firefox/toolkit/components/url-classifier/UrlClassifierListManager.sys.mjs

/* 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/. */

import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";

// This is the only implementation of nsIUrlListManager.
// A class that manages lists, namely exception and block lists for
// phishing or malware protection. The ListManager knows how to fetch,
// update, and store lists.
//
// There is a single listmanager for the whole application.
//
// TODO more comprehensive update tests, for example add unittest check
//      that the listmanagers tables are properly written on updates

// Lower and upper limits on the server-provided polling frequency
const minDelayMs = 5 * 60 * 1000;
const maxDelayMs = 24 * 60 * 60 * 1000;
const defaultUpdateIntervalMs = 30 * 60 * 1000;
// The threshold to check if the browser is idle. We will defer the update in
// order to save the power consumption if the browser has been idle for one hour
// because it's likely that the browser will keep idle for a longer period.
const browserIdleThresholdMs = 60 * 60 * 1000;
const PREF_DEBUG_ENABLED = "browser.safebrowsing.debug";
const PREF_TEST_NOTIFICATIONS =
  "browser.safebrowsing.test-notifications.enabled";

let loggingEnabled = false;

// Variables imported from library.
let BindToObject, RequestBackoffV4;

// Log only if browser.safebrowsing.debug is true
function log(...stuff) {
  if (!loggingEnabled) {
    return;
  }

  var d = new Date();
  let msg = "listmanager: " + d.toTimeString() + ": " + stuff.join(" ");
  msg = Services.urlFormatter.trimSensitiveURLs(msg);
  Services.console.logStringMessage(msg);
  dump(msg + "\n");
}

/**
 * A ListManager keeps track of exception and block lists and knows
 * how to update them.
 *
 * @constructor
 */
function PROT_ListManager() {
  loggingEnabled = Services.prefs.getBoolPref(PREF_DEBUG_ENABLED);

  log("Initializing list manager");

  // A map of tableNames to objects of type
  // { updateUrl: <updateUrl>, gethashUrl: <gethashUrl> }
  this.tablesData = {};
  // A map of updateUrls to maps of tables requiring updates, e.g.
  // { safebrowsing-update-url: { goog-phish-shavar: true,
  //                              goog-malware-shavar: true }
  this.needsUpdate_ = {};

  // A map of updateUrls to single-use nsITimer. An entry exists if and only if
  // there is at least one table with updates enabled for that url. nsITimers
  // are reset when enabling/disabling updates or on update callbacks (update
  // success, update failure, download error).
  this.updateCheckers_ = {};
  this.requestBackoffs_ = {};

  // This is only used by testcases to ensure SafeBrowsing.sys.mjs is inited
  this.registered = false;

  this.dbService_ = Cc["@mozilla.org/url-classifier/dbservice;1"].getService(
    Ci.nsIUrlClassifierDBService
  );

  this.idleService_ = Cc["@mozilla.org/widget/useridleservice;1"].getService(
    Ci.nsIUserIdleService
  );

  Services.obs.addObserver(this, "quit-application");
  Services.prefs.addObserver(PREF_DEBUG_ENABLED, this);
}

/**
 * Register a new table table
 * @param tableName - the name of the table
 * @param updateUrl - the url for updating the table
 * @param gethashUrl - the url for fetching hash completions
 * @returns true if the table could be created; false otherwise
 */
PROT_ListManager.prototype.registerTable = function (
  tableName,
  providerName,
  updateUrl,
  gethashUrl
) {
  this.registered = true;

  this.tablesData[tableName] = {};
  if (!updateUrl) {
    log("Can't register table " + tableName + " without updateUrl");
    return false;
  }
  log("registering " + tableName + " with " + updateUrl);
  this.tablesData[tableName].updateUrl = updateUrl;
  this.tablesData[tableName].gethashUrl = gethashUrl;
  this.tablesData[tableName].provider = providerName;

  // Keep track of all of our update URLs.
  if (!this.needsUpdate_[updateUrl]) {
    this.needsUpdate_[updateUrl] = {};

    // Using the V4 backoff algorithm for both V2 and V4. See bug 1273398.
    this.requestBackoffs_[updateUrl] = new RequestBackoffV4(
      4 /* num requests */,
      60 * 60 * 1000 /* request time, 60 min */,
      providerName /* used by testcase */
    );
  }
  this.needsUpdate_[updateUrl][tableName] = false;

  return true;
};

