sub DottedQuadToLong {
    my $ip_str = shift;
    return 0 unless $ip_str =~ /^\s*(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\s*$/;
    my $ip = 0;
    foreach my $quad ($1,$2,$3,$4){
      return 0 if ($quad > 255);
      $ip = $ip * 256 + $quad;
    }
    return $ip;
}