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# -*- coding: utf-8 -*-
import logging
import socket
import ssl
import time
import threading
import types
import errno
try:
from OpenSSL.SSL import Error as pyOpenSSLError
except ImportError:
class pyOpenSSLError(Exception):
pass
from ws4py import WS_KEY, WS_VERSION
from ws4py.exc import HandshakeError, StreamClosed
from ws4py.streaming import Stream
from ws4py.messaging import Message, PingControlMessage,\
PongControlMessage
from ws4py.compat import basestring, unicode
DEFAULT_READING_SIZE = 2
logger = logging.getLogger('ws4py')
__all__ = ['WebSocket', 'EchoWebSocket', 'Heartbeat']
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()
def stop(self):
self.running = False
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:
logger.info("Heartbeat failed")
self.websocket.server_terminated = True
self.websocket.close_connection()
break
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.
"""
self.stream = 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
def opened(self):
"""
Called by the server when the upgrade handshake
has succeeded.
"""
pass
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 http://tools.ietf.org/html/rfc6455#section-7.4.1
"""
if not self.server_terminated:
self.server_terminated = True
try:
self._write(self.stream.close(code=code, reason=reason).single(mask=self.stream.always_mask))
except Exception as ex:
logger.error("Error when terminating the connection: %s", str(ex))
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 http://tools.ietf.org/html/rfc6455#section-7.4.1
"""
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
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
def ping(self, message):
"""
Send a ping message to the remote peer.
The given `message` must be a unicode string.
"""
self.send(PingControlMessage(message))
def ponged(self, pong):
"""
Pong message, as a :class:`messaging.PongControlMessage` instance,
received on the stream.
"""
pass
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.
"""
pass
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)
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 = self.stream.binary_message if binary else self.stream.text_message
if isinstance(payload, basestring) or isinstance(payload, bytearray):
m = message_sender(payload).single(mask=self.stream.always_mask)
self._write(m)
elif isinstance(payload, Message):
data = payload.single(mask=self.stream.always_mask)
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, mask=self.stream.always_mask))
bytes = chunk
first = False
self._write(message_sender(bytes).fragment(first=first, last=True, mask=self.stream.always_mask))
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 <https://bugs.python.org/issue21430>`_
this usage of the ``pending()`` method because it's not
the right way of dealing with such use case. They advise
`this approach <https://docs.python.org/dev/library/ssl.html#notes-on-non-blocking-sockets>`_
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 <http://stackoverflow.com/questions/3187565/select-and-ssl-in-python>`_
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
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 = self.sock.recv(self.reading_buffer_size)
if self._is_secure:
b += self._get_from_pending()
if not b:
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
if not self.process(self.buf):
return False
self.buf = b""
return True
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 = self.stream
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()
self.stream = None
self.environ = None
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 = self.stream
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:
s.message.data = None
s.message = None
return True
if s.pings:
for ping in s.pings:
self._write(s.pong(ping.data))
s.pings = []
if s.pongs:
for pong in s.pongs:
self.ponged(pong)
s.pongs = []
return True
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 = self.stream
try:
self.opened()
while not self.terminated:
if not self.once():
break
finally:
self.terminate()
class EchoWebSocket(WebSocket):
def received_message(self, message):
"""
Automatically sends back the provided ``message`` to
its originating endpoint.
"""
self.send(message.data, message.is_binary)