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root |
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=head1 NAME |
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AnyEvent::DNS - fully asynchronous DNS resolution |
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=head1 SYNOPSIS |
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use AnyEvent::DNS; |
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=head1 DESCRIPTION |
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This module offers both a number of DNS convenience functions as well |
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as a fully asynchronous and high-performance pure-perl stub resolver. |
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=head2 CONVENIENCE FUNCTIONS |
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# none yet |
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=over 4 |
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=cut |
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package AnyEvent::DNS; |
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use strict; |
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use AnyEvent::Util (); |
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=back |
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=head2 DNS EN-/DECODING FUNCTIONS |
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=over 4 |
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=cut |
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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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map +($_ => $_), 3..15 |
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); |
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our %opcode_str = reverse %opcode_id; |
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our %rcode_id = ( |
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ok => 0, |
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formerr => 1, |
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servfail => 2, |
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nxdomain => 3, |
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notimp => 4, |
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refused => 5, |
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map +($_ => $_), 6..15 |
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); |
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our %rcode_str = reverse %rcode_id; |
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our %type_id = ( |
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a => 1, |
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ns => 2, |
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md => 3, |
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mf => 4, |
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cname => 5, |
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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, |
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hinfo => 13, |
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minfo => 14, |
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mx => 15, |
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txt => 16, |
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aaaa => 28, |
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srv => 33, |
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axfr => 252, |
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mailb => 253, |
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"*" => 255, |
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); |
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our %type_str = reverse %type_id; |
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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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"*" => 255, |
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); |
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our %class_str = reverse %class_id; |
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# names MUST have a trailing dot |
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sub _enc_qname($) { |
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pack "(C/a)*", (split /\./, shift), "" |
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} |
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sub _enc_qd() { |
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(_enc_qname $_->[0]) . pack "nn", |
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($_->[1] > 0 ? $_->[1] : $type_id {$_->[1]}), |
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($_->[2] > 0 ? $_->[2] : $class_id{$_->[2] || "in"}) |
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} |
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sub _enc_rr() { |
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die "encoding of resource records is not supported"; |
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} |
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=item $pkt = AnyEvent::DNS::dns_pack $dns |
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Packs a perl data structure into a DNS packet. Reading RFC1034 is strongly |
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recommended, then everything will be totally clear. Or maybe not. |
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Resource records are not yet encodable. |
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Examples: |
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# very simple request, using lots of default values: |
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{ rd => 1, qd => [ [ "host.domain", "a"] ] } |
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# more complex example, showing how flags etc. are named: |
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{ |
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id => 10000, |
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op => "query", |
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rc => "nxdomain", |
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# flags |
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qr => 1, |
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aa => 0, |
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tc => 0, |
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rd => 0, |
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ra => 0, |
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qd => [@rr], # query section |
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an => [@rr], # answer section |
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ns => [@rr], # authority section |
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ar => [@rr], # additional records section |
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} |
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=cut |
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sub dns_pack($) { |
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my ($req) = @_; |
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pack "nn nnnn a* a* a* a*", |
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$req->{id}, |
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! !$req->{qr} * 0x8000 |
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+ $opcode_id{$req->{op}} * 0x0800 |
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+ ! !$req->{aa} * 0x0400 |
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+ ! !$req->{tc} * 0x0200 |
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+ ! !$req->{rd} * 0x0100 |
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+ ! !$req->{ra} * 0x0080 |
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+ $rcode_id{$req->{rc}} * 0x0001, |
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scalar @{ $req->{qd} || [] }, |
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scalar @{ $req->{an} || [] }, |
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scalar @{ $req->{ns} || [] }, |
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scalar @{ $req->{ar} || [] }, |
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(join "", map _enc_qd, @{ $req->{qd} || [] }), |
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(join "", map _enc_rr, @{ $req->{an} || [] }), |
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(join "", map _enc_rr, @{ $req->{ns} || [] }), |
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(join "", map _enc_rr, @{ $req->{ar} || [] }); |
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} |
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our $ofs; |
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our $pkt; |
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# bitches |
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sub _dec_qname { |
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my @res; |
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my $redir; |
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my $ptr = $ofs; |
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my $cnt; |
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while () { |
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return undef if ++$cnt >= 256; # to avoid DoS attacks |
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my $len = ord substr $pkt, $ptr++, 1; |
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if ($len & 0xc0) { |
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$ptr++; |
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$ofs = $ptr if $ptr > $ofs; |
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$ptr = (unpack "n", substr $pkt, $ptr - 2, 2) & 0x3fff; |
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} elsif ($len) { |
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push @res, substr $pkt, $ptr, $len; |
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$ptr += $len; |
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} else { |
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$ofs = $ptr if $ptr > $ofs; |
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return join ".", @res; |
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} |
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} |
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} |
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sub _dec_qd { |
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my $qname = _dec_qname; |
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my ($qt, $qc) = unpack "nn", substr $pkt, $ofs; $ofs += 4; |
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[$qname, $type_str{$qt} || $qt, $class_str{$qc} || $qc] |
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} |
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our %dec_rr = ( |
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1 => sub { Socket::inet_ntoa $_ }, # a |
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2 => sub { local $ofs = $ofs - length; _dec_qname }, # ns |
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5 => sub { local $ofs = $ofs - length; _dec_qname }, # cname |
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6 => sub { |
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local $ofs = $ofs - length; |
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my $mname = _dec_qname; |
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my $rname = _dec_qname; |
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($mname, $rname, unpack "NNNNN", substr $pkt, $ofs) |
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}, # soa |
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11 => sub { ((Socket::inet_aton substr $_, 0, 4), unpack "C a*", substr $_, 4) }, # wks |
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12 => sub { local $ofs = $ofs - length; _dec_qname }, # ptr |
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13 => sub { unpack "C/a C/a", $_ }, |
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15 => sub { local $ofs = $ofs + 2 - length; ((unpack "n", $_), _dec_qname) }, # mx |
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16 => sub { unpack "C/a", $_ }, # txt |
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28 => sub { sprintf "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x", unpack "n8" }, # aaaa |
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33 => sub { local $ofs = $ofs + 6 - length; ((unpack "nnn", $_), _dec_qname) }, # srv |
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); |
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sub _dec_rr { |
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my $qname = _dec_qname; |
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my ($rt, $rc, $ttl, $rdlen) = unpack "nn N n", substr $pkt, $ofs; $ofs += 10; |
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local $_ = substr $pkt, $ofs, $rdlen; $ofs += $rdlen; |
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[ |
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$qname, |
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$type_str{$rt} || $rt, |
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$class_str{$rc} || $rc, |
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($dec_rr{$rt} || sub { $_ })->(), |
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] |
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} |
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=item $dns = AnyEvent::DNS::dns_unpack $pkt |
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Unpacks a DNS packet into a perl data structure. |
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Examples: |
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# a non-successful reply |
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{ |
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'qd' => [ |
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[ 'ruth.plan9.de.mach.uni-karlsruhe.de', '*', 'in' ] |
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], |
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'rc' => 'nxdomain', |
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'ar' => [], |
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'ns' => [ |
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[ |
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'uni-karlsruhe.de', |
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'soa', |
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'in', |
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'netserv.rz.uni-karlsruhe.de', |
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'hostmaster.rz.uni-karlsruhe.de', |
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2008052201, |
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10800, |
