refactor: FilterReadMeScripts (#8154 close #8150)

* refactor: FilterReadMeScripts

* .

server/handles/down.go

@@ -1,9 +1,12 @@
 package handles
 
 import (
+	"bytes"
 	"fmt"
 	"io"
+	"net/http"
 	stdpath "path"
+	"strconv"
 	"strings"
 
 	"github.com/alist-org/alist/v3/internal/conf"
@@ -15,7 +18,9 @@ import (
 	"github.com/alist-org/alist/v3/pkg/utils"
 	"github.com/alist-org/alist/v3/server/common"
 	"github.com/gin-gonic/gin"
+	"github.com/microcosm-cc/bluemonday"
 	log "github.com/sirupsen/logrus"
+	"github.com/yuin/goldmark"
 )
 
 func Down(c *gin.Context) {
@@ -124,7 +129,34 @@ func localProxy(c *gin.Context, link *model.Link, file model.Obj, proxyRange boo
 	if proxyRange {
 		common.ProxyRange(link, file.GetSize())
 	}
-	err = common.Proxy(c.Writer, c.Request, link, file)
+
+	//优先处理md文件
+	if utils.Ext(file.GetName()) == "md" && setting.GetBool(conf.FilterReadMeScripts) {
+		w := c.Writer
+		buf := bytes.NewBuffer(make([]byte, 0, file.GetSize()))
+		err = common.Proxy(&proxyResponseWriter{ResponseWriter: w, Writer: buf}, c.Request, link, file)
+		if err == nil && buf.Len() > 0 {
+			if w.Status() < 200 || w.Status() > 300 {
+				w.Write(buf.Bytes())
+				return
+			}
+
+			var html bytes.Buffer
+			if err = goldmark.Convert(buf.Bytes(), &html); err != nil {
+				err = fmt.Errorf("markdown conversion failed: %w", err)
+			} else {
+				buf.Reset()
+				err = bluemonday.UGCPolicy().SanitizeReaderToWriter(&html, buf)
+				if err == nil {
+					w.Header().Set("Content-Length", strconv.FormatInt(int64(buf.Len()), 10))
+					w.Header().Set("Content-Type", "text/html; charset=utf-8")
+					_, err = utils.CopyWithBuffer(c.Writer, buf)
+				}
+			}
+		}
+	} else {
+		err = common.Proxy(c.Writer, c.Request, link, file)
+	}
 	if err != nil {
 		common.ErrorResp(c, err, 500, true)
 		return
@@ -150,3 +182,12 @@ func canProxy(storage driver.Driver, filename string) bool {
 	}
 	return false
 }
+
+type proxyResponseWriter struct {
+	http.ResponseWriter
+	io.Writer
+}
+
+func (pw *proxyResponseWriter) Write(p []byte) (int, error) {
+	return pw.Writer.Write(p)
+}