/usr/lib/python3/dist-packages/asyncssh/channel.py is in python3-asyncssh 1.11.1-1.
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1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 | # Copyright (c) 2013-2016 by Ron Frederick <ronf@timeheart.net>.
# All rights reserved.
#
# This program and the accompanying materials are made available under
# the terms of the Eclipse Public License v1.0 which accompanies this
# distribution and is available at:
#
# http://www.eclipse.org/legal/epl-v10.html
#
# Contributors:
# Ron Frederick - initial implementation, API, and documentation
"""SSH channel and session handlers"""
import asyncio
import binascii
from .constants import DEFAULT_LANG, DISC_PROTOCOL_ERROR, EXTENDED_DATA_STDERR
from .constants import MSG_CHANNEL_OPEN, MSG_CHANNEL_WINDOW_ADJUST
from .constants import MSG_CHANNEL_DATA, MSG_CHANNEL_EXTENDED_DATA
from .constants import MSG_CHANNEL_EOF, MSG_CHANNEL_CLOSE, MSG_CHANNEL_REQUEST
from .constants import MSG_CHANNEL_SUCCESS, MSG_CHANNEL_FAILURE
from .constants import OPEN_CONNECT_FAILED, PTY_OP_RESERVED, PTY_OP_END
from .constants import OPEN_REQUEST_X11_FORWARDING_FAILED
from .constants import OPEN_REQUEST_PTY_FAILED, OPEN_REQUEST_SESSION_FAILED
from .editor import SSHLineEditorChannel, SSHLineEditorSession
from .misc import ChannelOpenError, DisconnectError, map_handler_name
from .packet import Boolean, Byte, String, UInt32, SSHPacketHandler
class SSHChannel(SSHPacketHandler):
"""Parent class for SSH channels"""
_read_datatypes = set()
_write_datatypes = set()
def __init__(self, conn, loop, encoding, window, max_pktsize):
"""Initialize an SSH channel
If encoding is set, data sent and received will be in the form
of strings, converted on the wire to bytes using the specified
encoding. If encoding is None, data sent and received must be
provided as bytes.
Window specifies the initial receive window size.
Max_pktsize specifies the maximum length of a single data packet.
"""
self._conn = conn
self._loop = loop
self._session = None
self._encoding = encoding
self._extra = {'connection': conn}
self._env = {}
self._command = None
self._subsystem = None
self._send_state = 'closed'
self._send_chan = None
self._send_window = None
self._send_pktsize = None
self._send_paused = False
self._send_buf = []
self._send_buf_len = 0
self._recv_state = 'closed'
self._init_recv_window = window
self._recv_window = window
self._recv_pktsize = max_pktsize
self._recv_paused = True
self._recv_buf = []
self._recv_partial = {}
self._request_queue = []
self._open_waiter = None
self._request_waiters = []
self._close_event = asyncio.Event(loop=loop)
self.set_write_buffer_limits()
self._recv_chan = conn.add_channel(self)
def get_connection(self):
"""Return the connection used by this channel"""
return self._conn
def get_loop(self):
"""Return the event loop used by this channel"""
return self._loop
def get_encoding(self):
"""Return the encoding used by this channel"""
return self._encoding
def set_encoding(self, encoding):
"""Set the encoding on this channel"""
self._encoding = encoding
def get_recv_window(self):
"""Return the configured receive window for this channel"""
return self._init_recv_window
def get_read_datatypes(self):
"""Return the legal read data types for this channel"""
return self._read_datatypes
def get_write_datatypes(self):
"""Return the legal write data types for this channel"""
return self._write_datatypes
def _cleanup(self, exc=None):
"""Clean up this channel"""
if self._open_waiter:
if not self._open_waiter.cancelled(): # pragma: no branch
self._open_waiter.set_exception(
ChannelOpenError(OPEN_CONNECT_FAILED,
'SSH connection closed'))
self._open_waiter = None
if self._request_waiters:
for waiter in self._request_waiters:
if not waiter.cancelled(): # pragma: no branch
waiter.set_exception(exc)
self._request_waiters = []
if self._session:
self._session.connection_lost(exc)
self._session = None
self._close_event.set()
if self._conn: # pragma: no branch
self._conn.remove_channel(self._recv_chan)
self._recv_chan = None
self._conn = None
def _close_send(self):
"""Discard unsent data and close the channel for sending"""
# Discard unsent data
self._send_buf = []
self._send_buf_len = 0
if self._send_state != 'closed':
self._send_packet(MSG_CHANNEL_CLOSE)
self._send_chan = None
self._send_state = 'closed'
def _discard_recv(self):
"""Discard unreceived data and clean up if close received"""
# Discard unreceived data
self._recv_buf = []
self._recv_paused = False
# If recv is close_pending, we know send is already closed
if self._recv_state == 'close_pending':
self._recv_state = 'closed'
self._loop.call_soon(self._cleanup)
def _pause_resume_writing(self):
"""Pause or resume writing based on send buffer low/high water marks"""
if self._send_paused:
if self._send_buf_len <= self._send_low_water:
self._send_paused = False
self._session.resume_writing()
else:
if self._send_buf_len > self._send_high_water:
self._send_paused = True
self._session.pause_writing()
def _flush_send_buf(self):
"""Flush as much data in send buffer as the send window allows"""
while self._send_buf and self._send_window:
pktsize = min(self._send_window, self._send_pktsize)
buf, datatype = self._send_buf[0]
if len(buf) > pktsize:
data = buf[:pktsize]
del buf[:pktsize]
else:
data = buf
del self._send_buf[0]
self._send_buf_len -= len(data)
self._send_window -= len(data)
if datatype is None:
self._send_packet(MSG_CHANNEL_DATA, String(data))
else:
self._send_packet(MSG_CHANNEL_EXTENDED_DATA,
UInt32(datatype), String(data))
self._pause_resume_writing()
if not self._send_buf:
if self._send_state == 'eof_pending':
self._send_packet(MSG_CHANNEL_EOF)
self._send_state = 'eof'
elif self._send_state == 'close_pending':
self._close_send()
def _flush_recv_buf(self, exc=None):
"""Flush as much data in the recv buffer as the application allows"""
while self._recv_buf and not self._recv_paused:
self._deliver_data(*self._recv_buf.pop(0))
if not self._recv_buf:
if self._recv_state == 'eof_pending':
self._recv_state = 'eof'
if (not self._session.eof_received() and
self._send_state == 'open'):
self.write_eof()
elif self._recv_state == 'close_pending':
self._recv_state = 'closed'
if self._recv_partial and not exc:
exc = DisconnectError(DISC_PROTOCOL_ERROR,
'Unicode decode error')
self._loop.call_soon(self._cleanup, exc)
def _deliver_data(self, data, datatype):
"""Deliver incoming data to the session"""
self._recv_window -= len(data)
if self._recv_window < self._init_recv_window / 2:
self._send_packet(MSG_CHANNEL_WINDOW_ADJUST,
UInt32(self._init_recv_window -
self._recv_window))
self._recv_window = self._init_recv_window
if self._encoding:
if datatype in self._recv_partial:
encdata = self._recv_partial.pop(datatype) + data
else:
encdata = data
while encdata:
try:
data = encdata.decode(self._encoding)
encdata = b''
except UnicodeDecodeError as exc:
if exc.start > 0:
# Avoid pylint false positive
# pylint: disable=invalid-slice-index
data = encdata[:exc.start].decode()
encdata = encdata[exc.start:]
elif exc.reason == 'unexpected end of data':
break
else:
raise DisconnectError(DISC_PROTOCOL_ERROR,
'Unicode decode error')
self._session.data_received(data, datatype)
if encdata:
self._recv_partial[datatype] = encdata
else:
self._session.data_received(data, datatype)
def _accept_data(self, data, datatype=None):
"""Accept new data on the channel
This method accepts new data on the channel, immediately
delivering it to the session if it hasn't paused reading.
If it has paused, data is buffered until reading is resumed.
Data sent after the channel has been closed by the session
is dropped.
"""
if not data:
return
if self._send_state in {'close_pending', 'closed'}:
return
if len(data) > self._recv_window:
raise DisconnectError(DISC_PROTOCOL_ERROR, 'Window exceeded')
if self._recv_paused:
self._recv_buf.append((data, datatype))
else:
self._deliver_data(data, datatype)
def _service_next_request(self):
"""Process next item on channel request queue"""
request, packet, _ = self._request_queue[0]
name = '_process_' + map_handler_name(request) + '_request'
handler = getattr(self, name, None)
result = handler(packet) if callable(handler) else False
if result is not None:
self._report_response(result)
def _report_response(self, result):
"""Report back the response to a previously issued channel request"""
request, _, want_reply = self._request_queue.pop(0)
if want_reply and self._send_state not in {'close_pending', 'closed'}:
if result:
self._send_packet(MSG_CHANNEL_SUCCESS)
else:
self._send_packet(MSG_CHANNEL_FAILURE)
if result and request in {'shell', 'exec', 'subsystem'}:
self._session.session_started()
self.resume_reading()
if self._request_queue:
self._service_next_request()
def process_connection_close(self, exc):
"""Process the SSH connection closing"""
if self._send_state != 'closed':
self._send_state = 'closed'
if self._recv_state not in {'close_pending', 'closed'}:
self._recv_state = 'close_pending'
self._flush_recv_buf(exc)
elif self._recv_state == 'closed':
self._loop.call_soon(self._cleanup, exc)
def process_open(self, send_chan, send_window, send_pktsize, session):
"""Process a channel open request"""
self._send_chan = send_chan
self._send_window = send_window
self._send_pktsize = send_pktsize
self._conn.create_task(self._finish_open_request(session))
def _wrap_session(self, session):
"""Hook to optionally wrap channel and session objects"""
# By default, return the original channel and session objects
return self, session
@asyncio.coroutine
def _finish_open_request(self, session):
"""Finish processing a channel open request"""
# pylint: disable=broad-except
try:
if asyncio.iscoroutine(session):
session = yield from session
chan, self._session = self._wrap_session(session)
self._conn.send_channel_open_confirmation(self._send_chan,
self._recv_chan,
self._recv_window,
self._recv_pktsize)
self._send_state = 'open'
self._recv_state = 'open'
self._session.connection_made(chan)
except ChannelOpenError as exc:
self._conn.send_channel_open_failure(self._send_chan, exc.code,
exc.reason, exc.lang)
self._loop.call_soon(self._cleanup)
def process_open_confirmation(self, send_chan, send_window,
send_pktsize, packet):
"""Process a channel open confirmation"""
if not self._open_waiter:
raise DisconnectError(DISC_PROTOCOL_ERROR,
'Channel not being opened')
self._send_chan = send_chan
self._send_window = send_window
self._send_pktsize = send_pktsize
self._send_state = 'open'
self._recv_state = 'open'
if not self._open_waiter.cancelled(): # pragma: no branch
self._open_waiter.set_result(packet)
self._open_waiter = None
def process_open_failure(self, code, reason, lang):
"""Process a channel open failure"""
if not self._open_waiter:
raise DisconnectError(DISC_PROTOCOL_ERROR,
'Channel not being opened')
if not self._open_waiter.cancelled(): # pragma: no branch
self._open_waiter.set_exception(
ChannelOpenError(code, reason, lang))
self._open_waiter = None
self._loop.call_soon(self._cleanup)
def _process_window_adjust(self, pkttype, packet):
"""Process a send window adjustment"""
# pylint: disable=unused-argument
if self._recv_state not in {'open', 'eof_pending', 'eof'}:
raise DisconnectError(DISC_PROTOCOL_ERROR, 'Channel not open')
adjust = packet.get_uint32()
packet.check_end()
self._send_window += adjust
self._flush_send_buf()
def _process_data(self, pkttype, packet):
"""Process incoming data"""
# pylint: disable=unused-argument
if self._recv_state != 'open':
raise DisconnectError(DISC_PROTOCOL_ERROR,
'Channel not open for sending')
data = packet.get_string()
packet.check_end()
self._accept_data(data)
def _process_extended_data(self, pkttype, packet):
"""Process incoming extended data"""
# pylint: disable=unused-argument
if self._recv_state != 'open':
raise DisconnectError(DISC_PROTOCOL_ERROR,
'Channel not open for sending')
datatype = packet.get_uint32()
data = packet.get_string()
packet.check_end()
if datatype not in self._read_datatypes:
raise DisconnectError(DISC_PROTOCOL_ERROR,
'Invalid extended data type')
self._accept_data(data, datatype)
def _process_eof(self, pkttype, packet):
"""Process an incoming end of file"""
# pylint: disable=unused-argument
if self._recv_state != 'open':
raise DisconnectError(DISC_PROTOCOL_ERROR,
'Channel not open for sending')
packet.check_end()
self._recv_state = 'eof_pending'
self._flush_recv_buf()
def _process_close(self, pkttype, packet):
"""Process an incoming channel close"""
# pylint: disable=unused-argument
if self._recv_state not in {'open', 'eof_pending', 'eof'}:
raise DisconnectError(DISC_PROTOCOL_ERROR, 'Channel not open')
packet.check_end()
self._close_send()
self._recv_state = 'close_pending'
self._flush_recv_buf()
def _process_request(self, pkttype, packet):
"""Process an incoming channel request"""
# pylint: disable=unused-argument
if self._recv_state not in {'open', 'eof_pending', 'eof'}:
raise DisconnectError(DISC_PROTOCOL_ERROR, 'Channel not open')
request = packet.get_string()
want_reply = packet.get_boolean()
try:
request = request.decode('ascii')
except UnicodeDecodeError:
raise DisconnectError(DISC_PROTOCOL_ERROR,
'Invalid channel request') from None
self._request_queue.append((request, packet, want_reply))
if len(self._request_queue) == 1:
self._service_next_request()
def _process_response(self, pkttype, packet):
"""Process a success or failure response"""
packet.check_end()
if self._request_waiters:
waiter = self._request_waiters.pop(0)
if not waiter.cancelled(): # pragma: no branch
waiter.set_result(pkttype == MSG_CHANNEL_SUCCESS)
else:
raise DisconnectError(DISC_PROTOCOL_ERROR,
'Unexpected channel response')
packet_handlers = {
MSG_CHANNEL_WINDOW_ADJUST: _process_window_adjust,
MSG_CHANNEL_DATA: _process_data,
MSG_CHANNEL_EXTENDED_DATA: _process_extended_data,
MSG_CHANNEL_EOF: _process_eof,
MSG_CHANNEL_CLOSE: _process_close,
MSG_CHANNEL_REQUEST: _process_request,
MSG_CHANNEL_SUCCESS: _process_response,
MSG_CHANNEL_FAILURE: _process_response
}
@asyncio.coroutine
def _open(self, chantype, *args):
"""Make a request to open the channel"""
if self._send_state != 'closed':
raise OSError('Channel already open')
self._open_waiter = asyncio.Future(loop=self._loop)
self._conn.send_packet(Byte(MSG_CHANNEL_OPEN), String(chantype),
UInt32(self._recv_chan),
UInt32(self._recv_window),
UInt32(self._recv_pktsize), *args)
return (yield from self._open_waiter)
def _send_packet(self, pkttype, *args):
"""Send a packet on the channel"""
if self._send_chan is None: # pragma: no cover
return
self._conn.send_packet(Byte(pkttype), UInt32(self._send_chan), *args)
def _send_request(self, request, *args, want_reply=False):
"""Send a channel request"""
self._send_packet(MSG_CHANNEL_REQUEST, String(request),
Boolean(want_reply), *args)
@asyncio.coroutine
def _make_request(self, request, *args):
"""Make a channel request and wait for the response"""
if self._send_chan is None:
return False
waiter = asyncio.Future(loop=self._loop)
self._request_waiters.append(waiter)
self._send_request(request, *args, want_reply=True)
return (yield from waiter)
def abort(self):
"""Forcibly close the channel
This method can be called to forcibly close the channel, after
which no more data can be sent or received. Any unsent buffered
data and any incoming data in flight will be discarded.
"""
if self._send_state not in {'close_pending', 'closed'}:
# Send an immediate close, discarding unsent data
self._close_send()
if self._recv_state != 'closed':
# Discard unreceived data
self._discard_recv()
def close(self):
"""Cleanly close the channel
This method can be called to cleanly close the channel, after
which no more data can be sent or received. Any unsent buffered
data will be flushed asynchronously before the channel is
closed.
"""
if self._send_state not in {'close_pending', 'closed'}:
# Send a close only after sending unsent data
self._send_state = 'close_pending'
self._flush_send_buf()
if self._recv_state != 'closed':
# Discard unreceived data
self._discard_recv()
@asyncio.coroutine
def wait_closed(self):
"""Wait for this channel to close
This method is a coroutine which can be called to block until
this channel has finished closing.
"""
yield from self._close_event.wait()
def get_extra_info(self, name, default=None):
"""Get additional information about the channel
This method returns extra information about the channel once
it is established. Supported values include ``'connection'``
to return the SSH connection this channel is running over plus
all of the values supported on that connection.
For TCP channels, the values ``'local_peername'`` and
``'remote_peername'`` are added to return the local and remote
host and port information for the tunneled TCP connection.
For UNIX channels, the values ``'local_peername'`` and
``'remote_peername'`` are added to return the local and remote
path information for the tunneled UNIX domain socket connection.
Since UNIX domain sockets provide no "source" address, only
one of these will be filled in.
See :meth:`get_extra_info() <SSHClientConnection.get_extra_info>`
on :class:`SSHClientConnection` for more information.
"""
return self._extra.get(name, self._conn.get_extra_info(name, default)
if self._conn else default)
def can_write_eof(self):
"""Return whether the channel supports :meth:`write_eof`
This method always returns ``True``.
"""
# pylint: disable=no-self-use
return True
def get_write_buffer_size(self):
"""Return the current size of the channel's output buffer
This method returns how many bytes are currently in the
channel's output buffer waiting to be written.
"""
return self._send_buf_len
def set_write_buffer_limits(self, high=None, low=None):
"""Set the high- and low-water limits for write flow control
This method sets the limits used when deciding when to call
the ``pause_writing()`` and ``resume_writing()`` methods on
SSH sessions. Writing will be paused when the write buffer
size exceeds the high-water mark, and resumed when the
write buffer size equals or drops below the low-water mark.
"""
if high is None:
high = 4*low if low is not None else 65536
if low is None:
low = high // 4
if not 0 <= low <= high:
raise ValueError('high (%r) must be >= low (%r) must be >= 0' %
(high, low))
self._send_high_water = high
self._send_low_water = low
self._pause_resume_writing()
def write(self, data, datatype=None):
"""Write data on the channel
This method can be called to send data on the channel. If
an encoding was specified when the channel was created, the
data should be provided as a string and will be converted
using that encoding. Otherwise, the data should be provided
as bytes.
An extended data type can optionally be provided. For
instance, this is used from a :class:`SSHServerSession`
to write data to ``stderr``.
:param data:
The data to send on the channel
:param int datatype: (optional)
The extended data type of the data, from :ref:`extended
data types <ExtendedDataTypes>`
:type data: str or bytes
:raises: :exc:`OSError` if the channel isn't open for sending
or the extended data type is not valid for this type
of channel
"""
if self._send_state != 'open':
raise BrokenPipeError('Channel not open for sending')
if datatype is not None and datatype not in self._write_datatypes:
raise OSError('Invalid extended data type')
if len(data) == 0:
return
if self._encoding:
data = data.encode(self._encoding)
self._send_buf.append((bytearray(data), datatype))
self._send_buf_len += len(data)
self._flush_send_buf()
def writelines(self, list_of_data, datatype=None):
"""Write a list of data bytes on the channel
This method can be called to write a list (or any iterable) of
data bytes to the channel. It is functionality equivalent to
calling :meth:`write` on each element in the list.
:param list_of_data:
The data to send on the channel
:param int datatype: (optional)
The extended data type of the data, from :ref:`extended
data types <ExtendedDataTypes>`
:type list_of_data: iterable of str or bytes objects
:raises: :exc:`OSError` if the channel isn't open for sending
or the extended data type is not valid for this type
of channel
"""
sep = '' if self._encoding else b''
return self.write(sep.join(list_of_data), datatype)
def write_eof(self):
"""Write EOF on the channel
This method sends an end-of-file indication on the
channel, after which no more data can be sent. The
channel remains open, though, and data may still be
sent in the other direction.
:raises: :exc:`OSError` if the channel isn't open for sending
"""
if self._send_state == 'open':
self._send_state = 'eof_pending'
self._flush_send_buf()
def pause_reading(self):
"""Pause delivery of incoming data
This method is used to temporarily suspend delivery of incoming
channel data. After this call, incoming data will no longer
be delivered until :meth:`resume_reading` is called. Data will be
buffered locally up to the configured SSH channel window size,
but window updates will no longer be sent, eventually causing
back pressure on the remote system.
.. note:: Channel close notifications are not suspended by this
call. If the remote system closes the channel while
delivery is suspended, the channel will be closed even
though some buffered data may not have been delivered.
"""
self._recv_paused = True
def resume_reading(self):
"""Resume delivery of incoming data
This method can be called to resume delivery of incoming data
which was suspended by a call to :meth:`pause_reading`. As soon
as this method is called, any buffered data will be delivered
immediately. A pending end-of-file notication may also be
delivered if one was queued while reading was paused.
"""
if self._recv_paused:
self._recv_paused = False
self._flush_recv_buf()
def get_environment(self):
"""Return the environment for this session
This method returns the environment set by the client when
the session was opened. On the server, calls to this method
should only be made after :meth:`session_started
<SSHServerSession.session_started>` has been called on the
:class:`SSHServerSession`. When using the stream-based API,
calls to this can be made at any time after the handler
function has started up.
:returns: A dictionary containing the environment variables
set by the client
"""
return self._env
def get_command(self):
"""Return the command the client requested to execute, if any
This method returns the command the client requested to
execute when the session was opened, if any. If the client
did not request that a command be executed, this method
will return ``None``. On the server, alls to this method
should only be made after :meth:`session_started
<SSHServerSession.session_started>` has been called on the
:class:`SSHServerSession`. When using the stream-based API,
calls to this can be made at any time after the handler
function has started up.
"""
return self._command
def get_subsystem(self):
"""Return the subsystem the client requested to open, if any
This method returns the subsystem the client requested to
open when the session was opened, if any. If the client
did not request that a subsystem be opened, this method will
return ``None``. On the server, calls to this method should
only be made after :meth:`session_started
<SSHServerSession.session_started>` has been called on the
:class:`SSHServerSession`. When using the stream-based API,
calls to this can be made at any time after the handler
function has started up.
"""
return self._subsystem
class SSHClientChannel(SSHChannel):
"""SSH client channel"""
_read_datatypes = {EXTENDED_DATA_STDERR}
def __init__(self, conn, loop, encoding, window, max_pktsize):
super().__init__(conn, loop, encoding, window, max_pktsize)
self._exit_status = None
self._exit_signal = None
def _cleanup(self, exc=None):
"""Clean up this channel"""
if self._conn: # pragma: no branch
self._conn.detach_x11_listener(self)
super()._cleanup(exc)
@asyncio.coroutine
def create(self, session_factory, command, subsystem, env, term_type,
term_size, term_modes, x11_forwarding, x11_display,
x11_auth_path, x11_single_connection, agent_forwarding):
"""Create an SSH client session"""
packet = yield from self._open(b'session')
# Client sessions should have no extra data in the open confirmation
packet.check_end()
self._session = session_factory()
self._session.connection_made(self)
self._env = env
self._command = command
self._subsystem = subsystem
for name, value in env.items():
self._send_request(b'env', String(str(name)), String(str(value)))
if term_type:
if not term_size:
width = height = pixwidth = pixheight = 0
elif len(term_size) == 2:
width, height = term_size
pixwidth = pixheight = 0
elif len(term_size) == 4:
width, height, pixwidth, pixheight = term_size
else:
raise ValueError('If set, terminal size must be a tuple of '
'2 or 4 integers')
modes = b''
for mode, value in term_modes.items():
if mode <= PTY_OP_END or mode >= PTY_OP_RESERVED:
raise ValueError('Invalid pty mode: %s' % mode)
modes += Byte(mode) + UInt32(value)
modes += Byte(PTY_OP_END)
if not (yield from self._make_request(b'pty-req',
String(term_type),
UInt32(width),
UInt32(height),
UInt32(pixwidth),
UInt32(pixheight),
String(modes))):
self.close()
raise ChannelOpenError(OPEN_REQUEST_PTY_FAILED,
'PTY request failed')
if x11_forwarding:
try:
auth_proto, remote_auth, screen = \
yield from self._conn.attach_x11_listener(
self, x11_display, x11_auth_path, x11_single_connection)
except ValueError as exc:
raise ChannelOpenError(OPEN_REQUEST_X11_FORWARDING_FAILED,
str(exc)) from None
result = yield from self._make_request(
b'x11-req', Boolean(x11_single_connection), String(auth_proto),
String(binascii.b2a_hex(remote_auth)), UInt32(screen))
if not result:
self._conn.detach_x11_listener(self)
raise ChannelOpenError(OPEN_REQUEST_X11_FORWARDING_FAILED,
'X11 forwarding request failed')
if agent_forwarding:
self._send_request(b'auth-agent-req@openssh.com')
if command:
result = yield from self._make_request(b'exec', String(command))
elif subsystem:
result = yield from self._make_request(b'subsystem',
String(subsystem))
else:
result = yield from self._make_request(b'shell')
if not result:
self.close()
raise ChannelOpenError(OPEN_REQUEST_SESSION_FAILED,
'Session request failed')
self._session.session_started()
self.resume_reading()
return self, self._session
def _process_xon_xoff_request(self, packet):
"""Process a request to set up XON/XOFF processing"""
client_can_do = packet.get_boolean()
packet.check_end()
self._session.xon_xoff_requested(client_can_do)
return True
def _process_exit_status_request(self, packet):
"""Process a request to deliver exit status"""
status = packet.get_uint32() & 0xff
packet.check_end()
self._exit_status = status
self._session.exit_status_received(status)
return True
def _process_exit_signal_request(self, packet):
"""Process a request to deliver an exit signal"""
signal = packet.get_string()
core_dumped = packet.get_boolean()
msg = packet.get_string()
lang = packet.get_string()
packet.check_end()
try:
signal = signal.decode('ascii')
msg = msg.decode('utf-8')
lang = lang.decode('ascii')
except UnicodeDecodeError:
raise DisconnectError(DISC_PROTOCOL_ERROR,
'Invalid exit signal request') from None
self._exit_signal = (signal, core_dumped, msg, lang)
self._session.exit_signal_received(signal, core_dumped, msg, lang)
return True
def get_exit_status(self):
"""Return the session's exit status
This method returns the exit status of the session if one has
been sent. If an exit signal was received, this method
returns -1 and the exit signal information can be collected
by calling :meth:`get_exit_signal`. If neither has been sent,
this method returns ``None``.
"""
if self._exit_status is not None:
return self._exit_status
elif self._exit_signal:
return -1
else:
return None
def get_exit_signal(self):
"""Return the session's exit signal, if one was sent
This method returns information about the exit signal sent on
this session. If an exit signal was sent, a tuple is returned
containing the signal name, a boolean for whether a core dump
occurred, a message associated with the signal, and the language
the message was in. If no exit signal was sent, ``None`` is
returned.
"""
return self._exit_signal
def change_terminal_size(self, width, height, pixwidth=0, pixheight=0):
"""Change the terminal window size for this session
This method changes the width and height of the terminal
associated with this session.
:param int width:
The width of the terminal in characters
:param int height:
The height of the terminal in characters
:param int pixwidth: (optional)
The width of the terminal in pixels
:param int pixheight: (optional)
The height of the terminal in pixels
"""
self._send_request(b'window-change', UInt32(width), UInt32(height),
UInt32(pixwidth), UInt32(pixheight))
def send_break(self, msec):
"""Send a break to the remote process
This method requests that the server perform a break
operation on the remote process or service as described in
:rfc:`4335`.
:param int msec:
The duration of the break in milliseconds
:raises: :exc:`OSError` if the channel is not open
"""
self._send_request(b'break', UInt32(msec))
def send_signal(self, signal):
"""Send a signal to the remote process
This method can be called to deliver a signal to the remote
process or service. Signal names should be as described in
section 6.10 of :rfc:`RFC 4254 <4254#section-6.10>`.
.. note:: OpenSSH's SSH server implementation does not
currently support this message, so attempts to
use :meth:`send_signal`, :meth:`terminate`, or
:meth:`kill` with an OpenSSH SSH server will
end up being ignored. This is currently being
tracked in OpenSSH `bug 1424`__.
__ https://bugzilla.mindrot.org/show_bug.cgi?id=1424
:param str signal:
The signal to deliver
:raises: :exc:`OSError` if the channel is not open
"""
self._send_request(b'signal', String(signal))
def terminate(self):
"""Terminate the remote process
This method can be called to terminate the remote process or
service by sending it a ``TERM`` signal.
:raises: :exc:`OSError` if the channel is not open
"""
self.send_signal('TERM')
def kill(self):
"""Forcibly kill the remote process
This method can be called to forcibly stop the remote process
or service by sending it a ``KILL`` signal.
:raises: :exc:`OSError` if the channel is not open
"""
self.send_signal('KILL')
class SSHServerChannel(SSHChannel):
"""SSH server channel"""
_write_datatypes = {EXTENDED_DATA_STDERR}
def __init__(self, conn, loop, allow_pty, line_editor, line_history,
encoding, window, max_pktsize):
"""Initialize an SSH server channel"""
super().__init__(conn, loop, encoding, window, max_pktsize)
self._env = conn.get_key_option('environment', {})
self._allow_pty = allow_pty
self._line_editor = line_editor
self._line_history = line_history
self._term_type = None
self._term_size = (0, 0, 0, 0)
self._term_modes = {}
self._x11_display = None
def _cleanup(self, exc=None):
"""Clean up this channel"""
self._conn.detach_x11_listener(self)
super()._cleanup(exc)
def _wrap_session(self, session):
"""Wrap a line editor around the session if enabled"""
if self._line_editor:
chan = SSHLineEditorChannel(self, session, self._line_history)
session = SSHLineEditorSession(chan, session)
else:
chan = self
return chan, session
def _process_pty_req_request(self, packet):
"""Process a request to open a pseudo-terminal"""
term_type = packet.get_string()
width = packet.get_uint32()
height = packet.get_uint32()
pixwidth = packet.get_uint32()
pixheight = packet.get_uint32()
modes = packet.get_string()
packet.check_end()
if not self._allow_pty or \
not self._conn.check_key_permission('pty') or \
not self._conn.check_certificate_permission('pty'):
return False
try:
term_type = term_type.decode('ascii')
except UnicodeDecodeError:
raise DisconnectError(DISC_PROTOCOL_ERROR,
'Invalid pty request') from None
term_size = (width, height, pixwidth, pixheight)
term_modes = {}
idx = 0
while idx < len(modes):
mode = modes[idx]
idx += 1
if mode == PTY_OP_END or mode >= PTY_OP_RESERVED:
break
if idx+4 <= len(modes):
term_modes[mode] = int.from_bytes(modes[idx:idx+4], 'big')
idx += 4
else:
raise DisconnectError(DISC_PROTOCOL_ERROR,
'Invalid pty modes string')
result = self._session.pty_requested(self._term_type, self._term_size,
self._term_modes)
if result:
self._term_type = term_type
self._term_size = term_size
self._term_modes = term_modes
return result
def _process_x11_req_request(self, packet):
"""Process request to enable X11 forwarding"""
_ = packet.get_boolean() # single_connection
auth_proto = packet.get_string()
auth_data = packet.get_string()
screen = packet.get_uint32()
packet.check_end()
try:
auth_data = binascii.a2b_hex(auth_data)
except binascii.Error:
return False
self._conn.create_task(self._finish_x11_req_request(auth_proto,
auth_data, screen))
@asyncio.coroutine
def _finish_x11_req_request(self, auth_proto, auth_data, screen):
"""Finish processing request to enable X11 forwarding"""
self._x11_display = yield from self._conn.attach_x11_listener(
self, auth_proto, auth_data, screen)
self._report_response(bool(self._x11_display))
def _process_auth_agent_req_at_openssh_dot_com_request(self, packet):
"""Process a request to enable ssh-agent forwarding"""
packet.check_end()
self._conn.create_task(self._finish_agent_req_request())
@asyncio.coroutine
def _finish_agent_req_request(self):
"""Finish processing request to enable agent forwarding"""
self._report_response((yield from self._conn.create_agent_listener()))
def _process_env_request(self, packet):
"""Process a request to set an environment variable"""
name = packet.get_string()
value = packet.get_string()
packet.check_end()
try:
name = name.decode('utf-8')
value = value.decode('utf-8')
except UnicodeDecodeError:
return False
self._env[name] = value
return True
def _start_session(self, command=None, subsystem=None):
"""Tell the session what type of channel is being requested"""
forced_command = self._conn.get_certificate_option('force-command')
if forced_command is None:
forced_command = self._conn.get_key_option('command')
if forced_command is not None:
command = forced_command
if command is not None:
self._command = command
result = self._session.exec_requested(command)
elif subsystem is not None:
self._subsystem = subsystem
result = self._session.subsystem_requested(subsystem)
else:
result = self._session.shell_requested()
return result
def _process_shell_request(self, packet):
"""Process a request to open a shell"""
packet.check_end()
return self._start_session()
def _process_exec_request(self, packet):
"""Process a request to execute a command"""
command = packet.get_string()
packet.check_end()
try:
command = command.decode('utf-8')
except UnicodeDecodeError:
return False
return self._start_session(command=command)
def _process_subsystem_request(self, packet):
"""Process a request to open a subsystem"""
subsystem = packet.get_string()
packet.check_end()
try:
subsystem = subsystem.decode('ascii')
except UnicodeDecodeError:
return False
return self._start_session(subsystem=subsystem)
def _process_window_change_request(self, packet):
"""Process a request to change the window size"""
width = packet.get_uint32()
height = packet.get_uint32()
pixwidth = packet.get_uint32()
pixheight = packet.get_uint32()
packet.check_end()
self._term_size = (width, height, pixwidth, pixheight)
self._session.terminal_size_changed(width, height, pixwidth, pixheight)
return True
def _process_signal_request(self, packet):
"""Process a request to send a signal"""
signal = packet.get_string()
packet.check_end()
try:
signal = signal.decode('ascii')
except UnicodeDecodeError:
return False
self._session.signal_received(signal)
return True
def _process_break_request(self, packet):
"""Process a request to send a break"""
msec = packet.get_uint32()
packet.check_end()
return self._session.break_received(msec)
def get_terminal_type(self):
"""Return the terminal type for this session
This method returns the terminal type set by the client
when the session was opened. If the client didn't request
a pseudo-terminal, this method will return ``None``. Calls
to this method should only be made after :meth:`session_started
<SSHServerSession.session_started>` has been called on the
:class:`SSHServerSession`. When using the stream-based API,
calls to this can be made at any time after the handler
function has started up.
:returns: A str containing the terminal type or ``None`` if
no pseudo-terminal was requested
"""
return self._term_type
def get_terminal_size(self):
"""Return terminal size information for this session
This method returns the latest terminal size information set
by the client. If the client didn't set any terminal size
information, all values returned will be zero. Calls to
this method should only be made after :meth:`session_started
<SSHServerSession.session_started>` has been called on the
:class:`SSHServerSession`. When using the stream-based API,
calls to this can be made at any time after the handler
function has started up.
Also see :meth:`terminal_size_changed()
<SSHServerSession.terminal_size_changed>` or the
:exc:`TerminalSizeChanged` exception for how to get notified
when the terminal size changes.
:returns: A tuple of four integers containing the width and
height of the terminal in characters and the width
and height of the terminal in pixels
"""
return self._term_size
def get_terminal_mode(self, mode):
"""Return the requested TTY mode for this session
This method looks up the value of a POSIX terminal mode
set by the client when the session was opened. If the client
didn't request a pseudo-terminal or didn't set the requested
TTY mode opcode, this method will return ``None``. Calls to
this method should only be made after :meth:`session_started
<SSHServerSession.session_started>` has been called on the
:class:`SSHServerSession`. When using the stream-based API,
calls to this can be made at any time after the handler
function has started up.
:param int mode:
POSIX terminal mode taken from :ref:`POSIX terminal modes
<PTYModes>` to look up
:returns: An int containing the value of the requested
POSIX terminal mode or ``None`` if the requested
mode was not set
"""
return self._term_modes.get(mode)
def get_x11_display(self):
"""Return the display to use for X11 forwarding
When X11 forwarding has been requested by the client, this
method returns the X11 display which should be used to open
a forwarded connection. If the client did not request X11
forwarding, this method returns ``None``.
:returns: A str containing the X11 display or ``None`` if
X11 fowarding was not requested
"""
return self._x11_display
def get_agent_path(self):
"""Return the path of the ssh-agent listening socket
When agent forwarding has been requested by the client,
this method returns the path of the listening socket which
should be used to open a forwarded agent connection. If the
client did not request agent forwarding, this method returns
``None``.
:returns: A str containing the ssh-agent socket path or
``None`` if agent fowarding was not requested
"""
return self._conn.get_agent_path()
def set_xon_xoff(self, client_can_do):
"""Set whether the client should enable XON/XOFF flow control
This method can be called to tell the client whether or not
to enable XON/XOFF flow control, indicating that it should
intercept Control-S and Control-Q coming from its local
terminal to pause and resume output, respectively.
Applications should set client_can_do to ``True`` to
enable this functionality or to ``False`` to tell the client
to forward Control-S and Control-Q through as normal input.
:param bool client_can_do:
Whether or not the client should enable XON/XOFF flow control
"""
self._send_request(b'xon-xoff', Boolean(client_can_do))
def write_stderr(self, data):
"""Write output to stderr
This method can be called to send output to the client which
is intended to be displayed on stderr. If an encoding was
specified when the channel was created, the data should be
provided as a string and will be converted using that
encoding. Otherwise, the data should be provided as bytes.
