forgejo/modules/markup/markdown/callout/github_legacy.go
Gusted efd63ec1d8
[BUG] Don't panic on empty blockquote
- On a empty blockquote the callout feature would panic, as it expects
to always have at least one child.
- This panic cannot result in a DoS, because any panic that happens
while rendering any markdown input will be recovered gracefully.
- Adds a simple condition to avoid this panic.
2024-07-21 01:10:20 +02:00

71 lines
2.3 KiB
Go

// Copyright 2019 The Gitea Authors. All rights reserved.
// Copyright 2024 The Forgejo Authors c/o Codeberg e.V.. All rights reserved.
// SPDX-License-Identifier: MIT
package callout
import (
"strings"
"github.com/yuin/goldmark/ast"
"github.com/yuin/goldmark/parser"
"github.com/yuin/goldmark/text"
)
// Transformer for GitHub's legacy callout markup.
type GitHubLegacyCalloutTransformer struct{}
func (g *GitHubLegacyCalloutTransformer) Transform(node *ast.Document, reader text.Reader, pc parser.Context) {
supportedCalloutTypes := map[string]bool{"Note": true, "Warning": true}
_ = ast.Walk(node, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
if !entering {
return ast.WalkContinue, nil
}
switch v := n.(type) {
case *ast.Blockquote:
if v.ChildCount() == 0 {
return ast.WalkContinue, nil
}
// The first paragraph contains the callout type.
firstParagraph := v.FirstChild()
if firstParagraph.ChildCount() < 1 {
return ast.WalkContinue, nil
}
// In the legacy GitHub callout markup, the first node of the first
// paragraph should be an emphasis.
calloutNode, ok := firstParagraph.FirstChild().(*ast.Emphasis)
if !ok {
return ast.WalkContinue, nil
}
calloutText := string(calloutNode.Text(reader.Source()))
calloutType := strings.ToLower(calloutText)
// We only support "Note" and "Warning" callouts in legacy mode,
// match only those.
if _, has := supportedCalloutTypes[calloutText]; !has {
return ast.WalkContinue, nil
}
// Set the attention attribute on the emphasis
calloutNode.SetAttributeString("class", []byte("attention-"+calloutType))
// color the blockquote
v.SetAttributeString("class", []byte("attention-header attention-"+calloutType))
// Create new paragraph.
attentionParagraph := ast.NewParagraph()
attentionParagraph.SetAttributeString("class", []byte("attention-title"))
// Move the callout node to the paragraph and insert the paragraph.
attentionParagraph.AppendChild(attentionParagraph, NewAttention(calloutType))
attentionParagraph.AppendChild(attentionParagraph, calloutNode)
firstParagraph.Parent().InsertBefore(firstParagraph.Parent(), firstParagraph, attentionParagraph)
firstParagraph.RemoveChild(firstParagraph, calloutNode)
}
return ast.WalkContinue, nil
})
}