""" # NOQA :mod:`aioopenssl` --- A transport for asyncio using :mod:`OpenSSL` ################################################################## This package provides a socket-based :class:`asyncio.Transport` which uses :mod:`OpenSSL` to create a TLS connection. Optionally, the TLS handshake can be deferred and performed later using :meth:`STARTTLSTransport.starttls`. .. note:: Use this module at your own risk. It has lower test coverage than I’d like it to have; it has been exported from aioxmpp on request, where it undergoes implicit testing. If you find bugs, please report them. If possible, add regression tests while you’re at it. If you find security-critical bugs, please follow the procedure announced in the `aioxmpp readme `_. The following function can be used to create a connection using the :class:`STARTTLSTransport`, which itself is documented below: .. autofunction:: create_starttls_connection The transport implementation is documented below: .. autoclass:: STARTTLSTransport(loop, rawsock, protocol, ssl_context_factory, [waiter=None], [use_starttls=False], [post_handshake_callback=None], [peer_hostname=None], [server_hostname=None]) :members: """ import asyncio import logging import socket import typing from enum import Enum from .version import __version__, version_info, version # noqa:F401 from .utils import SendWrap import OpenSSL.SSL logger = logging.getLogger(__name__) class _State(Enum): RAW_OPEN = 0x0000 # noqa:E221 RAW_EOF_RECEIVED = 0x0001 # noqa:E221 TLS_HANDSHAKING = 0x0300 # noqa:E221 TLS_OPEN = 0x0100 # noqa:E221 TLS_EOF_RECEIVED = 0x0101 # noqa:E221 TLS_SHUTTING_DOWN = 0x0102 # noqa:E221 TLS_SHUT_DOWN = 0x0103 # noqa:E221 CLOSED = 0x0003 # noqa:E221 @property def eof_received(self) -> bool: return bool(self.value & 0x0001) @property def tls_started(self) -> bool: return bool(self.value & 0x0100) @property def tls_handshaking(self) -> bool: return bool(self.value & 0x0200) @property def is_writable(self) -> bool: return not bool(self.value & 0x0002) @property def is_open(self) -> bool: return (self.value & 0x3) == 0 SSLContextFactory = typing.Callable[[asyncio.Transport], OpenSSL.SSL.Context] PostHandshakeCallback = typing.Callable[ ["STARTTLSTransport"], typing.Coroutine[typing.Any, typing.Any, None], ] class STARTTLSTransport(asyncio.Transport): """ Create a new :class:`asyncio.Transport` which supports TLS and the deferred starting of TLS using the :meth:`starttls` method. `loop` must be a :class:`asyncio.BaseEventLoop` with support for :meth:`BaseEventLoop.add_reader` as well as removal and the writer complements. `rawsock` must be a :class:`socket.socket` which will be used as the socket for the transport. `protocol` must be a :class:`asyncio.Protocol` which will be fed the data the transport receives. `ssl_context_factory` must be a callable accepting a single positional argument which returns a :class:`OpenSSL.SSL.Context`. The transport will be passed as the argument to the factory. The returned context will be used to create the :class:`OpenSSL.SSL.Connection` when TLS is enabled on the transport. If the callable is :data:`None`, a `ssl_context` must be supplied to :meth:`starttls` and `use_starttls` must be true. `use_starttls` must be a boolean value. If it is true, TLS is not enabled immediately. Instead, the user must call :meth:`starttls` to enable TLS on the transport. Until that point, the transport is unencrypted. If it is false, the TLS handshake is started immediately. This is roughly equivalent to calling :meth:`starttls` immediately. `peer_hostname` must be either a :class:`str` or :data:`None`. It may be used by certificate validators and must be the host name this transport actually connected to. That might be (e.g. in the case of XMPP) different from the actual domain name the transport communicates with (and for which the service must have a valid certificate). This host name may be used by certificate validators implementing e.g. DANE. `server_hostname` must be either a :class:`str` or :data:`None`. It may be used by certificate validators anrd must be the host name for which the peer must have a valid certificate (if host name based certificate validation is performed). `server_hostname` is also passed via the TLS Server Name Indication (SNI) extension if it is given. If host names are to be converted to :class:`bytes` by the transport, they