feat($http): support sending XSRF token to whitelisted origins

Normally, the XSRF token will not be set for cross-origin requests.
With this commit, it is possible to whitelist additional origins, so that requests to these origins
will include the XSRF token header.

Fixes angular#7862

src/.eslintrc.json

@@ -161,6 +161,7 @@
     "urlResolve": false,
     "urlIsSameOrigin": false,
     "urlIsSameOriginAsBaseUrl": false,
+    "urlIsAllowedOriginChecker": false,
 
     /* ng/controller.js */
     "identifierForController": false,

src/ng/http.js

@@ -34,7 +34,7 @@ function $HttpParamSerializerProvider() {
    * * `{'foo': {'bar':'baz'}}` results in `foo=%7B%22bar%22%3A%22baz%22%7D` (stringified and encoded representation of an object)
    *
    * Note that serializer will sort the request parameters alphabetically.
-   * */
+   */
 
   this.$get = function() {
     return function ngParamSerializer(params) {
@@ -101,7 +101,7 @@ function $HttpParamSerializerJQLikeProvider() {
    * });
    * ```
    *
-   * */
+   */
   this.$get = function() {
     return function jQueryLikeParamSerializer(params) {
       if (!params) return '';
@@ -261,7 +261,7 @@ function isSuccess(status) {
  *
  * @description
  * Use `$httpProvider` to change the default behavior of the {@link ng.$http $http} service.
- * */
+ */
 function $HttpProvider() {
   /**
    * @ngdoc property
@@ -315,7 +315,7 @@ function $HttpProvider() {
    * - **`defaults.xsrfHeaderName`** - {string} - Name of HTTP header to populate with the
    * XSRF token. Defaults value is `'X-XSRF-TOKEN'`.
    *
-   **/
+   */
   var defaults = this.defaults = {
     // transform incoming response data
     transformResponse: [defaultHttpResponseTransform],
@@ -362,7 +362,7 @@ function $HttpProvider() {
    *
    * @returns {boolean|Object} If a value is specified, returns the $httpProvider for chaining.
    *    otherwise, returns the current configured value.
-   **/
+   */
   this.useApplyAsync = function(value) {
     if (isDefined(value)) {
       useApplyAsync = !!value;
@@ -383,9 +383,49 @@ function $HttpProvider() {
    * array, on request, but reverse order, on response.
    *
    * {@link ng.$http#interceptors Interceptors detailed info}
-   **/
+   */
   var interceptorFactories = this.interceptors = [];
 
+  /**
+   * @ngdoc property
+   * @name $httpProvider#xsrfWhitelistedOrigins
+   * @description
+   *
+   * Array containing URLs whose origins are considered trusted enough to receive the XSRF token.
+   * See the {@link ng.$http#security-considerations Security Considerations} sections for more
+   * details on XSRF.
+   *
+   * **Note:** An "origin" consists of the [URI scheme](https://en.wikipedia.org/wiki/URI_scheme),
+   * the [hostname](https://en.wikipedia.org/wiki/Hostname) and the
+   * [port number](https://en.wikipedia.org/wiki/Port_(computer_networking).
+   *
+   * <div class="alert alert-warning">
+   *   It is not possible to whitelist specific URLs/paths. The `path`, `query` and `fragment` parts
+   *   of a URL will be ignored. For example, `https://foo.com/path/bar?query=baz#fragment` will be
+   *   treated as `https://foo.com/`, meaning that **all** requests to URLs starting with
+   *   `https://foo.com/` will include the XSRF token.
+   * </div>
+   *
+   * @example
+   *
+   * ```js
+   * // App served from `https://example.com/`.
+   * angular.
+   *   module('xsrfWhitelistedOriginsExample', []).
+   *   config(['$httpProvider', function($httpProvider) {
+   *     $httpProvider.xsrfWhitelistedOrigins.push('https://api.example.com/');
+   *   }]).
+   *   run(['$http', function($http) {
+   *     // The XSRF token will be sent.
+   *     $http.get('https://api.example.com/preferences').then(...);
+   *
+   *     // The XSRF token will NOT be sent.
+   *     $http.get('https://stats.example.com/activity').then(...);
+   *   }]);
+   * ```
+   */
+  var xsrfWhitelistedOrigins = this.xsrfWhitelistedOrigins = [];
+
   this.$get = ['$browser', '$httpBackend', '$$cookieReader', '$cacheFactory', '$rootScope', '$q', '$injector', '$sce',
       function($browser, $httpBackend, $$cookieReader, $cacheFactory, $rootScope, $q, $injector, $sce) {
 
