Current File : //lib/python3/dist-packages/twisted/conch/ssh/connection.py
# -*- test-case-name: twisted.conch.test.test_connection -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
This module contains the implementation of the ssh-connection service, which
allows access to the shell and port-forwarding.
Maintainer: Paul Swartz
"""
import string
import struct
import twisted.internet.error
from twisted.conch import error
from twisted.conch.ssh import common, service
from twisted.internet import defer
from twisted.logger import Logger
from twisted.python.compat import nativeString, networkString
class SSHConnection(service.SSHService):
"""
An implementation of the 'ssh-connection' service. It is used to
multiplex multiple channels over the single SSH connection.
@ivar localChannelID: the next number to use as a local channel ID.
@type localChannelID: L{int}
@ivar channels: a L{dict} mapping a local channel ID to C{SSHChannel}
subclasses.
@type channels: L{dict}
@ivar localToRemoteChannel: a L{dict} mapping a local channel ID to a
remote channel ID.
@type localToRemoteChannel: L{dict}
@ivar channelsToRemoteChannel: a L{dict} mapping a C{SSHChannel} subclass
to remote channel ID.
@type channelsToRemoteChannel: L{dict}
@ivar deferreds: a L{dict} mapping a local channel ID to a C{list} of
C{Deferreds} for outstanding channel requests. Also, the 'global'
key stores the C{list} of pending global request C{Deferred}s.
"""
name = b"ssh-connection"
_log = Logger()
def __init__(self):
self.localChannelID = 0 # this is the current # to use for channel ID
# local channel ID -> remote channel ID
self.localToRemoteChannel = {}
# local channel ID -> subclass of SSHChannel
self.channels = {}
# subclass of SSHChannel -> remote channel ID
self.channelsToRemoteChannel = {}
# local channel -> list of deferreds for pending requests
# or 'global' -> list of deferreds for global requests
self.deferreds = {"global": []}
self.transport = None # gets set later
def serviceStarted(self):
if hasattr(self.transport, "avatar"):
self.transport.avatar.conn = self
def serviceStopped(self):
"""
Called when the connection is stopped.
"""
# Close any fully open channels
for channel in list(self.channelsToRemoteChannel.keys()):
self.channelClosed(channel)
# Indicate failure to any channels that were in the process of
# opening but not yet open.
while self.channels:
(_, channel) = self.channels.popitem()
channel.openFailed(twisted.internet.error.ConnectionLost())
# Errback any unfinished global requests.
self._cleanupGlobalDeferreds()
def _cleanupGlobalDeferreds(self):
"""
All pending requests that have returned a deferred must be errbacked
when this service is stopped, otherwise they might be left uncalled and
uncallable.
"""
for d in self.deferreds["global"]:
d.errback(error.ConchError("Connection stopped."))
del self.deferreds["global"][:]
# packet methods
def ssh_GLOBAL_REQUEST(self, packet):
"""
The other side has made a global request. Payload::
string request type
bool want reply
<request specific data>
This dispatches to self.gotGlobalRequest.
"""
requestType, rest = common.getNS(packet)
wantReply, rest = ord(rest[0:1]), rest[1:]
ret = self.gotGlobalRequest(requestType, rest)
if wantReply:
reply = MSG_REQUEST_FAILURE
data = b""
if ret:
reply = MSG_REQUEST_SUCCESS
if isinstance(ret, (tuple, list)):
data = ret[1]
self.transport.sendPacket(reply, data)
def ssh_REQUEST_SUCCESS(self, packet):
"""
Our global request succeeded. Get the appropriate Deferred and call
it back with the packet we received.
"""
self._log.debug("global request success")
self.deferreds["global"].pop(0).callback(packet)
def ssh_REQUEST_FAILURE(self, packet):
"""
Our global request failed. Get the appropriate Deferred and errback
it with the packet we received.
"""
self._log.debug("global request failure")
self.deferreds["global"].pop(0).errback(
error.ConchError("global request failed", packet)
)
def ssh_CHANNEL_OPEN(self, packet):
"""
The other side wants to get a channel. Payload::
string channel name
uint32 remote channel number
uint32 remote window size
uint32 remote maximum packet size
<channel specific data>
We get a channel from self.getChannel(), give it a local channel number
and notify the other side. Then notify the channel by calling its
channelOpen method.
"""
channelType, rest = common.getNS(packet)
senderChannel, windowSize, maxPacket = struct.unpack(">3L", rest[:12])
packet = rest[12:]
try:
channel = self.getChannel(channelType, windowSize, maxPacket, packet)
localChannel = self.localChannelID
self.localChannelID += 1
channel.id = localChannel
self.channels[localChannel] = channel
self.channelsToRemoteChannel[channel] = senderChannel
self.localToRemoteChannel[localChannel] = senderChannel
openConfirmPacket = (
struct.pack(
">4L",
senderChannel,
localChannel,
channel.localWindowSize,
channel.localMaxPacket,
)
+ channel.specificData
)
self.transport.sendPacket(MSG_CHANNEL_OPEN_CONFIRMATION, openConfirmPacket)
channel.channelOpen(packet)
except Exception as e:
self._log.failure("channel open failed")
if isinstance(e, error.ConchError):
textualInfo, reason = e.args
if isinstance(textualInfo, int):
# See #3657 and #3071
textualInfo, reason = reason, textualInfo
else:
reason = OPEN_CONNECT_FAILED
textualInfo = "unknown failure"
self.transport.sendPacket(
MSG_CHANNEL_OPEN_FAILURE,
struct.pack(">2L", senderChannel, reason)
+ common.NS(networkString(textualInfo))
+ common.NS(b""),
)
def ssh_CHANNEL_OPEN_CONFIRMATION(self, packet):
"""
The other side accepted our MSG_CHANNEL_OPEN request. Payload::
uint32 local channel number
uint32 remote channel number
uint32 remote window size
uint32 remote maximum packet size
<channel specific data>
Find the channel using the local channel number and notify its
channelOpen method.
"""
(localChannel, remoteChannel, windowSize, maxPacket) = struct.unpack(
">4L", packet[:16]
)
specificData = packet[16:]
channel = self.channels[localChannel]
channel.conn = self
self.localToRemoteChannel[localChannel] = remoteChannel
self.channelsToRemoteChannel[channel] = remoteChannel
channel.remoteWindowLeft = windowSize
channel.remoteMaxPacket = maxPacket
channel.channelOpen(specificData)
def ssh_CHANNEL_OPEN_FAILURE(self, packet):
"""
The other side did not accept our MSG_CHANNEL_OPEN request. Payload::
uint32 local channel number
uint32 reason code
string reason description
Find the channel using the local channel number and notify it by
calling its openFailed() method.
"""
localChannel, reasonCode = struct.unpack(">2L", packet[:8])
reasonDesc = common.getNS(packet[8:])[0]
channel = self.channels[localChannel]
del self.channels[localChannel]
channel.conn = self
reason = error.ConchError(reasonDesc, reasonCode)
channel.openFailed(reason)
def ssh_CHANNEL_WINDOW_ADJUST(self, packet):
"""
The other side is adding bytes to its window. Payload::
uint32 local channel number
uint32 bytes to add
Call the channel's addWindowBytes() method to add new bytes to the
remote window.
"""
localChannel, bytesToAdd = struct.unpack(">2L", packet[:8])
channel = self.channels[localChannel]
channel.addWindowBytes(bytesToAdd)
def ssh_CHANNEL_DATA(self, packet):
"""
The other side is sending us data. Payload::
uint32 local channel number
string data
Check to make sure the other side hasn't sent too much data (more
than what's in the window, or more than the maximum packet size). If
they have, close the channel. Otherwise, decrease the available
window and pass the data to the channel's dataReceived().
"""
localChannel, dataLength = struct.unpack(">2L", packet[:8])
channel = self.channels[localChannel]
# XXX should this move to dataReceived to put client in charge?
if (
dataLength > channel.localWindowLeft or dataLength > channel.localMaxPacket
): # more data than we want
self._log.error("too much data")
self.sendClose(channel)
return
# packet = packet[:channel.localWindowLeft+4]
data = common.getNS(packet[4:])[0]
channel.localWindowLeft -= dataLength
if channel.localWindowLeft < channel.localWindowSize // 2:
self.adjustWindow(
channel, channel.localWindowSize - channel.localWindowLeft
)
channel.dataReceived(data)
def ssh_CHANNEL_EXTENDED_DATA(self, packet):
"""
The other side is sending us exteneded data. Payload::
uint32 local channel number
uint32 type code
string data
Check to make sure the other side hasn't sent too much data (more
than what's in the window, or than the maximum packet size). If
they have, close the channel. Otherwise, decrease the available
window and pass the data and type code to the channel's
extReceived().
