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|
# -*- perl -*-
#
# INetSim::DNS - A fake DNS server
#
# RFC 1035 (and many others) - Domain Name System
#
# (c)2007-2019 Matthias Eckert, Thomas Hungenberg
#
#############################################################
package INetSim::DNS;
use strict;
use warnings;
use Net::DNS;
use Net::DNS::Nameserver;
sub dns{
# check for broken version 0.65 of Net::DNS
if ($Net::DNS::VERSION eq "0.65") {
INetSim::Log::MainLog("failed! (The installed version 0.65 of Perl library Net::DNS is broken. Please upgrade to version 0.66 or later.)", INetSim::Config::getConfigParameter("DNS_ServiceName"));
exit 1;
}
my $CPID = $$;
my $localaddr = (defined INetSim::Config::getConfigParameter("DNS_BindAddress") ? INetSim::Config::getConfigParameter("DNS_BindAddress") : INetSim::Config::getConfigParameter("Default_BindAddress"));
$localaddr =~ /\A(.*)\z/; # fool taint check
$localaddr = $1;
my $bindport = INetSim::Config::getConfigParameter("DNS_BindPort");
$bindport =~ /\A(.*)\z/; # fool taint check
$bindport = $1;
local $SIG{'INT'} = 'IGNORE';
local $SIG{'TERM'} = sub {INetSim::Log::MainLog("stopped (PID $CPID)", INetSim::Config::getConfigParameter("DNS_ServiceName")); exit 0;};
my $server = Net::DNS::Nameserver->new(LocalAddr => $localaddr,
LocalPort => $bindport,
ReplyHandler => \&dns_reply_handler,
Verbose => '0');
if(! $server) {
INetSim::Log::MainLog("failed!", INetSim::Config::getConfigParameter("DNS_ServiceName"));
exit 1;
}
# drop root privileges
my $runasuser = INetSim::Config::getConfigParameter("Default_RunAsUser");
my $runasgroup = INetSim::Config::getConfigParameter("Default_RunAsGroup");
my $uid = getpwnam($runasuser);
my $gid = getgrnam($runasgroup);
POSIX::setgid($gid);
my $newgid = POSIX::getgid();
if ($newgid != $gid) {
INetSim::Log::MainLog("failed! (Cannot switch group)", INetSim::Config::getConfigParameter("DNS_ServiceName"));
exit 0;
}
POSIX::setuid($uid);
if ($< != $uid || $> != $uid) {
$< = $> = $uid; # try again - reportedly needed by some Perl 5.8.0 Linux systems
if ($< != $uid) {
INetSim::Log::MainLog("failed! (Cannot switch user)", INetSim::Config::getConfigParameter("DNS_ServiceName"));
exit 0;
}
}
$0 = 'inetsim_' . INetSim::Config::getConfigParameter("DNS_ServiceName");
INetSim::Log::MainLog("started (PID $CPID)", INetSim::Config::getConfigParameter("DNS_ServiceName"));
$server->main_loop;
INetSim::Log::MainLog("stopped (PID $CPID)", INetSim::Config::getConfigParameter("DNS_ServiceName"));
exit 0;
}
sub dns_reply_handler {
# STILL NEEDS WORK !!!
my ($queryname, $queryclass, $querytype, $rhost, $query) = @_;
my (@ans, @auth, @add) = ();
my @logans = ();
my $resultcode = "REFUSED";
my $ttl = 3600;
my $SOA_serial = 20150801;
my $SOA_refresh = 1000;
my $SOA_retry = 800;
my $SOA_expire = 7200;
my $SOA_minimum = 3600;
my $stat_success = 0;
my $serviceName = INetSim::Config::getConfigParameter("DNS_ServiceName");
my $localaddress = INetSim::Config::getConfigParameter("Default_BindAddress");
INetSim::Log::SubLog("[$rhost] connect", $serviceName, $$);
if (! defined ($queryname) || ! defined ($queryclass) || ! defined ($querytype) || ! defined ($rhost)) {
$resultcode = "SERVFAIL";
}
elsif (($queryclass ne "IN") && ($queryclass ne "CH")) {
$resultcode = "REFUSED";
}
elsif (length($queryname) > 255) {
$resultcode = "FORMERR";
}
elsif ($querytype eq "A") {
my $rdata;
if ($queryname =~ /\Awpad\z/i || $queryname =~ /\Awpad\..*/i) {
$rdata = $localaddress;
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass A $rdata");
push (@logans, "$queryname $ttl $queryclass A $rdata");
$resultcode = "NOERROR";
}
else {
if ($queryname =~ /\A[0-9a-zA-Z-.]{1,255}\z/) {
$rdata = &getIP($queryname);
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass A $rdata");
push (@logans, "$queryname $ttl $queryclass A $rdata");
