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 UDP, optional EDNS0 support for up to |
20 |
4kiB datagrams and automatically falls back to virtual circuit mode for |
21 |
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 Socket qw(AF_INET SOCK_DGRAM SOCK_STREAM); |
35 |
|
36 |
use AnyEvent (); |
37 |
use AnyEvent::Handle (); |
38 |
use AnyEvent::Util qw(AF_INET6); |
39 |
|
40 |
our @DNS_FALLBACK = (v208.67.220.220, v208.67.222.222); |
41 |
|
42 |
=item AnyEvent::DNS::a $domain, $cb->(@addrs) |
43 |
|
44 |
Tries to resolve the given domain to IPv4 address(es). |
45 |
|
46 |
=item AnyEvent::DNS::aaaa $domain, $cb->(@addrs) |
47 |
|
48 |
Tries to resolve the given domain to IPv6 address(es). |
49 |
|
50 |
=item AnyEvent::DNS::mx $domain, $cb->(@hostnames) |
51 |
|
52 |
Tries to resolve the given domain into a sorted (lower preference value |
53 |
first) list of domain names. |
54 |
|
55 |
=item AnyEvent::DNS::ns $domain, $cb->(@hostnames) |
56 |
|
57 |
Tries to resolve the given domain name into a list of name servers. |
58 |
|
59 |
=item AnyEvent::DNS::txt $domain, $cb->(@hostnames) |
60 |
|
61 |
Tries to resolve the given domain name into a list of text records. |
62 |
|
63 |
=item AnyEvent::DNS::srv $service, $proto, $domain, $cb->(@srv_rr) |
64 |
|
65 |
Tries to resolve the given service, protocol and domain name into a list |
66 |
of service records. |
67 |
|
68 |
Each srv_rr is an array reference with the following contents: |
69 |
C<[$priority, $weight, $transport, $target]>. |
70 |
|
71 |
They will be sorted with lowest priority, highest weight first (TODO: |
72 |
should use the RFC algorithm to reorder same-priority records for weight). |
73 |
|
74 |
Example: |
75 |
|
76 |
AnyEvent::DNS::srv "sip", "udp", "schmorp.de", sub { ... |
77 |
# @_ = ( [10, 10, 5060, "sip1.schmorp.de" ] ) |
78 |
|
79 |
=item AnyEvent::DNS::ptr $ipv4_or_6, $cb->(@hostnames) |
80 |
|
81 |
Tries to reverse-resolve the given IPv4 or IPv6 address (in textual form) |
82 |
into it's hostname(s). |
83 |
|
84 |
Example: |
85 |
|
86 |
AnyEvent::DNS::ptr "2001:500:2f::f", sub { print shift }; |
87 |
# => f.root-servers.net |
88 |
|
89 |
=item AnyEvent::DNS::any $domain, $cb->(@rrs) |
90 |
|
91 |
Tries to resolve the given domain and passes all resource records found to |
92 |
the callback. |
93 |
|
94 |
=cut |
95 |
|
96 |
sub MAX_PKT() { 4096 } # max packet size we advertise and accept |
97 |
|
98 |
sub DOMAIN_PORT() { 53 } # if this changes drop me a note |
99 |
|
100 |
sub resolver; |
101 |
|
102 |
sub a($$) { |
103 |
my ($domain, $cb) = @_; |
104 |
|
105 |
resolver->resolve ($domain => "a", sub { |
106 |
$cb->(map $_->[3], @_); |
107 |
}); |
108 |
} |
109 |
|
110 |
sub aaaa($$) { |
111 |
my ($domain, $cb) = @_; |
112 |
|
113 |
resolver->resolve ($domain => "aaaa", sub { |
114 |
$cb->(map $_->[3], @_); |
115 |
}); |
116 |
} |
117 |
|
118 |
sub mx($$) { |
119 |
my ($domain, $cb) = @_; |
120 |
|
121 |
resolver->resolve ($domain => "mx", sub { |
122 |
$cb->(map $_->[4], sort { $a->[3] <=> $b->[3] } @_); |
123 |
}); |
124 |
} |
125 |
|
126 |
sub ns($$) { |
127 |
my ($domain, $cb) = @_; |
128 |
|
129 |
resolver->resolve ($domain => "ns", sub { |
130 |
$cb->(map $_->[3], @_); |
131 |
}); |
132 |
} |
133 |
|
134 |
sub txt($$) { |
135 |
my ($domain, $cb) = @_; |
136 |
|
137 |
resolver->resolve ($domain => "txt", sub { |
138 |
$cb->(map $_->[3], @_); |
139 |
}); |
140 |
} |
141 |
|
142 |
sub srv($$$$) { |
143 |
my ($service, $proto, $domain, $cb) = @_; |
144 |
|
145 |
# todo, ask for any and check glue records |
146 |
resolver->resolve ("_$service._$proto.$domain" => "srv", sub { |
147 |
$cb->(map [@$_[3,4,5,6]], sort { $a->[3] <=> $b->[3] || $b->[4] <=> $a->[4] } @_); |
148 |
}); |
149 |
} |
150 |
|
151 |
sub ptr($$) { |
152 |
my ($ip, $cb) = @_; |
153 |
|
154 |
$ip = AnyEvent::Socket::parse_address ($ip) |
155 |
or return $cb->(); |
156 |
|
157 |
my $af = AnyEvent::Socket::address_family ($ip); |
158 |
|
159 |
if ($af == AF_INET) { |
160 |
$ip = join ".", (reverse split /\./, $ip), "in-addr.arpa."; |
161 |
} elsif ($af == AF_INET6) { |
162 |
$ip = join ".", (reverse split //, unpack "H*", $ip), "ip6.arpa."; |
163 |
} else { |
164 |
return $cb->(); |
165 |
} |
166 |
|
167 |
resolver->resolve ($ip => "ptr", sub { |
168 |
$cb->(map $_->[3], @_); |
169 |
}); |
170 |
} |
171 |
|
172 |
sub any($$) { |
173 |
my ($domain, $cb) = @_; |
174 |
|
175 |
resolver->resolve ($domain => "*", $cb); |
176 |
} |
177 |
|
178 |
################################################################################# |
179 |
|
180 |
=back |
181 |
|
182 |
=head2 LOW-LEVEL DNS EN-/DECODING FUNCTIONS |
183 |
|
184 |
=over 4 |
185 |
|
186 |
=item $AnyEvent::DNS::EDNS0 |
187 |
|
188 |
This variable decides whether dns_pack automatically enables EDNS0 |
189 |
support. By default, this is disabled (C<0>), unless overridden by |
190 |
C<$ENV{PERL_ANYEVENT_EDNS0>), but when set to C<1>, AnyEvent::DNS will use |
191 |
EDNS0 in all requests. |
192 |
|
193 |
=cut |
194 |
|
195 |
our $EDNS0 = $ENV{PERL_ANYEVENT_EDNS0} * 1; # set to 1 to enable (partial) edns0 |
196 |
|
197 |
our %opcode_id = ( |
198 |
query => 0, |
199 |
iquery => 1, |
200 |
status => 2, |
201 |
notify => 4, |
202 |
update => 5, |
203 |
map +($_ => $_), 3, 6..15 |
204 |
); |
205 |
|
206 |
our %opcode_str = reverse %opcode_id; |
207 |
|
208 |
our %rcode_id = ( |
209 |
noerror => 0, |
210 |
formerr => 1, |
211 |
servfail => 2, |
212 |
nxdomain => 3, |
213 |
notimp => 4, |
214 |
refused => 5, |
215 |
yxdomain => 6, # Name Exists when it should not [RFC 2136] |
216 |
yxrrset => 7, # RR Set Exists when it should not [RFC 2136] |
217 |
nxrrset => 8, # RR Set that should exist does not [RFC 2136] |
218 |
notauth => 9, # Server Not Authoritative for zone [RFC 2136] |
219 |
notzone => 10, # Name not contained in zone [RFC 2136] |
220 |
# EDNS0 16 BADVERS Bad OPT Version [RFC 2671] |
221 |
# EDNS0 16 BADSIG TSIG Signature Failure [RFC 2845] |
222 |
# EDNS0 17 BADKEY Key not recognized [RFC 2845] |
223 |
# EDNS0 18 BADTIME Signature out of time window [RFC 2845] |
224 |
# EDNS0 19 BADMODE Bad TKEY Mode [RFC 2930] |
225 |
# EDNS0 20 BADNAME Duplicate key name [RFC 2930] |
226 |
# EDNS0 21 BADALG Algorithm not supported [RFC 2930] |
227 |
map +($_ => $_), 11..15 |
228 |
); |
229 |
|
230 |
our %rcode_str = reverse %rcode_id; |
231 |
|
232 |
our %type_id = ( |
233 |
a => 1, |
234 |
ns => 2, |
235 |
md => 3, |
236 |
mf => 4, |
237 |
cname => 5, |
238 |
soa => 6, |
239 |
mb => 7, |
240 |
mg => 8, |
241 |
mr => 9, |
242 |
null => 10, |
243 |
wks => 11, |
244 |
ptr => 12, |
245 |
hinfo => 13, |
246 |
minfo => 14, |
247 |
mx => 15, |
248 |
txt => 16, |
249 |
aaaa => 28, |
250 |
srv => 33, |
251 |
opt => 41, |
252 |
spf => 99, |
253 |
tkey => 249, |
254 |
tsig => 250, |
255 |
ixfr => 251, |
256 |
axfr => 252, |
257 |
mailb => 253, |
258 |
"*" => 255, |
259 |
); |
260 |
|
261 |
our %type_str = reverse %type_id; |
262 |
|
263 |
our %class_id = ( |
264 |
in => 1, |
265 |
ch => 3, |
266 |
hs => 4, |
267 |
none => 254, |
268 |
"*" => 255, |
269 |
); |
270 |
|
271 |
our %class_str = reverse %class_id; |
272 |
|
273 |
# names MUST have a trailing dot |
274 |
sub _enc_name($) { |
275 |
pack "(C/a*)*", (split /\./, shift), "" |
276 |
} |
277 |
|
278 |
sub _enc_qd() { |
279 |
(_enc_name $_->[0]) . pack "nn", |
280 |
($_->[1] > 0 ? $_->[1] : $type_id {$_->[1]}), |
281 |
($_->[2] > 0 ? $_->[2] : $class_id{$_->[2] || "in"}) |
282 |
} |
283 |
|
284 |
sub _enc_rr() { |
285 |
die "encoding of resource records is not supported"; |
286 |
} |
287 |
|
288 |
=item $pkt = AnyEvent::DNS::dns_pack $dns |
289 |
|
290 |
Packs a perl data structure into a DNS packet. Reading RFC1034 is strongly |
291 |
recommended, then everything will be totally clear. Or maybe not. |
292 |
|
293 |
Resource records are not yet encodable. |
294 |
|
295 |
Examples: |
296 |
|
297 |
# very simple request, using lots of default values: |
298 |
{ rd => 1, qd => [ [ "host.domain", "a"] ] } |
299 |
