paramiko.server

Package paramiko :: Module server |
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# Source Code for Module paramiko.server

      1  # Copyright (C) 2003-2007  Robey Pointer <robeypointer@gmail.com>
      2  #
      3  # This file is part of paramiko.
      4  #
      5  # Paramiko is free software; you can redistribute it and/or modify it under the
      6  # terms of the GNU Lesser General Public License as published by the Free
      7  # Software Foundation; either version 2.1 of the License, or (at your option)
      8  # any later version.
      9  #
     10  # Paramiko is distributed in the hope that it will be useful, but WITHOUT ANY
     11  # WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
     12  # A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
     13  # details.
     14  #
     15  # You should have received a copy of the GNU Lesser General Public License
     16  # along with Paramiko; if not, write to the Free Software Foundation, Inc.,
     17  # 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
     18
     19  """
     20  L{ServerInterface} is an interface to override for server support.
     21  """
     22
     23  import threading
     24  from paramiko.common import *
     25  from paramiko import util
     26
     27
     28 -class InteractiveQuery (object):
     29      """
     30      A query (set of prompts) for a user during interactive authentication.
     31      """
     32
     33 -    def __init__(self, name='', instructions='', *prompts):
     34          """
     35          Create a new interactive query to send to the client.  The name and
     36          instructions are optional, but are generally displayed to the end
     37          user.  A list of prompts may be included, or they may be added via
     38          the L{add_prompt} method.
     39
     40          @param name: name of this query
     41          @type name: str
     42          @param instructions: user instructions (usually short) about this query
     43          @type instructions: str
     44          @param prompts: one or more authentication prompts
     45          @type prompts: str
     46          """
     47          self.name = name
     48          self.instructions = instructions
     49          self.prompts = []
     50          for x in prompts:
     51              if (type(x) is str) or (type(x) is unicode):
     52                  self.add_prompt(x)
     53              else:
     54                  self.add_prompt(x[0], x[1])
     55
     56 -    def add_prompt(self, prompt, echo=True):
     57          """
     58          Add a prompt to this query.  The prompt should be a (reasonably short)
     59          string.  Multiple prompts can be added to the same query.
     60
     61          @param prompt: the user prompt
     62          @type prompt: str
     63          @param echo: C{True} (default) if the user's response should be echoed;
     64              C{False} if not (for a password or similar)
     65          @type echo: bool
     66          """
     67          self.prompts.append((prompt, echo))
     68
     69
     70 -class ServerInterface (object):
     71      """
     72      This class defines an interface for controlling the behavior of paramiko
     73      in server mode.
     74
     75      Methods on this class are called from paramiko's primary thread, so you
     76      shouldn't do too much work in them.  (Certainly nothing that blocks or
     77      sleeps.)
     78      """
     79
     80 -    def check_channel_request(self, kind, chanid):
     81          """
     82          Determine if a channel request of a given type will be granted, and
     83          return C{OPEN_SUCCEEDED} or an error code.  This method is
     84          called in server mode when the client requests a channel, after
     85          authentication is complete.
     86
     87          If you allow channel requests (and an ssh server that didn't would be
     88          useless), you should also override some of the channel request methods
     89          below, which are used to determine which services will be allowed on
     90          a given channel:
     91              - L{check_channel_pty_request}
     92              - L{check_channel_shell_request}
     93              - L{check_channel_subsystem_request}
     94              - L{check_channel_window_change_request}
     95              - L{check_channel_x11_request}
     96              - L{check_channel_forward_agent_request}
     97
     98          The C{chanid} parameter is a small number that uniquely identifies the
     99          channel within a L{Transport}.  A L{Channel} object is not created
    100          unless this method returns C{OPEN_SUCCEEDED} -- once a
    101          L{Channel} object is created, you can call L{Channel.get_id} to
    102          retrieve the channel ID.
    103
    104          The return value should either be C{OPEN_SUCCEEDED} (or
    105          C{0}) to allow the channel request, or one of the following error
    106          codes to reject it:
    107              - C{OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED}
    108              - C{OPEN_FAILED_CONNECT_FAILED}
    109              - C{OPEN_FAILED_UNKNOWN_CHANNEL_TYPE}
    110              - C{OPEN_FAILED_RESOURCE_SHORTAGE}
    111
    112          The default implementation always returns
    113          C{OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED}.
    114
    115          @param kind: the kind of channel the client would like to open
    116              (usually C{"session"}).
