remoting/webapp/crd/js/third_party_token_fetcher.js

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * @fileoverview
   7  * Third party authentication support for the remoting web-app.
   8  *
   9  * When third party authentication is being used, the client must request both a
  10  * token and a shared secret from a third-party server. The server can then
  11  * present the user with an authentication page, or use any other method to
  12  * authenticate the user via the browser. Once the user is authenticated, the
  13  * server will redirect the browser to a URL containing the token and shared
  14  * secret in its fragment. The client then sends only the token to the host.
  15  * The host signs the token, then contacts the third-party server to exchange
  16  * the token for the shared secret. Once both client and host have the shared
  17  * secret, they use a zero-disclosure mutual authentication protocol to
  18  * negotiate an authentication key, which is used to establish the connection.
  19  */
  20
  21 'use strict';
  22
  23 /** @suppress {duplicate} */
  24 var remoting = remoting || {};
  25
  26 /**
  27  * @constructor
  28  * Encapsulates the logic to fetch a third party authentication token.
  29  *
  30  * @param {string} tokenUrl Token-issue URL received from the host.
  31  * @param {string} hostPublicKey Host public key (DER and Base64 encoded).
  32  * @param {string} scope OAuth scope to request the token for.
  33  * @param {Array.<string>} tokenUrlPatterns Token URL patterns allowed for the
  34  *     domain, received from the directory server.
  35  * @param {function(string, string):void} onThirdPartyTokenFetched Callback.
  36  */
  37 remoting.ThirdPartyTokenFetcher = function(
  38     tokenUrl, hostPublicKey, scope, tokenUrlPatterns,
  39     onThirdPartyTokenFetched) {
  40   this.tokenUrl_ = tokenUrl;
  41   this.tokenScope_ = scope;
  42   this.onThirdPartyTokenFetched_ = onThirdPartyTokenFetched;
  43   this.failFetchToken_ = function() { onThirdPartyTokenFetched('', ''); };
  44   this.xsrfToken_ = base.generateXsrfToken();
  45   this.tokenUrlPatterns_ = tokenUrlPatterns;
  46   this.hostPublicKey_ = hostPublicKey;
  47   if (chrome.identity) {
  48     /** @type {function():void}
  49      * @private */
  50     this.fetchTokenInternal_ = this.fetchTokenIdentityApi_.bind(this);
  51     this.redirectUri_ = 'https://' + window.location.hostname +
  52         '.chromiumapp.org/ThirdPartyAuth';
  53   } else {
  54     this.fetchTokenInternal_ = this.fetchTokenWindowOpen_.bind(this);
  55     this.redirectUri_ = remoting.settings.THIRD_PARTY_AUTH_REDIRECT_URI;
  56   }
  57 };
  58
  59 /**
  60  * Fetch a token with the parameters configured in this object.
  61  */
  62 remoting.ThirdPartyTokenFetcher.prototype.fetchToken = function() {
  63   // If there is no list of patterns, this host cannot use a token URL.
  64   if (!this.tokenUrlPatterns_) {
  65     console.error('No token URLs are allowed for this host');
  66     this.failFetchToken_();
  67   }
  68
  69   // Verify the host-supplied URL matches the domain's allowed URL patterns.
  70   for (var i = 0; i < this.tokenUrlPatterns_.length; i++) {
  71     if (this.tokenUrl_.match(this.tokenUrlPatterns_[i])) {
  72       var hostPermissions = new remoting.ThirdPartyHostPermissions(
  73           this.tokenUrl_);
  74       hostPermissions.getPermission(
  75           this.fetchTokenInternal_,
  76           this.failFetchToken_);
  77       return;
  78     }
  79   }
  80   // If the URL doesn't match any pattern in the list, refuse to access it.
  81   console.error('Token URL does not match the domain\'s allowed URL patterns.' +
  82       ' URL: ' + this.tokenUrl_ + ', patterns: ' + this.tokenUrlPatterns_);
  83   this.failFetchToken_();
  84 };
  85
  86 /**
  87  * Parse the access token from the URL to which we were redirected.
