MQTT Client

MQTT Client library.

Example Usage

#include <proto/mqttclient.h>

mqtt_client_t *client = NULL;
char client_id[32];

/* set a client ID */
strcpy(client_id, "1234567890");
/* init new mqtt client */
client = mqtt_lease();
/* configure host */
mqtt_set_host(client, "broker.example.com");
/* configure port */
mqtt_set_port(client, "1883");
/* set client id */
mqtt_set_client_id(client, client_id);
/* configure session clean */
mqtt_set_clean_session(client, 1);
/* connect to broker */
mqtt_connect(client);
/* topic subscribe */
mqtt_subscribe(client, "topic1", QOS0, topic1_handler);

/* publish message */
mqtt_message_t msg;
memset(&msg, 0, sizeof(msg));
/* set payload */
msg.payload = "Test";
/* set QOS value */
msg.qos = 0;
/* publish */
mqtt_publish(client, "topic2", &msg);

API Reference

Header File

Source: include/proto/mqttclient.h

#include <proto/mqttclient.h>

Functions

const char *mqtt_set_client_id(mqtt_client_t *client, const char *id)

Set MQTT broker client id.

Parameters:

client – MQTT client handle
id – Client ID to set

Returns:

client id or NULL when error

const char *mqtt_set_user_name(mqtt_client_t *client, const char *username)

Set MQTT broker username.

Parameters:

client – MQTT client handle
username – Username to set

Returns:

username or NULL when error

const char *mqtt_set_password(mqtt_client_t *client, const char *password)

Set MQTT broker client ID.

Parameters:

client – MQTT client handle
password – Password to set

Returns:

password or NULL when error

const char *mqtt_set_host(mqtt_client_t *client, const char *host)

Set MQTT broker host name.

Parameters:

client – MQTT client handle
host – hostname to set

Returns:

hostname on success or NULL

const char *mqtt_set_port(mqtt_client_t *client, const char *port)

Set MQTT broker port.

Parameters:

client – MQTT client handle
port – Port to set

Returns:

Port value or NULL when error

const char *mqtt_set_ca(mqtt_client_t *client, const char *ca)

Set CA certificate.

Parameters:

client – MQTT client handle
ca – CA certificate in PEM format

Returns:

pointer to CA or NULL when error

int mqtt_set_client_cert(mqtt_client_t *client, char *cert)

Set client certificate.

Parameters:

client – MQTT client handle
cert – client certificate in PEM format

Returns:

0 on success, error code otherwise

int mqtt_set_client_prvkey(mqtt_client_t *client, char *key)

Set client private key.

Parameters:

client – MQTT client handle
key – client private key

Returns:

0 on success, error code otherwise

void *mqtt_set_reconnect_data(mqtt_client_t *client, void *arg)

Set custom user argument passed to reconnect hook handler.

Parameters:

client – MQTT client handle
arg – User argument

Returns:

user argument on success or NULL for error

uint16_t mqtt_set_keep_alive_interval(mqtt_client_t *client, uint16_t ka)

Set keep alive interval, default 30s.

Parameters:

client – MQTT client handle
ka – Keep alive interval in seconds

Returns:

current set value on success or 0 otherwise

uint32_t mqtt_set_will_flag(mqtt_client_t *client, uint32_t will_flag)

Enable or disable LWT message, default 0.

Parameters:

client – MQTT client handle
will_flag – Will flag, 1 to enable, 0 to disable

Returns:

current value of will flag

uint32_t mqtt_set_clean_session(mqtt_client_t *client, uint32_t clean_session)

Enable or disable MQTT clean session flag, default 0.

Parameters:

client – MQTT client handle
clean_session – clean session flag value, 0 - persistent session, 1 - non-persistent session

Returns:

current value of clean sesson flag

uint32_t mqtt_set_version(mqtt_client_t *client, uint32_t version)

Change MQTT version, default 4 (for MQTT 3.1.1)

Parameters:

client – MQTT client handle
version – version value

Returns:

current version value

uint32_t mqtt_set_cmd_timeout(mqtt_client_t *client, uint32_t timeout)

Set MQTT command timeout value, default 20000ms.

Parameters:

client – MQTT client handle
timeout – Timeout value in milliseconds

Returns:

current set timeout value

uint32_t mqtt_set_read_buf_size(mqtt_client_t *client, uint32_t bufsz)

set MQTT read payload buffer size, default 1024 bytes

Parameters:

client – MQTT client handle
bufsz – size of buffer in bytes

Returns:

current size on success, 0 on error

uint32_t mqtt_set_write_buf_size(mqtt_client_t *client, uint32_t bufsz)

Set MQTT write payload buffer size, default 1024 bytes.

Parameters:

client – MQTT client handle
bufsz – size of buffer in bytes

Returns:

current size on success, 0 on error

uint32_t mqtt_set_reconnect_try_duration(mqtt_client_t *client, uint32_t duration)

Set MQTT reconnect duration, default 1000ms.

Parameters:

client – MQTT client handle
duration – reconnect duration in millisecond

Returns:

current duration on success or 0 on error

reconnect_handler_t mqtt_set_reconnect_handler(mqtt_client_t *client, reconnect_handler_t fn)

Set MQTT socket reconnect hook.

Parameters:

client – MQTT client handle
fn – handler function to set

Returns:

handler function value on success, NULL on error

interceptor_handler_t mqtt_set_interceptor_handler(mqtt_client_t *client, interceptor_handler_t fn)

Set MQTT incoming message interceptor hook.

Parameters:

client – MQTT client handle
fn – handler function to set

Returns:

handler function value on success, NULL on error

mqtt_client_t *mqtt_lease(void)

Allocate and init a new MQTT client handle.

