From 0a397e74a9c8470bb4b96c50881234fdf3b82ca5 Mon Sep 17 00:00:00 2001 From: Matt Sergeant Date: Wed, 26 Oct 2005 19:09:04 +0000 Subject: [PATCH] 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 --- lib/Danga/DNS/Resolver.pm | 256 ++++++++++++++++++++++++++------------ 1 file changed, 179 insertions(+), 77 deletions(-) diff --git a/lib/Danga/DNS/Resolver.pm b/lib/Danga/DNS/Resolver.pm index 48526a7..34c9e15 100644 --- a/lib/Danga/DNS/Resolver.pm +++ b/lib/Danga/DNS/Resolver.pm @@ -3,7 +3,7 @@ package Danga::DNS::Resolver; use base qw(Danga::Socket); -use fields qw(res dst id_to_asker id_to_query timeout cache cache_timeout); +use fields qw(res dst cache cache_timeout queries); use Net::DNS; use Socket; @@ -30,16 +30,16 @@ sub new { ) || die "Cannot create socket: $!"; IO::Handle::blocking($sock, 0); - trace(2, "Using nameserver $res->{nameservers}->[0]:$res->{port}\n"); - my $dst_sockaddr = sockaddr_in($res->{'port'}, inet_aton($res->{'nameservers'}->[0])); - #my $dst_sockaddr = sockaddr_in($res->{'port'}, inet_aton('127.0.0.1')); - #my $dst_sockaddr = sockaddr_in($res->{'port'}, inet_aton('10.2.1.20')); + $self->{dst} = []; + + foreach my $ns (@{ $res->{nameservers} }) { + trace(2, "Using nameserver $ns:$res->{port}\n"); + my $dst_sockaddr = sockaddr_in($res->{'port'}, inet_aton($ns)); + push @{$self->{dst}}, $dst_sockaddr; + } $self->{res} = $res; - $self->{dst} = $dst_sockaddr; - $self->{id_to_asker} = {}; - $self->{id_to_query} = {}; - $self->{timeout} = {}; + $self->{queries} = {}; $self->{cache} = {}; $self->{cache_timeout} = {}; @@ -52,10 +52,17 @@ sub new { return $self; } +sub ns { + my Danga::DNS::Resolver $self = shift; + my $index = shift; + return if $index > $#{$self->{dst}}; + return $self->{dst}->[$index]; +} + sub pending { my Danga::DNS::Resolver $self = shift; - return keys(%{$self->{id_to_asker}}); + return keys(%{$self->{queries}}); } sub _query { @@ -73,20 +80,14 @@ sub _query { } my $packet = $self->{res}->make_query_packet($host, $type); + my $packet_data = $packet->data; + my $id = $packet->header->id; - my $h = $packet->header; - my $id = $h->id; - - if (!$self->sock->send($packet_data, 0, $self->{dst})) { - return; - } - - trace(2, "Query: $host ($id)\n"); - - $self->{id_to_asker}->{$id} = $asker; - $self->{id_to_query}->{$id} = $host; - $self->{timeout}->{$id} = $now; + my $query = Danga::DNS::Resolver::Query->new( + $self, $asker, $host, $type, $now, $id, $packet_data, + ) or return; + $self->{queries}->{$id} = $query; return 1; } @@ -97,15 +98,12 @@ sub query_txt { my $now = time(); - trace(2, "[" . keys(%{$self->{id_to_asker}}) . "] trying to resolve TXT: @hosts\n"); + trace(2, "trying to resolve TXT: @hosts\n"); foreach my $host (@hosts) { $self->_query($asker, $host, 'TXT', $now) || return; } - #print "+Pending queries: " . keys(%{$self->{id_to_asker}}) . - # " / Cache Size: " . keys(%{$self->{cache}}) . "\n"; - return 1; } @@ -115,15 +113,12 @@ sub query_mx { my $now = time(); - trace(2, "[" . keys(%{$self->{id_to_asker}}) . "] trying to resolve MX: @hosts\n"); + trace(2, "trying to resolve MX: @hosts\n"); foreach my $host (@hosts) { $self->_query($asker, $host, 'MX', $now) || return; } - #print "+Pending queries: " . keys(%{$self->{id_to_asker}}) . - # " / Cache Size: " . keys(%{$self->{cache}}) . "\n"; - return 1; } @@ -133,15 +128,12 @@ sub query { my $now = time(); - trace(2, "[" . keys(%{$self->{id_to_asker}}) . "] trying to resolve A/PTR: @hosts\n"); + trace(2, "trying to resolve A/PTR: @hosts\n"); foreach my $host (@hosts) { $self->_query($asker, $host, 