Issue 3687 - Add experimental support for Safari content blockers

safari/contentBlocking.js

Index: safari/contentBlocking.js
diff --git a/safari/contentBlocking.js b/safari/contentBlocking.js
new file mode 100644
index 0000000000000000000000000000000000000000..d04b08a28649549e2577a109334fedb8b8a3c74e
--- /dev/null
+++ b/safari/contentBlocking.js
@@ -0,0 +1,150 @@
+/*
+ * 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
+ * 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 contentBlocking */
+
+"use strict";
+
+let {Prefs} = require("prefs");
+let {ContentBlockerList} = require("abp2blocklist");
+let {FilterStorage} = require("filterStorage");
+let {FilterNotifier} = require("filterNotifier");
+let {port} = require("messaging");
+
+let contentBlockingSupported = "setContentBlocker" in safari.extension;
+let legacyApiSupported = "onbeforeload" in Element.prototype;

[kzar, 2016/04/19 14:03:49]

I remember you said we shouldn't assume both onbeforeload and canLoad will be
removed at the same time, but I can't see how else to do this. (We don't know
about canLoad here and we need to make a decision.)

[Sebastian Noack, 2016/05/12 11:12:23]

You could detect the legacy API in the content script, send the result with the
"loading" message, make legacyApiSupported a promise and resolve it when the
first loading message arrives.

[kzar, 2016/05/17 15:15:39]

Done.

+let contentBlockingActive = contentBlockingSupported && !legacyApiSupported;
+let afterContentBlockingFinished;

[Sebastian Noack, 2016/05/12 11:12:23]

If I understand the logic correctly, this variable might be accessed before
assigned. So initialize it with null here?

[kzar, 2016/05/17 15:15:39]

Done.

+let contentBlockListDirty = true;
+let lastSetContentBlockerResult;
+
+function clearBlockCounters()
+{
+  ext.pages.query({}, pages =>
+  {
+    for (let page of pages)
+      page.browserAction.setBadge();
+  });
+}
+
+function setContentBlocker(callback)
+{
+  // setContentBlocker returns null if given the same blocklist as last time,
+  // even when there was an error. (It's also wasteful to re-generate the
+  // blocklist when nothing has changed!)
+  if (!contentBlockListDirty)
+  {
+    callback(lastSetContentBlockerResult);
+    return;
+  }
+
+  let contentBlockerList = new ContentBlockerList();
+  for (let subscription of FilterStorage.subscriptions)
+    if (!subscription.disabled)
+      for (let filter of subscription.filters)
+        contentBlockerList.addFilter(filter);
+
+  safari.extension.setContentBlocker(
+    // setContentBlocker seems to work unreliably in Safari 9 unless the the
+    // given rules are converted to JSON first. (An error is sometimes thrown:
+    // "Extension compilation failed: Failed to parse the JSON String.")
+    JSON.stringify(contentBlockerList.generateRules()),

[Sebastian Noack, 2016/05/12 11:12:23]

That needs to be tracked down properly. If there is no way around then there is
no way around. But I'd rather avoid converting this huge array to a string just
to have Safari internally parse it again, if possible.

[kzar, 2016/05/17 15:15:39]

OK, I'll try again to figure out what's going on.

+    function (result)
+    {
+      contentBlockListDirty = false;
+      lastSetContentBlockerResult = result;
+      callback(result);
+    }
+  );
+}
+
+function updateContentBlocker(onStartup)

[Sebastian Noack, 2016/05/12 11:12:23]

Nit: onStartup -> isStartup, since this value indicated whether this is the
startup not what to do on startup.

[kzar, 2016/05/17 15:15:39]

Done.

+{
+  afterContentBlockingFinished = new Promise(resolve =>
+  {
+    setContentBlocker(result =>
+    {
+      if (result instanceof Error)
+      {
+        let suppressErrorMessage = false;
+
+        // If the content blocking API fails the first time it's used the
+        // legacy blocking API (if available) won't have been disabled.
+        if (!contentBlockingActive && legacyApiSupported)
+        {
+          Prefs["safariContentBlocker"] = false;
+          Prefs.on("safariContentBlocker", onSafariContentBlocker);
+          // If content blocking failed on startup and we're switching back to
+          // the legacy API anyway we don't need to show an error message.
+          if (onStartup)
+            suppressErrorMessage = true;
+        }
+
+        if (!suppressErrorMessage)
+          alert(result.message);
+      }
+      else if (!contentBlockingActive)
+      {
+        contentBlockingActive = true;
+        clearBlockCounters();
+      }
+
+      resolve(contentBlockingActive);
+      afterContentBlockingFinished = undefined;
+    });
+  });
+}
+
+function onSafariContentBlocker()
+{
+  Prefs.off("safariContentBlocker", onSafariContentBlocker);
+  updateContentBlocker();
+}
+
+if (contentBlockingSupported)
+{
+  Promise.all([Prefs.untilLoaded, FilterNotifier.once("load")]).then(() =>
+  {
+    // If this version of Safari only supports the new API then let's make sure
+    // the safariContentBlocker preference is set to true for consistency.
+    if (contentBlockingActive)
+      Prefs["safariContentBlocker"] = true;
+
+    if (Prefs["safariContentBlocker"])

[Sebastian Noack, 2016/05/12 11:12:23]

Nit: Prefs.safariContentBlocker

[kzar, 2016/05/17 15:15:38]

Done.

+      updateContentBlocker(true);
+    else
+      Prefs.on("safariContentBlocker", onSafariContentBlocker);

[Sebastian Noack, 2016/05/12 11:12:23]

I wonder whether the logic wouldn't be simpler if you simply always register
Prefs.on("safariContentBlocker", ) if content blocking is supported and never
unregister it, rather than registering and unregistering it in different places.

[kzar, 2016/05/17 15:15:40]

Done.

+
+    for (let action of ["load", "subscription.added", "subscription.removed",

[Sebastian Noack, 2016/05/12 11:12:23]

As usual, jsHydra will duplicate that array in the generated code. Anyway, it
seems that you only need to listen for "filter.behaviorChanged" here.

[kzar, 2016/05/17 15:15:38]

Done.

+                        "subscription.updated", "subscription.disabled",
+                        "filter.added", "filter.removed", "filter.disabled"])
+      FilterNotifier.on(action, () =>
+      {
+        contentBlockListDirty = true;
+        if (contentBlockingActive)
+          updateContentBlocker();
+      });
+  });
+}
+
+port.on("safari.contentBlockingActive", function(msg, sender)
+{
+  if (!contentBlockingActive && afterContentBlockingFinished)
+    return afterContentBlockingFinished;
+  return contentBlockingActive;
+});
+