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    1: # The LearningOnline Network
    2: # URL translation for encrypted filenames
    3: #
    4: # $Id: lonenc.pm,v 1.2 2004/03/31 05:29:23 www Exp $
    5: #
    6: # Copyright Michigan State University Board of Trustees
    7: #
    8: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
    9: #
   10: # LON-CAPA is free software; you can redistribute it and/or modify
   11: # it under the terms of the GNU General Public License as published by
   12: # the Free Software Foundation; either version 2 of the License, or
   13: # (at your option) any later version.
   14: #
   15: # LON-CAPA is distributed in the hope that it will be useful,
   16: # but WITHOUT ANY WARRANTY; without even the implied warranty of
   17: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   18: # GNU General Public License for more details.
   19: #
   20: # You should have received a copy of the GNU General Public License
   21: # along with LON-CAPA; if not, write to the Free Software
   22: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   23: #
   24: # /home/httpd/html/adm/gpl.txt
   25: #
   26: # http://www.lon-capa.org/
   27: #
   28: 
   29: package Apache::lonenc;
   30: 
   31: use strict;
   32: use Apache::Constants qw(:common :remotehost);
   33: use Apache::lonnet();
   34: use Apache::File();
   35: use Apache::loncommon;
   36: use Crypt::IDEA;
   37: 
   38: sub handler {
   39:     my $r = shift;
   40:     my %cookies=CGI::Cookie->parse($r->header_in('Cookie'));
   41:     my $lonid=$cookies{'lonID'};
   42:     my $cookie;
   43:     if ($lonid) {
   44: 	my $handle=$lonid->value;
   45:         $handle=~s/\W//g;
   46:         my $lonidsdir=$r->dir_config('lonIDsDir');
   47:         if ((-e "$lonidsdir/$handle.id") && ($handle ne '')) {
   48: # Initialize Environment
   49:             &Apache::lonnet::transfer_profile_to_env($lonidsdir,$handle);
   50: # Decrypt URL and redirect
   51: 	    $r->internal_redirect(&unencrypted($r->uri));
   52: 	    return OK;
   53: 	} 
   54:     }
   55:     return FORBIDDEN;
   56: }
   57: 
   58: sub encryptseed {
   59:     my $seed=$ENV{'course.'.$ENV{'request.course.id'}.'.internal.encseed'};
   60:     $seed=~s/[^0-9a-f]/0/g;
   61:     $seed.='0123456789abcdef';
   62:     $seed=substr($seed.$seed,0,32);
   63:     return pack("H32",$seed);
   64: }
   65: 
   66: sub unencrypted {
   67:     my $uri=shift;
   68:     $uri=~s/^\/enc\/(\d+)\///;
   69:     my $cmdlength=$1;
   70:     my $seed=&encryptseed();
   71:     unless ($seed) {
   72: 	return '/'.$uri;
   73:     }
   74:     $uri=&Apache::lonnet::unescape($uri);
   75:     my $cipher=new IDEA $seed;
   76:     my $decuri='';
   77:     for (my $encidx=0;$encidx<length($uri);$encidx+=16) {
   78: 	$decuri.=$cipher->decrypt(
   79: 				  pack("H16",substr($uri,$encidx,16))
   80: 				  );
   81:     }
   82:     return substr($decuri,0,$cmdlength);
   83: }
   84: 
   85: sub encrypted {
   86:     my $uri=shift;
   87:     my $seed=&encryptseed();
   88:     unless ($seed) {
   89: 	return $uri;
   90:     }
   91:     my $cmdlength=length($uri);
   92:     $uri.='00000000';
   93:     my $encuri='';
   94:     my $cipher=new IDEA $seed;
   95:     for (my $encidx=0;$encidx<=$cmdlength;$encidx+=8) {
   96: 	$encuri.=unpack("H16",
   97: 			$cipher->encrypt(substr($uri,$encidx,8)));
   98:     }
   99:     return '/enc/'.$cmdlength.'/'.&Apache::lonnet::escape($encuri);
  100: }
  101: 
  102: 1;
  103: __END__
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