eyeo's WebExtension Ad-Filtering Solution

This is a library that provides integration of eyeo's Ad Blocking Core for Chromium and Firefox extensions (like Adblock Plus). The Ad Blocking Core is in the adblockpluscore directory. See the content of that directory for further information.

Code of Conduct

All contributors to this project are required to read, and follow, our code of conduct.

Directory structure

core/sdk/
├── adblockpluscore/        # adblockpluscore ad-filtering engine
├── docs/                   # Documentation
├── dist/                   # SDK distribution files
├── scripts/                # Build scripts and tooling
├── src/                    # SDK Source code
│   ├── all/ (or shared/)     # Code for any execution context
│   ├── background/           # Code for background process
│   ├── content/              # Code for isolated world
│   ├── front/                # Code for UI page and isolated world
│   └── main/                 # Code for main world
└── test/                   # Functional tests

SDK source code is grouped by execution context.

Getting started

The library comes in four parts:

• ewe-api.js to be included in the extension's background page
• ewe-content.js to be loaded as a content script (isolated world)
• ewe-content-main.js to be loaded as a content script (main world)
• ewe-content-api.js to be imported in the extension's various content scripts
• ewe-ui.js to be loaded in the extension's various UI pages

You can get it from npm.

Additionally, the SDK provides standalone utilities that can work in both browser extension contexts, as well as other Javascript contexts.

With two versions of the API, Manifest V2 and Manifest V3, there are two different manifest that are needed depending on which API you target.

Supported browsers

The webext-ad-filtering-solution (as a short term we use 'engine') is tested on the following versions:

Manifest V2:

• Chromium 127 and latest
• Firefox 128 and latest
• Edge latest

Chromium 129 and newer do not support MV2 web extensions, so version "128.0.6613.0" is used for MV2 testing.

Manifest V3:

• Chromium 127 and latest
• Edge latest
• Safari latest - iOS and macOS (limited support)

List of browsers supported by extension and webext can be found in the supported-browsers.

Manifest for V2

For Manifest V2, the extension's manifest.json is required to include the following configuration:

{
  "manifest_version": 2,
  "background": {
    "scripts": [
      "ewe-api.js"
    ]
  },
  "content_scripts": [
    {
      "all_frames": true,
      "js": [
        "ewe-content.js"
      ],
      "match_about_blank": true,
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "run_at": "document_start"
    }
  ],
  "permissions": [
    "webNavigation",
    "webRequest",
    "webRequestBlocking",
    "scripting",
    "storage",
    "unlimitedStorage",
    "tabs",
    "<all_urls>"
  ]
}

Manifest for V3

For Manifest V3, the extension's manifest.json is required to include the following configuration:

{
  "manifest_version": 3,
  "background": {
    "service_worker": "background.js"
  },
  "content_scripts": [
    {
      "all_frames": true,
      "js": [
        "ewe-content.js"
      ],
      "match_about_blank": true,
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "run_at": "document_start"
    }
  ],
  "permissions": [
    "declarativeNetRequest",
    "scripting",
    "storage",
    "tabs",
    "webNavigation",
    "webRequest",
    "unlimitedStorage"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "declarative_net_request": <output from "subs-generate" script>
}

The example above requires a couple of changes and can't be used as-is.

The service_worker value needs be set to your built file for the background script, that includes ewe-api.js.

Please note that for the sample above, you need to make sure to set the value of declarative_net_request properly, as shown in the decalrativeNetRequest documentation. This mean you also need to add to your extension build the files that contains the rulesets declared in this section, as well as the text filter lists. Refer to the Manifest V3 documentation for more details.

The permission declarativeNetRequestWithHostAccess requires the host_permissions to be <all_urls>. You could use the declarativeNetRequest permission without setting host_permissions. But it would have the effect of preventing the filtering of content and limiting the blocking to network requests to those specified in host_permissions. The default configuration provided offers the most functionality.

Required permissions and why we need them

We require several permissions for the WebExt Ad-Filtering Solution to function correctly. The manifest file templates above include the required permissions. Here is why we need each one:

• webNavigation: Gives access to the Web Navigation API, which we use to apply document-level allowing filters and to block popups.
• webRequest: Gives access to the Web Request API. Used to apply URL filters in MV2, and to report on URL filters in MV3. Also used to retrieve sitekeys for a site.
• webRequestBlocking (MV2 only): Allows blocking request based on URL filters in MV2.
• declarativeNetRequest (MV3 only): Gives access to the Declarative Net Request API, which we use to apply URL filters in MV3.
• storage: Gives access to storage APIs, which we use to store downloaded subscriptions, user's custom filters, etc.
• unlimitedStorage: By default, extensions are only allowed 5MB of storage, which isn't enough for larger subscriptions. This permission removes that limit.
• tabs: Gives access to some tab metadata, including the tab's URL, which is used to apply document-level allowing filters to the tab.
• scripting: (MV3 and Firefox MV2 only) Used to apply content filters, including element hiding filters and snippet filters.
• <all_urls>: Allows the WebExt Ad-Filtering Solution to act on all websites. Note that in MV2 manifests this goes in the permissions, but in MV3 manifests this goes in the new host_permissions section.

You can read more about browser extension permissions and their effects in Google's docs for MV2 permissions and MV3 permissions

API

The API will be available in your own background scripts and UI pages through the global EWE object. In the background scripts, please call EWE.start() to start blocking ads.

