//---------------------------------------------------------
//          T C P       routines
//---------------------------------------------------------
//     Open a socket  for the client and 
//     return a stream for the client
//---------------------------------------------------------
//   usage
//        FILE *fp;
//        int  sd =  establishconnection 
//                          (  "granny.cs.nyu.edu", 1222,
//                              &(fp) )
//                      .....
//                    close (fp );
//                    close (sd );
//----------------------------------------------------------
//
//
//----------------------------------------------------------

#include <iostream.h>
#include <stdio.h>
#ifdef SUN
   #include <stdlib.h>
#endif

#include <string.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <unistd.h>           /* read(), write(), close() */


#define SIZE     256     /* max length of a string */
#define MAXLINES 40      /* number of screen lines printed */
#define CR       13
#define LF       10


int open_socket(char *host, char *cmd, int port_number );


int establish_connection ( char *host, int port_number ,
                           FILE **fp )
{
   int sd = -1;
   sd = open_socket ( host, host, port_number );

   fp[0] =  fdopen(sd,"r");

   return (sd);
}

int open_socket(char *host, char *cmd, int port_number )

/* Create a socket. Assign host's details to name.
   Create a stream using name and connect the socket
   to it.
*/

{

  struct sockaddr_in name;
  struct hostent *hptr;
  int sd;


  int flag = -1;
  while (flag < 0 )
     {
       cout << "trying to establish connection " << endl;
       sd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
       if (sd < 0)
        {
         perror( "Open Socket failed:");
         exit(1);
        }

       name.sin_family = PF_INET;
       name.sin_port = htons(port_number);         /* 80 for  HTTP server */

       if ((hptr = gethostbyname(host)) == NULL) {
         perror("gethostbyname");
         exit(1);
       }

       /* copy the IP address of host into name */

       printf ( " name of host %s lenght %d\n",hptr->h_name, hptr->h_length);
       bcopy(hptr->h_addr, &name.sin_addr.s_addr, hptr->h_length);

       printf("Trying to contact %s...\n", host);
     
       flag = connect(sd, (sockaddr *)&name, sizeof(name)) ;
       if (flag<0)
          { 
            sleep(1);
            cout << "try again" << endl;
          }
     }

  char alive = 1;
  setsockopt(sd, IPPROTO_TCP, SO_KEEPALIVE,
                       &alive, (int) sizeof(alive));

  cout << "here...." << flag << endl;
  if (flag >= 0 )
     {
        cout << "success" << endl;
     }
  else
     {
        perror ("no connection:");
        close(sd);
        perror("connection failed:");
        exit(1);
     }

  return sd;
}