//
// Simple sender.c program for UDP
//
// Adapted from:
// http://ntrg.cs.tcd.ie/undergrad/4ba2/multicast/antony/example.html
//
// Changes:
// * Compiles for Windows as well as Linux
// * Takes the port and group on the command line
//
// Note that what this program does should be equivalent to NETCAT:
//
//     echo "Hello World" | nc -u 239.255.255.250 1900

#ifdef _WIN32
    #include <Winsock2.h> // before Windows.h, else Winsock 1 conflict
    #include <Ws2tcpip.h> // needed for ip_mreq definition for multicast
    #include <Windows.h>
#pragma comment(lib,"ws2_32.lib")
#else
    #include <sys/types.h>
    #include <sys/socket.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>
    #include <unistd.h> // for sleep()
#endif

#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#define MSGBUFSIZE 256
int main(int argc, char *argv[])
{
    if (argc != 3) {
       printf("Command line args should be multicast group and port\n");
       printf("(e.g. for SSDP, `sender 239.255.255.250 1900`)\n");
       return 1;
    }

    char* group = argv[1]; // e.g. 239.255.255.250 for SSDP
    int port = atoi(argv[2]); // 0 if error, which is an invalid port

    // !!! If test requires, make these configurable via args
    //
    const int delay_secs = 1;
    char message[MSGBUFSIZE];

#ifdef _WIN32
    //
    // Initialize Windows Socket API with given VERSION.
    //
    WSADATA wsaData;
    if (WSAStartup(0x0101, &wsaData)) {
        perror("WSAStartup");
        return 1;
    }
#endif

    // create what looks like an ordinary UDP socket
    //
    int fd = socket(AF_INET, SOCK_DGRAM, 0);
    if (fd < 0) {
        perror("socket");
        return 1;
    }

    // set up destination address
    //
    struct sockaddr_in addr;
    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = inet_addr(group);
    addr.sin_port = htons(port);

      // now just sendto() our destination!
    //
printf("?:");
    while (gets(message)!='\0') {
        char ch = 0;
        int nbytes = sendto(
            fd,
            message,
            strlen(message),
            0,
            (struct sockaddr*) &addr,
            sizeof(addr)
        );
        if (nbytes < 0) {
            perror("sendto");
            return 1;
        }

     #ifdef _WIN32
          Sleep(delay_secs * 1000); // Windows Sleep is milliseconds
     #else
          sleep(delay_secs); // Unix sleep is seconds
     #endif
     }

#ifdef _WIN32
    //
    // Program never actually gets here due to infinite loop that has to be
    // canceled, but since people on the internet wind up using examples
    // they find at random in their own code it's good to show what shutting
    // down cleanly would look like.
    //
    WSACleanup();
#endif

    return 0;
}