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, fragment = true) ⇒ SaxFilter

Returns a new instance of SaxFilter.



36
37
38
39
40
41
42
43
44
45
 
# File 'lib/antisamy/html/sax_filter.rb', line 36

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

Instance Method Details

#cdata_block(text) ⇒ Object

Add cdata a cdata block



295
296
297
298
299
300
301
302
303
 
# File 'lib/antisamy/html/sax_filter.rb', line 295

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



248
249
250
251
252
253
254
255
256
257
 
# File 'lib/antisamy/html/sax_filter.rb', line 248

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



58
59
60
61
62
63
64
65
66
 
# File 'lib/antisamy/html/sax_filter.rb', line 58

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 



68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
 
# File 'lib/antisamy/html/sax_filter.rb', line 68

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



260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
 
# File 'lib/antisamy/html/sax_filter.rb', line 260

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 



243
244
245
 
# File 'lib/antisamy/html/sax_filter.rb', line 243

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

#error(text) ⇒ Object 



47
48
 
# File 'lib/antisamy/html/sax_filter.rb', line 47

def error(text)
end

#fetch_attribute(array, key) ⇒ Object 



84
85
86
87
88
89
90
91
 
# File 'lib/antisamy/html/sax_filter.rb', line 84

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



54
55
 
# File 'lib/antisamy/html/sax_filter.rb', line 54

def start_document
end

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

Start an element,



94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
 
# File 'lib/antisamy/html/sax_filter.rb', line 94

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
    if @fragment
			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
		end
		if name.eql?("head") && @fragment
      @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::ANCHORS_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 



239
240
241
 
# File 'lib/antisamy/html/sax_filter.rb', line 239

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

#warning(text) ⇒ Object 



50
51
 
# File 'lib/antisamy/html/sax_filter.rb', line 50

def warning(text)
end