Programming

unsigned int buff;
socklen_t optlen;
optlen = sizeof(buff);
...
struct sockaddr sockaddr;
struct ifreq ifreq;

memset(&ifreq, 0, sizeof(ifreq));
strcpy(sockaddr.sa_data, device); /* Transmitting device is set. */
strcpy(ifreq.ifr_name, device);

if((sock = socket(AF_PACKET, SOCK_PACKET, htons(ETH_P_ALL))) < 0)
        {
        perror("socket()");
        exit(-1);
        }
if((setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, &ifreq, sizeof(ifreq))) < 0)
        {
        perror("setsockopt() cannot bind.");
        exit(-1);
        }

if((resource=getsockopt(sock, SOL_SOCKET, SO_SNDBUF, &buff, &optlen))<0)
{
perror("getsockopt()");
}

printf("Attempting to increase SNDBUF... ");
buff = 2147483647; /*MAXIMUM*/

if((resource = setsockopt(sock, SOL_SOCKET, SO_SNDBUF, &buff, 
sizeof(buff)))<0)
{
perror("setsockopt()");
} 

/*HERE'S THE TRANSMITTING PART*/

            time_t startTime;
            startTime = time(NULL);

        while(time(NULL) - startTime < (time_assigned * 60))
        {
    azimuth++;
    printf("%u\n", (unsigned int )azimuth);        
    ret= sendto(sock, &arpmsg, sizeof(struct arpmsg),0, &sockaddr,sizeof(sockaddr));

    if(ret < 0 && ret != ENOBUFS) 
        {
        perror("sendto()");
        exit(-1);
        }
        checkordersarrival();
        }

while(time(NULL) - startTime < (time_assigned * 60))
{
 retry: /*This is a label.*/
 ret = sendto(sock, &arpmsg, sizeof(struct arpmsg),0, &sockaddr,sizeof(sockaddr));

    if(ret < 0) 
        {
           if(errno == ENOBUFS)
            {
              printf("Socket ran out of buffer space.\n");
              printf("Giving it some time...\n");
              usleep(300000);
              goto retry;
             }else {
                       perror("sendto()");
                       exit(-1);
                       }
         }
        checkordersarrival();
        }
}