include/net/mqtt.h - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 /*
  * Copyright (c) 2016 Intel Corporation
  *
  * SPDX-License-Identifier: Apache-2.0
  */

 #ifndef _MQTT_H_
 #define _MQTT_H_

 #include <net/mqtt_types.h>
 #include <net/net_context.h>
 #include <net/net_app.h>

 #ifdef __cplusplus
 extern "C" {
 #endif

 /**
  * @brief MQTT library
  * @defgroup mqtt MQTT library
  * @ingroup networking
  * @{
  */

 /**
  * MQTT application type
  */
 enum mqtt_app {
 	/** Publisher and Subscriber application */
 	MQTT_APP_PUBLISHER_SUBSCRIBER,
 	/** Publisher only application */
 	MQTT_APP_PUBLISHER,
 	/** Subscriber only application */
 	MQTT_APP_SUBSCRIBER,
 	/** MQTT Server */
 	MQTT_APP_SERVER
 };

 /**
  * MQTT context structure
  *
  * @details Context structure for the MQTT high-level API with support for QoS.
  *
  * This API is designed for asynchronous operation, so callbacks are
  * executed when some events must be addressed outside the MQTT routines.
  * Those events are triggered by the reception or transmission of MQTT messages
  * and are defined by the MQTT v3.1.1 spec, see:
  *
  * http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/mqtt-v3.1.1.html
  *
  * For example, assume that Zephyr is operating as a MQTT_APP_SUBSCRIBER, so it
  * may receive the MQTT PUBLISH and MQTT PUBREL (QoS2) messages. Once the
  * messages are parsed and validated, the #publish_rx callback is executed.
  *
  * Internally, the #publish_rx callback must store the #mqtt_publish_msg message
  * when a MQTT PUBLISH msg is received. When a MQTT PUBREL message is received,
  * the application must evaluate if the PUBREL's Packet Identifier matches a
  * previous received MQTT PUBLISH message. In this case, the user may provide a
  * collection of #mqtt_publish_msg structs (array of structs) to store those
  * messages.
  *
  * <b>NOTE: The application (and not the API) is in charge of keeping track of
  * the state of the received and sent messages.</b>
  */
 struct mqtt_ctx {
 	/** Net app context structure */
 	struct net_app_ctx net_app_ctx;
 	s32_t net_init_timeout;
 	s32_t net_timeout;

 	/** Connectivity */
 	char *peer_addr_str;
 	u16_t peer_port;

 #if defined(CONFIG_MQTT_LIB_TLS)
 	/** TLS parameters */
 	u8_t *request_buf;
 	size_t request_buf_len;
 	u8_t *personalization_data;
 	size_t personalization_data_len;
 	char *cert_host;

 	/** TLS thread parameters */
 	struct k_mem_pool *tls_mem_pool;
 	k_thread_stack_t *tls_stack;
 	size_t tls_stack_size;

 	/** TLS callback */
 	net_app_ca_cert_cb_t cert_cb;
 	net_app_entropy_src_cb_t entropy_src_cb;

 	/** TLS handshake */
 	struct k_sem tls_hs_wait;
 	s32_t tls_hs_timeout;
 #endif

 	/** Callback executed when a MQTT CONNACK msg is received and validated.
 	 * If this function pointer is not used, must be set to NULL.
 	 */
 	void (*connect)(struct mqtt_ctx *ctx);

 	/** Callback executed when a MQTT DISCONNECT msg is sent.
 	 * If this function pointer is not used, must be set to NULL.
 	 */
 	void (*disconnect)(struct mqtt_ctx *ctx);

 	/** Callback executed when a #MQTT_APP_PUBLISHER application receives
 	 * a MQTT PUBxxxx msg.
 	 * If type is MQTT_PUBACK, MQTT_PUBCOMP or MQTT_PUBREC, this callback
 	 * must return 0 if pkt_id matches the packet id of a previously
 	 * received MQTT_PUBxxx message. If this callback returns 0, the caller
 	 * will continue.
 	 * Any other value will stop the QoS handshake and the caller will
 	 * return -EINVAL. The application must discard all the messages
 	 * already processed.
 	 *
 	 * <b>Note: this callback must be not NULL</b>
 	 *
 	 * @param [in] ctx MQTT context
 	 * @param [in] pkt_id Packet Identifier for the input MQTT msg
 	 * @param [in] type Packet type
 	 */
 	int (*publish_tx)(struct mqtt_ctx *ctx, u16_t pkt_id,
 			  enum mqtt_packet type);