    117          @type kind: str
    118          @param chanid: ID of the channel
    119          @type chanid: int
    120          @return: a success or failure code (listed above)
    121          @rtype: int
    122          """
    123          return OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED
    124
    125 -    def get_allowed_auths(self, username):
    126          """
    127          Return a list of authentication methods supported by the server.
    128          This list is sent to clients attempting to authenticate, to inform them
    129          of authentication methods that might be successful.
    130
    131          The "list" is actually a string of comma-separated names of types of
    132          authentication.  Possible values are C{"password"}, C{"publickey"},
    133          and C{"none"}.
    134
    135          The default implementation always returns C{"password"}.
    136
    137          @param username: the username requesting authentication.
    138          @type username: str
    139          @return: a comma-separated list of authentication types
    140          @rtype: str
    141          """
    142          return 'password'
    143
    144 -    def check_auth_none(self, username):
    145          """
    146          Determine if a client may open channels with no (further)
    147          authentication.
    148
    149          Return L{AUTH_FAILED} if the client must authenticate, or
    150          L{AUTH_SUCCESSFUL} if it's okay for the client to not
    151          authenticate.
    152
    153          The default implementation always returns L{AUTH_FAILED}.
    154
    155          @param username: the username of the client.
    156          @type username: str
    157          @return: L{AUTH_FAILED} if the authentication fails;
    158              L{AUTH_SUCCESSFUL} if it succeeds.
    159          @rtype: int
    160          """
    161          return AUTH_FAILED
    162
    163 -    def check_auth_password(self, username, password):
    164          """
    165          Determine if a given username and password supplied by the client is
    166          acceptable for use in authentication.
    167
    168          Return L{AUTH_FAILED} if the password is not accepted,
    169          L{AUTH_SUCCESSFUL} if the password is accepted and completes
    170          the authentication, or L{AUTH_PARTIALLY_SUCCESSFUL} if your
    171          authentication is stateful, and this key is accepted for
    172          authentication, but more authentication is required.  (In this latter
    173          case, L{get_allowed_auths} will be called to report to the client what
    174          options it has for continuing the authentication.)
    175
    176          The default implementation always returns L{AUTH_FAILED}.
    177
    178          @param username: the username of the authenticating client.
    179          @type username: str
    180          @param password: the password given by the client.
    181          @type password: str
    182          @return: L{AUTH_FAILED} if the authentication fails;
    183              L{AUTH_SUCCESSFUL} if it succeeds;
    184              L{AUTH_PARTIALLY_SUCCESSFUL} if the password auth is
    185              successful, but authentication must continue.
    186          @rtype: int
    187          """
    188          return AUTH_FAILED
    189
    190 -    def check_auth_publickey(self, username, key):
    191          """
    192          Determine if a given key supplied by the client is acceptable for use
    193          in authentication.  You should override this method in server mode to
    194          check the username and key and decide if you would accept a signature
    195          made using this key.
    196
    197          Return L{AUTH_FAILED} if the key is not accepted,
    198          L{AUTH_SUCCESSFUL} if the key is accepted and completes the
    199          authentication, or L{AUTH_PARTIALLY_SUCCESSFUL} if your
    200          authentication is stateful, and this password is accepted for
    201          authentication, but more authentication is required.  (In this latter
    202          case, L{get_allowed_auths} will be called to report to the client what
    203          options it has for continuing the authentication.)
    204
    205          Note that you don't have to actually verify any key signtature here.
    206          If you're willing to accept the key, paramiko will do the work of
    207          verifying the client's signature.
    208
    209          The default implementation always returns L{AUTH_FAILED}.
    210
    211          @param username: the username of the authenticating client
    212          @type username: str
    213          @param key: the key object provided by the client
    214          @type key: L{PKey <pkey.PKey>}
    215          @return: L{AUTH_FAILED} if the client can't authenticate
    216              with this key; L{AUTH_SUCCESSFUL} if it can;
    217              L{AUTH_PARTIALLY_SUCCESSFUL} if it can authenticate with
    218              this key but must continue with authentication
    219          @rtype: int
    220          """
    221          return AUTH_FAILED
    222
    223 -    def check_auth_interactive(self, username, submethods):
    224          """
    225          Begin an interactive authentication challenge, if supported.  You
    226          should override this method in server mode if you want to support the
    227          C{"keyboard-interactive"} auth type, which requires you to send a
    228          series of questions for the client to answer.
