[ViewVC] Diff of: cvs/AnyEvent/lib/AnyEvent/DNS.pm

Comparing AnyEvent/lib/AnyEvent/DNS.pm (file contents):
Revision 1.2 by root, Fri May 23 02:59:32 2008 UTC vs.
Revision 1.62 by root, Wed Jun 4 11:45:21 2008 UTC

…		…
2		2
3	AnyEvent::DNS - fully asynchronous DNS resolution	3	AnyEvent::DNS - fully asynchronous DNS resolution
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::DNS;	7	use AnyEvent::DNS;
		8
		9	my $cv = AnyEvent->condvar;
		10	AnyEvent::DNS::a "www.google.de", $cv;
		11	# ... later
		12	my @addrs = $cv->recv;
8		13
9	=head1 DESCRIPTION	14	=head1 DESCRIPTION
10		15
11	This module offers both a number of DNS convenience functions as well	16	This module offers both a number of DNS convenience functions as well
12	as a fully asynchronous and high-performance pure-perl stub resolver.	17	as a fully asynchronous and high-performance pure-perl stub resolver.
13		18
		19	The stub resolver supports DNS over IPv4 and IPv6, UDP and TCP, optional
		20	EDNS0 support for up to 4kiB datagrams and automatically falls back to
		21	virtual circuit mode for large responses.
		22
14	=head2 CONVENIENCE FUNCTIONS	23	=head2 CONVENIENCE FUNCTIONS
15		24
16	# none yet
17
18	=over 4	25	=over 4
19		26
20	=cut	27	=cut
21		28
22	package AnyEvent::DNS;	29	package AnyEvent::DNS;
23		30
		31	no warnings;
24	use strict;	32	use strict;
25		33
		34	use Socket qw(AF_INET SOCK_DGRAM SOCK_STREAM);
		35
26	use AnyEvent::Util ();	36	use AnyEvent ();
		37	use AnyEvent::Handle ();
		38	use AnyEvent::Util qw(AF_INET6);
		39
		40	our $VERSION = 4.13;
		41
		42	our @DNS_FALLBACK = (v208.67.220.220, v208.67.222.222);
		43
		44	=item AnyEvent::DNS::a $domain, $cb->(@addrs)
		45
		46	Tries to resolve the given domain to IPv4 address(es).
		47
		48	=item AnyEvent::DNS::aaaa $domain, $cb->(@addrs)
		49
		50	Tries to resolve the given domain to IPv6 address(es).
		51
		52	=item AnyEvent::DNS::mx $domain, $cb->(@hostnames)
		53
		54	Tries to resolve the given domain into a sorted (lower preference value
		55	first) list of domain names.
		56
		57	=item AnyEvent::DNS::ns $domain, $cb->(@hostnames)
		58
		59	Tries to resolve the given domain name into a list of name servers.
		60
		61	=item AnyEvent::DNS::txt $domain, $cb->(@hostnames)
		62
		63	Tries to resolve the given domain name into a list of text records.
		64
		65	=item AnyEvent::DNS::srv $service, $proto, $domain, $cb->(@srv_rr)
		66
		67	Tries to resolve the given service, protocol and domain name into a list
		68	of service records.
		69
		70	Each C<$srv_rr> is an array reference with the following contents:
		71	C<[$priority, $weight, $transport, $target]>.
		72
		73	They will be sorted with lowest priority first, then randomly
		74	distributed by weight as per RFC 2782.
		75
		76	Example:
		77
		78	AnyEvent::DNS::srv "sip", "udp", "schmorp.de", sub { ...
		79	# @_ = ( [10, 10, 5060, "sip1.schmorp.de" ] )
		80
		81	=item AnyEvent::DNS::ptr $domain, $cb->(@hostnames)
		82
		83	Tries to make a PTR lookup on the given domain. See C<reverse_lookup>
		84	and C<reverse_verify> if you want to resolve an IP address to a hostname
		85	instead.
		86
		87	=item AnyEvent::DNS::any $domain, $cb->(@rrs)
		88
		89	Tries to resolve the given domain and passes all resource records found to
		90	the callback.
		91
		92	=item AnyEvent::DNS::reverse_lookup $ipv4_or_6, $cb->(@hostnames)
		93
		94	Tries to reverse-resolve the given IPv4 or IPv6 address (in textual form)
		95	into it's hostname(s). Handles V4MAPPED and V4COMPAT IPv6 addresses
		96	transparently.
		97
		98	=item AnyEvent::DNS::reverse_verify $ipv4_or_6, $cb->(@hostnames)
		99
		100	The same as C<reverse_lookup>, but does forward-lookups to verify that
		101	the resolved hostnames indeed point to the address, which makes spoofing
		102	harder.
		103
		104	If you want to resolve an address into a hostname, this is the preferred
		105	method: The DNS records could still change, but at least this function
		106	verified that the hostname, at one point in the past, pointed at the IP
		107	address you originally resolved.
		108
		109	Example:
		110
		111	AnyEvent::DNS::ptr "2001:500:2f::f", sub { print shift };
		112	# => f.root-servers.net
		113
		114	=cut
		115
		116	sub MAX_PKT() { 4096 } # max packet size we advertise and accept
		117
		118	sub DOMAIN_PORT() { 53 } # if this changes drop me a note
		119
		120	sub resolver;
		121
		122	sub a($$) {
		123	my ($domain, $cb) = @_;
		124
		125	resolver->resolve ($domain => "a", sub {
		126	$cb->(map $_->[3], @_);
		127	});
		128	}
		129
		130	sub aaaa($$) {
		131	my ($domain, $cb) = @_;
		132
		133	resolver->resolve ($domain => "aaaa", sub {
		134	$cb->(map $_->[3], @_);
		135	});
		136	}
		137
		138	sub mx($$) {
		139	my ($domain, $cb) = @_;
		140
		141	resolver->resolve ($domain => "mx", sub {
		142	$cb->(map $_->[4], sort { $a->[3] <=> $b->[3] } @_);
		143	});
		144	}
		145
		146	sub ns($$) {
		147	my ($domain, $cb) = @_;
		148
		149	resolver->resolve ($domain => "ns", sub {
		150	$cb->(map $_->[3], @_);
		151	});
		152	}
		153
		154	sub txt($$) {
		155	my ($domain, $cb) = @_;
		156
		157	resolver->resolve ($domain => "txt", sub {
		158	$cb->(map $_->[3], @_);
		159	});
		160	}
		161
		162	sub srv($$$$) {
		163	my ($service, $proto, $domain, $cb) = @_;
		164
		165	# todo, ask for any and check glue records
		166	resolver->resolve ("_$service._$proto.$domain" => "srv", sub {
		167	my @res;
		168
		169	# classify by priority
		170	my %pri;
		171	push @{ $pri{$_->[3]} }, [ @$_[3,4,5,6] ]
		172	for @_;
		173
		174	# order by priority
		175	for my $pri (sort { $a->[0] <=> $b->[0] } keys %pri) {
		176	# order by weight
		177	my @rr = sort { $a->[1] <=> $b->[1] } @{ delete $pri{$pri} };
		178
		179	my $sum; $sum += $_->[1] for @rr;
		180
		181	while (@rr) {
		182	my $w = int rand $sum + 1;
		183	for (0 .. $#rr) {
		184	if (($w -= $rr[$_][1]) <= 0) {
		185	$sum -= $rr[$_][1];
		186	push @res, splice @rr, $_, 1, ();
		187	last;
		188	}
		189	}
		190	}
		191	}
		192
		193	$cb->(@res);
		194	});
		195	}
		196