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1800, |
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2592000, |
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86400 |
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] |
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], |
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'tc' => '', |
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'ra' => 1, |
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'qr' => 1, |
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'id' => 45915, |
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'aa' => '', |
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'an' => [], |
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'rd' => 1, |
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'op' => 'query' |
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} |
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# a successful reply |
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{ |
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'qd' => [ [ 'www.google.de', 'a', 'in' ] ], |
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'rc' => 0, |
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'ar' => [ |
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[ 'a.l.google.com', 'a', 'in', '209.85.139.9' ], |
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[ 'b.l.google.com', 'a', 'in', '64.233.179.9' ], |
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[ 'c.l.google.com', 'a', 'in', '64.233.161.9' ], |
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], |
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'ns' => [ |
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[ 'l.google.com', 'ns', 'in', 'a.l.google.com' ], |
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[ 'l.google.com', 'ns', 'in', 'b.l.google.com' ], |
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], |
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'tc' => '', |
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'ra' => 1, |
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'qr' => 1, |
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'id' => 64265, |
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'aa' => '', |
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'an' => [ |
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[ 'www.google.de', 'cname', 'in', 'www.google.com' ], |
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[ 'www.google.com', 'cname', 'in', 'www.l.google.com' ], |
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[ 'www.l.google.com', 'a', 'in', '66.249.93.104' ], |
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[ 'www.l.google.com', 'a', 'in', '66.249.93.147' ], |
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], |
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'rd' => 1, |
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'op' => 0 |
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} |
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=cut |
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sub dns_unpack($) { |
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local $pkt = shift; |
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my ($id, $flags, $qd, $an, $ns, $ar) |
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= unpack "nn nnnn A*", $pkt; |
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local $ofs = 6 * 2; |
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{ |
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id => $id, |
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qr => ! ! ($flags & 0x8000), |
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aa => ! ! ($flags & 0x0400), |
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tc => ! ! ($flags & 0x0200), |
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rd => ! ! ($flags & 0x0100), |
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ra => ! ! ($flags & 0x0080), |
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op => $opcode_str{($flags & 0x001e) >> 11}, |
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rc => $rcode_str{($flags & 0x000f)}, |
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qd => [map _dec_qd, 1 .. $qd], |
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an => [map _dec_rr, 1 .. $an], |
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ns => [map _dec_rr, 1 .. $ns], |
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ar => [map _dec_rr, 1 .. $ar], |
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} |
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} |
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############################################################################# |
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=back |
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=head2 THE AnyEvent::DNS RESOLVER CLASS |
