Issue 1727 - Prevent circumvention via WebSocket

include.preload.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 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
@@ skipping 337 matching lines @@
 
   observer.observe(parentNode, {childList: true});
   return observer;
 }
 
 function runInPage(fn, arg)
 {
   var script = document.createElement("script");
   script.type = "application/javascript";
   script.async = false;
-
-  // include.youtube.js passes this function a RegExp which JSON.stringify would
-  // convert to "{}".
-  if (!(arg instanceof RegExp))
-    arg = JSON.stringify(arg);
-
-  script.textContent = "(" + fn + ")(" + arg + ");";
+  script.textContent = "(" + fn + ")(" + JSON.stringify(arg) + ");";
   document.documentElement.appendChild(script);
   document.documentElement.removeChild(script);
 }
 
 function protectStyleSheet(document, style)
 {
   style.id = id;
 
   runInPage(function(id)
   {
     var style = document.getElementById(id) ||
                 document.documentElement.shadowRoot.getElementById(id);
     style.removeAttribute("id");
 
     var disableables = [style, style.sheet];
     for (var i = 0; i < disableables.length; i++)
       Object.defineProperty(disableables[i], "disabled",
                             {value: false, enumerable: true});
 
-    var boundCall = Function.prototype.call.bind(Function.prototype.call);
     ["deleteRule", "removeRule"].forEach(function(method)
     {
       var original = CSSStyleSheet.prototype[method];
       CSSStyleSheet.prototype[method] = function(index)
       {
         if (this != style.sheet)
-          boundCall(original, this, index);
+          original.call(this, index);
       };
     });
   }, id);
 }
 
 // Neither Chrome[1] nor Safari allow us to intercept WebSockets, and therefore
 // some ad networks are misusing them as a way to serve adverts and circumvent
 // us. As a workaround we wrap WebSocket, preventing blocked WebSocket
 // connections from being opened.
 // [1] - https://bugs.chromium.org/p/chromium/issues/detail?id=129353
@@ skipping 15 matching lines @@
         new CustomEvent(eventName + "-" + event.detail.url, {detail: block})
       );
     });
   });
 
   runInPage(function(eventName)
   {
     // As far as possible we must track everything we use that could be
     // sabotaged by the website later in order to circumvent us.
     var RealWebSocket = WebSocket;
-    var closeWebSocket = RealWebSocket.prototype.close;
+    var closeWebSocket = Function.prototype.call.bind(RealWebSocket.prototype.close);
     var addEventListener = document.addEventListener.bind(document);
     var removeEventListener = document.removeEventListener.bind(document);
     var dispatchEvent = document.dispatchEvent.bind(document);
     var CustomEvent = window.CustomEvent;
-    var boundCall = Function.prototype.call.bind(Function.prototype.call);
-    var functionToString = Function.prototype.toString;
-    // (Safari 9 considers WebSocket to be an object rather than a function.)
-    var webSocketString = RealWebSocket.toString();
 
     function checkRequest(url, callback)
     {
       var incomingEventName = eventName + "-" + url;
       function listener(event)
       {
         callback(event.detail);
         removeEventListener(incomingEventName, listener);
       }
       addEventListener(incomingEventName, listener);
 
       dispatchEvent(new CustomEvent(eventName, {
         detail: {url: url}
       }));
     }
 
-    function wrappedToString()
-    {
-      if (this === WebSocket)
-        return webSocketString;
-      if (this === wrappedToString)
-        return boundCall(functionToString, functionToString);
-      return boundCall(functionToString, this);
-    };
-    Function.prototype.toString = wrappedToString;
-
-    WebSocket = function(url, protocols)
-    {
+    WebSocket = function WrappedWebSocket(url, protocols)
+    {
+      // Throw correct exceptions if the constructor is used improperly.
+      if (!(this instanceof WrappedWebSocket)) return RealWebSocket();
+      if (arguments.length < 1) return new RealWebSocket();
+
       var websocket = new RealWebSocket(url, protocols);
 
       checkRequest(websocket.url, function(blocked)
       {
         if (blocked)
-          boundCall(closeWebSocket, websocket);
+          closeWebSocket(websocket);
       });
 
       return websocket;
-    };
-
-    var properties = Object.getOwnPropertyNames(RealWebSocket);
-    for (var i = 0; i < properties.length; i++)
-    {
-      var name = properties[i];
-      var desc = Object.getOwnPropertyDescriptor(RealWebSocket, name);
-      Object.defineProperty(WebSocket, name, desc);
-    }
+    }.bind();
+
+    Object.defineProperties(WebSocket, {
+      CONNECTING: {value: RealWebSocket.CONNECTING, enumerable: true},
+      OPEN: {value: RealWebSocket.OPEN, enumerable: true},
+      CLOSING: {value: RealWebSocket.CLOSING, enumerable: true},
+      CLOSED: {value: RealWebSocket.CLOSED, enumerable: true},
+      prototype: {value: RealWebSocket.prototype}
+    });
 
     RealWebSocket.prototype.constructor = WebSocket;
   }, eventName);
 }
 
 function init(document)
 {
   var shadow = null;
   var style = null;
   var observer = null;
@@ skipping 164 matching lines @@
   }, true);
 
   return updateStylesheet;
 }
 
 if (document instanceof HTMLDocument)
 {
   checkSitekey();
   window.updateStylesheet = init(document);
 }