Issue 6622 - Implement $rewrite filter option

lib/requestBlocker.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * 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
@@ skipping 52 matching lines @@
   if (!(browser.webRequest.ResourceType))
     return;
 
   for (let type in browser.webRequest.ResourceType)
     yield resourceTypes.get(browser.webRequest.ResourceType[type]) || "OTHER";
 
   // WEBRTC gets addressed through a workaround, even if the webRequest API is
   // lacking support to block this kind of a request.
   yield "WEBRTC";
 
-  // POPUP, CSP and ELEMHIDE filters aren't mapped to resource types.
+  // These filter types aren't mapped to resource types.
   yield "POPUP";
   yield "ELEMHIDE";
   yield "CSP";
 }());
 
 function getDocumentInfo(page, frame, originUrl)
 {
   return [
     extractHostFromFrame(frame, originUrl),
     getKey(page, frame, originUrl),
@@ skipping 32 matching lines @@
     url = details.initiator + "/*";  // is equivalent to "originUrl" on Firefox
                                      // except that its not a full URL but just
                                      // an origin (proto + host).
   else
     return Promise.resolve([]);
 
   return browser.tabs.query({url}).then(tabs => tabs.map(tab => tab.id));
 }
 
 function logRequest(tabIds, url, type, docDomain, thirdParty,
-                    sitekey, specificOnly, filter)
+                    sitekey, specificOnly, filter, rewrittenTo)
 {
   if (filter)
     FilterNotifier.emit("filter.hitCount", filter, 0, 0, tabIds);
 
   devtools.logRequest(
     tabIds, url, type, docDomain,
     thirdParty, sitekey,
-    specificOnly, filter
+    specificOnly, filter, rewrittenTo
   );
 }
 
 browser.webRequest.onBeforeRequest.addListener(details =>
 {
   // Never block top-level documents.
   if (details.type == "main_frame")
     return;
 
   // Filter out requests from non web protocols. Ideally, we'd explicitly
@@ skipping 42 matching lines @@
 
   if (checkWhitelisted(page, frame, originUrl))
     return;
 
   let type = resourceTypes.get(details.type) || "OTHER";
   let [docDomain, sitekey, specificOnly] = getDocumentInfo(page, frame,
                                                            originUrl);
   let [filter, urlString, thirdParty] = matchRequest(url, type, docDomain,
                                                      sitekey, specificOnly);
 
+  let result;
+  let rewrittenTo;
+
+  if (filter instanceof BlockingFilter)
+  {
+    if (filter.rewrite)
+    {
+      let rewritten = filter.rewriteUrl(urlString);
+      if (rewritten == urlString)
+        // we couldn't do the rewrite, so just let it through.
+        return;
+
+      rewrittenTo = rewritten;
+      result = {redirectUrl: rewritten};
+    }
+    else
+      result = {cancel: true};
+  }
+
   getRelatedTabIds(details).then(tabIds =>
   {
     logRequest(tabIds, urlString, type, docDomain,
-               thirdParty, sitekey, specificOnly, filter);
+               thirdParty, sitekey, specificOnly, filter, rewrittenTo);
   });
 
-  if (filter instanceof BlockingFilter)
-    return {cancel: true};
+  return result;
 }, {urls: ["<all_urls>"]}, ["blocking"]);
 
 port.on("filters.collapse", (message, sender) =>
 {
   let {page, frame} = sender;
 
   if (checkWhitelisted(page, frame))
     return false;
 
   let blocked = false;
@@ skipping 94 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);