GoToSocial/vendor/github.com/yuin/goldmark/renderer/html/html.go

1027 lines
27 KiB
Go

// Package html implements renderer that outputs HTMLs.
package html
import (
"bytes"
"fmt"
"strconv"
"unicode"
"unicode/utf8"
"github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/renderer"
"github.com/yuin/goldmark/util"
)
// A Config struct has configurations for the HTML based renderers.
type Config struct {
Writer Writer
HardWraps bool
EastAsianLineBreaks EastAsianLineBreaks
XHTML bool
Unsafe bool
}
// NewConfig returns a new Config with defaults.
func NewConfig() Config {
return Config{
Writer: DefaultWriter,
HardWraps: false,
EastAsianLineBreaks: EastAsianLineBreaksNone,
XHTML: false,
Unsafe: false,
}
}
// SetOption implements renderer.NodeRenderer.SetOption.
func (c *Config) SetOption(name renderer.OptionName, value interface{}) {
switch name {
case optHardWraps:
c.HardWraps = value.(bool)
case optEastAsianLineBreaks:
c.EastAsianLineBreaks = value.(EastAsianLineBreaks)
case optXHTML:
c.XHTML = value.(bool)
case optUnsafe:
c.Unsafe = value.(bool)
case optTextWriter:
c.Writer = value.(Writer)
}
}
// An Option interface sets options for HTML based renderers.
type Option interface {
SetHTMLOption(*Config)
}
// TextWriter is an option name used in WithWriter.
const optTextWriter renderer.OptionName = "Writer"
type withWriter struct {
value Writer
}
func (o *withWriter) SetConfig(c *renderer.Config) {
c.Options[optTextWriter] = o.value
}
func (o *withWriter) SetHTMLOption(c *Config) {
c.Writer = o.value
}
// WithWriter is a functional option that allow you to set the given writer to
// the renderer.
func WithWriter(writer Writer) interface {
renderer.Option
Option
} {
return &withWriter{writer}
}
// HardWraps is an option name used in WithHardWraps.
const optHardWraps renderer.OptionName = "HardWraps"
type withHardWraps struct {
}
func (o *withHardWraps) SetConfig(c *renderer.Config) {
c.Options[optHardWraps] = true
}
func (o *withHardWraps) SetHTMLOption(c *Config) {
c.HardWraps = true
}
// WithHardWraps is a functional option that indicates whether softline breaks
// should be rendered as '<br>'.
func WithHardWraps() interface {
renderer.Option
Option
} {
return &withHardWraps{}
}
// EastAsianLineBreaks is an option name used in WithEastAsianLineBreaks.
const optEastAsianLineBreaks renderer.OptionName = "EastAsianLineBreaks"
// A EastAsianLineBreaks is a style of east asian line breaks.
type EastAsianLineBreaks int
const (
//EastAsianLineBreaksNone renders line breaks as it is.
EastAsianLineBreaksNone EastAsianLineBreaks = iota
// EastAsianLineBreaksSimple follows east_asian_line_breaks in Pandoc.
EastAsianLineBreaksSimple
// EastAsianLineBreaksCSS3Draft follows CSS text level3 "Segment Break Transformation Rules" with some enhancements.
EastAsianLineBreaksCSS3Draft
)
func (b EastAsianLineBreaks) softLineBreak(thisLastRune rune, siblingFirstRune rune) bool {
switch b {
case EastAsianLineBreaksNone:
return false
case EastAsianLineBreaksSimple:
return !(util.IsEastAsianWideRune(thisLastRune) && util.IsEastAsianWideRune(siblingFirstRune))
case EastAsianLineBreaksCSS3Draft:
return eastAsianLineBreaksCSS3DraftSoftLineBreak(thisLastRune, siblingFirstRune)
}
return false
}
func eastAsianLineBreaksCSS3DraftSoftLineBreak(thisLastRune rune, siblingFirstRune rune) bool {
// Implements CSS text level3 Segment Break Transformation Rules with some enhancements.
// References:
// - https://www.w3.org/TR/2020/WD-css-text-3-20200429/#line-break-transform
// - https://github.com/w3c/csswg-drafts/issues/5086
// Rule1:
// If the character immediately before or immediately after the segment break is
// the zero-width space character (U+200B), then the break is removed, leaving behind the zero-width space.
if thisLastRune == '\u200B' || siblingFirstRune == '\u200B' {
return false
}
// Rule2:
// Otherwise, if the East Asian Width property of both the character before and after the segment break is
// F, W, or H (not A), and neither side is Hangul, then the segment break is removed.
thisLastRuneEastAsianWidth := util.EastAsianWidth(thisLastRune)
siblingFirstRuneEastAsianWidth := util.EastAsianWidth(siblingFirstRune)
if (thisLastRuneEastAsianWidth == "F" ||
thisLastRuneEastAsianWidth == "W" ||
thisLastRuneEastAsianWidth == "H") &&
(siblingFirstRuneEastAsianWidth == "F" ||
siblingFirstRuneEastAsianWidth == "W" ||
siblingFirstRuneEastAsianWidth == "H") {
return unicode.Is(unicode.Hangul, thisLastRune) || unicode.Is(unicode.Hangul, siblingFirstRune)
}
// Rule3:
// Otherwise, if either the character before or after the segment break belongs to
// the space-discarding character set and it is a Unicode Punctuation (P*) or U+3000,
// then the segment break is removed.
if util.IsSpaceDiscardingUnicodeRune(thisLastRune) ||
unicode.IsPunct(thisLastRune) ||
thisLastRune == '\u3000' ||
util.IsSpaceDiscardingUnicodeRune(siblingFirstRune) ||
unicode.IsPunct(siblingFirstRune) ||
siblingFirstRune == '\u3000' {
return false
}
// Rule4:
// Otherwise, the segment break is converted to a space (U+0020).
return true
}
type withEastAsianLineBreaks struct {
eastAsianLineBreaksStyle EastAsianLineBreaks
}
func (o *withEastAsianLineBreaks) SetConfig(c *renderer.Config) {
c.Options[optEastAsianLineBreaks] = o.eastAsianLineBreaksStyle
}
func (o *withEastAsianLineBreaks) SetHTMLOption(c *Config) {
c.EastAsianLineBreaks = o.eastAsianLineBreaksStyle
}
// WithEastAsianLineBreaks is a functional option that indicates whether softline breaks
// between east asian wide characters should be ignored.
func WithEastAsianLineBreaks(e EastAsianLineBreaks) interface {
renderer.Option
Option
} {
return &withEastAsianLineBreaks{e}
}
// XHTML is an option name used in WithXHTML.
const optXHTML renderer.OptionName = "XHTML"
type withXHTML struct {
}
func (o *withXHTML) SetConfig(c *renderer.Config) {
c.Options[optXHTML] = true
}
func (o *withXHTML) SetHTMLOption(c *Config) {
c.XHTML = true
}
// WithXHTML is a functional option indicates that nodes should be rendered in
// xhtml instead of HTML5.
func WithXHTML() interface {
Option
renderer.Option
} {
return &withXHTML{}
}
// Unsafe is an option name used in WithUnsafe.
const optUnsafe renderer.OptionName = "Unsafe"
type withUnsafe struct {
}
func (o *withUnsafe) SetConfig(c *renderer.Config) {
c.Options[optUnsafe] = true
}
func (o *withUnsafe) SetHTMLOption(c *Config) {
c.Unsafe = true
}
// WithUnsafe is a functional option that renders dangerous contents
// (raw htmls and potentially dangerous links) as it is.
func WithUnsafe() interface {
renderer.Option
Option
} {
return &withUnsafe{}
}
// A Renderer struct is an implementation of renderer.NodeRenderer that renders
// nodes as (X)HTML.
type Renderer struct {
Config
}
// NewRenderer returns a new Renderer with given options.
