forgejo-federation/vendor/github.com/yuin/goldmark/renderer/html/html.go
2020-07-30 12:27:23 -04:00

804 lines
21 KiB
Go
Vendored

package html
import (
"bytes"
"fmt"
"strconv"
"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
XHTML bool
Unsafe bool
}
// NewConfig returns a new Config with defaults.
func NewConfig() Config {
return Config{
Writer: DefaultWriter,
HardWraps: false,
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 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{}
}
// 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("class"),
[]byte("contenteditable"),
[]byte("contextmenu"),
[]byte("dir"),
[]byte("draggable"),
[]byte("dropzone"),
[]byte("hidden"),
[]byte("id"),
[]byte("itemprop"),
[]byte("lang"),
[]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)
_, _ = w.Write(line.Value(source))
}
} else {
_, _ = w.WriteString("<!-- raw HTML omitted -->\n")
}
} else {
if n.HasClosure() {
if r.Unsafe {
closure := n.ClosureLine
_, _ = w.Write(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"),
)
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 _, ok := n.NextSibling().(ast.Node); ok && 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])
if c != n.LastChild() {
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="`)
_, _ = w.Write(util.EscapeHTML(n.Text(source)))
_ = 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 {
r.Writer.Write(w, segment.Value(source))
if n.HardLineBreak() || (n.SoftLineBreak() && r.HardWraps) {
if r.XHTML {
_, _ = w.WriteString("<br />\n")
} else {
_, _ = w.WriteString("<br>\n")
}
} else if n.SoftLineBreak() {
_ = 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
}
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
_, _ = w.Write(util.EscapeHTML(attr.Value.([]byte)))
_ = 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)
}
type defaultWriter struct {
}
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) 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 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] == ';' {
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]), 0, 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 implementation of the Writer.
var DefaultWriter = &defaultWriter{}
var bDataImage = []byte("data:image/")
var bPng = []byte("png;")
var bGif = []byte("gif;")
var bJpeg = []byte("jpeg;")
var bWebp = []byte("webp;")
var bJs = []byte("javascript:")
var bVb = []byte("vbscript:")
var bFile = []byte("file:")
var bData = []byte("data:")
// IsDangerousURL returns true if the given url seems a potentially dangerous url,
// otherwise false.
func IsDangerousURL(url []byte) bool {
if bytes.HasPrefix(url, bDataImage) && len(url) >= 11 {
v := url[11:]
if bytes.HasPrefix(v, bPng) || bytes.HasPrefix(v, bGif) ||
bytes.HasPrefix(v, bJpeg) || bytes.HasPrefix(v, bWebp) {
return false
}
return true
}
return bytes.HasPrefix(url, bJs) || bytes.HasPrefix(url, bVb) ||
bytes.HasPrefix(url, bFile) || bytes.HasPrefix(url, bData)
}