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,
although older versions that do not support WebSockets are still in use
(refer to for details).

This module implements the final version of the WebSocket protocol as
defined in `RFC 6455 <>`_.  Certain
browser versions (notably Safari 5.x) implemented an earlier draft of
the protocol (known as "draft 76") and are not compatible with this module.

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

from __future__ import absolute_import, division, print_function, with_statement
# Author: Jacob Kristhammar, 2010

import base64
import collections
import hashlib
import os
import struct
import tornado.escape
import tornado.web
import zlib

from tornado.concurrent import TracebackFuture
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
from tornado.log import gen_log, app_log
from tornado import simple_httpclient
from tornado.tcpclient import TCPClient
from tornado.util import _websocket_mask, PY3

if PY3:
    from urllib.parse import urlparse  # py2
    xrange = range
    from urlparse import urlparse  # py3

class WebSocketError(Exception):

[docs]class WebSocketClosedError(WebSocketError): """Raised by operations on a closed connection. .. versionadded:: 3.2 """ pass
[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. 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. """ def __init__(self, application, request, **kwargs): super(WebSocketHandler, self).__init__(application, request, **kwargs) self.ws_connection = None self.close_code = None self.close_reason = None = None self._on_close_called = False @tornado.web.asynchronous def get(self, *args, **kwargs): 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.request.connection.detach() self.ws_connection = self.get_websocket_protocol() if self.ws_connection: self.ws_connection.accept_connection() else: if not "HTTP/1.1 426 Upgrade Required\r\n" "Sec-WebSocket-Version: 7, 8, 13\r\n\r\n")) stream = None @property def ping_interval(self): """The interval for websocket keep-alive pings. Set ws_ping_interval = 0 to disable pings. """ return self.settings.get('websocket_ping_interval', None) @property def ping_timeout(self): """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)
[docs] def write_message(self, message, binary=False): """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`. .. 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. """ if self.ws_connection is None: 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): """Invoked when a new WebSocket requests specific subprotocols. ``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. """ return None
[docs] def get_compression_options(self): """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 memory and CPU usage of the compression, but no such options are currently implemented. .. versionadded:: 4.1 """ return None
[docs] def open(self, *args, **kwargs): """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`. """ pass
[docs] def on_message(self, message): """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): """Send ping frame to the remote end.""" if self.ws_connection is None: raise WebSocketClosedError() self.ws_connection.write_ping(data)
[docs] def on_pong(self, data): """Invoked when the response to a ping frame is received.""" pass
def on_ping(self, data): """Invoked when the a ping frame is received.""" pass
[docs] def on_close(self): """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=None, reason=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): """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): """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 """
def on_connection_close(self): 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() def send_error(self, *args, **kwargs): if is None: super(WebSocketHandler, self).send_error(*args, **kwargs) else: # If we get an uncaught exception during the handshake, # we have no choice but to abruptly close the connection. # TODO: for uncaught exceptions after the handshake, # we can close the connection more gracefully. def get_websocket_protocol(self): websocket_version = self.request.headers.get("Sec-WebSocket-Version") if websocket_version in ("7", "8", "13"): return WebSocketProtocol13( self, compression_options=self.get_compression_options())
def _wrap_method(method): def _disallow_for_websocket(self, *args, **kwargs): if is None: method(self, *args, **kwargs) else: raise RuntimeError("Method not supported for Web Sockets") return _disallow_for_websocket for method in ["write", "redirect", "set_header", "set_cookie", "set_status", "flush", "finish"]: setattr(WebSocketHandler, method, _wrap_method(getattr(WebSocketHandler, method))) class WebSocketProtocol(object): """Base class for WebSocket protocol versions. """ def __init__(self, handler): self.handler = handler self.request = handler.request = self.client_terminated = False self.server_terminated = False def _run_callback(self, callback, *args, **kwargs): """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: app_log.error("Uncaught exception in %s", getattr(self.request, 'path', None), exc_info=True) self._abort() else: if result is not None:, lambda f: f.result()) return result def on_connection_close(self): self._abort() def _abort(self): """Instantly aborts the WebSocket connection by closing the socket""" self.client_terminated = True self.server_terminated = True # forcibly tear down the connection self.close() # let the subclass cleanup class _PerMessageDeflateCompressor(object): def __init__(self, persistent, max_wbits): 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 persistent: self._compressor = self._create_compressor() else: self._compressor = None def _create_compressor(self): return zlib.compressobj(tornado.web.GZipContentEncoding.GZIP_LEVEL, zlib.DEFLATED, -self._max_wbits) def compress(self, data): 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, max_wbits): 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() else: self._decompressor = None def _create_decompressor(self): return zlib.decompressobj(-self._max_wbits) def decompress(self, data): decompressor = self._decompressor or self._create_decompressor() return decompressor.decompress(data + b'\x00\x00\xff\xff') 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 def __init__(self, handler, mask_outgoing=False, compression_options=None): WebSocketProtocol.