mirror of
https://github.com/google/bumble.git
synced 2026-05-08 03:58:01 +00:00
Merge pull request #919 from zxzxwu/sdp
SDP: Move parser functions to parser class
This commit is contained in:
Josh Wu
581
bumble/sdp.py
581
bumble/sdp.py
@@ -20,7 +20,6 @@ from __future__ import annotations
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import asyncio
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import logging
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import struct
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import threading
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from collections.abc import Iterable, Sequence
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from dataclasses import dataclass, field
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from typing import TYPE_CHECKING, Any, ClassVar, NewType, TypeVar
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@@ -49,7 +48,6 @@ logger = logging.getLogger(__name__)
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# prevent a malicious peer from crashing the process via a deeply nested PDU.
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# 32 levels is well beyond anything a legitimate service record uses.
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_MAX_DATA_ELEMENT_NESTING = 32
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_parse_state = threading.local()
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# -----------------------------------------------------------------------------
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@@ -156,32 +154,6 @@ class DataElement:
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ALTERNATIVE = Type.ALTERNATIVE
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URL = Type.URL
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TYPE_CONSTRUCTORS = {
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NIL: lambda x: DataElement(DataElement.NIL, None),
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UNSIGNED_INTEGER: lambda x, y: DataElement(
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DataElement.UNSIGNED_INTEGER,
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DataElement.unsigned_integer_from_bytes(x),
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value_size=y,
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),
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SIGNED_INTEGER: lambda x, y: DataElement(
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DataElement.SIGNED_INTEGER,
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DataElement.signed_integer_from_bytes(x),
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value_size=y,
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),
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UUID: lambda x: DataElement(
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DataElement.UUID, core.UUID.from_bytes(bytes(reversed(x)))
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),
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TEXT_STRING: lambda x: DataElement(DataElement.TEXT_STRING, x),
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BOOLEAN: lambda x: DataElement(DataElement.BOOLEAN, x[0] == 1),
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SEQUENCE: lambda x: DataElement(
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DataElement.SEQUENCE, DataElement.list_from_bytes(x)
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),
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ALTERNATIVE: lambda x: DataElement(
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DataElement.ALTERNATIVE, DataElement.list_from_bytes(x)
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),
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URL: lambda x: DataElement(DataElement.URL, x.decode('utf8')),
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}
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type: Type
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value: Any
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value_size: int | None = None
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@@ -198,289 +170,354 @@ class DataElement:
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'integer types must have a value size specified'
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)
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@staticmethod
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def nil() -> DataElement:
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return DataElement(DataElement.NIL, None)
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@classmethod
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def nil(cls) -> DataElement:
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return cls(cls.NIL, None)
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@staticmethod
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def unsigned_integer(value: int, value_size: int) -> DataElement:
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return DataElement(DataElement.UNSIGNED_INTEGER, value, value_size)
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@classmethod
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def unsigned_integer(cls, value: int, value_size: int) -> DataElement:
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return cls(cls.UNSIGNED_INTEGER, value, value_size)
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@staticmethod
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def unsigned_integer_8(value: int) -> DataElement:
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return DataElement(DataElement.UNSIGNED_INTEGER, value, value_size=1)
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@classmethod
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def unsigned_integer_8(cls, value: int) -> DataElement:
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return cls(cls.UNSIGNED_INTEGER, value, value_size=1)
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@staticmethod
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def unsigned_integer_16(value: int) -> DataElement:
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return DataElement(DataElement.UNSIGNED_INTEGER, value, value_size=2)
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@classmethod
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def unsigned_integer_16(cls, value: int) -> DataElement:
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return cls(cls.UNSIGNED_INTEGER, value, value_size=2)
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@staticmethod
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def unsigned_integer_32(value: int) -> DataElement:
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return DataElement(DataElement.UNSIGNED_INTEGER, value, value_size=4)
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@classmethod
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def unsigned_integer_32(cls, value: int) -> DataElement:
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return cls(cls.UNSIGNED_INTEGER, value, value_size=4)
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@staticmethod
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def signed_integer(value: int, value_size: int) -> DataElement:
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return DataElement(DataElement.SIGNED_INTEGER, value, value_size)
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@classmethod
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def signed_integer(cls, value: int, value_size: int) -> DataElement:
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return cls(cls.SIGNED_INTEGER, value, value_size)
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@staticmethod
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def signed_integer_8(value: int) -> DataElement:
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return DataElement(DataElement.SIGNED_INTEGER, value, value_size=1)
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@classmethod
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def signed_integer_8(cls, value: int) -> DataElement:
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return cls(cls.SIGNED_INTEGER, value, value_size=1)
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@staticmethod
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def signed_integer_16(value: int) -> DataElement:
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return DataElement(DataElement.SIGNED_INTEGER, value, value_size=2)
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@classmethod
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def signed_integer_16(cls, value: int) -> DataElement:
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return cls(cls.SIGNED_INTEGER, value, value_size=2)
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@staticmethod
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def signed_integer_32(value: int) -> DataElement:
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return DataElement(DataElement.SIGNED_INTEGER, value, value_size=4)
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@classmethod
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def signed_integer_32(cls, value: int) -> DataElement:
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return cls(cls.SIGNED_INTEGER, value, value_size=4)
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@staticmethod
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def uuid(value: core.UUID) -> DataElement:
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return DataElement(DataElement.UUID, value)
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@classmethod
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def uuid(cls, value: core.UUID) -> DataElement:
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return cls(cls.UUID, value)
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@staticmethod
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def text_string(value: bytes) -> DataElement:
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return DataElement(DataElement.TEXT_STRING, value)
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@classmethod
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def text_string(cls, value: bytes) -> DataElement:
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return cls(cls.TEXT_STRING, value)
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@staticmethod
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def boolean(value: bool) -> DataElement:
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return DataElement(DataElement.BOOLEAN, value)
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@classmethod
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def boolean(cls, value: bool) -> DataElement:
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return cls(cls.BOOLEAN, value)
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@staticmethod
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def sequence(value: Iterable[DataElement]) -> DataElement:
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return DataElement(DataElement.SEQUENCE, value)
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@classmethod
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def sequence(cls, value: Iterable[DataElement]) -> DataElement:
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return cls(cls.SEQUENCE, value)
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@staticmethod
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def alternative(value: Iterable[DataElement]) -> DataElement:
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return DataElement(DataElement.ALTERNATIVE, value)
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@classmethod
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def alternative(cls, value: Iterable[DataElement]) -> DataElement:
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return cls(cls.ALTERNATIVE, value)
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@staticmethod
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def url(value: str) -> DataElement:
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return DataElement(DataElement.URL, value)
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@classmethod
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def url(cls, value: str) -> DataElement:
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return cls(cls.URL, value)
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@staticmethod
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def unsigned_integer_from_bytes(data):
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if len(data) == 1:
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return data[0]
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@classmethod
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def unsigned_integer_from_bytes(cls, data: bytes, offset: int, length: int) -> int:
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match length:
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case 1:
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return data[offset]
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case 2:
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return struct.unpack_from('>H', data, offset)[0]
