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 qw(WIN32); |
37 |
use AnyEvent::Handle (); |
38 |
|
39 |
our @DNS_FALLBACK = (v208.67.220.220, v208.67.222.222); |
40 |
|
41 |
=item AnyEvent::DNS::addr $node, $service, $proto, $family, $type, $cb->([$family, $type, $proto, $sockaddr], ...) |
42 |
|
43 |
Tries to resolve the given nodename and service name into protocol families |
44 |
and sockaddr structures usable to connect to this node and service in a |
45 |
protocol-independent way. It works remotely similar to the getaddrinfo |
46 |
posix function. |
47 |
|
48 |
C<$node> is either an IPv4 or IPv6 address or a hostname, C<$service> is |
49 |
either a service name (port name from F</etc/services>) or a numerical |
50 |
port number. If both C<$node> and C<$service> are names, then SRV records |
51 |
will be consulted to find the real service, otherwise they will be |
52 |
used as-is. If you know that the service name is not in your services |
53 |
database, then you can specify the service in the format C<name=port> |
54 |
(e.g. C<http=80>). |
55 |
|
56 |
C<$proto> must be a protocol name, currently C<tcp>, C<udp> or |
57 |
C<sctp>. The default is C<tcp>. |
58 |
|
59 |
C<$family> must be either C<0> (meaning any protocol is OK), C<4> (use |
60 |
only IPv4) or C<6> (use only IPv6). This setting might be influenced by |
61 |
C<$ENV{PERL_ANYEVENT_PROTOCOLS}>. |
62 |
|
63 |
C<$type> must be C<SOCK_STREAM>, C<SOCK_DGRAM> or C<SOCK_SEQPACKET> (or |
64 |
C<undef> in which case it gets automatically chosen). |
65 |
|
66 |
The callback will receive zero or more array references that contain |
67 |
C<$family, $type, $proto> for use in C<socket> and a binary |
68 |
C<$sockaddr> for use in C<connect> (or C<bind>). |
69 |
|
70 |
The application should try these in the order given. |
71 |
|
72 |
Example: |
73 |
|
74 |
AnyEvent::DNS::addr "google.com", "http", 0, undef, undef, sub { ... }; |
75 |
|
76 |
=item AnyEvent::DNS::a $domain, $cb->(@addrs) |
77 |
|
78 |
Tries to resolve the given domain to IPv4 address(es). |
79 |
|
80 |
=item AnyEvent::DNS::aaaa $domain, $cb->(@addrs) |
81 |
|
82 |
Tries to resolve the given domain to IPv6 address(es). |
83 |
|
84 |
=item AnyEvent::DNS::mx $domain, $cb->(@hostnames) |
85 |
|
86 |
Tries to resolve the given domain into a sorted (lower preference value |
87 |
first) list of domain names. |
88 |
|
89 |
=item AnyEvent::DNS::ns $domain, $cb->(@hostnames) |
90 |
|
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Tries to resolve the given domain name into a list of name servers. |
92 |
|
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=item AnyEvent::DNS::txt $domain, $cb->(@hostnames) |
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|
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Tries to resolve the given domain name into a list of text records. |
96 |
|
97 |
=item AnyEvent::DNS::srv $service, $proto, $domain, $cb->(@srv_rr) |
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|
99 |
Tries to resolve the given service, protocol and domain name into a list |
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of service records. |
101 |
|
102 |
Each srv_rr is an array reference with the following contents: |
103 |
C<[$priority, $weight, $transport, $target]>. |
104 |
|
105 |
They will be sorted with lowest priority, highest weight first (TODO: |
106 |
should use the RFC algorithm to reorder same-priority records for weight). |
107 |
|
108 |
Example: |
109 |
|
110 |
AnyEvent::DNS::srv "sip", "udp", "schmorp.de", sub { ... |
111 |
# @_ = ( [10, 10, 5060, "sip1.schmorp.de" ] ) |
112 |
|
113 |
=item AnyEvent::DNS::ptr $ipv4_or_6, $cb->(@hostnames) |
114 |
|
115 |
Tries to reverse-resolve the given IPv4 or IPv6 address (in textual form) |
116 |
into it's hostname(s). |
117 |
|
118 |
Example: |
119 |
|
120 |
AnyEvent::DNS::ptr "2001:500:2f::f", sub { print shift }; |
121 |
# => f.root-servers.net |
122 |
|
123 |
=item AnyEvent::DNS::any $domain, $cb->(@rrs) |
124 |
|
125 |
Tries to resolve the given domain and passes all resource records found to |
126 |
the callback. |
127 |
|
128 |
=cut |
129 |
|
130 |
sub resolver; |
131 |
|
132 |
sub a($$) { |
133 |
my ($domain, $cb) = @_; |
134 |
|
135 |
resolver->resolve ($domain => "a", sub { |
136 |
$cb->(map $_->[3], @_); |
137 |
}); |
138 |
} |
139 |
|
140 |
sub aaaa($$) { |
141 |
my ($domain, $cb) = @_; |
142 |
|
143 |
resolver->resolve ($domain => "aaaa", sub { |
144 |
$cb->(map $_->[3], @_); |
145 |
}); |
146 |
} |
147 |
|
148 |
sub mx($$) { |
149 |
my ($domain, $cb) = @_; |
150 |
|
151 |
resolver->resolve ($domain => "mx", sub { |
152 |
$cb->(map $_->[4], sort { $a->[3] <=> $b->[3] } @_); |
153 |
}); |
