Initial commit: svg backend

backend/app/services/svg_inspector.py

@@ -0,0 +1,31 @@
+from defusedxml import ElementTree as DefusedET
+from fastapi import HTTPException, status
+
+from app.core.config import settings
+
+
+def inspect_svg_bytes(content: bytes) -> int:
+    try:
+        root = DefusedET.fromstring(content)
+    except Exception as exc:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail=f"Invalid SVG XML: {exc.__class__.__name__}",
+        ) from exc
+
+    tag = root.tag or ""
+    if not tag.endswith("svg"):
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Root element is not <svg>",
+        )
+
+    element_count = sum(1 for _ in root.iter())
+
+    if element_count > settings.svg_max_elements:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="SVG element count exceeds configured limit",
+        )
+
+    return element_count