Add declarativeNetRequest (DNR) + MV3 examples (#526)

These examples are designed to be cross-browser compatible. In particular, these extensions do not use `background` because there is currently no single manifest that can support both Firefox and Chrome, due to the lack of event page support in Chrome, and the lack of service worker support in Firefox. Three examples demonstrating the use of the declarativeNetRequest API: - dnr-block-only: One minimal example demonstrating the use of static DNR rules to block requests. - dnr-redirect-url: One minimal example demonstrating the use of static DNR rules to redirect requests. - dnr-dynamic-with-options: A generic example demonstrating how host permissions can be requested and free forms to input DNR rules.
mdn · May 17, 2023 · 06330a6 · 06330a6
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diff --git a/.eslintrc.json b/.eslintrc.json
@@ -8,12 +8,15 @@
     "es6": true,
     "webextensions": true
   },
+  "globals": {
+    "globalThis": false
+  },
   "extends": [
     "eslint:recommended"
   ],
   "rules": {
     "no-console": 0,
-    "no-unused-vars": ["warn", { "vars": "all", "args": "all" } ],
+    "no-unused-vars": ["warn", { "vars": "all", "args": "after-used" } ],
     "no-undef": ["warn"],
     "no-proto": ["error"],
     "prefer-arrow-callback": ["warn"],

diff --git a/dnr-block-only/README.md b/dnr-block-only/README.md
@@ -0,0 +1,42 @@
+# dnr-block-only
+
+Demonstrates how to block network requests without host permissions using the
+declarativeNetRequest API with the `declarative_net_request` manifest key.
+
+## What it does
+
+This extension blocks:
+
+- network requests to URLs containing "blocksub" (except for top-level
+  navigations).
+- top-level navigation to URLs containing "blocktop".
+- all requests containing "blockall".
+
+Load `testpage.html` to see the extension in action.
+This demo page does not need to be packaged with the extension.
+
+# What it shows
+
+This example shows how to:
+
+- use the declarativeNetRequest API through the `declarative_net_request`
+  manifest key.
+- use the "resourceTypes" and "excludedResourceTypes" conditions of a
+  declarativeNetRequest rule.
+- block network requests without host permissions using the
+  "declarativeNetRequest" permission, which triggers the "Block content on any
+  page" permission warning at install time.
+
+This example is the only cross-browser way to block network requests (at least
+in Firefox, Chrome, and Safari). The webRequest API is an alternative way to
+implement this functionality, but is only available in Firefox (MV2 and MV3)
+and in Chrome (MV2 only). Safari does not support the webRequest API.
+
+## Comparison with Manifest Version 2
+
+While this example uses `"manifest_version": 3`, the functionality is not
+specific to Manifest Version 3.
+
+To create a MV2 version of the extension, modify `manifest.json` as follows:
+
+- Set `manifest_version` to 2.
diff --git a/dnr-block-only/manifest.json b/dnr-block-only/manifest.json
@@ -0,0 +1,16 @@
+{
+  "manifest_version": 3,
+  "name": "Block only, without host_permissions",
+  "description": "Blocks requests to 'blocksub', 'blocktop', and 'blockall'. Uses the 'declarativeNetRequest' permission, meaning that host_permissions in manifest.json are not needed.",
+  "version": "0.1",
+  "permissions": [
+      "declarativeNetRequest"
+  ],
+  "declarative_net_request": {
+    "rule_resources": [{
+      "id": "ruleset",
+      "enabled": true,
+      "path": "rules.json"
+    }]
+  }
+}
diff --git a/dnr-block-only/rules.json b/dnr-block-only/rules.json
@@ -0,0 +1,31 @@
+[
+  {
+    "id": 1,
+    "condition": {
+      "urlFilter": "blocksub"
+    },
+    "action": {
+      "type": "block"
+    }
+  },
+  {
+    "id": 2,
+    "condition": {
+      "urlFilter": "blocktop",
+      "resourceTypes": ["main_frame"]
+    },
+    "action": {
+      "type": "block"
+    }
+  },
+  {
+    "id": 3,
+    "condition": {
+      "urlFilter": "blockall",
+      "excludedResourceTypes": []
+    },
+    "action": {
+      "type": "block"
+    }
+  }
+]
diff --git a/dnr-block-only/testpage.html b/dnr-block-only/testpage.html
@@ -0,0 +1,97 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<style>
+div {
+  margin: 2px 0;
+  border: 1px solid black;
+}
+img {
+  display: block;
+}
+</style>
+</head>
+<body>
+
+<h2 id="blocksub">Block requests containing 'blocksub' (except main_frame)</h2>
+Given the following rule:
+<pre>
+  {
+    "id": 1,
+    "condition": {
+      "urlFilter": "blocksub"
+    },
+    "action": {
+      "type": "block"
+    }
+  },
+</pre>
+<div>
+  rule 1 will block this image (containing 'blocksub'):
+  <img src="https://developer.mozilla.org/favicon.ico?blocksub">
+</div>
+<div>
+  rule 1 will not block this image (does not contain 'blocksub'):
+  <img src="https://developer.mozilla.org/favicon.ico">
+</div>
+<div>
+  rule 1 will not block top-level navigations to
+  <a href="https://developer.mozilla.org/favicon.ico?blocksub">https://developer.mozilla.org/favicon.ico?blocksub</a>
+  because top-level navigation ("main_frame") requests are not matched
+  when "resourceTypes" and "excludedResourceTypes" are not specified.
+</div>
+
+<h2 id="blocktop">Block main_frame requests containing 'blocktop'</h2>
+Given the following rule:
+<pre>
+  {
+    "id": 2,
+    "condition": {
+      "urlFilter": "blocktop",
+      "resourceTypes": ["main_frame"]
+    },
+    "action": {
+      "type": "block"
+    }
+  },
+</pre>
+<div>
+  rule 2 will block top-level navigation to
+  <a href="https://developer.mozilla.org/favicon.ico?blocktop">https://developer.mozilla.org/favicon.ico?blocktop</a>
+  because the "resourceTypes" array contains "main_frame".
+</div>
+<div>
+  rule 2 will not block this image (containing 'blocktop')
+  <img src="https://developer.mozilla.org/favicon.ico?blocktop">
+  because "image" is not in the "resourceTypes" array.
+</div>
+
+<h2 id="blockall">Block all requests containing 'blockall'</h2>
+Given the following rule:
+<pre>
+  {
+    "id": 3,
+    "condition": {
+      "urlFilter": "blockall",
+      "excludedResourceTypes": []
+    },
+    "action": {
+      "type": "block"
+    }
+  }
+</pre>
+<div>
+  rule 3 will block this image (containing 'blockall'):
+  <img src="https://developer.mozilla.org/favicon.ico?blockall">
+</div>
+<div>
+  rule 3 will block top-level navigation to
+  <a href="https://developer.mozilla.org/favicon.ico?blockall">https://developer.mozilla.org/favicon.ico?blockall</a>
+  because "excludedResourceTypes" is set to an empty array.
+  <br>
+  Note: not blocked in Chrome due to <a href="https://crbug.com/1432871">https://crbug.com/1432871</a>.
+</div>
+
+</body>
+</html>
diff --git a/dnr-dynamic-with-options/README.md b/dnr-dynamic-with-options/README.md
@@ -0,0 +1,105 @@
+# dnr-dynamic-with-options
+
+Demonstrates a generic way to request host permissions and register
+declarativeNetRequest rules to modify network requests, without any
+install-time permission warnings. The `options_ui` page offers a way to request
+permissions and register declarative net request (DNR) rules.
+
+## What it does
+
+After loading the extension, visit the extension options page:
+
+1. Visit `about:addons`.
+2. Go to the extension at "DNR Dynamic with options".
+3. Click on Preferences to view its options page (options.html).
+
+On the options page:
+
+1. Input the list of host permissions and click on "Grant host permissions".
+2. Input the list of declarativeNetRequest rules and click "Save".
+3. Trigger a network request to verify that the rule matched.
+
+### Example for options page
+
+Host permissions:
+
+```json
+["*://example.com/"]
+```
+
+DNR rules:
+
+```json
+[
+  {
+    "id": 1,
+    "priority": 1,
+    "condition": {
+      "urlFilter": "|https://example.com/",
+      "resourceTypes": [
+        "main_frame"
+      ]
+    },
+    "action": {
+      "type": "block"
+    }
+  }
+]
+```
+
+Manual test case: Visit https://example.com/ and verify that it is blocked.
+
+# What it shows
+
+How to create an extension with no install-time permission warnings and 
+request (host) permissions as needed:
+
+- declares the "declarativeNetRequestWithHostAccess" permission, which
+  unlocks the declarativeNetRequest API without install-time warning.
+  In contrast, the "declarativeNetRequest" permission has the same effect,
+  but has the "Block content on any page" permission warning.
+- declares the most permissive match pattern in `optional_host_permissions`.
