esp-idf/examples/protocols/mqtt/main/app_main.c

/*
 * SPDX-FileCopyrightText: 2025 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Unlicense OR CC0-1.0
 */
/* MQTT over TLS Example

   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/

#include <inttypes.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>

#include "esp_event.h"
#include "esp_log.h"
#include "esp_netif.h"
#include "esp_system.h"
#include "nvs_flash.h"
#include "sdkconfig.h"

#include "protocol_examples_common.h"

#include "esp_crt_bundle.h"
#include "mqtt_client.h"

static const char *TAG = "mqtts_example";

#if CONFIG_EXAMPLE_BROKER_CERTIFICATE_OVERRIDDEN
static const char cert_override_pem[] =
    "-----BEGIN CERTIFICATE-----\n"
    CONFIG_EXAMPLE_BROKER_CERTIFICATE_OVERRIDE "\n"
    "-----END CERTIFICATE-----";
#endif

#if CONFIG_EXAMPLE_CERT_VALIDATE_MOSQUITTO_CA
/* Embedded Mosquitto CA certificate for test.mosquitto.org:8883 */
extern const uint8_t mosquitto_org_crt_start[] asm("_binary_mosquitto_org_crt_start");
extern const uint8_t mosquitto_org_crt_end[] asm("_binary_mosquitto_org_crt_end");
#endif

/*
 * @brief Event handler registered to receive MQTT events
 *
 *  This function is called by the MQTT client event loop.
 *
 * @param handler_args user data registered to the event.
 * @param base Event base for the handler(always MQTT Base in this example).
 * @param event_id The id for the received event.
 * @param event_data The data for the event, esp_mqtt_event_handle_t.
 */
static void mqtt_event_handler(void *handler_args, esp_event_base_t base, int32_t event_id, void *event_data)
{
    ESP_LOGD(TAG, "Event dispatched from event loop base=%s, event_id=%" PRIi32, base, event_id);
    esp_mqtt_event_handle_t event = event_data;
    esp_mqtt_client_handle_t client = event->client;
    int msg_id;
    switch ((esp_mqtt_event_id_t)event_id) {
    case MQTT_EVENT_CONNECTED:
        ESP_LOGI(TAG, "MQTT_EVENT_CONNECTED");
        msg_id = esp_mqtt_client_subscribe(client, "topic/qos0", 0);
        ESP_LOGI(TAG, "sent subscribe successful, msg_id=%d", msg_id);

        msg_id = esp_mqtt_client_subscribe(client, "topic/qos1", 1);
        ESP_LOGI(TAG, "sent subscribe successful, msg_id=%d", msg_id);

        msg_id = esp_mqtt_client_unsubscribe(client, "topic/qos1");
        ESP_LOGI(TAG, "sent unsubscribe successful, msg_id=%d", msg_id);
        break;
    case MQTT_EVENT_DISCONNECTED:
        ESP_LOGI(TAG, "MQTT_EVENT_DISCONNECTED");
        break;

    case MQTT_EVENT_SUBSCRIBED:
        ESP_LOGI(TAG, "MQTT_EVENT_SUBSCRIBED, msg_id=%d, return code=0x%02x ", event->msg_id, (uint8_t)*event->data);
        msg_id = esp_mqtt_client_publish(client, "topic/qos0", "data", 0, 0, 0);
        ESP_LOGI(TAG, "sent publish successful, msg_id=%d", msg_id);
        break;
    case MQTT_EVENT_UNSUBSCRIBED:
        ESP_LOGI(TAG, "MQTT_EVENT_UNSUBSCRIBED, msg_id=%d", event->msg_id);
        break;
    case MQTT_EVENT_PUBLISHED:
        ESP_LOGI(TAG, "MQTT_EVENT_PUBLISHED, msg_id=%d", event->msg_id);
        break;
    case MQTT_EVENT_DATA:
        ESP_LOGI(TAG, "MQTT_EVENT_DATA");
        printf("TOPIC=%.*s\r\n", event->topic_len, event->topic);
        printf("DATA=%.*s\r\n", event->data_len, event->data);
        break;
    case MQTT_EVENT_ERROR:
        ESP_LOGI(TAG, "MQTT_EVENT_ERROR");
        if (event->error_handle->error_type == MQTT_ERROR_TYPE_TCP_TRANSPORT) {
            ESP_LOGI(TAG, "Last error code reported from esp-tls: 0x%x", event->error_handle->esp_tls_last_esp_err);
            ESP_LOGI(TAG, "Last tls stack error number: 0x%x", event->error_handle->esp_tls_stack_err);
            ESP_LOGI(TAG, "Last captured errno : %d (%s)", event->error_handle->esp_transport_sock_errno,
                     strerror(event->error_handle->esp_transport_sock_errno));
        } else if (event->error_handle->error_type == MQTT_ERROR_TYPE_CONNECTION_REFUSED) {
            ESP_LOGI(TAG, "Connection refused error: 0x%x", event->error_handle->connect_return_code);
        } else {
            ESP_LOGW(TAG, "Unknown error type: 0x%x", event->error_handle->error_type);
        }
        break;
    default:
        ESP_LOGI(TAG, "Other event id:%d", event->event_id);
        break;
    }
}

static void mqtt_app_start(void)
{
    const esp_mqtt_client_config_t mqtt_cfg = {
        .broker = {
            .address.uri = CONFIG_EXAMPLE_MQTT_BROKER_URI,
#if CONFIG_EXAMPLE_BROKER_CERTIFICATE_OVERRIDDEN
            .verification.certificate = cert_override_pem,
#elif CONFIG_EXAMPLE_CERT_VALIDATE_MOSQUITTO_CA
            .verification.certificate = (const char *)mosquitto_org_crt_start,
#else
            .verification.crt_bundle_attach = esp_crt_bundle_attach, /* Use built-in certificate bundle */
#endif
        },
    };

    ESP_LOGI(TAG, "[APP] Free memory: %" PRIu32 " bytes", esp_get_free_heap_size());
    esp_mqtt_client_handle_t client = esp_mqtt_client_init(&mqtt_cfg);
    /* The last argument may be used to pass data to the event handler, in this example mqtt_event_handler */
    esp_mqtt_client_register_event(client, ESP_EVENT_ANY_ID, mqtt_event_handler, NULL);
    esp_mqtt_client_start(client);
}

void app_main(void)
{
    ESP_LOGI(TAG, "[APP] Startup..");
    ESP_LOGI(TAG, "[APP] Free memory: %" PRIu32 " bytes", esp_get_free_heap_size());
    ESP_LOGI(TAG, "[APP] IDF version: %s", esp_get_idf_version());

    esp_log_level_set("*", ESP_LOG_INFO);
    esp_log_level_set("esp-tls", ESP_LOG_VERBOSE);
    esp_log_level_set("mqtt_client", ESP_LOG_VERBOSE);
    esp_log_level_set("mqtt_example", ESP_LOG_VERBOSE);
    esp_log_level_set("transport_base", ESP_LOG_VERBOSE);
    esp_log_level_set("transport", ESP_LOG_VERBOSE);
    esp_log_level_set("outbox", ESP_LOG_VERBOSE);

    ESP_ERROR_CHECK(nvs_flash_init());
    ESP_ERROR_CHECK(esp_netif_init());
    ESP_ERROR_CHECK(esp_event_loop_create_default());

    /* This helper function configures Wi-Fi or Ethernet, as selected in menuconfig.
     * Read "Establishing Wi-Fi or Ethernet Connection" section in
     * examples/protocols/README.md for more information about this function.
     */
    ESP_ERROR_CHECK(example_connect());

    mqtt_app_start();
}