import enum
import json
from typing import Set, Dict, Optional, Iterable, Callable, Union
from gi.repository import GLib # type: ignore
from pydbus import SessionBus, SystemBus
from pydbus.bus import Bus
from defusedxml import ElementTree
from platypush.context import get_bus
from platypush.message import Message
from platypush.message.event import Event
from platypush.message.event.dbus import DbusSignalEvent
from platypush.message.request import Request
from platypush.plugins import RunnablePlugin, action
from platypush.schemas.dbus import DbusSignalSchema
from platypush.utils import run
_default_service_name = 'org.platypush.Bus'
_default_service_path = '/'
_default_interface_name = 'org.platypush.Bus'
class BusType(enum.Enum):
SYSTEM = 'system'
SESSION = 'session'
class DBusService():
"""
<node>
<interface name="org.platypush.Bus">
<method name="Post">
<arg type="s" name="msg" direction="in"/>
<arg type="s" name="response" direction="out"/>
</method>
</interface>
</node>
"""
@classmethod
def _parse_msg(cls, msg: Union[str, dict]) -> dict:
return Message.build(json.loads(json.dumps(msg)))
def Post(self, msg: dict):
"""
This method accepts a message as a JSON object
(either representing a valid request or an event) and either
executes it (request) or forwards it to the application bus (event).
:param msg: Request or event, as a dictionary.
:return: The return value of the request, or 0 if the message is an event.
"""
msg = self._parse_msg(msg)
if isinstance(msg, Request):
ret = run(msg.action, **msg.args)
if ret is None:
ret = '' # DBus doesn't like None return types
return ret
if isinstance(msg, Event):
get_bus().post(msg)
return 0
[docs]class DbusPlugin(RunnablePlugin):
"""
Plugin to interact with DBus.
This plugin can be used for the following tasks:
* It can expose a D-Bus interface that other applications can use to push messages
to Platypush (either action requests or events) serialized in JSON format.
You can disable this listener by setting ``service_name`` to ``null`` in your
configuration. If the D-Bus Platypush interface is enabled then you can push
Platypush events and requests in JSON format from another application or script
by specifying:
* The D-Bus service (default: ``org.platypush.Bus``)
* The D-Bus interface (default: ``org.platypush.Bus``)
* The D-Bus path (default: ``/``)
* The D-Bus method (``Post``)
* The Platypush JSON payload (first argument of the request). Format:
``{"type": "request", "action": "module.action", "args": {...}}``
* It can subscribe to multiple D-Bus signals, and it triggers a ``DbusSignalEvent``
when an event is received (signal filters should be specified in the ``signals``
configuration).
* It can be used to query and inspect D-Bus objects through the :meth:`.query` method.
* It can be used to execute methods exponsed by D-Bus objects through the
:meth:`.execute` method.
Requires:
* **pydbus** (``pip install pydbus``)
* **defusedxml** (``pip install defusedxml``)
Triggers:
* :class:`platypush.message.event.dbus.DbusSignalEvent` when a signal is received.
"""
[docs] def __init__(
self, signals: Optional[Iterable[dict]] = None,
service_name: Optional[str] = _default_service_name,
service_path: Optional[str] = _default_service_path, **kwargs
):
"""
:param signals: Specify this if you want to subscribe to specific DBus
signals. Structure:
.. schema:: dbus.DbusSignalSchema(many=True)
For example, to subscribe to all the messages on the session bus:
.. code-block:: yaml
dbus:
signals:
- bus: session
:param service_name: Name of the D-Bus service where Platypush will listen
for new messages (requests and events). Set to null if you want to disable
message execution over D-Bus for Platypush (default: ``org.platypush.Bus``).
:param service_path: The path of the D-Bus message listener. Set to null
if you want to disable message execution over D-Bus for Platypush
(default: ``/``).
"""
super().__init__(**kwargs)
self._system_bus = SystemBus()
self._session_bus = SessionBus()
self._loop = None
self._signals = DbusSignalSchema().load(signals or [], many=True)
self._signal_handlers = [
self._get_signal_handler(**signal)
for signal in self._signals
]
self.service_name = service_name
self.service_path = service_path
@staticmethod
def _get_signal_handler(bus: str, **_) -> Callable:
def handler(sender, path, interface, signal, params):
get_bus().post(
DbusSignalEvent(
bus=bus, signal=signal, path=path,
interface=interface, sender=sender, params=params
)
)
return handler
def _get_bus(self, bus_type: Union[str, BusType]) -> Bus:
if isinstance(bus_type, str):
bus_type = BusType(bus_type.lower())
return self._system_bus if bus_type == BusType.SYSTEM else self._session_bus
def _init_signal_listeners(self):
for i, signal in enumerate(self._signals):
handler = self._signal_handlers[i]
bus = self._get_bus(signal['bus'])
bus.subscribe(
signal_fired=handler,
signal=signal.get('signal'),
sender=signal.get('sender'),
object=signal.get('path'),
iface=signal.get('interface'),
)
def _init_service(self):
if not (self.service_name and self.service_path):
return
self._session_bus.publish(
self.service_name,
('/', DBusService()),
)
[docs] def main(self):
