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# Copyright Pincer 2021-Present |
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# Full MIT License can be found in `LICENSE` at the project root. |
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from __future__ import annotations |
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from asyncio import create_task, Task, ensure_future, sleep |
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from dataclasses import dataclass |
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from datetime import datetime |
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from itertools import repeat, count, chain |
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import logging |
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from platform import system |
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from random import random |
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from typing import TYPE_CHECKING, Any, Dict, Callable, Optional |
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from zlib import decompressobj |
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from aiohttp import ( |
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ClientSession, WSMsgType, ClientConnectorError, ClientWebSocketResponse |
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) |
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from . import __package__ |
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from ..utils.api_object import APIObject |
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from .._config import GatewayConfig |
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from ..core.dispatch import GatewayDispatch |
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from ..exceptions import ( |
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InvalidTokenError, ConnectionError, GatewayError, UnhandledException |
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) |
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if TYPE_CHECKING: |
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from ..objects.app.intents import Intents |
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Handler = Callable[[GatewayDispatch], None] |
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_log = logging.getLogger(__package__) |
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ZLIB_SUFFIX = b'\x00\x00\xff\xff' |
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inflator = decompressobj() |
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@dataclass |
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class SessionStartLimit(APIObject): |
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"""Session start limit info returned from the `gateway/bot` endpoint""" |
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total: int |
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remaining: int |
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reset_after: int |
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max_concurrency: int |
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@dataclass |
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class GatewayInfo(APIObject): |
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"""Gateway info returned from the `gateway/bot` endpoint""" |
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url: str |
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shards: int |
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session_start_limit: SessionStartLimit |
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class Gateway: |
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"""The Gateway handles all interactions with the Discord Websocket API. |
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This also contains the main event loop, and handles the heartbeat. |
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Running the Gateway will create a connection with the |
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Discord Websocket API on behalf of the provided token. |
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This token must be a bot token. |
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(Which can be found on |
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`<https://discord.com/developers/applications/>`_) |
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""" |
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def __init__( |
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self, |
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token: str, *, |
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intents: Intents, |
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url: str, |
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shard: int, |
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num_shards: int |
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) -> None: |
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if len(token) != 59: |
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raise InvalidTokenError( |
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"Discord Token must have exactly 59 characters." |
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) |
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self.token = token |
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self.intents = intents |
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self.url = url |
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self.shard = shard |
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self.num_shards = num_shards |
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self.shard_key = [shard, num_shards] |
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self.__dispatch_handlers: Dict[int, Handler] = { |
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1: self.handle_heartbeat_req, |
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7: self.handle_reconnect, |
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9: self.handle_invalid_session, |
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10: self.identify_and_handle_hello, |
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11: self.handle_heartbeat |
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} |
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# 4000 and 4009 are not included. The client will reconnect when receiving |
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# either. |
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self.__close_codes: Dict[int, GatewayError] = { |
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4001: GatewayError("Invalid opcode was sent"), |
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4002: GatewayError("Invalid payload was sent."), |
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4003: GatewayError("Payload was sent prior to identifying"), |
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4004: GatewayError("Token is not valid"), |
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4005: GatewayError( |
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"Authentication was sent after client already authenticated" |
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), |
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4007: GatewayError("Invalid sequence sent when starting new session"), |
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4008: GatewayError("Client was rate limited"), |
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4010: GatewayError("Invalid shard"), |
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4011: GatewayError("Sharding required"), |
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4012: GatewayError("Invalid API version"), |
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4013: GatewayError("Invalid intents"), |
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4014: GatewayError("Disallowed intents") |
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} |
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# ClientSession to be used for this Dispatcher |
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self.__session: Optional[ClientSession] = None |
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# This type `_WSRequestContextManager` isn't exposed by aiohttp. |
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# `ClientWebSocketResponse` is a parent class. |
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self.__socket: Optional[ClientWebSocketResponse] = None |
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# Buffer used to store information in transport conpression. |
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self.__buffer = bytearray() |
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# The gateway can be disconnected from Discord. This variable stores if the |
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# gateway should send a hello or reconnect. |
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self.__should_reconnect: bool = False |
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# The sequence number for the last received payload. This is used reconnecting. |
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self.__sequence_number: int = 0 |
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# The heartbeat task |
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self.__heartbeat_task: Optional[Task] = None |
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# Keeps the Client waiting until the next heartbeat |
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self.__wait_for_heartbeat: Optional[Task] = None |
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# How long the client should wait between each Heartbeat. |
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self.__heartbeat_interval: Optional[int] = None |
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# Tracks whether the gateway has received an ack (opcode 11) since the last |
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# heartbeat. |
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# True: An ack has been received |
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# False: No ack has been received. Attempt to reconnect with gateway, |
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self.__has_received_ack: bool = True |
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# Session ID received from `on_ready` event. It is set in the `on_ready` |
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# middleware. This is used reconnecting. |
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self.__session_id: Optional[str] = None |
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def __del__(self): |
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"""Delete method ensures all connections are closed""" |
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if self.__socket: |
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create_task(self.__socket.close()) |
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if self.__session: |
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create_task(self.__session.close()) |
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async def init_session(self): |
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""" |
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Crates the ClientSession. ALWAYS run this function right after initializing |
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a Gateway. |
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""" |
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self.__session = ClientSession() |
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def append_handlers(self, handlers: Dict[int, Handler]): |
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"""The Client that uses the handler can append their own methods. The gateway |
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will run those methods when the specified opcode is received. |
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""" |
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self.__dispatch_handlers = handlers | self.__dispatch_handlers |
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def set_session_id(self, _id: str): |
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"""Session id is private for consistency""" |
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self.__session_id = _id |
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def decompress_msg(self, msg: bytes) -> Optional[str]: |
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if GatewayConfig.compression == "zlib-payload": |
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return inflator.decompress(msg) |
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if GatewayConfig.compression == "zlib-stream": |
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self.__buffer.extend(msg) |
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if len(self.__buffer) < 4 or self.__buffer[-4:] != ZLIB_SUFFIX: |
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return None |
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msg = inflator.decompress(msg) |
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self.__buffer = bytearray() |
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return msg |
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return None |
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async def start_loop(self): |
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"""Instantiate the dispatcher, this will create a connection to the |
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Discord websocket API on behalf of the client whose token has |
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been passed. |
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""" |
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for i in count(): |
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try: |
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self.__socket = await self.__session.ws_connect( |
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GatewayConfig.make_uri(self.url) |
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) |
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break |
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except ClientConnectorError as e: |
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if i > GatewayConfig.MAX_RETRIES: |
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raise ConnectionError from e |
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_log.warning( |
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"%s Could not open websocket with Discord." |
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" Retrying in 15 seconds...", |
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self.shard_key |
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) |
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await sleep(15) |
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_log.debug("%s Starting envent loop...", self.shard_key) |
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await self.event_loop() |
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async def event_loop(self): |
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"""Handles receiving messages and decompressing them if needed""" |
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async for msg in self.__socket: |
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if msg.type == WSMsgType.TEXT: |
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await self.handle_data(msg.data) |
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elif msg.type == WSMsgType.BINARY: |
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# Message from transport compression that isn't complete returns None |
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data = self.decompress_msg(msg.data) |
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if data: |
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await self.handle_data(data) |
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elif msg.type == WSMsgType.ERROR: |
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raise GatewayError from self.__socket.exception() |
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# The loop is broken when the gateway stops receiving messages. |
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# The "error" op codes are in `self.__close_codes`. The rest of the |
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# close codes are unknown issues (such as a unintended disconnect) so the |
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# client should reconnect to the gateway. |
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err = self.__close_codes.get(self.__socket.close_code) |
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if err: |
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raise err |
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_log.debug( |
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"%s Disconnected from Gateway due without any errors. Reconnecting.", |
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self.shard_key |
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) |
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self.__should_reconnect = True |
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self.start_loop() |
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async def handle_data(self, data: Dict[Any]): |
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"""Method is run when a payload is received from the gateway. |
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The message is expected to already have been decompressed. |
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Handling the opcode is forked to the background so they aren't blocking. |
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""" |
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payload = GatewayDispatch.from_string(data) |
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# Op code -1 is activated on all payloads |
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op_negative_one = self.__dispatch_handlers.get(-1) |
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if op_negative_one: |
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ensure_future(op_negative_one(payload)) |
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_log.debug( |
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"%s %s GatewayDispatch with opcode %s received", |
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self.shard_key, |
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datetime.now(), |
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payload.op |
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) |
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# Many events are sent with a `null` sequence. This sequence should not |
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# be tracked. |
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if payload.seq is not None: |
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self.__sequence_number = payload.seq |
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_log.debug("%s Set sequence number to %s", self.shard_key, payload.seq) |
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handler = self.__dispatch_handlers.get(payload.op) |
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if handler is None: |
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raise UnhandledException(f"Opcode {payload.op} does not have a handler") |
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ensure_future(handler(payload)) |
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async def handle_heartbeat_req(self, payload: GatewayDispatch): |
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""" |
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Opcode 1 - Instantly send a heartbeat. |
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""" |
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self.send_next_heartbeat() |
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async def handle_reconnect(self, payload: GatewayDispatch): |
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""" |
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Opcode 7 - Reconnect and resume immediately. |
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""" |
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_log.debug( |
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"%s Requested to reconnect to Discord. Closing session and attempting to" |
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" resume...", |
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self.shard_key |
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) |
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await self.__socket.close(code=1000) |
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self.__should_reconnect = True |
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await self.start_loop() |
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async def handle_invalid_session(self, payload: GatewayDispatch): |
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""" |
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Opcode 9 - Invalid connection |
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Attempt to relog. This is probably because the session was already invalidated |
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when we tried to reconnect. |
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""" |
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_log.debug("%s Invalid session, attempting to relog...", self.shard_key) |
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self.__should_reconnect = False |
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await self.start_loop() |
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async def identify_and_handle_hello(self, payload: GatewayDispatch): |
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""" |
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Opcode 10 - Hello there general kenobi |
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Runs when we connect to the gateway for the first time and every time after. |
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If the client thinks it should reconnect, the opcode 6 resume payload is sent |
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instead of the opcode 2 hello payload. A new session is only started after a |
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reconnect if pcode 9 is received. |
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Successful reconnects are handled in the `resumed` middleware. |
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""" |
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if self.__should_reconnect: |
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_log.debug("%s Resuming connection with Discord", self.shard_key) |
|
319
|
|
|
|
|
320
|
|
|
await self.send(str(GatewayDispatch( |
|
321
|
|
|
6, { |
|
322
|
|
|
"token": self.token, |
|
323
|
|
|
"session_id": self.__session_id, |
|
324
|
|
|
"seq": self.__sequence_number |
|
325
|
|
|
} |
|
326
|
|
|
))) |
|
327
|
|
|
return |
|
328
|
|
|
|
|
329
|
|
|
await self.send(str( |
|
330
|
|
|
GatewayDispatch( |
|
331
|
|
|
2, { |
|
332
|
|
|
"token": self.token, |
|
333
|
|
|
"intents": self.intents, |
|
334
|
|
|
"properties": { |
|
335
|
|
|
"$os": system(), |
|
336
|
|
|
"$browser": __package__, |
|
337
|
|
|
"$device": __package__ |
|
338
|
|
|
}, |
|
339
|
|
|
"compress": GatewayConfig.compressed(), |
|
340
|
|
|
"shard": self.shard_key |
|
341
|
|
|
} |
|
342
|
|
|
) |
|
343
|
|
|
)) |
|
344
|
|
|
self.__heartbeat_interval = payload.data["heartbeat_interval"] |
|
345
|
|
|
|
|
346
|
|
|
# This process should already be forked to the background so there is no need to |
|
347
|
|
|
# `ensure_future()` here. |
|
348
|
|
|
self.start_heartbeat() |
|
349
|
|
|
|
|
350
|
|
|
async def handle_heartbeat(self, payload: GatewayDispatch): |
|
|
|
|
|
|
351
|
|
|
""" |
|
352
|
|
|
Opcode 11 - Heatbeat |
|
353
|
|
|
Track that the heartbeat has been received using shared state (Rustaceans would |
|
354
|
|
|
be very mad) |
|
355
|
|
|
""" |
|
356
|
|
|
self.__has_received_ack = True |
|
357
|
|
|
|
|
358
|
|
|
async def send(self, payload: str): |
|
359
|
|
|
""" |
|
360
|
|
|
Send a string object to the payload. Most of this method is just logging, |
|
361
|
|
|
the last line is the only one that matters for functionality. |
|
362
|
|
|
""" |
|
363
|
|
|
safe_payload = payload.replace(self.token, "%s..." % self.token[:10]) |
|
364
|
|
|
|
|
365
|
|
|
if self.__session_id: |
|
366
|
|
|
safe_payload = safe_payload.replace( |
|
367
|
|
|
self.__session_id, "%s..." % self.__session_id[:4] |
|
368
|
|
|
) |
|
369
|
|
|
|
|
370
|
|
|
_log.debug( |
|
371
|
|
|
"%s Sending payload: %s", |
|
372
|
|
|
self.shard_key, |
|
373
|
|
|
safe_payload |
|
374
|
|
|
) |
|
375
|
|
|
|
|
376
|
|
|
if self.__socket.closed: |
|
377
|
|
|
_log.debug( |
|
378
|
|
|
"%s Socket is closing. Payload not sent.", |
|
379
|
|
|
self.shard_key |
|
380
|
|
|
) |
|
381
|
|
|
return |
|
382
|
|
|
|
|
383
|
|
|
await self.__socket.send_str(payload) |
|
384
|
|
|
|
|
385
|
|
|
def start_heartbeat(self): |
|
386
|
|
|
""" |
|
387
|
|
|
Starts the heartbeat if it is not already running. |
|
388
|
|
|
""" |
|
389
|
|
|
if not self.__heartbeat_task or self.__heartbeat_task.cancelled(): |
|
390
|
|
|
self.__heartbeat_task = ensure_future(self.__heartbeat_loop()) |
|
391
|
|
|
|
|
392
|
|
|
def stop_heartbeat(self): |
|
|
|
|
|
|
393
|
|
|
self.__heartbeat_task.cancel() |
|
394
|
|
|
|
|
395
|
|
|
def send_next_heartbeat(self): |
|
396
|
|
|
""" |
|
397
|
|
|
It is expected to always be waiting for a hearbeat. By canceling that task, |
|
398
|
|
|
a heartbeat can be sent. |
|
399
|
|
|
""" |
|
400
|
|
|
self.__wait_for_heartbeat.cancel() |
|
401
|
|
|
|
|
402
|
|
|
async def __heartbeat_loop(self): |
|
403
|
|
|
""" |
|
404
|
|
|
The heartbeat is responsible for keeping the connection to Discord alive. |
|
405
|
|
|
|
|
406
|
|
|
Jitter is only random for the first heartbeat. It should be 1 every other |
|
407
|
|
|
heartbeat. |
|
408
|
|
|
""" |
|
409
|
|
|
_log.debug("%s Starting heartbeat loop...", self.shard_key) |
|
410
|
|
|
|
|
411
|
|
|
# When waiting for first heartbeat, there hasn't been an ack received yet. |
|
412
|
|
|
# Set to true so the ack received check doesn't incorrectly fail. |
|
413
|
|
|
self.__has_received_ack = True |
|
414
|
|
|
|
|
415
|
|
|
for jitter in chain((random(),), repeat(1)): |
|
416
|
|
|
duration = self.__heartbeat_interval * jitter |
|
417
|
|
|
|
|
418
|
|
|
_log.debug( |
|
419
|
|
|
"%s %s sending heartbeat in %sms", |
|
420
|
|
|
self.shard_key, datetime.now(), |
|
421
|
|
|
duration |
|
422
|
|
|
) |
|
423
|
|
|
|
|
424
|
|
|
# Task is needed so waiting can be cancelled by op code 1 |
|
425
|
|
|
self.__wait_for_heartbeat = create_task( |
|
426
|
|
|
sleep(duration / 1000) |
|
427
|
|
|
) |
|
428
|
|
|
|
|
429
|
|
|
await self.__wait_for_heartbeat |
|
430
|
|
|
|
|
431
|
|
|
if not self.__has_received_ack: |
|
432
|
|
|
# Close code is specified to be anything that is not 1000 in the docs. |
|
433
|
|
|
_log.debug( |
|
434
|
|
|
"%s %s ack not received. Attempting to reconnect." |
|
435
|
|
|
" Closing socket with close code 1001. \U0001f480", |
|
436
|
|
|
datetime.now(), |
|
437
|
|
|
self.shard_key |
|
438
|
|
|
) |
|
439
|
|
|
await self.__socket.close(code=1001) |
|
440
|
|
|
self.__should_reconnect = True |
|
441
|
|
|
# A new loop is started in the background while this one is stopped. |
|
442
|
|
|
ensure_future(self.start_loop()) |
|
443
|
|
|
self.stop_heartbeat() |
|
444
|
|
|
return |
|
445
|
|
|
|
|
446
|
|
|
self.__has_received_ack = False |
|
447
|
|
|
await self.send(str(GatewayDispatch(1, data=self.__sequence_number))) |
|
448
|
|
|
_log.debug("%s sent heartbeat", self.shard_key) |
|
449
|
|
|
|