How to stop the loop if fread passed all the data?

Question

PHP

I receive data of 16 bytes from the socket and write them to a string. How do I know that fread has passed all the data and then stop the while loop?

Tried using feof function but doesn't work

$socket = stream_socket_client($ip . ":" . $port, $errno, $errstr, 10, STREAM_CLIENT_CONNECT);
stream_set_timeout($socket, 10);

$data = "";
while(/* код для остановки */) {
   $data .= fread($socket, 16);
}
return $data;