#!/usr/bin/perl

######################################################################
#                                                                    #
# (c) Anthony G. Basile, June 3, 2002                                #
#                                                                    #
# Server proxy.                                                      #
#                                                                    #
######################################################################

#
# Get the arguments.
#

$lhost = $ARGV[0] ;
$lport = $ARGV[1] ;
$rport = $ARGV[2] ;

#
# Subroutines
#

sub logit {
   my $msg = $_[0] ;
   my $date = `date` ;
   chomp($date) ;
   print LOG $date . ' : ' . $msg . "\n" ;
}

#
# Packages
#

use Socket ;
use POSIX ;

#
# Signal trapping --- clean up zombies
#

$SIG{CHLD} = 'IGNORE' ;

#
# Prepare a socket listening for incoming connections.
#

$proto  = getprotobyname('tcp') ;

$raddr    = sockaddr_in( $rport, INADDR_ANY ) ;

socket    ( SOCK, PF_INET, SOCK_STREAM, $proto ) ;
setsockopt( SOCK, SOL_SOCKET, SO_REUSEADDR, 1 )  ;
bind      ( SOCK, $raddr )                       ;
listen    ( SOCK, SOMAXCONN )                    ;

LOOP:
accept    ( RSOCK, SOCK )   ;
goto LOOP if $pid=fork()    ;


#
# We got a connection so we don't need to listen anymore.
# Begin appending to the log.
# Report who just connected as a remote host.
#

close( SOCK ) ;

$log = "$lhost." . "$lport." . "$rport." . 'log' ;
open( LOG, '>>' . $log ) ;

$peer = getpeername( RSOCK ) ;
($pport,$paddr) = unpack_sockaddr_in($peer) ;
$pip = inet_ntoa( $paddr ) ;

logit("Connected: $pip:$pport") ;


#
# Prepare a socket and connect to service on $lhost:$lport
#

$lserver = gethostbyname($lhost) ;
$laddr   = sockaddr_in( $lport, $lserver ) ;

socket ( LSOCK, PF_INET, SOCK_STREAM, $proto ) ;
connect( LSOCK, $laddr )                       ;


#
# Check when LSOCK and RSOCK are ready to read/write.
#

$rin = "" ;
vec($rin, fileno(LSOCK), 1) = 1 ;
vec($rin, fileno(RSOCK), 1) = 1 ;

while (1) {

   select $ready = $rin, undef, undef, undef ;

   if (vec($ready, fileno(LSOCK), 1) == 1) {
      $bytes = sysread  (LSOCK, $msg, 256 ) ;
      goto EXIT unless $bytes ;
      syswrite (RSOCK, $msg, length($msg) ) ;
   }

   if (vec($ready, fileno(RSOCK), 1) == 1) {
      $bytes = sysread  (RSOCK, $msg, 256 ) ;
      goto EXIT unless $bytes ;
      syswrite (LSOCK, $msg, length($msg) ) ;
   }

}

EXIT:
logit('***') ;
close(LOG) ;
close(RSOCK) ;
close(LSOCK) ;