P2P Chat with Registration and Bridging

This repository contains a minimal peer-to-peer chat program that uses a central server for registration and bridging, then lets clients connect directly to each other for real-time text chat. The goal of this project was to learn about socket programming and basic protocol concepts, and was completed during my Introduction To Networking course.

---

Overview

• Server (server.py):
  • Maintains a list of connected clients (client ID, IP, port).
  • Accepts REGISTER, BRIDGE, and INFO requests from clients.
  • Provides bridging info (IP and port) of another client so a direct, peer-to-peer chat can be established.
• Client (client.py):
  • Registers itself with the server using /register.
  • Requests another client’s IP/port using /bridge.
  • Opens a listening socket to accept inbound connections.
  • Can initiate an outbound connection to another client, sending and receiving chat messages directly over TCP.

---

Goals

• Educational Objective:
• Practice socket programming in Python.
• Explore how protocols introduce endpoints for direct communication.
• Understand multi-threaded designs necessary for real-time, two-way data exchange.
• To have fun! :)

---

Instructions

1. Setup

• Install Python 3 on your system.
• Clone this repository or download the server.py and client.py files.

2. Run the Server

python server.py

The server listens on 127.0.0.1:5555 by default.

3. Run a Client

python client.py <clientID> <listenPort> 127.0.0.1:5555

Example:

python client.py alice 5556 127.0.0.1:5555

4. Commands

Command	Description
/register	Registers this client with the server.
/info	Requests a list of all known clients.
/bridge	Requests another client's IP/Port for direct connection.
/chat IP:PORT	Connects directly to a peer’s chat socket.
/msg <text>	Sends a text message to the connected peer.
/quit	Closes the client.

5. Running Multiple Clients

• Run another client in a new terminal:

python client.py bob 5557 127.0.0.1:5555

---

Example Usage Flow

On Client A (Alice): Register with the server. /register
On Client B (Bob): Register as well. /register
On Client A: Request another client’s info. /bridge
On Client A: Connect to Bob. /chat 127.0.0.1:5557
On Client A: Send a message. /msg Hello Bob!
On Client B: Receives and sees the message. ---

Quitting

• Client: Type /quit at the prompt.
• Server: Press CTRL + C in the terminal.

---

Learning Outcomes

• Socket Programming: Experience with both server and client TCP sockets in Python.
• Multi-Threading: Used separate threads for listening and sending, avoiding Windows console issues.
• Protocol Design: Implemented custom message headers (REGISTER, BRIDGE, INFO) to establish communication.
• P2P Communication: Demonstrated how a server can facilitate direct peer-to-peer chat.

This project serves as a simple demonstration of how clients can register with a central service and then connect peer-to-peer using minimal protocol logic.