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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
14
# Copyright © 2007-2008 Teddy Hogeborn & Björn Påhlsson
61
61
from dbus.mainloop.glib import DBusGMainLoop
62
62
import ctypes
63
63
 
 
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
 
64
75
 
65
76
logger = logging.Logger('mandos')
66
77
syslogger = logging.handlers.SysLogHandler\
85
96
 
86
97
 
87
98
class AvahiService(object):
88
 
    """An Avahi (Zeroconf) service.
89
 
    Attributes:
 
99
    """
90
100
    interface: integer; avahi.IF_UNSPEC or an interface index.
91
101
               Used to optionally bind to the specified interface.
92
 
    name: string; Example: 'Mandos'
93
 
    type: string; Example: '_mandos._tcp'.
94
 
                  See <http://www.dns-sd.org/ServiceTypes.html>
95
 
    port: integer; what port to announce
96
 
    TXT: list of strings; TXT record for the service
97
 
    domain: string; Domain to publish on, default to .local if empty.
98
 
    host: string; Host to publish records for, default is localhost
99
 
    max_renames: integer; maximum number of renames
100
 
    rename_count: integer; counter so we only rename after collisions
101
 
                  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
102
113
    """
103
114
    def __init__(self, interface = avahi.IF_UNSPEC, name = None,
104
115
                 type = None, port = None, TXT = None, domain = "",
105
116
                 host = "", max_renames = 12):
 
117
        """An Avahi (Zeroconf) service. """
106
118
        self.interface = interface
107
119
        self.name = name
108
120
        self.type = type
121
133
                            u" retries, exiting.", rename_count)
122
134
            raise AvahiServiceError("Too many renames")
123
135
        name = server.GetAlternativeServiceName(name)
124
 
        logger.error(u"Changing name to %r ...", name)
 
136
        logger.notice(u"Changing name to %r ...", name)
125
137
        self.remove()
126
138
        self.add()
127
139
        self.rename_count += 1
209
221
    interval = property(lambda self: self._interval,
210
222
                        _set_interval)
211
223
    del _set_interval
212
 
    def __init__(self, name = None, stop_hook=None, config={}):
213
 
        """Note: the 'checker' key in 'config' sets the
214
 
        'checker_command' attribute and *not* the 'checker'
215
 
        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.."""
216
229
        self.name = name
217
230
        logger.debug(u"Creating client %r", self.name)
218
 
        # Uppercase and remove spaces from fingerprint for later
219
 
        # comparison purposes with return value from the fingerprint()
220
 
        # function
221
 
        self.fingerprint = config["fingerprint"].upper()\
222
 
                           .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"")
223
235
        logger.debug(u"  Fingerprint: %s", self.fingerprint)
224
 
        if "secret" in config:
225
 
            self.secret = config["secret"].decode(u"base64")
226
 
        elif "secfile" in config:
227
 
            sf = open(config["secfile"])
 
236
        if secret:
 
237
            self.secret = secret.decode(u"base64")
 
238
        elif secfile:
 
239
            sf = open(secfile)
228
240
            self.secret = sf.read()
229
241
            sf.close()
230
242
        else:
231
243
            raise TypeError(u"No secret or secfile for client %s"
232
244
                            % self.name)
233
 
        self.fqdn = config.get("fqdn", "")
 
245
        self.fqdn = fqdn
234
246
        self.created = datetime.datetime.now()
235
247
        self.last_checked_ok = None
236
 
        self.timeout = string_to_delta(config["timeout"])
237
 
        self.interval = string_to_delta(config["interval"])
 
248
        self.timeout = string_to_delta(timeout)
 
249
        self.interval = string_to_delta(interval)
238
250
        self.stop_hook = stop_hook
239
251
        self.checker = None
240
252
        self.checker_initiator_tag = None
241
253
        self.stop_initiator_tag = None
242
254
        self.checker_callback_tag = None
243
 
        self.check_command = config["checker"]
 
