/mandos/release : revision 41

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# This program is partly derived from an example program for an Avahi

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# service publisher, downloaded from

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# <http://avahi.org/wiki/PythonPublishExample>. This includes the

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# methods "add" and "remove" in the "AvahiService" class, the

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# "server_state_changed" and "entry_group_state_changed" functions,

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# and some lines in "main".

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# following functions: "AvahiService.add", "AvahiService.remove",

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# "server_state_changed", "entry_group_state_changed", and some lines

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# in "main".

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#

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# Everything else is

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# GNU General Public License for more details.

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#

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# You should have received a copy of the GNU General Public License

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# along with this program. If not, see

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# <http://www.gnu.org/licenses/>.

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# along with this program. If not, see <http://www.gnu.org/licenses/>.

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#

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# Contact the authors at <mandos@fukt.bsnet.se>.

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#

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from dbus.mainloop.glib import DBusGMainLoop

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import ctypes

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version = "1.0"

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# Brief description of the operation of this program:

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#

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# This server announces itself as a Zeroconf service. Connecting

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# clients use the TLS protocol, with the unusual quirk that this

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# server program acts as a TLS "client" while a connecting client acts

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# as a TLS "server". The client (acting as a TLS "server") must

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# supply an OpenPGP certificate, and the fingerprint of this

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# certificate is used by this server to look up (in a list read from a

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# file at start time) which binary blob to give the client. No other

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# authentication or authorization is done by this server.

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logger = logging.Logger('mandos')

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syslogger = logging.handlers.SysLogHandler\

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(facility = logging.handlers.SysLogHandler.LOG_DAEMON,

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address = "/dev/log")

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(facility = logging.handlers.SysLogHandler.LOG_DAEMON)

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syslogger.setFormatter(logging.Formatter\

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('Mandos: %(levelname)s: %(message)s'))

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('%(levelname)s: %(message)s'))

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logger.addHandler(syslogger)

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del syslogger

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console = logging.StreamHandler()

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console.setFormatter(logging.Formatter('%(name)s: %(levelname)s:'

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' %(message)s'))

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logger.addHandler(console)

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class AvahiError(Exception):

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def __init__(self, value):

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class AvahiService(object):

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"""An Avahi (Zeroconf) service.

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Attributes:

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"""

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interface: integer; avahi.IF_UNSPEC or an interface index.

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Used to optionally bind to the specified interface.

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name: string; Example: 'Mandos'

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type: string; Example: '_mandos._tcp'.

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See <http://www.dns-sd.org/ServiceTypes.html>

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port: integer; what port to announce

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TXT: list of strings; TXT record for the service

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domain: string; Domain to publish on, default to .local if empty.

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host: string; Host to publish records for, default is localhost

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max_renames: integer; maximum number of renames

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rename_count: integer; counter so we only rename after collisions

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a sensible number of times

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name = string; Example: "Mandos"

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type = string; Example: "_mandos._tcp".

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See <http://www.dns-sd.org/ServiceTypes.html>

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port = integer; what port to announce

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TXT = list of strings; TXT record for the service

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domain = string; Domain to publish on, default to .local if empty.

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host = string; Host to publish records for, default to localhost

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if empty.

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max_renames = integer; maximum number of renames

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rename_count = integer; counter so we only rename after collisions

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a sensible number of times

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"""

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def __init__(self, interface = avahi.IF_UNSPEC, name = None,

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type = None, port = None, TXT = None, domain = "",

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host = "", max_renames = 32768):

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host = "", max_renames = 12):

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"""An Avahi (Zeroconf) service. """

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self.interface = interface

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self.name = name

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self.type = type

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self.domain = domain

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self.host = host

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self.rename_count = 0

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self.max_renames = max_renames

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def rename(self):

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"""Derived from the Avahi example code"""

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if self.rename_count >= self.max_renames:

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logger.critical(u"No suitable Zeroconf service name found"

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u" after %i retries, exiting.",

