Documentation ¶
Overview ¶
Package bluemonday provides a way of describing a whitelist of HTML elements and attributes as a policy, and for that policy to be applied to untrusted strings from users that may contain markup. All elements and attributes not on the whitelist will be stripped.
The default bluemonday.UGCPolicy().Sanitize() turns this:
Hello <STYLE>.XSS{background-image:url("javascript:alert('XSS')");}</STYLE><A CLASS=XSS></A>World
Into the more harmless:
Hello World
And it turns this:
<a href="javascript:alert('XSS1')" onmouseover="alert('XSS2')">XSS<a>
Into this:
XSS
Whilst still allowing this:
<a href="http://www.google.com/"> <img src="https://ssl.gstatic.com/accounts/ui/logo_2x.png"/> </a>
To pass through mostly unaltered (it gained a rel="nofollow"):
<a href="http://www.google.com/" rel="nofollow"> <img src="https://ssl.gstatic.com/accounts/ui/logo_2x.png"/> </a>
The primary purpose of bluemonday is to take potentially unsafe user generated content (from things like Markdown, HTML WYSIWYG tools, etc) and make it safe for you to put on your website.
It protects sites against XSS (http://en.wikipedia.org/wiki/Cross-site_scripting) and other malicious content that a user interface may deliver. There are many vectors for an XSS attack (https://www.owasp.org/index.php/XSS_Filter_Evasion_Cheat_Sheet) and the safest thing to do is to sanitize user input against a known safe list of HTML elements and attributes.
Note: You should always run bluemonday after any other processing.
If you use blackfriday (https://github.com/russross/blackfriday) or Pandoc (http://johnmacfarlane.net/pandoc/) then bluemonday should be run after these steps. This ensures that no insecure HTML is introduced later in your process.
bluemonday is heavily inspired by both the OWASP Java HTML Sanitizer (https://code.google.com/p/owasp-java-html-sanitizer/) and the HTML Purifier (http://htmlpurifier.org/).
We ship two default policies, one is bluemonday.StrictPolicy() and can be thought of as equivalent to stripping all HTML elements and their attributes as it has nothing on its whitelist.
The other is bluemonday.UGCPolicy() and allows a broad selection of HTML elements and attributes that are safe for user generated content. Note that this policy does not whitelist iframes, object, embed, styles, script, etc.
The essence of building a policy is to determine which HTML elements and attributes are considered safe for your scenario. OWASP provide an XSS prevention cheat sheet ( https://www.google.com/search?q=xss+prevention+cheat+sheet ) to help explain the risks, but essentially:
- Avoid whitelisting anything other than plain HTML elements
- Avoid whitelisting `script`, `style`, `iframe`, `object`, `embed`, `base` elements
- Avoid whitelisting anything other than plain HTML elements with simple values that you can match to a regexp
Example ¶
package main import ( "fmt" "regexp" "github.com/microcosm-cc/bluemonday" ) func main() { // Create a new policy p := bluemonday.NewPolicy() // Add elements to a policy without attributes p.AllowElements("b", "strong") // Add elements as a virtue of adding an attribute p.AllowAttrs("nowrap").OnElements("td", "th") // Attributes can either be added to all elements p.AllowAttrs("dir").Globally() //Or attributes can be added to specific elements p.AllowAttrs("value").OnElements("li") // It is ALWAYS recommended that an attribute be made to match a pattern // XSS in HTML attributes is a very easy attack vector // \p{L} matches unicode letters, \p{N} matches unicode numbers p.AllowAttrs("title").Matching(regexp.MustCompile(`[\p{L}\p{N}\s\-_',:\[\]!\./\\\(\)&]*`)).Globally() // You can stop at any time and call .Sanitize() // Assumes that string htmlIn was passed in from a HTTP POST and contains // untrusted user generated content htmlIn := `untrusted user generated content <body onload="alert('XSS')">` fmt.Println(p.Sanitize(htmlIn)) // And you can take any existing policy and extend it p = bluemonday.UGCPolicy() p.AllowElements("fieldset", "select", "option") // Links are complex beasts and one of the biggest attack vectors for // malicious content so we have included features specifically to help here. // This is not recommended: p = bluemonday.NewPolicy() p.AllowAttrs("href").Matching(regexp.MustCompile(`(?i)mailto|https?`)).OnElements("a") // The regexp is insufficient in this case to have prevented a malformed // value doing something unexpected. // This will ensure that URLs are not considered invalid by Go's net/url // package. p.RequireParseableURLs(true) // If you have enabled parseable URLs then the following option will allow // relative URLs. By default this is disabled and will prevent all local and // schema relative URLs (i.e. `href="//www.google.com"` is schema relative). p.AllowRelativeURLs(true) // If you have enabled parseable URLs then you can whitelist the schemas // that are permitted. Bear in mind that allowing relative URLs in the above // option allows for blank schemas. p.AllowURLSchemes("mailto", "http", "https") // Regardless of whether you have enabled parseable URLs, you can force all // URLs to have a rel="nofollow" attribute. This will be added if it does // not exist. // This applies to "a" "area" "link" elements that have a "href" attribute p.RequireNoFollowOnLinks(true) // We provide a convenience function that applies all of the above, but you // will still need to whitelist the linkable elements: p = bluemonday.NewPolicy() p.AllowStandardURLs() p.AllowAttrs("cite").OnElements("blockquote") p.AllowAttrs("href").OnElements("a", "area") p.AllowAttrs("src").OnElements("img") // Policy Building Helpers // If you've got this far and you're bored already, we also bundle some // other convenience functions p = bluemonday.NewPolicy() p.AllowStandardAttributes() p.AllowImages() p.AllowLists() p.AllowTables() }
