1 files changed, 19 insertions, 14 deletions
diff --git a/roseh.moe.go b/roseh.moe.go
index 55e2682..b134de0 100644
--- a/roseh.moe.go
+++ b/roseh.moe.go
@@ -265,15 +265,22 @@ func writeHoleFile(part *multipart.Part) (string, error) {
 	return hole, f.Close()
 }
 
-func decryptedSize(size int64) int64 {
-	size -= 32
-	segments := (size + (blockSize - 1)) / blockSize
-	return size - segments*16
+type offsetReader struct {
+	io.ReadSeeker
+	offset int
+}
+
+func (r *offsetReader) Seek(offset int64, whence int) (int64, error) {
+	if whence == io.SeekStart {
+		offset += int64(r.offset)
+	}
+	n, err := r.ReadSeeker.Seek(offset, whence)
+	return n - int64(r.offset), err
 }
 
 var errNoHole = errors.New("no such hole")
 
-func readHoleFile(w http.ResponseWriter, hole string) error {
+func readHoleFile(w http.ResponseWriter, req *http.Request, hole string) error {
 	key, err := hkdf.Key(sha256.New, []byte(hole), nil, "", 48)
 	if err != nil {
 		return err
@@ -287,10 +294,6 @@ func readHoleFile(w http.ResponseWriter, hole string) error {
 		return err
 	}
 	defer f.Close()
-	stat, err := f.Stat()
-	if err != nil {
-		return err
-	}
 	r := oae2.NewReader(f, encryptionKey, blockSize)
 	buf := make([]byte, 8)
 	if _, err := io.ReadFull(r, buf); err != nil {
@@ -303,10 +306,12 @@ func readHoleFile(w http.ResponseWriter, hole string) error {
 	}
 	fileName := string(buf)
 	w.Header().Set("Content-Disposition", "attachment; filename*=UTF-8''"+fileName)
-	fileSize := decryptedSize(stat.Size()) - 8 - int64(fileNameLen)
-	w.Header().Set("Content-Length", strconv.FormatInt(fileSize, 10))
-	_, err = io.Copy(w, r)
-	return err
+	var modTime time.Time
+	if stat, err := f.Stat(); err == nil {
+		modTime = stat.ModTime()
+	}
+	http.ServeContent(w, req, fileName, modTime, &offsetReader{r, 8 + int(fileNameLen)})
+	return nil
 }
 
 func wormhole(w http.ResponseWriter, r *http.Request) {
@@ -362,7 +367,7 @@ func wormholeUpload(w http.ResponseWriter, r *http.Request) {
 }
 
 func wormholeDownload(w http.ResponseWriter, r *http.Request) {
-	if err := readHoleFile(w, r.PathValue("hole")); err != nil {
+	if err := readHoleFile(w, r, r.PathValue("hole")); err != nil {
 		if err == errNoHole {
 			notFound(w, r)
 			return