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", sub { $cv->send (@_) }; |
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::Handle (); |
37 |
|
38 |
=item AnyEvent::DNS::addr $node, $service, $proto, $family, $type, $cb->([$family, $type, $proto, $sockaddr], ...) |
39 |
|
40 |
Tries to resolve the given nodename and service name into protocol families |
41 |
and sockaddr structures usable to connect to this node and service in a |
42 |
protocol-independent way. It works remotely similar to the getaddrinfo |
43 |
posix function. |
44 |
|
45 |
C<$node> is either an IPv4 or IPv6 address or a hostname, C<$service> is |
46 |
either a service name (port name from F</etc/services>) or a numerical |
47 |
port number. If both C<$node> and C<$service> are names, then SRV records |
48 |
will be consulted to find the real service, otherwise they will be |
49 |
used as-is. If you know that the service name is not in your services |
50 |
database, then you can specify the service in the format C<name=port> |
51 |
(e.g. C<http=80>). |
52 |
|
53 |
C<$proto> must be a protocol name, currently C<tcp>, C<udp> or |
54 |
C<sctp>. The default is C<tcp>. |
55 |
|
56 |
C<$family> must be either C<0> (meaning any protocol is OK), C<4> (use |
57 |
only IPv4) or C<6> (use only IPv6). This setting might be influenced by |
58 |
C<$ENV{PERL_ANYEVENT_PROTOCOLS}>. |
59 |
|
60 |
C<$type> must be C<SOCK_STREAM>, C<SOCK_DGRAM> or C<SOCK_SEQPACKET> (or |
61 |
C<undef> in which case it gets automatically chosen). |
62 |
|
63 |
The callback will receive zero or more array references that contain |
64 |
C<$family, $type, $proto> for use in C<socket> and a binary |
65 |
C<$sockaddr> for use in C<connect> (or C<bind>). |
66 |
|
67 |
The application should try these in the order given. |
68 |
|
69 |
Example: |
70 |
|
71 |
AnyEvent::DNS::addr "google.com", "http", 0, undef, undef, sub { ... }; |
72 |
|
73 |
=item AnyEvent::DNS::a $domain, $cb->(@addrs) |
74 |
|
75 |
Tries to resolve the given domain to IPv4 address(es). |
76 |
|
77 |
=item AnyEvent::DNS::aaaa $domain, $cb->(@addrs) |
78 |
|
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Tries to resolve the given domain to IPv6 address(es). |
80 |
|
81 |
=item AnyEvent::DNS::mx $domain, $cb->(@hostnames) |
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|
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Tries to resolve the given domain into a sorted (lower preference value |
84 |
first) list of domain names. |
85 |
|
86 |
=item AnyEvent::DNS::ns $domain, $cb->(@hostnames) |
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|
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Tries to resolve the given domain name into a list of name servers. |
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|
90 |
=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. |
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|
94 |
=item AnyEvent::DNS::srv $service, $proto, $domain, $cb->(@srv_rr) |
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|
96 |
Tries to resolve the given service, protocol and domain name into a list |
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of service records. |
98 |
|
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Each srv_rr is an array reference with the following contents: |
100 |
C<[$priority, $weight, $transport, $target]>. |
101 |
|
102 |
They will be sorted with lowest priority, highest weight first (TODO: |
103 |
should use the RFC algorithm to reorder same-priority records for weight). |
104 |
|
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Example: |
106 |
|
107 |
AnyEvent::DNS::srv "sip", "udp", "schmorp.de", sub { ... |
108 |
# @_ = ( [10, 10, 5060, "sip1.schmorp.de" ] ) |
109 |
|
110 |
=item AnyEvent::DNS::ptr $ipv4_or_6, $cb->(@hostnames) |
111 |
|
112 |
Tries to reverse-resolve the given IPv4 or IPv6 address (in textual form) |
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into it's hostname(s). |
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|
115 |
Example: |
116 |
|
117 |
AnyEvent::DNS::ptr "2001:500:2f::f", sub { print shift }; |
118 |
# => f.root-servers.net |
119 |
|
120 |
=item AnyEvent::DNS::any $domain, $cb->(@rrs) |
121 |
|
122 |
Tries to resolve the given domain and passes all resource records found to |
123 |
the callback. |
124 |
|
125 |
=cut |
126 |
|
127 |
sub resolver; |
128 |
|
129 |
sub a($$) { |
130 |
my ($domain, $cb) = @_; |
131 |
|
132 |
resolver->resolve ($domain => "a", sub { |
133 |
$cb->(map $_->[3], @_); |
134 |
}); |
135 |
} |
136 |
|
137 |
sub aaaa($$) { |
138 |
my ($domain, $cb) = @_; |
139 |
|
140 |
resolver->resolve ($domain => "aaaa", sub { |
141 |
$cb->(map $_->[3], @_); |
142 |
}); |
143 |
} |
144 |
|
145 |
sub mx($$) { |
146 |
my ($domain, $cb) = @_; |
147 |
|
148 |
resolver->resolve ($domain => "mx", sub { |
149 |
$cb->(map $_->[4], sort { $a->[3] <=> $b->[3] } @_); |
150 |
}); |
151 |
} |
152 |
|
153 |
sub ns($$) { |
154 |
my ($domain, $cb) = @_; |
155 |
|
156 |
resolver->resolve ($domain => "ns", sub { |
157 |
$cb->(map $_->[3], @_); |
158 |
}); |
159 |
} |
160 |
|
161 |
sub txt($$) { |
162 |
my ($domain, $cb) = @_; |
163 |
|
164 |
resolver->resolve ($domain => "txt", sub { |
165 |
$cb->(map $_->[3], @_); |
166 |
}); |
167 |
} |
168 |
|
169 |
sub srv($$$$) { |
170 |
my ($service, $proto, $domain, $cb) = @_; |
171 |
|
172 |
# todo, ask for any and check glue records |
173 |
resolver->resolve ("_$service._$proto.$domain" => "srv", sub { |
174 |
$cb->(map [@$_[3,4,5,6]], sort { $a->[3] <=> $b->[3] || $b->[4] <=> $a->[4] } @_); |
175 |
}); |
176 |
} |
177 |
|
178 |
sub ptr($$) { |
179 |
my ($ip, $cb) = @_; |
180 |
|
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$ip = AnyEvent::Socket::parse_ip ($ip) |
182 |
or return $cb->(); |
183 |
|
184 |
if (4 == length $ip) { |
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$ip = join ".", (reverse split /\./, $ip), "in-addr.arpa."; |
186 |
} else { |
187 |
$ip = join ".", (reverse split //, unpack "H*", $ip), "ip6.arpa."; |
188 |
} |
189 |
|
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resolver->resolve ($ip => "ptr", sub { |
191 |
$cb->(map $_->[3], @_); |
192 |
}); |
193 |
} |
194 |
|
195 |
sub any($$) { |
196 |
my ($domain, $cb) = @_; |
197 |
|
198 |
resolver->resolve ($domain => "*", $cb); |
199 |
} |
200 |
|
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############################################################################# |
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|
203 |
sub addr($$$$$$) { |
204 |
my ($node, $service, $proto, $family, $type, $cb) = @_; |
205 |
|
206 |
unless (&AnyEvent::Util::AF_INET6) { |
207 |
$family != 6 |
208 |
or return $cb->(); |
209 |
|
210 |
$family ||= 4; |
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} |
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|
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$cb->() if $family == 4 && !$AnyEvent::PROTOCOL{ipv4}; |
214 |
$cb->() if $family == 6 && !$AnyEvent::PROTOCOL{ipv6}; |
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|
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$family ||=4 unless $AnyEvent::PROTOCOL{ipv6}; |
217 |
$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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|
222 |
my $proton = (getprotobyname $proto)[2] |
223 |
or Carp::croak "$proto: protocol unknown"; |
224 |
|
225 |
my $port; |
226 |
|
227 |
if ($service =~ /^(\S+)=(\d+)$/) { |
228 |
($service, $port) = ($1, $2); |
229 |
} elsif ($service =~ /^\d+$/) { |
230 |
($service, $port) = (undef, $service); |
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} else { |
232 |
$port = (getservbyname $service, $proto)[2] |
233 |
or Carp::croak "$service/$proto: service unknown"; |
234 |
} |
235 |
|
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my @target = [$node, $port]; |
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|
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# resolve a records / provide sockaddr structures |
239 |
my $resolve = sub { |
240 |
my @res; |
241 |
my $cv = AnyEvent->condvar (cb => sub { |
242 |
$cb->( |
243 |
map $_->[2], |
244 |
sort { |
245 |
$AnyEvent::PROTOCOL{$a->[1]} <=> $AnyEvent::PROTOCOL{$b->[1]} |
246 |
or $a->[0] <=> $b->[0] |
247 |
} |
248 |
@res |
249 |
) |
250 |
}); |
251 |
|
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$cv->begin; |
253 |
for my $idx (0 .. $#target) { |
254 |
my ($node, $port) = @{ $target[$idx] }; |
255 |
|
256 |
if (my $noden = AnyEvent::Socket::parse_ip ($node)) { |
257 |
if (4 == length $noden && $family != 6) { |
258 |
push @res, [$idx, "ipv4", [AF_INET, $type, $proton, |
259 |
AnyEvent::Socket::pack_sockaddr ($port, $noden)]] |
260 |
} |
261 |
|
262 |
if (16 == length $noden && $family != 4) { |
263 |
push @res, [$idx, "ipv6", [&AnyEvent::Util::AF_INET6, $type, $proton, |
264 |
AnyEvent::Socket::pack_sockaddr ( $port, $noden)]] |
265 |
} |
266 |
} else { |
267 |
# ipv4 |
268 |
if ($family != 6) { |
269 |
$cv->begin; |
270 |
a $node, sub { |
271 |
push @res, [$idx, "ipv4", [AF_INET, $type, $proton, |
272 |
AnyEvent::Socket::pack_sockaddr ($port, AnyEvent::Socket::parse_ipv4 ($_))]] |
273 |
for @_; |
274 |
$cv->end; |
275 |
}; |
276 |
} |
277 |
|
278 |
# ipv6 |
279 |
if ($family != 4) { |
280 |
$cv->begin; |
281 |
aaaa $node, sub { |
282 |
push @res, [$idx, "ipv6", [&AnyEvent::Socket::AF_INET6, $type, $proton, |
283 |
AnyEvent::Socket::pack_sockaddr ($port, AnyEvent::Socket::parse_ipv6 ($_))]] |
284 |
for @_; |
285 |
$cv->end; |
286 |
}; |
287 |
} |
288 |
} |
289 |
} |
290 |
$cv->end; |
291 |
}; |
292 |
|
293 |
# try srv records, if applicable |
294 |
if ($node eq "localhost") { |
295 |
@target = (["127.0.0.1", $port], ["::1", $port]); |
296 |
&$resolve; |
297 |
} elsif (defined $service && !AnyEvent::Socket::parse_ip ($node)) { |
298 |
srv $service, $proto, $node, sub { |
299 |
my (@srv) = @_; |
300 |
|
301 |
# no srv records, continue traditionally |
302 |
@srv |
303 |
or return &$resolve; |
304 |
|
305 |
# only srv record has "." => abort |
306 |
$srv[0][2] ne "." || $#srv |
307 |
or return $cb->(); |
308 |
|
309 |
# use srv records then |
310 |
@target = map ["$_->[3].", $_->[2]], |
311 |
grep $_->[3] ne ".", |
312 |
@srv; |
313 |
|
314 |
&$resolve; |
315 |
}; |
316 |
} else { |
317 |
&$resolve; |
318 |
} |
319 |
} |
320 |
|
321 |
############################################################################# |
322 |
|
323 |
=back |
324 |
|
325 |
=head2 LOW-LEVEL DNS EN-/DECODING FUNCTIONS |
326 |
|
327 |
=over 4 |
328 |
|
329 |
=item $AnyEvent::DNS::EDNS0 |
330 |
|
331 |
This variable decides whether dns_pack automatically enables EDNS0 |
332 |
support. By default, this is disabled (C<0>), unless overridden by |
333 |
C<$ENV{PERL_ANYEVENT_EDNS0>), but when set to C<1>, AnyEvent::DNS will use |
334 |
EDNS0 in all requests. |
335 |
|
336 |
=cut |
337 |
|
338 |
our $EDNS0 = $ENV{PERL_ANYEVENT_EDNS0} * 1; # set to 1 to enable (partial) edns0 |
339 |
|
340 |
our %opcode_id = ( |
341 |
query => 0, |
342 |
iquery => 1, |
343 |
status => 2, |
344 |
notify => 4, |
345 |
update => 5, |
346 |
map +($_ => $_), 3, 6..15 |
347 |
); |
348 |
|
349 |
our %opcode_str = reverse %opcode_id; |
350 |
|
351 |
our %rcode_id = ( |
352 |
noerror => 0, |
353 |
formerr => 1, |
354 |
servfail => 2, |
355 |
nxdomain => 3, |
356 |
notimp => 4, |
357 |
refused => 5, |
358 |
yxdomain => 6, # Name Exists when it should not [RFC 2136] |
359 |
yxrrset => 7, # RR Set Exists when it should not [RFC 2136] |
360 |
nxrrset => 8, # RR Set that should exist does not [RFC 2136] |
361 |
notauth => 9, # Server Not Authoritative for zone [RFC 2136] |
362 |
notzone => 10, # Name not contained in zone [RFC 2136] |
363 |
# EDNS0 16 BADVERS Bad OPT Version [RFC 2671] |
364 |
# EDNS0 16 BADSIG TSIG Signature Failure [RFC 2845] |
365 |
# EDNS0 17 BADKEY Key not recognized [RFC 2845] |
366 |
# EDNS0 18 BADTIME Signature out of time window [RFC 2845] |
367 |
# EDNS0 19 BADMODE Bad TKEY Mode [RFC 2930] |
368 |
# EDNS0 20 BADNAME Duplicate key name [RFC 2930] |
369 |
# EDNS0 21 BADALG Algorithm not supported [RFC 2930] |
370 |
map +($_ => $_), 11..15 |
371 |
); |
372 |
|
373 |
our %rcode_str = reverse %rcode_id; |
374 |
|
375 |
our %type_id = ( |
376 |
a => 1, |
377 |
ns => 2, |
378 |
md => 3, |
379 |
mf => 4, |
380 |
cname => 5, |
381 |
soa => 6, |
382 |
mb => 7, |
383 |
mg => 8, |
384 |
mr => 9, |
385 |
null => 10, |
386 |
wks => 11, |
387 |
ptr => 12, |
388 |
hinfo => 13, |
389 |
minfo => 14, |
390 |
mx => 15, |
391 |
txt => 16, |
392 |
aaaa => 28, |
393 |
srv => 33, |
394 |
opt => 41, |
395 |
spf => 99, |
396 |
tkey => 249, |
397 |
tsig => 250, |
398 |
ixfr => 251, |
399 |
axfr => 252, |
400 |
mailb => 253, |
401 |
"*" => 255, |
402 |
); |
403 |
|
404 |
our %type_str = reverse %type_id; |
405 |
|
406 |
our %class_id = ( |
407 |
in => 1, |
408 |
ch => 3, |
409 |
hs => 4, |
410 |
none => 254, |
411 |
"*" => 255, |
412 |
); |
413 |
|
414 |
our %class_str = reverse %class_id; |
415 |
|
416 |
# names MUST have a trailing dot |
417 |
sub _enc_qname($) { |
418 |
pack "(C/a*)*", (split /\./, shift), "" |
419 |
} |
420 |
|
421 |
sub _enc_qd() { |
422 |
(_enc_qname $_->[0]) . pack "nn", |
423 |
($_->[1] > 0 ? $_->[1] : $type_id {$_->[1]}), |
424 |
($_->[2] > 0 ? $_->[2] : $class_id{$_->[2] || "in"}) |
425 |
} |
426 |
|
427 |
sub _enc_rr() { |
428 |
die "encoding of resource records is not supported"; |