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This is the class which deos the actual protocol work. |
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=over 4 |
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=cut |
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use Carp (); |
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use Scalar::Util (); |
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use Socket (); |
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our $NOW; |
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=item $resolver = new AnyEvent::DNS key => value... |
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Creates and returns a new resolver. The following options are supported: |
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=over 4 |
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=item server => [...] |
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A list of server addressses (default C<v127.0.0.1>) in network format (4 |
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octets for IPv4, 16 octets for IPv6 - not yet supported). |
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=item timeout => [...] |
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A list of timeouts to use (also determines the number of retries). To make |
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three retries with individual time-outs of 2, 5 and 5 seconds, use C<[2, |
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5, 5]>, which is also the default. |
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=item search => [...] |
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The default search list of suffixes to append to a domain name (default: none). |
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=item ndots => $n |
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The number of dots (default: C<1>) that a name must have so that the resolver |
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tries to resolve the name without any suffixes first. |
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=item max_outstanding => $n |
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Most name servers do not handle many parallel requests very well. This option |
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limits the numbe rof outstanding requests to C<$n> (default: C<10>), that means |
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if you request more than this many requests, then the additional requests will be queued |
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until some other requests have been resolved. |
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=back |
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=cut |
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sub new { |
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my ($class, %arg) = @_; |
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socket my $fh, &Socket::AF_INET, &Socket::SOCK_DGRAM, 0 |
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or Carp::croak "socket: $!"; |
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AnyEvent::Util::fh_nonblocking $fh, 1; |
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my $self = bless { |
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server => [v127.0.0.1], |
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timeout => [2, 5, 5], |
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search => [], |
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ndots => 1, |
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max_outstanding => 10, |
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reuse => 300, # reuse id's after 5 minutes only, if possible |
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%arg, |
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fh => $fh, |
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reuse_q => [], |
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}, $class; |
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# search should default to gethostname's domain |
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# but perl lacks a good posix module |
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Scalar::Util::weaken (my $wself = $self); |
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$self->{rw} = AnyEvent->io (fh => $fh, poll => "r", cb => sub { $wself->_recv }); |
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|
407 |
|
|
$self->_compile; |
408 |
|
|
|
409 |
|
|
$self |
410 |
|
|
} |
411 |
|
|
|
412 |
|
|
=item $resolver->parse_resolv_conv ($string) |
413 |
|
|
|
414 |
|
|
Parses the given string a sif it were a F<resolv.conf> file. The following |
415 |
|
|
directives are supported: |
416 |
|
|
|
417 |
|
|
C<#>-style comments, C<nameserver>, C<domain>, C<search>, C<sortlist>, |
418 |
|
|
C<options> (C<timeout>, C<attempts>, C<ndots>). |
419 |
|
|
|
420 |
|
|
Everything else is silently ignored. |
