#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

typedef struct sockaddr_in SockAddr_in;
typedef struct sockaddr SockAddr;

void handle_error(char *txt)
{
    perror(txt);
    exit(-1);
}

int main()
{
    int socket_fd;
    if ((socket_fd = socket(PF_INET, SOCK_DGRAM, 0)) == -1)
        handle_error("socket");

    SockAddr_in caddr;
    SockAddr_in saddr;
    socklen_t addr_size = sizeof(SockAddr_in);
    memset(&saddr, 0, addr_size);
    saddr.sin_port = htons(4040);
    saddr.sin_family = PF_INET;
    inet_pton(PF_INET, "127.0.0.1", &(saddr.sin_addr.s_addr));

    memset(&caddr, 0, addr_size);
    caddr.sin_port = htons(4041);
    caddr.sin_family = PF_INET;
    caddr.sin_addr.s_addr = INADDR_ANY;
    inet_pton(PF_INET, "127.0.0.1", &(caddr.sin_addr.s_addr));

    if (bind(socket_fd, (SockAddr *)&caddr, addr_size) == -1)
        handle_error("bind");

    double dd = 21.21;
    if (sendto(socket_fd, &dd, sizeof(double), 0, (SockAddr *)&saddr, addr_size) == -1)
        handle_error("sendto");
    printf("sent: %f\n", dd);

    dd = 111.1;
    if (sendto(socket_fd, &dd, sizeof(double), 0, (SockAddr *)&saddr, addr_size) == -1)
        handle_error("sendto");
    printf("sent: %f\n", dd);

    dd = 321.1;
    if (sendto(socket_fd, &dd, sizeof(double), 0, (SockAddr *)&saddr, addr_size) == -1)
        handle_error("sendto");
    printf("sent: %f\n", dd);

    if (close(socket_fd) == -1)
        handle_error("close");

    return 0;
}