Source code for tornado.websocket

"""Implementation of the WebSocket protocol.

`WebSockets <>`_ allow for bidirectional
communication between the browser and server. WebSockets are supported in the
current versions of all major browsers.

This module implements the final version of the WebSocket protocol as
defined in `RFC 6455 <>`_.

.. versionchanged:: 4.0
   Removed support for the draft 76 protocol version.

import abc
import asyncio
import base64
import hashlib
import os
import sys
import struct
import tornado
from urllib.parse import urlparse
import warnings
import zlib

from tornado.concurrent import Future, future_set_result_unless_cancelled
from tornado.escape import utf8, native_str, to_unicode
from tornado import gen, httpclient, httputil
from tornado.ioloop import IOLoop, PeriodicCallback
from tornado.iostream import StreamClosedError, IOStream
from tornado.log import gen_log, app_log
from tornado.netutil import Resolver
from tornado import simple_httpclient
from tornado.queues import Queue
from tornado.tcpclient import TCPClient
from tornado.util import _websocket_mask

from typing import (
from types import TracebackType

    from typing_extensions import Protocol

    # The zlib compressor types aren't actually exposed anywhere
    # publicly, so declare protocols for the portions we use.
    class _Compressor(Protocol):
        def compress(self, data: bytes) -> bytes:

        def flush(self, mode: int) -> bytes:

    class _Decompressor(Protocol):
        unconsumed_tail = b""  # type: bytes

        def decompress(self, data: bytes, max_length: int) -> bytes:

    class _WebSocketDelegate(Protocol):
        # The common base interface implemented by WebSocketHandler on
        # the server side and WebSocketClientConnection on the client
        # side.
        def on_ws_connection_close(
            self, close_code: Optional[int] = None, close_reason: Optional[str] = None
        ) -> None:

        def on_message(self, message: Union[str, bytes]) -> Optional["Awaitable[None]"]:

        def on_ping(self, data: bytes) -> None:

        def on_pong(self, data: bytes) -> None:

        def log_exception(
            typ: Optional[Type[BaseException]],
            value: Optional[BaseException],
            tb: Optional[TracebackType],
        ) -> None:

_default_max_message_size = 10 * 1024 * 1024

class WebSocketError(Exception):

[docs]class WebSocketClosedError(WebSocketError): """Raised by operations on a closed connection. .. versionadded:: 3.2 """ pass
class _DecompressTooLargeError(Exception): pass class _WebSocketParams(object): def __init__( self, ping_interval: Optional[float] = None, ping_timeout: Optional[float] = None, max_message_size: int = _default_max_message_size, compression_options: Optional[Dict[str, Any]] = None, ) -> None: self.ping_interval = ping_interval self.ping_timeout = ping_timeout self.max_message_size = max_message_size self.compression_options = compression_options
[docs]class WebSocketHandler(tornado.web.RequestHandler): """Subclass this class to create a basic WebSocket handler. Override `on_message` to handle incoming messages, and use `write_message` to send messages to the client. You can also override `open` and `on_close` to handle opened and closed connections. Custom upgrade response headers can be sent by overriding `~tornado.web.RequestHandler.set_default_headers` or `~tornado.web.RequestHandler.prepare`. See for details on the JavaScript interface. The protocol is specified at Here is an example WebSocket handler that echos back all received messages back to the client: .. testcode:: class EchoWebSocket(tornado.websocket.WebSocketHandler): def open(self): print("WebSocket opened") def on_message(self, message): self.write_message(u"You said: " + message) def on_close(self): print("WebSocket closed") .. testoutput:: :hide: WebSockets are not standard HTTP connections. The "handshake" is HTTP, but after the handshake, the protocol is message-based. Consequently, most of the Tornado HTTP facilities are not available in handlers of this type. The only communication methods available to you are `write_message()`, `ping()`, and `close()`. Likewise, your request handler class should implement `open()` method rather than ``get()`` or ``post()``. If you map the handler above to ``/websocket`` in your application, you can invoke it in JavaScript with:: var ws = new WebSocket("ws://localhost:8888/websocket"); ws.onopen = function() { ws.send("Hello, world"); }; ws.onmessage = function (evt) { alert(; }; This script pops up an alert box that says "You said: Hello, world". Web browsers allow any site to open a websocket connection to any other, instead of using the same-origin policy that governs other network access from JavaScript. This can be surprising and is a potential security hole, so since Tornado 4.0 `WebSocketHandler` requires applications that wish to receive cross-origin websockets to opt in by overriding the `~WebSocketHandler.check_origin` method (see that method's docs for details). Failure to do so is the most likely cause of 403 errors when making a websocket connection. When using a secure websocket connection (``wss://``) with a self-signed certificate, the connection from a browser may fail because it wants to show the "accept this certificate" dialog but has nowhere to show it. You must first visit a regular HTML page using the same certificate to accept it before the websocket connection will succeed. If the application setting ``websocket_ping_interval`` has a non-zero value, a ping will be sent periodically, and the connection will be closed if a response is not received before the ``websocket_ping_timeout``. Messages larger than the ``websocket_max_message_size`` application setting (default 10MiB) will not be accepted. .. versionchanged:: 4.5 Added ``websocket_ping_interval``, ``websocket_ping_timeout``, and ``websocket_max_message_size``. """ def __init__( self, application: tornado.web.Application, request: httputil.HTTPServerRequest, **kwargs: Any ) -> None: super().__init__(application, request, **kwargs) self.ws_connection = None # type: Optional[WebSocketProtocol] self.close_code = None # type: Optional[int] self.close_reason = None # type: Optional[str] self._on_close_called = False async def get(self, *args: Any, **kwargs: Any) -> None: self.open_args = args self.open_kwargs = kwargs # Upgrade header should be present and should be equal to WebSocket if self.request.headers.get("Upgrade", "").lower() != "websocket": self.set_status(400) log_msg = 'Can "Upgrade" only to "WebSocket".' self.finish(log_msg) gen_log.debug(log_msg) return # Connection header should be upgrade. # Some proxy servers/load balancers # might mess with it. headers = self.request.headers connection = map( lambda s: s.strip().lower(), headers.get("Connection", "").split(",") ) if "upgrade" not in connection: self.set_status(400) log_msg = '"Connection" must be "Upgrade".' self.finish(log_msg) gen_log.debug(log_msg) return # Handle WebSocket Origin naming convention differences # The difference between version 8 and 13 is that in 8 the # client sends a "Sec-Websocket-Origin" header and in 13 it's # simply "Origin". if "Origin" in self.request.headers: origin = self.request.headers.get("Origin") else: origin = self.request.headers.get("Sec-Websocket-Origin", None) # If there was an origin header, check to make sure it matches # according to check_origin. When the origin is None, we assume it # did not come from a browser and that it can be passed on. if origin is not None and not self.check_origin(origin): self.set_status(403) log_msg = "Cross origin websockets not allowed" self.finish(log_msg) gen_log.debug(log_msg) return self.ws_connection = self.get_websocket_protocol() if self.ws_connection: await self.ws_connection.accept_connection(self) else: self.set_status(426, "Upgrade Required") self.set_header("Sec-WebSocket-Version", "7, 8, 13") @property def ping_interval(self) -> Optional[float]: """The interval for websocket keep-alive pings. Set websocket_ping_interval = 0 to disable pings. """ return self.settings.get("websocket_ping_interval", None) @property def ping_timeout(self) -> Optional[float]: """If no ping is received in this many seconds, close the websocket connection (VPNs, etc. can fail to cleanly close ws connections). Default is max of 3 pings or 30 seconds. """ return self.settings.get("websocket_ping_timeout", None) @property def max_message_size(self) -> int: """Maximum allowed message size. If the remote peer sends a message larger than this, the connection will be closed. Default is 10MiB. """ return self.settings.get( "websocket_max_message_size", _default_max_message_size )
[docs] def write_message( self, message: Union[bytes, str, Dict[str, Any]], binary: bool = False ) -> "Future[None]": """Sends the given message to the client of this Web Socket. The message may be either a string or a dict (which will be encoded as json). If the ``binary`` argument is false, the message will be sent as utf8; in binary mode any byte string is allowed. If the connection is already closed, raises `WebSocketClosedError`. Returns a `.Future` which can be used for flow control. .. versionchanged:: 3.2 `WebSocketClosedError` was added (previously a closed connection would raise an `AttributeError`) .. versionchanged:: 4.3 Returns a `.Future` which can be used for flow control. .. versionchanged:: 5.0 Consistently raises `WebSocketClosedError`. Previously could sometimes raise `.StreamClosedError`. """ if self.ws_connection is None or self.ws_connection.is_closing(): raise WebSocketClosedError() if isinstance(message, dict): message = tornado.escape.json_encode(message) return self.ws_connection.write_message(message, binary=binary)
[docs] def select_subprotocol(self, subprotocols: List[str]) -> Optional[str]: """Override to implement subprotocol negotiation. ``subprotocols`` is a list of strings identifying the subprotocols proposed by the client. This method may be overridden to return one of those strings to select it, or ``None`` to not select a subprotocol. Failure to select a subprotocol does not automatically abort the connection, although clients may close the connection if none of their proposed subprotocols was selected. The list may be empty, in which case this method must return None. This method is always called exactly once even if no subprotocols were proposed so that the handler can be advised of this fact. .. versionchanged:: 5.1 Previously, this method was called with a list containing an empty string instead of an empty list if no subprotocols were proposed by the client. """ return None
@property def selected_subprotocol(self) -> Optional[str]: """The subprotocol returned by `select_subprotocol`. .. versionadded:: 5.1 """ assert self.ws_connection is not None return self.ws_connection.selected_subprotocol
[docs] def get_compression_options(self) -> Optional[Dict[str, Any]]: """Override to return compression options for the connection. If this method returns None (the default), compression will be disabled. If it returns a dict (even an empty one), it will be enabled. The contents of the dict may be used to control the following compression options: ``compression_level`` specifies the compression level. ``mem_level`` specifies the amount of memory used for the internal compression state. These parameters are documented in details here: .. versionadded:: 4.1 .. versionchanged:: 4.5 Added ``compression_level`` and ``mem_level``. """ # TODO: Add wbits option. return None
[docs] def open(self, *args: str, **kwargs: str) -> Optional[Awaitable[None]]: """Invoked when a new WebSocket is opened. The arguments to `open` are extracted from the `tornado.web.URLSpec` regular expression, just like the arguments to `tornado.web.RequestHandler.get`. `open` may be a coroutine. `on_message` will not be called until `open` has returned. .. versionchanged:: 5.1 ``open`` may be a coroutine. """ pass
[docs] def on_message(self, message: Union[str, bytes]) -> Optional[Awaitable[None]]: """Handle incoming messages on the WebSocket This method must be overridden. .. versionchanged:: 4.5 ``on_message`` can be a coroutine. """ raise NotImplementedError
[docs] def ping(self, data: Union[str, bytes] = b"") -> None: """Send ping frame to the remote end. The data argument allows a small amount of data (up to 125 bytes) to be sent as a part of the ping message. Note that not all websocket implementations expose this data to applications. Consider using the ``websocket_ping_interval`` application setting instead of sending pings manually. .. versionchanged:: 5.1 The data argument is now optional. """ data = utf8(data) if self.ws_connection is None or self.ws_connection.is_closing(): raise WebSocketClosedError() self.ws_connection.write_ping(data)
[docs] def on_pong(self, data: bytes) -> None: """Invoked when the response to a ping frame is received.""" pass
[docs] def on_ping(self, data: bytes) -> None: """Invoked when the a ping frame is received.""" pass
[docs] def on_close(self) -> None: """Invoked when the WebSocket is closed. If the connection was closed cleanly and a status code or reason phrase was supplied, these values will be available as the attributes ``self.close_code`` and ``self.close_reason``. .. versionchanged:: 4.0 Added ``close_code`` and ``close_reason`` attributes. """ pass
[docs] def close(self, code: Optional[int] = None, reason: Optional[str] = None) -> None: """Closes this Web Socket. Once the close handshake is successful the socket will be closed. ``code`` may be a numeric status code, taken from the values defined in `RFC 6455 section 7.4.1 <>`_. ``reason`` may be a textual message about why the connection is closing. These values are made available to the client, but are not otherwise interpreted by the websocket protocol. .. versionchanged:: 4.0 Added the ``code`` and ``reason`` arguments. """ if self.ws_connection: self.ws_connection.close(code, reason) self.ws_connection = None
[docs] def check_origin(self, origin: str) -> bool: """Override to enable support for allowing alternate origins. The ``origin`` argument is the value of the ``Origin`` HTTP header, the url responsible for initiating this request. This method is not called for clients that do not send this header; such requests are always allowed (because all browsers that implement WebSockets support this header, and non-browser clients do not have the same cross-site security concerns). Should return ``True`` to accept the request or ``False`` to reject it. By default, rejects all requests with an origin on a host other than this one. This is a security protection against cross site scripting attacks on browsers, since WebSockets are allowed to bypass the usual same-origin policies and don't use CORS headers. .. warning:: This is an important security measure; don't disable it without understanding the security implications. In particular, if your authentication is cookie-based, you must either restrict the origins allowed by ``check_origin()`` or implement your own XSRF-like protection for websocket connections. See `these <>`_ `articles <>`_ for more. To accept all cross-origin traffic (which was the default prior to Tornado 4.0), simply override this method to always return ``True``:: def check_origin(self, origin): return True To allow connections from any subdomain of your site, you might do something like:: def check_origin(self, origin): parsed_origin = urllib.parse.urlparse(origin) return parsed_origin.netloc.endswith("") .. versionadded:: 4.0 """ parsed_origin = urlparse(origin) origin = parsed_origin.netloc origin = origin.lower() host = self.request.headers.get("Host") # Check to see that origin matches host directly, including ports return origin == host
[docs] def set_nodelay(self, value: bool) -> None: """Set the no-delay flag for this stream. By default, small messages may be delayed and/or combined to minimize the number of packets sent. This can sometimes cause 200-500ms delays due to the interaction between Nagle's algorithm and TCP delayed ACKs. To reduce this delay (at the expense of possibly increasing bandwidth usage), call ``self.set_nodelay(True)`` once the websocket connection is established. See `.BaseIOStream.set_nodelay` for additional details. .. versionadded:: 3.1 """ assert self.ws_connection is not None self.ws_connection.set_nodelay(value)
def on_connection_close(self) -> None: if self.ws_connection: self.ws_connection.on_connection_close() self.ws_connection = None if not self._on_close_called: self._on_close_called = True self.on_close() self._break_cycles() def on_ws_connection_close( self, close_code: Optional[int] = None, close_reason: Optional[str] = None ) -> None: self.close_code = close_code self.close_reason = close_reason self.on_connection_close() def _break_cycles(self) -> None: # WebSocketHandlers call finish() early, but we don't want to # break up reference cycles (which makes it impossible to call # self.render_string) until after we've really closed the # connection (if it was established in the first place, # indicated by status code 101). if self.get_status() != 101 or self._on_close_called: super()._break_cycles() def get_websocket_protocol(self) -> Optional["WebSocketProtocol"]: websocket_version = self.request.headers.get("Sec-WebSocket-Version") if websocket_version in ("7", "8", "13"): params = _WebSocketParams( ping_interval=self.ping_interval, ping_timeout=self.ping_timeout, max_message_size=self.max_message_size, compression_options=self.get_compression_options(), ) return WebSocketProtocol13(self, False, params) return None def _detach_stream(self) -> IOStream: # disable non-WS methods for method in [ "write", "redirect", "set_header", "set_cookie", "set_status", "flush", "finish", ]: setattr(self, method, _raise_not_supported_for_websockets) return self.detach()
def _raise_not_supported_for_websockets(*args: Any, **kwargs: Any) -> None: raise RuntimeError("Method not supported for Web Sockets") class WebSocketProtocol(abc.ABC): """Base class for WebSocket protocol versions.""" def __init__(self, handler: "_WebSocketDelegate") -> None: self.handler = handler = None # type: Optional[IOStream] self.client_terminated = False self.server_terminated = False def _run_callback( self, callback: Callable, *args: Any, **kwargs: Any ) -> "Optional[Future[Any]]": """Runs the given callback with exception handling. If the callback is a coroutine, returns its Future. On error, aborts the websocket connection and returns None. """ try: result = callback(*args, **kwargs) except Exception: self.handler.log_exception(*sys.exc_info()) self._abort() return None else: if result is not None: result = gen.convert_yielded(result) assert is not None, lambda f: f.result()) return result def on_connection_close(self) -> None: self._abort() def _abort(self) -> None: """Instantly aborts the WebSocket connection by closing the socket""" self.client_terminated = True self.server_terminated = True if is not None: # forcibly tear down the connection self.close() # let the subclass cleanup @abc.abstractmethod def close(self, code: Optional[int] = None, reason: Optional[str] = None) -> None: raise NotImplementedError() @abc.abstractmethod def is_closing(self) -> bool: raise NotImplementedError() @abc.abstractmethod async def accept_connection(self, handler: WebSocketHandler) -> None: raise NotImplementedError() @abc.abstractmethod def write_message( self, message: Union[str, bytes, Dict[str, Any]], binary: bool = False ) -> "Future[None]": raise NotImplementedError() @property @abc.abstractmethod def selected_subprotocol(self) -> Optional[str]: raise NotImplementedError() @abc.abstractmethod def write_ping(self, data: bytes) -> None: raise NotImplementedError() # The entry points below are used by WebSocketClientConnection, # which was introduced after we only supported a single version of # WebSocketProtocol. The WebSocketProtocol/WebSocketProtocol13 # boundary is currently pretty ad-hoc. @abc.abstractmethod def _process_server_headers( self, key: Union[str, bytes], headers: httputil.HTTPHeaders ) -> None: raise NotImplementedError() @abc.abstractmethod def start_pinging(self) -> None: raise NotImplementedError() @abc.abstractmethod async def _receive_frame_loop(self) -> None: raise NotImplementedError() @abc.abstractmethod def set_nodelay(self, x: bool) -> None: raise NotImplementedError() class _PerMessageDeflateCompressor(object): def __init__( self, persistent: bool, max_wbits: Optional[int], compression_options: Optional[Dict[str, Any]] = None, ) -> None: if max_wbits is None: max_wbits = zlib.MAX_WBITS # There is no symbolic constant for the minimum wbits value. if not (8 <= max_wbits <= zlib.MAX_WBITS): raise ValueError( "Invalid max_wbits value %r; allowed range 8-%d", max_wbits, zlib.MAX_WBITS, ) self._max_wbits = max_wbits if ( compression_options is None or "compression_level" not in compression_options ): self._compression_level = tornado.web.GZipContentEncoding.GZIP_LEVEL else: self._compression_level = compression_options["compression_level"] if compression_options is None or "mem_level" not in compression_options: self._mem_level = 8 else: self._mem_level = compression_options["mem_level"] if persistent: self._compressor = self._create_compressor() # type: Optional[_Compressor] else: self._compressor = None def _create_compressor(self) -> "_Compressor": return zlib.compressobj( self._compression_level, zlib.DEFLATED, -self._max_wbits, self._mem_level ) def compress(self, data: bytes) -> bytes: compressor = self._compressor or self._create_compressor() data = compressor.compress(data) + compressor.flush(zlib.Z_SYNC_FLUSH) assert data.endswith(b"\x00\x00\xff\xff") return data[:-4] class _PerMessageDeflateDecompressor(object): def __init__( self, persistent: bool, max_wbits: Optional[int], max_message_size: int, compression_options: Optional[Dict[str, Any]] = None, ) -> None: self._max_message_size = max_message_size if max_wbits is None: max_wbits = zlib.MAX_WBITS if not (8 <= max_wbits <= zlib.MAX_WBITS): raise ValueError( "Invalid max_wbits value %r; allowed range 8-%d", max_wbits, zlib.MAX_WBITS, ) self._max_wbits = max_wbits if persistent: self._decompressor = ( self._create_decompressor() ) # type: Optional[_Decompressor] else: self._decompressor = None def _create_decompressor(self) -> "_Decompressor": return zlib.decompressobj(-self._max_wbits) def decompress(self, data: bytes) -> bytes: decompressor = self._decompressor or self._create_decompressor() result = decompressor.decompress( data + b"\x00\x00\xff\xff", self._max_message_size ) if decompressor.unconsumed_tail: raise _DecompressTooLargeError() return result class WebSocketProtocol13(WebSocketProtocol): """Implementation of the WebSocket protocol from RFC 6455. This class supports versions 7 and 8 of the protocol in addition to the final version 13. """ # Bit masks for the first byte of a frame. FIN = 0x80 RSV1 = 0x40 RSV2 = 0x20 RSV3 = 0x10 RSV_MASK = RSV1 | RSV2 | RSV3 OPCODE_MASK = 0x0F stream = None # type: IOStream def __init__( self, handler: "_WebSocketDelegate", mask_outgoing: bool, params: _WebSocketParams, ) -> None: WebSocketProtocol.__init__(self, handler) self.mask_outgoing = mask_outgoing self.params = params self._final_frame = False self._frame_opcode = None self._masked_frame = None self._frame_mask = None # type: Optional[bytes] self._frame_length = None self._fragmented_message_buffer = None # type: Optional[bytearray] self._fragmented_message_opcode = None self._waiting = None # type: object self._compression_options = params.compression_options self._decompressor = None # type: Optional[_PerMessageDeflateDecompressor] self._compressor = None # type: Optional[_PerMessageDeflateCompressor] self._frame_compressed = None # type: Optional[bool] # The total uncompressed size of all messages received or sent. # Unicode messages are encoded to utf8. # Only for testing; subject to change. self._message_bytes_in = 0 self._message_bytes_out = 0 # The total size of all packets received or sent. Includes # the effect of compression, frame overhead, and control frames. self._wire_bytes_in = 0 self._wire_bytes_out = 0 self.ping_callback = None # type: Optional[PeriodicCallback] self.last_ping = 0.0 self.last_pong = 0.0 self.close_code = None # type: Optional[int] self.close_reason = None # type: Optional[str] # Use a property for this to satisfy the abc. @property def selected_subprotocol(self) -> Optional[str]: return self._selected_subprotocol @selected_subprotocol.setter def selected_subprotocol(self, value: Optional[str]) -> None: self._selected_subprotocol = value async def accept_connection(self, handler: WebSocketHandler) -> None: try: self._handle_websocket_headers(handler) except ValueError: handler.set_status(400) log_msg = "Missing/Invalid WebSocket headers" handler.finish(log_msg) gen_log.debug(log_msg) return try: await self._accept_connection(handler) except asyncio.CancelledError: self._abort() return except ValueError: gen_log.debug("Malformed WebSocket request received", exc_info=True) self._abort() return def _handle_websocket_headers(self, handler: WebSocketHandler) -> None: """Verifies all invariant- and required headers If a header is missing or have an incorrect value ValueError will be raised """ fields = ("Host", "Sec-Websocket-Key", "Sec-Websocket-Version") if not all(map(lambda f: handler.request.headers.get(f), fields)): raise ValueError("Missing/Invalid WebSocket headers") @staticmethod def compute_accept_value(key: Union[str, bytes]) -> str: """Computes the value for the Sec-WebSocket-Accept header, given the value for Sec-WebSocket-Key. """ sha1 = hashlib.sha1() sha1.update(utf8(key)) sha1.update(b"258EAFA5-E914-47DA-95CA-C5AB0DC85B11") # Magic value return native_str(base64.b64encode(sha1.digest())) def _challenge_response(self, handler: WebSocketHandler) -> str: return WebSocketProtocol13.compute_accept_value( cast(str, handler.request.headers.get("Sec-Websocket-Key")) ) async def _accept_connection(self, handler: WebSocketHandler) -> None: subprotocol_header = handler.request.headers.get("Sec-WebSocket-Protocol") if subprotocol_header: subprotocols = [s.strip() for s in subprotocol_header.split(",")] else: subprotocols = [] self.selected_subprotocol = handler.select_subprotocol(subprotocols) if self.selected_subprotocol: assert self.selected_subprotocol in subprotocols handler.set_header("Sec-WebSocket-Protocol", self.selected_subprotocol) extensions = self._parse_extensions_header(handler.request.headers) for ext in extensions: if ext[0] == "permessage-deflate" and self._compression_options is not None: # TODO: negotiate parameters if compression_options # specifies limits. self._create_compressors("server", ext[1], self._compression_options) if ( "client_max_window_bits" in ext[1] and ext[1]["client_max_window_bits"] is None ): # Don't echo an offered client_max_window_bits # parameter with no value. del ext[1]["client_max_window_bits"] handler.set_header( "Sec-WebSocket-Extensions", httputil._encode_header("permessage-deflate", ext[1]), ) break handler.clear_header("Content-Type") handler.set_status(101) handler.set_header("Upgrade", "websocket") handler.set_header("Connection", "Upgrade") handler.set_header("Sec-WebSocket-Accept", self._challenge_response(handler)) handler.finish() = handler._detach_stream() self.start_pinging() try: open_result =*handler.open_args, **handler.open_kwargs) if open_result is not None: await open_result except Exception: handler.log_exception(*sys.exc_info()) self._abort() return await self._receive_frame_loop() def _parse_extensions_header( self, headers: httputil.HTTPHeaders ) -> List[Tuple[str, Dict[str, str]]]: extensions = headers.get("Sec-WebSocket-Extensions", "") if extensions: return [httputil._parse_header(e.strip()) for e in extensions.split(",")] return [] def _process_server_headers( self, key: Union[str, bytes], headers: httputil.HTTPHeaders ) -> None: """Process the headers sent by the server to this client connection. 'key' is the websocket handshake challenge/response key. """ assert headers["Upgrade"].lower() == "websocket" assert headers["Connection"].lower() == "upgrade" accept = self.compute_accept_value(key) assert headers["Sec-Websocket-Accept"] == accept extensions = self._parse_extensions_header(headers) for ext in extensions: if ext[0] == "permessage-deflate" and self._compression_options is not None: self._create_compressors("client", ext[1]) else: raise ValueError("unsupported extension %r", ext) self.selected_subprotocol = headers.get("Sec-WebSocket-Protocol", None) def _get_compressor_options( self, side: str, agreed_parameters: Dict[str, Any], compression_options: Optional[Dict[str, Any]] = None, ) -> Dict[str, Any]: """Converts a websocket agreed_parameters set to keyword arguments for our compressor objects. """ options = dict( persistent=(side + "_no_context_takeover") not in agreed_parameters ) # type: Dict[str, Any] wbits_header = agreed_parameters.get(side + "_max_window_bits", None) if wbits_header is None: options["max_wbits"] = zlib.MAX_WBITS else: options["max_wbits"] = int(wbits_header) options["compression_options"] = compression_options return options def _create_compressors( self, side: str, agreed_parameters: Dict[str, Any], compression_options: Optional[Dict[str, Any]] = None, ) -> None: # TODO: handle invalid parameters gracefully allowed_keys = set( [ "server_no_context_takeover", "client_no_context_takeover", "server_max_window_bits", "client_max_window_bits", ] ) for key in agreed_parameters: if key not in allowed_keys: raise ValueError("unsupported compression parameter %r" % key) other_side = "client" if (side == "server") else "server" self._compressor = _PerMessageDeflateCompressor( **self._get_compressor_options(side, agreed_parameters, compression_options) ) self._decompressor = _PerMessageDeflateDecompressor( max_message_size=self.params.max_message_size, **self._get_compressor_options( other_side, agreed_parameters, compression_options ) ) def _write_frame( self, fin: bool, opcode: int, data: bytes, flags: int = 0 ) -> "Future[None]": data_len = len(data) if opcode & 0x8: # All control frames MUST have a payload length of 125 # bytes or less and MUST NOT be fragmented. if not fin: raise ValueError("control frames may not be fragmented") if data_len > 125: raise ValueError("control frame payloads may not exceed 125 bytes") if fin: finbit = self.FIN else: finbit = 0 frame = struct.pack("B", finbit | opcode | flags) if self.mask_outgoing: mask_bit = 0x80 else: mask_bit = 0 if data_len < 126: frame += struct.pack("B", data_len | mask_bit) elif data_len <= 0xFFFF: frame += struct.pack("!BH", 126 | mask_bit, data_len) else: frame += struct.pack("!BQ", 127 | mask_bit, data_len) if self.mask_outgoing: mask = os.urandom(4) data = mask + _websocket_mask(mask, data) frame += data self._wire_bytes_out += len(frame) return def write_message( self, message: Union[str, bytes, Dict[str, Any]], binary: bool = False ) -> "Future[None]": """Sends the given message to the client of this Web Socket.""" if binary: opcode = 0x2 else: opcode = 0x1 if isinstance(message, dict): message = tornado.escape.json_encode(message) message = tornado.escape.utf8(message) assert isinstance(message, bytes) self._message_bytes_out += len(message) flags = 0 if self._compressor: message = self._compressor.compress(message) flags |= self.RSV1 # For historical reasons, write methods in Tornado operate in a semi-synchronous # mode in which awaiting the Future they return is optional (But errors can # still be raised). This requires us to go through an awkward dance here # to transform the errors that may be returned while presenting the same # semi-synchronous interface. try: fut = self._write_frame(True, opcode, message, flags=flags) except StreamClosedError: raise WebSocketClosedError() async def wrapper() -> None: try: await fut except StreamClosedError: raise WebSocketClosedError() return asyncio.ensure_future(wrapper()) def write_ping(self, data: bytes) -> None: """Send ping frame.""" assert isinstance(data, bytes) self._write_frame(True, 0x9, data) async def _receive_frame_loop(self) -> None: try: while not self.client_terminated: await self._receive_frame() except StreamClosedError: self._abort() self.handler.on_ws_connection_close(self.close_code, self.close_reason) async def _read_bytes(self, n: int) -> bytes: data = await self._wire_bytes_in += n return data async def _receive_frame(self) -> None: # Read the frame header. data = await self._read_bytes(2) header, mask_payloadlen = struct.unpack("BB", data) is_final_frame = header & self.FIN reserved_bits = header & self.RSV_MASK opcode = header & self.OPCODE_MASK opcode_is_control = opcode & 0x8 if self._decompressor is not None and opcode != 0: # Compression flag is present in the first frame's header, # but we can't decompress until we have all the frames of # the message. self._frame_compressed = bool(reserved_bits & self.RSV1) reserved_bits &= ~self.RSV1 if reserved_bits: # client is using as-yet-undefined extensions; abort self._abort() return is_masked = bool(mask_payloadlen & 0x80) payloadlen = mask_payloadlen & 0x7F # Parse and validate the length. if opcode_is_control and payloadlen >= 126: # control frames must have payload < 126 self._abort() return if payloadlen < 126: self._frame_length = payloadlen elif payloadlen == 126: data = await self._read_bytes(2) payloadlen = struct.unpack("!H", data)[0] elif payloadlen == 127: data = await self._read_bytes(8) payloadlen = struct.unpack("!Q", data)[0] new_len = payloadlen if self._fragmented_message_buffer is not None: new_len += len(self._fragmented_message_buffer) if new_len > self.params.max_message_size: self.close(1009, "message too big") self._abort() return # Read the payload, unmasking if necessary. if is_masked: self._frame_mask = await self._read_bytes(4) data = await self._read_bytes(payloadlen) if is_masked: assert self._frame_mask is not None data = _websocket_mask(self._frame_mask, data) # Decide what to do with this frame. if opcode_is_control: # control frames may be interleaved with a series of fragmented # data frames, so control frames must not interact with # self._fragmented_* if not is_final_frame: # control frames must not be fragmented self._abort() return elif opcode == 0: # continuation frame if self._fragmented_message_buffer is None: # nothing to continue self._abort() return self._fragmented_message_buffer.extend(data) if is_final_frame: opcode = self._fragmented_message_opcode data = bytes(self._fragmented_message_buffer) self._fragmented_message_buffer = None else: # start of new data message if self._fragmented_message_buffer is not None: # can't start new message until the old one is finished self._abort() return if not is_final_frame: self._fragmented_message_opcode = opcode self._fragmented_message_buffer = bytearray(data) if is_final_frame: handled_future = self._handle_message(opcode, data) if handled_future is not None: await handled_future def _handle_message(self, opcode: int, data: bytes) -> "Optional[Future[None]]": """Execute on_message, returning its Future if it is a coroutine.""" if self.client_terminated: return None if self._frame_compressed: assert self._decompressor is not None try: data = self._decompressor.decompress(data) except _DecompressTooLargeError: self.close(1009, "message too big after decompression") self._abort() return None if opcode == 0x1: # UTF-8 data self._message_bytes_in += len(data) try: decoded = data.decode("utf-8") except UnicodeDecodeError: self._abort() return None return self._run_callback(self.handler.on_message, decoded) elif opcode == 0x2: # Binary data self._message_bytes_in += len(data) return self._run_callback(self.handler.on_message, data) elif opcode == 0x8: # Close self.client_terminated = True if len(data) >= 2: self.close_code = struct.unpack(">H", data[:2])[0] if len(data) > 2: self.close_reason = to_unicode(data[2:]) # Echo the received close code, if any (RFC 6455 section 5.5.1). self.close(self.close_code) elif opcode == 0x9: # Ping try: self._write_frame(True, 0xA, data) except StreamClosedError: self._abort() self._run_callback(self.handler.on_ping, data) elif opcode == 0xA: # Pong self.last_pong = IOLoop.current().time() return self._run_callback(self.handler.on_pong, data) else: self._abort() return None def close(self, code: Optional[int] = None, reason: Optional[str] = None) -> None: """Closes the WebSocket connection.""" if not self.server_terminated: if not if code is None and reason is not None: code = 1000 # "normal closure" status code if code is None: close_data = b"" else: close_data = struct.pack(">H", code) if reason is not None: close_data += utf8(reason) try: self._write_frame(True, 0x8, close_data) except StreamClosedError: self._abort() self.server_terminated = True if self.client_terminated: if self._waiting is not None: self._waiting = None elif self._waiting is None: # Give the client a few seconds to complete a clean shutdown, # otherwise just close the connection. self._waiting = + 5, self._abort ) if self.ping_callback: self.ping_callback.stop() self.ping_callback = None def is_closing(self) -> bool: """Return ``True`` if this connection is closing. The connection is considered closing if either side has initiated its closing handshake or if the stream has been shut down uncleanly. """ return or self.client_terminated or self.server_terminated @property def ping_interval(self) -> Optional[float]: interval = self.params.ping_interval if interval is not None: return interval return 0 @property def ping_timeout(self) -> Optional[float]: timeout = self.params.ping_timeout if timeout is not None: return timeout assert self.ping_interval is not None return max(3 * self.ping_interval, 30) def start_pinging(self) -> None: """Start sending periodic pings to keep the connection alive""" assert self.ping_interval is not None if self.ping_interval > 0: self.last_ping = self.last_pong = IOLoop.current().time() self.ping_callback = PeriodicCallback( self.periodic_ping, self.ping_interval * 1000 ) self.ping_callback.start() def periodic_ping(self) -> None: """Send a ping to keep the websocket alive Called periodically if the websocket_ping_interval is set and non-zero. """ if self.is_closing() and self.ping_callback is not None: self.ping_callback.stop() return # Check for timeout on pong. Make sure that we really have # sent a recent ping in case the machine with both server and # client has been suspended since the last ping. now = IOLoop.current().time() since_last_pong = now - self.last_pong since_last_ping = now - self.last_ping assert self.ping_interval is not None assert self.ping_timeout is not None if ( since_last_ping < 2 * self.ping_interval and since_last_pong > self.ping_timeout ): self.close() return self.write_ping(b"") self.last_ping = now def set_nodelay(self, x: bool) -> None:
[docs]class WebSocketClientConnection(simple_httpclient._HTTPConnection): """WebSocket client connection. This class should not be instantiated directly; use the `websocket_connect` function instead. """ protocol = None # type: WebSocketProtocol def __init__( self, request: httpclient.HTTPRequest, on_message_callback: Optional[Callable[[Union[None, str, bytes]], None]] = None, compression_options: Optional[Dict[str, Any]] = None, ping_interval: Optional[float] = None, ping_timeout: Optional[float] = None, max_message_size: int = _default_max_message_size, subprotocols: Optional[List[str]] = None, resolver: Optional[Resolver] = None, ) -> None: self.connect_future = Future() # type: Future[WebSocketClientConnection] self.read_queue = Queue(1) # type: Queue[Union[None, str, bytes]] self.key = base64.b64encode(os.urandom(16)) self._on_message_callback = on_message_callback self.close_code = None # type: Optional[int] self.close_reason = None # type: Optional[str] self.params = _WebSocketParams( ping_interval=ping_interval, ping_timeout=ping_timeout, max_message_size=max_message_size, compression_options=compression_options, ) scheme, sep, rest = request.url.partition(":") scheme = {"ws": "http", "wss": "https"}[scheme] request.url = scheme + sep + rest request.headers.update( { "Upgrade": "websocket", "Connection": "Upgrade", "Sec-WebSocket-Key": self.key, "Sec-WebSocket-Version": "13", } ) if subprotocols is not None: request.headers["Sec-WebSocket-Protocol"] = ",".join(subprotocols) if compression_options is not None: # Always offer to let the server set our max_wbits (and even though # we don't offer it, we will accept a client_no_context_takeover # from the server). # TODO: set server parameters for deflate extension # if requested in self.compression_options. request.headers[ "Sec-WebSocket-Extensions" ] = "permessage-deflate; client_max_window_bits" # Websocket connection is currently unable to follow redirects request.follow_redirects = False self.tcp_client = TCPClient(resolver=resolver) super().__init__( None, request, lambda: None, self._on_http_response, 104857600, self.tcp_client, 65536, 104857600, ) def __del__(self) -> None: if self.protocol is not None: # Unclosed client connections can sometimes log "task was destroyed but # was pending" warnings if shutdown strikes at the wrong time (such as # while a ping is being processed due to ping_interval). Log our own # warning to make it a little more deterministic (although it's still # dependent on GC timing). warnings.warn("Unclosed WebSocketClientConnection", ResourceWarning)
[docs] def close(self, code: Optional[int] = None, reason: Optional[str] = None) -> None: """Closes the websocket connection. ``code`` and ``reason`` are documented under `WebSocketHandler.close`. .. versionadded:: 3.2 .. versionchanged:: 4.0 Added the ``code`` and ``reason`` arguments. """ if self.protocol is not None: self.protocol.close(code, reason) self.protocol = None # type: ignore
def on_connection_close(self) -> None: if not self.connect_future.done(): self.connect_future.set_exception(StreamClosedError()) self._on_message(None) self.tcp_client.close() super().on_connection_close() def on_ws_connection_close( self, close_code: Optional[int] = None, close_reason: Optional[str] = None ) -> None: self.close_code = close_code self.close_reason = close_reason self.on_connection_close() def _on_http_response(self, response: httpclient.HTTPResponse) -> None: if not self.connect_future.done(): if response.error: self.connect_future.set_exception(response.error) else: self.connect_future.set_exception( WebSocketError("Non-websocket response") ) async def headers_received( self, start_line: Union[httputil.RequestStartLine, httputil.ResponseStartLine], headers: httputil.HTTPHeaders, ) -> None: assert isinstance(start_line, httputil.ResponseStartLine) if start_line.code != 101: await super().headers_received(start_line, headers) return if self._timeout is not None: self.io_loop.remove_timeout(self._timeout) self._timeout = None self.headers = headers self.protocol = self.get_websocket_protocol() self.protocol._process_server_headers(self.key, self.headers) = self.connection.detach() IOLoop.current().add_callback(self.protocol._receive_frame_loop) self.protocol.start_pinging() # Once we've taken over the connection, clear the final callback # we set on the http request. This deactivates the error handling # in simple_httpclient that would otherwise interfere with our # ability to see exceptions. self.final_callback = None # type: ignore future_set_result_unless_cancelled(self.connect_future, self)
[docs] def write_message( self, message: Union[str, bytes, Dict[str, Any]], binary: bool = False ) -> "Future[None]": """Sends a message to the WebSocket server. If the stream is closed, raises `WebSocketClosedError`. Returns a `.Future` which can be used for flow control. .. versionchanged:: 5.0 Exception raised on a closed stream changed from `.StreamClosedError` to `WebSocketClosedError`. """ if self.protocol is None: raise WebSocketClosedError("Client connection has been closed") return self.protocol.write_message(message, binary=binary)
[docs] def read_message( self, callback: Optional[Callable[["Future[Union[None, str, bytes]]"], None]] = None, ) -> Awaitable[Union[None, str, bytes]]: """Reads a message from the WebSocket server. If on_message_callback was specified at WebSocket initialization, this function will never return messages Returns a future whose result is the message, or None if the connection is closed. If a callback argument is given it will be called with the future when it is ready. """ awaitable = self.read_queue.get() if callback is not None: self.io_loop.add_future(asyncio.ensure_future(awaitable), callback) return awaitable
def on_message(self, message: Union[str, bytes]) -> Optional[Awaitable[None]]: return self._on_message(message) def _on_message( self, message: Union[None, str, bytes] ) -> Optional[Awaitable[None]]: if self._on_message_callback: self._on_message_callback(message) return None else: return self.read_queue.put(message)
[docs] def ping(self, data: bytes = b"") -> None: """Send ping frame to the remote end. The data argument allows a small amount of data (up to 125 bytes) to be sent as a part of the ping message. Note that not all websocket implementations expose this data to applications. Consider using the ``ping_interval`` argument to `websocket_connect` instead of sending pings manually. .. versionadded:: 5.1 """ data = utf8(data) if self.protocol is None: raise WebSocketClosedError() self.protocol.write_ping(data)
def on_pong(self, data: bytes) -> None: pass def on_ping(self, data: bytes) -> None: pass def get_websocket_protocol(self) -> WebSocketProtocol: return WebSocketProtocol13(self, mask_outgoing=True, params=self.params) @property def selected_subprotocol(self) -> Optional[str]: """The subprotocol selected by the server. .. versionadded:: 5.1 """ return self.protocol.selected_subprotocol def log_exception( self, typ: "Optional[Type[BaseException]]", value: Optional[BaseException], tb: Optional[TracebackType], ) -> None: assert typ is not None assert value is not None app_log.error("Uncaught exception %s", value, exc_info=(typ, value, tb))
[docs]def websocket_connect( url: Union[str, httpclient.HTTPRequest], callback: Optional[Callable[["Future[WebSocketClientConnection]"], None]] = None, connect_timeout: Optional[float] = None, on_message_callback: Optional[Callable[[Union[None, str, bytes]], None]] = None, compression_options: Optional[Dict[str, Any]] = None, ping_interval: Optional[float] = None, ping_timeout: Optional[float] = None, max_message_size: int = _default_max_message_size, subprotocols: Optional[List[str]] = None, resolver: Optional[Resolver] = None, ) -> "Awaitable[WebSocketClientConnection]": """Client-side websocket support. Takes a url and returns a Future whose result is a `WebSocketClientConnection`. ``compression_options`` is interpreted in the same way as the return value of `.WebSocketHandler.get_compression_options`. The connection supports two styles of operation. In the coroutine style, the application typically calls `~.WebSocketClientConnection.read_message` in a loop:: conn = yield websocket_connect(url) while True: msg = yield conn.read_message() if msg is None: break # Do something with msg In the callback style, pass an ``on_message_callback`` to ``websocket_connect``. In both styles, a message of ``None`` indicates that the connection has been closed. ``subprotocols`` may be a list of strings specifying proposed subprotocols. The selected protocol may be found on the ``selected_subprotocol`` attribute of the connection object when the connection is complete. .. versionchanged:: 3.2 Also accepts ``HTTPRequest`` objects in place of urls. .. versionchanged:: 4.1 Added ``compression_options`` and ``on_message_callback``. .. versionchanged:: 4.5 Added the ``ping_interval``, ``ping_timeout``, and ``max_message_size`` arguments, which have the same meaning as in `WebSocketHandler`. .. versionchanged:: 5.0 The ``io_loop`` argument (deprecated since version 4.1) has been removed. .. versionchanged:: 5.1 Added the ``subprotocols`` argument. .. versionchanged:: 6.3 Added the ``resolver`` argument. """ if isinstance(url, httpclient.HTTPRequest): assert connect_timeout is None request = url # Copy and convert the headers dict/object (see comments in # AsyncHTTPClient.fetch) request.headers = httputil.HTTPHeaders(request.headers) else: request = httpclient.HTTPRequest(url, connect_timeout=connect_timeout) request = cast( httpclient.HTTPRequest, httpclient._RequestProxy(request, httpclient.HTTPRequest._DEFAULTS), ) conn = WebSocketClientConnection( request, on_message_callback=on_message_callback, compression_options=compression_options, ping_interval=ping_interval, ping_timeout=ping_timeout, max_message_size=max_message_size, subprotocols=subprotocols, resolver=resolver, ) if callback is not None: IOLoop.current().add_future(conn.connect_future, callback) return conn.connect_future