require 'rubygems' gem 'nokogiri', '>=1.0.5' require 'nokogiri' require 'cgi' require "dryopteris/whitelist" module Dryopteris class << self def strip_tags(string_or_io, encoding=nil) return nil if string_or_io.nil? return "" if string_or_io.strip.size == 0 doc = Nokogiri::HTML.parse(string_or_io, nil, encoding) body_element = doc.at("/html/body") return "" if body_element.nil? body_element.inner_text end def sanitize(string, encoding=nil) return nil if string.nil? return "" if string.strip.size == 0 string = "" + string + "" doc = Nokogiri::HTML.parse(string, nil, encoding) body = doc.xpath("/html/body").first return "" if body.nil? body.children.each do |node| traverse_conditionally_top_down(node, :sanitize_node) end body.children.map { |x| x.to_xml }.join end def sanitize_document(string_or_io, encoding=nil) return nil if string_or_io.nil? return "" if string_or_io.strip.size == 0 doc = Nokogiri::HTML.parse(string_or_io, nil, encoding) elements = doc.xpath("/html/head/*","/html/body/*") return "" if (elements.nil? || elements.empty?) elements.each do |node| traverse_conditionally_top_down(node, :sanitize_node) end doc.root.to_xml end private def traverse_conditionally_top_down(node, method_name) return if send(method_name, node) node.children.each {|j| traverse_conditionally_top_down(j, method_name)} end def remove_tags_from_node(node) replacement_killer = Nokogiri::XML::Text.new(node.text, node.document) node.add_next_sibling(replacement_killer) node.remove return true end def sanitize_node(node) case node.type when 1 # Nokogiri::XML::Node::ELEMENT_NODE if HashedWhiteList::ALLOWED_ELEMENTS[node.name] node.attributes.each do |attr| node.remove_attribute(attr.first) unless HashedWhiteList::ALLOWED_ATTRIBUTES[attr.first] end node.attributes.each do |attr| if HashedWhiteList::ATTR_VAL_IS_URI[attr.first] # this block lifted nearly verbatim from HTML5 sanitization val_unescaped = CGI.unescapeHTML(attr.last.to_s).gsub(/`|[\000-\040\177\s]+|\302[\200-\240]/,'').downcase if val_unescaped =~ /^[a-z0-9][-+.a-z0-9]*:/ and HashedWhiteList::ALLOWED_PROTOCOLS[val_unescaped.split(':')[0]].nil? node.remove_attribute(attr.first) end end end if node.attributes['style'] node['style'] = sanitize_css(node.attributes['style']) end return false end when 3 # Nokogiri::XML::Node::TEXT_NODE return false when 4 # Nokogiri::XML::Node::CDATA_SECTION_NODE return false end replacement_killer = Nokogiri::XML::Text.new(node.to_s, node.document) node.add_next_sibling(replacement_killer) node.remove return true end # this liftend nearly verbatim from html5 def sanitize_css(style) # disallow urls style = style.to_s.gsub(/url\s*$\s*[^\s)]+?\s*$\s*/, ' ') # gauntlet return '' unless style =~ /^([:,;#%.\sa-zA-Z0-9!]|\w-\w|\'[\s\w]+\'|\"[\s\w]+\"|$[\d,\s]+$)*$/ return '' unless style =~ /^\s*([-\w]+\s*:[^:;]*(;\s*|$))*$/ clean = [] style.scan(/([-\w]+)\s*:\s*([^:;]*)/) do |prop, val| next if val.empty? prop.downcase! if HashedWhiteList::ALLOWED_CSS_PROPERTIES[prop] clean << "#{prop}: #{val};" elsif %w[background border margin padding].include?(prop.split('-')[0]) clean << "#{prop}: #{val};" unless val.split().any? do |keyword| HashedWhiteList::ALLOWED_CSS_KEYWORDS[keyword].nil? and keyword !~ /^(#[0-9a-f]+|rgb$\d+%?,\d*%?,?\d*%?$?|\d{0,2}\.?\d{0,2}(cm|em|ex|in|mm|pc|pt|px|%|,|\))?)$/ end elsif HashedWhiteList::ALLOWED_SVG_PROPERTIES[prop] clean << "#{prop}: #{val};" end end style = clean.join(' ') end end # self module HashedWhiteList # turn each of the whitelist arrays into a hash for faster lookup WhiteList.constants.each do |constant| next unless WhiteList.module_eval("#{constant}").is_a?(Array) module_eval <<-CODE #{constant} = {} WhiteList::#{constant}.each { |c| #{constant}[c] = true ; #{constant}[c.downcase] = true } CODE end end end