/*
** Echo server; demonstrates internet sockets
*/

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <netdb.h>

int main(int argc, char *argv[])
{
  int s, s2, t, len, portno;
    struct sockaddr_in local, remote;
    char str[100];

    if(argc < 2){
      fprintf(stderr, "Format: <a.out> PORT_NUMBER\n");
      exit(1);
    }
    portno = atoi(argv[1]);

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

    bzero((char *)&local, sizeof(local));

    local.sin_family = AF_INET;
    local.sin_addr.s_addr = INADDR_ANY;
    local.sin_port = htons(portno);
    
    if (bind(s, (struct sockaddr *)&local, sizeof(local)) < 0) {
        perror("bind");
        exit(1);
    }

    if (listen(s, 5) == -1) {
        perror("listen");
        exit(1);
    }

    for(;;) {
        int done, n;
        printf("Waiting for a connection...\n");
        t = sizeof(remote);
        if ((s2 = accept(s, (struct sockaddr *)&remote, &t)) < 0) {
            perror("accept");
            exit(1);
        }

        printf("Connected.\n");

        done = 0;
        do {
            n = read(s2, str, 100);
            if (n <= 0) {
                if (n < 0) perror("recv");
                done = 1;
            }

            if (!done) 
                if (write(s2, str, n) < 0) {
                    perror("send");
                    done = 1;
                }
        } while (!done);

        close(s2);
    }

    return 0;
}