'A', $now) || return; } - #print "+Pending queries: " . keys(%{$self->{id_to_asker}}) . - # " / Cache Size: " . keys(%{$self->{cache}}) . "\n"; - return 1; } @@ -154,20 +146,20 @@ sub _do_cleanup { my $idle = $self->max_idle_time; my @to_delete; - while (my ($id, $t) = each(%{$self->{timeout}})) { - if ($t < ($now - $idle)) { + while (my ($id, $obj) = each(%{$self->{queries}})) { + if ($obj->{timeout} < ($now - $idle)) { push @to_delete, $id; } } foreach my $id (@to_delete) { - delete $self->{timeout}{$id}; - my $asker = delete $self->{id_to_asker}{$id}; - my $query = delete $self->{id_to_query}{$id}; - $asker->run_callback("NXDOMAIN", $query); + my $query = delete $self->{queries}{$id}; + $query->timeout() and next; + # add back in if timeout caused us to loop to next server + $self->{queries}->{$id} = $query; } - foreach my $type ('A', 'TXT') { + foreach my $type ('A', 'TXT', 'MX') { @to_delete = (); while (my ($query, $t) = each(%{$self->{cache_timeout}{$type}})) { @@ -199,17 +191,14 @@ sub event_read { my $header = $packet->header; my $id = $header->id; - my $asker = delete $self->{id_to_asker}->{$id}; - my $query = delete $self->{id_to_query}->{$id}; - delete $self->{timeout}{$id}; - - #print "-Pending queries: " . keys(%{$self->{id_to_asker}}) . - # " / Cache Size: " . keys(%{$self->{cache}}) . "\n"; - if (!$asker) { - trace(1, "No asker for id: $id\n"); + my $qobj = delete $self->{queries}->{$id}; + if (!$qobj) { + trace(1, "No query for id: $id\n"); return; } + my $query = $qobj->{host}; + my $now = time(); my @questions = $packet->question; #print STDERR "response to ", $questions[0]->string, "\n"; @@ -217,61 +206,64 @@ sub event_read { # my $q = shift @questions; if ($rr->type eq "PTR") { my $rdns = $rr->ptrdname; - if ($query) { - # NB: Cached as an "A" lookup as there's no overlap and they - # go through the same query() function above - $self->{cache}{A}{$query} = $rdns; - $self->{cache_timeout}{A}{$query} = $now + 60; # should use $rr->ttl but that would cache for too long - } - $asker->run_callback($rdns, $query); + # NB: Cached as an "A" lookup as there's no overlap and they + # go through the same query() function above + $self->{cache}{A}{$query} = $rdns; + # $self->{cache_timeout}{A}{$query} = $now + 60; # should use $rr->ttl but that would cache for too long + $self->{cache_timeout}{A}{$query} = $now + $rr->ttl; + $qobj->run_callback($rdns); } elsif ($rr->type eq "A") { my $ip = $rr->address; - if ($query) { - $self->{cache}{A}{$query} = $ip; - $self->{cache_timeout}{A}{$query} = $now + 60; # should use $rr->ttl but that would cache for too long - } - $asker->run_callback($ip, $query); + $self->{cache}{A}{$query} = $ip; + # $self->{cache_timeout}{A}{$query} = $now + 60; # should use $rr->ttl but that would cache for too long + $self->{cache_timeout}{A}{$query} = $now + $rr->ttl; + $qobj->run_callback($ip); } elsif ($rr->type eq "TXT") { my $txt = $rr->txtdata; - if ($query) { - $self->{cache}{TXT}{$query} = $txt; - $self->{cache_timeout}{TXT}{$query} = $now + 60; # should use $rr->ttl but that would cache for too long - } - $asker->run_callback($txt, $query); + $self->{cache}{TXT}{$query} = $txt; + # $self->{cache_timeout}{TXT}{$query} = $now + 60; # should use $rr->ttl but that would cache for too long + $self->{cache_timeout}{TXT}{$query} = $now + $rr->ttl; + $qobj->run_callback($txt); + } + elsif ($rr->type eq "MX") { + my $host = $rr->exchange; + my $preference = $rr->preference; + $self->{cache}{MX}{$query} = [$host, $preference]; + $self->{cache_timeout}{MX}{$query} = $now + $rr->ttl; + $qobj->run_callback([$host, $preference]); } else { # came back, but not a PTR or A record - $asker->run_callback("unknown", $query); + $qobj->run_callback("UNKNOWN"); } $answers++; } if (!