推送订阅身份验证

如果推送订阅使用身份验证，则 Pub/Sub 服务会对 JWT 进行签名，并在推送请求的授权标头中发送 JWT。JWT 包含声明和签名。

订阅者可以验证 JWT 并验证以下内容：

声明准确无误。
Pub/Sub 服务签署了声明。

如果订阅者使用防火墙，则无法接收推送请求。要接收推送请求，您必须关闭防火墙并验证 JWT。

准备工作

了解订阅。
了解推送订阅的运作方式。
创建推送订阅。

JWT 格式

JWT 是一个 OpenIDConnect JWT，由标头、声明集和签名组成。Pub/Sub 服务将 JWT 编码为使用句点分隔符的 base64 字符串。

例如，以下授权标头包含已编码的 JWT：

"Authorization" : "Bearer
eyJhbGciOiJSUzI1NiIsImtpZCI6IjdkNjgwZDhjNzBkNDRlOTQ3MTMzY2JkNDk5ZWJjMWE2MWMzZDVh
YmMiLCJ0eXAiOiJKV1QifQ.eyJhdWQiOiJodHRwczovL2V4YW1wbGUuY29tIiwiYXpwIjoiMTEzNzc0M
jY0NDYzMDM4MzIxOTY0IiwiZW1haWwiOiJnYWUtZ2NwQGFwcHNwb3QuZ3NlcnZpY2VhY2NvdW50LmNvb
SIsImVtYWlsX3ZlcmlmaWVkIjp0cnVlLCJleHAiOjE1NTAxODU5MzUsImlhdCI6MTU1MDE4MjMzNSwia
XNzIjoiaHR0cHM6Ly9hY2NvdW50cy5nb29nbGUuY29tIiwic3ViIjoiMTEzNzc0MjY0NDYzMDM4MzIxO
TY0In0.QVjyqpmadTyDZmlX2u3jWd1kJ68YkdwsRZDo-QxSPbxjug4ucLBwAs2QePrcgZ6hhkvdc4UHY
4YF3fz9g7XHULNVIzX5xh02qXEH8dK6PgGndIWcZQzjSYfgO-q-R2oo2hNM5HBBsQN4ARtGK_acG-NGG
WM3CQfahbEjZPAJe_B8M7HfIu_G5jOLZCw2EUcGo8BvEwGcLWB2WqEgRM0-xt5-UPzoa3-FpSPG7DHk7
z9zRUeq6eB__ldb-2o4RciJmjVwHgnYqn3VvlX9oVKEgXpNFhKuYA-mWh5o7BCwhujSMmFoBOh6mbIXF
cyf5UiVqKjpqEbqPGo_AvKvIQ9VTQ"

标头和声明集是 JSON 字符串。解码后，它们将采用以下格式：

{"alg":"RS256","kid":"7d680d8c70d44e947133cbd499ebc1a61c3d5abc","typ":"JWT"}

{
   "aud":"https://example.com",
   "azp":"113774264463038321964",
   "email":"gae-gcp@appspot.gserviceaccount.com",
   "sub":"113774264463038321964",
   "email_verified":true,
   "exp":1550185935,
   "iat":1550182335,
   "iss":"https://accounts.google.com"
  }

附加到发送到推送端点的请求的令牌可具有最长达一个小时的生命周期。

配置 Pub/Sub 以进行推送身份验证

以下示例展示了如何将推送身份验证服务帐号设置为您选择的服务帐号，以及如何向 Google 代管式服务帐号 service-{PROJECT_NUMBER}@gcp-sa-pubsub.iam.gserviceaccount.com 授予 iam.serviceAccountTokenCreator 角色。

控制台

转到 Pub/Sub 订阅页面。

转到“订阅”页面
点击创建订阅。
在订阅 ID 字段中，输入一个名称。
选择主题。
选择推送作为传送类型。
输入端点网址。
选中 Enable authentication（启用身份验证）。
选择服务帐号。
确保 Google 代管式服务帐号 service-{PROJECT_NUMBER}@gcp-sa-pubsub.iam.gserviceaccount.com 在项目的 IAM 信息中心具有 iam.serviceAccountTokenCreator 角色。如果尚未向服务帐号授予角色，请点击 IAM 信息中心内的授予以执行此操作。
可选：输入受众群体。
点击创建。

gcloud

# Configure the push subscription
gcloud pubsub subscriptions (create|update|modify-push-config) ${SUBSCRIPTION} \
 --topic=${TOPIC} \
 --push-endpoint=${PUSH_ENDPOINT_URI} \
 --push-auth-service-account=${SERVICE_ACCOUNT_EMAIL} \
 --push-auth-token-audience=${OPTIONAL_AUDIENCE_OVERRIDE}