are encoded using the ``utf-8`` codec. If `waiter` is not :data:`None`, it must be a :class:`asyncio.Future`. After the stream has been established, the futures result is set to a value of :data:`None`. If any errors occur, the exception is set on the future. If `use_starttls` is true, the future is fulfilled immediately after construction, as there is no blocking process which needs to take place. If `use_starttls` is false and thus TLS negotiation starts right away, the future is fulfilled when TLS negotiation is complete. `post_handshake_callback` may be a coroutine or :data:`None`. If it is not :data:`None`, it is called asynchronously after the TLS handshake and blocks the completion of the TLS handshake until it returns. It can be used to perform blocking post-handshake certificate verification, e.g. using DANE. The coroutine must not return a value. If it encounters an error, an appropriate exception should be raised, which will propagate out of :meth:`starttls` and/or passed to the `waiter` future. """ MAX_SIZE = 256 * 1024 def __init__( self, loop: asyncio.BaseEventLoop, rawsock: socket.socket, protocol: asyncio.Protocol, ssl_context_factory: typing.Optional[SSLContextFactory] = None, waiter: typing.Optional[asyncio.Future] = None, use_starttls: bool = False, post_handshake_callback: typing.Optional[ PostHandshakeCallback ] = None, peer_hostname: typing.Optional[str] = None, server_hostname: typing.Optional[str] = None): if not use_starttls and not ssl_context_factory: raise ValueError("Cannot have STARTTLS disabled (i.e. immediate " "TLS connection) and without SSL context.") super().__init__() self._rawsock = rawsock self._raw_fd = rawsock.fileno() self._trace_logger = logger.getChild( "trace.fd={}".format(self._raw_fd) ) self._sock = rawsock # type: typing.Union[socket.socket, OpenSSL.SSL.Connection] # noqa self._send_wrap = SendWrap(self._sock) self._protocol = protocol self._loop = loop self._extra = { "socket": rawsock, } # type: typing.Dict[str, typing.Any] self._waiter = waiter self._conn_lost = 0 self._buffer = bytearray() self._ssl_context_factory = ssl_context_factory self._extra.update( sslcontext=None, ssl_object=None, peername=self._rawsock.getpeername(), peer_hostname=peer_hostname, server_hostname=server_hostname ) # this is a list set of tasks which will also be cancelled if the # _waiter is cancelled self._chained_pending = set() # type: typing.Set[asyncio.Future] self._paused = False self._closing = False self._tls_conn = None # type: typing.Optional[OpenSSL.SSL.Connection] self._tls_read_wants_write = False self._tls_write_wants_read = False self._tls_post_handshake_callback = post_handshake_callback self._state = None # type: typing.Optional[_State] if not use_starttls: assert ssl_context_factory is not None self._ssl_context = ssl_context_factory(self) self._extra.update( sslcontext=self._ssl_context, ) self._initiate_tls() else: self._initiate_raw() def _waiter_done(self, fut: asyncio.Future) -> None: self._trace_logger.debug("_waiter future done (%r)", fut) for chained in self._chained_pending: self._trace_logger.debug("cancelling chained %r", chained) chained.cancel() self._chained_pending.clear() def _invalid_transition( self, via: typing.Optional[str] = None, to: typing.Optional[_State] = None) -> None: via_text = (" via {}".format(via)) if via is not None else "" to_text = (" to {}".format(to)) if to is not None else "" msg = "Invalid state transition (from {}{}{})".format( self._state, via_text, to_text ) logger.error(msg) raise RuntimeError(msg) def _invalid_state( self, what: str, exc: typing.Type[Exception] = RuntimeError, ) -> Exception: msg = "{what} (invalid in state {state}, closing={closing})".format( what=what, state=self._state, closing=self._closing) logger.error(msg) # raising is optional :) return exc(msg) def _fatal_error( self, exc: BaseException, msg: str) -> None: if not isinstance(exc, (BrokenPipeError, ConnectionResetError)): self._loop.call_exception_handler({ "message": msg, "exception": exc, "transport": self, "protocol": self._protocol }) self._force_close(exc) def _force_close( self, exc: typing.Optional[BaseException], ) -> None: self._trace_logger.debug("_force_close called") self._remove_rw() if self._state == _State.CLOSED: raise self._invalid_state("_force_close called") self._state = _State.CLOSED if self._buffer: self._buffer.clear() if