rcookie...

 Introduction To The Fortune Cookie Problem

Nearly everyone that I know enjoys reading the little messages that are enclosed in fortune cookies. Fortune cookies are so popular that the computer equivalent, the fortune program, has become a standard feature of nearly every variant of UNIX.

Most variants of UNIX have a small but entertaining fortune cookie database pre-installed. Additional fortune cookie files have been posted to USENET over the years, and a large collection is on-line at UUNET. As a result, a dedicated fortune cookie fan can accumulate a rather large amount of fortune cookie data. This can become a real problem when your site has a large number of UNIX machines. It is a time sink to have to update a lot of machines, and it also consumes a great deal of disk space to have a cookie database replicated on a number of different machines.

 A Solution To The Fortune Cookie Problem

The obvious solution to the fortune cookie problem is to have a centralized fortune cookie repository, and a tool that can access this cookie warehouse from across the network. The remainder of this document describes the implementation of just such a system.

 The Fortune Cookie Protocol

The cookie protocol is very simple—the client sends a single one character message to the server, and the server sends back a single message up to 64K in length. The cookie service runs from the Internet Super-daemon (inetd) on UDP port #17.

 The Fortune Cookie Server Program

/* *** ------------------------------------------------------------ *** */
/* *** File:	cookied.c					    *** */
/* *** ------------------------------------------------------------ *** */
/* *** Written by Bart Massey *** */
/* *** Bug fix by Chris McNeil *** */

#include <stdio.h>
#include <syslog.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define FORTUNEBUFSIZE  (64 * 1024)
char	fbp[ FORTUNEBUFSIZE ];

/* *** Change this definition to match your local system *** */
#define FORTUNEPROG     "/usr/games/fortune -a"

/* *** ------------------------------------------------------------ *** */
/* *** Main Procedure: respond to cookie requests from the network  *** */
/* *** ------------------------------------------------------------ *** */

main( argc, argv )
  int	argc;
  char	**argv;
{
  int	i;
  FILE	*pfile;
  int	fromlen;
  struct sockaddr_in from;

  fromlen = sizeof( from );

/* *** Read the one character request from the client *** */
/* *** Specific content is ignored *** */

  if ( recvfrom( 0, fbp, FORTUNEBUFSIZE, 0, (struct sockaddr *) &from,
	&fromlen ) == -1 )
  {
    exit( 1 );
  }

/* *** Connect with the local fortune cookie program *** */
/* *** via a pipe connection. *** */

  pfile = popen( FORTUNEPROG, "r" );

  if ( !pfile )
  {
        exit( 1 );
  }

/* *** Read the fortune from the pipe char by char and save in a buffer *** */

  for ( i = 0; FORTUNEBUFSIZE; )
  {
    fbp[i] = getc( pfile ); 

    if ( fbp[i] == EOF )
    {
      fbp[i] = '\0'; 
      break;
    }
    i++;
  }

  pclose( pfile );  

/* *** Send the cookie buffer back to the client in one shot *** */

  sendto( 0, fbp, i + 1, 0, &from, fromlen );

  exit( 0 );
}

/* *** ------------------------------------------------------------ *** */
/* *** End Of File:	cookied.c				    *** */
/* *** ------------------------------------------------------------ *** */

 The Fortune Cookie Client Program

/* *** ------------------------------------------------------------ *** */
/* *** File:	rcookie.c					    *** */
/* *** ------------------------------------------------------------ *** */
/* *** Written by John Weeks *** */
/* *** Based on UCB "rdate" command *** */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>      
#include <netdb.h>
#include <stdio.h>

#define FORTUNEBUFSIZE  (64 * 1024)
char buf[ FORTUNEBUFSIZE ];

/* *** Change this to be your local cookie server *** */
#define DEFAULTHOST "abc.yourhost.com"

/* *** ------------------------------------------------------------ *** */
/* *** Main Procedure: check args and locate host name		    *** */
/* *** ------------------------------------------------------------ *** */

main ( argc, argv )
  int	argc;
  char	*argv[];
{
  if ( argc == 1 ) 
    DoRemoteCookie( DEFAULTHOST );
  else
    DoRemoteCookie( argv[1] );
}

/* *** ------------------------------------------------------------ *** */
/* *** DoRemoteCookie: contact remote cookie server & get fortune *** */
/* *** ------------------------------------------------------------ *** */

int DoRemoteCookie( host )
  char	*host;
{
  struct	hostent		*hname;		/* /etc/hosts table entry */
  struct	servent		*sname;		/* /etc/service file entry */
  struct	sockaddr_in	socaddr;	/* socket address */
  int		soc;				/* network file descriptor */

/* *** Look up the host name in /etc/hosts or via DNS *** */

  if ( ( hname = gethostbyname( host ) ) == NULL )
  {
    fprintf( stderr, "rcookie: Unknown host %s\n", host );
    return( -1 );
  }

/* *** Look up the cookie service in /etc/services *** */

  if ( ( sname = getservbyname( "cookie", "udp" ) ) == NULL ) 
  {
    fprintf( stderr, "rcookie: cookie/udp: unknown service\n" );
    return( -1 );
  }

/* *** Open a network socket, type DGRAM since service is UDP *** */

  if ( ( soc = socket( AF_INET, SOCK_DGRAM, 0, 0 ) ) < 0 )
  {
    perror( "rcookie" );
    return( -1 );
  }

/* *** Set up network structures in preparation for connect call *** */

  socaddr.sin_family = hname->h_addrtype;      
  bcopy( hname->h_addr, (caddr_t) &socaddr.sin_addr, hname->h_length );
  socaddr.sin_port = sname->s_port;

/* *** Connect to the cookie daemon on remote host *** */

  if ( connect( soc, (caddr_t) &socaddr, sizeof( socaddr ), 0 ) < 0 )
  {
    perror( "cookie" );
    close( soc );
    return( -1 );
  }

/* *** Write anything to the cookie daemon to wake it up *** */

  if ( write( soc, "x", 1 ) != 1 )
  {
    perror( "rcookie" );
    close( soc );
    return( -1 );
  }

/* *** Read the returned fortune cookie into a buffer *** */

  if ( read( soc, &buf[ 0 ], FORTUNEBUFSIZE ) < 1 )
  {
    perror( "rcookie" );
    close( soc );
    return( -1);
  }

/* *** Send the fortune cookie in buffer out to screen *** */

  printf( "%s", buf );

/* *** Close socket before exiting, then return good completion code *** */

  close( soc );
  return( 0 );
}

/* *** ------------------------------------------------------------ *** */
/* *** End Of File:	rcookie.c				    *** */
/* *** ------------------------------------------------------------ *** */

 Building And Installing The Fortune Cookie System