UDP Chat

A simple peer-to-peer UDP chat application for Windows written in C++.

Features

• Real-time messaging over UDP
• Peer-to-peer communication
• Preserves partially typed input when messages arrive
• Graceful shutdown using Ctrl+C
• No central server required
• No third-party dependencies

Requirements

Operating System

• Windows 10 or newer

Compiler

Any C++17-compatible Windows compiler.

Tested with:

• MinGW-w64

Should also work with:

• Microsoft Visual Studio (MSVC)
• MSYS2 UCRT64
• MSYS2 MINGW64

Libraries

Only standard Windows libraries are required:

• Winsock2 (ws2_32)
• Windows Console API

No external dependencies are needed.

Setup

git clone https://github.com/acdhemtos/udp-chat.git
cd udp-chat
cd code
g++ main.cpp network.cpp console.cpp -o ../chat.exe -std=c++17 -lws2_32
cd ../

The Compiler specific command may be different.

Running

The application accepts three command-line arguments:

chat.exe <local_port> <peer_ip> <peer_port>

Parameters

Parameter	Description
local_port	Port this instance listens on
peer_ip	IP address of the remote peer
peer_port	Port the remote peer listens on

Local Testing

Open two terminal windows.

Terminal 1

chat.exe 5000 127.0.0.1 5001

Terminal 2

chat.exe 5001 127.0.0.1 5000

Messages typed in either terminal will appear in the other.

Demo

Exiting

You can exit the application by pressing Ctrl+C.

UDP Notes

Because UDP is connectionless:

• Delivery is not guaranteed.
• Packets may arrive out of order.
• Packets may be lost.
• There is no retransmission mechanism.

Firewall

The first time the application runs, Windows Firewall may display a prompt.

If you want to communicate across machines, allow access on the desired network type.

Communicating Across Machines

Assume:

Machine	IP Address
A	192.168.1.10
B	192.168.1.25

Machine A

chat.exe 5000 192.168.1.25 5001

Machine B

chat.exe 5001 192.168.1.10 5000

Both machines must:

• Be reachable on the network
• Allow UDP traffic through the firewall
• Use matching peer ports

Limitations

Current version does not include:

• Message delivery guarantees
• Encryption
• Authentication
• Usernames
• File transfer
• Group chat
• Message history