__init__(self, handler) self.mask_outgoing = mask_outgoing self._final_frame = False self._frame_opcode = None self._masked_frame = None self._frame_mask = None self._frame_length = None self._fragmented_message_buffer = None self._fragmented_message_opcode = None self._waiting = None self._compression_options = compression_options self._decompressor = None self._compressor = None self._frame_compressed = None # 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 self.last_ping = 0 self.last_pong = 0 def accept_connection(self): try: self._handle_websocket_headers() self._accept_connection() except ValueError: gen_log.debug("Malformed WebSocket request received", exc_info=True) self._abort() return def _handle_websocket_headers(self): """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: self.request.headers.get(f), fields)): raise ValueError("Missing/Invalid WebSocket headers") @staticmethod def compute_accept_value(key): """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): return WebSocketProtocol13.compute_accept_value( self.request.headers.get("Sec-Websocket-Key")) def _accept_connection(self): subprotocol_header = '' subprotocols = self.request.headers.get("Sec-WebSocket-Protocol", '') subprotocols = [s.strip() for s in subprotocols.split(',')] if subprotocols: selected = self.handler.select_subprotocol(subprotocols) if selected: assert selected in subprotocols subprotocol_header = ("Sec-WebSocket-Protocol: %s\r\n" % selected) extension_header = '' extensions = self._parse_extensions_header(self.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]) 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'] extension_header = ('Sec-WebSocket-Extensions: %s\r\n' % httputil._encode_header( 'permessage-deflate', ext[1])) break if self._abort() return "HTTP/1.1 101 Switching Protocols\r\n" "Upgrade: websocket\r\n" "Connection: Upgrade\r\n" "Sec-WebSocket-Accept: %s\r\n" "%s%s" "\r\n" % (self._challenge_response(), subprotocol_header, extension_header))) self.start_pinging() self._run_callback(, *self.handler.open_args, **self.handler.open_kwargs) self._receive_frame() def _parse_extensions_header(self, headers): 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, headers): """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) def _get_compressor_options(self, side, agreed_parameters): """Converts a websocket agreed_parameters set to keyword arguments for our compressor objects. """ options = dict( persistent=(side + '_no_context_takeover') not in agreed_parameters) 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) return options def _create_compressors(self, side, agreed_parameters): # 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)) self._decompressor = _PerMessageDeflateDecompressor( **self._get_compressor_options(other_side, agreed_parameters)) def _write_frame(self, fin, opcode, data, flags=0): if fin: finbit = self.FIN else: finbit = 0 frame = struct.pack("B", finbit | opcode | flags) l = len(data) if self.mask_outgoing: mask_bit = 0x80 else: mask_bit = 0 if l < 126: frame += struct.pack("B", l | mask_bit) elif l <= 0xFFFF: frame += struct.pack("!BH", 126 | mask_bit, l) else: frame += struct.pack("!BQ", 127 | mask_bit, l) if self.mask_outgoing: mask = os.urandom(4) data = mask + _websocket_mask(mask, data) frame += data self._wire_bytes_out += len(frame) try: return except StreamClosedError: self._abort() def write_message(self, message, binary=False): """Sends the given message to the client of this Web Socket.""" if binary: opcode = 0x2 else: opcode = 0x1 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 return self._write_frame(True, opcode, message, flags=flags) def write_ping(self, data): """Send ping frame.""" assert isinstance(data, bytes) self._write_frame(True, 0x9, data) def _receive_frame(self): try:, self._on_frame_start) except StreamClosedError: self._abort() def _on_frame_start(self, data): self._wire_bytes_in += len(data) header, payloadlen = struct.unpack("BB", data) self._final_frame = header & self.FIN reserved_bits = header & self.RSV_MASK self._frame_opcode = header & self.OPCODE_MASK self._frame_opcode_is_control = self._frame_opcode & 0x8 if self._decompressor is not None and self._frame_opcode != 0: 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 self._masked_frame = bool(payloadlen & 0x80) payloadlen = payloadlen & 0x7f if self._frame_opcode_is_control and payloadlen >= 126: # control frames must have payload < 126 self._abort() return try: if payloadlen < 126: self._frame_length = payloadlen if self._masked_frame:, self._on_masking_key) else:, self._on_frame_data) elif payloadlen == 126:, self._on_frame_length_16) elif payloadlen == 127:, self._on_frame_length_64) except StreamClosedError: self._abort() def _on_frame_length_16(self, data): self._wire_bytes_in += len(data) self._frame_length = struct.unpack("!H", data)[0] try: if self._masked_frame:, self._on_masking_key) else:, self._on_frame_data) except StreamClosedError: self._abort() def _on_frame_length_64(self, data): self._wire_bytes_in += len(data) self._frame_length = struct.unpack("!Q", data)[0] try: if self._masked_frame:, self._on_masking_key) else:, self._on_frame_data) except StreamClosedError: self._abort() def _on_masking_key(self, data): self._wire_bytes_in += len(data) self._frame_mask = data try:, self._on_masked_frame_data) except StreamClosedError: self._abort() def _on_masked_frame_data(self, data): # Don't touch _wire_bytes_in; we'll do it in _on_frame_data. self._on_frame_data(_websocket_mask(self._frame_mask, data)) def _on_frame_data(self, data): handled_future = None self._wire_bytes_in += len(data) if self._frame_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 self._final_frame: # control frames must not be fragmented self._abort() return opcode = self._frame_opcode elif self._frame_opcode == 0: # continuation