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December 4, 2008 16:49
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require 'cgi' | |
require 'html5/tokenizer' | |
module HTML5 | |
# This module provides sanitization of XHTML+MathML+SVG | |
# and of inline style attributes. | |
# | |
# It can be either at the Tokenizer stage: | |
# | |
# HTMLParser.parse(html, :tokenizer => HTMLSanitizer) | |
# | |
# or, if you already have a parse tree (in this example, a REXML tree), | |
# at the Serializer stage: | |
# | |
# tokens = TreeWalkers.get_tree_walker('rexml').new(tree) | |
# HTMLSerializer.serialize(tokens, {:encoding=>'utf-8', | |
# :sanitize => true}) | |
module HTMLSanitizeModule | |
ACCEPTABLE_ELEMENTS = %w[a abbr acronym address area b big blockquote br | |
button caption center cite code col colgroup dd del dfn dir div dl dt | |
em fieldset font form h1 h2 h3 h4 h5 h6 hr i img input ins kbd label | |
legend li map menu ol optgroup option p pre q s samp select small span | |
strike strong sub sup table tbody td textarea tfoot th thead tr tt u | |
ul var] | |
MATHML_ELEMENTS = %w[maction math merror mfrac mi mmultiscripts mn mo | |
mover mpadded mphantom mprescripts mroot mrow mspace msqrt mstyle msub | |
msubsup msup mtable mtd mtext mtr munder munderover none] | |
SVG_ELEMENTS = %w[a animate animateColor animateMotion animateTransform | |
circle defs desc ellipse font-face font-face-name font-face-src g | |
glyph hkern image linearGradient line marker metadata missing-glyph | |
mpath path polygon polyline radialGradient rect set stop svg switch | |
text title tspan use] | |
ACCEPTABLE_ATTRIBUTES = %w[abbr accept accept-charset accesskey action | |
align alt axis border cellpadding cellspacing char charoff charset | |
checked cite class clear cols colspan color compact coords datetime | |
dir disabled enctype for frame headers height href hreflang hspace id | |
ismap label lang longdesc maxlength media method multiple name nohref | |
noshade nowrap prompt readonly rel rev rows rowspan rules scope | |
selected shape size span src start style summary tabindex target title | |
type usemap valign value vspace width xml:lang] | |
MATHML_ATTRIBUTES = %w[actiontype align columnalign columnalign | |
columnalign columnlines columnspacing columnspan depth display | |
displaystyle equalcolumns equalrows fence fontstyle fontweight frame | |
height linethickness lspace mathbackground mathcolor mathvariant | |
mathvariant maxsize minsize other rowalign rowalign rowalign rowlines | |
rowspacing rowspan rspace scriptlevel selection separator stretchy | |
width width xlink:href xlink:show xlink:type xmlns xmlns:xlink] | |
SVG_ATTRIBUTES = %w[accent-height accumulate additive alphabetic | |
arabic-form ascent attributeName attributeType baseProfile bbox begin | |
by calcMode cap-height class color color-rendering content cx cy d dx | |
dy descent display dur end fill fill-rule font-family font-size | |
font-stretch font-style font-variant font-weight from fx fy g1 g2 | |
glyph-name gradientUnits hanging height horiz-adv-x horiz-origin-x id | |
ideographic k keyPoints keySplines keyTimes lang marker-end | |
marker-mid marker-start markerHeight markerUnits markerWidth | |
mathematical max min name offset opacity orient origin | |
overline-position overline-thickness panose-1 path pathLength points | |
preserveAspectRatio r refX refY repeatCount repeatDur | |
requiredExtensions requiredFeatures restart rotate rx ry slope stemh | |
stemv stop-color stop-opacity strikethrough-position | |
strikethrough-thickness stroke stroke-dasharray stroke-dashoffset | |
stroke-linecap stroke-linejoin stroke-miterlimit stroke-opacity | |
stroke-width systemLanguage target text-anchor to transform type u1 | |
u2 underline-position underline-thickness unicode unicode-range | |
units-per-em values version viewBox visibility width widths x | |
x-height x1 x2 xlink:actuate xlink:arcrole xlink:href xlink:role | |
