Do not report error in listen mode when listening to the transmitter (#127)

Author: pylessard

isotp/protocol.py

@@ -709,12 +709,15 @@ def send(self,
         :type send_timeout: float or None
 
         :raises ValueError: Given data is not a bytearray, a tuple (generator,size) or the size is too big
-        :raises RuntimeError: Transmit queue is full
+        :raises RuntimeError: Transmit queue is full or tried to transmit while the stack is configured in :ref:`listen mode<param_listen_mode>`
         :raises BlockingSendTimeout: When :ref:`blocking_send<param_blocking_send>` is set to ``True`` and the send operation does not complete in the given timeout.
         :raises BlockingSendFailure: When :ref:`blocking_send<param_blocking_send>` is set to ``True`` and the transmission failed for any reason (e.g. unexpected frame or bad timings), including a timeout. Note that 
             :class:`BlockingSendTimeout<BlockingSendTimeout>` inherits :class:`BlockingSendFailure<BlockingSendFailure>`.
         """
 
+        if self.params.listen_mode:
+            raise RuntimeError("Cannot transmit when listen_mode=True")
+
         if target_address_type is None:
             target_address_type = self.params.default_target_address_type
         else:
@@ -1007,13 +1010,13 @@ def _process_tx(self) -> ProcessTxReport:
                 return self.ProcessTxReport(msg=None, immediate_rx_required=False)
 
             if self.tx_state == self.TxState.IDLE:
-                self._trigger_error(isotp.errors.UnexpectedFlowControlError('Received a FlowControl message while transmission was Idle. Ignoring'))
+                self._trigger_error(isotp.errors.UnexpectedFlowControlError('Received a FlowControl message while transmission was Idle. Ignoring'), inhibit_in_listen_mode=True)
             else:
                 if flow_control_frame.flow_status == PDU.FlowStatus.Wait:
-                    if self.params.wftmax == 0:
+                    if self.params.wftmax == 0 and not self.params.listen_mode:
                         self._trigger_error(isotp.errors.UnsupportedWaitFrameError(
                             'Received a FlowControl requesting to wait, but wftmax is set to 0'))
-                    elif self.wft_counter >= self.params.wftmax:
+                    elif self.wft_counter >= self.params.wftmax and not self.params.listen_mode:
                         self._trigger_error(isotp.errors.MaximumWaitFrameReachedError(
                             'Received %d wait frame which is the maximum set in params.wftmax' % (self.wft_counter)))
                         self._stop_sending(success=False)
@@ -1388,10 +1391,11 @@ def _start_reception_after_first_frame_if_valid(self, pdu: PDU) -> bool:
 
         return started
 
-    def _trigger_error(self, error: isotp.errors.IsoTpError) -> None:
+    def _trigger_error(self, error: isotp.errors.IsoTpError, inhibit_in_listen_mode:bool=False) -> None:
         if self.error_handler is not None:
             if hasattr(self.error_handler, '__call__') and isinstance(error, isotp.errors.IsoTpError):
-                self.error_handler(error)
+                if not (inhibit_in_listen_mode and self.params.listen_mode):
+                    self.error_handler(error)
             else:
                 self.logger.warning('Given error handler is not a callable object.')
 

test/test_transport_layer.py

@@ -104,7 +104,7 @@ def error_handler(self, error):
         self.error_triggered[error.__class__].append(error)
 
     def assert_no_error_reported(self):
-        self.assertEqual(len(self.error_triggered), 0, "At least 1 error was reported")
+        self.assertEqual(len(self.error_triggered), 0, "Errors were reported and shouldn't have")
 
     def read_queue_blocking(self, q: queue.Queue, timeout: float):
         try:
@@ -171,7 +171,11 @@ def test_blocking_send(self):
         self.layer1.send(bytes([1] * 100), send_timeout=5)
         self.assert_no_error_reported()
 
-    def test_listen_mode(self):
+    def test_listen_mode_receiver(self):
+        # listen mode enabled. Address is the receiver address
+        self.layer2.params.blocksize=5
+        self.layer2.params.stmin=10
+        self.layer2.load_params()
         layer3_rx_queue = queue.Queue()
         layer3_tx_queue = queue.Queue()
 
@@ -206,6 +210,64 @@ def test_listen_mode(self):
         finally:
             layer3.stop()
 
+    def test_listen_mode_transmitter(self):
+        # listen mode enabled. Address is the transmitter address
+        # Expect no errors
+        self.layer2.params.blocksize=5
+        self.layer2.params.stmin=10
+        self.layer2.load_params()
+        layer3_rx_queue = queue.Queue()
+        layer3_tx_queue = queue.Queue()
+
+        self.queue1to2.add_tx_splice(layer3_rx_queue)
+        self.queue2to1.add_tx_splice(layer3_rx_queue)
+
+        params3 = self.STACK_PARAMS.copy()
+        params3.update(dict(logger_name='layer3', listen_mode=True))
+
+        # Layer 3 should receive the same thing as layer 2 even though it receives all messages
+        layer3 = isotp.TransportLayer(
+            txfn=partial(self.send_queue, layer3_tx_queue),
+            rxfn=partial(self.read_queue_blocking, layer3_rx_queue),
+            address=self.address1,
+            error_handler=self.error_handler,
+            params=params3
+        )
+
+        unittest_logging.configure_transport_layer(layer3)
+        layer3.start()
+        try:
+            payload = bytes([x % 255 for x in range(100)])
+            self.layer1.send(payload)
+            payload2 = self.layer2.recv(block=True, timeout=5)
+            self.assertEqual(payload, payload2)
+
+            self.assertFalse(layer3.available())    # Address does not match receiver address
+            
+            self.assert_no_error_reported()
+            self.assertTrue(layer3_tx_queue.empty())    # layer3 cannot send
+        finally:
+            layer3.stop()
+
+    def test_listen_mode_cannot_transmit(self):
+        params3 = self.STACK_PARAMS.copy()
+        params3.update(dict(logger_name='layer3', listen_mode=True))
+
+        layer3_tx_queue = queue.Queue()
+        layer3_rx_queue = queue.Queue()
+        # Layer 3 should receive the same thing as layer 2 even though it receives all messages
+        layer3 = isotp.TransportLayer(
+            txfn=partial(self.send_queue, layer3_tx_queue),
+            rxfn=partial(self.read_queue_blocking, layer3_rx_queue),
+            address=self.address1,
+            error_handler=self.error_handler,
+            params=params3
+        )
+
+        with self.assertRaises(Exception):
+            layer3.send(bytes([1,2,3,4,5]))
+
+
     def test_no_call_to_process_after_start(self):
         # Make sure we maintain backward compatibility without introducing weird race conditions into old application
         with self.assertRaises(RuntimeError):
@@ -287,7 +349,7 @@ def error_handler(self, error):
         self.error_triggered[error.__class__].append(error)
 
     def assert_no_error_reported(self):
-        self.assertEqual(len(self.error_triggered), 0, "At least 1 error was reported")
+        self.assertEqual(len(self.error_triggered), 0, "Errors were reported and shouldn't have")
 
     def read_queue_blocking(self, q: queue.Queue, timeout: float):
         try: