non-blocking tcp/ip Chat Server

/*
   Basic non-blocking TCP/IP Chat Server Source Code


 * Copyright (c) 2014 JUAN JOSE FERNANDEZ LOPEZ
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.


   Contact: Current Cel & email - 7873973266 - jjfl.88@aol.com


   Example client: $ nc serverhosturlorip 6660 [enter]
                   INPUT: myname [enter]
                   INPUT: THE MESSAGE [enter]
                   OUTPUT: myname> THE MESSAGE

*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <poll.h>
#include <signal.h>
#include <time.h>
#include <fcntl.h>
#include <netdb.h>
#define PORT 6660

struct pollfd *fds;

/* used to record client information */

typedef struct {
  int fd;
  char name[260];
  _Bool nameset:1;
} client;

client *clnt;

/* set-up ipv4 address */

void setipv4address(struct sockaddr_in * serv_addr)
{
   serv_addr[0].sin_family = AF_INET;
   serv_addr[0].sin_addr.s_addr = INADDR_ANY;
   serv_addr[0].sin_port = htons((uint16_t)PORT);
}

/* signal handling */

void terminate(int n) {
   free(fds);
   free(clnt);
   exit(n);
}

int main(void)
{
   /* BSD DAEMON */
   void daemonize();

   void setipv4address(struct sockaddr_in *);
   void terminate(int);
   int sockfd,i,read_val,msglen,seconds;
   int tcp_protocol_number = (getprotobyname("tcp"))->p_proto;
   char buff[256];
   char msg[500];
   nfds_t nfds,x;
   int on;
   socklen_t cli_addr_len;
   struct sockaddr_in serv_addr, cli_addr;

   daemonize();
   cli_addr_len = sizeof(cli_addr);
   sockfd = socket(AF_INET, SOCK_STREAM, 0);
   seconds=25;
   on=1;
   signal(SIGINT,terminate);
   signal(SIGTERM,terminate);
   signal(SIGPIPE,SIG_IGN);
   setipv4address(&serv_addr);
   if((bind(sockfd, (struct sockaddr *) &serv_addr,sizeof(serv_addr))) == -1)
   {
      exit(EXIT_FAILURE);
   }
   if((listen(sockfd,5)) == -1) {
      exit(EXIT_FAILURE);
   }
   nfds = 1;
   if(!(clnt = (client *) calloc (1,nfds * sizeof(client))))
   {
     perror("ERROR: ");
     exit(EXIT_FAILURE);
   }
   if(!(fds = (struct pollfd *) calloc(1,nfds * sizeof(struct pollfd))))
   {
     perror("ERROR: ");
     exit(EXIT_FAILURE);
   }

   fds[0].fd = sockfd;
   fds[0].events = POLLIN;
   clnt[0].fd = sockfd;
   clnt[0].name[0]='\0';

   while(1) {
      poll(fds,nfds,-1);
      for(i=0; (i < (int) nfds); ++i)
      {

         if( !i  && (fds[i].revents & POLLIN)  ) {

            clnt = (client *)        realloc(clnt,((nfds+1) * sizeof(client)));
            fds =  (struct pollfd *) realloc(fds, ((nfds+1) * sizeof(struct pollfd)));

            if((fds[nfds].fd = accept(sockfd,(struct sockaddr *) &cli_addr, &cli_addr_len)) != -1)
            {

                if( (fcntl(fds[nfds].fd,F_SETFL,O_NONBLOCK)) == -1) {
                     perror("fcntl() = -1: ");
                }

#ifdef TCP_KEEPIDLE
                if((setsockopt(fds[nfds].fd,tcp_protocol_number,TCP_KEEPIDLE,&seconds,sizeof(seconds))) == -1) {
                     perror("setsockopt() == -1 1: ");
                }
#endif

                if((setsockopt(fds[nfds].fd,SOL_SOCKET,SO_KEEPALIVE,&on,sizeof(on))) == -1) {
                     perror("setsockopt() == -1 2: ");
                }

                fds[nfds].events = POLLRDNORM;
                clnt[nfds].nameset = 0;
                clnt[nfds].fd = fds[nfds].fd;

