go-torrent

go-torrent is a Go-based BitTorrent client that began as a Codecrafters challenge but has since evolved into a more extensive project, designed with a future-proof architecture to incorporate additional BitTorrent Enhancement Proposals (BEPs). This repository demonstrates not only my implementation of core BitTorrent protocol components but also a custom-built bencode serializer/deserializer, allowing for precise control over torrent data encoding.

Features

• Bencode Serializer/Deserializer: Built from scratch, the bencode package offers encoding and decoding of torrent files and peer communication. It supports all core bencode types, including integers, strings, lists, and dictionaries.
• Torrent Tracker Interaction: Communicates with torrent trackers via GET requests, querying with precise parameters like info_hash, peer_id, and port to receive peer data.
• Peer Message Handling: Full implementation of message types such as choke, unchoke, and piece requests, with validation to ensure data integrity and seamless peer interactions.
• Piece Downloading with Integrity Checks: Includes hashing to validate downloaded pieces, preventing corrupted data from impacting the download.
• Concurrent Block Downloading: Implements pipelined downloading to optimize download speed, using multiple goroutines to fetch blocks concurrently.
• Error Recovery: Incorporates retry mechanisms and re-queuing for blocks that fail, ensuring robustness in varying network conditions.

Roadmap

This project is built with a modular approach to support future BEPs and additional protocol features. Planned enhancements include:

1. Peer Exchange (PEX): Enhance peer discovery by exchanging peer lists with connected clients, reducing reliance on central trackers.
2. DHT (Distributed Hash Table): Add support for a decentralized peer lookup system, making downloads more resilient.
3. Magnet Link Support: Implement magnet URI parsing for direct, trackerless torrent loading.

Code Structure

The codebase is divided into clear, modular packages, making it easy to navigate and extend:

• cmd/ - Contains CLI-related code, allowing users to initiate torrent downloads via command line.
• internal/torrent/ - Core torrent logic, including piece management, peer connection handling, and download coordination.
• internal/bencode/ - Custom bencode serializer and deserializer.
• tests/ - Comprehensive unit tests for each protocol component to ensure stability and accuracy.

Getting Started

Clone the repository and build the CLI application:

git clone https://github.com/maxolivera/go-torrent.git
cd go-torrent
go build -o go-torrent ./cmd/

Example Usage

To download a torrent file:

./go-torrent download <path-to-torrent-file>

Testing

Run the unit tests to verify functionality:

go test ./...

Learnings and Future Goals

Through this project, I've deepened my understanding of network protocols, binary data handling, and concurrency in Go. My goal is to continue developing go-torrent into a robust, feature-complete BitTorrent client, showcasing not only my software development skills but also my enthusiasm for distributed systems.

Contributing

If you'd like to contribute, please fork the repository and open a pull request to the master branch.