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htmlpurifier/library/HTMLPurifier/Encoder.php

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<?php
require_once 'HTMLPurifier/EntityLookup.php';
/**
* An HTML and UTF-8 specific encoder that cleans, unentity-izes and transforms.
*/
class HTMLPurifier_Encoder
{
var $_entity_lookup;
/**
* Callback regex string for parsing entities.
* @protected
*/
var $_substituteEntitiesRegex =
'/&(?:[#]x([a-fA-F0-9]+)|[#]0*(\d+)|([A-Za-z]+));?/';
// 1. hex 2. dec 3. string
/**
* Decimal to parsed string conversion table for special entities.
* @protected
*/
var $_special_dec2str =
array(
34 => '"',
38 => '&',
39 => "'",
60 => '<',
62 => '>'
);
/**
* Stripped entity names to decimal conversion table for special entities.
* @protected
*/
var $_special_ent2dec =
array(
'quot' => 34,
'amp' => 38,
'lt' => 60,
'gt' => 62
);
/**
* Substitutes non-special entities with their parsed equivalents. Since
* running this whenever you have parsed character is t3h 5uck, we run
* it before everything else.
*
* @protected
* @param $string String to have non-special entities parsed.
* @returns Parsed string.
*/
function substituteNonSpecialEntities($string) {
// it will try to detect missing semicolons, but don't rely on it
return preg_replace_callback(
$this->_substituteEntitiesRegex,
array($this, 'nonSpecialEntityCallback'),
$string
);
}
/**
* Callback function for substituteNonSpecialEntities() that does the work.
*
* @warning Though this is public in order to let the callback happen,
* calling it directly is not recommended.
* @note Based on Feyd's function at
* <http://forums.devnetwork.net/viewtopic.php?p=191404#191404>,
* which is in public domain.
* @note While we're going to do code point parsing anyway, a good
* optimization would be to refuse to translate code points that
* are non-SGML characters. However, this could lead to duplication.
* @param $matches PCRE matches array, with 0 the entire match, and
* either index 1, 2 or 3 set with a hex value, dec value,
* or string (respectively).
* @returns Replacement string.
* @todo Implement string translations
*/
// +----------+----------+----------+----------+
// | 33222222 | 22221111 | 111111 | |
// | 10987654 | 32109876 | 54321098 | 76543210 | bit
// +----------+----------+----------+----------+
// | | | | 0xxxxxxx | 1 byte 0x00000000..0x0000007F
// | | | 110yyyyy | 10xxxxxx | 2 byte 0x00000080..0x000007FF
// | | 1110zzzz | 10yyyyyy | 10xxxxxx | 3 byte 0x00000800..0x0000FFFF
// | 11110www | 10wwzzzz | 10yyyyyy | 10xxxxxx | 4 byte 0x00010000..0x0010FFFF
// +----------+----------+----------+----------+
// | 00000000 | 00011111 | 11111111 | 11111111 | Theoretical upper limit of legal scalars: 2097151 (0x001FFFFF)
// | 00000000 | 00010000 | 11111111 | 11111111 | Defined upper limit of legal scalar codes
// +----------+----------+----------+----------+
function nonSpecialEntityCallback($matches) {
// replaces all but big five
$entity = $matches[0];
$is_num = (@$matches[0][1] === '#');
if ($is_num) {
$is_hex = (@$entity[2] === 'x');
$code = $is_hex ? hexdec($matches[1]) : (int) $matches[2];
// abort for special characters
if (isset($this->_special_dec2str[$code])) return $entity;
if($code > 1114111 or $code < 0 or
($code >= 55296 and $code <= 57343) ) {
// bits are set outside the "valid" range as defined
// by UNICODE 4.1.0
return '';
}
$x = $y = $z = $w = 0;
if ($code < 128) {
// regular ASCII character
$x = $code;
} else {
// set up bits for UTF-8
$x = ($code & 63) | 128;
if ($code < 2048) {
$y = (($code & 2047) >> 6) | 192;
} else {
$y = (($code & 4032) >> 6) | 128;
if($code < 65536) {
$z = (($code >> 12) & 15) | 224;
} else {
$z = (($code >> 12) & 63) | 128;
$w = (($code >> 18) & 7) | 240;
}
}
}
// set up the actual character
$ret = '';
if($w) $ret .= chr($w);
if($z) $ret .= chr($z);
if($y) $ret .= chr($y);
$ret .= chr($x);
return $ret;
} else {
if (isset($this->_special_ent2dec[$matches[3]])) return $entity;
if (!$this->_entity_lookup) {
require_once 'HTMLPurifier/EntityLookup.php';
$this->_entity_lookup = HTMLPurifier_EntityLookup::instance();
}
if (isset($this->_entity_lookup->table[$matches[3]])) {
return $this->_entity_lookup->table[$matches[3]];
} else {
return $entity;
}
}
}
/**
* Cleans a UTF-8 string for well-formedness and SGML validity
*
* It will parse according to UTF-8 and return a valid UTF8 string, with
* non-SGML codepoints excluded.
