/***************************************************************************

   tcp_client    Designed as a simple class example.  The program waits for
              a request.  It assumes that request is numerical.  It adds
              +1 to the input and sends it back.

   This program expects one argument:
   tcp_client <hostname> 
   The argument says where the server is

   Version 1.0   October, 2002 Yvan Petillot
****************************************************************************/
#include       <stdio.h>
#include       <stdlib.h>
#include       <sys/socket.h>
#include       <netinet/in.h>
#include       <netdb.h>
#include       <sys/socket.h>
#include       <fcntl.h>
#include       <netinet/in.h>
#include       <unistd.h>

#define         TRUE            1
#define         FALSE           0
#define         BUFFER_SIZE     100
#define         PORT            10000

void    SysError( char * );

/* Main Program */
main ( int argc, char *argv[] )
{
  long               input_value;
  int                family = AF_INET;       /* The default for most cases */
  int                type   = SOCK_STREAM;   /* Says it's a TCP connection */
  in_port_t          port   = PORT;         /* Use a free port to establish connection */
  int                result;
  struct sockaddr_in client;      /* Structure storing socket info for client */
  struct sockaddr_in server;      /* Structure storing socket info for server */
  int                lclient = sizeof(client);
  int                fd;   /* Socket id. On Unix a socket is a file descriptor */
  char               console_buffer[BUFFER_SIZE];  
  char               ip_input_buffer[BUFFER_SIZE];
  char               ip_output_buffer[BUFFER_SIZE];
  struct hostent     *host;

  
  /* Checks first we have the correct number of arguments */
  if ( argc < 2 ) {
    printf( "The program expects arguments\n" );
    printf( "tcp_client <hostname>\n" );
    exit(0);
  }
  if ((host = gethostbyname(argv[1])) == (struct hostent *)NULL) 
    {
      SysError("Error on gethostbyname");
      return(-1);
    }
  /* Create socket*/
  if ((fd = socket (family, type, 0)) < 0)
    {
      SysError ("Error on socket");
    }
  /* Fills client socket structure with correct fields */
  client.sin_family       = family;
  client.sin_port         = port;              /* client & server see same port*/
  client.sin_addr.s_addr  = htonl(INADDR_ANY); /* the kernel assigns the IP addr*/
  /* Fills server socket structure with correct fields */
  server.sin_family       = family;
  server.sin_port         = port;              /* client & server see same port*/
  memcpy((char *)&server.sin_addr, (char *)host->h_addr, host->h_length);
  
  /* We are a client here */
 
  /* Go directly to connect. You must have a server running*/
  if (connect(fd, (struct sockaddr *)&server, sizeof(server) ))
    SysError ("Error on connect");
  /* Until fault */
  while( TRUE )
    {
      /* Get a number from console */
      printf( "> " );
      bzero( console_buffer, sizeof(console_buffer ));
      scanf( "%s", console_buffer );
      /* Convert it to integer (-1 to exit)*/
      if ( atoi( console_buffer ) == -1 )
	{
	  printf( "We Have Successfully Finished.\n" );
	  exit(0);
	}
      /* Make sure output buffer is empty */
      bzero( ip_output_buffer, sizeof( ip_output_buffer ));
      /* Copy value to output buffer */
      strcpy( ip_output_buffer, console_buffer );
      /* Send value to server */
      if ( send( fd, ip_output_buffer, 
		 strlen(ip_output_buffer) + 1, 0 ) <= 0 )
	SysError( "Error on send" );
      /* Make sure input buffer is empty*/
      bzero( ip_input_buffer, sizeof(ip_input_buffer) );
      /* receive data back from server */
      if ( recv( fd, ip_input_buffer, 
		 sizeof(ip_input_buffer) - 2, 0 ) <= 0 )
	SysError( "Error on recv" );
      /*Print reception */
      printf( "%s\n", ip_input_buffer );
    }                               /* End of while TRUE    */
}                                   /* End of client case   */
/* End of main          */



void    SysError( char *string )
{
  printf( "Error found:  String given is --> %s\n", string );
  exit(0);
}