# Source code for ws4py.websocket

    # -*- 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 = 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

        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)