[ESP32][esp-idf] https和mqtt同时签名冲突解决

现象：HTTPS建立连接的同时，MQTT也建立连接。双方都在签名证书，导致CPU抢占，致使看门狗超时。

解决：在tls层加互斥锁，防止同时建立连接。

修改文件：xEspressifcomponentsesp-tlsesp_tls_mbedtls.c

部分代码如下。

#include "freertos/FreeRTOS.h"

#include "freertos/semphr.h"

SemaphoreHandle_t _semaphore = NULL;

/**

 * @brief      Create TLS/SSL server session

 */

int esp_mbedtls_server_session_create(esp_tls_cfg_server_t *cfg, int sockfd, esp_tls_t *tls)

{

    if (tls == NULL || cfg == NULL) {

        return -1;

    }

    static bool fast = false;

    if (!fast) {

        fast = true;

        _semaphore = xSemaphoreCreateMutex();

    }

    tls->role = ESP_TLS_SERVER;

    tls->sockfd = sockfd;

    xSemaphoreTake(_semaphore, portMAX_DELAY);

    esp_err_t esp_ret = esp_create_mbedtls_handle(NULL, 0, cfg, tls);

    xSemaphoreGive(_semaphore);

    if (esp_ret != ESP_OK) {

        ESP_LOGE(TAG, "create_ssl_handle failed, returned [0x%04X] (%s)", esp_ret, esp_err_to_name(esp_ret));

        ESP_INT_EVENT_TRACKER_CAPTURE(tls->error_handle, ESP_TLS_ERR_TYPE_ESP, esp_ret);

        tls->conn_state = ESP_TLS_FAIL;

        return -1;

    }

    tls->read = esp_mbedtls_read;

    tls->write = esp_mbedtls_write;

    int ret;

    while ((ret = mbedtls_ssl_handshake(&tls->ssl)) != 0) {

        if (ret != ESP_TLS_ERR_SSL_WANT_READ && ret != ESP_TLS_ERR_SSL_WANT_WRITE) {

            ESP_LOGE(TAG, "mbedtls_ssl_handshake returned -0x%04X", -ret);

            mbedtls_print_error_msg(ret);

            tls->conn_state = ESP_TLS_FAIL;

            return ret;

        }

    }

    return 0;

}