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# Contains code from https://github.com/MagicStack/uvloop/tree/v0.16.0
# SPDX-License-Identifier: PSF-2.0 AND (MIT OR Apache-2.0)
# SPDX-FileCopyrightText: Copyright (c) 2015-2021 MagicStack Inc. http://magic.io
import collections
import enum
import warnings
try:
import ssl
except ImportError: # pragma: no cover
ssl = None
from . import constants
from . import exceptions
from . import protocols
from . import transports
from .log import logger
if ssl is not None:
SSLAgainErrors = (ssl.SSLWantReadError, ssl.SSLSyscallError)
class SSLProtocolState(enum.Enum):
UNWRAPPED = "UNWRAPPED"
DO_HANDSHAKE = "DO_HANDSHAKE"
WRAPPED = "WRAPPED"
FLUSHING = "FLUSHING"
SHUTDOWN = "SHUTDOWN"
class AppProtocolState(enum.Enum):
# This tracks the state of app protocol (https://git.io/fj59P):
#
# INIT -cm-> CON_MADE [-dr*->] [-er-> EOF?] -cl-> CON_LOST
#
# * cm: connection_made()
# * dr: data_received()
# * er: eof_received()
# * cl: connection_lost()
STATE_INIT = "STATE_INIT"
STATE_CON_MADE = "STATE_CON_MADE"
STATE_EOF = "STATE_EOF"
STATE_CON_LOST = "STATE_CON_LOST"
def _create_transport_context(server_side, server_hostname):
if server_side:
raise ValueError('Server side SSL needs a valid SSLContext')
# Client side may pass ssl=True to use a default
# context; in that case the sslcontext passed is None.
# The default is secure for client connections.
# Python 3.4+: use up-to-date strong settings.
sslcontext = ssl.create_default_context()
if not server_hostname:
sslcontext.check_hostname = False
return sslcontext
def add_flowcontrol_defaults(high, low, kb):
if high is None:
if low is None:
hi = kb * 1024
else:
lo = low
hi = 4 * lo
else:
hi = high
if low is None:
lo = hi // 4
else:
lo = low
if not hi >= lo >= 0:
raise ValueError('high (%r) must be >= low (%r) must be >= 0' %
(hi, lo))
return hi, lo
class _SSLProtocolTransport(transports._FlowControlMixin,
transports.Transport):
_start_tls_compatible = True
_sendfile_compatible = constants._SendfileMode.FALLBACK
def __init__(self, loop, ssl_protocol):
self._loop = loop
self._ssl_protocol = ssl_protocol
self._closed = False
def get_extra_info(self, name, default=None):
"""Get optional transport information."""
return self._ssl_protocol._get_extra_info(name, default)
def set_protocol(self, protocol):
self._ssl_protocol._set_app_protocol(protocol)
def get_protocol(self):
return self._ssl_protocol._app_protocol
def is_closing(self):
return self._closed
def close(self):
"""Close the transport.
Buffered data will be flushed asynchronously. No more data
will be received. After all buffered data is flushed, the
protocol's connection_lost() method will (eventually) called
with None as its argument.
"""
if not self._closed:
self._closed = True
self._ssl_protocol._start_shutdown()
else:
self._ssl_protocol = None
def __del__(self, _warnings=warnings):
if not self._closed:
self._closed = True
_warnings.warn(
"unclosed transport <asyncio._SSLProtocolTransport "
"object>", ResourceWarning)
def is_reading(self):
return not self._ssl_protocol._app_reading_paused
def pause_reading(self):
"""Pause the receiving end.
No data will be passed to the protocol's data_received()
method until resume_reading() is called.
"""
self._ssl_protocol._pause_reading()
def resume_reading(self):
"""Resume the receiving end.
Data received will once again be passed to the protocol's
data_received() method.
"""
self._ssl_protocol._resume_reading()
def set_write_buffer_limits(self, high=None, low=None):
"""Set the high- and low-water limits for write flow control.
These two values control when to call the protocol's
pause_writing() and resume_writing() methods. If specified,
the low-water limit must be less than or equal to the
high-water limit. Neither value can be negative.
The defaults are implementation-specific. If only the
high-water limit is given, the low-water limit defaults to an
implementation-specific value less than or equal to the
high-water limit. Setting high to zero forces low to zero as
well, and causes pause_writing() to be called whenever the
buffer becomes non-empty. Setting low to zero causes
resume_writing() to be called only once the buffer is empty.
Use of zero for either limit is generally sub-optimal as it
reduces opportunities for doing I/O and computation
concurrently.
"""
self._ssl_protocol._set_write_buffer_limits(high, low)
self._ssl_protocol._control_app_writing()
def get_write_buffer_limits(self):
return (self._ssl_protocol._outgoing_low_water,
self._ssl_protocol._outgoing_high_water)
def get_write_buffer_size(self):
"""Return the current size of the write buffers."""
return self._ssl_protocol._get_write_buffer_size()
def set_read_buffer_limits(self, high=None, low=None):
"""Set the high- and low-water limits for read flow control.
These two values control when to call the upstream transport's
pause_reading() and resume_reading() methods. If specified,
the low-water limit must be less than or equal to the
high-water limit. Neither value can be negative.
The defaults are implementation-specific. If only the
high-water limit is given, the low-water limit defaults to an
implementation-specific value less than or equal to the
high-water limit. Setting high to zero forces low to zero as
well, and causes pause_reading() to be called whenever the
buffer becomes non-empty. Setting low to zero causes
resume_reading() to be called only once the buffer is empty.
Use of zero for either limit is generally sub-optimal as it
reduces opportunities for doing I/O and computation
concurrently.
"""
self._ssl_protocol._set_read_buffer_limits(high, low)
self._ssl_protocol._control_ssl_reading()
def get_read_buffer_limits(self):
return (self._ssl_protocol._incoming_low_water,
self._ssl_protocol._incoming_high_water)
def get_read_buffer_size(self):
"""Return the current size of the read buffer."""
return self._ssl_protocol._get_read_buffer_size()
@property
def _protocol_paused(self):
# Required for sendfile fallback pause_writing/resume_writing logic
return self._ssl_protocol._app_writing_paused
def write(self, data):
"""Write some data bytes to the transport.
This does not block; it buffers the data and arranges for it
to be sent out asynchronously.
"""
if not isinstance(data, (bytes, bytearray, memoryview)):
raise TypeError(f"data: expecting a bytes-like instance, "
f"got {type(data).__name__}")
if not data:
return
self._ssl_protocol._write_appdata((data,))
def writelines(self, list_of_data):
"""Write a list (or any iterable) of data bytes to the transport.
The default implementation concatenates the arguments and
calls write() on the result.
"""
self._ssl_protocol._write_appdata(list_of_data)
def write_eof(self):
"""Close the write end after flushing buffered data.
This raises :exc:`NotImplementedError` right now.
"""
raise NotImplementedError
def can_write_eof(self):
"""Return True if this transport supports write_eof(), False if not."""
return False
def abort(self):
"""Close the transport immediately.
Buffered data will be lost. No more data will be received.
The protocol's connection_lost() method will (eventually) be
called with None as its argument.
"""
self._force_close(None)
def _force_close(self, exc):
self._closed = True
if self._ssl_protocol is not None:
self._ssl_protocol._abort(exc)
def _test__append_write_backlog(self, data):
# for test only
self._ssl_protocol._write_backlog.append(data)
self._ssl_protocol._write_buffer_size += len(data)
class SSLProtocol(protocols.BufferedProtocol):
max_size = 256 * 1024 # Buffer size passed to read()
_handshake_start_time = None
_handshake_timeout_handle = None
_shutdown_timeout_handle = None
def __init__(self, loop, app_protocol, sslcontext, waiter,
server_side=False, server_hostname=None,
call_connection_made=True,
ssl_handshake_timeout=None,
ssl_shutdown_timeout=None):
if ssl is None:
raise RuntimeError("stdlib ssl module not available")
self._ssl_buffer = bytearray(self.max_size)
self._ssl_buffer_view = memoryview(self._ssl_buffer)
if ssl_handshake_timeout is None:
ssl_handshake_timeout = constants.SSL_HANDSHAKE_TIMEOUT
elif ssl_handshake_timeout <= 0:
raise ValueError(
f"ssl_handshake_timeout should be a positive number, "
f"got {ssl_handshake_timeout}")
if ssl_shutdown_timeout is None:
ssl_shutdown_timeout = constants.SSL_SHUTDOWN_TIMEOUT
elif ssl_shutdown_timeout <= 0:
raise ValueError(
f"ssl_shutdown_timeout should be a positive number, "
f"got {ssl_shutdown_timeout}")
if not sslcontext:
sslcontext = _create_transport_context(
server_side, server_hostname)
self._server_side = server_side
if server_hostname and not server_side:
self._server_hostname = server_hostname
else:
self._server_hostname = None
self._sslcontext = sslcontext
# SSL-specific extra info. More info are set when the handshake
# completes.
self._extra = dict(sslcontext=sslcontext)
# App data write buffering
self._write_backlog = collections.deque()
self._write_buffer_size = 0
self._waiter = waiter
self._loop = loop
self._set_app_protocol(app_protocol)
self._app_transport = None
self._app_transport_created = False
# transport, ex: SelectorSocketTransport
self._transport = None
self._ssl_handshake_timeout = ssl_handshake_timeout
self._ssl_shutdown_timeout = ssl_shutdown_timeout
# SSL and state machine
self._incoming = ssl.MemoryBIO()
self._outgoing = ssl.MemoryBIO()
self._state = SSLProtocolState.UNWRAPPED
self._conn_lost = 0 # Set when connection_lost called
if call_connection_made:
self._app_state = AppProtocolState.STATE_INIT
else:
self._app_state = AppProtocolState.STATE_CON_MADE
self._sslobj = self._sslcontext.wrap_bio(
self._incoming, self._outgoing,
server_side=self._server_side,
server_hostname=self._server_hostname)
# Flow Control
self._ssl_writing_paused = False
self._app_reading_paused = False
self._ssl_reading_paused = False
self._incoming_high_water = 0
self._incoming_low_water = 0
self._set_read_buffer_limits()
self._eof_received = False
self._app_writing_paused = False
self._outgoing_high_water = 0
self._outgoing_low_water = 0
self._set_write_buffer_limits()
self._get_app_transport()
def _set_app_protocol(self, app_protocol):
self._app_protocol = app_protocol
# Make fast hasattr check first
if (hasattr(app_protocol, 'get_buffer') and
isinstance(app_protocol, protocols.BufferedProtocol)):
self._app_protocol_get_buffer = app_protocol.get_buffer
self._app_protocol_buffer_updated = app_protocol.buffer_updated
self._app_protocol_is_buffer = True
else:
self._app_protocol_is_buffer = False
def _wakeup_waiter(self, exc=None):
if self._waiter is None:
return
if not self._waiter.cancelled():
if exc is not None:
self._waiter.set_exception(exc)
else:
self._waiter.set_result(None)
self._waiter = None
def _get_app_transport(self):
if self._app_transport is None:
if self._app_transport_created:
raise RuntimeError('Creating _SSLProtocolTransport twice')
self._app_transport = _SSLProtocolTransport(self._loop, self)
self._app_transport_created = True
return self._app_transport
def connection_made(self, transport):
"""Called when the low-level connection is made.
Start the SSL handshake.
"""
self._transport = transport
self._start_handshake()
def connection_lost(self, exc):
"""Called when the low-level connection is lost or closed.
The argument is an exception object or None (the latter
meaning a regular EOF is received or the connection was
aborted or closed).
"""
self._write_backlog.clear()
self._outgoing.read()
self._conn_lost += 1
# Just mark the app transport as closed so that its __dealloc__
# doesn't complain.
if self._app_transport is not None:
self._app_transport._closed = True
if self._state != SSLProtocolState.DO_HANDSHAKE:
if (
self._app_state == AppProtocolState.STATE_CON_MADE or
self._app_state == AppProtocolState.STATE_EOF
):
self._app_state = AppProtocolState.STATE_CON_LOST
self._loop.call_soon(self._app_protocol.connection_lost, exc)
self._set_state(SSLProtocolState.UNWRAPPED)
self._transport = None
self._app_transport = None
self._app_protocol = None
self._wakeup_waiter(exc)
if self._shutdown_timeout_handle:
self._shutdown_timeout_handle.cancel()
self._shutdown_timeout_handle = None
if self._handshake_timeout_handle:
self._handshake_timeout_handle.cancel()
self._handshake_timeout_handle = None
def get_buffer(self, n):
want = n
if want <= 0 or want > self.max_size:
want = self.max_size
if len(self._ssl_buffer) < want:
self._ssl_buffer = bytearray(want)
self._ssl_buffer_view = memoryview(self._ssl_buffer)
return self._ssl_buffer_view
def buffer_updated(self, nbytes):
self._incoming.write(self._ssl_buffer_view[:nbytes])
if self._state == SSLProtocolState.DO_HANDSHAKE:
self._do_handshake()
elif self._state == SSLProtocolState.WRAPPED:
self._do_read()
elif self._state == SSLProtocolState.FLUSHING:
self._do_flush()
elif self._state == SSLProtocolState.SHUTDOWN:
self._do_shutdown()
def eof_received(self):
"""Called when the other end of the low-level stream
is half-closed.
