PHP通过UTC获取精确时间

    /**
     * 通过UTC获取精确时间，默认为北京时间
     * @param int $timezone
     * @param int $timestamp
     * @return bool|false|string
     */
    public function getutctime($timezone = 8, $timestamp = 0) {
        $fp = fsockopen('time.nist.gov', 13, $err_no, $err_str, 90);
        $t = fread($fp, 2096);
        if (!strlen($t)) return false;
        $arr = explode(" ", $t);
        $t = dateadd('hour', $timezone, strtotime($arr[1] . " " . $arr[2]));
        return $timestamp ? $t : date("Y-m-d H:i:s", $t);
    }