ans.pl revision bf8267aa453e5d2a735ed732a043b77a0b355b20
#!/usr/bin/perl -w
#
# Copyright (C) 2012 Internet Systems Consortium, Inc. ("ISC")
#
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
# OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
# PERFORMANCE OF THIS SOFTWARE.
# $Id$
#
# 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, $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";
}
}