Support all resolvers in resolv.conf, and issue retries on errors the same
way gethostbyname() does. git-svn-id: https://svn.perl.org/qpsmtpd/trunk@555 958fd67b-6ff1-0310-b445-bb7760255be9
This commit is contained in:
Matt Sergeant
parent
22fef51c19
commit
0a397e74a9
@ -3,7 +3,7 @@
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package Danga::DNS::Resolver;
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use base qw(Danga::Socket);
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use fields qw(res dst id_to_asker id_to_query timeout cache cache_timeout);
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use fields qw(res dst cache cache_timeout queries);
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use Net::DNS;
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use Socket;
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@ -30,16 +30,16 @@ sub new {
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) || die "Cannot create socket: $!";
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IO::Handle::blocking($sock, 0);
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trace(2, "Using nameserver $res->{nameservers}->[0]:$res->{port}\n");
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my $dst_sockaddr = sockaddr_in($res->{'port'}, inet_aton($res->{'nameservers'}->[0]));
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#my $dst_sockaddr = sockaddr_in($res->{'port'}, inet_aton('127.0.0.1'));
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#my $dst_sockaddr = sockaddr_in($res->{'port'}, inet_aton('10.2.1.20'));
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$self->{dst} = [];
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foreach my $ns (@{ $res->{nameservers} }) {
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trace(2, "Using nameserver $ns:$res->{port}\n");
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my $dst_sockaddr = sockaddr_in($res->{'port'}, inet_aton($ns));
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push @{$self->{dst}}, $dst_sockaddr;
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}
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$self->{res} = $res;
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$self->{dst} = $dst_sockaddr;
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$self->{id_to_asker} = {};
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$self->{id_to_query} = {};
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$self->{timeout} = {};
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$self->{queries} = {};
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$self->{cache} = {};
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$self->{cache_timeout} = {};
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@ -52,10 +52,17 @@ sub new {
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return $self;
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}
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sub ns {
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my Danga::DNS::Resolver $self = shift;
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my $index = shift;
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return if $index > $#{$self->{dst}};
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return $self->{dst}->[$index];
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}
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sub pending {
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my Danga::DNS::Resolver $self = shift;
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return keys(%{$self->{id_to_asker}});
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return keys(%{$self->{queries}});
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}
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sub _query {
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@ -73,20 +80,14 @@ sub _query {
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}
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my $packet = $self->{res}->make_query_packet($host, $type);
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my $packet_data = $packet->data;
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my $id = $packet->header->id;
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my $h = $packet->header;
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my $id = $h->id;
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if (!$self->sock->send($packet_data, 0, $self->{dst})) {
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return;
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}
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trace(2, "Query: $host ($id)\n");
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$self->{id_to_asker}->{$id} = $asker;
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$self->{id_to_query}->{$id} = $host;
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$self->{timeout}->{$id} = $now;
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my $query = Danga::DNS::Resolver::Query->new(
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$self, $asker, $host, $type, $now, $id, $packet_data,
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) or return;
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$self->{queries}->{$id} = $query;
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return 1;
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}
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@ -97,15 +98,12 @@ sub query_txt {
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my $now = time();
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trace(2, "[" . keys(%{$self->{id_to_asker}}) . "] trying to resolve TXT: @hosts\n");
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trace(2, "trying to resolve TXT: @hosts\n");
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foreach my $host (@hosts) {
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$self->_query($asker, $host, 'TXT', $now) || return;
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}
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#print "+Pending queries: " . keys(%{$self->{id_to_asker}}) .
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# " / Cache Size: " . keys(%{$self->{cache}}) . "\n";
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return 1;
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}
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@ -115,15 +113,12 @@ sub query_mx {
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my $now = time();
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trace(2, "[" . keys(%{$self->{id_to_asker}}) . "] trying to resolve MX: @hosts\n");
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trace(2, "trying to resolve MX: @hosts\n");
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foreach my $host (@hosts) {
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$self->_query($asker, $host, 'MX', $now) || return;
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}
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#print "+Pending queries: " . keys(%{$self->{id_to_asker}}) .
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# " / Cache Size: " . keys(%{$self->{cache}}) . "\n";
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return 1;
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}
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@ -133,15 +128,12 @@ sub query {
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my $now = time();
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trace(2, "[" . keys(%{$self->{id_to_asker}}) . "] trying to resolve A/PTR: @hosts\n");
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trace(2, "trying to resolve A/PTR: @hosts\n");
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foreach my $host (@hosts) {
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$self->_query($asker, $host, 'A', $now) || return;
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}
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#print "+Pending queries: " . keys(%{$self->{id_to_asker}}) .
