获取客户端的ip地址

/**
 * 获取客户端IP地址
 * @param int $type 返回类型 0 返回IP地址 1 返回IPV4地址数字
 * @return mixed
 */
function get_client_ip($type = 0)
{
    $type = $type ? 1 : 0;
    static $ip = null;
    if ($ip !== null) {
        return $ip[$type];
    }

    if (isset($_SERVER['HTTP_X_REAL_IP'])) {
        //nginx 代理模式下，获取客户端真实IP
        $ip = $_SERVER['HTTP_X_REAL_IP'];
    } elseif (isset($_SERVER['HTTP_CLIENT_IP'])) {
        //客户端的ip
        $ip = $_SERVER['HTTP_CLIENT_IP'];
    } elseif (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
        //浏览当前页面的用户计算机的网关
        $arr = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
        $pos = array_search('unknown', $arr);
        if (false !== $pos) {
            unset($arr[$pos]);
        }
        $ip = trim($arr[0]);
    } else {
        //浏览当前页面的用户计算机的ip地址
        $ip = $_SERVER['REMOTE_ADDR'];
    }

    //IP地址合法验证
    $long = sprintf("%u", ip2long($ip));
    $ip = $long ? [$ip, $long] : ['0.0.0.0', 0];

    return $ip[$type];
}