PHP獲取真實IP地址

<?php

function get_client_ipaddress($type = 0)
{
    $type = $type ? 1 : 0;
    static $ip = NULL;
    if ($ip !== NULL)
        return $ip[$type];
    if ($_SERVER['HTTP_X_REAL_IP']) { //nginx 代理模式下，獲取客戶端真實IP
        $ip = $_SERVER['HTTP_X_REAL_IP'];
    } elseif (isset($_SERVER['HTTP_CLIENT_IP'])) { //客戶端的ip
        $ip = $_SERVER['HTTP_CLIENT_IP'];
    } elseif (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) { //瀏覽當前頁面的用戶計算機的網關
        $arr = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
        $pos = array_search('unknown', $arr);
        if (false !== $pos)
            unset($arr[$pos]);
        $ip = trim($arr[0]);
    } elseif (isset($_SERVER['REMOTE_ADDR'])) {
        $ip = $_SERVER['REMOTE_ADDR']; //瀏覽當前頁面的用戶計算機的ip地址
    } else {
        $ip = $_SERVER['REMOTE_ADDR'];
    }
    // IP地址合法驗證
    $long = sprintf("%u", ip2long($ip));
    $ip   = $long ? array(
        $ip,
        $long
    ) : array(
        '0.0.0.0',
        0
    );
    return $ip[$type];
}

?>

直接上代碼。