/**
 * Unregister a table table from list
 */
PROT_ListManager.prototype.unregisterTable = function (tableName) {
  log("unregistering " + tableName);
  var table = this.tablesData[tableName];
  if (table) {
    if (
      !this.updatesNeeded_(table.updateUrl) &&
      this.updateCheckers_[table.updateUrl]
    ) {
      this.updateCheckers_[table.updateUrl].cancel();
      this.updateCheckers_[table.updateUrl] = null;
    }
    delete this.needsUpdate_[table.updateUrl][tableName];
  }
  delete this.tablesData[tableName];
};

/**
 * Delete all of our data tables which seem to leak otherwise.
 * Remove observers
 */
PROT_ListManager.prototype.shutdown_ = function () {
  this.stopUpdateCheckers();
  for (var name in this.tablesData) {
    delete this.tablesData[name];
  }
  Services.obs.removeObserver(this, "quit-application");
  Services.prefs.removeObserver(PREF_DEBUG_ENABLED, this);
};

/**
 * xpcom-shutdown callback
 */
PROT_ListManager.prototype.observe = function (aSubject, aTopic, aData) {
  switch (aTopic) {
    case "quit-application":
      this.shutdown_();
      break;
    case "nsPref:changed":
      if (aData == PREF_DEBUG_ENABLED) {
        loggingEnabled = Services.prefs.getBoolPref(PREF_DEBUG_ENABLED);
      }
      break;
  }
};

PROT_ListManager.prototype.getGethashUrl = function (tableName) {
  if (this.tablesData[tableName] && this.tablesData[tableName].gethashUrl) {
    return this.tablesData[tableName].gethashUrl;
  }
  return "";
};

PROT_ListManager.prototype.getUpdateUrl = function (tableName) {
  if (this.tablesData[tableName] && this.tablesData[tableName].updateUrl) {
    return this.tablesData[tableName].updateUrl;
  }
  return "";
};

/**
 * Enable updates for a single table.
 */
PROT_ListManager.prototype.enableUpdate = function (tableName) {
  var table = this.tablesData[tableName];
  if (table) {
    log("Enabling table updates for " + tableName);
    this.needsUpdate_[table.updateUrl][tableName] = true;
  }
};

PROT_ListManager.prototype.isRegistered = function () {
  return this.registered;
};

/**
 * Returns true if any table associated with the updateUrl requires updates.
 * @param updateUrl - the updateUrl
 */
PROT_ListManager.prototype.updatesNeeded_ = function (updateUrl) {
  let updatesNeeded = false;
  for (var tableName in this.needsUpdate_[updateUrl]) {
    if (this.needsUpdate_[updateUrl][tableName]) {
      updatesNeeded = true;
    }
  }
  return updatesNeeded;
};

/**
 * Disable updates for all tables.
 */
PROT_ListManager.prototype.disableAllUpdates = function () {
  for (const tableName of Object.keys(this.tablesData)) {
    this.disableUpdate(tableName);
  }
};

/**
 * Disables updates for a single table. Avoid this internal function
 * and use disableAllUpdates() instead.
 */
PROT_ListManager.prototype.disableUpdate = function (tableName) {
  var table = this.tablesData[tableName];
  if (table) {
    log("Disabling table updates for " + tableName);
    this.needsUpdate_[table.updateUrl][tableName] = false;
    if (
      !this.updatesNeeded_(table.updateUrl) &&
      this.updateCheckers_[table.updateUrl]
    ) {
      this.updateCheckers_[table.updateUrl].cancel();
      this.updateCheckers_[table.updateUrl] = null;
    }
  }
};

/**
 * Determine if we have some tables that need updating.
 */
PROT_ListManager.prototype.requireTableUpdates = function () {
  for (var name in this.tablesData) {
    // Tables that need updating even if other tables don't require it
    if (this.needsUpdate_[this.tablesData[name].updateUrl][name]) {
      return true;
    }
  }

  return false;
};

/**
 *  Set timer to check update after delay
 */
PROT_ListManager.prototype.setUpdateCheckTimer = function (updateUrl, delay) {
  this.updateCheckers_[updateUrl] = Cc["@mozilla.org/timer;1"].createInstance(
    Ci.nsITimer
  );

