Refactoring C: Implementing Parsing

So far in this series, I’ve done a whole lot of work around building the basic infrastructure of just building a trivial echo server with SSL. But the protocol I have in mind is a lot more complex. Let’s get started with actually implementing the parsing of messages.
To start with, we need to implement parsing of lines. In C, this is actually a decidedly non-trivial operation, because you need to read the data from the network into someplace and parse it. This area is rife with errors, so that is going to be fun.