forgejo-federation/modules/markup/markdown/markdown.go
KN4CK3R c9c7afda1a
Add sanitizer rules per renderer (#16110)
* Added sanitizer rules per renderer.

* Updated documentation.

Co-authored-by: techknowlogick <techknowlogick@gitea.io>
2021-06-23 17:09:51 -04:00

297 lines
7.7 KiB
Go

// Copyright 2014 The Gogs Authors. All rights reserved.
// Copyright 2018 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package markdown
import (
"fmt"
"io"
"io/ioutil"
"strings"
"sync"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/markup"
"code.gitea.io/gitea/modules/markup/common"
"code.gitea.io/gitea/modules/setting"
giteautil "code.gitea.io/gitea/modules/util"
chromahtml "github.com/alecthomas/chroma/formatters/html"
"github.com/yuin/goldmark"
highlighting "github.com/yuin/goldmark-highlighting"
meta "github.com/yuin/goldmark-meta"
"github.com/yuin/goldmark/extension"
"github.com/yuin/goldmark/parser"
"github.com/yuin/goldmark/renderer"
"github.com/yuin/goldmark/renderer/html"
"github.com/yuin/goldmark/util"
)
var converter goldmark.Markdown
var once = sync.Once{}
var urlPrefixKey = parser.NewContextKey()
var isWikiKey = parser.NewContextKey()
var renderMetasKey = parser.NewContextKey()
type closesWithError interface {
io.WriteCloser
CloseWithError(err error) error
}
type limitWriter struct {
w closesWithError
sum int64
limit int64
}
// Write implements the standard Write interface:
func (l *limitWriter) Write(data []byte) (int, error) {
leftToWrite := l.limit - l.sum
if leftToWrite < int64(len(data)) {
n, err := l.w.Write(data[:leftToWrite])
l.sum += int64(n)
if err != nil {
return n, err
}
_ = l.w.Close()
return n, fmt.Errorf("Rendered content too large - truncating render")
}
n, err := l.w.Write(data)
l.sum += int64(n)
return n, err
}
// Close closes the writer
func (l *limitWriter) Close() error {
return l.w.Close()
}
// CloseWithError closes the writer
func (l *limitWriter) CloseWithError(err error) error {
return l.w.CloseWithError(err)
}
// newParserContext creates a parser.Context with the render context set
func newParserContext(ctx *markup.RenderContext) parser.Context {
pc := parser.NewContext(parser.WithIDs(newPrefixedIDs()))
pc.Set(urlPrefixKey, ctx.URLPrefix)
pc.Set(isWikiKey, ctx.IsWiki)
pc.Set(renderMetasKey, ctx.Metas)
return pc
}
// actualRender renders Markdown to HTML without handling special links.
func actualRender(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
once.Do(func() {
converter = goldmark.New(
goldmark.WithExtensions(extension.Table,
extension.Strikethrough,
extension.TaskList,
extension.DefinitionList,
common.FootnoteExtension,
highlighting.NewHighlighting(
highlighting.WithFormatOptions(
chromahtml.WithClasses(true),
chromahtml.PreventSurroundingPre(true),
),
highlighting.WithWrapperRenderer(func(w util.BufWriter, c highlighting.CodeBlockContext, entering bool) {
if entering {
language, _ := c.Language()
if language == nil {
language = []byte("text")
}
languageStr := string(language)
preClasses := []string{}
if languageStr == "mermaid" {
preClasses = append(preClasses, "is-loading")
}
if len(preClasses) > 0 {
_, err := w.WriteString(`<pre class="` + strings.Join(preClasses, " ") + `">`)
if err != nil {
return
}
} else {
_, err := w.WriteString(`<pre>`)
if err != nil {
return
}
}
// include language-x class as part of commonmark spec
_, err := w.WriteString(`<code class="chroma language-` + string(language) + `">`)
if err != nil {
return
}
} else {
_, err := w.WriteString("</code></pre>")
if err != nil {
return
}
}
}),
),
meta.Meta,
),
goldmark.WithParserOptions(
parser.WithAttribute(),
parser.WithAutoHeadingID(),
parser.WithASTTransformers(
util.Prioritized(&ASTTransformer{}, 10000),
),
),
goldmark.WithRendererOptions(
html.WithUnsafe(),
),
)
// Override the original Tasklist renderer!
converter.Renderer().AddOptions(
renderer.WithNodeRenderers(
util.Prioritized(NewHTMLRenderer(), 10),
),
)
})
rd, wr := io.Pipe()
defer func() {
_ = rd.Close()
_ = wr.Close()
}()
lw := &limitWriter{
w: wr,
limit: setting.UI.MaxDisplayFileSize * 3,
}
// FIXME: should we include a timeout that closes the pipe to abort the renderer and sanitizer if it takes too long?
go func() {
defer func() {
err := recover()
if err == nil {
return
}
log.Warn("Unable to render markdown due to panic in goldmark: %v", err)
if log.IsDebug() {
log.Debug("Panic in markdown: %v\n%s", err, string(log.Stack(2)))
}
_ = lw.CloseWithError(fmt.Errorf("%v", err))
}()
// FIXME: Don't read all to memory, but goldmark doesn't support
pc := newParserContext(ctx)
buf, err := ioutil.ReadAll(input)
if err != nil {
log.Error("Unable to ReadAll: %v", err)
return
}
if err := converter.Convert(giteautil.NormalizeEOL(buf), lw, parser.WithContext(pc)); err != nil {
log.Error("Unable to render: %v", err)
_ = lw.CloseWithError(err)
return
}
_ = lw.Close()
}()
buf := markup.SanitizeReader(rd, "")
_, err := io.Copy(output, buf)
return err
}
func render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
defer func() {
err := recover()
if err == nil {
return
}
log.Warn("Unable to render markdown due to panic in goldmark - will return sanitized raw bytes")
if log.IsDebug() {
log.Debug("Panic in markdown: %v\n%s", err, string(log.Stack(2)))
}
ret := markup.SanitizeReader(input, "")
_, err = io.Copy(output, ret)
if err != nil {
log.Error("SanitizeReader failed: %v", err)
}
}()
return actualRender(ctx, input, output)
}
var (
// MarkupName describes markup's name
MarkupName = "markdown"
)
func init() {
markup.RegisterRenderer(Renderer{})
}
// Renderer implements markup.Renderer
type Renderer struct{}
// Name implements markup.Renderer
func (Renderer) Name() string {
return MarkupName
}
// NeedPostProcess implements markup.Renderer
func (Renderer) NeedPostProcess() bool { return true }
// Extensions implements markup.Renderer
func (Renderer) Extensions() []string {
return setting.Markdown.FileExtensions
}
// SanitizerRules implements markup.Renderer
func (Renderer) SanitizerRules() []setting.MarkupSanitizerRule {
return []setting.MarkupSanitizerRule{}
}
// Render implements markup.Renderer
func (Renderer) Render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
return render(ctx, input, output)
}
// Render renders Markdown to HTML with all specific handling stuff.
func Render(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
if ctx.Filename == "" {
ctx.Filename = "a.md"
}
return markup.Render(ctx, input, output)
}
// RenderString renders Markdown string to HTML with all specific handling stuff and return string
func RenderString(ctx *markup.RenderContext, content string) (string, error) {
var buf strings.Builder
if err := Render(ctx, strings.NewReader(content), &buf); err != nil {
return "", err
}
return buf.String(), nil
}
// RenderRaw renders Markdown to HTML without handling special links.
func RenderRaw(ctx *markup.RenderContext, input io.Reader, output io.Writer) error {
return render(ctx, input, output)
}
// RenderRawString renders Markdown to HTML without handling special links and return string
func RenderRawString(ctx *markup.RenderContext, content string) (string, error) {
var buf strings.Builder
if err := RenderRaw(ctx, strings.NewReader(content), &buf); err != nil {
return "", err
}
return buf.String(), nil
}
// IsMarkdownFile reports whether name looks like a Markdown file
// based on its extension.
func IsMarkdownFile(name string) bool {
return markup.IsMarkupFile(name, MarkupName)
}