Issue 5027 - Use updated webRequest API for WebSocket blocking

lib/requestBlocker.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
@@ skipping 134 matching lines @@
 
 FilterNotifier.on("subscription.added", onFilterChange);
 FilterNotifier.on("subscription.removed", onFilterChange);
 FilterNotifier.on("subscription.updated", onFilterChange);
 FilterNotifier.on("subscription.disabled", arg => onFilterChange(arg, true));
 FilterNotifier.on("filter.added", onFilterChange);
 FilterNotifier.on("filter.removed", onFilterChange);
 FilterNotifier.on("filter.disabled", arg => onFilterChange(arg, true));
 FilterNotifier.on("load", onFilterChange);
 
-port.on("request.websocket", (msg, sender) =>
+// On Chrome <58, the webRequest API doesn't intercept WebSocket connections,
+// see https://crbug.com/129353.
+//
+// Hence we patched the WebSocket object as a workaround. WebSocket connections
+// detected by this workaround are handled below.
+if (!("WEBSOCKET" in chrome.webRequest.ResourceType))
 {
-  return ext.webRequest.onBeforeRequest._dispatch(
-    new URL(msg.url),
-    "WEBSOCKET",
-    sender.page,
-    sender.frame
-  ).indexOf(false) != -1;
-});
+  port.on("request.websocket", (msg, sender) =>
+  {
+    return ext.webRequest.onBeforeRequest._dispatch(
+      new URL(msg.url),
+      "WEBSOCKET",
+      sender.page,
+      sender.frame
+    ).indexOf(false) != -1;
+  });
+}