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pySim.commands: Move away from pytlv for FCP parsing

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This is the last pytlv use in non-legacy code, let's replace our
open-coded raw FCP parsing with the proper FCP parser we have in
ts_102_2221.py.

Change-Id: Ic5c5eec3b654b25e70c23c020910353cc5919aa9
This commit is contained in:
Harald Welte
2024-09-19 07:48:13 +02:00
parent a01e87da77
commit a9bb63a2db
1 changed files with 5 additions and 40 deletions
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45
pySim/commands.py
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@@ -32,6 +32,7 @@ from osmocom.tlv import bertlv_encode_len
from pySim.utils import sw_match, expand_hex, SwHexstr, ResTuple, SwMatchstr
from pySim.exceptions import SwMatchError
from pySim.transport import LinkBase
from pySim.ts_102_221 import decode_select_response
# A path can be either just a FID or a list of FID
Path = typing.Union[Hexstr, List[Hexstr]]
@@ -176,40 +177,6 @@ class SimCardCommands:
raise SwMatchError(sw, sw_exp.lower(), self._tp.sw_interpreter)
return (rsp, sw)
# Extract a single FCP item from TLV
def __parse_fcp(self, fcp: Hexstr):
# see also: ETSI TS 102 221, chapter 11.1.1.3.1 Response for MF,
# DF or ADF
from pytlv.TLV import TLV
tlvparser = TLV(['82', '83', '84', 'a5', '8a', '8b',
'8c', '80', 'ab', 'c6', '81', '88'])
# pytlv is case sensitive!
fcp = fcp.lower()
if fcp[0:2] != '62':
raise ValueError(
'Tag of the FCP template does not match, expected 62 but got %s' % fcp[0:2])
# Unfortunately the spec is not very clear if the FCP length is
# coded as one or two byte vale, so we have to try it out by
# checking if the length of the remaining TLV string matches
# what we get in the length field.
# See also ETSI TS 102 221, chapter 11.1.1.3.0 Base coding.
# TODO: this likely just is normal BER-TLV ("All data objects are BER-TLV except if otherwise # defined.")
exp_tlv_len = int(fcp[2:4], 16)
if len(fcp[4:]) // 2 == exp_tlv_len:
skip = 4
else:
exp_tlv_len = int(fcp[2:6], 16)
if len(fcp[4:]) // 2 == exp_tlv_len:
skip = 6
raise ValueError('Cannot determine length of TLV-length')
# Skip FCP tag and length
tlv = fcp[skip:]
return tlvparser.parse(tlv)
# Tell the length of a record by the card response
# USIMs respond with an FCP template, which is different
# from what SIMs responds. See also:
@@ -217,10 +184,8 @@ class SimCardCommands:
# SIM: GSM 11.11, chapter 9.2.1 SELECT
def __record_len(self, r) -> int:
if self.sel_ctrl == "0004":
tlv_parsed = self.__parse_fcp(r[-1])
file_descriptor = tlv_parsed['82']
# See also ETSI TS 102 221, chapter 11.1.1.4.3 File Descriptor
return int(file_descriptor[4:8], 16)
fcp_parsed = decode_select_response(r[-1])
return fcp_parsed['file_descriptor']['record_len']
else:
return int(r[-1][28:30], 16)
@@ -228,8 +193,8 @@ class SimCardCommands:
# above.
def __len(self, r) -> int:
if self.sel_ctrl == "0004":
tlv_parsed = self.__parse_fcp(r[-1])
return int(tlv_parsed['80'], 16)
fcp_parsed = decode_select_response(r[-1])
return fcp_parsed['file_size']
else:
return int(r[-1][4:8], 16)