Output:
Index ¶
- Variables
- func AlignContentHandler(value string) bool
- func AlignItemsHandler(value string) bool
- func AlignSelfHandler(value string) bool
- func AllHandler(value string) bool
- func AnimationDelayHandler(value string) bool
- func AnimationDirectionHandler(value string) bool
- func AnimationDurationHandler(value string) bool
- func AnimationFillModeHandler(value string) bool
- func AnimationHandler(value string) bool
- func AnimationIterationCountHandler(value string) bool
- func AnimationNameHandler(value string) bool
- func AnimationPlayStateHandler(value string) bool
- func BackfaceVisibilityHandler(value string) bool
- func BackgroundAttachmentHandler(value string) bool
- func BackgroundBlendModeHandler(value string) bool
- func BackgroundClipHandler(value string) bool
- func BackgroundHandler(value string) bool
- func BackgroundOriginHandler(value string) bool
- func BackgroundPositionHandler(value string) bool
- func BackgroundRepeatHandler(value string) bool
- func BackgroundSizeHandler(value string) bool
- func BaseHandler(value string) bool
- func BorderCollapseHandler(value string) bool
- func BorderHandler(value string) bool
- func BorderImageHandler(value string) bool
- func BorderImageOutsetHandler(value string) bool
- func BorderImageRepeatHandler(value string) bool
- func BorderImageSliceHandler(value string) bool
- func BorderImageWidthHandler(value string) bool
- func BorderRadiusHandler(value string) bool
- func BorderSideHandler(value string) bool
- func BorderSideRadiusHandler(value string) bool
- func BorderSideStyleHandler(value string) bool
- func BorderSideWidthHandler(value string) bool
- func BorderSpacingHandler(value string) bool
- func BorderStyleHandler(value string) bool
- func BorderWidthHandler(value string) bool
- func BoxDecorationBreakHandler(value string) bool
- func BoxShadowHandler(value string) bool
- func BoxSizingHandler(value string) bool
- func BreakBeforeAfterHandler(value string) bool
- func BreakInsideHandler(value string) bool
- func CaptionSideHandler(value string) bool
- func CaretColorHandler(value string) bool
- func ClearHandler(value string) bool
- func ClipHandler(value string) bool
- func ColorHandler(value string) bool
- func ColumnCountHandler(value string) bool
- func ColumnFillHandler(value string) bool
- func ColumnGapHandler(value string) bool
- func ColumnRuleHandler(value string) bool
- func ColumnRuleWidthHandler(value string) bool
- func ColumnSpanHandler(value string) bool
- func ColumnWidthHandler(value string) bool
- func ColumnsHandler(value string) bool
- func CursorHandler(value string) bool
- func DirectionHandler(value string) bool
- func DisplayHandler(value string) bool
- func EmptyCellsHandler(value string) bool
- func FilterHandler(value string) bool
- func FlexBasisHandler(value string) bool
- func FlexDirectionHandler(value string) bool
- func FlexFlowHandler(value string) bool
- func FlexGrowHandler(value string) bool
- func FlexHandler(value string) bool
- func FlexWrapHandler(value string) bool
- func FloatHandler(value string) bool
- func FontFamilyHandler(value string) bool
- func FontHandler(value string) bool
- func FontKerningHandler(value string) bool
- func FontLanguageOverrideHandler(value string) bool
- func FontSizeAdjustHandler(value string) bool
- func FontSizeHandler(value string) bool
- func FontStretchHandler(value string) bool
- func FontStyleHandler(value string) bool
- func FontSynthesisHandler(value string) bool
- func FontVariantCapsHandler(value string) bool
- func FontVariantHandler(value string) bool
- func FontVariantPositionHandler(value string) bool
- func FontWeightHandler(value string) bool
- func GridAreaHandler(value string) bool
- func GridAutoColumnsHandler(value string) bool
- func GridAutoFlowHandler(value string) bool
- func GridAxisStartEndHandler(value string) bool
- func GridColumnGapHandler(value string) bool
- func GridColumnHandler(value string) bool
- func GridGapHandler(value string) bool
- func GridHandler(value string) bool
- func GridRowHandler(value string) bool
- func GridTemplateAreasHandler(value string) bool
- func GridTemplateColumnsHandler(value string) bool
- func GridTemplateHandler(value string) bool
- func GridTemplateRowsHandler(value string) bool
- func HangingPunctuationHandler(value string) bool
- func HeightHandler(value string) bool
