如何在没有继承的情况下模拟对象（在C中）？

We use a simple object model for our low level networking code at work where struct pointers are passed around to functions which are pretending to be methods. I've inherited most of this code which was written by consultants with passable C/C++ experience at best and I've spent many late nights trying to refactor code into something that would resemble a reasonable structure.We use a simple object model for our low level