$resultcode = "NOERROR";
}
else {
# invalid queryname
$resultcode = "NXDOMAIN";
}
}
}
elsif ($querytype eq "SOA") {
if ($queryname =~ /\A[0-9a-zA-Z-.]{1,255}\z/) {
# Answer section
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass SOA ns1.$queryname hostmaster.$queryname $SOA_serial $SOA_refresh $SOA_retry $SOA_expire $SOA_minimum");
push @logans, "$queryname $ttl $queryclass SOA ns1.$queryname hostmaster.$queryname $SOA_serial $SOA_refresh $SOA_retry $SOA_expire $SOA_minimum";
# NS in Authority section
push @auth, Net::DNS::RR->new("$queryname $ttl $queryclass NS ns1.$queryname");
push @auth, Net::DNS::RR->new("$queryname $ttl $queryclass NS ns2.$queryname");
push @logans, "$queryname $ttl $queryclass NS ns1.$queryname";
push @logans, "$queryname $ttl $queryclass NS ns2.$queryname";
# IPs for NS NS in Additional section
my $ns1ip = getIP("ns1.$queryname");
my $ns2ip = getIP("ns2.$queryname");
push @add, Net::DNS::RR->new("ns1.$queryname $ttl $queryclass A $ns1ip");
push @add, Net::DNS::RR->new("ns2.$queryname $ttl $queryclass A $ns2ip");
push @logans, "ns1.$queryname $ttl $queryclass A $ns1ip";
push @logans, "ns2.$queryname $ttl $queryclass A $ns2ip";
$resultcode = "NOERROR";
}
else {
# invalid queryname
$resultcode = "NXDOMAIN";
}
}
elsif ($querytype eq "PTR") {
if ($queryname =~ /\A[0-9a-zA-Z-.]{1,255}\z/) {
my $rdata = &getHost($queryname);
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass PTR $rdata");
push @logans, "$queryname $ttl $queryclass $querytype $rdata";
$resultcode = "NOERROR";
}
else {
# invalid queryname
$resultcode = "NXDOMAIN";
}
}
elsif ($querytype eq "TXT") {
my $rdata;
# http://www.ietf.org/rfc/rfc4892.txt
# http://www.ietf.org/proceedings/54/I-D/draft-ietf-dnsop-serverid-00.txt
if ($queryclass eq "CH" && ($queryname =~ /\A(version|hostname)\.bind/i || $queryname =~ /\A(id|version)\.server/i)) {
$rdata = INetSim::Config::getConfigParameter("DNS_Version");
}
elsif ($queryname =~ /\A[0-9a-zA-Z-.]{1,255}\z/) {
$rdata = "this is a txt record";
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass TXT \"$rdata\"");
push @logans, "$queryname $ttl $queryclass $querytype \"$rdata\"";
$resultcode = "NOERROR";
}
else {
# invalid queryname
$resultcode = "NXDOMAIN";
}
}
elsif ($querytype eq "MX") {
if ($queryname =~ /\A[0-9a-zA-Z-.]{1,255}\z/) {
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass MX 10 mx1.$queryname");
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass MX 20 mx2.$queryname");
push (@logans, "$queryname $ttl $queryclass MX 10 mx1.$queryname");
push (@logans, "$queryname $ttl $queryclass MX 20 mx2.$queryname");
# IP-Adressen fr MX in Additional Section
my $mx1ip = getIP("mx1.$queryname");
my $mx2ip = getIP("mx2.$queryname");
push @add, Net::DNS::RR->new("mx1.$queryname $ttl $queryclass A $mx1ip");
push @add, Net::DNS::RR->new("mx2.$queryname $ttl $queryclass A $mx2ip");
push (@logans, "mx1.$queryname $ttl $queryclass A $mx1ip");
push (@logans, "mx2.$queryname $ttl $queryclass A $mx2ip");
$resultcode = "NOERROR";
}
else {
# invalid queryname
$resultcode = "NXDOMAIN";
}
}
elsif ($querytype eq "NS") {
if ($queryname =~ /\A[0-9a-zA-Z-.]{1,255}\z/) {
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass NS ns1.$queryname");
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass NS ns2.$queryname");
push (@logans, "$queryname $ttl $queryclass NS ns1.$queryname");
push (@logans, "$queryname $ttl $queryclass NS ns2.$queryname");
# IPs for NS in Additional Section
my $ns1ip = getIP("ns1.$queryname");
my $ns2ip = getIP("ns2.$queryname");
push @add, Net::DNS::RR->new("ns1.$queryname $ttl $queryclass A $ns1ip");
push @add, Net::DNS::RR->new("ns2.$queryname $ttl $queryclass A $ns2ip");
push @logans, "ns1.$queryname $ttl $queryclass A $ns1ip";
push @logans, "ns2.$queryname $ttl $queryclass A $ns2ip";
