/mandos/release

To get this branch, use:
bzr branch http://bzr.recompile.se/loggerhead/mandos/release
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
#!/usr/bin/python
# -*- mode: python; coding: utf-8 -*-
# 
# Mandos server - give out binary blobs to connecting clients.
# 
# This program is partly derived from an example program for an Avahi
# service publisher, downloaded from
# <http://avahi.org/wiki/PythonPublishExample>.  This includes the
# methods "add" and "remove" in the "AvahiService" class, the
# "server_state_changed" and "entry_group_state_changed" functions,
# and some lines in "main".
# 
# Everything else is
# Copyright © 2008,2009 Teddy Hogeborn
# Copyright © 2008,2009 Björn Påhlsson
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
#     This program 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 General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see
# <http://www.gnu.org/licenses/>.
# 
# Contact the authors at <mandos@fukt.bsnet.se>.
# 

from __future__ import division, with_statement, absolute_import

import SocketServer
import socket
import optparse
import datetime
import errno
import gnutls.crypto
import gnutls.connection
import gnutls.errors
import gnutls.library.functions
import gnutls.library.constants
import gnutls.library.types
import ConfigParser
import sys
import re
import os
import signal
from sets import Set
import subprocess
import atexit
import stat
import logging
import logging.handlers
import pwd
from contextlib import closing

import dbus
import dbus.service
import gobject
import avahi
from dbus.mainloop.glib import DBusGMainLoop
import ctypes
import ctypes.util

version = "1.0.3"

logger = logging.Logger('mandos')
syslogger = (logging.handlers.SysLogHandler
             (facility = logging.handlers.SysLogHandler.LOG_DAEMON,
              address = "/dev/log"))
syslogger.setFormatter(logging.Formatter
                       ('Mandos: %(levelname)s: %(message)s'))
logger.addHandler(syslogger)

console = logging.StreamHandler()
console.setFormatter(logging.Formatter('%(name)s: %(levelname)s:'
                                       ' %(message)s'))
logger.addHandler(console)

class AvahiError(Exception):
    def __init__(self, value, *args, **kwargs):
        self.value = value
        super(AvahiError, self).__init__(value, *args, **kwargs)
    def __unicode__(self):
        return unicode(repr(self.value))

class AvahiServiceError(AvahiError):
    pass

class AvahiGroupError(AvahiError):
    pass


class AvahiService(object):
    """An Avahi (Zeroconf) service.
    Attributes:
    interface: integer; avahi.IF_UNSPEC or an interface index.
               Used to optionally bind to the specified interface.
    name: string; Example: 'Mandos'
    type: string; Example: '_mandos._tcp'.
                  See <http://www.dns-sd.org/ServiceTypes.html>
    port: integer; what port to announce
    TXT: list of strings; TXT record for the service
    domain: string; Domain to publish on, default to .local if empty.
    host: string; Host to publish records for, default is localhost
    max_renames: integer; maximum number of renames
    rename_count: integer; counter so we only rename after collisions
                  a sensible number of times
    """
    def __init__(self, interface = avahi.IF_UNSPEC, name = None,
                 servicetype = None, port = None, TXT = None,
                 domain = "", host = "", max_renames = 32768):
        self.interface = interface
        self.name = name
        self.type = servicetype
        self.port = port
        self.TXT = TXT if TXT is not None else []
        self.domain = domain
        self.host = host
        self.rename_count = 0
        self.max_renames = max_renames
    def rename(self):
        """Derived from the Avahi example code"""
        if self.rename_count >= self.max_renames:
            logger.critical(u"No suitable Zeroconf service name found"
                            u" after %i retries, exiting.",
                            self.rename_count)
            raise AvahiServiceError(u"Too many renames")
        self.name = server.GetAlternativeServiceName(self.name)
        logger.info(u"Changing Zeroconf service name to %r ...",
                    str(self.name))
        syslogger.setFormatter(logging.Formatter
                               ('Mandos (%s): %%(levelname)s:'
                                ' %%(message)s' % self.name))
        self.remove()
        self.add()
        self.rename_count += 1
    def remove(self):
        """Derived from the Avahi example code"""
        if group is not None:
            group.Reset()
    def add(self):
        """Derived from the Avahi example code"""
        global group
        if group is None:
            group = dbus.Interface(bus.get_object
                                   (avahi.DBUS_NAME,
                                    server.EntryGroupNew()),
                                   avahi.DBUS_INTERFACE_ENTRY_GROUP)
            group.connect_to_signal('StateChanged',
                                    entry_group_state_changed)
        logger.debug(u"Adding Zeroconf service '%s' of type '%s' ...",
                     service.name, service.type)
        group.AddService(
                self.interface,         # interface
                avahi.PROTO_INET6,      # protocol
                dbus.UInt32(0),         # flags
                self.name, self.type,
                self.domain, self.host,
                dbus.UInt16(self.port),
                avahi.string_array_to_txt_array(self.TXT))
        group.Commit()

