This module provides implementation of MQTT wrapper for Paho MQTT.

MQ Telemetry Transport (MQTT) is a lightweight broker-based publish/subscribe messaging protocol designed to be open, simple, lightweight and easy to implement.

Revision history 2014/10/07 : Initial draft. (v1.0)

Data Structures
struct	mqtt_client_pool

struct	mqtt_config
	MQTT configuration structure. More...

union	mqtt_data
	Structure of the MQTT callback. More...

struct	mqtt_data_connected
	Structure of the MQTT_CALLBACK_CONNECTED callback. More...

struct	mqtt_data_disconnected
	Structure of the MQTT_CALLBACK_DISCONNECTED callback. More...

struct	mqtt_data_ping
	Structure of the MQTT_CALLBACK_SENT_PING callback. More...

struct	mqtt_data_published
	Structure of the MQTT_CALLBACK_PUBLISHED callback. More...

struct	mqtt_data_sock_connected
	Structure of the MQTT_CALLBACK_SOCK_CONNECTED callback. More...

struct	mqtt_data_subscribed
	Structure of the MQTT_CALLBACK_SUBSCRIBED callback. More...

struct	mqtt_data_unsubscribed
	Structure of the MQTT_CALLBACK_UNSUBSCRIBED callback. More...

struct	mqtt_module
	Structure of MQTT connection instance. More...

Typedefs
typedef void(*	mqtt_callback_t )(struct mqtt_module module_inst, int type, union mqtt_data data)
	Callback interface of MQTT service. More...

Enumerations
enum	mqtt_callback_type { MQTT_CALLBACK_SOCK_CONNECTED, MQTT_CALLBACK_CONNECTED, MQTT_CALLBACK_PUBLISHED, MQTT_CALLBACK_SUBSCRIBED, MQTT_CALLBACK_UNSUBSCRIBED, MQTT_CALLBACK_DISCONNECTED, MQTT_CALLBACK_SENT_PING }
	A type of MQTT callback. More...

enum	mqtt_conn_result { MQTT_CONN_RESULT_ACCEPT = 0, MQTT_CONN_RESULT_UNACCEPTABLE_VERSION, MQTT_CONN_RESULT_ID_REJECTED, MQTT_CONN_RESULT_SERVER_UNAVAILABLE, MQTT_CONN_RESULT_BAD_USER_NAME, MQTT_CONN_RESULT_NOT_AUTHORIZED }
	Connect return code. More...

Functions
int	mqtt_connect (struct mqtt_module const module, const char host)
	Connect to specific MQTT broker server. More...

int	mqtt_connect_broker (struct mqtt_module const module, uint8_t clean_session, const char id, const char password, const char client_id, const char will_topic, const char will_msg, uint32_t will_msg_len, uint8_t will_qos, uint8_t will_retain)
	Send MQTT connect message to broker server with MQTT parameter. More...

int	mqtt_deinit (struct mqtt_module *const module)
	Termivate MQTT service. More...

int	mqtt_disconnect (struct mqtt_module *const module, int force_close)
	Send disconnect message to MQTT broker server and closing socket. More...

void	mqtt_get_config_defaults (struct mqtt_config *const config)
	Get default configuration of SW timer. More...

int	mqtt_init (struct mqtt_module module, struct mqtt_config config)
	Initialize MQTT service. More...

int	mqtt_publish (struct mqtt_module const module, const char topic, const char *msg, uint32_t msg_len, uint8_t qos, uint8_t retain)
	Send publish message to MQTT broker server. More...

int	mqtt_register_callback (struct mqtt_module *const module, mqtt_callback_t callback)
	Register and enable the callback. More...

void	mqtt_socket_event_handler (SOCKET sock, uint8_t msg_type, void *msg_data)
	Event handler of socket event. More...

void	mqtt_socket_resolve_handler (uint8_t *doamin_name, uint32_t server_ip)
	Event handler of gethostbyname. More...

int	mqtt_subscribe (struct mqtt_module const module, const char topic, uint8_t qos, messageHandler msgHandler)
	Send subscribe message to MQTT broker server. More...

int	mqtt_unregister_callback (struct mqtt_module *const module)
	Unregister callback. More...

int	mqtt_unsubscribe (struct mqtt_module const module, const char topic)
	Send unsubscribe message to MQTT broker server. More...

int	mqtt_yield (struct mqtt_module *module, int timeout_ms)
	Poll for published frames. More...

Variables
struct mqtt_client_pool	mqttClientPool [MQTT_MAX_CLIENTS]
	Static Client Pool Allocation. More...

typedef void(* mqtt_callback_t)(struct mqtt_module *module_inst, int type, union mqtt_data *data)

Callback interface of MQTT service.

enum mqtt_callback_type

A type of MQTT callback.

Enumerator
MQTT_CALLBACK_SOCK_CONNECTED	Socket was connected. After received this event, try connect to broker server using mqtt_connect_broker.
MQTT_CALLBACK_CONNECTED	MQTT connection was connected to broker server.
MQTT_CALLBACK_PUBLISHED	The publish operation is completed.
MQTT_CALLBACK_SUBSCRIBED	The subscribe operation is completed.
MQTT_CALLBACK_UNSUBSCRIBED	The unsubscribe operation is completed.
MQTT_CALLBACK_DISCONNECTED	The disconnection operation is completed.
MQTT_CALLBACK_SENT_PING	The PING operation is completed.

enum mqtt_conn_result

Connect return code.

The connect return code is sent in the variable header of a CONNACK message.

Enumerator
MQTT_CONN_RESULT_ACCEPT	Connection Accepted.
MQTT_CONN_RESULT_UNACCEPTABLE_VERSION	Connection Refused: unacceptable protocol version.
MQTT_CONN_RESULT_ID_REJECTED	Connection Refused: identifier rejected.
MQTT_CONN_RESULT_SERVER_UNAVAILABLE	Connection Refused: server unavailable.
MQTT_CONN_RESULT_BAD_USER_NAME	Connection Refused: bad user name or password.
MQTT_CONN_RESULT_NOT_AUTHORIZED	Connection Refused: not authorized.

int mqtt_connect	(	struct mqtt_module *const	module,
		const char *	host
	)

Connect to specific MQTT broker server.

This function is responsible only connect the socket. If operation of this function is complete, MQTT_CALLBACK_SOCK_CONNECTED event will be sent through MQTT callback.

Parameters

[in]	module_inst	Instance of MQTT module.
[in]	host	URL of MQTT broker server.

Returns: 0 Function succeeded; -ENOENT No such address.; -EINVAL Invalid argument.; -ENOSPC No space left on device.; -EIO Device was occurred error due to unknown exception.; -EDESTADDRREQ Destination address required.; -ECONNRESET Connection reset by peer.; -EAGAIN Try again.; -EBUSY Device or resource busy.; -EADDRINUSE Address already in use.; -EALREADY Socket already connected.; -ENOTCONN Service in bad state.; -ECONNREFUSED Connection refused.; -EOVERFLOW Value too large for defined data type.; -EBADMSG Not a data message.

References mqtt_module::callback, mqtt_module::config, ConnectNetwork(), MQTT_CALLBACK_SOCK_CONNECTED, mqtt_module::network, mqtt_config::port, mqtt_data_sock_connected::result, mqtt_data::sock_connected, and mqtt_config::tls.

Referenced by mqtt_callback(), PROCESS_THREAD(), and wifi_callback().

int mqtt_connect_broker	(	struct mqtt_module *const	module,
		uint8_t	clean_session,
		const char *	id,
		const char *	password,
		const char *	client_id,
		const char *	will_topic,
		const char *	will_msg,
		uint32_t	will_msg_len,
		uint8_t	will_qos,
		uint8_t	will_retain
	)

Send MQTT connect message to broker server with MQTT parameter.

If operation of this function is complete, MQTT_CALLBACK_CONNECTED event will be sent through MQTT callback.

Parameters

[in]	module_inst	Instance of MQTT module.
[in]	clean_session	If this value set to 1, Broker server store the previous subscribed informations after disconnected.
[in]	id	ID of user.
[in]	password	Password of user.
[in]	client_id	Client ID of this connection.
[in]	will_topic	A MQTT topic that will be sent to subscribers when this connection is disconnected.
[in]	will_msg	A MQTT payload that will be sent to subscribers when this connection is disconnected.
[in]	will_qos	QOS level of will message.
[in]	will_retain	Whether broker server will be store MQTT will message or not.

Returns: 0 Function succeeded; -ENOENT No such address.; -EINVAL Invalid argument.; -ENOSPC No space left on device.; -EIO Device was occurred error due to unknown exception.; -EDESTADDRREQ Destination address required.; -ECONNRESET Connection reset by peer.; -EAGAIN Try again.; -EBUSY Device or resource busy.; -EADDRINUSE Address already in use.; -EALREADY Socket already connected.; -ENOTCONN Service in bad state.; -ECONNREFUSED Connection refused.; -EOVERFLOW Value too large for defined data type.; -EBADMSG Not a data message.

References mqtt_module::callback, mqtt_module::client, mqtt_data::connected, mqtt_module::isConnected, MQTT_CALLBACK_CONNECTED, MQTTConnect(), MQTTPacket_connectData_initializer, and mqtt_data_connected::result.

Referenced by mqtt_callback().

int mqtt_deinit ( struct mqtt_module *const module )

Termivate MQTT service.

Parameters

[in] module Module instance of MQTT.

Returns: 0 Function succeeded; -ENOENT No such address.; -EINVAL Invalid argument.; -ENOSPC No space left on device.; -EIO Device was occurred error due to unknown exception.; -EDESTADDRREQ Destination address required.; -ECONNRESET Connection reset by peer.; -EAGAIN Try again.; -EBUSY Device or resource busy.; -EADDRINUSE Address already in use.; -EALREADY Socket already connected.; -ENOTCONN Service in bad state.; -ECONNREFUSED Connection refused.; -EOVERFLOW Value too large for defined data type.; -EBADMSG Not a data message.; -ENOMEM Out of memory.

References deAllocateClient(), FAILURE, mqtt_module::isConnected, mqtt_disconnect(), and SUCCESS.

int mqtt_disconnect	(	struct mqtt_module *const	module,
		int	force_close
	)

Send disconnect message to MQTT broker server and closing socket.

If operation of this function is complete, MQTT_CALLBACK_DISCONNECTED event will be sent through MQTT callback.

Parameters

[in]	module_inst	Instance of MQTT module.
[in]	force_close	If this flag is set, MQTT service will be close the socket immediately.

Returns: 0 Function succeeded; -ENOENT No such address.; -EINVAL Invalid argument.; -ENOSPC No space left on device.; -EIO Device was occurred error due to unknown exception.; -EDESTADDRREQ Destination address required.; -ECONNRESET Connection reset by peer.; -EAGAIN Try again.; -EBUSY Device or resource busy.; -EADDRINUSE Address already in use.; -EALREADY Socket already connected.; -ENOTCONN Service in bad state.; -ECONNREFUSED Connection refused.; -EOVERFLOW Value too large for defined data type.; -EBADMSG Not a data message.

References mqtt_module::callback, mqtt_module::client, mqtt_data::disconnected, mqtt_module::isConnected, MQTT_CALLBACK_DISCONNECTED, MQTTDisconnect(), and mqtt_data_disconnected::reason.

Referenced by mqtt_deinit(), PROCESS_THREAD(), and wifi_callback().

void mqtt_get_config_defaults ( struct mqtt_config *const config )

Get default configuration of SW timer.

Parameters

[in] config Pointer of configuration structure which will be used in the module.

References mqtt_config::keep_alive, NULL, mqtt_config::port, mqtt_config::read_buffer, mqtt_config::read_buffer_size, mqtt_config::send_buffer, mqtt_config::send_buffer_size, and mqtt_config::tls.

Referenced by configure_mqtt().

int mqtt_init	(	struct mqtt_module *	module,
		struct mqtt_config *	config
	)

Initialize MQTT service.

Parameters

[in]	module	Module instance of MQTT.
[in]	config	Pointer of configuration structure which will be used in the module.

Returns: 0 Function succeeded; -ENOENT No such address.; -EINVAL Invalid argument.; -ENOSPC No space left on device.; -EIO Device was occurred error due to unknown exception.; -EDESTADDRREQ Destination address required.; -ECONNRESET Connection reset by peer.; -EAGAIN Try again.; -EBUSY Device or resource busy.; -EADDRINUSE Address already in use.; -EALREADY Socket already connected.; -ENOTCONN Service in bad state.; -ECONNREFUSED Connection refused.; -EOVERFLOW Value too large for defined data type.; -EBADMSG Not a data message.; -ENOMEM Out of memory.

References allocateClient(), mqtt_module::client, mqtt_module::config, FAILURE, mqtt_config::keep_alive, MQTTClientInit(), mqtt_module::network, NetworkInit(), NULL, mqtt_config::read_buffer, mqtt_config::read_buffer_size, mqtt_config::send_buffer, mqtt_config::send_buffer_size, and SUCCESS.

Referenced by configure_mqtt().

int mqtt_publish	(	struct mqtt_module *const	module,
		const char *	topic,
		const char *	msg,
		uint32_t	msg_len,
		uint8_t	qos,
		uint8_t	retain
	)

Send publish message to MQTT broker server.

If operation of this function is complete, MQTT_CALLBACK_PUBLISHED event will be sent through MQTT callback.

Parameters

[in]	module_inst	Instance of MQTT module.
[in]	topic	Topic of this MQTT message.
[in]	msg	Payload of this MQTT message.
[in]	msg_len	Payload size of this MQTT message.
[in]	qos	QOS level of this MQTT message. (0 <= qos <= 2)
[in]	retain	Whether broker server will be store this MQTT message or not.

Returns: 0 Function succeeded; -ENOENT No such address.; -EINVAL Invalid argument.; -ENOSPC No space left on device.; -EIO Device was occurred error due to unknown exception.; -EDESTADDRREQ Destination address required.; -ECONNRESET Connection reset by peer.; -EAGAIN Try again.; -EBUSY Device or resource busy.; -EADDRINUSE Address already in use.; -EALREADY Socket already connected.; -ENOTCONN Service in bad state.; -ECONNREFUSED Connection refused.; -EOVERFLOW Value too large for defined data type.; -EBADMSG Not a data message.

References mqtt_module::callback, mqtt_module::client, MQTT_CALLBACK_PUBLISHED, MQTTPublish(), NULL, MQTTMessage::payload, MQTTMessage::payloadlen, MQTTMessage::qos, and MQTTMessage::retained.

Referenced by check_usart_buffer(), and PROCESS_THREAD().

int mqtt_register_callback	(	struct mqtt_module *const	module,
		mqtt_callback_t	callback
	)

Register and enable the callback.

Parameters

[in]	module_inst	Instance of MQTT module.
[in]	callback	Callback entry for the MQTT module.

Returns: 0 Function succeeded; -ENOENT No such address.; -EINVAL Invalid argument.; -ENOSPC No space left on device.; -EIO Device was occurred error due to unknown exception.; -EDESTADDRREQ Destination address required.; -ECONNRESET Connection reset by peer.; -EAGAIN Try again.; -EBUSY Device or resource busy.; -EADDRINUSE Address already in use.; -EALREADY Socket already connected.; -ENOTCONN Service in bad state.; -ECONNREFUSED Connection refused.; -EOVERFLOW Value too large for defined data type.; -EBADMSG Not a data message.

References callback, mqtt_module::callback, FAILURE, and SUCCESS.

Referenced by configure_mqtt().

void mqtt_socket_event_handler	(	SOCKET	sock,
		uint8_t	msg_type,
		void *	msg_data
	)

Event handler of socket event.

Parameters

[in]	sock	Socket descriptor.
[in]	msg_type	Event type.
[in]	msg_data	Structure of socket event.

References tcpClientSocketEventHandler().

Referenced by socket_event_handler().

void mqtt_socket_resolve_handler	(	uint8_t *	doamin_name,
		uint32_t	server_ip
	)

Event handler of gethostbyname.

Parameters

[in]	doamin_name	Domain name.
[in]	server_ip	Server IP.

References dnsResolveCallback().

Referenced by socket_resolve_handler().

int mqtt_subscribe	(	struct mqtt_module *const	module,
		const char *	topic,
		uint8_t	qos,
		messageHandler	msgHandler
	)

Send subscribe message to MQTT broker server.

