root/tags/1.3/wp-includes/kses.php

<?php

// Added wp_ prefix to avoid conflicts with existing kses users
# kses 0.2.2 - HTML/XHTML filter that only allows some elements and attributes
# Copyright (C) 2002, 2003, 2005  Ulf Harnhammar
# *** 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!]
if (!defined('CUSTOM_TAGS'))
    define('CUSTOM_TAGS', false);

// You can override this in your my-hacks.php file
if (!CUSTOM_TAGS) {
    $allowedposttags = array(
        'address' => array(),
        'a' => array(
            'href' => array(), 'title' => array(),
            'rel' => array(), 'rev' => array(),
            'name' => array()
            ),
        'abbr' => array(
            'title' => array(), 'class' => array()
            ),
        'acronym' => array(
            'title' => array()
            ),
        'b' => array(),
        'big' => array(),
        'blockquote' => array(
            'cite' => array(), 'xml:lang' => array(),
            'lang' => array()
            ),
        'br' => array(),
        'button' => array(
            'disabled' => array(), 'name' => array(),
            'type' => array(), 'value' => array()
            ),
        'caption' => array(
            'align' => array()
            ),
        'code' => array(),
        'col' => array(
            'align' => array(), 'char' => array(),
            'charoff' => array(), 'span' => array(),
            'valign' => array(), 'width' => array()
            ),
        'del' => array(
            'datetime' => array()
            ),
        'dd' => array(),
        'div' => array(
            'align' => array(), 'xml:lang' => array(),
            'lang' => array()
            ),
        'dl' => array(),
        'dt' => array(),
        'em' => array(),
        'fieldset' => array(),
        'font' => array(
            'color' => array(), 'face' => array(),
            'size' => array()
            ),
        'form' => array(
            'action' => array(), 'accept' => array(),
            'accept-charset' => array(), 'enctype' => array(),
            'method' => array(), 'name' => array(),
            'target' => array()
            ),
        'h1' => array(
            'align' => array()
            ),
        'h2' => array(
            'align' => array()
            ),
        'h3' => array(
            'align' => array()
            ),
        'h4' => array(
            'align' => array()
            ),
        'h5' => array(
            'align' => array()
            ),
        'h6' => array(
            'align' => array()
            ),
        'hr' => array(
            'align' => array(), 'noshade' => array(),
            'size' => array(), 'width' => array()
            ),
        'i' => array(),
        'img' => array(
            'alt' => array(), 'align' => array(),
            'border' => array(), 'height' => array(),
            'hspace' => array(), 'longdesc' => array(),
            'vspace' => array(), 'src' => array(),
            'width' => array()
            ),
        'ins' => array(
            'datetime' => array(), 'cite' => array()
            ),
        'kbd' => array(),
        'label' => array(
            'for' => array()
            ),
        'legend' => array(
            'align' => array()
            ),
        'li' => array(),
        'p' => array(
            'align' => array(), 'xml:lang' => array(),
            'lang' => array()
            ),
        'pre' => array(
            'width' => array()
            ),
        'q' => array(
            'cite' => array()
            ),
        's' => array(),
        'strike' => array(),
        'strong' => array(),
        'sub' => array(),
        'sup' => array(),
        'table' => array(
            'align' => array(), 'bgcolor' => array(),
            'border' => array(), 'cellpadding' => array(),
            'cellspacing' => array(), 'rules' => array(),
            'summary' => array(), 'width' => array()
            ),
        'tbody' => array(
            'align' => array(), 'char' => array(),
            'charoff' => array(), 'valign' => array()
            ),
        'td' => array(
            'abbr' => array(), 'align' => array(),
            'axis' => array(), 'bgcolor' => array(),
            'char' => array(), 'charoff' => array(),
            'colspan' => array(), 'headers' => array(),
            'height' => array(), 'nowrap' => array(),
            'rowspan' => array(), 'scope' => array(),
            'valign' => array(), 'width' => array()
            ),
        'textarea' => array(
            'cols' => array(), 'rows' => array(),
            'disabled' => array(), 'name' => array(),
            'readonly' => array()
            ),
        'tfoot' => array(
            'align' => array(), 'char' => array(),
            'charoff' => array(), 'valign' => array()
            ),
        'th' => array(
            'abbr' => array(), 'align' => array(),
            'axis' => array(), 'bgcolor' => array(),
            'char' => array(), 'charoff' => array(),
            'colspan' => array(), 'headers' => array(),
            'height' => array(), 'nowrap' => array(),
            'rowspan' => array(), 'scope' => array(),
            'valign' => array(), 'width' => array()
            ),
        'thead' => array(
            'align' => array(), 'char' => array(),
            'charoff' => array(), 'valign' => array()
            ),
        'title' => array(),
        'tr' => array(
            'align' => array(), 'bgcolor' => array(),
            'char' => array(), 'charoff' => array(),
            'valign' => array()
            ),
        'tt' => array(),
        'u' => array(),
        'ul' => array(),
        'ol' => array(),
        'var' => array()
    );

