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.
7 * Third party authentication support for the remoting web-app.
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.
23 /** @suppress {duplicate} */
24 var remoting = remoting || {};
28 * Encapsulates the logic to fetch a third party authentication token.
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.
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_ = remoting.generateXsrfToken();
45 this.tokenUrlPatterns_ = tokenUrlPatterns;
46 this.hostPublicKey_ = hostPublicKey;
47 if (chrome.identity) {
48 /** @type {function():void}
50 this.fetchTokenInternal_ = this.fetchTokenIdentityApi_.bind(this);
51 this.redirectUri_ = 'https://' + window.location.hostname +
52 '.chromiumapp.org/ThirdPartyAuth';
54 this.fetchTokenInternal_ = this.fetchTokenWindowOpen_.bind(this);
55 this.redirectUri_ = remoting.settings.THIRD_PARTY_AUTH_REDIRECT_URI;
60 * Fetch a token with the parameters configured in this object.
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_();
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(
74 hostPermissions.getPermission(
75 this.fetchTokenInternal_,
76 this.failFetchToken_);
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_();
87 * Parse the access token from the URL to which we were redirected.
89 * @param {string} responseUrl The URL to which we were redirected.
92 remoting.ThirdPartyTokenFetcher.prototype.parseRedirectUrl_ =
93 function(responseUrl) {
95 var sharedSecret = '';
97 if (responseUrl && responseUrl.search('#') >= 0) {
98 var query = responseUrl.substring(responseUrl.search('#') + 1);
99 var parts = query.split('&');
100 /** @type {Object.<string>} */
102 for (var i = 0; i < parts.length; i++) {
103 var pair = parts[i].split('=');
104 queryArgs[decodeURIComponent(pair[0])] = decodeURIComponent(pair[1]);
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) {
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'];
126 this.onThirdPartyTokenFetched_(token, sharedSecret);
130 * Build a full token request URL from the parameters in this object.
132 * @return {string} Full URL to request a token.
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_
148 * Fetch a token by opening a new window and redirecting to a content script.
151 remoting.ThirdPartyTokenFetcher.prototype.fetchTokenWindowOpen_ = function() {
152 /** @type {remoting.ThirdPartyTokenFetcher} */
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);
161 chrome.extension.onMessage.addListener(tokenMessageListener);
162 window.open(fullTokenUrl, '_blank', 'location=yes,toolbar=no,menubar=no');
166 * Fetch a token from a token server using the identity.launchWebAuthFlow API.
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));