Esp32 server - client: i think i must be missing something

Projects Programming
1

hi all

recently i have been putting together an esp32 serve / client project using examples from RNT

to POST data from a client to a server

the two relevant functions are:

for the server:

void loop(){
  WiFiClient client = server.available();   // Listen for incoming clients
  if (client)                    // If a new client connects,
  {
        Serial << "incoming data: ";
    String currentLine = "";                // make a String to hold incoming data from the client
    while (client.connected())
    {
      if (client.available())              // if the client has data
      {
        char c = client.read();             // read a byte, then
        header += c;
        Serial << c;
        if (c == '\n') {      // if the byte is a newline character
          // 2 blank lines means end of the request
          if (currentLine.length() == 0) {

          } else // if you got a newline, then clear currentLine
          { 
            Serial << endl << endl;
            // close the connection
            client.println("HTTP/1.1 200 OK");
            client.println("Content-type:text/html");
            client.println("Connection: close");
            client.println();
            //---------------------------------------
            // so here we can look for "/xxxx" in currentline and reply
        
            Serial << "loop received currentLine: " << currentLine <<
            "  header: " << header << endl;

            if(currentLine.indexOf("/nodeDetails") != -1)  // looking for hello
            {    // reply to the client
              client.println("node1 replying");
              Serial << "main loop replied: node1 replying" << endl << endl;
            }
            else  // looking for hello2
            {
              if(currentLine.indexOf("/hello2") != -1)
              {
                client.println("xxxx hello client2 xxxx");
              }
              else  // currentLine not got a reply
              {
              }
            }
            client.println();    // The HTTP response ends with another blank line
            currentLine = "";
            break;      // Break out of the while loop
          }
        } else if (c != '\r') {  // if you got anything else but a carriage return character,
          currentLine += c;      // add it to the end of the currentLine
        }
      }
    }
    header = "";      // clear header
    client.stop();    // Close the connection
  }
}

and for the post request:

void httpPostRequest(const char* serverName, const char* dataToSend)
{
  if(WiFi.status()== WL_CONNECTED){
    WiFiClient client;
    HTTPClient http;
    // Your Domain name with URL path or IP address with path
    http.begin(client, serverName);
      // for sendingtext
      http.addHeader("Content-Type", "text/plain");     // content type
      
      String httpRequestData = dataToSend;      // Data to send with HTTP POST
      // Send HTTP POST request
      //int httpResponseCode = http.POST(httpRequestData);
      int httpResponseCode = http.POST("**********");
      Serial << "httpPostRequest: " << endl <<
      "dataToSend: " << dataToSend << endl <<
      "serverName: " << serverName << endl <<
      "responsecode: " << httpResponseCode << endl << endl;
      
    http.end();   // free up resources
  }
}

my problem is:

in the server, the path, “serverName” i can see arrive

but sending the data: int httpResponseCode = http.POST("**********");

i never see the data arrive at the server

i think this must be due to me not understanding something,

can someone explain to me please where my problem is

thanks in advance

Dave

2

What's relevant is the complete code. Please post it.

3

I found the problem but since that part is not posted look around line

4

ok, thank you for coming back so quickly the whole code is several pages long but here’s the server sketch



/*********
  Rui Santos
  Complete project details at:
  https://randomnerdtutorials.com/esp32-web-server-arduino-ide/
*********/

// Load librarys
//#include <esp_wifi.h>
#include <WiFi.h>
#include <esp_wifi.h>
#include <ESPAsyncWebServer.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>
#include <TaskScheduler.h>
#include <Streaming.h>
#include <Preferences.h>


Preferences nvr;
//===============================================
// prototypes
void every1Sec();
void httpPostRequest(const char* serverName, const char* dataToSend);
//-------------------------------------
// included files
#include "nodeDetails.h"
#include "variables.h"
#include "utilities.h"
//-------------------------------------
// tasks
Task task1Sec   (1000,  TASK_FOREVER, &every1Sec);      // timing
Scheduler scheduler;
//-------------------------------------

WiFiServer server(node1Port);          // Set web server port
String header;                  // to save the HTTP request
//-------------------------------------
void every10Secs()
{

}
//-------------------------------------

void every1Sec() 
{
  timeSecs ++;
  if((timeSecs % 10) == 0)    // every 10 secs
  {
    every10Secs();
  }
  //---------------------------------
  if((timeSecs % 5) == 0)    // every 5 secs
  {
    if(sendGet) httpPostRequest("http://192.168.0.211:8080/nodeData", "hello from node1");
  }
  //---------------------------------
  if(timeSecs == 60)        // every minute
  {
    timeSecs = 0;
    myTime ++;
    if(myTime == 86400) myTime = 0; // 12 midnight
  }
}

//unsigned long currentTime = millis();   // Current time
//unsigned long previousTime = 0;         // Previous time
const long timeoutTime = 2000;          // set timeout to 2S
//---------------------------------
void connectWifi() {    // 192, 168, 0, 210
  //getChannel();
  uint8_t trys = 50;
  WiFi.mode(WIFI_AP_STA);  // Set device as a Wi-Fi Station
  if(!WiFi.config(node1Ip, gateway, subnet, primaryDNS, secondaryDNS)) {
    Serial.println("Failed to configure Static IP");
  }
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(".");
    trys --;
    if(trys == 0) {
      Serial << "trys = 0 restarting" << endl << endl;
      ESP.restart();
    }
  }
  Serial.print("Station IP Address: ");
  Serial.println(WiFi.localIP());
}

//---------------------------------
void setup() {
  Serial.begin(115200);
  delay(100);
  //---------------------------------
  // init tasks...... TaskScheduler
    scheduler.init();
    scheduler.addTask(task1Sec);
  //---------------------------
  newSettings = true;   // load new settings for node
  setMyDetails();       // set node details either nvr or new settings
  //---------------------------
  connectWifi();        // Connect to network
  //---------------------------------
  server.begin();
  task1Sec.enable();
}

void loop(){
  scheduler.execute();
  
  WiFiClient client = server.available();   // Listen for incoming clients
  if (client)                    // If a new client connects,
  {
        Serial << "incoming data: ";
    String currentLine = "";                // make a String to hold incoming data from the client
    while (client.connected())
    {
      if (client.available())              // if the client has data
      {
        char c = client.read();             // read a byte, then
        header += c;
        Serial << c;
        if (c == '\n') {      // if the byte is a newline character
          // 2 blank lines means end of the client HTTP request, 
          if (currentLine.length() == 0) {

          } else // if you got a newline, then clear currentLine
          { 
            Serial << endl << endl;
            // close the connection
            client.println("HTTP/1.1 200 OK");
            client.println("Content-type:text/html");
            client.println("Connection: close");
            client.println();
            //---------------------------------------
            // so here we can look for "/xxxx" in currentline and reply
        
            Serial << "loop received currentLine: " << currentLine <<
            "  header: " << header << endl;

            if(currentLine.indexOf("/nodeDetails") != -1)  // looking for hello
            {    // reply to the client
              client.println("node1 replying");
              Serial << "main loop replied: node1 replying" << endl << endl;
            }
            else  // looking for hello2
            {
              if(currentLine.indexOf("/hello2") != -1)
              {
                client.println("xxxx hello client2 xxxx");
              }
              else  // currentLine not got a reply
              {
              }
            }
            client.println();    // The HTTP response ends with another blank line
            currentLine = "";
            break;      // Break out of the while loop
          }
        } else if (c != '\r') {  // if you got anything else but a carriage return character,
          currentLine += c;      // add it to the end of the currentLine
        }
      }
    }
    header = "";      // clear header
    client.stop();    // Close the connection
  }
}
//---------------------------------
void httpPostRequest(const char* serverName, const char* dataToSend)
{
  if(WiFi.status()== WL_CONNECTED){
    WiFiClient client;
    HTTPClient http;
    // Your Domain name with URL path or IP address with path
    http.begin(client, serverName);
      // Specify content-type header
      // for sending Json in Json format
        //http.addHeader("Content-Type", "application/json");
        // Data to send with HTTP POST
        //int httpResponseCode = http.POST("{\"api_key\":\"tPmAT5Ab3j7F9\",\"sensor\":\"BME280\",\"value1\":\"24.25\",\"value2\":\"49.54\",\"value3\":\"1005.14\"}");

      // for sending text
      http.addHeader("Content-Type", "text/plain");     // content type
      //String httpRequestData = "hello from node1";    // Data to send with HTTP POST
      String httpRequestData = dataToSend;              // Data to send with HTTP POST

      // Send HTTP POST request
      int httpResponseCode = http.POST(httpRequestData);

      Serial << "httpPostRequest: " << endl <<
      "dataToSend: " << dataToSend << endl <<
      "serverName: " << serverName << endl <<
      "  responsecode: " << httpResponseCode << endl;
    
    http.end();   // free up resources
  }
}

and heres the client sketch

/*********
  Rui Santos
  Complete project details at:
  https://randomnerdtutorials.com/esp32-web-server-arduino-ide/
*********/

// Load librarys
#include <WiFi.h>
#include <esp_wifi.h>
#include <ESPAsyncWebServer.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>
#include <TaskScheduler.h>
#include <Streaming.h>
#include <Preferences.h>


Preferences nvr;
//---------------------------
/*  Using Dallas DS18B20 sensor
#include <OneWire.h>
#include <DallasTemperature.h>
OneWire oneWire(4); //DallasTempPin is 4;
DallasTemperature sensors(&oneWire);
// use sensors.begin(); in setup
*/
//===============================================
// prototypes
void every1Sec();
void httpPostRequest(const char* serverName, const char* dataToSend);
//-------------------------------------
// included files
#include "nodeDetails.h"
#include "variables.h"
#include "utilities.h"
//-------------------------------------
// tasks
Task task1Sec   (1000,  TASK_FOREVER, &every1Sec);      // timing
Scheduler scheduler;
//-------------------------------------

WiFiServer server(node2Port);          // Set web server port
String header;                          // to save the HTTP request
//-------------------------------------
void every10Secs()
{

