This application is an engine for MQTT v3.1. More...

Files
file	mqtt.c
	Implementation of the Contiki MQTT engine.

file	mqtt.h
	Header file for the Contiki MQTT engine.

Typedefs
typedef void(*	mqtt_event_callback_t) (struct mqtt_connection m, mqtt_event_t event, void data)
	MQTT event callback function. More...

Enumerations
enum	mqtt_event_t
	MQTT engine events.

Functions
mqtt_status_t	mqtt_register (struct mqtt_connection conn, struct process app_process, char *client_id, mqtt_event_callback_t event_callback, uint16_t max_segment_size)
	Initializes the MQTT engine. More...

mqtt_status_t	mqtt_connect (struct mqtt_connection conn, char host, uint16_t port, uint16_t keep_alive, uint8_t clean_session, struct mqtt_prop_list *prop_list)
	Connects to a MQTT broker. More...

void	mqtt_disconnect (struct mqtt_connection conn, struct mqtt_prop_list prop_list)
	Disconnects from a MQTT broker. More...

mqtt_status_t	mqtt_subscribe (struct mqtt_connection conn, uint16_t mid, char topic, mqtt_qos_level_t qos_level, mqtt_nl_en_t nl, mqtt_rap_en_t rap, mqtt_retain_handling_t ret_handling, struct mqtt_prop_list prop_list)
	Subscribes to a MQTT topic. More...

mqtt_status_t	mqtt_unsubscribe (struct mqtt_connection conn, uint16_t mid, char topic, struct mqtt_prop_list prop_list)
	Unsubscribes from a MQTT topic. More...

mqtt_status_t	mqtt_publish (struct mqtt_connection conn, uint16_t mid, char topic, uint8_t payload, uint32_t payload_size, mqtt_qos_level_t qos_level, mqtt_retain_t retain, uint8_t topic_alias, mqtt_topic_alias_en_t topic_alias_en, struct mqtt_prop_list *prop_list)
	Publish to a MQTT topic. More...

void	mqtt_set_username_password (struct mqtt_connection conn, char username, char *password)
	Set the user name and password for a MQTT client. More...

void	mqtt_set_last_will (struct mqtt_connection conn, char topic, char message, mqtt_qos_level_t qos, struct mqtt_prop_list will_props)
	Set the last will topic and message for a MQTT client. More...

mqtt_status_t	mqtt_auth (struct mqtt_connection conn, mqtt_auth_type_t auth_type, struct mqtt_prop_list prop_list)
	Send authentication message (MQTTv5-only). More...

Detailed Description

This application is an engine for MQTT v3.1.

It supports QoS Levels 0 and 1.

MQTT is a Client Server publish/subscribe messaging transport protocol. It is light weight, open, simple, and designed so as to be easy to implement. These characteristics make it ideal for use in many situations, including constrained environments such as for communication in Machine to Machine (M2M) and Internet of Things (IoT) contexts where a small code footprint is required and/or network bandwidth is at a premium.

The protocol runs over TCP/IP, more specifically tcp_socket. Its features include:

Use of the publish/subscribe message pattern which provides one-to-many message distribution and decoupling of applications.
A messaging transport that is agnostic to the content of the payload. Three qualities of service for message delivery: – "At most once" (0), where messages are delivered according to the best efforts of the operating environment. Message loss can occur. This level could be used, for example, with ambient sensor data where it does not matter if an individual reading is lost as the next one will be published soon after. –"At least once" (1), where messages are assured to arrive but duplicates can occur. – "Exactly once" (2), where message are assured to arrive exactly once. This level could be used, for example, with billing systems where duplicate or lost messages could lead to incorrect charges being applied. This QoS level is currently not supported in this implementation.
A small transport overhead and protocol exchanges minimized to reduce network traffic.
A mechanism, Last Will, to notify interested parties when an abnormal disconnection occurs.

The protocol specification and other useful information can be found here: http://mqtt.org

Typedef Documentation

◆ mqtt_event_callback_t

typedef void(* mqtt_event_callback_t) (struct mqtt_connection *m, mqtt_event_t event, void *data)

MQTT event callback function.

Parameters

m	A pointer to a MQTT connection
event	The event number
data	A user-defined pointer

The MQTT socket event callback function gets called whenever there is an event on a MQTT connection, such as the connection getting connected or closed.

Definition at line 499 of file mqtt.h.

Function Documentation

◆ mqtt_auth()

mqtt_status_t mqtt_auth	(	struct mqtt_connection *	conn,
		mqtt_auth_type_t	auth_type,
		struct mqtt_prop_list *	prop_list
	)

Send authentication message (MQTTv5-only).

Parameters

conn	A pointer to the MQTT connection.
auth_type	The type of auth to send (continue authentication or re-authentication).
prop_list	Output properties.

Returns: MQTT_STATUS_OK or some error status

This function send an MQTT authentication message.

Definition at line 2095 of file mqtt.c.

◆ mqtt_connect()

mqtt_status_t mqtt_connect	(	struct mqtt_connection *	conn,
		char *	host,
		uint16_t	port,
		uint16_t	keep_alive,
		uint8_t	clean_session,
		struct mqtt_prop_list *	prop_list
	)

Connects to a MQTT broker.

Parameters

conn	A pointer to the MQTT connection.
host	IP address of the broker to connect to.
port	Port of the broker to connect to, default is MQTT port is 1883.
keep_alive	Keep alive timer in seconds. Used by broker to handle client disc. Defines the maximum time interval between two messages from the client. Shall be min 1.5 x report interval.
clean_session	Request a new session and discard pending messages with QoS > 0, as well as client subscriptions
prop_list	Output properties (MQTTv5-only).

Returns: MQTT_STATUS_OK or an error status

This function connects to a MQTT broker.

Definition at line 1816 of file mqtt.c.

◆ mqtt_disconnect()

void mqtt_disconnect	(	struct mqtt_connection *	conn,
		struct mqtt_prop_list *	prop_list
	)

Disconnects from a MQTT broker.

Parameters

conn	A pointer to the MQTT connection.
prop_list	Output properties (MQTTv5-only).

This function disconnects from a MQTT broker.

Definition at line 1868 of file mqtt.c.

◆ mqtt_publish()

mqtt_status_t mqtt_publish	(	struct mqtt_connection *	conn,
		uint16_t *	mid,
		char *	topic,
		uint8_t *	payload,
		uint32_t	payload_size,
		mqtt_qos_level_t	qos_level,
		mqtt_retain_t	retain,
		uint8_t	topic_alias,
		mqtt_topic_alias_en_t	topic_alias_en,
		struct mqtt_prop_list *	prop_list
	)

Publish to a MQTT topic.

Parameters

conn	A pointer to the MQTT connection.
mid	A pointer to message ID.
topic	A pointer to the topic to subscribe to.
payload	A pointer to the topic payload.
payload_size	Payload size.
qos_level	Quality Of Service level to use. Currently supports 0, 1.
retain	If the RETAIN flag is set to 1, in a PUBLISH Packet sent by a Client to a Server, the Server MUST store the Application Message and its QoS, so that it can be delivered to future subscribers whose subscriptions match its topic name
topic_alias	Topic alias to send (MQTTv5-only).
topic_alias_en	Control whether or not to discard topic and only send topic alias s(MQTTv5-only).
prop_list	Output properties (MQTTv5-only).

Returns: MQTT_STATUS_OK or some error status

This function publishes to a topic on a MQTT broker.

Definition at line 1979 of file mqtt.c.

◆ mqtt_register()

mqtt_status_t mqtt_register	(	struct mqtt_connection *	conn,
		struct process *	app_process,
		char *	client_id,
		mqtt_event_callback_t	event_callback,
		uint16_t	max_segment_size
	)

Initializes the MQTT engine.

Parameters

conn	A pointer to the MQTT connection.
app_process	A pointer to the application process handling the MQTT connection.
client_id	A pointer to the MQTT client ID.
event_callback	Callback function responsible for handling the callback from MQTT engine.
max_segment_size	The TCP segment size to use for this MQTT/TCP connection.

Returns: MQTT_STATUS_OK or MQTT_STATUS_INVALID_ARGS_ERROR

This function initializes the MQTT engine and shall be called before any other MQTT function.

Definition at line 1777 of file mqtt.c.

◆ mqtt_set_last_will()

void mqtt_set_last_will	(	struct mqtt_connection *	conn,
		char *	topic,
		char *	message,
		mqtt_qos_level_t	qos,
		struct mqtt_prop_list *	will_props
	)

Set the last will topic and message for a MQTT client.

Parameters

conn	A pointer to the MQTT connection.
topic	A pointer to the Last Will topic.
message	A pointer to the Last Will message (payload).
qos	The desired QoS level.
will_props	Will message properties (MQTTv5-only).

This function sets clients Last Will topic and message (payload). If the Will Flag is set to 1 (using the function) this indicates that, if the Connect request is accepted, a Will Message MUST be stored on the Server and associated with the Network Connection. The Will Message MUST be published when the Network Connection is subsequently closed.

This functionality can be used to get notified that a device has disconnected from the broker.

Definition at line 2062 of file mqtt.c.

◆ mqtt_set_username_password()

void mqtt_set_username_password	(	struct mqtt_connection *	conn,
		char *	username,
		char *	password
	)

Set the user name and password for a MQTT client.

Parameters

conn	A pointer to the MQTT connection.
username	A pointer to the user name.
password	A pointer to the password.

This function sets clients user name and password to use when connecting to a MQTT broker.

Definition at line 2041 of file mqtt.c.

◆ mqtt_subscribe()

mqtt_status_t mqtt_subscribe	(	struct mqtt_connection *	conn,
		uint16_t *	mid,
		char *	topic,
		mqtt_qos_level_t	qos_level,
		mqtt_nl_en_t	nl,
		mqtt_rap_en_t	rap,
		mqtt_retain_handling_t	ret_handling,
		struct mqtt_prop_list *	prop_list
	)

Subscribes to a MQTT topic.

Parameters

conn	A pointer to the MQTT connection.
mid	A pointer to message ID.
topic	A pointer to the topic to subscribe to.
qos_level	Quality Of Service level to use. Currently supports 0, 1.
nl	No Local (MQTTv5-only).
rap	Retain As Published (MQTTv5-only).
ret_handling	Retain handling options (MQTTv5-only).
prop_list	Output properties (MQTTv5-only).

Returns: MQTT_STATUS_OK or some error status

This function subscribes to a topic on a MQTT broker.

Definition at line 1888 of file mqtt.c.

◆ mqtt_unsubscribe()

mqtt_status_t mqtt_unsubscribe	(	struct mqtt_connection *	conn,
		uint16_t *	mid,
		char *	topic,
		struct mqtt_prop_list *	prop_list
	)

Unsubscribes from a MQTT topic.

Parameters

conn	A pointer to the MQTT connection.
mid	A pointer to message ID.
topic	A pointer to the topic to unsubscribe from.
prop_list	Output properties (MQTTv5-only).

Returns: MQTT_STATUS_OK or some error status

This function unsubscribes from a topic on a MQTT broker.

Definition at line 1940 of file mqtt.c.

Files

Typedefs

Enumerations

Functions

Detailed Description

Typedef Documentation

◆ mqtt_event_callback_t

Function Documentation

◆ mqtt_auth()

◆ mqtt_connect()

◆ mqtt_disconnect()

◆ mqtt_publish()

◆ mqtt_register()

◆ mqtt_set_last_will()

◆ mqtt_set_username_password()

◆ mqtt_subscribe()

◆ mqtt_unsubscribe()