41
9
import gnutls.crypto
42
10
import gnutls.connection
43
11
import gnutls.errors
44
import gnutls.library.functions
45
import gnutls.library.constants
46
import gnutls.library.types
47
12
import ConfigParser
57
import logging.handlers
62
from dbus.mainloop.glib import DBusGMainLoop
65
# Brief description of the operation of this program:
67
# This server announces itself as a Zeroconf service. Connecting
68
# clients use the TLS protocol, with the unusual quirk that this
69
# server program acts as a TLS "client" while the connecting clients
70
# acts as a TLS "server". The clients (acting as a TLS "server") must
71
# supply an OpenPGP certificate, and the fingerprint of this
72
# certificate is used by this server to look up (in a list read from a
73
# file at start time) which binary blob to give the client. No other
74
# authentication or authorization is done by this server.
77
logger = logging.Logger('mandos')
78
syslogger = logging.handlers.SysLogHandler\
79
(facility = logging.handlers.SysLogHandler.LOG_DAEMON)
80
syslogger.setFormatter(logging.Formatter\
81
('%(levelname)s: %(message)s'))
82
logger.addHandler(syslogger)
85
# This variable is used to optionally bind to a specified interface.
86
# It is a global variable to fit in with the other variables from the
88
serviceInterface = avahi.IF_UNSPEC
89
# From the Avahi example code:
91
serviceType = "_mandos._tcp" # http://www.dns-sd.org/ServiceTypes.html
92
servicePort = None # Not known at startup
93
serviceTXT = [] # TXT record for the service
94
domain = "" # Domain to publish on, default to .local
95
host = "" # Host to publish records for, default to localhost
96
group = None #our entry group
97
rename_count = 12 # Counter so we only rename after collisions a
98
# sensible number of times
99
# End of Avahi example code
102
15
class Client(object):
103
"""A representation of a client host served by this server.
105
name: string; from the config file, used in log messages
106
fingerprint: string (40 or 32 hexadecimal digits); used to
107
uniquely identify the client
108
secret: bytestring; sent verbatim (over TLS) to client
109
fqdn: string (FQDN); available for use by the checker command
110
created: datetime.datetime()
111
last_seen: datetime.datetime() or None if not yet seen
112
timeout: datetime.timedelta(); How long from last_seen until
113
this client is invalid
114
interval: datetime.timedelta(); How often to start a new checker
115
stop_hook: If set, called by stop() as stop_hook(self)
116
checker: subprocess.Popen(); a running checker process used
117
to see if the client lives.
118
Is None if no process is running.
119
checker_initiator_tag: a gobject event source tag, or None
120
stop_initiator_tag: - '' -
121
checker_callback_tag: - '' -
122
checker_command: string; External command which is run to check if
123
client lives. %()s expansions are done at
124
runtime with vars(self) as dict, so that for
125
instance %(name)s can be used in the command.
127
_timeout: Real variable for 'timeout'
128
_interval: Real variable for 'interval'
129
_timeout_milliseconds: Used by gobject.timeout_add()
130
_interval_milliseconds: - '' -
132
def _set_timeout(self, timeout):
133
"Setter function for 'timeout' attribute"
134
self._timeout = timeout
135
self._timeout_milliseconds = ((self.timeout.days
136
* 24 * 60 * 60 * 1000)
137
+ (self.timeout.seconds * 1000)
138
+ (self.timeout.microseconds
140
timeout = property(lambda self: self._timeout,
143
def _set_interval(self, interval):
144
"Setter function for 'interval' attribute"
145
self._interval = interval
146
self._interval_milliseconds = ((self.interval.days
147
* 24 * 60 * 60 * 1000)
148
+ (self.interval.seconds
150
+ (self.interval.microseconds
152
interval = property(lambda self: self._interval,
155
def __init__(self, name=None, stop_hook=None, fingerprint=None,
156
secret=None, secfile=None, fqdn=None, timeout=None,
157
interval=-1, checker=None):
158
"""Note: the 'checker' argument sets the 'checker_command'
159
attribute and not the 'checker' attribute.."""