  // A helper function to trigger the table update.
  let update = function () {
    if (!this.checkForUpdates(updateUrl)) {
      // Make another attempt later.
      this.setUpdateCheckTimer(updateUrl, defaultUpdateIntervalMs);
    }
  }.bind(this);

  this.updateCheckers_[updateUrl].initWithCallback(
    () => {
      this.updateCheckers_[updateUrl] = null;
      // Check if we are in the idle mode. We will stop the current update and
      // defer it to the next user interaction active if the browser is
      // considered in idle mode.
      if (this.idleService_.idleTime > browserIdleThresholdMs) {
        let observer = function () {
          Services.obs.removeObserver(observer, "user-interaction-active");
          update();
        };

        Services.obs.addObserver(observer, "user-interaction-active");
        return;
      }

      update();
    },
    delay,
    Ci.nsITimer.TYPE_ONE_SHOT
  );
};
/**
 * Acts as a nsIUrlClassifierCallback for getTables.
 */
PROT_ListManager.prototype.kickoffUpdate_ = function () {
  this.startingUpdate_ = false;
  var initialUpdateDelay = 3000;
  // Add a fuzz of 0-1 minutes for both v2 and v4 according to Bug 1305478.
  initialUpdateDelay += Math.floor(Math.random() * (1 * 60 * 1000));

  // If the user has never downloaded tables, do the check now.
  log("needsUpdate: " + JSON.stringify(this.needsUpdate_, undefined, 2));
  for (var updateUrl in this.needsUpdate_) {
    // If we haven't already kicked off updates for this updateUrl, set a
    // non-repeating timer for it. The timer delay will be reset either on
    // updateSuccess to the default update interval, or backed off on
    // downloadError. Don't set the updateChecker unless at least one table has
    // updates enabled.
    if (this.updatesNeeded_(updateUrl) && !this.updateCheckers_[updateUrl]) {
      let provider = null;
      Object.keys(this.tablesData).forEach(function (table) {
        if (this.tablesData[table].updateUrl === updateUrl) {
          let newProvider = this.tablesData[table].provider;
          if (provider) {
            if (newProvider !== provider) {
              log(
                "Multiple tables for the same updateURL have a different provider?!"
              );
            }
          } else {
            provider = newProvider;
          }
        }
      }, this);
      log(
        "Initializing update checker for " +
          updateUrl +
          " provided by " +
          provider
      );

      // Use the initialUpdateDelay + fuzz unless we had previous updates
      // and the server told us when to try again.
      let updateDelay = initialUpdateDelay;
      let nextUpdatePref =
        "browser.safebrowsing.provider." + provider + ".nextupdatetime";
      let nextUpdate = Services.prefs.getCharPref(nextUpdatePref, "");

      if (nextUpdate) {
        updateDelay = Math.min(
          maxDelayMs,
          Math.max(0, nextUpdate - Date.now())
        );
        log("Next update at " + nextUpdate);
      }
      log("Next update " + Math.round(updateDelay / 60000) + "min from now");

      this.setUpdateCheckTimer(updateUrl, updateDelay);
    } else {
      log("No updates needed or already initialized for " + updateUrl);
    }
  }
};

PROT_ListManager.prototype.stopUpdateCheckers = function () {
  log("Stopping updates");
  for (var updateUrl in this.updateCheckers_) {
    if (this.updateCheckers_[updateUrl]) {
      this.updateCheckers_[updateUrl].cancel();
      this.updateCheckers_[updateUrl] = null;
    }
  }
};

/**
 * Determine if we have any tables that require updating.  Different
 * Wardens may call us with new tables that need to be updated.
 */
PROT_ListManager.prototype.maybeToggleUpdateChecking = function () {
  // We update tables if we have some tables that want updates.  If there
  // are no tables that want to be updated - we dont need to check anything.
  if (this.requireTableUpdates()) {
    log("Starting managing lists");

    // Get the list of existing tables from the DBService before making any
    // update requests.
    if (!this.startingUpdate_) {
      this.startingUpdate_ = true;
      // check the current state of tables in the database
      this.kickoffUpdate_();
    }
  } else {
    log("Stopping managing lists (if currently active)");
    this.stopUpdateCheckers(); // Cancel pending updates
  }
};

/**
 * Force updates for the given tables. This API may trigger more than one update
 * if the table lists provided belong to multiple updateurl (multiple provider).
 * Return false when any update is fail due to back-off algorithm.
 */
PROT_ListManager.prototype.forceUpdates = function (tables) {
  log("forceUpdates with " + tables);
  if (!tables) {
    return false;
  }

  let updateUrls = new Set();
  tables.split(",").forEach(table => {
    if (this.tablesData[table]) {
      updateUrls.add(this.tablesData[table].updateUrl);
    }
  });

  let ret = true;

  updateUrls.forEach(url => {
    // Cancel current update timer for the url because we are forcing an update.
    if (this.updateCheckers_[url]) {
      this.updateCheckers_[url].cancel();
      this.updateCheckers_[url] = null;
    }

    // Trigger an update for the given url.
    if (!this.checkForUpdates(url, true)) {
      ret = false;
    }
  });

  return ret;
};

/**
 * Updates our internal tables from the update server
 *
 * @param updateUrl: request updates for tables associated with that url, or
 * for all tables if the url is empty.
 * @param manual: the update is triggered manually
 */
PROT_ListManager.prototype.checkForUpdates = function (
  updateUrl,
  manual = false
) {
  log("checkForUpdates with " + updateUrl);
  // See if we've triggered the request backoff logic.
  if (!updateUrl) {
    return false;
  }

  // Disable SafeBrowsing updates in Safe Mode, but still allow manually
  // triggering an update for debugging.
  if (Services.appinfo.inSafeMode && !manual) {
    log("update is disabled in Safe Mode");
    return false;
  }

  if (lazy.enableTestNotifications) {
    Services.obs.notifyObservers(
      null,
      "safebrowsing-update-attempt",
      updateUrl
    );
  }

  if (
    !this.requestBackoffs_[updateUrl] ||
    !this.requestBackoffs_[updateUrl].canMakeRequest()
  ) {
    log("Can't make update request");
    return false;
  }
  // Grab the current state of the tables from the database
  this.dbService_.getTables(
    BindToObject(this.makeUpdateRequest_, this, updateUrl)
  );
  return true;
};

/**
 * Method that fires the actual HTTP update request.
 * First we reset any tables that have disappeared.
 * @param tableData List of table data already in the database, in the form
 *        tablename;<chunk ranges>\n
 */
PROT_ListManager.prototype.makeUpdateRequest_ = function (
  updateUrl,
  tableData
) {
  log("this.tablesData: " + JSON.stringify(this.tablesData, undefined, 2));
  log("existing chunks: " + tableData + "\n");
  // Disallow blank updateUrls
  if (!updateUrl) {
    return;
  }
  // An object of the form
  // { tableList: comma-separated list of tables to request,
  //   tableNames: map of tables that need updating,
  //   request: list of tables and existing chunk ranges from tableData
  // }
  var streamerMap = {
    tableList: null,
    tableNames: {},
    requestPayload: "",
    isPostRequest: true,
  };

  let useProtobuf = false;
  let onceThru = false;
  for (var tableName in this.tablesData) {
    // Skip tables not matching this update url
    if (this.tablesData[tableName].updateUrl != updateUrl) {
      continue;
    }

    // Check if |updateURL| is for 'proto'. (only v4 uses protobuf for now.)
    // We use the table name 'goog-*-proto' and an additional provider "google4"
    // to describe the v4 settings.
    let isCurTableProto = tableName.endsWith("-proto");
    if (!onceThru) {
      useProtobuf = isCurTableProto;
      onceThru = true;
    } else if (useProtobuf !== isCurTableProto) {
      log(
        'ERROR: Cannot mix "proto" tables with other types ' +
          "within the same provider."
      );
    }

    if (this.needsUpdate_[this.tablesData[tableName].updateUrl][tableName]) {
      streamerMap.tableNames[tableName] = true;
    }
    if (!streamerMap.tableList) {
      streamerMap.tableList = tableName;
    } else {
      streamerMap.tableList += "," + tableName;
    }
  }

  if (useProtobuf) {
    let tableArray = [];
    Object.keys(streamerMap.tableNames).forEach(aTableName => {
      if (streamerMap.tableNames[aTableName]) {
        tableArray.push(aTableName);
      }
    });

    // Build the <tablename, stateBase64> mapping.
    let tableState = {};
    tableData.split("\n").forEach(line => {
      let p = line.indexOf(";");
      if (-1 === p) {
        return;
      }
      let tableName = line.substring(0, p);
      if (tableName in streamerMap.tableNames) {
        let metadata = line.substring(p + 1).split(":");
        let stateBase64 = metadata[0];
        log(tableName + " ==> " + stateBase64);
        tableState[tableName] = stateBase64;
      }
    });

    // The state is a byte stream which server told us from the
    // last table update. The state would be used to do the partial
    // update and the empty string means the table has
    // never been downloaded. See Bug 1287058 for supporting
    // partial update.
    let stateArray = [];
    tableArray.forEach(listName => {
      stateArray.push(tableState[listName] || "");
    });

    log("stateArray: " + stateArray);

    let urlUtils = Cc["@mozilla.org/url-classifier/utils;1"].getService(
      Ci.nsIUrlClassifierUtils
    );

    streamerMap.requestPayload = urlUtils.makeUpdateRequestV4(
      tableArray,
      stateArray
    );
    streamerMap.isPostRequest = false;
  } else {
    // Build the request. For each table already in the database, include the
    // chunk data from the database
    var lines = tableData.split("\n");
    for (var i = 0; i < lines.length; i++) {
      var fields = lines[i].split(";");
      var name = fields[0];
      if (streamerMap.tableNames[name]) {
        streamerMap.requestPayload += lines[i] + "\n";
        delete streamerMap.tableNames[name];
      }
    }
    // For each requested table that didn't have chunk data in the database,
    // request it fresh
    for (let tableName in streamerMap.tableNames) {
      streamerMap.requestPayload += tableName + ";\n";
    }

    streamerMap.isPostRequest = true;
  }

  log("update request: " + JSON.stringify(streamerMap, undefined, 2) + "\n");

  // Don't send an empty request.
  if (streamerMap.requestPayload.length) {
    this.makeUpdateRequestForEntry_(
      updateUrl,
      streamerMap.tableList,
      streamerMap.requestPayload,
      streamerMap.isPostRequest
    );
  } else {
    // We were disabled between kicking off getTables and now.
    log("Not sending empty request");
  }
};

PROT_ListManager.prototype.makeUpdateRequestForEntry_ = function (
  updateUrl,
  tableList,
  requestPayload,
  isPostRequest
) {
  log(
    "makeUpdateRequestForEntry_: requestPayload " +
      requestPayload +
      " update: " +
      updateUrl +
      " tablelist: " +
      tableList +
      "\n"
  );
  var streamer = Cc["@mozilla.org/url-classifier/streamupdater;1"].getService(
    Ci.nsIUrlClassifierStreamUpdater
  );

  this.requestBackoffs_[updateUrl].noteRequest();

  if (
    !streamer.downloadUpdates(
      tableList,
      requestPayload,
      isPostRequest,
      updateUrl,
      BindToObject(this.updateSuccess_, this, tableList, updateUrl),
      BindToObject(this.updateError_, this, tableList, updateUrl),
      BindToObject(this.downloadError_, this, tableList, updateUrl)
    )
  ) {
    // Our alarm gets reset in one of the 3 callbacks.
    log("pending update, queued request until later");
  } else {
    let table = Object.keys(this.tablesData).find(key => {
      return this.tablesData[key].updateUrl === updateUrl;
    });
    let provider = this.tablesData[table].provider;
    Services.obs.notifyObservers(null, "safebrowsing-update-begin", provider);
  }
};

/**
 * Callback function if the update request succeeded.
 * @param waitForUpdate String The number of seconds that the client should
 *        wait before requesting again.
 */
PROT_ListManager.prototype.updateSuccess_ = function (
  tableList,
  updateUrl,
  waitForUpdateSec
) {
  log(
    "update success for " +
      tableList +
      " from " +
      updateUrl +
      ": " +
      waitForUpdateSec +
      "\n"
  );

  // The time unit below are all milliseconds if not specified.

  var delay = 0;
  if (waitForUpdateSec) {
    delay = parseInt(waitForUpdateSec, 10) * 1000;
  }
  // As long as the delay is something sane (5 min to 1 day), update
  // our delay time for requesting updates. We always use a non-repeating
  // timer since the delay is set differently at every callback.
  if (delay > maxDelayMs) {
    log(
      "Ignoring delay from server (too long), waiting " +
        Math.round(maxDelayMs / 60000) +
        "min"
    );
    delay = maxDelayMs;
  } else if (delay < minDelayMs) {
    log(
      "Ignoring delay from server (too short), waiting " +
        Math.round(defaultUpdateIntervalMs / 60000) +
        "min"
    );
    delay = defaultUpdateIntervalMs;
  } else {
    log("Waiting " + Math.round(delay / 60000) + "min");
  }

  this.setUpdateCheckTimer(updateUrl, delay);

  // Let the backoff object know that we completed successfully.
  this.requestBackoffs_[updateUrl].noteServerResponse(200);

  // Set last update time for provider
  // Get the provider for these tables, check for consistency
  let tables = tableList.split(",");
  let provider = null;
  for (let table of tables) {
    let newProvider = this.tablesData[table].provider;
    if (provider) {
      if (newProvider !== provider) {
        log(
          "Multiple tables for the same updateURL have a different provider?!"
        );
      }
    } else {
      provider = newProvider;
    }
  }

  // Store the last update time (needed to know if the table is "fresh")
  // and the next update time (to know when to update next).
  let lastUpdatePref =
    "browser.safebrowsing.provider." + provider + ".lastupdatetime";
  let now = Date.now();
  log("Setting last update of " + provider + " to " + now);
  Services.prefs.setCharPref(lastUpdatePref, now.toString());

  let nextUpdatePref =
    "browser.safebrowsing.provider." + provider + ".nextupdatetime";
  let targetTime = now + delay;
  log(
    "Setting next update of " +
      provider +
      " to " +
      targetTime +
      " (" +
      Math.round(delay / 60000) +
      "min from now)"
  );
  Services.prefs.setCharPref(nextUpdatePref, targetTime.toString());

  Services.obs.notifyObservers(null, "safebrowsing-update-finished", "success");
};

/**
 * Callback function if the update request succeeded.
 * @param result String The error code of the failure
 */
PROT_ListManager.prototype.updateError_ = function (table, updateUrl, result) {
  log(
    "update error for " + table + " from " + updateUrl + ": " + result + "\n"
  );
  // There was some trouble applying the updates. Don't try again for at least
  // updateInterval milliseconds.
  this.setUpdateCheckTimer(updateUrl, defaultUpdateIntervalMs);

  Services.obs.notifyObservers(
    null,
    "safebrowsing-update-finished",
    "update error: " + result
  );
};

/**
 * Callback function when the download failed
 * @param status String http status or an empty string if connection refused.
 */
PROT_ListManager.prototype.downloadError_ = function (
  table,
  updateUrl,
  status
) {
  log("download error for " + table + ": " + status + "\n");
  // If status is empty, then we assume that we got an NS_CONNECTION_REFUSED
  // error.  In this case, we treat this is a http 500 error.
  if (!status) {
    status = 500;
  }
  status = parseInt(status, 10);
  this.requestBackoffs_[updateUrl].noteServerResponse(status);
  let delay = defaultUpdateIntervalMs;
  if (this.requestBackoffs_[updateUrl].isErrorStatus(status)) {
    // Schedule an update for when our backoff is complete
    delay = this.requestBackoffs_[updateUrl].nextRequestDelay();
  } else {
    log("Got non error status for error callback?!");
  }

  this.setUpdateCheckTimer(updateUrl, delay);

  Services.obs.notifyObservers(
    null,
    "safebrowsing-update-finished",
    "download error: " + status
  );
};

/**
 * Get back-off time for the given provider.
 * Return 0 if we are not in back-off mode.
 */
PROT_ListManager.prototype.getBackOffTime = function (provider) {
  let updateUrl = "";
  for (var table in this.tablesData) {
    if (this.tablesData[table].provider == provider) {
      updateUrl = this.tablesData[table].updateUrl;
      break;
    }
  }

  if (!updateUrl || !this.requestBackoffs_[updateUrl]) {
    return 0;
  }

  let delay = this.requestBackoffs_[updateUrl].nextRequestDelay();
  return delay == 0 ? 0 : Date.now() + delay;
};

PROT_ListManager.prototype.QueryInterface = ChromeUtils.generateQI([
  "nsIUrlListManager",
  "nsIObserver",
  "nsITimerCallback",
]);

let initialized = false;
function Init() {
  if (initialized) {
    return;
  }

  // Pull the library in.
  var jslib =
    Cc["@mozilla.org/url-classifier/jslib;1"].getService().wrappedJSObject;
  BindToObject = jslib.BindToObject;
  RequestBackoffV4 = jslib.RequestBackoffV4;

  initialized = true;
}

export function RegistrationData() {
  Init();
  return new PROT_ListManager();
}

const lazy = {};

XPCOMUtils.defineLazyPreferenceGetter(
  lazy,
  "enableTestNotifications",
  PREF_TEST_NOTIFICATIONS,
  false
);