Annotation of loncom/lonenc.pm, revision 1.25
1.1 www 1: # The LearningOnline Network
2: # URL translation for encrypted filenames
3: #
1.25 ! raeburn 4: # $Id: lonenc.pm,v 1.24 2008/12/19 14:29:13 raeburn 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;
1.11 albertel 32: use Apache::lonnet;
1.1 www 33: use Crypt::IDEA;
1.9 albertel 34: use Time::HiRes qw(gettimeofday);
1.15 www 35: use LONCAPA;
36:
1.23 foxr 37:
38: #
39: # If a module makes multiple SSI calls and some of the ssi calls result in a
40: # resource for an encoded URL, and this can be done in an unprivileged role,
41: # there must be a mechanism t oreset the 'request.enc' environment variable.
42: # This sub centralizes that mechanism:
43: #
44: sub reset_enc {
45: $env{'request.enc'} = 0;
46: }
47:
1.2 www 48: sub encryptseed {
1.19 raeburn 49: my ($cid) = @_;
50: if (!defined($cid)) {
51: $cid = $env{'request.course.id'};
52: }
53: my $seed;
54: if (defined($cid)) {
55: if (defined$env{'course.'.$cid.'.internal.encseed'}) {
56: $seed = $env{'course.'.$cid.'.internal.encseed'};
57: } else {
58: my %descargs = ( 'one_time' => 1);
59: my %course =
60: &Apache::lonnet::coursedescription($cid,\%descargs);
1.20 albertel 61: $seed = $course{'internal.encseed'};
1.19 raeburn 62: }
63: }
64: if (defined($seed)) {
65: $seed=~s/[^0-9a-f]/0/g;
66: $seed.='0123456789abcdef';
67: $seed=substr($seed.$seed,0,32);
68: return pack("H32",$seed);
69: } else {
1.21 albertel 70: return pack("H32",1);
1.19 raeburn 71: }
1.2 www 72: }
73:
1.1 www 74: sub unencrypted {
1.19 raeburn 75: my ($uri,$cid) = @_;
1.1 www 76: $uri=~s/^\/enc\/(\d+)\///;
77: my $cmdlength=$1;
1.17 albertel 78: # strip any added extension
79: $uri=~s/\.[^.]*//;
1.19 raeburn 80: my $seed=&encryptseed($cid);
1.2 www 81: unless ($seed) {
1.1 www 82: return '/'.$uri;
83: }
1.15 www 84: $uri=&unescape($uri);
1.2 www 85: my $cipher=new IDEA $seed;
1.1 www 86: my $decuri='';
87: for (my $encidx=0;$encidx<length($uri);$encidx+=16) {
88: $decuri.=$cipher->decrypt(
89: pack("H16",substr($uri,$encidx,16))
90: );
91: }
1.11 albertel 92: $env{'request.enc'}=1;
1.9 albertel 93: $decuri=&remove_noise($decuri);
1.1 www 94: return substr($decuri,0,$cmdlength);
95: }
96:
1.9 albertel 97: # add a randomish character after every 4th caharacter
98: sub add_noise {
99: my ($uri)=@_;
100: my @noise=split(/(.)/,(&gettimeofday())[1]);
101: my $noisy;
102: my $i;
103: foreach my $chunk (split(/(....)/,$uri)) {
104: $noisy.=$chunk;
105: $noisy.=$noise[($i++)%(scalar@noise)];
106: }
107: return $noisy;
108: }
109:
110: # remove every fifth character
111: sub remove_noise {
112: my ($uri)=@_;
113: my $clean;
114: foreach my $chunk (split(/(....)./,$uri)) { $clean.=$chunk; }
115: return $clean;
116: }
117:
1.1 www 118: sub encrypted {
1.12 albertel 119: my ($uri,$force_enc) = @_;
120: if (!$force_enc && $env{'request.role.adv'}) { return($uri); }
1.2 www 121: my $seed=&encryptseed();
122: unless ($seed) {
123: return $uri;
124: }
1.1 www 125: my $cmdlength=length($uri);
1.9 albertel 126: # add noise before enc so that that same url's look different
127: $uri=&add_noise($uri);
128: my $noiselength=length($uri);
129: $uri.=time;
1.1 www 130: my $encuri='';
1.2 www 131: my $cipher=new IDEA $seed;
1.9 albertel 132: for (my $encidx=0;$encidx<=$noiselength;$encidx+=8) {
1.1 www 133: $encuri.=unpack("H16",
134: $cipher->encrypt(substr($uri,$encidx,8)));
135: }
1.15 www 136: return '/enc/'.$cmdlength.'/'.&escape($encuri);
1.1 www 137: }
138:
1.5 albertel 139: sub check_encrypt {
140: my $str=shift;
1.18 raeburn 141: if (ref($str)) {
142: if ($env{'request.enc'}) { $$str = &Apache::lonenc::encrypted($$str); }
143: return;
144: } else {
145: if ($env{'request.enc'}) { return &Apache::lonenc::encrypted($str); }
146: }
1.5 albertel 147: return $str;
148: }
149:
1.6 albertel 150: sub check_decrypt {
151: my ($str)=@_;
1.7 albertel 152: if (ref($str)) {
153: if ($$str=~m|^/enc/|) { $$str=&Apache::lonenc::unencrypted($$str); }
154: return;
155: }
156: if ($str=~m|^/enc/|) { return &Apache::lonenc::unencrypted($str); }
157: return $str;
1.6 albertel 158: }
159:
1.10 albertel 160: sub encrypt_ref {
1.12 albertel 161: my ($token,$elements,$force_enc)=@_;
1.10 albertel 162: my $html;
1.12 albertel 163: if ($force_enc || $env{'request.enc'}) {
1.10 albertel 164: while (my ($name,$value)= each(%{ $elements })) {
1.22 albertel 165: next if (!$value);
166: next if ($value =~ /^\w+:/); # explict javascript: or http: link
1.10 albertel 167: my $href=&Apache::lonnet::hreflocation($Apache::lonxml::pwd[-1],$value);
1.24 raeburn 168: if ($href !~ /^https?\:/) {
1.17 albertel 169: # IE really wants an extension
170: my ($extension) = ($href =~ m/(\.[^.]*)$/);
1.25 ! raeburn 171: my $newhref = &Apache::lonenc::encrypted($href,$force_enc);
! 172: unless ($newhref eq $href) {
! 173: $href = $newhref.$extension;
! 174: }
1.12 albertel 175: }
1.10 albertel 176: $token->[2]->{$name}=$href;
177: }
1.12 albertel 178: delete($token->[2]->{'encrypturl'});
1.10 albertel 179: $html = &Apache::edit::rebuild_tag($token);
180: } else {
181: $html = $token->[4];
182: }
183: return $html;
184: }
1.1 www 185: 1;
186: __END__
187:
188:
189:
190:
191:
192:
193:
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