[M] Change in pysim[master]: construct/tlv: Pass optional 'context' into construct decoder/encoder

laforge has submitted this change. ( https://gerrit.osmocom.org/c/pysim/+/35380?usp=email ) Change subject: construct/tlv: Pass optional 'context' into construct decoder/encoder ...................................................................... construct/tlv: Pass optional 'context' into construct decoder/encoder The context is some opaque dictionary that can be used by the constructs; let's allow the caller of parse_construct, from_bytes, from_tlv to specify it. Also, when decoding a TLV_IE_Collection, pass the decode results of existing siblings via the construct. Change-Id: I021016aaa09cddf9d36521c1a54b468ec49ff54d --- M pySim/construct.py M pySim/tlv.py 2 files changed, 52 insertions(+), 31 deletions(-) Approvals: Jenkins Builder: Verified laforge: Looks good to me, approved diff --git a/pySim/construct.py b/pySim/construct.py index 31caf0e..cef9557 100644 --- a/pySim/construct.py +++ b/pySim/construct.py @@ -200,13 +200,16 @@ return r -def parse_construct(c, raw_bin_data: bytes, length: typing.Optional[int] = None, exclude_prefix: str = '_'): +def parse_construct(c, raw_bin_data: bytes, length: typing.Optional[int] = None, exclude_prefix: str = '_', context: dict = {}): """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) + parsed = c.parse(raw_bin_data, total_len=length, **context) return normalize_construct(parsed) +def build_construct(c, decoded_data, context: dict = {}): + """Helper function to handle total_len.""" + return c.build(decoded_data, total_len=None, **context) # here we collect some shared / common definitions of data types LV = Prefixed(Int8ub, HexAdapter(GreedyBytes)) diff --git a/pySim/tlv.py b/pySim/tlv.py index c85d92b..6ea7dd1 100644 --- a/pySim/tlv.py +++ b/pySim/tlv.py @@ -26,7 +26,7 @@ from pySim.utils import bertlv_parse_one, comprehensiontlv_parse_one from pySim.utils import bertlv_parse_tag_raw, comprehensiontlv_parse_tag_raw -from pySim.construct import parse_construct, LV, HexAdapter, BcdAdapter, BitsRFU, GsmStringAdapter +from pySim.construct import build_construct, parse_construct, LV, HexAdapter, BcdAdapter, BitsRFU, GsmStringAdapter from pySim.exceptions import * import inspect @@ -84,15 +84,15 @@ self.decoded = None self._construct = None - def to_bytes(self) -> bytes: + def to_bytes(self, context: dict = {}) -> bytes: """Convert from internal representation to binary bytes. Store the binary result in the internal state and return it.""" if self.decoded == None: do = b'' elif self._construct: - do = self._construct.build(self.decoded, total_len=None) + do = build_construct(self._construct, self.decoded, context) elif self.__class__._construct: - do = self.__class__._construct.build(self.decoded, total_len=None) + do = build_construct(self.__class__._construct, self.decoded, context) else: do = self._to_bytes() self.encoded = do @@ -102,16 +102,16 @@ def _to_bytes(self): raise NotImplementedError('%s._to_bytes' % type(self).__name__) - def from_bytes(self, do: bytes): + def from_bytes(self, do: bytes, context: dict = {}): """Convert from binary bytes to internal representation. Store the decoded result in the internal state and return it.""" self.encoded = do if self.encoded == b'': self.decoded = None elif self._construct: - self.decoded = parse_construct(self._construct, do) + self.decoded = parse_construct(self._construct, do, context=context) elif self.__class__._construct: - self.decoded = parse_construct(self.__class__._construct, do) + self.decoded = parse_construct(self.__class__._construct, do, context=context) else: self.decoded = self._from_bytes(do) return self.decoded @@ -174,27 +174,27 @@ return False @abc.abstractmethod - def to_ie(self) -> bytes: + def to_ie(self, context: dict = {}) -> bytes: """Convert the internal representation to entire IE including IE header.""" - def to_bytes(self) -> bytes: + def to_bytes(self, context: dict = {}) -> bytes: """Convert the internal representation *of the value part* to binary bytes.""" if self.is_constructed(): # concatenate the encoded IE of all children to form the value part out = b'' for c in self.children: - out += c.to_ie() + out += c.to_ie(context=context) return out else: - return super().to_bytes() + return super().to_bytes(context=context) - def from_bytes(self, do: bytes): + def from_bytes(self, do: bytes, context: dict = {}): """Parse *the value part* from binary bytes to internal representation.""" if self.nested_collection: - self.children = self.nested_collection.from_bytes(do) + self.children = self.nested_collection.from_bytes(do, context=context) else: self.children = [] - return super().from_bytes(do) + return super().from_bytes(do, context=context) class TLV_IE(IE): @@ -226,15 +226,15 @@ """Encode the length part assuming a certain binary value. Must be provided by derived (TLV format specific) class.""" - def to_ie(self): - return self.to_tlv() + def to_ie(self, context: dict = {}): + return self.to_tlv(context=context) - def to_tlv(self): + def to_tlv(self, context: dict = {}): """Convert the internal representation to binary TLV bytes.""" - val = self.to_bytes() + val = self.to_bytes(context=context) return self._encode_tag() + self._encode_len(val) + val - def from_tlv(self, do: bytes): + def from_tlv(self, do: bytes, context: dict = {}): if len(do) == 0: return {}, b'' (rawtag, remainder) = self.__class__._parse_tag_raw(do) @@ -248,7 +248,7 @@ else: value = do remainder = b'' - dec = self.from_bytes(value) + dec = self.from_bytes(value, context=context) return dec, remainder @@ -343,7 +343,7 @@ else: raise TypeError - def from_bytes(self, binary: bytes) -> List[TLV_IE]: + def from_bytes(self, binary: bytes, context: dict = {}) -> List[TLV_IE]: """Create a list of TLV_IEs from the collection based on binary input data. Args: binary : binary bytes of encoded data @@ -357,6 +357,7 @@ first = next(iter(self.members_by_tag.values())) # iterate until no binary trailer is left while len(remainder): + context['siblings'] = res # obtain the tag at the start of the remainder tag, r = first._parse_tag_raw(remainder) if tag == None: @@ -365,7 +366,7 @@ cls = self.members_by_tag[tag] # create an instance and parse accordingly inst = cls() - dec, remainder = inst.from_tlv(remainder) + dec, remainder = inst.from_tlv(remainder, context=context) res.append(inst) else: # unknown tag; create the related class on-the-fly using the same base class @@ -376,7 +377,7 @@ cls._to_bytes = lambda s: bytes.fromhex(s.decoded['raw']) # create an instance and parse accordingly inst = cls() - dec, remainder = inst.from_tlv(remainder) + dec, remainder = inst.from_tlv(remainder, context=context) res.append(inst) self.children = res return res @@ -413,17 +414,18 @@ # self.__class__.__name__, but that is usually some meaningless auto-generated collection name. return [x.to_dict() for x in self.children] - def to_bytes(self): + def to_bytes(self, context: dict = {}): out = b'' + context['siblings'] = self.children for c in self.children: - out += c.to_tlv() + out += c.to_tlv(context=context) return out - def from_tlv(self, do): - return self.from_bytes(do) + def from_tlv(self, do, context: dict = {}): + return self.from_bytes(do, context=context) - def to_tlv(self): - return self.to_bytes() + def to_tlv(self, context: dict = {}): + return self.to_bytes(context=context) def flatten_dict_lists(inp): -- To view, visit https://gerrit.osmocom.org/c/pysim/+/35380?usp=email To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: pysim Gerrit-Branch: master Gerrit-Change-Id: I021016aaa09cddf9d36521c1a54b468ec49ff54d Gerrit-Change-Number: 35380 Gerrit-PatchSet: 3 Gerrit-Owner: laforge <laforge(a)osmocom.org> Gerrit-Reviewer: Jenkins Builder Gerrit-Reviewer: dexter <pmaier(a)sysmocom.de> Gerrit-Reviewer: laforge <laforge(a)osmocom.org> Gerrit-MessageType: merged