1#!/usr/bin/env perl
2#
3# Copyright (C) 2014  Internet Systems Consortium, Inc. ("ISC")
4#
5# Permission to use, copy, modify, and/or distribute this software for any
6# purpose with or without fee is hereby granted, provided that the above
7# copyright notice and this permission notice appear in all copies.
8#
9# THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
10# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11# AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14# OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15# PERFORMANCE OF THIS SOFTWARE.
16
17use strict;
18use warnings;
19
20use IO::File;
21use Getopt::Long;
22use Net::DNS::Nameserver;
23
24my $pidf = new IO::File "ans.pid", "w" or die "cannot open pid file: $!";
25print $pidf "$$\n" or die "cannot write pid file: $!";
26$pidf->close or die "cannot close pid file: $!";
27sub rmpid { unlink "ans.pid"; exit 1; };
28
29$SIG{INT} = \&rmpid;
30$SIG{TERM} = \&rmpid;
31
32my $count = 0;
33my $send_response = 0;
34
35my $localaddr = "10.53.0.4";
36my $localport = 5300;
37my $verbose = 0;
38
39sub reply_handler {
40    my ($qname, $qclass, $qtype, $peerhost, $query, $conn) = @_;
41    my ($rcode, @ans, @auth, @add);
42
43    print ("request: $qname/$qtype\n");
44    STDOUT->flush();
45
46    $count += 1;
47
48    if ($qname eq "count" ) {
49        if ($qtype eq "TXT") {
50            my ($ttl, $rdata) = (0, "$count");
51            my $rr = new Net::DNS::RR("$qname $ttl $qclass $qtype $rdata");
52            push @ans, $rr;
53            print ("\tcount: $count\n");
54        }
55        $rcode = "NOERROR";
56    } elsif ($qname eq "reset" ) {
57        $count = 0;
58        $send_response = 0;
59        $rcode = "NOERROR";
60    } elsif ($qname eq "direct.example.net" ) {
61        if ($qtype eq "A") {
62            my ($ttl, $rdata) = (3600, $localaddr);
63            my $rr = new Net::DNS::RR("$qname $ttl $qclass $qtype $rdata");
64            push @ans, $rr;
65        }
66        $rcode = "NOERROR";
67    } elsif( $qname =~ /^ns1\.(\d+)\.example\.net$/ ) {
68        my $next = ($1 + 1) * 16;
69        for (my $i = 1; $i < 16; $i++) {
70            my $s = $next + $i;
71            my $rr = new Net::DNS::RR("$1.example.net 86400 $qclass NS ns1.$s.example.net");
72            push @auth, $rr;
73            $rr = new Net::DNS::RR("ns1.$s.example.net 86400 $qclass A 10.53.0.7");
74            push @add, $rr;
75        }
76        $rcode = "NOERROR";
77    } else {
78        $rcode = "NXDOMAIN";
79    }
80
81    # mark the answer as authoritive (by setting the 'aa' flag
82    return ($rcode, \@ans, \@auth, \@add, { aa => 1 });
83}
84
85GetOptions(
86    'port=i' => \$localport,
87    'verbose!' => \$verbose,
88);
89
90my $ns = Net::DNS::Nameserver->new(
91    LocalAddr => $localaddr,
92    LocalPort => $localport,
93    ReplyHandler => \&reply_handler,
94    Verbose => $verbose,
95);
96
97$ns->main_loop;
98