This repository implements BitTorrent-related packages and command-line utilities in Go. The emphasis is on use as a library from other projects. It's been used 24/7 in production by downstream services since late 2014. The implementation was specifically created to explore Go's concurrency capabilities, and to include the ability to stream data directly from the BitTorrent network. To this end it supports seeking, readaheads and other features exposing torrents and their files with the various Go idiomatic io package interfaces. This is also demonstrated through torrentfs.

There is support for protocol encryption, DHT, PEX, uTP, and various extensions. There are several data storage backends provided: blob, file, bolt, and mmap, to name a few. You can write your own to store data for example on S3, or in a database.

Some noteworthy package dependencies that can be used for other purposes include:

• go-libutp
• dht
• bencode
• tracker

Install the library package with go get github.com/anacrolix/torrent, or the provided cmds with go get github.com/anacrolix/torrent/cmd/....

There are some small examples in the package documentation.

There are several web-frontends and Android clients among the known public projects:

• Torrent.Express
• Confluence
• Trickl
• Elementum
• goTorrent
• Go Peerflix
• Cloud Torrent
• Android Torrent Client
• libtorrent
• Remote-Torrent

Communication about the project is primarily through Gitter and the issue tracker.

Here I'll describe what some of the packages in ./cmd do.

Note that the godo command which is invoked in the following examples builds and executes a Go import path, like go run. It's easier to use this convention than to spell out the install/invoke cycle for every single example.

Downloads torrents from the command-line. This first example does not use godo.

$ go get github.com/anacrolix/torrent/cmd/torrent
# Now 'torrent' should be in $GOPATH/bin, which should be in $PATH.
$ torrent 'magnet:?xt=urn:btih:KRWPCX3SJUM4IMM4YF5RPHL6ANPYTQPU'
ubuntu-14.04.2-desktop-amd64.iso [===================================================================>]  99% downloading (1.0 GB/1.0 GB)
2015/04/01 02:08:20 main.go:137: downloaded ALL the torrents
$ md5sum ubuntu-14.04.2-desktop-amd64.iso
1b305d585b1918f297164add46784116  ubuntu-14.04.2-desktop-amd64.iso
$ echo such amaze
wow

torrentfs mounts a FUSE filesystem at -mountDir. The contents are the torrents described by the torrent files and magnet links at -metainfoDir. Data for read requests is fetched only as required from the torrent network, and stored at -downloadDir.

$ mkdir mnt torrents
$ godo github.com/anacrolix/torrent/cmd/torrentfs -mountDir=mnt -metainfoDir=torrents &
$ cd torrents
$ wget http://releases.ubuntu.com/14.04.2/ubuntu-14.04.2-desktop-amd64.iso.torrent
$ cd ..
$ ls mnt
ubuntu-14.04.2-desktop-amd64.iso
$ pv mnt/ubuntu-14.04.2-desktop-amd64.iso | md5sum
996MB 0:04:40 [3.55MB/s] [========================================>] 100%
1b305d585b1918f297164add46784116  -

Creates a magnet link from a torrent file. Note the extracted trackers, display name, and info hash.

$ godo github.com/anacrolix/torrent/cmd/torrent-magnet < ubuntu-14.04.2-desktop-amd64.iso.torrent
magnet:?xt=urn:btih:546cf15f724d19c4319cc17b179d7e035f89c1f4&dn=ubuntu-14.04.2-desktop-amd64.iso&tr=http%3A%2F%2Ftorrent.ubuntu.com%3A6969%2Fannounce&tr=http%3A%2F%2Fipv6.torrent.ubuntu.com%3A6969%2Fannounce