Class: AntiSamy::SaxFilter

Inherits:
Nokogiri::XML::SAX::Document
  • Object
show all
Defined in:
lib/antisamy/html/sax_filter.rb

Instance Method Summary collapse

Constructor Details

#initialize(policy, handler, param_tag) ⇒ SaxFilter

Returns a new instance of SaxFilter.



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# File 'lib/antisamy/html/sax_filter.rb', line 36

def initialize(policy,handler,param_tag)
  @policy = policy
  @handler = handler
  @stack = Stack.new
  @css_content = nil
  @css_attributes = nil
  @css_scanner = CssScanner.new(policy)
  @param_tag = param_tag
end

Instance Method Details

#cdata_block(text) ⇒ Object

Add cdata a cdata block



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# File 'lib/antisamy/html/sax_filter.rb', line 292

def cdata_block(text)
  if @stack.peek?(:css)
    @css_content << text
  elsif !@stack.peek?(:remove)
    @handler.characters(text)
  else
    @handler.cdata(@handler.encode_text(text)) unless @stack.peek == :remove
  end
end

#characters(text) ⇒ Object

Add character data to the current tag



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# File 'lib/antisamy/html/sax_filter.rb', line 245

def characters(text)
  unless text =~ /\S/ # skip whitespace
    return unless @policy.directive(Policy::PRESERVE_SPACE)
  end
  if @stack.peek?(:css)
    @css_content << text
  elsif !@stack.peek?(:remove)
    @handler.characters(text)
  end
end

#comment(text) ⇒ Object

Add a comment block



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# File 'lib/antisamy/html/sax_filter.rb', line 57

def comment(text)
  return if text.nil?
  if @policy.directive(Policy::PRESERVE_COMMENTS) =~ /true/i
    # Strip out conditional directives
    text.gsub!(%r{<!?!\[(?:end)?if*\]}ixm,"")
    text.gsub!(%r{\[(?:if).*\]>},"")
    @handler.comment(text)
  end
end

#convert_array(x) ⇒ Object 



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# File 'lib/antisamy/html/sax_filter.rb', line 67

def convert_array(x)
  if x and x.first.is_a?(Array)
    return x
  end
  i = 0
  h = []
  while i < x.size
    m = []
    m[0] = x[i]
    m[1] = x[i+1]
    h << m
    i += 2
  end
  h
end

#end_element(name) ⇒ Object

End an elements, will raise an error on a loose tag



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# File 'lib/antisamy/html/sax_filter.rb', line 257

def end_element(name)
  if @stack.peek?(:remove)
    @stack.pop
  elsif @stack.peek?(:filter)
    @stack.pop
  elsif @stack.peek?(:css)
    @stack.pop
    # Do css stuff here
     begin
       results = @css_scanner.scan_sheet(@css_content,@policy.max_input)
       @handler.errors << results.messages
       @handler.errors.flatten!
       unless results.clean_html.nil? or results.clean_html.empty?
         @handler.start_element(name,@css_attributes)
         @handler.characters results.clean_html
         @handler.end_element(name)
       else
         @handler.start_element(name,@css_attributes)
         @handler.characters "/* */"
         @handler.end_element(name)             
       end
     rescue Exception => e
       puts e
       @handler.errors << ScanMessage.new(ScanMessage::ERROR_CSS_TAG_MALFORMED,name,@handler.encode_text(@css_content))
     ensure
       @css_content = nil
       @css_attributes = nil
     end
  else
    @stack.pop
    @handler.end_element(name)
  end
end

#end_element_namespace(name, prefix, uri) ⇒ Object 



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# File 'lib/antisamy/html/sax_filter.rb', line 240

def end_element_namespace(name,prefix,uri)
  end_element(name)
end

#error(text) ⇒ Object 



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# File 'lib/antisamy/html/sax_filter.rb', line 46

def error(text)
end

#fetch_attribute(array, key) ⇒ Object 



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# File 'lib/antisamy/html/sax_filter.rb', line 83

def fetch_attribute(array,key)
  array.each do |pair|
    if pair.first.eql?(key)
      return pair.last
    end
  end
  nil
end

#start_document ⇒ Object

Always create a HTML document unless the DECL was set beforehand



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# File 'lib/antisamy/html/sax_filter.rb', line 53

def start_document
end

#start_element(name, attributes = []) ⇒ Object

Start an element,



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# File 'lib/antisamy/html/sax_filter.rb', line 93

