gsm_r: EF_Predefined: Decode first record different from others

In their infinite wisdom, the authors of the EIRENE FFFIS for GSM-R SIM
cards invented yet a new way of encoding data in SIM card files: The
first record of a file may be encoded differently than further records
of files.

This patch implements the feature based on the newly-introduced way by
which we pass the record number to the encoder and decoder methods.

Change-Id: Ib526f6c3c2ac9a945b8242e2e54536628376efc0
Related: OS#5784
This commit is contained in:
Harald Welte 2023-01-24 15:54:26 +01:00
parent f6b37af721
commit 6bf2d5f216
1 changed files with 18 additions and 6 deletions

View File

@ -237,17 +237,29 @@ class EF_Switching(LinFixedEF):
class EF_Predefined(LinFixedEF):
"""Section 8.5"""
# header and other records have different structure. WTF !?!
construct_first = Struct('next_table_type'/NextTableType,
'id_of_next_table'/HexAdapter(Bytes(2)))
construct_others = Struct('predefined_value1'/HexAdapter(Bytes(2)),
'string_table_index1'/Int8ub)
def __init__(self, fid, name, desc):
super().__init__(fid=fid, sfid=None,
name=name, desc=desc, rec_len=(3, 3))
# header and other records have different structure. WTF !?!
self._construct = Struct('next_table_type'/NextTableType,
'id_of_next_table'/HexAdapter(Bytes(2)),
'predefined_value1'/HexAdapter(Bytes(2)),
'string_table_index1'/Int8ub)
# TODO: predefined value n, ...
def _decode_record_bin(self, raw_bin_data : bytes, record_nr : int) -> dict:
if record_nr == 1:
return parse_construct(self.construct_first, raw_bin_data)
else:
return parse_construct(self.construct_others, raw_bin_data)
def _encode_record_bin(self, abstract_data : dict, record_nr : int) -> bytearray:
r = None
if record_nr == 1:
r = self.construct_first.build(abstract_data)
else:
r = self.construct_others.build(abstract_data)
return filter_dict(r)
class EF_DialledVals(TransparentEF):
"""Section 8.6"""