    229
    230          Return L{AUTH_FAILED} if this auth method isn't supported.  Otherwise,
    231          you should return an L{InteractiveQuery} object containing the prompts
    232          and instructions for the user.  The response will be sent via a call
    233          to L{check_auth_interactive_response}.
    234
    235          The default implementation always returns L{AUTH_FAILED}.
    236
    237          @param username: the username of the authenticating client
    238          @type username: str
    239          @param submethods: a comma-separated list of methods preferred by the
    240              client (usually empty)
    241          @type submethods: str
    242          @return: L{AUTH_FAILED} if this auth method isn't supported; otherwise
    243              an object containing queries for the user
    244          @rtype: int or L{InteractiveQuery}
    245          """
    246          return AUTH_FAILED
    247
    248 -    def check_auth_interactive_response(self, responses):
    249          """
    250          Continue or finish an interactive authentication challenge, if
    251          supported.  You should override this method in server mode if you want
    252          to support the C{"keyboard-interactive"} auth type.
    253
    254          Return L{AUTH_FAILED} if the responses are not accepted,
    255          L{AUTH_SUCCESSFUL} if the responses are accepted and complete
    256          the authentication, or L{AUTH_PARTIALLY_SUCCESSFUL} if your
    257          authentication is stateful, and this set of responses is accepted for
    258          authentication, but more authentication is required.  (In this latter
    259          case, L{get_allowed_auths} will be called to report to the client what
    260          options it has for continuing the authentication.)
    261
    262          If you wish to continue interactive authentication with more questions,
    263          you may return an L{InteractiveQuery} object, which should cause the
    264          client to respond with more answers, calling this method again.  This
    265          cycle can continue indefinitely.
    266
    267          The default implementation always returns L{AUTH_FAILED}.
    268
    269          @param responses: list of responses from the client
    270          @type responses: list(str)
    271          @return: L{AUTH_FAILED} if the authentication fails;
    272              L{AUTH_SUCCESSFUL} if it succeeds;
    273              L{AUTH_PARTIALLY_SUCCESSFUL} if the interactive auth is
    274              successful, but authentication must continue; otherwise an object
    275              containing queries for the user
    276          @rtype: int or L{InteractiveQuery}
    277          """
    278          return AUTH_FAILED
    279
    280 -    def check_port_forward_request(self, address, port):
    281          """
    282          Handle a request for port forwarding.  The client is asking that
    283          connections to the given address and port be forwarded back across
    284          this ssh connection.  An address of C{"0.0.0.0"} indicates a global
    285          address (any address associated with this server) and a port of C{0}
    286          indicates that no specific port is requested (usually the OS will pick
    287          a port).
    288
    289          The default implementation always returns C{False}, rejecting the
    290          port forwarding request.  If the request is accepted, you should return
    291          the port opened for listening.
    292
    293          @param address: the requested address
    294          @type address: str
    295          @param port: the requested port
    296          @type port: int
    297          @return: the port number that was opened for listening, or C{False} to
    298              reject
    299          @rtype: int
    300          """
    301          return False
    302
    303 -    def cancel_port_forward_request(self, address, port):
    304          """
    305          The client would like to cancel a previous port-forwarding request.
    306          If the given address and port is being forwarded across this ssh
    307          connection, the port should be closed.
    308
    309          @param address: the forwarded address
    310          @type address: str
    311          @param port: the forwarded port
    312          @type port: int
    313          """
    314          pass
    315
    316 -    def check_global_request(self, kind, msg):
    317          """
    318          Handle a global request of the given C{kind}.  This method is called
    319          in server mode and client mode, whenever the remote host makes a global
    320          request.  If there are any arguments to the request, they will be in
    321          C{msg}.
    322
    323          There aren't any useful global requests defined, aside from port
    324          forwarding, so usually this type of request is an extension to the
    325          protocol.
    326
    327          If the request was successful and you would like to return contextual
    328          data to the remote host, return a tuple.  Items in the tuple will be
    329          sent back with the successful result.  (Note that the items in the
    330          tuple can only be strings, ints, longs, or bools.)
