php获取客户端IP

/**
 * @param int $type 返回类型 0返回IP地址 1返回IPV4地址数字
 * @param bool $isAdv 是否进行高级模式获取（有可能被伪装的IP）
 * @return mixed
 */
function get_client_ip($type = 0, $isAdv = true) {
    $type = $type ? 1 : 0;
    static $ip = null;
    if ($ip !== null) {
        return $ip[$type];
    }
    if ($isAdv) { // nginx代理模式下，获取客户端真实IP
        if (isset($_SERVER['HTTP_X_REAL_IP'])) {
            $ip = $_SERVER['HTTP_X_REAL_IP'];
        } elseif (isset($_SERVER['HTTP_CLIENT_IP'])) {
            $ip = $_SERVER['HTTP_CLIENT_IP'];
        } elseif (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
            $arr = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
            $pos = array_search('unknown', $arr);
            if ($pos !== false) {
                unset($arr[$pos]);
            }
            $ip = trim($arr[0]);
        } elseif (isset($_SERVER['REMOTE_ADDR'])) {
            $ip = $_SERVER['REMOTE_ADDR'];
        }
    } elseif (isset($_SERVER['REMOTE_ADDR'])) {
        $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] ?? null;
}