# -*- coding: utf-8 -*- import struct from struct import unpack from ws4py.utf8validator import Utf8Validator from ws4py.messaging import TextMessage, BinaryMessage, CloseControlMessage,\ PingControlMessage, PongControlMessage from ws4py.framing import Frame, OPCODE_CONTINUATION, OPCODE_TEXT, \ OPCODE_BINARY, OPCODE_CLOSE, OPCODE_PING, OPCODE_PONG from ws4py.exc import FrameTooLargeException, ProtocolException, InvalidBytesError,\ TextFrameEncodingException, UnsupportedFrameTypeException, StreamClosed from ws4py.compat import py3k VALID_CLOSING_CODES = [1000, 1001, 1002, 1003, 1007, 1008, 1009, 1010, 1011] class Stream(object): def __init__(self, always_mask=False, expect_masking=True): """ Represents a websocket stream of bytes flowing in and out. The stream doesn't know about the data provider itself and doesn't even know about sockets. Instead the stream simply yields for more bytes whenever it requires them. The stream owner is responsible to provide the stream with those bytes until a frame can be interpreted. .. code-block:: python :linenos: >>> s = Stream() >>> s.parser.send(BYTES) >>> s.has_messages False >>> s.parser.send(MORE_BYTES) >>> s.has_messages True >>> s.message Set ``always_mask`` to mask all frames built. Set ``expect_masking`` to indicate masking will be checked on all parsed frames. """ self.message = None """ Parsed test or binary messages. Whenever the parser reads more bytes from a fragment message, those bytes are appended to the most recent message. """ self.pings = [] """ Parsed ping control messages. They are instances of :class:`ws4py.messaging.PingControlMessage` """ self.pongs = [] """ Parsed pong control messages. They are instances of :class:`ws4py.messaging.PongControlMessage` """ self.closing = None """ Parsed close control messsage. Instance of :class:`ws4py.messaging.CloseControlMessage` """ self.errors = [] """ Detected errors while parsing. Instances of :class:`ws4py.messaging.CloseControlMessage` """ self._parser = None """ Parser in charge to process bytes it is fed with. """ self.always_mask = always_mask self.expect_masking = expect_masking @property def parser(self): if self._parser is None: self._parser = self.receiver() # Python generators must be initialized once. next(self.parser) return self._parser def _cleanup(self): """ Frees the stream's resources rendering it unusable. """ self.message = None if self._parser is not None: if not self._parser.gi_running: self._parser.close() self._parser = None self.errors = None self.pings = None self.pongs = None self.closing = None def text_message(self, text): """ Returns a :class:`ws4py.messaging.TextMessage` instance ready to be built. Convenience method so that the caller doesn't need to import the :class:`ws4py.messaging.TextMessage` class itself. """ return TextMessage(text=text) def binary_message(self, bytes): """ Returns a :class:`ws4py.messaging.BinaryMessage` instance ready to be built. Convenience method so that the caller doesn't need to import the :class:`ws4py.messaging.BinaryMessage` class itself. """ return BinaryMessage(bytes) @property def has_message(self): """ Checks if the stream has received any message which, if fragmented, is now completed. """ if self.message is not None: return self.message.completed return False def close(self, code=1000, reason=''): """ Returns a close control message built from a :class:`ws4py.messaging.CloseControlMessage` instance, using the given status ``code`` and ``reason`` message. """ return CloseControlMessage(code=code, reason=reason) def ping(self, data=''): """ Returns a ping control message built from a :class:`ws4py.messaging.PingControlMessage` instance. """ return PingControlMessage(data).single(mask=self.always_mask) def pong(self, data=''): """ Returns a ping control message built from a :class:`ws4py.messaging.PongControlMessage` instance. """ return PongControlMessage(data).single(mask=self.always_mask) def receiver(self): """ Parser that keeps trying to interpret bytes it is fed with as incoming frames part of a message. Control message are single frames only while data messages, like text and binary, may be fragmented accross frames. The way it works is by instanciating a :class:`wspy.framing.Frame` object, then running its parser generator which yields how much bytes it requires to performs its task. The stream parser yields this value to its caller and feeds the frame parser. When the frame parser raises :exc:`StopIteration`, the stream parser tries to make sense of the parsed frame. It dispatches the frame's bytes to the most appropriate message type based on the frame's opcode. Overall this makes the stream parser totally agonstic to the data provider. """ utf8validator = Utf8Validator() running = True frame = None while running: frame = Frame() while 1: try: some_bytes = (yield next(frame.parser)) frame.parser.send(some_bytes) except GeneratorExit: running = False break except StopIteration: frame._cleanup() some_bytes = frame.body # Let's avoid unmasking when there is no payload if some_bytes: if frame.masking_key and self.expect_masking: some_bytes = frame.unmask(some_bytes) elif not frame.masking_key and self.expect_masking: msg = CloseControlMessage(code=1002, reason='Missing masking when expected') self.errors.append(msg) break elif frame.masking_key and not self.expect_masking: msg = CloseControlMessage(code=1002, reason='Masked when not expected') self.errors.append(msg) break else: # If we reach this stage, it's because # the frame wasn't masked and we didn't expect # it anyway. Therefore, on py2k, the bytes # are actually a str object and can't be used # in the utf8 validator as we need integers # when we get each byte one by one. # Our only solution here is to convert our # string to a bytearray. some_bytes = bytearray(some_bytes) if frame.opcode == OPCODE_TEXT: if self.message and not self.message.completed: # We got a text frame before we completed the previous one msg = CloseControlMessage(code=1002, reason='Received a new message before completing previous') self.errors.append(msg) break m = TextMessage(some_bytes) m.completed = (frame.fin == 1) self.message = m if some_bytes: is_valid, end_on_code_point, _, _ = utf8validator.validate(some_bytes) if not is_valid or (m.completed and not end_on_code_point): self.errors.append(CloseControlMessage(code=1007, reason='Invalid UTF-8 bytes')) break elif frame.opcode == OPCODE_BINARY: if self.message and not self.message.completed: # We got a text frame before we completed the previous one msg = CloseControlMessage(code=1002, reason='Received a new message before completing previous') self.errors.append(msg) break m = BinaryMessage(some_bytes) m.completed = (frame.fin == 1) self.message = m elif frame.opcode == OPCODE_CONTINUATION: m = self.message if m is None: self.errors.append(CloseControlMessage(code=1002, reason='Message not started yet')) break m.extend(some_bytes) m.completed = (frame.fin == 1) if m.opcode == OPCODE_TEXT: if some_bytes: is_valid, end_on_code_point, _, _ = utf8validator.validate(some_bytes) if not is_valid or (m.completed and not end_on_code_point): self.errors.append(CloseControlMessage(code=1007, reason='Invalid UTF-8 bytes')) break elif frame.opcode == OPCODE_CLOSE: code = 1005 reason = "" if frame.payload_length == 0: self.closing = CloseControlMessage(code=1005) elif frame.payload_length == 1: self.closing = CloseControlMessage(code=1005, reason='Payload has invalid length') else: try: # at this stage, some_bytes have been unmasked # so actually are held in a bytearray code = int(unpack("!H", bytes(some_bytes[0:2]))[0]) except struct.error: reason = 'Failed at decoding closing code' else: # Those codes are reserved or plainly forbidden if code not in VALID_CLOSING_CODES and not (2999 < code < 5000): reason = 'Invalid Closing Frame Code: %d' % code code = 1005 elif frame.payload_length > 1: reason = some_bytes[2:] if frame.masking_key else frame.body[2:] if not py3k: reason = bytearray(reason) is_valid, end_on_code_point, _, _ = utf8validator.validate(reason) if not is_valid or not end_on_code_point: self.errors.append(CloseControlMessage(code=1007, reason='Invalid UTF-8 bytes')) break reason = bytes(reason) self.closing = CloseControlMessage(code=code, reason=reason) elif frame.opcode == OPCODE_PING: self.pings.append(PingControlMessage(some_bytes)) elif frame.opcode == OPCODE_PONG: self.pongs.append(PongControlMessage(some_bytes)) else: self.errors.append(CloseControlMessage(code=1003)) break except ProtocolException: self.errors.append(CloseControlMessage(code=1002)) break except FrameTooLargeException: self.errors.append(CloseControlMessage(code=1002, reason="Frame was too large")) break frame._cleanup() frame.body = None frame = None if self.message is not None and self.message.completed: utf8validator.reset() utf8validator.reset() utf8validator = None self._cleanup()