The main issue to me is that conversion, parsing, and validation are scattered throughout the code when they should be in separate, local, sequential steps. Yo

The main issue to me is that conversion, parsing, and validation are scattered throughout the code when they should be in separate, local, sequential steps. You should never be in a situation where you're halfway through allocating memory for an internal structure when suddenly you realize your input is malformed, for three reasons: - In order to make a good decision about what to do next, you need a lot of context: what you need to clean up, what any calling function expects you to do, any internal state you need to update, etc. You either end up passing a lot of extraneous context info around, or you make everything global. - Alternatively you bail with a status code and mutter "yolo" to yourself, or you throw an assert -- but crashing a system daemon with input is the essence of a DoS, so only the truly ignorant or lazy resort to it. - Building a reasonable framework is hard when all your concerns are entwined like this. If at some point you decide asserts on input are bad, it's very hard to change that convention in this code. Essentially all your function signatures and your entire call graph change. There's an extraordinary amount of technical debt here; just look at all the places Lennart had to change the size/offset stuff. The logic for this is scattered all over the place. People have focused on some of the tactical issues -- asserts on input, byte order conversion, etc. -- but the real issue is that when you write code in this style those things don't jump out at you because you have to do them everywhere. If your code had a better separation of concerns, as soon as you saw 'offsetof' in a parsing function you'd immediately see a red flag. It's so much easier to think in these specific contexts, where you're assured previous steps are complete, rather than in every single function having to get the entire conversion/validation/parsing flow correct every single time, keeping the entire thing in your head always.