Issue 6539, 6782 - Implement support for snippets

lib/contentFiltering.js

Index: lib/contentFiltering.js
===================================================================
rename from lib/cssInjection.js
rename to lib/contentFiltering.js
--- a/lib/cssInjection.js
+++ b/lib/contentFiltering.js
@@ -10,39 +10,43 @@
  * 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/>.
  */
 
-/** @module cssInjection */
+/** @module contentFiltering */
 
 "use strict";
 
 const {RegExpFilter} = require("../adblockpluscore/lib/filterClasses");
 const {ElemHide} = require("../adblockpluscore/lib/elemHide");
 const {ElemHideEmulation} = require("../adblockpluscore/lib/elemHideEmulation");
+const {Snippets, compileScript} = require("../adblockpluscore/lib/snippets");
 const {checkWhitelisted} = require("./whitelisting");
 const {extractHostFromFrame} = require("./url");
 const {port} = require("./messaging");
 const {HitLogger} = require("./hitLogger");
 const info = require("info");
 
 // Chromium's support for tabs.removeCSS is still a work in progress and the
 // API is likely to be different from Firefox's; for now we just don't use it
 // at all, even if it's available.
 // See https://crbug.com/608854
 const styleSheetRemovalSupported = info.platform == "gecko";
 
 const selectorGroupSize = 1024;
 
 let userStyleSheetsSupported = true;
 
+let snippetsLibrarySource = "";
+let executableCode = new Map();
+
 function* splitSelectors(selectors)
 {
   // Chromium's Blink engine supports only up to 8,192 simple selectors, and
   // even fewer compound selectors, in a rule. The exact number of selectors
   // that would work depends on their sizes (e.g. "#foo .bar" has a size of 2).
   // Since we don't know the sizes of the selectors here, we simply split them
   // into groups of 1,024, based on the reasonable assumption that the average
   // selector won't have a size greater than 8. The alternative would be to
@@ -90,17 +94,17 @@
       userStyleSheetsSupported = false;
 
     // For other errors, we simply return false to indicate failure.
     //
     // One common error that occurs frequently is when a frame is not found
     // (e.g. "Error: No frame with id 574 in tab 266"), which can happen when
     // the code in the parent document has removed the frame before the
     // background page has had a chance to respond to the content script's
-    // "elemhide.getSelectors" message. We simply ignore such errors, because
+    // "content.applyFilters" message. We simply ignore such errors, because
     // otherwise they show up in the log too often and make debugging
     // difficult.
     //
     // Also note that the missing frame error is thrown synchronously on
     // Firefox, while on Chromium it is an asychronous promise rejection. In
     // the latter case, we cannot indicate failure to the caller, but we still
     // explicitly ignore the error.
     return false;
@@ -155,35 +159,86 @@
   // style sheet now.
   if (oldStyleSheet && oldStyleSheet != styleSheet)
     removeStyleSheet(tabId, frameId, oldStyleSheet);
 
   frame.injectedStyleSheets.set(groupName, styleSheet);
   return true;
 }
 
-port.on("elemhide.getSelectors", (message, sender) =>
+function getExecutableCode(script)
+{
+  let code = executableCode.get(script);
+  if (code)
+    return code;
+
+  code = compileScript(script, [snippetsLibrarySource]);
+
+  executableCode.set(script, code);
+  return code;
+}
+
+function executeScript(script, tabId, frameId)
+{
+  try
+  {
+    browser.tabs.executeScript(tabId, {
+      code: getExecutableCode(script),
+      frameId,
+      matchAboutBlank: true,
+      runAt: "document_start"
+    })
+    .catch(error =>
+    {
+      // Sometimes a frame is added and removed very quickly, in such cases we
+      // simply ignore the error.
+      if (error.message == "The frame was removed.")
+        return;
+
+      throw error;
+    });
+  }
+  catch (error)
+  {
+    // See the comment in the catch block associated with the call to
+    // tabs.insertCSS for why we catch and ignore any errors here.
+  }
+}
+
+port.on("content.applyFilters", (message, sender) =>
 {
   let selectors = [];
   let emulatedPatterns = [];
   let trace = HitLogger.hasListener(sender.page.id);
   let inline = !userStyleSheetsSupported;
 
+  let {elemhide, snippets} = message.filterTypes ||
+                             {elemhide: true, snippets: true};
+
   if (!checkWhitelisted(sender.page, sender.frame, null,
-                        RegExpFilter.typeMap.DOCUMENT |
-                        RegExpFilter.typeMap.ELEMHIDE))
+                        RegExpFilter.typeMap.DOCUMENT))
   {
     let hostname = extractHostFromFrame(sender.frame);
-    let specificOnly = checkWhitelisted(sender.page, sender.frame, null,
-                                        RegExpFilter.typeMap.GENERICHIDE);
+
+    if (snippets)
+    {
+      for (let script of Snippets.getScriptsForDomain(hostname))
+        executeScript(script, sender.page.id, sender.frame.id);
+    }
 
-    selectors = ElemHide.getSelectorsForDomain(hostname, specificOnly);
+    if (elemhide && !checkWhitelisted(sender.page, sender.frame, null,
+                                      RegExpFilter.typeMap.ELEMHIDE))
+    {
+      let specificOnly = checkWhitelisted(sender.page, sender.frame, null,
+                                          RegExpFilter.typeMap.GENERICHIDE);
+      selectors = ElemHide.getSelectorsForDomain(hostname, specificOnly);
 
-    for (let filter of ElemHideEmulation.getRulesForDomain(hostname))
-      emulatedPatterns.push({selector: filter.selector, text: filter.text});
+      for (let filter of ElemHideEmulation.getRulesForDomain(hostname))
+        emulatedPatterns.push({selector: filter.selector, text: filter.text});
+    }
   }
 
   if (!inline && !updateFrameStyles(sender.page.id, sender.frame.id,
                                     selectors, "standard"))
   {
     inline = true;
   }
 
@@ -201,8 +256,15 @@
   return response;
 });
 
 port.on("elemhide.injectSelectors", (message, sender) =>
 {
   updateFrameStyles(sender.page.id, sender.frame.id, message.selectors,
                     message.groupName, message.appendOnly);
 });
+
+fetch(browser.extension.getURL("/snippets.js"), {cache: "no-cache"})
+.then(response => response.ok ? response.text() : "")
+.then(text =>
+{
+  snippetsLibrarySource = text;
+});