#php sanitize html

sanitize.php

<?php 

//////////////////////////////////////////// 
// sanitize function 
// thanks to: http://www.programmingtalk.com/showthread.php?t=47560&page=2&highlight=injection

function sanitize($dtype, $dlen, $data){ 

// dtype 1: allow numbers, space, and '-' 
// dtype 2: allow alpha and spaces only 
// dtype 3: allow alphanumeric, spaces, period, and '-' 
// dtype 4: allow alphanumeric w/ all punctuation 
// dtype 5: email validation chars 
// dlen: data length limit, '0' = no length limit 

// special cleanups 
$data = preg_replace("/x1a/",'', $data); 
$data = preg_replace("/x00/",'', $data); 
$data = preg_replace("|\.\./|",'', $data); // stop directory traversal 
$data = preg_replace("/--/",' - ', $data); // stop mySQL comments 
$data = preg_replace("/%3A%2F%2F/",'', $data); // stop B64 encoded '://' 

///////////////////// 

// Remove Null Characters 
// This prevents sandwiching null characters 
// between ascii characters, like Java\0script. 
$data = preg_replace('/\0+/', '', $data); 
$data = preg_replace('/(\\\\0)+/', '', $data); 


// Validate standard character entities 
// Add a semicolon if missing. We do this to enable 
// the conversion of entities to ASCII later. 
$data = preg_replace('#(&\#*\w+)[\x00-\x20]+;#u',"\\1;",$data); 

// Validate UTF16 two byte encoding (x00) 
// Just as above, adds a semicolon if missing. 
$data = preg_replace('#(&\#x*)([0-9A-F]+);*#iu',"\\1\\2;",$data); 


// URL Decode 
// Just in case stuff like this is submitted: 
// <a href="http://%77%77%77%2E%67%6F%6F%67%6C%65%2E%63%6F%6D">Google</a> 
// Note: Normally urldecode() would be easier but it removes plus signs 
$data = preg_replace("/%u0([a-z0-9]{3})/i", "&#x\\1;", $data); 
$data = preg_replace("/%([a-z0-9]{2})/i", "&#x\\1;", $data); 


// Convert character entities to ASCII 
// This permits our tests below to work reliably. 
// We only convert entities that are within tags since 
// these are the ones that will pose security problems. 
if (preg_match_all("/<(.+?)>/si", $data, $matches)) { 
for ($i = 0; $i < count($matches['0']); $i++) { 
$data = str_replace($matches['1'][$i], 
html_entity_decode($matches['1'][$i], ENT_COMPAT, $charset), $data); 
} 
} 


// Convert all tabs to spaces 
// This prevents strings like this: ja vascript 
// Note: we deal with spaces between characters later. 
$data = preg_replace("#\t+#", " ", $data); 


// Makes PHP tags safe 
// Note: XML tags are inadvertently replaced too: 
// <?xml 
// But it doesn't seem to pose a problem. Besides, only commies use xml. ;) 
$data = str_replace(array('<?php', '<?PHP', '<?', '?>'), array('&lt;?php', '&lt;?PHP', '&lt;?', '?&gt;'), $data); 


// Compact any exploded words 
// This corrects words like: j a v a s c r i p t 
// These words are compacted back to their correct state. 
$words = array('javascript', 'vbscript', 'script', 'applet', 'alert', 'document', 'write', 'cookie', 'window'); 
foreach ($words as $word) { 
$temp = ''; 
for ($i = 0; $i < strlen($word); $i++) { 
$temp .= substr($word, $i, 1)."\s*"; 
} 

$temp = substr($temp, 0, -3); 
$data = preg_replace('#'.$temp.'#s', $word, $data); 
$data = preg_replace('#'.ucfirst($temp).'#s', ucfirst($word), $data); 
} 


// Remove disallowed Javascript in links or img tags 
$data = preg_replace("#<a.+?href=.*?(alert\(|alert&\#40;|javascript\:|window\.|document\.|\.cookie|<script|<xss).*?\>.*?</a>#si", "", $data); 
$data = preg_replace("#<img.+?src=.*?(alert\(|alert&\#40;|javascript\:|window\.|document\.|\.cookie|<script|<xss).*?\>#si","", $data); 
$data = preg_replace("#<(script|xss).*?\>#si", "", $data); 

// Remove JavaScript Event Handlers 
// Note: This code is a little blunt. It removes 
// the event handler and anything up to the closing >, 
// but it's unlikely to be a problem. 

$data = preg_replace('#(<[^>]+.*?)(onblur|onchange|onclick|onfocus|onload|onmouseover|onmouseup|onmousedown|onselect|onsubmit|onunload|onkeypress|onkeydown|onkeyup|onresize)[^>]*>#iU',"\\1>",$data); 


// Sanitize naughty HTML elements 
// If a tag containing any of the words in the list 
// below is found, the tag gets converted to entities. 
// So this: <blink> 
// Becomes: &lt;blink&gt; 
$data = preg_replace('#<(/*\s*)(alert|applet|basefont|base|behavior|bgsound|blink|body|embed|expression|form|frameset|frame|head|html|ilayer|iframe|input|layer|link|meta|object|plaintext|style|script|textarea|title|xml|xss)([^>]*)>#is', "&lt;\\1\\2\\3&gt;", $data); 


// Sanitize naughty scripting elements 
// Similar to above, only instead of looking for 
// tags it looks for PHP and JavaScript commands 
// that are disallowed. Rather than removing the 
// code, it simply converts the parenthesis to entities 
// rendering the code un-executable. 
// For example: eval('some code') 
// Becomes: eval('some code') 
$data = preg_replace('#(alert|cmd|passthru|eval|exec|system|fopen|fsockopen|file|file_get_contents|readfile|unlink)(\s*)\((.*?)\)#si', "\\1\\2(\\3)", $data); 

// Final clean up 
// This adds a bit of extra precaution in case 
// something got through the above filters 
$bad = array( 
'document.cookie' => '', 
'document.write' => '', 
'window.location' => '', 
"javascript\s*:" => '', 
"Redirect\s+302" => '', 
'<!--' => '&lt;!--', 
'-->' => '--&gt;' 
); 

foreach ($bad as $key => $val) { 
$data = preg_replace("#".$key."#i", $val, $data); 
} 


///////////////////// 

if($dlen != '0'){ 
$data = substr($data, 0, $dlen); 
} 

if($dtype == '1'){ 
// allow only numeric characters, space, period, and '-' 
$data = preg_replace("/[^0-9\-\ \.]/",'', $data); 
} 

if($dtype == '2'){ 
// allow only alpha characters, '_' and space 
$data = preg_replace("/[^a-zA-Z~\ \_]/",'', $data); 
} 

if($dtype == '3'){ 
// allow only alphanumeric characters, space, '_', period, colon, and '-' 
$data = preg_replace("/[^0-9a-zA-Z~\-\ \.\:\_]/",'', $data); 
} 

if($dtype == '4'){ 
// allow only alphanumeric characters w/ punctuation + carriage returns 
$data = preg_replace("|[^0-9a-zA-Z~@#$%=:;_, \\n\\\!\^&\*\(\)\-\+\.\?\/\'\"]|",'', $data); 
} 

if($dtype == '5'){ 
// specifically for email validation 
$data = preg_replace("|[^[email protected]\-\.]|",'', $data); 
} 

$data = trim($data); 

return $data; 
} 
// end sanitize 
////////////////////////////////////////////