- func HyphensHandler(value string) bool
- func ImageHandler(value string) bool
- func ImageRenderingHandler(value string) bool
- func IsolationHandler(value string) bool
- func JustifyContentHandler(value string) bool
- func LengthHandler(value string) bool
- func LetterSpacingHandler(value string) bool
- func LineBreakHandler(value string) bool
- func LineHeightHandler(value string) bool
- func ListStyleHandler(value string) bool
- func ListStylePositionHandler(value string) bool
- func ListStyleTypeHandler(value string) bool
- func MarginHandler(value string) bool
- func MarginSideHandler(value string) bool
- func MaxHeightWidthHandler(value string) bool
- func MinHeightWidthHandler(value string) bool
- func MixBlendModeHandler(value string) bool
- func ObjectFitHandler(value string) bool
- func ObjectPositionHandler(value string) bool
- func OpacityHandler(value string) bool
- func OrderHandler(value string) bool
- func OrphansHandler(value string) bool
- func OutlineHandler(value string) bool
- func OutlineOffsetHandler(value string) bool
- func OutlineStyleHandler(value string) bool
- func OutlineWidthHandler(value string) bool
- func OverflowHandler(value string) bool
- func OverflowWrapHandler(value string) bool
- func OverflowXYHandler(value string) bool
- func PaddingHandler(value string) bool
- func PaddingSideHandler(value string) bool
- func PageBreakBeforeAfterHandler(value string) bool
- func PageBreakInsideHandler(value string) bool
- func PerspectiveHandler(value string) bool
- func PerspectiveOriginHandler(value string) bool
- func PointerEventsHandler(value string) bool
- func PositionHandler(value string) bool
- func QuotesHandler(value string) bool
- func ResizeHandler(value string) bool
- func ScrollBehaviorHandler(value string) bool
- func SideHandler(value string) bool
- func TabSizeHandler(value string) bool
- func TableLayoutHandler(value string) bool
- func TextAlignHandler(value string) bool
- func TextAlignLastHandler(value string) bool
- func TextCombineUprightHandler(value string) bool
- func TextDecorationHandler(value string) bool
- func TextDecorationLineHandler(value string) bool
- func TextDecorationStyleHandler(value string) bool
- func TextIndentHandler(value string) bool
- func TextJustifyHandler(value string) bool
- func TextOrientationHandler(value string) bool
- func TextOverflowHandler(value string) bool
- func TextShadowHandler(value string) bool
- func TextTransformHandler(value string) bool
- func TimingFunctionHandler(value string) bool
- func TransformHandler(value string) bool
- func TransformOriginHandler(value string) bool
- func TransformStyleHandler(value string) bool
- func TransitionDelayHandler(value string) bool
- func TransitionDurationHandler(value string) bool
- func TransitionHandler(value string) bool
- func TransitionPropertyHandler(value string) bool
- func UnicodeBidiHandler(value string) bool
- func UserSelectHandler(value string) bool
- func VerticalAlignHandler(value string) bool
- func VisiblityHandler(value string) bool
- func WhiteSpaceHandler(value string) bool
- func WidthHandler(value string) bool
- func WordBreakHandler(value string) bool
- func WordSpacingHandler(value string) bool
- func WordWrapHandler(value string) bool
- func WritingModeHandler(value string) bool
- func ZIndexHandler(value string) bool
- type Policy
- func (p *Policy) AddSpaceWhenStrippingTag(allow bool) *Policy
- func (p *Policy) AddTargetBlankToFullyQualifiedLinks(require bool) *Policy
- func (p *Policy) AllowAttrs(attrNames ...string) *attrPolicyBuilder
- func (p *Policy) AllowDataAttributes()
- func (p *Policy) AllowDataURIImages()
- func (p *Policy) AllowElements(names ...string) *Policy
- func (p *Policy) AllowElementsContent(names ...string) *Policy
- func (p *Policy) AllowElementsMatching(regex *regexp.Regexp) *Policy
- func (p *Policy) AllowImages()
- func (p *Policy) AllowLists()
- func (p *Policy) AllowNoAttrs() *attrPolicyBuilder
- func (p *Policy) AllowRelativeURLs(require bool) *Policy
- func (p *Policy) AllowStandardAttributes()
- func (p *Policy) AllowStandardURLs()
- func (p *Policy) AllowStyles(propertyNames ...string) *stylePolicyBuilder
- func (p *Policy) AllowStyling()
- func (p *Policy) AllowTables()
- func (p *Policy) AllowURLSchemeWithCustomPolicy(scheme string, urlPolicy func(url *url.URL) (allowUrl bool)) *Policy
- func (p *Policy) AllowURLSchemes(schemes ...string) *Policy
- func (p *Policy) RequireCrossOriginAnonymous(require bool) *Policy
- func (p *Policy) RequireNoFollowOnFullyQualifiedLinks(require bool) *Policy
- func (p *Policy) RequireNoFollowOnLinks(require bool) *Policy
- func (p *Policy) RequireNoReferrerOnFullyQualifiedLinks(require bool) *Policy
- func (p *Policy) RequireNoReferrerOnLinks(require bool) *Policy
- func (p *Policy) RequireParseableURLs(require bool) *Policy
- func (p *Policy) Sanitize(s string) string
- func (p *Policy) SanitizeBytes(b []byte) []byte
- func (p *Policy) SanitizeReader(r io.Reader) *bytes.Buffer
- func (p *Policy) SkipElementsContent(names ...string) *Policy
- type Query
Examples ¶
Constants ¶
This section is empty.
Variables ¶
var ( // CellAlign handles the `align` attribute // https://developer.mozilla.org/en-US/docs/Web/HTML/Element/td#attr-align CellAlign = regexp.MustCompile(`(?i)^(center|justify|left|right|char)$`) // CellVerticalAlign handles the `valign` attribute // https://developer.mozilla.org/en-US/docs/Web/HTML/Element/td#attr-valign CellVerticalAlign = regexp.MustCompile(`(?i)^(baseline|bottom|middle|top)$`) // Direction handles the `dir` attribute // https://developer.mozilla.org/en-US/docs/Web/HTML/Element/bdo#attr-dir Direction = regexp.MustCompile(`(?i)^(rtl|ltr)$`) // ImageAlign handles the `align` attribute on the `image` tag // http://www.w3.org/MarkUp/Test/Img/imgtest.html ImageAlign = regexp.MustCompile( `(?i)^(left|right|top|texttop|middle|absmiddle|baseline|bottom|absbottom)$`, ) // Integer describes whole positive integers (including 0) used in places // like td.colspan // https://developer.mozilla.org/en-US/docs/Web/HTML/Element/td#attr-colspan Integer = regexp.MustCompile(`^[0-9]+$`) // ISO8601 according to the W3 group is only a subset of the ISO8601 // standard: http://www.w3.org/TR/NOTE-datetime // // Used in places like time.datetime // https://developer.mozilla.org/en-US/docs/Web/HTML/Element/time#attr-datetime // // Matches patterns: // Year: // YYYY (eg 1997) // Year and month: // YYYY-MM (eg 1997-07) // Complete date: // YYYY-MM-DD (eg 1997-07-16) // Complete date plus hours and minutes: // YYYY-MM-DDThh:mmTZD (eg 1997-07-16T19:20+01:00) // Complete date plus hours, minutes and seconds: // YYYY-MM-DDThh:mm:ssTZD (eg 1997-07-16T19:20:30+01:00) // Complete date plus hours, minutes, seconds and a decimal fraction of a // second // YYYY-MM-DDThh:mm:ss.sTZD (eg 1997-07-16T19:20:30.45+01:00) ISO8601 = regexp.MustCompile( `^[0-9]{4}(-[0-9]{2}(-[0-9]{2}([ T][0-9]{2}(:[0-9]{2}){1,2}(.[0-9]{1,6})` + `?Z?([\+-][0-9]{2}:[0-9]{2})?)?)?)?$`, ) // ListType encapsulates the common value as well as the latest spec // values for lists // https://developer.mozilla.org/en-US/docs/Web/HTML/Element/ol#attr-type ListType = regexp.MustCompile(`(?i)^(circle|disc|square|a|A|i|I|1)$`) // SpaceSeparatedTokens is used in places like `a.rel` and the common attribute // `class` which both contain space delimited lists of data tokens // http://www.w3.org/TR/html-markup/datatypes.html#common.data.tokens-def // Regexp: \p{L} matches unicode letters, \p{N} matches unicode numbers SpaceSeparatedTokens = regexp.MustCompile(`^([\s\p{L}\p{N}_-]+)$`) // Number is a double value used on HTML5 meter and progress elements // http://www.whatwg.org/specs/web-apps/current-work/multipage/the-button-element.html#the-meter-element Number = regexp.MustCompile(`^[-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?$`) // NumberOrPercent is used predominantly as units of measurement in width // and height attributes // https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img#attr-height NumberOrPercent = regexp.MustCompile(`^[0-9]+[%]?$`) // Paragraph of text in an attribute such as *.'title', img.alt, etc // https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes#attr-title // Note that we are not allowing chars that could close tags like '>' Paragraph = regexp.MustCompile(`^[\p{L}\p{N}\s\-_',\[\]!\./\\\(\)]*$`) )
A selection of regular expressions that can be used as .Matching() rules on HTML attributes.
Functions ¶
func AlignContentHandler ¶ added in v1.0.3
func AlignItemsHandler ¶ added in v1.0.3
func AlignSelfHandler ¶ added in v1.0.3
func AllHandler ¶ added in v1.0.3
func AnimationDelayHandler ¶ added in v1.0.3
func AnimationDirectionHandler ¶ added in v1.0.3
func AnimationDurationHandler ¶ added in v1.0.3
func AnimationFillModeHandler ¶ added in v1.0.3
func AnimationHandler ¶ added in v1.0.3
func AnimationIterationCountHandler ¶ added in v1.0.3
func AnimationNameHandler ¶ added in v1.0.3
func AnimationPlayStateHandler ¶ added in v1.0.3
func BackfaceVisibilityHandler ¶ added in v1.0.3
func BackgroundAttachmentHandler ¶ added in v1.0.3
func BackgroundBlendModeHandler ¶ added in v1.0.3
func BackgroundClipHandler ¶ added in v1.0.3
func BackgroundHandler ¶ added in v1.0.3
func BackgroundOriginHandler ¶ added in v1.0.3
func BackgroundPositionHandler ¶ added in v1.0.3
func BackgroundRepeatHandler ¶ added in v1.0.3
func BackgroundSizeHandler ¶ added in v1.0.3
func BaseHandler ¶ added in v1.0.3
func BorderCollapseHandler ¶ added in v1.0.3
func BorderHandler ¶ added in v1.0.3
func BorderImageHandler ¶ added in v1.0.3
func BorderImageOutsetHandler ¶ added in v1.0.3
func BorderImageRepeatHandler ¶ added in v1.0.3
func BorderImageSliceHandler ¶ added in v1.0.3
func BorderImageWidthHandler ¶ added in v1.0.3
func BorderRadiusHandler ¶ added in v1.0.3
func BorderSideHandler ¶ added in v1.0.3
func BorderSideRadiusHandler ¶ added in v1.0.3
func BorderSideStyleHandler ¶ added in v1.0.3
func BorderSideWidthHandler ¶ added in v1.0.3
func BorderSpacingHandler ¶ added in v1.0.3
func BorderStyleHandler ¶ added in v1.0.3
func BorderWidthHandler ¶ added in v1.0.3
func BoxDecorationBreakHandler ¶ added in v1.0.3
func BoxShadowHandler ¶ added in v1.0.3
func BoxSizingHandler ¶ added in v1.0.3
func BreakBeforeAfterHandler ¶ added in v1.0.3
func BreakInsideHandler ¶ added in v1.0.3
func CaptionSideHandler ¶ added in v1.0.3
func CaretColorHandler ¶ added in v1.0.3
func ClearHandler ¶ added in v1.0.3
func ClipHandler ¶ added in v1.0.3
func ColorHandler ¶ added in v1.0.3
func ColumnCountHandler ¶ added in v1.0.3
func ColumnFillHandler ¶ added in v1.0.3
func ColumnGapHandler ¶ added in v1.0.3
func ColumnRuleHandler ¶ added in v1.0.3
func ColumnRuleWidthHandler ¶ added in v1.0.3
func ColumnSpanHandler ¶ added in v1.0.3
func ColumnWidthHandler ¶ added in v1.0.3
func ColumnsHandler ¶ added in v1.0.3
func CursorHandler ¶ added in v1.0.3
func DirectionHandler ¶ added in v1.0.3
func DisplayHandler ¶ added in v1.0.3
func EmptyCellsHandler ¶ added in v1.0.3
func FilterHandler ¶ added in v1.0.3
func FlexBasisHandler ¶ added in v1.0.3
func FlexDirectionHandler ¶ added in v1.0.3
func FlexFlowHandler ¶ added in v1.0.3
func FlexGrowHandler ¶ added in v1.0.3
func FlexHandler ¶ added in v1.0.3
func FlexWrapHandler ¶ added in v1.0.3
func FloatHandler ¶ added in v1.0.3
func FontFamilyHandler ¶ added in v1.0.3
func FontHandler ¶ added in v1.0.3
func FontKerningHandler ¶ added in v1.0.3
func FontLanguageOverrideHandler ¶ added in v1.0.3
func FontSizeAdjustHandler ¶ added in v1.0.3
func FontSizeHandler ¶ added in v1.0.3
func FontStretchHandler ¶ added in v1.0.3
func FontStyleHandler ¶ added in v1.0.3
func FontSynthesisHandler ¶ added in v1.0.3
func FontVariantCapsHandler ¶ added in v1.0.3
func FontVariantHandler ¶ added in v1.0.3
func FontVariantPositionHandler ¶ added in v1.0.3
func FontWeightHandler ¶ added in v1.0.3
func GridAreaHandler ¶ added in v1.0.3
func GridAutoColumnsHandler ¶ added in v1.0.3
func GridAutoFlowHandler ¶ added in v1.0.3
func GridAxisStartEndHandler ¶ added in v1.0.3
func GridColumnGapHandler ¶ added in v1.0.3
func GridColumnHandler ¶ added in v1.0.3
func GridGapHandler ¶ added in v1.0.3
func GridHandler ¶ added in v1.0.3
func GridRowHandler ¶ added in v1.0.3
func GridTemplateAreasHandler ¶ added in v1.0.3
func GridTemplateColumnsHandler ¶ added in v1.0.3
func GridTemplateHandler ¶ added in v1.0.3
func GridTemplateRowsHandler ¶ added in v1.0.3
func HangingPunctuationHandler ¶ added in v1.0.3
func HeightHandler ¶ added in v1.0.3
func HyphensHandler ¶ added in v1.0.3
func ImageHandler ¶ added in v1.0.3
func ImageRenderingHandler ¶ added in v1.0.3
func IsolationHandler ¶ added in v1.0.3
func JustifyContentHandler ¶ added in v1.0.3
func LengthHandler ¶ added in v1.0.3
func LetterSpacingHandler ¶ added in v1.0.3
func LineBreakHandler ¶ added in v1.0.3
func LineHeightHandler ¶ added in v1.0.3
func ListStyleHandler ¶ added in v1.0.3
func ListStylePositionHandler ¶ added in v1.0.3
func ListStyleTypeHandler ¶ added in v1.0.3
func MarginHandler ¶ added in v1.0.3
func MarginSideHandler ¶ added in v1.0.3
func MaxHeightWidthHandler ¶ added in v1.0.3
func MinHeightWidthHandler ¶ added in v1.0.3
func MixBlendModeHandler ¶ added in v1.0.3
func ObjectFitHandler ¶ added in v1.0.3
func ObjectPositionHandler ¶ added in v1.0.3
func OpacityHandler ¶ added in v1.0.3
func OrderHandler ¶ added in v1.0.3
func OrphansHandler ¶ added in v1.0.3
func OutlineHandler ¶ added in v1.0.3
func OutlineOffsetHandler ¶ added in v1.0.3
func OutlineStyleHandler ¶ added in v1.0.3
func OutlineWidthHandler ¶ added in v1.0.3
func OverflowHandler ¶ added in v1.0.3
func OverflowWrapHandler ¶ added in v1.0.3
func OverflowXYHandler ¶ added in v1.0.3
func PaddingHandler ¶ added in v1.0.3
func PaddingSideHandler ¶ added in v1.0.3
func PageBreakBeforeAfterHandler ¶ added in v1.0.3
func PageBreakInsideHandler ¶ added in v1.0.3
func PerspectiveHandler ¶ added in v1.0.3
func PerspectiveOriginHandler ¶ added in v1.0.3
func PointerEventsHandler ¶ added in v1.0.3
func PositionHandler ¶ added in v1.0.3
func QuotesHandler ¶ added in v1.0.3
func ResizeHandler ¶ added in v1.0.3
func ScrollBehaviorHandler ¶ added in v1.0.3
func SideHandler ¶ added in v1.0.3
func TabSizeHandler ¶ added in v1.0.3
func TableLayoutHandler ¶ added in v1.0.3
func TextAlignHandler ¶ added in v1.0.3
func TextAlignLastHandler ¶ added in v1.0.3
func TextCombineUprightHandler ¶ added in v1.0.3
func TextDecorationHandler ¶ added in v1.0.3
func TextDecorationLineHandler ¶ added in v1.0.3
func TextDecorationStyleHandler ¶ added in v1.0.3
func TextIndentHandler ¶ added in v1.0.3
func TextJustifyHandler ¶ added in v1.0.3
func TextOrientationHandler ¶ added in v1.0.3
func TextOverflowHandler ¶ added in v1.0.3
