mqtt: Add ssl mutual authentication example

Signed-off-by: David Cermak <cermak@espressif.com>

examples/mqtt_ssl_mutual_auth/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.5)
+
+get_filename_component(DEV_ROOT "${CMAKE_CURRENT_SOURCE_DIR}" ABSOLUTE)
+
+set(PROJECT_ROOT "${DEV_ROOT}/")
+
+set(SUBMODULE_ROOT "${DEV_ROOT}/../../../")
+
+set(PROJECT_NAME "mqtt_ssl_mutual_auth")
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+
+set(MAIN_SRCS ${PROJECT_ROOT}/main/app_main.c)
+
+set(EXTRA_COMPONENT_DIRS "${EXTRA_COMPONENT_DIRS} ${SUBMODULE_ROOT}")
+set(BUILD_COMPONENTS "${BUILD_COMPONENTS} espmqtt")
+
+project(${PROJECT_NAME})
+

examples/mqtt_ssl_mutual_auth/Makefile

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+#
+# This is a project Makefile. It is assumed the directory this Makefile resides in is a
+# project subdirectory.
+#
+#
+# This is a project Makefile. It is assumed the directory this Makefile resides in is a
+# project subdirectory.
+#
+PROJECT_NAME := mqtt_ssl_mutual_auth
+EXTRA_COMPONENT_DIRS += $(PROJECT_PATH)/../../../
+
+include $(IDF_PATH)/make/project.mk
+

examples/mqtt_ssl_mutual_auth/README.md

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+# ESPMQTT SSL Sample application
+
+Navigate to the main directory
+
+```
+cd main
+```
+
+Generate a client key and a CSR. When you are generating the CSR, do not use the default values. At a minimum, the CSR must include the Country, Organisation and Common Name fields.
+
+```
+openssl genrsa -out client.key
+openssl req -out client.csr -key client.key -new
+```
+
+Paste the generated CSR in the [Mosquitto test certificate signer](https://test.mosquitto.org/ssl/index.php), click Submit and copy the downloaded `client.crt` in the `main` directory.

examples/mqtt_ssl_mutual_auth/main/Kconfig.projbuild

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+menu "MQTT Application sample"
+
+config WIFI_SSID
+    string "WiFi SSID"
+    default "myssid"
+    help
+        SSID (network name) for the example to connect to.
+
+config WIFI_PASSWORD
+    string "WiFi Password"
+    default "mypassword"
+    help
+        WiFi password (WPA or WPA2) for the example to use.
+
+endmenu

examples/mqtt_ssl_mutual_auth/main/app_main.c

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+#include <stdio.h>
+#include <stdint.h>
+#include <stddef.h>
+#include <string.h>
+#include "esp_wifi.h"
+#include "esp_system.h"
+#include "nvs_flash.h"
+#include "esp_event_loop.h"
+
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/semphr.h"
+#include "freertos/queue.h"
+#include "freertos/event_groups.h"
+
+#include "lwip/sockets.h"
+#include "lwip/dns.h"
+#include "lwip/netdb.h"
+
+#include "esp_log.h"
+#include "mqtt_client.h"
+
+static const char *TAG = "MQTTS_SAMPLE";
+
+static EventGroupHandle_t wifi_event_group;
+const static int CONNECTED_BIT = BIT0;
+
+
+
+static esp_err_t wifi_event_handler(void *ctx, system_event_t *event)
+{
+    switch (event->event_id) {
+        case SYSTEM_EVENT_STA_START:
+            esp_wifi_connect();
+            break;
+        case SYSTEM_EVENT_STA_GOT_IP:
+            xEventGroupSetBits(wifi_event_group, CONNECTED_BIT);
+
+            break;
+        case SYSTEM_EVENT_STA_DISCONNECTED:
+            esp_wifi_connect();
+            xEventGroupClearBits(wifi_event_group, CONNECTED_BIT);
+            break;
+        default:
+            break;
+    }
+    return ESP_OK;
+}
+
+static void wifi_init(void)
+{
+    tcpip_adapter_init();
+    wifi_event_group = xEventGroupCreate();
+    ESP_ERROR_CHECK(esp_event_loop_init(wifi_event_handler, NULL));
+    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
+    ESP_ERROR_CHECK(esp_wifi_init(&cfg));
+    ESP_ERROR_CHECK(esp_wifi_set_storage(WIFI_STORAGE_RAM));
+    wifi_config_t wifi_config = {
+        .sta = {
+            .ssid = CONFIG_WIFI_SSID,
+            .password = CONFIG_WIFI_PASSWORD,
+        },
+    };
+    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
+    ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_STA, &wifi_config));
+    ESP_LOGI(TAG, "start the WIFI SSID:[%s] password:[%s]", CONFIG_WIFI_SSID, "******");
+    ESP_ERROR_CHECK(esp_wifi_start());
+    ESP_LOGI(TAG, "Waiting for wifi");
+    xEventGroupWaitBits(wifi_event_group, CONNECTED_BIT, false, true, portMAX_DELAY);
+}
+
+extern const uint8_t client_cert_pem_start[] asm("_binary_client_crt_start");
+extern const uint8_t client_cert_pem_end[] asm("_binary_client_crt_end");
+extern const uint8_t client_key_pem_start[] asm("_binary_client_key_start");
+extern const uint8_t client_key_pem_end[] asm("_binary_client_key_end");
+
+static esp_err_t mqtt_event_handler(esp_mqtt_event_handle_t event)
+{
+    esp_mqtt_client_handle_t client = event->client;
+    int msg_id;
+    // your_context_t *context = event->context;
+    switch (event->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", event->msg_id);
+            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");
+            break;
+    }
+    return ESP_OK;
+}
+
+static void mqtt_app_start(void)
+{
+    const esp_mqtt_client_config_t mqtt_cfg = {
+        .uri = "mqtts://test.mosquitto.org:8884",
+        .event_handle = mqtt_event_handler,
+        .client_cert_pem = (const char *)client_cert_pem_start,
+        .client_key_pem = (const char *)client_key_pem_start,
+    };
+
+    ESP_LOGI(TAG, "[APP] Free memory: %d bytes", esp_get_free_heap_size());
+    esp_mqtt_client_handle_t client = esp_mqtt_client_init(&mqtt_cfg);
+    esp_mqtt_client_start(client);
+}
+
+void app_main()
+{
+    ESP_LOGI(TAG, "[APP] Startup..");
+    ESP_LOGI(TAG, "[APP] Free memory: %d 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("MQTT_CLIENT", ESP_LOG_VERBOSE);
+    esp_log_level_set("TRANSPORT_TCP", ESP_LOG_VERBOSE);
+    esp_log_level_set("TRANSPORT_SSL", ESP_LOG_VERBOSE);
+    esp_log_level_set("TRANSPORT", ESP_LOG_VERBOSE);
+    esp_log_level_set("OUTBOX", ESP_LOG_VERBOSE);
+
+    nvs_flash_init();
+    wifi_init();
+    mqtt_app_start();
+
+}

examples/mqtt_ssl_mutual_auth/main/component.mk

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+COMPONENT_EMBED_TXTFILES := client.crt client.key