/* ------------------------ */
/* --- mcast_example.c ---- */
/* ------------------------ */
/* can start as sender or receiver; sender sends 3 messages to each mutlicast group and receiver reads them. To compile: gcc -g mcast_example.c multicast.c -o mcast_example */

#include "multicast.h"

int CreateMcastSocket();
void sendMessage(int s);
void getMessage(int inSock);
void map_mcast_address(char * session_numb);

//char GroupIPaddress1[]="226.1.1.1";/* multicast group IP address */
char GroupIPaddress1[]="224.4.4.4";/* multicast group IP address */
char GroupIPaddress2[]="225.5.5.5";/* multicast group IP address */
int  UDPport;            /* port number */
u_char LOOP=1, TimeToLive=3;           /* ttl value */
struct in_addr localInterface;


main(int argc,char *argv[])
{
  /* parse the command line to get the multicast group address */
  if (argc < 3)
  {
    printf("Usage: %s port_number s|r [0|1]\n",argv[0]);
    exit(1);
  }
  if (argc > 4)
     LOOP= atoi(argv[3]);
  
  UDPport =  atoi(argv[1]);

  /* We need TWO Sockets for Send and Receive (WHY?) */
  if (!strcmp(argv[2],"s"))
  {
    int CMcastSock=-1;

    printf("Sending to %s and %s mcast groups...\n",GroupIPaddress1,GroupIPaddress2);
    if ((CMcastSock = socket(PF_INET,SOCK_DGRAM, 0)) < 0)
    {
      printf("can't create socket: %s \n", strerror(errno));
    exit(-1);
    }

    setTTLvalue(CMcastSock,&TimeToLive);  /* setting theTTL value */
    setLoopback(CMcastSock,LOOP);  /*0=disable,1=enable loopback; default is enable*/
    sendMessage(CMcastSock);
    close(CMcastSock);
  }
  else if (!strcmp(argv[2],"r"))     
  {
    int SMcastSock=-1;
   printf("Joining %s and %s mcast groups...\n",GroupIPaddress1,GroupIPaddress2);
    SMcastSock  = CreateMcastSocket(UDPport);
    /* OR SMcastSock  = passiveUDP(UDPport); */
    joinGroup(SMcastSock, GroupIPaddress1);
    joinGroup(SMcastSock, GroupIPaddress2);
    getMessage(SMcastSock);
    leaveGroup(SMcastSock, GroupIPaddress1);
    leaveGroup(SMcastSock, GroupIPaddress2);
    close(SMcastSock);
  }
  else 
  {
    printf("Usage: %s port_number s|r [0|1]\n",argv[0]);
    exit(1);
  }
  
}


/*
   This functions: allocates a socket for getting the group multicast messages
*/
 
int CreateMcastSocket(int port)
{
  int s,length,err;
  struct sockaddr_in groupHost; /* multicast group host info structure */

  
  /* Get the multicast group host information */
  groupHost.sin_family=AF_INET;
  groupHost.sin_port=htons(port); 
  /* wildcard address: means it may receive any unicast 
     or multicast pkts destined to this port */
  groupHost.sin_addr.s_addr = htonl(INADDR_ANY); /*unicast ot mcast packets*/
  /* OR (this is the only part missing in passiveUDP())==>
       groupHost.sin_addr.s_addr = htonl(inet_addr(GroupIPaddress1)); 
     this way this server is restricted to listen for mcast packets ONLY*/
  
  /* Allocate a UDP socket and set the multicast options */

  if ((s = socket(PF_INET,SOCK_DGRAM, 0)) < 0)
  {
    printf("can't create socket:%s \n", strerror(errno));
    exit(-1);
  }

  /* allow multipule processes to bind to same multicast port */
  reusePort(s);
  
  /* bind the UDP socket to the mcast address to recv messages from the group */
  if((bind(s,(struct sockaddr *) &groupHost, sizeof(groupHost))== -1))
  {
    printf("error in bind\n");
    exit(2);
  }
  
  return s;  
}

/* 
   This function reads the input from STDIN and sends it to the group 
*/
void 
sendMessage(int sockfd)
{
  char sendBuf[]="This is a Multicast Test Message in 224.4.4.4/4444\n";
  char sendBuf1[]="This is a Multicast Test Message in 225.5.5.5/4444\n";
  int i,bytes=0;
  struct sockaddr_in dest;

  /* send the message to the group */
  dest.sin_family = AF_INET;
  dest.sin_port =  htons(UDPport);
  dest.sin_addr.s_addr = inet_addr(GroupIPaddress1);
  
//  Setting the local interface -- new added requirement
localInterface.s_addr = INADDR_ANY;
if(setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_IF, (char *)&localInterface, sizeof(localInterface)) < 0)
{
  perror("Setting local interface error");
  exit(1);
}

  for (i=1; i<=3;i++)  
  {
    //    printf("Msg Sent:%s",sendBuf);
    dest.sin_addr.s_addr = inet_addr(GroupIPaddress1);
    if ( sendto(sockfd,sendBuf,strlen(sendBuf),0,(struct sockaddr *) &dest, sizeof(dest)) < 0 )
    {
      printf("error in sendto \n");
      exit(-1);
    }
    sleep(1);
    dest.sin_addr.s_addr = inet_addr(GroupIPaddress2);
    if ( sendto(sockfd,sendBuf1,strlen(sendBuf),0,(struct sockaddr *) &dest,
		sizeof(dest)) < 0 )
    {
      printf("error in sendto \n");
      exit(-1);
    }

  }
}

/*
   Get the multicast message sent by the group and print out to STDOUT
*/
void getMessage(int inSock)
{
  int i,bytes=0;
  char recvBuf[MAX_LEN];
  
  for (i=1; i<=6;i++)  
  {
    memset(recvBuf,'\0',MAX_LEN);
    bytes = recv(inSock,recvBuf,MAX_LEN,0);
    if (bytes < 0)
    {
      printf("error in reading from multicast socket\n");
      exit(-1);
    }
    else if(bytes == 0)
       printf("zero bytes read\n");
    else
       /* print the message to STDOUT */
    {
      if (write(1,recvBuf,bytes) < 0)
      {
	printf("error in write to STDOUT \n");
	exit(-1);
      }
    }
  }
}