[SDL] SDLNet_TCP_Recv() returns... null socket?

[Ulrich Eckhardt]

On Saturday 08 September 2007 04:55:20 L-28C wrote:
> result = SDLNet_TCP_Recv(me->Socket, me->Name, 16);
> if (result < 0)
> {
> 	fprintf(stderr, "Couldn't receive player's name: %s.\r\nClosing
> connection", SDLNet_GetError());
> 	SDLNet_TCP_Close(me->Socket);
> 	return -1;
> }
> -------------------------
>
> I used GDB to find out that, before that snippet, me->Socket is valid,
> but after it's null.

I bet that you have a buffer overrun here. The receive function does 
definitely not modify the value of the first argument passed to it, because 
it can't. However, you are passing a related pointer (me->Name) to it, and if 
that buffer is too small, it will happily overwrite anything related there. 
Also, I wouldn't hard-code the size 16 there, because it means that you have 
to keep several places where this constant is used in sync. Use a constant 
with a name, or maybe a macro, or use 'sizeof me->Name'. Also don't forget to 
NUL-terminate the string.

Uli