Socket broadcast

[silviagonzalez]

Hello

I have the next net.

I execute the tcpdump -X -i br0, with th next result.

but, When I execute my program to receive the mesage, I don't receive any messsage. My program is the next.

int main(int argc, char *argv[]) {

struct sockaddr_in server;
uint16_t *buf2=malloc(1 * sizeof(uint16_t));
/* Create socket for sending/receiving datagrams */
  if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
  perror("socket() failed");

  /* allow broadcast messages for the socket */
   int true = 1;
   rc=setsockopt(sock, SOL_SOCKET, SO_BROADCAST, &true, sizeof(true));

     /* Construct local address structure */
     memset(&broadcastAddr, 0, sizeof(broadcastAddr));   /* Zero out structure */
     broadcastAddr.sin_family = AF_INET; /* Internet address family */
     broadcastAddr.sin_addr.s_addr = htonl(INADDR_ANY);

    broadcastAddr.sin_port = htons(1000);      /* Broadcast port */

     localIPLen = sizeof(uint16_t);  /* Find length of localIP */

     mess=recvfrom(sock, buf2, localIPLen , 0, (struct sockaddr *) &broadcastAddr, sizeof(broadcastAddr)); 

  }

I can't find the error. Can anyone help me.

Thanks.

[alejandrolozan1]

Hi,

it seems to be ok, but after comparing the code agains other examples the only difference I could find was the binding of the socket to a port.

Have you tried that?

Alejandro

[silviagonzalez]

Hello

I did it, this is not my problem.

Now it works fine I resolved my problem, with the next code.

int main(){

    int saddr_size , data_size,i;

    struct sockaddr saddr;        

    uint16_t *buffer = (uint16_t *) malloc(65536);

    printf("Starting...\n");

    int sock_raw = socket( AF_PACKET , SOCK_RAW , htons(ETH_P_ALL)) ;    

    saddr_size = sizeof saddr;

    data_size = recvfrom(sock_raw , buffer , 65536 , 0 , &saddr , (socklen_t*)&saddr_size);

   for (i=0;i<=data_size;){

      printf("Data %02x\t%02x\t%02x\t%02x\t\t  %c%c%c%c\n",buffer[i], buffer[i+1], buffer[i+2], buffer[i+3],buffer[i], buffer[i+1], buffer[i+2], buffer[i+3]);

       i=i+4;

   }   

    close(sock_raw);

    return 0;

}

Thanks.