Note

only single MQTT connection is allowed on MT6261/MT2503 SoC

Returns:: MQTT client handle

int mqtt_release(mqtt_client_t *c)

release previously allocated MQTT client by mqtt_lease()

Parameters:: c – MQTT client handle
Returns:: 0 on success, error code otherwise mqtt_error_t

int mqtt_connect(mqtt_client_t *c)

Connect to MQTT broker.

Parameters:: c – MQTT client handle
Returns:: 0 on success, error code otherwise mqtt_error_t

int mqtt_disconnect(mqtt_client_t *c)

Disconnect from MQTT broker.

Parameters:: c – MQTT client handle
Returns:: 0 on success, error code otherwise mqtt_error_t

int mqtt_subscribe(mqtt_client_t *c, const char *topic_filter, mqtt_qos_t qos, message_handler_t msg_handler)

Subscribe to a topic.

Parameters:

c – MQTT client handle
topic_filter – Topic name
qos – Quality of service mqtt_qos_t
msg_handler – incoming message handler

Returns:

0 on success, error code otherwise mqtt_error_t

int mqtt_unsubscribe(mqtt_client_t *c, const char *topic_filter)

Unsubscribe a topic.

Parameters:

c – MQTT client handle
topic_filter – topic name

Returns:

0 on success, error code otherwise mqtt_error_t

int mqtt_publish(mqtt_client_t *c, const char *topic_filter, mqtt_message_t *msg)

Publish a message.

Parameters:

c – MQTT client handle
topic_filter – topic name
msg – Message to send mqtt_message_t

Returns:

0 on success, error code otherwise mqtt_error_t

int mqtt_set_will_options(mqtt_client_t *c, char *topic, mqtt_qos_t qos, uint8_t retained, char *message)

Set/change LWT options, this call will enable will flag if disabled.

Parameters:

c – MQTT client handle
topic – topic name
qos – Quality of service mqtt_qos_t
retained – retained flag
message – LWT message

Returns:

0 on success, error code otherwise mqtt_error_t

Structures

struct mqtt_message

MQTT Message payload information structure.

Public Members

mqtt_qos_t qos: Quality of service see mqtt_qos_t

uint8_t retained: flag for retained message

uint8_t dup: flag indicating duplicate message

uint16_t id: Message identifier

size_t payloadlen: Payload length

void *payload: Payload data

struct message_data

MQTT Message data structure.

Public Members

char topic_name[MQTT_TOPIC_LEN_MAX]: Topic name

mqtt_message_t *message: pointer to message payload

Macros

MQTT_TOPIC_LEN_MAX

mqtt.h

This file has been derived from mqttclient library by jiejie.

Type Definitions

typedef enum mqtt_error mqtt_error_t: MQTT error codes.

typedef enum mqtt_qos mqtt_qos_t: MQTT QOS Level.

typedef struct mqtt_message mqtt_message_t: MQTT Message payload information structure.

typedef struct message_data message_data_t: MQTT Message data structure.

typedef struct mqtt_client mqtt_client_t: mqtt_client forward definition

typedef void (*interceptor_handler_t)(void *client, message_data_t *msg): incoming message intercept handler

typedef void (*message_handler_t)(void *client, message_data_t *msg): Incoming message handler for assigned topic.

typedef void (*reconnect_handler_t)(void *client, void *reconnect_date): Reconnection hook, this function is called before reconnection.

Enumerations

enum mqtt_error

MQTT error codes.

Values:

enumerator MQTT_SSL_CERT_ERROR

enumerator MQTT_SOCKET_FAILED_ERROR

enumerator MQTT_SOCKET_UNKNOWN_HOST_ERROR

enumerator MQTT_SET_PUBLISH_DUP_FAILED_ERROR

enumerator MQTT_CLEAN_SESSION_ERROR

enumerator MQTT_ACK_NODE_IS_EXIST_ERROR

enumerator MQTT_ACK_HANDLER_NUM_TOO_MUCH_ERROR

enumerator MQTT_RESUBSCRIBE_ERROR

enumerator MQTT_SUBSCRIBE_ERROR

enumerator MQTT_SEND_PACKET_ERROR

enumerator MQTT_SERIALIZE_PUBLISH_ACK_PACKET_ERROR

enumerator MQTT_PUBLISH_PACKET_ERROR

enumerator MQTT_RECONNECT_TIMEOUT_ERROR

enumerator MQTT_SUBSCRIBE_NOT_ACK_ERROR

enumerator MQTT_NOT_CONNECT_ERROR

enumerator MQTT_SUBSCRIBE_ACK_PACKET_ERROR

enumerator MQTT_UNSUBSCRIBE_ACK_PACKET_ERROR

enumerator MQTT_PUBLISH_ACK_PACKET_ERROR

enumerator MQTT_PUBLISH_ACK_TYPE_ERROR

enumerator MQTT_PUBREC_PACKET_ERROR

enumerator MQTT_BUFFER_TOO_SHORT_ERROR

enumerator MQTT_NOTHING_TO_READ_ERROR

enumerator MQTT_SUBSCRIBE_QOS_ERROR

enumerator MQTT_BUFFER_OVERFLOW_ERROR

enumerator MQTT_CONNECT_FAILED_ERROR

enumerator MQTT_MEM_NOT_ENOUGH_ERROR

enumerator MQTT_NULL_VALUE_ERROR

enumerator MQTT_FAILED_ERROR

enumerator MQTT_SUCCESS_ERROR

enum mqtt_qos

MQTT QOS Level.

Values:

enumerator QOS0: Quality of Service level 0: message delivery at most once

enumerator QOS1: Quality of Service level 1: message delivery at least once

enumerator QOS2: Quality of Service level 2: message delivery exactly once

enumerator SUBFAIL