Support range requests for wormhole downloads

4 files changed, 23 insertions, 18 deletions

diff --git a/default.nix b/default.nix
index 3f75480..269e821 100644
--- a/default.nix
+++ b/default.nix
@@ -16,5 +16,5 @@ pkgs.buildGoModule rec {
   # remember to bump this hash when your dependencies change.
   # vendorHash = pkgs.lib.fakeHash;
 
-  vendorHash = "sha256-w6HhPvISsk/a6WC/T9Ml02SCZ8LXaTKVp5brPkx7Aec=";
+  vendorHash = "sha256-J5cVBGeQ7lLVd4KMkbwDdpnCckW/t9m1Y2V9Y5PjEIs=";
 }
diff --git a/go.mod b/go.mod
index e3961a9..f41972f 100644
--- a/go.mod
+++ b/go.mod
@@ -6,7 +6,7 @@ require (
 	github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e
 	golang.org/x/term v0.38.0
 	roseh.moe/pkg/ccl v1.0.1
-	roseh.moe/pkg/oae2 v0.0.2
+	roseh.moe/pkg/oae2 v0.1.0
 	roseh.moe/pkg/wordlist v1.0.2
 )
 
diff --git a/go.sum b/go.sum
index 5afb994..f7204d2 100644
--- a/go.sum
+++ b/go.sum
@@ -8,7 +8,7 @@ golang.org/x/term v0.38.0 h1:PQ5pkm/rLO6HnxFR7N2lJHOZX6Kez5Y1gDSJla6jo7Q=
 golang.org/x/term v0.38.0/go.mod h1:bSEAKrOT1W+VSu9TSCMtoGEOUcKxOKgl3LE5QEF/xVg=
 roseh.moe/pkg/ccl v1.0.1 h1:jD8d45xlyB3OphhSI9qoMvKAohyQ2Xtq52NPOnqBWtE=
 roseh.moe/pkg/ccl v1.0.1/go.mod h1:OCcZ30pQDtjXgqgpN8eLo6f/pTi6XVKIHPs1k+gups0=
-roseh.moe/pkg/oae2 v0.0.2 h1:h/anygogeuOAFp9tVDP5RNlEo/n4lEgpyVOe+0QSix8=
-roseh.moe/pkg/oae2 v0.0.2/go.mod h1:SZ5K2nvKreVdhHVNxujxcZLOnjhVi+qPi2XkB18dR8g=
+roseh.moe/pkg/oae2 v0.1.0 h1:mGkGIHErlnykRZZ1dvHd73/gVjPudIEoXxdJ133GKeM=
+roseh.moe/pkg/oae2 v0.1.0/go.mod h1:SZ5K2nvKreVdhHVNxujxcZLOnjhVi+qPi2XkB18dR8g=
 roseh.moe/pkg/wordlist v1.0.2 h1:riB2RqCU5zXfCQjaPHYTXV/688FV9/Bp6Hnb0IAkP9c=
 roseh.moe/pkg/wordlist v1.0.2/go.mod h1:2Jd7j6Qy5SElcrITJJNUcbxH9TPKYn0k+BJL3tsJdiY=
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