Fix external render, make iframe render work (#35727, #35730) (#35731)

Backport #35727 and #35730

---------

Signed-off-by: wxiaoguang <wxiaoguang@gmail.com>

routers/web/repo/render.go

@@ -4,18 +4,13 @@
 package repo
 
 import (
-	"bytes"
-	"io"
 	"net/http"
 	"path"
 
 	"code.gitea.io/gitea/models/renderhelper"
-	"code.gitea.io/gitea/modules/charset"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/markup"
-	"code.gitea.io/gitea/modules/typesniffer"
-	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/services/context"
 )
 
@@ -44,22 +39,8 @@ func RenderFile(ctx *context.Context) {
 	}
 	defer dataRc.Close()
 
-	buf := make([]byte, 1024)
-	n, _ := util.ReadAtMost(dataRc, buf)
-	buf = buf[:n]
-
-	st := typesniffer.DetectContentType(buf)
-	isTextFile := st.IsText()
-
-	rd := charset.ToUTF8WithFallbackReader(io.MultiReader(bytes.NewReader(buf), dataRc), charset.ConvertOpts{})
-	ctx.Resp.Header().Add("Content-Security-Policy", "frame-src 'self'; sandbox allow-scripts")
-
 	if markupType := markup.DetectMarkupTypeByFileName(blob.Name()); markupType == "" {
-		if isTextFile {
-			_, _ = io.Copy(ctx.Resp, rd)
-		} else {
-			http.Error(ctx.Resp, "Unsupported file type render", http.StatusInternalServerError)
-		}
+		http.Error(ctx.Resp, "Unsupported file type render", http.StatusBadRequest)
 		return
 	}
 
@@ -68,7 +49,29 @@ func RenderFile(ctx *context.Context) {
 		CurrentTreePath: path.Dir(ctx.Repo.TreePath),
 	}).WithRelativePath(ctx.Repo.TreePath).WithInStandalonePage(true)
 
-	err = markup.Render(rctx, rd, ctx.Resp)
+	renderer, err := markup.FindRendererByContext(rctx)
+	if err != nil {
+		http.Error(ctx.Resp, "Unable to find renderer", http.StatusBadRequest)
+		return
+	}
+
+	extRenderer, ok := renderer.(markup.ExternalRenderer)
+	if !ok {
+		http.Error(ctx.Resp, "Unable to get external renderer", http.StatusBadRequest)
+		return
+	}
+
+	// To render PDF in iframe, the sandbox must NOT be used (iframe & CSP header).
+	// Chrome blocks the PDF rendering when sandboxed, even if all "allow-*" are set.
+	// HINT: PDF-RENDER-SANDBOX: PDF won't render in sandboxed context
+	extRendererOpts := extRenderer.GetExternalRendererOptions()
+	if extRendererOpts.ContentSandbox != "" {
+		ctx.Resp.Header().Add("Content-Security-Policy", "frame-src 'self'; sandbox "+extRendererOpts.ContentSandbox)
+	} else {
+		ctx.Resp.Header().Add("Content-Security-Policy", "frame-src 'self'")
+	}
+
+	err = markup.RenderWithRenderer(rctx, renderer, dataRc, ctx.Resp)
 	if err != nil {
 		log.Error("Failed to render file %q: %v", ctx.Repo.TreePath, err)
 		http.Error(ctx.Resp, "Failed to render file", http.StatusInternalServerError)

routers/web/repo/view.go

@@ -151,17 +151,28 @@ func loadLatestCommitData(ctx *context.Context, latestCommit *git.Commit) bool {
 }
 
 func markupRender(ctx *context.Context, renderCtx *markup.RenderContext, input io.Reader) (escaped *charset.EscapeStatus, output template.HTML, err error) {
+	renderer, err := markup.FindRendererByContext(renderCtx)
+	if err != nil {
+		return nil, "", err
+	}
+
 	markupRd, markupWr := io.Pipe()
 	defer markupWr.Close()
+
 	done := make(chan struct{})
 	go func() {
 		sb := &strings.Builder{}
-		// We allow NBSP here this is rendered
-		escaped, _ = charset.EscapeControlReader(markupRd, sb, ctx.Locale, charset.RuneNBSP)
+		if markup.RendererNeedPostProcess(renderer) {
+			escaped, _ = charset.EscapeControlReader(markupRd, sb, ctx.Locale, charset.RuneNBSP) // We allow NBSP here this is rendered
+		} else {
+			escaped = &charset.EscapeStatus{}
+			_, _ = io.Copy(sb, markupRd)
+		}
 		output = template.HTML(sb.String())
 		close(done)
 	}()
-	err = markup.Render(renderCtx, input, markupWr)
+
+	err = markup.RenderWithRenderer(renderCtx, renderer, input, markupWr)
 	_ = markupWr.CloseWithError(err)
 	<-done
 	return escaped, output, err