If operation of this function is complete, MQTT_CALLBACK_SUBSCRIBED event will be sent through MQTT callback.

Parameters

[in]	module_inst	Instance of MQTT module.
[in]	topic	A topic which will be received.
[in]	qos	QOS level of received publish message.

Returns: 0 Function succeeded; -ENOENT No such address.; -EINVAL Invalid argument.; -ENOSPC No space left on device.; -EIO Device was occurred error due to unknown exception.; -EDESTADDRREQ Destination address required.; -ECONNRESET Connection reset by peer.; -EAGAIN Try again.; -EBUSY Device or resource busy.; -EADDRINUSE Address already in use.; -EALREADY Socket already connected.; -ENOTCONN Service in bad state.; -ECONNREFUSED Connection refused.; -EOVERFLOW Value too large for defined data type.; -EBADMSG Not a data message.

References mqtt_module::callback, mqtt_module::client, MQTT_CALLBACK_SUBSCRIBED, MQTTSubscribe(), and NULL.

Referenced by mqtt_callback(), and PROCESS_THREAD().

int mqtt_unregister_callback ( struct mqtt_module *const module )

Unregister callback.

Parameters

[in] module_inst Instance of MQTT module.

Returns: 0 Function succeeded; -ENOENT No such address.; -EINVAL Invalid argument.; -ENOSPC No space left on device.; -EIO Device was occurred error due to unknown exception.; -EDESTADDRREQ Destination address required.; -ECONNRESET Connection reset by peer.; -EAGAIN Try again.; -EBUSY Device or resource busy.; -EADDRINUSE Address already in use.; -EALREADY Socket already connected.; -ENOTCONN Service in bad state.; -ECONNREFUSED Connection refused.; -EOVERFLOW Value too large for defined data type.; -EBADMSG Not a data message.

References mqtt_module::callback, FAILURE, NULL, and SUCCESS.

int mqtt_unsubscribe	(	struct mqtt_module *const	module,
		const char *	topic
	)

Send unsubscribe message to MQTT broker server.

If operation of this function is complete, MQTT_CALLBACK_UNSUBSCRIBED event will be sent through MQTT callback.

Parameters

[in]	module_inst	Instance of MQTT module.
[in]	topic	A topic that want to be removed.

Returns: 0 Function succeeded; -ENOENT No such address.; -EINVAL Invalid argument.; -ENOSPC No space left on device.; -EIO Device was occurred error due to unknown exception.; -EDESTADDRREQ Destination address required.; -ECONNRESET Connection reset by peer.; -EAGAIN Try again.; -EBUSY Device or resource busy.; -EADDRINUSE Address already in use.; -EALREADY Socket already connected.; -ENOTCONN Service in bad state.; -ECONNREFUSED Connection refused.; -EOVERFLOW Value too large for defined data type.; -EBADMSG Not a data message.

References mqtt_module::callback, mqtt_module::client, MQTT_CALLBACK_SUBSCRIBED, MQTTUnsubscribe(), and NULL.

int mqtt_yield	(	struct mqtt_module *	module,
		int	timeout_ms
	)

Poll for published frames.

Parameters

[in]	module_inst	Instance of MQTT module.
[in]	timeout_ms	time limit for polling.

Returns: 0 Function succeeded; -ENOENT No such address.; -EINVAL Invalid argument.; -ENOSPC No space left on device.; -EIO Device was occurred error due to unknown exception.; -EDESTADDRREQ Destination address required.; -ECONNRESET Connection reset by peer.; -EAGAIN Try again.; -EBUSY Device or resource busy.; -EADDRINUSE Address already in use.; -EALREADY Socket already connected.; -ENOTCONN Service in bad state.; -ECONNREFUSED Connection refused.; -EOVERFLOW Value too large for defined data type.; -EBADMSG Not a data message.

References mqtt_module::client, and MQTTYield().

Referenced by main().

struct mqtt_client_pool mqttClientPool[MQTT_MAX_CLIENTS]

Static Client Pool Allocation.

You are permitted to use the software and its derivatives with Microchip products.

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Referenced by isMQTTSocket().

Microchip® Advanced Software Framework

Data Structures

Typedefs

Enumerations

Functions

Variables