105 lines
3.2 KiB
Python
105 lines
3.2 KiB
Python
# This file is part of Extractor.
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# Copyright (C) 2021 Security Research Labs GmbH
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# SPDX-License-Identifier: Apache-2.0
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from typing import TypeVar, Type
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from io import BytesIO
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from construct import Struct, Construct # type: ignore
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# TypeVar is required so that parse returns the right type (of the sub-class).
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# https://stackoverflow.com/a/46064289
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# noinspection PyTypeChecker
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T = TypeVar('T', bound='TypedContainer')
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class TypedContainer:
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"""
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Base class for a typed struct for use with construct. Usage instructions:
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* Make your own class with TypedContainer as superclass
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* Define instance fields with typing (e.g. bytes or int)
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* Set the class variable construct_struct to the actual construct Struct() definition
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"""
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construct_struct: Struct
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@classmethod
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def parse(cls: Type[T], buf: bytes) -> T:
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"""
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Parses a buffer
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:param buf:
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:return:
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"""
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return cls.parse_stream(BytesIO(buf))
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@classmethod
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def parse_stream(cls: Type[T], stream):
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self = cls()
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construct_container = cls.construct_struct.parse_stream(stream)
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for k, v in dict(construct_container).items():
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self.__setattr__(k, v)
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return self
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@classmethod
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def sizeof(cls):
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return cls.construct_struct.sizeof()
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def build(self) -> bytes:
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return self.__class__.construct_struct.build(self.__dict__)
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def __str__(self):
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string_list = [self.__class__.__name__]
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for k, v in sorted(self.__dict__.items()):
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string_list.append(" %s = %r" % (k, v))
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return "\n".join(string_list)
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def __repr__(self):
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field_params = []
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# Use correct order
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for field in self.construct_struct.subcons:
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field_params.append("%s=%r" % (field.name, self.__getattribute__(field.name)))
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return "%s(%s)" % (self.__class__.__name__, ", ".join(field_params))
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def __eq__(self, other: T):
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if type(self) is not type(other):
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return False
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for field in self.construct_struct.subcons:
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if self.__getattribute__(field.name) != other.__getattribute__(field.name):
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return False
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return True
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@classmethod
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def as_inner_type(cls):
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return InnerTypedContainer(cls)
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class InnerTypedContainer(Construct):
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inner_type: T
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def __init__(self, inner_type):
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super().__init__()
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self.inner_type = inner_type
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def _parse(self, stream, context, path):
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return self.inner_type.parse_stream(stream)
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def _build(self, obj, stream, context, path):
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buf = obj.build()
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stream.write(buf)
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def _sizeof(self, context, path):
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return self.inner_type.sizeof()
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