1 |
=head1 NAME |
2 |
|
3 |
AnyEvent::DNS - fully asynchronous DNS resolution |
4 |
|
5 |
=head1 SYNOPSIS |
6 |
|
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; |
13 |
|
14 |
=head1 DESCRIPTION |
15 |
|
16 |
This module offers both a number of DNS convenience functions as well |
17 |
as a fully asynchronous and high-performance pure-perl stub resolver. |
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 |
|
23 |
=head2 CONVENIENCE FUNCTIONS |
24 |
|
25 |
=over 4 |
26 |
|
27 |
=cut |
28 |
|
29 |
package AnyEvent::DNS; |
30 |
|
31 |
no warnings; |
32 |
use strict; |
33 |
|
34 |
use Carp (); |
35 |
use Socket qw(AF_INET SOCK_DGRAM SOCK_STREAM); |
36 |
|
37 |
use AnyEvent (); |
38 |
use AnyEvent::Util qw(AF_INET6); |
39 |
|
40 |
our $VERSION = 4.8; |
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($$) { |
155 |
my ($domain, $cb) = @_; |
156 |
|
157 |
resolver->resolve ($domain => "txt", sub { |
158 |
$cb->(map $_->[3], @_); |
159 |
}); |
160 |
} |
161 |
|
162 |
sub srv($$$$) { |
163 |
my ($service, $proto, $domain, $cb) = @_; |
164 |
|
165 |
# todo, ask for any and check glue records |
166 |
resolver->resolve ("_$service._$proto.$domain" => "srv", sub { |
167 |
my @res; |
168 |
|
169 |
# classify by priority |
170 |
my %pri; |
171 |
push @{ $pri{$_->[3]} }, [ @$_[3,4,5,6] ] |
172 |
for @_; |
173 |
|
174 |
# order by priority |
175 |
for my $pri (sort { $a <=> $b } keys %pri) { |
176 |
# order by weight |
177 |
my @rr = sort { $a->[1] <=> $b->[1] } @{ delete $pri{$pri} }; |
178 |
|
179 |
my $sum; $sum += $_->[1] for @rr; |
180 |
|
181 |
while (@rr) { |
182 |
my $w = int rand $sum + 1; |
183 |
for (0 .. $#rr) { |
184 |
if (($w -= $rr[$_][1]) <= 0) { |
185 |
$sum -= $rr[$_][1]; |
186 |
push @res, splice @rr, $_, 1, (); |
187 |
last; |
188 |
} |
189 |
} |
190 |
} |
191 |
} |
192 |
|
193 |
$cb->(@res); |
194 |
}); |
195 |
} |
196 |
|
197 |
sub ptr($$) { |
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 |
################################################################################# |
284 |
|
285 |
=back |
286 |
|
287 |
=head2 LOW-LEVEL DNS EN-/DECODING FUNCTIONS |
288 |
|
289 |
=over 4 |
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 |
|
298 |
=cut |
299 |
|
300 |
our $EDNS0 = $ENV{PERL_ANYEVENT_EDNS0}*1; # set to 1 to enable (partial) edns0 |
301 |
|
302 |
our %opcode_id = ( |
303 |
query => 0, |
304 |
iquery => 1, |
305 |
status => 2, |
306 |
notify => 4, |
307 |
update => 5, |
308 |
map +($_ => $_), 3, 6..15 |
309 |
); |
310 |
|
311 |
our %opcode_str = reverse %opcode_id; |
312 |
|
313 |
our %rcode_id = ( |
314 |
noerror => 0, |
315 |
formerr => 1, |
316 |
servfail => 2, |
317 |
nxdomain => 3, |
318 |
notimp => 4, |
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] |
332 |
map +($_ => $_), 11..15 |
333 |
); |
334 |
|
335 |
our %rcode_str = reverse %rcode_id; |
336 |
|
337 |
our %type_id = ( |
338 |
a => 1, |
339 |
ns => 2, |
340 |
md => 3, |
341 |
mf => 4, |
342 |
cname => 5, |
343 |
soa => 6, |
344 |
mb => 7, |
345 |
mg => 8, |
346 |
mr => 9, |
347 |
null => 10, |
348 |
wks => 11, |
349 |
ptr => 12, |
350 |
hinfo => 13, |
351 |
minfo => 14, |
352 |
mx => 15, |
353 |
txt => 16, |
354 |
aaaa => 28, |
355 |
srv => 33, |
356 |
naptr => 35, # rfc2915 |
357 |
dname => 39, # rfc2672 |
358 |
opt => 41, |
359 |
spf => 99, |
360 |
tkey => 249, |
361 |
tsig => 250, |
362 |
ixfr => 251, |
363 |
axfr => 252, |
364 |
mailb => 253, |
365 |
"*" => 255, |
366 |
); |
367 |
|
368 |
our %type_str = reverse %type_id; |
369 |
|
370 |
our %class_id = ( |
371 |
in => 1, |
372 |
ch => 3, |
373 |
hs => 4, |
374 |
none => 254, |
375 |
"*" => 255, |
376 |
); |
377 |
|
378 |
our %class_str = reverse %class_id; |
379 |
|
380 |
sub _enc_name($) { |
381 |
pack "(C/a*)*", (split /\./, shift), "" |
382 |
} |
383 |
|
384 |
sub _enc_qd() { |
385 |
(_enc_name $_->[0]) . pack "nn", |
386 |
($_->[1] > 0 ? $_->[1] : $type_id {$_->[1]}), |
387 |
($_->[2] > 0 ? $_->[2] : $class_id{$_->[2] || "in"}) |
388 |
} |
389 |
|
390 |
sub _enc_rr() { |
391 |
die "encoding of resource records is not supported"; |
392 |
} |
393 |
|
394 |
=item $pkt = AnyEvent::DNS::dns_pack $dns |
395 |
|
396 |
Packs a perl data structure into a DNS packet. Reading RFC 1035 is strongly |
397 |
recommended, then everything will be totally clear. Or maybe not. |
398 |
|
399 |
Resource records are not yet encodable. |
400 |
|
401 |
Examples: |
402 |
|
403 |