 	/** Callback executed when a MQTT_APP_SUBSCRIBER,
 	 * MQTT_APP_PUBLISHER_SUBSCRIBER or MQTT_APP_SERVER applications receive
 	 * a MQTT PUBxxxx msg. If this callback returns 0, the caller will
 	 * continue. If type is MQTT_PUBREL this callback must return 0 if
 	 * pkt_id matches the packet id of a previously received MQTT_PUBxxx
 	 * message. Any other value will stop the QoS handshake and the caller
 	 * will return -EINVAL
 	 *
 	 * <b>Note: this callback must be not NULL</b>
 	 *
 	 * @param [in] ctx MQTT context
 	 * @param [in] msg Publish message, this parameter is only used
 	 *                 when the type is MQTT_PUBLISH
 	 * @param [in] pkt_id Packet Identifier for the input msg
 	 * @param [in] type Packet type
 	 */
 	int (*publish_rx)(struct mqtt_ctx *ctx, struct mqtt_publish_msg *msg,
 			  u16_t pkt_id, enum mqtt_packet type);

 	/** Callback executed when a MQTT_APP_SUBSCRIBER or
 	 * MQTT_APP_PUBLISHER_SUBSCRIBER receives the MQTT SUBACK message
 	 * If this callback returns 0, the caller will continue. Any other
 	 * value will make the caller return -EINVAL.
 	 *
 	 * <b>Note: this callback must be not NULL</b>
 	 *
 	 * @param [in] ctx MQTT context
 	 * @param [in] pkt_id Packet Identifier for the MQTT SUBACK msg
 	 * @param [in] items Number of elements in the qos array
 	 * @param [in] qos Array of QoS values
 	 */
 	int (*subscribe)(struct mqtt_ctx *ctx, u16_t pkt_id,
 			 u8_t items, enum mqtt_qos qos[]);

 	/** Callback executed when a MQTT_APP_SUBSCRIBER or
 	 * MQTT_APP_PUBLISHER_SUBSCRIBER receives the MQTT UNSUBACK message
 	 * If this callback returns 0, the caller will continue. Any other value
 	 * will make the caller return -EINVAL
 	 *
 	 * <b>Note: this callback must be not NULL</b>
 	 *
 	 * @param [in] ctx	MQTT context
 	 * @param [in] pkt_id	Packet Identifier for the MQTT SUBACK msg
 	 */
 	int (*unsubscribe)(struct mqtt_ctx *ctx, u16_t pkt_id);

 	/** Callback executed when an incoming message doesn't pass the
 	 * validation stage. This callback may be NULL.
 	 * The pkt_type variable may be set to MQTT_INVALID, if the parsing
 	 * stage is aborted before determining the MQTT msg packet type.
 	 *
 	 * @param [in] ctx	MQTT context
 	 * @param [in] pkt_type	MQTT Packet type
 	 */
 	void (*malformed)(struct mqtt_ctx *ctx, u16_t pkt_type);

 	/* Internal use only */
 	int (*rcv)(struct mqtt_ctx *ctx, struct net_pkt *);

 	/** Application type, see: enum mqtt_app */
 	u8_t app_type;

 	/* Clean session is also part of the MQTT CONNECT msg, however app
 	 * behavior is influenced by this parameter, so we keep a copy here
 	 */
 	/** MQTT Clean Session parameter */
 	u8_t clean_session:1;

 	/** 1 if the MQTT application is connected and 0 otherwise */
 	u8_t connected:1;
 };

 /**
  * Initializes the MQTT context structure
  *
  * @param ctx MQTT context structure
  * @param app_type See enum mqtt_app
  * @retval 0 always
  */
 int mqtt_init(struct mqtt_ctx *ctx, enum mqtt_app app_type);

 /**
  * Release the MQTT context structure
  *
  * @param ctx MQTT context structure
  * @retval 0 on success, and <0 if error
  */
 int mqtt_close(struct mqtt_ctx *ctx);

 /**
  * Connect to an MQTT broker
  *
  * @param ctx MQTT context structure
  * @retval 0 on success, and <0 if error
  */

 int mqtt_connect(struct mqtt_ctx *ctx);

