💬 ft_irc

An IRC server that actually works.

A fully functional Internet Relay Chat server written in C++98,
implementing the IRC protocol (RFC 2812) with authentication, channels,
operator privileges, and bonus features including a bot and file transfer.

📌 Note: This is a collaborative project. The original repository is Abdellatif404/Internet-Relay-Chat. This fork showcases my contributions while maintaining full attribution to the team.

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📋 Table of Contents

• About
• The IRC Protocol
• Features
• Architecture
• Commands
• Getting Started
• Usage Examples
• Bonus Features
• Technical Details
• Team & Contributions
• Author

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💡 About

ft_irc is a 42 School project that requires building an IRC server from scratch in C++98. The server must handle multiple simultaneous clients using non-blocking I/O and epoll() for event-driven networking.

What Is IRC?

Internet Relay Chat (IRC) is a real-time text messaging protocol from 1988 — the grandfather of modern chat systems like Slack and Discord.

                     IRC ARCHITECTURE

   Client A ─────┐
                  │
   Client B ─────┼────→  IRC SERVER  ←────── Client D
                  │       (ircserv)
   Client C ─────┘         port 6667

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📡 The IRC Protocol

Our server implements RFC 2812 — the IRC client protocol specification:

┌──────────────────────────────────────────────┐
│            IRC MESSAGE FORMAT                 │
│                                              │
│  :<prefix> <command> <params> :<trailing>     │
│                                              │
│  Example:                                    │
│  :nick!user@host PRIVMSG #channel :Hello!    │
│                                              │
│  Max message length: 512 bytes (including    │
│  the CR-LF terminator)                       │
└──────────────────────────────────────────────┘

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✨ Features

• ✅ Authentication — password-protected server access
• ✅ Nicknames & Users — NICK/USER registration per RFC
• ✅ Channels — create, join, leave, and manage channels
• ✅ Private Messages — direct user-to-user messaging
• ✅ Channel Modes — invite-only, topic lock, key, user limit
• ✅ Operator Privileges — KICK, INVITE, TOPIC, MODE
• ✅ Non-blocking I/O — epoll() event-driven architecture
• ✅ Multiple Clients — concurrent connections without threads
• ✅ Graceful Handling — partial messages, disconnections, errors

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🏗️ Architecture

┌──────────────────────────────────────────────┐
│              SERVER ARCHITECTURE              │
│                                              │
│  ┌──────────┐     ┌──────────────────────┐  │
│  │  epoll() │ ──→ │  Event Loop          │  │
│  │  wait    │     │  • Accept new clients │  │
│  └──────────┘     │  • Read from sockets  │  │
│       ↑           │  • Parse commands     │  │
│       │           │  • Execute & respond  │  │
│  ┌──────────┐     └──────────────────────┘  │
│  │  Socket  │              │                 │
│  │  fd pool │              ▼                 │
│  └──────────┘     ┌──────────────────────┐  │
│                   │  Command Dispatcher   │  │
│                   │  NICK, JOIN, PRIVMSG  │  │
│                   │  KICK, MODE, TOPIC... │  │
│                   └──────────────────────┘  │
└──────────────────────────────────────────────┘

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📜 Commands

Connection & Registration

Command	Syntax	Description
PASS	PASS <password>	Authenticate with server password
NICK	NICK <nickname>	Set or change nickname
USER	USER <user> 0 * :<realname>	Register username
QUIT	QUIT [:<message>]	Disconnect from server

Channel Operations

Command	Syntax	Description
JOIN	JOIN <#channel> [key]	Join a channel
PART	PART <#channel> [:<message>]	Leave a channel
TOPIC	TOPIC <#channel> [:<topic>]	View/set channel topic
NAMES	NAMES <#channel>	List users in channel

Messaging

Command	Syntax	Description
PRIVMSG	PRIVMSG <target> :<message>	Send message to user/channel
NOTICE	NOTICE <target> :<message>	Send notice (no auto-reply)

Operator Commands

Command	Syntax	Description
KICK	KICK <#channel> <user> [:<reason>]	Remove user from channel
INVITE	INVITE <user> <#channel>	Invite user to channel
MODE	MODE <#channel> <+/-flags> [params]	Set channel modes

Channel Modes

Mode	Flag	Description
Invite-only	+i	Only invited users can join
Topic lock	+t	Only operators can change topic
Channel key	+k <key>	Password-protected channel
User limit	+l <count>	Maximum number of users
Operator	+o <nick>	Grant/revoke operator status

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🚀 Getting Started

Compilation

make            # Build the server
make clean      # Remove object files
make fclean     # Full clean
make re         # Rebuild

Running the Server

./ircserv <port> <password>

# Example
./ircserv 6667 mypassword

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🎮 Usage Examples

Connecting with irssi

irssi -c localhost -p 6667 -w mypassword

Connecting with netcat

nc -C 127.0.0.1 6667
PASS mypassword
NICK mynick
USER myuser 0 * :Real Name
JOIN #general
PRIVMSG #general :Hello everyone!

Connecting with HexChat

1. Add new network → Server: localhost/6667
2. Set server password: mypassword
3. Connect and join channels

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🎁 Bonus Features

IRC Bot

An automated bot that responds to commands and provides utility functions within channels.

DCC File Transfer

Direct Client-to-Client file transfer — allows users to send files directly to each other through the IRC server.

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🔧 Technical Details

Aspect	Implementation
I/O Model	Non-blocking with epoll()
Standard	C++98 strict compliance
Concurrency	Single-threaded, event-driven
Protocol	RFC 2812 (IRC Client Protocol)
Max Message	512 bytes including CRLF
Compatible Clients	irssi, HexChat, WeeChat, netcat

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👥 Team & Contributions

This was a collaborative 42 project. Full attribution to all team members:

Member	GitHub	Contributions
Abdellatif	@Abdellatif404	Server core, channel management
Adil Bourji	@adi7-x	Command parsing, operator privileges, testing

🔗 Original repository: Abdellatif404/Internet-Relay-Chat

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👤 Author

Adil Bourji — @adi7-x

_{42 School · Common Core · Networking · C++}