#!/usr/bin/perl -w # 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. # # Don't respond if the "norespond" file exists; otherwise respond to # any A or AAAA query. # use IO::File; use IO::Socket; use Net::DNS; use Net::DNS::Packet; my $localport = int($ENV{'PORT'}); if (!$localport) { $localport = 5300; } my $sock = IO::Socket::INET->new(LocalAddr => "10.53.0.4", LocalPort => $localport, Proto => "udp") or die "$!"; 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 (-e 'norespond') { $donotrespond = 1; } else { $packet->header->aa(1); if ($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")); } } if ($donotrespond == 0) { $sock->send($packet->data); print "RESPONSE:\n"; $packet->print; print "\n"; } }