/mandos/trunk : revision 88

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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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# 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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# 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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#

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# Everything else is

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from dbus.mainloop.glib import DBusGMainLoop

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import ctypes

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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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version = "1.0"

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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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(facility = logging.handlers.SysLogHandler.LOG_DAEMON,

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address = "/dev/log")

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syslogger.setFormatter(logging.Formatter\

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

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('Mandos: %(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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"""

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"""An Avahi (Zeroconf) service.

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Attributes:

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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 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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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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"""

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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 = 12):

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

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host = "", max_renames = 32768):

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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 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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name = server.GetAlternativeServiceName(name)

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

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

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logger.info(u"Changing name to %r ...", 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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self.remove()

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self.add()

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self.rename_count += 1

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

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host: string; 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, 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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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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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

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

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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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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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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.fqdn = fqdn

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

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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(timeout)

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self.interval = string_to_delta(interval)

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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.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 = checker

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self.check_command = config["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 self.secret:

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

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

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vars(self))

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

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vars(self))

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logger.info(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

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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.fqdn

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command = self.check_command % self.host

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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:

341

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

342

command, self.name)

338

logger.info(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 = None

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

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return

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

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

362

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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

409

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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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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# New buffer for the fingerprint

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buffer = ctypes.create_string_buffer(20)

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buffer_length = ctypes.c_size_t()

431

427

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

432

428

433

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def handle(self):

434

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

430

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

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unicode(self.client_address))

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session = gnutls.connection.ClientSession\

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

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line = self.request.makefile().readline()

436

logger.debug(u"Protocol version: %r", line)

437

try:

438

if int(line.strip().split()[0]) > 1:

439

raise RuntimeError

440

except (ValueError, IndexError, RuntimeError), error:

441

logger.error(u"Unknown protocol version: %s", error)

442

return

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# Note: gnutls.connection.X509Credentials is really a generic

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# GnuTLS certificate credentials object so long as no X.509

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# keys are added to it. Therefore, we can use it here despite

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459

try:

454

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session.handshake()

455

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except gnutls.errors.GNUTLSError, error:

456

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

462

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

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

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# established. Just abandon the request.

459

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return

460

466

try:

461

467

fpr = fingerprint(peer_certificate(session))

462

468

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

463

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

469

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

464

470

session.bye()

465

471

return

466

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

470

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client = c

471

477

break

472

478

if not client:

473

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

479

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

480

fpr)

474

481

session.bye()

475

482

return

476

483

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

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# that the client timed out while establishing the GnuTLS

478

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# session.

479

486

if not client.still_valid():

480

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

487

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

488

vars(client))

481

489

session.bye()

482

490

return

483

491

sent_size = 0

518

526

self.settings["interface"])

519

527

except socket.error, error:

520

528

if error[0] == errno.EPERM:

521

logger.warning(u"No permission to"

522

u" bind to interface %s",

523

self.settings["interface"])

529

logger.error(u"No permission to"

530

u" bind to interface %s",

531

self.settings["interface"])

524

532

else:

525

533

raise error

526

534

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

529

537

in6addr_any = "::"

530

538

self.server_address = (in6addr_any,

531

539

self.server_address[1])

532

elif self.server_address[1] is None:

540

elif not self.server_address[1]:

533

541

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

534

542

0)

543

# if self.settings["interface"]:

544

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

545

# 0, # port

546

# 0, # flowinfo

547

# if_nametoindex

548

# (self.settings

549

# ["interface"]))

535

550

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

536

551

537

552

572

587

def server_state_changed(state):

573

588

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

574

589

if state == avahi.SERVER_COLLISION:

575

logger.warning(u"Server name collision")

590

logger.error(u"Server name collision")

576

591

service.remove()

577

592

elif state == avahi.SERVER_RUNNING:

578

593

service.add()

592

607

unicode(error))

593

608

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

594

609

595

def if_nametoindex(interface, _func=[None]):

610

def if_nametoindex(interface):

596

611

"""Call the C function if_nametoindex(), or equivalent"""

597

if _func[0] is not None:

598

return _func[0](interface)

612

global if_nametoindex

599

613

try:

600

614

if "ctypes.util" not in sys.modules:

601

615

import ctypes.util

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

616

if_nametoindex = ctypes.cdll.LoadLibrary\

617

(ctypes.util.find_library("c")).if_nametoindex

611

618

except (OSError, AttributeError):

612

619

if "struct" not in sys.modules:

613

620

import struct

614

621

if "fcntl" not in sys.modules:

615

622

import fcntl

616

def the_hard_way(interface):

623

def if_nametoindex(interface):

617

624

"Get an interface index the hard way, i.e. using fcntl()"

618

625

SIOCGIFINDEX = 0x8933 # From /usr/include/linux/sockios.h

619

626

s = socket.socket()

622

629

s.close()

623

630

interface_index = struct.unpack("I", ifreq[16:20])[0]

624

631

return interface_index

625

_func[0] = the_hard_way

626

return _func[0](interface)

627

628

629

def daemon(nochdir, noclose):

632

return if_nametoindex(interface)

633

634

635

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

630

636

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

631

637

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

632

638

if os.fork():

634

640

os.setsid()

635

641

if not nochdir:

636

642

os.chdir("/")

643

if os.fork():

644

sys.exit()

637

645

if not noclose:

638

646

# Close all standard open file descriptors

639

647

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

651

659

global main_loop_started

652

660

main_loop_started = False

653

661

654

parser = OptionParser()

662

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

655

663

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

656

664

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

657

665

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

660

668

help="Port number to receive requests on")

661

669

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

662

670

help="Run self-test")

663

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

671

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

664

672

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

665

673

" terminal")

666

674

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

691

699

# Parse config file for server-global settings

692

700

server_config = ConfigParser.SafeConfigParser(server_defaults)

693

701

del server_defaults

694

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

702

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

695

703

server_section = "server"

696

704

# Convert the SafeConfigParser object to a dict

697

705

server_settings = dict(server_config.items(server_section))

710

718

del options

711

719

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

712

720

721

debug = server_settings["debug"]

722

723

if not debug:

724

syslogger.setLevel(logging.WARNING)

725

console.setLevel(logging.WARNING)

726

727

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

728

syslogger.setFormatter(logging.Formatter\

729

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

730

' %%(message)s'

731

% server_settings["servicename"]))

732

713

733

# Parse config file with clients

714

734

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

715

735

"interval": "5m",

716

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

736

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

717

737

}

718

738

client_config = ConfigParser.SafeConfigParser(client_defaults)

719

739

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

737

757

avahi.DBUS_INTERFACE_SERVER )

738

758

# End of Avahi example code

739

759

740

debug = server_settings["debug"]

741

742

if debug:

743

console = logging.StreamHandler()

744

# console.setLevel(logging.DEBUG)

745

console.setFormatter(logging.Formatter\

746

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

747

logger.addHandler(console)

748

del console

749

750

760

clients = Set()

751

761

def remove_from_clients(client):

752

762

clients.remove(client)

753

763

if not clients:

754

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

764

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

755

765

sys.exit()

756

766

757

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

767

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

758

768

stop_hook = remove_from_clients,

759

**(dict(client_config\

760

.items(section))))

769

config

770

= dict(client_config.items(section)))

761

771

for section in client_config.sections()))

772

if not clients:

773

logger.critical(u"No clients defined")

774

sys.exit(1)

762

775

763

776

if not debug:

764

daemon(False, False)

777

logger.removeHandler(console)

778

daemon()

779

780

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

781

pid = os.getpid()

782

try:

783

pidfile = open(pidfilename, "w")

784

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

785

pidfile.close()

786

del pidfile

787

except IOError, err:

788

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

789

pidfilename, os.getpid())

765

790

766

791

def cleanup():

767

792

"Cleanup function; run on exit"

794

819

clients=clients)

795

820

# Find out what port we got

796

821

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

797

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

798

u" scope_id %d" % tcp_server.socket.getsockname())

822

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

823

u" scope_id %d" % tcp_server.socket.getsockname())

799

824

800

825

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

801

826

814

839

tcp_server.handle_request\

815

840

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

816

841

817

logger.debug("Starting main loop")

842

logger.debug(u"Starting main loop")

818

843

main_loop_started = True

819

844

main_loop.run()

820

845

except AvahiError, error: