BitTorrent

A simple BitTorrent client written in C++.

This project demonstrates how BitTorrent works internally by implementing the core parts of the protocol:

• Reading .torrent files
• Communicating with trackers
• Discovering peers
• Performing peer handshakes
• Downloading files piece-by-piece

This is not a production-ready torrent client. It is intended for learning, experimentation, and understanding distributed file sharing.

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Features

• Parse .torrent files
• Contact HTTP trackers
• Discover peers
• Perform BitTorrent handshakes
• Download single-file torrents
• Works on Linux, macOS, and Windows (via WSL)

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Requirements (Handled Automatically)

You do not need to manually install compilers or libraries.

The provided setup scripts automatically install everything required:

• C++ compiler
• CMake
• libcurl
• OpenSSL

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Project Structure (For Reference Only)

You do not need to modify these files to use the project.

BitTorrent/
├── src/                # C++ source code
├── include/            # Header files
├── build/              # Build output (created automatically)
├── sample.torrent      # Example torrent file
├── setup.sh            # Setup script for Linux/macOS
├── setup.ps1           # Setup script for Windows (WSL)
├── CMakeLists.txt
└── README.md

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Quick Start (Recommended)

Linux / macOS

1. Open a terminal
2. Navigate into the project directory
3. Run:

chmod +x setup.sh
./setup.sh

This will:

• Install required dependencies
• Build the project

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Windows (via WSL – Recommended)

This project relies on Linux libraries. On Windows, it runs inside WSL (Windows Subsystem for Linux) automatically.

1. Open PowerShell
2. Navigate into the project directory
3. Run:

.\setup.ps1

If WSL is not installed, the script will clearly tell you how to install it.

The setup script will:

• Install required dependencies
• Build the project

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Using the Program (After Setup)

After setup, the compiled executable is located at:

build/bt_main

View torrent information

./build/bt_main info sample.torrent

Displays:

• File name
• File size
• Piece length
• Number of pieces
• Tracker URL

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Get peers from the tracker

./build/bt_main peers sample.torrent

Displays a list of peers (ip:port) currently sharing the file.

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Perform a handshake with a peer

./build/bt_main handshake sample.torrent <ip:port>

Example:

./build/bt_main handshake sample.torrent 165.232.35.114:51443

This confirms successful communication with a peer.

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Download the full file

./build/bt_main download -o out.bin sample.torrent

• Downloads the full file described by the torrent
• Saves it as out.bin
• Pieces are downloaded sequentially

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Notes for Non-Technical Users

• This is a command-line application
• There is no graphical interface
• Download speed may be slower than popular torrent clients
• Only single-file torrents are supported
• This project is meant for learning and experimentation

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License

This project is provided for educational purposes only. Use responsibly.