Receiving a HTTP POST Request on Arduino

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Is it possible to receive a HTTP Post request with my Arduino Uno using a Ethernet shield. I want to make an Android app wich can control me Arduino and I thought the best way t

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醉梦人生

2021-01-31 13:21

A POST looks like:

POST /test.php HTTP/1.1
Host: 192.168.0.55
Content-Type: application/x-www-form-urlencoded
Connection: close
User-Agent: Arduino/1.0
Content-Length: 1024

data=5

So you have to ignore first "newline" and read on. Here is my modified Web Server code to read posted data:

/*
  Web Server 
*/

#include <SPI.h>
#include <Ethernet.h>

// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
IPAddress ip(192, 168, 15, 177);

// Initialize the Ethernet server library
// with the IP address and port you want to use
// (port 80 is default for HTTP):
EthernetServer server(80);

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }


  // start the Ethernet connection and the server:
  //Ethernet.begin(mac, ip);
  Ethernet.begin(mac);
  server.begin();
  Serial.print("server is at ");
  Serial.println(Ethernet.localIP());
}


  void writeResponse(EthernetClient client) {
    // send a standard http response header
    client.println("HTTP/1.1 200 OK");
    client.println("Content-Type: text/html");
    client.println("Connection: close");  // the connection will be closed after completion of the response
    // client.println("Refresh: 5");  // refresh the page automatically every 5 sec

    client.println();
    client.println("<!DOCTYPE HTML>");
    client.println("<html> <body>");
    // output the value of each analog input pin
    for (int analogChannel = 0; analogChannel < 6; analogChannel++) {
      int sensorReading = analogRead(analogChannel);
      client.print("analog input ");
      client.print(analogChannel);
      client.print(" is ");
      client.print(sensorReading);
      client.println("<br />");
    }
    client.println("<form action=\"\" method=\"post\">");
    client.println("<input type=\"submit\" value=\"On\" name=\"btnOn\">");
    client.println("<input type=\"submit\" value=\"Off\" name=\"btnOff\">");
    client.println("</form>");
    client.println("</body> </html>");
  }

void loop() {
  // listen for incoming clients
  EthernetClient client = server.available();
  if (client) {
    Serial.print("new client [");
    //Serial.print(client.getRemoteIP());
    //Serial.println("]");

    // an http request ends with a blank line
    boolean currentLineIsBlank = true;
    String req_str = "";
    int data_length = -1;
    boolean skip = true;

    //int empty_line_count = 0;
    while (client.connected()) 
    {
      if (client.available()) {
        char c = client.read();
        //Serial.write(c);
        req_str += c;

        // if you've gotten to the end of the line (received a newline
        // character) and the line is blank, the http request has ended,
        // so you can send a reply       
        if (c == '\n' && currentLineIsBlank && req_str.startsWith("GET")) {
          writeResponse(client);
          break;
        }
        if (c == '\n' && currentLineIsBlank && req_str.startsWith("POST") && !skip) {
          writeResponse(client);
          break;
        }   
        if (c == '\n' && currentLineIsBlank && req_str.startsWith("POST") && skip) {
          skip = false;
          String temp = req_str.substring(req_str.indexOf("Content-Length:") + 15);
          temp.trim();
          //Serial.print("Content-Length=");
          data_length = temp.toInt();
          /*Serial.println(data_length);
          writeResponse(client);
          break;*/
          while(data_length-- > 0)
          {
            c = client.read();
            req_str += c;
          }
          writeResponse(client);
          break;
        }

        if (c == '\n') {
          // you're starting a new line
          currentLineIsBlank = true;
        } else if (c != '\r') {
          // you've gotten a character on the current line
          currentLineIsBlank = false;
        }
      }
    }

    Serial.println(req_str);

    // give the web browser time to receive the data
    delay(1);
    // close the connection:
    client.stop();
    Serial.println("client disconnected");
  }
}

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予麋鹿

2021-01-31 13:27

I wanted to read a POST like you instead of using a GET. I did it like this:

/*
 A simple Arduino Ethernet web server. 
 by John Harrison
 */

#include <SPI.h>
#include <Ethernet.h>

// You can change the MAC and IP addresses to suit your network:

byte mac[] = { 0X52, 0X64, 0X75, 0X69, 0X6E, 0X6F };
IPAddress ip( 192,168,0,97 );

EthernetServer server(80); // Port 80 is HTTP port
char new_state[1024];

void setup()
{
  Serial.begin(9600);
  // Start the Ethernet server:
  Ethernet.begin(mac, ip);

  server.begin();

  // Set the digital pins ready to write to
  for (int pin = 2; pin <= 9; pin++) {
    pinMode(pin, OUTPUT);
  }

  Serial.print("Serving on http://");
  Serial.println(Ethernet.localIP());
}

void loop()
{
  // listen for incoming clients
  EthernetClient client = server.available();

  if (client) {

    // Serial.println("Client connected");

    while (client.connected()) {

      int i = 0;
      int head = 1;
      int body = 0;

      while(client.available()) {
        char c = client.read();
        if (c == '\n') {

          if ( i <= 2 ) {

            // an http request ends with a blank line

            sendPage(client);
            if ( head == 1 ) {
              body = 1;
              head = 0;
            }

          }

          i = -1;

