<?php
/**
 * kses 0.2.2 - HTML/XHTML filter that only allows some elements and attributes
 * Copyright (C) 2002, 2003, 2005  Ulf Harnhammar
 *
 * This program is free software and open source software; you can redistribute
 * it and/or modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 3 of the License,
 * or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA  or visit
 * http://www.gnu.org/licenses/gpl.html
 *
 * *** CONTACT INFORMATION ***
 *
 * E-mail:      metaur at users dot sourceforge dot net
 * Web page:    http://sourceforge.net/projects/kses
 * Paper mail:  Ulf Harnhammar
 *              Ymergatan 17 C
 *              753 25  Uppsala
 *              SWEDEN
 *
 * [kses strips evil scripts!]
 *
 * @package   chamilo.kses
 * @copyright Ulf Harnhammar  {@link http://sourceforge.net/projects/kses}
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

$kses_allowedentitynames = array(
    'nbsp',    'iexcl',  'cent',    'pound',  'curren', 'yen',
    'brvbar',  'sect',   'uml',     'copy',   'ordf',   'laquo',
    'not',     'shy',    'reg',     'macr',   'deg',    'plusmn',
    'acute',   'micro',  'para',    'middot', 'cedil',  'ordm',
    'raquo',   'iquest', 'Agrave',  'Aacute', 'Acirc',  'Atilde',
    'Auml',    'Aring',  'AElig',   'Ccedil', 'Egrave', 'Eacute',
    'Ecirc',   'Euml',   'Igrave',  'Iacute', 'Icirc',  'Iuml',
    'ETH',     'Ntilde', 'Ograve',  'Oacute', 'Ocirc',  'Otilde',
    'Ouml',    'times',  'Oslash',  'Ugrave', 'Uacute', 'Ucirc',
    'Uuml',    'Yacute', 'THORN',   'szlig',  'agrave', 'aacute',
    'acirc',   'atilde', 'auml',    'aring',  'aelig',  'ccedil',
    'egrave',  'eacute', 'ecirc',   'euml',   'igrave', 'iacute',
    'icirc',   'iuml',   'eth',     'ntilde', 'ograve', 'oacute',
    'ocirc',   'otilde', 'ouml',    'divide', 'oslash', 'ugrave',
    'uacute',  'ucirc',  'uuml',    'yacute', 'thorn',  'yuml',
    'quot',    'amp',    'lt',      'gt',     'apos',   'OElig',
    'oelig',   'Scaron', 'scaron',  'Yuml',   'circ',   'tilde',
    'ensp',    'emsp',   'thinsp',  'zwnj',   'zwj',    'lrm',
    'rlm',     'ndash',  'mdash',   'lsquo',  'rsquo',  'sbquo',
    'ldquo',   'rdquo',  'bdquo',   'dagger', 'Dagger', 'permil',
    'lsaquo',  'rsaquo', 'euro',    'fnof',   'Alpha',  'Beta',
    'Gamma',   'Delta',  'Epsilon', 'Zeta',   'Eta',    'Theta',
    'Iota',    'Kappa',  'Lambda',  'Mu',     'Nu',     'Xi',
    'Omicron', 'Pi',     'Rho',     'Sigma',  'Tau',    'Upsilon',
    'Phi',     'Chi',    'Psi',     'Omega',  'alpha',  'beta',
    'gamma',   'delta',  'epsilon', 'zeta',   'eta',    'theta',
    'iota',    'kappa',  'lambda',  'mu',     'nu',     'xi',
    'omicron', 'pi',     'rho',     'sigmaf', 'sigma',  'tau',
    'upsilon', 'phi',    'chi',     'psi',    'omega',  'thetasym',
    'upsih',   'piv',    'bull',    'hellip', 'prime',  'Prime',
    'oline',   'frasl',  'weierp',  'image',  'real',   'trade',
    'alefsym', 'larr',   'uarr',    'rarr',   'darr',   'harr',
    'crarr',   'lArr',   'uArr',    'rArr',   'dArr',   'hArr',
    'forall',  'part',   'exist',   'empty',  'nabla',  'isin',
    'notin',   'ni',     'prod',    'sum',    'minus',  'lowast',
    'radic',   'prop',   'infin',   'ang',    'and',    'or',
    'cap',     'cup',    'int',     'sim',    'cong',   'asymp',
    'ne',      'equiv',  'le',      'ge',     'sub',    'sup',
    'nsub',    'sube',   'supe',    'oplus',  'otimes', 'perp',
    'sdot',    'lceil',  'rceil',   'lfloor', 'rfloor', 'lang',
    'rang',    'loz',    'spades',  'clubs',  'hearts', 'diams',
);

/**
 * Filters content and keeps only allowable HTML elements.
 *
 * This function makes sure that only the allowed HTML element names, attribute
 * names and attribute values plus only sane HTML entities will occur in
 * $string. You have to remove any slashes from PHP's magic quotes before you
 * call this function.
 *
 * The default allowed protocols are 'http', 'https', 'ftp', 'news',
 * 'nntp', 'telnet', 'gopher', 'mailto'.
 * This covers all common link protocols, except for 'javascript' which should not
 * be allowed for untrusted users.
 *
 * @param string $string
 * @param string $allowed_html
 * @param array $allowed_protocols
 * @return string
 */
function kses($string, $allowed_html, $allowed_protocols =
               array('http', 'https', 'ftp', 'news', 'nntp', 'telnet',
                     'gopher', 'mailto'))
{
    $string = kses_no_null($string);
    $string = kses_js_entities($string);
    $string = kses_normalize_entities($string);
    $string = kses_hook($string);
    $allowed_html_fixed = kses_array_lc($allowed_html);
    return kses_split($string, $allowed_html_fixed, $allowed_protocols);
}


/**
 * You add any kses hooks here.
 *
 * @param string $string
 * @return string
 */
function kses_hook($string)
{
    return $string;
}

/**
 * This function returns kses' version number.
 *
 * @return string KSES Version Number
 */
function kses_version()
{
    return '0.2.2';
}


/**
 * This function searches for HTML tags, no matter how malformed.
 * It also matches stray ">" characters.
 *
 * @param string $string Content to filter
 * @param array $allowed_html Allowed HTML elements
 * @param array $allowed_protocols Allowed protocols to keep
 * @return string Content with fixed HTML tags
 */
function kses_split($string, $allowed_html, $allowed_protocols)
{
    global $pass_allowed_html, $pass_allowed_protocols;
    $pass_allowed_html = $allowed_html;
    $pass_allowed_protocols = $allowed_protocols;
    return preg_replace_callback( '%((<!--.*?(-->|$))|(<[^>]*(>|$)|>))%', '_kses_split_callback', $string );
}

/**
 * Callback for kses_split.
 *
 * @access private
 */
function _kses_split_callback( $match )
{
    global $pass_allowed_html, $pass_allowed_protocols;
    return kses_split2( $match[1], $pass_allowed_html, $pass_allowed_protocols );
}

/**
 * Callback for kses_split for fixing malformed HTML tags.
 *
 * This function does a lot of work. It rejects some very malformed things like
 * <:::>. It returns an empty string, if the element isn't allowed (look ma, no
 * strip_tags()!). Otherwise it splits the tag into an element and an attribute
 * list.
 *
 * After the tag is split into an element and an attribute list, it is run
 * through another filter which will remove illegal attributes and once that is
 * completed, will be returned.
 *
 * @access private
 * @uses kses_attr()
 *
 * @param string $string Content to filter
 * @param array $allowed_html Allowed HTML elements
 * @param array $allowed_protocols Allowed protocols to keep
 * @return string Fixed HTML element
 */
function kses_split2($string, $allowed_html, $allowed_protocols)
{
    $string = kses_stripslashes($string);

    if (substr($string, 0, 1) != '<')
        return '&gt;';
    // It matched a ">" character

    if (preg_match('%^<!--(.*?)(-->)?$%', $string, $matches)) {
        $string = str_replace(array('<!--', '-->'), '', $matches[1]);
        while ( $string != $newstring = kses($string, $allowed_html, $allowed_protocols) )
            $string = $newstring;
        if ( $string == '' )
            return '';
        // prevent multiple dashes in comments
        $string = preg_replace('/--+/', '-', $string);
        // prevent three dashes closing a comment
        $string = preg_replace('/-$/', '', $string);
        return "<!--{$string}-->";
    }
    // Allow HTML comments

    if (!preg_match('%^<\s*(/\s*)?([a-zA-Z0-9]+)([^>]*)>?$%', $string, $matches))
        return '';
    // It's seriously malformed

    $slash = trim($matches[1]);
    $elem = $matches[2];
    $attrlist = $matches[3];

    if (!@isset($allowed_html[strtolower($elem)]))
        return '';
    // They are using a not allowed HTML element

    if ($slash != '')
        return "<$slash$elem>";
    // No attributes are allowed for closing elements

    return kses_attr("$slash$elem", $attrlist, $allowed_html,
                   $allowed_protocols);
}

/**
 * This function removes all attributes, if none are allowed for this element.
 *
 * If some are allowed it calls kses_hair() to split them further, and then
 * it builds up new HTML code from the data that kses_hair() returns. It also
 * removes "<" and ">" characters, if there are any left. One more thing it does
 * is to check if the tag has a closing XHTML slash, and if it does, it puts one
 * in the returned code as well.
 *
 * @param string $element HTML element/tag
 * @param string $attr HTML attributes from HTML element to closing HTML element tag
 * @param array $allowed_html Allowed HTML elements
 * @param array $allowed_protocols Allowed protocols to keep
 * @return string Sanitized HTML element
 */
function kses_attr($element, $attr, $allowed_html, $allowed_protocols)
{
    // Is there a closing XHTML slash at the end of the attributes?

    $xhtml_slash = '';
    if (preg_match('%\s*/\s*$%', $attr))
        $xhtml_slash = ' /';

    // Are any attributes allowed at all for this element?

    if (@count($allowed_html[strtolower($element)]) == 0)
        return "<$element$xhtml_slash>";

    // Split it

    $attrarr = kses_hair($attr, $allowed_protocols);

    // Go through $attrarr, and save the allowed attributes for this element
    // in $attr2

    $attr2 = '';

    foreach ($attrarr as $arreach)
    {
        if (!@isset($allowed_html[strtolower($element)]
                              [strtolower($arreach['name'])]))
            continue; // the attribute is not allowed

        $current = $allowed_html[strtolower($element)]
                              [strtolower($arreach['name'])];
        if ($current == '')
            continue; // the attribute is not allowed

        if (!is_array($current))
            $attr2 .= ' '.$arreach['whole'];
        // there are no checks

        else
        {
            // there are some checks
            $ok = true;
            foreach ($current as $currkey => $currval)
                if (!kses_check_attr_val($arreach['value'], $arreach['vless'],
                                 $currkey, $currval))
                { $ok = false; break; }

            if ( strtolower($arreach['name']) == 'style' ) {
                $orig_value = $arreach['value'];

                $value = kses_safecss_filter_attr($orig_value);

                if ( empty($value) )
                    continue;

                $arreach['value'] = $value;

                $arreach['whole'] = str_replace($orig_value, $value, $arreach['whole']);
            }

            if ($ok)
                $attr2 .= ' '.$arreach['whole']; // it passed them
        } // if !is_array($current)
    } // foreach

    // Remove any "<" or ">" characters

    $attr2 = preg_replace('/[<>]/', '', $attr2);

    return "<$element$attr2$xhtml_slash>";
}

/**
 * Builds an attribute list from string containing attributes.
 *
 * This function does a lot of work. It parses an attribute list into an array
 * with attribute data, and tries to do the right thing even if it gets weird
 * input. It will add quotes around attribute values that don't have any quotes
 * or apostrophes around them, to make it easier to produce HTML code that will
 * conform to W3C's HTML specification. It will also remove bad URL protocols
 * from attribute values.
 * It also reduces duplicate attributes by using the
 * attribute defined first (foo='bar' foo='baz' will result in foo='bar').
 *
 * @param string $attr Attribute list from HTML element to closing HTML element tag
 * @param array $allowed_protocols Allowed protocols to keep
 * @return array List of attributes after parsing
 */
function kses_hair($attr, $allowed_protocols)
{
    $attrarr = array();
    $mode = 0;
    $attrname = '';
    $uris = array('xmlns', 'profile', 'href', 'src', 'cite', 'classid', 'codebase', 'data', 'usemap', 'longdesc', 'action');

    // Loop through the whole attribute list

    while (strlen($attr) != 0)
    {
        $working = 0; // Was the last operation successful?

        switch ($mode)
        {
            case 0: // attribute name, href for instance

                if (preg_match('/^([-a-zA-Z]+)/', $attr, $match))
                {
                    $attrname = $match[1];
                    $working = $mode = 1;
                    $attr = preg_replace('/^[-a-zA-Z]+/', '', $attr);
                }

                break;

            case 1: // equals sign or valueless ("selected")

                if (preg_match('/^\s*=\s*/', $attr)) // equals sign
                {
                    $working = 1; $mode = 2;
                    $attr = preg_replace('/^\s*=\s*/', '', $attr);
                    break;
                }

                if (preg_match('/^\s+/', $attr)) // valueless
                {
                    $working = 1; $mode = 0;
                    if(FALSE === array_key_exists($attrname, $attrarr)) {
                        $attrarr[$attrname] = array ('name' => $attrname, 'value' => '', 'whole' => $attrname, 'vless' => 'y');
                    }
                    $attr = preg_replace('/^\s+/', '', $attr);
                }

                break;

            case 2: // attribute value, a URL after href= for instance

                if (preg_match('%^"([^"]*)"(\s+|/?$)%', $attr, $match))
                    // "value"
                {
                    // MDL-2684 - kses stripping CSS styles that it thinks look like protocols
                    if ($attrname == 'style') {
                        $thisval = $match[1];
                    } else {
                        $thisval = $match[1];
                        if ( in_array(strtolower($attrname), $uris) )
                            $thisval = kses_bad_protocol($thisval, $allowed_protocols);
                    }

                    if(FALSE === array_key_exists($attrname, $attrarr)) {
                        $attrarr[$attrname] = array ('name' => $attrname, 'value' => $thisval, 'whole' => "$attrname=\"$thisval\"", 'vless' => 'n');
                    }
                    $working = 1; $mode = 0;
                    $attr = preg_replace('/^"[^"]*"(\s+|$)/', '', $attr);
                    break;
                }

                if (preg_match("%^'([^']*)'(\s+|/?$)%", $attr, $match))
                    // 'value'
                {
                    $thisval = $match[1];
                    if ( in_array(strtolower($attrname), $uris) )
                        $thisval = kses_bad_protocol($thisval, $allowed_protocols);

                    if(FALSE === array_key_exists($attrname, $attrarr)) {
                        $attrarr[$attrname] = array ('name' => $attrname, 'value' => $thisval, 'whole' => "$attrname='$thisval'", 'vless' => 'n');
                    }
                    $working = 1; $mode = 0;
                    $attr = preg_replace("/^'[^']*'(\s+|$)/", '', $attr);
                    break;
                }

                if (preg_match("%^([^\s\"']+)(\s+|/?$)%", $attr, $match))
                    // value
                {
                    $thisval = $match[1];
                    if ( in_array(strtolower($attrname), $uris) )
                        $thisval = kses_bad_protocol($thisval, $allowed_protocols);

                    if(FALSE === array_key_exists($attrname, $attrarr)) {
                        $attrarr[$attrname] = array ('name' => $attrname, 'value' => $thisval, 'whole' => "$attrname=\"$thisval\"", 'vless' => 'n');
                    }
                    // We add quotes to conform to W3C's HTML spec.
                    $working = 1; $mode = 0;
                    $attr = preg_replace("%^[^\s\"']+(\s+|$)%", '', $attr);
                }

                break;
        } // switch

        if ($working == 0) // not well formed, remove and try again
        {
            $attr = kses_html_error($attr);
            $mode = 0;
        }
    } // while

    if ($mode == 1 && FALSE === array_key_exists($attrname, $attrarr))
        // special case, for when the attribute list ends with a valueless
        // attribute like "selected"
        $attrarr[$attrname] = array ('name' => $attrname, 'value' => '', 'whole' => $attrname, 'vless' => 'y');

    return $attrarr;
}

/**
 * This function performs different checks for attribute values.
 *
 * The currently implemented checks are "maxlen", "minlen", "maxval", "minval"
 * and "valueless" with even more checks to come soon.
 *
 * @param string $value Attribute value
 * @param string $vless Whether the value is valueless. Use 'y' or 'n'
 * @param string $checkname What $checkvalue is checking for.
 * @param mixed $checkvalue What constraint the value should pass
 * @return bool Whether check passes
 */
function kses_check_attr_val($value, $vless, $checkname, $checkvalue)
{
    $ok = true;

    switch (strtolower($checkname))
    {
        case 'maxlen':
            // The maxlen check makes sure that the attribute value has a length not
            // greater than the given value. This can be used to avoid Buffer Overflows
            // in WWW clients and various Internet servers.

