Thinkphp中无法获取用户真实IP

TP6中无法获取到用户真实的IP，无法穿透代理，以下分享一个自用的获取IP的代码，估计TP5中存在同样的问题。

1**
2 * 获得用户的真实IP地址
3 *
4 * @access  public
5 * @return  string
6 */
7function real_ip()
8{
9    static $realip = NULL;
10
11    if ($realip !== NULL)
12    {
13        return $realip;
14    }
15
16    if (isset($_SERVER))
17    {
18        if (isset($_SERVER['HTTP_X_FORWARDED_FOR']))
19        {
20            $arr = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
21
22            /* 取X-Forwarded-For中第一个非unknown的有效IP字符串 */
23            foreach ($arr AS $ip)
24            {
25                $ip = trim($ip);
26
27                if ($ip != 'unknown')
28                {
29                    $realip = $ip;
30
31                    break;
32                }
33            }
34        }
35        elseif (isset($_SERVER['HTTP_CLIENT_IP']))
36        {
37            $realip = $_SERVER['HTTP_CLIENT_IP'];
38        }
39        else
40        {
41            if (isset($_SERVER['REMOTE_ADDR']))
42            {
43                $realip = $_SERVER['REMOTE_ADDR'];
44            }
45            else
46            {
47                $realip = '0.0.0.0';
48            }
49        }
50    }
51    else
52    {
53        if (getenv('HTTP_X_FORWARDED_FOR'))
54        {
55            $realip = getenv('HTTP_X_FORWARDED_FOR');
56        }
57        elseif (getenv('HTTP_CLIENT_IP'))
58        {
59            $realip = getenv('HTTP_CLIENT_IP');
60        }
61        else
62        {
63            $realip = getenv('REMOTE_ADDR');
64        }
65    }
66
67    preg_match("/[\d\.]{7,15}/", $realip, $onlineip);
68    $realip = !empty($onlineip[0]) ? $onlineip[0] : '0.0.0.0';
69
70    return $realip;
71}