关于获取用户真实 ip 问题，下面代码可靠性 ok 吗？

if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
    $arr    =   explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
    $pos    =   array_search('unknown',$arr);
    if(false !== $pos) unset($arr[$pos]);

    foreach ($arr as $k => $v) {
    if(preg_match("/^10\.|^19\d{1}\.|^17\d{1}\./", trim($v))) {
    	unset($arr[$k]);
    }
    }
    if(!count($arr)) throw new \Exception('ip 获取失败', 403);
    // 过滤完数据 获取最后一个地址
    $ip = trim(end($arr));

} elseif (isset($_SERVER['HTTP_CLIENT_IP'])) {
	$ip     =   $_SERVER['HTTP_CLIENT_IP'];
} elseif (isset($_SERVER['REMOTE_ADDR'])) {
	$ip     =   $_SERVER['REMOTE_ADDR'];
}