Bug 937820 - Create Snippets XPCOM component. r=bnicholson

mobile/android/app/mobile.js

@@ -788,3 +788,17 @@ pref("browser.ui.linkify.phone", false);
 
 // Enables/disables Spatial Navigation
 pref("snav.enabled", true);
+
+// This url, if changed, MUST continue to point to an https url. Pulling arbitrary content to inject into
+// this page over http opens us up to a man-in-the-middle attack that we'd rather not face. If you are a downstream
+// repackager of this code using an alternate snippet url, please keep your users safe
+pref("browser.snippets.updateUrl", "https://snippets.mozilla.com/json/%SNIPPETS_VERSION%/%NAME%/%VERSION%/%APPBUILDID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/");
+
+// How frequently we check for new snippets, in seconds (1 day)
+pref("browser.snippets.updateInterval", 86400);
+
+// URL used to check for user's country code
+pref("browser.snippets.geoUrl", "https://geo.mozilla.org/country.json");
+
+// This pref requires a restart to take effect.
+pref("browser.snippets.enabled", false);

mobile/android/components/MobileComponents.manifest

@@ -99,3 +99,9 @@ contract @mozilla.org/payment/ui-glue;1 {3c6c9575-f57e-427b-a8aa-57bc3cbff48f}
 # FilePicker.js
 component {18a4e042-7c7c-424b-a583-354e68553a7f} FilePicker.js
 contract @mozilla.org/filepicker;1 {18a4e042-7c7c-424b-a583-354e68553a7f}
+
+# Snippets.js
+component {a78d7e59-b558-4321-a3d6-dffe2f1e76dd} Snippets.js
+contract @mozilla.org/snippets;1 {a78d7e59-b558-4321-a3d6-dffe2f1e76dd}
+category profile-after-change Snippets @mozilla.org/snippets;1
+category update-timer Snippets @mozilla.org/snippets;1,getService,snippets-update-timer,browser.snippets.updateInterval,86400

