michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: "use strict";
michael@0: 
michael@0: let Ci = Components.interfaces;
michael@0: let Cu = Components.utils;
michael@0: let Cr = Components.results;
michael@0: 
michael@0: Cu.import("resource://gre/modules/XPCOMUtils.jsm", this);
michael@0: Cu.import("resource://gre/modules/Services.jsm", this);
michael@0: 
michael@0: this.EXPORTED_SYMBOLS = ["ThirdPartyCookieProbe"];
michael@0: 
michael@0: const MILLISECONDS_PER_DAY = 1000 * 60 * 60 * 24;
michael@0: 
michael@0: /**
michael@0:  * A probe implementing the measurements detailed at
michael@0:  * https://wiki.mozilla.org/SecurityEngineering/ThirdPartyCookies/Telemetry
michael@0:  *
michael@0:  * This implementation uses only in-memory data.
michael@0:  */
michael@0: this.ThirdPartyCookieProbe = function() {
michael@0:   /**
michael@0:    * A set of third-party sites that have caused cookies to be
michael@0:    * rejected. These sites are trimmed down to ETLD + 1
michael@0:    * (i.e. "x.y.com" and "z.y.com" are both trimmed down to "y.com",
michael@0:    * "x.y.co.uk" is trimmed down to "y.co.uk").
michael@0:    *
michael@0:    * Used to answer the following question: "For each third-party
michael@0:    * site, how many other first parties embed them and result in
michael@0:    * cookie traffic?" (see
michael@0:    * https://wiki.mozilla.org/SecurityEngineering/ThirdPartyCookies/Telemetry#Breadth
michael@0:    * )
michael@0:    *
michael@0:    * @type Map<string, RejectStats> A mapping from third-party site
michael@0:    * to rejection statistics.
michael@0:    */
michael@0:   this._thirdPartyCookies = new Map();
michael@0:   /**
michael@0:    * Timestamp of the latest call to flush() in milliseconds since the Epoch.
michael@0:    */
michael@0:   this._latestFlush = Date.now();
michael@0: };
michael@0: 
michael@0: this.ThirdPartyCookieProbe.prototype = {
michael@0:   QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver]),
michael@0:   init: function() {
michael@0:     Services.obs.addObserver(this, "profile-before-change", false);
michael@0:     Services.obs.addObserver(this, "third-party-cookie-accepted", false);
michael@0:     Services.obs.addObserver(this, "third-party-cookie-rejected", false);
michael@0:   },
michael@0:   dispose: function() {
michael@0:     Services.obs.removeObserver(this, "profile-before-change");
michael@0:     Services.obs.removeObserver(this, "third-party-cookie-accepted");
michael@0:     Services.obs.removeObserver(this, "third-party-cookie-rejected");
michael@0:   },
michael@0:   /**
michael@0:    * Observe either
michael@0:    * - "profile-before-change" (no meaningful subject or data) - time to flush statistics and unregister; or
michael@0:    * - "third-party-cookie-accepted"/"third-party-cookie-rejected" with
michael@0:    *    subject: the nsIURI of the third-party that attempted to set the cookie;
michael@0:    *    data: a string holding the uri of the page seen by the user.
michael@0:    */
michael@0:   observe: function(docURI, topic, referrer) {
michael@0:     try {
michael@0:       if (topic == "profile-before-change") {
michael@0:         // A final flush, then unregister
michael@0:         this.flush();
michael@0:         this.dispose();
michael@0:       }
michael@0:       if (topic != "third-party-cookie-accepted"
michael@0:           && topic != "third-party-cookie-rejected") {
michael@0:         // Not a third-party cookie
michael@0:         return;
michael@0:       }
michael@0:       // Add host to this._thirdPartyCookies
michael@0:       // Note: nsCookieService passes "?" if the issuer is unknown.  Avoid
michael@0:       //       normalizing in this case since its not a valid URI.
michael@0:       let firstParty = (referrer === "?") ? referrer : normalizeHost(referrer);
michael@0:       let thirdParty = normalizeHost(docURI.QueryInterface(Ci.nsIURI).host);
michael@0:       let data = this._thirdPartyCookies.get(thirdParty);
michael@0:       if (!data) {
michael@0:         data = new RejectStats();
michael@0:         this._thirdPartyCookies.set(thirdParty, data);
michael@0:       }
michael@0:       if (topic == "third-party-cookie-accepted") {
michael@0:         data.addAccepted(firstParty);
michael@0:       } else {
michael@0:         data.addRejected(firstParty);
michael@0:       }
michael@0:     } catch (ex) {
michael@0:       if (ex instanceof Ci.nsIXPCException) {
michael@0:         if (ex.result == Cr.NS_ERROR_HOST_IS_IP_ADDRESS ||
michael@0:             ex.result == Cr.NS_ERROR_INSUFFICIENT_DOMAIN_LEVELS) {
michael@0:           return;
michael@0:         }
michael@0:       }
michael@0:       // Other errors should not remain silent.
michael@0:       Services.console.logStringMessage("ThirdPartyCookieProbe: Uncaught error " + ex + "\n" + ex.stack);
michael@0:     }
michael@0:   },
michael@0: 
michael@0:   /**
michael@0:    * Clear internal data, fill up corresponding histograms.
michael@0:    *
michael@0:    * @param {number} aNow (optional, used for testing purposes only)
michael@0:    * The current instant. Used to make tests time-independent.
michael@0:    */
michael@0:   flush: function(aNow = Date.now()) {
michael@0:     let updays = (aNow - this._latestFlush) / MILLISECONDS_PER_DAY;
michael@0:     if (updays <= 0) {
michael@0:       // Unlikely, but regardless, don't risk division by zero
michael@0:       // or weird stuff.
michael@0:       return;
michael@0:     }
michael@0:     this._latestFlush = aNow;
michael@0:     let acceptedSites = Services.telemetry.getHistogramById("COOKIES_3RDPARTY_NUM_SITES_ACCEPTED");
michael@0:     let rejectedSites = Services.telemetry.getHistogramById("COOKIES_3RDPARTY_NUM_SITES_BLOCKED");
michael@0:     let acceptedRequests = Services.telemetry.getHistogramById("COOKIES_3RDPARTY_NUM_ATTEMPTS_ACCEPTED");
michael@0:     let rejectedRequests = Services.telemetry.getHistogramById("COOKIES_3RDPARTY_NUM_ATTEMPTS_BLOCKED");
michael@0:     for (let [k, data] of this._thirdPartyCookies) {
michael@0:       acceptedSites.add(data.countAcceptedSites / updays);
michael@0:       rejectedSites.add(data.countRejectedSites / updays);
michael@0:       acceptedRequests.add(data.countAcceptedRequests / updays);
michael@0:       rejectedRequests.add(data.countRejectedRequests / updays);
michael@0:     }
michael@0:     this._thirdPartyCookies.clear();
michael@0:   }
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * Data gathered on cookies that a third party site has attempted to set.
michael@0:  *
michael@0:  * Privacy note: the only data actually sent to the server is the size of
michael@0:  * the sets.
michael@0:  *
michael@0:  * @constructor
michael@0:  */
michael@0: let RejectStats = function() {
michael@0:   /**
michael@0:    * The set of all sites for which we have accepted third-party cookies.
michael@0:    */
michael@0:   this._acceptedSites = new Set();
michael@0:   /**
michael@0:    * The set of all sites for which we have rejected third-party cookies.
michael@0:    */
michael@0:   this._rejectedSites = new Set();
michael@0:   /**
michael@0:    * Total number of attempts to set a third-party cookie that have
michael@0:    * been accepted. Two accepted attempts on the same site will both
michael@0:    * augment this count.
michael@0:    */
michael@0:   this._acceptedRequests = 0;
michael@0:   /**
michael@0:    * Total number of attempts to set a third-party cookie that have
michael@0:    * been rejected. Two rejected attempts on the same site will both
michael@0:    * augment this count.
michael@0:    */
michael@0:   this._rejectedRequests = 0;
michael@0: };
michael@0: RejectStats.prototype = {
michael@0:   addAccepted: function(firstParty) {
michael@0:     this._acceptedSites.add(firstParty);
michael@0:     this._acceptedRequests++;
michael@0:   },
michael@0:   addRejected: function(firstParty) {
michael@0:     this._rejectedSites.add(firstParty);
michael@0:     this._rejectedRequests++;
michael@0:   },
michael@0:   get countAcceptedSites() {
michael@0:     return this._acceptedSites.size;
michael@0:   },
michael@0:   get countRejectedSites() {
michael@0:     return this._rejectedSites.size;
michael@0:   },
michael@0:   get countAcceptedRequests() {
michael@0:     return this._acceptedRequests;
michael@0:   },
michael@0:   get countRejectedRequests() {
michael@0:     return this._rejectedRequests;
michael@0:   }
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * Normalize a host to its eTLD + 1.
michael@0:  */
michael@0: function normalizeHost(host) {
michael@0:   return Services.eTLD.getBaseDomainFromHost(host);
michael@0: };