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/* 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.
*
* SPDX-FileCopyrightText: The Mbed TLS Contributors
*
* SPDX-License-Identifier: Apache-2.0
*
* SPDX-FileContributor: 2015-2024 Espressif Systems (Shanghai) CO LTD
*/
#include <string.h>
#include <stdlib.h>
#include <inttypes.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.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 "mbedtls/platform.h"
#include "mbedtls/net_sockets.h"
#include "mbedtls/esp_debug.h"
#include "mbedtls/ssl.h"
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "mbedtls/error.h"
#ifdef CONFIG_MBEDTLS_SSL_PROTO_TLS1_3
#include "psa/crypto.h"
#endif
#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/1.0\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, flags, len;
mbedtls_entropy_context entropy;
mbedtls_ctr_drbg_context ctr_drbg;
mbedtls_ssl_context ssl;
mbedtls_x509_crt cacert;
mbedtls_ssl_config conf;
mbedtls_net_context server_fd;
#ifdef CONFIG_MBEDTLS_SSL_PROTO_TLS1_3
psa_status_t status = psa_crypto_init();
if (status != PSA_SUCCESS) {
ESP_LOGE(TAG, "Failed to initialize PSA crypto, returned %d", (int) status);
return;
}
#endif
mbedtls_ssl_init(&ssl);
mbedtls_x509_crt_init(&cacert);
mbedtls_ctr_drbg_init(&ctr_drbg);
ESP_LOGI(TAG, "Seeding the random number generator");
mbedtls_ssl_config_init(&conf);
mbedtls_entropy_init(&entropy);
if((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy,
NULL, 0)) != 0)
{
ESP_LOGE(TAG, "mbedtls_ctr_drbg_seed returned %d", ret);
abort();
}
ESP_LOGI(TAG, "Attaching the certificate bundle...");
ret = esp_crt_bundle_attach(&conf);
if(ret < 0)
{
ESP_LOGE(TAG, "esp_crt_bundle_attach returned -0x%x", -ret);
abort();
}
ESP_LOGI(TAG, "Setting hostname for TLS session...");
/* Hostname set here should match CN in server certificate */
if((ret = mbedtls_ssl_set_hostname(&ssl, WEB_SERVER)) != 0)
{
ESP_LOGE(TAG, "mbedtls_ssl_set_hostname returned -0x%x", -ret);
abort();
}
ESP_LOGI(TAG, "Setting up the SSL/TLS structure...");
if((ret = mbedtls_ssl_config_defaults(&conf,
MBEDTLS_SSL_IS_CLIENT,
MBEDTLS_SSL_TRANSPORT_STREAM,
MBEDTLS_SSL_PRESET_DEFAULT)) != 0)
{
ESP_LOGE(TAG, "mbedtls_ssl_config_defaults returned %d", ret);
goto exit;
}
mbedtls_ssl_conf_authmode(&conf, MBEDTLS_SSL_VERIFY_REQUIRED);
mbedtls_ssl_conf_ca_chain(&conf, &cacert, NULL);
mbedtls_ssl_conf_rng(&conf, mbedtls_ctr_drbg_random, &ctr_drbg);
#ifdef CONFIG_MBEDTLS_DEBUG
mbedtls_esp_enable_debug_log(&conf, CONFIG_MBEDTLS_DEBUG_LEVEL);
#endif
if ((ret = mbedtls_ssl_setup(&ssl, &conf)) != 0)
{
ESP_LOGE(TAG, "mbedtls_ssl_setup returned -0x%x", -ret);
goto exit;
}
while(1) {
mbedtls_net_init(&server_fd);
ESP_LOGI(TAG, "Connecting to %s:%s...", WEB_SERVER, WEB_PORT);
if ((ret = mbedtls_net_connect(&server_fd, WEB_SERVER,
WEB_PORT, MBEDTLS_NET_PROTO_TCP)) != 0)
{
ESP_LOGE(TAG, "mbedtls_net_connect returned -%x", -ret);
goto exit;
}
ESP_LOGI(TAG, "Connected.");
mbedtls_ssl_set_bio(&ssl, &server_fd, mbedtls_net_send, mbedtls_net_recv, NULL);
ESP_LOGI(TAG, "Performing the SSL/TLS handshake...");
while ((ret = mbedtls_ssl_handshake(&ssl)) != 0)
{
if (ret != MBEDTLS_ERR_SSL_WANT_READ && ret != MBEDTLS_ERR_SSL_WANT_WRITE)
{
ESP_LOGE(TAG, "mbedtls_ssl_handshake returned -0x%x", -ret);
goto exit;
}
}
ESP_LOGI(TAG, "Verifying peer X.509 certificate...");
if ((flags = mbedtls_ssl_get_verify_result(&ssl)) != 0)
{
/* In real life, we probably want to close connection if ret != 0 */
ESP_LOGW(TAG, "Failed to verify peer certificate!");
bzero(buf, sizeof(buf));
mbedtls_x509_crt_verify_info(buf, sizeof(buf), " ! ", flags);
ESP_LOGW(TAG, "verification info: %s", buf);
}
else {
ESP_LOGI(TAG, "Certificate verified.");
}
ESP_LOGI(TAG, "Cipher suite is %s", mbedtls_ssl_get_ciphersuite(&ssl));
ESP_LOGI(TAG, "Writing HTTP request...");
size_t written_bytes = 0;
do {
ret = mbedtls_ssl_write(&ssl,
(const unsigned char *)REQUEST + written_bytes,
strlen(REQUEST) - written_bytes);
if (ret >= 0) {
ESP_LOGI(TAG, "%d bytes written", ret);
written_bytes += ret;
} else if (ret != MBEDTLS_ERR_SSL_WANT_WRITE && ret != MBEDTLS_ERR_SSL_WANT_READ) {
ESP_LOGE(TAG, "mbedtls_ssl_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 = mbedtls_ssl_read(&ssl, (unsigned char *)buf, len);
#if CONFIG_MBEDTLS_SSL_PROTO_TLS1_3 && CONFIG_MBEDTLS_CLIENT_SSL_SESSION_TICKETS
if (ret == MBEDTLS_ERR_SSL_RECEIVED_NEW_SESSION_TICKET) {
ESP_LOGD(TAG, "got session ticket in TLS 1.3 connection, retry read");
continue;
}
#endif // CONFIG_MBEDTLS_SSL_PROTO_TLS1_3 && CONFIG_MBEDTLS_CLIENT_SSL_SESSION_TICKETS
if (ret == MBEDTLS_ERR_SSL_WANT_READ || ret == MBEDTLS_ERR_SSL_WANT_WRITE) {
continue;
}
if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY) {
ret = 0;
break;
}
if (ret < 0) {
ESP_LOGE(TAG, "mbedtls_ssl_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);
mbedtls_ssl_close_notify(&ssl);
exit:
mbedtls_ssl_session_reset(&ssl);
mbedtls_net_free(&server_fd);
if (ret != 0) {
mbedtls_strerror(ret, buf, 100);
ESP_LOGE(TAG, "Last error was: -0x%x - %s", -ret, buf);
}
putchar('\n'); // JSON output doesn't have a newline at end
static int request_count;
ESP_LOGI(TAG, "Completed %d requests", ++request_count);
printf("Minimum free heap size: %" PRIu32 " bytes\n", esp_get_minimum_free_heap_size());
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);
}
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