在 Javascript 中使用 MQTT 连接到 Azure IotHub

Question

尝试使用 MQTT.js (https://github.com/mqttjs/MQTT.js) 连接到 Azure IotHub 时，我总是返回 Connection refused: Not authorized。

SAS 密码是使用 Microsoft Device Explorer (https://github.com/Azure/azure-iot-sdk-csharp/tree/master/tools/DeviceExplorer) 生成的，因此提供正确的 read/write 连接详细信息以及未来的到期日期，我假设它是正确且有效的。

我还要求启用 TLS/SSL（根据 Microsoft Azure 文档：https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-mqtt-support#tlsssl-configuration) via rejectUnauthorized: false (as explained in the documentation for MQTT.js at https://github.com/mqttjs/MQTT.js#client）。

如何使用第三方 MQTT 库和 SAS 令牌通过 Javascript 进行连接？

这是 Javascript 代码的片段：

var MQTT = require("async-mqtt");

const deviceId = "<PUT_SOMETHING_HERE>";
const iotHubName = "<PUT_SOMETHING_HERE>";

const url = `${iotHubName}.azure-devices.net/${deviceId}/api-version=2016-11-14`;
const iotHubTopic = `devices/${deviceId}/messages/events/`

var client = MQTT.connect(`mqtts://${url}:8883`, {
  username: url,
  password: `SharedAccessSignature sr=${iotHubName}.azure-devices.net&sig=<COMBINATION_OF_PASSWORDS_URL_ENCODED>&se=<EPOCH_EXPIRY>&skn=<ACCESS_POLICY_NAME>`,
  rejectUnauthorized: false, // https://github.com/mqttjs/MQTT.js#client
});

// this is code from the MQTT.js example, but I don't even reach it
async function doStuff() {

    console.log("Starting");
    try {
        await client.publish(iotHubTopic, "It works!");
        // This line doesn't run until the server responds to the publish
        await client.end();
        // This line doesn't run until the client has disconnected without error
        console.log("Done");
    } catch (e){
        // Do something about it!
        console.log("Error while sending a message...");
        console.log(e.stack);
        process.exit();
    }
}

const ceremony = () => {
  return new Promise((resolve, reject) => {
      client.on("connect", doStuff);
      return resolve();
    })
    .then((stuff) => {
      console.log("Done?", stuff);
    })
    .catch((err) => {
      console.log("Err...", err);
      process.exit();
    });
}

ceremony();

输出是这样的：

Done? undefined
events.js:183
      throw er; // Unhandled 'error' event
      ^

Error: Connection refused: Not authorized
    at MqttClient._handleConnack (<PATH_TO_THE_JS_PROJECT>/node_modules/mqtt/lib/client.js:896:15)
    at MqttClient._handlePacket (<PATH_TO_THE_JS_PROJECT>/node_modules/mqtt/lib/client.js:332:12)
    at work (<PATH_TO_THE_JS_PROJECT>/node_modules/mqtt/lib/client.js:274:12)
    at Writable.writable._write (<PATH_TO_THE_JS_PROJECT>/node_modules/mqtt/lib/client.js:284:5)
    at doWrite (<PATH_TO_THE_JS_PROJECT>/node_modules/mqtt/node_modules/readable-stream/lib/_stream_writable.js:428:64)
    at writeOrBuffer (<PATH_TO_THE_JS_PROJECT>/node_modules/mqtt/node_modules/readable-stream/lib/_stream_writable.js:417:5)
    at Writable.write (<PATH_TO_THE_JS_PROJECT>/node_modules/mqtt/node_modules/readable-stream/lib/_stream_writable.js:334:11)
    at TLSSocket.ondata (_stream_readable.js:639:20)
    at emitOne (events.js:116:13)
    at TLSSocket.emit (events.js:211:7)

Answer 1

是的，Azure IoT Hub 支持 MQTT，您可以使用 MQTT 协议直接与 IoT Hub 连接，publish/subscribe 主题作为 send/receive 消息，带有记录的主题名称和主题过滤器。我修改了上面的代码，可以正常使用了。

var MQTT = require("async-mqtt");

const deviceId = "{the device name}";
const iotHubName = "{your iot hub name}";
const userName = `${iotHubName}.azure-devices.net/${deviceId}/api-version=2016-11-14`;
const iotHubTopic = `devices/${deviceId}/messages/events/`;

var client = MQTT.connect(`mqtts://${iotHubName}.azure-devices.net:8883`, {
  keepalive: 10,
  clientId: deviceId,
  protocolId: 'MQTT',
  clean: false,
  protocolVersion: 4,
  reconnectPeriod: 1000,
  connectTimeout: 30 * 1000,
  username: userName,
  password: "{SAS Token}",
  rejectUnauthorized: false, 
});

// this is code from the MQTT.js example, but I don't even reach it
async function doStuff() {

    console.log("Starting");
    try {
        await client.publish(iotHubTopic, "It works!");
        // This line doesn't run until the server responds to the publish
        await client.end();
        // This line doesn't run until the client has disconnected without error
        console.log("Done");
    } catch (e){
        // Do something about it!
        console.log("Error while sending a message...");
        console.log(e.stack);
        process.exit();
    }
}

const ceremony = () => {
  return new Promise((resolve, reject) => {
      client.on("connect", doStuff);
      return resolve();
    })
    .then((stuff) => {
      console.log("Done?", stuff);
    })
    .catch((err) => {
      console.log("Err...", err);
      process.exit();
    });
}

ceremony();

代码中需要注意的是：

在 IoT 中心使用 DEVICE ID 作为连接选项中的 clientId；
使用mqtts协议；
对于用户名选项，使用{iothubhostname}/{device_id}/api-version=2016-11-14，其中{iothubhostname } 是 IoT 中心的完整 CName。
对于密码字段，使用 SAS 令牌。您可以使用 Device Explorer 获取 SAS 令牌。 SAS 令牌 必须使用涉及权限的策略生成 ："registry write"、"service connect" 和 "device connect"（少于这三个的组合可能工作，但提供 "registry write" 肯定是不够的）。

Answer 2

我遇到了同样的问题。尝试半小时后，我才知道我的一位同事在 Iothub 上禁用了我的设备。

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