multicast sender and receiver toggle

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define MAX_LEN  20

static int sock;
static int flag_on = 1;
static struct sockaddr_in multicast_addr;
static char message_received[MAX_LEN+1];
static int msgrecv_len;
static struct ip_mreq mc_req;
static char* multicast_ip="224.5.6.7";
static unsigned short multicast_port=5006;
static struct sockaddr_in from_addr;
static unsigned int from_len;

static char message_to_send[MAX_LEN];
static unsigned int send_len;
static unsigned char multicast_ttl=1;
static struct sockaddr_in multicast_addr;

int sender();
int receiver();

int sender()
{
	/* create a socket */
	if ((sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
	{
		perror("Socket creation failed");
		exit(1);
	}

	/* set the TTL (time to live/hop count) for the send */
	if ((setsockopt(sock, IPPROTO_IP, IP_MULTICAST_TTL, (void*) &multicast_ttl, sizeof(multicast_ttl))) < 0)
	{
		perror("setsockopt() failed");
		exit(1);
	}


	memset(&multicast_addr, 0, sizeof(multicast_addr));
	multicast_addr.sin_family      = AF_INET;
	multicast_addr.sin_addr.s_addr = inet_addr(multicast_ip);
	multicast_addr.sin_port        = htons(multicast_port);


//printf("Type the message below (Press Enter to send, ctrl-C to quit):\n");
printf("NOW IN STATE SENDER!\n");

memset(message_to_send, 0, sizeof(message_to_send));

//while (fgets(message_to_send, MAX_LEN, stdin))
while(1)
  {
	  //message_to_send="batman";
	  strcpy(message_to_send,"Hallo\n\0");
	  printf("message to send: %s \n", message_to_send);
    send_len = strlen(message_to_send);

		if ((sendto(sock, message_to_send, send_len, 0,
		(struct sockaddr *) &multicast_addr,
		sizeof(multicast_addr))) != send_len)
		{
			perror("Error in number of bytes");
			exit(1);
		}

    memset(message_to_send, 0, sizeof(message_to_send));
    break;
  }
  printf("//switch to receiver()\n");
  close(sock);
  receiver();
return 0;
}

int receiver()
{
	printf("NOW IN STATE RECEIVER()\n");


	if ((sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
	{
		perror("socket() failed");
		exit(1);
	}

	/* set reuse port to on to allow multiple binds per host */
	if ((setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &flag_on,
	sizeof(flag_on))) < 0)
	{
		perror("setsockopt() failed");
		exit(1);
	}

	/* construct a multicast address structure */
	memset(&multicast_addr, 0, sizeof(multicast_addr));
	multicast_addr.sin_family      = AF_INET;
	multicast_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	multicast_addr.sin_port        = htons(multicast_port);

	/* bind to multicast address to socket */
	if ((bind(sock, (struct sockaddr *) &multicast_addr, sizeof(multicast_addr))) < 0)
	{
		perror("bind() failed");
		exit(1);
	}

  /* construct an IGMP join request structure */
  mc_req.imr_multiaddr.s_addr = inet_addr(multicast_ip);
  mc_req.imr_interface.s_addr = htonl(INADDR_ANY);

  /* send an ADD MEMBERSHIP message via setsockopt */
  if ((setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP, (void*) &mc_req, sizeof(mc_req))) < 0)
    {
      perror("setsockopt() failed");
      exit(1);
    }

  while(1)
    {
      memset(message_received, 0, sizeof(message_received));
      from_len = sizeof(from_addr);
      memset(&from_addr, 0, from_len);

      /* block waiting to receive a packet */
      if ((msgrecv_len = recvfrom(sock, message_received, MAX_LEN, 0, (struct sockaddr*)&from_addr, &from_len)) < 0)
	{
	  perror("recvfrom() failed");
	  break;
	}

      printf("Received %d bytes from %s: ", msgrecv_len,	     inet_ntoa(from_addr.sin_addr));
      printf("%s", message_received);
      if(strcmp(message_received,"haha"))
      break;

    }

    printf("//switch to sender()\n");
    close(sock);
    sender();
  return 0;
}

int main(int argc, char *argv[])
{
	/*
  if ((sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
    {
      perror("socket() failed");
      exit(1);
    }

    	set the TTL (time to live/hop count) for the send
	if ((setsockopt(sock, IPPROTO_IP, IP_MULTICAST_TTL, (void*) &multicast_ttl, sizeof(multicast_ttl))) < 0)
	{
		perror("setsockopt() failed");
		exit(1);
	}

		set reuse port to on to allow multiple binds per host
	if ((setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &flag_on,
	sizeof(flag_on))) < 0)
	{
		perror("setsockopt() failed");
		exit(1);
	}

		 bind to multicast address to socket
	if ((bind(sock, (struct sockaddr *) &multicast_addr, sizeof(multicast_addr))) < 0)
	{
		perror("bind() failed");
		exit(1);
	}
	*
	* */

  sender();
  //receiver();

  return 0;
}