azure - 使用 MQTT 通过 Websockets(端口 443)而不是端口 8883 将 ESP32 连接到 Azure Iot Hub

Question

我目前正在做一个实习项目，我希望将 MQTT 消息从 ESP32 发送到 Azure Iot Hub。为了在 ESP32 和 Azure Iot Hub 之间建立初始连接，我按照 ESP32 Iot Hub Azure sdk for C example 中的示例进行操作。它能够将遥测数据发送到我正在使用物联网中心浏览器进行监控的物联网中心。但由于该项目计划在公共(public)场所推广，8883端口很可能被封锁。 Documentation表示 IoT Hub 支持 TCP 端口 443 上基于 websocket 的 MQTT。

我的问题是如何更改端口和客户端配置才能使用端口 443？我目前正在使用 azure sdk for c arduino 库(如上面的链接所示)，并在 platformio IDE 上构建 esp32。

主要代码如下

// Copyright (c) Microsoft Corporation. All rights reserved.
// SPDX-License-Identifier: MIT

/*
 * This is an Arduino-based Azure IoT Hub sample for ESPRESSIF ESP32 boards.
 * It uses our Azure Embedded SDK for C to help interact with Azure IoT.
 * For reference, please visit https://github.com/azure/azure-sdk-for-c.
 *
 * To connect and work with Azure IoT Hub you need an MQTT client, connecting, subscribing
 * and publishing to specific topics to use the messaging features of the hub.
 * Our azure-sdk-for-c is an MQTT client support library, helping composing and parsing the
 * MQTT topic names and messages exchanged with the Azure IoT Hub.
 *
 * This sample performs the following tasks:
 * - Synchronize the device clock with a NTP server;
 * - Initialize our "az_iot_hub_client" (struct for data, part of our azure-sdk-for-c);
 * - Initialize the MQTT client (here we use ESPRESSIF's esp_mqtt_client, which also handle the tcp
 * connection and TLS);
 * - Connect the MQTT client (using server-certificate validation, SAS-tokens for client
 * authentication);
 * - Periodically send telemetry data to the Azure IoT Hub.
 *
 * To properly connect to your Azure IoT Hub, please fill the information in the `iot_configs.h`
 * file.
 */

// C99 libraries
#include <cstdlib>
#include <string.h>
#include <time.h>

// Libraries for MQTT client and WiFi connection
#include <WiFi.h>
#include <mqtt_client.h>

// Azure IoT SDK for C includes
#include <az_core.h>
#include <az_iot.h>
#include <azure_ca.h>

// Additional sample headers
#include "AzIoTSasToken.h"
#include "SerialLogger.h"
#include "iot_configs.h"

// When developing for your own Arduino-based platform,
// please follow the format '(ard;<platform>)'.
#define AZURE_SDK_CLIENT_USER_AGENT "c%2F" AZ_SDK_VERSION_STRING "(ard;esp32)"

// Utility macros and defines
#define sizeofarray(a) (sizeof(a) / sizeof(a[0]))
#define NTP_SERVERS "pool.ntp.org", "time.nist.gov"
#define MQTT_QOS1 1
#define DO_NOT_RETAIN_MSG 0
#define SAS_TOKEN_DURATION_IN_MINUTES 60
#define UNIX_TIME_NOV_13_2017 1510592825

#define PST_TIME_ZONE -8
#define PST_TIME_ZONE_DAYLIGHT_SAVINGS_DIFF 1

#define GMT_OFFSET_SECS (PST_TIME_ZONE * 3600)
#define GMT_OFFSET_SECS_DST ((PST_TIME_ZONE + PST_TIME_ZONE_DAYLIGHT_SAVINGS_DIFF) * 3600)

// Translate iot_configs.h defines into variables used by the sample
static const char* ssid = IOT_CONFIG_WIFI_SSID;
static const char* password = IOT_CONFIG_WIFI_PASSWORD;
static const char* host = IOT_CONFIG_IOTHUB_FQDN;
static const char* mqtt_broker_uri = "mqtts://" IOT_CONFIG_IOTHUB_FQDN;
static const char* device_id = IOT_CONFIG_DEVICE_ID;
static const int mqtt_port = AZ_IOT_DEFAULT_MQTT_CONNECT_PORT;
// static const int mqtt_port = 443;

// Memory allocated for the sample's variables and structures.
static esp_mqtt_client_handle_t mqtt_client;
static az_iot_hub_client client;

static char mqtt_client_id[128];
static char mqtt_username[128];
static char mqtt_password[200]; 
static uint8_t sas_signature_buffer[256];
static unsigned long next_telemetry_send_time_ms = 0;
static char telemetry_topic[128];
static uint32_t telemetry_send_count = 0;
static String telemetry_payload = "{}";

#define INCOMING_DATA_BUFFER_SIZE 128
static char incoming_data[INCOMING_DATA_BUFFER_SIZE];

// Auxiliary functions
#ifndef IOT_CONFIG_USE_X509_CERT
static AzIoTSasToken sasToken(
    &client,
    AZ_SPAN_FROM_STR(IOT_CONFIG_DEVICE_KEY),
    AZ_SPAN_FROM_BUFFER(sas_signature_buffer),
    AZ_SPAN_FROM_BUFFER(mqtt_password));
#endif // IOT_CONFIG_USE_X509_CERT

static void connectToWiFi()
{
  Logger.Info("Connecting to WIFI SSID " + String(ssid));

  WiFi.mode(WIFI_STA);
  WiFi.disconnect();
  delay(100);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");

  Logger.Info("WiFi connected, IP address: " + WiFi.localIP().toString());
}

static void initializeTime()
{
  Logger.Info("Setting time using SNTP");

  configTime(GMT_OFFSET_SECS, GMT_OFFSET_SECS_DST, NTP_SERVERS);
  time_t now = time(NULL);
  while (now < UNIX_TIME_NOV_13_2017)
  {
    delay(500);
    Serial.print(".");
    now = time(nullptr);
  }
  Serial.println("");
  Logger.Info("Time initialized!");
}

void receivedCallback(char* topic, byte* payload, unsigned int length)
{
  Logger.Info("Received [");
  Logger.Info(topic);
  Logger.Info("]: ");
  for (int i = 0; i < length; i++)
  {
    Serial.print((char)payload[i]);
  }
  Serial.println("");
}

static esp_err_t mqtt_event_handler(esp_mqtt_event_handle_t event)
{
  switch (event->event_id)
  {
    int i, r;

    case MQTT_EVENT_ERROR:
      Logger.Info("MQTT event MQTT_EVENT_ERROR");
      break;
    case MQTT_EVENT_CONNECTED:
      Logger.Info("MQTT event MQTT_EVENT_CONNECTED");

      r = esp_mqtt_client_subscribe(mqtt_client, AZ_IOT_HUB_CLIENT_C2D_SUBSCRIBE_TOPIC, 1);
      if (r == -1)
      {
        Logger.Error("Could not subscribe for cloud-to-device messages.");
      }
      else
      {
        Logger.Info("Subscribed for cloud-to-device messages; message id:" + String(r));
      }

      break;
    case MQTT_EVENT_DISCONNECTED:
      Logger.Info("MQTT event MQTT_EVENT_DISCONNECTED");
      break;
    case MQTT_EVENT_SUBSCRIBED:
      Logger.Info("MQTT event MQTT_EVENT_SUBSCRIBED");
      break;
    case MQTT_EVENT_UNSUBSCRIBED:
      Logger.Info("MQTT event MQTT_EVENT_UNSUBSCRIBED");
      break;
    case MQTT_EVENT_PUBLISHED:
      Logger.Info("MQTT event MQTT_EVENT_PUBLISHED");
      break;
    case MQTT_EVENT_DATA:
      Logger.Info("MQTT event MQTT_EVENT_DATA");

      for (i = 0; i < (INCOMING_DATA_BUFFER_SIZE - 1) && i < event->topic_len; i++)
      {
        incoming_data[i] = event->topic[i];
      }
      incoming_data[i] = '\0';
      Logger.Info("Topic: " + String(incoming_data));

      for (i = 0; i < (INCOMING_DATA_BUFFER_SIZE - 1) && i < event->data_len; i++)
      {
        incoming_data[i] = event->data[i];
      }
      incoming_data[i] = '\0';
      Logger.Info("Data: " + String(incoming_data));

      break;
    case MQTT_EVENT_BEFORE_CONNECT:
      Logger.Info("MQTT event MQTT_EVENT_BEFORE_CONNECT");
      break;
    default:
      Logger.Error("MQTT event UNKNOWN");
      break;
  }

  return ESP_OK;
}

static void initializeIoTHubClient()
{
  az_iot_hub_client_options options = az_iot_hub_client_options_default();
  options.user_agent = AZ_SPAN_FROM_STR(AZURE_SDK_CLIENT_USER_AGENT);

  if (az_result_failed(az_iot_hub_client_init(
          &client,
          az_span_create((uint8_t*)host, strlen(host)),
          az_span_create((uint8_t*)device_id, strlen(device_id)),
          &options)))
  {
    Logger.Error("Failed initializing Azure IoT Hub client");
    return;
  }

  size_t client_id_length;
  if (az_result_failed(az_iot_hub_client_get_client_id(
          &client, mqtt_client_id, sizeof(mqtt_client_id) - 1, &client_id_length)))
  {
    Logger.Error("Failed getting client id");
    return;
  }

  if (az_result_failed(az_iot_hub_client_get_user_name(
          &client, mqtt_username, sizeofarray(mqtt_username), NULL)))
  {
    Logger.Error("Failed to get MQTT clientId, return code");
    return;
  }

  Logger.Info("Client ID: " + String(mqtt_client_id));
  Logger.Info("Username: " + String(mqtt_username));
}

static int initializeMqttClient()
{
#ifndef IOT_CONFIG_USE_X509_CERT
  if (sasToken.Generate(SAS_TOKEN_DURATION_IN_MINUTES) != 0)
  {
    Logger.Error("Failed generating SAS token");
    return 1;
  }
#endif

  esp_mqtt_client_config_t mqtt_config;
  memset(&mqtt_config, 0, sizeof(mqtt_config));
  mqtt_config.uri = mqtt_broker_uri;
  mqtt_config.port = mqtt_port;
  mqtt_config.client_id = mqtt_client_id;
  mqtt_config.username = mqtt_username;
  

#ifdef IOT_CONFIG_USE_X509_CERT
  Logger.Info("MQTT client using X509 Certificate authentication");
  mqtt_config.client_cert_pem = IOT_CONFIG_DEVICE_CERT;
  mqtt_config.client_key_pem = IOT_CONFIG_DEVICE_CERT_PRIVATE_KEY;
#else // Using SAS key
  mqtt_config.password = (const char*)az_span_ptr(sasToken.Get());
#endif

  mqtt_config.keepalive = 30;
  mqtt_config.disable_clean_session = 0;
  mqtt_config.disable_auto_reconnect = false;
  mqtt_config.event_handle = mqtt_event_handler;
  mqtt_config.user_context = NULL;
  mqtt_config.cert_pem = (const char*)ca_pem;

  mqtt_client = esp_mqtt_client_init(&mqtt_config);

  if (mqtt_client == NULL)
  {
    Logger.Error("Failed creating mqtt client");
    return 1;
  }

  esp_err_t start_result = esp_mqtt_client_start(mqtt_client);

  if (start_result != ESP_OK)
  {
    Logger.Error("Could not start mqtt client; error code:" + start_result);
    return 1;
  }
  else
  {
    Logger.Info("MQTT client started");
    return 0;
  }
}

/*
 * @brief           Gets the number of seconds since UNIX epoch until now.
 * @return uint32_t Number of seconds.
 */
static uint32_t getEpochTimeInSecs() { return (uint32_t)time(NULL); }

static void establishConnection()
{
  connectToWiFi();
  initializeTime();
  initializeIoTHubClient();
  (void)initializeMqttClient();
}

static void generateTelemetryPayload()
{
  // You can generate the JSON using any lib you want. Here we're showing how to do it manually, for simplicity.
  // This sample shows how to generate the payload using a syntax closer to regular delevelopment for Arduino, with
  // String type instead of az_span as it might be done in other samples. Using az_span has the advantage of reusing the 
  // same char buffer instead of dynamically allocating memory each time, as it is done by using the String type below.
  telemetry_payload = "{ \"msgCount\": " + String(telemetry_send_count++) + " }";
}

static void sendTelemetry()
{
  Logger.Info("Sending telemetry ...");

  // The topic could be obtained just once during setup,
  // however if properties are used the topic need to be generated again to reflect the
  // current values of the properties.
  if (az_result_failed(az_iot_hub_client_telemetry_get_publish_topic(
          &client, NULL, telemetry_topic, sizeof(telemetry_topic), NULL)))
  {
    Logger.Error("Failed az_iot_hub_client_telemetry_get_publish_topic");
    return;
  }

  generateTelemetryPayload();

  if (esp_mqtt_client_publish(
          mqtt_client,
          telemetry_topic,
          (const char*)telemetry_payload.c_str(),
          telemetry_payload.length(),
          MQTT_QOS1,
          DO_NOT_RETAIN_MSG)
      == 0)
  {
    Logger.Error("Failed publishing");
  }
  else
  {
    Logger.Info("Message published successfully");
  }
}

// Arduino setup and loop main functions.

void setup() { establishConnection();
Serial.begin(115200);
 }

void loop()
{
  if (WiFi.status() != WL_CONNECTED)
  {
    connectToWiFi();
  }
#ifndef IOT_CONFIG_USE_X509_CERT
  else if (sasToken.IsExpired())
  {
    Logger.Info("SAS token expired; reconnecting with a new one.");
    (void)esp_mqtt_client_destroy(mqtt_client);
    initializeMqttClient();
  }
#endif
  else if (millis() > next_telemetry_send_time_ms)
  {
    sendTelemetry();
    next_telemetry_send_time_ms = millis() + TELEMETRY_FREQUENCY_MILLISECS;
  }
}

Answer 1

将代理 Uri 更改为以 wss:// 开头，而不是 mqtts://