self._init_signal_listeners()
self._init_service()
self._loop = GLib.MainLoop()
self._loop.run()
[docs] def stop(self):
self._should_stop.set()
if self._loop:
self._loop.quit()
self._loop = None
self.logger.info('Stopped D-Bus main loop')
@staticmethod
def _get_bus_names(bus: Bus) -> Set[str]:
return {str(name) for name in bus.dbus.ListNames() if not name.startswith(':')}
def path_names(self, bus: Bus, service: str, object_path='/', paths=None, service_dict=None):
if paths is None:
paths = {}
if service_dict is None:
service_dict = {}
paths[object_path] = {}
try:
obj = bus.get(service, object_path)
interface = obj['org.freedesktop.DBus.Introspectable']
except GLib.GError as e:
self.logger.warning(f'Could not inspect D-Bus object {service}, path={object_path}: {e}')
return {}
except KeyError as e:
self.logger.warning(f'Could not get interfaces on the D-Bus object {service}, path={object_path}: {e}')
return {}
xml_string = interface.Introspect()
root = ElementTree.fromstring(xml_string)
for child in root:
if child.tag == 'node':
if object_path == '/':
object_path = ''
new_path = '/'.join((object_path, child.attrib['name']))
self.path_names(bus, service, new_path, paths, service_dict=service_dict)
else:
if not object_path:
object_path = '/'
functions_dict = {}
for func in list(child):
function_dict = {'name': func.attrib['name']}
for arg in list(func):
if arg.tag != 'arg':
continue
function_dict['args'] = function_dict.get('args', [])
function_dict['args'].append(arg.attrib)
if func.tag not in functions_dict:
functions_dict[func.tag] = []
functions_dict[func.tag].append(function_dict)
if functions_dict:
paths[object_path][child.attrib['name']] = functions_dict
if paths:
service_dict[service] = paths
return service_dict
[docs] @action
def query(self, service: Optional[str] = None, bus=tuple(t.value for t in BusType)) \
-> Dict[str, dict]:
"""
Query DBus for a specific service or for the full list of services.
:param service: Service name (default: None, query all services).
:param bus: Which bus(ses) should be queried (default: both ``system`` and ``session``).
:return: A ``{service_name -> {properties}}`` mapping. Example:
.. code-block:: json
"session": {
"org.platypush.Bus": {
"/": {
"org.freedesktop.DBus.Properties": {
"method": [
{
"name": "Get",
"args": [
{
"type": "s",
"name": "interface_name",
"direction": "in"
},
{
"type": "s",
"name": "property_name",
"direction": "in"
},
{
"type": "v",
"name": "value",
"direction": "out"
}
]
},
{
"name": "GetAll",
"args": [
{
"type": "s",
"name": "interface_name",
"direction": "in"
},
{
"type": "a{sv}",
"name": "properties",
"direction": "out"
}
]
},
{
"name": "Set",
"args": [
{
"type": "s",
"name": "interface_name",
"direction": "in"
},
{
"type": "s",
"name": "property_name",
"direction": "in"
},
{
"type": "v",
"name": "value",
"direction": "in"
}
]
}
],
"signal": [
{
"name": "PropertiesChanged",
"args": [
{
"type": "s",
"name": "interface_name"
},
{
"type": "a{sv}",
"name": "changed_properties"
},
{
"type": "as",
"name": "invalidated_properties"
}
]
}
]
},
"org.freedesktop.DBus.Introspectable": {
"method": [
{
"name": "Introspect",
"args": [
{
"type": "s",
"name": "xml_data",
"direction": "out"
}
]
}
]
},
"org.freedesktop.DBus.Peer": {
"method": [
{
"name": "Ping"
},
{
"name": "GetMachineId",
"args": [
{
"type": "s",
"name": "machine_uuid",
"direction": "out"
}
]
}
]
},
"org.platypush.Bus": {
"method": [
{
"name": "Post",
"args": [
{
"type": "s",
"name": "msg",
"direction": "in"
},
{
"type": "s",
"name": "response",
"direction": "out"
}
]
}
]
}
}
}
}
"""
busses = {}
response = {}
if isinstance(bus, str):
bus = (bus,)
if BusType.SYSTEM.value in bus:
busses['system'] = self._system_bus
if BusType.SESSION.value in bus:
busses['session'] = self._session_bus
for bus_name, bus in busses.items():
services = {}
service_names = self._get_bus_names(bus)
if not service:
for srv in service_names:
services.update(self.path_names(bus, srv))
elif service in service_names:
services.update(self.path_names(bus, service))
response[bus_name] = services
return response
[docs] @action
def execute(
self,
service: str,
interface: str,
method_name: str,
bus: str = BusType.SESSION.value,
path: str = '/',
args: Optional[list] = None
):
"""
Execute a method exposed on DBus.
:param service: D-Bus service name.
:param interface: D-Bus nterface name.
:param method_name: Method name.
:param bus: Bus type. Supported: ``system`` and ``session`` (default: ``session``).
:param path: Object path.
:param args: Arguments to be passed to the method, depending on the method signature.
:return: Return value of the executed method.
"""
if not args:
args = []
bus = self._get_bus(bus)
obj = bus.get(service, path)[interface]
method = getattr(obj, method_name, None)
assert method, (
f'No such method exposed by service={service}, '
f'interface={interface}: {method_name}'
)
# Normalize any lists/dictionaries to JSON strings
for i, arg in enumerate(args):
if isinstance(arg, (list, tuple, dict)):
args[i] = json.dumps(arg)
ret = method(*args)
try:
ret = json.loads(json.dumps(ret))
except Exception as e:
self.logger.debug(e)
return ret
# vim:sw=4:ts=4:et:
