直播服务的CDN签名机制PHP怎么实现

$signKey = bin2hex(random_bytes(16));

$url = "http://example.com/live/stream.flv"; // 要访问的URL
$expireTime = time() + 300; // 签名过期时间，单位为秒
$signKey = "0123456789abcdef0123456789abcdef"; // 签名密钥

$parsedUrl = parse_url($url);
$path = $parsedUrl["path"];
$query = isset($parsedUrl["query"]) ? $parsedUrl["query"] : "";
$host = $parsedUrl["host"];
$signString = sprintf("%s\n%s\n%s", $path, $query, $expireTime);
$signature = hash_hmac("sha1", $signString, $signKey);

$signedUrl = sprintf("%s?sign=%s&t=%d", $url, $signature, $expireTime);

$ch = curl_init($signedUrl);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
curl_close($ch);