/usr/share/pyshared/desktopcouch/application/pair/couchdb_pairing/dbus_io.py is in python-desktopcouch-application 1.0.8-0ubuntu3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#
# This file is part of desktopcouch.
#
# desktopcouch is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License version 3
# as published by the Free Software Foundation.
#
# desktopcouch 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with desktopcouch. If not, see <http://www.gnu.org/licenses/>.
#
# Authors: Chad Miller <chad.miller@canonical.com>
"""Communicate with DBUS and also the APIs it proxies, like Zeroconf."""
import logging
import dbus
import avahi
from desktopcouch.application.pair.couchdb_pairing import couchdb_io
INVITATIONS_DISCOVERY_SERVICE_TYPE = "_couchdb_pairing_invitations._tcp"
LOCATION_DISCOVERY_SERVICE_TYPE = "_couchdb_location._tcp"
DESKTOPCOUCH_DBUS_INTERFACE = "org.desktopcouch.CouchDB"
def get_local_hostname():
"""Get the name of this host, as Unicode host and domain parts."""
_, server = get_dbus_bus_server()
return server.GetHostName(), server.GetDomainName()
def get_remote_hostname(ip_address_as_ascii, iface=avahi.IF_UNSPEC):
"""Look up the name of a host by its address. This is like DNS
PTR in-arpa, but all zeroconf-y."""
_, server = get_dbus_bus_server()
try:
hostname = server.ResolveAddress(
iface, avahi.PROTO_UNSPEC, ip_address_as_ascii, dbus.UInt32(0))[4]
except dbus.exceptions.DBusException:
return ip_address_as_ascii
return hostname
def get_dbus_bus_server():
"""Common sequence of steps to get a Bus and Server object from DBUS."""
bus = dbus.SystemBus()
root_name = bus.get_object(avahi.DBUS_NAME, avahi.DBUS_PATH_SERVER)
server = dbus.Interface(root_name, avahi.DBUS_INTERFACE_SERVER)
return bus, server
class Advertisement(object):
"""Represents an advertised service that exists on this host."""
def __init__(self, port, name, stype="", domain="", host="", text=None):
if text is None:
text = {}
super(Advertisement, self).__init__()
self.logging = logging.getLogger(self.__class__.__name__)
self.name = name
self.stype = stype
self.domain = domain
self.host = host
self.port = int(port)
if hasattr(text, "keys"):
self.text = avahi.dict_to_txt_array(text)
else:
self.text = text
self.group = None
def publish(self):
"""Start the advertisement."""
bus, server = get_dbus_bus_server()
entry_group = bus.get_object(avahi.DBUS_NAME, server.EntryGroupNew())
g = dbus.Interface(entry_group, avahi.DBUS_INTERFACE_ENTRY_GROUP)
g.AddService(avahi.IF_UNSPEC, avahi.PROTO_UNSPEC, dbus.UInt32(0),
self.name, self.stype, self.domain, self.host,
dbus.UInt16(self.port), self.text)
g.Commit()
self.logging.info("starting advertising %s on port %d",
self.stype, self.port)
self.group = g
def unpublish(self):
"""End the advertisement."""
try:
self.logging.info("ending advertising %s on port %d",
self.stype, self.port)
self.group.Reset()
except dbus.DBusException:
self.logging.exception("Couldn't reset DBus at shutdown.")
self.group = None
def die(self):
"""Quit."""
self.unpublish()
class LocationAdvertisement(Advertisement):
"""An advertised couchdb location. See Advertisement class."""
def __init__(self, *args, **kwargs):
kwargs["stype"] = LOCATION_DISCOVERY_SERVICE_TYPE
super(LocationAdvertisement, self).__init__(*args, **kwargs)
class PairAdvertisement(Advertisement):
"""An advertised couchdb pairing opportunity. See Advertisement class."""
def __init__(self, *args, **kwargs):
kwargs["stype"] = INVITATIONS_DISCOVERY_SERVICE_TYPE
super(PairAdvertisement, self).__init__(*args, **kwargs)
def avahitext_to_dict(avahitext):
"""Turn avahi text into a dictionary."""
text = {}
for integers in avahitext:
try:
key, value = "".join(chr(i) for i in integers).split("=", 1)
text[key] = value
except ValueError:
logging.exception("k/v field could not be decoded.")
return text
# k=uuid, v=(addr, port)
nearby_desktop_couch_instances = dict() # pylint: disable=C0103
def cb_found_desktopcouch_server(uuid, host_address, port):
"""Check if nearby server is found."""
nearby_desktop_couch_instances[uuid] = (unicode(host_address), int(port))
def cb_lost_desktopcouch_server(uuid):
"""Check if nearby server is lost."""
try:
del nearby_desktop_couch_instances[uuid]
except KeyError:
pass
def get_seen_paired_hosts(uri=None):
"""Get the hosts that have been seen."""
pairing_encyclopedia = couchdb_io.get_all_known_pairings(uri=uri)
return (
(
uuid,
addr,
port,
not pairing_encyclopedia[uuid]["active"],
pairing_encyclopedia[uuid]["oauth"],
)
for uuid, (addr, port)
in nearby_desktop_couch_instances.items()
if uuid in pairing_encyclopedia)
def maintain_discovered_servers(add_cb=cb_found_desktopcouch_server,
del_cb=cb_lost_desktopcouch_server):
"""Maintain the discovered servers."""
# pylint: disable=W0613
def remove_item_handler(cb, interface, protocol, name, stype, domain,
flags):
"""A service disappeared."""
if name.startswith("desktopcouch "):
hostid = name[13:]
logging.debug("lost sight of %r", hostid)
cb(hostid)
else:
logging.error("annc doesn't look like one of ours. %r", name)
# pylint: enable=W0613
# pylint: disable=W0613
def new_item_handler(cb, interface, protocol, name, stype, domain, flags):
"""A service appeared."""
def handle_error(*args):
"""An error in resolving a new service."""
logging.error("zeroconf ItemNew error for services, %s", args)
def handle_resolved(cb, *args):
"""Successfully resolved a new service, which we decode and send
back to our calling environment with the callback function."""
name, host, port = args[2], args[5], args[8]
if name.startswith("desktopcouch "):
cb(name[13:], host, port)
else:
logging.error("annc doesn't look like one of ours. %r", name)
return True
server.ResolveService(interface, protocol, name, stype,
domain, avahi.PROTO_UNSPEC, dbus.UInt32(0),
reply_handler=lambda *a: handle_resolved(cb, *a),
error_handler=handle_error)
# pylint: enable=W0613
bus, server = get_dbus_bus_server()
domain_name = get_local_hostname()[1]
browser = server.ServiceBrowserNew(avahi.IF_UNSPEC, avahi.PROTO_UNSPEC,
LOCATION_DISCOVERY_SERVICE_TYPE, domain_name, dbus.UInt32(0))
browser_name = bus.get_object(avahi.DBUS_NAME, browser)
sbrowser = dbus.Interface(browser_name,
avahi.DBUS_INTERFACE_SERVICE_BROWSER)
sbrowser.connect_to_signal("ItemNew",
lambda *a: new_item_handler(add_cb, *a))
sbrowser.connect_to_signal("ItemRemove",
lambda *a: remove_item_handler(del_cb, *a))
sbrowser.connect_to_signal("Failure",
lambda *a: logging.error("avahi error %r", a))
def discover_services(add_commport_name_cb, del_commport_name_cb,
show_local=False):
"""Start looking for services. Use two callbacks to handle seeing
new services and seeing services disappear."""
# pylint: disable=W0613
def remove_item_handler(cb, interface, protocol, name, stype, domain,
flags):
"""A service disappeared."""
if not show_local and flags & avahi.LOOKUP_RESULT_LOCAL:
return
cb(name)
# pylint: enable=W0613
def new_item_handler(cb, interface, protocol, name, stype, domain, flags):
"""A service appeared."""
def handle_error(*args):
"""An error in resolving a new service."""
logging.error("zeroconf ItemNew error for services, %s", args)
def handle_resolved(cb, *args):
"""Successfully resolved a new service, which we decode and send
back to our calling environment with the callback function."""
text = avahitext_to_dict(args[9])
name, host, port = args[2], args[5], args[8]
cb(name, text.get("description", "?"),
host, port, text.get("version", None))
if not show_local and flags & avahi.LOOKUP_RESULT_LOCAL:
return
server.ResolveService(interface, protocol, name, stype,
domain, avahi.PROTO_UNSPEC, dbus.UInt32(0),
reply_handler=lambda *a: handle_resolved(cb, *a),
error_handler=handle_error)
bus, server = get_dbus_bus_server()
domain_name = get_local_hostname()[1]
browser = server.ServiceBrowserNew(avahi.IF_UNSPEC, avahi.PROTO_UNSPEC,
INVITATIONS_DISCOVERY_SERVICE_TYPE, domain_name, dbus.UInt32(0))
browser_name = bus.get_object(avahi.DBUS_NAME, browser)
sbrowser = dbus.Interface(browser_name,
avahi.DBUS_INTERFACE_SERVICE_BROWSER)
sbrowser.connect_to_signal("ItemNew",
lambda *a: new_item_handler(add_commport_name_cb, *a))
sbrowser.connect_to_signal("ItemRemove",
lambda *a: remove_item_handler(del_commport_name_cb, *a))
sbrowser.connect_to_signal("Failure",
lambda *a: logging.error("avahi error %r", a))
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