xlink:show xlink:title xlink:type xml:base xml:lang xml:space xmlns | |
xmlns:xlink y y1 y2 zoomAndPan] | |
ATTR_VAL_IS_URI = %w[href src cite action longdesc xlink:href xml:base] | |
ACCEPTABLE_CSS_PROPERTIES = %w[azimuth background-color | |
border-bottom-color border-collapse border-color border-left-color | |
border-right-color border-top-color clear color cursor direction | |
display elevation float font font-family font-size font-style | |
font-variant font-weight height letter-spacing line-height overflow | |
pause pause-after pause-before pitch pitch-range richness speak | |
speak-header speak-numeral speak-punctuation speech-rate stress | |
text-align text-decoration text-indent unicode-bidi vertical-align | |
voice-family volume white-space width] | |
ACCEPTABLE_CSS_KEYWORDS = %w[auto aqua black block blue bold both bottom | |
brown center collapse dashed dotted fuchsia gray green !important | |
italic left lime maroon medium none navy normal nowrap olive pointer | |
purple red right solid silver teal top transparent underline white | |
yellow] | |
ACCEPTABLE_SVG_PROPERTIES = %w[fill fill-opacity fill-rule stroke | |
stroke-width stroke-linecap stroke-linejoin stroke-opacity] | |
ACCEPTABLE_PROTOCOLS = %w[ed2k ftp http https irc mailto news gopher nntp | |
telnet webcal xmpp callto feed urn aim rsync tag ssh sftp rtsp afs] | |
# subclasses may define their own versions of these constants | |
ALLOWED_ELEMENTS = ACCEPTABLE_ELEMENTS + MATHML_ELEMENTS + SVG_ELEMENTS | |
ALLOWED_ATTRIBUTES = ACCEPTABLE_ATTRIBUTES + MATHML_ATTRIBUTES + SVG_ATTRIBUTES | |
ALLOWED_CSS_PROPERTIES = ACCEPTABLE_CSS_PROPERTIES | |
ALLOWED_CSS_KEYWORDS = ACCEPTABLE_CSS_KEYWORDS | |
ALLOWED_SVG_PROPERTIES = ACCEPTABLE_SVG_PROPERTIES | |
ALLOWED_PROTOCOLS = ACCEPTABLE_PROTOCOLS | |
def sanitize_token(token) | |
case token[:type] | |
when :StartTag, :EndTag, :EmptyTag | |
if self.class.const_get("ALLOWED_ELEMENTS").include?(token[:name]) | |
if token.has_key? :data | |
attrs = Hash[*token[:data].flatten] | |
attrs.delete_if { |attr,v| !self.class.const_get("ALLOWED_ATTRIBUTES").include?(attr) } | |
ATTR_VAL_IS_URI.each do |attr| | |
val_unescaped = CGI.unescapeHTML(attrs[attr].to_s).gsub(/`|[\000-\040\177\s]+|\302[\200-\240]/,'').downcase | |
if val_unescaped =~ /^[a-z0-9][-+.a-z0-9]*:/ and !self.class.const_get("ALLOWED_PROTOCOLS").include?(val_unescaped.split(':')[0]) | |
attrs.delete attr | |
end | |
end | |
if attrs['style'] | |
attrs['style'] = sanitize_css(attrs['style']) | |
end | |
token[:data] = attrs.map {|k,v| [k,v]} | |
end | |
return token | |
else | |
if token[:type] == :EndTag | |
token[:data] = "</#{token[:name]}>" | |
elsif token[:data] | |
attrs = token[:data].map {|k,v| " #{k}=\"#{CGI.escapeHTML(v)}\""}.join('') | |
token[:data] = "<#{token[:name]}#{attrs}>" | |
else | |
token[:data] = "<#{token[:name]}>" | |
end | |
token[:data].insert(-2,'/') if token[:type] == :EmptyTag | |
token[:type] = :Characters | |
token.delete(:name) | |
return token | |
end | |
when :Comment | |
token[:data] = "" | |
return token | |
else | |
return token | |
end | |
end | |
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 self.class.const_get("ALLOWED_CSS_PROPERTIES").include?(prop) | |
clean << "#{prop}: #{val};" | |
elsif %w[background border margin padding].include?(prop.split('-')[0]) | |
clean << "#{prop}: #{val};" unless val.split().any? do |keyword| | |
!self.class.const_get("ALLOWED_CSS_KEYWORDS").include?(keyword) 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 self.class.const_get("ALLOWED_SVG_PROPERTIES").include?(prop) | |
clean << "#{prop}: #{val};" | |
end | |
end | |
style = clean.join(' ') | |
end | |
end | |
class HTMLSanitizer < HTMLTokenizer | |
include HTMLSanitizeModule | |
def each | |
super do |token| | |
yield(sanitize_token(token)) | |
end | |
end | |
end | |
end |
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