Send SMS through HTTP server

/*
  Web Server
*/

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

//SMS Include
#include <DFRobot_sim808.h>
#include <SoftwareSerial.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, 0xA2, 0xBE, 0xEF, 0xFE, 0xED
};
IPAddress ip(192, 168, 1, 23);

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

//SMS VARIABLES
#define MESSAGE_LENGTH 160
char message[MESSAGE_LENGTH];
char phone[16];
char datetime[24];
char phone_to[] = "xxxxxxx";
#define PIN_TX    12
#define PIN_RX    13
SoftwareSerial mySerial(PIN_TX,PIN_RX);
DFRobot_SIM808 sim808(&mySerial);//Connect RX,TX,PWR,


void setup() {
  // Open serial communications and wait for port to open:
  mySerial.begin(9600);
  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());

  //******** Initialize sim808 module *************
  while(!sim808.init())
  {
      Serial.print("Sim808 init error\r\n");
      delay(1000);
  }

  delay(3000);
  if( sim808.attachGPS()) {
      Serial.println("Open the GPS power success");
      //return true;
  }
  else {
      Serial.println("Open the GPS power failure");
      //return false;
  }
}

void writeResponse(EthernetClient client) {
  // send a standard http response header
  Serial.println("SMS was sent - this is in writeResponse");
  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();
  client.println("SENT");
}

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

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

    //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) {

          if(sendSms()) {
            Serial.println("SMS was sent - this is in loop");
            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");
  }
}

bool sendSms() {
  char msg[] = "test";
  sim808.sendSMS(phone_to,msg);
  //************* Turn off the GPS power ************
  sim808.detachGPS();
  Serial.println("SMS was sent - this is in function");
  return true;
}