lib_filter.php

charset : UTF-8 支援IE, Firefox等瀏覽器

<?php
	#
	# lib_filter.txt
	#
	# A PHP HTML filtering library
	#
	# $Id: lib_filter.php,v 1.6 2005/02/02 22:35:01 cal Exp $
	#
	# http://iamcal.com/publish/articles/php/processing_html/
	# http://iamcal.com/publish/articles/php/processing_html_part_2/
	#
	# (C)2001-2004 Cal Henderson <[e-mail]>
	#
	#

	//$filter = new lib_filter();

	class lib_filter {

		var $tag_counts = array();

		#
		# tags and attributes that are allowed
		#

		var $allowed = array(
			'a'      => array('href', 'target', 'title', 'rel'),
			'strong' => array(),
			'em'     => array(),
			'code'   => array(),
			'u'      => array(),
			'b'      => array(),
			'i'      => array(),
			//'img' => array('src', 'width', 'height', 'alt'),
		);


		#
		# tags which should always be self-closing (e.g. "<img />")
		#

		var $no_close = array(
			//'img',
		);


		#
		# tags which must always have seperate opening and closing tags (e.g. "<b></b>")
		#

		var $always_close = array(
			'a',
			'u',
			'b',
			'i',
			'em',
			'code',
			'strong',
		);


		#
		# attributes which should be checked for valid protocols
		#

		var $protocol_attributes = array(
			//'src',
			'href',
		);


		#
		# protocols which are allowed
		#

		var $allowed_protocols = array(
			'http',
			'ftp',
			'mailto',
		);


		#
		# tags which should be removed if they contain no content (e.g. "<b></b>" or "<b />")
		#

		var $remove_blanks = array(
			'a',
			'u',
			'b',
			'i',
			'em',
			'code',
			'strong',
		);


		#
		# should we remove comments?
		#

		var $strip_comments = 1;


		#
		# should we try and make a b tag out of "b>"
		#

		var $always_make_tags = 1;


		###############################################################

		function go($data){

			$this->tag_counts = array();

			$data = $this->escape_comments($data);
			$data = $this->balance_html($data);
			$data = $this->check_tags($data);
			$data = $this->process_remove_blanks($data);

			return $data;
		}

		###############################################################

		function escape_comments($data){

			$data = preg_replace("/<!--(.*?)-->/se", "'<!--'.HtmlSpecialChars(StripSlashes('\\1')).'-->'", $data);

			return $data;
		}

		###############################################################

		function balance_html($data){

			if ($this->always_make_tags){

				#
				# try and form html
				#

				$data = preg_replace("/^>/", "", $data);
				$data = preg_replace("/<([^>]*?)(?=<|$)/", "<$1>", $data);
				$data = preg_replace("/(^|>)([^<]*?)(?=>)/", "$1<$2", $data);

			}else{

				#
				# escape stray brackets
				#

				$data = preg_replace("/<([^>]*?)(?=<|$)/", "&lt;$1", $data);
				$data = preg_replace("/(^|>)([^<]*?)(?=>)/", "$1$2&gt;<", $data);

				#
				# the last regexp causes '<>' entities to appear
				# (we need to do a lookahead assertion so that the last bracket can
				# be used in the next pass of the regexp)
				#

				$data = str_replace('<>', '', $data);
			}

			#echo "::".HtmlSpecialChars($data)."<br />\n";

			return $data;
		}

		###############################################################

		function check_tags($data){

			$data = preg_replace("/<(.*?)>/se", "\$this->process_tag(StripSlashes('\\1'))",	$data);

			foreach(array_keys($this->tag_counts) as $tag){
				for($i=0; $i<$this->tag_counts[$tag]; $i++){
					$data .= "</$tag>";
				}
			}

			return $data;
		}

		###############################################################

		function process_tag($data){

			$matches = '';
			# ending tags
			if (preg_match("/^\/([a-z0-9]+)/si", $data, $matches)){
				$name = StrToLower($matches[1]);
				if (in_array($name, array_keys($this->allowed))){
					if (!in_array($name, $this->no_close)){
						if ($this->tag_counts[$name]){
							$this->tag_counts[$name]--;
							return '</'.$name.'>';
						}
					}
				}else{
					return '';
				}
			}

			# starting tags
			if (preg_match("/^([a-z0-9]+)(.*?)(\/?)$/si", $data, $matches)){
				$name = StrToLower($matches[1]);
				$body = $matches[2];
				$ending = $matches[3];
				if (in_array($name, array_keys($this->allowed))){
					$params = "";
					$matches_2 = '';
					$matches_1 = '';
					preg_match_all("/([a-z0-9]+)=\"(.*?)\"/si", $body, $matches_2, PREG_SET_ORDER);
					preg_match_all("/([a-z0-9]+)=([^\"\s]+)/si", $body, $matches_1, PREG_SET_ORDER);
					$matches = array_merge($matches_1, $matches_2);
					foreach($matches as $match){
						$pname = StrToLower($match[1]);
						if (in_array($pname, $this->allowed[$name])){
							$value = $match[2];
							if (in_array($pname, $this->protocol_attributes)){
								$value = $this->process_param_protocol($value);
							}
							$params .= " $pname=\"$value\"";
						}
					}
					if (in_array($name, $this->no_close)){
						$ending = ' /';
					}
					if (in_array($name, $this->always_close)){
						$ending = '';
					}
					if (!$ending){
						if (isset($this->tag_counts[$name])){
							$this->tag_counts[$name]++;
						}else{
							$this->tag_counts[$name] = 1;
						}
					}
					if ($ending){
						$ending = ' /';
					}
					return '<'.$name.$params.$ending.'>';
				}else{
					return '';
				}
			}

			# comments
			if (preg_match("/^!--(.*)--$/si", $data)){
				if ($this->strip_comments){
					return '';
				}else{
					return '<'.$data.'>';
				}
			}


			# garbage, ignore it
			return '';
		}

		###############################################################

		function process_param_protocol($data){
			$matches = '';
			if (preg_match("/^([^:]+)\:/si", $data, $matches)){
				if (!in_array($matches[1], $this->allowed_protocols)){
					$data = '#'.substr($data, strlen($matches[1])+1);
				}
			}

			return $data;
		}

		###############################################################

		function process_remove_blanks($data){
			foreach($this->remove_blanks as $tag){

				$data = preg_replace("/<{$tag}(\s[^>]*)?><\\/{$tag}>/", '', $data);
				$data = preg_replace("/<{$tag}(\s[^>]*)?\\/>/", '', $data);
			}
			return $data;
		}

		###############################################################

		function fix_case($data){

			$data_notags = Strip_Tags($data);
			$data_notags = preg_replace('/[^a-zA-Z]/', '', $data_notags);

			if (strlen($data_notags)<5){
				return $data;
			}

			if (preg_match('/[a-z]/', $data_notags)){
				return $data;
			}

			return preg_replace(
				"/(>|^)([^<]+?)(<|$)/se",
					"StripSlashes('\\1').".
					"\$this->fix_case_inner(StripSlashes('\\2')).".
					"StripSlashes('\\3')",
				$data
			);
		}

		function fix_case_inner($data){

			$data = StrToLower($data);

			$data = preg_replace('/(^|[^\w\s])(\s*)([a-z])/e',"StripSlashes('\\1\\2').StrToUpper(StripSlashes('\\3'))", $data);

			return $data;
		}

		###############################################################

	}

?>