2021-04-10 15:22:35 +00:00
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from construct import *
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2021-04-10 17:05:37 +00:00
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from pySim.utils import b2h, h2b, swap_nibbles
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2021-04-10 15:22:35 +00:00
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"""Utility code related to the integration of the 'construct' declarative parser."""
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# (C) 2021 by Harald Welte <laforge@osmocom.org>
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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class HexAdapter(Adapter):
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"""convert a bytes() type to a string of hex nibbles."""
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def _decode(self, obj, context, path):
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return b2h(obj)
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def _encode(self, obj, context, path):
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return h2b(obj)
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2021-04-10 17:05:37 +00:00
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class BcdAdapter(Adapter):
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"""convert a bytes() type to a string of BCD nibbles."""
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def _decode(self, obj, context, path):
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return swap_nibbles(b2h(obj))
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def _encode(self, obj, context, path):
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return h2b(swap_nibbles(obj))
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2021-04-10 15:22:35 +00:00
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def filter_dict(d, exclude_prefix='_'):
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"""filter the input dict to ensure no keys starting with 'exclude_prefix' remain."""
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res = {}
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for (key, value) in d.items():
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if key.startswith(exclude_prefix):
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continue
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if type(value) is dict:
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res[key] = filter_dict(value)
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else:
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res[key] = value
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return res
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# here we collect some shared / common definitions of data types
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LV = Prefixed(Int8ub, HexAdapter(GreedyBytes))
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2021-04-12 09:43:22 +00:00
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# Default value for Reserved for Future Use (RFU) bits/bytes
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# See TS 31.101 Sec. "3.4 Coding Conventions"
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__RFU_VALUE = 0
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# Field that packs Reserved for Future Use (RFU) bit
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FlagRFU = Default(Flag, __RFU_VALUE)
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# Field that packs Reserved for Future Use (RFU) byte
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ByteRFU = Default(Byte, __RFU_VALUE)
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# Field that packs all remaining Reserved for Future Use (RFU) bytes
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GreedyBytesRFU = Default(GreedyBytes, b'')
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def BitsRFU(n=1):
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'''
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Field that packs Reserved for Future Use (RFU) bit(s)
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as defined in TS 31.101 Sec. "3.4 Coding Conventions"
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Use this for (currently) unused/reserved bits whose contents
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should be initialized automatically but should not be cleared
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in the future or when restoring read data (unlike padding).
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Parameters:
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n (Integer): Number of bits (default: 1)
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'''
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return Default(BitsInteger(n), __RFU_VALUE)
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def BytesRFU(n=1):
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'''
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Field that packs Reserved for Future Use (RFU) byte(s)
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as defined in TS 31.101 Sec. "3.4 Coding Conventions"
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Use this for (currently) unused/reserved bytes whose contents
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should be initialized automatically but should not be cleared
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in the future or when restoring read data (unlike padding).
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Parameters:
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n (Integer): Number of bytes (default: 1)
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'''
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return Default(Bytes(n), __RFU_VALUE)
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