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case 4:
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return struct.unpack_from('>I', data, offset)[0]
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case 8:
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return struct.unpack_from('>Q', data, offset)[0]
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case invalid_length:
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raise InvalidPacketError(f'invalid integer length {invalid_length}')
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if len(data) == 2:
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return struct.unpack('>H', data)[0]
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@classmethod
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def signed_integer_from_bytes(cls, data: bytes, offset: int, length: int) -> int:
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match length:
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case 1:
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return struct.unpack_from('b', data, offset)[0]
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case 2:
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return struct.unpack_from('>h', data, offset)[0]
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case 4:
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return struct.unpack_from('>i', data, offset)[0]
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case 8:
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return struct.unpack_from('>q', data, offset)[0]
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case invalid_length:
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raise InvalidPacketError(f'invalid integer length {invalid_length}')
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if len(data) == 4:
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return struct.unpack('>I', data)[0]
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@classmethod
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def parse_from_bytes(cls, data: bytes, offset: int) -> tuple[int, DataElement]:
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parser = DataElementParser(data, offset)
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element = parser.parse_next()
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return parser.offset, element
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if len(data) == 8:
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return struct.unpack('>Q', data)[0]
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@classmethod
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def from_bytes(cls, data: bytes) -> DataElement:
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return DataElementParser(data).parse_next()
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raise InvalidPacketError(f'invalid integer length {len(data)}')
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@staticmethod
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def signed_integer_from_bytes(data):
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if len(data) == 1:
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return struct.unpack('b', data)[0]
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if len(data) == 2:
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return struct.unpack('>h', data)[0]
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if len(data) == 4:
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return struct.unpack('>i', data)[0]
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if len(data) == 8:
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return struct.unpack('>q', data)[0]
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raise InvalidPacketError(f'invalid integer length {len(data)}')
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@staticmethod
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def list_from_bytes(data):
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depth = getattr(_parse_state, "depth", 0)
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if depth >= _MAX_DATA_ELEMENT_NESTING:
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raise InvalidPacketError(
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f"SDP data element nesting exceeds max depth "
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f"({_MAX_DATA_ELEMENT_NESTING})"
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)
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_parse_state.depth = depth + 1
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try:
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elements = []
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while data:
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element = DataElement.from_bytes(data)
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elements.append(element)
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data = data[len(bytes(element)) :]
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return elements
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finally:
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_parse_state.depth = depth
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@staticmethod
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def parse_from_bytes(data, offset):
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element = DataElement.from_bytes(data[offset:])
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return offset + len(bytes(element)), element
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@staticmethod
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def from_bytes(data):
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element_type = data[0] >> 3
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size_index = data[0] & 7
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value_offset = 0
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if size_index == 0:
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if element_type == DataElement.NIL:
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value_size = 0
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else:
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value_size = 1
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elif size_index == 1:
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value_size = 2
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elif size_index == 2:
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value_size = 4
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elif size_index == 3:
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value_size = 8
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elif size_index == 4:
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value_size = 16
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elif size_index == 5:
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value_size = data[1]
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value_offset = 1
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elif size_index == 6:
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value_size = struct.unpack('>H', data[1:3])[0]
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value_offset = 2
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else: # size_index == 7
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value_size = struct.unpack('>I', data[1:5])[0]
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value_offset = 4
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value_data = data[1 + value_offset : 1 + value_offset + value_size]
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constructor = DataElement.TYPE_CONSTRUCTORS.get(element_type)
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if constructor:
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if element_type in (
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DataElement.UNSIGNED_INTEGER,
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DataElement.SIGNED_INTEGER,
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):
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result = constructor(value_data, value_size)
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else:
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result = constructor(value_data)
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else:
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result = DataElement(element_type, value_data)
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result._bytes = data[
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: 1 + value_offset + value_size
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] # Keep a copy so we can re-serialize to an exact replica
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return result
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def __bytes__(self):
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def __bytes__(self) -> bytes:
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# Return early if we have a cache
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if self._bytes:
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return self._bytes
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if self.type == DataElement.NIL:
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data = b''
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elif self.type == DataElement.UNSIGNED_INTEGER:
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if self.value < 0:
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raise InvalidArgumentError('UNSIGNED_INTEGER cannot be negative')
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match self.type:
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case DataElement.NIL:
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data = b''
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case DataElement.UNSIGNED_INTEGER:
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if self.value < 0:
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raise InvalidArgumentError('UNSIGNED_INTEGER cannot be negative')
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if self.value_size == 1:
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data = struct.pack('B', self.value)
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elif self.value_size == 2:
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data = struct.pack('>H', self.value)
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elif self.value_size == 4:
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data = struct.pack('>I', self.value)
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elif self.value_size == 8:
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data = struct.pack('>Q', self.value)
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else:
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raise InvalidArgumentError('invalid value_size')
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elif self.type == DataElement.SIGNED_INTEGER:
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if self.value_size == 1:
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data = struct.pack('b', self.value)
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elif self.value_size == 2:
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data = struct.pack('>h', self.value)
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elif self.value_size == 4:
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data = struct.pack('>i', self.value)
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elif self.value_size == 8:
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data = struct.pack('>q', self.value)
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else:
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raise InvalidArgumentError('invalid value_size')
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elif self.type == DataElement.UUID:
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data = bytes(reversed(bytes(self.value)))
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elif self.type == DataElement.URL:
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data = self.value.encode('utf8')
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elif self.type == DataElement.BOOLEAN:
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data = bytes([1 if self.value else 0])
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elif self.type in (DataElement.SEQUENCE, DataElement.ALTERNATIVE):
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data = b''.join([bytes(element) for element in self.value])
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else:
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data = self.value
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match self.value_size:
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case 1:
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data = struct.pack('B', self.value)
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case 2:
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data = struct.pack('>H', self.value)
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case 4:
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data = struct.pack('>I', self.value)
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case 8:
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data = struct.pack('>Q', self.value)
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case invalid_length:
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raise InvalidArgumentError(
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f'invalid value_size of {invalid_length}'
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)
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case DataElement.SIGNED_INTEGER:
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match self.value_size:
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case 1:
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data = struct.pack('b', self.value)
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case 2:
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data = struct.pack('>h', self.value)
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case 4:
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data = struct.pack('>i', self.value)
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case 8:
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data = struct.pack('>q', self.value)
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case invalid_length:
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raise InvalidArgumentError(
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f'invalid value_size of {invalid_length}'
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)
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case DataElement.UUID:
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data = bytes(self.value)[::-1]
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case DataElement.URL:
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data = self.value.encode('utf8')
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case DataElement.BOOLEAN:
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data = bytes([1 if self.value else 0])
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case DataElement.SEQUENCE | DataElement.ALTERNATIVE:
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data = b''.join([bytes(element) for element in self.value])
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case _:
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data = self.value
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size = len(data)
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size_bytes = b''
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if self.type == DataElement.NIL:
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if size != 0:
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raise InvalidArgumentError('NIL must be empty')
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size_index = 0
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elif self.type in (
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DataElement.UNSIGNED_INTEGER,
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DataElement.SIGNED_INTEGER,
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DataElement.UUID,
|
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):
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if size <= 1:
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match self.type:
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case DataElement.NIL:
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if size != 0:
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raise InvalidArgumentError('NIL must be empty')
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size_index = 0
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elif size == 2:
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size_index = 1
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elif size == 4:
|
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size_index = 2
|
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elif size == 8:
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size_index = 3
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elif size == 16:
|
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size_index = 4
|
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else:
|
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raise InvalidArgumentError('invalid data size')
|
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elif self.type in (
|
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DataElement.TEXT_STRING,
|
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DataElement.SEQUENCE,
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DataElement.ALTERNATIVE,
|
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DataElement.URL,
|
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):
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if size <= 0xFF:
|
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size_index = 5
|
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size_bytes = bytes([size])
|
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elif size <= 0xFFFF:
|
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size_index = 6
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size_bytes = struct.pack('>H', size)
|
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elif size <= 0xFFFFFFFF:
|
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size_index = 7
|
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size_bytes = struct.pack('>I', size)
|
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else:
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raise InvalidArgumentError('invalid data size')
|
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elif self.type == DataElement.BOOLEAN:
|
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if size != 1:
|
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raise InvalidArgumentError('boolean must be 1 byte')
|
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size_index = 0
|
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else:
|
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raise RuntimeError("internal error - self.type not supported")
|
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case (
|
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DataElement.UNSIGNED_INTEGER
|
||||
| DataElement.SIGNED_INTEGER
|
||||
| DataElement.UUID
|
||||
):
|
||||
if size <= 1:
|
||||
size_index = 0
|
||||
elif size == 2:
|
||||
size_index = 1
|
||||
elif size == 4:
|
||||
size_index = 2
|
||||
elif size == 8:
|
||||
size_index = 3
|
||||
elif size == 16:
|
||||
size_index = 4
|
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else:
|
||||
raise InvalidArgumentError('invalid data size')
|
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case (
|
||||
DataElement.TEXT_STRING
|
||||
| DataElement.SEQUENCE
|
||||
| DataElement.ALTERNATIVE
|
||||
| DataElement.URL
|
||||
):
|
||||
if size <= 0xFF:
|
||||
size_index = 5
|
||||
size_bytes = bytes([size])
|
||||
elif size <= 0xFFFF:
|
||||
size_index = 6
|
||||
size_bytes = struct.pack('>H', size)
|
||||
elif size <= 0xFFFFFFFF:
|
||||
size_index = 7
|
||||
size_bytes = struct.pack('>I', size)
|
||||
else:
|
||||
raise InvalidArgumentError('invalid data size')
|
||||
case DataElement.BOOLEAN:
|
||||
if size != 1:
|
||||
raise InvalidArgumentError('boolean must be 1 byte')
|
||||
size_index = 0
|
||||
case unsupported_type:
|
||||
raise core.InvalidPacketError(
|
||||
f"internal error - {unsupported_type} not supported"
|
||||
)
|
||||
|
||||
self._bytes = bytes([self.type << 3 | size_index]) + size_bytes + data
|
||||
return self._bytes
|
||||
|
||||
def to_string(self, pretty=False, indentation=0):
|
||||
def to_string(self, pretty: bool = False, indentation: int = 0) -> str:
|
||||
prefix = ' ' * indentation
|
||||
type_name = self.type.name
|
||||
if self.type == DataElement.NIL:
|
||||
value_string = ''
|
||||
elif self.type in (DataElement.SEQUENCE, DataElement.ALTERNATIVE):
|
||||
container_separator = '\n' if pretty else ''
|
||||
element_separator = '\n' if pretty else ','
|
||||
elements = [
|
||||
element.to_string(pretty, indentation + 1 if pretty else 0)
|
||||
for element in self.value
|
||||
]
|
||||
value_string = (
|
||||
f'[{container_separator}'
|
||||
f'{element_separator.join(elements)}'
|
||||
f'{container_separator}{prefix}]'
|
||||
)
|
||||
elif self.type in (DataElement.UNSIGNED_INTEGER, DataElement.SIGNED_INTEGER):
|
||||
value_string = f'{self.value}#{self.value_size}'
|
||||
elif isinstance(self.value, DataElement):
|
||||
value_string = self.value.to_string(pretty, indentation)
|
||||
else:
|
||||
value_string = str(self.value)
|
||||
match self.type:
|
||||
case DataElement.NIL:
|
||||
value_string = ''
|
||||
case DataElement.SEQUENCE | DataElement.ALTERNATIVE:
|
||||
container_separator = '\n' if pretty else ''
|
||||
element_separator = '\n' if pretty else ','
|
||||
elements = [
|
||||
element.to_string(pretty, indentation + 1 if pretty else 0)
|
||||
for element in self.value
|
||||
]
|
||||
value_string = (
|
||||
f'[{container_separator}'
|
||||
f'{element_separator.join(elements)}'
|
||||
f'{container_separator}{prefix}]'
|
||||
)
|
||||
case DataElement.UNSIGNED_INTEGER | DataElement.SIGNED_INTEGER:
|
||||
value_string = f'{self.value}#{self.value_size}'
|
||||
case _:
|
||||
if isinstance(self.value, DataElement):
|
||||
value_string = self.value.to_string(pretty, indentation)
|
||||
else:
|
||||
value_string = str(self.value)
|
||||
return f'{prefix}{type_name}({value_string})'
|
||||
|
||||
def __str__(self):
|
||||
def __str__(self) -> str:
|
||||
return self.to_string()
|
||||
|
||||
|
||||
class DataElementParser:
|
||||
def __init__(
|
||||
self, data: bytes, offset: int = 0, max_depth: int = _MAX_DATA_ELEMENT_NESTING
|
||||
) -> None:
|
||||
self.data = data
|
||||
self.offset = offset
|
||||
self.depth = 0
|
||||
self.max_depth = max_depth
|
||||
|
||||
def parse_next(self) -> DataElement:
|
||||
if self.offset >= len(self.data):
|
||||
raise core.InvalidStateError(
|
||||
f"offset {self.offset} exceeds len(data) {len(self.data)}"
|
||||
)
|
||||
start_offset = self.offset
|
||||
element_type = DataElement.Type(self.data[self.offset] >> 3)
|
||||
size_index = self.data[self.offset] & 7
|
||||
self.offset += 1
|
||||
|
||||
value_size: int
|
||||
match size_index:
|
||||
case 0:
|
||||
if element_type == DataElement.NIL:
|
||||
value_size = 0
|
||||
else:
|
||||
value_size = 1
|
||||
case 1:
|
||||
value_size = 2
|
||||
case 2:
|
||||
value_size = 4
|
||||
case 3:
|
||||
value_size = 8
|
||||
case 4:
|
||||
value_size = 16
|
||||
case 5:
|
||||
value_size = self.data[self.offset]
|
||||
self.offset += 1
|
||||
case 6:
|
||||
value_size = struct.unpack_from('>H', self.data, self.offset)[0]
|
||||
self.offset += 2
|
||||
case 7:
|
||||
value_size = struct.unpack_from('>I', self.data, self.offset)[0]
|
||||
self.offset += 4
|
||||
case _:
|
||||
raise core.UnreachableError()
|
||||
|
||||
value_start = self.offset
|
||||
value_end = self.offset + value_size
|
||||
|
||||
match element_type:
|
||||
case DataElement.NIL:
|
||||
result = DataElement(DataElement.NIL, None)
|
||||
case DataElement.UNSIGNED_INTEGER:
|
||||
result = DataElement(
|
||||
DataElement.UNSIGNED_INTEGER,
|
||||
DataElement.unsigned_integer_from_bytes(
|
||||
self.data, value_start, value_size
|
||||
),
|
||||
value_size=value_size,
|
||||
)
|
||||
case DataElement.SIGNED_INTEGER:
|
||||
result = DataElement(
|
||||
DataElement.SIGNED_INTEGER,
|
||||
DataElement.signed_integer_from_bytes(
|
||||
self.data, value_start, value_size
|
||||
),
|
||||
value_size=value_size,
|
||||
)
|
||||
case DataElement.UUID:
|
||||
result = DataElement(
|
||||
DataElement.UUID,
|
||||
core.UUID.from_bytes(self.data[value_start:value_end][::-1]),
|
||||
)
|
||||
case DataElement.TEXT_STRING:
|
||||
result = DataElement(
|
||||
DataElement.TEXT_STRING, self.data[value_start:value_end]
|
||||
)
|
||||
case DataElement.BOOLEAN:
|
||||
result = DataElement(DataElement.BOOLEAN, self.data[value_start] == 1)
|
||||
case DataElement.SEQUENCE | DataElement.ALTERNATIVE:
|
||||
self.offset = value_start
|
||||
result = DataElement(
|
||||
element_type,
|
||||
self._list_from_bytes(value_end),
|
||||
)
|
||||
if self.offset != value_end:
|
||||
logger.warning(
|
||||
"Expect parsing until offset %d, but ends at %d",
|
||||
value_end,
|
||||
self.offset,
|
||||
)
|
||||
case DataElement.URL:
|
||||
result = DataElement(
|
||||
DataElement.URL, self.data[value_start:value_end].decode('utf8')
|
||||
)
|
||||
case other_type:
|
||||
result = DataElement(other_type, self.data[value_start:value_end])
|
||||
|
||||
self.offset = value_end
|
||||
result._bytes = self.data[start_offset:value_end]
|
||||
|
||||
return result
|
||||
|
||||
def _list_from_bytes(self, end_offset: int) -> list[DataElement]:
|
||||
if self.depth >= self.max_depth:
|
||||
raise InvalidPacketError(
|
||||
f"SDP data element nesting exceeds max depth " f"({self.max_depth})"
|
||||
)
|
||||
self.depth += 1
|
||||
elements = []
|
||||
while self.offset < end_offset:
|
||||
elements.append(self.parse_next())
|
||||
self.depth -= 1
|
||||
return elements
|
||||
|
||||
|
||||
# -----------------------------------------------------------------------------
|
||||
@dataclass
|
||||
class ServiceAttribute:
|
||||
|
||||
Reference in New Issue
Block a user