16
def __init__(self, name=None, dn=None, password=None,
17
passfile=None, fqdn=None, timeout=None,
161
logger.debug(u"Creating client %r", self.name)
162
# Uppercase and remove spaces from fingerprint
163
# for later comparison purposes with return value of
164
# the fingerprint() function
165
self.fingerprint = fingerprint.upper().replace(u" ", u"")
166
logger.debug(u" Fingerprint: %s", self.fingerprint)
168
self.secret = secret.decode(u"base64")
171
self.secret = sf.read()
22
self.password = password
24
self.password = open(passfile).readall()
174
raise RuntimeError(u"No secret or secfile for client %s"
176
self.fqdn = fqdn # string
26
print "No Password or Passfile in client config file"
27
# raise RuntimeError XXX
28
self.password = "gazonk"
177
30
self.created = datetime.datetime.now()
178
31
self.last_seen = None
179
self.timeout = string_to_delta(timeout)
180
self.interval = string_to_delta(interval)
181
self.stop_hook = stop_hook
183
self.checker_initiator_tag = None
184
self.stop_initiator_tag = None
185
self.checker_callback_tag = None
186
self.check_command = checker
188
"""Start this client's checker and timeout hooks"""
189
# Schedule a new checker to be started an 'interval' from now,
190
# and every interval from then on.
191
self.checker_initiator_tag = gobject.timeout_add\
192
(self._interval_milliseconds,
194
# Also start a new checker *right now*.
196
# Schedule a stop() when 'timeout' has passed
197
self.stop_initiator_tag = gobject.timeout_add\
198
(self._timeout_milliseconds,
202
The possibility that this client might be restarted is left
203
open, but not currently used."""
204
# If this client doesn't have a secret, it is already stopped.
206
logger.debug(u"Stopping client %s", self.name)
210
if hasattr(self, "stop_initiator_tag") \
211
and self.stop_initiator_tag:
212
gobject.source_remove(self.stop_initiator_tag)
213
self.stop_initiator_tag = None
214
if hasattr(self, "checker_initiator_tag") \
215
and self.checker_initiator_tag:
216
gobject.source_remove(self.checker_initiator_tag)
217
self.checker_initiator_tag = None
221
# Do not run this again if called by a gobject.timeout_add
224
self.stop_hook = None
226
def checker_callback(self, pid, condition):
227
"""The checker has completed, so take appropriate actions."""
228
now = datetime.datetime.now()
229
self.checker_callback_tag = None
231
if os.WIFEXITED(condition) \
232
and (os.WEXITSTATUS(condition) == 0):
233
logger.debug(u"Checker for %(name)s succeeded",
236
gobject.source_remove(self.stop_initiator_tag)
237
self.stop_initiator_tag = gobject.timeout_add\
238
(self._timeout_milliseconds,
240
elif not os.WIFEXITED(condition):
241
logger.warning(u"Checker for %(name)s crashed?",
244
logger.debug(u"Checker for %(name)s failed",
246
def start_checker(self):
247
"""Start a new checker subprocess if one is not running.
248
If a checker already exists, leave it running and do
250
# The reason for not killing a running checker is that if we
251
# did that, then if a checker (for some reason) started
252
# running slowly and taking more than 'interval' time, the
253
# client would inevitably timeout, since no checker would get
254
# a chance to run to completion. If we instead leave running
255
# checkers alone, the checker would have to take more time
256
# than 'timeout' for the client to be declared invalid, which
257
# is as it should be.
258
if self.checker is None:
260
command = self.check_command % self.fqdn
262
escaped_attrs = dict((key, re.escape(str(val)))
264
vars(self).iteritems())
266
command = self.check_command % escaped_attrs
267
except TypeError, error:
268
logger.critical(u'Could not format string "%s":'
269
u' %s', self.check_command, error)
270
return True # Try again later
272
logger.debug(u"Starting checker %r for %s",
274
self.checker = subprocess.\
276
close_fds=True, shell=True,
278
self.checker_callback_tag = gobject.child_watch_add\
280
self.checker_callback)
281
except subprocess.OSError, error:
282
logger.error(u"Failed to start subprocess: %s",
284
# Re-run this periodically if run by gobject.timeout_add
286
def stop_checker(self):
287
"""Force the checker process, if any, to stop."""
