#include <stdlib.h>
#include <stdio.h>             /* Basic I/O routines          */
#include <sys/types.h>        /* standard system types       */
#include <netinet/in.h>      /* Internet address structures */
#include <sys/socket.h>     /* socket interface functions  */
#include <netdb.h>         /* host to IP resolution       */
#include <unistd.h>


#define portno  6789             /*  default port of host  */


void error(char *msg);
int main(int argc, char *argv[]);

void error(char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
     int serversocket;
     int newsockfd;
     int clilen;  
     char buffer[4096];
     struct sockaddr_in serv_addr, cli_addr;
    
     /*portno = 80;*/
    
     int n;
    
     
   serversocket = socket(AF_INET, SOCK_STREAM, 0);

    if (serversocket < 0)
       {
        error("ERROR opening socket");
       }
       
       
       

         
         bzero((char *) &serv_addr, sizeof(serv_addr));
        serv_addr.sin_family = AF_INET;
        serv_addr.sin_addr.s_addr = INADDR_ANY;
        /*portno=atoi(argv[1]);*/
         serv_addr.sin_port = htons(portno);
         printf("Socket has port #%d\n", serv_addr.sin_port);
          
   
    
     if (bind(serversocket, (struct sockaddr *) &serv_addr,
              sizeof(serv_addr)) < 0)
              {
              error("ERROR on binding");
              }
             
             
             
     listen(serversocket,5);
    
   
    
     while (1) {
       
         clilen = sizeof(cli_addr);
       
     newsockfd = accept(serversocket,(struct sockaddr *) &cli_addr, &clilen);
                
     if (newsockfd < 0)
          {
          error("ERROR on accept");
          }
    
    
     n = write(newsockfd, buffer, sizeof(buffer)-1);
    
     if (n < 0)
         {
          error("ERROR writing to socket");
          }
          close(newsockfd);
          }
     return 0;
}