        }
        if ( body == 1 ) {
          new_state[i] = c;
        }
        i++;
        new_state[i] = '\0';
      }
      i = 0;
    }

    // Serial.println("Disconnected");
    /*
    if ( strlen(new_state) > 0 ){
      Serial.print ("[");
      Serial.print(new_state);
      Serial.println ("]");
    }
    */
    // Post data looks like pinD2=On
    if ( strncmp( new_state, "pinD", 4) == 0 ) {
      int pin = new_state[4] - 48; // Convert ascii to int
      // Serial.println(pin);
      if ( strncmp( new_state+5, "=On", 3) == 0 ) {
        digitalWrite(pin, 1);
      } 
      else if ( strncmp( new_state+5, "=Off", 4) == 0 ) {
        digitalWrite(pin, 0);
      }
    }

  }

}

void sendPage(EthernetClient client)
{

  // Serial.println("Sending response");

  // send a standard http response header
  client.println("HTTP/1.0 200 OK\Content-Type: text/html\n\n<html>\n<head>");
  client.println("<link rel='icon' href='data:;base64,iVBORw0KGgo='>");
  client.println("<title>POST Pin controller</title>\n</head>\n<body>\n");
  client.println("<h2>Buttons turn pins on or off</h2>");
  client.println("<form method='post' action='/' name='pins'>");

  char line[1024];
  int pin;

  for ( pin=2; pin<=9; pin++ ) {
    sprintf(line, "<input name='pinD%d' type='submit' value='On' />\n", pin);
    client.print(line);
    sprintf(line, "<input name='pinD%d' type='submit' value='Off' /> %d<br />\n", pin, pin);
    client.print(line);
  }

  client.println("</form>\n</body>\n</html>");
  client.stop();

}

There are ways to do it which are simpler and smaller, but I found them quite laggy so have been trying to get it as fast as possible.

I have used this to control 8 LEDs on pins 2-9 on a Mega 2560. I haven't tested it on a Uno yet, but I expect it would work the same.

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太阳男子

2021-01-31 13:27

Not sure about POST, but GET definitely works. Here's an AJAX example that I've been using that works. It just controls an RGB LED.

 xmlhttp.open("GET", "http://ipAddressOfArduino?r=" + redVal + "&g=" + greenVal + "&b=" + blueVal + "&e", true);

Then on the Arduino side, I just parse the data.

//ARDUINO 1.0+ ONLY
//ARDUINO 1.0+ ONLY


#include <Ethernet.h>
#include <SPI.h>
boolean reading = false;
String myStr;
int redVal, greenVal, blueVal;

////////////////////////////////////////////////////////////////////////
//CONFIGURE
////////////////////////////////////////////////////////////////////////
  //byte ip[] = { 192, 168, 0, 1 };   //Manual setup only
  //byte gateway[] = { 192, 168, 0, 1 }; //Manual setup only
  //byte subnet[] = { 255, 255, 255, 0 }; //Manual setup only

  // if need to change the MAC address (Very Rare)
  byte mac[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };

  EthernetServer server = EthernetServer(80); //port 80
////////////////////////////////////////////////////////////////////////

void setup(){
  Serial.begin(9600);

  pinMode(3, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);

  Ethernet.begin(mac);
  //Ethernet.begin(mac, ip); //for manual setup

  server.begin();
  Serial.println(Ethernet.localIP());

}

void loop(){

  // listen for incoming clients, and process qequest.
  checkForClient();

}

void checkForClient(){

  EthernetClient client = server.available();

  if (client) {

    // an http request ends with a blank line
    boolean currentLineIsBlank = true;
    boolean sentHeader = false;
    myStr = "";
    while (client.connected()) {
      if (client.available()) {

        char c = client.read();

        if(reading && c == ' ') reading = false;
        if(c == '?') reading = true; //found the ?, begin reading the info

        if(reading){
          //Serial.print(c);
          if (c!='?') {
            myStr += c;
          }

        }

        if (c == '\n' && currentLineIsBlank)  break;

        if (c == '\n') {
          currentLineIsBlank = true;
        }else if (c != '\r') {
          currentLineIsBlank = false;
        }
      }
    }

    parseThangs(myStr);
    analogWrite(3, redVal);
    analogWrite(5, greenVal);
    analogWrite(6, blueVal);    
    delay(100); // give the web browser time to receive the data
    client.stop(); // close the connection:    
  } 
}

void parseThangs(String str) {
  int startIndex = str.indexOf("r");
  int endIndex = str.indexOf("g");
  String redStr = str.substring(startIndex + 2, endIndex - 1);
  char tempRed[4];
  redStr.toCharArray(tempRed, sizeof(tempRed));
  redVal = atoi(tempRed);
  startIndex = str.indexOf("g");
  endIndex = str.indexOf("b");
  String greenStr = str.substring(startIndex + 2, endIndex -1);
  char tempGreen[4];
  greenStr.toCharArray(tempGreen, sizeof(tempGreen));
  greenVal = atoi(tempGreen);
  startIndex = str.indexOf("b");
  endIndex = str.indexOf("e");
  String blueStr = str.substring(startIndex + 2, endIndex -1);
  char tempBlue[4];
  blueStr.toCharArray(tempBlue, sizeof(tempBlue));
  blueVal = atoi(tempBlue);
  Serial.println(redStr + " " + greenStr + " " + blueStr);
}

Probably a little sloppy, but it works.

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