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server.py
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# This program is partly derived from an example program for an Avahi
7
7
# service publisher, downloaded from
8
8
# <http://avahi.org/wiki/PythonPublishExample>.  This includes the
9
 
# methods "add" and "remove" in the "AvahiService" class, the
10
 
# "server_state_changed" and "entry_group_state_changed" functions,
11
 
# and some lines in "main".
 
9
# following functions: "AvahiService.add", "AvahiService.remove",
 
10
# "server_state_changed", "entry_group_state_changed", and some lines
 
11
# in "main".
12
12
# 
13
13
# Everything else is
14
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# Copyright © 2007-2008 Teddy Hogeborn & Björn Påhlsson
61
61
from dbus.mainloop.glib import DBusGMainLoop
62
62
import ctypes
63
63
 
64
 
version = "1.0"
 
64
# Brief description of the operation of this program:
 
65
# 
 
66
# This server announces itself as a Zeroconf service.  Connecting
 
67
# clients use the TLS protocol, with the unusual quirk that this
 
68
# server program acts as a TLS "client" while a connecting client acts
 
69
# as a TLS "server".  The client (acting as a TLS "server") must
 
70
# supply an OpenPGP certificate, and the fingerprint of this
 
71
# certificate is used by this server to look up (in a list read from a
 
72
# file at start time) which binary blob to give the client.  No other
 
73
# authentication or authorization is done by this server.
 
74
 
65
75
 
66
76
logger = logging.Logger('mandos')
67
77
syslogger = logging.handlers.SysLogHandler\
68
 
            (facility = logging.handlers.SysLogHandler.LOG_DAEMON,
69
 
             address = "/dev/log")
 
78
            (facility = logging.handlers.SysLogHandler.LOG_DAEMON)
70
79
syslogger.setFormatter(logging.Formatter\
71
 
                        ('Mandos: %(levelname)s: %(message)s'))
 
80
                        ('%(levelname)s: %(message)s'))
72
81
logger.addHandler(syslogger)
 
82
del syslogger
73
83
 
74
 
console = logging.StreamHandler()
75
 
console.setFormatter(logging.Formatter('%(name)s: %(levelname)s:'
76
 
                                       ' %(message)s'))
77
 
logger.addHandler(console)
78
84
 
79
85
class AvahiError(Exception):
80
86
    def __init__(self, value):
90
96
 
91
97
 
92
98
class AvahiService(object):
93
 
    """An Avahi (Zeroconf) service.
94
 
    Attributes:
 
99
    """
95
100
    interface: integer; avahi.IF_UNSPEC or an interface index.
96
101
               Used to optionally bind to the specified interface.
97
 
    name: string; Example: 'Mandos'
98
 
    type: string; Example: '_mandos._tcp'.
99
 
                  See <http://www.dns-sd.org/ServiceTypes.html>
100
 
    port: integer; what port to announce
101
 
    TXT: list of strings; TXT record for the service
102
 
    domain: string; Domain to publish on, default to .local if empty.
103
 
    host: string; Host to publish records for, default is localhost
104
 
    max_renames: integer; maximum number of renames
105
 
    rename_count: integer; counter so we only rename after collisions
106
 
                  a sensible number of times
 
102
    name = string; Example: "Mandos"
 
103
    type = string; Example: "_mandos._tcp".
 
104
                   See <http://www.dns-sd.org/ServiceTypes.html>
 
105
    port = integer; what port to announce
 
106
    TXT = list of strings; TXT record for the service
 
107
    domain = string; Domain to publish on, default to .local if empty.
 
108
    host = string; Host to publish records for, default to localhost
 
109
                   if empty.
 
110
    max_renames = integer; maximum number of renames
 
111
    rename_count = integer; counter so we only rename after collisions
 
112
                   a sensible number of times
107
113
    """
108
114
    def __init__(self, interface = avahi.IF_UNSPEC, name = None,
109
115
                 type = None, port = None, TXT = None, domain = "",
110
 
                 host = "", max_renames = 32768):
 
116
                 host = "", max_renames = 12):
 
117
        """An Avahi (Zeroconf) service. """
111
118
        self.interface = interface
112
119
        self.name = name
113
120
        self.type = type
126
133
                            u" retries, exiting.", rename_count)
127
134
            raise AvahiServiceError("Too many renames")
128
135
        name = server.GetAlternativeServiceName(name)
129
 
        logger.error(u"Changing name to %r ...", name)
130
 
        syslogger.setFormatter(logging.Formatter\
131
 
                               ('Mandos (%s): %%(levelname)s:'
132
 
                               ' %%(message)s' % name))
 
