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author | Harald Welte <laforge@osmocom.org> | 2021-04-10 17:22:35 +0200 |
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committer | Harald Welte <laforge@osmocom.org> | 2021-04-11 12:20:29 +0200 |
commit | e0f9ef16060f91d1ff36dbbac77ae44c9bac4b7a (patch) | |
tree | 5a4c0f683f849d23e7936e47dd2507dd3e13b309 /pySim/construct.py | |
parent | d0505bdb5574257ce52404384864a596227f79bb (diff) |
integrate 'construct' python library
'construct' is a declarative symmetric encoder/decoder for user
specified binary formats. It should come in extremely handy in
tools like pySim.
We start the integration by adding transport methods for transceiving
APDUs with built-in encoding of the command data and decoding of the
response data.
Change-Id: Ibf457aa8b9480a8db5979defcfafd67674303f6c
Diffstat (limited to 'pySim/construct.py')
-rw-r--r-- | pySim/construct.py | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/pySim/construct.py b/pySim/construct.py new file mode 100644 index 0000000..03d284e --- /dev/null +++ b/pySim/construct.py @@ -0,0 +1,42 @@ +from construct import * +from pySim.utils import b2h, h2b + +"""Utility code related to the integration of the 'construct' declarative parser.""" + +# (C) 2021 by Harald Welte <laforge@osmocom.org> +# +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation, either version 2 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. + + +class HexAdapter(Adapter): + """convert a bytes() type to a string of hex nibbles.""" + def _decode(self, obj, context, path): + return b2h(obj) + def _encode(self, obj, context, path): + return h2b(obj) + +def filter_dict(d, exclude_prefix='_'): + """filter the input dict to ensure no keys starting with 'exclude_prefix' remain.""" + res = {} + for (key, value) in d.items(): + if key.startswith(exclude_prefix): + continue + if type(value) is dict: + res[key] = filter_dict(value) + else: + res[key] = value + return res + +# here we collect some shared / common definitions of data types +LV = Prefixed(Int8ub, HexAdapter(GreedyBytes)) |