function to_ipv4($ip) {
    $inet_pton = inet_pton($ip);
    if ($inet_pton) {
        $ip_number = '';
        foreach (unpack('C*', $inet_pton) as $byte) {
            $ip_number .= str_pad(decbin($byte), 8, '0', STR_PAD_LEFT);
        }
        return long2ip((int)base_convert(ltrim($ip_number, '0'), 2, 10));
    }
    return false;
}