190 lines
8.5 KiB
Ruby
190 lines
8.5 KiB
Ruby
require 'cgi'
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require 'html5/tokenizer'
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module HTML5
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# This module provides sanitization of XHTML+MathML+SVG
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# and of inline style attributes.
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#
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# It can be either at the Tokenizer stage:
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#
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# HTMLParser.parse(html, :tokenizer => HTMLSanitizer)
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#
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# or, if you already have a parse tree (in this example, a REXML tree),
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# at the Serializer stage:
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#
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# tokens = TreeWalkers.get_tree_walker('rexml').new(tree)
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# HTMLSerializer.serialize(tokens, {:encoding=>'utf-8',
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# :sanitize => true})
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module HTMLSanitizeModule
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ACCEPTABLE_ELEMENTS = %w[a abbr acronym address area b big blockquote br
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button caption center cite code col colgroup dd del dfn dir div dl dt
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em fieldset font form h1 h2 h3 h4 h5 h6 hr i img input ins kbd label
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legend li map menu ol optgroup option p pre q s samp select small span
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strike strong sub sup table tbody td textarea tfoot th thead tr tt u
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ul var]
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MATHML_ELEMENTS = %w[annotation annotation-xml maction math merror mfrac
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mi mmultiscripts mn mo mover mpadded mphantom mprescripts mroot mrow
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mspace msqrt mstyle msub msubsup msup mtable mtd mtext mtr munder
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munderover none semantics]
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SVG_ELEMENTS = %w[a animate animateColor animateMotion animateTransform
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circle defs desc ellipse font-face font-face-name font-face-src g
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glyph hkern image linearGradient line marker metadata missing-glyph
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mpath path polygon polyline radialGradient rect set stop svg switch
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text title tspan use]
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ACCEPTABLE_ATTRIBUTES = %w[abbr accept accept-charset accesskey action
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align alt axis border cellpadding cellspacing char charoff charset
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checked cite class clear cols colspan color compact coords datetime
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dir disabled enctype for frame headers height href hreflang hspace id
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ismap label lang longdesc maxlength media method multiple name nohref
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noshade nowrap prompt readonly rel rev rows rowspan rules scope
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selected shape size span src start style summary tabindex target title
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type usemap valign value vspace width xml:lang]
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MATHML_ATTRIBUTES = %w[actiontype align columnalign columnalign
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columnalign columnlines columnspacing columnspan depth display
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displaystyle encoding equalcolumns equalrows fence fontstyle fontweight
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frame height linethickness lspace mathbackground mathcolor mathvariant
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mathvariant maxsize minsize other rowalign rowalign rowalign rowlines
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rowspacing rowspan rspace scriptlevel selection separator stretchy
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width width xlink:href xlink:show xlink:type xmlns xmlns:xlink]
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SVG_ATTRIBUTES = %w[accent-height accumulate additive alphabetic
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arabic-form ascent attributeName attributeType baseProfile bbox begin
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by calcMode cap-height class color color-rendering content cx cy d dx
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dy descent display dur end fill fill-rule font-family font-size
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font-stretch font-style font-variant font-weight from fx fy g1 g2
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glyph-name gradientUnits hanging height horiz-adv-x horiz-origin-x id
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ideographic k keyPoints keySplines keyTimes lang marker-end
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marker-mid marker-start markerHeight markerUnits markerWidth
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mathematical max min name offset opacity orient origin
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overline-position overline-thickness panose-1 path pathLength points
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preserveAspectRatio r refX refY repeatCount repeatDur
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requiredExtensions requiredFeatures restart rotate rx ry slope stemh
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stemv stop-color stop-opacity strikethrough-position
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strikethrough-thickness stroke stroke-dasharray stroke-dashoffset
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stroke-linecap stroke-linejoin stroke-miterlimit stroke-opacity
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stroke-width systemLanguage target text-anchor to transform type u1
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u2 underline-position underline-thickness unicode unicode-range
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units-per-em values version viewBox visibility width widths x
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x-height x1 x2 xlink:actuate xlink:arcrole xlink:href xlink:role
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xlink:show xlink:title xlink:type xml:base xml:lang xml:space xmlns
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xmlns:xlink y y1 y2 zoomAndPan]
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ATTR_VAL_IS_URI = %w[href src cite action longdesc xlink:href xml:base]
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ACCEPTABLE_CSS_PROPERTIES = %w[azimuth background-color
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border-bottom-color border-collapse border-color border-left-color
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border-right-color border-top-color clear color cursor direction
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display elevation float font font-family font-size font-style
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font-variant font-weight height letter-spacing line-height overflow
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pause pause-after pause-before pitch pitch-range richness speak
