/////////////////////////////////////////////////////////////////////////////
// Rev 11/12/2003                                               
// 
// 
//                         RECVMULTICAST.C
//                         ---------------
// 
// 
// Sylvain MARECHAL - sylvain.marechal1@libertysurf.fr
/////////////////////////////////////////////////////////////////////////////
// 
//Receiving an IP Multicast Datagram Sample
//The following sample application shows how to receive an IP multicast datagram.
// 
/////////////////////////////////////////////////////////////////////////////

#ifdef _WIN32

#include <stdio.h> 
#include <winsock.h>

#else

#include <stdio.h>          /* printf(), snprintf() */
#include <stdlib.h>         /* strtol(), exit() */
#include <sys/types.h>
#include <sys/socket.h>     /* socket(), setsockopt(), bind(), 
                                         recvfrom(), sendto() */
#include <errno.h>          /* perror() */
#include <netinet/in.h>     /* IPPROTO_IP, sockaddr_in, htons(), 
                                         htonl() */
#include <arpa/inet.h>      /* inet_addr() */
#include <unistd.h>         /* fork(), sleep() */
#include <sys/utsname.h>    /* uname() */
#include <string.h>         /* memset() */


#define SOCKET int
#define FAR
#define FALSE	0
#define TRUE	1
#define INVALID_SOCKET	-1
#define SOCKET_ERROR	-1
#define SOCKADDR_IN		struct sockaddr_in
#define closesocket	close
#endif



#ifdef _WIN32
#define SOCKET_ERRNO	WSAGetLastError()
#else
#define SOCKET_ERRNO	errno
#endif

#define RECV_IP_ADDR      "234.5.6.7"     
#define DEST_PORT         4567            










int main()
{
  int index = 0,                      // Integer index
      iRecvLen, cb;                       // Length of recv_sin
  char szMessage[100];               // ASCII string 

  SOCKET Sock = INVALID_SOCKET;       // Datagram window socket

  struct ip_mreq mreq;                // Used in adding or dropping 
                                      // multicasting addresses
  SOCKADDR_IN local_sin,              // Local socket's address
              recv_sin;               // Holds the source address upon 
                                      // recvfrom function returns
#ifdef _WIN32
  WSADATA WSAData;                    // Contains details of the 
                                      // Winsock implementation
    
  // Initialize Winsock. 
  if (WSAStartup (MAKEWORD(1,1), &WSAData) != 0) 
  {
    printf( "WSAStartup failed! Error: %d\n", SOCKET_ERRNO);
    return FALSE;
  }
#endif

  // Create a datagram socket, Sock.
  if ((Sock = socket (AF_INET, SOCK_DGRAM, 0)) == INVALID_SOCKET) 
  {
    printf( "Allocating socket failed! Error: %d\n", SOCKET_ERRNO);
    return FALSE;
  }

  // Fill out the local socket's address information.
  local_sin.sin_family = AF_INET;
  local_sin.sin_port = htons (DEST_PORT);  
  local_sin.sin_addr.s_addr = htonl (INADDR_ANY);

  // Associate the local address with Sock.
  if (bind (Sock, 
            (struct sockaddr FAR *) &local_sin, 
            sizeof (local_sin)) == SOCKET_ERROR) 
  {
    printf( "Binding socket failed! Error: %d\n", SOCKET_ERRNO);
    closesocket (Sock);
    return FALSE;
  }

  // Join the multicast group from which to receive datagrams.
  mreq.imr_multiaddr.s_addr = inet_addr (RECV_IP_ADDR);
  mreq.imr_interface.s_addr = INADDR_ANY;

  if (setsockopt (Sock, 
                  IPPROTO_IP, 
                  IP_ADD_MEMBERSHIP, 
                  (char FAR *)&mreq, 
                  sizeof (mreq)) == SOCKET_ERROR)
  {
    printf( "setsockopt failed! Error: %d\n", SOCKET_ERRNO);
    closesocket (Sock);
    return FALSE;
  }

  iRecvLen = sizeof (recv_sin);
  
  // Receive data from the multicasting group server.
  if( (cb = recvfrom (Sock, 
                szMessage,
                100,         
                0,
                (struct sockaddr FAR *) &recv_sin,
                &iRecvLen)) == SOCKET_ERROR)
  {
    printf( "recvfrom failed! Error: %d\n", SOCKET_ERRNO);
    closesocket (Sock);
    return FALSE;
  }
  else
  {
    
      szMessage[cb] = 0;
      printf( szMessage );
  }

  // Disable receiving on Sock before closing it.
  shutdown (Sock, 0x00);

  // Close Sock.
  closesocket (Sock);

  return TRUE;
}