IRC server

The challenge

Build a server compatible with a real IRC client, without threads or additional processes, using a single poll() call to accept connections, receive data, and send responses to multiple clients simultaneously.

Technical work

The server keeps state for each client, reconstructs complete lines from the TCP stream, interprets commands, and generates responses in the IRC protocol format.

The work covers:

• Registration through PASS, NICK, and USER.
• Input and output buffers for partial operations.
• Numeric replies and IRC prefixes.
• A channel and client membership model.
• Channel commands such as JOIN, TOPIC, INVITE, KICK, and MODE.
• Tests with real clients, netcat, and automated cases.

A key decision

TCP does not preserve message boundaries. A recv() call can return half a command or several commands together. Each client therefore needs a persistent buffer, and the server only processes a command after finding its \r\n terminator.

Status

This is a team project and remains in development. The portfolio documentation will be updated as the channel commands and their tests are completed.