mobile/android/components/Snippets.js

@@ -0,0 +1,233 @@
+/* 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 { classes: Cc, interfaces: Ci, utils: Cu } = Components;
+
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+
+XPCOMUtils.defineLazyModuleGetter(this, "Home", "resource://gre/modules/Home.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "OS", "resource://gre/modules/osfile.jsm");
+
+XPCOMUtils.defineLazyGetter(this, "gEncoder", function() { return new gChromeWin.TextEncoder(); });
+XPCOMUtils.defineLazyGetter(this, "gDecoder", function() { return new gChromeWin.TextDecoder(); });
+
+const SNIPPETS_ENABLED = Services.prefs.getBoolPref("browser.snippets.enabled");
+
+// URL to fetch snippets, in the urlFormatter service format.
+const SNIPPETS_UPDATE_URL_PREF = "browser.snippets.updateUrl";
+
+// URL to fetch country code, a value that's cached and refreshed once per month.
+const SNIPPETS_GEO_URL_PREF = "browser.snippets.geoUrl";
+
+// Timestamp when we last updated the user's country code.
+const SNIPPETS_GEO_LAST_UPDATE_PREF = "browser.snippets.geoLastUpdate";
+
+// Pref where we'll cache the user's country.
+const SNIPPETS_COUNTRY_CODE_PREF = "browser.snippets.countryCode";
+
+// How frequently we update the user's country code from the server (30 days).
+const SNIPPETS_GEO_UPDATE_INTERVAL_MS = 86400000*30;
+
+// Should be bumped up if the snippets content format changes.
+const SNIPPETS_VERSION = 1;
+
+XPCOMUtils.defineLazyGetter(this, "gSnippetsURL", function() {
+  let updateURL = Services.prefs.getCharPref(SNIPPETS_UPDATE_URL_PREF).replace("%SNIPPETS_VERSION%", SNIPPETS_VERSION);
+  return Services.urlFormatter.formatURL(updateURL);
+});
+
+XPCOMUtils.defineLazyGetter(this, "gGeoURL", function() {
+  return Services.prefs.getCharPref(SNIPPETS_GEO_URL_PREF);
+});
+
+XPCOMUtils.defineLazyGetter(this, "gCountryCode", function() {
+  try {
+    return Services.prefs.getCharPref(SNIPPETS_COUNTRY_CODE_PREF);
+  } catch (e) {
+    // Return an empty string if the country code pref isn't set yet.
+    return "";
+  }
+});
+
+XPCOMUtils.defineLazyGetter(this, "gChromeWin", function() {
+  return Services.wm.getMostRecentWindow("navigator:browser");
+});
+
+/**
+ * Updates snippet data and country code (if necessary).
+ */
+function update() {
+  // Check to see if we should update the user's country code from the geo server.
+  let lastUpdate = 0;
+  try {
+    lastUpdate = parseFloat(Services.prefs.getCharPref(SNIPPETS_GEO_LAST_UPDATE_PREF));
+  } catch (e) {}
+
+  if (Date.now() - lastUpdate > SNIPPETS_GEO_UPDATE_INTERVAL_MS) {
+    // We should update the snippets after updating the country code,
+    // so that we can filter snippets to add to the banner.
+    updateCountryCode(updateSnippets);
+  } else {
+    updateSnippets();
+  }
+}
+
+/**
+ * Fetches the user's country code from the geo server and stores the value in a pref.
+ *
+ * @param callback function called once country code is updated
+ */
+function updateCountryCode(callback) {
+  _httpGetRequest(gGeoURL, function(responseText) {
+    // Store the country code in a pref.
+    let data = JSON.parse(responseText);
+    Services.prefs.setCharPref(SNIPPETS_COUNTRY_CODE_PREF, data.country_code);
+
+    // Set last update time.
+    Services.prefs.setCharPref(SNIPPETS_GEO_LAST_UPDATE_PREF, Date.now());
+
+    callback();
+  });
+}
+
+/**
+ * Loads snippets from snippets server, caches the response, and
+ * updates the home banner with the new set of snippets.
+ */
+function updateSnippets() {
+  _httpGetRequest(gSnippetsURL, function(responseText) {
+    cacheSnippets(responseText);
+    updateBanner(responseText);
+  });
+}
+
+/**
+ * Caches snippets server response text to `snippets.json` in profile directory.
+ *
+ * @param response responseText returned from snippets server
+ */
+function cacheSnippets(response) {
+  let path = OS.Path.join(OS.Constants.Path.profileDir, "snippets.json");
+  let data = gEncoder.encode(response);
+  let promise = OS.File.writeAtomic(path, data, { tmpPath: path + ".tmp" });
+  promise.then(null, e => Cu.reportError("Error caching snippets: " + e));
+}
+
+/**
+ * Loads snippets from cached `snippets.json`.
+ */
+function loadSnippetsFromCache() {
+  let path = OS.Path.join(OS.Constants.Path.profileDir, "snippets.json");
+  let promise = OS.File.read(path);
+  promise.then(array => updateBanner(gDecoder.decode(array)), e => {
+    // If snippets.json doesn't exist, update data from the server.
+    if (e instanceof OS.File.Error && e.becauseNoSuchFile) {
+      update();
+    } else {
+      Cu.reportError("Error loading snippets from cache: " + e);
+    }
+  });
+}
+
+// Array of the message ids added to the home banner, used to remove
+// older set of snippets when new ones are available.
+var gMessageIds = [];
+
+/**
+ * Updates set of snippets in the home banner message rotation.
+ *
+ * @param response responseText returned from snippets server.
+ *   This should be a JSON array of message data JSON objects.
+ *   Each message object should have the following properties:
+ *     - id (?): Unique identifier for this snippets message
+ *     - text (string): Text to show as banner message
+ *     - url (string): URL to open when banner is clicked
+ *     - icon (data URI): Icon to appear in banner
+ *     - target_geo (string): Country code for where this message should be shown (e.g. "US")
+ */
+function updateBanner(response) {
+  // Remove the current messages, if there are any.
+  gMessageIds.forEach(function(id) {
+    Home.banner.remove(id);
+  })
+  gMessageIds = [];
+
+  let messages = JSON.parse(response);
+  messages.forEach(function(message) {
+    // Don't add this message to the banner if it's not supposed to be shown in this country.
+    if ("target_geo" in message && message.target_geo != gCountryCode) {
+      return;
+    }
+    let id = Home.banner.add({
+      text: message.text,
+      icon: message.icon,
+      onclick: function() {
+        gChromeWin.BrowserApp.addTab(message.url);
+      },
+      onshown: function() {
+        // XXX: 10% of the time, let the metrics server know which message was shown (bug 937373)
+      }
+    });
+    // Keep track of the message we added so that we can remove it later.
+    gMessageIds.push(id);
+  });
+}
+
+/**
+ * Helper function to make HTTP GET requests.
+ *
+ * @param url where we send the request
+ * @param callback function that is called with the xhr responseText
+ */
+function _httpGetRequest(url, callback) {
+  let xhr = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"].createInstance(Ci.nsIXMLHttpRequest);
+  try {
+    xhr.open("GET", url, true);
+  } catch (e) {
+    Cu.reportError("Error opening request to " + url + ": " + e);
+    return;
+  }
+  xhr.onerror = function onerror(e) {
+    Cu.reportError("Error making request to " + url + ": " + e.error);
+  }
+  xhr.onload = function onload(event) {
+    if (xhr.status !== 200) {
+      Cu.reportError("Request to " + url + " returned status " + xhr.status);
+      return;
+    }
+    if (callback) {
+      callback(xhr.responseText);
+    }
+  }
+  xhr.send(null);
+}
+
+function Snippets() {}
+
+Snippets.prototype = {
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver, Ci.nsITimerCallback]),
+  classID: Components.ID("{a78d7e59-b558-4321-a3d6-dffe2f1e76dd}"),
+
+  observe: function(subject, topic, data) {
+    if (!SNIPPETS_ENABLED) {
+      return;
+    }
+    switch(topic) {
+      case "profile-after-change":
+        loadSnippetsFromCache();
+        break;
+    }
+  },
+
+  // By default, this timer fires once every 24 hours. See the "browser.snippets.updateInterval" pref.
+  notify: function(timer) {
+    if (!SNIPPETS_ENABLED) {
+      return;
+    }
+    update();
+  }
+};
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([Snippets]);

mobile/android/components/moz.build

@@ -22,6 +22,7 @@ EXTRA_COMPONENTS += [
     'PaymentsUI.js',
     'PromptService.js',
     'SiteSpecificUserAgent.js',
+    'Snippets.js',
     'XPIDialogService.js',
 ]
 

mobile/android/installer/package-manifest.in

@@ -571,6 +571,7 @@ bin/components/@DLL_PREFIX@nkgnomevfs@DLL_SUFFIX@
 @BINPATH@/components/PromptService.js
 @BINPATH@/components/SessionStore.js
 @BINPATH@/components/Sidebar.js
+@BINPATH@/components/Snippets.js
 
 @BINPATH@/components/Payment.js
 @BINPATH@/components/PaymentFlowInfo.js