""" MQTT All network operations in `awscrt.mqtt` are asynchronous. """ # Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. # SPDX-License-Identifier: Apache-2.0. import _awscrt from concurrent.futures import Future from enum import IntEnum from inspect import signature from awscrt import NativeResource import awscrt.exceptions from awscrt.http import HttpProxyOptions, HttpRequest from awscrt.io import ClientBootstrap, ClientTlsContext, SocketOptions from dataclasses import dataclass class QoS(IntEnum): """Quality of Service enumeration [MQTT-4.3] """ AT_MOST_ONCE = 0 """QoS 0 - At most once delivery The message is delivered according to the capabilities of the underlying network. No response is sent by the receiver and no retry is performed by the sender. The message arrives at the receiver either once or not at all. """ AT_LEAST_ONCE = 1 """QoS 1 - At least once delivery This quality of service ensures that the message arrives at the receiver at least once. """ EXACTLY_ONCE = 2 """QoS 2 - Exactly once delivery This is the highest quality of service, for use when neither loss nor duplication of messages are acceptable. There is an increased overhead associated with this quality of service. Note that, while this client supports QoS 2, the AWS IoT Core server does not support QoS 2 at time of writing (May 2020). """ def _try_qos(qos_value): """Return None if the value cannot be converted to Qos (ex: 0x80 subscribe failure)""" try: return QoS(qos_value) except Exception: return None class ConnectReturnCode(IntEnum): """Connect return code enumeration. [MQTT-3.2.2.3] """ ACCEPTED = 0 """Connection Accepted.""" UNACCEPTABLE_PROTOCOL_VERSION = 1 """Connection Refused, unacceptable protocol version. The Server does not support the level of the MQTT protocol requested by the Client. """ IDENTIFIER_REJECTED = 2 """Connection Refused, identifier rejected. The Client identifier is correct UTF-8 but not allowed by the Server. """ SERVER_UNAVAILABLE = 3 """Connection Refused, Server unavailable. The Network Connection has been made but the MQTT service is unavailable. """ BAD_USERNAME_OR_PASSWORD = 4 """Connection Refused, bad user name or password. The data in the user name or password is malformed. """ NOT_AUTHORIZED = 5 """Connection Refused, not authorized. The Client is not authorized to connect. """ class Will: """A Will message is published by the server if a client is lost unexpectedly. The Will message is stored on the server when a client connects. It is published if the client connection is lost without the server receiving a DISCONNECT packet. [MQTT-3.1.2-8] Args: topic (str): Topic to publish Will message on. qos (QoS): QoS used when publishing the Will message. payload (bytes): Content of Will message. retain (bool): Whether the Will message is to be retained when it is published. Attributes: topic (str): Topic to publish Will message on. qos (QoS): QoS used when publishing the Will message. payload (bytes): Content of Will message. retain (bool): Whether the Will message is to be retained when it is published. """ __slots__ = ('topic', 'qos', 'payload', 'retain') def __init__(self, topic, qos, payload, retain): self.topic = topic self.qos = qos self.payload = payload self.retain = retain class Client(NativeResource): """MQTT client. Args: bootstrap (Optional [ClientBootstrap]): Client bootstrap to use when initiating new socket connections. If None is provided, the default singleton is used. tls_ctx (Optional[ClientTlsContext]): TLS context for secure socket connections. If None is provided, then an unencrypted connection is used. """ __slots__ = ('tls_ctx') def __init__(self, bootstrap=None, tls_ctx=None): assert isinstance(bootstrap, ClientBootstrap) or bootstrap is None assert tls_ctx is None or isinstance(tls_ctx, ClientTlsContext) super().