@@ -409,6 +449,11 @@ function $HttpProvider() {
           ? $injector.get(interceptorFactory) : $injector.invoke(interceptorFactory));
     });
 
+    /**
+     * A function to check request URLs against a list of allowed origins.
+     */
+    var urlIsAllowedOrigin = urlIsAllowedOriginChecker(xsrfWhitelistedOrigins);
+
     /**
      * @ngdoc service
      * @kind function
@@ -765,25 +810,42 @@ function $HttpProvider() {
      * which the attacker can trick an authenticated user into unknowingly executing actions on your
      * website. AngularJS provides a mechanism to counter XSRF. When performing XHR requests, the
      * $http service reads a token from a cookie (by default, `XSRF-TOKEN`) and sets it as an HTTP
-     * header (`X-XSRF-TOKEN`). Since only JavaScript that runs on your domain could read the
-     * cookie, your server can be assured that the XHR came from JavaScript running on your domain.
-     * The header will not be set for cross-domain requests.
+     * header (by default `X-XSRF-TOKEN`). Since only JavaScript that runs on your domain could read
+     * the cookie, your server can be assured that the XHR came from JavaScript running on your
+     * domain.
      *
      * To take advantage of this, your server needs to set a token in a JavaScript readable session
      * cookie called `XSRF-TOKEN` on the first HTTP GET request. On subsequent XHR requests the
-     * server can verify that the cookie matches `X-XSRF-TOKEN` HTTP header, and therefore be sure
-     * that only JavaScript running on your domain could have sent the request. The token must be
-     * unique for each user and must be verifiable by the server (to prevent the JavaScript from
+     * server can verify that the cookie matches the `X-XSRF-TOKEN` HTTP header, and therefore be
+     * sure that only JavaScript running on your domain could have sent the request. The token must
+     * be unique for each user and must be verifiable by the server (to prevent the JavaScript from
      * making up its own tokens). We recommend that the token is a digest of your site's
      * authentication cookie with a [salt](https://en.wikipedia.org/wiki/Salt_(cryptography&#41;)
      * for added security.
      *
-     * The name of the headers can be specified using the xsrfHeaderName and xsrfCookieName
-     * properties of either $httpProvider.defaults at config-time, $http.defaults at run-time,
-     * or the per-request config object.
+     * The header will &mdash; by default &mdash; **not** be set for cross-domain requests. This
+     * prevents unauthorized servers (e.g. malicious or compromized 3rd-party APIs) from gaining
+     * access to your users' XSRF tokens and exposing them to Cross Site Request Forgery. If you
+     * want to, you can whitelist additional origins to also receive the XSRF token, by adding them
+     * to {@link ng.$httpProvider#xsrfWhitelistedOrigins xsrfWhitelistedOrigins}. This might be
+     * useful, for example, if your application, served from `example.com`, needs to access your API
+     * at `api.example.com`.
+     * See {@link ng.$httpProvider#xsrfWhitelistedOrigins $httpProvider.xsrfWhitelistedOrigins} for
+     * more details.
+     *
+     * <div class="alert alert-danger">
+     *   **Warning**<br />
+     *   Only whitelist origins that you have control over and make sure you understand the
+     *   implications of doing so.
+     * </div>
+     *
+     * The name of the cookie and the header can be specified using the `xsrfCookieName` and
+     * `xsrfHeaderName` properties of either `$httpProvider.defaults` at config-time,
+     * `$http.defaults` at run-time, or the per-request config object.
      *
      * In order to prevent collisions in environments where multiple AngularJS apps share the
-     * same domain or subdomain, we recommend that each application uses unique cookie name.
+     * same domain or subdomain, we recommend that each application uses a unique cookie name.
+     *
      *
      * @param {object} config Object describing the request to be made and how it should be
      *    processed. The object has following properties:
@@ -1343,7 +1405,7 @@ function $HttpProvider() {
       // if we won't have the response in cache, set the xsrf headers and
       // send the request to the backend
       if (isUndefined(cachedResp)) {
-        var xsrfValue = urlIsSameOrigin(config.url)
+        var xsrfValue = urlIsAllowedOrigin(config.url)
             ? $$cookieReader()[config.xsrfCookieName || defaults.xsrfCookieName]
             : undefined;
         if (xsrfValue) {

src/ng/urlUtils.js

@@ -84,7 +84,8 @@ function urlResolve(url) {
 }
 
 /**
- * Parse a request URL and determine whether this is a same-origin request as the application document.
+ * Parse a request URL and determine whether this is a same-origin request as the application
+ * document.
  *
  * @param {string|object} requestUrl The url of the request as a string that will be resolved
  * or a parsed URL object.
@@ -109,37 +110,66 @@ function urlIsSameOriginAsBaseUrl(requestUrl) {
 }
 
 /**
- * Determines if two URLs share the same origin.
+ * Create a function that can check a URL's origin against a list of allowed/whitelisted origins.
+ * The current location's origin is implicitly trusted.
  *
- * @param {string|object} url1 First URL to compare as a string or a normalized URL in the form of
- *     a dictionary object returned by `urlResolve()`.
- * @param {string|object} url2 Second URL to compare as a string or a normalized URL in the form of
+ * @param {string[]} whitelistedOriginUrls - A list of URLs (strings), whose origins are trusted.
+ *
+ * @returns {Function} - A function that receives a URL (string or parsed URL object) and returns
+ *     whether it is of an allowed origin.
+ */
+function urlIsAllowedOriginChecker(whitelistedOriginUrls) {
+  var parsedAllowedOriginUrls = [originUrl].concat(whitelistedOriginUrls.map(urlResolve));
+
+  /**
+   * Check whether the specified URL (string or parsed URL object) has an origin that is allowed
+   * based on a list of whitelisted-origin URLs. The current location's origin is implicitly
+   * trusted.
+   *
+   * @param {string|Object} requestUrl - The URL to be checked (provided as a string that will be
+   *     resolved or a parsed URL object).
+   *
+   * @returns {boolean} - Whether the specified URL is of an allowed origin.
+   */
+  return function urlIsAllowedOrigin(requestUrl) {
+    var parsedUrl = isString(requestUrl) ? urlResolve(requestUrl) : requestUrl;
+    return parsedAllowedOriginUrls.some(urlsAreSameOrigin.bind(null, parsedUrl));
+  };
+}
+
+/**
+ * Determine if two URLs share the same origin.
+ *
+ * @param {string|Object} url1 - First URL to compare as a string or a normalized URL in the form of
  *     a dictionary object returned by `urlResolve()`.
- * @return {boolean} True if both URLs have the same origin, and false otherwise.
+ * @param {string|object} url2 - Second URL to compare as a string or a normalized URL in the form
+ *     of a dictionary object returned by `urlResolve()`.
+ *
+ * @returns {boolean} - True if both URLs have the same origin, and false otherwise.
  */
 function urlsAreSameOrigin(url1, url2) {
-  url1 = (isString(url1)) ? urlResolve(url1) : url1;
-  url2 = (isString(url2)) ? urlResolve(url2) : url2;
+  url1 = isString(url1) ? urlResolve(url1) : url1;
+  url2 = isString(url2) ? urlResolve(url2) : url2;
 
   return (url1.protocol === url2.protocol &&
           url1.host === url2.host);
 }
 
 /**
  * Returns the current document base URL.
- * @return {string}
+ * @returns {string}
  */
 function getBaseUrl() {
   if (window.document.baseURI) {
     return window.document.baseURI;
   }
 
-  // document.baseURI is available everywhere except IE
+  // `document.baseURI` is available everywhere except IE
   if (!baseUrlParsingNode) {
     baseUrlParsingNode = window.document.createElement('a');
     baseUrlParsingNode.href = '.';
 
-    // Work-around for IE bug described in Implementation Notes. The fix in urlResolve() is not
+    // Work-around for IE bug described in Implementation Notes. The fix in `urlResolve()` is not
     // suitable here because we need to track changes to the base URL.
     baseUrlParsingNode = baseUrlParsingNode.cloneNode(false);
   }

test/.eslintrc.json

@@ -152,7 +152,8 @@
     /* urlUtils.js */
     "urlResolve": false,
     "urlIsSameOrigin": false,
-    "urlIsSameOriginAsBaseUrl": true,
+    "urlIsSameOriginAsBaseUrl": false,
+    "urlIsAllowedOriginChecker": false,
 
     /* karma */
     "dump": false,