429 |
} |
430 |
|
431 |
=item $pkt = AnyEvent::DNS::dns_pack $dns |
432 |
|
433 |
Packs a perl data structure into a DNS packet. Reading RFC1034 is strongly |
434 |
recommended, then everything will be totally clear. Or maybe not. |
435 |
|
436 |
Resource records are not yet encodable. |
437 |
|
438 |
Examples: |
439 |
|
440 |
# very simple request, using lots of default values: |
441 |
{ rd => 1, qd => [ [ "host.domain", "a"] ] } |
442 |
|
443 |
# more complex example, showing how flags etc. are named: |
444 |
|
445 |
{ |
446 |
id => 10000, |
447 |
op => "query", |
448 |
rc => "nxdomain", |
449 |
|
450 |
# flags |
451 |
qr => 1, |
452 |
aa => 0, |
453 |
tc => 0, |
454 |
rd => 0, |
455 |
ra => 0, |
456 |
ad => 0, |
457 |
cd => 0, |
458 |
|
459 |
qd => [@rr], # query section |
460 |
an => [@rr], # answer section |
461 |
ns => [@rr], # authority section |
462 |
ar => [@rr], # additional records section |
463 |
} |
464 |
|
465 |
=cut |
466 |
|
467 |
sub dns_pack($) { |
468 |
my ($req) = @_; |
469 |
|
470 |
pack "nn nnnn a* a* a* a* a*", |
471 |
$req->{id}, |
472 |
|
473 |
! !$req->{qr} * 0x8000 |
474 |
+ $opcode_id{$req->{op}} * 0x0800 |
475 |
+ ! !$req->{aa} * 0x0400 |
476 |
+ ! !$req->{tc} * 0x0200 |
477 |
+ ! !$req->{rd} * 0x0100 |
478 |
+ ! !$req->{ra} * 0x0080 |
479 |
+ ! !$req->{ad} * 0x0020 |
480 |
+ ! !$req->{cd} * 0x0010 |
481 |
+ $rcode_id{$req->{rc}} * 0x0001, |
482 |
|
483 |
scalar @{ $req->{qd} || [] }, |
484 |
scalar @{ $req->{an} || [] }, |
485 |
scalar @{ $req->{ns} || [] }, |
486 |
$EDNS0 + scalar @{ $req->{ar} || [] }, # include EDNS0 option here |
487 |
|
488 |
(join "", map _enc_qd, @{ $req->{qd} || [] }), |
489 |
(join "", map _enc_rr, @{ $req->{an} || [] }), |
490 |
(join "", map _enc_rr, @{ $req->{ns} || [] }), |
491 |
(join "", map _enc_rr, @{ $req->{ar} || [] }), |
492 |
|
493 |
($EDNS0 ? pack "C nnNn", 0, 41, 4096, 0, 0 : "") # EDNS0, 4kiB udp payload size |
494 |
} |
495 |
|
496 |
our $ofs; |
497 |
our $pkt; |
498 |
|
499 |
# bitches |
500 |
sub _dec_qname { |
501 |
my @res; |
502 |
my $redir; |
503 |
my $ptr = $ofs; |
504 |
my $cnt; |
505 |
|
506 |
while () { |
507 |
return undef if ++$cnt >= 256; # to avoid DoS attacks |
508 |
|
509 |
my $len = ord substr $pkt, $ptr++, 1; |
510 |
|
511 |
if ($len & 0xc0) { |
512 |
$ptr++; |
513 |
$ofs = $ptr if $ptr > $ofs; |
514 |
$ptr = (unpack "n", substr $pkt, $ptr - 2, 2) & 0x3fff; |
515 |
} elsif ($len) { |
516 |
push @res, substr $pkt, $ptr, $len; |
517 |
$ptr += $len; |
518 |
} else { |
519 |
$ofs = $ptr if $ptr > $ofs; |
520 |
return join ".", @res; |
521 |
} |
522 |
} |
523 |
} |
524 |
|
525 |
sub _dec_qd { |
526 |
my $qname = _dec_qname; |
527 |
my ($qt, $qc) = unpack "nn", substr $pkt, $ofs; $ofs += 4; |
528 |
[$qname, $type_str{$qt} || $qt, $class_str{$qc} || $qc] |
529 |
} |
530 |
|
531 |
our %dec_rr = ( |
532 |
1 => sub { join ".", unpack "C4", $_ }, # a |
533 |
2 => sub { local $ofs = $ofs - length; _dec_qname }, # ns |
534 |
5 => sub { local $ofs = $ofs - length; _dec_qname }, # cname |
535 |
6 => sub { |
536 |
local $ofs = $ofs - length; |
537 |
my $mname = _dec_qname; |
538 |
my $rname = _dec_qname; |
539 |
($mname, $rname, unpack "NNNNN", substr $pkt, $ofs) |
540 |
}, # soa |
541 |
11 => sub { ((join ".", unpack "C4", $_), unpack "C a*", substr $_, 4) }, # wks |
542 |
12 => sub { local $ofs = $ofs - length; _dec_qname }, # ptr |
543 |
13 => sub { unpack "C/a* C/a*", $_ }, # hinfo |
544 |
15 => sub { local $ofs = $ofs + 2 - length; ((unpack "n", $_), _dec_qname) }, # mx |
545 |
16 => sub { unpack "(C/a*)*", $_ }, # txt |
546 |
28 => sub { AnyEvent::Socket::format_ip ($_) }, # aaaa |
547 |
33 => sub { local $ofs = $ofs + 6 - length; ((unpack "nnn", $_), _dec_qname) }, # srv |
548 |
99 => sub { unpack "(C/a*)*", $_ }, # spf |
549 |
); |
550 |
|
551 |
sub _dec_rr { |
552 |
my $qname = _dec_qname; |
553 |
|
554 |
my ($rt, $rc, $ttl, $rdlen) = unpack "nn N n", substr $pkt, $ofs; $ofs += 10; |
555 |
local $_ = substr $pkt, $ofs, $rdlen; $ofs += $rdlen; |
556 |
|
557 |
[ |
558 |
$qname, |
559 |
$type_str{$rt} || $rt, |
560 |
$class_str{$rc} || $rc, |
561 |
($dec_rr{$rt} || sub { $_ })->(), |
562 |
] |
563 |
} |
564 |
|
565 |
=item $dns = AnyEvent::DNS::dns_unpack $pkt |
566 |
|
567 |
Unpacks a DNS packet into a perl data structure. |
568 |
|
569 |
Examples: |
570 |
|
571 |
# an unsuccessful reply |
572 |
{ |
573 |
'qd' => [ |
574 |
[ 'ruth.plan9.de.mach.uni-karlsruhe.de', '*', 'in' ] |
575 |
