Issue 5316 - Adds supported filter types export value to requestBlocker

lib/requestBlocker.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
- * Copyright (C) 2006-2017 eyeo GmbH
+ * Copyright (C) 2006-present 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.
  *
@@ skipping 32 matching lines @@
   yield ["sub_frame", "SUBDOCUMENT"];
 
   // Treat navigator.sendBeacon() the same as <a ping>, it's essentially the
   // same concept - merely generalized.
   yield ["beacon", "PING"];
 
   // Treat <img srcset> and <picture> the same as other images.
   yield ["imageset", "IMAGE"];
 }());
 
-// Expose supported resource types for devtools panel

[Jon Sonesen, 2017/08/21 15:33:07]

I think this comment could be improved but not sure if it is that important,
since it seems clear what the code is doing.

[Sebastian Noack, 2017/08/22 09:47:28]

Yeah, I'd rather just remove that comment.

[Jon Sonesen, 2017/09/01 08:09:06]

Acknowledged.

 exports.filterTypes = new Set(function*()
 {
+  // Microsoft Edge does not have webRequest.ResourceType or the devtools panel.
+  // Since filterTypes is only used by devtools, we can just bail out here.
+  if (!(chrome.webRequest.ResourceType))
+    return;
+
   for (let type in chrome.webRequest.ResourceType)

[Sebastian Noack, 2017/08/22 09:47:28]

webRequest.ResourceType doesn't exist in Microsoft Edge. However, neither does
the devtools panel, so the value of filterTypes is irrelevant there, but we
still have to detect whether ResourceType exists in order to prevent this script
from throwing an error on Microsoft Edge.

[Jon Sonesen, 2017/09/01 08:09:06]

Cool, can I just return if !(chrome.webRequest.ResourceType)?

[Sebastian Noack, 2017/09/05 18:08:10]

Yes, that will do.

     yield resourceTypes.get(chrome.webRequest.ResourceType[type]) || "OTHER";

[Sebastian Noack, 2017/08/22 09:47:28]

There are some filter types which we need to hard-code here, in addition to
those which we can detect based on webRequest.ResourceType. These are:

* WEBSOCKET (supported through a workaround if not in ResourceType)
* WEBRTC (supported through a workaround)
* POPUP (non-request type)
* ELEMHIDE (non-request type)

[Jon Sonesen, 2017/09/01 08:09:06]

Cool, does it make sense to just add yields with each type after the iteration?

[Sebastian Noack, 2017/09/05 18:08:10]

Yes, I think this is the simplest approach.

+
+  // WEBSOCKET and WEBRTC get addressed through workarounds, even if the
+  // webRequest API is lacking support to block these kind of requests.
+  yield "WEBSOCKET";
+  yield "WEBRTC";
+
+  // POPUP and ELEMHIDE filters aren't blocked on the request level but by other
+  // means. They don't have a corresponding value in webRequest.ResourceType.
+  yield "POPUP";
+  yield "ELEMHIDE";
 }());
 
 function onBeforeRequestAsync(page, url, type, docDomain,
                               thirdParty, sitekey,
                               specificOnly, filter)
 {
   if (filter)
     FilterNotifier.emit("filter.hitCount", filter, 0, 0, page);
 
   if (devtools)
@@ skipping 133 matching lines @@
     return false;
   }
 
   return ext.webRequest.onBeforeRequest._dispatch(
      new URL(msg.url),
      msg.requestType,
      sender.page,
      sender.frame
   ).includes(false);
 });