[bugfix] Use custom blackfriday renderer to only add mention/hashtag links in normal text (#787)

* Use custom blackfriday renderer to only add mention/hashtag links in normal text

* Add additional markdown tests

2 files changed, 60 insertions, 7 deletions

diff --git a/internal/text/markdown.go b/internal/text/markdown.go
index 13fb93378..1382cbf61 100644
--- a/internal/text/markdown.go
+++ b/internal/text/markdown.go
@@ -19,7 +19,9 @@
 package text
 
 import (
+	"bytes"
 	"context"
+	"io"
 
 	"github.com/russross/blackfriday/v2"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
@@ -33,18 +35,51 @@ var (
 	m            *minify.M
 )
 
+type renderer struct {
+	f        *formatter
+	ctx      context.Context
+	mentions []*gtsmodel.Mention
+	tags     []*gtsmodel.Tag
+	blackfriday.HTMLRenderer
+}
+
+func (r *renderer) RenderNode(w io.Writer, node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
+	if node.Type == blackfriday.Text {
+		// call RenderNode to do the html escaping
+		var buff bytes.Buffer
+		status := r.HTMLRenderer.RenderNode(&buff, node, entering)
+
+		html := buff.String()
+		html = r.f.ReplaceTags(r.ctx, html, r.tags)
+		html = r.f.ReplaceMentions(r.ctx, html, r.mentions)
+
+		// we don't have much recourse if this fails
+		_, err := io.WriteString(w, html)
+		if err != nil {
+			log.Errorf("error outputting markdown text: %s", err)
+		}
+		return status
+	}
+	return r.HTMLRenderer.RenderNode(w, node, entering)
+}
+
 func (f *formatter) FromMarkdown(ctx context.Context, md string, mentions []*gtsmodel.Mention, tags []*gtsmodel.Tag) string {
-	// format tags nicely
-	content := f.ReplaceTags(ctx, md, tags)
 
-	// format mentions nicely
-	content = f.ReplaceMentions(ctx, content, mentions)
+	renderer := &renderer{
+		f:        f,
+		ctx:      ctx,
+		mentions: mentions,
+		tags:     tags,
+		HTMLRenderer: *blackfriday.NewHTMLRenderer(blackfriday.HTMLRendererParameters{
+			Flags: blackfriday.CommonHTMLFlags,
+		}),
+	}
 
-	// parse markdown
-	contentBytes := blackfriday.Run([]byte(content), blackfriday.WithExtensions(bfExtensions))
+	// parse markdown, use custom renderer to add hashtag/mention links
+	contentBytes := blackfriday.Run([]byte(md), blackfriday.WithExtensions(bfExtensions), blackfriday.WithRenderer(renderer))
 
 	// clean anything dangerous out of it
-	content = SanitizeHTML(string(contentBytes))
+	content := SanitizeHTML(string(contentBytes))
 
 	if m == nil {
 		m = minify.New()
diff --git a/internal/text/markdown_test.go b/internal/text/markdown_test.go
index 3e156f43e..4c9483c7e 100644
--- a/internal/text/markdown_test.go
+++ b/internal/text/markdown_test.go
@@ -65,6 +65,10 @@ const (
 	mdWithFootnoteExpected          = "<p>fox mulder,fbi.<sup id=\"fnref:1\"><a href=\"#fn:1\" rel=\"nofollow noreferrer\">1</a></sup></p><div><hr><ol><li id=\"fn:1\">federated bureau of investigation<br></li></ol></div>"
 	mdWithBlockQuote                = "get ready, there's a block quote coming:\n\n>line1\n>line2\n>\n>line3\n\n"
 	mdWithBlockQuoteExpected        = "<p>get ready, there’s a block quote coming:</p><blockquote><p>line1<br>line2</p><p>line3</p></blockquote>"
+	mdHashtagAndCodeBlock           = "#Hashtag\n\n```\n#Hashtag\n```"
+	mdHashtagAndCodeBlockExpected   = "<p><a href=\"http://localhost:8080/tags/Hashtag\" class=\"mention hashtag\" rel=\"tag nofollow noreferrer noopener\" target=\"_blank\">#<span>Hashtag</span></a></p><pre><code>#Hashtag\n</code></pre>"
+	mdMentionAndCodeBlock           = "@the_mighty_zork\n\n```\n@the_mighty_zork\n```"
+	mdMentionAndCodeBlockExpected   = "<p><span class=\"h-card\"><a href=\"http://localhost:8080/@the_mighty_zork\" class=\"u-url mention\" rel=\"nofollow noreferrer noopener\" target=\"_blank\">@<span>the_mighty_zork</span></a></span></p><pre><code>@the_mighty_zork\n</code></pre>"
 )
 
 type MarkdownTestSuite struct {
@@ -133,6 +137,20 @@ func (suite *MarkdownTestSuite) TestParseWithBlockquote() {
 	suite.Equal(mdWithBlockQuoteExpected, s)
 }
 
+func (suite *MarkdownTestSuite) TestParseHashtagWithCodeBlock() {
+	s := suite.formatter.FromMarkdown(context.Background(), mdHashtagAndCodeBlock, nil, []*gtsmodel.Tag{
+		suite.testTags["Hashtag"],
+	})
+	suite.Equal(mdHashtagAndCodeBlockExpected, s)
+}
+
+func (suite *MarkdownTestSuite) TestParseMentionWithCodeBlock() {
+	s := suite.formatter.FromMarkdown(context.Background(), mdMentionAndCodeBlock, []*gtsmodel.Mention{
+		suite.testMentions["local_user_2_mention_zork"],
+	}, nil)
+	suite.Equal(mdMentionAndCodeBlockExpected, s)
+}
+
 func TestMarkdownTestSuite(t *testing.T) {
 	suite.Run(t, new(MarkdownTestSuite))
 }