pyassuan/server.py

   1 # Copyright (C) 2012 W. Trevor King <wking@drexel.edu>
   2 #
   3 # This file is part of pyassuan.
   4 #
   5 # pyassuan is free software: you can redistribute it and/or modify it under the
   6 # terms of the GNU General Public License as published by the Free Software
   7 # Foundation, either version 3 of the License, or (at your option) any later
   8 # version.
   9 #
  10 # pyassuan 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 General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU General Public License along with
  15 # pyassuan.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 import logging as _logging
  18 import re as _re
  19 import socket as _socket
  20 import sys as _sys
  21 import threading as _threading
  22 import traceback as _traceback
  23
  24 from . import LOG as _LOG
  25 from . import common as _common
  26 from . import error as _error
  27
  28
  29 _OPTION_REGEXP = _re.compile('^-?-?([-\w]+)( *)(=?) *(.*?) *\Z')
  30
  31
  32 class AssuanServer (object):
  33     """A single-threaded Assuan server based on the `devolpment suggestions`_
  34
  35     Extend by subclassing and adding ``_handle_XXX`` methods for each
  36     command you want to handle.
  37
  38     .. _development suggestions:
  39       http://www.gnupg.org/documentation/manuals/assuan/Server-code.html
  40     """
  41     def __init__(self, name, logger=_LOG, use_sublogger=True,
  42                  valid_options=None, strict_options=True,
  43                  single_request=False, listen_to_quit=False,
  44                  close_on_disconnect=False):
  45         self.name = name
  46         if use_sublogger:
  47             logger = _logging.getLogger('{}.{}'.format(logger.name, self.name))
  48         self.logger = logger
  49         if valid_options is None:
  50             valid_options = []
  51         self.valid_options = valid_options
  52         self.strict_options = strict_options
  53         self.single_request = single_request
  54         self.listen_to_quit = listen_to_quit
  55         self.close_on_disconnect = close_on_disconnect
  56         self.input = self.output = None
  57         self.options = {}
  58         self.reset()
  59
  60     def reset(self):
  61         self.stop = False
  62         self.options.clear()
  63
  64     def run(self):
  65         self.reset()
  66         self.logger.info('running')
  67         self.connect()
  68         try:
  69             self.handle_requests()
  70         finally:
  71             self.disconnect()
  72             self.logger.info('stopping')
  73
  74     def connect(self):
  75         if not self.input:
  76             self.logger.info('read from stdin')
  77             self.input = _sys.stdin
  78         if not self.output:
  79             self.logger.info('write to stdout')
  80             self.output = _sys.stdout
  81
  82     def disconnect(self):
  83         if self.close_on_disconnect:
  84             self.logger.info('disconnecting')
  85             self.input = None
  86             self.output = None
  87
  88     def handle_requests(self):
  89         self.send_response(_common.Response('OK', 'Your orders please'))
  90         self.output.flush()
  91         while not self.stop:
  92             line = self.input.readline()
  93             if not line:
  94                 break  # EOF
  95             if not line.endswith('\n'):
  96                 self.logger.info('C: {}'.format(line))
  97                 self.send_error_response(
  98                     _error.AssuanError(message='Invalid request'))
  99                 continue
 100             line = line[:-1]  # remove the trailing newline
 101             self.logger.info('C: {}'.format(line))
 102             request = _common.Request()
 103             try:
 104                 request.from_string(line)
 105             except _error.AssuanError as e:
 106                 self.send_error_response(e)
 107                 continue
 108             self.handle_request(request)
 109
 110     def handle_request(self, request):
 111         try:
 112             handle = getattr(
 113                 self, '_handle_{}'.format(request.command))
 114         except AttributeError:
 115             self.send_error_response(
 116                 _error.AssuanError(message='Unknown command'))
 117             return
 118         try:
 119             responses = handle(request.parameters)
 120             for response in responses:
 121                 self.send_response(response)
 122         except _error.AssuanError as error:
 123             self.send_error_response(error)
 124             return
 125         except Exception as e:
 126             self.logger.error(
 127                 'exception while executing {}:\n{}'.format(
 128                     handle, _traceback.format_exc().rstrip()))
 129             self.send_error_response(
 130                 _error.AssuanError(message='Unspecific Assuan server fault'))
 131             return
 132
 133     def send_response(self, response):
 134         """For internal use by ``.handle_requests()``
 135         """
 136         rstring = str(response)
 137         self.logger.info('S: {}'.format(rstring))
 138         self.output.write(rstring)
 139         self.output.write('\n')
 140         try:
 141             self.output.flush()
 142         except IOError:
 143             if not self.stop:
 144                 raise
 145
 146     def send_error_response(self, error):
 147         """For internal use by ``.handle_requests()``
 148         """
 149         self.send_response(_common.error_response(error))
 150
 151     # common commands defined at
 152     # http://www.gnupg.org/documentation/manuals/assuan/Client-requests.html
 153
 154     def _handle_BYE(self, arg):
 155         if self.single_request:
 156             self.stop = True
 157         yield _common.Response('OK', 'closing connection')
 158
 159     def _handle_RESET(self, arg):
 160         self.reset()
 161
 162     def _handle_END(self, arg):
 163         raise _error.AssuanError(
 164             code=175, message='Unknown command (reserved)')
 165
 166     def _handle_HELP(self, arg):
 167         raise _error.AssuanError(
 168             code=175, message='Unknown command (reserved)')
 169
 170     def _handle_QUIT(self, arg):
 171         if self.listen_to_quit:
 172             self.stop = True
 173             yield _common.Response('OK', 'stopping the server')
 174         raise _error.AssuanError(
 175             code=175, message='Unknown command (reserved)')
 176
 177     def _handle_OPTION(self, arg):
 178         """
 179
 180         >>> s = AssuanServer(name='test', valid_options=['my-op'])
 181         >>> list(s._handle_OPTION('my-op = 1 '))  # doctest: +ELLIPSIS
 182         [<pyassuan.common.Response object at ...>]
 183         >>> s.options
 184         {'my-op': '1'}
 185         >>> list(s._handle_OPTION('my-op 2'))  # doctest: +ELLIPSIS
 186         [<pyassuan.common.Response object at ...>]
 187         >>> s.options
 188         {'my-op': '2'}
 189         >>> list(s._handle_OPTION('--my-op 3'))  # doctest: +ELLIPSIS
 190         [<pyassuan.common.Response object at ...>]
 191         >>> s.options
 192         {'my-op': '3'}
 193         >>> list(s._handle_OPTION('my-op'))  # doctest: +ELLIPSIS
 194         [<pyassuan.common.Response object at ...>]
 195         >>> s.options
 196         {'my-op': None}
 197         >>> list(s._handle_OPTION('inv'))
 198         Traceback (most recent call last):
 199           ...
 200         pyassuan.error.AssuanError: 174 Unknown option
 201         >>> list(s._handle_OPTION('in|valid'))
 202         Traceback (most recent call last):
 203           ...
 204         pyassuan.error.AssuanError: 90 Invalid parameter
 205         """
 206         match = _OPTION_REGEXP.match(arg)
 207         if not match:
 208             raise _error.AssuanError(message='Invalid parameter')
 209         name,space,equal,value = match.groups()
 210         if value and not space and not equal:
 211             # need either space or equal to separate value
 212             raise _error.AssuanError(message='Invalid parameter')
 213         if name not in self.valid_options:
 214             if self.strict_options:
 215                 raise _error.AssuanError(message='Unknown option')
 216             else:
 217                 self.logger.info('skipping invalid option: {}'.format(name))
 218         else:
 219             if not value:
 220                 value = None
 221             self.options[name] = value
 222         yield _common.Response('OK')
 223
 224     def _handle_CANCEL(self, arg):
 225         raise _error.AssuanError(
 226             code=175, message='Unknown command (reserved)')
 227
 228     def _handle_AUTH(self, arg):
 229         raise _error.AssuanError(
 230             code=175, message='Unknown command (reserved)')
 231
 232
 233 class AssuanSocketServer (object):
 234     """A threaded server spawning ``AssuanServer``\s for each connection
 235     """
 236     def __init__(self, name, socket, server, kwargs={}, max_threads=10,
 237                  logger=_LOG, use_sublogger=True):
 238         self.name = name
 239         if use_sublogger:
 240             logger = _logging.getLogger('{}.{}'.format(logger.name, self.name))
 241         self.logger = logger
 242         self.socket = socket
 243         self.server = server
 244         assert 'name' not in kwargs, kwargs['name']
 245         assert 'logger' not in kwargs, kwargs['logger']
 246         kwargs['logger'] = self.logger
 247         assert 'use_sublogger' not in kwargs, kwargs['use_sublogger']
 248         kwargs['use_sublogger'] = True
 249         if 'close_on_disconnect' in kwargs:
 250             assert kwargs['close_on_disconnect'] == True, (
 251                 kwargs['close_on_disconnect'])
 252         else:
 253             kwargs['close_on_disconnect'] = True
 254         self.kwargs = kwargs
 255         self.max_threads = max_threads
 256         self.threads = []
 257
 258     def run(self):
 259         self.logger.info('listen on socket')
 260         self.socket.listen()
 261         thread_index = 0
 262         while True:
 263             socket,address = self.socket.accept()
 264             self.logger.info('connection from {}'.format(address))
 265             self.cleanup_threads()
 266             if len(threads) > self.max_threads:
 267                 self.drop_connection(socket, address)
 268             self.spawn_thread(
 269                 'server-thread-{}'.format(thread_index), socket, address)
 270             thread_index = (thread_index + 1) % self.max_threads
 271
 272     def cleanup_threads(self):
 273         i = 0
 274         while i < len(self.threads):
 275             thread = self.threads[i]
 276             thread.join(0)
 277             if thread.is_alive():
 278                 self.logger.info('joined thread {}'.format(thread.name))
 279                 self.threads.pop(i)
 280                 thread.socket.shutdown()
 281                 thread.socket.close()
 282             else:
 283                 i += 1
 284
 285     def drop_connection(self, socket, address):
 286         self.logger.info('drop connection from {}'.format(address))
 287         # TODO: proper error to send to the client?
 288
 289     def spawn_thread(self, name, socket, address):
 290         server = self.server(name=name, **self.kwargs)
 291         server.input = socket.makefile('r')
 292         server.output = socket.makefile('w')
 293         thread = _threading.Thread(target=server.run, name=name)
 294         thread.start()
 295         self.threads.append(thread)