TCP Chat Application

A real-time console-based chat application built with .NET using TCP sockets for reliable client-server communication.

Overview

This project implements a multi-user chat system with both public and private messaging capabilities. It consists of two applications:

• Server: Handles client connections, authentication, and message broadcasting.
• Client: Provides a user-friendly console interface for sending and receiving messages.

The application uses raw TCP socket communication with a simple text-based protocol enhanced with JSON for structured message exchange.

Features

• User Authentication: Login with username and password.
• Account Creation: New users are automatically registered on first login.
• Private Messaging: Send private messages to specific users with /msg <username> <message>.
• User Listing: View all currently connected users with the list command.
• Command Help: Display available commands with --help.
• Persistent Storage: All messages and user accounts are stored in MongoDB.
• Timestamp Display: All messages include timestamps for better conversation tracking.

Architecture

Server Components

• TcpServer: Core server class that handles client connections.
• Database: MongoDB integration for user management and message persistence.
• Broadcast: Handles message distribution to connected clients.
• Help: Provides command documentation to users.

Client Components

• TcpClientApp: Main client class with UI handling and server communication.
• Console Input Management: Custom implementation for preserving user input when receiving messages.

Communication Protocol

The application uses a JSON-based protocol for message exchange:

{
  "type": "public_message",
  "sender": "username",
  "content": "message text",
  "timestamp": "10:15:30"
}

Message types include:

• public_message: Broadcast to all users.
• private_message: Sent to a specific user.
• private_confirmation: Confirmation of a sent private message.
• user_list: List of online users.
• error: Error messages.
• help: Command documentation.

Getting Started

Prerequisites

• .NET 9.0 SDK
• MongoDB instance (local or Atlas)

Configuration

1. Configure the MongoDB connection in your settings file (rename database.exemple.json to database.json):

   {
     "ConnectionString": "mongodb+srv://your-connection-string",
     "DatabaseName": "tcp-chat"
   }

2. Run the server:

   cd Server
   dotnet run

3. Run the client:

   cd Client
   dotnet run

Connect to the server by providing the server IP and port (default: 127.0.0.1:5000) inside Program.cs in the Client directory.

Usage

Basic Commands

• Send a public message: Just type your message and press Enter.
• Send a private message: /msg <username> <message>
• List online users: list
• Show available commands: --help
• Exit the application: exit

Authentication

The application provides a simple authentication system:

• If the username doesn't exist, a new account is created.
• If the username exists, the password is validated.
• Multiple login attempts are supported without closing the connection.

Technical Details

• Thread Safety: Console output is protected with locks to prevent corruption.
• Async/Await: Fully asynchronous communication for better performance.
• Error Handling: Robust error handling for network issues and invalid inputs.
• Connection Management: Graceful handling of client disconnections.
• Prompt Preservation: Client UI maintains user input when receiving messages.

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