154 |
} |
155 |
|
156 |
sub ns($$) { |
157 |
my ($domain, $cb) = @_; |
158 |
|
159 |
resolver->resolve ($domain => "ns", sub { |
160 |
$cb->(map $_->[3], @_); |
161 |
}); |
162 |
} |
163 |
|
164 |
sub txt($$) { |
165 |
my ($domain, $cb) = @_; |
166 |
|
167 |
resolver->resolve ($domain => "txt", sub { |
168 |
$cb->(map $_->[3], @_); |
169 |
}); |
170 |
} |
171 |
|
172 |
sub srv($$$$) { |
173 |
my ($service, $proto, $domain, $cb) = @_; |
174 |
|
175 |
# todo, ask for any and check glue records |
176 |
resolver->resolve ("_$service._$proto.$domain" => "srv", sub { |
177 |
$cb->(map [@$_[3,4,5,6]], sort { $a->[3] <=> $b->[3] || $b->[4] <=> $a->[4] } @_); |
178 |
}); |
179 |
} |
180 |
|
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sub ptr($$) { |
182 |
my ($ip, $cb) = @_; |
183 |
|
184 |
$ip = AnyEvent::Socket::parse_ip ($ip) |
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or return $cb->(); |
186 |
|
187 |
if (4 == length $ip) { |
188 |
$ip = join ".", (reverse split /\./, $ip), "in-addr.arpa."; |
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} else { |
190 |
$ip = join ".", (reverse split //, unpack "H*", $ip), "ip6.arpa."; |
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} |
192 |
|
193 |
resolver->resolve ($ip => "ptr", sub { |
194 |
$cb->(map $_->[3], @_); |
195 |
}); |
196 |
} |
197 |
|
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sub any($$) { |
199 |
my ($domain, $cb) = @_; |
200 |
|
201 |
resolver->resolve ($domain => "*", $cb); |
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} |
203 |
|
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############################################################################# |
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|
206 |
sub addr($$$$$$) { |
207 |
my ($node, $service, $proto, $family, $type, $cb) = @_; |
208 |
|
209 |
unless (&AnyEvent::Util::AF_INET6) { |
210 |
$family != 6 |
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or return $cb->(); |
212 |
|
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$family ||= 4; |
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} |
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|
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$cb->() if $family == 4 && !$AnyEvent::PROTOCOL{ipv4}; |
217 |
$cb->() if $family == 6 && !$AnyEvent::PROTOCOL{ipv6}; |
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|
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$family ||=4 unless $AnyEvent::PROTOCOL{ipv6}; |
220 |
$family ||=6 unless $AnyEvent::PROTOCOL{ipv4}; |
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|
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$proto ||= "tcp"; |
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$type ||= $proto eq "udp" ? SOCK_DGRAM : SOCK_STREAM; |
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|
225 |
my $proton = (getprotobyname $proto)[2] |
226 |
or Carp::croak "$proto: protocol unknown"; |
227 |
|
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my $port; |
229 |
|
230 |
if ($service =~ /^(\S+)=(\d+)$/) { |
231 |
($service, $port) = ($1, $2); |
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} elsif ($service =~ /^\d+$/) { |
233 |
($service, $port) = (undef, $service); |
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} else { |
235 |
$port = (getservbyname $service, $proto)[2] |
236 |
or Carp::croak "$service/$proto: service unknown"; |
237 |
} |
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|
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my @target = [$node, $port]; |
240 |
|
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# resolve a records / provide sockaddr structures |
242 |
my $resolve = sub { |
243 |
my @res; |
244 |
my $cv = AnyEvent->condvar (cb => sub { |
245 |
$cb->( |
246 |
map $_->[2], |
247 |
sort { |
248 |
$AnyEvent::PROTOCOL{$b->[1]} <=> $AnyEvent::PROTOCOL{$a->[1]} |
249 |
or $a->[0] <=> $b->[0] |
250 |
} |
251 |
@res |
252 |
) |
253 |
}); |
254 |
|
255 |
$cv->begin; |
256 |
for my $idx (0 .. $#target) { |
257 |
my ($node, $port) = @{ $target[$idx] }; |
258 |
|
259 |
if (my $noden = AnyEvent::Socket::parse_ip ($node)) { |
260 |
if (4 == length $noden && $family != 6) { |
261 |
push @res, [$idx, "ipv4", [AF_INET, $type, $proton, |
262 |
AnyEvent::Socket::pack_sockaddr ($port, $noden)]] |
263 |
} |
264 |
|
265 |
if (16 == length $noden && $family != 4) { |
266 |
push @res, [$idx, "ipv6", [&AnyEvent::Util::AF_INET6, $type, $proton, |
267 |
AnyEvent::Socket::pack_sockaddr ( $port, $noden)]] |
268 |
} |
269 |
} else { |
270 |
# ipv4 |
271 |
if ($family != 6) { |
272 |
$cv->begin; |
273 |
a $node, sub { |
274 |
push @res, [$idx, "ipv4", [AF_INET, $type, $proton, |
275 |
AnyEvent::Socket::pack_sockaddr ($port, AnyEvent::Socket::parse_ipv4 ($_))]] |
276 |
for @_; |
277 |
$cv->end; |
278 |
}; |
279 |
} |
280 |
|
281 |
# ipv6 |
282 |
if ($family != 4) { |
283 |
$cv->begin; |
284 |
aaaa $node, sub { |
285 |
push @res, [$idx, "ipv6", [&AnyEvent::Socket::AF_INET6, $type, $proton, |
286 |
AnyEvent::Socket::pack_sockaddr ($port, AnyEvent::Socket::parse_ipv6 ($_))]] |
287 |
for @_; |
288 |
$cv->end; |
289 |
}; |
290 |
} |
291 |
} |
292 |
} |
293 |
$cv->end; |
294 |
}; |
295 |
|
296 |
# try srv records, if applicable |
297 |
if ($node eq "localhost") { |
298 |
@target = (["127.0.0.1", $port], ["::1", $port]); |
299 |
&$resolve; |
300 |
} elsif (defined $service && !AnyEvent::Socket::parse_ip ($node)) { |
301 |
srv $service, $proto, $node, sub { |
302 |
my (@srv) = @_; |
303 |
|
304 |
# no srv records, continue traditionally |
305 |
@srv |
306 |
or return &$resolve; |
307 |
|
308 |
# only srv record has "." => abort |
309 |
$srv[0][2] ne "." || $#srv |
310 |
or return $cb->(); |
311 |
|
312 |
# use srv records then |
313 |
@target = map ["$_->[3].", $_->[2]], |
314 |
grep $_->[3] ne ".", |
315 |
@srv; |
316 |
|
317 |
&$resolve; |
318 |
}; |
319 |
} else { |
320 |
&$resolve; |
321 |
} |
322 |
} |
323 |
|
324 |
############################################################################# |
325 |
|
326 |
=back |
327 |
|
328 |
=head2 LOW-LEVEL DNS EN-/DECODING FUNCTIONS |
329 |
|
330 |
=over 4 |
331 |
|
332 |
=item $AnyEvent::DNS::EDNS0 |
333 |
|
334 |
This variable decides whether dns_pack automatically enables EDNS0 |
335 |
support. By default, this is disabled (C<0>), unless overridden by |
336 |
C<$ENV{PERL_ANYEVENT_EDNS0>), but when set to C<1>, AnyEvent::DNS will use |
337 |
EDNS0 in all requests. |
338 |
|
339 |
=cut |
340 |
|
341 |
our $EDNS0 = $ENV{PERL_ANYEVENT_EDNS0} * 1; # set to 1 to enable (partial) edns0 |
342 |
|
343 |
our %opcode_id = ( |
344 |
query => 0, |
345 |
iquery => 1, |
346 |
status => 2, |
347 |
notify => 4, |
348 |
update => 5, |
349 |
map +($_ => $_), 3, 6..15 |
350 |
); |
351 |
|
352 |
our %opcode_str = reverse %opcode_id; |
353 |
|
354 |
our %rcode_id = ( |
355 |
noerror => 0, |
356 |
formerr => 1, |
357 |
servfail => 2, |
358 |
nxdomain => 3, |
359 |
notimp => 4, |
360 |
refused => 5, |
361 |
yxdomain => 6, # Name Exists when it should not [RFC 2136] |
362 |
yxrrset => 7, # RR Set Exists when it should not [RFC 2136] |
363 |
nxrrset => 8, # RR Set that should exist does not [RFC 2136] |
364 |
notauth => 9, # Server Not Authoritative for zone [RFC 2136] |
365 |
notzone => 10, # Name not contained in zone [RFC 2136] |
366 |
# EDNS0 16 BADVERS Bad OPT Version [RFC 2671] |
367 |
# EDNS0 16 BADSIG TSIG Signature Failure [RFC 2845] |
368 |
# EDNS0 17 BADKEY Key not recognized [RFC 2845] |
369 |
# EDNS0 18 BADTIME Signature out of time window [RFC 2845] |
370 |
# EDNS0 19 BADMODE Bad TKEY Mode [RFC 2930] |
371 |
# EDNS0 20 BADNAME Duplicate key name [RFC 2930] |
372 |
# EDNS0 21 BADALG Algorithm not supported [RFC 2930] |
373 |
map +($_ => $_), 11..15 |
374 |
); |
375 |
|
376 |
our %rcode_str = reverse %rcode_id; |
377 |
|
378 |
our %type_id = ( |
379 |
a => 1, |
380 |
ns => 2, |
381 |
md => 3, |
382 |
mf => 4, |
383 |
cname => 5, |
384 |
soa => 6, |
385 |
mb => 7, |
386 |
mg => 8, |
387 |
mr => 9, |
388 |
null => 10, |
389 |
wks => 11, |
390 |
ptr => 12, |
391 |
hinfo => 13, |
392 |
minfo => 14, |
393 |
mx => 15, |
394 |
txt => 16, |
395 |
aaaa => 28, |
396 |
srv => 33, |
397 |
opt => 41, |
398 |
spf => 99, |
399 |
tkey => 249, |
400 |
tsig => 250, |
401 |
ixfr => 251, |
402 |
axfr => 252, |
403 |
mailb => 253, |
404 |
"*" => 255, |
405 |
); |
406 |
|
407 |
our %type_str = reverse %type_id; |
408 |
|
409 |
our %class_id = ( |
410 |
in => 1, |
411 |
ch => 3, |
412 |
hs => 4, |
413 |
none => 254, |
414 |
"*" => 255, |
415 |
); |
416 |
|
417 |
our %class_str = reverse %class_id; |
418 |
|
419 |
# names MUST have a trailing dot |
420 |
sub _enc_qname($) { |
421 |
pack "(C/a*)*", (split /\./, shift), "" |
422 |
} |
423 |
|
424 |
sub _enc_qd() { |
425 |
(_enc_qname $_->[0]) . pack "nn", |
426 |
($_->[1] > 0 ? $_->[1] : $type_id {$_->[1]}), |
427 |
($_->[2] > 0 ? $_->[2] : $class_id{$_->[2] || "in"}) |
428 |
} |
429 |
|
430 |
sub _enc_rr() { |
431 |
die "encoding of resource records is not supported"; |
432 |
} |
433 |
|
434 |
=item $pkt = AnyEvent::DNS::dns_pack $dns |
435 |
|
436 |
Packs a perl data structure into a DNS packet. Reading RFC1034 is strongly |
437 |
recommended, then everything will be totally clear. Or maybe not. |
438 |
|
439 |
Resource records are not yet encodable. |
440 |
|
441 |
Examples: |
442 |
|
443 |
# very simple request, using lots of default values: |
444 |
{ rd => 1, qd => [ [ "host.domain", "a"] ] } |
445 |
|
446 |
# more complex example, showing how flags etc. are named: |
447 |
|
448 |
{ |
449 |
id => 10000, |
450 |
op => "query", |
451 |
rc => "nxdomain", |
452 |
|
453 |
# flags |
454 |
qr => 1, |
455 |
aa => 0, |
456 |
tc => 0, |
457 |
rd => 0, |
458 |
ra => 0, |
459 |
ad => 0, |
460 |
cd => 0, |
461 |
|
462 |
qd => [@rr], # query section |
463 |
an => [@rr], # answer section |
464 |
ns => [@rr], # authority section |
465 |
ar => [@rr], # additional records section |
466 |
} |
467 |
|
468 |
=cut |
469 |
|
470 |
sub dns_pack($) { |
471 |
my ($req) = @_; |
472 |
|
473 |
pack "nn nnnn a* a* a* a* a*", |
474 |
$req->{id}, |
475 |
|
476 |
! !$req->{qr} * 0x8000 |
477 |
+ $opcode_id{$req->{op}} * 0x0800 |
478 |
+ ! !$req->{aa} * 0x0400 |
479 |
+ ! !$req->{tc} * 0x0200 |
480 |
+ ! !$req->{rd} * 0x0100 |
481 |
+ ! !$req->{ra} * 0x0080 |
482 |
+ ! !$req->{ad} * 0x0020 |
483 |
+ ! !$req->{cd} * 0x0010 |
484 |
+ $rcode_id{$req->{rc}} * 0x0001, |
485 |
|
486 |
scalar @{ $req->{qd} || [] }, |
487 |
scalar @{ $req->{an} || [] }, |
488 |
scalar @{ $req->{ns} || [] }, |
489 |
$EDNS0 + scalar @{ $req->{ar} || [] }, # include EDNS0 option here |
490 |
|
491 |
(join "", map _enc_qd, @{ $req->{qd} || [] }), |
492 |
(join "", map _enc_rr, @{ $req->{an} || [] }), |
493 |
(join "", map _enc_rr, @{ $req->{ns} || [] }), |
494 |
(join "", map _enc_rr, @{ $req->{ar} || [] }), |
495 |
|
496 |
($EDNS0 ? pack "C nnNn", 0, 41, 4096, 0, 0 : "") # EDNS0, 4kiB udp payload size |
497 |
} |
498 |
|
499 |
our $ofs; |
500 |
our $pkt; |
501 |
|
502 |
# bitches |
503 |
sub _dec_qname { |
504 |
my @res; |
505 |
my $redir; |
506 |
my $ptr = $ofs; |
507 |
my $cnt; |
508 |
|
509 |
while () { |
510 |
return undef if ++$cnt >= 256; # to avoid DoS attacks |
511 |
|
512 |
my $len = ord substr $pkt, $ptr++, 1; |
513 |
|
514 |
if ($len & 0xc0) { |
515 |
$ptr++; |
516 |
$ofs = $ptr if $ptr > $ofs; |
517 |
$ptr = (unpack "n", substr $pkt, $ptr - 2, 2) & 0x3fff; |
518 |
} elsif ($len) { |
519 |
push @res, substr $pkt, $ptr, $len; |
520 |
$ptr += $len; |
521 |
} else { |
522 |
$ofs = $ptr if $ptr > $ofs; |
523 |
return join ".", @res; |
524 |
} |
525 |
} |
526 |
} |
527 |
|
528 |
sub _dec_qd { |
529 |
my $qname = _dec_qname; |
530 |
my ($qt, $qc) = unpack "nn", substr $pkt, $ofs; $ofs += 4; |
531 |
[$qname, $type_str{$qt} || $qt, $class_str{$qc} || $qc] |
532 |
} |
533 |
|
534 |
our %dec_rr = ( |
535 |
1 => sub { join ".", unpack "C4", $_ }, # a |
536 |
2 => sub { local $ofs = $ofs - length; _dec_qname }, # ns |
537 |
5 => sub { local $ofs = $ofs - length; _dec_qname }, # cname |
538 |
6 => sub { |
539 |
local $ofs = $ofs - length; |
540 |
my $mname = _dec_qname; |
541 |
my $rname = _dec_qname; |
542 |
($mname, $rname, unpack "NNNNN", substr $pkt, $ofs) |
543 |
}, # soa |
544 |
11 => sub { ((join ".", unpack "C4", $_), unpack "C a*", substr $_, 4) }, # wks |
545 |
12 => sub { local $ofs = $ofs - length; _dec_qname }, # ptr |
546 |
13 => sub { unpack "C/a* C/a*", $_ }, # hinfo |
547 |
15 => sub { local $ofs = $ofs + 2 - length; ((unpack "n", $_), _dec_qname) }, # mx |
548 |
16 => sub { unpack "(C/a*)*", $_ }, # txt |
549 |
28 => sub { AnyEvent::Socket::format_ip ($_) }, # aaaa |
550 |
33 => sub { local $ofs = $ofs + 6 - length; ((unpack "nnn", $_), _dec_qname) }, # srv |
551 |
99 => sub { unpack "(C/a*)*", $_ }, # spf |
552 |
); |
553 |
|
554 |
sub _dec_rr { |
555 |
my $qname = _dec_qname; |
556 |
|
557 |
my ($rt, $rc, $ttl, $rdlen) = unpack "nn N n", substr $pkt, $ofs; $ofs += 10; |
558 |
local $_ = substr $pkt, $ofs, $rdlen; $ofs += $rdlen; |
559 |
|
560 |
[ |
561 |
$qname, |
562 |
$type_str{$rt} || $rt, |
563 |
$class_str{$rc} || $rc, |
564 |
($dec_rr{$rt} || sub { $_ })->(), |
565 |
] |
566 |
} |
567 |
|
568 |
=item $dns = AnyEvent::DNS::dns_unpack $pkt |
569 |
|
570 |
Unpacks a DNS packet into a perl data structure. |
571 |
|
572 |
Examples: |
573 |
|
574 |
# an unsuccessful reply |
575 |
{ |
576 |
'qd' => [ |
577 |
[ 'ruth.plan9.de.mach.uni-karlsruhe.de', '*', 'in' ] |
578 |
], |
579 |
'rc' => 'nxdomain', |
580 |
'ar' => [], |
581 |
'ns' => [ |
582 |
[ |
583 |
'uni-karlsruhe.de', |
584 |
'soa', |
585 |
'in', |
586 |
'netserv.rz.uni-karlsruhe.de', |
587 |
'hostmaster.rz.uni-karlsruhe.de', |
588 |
2008052201, 10800, 1800, 2592000, 86400 |
589 |
] |
590 |
], |
591 |
'tc' => '', |
592 |
'ra' => 1, |
593 |
'qr' => 1, |
594 |
'id' => 45915, |
595 |
'aa' => '', |
596 |
'an' => [], |
597 |
'rd' => 1, |
598 |
'op' => 'query' |
599 |
} |
600 |
|
601 |
# a successful reply |
602 |
|
603 |
{ |
604 |
'qd' => [ [ 'www.google.de', 'a', 'in' ] ], |
605 |
'rc' => 0, |
606 |
'ar' => [ |
607 |
[ 'a.l.google.com', 'a', 'in', '209.85.139.9' ], |
608 |
[ 'b.l.google.com', 'a', 'in', '64.233.179.9' ], |
609 |
[ 'c.l.google.com', 'a', 'in', '64.233.161.9' ], |
610 |
], |
611 |
'ns' => [ |
612 |
[ 'l.google.com', 'ns', 'in', 'a.l.google.com' ], |
613 |
[ 'l.google.com', 'ns', 'in', 'b.l.google.com' ], |
614 |
], |
615 |
'tc' => '', |
616 |
'ra' => 1, |
617 |
'qr' => 1, |
618 |
'id' => 64265, |
619 |
'aa' => '', |
620 |
'an' => [ |
621 |
[ 'www.google.de', 'cname', 'in', 'www.google.com' ], |
622 |
[ 'www.google.com', 'cname', 'in', 'www.l.google.com' ], |
623 |
[ 'www.l.google.com', 'a', 'in', '66.249.93.104' ], |
624 |
[ 'www.l.google.com', 'a', 'in', '66.249.93.147' ], |
625 |
], |
626 |
'rd' => 1, |
627 |
'op' => 0 |
628 |
} |
629 |
|
630 |
=cut |
631 |
|
632 |
sub dns_unpack($) { |
633 |
local $pkt = shift; |
634 |
my ($id, $flags, $qd, $an, $ns, $ar) |
635 |
= unpack "nn nnnn A*", $pkt; |
636 |
|
637 |
local $ofs = 6 * 2; |
638 |
|
639 |
{ |
640 |
id => $id, |
641 |
qr => ! ! ($flags & 0x8000), |
642 |
aa => ! ! ($flags & 0x0400), |
643 |
tc => ! ! ($flags & 0x0200), |
644 |
rd => ! ! ($flags & 0x0100), |
645 |
ra => ! ! ($flags & 0x0080), |
646 |
ad => ! ! ($flags & 0x0020), |
647 |
cd => ! ! ($flags & 0x0010), |
648 |
op => $opcode_str{($flags & 0x001e) >> 11}, |
649 |
rc => $rcode_str{($flags & 0x000f)}, |
650 |
|
651 |
qd => [map _dec_qd, 1 .. $qd], |
652 |
an => [map _dec_rr, 1 .. $an], |
653 |
ns => [map _dec_rr, 1 .. $ns], |
654 |
ar => [map _dec_rr, 1 .. $ar], |
655 |
} |
656 |
} |
657 |
|
658 |
############################################################################# |
659 |
|
660 |
=back |
661 |
|
662 |
=head2 THE AnyEvent::DNS RESOLVER CLASS |
663 |
|
664 |
This is the class which does the actual protocol work. |
665 |
|
666 |
=over 4 |
667 |
|
668 |
=cut |
669 |
|
670 |
use Carp (); |
671 |
use Scalar::Util (); |
672 |
use Socket (); |
673 |
|
674 |
our $NOW; |
675 |
|
676 |
=item AnyEvent::DNS::resolver |
677 |
|
678 |
This function creates and returns a resolver that is ready to use and |
679 |
should mimic the default resolver for your system as good as possible. |
680 |
|
681 |
It only ever creates one resolver and returns this one on subsequent |
682 |
calls. |
683 |
|
684 |
Unless you have special needs, prefer this function over creating your own |
685 |
resolver object. |
686 |
|
687 |
=cut |
688 |
|
689 |
our $RESOLVER; |
690 |
|
691 |
sub resolver() { |
692 |
$RESOLVER || do { |
693 |
$RESOLVER = new AnyEvent::DNS; |
694 |
$RESOLVER->os_config; |
695 |
$RESOLVER |
696 |
} |
697 |
} |
698 |
|
699 |
=item $resolver = new AnyEvent::DNS key => value... |
700 |
|
701 |
Creates and returns a new resolver. |
702 |
|
703 |
The following options are supported: |
704 |
|
705 |
=over 4 |
706 |
|
707 |
=item server => [...] |
708 |
|
709 |
A list of server addresses (default: C<v127.0.0.1>) in network format (4 |
710 |
octets for IPv4, 16 octets for IPv6 - not yet supported). |
711 |
|
712 |
=item timeout => [...] |
713 |
|
714 |
A list of timeouts to use (also determines the number of retries). To make |
715 |
three retries with individual time-outs of 2, 5 and 5 seconds, use C<[2, |
716 |
5, 5]>, which is also the default. |
717 |
|
718 |
=item search => [...] |
719 |
|
720 |
The default search list of suffixes to append to a domain name (default: none). |
721 |
|
722 |
=item ndots => $integer |
723 |
|
724 |
The number of dots (default: C<1>) that a name must have so that the resolver |
725 |
tries to resolve the name without any suffixes first. |
726 |
|
727 |
=item max_outstanding => $integer |
728 |
|
729 |
Most name servers do not handle many parallel requests very well. This option |
730 |
limits the number of outstanding requests to C<$n> (default: C<10>), that means |
731 |
if you request more than this many requests, then the additional requests will be queued |
732 |
until some other requests have been resolved. |
733 |
|
734 |
=item reuse => $seconds |
735 |
|
736 |
The number of seconds (default: C<300>) that a query id cannot be re-used |
737 |
after a timeout. If there as no time-out then query id's can be reused |
738 |
immediately. |
739 |
|
740 |
=back |
741 |
|
742 |
=cut |
743 |
|
744 |
sub new { |
745 |
my ($class, %arg) = @_; |
746 |
|
747 |
socket my $fh, AF_INET, &Socket::SOCK_DGRAM, 0 |
748 |
or Carp::croak "socket: $!"; |
749 |
|
750 |
AnyEvent::Util::fh_nonblocking $fh, 1; |
751 |
|
752 |
my $self = bless { |
753 |
server => [], |
754 |
timeout => [2, 5, 5], |
755 |
search => [], |
756 |
ndots => 1, |
757 |
max_outstanding => 10, |
758 |
reuse => 300, # reuse id's after 5 minutes only, if possible |
759 |
%arg, |
760 |
fh => $fh, |
761 |
reuse_q => [], |
762 |
}, $class; |
763 |
|
764 |
# search should default to gethostname's domain |
765 |
# but perl lacks a good posix module |
766 |
|
767 |
Scalar::Util::weaken (my $wself = $self); |
768 |
$self->{rw} = AnyEvent->io (fh => $fh, poll => "r", cb => sub { $wself->_recv }); |
769 |
|
770 |
$self->_compile; |
771 |
|
772 |
$self |
773 |
} |
774 |
|
775 |
=item $resolver->parse_resolv_conv ($string) |
776 |
|
777 |
Parses the given string as if it were a F<resolv.conf> file. The following |
778 |
directives are supported (but not necessarily implemented). |
779 |
|
780 |
C<#>-style comments, C<nameserver>, C<domain>, C<search>, C<sortlist>, |
781 |
C<options> (C<timeout>, C<attempts>, C<ndots>). |
782 |
|
783 |
Everything else is silently ignored. |
784 |
|
785 |
=cut |
786 |
|
787 |
sub parse_resolv_conf { |
788 |
my ($self, $resolvconf) = @_; |
789 |
|
790 |
$self->{server} = []; |
791 |
$self->{search} = []; |
792 |
|
793 |
my $attempts; |
794 |
|
795 |
for (split /\n/, $resolvconf) { |
796 |
if (/^\s*#/) { |
797 |
# comment |
798 |
} elsif (/^\s*nameserver\s+(\S+)\s*$/i) { |
799 |
my $ip = $1; |
800 |
if (my $ipn = AnyEvent::Socket::parse_ip ($ip)) { |
801 |
push @{ $self->{server} }, $ipn; |
802 |
} else { |
803 |
warn "nameserver $ip invalid and ignored\n"; |
804 |
} |
805 |
} elsif (/^\s*domain\s+(\S*)\s+$/i) { |
806 |
$self->{search} = [$1]; |
807 |
} elsif (/^\s*search\s+(.*?)\s*$/i) { |
808 |
$self->{search} = [split /\s+/, $1]; |
809 |
} elsif (/^\s*sortlist\s+(.*?)\s*$/i) { |
810 |
# ignored, NYI |
811 |
} elsif (/^\s*options\s+(.*?)\s*$/i) { |
812 |
for (split /\s+/, $1) { |
813 |
if (/^timeout:(\d+)$/) { |
814 |
$self->{timeout} = [$1]; |
815 |
} elsif (/^attempts:(\d+)$/) { |
816 |
$attempts = $1; |
817 |
} elsif (/^ndots:(\d+)$/) { |
818 |
$self->{ndots} = $1; |
819 |
} else { |
820 |
# debug, rotate, no-check-names, inet6 |
821 |
} |
822 |
} |
823 |
} |
824 |
} |
825 |
|
826 |
$self->{timeout} = [($self->{timeout}[0]) x $attempts] |
827 |
if $attempts; |
828 |
|
829 |
$self->_compile; |
830 |
} |
831 |
|
832 |
=item $resolver->os_config |
833 |
|
834 |
Tries so load and parse F</etc/resolv.conf> on portable operating systems. Tries various |
835 |
egregious hacks on windows to force the DNS servers and searchlist out of the system. |
836 |
|
837 |
=cut |
838 |
|
839 |
sub os_config { |
840 |
my ($self) = @_; |
841 |
|
842 |
$self->{server} = []; |
843 |
$self->{search} = []; |
844 |
|
845 |
if (WIN32 || $^O =~ /cygwin/i) { |
846 |
no strict 'refs'; |
847 |
|
848 |
# there are many options to find the current nameservers etc. on windows |
849 |
# all of them don't work consistently: |
850 |
# - the registry thing needs separate code on win32 native vs. cygwin |
851 |
# - the registry layout differs between windows versions |
852 |
# - calling windows api functions doesn't work on cygwin |
853 |
# - ipconfig uses locale-specific messages |
854 |
|
855 |
# we use ipconfig parsing because, despite all it's brokenness, |
856 |
# it seems most stable in practise. |
857 |
# for good measure, we append a fallback nameserver to our list. |
858 |
|
859 |
if (open my $fh, "ipconfig /all |") { |
860 |
# parsing strategy: we go through the output and look for |
861 |
# :-lines with DNS in them. everything in those is regarded as |
862 |
# either a nameserver (if it parses as an ip address), or a suffix |
863 |
# (all else). |
864 |
|
865 |
my $dns; |
866 |
while (<$fh>) { |
867 |
if (s/^\s.*\bdns\b.*://i) { |
868 |
$dns = 1; |
869 |
} elsif (/^\S/ || /^\s[^:]{16,}: /) { |
870 |
$dns = 0; |
871 |
} |
872 |
if ($dns && /^\s*(\S+)\s*$/) { |
873 |
my $s = $1; |
874 |
$s =~ s/%\d+(?!\S)//; # get rid of scope id |
875 |
if (my $ipn = AnyEvent::Socket::parse_ip ($s)) { |
876 |
push @{ $self->{server} }, $ipn; |
877 |
} else { |
878 |
push @{ $self->{search} }, $s; |
879 |
} |
880 |
} |
881 |
} |
882 |
|
883 |
# always add one fallback server |
884 |
push @{ $self->{server} }, $DNS_FALLBACK[rand @DNS_FALLBACK]; |
885 |
|
886 |
$self->_compile; |
887 |
} |
888 |
} else { |
889 |
# try resolv.conf everywhere |
890 |
|
891 |
if (open my $fh, "</etc/resolv.conf") { |
892 |
local $/; |
893 |
$self->parse_resolv_conf (<$fh>); |
894 |
} |
895 |
} |
896 |
} |
897 |
|
898 |
sub _compile { |
899 |
my $self = shift; |
900 |
|
901 |
# we currently throw away all ipv6 nameservers, we do not yet support those |
902 |
|
903 |
my %search; $self->{search} = [grep 0 < length, grep !$search{$_}++, @{ $self->{search} }]; |
904 |
my %server; $self->{server} = [grep 4 == length, grep !$server{$_}++, @{ $self->{server} }]; |
905 |
|
906 |
unless (@{ $self->{server} }) { |
907 |
# use 127.0.0.1 by default, and one opendns nameserver as fallback |
908 |
$self->{server} = [v127.0.0.1, $DNS_FALLBACK[rand @DNS_FALLBACK]]; |
909 |
} |
910 |
|
911 |
my @retry; |
912 |
|
913 |
for my $timeout (@{ $self->{timeout} }) { |
914 |
for my $server (@{ $self->{server} }) { |
915 |
push @retry, [$server, $timeout]; |
916 |
} |
917 |
} |
918 |
|
919 |
$self->{retry} = \@retry; |
920 |
} |
921 |
|
922 |
sub _feed { |
923 |
my ($self, $res) = @_; |
924 |
|
925 |
$res = dns_unpack $res |
926 |
or return; |
927 |
|
928 |
my $id = $self->{id}{$res->{id}}; |
929 |
|
930 |
return unless ref $id; |
931 |
|
932 |
$NOW = time; |
933 |
$id->[1]->($res); |
934 |
} |
935 |
|
936 |
sub _recv { |
937 |
my ($self) = @_; |
938 |
|
939 |
# we ignore errors (often one gets port unreachable, but there is |
940 |
# no good way to take advantage of that. |
941 |
while (my $peer = recv $self->{fh}, my $res, 4096, 0) { |
942 |
my ($port, $host) = AnyEvent::Socket::unpack_sockaddr ($peer); |
943 |
|
944 |
return unless $port == 53 && grep $_ eq $host, @{ $self->{server} }; |
945 |
|
946 |
$self->_feed ($res); |
947 |
} |
948 |
} |
949 |
|
950 |
sub _free_id { |
951 |
my ($self, $id, $timeout) = @_; |
952 |
|
953 |
if ($timeout) { |
954 |
# we need to block the id for a while |
955 |
$self->{id}{$id} = 1; |
956 |
push @{ $self->{reuse_q} }, [$NOW + $self->{reuse}, $id]; |
957 |
} else { |
958 |
# we can quickly recycle the id |
959 |
delete $self->{id}{$id}; |
960 |
} |
961 |
|
962 |
--$self->{outstanding}; |
963 |
$self->_scheduler; |
964 |
} |
965 |
|
966 |
# execute a single request, involves sending it with timeouts to multiple servers |
967 |
sub _exec { |
968 |
my ($self, $req) = @_; |
969 |
|
970 |
my $retry; # of retries |
971 |
my $do_retry; |
972 |
|
973 |
$do_retry = sub { |
974 |
my $retry_cfg = $self->{retry}[$retry++] |
975 |
or do { |
976 |
# failure |
977 |
$self->_free_id ($req->[2], $retry > 1); |
978 |
undef $do_retry; return $req->[1]->(); |
979 |
}; |
980 |
|
981 |
my ($server, $timeout) = @$retry_cfg; |
982 |
|
983 |
$self->{id}{$req->[2]} = [AnyEvent->timer (after => $timeout, cb => sub { |
984 |
$NOW = time; |
985 |
|
986 |
# timeout, try next |
987 |
&$do_retry; |
988 |
}), sub { |
989 |
my ($res) = @_; |
990 |
|
991 |
if ($res->{tc}) { |
992 |
# success, but truncated, so use tcp |
993 |
AnyEvent::Socket::tcp_connect ((Socket::inet_ntoa $server), 53, sub { |
994 |
my ($fh) = @_ |
995 |
or return &$do_retry; |
996 |
|
997 |
my $handle = new AnyEvent::Handle |
998 |
fh => $fh, |
999 |
on_error => sub { |
1000 |
# failure, try next |
1001 |
&$do_retry; |
1002 |
}; |
1003 |
|
1004 |
$handle->push_write (pack "n/a", $req->[0]); |
1005 |
$handle->push_read (chunk => 2, sub { |
1006 |
$handle->unshift_read (chunk => (unpack "n", $_[1]), sub { |
1007 |
$self->_feed ($_[1]); |
1008 |
}); |
1009 |
}); |
1010 |
shutdown $fh, 1; |
1011 |
|
1012 |
}, sub { $timeout }); |
1013 |
|
1014 |
} else { |
1015 |
# success |
1016 |
$self->_free_id ($req->[2], $retry > 1); |
1017 |
undef $do_retry; return $req->[1]->($res); |
1018 |
} |
1019 |
}]; |
1020 |
|
1021 |
send $self->{fh}, $req->[0], 0, AnyEvent::Socket::pack_sockaddr (53, $server); |
1022 |
}; |
1023 |
|
1024 |
&$do_retry; |
1025 |
} |
1026 |
|
1027 |
sub _scheduler { |
1028 |
my ($self) = @_; |
1029 |
|
1030 |
$NOW = time; |
1031 |
|
1032 |
# first clear id reuse queue |
1033 |
delete $self->{id}{ (shift @{ $self->{reuse_q} })->[1] } |
1034 |
while @{ $self->{reuse_q} } && $self->{reuse_q}[0][0] <= $NOW; |
1035 |
|
1036 |
while ($self->{outstanding} < $self->{max_outstanding}) { |
1037 |
|
1038 |
if (@{ $self->{reuse_q} } >= 30000) { |
1039 |
# we ran out of ID's, wait a bit |
1040 |
$self->{reuse_to} ||= AnyEvent->timer (after => $self->{reuse_q}[0][0] - $NOW, cb => sub { |
1041 |
delete $self->{reuse_to}; |
1042 |
$self->_scheduler; |
1043 |
}); |
1044 |
last; |
1045 |
} |
1046 |
|
1047 |
my $req = shift @{ $self->{queue} } |
1048 |
or last; |
1049 |
|
1050 |
while () { |
1051 |
$req->[2] = int rand 65536; |
1052 |
last unless exists $self->{id}{$req->[2]}; |
1053 |
} |
1054 |
|
1055 |
++$self->{outstanding}; |
1056 |
$self->{id}{$req->[2]} = 1; |
1057 |
substr $req->[0], 0, 2, pack "n", $req->[2]; |
1058 |
|
1059 |
$self->_exec ($req); |
1060 |
} |
1061 |
} |
1062 |
|
1063 |
=item $resolver->request ($req, $cb->($res)) |
1064 |
|
1065 |
Sends a single request (a hash-ref formated as specified for |
1066 |
C<dns_pack>) to the configured nameservers including |
1067 |
retries. Calls the callback with the decoded response packet if a reply |
1068 |
was received, or no arguments on timeout. |
1069 |
|
1070 |
=cut |
1071 |
|
1072 |
sub request($$) { |
1073 |
my ($self, $req, $cb) = @_; |
1074 |
|
1075 |
push @{ $self->{queue} }, [dns_pack $req, $cb]; |
1076 |
$self->_scheduler; |
1077 |
} |
1078 |
|
1079 |
=item $resolver->resolve ($qname, $qtype, %options, $cb->($rcode, @rr)) |
1080 |
|
1081 |
Queries the DNS for the given domain name C<$qname> of type C<$qtype> (a |
1082 |
qtype of "*" is supported and means "any"). |
1083 |
|
1084 |
The callback will be invoked with a list of matching result records or |
1085 |
none on any error or if the name could not be found. |
1086 |
|
1087 |
CNAME chains (although illegal) are followed up to a length of 8. |
1088 |
|
1089 |
Note that this resolver is just a stub resolver: it requires a name server |
1090 |
supporting recursive queries, will not do any recursive queries itself and |
1091 |
is not secure when used against an untrusted name server. |
1092 |
|
1093 |
The following options are supported: |
1094 |
|
1095 |
=over 4 |
1096 |
|
1097 |
=item search => [$suffix...] |
1098 |
|
1099 |
Use the given search list (which might be empty), by appending each one |
1100 |
in turn to the C<$qname>. If this option is missing then the configured |
1101 |
C<ndots> and C<search> define its value. If the C<$qname> ends in a dot, |
1102 |
then the searchlist will be ignored. |
1103 |
|
1104 |
=item accept => [$type...] |
1105 |
|
1106 |
Lists the acceptable result types: only result types in this set will be |
1107 |
accepted and returned. The default includes the C<$qtype> and nothing |
1108 |
else. |
1109 |
|
1110 |
=item class => "class" |
1111 |
|
1112 |
Specify the query class ("in" for internet, "ch" for chaosnet and "hs" for |
1113 |
hesiod are the only ones making sense). The default is "in", of course. |
1114 |
|
1115 |
=back |
1116 |
|
1117 |
Examples: |
1118 |
|
1119 |
$res->resolve ("ruth.plan9.de", "a", sub { |
1120 |
warn Dumper [@_]; |
1121 |
}); |
1122 |
|
1123 |
[ |
1124 |
[ |
1125 |
'ruth.schmorp.de', |
1126 |
'a', |
1127 |
'in', |
1128 |
'129.13.162.95' |
1129 |
] |
1130 |
] |
1131 |
|
1132 |
$res->resolve ("test1.laendle", "*", |
1133 |
accept => ["a", "aaaa"], |
1134 |
sub { |
1135 |
warn Dumper [@_]; |
1136 |
} |
1137 |
); |
1138 |
|
1139 |
[ |
1140 |
[ |
1141 |
'test1.laendle', |
1142 |
'a', |
1143 |
'in', |
1144 |
'10.0.0.255' |
1145 |
], |
1146 |
[ |
1147 |
'test1.laendle', |
1148 |
'aaaa', |
1149 |
'in', |
1150 |
'3ffe:1900:4545:0002:0240:0000:0000:f7e1' |
1151 |
] |
1152 |
] |
1153 |
|
1154 |
=cut |
1155 |
|
1156 |
sub resolve($%) { |
1157 |
my $cb = pop; |
1158 |
my ($self, $qname, $qtype, %opt) = @_; |
1159 |
|
1160 |
my @search = $qname =~ s/\.$// |
1161 |
? "" |
1162 |
: $opt{search} |
1163 |
? @{ $opt{search} } |
1164 |
: ($qname =~ y/.//) >= $self->{ndots} |
1165 |
? ("", @{ $self->{search} }) |
1166 |
: (@{ $self->{search} }, ""); |
1167 |
|
1168 |
my $class = $opt{class} || "in"; |
1169 |
|
1170 |
my %atype = $opt{accept} |
1171 |
? map +($_ => 1), @{ $opt{accept} } |
1172 |
: ($qtype => 1); |
1173 |
|
1174 |
# advance in searchlist |
1175 |
my ($do_search, $do_req); |
1176 |
|
1177 |
$do_search = sub { |
1178 |
@search |
1179 |
or (undef $do_search), (undef $do_req), return $cb->(); |
1180 |
|
1181 |
(my $name = lc "$qname." . shift @search) =~ s/\.$//; |
1182 |
my $depth = 2; |
1183 |
|
1184 |
# advance in cname-chain |
1185 |
$do_req = sub { |
1186 |
$self->request ({ |
1187 |
rd => 1, |
1188 |
qd => [[$name, $qtype, $class]], |
1189 |
}, sub { |
1190 |
my ($res) = @_ |
1191 |
or return $do_search->(); |
1192 |
|
1193 |
my $cname; |
1194 |
|
1195 |
while () { |
1196 |
# results found? |
1197 |
my @rr = grep $name eq lc $_->[0] && ($atype{"*"} || $atype{$_->[1]}), @{ $res->{an} }; |
1198 |
|
1199 |
(undef $do_search), (undef $do_req), return $cb->(@rr) |
1200 |
if @rr; |
1201 |
|
1202 |
# see if there is a cname we can follow |
1203 |
my @rr = grep $name eq lc $_->[0] && $_->[1] eq "cname", @{ $res->{an} }; |
1204 |
|
1205 |
if (@rr) { |
1206 |
$depth-- |
1207 |
or return $do_search->(); # cname chain too long |
1208 |
|
1209 |
$cname = 1; |
1210 |
$name = $rr[0][3]; |
1211 |
|
1212 |
} elsif ($cname) { |
1213 |
# follow the cname |
1214 |
return $do_req->(); |
1215 |
|
1216 |
} else { |
1217 |
# no, not found anything |
1218 |
return $do_search->(); |
1219 |
} |
1220 |
} |
1221 |
}); |
1222 |
}; |
1223 |
|
1224 |
$do_req->(); |
1225 |
}; |
1226 |
|
1227 |
$do_search->(); |
1228 |
} |
1229 |
|
1230 |
use AnyEvent::Socket (); # circular dependency, so do not import anything and do it at the end |
1231 |
|
1232 |
1; |
1233 |
|
1234 |
=back |
1235 |
|
1236 |
=head1 AUTHOR |
1237 |
|
1238 |
Marc Lehmann <schmorp@schmorp.de> |
1239 |
http://home.schmorp.de/ |
1240 |
|
1241 |
=cut |
1242 |
|