# Twisted, the Framework of Your Internet # Copyright (C) 2001-2002 Matthew W. Lefkowitz # # This library is free software; you can redistribute it and/or # modify it under the terms of version 2.1 of the GNU Lesser General Public # License as published by the Free Software Foundation. # # This library is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # Lesser General Public License for more details. # # You should have received a copy of the GNU Lesser General Public # License along with this library; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA # """This module contains the implementation of the ssh-connection service, which allows access to the shell and port-forwarding. This module is unstable. Maintainer: U{Paul Swartz} """ import struct, types from twisted.internet import protocol, reactor, defer from twisted.python import log from twisted.conch import error import service, common, session, forwarding class SSHConnection(service.SSHService): name = 'ssh-connection' def __init__(self): self.localChannelID = 0 # this is the current # to use for channel ID self.localToRemoteChannel = {} # local channel ID -> remote channel ID self.channels = {} # local channel ID -> subclass of SSHChannel self.channelsToRemoteChannel = {} # subclass of SSHChannel -> # remote channel ID self.deferreds = {} # local channel -> list of deferreds for pending # requests or 'global' -> list of deferreds for # global requests self.transport = None # gets set later def serviceStarted(self): if hasattr(self.transport, 'avatar'): self.transport.avatar.conn = self def serviceStopped(self): for channel in self.channels.values(): channel.closed() # packet methods def ssh_GLOBAL_REQUEST(self, packet): requestType, rest = common.getNS(packet) wantReply, rest = ord(rest[0]), rest[1:] reply = MSG_REQUEST_FAILURE data = '' ret = self.gotGlobalRequest(requestType, rest) if ret: reply = MSG_REQUEST_SUCCESS if type(ret) in (types.TupleType, types.ListType): data = ret[1] else: reply = MSG_REQUEST_FAILURE if wantReply: self.transport.sendPacket(reply, data) def ssh_REQUEST_SUCCESS(self, packet): data = packet self.deferreds['global'].pop(0).callback(data) def ssh_REQUEST_FAILURE(self, packet): self.deferreds['global'].pop(0).errback( error.ConchError('global request failed', packet)) def ssh_CHANNEL_OPEN(self, packet): 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 self.transport.sendPacket(MSG_CHANNEL_OPEN_CONFIRMATION, struct.pack('>4L', senderChannel, localChannel, channel.localWindowSize, channel.localMaxPacket)+channel.specificData) channel.channelOpen('') except Exception, e: log.msg('channel open failed') log.err(e) if isinstance(e, error.ConchError): reason, textualInfo = e.data, e.args[0] else: reason = OPEN_CONNECT_FAILED textualInfo = "unknown failure" self.transport.sendPacket(MSG_CHANNEL_OPEN_FAILURE, struct.pack('>2L', senderChannel, reason)+ \ common.NS(textualInfo)+common.NS('')) def ssh_CHANNEL_OPEN_CONFIRMATION(self, packet): 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): 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) reason.desc = reasonDesc reason.code = reasonCode channel.openFailed(reason) def ssh_CHANNEL_WINDOW_ADJUST(self, packet): localChannel, bytesToAdd = struct.unpack('>2L', packet[: 8]) self.channels[localChannel].addWindowBytes(bytesToAdd) def ssh_CHANNEL_DATA(self, packet): 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.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) #log.msg('local window left: %s/%s' % (channel.localWindowLeft, # channel.localWindowSize)) channel.dataReceived(data) def ssh_CHANNEL_EXTENDED_DATA(self, packet): localChannel, typeCode, dataLength = struct.unpack('>3L', packet[: 12]) channel = self.channels[localChannel] if dataLength > channel.localWindowLeft or \ dataLength > channel.localMaxPacket: log.msg('closing channel %s for too much extended data' % channel.id) 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) self.channels[localChannel].extReceived(typeCode, data) def ssh_CHANNEL_EOF(self, packet): localChannel = struct.unpack('>L', packet[: 4])[0] self.channels[localChannel].eofReceived() def ssh_CHANNEL_CLOSE(self, packet): localChannel = struct.unpack('>L', packet[: 4])[0] channel = self.channels[localChannel] channel.remoteClosed = 1 if channel.localClosed and channel.remoteClosed: del self.localToRemoteChannel[localChannel] del self.channels[localChannel] del self.channelsToRemoteChannel[channel] channel.closed() def ssh_CHANNEL_REQUEST(self, packet): localChannel = struct.unpack('>L', packet[: 4])[0] requestType, rest = common.getNS(packet[4:]) wantReply = ord(rest[0]) d = self.channels[localChannel].requestReceived(requestType, rest[1:]) if wantReply: if isinstance(d, defer.Deferred): d.addCallback(self._cbChannelRequest, localChannel) d.addErrback(self._ebChannelRequest, localChannel) elif d: self._cbChannelRequest(None, localChannel) else: self._ebChannelRequest(None, localChannel) def _cbChannelRequest(self, result, localChannel): self.transport.sendPacket(MSG_CHANNEL_SUCCESS, struct.pack('>L', self.localToRemoteChannel[localChannel])) def _ebChannelRequest(self, result, localChannel): self.transport.sendPacket(MSG_CHANNEL_FAILURE, struct.pack('>L', self.localToRemoteChannel[localChannel])) def ssh_CHANNEL_SUCCESS(self, packet): localChannel = struct.unpack('>L', packet[: 4])[0] if self.deferreds.has_key(localChannel): d = self.deferreds[localChannel].pop(0) d.callback(packet[4:]) def ssh_CHANNEL_FAILURE(self, packet): localChannel = struct.unpack('>L', packet[: 4])[0] if self.deferreds.has_key(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: C{str} @type data: C{str} @type wantReply: C{bool} @rtype C{Deferred}/C{None} """ self.transport.sendPacket(MSG_GLOBAL_REQUEST, common.NS(request) + (wantReply and '\xff' or '\x00') + data) if wantReply: d = defer.Deferred() self.deferreds.setdefault('global', []).append(d) return d def openChannel(self, channel, extra = ''): """ Open a new channel on this connection. @type channel: subclass of C{SSHChannel} @type extra: C{str} """ log.msg('opening channel %s with %s %s'%(self.localChannelID, channel.localWindowSize, 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: C{str} @type data: C{str} @type wantReply: C{bool} @rtype C{Deferred}/C{None} """ if not self.channelsToRemoteChannel.has_key(channel): return log.msg('sending request for channel %s, request %s' % (channel.id, requestType), system=self.transport.transport.logPrefix()) self.transport.sendPacket(MSG_CHANNEL_REQUEST, struct.pack('>L', self.channelsToRemoteChannel[channel]) + common.NS(requestType)+chr(wantReply) + 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 C{SSHChannel} @type bytesToAdd: C{int} """ if not self.channelsToRemoteChannel.has_key(channel): return # we're already closed self.transport.sendPacket(MSG_CHANNEL_WINDOW_ADJUST, struct.pack('>2L', self.channelsToRemoteChannel[channel], bytesToAdd)) log.msg('adding %i to %i in channel %i' % (bytesToAdd, channel.localWindowLeft, 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 C{SSHChannel} @type data: C{str} """ if not self.channelsToRemoteChannel.has_key(channel): 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 C{SSHChannel} @type dataType: C{int} @type data: C{str} """ if not self.channelsToRemoteChannel.has_key(channel): 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 C{SSHChannel} """ if not self.channelsToRemoteChannel.has_key(channel): return # we're already closed self.transport.sendPacket(MSG_CHANNEL_EOF, struct.pack('>L', self.channelsToRemoteChannel[channel])) def sendClose(self, channel): """ Close a channel. @type channel: subclass of C{SSHChannel} """ if not self.channelsToRemoteChannel.has_key(channel): return # we're already closed self.transport.sendPacket(MSG_CHANNEL_CLOSE, struct.pack('>L', self.channelsToRemoteChannel[channel])) if channel.localClosed and channel.remoteClosed: del self.localToRemoteChannel[channel.id] del self.channels[channel.id] del self.channelsToRemoteChannel[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 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: C{str} @type windowSize: C{int} @type maxPacket: C{int} @type data: C{str} @rtype: subclass of C{SSHChannel}/C{tuple} """ log.msg('got channel %s request' % channelType) if hasattr(self.transport, "avatar"): # this is a server! chan = self.transport.avatar.lookupChannel(channelType, windowSize, maxPacket, data) chan.conn = self return chan else: channelType = channelType.translate(TRANSLATE_TABLE) f = getattr(self, 'channel_%s' % channelType, None) if not f: return OPEN_UNKNOWN_CHANNEL_TYPE, "don't know that channel" return f(windowSize, maxPacket, data) 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, : 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: C{str} @type data: C{str} @rtype: C{int}/C{tuple} """ log.msg('got global %s request' % requestType) if hasattr(self.transport, 'avatar'): # this is a server! return self.transport.avatar.gotGlobalRequest(requestType, data) requestType = requestType.replace('-','_') f = getattr(self, 'global_%s' % requestType, None) if not f: return 0 return f(data) 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 EXTENDED_DATA_STDERR = 1 messages = {} import connection for v in dir(connection): if v[: 4] == 'MSG_': messages[getattr(connection, v)] = v # doesn't handle doubles import string alphanums = string.letters + string.digits TRANSLATE_TABLE = ''.join([chr(i) in alphanums and chr(i) or '_' for i in range(256)]) SSHConnection.protocolMessages = messages