=item reuse => $seconds

The number of seconds (default: C<300>) that a query id cannot be re-used
after a timeout. If there was no time-out then query ids can be reused
immediately.

=back

=cut

sub new {
   my ($class, %arg) = @_;

   my $self = bless {
      server  => [],
      timeout => [2, 5, 5],
      search  => [],
      ndots   => 1,
      max_outstanding => 10,
      reuse   => 300,
      %arg,
      reuse_q => [],
   }, $class;

   # search should default to gethostname's domain
   # but perl lacks a good posix module

   # try to create an ipv4 and an ipv6 socket
   # only fail when we cannot create either
   my $got_socket;

   Scalar::Util::weaken (my $wself = $self);

   if (socket my $fh4, AF_INET , &Socket::SOCK_DGRAM, 0) {
      ++$got_socket;

      AnyEvent::Util::fh_nonblocking $fh4, 1;
      $self->{fh4} = $fh4;
      $self->{rw4} = AnyEvent->io (fh => $fh4, poll => "r", cb => sub {
         if (my $peer = recv $fh4, my $pkt, MAX_PKT, 0) {
            $wself->_recv ($pkt, $peer);
         }
      });
   }

   if (AF_INET6 && socket my $fh6, AF_INET6, &Socket::SOCK_DGRAM, 0) {
      ++$got_socket;

      $self->{fh6} = $fh6;
      AnyEvent::Util::fh_nonblocking $fh6, 1;
      $self->{rw6} = AnyEvent->io (fh => $fh6, poll => "r", cb => sub {
         if (my $peer = recv $fh6, my $pkt, MAX_PKT, 0) {
            $wself->_recv ($pkt, $peer);
         }
      });
   }

   $got_socket
      or Carp::croak "unable to create either an IPv4 or an IPv6 socket";

   $self->_compile;

   $self
}

=item $resolver->parse_resolv_conv ($string)

Parses the given string as if it were a F<resolv.conf> file. The following
directives are supported (but not necessarily implemented).

C<#>-style comments, C<nameserver>, C<domain>, C<search>, C<sortlist>,
C<options> (C<timeout>, C<attempts>, C<ndots>).

Everything else is silently ignored.

=cut

sub parse_resolv_conf {
   my ($self, $resolvconf) = @_;

   $self->{server} = [];
   $self->{search} = [];

   my $attempts;

   for (split /\n/, $resolvconf) {
      if (/^\s*#/) {
         # comment
      } elsif (/^\s*nameserver\s+(\S+)\s*$/i) {
         my $ip = $1;
         if (my $ipn = AnyEvent::Socket::parse_address ($ip)) {
            push @{ $self->{server} }, $ipn;
         } else {
            warn "nameserver $ip invalid and ignored\n";
         }
      } elsif (/^\s*domain\s+(\S*)\s+$/i) {
         $self->{search} = [$1];
      } elsif (/^\s*search\s+(.*?)\s*$/i) {
         $self->{search} = [split /\s+/, $1];
      } elsif (/^\s*sortlist\s+(.*?)\s*$/i) {