1 |
=head1 NAME |
2 |
|
3 |
AnyEvent::DNS - fully asynchronous DNS resolution |
4 |
|
5 |
=head1 SYNOPSIS |
6 |
|
7 |
use AnyEvent::DNS; |
8 |
|
9 |
=head1 DESCRIPTION |
10 |
|
11 |
This module offers both a number of DNS convenience functions as well |
12 |
as a fully asynchronous and high-performance pure-perl stub resolver. |
13 |
|
14 |
The stub resolver supports DNS over UDP, optional EDNS0 support for up to |
15 |
4kiB datagrams and automatically falls back to virtual circuit mode for |
16 |
large responses. |
17 |
|
18 |
=head2 CONVENIENCE FUNCTIONS |
19 |
|
20 |
=over 4 |
21 |
|
22 |
=cut |
23 |
|
24 |
package AnyEvent::DNS; |
25 |
|
26 |
no warnings; |
27 |
use strict; |
28 |
|
29 |
use AnyEvent::Util (); |
30 |
use AnyEvent::Handle (); |
31 |
|
32 |
=item AnyEvent::DNS::addr $node, $service, $family, $type, $cb->(@addrs) |
33 |
|
34 |
NOT YET IMPLEMENTED |
35 |
|
36 |
Tries to resolve the given nodename and service name into sockaddr |
37 |
structures usable to connect to this node and service in a |
38 |
protocol-independent way. It works similarly to the getaddrinfo posix |
39 |
function. |
40 |
|
41 |
Example: |
42 |
|
43 |
AnyEvent::DNS::addr "google.com", "http", AF_UNSPEC, SOCK_STREAM, sub { ... }; |
44 |
|
45 |
=item AnyEvent::DNS::a $domain, $cb->(@addrs) |
46 |
|
47 |
Tries to resolve the given domain to IPv4 address(es). |
48 |
|
49 |
=item AnyEvent::DNS::mx $domain, $cb->(@hostnames) |
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|
51 |
Tries to resolve the given domain into a sorted (lower preference value |
52 |
first) list of domain names. |
53 |
|
54 |
=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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|
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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. |
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|
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=item AnyEvent::DNS::srv $service, $proto, $domain, $cb->(@srv_rr) |
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|
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Tries to resolve the given service, protocol and domain name into a list |
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of service records. |
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|
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Each srv_rr is an arrayref with the following contents: |
68 |
C<[$priority, $weight, $transport, $target]>. |
69 |
|
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They will be sorted with lowest priority, highest weight first (TODO: |
71 |
should use the rfc algorithm to reorder same-priority records for weight). |
72 |
|
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Example: |
74 |
|
75 |
AnyEvent::DNS::srv "sip", "udp", "schmorp.de", sub { ... |
76 |
# @_ = ( [10, 10, 5060, "sip1.schmorp.de" ] ) |
77 |
|
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=item AnyEvent::DNS::ptr $ipv4_or_6, $cb->(@hostnames) |
79 |
|
80 |
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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|
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Requires the Socket6 module for IPv6 support. |
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|
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Example: |
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|
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AnyEvent::DNS::ptr "2001:500:2f::f", sub { print shift }; |
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# => f.root-servers.net |
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|
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=item AnyEvent::DNS::any $domain, $cb->(@rrs) |
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|
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Tries to resolve the given domain and passes all resource records found to |
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the callback. |
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|
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=cut |
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|
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sub resolver; |
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|
99 |
sub a($$) { |
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my ($domain, $cb) = @_; |
101 |
|
102 |
resolver->resolve ($domain => "a", sub { |
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$cb->(map $_->[3], @_); |
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}); |
105 |
} |
106 |
|
107 |
sub mx($$) { |
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my ($domain, $cb) = @_; |
109 |
|
110 |
resolver->resolve ($domain => "mx", sub { |
111 |
$cb->(map $_->[4], sort { $a->[3] <=> $b->[3] } @_); |
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}); |
113 |
} |
114 |
|
115 |
sub ns($$) { |
116 |
my ($domain, $cb) = @_; |
117 |
|
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resolver->resolve ($domain => "ns", sub { |
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$cb->(map $_->[3], @_); |
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}); |
121 |
} |
122 |
|
123 |
sub txt($$) { |
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my ($domain, $cb) = @_; |
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|
126 |
resolver->resolve ($domain => "txt", sub { |
127 |
$cb->(map $_->[3], @_); |
128 |
}); |
129 |
} |
130 |
|
131 |
sub srv($$$$) { |
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my ($service, $proto, $domain, $cb) = @_; |
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|
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# todo, ask for any and check glue records |
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resolver->resolve ("_$service._$proto.$domain" => "srv", sub { |
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$cb->(map [@$_[3,4,5,6]], sort { $a->[3] <=> $b->[3] || $b->[4] <=> $a->[4] } @_); |
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}); |
138 |
} |
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|
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sub ptr($$) { |
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my ($ip, $cb) = @_; |
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|
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my $name; |
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|
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if (AnyEvent::Util::dotted_quad $ip) { |
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$name = join ".", (reverse split /\./, $ip), "in-addr.arpa."; |
147 |
} else { |
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require Socket6; |
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$name = join ".", |
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(reverse split //, |
151 |
unpack "H*", Socket6::inet_pton (Socket::AF_INET6, $ip)), |
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"ip6.arpa."; |
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} |
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|
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resolver->resolve ($name => "ptr", sub { |
156 |
$cb->(map $_->[3], @_); |
157 |
}); |
158 |
} |
159 |
|
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sub any($$) { |
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my ($domain, $cb) = @_; |
162 |
|
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resolver->resolve ($domain => "*", $cb); |
164 |
} |
165 |
|
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=back |
167 |
|
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=head2 LOW-LEVEL DNS EN-/DECODING FUNCTIONS |
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|
170 |
=over 4 |
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|
172 |
=item $AnyEvent::DNS::EDNS0 |
173 |
|
174 |
This variable decides whether dns_pack automatically enables EDNS0 |
175 |
support. By default, this is disabled (C<0>), but when set to C<1>, |
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AnyEvent::DNS will use EDNS0 in all requests. |
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|
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=cut |
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|
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our $EDNS0 = 0; # set to 1 to enable (partial) edns0 |
181 |
|
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our %opcode_id = ( |
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query => 0, |
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iquery => 1, |
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status => 2, |
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notify => 4, |
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update => 5, |
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map +($_ => $_), 3, 6..15 |
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); |
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|
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our %opcode_str = reverse %opcode_id; |
192 |
|
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our %rcode_id = ( |
194 |
noerror => 0, |
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formerr => 1, |
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servfail => 2, |
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nxdomain => 3, |
198 |
notimp => 4, |
199 |
refused => 5, |
200 |
yxdomain => 6, # Name Exists when it should not [RFC 2136] |
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yxrrset => 7, # RR Set Exists when it should not [RFC 2136] |
202 |
nxrrset => 8, # RR Set that should exist does not [RFC 2136] |
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notauth => 9, # Server Not Authoritative for zone [RFC 2136] |
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notzone => 10, # Name not contained in zone [RFC 2136] |
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# EDNS0 16 BADVERS Bad OPT Version [RFC 2671] |
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# EDNS0 16 BADSIG TSIG Signature Failure [RFC 2845] |
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# EDNS0 17 BADKEY Key not recognized [RFC 2845] |
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# EDNS0 18 BADTIME Signature out of time window [RFC 2845] |
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# EDNS0 19 BADMODE Bad TKEY Mode [RFC 2930] |
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# EDNS0 20 BADNAME Duplicate key name [RFC 2930] |
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# EDNS0 21 BADALG Algorithm not supported [RFC 2930] |
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map +($_ => $_), 11..15 |
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); |
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|
215 |
our %rcode_str = reverse %rcode_id; |
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|
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our %type_id = ( |
218 |
a => 1, |
219 |
ns => 2, |
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md => 3, |
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mf => 4, |
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cname => 5, |
223 |
soa => 6, |
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mb => 7, |
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mg => 8, |
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mr => 9, |
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null => 10, |
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wks => 11, |
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ptr => 12, |
230 |
hinfo => 13, |
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minfo => 14, |
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mx => 15, |
233 |
txt => 16, |
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aaaa => 28, |
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srv => 33, |
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opt => 41, |
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spf => 99, |
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tkey => 249, |
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tsig => 250, |
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ixfr => 251, |
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axfr => 252, |
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mailb => 253, |
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"*" => 255, |
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); |
245 |
|
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our %type_str = reverse %type_id; |
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|
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our %class_id = ( |
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in => 1, |
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ch => 3, |
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hs => 4, |
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none => 254, |
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"*" => 255, |
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); |
255 |
|
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our %class_str = reverse %class_id; |
257 |
|
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# names MUST have a trailing dot |
259 |
sub _enc_qname($) { |
260 |
pack "(C/a)*", (split /\./, shift), "" |
261 |
} |
262 |
|
263 |
sub _enc_qd() { |
264 |
(_enc_qname $_->[0]) . pack "nn", |
265 |
($_->[1] > 0 ? $_->[1] : $type_id {$_->[1]}), |
266 |
($_->[2] > 0 ? $_->[2] : $class_id{$_->[2] || "in"}) |
267 |
} |
268 |
|
269 |
sub _enc_rr() { |
270 |
die "encoding of resource records is not supported"; |
271 |
} |
272 |
|
273 |
=item $pkt = AnyEvent::DNS::dns_pack $dns |
274 |
|
275 |
Packs a perl data structure into a DNS packet. Reading RFC1034 is strongly |
276 |
recommended, then everything will be totally clear. Or maybe not. |
277 |
|
278 |
Resource records are not yet encodable. |
279 |
|
280 |
Examples: |
281 |
|
282 |
# very simple request, using lots of default values: |
283 |
{ rd => 1, qd => [ [ "host.domain", "a"] ] } |
284 |
|
285 |
# more complex example, showing how flags etc. are named: |
286 |
|
287 |
{ |
288 |
id => 10000, |
289 |
op => "query", |
290 |
rc => "nxdomain", |
291 |
|
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# flags |
293 |
qr => 1, |
294 |
aa => 0, |
295 |
tc => 0, |
296 |
rd => 0, |
297 |
ra => 0, |
298 |
ad => 0, |
299 |
cd => 0, |
300 |
|
301 |
qd => [@rr], # query section |
302 |
an => [@rr], # answer section |
303 |
ns => [@rr], # authority section |
304 |
ar => [@rr], # additional records section |
305 |
} |
306 |
|
307 |
=cut |
308 |
|
309 |
sub dns_pack($) { |
310 |
my ($req) = @_; |
311 |
|
312 |
pack "nn nnnn a* a* a* a* a*", |
313 |
$req->{id}, |
314 |
|
315 |
! !$req->{qr} * 0x8000 |
316 |
+ $opcode_id{$req->{op}} * 0x0800 |
317 |
+ ! !$req->{aa} * 0x0400 |
318 |
+ ! !$req->{tc} * 0x0200 |
319 |
+ ! !$req->{rd} * 0x0100 |
320 |
+ ! !$req->{ra} * 0x0080 |
321 |
+ ! !$req->{ad} * 0x0020 |
322 |
+ ! !$req->{cd} * 0x0010 |
323 |
+ $rcode_id{$req->{rc}} * 0x0001, |
324 |
|
325 |
scalar @{ $req->{qd} || [] }, |
326 |
scalar @{ $req->{an} || [] }, |
327 |
scalar @{ $req->{ns} || [] }, |
328 |
$EDNS0 + scalar @{ $req->{ar} || [] }, # include EDNS0 option here |
329 |
|
330 |
(join "", map _enc_qd, @{ $req->{qd} || [] }), |
331 |
(join "", map _enc_rr, @{ $req->{an} || [] }), |
332 |
(join "", map _enc_rr, @{ $req->{ns} || [] }), |
333 |
(join "", map _enc_rr, @{ $req->{ar} || [] }), |
334 |
|
335 |
($EDNS0 ? pack "C nnNn", 0, 41, 4096, 0, 0 : "") # EDNS0, 4kiB udp payload size |
336 |
} |
337 |
|
338 |
our $ofs; |
339 |
our $pkt; |
340 |
|
341 |
# bitches |
342 |
sub _dec_qname { |
343 |
my @res; |
344 |
my $redir; |
345 |
my $ptr = $ofs; |
346 |
my $cnt; |
347 |
|
348 |
while () { |
349 |
return undef if ++$cnt >= 256; # to avoid DoS attacks |
350 |
|
351 |
my $len = ord substr $pkt, $ptr++, 1; |
352 |
|
353 |
if ($len & 0xc0) { |
354 |
$ptr++; |
355 |
$ofs = $ptr if $ptr > $ofs; |
356 |
$ptr = (unpack "n", substr $pkt, $ptr - 2, 2) & 0x3fff; |
357 |
} elsif ($len) { |
358 |
push @res, substr $pkt, $ptr, $len; |
359 |
$ptr += $len; |
360 |
} else { |
361 |
$ofs = $ptr if $ptr > $ofs; |
362 |
return join ".", @res; |
363 |
} |
364 |
} |
365 |
} |
366 |
|
367 |
sub _dec_qd { |
368 |
my $qname = _dec_qname; |
369 |
my ($qt, $qc) = unpack "nn", substr $pkt, $ofs; $ofs += 4; |
370 |
[$qname, $type_str{$qt} || $qt, $class_str{$qc} || $qc] |
371 |
} |
372 |
|
373 |
our %dec_rr = ( |
374 |
1 => sub { Socket::inet_ntoa $_ }, # a |
375 |
2 => sub { local $ofs = $ofs - length; _dec_qname }, # ns |
376 |
5 => sub { local $ofs = $ofs - length; _dec_qname }, # cname |
377 |
6 => sub { |
378 |
local $ofs = $ofs - length; |
379 |
my $mname = _dec_qname; |
380 |
my $rname = _dec_qname; |
381 |
($mname, $rname, unpack "NNNNN", substr $pkt, $ofs) |
382 |
}, # soa |
383 |
11 => sub { ((Socket::inet_aton substr $_, 0, 4), unpack "C a*", substr $_, 4) }, # wks |
384 |
12 => sub { local $ofs = $ofs - length; _dec_qname }, # ptr |
385 |
13 => sub { unpack "C/a C/a", $_ }, # hinfo |
386 |
15 => sub { local $ofs = $ofs + 2 - length; ((unpack "n", $_), _dec_qname) }, # mx |
387 |
16 => sub { unpack "(C/a)*", $_ }, # txt |
388 |
28 => sub { sprintf "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x", unpack "n8" }, # aaaa |
389 |
33 => sub { local $ofs = $ofs + 6 - length; ((unpack "nnn", $_), _dec_qname) }, # srv |
390 |
99 => sub { unpack "(C/a)*", $_ }, # spf |
391 |
); |
392 |
|
393 |
sub _dec_rr { |
394 |
my $qname = _dec_qname; |
395 |
|
396 |
my ($rt, $rc, $ttl, $rdlen) = unpack "nn N n", substr $pkt, $ofs; $ofs += 10; |
