扩展 Input 库解决 Codeigniter 在中国的 IP 地址问题

MY_Input.php

<?php  if (!defined('BASEPATH')) exit('No direct script access allowed');

/**
 * 扩展的 Input 库
 * @author Luyu<luyu.zhang@autotiming.com>
 */
class MY_Input extends CI_Input
{

    function __construct()
    {
        parent::__construct();
    }

    /**
     * 解决 CI 获取 IP 地址的问题
     * @author Luyu<luyu.zhang@autotiming.com>
     * @return string
     */
    public function ip_address()
    {
        if ($this->ip_address !== FALSE) {
            return $this->ip_address;
        }

        // TODO: $proxy_ips

        if (isset($_SERVER['HTTP_CDN_SRC_IP']) && !empty($_SERVER['HTTP_CDN_SRC_IP'])) {
            $correct_ip_address = $_SERVER['HTTP_CDN_SRC_IP'];
        } else if (isset($_SERVER["HTTP_X_FORWARDED_FOR"]) && !empty($_SERVER["HTTP_X_FORWARDED_FOR"]))
            $correct_ip_address = $_SERVER["HTTP_X_FORWARDED_FOR"];
        else if (isset($_SERVER["HTTP_CLIENT_IP"]) && !empty($_SERVER["HTTP_CLIENT_IP"]))
            $correct_ip_address = $_SERVER["HTTP_CLIENT_IP"];
        else if (isset($_SERVER["REMOTE_ADDR"]) && !empty($_SERVER["REMOTE_ADDR"]))
            $correct_ip_address = $_SERVER["REMOTE_ADDR"];
        else
            $correct_ip_address = '0.0.0.0';

        $this->ip_address = $correct_ip_address;

        if (!$this->valid_ip($this->ip_address)) {
            $this->ip_address = '0.0.0.0';
        }

        return $this->ip_address;
    }
}