421 |
|
|
|
422 |
|
|
=cut |
423 |
|
|
|
424 |
|
|
sub parse_resolv_conf { |
425 |
|
|
my ($self, $resolvconf) = @_; |
426 |
|
|
|
427 |
|
|
$self->{server} = []; |
428 |
|
|
$self->{search} = []; |
429 |
|
|
|
430 |
|
|
my $attempts; |
431 |
|
|
|
432 |
|
|
for (split /\n/, $resolvconf) { |
433 |
|
|
if (/^\s*#/) { |
434 |
|
|
# comment |
435 |
|
|
} elsif (/^\s*nameserver\s+(\S+)\s*$/i) { |
436 |
|
|
my $ip = $1; |
437 |
|
|
if (AnyEvent::Util::dotted_quad $ip) { |
438 |
|
|
push @{ $self->{server} }, AnyEvent::Util::socket_inet_aton $ip; |
439 |
|
|
} else { |
440 |
|
|
warn "nameserver $ip invalid and ignored\n"; |
441 |
|
|
} |
442 |
|
|
} elsif (/^\s*domain\s+(\S*)\s+$/i) { |
443 |
|
|
$self->{search} = [$1]; |
444 |
|
|
} elsif (/^\s*search\s+(.*?)\s*$/i) { |
445 |
|
|
$self->{search} = [split /\s+/, $1]; |
446 |
|
|
} elsif (/^\s*sortlist\s+(.*?)\s*$/i) { |
447 |
|
|
# ignored, NYI |
448 |
|
|
} elsif (/^\s*options\s+(.*?)\s*$/i) { |
449 |
|
|
for (split /\s+/, $1) { |
450 |
|
|
if (/^timeout:(\d+)$/) { |
451 |
|
|
$self->{timeout} = [$1]; |
452 |
|
|
} elsif (/^attempts:(\d+)$/) { |
453 |
|
|
$attempts = $1; |
454 |
|
|
} elsif (/^ndots:(\d+)$/) { |
455 |
|
|
$self->{ndots} = $1; |
456 |
|
|
} else { |
457 |
|
|
# debug, rotate, no-check-names, inet6 |
458 |
|
|
} |
459 |
|
|
} |
460 |
|
|
} |
461 |
|
|
} |
462 |
|
|
|
463 |
|
|
$self->{timeout} = [($self->{timeout}[0]) x $attempts] |
464 |
|
|
if $attempts; |
465 |
|
|
|
466 |
|
|
$self->_compile; |
467 |
|
|
} |
468 |
|
|
|
469 |
|
|
=item $resolver->load_resolv_conf |
470 |
|
|
|
471 |
|
|
Tries to load and parse F</etc/resolv.conf>. If there will ever be windows |
472 |
|
|
support, then this function will do the right thing under windows, too. |
473 |
|
|
|
474 |
|
|
=cut |
475 |
|
|
|
476 |
|
|
sub load_resolv_conf { |
477 |
|
|
my ($self) = @_; |
478 |
|
|
|
479 |
|
|
open my $fh, "</etc/resolv.conf" |
480 |
|
|
or return; |
481 |
|
|
|
482 |
|
|
local $/; |
483 |
|
|
$self->parse_resolv_conf (<$fh>); |
484 |
|
|
} |
485 |
|
|
|
486 |
|
|
sub _compile { |
487 |
|
|
my $self = shift; |
488 |
|
|
|
489 |
|
|
my @retry; |
490 |
|
|
|
491 |
|
|
for my $timeout (@{ $self->{timeout} }) { |
492 |
|
|
for my $server (@{ $self->{server} }) { |
493 |
|
|
push @retry, [$server, $timeout]; |
494 |
|
|
} |
495 |
|
|
} |
496 |
|
|
|
497 |
|
|
$self->{retry} = \@retry; |
498 |
|
|
} |
499 |
|
|
|
500 |
|
|
sub _recv { |
501 |
|
|
my ($self) = @_; |
502 |
|
|
|
503 |
|
|
while (my $peer = recv $self->{fh}, my $res, 1024, 0) { |
504 |
|
|
my ($port, $host) = Socket::unpack_sockaddr_in $peer; |
505 |
|
|
|
506 |
|
|
return unless $port == 53 && grep $_ eq $host, @{ $self->{server} }; |
507 |
|
|
|
508 |
|
|
$res = AnyEvent::DNS::dns_unpack $res |
509 |
|
|
or return; |
510 |
|
|
|
511 |
|
|
my $id = $self->{id}{$res->{id}}; |
512 |
|
|
|
513 |
|
|
return unless ref $id; |
514 |
|
|
|
515 |
|
|
$NOW = time; |
516 |
|
|
$id->[1]->($res); |
517 |
|
|
} |
518 |
|
|
} |
519 |
|
|
|
520 |
|
|
sub _exec { |
521 |
|
|
my ($self, $req, $retry) = @_; |
522 |
|
|
|
523 |
|
|
if (my $retry_cfg = $self->{retry}[$retry]) { |
524 |
|
|
my ($server, $timeout) = @$retry_cfg; |
525 |
|
|
|
526 |
|
|
$self->{id}{$req->[2]} = [AnyEvent->timer (after => $timeout, cb => sub { |
527 |
|
|
$NOW = time; |
528 |
|
|
|
529 |
|
|
# timeout, try next |
530 |
|
|
$self->_exec ($req, $retry + 1); |
531 |
|
|
}), sub { |
532 |
|
|
my ($res) = @_; |
533 |
|
|
|
534 |
|
|
# success |
535 |
|
|
$self->{id}{$req->[2]} = 1; |
536 |
|
|
push @{ $self->{reuse_q} }, [$NOW + $self->{reuse}, $req->[2]]; |
537 |
|
|
--$self->{outstanding}; |
538 |
|
|
$self->_scheduler; |
539 |
|
|
|
540 |
|
|
$req->[1]->($res); |
541 |
|
|
}]; |
542 |
|
|
|
543 |
|
|
send $self->{fh}, $req->[0], 0, Socket::pack_sockaddr_in 53, $server; |
544 |
|
|
} else { |
545 |
|
|
# failure |
546 |
|
|
$self->{id}{$req->[2]} = 1; |
547 |
|
|
push @{ $self->{reuse_q} }, [$NOW + $self->{reuse}, $req->[2]]; |
548 |
|
|
--$self->{outstanding}; |
549 |
|
|
$self->_scheduler; |
550 |
|
|
|
551 |
|
|
$req->[1]->(); |
552 |
|
|
} |
553 |
|
|
} |
554 |
|
|
|
555 |
|
|
sub _scheduler { |
556 |
|
|
my ($self) = @_; |
557 |
|
|
|
558 |
|
|
$NOW = time; |
559 |
|
|
|
560 |
|
|
# first clear id reuse queue |
561 |
|
|
delete $self->{id}{ (shift @{ $self->{reuse_q} })->[1] } |
562 |
|
|
while @{ $self->{reuse_q} } && $self->{reuse_q}[0] <= $NOW; |
563 |
|
|
|
564 |
|
|
while ($self->{outstanding} < $self->{max_outstanding}) { |
565 |
|
|
my $req = shift @{ $self->{queue} } |
566 |
|
|
or last; |
567 |
|
|
|
568 |
|
|
while () { |
569 |
|
|
$req->[2] = int rand 65536; |
570 |
|
|
last unless exists $self->{id}{$req->[2]}; |
571 |
|
|
} |
572 |
|
|
|
573 |
|
|
$self->{id}{$req->[2]} = 1; |
574 |
|
|
substr $req->[0], 0, 2, pack "n", $req->[2]; |
575 |
|
|
|
576 |
|
|
++$self->{outstanding}; |
577 |
|
|
$self->_exec ($req, 0); |
578 |
|
|
} |
579 |
|
|
} |
580 |
|
|
|
581 |
|
|
=item $resolver->request ($req, $cb->($res)) |
582 |
|
|
|
583 |
|
|
