Add ParsingError handling for invalid base64

3 files changed, 18 insertions, 16 deletions

diff --git a/snekbox/api/resources/eval.py b/snekbox/api/resources/eval.py
index 764cc0b..de54564 100644
--- a/snekbox/api/resources/eval.py
+++ b/snekbox/api/resources/eval.py
@@ -9,7 +9,7 @@ from snekbox.nsjail import NsJail
 
 __all__ = ("EvalResource",)
 
-from snekbox.snekio import FileAttachment, IllegalPathError
+from snekbox.snekio import FileAttachment, ParsingError
 
 log = logging.getLogger(__name__)
 
@@ -35,7 +35,7 @@ class EvalResource:
                     "properties": {
                         "path": {
                             "type": "string",
-                            # Disallow single forward slashes, absolute paths, and null bytes
+                            # Disallow single absolute paths, and null bytes
                             "pattern": r"^[^/\\0].*",
                         },
                         "content": {"type": "string"},
@@ -110,10 +110,8 @@ class EvalResource:
                 py_args=req.media["args"],
                 files=[FileAttachment.from_dict(file) for file in req.media.get("files", [])],
             )
-        except IllegalPathError as e:
-            raise falcon.HTTPBadRequest(
-                title="Request file path failed validation", description=str(e)
-            )
+        except ParsingError as e:
+            raise falcon.HTTPBadRequest(title="Request file is invalid", description=str(e))
         except Exception:
             log.exception("An exception occurred while trying to process the request")
             raise falcon.HTTPInternalServerError
diff --git a/snekbox/snekio.py b/snekbox/snekio.py
index 2d2de6e..f57d3b0 100644
--- a/snekbox/snekio.py
+++ b/snekbox/snekio.py
@@ -28,16 +28,12 @@ def safe_path(path: str) -> str:
     return path
 
 
-class AttachmentError(ValueError):
-    """Raised when an attachment is invalid."""
-
-
-class ParsingError(AttachmentError):
-    """Raised when an incoming file cannot be parsed."""
+class ParsingError(ValueError):
+    """Raised when an incoming content cannot be parsed."""
 
 
 class IllegalPathError(ParsingError):
-    """Raised when an attachment has an illegal path."""
+    """Raised when a request file has an illegal path."""
 
 
 @dataclass(frozen=True)
@@ -49,9 +45,17 @@ class FileAttachment:
 
     @classmethod
     def from_dict(cls, data: dict[str, str]) -> FileAttachment:
-        """Convert a dict to an attachment."""
+        """
+        Convert a dict to an attachment.
+
+        Raises:
+            ParsingError: Raised when the dict has invalid base64 `content`.
+        """
         path = safe_path(data["path"])
-        content = b64decode(data.get("content", ""))
+        try:
+            content = b64decode(data.get("content", ""))
+        except (TypeError, ValueError) as e:
+            raise ParsingError(f"Invalid base64 encoding for file '{path}'") from e
         return cls(path, content)
 
     @classmethod
diff --git a/tests/api/test_eval.py b/tests/api/test_eval.py
index 41bdd35..64d7ba6 100644
--- a/tests/api/test_eval.py
+++ b/tests/api/test_eval.py
@@ -72,7 +72,7 @@ class TestEvalResource(SnekAPITestCase):
                 result = self.simulate_post(self.PATH, json=body)
                 self.assertEqual(result.status_code, 400)
                 expected = {
-                    "title": "Request file path failed validation",
+                    "title": "Request file is invalid",
                     "description": f"File path '{path}' may not traverse beyond root",
                 }
                 self.assertEqual(expected, result.json)