[CLOSED] TypeError: Cannot read property 'byteLength' of undefined

[feross]

Issue by iamale
Thursday Apr 24, 2014 at 17:24 GMT
Originally opened as https://github.com/feross/bittorrent-client/issues/2

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Seems like quite an issue for me. Code:

#!/usr/bin/env node

var BitTorrentClient = require('bittorrent-client');

var client = BitTorrentClient();
var magnet = "magnet:?xt=urn:btih:1e69917fbaa2c767bca463a96b5572785c6d8a12";
client.add(magnet);
// client.on("torrent", ...);

Output:

[lots of peer-connected-lines, like]
82.xx.xx.105:34xxx supports DHT
Connecting to 187.xx.xx.88:10xxx
Connecting to 71.xx.xx.176:10xxx
Connecting to 189.xx.xx.172:56xxx
86.xx.xx.176:29xxx supports DHT

/home/ale/sandbox/node_modules/bittorrent-client/node_modules/rusha-browserify/rusha.js:150
      var len = str.byteLength || str.length;
                   ^
TypeError: Cannot read property 'byteLength' of undefined
    at Rusha.rawDigest.rawDigest (/home/ale/sandbox/node_modules/bittorrent-client/node_modules/rusha-browserify/rusha.js:150:20)
    at Rusha.digest.digestFromString.digestFromBuffer.digestFromArrayBuffer (/home/ale/sandbox/node_modules/bittorrent-client/node_modules/rusha-browserify/rusha.js:174:18)
    at sha1 (/home/ale/sandbox/node_modules/bittorrent-client/node_modules/ut_metadata/index.js:11:24)
    at ut_metadata._checkDone (/home/ale/sandbox/node_modules/bittorrent-client/node_modules/ut_metadata/index.js:186:9)
    at ut_metadata._onData (/home/ale/sandbox/node_modules/bittorrent-client/node_modules/ut_metadata/index.js:147:10)
    at ut_metadata.onMessage (/home/ale/sandbox/node_modules/bittorrent-client/node_modules/ut_metadata/index.js:80:14)
    at Wire._onExtended (/home/ale/sandbox/node_modules/bittorrent-client/node_modules/bittorrent-swarm/node_modules/bittorrent-protocol/index.js:438:24)
    at Wire._onmessage (/home/ale/sandbox/node_modules/bittorrent-client/node_modules/bittorrent-swarm/node_modules/bittorrent-protocol/index.js:582:19)
    at Wire._write (/home/ale/sandbox/node_modules/bittorrent-client/node_modules/bittorrent-swarm/node_modules/bittorrent-protocol/index.js:481:10)
    at doWrite (_stream_writable.js:219:10)

You're getting a similar error on Travis, too. And you might have noticed the problem before, but I'm posting it just in case.

[feross]

Comment by feross
Friday May 02, 2014 at 16:51 GMT

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Thanks for the report. Will fix.

[feross]

Comment by fisch0920
Tuesday May 06, 2014 at 07:00 GMT

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I've really interested in this project and you've done a great job so far! I started a deep-dive of the bittorrent-* libs mainly to familiarize myself with everything but with this immediate bug in mind. To that end, I've found a few related issues.

• ut_metadata only deals with the info-dictionary part of the .torrent file, and in ut_metadata._checkDone, the line

info = bncode.encode(bncode.decode(this.metadata).info)

should be changed to:

info = bncode.encode(bncode.decode(this.metadata))

which is almost a noop except for validating that the metadata is valid bncoded.

Then, the metadata that ut_metadata emits to listeners should be in the form { info : this.metadata }.

The problem then comes in parsing the torrent's metadata where the following line fails because we just have the metadata info dictionary and not the whole .torrent file.
ensure(torrent['announce-list'] || torrent.announce, 'announce-list/announce')

I'm not nearly as familiar with the ins & outs of the protocols, but these areas seem to have contradicting assumptions.

The other issue I ran into deals with the ordering of the onHandshake/onWire logic. Specifically, ut_metadata.onHandshake should be called before ut_metadata._checkDone, because _checkDone relies on having an infohash set, but in reality ut_metadata.onHandshake is never called. This appears to be because Wire._onHandshake (bittorrent-protocol) emits the handshake event after calling the extensions onHandshake, but in this case the handshake event that is emitted from Wire trickles up the stack to Swarm._onwire and Torrent._onWire, which is where the ut_metadata is initialized on the wire via

wire.use(ut_metadata(self.metadata))

If I rearrange the emit to happen before calling the registered extension handshakes (allowing the torrent to register ut_metadata on the wire), this problem is resolved. That being said, the control flow for handshakes is confusing, so there may be a better solution to this problem.

e.g. change:

Wire.prototype._onHandshake = function (infoHash, peerId, extensions) {
  this.peerId = peerId
  this.peerExtensions = extensions

  for (var name in this._ext) {
    this._ext[name].onHandshake(infoHash, peerId, extensions)
  }
  this.emit('handshake', infoHash, peerId, extensions)

to

Wire.prototype._onHandshake = function (infoHash, peerId, extensions) {
  this.peerId = peerId
  this.peerExtensions = extensions

  this.emit('handshake', infoHash, peerId, extensions)
  for (var name in this._ext) {
    this._ext[name].onHandshake(infoHash, peerId, extensions)
  }

[feross]

Comment by feross
Wednesday May 07, 2014 at 19:57 GMT

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@fisch0920 You're right on all counts. Thanks for all the PRs! They've all been merged 👍

[feross]

Comment by iamale
Thursday May 08, 2014 at 02:21 GMT

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👍 Thanks guys, you're awesome!