$proto ||= "tcp";
   $type  ||= $proto eq "udp" ? SOCK_DGRAM : SOCK_STREAM;

   my $proton = (getprotobyname $proto)[2]
      or Carp::croak "$proto: protocol unknown";

   my $port;

   if ($service =~ /^(\S+)=(\d+)$/) {
      ($service, $port) = ($1, $2);
   } elsif ($service =~ /^\d+$/) {
      ($service, $port) = (undef, $service);
   } else {
      $port = (getservbyname $service, $proto)[2]
              or Carp::croak "$service/$proto: service unknown";
   }

   my @target = [$node, $port];

   # resolve a records / provide sockaddr structures
   my $resolve = sub {
      my @res;
      my $cv = AnyEvent->condvar (cb => sub {
         $cb->(
            map $_->[2],
            sort {
               $AnyEvent::PROTOCOL{$b->[1]} <=> $AnyEvent::PROTOCOL{$a->[1]}
                  or $a->[0] <=> $b->[0]
            }
            @res
         )
      });

      $cv->begin;
      for my $idx (0 .. $#target) {
         my ($node, $port) = @{ $target[$idx] };

         if (my $noden = parse_address $node) {
            my $af = address_family $noden;

            if ($af == AF_INET && $family != 6) {
               push @res, [$idx, "ipv4", [AF_INET, $type, $proton,
                           pack_sockaddr $port, $noden]]
            }

            if ($af == AF_INET6 && $family != 4) {
               push @res, [$idx, "ipv6", [AF_INET6, $type, $proton,
                           pack_sockaddr $port, $noden]]
            }
         } else {
            # ipv4
            if ($family != 6) {
               $cv->begin;
               AnyEvent::DNS::a $node, sub {
                  push @res, [$idx, "ipv4", [AF_INET, $type, $proton,
                              pack_sockaddr $port, parse_ipv4 $_]]
                     for @_;
                  $cv->end;
               };
            }

            # ipv6
            if ($family != 4) {
               $cv->begin;
               AnyEvent::DNS::aaaa $node, sub {
                  push @res, [$idx, "ipv6", [AF_INET6, $type, $proton,
                              pack_sockaddr $port, parse_ipv6 $_]]
                     for @_;
                  $cv->end;
               };
            }
         }
      }
      $cv->end;
   };

   # try srv records, if applicable
   if ($node eq "localhost") {
      @target = (["127.0.0.1", $port], ["::1", $port]);
      &$resolve;
   } elsif (defined $service && !parse_address $node) {
      AnyEvent::DNS::srv $service, $proto, $node, sub {
         my (@srv) = @_;

         # no srv records, continue traditionally
         @srv
            or return &$resolve;

         # the only srv record has "." ("" here) => abort
         $srv[0][2] ne "" || $#srv
            or return $cb->();

         # use srv records then
         @target = map ["$_->[3].", $_->[2]],
                      grep $_->[3] ne ".",
                         @srv;

         &$resolve;
      };
   } else {