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https://github.com/python-kasa/python-kasa.git
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229 lines
8.3 KiB
Python
229 lines
8.3 KiB
Python
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"""Module for the XorTransport."""
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import asyncio
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import contextlib
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import errno
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import logging
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import socket
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import struct
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from pprint import pformat as pf
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from typing import Dict, Generator, Optional
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# When support for cpython older than 3.11 is dropped
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# async_timeout can be replaced with asyncio.timeout
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from async_timeout import timeout as asyncio_timeout
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from .deviceconfig import DeviceConfig
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from .exceptions import RetryableException, SmartDeviceException
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from .json import loads as json_loads
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from .protocol import BaseTransport
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_LOGGER = logging.getLogger(__name__)
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_NO_RETRY_ERRORS = {errno.EHOSTDOWN, errno.EHOSTUNREACH, errno.ECONNREFUSED}
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_UNSIGNED_INT_NETWORK_ORDER = struct.Struct(">I")
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class XorTransport(BaseTransport):
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"""Implementation of the Xor encryption transport.
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WIP, currently only to ensure consistent __init__ method signatures
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for protocol classes. Will eventually incorporate the logic from
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TPLinkSmartHomeProtocol to simplify the API and re-use the IotProtocol
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class.
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"""
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DEFAULT_PORT: int = 9999
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BLOCK_SIZE = 4
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def __init__(self, *, config: DeviceConfig) -> None:
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super().__init__(config=config)
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self.reader: Optional[asyncio.StreamReader] = None
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self.writer: Optional[asyncio.StreamWriter] = None
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self.query_lock = asyncio.Lock()
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self.loop: Optional[asyncio.AbstractEventLoop] = None
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@property
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def default_port(self):
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"""Default port for the transport."""
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return self.DEFAULT_PORT
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@property
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def credentials_hash(self) -> str:
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"""The hashed credentials used by the transport."""
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return ""
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async def _connect(self, timeout: int) -> None:
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"""Try to connect or reconnect to the device."""
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if self.writer:
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return
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self.reader = self.writer = None
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task = asyncio.open_connection(self._host, self._port)
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async with asyncio_timeout(timeout):
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self.reader, self.writer = await task
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sock: socket.socket = self.writer.get_extra_info("socket")
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# Ensure our packets get sent without delay as we do all
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# our writes in a single go and we do not want any buffering
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# which would needlessly delay the request or risk overloading
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# the buffer on the device
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sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
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async def _execute_send(self, request: str) -> Dict:
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"""Execute a query on the device and wait for the response."""
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assert self.writer is not None # noqa: S101
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assert self.reader is not None # noqa: S101
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debug_log = _LOGGER.isEnabledFor(logging.DEBUG)
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if debug_log:
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_LOGGER.debug("%s >> %s", self._host, request)
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self.writer.write(XorEncryption.encrypt(request))
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await self.writer.drain()
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packed_block_size = await self.reader.readexactly(self.BLOCK_SIZE)
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length = _UNSIGNED_INT_NETWORK_ORDER.unpack(packed_block_size)[0]
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buffer = await self.reader.readexactly(length)
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response = XorEncryption.decrypt(buffer)
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json_payload = json_loads(response)
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if debug_log:
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_LOGGER.debug("%s << %s", self._host, pf(json_payload))
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return json_payload
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async def close(self) -> None:
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"""Close the connection."""
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writer = self.writer
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self.close_without_wait()
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if writer:
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with contextlib.suppress(Exception):
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await writer.wait_closed()
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def close_without_wait(self) -> None:
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"""Close the connection without waiting for the connection to close."""
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writer = self.writer
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self.reader = self.writer = None
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if writer:
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writer.close()
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async def reset(self) -> None:
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"""Reset the transport.
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The transport cannot be reset so we must close instead.
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"""
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await self.close()
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async def send(self, request: str) -> Dict:
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"""Send a message to the device and return a response."""
