Messenger

🛡 Messenger for local networks, built in pure C# using TCP/IP, MySQL, and WPF.

🚀 Features

• 🔐 User authentication and registration
• 💬 Personal and group chats
• 📎 File and image sharing
• 👥 Online/offline user statuses
• 🎨 Modern dark-themed UI inspired by Telegram

⚙️ Technologies Used

• .NET 8
• WPF (desktop client)
• TCP/IP
• MySQL with Entity Framework
• Newtonsoft.Json
• SHA-256

📸 Preview

📁 Project Structure

• MessengerApp/ – WPF client application
• MessengerServer/ – Console-based server
• MessengerClientTEST/ – Test client (used for debugging and connection testing)

🧩 Example: TCP Server Core Logic

The server is built on top of raw TCP using TcpListener and handles clients with a custom ClientHandler. Below is a simplified version of the main server loop:

public void Start()
{
    _listener.Start();
    ServerIsRunning = true;
    Console.WriteLine("Server is running...");

    while (ServerIsRunning)
    {
        var clientSocket = _listener.AcceptTcpClient();
        Console.WriteLine("Client connected");

        var clientHandler = new ClientHandler(clientSocket, this, _userService, _groupChatService, _personalChatService);
        Task.Run(async () =>
        {
            try
            {
                await clientHandler.HandleClient();
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Client error: {ex.Message}");
            }
        });
    }
}

👤 Example: ClientHandler User Authentication

Each client is handled by a ClientHandler instance that processes commands in a loop. Here's a simplified excerpt showing how user login and registration are managed:

public async Task HandleLoginAsync(string[] parts)
{
    if (parts.Length < 3)
    {
        await SendMessageAsync("LOGIN_FAILED", "Некоректний формат");
        return;
    }

    string username = parts[1], password = parts[2];
    var user = await _userService.AuthenticateUserAsync(username, password);

    if (user != null)
    {
        UserId = user.Id;
        ThisUser = user;
        _server.AddConnectedClient(UserId, this);
        Name = user.Name;
        Surname = user.Surname!;
        Avatar = user.AvatarImage;
        await SendMessageAsync("LOGIN_SUCCESS", "Авторизація успішна", UserId);
    }
    else
    {
        await SendMessageAsync("LOGIN_FAILED", "Невірний логін або пароль", 0);
    }
}

👩‍💻 Example: Client Connection and Login

This is a simplified example of how the client connects to the server and logs in using TCP streams with BinaryReader/Writer:

public async Task<bool> ConnectAsync()
{
    var config = ReadConfig();
    _client = new TcpClient();
    await _client.ConnectAsync(config.IpAddress, config.Port);

    if (_client.Connected)
    {
        _stream = _client.GetStream();
        _reader = new BinaryReader(_stream, Encoding.UTF8);
        _writer = new BinaryWriter(_stream, Encoding.UTF8);
        return true;
    }
    return false;
}

public async Task<(bool success, string message)> LoginAsync(string username, string password)
{
    if (!Connected)
        return (false, "Not connected to server.");

    lock (_streamLock)
    {
        _writer!.Write($"LOGIN|{username}|{password}");
        _writer.Flush();

        string responseType = _reader!.ReadString();
        string responseMessage = _reader.ReadString();
        UserId = _reader.ReadInt32();

        if (responseType == "LOGIN_SUCCESS")
            Username = username;

        return responseType == "LOGIN_SUCCESS"
            ? (true, responseMessage)
            : (false, responseMessage);
    }
}

🛠 How to Run

1. Start the MessengerServer project.
2. Launch the MessengerApp (WPF client).
3. Make sure the client reads the correct IP and Port from config.json.
4. Register a new user or log in with existing credentials.

📌 Project Status

Under active development. Planned features include real-time messaging, emoji support, notifications, and better error handling.

🔒 Source Code Availability

This repository serves as a portfolio preview of the Messenger project.
The full source code is not publicly available to prevent misuse, but a demo or access for review can be provided upon request.

👤 Author

Andriy Khodakivskiy
Private GitHub repository – not open for public use yet.