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speak-header speak-numeral speak-punctuation speech-rate stress
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text-align text-decoration text-indent unicode-bidi vertical-align
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voice-family volume white-space width]
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ACCEPTABLE_CSS_KEYWORDS = %w[auto aqua black block blue bold both bottom
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brown center collapse dashed dotted fuchsia gray green !important
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italic left lime maroon medium none navy normal nowrap olive pointer
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purple red right solid silver teal top transparent underline white
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yellow]
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ACCEPTABLE_SVG_PROPERTIES = %w[fill fill-opacity fill-rule stroke
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stroke-width stroke-linecap stroke-linejoin stroke-opacity]
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ACCEPTABLE_PROTOCOLS = %w[ed2k ftp http https irc mailto news gopher nntp
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telnet webcal xmpp callto feed urn aim rsync tag ssh sftp rtsp afs]
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# subclasses may define their own versions of these constants
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ALLOWED_ELEMENTS = ACCEPTABLE_ELEMENTS + MATHML_ELEMENTS + SVG_ELEMENTS
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ALLOWED_ATTRIBUTES = ACCEPTABLE_ATTRIBUTES + MATHML_ATTRIBUTES + SVG_ATTRIBUTES
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ALLOWED_CSS_PROPERTIES = ACCEPTABLE_CSS_PROPERTIES
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ALLOWED_CSS_KEYWORDS = ACCEPTABLE_CSS_KEYWORDS
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ALLOWED_SVG_PROPERTIES = ACCEPTABLE_SVG_PROPERTIES
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ALLOWED_PROTOCOLS = ACCEPTABLE_PROTOCOLS
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def sanitize_token(token)
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case token[:type]
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when :StartTag, :EndTag, :EmptyTag
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if self.class.const_get("ALLOWED_ELEMENTS").include?(token[:name])
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if token.has_key? :data
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attrs = Hash[*token[:data].flatten]
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attrs.delete_if { |attr,v| !self.class.const_get("ALLOWED_ATTRIBUTES").include?(attr) }
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ATTR_VAL_IS_URI.each do |attr|
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val_unescaped = CGI.unescapeHTML(attrs[attr].to_s).gsub(/`|[\000-\040\177\s]+|\302[\200-\240]/,'').downcase
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if val_unescaped =~ /^[a-z0-9][-+.a-z0-9]*:/ and !self.class.const_get("ALLOWED_PROTOCOLS").include?(val_unescaped.split(':')[0])
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attrs.delete attr
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end
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end
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if attrs['style']
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attrs['style'] = sanitize_css(attrs['style'])
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end
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token[:data] = attrs.map {|k,v| [k,v]}
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end
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return token
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else
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if token[:type] == :EndTag
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token[:data] = "</#{token[:name]}>"
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elsif token[:data]
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attrs = token[:data].map {|k,v| " #{k}=\"#{CGI.escapeHTML(v)}\""}.join('')
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token[:data] = "<#{token[:name]}#{attrs}>"
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else
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token[:data] = "<#{token[:name]}>"
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end
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token[:data].insert(-2,'/') if token[:type] == :EmptyTag
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token[:type] = :Characters
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token.delete(:name)
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return token
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end
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when :Comment
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token[:data] = ""
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return token
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else
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return token
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end
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end
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def sanitize_css(style)
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# disallow urls
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style = style.to_s.gsub(/url\s*\(\s*[^\s)]+?\s*\)\s*/, ' ')
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# gauntlet
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return '' unless style =~ /^([:,;#%.\sa-zA-Z0-9!]|\w-\w|\'[\s\w]+\'|\"[\s\w]+\"|\([\d,\s]+\))*$/
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return '' unless style =~ /^(\s*[-\w]+\s*:\s*[^:;]*(;|$))*$/
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clean = []
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style.scan(/([-\w]+)\s*:\s*([^:;]*)/) do |prop, val|
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next if val.empty?
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prop.downcase!
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if self.class.const_get("ALLOWED_CSS_PROPERTIES").include?(prop)
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clean << "#{prop}: #{val};"
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elsif %w[background border margin padding].include?(prop.split('-')[0])
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clean << "#{prop}: #{val};" unless val.split().any? do |keyword|
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!self.class.const_get("ALLOWED_CSS_KEYWORDS").include?(keyword) and
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keyword !~ /^(#[0-9a-f]+|rgb\(\d+%?,\d*%?,?\d*%?\)?|\d{0,2}\.?\d{0,2}(cm|em|ex|in|mm|pc|pt|px|%|,|\))?)$/
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end
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elsif self.class.const_get("ALLOWED_SVG_PROPERTIES").include?(prop)
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clean << "#{prop}: #{val};"
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end
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end
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style = clean.join(' ')
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end
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end
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class HTMLSanitizer < HTMLTokenizer
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include HTMLSanitizeModule
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def each
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super do |token|
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yield(sanitize_token(token))
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end
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end
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end
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end
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