# very simple request, using lots of default values: |
404 |
{ rd => 1, qd => [ [ "host.domain", "a"] ] } |
405 |
|
406 |
# more complex example, showing how flags etc. are named: |
407 |
|
408 |
{ |
409 |
id => 10000, |
410 |
op => "query", |
411 |
rc => "nxdomain", |
412 |
|
413 |
# flags |
414 |
qr => 1, |
415 |
aa => 0, |
416 |
tc => 0, |
417 |
rd => 0, |
418 |
ra => 0, |
419 |
ad => 0, |
420 |
cd => 0, |
421 |
|
422 |
qd => [@rr], # query section |
423 |
an => [@rr], # answer section |
424 |
ns => [@rr], # authority section |
425 |
ar => [@rr], # additional records section |
426 |
} |
427 |
|
428 |
=cut |
429 |
|
430 |
sub dns_pack($) { |
431 |
my ($req) = @_; |
432 |
|
433 |
pack "nn nnnn a* a* a* a* a*", |
434 |
$req->{id}, |
435 |
|
436 |
! !$req->{qr} * 0x8000 |
437 |
+ $opcode_id{$req->{op}} * 0x0800 |
438 |
+ ! !$req->{aa} * 0x0400 |
439 |
+ ! !$req->{tc} * 0x0200 |
440 |
+ ! !$req->{rd} * 0x0100 |
441 |
+ ! !$req->{ra} * 0x0080 |
442 |
+ ! !$req->{ad} * 0x0020 |
443 |
+ ! !$req->{cd} * 0x0010 |
444 |
+ $rcode_id{$req->{rc}} * 0x0001, |
445 |
|
446 |
scalar @{ $req->{qd} || [] }, |
447 |
scalar @{ $req->{an} || [] }, |
448 |
scalar @{ $req->{ns} || [] }, |
449 |
$EDNS0 + scalar @{ $req->{ar} || [] }, # EDNS0 option included here |
450 |
|
451 |
(join "", map _enc_qd, @{ $req->{qd} || [] }), |
452 |
(join "", map _enc_rr, @{ $req->{an} || [] }), |
453 |
(join "", map _enc_rr, @{ $req->{ns} || [] }), |
454 |
(join "", map _enc_rr, @{ $req->{ar} || [] }), |
455 |
|
456 |
($EDNS0 ? pack "C nnNn", 0, 41, MAX_PKT, 0, 0 : "") # EDNS0 option |
457 |
} |
458 |
|
459 |
our $ofs; |
460 |
our $pkt; |
461 |
|
462 |
# bitches |
463 |
sub _dec_name { |
464 |
my @res; |
465 |
my $redir; |
466 |
my $ptr = $ofs; |
467 |
my $cnt; |
468 |
|
469 |
while () { |
470 |
return undef if ++$cnt >= 256; # to avoid DoS attacks |
471 |
|
472 |
my $len = ord substr $pkt, $ptr++, 1; |
473 |
|
474 |
if ($len >= 0xc0) { |
475 |
$ptr++; |
476 |
$ofs = $ptr if $ptr > $ofs; |
477 |
$ptr = (unpack "n", substr $pkt, $ptr - 2, 2) & 0x3fff; |
478 |
} elsif ($len) { |
479 |
push @res, substr $pkt, $ptr, $len; |
480 |
$ptr += $len; |
481 |
} else { |
482 |
$ofs = $ptr if $ptr > $ofs; |
483 |
return join ".", @res; |
484 |
} |
485 |
} |
486 |
} |
487 |
|
488 |
sub _dec_qd { |
489 |
my $qname = _dec_name; |
490 |
my ($qt, $qc) = unpack "nn", substr $pkt, $ofs; $ofs += 4; |
491 |
[$qname, $type_str{$qt} || $qt, $class_str{$qc} || $qc] |
492 |
} |
493 |
|
494 |
our %dec_rr = ( |
495 |
1 => sub { join ".", unpack "C4", $_ }, # a |
496 |
2 => sub { local $ofs = $ofs - length; _dec_name }, # ns |
497 |
5 => sub { local $ofs = $ofs - length; _dec_name }, # cname |
498 |
6 => sub { |
499 |
local $ofs = $ofs - length; |
500 |
my $mname = _dec_name; |
501 |
my $rname = _dec_name; |
502 |
($mname, $rname, unpack "NNNNN", substr $pkt, $ofs) |
503 |
}, # soa |
504 |
11 => sub { ((join ".", unpack "C4", $_), unpack "C a*", substr $_, 4) }, # wks |
505 |
12 => sub { local $ofs = $ofs - length; _dec_name }, # ptr |
506 |
13 => sub { unpack "C/a* C/a*", $_ }, # hinfo |
507 |
15 => sub { local $ofs = $ofs + 2 - length; ((unpack "n", $_), _dec_name) }, # mx |
508 |
16 => sub { unpack "(C/a*)*", $_ }, # txt |
509 |
28 => sub { AnyEvent::Socket::format_ipv6 ($_) }, # aaaa |
510 |
33 => sub { local $ofs = $ofs + 6 - length; ((unpack "nnn", $_), _dec_name) }, # srv |
511 |
35 => sub { # naptr |
512 |
# requires perl 5.10, sorry |
513 |
my ($order, $preference, $flags, $service, $regexp, $offset) = unpack "nn C/a* C/a* C/a* .", $_; |
514 |
local $ofs = $ofs + $offset - length; |
515 |
($order, $preference, $flags, $service, $regexp, _dec_name) |
516 |
}, |
517 |
39 => sub { local $ofs = $ofs - length; _dec_name }, # dname |
518 |
99 => sub { unpack "(C/a*)*", $_ }, # spf |
519 |
); |
520 |
|
521 |
sub _dec_rr { |
522 |
my $name = _dec_name; |
523 |
|
524 |
my ($rt, $rc, $ttl, $rdlen) = unpack "nn N n", substr $pkt, $ofs; $ofs += 10; |
525 |
local $_ = substr $pkt, $ofs, $rdlen; $ofs += $rdlen; |
526 |
|
527 |
[ |
528 |
$name, |
529 |
$type_str{$rt} || $rt, |
530 |
$class_str{$rc} || $rc, |
531 |
($dec_rr{$rt} || sub { $_ })->(), |
532 |
] |
533 |
} |
534 |
|
535 |
=item $dns = AnyEvent::DNS::dns_unpack $pkt |
536 |
|
537 |
Unpacks a DNS packet into a perl data structure. |
538 |
|
539 |
Examples: |
540 |
|
541 |
# an unsuccessful reply |
542 |
{ |
543 |
'qd' => [ |
544 |
[ 'ruth.plan9.de.mach.uni-karlsruhe.de', '*', 'in' ] |
545 |
], |
546 |
'rc' => 'nxdomain', |
547 |
'ar' => [], |
548 |
'ns' => [ |
549 |
[ |
550 |
'uni-karlsruhe.de', |
551 |
'soa', |
552 |
'in', |
553 |
'netserv.rz.uni-karlsruhe.de', |
554 |
'hostmaster.rz.uni-karlsruhe.de', |
555 |
2008052201, 10800, 1800, 2592000, 86400 |
556 |
] |
557 |
], |
558 |
'tc' => '', |
559 |
'ra' => 1, |
560 |
'qr' => 1, |
561 |
'id' => 45915, |
562 |
'aa' => '', |
563 |
'an' => [], |
564 |
'rd' => 1, |
565 |
'op' => 'query' |
566 |
} |
567 |
|
568 |
# a successful reply |
569 |
|
570 |
{ |
571 |
'qd' => [ [ 'www.google.de', 'a', 'in' ] ], |
572 |
'rc' => 0, |
573 |
'ar' => [ |
574 |
[ 'a.l.google.com', 'a', 'in', '209.85.139.9' ], |
575 |
[ 'b.l.google.com', 'a', 'in', '64.233.179.9' ], |
576 |
[ 'c.l.google.com', 'a', 'in', '64.233.161.9' ], |
577 |
], |
578 |
'ns' => [ |
579 |
[ 'l.google.com', 'ns', 'in', 'a.l.google.com' ], |
580 |
[ 'l.google.com', 'ns', 'in', 'b.l.google.com' ], |
581 |
], |
582 |
'tc' => '', |
583 |
'ra' => 1, |
584 |
'qr' => 1, |
585 |
'id' => 64265, |
586 |
'aa' => '', |
587 |
'an' => [ |
588 |
[ 'www.google.de', 'cname', 'in', 'www.google.com' ], |
589 |
[ 'www.google.com', 'cname', 'in', 'www.l.google.com' ], |
590 |
[ 'www.l.google.com', 'a', 'in', '66.249.93.104' ], |
591 |
[ 'www.l.google.com', 'a', 'in', '66.249.93.147' ], |
592 |
], |
593 |
'rd' => 1, |
594 |
'op' => 0 |
595 |
} |
596 |
|
597 |
=cut |
598 |
|
599 |
sub dns_unpack($) { |
600 |
local $pkt = shift; |
601 |
my ($id, $flags, $qd, $an, $ns, $ar) |
602 |
= unpack "nn nnnn A*", $pkt; |
603 |
|
604 |
local $ofs = 6 * 2; |
605 |
|
606 |
{ |
607 |
id => $id, |
608 |
qr => ! ! ($flags & 0x8000), |
609 |
aa => ! ! ($flags & 0x0400), |
610 |
tc => ! ! ($flags & 0x0200), |
611 |
rd => ! ! ($flags & 0x0100), |
612 |
ra => ! ! ($flags & 0x0080), |
613 |
ad => ! ! ($flags & 0x0020), |
614 |
cd => ! ! ($flags & 0x0010), |
615 |
op => $opcode_str{($flags & 0x001e) >> 11}, |
616 |
rc => $rcode_str{($flags & 0x000f)}, |
617 |
|
618 |
qd => [map _dec_qd, 1 .. $qd], |
619 |
an => [map _dec_rr, 1 .. $an], |
620 |
ns => [map _dec_rr, 1 .. $ns], |
621 |
ar => [map _dec_rr, 1 .. $ar], |
622 |
} |
623 |
} |
624 |
|
625 |
############################################################################# |
626 |
|
627 |
=back |
628 |
|
629 |
=head2 THE AnyEvent::DNS RESOLVER CLASS |
630 |
|
631 |
This is the class which does the actual protocol work. |
632 |
|
633 |
=over 4 |
634 |
|
635 |
=cut |
636 |
|
637 |
use Carp (); |
638 |
use Scalar::Util (); |
639 |
use Socket (); |
640 |
|
641 |
our $NOW; |
642 |
|
643 |
=item AnyEvent::DNS::resolver |
644 |
|
645 |
This function creates and returns a resolver that is ready to use and |
646 |
should mimic the default resolver for your system as good as possible. |
647 |
|
648 |
It only ever creates one resolver and returns this one on subsequent |
649 |
calls. |
650 |
|
651 |
Unless you have special needs, prefer this function over creating your own |
652 |
resolver object. |
653 |
|
654 |
The resolver is created with the following parameters: |
655 |
|
656 |
untaint enabled |
657 |
max_outstanding $ENV{PERL_ANYEVENT_MAX_OUTSTANDING_DNS} |
658 |
|
659 |
C<os_config> will be used for OS-specific configuration, unless |
660 |
C<$ENV{PERL_ANYEVENT_RESOLV_CONF}> is specified, in which case that file |
661 |
gets parsed. |
662 |
|
663 |
=cut |
664 |
|
665 |
our $RESOLVER; |
666 |
|
667 |
sub resolver() { |
668 |
$RESOLVER || do { |
669 |
$RESOLVER = new AnyEvent::DNS |
670 |
untaint => 1, |
671 |
exists $ENV{PERL_ANYEVENT_MAX_OUTSTANDING_DNS} |
672 |
? (max_outstanding => $ENV{PERL_ANYEVENT_MAX_OUTSTANDING_DNS}*1 || 1) : (), |
673 |
; |
674 |
|
675 |
exists $ENV{PERL_ANYEVENT_RESOLV_CONF} |
676 |
? length $ENV{PERL_ANYEVENT_RESOLV_CONF} && $RESOLVER->_parse_resolv_conf_file ($ENV{PERL_ANYEVENT_RESOLV_CONF}) |
677 |
: $RESOLVER->os_config; |
678 |
|
679 |
$RESOLVER |
680 |
} |
681 |
} |
682 |
|
683 |
=item $resolver = new AnyEvent::DNS key => value... |
684 |
|
685 |
Creates and returns a new resolver. |
686 |
|
687 |
The following options are supported: |
688 |
|
689 |
=over 4 |
690 |
|
691 |
=item server => [...] |
692 |
|
693 |
A list of server addresses (default: C<v127.0.0.1>) in network format |
694 |
(i.e. as returned by C<AnyEvent::Socket::parse_address> - both IPv4 and |
695 |
IPv6 are supported). |
696 |
|
697 |
=item timeout => [...] |
698 |
|
699 |
A list of timeouts to use (also determines the number of retries). To make |
700 |
three retries with individual time-outs of 2, 5 and 5 seconds, use C<[2, |
701 |
5, 5]>, which is also the default. |
702 |
|
703 |
=item search => [...] |
704 |
|
705 |
The default search list of suffixes to append to a domain name (default: none). |
706 |
|
707 |
=item ndots => $integer |
708 |
|
709 |
The number of dots (default: C<1>) that a name must have so that the resolver |
710 |
tries to resolve the name without any suffixes first. |
711 |
|
712 |
=item max_outstanding => $integer |
713 |
|
714 |
Most name servers do not handle many parallel requests very well. This |
715 |
option limits the number of outstanding requests to C<$integer> |
716 |
(default: C<10>), that means if you request more than this many requests, |
717 |
then the additional requests will be queued until some other requests have |
718 |
been resolved. |
719 |
|
720 |
=item reuse => $seconds |
721 |
|
722 |
The number of seconds (default: C<300>) that a query id cannot be re-used |
723 |
after a timeout. If there was no time-out then query ids can be reused |
724 |
immediately. |
725 |
|
726 |
=item untaint => $boolean |
727 |
|
728 |
When true, then the resolver will automatically untaint results, and might |
729 |
also ignore certain environment variables. |
730 |
|
731 |
=back |
732 |
|
733 |
=cut |
734 |
|
735 |
sub new { |
736 |
my ($class, %arg) = @_; |
737 |
|
738 |
my $self = bless { |
739 |
server => [], |
740 |
timeout => [2, 5, 5], |
741 |
search => [], |
742 |
ndots => 1, |
743 |
max_outstanding => 10, |
744 |
reuse => 300, |
745 |
%arg, |
746 |
reuse_q => [], |
747 |
}, $class; |
748 |
|
749 |
# search should default to gethostname's domain |
750 |
# but perl lacks a good posix module |
751 |
|
752 |
# try to create an ipv4 and an ipv6 socket |
753 |
# only fail when we cannot create either |
754 |
my $got_socket; |
755 |
|
756 |
Scalar::Util::weaken (my $wself = $self); |
757 |
|
758 |
if (socket my $fh4, AF_INET , &Socket::SOCK_DGRAM, 0) { |
759 |
++$got_socket; |
760 |
|
761 |
AnyEvent::Util::fh_nonblocking $fh4, 1; |
762 |
$self->{fh4} = $fh4; |
763 |
$self->{rw4} = AnyEvent->io (fh => $fh4, poll => "r", cb => sub { |
764 |
if (my $peer = recv $fh4, my $pkt, MAX_PKT, 0) { |
765 |
$wself->_recv ($pkt, $peer); |
766 |
} |
767 |
}); |
768 |
} |
769 |
|
770 |
if (AF_INET6 && socket my $fh6, AF_INET6, &Socket::SOCK_DGRAM, 0) { |
771 |
++$got_socket; |
772 |
|
773 |
$self->{fh6} = $fh6; |
774 |
AnyEvent::Util::fh_nonblocking $fh6, 1; |
775 |
$self->{rw6} = AnyEvent->io (fh => $fh6, poll => "r", cb => sub { |
776 |
if (my $peer = recv $fh6, my $pkt, MAX_PKT, 0) { |
777 |
$wself->_recv ($pkt, $peer); |
778 |
} |
779 |
}); |
780 |
} |
781 |
|
782 |
$got_socket |
783 |
or Carp::croak "unable to create either an IPv4 or an IPv6 socket"; |
784 |
|
785 |
$self->_compile; |
786 |
|
787 |
$self |
788 |
} |
789 |
|
790 |
=item $resolver->parse_resolv_conf ($string) |
791 |
|
792 |
Parses the given string as if it were a F<resolv.conf> file. The following |
793 |
directives are supported (but not necessarily implemented). |
794 |
|
795 |
C<#>-style comments, C<nameserver>, C<domain>, C<search>, C<sortlist>, |
796 |
C<options> (C<timeout>, C<attempts>, C<ndots>). |
797 |
|
798 |
Everything else is silently ignored. |
799 |
|
800 |
=cut |
801 |
|
802 |
sub parse_resolv_conf { |
803 |
my ($self, $resolvconf) = @_; |
804 |
|
805 |
$self->{server} = []; |
806 |
$self->{search} = []; |
807 |
|
808 |
my $attempts; |
809 |
|
810 |
for (split /\n/, $resolvconf) { |
811 |
if (/^\s*#/) { |
812 |
# comment |
813 |
} elsif (/^\s*nameserver\s+(\S+)\s*$/i) { |
814 |
my $ip = $1; |
815 |
if (my $ipn = AnyEvent::Socket::parse_address ($ip)) { |
816 |
push @{ $self->{server} }, $ipn; |
817 |
} else { |
818 |
warn "nameserver $ip invalid and ignored\n"; |
819 |
} |
820 |
} elsif (/^\s*domain\s+(\S*)\s+$/i) { |
821 |
$self->{search} = [$1]; |
822 |
} elsif (/^\s*search\s+(.*?)\s*$/i) { |
823 |
$self->{search} = [split /\s+/, $1]; |
824 |
} elsif (/^\s*sortlist\s+(.*?)\s*$/i) { |
825 |
# ignored, NYI |
826 |
} elsif (/^\s*options\s+(.*?)\s*$/i) { |
827 |
for (split /\s+/, $1) { |
828 |
if (/^timeout:(\d+)$/) { |
829 |
$self->{timeout} = [$1]; |
830 |
} elsif (/^attempts:(\d+)$/) { |
831 |
$attempts = $1; |
832 |
} elsif (/^ndots:(\d+)$/) { |
833 |
$self->{ndots} = $1; |
834 |