func NewRenderer(opts ...Option) renderer.NodeRenderer {
r := &Renderer{
Config: NewConfig(),
}
for _, opt := range opts {
opt.SetHTMLOption(&r.Config)
}
return r
}
// RegisterFuncs implements NodeRenderer.RegisterFuncs .
func (r *Renderer) RegisterFuncs(reg renderer.NodeRendererFuncRegisterer) {
// blocks
reg.Register(ast.KindDocument, r.renderDocument)
reg.Register(ast.KindHeading, r.renderHeading)
reg.Register(ast.KindBlockquote, r.renderBlockquote)
reg.Register(ast.KindCodeBlock, r.renderCodeBlock)
reg.Register(ast.KindFencedCodeBlock, r.renderFencedCodeBlock)
reg.Register(ast.KindHTMLBlock, r.renderHTMLBlock)
reg.Register(ast.KindList, r.renderList)
reg.Register(ast.KindListItem, r.renderListItem)
reg.Register(ast.KindParagraph, r.renderParagraph)
reg.Register(ast.KindTextBlock, r.renderTextBlock)
reg.Register(ast.KindThematicBreak, r.renderThematicBreak)
// inlines
reg.Register(ast.KindAutoLink, r.renderAutoLink)
reg.Register(ast.KindCodeSpan, r.renderCodeSpan)
reg.Register(ast.KindEmphasis, r.renderEmphasis)
reg.Register(ast.KindImage, r.renderImage)
reg.Register(ast.KindLink, r.renderLink)
reg.Register(ast.KindRawHTML, r.renderRawHTML)
reg.Register(ast.KindText, r.renderText)
reg.Register(ast.KindString, r.renderString)
}
func (r *Renderer) writeLines(w util.BufWriter, source []byte, n ast.Node) {
l := n.Lines().Len()
for i := 0; i < l; i++ {
line := n.Lines().At(i)
r.Writer.RawWrite(w, line.Value(source))
}
}
// GlobalAttributeFilter defines attribute names which any elements can have.
var GlobalAttributeFilter = util.NewBytesFilter(
[]byte("accesskey"),
[]byte("autocapitalize"),
[]byte("autofocus"),
[]byte("class"),
[]byte("contenteditable"),
[]byte("dir"),
[]byte("draggable"),
[]byte("enterkeyhint"),
[]byte("hidden"),
[]byte("id"),
[]byte("inert"),
[]byte("inputmode"),
[]byte("is"),
[]byte("itemid"),
[]byte("itemprop"),
[]byte("itemref"),
[]byte("itemscope"),
[]byte("itemtype"),
[]byte("lang"),
[]byte("part"),
[]byte("role"),
[]byte("slot"),
[]byte("spellcheck"),
[]byte("style"),
[]byte("tabindex"),
[]byte("title"),
[]byte("translate"),
)
func (r *Renderer) renderDocument(
w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
// nothing to do
return ast.WalkContinue, nil
}
// HeadingAttributeFilter defines attribute names which heading elements can have.
var HeadingAttributeFilter = GlobalAttributeFilter
func (r *Renderer) renderHeading(
w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
n := node.(*ast.Heading)
if entering {
_, _ = w.WriteString("<h")
_ = w.WriteByte("0123456"[n.Level])
if n.Attributes() != nil {
RenderAttributes(w, node, HeadingAttributeFilter)
}
_ = w.WriteByte('>')
} else {
_, _ = w.WriteString("</h")
_ = w.WriteByte("0123456"[n.Level])
_, _ = w.WriteString(">\n")
}
return ast.WalkContinue, nil
}
// BlockquoteAttributeFilter defines attribute names which blockquote elements can have.
var BlockquoteAttributeFilter = GlobalAttributeFilter.Extend(
[]byte("cite"),
)
func (r *Renderer) renderBlockquote(
w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
if entering {
if n.Attributes() != nil {
_, _ = w.WriteString("<blockquote")
RenderAttributes(w, n, BlockquoteAttributeFilter)
_ = w.WriteByte('>')
} else {
_, _ = w.WriteString("<blockquote>\n")
}
} else {
_, _ = w.WriteString("</blockquote>\n")
}
return ast.WalkContinue, nil
}
func (r *Renderer) renderCodeBlock(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
if entering {
_, _ = w.WriteString("<pre><code>")
r.writeLines(w, source, n)
} else {
_, _ = w.WriteString("</code></pre>\n")
}
return ast.WalkContinue, nil
}
func (r *Renderer) renderFencedCodeBlock(
w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
n := node.(*ast.FencedCodeBlock)
if entering {
_, _ = w.WriteString("<pre><code")
language := n.Language(source)
if language != nil {
_, _ = w.WriteString(" class=\"language-")
r.Writer.Write(w, language)
_, _ = w.WriteString("\"")
}
_ = w.WriteByte('>')
r.writeLines(w, source, n)
} else {
_, _ = w.WriteString("</code></pre>\n")
}
return ast.WalkContinue, nil
}
func (r *Renderer) renderHTMLBlock(
w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
n := node.(*ast.HTMLBlock)
if entering {
if r.Unsafe {
l := n.Lines().Len()
for i := 0; i < l; i++ {
line := n.Lines().At(i)
r.Writer.SecureWrite(w, line.Value(source))
}
} else {
_, _ = w.WriteString("<!-- raw HTML omitted -->\n")
}
} else {
if n.HasClosure() {
if r.Unsafe {
closure := n.ClosureLine
r.Writer.SecureWrite(w, closure.Value(source))
} else {
_, _ = w.WriteString("<!-- raw HTML omitted -->\n")
}
}
}
return ast.WalkContinue, nil
}
// ListAttributeFilter defines attribute names which list elements can have.
var ListAttributeFilter = GlobalAttributeFilter.Extend(
[]byte("start"),
[]byte("reversed"),
[]byte("type"),
)
func (r *Renderer) renderList(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
n := node.(*ast.List)
tag := "ul"
if n.IsOrdered() {
tag = "ol"
}
if entering {
_ = w.WriteByte('<')
_, _ = w.WriteString(tag)
if n.IsOrdered() && n.Start != 1 {
_, _ = fmt.Fprintf(w, " start=\"%d\"", n.Start)
}
if n.Attributes() != nil {
RenderAttributes(w, n, ListAttributeFilter)
}
_, _ = w.WriteString(">\n")
} else {
_, _ = w.WriteString("</")
_, _ = w.WriteString(tag)
_, _ = w.WriteString(">\n")
}
return ast.WalkContinue, nil
}
// ListItemAttributeFilter defines attribute names which list item elements can have.
var ListItemAttributeFilter = GlobalAttributeFilter.Extend(
[]byte("value"),
)
func (r *Renderer) renderListItem(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
if entering {
if n.Attributes() != nil {
_, _ = w.WriteString("<li")
RenderAttributes(w, n, ListItemAttributeFilter)
_ = w.WriteByte('>')
} else {
_, _ = w.WriteString("<li>")
}
fc := n.FirstChild()
if fc != nil {
if _, ok := fc.(*ast.TextBlock); !ok {
_ = w.WriteByte('\n')
}
}
} else {
_, _ = w.WriteString("</li>\n")
}
return ast.WalkContinue, nil
}
// ParagraphAttributeFilter defines attribute names which paragraph elements can have.
var ParagraphAttributeFilter = GlobalAttributeFilter
func (r *Renderer) renderParagraph(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
if entering {
if n.Attributes() != nil {
_, _ = w.WriteString("<p")
RenderAttributes(w, n, ParagraphAttributeFilter)
_ = w.WriteByte('>')
} else {
_, _ = w.WriteString("<p>")
}
} else {
_, _ = w.WriteString("</p>\n")
}
return ast.WalkContinue, nil
}
func (r *Renderer) renderTextBlock(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
if n.NextSibling() != nil && n.FirstChild() != nil {
_ = w.WriteByte('\n')
}
}
return ast.WalkContinue, nil
}
// ThematicAttributeFilter defines attribute names which hr elements can have.
var ThematicAttributeFilter = GlobalAttributeFilter.Extend(
[]byte("align"), // [Deprecated]
[]byte("color"), // [Not Standardized]
[]byte("noshade"), // [Deprecated]
[]byte("size"), // [Deprecated]
[]byte("width"), // [Deprecated]
)
func (r *Renderer) renderThematicBreak(
w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
return ast.WalkContinue, nil
}
_, _ = w.WriteString("<hr")
if n.Attributes() != nil {
RenderAttributes(w, n, ThematicAttributeFilter)
}
if r.XHTML {
_, _ = w.WriteString(" />\n")
} else {
_, _ = w.WriteString(">\n")
}
return ast.WalkContinue, nil
}
// LinkAttributeFilter defines attribute names which link elements can have.
var LinkAttributeFilter = GlobalAttributeFilter.Extend(
[]byte("download"),
// []byte("href"),
[]byte("hreflang"),
[]byte("media"),
[]byte("ping"),
[]byte("referrerpolicy"),
[]byte("rel"),
[]byte("shape"),
[]byte("target"),
)
func (r *Renderer) renderAutoLink(
w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
n := node.(*ast.AutoLink)
if !entering {
return ast.WalkContinue, nil
}
_, _ = w.WriteString(`<a href="`)
url := n.URL(source)
label := n.Label(source)
if n.AutoLinkType == ast.AutoLinkEmail && !bytes.HasPrefix(bytes.ToLower(url), []byte("mailto:")) {
_, _ = w.WriteString("mailto:")
}
_, _ = w.Write(util.EscapeHTML(util.URLEscape(url, false)))
if n.Attributes() != nil {
_ = w.WriteByte('"')
RenderAttributes(w, n, LinkAttributeFilter)
_ = w.WriteByte('>')
} else {
_, _ = w.WriteString(`">`)
}
_, _ = w.Write(util.EscapeHTML(label))
_, _ = w.WriteString(`</a>`)
return ast.WalkContinue, nil
}
// CodeAttributeFilter defines attribute names which code elements can have.
var CodeAttributeFilter = GlobalAttributeFilter
func (r *Renderer) renderCodeSpan(w util.BufWriter, source []byte, n ast.Node, entering bool) (ast.WalkStatus, error) {
if entering {
if n.Attributes() != nil {
_, _ = w.WriteString("<code")
RenderAttributes(w, n, CodeAttributeFilter)
_ = w.WriteByte('>')
} else {
_, _ = w.WriteString("<code>")
}
for c := n.FirstChild(); c != nil; c = c.NextSibling() {
segment := c.(*ast.Text).Segment
value := segment.Value(source)
if bytes.HasSuffix(value, []byte("\n")) {
r.Writer.RawWrite(w, value[:len(value)-1])
r.Writer.RawWrite(w, []byte(" "))
} else {
r.Writer.RawWrite(w, value)
}
}
return ast.WalkSkipChildren, nil
}
_, _ = w.WriteString("</code>")
return ast.WalkContinue, nil
}
// EmphasisAttributeFilter defines attribute names which emphasis elements can have.
var EmphasisAttributeFilter = GlobalAttributeFilter
func (r *Renderer) renderEmphasis(
w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
n := node.(*ast.Emphasis)
tag := "em"
if n.Level == 2 {
tag = "strong"
}
if entering {
_ = w.WriteByte('<')
_, _ = w.WriteString(tag)
if n.Attributes() != nil {
RenderAttributes(w, n, EmphasisAttributeFilter)
}
_ = w.WriteByte('>')
} else {
_, _ = w.WriteString("</")
_, _ = w.WriteString(tag)
_ = w.WriteByte('>')
}
return ast.WalkContinue, nil
}
func (r *Renderer) renderLink(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
n := node.(*ast.Link)
if entering {
_, _ = w.WriteString("<a href=\"")
if r.Unsafe || !IsDangerousURL(n.Destination) {
_, _ = w.Write(util.EscapeHTML(util.URLEscape(n.Destination, true)))
}
_ = w.WriteByte('"')
if n.Title != nil {
_, _ = w.WriteString(` title="`)
r.Writer.Write(w, n.Title)
_ = w.WriteByte('"')
}
if n.Attributes() != nil {
RenderAttributes(w, n, LinkAttributeFilter)
}
_ = w.WriteByte('>')
} else {
_, _ = w.WriteString("</a>")
}
return ast.WalkContinue, nil
}
// ImageAttributeFilter defines attribute names which image elements can have.
var ImageAttributeFilter = GlobalAttributeFilter.Extend(
[]byte("align"),
[]byte("border"),
[]byte("crossorigin"),
[]byte("decoding"),
[]byte("height"),
[]byte("importance"),
[]byte("intrinsicsize"),
[]byte("ismap"),
[]byte("loading"),
[]byte("referrerpolicy"),
[]byte("sizes"),
[]byte("srcset"),
[]byte("usemap"),
[]byte("width"),
)
func (r *Renderer) renderImage(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
return ast.WalkContinue, nil
}
n := node.(*ast.Image)
_, _ = w.WriteString("<img src=\"")
if r.Unsafe || !IsDangerousURL(n.Destination) {
_, _ = w.Write(util.EscapeHTML(util.URLEscape(n.Destination, true)))
}
_, _ = w.WriteString(`" alt="`)
r.renderAttribute(w, source, n)
_ = w.WriteByte('"')
if n.Title != nil {
_, _ = w.WriteString(` title="`)
r.Writer.Write(w, n.Title)
_ = w.WriteByte('"')
}
if n.Attributes() != nil {
RenderAttributes(w, n, ImageAttributeFilter)
}
if r.XHTML {
_, _ = w.WriteString(" />")
} else {
_, _ = w.WriteString(">")
}
return ast.WalkSkipChildren, nil
}
func (r *Renderer) renderRawHTML(
w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
return ast.WalkSkipChildren, nil
}
if r.Unsafe {
n := node.(*ast.RawHTML)
l := n.Segments.Len()
for i := 0; i < l; i++ {
segment := n.Segments.At(i)
_, _ = w.Write(segment.Value(source))
}
return ast.WalkSkipChildren, nil
}
_, _ = w.WriteString("<!-- raw HTML omitted -->")
return ast.WalkSkipChildren, nil
}
func (r *Renderer) renderText(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
return ast.WalkContinue, nil
}
n := node.(*ast.Text)
segment := n.Segment
if n.IsRaw() {
r.Writer.RawWrite(w, segment.Value(source))
} else {
value := segment.Value(source)
r.Writer.Write(w, value)
if n.HardLineBreak() || (n.SoftLineBreak() && r.HardWraps) {
if r.XHTML {
_, _ = w.WriteString("<br />\n")
} else {
_, _ = w.WriteString("<br>\n")
}
} else if n.SoftLineBreak() {
if r.EastAsianLineBreaks != EastAsianLineBreaksNone && len(value) != 0 {
sibling := node.NextSibling()
if sibling != nil && sibling.Kind() == ast.KindText {
if siblingText := sibling.(*ast.Text).Text(source); len(siblingText) != 0 {
thisLastRune := util.ToRune(value, len(value)-1)
siblingFirstRune, _ := utf8.DecodeRune(siblingText)
if r.EastAsianLineBreaks.softLineBreak(thisLastRune, siblingFirstRune) {
_ = w.WriteByte('\n')
}
}
}
} else {
_ = w.WriteByte('\n')
}
}
}
return ast.WalkContinue, nil
}
func (r *Renderer) renderString(w util.BufWriter, source []byte, node ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
return ast.WalkContinue, nil
}
n := node.(*ast.String)
if n.IsCode() {
_, _ = w.Write(n.Value)
} else {
if n.IsRaw() {
r.Writer.RawWrite(w, n.Value)
} else {
r.Writer.Write(w, n.Value)
}
}
return ast.WalkContinue, nil
}
func (r *Renderer) renderAttribute(w util.BufWriter, source []byte, n ast.Node) {
for c := n.FirstChild(); c != nil; c = c.NextSibling() {
if s, ok := c.(*ast.String); ok {
_, _ = r.renderString(w, source, s, true)
} else if t, ok := c.(*ast.String); ok {
_, _ = r.renderText(w, source, t, true)
} else if !c.HasChildren() {
r.Writer.Write(w, c.Text(source))
if t, ok := c.(*ast.Text); ok && t.SoftLineBreak() {
_ = w.WriteByte('\n')
}
} else {
r.renderAttribute(w, source, c)
}
}
}
var dataPrefix = []byte("data-")
// RenderAttributes renders given node's attributes.
// You can specify attribute names to render by the filter.
// If filter is nil, RenderAttributes renders all attributes.
func RenderAttributes(w util.BufWriter, node ast.Node, filter util.BytesFilter) {
for _, attr := range node.Attributes() {
if filter != nil && !filter.Contains(attr.Name) {
if !bytes.HasPrefix(attr.Name, dataPrefix) {
continue
}
}
_, _ = w.WriteString(" ")
_, _ = w.Write(attr.Name)
_, _ = w.WriteString(`="`)
// TODO: convert numeric values to strings
var value []byte
switch typed := attr.Value.(type) {
case []byte:
value = typed
case string:
value = util.StringToReadOnlyBytes(typed)
}
_, _ = w.Write(util.EscapeHTML(value))
_ = w.WriteByte('"')
}
}
// A Writer interface writes textual contents to a writer.
type Writer interface {
// Write writes the given source to writer with resolving references and unescaping
// backslash escaped characters.
Write(writer util.BufWriter, source []byte)
// RawWrite writes the given source to writer without resolving references and
// unescaping backslash escaped characters.
RawWrite(writer util.BufWriter, source []byte)
// SecureWrite writes the given source to writer with replacing insecure characters.
SecureWrite(writer util.BufWriter, source []byte)
}
var replacementCharacter = []byte("\ufffd")
// A WriterConfig struct has configurations for the HTML based writers.
type WriterConfig struct {
// EscapedSpace is an option that indicates that a '\' escaped half-space(0x20) should not be rendered.
EscapedSpace bool
}
// A WriterOption interface sets options for HTML based writers.
type WriterOption func(*WriterConfig)
// WithEscapedSpace is a WriterOption indicates that a '\' escaped half-space(0x20) should not be rendered.
func WithEscapedSpace() WriterOption {
return func(c *WriterConfig) {
c.EscapedSpace = true
}
}
type defaultWriter struct {
WriterConfig
}
// NewWriter returns a new Writer.
func NewWriter(opts ...WriterOption) Writer {
w := &defaultWriter{}
for _, opt := range opts {
opt(&w.WriterConfig)
}
return w
}
func escapeRune(writer util.BufWriter, r rune) {
if r < 256 {
v := util.EscapeHTMLByte(byte(r))
if v != nil {
_, _ = writer.Write(v)
return
}
}
_, _ = writer.WriteRune(util.ToValidRune(r))
}
func (d *defaultWriter) SecureWrite(writer util.BufWriter, source []byte) {
n := 0
l := len(source)
for i := 0; i < l; i++ {
if source[i] == '\u0000' {
_, _ = writer.Write(source[i-n : i])
n = 0
_, _ = writer.Write(replacementCharacter)
continue
}
n++
}
if n != 0 {
_, _ = writer.Write(source[l-n:])
}
}
func (d *defaultWriter) RawWrite(writer util.BufWriter, source []byte) {
n := 0
l := len(source)
for i := 0; i < l; i++ {
v := util.EscapeHTMLByte(source[i])
if v != nil {
_, _ = writer.Write(source[i-n : i])
n = 0
_, _ = writer.Write(v)
continue
}
n++
}
if n != 0 {
_, _ = writer.Write(source[l-n:])
}
}
func (d *defaultWriter) Write(writer util.BufWriter, source []byte) {
escaped := false
var ok bool
limit := len(source)
n := 0
for i := 0; i < limit; i++ {
c := source[i]
if escaped {
if util.IsPunct(c) {
d.RawWrite(writer, source[n:i-1])
n = i
escaped = false
continue
}
if d.EscapedSpace && c == ' ' {
d.RawWrite(writer, source[n:i-1])
n = i + 1
escaped = false
continue
}
}
if c == '\x00' {
d.RawWrite(writer, source[n:i])
d.RawWrite(writer, replacementCharacter)
n = i + 1
escaped = false
continue
}
if c == '&' {
pos := i
next := i + 1
if next < limit && source[next] == '#' {
nnext := next + 1
if nnext < limit {
nc := source[nnext]
// code point like #x22;
if nnext < limit && nc == 'x' || nc == 'X' {
start := nnext + 1
i, ok = util.ReadWhile(source, [2]int{start, limit}, util.IsHexDecimal)
if ok && i < limit && source[i] == ';' && i-start < 7 {
v, _ := strconv.ParseUint(util.BytesToReadOnlyString(source[start:i]), 16, 32)
d.RawWrite(writer, source[n:pos])
n = i + 1
escapeRune(writer, rune(v))
continue
}
// code point like #1234;
} else if nc >= '0' && nc <= '9' {
start := nnext
i, ok = util.ReadWhile(source, [2]int{start, limit}, util.IsNumeric)
if ok && i < limit && i-start < 8 && source[i] == ';' {
v, _ := strconv.ParseUint(util.BytesToReadOnlyString(source[start:i]), 10, 32)
d.RawWrite(writer, source[n:pos])
n = i + 1
escapeRune(writer, rune(v))
continue
}
}
}
} else {
start := next
i, ok = util.ReadWhile(source, [2]int{start, limit}, util.IsAlphaNumeric)
// entity reference
if ok && i < limit && source[i] == ';' {
name := util.BytesToReadOnlyString(source[start:i])
entity, ok := util.LookUpHTML5EntityByName(name)
if ok {
d.RawWrite(writer, source[n:pos])
n = i + 1
d.RawWrite(writer, entity.Characters)
continue
}
}
}
i = next - 1
}
if c == '\\' {
escaped = true
continue
}
escaped = false
}
d.RawWrite(writer, source[n:])
}
// DefaultWriter is a default instance of the Writer.
var DefaultWriter = NewWriter()
var bDataImage = []byte("data:image/")
var bPng = []byte("png;")
var bGif = []byte("gif;")
var bJpeg = []byte("jpeg;")
var bWebp = []byte("webp;")
var bSvg = []byte("svg+xml;")
var bJs = []byte("javascript:")
var bVb = []byte("vbscript:")
var bFile = []byte("file:")
var bData = []byte("data:")
func hasPrefix(s, prefix []byte) bool {
return len(s) >= len(prefix) && bytes.Equal(bytes.ToLower(s[0:len(prefix)]), bytes.ToLower(prefix))
}
// IsDangerousURL returns true if the given url seems a potentially dangerous url,
// otherwise false.
func IsDangerousURL(url []byte) bool {
if hasPrefix(url, bDataImage) && len(url) >= 11 {
v := url[11:]
if hasPrefix(v, bPng) || hasPrefix(v, bGif) ||
hasPrefix(v, bJpeg) || hasPrefix(v, bWebp) ||
hasPrefix(v, bSvg) {
return false
}
return true
}
return hasPrefix(url, bJs) || hasPrefix(url, bVb) ||
hasPrefix(url, bFile) || hasPrefix(url, bData)
}