/*
NAME:       multicasr receiver
SYNOPSIS:    McastRcv <name> <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 <stdlib.h>
#include <string.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 "packetReg.h"

int main( int argc, char * argv[] )
{
  int   s;
  struct sockaddr_in mc_group;
  struct sockaddr_in from;
  int fromlen;
  int length;
  Packet pkt;
  int rc, n;
  struct ip_mreq mreq;  /* multicast group info structure */
   /* linux */
   unsigned long int mcGroup;
   /* Solaris
      in_addr_t mcGroup; */
  int reuse;
  char loop, ttl;
  fd_set readfds, readfdsCopy;
  
  if (argc != 4) {
    fprintf(stderr, "Usage : %s <name> <multicast group> <port>\n",argv[0]);
    exit(0);
  }
  
  s = socket (PF_INET,SOCK_DGRAM,0); 
  
  /* Set socket to receive datagrams */
  reuse=1;
  if ( setsockopt(s ,SOL_SOCKET,SO_REUSEADDR,
		  (char *) &reuse,sizeof(reuse)) == -1 ){
    printf("error in setsockopt,SO_REUSEPORT \n");
    exit(-1);
  }
  
  mc_group.sin_family = AF_INET;
  mc_group.sin_addr.s_addr = INADDR_ANY;
  mc_group.sin_port = htons(atoi(argv[3]));  
  if (bind( s, (struct sockaddr *)&mc_group, sizeof(mc_group)) < 0) {
    fprintf(stderr, "Can't bind ....\n");
    exit (-1);
  }
  
  /* Join Multicast Group */
  if( (mcGroup = inet_addr(argv[2]))== -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);
  }
  /* Set socket to send datagrams */
  mc_group.sin_addr.s_addr= mcGroup;
  loop = 1;
  if( setsockopt(s, IPPROTO_IP,IP_MULTICAST_LOOP,(char *) &loop,
		 sizeof(u_char)) == -1 )   {
    printf("error in setting loopback\n");
  }
  ttl = 5;
  if( setsockopt(s ,IPPROTO_IP,IP_MULTICAST_TTL,(char *) &ttl,
		 sizeof(u_char)) == -1 )   {
    printf("error in setting loopback value\n");
  }
   
  FD_ZERO(&readfdsCopy);
  FD_SET(s,&readfdsCopy);
  FD_SET(0,&readfdsCopy); 
  for(;;){
    memcpy(&readfds, &readfdsCopy, sizeof(fd_set));
    n = select(FD_SETSIZE, &readfds, (fd_set *) 0, (fd_set *) 0, NULL);
    if (n > 0) {
      if (FD_ISSET(s, &readfds)) {
	fromlen = sizeof(from);
	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 \n", pkt.name, pkt.msg);
	  if (strncmp(pkt.msg, "STOP", 4)== 0) 
	      break;
	}
      }
      if (FD_ISSET(0, &readfds)) {
	rc=read(0,pkt.msg, BUFSIZE);
	if (rc == 0) break;
	strcpy(pkt.name, argv[1]);
	pkt.msg[rc-1]='\0';
	pkt.length = sizeof(pkt)-BUFSIZE+rc;
	printf("Sending %d bytes \"%s\"\n", pkt.length, pkt.msg);
	if (sendto(s, (char *)&pkt, pkt.length, 0, (struct sockaddr*)&mc_group, 
		   sizeof(mc_group)) <0 )
	    perror("sending datagram message");
      }
    }
  }
  
  /* 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);
  }
}