请问token验证失败是哪里的问题

代码如下：

$timestamp = $_GET['timestamp'];

$nonce     = $_GET['nonce'];

$token     = 'xiexie';

$signature = $_GET['signature'];

$array     = ();

$array     = $array($timestamp,$nonce,$token);

sort($array);

$tmpstr    = implode('',$array);

$tmpstr    = sha1($tmpstr);

if($tmpstr == $signature){

echo $_GET['echostr'];

exit;

}