+- calls `permissions.request` to request host permissions.
+- uses `permissions.getAll` and `permissions.remove` to reset permissions.
+
+How to retrieve and dynamically register declarativeNetRequest rules, using:
+
+- `declarativeNetRequest.getDynamicRules` and
+  `declarativeNetRequest.updateDynamicRules` to manage DNR rules that persist
+  across extension restarts. These rules also persist across browser restarts,
+  unless the extension is loaded temporarily or unloaded.
+- `declarativeNetRequest.getSessionRules` and
+  `declarativeNetRequest.updateSessionRules` to manage DNR rules that are
+  session-scoped, that is, cleared when an extension unloads or the browser
+  quits.
+
+How these registered DNR rules can modify network requests without requiring an
+active extension script in the background, in a cross-browser way (at least in
+Firefox, Chrome, and Safari).
+
+## Note on `optional_host_permissions` and `optional_permissions`
+
+Firefox does not support `optional_host_permissions` permissions, it
+supports host permissions in `optional_permissions`
+(https://bugzilla.mozilla.org/show_bug.cgi?id=1766026).
+
+Chrome recognizes `optional_host_permissions` but does not support host
+permissions in `optional_permissions`.
+
+To support both, include `optional_host_permissions` and `optional_permissions`
+in your manifest.json.
+
+## Comparison with Manifest Version 2
+
+While this example uses `"manifest_version": 3`, the functionality is not
+specific to Manifest Version 3.
+
+To create a MV2 version of the extension, modify `manifest.json` as follows:
+
+- Set `manifest_version` to 2.
+- Use `optional_permissions` instead of `optional_host_permissions` to list
+  optional host permissions.
+  -  In this example, `optional_permissions` is present with
+     the same value as `optional_host_permissions` for the reasons explained in
+     the previous section. The latter is MV3-only and can be removed from a MV2
+     manifest.
diff --git a/dnr-dynamic-with-options/manifest.json b/dnr-dynamic-with-options/manifest.json
@@ -0,0 +1,12 @@
+{
+  "manifest_version": 3,
+  "name": "DNR dynamic with options",
+  "description": "Modify requests according to the rules specified by the user in the options page.",
+  "version": "0.1",
+  "permissions": ["declarativeNetRequestWithHostAccess"],
+  "optional_host_permissions": ["*://*/"],
+  "optional_permissions": ["*://*/"],
+  "options_ui": {
+    "page": "options.html"
+  }
+}
diff --git a/dnr-dynamic-with-options/options.css b/dnr-dynamic-with-options/options.css
@@ -0,0 +1,8 @@
+.input-and-buttons legend {
+  font-weight: bold;
+}
+.input-and-buttons textarea {
+  display: block;
+  width: 100%;
+  min-height: 7em;
+}
diff --git a/dnr-dynamic-with-options/options.html b/dnr-dynamic-with-options/options.html
@@ -0,0 +1,36 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width"> <!-- mobile-friendly -->
+<link rel="stylesheet" type="text/css" href="options.css">
+</head>
+<body>
+  <fieldset class="input-and-buttons">
+    <legend>Allowed host permissions</legend>
+    Specify the JSON-formatted list of allowed host permissions (documentation: <a href="https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/permissions/Permissions#origins">origins</a>).
+    <textarea id="input-host-permissions"></textarea>
+    <button id="grant-host-permissions">Grant host permissions</button>
+    <button id="reset-host-permissions">Reset host permissions</button>
+    <output id="status-host-permissions"></output>
+  </fieldset>
+
+  <fieldset class="input-and-buttons">
+    <legend>Dynamic declarativeNetRequest rules (persists across restarts)</legend>
+    Specify the JSON-formatted list of dynamic DNR rules (documentation: <a href="https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/declarativeNetRequest#rules">declarativeNetRequest rules</a>).
+    <textarea id="input-dynamic-rules"></textarea>
+    <button id="save-dynamic-rules">Save</button>
+    <output id="status-dynamic-rules"></output>
+  </fieldset>
+
+  <fieldset class="input-and-buttons">
+    <legend>Session-scoped declarativeNetRequest rules (cleared on extension unload/reload)</legend>
+    Specify the JSON-formatted list of session DNR rules (documentation: <a href="https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/declarativeNetRequest#rules">declarativeNetRequest rules</a>).
+    <textarea id="input-session-rules"></textarea>
+    <button id="save-session-rules">Save</button>
+    <output id="status-session-rules"></output>
+  </fieldset>
+
+  <script src="options.js"></script>
+</body>
+</html>