Right off the bat, I see multiple instances of str* functions where strn* functions should be used. I'm also wondering about this variable "server" which seems to have an unknown definition. There are lots of gotos, and many other deferred high-quality conventions, such as explicit parenthesis in comparisons, re-ordered fields in comparisons, chains of else ifs, where a switch would be preferable.

I also see lots of prototypes (all?!) defined at the top of the file instead of in a header file. They could be made static.

Also, the generic type "int" isn't a good idea because it can change, it helps avoid porting problems to specify the size (int32_t, uint64_t, etc.)

And the memcpy()'s should be changed to memcpy_s().

On the bright side, the comments are quite good and plentiful. Refreshing!