At minimum the following information need to be passed to EWE.start():

• bundledSubscriptions (only Manifest v3)
  List of subscriptions that can be found at bundledSubscriptionsPath
• bundledSubscriptionsPath (only Manifest v3)
  Path to directory in the extension build containing ABP-syntax filter list files
  e.g. /data/rules/abp
• heavyDependenciesPath
  Path to dist/ewe-heavy-dependencies.js file in the extension build
  e.g. /vendor/@eyeo/webext-ad-filtering-solution/heavy-dependencies.js

Note that in MV3 extensions, EWE.start() must be called in the first turn of the event loop of the service worker, so that it can attach event listeners.

Module bundlers (optional)

ewe-api.js and ewe-ui.js are built as a UMD module (Universal Module Definition), and so they can also be used with module bundlers.

If using a module bundler for the background script, do not add ewe-api.js to your manifest.json. Similarly, if using a module bundler for scripts on UI pages, do not add ewe-ui.js to your UI pages. Consequently, there won't be a global EWE object.

CommonJS

const EWE = require("@eyeo/webext-ad-filtering-solution");
EWE.start(addonInfo);

ESM

import * as EWE from "@eyeo/webext-ad-filtering-solution";
EWE.start(addonInfo);

You can also import the content script. This should only be included once by an extension, since it starts running the content scripts without the need to call any sort of "start" function.

import "@eyeo/webext-ad-filtering-solution/content";

Individual utilities that can be used in any context can also be imported.

import {Scheduler} from "@eyeo/webext-ad-filtering-solution/all/scheduler.js";

Functionality that is intended to run in a UI context (popup, options, etc.) will use the ewe-ui.js file. This can be imported in those pages either by using the mechanism below in a ui page:

import * as EWE from "@eyeo/webext-ad-filtering-solution/ui";

or by handling the bundling and importing the generated file directly:

<script src="ewe-ui.js"></script>

Functionality that is intended to run in a content script context will use the ewe-content-api.js file. This can be imported by using the mechanism below:

import * as EWE from "@eyeo/webext-ad-filtering-solution/content-api";

Snippet filters support

The snippets library is available by default to EWE. Consult the documentation for snippet filters to learn how to use them.

Shared resources

There are some shared resources that are used by both webext-ad-filtering-solution & production code:

• browser
  • Global is set by webextension-polyfill version 0.8.0.
• browser.runtime.connect()/browser.runtime.onConnect
  • Channel name is prefixed with "ewe:".
• browser.runtime.sendMessage()/browser.runtime.onMessage
  • Our messages are objects with a "type" property whose value is prefixed with "ewe:".
• indexedDB.open()
  • Database name is prefixed with "EWE".
• Web page links
  • Links used by module are prefixed with "abp:" or "https://subscribe.adblockplus.org/".
• browser.storage.local and browser.storage.session
  • Storage keys are prefixed with either "ewe:" or "abp:pref:".

During initialization the engine migrates legacy data from local storage to indexedDB. Files migrated have to be prefixed: file:. Files prefixed with file:/// will be ignored.

Notifications support

Using the notifications module is optional. To start using it, an initialisation is required:

EWE.notifications.start();

One Click Allowlisting support

To enable One Click Allowlisting, you need to set the list of authorized public keys that can be used to authenticate allowlisting requests.

EWE.allowlisting.setAuthorizedKeys(keys);

See the allowlisting module docs for more detail.

New keypairs can be created with the correct algorithm and settings by using our keypair creation script.

npm run -w @eyeo/webext-ad-filtering-solution create-allowlisting-keypair

See the Development section below for details on running our scripts and other EWE development tasks. Keys can also be generated using other programs like OpenSSL. The keys use the RSASSA-PKCS1-v1_5 algorithm, SHA512 hash and 4096 bit long modulus. Additionally, when passed to setAuthorizedKeys, the keys should be base64 encoded strings, in SPKI format.

npm install

npm run build -- --scope @eyeo/webext-ad-filtering-solution

cd core/sdk/
npx webpack --watch

npm run build -- --scope @eyeo/webext-ad-filtering-solution -- --help

# Build only engine, no test extensions
npm run build -- --scope @eyeo/webext-ad-filtering-solution -- --config-name engine

# Don't generate any sourcemaps
npm run build -- --scope @eyeo/webext-ad-filtering-solution -- --no-devtool

npm run build -- --scope @eyeo/webext-ad-filtering-solution -- --force-subscription-update

npm run -w @eyeo/test-utils start-sdk-server &
npm run build -- --scope @eyeo/webext-ad-filtering-solution -- --use-external-server

npm run build:release -- --scope @eyeo/webext-ad-filtering-solution

npm run -w @eyeo/webext-ad-filtering-solution docs

npm run lint

Testing

For full documentation about testing please refer to our testing document.

Publishing

The SDK is published to npm according to the SDK release process.

Events

The library provides the listeners to observe the events:

• EWE.allowlisting.onUnauthorized: Emitted when an allowlisting request is rejected
• EWE.filters:
  • onAdded: Emitted when a new filter is added
  • onChanged: Emitted when a filter is either enabled or disabled or metadata changed
  • onRemoved: Emitted when a filter is removed
• EWE.subscriptions:
  • onAdded: Emitted when a new subscription is added
  • onChanged: Emitted when any property of the subscription has changed
  • onRemoved: Emitted when a subscription is removed
• EWE.debugging.onLogEvent: Emitted when having debug output
• EWE.reporting.onBlockableItem: Emitted when any blockable item is matched

Use addListener(...) to subscribe and removeListener(...) to unsubscribe.

Manifest V3

See the Manifest V3 documentation for further explanations.