resolver/ans3/ans.pl

#!/usr/bin/perl
#
# Copyright (C) 2000, 2001, 2004, 2007, 2009, 2012, 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/.

# $Id: ans.pl,v 1.12 2009/11/04 02:15:30 marka Exp $

#
# Ad hoc name server
#

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

my $sock = IO::Socket::INET->new(LocalAddr => "10.53.0.3",
   LocalPort => 5300, Proto => "udp") or die "$!";

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

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

    if ($qname eq "badcname.example.net") {
        $packet->push("answer",
                  new Net::DNS::RR($qname .
                       " 300 CNAME badcname.example.org"));
    } elsif ($qname eq "foo.baddname.example.net") {
        $packet->push("answer",
                  new Net::DNS::RR("baddname.example.net" .
                       " 300 DNAME baddname.example.org"));
    } elsif ($qname eq "foo.gooddname.example.net") {
        $packet->push("answer",
                  new Net::DNS::RR("gooddname.example.net" .
                       " 300 DNAME gooddname.example.org"));
    } elsif ($qname eq "goodcname.example.net") {
        $packet->push("answer",
                  new Net::DNS::RR($qname .
                       " 300 CNAME goodcname.example.org"));
    } elsif ($qname eq "cname.sub.example.org") {
        $packet->push("answer",
                  new Net::DNS::RR($qname .
                       " 300 CNAME ok.sub.example.org"));
    } elsif ($qname eq "ok.sub.example.org") {
        $packet->push("answer",
                  new Net::DNS::RR($qname . " 300 A 192.0.2.1"));
    } elsif ($qname eq "www.dname.sub.example.org") {
        $packet->push("answer",
                  new Net::DNS::RR("dname.sub.example.org" .
                       " 300 DNAME ok.sub.example.org"));
    } elsif ($qname eq "www.ok.sub.example.org") {
        $packet->push("answer",
                  new Net::DNS::RR($qname . " 300 A 192.0.2.1"));
    } else {
        $packet->push("answer", new Net::DNS::RR("www.example.com 300 A 1.2.3.4"));
    }

    $sock->send($packet->data);

    print "RESPONSE:\n";
    $packet->print;
    print "\n";
}