:param data:
The data to send to stderr
:type data: str or bytes
:raises: :exc:`OSError` if the channel isn't open for sending
"""
self.write(data, EXTENDED_DATA_STDERR)
def writelines_stderr(self, list_of_data):
"""Write a list of data bytes to stderr
This method can be called to write a list (or any iterable) of
data bytes to the channel. It is functionality equivalent to
calling :meth:`write_stderr` on each element in the list.
"""
self.writelines(list_of_data, EXTENDED_DATA_STDERR)
def exit(self, status):
"""Send exit status and close the channel
This method can be called to report an exit status for the
process back to the client and close the channel. A zero
exit status is generally returned when the operation was
successful. After reporting the status, the channel is
closed.
:param int status:
The exit status to report to the client
:raises: :exc:`OSError` if the channel isn't open
"""
if self._send_state not in {'close_pending', 'closed'}:
self._send_request(b'exit-status', UInt32(status & 0xff))
self.close()
def exit_with_signal(self, signal, core_dumped=False,
msg='', lang=DEFAULT_LANG):
"""Send exit signal and close the channel
This method can be called to report that the process
terminated abnormslly with a signal. A more detailed
error message may also provided, along with an indication
of whether or not the process dumped core. After
reporting the signal, the channel is closed.
:param str signal:
The signal which caused the process to exit
:param bool core_dumped: (optional)
Whether or not the process dumped core
:param str msg: (optional)
Details about what error occurred
:param str lang: (optional)
The language the error message is in
:raises: :exc:`OSError` if the channel isn't open
"""
if self._send_state not in {'close_pending', 'closed'}:
self._send_request(b'exit-signal', String(signal),
Boolean(core_dumped), String(msg), String(lang))
self.close()
class SSHForwardChannel(SSHChannel):
"""SSH channel for forwarding TCP and UNIX domain connections"""
@asyncio.coroutine
def _finish_open_request(self, session):
"""Finish processing a forward channel open request"""
yield from super()._finish_open_request(session)
if self._session:
self._session.session_started()
self.resume_reading()
@asyncio.coroutine
def _open(self, session_factory, chantype, *args):
"""Open a forward channel"""
packet = yield from super()._open(chantype, *args)
# Forward channels should have no extra data in the open confirmation
packet.check_end()
self._session = session_factory()
self._session.connection_made(self)
self._session.session_started()
self.resume_reading()
return self._session
class SSHTCPChannel(SSHForwardChannel):
"""SSH TCP channel"""
@asyncio.coroutine
def _open_tcp(self, session_factory, chantype, host, port,
orig_host, orig_port):
"""Open a TCP channel"""
self._extra['peername'] = None
self._extra['local_peername'] = (orig_host, orig_port)
self._extra['remote_peername'] = (host, port)
return (yield from super()._open(session_factory, chantype,
String(host), UInt32(port),
String(orig_host), UInt32(orig_port)))
@asyncio.coroutine
def connect(self, session_factory, host, port, orig_host, orig_port):
"""Create a new outbound TCP session"""
return (yield from self._open_tcp(session_factory, b'direct-tcpip',
host, port, orig_host, orig_port))
@asyncio.coroutine
def accept(self, session_factory, host, port, orig_host, orig_port):
"""Create a new forwarded TCP session"""
return (yield from self._open_tcp(session_factory, b'forwarded-tcpip',
host, port, orig_host, orig_port))
def set_inbound_peer_names(self, dest_host, dest_port,
orig_host, orig_port):
"""Set local and remote peer names for inbound connections"""
self._extra['local_peername'] = (dest_host, dest_port)
self._extra['remote_peername'] = (orig_host, orig_port)
class SSHUNIXChannel(SSHForwardChannel):
"""SSH UNIX channel"""
@asyncio.coroutine
def _open_unix(self, session_factory, chantype, path, *args):
"""Open a UNIX channel"""
self._extra['local_peername'] = ''
self._extra['remote_peername'] = path
return (yield from super()._open(session_factory, chantype,
String(path), *args))
@asyncio.coroutine
def connect(self, session_factory, path):
"""Create a new outbound UNIX session"""
# OpenSSH appears to have a bug which requires an originator
# host and port to be sent after the path name to connect to
# when opening a direct streamlocal channel.
return (yield from self._open_unix(session_factory,
b'direct-streamlocal@openssh.com',
path, String(''), UInt32(0)))
@asyncio.coroutine
def accept(self, session_factory, path):
"""Create a new forwarded UNIX session"""
return (yield from self._open_unix(session_factory,
b'forwarded-streamlocal@openssh.com',
path, String('')))
def set_inbound_peer_names(self, dest_path):
"""Set local and remote peer names for inbound connections"""
self._extra['local_peername'] = dest_path
self._extra['remote_peername'] = ''
class SSHX11Channel(SSHForwardChannel):
"""SSH X11 channel"""
@asyncio.coroutine
def open(self, session_factory, orig_host, orig_port):
"""Open an SSH X11 channel"""
self._extra['local_peername'] = (orig_host, orig_port)
self._extra['remote_peername'] = None
return (yield from self._open(session_factory, b'x11',
String(orig_host), UInt32(orig_port)))
def set_inbound_peer_names(self, orig_host, orig_port):
"""Set local and remote peer name for inbound connections"""
self._extra['local_peername'] = None
self._extra['remote_peername'] = (orig_host, orig_port)
class SSHAgentChannel(SSHForwardChannel):
"""SSH agent channel"""
@asyncio.coroutine
def open(self, session_factory):
"""Open an SSH agent channel"""
return (yield from self._open(session_factory,
b'auth-agent@openssh.com'))
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