ESP HTTPS OTA 升级

概述

esp_https_ota 是现有 OTA（空中升级）API 的抽象层，其中提供了简化的 API，能够通过 HTTPS 升级固件。

应用示例

esp_err_t do_firmware_upgrade()
{
    esp_http_client_config_t config = {
        .url = CONFIG_FIRMWARE_UPGRADE_URL,
        .cert_pem = (char *)server_cert_pem_start,
    };
    esp_https_ota_config_t ota_config = {
        .http_config = &config,
    };
    esp_err_t ret = esp_https_ota(&ota_config);
    if (ret == ESP_OK) {
        esp_restart();
    } else {
        return ESP_FAIL;
    }
    return ESP_OK;
}

服务器验证

验证服务器时，应将 PEM 格式的根证书提供给 esp_http_client_config_t::cert_pem 成员。如需了解有关服务器验证的更多信息，请参阅 TLS 服务器验证。

备注

应使用服务器端点的根证书应用于验证，而不能使用证书链中的任何中间证书，因为根证书有效期最长，且通常长时间维持不变。用户还可以通过 esp_http_client_config_t::crt_bundle_attach 成员使用 ESP x509 证书包 功能进行验证，其中涵盖了大多数受信任的根证书。

通过 HTTPS 下载部分镜像

要使用部分镜像下载功能，请启用 esp_https_ota_config_t 中的 partial_http_download 配置。启用此配置后，固件镜像将通过多个指定大小的 HTTP 请求进行下载。将 max_http_request_size 设置为所需值，即可指定每个请求的最大内容长度。

在从 AWS S3 等服务获取镜像时，这一选项非常有用。在启用该选项时，可以将 mbedTLS Rx 的 buffer 大小（即 CONFIG_MBEDTLS_SSL_IN_CONTENT_LEN）设置为较小的值。不启用此配置时，无法将其设置为较小值。

mbedTLS Rx buffer 的默认大小为 16 KB，但如果将 partial_http_download 的 max_http_request_size 设置为 4 KB，便能将 mbedTLS Rx 的 buffer 减小到 4 KB。使用这一配置方式预计可以节省约 12 KB 内存。

签名验证

要进一步提升安全性，还可以验证 OTA 固件镜像的签名。更多内容请参考没有安全启动的安全 OTA 升级。

高级 API

esp_https_ota 还提供一些高级 API，用于查看 OTA 过程的更多信息并满足其他控制需求。

如需查看使用高级 ESP_HTTPS_OTA API 的示例，请前往 system/ota/advanced_https_ota。

使用预加密固件进行 OTA 升级

如需使用预加密的固件进行 OTA 升级，请在组件的菜单配置中启用 CONFIG_ESP_HTTPS_OTA_DECRYPT_CB 选项。

如需查看使用预加密固件进行 OTA 升级的示例，请前往 system/ota/pre_encrypted_ota。

OTA 系统事件

ESP HTTPS OTA 过程中可能发生各种系统事件。当特定事件发生时，会由事件循环库触发处理程序。此处理程序必须使用 esp_event_handler_register() 注册。这有助于 ESP HTTPS OTA 进行事件处理。

esp_https_ota_event_t 中包含了使用 ESP HTTPS OTA 升级时可能发生的所有事件。

事件处理程序示例

/* 用于捕获系统事件的事件处理程序 */
static void event_handler(void* arg, esp_event_base_t event_base,
                        int32_t event_id, void* event_data)
{
    if (event_base == ESP_HTTPS_OTA_EVENT) {
        switch (event_id) {
            case ESP_HTTPS_OTA_START:
                ESP_LOGI(TAG, "OTA started");
                break;
            case ESP_HTTPS_OTA_CONNECTED:
                ESP_LOGI(TAG, "Connected to server");
                break;
            case ESP_HTTPS_OTA_GET_IMG_DESC:
                ESP_LOGI(TAG, "Reading Image Description");
                break;
            case ESP_HTTPS_OTA_VERIFY_CHIP_ID:
                ESP_LOGI(TAG, "Verifying chip id of new image: %d", *(esp_chip_id_t *)event_data);
                break;
            case ESP_HTTPS_OTA_DECRYPT_CB:
                ESP_LOGI(TAG, "Callback to decrypt function");
                break;
            case ESP_HTTPS_OTA_WRITE_FLASH:
                ESP_LOGD(TAG, "Writing to flash: %d written", *(int *)event_data);
                break;
            case ESP_HTTPS_OTA_UPDATE_BOOT_PARTITION:
                ESP_LOGI(TAG, "Boot partition updated. Next Partition: %d", *(esp_partition_subtype_t *)event_data);
                break;
            case ESP_HTTPS_OTA_FINISH:
                ESP_LOGI(TAG, "OTA finish");
                break;
            case ESP_HTTPS_OTA_ABORT:
                ESP_LOGI(TAG, "OTA abort");
                break;
        }
    }
}

系统事件循环中，不同 ESP HTTPS OTA 事件的预期数据类型如下所示：

ESP_HTTPS_OTA_START : NULL

ESP_HTTPS_OTA_CONNECTED : NULL

ESP_HTTPS_OTA_GET_IMG_DESC : NULL

ESP_HTTPS_OTA_VERIFY_CHIP_ID : esp_chip_id_t

ESP_HTTPS_OTA_DECRYPT_CB : NULL

ESP_HTTPS_OTA_WRITE_FLASH : int

ESP_HTTPS_OTA_UPDATE_BOOT_PARTITION : esp_partition_subtype_t

ESP_HTTPS_OTA_FINISH : NULL

ESP_HTTPS_OTA_ABORT : NULL

API 参考

Header File

components/esp_https_ota/include/esp_https_ota.h
This header file can be included with:
#include "esp_https_ota.h"
This header file is a part of the API provided by the esp_https_ota component. To declare that your component depends on esp_https_ota, add the following to your CMakeLists.txt:
REQUIRES esp_https_ota
or
PRIV_REQUIRES esp_https_ota

Functions

esp_err_t esp_https_ota(const esp_https_ota_config_t *ota_config)

HTTPS OTA Firmware upgrade.

This function allocates HTTPS OTA Firmware upgrade context, establishes HTTPS connection, reads image data from HTTP stream and writes it to OTA partition and finishes HTTPS OTA Firmware upgrade operation. This API supports URL redirection, but if CA cert of URLs differ then it should be appended to cert_pem member of ota_config->http_config.

备注

This API handles the entire OTA operation, so if this API is being used then no other APIs from esp_https_ota component should be called. If more information and control is needed during the HTTPS OTA process, then one can use esp_https_ota_begin and subsequent APIs. If this API returns successfully, esp_restart() must be called to boot from the new firmware image.

参数

ota_config -- [in] pointer to esp_https_ota_config_t structure.

返回

ESP_OK: OTA data updated, next reboot will use specified partition.
ESP_FAIL: For generic failure.
ESP_ERR_INVALID_ARG: Invalid argument
ESP_ERR_OTA_VALIDATE_FAILED: Invalid app image
ESP_ERR_NO_MEM: Cannot allocate memory for OTA operation.
ESP_ERR_FLASH_OP_TIMEOUT or ESP_ERR_FLASH_OP_FAIL: Flash write failed.
For other return codes, refer OTA documentation in esp-idf's app_update component.

esp_err_t esp_https_ota_begin(const esp_https_ota_config_t *ota_config, esp_https_ota_handle_t *handle)

Start HTTPS OTA Firmware upgrade.

This function initializes ESP HTTPS OTA context and establishes HTTPS connection. This function must be invoked first. If this function returns successfully, then esp_https_ota_perform should be called to continue with the OTA process and there should be a call to esp_https_ota_finish on completion of OTA operation or on failure in subsequent operations. This API supports URL redirection, but if CA cert of URLs differ then it should be appended to cert_pem member of http_config, which is a part of ota_config. In case of error, this API explicitly sets handle to NULL.

备注

This API is blocking, so setting is_async member of http_config structure will result in an error.

参数

ota_config -- [in] pointer to esp_https_ota_config_t structure
handle -- [out] pointer to an allocated data of type esp_https_ota_handle_t which will be initialised in this function

返回

ESP_OK: HTTPS OTA Firmware upgrade context initialised and HTTPS connection established
ESP_FAIL: For generic failure.
ESP_ERR_INVALID_ARG: Invalid argument (missing/incorrect config, certificate, etc.)
For other return codes, refer documentation in app_update component and esp_http_client component in esp-idf.

esp_err_t esp_https_ota_perform(esp_https_ota_handle_t https_ota_handle)

Read image data from HTTP stream and write it to OTA partition.

This function reads image data from HTTP stream and writes it to OTA partition. This function must be called only if esp_https_ota_begin() returns successfully. This function must be called in a loop since it returns after every HTTP read operation thus giving you the flexibility to stop OTA operation midway.

参数

https_ota_handle -- [in] pointer to esp_https_ota_handle_t structure

返回

ESP_ERR_HTTPS_OTA_IN_PROGRESS: OTA update is in progress, call this API again to continue.
ESP_OK: OTA update was successful
ESP_FAIL: OTA update failed
ESP_ERR_INVALID_ARG: Invalid argument
ESP_ERR_INVALID_VERSION: Invalid chip revision in image header
ESP_ERR_OTA_VALIDATE_FAILED: Invalid app image
ESP_ERR_NO_MEM: Cannot allocate memory for OTA operation.
ESP_ERR_FLASH_OP_TIMEOUT or ESP_ERR_FLASH_OP_FAIL: Flash write failed.
For other return codes, refer OTA documentation in esp-idf's app_update component.

bool esp_https_ota_is_complete_data_received(esp_https_ota_handle_t https_ota_handle)

Checks if complete data was received or not.

备注

This API can be called just before esp_https_ota_finish() to validate if the complete image was indeed received.

参数

https_ota_handle -- [in] pointer to esp_https_ota_handle_t structure

返回

false
true

esp_err_t esp_https_ota_finish(esp_https_ota_handle_t https_ota_handle)

Clean-up HTTPS OTA Firmware upgrade and close HTTPS connection.

This function closes the HTTP connection and frees the ESP HTTPS OTA context. This function switches the boot partition to the OTA partition containing the new firmware image.

备注

If this API returns successfully, esp_restart() must be called to boot from the new firmware image esp_https_ota_finish should not be called after calling esp_https_ota_abort

参数

https_ota_handle -- [in] pointer to esp_https_ota_handle_t structure

返回

ESP_OK: Clean-up successful
ESP_ERR_INVALID_STATE
ESP_ERR_INVALID_ARG: Invalid argument
ESP_ERR_OTA_VALIDATE_FAILED: Invalid app image

esp_err_t esp_https_ota_abort(esp_https_ota_handle_t https_ota_handle)

Clean-up HTTPS OTA Firmware upgrade and close HTTPS connection.

This function closes the HTTP connection and frees the ESP HTTPS OTA context.

备注

esp_https_ota_abort should not be called after calling esp_https_ota_finish

参数

https_ota_handle -- [in] pointer to esp_https_ota_handle_t structure

返回

ESP_OK: Clean-up successful
ESP_ERR_INVALID_STATE: Invalid ESP HTTPS OTA state
ESP_FAIL: OTA not started
ESP_ERR_NOT_FOUND: OTA handle not found
ESP_ERR_INVALID_ARG: Invalid argument

esp_err_t esp_https_ota_get_img_desc(esp_https_ota_handle_t https_ota_handle, esp_app_desc_t *new_app_info)

Reads app description from image header. The app description provides information like the "Firmware version" of the image.

备注

This API can be called only after esp_https_ota_begin() and before esp_https_ota_perform(). Calling this API is not mandatory.

参数

https_ota_handle -- [in] pointer to esp_https_ota_handle_t structure
new_app_info -- [out] pointer to an allocated esp_app_desc_t structure

返回

ESP_ERR_INVALID_ARG: Invalid arguments
ESP_ERR_INVALID_STATE: Invalid state to call this API. esp_https_ota_begin() not called yet.
ESP_FAIL: Failed to read image descriptor
ESP_OK: Successfully read image descriptor

int esp_https_ota_get_image_len_read(esp_https_ota_handle_t https_ota_handle)

This function returns OTA image data read so far.

备注

This API should be called only if esp_https_ota_perform() has been called atleast once or if esp_https_ota_get_img_desc has been called before.

参数

https_ota_handle -- [in] pointer to esp_https_ota_handle_t structure

返回

-1 On failure
total bytes read so far

int esp_https_ota_get_image_size(esp_https_ota_handle_t https_ota_handle)

This function returns OTA image total size.

备注

This API should be called after esp_https_ota_begin() has been already called. This can be used to create some sort of progress indication (in combination with esp_https_ota_get_image_len_read())

参数

https_ota_handle -- [in] pointer to esp_https_ota_handle_t structure

返回

-1 On failure or chunked encoding
total bytes of image

Structures

struct esp_https_ota_config_t

ESP HTTPS OTA configuration.

Public Members

const esp_http_client_config_t *http_config: ESP HTTP client configuration

http_client_init_cb_t http_client_init_cb: Callback after ESP HTTP client is initialised

bool bulk_flash_erase: Erase entire flash partition during initialization. By default flash partition is erased during write operation and in chunk of 4K sector size

bool partial_http_download: Enable Firmware image to be downloaded over multiple HTTP requests

int max_http_request_size: Maximum request size for partial HTTP download

Macros

ESP_ERR_HTTPS_OTA_BASE

ESP_ERR_HTTPS_OTA_IN_PROGRESS

Type Definitions

typedef void *esp_https_ota_handle_t

typedef esp_err_t (*http_client_init_cb_t)(esp_http_client_handle_t)

Enumerations

enum esp_https_ota_event_t

Events generated by OTA process.

Values:

enumerator ESP_HTTPS_OTA_START: OTA started

enumerator ESP_HTTPS_OTA_CONNECTED: Connected to server

enumerator ESP_HTTPS_OTA_GET_IMG_DESC: Read app description from image header

enumerator ESP_HTTPS_OTA_VERIFY_CHIP_ID: Verify chip id of new image

enumerator ESP_HTTPS_OTA_DECRYPT_CB: Callback to decrypt function

enumerator ESP_HTTPS_OTA_WRITE_FLASH: Flash write operation

enumerator ESP_HTTPS_OTA_UPDATE_BOOT_PARTITION: Boot partition update after successful ota update

enumerator ESP_HTTPS_OTA_FINISH: OTA finished

enumerator ESP_HTTPS_OTA_ABORT: OTA aborted

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