1 files changed, 93 insertions, 0 deletions
diff --git a/toolkit/modules/IgnoreLists.sys.mjs b/toolkit/modules/IgnoreLists.sys.mjs
new file mode 100644
index 0000000000..1b7282d77f
--- /dev/null
+++ b/toolkit/modules/IgnoreLists.sys.mjs
@@ -0,0 +1,93 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  RemoteSettings: "resource://services-settings/remote-settings.sys.mjs",
+  RemoteSettingsClient:
+    "resource://services-settings/RemoteSettingsClient.sys.mjs",
+});
+
+const SETTINGS_IGNORELIST_KEY = "hijack-blocklists";
+
+class IgnoreListsManager {
+  async init() {
+    if (!this._ignoreListSettings) {
+      this._ignoreListSettings = lazy.RemoteSettings(SETTINGS_IGNORELIST_KEY);
+    }
+  }
+
+  async getAndSubscribe(listener) {
+    await this.init();
+
+    // Trigger a get of the initial value.
+    const settings = await this._getIgnoreList();
+
+    // Listen for future updates after we first get the values.
+    this._ignoreListSettings.on("sync", listener);
+
+    return settings;
+  }
+
+  unsubscribe(listener) {
+    if (!this._ignoreListSettings) {
+      return;
+    }
+
+    this._ignoreListSettings.off("sync", listener);
+  }
+
+  async _getIgnoreList() {
+    if (this._getSettingsPromise) {
+      return this._getSettingsPromise;
+    }
+
+    const settings = await (this._getSettingsPromise =
+      this._getIgnoreListSettings());
+    delete this._getSettingsPromise;
+    return settings;
+  }
+
+  /**
+   * Obtains the current ignore list from remote settings. This includes
+   * verifying the signature of the ignore list within the database.
+   *
+   * If the signature in the database is invalid, the database will be wiped
+   * and the stored dump will be used, until the settings next update.
+   *
+   * Note that this may cause a network check of the certificate, but that
+   * should generally be quick.
+   *
+   * @param {boolean} [firstTime]
+   *   Internal boolean to indicate if this is the first time check or not.
+   * @returns {array}
+   *   An array of objects in the database, or an empty array if none
+   *   could be obtained.
+   */
+  async _getIgnoreListSettings(firstTime = true) {
+    let result = [];
+    try {
+      result = await this._ignoreListSettings.get({
+        verifySignature: true,
+      });
+    } catch (ex) {
+      if (
+        ex instanceof lazy.RemoteSettingsClient.InvalidSignatureError &&
+        firstTime
+      ) {
+        // The local database is invalid, try and reset it.
+        await this._ignoreListSettings.db.clear();
+        // Now call this again.
+        return this._getIgnoreListSettings(false);
+      }
+      // Don't throw an error just log it, just continue with no data, and hopefully
+      // a sync will fix things later on.
+      console.error(ex);
+    }
+    return result;
+  }
+}
+
+export const IgnoreLists = new IgnoreListsManager();