esp_https_ota: Add a feature to set custom headers to esp_https_ota request

Closes: https://github.com/espressif/esp-idf/issues/3097

components/esp_https_ota/include/esp_https_ota.h

@@ -22,12 +22,14 @@ extern "C" {
 #endif
 
 typedef void *esp_https_ota_handle_t;
+typedef esp_err_t(*http_client_init_cb_t)(esp_http_client_handle_t);
 
 /**
  * @brief ESP HTTPS OTA configuration
  */
 typedef struct {
     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 */
 } esp_https_ota_config_t;
 
 #define ESP_ERR_HTTPS_OTA_BASE            (0x9000)

components/esp_https_ota/src/esp_https_ota.c

@@ -173,6 +173,14 @@ esp_err_t esp_https_ota_begin(esp_https_ota_config_t *ota_config, esp_https_ota_
         goto failure;
     }
 
+    if (ota_config->http_client_init_cb) {
+        err = ota_config->http_client_init_cb(https_ota_handle->http_client);
+        if (err != ESP_OK) {
+            ESP_LOGE(TAG, "http_client_init_cb returned %d", err);
+            goto failure;
+        }
+    }
+
     err = _http_connect(https_ota_handle->http_client);
     if (err != ESP_OK) {
         ESP_LOGE(TAG, "Failed to establish HTTP connection");