189 lines
6.6 KiB
Python
189 lines
6.6 KiB
Python
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"""
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wsproto/connection
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~~~~~~~~~~~~~~~~~~
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An implementation of a WebSocket connection.
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"""
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from collections import deque
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from enum import Enum
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from typing import Deque, Generator, List, Optional
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from .events import (
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BytesMessage,
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CloseConnection,
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Event,
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Message,
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Ping,
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Pong,
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TextMessage,
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)
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from .extensions import Extension
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from .frame_protocol import CloseReason, FrameProtocol, Opcode, ParseFailed
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from .utilities import LocalProtocolError
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class ConnectionState(Enum):
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"""
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RFC 6455, Section 4 - Opening Handshake
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"""
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#: The opening handshake is in progress.
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CONNECTING = 0
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#: The opening handshake is complete.
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OPEN = 1
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#: The remote WebSocket has initiated a connection close.
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REMOTE_CLOSING = 2
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#: The local WebSocket (i.e. this instance) has initiated a connection close.
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LOCAL_CLOSING = 3
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#: The closing handshake has completed.
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CLOSED = 4
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#: The connection was rejected during the opening handshake.
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REJECTING = 5
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class ConnectionType(Enum):
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""" An enumeration of connection types. """
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#: This connection will act as client and talk to a remote server
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CLIENT = 1
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#: This connection will as as server and waits for client connections
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SERVER = 2
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CLIENT = ConnectionType.CLIENT
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SERVER = ConnectionType.SERVER
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class Connection:
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"""
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A low-level WebSocket connection object.
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This wraps two other protocol objects, an HTTP/1.1 protocol object used
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to do the initial HTTP upgrade handshake and a WebSocket frame protocol
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object used to exchange messages and other control frames.
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:param conn_type: Whether this object is on the client- or server-side of
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a connection. To initialise as a client pass ``CLIENT`` otherwise
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pass ``SERVER``.
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:type conn_type: ``ConnectionType``
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"""
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def __init__(
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self,
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connection_type: ConnectionType,
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extensions: Optional[List[Extension]] = None,
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trailing_data: bytes = b"",
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) -> None:
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self.client = connection_type is ConnectionType.CLIENT
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self._events: Deque[Event] = deque()
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self._proto = FrameProtocol(self.client, extensions or [])
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self._state = ConnectionState.OPEN
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self.receive_data(trailing_data)
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@property
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def state(self) -> ConnectionState:
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return self._state
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def send(self, event: Event) -> bytes:
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data = b""
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if isinstance(event, Message):
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data += self._proto.send_data(event.data, event.message_finished)
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elif isinstance(event, Ping):
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data += self._proto.ping(event.payload)
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elif isinstance(event, Pong):
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data += self._proto.pong(event.payload)
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elif isinstance(event, CloseConnection):
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if self.state not in {ConnectionState.OPEN, ConnectionState.REMOTE_CLOSING}:
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raise LocalProtocolError(
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"Connection cannot be closed in state %s" % self.state
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)
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data += self._proto.close(event.code, event.reason)
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if self.state == ConnectionState.REMOTE_CLOSING:
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self._state = ConnectionState.CLOSED
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else:
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self._state = ConnectionState.LOCAL_CLOSING
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else:
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raise LocalProtocolError(f"Event {event} cannot be sent.")
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return data
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def receive_data(self, data: Optional[bytes]) -> None:
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"""
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Pass some received data to the connection for handling.
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A list of events that the remote peer triggered by sending this data can
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be retrieved with :meth:`~wsproto.connection.Connection.events`.
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:param data: The data received from the remote peer on the network.
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:type data: ``bytes``
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"""
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if data is None:
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# "If _The WebSocket Connection is Closed_ and no Close control
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# frame was received by the endpoint (such as could occur if the
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# underlying transport connection is lost), _The WebSocket
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# Connection Close Code_ is considered to be 1006."
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self._events.append(CloseConnection(code=CloseReason.ABNORMAL_CLOSURE))
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self._state = ConnectionState.CLOSED
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return
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if self.state in (ConnectionState.OPEN, ConnectionState.LOCAL_CLOSING):
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self._proto.receive_bytes(data)
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elif self.state is ConnectionState.CLOSED:
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raise LocalProtocolError("Connection already closed.")
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else:
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pass # pragma: no cover
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def events(self) -> Generator[Event, None, None]:
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"""
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Return a generator that provides any events that have been generated
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by protocol activity.
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:returns: generator of :class:`Event <wsproto.events.Event>` subclasses
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"""
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while self._events:
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yield self._events.popleft()
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try:
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for frame in self._proto.received_frames():
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if frame.opcode is Opcode.PING:
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assert frame.frame_finished and frame.message_finished
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assert isinstance(frame.payload, (bytes, bytearray))
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yield Ping(payload=frame.payload)
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elif frame.opcode is Opcode.PONG:
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assert frame.frame_finished and frame.message_finished
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assert isinstance(frame.payload, (bytes, bytearray))
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yield Pong(payload=frame.payload)
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elif frame.opcode is Opcode.CLOSE:
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assert isinstance(frame.payload, tuple)
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code, reason = frame.payload
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if self.state is ConnectionState.LOCAL_CLOSING:
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self._state = ConnectionState.CLOSED
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else:
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self._state = ConnectionState.REMOTE_CLOSING
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yield CloseConnection(code=code, reason=reason)
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elif frame.opcode is Opcode.TEXT:
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assert isinstance(frame.payload, str)
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yield TextMessage(
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data=frame.payload,
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frame_finished=frame.frame_finished,
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message_finished=frame.message_finished,
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)
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elif frame.opcode is Opcode.BINARY:
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assert isinstance(frame.payload, (bytes, bytearray))
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yield BytesMessage(
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data=frame.payload,
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frame_finished=frame.frame_finished,
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message_finished=frame.message_finished,
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)
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else:
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pass # pragma: no cover
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except ParseFailed as exc:
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yield CloseConnection(code=exc.code, reason=str(exc))
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