], |
576 |
'rc' => 'nxdomain', |
577 |
'ar' => [], |
578 |
'ns' => [ |
579 |
[ |
580 |
'uni-karlsruhe.de', |
581 |
'soa', |
582 |
'in', |
583 |
'netserv.rz.uni-karlsruhe.de', |
584 |
'hostmaster.rz.uni-karlsruhe.de', |
585 |
2008052201, 10800, 1800, 2592000, 86400 |
586 |
] |
587 |
], |
588 |
'tc' => '', |
589 |
'ra' => 1, |
590 |
'qr' => 1, |
591 |
'id' => 45915, |
592 |
'aa' => '', |
593 |
'an' => [], |
594 |
'rd' => 1, |
595 |
'op' => 'query' |
596 |
} |
597 |
|
598 |
# a successful reply |
599 |
|
600 |
{ |
601 |
'qd' => [ [ 'www.google.de', 'a', 'in' ] ], |
602 |
'rc' => 0, |
603 |
'ar' => [ |
604 |
[ 'a.l.google.com', 'a', 'in', '209.85.139.9' ], |
605 |
[ 'b.l.google.com', 'a', 'in', '64.233.179.9' ], |
606 |
[ 'c.l.google.com', 'a', 'in', '64.233.161.9' ], |
607 |
], |
608 |
'ns' => [ |
609 |
[ 'l.google.com', 'ns', 'in', 'a.l.google.com' ], |
610 |
[ 'l.google.com', 'ns', 'in', 'b.l.google.com' ], |
611 |
], |
612 |
'tc' => '', |
613 |
'ra' => 1, |
614 |
'qr' => 1, |
615 |
'id' => 64265, |
616 |
'aa' => '', |
617 |
'an' => [ |
618 |
[ 'www.google.de', 'cname', 'in', 'www.google.com' ], |
619 |
[ 'www.google.com', 'cname', 'in', 'www.l.google.com' ], |
620 |
[ 'www.l.google.com', 'a', 'in', '66.249.93.104' ], |
621 |
[ 'www.l.google.com', 'a', 'in', '66.249.93.147' ], |
622 |
], |
623 |
'rd' => 1, |
624 |
'op' => 0 |
625 |
} |
626 |
|
627 |
=cut |
628 |
|
629 |
sub dns_unpack($) { |
630 |
local $pkt = shift; |
631 |
my ($id, $flags, $qd, $an, $ns, $ar) |
632 |
= unpack "nn nnnn A*", $pkt; |
633 |
|
634 |
local $ofs = 6 * 2; |
635 |
|
636 |
{ |
637 |
id => $id, |
638 |
qr => ! ! ($flags & 0x8000), |
639 |
aa => ! ! ($flags & 0x0400), |
640 |
tc => ! ! ($flags & 0x0200), |
641 |
rd => ! ! ($flags & 0x0100), |
642 |
ra => ! ! ($flags & 0x0080), |
643 |
ad => ! ! ($flags & 0x0020), |
644 |
cd => ! ! ($flags & 0x0010), |
645 |
op => $opcode_str{($flags & 0x001e) >> 11}, |
646 |
rc => $rcode_str{($flags & 0x000f)}, |
647 |
|
648 |
qd => [map _dec_qd, 1 .. $qd], |
649 |
an => [map _dec_rr, 1 .. $an], |
650 |
ns => [map _dec_rr, 1 .. $ns], |
651 |
ar => [map _dec_rr, 1 .. $ar], |
652 |
} |
653 |
} |
654 |
|
655 |
############################################################################# |
656 |
|
657 |
=back |
658 |
|
659 |
=head2 THE AnyEvent::DNS RESOLVER CLASS |
660 |
|
661 |
This is the class which does the actual protocol work. |
662 |
|
663 |
=over 4 |
664 |
|
665 |
=cut |
666 |
|
667 |
use Carp (); |
668 |
use Scalar::Util (); |
669 |
use Socket (); |
670 |
|
671 |
our $NOW; |
672 |
|
673 |
=item AnyEvent::DNS::resolver |
674 |
|
675 |
This function creates and returns a resolver that is ready to use and |
676 |
should mimic the default resolver for your system as good as possible. |
677 |
|
678 |
It only ever creates one resolver and returns this one on subsequent |
679 |
calls. |
680 |
|
681 |
Unless you have special needs, prefer this function over creating your own |
682 |
resolver object. |
683 |
|
684 |
=cut |
685 |
|
686 |
our $RESOLVER; |
687 |
|
688 |
sub resolver() { |
689 |
$RESOLVER || do { |
690 |
$RESOLVER = new AnyEvent::DNS; |
691 |
$RESOLVER->os_config; |
692 |
$RESOLVER |
693 |
} |
694 |
} |
695 |
|
696 |
=item $resolver = new AnyEvent::DNS key => value... |
697 |
|
698 |
Creates and returns a new resolver. |
699 |
|
700 |
The following options are supported: |
701 |
|
702 |
=over 4 |
703 |
|
704 |
=item server => [...] |
705 |
|
706 |
A list of server addresses (default: C<v127.0.0.1>) in network format (4 |
707 |
octets for IPv4, 16 octets for IPv6 - not yet supported). |
708 |
|
709 |
=item timeout => [...] |
710 |
|
711 |
A list of timeouts to use (also determines the number of retries). To make |
712 |
three retries with individual time-outs of 2, 5 and 5 seconds, use C<[2, |
713 |
5, 5]>, which is also the default. |
714 |
|
715 |
=item search => [...] |
716 |
|
717 |
The default search list of suffixes to append to a domain name (default: none). |
718 |
|
719 |
=item ndots => $integer |
720 |
|
721 |
The number of dots (default: C<1>) that a name must have so that the resolver |
722 |
tries to resolve the name without any suffixes first. |
723 |
|
724 |
=item max_outstanding => $integer |
725 |
|
726 |
Most name servers do not handle many parallel requests very well. This option |
727 |
limits the number of outstanding requests to C<$n> (default: C<10>), that means |
728 |
if you request more than this many requests, then the additional requests will be queued |