__init__() self.tls_ctx = tls_ctx if not bootstrap: bootstrap = ClientBootstrap.get_or_create_static_default() self._binding = _awscrt.mqtt_client_new(bootstrap, tls_ctx) @dataclass class OperationStatisticsData: """Dataclass containing some simple statistics about the current state of the connection's queue of operations Args: incomplete_operation_count (int): total number of operations submitted to the connection that have not yet been completed. Unacked operations are a subset of this. incomplete_operation_size (int): total packet size of operations submitted to the connection that have not yet been completed. Unacked operations are a subset of this. unacked_operation_count (int): total number of operations that have been sent to the server and are waiting for a corresponding ACK before they can be completed. unacked_operation_size (int): total packet size of operations that have been sent to the server and are waiting for a corresponding ACK before they can be completed. """ incomplete_operation_count: int = 0 incomplete_operation_size: int = 0 unacked_operation_count: int = 0 unacked_operation_size: int = 0 class Connection(NativeResource): """MQTT client connection. Args: client (Client): MQTT client to spawn connection from. host_name (str): Server name to connect to. port (int): Server port to connect to. client_id (str): ID to place in CONNECT packet. Must be unique across all devices/clients. If an ID is already in use, the other client will be disconnected. clean_session (bool): Whether or not to start a clean session with each reconnect. If True, the server will forget all subscriptions with each reconnect. Set False to request that the server resume an existing session or start a new session that may be resumed after a connection loss. The `session_present` bool in the connection callback informs whether an existing session was successfully resumed. If an existing session is resumed, the server remembers previous subscriptions and sends mesages (with QoS1 or higher) that were published while the client was offline. on_connection_interrupted: Optional callback invoked whenever the MQTT connection is lost. The MQTT client will automatically attempt to reconnect. The function should take the following arguments return nothing: * `connection` (:class:`Connection`): This MQTT Connection. * `error` (:class:`awscrt.exceptions.AwsCrtError`): Exception which caused connection loss. * `**kwargs` (dict): Forward-compatibility kwargs. on_connection_resumed: Optional callback invoked whenever the MQTT connection is automatically resumed. Function should take the following arguments and return nothing: * `connection` (:class:`Connection`): This MQTT Connection * `return_code` (:class:`ConnectReturnCode`): Connect return code received from the server. * `session_present` (bool): True if resuming existing session. False if new session. Note that the server has forgotten all previous subscriptions if this is False. Subscriptions can be re-established via resubscribe_existing_topics(). * `**kwargs` (dict): Forward-compatibility kwargs. reconnect_min_timeout_secs (int): Minimum time to wait between reconnect attempts. Must be <= `reconnect_max_timeout_secs`. Wait starts at min and doubles with each attempt until max is reached. reconnect_max_timeout_secs (int): Maximum time to wait between reconnect attempts. Must be >= `reconnect_min_timeout_secs`. Wait starts at min and doubles with each attempt until max is reached. keep_alive_secs (int): The keep alive value, in seconds, to send in CONNECT packet. A PING will automatically be sent at this interval. The server will assume the connection is lost if no PING is received after 1.5X this value. This duration must be longer than ping_timeout_ms. ping_timeout_ms (int): Milliseconds to wait for ping response before client assumes the connection is invalid and attempts to reconnect. This duration must be shorter than `keep_alive_secs`. protocol_operation_timeout_ms (int): Milliseconds to wait for the response to the operation requires response by protocol. Set to zero to disable timeout. Otherwise, the operation will fail if no response is received within this amount of time after the packet is written to the socket It applied to PUBLISH (QoS>0) and UNSUBSCRIBE now. will (Will): Will to send with CONNECT packet. The will is published by the server when its connection to the client is unexpectedly lost. username (str): Username to connect with. password (str): Password to connect with. socket_options (Optional[awscrt.io.SocketOptions]): Optional socket options. use_websocket (bool): If true, connect to MQTT over websockets. websocket_proxy_options (Optional[awscrt.http.HttpProxyOptions]): Optional proxy options for websocket connections. Deprecated, use `proxy_options` instead. websocket_handshake_transform: Optional function to transform websocket handshake request. If provided, function is called each time a websocket connection is attempted. The function may modify the HTTP request before it is sent to the server. See :class:`WebsocketHandshakeTransformArgs` for more info. Function should take the following arguments and return nothing: * `transform_args` (:class:`WebsocketHandshakeTransformArgs`): Contains HTTP request to be transformed. Function must call `transform_args.done()` when complete. * `**kwargs` (dict): Forward-compatibility kwargs. proxy_options (Optional[awscrt.http.HttpProxyOptions]): Optional proxy options for all connections. """ def __init__(self, client, host_name, port, client_id, clean_session=True, on_connection_interrupted=None, on_connection_resumed=None, reconnect_min_timeout_secs=5, reconnect_max_timeout_secs=60, keep_alive_secs=1200, ping_timeout_ms=3000, protocol_operation_timeout_ms=0, will=None, username=None, password=None, socket_options=None, use_websockets=False, websocket_proxy_options=None, websocket_handshake_transform=None, proxy_options=None ): assert isinstance(client, Client) assert callable(on_connection_interrupted) or on_connection_interrupted is None assert callable(on_connection_resumed) or on_connection_resumed is None assert isinstance(will, Will) or will is None assert isinstance(socket_options, SocketOptions) or socket_options is None assert isinstance(websocket_proxy_options, HttpProxyOptions) or websocket_proxy_options is None assert isinstance(proxy_options, HttpProxyOptions) or proxy_options is None assert callable(websocket_handshake_transform) or websocket_handshake_transform is None if reconnect_min_timeout_secs > reconnect_max_timeout_secs: raise ValueError("'reconnect_min_timeout_secs' cannot exceed 'reconnect_max_timeout_secs'") if keep_alive_secs * 1000 <= ping_timeout_ms: raise ValueError("'keep_alive_secs' duration must be longer than 'ping_timeout_ms'") if proxy_options and websocket_proxy_options: raise ValueError("'websocket_proxy_options' has been deprecated in favor of 'proxy_options'. " "Both parameters may not be set.") super().__init__() # init-only self.client = client self._on_connection_interrupted_cb = on_connection_interrupted self._on_connection_resumed_cb = on_connection_resumed self._use_websockets = use_websockets self._ws_handshake_transform_cb = websocket_handshake_transform # may be changed at runtime, take effect the the next time connect/reconnect occurs self.client_id = client_id self.host_name = host_name self.port = port self.clean_session = clean_session self.reconnect_min_timeout_secs = reconnect_min_timeout_secs self.reconnect_max_timeout_secs = reconnect_max_timeout_secs self.keep_alive_secs = keep_alive_secs self.ping_timeout_ms = ping_timeout_ms self.protocol_operation_timeout_ms = protocol_operation_timeout_ms self.will = will self.username = username self.password = password self.socket_options = socket_options if socket_options else SocketOptions() self.proxy_options = proxy_options if proxy_options else websocket_proxy_options self._binding = _awscrt.mqtt_client_connection_new( self, client, use_websockets, ) def _check_uses_old_message_callback_signature(self, callback): # The callback used to have fewer args. Passing only those args, if it # only has two args and no forward-compatibility to cover case where # user function failed to take forward-compatibility **kwargs. callback_sig = signature(callback) try: # try new signature callback_sig.bind(topic='topic', payload='payload', dup=True, qos=QoS(1), retain=True) return False except TypeError: # try old signature callback_sig.bind(topic='topic', payload='payload') return True def _on_connection_interrupted(self, error_code): if self._on_connection_interrupted_cb: self._on_connection_interrupted_cb(connection=self, error=awscrt.exceptions.from_code(error_code)) def _on_connection_resumed(self, return_code, session_present): if self._on_connection_resumed_cb: self._on_connection_resumed_cb( connection=self, return_code=ConnectReturnCode(return_code), session_present=session_present) def _ws_handshake_transform(self, http_request_binding, http_headers_binding, native_userdata): if self._ws_handshake_transform_cb is None: _awscrt.mqtt_ws_handshake_transform_complete(None, native_userdata) return def _on_complete(f): _awscrt.mqtt_ws_handshake_transform_complete(f.exception(), native_userdata) future = Future() future.add_done_callback(_on_complete) http_request = HttpRequest._from_bindings(http_request_binding, http_headers_binding) transform_args = WebsocketHandshakeTransformArgs(self, http_request, future) try: self._ws_handshake_transform_cb(transform_args=transform_args) except Exception as e: # Call set_done() if user failed to do so before uncaught exception was raised, # there's a chance the callback wasn't callable and user has no idea we tried to hand them the baton. if not future.done(): transform_args.set_done(e) def connect(self): """Open the actual connection to the server (async). Returns: concurrent.futures.Future: Future which completes when connection succeeds or fails. If connection fails, Future will contain an exception. If connection succeeds, Future will contain a dict with the following members: * ['session_present'] (bool): is True if resuming existing session and False if new session. """ future = Future() def on_connect(error_code, return_code, session_present): if return_code: future.set_exception(Exception(ConnectReturnCode(return_code))) elif error_code: future.set_exception(awscrt.exceptions.from_code(error_code)) else: future.set_result(dict(session_present=session_present)) try: _awscrt.mqtt_client_connection_connect( self._binding, self.client_id, self.host_name, self.port, self.socket_options, self.client.tls_ctx, self.reconnect_min_timeout_secs, self.reconnect_max_timeout_secs, self.keep_alive_secs, self.ping_timeout_ms, self.protocol_operation_timeout_ms, self.will, self.username, self.password, self.clean_session, on_connect, self.proxy_options ) except Exception as e: future.set_exception(e) return future def reconnect(self): """DEPRECATED. awscrt.mqtt.ClientConnection automatically reconnects. To cease reconnect attempts, call disconnect(). To resume the connection, call connect(). """ future = Future() def on_connect(error_code, return_code, session_present): if return_code: future.set_exception(Exception(ConnectReturnCode(return_code))) elif error_code: future.set_exception(awscrt.exceptions.from_code(error_code)) else: future.set_result(dict(session_present=session_present)) try: _awscrt.mqtt_client_connection_reconnect(self._binding, on_connect) except Exception as e: future.set_exception(e) return future def disconnect(self): """Close the connection (async). Returns: concurrent.futures.Future: Future which completes when the connection is closed. The future will contain an empty dict. """ future = Future() def on_disconnect(): future.set_result(dict()) try: _awscrt.mqtt_client_connection_disconnect(self._binding, on_disconnect) except Exception as e: future.set_exception(e) return future def subscribe(self, topic, qos, callback=None): """Subscribe to a topic filter (async). The client sends a SUBSCRIBE packet and the server responds with a SUBACK. subscribe() may be called while the device is offline, though the async operation cannot complete successfully until the connection resumes. Once subscribed, `callback` is invoked each time a message matching the `topic` is received. It is possible for such messages to arrive before the SUBACK is received. Args: topic (str): Subscribe to this topic filter, which may include wildcards. qos (QoS): Maximum requested QoS that server may use when sending messages to the client. The server may grant a lower QoS in the SUBACK (see returned Future) callback: Optional callback invoked when message received. Function should take the following arguments and return nothing: * `topic` (str): Topic receiving message. * `payload` (bytes): Payload of message. * `dup` (bool): DUP flag. If True, this might be re-delivery of an earlier attempt to send the message. * `qos` (:class:`QoS`): Quality of Service used to deliver the message. * `retain` (bool): Retain flag. If True, the message was sent as a result of a new subscription being made by the client. * `**kwargs` (dict): Forward-compatibility kwargs. Returns: Tuple[concurrent.futures.Future, int]: Tuple containing a Future and the ID of the SUBSCRIBE packet. The Future completes when a SUBACK is received from the server. If successful, the Future will contain a dict with the following members: * ['packet_id'] (int): ID of the SUBSCRIBE packet being acknowledged. * ['topic'] (str): Topic filter of the SUBSCRIBE packet being acknowledged. * ['qos'] (:class:`QoS`): Maximum QoS that was granted by the server. This may be lower than the requested QoS. If unsuccessful, the Future contains an exception. The exception will be a :class:`SubscribeError` if a SUBACK was received in which the server rejected the subscription. Other exception types indicate other errors with the operation. """ future = Future() packet_id = 0 if callback: uses_old_signature = self._check_uses_old_message_callback_signature(callback) def callback_wrapper(topic, payload, dup, qos, retain): if uses_old_signature: callback(topic=topic, payload=payload) else: callback(topic=topic, payload=payload, dup=dup, qos=QoS(qos), retain=retain) else: callback_wrapper = None def suback(packet_id, topic, qos, error_code): if error_code: future.set_exception(awscrt.exceptions.from_code(error_code)) else: qos = _try_qos(qos) if qos is None: future.set_exception(SubscribeError(topic)) else: future.set_result(dict( packet_id=packet_id, topic=topic, qos=qos, )) try: assert callable(callback) or callback is None assert isinstance(qos, QoS) packet_id = _awscrt.mqtt_client_connection_subscribe( self._binding, topic, qos.value, callback_wrapper, suback) except Exception as e: future.set_exception(e) return future, packet_id def on_message(self, callback): """Set callback to be invoked when ANY message is received. callback: Callback to invoke when message received, or None to disable. Function should take the following arguments and return nothing: * `topic` (str): Topic receiving message. * `payload` (bytes): Payload of message. * `dup` (bool): DUP flag. If True, this might be re-delivery of an earlier attempt to send the message. * `qos` (:class:`QoS`): Quality of Service used to deliver the message. * `retain` (bool): Retain flag. If True, the message was sent as a result of a new subscription being made by the client. * `**kwargs` (dict): Forward-compatibility kwargs. """ assert callable(callback) or callback is None if callback: uses_old_signature = self._check_uses_old_message_callback_signature(callback) def callback_wrapper(topic, payload, dup, qos, retain): if uses_old_signature: callback(topic=topic, payload=payload) else: callback(topic=topic, payload=payload, dup=dup, qos=QoS(qos), retain=retain) else: callback_wrapper = None _awscrt.mqtt_client_connection_on_message(self._binding, callback_wrapper) def unsubscribe(self, topic): """Unsubscribe from a topic filter (async). The client sends an UNSUBSCRIBE packet, and the server responds with an UNSUBACK. Args: topic (str): Unsubscribe from this topic filter. Returns: Tuple[concurrent.futures.Future, int]: Tuple containing a Future and the ID of the UNSUBSCRIBE packet. The Future completes when an UNSUBACK is received from the server. If successful, the Future will contain a dict with the following members: * ['packet_id'] (int): ID of the UNSUBSCRIBE packet being acknowledged. """ future = Future() packet_id = 0 def unsuback(packet_id, error_code): if error_code != 0: future.set_exception(awscrt.exceptions.from_code(error_code)) else: future.set_result(dict(packet_id=packet_id)) try: packet_id = _awscrt.mqtt_client_connection_unsubscribe(self._binding, topic, unsuback) except Exception as e: future.set_exception(e) return future, packet_id def resubscribe_existing_topics(self): """ Subscribe again to all current topics. This is to help when resuming a connection with a clean session. Returns: Tuple[concurrent.futures.Future, int]: Tuple containing a Future and the ID of the SUBSCRIBE packet. The Future completes when a SUBACK is received from the server. If successful, the Future will contain a dict with the following members: * ['packet_id']: ID of the SUBSCRIBE packet being acknowledged, or None if there were no topics to resubscribe to. * ['topics']: A list of (topic, qos) tuples, where