Harden failure property providers

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 26daf565-a1f4-4bf0-9540-b57f31a4a12b

Author: andystaples

durabletask/internal/helpers.py

@@ -223,16 +223,33 @@ def new_failure_details(
     inner: BaseException | None = ex.__cause__ or ex.__context__
     if len(_visited) > 10 or (inner and id(inner) in _visited) or not isinstance(inner, Exception):
         inner = None
-    properties = None
+    properties: dict[str, struct_pb2.Value] | None = None
     if exception_properties_provider is not None:
         try:
-            properties = exception_properties_provider.get_exception_properties(ex)
+            provider_properties = exception_properties_provider.get_exception_properties(ex)
         except Exception:
             if logger is not None:
                 logger.warning(
                     "ExceptionPropertiesProvider failed while processing %s.",
                     get_qualified_name(type(ex)),
                     exc_info=True)
+        else:
+            try:
+                if provider_properties is not None:
+                    if not isinstance(provider_properties, Mapping):
+                        raise TypeError(
+                            "ExceptionPropertiesProvider.get_exception_properties() "
+                            "must return a mapping or None.")
+                    properties = {
+                        str(key): protobuf_value_from_python(value)
+                        for key, value in cast(Mapping[Any, Any], provider_properties).items()
+                    }
+            except Exception:
+                if logger is not None:
+                    logger.warning(
+                        "ExceptionPropertiesProvider returned invalid properties for %s.",
+                        get_qualified_name(type(ex)),
+                        exc_info=True)
 
     failure_details = pb.TaskFailureDetails(
         errorType=get_qualified_name(type(ex)),
@@ -244,8 +261,8 @@ def new_failure_details(
             if inner else None)
     )
     if properties:
-        for key, value in cast(Mapping[Any, Any], properties).items():
-            failure_details.properties[str(key)].CopyFrom(protobuf_value_from_python(value))
+        for key, value in properties.items():
+            failure_details.properties[key].CopyFrom(value)
     return failure_details
 
 

tests/durabletask/entities/test_entity_failure_handling.py

@@ -163,6 +163,7 @@ def test_orchestrator(ctx: task.OrchestrationContext, _):
         except task.TaskFailedError as error:
             assert error.details.properties is not None
             return error.details.properties
+        return None
 
     with worker.TaskHubGrpcWorker(
             host_address=HOST,

tests/durabletask/test_failure_details.py

@@ -225,6 +225,19 @@ def get_exception_properties(self, exception: Exception):
     assert "ExceptionPropertiesProvider failed" in caplog.text
 
 
+def test_invalid_failure_details_properties_do_not_mask_original(caplog: LogCaptureFixture):
+    class InvalidProvider:
+        def get_exception_properties(self, exception: Exception):
+            return ["invalid"]
+
+    details = helpers.new_failure_details(
+        ValueError("original"), InvalidProvider(), TEST_LOGGER)
+
+    assert details.errorMessage == "original"
+    assert not details.properties
+    assert "ExceptionPropertiesProvider returned invalid properties" in caplog.text
+
+
 def test_task_failure_and_orchestration_state_expose_properties():
     proto = helpers.new_failure_details(ValueError("boom"), _PropertiesProvider())