self._waiter is not None and not self._waiter.done(): self._waiter.set_exception( exc or ConnectionError("_force_close() called"), ) self._loop.remove_reader(self._raw_fd) self._loop.remove_writer(self._raw_fd) self._loop.call_soon(self._call_connection_lost_and_clean_up, exc) def _remove_rw(self) -> None: self._trace_logger.debug("clearing readers/writers") self._loop.remove_reader(self._raw_fd) self._loop.remove_writer(self._raw_fd) def _call_connection_lost_and_clean_up( self, exc: Exception, ) -> None: """ Clean up all resources and call the protocols connection lost method. """ self._state = _State.CLOSED try: self._protocol.connection_lost(exc) finally: self._rawsock.close() if self._tls_conn is not None: self._tls_conn.set_app_data(None) self._tls_conn = None self._rawsock = None # type:ignore self._protocol = None # type:ignore def _initiate_raw(self) -> None: if self._state is not None: self._invalid_transition(via="_initiate_raw", to=_State.RAW_OPEN) self._state = _State.RAW_OPEN self._loop.add_reader(self._raw_fd, self._read_ready) self._loop.call_soon(self._protocol.connection_made, self) if self._waiter is not None: self._loop.call_soon(self._waiter.set_result, None) self._waiter = None def _initiate_tls(self) -> None: self._trace_logger.debug("_initiate_tls called") if self._state is not None and self._state != _State.RAW_OPEN: self._invalid_transition(via="_initiate_tls", to=_State.TLS_HANDSHAKING) self._tls_was_starttls = (self._state == _State.RAW_OPEN) self._state = _State.TLS_HANDSHAKING self._tls_conn = OpenSSL.SSL.Connection( self._ssl_context, self._sock) self._tls_conn.set_connect_state() self._tls_conn.set_app_data(self) try: self._tls_conn.set_tlsext_host_name( self._extra["server_hostname"].encode("IDNA")) except KeyError: pass self._sock = self._tls_conn self._send_wrap = SendWrap(self._sock) self._extra.update( ssl_object=self._tls_conn ) self._tls_do_handshake() def _tls_do_handshake(self) -> None: assert self._tls_conn is not None self._trace_logger.debug("_tls_do_handshake called") if self._state != _State.TLS_HANDSHAKING: raise self._invalid_state("_tls_do_handshake called") try: self._tls_conn.do_handshake() except OpenSSL.SSL.WantReadError: self._trace_logger.debug( "registering reader for _tls_do_handshake") self._loop.add_reader(self._raw_fd, self._tls_do_handshake) return except OpenSSL.SSL.WantWriteError: self._trace_logger.debug( "registering writer for _tls_do_handshake") self._loop.add_writer(self._raw_fd, self._tls_do_handshake) return except Exception as exc: self._remove_rw() self._fatal_error(exc, "Fatal error on tls handshake") if self._waiter is not None: self._waiter.set_exception(exc) return except BaseException as exc: self._remove_rw() if self._waiter is not None: self._waiter.set_exception(exc) raise self._remove_rw() # handshake complete self._trace_logger.debug("handshake complete") self._extra.update( peercert=self._tls_conn.get_peer_certificate() ) if self._tls_post_handshake_callback: self._trace_logger.debug("post handshake scheduled via callback") task = asyncio.ensure_future( self._tls_post_handshake_callback(self) ) task.add_done_callback(self._tls_post_handshake_done) self._chained_pending.add(task) self._tls_post_handshake_callback = None else: self._tls_post_handshake(None) def _tls_post_handshake_done( self, task: asyncio.Future, ) -> None: self._chained_pending.discard(task) try: task.result() except asyncio.CancelledError: # canceled due to closure or something similar pass except BaseException as err: self._tls_post_handshake(err) else: self._tls_post_handshake(None) def _tls_post_handshake( self, exc: typing.Optional[BaseException], ) -> None: self._trace_logger.debug("_tls_post_handshake called") if exc is not None: if self._waiter is not None and not self._waiter.done(): self._waiter.set_exception(exc) self._fatal_error(exc, "Fatal error on post-handshake callback") return self._tls_read_wants_write = False self._tls_write_wants_read = False self._state = _State.TLS_OPEN self._loop.add_reader(self._raw_fd, self._read_ready) if not self._tls_was_starttls: self._loop.call_soon(self._protocol.connection_made, self) if self._waiter is not None: self._loop.call_soon(self._waiter.set_result, None) def _tls_do_shutdown(self) -> None: self._trace_logger.debug("_tls_do_shutdown called") if self._state != _State.TLS_SHUTTING_DOWN: raise self._invalid_state("_tls_do_shutdown called") assert isinstance(self._sock, OpenSSL.SSL.Connection) try: self._sock.shutdown() except OpenSSL.SSL.WantReadError: self._trace_logger.debug("registering reader for _tls_shutdown") self._loop.add_reader(self._raw_fd, self._tls_shutdown) return except OpenSSL.SSL.WantWriteError: self._trace_logger.debug("registering writer for _tls_shutdown") self._loop.add_writer(self._raw_fd, self._tls_shutdown) return except Exception as exc: # force_close will take care of removing rw handlers self._fatal_error(exc, "Fatal error on tls shutdown") return except BaseException: self._remove_rw() raise self._remove_rw() self._state = _State.TLS_SHUT_DOWN # continue to raw shut down self._raw_shutdown() def _tls_shutdown(self) -> None: self._state = _State.TLS_SHUTTING_DOWN self._tls_do_shutdown() def _raw_shutdown(self) -> None: self._remove_rw() try: self._rawsock.shutdown(socket.SHUT_RDWR) except OSError: # we cannot do anything anyway if this fails pass self._force_close(None) def _read_ready(self) -> None: assert self._state is not None if self._state.tls_started and self._tls_write_wants_read: self._tls_write_wants_read = False self._write_ready() if self._buffer: self._trace_logger.debug("_read_ready: add writer for more" " data") self._loop.add_writer(self._raw_fd, self._write_ready) if self._state.eof_received: # no further reading return try: data = self._sock.recv(self.MAX_SIZE) except (BlockingIOError, InterruptedError, OpenSSL.SSL.WantReadError): pass except OpenSSL.SSL.WantWriteError: assert self._state.tls_started self._tls_read_wants_write = True self._trace_logger.debug("_read_ready: swap reader for writer") self._loop.remove_reader(self._raw_fd) self._loop.add_writer(self._raw_fd, self._write_ready) except OpenSSL.SSL.SysCallError as exc: if self._state in (_State.TLS_SHUT_DOWN, _State.TLS_SHUTTING_DOWN, _State.CLOSED): self._trace_logger.debug( "_read_ready: ignoring syscall exception during shutdown: " "%s", exc, ) else: self._fatal_error(exc, "Fatal read error on STARTTLS transport") except Exception as err: self._fatal_error(err, "Fatal read error on STARTTLS transport") return else: if data: self._protocol.data_received(data) else: keep_open = False try: keep_open = bool(self._protocol.eof_received()) finally: self._eof_received(keep_open) def _write_ready(self) -> None: assert self._state is not None if self._tls_read_wants_write: self._tls_read_wants_write = False self._read_ready() if not self._paused and not self._state.eof_received: self._trace_logger.debug("_write_ready: add reader for more" " data") self._loop.add_reader(self._raw_fd, self._read_ready) # do not send data during handshake! if self._buffer and self._state != _State.TLS_HANDSHAKING: try: nsent = self._send_wrap.send(self._buffer) except (BlockingIOError, InterruptedError, OpenSSL.SSL.WantWriteError): nsent = 0 except OpenSSL.SSL.WantReadError: nsent = 0 assert self._state.tls_started self._tls_write_wants_read = True self._trace_logger.debug( "_write_ready: swap writer for reader") self._loop.remove_writer(self._raw_fd) self._loop.add_reader(self._raw_fd, self._read_ready) except OpenSSL.SSL.SysCallError as exc: if self._state in (_State.TLS_SHUT_DOWN, _State.TLS_SHUTTING_DOWN, _State.CLOSED): self._trace_logger.debug( "_write_ready: ignoring syscall exception during " "shutdown: %s", exc, ) else: self._fatal_error(exc, "Fatal write error on STARTTLS " "transport") except Exception as err: self._fatal_error(err, "Fatal write error on STARTTLS " "transport") return if nsent: del self._buffer[:nsent] if not self._buffer: if not self._tls_read_wants_write: self._trace_logger.debug("_write_ready: nothing more to write," " removing writer") self._loop.remove_writer(self._raw_fd) if self._closing: if self._state.tls_started: self._tls_shutdown() else: self._raw_shutdown() def _eof_received(self, keep_open: bool) -> None: assert self._state is not None self._trace_logger.debug("_eof_received: removing reader") self._loop.remove_reader(self._raw_fd) if self._state.tls_started: assert self._tls_conn is not None if self._tls_conn.get_shutdown() & OpenSSL.SSL.RECEIVED_SHUTDOWN: # proper TLS shutdown going on if keep_open: self._state = _State.TLS_EOF_RECEIVED else: self._tls_shutdown() else: if keep_open: self._trace_logger.warning( "result of eof_received() ignored as shut down is" " improper", ) self._fatal_error( ConnectionError("Underlying transport closed"), "unexpected eof_received" ) else: if keep_open: self._state = _State.RAW_EOF_RECEIVED else: self._raw_shutdown() # public API def abort(self) -> None: """ Immediately close the stream, without sending remaining buffers or performing a proper shutdown. """ if self._state == _State.CLOSED: self._invalid_state("abort() called") return self._force_close(None) def can_write_eof(self) -> bool: """ Return :data:`False`. .. note:: Writing of EOF (i.e. closing the sending direction of the stream) is theoretically possible. However, it was deemed by the author that the case is rare enough to neglect it for the sake of implementation simplicity. """ return False def close(self) -> None: """ Close the stream. This performs a proper stream shutdown, except if the stream is currently performing a TLS handshake. In that case, calling :meth:`close` is equivalent to calling :meth:`abort`. Otherwise, the transport waits until all buffers are transmitted. """ if self._state == _State.CLOSED: self._invalid_state("close() called") return if self._state == _State.TLS_HANDSHAKING: # hard-close self._force_close(None) elif self._state == _State.TLS_SHUTTING_DOWN: # shut down in progress, nothing to do pass elif self._buffer: # there is data to be send left, first wait for it to transmit ... self._closing = True elif self._state is not None and self._state.tls_started: # normal TLS state, nothing left to transmit, shut down self._tls_shutdown() else: # normal non-TLS state, nothing left to transmit, close self._raw_shutdown() def get_extra_info( self, name: str, default: typing.Optional[typing.Any] = None, ) -> typing.Any: """ The following extra information is available: * ``socket``: the underlying :mod:`socket` object * ``sslcontext``: the :class:`OpenSSL.SSL.Context` object to use (this may be :data:`None` until :meth:`starttls` has been called) * ``ssl_object``: :class:`OpenSSL.SSL.Connection` object (:data:`None` if TLS is not enabled (yet)) * ``peername``: return value of :meth:`socket.Socket.getpeername` * ``peer_hostname``: The `peer_hostname` value passed to the constructor. * ``server_hostname``: The `server_hostname` value passed to the constructor. """ return self._extra.get(name, default) async def starttls( self, ssl_context: typing.Optional[OpenSSL.SSL.Context] = None, post_handshake_callback: typing.Optional[ PostHandshakeCallback ] = None, ) -> None: """ Start a TLS stream on top of the socket. This is an invalid operation if the stream is not in RAW_OPEN state. If `ssl_context` is set, it overrides the `ssl_context` passed to the constructor. If `post_handshake_callback` is set, it overrides the `post_handshake_callback` passed to the constructor. .. versionchanged:: 0.4 This method is now a barrier with respect to reads and writes: before the handshake is completed (including the post handshake callback, if any), no data is received or sent. """ if self._state != _State.RAW_OPEN or self._closing: raise self._invalid_state("starttls() called") if ssl_context is not None: self._ssl_context = ssl_context self._extra.update( sslcontext=ssl_context ) else: assert self._ssl_context_factory is not None self._ssl_context = self._ssl_context_factory(self) if post_handshake_callback is not None: self._tls_post_handshake_callback = post_handshake_callback self._waiter = asyncio.Future() self._waiter.add_done_callback(self._waiter_done) self._initiate_tls() try: await self._waiter finally: self._waiter = None def write(self, data: typing.Union[bytes, bytearray, memoryview]) -> None: """ Write data to the transport. This is an invalid operation if the stream is not writable, that is, if it is closed. During TLS negotiation, the data is buffered. """ if not isinstance(data, (bytes, bytearray, memoryview)): raise TypeError('data argument must be byte-ish (%r)', type(data)) if (self._state is None or not self._state.is_writable or self._closing): raise self._invalid_state("write() called") if not data: return if not self._buffer: self._loop.add_writer(self._raw_fd, self._write_ready) self._buffer.extend(data) def write_eof(self) -> None: """ Writing the EOF has not been implemented, for the sake of simplicity. """ raise NotImplementedError("Cannot write_eof() on STARTTLS transport") def can_starttls(self) -> bool: """ Return :data:`True`. """ return True def is_closing(self) -> bool: return (self._state == _State.TLS_SHUTTING_DOWN or self._state == _State.CLOSED) async def create_starttls_connection( loop: asyncio.BaseEventLoop, protocol_factory: typing.Callable[[], asyncio.Protocol], host: typing.Optional[str] = None, port: typing.Optional[int] = None, *, sock: typing.Optional[socket.socket] = None, ssl_context_factory: typing.Optional[SSLContextFactory] = None, use_starttls: bool = False, local_addr: typing.Any = None, **kwargs # type: typing.Any ) -> typing.Tuple[asyncio.Transport, asyncio.Protocol]: """ Create a connection which can later be upgraded to use TLS. .. versionchanged:: 0.4 The `local_addr` argument was added. :param loop: The event loop to use. :type loop: :class:`asyncio.BaseEventLoop` :param protocol_factory: Factory for the protocol for the connection :param host: The host name or address to connect to :type host: :class:`str` or :data:`None` :param port: The port to connect to :type port: :class:`int` or :data:`None` :param sock: A socket to wrap (conflicts with `host` and `port`) :type sock: :class:`socket.socket` :param ssl_context_factory: Function which returns a :class:`OpenSSL.SSL.Context` to use for TLS operations :param use_starttls: Flag to control whether TLS is negotiated right away or deferredly. :type use_starttls: :class:`bool` :param local_addr: Address to bind to This is roughly a copy of the asyncio implementation of :meth:`asyncio.BaseEventLoop.create_connection`. It returns a pair ``(transport, protocol)``, where `transport` is a newly created :class:`STARTTLSTransport` instance. Further keyword arguments are forwarded to the constructor of :class:`STARTTLSTransport`. `loop` must be a :class:`asyncio.BaseEventLoop`, with support for :meth:`asyncio.BaseEventLoop.add_reader` and the corresponding writer and removal functions for sockets. This is typically a selector type event loop. `protocol_factory` must be a callable which (without any arguments) returns a :class:`asyncio.Protocol` which will be connected to the STARTTLS transport. `host` and `port` must be a hostname and a port number, or both :data:`None`. Both must be :data:`None`, if and only if `sock` is not :data:`None`. In that case, `sock` is used instead of a newly created socket. `sock` is put into non-blocking mode and must be a stream socket. If `use_starttls` is :data:`True`, no TLS handshake will be performed initially. Instead, the connection is established without any transport-layer security. It is expected that the :meth:`STARTTLSTransport.starttls` method is used when the application protocol requires TLS. If `use_starttls` is :data:`False`, the TLS handshake is initiated right away. `local_addr` may be an address to bind this side of the socket to. If omitted or :data:`None`, the local address is assigned by the operating system. This coroutine returns when the stream is established. If `use_starttls` is :data:`False`, this means that the full TLS handshake has to be finished for this coroutine to return. Otherwise, no TLS handshake takes place. It must be invoked using the :meth:`STARTTLSTransport.starttls` coroutine. """ if host is not None and port is not None: host_addrs = await loop.getaddrinfo( host, port, type=socket.SOCK_STREAM, ) exceptions = [] for family, type, proto, cname, address in host_addrs: sock = None try: sock = socket.socket(family=family, type=type, proto=proto) sock.setblocking(False) if local_addr is not None: sock.bind(local_addr) await loop.sock_connect(sock, address) except OSError as exc: if sock is not None: sock.close() exceptions.append(exc) else: break else: if len(exceptions) == 1: raise exceptions[0] model = str(exceptions[0]) if all(str(exc) == model for exc in exceptions): raise exceptions[0] try: from aioxmpp.errors import MultiOSError # type:ignore except ImportError: MultiOSError = OSError raise MultiOSError( "could not connect to [{}]:{}".format(host, port), exceptions, ) elif sock is None: raise ValueError("sock must not be None if host and/or port are None") else: sock.setblocking(False) protocol = protocol_factory() waiter = asyncio.Future(loop=loop) # type: asyncio.Future[None] transport = STARTTLSTransport(loop, sock, protocol, ssl_context_factory=ssl_context_factory, waiter=waiter, use_starttls=use_starttls, **kwargs) await waiter return transport, protocol