*
* @warning This function can find a lot of use, so we may be moving
* it to a dedicated class.
*
* @note Just for reference, the non-SGML code points are 0 to 31 and
* 127 to 159, inclusive. However, we allow code points 9, 10
* and 13, which are the tab, line feed and carriage return
* respectively. 128 and above the code points map to multibyte
* UTF-8 representations.
*
* @note The functionality provided by the original function could be
* implemented with iconv using 'UTF-8//IGNORE', mbstring, or
* even the PCRE modifier 'u', these do not allow us to strip
* control characters or disallowed code points, and the latter
* does not allow invalid UTF8 characters to be ignored.
*
* @note Decomposing the string into Unicode code points is necessary
* because SGML disallows the use of specific code points, not
* necessarily bytes. A naive implementation that simply strtr
* disallowed code points as bytes will break other Unicode
* characters in which using such bytes is valid.
*
* @note Code adapted from utf8ToUnicode by Henri Sivonen and
* hsivonen@iki.fi at <http://iki.fi/hsivonen/php-utf8/> under the
* LGPL license. Notes on what changed are inside.
*/
function cleanUTF8($str) {
$mState = 0; // cached expected number of octets after the current octet
// until the beginning of the next UTF8 character sequence
$mUcs4 = 0; // cached Unicode character
$mBytes = 1; // cached expected number of octets in the current sequence
// original code involved an $out that was an array of Unicode
// codepoints. Instead of having to convert back into UTF-8, we've
// decided to directly append valid UTF-8 characters onto a string
// $out once they're done. $char accumulates raw bytes, while $mUcs4
// turns into the Unicode code point, so there's some redundancy.
$out = '';
$char = '';
$len = strlen($str);
for($i = 0; $i < $len; $i++) {
$in = ord($str{$i});
$char .= $str[$i]; // append byte to char
if (0 == $mState) {
// When mState is zero we expect either a US-ASCII character
// or a multi-octet sequence.
if (0 == (0x80 & ($in))) {
// US-ASCII, pass straight through.
if (($in <= 31 || $in == 127) &&
!($in == 9 || $in == 13 || $in == 10) // save \r\t\n
) {
// control characters, remove
} else {
$out .= $char;
}
// reset
$char = '';
$mBytes = 1;
} elseif (0xC0 == (0xE0 & ($in))) {
// First octet of 2 octet sequence
$mUcs4 = ($in);
$mUcs4 = ($mUcs4 & 0x1F) << 6;
$mState = 1;
$mBytes = 2;
} elseif (0xE0 == (0xF0 & ($in))) {
// First octet of 3 octet sequence
$mUcs4 = ($in);
$mUcs4 = ($mUcs4 & 0x0F) << 12;
$mState = 2;
$mBytes = 3;
} elseif (0xF0 == (0xF8 & ($in))) {
// First octet of 4 octet sequence
$mUcs4 = ($in);
$mUcs4 = ($mUcs4 & 0x07) << 18;
$mState = 3;
$mBytes = 4;
} elseif (0xF8 == (0xFC & ($in))) {
// First octet of 5 octet sequence.
