laforge has uploaded this change for review. ( https://gerrit.osmocom.org/c/pysim/+/38014?usp=email )

Change subject: pySim.esim.saip: Implement optimized file content encoding ......................................................................

pySim.esim.saip: Implement optimized file content encoding

Make sure we make use of the fill pattern when encoding file contents: Only encode the differences to the fill pattern of the file, in order to reduce the profile download size.

Change-Id: I61e4a5e04beba5c9092979fc546292d5ef3d7aad --- M pySim/esim/saip/__init__.py M tests/unittests/test_esim_saip.py 2 files changed, 81 insertions(+), 6 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/pysim refs/changes/14/38014/1

diff --git a/pySim/esim/saip/__init__.py b/pySim/esim/saip/__init__.py index 658810a..505ea30 100644 --- a/pySim/esim/saip/__init__.py +++ b/pySim/esim/saip/__init__.py @@ -20,6 +20,8 @@ import io from typing import Tuple, List, Optional, Dict, Union from collections import OrderedDict +from difflib import SequenceMatcher, Match + import asn1tools from osmocom.utils import b2h, h2b, Hexstr from osmocom.tlv import BER_TLV_IE, bertlv_parse_tag, bertlv_parse_len @@ -40,6 +42,29 @@

logger = logging.getLogger(__name__)

+class NonMatch(Match): + """Representing a contiguous non-matching block of data; the opposite of difflib.Match""" + @classmethod + def from_matchlist(cls, l: List[Match], size:int) -> List['NonMatch']: + """Build a list of non-matching blocks of data from its inverse (list of matching blocks). + The caller must ensure that the input list is ordered, non-overlapping and only contains + matches at equal offsets in a and b.""" + res = [] + cur = 0 + for match in l: + if match.a != match.b: + return ValueError('only works for equal-offset matches') + assert match.a >= cur + nm_len = match.a - cur + if nm_len > 0: + # there's no point in generating zero-lenth non-matching sections + res.append(cls(a=cur, b=cur, size=nm_len)) + cur = match.a + match.size + if size > cur: + res.append(cls(a=cur, b=cur, size=size-cur)) + + return res + class Naa: """A class defining a Network Access Application (NAA).""" name = None @@ -359,12 +384,33 @@ return ValueError("Unknown key '%s' in tuple list" % k) return stream.getvalue()

- def file_content_to_tuples(self) -> List[Tuple]: - # FIXME: simplistic approach. needs optimization. We should first check if the content - # matches the expanded default value from the template. If it does, return empty list. - # Next, we should compute the diff between the default value and self.body, and encode - # that as a sequence of fillFileOffset and fillFileContent tuples. - return [('fillFileContent', self.body)] + def file_content_to_tuples(self, optimize:bool = True) -> List[Tuple]: + if not optimize: + # simplistic approach: encode the full file, ignoring the template/default + return [('fillFileContent', self.body)] + # Try to 'compress' the file body, based on the default file contents. + if self.template: + default = self.template.expand_default_value_pattern(length=len(self.body)) + if not default: + sm = SequenceMatcher(a=b'\xff'*len(self.body), b=self.body) + else: + if default == self.body: + # 100% match: retrun an empty tuple list to make eUICC use the default + return [] + sm = SequenceMatcher(a=default, b=self.body) + else: + # no template at all: we can only remove padding + sm = SequenceMatcher(a=b'\xff'*len(self.body), b=self.body) + matching_blocks = sm.get_matching_blocks() + # we can only make use of matches that have the same offset in 'a' and 'b' + matching_blocks = [x for x in matching_blocks if x.size > 0 and x.a == x.b] + non_matching_blocks = NonMatch.from_matchlist(matching_blocks, self.file_size) + ret = [] + cur = 0 + for block in non_matching_blocks: + ret.append(('fillFileOffset', block.a - cur)) + ret.append(('fillFileContent', self.body[block.a:block.a+block.size])) + return ret

def __str__(self) -> str: return "File(%s)" % self.pe_name diff --git a/tests/unittests/test_esim_saip.py b/tests/unittests/test_esim_saip.py index e7e324d..edf6d8d 100755 --- a/tests/unittests/test_esim_saip.py +++ b/tests/unittests/test_esim_saip.py @@ -90,5 +90,34 @@ self.assertTrue(oid.OID('1.0.1') > oid.OID('1.0')) self.assertTrue(oid.OID('1.0.2') > oid.OID('1.0.1'))

+class NonMatchTest(unittest.TestCase): + def test_nonmatch(self): + # non-matches before, in between and after matches + match_list = [Match(a=10, b=10, size=5), Match(a=20, b=20, size=4)] + nm_list = NonMatch.from_matchlist(match_list, 26) + self.assertEqual(nm_list, [NonMatch(a=0, b=0, size=10), NonMatch(a=15, b=15, size=5), + NonMatch(a=24, b=24, size=2)]) + + def test_nonmatch_beg(self): + # single match at beginning + match_list = [Match(a=0, b=0, size=5)] + nm_list = NonMatch.from_matchlist(match_list, 20) + self.assertEqual(nm_list, [NonMatch(a=5, b=5, size=15)]) + + def test_nonmatch_end(self): + # single match at end + match_list = [Match(a=19, b=19, size=5)] + nm_list = NonMatch.from_matchlist(match_list, 24) + self.assertEqual(nm_list, [NonMatch(a=0, b=0, size=19)]) + + def test_nonmatch_none(self): + # no match at all + match_list = [] + nm_list = NonMatch.from_matchlist(match_list, 24) + self.assertEqual(nm_list, [NonMatch(a=0, b=0, size=24)]) + + + + if __name__ == "__main__": unittest.main()