qos will be None if the topic failed to resubscribe. If there were no topics to resubscribe to, then the list will be empty. """ packet_id = 0 future = Future() def on_suback(packet_id, topic_qos_tuples, error_code): if error_code: future.set_exception(awscrt.exceptions.from_code(error_code)) else: future.set_result(dict( packet_id=packet_id, topics=[(topic, _try_qos(qos)) for (topic, qos) in topic_qos_tuples], )) try: packet_id = _awscrt.mqtt_client_connection_resubscribe_existing_topics(self._binding, on_suback) if packet_id is None: # There were no topics to resubscribe to. future.set_result(dict(packet_id=None, topics=[])) except Exception as e: future.set_exception(e) return future, packet_id def publish(self, topic, payload, qos, retain=False): """Publish message (async). If the device is offline, the PUBLISH packet will be sent once the connection resumes. Args: topic (str): Topic name. payload (Union[str, bytes, bytearray]): Contents of message. qos (QoS): Quality of Service for delivering this message. retain (bool): If True, the server will store the message and its QoS so that it can be delivered to future subscribers whose subscriptions match its topic name. Returns: Tuple[concurrent.futures.Future, int]: Tuple containing a Future and the ID of the PUBLISH packet. The QoS determines when the Future completes: * For QoS 0, completes as soon as the packet is sent. * For QoS 1, completes when PUBACK is received. * For QoS 2, completes when PUBCOMP is received. If successful, the Future will contain a dict with the following members: * ['packet_id'] (int): ID of the PUBLISH packet that is complete. """ future = Future() packet_id = 0 def puback(packet_id, error_code): if error_code != 0: future.set_exception(awscrt.exceptions.from_code(error_code)) else: future.set_result(dict(packet_id=packet_id)) try: packet_id = _awscrt.mqtt_client_connection_publish(self._binding, topic, payload, qos.value, retain, puback) except Exception as e: future.set_exception(e) return future, packet_id def get_stats(self): """Queries the connection's internal statistics for incomplete operations. Returns: The (:class:`OperationStatisticsData`) containing the statistics """ result = _awscrt.mqtt_client_connection_get_stats(self._binding) return OperationStatisticsData(result[0], result[1], result[2], result[3]) class WebsocketHandshakeTransformArgs: """ Argument to a "websocket_handshake_transform" function. A websocket_handshake_transform function has signature: ``fn(transform_args: WebsocketHandshakeTransformArgs, **kwargs) -> None`` The function implementer may modify `transform_args.http_request` as desired. They MUST call `transform_args.set_done()` when complete, passing an exception if something went wrong. Failure to call `set_done()` will hang the application. The implementer may do asynchronous work before calling `transform_args.set_done()`, they are not required to call `set_done()` within the scope of the transform function. An example of async work would be to fetch credentials from another service, sign the request headers, and finally call `set_done()` to mark the transform complete. The default websocket handshake request uses path "/mqtt". All required headers are present, plus the optional header "Sec-WebSocket-Protocol: mqtt". Args: mqtt_connection (Connection): Connection this handshake is for. http_request (awscrt.http.HttpRequest): HTTP request for this handshake. done_future (concurrent.futures.Future): Future to complete when the :meth:`set_done()` is called. It will contain None if successful, or an exception will be set. Attributes: mqtt_connection (Connection): Connection this handshake is for. http_request (awscrt.http.HttpRequest): HTTP request for this handshake. """ def __init__(self, mqtt_connection, http_request, done_future): self.mqtt_connection = mqtt_connection self.http_request = http_request self._done_future = done_future def set_done(self, exception=None): """ Mark the transformation complete. If exception is passed in, the handshake is canceled. """ if exception is None: self._done_future.set_result(None) else: self._done_future.set_exception(exception) class SubscribeError(Exception): """ Subscription rejected by server. """ pass