278 lignes
7.8 KiB
Go
278 lignes
7.8 KiB
Go
package sanitize
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import (
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"bytes"
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"html/template"
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"log"
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"regexp"
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"strings"
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"github.com/microcosm-cc/bluemonday"
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md "github.com/russross/blackfriday"
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"golang.org/x/net/html"
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)
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//Some default rules, plus and minus some.
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var mdOptions = 0 |
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md.EXTENSION_AUTOLINK |
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md.EXTENSION_HARD_LINE_BREAK |
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md.EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK |
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md.EXTENSION_NO_INTRA_EMPHASIS |
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md.EXTENSION_SPACE_HEADERS |
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md.EXTENSION_STRIKETHROUGH
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var htmlFlags = 0 |
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md.HTML_USE_XHTML |
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md.HTML_SMARTYPANTS_FRACTIONS |
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md.HTML_SAFELINK |
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md.HTML_NOREFERRER_LINKS |
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md.HTML_HREF_TARGET_BLANK
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func init() {
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HtmlMdRenderer = md.HtmlRenderer(htmlFlags, "", "")
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}
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var HtmlMdRenderer md.Renderer
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// MarkdownToHTML : convert markdown to html
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// TODO: restrict certain types of markdown
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func MarkdownToHTML(markdown string) template.HTML {
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if len(markdown) >= 4 && markdown[:4] == ">" {
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markdown = ">" + markdown[4:]
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}
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markdown = strings.Replace(markdown, "\n>", "\n>", -1)
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unsafe := md.MarkdownOptions([]byte(markdown), HtmlMdRenderer, md.Options{Extensions: mdOptions})
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html := bluemonday.UGCPolicy().SanitizeBytes(unsafe)
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return template.HTML(html)
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}
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// Sanitize :
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/* Sanitize a message passed as a string according to a setted model or allowing a set of html tags and output a string
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*/
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func Sanitize(msg string, elements ...string) string {
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msg = repairHTMLTags(msg) // We repair possible broken html tags
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p := bluemonday.NewPolicy()
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if len(elements) > 0 {
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if elements[0] == "default" { // default model same as UGC without div
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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", "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(bluemonday.Paragraph).OnElements("area")
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p.AllowAttrs("coords").Matching(
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regexp.MustCompile(`^([0-9]+,)+[0-9]+$`),
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).OnElements("area")
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p.AllowAttrs("href").OnElements("area")
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p.AllowAttrs("rel").Matching(bluemonday.SpaceSeparatedTokens).OnElements("area")
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p.AllowAttrs("shape").Matching(
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regexp.MustCompile(`(?i)^(default|circle|rect|poly)$`),
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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(bluemonday.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(bluemonday.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(bluemonday.Paragraph).OnElements("del", "ins")
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p.AllowAttrs("datetime").Matching(bluemonday.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(bluemonday.Number).OnElements("meter")
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// "progress" is permitted
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p.AllowAttrs("value", "max").Matching(bluemonday.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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} else if elements[0] == "comment" {
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p.AllowElements("b", "strong", "em", "i", "u", "blockquote", "q")
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p.AllowImages()
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p.AllowStandardURLs()
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p.AllowAttrs("cite").OnElements("blockquote", "q")
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p.AllowAttrs("href").OnElements("a")
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p.AddTargetBlankToFullyQualifiedLinks(true)
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} else { // allowing set of html tags
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p.AllowElements(elements...)
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}
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}
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return p.Sanitize(msg)
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}
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/*
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* Should close any opened tags and strip any empty end tags
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*/
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func repairHTMLTags(brokenHTML string) string {
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reader := strings.NewReader(brokenHTML)
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root, err := html.Parse(reader)
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if err != nil {
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log.Fatal(err)
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}
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var b bytes.Buffer
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html.Render(&b, root)
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fixedHTML := b.String()
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return fixedHTML
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}
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