729 |
until some other requests have been resolved. |
730 |
|
731 |
=item reuse => $seconds |
732 |
|
733 |
The number of seconds (default: C<300>) that a query id cannot be re-used |
734 |
after a timeout. If there as no time-out then query id's can be reused |
735 |
immediately. |
736 |
|
737 |
=back |
738 |
|
739 |
=cut |
740 |
|
741 |
sub new { |
742 |
my ($class, %arg) = @_; |
743 |
|
744 |
socket my $fh, AF_INET, &Socket::SOCK_DGRAM, 0 |
745 |
or Carp::croak "socket: $!"; |
746 |
|
747 |
AnyEvent::Util::fh_nonblocking $fh, 1; |
748 |
|
749 |
my $self = bless { |
750 |
server => [v127.0.0.1], |
751 |
timeout => [2, 5, 5], |
752 |
search => [], |
753 |
ndots => 1, |
754 |
max_outstanding => 10, |
755 |
reuse => 300, # reuse id's after 5 minutes only, if possible |
756 |
%arg, |
757 |
fh => $fh, |
758 |
reuse_q => [], |
759 |
}, $class; |
760 |
|
761 |
# search should default to gethostname's domain |
762 |
# but perl lacks a good posix module |
763 |
|
764 |
Scalar::Util::weaken (my $wself = $self); |
765 |
$self->{rw} = AnyEvent->io (fh => $fh, poll => "r", cb => sub { $wself->_recv }); |
766 |
|
767 |
$self->_compile; |
768 |
|
769 |
$self |
770 |
} |
771 |
|
772 |
=item $resolver->parse_resolv_conv ($string) |
773 |
|
774 |
Parses the given string as if it were a F<resolv.conf> file. The following |
775 |
directives are supported (but not necessarily implemented). |
776 |
|
777 |
C<#>-style comments, C<nameserver>, C<domain>, C<search>, C<sortlist>, |
778 |
C<options> (C<timeout>, C<attempts>, C<ndots>). |
779 |
|
780 |
Everything else is silently ignored. |
781 |
|
782 |
=cut |
783 |
|
784 |
sub parse_resolv_conf { |
785 |
my ($self, $resolvconf) = @_; |
786 |
|
787 |
$self->{server} = []; |
788 |
$self->{search} = []; |
789 |
|
790 |
my $attempts; |
791 |
|
792 |
for (split /\n/, $resolvconf) { |
793 |
if (/^\s*#/) { |
794 |
# comment |
795 |
} elsif (/^\s*nameserver\s+(\S+)\s*$/i) { |
796 |
my $ip = $1; |
797 |
if (my $ipn = AnyEvent::Socket::parse_ip ($ip)) { |
798 |
push @{ $self->{server} }, $ipn; |
799 |
} else { |
800 |
warn "nameserver $ip invalid and ignored\n"; |
801 |
} |
802 |
} elsif (/^\s*domain\s+(\S*)\s+$/i) { |
803 |
$self->{search} = [$1]; |
804 |
} elsif (/^\s*search\s+(.*?)\s*$/i) { |
805 |
$self->{search} = [split /\s+/, $1]; |
806 |
} elsif (/^\s*sortlist\s+(.*?)\s*$/i) { |
807 |
# ignored, NYI |
808 |
} elsif (/^\s*options\s+(.*?)\s*$/i) { |
809 |
for (split /\s+/, $1) { |
810 |
if (/^timeout:(\d+)$/) { |
811 |
$self->{timeout} = [$1]; |
812 |
} elsif (/^attempts:(\d+)$/) { |
813 |
$attempts = $1; |
814 |
} elsif (/^ndots:(\d+)$/) { |
815 |
$self->{ndots} = $1; |
816 |
} else { |
817 |
# debug, rotate, no-check-names, inet6 |
818 |
} |
819 |
} |
820 |
} |
821 |
} |
822 |
|
823 |
$self->{timeout} = [($self->{timeout}[0]) x $attempts] |
824 |
if $attempts; |
825 |
|
826 |
$self->_compile; |
827 |
} |
828 |
|
829 |
=item $resolver->os_config |
830 |
|
831 |
Tries so load and parse F</etc/resolv.conf> on portable operating systems. Tries various |
832 |
egregious hacks on windows to force the DNS servers and searchlist out of the system. |
833 |
|
834 |
=cut |
835 |
|
836 |
sub os_config { |
837 |
my ($self) = @_; |
838 |
|
839 |
if ($^O =~ /mswin32|cygwin/i) { |
840 |
# yeah, it suxx... lets hope DNS is DNS in all locales |
841 |
|
842 |
if (open my $fh, "ipconfig /all |") { |
843 |
delete $self->{server}; |
844 |
delete $self->{search}; |
845 |
|
846 |
while (<$fh>) { |
847 |
# first DNS.* is suffix list |
848 |
if (/^\s*DNS/) { |
849 |
while (/\s+([[:alnum:].\-]+)\s*$/) { |
850 |
push @{ $self->{search} }, $1; |
851 |
$_ = <$fh>; |
852 |
} |
853 |
last; |
854 |
} |
855 |
} |
856 |
|
857 |
while (<$fh>) { |
858 |
# second DNS.* is server address list |
859 |
if (/^\s*DNS/) { |
860 |
while (/\s+(\d+\.\d+\.\d+\.\d+)\s*$/) { |
861 |
my $ipn = AnyEvent::Socket::parse_ip ("$1"); # "" is necessary here, apparently |
862 |
push @{ $self->{server} }, $ipn |
863 |
if $ipn; |
864 |
$_ = <$fh>; |
865 |
} |
866 |
last; |
867 |
} |
868 |
} |
869 |
|
870 |
$self->_compile; |
871 |
} |
872 |
} else { |
873 |
# try resolv.conf everywhere |
874 |
|
875 |
if (open my $fh, "</etc/resolv.conf") { |
876 |
local $/; |
877 |
$self->parse_resolv_conf (<$fh>); |
878 |
} |
879 |
} |
880 |
} |
881 |
|
882 |
sub _compile { |
883 |
my $self = shift; |
884 |
|
885 |
my @retry; |
886 |
|
887 |
for my $timeout (@{ $self->{timeout} }) { |
888 |
for my $server (@{ $self->{server} }) { |