    331
    332          The default implementation always returns C{False}, indicating that it
    333          does not support any global requests.
    334
    335          @note: Port forwarding requests are handled separately, in
    336              L{check_port_forward_request}.
    337
    338          @param kind: the kind of global request being made.
    339          @type kind: str
    340          @param msg: any extra arguments to the request.
    341          @type msg: L{Message}
    342          @return: C{True} or a tuple of data if the request was granted;
    343              C{False} otherwise.
    344          @rtype: bool
    345          """
    346          return False
    347
    348
    349      ###  Channel requests
    350
    351
    352 -    def check_channel_pty_request(self, channel, term, width, height, pixelwidth, pixelheight,
    353                                    modes):
    354          """
    355          Determine if a pseudo-terminal of the given dimensions (usually
    356          requested for shell access) can be provided on the given channel.
    357
    358          The default implementation always returns C{False}.
    359
    360          @param channel: the L{Channel} the pty request arrived on.
    361          @type channel: L{Channel}
    362          @param term: type of terminal requested (for example, C{"vt100"}).
    363          @type term: str
    364          @param width: width of screen in characters.
    365          @type width: int
    366          @param height: height of screen in characters.
    367          @type height: int
    368          @param pixelwidth: width of screen in pixels, if known (may be C{0} if
    369              unknown).
    370          @type pixelwidth: int
    371          @param pixelheight: height of screen in pixels, if known (may be C{0}
    372              if unknown).
    373          @type pixelheight: int
    374          @return: C{True} if the psuedo-terminal has been allocated; C{False}
    375              otherwise.
    376          @rtype: bool
    377          """
    378          return False
    379
    380 -    def check_channel_shell_request(self, channel):
    381          """
    382          Determine if a shell will be provided to the client on the given
    383          channel.  If this method returns C{True}, the channel should be
    384          connected to the stdin/stdout of a shell (or something that acts like
    385          a shell).
    386
    387          The default implementation always returns C{False}.
    388
    389          @param channel: the L{Channel} the request arrived on.
    390          @type channel: L{Channel}
    391          @return: C{True} if this channel is now hooked up to a shell; C{False}
    392              if a shell can't or won't be provided.
    393          @rtype: bool
    394          """
    395          return False
    396
    397 -    def check_channel_exec_request(self, channel, command):
    398          """
    399          Determine if a shell command will be executed for the client.  If this
    400          method returns C{True}, the channel should be connected to the stdin,
    401          stdout, and stderr of the shell command.
    402
    403          The default implementation always returns C{False}.
    404
    405          @param channel: the L{Channel} the request arrived on.
    406          @type channel: L{Channel}
    407          @param command: the command to execute.
    408          @type command: str
    409          @return: C{True} if this channel is now hooked up to the stdin,
    410              stdout, and stderr of the executing command; C{False} if the
    411              command will not be executed.
    412          @rtype: bool
    413
    414          @since: 1.1
    415          """
    416          return False
    417
    418 -    def check_channel_subsystem_request(self, channel, name):
    419          """
    420          Determine if a requested subsystem will be provided to the client on
    421          the given channel.  If this method returns C{True}, all future I/O
    422          through this channel will be assumed to be connected to the requested
    423          subsystem.  An example of a subsystem is C{sftp}.
    424
    425          The default implementation checks for a subsystem handler assigned via
    426          L{Transport.set_subsystem_handler}.
    427          If one has been set, the handler is invoked and this method returns
    428          C{True}.  Otherwise it returns C{False}.
    429
    430          @note: Because the default implementation uses the L{Transport} to
    431              identify valid subsystems, you probably won't need to override this
    432              method.
    433
    434          @param channel: the L{Channel} the pty request arrived on.
    435          @type channel: L{Channel}
    436          @param name: name of the requested subsystem.
    437          @type name: str
    438          @return: C{True} if this channel is now hooked up to the requested
    439              subsystem; C{False} if that subsystem can't or won't be provided.
