Method parse

src/websockets/protocol.py:562–639

Parse incoming data into frames. :meth:`receive_data` and :meth:`receive_eof` run this generator coroutine until it needs more data or reaches EOF. :meth:`parse` never raises an exception. Instead, it sets the :attr:`parser_exc` and yields control.

(self)

    # Private methods for receiving data.

    def parse(self) -> Generator[None]:
        """
        Parse incoming data into frames.

        :meth:`receive_data` and :meth:`receive_eof` run this generator
        coroutine until it needs more data or reaches EOF.

        :meth:`parse` never raises an exception. Instead, it sets the
        :attr:`parser_exc` and yields control.

        """
        try:
            while True:
                if (yield from self.reader.at_eof()):
                    if self.debug:
                        self.logger.debug("< EOF")
                    # If the WebSocket connection is closed cleanly, with a
                    # closing handhshake, recv_frame() substitutes parse()
                    # with discard(). This branch is reached only when the
                    # connection isn't closed cleanly.
                    raise EOFError("unexpected end of stream")

                max_size = None

                if self.max_message_size is not None:
                    if self.current_size is None:
                        max_size = self.max_message_size
                    else:
                        max_size = self.max_message_size - self.current_size

                if self.max_fragment_size is not None:
                    if max_size is None:
                        max_size = self.max_fragment_size
                    else:
                        max_size = min(max_size, self.max_fragment_size)

                # During a normal closure, execution ends here on the next
                # iteration of the loop after receiving a close frame. At
                # this point, recv_frame() replaced parse() by discard().
                frame = yield from Frame.parse(
                    self.reader.read_exact,
                    mask=self.side is SERVER,
                    max_size=max_size,
                    extensions=self.extensions,
                )

                if self.debug:
                    self.logger.debug("< %s", frame)

                self.recv_frame(frame)

        except ProtocolError as exc:
            self.fail(CloseCode.PROTOCOL_ERROR, str(exc))
            self.parser_exc = exc

        except EOFError as exc:
            self.fail(CloseCode.ABNORMAL_CLOSURE, str(exc))
            self.parser_exc = exc