mtylerb Posted July 28, 2008 Share Posted July 28, 2008 Ok, I am so lost that it's no longer funny. I am using a CMS (FrogCMS) and its comment form keeps taking single and double quotes, and backslashes them. The problem is, those backslashes then get put into the database and then they show up in the text when viewing the comments. I am assuming that the problem is with Kses, but I'm not sure. I know, pretty much, nothing about regex and how it works. I will post Kses.php for you, in case you're not familiar. I think the reasoning behind the backslashing of the quotes is to rule out sql injection, so maybe by converting, for example, ' to ' and " to " or " ? Would that work? <?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 2 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!] function kses($string, $allowed_html, $allowed_protocols = array('http', 'https', 'ftp', '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, $allowed_protocols); } # function kses function kses_hook($string) ############################################################################### # You add any kses hooks here. ############################################################################### { return $string; } # function kses_hook function kses_version() ############################################################################### # This function returns kses' version number. ############################################################################### { return '0.2.2'; } # function kses_version function kses_split($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)', $string); } # function kses_split function kses_split2($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($string, 0, 1) != '<') return '>'; # It matched a ">" character if (!preg_match('%^<\s*(/\s*)?([a-zA-Z0-9]+)([^>]*)>?$%', $string, $matches)) return ''; # It's seriously malformed $slash = trim($matches[1]); $elem = $matches[2]; $attrlist = $matches[3]; if (!@isset($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, $allowed_protocols); } # function kses_split2 function kses_attr($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 $arreach) { if (!@isset($allowed_html[strtolower($element)] [strtolower($arreach['name'])])) continue; # the attribute is not allowed $current = $allowed_html[strtolower($element)] [strtolower($arreach['name'])]; if (!is_array($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 kses_attr function 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 $attrarr; } # function kses_hair function kses_check_attr_val($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 $ok; } # function kses_check_attr_val function kses_bad_protocol($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); $string = preg_replace('/\xad+/', '', $string); # deals with Opera "feature" $string2 = $string.'a'; while ($string != $string2) { $string2 = $string; $string = kses_bad_protocol_once($string, $allowed_protocols); } # while return $string; } # function kses_bad_protocol function kses_no_null($string) ############################################################################### # This function removes any NULL characters in $string. ############################################################################### { $string = preg_replace('/\0+/', '', $string); $string = preg_replace('/(\\\\0)+/', '', $string); return $string; } # function kses_no_null function kses_stripslashes($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('%\\\\"%', '"', $string); } # function kses_stripslashes function kses_array_lc($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 $outarray; } # function kses_array_lc function kses_js_entities($string) ############################################################################### # This function removes the HTML JavaScript entities found in early versions of # Netscape 4. ############################################################################### { return preg_replace('%&\s*\{[^}]*(\}\s*;?|$)%', '', $string); } # function kses_js_entities function kses_html_error($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*/', '', $string); } # function kses_html_error function kses_bad_protocol_once($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])*)'. '(:|:|&#[Xx]3[Aa]\s*/e', 'kses_bad_protocol_once2("\\1", $allowed_protocols)', $string); } # function kses_bad_protocol_once function kses_bad_protocol_once2($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 = preg_replace('/\xad+/', '', $string2); # deals with Opera "feature" $string2 = strtolower($string2); $allowed = false; foreach ($allowed_protocols as $one_protocol) if (strtolower($one_protocol) == $string2) { $allowed = true; break; } if ($allowed) return "$string2:"; else return ''; } # function kses_bad_protocol_once2 function kses_normalize_entities($string) ############################################################################### # This function normalizes HTML entities. It will convert "AT&T" to the correct # "AT&T", ":" to ":", "&#XYZZY;" to "&#XYZZY;" and so on. ############################################################################### { # Disarm all entities by converting & to & $string = str_replace('&', '&', $string); # Change back the allowed entities in our entity whitelist $string = preg_replace('/&([A-Za-z][A-Za-z0-9]{0,19});/', '&\\1;', $string); $string = preg_replace('/�*([0-9]{1,5});/e', 'kses_normalize_entities2("\\1")', $string); $string = preg_replace('/&#([Xx])0*(([0-9A-Fa-f]{2}){1,2});/', '&#\\1\\2;', $string); return $string; } # function kses_normalize_entities function kses_normalize_entities2($i) ############################################################################### # This function helps kses_normalize_entities() to only accept 16 bit values # and nothing more for &#number; entities. ############################################################################### { return (($i > 65535) ? "&#$i;" : "&#$i;"); } # function kses_normalize_entities2 function kses_decode_entities($string) ############################################################################### # This function decodes numeric HTML entities (A and A). It doesn't # do anything with other entities like ä, 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 $string; } # function kses_decode_entities If I'm completely wrong and have no clue what I'm talking about, I'd prefer you didn't tell me, but you'll have to anyway, I guess. I'm pretty sure Kses is the problem, since the comment function refers directly to kses, as posted below: function comment_save(&$page) { // check if we need to save a comment if ( ! isset($_POST['comment'])) return; global $__FROG_CONN__; if ($page->comment_status != Comment::OPEN) return; $data = $_POST['comment']; if (is_null($data)) return; if ( ! isset($data['author_name']) or trim($data['author_name']) == '') return; if ( ! isset($data['author_email']) or trim($data['author_email']) == '') return; if ( ! isset($data['body']) or trim($data['body']) == '') return; use_helper('Kses'); $allowed_tags = array( 'a' => array( 'href' => array(), 'title' => array() ), 'abbr' => array( 'title' => array() ), 'acronym' => array( 'title' => array() ), 'b' => array(), 'blockquote' => array( 'cite' => array() ), 'br' => array(), 'code' => array(), 'em' => array(), 'i' => array(), 'p' => array(), 'strike' => array(), 'strong' => array() ); // get the setting for comments moderations //$sql = 'SELECT value FROM '.TABLE_PREFIX.'setting WHERE name=\'auto_approve_comment\''; //$stmt = $__FROG_CONN__->prepare($sql); //$stmt->execute(); //$auto_approve_comment = (int) $stmt->fetchColumn(); $auto_approve_comment = 1; $sql = 'INSERT INTO '.TABLE_PREFIX.'comment (page_id, author_name, author_email, author_link, body, is_approved, created_on) VALUES ('. '\''.$page->id.'\', '. $__FROG_CONN__->quote(strip_tags($data['author_name'])).', '. $__FROG_CONN__->quote(strip_tags($data['author_email'])).', '. $__FROG_CONN__->quote(strip_tags($data['author_link'])).', '. $__FROG_CONN__->quote(kses($data['body'], $allowed_tags)).', '. $__FROG_CONN__->quote($auto_approve_comment).', '. $__FROG_CONN__->quote(date('Y-m-d H:i:s')).')'; $__FROG_CONN__->exec($sql); } So, can anyone see my problem, or think of a better way to fix my issue? And just so you are aware, that quote() function refers to: public function quote($string) { return "'".mysql_real_escape_string($string)."'"; } Thanks for any help you are able to provide! Quote Link to comment Share on other sites More sharing options...
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