            }

            else
            {
               free(fds);
               free(clnt);
               perror("ERROR> -1 on accept(): ");
               exit(EXIT_FAILURE);
            }

            ++nfds;
         }


         else if( fds[i].revents & (POLLNVAL | POLLHUP | POLLERR) ) {
            if(!(fds[i].events & POLLNVAL)) {
               close(fds[i].fd);
            }
            --nfds;
               if((nfds - i) == 0) {
                 x=1;
               }
               else {
                 x=nfds-1;
               }
            memcpy((&(clnt[i])), (&(clnt[i+1])),sizeof(clnt) * (x));
            memcpy( (&(fds[i])), (&(fds[i+1])),sizeof(struct pollfd) * (x));
            fds = (struct pollfd *) realloc( fds, ( nfds * (sizeof(struct pollfd)) ) );
            clnt = (client *) realloc( clnt, ( nfds * (sizeof(client)) ) );
         }

         else if( (i != 0) && (fds[i].revents & POLLRDNORM) ) {
            read_val = read(fds[i].fd,buff,255);
            buff[read_val] = '\0';

            if(read_val <= 0) {
               if(!(read_val)) {
                  close(fds[i].fd);
               }
               --nfds;
               if((nfds - i) == 0) {
                 x=1;
               }
               else {
                 x=nfds-1;
               }
               memcpy( (&(clnt[i])), (&(clnt[i+1])),sizeof(client) * (x));
               memcpy( (&(fds[i])), (&(fds[i+1])), sizeof(struct pollfd) * (x));
               fds = (struct pollfd *) realloc( fds, ( nfds * (sizeof(struct pollfd)) ) );
               clnt = (client *) realloc( clnt, ( nfds * (sizeof(client)) ) );
            }

            else {
               if((clnt[i].nameset)) {
                 x=1;
                 msg[0]='\0';
                 strcat(msg,clnt[i].name);
                 strcat(msg,"> ");
                 strcat(msg,buff);
                 msglen=strlen(msg);
                 while(x < nfds)
                 {
                    write(clnt[x].fd,msg,msglen);
                    ++x;
                 }
               }

               else {
                  clnt[i].nameset = 1;
                  clnt[i].name[0] = '\0';
                  if(buff[(strlen(buff))-1] == '\n') {
                    buff[(strlen(buff))-1] = '\0';
                  }
                  strcat(clnt[i].name,buff);
               }
            }

         }

      }
   }

   /*
      Flow never reach here
   */
   free(fds);
   free(clnt);
   return 0;
}

void daemonize()
{
     pid_t pid;                           /* PROCESS ID                                                  */
     pid_t sid;                           /* SESSION ID (SAME AS PID)                                    */
     pid = fork();                        /* NEW CHILD                                                   */
     if (pid < 0)                         /* ERROR HANDLING                                              */
        exit(EXIT_FAILURE);
     if (pid > 0)
        exit(EXIT_SUCCESS);               /* SAY BYEBYE TO FATHER                                        */
     umask(0);                            /* TO BE SURE WE HAVE ACCESS TO ANY GENERATED FILE FROM DAEMON */
     sid = setsid();                      /* WE OWN OUR OWN PLACE                                        */
     if (sid < 0)                         /* ERROR HANDLING                                              */
        exit(EXIT_FAILURE);
     if((chdir("/")) < 0)                /* CHANGE TO A PATH THAT WILL ALWAYS BE THERE                  */
        exit(EXIT_FAILURE);
     close(STDIN_FILENO);                 /* CLOSE STANDARD INPUT                                        */
     close(STDOUT_FILENO);                /* CLOSE STANDARD OUTPUT                                       */
     close(STDERR_FILENO);                /* CLOSE STANDARD ERROR OUTPUT                                 */
}