voidnet

UDP Chat System (Work in Progress)

This project is a UDP-based chat system written in C++.
It provides a lightweight server and client that communicate over UDP sockets while experimenting with reliability mechanisms such as acknowledgments (ACKs).

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✨ Features

✅ Implemented

• Server

  • Creates a UDP socket and binds to a given IP/port.
  • Receives MessagePacket and AckPacket structures from clients.
  • Tracks connected clients (client_list).
  • Broadcasts messages to all clients except the sender.
  • Immediately sends ACKs back to the message sender.
  • Runs a dedicated packet listener thread (RegisterReceiver).

• Client

  • Connects to the server using UDP.
  • Sends an initial handshake (null byte) for registration.
  • Listens for incoming messages in a background thread.
  • Prints server-broadcasted messages.
  • Sends messages typed by the user.
  • Implements ACK sending when receiving MessagePackets.

🔧 In Progress

• Full reliable ACK system to guarantee delivery.
• Queueing and splitting long messages (addToQueue + mheader integration).
• Decoder for handling structured input before sending packets.
• Better buffer and error handling.
• More robust client management (timeouts, disconnects).

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📦 Packet Structures

struct MessagePacket {
    uint32_t type;   // MESSAGE
    uint32_t seq;    // Sequence number
    uint32_t size;   // Payload size
    char data[256];  // Message
};

struct AckPacket {
    uint32_t type;   // ACK
    uint32_t seq;    // Sequence number being acknowledged
};

🛠️ Build & Run

Requirements Linux / Unix-like environment

GNU Make

g++ (C++17 or later)

POSIX sockets (arpa/inet.h, netinet/in.h, sys/socket.h)

Build From the repo root, simply run:

make

This builds both the server (udp_server) and the client (udp_client).

To build them separately:

make udp_server
make udp_client

To clean build artifacts:

make clean

• Run server Start the server:

./udp_server

• Run one or more clients:

./udp_client

Clients can now send messages, which the server broadcasts to all connected clients (excluding the sender).

📂 Project Structure

.
├── client.cpp
├── server.cpp
├── mheader/
│   └── mheader.h
│   └── mheader_encoder.cpp
└── Makefile