func TextShadowHandler ¶ added in v1.0.3
func TextTransformHandler ¶ added in v1.0.3
func TimingFunctionHandler ¶ added in v1.0.3
func TransformHandler ¶ added in v1.0.3
func TransformOriginHandler ¶ added in v1.0.3
func TransformStyleHandler ¶ added in v1.0.3
func TransitionDelayHandler ¶ added in v1.0.3
func TransitionDurationHandler ¶ added in v1.0.3
func TransitionHandler ¶ added in v1.0.3
func TransitionPropertyHandler ¶ added in v1.0.3
func UnicodeBidiHandler ¶ added in v1.0.3
func UserSelectHandler ¶ added in v1.0.3
func VerticalAlignHandler ¶ added in v1.0.3
func VisiblityHandler ¶ added in v1.0.3
func WhiteSpaceHandler ¶ added in v1.0.3
func WidthHandler ¶ added in v1.0.3
func WordBreakHandler ¶ added in v1.0.3
func WordSpacingHandler ¶ added in v1.0.3
func WordWrapHandler ¶ added in v1.0.3
func WritingModeHandler ¶ added in v1.0.3
func ZIndexHandler ¶ added in v1.0.3
Types ¶
type Policy ¶
type Policy struct {
// contains filtered or unexported fields
}
Policy encapsulates the whitelist of HTML elements and attributes that will be applied to the sanitised HTML.
You should use bluemonday.NewPolicy() to create a blank policy as the unexported fields contain maps that need to be initialized.
func NewPolicy ¶
func NewPolicy() *Policy
NewPolicy returns a blank policy with nothing whitelisted or permitted. This is the recommended way to start building a policy and you should now use AllowAttrs() and/or AllowElements() to construct the whitelist of HTML elements and attributes.
Example ¶
package main import ( "fmt" "github.com/microcosm-cc/bluemonday" ) func main() { // NewPolicy is a blank policy and we need to explicitly whitelist anything // that we wish to allow through p := bluemonday.NewPolicy() // We ensure any URLs are parseable and have rel="nofollow" where applicable p.AllowStandardURLs() // AllowStandardURLs already ensures that the href will be valid, and so we // can skip the .Matching() p.AllowAttrs("href").OnElements("a") // We allow paragraphs too p.AllowElements("p") html := p.Sanitize( `<p><a onblur="alert(secret)" href="http://www.google.com">Google</a></p>`, ) fmt.Println(html) }
Output: <p><a href="http://www.google.com" rel="nofollow">Google</a></p>
func StrictPolicy ¶
func StrictPolicy() *Policy
StrictPolicy returns an empty policy, which will effectively strip all HTML elements and their attributes from a document.
Example ¶
package main import ( "fmt" "github.com/microcosm-cc/bluemonday" ) func main() { // StrictPolicy is equivalent to NewPolicy and as nothing else is declared // we are stripping all elements (and their attributes) p := bluemonday.StrictPolicy() html := p.Sanitize( `Goodbye <a onblur="alert(secret)" href="http://en.wikipedia.org/wiki/Goodbye_Cruel_World_(Pink_Floyd_song)">Cruel</a> World`, ) fmt.Println(html) }
Output: Goodbye Cruel World
func StripTagsPolicy ¶
func StripTagsPolicy() *Policy
StripTagsPolicy is DEPRECATED. Use StrictPolicy instead.
func UGCPolicy ¶
func UGCPolicy() *Policy
UGCPolicy returns a policy aimed at user generated content that is a result of HTML WYSIWYG tools and Markdown conversions.
This is expected to be a fairly rich document where as much markup as possible should be retained. Markdown permits raw HTML so we are basically providing a policy to sanitise HTML5 documents safely but with the least intrusion on the formatting expectations of the user.
Example ¶
package main import ( "fmt" "github.com/microcosm-cc/bluemonday" ) func main() { // UGCPolicy is a convenience policy for user generated content. p := bluemonday.UGCPolicy() html := p.Sanitize( `<a onblur="alert(secret)" href="http://www.google.com">Google</a>`, ) fmt.Println(html) }
Output: <a href="http://www.google.com" rel="nofollow">Google</a>
func (*Policy) AddSpaceWhenStrippingTag ¶
AddSpaceWhenStrippingTag states whether to add a single space " " when removing tags that are not whitelisted by the policy.
This is useful if you expect to strip tags in dense markup and may lose the value of whitespace.
For example: "<p>Hello</p><p>World</p>"" would be sanitized to "HelloWorld" with the default value of false, but you may wish to sanitize this to " Hello World " by setting AddSpaceWhenStrippingTag to true as this would retain the intent of the text.
func (*Policy) AddTargetBlankToFullyQualifiedLinks ¶
AddTargetBlankToFullyQualifiedLinks will result in all a, area and link tags that point to a non-local destination (i.e. starts with a protocol and has a host) having a target="_blank" added to them if one does not already exist
Note: This requires p.RequireParseableURLs(true) and will enable it.
func (*Policy) AllowAttrs ¶
AllowAttrs takes a range of HTML attribute names and returns an attribute policy builder that allows you to specify the pattern and scope of the whitelisted attribute.
The attribute policy is only added to the core policy when either Globally() or OnElements(...) are called.
Example ¶
package main import ( "github.com/microcosm-cc/bluemonday" ) func main() { p := bluemonday.NewPolicy() // Allow the 'title' attribute on every HTML element that has been // whitelisted p.AllowAttrs("title").Matching(bluemonday.Paragraph).Globally() // Allow the 'abbr' attribute on only the 'td' and 'th' elements. p.AllowAttrs("abbr").Matching(bluemonday.Paragraph).OnElements("td", "th") // Allow the 'colspan' and 'rowspan' attributes, matching a positive integer // pattern, on only the 'td' and 'th' elements. p.AllowAttrs("colspan", "rowspan").Matching( bluemonday.Integer, ).OnElements("td", "th") }
Output:
func (*Policy) AllowDataAttributes ¶
func (p *Policy) AllowDataAttributes()
AllowDataAttributes whitelists all data attributes. We can't specify the name of each attribute exactly as they are customized.
NOTE: These values are not sanitized and applications that evaluate or process them without checking and verification of the input may be at risk if this option is enabled. This is a 'caveat emptor' option and the person enabling this option needs to fully understand the potential impact with regards to whatever application will be consuming the sanitized HTML afterwards, i.e. if you know you put a link in a data attribute and use that to automatically load some new window then you're giving the author of a HTML fragment the means to open a malicious destination automatically. Use with care!
func (*Policy) AllowDataURIImages ¶
func (p *Policy) AllowDataURIImages()
AllowDataURIImages permits the use of inline images defined in RFC2397 http://tools.ietf.org/html/rfc2397 http://en.wikipedia.org/wiki/Data_URI_scheme
Images must have a mimetype matching:
image/gif image/jpeg image/png image/webp
NOTE: There is a potential security risk to allowing data URIs and you should only permit them on content you already trust. http://palizine.plynt.com/issues/2010Oct/bypass-xss-filters/ https://capec.mitre.org/data/definitions/244.html
func (*Policy) AllowElements ¶
AllowElements will append HTML elements to the whitelist without applying an attribute policy to those elements (the elements are permitted sans-attributes)
Example ¶
package main import ( "github.com/microcosm-cc/bluemonday" ) func main() { p := bluemonday.NewPolicy() // Allow styling elements without attributes p.AllowElements("br", "div", "hr", "p", "span") }
Output:
func (*Policy) AllowElementsContent ¶
AllowElementsContent marks the HTML elements whose content should be retained after removing the tag.
func (*Policy) AllowElementsMatching ¶ added in v1.0.3
func (*Policy) AllowImages ¶
func (p *Policy) AllowImages()
AllowImages enables the img element and some popular attributes. It will also ensure that URL values are parseable. This helper does not enable data URI images, for that you should also use the AllowDataURIImages() helper.
func (*Policy) AllowLists ¶
func (p *Policy) AllowLists()
AllowLists will enabled ordered and unordered lists, as well as definition lists
func (*Policy) AllowNoAttrs ¶
func (p *Policy) AllowNoAttrs() *attrPolicyBuilder
AllowNoAttrs says that attributes on element are optional.
The attribute policy is only added to the core policy when OnElements(...) are called.
func (*Policy) AllowRelativeURLs ¶
AllowRelativeURLs enables RequireParseableURLs and then permits URLs that are parseable, have no schema information and url.IsAbs() returns false This permits local URLs
func (*Policy) AllowStandardAttributes ¶
func (p *Policy) AllowStandardAttributes()
AllowStandardAttributes will enable "id", "title" and the language specific attributes "dir" and "lang" on all elements that are whitelisted
func (*Policy) AllowStandardURLs ¶
func (p *Policy) AllowStandardURLs()
AllowStandardURLs is a convenience function that will enable rel="nofollow" on "a", "area" and "link" (if you have allowed those elements) and will ensure that the URL values are parseable and either relative or belong to the "mailto", "http", or "https" schemes
func (*Policy) AllowStyles ¶ added in v1.0.3
AllowStyles takes a range of CSS property names and returns a style policy builder that allows you to specify the pattern and scope of the whitelisted property.
The style policy is only added to the core policy when either Globally() or OnElements(...) are called.
Example ¶
package main import ( "fmt" "regexp" "github.com/microcosm-cc/bluemonday" ) func main() { p := bluemonday.NewPolicy() // Allow only 'span' and 'p' elements p.AllowElements("span", "p", "strong") // Only allow 'style' attributes on 'span' and 'p' elements p.AllowAttrs("style").OnElements("span", "p") // Allow the 'text-decoration' property to be set to 'underline', 'line-through' or 'none' // on 'span' elements only p.AllowStyles("text-decoration").MatchingEnum("underline", "line-through", "none").OnElements("span") // Allow the 'color' property with valid RGB(A) hex values only // on every HTML element that has been whitelisted p.AllowStyles("color").Matching(regexp.MustCompile("(?i)^#([0-9a-f]{3,4}|[0-9a-f]{6}|[0-9a-f]{8})$")).Globally() // Default handler p.AllowStyles("background-origin").Globally() // The span has an invalid 'color' which will be stripped along with other disallowed properties html := p.Sanitize( `<p style="color:#f00;"> <span style="text-decoration: underline; background-image: url(javascript:alert('XSS')); color: #f00ba; background-origin: invalidValue"> Red underlined <strong style="text-decoration:none;">text</strong> </span> </p>`, ) fmt.Println(html) }
Output: <p style="color: #f00"> <span style="text-decoration: underline"> Red underlined <strong>text</strong> </span> </p>
func (*Policy) AllowStyling ¶
func (p *Policy) AllowStyling()
AllowStyling presently enables the class attribute globally.