136
        logger.notice(u"Changing name to %r ...", name)
133
137
        self.remove()
134
138
        self.add()
135
139
        self.rename_count += 1
171
175
    fingerprint: string (40 or 32 hexadecimal digits); used to
172
176
                 uniquely identify the client
173
177
    secret:    bytestring; sent verbatim (over TLS) to client
174
 
    host:      string; available for use by the checker command
 
178
    fqdn:      string (FQDN); available for use by the checker command
175
179
    created:   datetime.datetime(); object creation, not client host
176
180
    last_checked_ok: datetime.datetime() or None if not yet checked OK
177
181
    timeout:   datetime.timedelta(); How long from last_checked_ok
217
221
    interval = property(lambda self: self._interval,
218
222
                        _set_interval)
219
223
    del _set_interval
220
 
    def __init__(self, name = None, stop_hook=None, config={}):
221
 
        """Note: the 'checker' key in 'config' sets the
222
 
        'checker_command' attribute and *not* the 'checker'
223
 
        attribute."""
 
224
    def __init__(self, name=None, stop_hook=None, fingerprint=None,
 
225
                 secret=None, secfile=None, fqdn=None, timeout=None,
 
226
                 interval=-1, checker=None):
 
227
        """Note: the 'checker' argument sets the 'checker_command'
 
228
        attribute and not the 'checker' attribute.."""
224
229
        self.name = name
225
230
        logger.debug(u"Creating client %r", self.name)
226
 
        # Uppercase and remove spaces from fingerprint for later
227
 
        # comparison purposes with return value from the fingerprint()
228
 
        # function
229
 
        self.fingerprint = config["fingerprint"].upper()\
230
 
                           .replace(u" ", u"")
 
231
        # Uppercase and remove spaces from fingerprint
 
232
        # for later comparison purposes with return value of
 
233
        # the fingerprint() function
 
234
        self.fingerprint = fingerprint.upper().replace(u" ", u"")
231
235
        logger.debug(u"  Fingerprint: %s", self.fingerprint)
232
 
        if "secret" in config:
233
 
            self.secret = config["secret"].decode(u"base64")
234
 
        elif "secfile" in config:
235
 
            sf = open(config["secfile"])
 
236
        if secret:
 
237
            self.secret = secret.decode(u"base64")
 
238
        elif secfile:
 
239
            sf = open(secfile)
236
240
            self.secret = sf.read()
237
241
            sf.close()
238
242
        else:
239
243
            raise TypeError(u"No secret or secfile for client %s"
240
244
                            % self.name)
241
 
        self.host = config.get("host", "")
 
245
        self.fqdn = fqdn
242
246
        self.created = datetime.datetime.now()
243
247
        self.last_checked_ok = None
244
 
        self.timeout = string_to_delta(config["timeout"])
245
 
        self.interval = string_to_delta(config["interval"])
 
248
        self.timeout = string_to_delta(timeout)
 
249
        self.interval = string_to_delta(interval)
246
250
        self.stop_hook = stop_hook
247
251
        self.checker = None
248
252
        self.checker_initiator_tag = None
249
253
        self.stop_initiator_tag = None
250
254
        self.checker_callback_tag = None
251
 
        self.check_command = config["checker"]
 
255
        self.check_command = checker
252
256
    def start(self):
253
257
        """Start this client's checker and timeout hooks"""
254
258
        # Schedule a new checker to be started an 'interval' from now,
267
271
        The possibility that a client might be restarted is left open,
268
272
        but not currently used."""
269
273
        # If this client doesn't have a secret, it is already stopped.
270
 
        if hasattr(self, "secret") and self.secret:
271
 
            logger.info(u"Stopping client %s", self.name)
 
274
        if self.secret:
 
275
            logger.debug(u"Stopping client %s", self.name)
272
276
            self.secret = None
273
277
        else:
274
278
            return False
293
297
        self.checker = None
294
298
        if os.WIFEXITED(condition) \
295
299
               and (os.WEXITSTATUS(condition) == 0):
296
 
            logger.info(u"Checker for %(name)s succeeded",
297
 
                        vars(self))
 
300
            logger.debug(u"Checker for %(name)s succeeded",
 
301
                         vars(self))
298
302
            self.last_checked_ok = now
299
303
            gobject.source_remove(self.stop_initiator_tag)
300
304
            self.stop_initiator_tag = gobject.timeout_add\
304
308
            logger.warning(u"Checker for %(name)s crashed?",
305
309
                           vars(self))
306
310
        else:
307
 
            logger.info(u"Checker for %(name)s failed",
308
 
                        vars(self))
 
311
            logger.debug(u"Checker for %(name)s failed",
 
312
                         vars(self))
309
313
    def start_checker(self):
310
314
        """Start a new checker subprocess if one is not running.
311
315
        If a checker already exists, leave it running and do
321
325
        if self.checker is None:
322
326
            try:
323
327
                # In case check_command has exactly one % operator
324
 
                command = self.check_command % self.host
 
328
                command = self.check_command % self.fqdn
325
329
            except TypeError:
326
330
                # Escape attributes for the shell
327
331
                escaped_attrs = dict((key, re.escape(str(val)))
334
338
                                 u' %s', self.check_command, error)
335
339
                    return True # Try again later
336
340
            try:
337
 
                logger.info(u"Starting checker %r for %s",
338
 
                            command, self.name)
 
341
                logger.debug(u"Starting checker %r for %s",
 
342
                             command, self.name)
339
343
                self.checker = subprocess.Popen(command,
340
344
                                                close_fds=True,
341
345
                                                shell=True, cwd="/")
354
358
            self.checker_callback_tag = None
355
359
        if getattr(self, "checker", None) is None:
356
360
            return
357
 
        logger.debug(u"Stopping checker for %(name)s", vars(self))
 
361
        logger.debug("Stopping checker for %(name)s", vars(self))
358
362
        try:
359
363
            os.kill(self.checker.pid, signal.SIGTERM)
360
364
            #os.sleep(0.5)
392
396
 
393
397
def fingerprint(openpgp):
394
398
    "Convert an OpenPGP bytestring to a hexdigit fingerprint string"
 
399
    # New empty GnuTLS certificate
 
400
    crt = gnutls.library.types.gnutls_openpgp_crt_t()
 
401
    gnutls.library.functions.gnutls_openpgp_crt_init\
 
402
        (ctypes.byref(crt))
395
403
    # New GnuTLS "datum" with the OpenPGP public key
396
404
    datum = gnutls.library.types.gnutls_datum_t\
397
405
        (ctypes.cast(ctypes.c_char_p(openpgp),
398
406
                     ctypes.POINTER(ctypes.c_ubyte)),
399
407
         ctypes.c_uint(len(openpgp)))
400
 
    # New empty GnuTLS certificate
401
 
    crt = gnutls.library.types.gnutls_openpgp_crt_t()
402
 
    gnutls.library.functions.gnutls_openpgp_crt_init\
403
 
        (ctypes.byref(crt))
404
408
    # Import the OpenPGP public key into the certificate
405
 
    gnutls.library.functions.gnutls_openpgp_crt_import\
406
 
                    (crt, ctypes.byref(datum),
407
 
                     gnutls.library.constants.GNUTLS_OPENPGP_FMT_RAW)
 
409
    ret = gnutls.library.functions.gnutls_openpgp_crt_import\
 
410
        (crt,
 
411
         ctypes.byref(datum),
 
412
         gnutls.library.constants.GNUTLS_OPENPGP_FMT_RAW)
408
413
    # New buffer for the fingerprint
409
414
    buffer = ctypes.create_string_buffer(20)
410
415
    buffer_length = ctypes.c_size_t()
426
431
    Note: This will run in its own forked process."""
427
432
    
428
433
    def handle(self):
429
 
        logger.info(u"TCP connection from: %s",
 
434
        logger.debug(u"TCP connection from: %s",
430
435
                     unicode(self.client_address))
431
436
        session = gnutls.connection.ClientSession\
432
437
                  (self.request, gnutls.connection.X509Credentials())
458
463
        try:
459
464
            session.handshake()
460
465
        except gnutls.errors.GNUTLSError, error:
461
 
            logger.warning(u"Handshake failed: %s", error)
 
