def _on_message(self, client, userdata, msg):
"""
This handler is called when a message is received from the MQTT broker, on the subscribed topics.
The current implementation checks the validity of the message itself, by verifying its signature.
:param client: is the MQTT client reference, useful to respond back
:param userdata: metadata about the received data
:param msg: message that was received
:return: nothing, it simply handles the message accordingly.
"""
networkl.debug(msg.topic + " --> " + str(msg.payload))
try:
message = json.loads(str(msg.payload, "utf8"))
header = message['header']
message_hash = md5()
strtohash = "%s%s%s" % (header['messageId'], self._cloud_creds.key,
header['timestamp'])
message_hash.update(strtohash.encode("utf8"))
expected_signature = message_hash.hexdigest().lower()
if header['sign'] != expected_signature:
# TODO: custom exception for invalid signature
raise Exception('The signature did not match!')
# Check if there is any thread waiting for this message or if there is a callback that we need to invoke.
# If so, do it here.
handle = None
with self._pending_responses_lock:
msg_id = header['messageId']
handle = self._pending_response_messages.get(msg_id)
from_myself = False
if handle is not None:
# There was a handle for this message-id. It means it is a response message to some
# request performed by the library itself.
from_myself = True
try:
l.debug("Calling handle event handler for message %s" %
msg_id)
# Call the handler
handle.notify_message_received(error=None,
response=message)
l.debug("Done handler for message %s" % msg_id)
# Remove the message from the pending queue
with self._pending_responses_lock:
del self._pending_response_messages[msg_id]
except:
l.exception(
"Error occurred while invoking message handler")
# Let's also catch all the "PUSH" notifications and dispatch them to the push_notification_callback.
if self._push_message_callback is not None and header[
'method'] == "PUSH" and 'namespace' in header:
self._push_message_callback(message, from_myself=from_myself)
except Exception:
l.exception("Failed to process message.")
def close(self):
l.info("Closing the MQTT connection...")
self._mqtt_client.disconnect()
l.debug("Waiting for the client to disconnect...")
self.connection_status.wait_for_status(ClientStatus.CONNECTION_DROPPED)
# Starts a new thread that handles mqtt protocol and calls us back via callbacks
l.debug("Stopping the MQTT looper.")
self._mqtt_client.loop_stop(True)
l.info("Client has been fully disconnected.")
def _on_connect(self, client, userdata, rc, other):
l.debug("Connected with result code %s" % str(rc))
self.connection_status.update_status(ClientStatus.CONNECTED)
self._client_response_topic = "/app/%s-%s/subscribe" % (self._cloud_creds.user_id, self._app_id)
self._user_topic = "/app/%s/subscribe" % self._cloud_creds.user_id
# Subscribe to the relevant topics
l.debug("Subscribing to topics...")
client.subscribe(self._user_topic)
client.subscribe(self._client_response_topic)
def connect(self):
"""
Starts the connection to the MQTT broker
:return:
"""
l.info("Initializing the MQTT connection...")
self._mqtt_client.connect(self._domain, self._port, keepalive=30)
self.connection_status.update_status(ClientStatus.CONNECTING)
# Starts a new thread that handles mqtt protocol and calls us back via callbacks
l.debug("(Re)Starting the MQTT looper.")
self._mqtt_client.loop_stop(True)
self._mqtt_client.loop_start()
l.debug("Waiting for the client to connect...")
self.connection_status.wait_for_status(ClientStatus.SUBSCRIBED)
l.info("Client connected to MQTT broker and subscribed to relevant topics.")
def execute_cmd(self, dst_dev_uuid, method, namespace, payload, callback=None, timeout=SHORT_TIMEOUT):
start = time.time()
# Build the mqtt message we will send to the broker
message, message_id = self._build_mqtt_message(method, namespace, payload)
# Register the waiting handler for that message
handle = PendingMessageResponse(message_id=message_id, callback=callback)
with self._pending_responses_lock:
self._pending_response_messages[message_id] = handle
# Send the message to the broker
l.debug("Executing message-id %s, %s on %s command for device %s" % (message_id, method,
namespace, dst_dev_uuid))
self._mqtt_client.publish(topic=build_client_request_topic(dst_dev_uuid), payload=message)
# If the caller has specified a callback, we don't need to actively wait for the message ACK. So we can
# immediately return.
if callback is not None:
return None
# Otherwise, we need to wait until the message is received.
l.debug("Waiting for response to message-id %s" % message_id)
success, resp = handle.wait_for_response(timeout=timeout)
if not success:
raise CommandTimeoutException("A timeout occurred while waiting for the ACK: %d" % timeout)
elapsed = time.time() - start
l.debug("Message-id: %s, command %s-%s command for device %s took %s" % (message_id, method,
namespace, dst_dev_uuid, str(elapsed)))
return resp['payload']
def _on_subscribe(self, client, userdata, mid, granted_qos):
l.debug("Succesfully subscribed to topic. Subscription count: %d" %
self._subscription_count.get())
if self._subscription_count.inc() == 2:
self.connection_status.update_status(ClientStatus.SUBSCRIBED)
def _on_unsubscribe(self):
l.debug("Unsubscribed from topic")
self._subscription_count.dec()
def unregister_connection_event_callback(self, callback):
with self._connection_event_callbacks_lock:
if callback in self._connection_event_callbacks:
self._connection_event_callbacks.remove(callback)
else:
l.debug("Callback was present: nothing to unregister.")
def register_connection_event_callback(self, callback):
with self._connection_event_callbacks_lock:
if callback not in self._connection_event_callbacks:
self._connection_event_callbacks.append(callback)
else:
l.debug("Callback was already registered.")