Ignore signal values that are out of the defined range

The message definition database may contain signals for which a
minimum and/or maximum value has been defined. In particular,
j1939 uses "special" out-of-range values to indicate that a signal
is not available (at the moment). These "special" values should not
be published to the Databroker.

The CanReader has been altered to ignore signal values from CAN
messages which do not match the defined min/max values.

dbc2val/dbcfeederlib/canreader.py

@@ -18,6 +18,8 @@
 
 from abc import ABC, abstractmethod
 
+import cantools.database  # type: ignore
+
 from dbcfeederlib.canplayer import CANplayer
 from dbcfeederlib.dbc2vssmapper import Mapper, VSSObservation
 from typing import Any, Dict, Optional
@@ -89,7 +91,25 @@ def _process_can_message(self, frame_id: int, data: Any):
                     log.debug("Decoded message: %s", str(decode))
                 rx_time = time.time()
                 for signal_name, raw_value in decode.items():  # type: ignore
+                    signal: cantools.database.Signal = message_def.get_signal_by_name(signal_name)
+                    if isinstance(raw_value, (int, float)):
+                        # filter out signals with values out of defined range
+                        # which is usually because the signal's value is unavailable
+                        # (represented as e.g. "all bits set")
+                        if signal.minimum is not None and raw_value < signal.minimum:
+                            log.debug(
+                                "discarding out-of-range value [signal: %s, min: %s, value: %s]",
+                                signal_name, signal.minimum, raw_value
+                            )
+                            continue
+                        if signal.maximum is not None and raw_value > signal.maximum:
+                            log.debug(
+                                "discarding out-of-range value [signal: %s, max: %s, value: %s]",
+                                signal_name, signal.maximum, raw_value
+                            )
+                            continue
                     for signal_mapping in self._mapper.get_dbc2vss_mappings(signal_name):
+
                         if signal_mapping.time_condition_fulfilled(rx_time):
                             log.debug(
                                 "Queueing %s, triggered by %s, raw value %s",