"""
localChannel, typeCode, dataLength = struct.unpack(">3L", packet[:12])
channel = self.channels[localChannel]
if dataLength > channel.localWindowLeft or dataLength > channel.localMaxPacket:
self._log.error("too much extdata")
self.sendClose(channel)
return
data = common.getNS(packet[8:])[0]
channel.localWindowLeft -= dataLength
if channel.localWindowLeft < channel.localWindowSize // 2:
self.adjustWindow(
channel, channel.localWindowSize - channel.localWindowLeft
)
channel.extReceived(typeCode, data)
def ssh_CHANNEL_EOF(self, packet):
"""
The other side is not sending any more data. Payload::
uint32 local channel number
Notify the channel by calling its eofReceived() method.
"""
localChannel = struct.unpack(">L", packet[:4])[0]
channel = self.channels[localChannel]
channel.eofReceived()
def ssh_CHANNEL_CLOSE(self, packet):
"""
The other side is closing its end; it does not want to receive any
more data. Payload::
uint32 local channel number
Notify the channnel by calling its closeReceived() method. If
the channel has also sent a close message, call self.channelClosed().
"""
localChannel = struct.unpack(">L", packet[:4])[0]
channel = self.channels[localChannel]
channel.closeReceived()
channel.remoteClosed = True
if channel.localClosed and channel.remoteClosed:
self.channelClosed(channel)
def ssh_CHANNEL_REQUEST(self, packet):
"""
The other side is sending a request to a channel. Payload::
uint32 local channel number
string request name
bool want reply
<request specific data>
Pass the message to the channel's requestReceived method. If the
other side wants a reply, add callbacks which will send the
reply.
"""
localChannel = struct.unpack(">L", packet[:4])[0]
requestType, rest = common.getNS(packet[4:])
wantReply = ord(rest[0:1])
channel = self.channels[localChannel]
d = defer.maybeDeferred(channel.requestReceived, requestType, rest[1:])
if wantReply:
d.addCallback(self._cbChannelRequest, localChannel)
d.addErrback(self._ebChannelRequest, localChannel)
return d
def _cbChannelRequest(self, result, localChannel):
"""
Called back if the other side wanted a reply to a channel request. If
the result is true, send a MSG_CHANNEL_SUCCESS. Otherwise, raise
a C{error.ConchError}
@param result: the value returned from the channel's requestReceived()
method. If it's False, the request failed.
@type result: L{bool}
@param localChannel: the local channel ID of the channel to which the
request was made.
@type localChannel: L{int}
@raises ConchError: if the result is False.
"""
if not result:
raise error.ConchError("failed request")
self.transport.sendPacket(
MSG_CHANNEL_SUCCESS,
struct.pack(">L", self.localToRemoteChannel[localChannel]),
)
def _ebChannelRequest(self, result, localChannel):
"""
Called if the other wisde wanted a reply to the channel requeset and
the channel request failed.
@param result: a Failure, but it's not used.
@param localChannel: the local channel ID of the channel to which the
request was made.
@type localChannel: L{int}
"""
self.transport.sendPacket(
MSG_CHANNEL_FAILURE,
struct.pack(">L", self.localToRemoteChannel[localChannel]),
)
def ssh_CHANNEL_SUCCESS(self, packet):
"""
Our channel request to the other side succeeded. Payload::
uint32 local channel number
Get the C{Deferred} out of self.deferreds and call it back.
"""
localChannel = struct.unpack(">L", packet[:4])[0]
if self.deferreds.get(localChannel):
d = self.deferreds[localChannel].pop(0)
d.callback("")
def ssh_CHANNEL_FAILURE(self, packet):
"""
Our channel request to the other side failed. Payload::
uint32 local channel number
Get the C{Deferred} out of self.deferreds and errback it with a
C{error.ConchError}.
"""
localChannel = struct.unpack(">L", packet[:4])[0]
if self.deferreds.get(localChannel):
d = self.deferreds[localChannel].pop(0)
d.errback(error.ConchError("channel request failed"))
# methods for users of the connection to call
def sendGlobalRequest(self, request, data, wantReply=0):
"""
Send a global request for this connection. Current this is only used
for remote->local TCP forwarding.
@type request: L{bytes}
@type data: L{bytes}
@type wantReply: L{bool}
@rtype: C{Deferred}/L{None}
"""
self.transport.sendPacket(
MSG_GLOBAL_REQUEST,
common.NS(request) + (wantReply and b"\xff" or b"\x00") + data,
)
if wantReply:
d = defer.Deferred()
self.deferreds["global"].append(d)
return d
def openChannel(self, channel, extra=b""):
"""
Open a new channel on this connection.
@type channel: subclass of C{SSHChannel}
@type extra: L{bytes}
"""
self._log.info(
"opening channel {id} with {localWindowSize} {localMaxPacket}",
id=self.localChannelID,
localWindowSize=channel.localWindowSize,
localMaxPacket=channel.localMaxPacket,
)
self.transport.sendPacket(
MSG_CHANNEL_OPEN,
common.NS(channel.name)
+ struct.pack(
">3L",
self.localChannelID,
channel.localWindowSize,
channel.localMaxPacket,
)
+ extra,
)
channel.id = self.localChannelID
self.channels[self.localChannelID] = channel
self.localChannelID += 1
def sendRequest(self, channel, requestType, data, wantReply=0):
"""
Send a request to a channel.
@type channel: subclass of C{SSHChannel}
@type requestType: L{bytes}
@type data: L{bytes}
@type wantReply: L{bool}
@rtype: C{Deferred}/L{None}
"""
if channel.localClosed:
return
self._log.debug("sending request {requestType}", requestType=requestType)
self.transport.sendPacket(
MSG_CHANNEL_REQUEST,
struct.pack(">L", self.channelsToRemoteChannel[channel])
+ common.NS(requestType)
+ (b"\1" if wantReply else b"\0")
+ data,
)
if wantReply:
d = defer.Deferred()
self.deferreds.setdefault(channel.id, []).append(d)
return d
def adjustWindow(self, channel, bytesToAdd):
"""
Tell the other side that we will receive more data. This should not
normally need to be called as it is managed automatically.
@type channel: subclass of L{SSHChannel}
@type bytesToAdd: L{int}
"""
if channel.localClosed:
return # we're already closed
packet = struct.pack(">2L", self.channelsToRemoteChannel[channel], bytesToAdd)
self.transport.sendPacket(MSG_CHANNEL_WINDOW_ADJUST, packet)
self._log.debug(
"adding {bytesToAdd} to {localWindowLeft} in channel {id}",
bytesToAdd=bytesToAdd,
localWindowLeft=channel.localWindowLeft,
id=channel.id,
)
channel.localWindowLeft += bytesToAdd
def sendData(self, channel, data):
"""
Send data to a channel. This should not normally be used: instead use
channel.write(data) as it manages the window automatically.
@type channel: subclass of L{SSHChannel}
@type data: L{bytes}
"""
if channel.localClosed:
return # we're already closed
self.transport.sendPacket(
MSG_CHANNEL_DATA,
struct.pack(">L", self.channelsToRemoteChannel[channel]) + common.NS(data),
)
def sendExtendedData(self, channel, dataType, data):
"""
Send extended data to a channel. This should not normally be used:
instead use channel.writeExtendedData(data, dataType) as it manages
the window automatically.
@type channel: subclass of L{SSHChannel}
@type dataType: L{int}
@type data: L{bytes}
"""
if channel.localClosed:
return # we're already closed
self.transport.sendPacket(
MSG_CHANNEL_EXTENDED_DATA,
struct.pack(">2L", self.channelsToRemoteChannel[channel], dataType)
+ common.NS(data),
)
def sendEOF(self, channel):
"""
Send an EOF (End of File) for a channel.
@type channel: subclass of L{SSHChannel}
"""
if channel.localClosed:
return # we're already closed
self._log.debug("sending eof")
self.transport.sendPacket(
MSG_CHANNEL_EOF, struct.pack(">L", self.channelsToRemoteChannel[channel])
)
def sendClose(self, channel):
"""
Close a channel.
@type channel: subclass of L{SSHChannel}
"""
if channel.localClosed:
return # we're already closed
self._log.info("sending close {id}", id=channel.id)
self.transport.sendPacket(
MSG_CHANNEL_CLOSE, struct.pack(">L", self.channelsToRemoteChannel[channel])
)
channel.localClosed = True
if channel.localClosed and channel.remoteClosed:
self.channelClosed(channel)
# methods to override
def getChannel(self, channelType, windowSize, maxPacket, data):
"""
The other side requested a channel of some sort.
channelType is the type of channel being requested,
windowSize is the initial size of the remote window,
maxPacket is the largest packet we should send,
data is any other packet data (often nothing).
We return a subclass of L{SSHChannel}.
By default, this dispatches to a method 'channel_channelType' with any
non-alphanumerics in the channelType replace with _'s. If it cannot
find a suitable method, it returns an OPEN_UNKNOWN_CHANNEL_TYPE error.
The method is called with arguments of windowSize, maxPacket, data.
@type channelType: L{bytes}
@type windowSize: L{int}
@type maxPacket: L{int}
@type data: L{bytes}
@rtype: subclass of L{SSHChannel}/L{tuple}
"""
self._log.debug("got channel {channelType!r} request", channelType=channelType)
if hasattr(self.transport, "avatar"): # this is a server!
chan = self.transport.avatar.lookupChannel(
channelType, windowSize, maxPacket, data
)
else:
channelType = channelType.translate(TRANSLATE_TABLE)
attr = "channel_%s" % nativeString(channelType)
f = getattr(self, attr, None)
if f is not None:
chan = f(windowSize, maxPacket, data)
else:
chan = None
if chan is None:
raise error.ConchError("unknown channel", OPEN_UNKNOWN_CHANNEL_TYPE)
else:
chan.conn = self
return chan
def gotGlobalRequest(self, requestType, data):
"""
We got a global request. pretty much, this is just used by the client
to request that we forward a port from the server to the client.
Returns either:
- 1: request accepted
- 1, <data>: request accepted with request specific data
- 0: request denied
By default, this dispatches to a method 'global_requestType' with
-'s in requestType replaced with _'s. The found method is passed data.
If this method cannot be found, this method returns 0. Otherwise, it
returns the return value of that method.
@type requestType: L{bytes}
@type data: L{bytes}
@rtype: L{int}/L{tuple}
"""
self._log.debug("got global {requestType} request", requestType=requestType)
if hasattr(self.transport, "avatar"): # this is a server!
return self.transport.avatar.gotGlobalRequest(requestType, data)
requestType = nativeString(requestType.replace(b"-", b"_"))
f = getattr(self, "global_%s" % requestType, None)
if not f:
return 0
return f(data)
def channelClosed(self, channel):
"""
Called when a channel is closed.
It clears the local state related to the channel, and calls
channel.closed().
MAKE SURE YOU CALL THIS METHOD, even if you subclass L{SSHConnection}.
If you don't, things will break mysteriously.
@type channel: L{SSHChannel}
"""
if channel in self.channelsToRemoteChannel: # actually open
channel.localClosed = channel.remoteClosed = True
del self.localToRemoteChannel[channel.id]
del self.channels[channel.id]
del self.channelsToRemoteChannel[channel]
for d in self.deferreds.pop(channel.id, []):
d.errback(error.ConchError("Channel closed."))
channel.closed()
MSG_GLOBAL_REQUEST = 80
MSG_REQUEST_SUCCESS = 81
MSG_REQUEST_FAILURE = 82
MSG_CHANNEL_OPEN = 90
MSG_CHANNEL_OPEN_CONFIRMATION = 91
MSG_CHANNEL_OPEN_FAILURE = 92
MSG_CHANNEL_WINDOW_ADJUST = 93
MSG_CHANNEL_DATA = 94
MSG_CHANNEL_EXTENDED_DATA = 95
MSG_CHANNEL_EOF = 96
MSG_CHANNEL_CLOSE = 97
MSG_CHANNEL_REQUEST = 98
MSG_CHANNEL_SUCCESS = 99
MSG_CHANNEL_FAILURE = 100
OPEN_ADMINISTRATIVELY_PROHIBITED = 1
OPEN_CONNECT_FAILED = 2
OPEN_UNKNOWN_CHANNEL_TYPE = 3
OPEN_RESOURCE_SHORTAGE = 4
# From RFC 4254
EXTENDED_DATA_STDERR = 1
messages = {}
for name, value in locals().copy().items():
if name[:4] == "MSG_":
messages[value] = name # Doesn't handle doubles
alphanums = networkString(string.ascii_letters + string.digits)
TRANSLATE_TABLE = bytes(i if i in alphanums else ord("_") for i in range(256))
SSHConnection.protocolMessages = messages
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