multiCastServer.c

#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <netinet/ip.h>
#include <unistd.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
        int sock, nbytes, flags, addrlen, size, i, n, iPort;
        struct sockaddr_in server, from;
        char group[12], port[6], buffer[500];
        u_char ttl;

        if(argc != 2)
        {
                printf("%d ", argc);
                printf("Expected one command, group number, to be passed to program\n");
                return -1;
        }
        strcpy(group, "239.10.5.");
        strcat(group, argv[1]);
        //Take the port in from the command line
        memset(port, '\0', sizeof(port));
        memset(port, '2', sizeof(char) * 3);
        strcat(port, argv[1]);
        //Creat socket
        sock = socket(AF_INET, SOCK_DGRAM, 0);
        if(sock < 0)
        {
                printf("Socket result: %d", sock);
                return -1;
        }
        memset(buffer, '\0', sizeof(buffer));
        ttl = 250;
        iPort = atoi(port);
        server.sin_port = htons(iPort);
        //Bind the socket to the server
        /*i = bind(sock, (struct sockaddr *) &server, sizeof(server));
        if(i < 0)
        {
                printf("Bind result: %d\n", i);
                return -1;
        }*/
        //Set the socket to be a multicast socket
        setsockopt(sock, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
        //Set server structure information
        server.sin_family = AF_INET;
        server.sin_addr.s_addr = inet_addr(group);
        //If the bind didn't fail then the server is ready to recieve a message
        printf("Multicast UDP is ready\n\n");
        //Set some variables for the recvfrom call
        addrlen = sizeof(from);
        nbytes = 500;
        flags = 0;
        n = 0;
        while(1)
        {
                //Recieve a message, setting the bytes recieve to size, and 
                //storing the message at buffer
                sprintf(buffer, "This is message %d from Group %s beacon\n", n, argv[1]);
                size = sendto(sock, buffer, sizeof(buffer), flags,
                                (struct sockaddr *) &server, sizeof(server));
                if(size < 0)
                {
                        perror("Sendto");
                        exit(1);
                }
                printf("Message sent: %s\n", buffer);
                n++;
                sleep(1);
        }
        close(sock);
}