Untitled

module HtmlHelpers 
	
	#
	# $Id: sanitize.rb 3 2005-04-05 12:51:14Z dwight $
	#
	# Copyright (c) 2005 Dwight Shih
	# A derived work of the Perl version:
	# Copyright (c) 2002 Brad Choate, bradchoate.com
	# 
	# Permission is hereby granted, free of charge, to
	# any person obtaining a copy of this software and
	# associated documentation files (the "Software"), to
	# deal in the Software without restriction, including
	# without limitation the rights to use, copy, modify,
	# merge, publish, distribute, sublicense, and/or sell
	# copies of the Software, and to permit persons to
	# whom the Software is furnished to do so, subject to
	# the following conditions:
	# 
	# The above copyright notice and this permission
	# notice shall be included in all copies or
	# substantial portions of the Software.
	# 
	# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY
	# OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
	# LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	# FITNESS FOR A PARTICULAR PURPOSE AND
	# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
	# COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
	# OR OTHER LIABILITY, WHETHER IN AN ACTION OF
	# CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
	# OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	# OTHER DEALINGS IN THE SOFTWARE.
	#
	
	def sanitize_html( html, okTags='a href, b, br, i, p' )
	# no closing tag necessary for these
	soloTags = ["br","hr"]
	
	# Build hash of allowed tags with allowed attributes
	tags = okTags.downcase().split(',').collect!{ |s| s.split(' ') }
	allowed = Hash.new
	tags.each do |s|
	key = s.shift
	allowed[key] = s
	end
	
	# Analyze all <> elements
	stack = Array.new
	result = html.gsub( /(<.*?>)/m ) do | element |
	if element =~ /\A<\/(\w+)/ then
	# </tag>
	tag = $1.downcase
	if allowed.include?(tag) && stack.include?(tag) then
		# If allowed and on the stack
		# Then pop down the stack
		top = stack.pop
		out = "</#{top}>"
		until top == tag do
		top = stack.pop
		out << "</#{top}>"
		end
		out
	end
	elsif element =~ /\A<(\w+)\s*\/>/
	# <tag />
	tag = $1.downcase
	if allowed.include?(tag) then
		"<#{tag} />"
	end
	elsif element =~ /\A<(\w+)/ then
	# <tag ...>
	tag = $1.downcase
	if allowed.include?(tag) then
		if ! soloTags.include?(tag) then
		stack.push(tag)
		end
		if allowed[tag].length == 0 then
		# no allowed attributes
		"<#{tag}>"
		else
		# allowed attributes?
		out = "<#{tag}"
		while ( $' =~ /(\w+)=("[^"]+")/ )
		attr = $1.downcase
		valu = $2
		if allowed[tag].include?(attr) then
		out << " #{attr}=#{valu}"
		end
		end
		out << ">"
		end
	end
	end
	end
	
	# eat up unmatched leading >
	while result.sub!(/\A([^<]*)>/m) { $1 } do end
	
	# eat up unmatched trailing <
	while result.sub!(/<([^>]*)\Z/m) { $1 } do end
	
	# clean up the stack
	if stack.length > 0 then
	result << "</#{stack.reverse.join('></')}>"
	end
	
	result
	end
end