//
// This is illegal because the encoded codepoint must be
// either:
// (a) not the shortest form or
// (b) outside the Unicode range of 0-0x10FFFF.
// Rather than trying to resynchronize, we will carry on
// until the end of the sequence and let the later error
// handling code catch it.
$mUcs4 = ($in);
$mUcs4 = ($mUcs4 & 0x03) << 24;
$mState = 4;
$mBytes = 5;
} elseif (0xFC == (0xFE & ($in))) {
// First octet of 6 octet sequence, see comments for 5
// octet sequence.
$mUcs4 = ($in);
$mUcs4 = ($mUcs4 & 1) << 30;
$mState = 5;
$mBytes = 6;
} else {
// Current octet is neither in the US-ASCII range nor a
// legal first octet of a multi-octet sequence.
$mState = 0;
$mUcs4 = 0;
$mBytes = 1;
$char = '';
}
} else {
// When mState is non-zero, we expect a continuation of the
// multi-octet sequence
if (0x80 == (0xC0 & ($in))) {
// Legal continuation.
$shift = ($mState - 1) * 6;
$tmp = $in;
$tmp = ($tmp & 0x0000003F) << $shift;
$mUcs4 |= $tmp;
if (0 == --$mState) {
// End of the multi-octet sequence. mUcs4 now contains
// the final Unicode codepoint to be output
// Check for illegal sequences and codepoints.
// From Unicode 3.1, non-shortest form is illegal
if (((2 == $mBytes) && ($mUcs4 < 0x0080)) ||
((3 == $mBytes) && ($mUcs4 < 0x0800)) ||
((4 == $mBytes) && ($mUcs4 < 0x10000)) ||
(4 < $mBytes) ||
// From Unicode 3.2, surrogate characters = illegal
(($mUcs4 & 0xFFFFF800) == 0xD800) ||
// Codepoints outside the Unicode range are illegal
($mUcs4 > 0x10FFFF)
) {
} elseif (0xFEFF != $mUcs4 && // omit BOM
!($mUcs4 >= 128 && $mUcs4 <= 159) // omit non-SGML
) {
$out .= $char;
}
// initialize UTF8 cache (reset)
$mState = 0;
$mUcs4 = 0;
$mBytes = 1;
$char = '';
}
} else {
// ((0xC0 & (*in) != 0x80) && (mState != 0))
// Incomplete multi-octet sequence.
// used to result in complete fail, but we'll reset
$mState = 0;
$mUcs4 = 0;
$mBytes = 1;
$char ='';
}
}
}
return $out;
}
/**
* Substitutes only special entities with their parsed equivalents.
*
* @notice We try to avoid calling this function because otherwise, it
* would have to be called a lot (for every parsed section).
*
* @protected
* @param $string String to have non-special entities parsed.
* @returns Parsed string.
*/
function substituteSpecialEntities($string) {
return preg_replace_callback(
$this->_substituteEntitiesRegex,
array('HTMLPurifier_Encoder', 'specialEntityCallback'),
$string);
}
/**
* Callback function for substituteSpecialEntities() that does the work.
*
* This callback has same syntax as nonSpecialEntityCallback().
*
* @warning Though this is public in order to let the callback happen,
* calling it directly is not recommended.
* @param $matches PCRE-style matches array, with 0 the entire match, and
* either index 1, 2 or 3 set with a hex value, dec value,
* or string (respectively).
* @returns Replacement string.
*/
function specialEntityCallback($matches) {
$entity = $matches[0];
$is_num = (@$matches[0][1] === '#');
if ($is_num) {
$is_hex = (@$entity[2] === 'x');
$int = $is_hex ? hexdec($matches[1]) : (int) $matches[2];
return isset($this->_special_dec2str[$int]) ?
$this->_special_dec2str[$int] :
$entity;
} else {
return isset($this->_special_ent2dec[$matches[3]]) ?
$this->_special_ent2dec[$matches[3]] :
$entity;
}
}
}
?>
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