how to peek at serialized data from QDataStream

[wysota]

Checking for validity of correct type of data is my application's problem. And I understand from the documentation,that corrupted data should change QDataStream's status to QDataStream::ReadCorruptData.. so what other problem there could be?

That you lose sync with the stream and the only thing you can do is disconnect the client. Besides, nobody checks the status of the stream anyway.

I assume possibility of buffer overflow,etc. is taken care of by qt developers.

There is no buffer overflow. Clients can just crash your machine by feeding it more data that the machine has RAM available while often you wait just for a few bytes of data. It is a rare case that your server works on generic data, usually you have some kind of protocol and you know how much data to expect. Relying on the client to provide a size followed by a blob is just asking for trouble.