Simple-Chat (Echo Server)

/*
 * Copyright (C) 2011 - Simple-Chat (Echo Server) 0.1 (Under Construction)
 * developed by Raphael S.Carvalho (a.k.a Utroz)
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.  You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 */

// File: Server.c
/* A simple server in the internet domain using TCP
   The port number is passed as an argument */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

void dostuff (int , const short);
void error(const char *);

int main(int argc, char *argv[])
{
        static short user_id = 0;
        int sockfd, newsockfd, portno, pid;
        struct sockaddr_in serv_addr, cli_addr;
        socklen_t clilen;

        if (argc < 2) {
        fprintf(stderr,"ERROR, no port provided\n");
        exit(EXIT_FAILURE);
        }

        fprintf(stdout, "%s (v.%.2f) by %s", ":: Simple-Chat", 0.1, "by Utroz ::\n");
        fprintf(stdout, "\nStarting server...");

        sockfd = socket(AF_INET, SOCK_STREAM, 0);
        if (sockfd < 0)
        error("ERROR opening socket");

        bzero((char *) &serv_addr, sizeof(serv_addr));
        portno = atoi(argv[1]);

        serv_addr.sin_family = AF_INET;
        serv_addr.sin_addr.s_addr = INADDR_ANY;
        serv_addr.sin_port = htons(portno);

        if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
        error("ERROR on binding");

        listen(sockfd,5);
        clilen = sizeof(cli_addr);

        fprintf(stdout, " (Ready).\n- Waiting to connections...\n\n");

        while (1) {
        newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
        if (newsockfd < 0)
                error("ERROR on accept");
        else
                fprintf(stdout, "User id: %1d was connected!\n", ++user_id);

        pid = fork();
        if (pid < 0) {
                close(newsockfd);
                error("ERROR on fork");
        } else if (pid == 0) {
                close(sockfd);
                dostuff(newsockfd, user_id);
        }
        }

        close(newsockfd);
        close(sockfd);
        return EXIT_SUCCESS;
}

void dostuff (int sock, const short id)
{
        int n;
        char buffer[256];

        while (1) {
        bzero(buffer, 256);

        n = read(sock, buffer, 255);
        if (n < 0)
                error("ERROR reading from socket");

        if (strncmp("$kill", buffer, 5) == 0) {
                fprintf(stdout, "User id: %1d was disconnected!\n", id);
                n = write(sock, "log", 4);
                close(sock);
                exit(EXIT_SUCCESS);
        } else if (buffer[0] == 0)  {
                close(sock);
                error("ERROR reading from buffer");
        }

        fprintf(stdout, "Message received: %s\n",buffer);
        n = write(sock, buffer, n);
        if (n < 0)
                error("ERROR writing to socket");
        }
}

void error(const char *msg)
{
        perror(msg);
        exit(EXIT_FAILURE);
}

/*---------------- */
// File: Client.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

void error(const char *msg)
{
        perror(msg);
        exit(0);
}

int main(int argc, char *argv[])
{
        int sockfd, portno, n;
        struct sockaddr_in serv_addr;
        struct hostent *server;
        char buffer[256];

        if (argc < 3) {
        fprintf(stderr,"usage %s hostname port\n", argv[0]);
        exit(0);
        }

        printf("%s (v.%.2f) by %s", ":: Simple-Chat", 0.1, "by Utroz ::\n");

        portno = atoi(argv[2]);

        sockfd = socket(AF_INET, SOCK_STREAM, 0);
        if (sockfd < 0)
        error("ERROR opening socket");

        server = gethostbyname(argv[1]);
        if (server == NULL) {
        fprintf(stderr,"ERROR, no such host\n");
        exit(0);
        }

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

        serv_addr.sin_family = AF_INET;

        bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length);
        serv_addr.sin_port = htons(portno);

        if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
        error("ERROR connecting");

        while(1) {
        printf("Please enter the message: ");
        bzero(buffer,256);
        fgets(buffer,255,stdin);

        n = write(sockfd,buffer,strlen(buffer));
        if (n < 0)
                error("ERROR writing to socket");
        //bzero(buffer,256);

        n = read(sockfd, buffer, 255);
        if (strncmp("log", buffer, 3) == 0) {
                printf("Alert: You was disconnected!\n");
                close(sockfd);
                exit(0);
        }
        if (n < 0)
                error("ERROR reading from socket");

        printf("Message received: %s\n",buffer);
        }

        close(sockfd);
        return 0;
}