Account linking with OAuth

The OAuth linking type supports two industry standard OAuth 2.0 flows, the implicit and authorization code flows.

在隐式代码流程中，Google 会在用户浏览器中打开您的授权端点。成功登录后，系统会向 Google 返回长期访问令牌。现在，从 Google 助理向你的 Action 发送的每个请求中都包含此访问令牌。

在授权代码流程中，您需要两个端点：

• 授权端点，该端点负责向尚未登录的用户显示登录界面，并以短期授权代码的形式记录所请求的访问。
• 令牌交换端点，负责两种类型的交换：
  1. 将授权代码交换为长期刷新令牌和短期访问令牌。用户完成帐号关联流程后，系统会进行这种交换。
  2. 将长期刷新令牌换成短期访问令牌。Google 需要新访问令牌时，由于此令牌已过期，因此会进行此交换。

虽然隐式代码流程的实现更简单，但 Google 建议通过隐式流程发出的访问令牌永远不会过期，因为将令牌过期与隐式流程一起使用会强制用户再次关联其帐号。如果出于安全考虑需要令牌到期，强烈建议您考虑使用身份验证代码流程。

注意 ：请选择您希望实施的 OAuth 2.0 流程。如果需要，本指南的内容会根据您的选择重新加载。

身份验证代码 隐式流程

Implement OAuth account linking

Note: If you're implementing account linking to handle financial information, note that additional policies may apply to your Action. It can take us up to six weeks to review an Action with account linking for financial information, so factor that time in when planning your release schedule. To ease the review process, make sure you comply with the financial services policies before submitting your Action for review.

Configure the project

To configure your project to use OAuth linking, follow these steps:

1. Open the Actions Console and select the project you want to use.
2. Click the Develop tab and choose Account linking.
3. Enable the switch next to Account linking.
4. In the Account creation section, select No, I only want to allow account creation on my website.

5. In Linking type, select OAuth and Implicit.

   

6. In Client Information:

   • Assign a value to Client ID issued by your Actions to Google to identify requests coming from Google.
   • Insert the URLs for your Authorization and Token Exchange endpoints.

Note: If you want your client ID to be sent as a base64 encoded string, click the drop down arrow next to Configure your client (optional) and check the box Google to transmit clientID and secret via HTTP basic auth header.

6. Click Save.

Implement your OAuth server

To support the OAuth 2.0 implicit flow, your service makes an authorization endpoint available by HTTPS. This endpoint is responsible for authenticating and obtaining consent from users for data access. The authorization endpoint presents a sign-in UI to your users that aren't already signed in and records consent to the requested access.

When your Action needs to call one of your service's authorized APIs, Google uses this endpoint to get permission from your users to call these APIs on their behalf.

A typical OAuth 2.0 implicit flow session initiated by Google has the following flow:

1. Google opens your authorization endpoint in the user's browser. The user signs in if not signed in already, and grants Google permission to access their data with your API if they haven't already granted permission.
2. Your service creates an access token and returns it to Google by redirecting the user's browser back to Google with the access token attached to the request.
3. Google calls your service's APIs, and attaches the access token with each request. Your service verifies that the access token grants Google authorization to access the API and then completes the API call.

Handle authorization requests

When your Action needs to perform account linking via an OAuth 2.0 implicit flow, Google sends the user to your authorization endpoint with a request that includes the following parameters:

Authorization endpoint parameters
client_id	The client ID you assigned to Google.
redirect_uri	The URL to which you send the response to this request.
state	A bookkeeping value that is passed back to Google unchanged in the redirect URI.
response_type	The type of value to return in the response. For the OAuth 2.0 implicit flow, the response type is always token.

For example, if your authorization endpoint is available at https://myservice.example.com/auth, a request might look like:

GET https://myservice.example.com/auth?client_id=GOOGLE_CLIENT_ID&redirect_uri=REDIRECT_URI&state=STATE_STRING&response_type=token

For your authorization endpoint to handle sign-in requests, do the following steps:

1. Verify the client_id and redirect_uri values to prevent granting access to unintended or misconfigured client apps:

   • Confirm that the client_id matches the client ID you assigned to Google.
   • Confirm that the URL specified by the redirect_uri parameter has the following form:

     https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_ID

     YOUR_PROJECT_ID is the ID found on the Project settings page of the Actions Console.

2. Check if the user is signed in to your service. If the user isn't signed in, complete your service's sign-in or sign-up flow.

3. Generate an access token that Google will use to access your API. The access token can be any string value, but it must uniquely represent the user and the client the token is for and must not be guessable.

4. Send an HTTP response that redirects the user's browser to the URL specified by the redirect_uri parameter. Include all of the following parameters in the URL fragment:

   • access_token: the access token you just generated
   • token_type: the string bearer
   • state: the unmodified state value from the original request The following is an example of the resulting URL:

     https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_ID#access_token=ACCESS_TOKEN&token_type=bearer&state=STATE_STRING

Google's OAuth 2.0 redirect handler will receive the access token and confirm that the state value hasn't changed. After Google has obtained an access token for your service, Google will attach the token to subsequent calls to your Action as part of the AppRequest.

Design the voice user interface for the authentication flow

Warning: Don't give users a required account linking prompt at the start of the conversation with your Action. Instead, give unauthenticated users a guest flow to show how your Action works, and then only ask for account linking if it's necessary to proceed. If users are leaving the Action consistently because of account linking issues, Google will not actively promote the Action, which may decrease the Action's user traffic.

Note: You must use Actions Builder to build an Action that implements account linking.

Check if the user is verified and start the account linking flow

1. Open your Actions Builder project in the Actions Console.
2. Create a new scene to start account linking in your Action:
   1. Click Scenes.
   2. Click the add (+) icon to add a new scene.
3. In the newly created scene, click the add icon for Conditions.
4. Add a condition that checks if the user associated with the conversation is a a verified user. If the check fails, your Action can't perform account linking during the conversation, and should fall back to providing access to functionality that doesn't require account linking.
   1. In the Enter new expression field under Condition, enter the following logic: user.verificationStatus != "VERIFIED"
   2. Under Transition, select a scene that doesn't require account linking or a scene that is the entry point to guest-only functionality.

1. Click the add icon for Conditions.
2. Add a condition to trigger an account linking flow if the user doesn't have an associated identity.
   1. In the Enter new expression field under Condition, enter the following logic:: user.verificationStatus == "VERIFIED"
   2. Under Transition, select the Account Linking system scene.
   3. Click Save.

After saving, a new account linking system scene called <SceneName>_AccountLinking is added to your project.

Customize the account linking scene

1. Under Scenes, select the account linking system scene.
2. Click Send prompt and add a short sentence to describe to the user why the Action needs to access their identity (for example "To save your preferences").
3. Click Save.

1. Under Conditions, click If user successfully completes account linking.
2. Configure how the flow should proceed if the user agrees to link their account. For example, call the webhook to process any custom business logic required and transition back to the originating scene.
3. Click Save.

1. Under Conditions, click If user cancels or dismisses account linking.
2. Configure how the flow should proceed if the user doesn't agree to link their account. For example, send an acknowledging message and redirect to scenes that provide functionality that doesn't require account linking.
3. Click Save.

1. Under Conditions, click If system or network error occurs.
2. Configure how the flow should proceed if the account linking flow can't be completed because of system or network errors. For example, send an acknowledging message and redirect to scenes that provide functionality that doesn't require account linking.
3. Click Save.

Handle data access requests

If the Assistant request contains an access token, first check that the access token is valid (and not expired) and then retrieve the associated user account from your database.