function real_ip()
{
    static $realip = null;
    if ($realip !== null)
    {
        return $realip;
    }
    if (isset($_server))
    {
        if (isset($_server['http_x_forwarded_for']))
        {
            $arr = explode(',', $_server['http_x_forwarded_for']);
            foreach ($arr as $ip)
            {
                $ip = trim($ip);
                if ($ip != 'unknown')
                {
                    $realip = $ip;
                    break;
                }
            }
        }
        elseif (isset($_server['http_client_ip']))
        {
            $realip = $_server['http_client_ip'];
        }
        else
        {
            if (isset($_server['remote_addr']))
            {
                $realip = $_server['remote_addr'];
            }
            else
            {
                $realip = '0.0.0.0';
            }
        }
    }
    else
    {
        if (getenv('http_x_forwarded_for'))
        {
            $realip = getenv('http_x_forwarded_for');
        }
        elseif (getenv('http_client_ip'))
        {
            $realip = getenv('http_client_ip');
        }
        else
        {
            $realip = getenv('remote_addr');
        }
    }
    preg_match(/[\d\.]{7,15}/, $realip, $onlineip);
    $realip = !empty($onlineip[0]) ? $onlineip[0] : '0.0.0.0';
    return $realip;
}