Note: When bluemonday ships a CSS parser and we can safely sanitise that, this will also allow sanitized styling of elements via the style attribute.
func (*Policy) AllowTables ¶
func (p *Policy) AllowTables()
AllowTables will enable a rich set of elements and attributes to describe HTML tables
func (*Policy) AllowURLSchemeWithCustomPolicy ¶
func (p *Policy) AllowURLSchemeWithCustomPolicy( scheme string, urlPolicy func(url *url.URL) (allowUrl bool), ) *Policy
AllowURLSchemeWithCustomPolicy will append URL schemes with a custom URL policy to the whitelist. Only the URLs with matching schema and urlPolicy(url) returning true will be allowed.
func (*Policy) AllowURLSchemes ¶
AllowURLSchemes will append URL schemes to the whitelist Example: p.AllowURLSchemes("mailto", "http", "https")
func (*Policy) RequireCrossOriginAnonymous ¶ added in v1.0.6
RequireCrossOriginAnonymous will result in all audio, img, link, script, and video tags having a crossorigin="anonymous" added to them if one does not already exist
func (*Policy) RequireNoFollowOnFullyQualifiedLinks ¶
RequireNoFollowOnFullyQualifiedLinks will result in all a, area, and link tags that point to a non-local destination (i.e. starts with a protocol and has a host) having a rel="nofollow" added to them if one does not already exist
Note: This requires p.RequireParseableURLs(true) and will enable it.
func (*Policy) RequireNoFollowOnLinks ¶
RequireNoFollowOnLinks will result in all a, area, link tags having a rel="nofollow"added to them if one does not already exist
Note: This requires p.RequireParseableURLs(true) and will enable it.
func (*Policy) RequireNoReferrerOnFullyQualifiedLinks ¶ added in v1.0.3
RequireNoReferrerOnFullyQualifiedLinks will result in all a, area, and link tags that point to a non-local destination (i.e. starts with a protocol and has a host) having a rel="noreferrer" added to them if one does not already exist
Note: This requires p.RequireParseableURLs(true) and will enable it.
func (*Policy) RequireNoReferrerOnLinks ¶ added in v1.0.3
RequireNoReferrerOnLinks will result in all a, area, and link tags having a rel="noreferrrer" added to them if one does not already exist
Note: This requires p.RequireParseableURLs(true) and will enable it.
func (*Policy) RequireParseableURLs ¶
RequireParseableURLs will result in all URLs requiring that they be parseable by "net/url" url.Parse() This applies to: - a.href - area.href - blockquote.cite - img.src - link.href - script.src
func (*Policy) Sanitize ¶
Sanitize takes a string that contains a HTML fragment or document and applies the given policy whitelist.
It returns a HTML string that has been sanitized by the policy or an empty string if an error has occurred (most likely as a consequence of extremely malformed input)
Example ¶
package main import ( "fmt" "github.com/microcosm-cc/bluemonday" ) func main() { // UGCPolicy is a convenience policy for user generated content. p := bluemonday.UGCPolicy() // string in, string out html := p.Sanitize(`<a onblur="alert(secret)" href="http://www.google.com">Google</a>`) fmt.Println(html) }
Output: <a href="http://www.google.com" rel="nofollow">Google</a>
func (*Policy) SanitizeBytes ¶
SanitizeBytes takes a []byte that contains a HTML fragment or document and applies the given policy whitelist.
It returns a []byte containing the HTML that has been sanitized by the policy or an empty []byte if an error has occurred (most likely as a consequence of extremely malformed input)
Example ¶
package main import ( "fmt" "github.com/microcosm-cc/bluemonday" ) func main() { // UGCPolicy is a convenience policy for user generated content. p := bluemonday.UGCPolicy() // []byte in, []byte out b := []byte(`<a onblur="alert(secret)" href="http://www.google.com">Google</a>`) b = p.SanitizeBytes(b) fmt.Println(string(b)) }
Output: <a href="http://www.google.com" rel="nofollow">Google</a>
func (*Policy) SanitizeReader ¶
SanitizeReader takes an io.Reader that contains a HTML fragment or document and applies the given policy whitelist.
It returns a bytes.Buffer containing the HTML that has been sanitized by the policy. Errors during sanitization will merely return an empty result.
Example ¶
package main import ( "fmt" "strings" "github.com/microcosm-cc/bluemonday" ) func main() { // UGCPolicy is a convenience policy for user generated content. p := bluemonday.UGCPolicy() // io.Reader in, bytes.Buffer out r := strings.NewReader(`<a onblur="alert(secret)" href="http://www.google.com">Google</a>`) buf := p.SanitizeReader(r) fmt.Println(buf.String()) }
Output: <a href="http://www.google.com" rel="nofollow">Google</a>
func (*Policy) SkipElementsContent ¶
SkipElementsContent adds the HTML elements whose tags is needed to be removed with its content.
Source Files ¶
Directories ¶
Path | Synopsis |
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cmd
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sanitise_html_email
Package main demonstrates a HTML email cleaner.
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Package main demonstrates a HTML email cleaner. |
sanitise_ugc
Package main demonstrates a simple user generated content sanitizer.
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Package main demonstrates a simple user generated content sanitizer. |