Fix XNCP parsing for hacked LIDL gateway (#657)

Author: puddly

bellows/ezsp/xncp.py

@@ -67,6 +67,12 @@ def from_payload(cls, payload: XncpCommandPayload) -> XncpCommand:
     def from_bytes(cls, data: bytes) -> XncpCommand:
         command_id, data = XncpCommandId.deserialize(data)
         status, data = EmberStatus.deserialize(data)
+
+        if command_id not in COMMANDS:
+            raise ValueError(
+                f"Unknown XNCP command ID: 0x{command_id:04X} (payload {data!r})"
+            )
+
         payload, rest = COMMANDS[command_id].deserialize(data)
 
         if rest:

tests/test_xncp.py

@@ -48,6 +48,20 @@ async def test_xncp_failure_multiprotocol(ezsp_f: EZSP) -> None:
     ]
 
 
+async def test_xncp_failure_lidl(ezsp_f: EZSP) -> None:
+    """Test XNCP failure with hacked LIDL gateway."""
+    ezsp_f._mock_commands["customFrame"] = customFrame = AsyncMock(
+        return_value=[t.EmberStatus.SUCCESS, b"\x00\x01\x03"]
+    )
+
+    with pytest.raises(InvalidCommandError):
+        await ezsp_f.xncp_get_supported_firmware_features()
+
+    assert customFrame.mock_calls == [
+        call(xncp.XncpCommand.from_payload(xncp.GetSupportedFeaturesReq()).serialize())
+    ]
+
+
 async def test_xncp_failure_unknown(ezsp_f: EZSP) -> None:
     """Test XNCP failure, unknown command."""
     ezsp_f._mock_commands["customFrame"] = customFrame = AsyncMock(