// programa servidor8.cpp - Servidor que lê e escreve em um vetor de caracter
// Protocolo UDP

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


#define MULTICAST_ADDR "225.0.0.37"


int main( )
{
   int server_sockfd, client_sockfd;
   size_t server_len;
   socklen_t client_len;
   struct sockaddr_in server_address;
   struct sockaddr_in client_address;
   
   struct ip_mreq mreq;  // para endereço multicast

   unsigned short porta = 9734;

   unlink("server_socket");  // remocao de socket antigo
   if ( (server_sockfd = socket(AF_INET, SOCK_DGRAM, 0) )  < 0  )  // cria um novo socket
     {
       printf(" Houve erro na ebertura do socket ");
       exit(1);
     }
   server_address.sin_family = AF_INET;
   server_address.sin_addr.s_addr = htonl(INADDR_ANY);
   server_address.sin_port = htons(porta);
 

   server_len = sizeof(server_address);
  
   if(  bind(server_sockfd, (struct sockaddr *) &server_address, server_len) < 0 )
    {
      perror("Houve error no Bind");
      exit(1);
    }


   // use setsockopt() para requerer inscrição num grupo multicast
     mreq.imr_multiaddr.s_addr=inet_addr(MULTICAST_ADDR);
     mreq.imr_interface.s_addr=htonl(INADDR_ANY);
     if (setsockopt(server_sockfd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mreq,sizeof(mreq)) < 0) {
	  perror("setsockopt");
	  exit(1);
     }
     printf(" IPPROTO_IP = %d\n", IPPROTO_IP);
     printf(" SOL_SOCKET = %d\n", SOL_SOCKET);
     printf(" IP_ADD_MEMBERSHIP = %d \n", IP_ADD_MEMBERSHIP);


   while(1){
      int valor;

      printf("Servidor esperando ...\n");
    
      client_len = sizeof(client_address);
      if(recvfrom(server_sockfd, &valor, sizeof(valor),0,
          (struct sockaddr *) &client_address, &client_len) < 0 )
	{
          perror(" erro no RECVFROM( )");
          exit(1);
        } 
      printf(" Valor recebido foi = %d\n", valor);
     // close(server_sockfd);
   
   }
}