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# " / Cache Size: " . keys(%{$self->{cache}}) . "\n";
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return 1;
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}
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@ -154,20 +146,20 @@ sub _do_cleanup {
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my $idle = $self->max_idle_time;
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my @to_delete;
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while (my ($id, $t) = each(%{$self->{timeout}})) {
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if ($t < ($now - $idle)) {
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while (my ($id, $obj) = each(%{$self->{queries}})) {
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if ($obj->{timeout} < ($now - $idle)) {
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push @to_delete, $id;
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}
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}
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foreach my $id (@to_delete) {
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delete $self->{timeout}{$id};
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my $asker = delete $self->{id_to_asker}{$id};
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my $query = delete $self->{id_to_query}{$id};
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$asker->run_callback("NXDOMAIN", $query);
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my $query = delete $self->{queries}{$id};
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$query->timeout() and next;
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# add back in if timeout caused us to loop to next server
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$self->{queries}->{$id} = $query;
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}
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foreach my $type ('A', 'TXT') {
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foreach my $type ('A', 'TXT', 'MX') {
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@to_delete = ();
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while (my ($query, $t) = each(%{$self->{cache_timeout}{$type}})) {
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@ -199,17 +191,14 @@ sub event_read {
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my $header = $packet->header;
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my $id = $header->id;
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my $asker = delete $self->{id_to_asker}->{$id};
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my $query = delete $self->{id_to_query}->{$id};
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delete $self->{timeout}{$id};
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#print "-Pending queries: " . keys(%{$self->{id_to_asker}}) .
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# " / Cache Size: " . keys(%{$self->{cache}}) . "\n";
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if (!$asker) {
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trace(1, "No asker for id: $id\n");
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my $qobj = delete $self->{queries}->{$id};
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if (!$qobj) {
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trace(1, "No query for id: $id\n");
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return;
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}
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my $query = $qobj->{host};
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my $now = time();
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my @questions = $packet->question;
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#print STDERR "response to ", $questions[0]->string, "\n";
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@ -217,61 +206,64 @@ sub event_read {
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# my $q = shift @questions;
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if ($rr->type eq "PTR") {
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my $rdns = $rr->ptrdname;
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if ($query) {
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# NB: Cached as an "A" lookup as there's no overlap and they
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# go through the same query() function above
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$self->{cache}{A}{$query} = $rdns;
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$self->{cache_timeout}{A}{$query} = $now + 60; # should use $rr->ttl but that would cache for too long
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}
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$asker->run_callback($rdns, $query);
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# NB: Cached as an "A" lookup as there's no overlap and they
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# go through the same query() function above
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$self->{cache}{A}{$query} = $rdns;
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# $self->{cache_timeout}{A}{$query} = $now + 60; # should use $rr->ttl but that would cache for too long
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$self->{cache_timeout}{A}{$query} = $now + $rr->ttl;
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$qobj->run_callback($rdns);
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}
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elsif ($rr->type eq "A") {
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my $ip = $rr->address;
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if ($query) {
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$self->{cache}{A}{$query} = $ip;
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$self->{cache_timeout}{A}{$query} = $now + 60; # should use $rr->ttl but that would cache for too long
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}
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$asker->run_callback($ip, $query);
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$self->{cache}{A}{$query} = $ip;
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# $self->{cache_timeout}{A}{$query} = $now + 60; # should use $rr->ttl but that would cache for too long
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$self->{cache_timeout}{A}{$query} = $now + $rr->ttl;
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$qobj->run_callback($ip);
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}
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elsif ($rr->type eq "TXT") {
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my $txt = $rr->txtdata;
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if ($query) {
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$self->{cache}{TXT}{$query} = $txt;
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$self->{cache_timeout}{TXT}{$query} = $now + 60; # should use $rr->ttl but that would cache for too long
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}
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$asker->run_callback($txt, $query);
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$self->{cache}{TXT}{$query} = $txt;
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# $self->{cache_timeout}{TXT}{$query} = $now + 60; # should use $rr->ttl but that would cache for too long
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$self->{cache_timeout}{TXT}{$query} = $now + $rr->ttl;
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$qobj->run_callback($txt);
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}
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elsif ($rr->type eq "MX") {
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my $host = $rr->exchange;
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my $preference = $rr->preference;
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$self->{cache}{MX}{$query} = [$host, $preference];
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$self->{cache_timeout}{MX}{$query} = $now + $rr->ttl;
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$qobj->run_callback([$host, $preference]);
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}
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else {
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# came back, but not a PTR or A record
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$asker->run_callback("unknown", $query);
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$qobj->run_callback("UNKNOWN");
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}
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$answers++;
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}
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if (!$answers) {
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if ($err eq "NXDOMAIN") {
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# trace("found => NXDOMAIN\n");
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$asker->run_callback("NXDOMAIN", $query);
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$qobj->run_callback("NXDOMAIN");
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}
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elsif ($err eq "SERVFAIL") {
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# try again???