|
300 |
# more complex example, showing how flags etc. are named: |
301 |
|
302 |
{ |
303 |
id => 10000, |
304 |
op => "query", |
305 |
rc => "nxdomain", |
306 |
|
307 |
# flags |
308 |
qr => 1, |
309 |
aa => 0, |
310 |
tc => 0, |
311 |
rd => 0, |
312 |
ra => 0, |
313 |
ad => 0, |
314 |
cd => 0, |
315 |
|
316 |
qd => [@rr], # query section |
317 |
an => [@rr], # answer section |
318 |
ns => [@rr], # authority section |
319 |
ar => [@rr], # additional records section |
320 |
} |
321 |
|
322 |
=cut |
323 |
|
324 |
sub dns_pack($) { |
325 |
my ($req) = @_; |
326 |
|
327 |
pack "nn nnnn a* a* a* a* a*", |
328 |
$req->{id}, |
329 |
|
330 |
! !$req->{qr} * 0x8000 |
331 |
+ $opcode_id{$req->{op}} * 0x0800 |
332 |
+ ! !$req->{aa} * 0x0400 |
333 |
+ ! !$req->{tc} * 0x0200 |
334 |
+ ! !$req->{rd} * 0x0100 |
335 |
+ ! !$req->{ra} * 0x0080 |
336 |
+ ! !$req->{ad} * 0x0020 |
337 |
+ ! !$req->{cd} * 0x0010 |
338 |
+ $rcode_id{$req->{rc}} * 0x0001, |
339 |
|
340 |
scalar @{ $req->{qd} || [] }, |
341 |
scalar @{ $req->{an} || [] }, |
342 |
scalar @{ $req->{ns} || [] }, |
343 |
$EDNS0 + scalar @{ $req->{ar} || [] }, # include EDNS0 option here |
344 |
|
345 |
(join "", map _enc_qd, @{ $req->{qd} || [] }), |
346 |
(join "", map _enc_rr, @{ $req->{an} || [] }), |
347 |
(join "", map _enc_rr, @{ $req->{ns} || [] }), |
348 |
(join "", map _enc_rr, @{ $req->{ar} || [] }), |
349 |
|
350 |
($EDNS0 ? pack "C nnNn", 0, 41, MAX_PKT, 0, 0 : "") # EDNS0, 4kiB udp payload size |
351 |
} |
352 |
|
353 |
our $ofs; |
354 |
our $pkt; |
355 |
|
356 |
# bitches |
357 |
sub _dec_name { |
358 |
my @res; |
359 |
my $redir; |
360 |
my $ptr = $ofs; |
361 |
my $cnt; |
362 |
|
363 |
while () { |
364 |
return undef if ++$cnt >= 256; # to avoid DoS attacks |
365 |
|
366 |
my $len = ord substr $pkt, $ptr++, 1; |
367 |
|
368 |
if ($len >= 0xc0) { |
369 |
$ptr++; |
370 |
$ofs = $ptr if $ptr > $ofs; |
371 |
$ptr = (unpack "n", substr $pkt, $ptr - 2, 2) & 0x3fff; |
372 |
} elsif ($len) { |
373 |
push @res, substr $pkt, $ptr, $len; |
374 |
$ptr += $len; |
375 |
} else { |
376 |
$ofs = $ptr if $ptr > $ofs; |
377 |
return join ".", @res; |
378 |
} |
379 |
} |
380 |
} |
381 |
|
382 |
sub _dec_qd { |
383 |
my $qname = _dec_name; |
384 |
my ($qt, $qc) = unpack "nn", substr $pkt, $ofs; $ofs += 4; |
385 |
[$qname, $type_str{$qt} || $qt, $class_str{$qc} || $qc] |
386 |
} |
387 |
|
388 |
our %dec_rr = ( |
389 |
1 => sub { join ".", unpack "C4", $_ }, # a |
390 |
2 => sub { local $ofs = $ofs - length; _dec_name }, # ns |
391 |
5 => sub { local $ofs = $ofs - length; _dec_name }, # cname |
392 |
6 => sub { |
393 |
local $ofs = $ofs - length; |
394 |
my $mname = _dec_name; |
395 |
my $rname = _dec_name; |
396 |
($mname, $rname, unpack "NNNNN", substr $pkt, $ofs) |
397 |
}, # soa |
398 |
11 => sub { ((join ".", unpack "C4", $_), unpack "C a*", substr $_, 4) }, # wks |
399 |
12 => sub { local $ofs = $ofs - length; _dec_name }, # ptr |
400 |
13 => sub { unpack "C/a* C/a*", $_ }, # hinfo |
401 |
15 => sub { local $ofs = $ofs + 2 - length; ((unpack "n", $_), _dec_name) }, # mx |
402 |
16 => sub { unpack "(C/a*)*", $_ }, # txt |
403 |
28 => sub { AnyEvent::Socket::format_address ($_) }, # aaaa |
404 |
33 => sub { local $ofs = $ofs + 6 - length; ((unpack "nnn", $_), _dec_name) }, # srv |
405 |
99 => sub { unpack "(C/a*)*", $_ }, # spf |
406 |
); |
407 |
|
408 |
sub _dec_rr { |
409 |
my $name = _dec_name; |
410 |
|
411 |
my ($rt, $rc, $ttl, $rdlen) = unpack "nn N n", substr $pkt, $ofs; $ofs += 10; |
412 |
local $_ = substr $pkt, $ofs, $rdlen; $ofs += $rdlen; |
413 |
|
414 |
[ |
415 |
$name, |
416 |
$type_str{$rt} || $rt, |
417 |
$class_str{$rc} || $rc, |
418 |
($dec_rr{$rt} || sub { $_ })->(), |
419 |
] |
420 |
} |
421 |
|
422 |
=item $dns = AnyEvent::DNS::dns_unpack $pkt |
423 |
|
424 |
Unpacks a DNS packet into a perl data structure. |
425 |
|
426 |
Examples: |
427 |
|
428 |
# an unsuccessful reply |
429 |
{ |
430 |
'qd' => [ |
431 |
[ 'ruth.plan9.de.mach.uni-karlsruhe.de', '*', 'in' ] |
