Annotation of loncom/lonenc.pm, revision 1.13
1.1 www 1: # The LearningOnline Network
2: # URL translation for encrypted filenames
3: #
1.13 ! albertel 4: # $Id: lonenc.pm,v 1.12 2006/03/22 19:37:44 albertel Exp $
1.1 www 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);
1.11 albertel 33: use Apache::lonnet;
1.1 www 34: use Apache::File();
35: use Apache::loncommon;
36: use Crypt::IDEA;
1.9 albertel 37: use Time::HiRes qw(gettimeofday);
1.1 www 38:
39: sub handler {
40: my $r = shift;
41: my %cookies=CGI::Cookie->parse($r->header_in('Cookie'));
42: my $lonid=$cookies{'lonID'};
43: my $cookie;
44: if ($lonid) {
45: my $handle=$lonid->value;
46: $handle=~s/\W//g;
47: my $lonidsdir=$r->dir_config('lonIDsDir');
1.11 albertel 48: $env{'request.enc'}=1;
1.1 www 49: if ((-e "$lonidsdir/$handle.id") && ($handle ne '')) {
50: # Initialize Environment
51: &Apache::lonnet::transfer_profile_to_env($lonidsdir,$handle);
52: # Decrypt URL and redirect
1.8 albertel 53: my $redirect=&unencrypted($r->uri);
54: if ($r->args) { $redirect.='?'.$r->args; }
55: $r->internal_redirect($redirect);
1.1 www 56: return OK;
57: }
58: }
59: return FORBIDDEN;
60: }
61:
1.2 www 62: sub encryptseed {
1.11 albertel 63: my $seed=$env{'course.'.$env{'request.course.id'}.'.internal.encseed'};
1.2 www 64: $seed=~s/[^0-9a-f]/0/g;
65: $seed.='0123456789abcdef';
66: $seed=substr($seed.$seed,0,32);
67: return pack("H32",$seed);
68: }
69:
1.1 www 70: sub unencrypted {
71: my $uri=shift;
72: $uri=~s/^\/enc\/(\d+)\///;
73: my $cmdlength=$1;
1.2 www 74: my $seed=&encryptseed();
75: unless ($seed) {
1.1 www 76: return '/'.$uri;
77: }
78: $uri=&Apache::lonnet::unescape($uri);
1.2 www 79: my $cipher=new IDEA $seed;
1.1 www 80: my $decuri='';
81: for (my $encidx=0;$encidx<length($uri);$encidx+=16) {
82: $decuri.=$cipher->decrypt(
83: pack("H16",substr($uri,$encidx,16))
84: );
85: }
1.11 albertel 86: $env{'request.enc'}=1;
1.9 albertel 87: $decuri=&remove_noise($decuri);
1.1 www 88: return substr($decuri,0,$cmdlength);
89: }
90:
1.9 albertel 91: # add a randomish character after every 4th caharacter
92: sub add_noise {
93: my ($uri)=@_;
94: my @noise=split(/(.)/,(&gettimeofday())[1]);
95: my $noisy;
96: my $i;
97: foreach my $chunk (split(/(....)/,$uri)) {
98: $noisy.=$chunk;
99: $noisy.=$noise[($i++)%(scalar@noise)];
100: }
101: return $noisy;
102: }
103:
104: # remove every fifth character
105: sub remove_noise {
106: my ($uri)=@_;
107: my $clean;
108: foreach my $chunk (split(/(....)./,$uri)) { $clean.=$chunk; }
109: return $clean;
110: }
111:
1.1 www 112: sub encrypted {
1.12 albertel 113: my ($uri,$force_enc) = @_;
114: if (!$force_enc && $env{'request.role.adv'}) { return($uri); }
1.2 www 115: my $seed=&encryptseed();
116: unless ($seed) {
117: return $uri;
118: }
1.1 www 119: my $cmdlength=length($uri);
1.9 albertel 120: # add noise before enc so that that same url's look different
121: $uri=&add_noise($uri);
122: my $noiselength=length($uri);
123: $uri.=time;
1.1 www 124: my $encuri='';
1.2 www 125: my $cipher=new IDEA $seed;
1.9 albertel 126: for (my $encidx=0;$encidx<=$noiselength;$encidx+=8) {
1.1 www 127: $encuri.=unpack("H16",
128: $cipher->encrypt(substr($uri,$encidx,8)));
129: }
130: return '/enc/'.$cmdlength.'/'.&Apache::lonnet::escape($encuri);
131: }
132:
1.5 albertel 133: sub check_encrypt {
134: my $str=shift;
1.11 albertel 135: if ($env{'request.enc'}) { return &Apache::lonenc::encrypted($str); }
1.5 albertel 136: return $str;
137: }
138:
1.6 albertel 139: sub check_decrypt {
140: my ($str)=@_;
1.7 albertel 141: if (ref($str)) {
142: if ($$str=~m|^/enc/|) { $$str=&Apache::lonenc::unencrypted($$str); }
143: return;
144: }
145: if ($str=~m|^/enc/|) { return &Apache::lonenc::unencrypted($str); }
146: return $str;
1.6 albertel 147: }
148:
1.10 albertel 149: sub encrypt_ref {
1.12 albertel 150: my ($token,$elements,$force_enc)=@_;
1.10 albertel 151: my $html;
1.12 albertel 152: if ($force_enc || $env{'request.enc'}) {
1.10 albertel 153: while (my ($name,$value)= each(%{ $elements })) {
154: if (!$value) { next; }
155: my $href=&Apache::lonnet::hreflocation($Apache::lonxml::pwd[-1],$value);
1.12 albertel 156: if ($href !~ /^http:/) {
157: $href = &Apache::lonenc::encrypted($href,$force_enc);
158: }
1.10 albertel 159: $token->[2]->{$name}=$href;
160: }
1.12 albertel 161: delete($token->[2]->{'encrypturl'});
1.10 albertel 162: $html = &Apache::edit::rebuild_tag($token);
163: } else {
164: $html = $token->[4];
165: }
166: return $html;
167: }
1.1 www 168: 1;
169: __END__
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