397 |
local $_ = substr $pkt, $ofs, $rdlen; $ofs += $rdlen; |
398 |
|
399 |
[ |
400 |
$qname, |
401 |
$type_str{$rt} || $rt, |
402 |
$class_str{$rc} || $rc, |
403 |
($dec_rr{$rt} || sub { $_ })->(), |
404 |
] |
405 |
} |
406 |
|
407 |
=item $dns = AnyEvent::DNS::dns_unpack $pkt |
408 |
|
409 |
Unpacks a DNS packet into a perl data structure. |
410 |
|
411 |
Examples: |
412 |
|
413 |
# an unsuccessful reply |
414 |
{ |
415 |
'qd' => [ |
416 |
[ 'ruth.plan9.de.mach.uni-karlsruhe.de', '*', 'in' ] |
417 |
], |
418 |
'rc' => 'nxdomain', |
419 |
'ar' => [], |
420 |
'ns' => [ |
421 |
[ |
422 |
'uni-karlsruhe.de', |
423 |
'soa', |
424 |
'in', |
425 |
'netserv.rz.uni-karlsruhe.de', |
426 |
'hostmaster.rz.uni-karlsruhe.de', |
427 |
2008052201, 10800, 1800, 2592000, 86400 |
428 |
] |
429 |
], |
430 |
'tc' => '', |
431 |
'ra' => 1, |
432 |
'qr' => 1, |
433 |
'id' => 45915, |
434 |
'aa' => '', |
435 |
'an' => [], |
436 |
'rd' => 1, |
437 |
'op' => 'query' |
438 |
} |
439 |
|
440 |
# a successful reply |
441 |
|
442 |
{ |
443 |
'qd' => [ [ 'www.google.de', 'a', 'in' ] ], |
444 |
'rc' => 0, |
445 |
'ar' => [ |
446 |
[ 'a.l.google.com', 'a', 'in', '209.85.139.9' ], |
447 |
[ 'b.l.google.com', 'a', 'in', '64.233.179.9' ], |
448 |
[ 'c.l.google.com', 'a', 'in', '64.233.161.9' ], |
449 |
], |
450 |
'ns' => [ |
451 |
[ 'l.google.com', 'ns', 'in', 'a.l.google.com' ], |
452 |
[ 'l.google.com', 'ns', 'in', 'b.l.google.com' ], |
453 |
], |
454 |
'tc' => '', |
455 |
'ra' => 1, |
456 |
'qr' => 1, |
457 |
'id' => 64265, |
458 |
'aa' => '', |
459 |
'an' => [ |
460 |
[ 'www.google.de', 'cname', 'in', 'www.google.com' ], |
461 |
[ 'www.google.com', 'cname', 'in', 'www.l.google.com' ], |
462 |
[ 'www.l.google.com', 'a', 'in', '66.249.93.104' ], |
463 |
[ 'www.l.google.com', 'a', 'in', '66.249.93.147' ], |
464 |
], |
465 |
'rd' => 1, |
466 |
'op' => 0 |
467 |
} |
468 |
|
469 |
=cut |
470 |
|
471 |
sub dns_unpack($) { |
472 |
local $pkt = shift; |
473 |
my ($id, $flags, $qd, $an, $ns, $ar) |
474 |
= unpack "nn nnnn A*", $pkt; |
475 |
|
476 |
local $ofs = 6 * 2; |
477 |
|
478 |
{ |
479 |
id => $id, |
480 |
qr => ! ! ($flags & 0x8000), |
481 |
aa => ! ! ($flags & 0x0400), |
482 |
tc => ! ! ($flags & 0x0200), |
483 |
rd => ! ! ($flags & 0x0100), |
484 |
ra => ! ! ($flags & 0x0080), |
485 |
ad => ! ! ($flags & 0x0020), |
486 |
cd => ! ! ($flags & 0x0010), |
487 |
op => $opcode_str{($flags & 0x001e) >> 11}, |
488 |
rc => $rcode_str{($flags & 0x000f)}, |
489 |
|
490 |
qd => [map _dec_qd, 1 .. $qd], |
491 |
an => [map _dec_rr, 1 .. $an], |
492 |
ns => [map _dec_rr, 1 .. $ns], |
493 |
ar => [map _dec_rr, 1 .. $ar], |
494 |
} |
495 |
} |
496 |
|
497 |
############################################################################# |
498 |
|
499 |
=back |
500 |
|
501 |
=head2 THE AnyEvent::DNS RESOLVER CLASS |
502 |
|
503 |
This is the class which does the actual protocol work. |
504 |
|
505 |
=over 4 |
506 |
|
507 |
=cut |
508 |
|
509 |
use Carp (); |
510 |
use Scalar::Util (); |
511 |
use Socket (); |
512 |
|
513 |
our $NOW; |
514 |
|
515 |
=item AnyEvent::DNS::resolver |
516 |
|
517 |
This function creates and returns a resolver that is ready to use and |
518 |
should mimic the default resolver for your system as good as possible. |
519 |
|
520 |
It only ever creates one resolver and returns this one on subsequent |
521 |
calls. |
522 |
|
523 |
Unless you have special needs, prefer this function over creating your own |
524 |
resolver object. |
525 |
|
526 |
=cut |
527 |
|
528 |
our $RESOLVER; |
529 |
|
530 |
sub resolver() { |
531 |
$RESOLVER || do { |
532 |
$RESOLVER = new AnyEvent::DNS; |
533 |
$RESOLVER->os_config; |
534 |
$RESOLVER |
535 |
} |
536 |
} |
537 |
|
538 |
=item $resolver = new AnyEvent::DNS key => value... |
539 |
|
540 |
Creates and returns a new resolver. |
541 |
|
542 |
The following options are supported: |
543 |
|
544 |
=over 4 |
545 |
|
546 |
=item server => [...] |
547 |
|
548 |
A list of server addressses (default: C<v127.0.0.1>) in network format (4 |
549 |
octets for IPv4, 16 octets for IPv6 - not yet supported). |
550 |
|
551 |
=item timeout => [...] |
552 |
|
553 |
A list of timeouts to use (also determines the number of retries). To make |
554 |
three retries with individual time-outs of 2, 5 and 5 seconds, use C<[2, |
555 |
5, 5]>, which is also the default. |
556 |
|
557 |
=item search => [...] |
558 |
|
559 |
