Verify the host-supplied URL matches the domain's allowed URL patterns

remoting/android/java/src/org/chromium/chromoting/ThirdPartyTokenFetcher.java

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chromoting;
 
 import android.app.Activity;
 import android.content.ActivityNotFoundException;
 import android.content.ComponentName;
 import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.net.Uri;
+import android.text.TextUtils;
 import android.util.Base64;
 import android.util.Log;
 
 import java.security.SecureRandom;
+import java.util.ArrayList;
 import java.util.HashMap;
 
 /**
  * This class is responsible for fetching a third party token from the user using the OAuth2
  * implicit flow.  It pops up a third party login page located at |tokenurl|.  It relies on the
  * |ThirdPartyTokenFetcher$OAuthRedirectActivity| to intercept the access token from the redirect at
  * |REDIRECT_URI_SCHEME|://|REDIRECT_URI_HOST| upon successful login.
  */
 public class ThirdPartyTokenFetcher {
     /** Callback for receiving the token. */
@@ skipping 17 matching lines @@
     private Activity mContext;
 
     /**
      * An opaque value used by the client to maintain state between the request and callback.  The
      * authorization server includes this value when redirecting the user-agent back to the client.
      * The parameter is used for preventing cross-site request forgery. See
      * http://tools.ietf.org/html/rfc6749#section-10.12.
      */
     private final String mState;
 
-    /** URL of the third party login page. */
-    private final String mTokenUrl;
+    private final Callback mCallback;
 
-    /** The client identifier. See http://tools.ietf.org/html/rfc6749#section-2.2. */
-    private final String mClientId;
-
-    /** The scope of access request. See http://tools.ietf.org/html/rfc6749#section-3.3. */
-    private final String mScope;
-
-    private final Callback mCallback;
+    /** The list of TokenUrls allowed by the domain. */
+    private final ArrayList<String> mTokenUrlPatterns;
 
     private final String mRedirectUriScheme;
 
     private final String mRedirectUri;
 
     public ThirdPartyTokenFetcher(Activity context,
-                                  String tokenUrl,
-                                  String clientId,
-                                  String scope,
+                                  ArrayList<String> tokenUrlPatterns,
                                   Callback callback) {
         this.mContext = context;
-        this.mTokenUrl = tokenUrl;
-        this.mClientId = clientId;
         this.mState = generateXsrfToken();
-        this.mScope = scope;
         this.mCallback = callback;
+        this.mTokenUrlPatterns = tokenUrlPatterns;
 
         this.mRedirectUriScheme = context.getApplicationContext().getPackageName();
         this.mRedirectUri = mRedirectUriScheme + "://" + REDIRECT_URI_HOST;
     }
 
-    public void fetchToken() {
-        Uri.Builder uriBuilder = Uri.parse(mTokenUrl).buildUpon();
-        uriBuilder.appendQueryParameter("redirect_uri", this.mRedirectUri);
-        uriBuilder.appendQueryParameter("scope", mScope);
-        uriBuilder.appendQueryParameter("client_id", mClientId);
-        uriBuilder.appendQueryParameter("state", mState);
-        uriBuilder.appendQueryParameter("response_type", RESPONSE_TYPE);
+    /**
+     * @param tokenUrl URL of the third party login page.
+     * @param clientId The client identifier. See http://tools.ietf.org/html/rfc6749#section-2.2.
+     * @param scope The scope of access request. See http://tools.ietf.org/html/rfc6749#section-3.3.
+     */
+    public void fetchToken(String tokenUrl, String clientId, String scope) {
+        if (!isValidTokenUrl(tokenUrl)) {
+            failFetchToken(
+                    "Token URL does not match the domain\'s allowed URL patterns." +
+                    " URL: " + tokenUrl +
+                    ", patterns: " + TextUtils.join(",", this.mTokenUrlPatterns));
+            return;
+        }
 
-        Uri uri = uriBuilder.build();
+        Uri uri = buildRequestUri(tokenUrl, clientId, scope);
         Intent intent = new Intent(Intent.ACTION_VIEW, uri);
         Log.i("ThirdPartyAuth", "fetchToken() url:" + uri);
         OAuthRedirectActivity.setEnabled(mContext, true);
 
         try {
             mContext.startActivity(intent);
         } catch (ActivityNotFoundException e) {
             failFetchToken("No browser is installed to open the third party authentication page.");
         }
     }
 
+    private Uri buildRequestUri(String tokenUrl, String clientId, String scope) {
+        Uri.Builder uriBuilder = Uri.parse(tokenUrl).buildUpon();
+        uriBuilder.appendQueryParameter("redirect_uri", this.mRedirectUri);
+        uriBuilder.appendQueryParameter("scope", scope);
+        uriBuilder.appendQueryParameter("client_id", clientId);
+        uriBuilder.appendQueryParameter("state", mState);
+        uriBuilder.appendQueryParameter("response_type", RESPONSE_TYPE);
+
+        return uriBuilder.build();
+    }
+
+    /** Verify the host-supplied URL matches the domain's allowed URL patterns. */

[Lambros, 2014/06/18 23:29:06]

nit: s/Verify/Verifies. Function comments are descriptive, not imperative. They
describe what the function does. They don't tell the function what to do :)

This is from the C++ style guide:
http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml?showone=Functi...

[kelvinp, 2014/06/19 01:03:50]

Done.

+    private boolean isValidTokenUrl(String tokenUrl) {
+        for (String pattern : mTokenUrlPatterns) {
+            if (tokenUrl.matches(pattern)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     private boolean isValidIntent(Intent intent) {
         assert intent != null;
 
         String action = intent.getAction();
 
         Uri data = intent.getData();
         if (data != null) {
             return Intent.ACTION_VIEW.equals(action) &&
                    this.mRedirectUriScheme.equals(data.getScheme()) &&
                    REDIRECT_URI_HOST.equals(data.getHost());
@@ skipping 101 matching lines @@
             ComponentName component = new ComponentName(
                     context.getApplicationContext(),
                     ThirdPartyTokenFetcher.OAuthRedirectActivity.class);
             context.getPackageManager().setComponentEnabledSetting(
                     component,
                     enabledState,
                     PackageManager.DONT_KILL_APP);
         }
     }
 }