Quote Originally Posted by Affenbrotbaum View Post
Excuse my ignorance wysota, but what's wrong with it? I've done testing on it and seems to work with multiple concurrent connections without leaking any memory.
It works only when you receive data you expect in a form you expect and amount you expect.

For example you are reading a block size and then discarding all data already read if there is not enough data available in the socket. Next time you get the signal when the rest of the data arrives but since you are not waiting for the data anymore, you will try to synchronize the data stream again which will obviously fail because there is some data from the previous block still left in the socket.

And provided you even fix it and have a buffer that will store all the incoming data before processing it, what if someone sends you a block size of 2GB? Are you going to buffer 2GB of data in your application for each incoming connection? What if you get 10 such connections? Do you have 20GB of memory in your machine?

If you have to use QDataStream, you synchronize it only once when the connection is established and you should closely monitor the status of the stream and at the first sign of lost synchro, you have to immediately drop the connection.