254 lines
7.6 KiB
Go
254 lines
7.6 KiB
Go
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// Copyright (c) 2014, David Kitchen <david@buro9.com>
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice, this
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// list of conditions and the following disclaimer.
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//
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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//
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// * Neither the name of the organisation (Microcosm) nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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package bluemonday
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import (
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"regexp"
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)
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// StrictPolicy returns an empty policy, which will effectively strip all HTML
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// elements and their attributes from a document.
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func StrictPolicy() *Policy {
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return NewPolicy()
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}
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// StripTagsPolicy is DEPRECATED. Use StrictPolicy instead.
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func StripTagsPolicy() *Policy {
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return StrictPolicy()
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}
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// UGCPolicy returns a policy aimed at user generated content that is a result
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// of HTML WYSIWYG tools and Markdown conversions.
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//
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// This is expected to be a fairly rich document where as much markup as
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// possible should be retained. Markdown permits raw HTML so we are basically
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// providing a policy to sanitise HTML5 documents safely but with the
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// least intrusion on the formatting expectations of the user.
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func UGCPolicy() *Policy {
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p := NewPolicy()
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///////////////////////
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// Global attributes //
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///////////////////////
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// "class" is not permitted as we are not allowing users to style their own
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// content
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p.AllowStandardAttributes()
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//////////////////////////////
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// Global URL format policy //
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//////////////////////////////
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p.AllowStandardURLs()
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////////////////////////////////
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// Declarations and structure //
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////////////////////////////////
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// "xml" "xslt" "DOCTYPE" "html" "head" are not permitted as we are
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// expecting user generated content to be a fragment of HTML and not a full
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// document.
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//////////////////////////
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// Sectioning root tags //
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//////////////////////////
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// "article" and "aside" are permitted and takes no attributes
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p.AllowElements("article", "aside")
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// "body" is not permitted as we are expecting user generated content to be a fragment
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// of HTML and not a full document.
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// "details" is permitted, including the "open" attribute which can either
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// be blank or the value "open".
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p.AllowAttrs(
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"open",
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).Matching(regexp.MustCompile(`(?i)^(|open)$`)).OnElements("details")
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// "fieldset" is not permitted as we are not allowing forms to be created.
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// "figure" is permitted and takes no attributes
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p.AllowElements("figure")
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// "nav" is not permitted as it is assumed that the site (and not the user)
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// has defined navigation elements
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// "section" is permitted and takes no attributes
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p.AllowElements("section")
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// "summary" is permitted and takes no attributes
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p.AllowElements("summary")
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//////////////////////////
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// Headings and footers //
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//////////////////////////
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// "footer" is not permitted as we expect user content to be a fragment and
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// not structural to this extent
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// "h1" through "h6" are permitted and take no attributes
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p.AllowElements("h1", "h2", "h3", "h4", "h5", "h6")
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// "header" is not permitted as we expect user content to be a fragment and
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// not structural to this extent
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// "hgroup" is permitted and takes no attributes
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p.AllowElements("hgroup")
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/////////////////////////////////////
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// Content grouping and separating //
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/////////////////////////////////////
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// "blockquote" is permitted, including the "cite" attribute which must be
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// a standard URL.
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p.AllowAttrs("cite").OnElements("blockquote")
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// "br" "div" "hr" "p" "span" "wbr" are permitted and take no attributes
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p.AllowElements("br", "div", "hr", "p", "span", "wbr")
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///////////
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// Links //
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///////////
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// "a" is permitted
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p.AllowAttrs("href").OnElements("a")
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// "area" is permitted along with the attributes that map image maps work
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p.AllowAttrs("name").Matching(
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regexp.MustCompile(`^([\p{L}\p{N}_-]+)$`),
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).OnElements("map")
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p.AllowAttrs("alt").Matching(Paragraph).OnElements("area")
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p.AllowAttrs("coords").Matching(
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regexp.MustCompile(`^([0-9]+,)+[0-9]+$`),
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).OnElements("area")
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p.AllowAttrs("href").OnElements("area")
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p.AllowAttrs("rel").Matching(SpaceSeparatedTokens).OnElements("area")
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p.AllowAttrs("shape").Matching(
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regexp.MustCompile(`(?i)^(default|circle|rect|poly)$`),
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).OnElements("area")
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p.AllowAttrs("usemap").Matching(
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regexp.MustCompile(`(?i)^#[\p{L}\p{N}_-]+$`),
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).OnElements("img")
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// "link" is not permitted
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/////////////////////
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// Phrase elements //
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/////////////////////
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// The following are all inline phrasing elements
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p.AllowElements("abbr", "acronym", "cite", "code", "dfn", "em",
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"figcaption", "mark", "s", "samp", "strong", "sub", "sup", "var")
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// "q" is permitted and "cite" is a URL and handled by URL policies
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p.AllowAttrs("cite").OnElements("q")
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// "time" is permitted
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p.AllowAttrs("datetime").Matching(ISO8601).OnElements("time")
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////////////////////
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// Style elements //
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////////////////////
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// block and inline elements that impart no semantic meaning but style the
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// document
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p.AllowElements("b", "i", "pre", "small", "strike", "tt", "u")
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// "style" is not permitted as we are not yet sanitising CSS and it is an
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// XSS attack vector
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//////////////////////
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// HTML5 Formatting //
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//////////////////////
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// "bdi" "bdo" are permitted
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p.AllowAttrs("dir").Matching(Direction).OnElements("bdi", "bdo")
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// "rp" "rt" "ruby" are permitted
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p.AllowElements("rp", "rt", "ruby")
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///////////////////////////
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// HTML5 Change tracking //
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///////////////////////////
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// "del" "ins" are permitted
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p.AllowAttrs("cite").Matching(Paragraph).OnElements("del", "ins")
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p.AllowAttrs("datetime").Matching(ISO8601).OnElements("del", "ins")
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///////////
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// Lists //
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///////////
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p.AllowLists()
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////////////
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// Tables //
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////////////
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p.AllowTables()
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///////////
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// Forms //
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///////////
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// By and large, forms are not permitted. However there are some form
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// elements that can be used to present data, and we do permit those
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//
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// "button" "fieldset" "input" "keygen" "label" "output" "select" "datalist"
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// "textarea" "optgroup" "option" are all not permitted
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// "meter" is permitted
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p.AllowAttrs(
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"value",
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"min",
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"max",
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"low",
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"high",
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"optimum",
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).Matching(Number).OnElements("meter")
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// "progress" is permitted
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p.AllowAttrs("value", "max").Matching(Number).OnElements("progress")
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//////////////////////
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// Embedded content //
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//////////////////////
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// Vast majority not permitted
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// "audio" "canvas" "embed" "iframe" "object" "param" "source" "svg" "track"
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// "video" are all not permitted
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p.AllowImages()
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return p
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}
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