透過 OAuth 連結帳戶

OAuth 連結類型支援兩種符合業界標準的 OAuth 2.0 流程，分別是隱含和授權程式碼流程。

In the implicit code flow, Google opens your authorization endpoint in the user's browser. After successful sign in, you return a long-lived access token to Google. This access token is now included in every request sent from the Assistant to your Action.

In the authorization code flow, you need two endpoints:

• The authorization endpoint, which is responsible for presenting the sign-in UI to your users that aren't already signed in and recording consent to the requested access in the form of a short-lived authorization code.
• The token exchange endpoint, which is responsible for two types of exchanges:
  1. Exchanges an authorization code for a long-lived refresh token and a short-lived access token. This exchange happens when the user goes through the account linking flow.
  2. Exchanges a long-lived refresh token for a short-lived access token. This exchange happens when Google needs a new access token because the one it had expired.

Although the implicit code flow is simpler to implement, Google recommends that access tokens issued using the implicit flow never expire, because using token expiration with the implicit flow forces the user to link their account again. If you need token expiration for security reasons, you should strongly consider using the auth code flow instead.

實作 OAuth 帳戶連結

設定專案

如要將專案設為使用 OAuth 連結，請按照下列步驟操作：

1. 開啟「Actions Console」，然後選取要使用的專案。
2. 按一下「開發」分頁標籤，然後選擇「帳戶連結」。
3. 啟用「帳戶連結」旁的切換鈕。
4. 在「建立帳戶」部分中，選取「否，我只想允許在我的網站上建立帳戶」。

5. 在「連結類型」中，選取「OAuth」和「授權碼」。

   

6. 在「客戶資訊」部分中：

   • 將值指派給「Actions to Google」的用戶端 ID，即可識別來自 Google 的要求。
   • 記下「Google 核發給您動作的用戶端 ID」值；
   • 插入授權和權杖交換端點的網址。

6. 點按「儲存」。

實作 OAuth 伺服器

An OAuth 2.0 server implementation of the authorization code flow consists of two endpoints, which your service makes available by HTTPS. The first endpoint is the authorization endpoint, which is responsible for finding or 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. The second endpoint is the token exchange endpoint, which is used to obtain encrypted strings called tokens that authorize the Action user to access your service.

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

OAuth 2.0 auth code flow session initiated by Google has the following flow:

1. Google opens your authorization endpoint in the user's browser. If the flow started on a voice-only device for an Action, Google would transfer the execution to a phone.

2. 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.

3. Your service creates an authorization code and returns it to Google by redirecting the user's browser back to Google with the authorization code attached to the request.

4. Google sends the authorization code to your token exchange endpoint, which verifies the authenticity of the code and returns an access token and a refresh token. The access token is a short-lived token that your service accepts as credentials to access APIs. The refresh token is a long-lived token that Google can store and use to acquire new access tokens when they expire.

5. After the user has completed the account linking flow, every subsequent request sent from the Assistant to your fulfillment webhook contains an access token.

Handle authorization requests

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

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&scope=REQUESTED_SCOPES&response_type=code

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

1. Verify that the client_id matches the Google client ID you registered with Google, and that the redirect_uri matches the redirect URL provided by Google for your service. These checks are important to prevent granting access to unintended or misconfigured client apps.

   If you support multiple OAuth 2.0 flows, also confirm that the response_type is code.

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 authorization code that Google will use to access your API. The authorization code can be any string value, but it must uniquely represent the user, the client the token is for, and the code's expiration time, and it must not be guessable. You typically issue authorization codes that expire after approximately 10 minutes.

4. 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.

5. Redirect the user's browser to the URL specified by the redirect_uri parameter. Include the authorization code you just generated and the original, unmodified state value when you redirect by appending the code and state parameters. The following is an example of the resulting URL:

   https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_ID?code=AUTHORIZATION_CODE&state=STATE_STRING

Handle token exchange requests

Your service's token exchange endpoint is responsible for two kinds of token exchanges:

• Exchange authorization codes for access tokens and refresh tokens
• Exchange refresh tokens for access tokens

Token exchange requests include the following parameters:

Exchange authorization codes for access tokens and refresh tokens

After the user signs in and your authorization endpoint returns a short-lived authorization code to Google, Google sends a request to your token exchange endpoint to exchange the authorization code for an access token and a refresh token.

For these requests, the value of grant_type is authorization_code, and the value of code is the value of the authorization code you previously granted to Google. The following is an example of a request to exchange an authorization code for an access token and a refresh token:

POST /token HTTP/1.1
Host: oauth2.example.com
Content-Type: application/x-www-form-urlencoded

client_id=GOOGLE_CLIENT_ID&client_secret=GOOGLE_CLIENT_SECRET&grant_type=authorization_code&code=AUTHORIZATION_CODE&redirect_uri=REDIRECT_URI

To exchange authorization codes for an access token and a refresh token, your token exchange endpoint responds to POST requests executing the following steps:

1. Verify that the client_id identifies the request origin as an authorized origin, and that the client_secret matches the expected value.
2. Verify the following:
   • The authorization code is valid and not expired, and the client ID specified in the request matches the client ID associated with the authorization code.
   • The URL specified by the redirect_uri parameter is identical to the value used in the initial authorization request.
3. If you cannot verify all of the above criteria, return an HTTP 400 Bad Request error with {"error": "invalid_grant"} as the body.
4. Otherwise, using the user ID from the authorization code, generate a refresh token and an access token. These tokens can be any string value, but they must uniquely represent the user and the client the token is for, and they must not be guessable. For access tokens, also record the expiration time of the token (typically an hour after you issue the token). Refresh tokens do not expire.
5. Return the following JSON object in the body of the HTTPS response:

   {
   "token_type": "Bearer",
   "access_token": "ACCESS_TOKEN",
   "refresh_token": "REFRESH_TOKEN",
   "expires_in": SECONDS_TO_EXPIRATION
   }

Google stores the access token and the refresh token for the user and records the expiration of the access token. When the access token expires, Google uses the refresh token to get a new access token from your token exchange endpoint.

Exchange refresh tokens for access tokens

When an access token expires, Google sends a request to your token exchange endpoint to exchange a refresh token for a new access token.

For these requests, the value of grant_type is refresh_token, and the value of refresh_token is the value of the refresh token you previously granted to Google. The following is an example of a request to exchange a refresh token for an access token:

POST /token HTTP/1.1
Host: oauth2.example.com
Content-Type: application/x-www-form-urlencoded

client_id=GOOGLE_CLIENT_ID&client_secret=GOOGLE_CLIENT_SECRET&grant_type=refresh_token&refresh_token=REFRESH_TOKEN

To exchange a refresh token for an access token, your token exchange endpoint responds to POST requests executing the following steps:

1. Verify that the client_id identifies the request origin as Google, and that the client_secret matches the expected value.
2. Verify that the refresh token is valid, and that the client ID specified in the request matches the client ID associated with the refresh token.
3. If you cannot verify all of the above criteria, return an HTTP 400 Bad Request error with {"error": "invalid_grant"} as the body.
4. Otherwise, use the user ID from the refresh token to generate an access token. These tokens can be any string value, but they must uniquely represent the user and the client the token is for, and they must not be guessable. For access tokens, also record the expiration time of the token (typically an hour after you issue the token).
5. Return the following JSON object in the body of the HTTPS response:

   {
   "token_type": "Bearer",
   "access_token": "ACCESS_TOKEN",
   "expires_in": SECONDS_TO_EXPIRATION
   }

設計驗證流程的語音使用者介面

檢查使用者是否已通過驗證，並啟動帳戶連結流程

1. 在 Actions 主控台中開啟 Actions Builder 專案。
2. 建立新的場景，以便在動作中開始連結帳戶：
   1. 按一下「Scenes」。
   2. 按一下「add」圖示 (+) 即可新增場景。
3. 在新建立的場景中，按一下「Conditions」(條件) 圖示 add。
4. 新增條件，檢查與對話相關聯的使用者是否為已驗證的使用者。如果檢查失敗，您的動作就無法在對話期間執行帳戶連結，而是應改回提供不需要帳戶連結的功能。
   1. 在「Condition」(條件) 下方的 Enter new expression 欄位中，輸入下列邏輯：user.verificationStatus != "VERIFIED"
   2. 在「轉換」下方，選取不需要連結帳戶的場景，或不需要訪客專屬功能的進入點。

1. 按一下「條件」的「新增」圖示 add。
2. 新增條件，在使用者沒有相關聯的身分時觸發帳戶連結流程。
   1. 在「Condition」(條件) 下方的 Enter new expression 欄位中，輸入下列邏輯：user.verificationStatus == "VERIFIED"
   2. 在「轉換」下方，選取「帳戶連結」系統場景。
   3. 點按「儲存」。

儲存後，名為 <SceneName>_AccountLinking 的帳戶連結系統場景就會新增至專案中。

自訂帳戶連結情境

1. 在「場景」下方，選取帳戶連結系統場景。
2. 按一下「Send 提示」，然後新增簡短句子，說明動作需要存取其身分的原因 (例如「如要儲存偏好設定」)。
3. 點按「儲存」。

1. 在「條件」下方，按一下「如果使用者成功完成帳戶連結」。
2. 設定使用者同意連結帳戶時，流程的後續步驟。 舉例來說，呼叫 Webhook 以處理任何所需的自訂商業邏輯，然後切換回原始場景。
3. 點按「儲存」。

1. 在「條件」下方，按一下「如果使用者取消或關閉帳戶連結」。
2. 如果使用者不同意連結帳戶，請設定流程。例如，傳送已確認的訊息，然後重新導向至提供不需要連結帳戶的功能的場景。
3. 點按「儲存」。

1. 在「條件」下方，按一下「如果發生系統或網路錯誤」。
2. 設定若帳戶連結流程因系統或網路錯誤而無法順利完成時，流程該如何繼續。 例如，傳送已確認的訊息，然後重新導向至提供不需要連結帳戶的功能的場景。
3. 點按「儲存」。

處理資料存取要求

如果 Google 助理要求包含存取權杖，請先檢查存取權杖是否有效 (且未過期)，然後從資料庫中擷取相關聯的使用者帳戶。