将 Google 帐号关联至 OAuth

使用业界标准 OAuth 2.0 隐式和授权代码流程关联账号。您的服务必须支持符合 OAuth 2.0 标准的授权和令牌交换端点。

在隐式流程中，Google 会在用户的浏览器中打开您的授权端点。成功登录后，您将向 Google 返回一个长期访问令牌。现在，此访问令牌会包含在 Google 发送的每个请求中。

在授权代码流程中，您需要两个端点：

• 授权端点，用于向尚未登录的用户显示登录界面。授权端点还会创建一个短期授权代码，以记录用户对所请求访问权限的同意情况。

• 令牌交换端点，负责两种类型的交换：

  1. 使用授权代码换取长期有效的刷新令牌和短期有效的访问令牌。当用户完成账号关联流程时，就会发生此交换。
  2. 将长期有效的刷新令牌换成短期有效的访问令牌。当 Google 需要新的访问令牌（因为现有访问令牌已过期）时，就会发生这种交换。

选择 OAuth 2.0 流程

虽然隐式流程更易于实现，但 Google 建议通过隐式流程签发的访问令牌永不过期。这是因为，在隐式流程中，令牌过期后，系统会强制用户重新关联其账号。如果您出于安全考虑需要令牌过期，我们强烈建议您改用授权码流程。

注意 ：使用以下按钮选择要实现的 OAuth 2.0 流程。如有需要，本指南的内容将重新加载，以符合您的选择。

隐式流程 授权代码

设计准则

本部分介绍了您为 OAuth 关联流程托管的用户屏幕的设计要求和建议。在 Google 应用调用该 API 后，您的平台会向用户显示登录 Google 页面和账号关联意见征求界面。同意关联账号后，系统会将用户重定向回 Google 的应用。

图 1.账号关联用户登录 Google 和同意屏幕。

要求

1. 您必须说明用户的账号将与 Google 相关联，而非 Google Home 或 Google 助理等特定 Google 产品相关联。

建议

建议您执行以下操作：

1. 显示 Google 的隐私权政策。在同意屏幕上添加指向 Google 隐私权政策的链接。

2. 要共享的数据。使用清晰简洁的语言告知用户 Google 需要哪些用户数据以及原因。

3. 添加醒目的号召性用语。在用户同意页面上提供明确的号召性用语，例如“同意并关联”。这是因为用户需要了解他们需要与 Google 分享哪些数据才能关联账号。

4. 可以取消。为用户提供返回或取消链接的途径，如果用户选择不进行关联。

5. 明确的登录流程。确保用户有明确的 Google 账号登录方法，例如用户名和密码字段或使用 Google 账号登录。

6. 能够解除关联。提供一种可让用户解除关联的机制，例如指向您平台上账号设置的网址。或者，您也可以添加指向 Google 账号的链接，以便用户管理其关联的账号。

7. 能够更改用户账号。建议用户切换账号的方法。如果用户通常拥有多个账号，这种做法尤为有益。

   • 如果用户必须关闭意见征求界面才能切换账号，请向 Google 发送可恢复的错误，以便用户可以使用 OAuth 关联和隐式流程登录所需的账号。

8. 添加您的徽标。在意见征求页面上显示您的公司徽标。 按照您的样式准则放置徽标。如果您还想显示 Google 的徽标，请参阅徽标和商标。

图 2.用户登录 Google 和征求用户同意界面的设计准则。

Create the project

Note: You can reuse an existing project and do not need to create a new project primarily for account linking.

To create your project to use account linking:

1. Go to the Google API Console.
2. Click Create project.
3. Enter a name or accept the generated suggestion.
4. Confirm or edit any remaining fields.
5. Click Create.

要查看您的项目ID：

1. Go to the Google API Console.
2. 在登录页面的表格中找到您的项目。项目ID出现在ID列中。

Configure your OAuth Consent Screen

The Google Account Linking process includes a consent screen which tells users the application requesting access to their data, what kind of data they are asking for and the terms that apply. You will need to configure your OAuth consent screen before generating a Google API client ID.

1. Open the OAuth consent screen page of the Google APIs console.
2. If prompted, select the project you just created.

3. On the "OAuth consent screen" page, fill out the form and click the “Save” button.

   Application name: The name of the application asking for consent. The name should accurately reflect your application and be consistent with the application name users see elsewhere. The application name will be shown on the Account Linking consent screen.

   Application logo: An image on the consent screen that will help users recognize your app. The logo is shown on Account linking consent screen and on account settings

   Support email: For users to contact you with questions about their consent.

   Scopes for Google APIs: Scopes allow your application to access your user's private Google data. For the Google Account Linking use case, default scope (email, profile, openid) is sufficient, you don’t need to add any sensitive scopes. It is generally a best practice to request scopes incrementally, at the time access is required, rather than up front. Learn more.

   Authorized domains: To protect you and your users, Google only allows applications that authenticate using OAuth to use Authorized Domains. Your applications' links must be hosted on Authorized Domains. Learn more.

   Application Homepage link: Home page for your application. Must be hosted on an Authorized Domain.

   Application Privacy Policy link: Shown on Google Account Linking consent screen. Must be hosted on an Authorized Domain.

   Application Terms of Service link (Optional): Must be hosted on an Authorized Domain.

   

   Figure 1. Google Account Linking Consent Screen for a fictitious Application, Tunery

4. Check "Verification Status", if your application needs verification then click the "Submit For Verification" button to submit your application for verification. Refer to OAuth verification requirements for details.

实现 OAuth 服务器

To support the OAuth 2.0 implicit flow, your service makes an authorization endpoint available by HTTPS. This endpoint is responsible for authentication 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 a Google application 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. To do so, redirect 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 a Google application 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.
user_locale	The Google Account language setting in RFC5646 format used to localize your content in the user's preferred language.

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

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

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

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 for Google to 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 receives the access token and confirms that the state value hasn't changed. After Google has obtained an access token for your service, Google attaches the token to subsequent calls to your service APIs.

处理 userinfo 请求

userinfo 端点是受 OAuth 2.0 保护的资源，会返回关联用户的声明。实现和托管 userinfo 端点是可选的，但以下用例除外：

• 使用 Google One Tap 登录关联的账号。
• Android TV 提供顺畅的订阅体验。

从您的令牌端点成功检索到访问令牌后，Google 会向您的 userinfo 端点发送请求，以检索关联用户的基本个人资料信息。

userinfo 端点请求标头
Authorization header	Bearer 类型的访问令牌。

例如，如果您的 userinfo 端点可通过 https://myservice.example.com/userinfo 时，请求可能如下所示：

GET /userinfo HTTP/1.1
Host: myservice.example.com
Authorization: Bearer ACCESS_TOKEN

为了让 userinfo 端点能够处理请求，请执行以下步骤：

1. 从 Authorization 标头中提取访问令牌，并返回与访问令牌相关联的用户的信息。
2. 如果访问令牌无效，则使用 WWW-Authenticate 响应标头返回 HTTP 401 Unauthorized 错误。下面是一个 userinfo 错误响应示例：

   HTTP/1.1 401 Unauthorized
   WWW-Authenticate: error="invalid_token",
   error_description="The Access Token expired"
   

   如果在关联过程中返回 401 未经授权错误或任何其他失败的错误响应，该错误将无法恢复，检索到的令牌将被舍弃，并且用户必须重新开始关联流程。

3. 如果访问令牌有效，则返回 HTTPS 正文中包含以下 JSON 对象的 HTTP 200 响应 回复：

   {
   "sub": "USER_UUID",
   "email": "EMAIL_ADDRESS",
   "given_name": "FIRST_NAME",
   "family_name": "LAST_NAME",
   "name": "FULL_NAME",
   "picture": "PROFILE_PICTURE",
   }
   

   如果您的 userinfo 端点返回 HTTP 200 成功响应，则系统会针对用户的 Google 账号注册检索到的令牌和声明。

   userinfo 端点响应
   sub	系统中用于识别用户的唯一 ID。
   email	用户的电子邮件地址。
   given_name	可选：用户的名字。
   family_name	可选：用户的姓氏。
   name	可选：用户的全名。
   picture	可选：用户的个人资料照片。

验证您的实现

You can validate your implementation by using the OAuth 2.0 Playground tool.

In the tool, do the following steps:

1. Click Configuration to open the OAuth 2.0 Configuration window.
2. In the OAuth flow field, select Client-side.
3. In the OAuth Endpoints field, select Custom.
4. Specify your OAuth 2.0 endpoint and the client ID you assigned to Google in the corresponding fields.
5. In the Step 1 section, don't select any Google scopes. Instead, leave this field blank or type a scope valid for your server (or an arbitrary string if you don't use OAuth scopes). When you're done, click Authorize APIs.
6. In the Step 2 and Step 3 sections, go through the OAuth 2.0 flow and verify that each step works as intended.

You can validate your implementation by using the Google Account Linking Demo tool.

In the tool, do the following steps:

1. Click the Sign-in with Google button.
2. Choose the account you'd like to link.
3. Enter the service ID.
4. Optionally enter one or more scopes that you will request access for.
5. Click Start Demo.
6. When prompted, confirm that you may consent and deny the linking request.
7. Confirm that you are redirected to your platform.