}
//-------------------------------------

void every1Sec() 
{
  timeSecs ++;
  if((timeSecs % 10) == 0)    // every 10 secs
  {
    every10Secs();
  }
  //---------------------------------
  if((timeSecs % 7) == 0)    // every 5 secs
  {
    //if(sendGet) httpGETRequest("http://192.168.0.210:80/hellofromNode2");
    if(sendGet) httpPostRequest("http://192.168.0.210:80/nodeDetails", "hello from node2");

  }
  //---------------------------------
  if(timeSecs == 60)        // every minute
  {
    timeSecs = 0;
    myTime ++;
    if(myTime == 86400) myTime = 0; // 12 midnight
  }
}


const long timeoutTime = 2000;          // set timeout to 2S
//---------------------------
void connectWifi() {    // 192, 168, 0, 210
  //getChannel();
  uint8_t trys = 50;
  WiFi.mode(WIFI_AP_STA);  // Set device as a Wi-Fi Station
  if(!WiFi.config(node2Ip, gateway, subnet, primaryDNS, secondaryDNS)) {
    Serial.println("Failed to configure Static IP");
  }
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(".");
    trys --;
    if(trys == 0) {
      Serial << "trys = 0 restarting" << endl << endl;
      ESP.restart();
    }
  }
  Serial.print("Station IP Address: ");
  Serial.println(WiFi.localIP());
}

//---------------------------------
void setup() {
  Serial.begin(115200);
  delay(100);
  
  //---------------------------------
  // init tasks...... TaskScheduler
    scheduler.init();
    scheduler.addTask(task1Sec);
  //---------------------------
  newSettings = true;  // load new settings for node
  setMyDetails();  // set node details either fro, nvr or new settings
  //---------------------------------

  connectWifi();            // Connect to network
  //---------------------------------
  server.begin();
  task1Sec.enable();
}

void loop(){
  scheduler.execute();
  
  WiFiClient client = server.available();   // Listen for incoming clients
  if (client) {                             // If a new client connects,

    String currentLine = "";                // make a String to hold incoming data from the client
    while (client.connected())
    {
      if (client.available())              // if there's bytes to read from the client,
      {
        char c = client.read();             // read a byte, then
        header += c;
        if (c == '\n') {      // if the byte is a newline character
          // 2 blank lines means end of the client HTTP request, 
          if (currentLine.length() == 0) {

          } 
          else // if you got a newline, then clear currentLine
          { 
            Serial << "main loop received: " << currentLine << endl;
            // close the connection
            client.println("HTTP/1.1 200 OK");
            client.println("Content-type:text/html");
            client.println("Connection: close");
            client.println();
            Serial << "loop received currentLine: " << currentLine <<
            "  header: " << header << endl;

        
            if(currentLine.indexOf("/nodeData") != -1)  // looking for hello
            {    // reply to the client
              client.println("node1 replying");
              Serial << "main loop replied: node2 replying" << endl << endl;
            }
            else  // looking for hello2
            {
              if(currentLine.indexOf("/hello2") != -1)
              {
                client.println("xxxx hello client2 xxxx");
              }
              else
              {
              }
            }
           
        
            client.println();    // The HTTP response ends with another blank line
            currentLine = "";
            break;      // Break out of the while loop
          }
        } else if (c != '\r') {  // if you got anything else but a carriage return character,
          currentLine += c;      // add it to the end of the currentLine
        }
      }
    }
    header = "";    // clear header
    client.stop();    // Close the connection
  }
  //-------------------------------
}

//---------------------------------

void httpPostRequest(const char* serverName, const char* dataToSend)
{
  if(WiFi.status()== WL_CONNECTED){
    WiFiClient client;
    HTTPClient http;
    // Your Domain name with URL path or IP address with path
    http.begin(client, serverName);

      //http.addHeader("Content-Type", "text/plain");     // content type
      http.addHeader("Content-Type", "application/x-www-form-urlencoded");
      
      String httpRequestData = dataToSend;      // Data to send with HTTP POST
      // Send HTTP POST request
      //int httpResponseCode = http.POST(httpRequestData);
      int httpResponseCode = http.POST("**********");


      Serial << "httpPostRequest: " << endl <<
      "dataToSend: " << dataToSend << endl <<
      "serverName: " << serverName << endl <<
      "responsecode: " << httpResponseCode << endl << endl;
      
    http.end();   // free up resources
  }
}

thanks for showing interest

Dave

5

Your server loop is written to behave like a simple HTTP GET request parser.
It stops reading at the blank line that terminates the header:

if (c == '\n') {
    if (currentLine.length() == 0) {
        // end of request
    } else {
        ...
        break;
    }
}

This is the key:
HTTP POST requests contain a body after the blank line, but your code stops reading at the blank line and immediately replies, without reading the POST body.

Therefore:

  • The URL/path shows up correctly (because it's in the request line: POST /yourPath HTTP/1.1)
    The POST data never shows up because you never read past the headers
    The HTTPClient does send the body correctly, but your server ends reading too early
6

man thats great, thank you, as i think said in my first post not understanding fully,

you have expanded my knowledge thank you

Dave