mirror of
https://github.com/python-kasa/python-kasa.git
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528f5e9e07
The code should always be called from the same thread that created the object or we have a thread safety problem.
225 lines
8.4 KiB
Python
Executable File
225 lines
8.4 KiB
Python
Executable File
"""Implementation of the TP-Link Smart Home Protocol.
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Encryption/Decryption methods based on the works of
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Lubomir Stroetmann and Tobias Esser
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https://www.softscheck.com/en/reverse-engineering-tp-link-hs110/
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https://github.com/softScheck/tplink-smartplug/
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which are licensed under the Apache License, Version 2.0
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http://www.apache.org/licenses/LICENSE-2.0
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"""
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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 struct
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from pprint import pformat as pf
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from typing import Dict, Generator, Optional, Union
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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 .exceptions import SmartDeviceException
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from .json import dumps as json_dumps
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from .json import loads as json_loads
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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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class TPLinkSmartHomeProtocol:
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"""Implementation of the TP-Link Smart Home protocol."""
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INITIALIZATION_VECTOR = 171
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DEFAULT_PORT = 9999
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DEFAULT_TIMEOUT = 5
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BLOCK_SIZE = 4
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def __init__(
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self, host: str, *, port: Optional[int] = None, timeout: Optional[int] = None
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) -> None:
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"""Create a protocol object."""
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self.host = host
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self.port = port or TPLinkSmartHomeProtocol.DEFAULT_PORT
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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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self.timeout = timeout or TPLinkSmartHomeProtocol.DEFAULT_TIMEOUT
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async def query(self, request: Union[str, Dict], retry_count: int = 3) -> Dict:
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"""Request information from a TP-Link SmartHome Device.
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:param str host: host name or ip address of the device
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:param request: command to send to the device (can be either dict or
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json string)
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:param retry_count: how many retries to do in case of failure
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:return: response dict
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"""
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if isinstance(request, dict):
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request = json_dumps(request)
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assert isinstance(request, str)
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async with self.query_lock:
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return await self._query(request, retry_count, self.timeout)
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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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async def _execute_query(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
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assert self.reader is not None
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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(TPLinkSmartHomeProtocol.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 = struct.unpack(">I", packed_block_size)[0]
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buffer = await self.reader.readexactly(length)
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response = TPLinkSmartHomeProtocol.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.reader = self.writer = None
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if writer:
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writer.close()
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with contextlib.suppress(Exception):
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await writer.wait_closed()
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def _reset(self) -> None:
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"""Clear any varibles that should not survive between loops."""
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self.reader = self.writer = None
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async def _query(self, request: str, retry_count: int, timeout: int) -> Dict:
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"""Try to query a device."""
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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 ConnectionRefusedError)
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# we do not want to keep trying since many connection open/close operations
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# in the same time frame can block the event loop. This is especially
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# import when there are multiple tplink devices being polled.
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#
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for retry in range(retry_count + 1):
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try:
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await self._connect(timeout)
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except ConnectionRefusedError as ex:
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await self.close()
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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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)
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except OSError as ex:
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await self.close()
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if ex.errno in _NO_RETRY_ERRORS or retry >= retry_count:
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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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)
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continue
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except Exception as ex:
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await self.close()
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if retry >= retry_count:
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_LOGGER.debug("Giving up on %s after %s retries", self.host, retry)
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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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)
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continue
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try:
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assert self.reader is not None
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assert self.writer is not None
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async with asyncio_timeout(timeout):
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return await self._execute_query(request)
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except Exception as ex:
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await self.close()
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if retry >= retry_count:
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_LOGGER.debug("Giving up on %s after %s retries", self.host, retry)
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raise SmartDeviceException(
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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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_LOGGER.debug(
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"Unable to query the device %s, retrying: %s", self.host, ex
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)
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# make mypy happy, this should never be reached..
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await self.close()
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raise SmartDeviceException("Query reached somehow to unreachable")
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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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self._reset()
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@staticmethod
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def _xor_payload(unencrypted: bytes) -> Generator[int, None, None]:
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key = TPLinkSmartHomeProtocol.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 struct.pack(">I", len(plainbytes)) + bytes(
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TPLinkSmartHomeProtocol._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 = TPLinkSmartHomeProtocol.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(
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TPLinkSmartHomeProtocol._xor_encrypted_payload(ciphertext)
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).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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TPLinkSmartHomeProtocol.decrypt = decrypt # type: ignore[method-assign]
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TPLinkSmartHomeProtocol.encrypt = encrypt # type: ignore[method-assign]
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except ImportError:
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pass
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