            if (strlen($value) > $checkvalue)
                $ok = false;
            break;

        case 'minlen':
            // The minlen check makes sure that the attribute value has a length not
            // smaller than the given value.

            if (strlen($value) < $checkvalue)
                $ok = false;
            break;

        case 'maxval':
            // The maxval check does two things: it checks that the attribute value is
            // an integer from 0 and up, without an excessive amount of zeroes or
            // whitespace (to avoid Buffer Overflows). It also checks that the attribute
            // value is not greater than the given value.
            // This check can be used to avoid Denial of Service attacks.

            if (!preg_match('/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value))
                $ok = false;
            if ($value > $checkvalue)
                $ok = false;
            break;

        case 'minval':
            // The minval check checks that the attribute value is a positive integer,
            // and that it is not smaller than the given value.

            if (!preg_match('/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value))
                $ok = false;
            if ($value < $checkvalue)
                $ok = false;
            break;

        case 'valueless':
            // The valueless check checks if the attribute has a value
            // (like <a href="blah">) or not (<option selected>). If the given value
            // is a "y" or a "Y", the attribute must not have a value.
            // If the given value is an "n" or an "N", the attribute must have one.

            if (strtolower($checkvalue) != $vless)
                $ok = false;
            break;
    } // switch

    return $ok;
}

/**
 * Sanitize string from bad protocols.
 *
 * This function removes all non-allowed protocols from the beginning of
 * $string. It ignores whitespace and the case of the letters, and it does
 * understand HTML entities. It does its work in a while loop, so it won't be
 * fooled by a string like "javascript:javascript:alert(57)".
 *
 * @param string $string Content to filter bad protocols from
 * @param array $allowed_protocols Allowed protocols to keep
 * @return string Filtered content
 */
function kses_bad_protocol($string, $allowed_protocols)
{
    $string = kses_no_null($string);
    $string = preg_replace('/([^\xc3-\xcf])\xad+/', '\\1', $string); // deals with Opera "feature" -- moodle utf8 fix
    $string2 = $string.'a';

    while ($string != $string2)
    {
        $string2 = $string;
        $string = kses_bad_protocol_once($string, $allowed_protocols);
    } // while

    return $string;
}

/**
 * This function removes any NULL characters in $string.
 *
 * @param string $string
 * @return string
 */
function kses_no_null($string)
{
    $string = preg_replace('/\0+/', '', $string);
    $string = preg_replace('/(\\\\0)+/', '', $string);

    return $string;
}


/**
 * Strips slashes from in front of quotes.
 *
 * This function changes the character sequence  \"  to just  "
 * It leaves all other slashes alone. It's really weird, but the quoting from
 * preg_replace(//e) seems to require this.
 *
 * @param string $string String to strip slashes
 * @return string Fixed strings with quoted slashes
 */
function kses_stripslashes($string)
{
    return preg_replace('%\\\\"%', '"', $string);
}


/**
 * This function goes through an array, and changes the keys to all lower case.
 *
 * @param array $inarray Unfiltered array
 * @return array Fixed array with all lowercase keys
 */
function kses_array_lc($inarray)
{
    $outarray = array();

    foreach ( (array) $inarray as $inkey => $inval)
    {
        $outkey = strtolower($inkey);
        $outarray[$outkey] = array();

        foreach ( (array) $inval as $inkey2 => $inval2)
        {
            $outkey2 = strtolower($inkey2);
            $outarray[$outkey][$outkey2] = $inval2;
        } // foreach $inval
    } // foreach $inarray

    return $outarray;
}

/**
 * This function removes the HTML JavaScript entities found in early versions of Netscape 4.
 *
 * @param string $string
 * @return string
 */
function kses_js_entities($string)
{
    return preg_replace('%&\s*\{[^}]*(\}\s*;?|$)%', '', $string);
}

/**
 * This function handles parsing errors in kses_hair().
 *
 * The general plan is to remove everything to and including some whitespace,
 * but it deals with quotes and apostrophes as well.
 *
 * @param string $string
 * @return string
 */
function kses_html_error($string)
{
    return preg_replace('/^("[^"]*("|$)|\'[^\']*(\'|$)|\S)*\s*/', '', $string);
}

/**
 * Sanitizes content from bad protocols and other characters.
 *
 * This function searches for URL protocols at the beginning of $string, while
 * handling whitespace and HTML entities.
 *
 * @param string $string Content to check for bad protocols
 * @param string $allowed_protocols Allowed protocols
 * @return string Sanitized content
 */
function kses_bad_protocol_once($string, $allowed_protocols)
{
    $string2 = preg_split('/:|&#0*58;|&#x0*3a;|&colon;/i', $string, 2);
    if(isset($string2[1]) && !preg_match('%/\?%',$string2[0]))
    {
        $string = kses_bad_protocol_once2($string2[0],$allowed_protocols).trim($string2[1]);
    }
    return $string;
}

/**
 * Callback for kses_bad_protocol_once() regular expression.
 *
 * This function processes URL protocols, checks to see if they're in the
 * white-list or not, and returns different data depending on the answer.
 *
 * @access private
 *
 * @param string $string URI scheme to check against the whitelist
 * @param string $allowed_protocols Allowed protocols
 * @return string Sanitized content
 */
function kses_bad_protocol_once2($string, $allowed_protocols)
{
    $string2 = kses_decode_entities($string);
    $string2 = preg_replace('/\s/', '', $string2);
    $string2 = kses_no_null($string2);
    $string2 = preg_replace('/\xad+/', '', $string2); // deals with Opera "feature"
    $string2 = strtolower($string2);

    $allowed = false;
    foreach ( (array) $allowed_protocols as $one_protocol)
        if (strtolower($one_protocol) == $string2)
        {
            $allowed = true;
            break;
        }

    if ($allowed)
        return "$string2:";
    else
        return '';
}

/**
 * Converts and fixes HTML entities.
 *
 * This function normalizes HTML entities. It will convert "AT&T" to the correct
 * "AT&amp;T", "&#00058;" to "&#58;", "&#XYZZY;" to "&amp;#XYZZY;" and so on.
 *
 * @param string $string Content to normalize entities
 * @return string Content with normalized entities
 */
function kses_normalize_entities($string)
{
    // Disarm all entities by converting & to &amp;

    $string = str_replace('&', '&amp;', $string);

    // Change back the allowed entities in our entity whitelist

    $string = preg_replace_callback('/&amp;([A-Za-z]{2,8});/', 'kses_named_entities', $string);
    $string = preg_replace_callback('/&amp;#(0*[0-9]{1,7});/', 'kses_normalize_entities2', $string);
    $string = preg_replace_callback('/&amp;#[Xx](0*[0-9A-Fa-f]{1,6});/', 'kses_normalize_entities3', $string);

    return $string;
}

/**
 * Callback for kses_normalize_entities() regular expression.
 *
 * This function only accepts valid named entity references, which are finite,
 * case-sensitive, and highly scrutinized by HTML and XML validators.
 *
 * @since 3.0.0
 *
 * @param array $matches preg_replace_callback() matches array
 * @return string Correctly encoded entity
 */
function kses_named_entities($matches) {
    global $kses_allowedentitynames;

    if ( empty($matches[1]) )
        return '';

    $i = $matches[1];
    return ( ( ! in_array($i, $kses_allowedentitynames) ) ? "&amp;$i;" : "&$i;" );
}

/**
 * Callback for kses_normalize_entities() regular expression.
 *
 * This function helps kses_normalize_entities() to only accept 16 bit values
 * and nothing more for &#number; entities.
 *
 * @access private
 *
 * @param array $matches preg_replace_callback() matches array
 * @return string Correctly encoded entity
 */
function kses_normalize_entities2($matches) {
    if ( empty($matches[1]) )
        return '';

    $i = $matches[1];
    if (kses_valid_unicode($i)) {
        $i = str_pad(ltrim($i,'0'), 3, '0', STR_PAD_LEFT);
        $i = "&#$i;";
    } else {
        $i = "&amp;#$i;";
    }

    return $i;
}

/**
 * Callback for kses_normalize_entities() for regular expression.
 *
 * This function helps kses_normalize_entities() to only accept valid Unicode
 * numeric entities in hex form.
 *
 * @access private
 *
 * @param array $matches preg_replace_callback() matches array
 * @return string Correctly encoded entity
 */
function kses_normalize_entities3($matches) {
    if ( empty($matches[1]) )
        return '';

    $hexchars = $matches[1];
    return ( ( ! kses_valid_unicode(hexdec($hexchars)) ) ? "&amp;#x$hexchars;" : '&#x'.ltrim($hexchars,'0').';' );
}

/**
 * Helper function to determine if a Unicode value is valid.
 *
 * @param int $i Unicode value
 * @return bool true if the value was a valid Unicode number
 */
function kses_valid_unicode($i) {
    return ( $i == 0x9 || $i == 0xa || $i == 0xd ||
            ($i >= 0x20 && $i <= 0xd7ff) ||
            ($i >= 0xe000 && $i <= 0xfffd) ||
            ($i >= 0x10000 && $i <= 0x10ffff) );
}

/**
 * Convert all entities to their character counterparts.
 *
 * This function decodes numeric HTML entities (&#65; and &#x41;). It doesn't do
 * anything with other entities like &auml;, but we don't need them in the URL
 * protocol whitelisting system anyway.
 *
 * @param string $string Content to change entities
 * @return string Content after decoded entities
 */
function kses_decode_entities($string)
{
    $string = preg_replace_callback('/&#([0-9]+);/', '_kses_decode_entities_chr', $string);
    $string = preg_replace_callback('/&#[Xx]([0-9A-Fa-f]+);/', '_kses_decode_entities_chr_hexdec', $string);

    return $string;
}

/**
 * Regex callback for kses_decode_entities()
 *
 * @param array $match preg match
 * @return string
 */
function _kses_decode_entities_chr( $match ) {
    return chr( $match[1] );
}

/**
 * Regex callback for kses_decode_entities()
 *
 * @param array $match preg match
 * @return string
 */
function _kses_decode_entities_chr_hexdec( $match ) {
    return chr( hexdec( $match[1] ) );
}

/**
 * Inline CSS filter
 *
 */
function kses_safecss_filter_attr( $css ) {

    $css = kses_no_null($css);
    $css = str_replace(array("\n","\r","\t"), '', $css);

    if ( preg_match( '%[\\(&=}]|/\*%', $css ) ) // remove any inline css containing \ ( & } = or comments
        return '';

    $css_array = explode( ';', trim( $css ) );
    $allowed_attr = array( 'text-align', 'margin', 'color', 'float',
        'border', 'background', 'background-color', 'border-bottom', 'border-bottom-color',
        'border-bottom-style', 'border-bottom-width', 'border-collapse', 'border-color', 'border-left',
        'border-left-color', 'border-left-style', 'border-left-width', 'border-right', 'border-right-color',
        'border-right-style', 'border-right-width', 'border-spacing', 'border-style', 'border-top',
        'border-top-color', 'border-top-style', 'border-top-width', 'border-width', 'caption-side',
        'clear', 'cursor', 'direction', 'display', 'font', 'font-family', 'font-size', 'font-style',
        'font-variant', 'font-weight', 'height', 'letter-spacing', 'line-height', 'margin-bottom',
        'margin-left', 'margin-right', 'margin-top', 'overflow', 'padding', 'padding-bottom',
        'padding-left', 'padding-right', 'padding-top', 'text-decoration', 'text-indent', 'vertical-align',
        'width' );

    if ( empty($allowed_attr) )
        return $css;

    $css = '';
    foreach ( $css_array as $css_item ) {
        if ( $css_item == '' )
            continue;
        $css_item = trim( $css_item );
        $found = false;
        if ( strpos( $css_item, ':' ) === false ) {
            $found = true;
        } else {
            $parts = split( ':', $css_item );
            if ( in_array( strtolower( trim( $parts[0] ) ), $allowed_attr ) )
                $found = true;
        }
        if ( $found ) {
            if( $css != '' )
                $css .= ';';
            $css .= $css_item;
        }
    }

    return $css;
}
