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#!/usr/bin/env perl
# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
#
# SPDX-License-Identifier: MPL-2.0
#
# 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 https://mozilla.org/MPL/2.0/.
#
# See the COPYRIGHT file distributed with this work for additional
# information regarding copyright ownership.
use strict;
use warnings;
use IO::File;
use IO::Socket;
use Getopt::Long;
use Net::DNS;
use Time::HiRes qw(usleep nanosleep);
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;
# If send_response is set, the server will respond, otherwise the query will
# be dropped.
my $send_response = 1;
# If slow_response is set, a lookup for the CNAME target (target.example) is
# delayed. Other lookups will not be delayed.
my $slow_response = 0;
my $localaddr = "10.53.0.2";
my $localport = int($ENV{'PORT'});
if (!$localport) { $localport = 5300; }
my $udpsock = IO::Socket::INET->new(LocalAddr => "$localaddr",
LocalPort => $localport, Proto => "udp", Reuse => 1) or die "$!";
#
# Delegation
#
my $SOA = "example 300 IN SOA . . 0 0 0 0 300";
my $NS = "example 300 IN NS ns.example";
my $A = "ns.example 300 IN A $localaddr";
#
# Slow delegation
#
my $slowSOA = "slow 300 IN SOA . . 0 0 0 0 300";
my $slowNS = "slow 300 IN NS ns.slow";
my $slowA = "ns.slow 300 IN A $localaddr";
my $slowTXT = "data.slow 2 IN TXT \"A slow text record with a 2 second ttl\"";
my $slownegSOA = "slow 2 IN SOA . . 0 0 0 0 300";
#
# Records to be TTL stretched
#
my $TXT = "data.example 2 IN TXT \"A text record with a 2 second ttl\"";
my $LONGTXT = "longttl.example 600 IN TXT \"A text record with a 600 second ttl\"";
my $CAA = "othertype.example 2 IN CAA 0 issue \"ca1.example.net\"";
my $negSOA = "example 2 IN SOA . . 0 0 0 0 300";
my $CNAME = "cname.example 7 IN CNAME target.example";
my $TARGET = "target.example 9 IN A $localaddr";
my $SHORTCNAME = "shortttl.cname.example 1 IN CNAME longttl.target.example";
my $LONGTARGET = "longttl.target.example 600 IN A $localaddr";
sub reply_handler {
my ($qname, $qclass, $qtype) = @_;
my ($rcode, @ans, @auth, @add);
print ("request: $qname/$qtype\n");
STDOUT->flush();
# Control whether we send a response or not.
# We always respond to control commands.
if ($qname eq "enable" ) {
if ($qtype eq "TXT") {
$send_response = 1;
my $rr = new Net::DNS::RR("$qname 0 $qclass TXT \"$send_response\"");
push @ans, $rr;
}
$rcode = "NOERROR";
return ($rcode, \@ans, \@auth, \@add, { aa => 1 });
} elsif ($qname eq "disable" ) {
if ($qtype eq "TXT") {
$send_response = 0;
my $rr = new Net::DNS::RR("$qname 0 $qclass TXT \"$send_response\"");
push @ans, $rr;
}
$rcode = "NOERROR";
return ($rcode, \@ans, \@auth, \@add, { aa => 1 });
} elsif ($qname eq "slowdown" ) {
if ($qtype eq "TXT") {
$send_response = 1;
$slow_response = 1;
my $rr = new Net::DNS::RR("$qname 0 $qclass TXT \"$send_response\"");
push @ans, $rr;
}
$rcode = "NOERROR";
return ($rcode, \@ans, \@auth, \@add, { aa => 1 });
}
# If we are not responding to queries we are done.
return if (!$send_response);
if (index($qname, "latency") == 0) {
# simulate network latency before answering
print " Sleeping 50 milliseconds\n";
select(undef, undef, undef, 0.05);
