sugar-toolkit-gtk3/services/presence/PresenceService.py

# Copyright (C) 2006, Red Hat, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

import avahi, dbus, dbus.glib, gobject
import Buddy
import Service
import Activity
import random
import logging
from sugar import util
from sugar import env
from sugar import profile
import BuddyIconCache


_SA_UNRESOLVED = 0
_SA_RESOLVE_PENDING = 1
_SA_RESOLVED = 2
class ServiceAdv(object):
	"""Wrapper class to track services from Avahi."""
	def __init__(self, interface, protocol, name, stype, domain, local):
		self._interface = interface
		self._protocol = protocol
		if not isinstance(name, unicode):
			raise ValueError("service advertisement name must be unicode.")
		self._name = name
		if not isinstance(stype, unicode):
			raise ValueError("service advertisement type must be unicode.")
		self._stype = stype
		if not isinstance(domain, unicode):
			raise ValueError("service advertisement domain must be unicode.")
		self._domain = domain
		self._service = None
		if not isinstance(local, bool):
			raise ValueError("local must be a bool.")
		self._local = local
		self._state = _SA_UNRESOLVED
		self._resolver = None

	def __del__(self):
		if self._resolver:
			del self._resolver

	def interface(self):
		return self._interface
	def protocol(self):
		return self._protocol
	def name(self):
		return self._name
	def stype(self):
		return self._stype
	def domain(self):
		return self._domain
	def is_local(self):
		return self._local
	def service(self):
		return self._service
	def set_service(self, service):
		if not isinstance(service, Service.Service):
			raise ValueError("must be a valid service.")
		if service != self._service:
			self._service = service
	def resolver(self):
		return self._resolver
	def set_resolver(self, resolver):
		if not isinstance(resolver, dbus.Interface):
			raise ValueError("must be a valid dbus object")
		self._resolver = resolver
	def state(self):
		return self._state
	def set_state(self, state):
		if state == _SA_RESOLVE_PENDING:
			if self._state == _SA_RESOLVED:
				raise ValueError("Can't reset to resolve pending from resolved.")
		self._state = state

class RegisteredServiceType(object):
	def __init__(self, stype):
		self._stype = stype
		self._refcount = 1

	def get_type(self):
		return self._stype

	def ref(self):
		self._refcount += 1

	def unref(self):
		self._refcount -= 1
		return self._refcount

def _txt_to_dict(txt):
	"""Convert an avahi-returned TXT record formatted
	as nested arrays of integers (from dbus) into a dict
	of key/value string pairs."""
	prop_dict = {}
	props = avahi.txt_array_to_string_array(txt)
	for item in props:
		key = value = None
		if '=' not in item:
			# No = means a boolean value of true
			key = item
			value = True
		else:
			(key, value) = item.split('=')
		prop_dict[key] = value
	return prop_dict


_PRESENCE_SERVICE = "org.laptop.Presence"
_PRESENCE_DBUS_INTERFACE = "org.laptop.Presence"
_PRESENCE_OBJECT_PATH = "/org/laptop/Presence"

class NotFoundError(Exception):
	pass

class PresenceServiceDBusHelper(dbus.service.Object):
	def __init__(self, parent, bus_name):
		self._parent = parent
		self._bus_name = bus_name
		dbus.service.Object.__init__(self, bus_name, _PRESENCE_OBJECT_PATH)

	@dbus.service.signal(_PRESENCE_DBUS_INTERFACE,
						signature="o")
	def BuddyAppeared(self, object_path):
		pass

	@dbus.service.signal(_PRESENCE_DBUS_INTERFACE,
						signature="o")
	def BuddyDisappeared(self, object_path):
		pass

	@dbus.service.signal(_PRESENCE_DBUS_INTERFACE,
						signature="o")
	def ServiceAppeared(self, object_path):
		pass

	@dbus.service.signal(_PRESENCE_DBUS_INTERFACE,
						signature="o")
	def ServiceDisappeared(self, object_path):
		pass

	@dbus.service.signal(_PRESENCE_DBUS_INTERFACE,
						signature="o")
	def ActivityAppeared(self, object_path):
		pass

	@dbus.service.signal(_PRESENCE_DBUS_INTERFACE,
						signature="o")
	def ActivityDisappeared(self, object_path):
		pass

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="", out_signature="ao")
	def getServices(self):
		ret = []
		for serv in self._parent.get_services():
			ret.append(serv.object_path())
		return ret

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="s", out_signature="ao")
	def getServicesOfType(self, stype):
		ret = []
		for serv in self._parent.get_services_of_type(stype):
			ret.append(serv.object_path())
		return ret

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="", out_signature="ao")
	def getActivities(self):
		ret = []
		for act in self._parent.get_activities():
			ret.append(act.object_path())
		return ret

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="s", out_signature="o")
	def getActivity(self, actid):
		act = self._parent.get_activity(actid)
		if not act:
			raise NotFoundError("Not found")
		return act.object_path()

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="", out_signature="ao")
	def getBuddies(self):
		ret = []
		for buddy in self._parent.get_buddies():
			ret.append(buddy.object_path())
		return ret

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="s", out_signature="o")
	def getBuddyByName(self, name):
		buddy = self._parent.get_buddy_by_name(name)
		if not buddy:
			raise NotFoundError("Not found")
		return buddy.object_path()

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="s", out_signature="o")
	def getBuddyByAddress(self, addr):
		buddy = self._parent.get_buddy_by_address(addr)
		if not buddy:
			raise NotFoundError("Not found")
		return buddy.object_path()

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="", out_signature="o")
	def getOwner(self):
		owner = self._parent.get_owner()
		if not owner:
			raise NotFoundError("Not found")
		return owner.object_path()

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="os", out_signature="o",
						sender_keyword="sender")
	def joinActivity(self, activity_op, stype, sender):
		found_activity = None
		acts = self._parent.get_activities()
		for act in acts:
			if act.object_path() == activity_op:
				found_activity = act
				break
		if not found_activity:
			raise NotFoundError("The activity %s was not found." % activity_op)
		return self._parent.join_activity(found_activity, stype, sender)

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="ssa{ss}sis", out_signature="o",
						sender_keyword="sender")
	def shareActivity(self, activity_id, stype, properties, address, port,
			domain, sender=None):
		if not len(address):
			address = None
		service = self._parent.share_activity(activity_id, stype, properties, address,
				port, domain, sender)
		return service.object_path()

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="ssa{ss}sis", out_signature="o",
						sender_keyword="sender")
	def registerService(self, name, stype, properties, address, port, domain,
			sender=None):
		if not len(address):
			address = None
		service = self._parent.register_service(name, stype, properties, address,
				port, domain, sender)
		return service.object_path()

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="o", out_signature="",
						sender_keyword="sender")
	def unregisterService(self, service_op, sender):
		found_serv = None
		services = self._parent.get_services()
		for serv in services:
			if serv.object_path() == service_op:
				found_serv = serv
				break
		if not found_serv:
			raise NotFoundError("The service %s was not found." % service_op)
		return self._parent.unregister_service(found_serv, sender)

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="s", out_signature="")
	def registerServiceType(self, stype):
		self._parent.register_service_type(stype)

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE,
						in_signature="s", out_signature="")
	def unregisterServiceType(self, stype):
		self._parent.unregister_service_type(stype)

	@dbus.service.method(_PRESENCE_DBUS_INTERFACE)
	def start(self):
		self._parent.start()

class PresenceService(object):
	def __init__(self):
		# interface -> IP address: interfaces we've gotten events on so far
		self._started = False
		self._local_addrs = {}

		self._next_object_id = 0

		self._buddies = {} 		# nick -> Buddy
		self._services = {}		# (name, type) -> Service
		self._activities = {}	# activity id -> Activity

		# Keep track of stuff we're already browsing
		self._service_type_browsers = {}
		self._service_browsers = {}

		# Resolved service list
		self._service_advs = []

		# Service types we care about resolving
		self._registered_service_types = []

		# Set up the dbus service we provide
		self._session_bus = dbus.SessionBus()
		self._bus_name = dbus.service.BusName(_PRESENCE_SERVICE, bus=self._session_bus)		
		self._dbus_helper = PresenceServiceDBusHelper(self, self._bus_name)

		self._icon_cache = BuddyIconCache.BuddyIconCache()

		# Our owner object
		if profile.get_nick_name():
			objid = self._get_next_object_id()
			self._owner = Buddy.Owner(self, self._bus_name,
									  objid, self._icon_cache)
			self._buddies[self._owner.get_name()] = self._owner
		else:
			self._owner = None

	def start(self):
		if self._started:
			return
		self._started = True

		# Connect to Avahi for mDNS stuff
		self._system_bus = dbus.SystemBus()
		self._mdns_service = dbus.Interface(self._system_bus.get_object(avahi.DBUS_NAME,
				avahi.DBUS_PATH_SERVER), avahi.DBUS_INTERFACE_SERVER)

		# Always browse .local
		self._new_domain_cb(avahi.IF_UNSPEC, avahi.PROTO_UNSPEC, "local")

		# Connect to Avahi and start looking for stuff
		domain_browser = self._mdns_service.DomainBrowserNew(avahi.IF_UNSPEC, avahi.PROTO_UNSPEC,
						"", avahi.DOMAIN_BROWSER_BROWSE, dbus.UInt32(0))
		db = dbus.Interface(self._system_bus.get_object(avahi.DBUS_NAME, domain_browser), avahi.DBUS_INTERFACE_DOMAIN_BROWSER)
		db.connect_to_signal('ItemNew', self._new_domain_cb_glue)

	def _get_next_object_id(self):
		"""Increment and return the object ID counter."""
		self._next_object_id = self._next_object_id + 1
		return self._next_object_id

	def get_services(self):
		return self._services.values()

	def get_services_of_type(self, stype):
		ret = []
		for serv in self._services.values():
			if serv.get_type() == stype:
				ret.append(serv)
		return ret

	def get_activities(self):
		# Only return valid activities
		ret = []
		for act in self._activities.values():
			if act.is_valid():
				ret.append(act)
		return ret

	def get_activity(self, actid):
		if self._activities.has_key(actid):
			act = self._activities[actid]
			if act.is_valid():
				return act
		return None

	def get_buddies(self):
		buddies = []
		for buddy in self._buddies.values():
			if buddy.is_valid():
				buddies.append(buddy)
		return buddies

	def get_buddy_by_name(self, name):
		if self._buddies.has_key(name):
			if self._buddies[name].is_valid():
				return self._buddies[name]
		return None

	def get_buddy_by_address(self, address):
		for buddy in self._buddies.values():
			if buddy.get_address() == address and buddy.is_valid():
				return buddy
		return None

	def get_owner(self):
		return self._owner

	def _find_service_adv(self, interface=None, protocol=None, name=None,
			stype=None, domain=None, local=None):
		"""Search a list of service advertisements for ones matching
		certain criteria."""
		adv_list = []
		for adv in self._service_advs:
			if interface and adv.interface() != interface:
				continue
			if protocol and adv.protocol() != protocol:
				continue
			if name and adv.name() != name:
				continue
			if stype and adv.stype() != stype:
				continue
			if domain and adv.domain() != domain:
				continue
			if local is not None and adv.is_local() != local:
				continue
			adv_list.append(adv)
		return adv_list

	def _find_registered_service_type(self, stype):
		for item in self._registered_service_types:
			if item.get_type() == stype:
				return item
		return None

	def _handle_new_service_for_buddy(self, service, local):
		"""Deal with a new discovered service object."""
		# Once a service is resolved, we match it up to an existing buddy,
		# or create a new Buddy if this is the first service known about the buddy
		buddy_was_valid = False
		name = service.get_name()
		buddy = None
		try:
			buddy = self._buddies[name]
			buddy_was_valid = buddy.is_valid()
			service_added = buddy.add_service(service)
			if service_added:
				self._dbus_helper.ServiceAppeared(service.object_path())
		except KeyError:
			source_addr = service.get_source_address()
			objid = self._get_next_object_id()
			buddy = Buddy.Buddy(self._bus_name, objid, service, self._icon_cache)
			self._buddies[name] = buddy
			self._dbus_helper.ServiceAppeared(service.object_path())
		if not buddy_was_valid and buddy.is_valid():
			self._dbus_helper.BuddyAppeared(buddy.object_path())
		return buddy

	def _handle_new_activity_service(self, service):
		# If the serivce is an activity service, merge it into our activities list
		actid = service.get_activity_id()
		if not actid:
			return
		activity = None
		was_valid = False
		if not self._activities.has_key(actid):
			objid = self._get_next_object_id()
			activity = Activity.Activity(self._bus_name, objid, service)
			self._activities[actid] = activity
		else:
			activity = self._activities[actid]
			was_valid = activity.is_valid()

		if activity:
			activity.add_service(service)

			# Add the activity to its buddy
			# FIXME: use something other than name to attribute to buddy
			try:
				buddy = self._buddies[service.get_name()]
				buddy.add_activity(activity)
			except KeyError:
				pass		

		if not was_valid and activity.is_valid():
			self._dbus_helper.ActivityAppeared(activity.object_path())

	def _handle_remove_activity_service(self, service):
		actid = service.get_activity_id()
		if not actid:
			return
		if not self._activities.has_key(actid):
			return

		activity = self._activities[actid]

		activity.remove_service(service)
		if len(activity.get_services()) == 0:
			# Remove the activity from its buddy
			# FIXME: use something other than name to attribute to buddy
			try:
				buddy = self._buddies[service.get_name()]
				buddy.remove_activity(activity)
			except KeyError:
				pass		

			# Kill the activity
			self._dbus_helper.ActivityDisappeared(activity.object_path())
			del self._activities[actid]

	def _service_resolved_cb(self, adv, interface, protocol, full_name,
			stype, domain, host, aprotocol, address, port, txt, flags,
			updated):
		"""When the service discovery finally gets here, we've got enough
		information about the service to assign it to a buddy."""
		if updated == False:
			logging.debug("Resolved service '%s' type '%s' domain '%s' to " \
					" %s:%s" % (full_name, stype, domain, address, port))

		if not adv in self._service_advs:
			return False
		if adv.state() != _SA_RESOLVED:
			return False

		# See if we know about this service already
		service = None
		key = (full_name, stype)
		props = _txt_to_dict(txt)
		if not self._services.has_key(key):
			objid = self._get_next_object_id()
			service = Service.Service(self._bus_name, objid, name=full_name,
					stype=stype, domain=domain, address=address, port=port,
					properties=props, source_address=address)
			self._services[key] = service
		else:
			# Already tracking this service; either:
			# a) we were the one that shared it in the first place,
			#     and therefore the source address would not have
			#     been set yet
			# b) the service has been updated
			service = self._services[key]
			if not service.get_source_address():
				service.set_source_address(address)
			if not service.get_address():
				service.set_address(address)

		adv.set_service(service)

		if service and updated:
			service.set_properties(props, from_network=True)
			return False

		# Merge the service into our buddy and activity lists, if needed
		buddy = self._handle_new_service_for_buddy(service, adv.is_local())
		if buddy and service.get_activity_id():
			self._handle_new_activity_service(service)

		return False

	def _service_resolved_cb_glue(self, adv, interface, protocol, name,
			stype, domain, host, aprotocol, address, port, txt, flags):
		# Avahi doesn't flag updates to existing services, so we have
		# to determine that here
		updated = False
		if adv.state() == _SA_RESOLVED:
			updated = True

		adv.set_state(_SA_RESOLVED)
		gobject.idle_add(self._service_resolved_cb, adv, interface,
				protocol, name, stype, domain, host, aprotocol, address,
				port, txt, flags, updated)

	def _service_resolved_failure_cb(self, adv, err):
		adv.set_state(_SA_UNRESOLVED)
		logging.error("Error resolving service %s.%s: %s" % (adv.name(), adv.stype(), err))

	def _resolve_service(self, adv):
		"""Resolve and lookup a ZeroConf service to obtain its address and TXT records."""
		# Ask avahi to resolve this particular service
		path = self._mdns_service.ServiceResolverNew(dbus.Int32(adv.interface()),
				dbus.Int32(adv.protocol()), adv.name(), adv.stype(), adv.domain(),
				avahi.PROTO_UNSPEC, dbus.UInt32(0))
		resolver = dbus.Interface(self._system_bus.get_object(avahi.DBUS_NAME, path),
							avahi.DBUS_INTERFACE_SERVICE_RESOLVER)
		resolver.connect_to_signal('Found', lambda *args: self._service_resolved_cb_glue(adv, *args))
		resolver.connect_to_signal('Failure', lambda *args: self._service_resolved_failure_cb(adv, *args))
		adv.set_resolver(resolver)
		return False

	def _service_appeared_cb(self, interface, protocol, full_name, stype, domain, flags):
		local = flags & avahi.LOOKUP_RESULT_OUR_OWN > 0
		adv_list = self._find_service_adv(interface=interface, protocol=protocol,
				name=full_name, stype=stype, domain=domain, local=local)
		adv = None
		if not adv_list:
			adv = ServiceAdv(interface=interface, protocol=protocol, name=full_name,
					stype=stype, domain=domain, local=local)
			self._service_advs.append(adv)
		else:
			adv = adv_list[0]

		# Decompose service name if we can
		(actid, buddy_name) = Service.decompose_service_name(full_name)

		# If we care about the service right now, resolve it
		resolve = False
		item = self._find_registered_service_type(stype)
		if actid is not None or item is not None:
			resolve = True
		if resolve and adv.state() == _SA_UNRESOLVED:
			logging.debug("Found '%s' (%d) of type '%s' in domain" \
					" '%s' on %i.%i; will resolve." % (full_name, flags, stype,
					domain, interface, protocol))
			adv.set_state(_SA_RESOLVE_PENDING)
			gobject.idle_add(self._resolve_service, adv)
			
		return False

	def _service_appeared_cb_glue(self, interface, protocol, name, stype, domain, flags):
		gobject.idle_add(self._service_appeared_cb, interface, protocol, name, stype, domain, flags)

	def _service_disappeared_cb(self, interface, protocol, full_name, stype, domain, flags):
		local = flags & avahi.LOOKUP_RESULT_OUR_OWN > 0
		# If it's an unresolved service, remove it from our unresolved list
		adv_list = self._find_service_adv(interface=interface, protocol=protocol,
				name=full_name, stype=stype, domain=domain, local=local)
		if not adv_list:
			return False

		# Get the service object; if none, we have nothing left to do
		adv = adv_list[0]
		service = adv.service()
		self._service_advs.remove(adv)
		del adv
		if not service:
			return False

		logging.debug("Service %s.%s in domain %s on %i.%i disappeared." % (full_name,
				stype, domain, interface, protocol))

		self._dbus_helper.ServiceDisappeared(service.object_path())
		self._handle_remove_activity_service(service)

		# Decompose service name if we can
		(actid, buddy_name) = Service.decompose_service_name(full_name)

		# Remove the service from the buddy
		try:
			buddy = self._buddies[buddy_name]
		except KeyError:
			pass
		else:
			buddy.remove_service(service)
			if not buddy.is_valid():
				self._dbus_helper.BuddyDisappeared(buddy.object_path())
				del self._buddies[buddy_name]
		key = (service.get_full_name(), service.get_type())
		del self._services[key]
		return False

	def _service_disappeared_cb_glue(self, interface, protocol, name, stype, domain, flags):
		gobject.idle_add(self._service_disappeared_cb, interface, protocol, name, stype, domain, flags)

	def _new_service_type_cb(self, interface, protocol, stype, domain, flags):
		# Are we already browsing this domain for this type? 
		if self._service_browsers.has_key((interface, protocol, stype, domain)):
			return

		# Start browsing for all services of this type in this domain
		try:
			s_browser = self._mdns_service.ServiceBrowserNew(interface,
					protocol, stype, domain, dbus.UInt32(0))
			browser_obj = dbus.Interface(self._system_bus.get_object(avahi.DBUS_NAME, s_browser),
							avahi.DBUS_INTERFACE_SERVICE_BROWSER)
			browser_obj.connect_to_signal('ItemNew', self._service_appeared_cb_glue)
			browser_obj.connect_to_signal('ItemRemove', self._service_disappeared_cb_glue)

			self._service_browsers[(interface, protocol, stype, domain)] = browser_obj
		except dbus.DBusException:
			logging.debug("Error browsing service type '%s'" % stype)
		return False

	def _new_service_type_cb_glue(self, interface, protocol, stype, domain, flags):
		if len(stype) > 0:
			gobject.idle_add(self._new_service_type_cb, interface, protocol,
					stype, domain, flags)

	def _new_domain_cb(self, interface, protocol, domain, flags=0):
		"""Callback from Avahi when a new domain has been found.  Start
		browsing the new domain."""
		# Only use .local for now...
		if domain != "local":
			return

		# Are we already browsing this domain?
		if self._service_type_browsers.has_key((interface, protocol, domain)):
			return

		# Start browsing this domain for the services its members offer
		try:
			st_browser = self._mdns_service.ServiceTypeBrowserNew(interface, protocol, domain, dbus.UInt32(0))
			browser_obj = dbus.Interface(self._system_bus.get_object(avahi.DBUS_NAME, st_browser),
							avahi.DBUS_INTERFACE_SERVICE_TYPE_BROWSER)
		except dbus.DBusException, exc:
			str_exc = str(exc)
			logging.error("got exception %s while attempting to browse domain %s on %i.%i" % (str_exc, domain, interface, protocol))
			if str_exc.find("The name org.freedesktop.Avahi was not provided by any .service files") >= 0:
				raise Exception("Avahi does not appear to be running.  '%s'" % str_exc)
			else:
				raise exc
		logging.debug("Browsing domain '%s' on %i.%i ..." % (domain, interface, protocol))
		browser_obj.connect_to_signal('ItemNew', self._new_service_type_cb_glue)
		self._service_type_browsers[(interface, protocol, domain)] = browser_obj
		return False

	def _new_domain_cb_glue(self, interface, protocol, domain, flags=0):
		gobject.idle_add(self._new_domain_cb, interface, protocol, domain, flags)

	def join_activity(self, activity, stype, sender):
		services = activity.get_services_of_type(stype)
		if not len(services):
			raise NotFoundError("The service type %s was not present within " \
					"the activity %s" % (stype, activity.object_path()))
		act_service = services[0]
		props = act_service.get_properties()
		color = activity.get_color()
		if color:
			props['color'] = color
		return self._share_activity(activity.get_id(), stype, properties,
				act_service.get_address(), act_service.get_port(),
				act_service.get_domain(), sender)

	def share_activity(self, activity_id, stype, properties=None, address=None,
			port=-1, domain=u"local", sender=None):
		"""Convenience function to share an activity with other buddies."""
		if not util.validate_activity_id(activity_id):
			raise ValueError("invalid activity id")
		owner_nick = self._owner.get_name()
		real_name = Service.compose_service_name(owner_nick, activity_id)
		if address and not isinstance(address, unicode):
			raise ValueError("address must be a unicode string.")
		if address == None and stype.endswith('_udp'):
			# Use random currently unassigned multicast address
			address = u"232.%d.%d.%d" % (random.randint(0, 254), random.randint(1, 254),
					random.randint(1, 254))
			properties['address'] = address
			properties['port'] = port
		if port and port != -1 and (not isinstance(port, int) or port <= 1024 or port >= 65535):
			raise ValueError("port must be a number between 1024 and 65535")
		
		color = self._owner.get_color()
		if color:
			properties['color'] = color

		logging.debug('Share activity %s, type %s, address %s, port %d, " \
				"properties %s' % (activity_id, stype, address, port,
				properties))
		return self.register_service(real_name, stype, properties, address,
				port, domain, sender)

	def register_service(self, name, stype, properties={}, address=None,
			port=-1, domain=u"local", sender=None):
		"""Register a new service, advertising it to other Buddies on the network."""
		# Refuse to register if we can't get the dbus connection this request
		# came from for some reason
		if not sender:
			raise RuntimeError("Service registration request must have a sender.")

		(actid, person_name) = Service.decompose_service_name(name)
		if self.get_owner() and person_name != self.get_owner().get_name():
			raise RuntimeError("Tried to register a service that didn't have" \
					" Owner nick as the service name!")
		if not domain or not len(domain):
			domain = u"local"
		if not port or port == -1:
			port = random.randint(4000, 65000)

		objid = self._get_next_object_id()
		service = Service.Service(self._bus_name, objid, name=name,
				stype=stype, domain=domain, address=address, port=port,
				properties=properties, source_address=None,
				local_publisher=sender)
		self._services[(name, stype)] = service
		self.register_service_type(stype)
		service.register(self._system_bus, self._mdns_service)		
		return service

	def unregister_service(self, service, sender=None):
		service.unregister(sender)

	def register_service_type(self, stype):
		"""Requests that the Presence service look for and recognize
		a certain mDNS service types."""
		if not isinstance(stype, unicode):
			raise ValueError("service type must be a unicode string.")

		# If we've already registered it as a service type, ref it and return
		item = self._find_registered_service_type(stype)
		if item is not None:
			item.ref()
			return

		# Otherwise track this type now
		obj = RegisteredServiceType(stype)
		self._registered_service_types.append(obj)

		# Find unresolved services that match the service type
		# we're now interested in, and resolve them
		resolv_list = []

		# Find services of this type
		resolv_list = self._find_service_adv(stype=stype)
		# Request resolution for them if they aren't in-process already
		for adv in resolv_list:
			if adv.state() == _SA_UNRESOLVED:
				adv.set_state(_SA_RESOLVE_PENDING)
				gobject.idle_add(self._resolve_service, adv)

	def unregister_service_type(self, stype):
		"""Stop tracking a certain mDNS service."""
		if not isinstance(stype, unicode):
			raise ValueError("service type must be a unicode string.")

		# if it was found, unref it and possibly remove it
		item = self._find_registered_service_type(stype)
		if not item:
			return
		if item.unref() <= 0:
			self._registered_service_types.remove(item)
			del item


def main():
	from sugar import TracebackUtils
	loop = gobject.MainLoop()
	ps = PresenceService()
	tbh = TracebackUtils.TracebackHelper()
	try:
		loop.run()
	except KeyboardInterrupt:
		print 'Ctrl+C pressed, exiting...'

	del tbh


if __name__ == "__main__":
	main()