		197	sub ptr($$) {
		198	my ($domain, $cb) = @_;
		199
		200	resolver->resolve ($domain => "ptr", sub {
		201	$cb->(map $_->[3], @_);
		202	});
		203	}
		204
		205	sub any($$) {
		206	my ($domain, $cb) = @_;
		207
		208	resolver->resolve ($domain => "*", $cb);
		209	}
		210
		211	# convert textual ip address into reverse lookup form
		212	sub _munge_ptr($) {
		213	my $ipn = $_[0]
		214	or return;
		215
		216	my $ptr;
		217
		218	my $af = AnyEvent::Socket::address_family ($ipn);
		219
		220	if ($af == AF_INET6) {
		221	$ipn = substr $ipn, 0, 16; # anticipate future expansion
		222
		223	# handle v4mapped and v4compat
		224	if ($ipn =~ s/^\x00{10}(?:\xff\xff\|\x00\x00)//) {
		225	$af = AF_INET;
		226	} else {
		227	$ptr = join ".", (reverse split //, unpack "H32", $ipn), "ip6.arpa.";
		228	}
		229	}
		230
		231	if ($af == AF_INET) {
		232	$ptr = join ".", (reverse unpack "C4", $ipn), "in-addr.arpa.";
		233	}
		234
		235	$ptr
		236	}
		237
		238	sub reverse_lookup($$) {
		239	my ($ip, $cb) = @_;
		240
		241	$ip = _munge_ptr AnyEvent::Socket::parse_address ($ip)
		242	or return $cb->();
		243
		244	resolver->resolve ($ip => "ptr", sub {
		245	$cb->(map $_->[3], @_);
		246	});
		247	}
		248
		249	sub reverse_verify($$) {
		250	my ($ip, $cb) = @_;
		251
		252	my $ipn = AnyEvent::Socket::parse_address ($ip)
		253	or return $cb->();
		254
		255	my $af = AnyEvent::Socket::address_family ($ipn);
		256
		257	my @res;
		258	my $cnt;
		259
		260	my $ptr = _munge_ptr $ipn
		261	or return $cb->();
		262
		263	$ip = AnyEvent::Socket::format_address ($ipn); # normalise into the same form
		264
		265	ptr $ptr, sub {
		266	for my $name (@_) {
		267	++$cnt;
		268
		269	# () around AF_INET to work around bug in 5.8
		270	resolver->resolve ("$name." => ($af == (AF_INET) ? "a" : "aaaa"), sub {
		271	for (@_) {
		272	push @res, $name
		273	if $_->[3] eq $ip;
		274	}
		275	$cb->(@res) unless --$cnt;
		276	});
		277	}
		278
		279	$cb->() unless $cnt;
		280	};
		281	}
		282
		283	#################################################################################
27		284
28	=back	285	=back
29		286
30	=head2 DNS EN-/DECODING FUNCTIONS	287	=head2 LOW-LEVEL DNS EN-/DECODING FUNCTIONS
31		288
32	=over 4	289	=over 4
33		290
		291	=item $AnyEvent::DNS::EDNS0
		292
		293	This variable decides whether dns_pack automatically enables EDNS0
		294	support. By default, this is disabled (C<0>), unless overridden by
		295	C<$ENV{PERL_ANYEVENT_EDNS0}>, but when set to C<1>, AnyEvent::DNS will use
		296	EDNS0 in all requests.
		297
34	=cut	298	=cut
		299
		300	our $EDNS0 = $ENV{PERL_ANYEVENT_EDNS0} * 1; # set to 1 to enable (partial) edns0
35		301
36	our %opcode_id = (	302	our %opcode_id = (
37	query => 0,	303	query => 0,
38	iquery => 1,	304	iquery => 1,
39	status => 2,	305	status => 2,
		306	notify => 4,
		307	update => 5,
40	map +($_ => $_), 3..15	308	map +($_ => $_), 3, 6..15
41	);	309	);
42		310
43	our %opcode_str = reverse %opcode_id;	311	our %opcode_str = reverse %opcode_id;
44		312
45	our %rcode_id = (	313	our %rcode_id = (
46	ok => 0,	314	noerror => 0,
47	formerr => 1,	315	formerr => 1,
48	servfail => 2,	316	servfail => 2,
49	nxdomain => 3,	317	nxdomain => 3,
50	notimp => 4,	318	notimp => 4,
51	refused => 5,	319	refused => 5,
		320	yxdomain => 6, # Name Exists when it should not [RFC 2136]
		321	yxrrset => 7, # RR Set Exists when it should not [RFC 2136]
		322	nxrrset => 8, # RR Set that should exist does not [RFC 2136]
		323	notauth => 9, # Server Not Authoritative for zone [RFC 2136]
		324	notzone => 10, # Name not contained in zone [RFC 2136]
		325	# EDNS0 16 BADVERS Bad OPT Version [RFC 2671]
		326	# EDNS0 16 BADSIG TSIG Signature Failure [RFC 2845]
		327	# EDNS0 17 BADKEY Key not recognized [RFC 2845]
		328	# EDNS0 18 BADTIME Signature out of time window [RFC 2845]
		329	# EDNS0 19 BADMODE Bad TKEY Mode [RFC 2930]
		330	# EDNS0 20 BADNAME Duplicate key name [RFC 2930]
		331	# EDNS0 21 BADALG Algorithm not supported [RFC 2930]
52	map +($_ => $_), 6..15	332	map +($_ => $_), 11..15
53	);	333	);
54		334
55	our %rcode_str = reverse %rcode_id;	335	our %rcode_str = reverse %rcode_id;
56		336
57	our %type_id = (	337	our %type_id = (
…		…
71	minfo => 14,	351	minfo => 14,
72	mx => 15,	352	mx => 15,
73	txt => 16,	353	txt => 16,
74	aaaa => 28,	354	aaaa => 28,
75	srv => 33,	355	srv => 33,
		356	naptr => 35, # rfc2915
		357	opt => 41,
		358	spf => 99,
		359	tkey => 249,
		360	tsig => 250,
		361	ixfr => 251,
76	axfr => 252,	362	axfr => 252,
77	mailb => 253,	363	mailb => 253,
78	"*" => 255,	364	"*" => 255,
79	);	365	);
80		366
81	our %type_str = reverse %type_id;	367	our %type_str = reverse %type_id;
82		368
83	our %class_id = (	369	our %class_id = (
84	in => 1,	370	in => 1,
85	ch => 3,	371	ch => 3,
86	hs => 4,	372	hs => 4,
		373	none => 254,
87	"*" => 255,	374	"*" => 255,
88	);	375	);
89		376
90	our %class_str = reverse %class_id;	377	our %class_str = reverse %class_id;
91		378
92	# names MUST have a trailing dot
93	sub _enc_qname($) {	379	sub _enc_name($) {
94	pack "(C/a)*", (split /\./, shift), ""	380	pack "(C/a)", (split /\./, shift), ""
95	}	381	}
96		382
97	sub _enc_qd() {	383	sub _enc_qd() {
98	(_enc_qname $_->[0]) . pack "nn",	384	(_enc_name $_->[0]) . pack "nn",
99	($_->[1] > 0 ? $_->[1] : $type_id {$_->[1]}),	385	($_->[1] > 0 ? $_->[1] : $type_id {$_->[1]}),
100	($_->[2] > 0 ? $_->[2] : $class_id{$_->[2] \|\| "in"})	386	($_->[2] > 0 ? $_->[2] : $class_id{$_->[2] \|\| "in"})
101	}	387	}
102		388
103	sub _enc_rr() {	389	sub _enc_rr() {
104	die "encoding of resource records is not supported";	390	die "encoding of resource records is not supported";
105	}	391	}
106		392
107	=item $pkt = AnyEvent::DNS::dns_pack $dns	393	=item $pkt = AnyEvent::DNS::dns_pack $dns
108		394
109	Packs a perl data structure into a DNS packet. Reading RFC1034 is strongly	395	Packs a perl data structure into a DNS packet. Reading RFC 1035 is strongly
110	recommended, then everything will be totally clear. Or maybe not.	396	recommended, then everything will be totally clear. Or maybe not.
111		397
112	Resource records are not yet encodable.	398	Resource records are not yet encodable.
113		399
114	Examples:	400	Examples:
115		401
116	# very simple request, using lots of default values:	402	# very simple request, using lots of default values:
117	{ rd => 1, qd => [ [ "host.domain", "a"] ] }	403	{ rd => 1, qd => [ [ "host.domain", "a"] ] }
118		404
119	# more complex example, showing how flags etc. are named:	405	# more complex example, showing how flags etc. are named:
120		406
121	{	407	{
122	id => 10000,	408	id => 10000,
123	op => "query",	409	op => "query",
124	rc => "nxdomain",	410	rc => "nxdomain",
125		411
126	# flags	412	# flags
127	qr => 1,	413	qr => 1,
128	aa => 0,	414	aa => 0,
129	tc => 0,	415	tc => 0,
130	rd => 0,	416	rd => 0,
131	ra => 0,	417	ra => 0,
132		418	ad => 0,
		419	cd => 0,
		420
133	qd => [@rr], # query section	421	qd => [@rr], # query section
134	an => [@rr], # answer section	422	an => [@rr], # answer section
135	ns => [@rr], # authority section	423	ns => [@rr], # authority section
136	ar => [@rr], # additional records section	424	ar => [@rr], # additional records section
137	}	425	}
138		426
139	=cut	427	=cut
140		428
141	sub dns_pack($) {	429	sub dns_pack($) {
142	my ($req) = @_;	430	my ($req) = @_;
143		431
144	pack "nn nnnn a* a* a* a*",	432	pack "nn nnnn a* a* a* a* a*",
145	$req->{id},	433	$req->{id},
146		434
147	! !$req->{qr} * 0x8000	435	! !$req->{qr} * 0x8000
148	+ $opcode_id{$req->{op}} * 0x0800	436	+ $opcode_id{$req->{op}} * 0x0800
149	+ ! !$req->{aa} * 0x0400	437	+ ! !$req->{aa} * 0x0400
150	+ ! !$req->{tc} * 0x0200	438	+ ! !$req->{tc} * 0x0200
151	+ ! !$req->{rd} * 0x0100	439	+ ! !$req->{rd} * 0x0100
152	+ ! !$req->{ra} * 0x0080	440	+ ! !$req->{ra} * 0x0080
		441	+ ! !$req->{ad} * 0x0020
		442	+ ! !$req->{cd} * 0x0010
153	+ $rcode_id{$req->{rc}} * 0x0001,	443	+ $rcode_id{$req->{rc}} * 0x0001,
154		444
155	scalar @{ $req->{qd} \|\| [] },	445	scalar @{ $req->{qd} \|\| [] },
156	scalar @{ $req->{an} \|\| [] },	446	scalar @{ $req->{an} \|\| [] },
157	scalar @{ $req->{ns} \|\| [] },	447	scalar @{ $req->{ns} \|\| [] },
158	scalar @{ $req->{ar} \|\| [] },	448	$EDNS0 + scalar @{ $req->{ar} \|\| [] }, # EDNS0 option included here
159		449
160	(join "", map _enc_qd, @{ $req->{qd} \|\| [] }),	450	(join "", map _enc_qd, @{ $req->{qd} \|\| [] }),
161	(join "", map _enc_rr, @{ $req->{an} \|\| [] }),	451	(join "", map _enc_rr, @{ $req->{an} \|\| [] }),
162	(join "", map _enc_rr, @{ $req->{ns} \|\| [] }),	452	(join "", map _enc_rr, @{ $req->{ns} \|\| [] }),
163	(join "", map _enc_rr, @{ $req->{ar} \|\| [] });	453	(join "", map _enc_rr, @{ $req->{ar} \|\| [] }),
		454
		455	($EDNS0 ? pack "C nnNn", 0, 41, MAX_PKT, 0, 0 : "") # EDNS0 option
164	}	456	}
165		457
166	our $ofs;	458	our $ofs;
167	our $pkt;	459	our $pkt;
168		460
169	# bitches	461	# bitches
170	sub _dec_qname {	462	sub _dec_name {
171	my @res;	463	my @res;
172	my $redir;	464	my $redir;
173	my $ptr = $ofs;	465	my $ptr = $ofs;
174	my $cnt;	466	my $cnt;
175		467
176	while () {	468	while () {
177	return undef if ++$cnt >= 256; # to avoid DoS attacks	469	return undef if ++$cnt >= 256; # to avoid DoS attacks
178		470
179	my $len = ord substr $pkt, $ptr++, 1;	471	my $len = ord substr $pkt, $ptr++, 1;
180		472
181	if ($len & 0xc0) {	473	if ($len >= 0xc0) {
182	$ptr++;	474	$ptr++;
183	$ofs = $ptr if $ptr > $ofs;	475	$ofs = $ptr if $ptr > $ofs;
184	$ptr = (unpack "n", substr $pkt, $ptr - 2, 2) & 0x3fff;	476	$ptr = (unpack "n", substr $pkt, $ptr - 2, 2) & 0x3fff;
185	} elsif ($len) {	477	} elsif ($len) {
186	push @res, substr $pkt, $ptr, $len;	478	push @res, substr $pkt, $ptr, $len;
…		…
191	}	483	}
192	}	484	}
193	}	485	}
194		486
195	sub _dec_qd {	487	sub _dec_qd {
196	my $qname = _dec_qname;	488	my $qname = _dec_name;
197	my ($qt, $qc) = unpack "nn", substr $pkt, $ofs; $ofs += 4;	489	my ($qt, $qc) = unpack "nn", substr $pkt, $ofs; $ofs += 4;
198	[$qname, $type_str{$qt} \|\| $qt, $class_str{$qc} \|\| $qc]	490	[$qname, $type_str{$qt} \|\| $qt, $class_str{$qc} \|\| $qc]
199	}	491	}
200		492
201	our %dec_rr = (	493	our %dec_rr = (
202	1 => sub { Socket::inet_ntoa $_ }, # a	494	1 => sub { join ".", unpack "C4", $_ }, # a
203	2 => sub { local $ofs = $ofs - length; _dec_qname }, # ns	495	2 => sub { local $ofs = $ofs - length; _dec_name }, # ns
204	5 => sub { local $ofs = $ofs - length; _dec_qname }, # cname	496	5 => sub { local $ofs = $ofs - length; _dec_name }, # cname
205	6 => sub {	497	6 => sub {
206	local $ofs = $ofs - length;	498	local $ofs = $ofs - length;
207	my $mname = _dec_qname;	499	my $mname = _dec_name;
208	my $rname = _dec_qname;	500	my $rname = _dec_name;
209	($mname, $rname, unpack "NNNNN", substr $pkt, $ofs)	501	($mname, $rname, unpack "NNNNN", substr $pkt, $ofs)
210	}, # soa	502	}, # soa
211	11 => sub { ((Socket::inet_aton substr $_, 0, 4), unpack "C a*", substr $_, 4) }, # wks	503	11 => sub { ((join ".", unpack "C4", $_), unpack "C a*", substr $_, 4) }, # wks
212	12 => sub { local $ofs = $ofs - length; _dec_qname }, # ptr	504	12 => sub { local $ofs = $ofs - length; _dec_name }, # ptr
213	13 => sub { unpack "C/a C/a", $_ },	505	13 => sub { unpack "C/a* C/a*", $_ }, # hinfo
214	15 => sub { local $ofs = $ofs + 2 - length; ((unpack "n", $_), _dec_qname) }, # mx	506	15 => sub { local $ofs = $ofs + 2 - length; ((unpack "n", $_), _dec_name) }, # mx
215	16 => sub { unpack "C/a", $_ }, # txt	507	16 => sub { unpack "(C/a)", $_ }, # txt
216	28 => sub { sprintf "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x", unpack "n8" }, # aaaa	508	28 => sub { AnyEvent::Socket::format_address ($_) }, # aaaa
217	33 => sub { local $ofs = $ofs + 6 - length; ((unpack "nnn", $_), _dec_qname) }, # srv	509	33 => sub { local $ofs = $ofs + 6 - length; ((unpack "nnn", $_), _dec_name) }, # srv
		510	35 => sub { # naptr
		511	my ($order, $preference, $flags, $service, $regexp, $offset) = unpack "nn C/a* C/a* C/a* .", $_;
		512	local $ofs = $ofs + $offset - length;
		513	($order, $preference, $flags, $service, $regexp, _dec_name)
		514	},
		515	99 => sub { unpack "(C/a)", $_ }, # spf
218	);	516	);
219		517
220	sub _dec_rr {	518	sub _dec_rr {
221	my $qname = _dec_qname;	519	my $name = _dec_name;
222		520
223	my ($rt, $rc, $ttl, $rdlen) = unpack "nn N n", substr $pkt, $ofs; $ofs += 10;	521	my ($rt, $rc, $ttl, $rdlen) = unpack "nn N n", substr $pkt, $ofs; $ofs += 10;
224	local $_ = substr $pkt, $ofs, $rdlen; $ofs += $rdlen;	522	local $_ = substr $pkt, $ofs, $rdlen; $ofs += $rdlen;
225		523
226	[	524	[
227	$qname,	525	$name,
228	$type_str{$rt} \|\| $rt,	526	$type_str{$rt} \|\| $rt,
229	$class_str{$rc} \|\| $rc,	527	$class_str{$rc} \|\| $rc,
230	($dec_rr{$rt} \|\| sub { $_ })->(),	528	($dec_rr{$rt} \|\| sub { $_ })->(),
231	]	529	]
232	}	530	}
…		…
235		533
236	Unpacks a DNS packet into a perl data structure.	534	Unpacks a DNS packet into a perl data structure.
237		535
238	Examples:	536	Examples:
239		537
240	# a non-successful reply	538	# an unsuccessful reply
241	{	539	{
242	'qd' => [	540	'qd' => [
243	[ 'ruth.plan9.de.mach.uni-karlsruhe.de', '*', 'in' ]	541	[ 'ruth.plan9.de.mach.uni-karlsruhe.de', '*', 'in' ]
244	],	542	],
245	'rc' => 'nxdomain',	543	'rc' => 'nxdomain',
246	'ar' => [],	544	'ar' => [],
247	'ns' => [	545	'ns' => [
248	[	546	[
249	'uni-karlsruhe.de',	547	'uni-karlsruhe.de',
250	'soa',	548	'soa',
251	'in',	549	'in',
252	'netserv.rz.uni-karlsruhe.de',	550	'netserv.rz.uni-karlsruhe.de',
253	'hostmaster.rz.uni-karlsruhe.de',	551	'hostmaster.rz.uni-karlsruhe.de',
254	2008052201,	552	2008052201, 10800, 1800, 2592000, 86400
255	10800,
256	1800,
257	2592000,
258	86400
259	]	553	]
260	],	554	],
261	'tc' => '',	555	'tc' => '',
262	'ra' => 1,	556	'ra' => 1,
263	'qr' => 1,	557	'qr' => 1,
264	'id' => 45915,	558	'id' => 45915,
265	'aa' => '',	559	'aa' => '',
266	'an' => [],	560	'an' => [],
267	'rd' => 1,	561	'rd' => 1,
268	'op' => 'query'	562	'op' => 'query'
269	}	563	}
270		564
271	# a successful reply	565	# a successful reply
272		566
273	{	567	{
274	'qd' => [ [ 'www.google.de', 'a', 'in' ] ],	568	'qd' => [ [ 'www.google.de', 'a', 'in' ] ],
275	'rc' => 0,	569	'rc' => 0,
276	'ar' => [	570	'ar' => [
277	[ 'a.l.google.com', 'a', 'in', '209.85.139.9' ],	571	[ 'a.l.google.com', 'a', 'in', '209.85.139.9' ],
278	[ 'b.l.google.com', 'a', 'in', '64.233.179.9' ],	572	[ 'b.l.google.com', 'a', 'in', '64.233.179.9' ],
279	[ 'c.l.google.com', 'a', 'in', '64.233.161.9' ],	573	[ 'c.l.google.com', 'a', 'in', '64.233.161.9' ],
280	],	574	],
281	'ns' => [	575	'ns' => [
282	[ 'l.google.com', 'ns', 'in', 'a.l.google.com' ],	576	[ 'l.google.com', 'ns', 'in', 'a.l.google.com' ],
283	[ 'l.google.com', 'ns', 'in', 'b.l.google.com' ],	577	[ 'l.google.com', 'ns', 'in', 'b.l.google.com' ],
284	],	578	],
285	'tc' => '',	579	'tc' => '',
286	'ra' => 1,	580	'ra' => 1,
287	'qr' => 1,	581	'qr' => 1,
288	'id' => 64265,	582	'id' => 64265,
289	'aa' => '',	583	'aa' => '',
290	'an' => [	584	'an' => [
291	[ 'www.google.de', 'cname', 'in', 'www.google.com' ],	585	[ 'www.google.de', 'cname', 'in', 'www.google.com' ],
292	[ 'www.google.com', 'cname', 'in', 'www.l.google.com' ],	586	[ 'www.google.com', 'cname', 'in', 'www.l.google.com' ],
293	[ 'www.l.google.com', 'a', 'in', '66.249.93.104' ],	587	[ 'www.l.google.com', 'a', 'in', '66.249.93.104' ],
294	[ 'www.l.google.com', 'a', 'in', '66.249.93.147' ],	588	[ 'www.l.google.com', 'a', 'in', '66.249.93.147' ],
295	],	589	],
296	'rd' => 1,	590	'rd' => 1,
297	'op' => 0	591	'op' => 0
298	}	592	}
299		593
300	=cut	594	=cut
301		595
302	sub dns_unpack($) {	596	sub dns_unpack($) {
303	local $pkt = shift;	597	local $pkt = shift;
…		…
311	qr => ! ! ($flags & 0x8000),	605	qr => ! ! ($flags & 0x8000),
312	aa => ! ! ($flags & 0x0400),	606	aa => ! ! ($flags & 0x0400),
313	tc => ! ! ($flags & 0x0200),	607	tc => ! ! ($flags & 0x0200),
314	rd => ! ! ($flags & 0x0100),	608	rd => ! ! ($flags & 0x0100),
315	ra => ! ! ($flags & 0x0080),	609	ra => ! ! ($flags & 0x0080),
		610	ad => ! ! ($flags & 0x0020),
		611	cd => ! ! ($flags & 0x0010),
316	op => $opcode_str{($flags & 0x001e) >> 11},	612	op => $opcode_str{($flags & 0x001e) >> 11},
317	rc => $rcode_str{($flags & 0x000f)},	613	rc => $rcode_str{($flags & 0x000f)},
318		614
319	qd => [map _dec_qd, 1 .. $qd],	615	qd => [map _dec_qd, 1 .. $qd],
320	an => [map _dec_rr, 1 .. $an],	616	an => [map _dec_rr, 1 .. $an],
…		…
327		623
328	=back	624	=back
329		625
330	=head2 THE AnyEvent::DNS RESOLVER CLASS	626	=head2 THE AnyEvent::DNS RESOLVER CLASS
331		627
332	This is the class which deos the actual protocol work.	628	This is the class which does the actual protocol work.
333		629
334	=over 4	630	=over 4
335		631
336	=cut	632	=cut
337		633
…		…
357	our $RESOLVER;	653	our $RESOLVER;
358		654
359	sub resolver() {	655	sub resolver() {
360	$RESOLVER \|\| do {	656	$RESOLVER \|\| do {
361	$RESOLVER = new AnyEvent::DNS;	657	$RESOLVER = new AnyEvent::DNS;
362	$RESOLVER->load_resolv_conf;	658	$RESOLVER->os_config;
363	$RESOLVER	659	$RESOLVER
364	}	660	}
365	}	661	}
366		662
367	=item $resolver = new AnyEvent::DNS key => value...	663	=item $resolver = new AnyEvent::DNS key => value...