Sends a single request (a hash-ref formated as specified for |
584 |
|
|
C<AnyEvent::DNS::dns_pack>) to the configured nameservers including |
585 |
|
|
retries. Calls the callback with the decoded response packet if a reply |
586 |
|
|
was received, or no arguments on timeout. |
587 |
|
|
|
588 |
|
|
=cut |
589 |
|
|
|
590 |
|
|
sub request($$) { |
591 |
|
|
my ($self, $req, $cb) = @_; |
592 |
|
|
|
593 |
|
|
push @{ $self->{queue} }, [(AnyEvent::DNS::dns_pack $req), $cb]; |
594 |
|
|
$self->_scheduler; |
595 |
|
|
} |
596 |
|
|
|
597 |
|
|
=item $resolver->resolve ($qname, $qtype, %options, $cb->($rcode, @rr)) |
598 |
|
|
|
599 |
|
|
Queries the DNS for the given domain name C<$qname> of type C<$qtype> (a |
600 |
|
|
qtype of "*" is supported and means "any"). |
601 |
|
|
|
602 |
|
|
The callback will be invoked with a list of matching result records or |
603 |
|
|
none on any error or if the name could not be found. |
604 |
|
|
|
605 |
|
|
CNAME chains (although illegal) are followed up to a length of 8. |
606 |
|
|
|
607 |
|
|
The following options are supported: |
608 |
|
|
|
609 |
|
|
=over 4 |
610 |
|
|
|
611 |
|
|
=item search => [$suffix...] |
612 |
|
|
|
613 |
|
|
Use the given search list (which might be empty), by appending each one |
614 |
|
|
in turn to the C<$qname>. If this option is missing then the configured |
615 |
|
|
C<ndots> and C<search> define its value. If the C<$qname> ends in a dot, |
616 |
|
|
then this option is ignored completely. |
617 |
|
|
|
618 |
|
|
=item accept => [$type...] |
619 |
|
|
|
620 |
|
|
Lists the acceptable result types: only result types in this set will be |
621 |
|
|
accepted and returned. The default includes the C<$qtype> and nothing |
622 |
|
|
else. |
623 |
|
|
|
624 |
|
|
=item class => "class" |
625 |
|
|
|
626 |
|
|
Specify the query class ("in" for internet, "ch" for chaosnet and "hs" for |
627 |
|
|
hesiod are the only ones making sense). |
628 |
|
|
|
629 |
|
|
=back |
630 |
|
|
|
631 |
|
|
Examples: |
632 |
|
|
|
633 |
|
|
$res->resolve ("ruth.plan9.de", "a", sub { |
634 |
|
|
warn Dumper [@_]; |
635 |
|
|
}); |
636 |
|
|
|
637 |
|
|
[ |
638 |
|
|
[ |
639 |
|
|
'ruth.schmorp.de', |
640 |
|
|
'a', |
641 |
|
|
'in', |
642 |
|
|
'129.13.162.95' |
643 |
|
|
] |
644 |
|
|
] |
645 |
|
|
|
646 |
|
|
$res->resolve ("test1.laendle", "*", |
647 |
|
|
accept => ["a", "aaaa"], |
648 |
|
|
sub { |
649 |
|
|
warn Dumper [@_]; |
650 |
|
|
} |
651 |
|
|
); |
652 |
|
|
|
653 |
|
|
[ |
654 |
|
|
[ |
655 |
|
|
'test1.laendle', |
656 |
|
|
'a', |
657 |
|
|
'in', |
658 |
|
|
'10.0.0.255' |
659 |
|
|
], |
660 |
|
|
[ |
661 |
|
|
'test1.laendle', |
662 |
|
|
'aaaa', |
663 |
|
|
'in', |
664 |
|
|
'3ffe:1900:4545:0002:0240:0000:0000:f7e1' |
665 |
|
|
] |
666 |
|
|
] |
667 |
|
|
|
668 |
|
|
=cut |
669 |
|
|
|
670 |
|
|
sub resolve($%) { |
671 |
|
|
my $cb = pop; |
672 |
|
|
my ($self, $qname, $qtype, %opt) = @_; |
673 |
|
|
|
674 |
|
|
my @search = $qname =~ s/\.$// |
675 |
|
|
? "" |
676 |
|
|
: $opt{search} |
677 |
|
|
? @{ $opt{search} } |
678 |
|
|
: ($qname =~ y/.//) >= $self->{ndots} |
679 |
|
|
? ("", @{ $self->{search} }) |
680 |
|
|
: (@{ $self->{search} }, ""); |
681 |
|
|
|
682 |
|
|
my $class = $opt{class} || "in"; |
683 |
|
|
|
684 |
|
|
my %atype = $opt{accept} |
685 |
|
|
? map +($_ => 1), @{ $opt{accept} } |
686 |
|
|
: ($qtype => 1); |
687 |
|
|
|
688 |
|
|
# advance in searchlist |
689 |
|
|
my $do_search; $do_search = sub { |
690 |
|
|
@search |
691 |
|
|
or return $cb->(); |
692 |
|
|
|
693 |
|
|
(my $name = "$qname." . shift @search) =~ s/\.$//; |
694 |
|
|
my $depth = 2; |
695 |
|
|
|
696 |
|
|
# advance in cname-chain |
697 |
|
|
my $do_req; $do_req = sub { |
698 |
|
|
$self->request ({ |
699 |
|
|
rd => 1, |
700 |
|
|
qd => [[$name, $qtype, $class]], |
701 |
|
|
}, sub { |
702 |
|
|
my ($res) = @_ |
703 |
|
|
or return $do_search->(); |
704 |
|
|
|
705 |
|
|
my $cname; |
706 |
|
|
|
707 |
|
|
while () { |
708 |
|
|
my @rr = grep $_->[0] eq $name && ($atype{"*"} || $atype{$_->[1]}), @{ $res->{an} }; |
709 |
|
|
|
710 |
|
|
return $cb->(@rr) |
711 |
|
|
if @rr; |
712 |
|
|
|
713 |
|
|
# see if there is a cname we can follow |
714 |
|
|
my @rr = grep $_->[0] eq $name && $_->[1] eq "cname", @{ $res->{an} }; |
715 |
|
|
|
716 |
|
|
if (@rr) { |
717 |
|
|
$depth-- |
718 |
|
|
or return $do_search->(); # cname chain too long |
719 |
|
|
|
720 |
|
|
$cname = 1; |
721 |
|
|
$name = $rr[0][3]; |
722 |
|
|
|
723 |
|
|
} elsif ($cname) { |
724 |
|
|
# follow the cname |
725 |
|
|
return $do_req->(); |
726 |
|
|
|
727 |
|
|
} else { |
728 |
|
|
return $do_search->(); |
729 |
|
|
} |
730 |
|
|
} |
731 |
|
|
}); |
732 |
|
|
}; |
733 |
|
|
|
734 |
|
|
$do_req->(); |
735 |
|
|
}; |
736 |
|
|
|
737 |
|
|
$do_search->(); |
738 |
|
|
} |
739 |
|
|
|
740 |
|
|
1; |
741 |
|
|
|
742 |
|
|
=back |
743 |
|
|
|
744 |
|
|
=head1 AUTHOR |
745 |
|
|
|
746 |
|
|
Marc Lehmann <schmorp@schmorp.de> |
747 |
|
|
http://home.schmorp.de/ |
748 |
|
|
|
749 |
|
|
=cut |
750 |
|
|
|