for storing zone files.

=back

=head1 AUTHOR

Michael Fuhr <mike@fuhr.org>

=head1 SEE ALSO

L<perl(1)>, L<check_soa>, L<check_zone>, L<mresolv>, L<mx>, L<perldig>,

L<Net::DNS>, L<Storable>

=cut