#include <sys/socket.h>

#include <sys/types.h>

int recvfrom(int s, void *buf, size_t len, int flags, 
     struct sockaddr *from, socklen_t *fromlen); 
		

#include <sys/socket.h>

#include <sys/stat.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>

int main(int argc, char **argv)
{
    int server_sockfd, client_sockfd;
    int client_len, n;
    char buf[80];
    struct sockaddr_in clientaddr, serveraddr;

    client_len = sizeof(clientaddr);

    if ((server_sockfd = socket (AF_INET, SOCK_STREAM, 0)) < 0)
    {
        perror("socket error : ");
        exit(0);
    }
    bzero(&serveraddr, sizeof(serveraddr));
    serveraddr.sin_family = AF_INET;
    serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
    serveraddr.sin_port = htons(atoi(argv[1]));

    bind (server_sockfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr));
    listen(server_sockfd, 5);

    while(1)
    {
        memset(buf, 0x00, 80);
        client_sockfd = accept(server_sockfd, (struct sockaddr *)&clientaddr,
                            &client_len);

        if ((n = recvfrom(client_sockfd, buf, 80, 0, NULL, &client_len)) <= 0)
        {
            close(client_sockfd);
            continue;
        }
        sendto(client_sockfd,(void *)buf, 80, 0,
                        NULL, client_len);
        close(client_sockfd);
    }
}