def start_element(name, attributes = [])
  attributes = convert_array(attributes)
  o_attributes = attributes.dup
  tag = @policy.tag(name)
  masquerade = false
  embed_name = nil
  embed_value = nil
  # Handle validate param tag as an embed tag
  if tag.nil? && @policy.directive(Policy::VALIDATE_P_AS_E) && name.eql?("param")
    embed = @param_tag
    if @policy.tag("embed")
      embed = @policy.tag("embed")
    end
    if embed and embed.action == Policy::ACTION_VALIDATE
      tag = embed
      masquerade = true
      embed_name = fetch_attribute(attributes,"name")
      embed_value = fetch_attribute(attributes,"value")
      attributes = [ [embed_name,embed_value] ]
    end
  end
  valid_attributes = []
  if @stack.peek?(:css) or @stack.peek?(:remove)
    # We are in remove mode to remove this tag as well as any child style elements if css mode
    @stack.push(:remove)
  elsif (tag.nil? && @policy.directive(Policy::ON_UNKNOWN_TAG).eql?("encode")) or (!tag.nil? && tag.action.eql?(Policy::ACTION_ENCODE)) or @policy.encode?(name.downcase)
    tmp = "<#{name}>"
    @handler.characters(tmp)
    @stack.push(:filter)
  elsif tag.nil?
    # We ignore missing HTML and BODY tags since we are fragment parsing, but the 
    # Nokogiri HTML::SAX parser injects HTML/BODY if they are missing
    unless name.eql?("html") or name.eql?("body")
      @handler.errors << ScanMessage.new(ScanMessage::ERROR_TAG_NOT_IN_POLICY,name)
    end
    # Nokogiri work around for a style tag being auto inserted inot head
    if name.eql?("head")
      @stack.push(:remove)
    else
      @stack.push(:filter)
    end
  elsif tag.action.eql?(Policy::ACTION_FILTER)
    @handler.errors << ScanMessage.new(ScanMessage::ERROR_TAG_FILTERED,name)
    @stack.push(:filter)
  elsif tag.action.eql?(Policy::ACTION_VALIDATE)
    # Handle validation
    remove_tag = false
    filter_tag = false
    is_style = name.include?("style")
    if is_style
      @stack.push(:css)
      @css_content = ''
      @css_attributes = []
    else
      # Validate attributes
      attributes.each do |pair|
        a_name = pair.first
        a_value = pair.last
        attrib = tag.attribute(a_name.downcase)
        if attrib.nil?
          attrib = @policy.global(a_name.downcase)
        end
        # check if the attribute is a style
        if a_name.eql?("style")
          # Handle Style tags
           begin
             results = @css_scanner.scan_inline(a_value,name,@policy.max_input)
             unless result.clean_html.empty?
               valid_attributes << [a_name,results.clean_html]
             end
             @handler.errors << results.messages
             @handler.errors.flatten!
           rescue Exception => e
             @handler.errors << ScanMessage.new(ScanMessage::ERROR_CSS_ATTRIBUTE_MALFORMED,name,@handler.encode_text(a_value))
           end
        elsif !attrib.nil? # Attribute is not nil lets check it
          valid = false
          attrib.values.each do |av|
            if av.eql?(a_value)
              valid_attributes << [a_name,a_value]
              valid = true
              break
            end
          end
          unless valid
            attrib.expressions.each do |ae|
              mc = ae.match(a_value)
              if mc and mc.to_s == a_value
                valid_attributes << [a_name,a_value]
                valid = true
                break
              end
            end
          end
          # we check the matches
          if !valid && attrib.action.eql?(Attribute::ACTION_REMOVE_TAG)
            @handler.errors << ScanMessage.new(ScanMessage::ERROR_ATTRIBUTE_INVALID_REMOVED,tag.name,@handler.encode_text(a_name),@handler.encode_text(a_value))
            remove_tag = true
          elsif !valid && attrib.action.eql?(Attribute::ACTION_FILTER_TAG)
            @handler.errors << ScanMessage.new(ScanMessage::ERROR_ATTRIBUTE_CAUSE_FILTER,tag.name,@handler.encode_text(a_name),@handler.encode_text(a_value))
            filter_tag = true
          elsif !valid
            @handler.errors << ScanMessage.new(ScanMessage::ERROR_ATTRIBUTE_INVALID,tag.name,@handler.encode_text(a_name),@handler.encode_text(a_value))
          end

        else # attribute was null
          @handler.errors << ScanMessage.new(ScanMessage::ERROR_ATTRIBUTE_NOT_IN_POLICY,tag.name,a_name,@handler.encode_text(a_value))
          if masquerade
            filter_tag = true
          end
        end
      end # end attirubte loop
    end
    if remove_tag
      @stack.push(:remove)
    elsif filter_tag
      @stack.push(:filter)
    else
      if name.eql?("a") and @policy.directive(Policy::ANCHROS_NOFOLLOW)
        valid_attributes << ["rel","nofollow"]
      end
      if masquerade
        valid_attributes = []
        valid_attributes << ["name",embed_name]
        valid_attributes << ["value",embed_value]
      end
      @stack.push(:keep) unless @stack.peek?(:css)
    end
    # End validation action
  elsif tag.action.eql?(Policy::ACTION_TRUNCATE)
    @stack.push(:truncate)
  else
    @handler.errors << ScanMessage.new(ScanMessage::ERROR_TAG_DISALLOWED,name)
    @stack.push(:remove)
  end
  # We now know wether to keep or truncat this tag
  if @stack.peek?(:truncate)
    @handler.start_element(name,[])
  elsif @stack.peek?(:keep)
    @handler.start_element(name,valid_attributes)
  end
end

#start_element_namespace(name, attrs = [], prefix = nil, uri = nil, ns = nil) ⇒ Object 



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# File 'lib/antisamy/html/sax_filter.rb', line 236

def start_element_namespace(name,attrs=[],prefix = nil, uri = nil, ns = nil)
  start_element(name,attrs)
end

#warning(text) ⇒ Object 



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# File 'lib/antisamy/html/sax_filter.rb', line 49

def warning(text)
end