Here will be a collection of the simplest possible TCP chat servers, to demonstrate how to write multiuser, multiplexing server software using various techniques.
A yoctochat server will:
- take a single commandline argument, the port to listen on
- open a listening port
- handle multiple connections and disconnections on that port
- receive text on a connection, and forward it on to all other connections
- produce simple output about what its doing
- demonstrate a single IO multiplexing technique as simply as possible
- be well commented!
20+ years ago, during my University days, I started writing little chat servers like this to teach myself C, UNIX, systems programming, internet programming, and so on. I went on to write bigger and better ones. It has been useful knowledge!
Lately, I found myself wanting to experiment with io_uring, and I realised I'd forgotten how the "classic" select() loop is constructed. So I started there, and here we are!