mirror of
https://github.com/avatao-content/baseimage-tutorial-framework
synced 2024-11-23 04:41:31 +00:00
73 lines
2.5 KiB
Python
73 lines
2.5 KiB
Python
import logging
|
|
|
|
from tfw.crypto import KeyManager, sign_message, verify_message
|
|
from tfw.networking import Scope
|
|
from tfw.components import FSMUpdater
|
|
|
|
from .event_handler import EventHandler
|
|
|
|
LOG = logging.getLogger(__name__)
|
|
|
|
|
|
class FSMManagingEventHandler(EventHandler):
|
|
"""
|
|
EventHandler responsible for managing the state machine of
|
|
the framework (TFW FSM).
|
|
|
|
tfw.networking.TFWServer instances automatically send 'trigger'
|
|
commands to the event handler listening on the 'fsm' key,
|
|
which should be an instance of this event handler.
|
|
|
|
This event handler accepts messages that have a
|
|
data['command'] key specifying a command to be executed.
|
|
|
|
An 'fsm_update' message is broadcasted after every successful
|
|
command.
|
|
"""
|
|
def __init__(self, key, fsm_type, require_signature=False):
|
|
super().__init__(key, scope=Scope.WEBSOCKET)
|
|
self.fsm = fsm_type()
|
|
self._fsm_updater = FSMUpdater(self.fsm)
|
|
self.auth_key = KeyManager().auth_key
|
|
self._require_signature = require_signature
|
|
|
|
self.command_handlers = {
|
|
'trigger': self.handle_trigger,
|
|
'update': self.handle_update
|
|
}
|
|
|
|
def handle_event(self, message):
|
|
try:
|
|
message = self.command_handlers[message['data']['command']](message)
|
|
if message:
|
|
fsm_update_message = self._fsm_updater.fsm_update
|
|
sign_message(self.auth_key, message)
|
|
sign_message(self.auth_key, fsm_update_message)
|
|
self.server_connector.send_message(fsm_update_message, Scope.BROADCAST)
|
|
self.send_message(message)
|
|
except KeyError:
|
|
LOG.error('IGNORING MESSAGE: Invalid message received: %s', message)
|
|
|
|
def handle_trigger(self, message):
|
|
"""
|
|
Attempts to step the FSM with the supplied trigger.
|
|
|
|
:param message: TFW message with a data field containing
|
|
the action to try triggering in data['value']
|
|
"""
|
|
trigger = message['data']['value']
|
|
if self._require_signature:
|
|
if not verify_message(self.auth_key, message):
|
|
LOG.error('Ignoring unsigned trigger command: %s', message)
|
|
return None
|
|
if self.fsm.step(trigger):
|
|
return message
|
|
return None
|
|
|
|
def handle_update(self, message):
|
|
"""
|
|
Does nothing, but triggers an 'fsm_update' message.
|
|
"""
|
|
# pylint: disable=no-self-use
|
|
return message
|