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print "SERVFAIL looking for $query (Pending: " . keys(%{$self->{id_to_asker}}) . ")\n";
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print "SERVFAIL looking for $query\n";
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#$self->query($asker, $query);
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$asker->run_callback($err, $query);
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#$self->{id_to_asker}->{$id} = $asker;
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#$self->{id_to_query}->{$id} = $query;
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#$self->{timeout}{$id} = time();
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$qobj->error($err) and next;
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# add back in if error() resulted in query being re-issued
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$self->{queries}->{$id} = $qobj;
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}
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elsif ($err eq "NOERROR") {
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$asker->run_callback($err, $query);
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$qobj->run_callback($err);
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}
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elsif($err) {
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print("error: $err\n");
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$asker->run_callback($err, $query);
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$qobj->error($err) and next;
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$self->{queries}->{$id} = $qobj;
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}
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else {
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# trace("no answers\n");
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$asker->run_callback("NXDOMAIN", $query);
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$qobj->run_callback("NOANSWER");
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}
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}
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}
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@ -286,6 +278,116 @@ sub close {
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# confess "Danga::DNS::Resolver socket should never be closed!";
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}
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package Danga::DNS::Resolver::Query;
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use constant MAX_QUERIES => 10;
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sub trace {
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my $level = shift;
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print ("$::DEBUG/$level [$$] dns lookup: @_") if $::DEBUG >= $level;
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}
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sub new {
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my ($class, $res, $asker, $host, $type, $now, $id, $data) = @_;
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my $self = {
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resolver => $res,
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asker => $asker,
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host => $host,
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type => $type,
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timeout => $now,
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id => $id,
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data => $data,
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repeat => 2, # number of retries
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ns => 0,
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nqueries => 0,
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};
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trace(2, "NS Query: $host ($id)\n");
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bless $self, $class;
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$self->send_query || return;
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return $self;
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}
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#sub DESTROY {
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# my $self = shift;
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# trace(2, "DESTROY $self\n");
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#}
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sub timeout {
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my $self = shift;
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trace(2, "NS Query timeout. Trying next host\n");
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if ($self->send_query) {
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# had another NS to send to, reset timeout
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$self->{timeout} = time();
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return;
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}
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# can we loop/repeat?
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if (($self->{nqueries} <= MAX_QUERIES) &&
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($self->{repeat} > 1))
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{
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trace(2, "NS Query timeout. Next host failed. Trying loop\n");
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$self->{repeat}--;
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$self->{ns} = 0;
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return $self->timeout();
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}
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trace(2, "NS Query timeout. All failed. Running callback(TIMEOUT)\n");
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# otherwise we really must timeout.
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$self->run_callback("TIMEOUT");
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return 1;
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}
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sub error {
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my ($self, $error) = @_;
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trace(2, "NS Query error. Trying next host\n");
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if ($self->send_query) {
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# had another NS to send to, reset timeout
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$self->{timeout} = time();
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return;
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}
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# can we loop/repeat?
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if (($self->{nqueries} <= MAX_QUERIES) &&
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($self->{repeat} > 1))
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{
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trace(2, "NS Query error. Next host failed. Trying loop\n");
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$self->{repeat}--;
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$self->{ns} = 0;
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return $self->error($error);
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}
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trace(2, "NS Query error. All failed. Running callback($error)\n");
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# otherwise we really must timeout.
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$self->run_callback($error);
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return 1;
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}
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sub run_callback {
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my ($self, $response) = @_;
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trace(2, "NS Query callback($self->{host} = $response\n");
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$self->{asker}->run_callback($response, $self->{host});
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}
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sub send_query {
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my ($self) = @_;
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my $dst = $self->{resolver}->ns($self->{ns}++);
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return unless defined $dst;
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if (!$self->{resolver}->sock->send($self->{data}, 0, $dst)) {
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return;
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}
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$self->{nqueries}++;
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return 1;
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}
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1;
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=head1 NAME
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Block a user