#include <stdio.h>
#include <stdlib.h> // for atoi()
#include <winsock2.h>
#include <winsock.h>

#define PROTOPORT 5193 //default protocol port number
#define QLEN 6 // size of request queue

void ErrorHandler (char *errorMessage) {
printf (errorMessage);
}

void ClearWinSock() {
WSACleanup ();
}


int main (int argc, char *argv[]) {
int port;
if (argc>1) {
    port = atoi (argv[1]); //if argument specified convert argument to binary
}
else
	port = PROTOPORT; //use dafault port number
if (port < 0) {
	printf ("bad port number %s \n", argv[1]);
return 0;
}


WSADATA wsaData;
int iResult = WSAStartup (MAKEWORD(2,2), &wsaData);

if (iResult != 0) {
	ErrorHandler ("Error at WSAStartup()\n");
	return 0;
}


// CREAZIONE DELLA SOCKET
int MySocket;
MySocket = socket (PF_INET, SOCK_STREAM, IPPROTO_TCP);
if (MySocket < 0) {
	ErrorHandler ("socket creation failed.\n");
	ClearWinSock();
	return 0;
}

// ASSEGNAZIONE DI UN INDIRIZZO ALLA SOCKET
struct sockaddr_in sad;
memset (&sad, 0, sizeof (sad)); //ensures that extra bytes contain 0
sad.sin_family = AF_INET;
sad.sin_addr.s_addr = inet_addr ("127.0.0.1");
sad.sin_port = htons (port); //host to network short


//Assegnazione porta e ip alla socket e verifica presenza di eventuali errori
if (bind (MySocket, (struct sockaddr*) & sad, sizeof (sad)) < 0) {
	ErrorHandler ("bind() failed.\n");
	closesocket (MySocket);
	ClearWinSock ();
	return 0;
}


// SETTAGGIO DELLA SOCKET ALL'ASCOLTO
if (listen (MySocket, QLEN) < 0) {
	ErrorHandler ("listen() failed.\n");
	closesocket (MySocket);
	ClearWinSock ();
	return 0;
}

// ACCETTARE UNA NUOVA CONNESSIONE
struct sockaddr_in cad; //structure for the client address
int clientSocket; // socket descriptor for the client
int clientLen; //the size of the client address
printf ("Waiting for a client to connect...");
while (1) {
	clientLen = sizeof (cad); //set the size of the client address
	if ((clientSocket = accept (MySocket, (struct sockaddr*) &cad, &clientLen)) < 0) {
		ErrorHandler ("accept() failed.\n");

		// CHIUSURA DELLA CONNESSIONE
		closesocket (MySocket);
		ClearWinSock ();
		return 0;
	}
	printf ("Handling client %s\n", inet_ntoa (cad.sin_addr));
}
}