/*
NAME:       multicasr receiver
SYNOPSIS:    McastRcv <multicast group> <port>
DESCRIPTION:    The program creates a datagram socket and joins a multicast
                group. It prints on the standard output all received message.
*/

#include <stdio.h>
#include <errno.h>
#include <sys/time.h>

#include <sys/param.h>
#include <sys/socket.h>
#include <sys/file.h>

#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <stdlib.h>

#include "packetReg.h"

int main( int argc, char * argv[] )
{
   int   s;
   struct   sockaddr_in server;
   struct sockaddr_in from;
   int fromlen;
   int length;
   Packet pkt;
   int rc;
   struct ip_mreq mreq;  /* multicast group info structure */
   /* linux */
   unsigned long int mcGroup;
   /* Solaris
      in_addr_t mcGroup; */
   int reuse;

   if (argc != 3) {
     fprintf(stderr, "Usage : %s <multicast group> <port>\n",argv[0]);
     exit(0);
   }
   s = socket (PF_INET,SOCK_DGRAM,0); 

   reuse=1;
   if ( setsockopt(s,SOL_SOCKET,SO_REUSEADDR,
		   (char *) &reuse,sizeof(reuse)) == -1 ){
     printf("error in setsockopt,SO_REUSEPORT \n");
     exit(-1);
   }
   
   server.sin_family = AF_INET;
   server.sin_addr.s_addr = htonl(INADDR_ANY);
   server.sin_port = htons(atoi(argv[2]));  
   if (bind( s, (struct sockaddr *)&server, sizeof(server)) < 0) {
     fprintf(stderr, "Can't bind ....\n");
     exit (-1);
   }
   
   /* Join Multicast Group */
   if( (mcGroup = inet_addr(argv[1]))== -1)
       printf("error in inet_addr\n");
   
   mreq.imr_multiaddr.s_addr = mcGroup;
   mreq.imr_interface.s_addr = INADDR_ANY;
   
   if ( setsockopt(s,IPPROTO_IP,IP_ADD_MEMBERSHIP,(char *) &mreq,
		   sizeof(mreq)) == -1 )
   {
     printf("error in joining group \n");
     exit(-1);
   }

/*  get data from group and send it back */
   for(;;){
     fromlen = sizeof(from);
     printf("\n...server is waiting...\n");
     if ((rc=recvfrom(s, (char *)&pkt, sizeof(pkt), 0, 
		      (struct sockaddr *)&from, 
		      &fromlen)) < 0)
         perror("receiving datagram  message");
     if (rc > 0){
       printf("From %s:%d, %d bytes received\n", inet_ntoa(from.sin_addr),
	      ntohs(from.sin_port), pkt.length);
       printf("%s wrote : %s ", pkt.name, pkt.msg);
       if (strncmp(pkt.msg, "STOP", 4)== 0) 
	 break;
     }
   }
   
   /* Leave multicast group */
   mreq.imr_multiaddr.s_addr = mcGroup;
   mreq.imr_interface.s_addr = INADDR_ANY;
  
  if( setsockopt(s,IPPROTO_IP,IP_DROP_MEMBERSHIP,
                (char *) &mreq,sizeof(mreq)) == -1 )
  {
    printf("error in leaving group \n");
    exit(-1);
  }
}