288
if self.checker_callback_tag:
289
gobject.source_remove(self.checker_callback_tag)
290
self.checker_callback_tag = None
291
if not hasattr(self, "checker") or self.checker is None:
293
logger.debug("Stopping checker for %(name)s", vars(self))
33
timeout = self.server.options.timeout
34
self.timeout = timeout
36
interval = self.server.options.interval
37
self.interval = interval
38
self.next_check = datetime.datetime.now()
40
def server_bind(self):
41
if self.options.interface:
42
if not hasattr(socket, "SO_BINDTODEVICE"):
43
# From /usr/include/asm-i486/socket.h
44
socket.SO_BINDTODEVICE = 25
295
os.kill(self.checker.pid, signal.SIGTERM)
297
#if self.checker.poll() is None:
298
# os.kill(self.checker.pid, signal.SIGKILL)
299
except OSError, error:
300
if error.errno != errno.ESRCH:
303
def still_valid(self, now=None):
304
"""Has the timeout not yet passed for this client?"""
306
now = datetime.datetime.now()
307
if self.last_seen is None:
308
return now < (self.created + self.timeout)
310
return now < (self.last_seen + self.timeout)
313
def peer_certificate(session):
314
"Return the peer's OpenPGP certificate as a bytestring"
315
# If not an OpenPGP certificate...
316
if gnutls.library.functions.gnutls_certificate_type_get\
317
(session._c_object) \
318
!= gnutls.library.constants.GNUTLS_CRT_OPENPGP:
319
# ...do the normal thing
320
return session.peer_certificate
321
list_size = ctypes.c_uint()
322
cert_list = gnutls.library.functions.gnutls_certificate_get_peers\
323
(session._c_object, ctypes.byref(list_size))
324
if list_size.value == 0:
327
return ctypes.string_at(cert.data, cert.size)
330
def fingerprint(openpgp):
331
"Convert an OpenPGP bytestring to a hexdigit fingerprint string"
332
# New empty GnuTLS certificate
333
crt = gnutls.library.types.gnutls_openpgp_crt_t()
334
gnutls.library.functions.gnutls_openpgp_crt_init\
336
# New GnuTLS "datum" with the OpenPGP public key
337
datum = gnutls.library.types.gnutls_datum_t\
338
(ctypes.cast(ctypes.c_char_p(openpgp),
339
ctypes.POINTER(ctypes.c_ubyte)),
340
ctypes.c_uint(len(openpgp)))
341
# Import the OpenPGP public key into the certificate
342
ret = gnutls.library.functions.gnutls_openpgp_crt_import\
345
gnutls.library.constants.GNUTLS_OPENPGP_FMT_RAW)
346
# New buffer for the fingerprint
347
buffer = ctypes.create_string_buffer(20)
348
buffer_length = ctypes.c_size_t()
349
# Get the fingerprint from the certificate into the buffer
350
gnutls.library.functions.gnutls_openpgp_crt_get_fingerprint\
351
(crt, ctypes.byref(buffer), ctypes.byref(buffer_length))
352
# Deinit the certificate
353
gnutls.library.functions.gnutls_openpgp_crt_deinit(crt)
354
# Convert the buffer to a Python bytestring
355
fpr = ctypes.string_at(buffer, buffer_length.value)
356
# Convert the bytestring to hexadecimal notation
357
hex_fpr = u''.join(u"%02X" % ord(char) for char in fpr)
46
self.socket.setsockopt(socket.SOL_SOCKET,
47
socket.SO_BINDTODEVICE,
48
self.options.interface)
49
except socket.error, error:
50
if error[0] == errno.EPERM:
51
print "Warning: Denied permission to bind to interface", \
52
self.options.interface
55
return super(type(self), self).server_bind()
58
def init_with_options(self, *args, **kwargs):
59
if "options" in kwargs:
60
self.options = kwargs["options"]
62
if "clients" in kwargs:
63
self.clients = kwargs["clients"]
65
if "credentials" in kwargs:
66
self.credentials = kwargs["credentials"]
67
del kwargs["credentials"]
68
return super(type(self), self).__init__(*args, **kwargs)
71
class udp_handler(SocketServer.DatagramRequestHandler, object):
73
self.wfile.write("Polo")
74
print "UDP request answered"
77
class IPv6_UDPServer(SocketServer.UDPServer, object):
78
__init__ = init_with_options
79
address_family = socket.AF_INET6
80
allow_reuse_address = True
81
server_bind = server_bind
82
def verify_request(self, request, client_address):
83
print "UDP request came"
84
return request[0] == "Marco"
361
87
class tcp_handler(SocketServer.BaseRequestHandler, object):
362
"""A TCP request handler class.
