Source code for ws4py.websocket

# -*- coding: utf-8 -*-
import logging
import socket
import ssl
import time
import threading
import types
import errno

    from OpenSSL.SSL import Error as pyOpenSSLError
except ImportError:
    class pyOpenSSLError(Exception):

from ws4py import WS_KEY, WS_VERSION
from ws4py.exc import HandshakeError, StreamClosed
from ws4py.streaming import Stream
from ws4py.messaging import Message, PingControlMessage,\
from ws4py.compat import basestring, unicode


logger = logging.getLogger('ws4py')

__all__ = ['WebSocket', 'EchoWebSocket', 'Heartbeat']

[docs]class Heartbeat(threading.Thread): def __init__(self, websocket, frequency=2.0): """ Runs at a periodic interval specified by `frequency` by sending an unsolicitated pong message to the connected peer. If the message fails to be sent and a socket error is raised, we close the websocket socket automatically, triggering the `closed` handler. """ threading.Thread.__init__(self) self.websocket = websocket self.frequency = frequency def __enter__(self): if self.frequency: self.start() return self def __exit__(self, exc_type, exc_value, exc_tb): self.stop()
[docs] def stop(self):
self.running = False
[docs] def run(self): self.running = True while self.running: time.sleep(self.frequency) if self.websocket.terminated: break try: self.websocket.send(PongControlMessage(data='beep')) except socket.error:"Heartbeat failed") self.websocket.server_terminated = True self.websocket.close_connection()
[docs]class WebSocket(object): """ Represents a websocket endpoint and provides a high level interface to drive the endpoint. """ def __init__(self, sock, protocols=None, extensions=None, environ=None, heartbeat_freq=None): """ The ``sock`` is an opened connection resulting from the websocket handshake. If ``protocols`` is provided, it is a list of protocols negotiated during the handshake as is ``extensions``. If ``environ`` is provided, it is a copy of the WSGI environ dictionnary from the underlying WSGI server. """ = Stream(always_mask=False) """ Underlying websocket stream that performs the websocket parsing to high level objects. By default this stream never masks its messages. Clients using this class should set the ``stream.always_mask`` fields to ``True`` and ``stream.expect_masking`` fields to ``False``. """ self.protocols = protocols """ List of protocols supported by this endpoint. Unused for now. """ self.extensions = extensions """ List of extensions supported by this endpoint. Unused for now. """ self.sock = sock """ Underlying connection. """ self._is_secure = hasattr(sock, '_ssl') or hasattr(sock, '_sslobj') """ Tell us if the socket is secure or not. """ self.client_terminated = False """ Indicates if the client has been marked as terminated. """ self.server_terminated = False """ Indicates if the server has been marked as terminated. """ self.reading_buffer_size = DEFAULT_READING_SIZE """ Current connection reading buffer size. """ self.environ = environ """ WSGI environ dictionary. """ self.heartbeat_freq = heartbeat_freq """ At which interval the heartbeat will be running. Set this to `0` or `None` to disable it entirely. """ "Internal buffer to get around SSL problems" self.buf = b'' self._local_address = None self._peer_address = None @property def local_address(self): """ Local endpoint address as a tuple """ if not self._local_address: self._local_address = self.sock.getsockname() if len(self._local_address) == 4: self._local_address = self._local_address[:2] return self._local_address @property def peer_address(self): """ Peer endpoint address as a tuple """ if not self._peer_address: self._peer_address = self.sock.getpeername() if len(self._peer_address) == 4: self._peer_address = self._peer_address[:2] return self._peer_address
[docs] def opened(self): """ Called by the server when the upgrade handshake has succeeded. """
[docs] def close(self, code=1000, reason=''): """ Call this method to initiate the websocket connection closing by sending a close frame to the connected peer. The ``code`` is the status code representing the termination's reason. Once this method is called, the ``server_terminated`` attribute is set. Calling this method several times is safe as the closing frame will be sent only the first time. .. seealso:: Defined Status Codes """ if not self.server_terminated: self.server_terminated = True try: self._write(, reason=reason).single( except Exception as ex:
logger.error("Error when terminating the connection: %s", str(ex))
[docs] def closed(self, code, reason=None): """ Called when the websocket stream and connection are finally closed. The provided ``code`` is status set by the other point and ``reason`` is a human readable message. .. seealso:: Defined Status Codes """
pass @property def terminated(self): """ Returns ``True`` if both the client and server have been marked as terminated. """ return self.client_terminated is True and self.server_terminated is True @property def connection(self): return self.sock
[docs] def close_connection(self): """ Shutdowns then closes the underlying connection. """ if self.sock: try: self.sock.shutdown(socket.SHUT_RDWR) self.sock.close() except: pass finally:
self.sock = None
[docs] def ping(self, message): """ Send a ping message to the remote peer. The given `message` must be a unicode string. """
[docs] def ponged(self, pong): """ Pong message, as a :class:`messaging.PongControlMessage` instance, received on the stream. """
[docs] def received_message(self, message): """ Called whenever a complete ``message``, binary or text, is received and ready for application's processing. The passed message is an instance of :class:`messaging.TextMessage` or :class:`messaging.BinaryMessage`. .. note:: You should override this method in your subclass. """
[docs] def unhandled_error(self, error): """ Called whenever a socket, or an OS, error is trapped by ws4py but not managed by it. The given error is an instance of `socket.error` or `OSError`. Note however that application exceptions will not go through this handler. Instead, do make sure you protect your code appropriately in `received_message` or `send`. The default behaviour of this handler is to log the error with a message. """
logger.exception("Failed to receive data") def _write(self, b): """ Trying to prevent a write operation on an already closed websocket stream. This cannot be bullet proof but hopefully will catch almost all use cases. """ if self.terminated or self.sock is None: raise RuntimeError("Cannot send on a terminated websocket") self.sock.sendall(b)
[docs] def send(self, payload, binary=False): """ Sends the given ``payload`` out. If ``payload`` is some bytes or a bytearray, then it is sent as a single message not fragmented. If ``payload`` is a generator, each chunk is sent as part of fragmented message. If ``binary`` is set, handles the payload as a binary message. """ message_sender = if binary else if isinstance(payload, basestring) or isinstance(payload, bytearray): m = message_sender(payload).single( self._write(m) elif isinstance(payload, Message): data = payload.single( self._write(data) elif type(payload) == types.GeneratorType: bytes = next(payload) first = True for chunk in payload: self._write(message_sender(bytes).fragment(first=first, bytes = chunk first = False self._write(message_sender(bytes).fragment(first=first, last=True, else:
raise ValueError("Unsupported type '%s' passed to send()" % type(payload)) def _get_from_pending(self): """ The SSL socket object provides the same interface as the socket interface but behaves differently. When data is sent over a SSL connection more data may be read than was requested from by the ws4py websocket object. In that case, the data may have been indeed read from the underlying real socket, but not read by the application which will expect another trigger from the manager's polling mechanism as if more data was still on the wire. This will happen only when new data is sent by the other peer which means there will be some delay before the initial read data is handled by the application. Due to this, we have to rely on a non-public method to query the internal SSL socket buffer if it has indeed more data pending in its buffer. Now, some people in the Python community `discourage <>`_ this usage of the ``pending()`` method because it's not the right way of dealing with such use case. They advise `this approach <>`_ instead. Unfortunately, this applies only if the application can directly control the poller which is not the case with the WebSocket abstraction here. We therefore rely on this `technic <>`_ which seems to be valid anyway. This is a bit of a shame because we have to process more data than what wanted initially. """ data = b"" pending = self.sock.pending() while pending: data += self.sock.recv(pending) pending = self.sock.pending() return data
[docs] def once(self): """ Performs the operation of reading from the underlying connection in order to feed the stream of bytes. Because this needs to support SSL sockets, we must always read as much as might be in the socket at any given time, however process expects to have itself called with only a certain number of bytes at a time. That number is found in self.reading_buffer_size, so we read everything into our own buffer, and then from there feed self.process. Then the stream indicates whatever size must be read from the connection since it knows the frame payload length. It returns `False` if an error occurred at the socket level or during the bytes processing. Otherwise, it returns `True`. """ if self.terminated: logger.debug("WebSocket is already terminated") return False try: b = b'' if self._is_secure: b = self._get_from_pending() if not b and not self.buf: b = self.sock.recv(self.reading_buffer_size) if not b and not self.buf: return False self.buf += b except (socket.error, OSError, pyOpenSSLError) as e: if hasattr(e, "errno") and e.errno == errno.EINTR: pass else: self.unhandled_error(e) return False else: # process as much as we can # the process will stop either if there is no buffer left # or if the stream is closed # only pass the requested number of bytes, leave the rest in the buffer requested = self.reading_buffer_size if not self.process(self.buf[:requested]): return False self.buf = self.buf[requested:]
return True
[docs] def terminate(self): """ Completes the websocket by calling the `closed` method either using the received closing code and reason, or when none was received, using the special `1006` code. Finally close the underlying connection for good and cleanup resources by unsetting the `environ` and `stream` attributes. """ s = try: if s.closing is None: self.closed(1006, "Going away") else: self.closed(s.closing.code, s.closing.reason) finally: self.client_terminated = self.server_terminated = True self.close_connection() # Cleaning up resources s._cleanup() = None
self.environ = None
[docs] def process(self, bytes): """ Takes some bytes and process them through the internal stream's parser. If a message of any kind is found, performs one of these actions: * A closing message will initiate the closing handshake * Errors will initiate a closing handshake * A message will be passed to the ``received_message`` method * Pings will see pongs be sent automatically * Pongs will be passed to the ``ponged`` method The process should be terminated when this method returns ``False``. """ s = if not bytes and self.reading_buffer_size > 0: return False self.reading_buffer_size = s.parser.send(bytes) or DEFAULT_READING_SIZE if s.closing is not None: logger.debug("Closing message received (%d) '%s'" % (s.closing.code, s.closing.reason)) if not self.server_terminated: self.close(s.closing.code, s.closing.reason) else: self.client_terminated = True return False if s.errors: for error in s.errors: logger.debug("Error message received (%d) '%s'" % (error.code, error.reason)) self.close(error.code, error.reason) s.errors = [] return False if s.has_message: self.received_message(s.message) if s.message is not None: = None s.message = None return True if s.pings: for ping in s.pings: self._write(s.pong( s.pings = [] if s.pongs: for pong in s.pongs: self.ponged(pong) s.pongs = []
return True
[docs] def run(self): """ Performs the operation of reading from the underlying connection in order to feed the stream of bytes. We start with a small size of two bytes to be read from the connection so that we can quickly parse an incoming frame header. Then the stream indicates whatever size must be read from the connection since it knows the frame payload length. Note that we perform some automatic opererations: * On a closing message, we respond with a closing message and finally close the connection * We respond to pings with pong messages. * Whenever an error is raised by the stream parsing, we initiate the closing of the connection with the appropiate error code. This method is blocking and should likely be run in a thread. """ self.sock.setblocking(True) with Heartbeat(self, frequency=self.heartbeat_freq): s = try: self.opened() while not self.terminated: if not self.once(): break finally:
[docs]class EchoWebSocket(WebSocket):
[docs] def received_message(self, message): """ Automatically sends back the provided ``message`` to its originating endpoint. """
self.send(, message.is_binary)