From 3f71149d19bab2744d9716a786914938c742c81f Mon Sep 17 00:00:00 2001
From: saxmatt <saxmatt@1a063a9b-81f0-0310-95a4-ce76da25c4cd>
Date: Tue, 23 Dec 2003 22:09:02 +0000
Subject: [PATCH] Add kses HTML cleaning.

git-svn-id: http://svn.automattic.com/wordpress/trunk@649 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/kses.php | 528 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 528 insertions(+)
 create mode 100644 wp-includes/kses.php

diff --git a/wp-includes/kses.php b/wp-includes/kses.php
new file mode 100644
index 0000000000..5b4125b0f1
--- /dev/null
+++ b/wp-includes/kses.php
@@ -0,0 +1,528 @@
+<?php
+// Added wp_ prefix to avoid conflicts with existing kses users
+# kses 0.2.1 - HTML/XHTML filter that only allows some elements and attributes
+# Copyright (C) 2002, 2003  Ulf Harnhammar
+# *** CONTACT INFORMATION ***
+#
+# E-mail:      metaur at users dot sourceforge dot net
+# Web page:    http://sourceforge.net/projects/kses
+# Paper mail:  (not at the moment)
+#
+# [kses strips evil scripts!]
+
+
+function wp_kses($string, $allowed_html, $allowed_protocols =
+               array('http', 'https', 'ftp', 'news', 'nntp', 'telnet',
+                     'gopher', 'mailto'))
+###############################################################################
+# 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.
+###############################################################################
+{
+  $string = kses_no_null($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, $allowed_protocols);
+} # function wp_kses
+
+
+function wp_kses_hook($string)
+###############################################################################
+# You add any kses hooks here.
+###############################################################################
+{
+  return $string;
+} # function wp_kses_hook
+
+
+function wp_kses_version()
+###############################################################################
+# This function returns kses' version number.
+###############################################################################
+{
+  return '0.2.1';
+} # function wp_kses_version
+
+
+function wp_kses_split($string, $allowed_html, $allowed_protocols)
+###############################################################################
+# This function searches for HTML tags, no matter how malformed. It also
+# matches stray ">" characters.
+###############################################################################
+{
+  return preg_replace('%(<'.   # EITHER: <
+                      '[^>]*'. # things that aren't >
+                      '(>|$)'. # > or end of string
+                      '|>)%e', # OR: just a >
+                      "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.
+###############################################################################
+{
+  $string = kses_stripslashes($string);
+
+  if (substr($string, 0, 1) != '<')
+    return '&gt;';
+    # It matched a ">" character
+
+  if (!preg_match('%^<\s*(/\s*)?([a-zA-Z0-9]+)([^>]*)>?$%', $string, $matches))
+    return '';
+    # It's seriously malformed
+
+  $slash = trim($matches[1]);
+  $elem = $matches[2];
+  $attrlist = $matches[3];
+
+  if (!is_array($allowed_html[strtolower($elem)]))
+    return '';
+    # They are using a not allowed HTML element
+
+  return kses_attr("$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 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
+
+  $attrarr = kses_hair($attr, $allowed_protocols);
+
+# Go through $attrarr, and save the allowed attributes for this element
+# in $attr2
+
+  $attr2 = '';
+
+  foreach ($attrarr as $arreach)
+  {
+    $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))
+        { $ok = false; break; }
+
+      if ($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"
+        {
+          $thisval = kses_bad_protocol($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'
+        {
+          $thisval = kses_bad_protocol($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
+        {
+          $thisval = kses_bad_protocol($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
+    {
+      $attr = kses_html_error($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 $ok;
+} # function wp_kses_check_attr_val
+
+
+function wp_kses_bad_protocol($string, $allowed_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)".
+###############################################################################
+{
+  $string = kses_no_null($string);
+  $string2 = $string.'a';
+
+  while ($string != $string2)
+  {
+    $string2 = $string;
+    $string = kses_bad_protocol_once($string, $allowed_protocols);
+  } # while
+
+  return $string;
+} # function wp_kses_bad_protocol
+
+
+function wp_kses_no_null($string)
+###############################################################################
+# This function removes any NULL or chr(173) characters in $string.
+###############################################################################
+{
+  $string = preg_replace('/\0+/', '', $string);
+  $string = preg_replace('/(\\\\0)+/', '', $string);
+
+  $string = preg_replace('/\xad+/', '', $string); # deals with Opera "feature"
+
+  return $string;
+} # function wp_kses_no_null
+
+
+function wp_kses_stripslashes($string)
+###############################################################################
+# 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.
+###############################################################################
+{
+  return preg_replace('%\\\\"%', '"', $string);
+} # function wp_kses_stripslashes
+
+
+function wp_kses_array_lc($inarray)
+###############################################################################
+# This function goes through an array, and changes the keys to all lower case.
+###############################################################################
+{
+  $outarray = array();
+
+  foreach ($inarray as $inkey => $inval)
+  {
+    $outkey = strtolower($inkey);
+    $outarray[$outkey] = array();
+
+    foreach ($inval as $inkey2 => $inval2)
+    {
+      $outkey2 = strtolower($inkey2);
+      $outarray[$outkey][$outkey2] = $inval2;
+    } # foreach $inval
+  } # foreach $inarray
+
+  return $outarray;
+} # function wp_kses_array_lc
+
+
+function wp_kses_js_entities($string)
+###############################################################################
+# This function removes the HTML JavaScript entities found in early versions of
+# Netscape 4.
+###############################################################################
+{
+  return preg_replace('%&\s*\{[^}]*(\}\s*;?|$)%', '', $string);
+} # function wp_kses_js_entities
+
+
+function wp_kses_html_error($string)
+###############################################################################
+# This function deals with 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.
+###############################################################################
+{
+  return preg_replace('/^("[^"]*("|$)|\'[^\']*(\'|$)|\S)*\s*/', '', $string);
+} # function wp_kses_html_error
+
+
+function wp_kses_bad_protocol_once($string, $allowed_protocols)
+###############################################################################
+# This function searches for URL protocols at the beginning of $string, while
+# handling whitespace and HTML entities.
+###############################################################################
+{
+  return preg_replace('/^((&[^;]*;|[\sA-Za-z0-9])*)'.
+                      '(:|&#58;|&#[Xx]3[Aa];)\s*/e',
+                      'kses_bad_protocol_once2("\\1", $allowed_protocols)',
+                      $string);
+} # function wp_kses_bad_protocol_once
+
+
+function wp_kses_bad_protocol_once2($string, $allowed_protocols)
+###############################################################################
+# 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.
+###############################################################################
+{
+  $string2 = kses_decode_entities($string);
+  $string2 = preg_replace('/\s/', '', $string2);
+  $string2 = kses_no_null($string2);
+  $string2 = strtolower($string2);
+
+  $allowed = false;
+  foreach ($allowed_protocols as $one_protocol)
+    if (strtolower($one_protocol) == $string2)
+    {
+      $allowed = true;
+      break;
+    }
+
+  if ($allowed)
+    return "$string2:";
+  else
+    return '';
+} # function wp_kses_bad_protocol_once2
+
+
+function wp_kses_normalize_entities($string)
+###############################################################################
+# 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.
+###############################################################################
+{
+# Disarm all entities by converting & to &amp;
+
+  $string = str_replace('&', '&amp;', $string);
+
+# Change back the allowed entities in our entity whitelist
+
+  $string = preg_replace('/&amp;([A-Za-z][A-Za-z0-9]{0,19});/',
+                         '&\\1;', $string);
+  $string = preg_replace('/&amp;#0*([0-9]{1,5});/e',
+                         'kses_normalize_entities2("\\1")', $string);
+  $string = preg_replace('/&amp;#([Xx])0*(([0-9A-Fa-f]{2}){1,2});/',
+                         '&#\\1\\2;', $string);
+
+  return $string;
+} # function wp_kses_normalize_entities
+
+
+function wp_kses_normalize_entities2($i)
+###############################################################################
+# This function helps kses_normalize_entities() to only accept 16 bit values
+# and nothing more for &#number; entities.
+###############################################################################
+{
+  return (($i > 65535) ? "&amp;#$i;" : "&#$i;");
+} # function wp_kses_normalize_entities2
+
+
+function wp_kses_decode_entities($string)
+###############################################################################
+# 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.
+###############################################################################
+{
+  $string = preg_replace('/&#([0-9]+);/e', 'chr("\\1")', $string);
+  $string = preg_replace('/&#[Xx]([0-9A-Fa-f]+);/e', 'chr(hexdec("\\1"))',
+                         $string);
+
+  return $string;
+} # function wp_kses_decode_entities
+
+?>
\ No newline at end of file