如何使用公网IP和SSL将ESP32连接到MQTT服务器？

#include <WiFi.h>
#include <PubSubClient.h>

const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";
const char* mqttServer = "your_MQTT_SERVER_IP";
const int mqttPort = 8883;
const char* mqttUser = "your_MQTT_USERNAME";
const char* mqttPassword = "your_MQTT_PASSWORD";

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
  WiFi.begin(ssid, password);
  
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  
  Serial.println("Connected to WiFi");
  
  client.setServer(mqttServer, mqttPort);
  client.setCallback(callback);
  
  while (!client.connected()) {
    if (client.connect("ESP32Client", mqttUser, mqttPassword )) {
      Serial.println("Connected to MQTT server");
    } else {
      Serial.print("Failed to connect to MQTT server, rc=");
      Serial.print(client.state());
      Serial.println(" retrying in 5 seconds");
      delay(5000);
    }
  }
  
  client.subscribe("your_topic");
}

void loop() {
  client.loop();
}

void callback(char* topic, byte* payload, unsigned int length) {
  // 处理接收到的消息
}

const char* rootCACertificate = \
"-----BEGIN CERTIFICATE-----\n" \
"YOUR_ROOT_CA_CERTIFICATE\n" \
"-----END CERTIFICATE-----\n";

client.setCACert(rootCACertificate);