from __future__ import annotations import asyncio import collections import contextlib import logging import random import struct import sys import traceback import uuid from collections.abc import AsyncIterable, AsyncIterator, Awaitable, Iterable, Mapping from types import TracebackType from typing import Any, Literal, cast, overload from ..exceptions import ( ConcurrencyError, ConnectionClosed, ConnectionClosedOK, ProtocolError, ) from ..frames import DATA_OPCODES, BytesLike, CloseCode, Frame, Opcode from ..http11 import Request, Response from ..protocol import CLOSED, OPEN, Event, Protocol, State from ..typing import Data, LoggerLike, Subprotocol from .compatibility import ( TimeoutError, aiter, anext, asyncio_timeout, asyncio_timeout_at, ) from .messages import Assembler __all__ = ["Connection"] class Connection(asyncio.Protocol): """ :mod:`asyncio` implementation of a WebSocket connection. :class:`Connection` provides APIs shared between WebSocket servers and clients. You shouldn't use it directly. Instead, use :class:`~websockets.asyncio.client.ClientConnection` or :class:`~websockets.asyncio.server.ServerConnection`. """ def __init__( self, protocol: Protocol, *, ping_interval: float | None = 20, ping_timeout: float | None = 20, close_timeout: float | None = 10, max_queue: int | None | tuple[int | None, int | None] = 16, write_limit: int | tuple[int, int | None] = 2**15, ) -> None: self.protocol = protocol self.ping_interval = ping_interval self.ping_timeout = ping_timeout self.close_timeout = close_timeout if isinstance(max_queue, int) or max_queue is None: max_queue = (max_queue, None) self.max_queue = max_queue if isinstance(write_limit, int): write_limit = (write_limit, None) self.write_limit = write_limit # Inject reference to this instance in the protocol's logger. self.protocol.logger = logging.LoggerAdapter( self.protocol.logger, {"websocket": self}, ) # Copy attributes from the protocol for convenience. self.id: uuid.UUID = self.protocol.id """Unique identifier of the connection. Useful in logs.""" self.logger: LoggerLike = self.protocol.logger """Logger for this connection.""" self.debug = self.protocol.debug # HTTP handshake request and response. self.request: Request | None = None """Opening handshake request.""" self.response: Response | None = None """Opening handshake response.""" # Event loop running this connection. self.loop = asyncio.get_running_loop() # Assembler turning frames into messages and serializing reads. self.recv_messages: Assembler # initialized in connection_made # Deadline for the closing handshake. self.close_deadline: float | None = None # Protect sending fragmented messages. self.fragmented_send_waiter: asyncio.Future[None] | None = None # Mapping of ping IDs to pong waiters, in chronological order. self.pong_waiters: dict[bytes, tuple[asyncio.Future[float], float]] = {} self.latency: float = 0 """ Latency of the connection, in seconds. Latency is defined as the round-trip time of the connection. It is measured by sending a Ping frame and waiting for a matching Pong frame. Before the first measurement, :attr:`latency` is ``0``. By default, websockets enables a :ref:`keepalive ` mechanism that sends Ping frames automatically at regular intervals. You can also send Ping frames and measure latency with :meth:`ping`. """ # Task that sends keepalive pings. None when ping_interval is None. self.keepalive_task: asyncio.Task[None] | None = None # Exception raised while reading from the connection, to be chained to # ConnectionClosed in order to show why the TCP connection dropped. self.recv_exc: BaseException | None = None # Completed when the TCP connection is closed and the WebSocket # connection state becomes CLOSED. self.connection_lost_waiter: asyncio.Future[None] = self.loop.create_future() # Adapted from asyncio.FlowControlMixin self.paused: bool = False self.drain_waiters: collections.deque[asyncio.Future[None]] = ( collections.deque() ) # Public attributes @property def local_address(self) -> Any: """ Local address of the connection. For IPv4 connections, this is a ``(host, port)`` tuple. The format of the address depends on the address family. See :meth:`~socket.socket.getsockname`. """ return self.transport.get_extra_info("sockname") @property def remote_address(self) -> Any: """ Remote address of the connection. For IPv4 connections, this is a ``(host, port)`` tuple. The format of the address depends on the address family. See :meth:`~socket.socket.getpeername`. """ return self.transport.get_extra_info("peername") @property def state(self) -> State: """ State of the WebSocket connection, defined in :rfc:`6455`. This attribute is provided for completeness. Typical applications shouldn't check its value. Instead, they should call :meth:`~recv` or :meth:`send` and handle :exc:`~websockets.exceptions.ConnectionClosed` exceptions. """ return self.protocol.state @property def subprotocol(self) -> Subprotocol | None: """ Subprotocol negotiated during the opening handshake. :obj:`None` if no subprotocol was negotiated. """ return self.protocol.subprotocol @property def close_code(self) -> int | None: """ State of the WebSocket connection, defined in :rfc:`6455`. This attribute is provided for completeness. Typical applications shouldn't check its value. Instead, they should inspect attributes of :exc:`~websockets.exceptions.ConnectionClosed` exceptions. """ return self.protocol.close_code @property def close_reason(self) -> str | None: """ State of the WebSocket connection, defined in :rfc:`6455`. This attribute is provided for completeness. Typical applications shouldn't check its value. Instead, they should inspect attributes of :exc:`~websockets.exceptions.ConnectionClosed` exceptions. """ return self.protocol.close_reason # Public methods async def __aenter__(self) -> Connection: return self async def __aexit__( self, exc_type: type[BaseException] | None, exc_value: BaseException | None, traceback: TracebackType | None, ) -> None: if exc_type is None: await self.close() else: await self.close(CloseCode.INTERNAL_ERROR) async def __aiter__(self) -> AsyncIterator[Data]: """ Iterate on incoming messages. The iterator calls :meth:`recv` and yields messages asynchronously in an infinite loop. It exits when the connection is closed normally. It raises a :exc:`~websockets.exceptions.ConnectionClosedError` exception after a protocol error or a network failure. """ try: while True: yield await self.recv() except ConnectionClosedOK: return @overload async def recv(self, decode: Literal[True]) -> str: ... @overload async def recv(self, decode: Literal[False]) -> bytes: ... @overload async def recv(self, decode: bool | None = None) -> Data: ... async def recv(self, decode: bool | None = None) -> Data: """ Receive the next message. When the connection is closed, :meth:`recv` raises :exc:`~websockets.exceptions.ConnectionClosed`. Specifically, it raises :exc:`~websockets.exceptions.ConnectionClosedOK` after a normal closure and :exc:`~websockets.exceptions.ConnectionClosedError` after a protocol error or a network failure. This is how you detect the end of the message stream. Canceling :meth:`recv` is safe. There's no risk of losing data. The next invocation of :meth:`recv` will return the next message. This makes it possible to enforce a timeout by wrapping :meth:`recv` in :func:`~asyncio.timeout` or :func:`~asyncio.wait_for`. When the message is fragmented, :meth:`recv` waits until all fragments are received, reassembles them, and returns the whole message. Args: decode: Set this flag to override the default behavior of returning :class:`str` or :class:`bytes`. See below for details. Returns: A string (:class:`str`) for a Text_ frame or a bytestring (:class:`bytes`) for a Binary_ frame. .. _Text: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6 .. _Binary: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6 You may override this behavior with the ``decode`` argument: * Set ``decode=False`` to disable UTF-8 decoding of Text_ frames and return a bytestring (:class:`bytes`). This improves performance when decoding isn't needed, for example if the message contains JSON and you're using a JSON library that expects a bytestring. * Set ``decode=True`` to force UTF-8 decoding of Binary_ frames and return a string (:class:`str`). This may be useful for servers that send binary frames instead of text frames. Raises: ConnectionClosed: When the connection is closed. ConcurrencyError: If two coroutines call :meth:`recv` or :meth:`recv_streaming` concurrently. """ try: return await self.recv_messages.get(decode) except EOFError: pass # fallthrough except ConcurrencyError: raise ConcurrencyError( "cannot call recv while another coroutine " "is already running recv or recv_streaming" ) from None except UnicodeDecodeError as exc: async with self.send_context(): self.protocol.fail( CloseCode.INVALID_DATA, f"{exc.reason} at position {exc.start}", ) # fallthrough # Wait for the protocol state to be CLOSED before accessing close_exc. await asyncio.shield(self.connection_lost_waiter) raise self.protocol.close_exc from self.recv_exc @overload def recv_streaming(self, decode: Literal[True]) -> AsyncIterator[str]: ... @overload def recv_streaming(self, decode: Literal[False]) -> AsyncIterator[bytes]: ... @overload def recv_streaming(self, decode: bool | None = None) -> AsyncIterator[Data]: ... async def recv_streaming(self, decode: bool | None = None) -> AsyncIterator[Data]: """ Receive the next message frame by frame. This method is designed for receiving fragmented messages. It returns an asynchronous iterator that yields each fragment as it is received. This iterator must be fully consumed. Else, future calls to :meth:`recv` or :meth:`recv_streaming` will raise :exc:`~websockets.exceptions.ConcurrencyError`, making the connection unusable. :meth:`recv_streaming` raises the same exceptions as :meth:`recv`. Canceling :meth:`recv_streaming` before receiving the first frame is safe. Canceling it after receiving one or more frames leaves the iterator in a partially consumed state, making the connection unusable. Instead, you should close the connection with :meth:`close`. Args: decode: Set this flag to override the default behavior of returning :class:`str` or :class:`bytes`. See below for details. Returns: An iterator of strings (:class:`str`) for a Text_ frame or bytestrings (:class:`bytes`) for a Binary_ frame. .. _Text: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6 .. _Binary: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6 You may override this behavior with the ``decode`` argument: * Set ``decode=False`` to disable UTF-8 decoding of Text_ frames and return bytestrings (:class:`bytes`). This may be useful to optimize performance when decoding isn't needed. * Set ``decode=True`` to force UTF-8 decoding of Binary_ frames and return strings (:class:`str`). This is useful for servers that send binary frames instead of text frames. Raises: ConnectionClosed: When the connection is closed. ConcurrencyError: If two coroutines call :meth:`recv` or :meth:`recv_streaming` concurrently. """ try: async for frame in self.recv_messages.get_iter(decode): yield frame return except EOFError: pass # fallthrough except ConcurrencyError: raise ConcurrencyError( "cannot call recv_streaming while another coroutine " "is already running recv or recv_streaming" ) from None except UnicodeDecodeError as exc: async with self.send_context(): self.protocol.fail( CloseCode.INVALID_DATA, f"{exc.reason} at position {exc.start}", ) # fallthrough # Wait for the protocol state to be CLOSED before accessing close_exc. await asyncio.shield(self.connection_lost_waiter) raise self.protocol.close_exc from self.recv_exc async def send( self, message: Data | Iterable[Data] | AsyncIterable[Data], text: bool | None = None, ) -> None: """ Send a message. A string (:class:`str`) is sent as a Text_ frame. A bytestring or bytes-like object (:class:`bytes`, :class:`bytearray`, or :class:`memoryview`) is sent as a Binary_ frame. .. _Text: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6 .. _Binary: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6 You may override this behavior with the ``text`` argument: * Set ``text=True`` to send a bytestring or bytes-like object (:class:`bytes`, :class:`bytearray`, or :class:`memoryview`) as a Text_ frame. This improves performance when the message is already UTF-8 encoded, for example if the message contains JSON and you're using a JSON library that produces a bytestring. * Set ``text=False`` to send a string (:class:`str`) in a Binary_ frame. This may be useful for servers that expect binary frames instead of text frames. :meth:`send` also accepts an iterable or an asynchronous iterable of strings, bytestrings, or bytes-like objects to enable fragmentation_. Each item is treated as a message fragment and sent in its own frame. All items must be of the same type, or else :meth:`send` will raise a :exc:`TypeError` and the connection will be closed. .. _fragmentation: https://datatracker.ietf.org/doc/html/rfc6455#section-5.4 :meth:`send` rejects dict-like objects because this is often an error. (If you really want to send the keys of a dict-like object as fragments, call its :meth:`~dict.keys` method and pass the result to :meth:`send`.) Canceling :meth:`send` is discouraged. Instead, you should close the connection with :meth:`close`. Indeed, there are only two situations where :meth:`send` may yield control to the event loop and then get canceled; in both cases, :meth:`close` has the same effect and is more clear: 1. The write buffer is full. If you don't want to wait until enough data is sent, your only alternative is to close the connection. :meth:`close` will likely time out then abort the TCP connection. 2. ``message`` is an asynchronous iterator that yields control. Stopping in the middle of a fragmented message will cause a protocol error and the connection will be closed. When the connection is closed, :meth:`send` raises :exc:`~websockets.exceptions.ConnectionClosed`. Specifically, it raises :exc:`~websockets.exceptions.ConnectionClosedOK` after a normal connection closure and :exc:`~websockets.exceptions.ConnectionClosedError` after a protocol error or a network failure. Args: message: Message to send. Raises: ConnectionClosed: When the connection is closed. TypeError: If ``message`` doesn't have a supported type. """ # While sending a fragmented message, prevent sending other messages # until all fragments are sent. while self.fragmented_send_waiter is not None: await asyncio.shield(self.fragmented_send_waiter) # Unfragmented message -- this case must be handled first because # strings and bytes-like objects are iterable. if isinstance(message, str): async with self.send_context(): if text is False: self.protocol.send_binary(message.encode()) else: self.protocol.send_text(message.encode()) elif isinstance(message, BytesLike): async with self.send_context(): if text is True: self.protocol.send_text(message) else: self.protocol.send_binary(message) # Catch a common mistake -- passing a dict to send(). elif isinstance(message, Mapping): raise TypeError("data is a dict-like object") # Fragmented message -- regular iterator. elif isinstance(message, Iterable): chunks = iter(message) try: chunk = next(chunks) except StopIteration: return assert self.fragmented_send_waiter is None self.fragmented_send_waiter = self.loop.create_future() try: # First fragment. if isinstance(chunk, str): async with self.send_context(): if text is False: self.protocol.send_binary(chunk.encode(), fin=False) else: self.protocol.send_text(chunk.encode(), fin=False) encode = True elif isinstance(chunk, BytesLike): async with self.send_context(): if text is True: self.protocol.send_text(chunk, fin=False) else: self.protocol.send_binary(chunk, fin=False) encode = False else: raise TypeError("iterable must contain bytes or str") # Other fragments for chunk in chunks: if isinstance(chunk, str) and encode: async with self.send_context(): self.protocol.send_continuation(chunk.encode(), fin=False) elif isinstance(chunk, BytesLike) and not encode: async with self.send_context(): self.protocol.send_continuation(chunk, fin=False) else: raise TypeError("iterable must contain uniform types") # Final fragment. async with self.send_context(): self.protocol.send_continuation(b"", fin=True) except Exception: # We're half-way through a fragmented message and we can't # complete it. This makes the connection unusable. async with self.send_context(): self.protocol.fail( CloseCode.INTERNAL_ERROR, "error in fragmented message", ) raise finally: self.fragmented_send_waiter.set_result(None) self.fragmented_send_waiter = None # Fragmented message -- async iterator. elif isinstance(message, AsyncIterable): achunks = aiter(message) try: chunk = await anext(achunks) except StopAsyncIteration: return assert self.fragmented_send_waiter is None self.fragmented_send_waiter = self.loop.create_future() try: # First fragment. if isinstance(chunk, str): if text is False: async with self.send_context(): self.protocol.send_binary(chunk.encode(), fin=False) else: async with self.send_context(): self.protocol.send_text(chunk.encode(), fin=False) encode = True elif isinstance(chunk, BytesLike): if text is True: async with self.send_context(): self.protocol.send_text(chunk, fin=False) else: async with self.send_context(): self.protocol.send_binary(chunk, fin=False) encode = False else: raise TypeError("async iterable must contain bytes or str") # Other fragments async for chunk in achunks: if isinstance(chunk, str) and encode: async with self.send_context(): self.protocol.send_continuation(chunk.encode(), fin=False) elif isinstance(chunk, BytesLike) and not encode: async with self.send_context(): self.protocol.send_continuation(chunk, fin=False) else: raise TypeError("async iterable must contain uniform types") # Final fragment. async with self.send_context(): self.protocol.send_continuation(b"", fin=True) except Exception: # We're half-way through a fragmented message and we can't # complete it. This makes the connection unusable. async with self.send_context(): self.protocol.fail( CloseCode.INTERNAL_ERROR, "error in fragmented message", ) raise finally: self.fragmented_send_waiter.set_result(None) self.fragmented_send_waiter = None else: raise TypeError("data must be str, bytes, iterable, or async iterable") async def close(self, code: int = 1000, reason: str = "") -> None: """ Perform the closing handshake. :meth:`close` waits for the other end to complete the handshake and for the TCP connection to terminate. :meth:`close` is idempotent: it doesn't do anything once the connection is closed. Args: code: WebSocket close code. reason: WebSocket close reason. """ try: # The context manager takes care of waiting for the TCP connection # to terminate after calling a method that sends a close frame. async with self.send_context(): if self.fragmented_send_waiter is not None: self.protocol.fail( CloseCode.INTERNAL_ERROR, "close during fragmented message", ) else: self.protocol.send_close(code, reason) except ConnectionClosed: # Ignore ConnectionClosed exceptions raised from send_context(). # They mean that the connection is closed, which was the goal. pass async def wait_closed(self) -> None: """ Wait until the connection is closed. :meth:`wait_closed` waits for the closing handshake to complete and for the TCP connection to terminate. """ await asyncio.shield(self.connection_lost_waiter) async def ping(self, data: Data | None = None) -> Awaitable[float]: """ Send a Ping_. .. _Ping: https://datatracker.ietf.org/doc/html/rfc6455#section-5.5.2 A ping may serve as a keepalive or as a check that the remote endpoint received all messages up to this point Args: data: Payload of the ping. A :class:`str` will be encoded to UTF-8. If ``data`` is :obj:`None`, the payload is four random bytes. Returns: A future that will be completed when the corresponding pong is received. You can ignore it if you don't intend to wait. The result of the future is the latency of the connection in seconds. :: pong_waiter = await ws.ping() # only if you want to wait for the corresponding pong latency = await pong_waiter Raises: ConnectionClosed: When the connection is closed. ConcurrencyError: If another ping was sent with the same data and the corresponding pong wasn't received yet. """ if isinstance(data, BytesLike): data = bytes(data) elif isinstance(data, str): data = data.encode() elif data is not None: raise TypeError("data must be str or bytes-like") async with self.send_context(): # Protect against duplicates if a payload is explicitly set. if data in self.pong_waiters: raise ConcurrencyError("already waiting for a pong with the same data") # Generate a unique random payload otherwise. while data is None or data in self.pong_waiters: data = struct.pack("!I", random.getrandbits(32)) pong_waiter = self.loop.create_future() # The event loop's default clock is time.monotonic(). Its resolution # is a bit low on Windows (~16ms). This is improved in Python 3.13. self.pong_waiters[data] = (pong_waiter, self.loop.time()) self.protocol.send_ping(data) return pong_waiter async def pong(self, data: Data = b"") -> None: """ Send a Pong_. .. _Pong: https://datatracker.ietf.org/doc/html/rfc6455#section-5.5.3 An unsolicited pong may serve as a unidirectional heartbeat. Args: data: Payload of the pong. A :class:`str` will be encoded to UTF-8. Raises: ConnectionClosed: When the connection is closed. """ if isinstance(data, BytesLike): data = bytes(data) elif isinstance(data, str): data = data.encode() else: raise TypeError("data must be str or bytes-like") async with self.send_context(): self.protocol.send_pong(data) # Private methods def process_event(self, event: Event) -> None: """ Process one incoming event. This method is overridden in subclasses to handle the handshake. """ assert isinstance(event, Frame) if event.opcode in DATA_OPCODES: self.recv_messages.put(event) if event.opcode is Opcode.PONG: self.acknowledge_pings(bytes(event.data)) def acknowledge_pings(self, data: bytes) -> None: """ Acknowledge pings when receiving a pong. """ # Ignore unsolicited pong. if data not in self.pong_waiters: return pong_timestamp = self.loop.time() # Sending a pong for only the most recent ping is legal. # Acknowledge all previous pings too in that case. ping_id = None ping_ids = [] for ping_id, (pong_waiter, ping_timestamp) in self.pong_waiters.items(): ping_ids.append(ping_id) latency = pong_timestamp - ping_timestamp if not pong_waiter.done(): pong_waiter.set_result(latency) if ping_id == data: self.latency = latency break else: raise AssertionError("solicited pong not found in pings") # Remove acknowledged pings from self.pong_waiters. for ping_id in ping_ids: del self.pong_waiters[ping_id] def abort_pings(self) -> None: """ Raise ConnectionClosed in pending pings. They'll never receive a pong once the connection is closed. """ assert self.protocol.state is CLOSED exc = self.protocol.close_exc for pong_waiter, _ping_timestamp in self.pong_waiters.values(): if not pong_waiter.done(): pong_waiter.set_exception(exc) # If the exception is never retrieved, it will be logged when ping # is garbage-collected. This is confusing for users. # Given that ping is done (with an exception), canceling it does # nothing, but it prevents logging the exception. pong_waiter.cancel() self.pong_waiters.clear() async def keepalive(self) -> None: """ Send a Ping frame and wait for a Pong frame at regular intervals. """ assert self.ping_interval is not None latency = 0.0 try: while True: # If self.ping_timeout > latency > self.ping_interval, # pings will be sent immediately after receiving pongs. # The period will be longer than self.ping_interval. await asyncio.sleep(self.ping_interval - latency) # This cannot raise ConnectionClosed when the connection is # closing because ping(), via send_context(), waits for the # connection to be closed before raising ConnectionClosed. # However, connection_lost() cancels keepalive_task before # it gets a chance to resume excuting. pong_waiter = await self.ping() if self.debug: self.logger.debug("% sent keepalive ping") if self.ping_timeout is not None: try: async with asyncio_timeout(self.ping_timeout): # connection_lost cancels keepalive immediately # after setting a ConnectionClosed exception on # pong_waiter. A CancelledError is raised here, # not a ConnectionClosed exception. latency = await pong_waiter self.logger.debug("% received keepalive pong") except asyncio.TimeoutError: if self.debug: self.logger.debug("- timed out waiting for keepalive pong") async with self.send_context(): self.protocol.fail( CloseCode.INTERNAL_ERROR, "keepalive ping timeout", ) raise AssertionError( "send_context() should wait for connection_lost(), " "which cancels keepalive()" ) except Exception: self.logger.error("keepalive ping failed", exc_info=True) def start_keepalive(self) -> None: """ Run :meth:`keepalive` in a task, unless keepalive is disabled. """ if self.ping_interval is not None: self.keepalive_task = self.loop.create_task(self.keepalive()) @contextlib.asynccontextmanager async def send_context( self, *, expected_state: State = OPEN, # CONNECTING during the opening handshake ) -> AsyncIterator[None]: """ Create a context for writing to the connection from user code. On entry, :meth:`send_context` checks that the connection is open; on exit, it writes outgoing data to the socket:: async with self.send_context(): self.protocol.send_text(message.encode()) When the connection isn't open on entry, when the connection is expected to close on exit, or when an unexpected error happens, terminating the connection, :meth:`send_context` waits until the connection is closed then raises :exc:`~websockets.exceptions.ConnectionClosed`. """ # Should we wait until the connection is closed? wait_for_close = False # Should we close the transport and raise ConnectionClosed? raise_close_exc = False # What exception should we chain ConnectionClosed to? original_exc: BaseException | None = None if self.protocol.state is expected_state: # Let the caller interact with the protocol. try: yield except (ProtocolError, ConcurrencyError): # The protocol state wasn't changed. Exit immediately. raise except Exception as exc: self.logger.error("unexpected internal error", exc_info=True) # This branch should never run. It's a safety net in case of # bugs. Since we don't know what happened, we will close the # connection and raise the exception to the caller. wait_for_close = False raise_close_exc = True original_exc = exc else: # Check if the connection is expected to close soon. if self.protocol.close_expected(): wait_for_close = True # If the connection is expected to close soon, set the # close deadline based on the close timeout. # Since we tested earlier that protocol.state was OPEN # (or CONNECTING), self.close_deadline is still None. if self.close_timeout is not None: assert self.close_deadline is None self.close_deadline = self.loop.time() + self.close_timeout # Write outgoing data to the socket and enforce flow control. try: self.send_data() await self.drain() except Exception as exc: if self.debug: self.logger.debug("! error while sending data", exc_info=True) # While the only expected exception here is OSError, # other exceptions would be treated identically. wait_for_close = False raise_close_exc = True original_exc = exc else: # self.protocol.state is not expected_state # Minor layering violation: we assume that the connection # will be closing soon if it isn't in the expected state. wait_for_close = True # Calculate close_deadline if it wasn't set yet. if self.close_timeout is not None: if self.close_deadline is None: self.close_deadline = self.loop.time() + self.close_timeout raise_close_exc = True # If the connection is expected to close soon and the close timeout # elapses, close the socket to terminate the connection. if wait_for_close: try: async with asyncio_timeout_at(self.close_deadline): await asyncio.shield(self.connection_lost_waiter) except TimeoutError: # There's no risk to overwrite another error because # original_exc is never set when wait_for_close is True. assert original_exc is None original_exc = TimeoutError("timed out while closing connection") # Set recv_exc before closing the transport in order to get # proper exception reporting. raise_close_exc = True self.set_recv_exc(original_exc) # If an error occurred, close the transport to terminate the connection and # raise an exception. if raise_close_exc: self.transport.abort() # Wait for the protocol state to be CLOSED before accessing close_exc. await asyncio.shield(self.connection_lost_waiter) raise self.protocol.close_exc from original_exc def send_data(self) -> None: """ Send outgoing data. Raises: OSError: When a socket operations fails. """ for data in self.protocol.data_to_send(): if data: self.transport.write(data) else: # Half-close the TCP connection when possible i.e. no TLS. if self.transport.can_write_eof(): if self.debug: self.logger.debug("x half-closing TCP connection") # write_eof() doesn't document which exceptions it raises. # OSError is plausible. uvloop can raise RuntimeError here. try: self.transport.write_eof() except (OSError, RuntimeError): # pragma: no cover pass # Else, close the TCP connection. else: # pragma: no cover if self.debug: self.logger.debug("x closing TCP connection") self.transport.close() def set_recv_exc(self, exc: BaseException | None) -> None: """ Set recv_exc, if not set yet. """ if self.recv_exc is None: self.recv_exc = exc # asyncio.Protocol methods # Connection callbacks def connection_made(self, transport: asyncio.BaseTransport) -> None: transport = cast(asyncio.Transport, transport) self.recv_messages = Assembler( *self.max_queue, pause=transport.pause_reading, resume=transport.resume_reading, ) transport.set_write_buffer_limits(*self.write_limit) self.transport = transport def connection_lost(self, exc: Exception | None) -> None: # Calling protocol.receive_eof() is safe because it's idempotent. # This guarantees that the protocol state becomes CLOSED. self.protocol.receive_eof() assert self.protocol.state is CLOSED self.set_recv_exc(exc) # Abort recv() and pending pings with a ConnectionClosed exception. self.recv_messages.close() self.abort_pings() if self.keepalive_task is not None: self.keepalive_task.cancel() # If self.connection_lost_waiter isn't pending, that's a bug, because: # - it's set only here in connection_lost() which is called only once; # - it must never be canceled. self.connection_lost_waiter.set_result(None) # Adapted from asyncio.streams.FlowControlMixin if self.paused: # pragma: no cover self.paused = False for waiter in self.drain_waiters: if not waiter.done(): if exc is None: waiter.set_result(None) else: waiter.set_exception(exc) # Flow control callbacks def pause_writing(self) -> None: # pragma: no cover # Adapted from asyncio.streams.FlowControlMixin assert not self.paused self.paused = True def resume_writing(self) -> None: # pragma: no cover # Adapted from asyncio.streams.FlowControlMixin assert self.paused self.paused = False for waiter in self.drain_waiters: if not waiter.done(): waiter.set_result(None) async def drain(self) -> None: # pragma: no cover # We don't check if the connection is closed because we call drain() # immediately after write() and write() would fail in that case. # Adapted from asyncio.streams.StreamWriter # Yield to the event loop so that connection_lost() may be called. if self.transport.is_closing(): await asyncio.sleep(0) # Adapted from asyncio.streams.FlowControlMixin if self.paused: waiter = self.loop.create_future() self.drain_waiters.append(waiter) try: await waiter finally: self.drain_waiters.remove(waiter) # Streaming protocol callbacks def data_received(self, data: bytes) -> None: # Feed incoming data to the protocol. self.protocol.receive_data(data) # This isn't expected to raise an exception. events = self.protocol.events_received() # Write outgoing data to the transport. try: self.send_data() except Exception as exc: if self.debug: self.logger.debug("! error while sending data", exc_info=True) self.set_recv_exc(exc) if self.protocol.close_expected(): # If the connection is expected to close soon, set the # close deadline based on the close timeout. if self.close_timeout is not None: if self.close_deadline is None: self.close_deadline = self.loop.time() + self.close_timeout for event in events: # This isn't expected to raise an exception. self.process_event(event) def eof_received(self) -> None: # Feed the end of the data stream to the connection. self.protocol.receive_eof() # This isn't expected to raise an exception. events = self.protocol.events_received() # There is no error handling because send_data() can only write # the end of the data stream here and it shouldn't raise errors. self.send_data() # This code path is triggered when receiving an HTTP response # without a Content-Length header. This is the only case where # reading until EOF generates an event; all other events have # a known length. Ignore for coverage measurement because tests # are in test_client.py rather than test_connection.py. for event in events: # pragma: no cover # This isn't expected to raise an exception. self.process_event(event) # The WebSocket protocol has its own closing handshake: endpoints close # the TCP or TLS connection after sending and receiving a close frame. # As a consequence, they never need to write after receiving EOF, so # there's no reason to keep the transport open by returning True. # Besides, that doesn't work on TLS connections. # broadcast() is defined in the connection module even though it's primarily # used by servers and documented in the server module because it works with # client connections too and because it's easier to test together with the # Connection class. def broadcast( connections: Iterable[Connection], message: Data, raise_exceptions: bool = False, ) -> None: """ Broadcast a message to several WebSocket connections. A string (:class:`str`) is sent as a Text_ frame. A bytestring or bytes-like object (:class:`bytes`, :class:`bytearray`, or :class:`memoryview`) is sent as a Binary_ frame. .. _Text: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6 .. _Binary: https://datatracker.ietf.org/doc/html/rfc6455#section-5.6 :func:`broadcast` pushes the message synchronously to all connections even if their write buffers are overflowing. There's no backpressure. If you broadcast messages faster than a connection can handle them, messages will pile up in its write buffer until the connection times out. Keep ``ping_interval`` and ``ping_timeout`` low to prevent excessive memory usage from slow connections. Unlike :meth:`~websockets.asyncio.connection.Connection.send`, :func:`broadcast` doesn't support sending fragmented messages. Indeed, fragmentation is useful for sending large messages without buffering them in memory, while :func:`broadcast` buffers one copy per connection as fast as possible. :func:`broadcast` skips connections that aren't open in order to avoid errors on connections where the closing handshake is in progress. :func:`broadcast` ignores failures to write the message on some connections. It continues writing to other connections. On Python 3.11 and above, you may set ``raise_exceptions`` to :obj:`True` to record failures and raise all exceptions in a :pep:`654` :exc:`ExceptionGroup`. While :func:`broadcast` makes more sense for servers, it works identically with clients, if you have a use case for opening connections to many servers and broadcasting a message to them. Args: websockets: WebSocket connections to which the message will be sent. message: Message to send. raise_exceptions: Whether to raise an exception in case of failures. Raises: TypeError: If ``message`` doesn't have a supported type. """ if isinstance(message, str): send_method = "send_text" message = message.encode() elif isinstance(message, BytesLike): send_method = "send_binary" else: raise TypeError("data must be str or bytes") if raise_exceptions: if sys.version_info[:2] < (3, 11): # pragma: no cover raise ValueError("raise_exceptions requires at least Python 3.11") exceptions: list[Exception] = [] for connection in connections: exception: Exception if connection.protocol.state is not OPEN: continue if connection.fragmented_send_waiter is not None: if raise_exceptions: exception = ConcurrencyError("sending a fragmented message") exceptions.append(exception) else: connection.logger.warning( "skipped broadcast: sending a fragmented message", ) continue try: # Call connection.protocol.send_text or send_binary. # Either way, message is already converted to bytes. getattr(connection.protocol, send_method)(message) connection.send_data() except Exception as write_exception: if raise_exceptions: exception = RuntimeError("failed to write message") exception.__cause__ = write_exception exceptions.append(exception) else: connection.logger.warning( "skipped broadcast: failed to write message: %s", traceback.format_exception_only( # Remove first argument when dropping Python 3.9. type(write_exception), write_exception, )[0].strip(), ) if raise_exceptions and exceptions: raise ExceptionGroup("skipped broadcast", exceptions) # Pretend that broadcast is actually defined in the server module. broadcast.__module__ = "websockets.asyncio.server"