Improve errors for SetScratchpadTargetAndActionRequest.from_payload()

If constructing a new SetScratchpadTargetAndActionRequest from payload
fails due to invalid values, a new InvalidMessageContents exception is
raised. This exception can hold the header of the request message, and
it would be possible to generate a response with the corresponding
req_id based on the exception.

tests/test_set_scratchpad_target.py

@@ -1,9 +1,14 @@
 # flake8: noqa
 
-import wirepas_mesh_messaging
 import enum
+
+import pytest
 from default_value import *
 
+import wirepas_mesh_messaging
+from wirepas_mesh_messaging.proto.generic_message_pb2 import GenericMessage
+from wirepas_mesh_messaging.wirepas_exceptions import InvalidMessageContents
+
 
 def test_generate_parse_request_with_raw():
     request = wirepas_mesh_messaging.SetScratchpadTargetAndActionRequest(
@@ -62,3 +67,78 @@ def test_generate_parse_response():
             assert v.value == request2.__dict__[k].value
         else:
             assert v == request2.__dict__[k]
+
+
+def test_constructing_request_with_too_large_target_sequence_should_fail():
+    target_and_action = {
+        "action": wirepas_mesh_messaging.ScratchpadAction.ACTION_PROPAGATE_ONLY,
+        "target_sequence": 0x100,
+    }
+    with pytest.raises(ValueError):
+        wirepas_mesh_messaging.SetScratchpadTargetAndActionRequest(
+            SINK_ID, target_and_action, REQUEST_ID
+        )
+
+
+def test_constructing_request_with_too_large_target_crc_should_fail():
+    target_and_action = {
+        "action": wirepas_mesh_messaging.ScratchpadAction.ACTION_PROPAGATE_ONLY,
+        "target_crc": 0x10000,
+    }
+    with pytest.raises(ValueError):
+        wirepas_mesh_messaging.SetScratchpadTargetAndActionRequest(
+            SINK_ID, target_and_action, REQUEST_ID
+        )
+
+
+def test_constructing_request_with_too_large_raw_action_should_fail():
+    target_and_action = {
+        "action": wirepas_mesh_messaging.ScratchpadAction.ACTION_PROPAGATE_AND_PROCESS,
+        "param": 0x100,
+    }
+    with pytest.raises(ValueError):
+        wirepas_mesh_messaging.SetScratchpadTargetAndActionRequest(
+            SINK_ID, target_and_action, REQUEST_ID
+        )
+
+
+def test_decoding_request_with_too_large_target_sequence_should_fail_with_correct_exception():
+    TEST_TIME = 34567
+    base_request = wirepas_mesh_messaging.SetScratchpadTargetAndActionRequest(
+        SINK_ID, SCRATCHPAD_TARGET_RAW, REQUEST_ID, time_ms_epoch=TEST_TIME
+    )
+    message = GenericMessage()
+    message.ParseFromString(base_request.payload)
+    message.wirepas.set_scratchpad_target_and_action_req.target_and_action.target_sequence = (
+        0x100
+    )
+    test_payload = message.SerializeToString()
+
+    with pytest.raises(InvalidMessageContents) as exc_info:
+        wirepas_mesh_messaging.SetScratchpadTargetAndActionRequest.from_payload(
+            test_payload
+        )
+    assert exc_info.value.header["req_id"] == REQUEST_ID
+    assert exc_info.value.header["sink_id"] == SINK_ID
+    assert exc_info.value.header["time_ms_epoch"] == TEST_TIME
+
+
+def test_decoding_request_with_too_large_target_crc_should_fail_with_correct_exception():
+    TEST_TIME = 1234567
+    base_request = wirepas_mesh_messaging.SetScratchpadTargetAndActionRequest(
+        SINK_ID_2, SCRATCHPAD_TARGET_RAW, REQUEST_ID, time_ms_epoch=TEST_TIME
+    )
+    message = GenericMessage()
+    message.ParseFromString(base_request.payload)
+    message.wirepas.set_scratchpad_target_and_action_req.target_and_action.target_crc = (
+        0x10000
+    )
+    test_payload = message.SerializeToString()
+
+    with pytest.raises(InvalidMessageContents) as exc_info:
+        wirepas_mesh_messaging.SetScratchpadTargetAndActionRequest.from_payload(
+            test_payload
+        )
+    assert exc_info.value.header["req_id"] == REQUEST_ID
+    assert exc_info.value.header["sink_id"] == SINK_ID_2
+    assert exc_info.value.header["time_ms_epoch"] == TEST_TIME

wirepas_mesh_messaging/set_scratchpad_target.py

@@ -7,6 +7,7 @@
         See file LICENSE for full license details.
 """
 
+from wirepas_mesh_messaging.wirepas_exceptions import InvalidMessageContents
 from .proto import GenericMessage
 
 from .request import Request
@@ -86,15 +87,22 @@ def _get_related_message(generic_message):
     def from_payload(cls, payload):
         req = cls._decode_and_get_related_message(payload)
 
-        d = Request._parse_request_header(req.header)
+        header = Request._parse_request_header(req.header)
 
         target = {}
         parse_scratchpad_target(req.target_and_action, target)
 
-        return cls(sink_id=d["sink_id"],
-                   target=target,
-                   req_id=d["req_id"],
-                   time_ms_epoch=d["time_ms_epoch"])
+        try:
+            return cls(
+                sink_id=header["sink_id"],
+                target=target,
+                req_id=header["req_id"],
+                time_ms_epoch=header["time_ms_epoch"],
+            )
+        except ValueError as e:
+            raise InvalidMessageContents(
+                f"Invalid values in {cls.__name__}", header
+            ) from e
 
     @property
     def payload(self):

wirepas_mesh_messaging/wirepas_exceptions.py

@@ -17,3 +17,16 @@ class InvalidMessageType(GatewayAPIParsingException):
     """
     Exception indicating wrong message type during deserialization
     """
+
+class InvalidMessageContents(GatewayAPIParsingException):
+    """
+    Exception indicating invalid message contents in the received message.
+
+    Parameters:
+        - message: The exception message
+        - header: Parsed header of the message, as a dictionary
+    """
+
+    def __init__(self, message, header):
+        super().__init__(message)
+        self.header = header