Scrape implementation for websocket. Issue webtorrent#116

Author: yciabaud

lib/client/websocket-tracker.js

@@ -47,6 +47,7 @@ WebSocketTracker.prototype.announce = function (opts) {
 
   self._generateOffers(numwant, function (offers) {
     var params = extend(opts, {
+      action: 'announce',
       numwant: numwant,
       info_hash: self.client._infoHashBinary,
       peer_id: self.client._peerIdBinary,
@@ -61,7 +62,21 @@ WebSocketTracker.prototype.announce = function (opts) {
 WebSocketTracker.prototype.scrape = function (opts) {
   var self = this
   if (self.destroyed || self.reconnecting) return
-  self._onSocketError(new Error('scrape not supported ' + self.announceUrl))
+  if (!self.socket.connected) {
+    return self.socket.once('connect', self.scrape.bind(self, opts))
+  }
+
+  var infoHashes = (Array.isArray(opts.infoHash) && opts.infoHash.length > 0)
+    ? opts.infoHash.map(function (infoHash) {
+      return infoHash.toString('binary')
+    })
+    : (opts.infoHash && opts.infoHash.toString('binary')) || self.client._infoHashBinary
+  var params = {
+    action: 'scrape',
+    info_hash: infoHashes
+  }
+
+  self._send(params)
 }
 
 WebSocketTracker.prototype.destroy = function (onclose) {
@@ -133,6 +148,18 @@ WebSocketTracker.prototype._onSocketData = function (data) {
     return
   }
 
+  if (data.action === common.ACTIONS.ANNOUNCE || data.offer || data.answer) {
+    self._onAnnounceResponse(data)
+  } else if (data.action === common.ACTIONS.SCRAPE) {
+    self._onScrapeResponse(data)
+  } else {
+    throw new Error('invalid action in WS response: ' + data.action)
+  }
+}
+
+WebSocketTracker.prototype._onAnnounceResponse = function (data) {
+  var self = this
+
   if (data.info_hash !== self.client._infoHashBinary) {
     debug(
       'ignoring websocket data from %s for %s (looking for %s: reused socket)',
@@ -215,6 +242,32 @@ WebSocketTracker.prototype._onSocketData = function (data) {
   }
 }
 
+WebSocketTracker.prototype._onScrapeResponse = function (data) {
+  var self = this
+  // NOTE: the unofficial spec says to use the 'files' key, 'host' has been
+  // seen in practice
+  data = data.files || data.host || {}
+
+  var keys = Object.keys(data)
+  if (keys.length === 0) {
+    self.client.emit('warning', new Error('invalid scrape response'))
+    return
+  }
+
+  keys.forEach(function (infoHash) {
+    var response = data[infoHash]
+    // TODO: optionally handle data.flags.min_request_interval
+    // (separate from announce interval)
+    self.client.emit('scrape', {
+      announce: self.announceUrl,
+      infoHash: common.binaryToHex(infoHash),
+      complete: response.complete,
+      incomplete: response.incomplete,
+      downloaded: response.downloaded
+    })
+  })
+}
+
 WebSocketTracker.prototype._onSocketClose = function () {
   var self = this
   if (self.destroyed) return

lib/server/parse-websocket.js

@@ -6,33 +6,51 @@ function parseWebSocketRequest (socket, opts, params) {
   if (!opts) opts = {}
   params = JSON.parse(params) // may throw
 
-  params.action = common.ACTIONS.ANNOUNCE
   params.type = 'ws'
   params.socket = socket
+  if (params.action === 'announce' || params.answer || params.offers) {
+    params.action = common.ACTIONS.ANNOUNCE
 
-  if (typeof params.info_hash !== 'string' || params.info_hash.length !== 20) {
-    throw new Error('invalid info_hash')
-  }
-  params.info_hash = common.binaryToHex(params.info_hash)
+    if (typeof params.info_hash !== 'string' || params.info_hash.length !== 20) {
+      throw new Error('invalid info_hash')
+    }
+    params.info_hash = common.binaryToHex(params.info_hash)
 
-  if (typeof params.peer_id !== 'string' || params.peer_id.length !== 20) {
-    throw new Error('invalid peer_id')
-  }
-  params.peer_id = common.binaryToHex(params.peer_id)
+    if (typeof params.peer_id !== 'string' || params.peer_id.length !== 20) {
+      throw new Error('invalid peer_id')
+    }
+    params.peer_id = common.binaryToHex(params.peer_id)
 
-  if (params.answer) {
-    if (typeof params.to_peer_id !== 'string' || params.to_peer_id.length !== 20) {
-      throw new Error('invalid `to_peer_id` (required with `answer`)')
+    if (params.answer) {
+      if (typeof params.to_peer_id !== 'string' || params.to_peer_id.length !== 20) {
+        throw new Error('invalid `to_peer_id` (required with `answer`)')
+      }
+      params.to_peer_id = common.binaryToHex(params.to_peer_id)
     }
-    params.to_peer_id = common.binaryToHex(params.to_peer_id)
-  }
 
-  params.left = Number(params.left) || Infinity
-  params.numwant = Math.min(
-    Number(params.offers && params.offers.length) || 0, // no default - explicit only
-    common.MAX_ANNOUNCE_PEERS
-  )
-  params.compact = -1 // return full peer objects (used for websocket responses)
+    params.left = Number(params.left) || Infinity
+    params.numwant = Math.min(
+      Number(params.offers && params.offers.length) || 0, // no default - explicit only
+      common.MAX_ANNOUNCE_PEERS
+    )
+    params.compact = -1 // return full peer objects (used for websocket responses)
+  } else if (params.action === 'scrape') {
+    params.action = common.ACTIONS.SCRAPE
+
+    if (typeof params.info_hash === 'string') params.info_hash = [ params.info_hash ]
+    if (Array.isArray(params.info_hash)) {
+      params.info_hash = params.info_hash.map(function (binaryInfoHash) {
+        if (typeof binaryInfoHash !== 'string' || binaryInfoHash.length !== 20) {
+          throw new Error('invalid info_hash')
+        }
+        return common.binaryToHex(binaryInfoHash)
+      })
+    } else {
+      params.info_hash = common.binaryToHex(params.info_hash)
+    }
+  } else {
+    throw new Error('invalid action in WS request: ' + params.action)
+  }
 
   params.ip = opts.trustProxy
       ? socket.upgradeReq.headers['x-forwarded-for'] || socket.upgradeReq.connection.remoteAddress

server.js

@@ -327,6 +327,7 @@ Server.prototype._onWebSocketRequest = function (socket, opts, params) {
   self._onRequest(params, function (err, response) {
     if (err) {
       socket.send(JSON.stringify({
+        action: params.action,
         'failure reason': err.message,
         info_hash: common.hexToBinary(params.info_hash)
       }), socket.onSend)
@@ -336,9 +337,14 @@ Server.prototype._onWebSocketRequest = function (socket, opts, params) {
     }
     if (self.destroyed) return
 
-    if (socket.infoHashes.indexOf(params.info_hash) === -1) {
-      socket.infoHashes.push(params.info_hash)
-    }
+    var hashes
+    if (typeof params.info_hash === 'string') hashes = [ params.info_hash ]
+    else hashes = params.info_hash
+    hashes.forEach(function (info_hash) {
+      if (socket.infoHashes.indexOf(info_hash) === -1) {
+        socket.infoHashes.push(info_hash)
+      }
+    })
 
     var peers = response.peers
     delete response.peers