363
Instantiated by IPv6_TCPServer for each request to handle it.
364
Note: This will run in its own forked process."""
367
logger.debug(u"TCP connection from: %s",
368
unicode(self.client_address))
369
session = gnutls.connection.ClientSession(self.request,
373
#priority = ':'.join(("NONE", "+VERS-TLS1.1", "+AES-256-CBC",
374
# "+SHA1", "+COMP-NULL", "+CTYPE-OPENPGP",
377
if self.server.options.priority:
378
priority = self.server.options.priority
379
gnutls.library.functions.gnutls_priority_set_direct\
380
(session._c_object, priority, None);
384
except gnutls.errors.GNUTLSError, error:
385
logger.debug(u"Handshake failed: %s", error)
386
# Do not run session.bye() here: the session is not
387
# established. Just abandon the request.
390
fpr = fingerprint(peer_certificate(session))
391
except (TypeError, gnutls.errors.GNUTLSError), error:
392
logger.debug(u"Bad certificate: %s", error)
395
logger.debug(u"Fingerprint: %s", fpr)
397
for c in self.server.clients:
398
if c.fingerprint == fpr:
401
# Have to check if client.still_valid(), since it is possible
402
# that the client timed out while establishing the GnuTLS
404
if (not client) or (not client.still_valid()):
406
logger.debug(u"Client %(name)s is invalid",
409
logger.debug(u"Client not found for fingerprint: %s",
414
while sent_size < len(client.secret):
415
sent = session.send(client.secret[sent_size:])
416
logger.debug(u"Sent: %d, remaining: %d",
417
sent, len(client.secret)
418
- (sent_size + sent))
89
print "TCP request came"
90
print "Request:", self.request
91
print "Client Address:", self.client_address
92
print "Server:", self.server
93
session = gnutls.connection.ServerSession(self.request,
94
self.server.credentials)
96
if session.peer_certificate:
97
print "DN:", session.peer_certificate.subject
100
except gnutls.errors.CertificateError, error:
101
print "Verify failed", error
105
session.send(dict((client.dn, client.password)
106
for client in self.server.clients)
107
[session.peer_certificate.subject])
109
session.send("gazonk")
423
113
class IPv6_TCPServer(SocketServer.ForkingTCPServer, object):
424
"""IPv6 TCP server. Accepts 'None' as address and/or port.
426
options: Command line options
427
clients: Set() of Client objects
114
__init__ = init_with_options
429
115
address_family = socket.AF_INET6
430
def __init__(self, *args, **kwargs):
431
if "options" in kwargs:
432
self.options = kwargs["options"]
433
del kwargs["options"]
434
if "clients" in kwargs:
435
self.clients = kwargs["clients"]
436
del kwargs["clients"]
437
return super(type(self), self).__init__(*args, **kwargs)
438
def server_bind(self):
439
"""This overrides the normal server_bind() function
440
to bind to an interface if one was specified, and also NOT to
441
bind to an address or port if they were not specified."""
442
if self.options.interface:
443
if not hasattr(socket, "SO_BINDTODEVICE"):
444
# From /usr/include/asm-i486/socket.h
445
socket.SO_BINDTODEVICE = 25
447
self.socket.setsockopt(socket.SOL_SOCKET,
448
socket.SO_BINDTODEVICE,
449
self.options.interface)
450
except socket.error, error:
451
if error[0] == errno.EPERM:
452
logger.warning(u"No permission to"
453
u" bind to interface %s",
454
self.options.interface)