368		664
369	Creates and returns a new resolver. It only supports UDP, so make sure	665	Creates and returns a new resolver.
370	your answer sections fit into a DNS packet.
371		666
372	The following options are supported:	667	The following options are supported:
373		668
374	=over 4	669	=over 4
375		670
376	=item server => [...]	671	=item server => [...]
377		672
378	A list of server addressses (default C<v127.0.0.1>) in network format (4	673	A list of server addresses (default: C<v127.0.0.1>) in network format
379	octets for IPv4, 16 octets for IPv6 - not yet supported).	674	(i.e. as returned by C<AnyEvent::Socket::parse_address> - both IPv4 and
		675	IPv6 are supported).
380		676
381	=item timeout => [...]	677	=item timeout => [...]
382		678
383	A list of timeouts to use (also determines the number of retries). To make	679	A list of timeouts to use (also determines the number of retries). To make
384	three retries with individual time-outs of 2, 5 and 5 seconds, use C<[2,	680	three retries with individual time-outs of 2, 5 and 5 seconds, use C<[2,
…		…
393	The number of dots (default: C<1>) that a name must have so that the resolver	689	The number of dots (default: C<1>) that a name must have so that the resolver
394	tries to resolve the name without any suffixes first.	690	tries to resolve the name without any suffixes first.
395		691
396	=item max_outstanding => $integer	692	=item max_outstanding => $integer
397		693
398	Most name servers do not handle many parallel requests very well. This option	694	Most name servers do not handle many parallel requests very well. This
399	limits the numbe rof outstanding requests to C<$n> (default: C<10>), that means	695	option limits the number of outstanding requests to C<$integer>
400	if you request more than this many requests, then the additional requests will be queued	696	(default: C<10>), that means if you request more than this many requests,
401	until some other requests have been resolved.	697	then the additional requests will be queued until some other requests have
		698	been resolved.
		699
		700	=item reuse => $seconds
		701
		702	The number of seconds (default: C<300>) that a query id cannot be re-used
		703	after a timeout. If there was no time-out then query ids can be reused
		704	immediately.
402		705
403	=back	706	=back
404		707
405	=cut	708	=cut
406		709
407	sub new {	710	sub new {
408	my ($class, %arg) = @_;	711	my ($class, %arg) = @_;
409		712
		713	# try to create a ipv4 and an ipv6 socket
		714	# only fail when we cnanot create either
		715
410	socket my $fh, &Socket::AF_INET, &Socket::SOCK_DGRAM, 0	716	socket my $fh4, AF_INET , &Socket::SOCK_DGRAM, 0;
411	or Carp::croak "socket: $!";	717	socket my $fh6, AF_INET6, &Socket::SOCK_DGRAM, 0;
412		718
413	AnyEvent::Util::fh_nonblocking $fh, 1;	719	$fh4 \|\| $fh6
		720	or Carp::croak "unable to create either an IPv6 or an IPv4 socket";
414		721
415	my $self = bless {	722	my $self = bless {
416	server => [v127.0.0.1],	723	server => [],
417	timeout => [2, 5, 5],	724	timeout => [2, 5, 5],
418	search => [],	725	search => [],
419	ndots => 1,	726	ndots => 1,
420	max_outstanding => 10,	727	max_outstanding => 10,
421	reuse => 300, # reuse id's after 5 minutes only, if possible	728	reuse => 300,
422	%arg,	729	%arg,
423	fh => $fh,
424	reuse_q => [],	730	reuse_q => [],
425	}, $class;	731	}, $class;
426		732
427	# search should default to gethostname's domain	733	# search should default to gethostname's domain
428	# but perl lacks a good posix module	734	# but perl lacks a good posix module
429		735
430	Scalar::Util::weaken (my $wself = $self);	736	Scalar::Util::weaken (my $wself = $self);
		737
		738	if ($fh4) {
		739	AnyEvent::Util::fh_nonblocking $fh4, 1;
		740	$self->{fh4} = $fh4;
431	$self->{rw} = AnyEvent->io (fh => $fh, poll => "r", cb => sub { $wself->_recv });	741	$self->{rw4} = AnyEvent->io (fh => $fh4, poll => "r", cb => sub {
		742	if (my $peer = recv $fh4, my $pkt, MAX_PKT, 0) {
		743	$wself->_recv ($pkt, $peer);
		744	}
		745	});
		746	}
		747
		748	if ($fh6) {
		749	$self->{fh6} = $fh6;
		750	AnyEvent::Util::fh_nonblocking $fh6, 1;
		751	$self->{rw6} = AnyEvent->io (fh => $fh6, poll => "r", cb => sub {
		752	if (my $peer = recv $fh6, my $pkt, MAX_PKT, 0) {
		753	$wself->_recv ($pkt, $peer);
		754	}
		755	});
		756	}
432		757
433	$self->_compile;	758	$self->_compile;
434		759
435	$self	760	$self
436	}	761	}
437		762
438	=item $resolver->parse_resolv_conv ($string)	763	=item $resolver->parse_resolv_conv ($string)
439		764
440	Parses the given string a sif it were a F<resolv.conf> file. The following	765	Parses the given string as if it were a F<resolv.conf> file. The following
441	directives are supported:	766	directives are supported (but not necessarily implemented).
442		767
443	C<#>-style comments, C<nameserver>, C<domain>, C<search>, C<sortlist>,	768	C<#>-style comments, C<nameserver>, C<domain>, C<search>, C<sortlist>,
444	C<options> (C<timeout>, C<attempts>, C<ndots>).	769	C<options> (C<timeout>, C<attempts>, C<ndots>).
445		770
446	Everything else is silently ignored.	771	Everything else is silently ignored.
…		…
458	for (split /\n/, $resolvconf) {	783	for (split /\n/, $resolvconf) {
459	if (/^\s*#/) {	784	if (/^\s*#/) {
460	# comment	785	# comment
461	} elsif (/^\snameserver\s+(\S+)\s$/i) {	786	} elsif (/^\snameserver\s+(\S+)\s$/i) {
462	my $ip = $1;	787	my $ip = $1;
463	if (AnyEvent::Util::dotted_quad $ip) {	788	if (my $ipn = AnyEvent::Socket::parse_address ($ip)) {
464	push @{ $self->{server} }, AnyEvent::Util::socket_inet_aton $ip;	789	push @{ $self->{server} }, $ipn;
465	} else {	790	} else {
466	warn "nameserver $ip invalid and ignored\n";	791	warn "nameserver $ip invalid and ignored\n";
467	}	792	}
468	} elsif (/^\sdomain\s+(\S)\s+$/i) {	793	} elsif (/^\sdomain\s+(\S)\s+$/i) {
469	$self->{search} = [$1];	794	$self->{search} = [$1];
…		…
490	if $attempts;	815	if $attempts;
491		816
492	$self->_compile;	817	$self->_compile;
493	}	818	}
494		819
495	=item $resolver->load_resolv_conf	820	=item $resolver->os_config
496		821
497	Tries to load and parse F</etc/resolv.conf>. If there will ever be windows	822	Tries so load and parse F</etc/resolv.conf> on portable operating systems. Tries various
498	support, then this function will do the right thing under windows, too.	823	egregious hacks on windows to force the DNS servers and searchlist out of the system.
499		824
500	=cut	825	=cut
501		826
502	sub load_resolv_conf {	827	sub os_config {
503	my ($self) = @_;	828	my ($self) = @_;
504		829
		830	$self->{server} = [];
		831	$self->{search} = [];
		832
		833	if (AnyEvent::WIN32 \|\| $^O =~ /cygwin/i) {
		834	no strict 'refs';
		835
		836	# there are many options to find the current nameservers etc. on windows
		837	# all of them don't work consistently:
		838	# - the registry thing needs separate code on win32 native vs. cygwin
		839	# - the registry layout differs between windows versions
		840	# - calling windows api functions doesn't work on cygwin
		841	# - ipconfig uses locale-specific messages
		842
		843	# we use ipconfig parsing because, despite all its brokenness,
		844	# it seems most stable in practise.
