如何使用PHP curl_setopt检查服务器错误类型?

I'm trying to query data from another website by using PHP curl_setopt as below function, But I don't know to valid when my partner sever get any error as below description.

    [Server Error 5xx]
    500="Internal Server Error"
    501="Not Implemented"
    502="Bad Gateway"
    503="Service Unavailable"
    504="Gateway Timeout"
    505="HTTP Version Not Supported"


   public function getNumber() {

        $url = "http://website/PalmHallServer_kl/!queryLuckNumberRecordByPeriods.action";
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: Json'));
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
        $contents = curl_exec($ch);
        $res = false;
        if ($contents) {
            $res = TRUE;
        } else {
            $res = FALSE;
        }
        echo json_encode(array("res" => $res, 'data' => $contents));
    }

First tell curl that you want to see the headers returned

curl_setopt($ch, CURLOPT_HEADER, true); 

Then you can get Response code using

$status = curl_getinfo($ch, CURLINFO_HTTP_CODE);

To see all the information contained in the response headers you can do

print_r(curl_getinfo($ch));