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rename_count)

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logger.critical(u"No suitable service name found after %i"

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u" retries, exiting.", rename_count)

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raise AvahiServiceError("Too many renames")

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self.name = server.GetAlternativeServiceName(self.name)

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logger.info(u"Changing Zeroconf service name to %r ...",

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str(self.name))

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syslogger.setFormatter(logging.Formatter\

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('Mandos (%s): %%(levelname)s:'

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' %%(message)s' % self.name))

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name = server.GetAlternativeServiceName(name)

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logger.notice(u"Changing name to %r ...", name)

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self.remove()

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self.add()

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self.rename_count += 1

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avahi.DBUS_INTERFACE_ENTRY_GROUP)

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group.connect_to_signal('StateChanged',

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entry_group_state_changed)

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logger.debug(u"Adding Zeroconf service '%s' of type '%s' ...",

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logger.debug(u"Adding service '%s' of type '%s' ...",

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service.name, service.type)

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group.AddService(

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self.interface, # interface

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fingerprint: string (40 or 32 hexadecimal digits); used to

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uniquely identify the client

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secret: bytestring; sent verbatim (over TLS) to client

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host: string; available for use by the checker command

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fqdn: string (FQDN); available for use by the checker command

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created: datetime.datetime(); object creation, not client host

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last_checked_ok: datetime.datetime() or None if not yet checked OK

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timeout: datetime.timedelta(); How long from last_checked_ok

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interval = property(lambda self: self._interval,

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_set_interval)

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del _set_interval

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def __init__(self, name = None, stop_hook=None, config={}):

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"""Note: the 'checker' key in 'config' sets the

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'checker_command' attribute and *not* the 'checker'

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attribute."""

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def __init__(self, name=None, stop_hook=None, fingerprint=None,

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secret=None, secfile=None, fqdn=None, timeout=None,

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interval=-1, checker=None):

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"""Note: the 'checker' argument sets the 'checker_command'

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attribute and not the 'checker' attribute.."""

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self.name = name

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logger.debug(u"Creating client %r", self.name)

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# Uppercase and remove spaces from fingerprint for later

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# comparison purposes with return value from the fingerprint()

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# function

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self.fingerprint = config["fingerprint"].upper()\

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.replace(u" ", u"")

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# Uppercase and remove spaces from fingerprint

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# for later comparison purposes with return value of

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# the fingerprint() function

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self.fingerprint = fingerprint.upper().replace(u" ", u"")

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logger.debug(u" Fingerprint: %s", self.fingerprint)

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if "secret" in config:

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self.secret = config["secret"].decode(u"base64")

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elif "secfile" in config:

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sf = open(config["secfile"])

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if secret:

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self.secret = secret.decode(u"base64")

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elif secfile:

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sf = open(secfile)

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self.secret = sf.read()

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sf.close()

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else:

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raise TypeError(u"No secret or secfile for client %s"

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% self.name)

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self.host = config.get("host", "")

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self.fqdn = fqdn

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self.created = datetime.datetime.now()

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self.last_checked_ok = None

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self.timeout = string_to_delta(config["timeout"])

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self.interval = string_to_delta(config["interval"])

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self.timeout = string_to_delta(timeout)

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self.interval = string_to_delta(interval)

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self.stop_hook = stop_hook

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self.checker = None

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self.checker_initiator_tag = None

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self.stop_initiator_tag = None

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self.checker_callback_tag = None

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self.check_command = config["checker"]

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self.check_command = checker

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def start(self):

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"""Start this client's checker and timeout hooks"""

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# Schedule a new checker to be started an 'interval' from now,

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The possibility that a client might be restarted is left open,

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but not currently used."""

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# If this client doesn't have a secret, it is already stopped.

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if hasattr(self, "secret") and self.secret:

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logger.info(u"Stopping client %s", self.name)

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if self.secret:

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logger.debug(u"Stopping client %s", self.name)

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self.secret = None

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else:

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return False

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self.checker = None

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if os.WIFEXITED(condition) \

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and (os.WEXITSTATUS(condition) == 0):

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logger.info(u"Checker for %(name)s succeeded",

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vars(self))

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logger.debug(u"Checker for %(name)s succeeded",

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vars(self))

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self.last_checked_ok = now

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gobject.source_remove(self.stop_initiator_tag)

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self.stop_initiator_tag = gobject.timeout_add\

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logger.warning(u"Checker for %(name)s crashed?",

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vars(self))

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else:

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logger.info(u"Checker for %(name)s failed",

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vars(self))

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logger.debug(u"Checker for %(name)s failed",

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vars(self))

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def start_checker(self):

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"""Start a new checker subprocess if one is not running.

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If a checker already exists, leave it running and do

325

if self.checker is None:

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try:

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# In case check_command has exactly one % operator

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command = self.check_command % self.host

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command = self.check_command % self.fqdn

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except TypeError:

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# Escape attributes for the shell

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escaped_attrs = dict((key, re.escape(str(val)))

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u' %s', self.check_command, error)

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return True # Try again later

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try:

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logger.info(u"Starting checker %r for %s",

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command, self.name)

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# We don't need to redirect stdout and stderr, since

344

# in normal mode, that is already done by daemon(),

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# and in debug mode we don't want to. (Stdin is

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# always replaced by /dev/null.)

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logger.debug(u"Starting checker %r for %s",

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command, self.name)

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self.checker = subprocess.Popen(command,

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close_fds=True,

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shell=True, cwd="/")

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self.checker_callback_tag = gobject.child_watch_add\

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(self.checker.pid,

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self.checker_callback)

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except OSError, error:

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except subprocess.OSError, error:

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logger.error(u"Failed to start subprocess: %s",

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error)

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# Re-run this periodically if run by gobject.timeout_add

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self.checker_callback_tag = None

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if getattr(self, "checker", None) is None:

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return

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logger.debug(u"Stopping checker for %(name)s", vars(self))

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logger.debug("Stopping checker for %(name)s", vars(self))

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try:

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os.kill(self.checker.pid, signal.SIGTERM)

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#os.sleep(0.5)

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def fingerprint(openpgp):

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"Convert an OpenPGP bytestring to a hexdigit fingerprint string"

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# New empty GnuTLS certificate

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crt = gnutls.library.types.gnutls_openpgp_crt_t()

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gnutls.library.functions.gnutls_openpgp_crt_init\

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(ctypes.byref(crt))

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# New GnuTLS "datum" with the OpenPGP public key

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datum = gnutls.library.types.gnutls_datum_t\

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(ctypes.cast(ctypes.c_char_p(openpgp),

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ctypes.POINTER(ctypes.c_ubyte)),

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ctypes.c_uint(len(openpgp)))

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# New empty GnuTLS certificate

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crt = gnutls.library.types.gnutls_openpgp_crt_t()

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gnutls.library.functions.gnutls_openpgp_crt_init\

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(ctypes.byref(crt))

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# Import the OpenPGP public key into the certificate

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gnutls.library.functions.gnutls_openpgp_crt_import\

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(crt, ctypes.byref(datum),

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gnutls.library.constants.GNUTLS_OPENPGP_FMT_RAW)

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# Verify the self signature in the key

417

crtverify = ctypes.c_uint();

418

gnutls.library.functions.gnutls_openpgp_crt_verify_self\

419

(crt, 0, ctypes.byref(crtverify))

420

if crtverify.value != 0:

421

gnutls.library.functions.gnutls_openpgp_crt_deinit(crt)

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raise gnutls.errors.CertificateSecurityError("Verify failed")

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ret = gnutls.library.functions.gnutls_openpgp_crt_import\

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(crt,

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ctypes.byref(datum),

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gnutls.library.constants.GNUTLS_OPENPGP_FMT_RAW)

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# New buffer for the fingerprint

424

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buffer = ctypes.create_string_buffer(20)

425

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buffer_length = ctypes.c_size_t()

441

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Note: This will run in its own forked process."""

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def handle(self):

444

logger.info(u"TCP connection from: %s",

434

logger.debug(u"TCP connection from: %s",

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unicode(self.client_address))

446

436

session = gnutls.connection.ClientSession\

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(self.request, gnutls.connection.X509Credentials())

473

463

try:

474

464

session.handshake()

475

465

except gnutls.errors.GNUTLSError, error:

476

logger.warning(u"Handshake failed: %s", error)

466

logger.debug(u"Handshake failed: %s", error)

477

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# Do not run session.bye() here: the session is not

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# established. Just abandon the request.

479

469

return

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try:

481

471

fpr = fingerprint(peer_certificate(session))

482

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except (TypeError, gnutls.errors.GNUTLSError), error:

483

logger.warning(u"Bad certificate: %s", error)

473

logger.debug(u"Bad certificate: %s", error)

484

474

session.bye()

485

475

return

486

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logger.debug(u"Fingerprint: %s", fpr)

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480

client = c

491

481

break

492

482

if not client:

493

logger.warning(u"Client not found for fingerprint: %s",

494

fpr)

483

logger.debug(u"Client not found for fingerprint: %s", fpr)

495

484

session.bye()

496

485

return

497

486

# Have to check if client.still_valid(), since it is possible

498

487

# that the client timed out while establishing the GnuTLS

499

488

# session.

500

489

if not client.still_valid():

501

logger.warning(u"Client %(name)s is invalid",

502

vars(client))

490

logger.debug(u"Client %(name)s is invalid", vars(client))

503

491

session.bye()

504

492

return

505

493

sent_size = 0

540

528

self.settings["interface"])

541

529

except socket.error, error:

542

530

if error[0] == errno.EPERM:

543

logger.error(u"No permission to"

544

u" bind to interface %s",

545

self.settings["interface"])

531

logger.warning(u"No permission to"

532

u" bind to interface %s",

533

self.settings["interface"])

546

534

else:

547

535

raise error

548

536

# Only bind(2) the socket if we really need to.

551

539

in6addr_any = "::"

552

540

self.server_address = (in6addr_any,

553

541

self.server_address[1])

554

elif not self.server_address[1]:

542

elif self.server_address[1] is None:

555

543

self.server_address = (self.server_address[0],

556

544

0)

557

# if self.settings["interface"]:

558

# self.server_address = (self.server_address[0],

559

# 0, # port

560

# 0, # flowinfo

561

# if_nametoindex

562

# (self.settings

563

# ["interface"]))

564

545

return super(type(self), self).server_bind()

565

546

566

547

577

558

datetime.timedelta(1)

578

559

>>> string_to_delta(u'1w')

579

560

datetime.timedelta(7)

580

>>> string_to_delta('5m 30s')

581

datetime.timedelta(0, 330)

582

561

"""

583

timevalue = datetime.timedelta(0)

584

for s in interval.split():

585

try:

586

suffix=unicode(s[-1])

587

value=int(s[:-1])

588

if suffix == u"d":

589

delta = datetime.timedelta(value)

590

elif suffix == u"s":

591

delta = datetime.timedelta(0, value)

592

elif suffix == u"m":

593

delta = datetime.timedelta(0, 0, 0, 0, value)

594

elif suffix == u"h":

595

delta = datetime.timedelta(0, 0, 0, 0, 0, value)

596

elif suffix == u"w":

597

delta = datetime.timedelta(0, 0, 0, 0, 0, 0, value)

598

else:

599

raise ValueError

600

except (ValueError, IndexError):

562

try:

563

suffix=unicode(interval[-1])

564

value=int(interval[:-1])

565

if suffix == u"d":

566

delta = datetime.timedelta(value)

567

elif suffix == u"s":

568

delta = datetime.timedelta(0, value)

569

elif suffix == u"m":

570

delta = datetime.timedelta(0, 0, 0, 0, value)

571

elif suffix == u"h":

572

delta = datetime.timedelta(0, 0, 0, 0, 0, value)

573

elif suffix == u"w":

574

delta = datetime.timedelta(0, 0, 0, 0, 0, 0, value)

575

else:

601

576

raise ValueError

602

timevalue += delta

603

return timevalue

577

except (ValueError, IndexError):

578

raise ValueError

579

return delta

604

580

605

581

606

582

def server_state_changed(state):

607

583

"""Derived from the Avahi example code"""

608

584

if state == avahi.SERVER_COLLISION:

609

logger.error(u"Zeroconf server name collision")

585

logger.warning(u"Server name collision")

610

586

service.remove()

611

587

elif state == avahi.SERVER_RUNNING:

612

588

service.add()

614

590

615

591

def entry_group_state_changed(state, error):

616

592

"""Derived from the Avahi example code"""

617

logger.debug(u"Avahi state change: %i", state)

593

logger.debug(u"state change: %i", state)

618

594

619

595

if state == avahi.ENTRY_GROUP_ESTABLISHED:

620

logger.debug(u"Zeroconf service established.")

596

logger.debug(u"Service established.")

621

597

elif state == avahi.ENTRY_GROUP_COLLISION:

622

logger.warning(u"Zeroconf service name collision.")

598

logger.warning(u"Service name collision.")

623

599

service.rename()

624

600

elif state == avahi.ENTRY_GROUP_FAILURE:

625

logger.critical(u"Avahi: Error in group state changed %s",

601

logger.critical(u"Error in group state changed %s",

626

602

unicode(error))

627

603

raise AvahiGroupError("State changed: %s", str(error))

628

604

651

627

return if_nametoindex(interface)

652

628

653

629

654

def daemon(nochdir = False, noclose = False):

630

def daemon(nochdir, noclose):

655

631

"""See daemon(3). Standard BSD Unix function.

656

632

This should really exist as os.daemon, but it doesn't (yet)."""

657

633

if os.fork():

659

635

os.setsid()

660

636

if not nochdir:

661

637

os.chdir("/")

662

if os.fork():

663

sys.exit()

664

638

if not noclose:

665

639

# Close all standard open file descriptors

666

640

null = os.open(os.path.devnull, os.O_NOCTTY | os.O_RDWR)

678

652

global main_loop_started

679

653

main_loop_started = False

680

654

681

parser = OptionParser(version = "%%prog %s" % version)

655

parser = OptionParser()

682

656

parser.add_option("-i", "--interface", type="string",

683

657

metavar="IF", help="Bind to interface IF")

684

658

parser.add_option("-a", "--address", type="string",

687

661

help="Port number to receive requests on")

688

662

parser.add_option("--check", action="store_true", default=False,

689

663

help="Run self-test")

690

parser.add_option("--debug", action="store_true",

664

parser.add_option("--debug", action="store_true", default=False,

691

665

help="Debug mode; run in foreground and log to"

692

666

" terminal")

693

667

parser.add_option("--priority", type="string", help="GnuTLS"

718

692

# Parse config file for server-global settings

719

693

server_config = ConfigParser.SafeConfigParser(server_defaults)

720

694

del server_defaults

721

server_config.read(os.path.join(options.configdir, "mandos.conf"))

695

server_config.read(os.path.join(options.configdir, "server.conf"))

696

server_section = "server"

722

697

# Convert the SafeConfigParser object to a dict

723

server_settings = server_config.defaults()

698

server_settings = dict(server_config.items(server_section))

724

699

# Use getboolean on the boolean config option

725

700

server_settings["debug"] = server_config.getboolean\

726

("DEFAULT", "debug")

701

(server_section, "debug")

727

702

del server_config

728

703

729

704

# Override the settings from the config file with command line

736

711

del options

737

712

# Now we have our good server settings in "server_settings"

738

713

739

debug = server_settings["debug"]

740

741

if not debug:

742

syslogger.setLevel(logging.WARNING)

743

console.setLevel(logging.WARNING)

744

745

if server_settings["servicename"] != "Mandos":

746

syslogger.setFormatter(logging.Formatter\

747

('Mandos (%s): %%(levelname)s:'

748

' %%(message)s'

749

% server_settings["servicename"]))

750

751

714

# Parse config file with clients

752

715

client_defaults = { "timeout": "1h",

753

716

"interval": "5m",

754

"checker": "fping -q -- %(host)s",

755

"host": "",

717

"checker": "fping -q -- %%(fqdn)s",

756

718

}

757

719

client_config = ConfigParser.SafeConfigParser(client_defaults)

758

720

client_config.read(os.path.join(server_settings["configdir"],

762

724

service = AvahiService(name = server_settings["servicename"],

763

725

type = "_mandos._tcp", );

764

726

if server_settings["interface"]:

765

service.interface = if_nametoindex\

766

(server_settings["interface"])

727

service.interface = if_nametoindex(server_settings["interface"])

767

728

768

729

global main_loop

769

730

global bus

772

733

DBusGMainLoop(set_as_default=True )

773

734

main_loop = gobject.MainLoop()

774

735

bus = dbus.SystemBus()

775

server = dbus.Interface(bus.get_object(avahi.DBUS_NAME,

776

avahi.DBUS_PATH_SERVER),

777

avahi.DBUS_INTERFACE_SERVER)

736

server = dbus.Interface(

737

bus.get_object( avahi.DBUS_NAME, avahi.DBUS_PATH_SERVER ),

738

avahi.DBUS_INTERFACE_SERVER )

778

739

# End of Avahi example code

779

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

780

751

clients = Set()

781

752

def remove_from_clients(client):

782

753

clients.remove(client)

783

754

if not clients:

784

logger.critical(u"No clients left, exiting")

755

logger.debug(u"No clients left, exiting")

785

756

sys.exit()

786

757

787

clients.update(Set(Client(name = section,

758

clients.update(Set(Client(name=section,

788

759

stop_hook = remove_from_clients,

789

config

790

= dict(client_config.items(section)))

760

**(dict(client_config\

761

.items(section))))

791

762

for section in client_config.sections()))

792

if not clients:

793

logger.critical(u"No clients defined")

794

sys.exit(1)

795

796

if debug:

797

# Redirect stdin so all checkers get /dev/null

798

null = os.open(os.path.devnull, os.O_NOCTTY | os.O_RDWR)

799

os.dup2(null, sys.stdin.fileno())

800

if null > 2:

801

os.close(null)

802

else:

803

# No console logging

804

logger.removeHandler(console)

805

# Close all input and output, do double fork, etc.

806

daemon()

807

808

pidfilename = "/var/run/mandos/mandos.pid"

809

pid = os.getpid()

810

try:

811

pidfile = open(pidfilename, "w")

812

pidfile.write(str(pid) + "\n")

813

pidfile.close()

814

del pidfile

815

except IOError, err:

816

logger.error(u"Could not write %s file with PID %d",

817

pidfilename, os.getpid())

763

764

if not debug:

765

daemon(False, False)

818

766

819

767

def cleanup():

820

768

"Cleanup function; run on exit"

847

795

clients=clients)

848

796

# Find out what port we got

849

797

service.port = tcp_server.socket.getsockname()[1]

850

logger.info(u"Now listening on address %r, port %d, flowinfo %d,"

851

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())

852

800

853

801

#service.interface = tcp_server.socket.getsockname()[3]

854

802

867

815

tcp_server.handle_request\

868

816

(*args[2:], **kwargs) or True)

869

817

870

logger.debug(u"Starting main loop")

818

logger.debug("Starting main loop")

871

819

main_loop_started = True

872

820

main_loop.run()

873

821

except AvahiError, error: