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Bug #1223: error when first resource is hidden
Also: error when first resource is encrypted

    1: # The LearningOnline Network
    2: # URL translation for encrypted filenames
    3: #
    4: # $Id: lonenc.pm,v 1.16 2006/05/30 19:47:28 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::lonnet;
   33: use Crypt::IDEA;
   34: use Time::HiRes qw(gettimeofday);
   35: use LONCAPA;
   36:  
   37: sub encryptseed {
   38:     my $seed=$env{'course.'.$env{'request.course.id'}.'.internal.encseed'};
   39:     $seed=~s/[^0-9a-f]/0/g;
   40:     $seed.='0123456789abcdef';
   41:     $seed=substr($seed.$seed,0,32);
   42:     return pack("H32",$seed);
   43: }
   44: 
   45: sub unencrypted {
   46:     my $uri=shift;
   47:     $uri=~s/^\/enc\/(\d+)\///;
   48:     my $cmdlength=$1;
   49:     my $seed=&encryptseed();
   50:     unless ($seed) {
   51: 	return '/'.$uri;
   52:     }
   53:     $uri=&unescape($uri);
   54:     my $cipher=new IDEA $seed;
   55:     my $decuri='';
   56:     for (my $encidx=0;$encidx<length($uri);$encidx+=16) {
   57: 	$decuri.=$cipher->decrypt(
   58: 				  pack("H16",substr($uri,$encidx,16))
   59: 				  );
   60:     }
   61:     $env{'request.enc'}=1;
   62:     $decuri=&remove_noise($decuri);
   63:     return substr($decuri,0,$cmdlength);
   64: }
   65: 
   66: # add a randomish character after every 4th caharacter
   67: sub add_noise {
   68:     my ($uri)=@_;
   69:     my @noise=split(/(.)/,(&gettimeofday())[1]);
   70:     my $noisy;
   71:     my $i;
   72:     foreach my $chunk (split(/(....)/,$uri)) {
   73: 	$noisy.=$chunk;
   74: 	$noisy.=$noise[($i++)%(scalar@noise)];
   75:     }
   76:     return $noisy;
   77: }
   78: 
   79: # remove every fifth character
   80: sub remove_noise {
   81:     my ($uri)=@_;
   82:     my $clean;
   83:     foreach my $chunk (split(/(....)./,$uri)) { $clean.=$chunk; }
   84:     return $clean;
   85: }
   86: 
   87: sub encrypted {
   88:     my ($uri,$force_enc) = @_;
   89:     if (!$force_enc && $env{'request.role.adv'}) { return($uri); }
   90:     my $seed=&encryptseed();
   91:     unless ($seed) {
   92: 	return $uri;
   93:     }
   94:     my $cmdlength=length($uri);
   95:     # add noise before enc so that that same url's look different
   96:     $uri=&add_noise($uri);
   97:     my $noiselength=length($uri);
   98:     $uri.=time;
   99:     my $encuri='';
  100:     my $cipher=new IDEA $seed;
  101:     for (my $encidx=0;$encidx<=$noiselength;$encidx+=8) {
  102: 	$encuri.=unpack("H16",
  103: 			$cipher->encrypt(substr($uri,$encidx,8)));
  104:     }
  105:     return '/enc/'.$cmdlength.'/'.&escape($encuri);
  106: }
  107: 
  108: sub check_encrypt {
  109:     my $str=shift;
  110:     if ($env{'request.enc'}) { return &Apache::lonenc::encrypted($str); }
  111:     return $str;
  112: }
  113: 
  114: sub check_decrypt {
  115:     my ($str)=@_;
  116:     if (ref($str)) {
  117: 	if ($$str=~m|^/enc/|) { $$str=&Apache::lonenc::unencrypted($$str); }
  118: 	return;
  119:     }
  120:     if ($str=~m|^/enc/|) { return &Apache::lonenc::unencrypted($str); }
  121:     return $str;
  122: }
  123: 
  124: sub encrypt_ref {
  125:     my ($token,$elements,$force_enc)=@_;
  126:     my $html;
  127:     if ($force_enc || $env{'request.enc'}) {
  128: 	while (my ($name,$value)= each(%{ $elements })) {
  129: 	    if (!$value) { next; }
  130: 	    my $href=&Apache::lonnet::hreflocation($Apache::lonxml::pwd[-1],$value);
  131: 	    if ($href !~ /^http:/) {
  132: 		$href = &Apache::lonenc::encrypted($href,$force_enc);
  133: 	    }
  134: 	    $token->[2]->{$name}=$href;
  135: 	}
  136: 	delete($token->[2]->{'encrypturl'});
  137: 	$html = &Apache::edit::rebuild_tag($token);
  138:     } else {
  139: 	$html = $token->[4];
  140:     }
  141:     return $html;
  142: }
  143: 1;
  144: __END__
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