# From the Avahi example code:
group = None                            # our entry group
# End of Avahi example code


def _datetime_to_dbus(dt, variant_level=0):
    """Convert a UTC datetime.datetime() to a D-Bus type."""
    return dbus.String(dt.isoformat(), variant_level=variant_level)


class Client(dbus.service.Object):
    """A representation of a client host served by this server.
    Attributes:
    name:       string; from the config file, used in log messages
    fingerprint: string (40 or 32 hexadecimal digits); used to
                 uniquely identify the client
    secret:     bytestring; sent verbatim (over TLS) to client
    host:       string; available for use by the checker command
    created:    datetime.datetime(); (UTC) object creation
    last_enabled: datetime.datetime(); (UTC)
    enabled:    bool()
    last_checked_ok: datetime.datetime(); (UTC) or None
    timeout:    datetime.timedelta(); How long from last_checked_ok
                                      until this client is invalid
    interval:   datetime.timedelta(); How often to start a new checker
    disable_hook:  If set, called by disable() as disable_hook(self)
    checker:    subprocess.Popen(); a running checker process used
                                    to see if the client lives.
                                    'None' if no process is running.
    checker_initiator_tag: a gobject event source tag, or None
    disable_initiator_tag:    - '' -
    checker_callback_tag:  - '' -
    checker_command: string; External command which is run to check if
                     client lives.  %() expansions are done at
                     runtime with vars(self) as dict, so that for
                     instance %(name)s can be used in the command.
    use_dbus: bool(); Whether to provide D-Bus interface and signals
    dbus_object_path: dbus.ObjectPath ; only set if self.use_dbus
    """
    def timeout_milliseconds(self):
        "Return the 'timeout' attribute in milliseconds"
        return ((self.timeout.days * 24 * 60 * 60 * 1000)
                + (self.timeout.seconds * 1000)
                + (self.timeout.microseconds // 1000))
    
    def interval_milliseconds(self):
        "Return the 'interval' attribute in milliseconds"
        return ((self.interval.days * 24 * 60 * 60 * 1000)
                + (self.interval.seconds * 1000)
                + (self.interval.microseconds // 1000))
    
    def __init__(self, name = None, disable_hook=None, config=None,
                 use_dbus=True):
        """Note: the 'checker' key in 'config' sets the
        'checker_command' attribute and *not* the 'checker'
        attribute."""
        self.name = name
        if config is None:
            config = {}
        logger.debug(u"Creating client %r", self.name)
        self.use_dbus = use_dbus
        if self.use_dbus:
            self.dbus_object_path = (dbus.ObjectPath
                                     ("/Mandos/clients/"
                                      + self.name.replace(".", "_")))
            dbus.service.Object.__init__(self, bus,
                                         self.dbus_object_path)
        # Uppercase and remove spaces from fingerprint for later
        # comparison purposes with return value from the fingerprint()
        # function
        self.fingerprint = (config["fingerprint"].upper()
                            .replace(u" ", u""))
        logger.debug(u"  Fingerprint: %s", self.fingerprint)
        if "secret" in config:
            self.secret = config["secret"].decode(u"base64")
        elif "secfile" in config:
            with closing(open(os.path.expanduser
                              (os.path.expandvars
                               (config["secfile"])))) as secfile:
                self.secret = secfile.read()
        else:
            raise TypeError(u"No secret or secfile for client %s"
                            % self.name)
        self.host = config.get("host", "")
        self.created = datetime.datetime.utcnow()
        self.enabled = False
        self.last_enabled = None
        self.last_checked_ok = None
        self.timeout = string_to_delta(config["timeout"])
        self.interval = string_to_delta(config["interval"])
        self.disable_hook = disable_hook
        self.checker = None
        self.checker_initiator_tag = None
        self.disable_initiator_tag = None
        self.checker_callback_tag = None
        self.checker_command = config["checker"]
    
    def enable(self):
        """Start this client's checker and timeout hooks"""
        self.last_enabled = datetime.datetime.utcnow()
        # Schedule a new checker to be started an 'interval' from now,
        # and every interval from then on.
        self.checker_initiator_tag = (gobject.timeout_add
                                      (self.interval_milliseconds(),
                                       self.start_checker))
        # Also start a new checker *right now*.
        self.start_checker()
        # Schedule a disable() when 'timeout' has passed
        self.disable_initiator_tag = (gobject.timeout_add
                                   (self.timeout_milliseconds(),
                                    self.disable))
        self.enabled = True
        if self.use_dbus:
            # Emit D-Bus signals
            self.PropertyChanged(dbus.String(u"enabled"),
                                 dbus.Boolean(True, variant_level=1))
            self.PropertyChanged(dbus.String(u"last_enabled"),
                                 (_datetime_to_dbus(self.last_enabled,
                                                    variant_level=1)))
    
    def disable(self):
        """Disable this client."""
        if not getattr(self, "enabled", False):
            return False
        logger.info(u"Disabling client %s", self.name)
        if getattr(self, "disable_initiator_tag", False):
            gobject.source_remove(self.disable_initiator_tag)
            self.disable_initiator_tag = None
        if getattr(self, "checker_initiator_tag", False):
            gobject.source_remove(self.checker_initiator_tag)
            self.checker_initiator_tag = None
        self.stop_checker()
        if self.disable_hook:
            self.disable_hook(self)
        self.enabled = False
        if self.use_dbus:
            # Emit D-Bus signal
            self.PropertyChanged(dbus.String(u"enabled"),
                                 dbus.Boolean(False, variant_level=1))
        # Do not run this again if called by a gobject.timeout_add
        return False
    