The default search list of suffixes to append to a domain name (default: none). |
560 |
|
561 |
=item ndots => $integer |
562 |
|
563 |
The number of dots (default: C<1>) that a name must have so that the resolver |
564 |
tries to resolve the name without any suffixes first. |
565 |
|
566 |
=item max_outstanding => $integer |
567 |
|
568 |
Most name servers do not handle many parallel requests very well. This option |
569 |
limits the numbe rof outstanding requests to C<$n> (default: C<10>), that means |
570 |
if you request more than this many requests, then the additional requests will be queued |
571 |
until some other requests have been resolved. |
572 |
|
573 |
=item reuse => $seconds |
574 |
|
575 |
The number of seconds (default: C<60>) that a query id cannot be re-used |
576 |
after a request. Since AnyEvent::DNS will only allocate up to 30000 ID's |
577 |
at the same time, the long-term maximum number of requests per second is |
578 |
C<30000 / $seconds> (and thus C<500> requests/s by default). |
579 |
|
580 |
=back |
581 |
|
582 |
=cut |
583 |
|
584 |
sub new { |
585 |
my ($class, %arg) = @_; |
586 |
|
587 |
socket my $fh, &Socket::AF_INET, &Socket::SOCK_DGRAM, 0 |
588 |
or Carp::croak "socket: $!"; |
589 |
|
590 |
AnyEvent::Util::fh_nonblocking $fh, 1; |
591 |
|
592 |
my $self = bless { |
593 |
server => [v127.0.0.1], |
594 |
timeout => [2, 5, 5], |
595 |
search => [], |
596 |
ndots => 1, |
597 |
max_outstanding => 10, |
598 |
reuse => 60, # reuse id's after 5 minutes only, if possible |
599 |
%arg, |
600 |
fh => $fh, |
601 |
reuse_q => [], |
602 |
}, $class; |
603 |
|
604 |
# search should default to gethostname's domain |
605 |
# but perl lacks a good posix module |
606 |
|
607 |
Scalar::Util::weaken (my $wself = $self); |
608 |
$self->{rw} = AnyEvent->io (fh => $fh, poll => "r", cb => sub { $wself->_recv }); |
609 |
|
610 |
$self->_compile; |
611 |
|
612 |
$self |
613 |
} |
614 |
|
615 |
=item $resolver->parse_resolv_conv ($string) |
616 |
|
617 |
Parses the given string a sif it were a F<resolv.conf> file. The following |
618 |
directives are supported (but not neecssarily implemented). |
619 |
|
620 |
C<#>-style comments, C<nameserver>, C<domain>, C<search>, C<sortlist>, |
621 |
C<options> (C<timeout>, C<attempts>, C<ndots>). |
622 |
|
623 |
Everything else is silently ignored. |
624 |
|
625 |
=cut |
626 |
|
627 |
sub parse_resolv_conf { |
628 |
my ($self, $resolvconf) = @_; |
629 |
|
630 |
$self->{server} = []; |
631 |
$self->{search} = []; |
632 |
|
633 |
my $attempts; |
634 |
|
635 |
for (split /\n/, $resolvconf) { |
636 |
if (/^\s*#/) { |
637 |
# comment |
638 |
} elsif (/^\s*nameserver\s+(\S+)\s*$/i) { |
639 |
my $ip = $1; |
640 |
if (AnyEvent::Util::dotted_quad $ip) { |
641 |
push @{ $self->{server} }, AnyEvent::Util::socket_inet_aton $ip; |
642 |
} else { |
643 |
warn "nameserver $ip invalid and ignored\n"; |
644 |
} |
645 |
} elsif (/^\s*domain\s+(\S*)\s+$/i) { |
646 |
$self->{search} = [$1]; |
647 |
} elsif (/^\s*search\s+(.*?)\s*$/i) { |
648 |
$self->{search} = [split /\s+/, $1]; |
649 |
} elsif (/^\s*sortlist\s+(.*?)\s*$/i) { |
650 |
# ignored, NYI |
651 |
} elsif (/^\s*options\s+(.*?)\s*$/i) { |
652 |
for (split /\s+/, $1) { |
653 |
if (/^timeout:(\d+)$/) { |
654 |
$self->{timeout} = [$1]; |
655 |
} elsif (/^attempts:(\d+)$/) { |
656 |
$attempts = $1; |
657 |
} elsif (/^ndots:(\d+)$/) { |
658 |
$self->{ndots} = $1; |
659 |
} else { |
660 |
# debug, rotate, no-check-names, inet6 |
661 |
} |
662 |
} |
663 |
} |
664 |
} |
665 |
|
666 |
$self->{timeout} = [($self->{timeout}[0]) x $attempts] |
667 |
if $attempts; |
668 |
|
669 |
$self->_compile; |
670 |
} |
671 |
|
672 |
=item $resolver->os_config |
673 |
|
674 |
Tries so load and parse F</etc/resolv.conf> on portable opertaing systems. Tries various |
675 |
egregious hacks on windows to force the dns servers and searchlist out of the config. |
676 |
|
677 |
=cut |
678 |
|
679 |
sub os_config { |
680 |
my ($self) = @_; |
681 |
|
682 |
if ($^O =~ /mswin32|cygwin/i) { |
683 |
# yeah, it suxx... lets hope DNS is DNS in all locales |
684 |
|
685 |
if (open my $fh, "ipconfig /all |") { |
686 |
delete $self->{server}; |
687 |
delete $self->{search}; |
688 |
|
689 |
while (<$fh>) { |
690 |
# first DNS.* is suffix list |
691 |
if (/^\s*DNS/) { |
692 |
while (/\s+([[:alnum:].\-]+)\s*$/) { |
693 |
push @{ $self->{search} }, $1; |
694 |
$_ = <$fh>; |
695 |
} |
696 |
last; |
697 |
} |
698 |
} |
699 |
|
700 |
while (<$fh>) { |
701 |
# second DNS.* is server address list |
702 |
if (/^\s*DNS/) { |
703 |
while (/\s+(\d+\.\d+\.\d+\.\d+)\s*$/) { |
704 |
my $ip = $1; |
705 |
push @{ $self->{server} }, AnyEvent::Util::socket_inet_aton $ip |
706 |
if AnyEvent::Util::dotted_quad $ip; |
707 |
$_ = <$fh>; |
708 |
} |
709 |
last; |
710 |
} |
711 |
} |
712 |
|
713 |
$self->_compile; |
714 |
} |
715 |
} else { |
716 |
# try resolv.conf everywhere |
717 |
|
718 |
if (open my $fh, "</etc/resolv.conf") { |
719 |
local $/; |
720 |
$self->parse_resolv_conf (<$fh>); |
721 |
} |
722 |
} |
723 |
} |
724 |
|
725 |
sub _compile { |
726 |
my $self = shift; |
727 |
|
728 |
my @retry; |
729 |
|
730 |
for my $timeout (@{ $self->{timeout} }) { |
731 |
for my $server (@{ $self->{server} }) { |
732 |
push @retry, [$server, $timeout]; |
733 |
} |
734 |
} |
735 |
|
736 |
$self->{retry} = \@retry; |
737 |
} |
738 |
|
739 |
sub _feed { |
740 |
my ($self, $res) = @_; |
741 |
|
742 |
$res = dns_unpack $res |
743 |
or return; |
744 |
|
745 |
my $id = $self->{id}{$res->{id}}; |
746 |
|
747 |
return unless ref $id; |
748 |
|
749 |
$NOW = time; |
750 |
$id->[1]->($res); |
751 |
} |
752 |
|
753 |
sub _recv { |
754 |
my ($self) = @_; |
755 |
|
756 |
while (my $peer = recv $self->{fh}, my $res, 4096, 0) { |
757 |
my ($port, $host) = Socket::unpack_sockaddr_in $peer; |
758 |
|
759 |
return unless $port == 53 && grep $_ eq $host, @{ $self->{server} }; |
760 |
|
761 |
$self->_feed ($res); |
762 |
} |
763 |
} |
764 |
|
765 |
sub _exec { |
766 |
my ($self, $req, $retry) = @_; |
767 |
|
768 |
if (my $retry_cfg = $self->{retry}[$retry]) { |
769 |
my ($server, $timeout) = @$retry_cfg; |
770 |
|
771 |
$self->{id}{$req->[2]} = [AnyEvent->timer (after => $timeout, cb => sub { |
772 |
$NOW = time; |
773 |
|
774 |
# timeout, try next |
775 |
$self->_exec ($req, $retry + 1); |
776 |
}), sub { |
777 |
my ($res) = @_; |
778 |
|
779 |
if ($res->{tc}) { |
780 |
# success, but truncated, so use tcp |
781 |
AnyEvent::Util::tcp_connect +(Socket::inet_ntoa $server), 53, sub { |
782 |
my ($fh) = @_ |
783 |
or return $self->_exec ($req, $retry + 1); |
784 |
|
785 |
my $handle = new AnyEvent::Handle |
786 |
fh => $fh, |
787 |
on_error => sub { |
788 |
# failure, try next |
789 |
$self->_exec ($req, $retry + 1); |
790 |
}; |
791 |
|
792 |
$handle->push_write (pack "n/a", $req->[0]); |
793 |
$handle->push_read_chunk (2, sub { |
794 |
$handle->unshift_read_chunk ((unpack "n", $_[1]), sub { |
795 |
$self->_feed ($_[1]); |
796 |
}); |
797 |
}); |
798 |
shutdown $fh, 1; |
799 |
|
800 |
}, sub { $timeout }; |
801 |
|
802 |
} else { |
803 |
# success |
804 |
$self->{id}{$req->[2]} = 1; |
805 |
push @{ $self->{reuse_q} }, [$NOW + $self->{reuse}, $req->[2]]; |
806 |
--$self->{outstanding}; |
807 |
$self->_scheduler; |
808 |
|
809 |
$req->[1]->($res); |
810 |
} |
811 |
}]; |
812 |
|
813 |
send $self->{fh}, $req->[0], 0, Socket::pack_sockaddr_in 53, $server; |
814 |
} else { |
815 |
# failure |
816 |
$self->{id}{$req->[2]} = 1; |
817 |
push @{ $self->{reuse_q} }, [$NOW + $self->{reuse}, $req->[2]]; |
818 |
--$self->{outstanding}; |
819 |
$self->_scheduler; |
820 |
|
821 |
$req->[1]->(); |
822 |
} |
823 |
} |
824 |
|
825 |
sub _scheduler { |
826 |
my ($self) = @_; |
827 |
|
828 |
$NOW = time; |
829 |
|
830 |
# first clear id reuse queue |
831 |
delete $self->{id}{ (shift @{ $self->{reuse_q} })->[1] } |
832 |
while @{ $self->{reuse_q} } && $self->{reuse_q}[0][0] <= $NOW; |
833 |
|
834 |
while ($self->{outstanding} < $self->{max_outstanding}) { |
835 |
|
836 |
if (@{ $self->{reuse_q} } >= 30000) { |
837 |
# we ran out of ID's, wait a bit |
838 |
$self->{reuse_to} ||= AnyEvent->timer (after => $self->{reuse_q}[0][0] - $NOW, cb => sub { |
839 |
delete $self->{reuse_to}; |
840 |
$self->_scheduler; |
841 |
}); |
842 |
last; |
843 |
} |
844 |
|
845 |
my $req = shift @{ $self->{queue} } |
846 |
or last; |
847 |
|
848 |
while () { |
849 |
$req->[2] = int rand 65536; |
850 |
last unless exists $self->{id}{$req->[2]}; |
851 |
} |
852 |
|
853 |
$self->{id}{$req->[2]} = 1; |
854 |
substr $req->[0], 0, 2, pack "n", $req->[2]; |
855 |
|
856 |
++$self->{outstanding}; |
857 |
$self->_exec ($req, 0); |
858 |
} |
859 |
} |
860 |
|
861 |
=item $resolver->request ($req, $cb->($res)) |
862 |
|
863 |
Sends a single request (a hash-ref formated as specified for |
864 |
C<dns_pack>) to the configured nameservers including |
865 |
retries. Calls the callback with the decoded response packet if a reply |
866 |
was received, or no arguments on timeout. |
867 |
|
868 |
=cut |
869 |
|
870 |
sub request($$) { |
871 |
my ($self, $req, $cb) = @_; |
872 |
|
873 |
push @{ $self->{queue} }, [dns_pack $req, $cb]; |
874 |
$self->_scheduler; |
875 |
} |
876 |
|
877 |
=item $resolver->resolve ($qname, $qtype, %options, $cb->($rcode, @rr)) |
878 |
|
879 |
Queries the DNS for the given domain name C<$qname> of type C<$qtype> (a |
880 |
qtype of "*" is supported and means "any"). |
881 |
|
882 |
The callback will be invoked with a list of matching result records or |
883 |
none on any error or if the name could not be found. |
884 |
|
885 |
CNAME chains (although illegal) are followed up to a length of 8. |
886 |
|
887 |
Note that this resolver is just a stub resolver: it requires a nameserver |
888 |
supporting recursive queries, will not do any recursive queries itself and |
889 |
is not secure when used against an untrusted name server. |
890 |
|
891 |
The following options are supported: |
892 |
|
893 |
=over 4 |
894 |
|
895 |
=item search => [$suffix...] |
896 |
|
897 |
Use the given search list (which might be empty), by appending each one |
898 |
in turn to the C<$qname>. If this option is missing then the configured |
899 |
C<ndots> and C<search> define its value. If the C<$qname> ends in a dot, |
900 |
then the searchlist will be ignored. |
901 |
|
902 |
=item accept => [$type...] |
903 |
|
904 |
Lists the acceptable result types: only result types in this set will be |
905 |
accepted and returned. The default includes the C<$qtype> and nothing |
906 |
else. |
907 |
|
908 |
=item class => "class" |
909 |
|
910 |
Specify the query class ("in" for internet, "ch" for chaosnet and "hs" for |
911 |
hesiod are the only ones making sense). The default is "in", of course. |
912 |
|
913 |
=back |
914 |
|
915 |
Examples: |
916 |
|
917 |
$res->resolve ("ruth.plan9.de", "a", sub { |
918 |
warn Dumper [@_]; |
919 |
}); |
920 |
|
921 |
[ |
922 |
[ |
923 |
'ruth.schmorp.de', |
924 |
'a', |
925 |
'in', |
926 |
'129.13.162.95' |
927 |
] |
928 |
] |
929 |
|
930 |
$res->resolve ("test1.laendle", "*", |
931 |
accept => ["a", "aaaa"], |
932 |
sub { |
933 |
warn Dumper [@_]; |
934 |
} |
935 |
); |
936 |
|
937 |
[ |
938 |
[ |
939 |
'test1.laendle', |
940 |
'a', |
941 |
'in', |
942 |
'10.0.0.255' |
943 |
], |
944 |
[ |
945 |
'test1.laendle', |
946 |
'aaaa', |
947 |
'in', |
948 |
'3ffe:1900:4545:0002:0240:0000:0000:f7e1' |
949 |
] |
950 |
] |
951 |
|
952 |
=cut |
953 |
|
954 |
sub resolve($%) { |
955 |
my $cb = pop; |
956 |
my ($self, $qname, $qtype, %opt) = @_; |
957 |
|
958 |
my @search = $qname =~ s/\.$// |
959 |
? "" |
960 |
: $opt{search} |
961 |
? @{ $opt{search} } |
962 |
: ($qname =~ y/.//) >= $self->{ndots} |
963 |
? ("", @{ $self->{search} }) |
964 |
: (@{ $self->{search} }, ""); |
965 |
|
966 |
my $class = $opt{class} || "in"; |
967 |
|
968 |
my %atype = $opt{accept} |
969 |
? map +($_ => 1), @{ $opt{accept} } |
970 |
: ($qtype => 1); |
971 |
|
972 |
# advance in searchlist |
973 |
my $do_search; $do_search = sub { |
974 |
@search |
975 |
or return $cb->(); |
976 |
|
977 |
(my $name = lc "$qname." . shift @search) =~ s/\.$//; |
978 |
my $depth = 2; |
979 |
|
980 |
# advance in cname-chain |
981 |
my $do_req; $do_req = sub { |
982 |
$self->request ({ |
983 |
rd => 1, |
984 |
qd => [[$name, $qtype, $class]], |
985 |
}, sub { |
986 |
my ($res) = @_ |
987 |
or return $do_search->(); |
988 |
|
989 |
my $cname; |
990 |
|
991 |
while () { |
992 |
# results found? |
993 |
my @rr = grep $name eq lc $_->[0] && ($atype{"*"} || $atype{$_->[1]}), @{ $res->{an} }; |
994 |
|
995 |
return $cb->(@rr) |
996 |
if @rr; |
997 |
|
998 |
# see if there is a cname we can follow |
999 |
my @rr = grep $name eq lc $_->[0] && $_->[1] eq "cname", @{ $res->{an} }; |
1000 |
|
1001 |
if (@rr) { |
1002 |
$depth-- |
1003 |
or return $do_search->(); # cname chain too long |
1004 |
|
1005 |
$cname = 1; |
1006 |
$name = $rr[0][3]; |
1007 |
|
1008 |
} elsif ($cname) { |
1009 |
# follow the cname |
1010 |
return $do_req->(); |
1011 |
|
1012 |
} else { |
1013 |
# no, not found anything |
1014 |
return $do_search->(); |
1015 |
} |
1016 |
} |
1017 |
}); |
1018 |
}; |
1019 |
|
1020 |
$do_req->(); |
1021 |
}; |
1022 |
|
1023 |
$do_search->(); |
1024 |
} |
1025 |
|
1026 |
1; |
1027 |
|
1028 |
=back |
1029 |
|
1030 |
=head1 AUTHOR |
1031 |
|
1032 |
Marc Lehmann <schmorp@schmorp.de> |
1033 |
http://home.schmorp.de/ |
1034 |
|
1035 |
=cut |
1036 |
|