esp-idf/examples/protocols/https_request/main/https_request_example_main.c

/* HTTPS GET Example using plain mbedTLS sockets
 *
 * Contacts the howsmyssl.com API via TLS v1.2 and reads a JSON
 * response.
 *
 * Adapted from the ssl_client1 example in mbedtls.
 *
 * Original Copyright (C) 2006-2016, ARM Limited, All Rights Reserved, Apache 2.0 License.
 * Additions Copyright (C) Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD, Apache 2.0 License.
 *
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#include <string.h>
#include <stdlib.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "esp_wifi.h"
#include "esp_event.h"
#include "esp_log.h"
#include "esp_system.h"
#include "nvs_flash.h"
#include "protocol_examples_common.h"
#include "esp_netif.h"

#include "lwip/err.h"
#include "lwip/sockets.h"
#include "lwip/sys.h"
#include "lwip/netdb.h"
#include "lwip/dns.h"

#include "esp_tls.h"
#include "esp_crt_bundle.h"

/* Constants that aren't configurable in menuconfig */
#define WEB_SERVER "www.howsmyssl.com"
#define WEB_PORT "443"
#define WEB_URL "https://www.howsmyssl.com/a/check"

static const char *TAG = "example";

static const char *REQUEST = "GET " WEB_URL " HTTP/1.1\r\n"
    "Host: "WEB_SERVER"\r\n"
    "User-Agent: esp-idf/1.0 esp32\r\n"
    "\r\n";

static void https_get_task(void *pvParameters)
{
    char buf[512];
    int ret, len;

    while(1) {
        esp_tls_cfg_t cfg = {
            .crt_bundle_attach = esp_crt_bundle_attach,
        };

        struct esp_tls *tls = esp_tls_conn_http_new(WEB_URL, &cfg);

        if(tls != NULL) {
            ESP_LOGI(TAG, "Connection established...");
        } else {
            ESP_LOGE(TAG, "Connection failed...");
            goto exit;
        }

        size_t written_bytes = 0;
        do {
            ret = esp_tls_conn_write(tls,
                                     REQUEST + written_bytes,
                                     strlen(REQUEST) - written_bytes);
            if (ret >= 0) {
                ESP_LOGI(TAG, "%d bytes written", ret);
                written_bytes += ret;
            } else if (ret != ESP_TLS_ERR_SSL_WANT_READ  && ret != ESP_TLS_ERR_SSL_WANT_WRITE) {
                ESP_LOGE(TAG, "esp_tls_conn_write  returned 0x%x", ret);
                goto exit;
            }
        } while(written_bytes < strlen(REQUEST));

        ESP_LOGI(TAG, "Reading HTTP response...");

        do
        {
            len = sizeof(buf) - 1;
            bzero(buf, sizeof(buf));
            ret = esp_tls_conn_read(tls, (char *)buf, len);

            if(ret == ESP_TLS_ERR_SSL_WANT_WRITE  || ret == ESP_TLS_ERR_SSL_WANT_READ)
                continue;

            if(ret < 0)
           {
                ESP_LOGE(TAG, "esp_tls_conn_read  returned -0x%x", -ret);
                break;
            }

            if(ret == 0)
            {
                ESP_LOGI(TAG, "connection closed");
                break;
            }

            len = ret;
            ESP_LOGD(TAG, "%d bytes read", len);
            /* Print response directly to stdout as it is read */
            for(int i = 0; i < len; i++) {
                putchar(buf[i]);
            }
        } while(1);

    exit:
        esp_tls_conn_delete(tls);
        putchar('\n'); // JSON output doesn't have a newline at end

        static int request_count;
        ESP_LOGI(TAG, "Completed %d requests", ++request_count);

        for(int countdown = 10; countdown >= 0; countdown--) {
            ESP_LOGI(TAG, "%d...", countdown);
            vTaskDelay(1000 / portTICK_PERIOD_MS);
        }
        ESP_LOGI(TAG, "Starting again!");
    }
}

void app_main(void)
{
    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());

    xTaskCreate(&https_get_task, "https_get_task", 8192, NULL, 5, NULL);
}