esp-idf 支持许多posix接口， 其中就包含 time 相关的，我可以通过相关接口获取和修改系统时间

#include "esp_err.h"
#include "esp_event.h"
#include "esp_log.h"
#include "esp_netif.h"
#include "esp_netif_sntp.h"
#include "esp_sntp.h"
#include "esp_wifi.h"
#include "esp_wifi_default.h"
#include "esp_wifi_types_generic.h"
#include "freertos/FreeRTOS.h"
#include "freertos/idf_additions.h"
#include "freertos/task.h"
#include "nvs_flash.h"
#include "time.h"
#include <assert.h>
#include <lwip/netdb.h>
#include <stdio.h>

static const char *TAG = "HTTPS";
bool isConnected = false;
static EventGroupHandle_t s_wifi_event_group;
#define WIFI_CONNECTED_BIT BIT0
#define WIFI_FAIL_BIT BIT1
static int s_retry_num = 0;

static void event_handler(void *arg, esp_event_base_t event_base,
                          int32_t event_id, void *event_data) {
  if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {
    esp_wifi_connect();
  } else if (event_base == WIFI_EVENT &&
             event_id == WIFI_EVENT_STA_DISCONNECTED) {
    if (s_retry_num < 5) {
      esp_wifi_connect();
      s_retry_num += 1;
      ESP_LOGI("STA", "retry connect to the AP");
    } else {
      // 超时
      xEventGroupSetBits(s_wifi_event_group, WIFI_FAIL_BIT);
    }
  } else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_CONNECTED) {
    wifi_event_sta_connected_t *event =
        (wifi_event_sta_connected_t *)event_data;
    ESP_LOGI("STA", "connected: %s", event->ssid);
  } else if (event_base == IP_EVENT && event_id == IP_EVENT_STA_GOT_IP) {
    ip_event_got_ip_t *event = (ip_event_got_ip_t *)event_data;
    ESP_LOGI(TAG, "got ip:" IPSTR, IP2STR(&event->ip_info.ip));
    s_retry_num = 0;
    // 拿到 IP, 应该可以冲浪了
    xEventGroupSetBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
  }
}

void wifiInit() {

  // 初始化 netif 和事件轮训
  ESP_ERROR_CHECK(esp_netif_init());
  ESP_ERROR_CHECK(esp_event_loop_create_default());

  // 默认配置设置wifi
  wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
  ESP_ERROR_CHECK(esp_wifi_init(&cfg));

  // 注册事件回调
  ESP_ERROR_CHECK(esp_event_handler_instance_register(
      WIFI_EVENT, ESP_EVENT_ANY_ID, &event_handler, NULL, NULL));
  ESP_ERROR_CHECK(esp_event_handler_instance_register(
      IP_EVENT, IP_EVENT_STA_GOT_IP, &event_handler, NULL, NULL));

  // 初始化 sta 和 netif, 个人感觉是为netif接入sta
  esp_netif_t *sta_netif = esp_netif_create_default_wifi_sta();
  assert(sta_netif);
  ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));

  // sta 配置， 你要连接哪个wifi
  wifi_config_t wifi_config = {
      .sta =
          {
              .ssid = "Man_2.4GHz",
              .password = "liang114514",
          },
  };
  ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_STA, &wifi_config));

  // 开始干活
  ESP_ERROR_CHECK(esp_wifi_start());
}

static void time_sync_notification_cb(struct timeval *tv) {
  ESP_LOGI(TAG, "Notification of a time synchronization event");
}

static void initialize_sntp(void) {
  ESP_LOGI("SNTP", "Initializing SNTP");
  esp_sntp_config_t config = ESP_NETIF_SNTP_DEFAULT_CONFIG("pool.ntp.org");
  sntp_set_time_sync_notification_cb(time_sync_notification_cb);
  esp_netif_sntp_init(&config);
}

static void obtain_time(void) {
  initialize_sntp();

  // 等待时间同步
  time_t now = 0;
  struct tm timeinfo = {0};
  int retry = 0;
  const int retry_count = 10;
  while (sntp_get_sync_status() == SNTP_SYNC_STATUS_RESET &&
         ++retry < retry_count) {
    ESP_LOGI(TAG, "Waiting for system time to be set... (%d/%d)", retry,
             retry_count);
    vTaskDelay(2000 / portTICK_PERIOD_MS);
  }
  time(&now);
  localtime_r(&now, &timeinfo);
}

void app_main() {
  esp_err_t ret = nvs_flash_init();
  if (ret == ESP_ERR_NVS_NO_FREE_PAGES ||
      ret == ESP_ERR_NVS_NEW_VERSION_FOUND) {
    ESP_ERROR_CHECK(nvs_flash_erase());
    ret = nvs_flash_init();
  }
  ESP_ERROR_CHECK(ret);

  s_wifi_event_group = xEventGroupCreate();
  wifiInit();
  // 无限等待, 返回
  EventBits_t bits = xEventGroupWaitBits(s_wifi_event_group,
                                         WIFI_CONNECTED_BIT | WIFI_FAIL_BIT,
                                         pdFALSE, pdFALSE, portMAX_DELAY);

  time_t now;
  struct tm timeinfo;
  time(&now);
  localtime_r(&now, &timeinfo);
  if (timeinfo.tm_year < (2016 - 1900)) {
    ESP_LOGI(
        TAG,
        "Time is not set yet. Connecting to WiFi and getting time over NTP.");
    obtain_time();
  }

  // 设置时区（以中国标准时间为例）
  setenv("TZ", "CST-8", 1);
  tzset();

  // 循环输出时间
  char strftime_buf[64];
  while (1) {
    time(&now);
    localtime_r(&now, &timeinfo);
    strftime(strftime_buf, sizeof(strftime_buf), "%Y-%m-%d %H:%M:%S",
             &timeinfo);
    ESP_LOGI(TAG, "Current date/time in Shanghai: %s", strftime_buf);
    vTaskDelay(1000 / portTICK_PERIOD_MS);
  }
}