Sanitize cross-platform media filenames

app/services/validator.py

@@ -9,44 +9,11 @@ from app.core.config import Settings
 from app.core.exceptions import InputError
 
 MEDIA_EXTENSIONS = {
-    ".3gp",
-    ".aac",
-    ".aiff",
-    ".apng",
-    ".avi",
-    ".bin",
-    ".bmp",
-    ".flac",
-    ".gif",
-    ".heic",
-    ".jpeg",
-    ".jpg",
-    ".m4a",
-    ".m4v",
-    ".mkv",
-    ".m3u",
-    ".m3u8",
-    ".mov",
-    ".mp3",
-    ".mp4",
-    ".mpeg",
-    ".mpg",
-    ".oga",
-    ".ogg",
-    ".opus",
-    ".png",
-    ".svg",
-    ".tif",
-    ".tiff",
-    ".ts",
-    ".vtt",
-    ".wav",
-    ".webm",
-    ".webp",
-    ".wmv",
-    ".srt",
-    ".ass",
-    ".ssa",
+    ".3gp", ".aac", ".aiff", ".apng", ".avi", ".bin", ".bmp", ".flac",
+    ".gif", ".heic", ".jpeg", ".jpg", ".m4a", ".m4v", ".mkv", ".m3u",
+    ".m3u8", ".mov", ".mp3", ".mp4", ".mpeg", ".mpg", ".oga", ".ogg",
+    ".opus", ".png", ".svg", ".tif", ".tiff", ".ts", ".vtt", ".wav",
+    ".webm", ".webp", ".wmv", ".srt", ".ass", ".ssa",
 }
 
 
@@ -55,8 +22,16 @@ class MediaValidator:
         self.settings = settings
 
     def safe_filename(self, filename: str | None, fallback: str = "input.bin") -> str:
-        name = Path(filename or fallback).name.replace("\x00", "")
-        if not name or name in {".", ".."}:
+        # Treat both POSIX and Windows separators as path delimiters regardless
+        # of the server OS; never allow a client path to become a stored name.
+        raw = str(filename or fallback).replace("\\", "/")
+        name = raw.rsplit("/", 1)[-1].replace("\x00", "")
+        if (
+            not name
+            or name in {".", ".."}
+            or any(ord(char) < 32 or ord(char) == 127 for char in name)
+            or '"' in name
+        ):
             raise InputError("Invalid filename")
         return name[:240]
 
@@ -72,22 +47,15 @@ class MediaValidator:
         if suffix and suffix not in MEDIA_EXTENSIONS:
             raise InputError("Unsupported media file extension", details={"extension": suffix})
         normalized_mime = mime_type.split(";", 1)[0].lower()
-        allowed = normalized_mime.startswith(
-            ("audio/", "video/", "image/", "text/")
-        ) or normalized_mime in {
-            "application/octet-stream",
-            "application/x-subrip",
-            "application/vnd.apple.mpegurl",
-            "application/x-mpegurl",
+        allowed = normalized_mime.startswith(("audio/", "video/", "image/", "text/")) or normalized_mime in {
+            "application/octet-stream", "application/x-subrip",
+            "application/vnd.apple.mpegurl", "application/x-mpegurl",
         }
         if normalized_mime and not allowed:
             raise InputError("Unsupported media MIME type", details={"mime_type": mime_type})
 
     def validate_probe(self, metadata: dict[str, Any]) -> None:
-        streams = [
-            *(metadata.get("video_streams") or []),
-            *(metadata.get("audio_streams") or []),
-        ]
+        streams = [*(metadata.get("video_streams") or []), *(metadata.get("audio_streams") or [])]
         if not streams:
             raise InputError("The input has no decodable video or audio stream")
         for stream in streams: