statistics/ans4/ans.pl

	ans.pl revision 0c27b3fe77ac1d5094ba3521e8142d9e7973133f
#!/usr/bin/perl -w
#
# Copyright (C) 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/.

# $Id$

#
# Ad hoc name server
#

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

my $sock = IO::Socket::INET->new(LocalAddr => "10.53.0.4",
   LocalPort => 5300, Proto => "udp") or die "$!";

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;

    if ($qname eq "foo.info") {
        $donotrespond = 1;
    } elsif ($qname eq "cname1.example.com") {
        # Data for the "cname + other data / 1" test
        $packet->push("answer", new Net::DNS::RR("cname1.example.com 300 CNAME cname1.example.com"));
        $packet->push("answer", new Net::DNS::RR("cname1.example.com 300 A 1.2.3.4"));
    } elsif ($qname eq "cname2.example.com") {
        # Data for the "cname + other data / 2" test: same RRs in opposite order
        $packet->push("answer", new Net::DNS::RR("cname2.example.com 300 A 1.2.3.4"));
        $packet->push("answer", new Net::DNS::RR("cname2.example.com 300 CNAME cname2.example.com"));
    } elsif ($qname eq "www.example.org" || $qname eq "www.example.net" ||
         $qname eq "badcname.example.org" ||
         $qname eq "goodcname.example.org" ||
         $qname eq "foo.baddname.example.org" ||
         $qname eq "foo.gooddname.example.org") {
        # Data for address/alias filtering.
        $packet->header->aa(1);
        if ($qtype eq "A") {
            $packet->push("answer",
                      new Net::DNS::RR($qname .
                               " 300 A 192.0.2.1"));
        } elsif ($qtype eq "AAAA") {
            $packet->push("answer",
                      new Net::DNS::RR($qname .
                        " 300 AAAA 2001:db8:beef::1"));
        }
    } elsif ($qname eq "badcname.example.net" ||
         $qname eq "goodcname.example.net") {
        # Data for CNAME/DNAME filtering.  We need to make one-level
        # delegation to avoid automatic acceptance for subdomain aliases
        $packet->push("authority", new Net::DNS::RR("example.net 300 NS ns.example.net"));
        $packet->push("additional", new Net::DNS::RR("ns.example.net 300 A 10.53.0.3"));
    } elsif ($qname =~ /^nodata\.example\.net$/i) {
        $packet->header->aa(1);
    } elsif ($qname =~ /^nxdomain\.example\.net$/i) {
        $packet->header->aa(1);
        $packet->header->rcode(NXDOMAIN);
    } elsif ($qname =~ /sub\.example\.org/) {
        # Data for CNAME/DNAME filtering.  The final answers are
        # expected to be accepted regardless of the filter setting.
        $packet->push("authority", new Net::DNS::RR("sub.example.org 300 NS ns.sub.example.org"));
        $packet->push("additional", new Net::DNS::RR("ns.sub.example.org 300 A 10.53.0.3"));
    } else {
        # Data for the "bogus referrals" test
        $packet->push("authority", new Net::DNS::RR("below.www.example.com 300 NS ns.below.www.example.com"));
        $packet->push("additional", new Net::DNS::RR("ns.below.www.example.com 300 A 10.53.0.3"));
    }

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