minimal support for OTA updates

.gitignore

@@ -1,3 +1,7 @@
 build
 sdkconfig
 sdkconfig.old
+
+# Used during development to test OTA
+# See https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/system.html
+version.txt

main/CMakeLists.txt

@@ -1,2 +1,2 @@
-idf_component_register(SRCS "main.c" "tic.c" "wifi.c" "mqtt.c" "sntp.c" "common.c" "libteleinfo.cpp" "libteleinfo/src/LibTeleinfo.cpp"
+idf_component_register(SRCS "main.c" "tic.c" "wifi.c" "mqtt.c" "sntp.c" "common.c" "ota.c" "libteleinfo.cpp" "libteleinfo/src/LibTeleinfo.cpp"
                     INCLUDE_DIRS ".")

main/common.c

@@ -1,2 +1,20 @@
 #include "common.h"
 volatile EventGroupHandle_t services_event_group;
+
+char* get_nvs_string(nvs_handle_t nvs, char* key) {
+    size_t required_size;
+    esp_err_t err = nvs_get_str(nvs, key, NULL, &required_size);
+    if (err != ESP_OK) {
+        return NULL;
+    }
+    char* value = malloc(required_size);
+    if (!value) {
+        return NULL;
+    }
+    err = nvs_get_str(nvs, key, value, &required_size);
+    if (err != ESP_OK) {
+        free(value);
+        return NULL;
+    }
+    return value;
+}

main/common.h

@@ -4,12 +4,15 @@
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "freertos/event_groups.h"
+#include "nvs_flash.h"
+#include "nvs.h"
 
 #define WIFI_CONNECTED_BIT BIT0
 #define MQTT_CONNECTED_BIT BIT1
 #define TIME_SYNC_BIT BIT2
 
 extern volatile EventGroupHandle_t services_event_group;
+char* get_nvs_string(nvs_handle_t nvs, char* key);
 
 #define WAIT_FOR(flags) while ((xEventGroupWaitBits(services_event_group, flags, pdFALSE, pdTRUE, portMAX_DELAY) & (flags)) != (flags)) {}
 

main/main.c

@@ -14,12 +14,17 @@
 #include "mqtt.h"
 #include "sntp.h"
 #include "common.h"
+#include "esp_ota_ops.h"
+#include "ota.h"
 
 // Embedded via component.mk
 extern const uint8_t cacert_pem_start[]   asm("_binary_cacert_pem_start");
 extern const uint8_t cacert_pem_end[]   asm("_binary_cacert_pem_end");
 
 void app_main(void) {
+    const esp_app_desc_t* current = esp_ota_get_app_description();
+    ESP_LOGI("main", "Currently running %s version %s", current->project_name, current->version);
+
     // NVS is used to store wifi credentials. So, we need to initialize it first.
     ESP_ERROR_CHECK(nvs_flash_init());
 

main/mqtt.c

@@ -8,8 +8,6 @@
 #include "nvs_flash.h"
 #include "esp_event.h"
 #include "esp_netif.h"
-#include "nvs_flash.h"
-#include "nvs.h"
 #include "esp_log.h"
 #include "mqtt_client.h"
 #include "esp_tls.h"
@@ -119,24 +117,6 @@ void mqtt_event_handler(void *handler_args, esp_event_base_t base, int32_t event
     mqtt_event_handler_cb(event_data);
 }
 
-char* get_nvs_string(nvs_handle_t nvs, char* key) {
-    size_t required_size;
-    esp_err_t err = nvs_get_str(nvs, key, NULL, &required_size);
-    if (err != ESP_OK) {
-        return NULL;
-    }
-    char* value = malloc(required_size);
-    if (!value) {
-        return NULL;
-    }
-    err = nvs_get_str(nvs, key, value, &required_size);
-    if (err != ESP_OK) {
-        free(value);
-        return NULL;
-    }
-    return value;
-}
-
 void mqtt_init(void) {
     nvs_handle_t nvs;
     esp_err_t err = nvs_open("mqtt", NVS_READONLY, &nvs);

main/ota.c

@@ -0,0 +1,94 @@
+#include <string.h>
+#include "freertos/FreeRTOS.h"
+#include "esp_log.h"
+#include "esp_https_ota.h"
+#include "esp_ota_ops.h"
+#include "ota.h"
+#include "nvs_flash.h"
+#include "nvs.h"
+#include "common.h"
+
+static const char *OTA_LOGGER = "ota_update";
+
+// Embedded via component.mk
+extern const uint8_t cacert_pem_start[]   asm("_binary_cacert_pem_start");
+extern const uint8_t cacert_pem_end[]   asm("_binary_cacert_pem_end");
+
+esp_err_t do_firmware_upgrade(char* firmware_url) {
+    esp_http_client_config_t config = {
+        .url = firmware_url,
+        .cert_pem = (char *)cacert_pem_start,
+    };
+
+    esp_https_ota_config_t ota_config = {
+        // Can be enabled in an upcoming version of the Espressif SDK
+        // to save some memory.
+        // Requires CONFIG_MBEDTLS_SSL_IN_CONTENT_LEN=4096 in sdkconfig.
+        //
+        //.partial_http_download = true,
+        //.max_http_request_size = 4096,
+        .http_config = &config,
+    };
+
+    esp_https_ota_handle_t https_ota_handle = NULL;
+    esp_err_t err = esp_https_ota_begin(&ota_config, &https_ota_handle);
+    if (https_ota_handle == NULL) {
+        return ESP_FAIL;
+    }
+
+    while (1) {
+        err = esp_https_ota_perform(https_ota_handle);
+        if (err != ESP_ERR_HTTPS_OTA_IN_PROGRESS) {
+            break;
+        }
+    }
+
+    if (err != ESP_OK) {
+        esp_https_ota_abort(https_ota_handle);
+        return err;
+    }
+
+    esp_err_t ota_finish_err = esp_https_ota_finish(https_ota_handle);
+    if (ota_finish_err != ESP_OK) {
+        return ota_finish_err;
+    }
+
+    esp_restart(); // this function never returns
+
+    return ESP_OK;
+}
+
+void trigger_ota_update(char* version) {
+    const esp_app_desc_t* current = esp_ota_get_app_description();
+    ESP_LOGD(OTA_LOGGER, "Currently running %s version %s", current->project_name, current->version);
+
+    if (strcmp(version, current->version) == 0) {
+        // already to latest version
+        return;
+    }
+
+    nvs_handle_t nvs;
+    esp_err_t err = nvs_open("ota", NVS_READONLY, &nvs);
+    if (err != ESP_OK) {
+        ESP_LOGE(OTA_LOGGER, "Error (%s) opening NVS handle!\n", esp_err_to_name(err));
+        return;
+    }
+    char* update_url_pattern = get_nvs_string(nvs, "update_url");
+    nvs_close(nvs);
+    if (update_url_pattern == NULL) {
+        return;
+    }
+
+    const size_t buffer_size = 256;
+    char update_url[buffer_size];
+
+    // Format the update URL
+    if (!snprintf(update_url, buffer_size, update_url_pattern, version)) {
+        ESP_LOGD(OTA_LOGGER, "trigger_ota_update: snprintf failed!");
+        free(update_url_pattern);
+        return;
+    }
+
+    esp_err_t ret = do_firmware_upgrade(update_url);
+    ESP_LOGW(OTA_LOGGER, "do_firmware_upgrade failed with error %d", ret);
+}

main/ota.h

@@ -0,0 +1,6 @@
+#ifndef __OTA_H__
+#define __OTA_H__
+
+void trigger_ota_update(char* version);
+
+#endif

provision/.gitignore

@@ -1,2 +1,5 @@
 # contains sensitive data
 sdkconfig
+config.dev
+config.prod
+sdkconfig.defaults

provision/main/Kconfig.projbuild

@@ -36,4 +36,10 @@ menu "Provisioning data"
         help
             MQTT password.
 
+    config FIRMWARE_URL_PATTERN
+        string "Firmware URL pattern"
+        default ""
+        help
+            Where to download a specific version of the firmware. Complete URL. Must include "%s".
+
 endmenu

provision/main/provision.c

@@ -135,6 +135,10 @@ void wifi_init_sta(void)
     nvs_set_str(nvs, "password", CONFIG_MQTT_PASSWORD);
     nvs_close(nvs);
 
+    ESP_ERROR_CHECK(nvs_open("ota", NVS_READWRITE, &nvs));
+    nvs_set_str(nvs, "update_url", CONFIG_FIRMWARE_URL_PATTERN);
+    nvs_close(nvs);
+
     nvs_dumpall();
 
     /* The event will not be processed after unregister */