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.buffer
  78         if not self.output:
  79             self.logger.info('write to stdout')
  80             self.output = _sys.stdout.buffer
  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 len(line) > _common.LINE_LENGTH:
  96                 self.raise_error(
  97                     _error.AssuanError(message='Line too long'))
  98             if not line.endswith(b'\n'):
  99                 self.logger.info('C: {}'.format(line))
 100                 self.send_error_response(
 101                     _error.AssuanError(message='Invalid request'))
 102                 continue
 103             line = line[:-1]  # remove the trailing newline
 104             self.logger.info('C: {}'.format(line))
 105             request = _common.Request()
 106             try:
 107                 request.from_bytes(line)
 108             except _error.AssuanError as e:
 109                 self.send_error_response(e)
 110                 continue
 111             self.handle_request(request)
 112
 113     def handle_request(self, request):
 114         try:
 115             handle = getattr(
 116                 self, '_handle_{}'.format(request.command))
 117         except AttributeError:
 118             self.send_error_response(
 119                 _error.AssuanError(message='Unknown command'))
 120             return
 121         try:
 122             responses = handle(request.parameters)
 123             for response in responses:
 124                 self.send_response(response)
 125         except _error.AssuanError as error:
 126             self.send_error_response(error)
 127             return
 128         except Exception as e:
 129             self.logger.error(
 130                 'exception while executing {}:\n{}'.format(
 131                     handle, _traceback.format_exc().rstrip()))
 132             self.send_error_response(
 133                 _error.AssuanError(message='Unspecific Assuan server fault'))
 134             return
 135
 136     def send_response(self, response):
 137         """For internal use by ``.handle_requests()``
 138         """
 139         rstring = str(response)
 140         self.logger.info('S: {}'.format(response))
 141         self.output.write(bytes(response))
 142         self.output.write(b'\n')
 143         try:
 144             self.output.flush()
 145         except IOError:
 146             if not self.stop:
 147                 raise
 148
 149     def send_error_response(self, error):
 150         """For internal use by ``.handle_requests()``
 151         """
 152         self.send_response(_common.error_response(error))
 153
 154     # common commands defined at
 155     # http://www.gnupg.org/documentation/manuals/assuan/Client-requests.html
 156
 157     def _handle_BYE(self, arg):
 158         if self.single_request:
 159             self.stop = True
 160         yield _common.Response('OK', 'closing connection')
 161
 162     def _handle_RESET(self, arg):
 163         self.reset()
 164
 165     def _handle_END(self, arg):
 166         raise _error.AssuanError(
 167             code=175, message='Unknown command (reserved)')
 168
 169     def _handle_HELP(self, arg):
 170         raise _error.AssuanError(
 171             code=175, message='Unknown command (reserved)')
 172
 173     def _handle_QUIT(self, arg):
 174         if self.listen_to_quit:
 175             self.stop = True
 176             yield _common.Response('OK', 'stopping the server')
 177         raise _error.AssuanError(
 178             code=175, message='Unknown command (reserved)')
 179
 180     def _handle_OPTION(self, arg):
 181         """
 182
 183         >>> s = AssuanServer(name='test', valid_options=['my-op'])
 184         >>> list(s._handle_OPTION('my-op = 1 '))  # doctest: +ELLIPSIS
 185         [<pyassuan.common.Response object at ...>]
 186         >>> s.options
 187         {'my-op': '1'}
 188         >>> list(s._handle_OPTION('my-op 2'))  # doctest: +ELLIPSIS
 189         [<pyassuan.common.Response object at ...>]
 190         >>> s.options
 191         {'my-op': '2'}
 192         >>> list(s._handle_OPTION('--my-op 3'))  # doctest: +ELLIPSIS
 193         [<pyassuan.common.Response object at ...>]
 194         >>> s.options
 195         {'my-op': '3'}
 196         >>> list(s._handle_OPTION('my-op'))  # doctest: +ELLIPSIS
 197         [<pyassuan.common.Response object at ...>]
 198         >>> s.options
 199         {'my-op': None}
 200         >>> list(s._handle_OPTION('inv'))
 201         Traceback (most recent call last):
 202           ...
 203         pyassuan.error.AssuanError: 174 Unknown option
 204         >>> list(s._handle_OPTION('in|valid'))
 205         Traceback (most recent call last):
 206           ...
 207         pyassuan.error.AssuanError: 90 Invalid parameter
 208         """
 209         match = _OPTION_REGEXP.match(arg)
 210         if not match:
 211             raise _error.AssuanError(message='Invalid parameter')
 212         name,space,equal,value = match.groups()
 213         if value and not space and not equal:
 214             # need either space or equal to separate value
 215             raise _error.AssuanError(message='Invalid parameter')
 216         if name not in self.valid_options:
 217             if self.strict_options:
 218                 raise _error.AssuanError(message='Unknown option')
 219             else:
 220                 self.logger.info('skipping invalid option: {}'.format(name))
 221         else:
 222             if not value:
 223                 value = None
 224             self.options[name] = value
 225         yield _common.Response('OK')
 226
 227     def _handle_CANCEL(self, arg):
 228         raise _error.AssuanError(
 229             code=175, message='Unknown command (reserved)')
 230
 231     def _handle_AUTH(self, arg):
 232         raise _error.AssuanError(
 233             code=175, message='Unknown command (reserved)')
 234
 235
 236 class AssuanSocketServer (object):
 237     """A threaded server spawning ``AssuanServer``\s for each connection
 238     """
 239     def __init__(self, name, socket, server, kwargs={}, max_threads=10,
 240                  logger=_LOG, use_sublogger=True):
 241         self.name = name
 242         if use_sublogger:
 243             logger = _logging.getLogger('{}.{}'.format(logger.name, self.name))
 244         self.logger = logger
 245         self.socket = socket
 246         self.server = server
 247         assert 'name' not in kwargs, kwargs['name']
 248         assert 'logger' not in kwargs, kwargs['logger']
 249         kwargs['logger'] = self.logger
 250         assert 'use_sublogger' not in kwargs, kwargs['use_sublogger']
 251         kwargs['use_sublogger'] = True
 252         if 'close_on_disconnect' in kwargs:
 253             assert kwargs['close_on_disconnect'] == True, (
 254                 kwargs['close_on_disconnect'])
 255         else:
 256             kwargs['close_on_disconnect'] = True
 257         self.kwargs = kwargs
 258         self.max_threads = max_threads
 259         self.threads = []
 260
 261     def run(self):
 262         self.logger.info('listen on socket')
 263         self.socket.listen()
 264         thread_index = 0
 265         while True:
 266             socket,address = self.socket.accept()
 267             self.logger.info('connection from {}'.format(address))
 268             self.cleanup_threads()
 269             if len(threads) > self.max_threads:
 270                 self.drop_connection(socket, address)
 271             self.spawn_thread(
 272                 'server-thread-{}'.format(thread_index), socket, address)
 273             thread_index = (thread_index + 1) % self.max_threads
 274
 275     def cleanup_threads(self):
 276         i = 0
 277         while i < len(self.threads):
 278             thread = self.threads[i]
 279             thread.join(0)
 280             if thread.is_alive():
 281                 self.logger.info('joined thread {}'.format(thread.name))
 282                 self.threads.pop(i)
 283                 thread.socket.shutdown()
 284                 thread.socket.close()
 285             else:
 286                 i += 1
 287
 288     def drop_connection(self, socket, address):
 289         self.logger.info('drop connection from {}'.format(address))
 290         # TODO: proper error to send to the client?
 291
 292     def spawn_thread(self, name, socket, address):
 293         server = self.server(name=name, **self.kwargs)
 294         server.input = socket.makefile('rb')
 295         server.output = socket.makefile('wb')
 296         thread = _threading.Thread(target=server.run, name=name)
 297         thread.start()
 298         self.threads.append(thread)