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

   udpTalk      Designed as a simple class example.  The program send a request                and waits for reply.

   This program expects one argument:
   udpTalk <hostname>
   Hostname identifies the listener
   
   Version 1.0   October, 2002 Yvan Petillot
****************************************************************************/

#include       <sys/types.h>
#include       <fcntl.h>
#include       <netdb.h>
#include       <sys/socket.h>
#include       <netinet/in.h>
#include       <unistd.h>
#include       <string.h>
#include       <errno.h>
#include       <stdio.h>
#include       <stdlib.h>

#define         TRUE            1
#define         FALSE           0
#define         BUFFER_SIZE     100
#define         PORT1           10001
#define         PORT2           10001

void    SysError( char * );

/* Main Program */
main ( int argc, char *argv[] )
{
  int                count;
  long               input_value;
  int                family = AF_INET;       /* The default for most cases */
  int                type   = SOCK_DGRAM;    /* Says it's a UDP connection */
  int                result;
  struct sockaddr_in my_addr;               /* Structure storing socket info */
  struct sockaddr_in their_addr;            /* Structure storing socket info */
  int                lsa = sizeof(my_addr);
  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;
  int                on;
  
  /* Checks first we have the correct number of arguments */
  if ( argc < 2 ) {
    printf( "The program expects arguments\n" );
    printf( "udpTalk <machine_name>\n" );
    exit(0);
  }

  host = gethostbyname(argv[1]);
  /* Create socket*/
  if ((fd = socket (family, type, 0)) < 0)
    {
      SysError ("Error on socket");
    }
  /* Fills my_addr socket structure with correct fields */
  my_addr.sin_family       = family;
  my_addr.sin_port         = PORT2;             
  my_addr.sin_addr.s_addr  = htonl(INADDR_ANY); /* the kernel assigns the IP addr*/
  
   /* Fills their socket structure with correct fields */
  their_addr.sin_family       = family;
  their_addr.sin_port         = PORT1;             

  memcpy((char *)&their_addr.sin_addr, (char *)host->h_addr, host->h_length);

  on = 1;
  setsockopt(fd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on));
  setsockopt(fd,SOL_SOCKET,SO_BROADCAST,&on,sizeof(on));

  /* First bind fd and sa structure*/ 
  /*if (bind (fd, (struct sockaddr *)&my_addr, sizeof(my_addr) ) == -1)
    SysError ("Error on bind");*/
  
  /* Infinite loop until fault */
  while( TRUE )
    {
      /* Get a number from console */
      printf( "> " );
      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 other machine */
      count = sendto(fd, ip_output_buffer, strlen(ip_output_buffer), 0,&their_addr,sizeof(their_addr) );
      if (count == 0)
	SysError( "Error on send" );
      /* Make sure input buffer is empty*/
      bzero( ip_input_buffer, sizeof(ip_input_buffer) );
      /* receive data back from machine */
      /*count = recvfrom( fd, ip_input_buffer,sizeof(ip_input_buffer),0,&their_addr,sizeof(their_addr));
      if (count == 0)
      SysError( "Error on recv" );*/
      /*Print reception */
      printf( "%s\n", ip_input_buffer );
    }  
  close(fd);
/* End of while TRUE    */
}                                 
/* End of main          */



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