Update to bluemonday-1.0.6 (#15294)

Signed-off-by: Andrew Thornton <art27@cantab.net>

vendor/github.com/microcosm-cc/bluemonday/sanitize.go

@@ -39,7 +39,7 @@ import (
 
 	"golang.org/x/net/html"
 
-	cssparser "github.com/chris-ramon/douceur/parser"
+	"github.com/aymerick/douceur/parser"
 )
 
 var (
@@ -286,7 +286,7 @@ func (p *Policy) sanitize(r io.Reader) *bytes.Buffer {
 
 		case html.StartTagToken:
 
-			mostRecentlyStartedToken = strings.ToLower(token.Data)
+			mostRecentlyStartedToken = normaliseElementName(token.Data)
 
 			aps, ok := p.elsAndAttrs[token.Data]
 			if !ok {
@@ -329,7 +329,7 @@ func (p *Policy) sanitize(r io.Reader) *bytes.Buffer {
 
 		case html.EndTagToken:
 
-			if mostRecentlyStartedToken == strings.ToLower(token.Data) {
+			if mostRecentlyStartedToken == normaliseElementName(token.Data) {
 				mostRecentlyStartedToken = ""
 			}
 
@@ -407,11 +407,11 @@ func (p *Policy) sanitize(r io.Reader) *bytes.Buffer {
 
 			if !skipElementContent {
 				switch mostRecentlyStartedToken {
-				case "script":
+				case `script`:
 					// not encouraged, but if a policy allows JavaScript we
 					// should not HTML escape it as that would break the output
 					buff.WriteString(token.Data)
-				case "style":
+				case `style`:
 					// not encouraged, but if a policy allows CSS styles we
 					// should not HTML escape it as that would break the output
 					buff.WriteString(token.Data)
@@ -721,6 +721,26 @@ func (p *Policy) sanitizeAttrs(
 		}
 	}
 
+	if p.requireCrossOriginAnonymous && len(cleanAttrs) > 0 {
+		switch elementName {
+		case "audio", "img", "link", "script", "video":
+			var crossOriginFound bool
+			for _, htmlAttr := range cleanAttrs {
+				if htmlAttr.Key == "crossorigin" {
+					crossOriginFound = true
+					htmlAttr.Val = "anonymous"
+				}
+			}
+
+			if !crossOriginFound {
+				crossOrigin := html.Attribute{}
+				crossOrigin.Key = "crossorigin"
+				crossOrigin.Val = "anonymous"
+				cleanAttrs = append(cleanAttrs, crossOrigin)
+			}
+		}
+	}
+
 	return cleanAttrs
 }
 
@@ -744,7 +764,7 @@ func (p *Policy) sanitizeStyles(attr html.Attribute, elementName string) html.At
 	if len(attr.Val) > 0 && attr.Val[len(attr.Val)-1] != ';' {
 		attr.Val = attr.Val + ";"
 	}
-	decs, err := cssparser.ParseDeclarations(attr.Val)
+	decs, err := parser.ParseDeclarations(attr.Val)
 	if err != nil {
 		attr.Val = ""
 		return attr
@@ -944,3 +964,23 @@ func (p *Policy) matchRegex(elementName string) (map[string]attrPolicy, bool) {
 	}
 	return aps, matched
 }
+
+
+// normaliseElementName takes a HTML element like <script> which is user input
+// and returns a lower case version of it that is immune to UTF-8 to ASCII
+// conversion tricks (like the use of upper case cyrillic i scrİpt which a
+// strings.ToLower would convert to script). Instead this func will preserve
+// all non-ASCII as their escaped equivalent, i.e. \u0130 which reveals the
+// characters when lower cased
+func normaliseElementName(str string) string {
+	// that useful QuoteToASCII put quote marks at the start and end
+	// so those are trimmed off
+	return strings.TrimSuffix(
+		strings.TrimPrefix(
+			strings.ToLower(
+				strconv.QuoteToASCII(str),
+			),
+			`"`),
+		`"`,
+	)
+}