} else { |
835 |
# debug, rotate, no-check-names, inet6 |
836 |
} |
837 |
} |
838 |
} |
839 |
} |
840 |
|
841 |
$self->{timeout} = [($self->{timeout}[0]) x $attempts] |
842 |
if $attempts; |
843 |
|
844 |
$self->_compile; |
845 |
} |
846 |
|
847 |
sub _parse_resolv_conf_file { |
848 |
my ($self, $resolv_conf) = @_; |
849 |
|
850 |
open my $fh, "<:perlio", $resolv_conf |
851 |
or Carp::croak "$resolv_conf: $!"; |
852 |
|
853 |
local $/; |
854 |
$self->parse_resolv_conf (<$fh>); |
855 |
} |
856 |
|
857 |
=item $resolver->os_config |
858 |
|
859 |
Tries so load and parse F</etc/resolv.conf> on portable operating |
860 |
systems. Tries various egregious hacks on windows to force the DNS servers |
861 |
and searchlist out of the system. |
862 |
|
863 |
=cut |
864 |
|
865 |
sub os_config { |
866 |
my ($self) = @_; |
867 |
|
868 |
$self->{server} = []; |
869 |
$self->{search} = []; |
870 |
|
871 |
if ((AnyEvent::WIN32 || $^O =~ /cygwin/i)) { |
872 |
no strict 'refs'; |
873 |
|
874 |
# there are many options to find the current nameservers etc. on windows |
875 |
# all of them don't work consistently: |
876 |
# - the registry thing needs separate code on win32 native vs. cygwin |
877 |
# - the registry layout differs between windows versions |
878 |
# - calling windows api functions doesn't work on cygwin |
879 |
# - ipconfig uses locale-specific messages |
880 |
|
881 |
# we use ipconfig parsing because, despite all its brokenness, |
882 |
# it seems most stable in practise. |
883 |
# for good measure, we append a fallback nameserver to our list. |
884 |
|
885 |
if (open my $fh, "ipconfig /all |") { |
886 |
# parsing strategy: we go through the output and look for |
887 |
# :-lines with DNS in them. everything in those is regarded as |
888 |
# either a nameserver (if it parses as an ip address), or a suffix |
889 |
# (all else). |
890 |
|
891 |
my $dns; |
892 |
while (<$fh>) { |
893 |
if (s/^\s.*\bdns\b.*://i) { |
894 |
$dns = 1; |
895 |
} elsif (/^\S/ || /^\s[^:]{16,}: /) { |
896 |
$dns = 0; |
897 |
} |
898 |
if ($dns && /^\s*(\S+)\s*$/) { |
899 |
my $s = $1; |
900 |
$s =~ s/%\d+(?!\S)//; # get rid of ipv6 scope id |
901 |
if (my $ipn = AnyEvent::Socket::parse_address ($s)) { |
902 |
push @{ $self->{server} }, $ipn; |
903 |
} else { |
904 |
push @{ $self->{search} }, $s; |
905 |
} |
906 |
} |
907 |
} |
908 |
|
909 |
# always add one fallback server |
910 |
push @{ $self->{server} }, $DNS_FALLBACK[rand @DNS_FALLBACK]; |
911 |
|
912 |
$self->_compile; |
913 |
} |
914 |
} else { |
915 |
# try resolv.conf everywhere else |
916 |
|
917 |
$self->_parse_resolv_conf_file ("/etc/resolv.conf") |
918 |
if -e "/etc/resolv.conf"; |
919 |
} |
920 |
} |
921 |
|
922 |
=item $resolver->timeout ($timeout, ...) |
923 |
|
924 |
Sets the timeout values. See the C<timeout> constructor argument (and note |
925 |
that this method uses the values itself, not an array-reference). |
926 |
|
927 |
=cut |
928 |
|
929 |
sub timeout { |
930 |
my ($self, @timeout) = @_; |
931 |
|
932 |
$self->{timeout} = \@timeout; |
933 |
$self->_compile; |
934 |
} |
935 |
|
936 |
=item $resolver->max_outstanding ($nrequests) |
937 |
|
938 |
Sets the maximum number of outstanding requests to C<$nrequests>. See the |
939 |
C<max_outstanding> constructor argument. |
940 |
|
941 |
=cut |
942 |
|
943 |
sub max_outstanding { |
944 |
my ($self, $max) = @_; |
945 |
|
946 |
$self->{max_outstanding} = $max; |
947 |
$self->_scheduler; |
948 |
} |
949 |
|
950 |
sub _compile { |
951 |
my $self = shift; |
952 |
|
953 |
my %search; $self->{search} = [grep 0 < length, grep !$search{$_}++, @{ $self->{search} }]; |
954 |
my %server; $self->{server} = [grep 0 < length, grep !$server{$_}++, @{ $self->{server} }]; |
955 |
|
956 |
unless (@{ $self->{server} }) { |
957 |
# use 127.0.0.1 by default, and one opendns nameserver as fallback |
958 |
$self->{server} = [v127.0.0.1, $DNS_FALLBACK[rand @DNS_FALLBACK]]; |
959 |
} |
960 |
|
961 |
my @retry; |
962 |
|
963 |
for my $timeout (@{ $self->{timeout} }) { |
964 |
for my $server (@{ $self->{server} }) { |
965 |
push @retry, [$server, $timeout]; |
966 |
} |
967 |
} |
968 |
|
969 |
$self->{retry} = \@retry; |
970 |
} |
971 |
|
972 |
sub _feed { |
973 |
my ($self, $res) = @_; |
974 |
|
975 |
($res) = $res =~ /^(.*)$/s |
976 |
if AnyEvent::TAINT && $self->{untaint}; |
977 |
|
978 |
$res = dns_unpack $res |
979 |
or return; |
980 |
|
981 |
my $id = $self->{id}{$res->{id}}; |
982 |
|
983 |
return unless ref $id; |
984 |
|
985 |
$NOW = time; |
986 |
$id->[1]->($res); |
987 |
} |
988 |
|
989 |
sub _recv { |
990 |
my ($self, $pkt, $peer) = @_; |
991 |
|
992 |
# we ignore errors (often one gets port unreachable, but there is |
993 |
# no good way to take advantage of that. |
994 |
|
995 |
my ($port, $host) = AnyEvent::Socket::unpack_sockaddr ($peer); |
996 |
|
997 |
return unless $port == 53 && grep $_ eq $host, @{ $self->{server} }; |
998 |
|
999 |
$self->_feed ($pkt); |
1000 |
} |
1001 |
|
1002 |
sub _free_id { |
1003 |
my ($self, $id, $timeout) = @_; |
1004 |
|
1005 |
if ($timeout) { |
1006 |
# we need to block the id for a while |
1007 |
$self->{id}{$id} = 1; |
1008 |
push @{ $self->{reuse_q} }, [$NOW + $self->{reuse}, $id]; |
1009 |
} else { |
1010 |
# we can quickly recycle the id |
1011 |
delete $self->{id}{$id}; |
1012 |
} |
1013 |
|
1014 |
--$self->{outstanding}; |
1015 |
$self->_scheduler; |
1016 |
} |
1017 |
|
1018 |
# execute a single request, involves sending it with timeouts to multiple servers |
1019 |
sub _exec { |
1020 |
my ($self, $req) = @_; |
1021 |
|
1022 |
my $retry; # of retries |
1023 |
my $do_retry; |
1024 |
|
1025 |
$do_retry = sub { |
1026 |
my $retry_cfg = $self->{retry}[$retry++] |
1027 |
or do { |
1028 |
# failure |
1029 |
$self->_free_id ($req->[2], $retry > 1); |
1030 |
undef $do_retry; return $req->[1]->(); |
1031 |
}; |
1032 |
|
1033 |
my ($server, $timeout) = @$retry_cfg; |
1034 |
|
1035 |
$self->{id}{$req->[2]} = [AnyEvent->timer (after => $timeout, cb => sub { |
1036 |
$NOW = time; |
1037 |
|
1038 |
# timeout, try next |
1039 |
&$do_retry if $do_retry; |
1040 |
}), sub { |
1041 |
my ($res) = @_; |
1042 |
|
1043 |
if ($res->{tc}) { |
1044 |
# success, but truncated, so use tcp |
1045 |
AnyEvent::Socket::tcp_connect (AnyEvent::Socket::format_address ($server), DOMAIN_PORT, sub { |
1046 |
return unless $do_retry; # some other request could have invalidated us already |
1047 |
|
1048 |
my ($fh) = @_ |
1049 |
or return &$do_retry; |
1050 |
|
1051 |
require AnyEvent::Handle; |
1052 |
|
1053 |
my $handle; $handle = new AnyEvent::Handle |
1054 |
fh => $fh, |
1055 |
timeout => $timeout, |
1056 |
on_error => sub { |
1057 |
undef $handle; |
1058 |
return unless $do_retry; # some other request could have invalidated us already |
1059 |
# failure, try next |
1060 |
&$do_retry; |
1061 |
}; |
1062 |
|
1063 |
$handle->push_write (pack "n/a", $req->[0]); |
1064 |
$handle->push_read (chunk => 2, sub { |
1065 |
$handle->unshift_read (chunk => (unpack "n", $_[1]), sub { |
1066 |
undef $handle; |
1067 |
$self->_feed ($_[1]); |
1068 |
}); |
1069 |
}); |
1070 |
|
1071 |
}, sub { $timeout }); |
1072 |
|
1073 |
} else { |
1074 |
# success |
1075 |
$self->_free_id ($req->[2], $retry > 1); |
1076 |
undef $do_retry; return $req->[1]->($res); |
1077 |
} |
1078 |
}]; |
1079 |
|
1080 |
my $sa = AnyEvent::Socket::pack_sockaddr (DOMAIN_PORT, $server); |
1081 |
|
1082 |
my $fh = AF_INET == Socket::sockaddr_family ($sa) |
1083 |
? $self->{fh4} : $self->{fh6} |
1084 |
or return &$do_retry; |
1085 |
|
1086 |
send $fh, $req->[0], 0, $sa; |
1087 |
}; |
1088 |
|
1089 |
&$do_retry; |
1090 |
} |
1091 |
|
1092 |
sub _scheduler { |
1093 |
my ($self) = @_; |
1094 |
|
1095 |
no strict 'refs'; |
1096 |
|
1097 |
$NOW = time; |
1098 |
|
1099 |
# first clear id reuse queue |
1100 |
delete $self->{id}{ (shift @{ $self->{reuse_q} })->[1] } |
1101 |
while @{ $self->{reuse_q} } && $self->{reuse_q}[0][0] <= $NOW; |
1102 |
|
1103 |
while ($self->{outstanding} < $self->{max_outstanding}) { |
1104 |
|
1105 |
if (@{ $self->{reuse_q} } >= 30000) { |
1106 |
# we ran out of ID's, wait a bit |
1107 |
$self->{reuse_to} ||= AnyEvent->timer (after => $self->{reuse_q}[0][0] - $NOW, cb => sub { |
1108 |
delete $self->{reuse_to}; |
1109 |
$self->_scheduler; |
1110 |
}); |
1111 |
last; |
1112 |
} |
1113 |
|
1114 |
if (my $req = shift @{ $self->{queue} }) { |
1115 |
# found a request in the queue, execute it |
1116 |
while () { |
1117 |
$req->[2] = int rand 65536; |
1118 |
last unless exists $self->{id}{$req->[2]}; |
1119 |
} |
1120 |
|
1121 |
++$self->{outstanding}; |
1122 |
$self->{id}{$req->[2]} = 1; |
1123 |
substr $req->[0], 0, 2, pack "n", $req->[2]; |
1124 |
|
1125 |
$self->_exec ($req); |
1126 |
|
1127 |
} elsif (my $cb = shift @{ $self->{wait} }) { |
1128 |
# found a wait_for_slot callback, call that one first |
1129 |
$cb->($self); |
1130 |
|
1131 |
} else { |
1132 |
# nothing to do, just exit |
1133 |
last; |
1134 |
} |
1135 |
} |
1136 |
} |
1137 |
|
1138 |
=item $resolver->request ($req, $cb->($res)) |
1139 |
|
1140 |
This is the main low-level workhorse for sending DNS requests. |
1141 |
|
1142 |
This function sends a single request (a hash-ref formated as specified |
1143 |
for C<dns_pack>) to the configured nameservers in turn until it gets a |
1144 |
response. It handles timeouts, retries and automatically falls back to |
1145 |
virtual circuit mode (TCP) when it receives a truncated reply. |
1146 |
|
1147 |
Calls the callback with the decoded response packet if a reply was |
1148 |
received, or no arguments in case none of the servers answered. |
1149 |
|
1150 |
=cut |
1151 |
|
1152 |
sub request($$) { |
1153 |
my ($self, $req, $cb) = @_; |
1154 |
|
1155 |
push @{ $self->{queue} }, [dns_pack $req, $cb]; |
1156 |
$self->_scheduler; |
1157 |
} |
1158 |
|
1159 |
=item $resolver->resolve ($qname, $qtype, %options, $cb->(@rr)) |
1160 |
|
1161 |
Queries the DNS for the given domain name C<$qname> of type C<$qtype>. |
1162 |
|
1163 |
A C<$qtype> is either a numerical query type (e.g. C<1> for A records) or |
1164 |
a lowercase name (you have to look at the source to see which aliases are |
1165 |
supported, but all types from RFC 1035, C<aaaa>, C<srv>, C<spf> and a few |
1166 |
more are known to this module). A C<$qtype> of "*" is supported and means |
1167 |
"any" record type. |
1168 |
|
1169 |
The callback will be invoked with a list of matching result records or |
1170 |
none on any error or if the name could not be found. |
1171 |
|
1172 |
CNAME chains (although illegal) are followed up to a length of 10. |
1173 |
|
1174 |
The callback will be invoked with arraryefs of the form C<[$name, $type, |
1175 |
$class, @data>], where C<$name> is the domain name, C<$type> a type string |
1176 |
or number, C<$class> a class name and @data is resource-record-dependent |
1177 |
data. For C<a> records, this will be the textual IPv4 addresses, for C<ns> |
1178 |
or C<cname> records this will be a domain name, for C<txt> records these |
1179 |
are all the strings and so on. |
1180 |
|
1181 |
All types mentioned in RFC 1035, C<aaaa>, C<srv>, C<naptr> and C<spf> are |
1182 |
decoded. All resource records not known to this module will have |
1183 |
the raw C<rdata> field as fourth entry. |
1184 |
|
1185 |
Note that this resolver is just a stub resolver: it requires a name server |
1186 |
supporting recursive queries, will not do any recursive queries itself and |
1187 |
is not secure when used against an untrusted name server. |
1188 |
|
1189 |
The following options are supported: |
1190 |
|
1191 |
=over 4 |
1192 |
|
1193 |
=item search => [$suffix...] |
1194 |
|
1195 |
Use the given search list (which might be empty), by appending each one |
1196 |
in turn to the C<$qname>. If this option is missing then the configured |
1197 |
C<ndots> and C<search> values define its value (depending on C<ndots>, the |
1198 |
empty suffix will be prepended or appended to that C<search> value). If |
1199 |
the C<$qname> ends in a dot, then the searchlist will be ignored. |
1200 |
|
1201 |
=item accept => [$type...] |
1202 |
|
1203 |
Lists the acceptable result types: only result types in this set will be |
1204 |
accepted and returned. The default includes the C<$qtype> and nothing |
1205 |
else. If this list includes C<cname>, then CNAME-chains will not be |
1206 |
followed (because you asked for the CNAME record). |
1207 |
|
1208 |
=item class => "class" |
1209 |
|
1210 |
Specify the query class ("in" for internet, "ch" for chaosnet and "hs" for |
1211 |
hesiod are the only ones making sense). The default is "in", of course. |
1212 |
|
1213 |
=back |
1214 |
|
1215 |
Examples: |
1216 |
|
1217 |
# full example, you can paste this into perl: |
1218 |
use Data::Dumper; |
1219 |
use AnyEvent::DNS; |
1220 |
AnyEvent::DNS::resolver->resolve ( |
1221 |
"google.com", "*", my $cv = AnyEvent->condvar); |
1222 |
warn Dumper [$cv->recv]; |
1223 |
|
1224 |
# shortened result: |
1225 |
# [ |
1226 |
# [ 'google.com', 'soa', 'in', 'ns1.google.com', 'dns-admin.google.com', |
1227 |
# 2008052701, 7200, 1800, 1209600, 300 ], |
1228 |
# [ |
1229 |
# 'google.com', 'txt', 'in', |
1230 |
# 'v=spf1 include:_netblocks.google.com ~all' |
1231 |
# ], |
1232 |
# [ 'google.com', 'a', 'in', '64.233.187.99' ], |
1233 |
# [ 'google.com', 'mx', 'in', 10, 'smtp2.google.com' ], |
1234 |
# [ 'google.com', 'ns', 'in', 'ns2.google.com' ], |
1235 |
# ] |
1236 |
|
1237 |
# resolve a records: |
1238 |
$res->resolve ("ruth.plan9.de", "a", sub { warn Dumper [@_] }); |
1239 |
|
1240 |
# result: |
1241 |
# [ |
1242 |
# [ 'ruth.schmorp.de', 'a', 'in', '129.13.162.95' ] |
1243 |
# ] |
1244 |
|
1245 |
# resolve any records, but return only a and aaaa records: |
1246 |
$res->resolve ("test1.laendle", "*", |
1247 |
accept => ["a", "aaaa"], |
1248 |
sub { |
1249 |
warn Dumper [@_]; |
1250 |
} |
1251 |
); |
1252 |
|
1253 |
# result: |
1254 |
# [ |
1255 |
# [ 'test1.laendle', 'a', 'in', '10.0.0.255' ], |
1256 |
# [ 'test1.laendle', 'aaaa', 'in', '3ffe:1900:4545:0002:0240:0000:0000:f7e1' ] |
1257 |
# ] |
1258 |
|
1259 |
=cut |
1260 |
|
1261 |
sub resolve($%) { |
1262 |
my $cb = pop; |
1263 |
my ($self, $qname, $qtype, %opt) = @_; |
1264 |
|
1265 |
my @search = $qname =~ s/\.$// |
1266 |
? "" |
1267 |
: $opt{search} |
1268 |
? @{ $opt{search} } |
1269 |
: ($qname =~ y/.//) >= $self->{ndots} |
1270 |
? ("", @{ $self->{search} }) |
1271 |
: (@{ $self->{search} }, ""); |
1272 |
|
1273 |
my $class = $opt{class} || "in"; |
1274 |
|
1275 |
my %atype = $opt{accept} |
1276 |
? map +($_ => 1), @{ $opt{accept} } |
1277 |
: ($qtype => 1); |
1278 |
|
1279 |
# advance in searchlist |
1280 |
my ($do_search, $do_req); |
1281 |
|
1282 |
$do_search = sub { |
1283 |
@search |
1284 |
or (undef $do_search), (undef $do_req), return $cb->(); |
1285 |
|
1286 |
(my $name = lc "$qname." . shift @search) =~ s/\.$//; |
1287 |
my $depth = 10; |
1288 |
|
1289 |
# advance in cname-chain |
1290 |
$do_req = sub { |
1291 |
$self->request ({ |
1292 |
rd => 1, |
1293 |
qd => [[$name, $qtype, $class]], |
1294 |
}, sub { |
1295 |
my ($res) = @_ |
1296 |
or return $do_search->(); |
1297 |
|
1298 |
my $cname; |
1299 |
|
1300 |
while () { |
1301 |
# results found? |
1302 |
my @rr = grep $name eq lc $_->[0] && ($atype{"*"} || $atype{$_->[1]}), @{ $res->{an} }; |
1303 |
|
1304 |
(undef $do_search), (undef $do_req), return $cb->(@rr) |
1305 |
if @rr; |
1306 |
|
1307 |
# see if there is a cname we can follow |
1308 |
my @rr = grep $name eq lc $_->[0] && $_->[1] eq "cname", @{ $res->{an} }; |
1309 |
|
1310 |
if (@rr) { |
1311 |
$depth-- |
1312 |
or return $do_search->(); # cname chain too long |
1313 |
|
1314 |
$cname = 1; |
1315 |
$name = lc $rr[0][3]; |
1316 |
|
1317 |
} elsif ($cname) { |
1318 |
# follow the cname |
1319 |
return $do_req->(); |
1320 |
|
1321 |
} else { |
1322 |
# no, not found anything |
1323 |
return $do_search->(); |
1324 |
} |
1325 |
} |
1326 |
}); |
1327 |
}; |
1328 |
|
1329 |
$do_req->(); |
1330 |
}; |
1331 |
|
1332 |
$do_search->(); |
1333 |
} |
1334 |
|
1335 |
=item $resolver->wait_for_slot ($cb->($resolver)) |
1336 |
|
1337 |
Wait until a free request slot is available and call the callback with the |
1338 |
resolver object. |
1339 |
|
1340 |
A request slot is used each time a request is actually sent to the |
1341 |
nameservers: There are never more than C<max_outstanding> of them. |
1342 |
|
1343 |
Although you can submit more requests (they will simply be queued until |
1344 |
a request slot becomes available), sometimes, usually for rate-limiting |
1345 |
purposes, it is useful to instead wait for a slot before generating the |
1346 |
request (or simply to know when the request load is low enough so one can |
1347 |
submit requests again). |
1348 |
|
1349 |
This is what this method does: The callback will be called when submitting |
1350 |
a DNS request will not result in that request being queued. The callback |
1351 |
may or may not generate any requests in response. |
1352 |
|
1353 |
Note that the callback will only be invoked when the request queue is |
1354 |
empty, so this does not play well if somebody else keeps the request queue |
1355 |
full at all times. |
1356 |
|
1357 |
=cut |
1358 |
|
1359 |
sub wait_for_slot { |
1360 |
my ($self, $cb) = @_; |
1361 |
|
1362 |
push @{ $self->{wait} }, $cb; |
1363 |
$self->_scheduler; |
1364 |
} |
1365 |
|
1366 |
use AnyEvent::Socket (); # circular dependency, so do not import anything and do it at the end |
1367 |
|
1368 |
1; |
1369 |
|
1370 |
=back |
1371 |
|
1372 |
=head1 AUTHOR |
1373 |
|
1374 |
Marc Lehmann <schmorp@schmorp.de> |
1375 |
http://home.schmorp.de/ |
1376 |
|
1377 |
=cut |
1378 |
|