refactor excessively long functions

For readability's sake, we should refactor functions so that they're reasonably short. The screen size is ~80 lines, some functions are >300 lines, which makes it easier to make mistakes. The !432 (merged) added an upper bound limit of 400 statements / 500 lines, but we should do better. These functions exceed the 200 statements / 300 lines limit:

• layer/validate.c:824 function 'validate' 337 statements (threshold 200)
• resolve.c:1310 function 'kr_resolve_produce' 250 statements (threshold 200)
• worker.c:1406 function 'qr_task_step' 221 statements (threshold 200)
• worker.c:1872 function 'worker_process_tcp' 260 statements (threshold 200)
• main.c:425 function 'main' 247 statements (threshold 200)

If readability is the main aim, it mainly depends how the functions are written, and I don't think there's a good automatizable metric for that. It will be good to fit under 200/300, but length itself typically isn't what obstructs my understanding in kresd code...

I'm not sure what do you suggest. This ticket is only about making functions shorter because it's better to have a function that fits on the screen rather than a function that fits on four screens, regardless of what the function does. It's not trying to solve anything else.

To be clear, I do agree it's better.

Maybe @gdemidov would like to take worker_process_tcp and qr_task_step? It's been rewritten recently, and it'd be clearer to follow if sections dealing with different connection states were extracted into separate functions (e.g. close, buffering, new origin response, new client query, ...). Perhaps relevant to #292

mentioned in commit 36731814

added refactoring label

added plan label

marked the checklist item worker.c:1406 function 'qr_task_step' 221 statements (threshold 200) as completed

marked the checklist item worker.c:1872 function 'worker_process_tcp' 260 statements (threshold 200) as completed

Daemon part is more of less done.

removed plan label

Most pressing issues were fixed, we will get to the rest later as time allows.