💬 ft_irc

Minimal IRC server written in C++ — networking, sockets, and protocol parsing

About · Usage · Features · What I Learned

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About

ft_irc is a small, student-implemented IRC server that reproduces the core behavior of the Internet Relay Chat protocol (RFC 1459 and common extensions) for learning purposes. The project focuses on:

• low-level network programming with sockets,
• concurrent client handling with non-blocking I/O (poll/select),
• parsing and executing IRC commands,
• implementing channel and user state management,
• robust error handling and graceful disconnects.

See the project subject in the repository for the full specification and mandatory behaviour.

Requirements

• A POSIX-compatible system (Linux, macOS)
• C compiler (gcc / clang)
• Make (Makefile provided)
• No external libraries required (uses standard libc and POSIX APIs)

Build

From the project root:

$ make

This will produce the server binary (e.g. ircserv). Standard Make targets are available:

• make — build
• make clean — remove object files
• make fclean — remove objects and binaries
• make re — fclean + make

Usage

Start the server:

$ ./ircserv <port> <password>

Example:

$ ./ircserv 6667 secretpass

Connecting with an IRC client:

• Using hexchat / irssi:

  /connect -password secretpass 127.0.0.1 6667

• Using netcat / telnet for manual tests (raw protocol):

$ nc -C 127.0.0.1 6667
NICK mynick
USER mynick 0 * :Real Name

After registering (NICK + USER), you can JOIN channels and send messages:

JOIN #channel
PRIVMSG #channel :Hello, world!
PART #channel

The server expects commands terminated by CRLF (\r\n) and follows common IRC reply conventions where applicable.

Features

Implemented behavior typically includes:

• Accepting multiple simultaneous client connections
• Non-blocking I/O and efficient polling loop (select/poll)
• Parsing and handling of core IRC commands:
  • NICK, USER, JOIN, PART, PRIVMSG, NOTICE, PING/PONG, QUIT
• Channel creation and membership management
• Basic message routing between users and channels
• Graceful client disconnect and resource cleanup
• Simple validation and error replies to malformed commands

Behaviors implemented:

• MODE (channel and user modes)
• TOPIC
• KICK
• INVITE
• TOPIC, CHANLIMITS and channel creation rules
• Registration timeout

Testing

• Manual tests with netcat / telnet as above
• Connect multiple clients and verify message routing and channel state
• Verify server handles abrupt client disconnects and malformed input
• Optionally use an IRC client (irssi/weechat) for interactive testing

What I Learned

• First time used Test Driven Development and I saw how it can help me focus my thought and build robust programs
• Low-level network programming with sockets (bind, listen, accept)
• Non-blocking I/O and multiplexing with poll/select
• Protocol design and robust parsing of line-based protocols
• Managing shared server state (users, channels) safely in an event loop
• Debugging networking issues (partial reads/writes, disconnected peers)
• Designing simple but resilient command handling and error reporting