Do more proper path validation for playlist generation

src/main.rs

@@ -199,8 +199,8 @@ async fn stream_video(
     println!("Playlist: {}", playlist);
 
     // Extract video playlist dir to dotenv
-    if !playlist.starts_with("tmp") || playlist.contains("..") {
-        HttpResponse::NotFound().finish()
+    if !playlist.starts_with("tmp") && is_valid_path(playlist) != None {
+        HttpResponse::BadRequest().finish()
     } else if let Ok(file) = NamedFile::open(playlist) {
         file.into_response(&request).unwrap()
     } else {