The BitTorrent lt_donthave extension (BEP 54)
npm install lt_donthave[ci-image]: https://github.com/webtorrent/lt_donthave/actions/workflows/ci.yml/badge.svg?branch=master
[ci-url]: https://github.com/webtorrent/lt_donthave/actions
[npm-image]: https://img.shields.io/npm/v/lt_donthave.svg
[npm-url]: https://npmjs.org/package/lt_donthave
[downloads-image]: https://img.shields.io/npm/dm/lt_donthave.svg
[downloads-url]: https://npmjs.org/package/lt_donthave
[standard-image]: https://img.shields.io/badge/code_style-standard-brightgreen.svg
[standard-url]: https://standardjs.com
JavaScript implementation of the The BitTorrent lt_donthave extension (BEP 54). Use with bittorrent-protocol.
The purpose of this extension is to allow peers to indicate that they no longer have a piece. It provides a single donthave message that means the opposite of the standard have message. In addition, when a client receives donthave, it knows that all requests for the matching piece have failed.
Works in the browser with browserify! This module is used by WebTorrent.
``
npm install lt_donthave
This package should be used with bittorrent-protocol, which supports a plugin-like system for extending the protocol with additional functionality.
Say you're already using bittorrent-protocol. Your code might look something like this:
`js
import BitField from 'bitfield'
import Protocol from 'bittorrent-protocol'
import net from 'net'
net.createServer(socket => {
var wire = new Protocol()
socket.pipe(wire).pipe(socket)
// handle handshake
wire.on('handshake', (infoHash, peerId) => {
wire.handshake(Buffer.from('my info hash'), Buffer.from('my peer id'))
// advertise that we have all 10 pieces of the torrent
const bitfield = new BitField(10)
for (let i = 0; i <= 10; i++) {
bitfield.set(i, true)
}
wire.bitfield(bitfield)
})
}).listen(6881)
`
To add support for BEP 54, simply modify your code like this:
`js
import BitField from 'bitfield'
import Protocol from 'bittorrent-protocol'
import net from 'net'
import lt_donthave from 'lt_donthave'
net.createServer(socket => {
const wire = new Protocol()
socket.pipe(wire).pipe(socket)
// initialize the extension
wire.use(lt_donthave())
// all lt_donthave functionality can now be accessed at wire.lt_donthave
wire.on('request', (pieceIndex, offset, length, cb) => {
// whoops, turns out we don't have any pieces after all
wire.lt_donthave.donthave(pieceIndex)
cb(new Error('not found'))
})
// 'donthave' event will fire when the remote peer indicates it no longer has a piece
wire.lt_donthave.on('donthave', index => {
// remote peer no longer has piece index
})
// handle handshake
wire.on('handshake', (infoHash, peerId) => {
wire.handshake(Buffer.from('my info hash'), Buffer.from('my peer id'))
// advertise that we have all 10 pieces of the torrent
const bitfield = new BitField(10)
for (let i = 0; i <= 10; i++) {
bitfield.set(i, true)
}
wire.bitfield(bitfield)
})
}).listen(6881)
`
#### lt_donthave()
Initialize the extension.
`js`
wire.use(lt_donthave())
#### lt_donthave.donthave(index)
Tell the remote peer that this peer no longer has the piece with the specified index.
Opposite of wire.have.
#### lt_donthave.on('donthave', index => {})
Fired when the remote peer no longer has the piece with the specified index.
Opposite of wire.on('have', index => ())`
After this is fired, all outstanding requests to the remote peer for that piece will automatically fail.
MIT. Copyright (c) John Hiesey and WebTorrent, LLC.