Issue 4586, 5207 - Move the injected wrappers into a separate file

inject.preload.js

+/*
+ * This file is part of Adblock Plus <https://adblockplus.org/>,
+ * Copyright (C) 2006-2017 eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+"use strict";
+
+let randomEventName = "abp-request-" + Math.random().toString(36).substr(2);
+
+// Proxy "should we block?" messages from checkRequest inside the injected
+// code to the background page and back again.
+document.addEventListener(randomEventName, event =>
+{
+  let {url, requestType} = event.detail;
+
+  ext.backgroundPage.sendMessage({
+    type: "request.blockedByWrapper",
+    requestType,
+    url
+  }, block =>
+  {
+    document.dispatchEvent(new CustomEvent(
+      randomEventName + "-" + requestType + "-" + url, {detail: block}
+    ));
+  });
+});
+
+let injected = function(eventName)
+{
+  /*
+   * Shadow root getter wrapper

[kzar, 2017/05/12 12:06:24]

I improved this comment.

+   *
+   * After creating our shadowRoot we must wrap the getter to prevent the
+   * website from accessing it (#4191, #4298). This is required as a
+   * workaround for the lack of user style support in Chrome.
+   * See https://bugs.chromium.org/p/chromium/issues/detail?id=632009&desc=2
+   */
+  if ("shadowRoot" in Element.prototype)

[kzar, 2017/05/12 12:06:24]

I changed this logic, previously we returned if Element.prototype.shadowRoot
didn't exist, but that won't work now that the injected code is all in one large
function.

+  {
+    let ourShadowRoot = document.documentElement.shadowRoot;
+    if (ourShadowRoot)
+    {
+      let desc = Object.getOwnPropertyDescriptor(Element.prototype,
+                                                 "shadowRoot");
+      let shadowRoot = Function.prototype.call.bind(desc.get);
+
+      Object.defineProperty(Element.prototype, "shadowRoot", {
+        configurable: true, enumerable: true, get()
+        {
+          let thisShadow = shadowRoot(this);
+          return thisShadow == ourShadowRoot ? null : thisShadow;
+        }
+      });
+    }
+  }
+
+  /*

[kzar, 2017/05/12 12:06:24]

I added this comment.

+   * Shared request checking code, used by both the WebSocket and
+   * RTCPeerConnection wrappers.
+   */
+  let RealCustomEvent = window.CustomEvent;
+  let addEventListener = document.addEventListener.bind(document);
+  let removeEventListener = document.removeEventListener.bind(document);
+  let dispatchEvent = document.dispatchEvent.bind(document);
+
+  function checkRequest(requestType, url, callback)
+  {
+    let incomingEventName = eventName + "-" + requestType + "-" + url;
+
+    function listener(event)
+    {
+      callback(event.detail);
+      removeEventListener(incomingEventName, listener);
+    }
+    addEventListener(incomingEventName, listener);
+
+    dispatchEvent(new RealCustomEvent(eventName, {detail: {url, requestType}}));
+  }
+
+  // Only to be called before the page's code, not hardened.
+  function copyProperties(src, dest, properties)
+  {
+    for (let name of properties)
+    {
+      Object.defineProperty(dest, name,
+                            Object.getOwnPropertyDescriptor(src, name));
+    }
+  }
+
+  /*
+   * WebSocket wrapper
+   *
+   * Required before Chrome 58, since the webRequest API didn't allow us to
+   * intercept WebSockets.
+   * See https://bugs.chromium.org/p/chromium/issues/detail?id=129353
+   */
+  let RealWebSocket = WebSocket;
+  let closeWebSocket = Function.prototype.call.bind(
+    RealWebSocket.prototype.close
+  );
+
+  function WrappedWebSocket(url, ...args)
+  {
+    // Throw correct exceptions if the constructor is used improperly.
+    if (!(this instanceof WrappedWebSocket)) return RealWebSocket();
+    if (arguments.length < 1) return new RealWebSocket();
+
+    let websocket = new RealWebSocket(url, ...args);
+
+    checkRequest("WEBSOCKET", websocket.url, blocked =>
+    {
+      if (blocked)
+        closeWebSocket(websocket);
+    });
+
+    return websocket;
+  }
+  WrappedWebSocket.prototype = RealWebSocket.prototype;
+  window.WebSocket = WrappedWebSocket.bind();
+  copyProperties(RealWebSocket, WebSocket,
+                 ["CONNECTING", "OPEN", "CLOSING", "CLOSED", "prototype"]);
+  RealWebSocket.prototype.constructor = WebSocket;
+
+  /*
+   * RTCPeerConnection wrapper
+   *
+   * The webRequest API in Chrome does not yet allow the blocking of
+   * WebRTC connections.
+   * See https://bugs.chromium.org/p/chromium/issues/detail?id=707683
+   */
+  let RealRTCPeerConnection = window.RTCPeerConnection ||
+                                window.webkitRTCPeerConnection;
+  let closeRTCPeerConnection = Function.prototype.call.bind(
+    RealRTCPeerConnection.prototype.close
+  );
+  let RealArray = Array;
+  let RealString = String;
+  let {create: createObject, defineProperty} = Object;
+
+  function normalizeUrl(url)
+  {
+    if (typeof url != "undefined")
+      return RealString(url);
+  }
+
+  function safeCopyArray(originalArray, transform)
+  {
+    if (originalArray == null || typeof originalArray != "object")
+      return originalArray;
+
+    let safeArray = RealArray(originalArray.length);
+    for (let i = 0; i < safeArray.length; i++)
+    {
+      defineProperty(safeArray, i, {
+        configurable: false, enumerable: false, writable: false,
+        value: transform(originalArray[i])
+      });
+    }
+    defineProperty(safeArray, "length", {
+      configurable: false, enumerable: false, writable: false,
+      value: safeArray.length
+    });
+    return safeArray;
+  }
+
+  // It would be much easier to use the .getConfiguration method to obtain
+  // the normalized and safe configuration from the RTCPeerConnection
+  // instance. Unfortunately its not implemented as of Chrome unstable 59.
+  // See https://www.chromestatus.com/feature/5271355306016768
+  function protectConfiguration(configuration)
+  {
+    if (configuration == null || typeof configuration != "object")
+      return configuration;
+
+    let iceServers = safeCopyArray(
+      configuration.iceServers,
+      iceServer =>
+      {
+        let {url, urls} = iceServer;
+
+        // RTCPeerConnection doesn't iterate through pseudo Arrays of urls.
+        if (typeof urls != "undefined" && !(urls instanceof RealArray))
+          urls = [urls];
+
+        return createObject(iceServer, {
+          url: {
+            configurable: false, enumerable: false, writable: false,
+            value: normalizeUrl(url)
+          },
+          urls: {
+            configurable: false, enumerable: false, writable: false,
+            value: safeCopyArray(urls, normalizeUrl)
+          }
+        });
+      }
+    );
+
+    return createObject(configuration, {
+      iceServers: {
+        configurable: false, enumerable: false, writable: false,
+        value: iceServers
+      }
+    });
+  }
+
+  function checkUrl(peerconnection, url)
+  {
+    checkRequest("WEBRTC", url, blocked =>
+    {
+      if (blocked)
+      {
+        // Calling .close() throws if already closed.
+        try
+        {
+          closeRTCPeerConnection(peerconnection);
+        }
+        catch (e) {}
+      }
+    });
+  }
+
+  function checkConfiguration(peerconnection, configuration)
+  {
+    if (configuration && configuration.iceServers)
+    {
+      for (let i = 0; i < configuration.iceServers.length; i++)
+      {
+        let iceServer = configuration.iceServers[i];
+        if (iceServer)
+        {
+          if (iceServer.url)
+            checkUrl(peerconnection, iceServer.url);
+
+          if (iceServer.urls)
+          {
+            for (let j = 0; j < iceServer.urls.length; j++)
+              checkUrl(peerconnection, iceServer.urls[j]);
+          }
+        }
+      }
+    }
+  }
+
+  // Chrome unstable (tested with 59) has already implemented
+  // setConfiguration, so we need to wrap that if it exists too.
+  // https://www.chromestatus.com/feature/5596193748942848
+  if (RealRTCPeerConnection.prototype.setConfiguration)
+  {
+    let realSetConfiguration = Function.prototype.call.bind(
+      RealRTCPeerConnection.prototype.setConfiguration
+    );
+
+    RealRTCPeerConnection.prototype.setConfiguration = function(configuration)
+    {
+      configuration = protectConfiguration(configuration);
+
+      // Call the real method first, so that validates the configuration for
+      // us. Also we might as well since checkRequest is asynchronous anyway.
+      realSetConfiguration(this, configuration);
+      checkConfiguration(this, configuration);
+    };
+  }
+
+  function WrappedRTCPeerConnection(...args)
+  {
+    if (!(this instanceof WrappedRTCPeerConnection))
+      return WrappedRTCPeerConnection();
+
+    let configuration = protectConfiguration(args[0]);
+    // Since the old webkitRTCPeerConnection constructor takes an optional
+    // second argument we need to take care to pass that through. Necessary
+    // for older versions of Chrome such as 49.
+    let peerconnection = new RealRTCPeerConnection(configuration, args[1]);
+    checkConfiguration(peerconnection, configuration);
+    return peerconnection;
+  }
+
+  WrappedRTCPeerConnection.prototype = RealRTCPeerConnection.prototype;
+
+  let boundWrappedRTCPeerConnection = WrappedRTCPeerConnection.bind();
+  copyProperties(RealRTCPeerConnection, boundWrappedRTCPeerConnection,
+                 ["caller", "generateCertificate", "name", "prototype"]);
+  RealRTCPeerConnection.prototype.constructor = boundWrappedRTCPeerConnection;
+
+  if ("RTCPeerConnection" in window)
+    window.RTCPeerConnection = boundWrappedRTCPeerConnection;
+  if ("webkitRTCPeerConnection" in window)
+    window.webkitRTCPeerConnection = boundWrappedRTCPeerConnection;
+};
+
+if (document instanceof HTMLDocument)
+{
+  let script = document.createElement("script");
+  script.type = "application/javascript";
+  script.async = false;
+  script.textContent = "(" + injected + ")('" + randomEventName + "');";
+  document.documentElement.appendChild(script);
+  document.documentElement.removeChild(script);
+}