def _validate_and_strip_checksum(line):
"""Verify the simple 16-bit checksum and remove it from the line.
Args:
line: the line to check the checksum of.
Returns:
A copy of the line with the checksum stripped out.
"""
match = _RESPONSE_MATCH.match(line)
if not match:
raise lifescan.MissingChecksum(line)
response, checksum_string = match.groups()
try:
checksum_given = int(checksum_string, 16)
checksum_calculated = _calculate_checksum(bytes(response, 'ascii'))
if checksum_given != checksum_calculated:
raise exceptions.InvalidChecksum(checksum_given,
checksum_calculated)
except ValueError:
raise exceptions.InvalidChecksum(checksum_given, None)
return response
def _read_text_response(self) -> Sequence[bytes]:
all_lines: List[bytes] = []
while True:
line = self._readline()
if not line.endswith(b"\r\n"):
raise exceptions.InvalidResponse(
f"Corrupted response line: {line!r}")
all_lines.append(line)
if line == b"]\r\n":
break
if all_lines[0] != b"[\r\n":
raise exceptions.InvalidResponse(
f"Unexpected first response line: {all_lines!r}")
wire_checksum = int(all_lines[-2][:-2], base=16)
calculated_checksum = _crc8_maxim(b"".join(all_lines[:-2]))
if wire_checksum != calculated_checksum:
raise exceptions.InvalidChecksum(wire_checksum,
calculated_checksum)
return [line[:-2] for line in all_lines[1:-2]]
def _fetch_device_information(self):
data = self._send_command('mem')
res = _parse_result(data)
self.info_ = res['info']
self.device_results_ = res['reslog']
self.device_checksum_ = res['checksum']
self.device_version_ = self.info_['device_version_']
self.software_revision_ = self.info_['software_revision_']
self.device_serialno_ = self.info_['device_serialno_']
self.device_glucose_unit_ = self.info_['device_glucose_unit_']
self.device_current_date_time_ = self.info_[
'device_current_date_time_']
self.device_nrresults_ = self.info_['device_nrresults_']
# exclude the last line which is the checksum itself.
# every line is ended with a windows end-of-line \r\n
# except line 6 ends with a linux end-of-line \n
n = self.device_nrresults_
if n > 0:
wnl = (ord('\r') + ord('\n')) * (_INFO_SIZE + n
) # windows end of line
lnl = ord('\n') # linux end of line
ce = self.device_checksum_ # expected
cg = (sum(ord(c) for c in ''.join(data[:-1])) + wnl + lnl) % (
2**16) # gotten
if ce != cg:
raise exceptions.InvalidChecksum(ce, cg)
def _verify_checksum(message, expected_checksum_hex):
"""Calculate the simple checksum of the message and compare with expected.
Args:
message: (str) message to calculate the checksum of.
expected_checksum_hex: (str) hexadecimal string representing the checksum
expected to match the message.
Raises:
InvalidChecksum: if the message checksum calculated does not match the one
received.
"""
expected_checksum = int(expected_checksum_hex, 16)
calculated_checksum = sum(ord(c) for c in message)
if expected_checksum != calculated_checksum:
raise exceptions.InvalidChecksum(expected_checksum, calculated_checksum)
def _extract_message(register):
"""Parse the message preamble and verify checksums."""
stx, length = _STRUCT_PREAMBLE.unpack_from(register)
if stx != _STX:
raise lifescan.MalformedCommand('invalid STX byte: %02x' % stx)
if length > _REGISTER_SIZE:
raise lifescan.MalformedCommand('invalid length: %d > REGISTER_SIZE' %
length)
# 2 is the length of the checksum, so it should be ignored.
calculated_checksum = lifescan.crc_ccitt(register[:(length - 2)])
coda_offset = length - _STRUCT_CODA.size
etx, encoded_checksum = _STRUCT_CODA.unpack_from(register[coda_offset:])
if etx != _ETX:
raise lifescan.MalformedCommand('invalid ETX byte: %02x' % etx)
if encoded_checksum != calculated_checksum:
raise exceptions.InvalidChecksum(encoded_checksum, calculated_checksum)
response = register[_STRUCT_PREAMBLE.size:coda_offset]
return response
def _verify_checksum(message: AnyStr, expected_checksum_hex: AnyStr) -> None:
"""Calculate the simple checksum of the message and compare with expected.
Args:
message: (str) message to calculate the checksum of.
expected_checksum_hex: hexadecimal string representing the checksum
expected to match the message.
Raises:
InvalidChecksum: if the message checksum calculated does not match the one
received.
"""
expected_checksum = int(expected_checksum_hex, 16)
if isinstance(message, bytes):
all_bytes = (c for c in message)
else:
all_bytes = (ord(c) for c in message)
calculated_checksum = sum(all_bytes)
if expected_checksum != calculated_checksum:
raise exceptions.InvalidChecksum(expected_checksum, calculated_checksum)
def get_readings(self) -> Generator[common.AnyReading, None, None]:
"""Iterates over the reading values stored in the glucometer.
Args:
unit: The glucose unit to use for the output.
Yields: A tuple (date, value) of the readings in the glucometer. The
value is a floating point in the unit specified; if no unit is
specified, the default unit in the glucometer will be used.
Raises:
exceptions.InvalidResponse: if the response does not match what '
expected.
"""
data = self._send_command("xmem")
# The first line is empty, the second is the serial number, the third
# the version, the fourth the current time, and the fifth the record
# count.. The last line has a checksum and the end.
count = int(data[4])
if count != (len(data) - 6):
raise exceptions.InvalidResponse("\n".join(data))
# Extract the checksum from the last line.
checksum_match = _CHECKSUM_RE.match(data[-1])
if not checksum_match:
raise exceptions.InvalidResponse("\n".join(data))
expected_checksum = int(checksum_match.group("checksum"), 16)
# exclude the last line in the checksum calculation, as that's the
# checksum itself. The final \r\n is added separately.
calculated_checksum = sum(ord(c) for c in "\r\n".join(data[:-1])) + 0xD + 0xA
if expected_checksum != calculated_checksum:
raise exceptions.InvalidChecksum(expected_checksum, calculated_checksum)
for line in data[5:-1]:
match = _READING_RE.match(line)
if not match:
raise exceptions.InvalidResponse(line)
if match.group("type") != "G":
logging.warning("Non-glucose readings are not supported, ignoring.")
continue
if match.group("reading") == "HI ":
value = float("inf")
else:
value = float(match.group("reading"))
day = int(match.group("day"))
month = _MONTH_MATCHES[match.group("month")]
year = int(match.group("year"))
hour, minute = map(int, match.group("time").split(":"))
timestamp = datetime.datetime(year, month, day, hour, minute)
# The reading, if present, is always in mg/dL even if the glucometer
# is set to mmol/L.
yield common.GlucoseReading(timestamp, value)
def validate_checksum(self):
expected_checksum = self.checksum
received_checksum = self._STRUCT.unpack(self.cmd[_IDX_CHECKSUM:])[0]
if received_checksum != expected_checksum:
raise exceptions.InvalidChecksum(expected_checksum,
received_checksum)
def get_readings(self):
"""Iterates over the reading values stored in the glucometer.
Args:
unit: The glucose unit to use for the output.
Yields:
A tuple (date, value) of the readings in the glucometer. The value is a
floating point in the unit specified; if no unit is specified, the default
unit in the glucometer will be used.
Raises:
exceptions.InvalidResponse: if the response does not match what expected.
"""
data = self._send_command('xmem')
# The first line is empty, the second is the serial number, the third the
# version, the fourth the current time, and the fifth the record count.. The
# last line has a checksum and the end.
count = int(data[4])
if count != (len(data) - 6):
raise exceptions.InvalidResponse('\n'.join(data))
# Extract the checksum from the last line.
checksum_match = _CHECKSUM_RE.match(data[-1])
if not checksum_match:
raise exceptions.InvalidResponse('\n'.join(data))
expected_checksum = int(checksum_match.group('checksum'), 16)
# exclude the last line in the checksum calculation, as that's the checksum
# itself. The final \r\n is added separately.
calculated_checksum = sum(ord(c)
for c in '\r\n'.join(data[:-1])) + 0xd + 0xa
if expected_checksum != calculated_checksum:
raise exceptions.InvalidChecksum(expected_checksum,
calculated_checksum)
for line in data[5:-1]:
match = _READING_RE.match(line)
if not match:
raise exceptions.InvalidResponse(line)
if match.group('type') != 'G':
print('Non-glucose readings are not supported, ignoring.',
file=sys.stderr)
continue
if match.group('reading') == 'HI ':
value = float("inf")
else:
value = float(match.group('reading'))
day = int(match.group('day'))
month = _MONTH_MATCHES[match.group('month')]
year = int(match.group('year'))
hour, minute = map(int, match.group('time').split(':'))
timestamp = datetime.datetime(year, month, day, hour, minute)
# The reading, if present, is always in mg/dL even if the glucometer is
# set to mmol/L.
yield common.Reading(timestamp, value)
