Improve NotifierBasedCanStack handling of error and remote frames (#143)

* Resolves #142 by inspecting incoming frames from the notifier and throwing away error frames and remote frames.

---------

Co-authored-by: tbeswick <[email protected]>

Author: TonyBeswick

isotp/protocol.py

@@ -1808,14 +1808,20 @@ def __init__(self, bus: "can.BusABC", notifier: "can.Notifier", *args: Any, **kw
 
     def start(self) -> None:
         self.buffered_reader = can.BufferedReader()
-        self.notifier.add_listener(self.buffered_reader)
+        self.notifier.add_listener(self._on_message_received)
         super().start()
 
     def stop(self) -> None:
         try:
             if self.buffered_reader is not None:
-                self.notifier.remove_listener(self.buffered_reader)
+                self.notifier.remove_listener(self._on_message_received)
         except Exception:
             pass
         self.buffered_reader = None
         super().stop()
+
+    def _on_message_received(self, msg: "can.Message") -> None:
+        if msg.is_error_frame or msg.is_remote_frame:
+            return
+        if self.buffered_reader is not None:
+            self.buffered_reader.on_message_received(msg)

test/test_can_stack.py

@@ -131,6 +131,18 @@ def test_send_10000(self):
         self.assertEqual(data, payload)
         self.assert_no_error_reported()
 
+    def test_1000_error_frames(self):
+        error_frame = can.Message(arbitration_id=0x8, is_extended_id=False, is_error_frame=True,
+                                  data=[0x0, 0x19, 0x81, 0x0])
+        for i in range(1000):
+            self.bus.send(error_frame)
+
+        payload = bytearray([x & 0xFF for x in range(5)])
+        self.layer1.send(payload)
+        data = self.layer2.recv(block=True, timeout=3)
+        self.assertEqual(data, payload)
+        self.assert_no_error_reported()
+
 
 if __name__ == '__main__':
     unittest.main()