C++ TCP Socket Chat System

Multi-client chat application built with C++17, TCP/IP sockets, and multithreading
Cross-platform support for Windows (Winsock2) and Linux (POSIX sockets)

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Overview

This project is a production-style multi-client TCP chat system developed in C++17 to demonstrate practical knowledge of:

• TCP/IP socket programming
• Client-server architecture
• Multithreading and concurrency
• Cross-platform systems development
• Structured logging and debugging
• Modular software design

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Why this project stands out

Unlike a basic single-user socket demo, this project supports:

• Multiple clients connecting to one server
• Real-time message broadcasting
• Username-based join and leave notifications
• Thread-per-client communication handling
• Logging for easier debugging and observability
• Cross-platform support using:
  • Winsock2 on Windows
  • POSIX sockets on Linux/macOS

This makes the project much closer to a real-world networking/system software mini-build than a simple classroom implementation.

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Key Features

• Multi-client TCP chat server
• Real-time client-server communication
• Username-based session handling
• /list command to display active users
• /quit command for graceful disconnect
• Broadcast messaging across connected clients
• Timestamped logging to .log files
• Cross-platform socket abstraction
• Clean folder structure and modular code organization
• Build support via g++ and CMake
• GitHub Actions CI workflow

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Tech Stack

Area	Technology
Language	C++17
Networking	Winsock2 (Windows), POSIX sockets (Linux/macOS)
Concurrency	std::thread, std::mutex
Build	CMake, g++
Logging	File-based timestamped logs
Platform	Windows, Linux, macOS

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Architecture

High-Level Flow

+------------------+        TCP Connection        +------------------+
|   Client 1       |  ------------------------->  |                  |
| (chat_client)    |                              |                  |
+------------------+                              |                  |
                                                  |                  |
+------------------+        TCP Connection        |    Chat Server   |
|   Client 2       |  ------------------------->  |   (chat_server)  |
| (chat_client)    |                              |                  |
+------------------+                              |                  |
                                                  |                  |
+------------------+        TCP Connection        |                  |
|   Client N       |  ------------------------->  |                  |
| (chat_client)    |                              +------------------+
+------------------+

Internal Design

• server_main.cpp starts the server on a configurable port.
• chat_server.cpp manages connections, receives messages, and broadcasts them.
• client_main.cpp starts a client with host, port, and username.
• chat_client.cpp handles sending input and receiving server messages concurrently.
• platform.hpp provides cross-platform socket compatibility.
• logger.cpp writes timestamped logs for debugging and tracking activity.

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Project Structure

cpp-tcp-socket-chat/
├── include/
│   ├── platform.hpp
│   ├── chat_server.hpp
│   ├── chat_client.hpp
│   ├── logger.hpp
│   └── utils.hpp
├── src/
│   ├── server_main.cpp
│   ├── client_main.cpp
│   ├── chat_server.cpp
│   ├── chat_client.cpp
│   ├── logger.cpp
│   └── utils.cpp
├── screenshots/
│   ├── 1socket.png
│   ├── 2socket.png
│   └── 3socket.png
├── .github/
│   └── workflows/
│       └── ci.yml
├── CMakeLists.txt
└── README.md

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Build Instructions

Windows (MSYS2 / g++)

g++ -std=c++17 -Iinclude src/server_main.cpp src/chat_server.cpp src/logger.cpp src/utils.cpp -o chat_server.exe -lws2_32 -pthread

g++ -std=c++17 -Iinclude src/client_main.cpp src/chat_client.cpp src/logger.cpp src/utils.cpp -o chat_client.exe -lws2_32 -pthread

Linux / macOS

g++ -std=c++17 -Iinclude src/server_main.cpp src/chat_server.cpp src/logger.cpp src/utils.cpp -o chat_server -pthread

g++ -std=c++17 -Iinclude src/client_main.cpp src/chat_client.cpp src/logger.cpp src/utils.cpp -o chat_client -pthread

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Quick Start

Terminal 1 — Start Server

.\chat_server.exe 9090

Terminal 2 — Start Client 1

.\chat_client.exe 127.0.0.1 9090 smeet

Terminal 3 — Start Client 2

.\chat_client.exe 127.0.0.1 9090 guest2

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Supported Commands

Command	Description
/list	Shows currently connected users
/quit	Gracefully disconnects from the chat
any text	Sends a broadcast message to connected clients

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Demo Output

Terminal 1 — Server

Starting Chat Server on port 9090...
[2026-05-23 14:47:21] [INFO ] Server listening on port 9090
[2026-05-23 14:47:21] [INFO ] Waiting for clients...
[2026-05-23 14:47:44] [INFO ] New connection from 127.0.0.1
[2026-05-23 14:47:44] [INFO ] smeet joined from 127.0.0.1
[2026-05-23 14:48:05] [INFO ] New connection from 127.0.0.1
[2026-05-23 14:48:05] [INFO ] guest2 joined from 127.0.0.1

Terminal 2 — Client 1

[2026-05-23 14:47:44] [INFO ] Connected to 127.0.0.1:9090 as smeet
=== Connected as [smeet] ===
Commands: /list  /quit  or type any message
[server] Welcome, smeet!
[server] guest2 joined from 127.0.0.1

Terminal 3 — Client 2

[2026-05-23 14:48:05] [INFO ] Connected to 127.0.0.1:9090 as guest2
=== Connected as [guest2] ===
Commands: /list  /quit  or type any message
[server] Welcome, guest2!

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Screenshots

Terminal 1 — Server View

Terminal 2 — Client 1 View

Terminal 3 — Client 2 View

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Engineering Highlights

This project demonstrates:

• Socket programming using TCP
• Systems-level C++ development
• Cross-platform networking compatibility
• Concurrent client handling
• Practical debugging through logs
• Reusable modular code structure
• Command-driven terminal application design

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Future Improvements

• Private messaging with /msg <username> <message>
• File transfer between clients
• Persistent chat history
• User authentication
• Dockerized execution
• Event-driven scalability using select() or epoll
• Unit and integration test coverage

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Author

Smeet Patel

• GitHub: smeetpatel2530
• LinkedIn: Smeet Patel

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License

This project is open for learning and portfolio use.