1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
|
#!/usr/bin/perl
#
# Copyright (C) 2004, 2007 Internet Systems Consortium, Inc. ("ISC")
# Copyright (C) 2001 Internet Software Consortium.
#
# 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: ans.pl,v 1.6 2007/09/24 04:13:25 marka Exp $
#
# This is the name server from hell. It provides canned
# responses based on pattern matching the queries, and
# can be reprogrammed on-the-fly over a TCP connection.
#
# The server listens for control connections on port 5301.
# A control connection is a TCP stream of lines like
#
# /pattern/
# name ttl type rdata
# name ttl type rdata
# ...
# /pattern/
# name ttl type rdata
# name ttl type rdata
# ...
#
# There can be any number of patterns, each associated
# with any number of response RRs. Each pattern is a
# Perl regular expression.
#
# Each incoming query is converted into a string of the form
# "qname qtype" (the printable query domain name, space,
# printable query type) and matched against each pattern.
#
# The first pattern matching the query is selected, and
# the RR following the pattern line are sent in the
# answer section of the response.
#
# Each new control connection causes the current set of
# patterns and responses to be cleared before adding new
# ones.
#
# The server handles UDP and TCP queries. Zone transfer
# responses work, but must fit in a single 64 k message.
#
use IO::File;
use IO::Socket;
use Net::DNS;
use Net::DNS::Packet;
my $ctlsock = IO::Socket::INET->new(LocalAddr => "10.53.0.2",
LocalPort => 5301, Proto => "tcp", Listen => 5, Reuse => 1) or die "$!";
my $udpsock = IO::Socket::INET->new(LocalAddr => "10.53.0.2",
LocalPort => 5300, Proto => "udp", Reuse => 1) or die "$!";
my $tcpsock = IO::Socket::INET->new(LocalAddr => "10.53.0.2",
LocalPort => 5300, Proto => "tcp", Listen => 5, Reuse => 1) or die "$!";
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;
$SIG{TERM} = \&rmpid;
my @answers = ();
sub handle {
my ($buf) = @_;
my ($packet, $err) = new Net::DNS::Packet(\$buf, 0);
$err and die $err;
$packet->header->qr(1);
$packet->header->aa(1);
my @questions = $packet->question;
my $qname = $questions[0]->qname;
my $qtype = $questions[0]->qtype;
my $r;
foreach $r (@rules) {
my $pattern = $r->{pattern};
warn "match $qname $qtype == $pattern";
if ("$qname $qtype" =~ /$pattern/) {
my $a;
foreach $a (@{$r->{answer}}) {
$packet->push("answer", $a);
}
last;
}
}
# $packet->print;
return $packet->data;
}
for (;;) {
$rin = '';
vec($rin, fileno($ctlsock), 1) = 1;
vec($rin, fileno($tcpsock), 1) = 1;
vec($rin, fileno($udpsock), 1) = 1;
select($rout = $rin, undef, undef, undef);
if (vec($rout, fileno($ctlsock), 1)) {
warn "ctl conn";
my $conn = $ctlsock->accept;
@rules = ();
while (my $line = $conn->getline) {
chomp $line;
if ($line =~ m!^/(.*)/$!) {
$rule = { pattern => $1, answer => [] };
push(@rules, $rule);
} else {
push(@{$rule->{answer}},
new Net::DNS::RR($line));
}
}
$conn->close;
} elsif (vec($rout, fileno($udpsock), 1)) {
printf "UDP request\n";
$udpsock->recv($buf, 512);
$response = handle($buf);
$udpsock->send($response);
} elsif (vec($rout, fileno($tcpsock), 1)) {
my $conn = $tcpsock->accept;
for (;;) {
printf "TCP request\n";
my $n = $conn->sysread($lenbuf, 2);
last unless $n == 2;
my $len = unpack("n", $lenbuf);
$n = $conn->sysread($buf, $len);
last unless $n == $len;
$response = handle($buf);
$len = length($response);
$n = $conn->syswrite(pack("n", $len), 2);
$n = $conn->syswrite($response, $len);
}
$conn->close;
}
}
|
