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#
# Copyright 2022 aiohomekit team
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
from __future__ import annotations
from collections.abc import Iterable
from enum import Enum
import logging
import struct
from aiohomekit.enum import EnumWithDescription
logger = logging.getLogger(__name__)
STRUCT_BBBH_PACK = struct.Struct("<BBBH").pack
STRUCT_BBB_PACK = struct.Struct("<BBB").pack
STRUCT_BBB_UNPACK = struct.Struct("<BBB").unpack
STRUCT_H_PACK = struct.Struct("<H").pack
STRUCT_H_UNPACK = struct.Struct("<H").unpack
STRUCT_BB_PACK = struct.Struct("<BB").pack
STRUCT_BB_UNPACK = struct.Struct("<BB").unpack
class OpCode(Enum):
CHAR_SIG_READ = 0x01
CHAR_WRITE = 0x02
CHAR_READ = 0x03
CHAR_TIMED_WRITE = 0x04
CHAR_EXEC_WRITE = 0x05
SERV_SIG_READ = 0x06
CHAR_CONFIG = 0x07
PROTOCOL_CONFIG = 0x08
class PDUStatus(EnumWithDescription):
SUCCESS = 0, "Success"
UNSUPPORTED_PDU = 1, "Unsupported PDU"
MAX_PROCEDURES = 2, "Max procedures"
INSUFFICIENT_AUTHORIZATION = 3, "Insufficient authorization"
INVALID_INSTANCE_ID = 4, "Invalid instance ID"
INSUFFICIENT_AUTHENTICATION = 5, "Insufficient authentication"
INVALID_REQUEST = 6, "Invalid request"
def encode_pdu(
opcode: OpCode,
tid: int,
iid: int,
data: bytes | None = None,
fragment_size: int = 512,
) -> Iterable[bytes]:
"""
Encodes a PDU.
The header is required, but the body (including length) is optional.
For BLE, the PDU must be fragmented to fit into ATT_MTU. The default here is 512.
In a secure session this drops to 496 (16 bytes for the encryption). Some devices
drop this quite a bit.
"""
retval = STRUCT_BBBH_PACK(0, opcode.value, tid, iid)
if not data:
yield retval
return
# Full header + body size + data
next_size = fragment_size - 7
yield bytes(retval + STRUCT_H_PACK(len(data)) + data[:next_size])
data = data[next_size:]
# Control + tid + data
next_size = fragment_size - 2
for i in range(0, len(data), next_size):
yield STRUCT_BB_PACK(0x80, tid) + data[i : i + next_size]
def decode_pdu(expected_tid: int, data: bytes) -> tuple[PDUStatus, bool, bytes]:
control, tid, status = STRUCT_BBB_UNPACK(data[:3])
status = PDUStatus(status)
logger.debug(
"Got PDU %s: TID %02x (Expected: %02x), Status:%s, Len:%d - %s",
control,
tid,
expected_tid,
status,
len(data) - 5,
data,
)
if tid != expected_tid:
raise ValueError(
f"Expected transaction {expected_tid} but got transaction {tid}"
)
if status != PDUStatus.SUCCESS:
# We can't currently raise here or it will break the encryption
# stream
logger.warning(
f"Transaction {tid} failed with error {status} ({status.description})"
)
if len(data) < 5:
return status, 0, b""
expected_length = STRUCT_H_UNPACK(data[3:5])[0]
data = data[5:]
return status, expected_length, data
def decode_pdu_continuation(expected_tid, data):
control, tid = STRUCT_BB_UNPACK(data[:2])
logger.debug(
"Got PDU %x: TID %02x (Expected: %02x) Len:%d",
control,
tid,
expected_tid,
len(data) - 2,
)
if not (control & 0x80):
raise ValueError("Expected continuation flag but isn't set")
if tid != expected_tid:
raise ValueError(
f"Expected transaction {expected_tid} but got transaction {tid}"
)
return data[2:]
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