ut_metadata 
BitTorrent Extension for Peers to Send Metadata Files (BEP 9)
JavaScript implementation of the Extension for Peers to Send Metadata Files (BEP 9). Use with bittorrent-protocol.
The purpose of this extension is to allow clients to join a swarm and complete a download without the need of downloading a .torrent file first. This extension instead allows clients to download the metadata from peers. It makes it possible to support magnet links, a link on a web page only containing enough information to join the swarm (the info hash).
Works in the browser with browserify! This module is used by WebTorrent.
install
npm install ut_metadata
usage
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:
const Protocol = require('bittorrent-protocol')
const net = require('net')
net.createServer(socket => {
var wire = new Protocol()
socket.pipe(wire).pipe(socket)
// handle handshake
wire.on('handshake', (infoHash, peerId) => {
wire.handshake(new Buffer('my info hash'), new Buffer('my peer id'))
})
}).listen(6881)
To add support for BEP 9, simply modify your code like this:
const Protocol = require('bittorrent-protocol')
const net = require('net')
const ut_metadata = require('ut_metadata')
net.createServer(socket => {
const wire = new Protocol()
socket.pipe(wire).pipe(socket)
// initialize the extension
wire.use(ut_metadata())
// all `ut_metadata` functionality can now be accessed at wire.ut_metadata
// ask the peer to send us metadata
wire.ut_metadata.fetch()
// 'metadata' event will fire when the metadata arrives and is verified to be correct!
wire.ut_metadata.on('metadata', metadata => {
// got metadata!
// Note: the event will not fire if the peer does not support ut_metadata, if they
// don't have metadata yet either, if they repeatedly send invalid data, or if they
// simply don't respond.
})
// optionally, listen to the 'warning' event if you want to know that metadata is
// probably not going to arrive for one of the above reasons.
wire.ut_metadata.on('warning', err => {
console.log(err.message)
})
// handle handshake
wire.on('handshake', (infoHash, peerId) => {
wire.handshake(new Buffer('my info hash'), new Buffer('my peer id'))
})
}).listen(6881)
api
ut_metadata([metadata])
Initialize the extension. If you have the torrent metadata (Buffer), pass it into the
ut_metadata constructor so it's made available to the peer.
const metadata = fs.readFileSync(__dirname + '/file.torrent')
wire.use(ut_metadata(metadata))
ut_metadata.fetch()
Ask the peer to send metadata.
ut_metadata.cancel()
Stop asking the peer to send metadata.
ut_metadata.setMetadata(metadata)
Set the metadata. If you didn't have the metadata at the time ut_metadata was
initialized, but you end up getting it from another peer (or somewhere else), you should
call setMetadata so the metadata will be available to the peer.
ut_metadata.on('metadata', function (metadata) {})
Fired when metadata is available and verified to be correct. Called with a single
parameter of type Buffer.
wire.ut_metadata.on('metadata', metadata => {
console.log(Buffer.isBuffer(metadata)) // true
})
Note: the event will not fire if the peer does not support ut_metadata, if they
don't have metadata yet either, if they repeatedly send invalid data, or if they
simply don't respond.
ut_metadata.on('warning', function (err) {})
Fired if:
- the peer does not support ut_metadata
- the peer doesn't have metadata yet
- the peer repeatedly sent invalid data
wire.ut_metadata.on('warning', err => {
console.log(err.message)
})
license
MIT. Copyright (c) Feross Aboukhadijeh and WebTorrent, LLC.