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First commit
This commit is contained in:
Frédéric Guillot
commit
8ffb773f43
2121 changed files with 1118910 additions and 0 deletions
360
reader/sanitizer/sanitizer.go
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360
reader/sanitizer/sanitizer.go
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// Copyright 2017 Frédéric Guillot. All rights reserved.
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// Use of this source code is governed by the Apache 2.0
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// license that can be found in the LICENSE file.
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package sanitizer
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import (
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"bytes"
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"fmt"
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"github.com/miniflux/miniflux2/reader/url"
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"io"
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"strings"
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"golang.org/x/net/html"
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)
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// Sanitize returns safe HTML.
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func Sanitize(baseURL, input string) string {
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tokenizer := html.NewTokenizer(bytes.NewBufferString(input))
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var buffer bytes.Buffer
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var tagStack []string
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for {
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if tokenizer.Next() == html.ErrorToken {
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err := tokenizer.Err()
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if err == io.EOF {
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return buffer.String()
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}
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return ""
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}
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token := tokenizer.Token()
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switch token.Type {
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case html.TextToken:
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buffer.WriteString(token.Data)
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case html.StartTagToken:
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tagName := token.DataAtom.String()
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if !isPixelTracker(tagName, token.Attr) && isValidTag(tagName) {
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attrNames, htmlAttributes := sanitizeAttributes(baseURL, tagName, token.Attr)
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if hasRequiredAttributes(tagName, attrNames) {
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if len(attrNames) > 0 {
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buffer.WriteString("<" + tagName + " " + htmlAttributes + ">")
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} else {
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buffer.WriteString("<" + tagName + ">")
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}
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tagStack = append(tagStack, tagName)
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}
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}
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case html.EndTagToken:
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tagName := token.DataAtom.String()
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if isValidTag(tagName) && inList(tagName, tagStack) {
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buffer.WriteString(fmt.Sprintf("</%s>", tagName))
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}
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case html.SelfClosingTagToken:
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tagName := token.DataAtom.String()
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if !isPixelTracker(tagName, token.Attr) && isValidTag(tagName) {
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attrNames, htmlAttributes := sanitizeAttributes(baseURL, tagName, token.Attr)
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if hasRequiredAttributes(tagName, attrNames) {
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if len(attrNames) > 0 {
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buffer.WriteString("<" + tagName + " " + htmlAttributes + "/>")
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} else {
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buffer.WriteString("<" + tagName + "/>")
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}
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}
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}
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}
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}
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}
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func sanitizeAttributes(baseURL, tagName string, attributes []html.Attribute) (attrNames []string, html string) {
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var htmlAttrs []string
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var err error
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for _, attribute := range attributes {
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value := attribute.Val
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if !isValidAttribute(tagName, attribute.Key) {
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continue
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}
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if isExternalResourceAttribute(attribute.Key) {
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if tagName == "iframe" && !isValidIframeSource(attribute.Val) {
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continue
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} else {
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value, err = url.GetAbsoluteURL(baseURL, value)
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if err != nil {
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continue
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}
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if !hasValidScheme(value) || isBlacklistedResource(value) {
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continue
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}
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}
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}
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attrNames = append(attrNames, attribute.Key)
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htmlAttrs = append(htmlAttrs, fmt.Sprintf(`%s="%s"`, attribute.Key, value))
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}
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extraAttrNames, extraHTMLAttributes := getExtraAttributes(tagName)
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if len(extraAttrNames) > 0 {
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attrNames = append(attrNames, extraAttrNames...)
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htmlAttrs = append(htmlAttrs, extraHTMLAttributes...)
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}
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return attrNames, strings.Join(htmlAttrs, " ")
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}
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func getExtraAttributes(tagName string) ([]string, []string) {
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if tagName == "a" {
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return []string{"rel", "target", "referrerpolicy"}, []string{`rel="noopener noreferrer"`, `target="_blank"`, `referrerpolicy="no-referrer"`}
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}
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if tagName == "video" || tagName == "audio" {
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return []string{"controls"}, []string{"controls"}
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}
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return nil, nil
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}
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func isValidTag(tagName string) bool {
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for element := range getTagWhitelist() {
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if tagName == element {
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return true
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}
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}
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return false
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}
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func isValidAttribute(tagName, attributeName string) bool {
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for element, attributes := range getTagWhitelist() {
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if tagName == element {
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if inList(attributeName, attributes) {
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return true
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}
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}
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}
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return false
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}
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func isExternalResourceAttribute(attribute string) bool {
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switch attribute {
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case "src", "href", "poster", "cite":
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return true
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default:
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return false
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}
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}
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func isPixelTracker(tagName string, attributes []html.Attribute) bool {
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if tagName == "img" {
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hasHeight := false
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hasWidth := false
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for _, attribute := range attributes {
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if attribute.Key == "height" && attribute.Val == "1" {
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hasHeight = true
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}
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if attribute.Key == "width" && attribute.Val == "1" {
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hasWidth = true
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}
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}
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return hasHeight && hasWidth
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}
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return false
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}
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func hasRequiredAttributes(tagName string, attributes []string) bool {
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elements := make(map[string][]string)
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elements["a"] = []string{"href"}
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elements["iframe"] = []string{"src"}
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elements["img"] = []string{"src"}
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elements["source"] = []string{"src"}
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for element, attrs := range elements {
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if tagName == element {
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for _, attribute := range attributes {
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for _, attr := range attrs {
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if attr == attribute {
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return true
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}
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}
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}
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return false
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}
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}
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return true
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}
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func hasValidScheme(src string) bool {
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// See https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml
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whitelist := []string{
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"apt://",
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"bitcoin://",
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"callto://",
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"ed2k://",
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"facetime://",
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"feed://",
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"ftp://",
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"geo://",
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"gopher://",
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"git://",
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"http://",
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"https://",
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"irc://",
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"irc6://",
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"ircs://",
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"itms://",
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"jabber://",
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"magnet://",
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"mailto://",
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"maps://",
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"news://",
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"nfs://",
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"nntp://",
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"rtmp://",
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"sip://",
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"sips://",
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"skype://",
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"smb://",
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"sms://",
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"spotify://",
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"ssh://",
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"sftp://",
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"steam://",
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"svn://",
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"tel://",
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"webcal://",
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"xmpp://",
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}
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for _, prefix := range whitelist {
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if strings.HasPrefix(src, prefix) {
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return true
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}
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}
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return false
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}
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func isBlacklistedResource(src string) bool {
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blacklist := []string{
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"feedsportal.com",
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"api.flattr.com",
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"stats.wordpress.com",
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"plus.google.com/share",
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"twitter.com/share",
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"feeds.feedburner.com",
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}
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for _, element := range blacklist {
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if strings.Contains(src, element) {
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return true
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}
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}
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return false
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}
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func isValidIframeSource(src string) bool {
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whitelist := []string{
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"http://www.youtube.com",
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"https://www.youtube.com",
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"http://player.vimeo.com",
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"https://player.vimeo.com",
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"http://www.dailymotion.com",
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"https://www.dailymotion.com",
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"http://vk.com",
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"https://vk.com",
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}
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for _, prefix := range whitelist {
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if strings.HasPrefix(src, prefix) {
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return true
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}
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}
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return false
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}
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func getTagWhitelist() map[string][]string {
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whitelist := make(map[string][]string)
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whitelist["img"] = []string{"alt", "title", "src"}
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whitelist["audio"] = []string{"src"}
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whitelist["video"] = []string{"poster", "height", "width", "src"}
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whitelist["source"] = []string{"src", "type"}
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whitelist["dt"] = []string{}
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whitelist["dd"] = []string{}
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whitelist["dl"] = []string{}
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whitelist["table"] = []string{}
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whitelist["caption"] = []string{}
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whitelist["thead"] = []string{}
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whitelist["tfooter"] = []string{}
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whitelist["tr"] = []string{}
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whitelist["td"] = []string{"rowspan", "colspan"}
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whitelist["th"] = []string{"rowspan", "colspan"}
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whitelist["h1"] = []string{}
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whitelist["h2"] = []string{}
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whitelist["h3"] = []string{}
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whitelist["h4"] = []string{}
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whitelist["h5"] = []string{}
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whitelist["h6"] = []string{}
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whitelist["strong"] = []string{}
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whitelist["em"] = []string{}
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whitelist["code"] = []string{}
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whitelist["pre"] = []string{}
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whitelist["blockquote"] = []string{}
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whitelist["q"] = []string{"cite"}
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whitelist["p"] = []string{}
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whitelist["ul"] = []string{}
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whitelist["li"] = []string{}
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whitelist["ol"] = []string{}
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whitelist["br"] = []string{}
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whitelist["del"] = []string{}
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whitelist["a"] = []string{"href", "title"}
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whitelist["figure"] = []string{}
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whitelist["figcaption"] = []string{}
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whitelist["cite"] = []string{}
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whitelist["time"] = []string{"datetime"}
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whitelist["abbr"] = []string{"title"}
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whitelist["acronym"] = []string{"title"}
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whitelist["wbr"] = []string{}
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whitelist["dfn"] = []string{}
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whitelist["sub"] = []string{}
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whitelist["sup"] = []string{}
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whitelist["var"] = []string{}
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whitelist["samp"] = []string{}
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whitelist["s"] = []string{}
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whitelist["del"] = []string{}
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whitelist["ins"] = []string{}
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whitelist["kbd"] = []string{}
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whitelist["rp"] = []string{}
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whitelist["rt"] = []string{}
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whitelist["rtc"] = []string{}
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whitelist["ruby"] = []string{}
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whitelist["iframe"] = []string{"width", "height", "frameborder", "src", "allowfullscreen"}
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return whitelist
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}
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func inList(needle string, haystack []string) bool {
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for _, element := range haystack {
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if element == needle {
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return true
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}
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}
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return false
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}
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