#!/usr/bin/perl
# $Id: axfr 1815 2020-10-14 21:55:18Z willem $
use strict;
use warnings;
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 my $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 my $rr (@$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 my $rr ($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
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