}
# Construct the response and send it.
if ($qname eq "ns.example" ) {
if ($qtype eq "A") {
my $rr = new Net::DNS::RR($A);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($SOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "example") {
if ($qtype eq "NS") {
my $rr = new Net::DNS::RR($NS);
push @auth, $rr;
$rr = new Net::DNS::RR($A);
push @add, $rr;
} elsif ($qtype eq "SOA") {
my $rr = new Net::DNS::RR($SOA);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($SOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "nodata.example") {
my $rr = new Net::DNS::RR($negSOA);
push @auth, $rr;
$rcode = "NOERROR";
} elsif ($qname eq "data.example") {
if ($qtype eq "TXT") {
my $rr = new Net::DNS::RR($TXT);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($negSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "a-only.example") {
if ($qtype eq "A") {
my $rr = new Net::DNS::RR("a-only.example 2 IN A $localaddr");
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($negSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "cname.example") {
if ($qtype eq "A") {
my $rr = new Net::DNS::RR($CNAME);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($negSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "target.example") {
if ($slow_response) {
print " Sleeping 3 seconds\n";
sleep(3);
}
if ($qtype eq "A") {
my $rr = new Net::DNS::RR($TARGET);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($negSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "shortttl.cname.example") {
if ($qtype eq "A") {
my $rr = new Net::DNS::RR($SHORTCNAME);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($negSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "longttl.target.example") {
if ($slow_response) {
print " Sleeping 3 seconds\n";
sleep(3);
}
if ($qtype eq "A") {
my $rr = new Net::DNS::RR($LONGTARGET);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($negSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "longttl.example") {
if ($qtype eq "TXT") {
my $rr = new Net::DNS::RR($LONGTXT);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($negSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "nxdomain.example") {
my $rr = new Net::DNS::RR($negSOA);
push @auth, $rr;
$rcode = "NXDOMAIN";
} elsif ($qname eq "othertype.example") {
if ($qtype eq "CAA") {
my $rr = new Net::DNS::RR($CAA);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($negSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "ns.slow" ) {
if ($qtype eq "A") {
my $rr = new Net::DNS::RR($slowA);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($slowSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "slow") {
if ($qtype eq "NS") {
my $rr = new Net::DNS::RR($slowNS);
push @auth, $rr;
$rr = new Net::DNS::RR($slowA);
push @add, $rr;
} elsif ($qtype eq "SOA") {
my $rr = new Net::DNS::RR($slowSOA);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($slowSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "data.slow") {
if ($slow_response) {
print " Sleeping 3 seconds\n";
sleep(3);
# only one time
$slow_response = 0;
}
if ($qtype eq "TXT") {
my $rr = new Net::DNS::RR($slowTXT);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($slownegSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} else {
my $rr = new Net::DNS::RR($SOA);
push @auth, $rr;
$rcode = "NXDOMAIN";
}
# mark the answer as authoritative (by setting the 'aa' flag)
return ($rcode, \@ans, \@auth, \@add, { aa => 1 });
}
GetOptions(
'port=i' => \$localport,
);
my $rin;
my $rout;
for (;;) {
$rin = '';
vec($rin, fileno($udpsock), 1) = 1;
select($rout = $rin, undef, undef, undef);
if (vec($rout, fileno($udpsock), 1)) {
my ($buf, $request, $err);
$udpsock->recv($buf, 512);
if ($Net::DNS::VERSION > 0.68) {
$request = new Net::DNS::Packet(\$buf, 0);
$@ and die $@;
} else {
my $err;
($request, $err) = new Net::DNS::Packet(\$buf, 0);
$err and die $err;
}
my @questions = $request->question;
my $qname = $questions[0]->qname;
my $qclass = $questions[0]->qclass;
my $qtype = $questions[0]->qtype;
my $id = $request->header->id;
my ($rcode, $ans, $auth, $add, $headermask) = reply_handler($qname, $qclass, $qtype);
if (!defined($rcode)) {
print " Silently ignoring query\n";
next;
}
my $reply = Net::DNS::Packet->new();
$reply->header->qr(1);
$reply->header->aa(1) if $headermask->{'aa'};
$reply->header->id($id);
$reply->header->rcode($rcode);
$reply->push("question", @questions);
$reply->push("answer", @$ans) if $ans;
$reply->push("authority", @$auth) if $auth;
$reply->push("additional", @$add) if $add;
my $num_chars = $udpsock->send($reply->data);
print " Sent $num_chars bytes via UDP\n";
}
}
|
