#include <windows.h> 
#include <stdio.h> 
#include "winsock2.h" 
 
#define DATA_BUFSIZE 4096 
 
void main() { 
  //----------------------------------------- 
  // Declare and initialize variables 
  WSABUF DataBuf; 
  char buffer[DATA_BUFSIZE]; 
  DWORD EventTotal = 0,  
    RecvBytes = 0,  
    Flags = 0,  
    BytesTransferred = 0,  
    CallBack = 0; 
  WSAEVENT EventArray[WSA_MAXIMUM_WAIT_EVENTS]; 
  WSAOVERLAPPED AcceptOverlapped; 
  SOCKET ListenSocket, AcceptSocket; 
 
  //----------------------------------------- 
  // Initialize Winsock 
  WSADATA wsaData; 
  WSAStartup(MAKEWORD(2,2), &wsaData); 
 
  //----------------------------------------- 
  // Create a listening socket bound to a local 
  // IP address and the port specified 
  ListenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); 
  u_short port = 27015; 
  char* ip; 
  sockaddr_in service; 
  service.sin_family = AF_INET; 
  service.sin_port = htons(port); 
  hostent* thisHost; 
  thisHost = gethostbyname(""); 
  ip = inet_ntoa (*(struct in_addr *)*thisHost->h_addr_list); 
     
  service.sin_addr.s_addr = inet_addr(ip); 
 
  //----------------------------------------- 
  // Bind the listening socket to the local IP address 
  // and port number 
  bind(ListenSocket, (SOCKADDR *) &service, sizeof(SOCKADDR)); 
 
  //----------------------------------------- 
  // Set the socket to listen for incoming 
  // connection requests 
  listen(ListenSocket, 1); 
  printf("Listening...\n"); 
 
  //----------------------------------------- 
  // Accept and incoming connection request 
  AcceptSocket = accept(ListenSocket, NULL, NULL); 
  printf("Client Accepted...\n"); 
 
  //----------------------------------------- 
  // Create an event handle and setup an overlapped structure. 
  EventArray[EventTotal] = WSACreateEvent(); 
  ZeroMemory(&AcceptOverlapped, sizeof(WSAOVERLAPPED)); 
  AcceptOverlapped.hEvent = EventArray[EventTotal]; 
  DataBuf.len = DATA_BUFSIZE; 
  DataBuf.buf = buffer; 
  EventTotal++; 
 
  //----------------------------------------- 
  // Call WSARecv to receive data into DataBuf on  
  // the accepted socket in overlapped I/O mode 
  if (WSARecv(AcceptSocket, &DataBuf, 1, &RecvBytes, &Flags, &AcceptOverlapped, NULL) == SOCKET_ERROR) { 
    if (WSAGetLastError() != WSA_IO_PENDING) 
      printf("Error occurred at WSARecv()\n"); 
  } 
 
  //----------------------------------------- 
  // Process overlapped receives on the socket 
  while (1) { 
    DWORD Index; 
 
    //----------------------------------------- 
    // Wait for the overlapped I/O call to complete 
    Index = WSAWaitForMultipleEvents(EventTotal, EventArray, FALSE, WSA_INFINITE, FALSE); 
 
    //----------------------------------------- 
    // Reset the signaled event 
    WSAResetEvent(EventArray[Index - WSA_WAIT_EVENT_0]); 
 
    //----------------------------------------- 
    // Determine the status of the overlapped event 
    WSAGetOverlappedResult(AcceptSocket, &AcceptOverlapped, &BytesTransferred, FALSE, &Flags); 
 
    //----------------------------------------- 
    // If the connection has been closed, close the accepted socket 
    if (BytesTransferred == 0) { 
      printf("Closing Socket %d\n", AcceptSocket); 
      closesocket(AcceptSocket); 
      WSACloseEvent(EventArray[Index - WSA_WAIT_EVENT_0]); 
      return; 
    } 
 
    //----------------------------------------- 
    // If data has been received, echo the received data 
    // from DataBuf back to the client 
    if (WSASend(AcceptSocket, &DataBuf, 1, &RecvBytes, Flags, &AcceptOverlapped, NULL) == SOCKET_ERROR) 
      printf("WSASend() is busted\n"); 
 
    //-----------------------------------------         
    // Reset the changed flags and overlapped structure 
    Flags = 0; 
    ZeroMemory(&AcceptOverlapped, sizeof(WSAOVERLAPPED)); 
 
    AcceptOverlapped.hEvent = EventArray[Index - WSA_WAIT_EVENT_0]; 
 
    //----------------------------------------- 
    // Reset the data buffer 
    DataBuf.len = DATA_BUFSIZE; 
    DataBuf.buf = buffer; 
  } 
}