BEP46 — Mutable Torrents

.travis.yml

@@ -10,3 +10,11 @@ env:
   global:
     - secure: lLh4WEpXrERVSJlpDLA0PQ+wRG4ascs3oydkiGV3VQ0G5vTrsTzrCGy3ZTt9q9L28ThKGt5n9VIKOVFahNEM9AWuim/9scXo+bCMttlWctAudw/jtxhr1vZqPw+lb+ZVsWaexv+OgoVwzY12eVP+jh1iGr7M1PcmDh8ardDyGQ0=
     - secure: DP949nTUjP1b92+Xq9JfWgaoVU7GWcWhLo6zuQpTv5Y06N6/677Z926SghysdA/OO8OYtHemPIc096oYIBKzK0Lhe772l7f/Lse81gJ78ggWaFrOGZWZ32KapWqVuOxn4OPXn8tBRPrvNN4ApB3I8gY/mfGkPfRnmOIfA2nDZrU=
+  matrix:
+    - CXX=g++-4.8
+addons:
+  apt:
+    sources:
+      - ubuntu-toolchain-r-test
+    packages:
+      - g++-4.8

index.js

@@ -8,6 +8,7 @@ var fs = require('fs') // browser exclude
 var get = require('simple-get')
 var magnet = require('magnet-uri')
 var parseTorrentFile = require('parse-torrent-file')
+var crypto = require('crypto')
 
 module.exports.toMagnetURI = magnet.encode
 module.exports.toTorrentFile = parseTorrentFile.encode
@@ -20,7 +21,9 @@ module.exports.toTorrentFile = parseTorrentFile.encode
 function parseTorrent (torrentId) {
   if (typeof torrentId === 'string' && /^(stream-)?magnet:/.test(torrentId)) {
     // magnet uri (string)
-    return magnet(torrentId)
+    var m = magnet(torrentId)
+    if (m.xs) throw new Error('Exact source magnets need to call .remote()')
+    return m
   } else if (typeof torrentId === 'string' && (/^[a-f0-9]{40}$/i.test(torrentId) || /^[a-z2-7]{32}$/i.test(torrentId))) {
     // info hash (hex/base-32 string)
     return magnet('magnet:?xt=urn:btih:' + torrentId)
@@ -43,7 +46,8 @@ function parseTorrent (torrentId) {
   }
 }
 
-function parseTorrentRemote (torrentId, cb) {
+function parseTorrentRemote (opts, cb) {
+  var torrentId = (typeof opts === 'object' && !isBlob(opts)) ? opts.torrentId : opts
   var parsedTorrent
   if (typeof cb !== 'function') throw new Error('second argument must be a Function')
 
@@ -63,6 +67,29 @@ function parseTorrentRemote (torrentId, cb) {
       if (err) return cb(new Error('Error converting Blob: ' + err.message))
       parseOrThrow(torrentBuf)
     })
+  } else if (opts.dht && /^(stream-)?magnet:/.test(torrentId)) {
+    var m = magnet(torrentId)
+    if (!m.xs) {
+      process.nextTick(function () {
+        cb(new Error('Missing xs (exact source) in magnet URI'))
+      })
+    } else {
+      if ((m = m.xs.match(/^urn:btpk:(.{64})/))) {
+        var publicKey = m[1].toLowerCase()
+        var publicKeyBuf = Buffer.from(publicKey, 'hex')
+        var targetId = crypto.createHash('sha1').update(publicKeyBuf).digest('hex') // XXX missing salt
+
+        opts.dht.get(targetId, function (err, res) {
+          if (err) return cb(new Error('Error finding this publicKey in the DHT'))
+          if (res.v && !res.v.ih) return cb(new Error('Found publicKey in DHT, but no torrent inside'))
+          parseOrThrow(res.v.ih)
+        })
+      } else {
+        process.nextTick(function () {
+          cb(new Error('Can\'t find publicKey in magnet URI'))
+        })
+      }
+    }
   } else if (typeof get === 'function' && /^https?:/.test(torrentId)) {
     // http, or https url to torrent file
     get.concat({

package.json

@@ -20,7 +20,9 @@
   },
   "devDependencies": {
     "airtap": "0.0.4",
+    "bittorrent-dht": "^7.3.1",
     "brfs": "^1.0.0",
+    "ed25519-supercop": "^1.0.2",
     "standard": "*",
     "tape": "^4.0.0",
     "webtorrent-fixtures": "^1.0.0",

test/basic-node.js

@@ -1,6 +1,9 @@
 var fixtures = require('webtorrent-fixtures')
 var http = require('http')
+var DHT = require('bittorrent-dht')
+var ed = require('ed25519-supercop')
 var parseTorrent = require('../')
+var crypto = require('crypto')
 var test = require('tape')
 
 test('http url to a torrent file, string', function (t) {
@@ -30,3 +33,73 @@ test('filesystem path to a torrent file, string', function (t) {
     t.deepEqual(parsedTorrent, fixtures.leaves.parsedTorrent)
   })
 })
+
+test('dht put/get of torrent (BEP46)', function (t) {
+  t.plan(6)
+
+  var infoHashBuf = Buffer.from(fixtures.numbers.parsedTorrent.infoHash, 'hex')
+  t.equal(infoHashBuf.length, 20, 'infoHashBuf is 20 bytes')
+
+  var keypair = ed.createKeyPair(ed.createSeed())
+
+  var dht = new DHT({ bootstrap: false, verify: ed.verify })
+  t.once('end', function () {
+    dht.destroy()
+  })
+
+  dht.on('warning', function (err) { t.fail(err) })
+  dht.on('error', function (err) { t.fail(err) })
+
+  dht.on('ready', function () {
+    var opts = {
+      k: keypair.publicKey,
+      sign: function (buf) {
+        return ed.sign(buf, keypair.publicKey, keypair.secretKey)
+      },
+      seq: 0,
+      v: {
+        ih: infoHashBuf
+      }
+    }
+
+    var expectedHash = crypto.createHash('sha1').update(opts.k).digest()
+
+    dht.put(opts, function (_, hash) {
+      t.equal(
+        hash.toString('hex'),
+        expectedHash.toString('hex'),
+        'hash of the public key'
+      )
+
+      // should perform a dht.get
+      parseTorrent.remote({
+        torrentId: 'magnet:?xs=urn:btpk:' + keypair.publicKey.toString('hex'),
+        dht: dht
+      }, function (err, parsedTorrent) {
+        t.ifError(err)
+        t.equal(infoHashBuf.toString('hex'), parsedTorrent.infoHash,
+          'got back what we put in'
+        )
+
+        // put a value without infohash (should throw)
+        opts.v = 'foo'
+        opts.seq++
+        dht.put(opts, function (_, hash) {
+          t.equal(
+            hash.toString('hex'),
+            expectedHash.toString('hex'),
+            'hash of the public key'
+          )
+
+          parseTorrent.remote({
+            torrentId: 'magnet:?xs=urn:btpk:' + keypair.publicKey.toString('hex'),
+            dht: dht
+          }, function (err, parsedTorrent) {
+            if (err) t.pass(err)
+            else t.fail('should have errored')
+          })
+        })
+      })
+    })
+  })
+})

test/basic.js

@@ -111,6 +111,13 @@ test('torrent file missing `name` field throws', function (t) {
   t.end()
 })
 
+test('parsing `xs` should happen with .remote()', function (t) {
+  t.throws(function () {
+    parseTorrent('magnet:?xs=urn:btpk:8543d3e6115f0f98c944077a4493dcd543e49c739fd998550a1f614ab36ed63e')
+  })
+  t.end()
+})
+
 test('parse url-list for webseed support', function (t) {
   var torrent = parseTorrent(fixtures.bunny.torrent)
   t.deepEqual(torrent.urlList, [ 'http://distribution.bbb3d.renderfarming.net/video/mp4/bbb_sunflower_1080p_30fps_stereo_abl.mp4' ])