rpzrecurse/ans5/ans.pl

#!/usr/bin/perl -w
#
# Copyright (C) 2016  Internet Systems Consortium, Inc. ("ISC")
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

use IO::File;
use IO::Socket;
use Net::DNS;
use Net::DNS::Packet;

my $sock = IO::Socket::INET->new(LocalAddr => "10.53.0.5",
   LocalPort => 5300, Proto => "udp") or die "$!";

my $pidf = new IO::File "ans.pid", "w" or die "cannot open pid file: $!";
print $pidf "$$\n" or die "cannot write pid file: $!";
$pidf->close or die "cannot close pid file: $!";
sub rmpid { unlink "ans.pid"; exit 1; };

$SIG{INT} = \&rmpid;
$SIG{TERM} = \&rmpid;

for (;;) {
    $sock->recv($buf, 512);

    print "**** request from " , $sock->peerhost, " port ", $sock->peerport, "\n";

    my $packet;

    if ($Net::DNS::VERSION > 0.68) {
        $packet = new Net::DNS::Packet(\$buf, 0);
        $@ and die $@;
    } else {
        my $err;
        ($packet, $err) = new Net::DNS::Packet(\$buf, 0);
        $err and die $err;
    }

    print "REQUEST:\n";
    $packet->print;

    $packet->header->qr(1);

    my @questions = $packet->question;
    my $qname = $questions[0]->qname;
    my $qtype = $questions[0]->qtype;

    my $donotrespond = 0;

    $packet->header->aa(1);
    if ($qtype eq "A") {
        $packet->push("answer",
                  new Net::DNS::RR($qname .
                           " 300 A 10.53.0.5"));
    #} elsif ($qtype eq "AAAA") {
        #$packet->push("answer",
                  #new Net::DNS::RR($qname .
                    #" 300 AAAA 2001:db8:beef::1"));
    } elsif ($qtype eq "NS") {
        $donotrespond = 1;
    }

    if ($donotrespond == 0) {
        $sock->send($packet->data);
        print "RESPONSE:\n";
        $packet->print;
        print "\n";
    } else {
        print "DROP:\n";
    }
}