  88  *
  89  * @param {string} responseUrl The URL to which we were redirected.
  90  * @private
  91  */
  92 remoting.ThirdPartyTokenFetcher.prototype.parseRedirectUrl_ =
  93     function(responseUrl) {
  94   var token = '';
  95   var sharedSecret = '';
  96
  97   if (responseUrl && responseUrl.search('#') >= 0) {
  98     var query = responseUrl.substring(responseUrl.search('#') + 1);
  99     var parts = query.split('&');
 100     /** @type {Object.<string>} */
 101     var queryArgs = {};
 102     for (var i = 0; i < parts.length; i++) {
 103       var pair = parts[i].split('=');
 104       queryArgs[decodeURIComponent(pair[0])] = decodeURIComponent(pair[1]);
 105     }
 106
 107     // Check that 'state' contains the same XSRF token we sent in the request.
 108     if ('state' in queryArgs && queryArgs['state'] == this.xsrfToken_ &&
 109         'code' in queryArgs && 'access_token' in queryArgs) {
 110       // Terminology note:
 111       // In the OAuth code/token exchange semantics, 'code' refers to the value
 112       // obtained when the *user* authenticates itself, while 'access_token' is
 113       // the value obtained when the *application* authenticates itself to the
 114       // server ("implicitly", by receiving it directly in the URL fragment, or
 115       // explicitly, by sending the 'code' and a 'client_secret' to the server).
 116       // Internally, the piece of data obtained when the user authenticates
 117       // itself is called the 'token', and the one obtained when the host
 118       // authenticates itself (using the 'token' received from the client and
 119       // its private key) is called the 'shared secret'.
 120       // The client implicitly authenticates itself, and directly obtains the
 121       // 'shared secret', along with the 'token' from the redirect URL fragment.
 122       token = queryArgs['code'];
 123       sharedSecret = queryArgs['access_token'];
 124     }
 125   }
 126   this.onThirdPartyTokenFetched_(token, sharedSecret);
 127 };
 128
 129 /**
 130  * Build a full token request URL from the parameters in this object.
 131  *
 132  * @return {string} Full URL to request a token.
 133  * @private
 134  */
 135 remoting.ThirdPartyTokenFetcher.prototype.getFullTokenUrl_ = function() {
 136   return this.tokenUrl_ + '?' + remoting.xhr.urlencodeParamHash({
 137     'redirect_uri': this.redirectUri_,
 138     'scope': this.tokenScope_,
 139     'client_id': this.hostPublicKey_,
 140     // The webapp uses an "implicit" OAuth flow with multiple response types to
 141     // obtain both the code and the shared secret in a single request.
 142     'response_type': 'code token',
 143     'state': this.xsrfToken_
 144   });
 145 };
 146
 147 /**
 148  * Fetch a token by opening a new window and redirecting to a content script.
 149  * @private
 150  */
 151 remoting.ThirdPartyTokenFetcher.prototype.fetchTokenWindowOpen_ = function() {
 152   /** @type {remoting.ThirdPartyTokenFetcher} */
 153   var that = this;
 154   var fullTokenUrl = this.getFullTokenUrl_();
 155   // The function below can't be anonymous, since it needs to reference itself.
 156   /** @param {string} message Message received from the content script. */
 157   function tokenMessageListener(message) {
 158     that.parseRedirectUrl_(message);
 159     chrome.extension.onMessage.removeListener(tokenMessageListener);
 160   }
 161   chrome.extension.onMessage.addListener(tokenMessageListener);
 162   window.open(fullTokenUrl, '_blank', 'location=yes,toolbar=no,menubar=no');
 163 };
 164
 165 /**
 166  * Fetch a token from a token server using the identity.launchWebAuthFlow API.
 167  * @private
 168  */
 169 remoting.ThirdPartyTokenFetcher.prototype.fetchTokenIdentityApi_ = function() {
 170   var fullTokenUrl = this.getFullTokenUrl_();
 171   chrome.identity.launchWebAuthFlow(
 172     {'url': fullTokenUrl, 'interactive': true},
 173     this.parseRedirectUrl_.bind(this));
 174 };