457
# Only bind(2) the socket if we really need to.
458
if self.server_address[0] or self.server_address[1]:
459
if not self.server_address[0]:
461
self.server_address = (in6addr_any,
462
self.server_address[1])
463
elif self.server_address[1] is None:
464
self.server_address = (self.server_address[0],
466
return super(type(self), self).server_bind()
116
allow_reuse_address = True
117
request_queue_size = 1024
118
server_bind = server_bind
469
125
def string_to_delta(interval):
470
126
"""Parse a string and return a datetime.timedelta
504
"""Derived from the Avahi example code"""
505
global group, serviceName, serviceType, servicePort, serviceTXT, \
508
group = dbus.Interface(
509
bus.get_object( avahi.DBUS_NAME,
510
server.EntryGroupNew()),
511
avahi.DBUS_INTERFACE_ENTRY_GROUP)
512
group.connect_to_signal('StateChanged',
513
entry_group_state_changed)
514
logger.debug(u"Adding service '%s' of type '%s' ...",
515
serviceName, serviceType)
518
serviceInterface, # interface
519
avahi.PROTO_INET6, # protocol
520
dbus.UInt32(0), # flags
521
serviceName, serviceType,
523
dbus.UInt16(servicePort),
524
avahi.string_array_to_txt_array(serviceTXT))
528
def remove_service():
529
"""From the Avahi example code"""
532
if not group is None:
536
def server_state_changed(state):
537
"""Derived from the Avahi example code"""
538
if state == avahi.SERVER_COLLISION:
539
logger.warning(u"Server name collision")
541
elif state == avahi.SERVER_RUNNING:
545
def entry_group_state_changed(state, error):
546
"""Derived from the Avahi example code"""
547
global serviceName, server, rename_count
549
logger.debug(u"state change: %i", state)
551
if state == avahi.ENTRY_GROUP_ESTABLISHED:
552
logger.debug(u"Service established.")
553
elif state == avahi.ENTRY_GROUP_COLLISION:
555
rename_count = rename_count - 1
557
name = server.GetAlternativeServiceName(name)
558
logger.warning(u"Service name collision, "
559
u"changing name to '%s' ...", name)
564
logger.error(u"No suitable service name found after %i"
565
u" retries, exiting.", n_rename)
567
elif state == avahi.ENTRY_GROUP_FAILURE:
568
logger.error(u"Error in group state changed %s",
573
def if_nametoindex(interface):
574
"""Call the C function if_nametoindex()"""
576
libc = ctypes.cdll.LoadLibrary("libc.so.6")
577
return libc.if_nametoindex(interface)
578
except (OSError, AttributeError):
579
if "struct" not in sys.modules:
581
if "fcntl" not in sys.modules:
583
SIOCGIFINDEX = 0x8933 # From /usr/include/linux/sockios.h
585
ifreq = fcntl.ioctl(s, SIOCGIFINDEX,
586
struct.pack("16s16x", interface))
588
interface_index = struct.unpack("I", ifreq[16:20])[0]
589
return interface_index
592
def daemon(nochdir, noclose):
593
"""See daemon(3). Standard BSD Unix function.
594
This should really exist as os.daemon, but it doesn't (yet)."""
601
# Close all standard open file descriptors
602
null = os.open("/dev/null", os.O_NOCTTY | os.O_RDWR)
603
if not stat.S_ISCHR(os.fstat(null).st_mode):
604
raise OSError(errno.ENODEV,
605
"/dev/null not a character device")
606
os.dup2(null, sys.stdin.fileno())
607
os.dup2(null, sys.stdout.fileno())
608
os.dup2(null, sys.stderr.fileno())
613
def killme(status = 0):
614
logger.debug("Stopping server with exit status %d", status)
616
if main_loop_started:
625
global main_loop_started
626
main_loop_started = False
628
159
parser = OptionParser()
629
160
parser.add_option("-i", "--interface", type="string",
630
default=None, metavar="IF",
631
help="Bind to interface IF")
632
parser.add_option("-a", "--address", type="string", default=None,
633
help="Address to listen for requests on")
634
parser.add_option("-p", "--port", type="int", default=None,
161
default="eth0", metavar="IF",
162
help="Interface to bind to")
163
parser.add_option("--cert", type="string", default="cert.pem",
165
help="Public key certificate to use")
166
parser.add_option("--key", type="string", default="key.pem",
168
help="Private key to use")
169
parser.add_option("--ca", type="string", default="ca.pem",
171
help="Certificate Authority certificate to use")
172
parser.add_option("--crl", type="string", default="crl.pem",
174
help="Certificate Revokation List to use")
175
parser.add_option("-p", "--port", type="int", default=49001,
635
176
help="Port number to receive requests on")
177
parser.add_option("--dh", type="int", metavar="BITS",
178
help="DH group to use")
179
parser.add_option("-t", "--timeout", type="string", # Parsed later
181
help="Amount of downtime allowed for clients")
182
parser.add_option("--interval", type="string", # Parsed later
184
help="How often to check that a client is up")
636
185
parser.add_option("--check", action="store_true", default=False,
637
186
help="Run self-test")
638
parser.add_option("--debug", action="store_true", default=False,
640
parser.add_option("--priority", type="string",
642
help="GnuTLS priority string"
643
" (see GnuTLS documentation)")
644
parser.add_option("--servicename", type="string",
645
default="Mandos", help="Zeroconf service name")
646
187
(options, args) = parser.parse_args()
648
189
if options.check:
650
191
doctest.testmod()
194
# Parse the time arguments
196
options.timeout = string_to_delta(options.timeout)
198
parser.error("option --timeout: Unparseable time")
201
options.interval = string_to_delta(options.interval)
203
parser.error("option --interval: Unparseable time")
205
cert = gnutls.crypto.X509Certificate(open(options.cert).read())
206
key = gnutls.crypto.X509PrivateKey(open(options.key).read())
207
ca = gnutls.crypto.X509Certificate(open(options.ca).read())
208
crl = gnutls.crypto.X509CRL(open(options.crl).read())
209
cred = gnutls.connection.X509Credentials(cert, key, [ca], [crl])
653
211
# Parse config file
654
defaults = { "timeout": "1h",
656
"checker": "fping -q -- %%(fqdn)s",
658
client_config = ConfigParser.SafeConfigParser(defaults)
659
#client_config.readfp(open("global.conf"), "global.conf")
660
client_config.read("mandos-clients.conf")
663
serviceName = options.servicename;
668
# From the Avahi example code
669
DBusGMainLoop(set_as_default=True )
670
main_loop = gobject.MainLoop()
671
bus = dbus.SystemBus()
672
server = dbus.Interface(
673
bus.get_object( avahi.DBUS_NAME, avahi.DBUS_PATH_SERVER ),
674
avahi.DBUS_INTERFACE_SERVER )
675
# End of Avahi example code
677
debug = options.debug
680
console = logging.StreamHandler()
681
# console.setLevel(logging.DEBUG)
682
console.setFormatter(logging.Formatter\
683
('%(levelname)s: %(message)s'))
684
logger.addHandler(console)
688
def remove_from_clients(client):
689
clients.remove(client)
691
logger.debug(u"No clients left, exiting")
694
clients.update(Set(Client(name=section,
695
stop_hook = remove_from_clients,
696
**(dict(client_config\
698
for section in client_config.sections()))
704
"Cleanup function; run on exit"
706
# From the Avahi example code
707
if not group is None:
710
# End of Avahi example code
713
client = clients.pop()
714
client.stop_hook = None
717
atexit.register(cleanup)
720
signal.signal(signal.SIGINT, signal.SIG_IGN)
721
signal.signal(signal.SIGHUP, lambda signum, frame: killme())
722
signal.signal(signal.SIGTERM, lambda signum, frame: killme())
724
for client in clients:
727
tcp_server = IPv6_TCPServer((options.address, options.port),
213
client_config_object = ConfigParser.SafeConfigParser(defaults)
214
client_config_object.read("mandos-clients.conf")
215
clients = [Client(name=section,
216
**(dict(client_config_object.items(section))))
217
for section in client_config_object.sections()]
219
udp_server = IPv6_UDPServer((in6addr_any, options.port),
223
tcp_server = IPv6_TCPServer((in6addr_any, options.port),
731
# Find out what random port we got
733
servicePort = tcp_server.socket.getsockname()[1]
734
logger.debug(u"Now listening on port %d", servicePort)
736
if options.interface is not None:
737
global serviceInterface
738
serviceInterface = if_nametoindex(options.interface)
740
# From the Avahi example code
741
server.connect_to_signal("StateChanged", server_state_changed)
743
server_state_changed(server.GetState())
744
except dbus.exceptions.DBusException, error:
745
logger.critical(u"DBusException: %s", error)
747
# End of Avahi example code
749
gobject.io_add_watch(tcp_server.fileno(), gobject.IO_IN,
750
lambda *args, **kwargs:
751
tcp_server.handle_request(*args[2:],
754
logger.debug("Starting main loop")
755
main_loop_started = True
757
except KeyboardInterrupt:
763
if __name__ == '__main__':
230
in_, out, err = select.select((udp_server,
233
server.handle_request()
236
if __name__ == "__main__":