mail_resolver.t - nginx-tests - Git at Google

 #!/usr/bin/perl

 # (C) Sergey Kandaurov
 # (C) Nginx, Inc.

 # Tests for mail resolver.

 ###############################################################################

 use warnings;
 use strict;

 use Test::More;

 BEGIN { use FindBin; chdir($FindBin::Bin); }

 use lib 'lib';
 use Test::Nginx;
 use Test::Nginx::SMTP;

 ###############################################################################

 select STDERR; $| = 1;
 select STDOUT; $| = 1;

 eval { require IO::Socket::SSL; };
 plan(skip_all => 'IO::Socket::SSL not installed') if $@;
 eval { IO::Socket::SSL::SSL_VERIFY_NONE(); };
 plan(skip_all => 'IO::Socket::SSL too old') if $@;

 local $SIG{PIPE} = 'IGNORE';

 my $t = Test::Nginx->new()->has(qw/mail mail_ssl smtp http rewrite/)
 	->has_daemon('openssl')->plan(11)
 	->write_file_expand('nginx.conf', <<'EOF');

 %%TEST_GLOBALS%%

 daemon off;

 events {
 }

 mail {
     auth_http    http://127.0.0.1:8080/mail/auth;
     smtp_auth    none;
     server_name  locahost;

     proxy_timeout 15s;

     # prevent useless resend
     resolver_timeout 2s;

     server {
         listen    127.0.0.1:8025;
         protocol  smtp;
         resolver  127.0.0.1:%%PORT_8981_UDP%%
                   127.0.0.1:%%PORT_8982_UDP%%
                   127.0.0.1:%%PORT_8983_UDP%%;
     }

     server {
         listen    127.0.0.1:8027;
         protocol  smtp;
         resolver  127.0.0.1:%%PORT_8982_UDP%%;
     }

     server {
         listen    127.0.0.1:8028;
         protocol  smtp;
         resolver  127.0.0.1:%%PORT_8983_UDP%%;
         resolver_timeout 1s;
     }

     server {
         listen    127.0.0.1:8029;
         protocol  smtp;
         resolver  127.0.0.1:%%PORT_8984_UDP%%;
     }

     server {
         listen    127.0.0.1:8030;
         protocol  smtp;
         resolver  127.0.0.1:%%PORT_8985_UDP%%;
     }

     server {
         listen    127.0.0.1:8031;
         protocol  smtp;
         resolver  127.0.0.1:%%PORT_8986_UDP%%;
         resolver_timeout 1s;
     }

     server {
         listen    127.0.0.1:8032;
         protocol  smtp;
         resolver  127.0.0.1:%%PORT_8987_UDP%%;
     }

     server {
         ssl_certificate_key localhost.key;
         ssl_certificate localhost.crt;

         listen    127.0.0.1:8033 ssl;
         protocol  smtp;
         resolver  127.0.0.1:%%PORT_8983_UDP%%;
     }
 }

 http {
     %%TEST_GLOBALS_HTTP%%

     server {
         listen       127.0.0.1:8080;
         server_name  localhost;

         location = /mail/auth {
             set $reply $http_client_host;

             if ($http_client_host !~ UNAVAIL) {
                 set $reply OK;
             }

             add_header Auth-Status $reply;
             add_header Auth-Server 127.0.0.1;
             add_header Auth-Port %%PORT_8026%%;
             return 204;
         }
     }
 }

 EOF

 $t->write_file('openssl.conf', <<EOF);
 [ req ]
 default_bits = 2048
 encrypt_key = no
 distinguished_name = req_distinguished_name
 [ req_distinguished_name ]
 EOF

 my $d = $t->testdir();

 foreach my $name ('localhost') {
 	system('openssl req -x509 -new '
 		. "-config $d/openssl.conf -subj /CN=$name/ "
 		. "-out $d/$name.crt -keyout $d/$name.key "
 		. ">>$d/openssl.out 2>&1") == 0
 		or die "Can't create certificate for $name: $!\n";
 }

 $t->run_daemon(\&Test::Nginx::SMTP::smtp_test_daemon);
 $t->run_daemon(\&dns_daemon, port($_), $t) foreach (8981 .. 8987);

 $t->run();

 $t->waitforsocket('127.0.0.1:' . port(8026));
 $t->waitforfile($t->testdir . '/' . port($_)) foreach (8981 .. 8987);

 ###############################################################################

 # PTR

 my $s = Test::Nginx::SMTP->new();
 my $s2 = Test::Nginx::SMTP->new();
 $s->read();
 $s->send('EHLO example.com');
 $s->read();
 $s->send('MAIL FROM:<test@example.com> SIZE=100');
 $s->read();

 $s->send('RCPT TO:<test@example.com>');
 $s->ok('PTR');

 $s->send('QUIT');
 $s->read();

 $s2->read();
 $s2->send('EHLO example.com');
 $s2->ok('PTR waiting');

 # Cached PTR prevents from querying bad ns on port 8983

 $s = Test::Nginx::SMTP->new();
 $s->read();
 $s->send('EHLO example.com');
 $s->read();
 $s->send('MAIL FROM:<test@example.com> SIZE=100');
 $s->read();

 $s->send('RCPT TO:<test@example.com>');
 $s->ok('PTR cached');

 $s->send('QUIT');
 $s->read();

 # SERVFAIL

 $s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8027));
 $s->read();
 $s->send('EHLO example.com');
 $s->read();
 $s->send('MAIL FROM:<test@example.com> SIZE=100');
 $s->read();

 $s->send('RCPT TO:<test@example.com>');
 $s->check(qr/TEMPUNAVAIL/, 'PTR SERVFAIL');

 $s->send('QUIT');
 $s->read();

 # PTR with zero length RDATA

 $s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8028));
 $s2 = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8028));
 $s->read();
 $s->send('EHLO example.com');
 $s->read();
 $s->send('MAIL FROM:<test@example.com> SIZE=100');
 $s->read();

 $s->send('RCPT TO:<test@example.com>');
 $s->check(qr/TEMPUNAVAIL/, 'PTR empty');

 $s->send('QUIT');
 $s->read();

 # resolver timeout is set

 $s2->read();
 $s2->send('EHLO example.com');
 $s2->ok('PTR empty waiting');

 # CNAME

 TODO: {
 local $TODO = 'support for CNAME RR';

 $s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8029));
 $s->read();
 $s->send('EHLO example.com');
 $s->read();
 $s->send('MAIL FROM:<test@example.com> SIZE=100');
 $s->read();

 $s->send('RCPT TO:<test@example.com>');
 $s->ok('CNAME');

 $s->send('QUIT');
 $s->read();

 }

 # uncompressed answer

 $s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8030));
 $s->read();
 $s->send('EHLO example.com');
 $s->read();
 $s->send('MAIL FROM:<test@example.com> SIZE=100');
 $s->read();

 $s->send('RCPT TO:<test@example.com>');
 $s->ok('uncompressed PTR');

 $s->send('QUIT');
 $s->read();

 $s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8031));
 $s->read();
 $s->send('EHLO example.com');
 $s->read();
 $s->send('MAIL FROM:<test@example.com> SIZE=100');
 $s->read();

 $s->send('RCPT TO:<test@example.com>');
 $s->check(qr/TEMPUNAVAIL/, 'PTR type');

 $s->send('QUIT');
 $s->read();

 # CNAME and PTR in one answer section

 $s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8032));
 $s->read();
 $s->send('EHLO example.com');
 $s->read();
 $s->send('MAIL FROM:<test@example.com> SIZE=100');
 $s->read();

 $s->send('RCPT TO:<test@example.com>');
 $s->ok('CNAME with PTR');

 $s->send('QUIT');
 $s->read();

 # before 1.17.3, read event while in resolving resulted in duplicate resolving

 TODO: {
 todo_skip 'leaves coredump', 1 unless $ENV{TEST_NGINX_UNSAFE}
 	or $t->has_version('1.17.3');

 my %ssl = (
 	SSL => 1,
 	SSL_verify_mode => IO::Socket::SSL::SSL_VERIFY_NONE(),
 	SSL_error_trap => sub { die $_[1] },
 );

 $s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8033), %ssl);
 $s->send('EHLO example.com');
 $s->read();
 $s->send('MAIL FROM:<test@example.com> SIZE=100');
 $s->read();
 $s->read();

 $s->send('RCPT TO:<test@example.com>');
 $s->check(qr/TEMPUNAVAIL/, 'PTR SSL empty');

 $s->send('QUIT');
 $s->read();

 }

 ###############################################################################

 sub reply_handler {
 	my ($recv_data, $port) = @_;

 	my (@name, @rdata);

 	use constant NOERROR	=> 0;
 	use constant SERVFAIL	=> 2;
 	use constant NXDOMAIN	=> 3;

 	use constant A		=> 1;
 	use constant CNAME	=> 5;
 	use constant PTR	=> 12;
 	use constant DNAME	=> 39;

 	use constant IN		=> 1;

 	# default values

 	my ($hdr, $rcode, $ttl) = (0x8180, NOERROR, 3600);

 	# decode name

 	my ($len, $offset) = (undef, 12);
 	while (1) {
 		$len = unpack("\@$offset C", $recv_data);
 		last if $len == 0;
 		$offset++;
 		push @name, unpack("\@$offset A$len", $recv_data);
 		$offset += $len;
 	}

 	$offset -= 1;
 	my ($id, $type, $class) = unpack("n x$offset n2", $recv_data);

 	my $name = join('.', @name);
 	if ($name eq 'a.example.net' && $type == A) {
 		push @rdata, rd_addr($ttl, '127.0.0.1');

 	} elsif ($name eq '1.0.0.127.in-addr.arpa' && $type == PTR) {
 		if ($port == port(8981)) {
 			push @rdata, rd_name(PTR, $ttl, 'a.example.net');

 		} elsif ($port == port(8982)) {
 			$rcode = SERVFAIL;

 		} elsif ($port == port(8983)) {
 			# zero length RDATA

 			push @rdata, pack("n3N n", 0xc00c, PTR, IN, $ttl, 0);

 		} elsif ($port == port(8984)) {
 			# PTR answered with CNAME

 			push @rdata, rd_name(CNAME, $ttl,
 				'1.1.0.0.127.in-addr.arpa');

 		} elsif ($port == port(8985)) {
 			# uncompressed answer

 			push @rdata, pack("(C/a*)6x n2N n(C/a*)3x",
 				('1', '0', '0', '127', 'in-addr', 'arpa'),
 				PTR, IN, $ttl, 15, ('a', 'example', 'net'));

 		} elsif ($port == port(8986)) {
 			push @rdata, rd_name(DNAME, $ttl, 'a.example.net');

 		} elsif ($port == port(8987)) {
 			# PTR answered with CNAME+PTR

 			push @rdata, rd_name(CNAME, $ttl,
 				'1.1.0.0.127.in-addr.arpa');
 			push @rdata, pack("n3N n(C/a*)3 x", 0xc034,
 				PTR, IN, $ttl, 15, ('a', 'example', 'net'));
 		}

 	} elsif ($name eq '1.1.0.0.127.in-addr.arpa' && $type == PTR) {
 		push @rdata, rd_name(PTR, $ttl, 'a.example.net');
 	}

 	$len = @name;
 	pack("n6 (C/a*)$len x n2", $id, $hdr | $rcode, 1, scalar @rdata,
 		0, 0, @name, $type, $class) . join('', @rdata);
 }

 sub rd_name {
 	my ($type, $ttl, $name) = @_;
 	my ($rdlen, @rdname);

 	@rdname = split /\./, $name;
 	$rdlen = length(join '', @rdname) + @rdname + 1;
 	pack("n3N n(C/a*)* x", 0xc00c, $type, IN, $ttl, $rdlen, @rdname);
 }

 sub rd_addr {
 	my ($ttl, $addr) = @_;

 	my $code = 'split(/\./, $addr)';

 	# use a special pack string to not zero pad

 	return pack 'n3N', 0xc00c, A, IN, $ttl if $addr eq '';

 	pack 'n3N nC4', 0xc00c, A, IN, $ttl, eval "scalar $code", eval($code);
 }

 sub dns_daemon {
 	my ($port, $t) = @_;

 	my ($data, $recv_data);
 	my $socket = IO::Socket::INET->new(
 		LocalAddr => '127.0.0.1',
 		LocalPort => $port,
 		Proto => 'udp',
 	)
 		or die "Can't create listening socket: $!\n";

 	# signal we are ready

 	open my $fh, '>', $t->testdir() . '/' . $port;
 	close $fh;

 	while (1) {
 		$socket->recv($recv_data, 65536);
 		$data = reply_handler($recv_data, $port);
 		$socket->send($data);
 	}
 }

 ###############################################################################
	#!/usr/bin/perl

	# (C) Sergey Kandaurov
	# (C) Nginx, Inc.

	# Tests for mail resolver.

	###############################################################################

	use warnings;
	use strict;

	use Test::More;

	BEGIN { use FindBin; chdir($FindBin::Bin); }

	use lib 'lib';
	use Test::Nginx;
	use Test::Nginx::SMTP;

	###############################################################################

	select STDERR; $\| = 1;
	select STDOUT; $\| = 1;

	eval { require IO::Socket::SSL; };
	plan(skip_all => 'IO::Socket::SSL not installed') if $@;
	eval { IO::Socket::SSL::SSL_VERIFY_NONE(); };
	plan(skip_all => 'IO::Socket::SSL too old') if $@;

	local $SIG{PIPE} = 'IGNORE';

	my $t = Test::Nginx->new()->has(qw/mail mail_ssl smtp http rewrite/)
	->has_daemon('openssl')->plan(11)
	->write_file_expand('nginx.conf', <<'EOF');

	%%TEST_GLOBALS%%

	daemon off;

	events {
	}

	mail {
	auth_http http://127.0.0.1:8080/mail/auth;
	smtp_auth none;
	server_name locahost;

	proxy_timeout 15s;

	# prevent useless resend
	resolver_timeout 2s;

	server {
	listen 127.0.0.1:8025;
	protocol smtp;
	resolver 127.0.0.1:%%PORT_8981_UDP%%
	127.0.0.1:%%PORT_8982_UDP%%
	127.0.0.1:%%PORT_8983_UDP%%;
	}

	server {
	listen 127.0.0.1:8027;
	protocol smtp;
	resolver 127.0.0.1:%%PORT_8982_UDP%%;
	}

	server {
	listen 127.0.0.1:8028;
	protocol smtp;
	resolver 127.0.0.1:%%PORT_8983_UDP%%;
	resolver_timeout 1s;
	}

	server {
	listen 127.0.0.1:8029;
	protocol smtp;
	resolver 127.0.0.1:%%PORT_8984_UDP%%;
	}

	server {
	listen 127.0.0.1:8030;
	protocol smtp;
	resolver 127.0.0.1:%%PORT_8985_UDP%%;
	}

	server {
	listen 127.0.0.1:8031;
	protocol smtp;
	resolver 127.0.0.1:%%PORT_8986_UDP%%;
	resolver_timeout 1s;
	}

	server {
	listen 127.0.0.1:8032;
	protocol smtp;
	resolver 127.0.0.1:%%PORT_8987_UDP%%;
	}

	server {
	ssl_certificate_key localhost.key;
	ssl_certificate localhost.crt;

	listen 127.0.0.1:8033 ssl;
	protocol smtp;
	resolver 127.0.0.1:%%PORT_8983_UDP%%;
	}
	}

	http {
	%%TEST_GLOBALS_HTTP%%

	server {
	listen 127.0.0.1:8080;
	server_name localhost;

	location = /mail/auth {
	set $reply $http_client_host;

	if ($http_client_host !~ UNAVAIL) {
	set $reply OK;
	}

	add_header Auth-Status $reply;
	add_header Auth-Server 127.0.0.1;
	add_header Auth-Port %%PORT_8026%%;
	return 204;
	}
	}
	}

	EOF

	$t->write_file('openssl.conf', <<EOF);
	[ req ]
	default_bits = 2048
	encrypt_key = no
	distinguished_name = req_distinguished_name
	[ req_distinguished_name ]
	EOF

	my $d = $t->testdir();

	foreach my $name ('localhost') {
	system('openssl req -x509 -new '
	. "-config $d/openssl.conf -subj /CN=$name/ "
	. "-out $d/$name.crt -keyout $d/$name.key "
	. ">>$d/openssl.out 2>&1") == 0
	or die "Can't create certificate for $name: $!\n";
	}

	$t->run_daemon(\&Test::Nginx::SMTP::smtp_test_daemon);
	$t->run_daemon(\&dns_daemon, port($_), $t) foreach (8981 .. 8987);

	$t->run();

	$t->waitforsocket('127.0.0.1:' . port(8026));
	$t->waitforfile($t->testdir . '/' . port($_)) foreach (8981 .. 8987);

	###############################################################################

	# PTR

	my $s = Test::Nginx::SMTP->new();
	my $s2 = Test::Nginx::SMTP->new();
	$s->read();
	$s->send('EHLO example.com');
	$s->read();
	$s->send('MAIL FROM:<test@example.com> SIZE=100');
	$s->read();

	$s->send('RCPT TO:<test@example.com>');
	$s->ok('PTR');

	$s->send('QUIT');
	$s->read();

	$s2->read();
	$s2->send('EHLO example.com');
	$s2->ok('PTR waiting');

	# Cached PTR prevents from querying bad ns on port 8983

	$s = Test::Nginx::SMTP->new();
	$s->read();
	$s->send('EHLO example.com');
	$s->read();
	$s->send('MAIL FROM:<test@example.com> SIZE=100');
	$s->read();

	$s->send('RCPT TO:<test@example.com>');
	$s->ok('PTR cached');

	$s->send('QUIT');
	$s->read();

	# SERVFAIL

	$s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8027));
	$s->read();
	$s->send('EHLO example.com');
	$s->read();
	$s->send('MAIL FROM:<test@example.com> SIZE=100');
	$s->read();

	$s->send('RCPT TO:<test@example.com>');
	$s->check(qr/TEMPUNAVAIL/, 'PTR SERVFAIL');

	$s->send('QUIT');
	$s->read();

	# PTR with zero length RDATA

	$s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8028));
	$s2 = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8028));
	$s->read();
	$s->send('EHLO example.com');
	$s->read();
	$s->send('MAIL FROM:<test@example.com> SIZE=100');
	$s->read();

	$s->send('RCPT TO:<test@example.com>');
	$s->check(qr/TEMPUNAVAIL/, 'PTR empty');

	$s->send('QUIT');
	$s->read();

	# resolver timeout is set

	$s2->read();
	$s2->send('EHLO example.com');
	$s2->ok('PTR empty waiting');

	# CNAME

	TODO: {
	local $TODO = 'support for CNAME RR';

	$s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8029));
	$s->read();
	$s->send('EHLO example.com');
	$s->read();
	$s->send('MAIL FROM:<test@example.com> SIZE=100');
	$s->read();

	$s->send('RCPT TO:<test@example.com>');
	$s->ok('CNAME');

	$s->send('QUIT');
	$s->read();

	}

	# uncompressed answer

	$s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8030));
	$s->read();
	$s->send('EHLO example.com');
	$s->read();
	$s->send('MAIL FROM:<test@example.com> SIZE=100');
	$s->read();

	$s->send('RCPT TO:<test@example.com>');
	$s->ok('uncompressed PTR');

	$s->send('QUIT');
	$s->read();

	$s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8031));
	$s->read();
	$s->send('EHLO example.com');
	$s->read();
	$s->send('MAIL FROM:<test@example.com> SIZE=100');
	$s->read();

	$s->send('RCPT TO:<test@example.com>');
	$s->check(qr/TEMPUNAVAIL/, 'PTR type');

	$s->send('QUIT');
	$s->read();

	# CNAME and PTR in one answer section

	$s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8032));
	$s->read();
	$s->send('EHLO example.com');
	$s->read();
	$s->send('MAIL FROM:<test@example.com> SIZE=100');
	$s->read();

	$s->send('RCPT TO:<test@example.com>');
	$s->ok('CNAME with PTR');

	$s->send('QUIT');
	$s->read();

	# before 1.17.3, read event while in resolving resulted in duplicate resolving

	TODO: {
	todo_skip 'leaves coredump', 1 unless $ENV{TEST_NGINX_UNSAFE}
	or $t->has_version('1.17.3');

	my %ssl = (
	SSL => 1,
	SSL_verify_mode => IO::Socket::SSL::SSL_VERIFY_NONE(),
	SSL_error_trap => sub { die $_[1] },
	);

	$s = Test::Nginx::SMTP->new(PeerAddr => '127.0.0.1:' . port(8033), %ssl);
	$s->send('EHLO example.com');
	$s->read();
	$s->send('MAIL FROM:<test@example.com> SIZE=100');
	$s->read();
	$s->read();

	$s->send('RCPT TO:<test@example.com>');
	$s->check(qr/TEMPUNAVAIL/, 'PTR SSL empty');

	$s->send('QUIT');
	$s->read();

	}

	###############################################################################

	sub reply_handler {
	my ($recv_data, $port) = @_;

	my (@name, @rdata);

	use constant NOERROR => 0;
	use constant SERVFAIL => 2;
	use constant NXDOMAIN => 3;

	use constant A => 1;
	use constant CNAME => 5;
	use constant PTR => 12;
	use constant DNAME => 39;

	use constant IN => 1;

	# default values

	my ($hdr, $rcode, $ttl) = (0x8180, NOERROR, 3600);

	# decode name

	my ($len, $offset) = (undef, 12);
	while (1) {
	$len = unpack("\@$offset C", $recv_data);
	last if $len == 0;
	$offset++;
	push @name, unpack("\@$offset A$len", $recv_data);
	$offset += $len;
	}

	$offset -= 1;
	my ($id, $type, $class) = unpack("n x$offset n2", $recv_data);

	my $name = join('.', @name);
	if ($name eq 'a.example.net' && $type == A) {
	push @rdata, rd_addr($ttl, '127.0.0.1');

	} elsif ($name eq '1.0.0.127.in-addr.arpa' && $type == PTR) {
	if ($port == port(8981)) {
	push @rdata, rd_name(PTR, $ttl, 'a.example.net');

	} elsif ($port == port(8982)) {
	$rcode = SERVFAIL;

	} elsif ($port == port(8983)) {
	# zero length RDATA

	push @rdata, pack("n3N n", 0xc00c, PTR, IN, $ttl, 0);

	} elsif ($port == port(8984)) {
	# PTR answered with CNAME

	push @rdata, rd_name(CNAME, $ttl,
	'1.1.0.0.127.in-addr.arpa');

	} elsif ($port == port(8985)) {
	# uncompressed answer

	push @rdata, pack("(C/a)6x n2N n(C/a)3x",
	('1', '0', '0', '127', 'in-addr', 'arpa'),
	PTR, IN, $ttl, 15, ('a', 'example', 'net'));

	} elsif ($port == port(8986)) {
	push @rdata, rd_name(DNAME, $ttl, 'a.example.net');

	} elsif ($port == port(8987)) {
	# PTR answered with CNAME+PTR

	push @rdata, rd_name(CNAME, $ttl,
	'1.1.0.0.127.in-addr.arpa');
	push @rdata, pack("n3N n(C/a*)3 x", 0xc034,
	PTR, IN, $ttl, 15, ('a', 'example', 'net'));
	}

	} elsif ($name eq '1.1.0.0.127.in-addr.arpa' && $type == PTR) {
	push @rdata, rd_name(PTR, $ttl, 'a.example.net');
	}

	$len = @name;
	pack("n6 (C/a*)$len x n2", $id, $hdr \| $rcode, 1, scalar @rdata,
	0, 0, @name, $type, $class) . join('', @rdata);
	}

	sub rd_name {
	my ($type, $ttl, $name) = @_;
	my ($rdlen, @rdname);

	@rdname = split /\./, $name;
	$rdlen = length(join '', @rdname) + @rdname + 1;
	pack("n3N n(C/a) x", 0xc00c, $type, IN, $ttl, $rdlen, @rdname);
	}

	sub rd_addr {
	my ($ttl, $addr) = @_;

	my $code = 'split(/\./, $addr)';

	# use a special pack string to not zero pad

	return pack 'n3N', 0xc00c, A, IN, $ttl if $addr eq '';

	pack 'n3N nC4', 0xc00c, A, IN, $ttl, eval "scalar $code", eval($code);
	}

	sub dns_daemon {
	my ($port, $t) = @_;

	my ($data, $recv_data);
	my $socket = IO::Socket::INET->new(
	LocalAddr => '127.0.0.1',
	LocalPort => $port,
	Proto => 'udp',
	)
	or die "Can't create listening socket: $!\n";

	# signal we are ready

	open my $fh, '>', $t->testdir() . '/' . $port;
	close $fh;

	while (1) {
	$socket->recv($recv_data, 65536);
	$data = reply_handler($recv_data, $port);
	$socket->send($data);
	}
	}

	###############################################################################