github.com/nigeltroy/bittorrent-client-go

bittorrent-client-go

A simple BitTorrent client in Go.

Motivation

I wanted to learn Go and async programming! An actual fully-featured BitTorrent client is a huge undertaking (see FOSS project qBittorrent), so this only aims to be an extremely simplified version of one.

Project progress

Components of program

• CLI
• GTK UI
• API
  • Torrent
    • URL
    • File
    • Info hash/Magnet link
  • Tracker
  • Peers
  • Client

BitTorrent protocol spec fields

Information on the following fields can be found in the BitTorrent protocol spec (or a spec change request) or in the spec in the BitTorrent Wiki. A simplified version of this program only needs to support some non-optional fields.

Metainfo

• info
  • piece length
  • pieces
  • private
  • Single file mode
    • name
    • length
    • md5sum
  • Multiple file mode
    • name
    • files
      • length
      • path
      • md5sum
• announce
• announce-list
• creation date
• comment
• created by
• encoding
• url-list ??? - I found this while trying to debug the Arch torrent, but it isn't documented in the BitTorrent spec

Trackers

• TCP announce
• UDP announce
• DHT announce
• Async announcing
• Reannouncing every <Response.interval> seconds

Request

• info_hash
• peer_id
• port
• uploaded
• downloaded
• left
• compact
• no_peer_id
• event
• ip
• numwant
• key
• trackerid

Response

• failure reason
• warning message
• interval
• min interval
• tracker id
• complete
• incomplete
• peers
  • Dictionary model
    • peer id
    • ip
    • port
  • Binary model

Peers

• Handshake