server.c

/* server code of a half duplex chat program        */


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

#define MYPORT      4950

#define MAXBUFLEN   100

int main(void)
{
        int sockfd;
        struct sockaddr_in my_addr;
        struct sockaddr_in their_addr;
        int addr_len, numbytes;
        char buf[MAXBUFLEN];
        char arr[MAXBUFLEN];

        if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1)    {
                perror("socket");
                exit(1);
        }

        my_addr.sin_family = AF_INET;
        my_addr.sin_port = htons(MYPORT);
        my_addr.sin_addr.s_addr = INADDR_ANY;
        memset(&(my_addr.sin_zero), '\0', 8);

        if (bind(sockfd, (struct sockaddr *)&my_addr,
                                sizeof(struct sockaddr)) == -1) {
                perror("bind");
                exit(1);
        }

        addr_len = sizeof(struct sockaddr);

        while(1) {
             if ((numbytes = recvfrom(sockfd, buf, MAXBUFLEN-1, 0,
                                        (struct sockaddr *)&their_addr, &addr_len)) == -1) {
                        perror("recvfrom");
                        exit(1);
                }

                buf[numbytes] = '\0';
                printf("got packet from %s\n", inet_ntoa(their_addr.sin_addr));
                printf("%s\n", buf);
                printf("Type the message:\n");
                gets(arr);
                if ((numbytes = sendto(sockfd, arr, strlen(arr), 0, (struct sockadd *)&their_addr, sizeof(struct sockaddr))) == -1) {
                        perror("send to client");
                        exit(1);
                }
        }

        close(sockfd);

        return 0;
}