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Diffstat (limited to 'src/leap/common/events/server.py')
| -rw-r--r-- | src/leap/common/events/server.py | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/src/leap/common/events/server.py b/src/leap/common/events/server.py new file mode 100644 index 0000000..d53c218 --- /dev/null +++ b/src/leap/common/events/server.py @@ -0,0 +1,176 @@ +# -*- coding: utf-8 -*- +# server.py +# Copyright (C) 2013 LEAP +# +# 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 3 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, see <http://www.gnu.org/licenses/>. +""" +A server for the events mechanism. + +A server can receive different kinds of requests from components: + + 1. Registration request: store component port number to be notified when + a specific signal arrives. + + 2. Signal request: redistribute the signal to registered components. +""" +import logging +import socket + + +from protobuf.socketrpc import RpcService +from leap.common.events import ( + events_pb2 as proto, + daemon, +) + + +logger = logging.getLogger(__name__) + + +SERVER_PORT = 8090 + +# the `registered_components` dictionary below should have the following +# format: +# +# { event_signal: [ port, ... ], ... } +# +registered_components = {} + + +def ensure_server(port=SERVER_PORT): + """ + Make sure the server is running on the given port. + + Attempt to connect to given local port. Upon success, assume that the + events server has already been started. Upon failure, start events server. + + :param port: the port in which server should be listening + :type port: int + + :return: the daemon instance or nothing + :rtype: EventsServerDaemon or None + """ + try: + s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) + s.connect(('localhost', port)) + s.close() + logger.info('Server is already running on port %d.', port) + return None + except socket.error: + logger.info('Launching server on port %d.', port) + return EventsServerDaemon.ensure(port) + + +class EventsServerService(proto.EventsServerService): + """ + Service for receiving events in components. + """ + + def register(self, controller, request, done): + """ + Register a component port to be signaled when specific events come in. + + :param controller: used to mediate a single method call + :type controller: protobuf.socketrpc.controller.SocketRpcController + :param request: the request received from the component + :type request: leap.common.events.events_pb2.RegisterRequest + :param done: callback to be called when done + :type done: protobuf.socketrpc.server.Callback + """ + logger.info("Received registration request: %s..." % str(request)[:40]) + # add component port to signal list + if request.event not in registered_components: + registered_components[request.event] = set([]) + registered_components[request.event].add(request.port) + # send response back to component + + logger.debug('sending response back') + response = proto.EventResponse() + response.status = proto.EventResponse.OK + done.run(response) + + def unregister(self, controller, request, done): + """ + Unregister a component port so it will not be signaled when specific + events come in. + + :param controller: used to mediate a single method call + :type controller: protobuf.socketrpc.controller.SocketRpcController + :param request: the request received from the component + :type request: leap.common.events.events_pb2.RegisterRequest + :param done: callback to be called when done + :type done: protobuf.socketrpc.server.Callback + """ + logger.info( + "Received unregistration request: %s..." % str(request)[:40]) + # remove component port from signal list + response = proto.EventResponse() + if request.event in registered_components: + try: + registered_components[request.event].remove(request.port) + response.status = proto.EventResponse.OK + except KeyError: + response.status = proto.EventsResponse.ERROR + response.result = 'Port %d not registered.' % request.port + # send response back to component + logger.debug('sending response back') + done.run(response) + + def signal(self, controller, request, done): + """ + Perform an RPC call to signal all components registered to receive a + specific signal. + + :param controller: used to mediate a single method call + :type controller: protobuf.socketrpc.controller.SocketRpcController + :param request: the request received from the component + :type request: leap.common.events.events_pb2.SignalRequest + :param done: callback to be called when done + :type done: protobuf.socketrpc.server.Callback + """ + logger.info('Received signal from component: %s...', str(request)[:40]) + # send signal to all registered components + # TODO: verify signal auth + if request.event in registered_components: + for port in registered_components[request.event]: + + def callback(req, resp): + logger.info("Signal received by " + str(port)) + + service = RpcService(proto.EventsComponentService_Stub, + port, 'localhost') + service.signal(request, callback=callback) + # send response back to component + response = proto.EventResponse() + response.status = proto.EventResponse.OK + done.run(response) + + +class EventsServerDaemon(daemon.EventsSingletonDaemon): + """ + Singleton class for starting an events server daemon. + """ + + @classmethod + def ensure(cls, port): + """ + Make sure the daemon is running on the given port. + + :param port: the port in which the daemon should listen + :type port: int + + :return: a daemon instance + :rtype: EventsServerDaemon + """ + return cls.ensure_service(port, EventsServerService()) |