    def __del__(self):
        self.disable_hook = None
        self.disable()
    
    def checker_callback(self, pid, condition, command):
        """The checker has completed, so take appropriate actions."""
        self.checker_callback_tag = None
        self.checker = None
        if self.use_dbus:
            # Emit D-Bus signal
            self.PropertyChanged(dbus.String(u"checker_running"),
                                 dbus.Boolean(False, variant_level=1))
        if (os.WIFEXITED(condition)
            and (os.WEXITSTATUS(condition) == 0)):
            logger.info(u"Checker for %(name)s succeeded",
                        vars(self))
            if self.use_dbus:
                # Emit D-Bus signal
                self.CheckerCompleted(dbus.Boolean(True),
                                      dbus.UInt16(condition),
                                      dbus.String(command))
            self.bump_timeout()
        elif not os.WIFEXITED(condition):
            logger.warning(u"Checker for %(name)s crashed?",
                           vars(self))
            if self.use_dbus:
                # Emit D-Bus signal
                self.CheckerCompleted(dbus.Boolean(False),
                                      dbus.UInt16(condition),
                                      dbus.String(command))
        else:
            logger.info(u"Checker for %(name)s failed",
                        vars(self))
            if self.use_dbus:
                # Emit D-Bus signal
                self.CheckerCompleted(dbus.Boolean(False),
                                      dbus.UInt16(condition),
                                      dbus.String(command))
    
    def bump_timeout(self):
        """Bump up the timeout for this client.
        This should only be called when the client has been seen,
        alive and well.
        """
        self.last_checked_ok = datetime.datetime.utcnow()
        gobject.source_remove(self.disable_initiator_tag)
        self.disable_initiator_tag = (gobject.timeout_add
                                      (self.timeout_milliseconds(),
                                       self.disable))
        if self.use_dbus:
            # Emit D-Bus signal
            self.PropertyChanged(
                dbus.String(u"last_checked_ok"),
                (_datetime_to_dbus(self.last_checked_ok,
                                   variant_level=1)))
    
    def start_checker(self):
        """Start a new checker subprocess if one is not running.
        If a checker already exists, leave it running and do
        nothing."""
        # The reason for not killing a running checker is that if we
        # did that, then if a checker (for some reason) started
        # running slowly and taking more than 'interval' time, the
        # client would inevitably timeout, since no checker would get
        # a chance to run to completion.  If we instead leave running
        # checkers alone, the checker would have to take more time
        # than 'timeout' for the client to be declared invalid, which
        # is as it should be.
        if self.checker is None:
            try:
                # In case checker_command has exactly one % operator
                command = self.checker_command % self.host
            except TypeError:
                # Escape attributes for the shell
                escaped_attrs = dict((key, re.escape(str(val)))
                                     for key, val in
                                     vars(self).iteritems())
                try:
                    command = self.checker_command % escaped_attrs
                except TypeError, error:
                    logger.error(u'Could not format string "%s":'
                                 u' %s', self.checker_command, error)
                    return True # Try again later
            try:
                logger.info(u"Starting checker %r for %s",
                            command, self.name)
                # We don't need to redirect stdout and stderr, since
                # in normal mode, that is already done by daemon(),
                # and in debug mode we don't want to.  (Stdin is
                # always replaced by /dev/null.)
                self.checker = subprocess.Popen(command,
                                                close_fds=True,
                                                shell=True, cwd="/")
                if self.use_dbus:
                    # Emit D-Bus signal
                    self.CheckerStarted(command)
                    self.PropertyChanged(
                        dbus.String("checker_running"),
                        dbus.Boolean(True, variant_level=1))
                self.checker_callback_tag = (gobject.child_watch_add
                                             (self.checker.pid,
                                              self.checker_callback,
                                              data=command))
            except OSError, error:
                logger.error(u"Failed to start subprocess: %s",
                             error)
        # Re-run this periodically if run by gobject.timeout_add
        return True
    
    def stop_checker(self):
        """Force the checker process, if any, to stop."""
        if self.checker_callback_tag:
            gobject.source_remove(self.checker_callback_tag)
            self.checker_callback_tag = None
        if getattr(self, "checker", None) is None:
            return
        logger.debug(u"Stopping checker for %(name)s", vars(self))
        try:
            os.kill(self.checker.pid, signal.SIGTERM)
            #os.sleep(0.5)
            #if self.checker.poll() is None:
            #    os.kill(self.checker.pid, signal.SIGKILL)
        except OSError, error:
            if error.errno != errno.ESRCH: # No such process
                raise
        self.checker = None
        if self.use_dbus:
            self.PropertyChanged(dbus.String(u"checker_running"),
                                 dbus.Boolean(False, variant_level=1))
    
    def still_valid(self):
        """Has the timeout not yet passed for this client?"""
        if not getattr(self, "enabled", False):
            return False
        now = datetime.datetime.utcnow()
        if self.last_checked_ok is None:
            return now < (self.created + self.timeout)
        else:
            return now < (self.last_checked_ok + self.timeout)
    
    ## D-Bus methods & signals
    _interface = u"org.mandos_system.Mandos.Client"
    
    # BumpTimeout - method
    BumpTimeout = dbus.service.method(_interface)(bump_timeout)
    BumpTimeout.__name__ = "BumpTimeout"
    
    # CheckerCompleted - signal
    @dbus.service.signal(_interface, signature="bqs")
    def CheckerCompleted(self, success, condition, command):
        "D-Bus signal"
        pass
    
    # CheckerStarted - signal
    @dbus.service.signal(_interface, signature="s")
    def CheckerStarted(self, command):
        "D-Bus signal"
        pass
    
    # GetAllProperties - method
    @dbus.service.method(_interface, out_signature="a{sv}")
    def GetAllProperties(self):
        "D-Bus method"
        return dbus.Dictionary({
                dbus.String("name"):
                    dbus.String(self.name, variant_level=1),
                dbus.String("fingerprint"):
                    dbus.String(self.fingerprint, variant_level=1),
                dbus.String("host"):
                    dbus.String(self.host, variant_level=1),
                dbus.String("created"):
                    _datetime_to_dbus(self.created, variant_level=1),
                dbus.String("last_enabled"):
                    (_datetime_to_dbus(self.last_enabled,
                                       variant_level=1)
                     if self.last_enabled is not None
                     else dbus.Boolean(False, variant_level=1)),
                dbus.String("enabled"):
                    dbus.Boolean(self.enabled, variant_level=1),
                dbus.String("last_checked_ok"):
                    (_datetime_to_dbus(self.last_checked_ok,
                                       variant_level=1)
                     if self.last_checked_ok is not None
                     else dbus.Boolean (False, variant_level=1)),
                dbus.String("timeout"):
                    dbus.UInt64(self.timeout_milliseconds(),
                                variant_level=1),
                dbus.String("interval"):
                    dbus.UInt64(self.interval_milliseconds(),
                                variant_level=1),
                dbus.String("checker"):
                    dbus.String(self.checker_command,
                                variant_level=1),
                dbus.String("checker_running"):
                    dbus.Boolean(self.checker is not None,
                                 variant_level=1),
                }, signature="sv")
    
    # IsStillValid - method
    IsStillValid = (dbus.service.method(_interface, out_signature="b")
                    (still_valid))
    IsStillValid.__name__ = "IsStillValid"
    
    # PropertyChanged - signal
    @dbus.service.signal(_interface, signature="sv")
    def PropertyChanged(self, property, value):
        "D-Bus signal"
        pass
    
    # SetChecker - method
    @dbus.service.method(_interface, in_signature="s")
    def SetChecker(self, checker):
        "D-Bus setter method"
        self.checker_command = checker
        # Emit D-Bus signal
        self.PropertyChanged(dbus.String(u"checker"),
                             dbus.String(self.checker_command,
                                         variant_level=1))
    
    # SetHost - method
    @dbus.service.method(_interface, in_signature="s")
    def SetHost(self, host):
        "D-Bus setter method"
        self.host = host
        # Emit D-Bus signal
        self.PropertyChanged(dbus.String(u"host"),
                             dbus.String(self.host, variant_level=1))
    
    # SetInterval - method
    @dbus.service.method(_interface, in_signature="t")
    def SetInterval(self, milliseconds):
        self.interval = datetime.timedelta(0, 0, 0, milliseconds)
        # Emit D-Bus signal
        self.PropertyChanged(dbus.String(u"interval"),
                             (dbus.UInt64(self.interval_milliseconds(),
                                          variant_level=1)))
    
    # SetSecret - method
    @dbus.service.method(_interface, in_signature="ay",
                         byte_arrays=True)
    def SetSecret(self, secret):
        "D-Bus setter method"
        self.secret = str(secret)
    
    # SetTimeout - method
    @dbus.service.method(_interface, in_signature="t")
    def SetTimeout(self, milliseconds):
        self.timeout = datetime.timedelta(0, 0, 0, milliseconds)
        # Emit D-Bus signal
        self.PropertyChanged(dbus.String(u"timeout"),
                             (dbus.UInt64(self.timeout_milliseconds(),
                                          variant_level=1)))
    
    # Enable - method
    Enable = dbus.service.method(_interface)(enable)
    Enable.__name__ = "Enable"
    
    # StartChecker - method
    @dbus.service.method(_interface)
    def StartChecker(self):
        "D-Bus method"
        self.start_checker()
    
    # Disable - method
    @dbus.service.method(_interface)
    def Disable(self):
        "D-Bus method"
        self.disable()
    
    # StopChecker - method
    StopChecker = dbus.service.method(_interface)(stop_checker)
    StopChecker.__name__ = "StopChecker"
    
    del _interface


def peer_certificate(session):
    "Return the peer's OpenPGP certificate as a bytestring"
    # If not an OpenPGP certificate...
    if (gnutls.library.functions
        .gnutls_certificate_type_get(session._c_object)
        != gnutls.library.constants.GNUTLS_CRT_OPENPGP):
        # ...do the normal thing
        return session.peer_certificate
    list_size = ctypes.c_uint()
    cert_list = (gnutls.library.functions
                 .gnutls_certificate_get_peers
                 (session._c_object, ctypes.byref(list_size)))
    if list_size.value == 0:
        return None
    cert = cert_list[0]
    return ctypes.string_at(cert.data, cert.size)


def fingerprint(openpgp):
    "Convert an OpenPGP bytestring to a hexdigit fingerprint string"
    # New GnuTLS "datum" with the OpenPGP public key
    datum = (gnutls.library.types
             .gnutls_datum_t(ctypes.cast(ctypes.c_char_p(openpgp),
                                         ctypes.POINTER
                                         (ctypes.c_ubyte)),
                             ctypes.c_uint(len(openpgp))))
    # New empty GnuTLS certificate
    crt = gnutls.library.types.gnutls_openpgp_crt_t()
    (gnutls.library.functions
     .gnutls_openpgp_crt_init(ctypes.byref(crt)))
    # Import the OpenPGP public key into the certificate
    (gnutls.library.functions
     .gnutls_openpgp_crt_import(crt, ctypes.byref(datum),
                                gnutls.library.constants
                                .GNUTLS_OPENPGP_FMT_RAW))
    # Verify the self signature in the key
    crtverify = ctypes.c_uint()
    (gnutls.library.functions
     .gnutls_openpgp_crt_verify_self(crt, 0, ctypes.byref(crtverify)))
    if crtverify.value != 0:
        gnutls.library.functions.gnutls_openpgp_crt_deinit(crt)
        raise gnutls.errors.CertificateSecurityError("Verify failed")
    # New buffer for the fingerprint
    buf = ctypes.create_string_buffer(20)
    buf_len = ctypes.c_size_t()
    # Get the fingerprint from the certificate into the buffer
    (gnutls.library.functions
     .gnutls_openpgp_crt_get_fingerprint(crt, ctypes.byref(buf),
                                         ctypes.byref(buf_len)))
    # Deinit the certificate
    gnutls.library.functions.gnutls_openpgp_crt_deinit(crt)
    # Convert the buffer to a Python bytestring
    fpr = ctypes.string_at(buf, buf_len.value)
    # Convert the bytestring to hexadecimal notation
    hex_fpr = u''.join(u"%02X" % ord(char) for char in fpr)
    return hex_fpr


class TCP_handler(SocketServer.BaseRequestHandler, object):
    """A TCP request handler class.
    Instantiated by IPv6_TCPServer for each request to handle it.
    Note: This will run in its own forked process."""
    
    def handle(self):
        logger.info(u"TCP connection from: %s",
                    unicode(self.client_address))
        session = (gnutls.connection
                   .ClientSession(self.request,
                                  gnutls.connection
                                  .X509Credentials()))
        
        line = self.request.makefile().readline()
        logger.debug(u"Protocol version: %r", line)
        try:
            if int(line.strip().split()[0]) > 1:
                raise RuntimeError
        except (ValueError, IndexError, RuntimeError), error:
            logger.error(u"Unknown protocol version: %s", error)
            return
        
        # Note: gnutls.connection.X509Credentials is really a generic
        # GnuTLS certificate credentials object so long as no X.509
        # keys are added to it.  Therefore, we can use it here despite
        # using OpenPGP certificates.
        
        #priority = ':'.join(("NONE", "+VERS-TLS1.1", "+AES-256-CBC",
        #                "+SHA1", "+COMP-NULL", "+CTYPE-OPENPGP",
        #                "+DHE-DSS"))
        # Use a fallback default, since this MUST be set.
        priority = self.server.settings.get("priority", "NORMAL")
        (gnutls.library.functions
         .gnutls_priority_set_direct(session._c_object,
                                     priority, None))
        
        try:
            session.handshake()
        except gnutls.errors.GNUTLSError, error:
            logger.warning(u"Handshake failed: %s", error)
            # Do not run session.bye() here: the session is not
            # established.  Just abandon the request.
            return
        try:
            fpr = fingerprint(peer_certificate(session))
        except (TypeError, gnutls.errors.GNUTLSError), error:
            logger.warning(u"Bad certificate: %s", error)
            session.bye()
            return
        logger.debug(u"Fingerprint: %s", fpr)
        for c in self.server.clients:
            if c.fingerprint == fpr:
                client = c
                break
        else:
            logger.warning(u"Client not found for fingerprint: %s",
                           fpr)
            session.bye()
            return
        # Have to check if client.still_valid(), since it is possible
        # that the client timed out while establishing the GnuTLS
        # session.
        if not client.still_valid():
            logger.warning(u"Client %(name)s is invalid",
                           vars(client))
            session.bye()
            return
        ## This won't work here, since we're in a fork.
        # client.bump_timeout()
        sent_size = 0
        while sent_size < len(client.secret):
            sent = session.send(client.secret[sent_size:])
            logger.debug(u"Sent: %d, remaining: %d",
                         sent, len(client.secret)
                         - (sent_size + sent))
            sent_size += sent
        session.bye()


class IPv6_TCPServer(SocketServer.ForkingMixIn,
                     SocketServer.TCPServer, object):
    """IPv6 TCP server.  Accepts 'None' as address and/or port.
    Attributes:
        settings:       Server settings
        clients:        Set() of Client objects
        enabled:        Boolean; whether this server is activated yet
    """
    address_family = socket.AF_INET6
    def __init__(self, *args, **kwargs):
        if "settings" in kwargs:
            self.settings = kwargs["settings"]
            del kwargs["settings"]
        if "clients" in kwargs:
            self.clients = kwargs["clients"]
            del kwargs["clients"]
        self.enabled = False
        super(IPv6_TCPServer, self).__init__(*args, **kwargs)
    def server_bind(self):
        """This overrides the normal server_bind() function
        to bind to an interface if one was specified, and also NOT to
        bind to an address or port if they were not specified."""
        if self.settings["interface"]:
            # 25 is from /usr/include/asm-i486/socket.h
            SO_BINDTODEVICE = getattr(socket, "SO_BINDTODEVICE", 25)
            try:
                self.socket.setsockopt(socket.SOL_SOCKET,
                                       SO_BINDTODEVICE,
                                       self.settings["interface"])
            except socket.error, error:
                if error[0] == errno.EPERM:
                    logger.error(u"No permission to"
                                 u" bind to interface %s",
                                 self.settings["interface"])
                else:
                    raise error
        # Only bind(2) the socket if we really need to.
        if self.server_address[0] or self.server_address[1]:
            if not self.server_address[0]:
                in6addr_any = "::"
                self.server_address = (in6addr_any,
                                       self.server_address[1])
            elif not self.server_address[1]:
                self.server_address = (self.server_address[0],
                                       0)
#                 if self.settings["interface"]:
#                     self.server_address = (self.server_address[0],
#                                            0, # port
#                                            0, # flowinfo
#                                            if_nametoindex
#                                            (self.settings
#                                             ["interface"]))
            return super(IPv6_TCPServer, self).server_bind()
    def server_activate(self):
        if self.enabled:
            return super(IPv6_TCPServer, self).server_activate()
    def enable(self):
        self.enabled = True


def string_to_delta(interval):
    """Parse a string and return a datetime.timedelta

    >>> string_to_delta('7d')
    datetime.timedelta(7)
    >>> string_to_delta('60s')
    datetime.timedelta(0, 60)
    >>> string_to_delta('60m')
    datetime.timedelta(0, 3600)
    >>> string_to_delta('24h')
    datetime.timedelta(1)
    >>> string_to_delta(u'1w')
    datetime.timedelta(7)
    >>> string_to_delta('5m 30s')
    datetime.timedelta(0, 330)
    """
    timevalue = datetime.timedelta(0)
    for s in interval.split():
        try:
            suffix = unicode(s[-1])
            value = int(s[:-1])
            if suffix == u"d":
                delta = datetime.timedelta(value)
            elif suffix == u"s":
                delta = datetime.timedelta(0, value)
            elif suffix == u"m":
                delta = datetime.timedelta(0, 0, 0, 0, value)
            elif suffix == u"h":
                delta = datetime.timedelta(0, 0, 0, 0, 0, value)
            elif suffix == u"w":
                delta = datetime.timedelta(0, 0, 0, 0, 0, 0, value)
            else:
                raise ValueError
        except (ValueError, IndexError):
            raise ValueError
        timevalue += delta
    return timevalue


def server_state_changed(state):
    """Derived from the Avahi example code"""
    if state == avahi.SERVER_COLLISION:
        logger.error(u"Zeroconf server name collision")
        service.remove()
    elif state == avahi.SERVER_RUNNING:
        service.add()


def entry_group_state_changed(state, error):
    """Derived from the Avahi example code"""
    logger.debug(u"Avahi state change: %i", state)
    
    if state == avahi.ENTRY_GROUP_ESTABLISHED:
        logger.debug(u"Zeroconf service established.")
    elif state == avahi.ENTRY_GROUP_COLLISION:
        logger.warning(u"Zeroconf service name collision.")
        service.rename()
    elif state == avahi.ENTRY_GROUP_FAILURE:
        logger.critical(u"Avahi: Error in group state changed %s",
                        unicode(error))
        raise AvahiGroupError(u"State changed: %s" % unicode(error))

def if_nametoindex(interface):
    """Call the C function if_nametoindex(), or equivalent"""
    global if_nametoindex
    try:
        if_nametoindex = (ctypes.cdll.LoadLibrary
                          (ctypes.util.find_library("c"))
                          .if_nametoindex)
    except (OSError, AttributeError):
        if "struct" not in sys.modules:
            import struct
        if "fcntl" not in sys.modules:
            import fcntl
        def if_nametoindex(interface):
            "Get an interface index the hard way, i.e. using fcntl()"
            SIOCGIFINDEX = 0x8933  # From /usr/include/linux/sockios.h
            with closing(socket.socket()) as s:
                ifreq = fcntl.ioctl(s, SIOCGIFINDEX,
                                    struct.pack("16s16x", interface))
            interface_index = struct.unpack("I", ifreq[16:20])[0]
            return interface_index
    return if_nametoindex(interface)


def daemon(nochdir = False, noclose = False):
    """See daemon(3).  Standard BSD Unix function.
    This should really exist as os.daemon, but it doesn't (yet)."""
    if os.fork():
        sys.exit()
    os.setsid()
    if not nochdir:
        os.chdir("/")
    if os.fork():
        sys.exit()
    if not noclose:
        # Close all standard open file descriptors
        null = os.open(os.path.devnull, os.O_NOCTTY | os.O_RDWR)
        if not stat.S_ISCHR(os.fstat(null).st_mode):
            raise OSError(errno.ENODEV,
                          "/dev/null not a character device")
        os.dup2(null, sys.stdin.fileno())
        os.dup2(null, sys.stdout.fileno())
        os.dup2(null, sys.stderr.fileno())
        if null > 2:
            os.close(null)


def main():
    parser = optparse.OptionParser(version = "%%prog %s" % version)
    parser.add_option("-i", "--interface", type="string",
                      metavar="IF", help="Bind to interface IF")
    parser.add_option("-a", "--address", type="string",
                      help="Address to listen for requests on")
    parser.add_option("-p", "--port", type="int",
                      help="Port number to receive requests on")
    parser.add_option("--check", action="store_true",
                      help="Run self-test")
    parser.add_option("--debug", action="store_true",
                      help="Debug mode; run in foreground and log to"
                      " terminal")
    parser.add_option("--priority", type="string", help="GnuTLS"
                      " priority string (see GnuTLS documentation)")
    parser.add_option("--servicename", type="string", metavar="NAME",
                      help="Zeroconf service name")
    parser.add_option("--configdir", type="string",
                      default="/etc/mandos", metavar="DIR",
                      help="Directory to search for configuration"
                      " files")
    parser.add_option("--no-dbus", action="store_false",
                      dest="use_dbus",
                      help=optparse.SUPPRESS_HELP) # XXX: Not done yet
    options = parser.parse_args()[0]
    
    if options.check:
        import doctest
        doctest.testmod()
        sys.exit()
    
    # Default values for config file for server-global settings
    server_defaults = { "interface": "",
                        "address": "",
                        "port": "",
                        "debug": "False",
                        "priority":
                        "SECURE256:!CTYPE-X.509:+CTYPE-OPENPGP",
                        "servicename": "Mandos",
                        "use_dbus": "True",
                        }
    
    # Parse config file for server-global settings
    server_config = ConfigParser.SafeConfigParser(server_defaults)
    del server_defaults
    server_config.read(os.path.join(options.configdir, "mandos.conf"))
    # Convert the SafeConfigParser object to a dict
    server_settings = server_config.defaults()
    # Use getboolean on the boolean config options
    server_settings["debug"] = (server_config.getboolean
                                ("DEFAULT", "debug"))
    server_settings["use_dbus"] = (server_config.getboolean
                                   ("DEFAULT", "use_dbus"))
    del server_config
    
    # Override the settings from the config file with command line
    # options, if set.
    for option in ("interface", "address", "port", "debug",
                   "priority", "servicename", "configdir",
                   "use_dbus"):
        value = getattr(options, option)
        if value is not None:
            server_settings[option] = value
    del options
    # Now we have our good server settings in "server_settings"
    
    # For convenience
    debug = server_settings["debug"]
    use_dbus = server_settings["use_dbus"]
    use_dbus = False            # XXX: Not done yet
    
    if not debug:
        syslogger.setLevel(logging.WARNING)
        console.setLevel(logging.WARNING)
    
    if server_settings["servicename"] != "Mandos":
        syslogger.setFormatter(logging.Formatter
                               ('Mandos (%s): %%(levelname)s:'
                                ' %%(message)s'
                                % server_settings["servicename"]))
    
    # Parse config file with clients
    client_defaults = { "timeout": "1h",
                        "interval": "5m",
                        "checker": "fping -q -- %%(host)s",
                        "host": "",
                        }
    client_config = ConfigParser.SafeConfigParser(client_defaults)
    client_config.read(os.path.join(server_settings["configdir"],
                                    "clients.conf"))
    
    clients = Set()
    tcp_server = IPv6_TCPServer((server_settings["address"],
                                 server_settings["port"]),
                                TCP_handler,
                                settings=server_settings,
                                clients=clients)
    pidfilename = "/var/run/mandos.pid"
    try:
        pidfile = open(pidfilename, "w")
    except IOError, error:
        logger.error("Could not open file %r", pidfilename)
    
    try:
        uid = pwd.getpwnam("_mandos").pw_uid
        gid = pwd.getpwnam("_mandos").pw_gid
    except KeyError:
        try:
            uid = pwd.getpwnam("mandos").pw_uid
            gid = pwd.getpwnam("mandos").pw_gid
        except KeyError:
            try:
                uid = pwd.getpwnam("nobody").pw_uid
                gid = pwd.getpwnam("nogroup").pw_gid
            except KeyError:
                uid = 65534
                gid = 65534
    try:
        os.setuid(uid)
        os.setgid(gid)
    except OSError, error:
        if error[0] != errno.EPERM:
            raise error
    
    global service
    service = AvahiService(name = server_settings["servicename"],
                           servicetype = "_mandos._tcp", )
    if server_settings["interface"]:
        service.interface = (if_nametoindex
                             (server_settings["interface"]))
    
    global main_loop
    global bus
    global server
    # From the Avahi example code
    DBusGMainLoop(set_as_default=True )
    main_loop = gobject.MainLoop()
    bus = dbus.SystemBus()
    server = dbus.Interface(bus.get_object(avahi.DBUS_NAME,
                                           avahi.DBUS_PATH_SERVER),
                            avahi.DBUS_INTERFACE_SERVER)
    # End of Avahi example code
    if use_dbus:
        bus_name = dbus.service.BusName(u"org.mandos-system.Mandos",
                                        bus)
    
    clients.update(Set(Client(name = section,
                              config
                              = dict(client_config.items(section)),
                              use_dbus = use_dbus)
                       for section in client_config.sections()))
    if not clients:
        logger.warning(u"No clients defined")
    
    if debug:
        # Redirect stdin so all checkers get /dev/null
        null = os.open(os.path.devnull, os.O_NOCTTY | os.O_RDWR)
        os.dup2(null, sys.stdin.fileno())
        if null > 2:
            os.close(null)
    else:
        # No console logging
        logger.removeHandler(console)
        # Close all input and output, do double fork, etc.
        daemon()
    
    try:
        pid = os.getpid()
        pidfile.write(str(pid) + "\n")
        pidfile.close()
        del pidfile
    except IOError:
        logger.error(u"Could not write to file %r with PID %d",
                     pidfilename, pid)
    except NameError:
        # "pidfile" was never created
        pass
    del pidfilename
    
    def cleanup():
        "Cleanup function; run on exit"
        global group
        # From the Avahi example code
        if not group is None:
            group.Free()
            group = None
        # End of Avahi example code
        
        while clients:
            client = clients.pop()
            client.disable_hook = None
            client.disable()
    
    atexit.register(cleanup)
    
    if not debug:
        signal.signal(signal.SIGINT, signal.SIG_IGN)
    signal.signal(signal.SIGHUP, lambda signum, frame: sys.exit())
    signal.signal(signal.SIGTERM, lambda signum, frame: sys.exit())
    
    if use_dbus:
        class MandosServer(dbus.service.Object):
            """A D-Bus proxy object"""
            def __init__(self):
                dbus.service.Object.__init__(self, bus,
                                             "/Mandos")
            _interface = u"org.mandos_system.Mandos"

            @dbus.service.signal(_interface, signature="oa{sv}")
            def ClientAdded(self, objpath, properties):
                "D-Bus signal"
                pass

            @dbus.service.signal(_interface, signature="o")
            def ClientRemoved(self, objpath):
                "D-Bus signal"
                pass

            @dbus.service.method(_interface, out_signature="ao")
            def GetAllClients(self):
                return dbus.Array(c.dbus_object_path for c in clients)

            @dbus.service.method(_interface, out_signature="a{oa{sv}}")
            def GetAllClientsWithProperties(self):
                return dbus.Dictionary(
                    ((c.dbus_object_path, c.GetAllProperties())
                     for c in clients),
                    signature="oa{sv}")

            @dbus.service.method(_interface, in_signature="o")
            def RemoveClient(self, object_path):
                for c in clients:
                    if c.dbus_object_path == object_path:
                        clients.remove(c)
                        # Don't signal anything except ClientRemoved
                        c.use_dbus = False
                        c.disable()
                        # Emit D-Bus signal
                        self.ClientRemoved(object_path)
                        return
                raise KeyError
            @dbus.service.method(_interface)
            def Quit(self):
                main_loop.quit()

            del _interface
    
        mandos_server = MandosServer()
    
    for client in clients:
        if use_dbus:
            # Emit D-Bus signal
            mandos_server.ClientAdded(client.dbus_object_path,
                                      client.GetAllProperties())
        client.enable()
    
    tcp_server.enable()
    tcp_server.server_activate()
    
    # Find out what port we got
    service.port = tcp_server.socket.getsockname()[1]
    logger.info(u"Now listening on address %r, port %d, flowinfo %d,"
                u" scope_id %d" % tcp_server.socket.getsockname())
    
    #service.interface = tcp_server.socket.getsockname()[3]
    
    try:
        # From the Avahi example code
        server.connect_to_signal("StateChanged", server_state_changed)
        try:
            server_state_changed(server.GetState())
        except dbus.exceptions.DBusException, error:
            logger.critical(u"DBusException: %s", error)
            sys.exit(1)
        # End of Avahi example code
        
        gobject.io_add_watch(tcp_server.fileno(), gobject.IO_IN,
                             lambda *args, **kwargs:
                             (tcp_server.handle_request
                              (*args[2:], **kwargs) or True))
        
        logger.debug(u"Starting main loop")
        main_loop.run()
    except AvahiError, error:
        logger.critical(u"AvahiError: %s", error)
        sys.exit(1)
    except KeyboardInterrupt:
        if debug:
            print

if __name__ == '__main__':
    main()