/mandos/trunk : revision 46

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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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logger = logging.Logger('mandos')

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syslogger = logging.handlers.SysLogHandler\

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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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self.interface = interface

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self.name = name

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self.type = type

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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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logger.error(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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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.fqdn = config.get("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(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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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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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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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.debug(u"Starting checker %r for %s",

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command, self.name)

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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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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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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()

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

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def handle(self):

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

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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()

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

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try:

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

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raise RuntimeError

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except (ValueError, IndexError, RuntimeError), error:

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

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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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try:

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session.handshake()

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except gnutls.errors.GNUTLSError, error:

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

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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.

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return

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try:

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fpr = fingerprint(peer_certificate(session))

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

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

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

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session.bye()

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return

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

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client = c

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break

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if not client:

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

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

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fpr)

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session.bye()

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return

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

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# that the client timed out while establishing the GnuTLS

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# session.

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if not client.still_valid():

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

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

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vars(client))

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session.bye()

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return

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sent_size = 0

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self.settings["interface"])

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except socket.error, error:

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if error[0] == errno.EPERM:

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logger.warning(u"No permission to"

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u" bind to interface %s",

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self.settings["interface"])

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logger.error(u"No permission to"

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u" bind to interface %s",

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self.settings["interface"])

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else:

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raise error

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

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def server_state_changed(state):

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

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if state == avahi.SERVER_COLLISION:

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logger.warning(u"Server name collision")

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logger.error(u"Server name collision")

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service.remove()

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elif state == avahi.SERVER_RUNNING:

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service.add()

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unicode(error))

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

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

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def if_nametoindex(interface):

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

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if _func[0] is not None:

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return _func[0](interface)

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global if_nametoindex

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try:

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

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import ctypes.util

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while True:

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try:

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libc = ctypes.cdll.LoadLibrary\

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

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_func[0] = libc.if_nametoindex

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return _func[0](interface)

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except IOError, e:

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if e != errno.EINTR:

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raise

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if_nametoindex = ctypes.cdll.LoadLibrary\

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

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except (OSError, AttributeError):

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if "struct" not in sys.modules:

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import struct

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if "fcntl" not in sys.modules:

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import fcntl

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def the_hard_way(interface):

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def if_nametoindex(interface):

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

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

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s = socket.socket()

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s.close()

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

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return interface_index

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_func[0] = the_hard_way

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return _func[0](interface)

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return if_nametoindex(interface)

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def daemon(nochdir, noclose):

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os.setsid()

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if not nochdir:

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os.chdir("/")

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if os.fork():

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sys.exit()

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if not noclose:

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# Close all standard open file descriptors

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

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def remove_from_clients(client):

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clients.remove(client)

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if not clients:

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

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

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sys.exit()

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

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

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stop_hook = remove_from_clients,

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**(dict(client_config\

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.items(section))))

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config

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= dict(client_config.items(section)))

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for section in client_config.sections()))

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if not debug:

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clients=clients)

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# Find out what port we got

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

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

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

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

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

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

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