//  File name : tcp.C
//     by Ee-Chien Chang
//---------------------------------------------------------
//          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>
#include </usr/include/stdlib.h>
#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 );
void out_usage();


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;
  for (int i = 0 ; flag < 0 && i < 5 ; i ++ )
     {
//       cout << "trying to establish connection " << endl;
       sd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
       if (sd < 0)
        {
         perror( "Open Socket failed:");
	 out_usage();
         exit(1);
        }

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

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

//  cout << "here...." << flag << endl;
  if (flag < 0 )
     {
        perror ("no connection:");
        close(sd);
	out_usage();
        exit(1);
     }

  return sd;
}

void out_usage()
{
	cerr << "Usage:" << endl << "\tclient [-p port_number] [server_name]"
	     << endl << endl << "\tserver_name :\t the name of the server"
	     << endl << "\t\t\t(default server: brutus.ams.sunysb.edu" << endl
	     << "\t\t\t defualt port number: 1222)" << endl;
}