466
            logger.debug(u"Handshake failed: %s", error)
462
467
            # Do not run session.bye() here: the session is not
463
468
            # established.  Just abandon the request.
464
469
            return
465
470
        try:
466
471
            fpr = fingerprint(peer_certificate(session))
467
472
        except (TypeError, gnutls.errors.GNUTLSError), error:
468
 
            logger.warning(u"Bad certificate: %s", error)
 
473
            logger.debug(u"Bad certificate: %s", error)
469
474
            session.bye()
470
475
            return
471
476
        logger.debug(u"Fingerprint: %s", fpr)
475
480
                client = c
476
481
                break
477
482
        if not client:
478
 
            logger.warning(u"Client not found for fingerprint: %s",
479
 
                           fpr)
 
483
            logger.debug(u"Client not found for fingerprint: %s", fpr)
480
484
            session.bye()
481
485
            return
482
486
        # Have to check if client.still_valid(), since it is possible
483
487
        # that the client timed out while establishing the GnuTLS
484
488
        # session.
485
489
        if not client.still_valid():
486
 
            logger.warning(u"Client %(name)s is invalid",
487
 
                           vars(client))
 
490
            logger.debug(u"Client %(name)s is invalid", vars(client))
488
491
            session.bye()
489
492
            return
490
493
        sent_size = 0
525
528
                                       self.settings["interface"])
526
529
            except socket.error, error:
527
530
                if error[0] == errno.EPERM:
528
 
                    logger.error(u"No permission to"
529
 
                                 u" bind to interface %s",
530
 
                                 self.settings["interface"])
 
531
                    logger.warning(u"No permission to"
 
532
                                   u" bind to interface %s",
 
533
                                   self.settings["interface"])
531
534
                else:
532
535
                    raise error
533
536
        # Only bind(2) the socket if we really need to.
536
539
                in6addr_any = "::"
537
540
                self.server_address = (in6addr_any,
538
541
                                       self.server_address[1])
539
 
            elif not self.server_address[1]:
 
542
            elif self.server_address[1] is None:
540
543
                self.server_address = (self.server_address[0],
541
544
                                       0)
542
 
#                 if self.settings["interface"]:
543
 
#                     self.server_address = (self.server_address[0],
544
 
#                                            0, # port
545
 
#                                            0, # flowinfo
546
 
#                                            if_nametoindex
547
 
#                                            (self.settings
548
 
#                                             ["interface"]))
549
545
            return super(type(self), self).server_bind()
550
546
 
551
547
 
586
582
def server_state_changed(state):
587
583
    """Derived from the Avahi example code"""
588
584
    if state == avahi.SERVER_COLLISION:
589
 
        logger.error(u"Server name collision")
 
585
        logger.warning(u"Server name collision")
590
586
        service.remove()
591
587
    elif state == avahi.SERVER_RUNNING:
592
588
        service.add()
631
627
    return if_nametoindex(interface)
632
628
 
633
629
 
634
 
def daemon(nochdir = False, noclose = False):
 
630
def daemon(nochdir, noclose):
635
631
    """See daemon(3).  Standard BSD Unix function.
636
632
    This should really exist as os.daemon, but it doesn't (yet)."""
637
633
    if os.fork():
639
635
    os.setsid()
640
636
    if not nochdir:
641
637
        os.chdir("/")
642
 
    if os.fork():
643
 
        sys.exit()
644
638
    if not noclose:
645
639
        # Close all standard open file descriptors
646
640
        null = os.open(os.path.devnull, os.O_NOCTTY | os.O_RDWR)
658
652
    global main_loop_started
659
653
    main_loop_started = False
660
654
    
661
 
    parser = OptionParser(version = "%%prog %s" % version)
 
655
    parser = OptionParser()
662
656
    parser.add_option("-i", "--interface", type="string",
663
657
                      metavar="IF", help="Bind to interface IF")
664
658
    parser.add_option("-a", "--address", type="string",
667
661
                      help="Port number to receive requests on")
668
662
    parser.add_option("--check", action="store_true", default=False,
669
663
                      help="Run self-test")
670
 
    parser.add_option("--debug", action="store_true",
 
664
    parser.add_option("--debug", action="store_true", default=False,
671
665
                      help="Debug mode; run in foreground and log to"
672
666
                      " terminal")
673
667
    parser.add_option("--priority", type="string", help="GnuTLS"
698
692
    # Parse config file for server-global settings
699
693
    server_config = ConfigParser.SafeConfigParser(server_defaults)
700
694
    del server_defaults
701
 
    server_config.read(os.path.join(options.configdir, "mandos.conf"))
 
695
    server_config.read(os.path.join(options.configdir, "server.conf"))
702
696
    server_section = "server"
703
697
    # Convert the SafeConfigParser object to a dict
704
698
    server_settings = dict(server_config.items(server_section))
717
711
    del options
718
712
    # Now we have our good server settings in "server_settings"
719
713
    
720
 
    debug = server_settings["debug"]
721
 
    
722
 
    if not debug:
723
 
        syslogger.setLevel(logging.WARNING)
724
 
        console.setLevel(logging.WARNING)
725
 
    
726
 
    if server_settings["servicename"] != "Mandos":
727
 
        syslogger.setFormatter(logging.Formatter\
728
 
                               ('Mandos (%s): %%(levelname)s:'
729
 
                                ' %%(message)s'
730
 
                                % server_settings["servicename"]))
731
 
    
732
714
    # Parse config file with clients
733
715
    client_defaults = { "timeout": "1h",
734
716
                        "interval": "5m",
735
 
                        "checker": "fping -q -- %%(host)s",
 
717
                        "checker": "fping -q -- %%(fqdn)s",
736
718
                        }
737
719
    client_config = ConfigParser.SafeConfigParser(client_defaults)
738
720
    client_config.read(os.path.join(server_settings["configdir"],
756
738
            avahi.DBUS_INTERFACE_SERVER )
757
739
    # End of Avahi example code
758
740
    
 
741
    debug = server_settings["debug"]
 
742
    
 
743
    if debug:
 
744
        console = logging.StreamHandler()
 
745
        # console.setLevel(logging.DEBUG)
 
746
        console.setFormatter(logging.Formatter\
 
747
                             ('%(levelname)s: %(message)s'))
 
748
        logger.addHandler(console)
 
749
        del console
 
750
    
759
751
    clients = Set()
760
752
    def remove_from_clients(client):
761
753
        clients.remove(client)
762
754
        if not clients:
763
 
            logger.critical(u"No clients left, exiting")
 
755
            logger.debug(u"No clients left, exiting")
764
756
            sys.exit()
765
757
    
766
 
    clients.update(Set(Client(name = section,
 
758
    clients.update(Set(Client(name=section,
767
759
                              stop_hook = remove_from_clients,
768
 
                              config
769
 
                              = dict(client_config.items(section)))
 
760
                              **(dict(client_config\
 
761
                                      .items(section))))
770
762
                       for section in client_config.sections()))
771
 
    if not clients:
772
 
        logger.critical(u"No clients defined")
773
 
        sys.exit(1)
774
763
    
775
764
    if not debug:
776
 
        logger.removeHandler(console)
777
 
        daemon()
778
 
    
779
 
    pidfilename = "/var/run/mandos/mandos.pid"
780
 
    pid = os.getpid()
781
 
    try:
782
 
        pidfile = open(pidfilename, "w")
783
 
        pidfile.write(str(pid) + "\n")
784
 
        pidfile.close()
785
 
        del pidfile
786
 
    except IOError, err:
787
 
        logger.error(u"Could not write %s file with PID %d",
788
 
                     pidfilename, os.getpid())
 
765
        daemon(False, False)
789
766
    
790
767
    def cleanup():
791
768
        "Cleanup function; run on exit"
818
795
                                clients=clients)
819
796
    # Find out what port we got
820
797
    service.port = tcp_server.socket.getsockname()[1]
821
 
    logger.info(u"Now listening on address %r, port %d, flowinfo %d,"
822
 
                u" scope_id %d" % tcp_server.socket.getsockname())
 
798
    logger.debug(u"Now listening on address %r, port %d, flowinfo %d,"
 
799
                 u" scope_id %d" % tcp_server.socket.getsockname())
823
800
    
824
801
    #service.interface = tcp_server.socket.getsockname()[3]
825
802
    
838
815
                             tcp_server.handle_request\
839
816
                             (*args[2:], **kwargs) or True)
840
817
        
841
 
        logger.debug(u"Starting main loop")
 
818
        logger.debug("Starting main loop")
842
819
        main_loop_started = True
843
820
        main_loop.run()
844
821
    except AvahiError, error: