From b0c9ccba66ebe861a7ff8b18e2f778a0d365670b Mon Sep 17 00:00:00 2001 From: Harald Welte Date: Thu, 4 Jan 2024 21:18:31 +0100 Subject: [PATCH] construct: avoid StreamError exceptions due to files containing all-ff In smart cards, files/records containing all-ff means they are simply not used/initialized. Let's avoid raising exceptions when interpreting 0xff as length value and reading less bytes as value. Change-Id: I09c3cb82063fc094eb047749996a6eceff757ea2 --- pySim/construct.py | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/pySim/construct.py b/pySim/construct.py index 1ed3576d..0c82c413 100644 --- a/pySim/construct.py +++ b/pySim/construct.py @@ -402,7 +402,16 @@ def parse_construct(c, raw_bin_data: bytes, length: typing.Optional[int] = None, """Helper function to wrap around normalize_construct() and filter_dict().""" if not length: length = len(raw_bin_data) - parsed = c.parse(raw_bin_data, total_len=length, **context) + try: + parsed = c.parse(raw_bin_data, total_len=length, **context) + except StreamError as e: + # if the input is all-ff, this means the content is undefined. Let's avoid passing StreamError + # exceptions in those situations (which might occur if a length field 0xff is 255 but then there's + # actually less bytes in the remainder of the file. + if all([v == 0xff for v in raw_bin_data]): + return None + else: + raise e return normalize_construct(parsed) def build_construct(c, decoded_data, context: dict = {}):