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- moving handler out of lonenc so it can be used in CGI

    1: # The LearningOnline Network
    2: # URL translation for encrypted filenames
    3: #
    4: # $Id: lonenc.pm,v 1.14 2006/04/07 22:15:34 albertel 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::lonnet;
   33: use Crypt::IDEA;
   34: use Time::HiRes qw(gettimeofday);
   35: 
   36: sub encryptseed {
   37:     my $seed=$env{'course.'.$env{'request.course.id'}.'.internal.encseed'};
   38:     $seed=~s/[^0-9a-f]/0/g;
   39:     $seed.='0123456789abcdef';
   40:     $seed=substr($seed.$seed,0,32);
   41:     return pack("H32",$seed);
   42: }
   43: 
   44: sub unencrypted {
   45:     my $uri=shift;
   46:     $uri=~s/^\/enc\/(\d+)\///;
   47:     my $cmdlength=$1;
   48:     my $seed=&encryptseed();
   49:     unless ($seed) {
   50: 	return '/'.$uri;
   51:     }
   52:     $uri=&Apache::lonnet::unescape($uri);
   53:     my $cipher=new IDEA $seed;
   54:     my $decuri='';
   55:     for (my $encidx=0;$encidx<length($uri);$encidx+=16) {
   56: 	$decuri.=$cipher->decrypt(
   57: 				  pack("H16",substr($uri,$encidx,16))
   58: 				  );
   59:     }
   60:     $env{'request.enc'}=1;
   61:     $decuri=&remove_noise($decuri);
   62:     return substr($decuri,0,$cmdlength);
   63: }
   64: 
   65: # add a randomish character after every 4th caharacter
   66: sub add_noise {
   67:     my ($uri)=@_;
   68:     my @noise=split(/(.)/,(&gettimeofday())[1]);
   69:     my $noisy;
   70:     my $i;
   71:     foreach my $chunk (split(/(....)/,$uri)) {
   72: 	$noisy.=$chunk;
   73: 	$noisy.=$noise[($i++)%(scalar@noise)];
   74:     }
   75:     return $noisy;
   76: }
   77: 
   78: # remove every fifth character
   79: sub remove_noise {
   80:     my ($uri)=@_;
   81:     my $clean;
   82:     foreach my $chunk (split(/(....)./,$uri)) { $clean.=$chunk; }
   83:     return $clean;
   84: }
   85: 
   86: sub encrypted {
   87:     my ($uri,$force_enc) = @_;
   88:     if (!$force_enc && $env{'request.role.adv'}) { return($uri); }
   89:     my $seed=&encryptseed();
   90:     unless ($seed) {
   91: 	return $uri;
   92:     }
   93:     my $cmdlength=length($uri);
   94:     # add noise before enc so that that same url's look different
   95:     $uri=&add_noise($uri);
   96:     my $noiselength=length($uri);
   97:     $uri.=time;
   98:     my $encuri='';
   99:     my $cipher=new IDEA $seed;
  100:     for (my $encidx=0;$encidx<=$noiselength;$encidx+=8) {
  101: 	$encuri.=unpack("H16",
  102: 			$cipher->encrypt(substr($uri,$encidx,8)));
  103:     }
  104:     return '/enc/'.$cmdlength.'/'.&Apache::lonnet::escape($encuri);
  105: }
  106: 
  107: sub check_encrypt {
  108:     my $str=shift;
  109:     if ($env{'request.enc'}) { return &Apache::lonenc::encrypted($str); }
  110:     return $str;
  111: }
  112: 
  113: sub check_decrypt {
  114:     my ($str)=@_;
  115:     if (ref($str)) {
  116: 	if ($$str=~m|^/enc/|) { $$str=&Apache::lonenc::unencrypted($$str); }
  117: 	return;
  118:     }
  119:     if ($str=~m|^/enc/|) { return &Apache::lonenc::unencrypted($str); }
  120:     return $str;
  121: }
  122: 
  123: sub encrypt_ref {
  124:     my ($token,$elements,$force_enc)=@_;
  125:     my $html;
  126:     if ($force_enc || $env{'request.enc'}) {
  127: 	while (my ($name,$value)= each(%{ $elements })) {
  128: 	    if (!$value) { next; }
  129: 	    my $href=&Apache::lonnet::hreflocation($Apache::lonxml::pwd[-1],$value);
  130: 	    if ($href !~ /^http:/) {
  131: 		$href = &Apache::lonenc::encrypted($href,$force_enc);
  132: 	    }
  133: 	    $token->[2]->{$name}=$href;
  134: 	}
  135: 	delete($token->[2]->{'encrypturl'});
  136: 	$html = &Apache::edit::rebuild_tag($token);
  137:     } else {
  138: 	$html = $token->[4];
  139:     }
  140:     return $html;
  141: }
  142: 1;
  143: __END__
  144: 
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