$resultcode = "NOERROR";
}
else {
# invalid queryname
$resultcode = "NXDOMAIN";
}
}
elsif ($querytype eq "ANY") {
if ($queryname =~ /\A[0-9a-zA-Z-.]{1,255}\z/) {
# SOA
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass SOA ns1.$queryname hostmaster.$queryname $SOA_serial $SOA_refresh $SOA_retry $SOA_expire $SOA_minimum");
push @logans, "$queryname $ttl $queryclass SOA ns1.$queryname hostmaster.$queryname $SOA_serial $SOA_refresh $SOA_retry $SOA_expire $SOA_minimum";
# NS
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass NS ns1.$queryname");
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass NS ns2.$queryname");
push (@logans, "$queryname $ttl $queryclass NS ns1.$queryname");
push (@logans, "$queryname $ttl $queryclass NS ns2.$queryname");
# MX
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass MX 10 mx1.$queryname");
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass MX 20 mx2.$queryname");
push (@logans, "$queryname $ttl $queryclass $querytype 10 mx1.$queryname");
push (@logans, "$queryname $ttl $queryclass $querytype 20 mx2.$queryname");
# A
my $rdata = &getIP($queryname);
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass A $rdata");
push (@logans, "$queryname $ttl $queryclass A $rdata");
# IPs for NS and MX
my $ns1ip = getIP("ns1.$queryname");
my $ns2ip = getIP("ns2.$queryname");
push @add, Net::DNS::RR->new("ns1.$queryname $ttl $queryclass A $ns1ip");
push @add, Net::DNS::RR->new("ns2.$queryname $ttl $queryclass A $ns2ip");
push @logans, "ns1.$queryname $ttl $queryclass A $ns1ip";
push @logans, "ns2.$queryname $ttl $queryclass A $ns2ip";
my $mx1ip = getIP("mx1.$queryname");
my $mx2ip = getIP("mx2.$queryname");
push @add, Net::DNS::RR->new("mx1.$queryname $ttl $queryclass A $mx1ip");
push @add, Net::DNS::RR->new("mx2.$queryname $ttl $queryclass A $mx2ip");
push (@logans, "mx1.$queryname $ttl $queryclass A $mx1ip");
push (@logans, "mx2.$queryname $ttl $queryclass A $mx2ip");
$resultcode = "NOERROR";
}
else {
# invalid queryname
$resultcode = "NXDOMAIN";
}
}
elsif ($querytype eq "CNAME") {
if ($queryname =~ /\A[0-9a-zA-Z-.]{1,255}\z/) {
# some host
push @ans, Net::DNS::RR->new("$queryname $ttl $queryclass CNAME host.$queryname");
push (@logans, "$queryname $ttl $queryclass CNAME host.$queryname");
$resultcode = "NOERROR";
}
else {
# invalid queryname
$resultcode = "NXDOMAIN";
}
}
elsif ($querytype eq "AXFR") {
$resultcode = "REFUSED";
}
elsif ($querytype eq "AAAA") {
$resultcode = "NOERROR";
}
else {
# $resultcode = "NXDOMAIN";
$resultcode = "NOTIMP";
}
INetSim::Log::SubLog("[$rhost] recv: Query Type ".$querytype.", Class ".$queryclass.", Name ".$queryname, $serviceName, $$);
if ($resultcode ne "NXDOMAIN" && $resultcode ne "REFUSED" && $resultcode ne "NOTIMP" && $resultcode ne "SERVFAIL") {
foreach my $msg (@logans){
INetSim::Log::SubLog("[$rhost] send: ".$msg, $serviceName, $$);
}
$stat_success = 1;
}
else {
INetSim::Log::SubLog("[$rhost] Error: $resultcode", $serviceName, $$);
}
INetSim::Log::SubLog("[$rhost] disconnect", $serviceName, $$);
INetSim::Log::SubLog("[$rhost] stat: $stat_success qtype=$querytype qclass=$queryclass qname=$queryname", $serviceName, $$);
return ($resultcode, \@ans, \@auth, \@add, {aa => 1});
}
sub getIP {
my $hostname = lc(shift);
my %static_host_to_ip = INetSim::Config::getConfigHash("DNS_StaticHostToIP");
if (defined $static_host_to_ip{$hostname}) {
return $static_host_to_ip{$hostname};
}
else {
return INetSim::Config::getConfigParameter("DNS_Default_IP");
}
}
sub getHost {
my $ip = lc(shift);
my %static_ip_to_host = INetSim::Config::getConfigHash("DNS_StaticIPToHost");
if (defined $static_ip_to_host{$ip}) {
return $static_ip_to_host{$ip};
}
else {
return INetSim::Config::getConfigParameter("DNS_Default_Hostname") . "." . INetSim::Config::getConfigParameter("DNS_Default_Domainname");
}
}
1;
#
|
