1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
<?php
/**
* Implements data: URI for base64 encoded images supported by GD.
*/
class HTMLPurifier_URIScheme_data extends HTMLPurifier_URIScheme {
public $browsable = true;
public $allowed_types = array(
// you better write validation code for other types if you
// decide to allow them
'image/jpeg' => true,
'image/gif' => true,
'image/png' => true,
);
// this is actually irrelevant since we only write out the path
// component
public $may_omit_host = true;
public function doValidate(&$uri, $config, $context) {
$result = explode(',', $uri->path, 2);
$is_base64 = false;
$charset = null;
$content_type = null;
if (count($result) == 2) {
list($metadata, $data) = $result;
// do some legwork on the metadata
$metas = explode(';', $metadata);
while(!empty($metas)) {
$cur = array_shift($metas);
if ($cur == 'base64') {
$is_base64 = true;
break;
}
if (substr($cur, 0, 8) == 'charset=') {
// doesn't match if there are arbitrary spaces, but
// whatever dude
if ($charset !== null) continue; // garbage
$charset = substr($cur, 8); // not used
} else {
if ($content_type !== null) continue; // garbage
$content_type = $cur;
}
}
} else {
$data = $result[0];
}
if ($content_type !== null && empty($this->allowed_types[$content_type])) {
return false;
}
if ($charset !== null) {
// error; we don't allow plaintext stuff
$charset = null;
}
$data = rawurldecode($data);
if ($is_base64) {
$raw_data = base64_decode($data);
} else {
$raw_data = $data;
}
// XXX probably want to refactor this into a general mechanism
// for filtering arbitrary content types
$file = tempnam("/tmp", "");
file_put_contents($file, $raw_data);
if (function_exists('exif_imagetype')) {
$image_code = exif_imagetype($file);
} elseif (function_exists('getimagesize')) {
set_error_handler(array($this, 'muteErrorHandler'));
$info = getimagesize($file);
restore_error_handler();
if ($info == false) return false;
$image_code = $info[2];
} else {
trigger_error("could not find exif_imagetype or getimagesize functions", E_USER_ERROR);
}
$real_content_type = image_type_to_mime_type($image_code);
if ($real_content_type != $content_type) {
// we're nice guys; if the content type is something else we
// support, change it over
if (empty($this->allowed_types[$real_content_type])) return false;
$content_type = $real_content_type;
}
// ok, it's kosher, rewrite what we need
$uri->userinfo = null;
$uri->host = null;
$uri->port = null;
$uri->fragment = null;
$uri->query = null;
$uri->path = "$content_type;base64," . base64_encode($raw_data);
return true;
}
public function muteErrorHandler($errno, $errstr) {}
}
|