889 |
push @retry, [$server, $timeout]; |
890 |
} |
891 |
} |
892 |
|
893 |
$self->{retry} = \@retry; |
894 |
} |
895 |
|
896 |
sub _feed { |
897 |
my ($self, $res) = @_; |
898 |
|
899 |
$res = dns_unpack $res |
900 |
or return; |
901 |
|
902 |
my $id = $self->{id}{$res->{id}}; |
903 |
|
904 |
return unless ref $id; |
905 |
|
906 |
$NOW = time; |
907 |
$id->[1]->($res); |
908 |
} |
909 |
|
910 |
sub _recv { |
911 |
my ($self) = @_; |
912 |
|
913 |
while (my $peer = recv $self->{fh}, my $res, 4096, 0) { |
914 |
my ($port, $host) = AnyEvent::Socket::unpack_sockaddr ($peer); |
915 |
|
916 |
return unless $port == 53 && grep $_ eq $host, @{ $self->{server} }; |
917 |
|
918 |
$self->_feed ($res); |
919 |
} |
920 |
} |
921 |
|
922 |
sub _free_id { |
923 |
my ($self, $id, $timeout) = @_; |
924 |
|
925 |
if ($timeout) { |
926 |
# we need to block the id for a while |
927 |
$self->{id}{$id} = 1; |
928 |
push @{ $self->{reuse_q} }, [$NOW + $self->{reuse}, $id]; |
929 |
} else { |
930 |
# we can quickly recycle the id |
931 |
delete $self->{id}{$id}; |
932 |
} |
933 |
|
934 |
--$self->{outstanding}; |
935 |
$self->_scheduler; |
936 |
} |
937 |
|
938 |
# execute a single request, involves sending it with timeouts to multiple servers |
939 |
sub _exec { |
940 |
my ($self, $req) = @_; |
941 |
|
942 |
my $retry; # of retries |
943 |
my $do_retry; |
944 |
|
945 |
$do_retry = sub { |
946 |
my $retry_cfg = $self->{retry}[$retry++] |
947 |
or do { |
948 |
# failure |
949 |
$self->_free_id ($req->[2], $retry > 1); |
950 |
undef $do_retry; return $req->[1]->(); |
951 |
}; |
952 |
|
953 |
my ($server, $timeout) = @$retry_cfg; |
954 |
|
955 |
$self->{id}{$req->[2]} = [AnyEvent->timer (after => $timeout, cb => sub { |
956 |
$NOW = time; |
957 |
|
958 |
# timeout, try next |
959 |
&$do_retry; |
960 |
}), sub { |
961 |
my ($res) = @_; |
962 |
|
963 |
if ($res->{tc}) { |
964 |
# success, but truncated, so use tcp |
965 |
AnyEvent::Socket::tcp_connect ((Socket::inet_ntoa $server), 53, sub { |
966 |
my ($fh) = @_ |
967 |
or return &$do_retry; |
968 |
|
969 |
my $handle = new AnyEvent::Handle |
970 |
fh => $fh, |
971 |
on_error => sub { |
972 |
# failure, try next |
973 |
&$do_retry; |
974 |
}; |
975 |
|
976 |
$handle->push_write (pack "n/a", $req->[0]); |
977 |
$handle->push_read (chunk => 2, sub { |
978 |
$handle->unshift_read (chunk => (unpack "n", $_[1]), sub { |
979 |
$self->_feed ($_[1]); |
980 |
}); |
981 |
}); |
982 |
shutdown $fh, 1; |
983 |
|
984 |
}, sub { $timeout }); |
985 |
|
986 |
} else { |
987 |
# success |
988 |
$self->_free_id ($req->[2], $retry > 1); |
989 |
undef $do_retry; return $req->[1]->($res); |
990 |
} |
991 |
}]; |
992 |
|
993 |
send $self->{fh}, $req->[0], 0, AnyEvent::Socket::pack_sockaddr (53, $server); |
994 |
}; |
995 |
|
996 |
&$do_retry; |
997 |
} |
998 |
|
999 |
sub _scheduler { |
1000 |
my ($self) = @_; |
1001 |
|
1002 |
$NOW = time; |
1003 |
|
1004 |
# first clear id reuse queue |
1005 |
delete $self->{id}{ (shift @{ $self->{reuse_q} })->[1] } |
1006 |
while @{ $self->{reuse_q} } && $self->{reuse_q}[0][0] <= $NOW; |
1007 |
|
1008 |
while ($self->{outstanding} < $self->{max_outstanding}) { |
1009 |
|
1010 |
if (@{ $self->{reuse_q} } >= 30000) { |
1011 |
# we ran out of ID's, wait a bit |
1012 |
$self->{reuse_to} ||= AnyEvent->timer (after => $self->{reuse_q}[0][0] - $NOW, cb => sub { |
1013 |
delete $self->{reuse_to}; |
1014 |
$self->_scheduler; |
1015 |
}); |
1016 |
last; |
1017 |
} |
1018 |
|
1019 |
my $req = shift @{ $self->{queue} } |
1020 |
or last; |
1021 |
|
1022 |
while () { |
1023 |
$req->[2] = int rand 65536; |
1024 |
last unless exists $self->{id}{$req->[2]}; |
1025 |
} |
1026 |
|
1027 |
++$self->{outstanding}; |
1028 |
$self->{id}{$req->[2]} = 1; |
1029 |
substr $req->[0], 0, 2, pack "n", $req->[2]; |
1030 |
|
1031 |
$self->_exec ($req); |
1032 |
} |
1033 |
} |
1034 |
|
1035 |
=item $resolver->request ($req, $cb->($res)) |
1036 |
|
1037 |
Sends a single request (a hash-ref formated as specified for |
1038 |
C<dns_pack>) to the configured nameservers including |
1039 |
retries. Calls the callback with the decoded response packet if a reply |
1040 |
was received, or no arguments on timeout. |
1041 |
|
1042 |
=cut |
1043 |
|
1044 |
sub request($$) { |
1045 |
my ($self, $req, $cb) = @_; |
1046 |
|
1047 |
push @{ $self->{queue} }, [dns_pack $req, $cb]; |
1048 |
$self->_scheduler; |
1049 |
} |
1050 |
|
1051 |
=item $resolver->resolve ($qname, $qtype, %options, $cb->($rcode, @rr)) |
1052 |
|
1053 |
Queries the DNS for the given domain name C<$qname> of type C<$qtype> (a |
1054 |
qtype of "*" is supported and means "any"). |
1055 |
|
1056 |
The callback will be invoked with a list of matching result records or |
1057 |
none on any error or if the name could not be found. |
1058 |
|
1059 |
CNAME chains (although illegal) are followed up to a length of 8. |
1060 |
|
1061 |
Note that this resolver is just a stub resolver: it requires a name server |
1062 |
supporting recursive queries, will not do any recursive queries itself and |
1063 |
is not secure when used against an untrusted name server. |
1064 |
|
1065 |
The following options are supported: |
1066 |
|
1067 |
=over 4 |
1068 |
|
1069 |
=item search => [$suffix...] |
1070 |
|
1071 |
Use the given search list (which might be empty), by appending each one |
1072 |
in turn to the C<$qname>. If this option is missing then the configured |
1073 |
C<ndots> and C<search> define its value. If the C<$qname> ends in a dot, |
1074 |
then the searchlist will be ignored. |
1075 |
|
1076 |
=item accept => [$type...] |
1077 |
|
1078 |
Lists the acceptable result types: only result types in this set will be |
1079 |
accepted and returned. The default includes the C<$qtype> and nothing |
1080 |
else. |
1081 |
|
1082 |
=item class => "class" |
1083 |
|
1084 |
Specify the query class ("in" for internet, "ch" for chaosnet and "hs" for |
1085 |
hesiod are the only ones making sense). The default is "in", of course. |
1086 |
|
1087 |
=back |
1088 |
|
1089 |
Examples: |
1090 |
|
1091 |
$res->resolve ("ruth.plan9.de", "a", sub { |
1092 |
warn Dumper [@_]; |
1093 |
}); |
1094 |
|
1095 |
[ |
1096 |
[ |
1097 |
'ruth.schmorp.de', |
1098 |
'a', |
1099 |
'in', |
1100 |
'129.13.162.95' |
1101 |
] |
1102 |
] |
1103 |
|
1104 |
$res->resolve ("test1.laendle", "*", |
1105 |
accept => ["a", "aaaa"], |
1106 |
sub { |
1107 |
warn Dumper [@_]; |
1108 |
} |
1109 |
); |
1110 |
|
1111 |
[ |
1112 |
[ |
1113 |
'test1.laendle', |
1114 |
'a', |
1115 |
'in', |
1116 |
'10.0.0.255' |
1117 |
], |
1118 |
[ |
1119 |
'test1.laendle', |
1120 |
'aaaa', |
1121 |
'in', |
1122 |
'3ffe:1900:4545:0002:0240:0000:0000:f7e1' |
1123 |
] |
1124 |
] |
1125 |
|
1126 |
=cut |
1127 |
|
1128 |
sub resolve($%) { |
1129 |
my $cb = pop; |
1130 |
my ($self, $qname, $qtype, %opt) = @_; |
1131 |
|
1132 |
my @search = $qname =~ s/\.$// |
1133 |
? "" |
1134 |
: $opt{search} |
1135 |
? @{ $opt{search} } |
1136 |
: ($qname =~ y/.//) >= $self->{ndots} |
1137 |
? ("", @{ $self->{search} }) |
1138 |
: (@{ $self->{search} }, ""); |
1139 |
|
1140 |
my $class = $opt{class} || "in"; |
1141 |
|
1142 |
my %atype = $opt{accept} |
1143 |
? map +($_ => 1), @{ $opt{accept} } |
1144 |
: ($qtype => 1); |
1145 |
|
1146 |
# advance in searchlist |
1147 |
my ($do_search, $do_req); |
1148 |
|
1149 |
$do_search = sub { |
1150 |
@search |
1151 |
or (undef $do_search), (undef $do_req), return $cb->(); |
1152 |
|
1153 |
(my $name = lc "$qname." . shift @search) =~ s/\.$//; |
1154 |
my $depth = 2; |
1155 |
|
1156 |
# advance in cname-chain |
1157 |
$do_req = sub { |
1158 |
$self->request ({ |
1159 |
rd => 1, |
1160 |
qd => [[$name, $qtype, $class]], |
1161 |
}, sub { |
1162 |
my ($res) = @_ |
1163 |
or return $do_search->(); |
1164 |
|
1165 |
my $cname; |
1166 |
|
1167 |
while () { |
1168 |
# results found? |
1169 |
my @rr = grep $name eq lc $_->[0] && ($atype{"*"} || $atype{$_->[1]}), @{ $res->{an} }; |
1170 |
|
1171 |
(undef $do_search), (undef $do_req), return $cb->(@rr) |
1172 |
if @rr; |
1173 |
|
1174 |
# see if there is a cname we can follow |
1175 |
my @rr = grep $name eq lc $_->[0] && $_->[1] eq "cname", @{ $res->{an} }; |
1176 |
|
1177 |
if (@rr) { |
1178 |
$depth-- |
1179 |
or return $do_search->(); # cname chain too long |
1180 |
|
1181 |
$cname = 1; |
1182 |
$name = $rr[0][3]; |
1183 |
|
1184 |
} elsif ($cname) { |
1185 |
# follow the cname |
1186 |
return $do_req->(); |
1187 |
|
1188 |
} else { |
1189 |
# no, not found anything |
1190 |
return $do_search->(); |
1191 |
} |
1192 |
} |
1193 |
}); |
1194 |
}; |
1195 |
|
1196 |
$do_req->(); |
1197 |
}; |
1198 |
|
1199 |
$do_search->(); |
1200 |
} |
1201 |
|
1202 |
use AnyEvent::Socket (); # circular dependency, so do not import anything and do it at the end |
1203 |
|
1204 |
1; |
1205 |
|
1206 |
=back |
1207 |
|
1208 |
=head1 AUTHOR |
1209 |
|
1210 |
Marc Lehmann <schmorp@schmorp.de> |
1211 |
http://home.schmorp.de/ |
1212 |
|
1213 |
=cut |
1214 |
|