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Missing multi-part (TP DT) messages can cause data corruption (#72). #73

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Missing multi-part (TP DT) messages can cause data corruption (#72). #73

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12 changes: 12 additions & 0 deletions j1939/j1939_21.py
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Original file line number Diff line number Diff line change
Expand Up @@ -305,6 +305,7 @@ def _process_tp_cm(self, mid, dest_address, data, timestamp):
'deadline': time.time() + self.Timeout.T2,
'src_address' : src_address,
'dest_address' : dest_address,
'next_seq_num' : 1,
}

self.__send_tp_cts(dest_address, src_address, self._rcv_buffer[buffer_hash]['num_packages_max_rec'], 1, pgn)
Expand Down Expand Up @@ -367,6 +368,7 @@ def _process_tp_cm(self, mid, dest_address, data, timestamp):
"deadline": time.time() + self.Timeout.T1,
'src_address' : src_address,
'dest_address' : dest_address,
'next_seq_num' : 1,
}
self.__job_thread_wakeup()
elif control_byte == self.ConnectionMode.ABORT:
Expand All @@ -390,9 +392,19 @@ def _process_tp_dt(self, mid, dest_address, data, timestamp):
# TODO: LOG/TRACE/EXCEPTION?
return

if self._rcv_buffer[buffer_hash]['next_seq_num'] != sequence_number:
logger.critical(f"packet error. out-of-sequence pgn: {self._rcv_buffer[buffer_hash]['pgn']} "
f"required: {self._rcv_buffer[buffer_hash]['next_seq_num']} "
f"received: {sequence_number}")
del self._rcv_buffer[buffer_hash]
self.__job_thread_wakeup()
return

# get data
self._rcv_buffer[buffer_hash]['data'].extend(data[1:])

self._rcv_buffer[buffer_hash]['next_seq_num'] = sequence_number + 1

# message is complete with sending an acknowledge
if len(self._rcv_buffer[buffer_hash]['data']) >= self._rcv_buffer[buffer_hash]['message_size']:
logger.info("finished RCV of PGN {} with size {}".format(self._rcv_buffer[buffer_hash]['pgn'], self._rcv_buffer[buffer_hash]['message_size']))
Expand Down