This project has been created as part of the 42 curriculum by [ababdoul], [Selboukaoui], [mhoussas].

ft_irc

Description

ft_irc is a fully functional IRC (Internet Relay Chat) server implemented in C++98. The goal of the project is to build a server that handles multiple simultaneous client connections, follows the IRC protocol (RFC 1459), and supports real IRC clients such as LimeChat, irssi, or netcat.

The server supports:

• Simultaneous client connections using poll()
• User authentication via password, nickname, and username registration
• Channel management (join, leave, messaging)
• Operator commands (kick, invite, topic, mode)
• Private messaging between users

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Instructions

Requirements

• C++ compiler supporting C++98 (g++ or clang++)
• A Unix-based system (Linux or macOS)
• make

Compilation

make

Execution

./ircserv <port> <password>

Example:

./ircserv 6667 mypassword

Testing with netcat

nc localhost 6667
PASS mypassword
NICK yournick
USER yournick localhost localhost Real_Name
JOIN #general
PRIVMSG #general :Hello everyone!

Testing with a real IRC client (LimeChat / irssi)

• Host: localhost
• Port: 6667
• Server password: the password you used to start the server

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Features

Commands implemented

Command	Description
PASS	Authenticate with server password
NICK	Set or change nickname
USER	Register username and real name
JOIN	Join one or multiple channels (JOIN #a,#b)
PART	Leave one or multiple channels
PRIVMSG	Send a message to a channel or a user
QUIT	Disconnect from the server
KICK	Remove a user from a channel (operator only)
INVITE	Invite a user to a channel
TOPIC	View or set the channel topic
MODE	Set channel or user modes

Channel modes supported

Mode	Description
+i	Invite-only channel
+t	Topic settable by operators only
+k	Channel password (key)
+o	Give/take operator privilege
+l	Set user limit

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Project Structure

ft_irc/
├── header.hpp               — shared includes and declarations
├── main.cpp                 — entry point
├── Makefile
├── README.md
│
├── authentication/
│   ├── authentication.cpp   — registration flow orchestration
│   ├── PASS.cpp             — password authentication
│   ├── NICK.cpp             — nickname registration and validation
│   └── USER.cpp             — username and realname registration
│
├── client/
│   ├── client.cpp           — Client class (poll list + client info)
│   └── client.hpp           — t_info struct and Client class
│
├── server/
│   ├── server.cpp           — main server loop
│   ├── server.hpp           — Server class and declarations
│   ├── channel.hpp          — Channel struct/class
│   ├── utils.cpp            — socket helpers (bind, listen, poll, recv, send)
│   └── welcom.cpp           — welcome replies (001 002 003 004)
│
└── cmds/
    ├── cmds.hpp             — all command function declarations
    ├── parse.cpp            — IRC message parser
    ├── JOIN.cpp             — join channels
    ├── PART.cpp             — leave channels
    ├── PRIVMSG.cpp          — send messages to channels or users
    ├── QUIT.cpp             — disconnect from server
    ├── KICK.cpp             — remove a user from a channel
    ├── INVITE.cpp           — invite a user to a channel
    ├── TOPIC.cpp            — view or set channel topic
    └── MODE.cpp             — channel and user modes

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Resources

IRC Protocol

• Modern IRC documentation — cleaner and more readable reference for commands and numerics

Networking in C/C++

• Beej's Guide to Network Programming — the classic reference for sockets, poll(), recv(), send()
• Linux man pages — poll(2)
• Linux man pages — socket(2)

AI Usage

Claude (claude.ai) was used throughout this project for:

• Architecture design — understanding how to structure the server loop, Client class, and command dispatcher
• Debugging — identifying bugs in poll loop, buffer management, and command parsing
• Command implementation guidance — step-by-step explanation of what each IRC command must do, which numeric replies to send, and edge cases to handle (e.g. multi-channel JOIN, buffer splitting on \r\n)
• IRC protocol understanding — explaining numeric reply codes, the registration flow (PASS -> NICK -> USER), and message format (:prefix COMMAND params :trailing\r\n)
• Code review — reviewing JOIN, PRIVMSG, PART, and QUIT implementations for bugs before testing

AI was used as a learning and debugging tool. All code was written and understood by the team members.