/* 
  multicast datagram test listener
*/

#include<stdio.h>
#include<stdlib.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<netdb.h>
#include<fcntl.h>
#include<strings.h>
#include<net/if.h>

#define BPORT 53000

int main(int argc, char** peer)  // peer = bport
{
  int sockfd, x, y,result, plen, mlen, blen;
  unsigned char buffer[512];   // send buffer
  unsigned char rcvbuff[512];  // receive buffer
  struct sockaddr_in peeraddr;  // used by sendto
  struct sockaddr_in raddr;    // used by recvfrom
  struct ip_mreq mreq;  
  unsigned char uc;

  sockfd = socket(AF_INET,SOCK_DGRAM,0);

  raddr.sin_family = AF_INET;
  raddr.sin_addr.s_addr = inet_addr("224.0.0.146");
  raddr.sin_port = htons(atoi(peer[1]));
  plen = sizeof(peeraddr);  mlen = sizeof(raddr);

  bind(sockfd,(struct sockaddr*)&raddr,mlen);

  memcpy(&mreq.imr_multiaddr,&raddr.sin_addr,sizeof(raddr.sin_addr));
  mreq.imr_interface.s_addr = htonl(INADDR_ANY);
  setsockopt(sockfd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mreq,sizeof(mreq));

  uc = 1;
  setsockopt(sockfd,IPPROTO_IP,IP_MULTICAST_TTL,&uc,sizeof(uc));
  uc = 1;
  setsockopt(sockfd,IPPROTO_IP,IP_MULTICAST_LOOP,&uc,sizeof(uc));

  sprintf(buffer,"hello");
    result = recvfrom(sockfd,rcvbuff,512,0,(struct sockaddr*)&peeraddr,&plen);
  result = sendto(sockfd,buffer,strlen(buffer)+1,0,
		  (struct sockaddr*)&peeraddr,plen);
  close(sockfd);
  exit(0);
} // main