/*                                                                             */
/* This program is the same as the broadcast receiver except that it includes  */
/* a nonblocking socket.  Unfortunately, WinSock does not have the fcntl       */
/* function so we use the ioctlsocket() to set for nonblocking.  This function */
/* is the analog of the UNIX ioctl() function.                                 */

#include <stdio.h>      /* for printf(), fprintf() */
#include <winsock.h>    /* for socket(),... */
#include <stdlib.h>     /* for exit() */

#define MAXRECVSTRING 255  /* Longest string to receive */

void DieWithError(char *errorMessage);  /* External error handling function */

int main(int argc, char *argv[])
{
    int sock;                         /* Socket */
    struct sockaddr_in broadcastAddr; /* Broadcast Address */
    unsigned short broadcastPort;     /* Port */
    char recvString[MAXRECVSTRING+1]; /* Buffer for received string */
    int recvStringLen;                /* Length of received string */
    WSADATA wsaData;                  /* Structure for WinSock setup communication */
    unsigned long nonblocking = 1;    /* Flag to make socket nonblocking */

    if (argc != 2)    /* Test for correct number of arguments */
    {
        fprintf(stderr,"Usage: %s <Broadcast Port>\n", argv[0]);
        exit(1);
    }

    broadcastPort = atoi(argv[1]);   /* first arg: broadcast port */

    if (WSAStartup(MAKEWORD(2, 0), &wsaData) != 0) /* Load Winsock 2.0 DLL */
    {
        fprintf(stderr, "WSAStartup() failed");
        exit(1);
    }

    /* Create a best-effort datagram socket using UDP */
    if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
        DieWithError("socket() failed");

    /* Set the socket to nonblocking */
    if (ioctlsocket(sock, FIONBIO, &nonblocking) != 0)
        DieWithError("ioctlsocket() failed");

    /* Construct bind 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);  /* Any incoming interface */
    broadcastAddr.sin_port = htons(broadcastPort);      /* Broadcast port */

    /* Bind to the broadcast port */
    if (bind(sock, (struct sockaddr *) &broadcastAddr, sizeof(broadcastAddr)) < 0)
        DieWithError("bind() failed");

    /* Receive a single datagram from the server */
    for (;;)
    {
        if ((recvStringLen = recvfrom(sock, recvString, MAXRECVSTRING, 0, NULL, 0)) < 0)
        {
            if (WSAGetLastError() != WSAEWOULDBLOCK)
                DieWithError("recvfrom() failed");
            else
            {
                printf("Still have not received packet...Waiting and then trying again\n");
                Sleep(2000);  /* Sleep for 2 milliseconds */
            }
        }
        else
            break;
    }

    recvString[recvStringLen] = '\0';
    printf("Received: %s\n", recvString);    /* Print the received string */

    closesocket(sock);
    WSACleanup();   /* Cleanup Winsock */

    exit(0);
}