code.grnet.gr Git - ncclient/blob - src/ssh.py

   1 # Copyright 2009 Shikhar Bhushan
   2 #
   3 # Licensed under the Apache License, Version 2.0 (the "License");
   4 # you may not use this file except in compliance with the License.
   5 # You may obtain a copy of the License at
   6 #
   7 #    http://www.apache.org/licenses/LICENSE-2.0
   8 #
   9 # Unless required by applicable law or agreed to in writing, software
  10 # distributed under the License is distributed on an "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 # See the License for the specific language governing permissions and
  13 # limitations under the License.
  14
  15 import logging
  16 import paramiko
  17
  18 from select import select as select
  19
  20 from session import Session, SessionError
  21
  22 logger = logging.getLogger('ncclient.ssh')
  23
  24 class SSHError(SessionError): pass
  25
  26 class SSHSession(Session):
  27
  28     BUF_SIZE = 4096
  29     MSG_DELIM = ']]>>]]>'
  30     MSG_DELIM_LEN = len(MSG_DELIM)
  31
  32     def __init__(self, capabilities, load_known_hosts=True,
  33                  missing_host_key_policy=paramiko.RejectPolicy):
  34         Session.__init__(self, capabilities)
  35         self._inBuf = ''
  36         self._outBuf = ''
  37         self._client = SSHClient()
  38         if load_known_hosts:
  39             self._client.load_system_host_keys()
  40         self._client.set_missing_host_key_policy(missing_host_key_policy)
  41
  42     def load_host_keys(self, filename):
  43         self._client.load_host_keys(filename)
  44
  45     def set_missing_host_key_policy(self, policy):
  46         self._client.set_missing_host_key_policy(policy)
  47
  48     def connect(self, hostname, port=830, username=None, password=None,
  49                 key_filename=None, timeout=None, allow_agent=True,
  50                 look_for_keys=True):
  51         self._client.connect(hostname, port=port, username=username,
  52                              password=password, key_filename=key_filename,
  53                              timeout=timeout, allow_agent=allow_agent,
  54                              look_for_keys=look_for_keys)
  55         transport = self._client.get_transport()
  56         self._channel = transport.open_session()
  57         self._channel.invoke_subsystem('netconf')
  58         self._greet()
  59         self.start()
  60
  61     def _close(self):
  62         self._channel.shutdown(2)
  63
  64     def run(self):
  65         sock = self._channel
  66         sock.setblocking(0)
  67         q = self._q
  68         while True:
  69             (r, w, e) = select([sock], [sock], [], 60)
  70             if w:
  71                 if not q.empty():
  72                    self._outBuffer += ( q.get() + MSG_DELIM )
  73                 if self._outBuffer:
  74                     n = sock.send(self._outBuffer)
  75                     self._outBuffer = self._outBuffer[n:]
  76             if r:
  77                 data = sock.recv(BUF_SIZE)
  78                 if data:
  79                     self._inBuf += data
  80                     (before, _, after) = self._inBuf.partition(MSG_DELIM)
  81                     if after:
  82                          # we don't want this thread to ground to a halt
  83                          # because of an error dispatching one reply...
  84                         try: self.dispatch('reply', before)
  85                         except: pass
  86                         self._inBuf = after
  87                 else:
  88                     self.dispatch('error', self._inBuf)
  89
  90
  91 class CallbackPolicy(paramiko.MissingHostKeyPolicy):
  92
  93     def __init__(self, cb):
  94         self._cb = cb
  95
  96     def missing_host_key(self, client, hostname, key):
  97         if not self._cb(hostname, key):
  98             raise SSHError