relay

Relay

> A multi-client terminal-based chat application built from the ground up using TCP sockets and concurrency.

Objective

Build a client-server chat system where multiple users can connect through their terminals and communicate in real time.

The project should primarily demonstrate:

• TCP/IP networking
• Linux socket programming
• Concurrent client handling
• Thread synchronization
• Client-server architecture
• Basic protocol design
• Systems level C programming

This project is not intended to compete with production chat applications.

Technology Choice

Component	Technology
Language	C
Network	TCP/IP
API	POSIX sockets
Concurrency	POSIX threads
Synchronization	Mutexes and condition variables
Operating System	Linux
Build	Make
Debugging	GDB
Testing	Manual + basic automated tests
Version Control	Git

MVP Features

The first complete version will support:

1. Connection

Client -> TCP -> Server

• Server listens on a configurable port.
• Multiple clients can connect.
• Each client recieves a dedicated server thread.

2. Usernames

Username: akash

• Each client must provide a unique username upon connection.

3. Broadcast

> Hello, Everyone!

Other connected user recieve:

[akash]: Hello, Everyone!

4. Private messaging

> /msg rahul Hey, how are you?

5. User list

> /users

Example output:

Connected users:
- akash
- rahul
- priya

6. Commands

/help
/users
/msg <username> <message>
/quit