# Your Google-managed service account
# `service-{PROJECT_NUMBER}@gcp-sa-pubsub.iam.gserviceaccount.com` needs to have the
# `iam.serviceAccountTokenCreator` role.
PUBSUB_SERVICE_ACCOUNT="service-${PROJECT_NUMBER}@gcp-sa-pubsub.iam.gserviceaccount.com"
gcloud projects add-iam-policy-binding ${PROJECT_ID} \
 --member="serviceAccount:${PUBSUB_SERVICE_ACCOUNT}"\
 --role='roles/iam.serviceAccountTokenCreator'

为推送订阅启用身份验证时，您可能会遇到 permission denied 或 not authorized 错误。如需解决此问题，请为发起订阅创建或更新的主帐号授予服务帐号的 iam.serviceAccounts.actAs 权限。如需了解详情，请参阅“创建推送订阅”中的身份验证。

如果您将经过身份验证的推送订阅与受 Identity-Aware Proxy 保护的 App Engine 应用搭配使用，则必须提供 IAP 客户端 ID 作为推送身份验证令牌受众群体。如需在 App Engine 应用上启用 IAP，请参阅启用 IAP。如需查找 IAP 客户端 ID，请在凭据页面上查找 IAP-App-Engine-app 客户端 ID。

申请

JWT 可用于验证由 Google 签名的声明（包括 email 和 aud 声明）。如需详细了解 Google 的 OAuth 2.0 API 如何用于身份验证和授权，请参阅 OpenID Connect。

可通过两种机制使声明变得有意义。首先，Pub/Sub 要求进行 CreateSubscription、UpdateSubscription 或 ModifyPushConfig 调用的用户或服务帐号具有对推送身份验证服务帐号具有 iam.serviceAccounts.actAs 权限的角色。此类角色的一个示例是 roles/iam.serviceAccountUser 角色。

其次，严格控制对用于为令牌签名的证书的访问。如需创建令牌，Pub/Sub 必须使用单独的签名服务帐号身份（即 Google 代管式服务帐号 service-${PROJECT_NUMBER}@gcp-sa-pubsub.iam.gserviceaccount.com）调用内部 Google 服务。此签名服务帐号必须具有推送身份验证服务帐号（或推送身份验证服务帐号的任何祖先资源（例如项目））的 iam.serviceAccounts.getOpenIdToken 权限或 Service Account Token Creator 角色 (roles/iam.serviceAccountTokenCreator)。

验证令牌

验证 Pub/Sub 发送到推送端点的令牌涉及：

通过使用签名验证检查令牌完整性。
确保令牌中的 email 和 audience 声明与推送订阅配置中设置的值匹配。

以下示例说明了如何对未通过 Identity-Aware Proxy 保护的 App Engine 应用的推送请求进行身份验证。如果您的 App Engine 应用受 IAP 保护，则包含 IAP JWT 的 HTTP 请求标头为 x-goog-iap-jwt-assertion，必须进行相应验证。

协议

请求：

GET https://oauth2.googleapis.com/tokeninfo?id_token={BEARER_TOKEN}

响应：

200 OK

{
    "alg": "RS256",
    "aud": "example.com",
    "azp": "104176025330667568672",
    "email": "{SERVICE_ACCOUNT_NAME}@{YOUR_PROJECT_NAME}.iam.gserviceaccount.com",
    "email_verified": "true",
    "exp": "1555463097",
    "iat": "1555459497",
    "iss": "https://accounts.google.com",
    "kid": "3782d3f0bc89008d9d2c01730f765cfb19d3b70e",
    "sub": "104176025330667568672",
    "typ": "JWT"
}

C#

在尝试此示例之前，请按照《快速入门：使用客户端库》中的 C# 设置说明进行操作。如需了解详情，请参阅 Pub/Sub C# API 参考文档。

        /// <summary>
        /// Extended JWT payload to match the pubsub payload format.
        /// </summary>
        public class PubSubPayload : JsonWebSignature.Payload
        {
            [JsonProperty("email")]
            public string Email { get; set; }
            [JsonProperty("email_verified")]
            public string EmailVerified { get; set; }
        }
        /// <summary>
        /// Handle authenticated push request coming from pubsub.
        /// </summary>
        [HttpPost]
        [Route("/AuthPush")]
        public async Task<IActionResult> AuthPushAsync([FromBody] PushBody body, [FromQuery] string token)
        {
            // Get the Cloud Pub/Sub-generated "Authorization" header.
            string authorizaionHeader = HttpContext.Request.Headers["Authorization"];
            string verificationToken = token ?? body.message.attributes["token"];
            // JWT token comes in `Bearer <JWT>` format substring 7 specifies the position of first JWT char.
            string authToken = authorizaionHeader.StartsWith("Bearer ") ? authorizaionHeader.Substring(7) : null;
            if (verificationToken != _options.VerificationToken || authToken is null)
            {
                return new BadRequestResult();
            }
            // Verify and decode the JWT.
            // Note: For high volume push requests, it would save some network
            // overhead if you verify the tokens offline by decoding them using
            // Google's Public Cert; caching already seen tokens works best when
            // a large volume of messages have prompted a single push server to
            // handle them, in which case they would all share the same token for
            // a limited time window.
            var payload = await JsonWebSignature.VerifySignedTokenAsync<PubSubPayload>(authToken);

            // IMPORTANT: you should validate payload details not covered
            // by signature and audience verification above, including:
            //   - Ensure that `payload.Email` is equal to the expected service
            //     account set up in the push subscription settings.
            //   - Ensure that `payload.Email_verified` is set to true.

            var messageBytes = Convert.FromBase64String(body.message.data);
            string message = System.Text.Encoding.UTF8.GetString(messageBytes);
            s_authenticatedMessages.Add(message);
            return new OkResult();
        }

Go

// receiveMessagesHandler validates authentication token and caches the Pub/Sub
// message received.
func (a *app) receiveMessagesHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method != "POST" {
		http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
		return
	}

	// Verify that the request originates from the application.
	// a.pubsubVerificationToken = os.Getenv("PUBSUB_VERIFICATION_TOKEN")
	if token, ok := r.URL.Query()["token"]; !ok || len(token) != 1 || token[0] != a.pubsubVerificationToken {
		http.Error(w, "Bad token", http.StatusBadRequest)
		return
	}

	// Get the Cloud Pub/Sub-generated JWT in the "Authorization" header.
	authHeader := r.Header.Get("Authorization")
	if authHeader == "" || len(strings.Split(authHeader, " ")) != 2 {
		http.Error(w, "Missing Authorization header", http.StatusBadRequest)
		return
	}
	token := strings.Split(authHeader, " ")[1]
	// Verify and decode the JWT.
	// If you don't need to control the HTTP client used you can use the
	// convenience method idtoken.Validate instead of creating a Validator.
	v, err := idtoken.NewValidator(r.Context(), option.WithHTTPClient(a.defaultHTTPClient))
	if err != nil {
		http.Error(w, "Unable to create Validator", http.StatusBadRequest)
		return
	}
	// Please change http://example.com to match with the value you are
	// providing while creating the subscription.
	payload, err := v.Validate(r.Context(), token, "http://example.com")
	if err != nil {
		http.Error(w, fmt.Sprintf("Invalid Token: %v", err), http.StatusBadRequest)
		return
	}
	if payload.Issuer != "accounts.google.com" && payload.Issuer != "https://accounts.google.com" {
		http.Error(w, "Wrong Issuer", http.StatusBadRequest)
		return
	}

	// IMPORTANT: you should validate claim details not covered by signature
	// and audience verification above, including:
	//   - Ensure that `payload.Claims["email"]` is equal to the expected service
	//     account set up in the push subscription settings.
	//   - Ensure that `payload.Claims["email_verified"]` is set to true.
	if payload.Claims["email"] != "test-service-account-email@example.com" || payload.Claims["email_verified"] != true {
		http.Error(w, "Unexpected email identity", http.StatusBadRequest)
		return
	}

	var pr pushRequest
	if err := json.NewDecoder(r.Body).Decode(&pr); err != nil {
		http.Error(w, fmt.Sprintf("Could not decode body: %v", err), http.StatusBadRequest)
		return
	}

	a.messagesMu.Lock()
	defer a.messagesMu.Unlock()
	// Limit to ten.
	a.messages = append(a.messages, pr.Message.Data)
	if len(a.messages) > maxMessages {
		a.messages = a.messages[len(a.messages)-maxMessages:]
	}

	fmt.Fprint(w, "OK")
}

Java

@WebServlet(value = "/pubsub/authenticated-push")
public class PubSubAuthenticatedPush extends HttpServlet {
  private final String pubsubVerificationToken = System.getenv("PUBSUB_VERIFICATION_TOKEN");
  private final MessageRepository messageRepository;
  private final GoogleIdTokenVerifier verifier =
      new GoogleIdTokenVerifier.Builder(new NetHttpTransport(), new GsonFactory())
          /**
           * Please change example.com to match with value you are providing while creating
           * subscription as provided in @see <a
           * href="https://github.com/GoogleCloudPlatform/java-docs-samples/tree/main/appengine-java8/pubsub">README</a>.
           */
          .setAudience(Collections.singletonList("example.com"))
          .build();
  private final Gson gson = new Gson();

  @Override
  public void doPost(HttpServletRequest req, HttpServletResponse resp)
      throws IOException, ServletException {

    // Verify that the request originates from the application.
    if (req.getParameter("token").compareTo(pubsubVerificationToken) != 0) {
      resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
      return;
    }
    // Get the Cloud Pub/Sub-generated JWT in the "Authorization" header.
    String authorizationHeader = req.getHeader("Authorization");
    if (authorizationHeader == null
        || authorizationHeader.isEmpty()
        || authorizationHeader.split(" ").length != 2) {
      resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
      return;
    }
    String authorization = authorizationHeader.split(" ")[1];

    try {
      // Verify and decode the JWT.
      // Note: For high volume push requests, it would save some network overhead
      // if you verify the tokens offline by decoding them using Google's Public
      // Cert; caching already seen tokens works best when a large volume of
      // messsages have prompted a single push server to handle them, in which
      // case they would all share the same token for a limited time window.
      GoogleIdToken idToken = verifier.verify(authorization);

      GoogleIdToken.Payload payload = idToken.getPayload();
      // IMPORTANT: you should validate claim details not covered by signature
      // and audience verification above, including:
      //   - Ensure that `payload.getEmail()` is equal to the expected service
      //     account set up in the push subscription settings.
      //   - Ensure that `payload.getEmailVerified()` is set to true.

      messageRepository.saveToken(authorization);
      messageRepository.saveClaim(payload.toPrettyString());
      // parse message object from "message" field in the request body json
      // decode message data from base64
      Message message = getMessage(req);
      messageRepository.save(message);
      // 200, 201, 204, 102 status codes are interpreted as success by the Pub/Sub system
      resp.setStatus(102);
      super.doPost(req, resp);
    } catch (Exception e) {
      resp.setStatus(HttpServletResponse.SC_BAD_REQUEST);
    }
  }

  private Message getMessage(HttpServletRequest request) throws IOException {
    String requestBody = request.getReader().lines().collect(Collectors.joining("\n"));
    JsonElement jsonRoot = JsonParser.parseString(requestBody).getAsJsonObject();
    String messageStr = jsonRoot.getAsJsonObject().get("message").toString();
    Message message = gson.fromJson(messageStr, Message.class);
    // decode from base64
    String decoded = decode(message.getData());
    message.setData(decoded);
    return message;
  }

  private String decode(String data) {
    return new String(Base64.getDecoder().decode(data));
  }

  PubSubAuthenticatedPush(MessageRepository messageRepository) {
    this.messageRepository = messageRepository;
  }

  public PubSubAuthenticatedPush() {
    this(MessageRepositoryImpl.getInstance());
  }
}

Node.js

app.post('/pubsub/authenticated-push', jsonBodyParser, async (req, res) => {
  // Verify that the request originates from the application.
  if (req.query.token !== PUBSUB_VERIFICATION_TOKEN) {
    res.status(400).send('Invalid request');
    return;
  }

  // Verify that the push request originates from Cloud Pub/Sub.
  try {
    // Get the Cloud Pub/Sub-generated JWT in the "Authorization" header.
    const bearer = req.header('Authorization');
    const [, token] = bearer.match(/Bearer (.*)/);
    tokens.push(token);

    // Verify and decode the JWT.
    // Note: For high volume push requests, it would save some network
    // overhead if you verify the tokens offline by decoding them using
    // Google's Public Cert; caching already seen tokens works best when
    // a large volume of messages have prompted a single push server to
    // handle them, in which case they would all share the same token for
    // a limited time window.
    const ticket = await authClient.verifyIdToken({
      idToken: token,
      audience: 'example.com',
    });

    const claim = ticket.getPayload();

    // IMPORTANT: you should validate claim details not covered
    // by signature and audience verification above, including:
    //   - Ensure that `claim.email` is equal to the expected service
    //     account set up in the push subscription settings.
    //   - Ensure that `claim.email_verified` is set to true.

    claims.push(claim);
  } catch (e) {
    res.status(400).send('Invalid token');
    return;
  }

  // The message is a unicode string encoded in base64.
  const message = Buffer.from(req.body.message.data, 'base64').toString(
    'utf-8'
  );

  messages.push(message);

  res.status(200).send();
});

Python

@app.route("/push-handlers/receive_messages", methods=["POST"])
def receive_messages_handler():
    # Verify that the request originates from the application.
    if request.args.get("token", "") != current_app.config["PUBSUB_VERIFICATION_TOKEN"]:
        return "Invalid request", 400

    # Verify that the push request originates from Cloud Pub/Sub.
    try:
        # Get the Cloud Pub/Sub-generated JWT in the "Authorization" header.
        bearer_token = request.headers.get("Authorization")
        token = bearer_token.split(" ")[1]
        TOKENS.append(token)

        # Verify and decode the JWT. `verify_oauth2_token` verifies
        # the JWT signature, the `aud` claim, and the `exp` claim.
        # Note: For high volume push requests, it would save some network
        # overhead if you verify the tokens offline by downloading Google's
        # Public Cert and decode them using the `google.auth.jwt` module;
        # caching already seen tokens works best when a large volume of
        # messages have prompted a single push server to handle them, in which
        # case they would all share the same token for a limited time window.
        claim = id_token.verify_oauth2_token(
            token, requests.Request(), audience="example.com"
        )

        # IMPORTANT: you should validate claim details not covered by signature
        # and audience verification above, including:
        #   - Ensure that `claim["email"]` is equal to the expected service
        #     account set up in the push subscription settings.
        #   - Ensure that `claim["email_verified"]` is set to true.

        CLAIMS.append(claim)
    except Exception as e:
        return f"Invalid token: {e}\n", 400

    envelope = json.loads(request.data.decode("utf-8"))
    payload = base64.b64decode(envelope["message"]["data"])
    MESSAGES.append(payload)
    # Returning any 2xx status indicates successful receipt of the message.
    return "OK", 200

Ruby

post "/pubsub/authenticated-push" do
  halt 400 if params[:token] != PUBSUB_VERIFICATION_TOKEN

  begin
    bearer = request.env["HTTP_AUTHORIZATION"]
    token = /Bearer (.*)/.match(bearer)[1]
    claim = Google::Auth::IDTokens.verify_oidc token, aud: "example.com"

    # IMPORTANT: you should validate claim details not covered by signature
    # and audience verification above, including:
    #   - Ensure that `claim["email"]` is equal to the expected service
    #     account set up in the push subscription settings.
    #   - Ensure that `claim["email_verified"]` is set to true.

    claims.push claim
  rescue Google::Auth::IDTokens::VerificationError => e
    puts "VerificationError: #{e.message}"
    halt 400, "Invalid token"
  end

  message = JSON.parse request.body.read
  payload = Base64.decode64 message["message"]["data"]

  messages.push payload
end

如需了解上述代码示例中使用的环境变量 PUBSUB_VERIFICATION_TOKEN，请参阅编写和响应 Pub/Sub 消息。

可在面向网站的 Google 登录指南中找到其他有关如何验证不记名 JWT 的示例。如需详细了解 OpenID 令牌，请参阅 OpenID Connect 指南，包括有助于验证 JWT 的客户端库列表。

从其他 Google Cloud 服务进行身份验证

Cloud Run、App Engine 和 Cloud Functions 通过验证 Pub/Sub 生成的令牌来验证来自 Pub/Sub 的 HTTP 调用。您只需进行一项配置，即向调用方帐号授予必要的 IAM 角色。

如需了解这些服务的不同使用场景，请参阅以下指南和教程：

Cloud Run

从 Pub/Sub 推送触发：您的推送身份验证服务帐号必须具有 roles/run.invoker 角色，并绑定到 Cloud Run 服务才能调用相应的 Cloud Run 服务
教程：将 Pub/Sub 与 Cloud Run 搭配使用

App Engine

编写和响应 Pub/Sub 消息

Cloud Functions

HTTP 触发器：如果您打算将 Pub/Sub 推送请求用作函数的 HTTP 触发器，那么推送身份验证服务帐号必须具有 roles/cloudfunctions.invoker 角色才能调用函数
Google Cloud Pub/Sub 触发器：如果您使用 Pub/Sub 触发器调用函数，系统会自动配置 IAM 角色和权限

注意：在第一代 App Engine 运行时中，向同一项目中 /_ah/push-handlers/.* 形式的端点网址的推送请求被授权为管理员用户。第二代 App Engine 运行时环境不再支持此 ACL 机制。在第二代 App Engine 运行时环境中，将管理员使用的 IAM 角色授予推送订阅配置的推送身份验证服务账号。有关详情，请访问对用户进行身份验证和了解访问权限控制。