ft_irc

An IRC server implemented in C++98 as part of the 42 School curriculum. Handles multiple concurrent clients over TCP using poll() for multiplexed non-blocking I/O, with RFC 1459 compliant message parsing.

Features

• 12 IRC commands — PASS, NICK, USER, QUIT, PING, JOIN, PART, PRIVMSG, KICK, INVITE, TOPIC, MODE
• 5 channel modes — invite-only (+i), topic restriction (+t), channel key (+k), operator privilege (+o), user limit (+l)
• RFC 1459 message parsing — prefix, command, and parameter extraction with trailing parameter support
• poll()-based non-blocking I/O — all network I/O goes through the poll loop; no direct send/recv outside it
• Authentication flow — three-step registration: PASS → NICK → USER
• Send/receive buffering — partial data handling for fragmented TCP streams (supports nc + Ctrl+D)
• Graceful shutdown — signal handling for SIGINT and SIGQUIT

Requirements

• C++ compiler with C++98 support
• POSIX environment (macOS / Linux)
• Make

Build

make            # Build (parallel, uses all CPU cores)
make clean      # Remove object files
make fclean     # Remove objects and binary
make re         # Full rebuild
make info       # Show build configuration
make help       # Show available targets

Usage

./bin/ircserv <port> <password>

Connecting with an IRC client

# irssi
irssi -c localhost -p 6667 -w mypassword

# WeeChat
/server add local localhost/6667 -password=mypassword
/connect local

# netcat (manual testing)
nc -C localhost 6667
PASS mypassword
NICK mynick
USER mynick 0 * :My Real Name

Supported Commands

Registration

Command	Syntax	Description
PASS	PASS <password>	Authenticate with the server password
NICK	NICK <nickname>	Set or change nickname
USER	USER <username> 0 * :<realname>	Set username and real name
QUIT	QUIT [:<message>]	Disconnect from the server
PING	PING <token>	Keep-alive; server responds with PONG

Channels

Command	Syntax	Description
JOIN	JOIN <channel>[,<channel>] [<key>[,<key>]]	Join one or more channels
PART	PART <channel> [:<message>]	Leave a channel
PRIVMSG	PRIVMSG <target> :<message>	Send a message to a channel or user

Operator

Command	Syntax	Description
KICK	KICK <channel> <nick> [:<reason>]	Remove a user from a channel
INVITE	INVITE <nick> <channel>	Invite a user to a channel
TOPIC	TOPIC <channel> [:<topic>]	Set or query the channel topic
MODE	MODE <channel> <modes> [<params>]	Set or query channel modes

Channel Modes

Mode	Description	Parameter
+i	Invite-only — only invited users can join	—
+t	Topic restricted — only operators can change the topic	—
+k	Channel key — requires a password to join	<key> (set)
+o	Operator privilege — grant or revoke operator status	<nick>
+l	User limit — restrict the maximum number of members	<limit> (set)

Multiple modes can be set in a single command:

MODE #channel +itk-o secretkey nick
MODE #channel +kl secret 10

Authentication Flow

Client                          Server
  │                               │
  │  PASS <password>              │
  │ ───────────────────────────>  │  Validate password
  │                               │
  │  NICK <nickname>              │
  │ ───────────────────────────>  │  Validate + check duplicates
  │                               │
  │  USER <user> 0 * :<real>      │
  │ ───────────────────────────>  │  Set user info
  │                               │
  │  001 RPL_WELCOME              │
  │  002 RPL_YOURHOST             │
  │  003 RPL_CREATED              │
  │  004 RPL_MYINFO               │
  │ <───────────────────────────  │  Registration complete
  │                               │

Unregistered clients can only use PASS, NICK, USER, QUIT, and PING. All other commands return 451 ERR_NOTREGISTERED.

Architecture

Data Flow

recv() → Client::recv_buffer_ → extractLine()
       → Message::parse() → Command::execute() → handler
       → Client::send_buffer_ → poll(POLLOUT) → send()

Class Overview

Class	Responsibility
Server	Owns the listening socket, poll() loop, and client/channel maps. Manages connections, dispatches received data, and handles outgoing writes via POLLOUT.
Client	Represents a connected user. Manages recv/send buffers, authentication state (password, nickname, username), and generates the nick!user@host prefix.
Channel	Represents an IRC channel. Manages members, operators, invite lists, modes, and broadcasts messages to members.
Message	Namespace for RFC 1459 message parsing (parse()) and building (build()).
Command	Namespace containing the command dispatcher (execute()) and all 12 command handlers.

Project Structure

ft_irc/
├── Makefile
├── DEV_DOC.md            # Development documentation
├── FEAT_IRC.md           # IRC feature requirements
├── LICENSE
├── src/
│   ├── main.cpp          # Entry point
│   ├── ft_irc.hpp        # Main header (Global, Cli namespaces)
│   ├── ft_irc.cpp        # ft_irc_main(), version, banner
│   ├── irc_cli.cpp       # CLI argument parsing
│   ├── config.h.in       # Build config template
│   ├── server.hpp        # Server class declaration
│   ├── server.cpp        # Socket, poll loop, client/channel management
│   ├── client.hpp        # Client class declaration
│   ├── client.cpp        # Client buffering, auth state
│   ├── channel.hpp       # Channel class declaration
│   ├── channel.cpp       # Channel member/operator/invite management
│   ├── command.hpp       # Command dispatcher declaration
│   ├── command.cpp       # IRC command handlers
│   ├── message.hpp       # Message parsing declaration
│   ├── message.cpp       # IRC protocol message parsing/building
│   └── osx/
│       └── os.cpp        # macOS platform-specific code
├── tests/
│   ├── test.sh           # Test runner
│   ├── helpers.sh        # Shared test helpers
│   ├── test_registration.sh
│   ├── test_ping.sh
│   ├── test_channel.sh
│   ├── test_operator.sh
│   └── test_errors.sh
├── bin/
│   └── ircserv           # Output binary
└── obj/                  # Build artifacts

Testing

Automated Tests (24 tests)

make && bash tests/test.sh

Test Suite	Tests	Coverage
test_registration.sh	7	PASS, NICK, USER validation and error cases
test_ping.sh	1	PING/PONG keep-alive
test_channel.sh	5	JOIN, PART, PRIVMSG, first-user-is-operator
test_operator.sh	7	KICK, INVITE, TOPIC, MODE (+i, +k, +l)
test_errors.sh	4	Channel errors, permission errors

Individual test suites can be run separately:

bash tests/test_registration.sh
bash tests/test_channel.sh

Manual Testing with netcat

# Terminal 1: Start server
make && ./bin/ircserv 6667 pass

# Terminal 2: Connect and register
nc -C localhost 6667
PASS pass
NICK testuser
USER testuser 0 * :Test User
JOIN #test
PRIVMSG #test :Hello, world!
PART #test :Goodbye
QUIT :Bye

See DEV_DOC.md for the full development documentation.

License

This project is licensed under the MIT License — see the LICENSE file for details.