1 files changed, 168 insertions, 0 deletions
diff --git a/netwerk/url-classifier/UrlClassifierExceptionListService.sys.mjs b/netwerk/url-classifier/UrlClassifierExceptionListService.sys.mjs
new file mode 100644
index 0000000000..8c2bc8a3aa
--- /dev/null
+++ b/netwerk/url-classifier/UrlClassifierExceptionListService.sys.mjs
@@ -0,0 +1,168 @@
+/* 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/. */
+
+export function UrlClassifierExceptionListService() {}
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  RemoteSettings: "resource://services-settings/remote-settings.sys.mjs",
+});
+
+const COLLECTION_NAME = "url-classifier-skip-urls";
+
+class Feature {
+  constructor(name, prefName) {
+    this.name = name;
+    this.prefName = prefName;
+    this.observers = new Set();
+    this.prefValue = null;
+    this.remoteEntries = null;
+
+    if (prefName) {
+      this.prefValue = Services.prefs.getStringPref(this.prefName, null);
+      Services.prefs.addObserver(prefName, this);
+    }
+  }
+
+  async addAndRunObserver(observer) {
+    this.observers.add(observer);
+    this.notifyObservers(observer);
+  }
+
+  removeObserver(observer) {
+    this.observers.delete(observer);
+  }
+
+  observe(subject, topic, data) {
+    if (topic != "nsPref:changed" || data != this.prefName) {
+      console.error(`Unexpected event ${topic} with ${data}`);
+      return;
+    }
+
+    this.prefValue = Services.prefs.getStringPref(this.prefName, null);
+    this.notifyObservers();
+  }
+
+  onRemoteSettingsUpdate(entries) {
+    this.remoteEntries = [];
+
+    for (let entry of entries) {
+      if (entry.feature == this.name) {
+        this.remoteEntries.push(entry.pattern.toLowerCase());
+      }
+    }
+  }
+
+  notifyObservers(observer = null) {
+    let entries = [];
+    if (this.prefValue) {
+      entries = this.prefValue.split(",");
+    }
+
+    if (this.remoteEntries) {
+      for (let entry of this.remoteEntries) {
+        entries.push(entry);
+      }
+    }
+
+    let entriesAsString = entries.join(",").toLowerCase();
+    if (observer) {
+      observer.onExceptionListUpdate(entriesAsString);
+    } else {
+      for (let obs of this.observers) {
+        obs.onExceptionListUpdate(entriesAsString);
+      }
+    }
+  }
+}
+
+UrlClassifierExceptionListService.prototype = {
+  classID: Components.ID("{b9f4fd03-9d87-4bfd-9958-85a821750ddc}"),
+  QueryInterface: ChromeUtils.generateQI([
+    "nsIUrlClassifierExceptionListService",
+  ]),
+
+  features: {},
+  _initialized: false,
+
+  async lazyInit() {
+    if (this._initialized) {
+      return;
+    }
+
+    let rs = lazy.RemoteSettings(COLLECTION_NAME);
+    rs.on("sync", event => {
+      let {
+        data: { current },
+      } = event;
+      this.entries = current || [];
+      this.onUpdateEntries(current);
+    });
+
+    this._initialized = true;
+
+    // If the remote settings list hasn't been populated yet we have to make sure
+    // to do it before firing the first notification.
+    // This has to be run after _initialized is set because we'll be
+    // blocked while getting entries from RemoteSetting, and we don't want
+    // LazyInit is executed again.
+    try {
+      // The data will be initially available from the local DB (via a
+      // resource:// URI).
+      this.entries = await rs.get();
+    } catch (e) {}
+
+    // RemoteSettings.get() could return null, ensure passing a list to
+    // onUpdateEntries.
+    if (!this.entries) {
+      this.entries = [];
+    }
+
+    this.onUpdateEntries(this.entries);
+  },
+
+  onUpdateEntries(entries) {
+    for (let key of Object.keys(this.features)) {
+      let feature = this.features[key];
+      feature.onRemoteSettingsUpdate(entries);
+      feature.notifyObservers();
+    }
+  },
+
+  registerAndRunExceptionListObserver(feature, prefName, observer) {
+    // We don't await this; the caller is C++ and won't await this function,
+    // and because we prevent re-entering into this method, once it's been
+    // called once any subsequent calls will early-return anyway - so
+    // awaiting that would be meaningless. Instead, `Feature` implementations
+    // make sure not to call into observers until they have data, and we
+    // make sure to let feature instances know whether we have data
+    // immediately.
+    this.lazyInit();
+
+    if (!this.features[feature]) {
+      let featureObj = new Feature(feature, prefName);
+      this.features[feature] = featureObj;
+      // If we've previously initialized, we need to pass the entries
+      // we already have to the new feature.
+      if (this.entries) {
+        featureObj.onRemoteSettingsUpdate(this.entries);
+      }
+    }
+    this.features[feature].addAndRunObserver(observer);
+  },
+
+  unregisterExceptionListObserver(feature, observer) {
+    if (!this.features[feature]) {
+      return;
+    }
+    this.features[feature].removeObserver(observer);
+  },
+
+  clear() {
+    this.features = {};
+    this._initialized = false;
+    this.entries = null;
+  },
+};