ESP32向带POST路由网站发送HTTPS POST请求遇阻，求排查

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2026-7-29

排查ESP32通过HTTPS POST发送传感器数据的问题

我正在开发一个项目，需要将传感器读数发送至网站进行绘图展示。最初使用原生HTTPClient模块搭配WiFiClient发送POST请求但无法正常工作，经查询得知需使用支持HTTPS的WiFiClientSecure库。修改代码后仍无法正常运行，以下是相关代码及排查建议：

初始HTTPClient代码（无法处理HTTPS）

#include <WiFi.h>
#include <HTTPClient.h>

const char* ssid = "dssdf";  // Enter SSID here
const char* password = "skdjfh";//.. password

//const char* serverName = "monitor.com";
//Domain name with URL path or IP address with path
const char* serverName = "https://...../post_data";

unsigned long lastTime = 0;
unsigned long timerDelay = 2000;

void setup() {
  Serial.begin(115200);

  WiFi.begin(ssid, password);
  Serial.println("Connecting");
  while(WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to WiFi network with IP Address: ");
  Serial.println(WiFi.localIP());
 
  Serial.println("Timer set to 5 seconds (timerDelay variable), it will take 5 seconds before publishing the first reading.");
}

void loop() {
  
  if ((millis() - lastTime) > timerDelay) {
    //Check WiFi connection status
    if(WiFi.status()== WL_CONNECTED){
      WiFiClient client;
      HTTPClient http;
    
      // Domain name with URL path or IP address with path
      http.begin(client, serverName);
      
      // Specify content-type header
      http.addHeader("Content-Type", "text/plain");
      // Data to send with HTTP POST
      String httpRequestData = "103";           
     
      int httpResponseCode = http.POST(httpRequestData);
      
      Serial.print("HTTP Response code: ");
      Serial.println(httpResponseCode);
        
      // Free resources
      http.end();
    }
    else {
      Serial.println("WiFi Disconnected");
    }
    lastTime = millis();
  }
}

修改后的WiFiClientSecure代码片段

const char* path = "/post_data";

// the SHA-1 fingerprint of the website's SSL certificate
const char fingerprint[] PROGMEM = "b2....................B";

void setup() {
 ............;
  Serial.println("Connected to Wi-Fi");
}

void loop() {
  // Wait for the Wi-Fi connection to be established
  if (WiFi.status() == WL_CONNECTED) {
    // Use WiFiClientSecure class to create TLS connection
    WiFiClientSecure client;

    if (client.verify(fingerprint, host)) 
   {  
    // Connect to the server
    if (client.connect(host, 3000)) {
      Serial.println("Connected to server");

      // Construct the POST request
      String data = "123";
      String request = "POST " + String(path) + " HTTP/1.1\n" +
                       "Host: " + String(host) + "\n" +
                       "Content-Type: application/x-www-form-urlencoded\n" +
                       "Content-Length: " + String(data.length()) + "\n" +
                       "\n" +data;

      // Send the POST request
      client.print(request);

      // Wait for the server to respond
      while (client.connected()) {
        String line = client.readStringUntil('\n');
        if (line == "\r") {
          Serial.println("Response headers received");
          break;
        }
      }

      // Read and print the response body
      while (client.available()) {
        String line = client.readStringUntil('\n');
        Serial.println(line);
      }

      // Close the connection
      client.stop();
      Serial.println("Connection closed");
    } else {
      Serial.println("Connection failed");
    }
  }
  else 
  {
  Serial.println("certificate doesn't match");
 }
 }
  else {
    Serial.println("Wi-Fi not connected");
  }
    delay(10000);
}

核心排查点与修复建议

1. 端口号错误

HTTPS协议默认端口是443，你代码中使用的3000是非标准端口，除非服务器明确配置了该端口作为HTTPS入口，否则必须改为443。

2. 证书指纹问题

确保指纹是目标网站SSL证书的SHA-1格式（共40个字符），注意大小写和字符完整性，指纹不匹配会直接触发certificate doesn't match提示。
临时测试可添加client.setInsecure();跳过指纹验证（正式环境禁止使用，存在安全风险），确认是否是证书验证导致的连接失败。

3. HTTP请求格式错误

HTTP协议要求用\r\n作为换行符，你代码中用的\n会导致服务器无法正确解析请求头，需将所有换行替换为\r\n。同时建议添加Connection: close头，避免连接长时间占用资源。

4. 变量未定义问题

代码片段中host变量未定义，需补充：

const char* host = "你的服务器域名"; // 例如 monitor.com

5. 串口调试定位

根据串口输出信息精准定位：

若输出certificate doesn't match：重新获取证书指纹，或检查证书是否过期/更换。
若输出Connection failed：检查端口、域名解析、服务器可用性，或用client.connectError()打印具体错误码。
若连接成功但无预期响应：用Postman/curl测试服务器接口是否正常，确认请求格式与服务器要求匹配。

修正后的完整参考代码

#include <WiFi.h>
#include <WiFiClientSecure.h>

const char* ssid = "dssdf";
const char* password = "skdjfh";
const char* host = "monitor.com";
const char* path = "/post_data";
const char fingerprint[] PROGMEM = "b2xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxB";

unsigned long lastTime = 0;
const unsigned long timerDelay = 10000;

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  Serial.println("Connecting to WiFi...");
  while(WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nConnected to WiFi, IP: " + WiFi.localIP().toString());
}

void loop() {
  if ((millis() - lastTime) > timerDelay) {
    if(WiFi.status() == WL_CONNECTED) {
      WiFiClientSecure client;

      // 临时测试用，正式环境删除
      // client.setInsecure();

      if (client.verify(fingerprint, host)) {
        Serial.println("Certificate verified");
        if (client.connect(host, 443)) {
          Serial.println("Connected to server");
          String data = "123"; // 替换为传感器读数
          String request = "POST " + String(path) + " HTTP/1.1\r\n" +
                           "Host: " + String(host) + "\r\n" +
                           "Content-Type: application/x-www-form-urlencoded\r\n" +
                           "Content-Length: " + String(data.length()) + "\r\n" +
                           "Connection: close\r\n" +
                           "\r\n" + data;

          client.print(request);

          // 读取响应头
          while (client.connected()) {
            String line = client.readStringUntil('\n');
            if (line == "\r") {
              Serial.println("\nResponse headers:");
              break;
            }
            Serial.println(line);
          }

          // 读取响应体
          Serial.println("Response body:");
          while (client.available()) {
            String line = client.readStringUntil('\n');
            Serial.println(line);
          }

          client.stop();
          Serial.println("Connection closed");
        } else {
          Serial.println("Failed to connect to server");
          Serial.print("Error code: ");
          Serial.println(client.connectError());
        }
      } else {
        Serial.println("Certificate verification failed");
      }
    } else {
      Serial.println("WiFi disconnected, reconnecting...");
      WiFi.reconnect();
    }
    lastTime = millis();
  }
}

内容的提问来源于stack exchange，提问作者kisuke_urahara