Arduino HTTP Server example

#include <spi.h>
#include <ethernet.h>
 
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
IPAddress ip(192, 168, 1, 130); // Arduino IP Add
EthernetServer server(80); // Web server
 
// Http data
String reqData; // Request from Smartphone
String header;
int contentSize = -1;
String CONTENT_LENGTH_TXT = "Content-Length: ";
 
void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(3, OUTPUT); // Set Pin 3 to OUTPUT Mode
  Serial.print("Ready...");
  //
  Ethernet.begin(mac, ip); 
  server.begin(); 
}
 
void loop() {
  EthernetClient client = server.available(); // Is there a client (Our Android smartphone)
   
  if (client) {
    // Let's start reading
    boolean isLastLine = true;
    boolean isBody = false;
    header = "";
    reqData = "";
    int contentLen = 0;
     
    Serial.print("Client connected!");
    while (client.connected()) {
            if (client.available()) {
              // Read data
              char c = client.read();
              
              // Serial.print(c);
                
              if (contentSize == contentLen) {
               // Serial.println("Body ["+reqData+"]");
                 
                int idx = reqData.indexOf(":");
                String status = reqData.substring(idx + 1, idx + 2);
                Serial.println("Status : " + status);
                if (status.equals("1")) {
                  digitalWrite(3, HIGH);
                }
                else {
                  digitalWrite(3, LOW);
                }
                 
                client.println("HTTP/1.1 200 OK");
                client.println("Content-Type: text/html");
                client.println("Connection: close");
                client.println();
                // send web page
                client.println("");
                client.println("");
                delay(1);
                break;
              }
               
               
              if (c == '\n' && isLastLine) {
                  isBody = true;
                  int pos = header.indexOf(CONTENT_LENGTH_TXT);
                  String tmp = header.substring(pos, header.length());
                  //Serial.println("Tmp ["+tmp+"]");
                  int pos1 = tmp.indexOf("\r\n");
                  String size = tmp.substring(CONTENT_LENGTH_TXT.length(), pos1);
                  Serial.println("Size ["+size+"]");
                  contentSize = size.toInt();
                   
              }
               
              if (isBody) {
                reqData += c;
                contentLen++;
              }
              else {
               header += c;
              }
              
               
              if (c == '\n' ) {
               isLastLine = true;
              }
              else if (c != '\r' ) {
                isLastLine = false;
              }
               
              
               
            }
    }
     
    // Close connection
    Serial.println("Stop..");
    client.stop();
  }
}