    440          @rtype: bool
    441          """
    442          handler_class, larg, kwarg = channel.get_transport()._get_subsystem_handler(name)
    443          if handler_class is None:
    444              return False
    445          handler = handler_class(channel, name, self, *larg, **kwarg)
    446          handler.start()
    447          return True
    448
    449 -    def check_channel_window_change_request(self, channel, width, height, pixelwidth, pixelheight):
    450          """
    451          Determine if the pseudo-terminal on the given channel can be resized.
    452          This only makes sense if a pty was previously allocated on it.
    453
    454          The default implementation always returns C{False}.
    455
    456          @param channel: the L{Channel} the pty request arrived on.
    457          @type channel: L{Channel}
    458          @param width: width of screen in characters.
    459          @type width: int
    460          @param height: height of screen in characters.
    461          @type height: int
    462          @param pixelwidth: width of screen in pixels, if known (may be C{0} if
    463              unknown).
    464          @type pixelwidth: int
    465          @param pixelheight: height of screen in pixels, if known (may be C{0}
    466              if unknown).
    467          @type pixelheight: int
    468          @return: C{True} if the terminal was resized; C{False} if not.
    469          @rtype: bool
    470          """
    471          return False
    472
    473 -    def check_channel_x11_request(self, channel, single_connection, auth_protocol, auth_cookie, screen_number):
    474          """
    475          Determine if the client will be provided with an X11 session.  If this
    476          method returns C{True}, X11 applications should be routed through new
    477          SSH channels, using L{Transport.open_x11_channel}.
    478
    479          The default implementation always returns C{False}.
    480
    481          @param channel: the L{Channel} the X11 request arrived on
    482          @type channel: L{Channel}
    483          @param single_connection: C{True} if only a single X11 channel should
    484              be opened
    485          @type single_connection: bool
    486          @param auth_protocol: the protocol used for X11 authentication
    487          @type auth_protocol: str
    488          @param auth_cookie: the cookie used to authenticate to X11
    489          @type auth_cookie: str
    490          @param screen_number: the number of the X11 screen to connect to
    491          @type screen_number: int
    492          @return: C{True} if the X11 session was opened; C{False} if not
    493          @rtype: bool
    494          """
    495          return False
    496
    497 -    def check_channel_forward_agent_request(self, channel):
    498          """
    499          Determine if the client will be provided with an forward agent session.
    500          If this method returns C{True}, the server will allow SSH Agent
    501          forwarding.
    502
    503          The default implementation always returns C{False}.
    504
    505          @param channel: the L{Channel} the request arrived on
    506          @type channel: L{Channel}
    507          @return: C{True} if the AgentForward was loaded; C{False} if not
    508          @rtype: bool
    509          """
    510          return False
    511
    512 -    def check_channel_direct_tcpip_request(self, chanid, origin, destination):
    513          """
    514          Determine if a local port forwarding channel will be granted, and
    515          return C{OPEN_SUCCEEDED} or an error code.  This method is
    516          called in server mode when the client requests a channel, after
    517          authentication is complete.
    518
    519          The C{chanid} parameter is a small number that uniquely identifies the
    520          channel within a L{Transport}.  A L{Channel} object is not created
    521          unless this method returns C{OPEN_SUCCEEDED} -- once a
    522          L{Channel} object is created, you can call L{Channel.get_id} to
    523          retrieve the channel ID.
    524
    525          The origin and destination parameters are (ip_address, port) tuples
    526          that correspond to both ends of the TCP connection in the forwarding
    527          tunnel.
    528
    529          The return value should either be C{OPEN_SUCCEEDED} (or
    530          C{0}) to allow the channel request, or one of the following error
    531          codes to reject it:
    532              - C{OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED}
    533              - C{OPEN_FAILED_CONNECT_FAILED}
    534              - C{OPEN_FAILED_UNKNOWN_CHANNEL_TYPE}
    535              - C{OPEN_FAILED_RESOURCE_SHORTAGE}
    536
    537          The default implementation always returns
    538          C{OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED}.
    539
    540          @param chanid: ID of the channel
    541          @type chanid: int
    542          @param origin: 2-tuple containing the IP address and port of the
    543              originator (client side)
    544          @type origin: tuple
    545          @param destination: 2-tuple containing the IP address and port of the
    546              destination (server side)
    547          @type destination: tuple
    548          @return: a success or failure code (listed above)
    549          @rtype: int
    550          """
    551          return OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED
    552
    553 -    def check_channel_env_request(self, channel, name, value):
    554          """
    555          Check whether a given environment variable can be specified for the
    556          given channel.  This method should return C{True} if the server
    557          is willing to set the specified environment variable.  Note that
    558          some environment variables (e.g., PATH) can be exceedingly
    559          dangerous, so blindly allowing the client to set the environment
    560          is almost certainly not a good idea.