255
        self.check_command = checker
244
256
    def start(self):
245
257
        """Start this client's checker and timeout hooks"""
246
258
        # Schedule a new checker to be started an 'interval' from now,
260
272
        but not currently used."""
261
273
        # If this client doesn't have a secret, it is already stopped.
262
274
        if self.secret:
263
 
            logger.info(u"Stopping client %s", self.name)
 
275
            logger.debug(u"Stopping client %s", self.name)
264
276
            self.secret = None
265
277
        else:
266
278
            return False
285
297
        self.checker = None
286
298
        if os.WIFEXITED(condition) \
287
299
               and (os.WEXITSTATUS(condition) == 0):
288
 
            logger.info(u"Checker for %(name)s succeeded",
289
 
                        vars(self))
 
300
            logger.debug(u"Checker for %(name)s succeeded",
 
301
                         vars(self))
290
302
            self.last_checked_ok = now
291
303
            gobject.source_remove(self.stop_initiator_tag)
292
304
            self.stop_initiator_tag = gobject.timeout_add\
296
308
            logger.warning(u"Checker for %(name)s crashed?",
297
309
                           vars(self))
298
310
        else:
299
 
            logger.info(u"Checker for %(name)s failed",
300
 
                        vars(self))
 
311
            logger.debug(u"Checker for %(name)s failed",
 
312
                         vars(self))
301
313
    def start_checker(self):
302
314
        """Start a new checker subprocess if one is not running.
303
315
        If a checker already exists, leave it running and do
326
338
                                 u' %s', self.check_command, error)
327
339
                    return True # Try again later
328
340
            try:
329
 
                logger.info(u"Starting checker %r for %s",
330
 
                            command, self.name)
 
341
                logger.debug(u"Starting checker %r for %s",
 
342
                             command, self.name)
331
343
                self.checker = subprocess.Popen(command,
332
344
                                                close_fds=True,
333
345
                                                shell=True, cwd="/")
384
396
 
385
397
def fingerprint(openpgp):
386
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))
387
403
    # New GnuTLS "datum" with the OpenPGP public key
388
404
    datum = gnutls.library.types.gnutls_datum_t\
389
405
        (ctypes.cast(ctypes.c_char_p(openpgp),
390
406
                     ctypes.POINTER(ctypes.c_ubyte)),
391
407
         ctypes.c_uint(len(openpgp)))
392
 
    # New empty GnuTLS certificate
393
 
    crt = gnutls.library.types.gnutls_openpgp_crt_t()
394
 
    gnutls.library.functions.gnutls_openpgp_crt_init\
395
 
        (ctypes.byref(crt))
396
408
    # Import the OpenPGP public key into the certificate
397
 
    gnutls.library.functions.gnutls_openpgp_crt_import\
398
 
                    (crt, ctypes.byref(datum),
399
 
                     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)
400
413
    # New buffer for the fingerprint
401
414
    buffer = ctypes.create_string_buffer(20)
402
415
    buffer_length = ctypes.c_size_t()
418
431
    Note: This will run in its own forked process."""
419
432
    
420
433
    def handle(self):
421
 
        logger.info(u"TCP connection from: %s",
 
434
        logger.debug(u"TCP connection from: %s",
422
435
                     unicode(self.client_address))
423
436
        session = gnutls.connection.ClientSession\
424
437
                  (self.request, gnutls.connection.X509Credentials())
425
 
        
426
 
        line = self.request.makefile().readline()
427
 
        logger.debug(u"Protocol version: %r", line)
428
 
        try:
429
 
            if int(line.strip().split()[0]) > 1:
430
 
                raise RuntimeError
431
 
        except (ValueError, IndexError, RuntimeError), error:
432
 
            logger.error(u"Unknown protocol version: %s", error)
433
 
            return
434
 
        
435
438
        # Note: gnutls.connection.X509Credentials is really a generic
436
439
        # GnuTLS certificate credentials object so long as no X.509
437
440
        # keys are added to it.  Therefore, we can use it here despite
450
453
        try:
451
454
            session.handshake()
452
455
        except gnutls.errors.GNUTLSError, error:
453
 
            logger.warning(u"Handshake failed: %s", error)
 
456
            logger.debug(u"Handshake failed: %s", error)
454
457
            # Do not run session.bye() here: the session is not
455
458
            # established.  Just abandon the request.
456
459
            return
457
460
        try:
458
461
            fpr = fingerprint(peer_certificate(session))
459
462
        except (TypeError, gnutls.errors.GNUTLSError), error:
460
 
            logger.warning(u"Bad certificate: %s", error)
 
463
            logger.debug(u"Bad certificate: %s", error)
461
464
            session.bye()
462
465
            return
463
466
        logger.debug(u"Fingerprint: %s", fpr)
467
470
                client = c
468
471
                break
469
472
        if not client:
470
 
            logger.warning(u"Client not found for fingerprint: %s",
471
 
                           fpr)
 
473
            logger.debug(u"Client not found for fingerprint: %s", fpr)
472
474
            session.bye()
473
475
            return
474
476
        # Have to check if client.still_valid(), since it is possible
475
477
        # that the client timed out while establishing the GnuTLS
476
478
        # session.
477
479
        if not client.still_valid():
478
 
            logger.warning(u"Client %(name)s is invalid",
479
 
                           vars(client))
 
480
            logger.debug(u"Client %(name)s is invalid", vars(client))
480
481
            session.bye()
481
482
            return
482
483
        sent_size = 0
517
518
                                       self.settings["interface"])
518
519
            except socket.error, error:
519
520
                if error[0] == errno.EPERM:
520
 
                    logger.error(u"No permission to"
521
 
                                 u" bind to interface %s",
522
 
                                 self.settings["interface"])
 
521
                    logger.warning(u"No permission to"
 
522
                                   u" bind to interface %s",
 
523
                                   self.settings["interface"])
523
524
                else:
524
525
                    raise error
525
526
        # Only bind(2) the socket if we really need to.
528
529
                in6addr_any = "::"
529
530
                self.server_address = (in6addr_any,
530
531
                                       self.server_address[1])
531
 
            elif not self.server_address[1]:
 
532
            elif self.server_address[1] is None:
532
533
                self.server_address = (self.server_address[0],
533
534
                                       0)
534
 
#                 if self.settings["interface"]:
535
 
#                     self.server_address = (self.server_address[0],
536
 
#                                            0, # port
537
 
#                                            0, # flowinfo
538
 
#                                            if_nametoindex
539
 
#                                            (self.settings
540
 
#                                             ["interface"]))
541
535
            return super(type(self), self).server_bind()
542
536
 
543
537
 
578
572
def server_state_changed(state):
579
573
    """Derived from the Avahi example code"""
580
574
    if state == avahi.SERVER_COLLISION:
581
 
        logger.error(u"Server name collision")
 
575
        logger.warning(u"Server name collision")
582
576
        service.remove()
583
577
    elif state == avahi.SERVER_RUNNING:
584
578
        service.add()
598
592
                        unicode(error))
599
593
        raise AvahiGroupError("State changed: %s", str(error))
600
594
 
601
 
def if_nametoindex(interface):
 
595
def if_nametoindex(interface, _func=[None]):
602
596
    """Call the C function if_nametoindex(), or equivalent"""
603
 
    global if_nametoindex
 
597
    if _func[0] is not None:
 
598
        return _func[0](interface)
604
599
    try:
605
600
        if "ctypes.util" not in sys.modules:
606
601
            import ctypes.util
607
 
        if_nametoindex = ctypes.cdll.LoadLibrary\
608
 
            (ctypes.util.find_library("c")).if_nametoindex
 
602
        while True:
 
603
            try:
 
604
                libc = ctypes.cdll.LoadLibrary\
 
605
                       (ctypes.util.find_library("c"))
 
606
                _func[0] = libc.if_nametoindex
 
607
                return _func[0](interface)
 
608
            except IOError, e:
 
609
                if e != errno.EINTR:
 
610
                    raise
609
611
    except (OSError, AttributeError):
610
612
        if "struct" not in sys.modules:
611
613
            import struct
612
614
        if "fcntl" not in sys.modules:
613
615
            import fcntl
614
 
        def if_nametoindex(interface):
 
616
        def the_hard_way(interface):
615
617
            "Get an interface index the hard way, i.e. using fcntl()"
616
618
            SIOCGIFINDEX = 0x8933  # From /usr/include/linux/sockios.h
617
619
            s = socket.socket()
620
622
            s.close()
621
623
            interface_index = struct.unpack("I", ifreq[16:20])[0]
622
624
            return interface_index
623
 
    return if_nametoindex(interface)
624
 
 
625
 
 
626
 
def daemon(nochdir = False, noclose = False):
 
625
        _func[0] = the_hard_way
 
626
        return _func[0](interface)
 
627
 
 
628
 
 
629
def daemon(nochdir, noclose):
627
630
    """See daemon(3).  Standard BSD Unix function.
628
631
    This should really exist as os.daemon, but it doesn't (yet)."""
629
632
    if os.fork():
631
634
    os.setsid()
632
635
    if not nochdir:
633
636
        os.chdir("/")
634
 
    if os.fork():
635
 
        sys.exit()
636
637
    if not noclose:
637
638
        # Close all standard open file descriptors
638
639
        null = os.open(os.path.devnull, os.O_NOCTTY | os.O_RDWR)
659
660
                      help="Port number to receive requests on")
660
661
    parser.add_option("--check", action="store_true", default=False,
661
662
                      help="Run self-test")
662
 
    parser.add_option("--debug", action="store_true",
 
663
    parser.add_option("--debug", action="store_true", default=False,
663
664
                      help="Debug mode; run in foreground and log to"
664
665
                      " terminal")
665
666
    parser.add_option("--priority", type="string", help="GnuTLS"
690
691
    # Parse config file for server-global settings
691
692
    server_config = ConfigParser.SafeConfigParser(server_defaults)
692
693
    del server_defaults
693
 
    server_config.read(os.path.join(options.configdir, "mandos.conf"))
 
694
    server_config.read(os.path.join(options.configdir, "server.conf"))
694
695
    server_section = "server"
695
696
    # Convert the SafeConfigParser object to a dict
696
697
    server_settings = dict(server_config.items(server_section))
750
751
    def remove_from_clients(client):
751
752
        clients.remove(client)
752
753
        if not clients:
753
 
            logger.critical(u"No clients left, exiting")
 
754
            logger.debug(u"No clients left, exiting")
754
755
            sys.exit()
755
756
    
756
 
    clients.update(Set(Client(name = section,
 
757
    clients.update(Set(Client(name=section,
757
758
                              stop_hook = remove_from_clients,
758
 
                              config
759
 
                              = dict(client_config.items(section)))
 
759
                              **(dict(client_config\
 
760
                                      .items(section))))
760
761
                       for section in client_config.sections()))
761
762
    
762
763
    if not debug:
763
 
        daemon()
 
764
        daemon(False, False)
764
765
    
765
766
    def cleanup():
766
767
        "Cleanup function; run on exit"
793
794
                                clients=clients)
794
795
    # Find out what port we got
795
796
    service.port = tcp_server.socket.getsockname()[1]
796
 
    logger.info(u"Now listening on address %r, port %d, flowinfo %d,"
797
 
                u" scope_id %d" % tcp_server.socket.getsockname())
 
797
    logger.debug(u"Now listening on address %r, port %d, flowinfo %d,"
 
798
                 u" scope_id %d" % tcp_server.socket.getsockname())
798
799
    
799
800
    #service.interface = tcp_server.socket.getsockname()[3]
800
801