    $allowedtags = array(
        'a' => array(
            'href' => array(), 'title' => array()
            ),
        'abbr' => array(
            'title' => array()
            ),
        'acronym' => array(
            'title' => array()
            ),
        'b' => array(),
        'blockquote' => array(
            'cite' => array()
            ),
        //    'br' => array(),
        'code' => array(),
        //    'del' => array('datetime' => array()),
        //    'dd' => array(),
        //    'dl' => array(),
        //    'dt' => array(),
        'em' => array(),
        'i' => array(),
        //    'ins' => array('datetime' => array(), 'cite' => array()),
        //    'li' => array(),
        //    'ol' => array(),
        //    'p' => array(),
        //    'q' => array(),
        'strike' => array(),
        'strong' => array(),
        //    'sub' => array(),
        //    'sup' => array(),
        //    'u' => array(),
        //    'ul' => array(),
    );
}

function wp_kses($string, $allowed_html, $allowed_protocols = array ('http', 'https', 'ftp', 'ftps', 'mailto', 'news', 'irc', 'gopher', 'nntp', 'feed', 'telnet'))
    ###############################################################################
        # 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.
        ###############################################################################
    {
    $string = wp_kses_no_null($string);
    $string = wp_kses_js_entities($string);
    $string = wp_kses_normalize_entities($string);
    $allowed_html_fixed = wp_kses_array_lc($allowed_html);
    $string = wp_kses_hook($string, $allowed_html_fixed, $allowed_protocols); // WP changed the order of these funcs and added args to wp_kses_hook
    return wp_kses_split($string, $allowed_html_fixed, $allowed_protocols);
} # function wp_kses

function wp_kses_hook($string, $allowed_html, $allowed_protocols)
###############################################################################
# You add any kses hooks here.
###############################################################################
{
    $string = apply_filters('pre_kses', $string, $allowed_html, $allowed_protocols);
    return $string;
} # function wp_kses_hook

function wp_kses_version()
###############################################################################
# This function returns kses' version number.
###############################################################################
{
    return '0.2.2';
} # function wp_kses_version

function wp_kses_split($string, $allowed_html, $allowed_protocols)
###############################################################################
# This function searches for HTML tags, no matter how malformed. It also
# matches stray ">" characters.
###############################################################################
{
    return preg_replace('%((<!--.*?(-->|$))|(<[^>]*(>|$)|>))%e',
    "wp_kses_split2('\\1', \$allowed_html, ".'$allowed_protocols)', $string);
} # function wp_kses_split

function wp_kses_split2($string, $allowed_html, $allowed_protocols)
###############################################################################
# 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.
###############################################################################
{
    $string = wp_kses_stripslashes($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 != $newstring = wp_kses($string, $allowed_html, $allowed_protocols) )
            $string = $newstring;
        if ( $string == '' )
            return '';
        return "<!--{$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 wp_kses_attr("$slash$elem", $attrlist, $allowed_html, $allowed_protocols);
} # function wp_kses_split2

function wp_kses_attr($element, $attr, $allowed_html, $allowed_protocols)
###############################################################################
# This function removes all attributes, if none are allowed for this element.
# If some are allowed it calls wp_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.
###############################################################################
{
    # 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

    $attrarr = wp_kses_hair($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 => $currval)
                if (!wp_kses_check_attr_val($arreach['value'], $arreach['vless'], $currkey, $currval)) {
                    $ok = false;
                    break;
                }

            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>";
} # function wp_kses_attr

function wp_kses_hair($attr, $allowed_protocols)
###############################################################################
# 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.
###############################################################################
{
    $attrarr = array ();
    $mode = 0;
    $attrname = '';

    # 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;
                    $attrarr[] = 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"
                    {
                    $thisval = wp_kses_bad_protocol($match[1], $allowed_protocols);

                    $attrarr[] = 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'
                    {
                    $thisval = wp_kses_bad_protocol($match[1], $allowed_protocols);

                    $attrarr[] = 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
                    {
                    $thisval = wp_kses_bad_protocol($match[1], $allowed_protocols);

                    $attrarr[] = 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
            {
            $attr = wp_kses_html_error($attr);
            $mode = 0;
        }
    } # while

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

    return $attrarr;
} # function wp_kses_hair

function wp_kses_check_attr_val($value, $vless, $checkname, $checkvalue)
###############################################################################
# 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.
###############################################################################
{
    $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