Parse torrent file from XMLHttpRequest

[jakefb]

I want to stream a video in the browser from a .torrent file. To do this I have made an XHR request to return a buffer, which I want to parse with parse-torrent and download with WebTorrent. This is because I want to load the whole torrent file, so I can start streaming for a HTTP WebSeed, without having to wait for WebRTC peers to connect.

I don't know how to do this so help would be greatly appreciated. Here's my code:

function reqListener () {
  console.log('.torrent file download')

  var videoTorrent =  new Uint8Array(this.response)
  var parsedTorrent =  parseTorrent(videoTorrent)
  client.add(parsedTorrent, onTorrent)
}

var oReq = new XMLHttpRequest()

oReq.addEventListener("load", reqListener)

oReq.responseType = 'arraybuffer';

oReq.open('GET', '/torrents/yosemite-hd.torrent', true)

oReq.send()

function onTorrent (torrent) {
  ...
}

[jakefb]

I managed to get this working by using stream-http - thanks @jhiesey. You can see it in action here http://fastcast.nz/videos/cityscape-chicago-ii.html. Here's some of the code from my project (source)

var parseTorrent = require('parse-torrent')
var http = require('stream-http')
var WebTorrent = require('webtorrent')

var torrentName = 'cityscape-chicago-ii.torrent'

http.get('/torrents/' + torrentName, function (res) {
  var data = [] // List of Buffer objects

  res.on("data", function(chunk) {
    data.push(chunk) // Append Buffer object
  })

  res.on("end", function() {
    data = Buffer.concat(data) // Make one large Buffer of it

    var torrentParsed = parseTorrent(data) // Parse the Buffer

    var client = new WebTorrent()

    client.add(torrentParsed, onTorrent)

    function onTorrent (torrent) {
      ...
    }
  })
})

[vintikzzz]

It could be achieved without additional dependencies. The main idea is to convert from ArrayBuffer to Buffer.
This works!

            const xhr = new XMLHttpRequest();
            xhr.onreadystatechange = function() {
              if (this.readyState == 4) {
                const ab = new Uint8Array(this.response);
                const buffer = new Buffer(ab.byteLength);
                const view = new Uint8Array(ab);
                for (let i = 0; i < buffer.length; ++i) {
                  buffer[i] = view[i];
                }
                const torrent = parseTorrent(buffer);
              }
            };
            xhr.open('GET', 'http://exmaple-url');
            xhr.responseType = 'arraybuffer';
            xhr.send();

[SilentBot1]

Hey @vintikzzz, since the original post, the WebTorrent library (parse-torrent) added support for passing through a URL to a .torrent file while calling client.add().

An example of this in action:

var WebTorrent = require('webtorrent')
var client = new WebTorrent()

var torrent = client.add("https://webtorrent.io/torrents/sintel.torrent")

Note: In a browser the URL must have the header 'Access-Control-Allow-Origin' set while in Node.js, it doesn't mind.

[jakefb]

Thanks @vintikzzz and @SilentBot1 😃

Good to know that this is supported in parse-torrent