If this returns a false value (including None), the transport
will close itself. If it returns a true value, closing the
transport is up to the protocol.
"""
self._eof_received = True
try:
if self._loop.get_debug():
logger.debug("%r received EOF", self)
if self._state == SSLProtocolState.DO_HANDSHAKE:
self._on_handshake_complete(ConnectionResetError)
elif self._state == SSLProtocolState.WRAPPED:
self._set_state(SSLProtocolState.FLUSHING)
if self._app_reading_paused:
return True
else:
self._do_flush()
elif self._state == SSLProtocolState.FLUSHING:
self._do_write()
self._set_state(SSLProtocolState.SHUTDOWN)
self._do_shutdown()
elif self._state == SSLProtocolState.SHUTDOWN:
self._do_shutdown()
except Exception:
self._transport.close()
raise
def _get_extra_info(self, name, default=None):
if name in self._extra:
return self._extra[name]
elif self._transport is not None:
return self._transport.get_extra_info(name, default)
else:
return default
def _set_state(self, new_state):
allowed = False
if new_state == SSLProtocolState.UNWRAPPED:
allowed = True
elif (
self._state == SSLProtocolState.UNWRAPPED and
new_state == SSLProtocolState.DO_HANDSHAKE
):
allowed = True
elif (
self._state == SSLProtocolState.DO_HANDSHAKE and
new_state == SSLProtocolState.WRAPPED
):
allowed = True
elif (
self._state == SSLProtocolState.WRAPPED and
new_state == SSLProtocolState.FLUSHING
):
allowed = True
elif (
self._state == SSLProtocolState.FLUSHING and
new_state == SSLProtocolState.SHUTDOWN
):
allowed = True
if allowed:
self._state = new_state
else:
raise RuntimeError(
'cannot switch state from {} to {}'.format(
self._state, new_state))
# Handshake flow
def _start_handshake(self):
if self._loop.get_debug():
logger.debug("%r starts SSL handshake", self)
self._handshake_start_time = self._loop.time()
else:
self._handshake_start_time = None
self._set_state(SSLProtocolState.DO_HANDSHAKE)
# start handshake timeout count down
self._handshake_timeout_handle = \
self._loop.call_later(self._ssl_handshake_timeout,
lambda: self._check_handshake_timeout())
self._do_handshake()
def _check_handshake_timeout(self):
if self._state == SSLProtocolState.DO_HANDSHAKE:
msg = (
f"SSL handshake is taking longer than "
f"{self._ssl_handshake_timeout} seconds: "
f"aborting the connection"
)
self._fatal_error(ConnectionAbortedError(msg))
def _do_handshake(self):
try:
self._sslobj.do_handshake()
except SSLAgainErrors:
self._process_outgoing()
except ssl.SSLError as exc:
self._on_handshake_complete(exc)
else:
self._on_handshake_complete(None)
def _on_handshake_complete(self, handshake_exc):
if self._handshake_timeout_handle is not None:
self._handshake_timeout_handle.cancel()
self._handshake_timeout_handle = None
sslobj = self._sslobj
try:
if handshake_exc is None:
self._set_state(SSLProtocolState.WRAPPED)
else:
raise handshake_exc
peercert = sslobj.getpeercert()
except Exception as exc:
handshake_exc = None
self._set_state(SSLProtocolState.UNWRAPPED)
if isinstance(exc, ssl.CertificateError):
msg = 'SSL handshake failed on verifying the certificate'
else:
msg = 'SSL handshake failed'
self._fatal_error(exc, msg)
self._wakeup_waiter(exc)
return
if self._loop.get_debug():
dt = self._loop.time() - self._handshake_start_time
logger.debug("%r: SSL handshake took %.1f ms", self, dt * 1e3)
# Add extra info that becomes available after handshake.
self._extra.update(peercert=peercert,
cipher=sslobj.cipher(),
compression=sslobj.compression(),
ssl_object=sslobj)
if self._app_state == AppProtocolState.STATE_INIT:
self._app_state = AppProtocolState.STATE_CON_MADE
self._app_protocol.connection_made(self._get_app_transport())
self._wakeup_waiter()
self._do_read()
# Shutdown flow
def _start_shutdown(self):
if (
self._state in (
SSLProtocolState.FLUSHING,
SSLProtocolState.SHUTDOWN,
SSLProtocolState.UNWRAPPED
)
):
return
if self._app_transport is not None:
self._app_transport._closed = True
if self._state == SSLProtocolState.DO_HANDSHAKE:
self._abort(None)
else:
self._set_state(SSLProtocolState.FLUSHING)
self._shutdown_timeout_handle = self._loop.call_later(
self._ssl_shutdown_timeout,
lambda: self._check_shutdown_timeout()
)
self._do_flush()
def _check_shutdown_timeout(self):
if (
self._state in (
SSLProtocolState.FLUSHING,
SSLProtocolState.SHUTDOWN
)
):
self._transport._force_close(
exceptions.TimeoutError('SSL shutdown timed out'))
def _do_flush(self):
self._do_read()
self._set_state(SSLProtocolState.SHUTDOWN)
self._do_shutdown()
def _do_shutdown(self):
try:
if not self._eof_received:
self._sslobj.unwrap()
except SSLAgainErrors:
self._process_outgoing()
except ssl.SSLError as exc:
self._on_shutdown_complete(exc)
else:
self._process_outgoing()
self._call_eof_received()
self._on_shutdown_complete(None)
def _on_shutdown_complete(self, shutdown_exc):
if self._shutdown_timeout_handle is not None:
self._shutdown_timeout_handle.cancel()
self._shutdown_timeout_handle = None
if shutdown_exc:
self._fatal_error(shutdown_exc)
else:
self._loop.call_soon(self._transport.close)
def _abort(self, exc):
self._set_state(SSLProtocolState.UNWRAPPED)
if self._transport is not None:
self._transport._force_close(exc)
# Outgoing flow
def _write_appdata(self, list_of_data):
if (
self._state in (
SSLProtocolState.FLUSHING,
SSLProtocolState.SHUTDOWN,
SSLProtocolState.UNWRAPPED
)
):
if self._conn_lost >= constants.LOG_THRESHOLD_FOR_CONNLOST_WRITES:
logger.warning('SSL connection is closed')
self._conn_lost += 1
return
for data in list_of_data:
self._write_backlog.append(data)
self._write_buffer_size += len(data)
try:
if self._state == SSLProtocolState.WRAPPED:
self._do_write()
except Exception as ex:
self._fatal_error(ex, 'Fatal error on SSL protocol')
def _do_write(self):
try:
while self._write_backlog:
data = self._write_backlog[0]
count = self._sslobj.write(data)
data_len = len(data)
if count < data_len:
self._write_backlog[0] = data[count:]
self._write_buffer_size -= count
else:
del self._write_backlog[0]
self._write_buffer_size -= data_len
except SSLAgainErrors:
pass
self._process_outgoing()
def _process_outgoing(self):
if not self._ssl_writing_paused:
data = self._outgoing.read()
if len(data):
self._transport.write(data)
self._control_app_writing()
# Incoming flow
def _do_read(self):
if (
self._state not in (
SSLProtocolState.WRAPPED,
SSLProtocolState.FLUSHING,
)
):
return
try:
if not self._app_reading_paused:
if self._app_protocol_is_buffer:
self._do_read__buffered()
else:
self._do_read__copied()
if self._write_backlog:
self._do_write()
else:
self._process_outgoing()
self._control_ssl_reading()
except Exception as ex:
self._fatal_error(ex, 'Fatal error on SSL protocol')
def _do_read__buffered(self):
offset = 0
count = 1
buf = self._app_protocol_get_buffer(self._get_read_buffer_size())
wants = len(buf)
try:
count = self._sslobj.read(wants, buf)
if count > 0:
offset = count
while offset < wants:
count = self._sslobj.read(wants - offset, buf[offset:])
if count > 0:
offset += count
else:
break
else:
self._loop.call_soon(lambda: self._do_read())
except SSLAgainErrors:
pass
if offset > 0:
self._app_protocol_buffer_updated(offset)
if not count:
# close_notify
self._call_eof_received()
self._start_shutdown()
def _do_read__copied(self):
chunk = b'1'
zero = True
one = False
try:
while True:
chunk = self._sslobj.read(self.max_size)
if not chunk:
break
if zero:
zero = False
one = True
first = chunk
elif one:
one = False
data = [first, chunk]
else:
data.append(chunk)
except SSLAgainErrors:
pass
if one:
self._app_protocol.data_received(first)
elif not zero:
self._app_protocol.data_received(b''.join(data))
if not chunk:
# close_notify
self._call_eof_received()
self._start_shutdown()
def _call_eof_received(self):
try:
if self._app_state == AppProtocolState.STATE_CON_MADE:
self._app_state = AppProtocolState.STATE_EOF
keep_open = self._app_protocol.eof_received()
if keep_open:
logger.warning('returning true from eof_received() '
'has no effect when using ssl')
except (KeyboardInterrupt, SystemExit):
raise
except BaseException as ex:
self._fatal_error(ex, 'Error calling eof_received()')
# Flow control for writes from APP socket
def _control_app_writing(self):
size = self._get_write_buffer_size()
if size >= self._outgoing_high_water and not self._app_writing_paused:
self._app_writing_paused = True
try:
self._app_protocol.pause_writing()
except (KeyboardInterrupt, SystemExit):
raise
except BaseException as exc:
self._loop.call_exception_handler({
'message': 'protocol.pause_writing() failed',
'exception': exc,
'transport': self._app_transport,
'protocol': self,
})
elif size <= self._outgoing_low_water and self._app_writing_paused:
self._app_writing_paused = False
try:
self._app_protocol.resume_writing()
except (KeyboardInterrupt, SystemExit):
raise
except BaseException as exc:
self._loop.call_exception_handler({
'message': 'protocol.resume_writing() failed',
'exception': exc,
'transport': self._app_transport,
'protocol': self,
})
def _get_write_buffer_size(self):
return self._outgoing.pending + self._write_buffer_size
def _set_write_buffer_limits(self, high=None, low=None):
high, low = add_flowcontrol_defaults(
high, low, constants.FLOW_CONTROL_HIGH_WATER_SSL_WRITE)
self._outgoing_high_water = high
self._outgoing_low_water = low
# Flow control for reads to APP socket
def _pause_reading(self):
self._app_reading_paused = True
def _resume_reading(self):
if self._app_reading_paused:
self._app_reading_paused = False
def resume():
if self._state == SSLProtocolState.WRAPPED:
self._do_read()
elif self._state == SSLProtocolState.FLUSHING:
self._do_flush()
elif self._state == SSLProtocolState.SHUTDOWN:
self._do_shutdown()
self._loop.call_soon(resume)
# Flow control for reads from SSL socket
def _control_ssl_reading(self):
size = self._get_read_buffer_size()
if size >= self._incoming_high_water and not self._ssl_reading_paused:
self._ssl_reading_paused = True
self._transport.pause_reading()
elif size <= self._incoming_low_water and self._ssl_reading_paused:
self._ssl_reading_paused = False
self._transport.resume_reading()
def _set_read_buffer_limits(self, high=None, low=None):
high, low = add_flowcontrol_defaults(
high, low, constants.FLOW_CONTROL_HIGH_WATER_SSL_READ)
self._incoming_high_water = high
self._incoming_low_water = low
def _get_read_buffer_size(self):
return self._incoming.pending
# Flow control for writes to SSL socket
def pause_writing(self):
"""Called when the low-level transport's buffer goes over
the high-water mark.
"""
assert not self._ssl_writing_paused
self._ssl_writing_paused = True
def resume_writing(self):
"""Called when the low-level transport's buffer drains below
the low-water mark.
"""
assert self._ssl_writing_paused
self._ssl_writing_paused = False
self._process_outgoing()
def _fatal_error(self, exc, message='Fatal error on transport'):
if self._transport:
self._transport._force_close(exc)
if isinstance(exc, OSError):
if self._loop.get_debug():
logger.debug("%r: %s", self, message, exc_info=True)
elif not isinstance(exc, exceptions.CancelledError):
self._loop.call_exception_handler({
'message': message,
'exception': exc,
'transport': self._transport,
'protocol': self,
})