feat: file proxy handle

server/common/sign.go

@@ -0,0 +1,13 @@
+package common
+
+import (
+	"github.com/alist-org/alist/v3/internal/model"
+	"github.com/alist-org/alist/v3/internal/sign"
+)
+
+func Sign(obj model.Obj) string {
+	if obj.IsDir() {
+		return ""
+	}
+	return sign.Sign(obj.GetName())
+}