#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
 
 
#define MAXCONNECT 5
 
static void
initaddr (struct sockaddr_in *servadrr,char *address,int port)
{ 
int adrsize = 0;
    if(address){
        adrsize = strlen(address);
        if(adrsize < 7 || adrsize > 15)
            exit(1);
        servadrr->sin_addr.s_addr = inet_addr(address);
    } else {
        servadrr->sin_addr.s_addr = INADDR_ANY;
    }
        
    servadrr->sin_family = AF_INET;
  servadrr->sin_port = htons (port);
   memset (&(servadrr->sin_zero), '\0', 8);
    
}
 
int
open_sock (int port)
{
 struct sockaddr_in servadr;
 int server_handle;
 int O_on = 1;
/* Create a new socket */
 if ((server_handle = socket (AF_INET, SOCK_STREAM, 0)) == -1)
    exit(1);
 if (setsockopt (server_handle, SOL_SOCKET, SO_REUSEADDR,
         &O_on, sizeof (int)) == -1)
    exit(1);
/* Now set the server address struct and bind socket to the port*/
 initaddr (&servadr,NULL, port);
 if (bind 
      (server_handle, (struct sockaddr *) &servadr,
       sizeof (struct sockaddr)) == -1)
    exit(1);
/* Listen on the socket */
 if (listen (server_handle, MAXCONNECT) == -1)
    exit(1);
 return server_handle;
}
void
close_sock (int sockhandle)
{
 close (sockhandle);
}