safeHTML

<?PHP
/*Questions, comments, ideas, or improvments [email protected] 
This will take a string reference and only allow the tags and values in the approvedtags array.  All non-approved tags will be converted to the right HTML characters.  All non-approved attributes will be removed (I hope)  =P  */

function safeHTML(&$str){
	$approvedtags = array(
	"p"=>array('align'),
	"b"=>array(),
	"i"=>array(),
	"a"=>array('href', 'target'),
	"em"=>array(),
	"br"=>array(),
	"strong"=>array(),
	"blockquote"=>array(),
	"tt"=>array(),
	"hr"=>array('align', 'width', 'size', 'noshade'),
	"li"=>array('type'),
	"ol"=>array('type', 'start'),
	"ul"=>array('type'),
	"pre"=>array()
	);
	$keys = array_keys($approvedtags);
	$text=split('<',$str);
	$first = 1;
	foreach($text as $value){
		$temp=split('>',$value);
		if(count($temp) > 1){
			$end='';
			$tag=split(' ',$temp[0]);
			if($tag[0][0] == '/'){
				$end='/';
				$tag[0]=substr($tag[0],1);
			}
			if(in_array($tag[0],$keys)){
				$string.='<'.$end.$tag[0];
				for($i=1; $i<=count($tag); $i++){
					$attributes=split('=',$tag[$i]);
					if(in_array($attributes[0], $approvedtags[$tag[0]])){
						$string.=' '.$tag[$i];
					}
				}
				$string.='>';
			}else{
				$string.='&lt;'.htmlentities($value);
			}
			$string.=htmlentities($temp[1]);
		}else{
			if( ! $first){
				$string.='&lt;';
			}
			$string .= htmlentities($value);
		}
		$first = 0;
	}
	$str = $string;
}
?>