Is it possible to cast struct to another?

Question

Any one could describe how (struct sockaddr *)&server works here? Is it possible to cast bigger struct to smaller struct?

See these structs:

Answer 1

This is C's form of "inheritance" (notice the quotes). This works because C does not care about the underlying data in an address, just what you represent it as.

The function determines what structure it actually is by using the sa_family field, and casting it into the proper sockaddr_in inside the function.