Add test for attempting empty download

get_test.go

@@ -66,4 +66,28 @@ func TestGet(t *testing.T) {
 			t.Error("expected reader to be closed")
 		}
 	})
+
+	SubTest(t, "EmptyDownload", func(t *testing.T, store *MockFullDataStore) {
+		store.EXPECT().GetInfo("yes").Return(FileInfo{
+			Offset: 0,
+			MetaData: map[string]string{
+				"filename": "file.jpg\"evil",
+			},
+		}, nil)
+
+		handler, _ := NewHandler(Config{
+			DataStore: store,
+		})
+
+		(&httpTest{
+			Method: "GET",
+			URL:    "yes",
+			ResHeader: map[string]string{
+				"Content-Length":      "0",
+				"Content-Disposition": `inline;filename="file.jpg\"evil"`,
+			},
+			Code:    http.StatusNoContent,
+			ResBody: "",
+		}).Run(handler, t)
+	})
 }

unrouted_handler.go

@@ -499,6 +499,12 @@ func (handler *UnroutedHandler) GetFile(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
+	// Set headers before sending responses
+	w.Header().Set("Content-Length", strconv.FormatInt(info.Offset, 10))
+	if filename, ok := info.MetaData["filename"]; ok {
+		w.Header().Set("Content-Disposition", "inline;filename="+strconv.Quote(filename))
+	}
+
 	// Do not do anything if no data is stored yet.
 	if info.Offset == 0 {
 		handler.sendResp(w, r, http.StatusNoContent)
@@ -512,11 +518,6 @@ func (handler *UnroutedHandler) GetFile(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	if filename, ok := info.MetaData["filename"]; ok {
-		w.Header().Set("Content-Disposition", "inline;filename="+strconv.Quote(filename))
-	}
-
-	w.Header().Set("Content-Length", strconv.FormatInt(info.Offset, 10))
 	handler.sendResp(w, r, http.StatusOK)
 	io.Copy(w, src)