		845	# for good measure, we append a fallback nameserver to our list.
		846
		847	if (open my $fh, "ipconfig /all \|") {
		848	# parsing strategy: we go through the output and look for
		849	# :-lines with DNS in them. everything in those is regarded as
		850	# either a nameserver (if it parses as an ip address), or a suffix
		851	# (all else).
		852
		853	my $dns;
		854	while (<$fh>) {
		855	if (s/^\s.\bdns\b.://i) {
		856	$dns = 1;
		857	} elsif (/^\S/ \|\| /^\s[^:]{16,}: /) {
		858	$dns = 0;
		859	}
		860	if ($dns && /^\s(\S+)\s$/) {
		861	my $s = $1;
		862	$s =~ s/%\d+(?!\S)//; # get rid of ipv6 scope id
		863	if (my $ipn = AnyEvent::Socket::parse_address ($s)) {
		864	push @{ $self->{server} }, $ipn;
		865	} else {
		866	push @{ $self->{search} }, $s;
		867	}
		868	}
		869	}
		870
		871	# always add one fallback server
		872	push @{ $self->{server} }, $DNS_FALLBACK[rand @DNS_FALLBACK];
		873
		874	$self->_compile;
		875	}
		876	} else {
		877	# try resolv.conf everywhere
		878
505	open my $fh, "</etc/resolv.conf"	879	if (open my $fh, "</etc/resolv.conf") {
506	or return;
507
508	local $/;	880	local $/;
509	$self->parse_resolv_conf (<$fh>);	881	$self->parse_resolv_conf (<$fh>);
		882	}
		883	}
		884	}
		885
		886	=item $resolver->timeout ($timeout, ...)
		887
		888	Sets the timeout values. See the C<timeout> constructor argument (and note
		889	that this method uses the values itself, not an array-reference).
		890
		891	=cut
		892
		893	sub timeout {
		894	my ($self, @timeout) = @_;
		895
		896	$self->{timeout} = \@timeout;
		897	$self->_compile;
		898	}
		899
		900	=item $resolver->max_outstanding ($nrequests)
		901
		902	Sets the maximum number of outstanding requests to C<$nrequests>. See the
		903	C<max_outstanding> constructor argument.
		904
		905	=cut
		906
		907	sub max_outstanding {
		908	my ($self, $max) = @_;
		909
		910	$self->{max_outstanding} = $max;
		911	$self->_scheduler;
510	}	912	}
511		913
512	sub _compile {	914	sub _compile {
513	my $self = shift;	915	my $self = shift;
		916
		917	my %search; $self->{search} = [grep 0 < length, grep !$search{$_}++, @{ $self->{search} }];
		918	my %server; $self->{server} = [grep 0 < length, grep !$server{$_}++, @{ $self->{server} }];
		919
		920	unless (@{ $self->{server} }) {
		921	# use 127.0.0.1 by default, and one opendns nameserver as fallback
		922	$self->{server} = [v127.0.0.1, $DNS_FALLBACK[rand @DNS_FALLBACK]];
		923	}
514		924
515	my @retry;	925	my @retry;
516		926
517	for my $timeout (@{ $self->{timeout} }) {	927	for my $timeout (@{ $self->{timeout} }) {
518	for my $server (@{ $self->{server} }) {	928	for my $server (@{ $self->{server} }) {
…		…
521	}	931	}
522		932
523	$self->{retry} = \@retry;	933	$self->{retry} = \@retry;
524	}	934	}
525		935
		936	sub _feed {
		937	my ($self, $res) = @_;
		938
		939	$res = dns_unpack $res
		940	or return;
		941
		942	my $id = $self->{id}{$res->{id}};
		943
		944	return unless ref $id;
		945
		946	$NOW = time;
		947	$id->[1]->($res);
		948	}
		949
526	sub _recv {	950	sub _recv {
527	my ($self) = @_;	951	my ($self, $pkt, $peer) = @_;
528		952
529	while (my $peer = recv $self->{fh}, my $res, 1024, 0) {	953	# we ignore errors (often one gets port unreachable, but there is
		954	# no good way to take advantage of that.
		955
530	my ($port, $host) = Socket::unpack_sockaddr_in $peer;	956	my ($port, $host) = AnyEvent::Socket::unpack_sockaddr ($peer);
531		957
532	return unless $port == 53 && grep $_ eq $host, @{ $self->{server} };	958	return unless $port == 53 && grep $_ eq $host, @{ $self->{server} };
533		959
534	$res = AnyEvent::DNS::dns_unpack $res	960	$self->_feed ($pkt);
535	or return;
536
537	my $id = $self->{id}{$res->{id}};
538
539	return unless ref $id;
540
541	$NOW = time;
542	$id->[1]->($res);
543	}
544	}	961	}
545		962
		963	sub _free_id {
		964	my ($self, $id, $timeout) = @_;
		965
		966	if ($timeout) {
		967	# we need to block the id for a while
		968	$self->{id}{$id} = 1;
		969	push @{ $self->{reuse_q} }, [$NOW + $self->{reuse}, $id];
		970	} else {
		971	# we can quickly recycle the id
		972	delete $self->{id}{$id};
		973	}
		974
		975	--$self->{outstanding};
		976	$self->_scheduler;
		977	}
		978
		979	# execute a single request, involves sending it with timeouts to multiple servers
546	sub _exec {	980	sub _exec {
547	my ($self, $req, $retry) = @_;	981	my ($self, $req) = @_;
548		982
		983	my $retry; # of retries
		984	my $do_retry;
		985
		986	$do_retry = sub {
549	if (my $retry_cfg = $self->{retry}[$retry]) {	987	my $retry_cfg = $self->{retry}[$retry++]
		988	or do {
		989	# failure
		990	$self->_free_id ($req->[2], $retry > 1);
		991	undef $do_retry; return $req->[1]->();
		992	};
		993
550	my ($server, $timeout) = @$retry_cfg;	994	my ($server, $timeout) = @$retry_cfg;
551		995
552	$self->{id}{$req->[2]} = [AnyEvent->timer (after => $timeout, cb => sub {	996	$self->{id}{$req->[2]} = [AnyEvent->timer (after => $timeout, cb => sub {
553	$NOW = time;	997	$NOW = time;
554		998
555	# timeout, try next	999	# timeout, try next
556	$self->_exec ($req, $retry + 1);	1000	&$do_retry;
557	}), sub {	1001	}), sub {
558	my ($res) = @_;	1002	my ($res) = @_;
559		1003
		1004	if ($res->{tc}) {
		1005	# success, but truncated, so use tcp
		1006	AnyEvent::Socket::tcp_connect (AnyEvent::Socket::format_address ($server), DOMAIN_PORT, sub {
		1007	return unless $do_retry; # some other request could have invalidated us already
		1008
		1009	my ($fh) = @_
		1010	or return &$do_retry;
		1011
		1012	my $handle; $handle = new AnyEvent::Handle
		1013	fh => $fh,
		1014	timeout => $timeout,
		1015	on_error => sub {
		1016	undef $handle;
		1017	return unless $do_retry; # some other request could have invalidated us already
		1018	# failure, try next
		1019	&$do_retry;
		1020	};
		1021
		1022	$handle->push_write (pack "n/a", $req->[0]);
		1023	$handle->push_read (chunk => 2, sub {
		1024	$handle->unshift_read (chunk => (unpack "n", $_[1]), sub {
		1025	undef $handle;
		1026	$self->_feed ($_[1]);
		1027	});
		1028	});
		1029
		1030	}, sub { $timeout });
		1031
		1032	} else {
560	# success	1033	# success
561	$self->{id}{$req->[2]} = 1;	1034	$self->_free_id ($req->[2], $retry > 1);
562	push @{ $self->{reuse_q} }, [$NOW + $self->{reuse}, $req->[2]];	1035	undef $do_retry; return $req->[1]->($res);
563	--$self->{outstanding};	1036	}
564	$self->_scheduler;
565
566	$req->[1]->($res);
567	}];	1037	}];
		1038
		1039	my $sa = AnyEvent::Socket::pack_sockaddr (DOMAIN_PORT, $server);
568		1040
569	send $self->{fh}, $req->[0], 0, Socket::pack_sockaddr_in 53, $server;	1041	my $fh = AF_INET == Socket::sockaddr_family ($sa)
570	} else {	1042	? $self->{fh4} : $self->{fh6}
571	# failure	1043	or return &$do_retry;
572	$self->{id}{$req->[2]} = 1;
573	push @{ $self->{reuse_q} }, [$NOW + $self->{reuse}, $req->[2]];
574	--$self->{outstanding};
575	$self->_scheduler;
576		1044
577	$req->[1]->();	1045	send $fh, $req->[0], 0, $sa;
578	}	1046	};
		1047
		1048	&$do_retry;
579	}	1049	}
580		1050
581	sub _scheduler {	1051	sub _scheduler {
582	my ($self) = @_;	1052	my ($self) = @_;
583		1053
		1054	no strict 'refs';
		1055
584	$NOW = time;	1056	$NOW = time;
585		1057
586	# first clear id reuse queue	1058	# first clear id reuse queue
587	delete $self->{id}{ (shift @{ $self->{reuse_q} })->[1] }	1059	delete $self->{id}{ (shift @{ $self->{reuse_q} })->[1] }
588	while @{ $self->{reuse_q} } && $self->{reuse_q}[0] <= $NOW;	1060	while @{ $self->{reuse_q} } && $self->{reuse_q}[0][0] <= $NOW;
589		1061
590	while ($self->{outstanding} < $self->{max_outstanding}) {	1062	while ($self->{outstanding} < $self->{max_outstanding}) {
591	my $req = shift @{ $self->{queue} }	1063
		1064	if (@{ $self->{reuse_q} } >= 30000) {
		1065	# we ran out of ID's, wait a bit
		1066	$self->{reuse_to} \|\|= AnyEvent->timer (after => $self->{reuse_q}[0][0] - $NOW, cb => sub {
		1067	delete $self->{reuse_to};
		1068	$self->_scheduler;
		1069	});
592	or last;	1070	last;
593
594	while () {
595	$req->[2] = int rand 65536;
596	last unless exists $self->{id}{$req->[2]};
597	}	1071	}
598		1072
		1073	if (my $req = shift @{ $self->{queue} }) {
		1074	# found a request in the queue, execute it
		1075	while () {
		1076	$req->[2] = int rand 65536;
		1077	last unless exists $self->{id}{$req->[2]};
		1078	}
		1079
		1080	++$self->{outstanding};
599	$self->{id}{$req->[2]} = 1;	1081	$self->{id}{$req->[2]} = 1;
600	substr $req->[0], 0, 2, pack "n", $req->[2];	1082	substr $req->[0], 0, 2, pack "n", $req->[2];
601		1083
602	++$self->{outstanding};
603	$self->_exec ($req, 0);	1084	$self->_exec ($req);
		1085
		1086	} elsif (my $cb = shift @{ $self->{wait} }) {
		1087	# found a wait_for_slot callback, call that one first
		1088	$cb->($self);
		1089
		1090	} else {
		1091	# nothing to do, just exit
		1092	last;
		1093	}
604	}	1094	}
605	}	1095	}
606		1096
607	=item $resolver->request ($req, $cb->($res))	1097	=item $resolver->request ($req, $cb->($res))
608		1098
		1099	This is the main low-level workhorse for sending DNS requests.
		1100
609	Sends a single request (a hash-ref formated as specified for	1101	This function sends a single request (a hash-ref formated as specified
610	C<AnyEvent::DNS::dns_pack>) to the configured nameservers including	1102	for C<dns_pack>) to the configured nameservers in turn until it gets a
		1103	response. It handles timeouts, retries and automatically falls back to
		1104	virtual circuit mode (TCP) when it receives a truncated reply.
		1105
611	retries. Calls the callback with the decoded response packet if a reply	1106	Calls the callback with the decoded response packet if a reply was
612	was received, or no arguments on timeout.	1107	received, or no arguments in case none of the servers answered.
613		1108
614	=cut	1109	=cut
615		1110
616	sub request($$) {	1111	sub request($$) {
617	my ($self, $req, $cb) = @_;	1112	my ($self, $req, $cb) = @_;
618		1113
619	push @{ $self->{queue} }, [(AnyEvent::DNS::dns_pack $req), $cb];	1114	push @{ $self->{queue} }, [dns_pack $req, $cb];
620	$self->_scheduler;	1115	$self->_scheduler;
621	}	1116	}
622		1117
623	=item $resolver->resolve ($qname, $qtype, %options, $cb->($rcode, @rr))	1118	=item $resolver->resolve ($qname, $qtype, %options, $cb->($rcode, @rr))
624		1119
625	Queries the DNS for the given domain name C<$qname> of type C<$qtype> (a	1120	Queries the DNS for the given domain name C<$qname> of type C<$qtype>.
626	qtype of "*" is supported and means "any").	1121
		1122	A C<$qtype> is either a numerical query type (e.g. C<1> for A records) or
		1123	a lowercase name (you have to look at the source to see which aliases are
		1124	supported, but all types from RFC 1035, C<aaaa>, C<srv>, C<spf> and a few
		1125	more are known to this module). A C<$qtype> of "*" is supported and means
		1126	"any" record type.
627		1127
628	The callback will be invoked with a list of matching result records or	1128	The callback will be invoked with a list of matching result records or
629	none on any error or if the name could not be found.	1129	none on any error or if the name could not be found.
630		1130
631	CNAME chains (although illegal) are followed up to a length of 8.	1131	CNAME chains (although illegal) are followed up to a length of 10.
		1132
		1133	The callback will be invoked with an result code in string form (noerror,
		1134	formerr, servfail, nxdomain, notimp, refused and so on), or numerical
		1135	form if the result code is not supported. The remaining arguments are
		1136	arraryefs of the form C<[$name, $type, $class, @data>], where C<$name> is
		1137	the domain name, C<$type> a type string or number, C<$class> a class name
		1138	and @data is resource-record-dependent data. For C<a> records, this will
		1139	be the textual IPv4 addresses, for C<ns> or C<cname> records this will be
		1140	a domain name, for C<txt> records these are all the strings and so on.
		1141
		1142	All types mentioned in RFC 1035, C<aaaa>, C<srv>, C<naptr> and C<spf> are
		1143	decoded. All resource records not known to this module will have
		1144	the raw C<rdata> field as fourth entry.
		1145
		1146	Note that this resolver is just a stub resolver: it requires a name server
		1147	supporting recursive queries, will not do any recursive queries itself and
		1148	is not secure when used against an untrusted name server.
632		1149
633	The following options are supported:	1150	The following options are supported:
634		1151
635	=over 4	1152	=over 4
636		1153
637	=item search => [$suffix...]	1154	=item search => [$suffix...]
638		1155
639	Use the given search list (which might be empty), by appending each one	1156	Use the given search list (which might be empty), by appending each one
640	in turn to the C<$qname>. If this option is missing then the configured	1157	in turn to the C<$qname>. If this option is missing then the configured
641	C<ndots> and C<search> define its value. If the C<$qname> ends in a dot,	1158	C<ndots> and C<search> values define its value (depending on C<ndots>, the
642	then the searchlist will be ignored.	1159	empty suffix will be prepended or appended to that C<search> value). If
		1160	the C<$qname> ends in a dot, then the searchlist will be ignored.
643		1161
644	=item accept => [$type...]	1162	=item accept => [$type...]
645		1163
646	Lists the acceptable result types: only result types in this set will be	1164	Lists the acceptable result types: only result types in this set will be
647	accepted and returned. The default includes the C<$qtype> and nothing	1165	accepted and returned. The default includes the C<$qtype> and nothing
648	else.	1166	else. If this list includes C<cname>, then CNAME-chains will not be
		1167	followed (because you asked for the CNAME record).
649		1168
650	=item class => "class"	1169	=item class => "class"
651		1170
652	Specify the query class ("in" for internet, "ch" for chaosnet and "hs" for	1171	Specify the query class ("in" for internet, "ch" for chaosnet and "hs" for
653	hesiod are the only ones making sense). The default is "in", of course.	1172	hesiod are the only ones making sense). The default is "in", of course.
654		1173
655	=back	1174	=back
656		1175
657	Examples:	1176	Examples:
658		1177
659	$res->resolve ("ruth.plan9.de", "a", sub {	1178	# full example, you can paste this into perl:
660	warn Dumper [@_];	1179	use Data::Dumper;
661	});	1180	use AnyEvent::DNS;
		1181	AnyEvent::DNS::resolver->resolve (
		1182	"google.com", "*", my $cv = AnyEvent->condvar);
		1183	warn Dumper [$cv->recv];
662		1184
		1185	# shortened result:
663	[	1186	# [
		1187	# [ 'google.com', 'soa', 'in', 'ns1.google.com', 'dns-admin.google.com',
		1188	# 2008052701, 7200, 1800, 1209600, 300 ],
664	[	1189	# [
665	'ruth.schmorp.de',	1190	# 'google.com', 'txt', 'in',
666	'a',	1191	# 'v=spf1 include:_netblocks.google.com ~all'
667	'in',	1192	# ],
668	'129.13.162.95'	1193	# [ 'google.com', 'a', 'in', '64.233.187.99' ],
		1194	# [ 'google.com', 'mx', 'in', 10, 'smtp2.google.com' ],
		1195	# [ 'google.com', 'ns', 'in', 'ns2.google.com' ],
669	]	1196	# ]
		1197
		1198	# resolve a records:
		1199	$res->resolve ("ruth.plan9.de", "a", sub { warn Dumper [@_] });
		1200
		1201	# result:
		1202	# [
		1203	# [ 'ruth.schmorp.de', 'a', 'in', '129.13.162.95' ]
670	]	1204	# ]
671		1205
		1206	# resolve any records, but return only a and aaaa records:
672	$res->resolve ("test1.laendle", "*",	1207	$res->resolve ("test1.laendle", "*",
673	accept => ["a", "aaaa"],	1208	accept => ["a", "aaaa"],
674	sub {	1209	sub {
675	warn Dumper [@_];	1210	warn Dumper [@_];
676	}	1211	}
677	);	1212	);
678		1213
679	[	1214	# result:
680	[	1215	# [
681	'test1.laendle',	1216	# [ 'test1.laendle', 'a', 'in', '10.0.0.255' ],
682	'a',	1217	# [ 'test1.laendle', 'aaaa', 'in', '3ffe:1900:4545:0002:0240:0000:0000:f7e1' ]
683	'in',
684	'10.0.0.255'
685	],
686	[
687	'test1.laendle',
688	'aaaa',
689	'in',
690	'3ffe:1900:4545:0002:0240:0000:0000:f7e1'
691	]	1218	# ]
692	]
693		1219
694	=cut	1220	=cut
695		1221
696	sub resolve($%) {	1222	sub resolve($%) {
697	my $cb = pop;	1223	my $cb = pop;
…		…
710	my %atype = $opt{accept}	1236	my %atype = $opt{accept}
711	? map +($_ => 1), @{ $opt{accept} }	1237	? map +($_ => 1), @{ $opt{accept} }
712	: ($qtype => 1);	1238	: ($qtype => 1);
713		1239
714	# advance in searchlist	1240	# advance in searchlist
715	my $do_search; $do_search = sub {	1241	my ($do_search, $do_req);
		1242
		1243	$do_search = sub {
716	@search	1244	@search
717	or return $cb->();	1245	or (undef $do_search), (undef $do_req), return $cb->();
718		1246
719	(my $name = "$qname." . shift @search) =~ s/\.$//;	1247	(my $name = lc "$qname." . shift @search) =~ s/\.$//;
720	my $depth = 2;	1248	my $depth = 10;
721		1249
722	# advance in cname-chain	1250	# advance in cname-chain
723	my $do_req; $do_req = sub {	1251	$do_req = sub {
724	$self->request ({	1252	$self->request ({
725	rd => 1,	1253	rd => 1,
726	qd => [[$name, $qtype, $class]],	1254	qd => [[$name, $qtype, $class]],
727	}, sub {	1255	}, sub {
728	my ($res) = @_	1256	my ($res) = @_
…		…
730		1258
731	my $cname;	1259	my $cname;
732		1260
733	while () {	1261	while () {
734	# results found?	1262	# results found?
735	my @rr = grep $_->[0] eq $name && ($atype{"*"} \|\| $atype{$_->[1]}), @{ $res->{an} };	1263	my @rr = grep $name eq lc $_->[0] && ($atype{"*"} \|\| $atype{$_->[1]}), @{ $res->{an} };
736		1264
737	return $cb->(@rr)	1265	(undef $do_search), (undef $do_req), return $cb->(@rr)
738	if @rr;	1266	if @rr;
739		1267
740	# see if there is a cname we can follow	1268	# see if there is a cname we can follow
741	my @rr = grep $_->[0] eq $name && $_->[1] eq "cname", @{ $res->{an} };	1269	my @rr = grep $name eq lc $_->[0] && $_->[1] eq "cname", @{ $res->{an} };
742		1270
743	if (@rr) {	1271	if (@rr) {
744	$depth--	1272	$depth--
745	or return $do_search->(); # cname chain too long	1273	or return $do_search->(); # cname chain too long
746		1274
…		…
763	};	1291	};
764		1292
765	$do_search->();	1293	$do_search->();
766	}	1294	}
767		1295
		1296	=item $resolver->wait_for_slot ($cb->($resolver))
		1297
		1298	Wait until a free request slot is available and call the callback with the
		1299	resolver object.
		1300
		1301	A request slot is used each time a request is actually sent to the
		1302	nameservers: There are never more than C<max_outstanding> of them.
		1303
		1304	Although you can submit more requests (they will simply be queued until
		1305	a request slot becomes available), sometimes, usually for rate-limiting
		1306	purposes, it is useful to instead wait for a slot before generating the
		1307	request (or simply to know when the request load is low enough so one can
		1308	submit requests again).
		1309
		1310	This is what this method does: The callback will be called when submitting
		1311	a DNS request will not result in that request being queued. The callback
		1312	may or may not generate any requests in response.
		1313
		1314	Note that the callback will only be invoked when the request queue is
		1315	empty, so this does not play well if somebody else keeps the request queue
		1316	full at all times.
		1317
		1318	=cut
		1319
		1320	sub wait_for_slot {
		1321	my ($self, $cb) = @_;
		1322
		1323	push @{ $self->{wait} }, $cb;
		1324	$self->_scheduler;
		1325	}
		1326
		1327	use AnyEvent::Socket (); # circular dependency, so do not import anything and do it at the end
		1328
768	1;	1329	1;
769		1330
770	=back	1331	=back
771		1332
772	=head1 AUTHOR	1333	=head1 AUTHOR
773		1334
774	Marc Lehmann <schmorp@schmorp.de>	1335	Marc Lehmann <schmorp@schmorp.de>
775	http://home.schmorp.de/	1336	http://home.schmorp.de/
776		1337
777	=cut	1338	=cut
778		1339

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Comparing AnyEvent/lib/AnyEvent/DNS.pm (file contents): Revision 1.2 by root, Fri May 23 02:59:32 2008 UTC vs. Revision 1.62 by root, Wed Jun 4 11:45:21 2008 UTC

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Comparing AnyEvent/lib/AnyEvent/DNS.pm (file contents):
Revision 1.2 by root, Fri May 23 02:59:32 2008 UTC vs.
Revision 1.62 by root, Wed Jun 4 11:45:21 2008 UTC