    561
    562          The default implementation always returns C{False}.
    563
    564          @param channel: the L{Channel} the env request arrived on
    565          @type channel: L{Channel}
    566          @param name: foo bar baz
    567          @type name: str
    568          @param value: flklj
    569          @type value: str
    570          @rtype: bool
    571          """
    572          return False
    573
    574
    575 -class SubsystemHandler (threading.Thread):
    576      """
    577      Handler for a subsytem in server mode.  If you create a subclass of this
    578      class and pass it to
    579      L{Transport.set_subsystem_handler},
    580      an object of this
    581      class will be created for each request for this subsystem.  Each new object
    582      will be executed within its own new thread by calling L{start_subsystem}.
    583      When that method completes, the channel is closed.
    584
    585      For example, if you made a subclass C{MP3Handler} and registered it as the
    586      handler for subsystem C{"mp3"}, then whenever a client has successfully
    587      authenticated and requests subsytem C{"mp3"}, an object of class
    588      C{MP3Handler} will be created, and L{start_subsystem} will be called on
    589      it from a new thread.
    590      """
    591 -    def __init__(self, channel, name, server):
    592          """
    593          Create a new handler for a channel.  This is used by L{ServerInterface}
    594          to start up a new handler when a channel requests this subsystem.  You
    595          don't need to override this method, but if you do, be sure to pass the
    596          C{channel} and C{name} parameters through to the original C{__init__}
    597          method here.
    598
    599          @param channel: the channel associated with this subsystem request.
    600          @type channel: L{Channel}
    601          @param name: name of the requested subsystem.
    602          @type name: str
    603          @param server: the server object for the session that started this
    604              subsystem
    605          @type server: L{ServerInterface}
    606          """
    607          threading.Thread.__init__(self, target=self._run)
    608          self.__channel = channel
    609          self.__transport = channel.get_transport()
    610          self.__name = name
    611          self.__server = server
    612
    613 -    def get_server(self):
    614          """
    615          Return the L{ServerInterface} object associated with this channel and
    616          subsystem.
    617
    618          @rtype: L{ServerInterface}
    619          """
    620          return self.__server
    621
    622 -    def _run(self):
    623          try:
    624              self.__transport._log(DEBUG, 'Starting handler for subsystem %s' % self.__name)
    625              self.start_subsystem(self.__name, self.__transport, self.__channel)
    626          except Exception, e:
    627              self.__transport._log(ERROR, 'Exception in subsystem handler for "%s": %s' %
    628                                    (self.__name, str(e)))
    629              self.__transport._log(ERROR, util.tb_strings())
    630          try:
    631              self.finish_subsystem()
    632          except:
    633              pass
    634
    635 -    def start_subsystem(self, name, transport, channel):
    636          """
    637          Process an ssh subsystem in server mode.  This method is called on a
    638          new object (and in a new thread) for each subsystem request.  It is
    639          assumed that all subsystem logic will take place here, and when the
    640          subsystem is finished, this method will return.  After this method
    641          returns, the channel is closed.
    642
    643          The combination of C{transport} and C{channel} are unique; this handler
    644          corresponds to exactly one L{Channel} on one L{Transport}.
    645
    646          @note: It is the responsibility of this method to exit if the
    647              underlying L{Transport} is closed.  This can be done by checking
    648              L{Transport.is_active} or noticing an EOF
    649              on the L{Channel}.  If this method loops forever without checking
    650              for this case, your python interpreter may refuse to exit because
    651              this thread will still be running.
    652
    653          @param name: name of the requested subsystem.
    654          @type name: str
    655          @param transport: the server-mode L{Transport}.
    656          @type transport: L{Transport}
    657          @param channel: the channel associated with this subsystem request.
    658          @type channel: L{Channel}
    659          """
    660          pass
    661
    662 -    def finish_subsystem(self):
    663          """
    664          Perform any cleanup at the end of a subsystem.  The default
    665          implementation just closes the channel.
    666
    667          @since: 1.1
    668          """
    669          self.__channel.close()
    670