432 |
], |
433 |
'rc' => 'nxdomain', |
434 |
'ar' => [], |
435 |
'ns' => [ |
436 |
[ |
437 |
'uni-karlsruhe.de', |
438 |
'soa', |
439 |
'in', |
440 |
'netserv.rz.uni-karlsruhe.de', |
441 |
'hostmaster.rz.uni-karlsruhe.de', |
442 |
2008052201, 10800, 1800, 2592000, 86400 |
443 |
] |
444 |
], |
445 |
'tc' => '', |
446 |
'ra' => 1, |
447 |
'qr' => 1, |
448 |
'id' => 45915, |
449 |
'aa' => '', |
450 |
'an' => [], |
451 |
'rd' => 1, |
452 |
'op' => 'query' |
453 |
} |
454 |
|
455 |
# a successful reply |
456 |
|
457 |
{ |
458 |
'qd' => [ [ 'www.google.de', 'a', 'in' ] ], |
459 |
'rc' => 0, |
460 |
'ar' => [ |
461 |
[ 'a.l.google.com', 'a', 'in', '209.85.139.9' ], |
462 |
[ 'b.l.google.com', 'a', 'in', '64.233.179.9' ], |
463 |
[ 'c.l.google.com', 'a', 'in', '64.233.161.9' ], |
464 |
], |
465 |
'ns' => [ |
466 |
[ 'l.google.com', 'ns', 'in', 'a.l.google.com' ], |
467 |
[ 'l.google.com', 'ns', 'in', 'b.l.google.com' ], |
468 |
], |
469 |
'tc' => '', |
470 |
'ra' => 1, |
471 |
'qr' => 1, |
472 |
'id' => 64265, |
473 |
'aa' => '', |
474 |
'an' => [ |
475 |
[ 'www.google.de', 'cname', 'in', 'www.google.com' ], |
476 |
[ 'www.google.com', 'cname', 'in', 'www.l.google.com' ], |
477 |
[ 'www.l.google.com', 'a', 'in', '66.249.93.104' ], |
478 |
[ 'www.l.google.com', 'a', 'in', '66.249.93.147' ], |
479 |
], |
480 |
'rd' => 1, |
481 |
'op' => 0 |
482 |
} |
483 |
|
484 |
=cut |
485 |
|
486 |
sub dns_unpack($) { |
487 |
local $pkt = shift; |
488 |
my ($id, $flags, $qd, $an, $ns, $ar) |
489 |
= unpack "nn nnnn A*", $pkt; |
490 |
|
491 |
local $ofs = 6 * 2; |
492 |
|
493 |
{ |
494 |
id => $id, |
495 |
qr => ! ! ($flags & 0x8000), |
496 |
aa => ! ! ($flags & 0x0400), |
497 |
tc => ! ! ($flags & 0x0200), |
498 |
rd => ! ! ($flags & 0x0100), |
499 |
ra => ! ! ($flags & 0x0080), |
500 |
ad => ! ! ($flags & 0x0020), |
501 |
cd => ! ! ($flags & 0x0010), |
502 |
op => $opcode_str{($flags & 0x001e) >> 11}, |
503 |
rc => $rcode_str{($flags & 0x000f)}, |
504 |
|
505 |
qd => [map _dec_qd, 1 .. $qd], |
506 |
an => [map _dec_rr, 1 .. $an], |
507 |
ns => [map _dec_rr, 1 .. $ns], |
508 |
ar => [map _dec_rr, 1 .. $ar], |
509 |
} |
510 |
} |
511 |
|
512 |
############################################################################# |
513 |
|
514 |
=back |
515 |
|
516 |
=head2 THE AnyEvent::DNS RESOLVER CLASS |
517 |
|
518 |
This is the class which does the actual protocol work. |
519 |
|
520 |
=over 4 |
521 |
|
522 |
=cut |
523 |
|
524 |
use Carp (); |
525 |
use Scalar::Util (); |
526 |
use Socket (); |
527 |
|
528 |
our $NOW; |
529 |
|
530 |
=item AnyEvent::DNS::resolver |
531 |
|
532 |
This function creates and returns a resolver that is ready to use and |
533 |
should mimic the default resolver for your system as good as possible. |
534 |
|
535 |
It only ever creates one resolver and returns this one on subsequent |
536 |
calls. |
537 |
|
538 |
Unless you have special needs, prefer this function over creating your own |
539 |
resolver object. |
540 |
|
541 |
=cut |
542 |
|
543 |
our $RESOLVER; |
544 |
|
545 |
sub resolver() { |
546 |
$RESOLVER || do { |
547 |
$RESOLVER = new AnyEvent::DNS; |
548 |
$RESOLVER->os_config; |
549 |
$RESOLVER |
550 |
} |
551 |
} |
552 |
|
553 |
=item $resolver = new AnyEvent::DNS key => value... |
554 |
|
555 |
Creates and returns a new resolver. |
556 |
|
557 |
The following options are supported: |
558 |
|
559 |
=over 4 |
560 |
|
561 |
=item server => [...] |
562 |
|
563 |
A list of server addresses (default: C<v127.0.0.1>) in network format (4 |
564 |
octets for IPv4, 16 octets for IPv6 - not yet supported). |
565 |
|
566 |
=item timeout => [...] |
567 |
|
568 |
A list of timeouts to use (also determines the number of retries). To make |
569 |
three retries with individual time-outs of 2, 5 and 5 seconds, use C<[2, |
570 |
5, 5]>, which is also the default. |
571 |
|
572 |
=item search => [...] |
573 |
|
574 |
The default search list of suffixes to append to a domain name (default: none). |
575 |
|
576 |
=item ndots => $integer |
577 |
|
578 |
The number of dots (default: C<1>) that a name must have so that the resolver |
579 |
tries to resolve the name without any suffixes first. |
580 |
|
581 |
=item max_outstanding => $integer |
582 |
|
583 |
Most name servers do not handle many parallel requests very well. This option |
584 |
limits the number of outstanding requests to C<$n> (default: C<10>), that means |
585 |
if you request more than this many requests, then the additional requests will be queued |
586 |
until some other requests have been resolved. |
587 |
|
588 |
=item reuse => $seconds |
589 |
|
590 |
The number of seconds (default: C<300>) that a query id cannot be re-used |
591 |
after a timeout. If there as no time-out then query id's can be reused |
592 |
immediately. |
593 |
|
594 |
=back |
595 |
|
596 |
=cut |
597 |
|
598 |
sub new { |
599 |
my ($class, %arg) = @_; |
600 |
|
601 |
# try to create a ipv4 and an ipv6 socket |
602 |
# only fail when we cnanot create either |
603 |
|
604 |
socket my $fh4, AF_INET , &Socket::SOCK_DGRAM, 0; |
605 |
socket my $fh6, AF_INET6, &Socket::SOCK_DGRAM, 0; |
606 |
|
607 |
$fh4 || $fh6 |
608 |
or Carp::croak "unable to create either an IPv6 or an IPv4 socket"; |
609 |
|
610 |
my $self = bless { |
611 |
server => [], |
612 |
timeout => [2, 5, 5], |
613 |
search => [], |
614 |
ndots => 1, |
615 |
max_outstanding => 10, |
616 |
reuse => 300, # reuse id's after 5 minutes only, if possible |
617 |
%arg, |
618 |
reuse_q => [], |
619 |
}, $class; |
620 |
|
621 |
# search should default to gethostname's domain |
622 |
# but perl lacks a good posix module |
623 |
|
624 |
Scalar::Util::weaken (my $wself = $self); |
625 |
|
626 |
if ($fh4) { |
627 |
AnyEvent::Util::fh_nonblocking $fh4, 1; |
628 |
$self->{fh4} = $fh4; |
629 |
$self->{rw4} = AnyEvent->io (fh => $fh4, poll => "r", cb => sub { |
630 |
if (my $peer = recv $fh4, my $pkt, MAX_PKT, 0) { |
631 |
$wself->_recv ($pkt, $peer); |
632 |
} |
633 |
}); |
634 |
} |
635 |
|
636 |
if ($fh6) { |
637 |
$self->{fh6} = $fh6; |
638 |
AnyEvent::Util::fh_nonblocking $fh6, 1; |
639 |
$self->{rw6} = AnyEvent->io (fh => $fh6, poll => "r", cb => sub { |
640 |
if (my $peer = recv $fh6, my $pkt, MAX_PKT, 0) { |
641 |
$wself->_recv ($pkt, $peer); |
642 |
} |
643 |
}); |
644 |
} |
645 |
|
646 |
$self->_compile; |
647 |
|
648 |
$self |
649 |
} |
650 |
|
651 |
=item $resolver->parse_resolv_conv ($string) |
652 |
|
653 |
Parses the given string as if it were a F<resolv.conf> file. The following |
654 |
directives are supported (but not necessarily implemented). |
655 |
|
656 |
C<#>-style comments, C<nameserver>, C<domain>, C<search>, C<sortlist>, |
657 |
C<options> (C<timeout>, C<attempts>, C<ndots>). |
658 |
|
659 |
Everything else is silently ignored. |
660 |
|
661 |
=cut |
662 |
|
663 |
sub parse_resolv_conf { |
664 |
my ($self, $resolvconf) = @_; |
665 |
|
666 |
$self->{server} = []; |
667 |
$self->{search} = []; |
668 |
|
669 |
my $attempts; |
670 |
|
671 |
for (split /\n/, $resolvconf) { |
672 |
if (/^\s*#/) { |
673 |
# comment |
674 |
} elsif (/^\s*nameserver\s+(\S+)\s*$/i) { |
675 |
my $ip = $1; |
676 |
if (my $ipn = AnyEvent::Socket::parse_address ($ip)) { |
677 |
push @{ $self->{server} }, $ipn; |
678 |
} else { |
679 |
warn "nameserver $ip invalid and ignored\n"; |
680 |
} |
681 |
} elsif (/^\s*domain\s+(\S*)\s+$/i) { |
682 |
$self->{search} = [$1]; |
683 |
} elsif (/^\s*search\s+(.*?)\s*$/i) { |
684 |
$self->{search} = [split /\s+/, $1]; |
685 |
} elsif (/^\s*sortlist\s+(.*?)\s*$/i) { |
686 |
# ignored, NYI |
687 |
} elsif (/^\s*options\s+(.*?)\s*$/i) { |
688 |
for (split /\s+/, $1) { |
689 |
if (/^timeout:(\d+)$/) { |
690 |
$self->{timeout} = [$1]; |
691 |
} elsif (/^attempts:(\d+)$/) { |
692 |
$attempts = $1; |
693 |
} elsif (/^ndots:(\d+)$/) { |
694 |
$self->{ndots} = $1; |
695 |
} else { |
696 |
# debug, rotate, no-check-names, inet6 |
697 |
} |
698 |
} |
699 |
} |
700 |
} |
701 |
|
702 |
$self->{timeout} = [($self->{timeout}[0]) x $attempts] |
703 |
if $attempts; |
704 |
|
705 |
$self->_compile; |
706 |
} |
707 |
|
708 |
=item $resolver->os_config |
709 |
|
710 |
Tries so load and parse F</etc/resolv.conf> on portable operating systems. Tries various |
711 |
egregious hacks on windows to force the DNS servers and searchlist out of the system. |
712 |
|
713 |
=cut |
714 |
|
715 |
sub os_config { |
716 |
my ($self) = @_; |
717 |
|
718 |
$self->{server} = []; |
719 |
$self->{search} = []; |
720 |
|
721 |
if (AnyEvent::WIN32 || $^O =~ /cygwin/i) { |
722 |
no strict 'refs'; |
723 |
|
724 |
# there are many options to find the current nameservers etc. on windows |
725 |
# all of them don't work consistently: |
726 |
# - the registry thing needs separate code on win32 native vs. cygwin |
727 |
# - the registry layout differs between windows versions |
728 |
# - calling windows api functions doesn't work on cygwin |
729 |
# - ipconfig uses locale-specific messages |
730 |
|
731 |
# we use ipconfig parsing because, despite all it's brokenness, |
732 |
# it seems most stable in practise. |
733 |
# for good measure, we append a fallback nameserver to our list. |
734 |
|
735 |
if (open my $fh, "ipconfig /all |") { |
736 |
# parsing strategy: we go through the output and look for |
737 |
# :-lines with DNS in them. everything in those is regarded as |
738 |
# either a nameserver (if it parses as an ip address), or a suffix |
739 |
# (all else). |
740 |
|
741 |
my $dns; |
742 |
while (<$fh>) { |
743 |
if (s/^\s.*\bdns\b.*://i) { |
744 |
$dns = 1; |
745 |
} elsif (/^\S/ || /^\s[^:]{16,}: /) { |
746 |
$dns = 0; |
747 |
} |
748 |
if ($dns && /^\s*(\S+)\s*$/) { |
749 |
my $s = $1; |
750 |
$s =~ s/%\d+(?!\S)//; # get rid of scope id |
751 |
if (my $ipn = AnyEvent::Socket::parse_address ($s)) { |
752 |
push @{ $self->{server} }, $ipn; |
753 |
} else { |
754 |
push @{ $self->{search} }, $s; |
755 |
} |
756 |
} |
757 |
} |
758 |
|
759 |
# always add one fallback server |
760 |
push @{ $self->{server} }, $DNS_FALLBACK[rand @DNS_FALLBACK]; |
761 |
|
762 |
$self->_compile; |
763 |
} |
764 |
} else { |
765 |
# try resolv.conf everywhere |
766 |
|
767 |
if (open my $fh, "</etc/resolv.conf") { |
768 |
local $/; |
769 |
$self->parse_resolv_conf (<$fh>); |
770 |
} |
771 |
} |
772 |
} |
773 |
|
774 |
sub _compile { |
775 |
my $self = shift; |
776 |
|
777 |
my %search; $self->{search} = [grep 0 < length, grep !$search{$_}++, @{ $self->{search} }]; |
778 |
my %server; $self->{server} = [grep 0 < length, grep !$server{$_}++, @{ $self->{server} }]; |
779 |
|
780 |
unless (@{ $self->{server} }) { |
781 |
# use 127.0.0.1 by default, and one opendns nameserver as fallback |
782 |
$self->{server} = [v127.0.0.1, $DNS_FALLBACK[rand @DNS_FALLBACK]]; |
783 |
} |
784 |
|
785 |
my @retry; |
786 |
|
787 |
for my $timeout (@{ $self->{timeout} }) { |
788 |
for my $server (@{ $self->{server} }) { |
789 |
push @retry, [$server, $timeout]; |
790 |
} |
791 |
} |
792 |
|
793 |
$self->{retry} = \@retry; |
794 |
} |
795 |
|
796 |
sub _feed { |
797 |
my ($self, $res) = @_; |
798 |
|
799 |
$res = dns_unpack $res |
800 |
or return; |
801 |
|
802 |
my $id = $self->{id}{$res->{id}}; |
803 |
|
804 |
return unless ref $id; |
805 |
|
806 |
$NOW = time; |
807 |
$id->[1]->($res); |
808 |
} |
809 |
|
810 |
sub _recv { |
811 |
my ($self, $pkt, $peer) = @_; |
812 |
|
813 |
# we ignore errors (often one gets port unreachable, but there is |
814 |
# no good way to take advantage of that. |
815 |
|
816 |
my ($port, $host) = AnyEvent::Socket::unpack_sockaddr ($peer); |
817 |
|
818 |
return unless $port == 53 && grep $_ eq $host, @{ $self->{server} }; |
819 |
|
820 |
$self->_feed ($pkt); |
821 |
} |
822 |
|
823 |
sub _free_id { |
824 |
my ($self, $id, $timeout) = @_; |
825 |
|
826 |
if ($timeout) { |
827 |
# we need to block the id for a while |
828 |
$self->{id}{$id} = 1; |
829 |
push @{ $self->{reuse_q} }, [$NOW + $self->{reuse}, $id]; |
830 |
} else { |
831 |
# we can quickly recycle the id |
832 |
delete $self->{id}{$id}; |
833 |
} |
834 |
|
835 |
--$self->{outstanding}; |
836 |
$self->_scheduler; |
837 |
} |
838 |
|
839 |
# execute a single request, involves sending it with timeouts to multiple servers |
840 |
sub _exec { |
841 |
my ($self, $req) = @_; |
842 |
|
843 |
my $retry; # of retries |
844 |
my $do_retry; |
845 |
|
846 |
$do_retry = sub { |
847 |
my $retry_cfg = $self->{retry}[$retry++] |
848 |
or do { |
849 |
# failure |
850 |
$self->_free_id ($req->[2], $retry > 1); |
851 |
undef $do_retry; return $req->[1]->(); |
852 |
}; |
853 |
|
854 |
my ($server, $timeout) = @$retry_cfg; |
855 |
|
856 |
$self->{id}{$req->[2]} = [AnyEvent->timer (after => $timeout, cb => sub { |
857 |
$NOW = time; |
858 |
|
859 |
# timeout, try next |
860 |
&$do_retry; |
861 |
}), sub { |
862 |
my ($res) = @_; |
863 |
|
864 |
if ($res->{tc}) { |
865 |
# success, but truncated, so use tcp |
866 |
AnyEvent::Socket::tcp_connect (AnyEvent::Socket::format_address ($server), DOMAIN_PORT, sub { |
867 |
my ($fh) = @_ |
868 |
or return &$do_retry; |
869 |
|
870 |
my $handle = new AnyEvent::Handle |
871 |
fh => $fh, |
872 |
on_error => sub { |
873 |
# failure, try next |
874 |
&$do_retry; |
875 |
}; |
876 |
|
877 |
$handle->push_write (pack "n/a", $req->[0]); |
878 |
$handle->push_read (chunk => 2, sub { |
879 |
$handle->unshift_read (chunk => (unpack "n", $_[1]), sub { |
880 |
$self->_feed ($_[1]); |
881 |
}); |
882 |
}); |
883 |
shutdown $fh, 1; |
884 |
|
885 |
}, sub { $timeout }); |
886 |
|
887 |
} else { |
888 |
# success |
889 |
$self->_free_id ($req->[2], $retry > 1); |
890 |
undef $do_retry; return $req->[1]->($res); |
891 |
} |
892 |
}]; |
893 |
|
894 |
my $sa = AnyEvent::Socket::pack_sockaddr (DOMAIN_PORT, $server); |
895 |
|
896 |
my $fh = (Socket::sockaddr_family $sa) == AF_INET |
897 |
? $self->{fh4} : $self->{fh6} |
898 |
or return &$do_retry; |
899 |
|
900 |
send $fh, $req->[0], 0, $sa; |
901 |
}; |
902 |
|
903 |
&$do_retry; |
904 |
} |
905 |
|
906 |
sub _scheduler { |
907 |
my ($self) = @_; |
908 |
|
909 |
$NOW = time; |
910 |
|
911 |
# first clear id reuse queue |
912 |
delete $self->{id}{ (shift @{ $self->{reuse_q} })->[1] } |
913 |
while @{ $self->{reuse_q} } && $self->{reuse_q}[0][0] <= $NOW; |
914 |
|
915 |
while ($self->{outstanding} < $self->{max_outstanding}) { |
916 |
|
917 |
if (@{ $self->{reuse_q} } >= 30000) { |
918 |
# we ran out of ID's, wait a bit |
919 |
$self->{reuse_to} ||= AnyEvent->timer (after => $self->{reuse_q}[0][0] - $NOW, cb => sub { |
920 |
delete $self->{reuse_to}; |
921 |
$self->_scheduler; |
922 |
}); |
923 |
last; |
924 |
} |
925 |
|
926 |
my $req = shift @{ $self->{queue} } |
927 |
or last; |
928 |
|
929 |
while () { |
930 |
$req->[2] = int rand 65536; |
931 |
last unless exists $self->{id}{$req->[2]}; |
932 |
} |
933 |
|
934 |
++$self->{outstanding}; |
935 |
$self->{id}{$req->[2]} = 1; |
936 |
substr $req->[0], 0, 2, pack "n", $req->[2]; |
937 |
|
938 |
$self->_exec ($req); |
939 |
} |
940 |
} |
941 |
|
942 |
=item $resolver->request ($req, $cb->($res)) |
943 |
|
944 |
Sends a single request (a hash-ref formated as specified for |
945 |
C<dns_pack>) to the configured nameservers including |
946 |
retries. Calls the callback with the decoded response packet if a reply |
947 |
was received, or no arguments on timeout. |
948 |
|
949 |
=cut |
950 |
|
951 |
sub request($$) { |
952 |
my ($self, $req, $cb) = @_; |
953 |
|
954 |
push @{ $self->{queue} }, [dns_pack $req, $cb]; |
955 |
$self->_scheduler; |
956 |
} |
957 |
|
958 |
=item $resolver->resolve ($qname, $qtype, %options, $cb->($rcode, @rr)) |
959 |
|
960 |
Queries the DNS for the given domain name C<$qname> of type C<$qtype> (a |
961 |
qtype of "*" is supported and means "any"). |
962 |
|
963 |
The callback will be invoked with a list of matching result records or |
964 |
none on any error or if the name could not be found. |
965 |
|
966 |
CNAME chains (although illegal) are followed up to a length of 8. |
967 |
|
968 |
Note that this resolver is just a stub resolver: it requires a name server |
969 |
supporting recursive queries, will not do any recursive queries itself and |
970 |
is not secure when used against an untrusted name server. |
971 |
|
972 |
The following options are supported: |
973 |
|
974 |
=over 4 |
975 |
|
976 |
=item search => [$suffix...] |
977 |
|
978 |
Use the given search list (which might be empty), by appending each one |
979 |
in turn to the C<$qname>. If this option is missing then the configured |
980 |
C<ndots> and C<search> define its value. If the C<$qname> ends in a dot, |
981 |
then the searchlist will be ignored. |
982 |
|
983 |
=item accept => [$type...] |
984 |
|
985 |
Lists the acceptable result types: only result types in this set will be |
986 |
accepted and returned. The default includes the C<$qtype> and nothing |
987 |
else. |
988 |
|
989 |
=item class => "class" |
990 |
|
991 |
Specify the query class ("in" for internet, "ch" for chaosnet and "hs" for |
992 |
hesiod are the only ones making sense). The default is "in", of course. |
993 |
|
994 |
=back |
995 |
|
996 |
Examples: |
997 |
|
998 |
$res->resolve ("ruth.plan9.de", "a", sub { |
999 |
warn Dumper [@_]; |
1000 |
}); |
1001 |
|
1002 |
[ |
1003 |
[ |
1004 |
'ruth.schmorp.de', |
1005 |
'a', |
1006 |
'in', |
1007 |
'129.13.162.95' |
1008 |
] |
1009 |
] |
1010 |
|
1011 |
$res->resolve ("test1.laendle", "*", |
1012 |
accept => ["a", "aaaa"], |
1013 |
sub { |
1014 |
warn Dumper [@_]; |
1015 |
} |
1016 |
); |
1017 |
|
1018 |
[ |
1019 |
[ |
1020 |
'test1.laendle', |
1021 |
'a', |
1022 |
'in', |
1023 |
'10.0.0.255' |
1024 |
], |
1025 |
[ |
1026 |
'test1.laendle', |
1027 |
'aaaa', |
1028 |
'in', |
1029 |
'3ffe:1900:4545:0002:0240:0000:0000:f7e1' |
1030 |
] |
1031 |
] |
1032 |
|
1033 |
=cut |
1034 |
|
1035 |
sub resolve($%) { |
1036 |
my $cb = pop; |
1037 |
my ($self, $qname, $qtype, %opt) = @_; |
1038 |
|
1039 |
my @search = $qname =~ s/\.$// |
1040 |
? "" |
1041 |
: $opt{search} |
1042 |
? @{ $opt{search} } |
1043 |
: ($qname =~ y/.//) >= $self->{ndots} |
1044 |
? ("", @{ $self->{search} }) |
1045 |
: (@{ $self->{search} }, ""); |
1046 |
|
1047 |
my $class = $opt{class} || "in"; |
1048 |
|
1049 |
my %atype = $opt{accept} |
1050 |
? map +($_ => 1), @{ $opt{accept} } |
1051 |
: ($qtype => 1); |
1052 |
|
1053 |
# advance in searchlist |
1054 |
my ($do_search, $do_req); |
1055 |
|
1056 |
$do_search = sub { |
1057 |
@search |
1058 |
or (undef $do_search), (undef $do_req), return $cb->(); |
1059 |
|
1060 |
(my $name = lc "$qname." . shift @search) =~ s/\.$//; |
1061 |
my $depth = 2; |
1062 |
|
1063 |
# advance in cname-chain |
1064 |
$do_req = sub { |
1065 |
$self->request ({ |
1066 |
rd => 1, |
1067 |
qd => [[$name, $qtype, $class]], |
1068 |
}, sub { |
1069 |
my ($res) = @_ |
1070 |
or return $do_search->(); |
1071 |
|
1072 |
my $cname; |
1073 |
|
1074 |
while () { |
1075 |
# results found? |
1076 |
my @rr = grep $name eq lc $_->[0] && ($atype{"*"} || $atype{$_->[1]}), @{ $res->{an} }; |
1077 |
|
1078 |
(undef $do_search), (undef $do_req), return $cb->(@rr) |
1079 |
if @rr; |
1080 |
|
1081 |
# see if there is a cname we can follow |
1082 |
my @rr = grep $name eq lc $_->[0] && $_->[1] eq "cname", @{ $res->{an} }; |
1083 |
|
1084 |
if (@rr) { |
1085 |
$depth-- |
1086 |
or return $do_search->(); # cname chain too long |
1087 |
|
1088 |
$cname = 1; |
1089 |
$name = $rr[0][3]; |
1090 |
|
1091 |
} elsif ($cname) { |
1092 |
# follow the cname |
1093 |
return $do_req->(); |
1094 |
|
1095 |
} else { |
1096 |
# no, not found anything |
1097 |
return $do_search->(); |
1098 |
} |
1099 |
} |
1100 |
}); |
1101 |
}; |
1102 |
|
1103 |
$do_req->(); |
1104 |
}; |
1105 |
|
1106 |
$do_search->(); |
1107 |
} |
1108 |
|
1109 |
use AnyEvent::Socket (); # circular dependency, so do not import anything and do it at the end |
1110 |
|
1111 |
1; |
1112 |
|
1113 |
=back |
1114 |
|
1115 |
=head1 AUTHOR |
1116 |
|
1117 |
Marc Lehmann <schmorp@schmorp.de> |
1118 |
http://home.schmorp.de/ |
1119 |
|
1120 |
=cut |
1121 |
|