$answers) { if ($err eq "NXDOMAIN") { # trace("found => NXDOMAIN\n"); - $asker->run_callback("NXDOMAIN", $query); + $qobj->run_callback("NXDOMAIN"); } elsif ($err eq "SERVFAIL") { # try again??? - print "SERVFAIL looking for $query (Pending: " . keys(%{$self->{id_to_asker}}) . ")\n"; + print "SERVFAIL looking for $query\n"; #$self->query($asker, $query); - $asker->run_callback($err, $query); - #$self->{id_to_asker}->{$id} = $asker; - #$self->{id_to_query}->{$id} = $query; - #$self->{timeout}{$id} = time(); - + $qobj->error($err) and next; + # add back in if error() resulted in query being re-issued + $self->{queries}->{$id} = $qobj; } elsif ($err eq "NOERROR") { - $asker->run_callback($err, $query); + $qobj->run_callback($err); } elsif($err) { print("error: $err\n"); - $asker->run_callback($err, $query); + $qobj->error($err) and next; + $self->{queries}->{$id} = $qobj; } else { # trace("no answers\n"); - $asker->run_callback("NXDOMAIN", $query); + $qobj->run_callback("NOANSWER"); } } } @@ -286,6 +278,116 @@ sub close { # confess "Danga::DNS::Resolver socket should never be closed!"; } +package Danga::DNS::Resolver::Query; + +use constant MAX_QUERIES => 10; + +sub trace { + my $level = shift; + print ("$::DEBUG/$level [$$] dns lookup: @_") if $::DEBUG >= $level; +} + +sub new { + my ($class, $res, $asker, $host, $type, $now, $id, $data) = @_; + + my $self = { + resolver => $res, + asker => $asker, + host => $host, + type => $type, + timeout => $now, + id => $id, + data => $data, + repeat => 2, # number of retries + ns => 0, + nqueries => 0, + }; + + trace(2, "NS Query: $host ($id)\n"); + + bless $self, $class; + + $self->send_query || return; + + return $self; +} + +#sub DESTROY { +# my $self = shift; +# trace(2, "DESTROY $self\n"); +#} + +sub timeout { + my $self = shift; + + trace(2, "NS Query timeout. Trying next host\n"); + if ($self->send_query) { + # had another NS to send to, reset timeout + $self->{timeout} = time(); + return; + } + + # can we loop/repeat? + if (($self->{nqueries} <= MAX_QUERIES) && + ($self->{repeat} > 1)) + { + trace(2, "NS Query timeout. Next host failed. Trying loop\n"); + $self->{repeat}--; + $self->{ns} = 0; + return $self->timeout(); + } + + trace(2, "NS Query timeout. All failed. Running callback(TIMEOUT)\n"); + # otherwise we really must timeout. + $self->run_callback("TIMEOUT"); + return 1; +} + +sub error { + my ($self, $error) = @_; + + trace(2, "NS Query error. Trying next host\n"); + if ($self->send_query) { + # had another NS to send to, reset timeout + $self->{timeout} = time(); + return; + } + + # can we loop/repeat? + if (($self->{nqueries} <= MAX_QUERIES) && + ($self->{repeat} > 1)) + { + trace(2, "NS Query error. Next host failed. Trying loop\n"); + $self->{repeat}--; + $self->{ns} = 0; + return $self->error($error); + } + + trace(2, "NS Query error. All failed. Running callback($error)\n"); + # otherwise we really must timeout. + $self->run_callback($error); + return 1; +} + +sub run_callback { + my ($self, $response) = @_; + trace(2, "NS Query callback($self->{host} = $response\n"); + $self->{asker}->run_callback($response, $self->{host}); +} + +sub send_query { + my ($self) = @_; + + my $dst = $self->{resolver}->ns($self->{ns}++); + return unless defined $dst; + if (!$self->{resolver}->sock->send($self->{data}, 0, $dst)) { + return; + } + + $self->{nqueries}++; + return 1; +} + 1; =head1 NAME