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#
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# Most of the time we will already be connected if the device is online
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# and the connect call will do nothing and return right away
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#
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# However, if we get an unrecoverable error (_NO_RETRY_ERRORS and
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# ConnectionRefusedError) we do not want to keep trying since many
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# connection open/close operations in the same time frame can block
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# the event loop.
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# This is especially import when there are multiple tplink devices being polled.
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try:
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await self._connect(self._timeout)
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except ConnectionRefusedError as ex:
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await self.reset()
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raise SmartDeviceException(
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f"Unable to connect to the device: {self._host}:{self._port}: {ex}"
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) from ex
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except OSError as ex:
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await self.reset()
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if ex.errno in _NO_RETRY_ERRORS:
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raise SmartDeviceException(
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f"Unable to connect to the device:"
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f" {self._host}:{self._port}: {ex}"
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) from ex
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else:
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raise RetryableException(
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f"Unable to connect to the device:"
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f" {self._host}:{self._port}: {ex}"
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) from ex
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except Exception as ex:
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await self.reset()
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raise RetryableException(
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f"Unable to connect to the device:" f" {self._host}:{self._port}: {ex}"
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) from ex
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except BaseException:
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# Likely something cancelled the task so we need to close the connection
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# as we are not in an indeterminate state
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self.close_without_wait()
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raise
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try:
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assert self.reader is not None # noqa: S101
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assert self.writer is not None # noqa: S101
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async with asyncio_timeout(self._timeout):
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return await self._execute_send(request)
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except Exception as ex:
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await self.reset()
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raise RetryableException(
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f"Unable to query the device {self._host}:{self._port}: {ex}"
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) from ex
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except BaseException:
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# Likely something cancelled the task so we need to close the connection
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# as we are not in an indeterminate state
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self.close_without_wait()
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raise
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def __del__(self) -> None:
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if self.writer and self.loop and self.loop.is_running():
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# Since __del__ will be called when python does
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# garbage collection is can happen in the event loop thread
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# or in another thread so we need to make sure the call to
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# close is called safely with call_soon_threadsafe
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self.loop.call_soon_threadsafe(self.writer.close)
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class XorEncryption:
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"""XorEncryption class."""
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INITIALIZATION_VECTOR = 171
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@staticmethod
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def _xor_payload(unencrypted: bytes) -> Generator[int, None, None]:
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key = XorEncryption.INITIALIZATION_VECTOR
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for unencryptedbyte in unencrypted:
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key = key ^ unencryptedbyte
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yield key
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@staticmethod
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def encrypt(request: str) -> bytes:
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"""Encrypt a request for a TP-Link Smart Home Device.
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:param request: plaintext request data
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:return: ciphertext to be send over wire, in bytes
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"""
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plainbytes = request.encode()
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return _UNSIGNED_INT_NETWORK_ORDER.pack(len(plainbytes)) + bytes(
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XorEncryption._xor_payload(plainbytes)
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)
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@staticmethod
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def _xor_encrypted_payload(ciphertext: bytes) -> Generator[int, None, None]:
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key = XorEncryption.INITIALIZATION_VECTOR
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for cipherbyte in ciphertext:
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plainbyte = key ^ cipherbyte
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key = cipherbyte
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yield plainbyte
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@staticmethod
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def decrypt(ciphertext: bytes) -> str:
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"""Decrypt a response of a TP-Link Smart Home Device.
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:param ciphertext: encrypted response data
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:return: plaintext response
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"""
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return bytes(XorEncryption._xor_encrypted_payload(ciphertext)).decode()
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# Try to load the kasa_crypt module and if it is available
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try:
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from kasa_crypt import decrypt, encrypt
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XorEncryption.decrypt = decrypt # type: ignore[method-assign]
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XorEncryption.encrypt = encrypt # type: ignore[method-assign]
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except ImportError:
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pass
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