isotp error handler not propagated to uds connection #233

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1. elupus commented on May 23, 2024

   

   elupus

   on May 23, 2024

   Last edited by elupus

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   In general i might be that the protocol._stop_receiving() or _stop_sending() call is not propagated to the listener. not all error_handler calls abort the reception.
2. elupus commented on May 23, 2024

   

   elupus

   on May 23, 2024

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   Did the following hack to work around it:

   class Connection(PythonIsoTpConnection):
       def transport_error(self, exception: Exception):
           self.fromIsoTPQueue.put(exception)
   
       def specific_wait_frame(self, timeout=2):
           if not self.opened:
               raise RuntimeError("Connection is not open")
   
           frame = None
           try:
               frame = self.fromIsoTPQueue.get(block=True, timeout=timeout)
           except queue.Empty as exception:
               raise TimeoutException("Did not receive frame IsoTP Transport layer in time (timeout=%s sec)" % timeout) from exception
   
           if isinstance(frame, Exception):
               raise frame
   
           if self.mtu is not None:
               if frame is not None and len(frame) > self.mtu:
                   self.logger.warning("Truncating received payload to a length of %d" % (self.mtu))
                   frame = frame[0:self.mtu]
   
           return bytes(frame)  # isotp.protocol.TransportLayer uses bytearray. udsoncan is strict on bytes format
   

   Then hook that transport error into the isotp.CanStack.

   
           connection: Connection
           def transport_error(exception: Exception):
               connection.transport_error(exception)
   
           transport = isotp.CanStack(
               self.bus,
               address=isotp_addr,
               params=isotp_params,
               error_handler=transport_error,
           )
           connection = Connection(transport)
   

   But it gets ugly due to when and how the transport_error is registered. Maybe the recv() function of isotp should be changed to propagate these exceptions? In my case it's usually been "FlowControlTimeoutError: Reception of FlowControl timed out. Stopping transmission" that causes issues.
3. pylessard commented on May 26, 2024

   

   pylessard

   on May 26, 2024

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   Thanks, I see what you mean. The error should be reported to the upper layer.
   I will check this, but maybe not short term.