php获取客户端真实IP地址

//获取用户真实ipfunction getIp() {    if (getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown"))        $ip = getenv("HTTP_CLIENT_IP");    else        if (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown"))            $ip = getenv("HTTP_X_FORWARDED_FOR");        else            if (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown"))                $ip = getenv("REMOTE_ADDR");            else                if (isset ($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown"))                    $ip = $_SERVER['REMOTE_ADDR'];                else                    $ip = "unknown";    return ($ip);}