/*Andrea James
  CS35010 Assignment
  26 March 1998
  drinks client
  
  All socket code based on lecture notes  */

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/utsname.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

/*A function to create a client socket that can connect to
 *a server*/
int call_socket (char *host, int port);

/*Converts characters representing a 4-digit number into an
 *equivalent integer. Used for interpreting messages from the
 *server*/
int ConvertCharToInt (char *the_string);

void main ()
{
int s;    /*variable for socket*/
int port; /*holds port number*/
struct servent *the_servent;
char user[5], servername[20];
char buffer[40];
int x, size;

/*get port number of created service (aaj8) */
the_servent = getservbyname ("aaj8", "tcp");
if ( the_servent == NULL )
   {printf ("Error getting port number.\n");
   exit (1);}
port = the_servent->s_port;
printf ("Port number is %d.\n", port);

/*request for a server name*/
printf ("Please enter a server name: ");
scanf ("%s", servername);

/*pass & retrieve information over connection*/
printf ("Control-C to exit.\n\n");

/*infinite loop*/
while (1)
   {
/*prompt user for a message to pass to server*/
   printf ("prompt>");
   scanf ("%s", user);
   
/*use call_socket function to connect to specified server*/
if ( (s=call_socket (servername, port)) < 0 )
   {perror("Call Failed.");
   exit(1);}
   printf ("Data socket is %d\n", s);   
 
/*write message to server*/
   x=write (s, user, 5);

/*read response*/
   x=read (s, buffer, 4);
   size=ConvertCharToInt(buffer);
   x=read (s, buffer, size);

/*output response to the screen*/
   buffer[size-1]='\0';
   printf ("\nServer reply:\n%s\n", buffer);

/*close connection*/
   close(s);
   }
}

int call_socket (char *host, int port)
{
struct sockaddr_in sa;
struct hostent *hp;
int s;

if ( (hp=gethostbyname(host)) == NULL )
  {errno=ECONNREFUSED;
   return (-1);}

memset ( &sa, 0, sizeof(sa) );

memcpy( (char*)&sa.sin_addr, hp->h_addr, hp->h_length );

sa.sin_family = hp->h_addrtype;

sa.sin_port = htons( (u_short)port );

if ( (s = socket(hp->h_addrtype, SOCK_STREAM, 0)) < 0 )
   return (-1);

if ( connect(s, (struct sockaddr*)&sa, sizeof(sa)) < 0 )
   return (-1);

return (s);
}

int ConvertCharToInt (char *the_string)
{
int temp=0;

temp = ( ((int)the_string[0]) - 48)*1000;
temp += ( ((int)the_string[1]) - 48)*100;
temp += ( ((int)the_string[2]) - 48)*10;
temp += ( ((int)the_string[3]) - 48);

return temp;
}