amish

A minimal, zero-dependency BitTorrent client written in pure Go.

Usage

go build -o amish .
./amish "magnet:?xt=urn:btih:..."

Files are saved to the current working directory.

Features

• Magnet link support -- downloads from magnet URIs (hex and base32 info hashes)
• Metadata fetching -- retrieves torrent metadata from peers via BEP 9/10 extension protocol
• DHT peer discovery -- finds peers via the distributed hash table (BEP 5)
• HTTP & UDP trackers -- announces to both tracker types
• Endgame mode -- races peers for the last pieces to avoid tail latency
• Multi-file torrents -- handles torrents with multiple files and nested directories
• Pipelined downloads -- requests up to 16 blocks per peer concurrently
• Piece verification -- SHA1 hash check on every downloaded piece
• Progress display -- terminal progress bar with download speed

Architecture

main.go          Entry point, two-phase download (metadata then pieces)
torrent/         Download orchestration, piece management, endgame, file writing
peer/            BitTorrent wire protocol, handshake, message serialization
tracker/         HTTP and UDP tracker announce
dht/             DHT client for trackerless peer discovery
magnet/          Magnet URI parsing
metainfo/        Torrent metadata (info dict) parsing
bencode/         Bencode encoding/decoding
display/         Terminal progress bar

Testing

go test ./...

License

MIT