frame if self._fragmented_message_buffer is None: # nothing to continue self._abort() return self._fragmented_message_buffer += data if self._final_frame: opcode = self._fragmented_message_opcode data = 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 self._final_frame: opcode = self._frame_opcode else: self._fragmented_message_opcode = self._frame_opcode self._fragmented_message_buffer = data if self._final_frame: handled_future = self._handle_message(opcode, data) if not self.client_terminated: if handled_future: # on_message is a coroutine, process more frames once it's done. gen.convert_yielded(handled_future).add_done_callback( lambda future: self._receive_frame()) else: self._receive_frame() def _handle_message(self, opcode, data): """Execute on_message, returning its Future if it is a coroutine.""" if self.client_terminated: return if self._frame_compressed: data = self._decompressor.decompress(data) if opcode == 0x1: # UTF-8 data self._message_bytes_in += len(data) try: decoded = data.decode("utf-8") except UnicodeDecodeError: self._abort() return 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.handler.close_code = struct.unpack('>H', data[:2])[0] if len(data) > 2: self.handler.close_reason = to_unicode(data[2:]) # Echo the received close code, if any (RFC 6455 section 5.5.1). self.close(self.handler.close_code) elif opcode == 0x9: # Ping self._write_frame(True, 0xA, data) 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() def close(self, code=None, reason=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) self._write_frame(True, 0x8, close_data) 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) @property def ping_interval(self): interval = self.handler.ping_interval if interval is not None: return interval return 0 @property def ping_timeout(self): timeout = self.handler.ping_timeout if timeout is not None: return timeout return max(3 * self.ping_interval, 30) def start_pinging(self): """Start sending periodic pings to keep the connection alive""" 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): """Send a ping to keep the websocket alive Called periodically if the websocket_ping_interval is set and non-zero. """ if 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 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
[docs]class WebSocketClientConnection(simple_httpclient._HTTPConnection): """WebSocket client connection. This class should not be instantiated directly; use the `websocket_connect` function instead. """ def __init__(self, io_loop, request, on_message_callback=None, compression_options=None, ping_interval=None, ping_timeout=None): self.compression_options = compression_options self.connect_future = TracebackFuture() self.protocol = None self.read_future = None self.read_queue = collections.deque() self.key = base64.b64encode(os.urandom(16)) self._on_message_callback = on_message_callback self.close_code = self.close_reason = None self.ping_interval = ping_interval self.ping_timeout = ping_timeout 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 self.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') self.tcp_client = TCPClient(io_loop=io_loop) super(WebSocketClientConnection, self).__init__( io_loop, None, request, lambda: None, self._on_http_response, 104857600, self.tcp_client, 65536, 104857600)
[docs] def close(self, code=None, reason=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
def on_connection_close(self): if not self.connect_future.done(): self.connect_future.set_exception(StreamClosedError()) self.on_message(None) self.tcp_client.close() super(WebSocketClientConnection, self).on_connection_close() def _on_http_response(self, response): 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")) def headers_received(self, start_line, headers): if start_line.code != 101: return super(WebSocketClientConnection, self).headers_received( start_line, headers) self.headers = headers self.protocol = self.get_websocket_protocol() self.protocol._process_server_headers(self.key, self.headers) self.protocol.start_pinging() self.protocol._receive_frame() if self._timeout is not None: self.io_loop.remove_timeout(self._timeout) self._timeout = None = self.connection.detach() # 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 self.connect_future.set_result(self)
[docs] def write_message(self, message, binary=False): """Sends a message to the WebSocket server.""" return self.protocol.write_message(message, binary)
[docs] def read_message(self, callback=None): """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. """ assert self.read_future is None future = TracebackFuture() if self.read_queue: future.set_result(self.read_queue.popleft()) else: self.read_future = future if callback is not None: self.io_loop.add_future(future, callback) return future
def on_message(self, message): if self._on_message_callback: self._on_message_callback(message) elif self.read_future is not None: self.read_future.set_result(message) self.read_future = None else: self.read_queue.append(message) def on_pong(self, data): pass def on_ping(self, data): pass def get_websocket_protocol(self): return WebSocketProtocol13(self, mask_outgoing=True, compression_options=self.compression_options)
[docs]def websocket_connect(url, io_loop=None, callback=None, connect_timeout=None, on_message_callback=None, compression_options=None, ping_interval=None, ping_timeout=None): """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. .. versionchanged:: 3.2 Also accepts ``HTTPRequest`` objects in place of urls. .. versionchanged:: 4.1 Added ``compression_options`` and ``on_message_callback``. The ``io_loop`` argument is deprecated. """ if io_loop is None: io_loop = IOLoop.current() 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 = httpclient._RequestProxy( request, httpclient.HTTPRequest._DEFAULTS) conn = WebSocketClientConnection(io_loop, request, on_message_callback=on_message_callback, compression_options=compression_options, ping_interval=ping_interval, ping_timeout=ping_timeout) if callback is not None: io_loop.add_future(conn.connect_future, callback) return conn.connect_future