def interpret_response(cls, response, tolerate_zero_padding=True):
"""
Populates the response ``service_data`` property with an instance of :class:`RequestFileTransfer.ResponseData<udsoncan.services.RequestFileTransfer.ResponseData>`
:param response: The received response to interpret
:type response: :ref:`Response<Response>`
:raises InvalidResponseException: If length of ``response.data`` is too short or payload does not respect ISO-14229 specifications
:raises NotImplementedError: If the MaxNumberOfBlock or fileSizeUncompressedOrDirInfoLength value is encoded over more than 8 bytes.
"""
from udsoncan import Filesize, DataFormatIdentifier
response.service_data = cls.ResponseData()
if len(response.data) < 1:
raise InvalidResponseException(
response, 'Response payload must be at least 1 byte long')
response.service_data.moop_echo = int(response.data[0])
has_lfid = response.service_data.moop_echo in [
cls.ModeOfOperation.AddFile, cls.ModeOfOperation.ReplaceFile,
cls.ModeOfOperation.ReadFile, cls.ModeOfOperation.ReadDir
]
has_dfi = response.service_data.moop_echo in [
cls.ModeOfOperation.AddFile, cls.ModeOfOperation.ReplaceFile,
cls.ModeOfOperation.ReadFile, cls.ModeOfOperation.ReadDir
]
has_filesize_length = response.service_data.moop_echo in [
cls.ModeOfOperation.ReadFile, cls.ModeOfOperation.ReadDir
]
has_uncompressed_filesize = response.service_data.moop_echo in [
cls.ModeOfOperation.ReadFile, cls.ModeOfOperation.ReadDir
]
has_compressed_filesize = response.service_data.moop_echo in [
cls.ModeOfOperation.ReadFile
]
cursor = 1
if has_lfid:
if len(response.data) < 2:
raise InvalidResponseException(
response,
'Response payload must be at least 2 byte long for Mode of operation %d'
% response.service_data.moop_echo)
lfid = int(response.data[1])
cursor = 2
if lfid > 8:
raise NotImplementedError(
'This client does not support number bigger than %d bits, but MaxNumberOfBlock is encoded on %d bits'
% ((8 * 8), (lfid * 8)))
if lfid == 0:
raise InvalidResponseException(
response,
'Received a MaxNumberOfBlockLength of 0 which is impossible'
)
if len(response.data) < 2 + lfid:
raise InvalidResponseException(
response,
'Response payload says that MaxNumberOfBlock is encoded on %d bytes, but only %d bytes are present'
% (lfid, (len(response.data) - 2)))
todecode = bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
for i in range(1, lfid + 1):
todecode[-i] = response.data[cursor + lfid - i]
response.service_data.max_length = struct.unpack('>q', todecode)[0]
cursor += lfid
if has_dfi:
if len(response.data) < cursor + 1:
raise InvalidResponseException(
response,
'Missing DataFormatIdentifier in received response')
response.service_data.dfi = DataFormatIdentifier.from_byte(
response.data[cursor])
cursor += 1
dfi = response.service_data.dfi.get_byte_as_int()
if response.service_data.moop_echo == cls.ModeOfOperation.ReadDir and dfi != 0:
raise InvalidResponseException(
response,
'DataFormatIdentifier for ReadDir can only be 0x00 as per ISO-14229, but its value was set to 0x%02x'
% (dfi))
if has_filesize_length:
if len(response.data) < cursor + 2:
raise InvalidResponseException(
response,
'Missing or incomplete FileSizeOrDirInfoParameterLength in received response'
)
fsodipl = struct.unpack('>H', response.data[cursor:cursor + 2])[0]
cursor += 2
if fsodipl > 8:
raise NotImplementedError(
response,
'This client does not support number bigger than %d bits, but FileSizeOrDirInfoLength is encoded on %d bits'
% ((8 * 8), (fsodipl * 8)))
if fsodipl == 0:
raise InvalidResponseException(
response,
'Received a FileSizeOrDirInfoParameterLength of 0 which is impossible'
)
if has_uncompressed_filesize:
if len(response.data) < cursor + fsodipl:
raise InvalidResponseException(
response,
'Missing or incomplete fileSizeUncompressedOrDirInfoLength in received response'
)
todecode = bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
for i in range(1, lfid + 1):
todecode[-i] = response.data[cursor + fsodipl - i]
uncompressed_size = struct.unpack('>q', todecode)[0]
cursor += fsodipl
else:
uncompressed_size = None
if has_compressed_filesize:
if len(response.data) < cursor + fsodipl:
raise InvalidResponseException(
response,
'Missing or incomplete fileSizeCompressed in received response'
)
todecode = bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
for i in range(1, lfid + 1):
todecode[-i] = response.data[cursor + fsodipl - i]
compressed_size = struct.unpack('>q', todecode)[0]
cursor += fsodipl
else:
compressed_size = None
if has_uncompressed_filesize and response.service_data.moop_echo == cls.ModeOfOperation.ReadDir:
response.service_data.dirinfo_length = uncompressed_size
else:
if has_uncompressed_filesize or has_compressed_filesize:
response.service_data.filesize = Filesize(
uncompressed=uncompressed_size, compressed=compressed_size)
if len(response.data) > cursor:
if response.data[cursor:] == b'\x00' * (
len(response.data) - cursor) and tolerate_zero_padding:
pass
else:
raise InvalidResponseException(
response,
'Response payload has extra data that has no meaning')
response.service_data = response.service_data
def test_from_byte(self):
dfi = DataFormatIdentifier.from_byte(0xAB)
self.assertEqual(dfi.compression, 0xA)
self.assertEqual(dfi.encryption, 0xB)