 /**
  * Sends the MQTT CONNECT message
  *
  * @param [in] ctx MQTT context structure
  * @param [in] msg MQTT CONNECT msg
  *
  * @retval 0 on success
  * @retval -EIO
  * @retval -ENOMEM
  * @retval -EINVAL
  */
 int mqtt_tx_connect(struct mqtt_ctx *ctx, struct mqtt_connect_msg *msg);

 /**
  * Send the MQTT DISCONNECT message
  *
  * @param [in] ctx MQTT context structure
  *
  * @retval 0 on success
  * @retval -EIO
  * @retval -ENOMEM
  * @retval -EINVAL
  */
 int mqtt_tx_disconnect(struct mqtt_ctx *ctx);

 /**
  * Sends the MQTT PUBACK message with the given packet id
  *
  * @param [in] ctx MQTT context structure
  * @param [in] id MQTT Packet Identifier
  *
  * @retval 0 on success
  * @retval -EINVAL
  * @retval -ENOMEM
  * @retval -EIO
  */
 int mqtt_tx_puback(struct mqtt_ctx *ctx, u16_t id);

 /**
  * Sends the MQTT PUBCOMP message with the given packet id
  *
  * @param [in] ctx MQTT context structure
  * @param [in] id MQTT Packet Identifier
  *
  * @retval 0 on success
  * @retval -EINVAL
  * @retval -ENOMEM
  * @retval -EIO
  */
 int mqtt_tx_pubcomp(struct mqtt_ctx *ctx, u16_t id);

 /**
  * Sends the MQTT PUBREC message with the given packet id
  *
  * @param [in] ctx MQTT context structure
  * @param [in] id MQTT Packet Identifier
  * @retval 0 on success
  * @retval -EINVAL
  * @retval -ENOMEM
  * @retval -EIO
  */
 int mqtt_tx_pubrec(struct mqtt_ctx *ctx, u16_t id);

 /**
  * Sends the MQTT PUBREL message with the given packet id
  *
  * @param [in] ctx MQTT context structure
  * @param [in] id MQTT Packet Identifier
  *
  * @retval 0 on success
  * @retval -EINVAL
  * @retval -ENOMEM
  * @retval -EIO
  */
 int mqtt_tx_pubrel(struct mqtt_ctx *ctx, u16_t id);

 /**
  * Sends the MQTT PUBLISH message
  *
  * @param [in] ctx MQTT context structure
  * @param [in] msg MQTT PUBLISH msg
  *
  * @retval 0 on success
  * @retval -EINVAL
  * @retval -ENOMEM
  * @retval -EIO
  */
 int mqtt_tx_publish(struct mqtt_ctx *ctx, struct mqtt_publish_msg *msg);

 /**
  * Sends the MQTT PINGREQ message
  *
  * @param [in] ctx MQTT context structure
  *
  * @retval 0 on success
  * @retval -EINVAL
  * @retval -ENOMEM
  * @retval -EIO
  */
 int mqtt_tx_pingreq(struct mqtt_ctx *ctx);

 /**
  * Sends the MQTT SUBSCRIBE message
  *
  * @param [in] ctx MQTT context structure
  * @param [in] pkt_id Packet identifier for the MQTT SUBSCRIBE msg
  * @param [in] items Number of elements in 'topics' and 'qos' arrays
  * @param [in] topics Array of 'items' elements containing C strings.
  *                    For example: {"sensors", "lights", "doors"}
  * @param [in] qos Array of 'items' elements containing MQTT QoS values:
  *                 MQTT_QoS0, MQTT_QoS1, MQTT_QoS2. For example for the 'topics'
  *                 array above the following QoS may be used: {MQTT_QoS0,
  *                 MQTT_QoS2, MQTT_QoS1}, indicating that the subscription to
  *                 'lights' must be done with MQTT_QoS2
  *
  * @retval 0 on success
  * @retval -EINVAL
  * @retval -ENOMEM
  * @retval -EIO
  */
 int mqtt_tx_subscribe(struct mqtt_ctx *ctx, u16_t pkt_id, u8_t items,
 		      const char *topics[], const enum mqtt_qos qos[]);

 /**
  * Sends the MQTT UNSUBSCRIBE message
  *
  * @param [in] ctx MQTT context structure
  * @param [in] pkt_id Packet identifier for the MQTT UNSUBSCRIBE msg
  * @param [in] items Number of elements in the 'topics' array
  * @param [in] topics Array of 'items' elements containing C strings
  *
  * @retval 0 on success
  * @retval -EINVAL
  * @retval -ENOMEM
  * @retval -EIO
  */
 int mqtt_tx_unsubscribe(struct mqtt_ctx *ctx, u16_t pkt_id, u8_t items,
 			const char *topics[]);


 /**
  * Parses and validates the MQTT CONNACK msg
  *
  * @param [in] ctx MQTT context structure
  * @param [in] rx Data buffer
  * @param [in] clean_session MQTT clean session parameter
  *
  * @retval 0 on success
  * @retval -EINVAL
  */
 int mqtt_rx_connack(struct mqtt_ctx *ctx, struct net_buf *rx,
 		    int clean_session);

 /**
  * Parses and validates the MQTT PUBACK message
  *
  * @param [in] ctx MQTT context structure
  * @param [in] rx Data buffer
  *
  * @retval 0 on success
  * @retval -EINVAL
  */
 int mqtt_rx_puback(struct mqtt_ctx *ctx, struct net_buf *rx);

 /**
  * Parses and validates the MQTT PUBCOMP message
  *
  * @param [in] ctx MQTT context structure
  * @param [in] rx Data buffer
  *
  * @retval 0 on success
  * @retval -EINVAL
  */
 int mqtt_rx_pubcomp(struct mqtt_ctx *ctx, struct net_buf *rx);

 /**
  * Parses and validates the MQTT PUBREC message
  *
  * @param [in] ctx MQTT context structure
  * @param [in] rx Data buffer
  *
  * @retval 0 on success
  * @retval -EINVAL
  */
 int mqtt_rx_pubrec(struct mqtt_ctx *ctx, struct net_buf *rx);

 /**
  * Parses and validates the MQTT PUBREL message
  *
  * @param [in] ctx MQTT context structure
  * @param [in] rx Data buffer
  *
  * @retval 0 on success
  * @retval -EINVAL
  */
 int mqtt_rx_pubrel(struct mqtt_ctx *ctx, struct net_buf *rx);

 /**
  * Parses the MQTT PINGRESP message
  *
  * @param [in] ctx MQTT context structure
  * @param [in] rx Data buffer
  *
  * @retval 0 on success
  * @retval -EINVAL
  */
 int mqtt_rx_pingresp(struct mqtt_ctx *ctx, struct net_buf *rx);

 /**
  * Parses the MQTT SUBACK message
  *
  * @param [in] ctx MQTT context structure
  * @param [in] rx Data buffer
  *
  * @retval 0 on success
  * @retval -EINVAL
  */
 int mqtt_rx_suback(struct mqtt_ctx *ctx, struct net_buf *rx);

 /**
  * Parses the MQTT UNSUBACK message
  *
  * @param [in] ctx MQTT context structure
  * @param [in] rx Data buffer
  *
  * @retval 0 on success
  * @retval -EINVAL
  */
 int mqtt_rx_unsuback(struct mqtt_ctx *ctx, struct net_buf *rx);

 /**
  * Parses the MQTT PUBLISH message
  *
  * @param [in] ctx MQTT context structure
  * @param [in] rx Data buffer
  *
  * @retval 0 on success
  * @retval -EINVAL
  * @retval -ENOMEM
  */
 int mqtt_rx_publish(struct mqtt_ctx *ctx, struct net_buf *rx);

 /**
  * @}
  */

 #ifdef __cplusplus
 }
 #endif

 #endif /* _MQTT_H_ */
	/*
	* Copyright (c) 2016 Intel Corporation
	*
	* SPDX-License-Identifier: Apache-2.0
	*/

	#ifndef _MQTT_H_
	#define _MQTT_H_

	#include <net/mqtt_types.h>
	#include <net/net_context.h>
	#include <net/net_app.h>

	#ifdef __cplusplus
	extern "C" {
	#endif

	/**
	* @brief MQTT library
	* @defgroup mqtt MQTT library
	* @ingroup networking
	* @{
	*/

	/**
	* MQTT application type
	*/
	enum mqtt_app {
	/** Publisher and Subscriber application */
	MQTT_APP_PUBLISHER_SUBSCRIBER,
	/** Publisher only application */
	MQTT_APP_PUBLISHER,
	/** Subscriber only application */
	MQTT_APP_SUBSCRIBER,
	/** MQTT Server */
	MQTT_APP_SERVER
	};

	/**
	* MQTT context structure
	*
	* @details Context structure for the MQTT high-level API with support for QoS.
	*
	* This API is designed for asynchronous operation, so callbacks are
	* executed when some events must be addressed outside the MQTT routines.
	* Those events are triggered by the reception or transmission of MQTT messages
	* and are defined by the MQTT v3.1.1 spec, see:
	*
	* http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/mqtt-v3.1.1.html
	*
	* For example, assume that Zephyr is operating as a MQTT_APP_SUBSCRIBER, so it
	* may receive the MQTT PUBLISH and MQTT PUBREL (QoS2) messages. Once the
	* messages are parsed and validated, the #publish_rx callback is executed.
	*
	* Internally, the #publish_rx callback must store the #mqtt_publish_msg message
	* when a MQTT PUBLISH msg is received. When a MQTT PUBREL message is received,
	* the application must evaluate if the PUBREL's Packet Identifier matches a
	* previous received MQTT PUBLISH message. In this case, the user may provide a
	* collection of #mqtt_publish_msg structs (array of structs) to store those
	* messages.
	*
	* <b>NOTE: The application (and not the API) is in charge of keeping track of
	* the state of the received and sent messages.</b>
	*/
	struct mqtt_ctx {
	/** Net app context structure */
	struct net_app_ctx net_app_ctx;
	s32_t net_init_timeout;
	s32_t net_timeout;

	/** Connectivity */
	char *peer_addr_str;
	u16_t peer_port;

	#if defined(CONFIG_MQTT_LIB_TLS)
	/** TLS parameters */
	u8_t *request_buf;
	size_t request_buf_len;
	u8_t *personalization_data;
	size_t personalization_data_len;
	char *cert_host;

	/** TLS thread parameters */
	struct k_mem_pool *tls_mem_pool;
	k_thread_stack_t *tls_stack;
	size_t tls_stack_size;

	/** TLS callback */
	net_app_ca_cert_cb_t cert_cb;
	net_app_entropy_src_cb_t entropy_src_cb;

	/** TLS handshake */
	struct k_sem tls_hs_wait;
	s32_t tls_hs_timeout;
	#endif

	/** Callback executed when a MQTT CONNACK msg is received and validated.
	* If this function pointer is not used, must be set to NULL.
	*/
	void (connect)(struct mqtt_ctx ctx);

	/** Callback executed when a MQTT DISCONNECT msg is sent.
	* If this function pointer is not used, must be set to NULL.
	*/
	void (disconnect)(struct mqtt_ctx ctx);

	/** Callback executed when a #MQTT_APP_PUBLISHER application receives
	* a MQTT PUBxxxx msg.
	* If type is MQTT_PUBACK, MQTT_PUBCOMP or MQTT_PUBREC, this callback
	* must return 0 if pkt_id matches the packet id of a previously
	* received MQTT_PUBxxx message. If this callback returns 0, the caller
	* will continue.
	* Any other value will stop the QoS handshake and the caller will
	* return -EINVAL. The application must discard all the messages
	* already processed.
	*
	* <b>Note: this callback must be not NULL</b>
	*
	* @param [in] ctx MQTT context
	* @param [in] pkt_id Packet Identifier for the input MQTT msg
	* @param [in] type Packet type
	*/
	int (publish_tx)(struct mqtt_ctx ctx, u16_t pkt_id,
	enum mqtt_packet type);

	/** Callback executed when a MQTT_APP_SUBSCRIBER,
	* MQTT_APP_PUBLISHER_SUBSCRIBER or MQTT_APP_SERVER applications receive
	* a MQTT PUBxxxx msg. If this callback returns 0, the caller will
	* continue. If type is MQTT_PUBREL this callback must return 0 if
	* pkt_id matches the packet id of a previously received MQTT_PUBxxx
	* message. Any other value will stop the QoS handshake and the caller
	* will return -EINVAL
	*
	* <b>Note: this callback must be not NULL</b>
	*
	* @param [in] ctx MQTT context
	* @param [in] msg Publish message, this parameter is only used
	* when the type is MQTT_PUBLISH
	* @param [in] pkt_id Packet Identifier for the input msg
	* @param [in] type Packet type
	*/
	int (publish_rx)(struct mqtt_ctx ctx, struct mqtt_publish_msg *msg,
	u16_t pkt_id, enum mqtt_packet type);

	/** Callback executed when a MQTT_APP_SUBSCRIBER or
	* MQTT_APP_PUBLISHER_SUBSCRIBER receives the MQTT SUBACK message
	* If this callback returns 0, the caller will continue. Any other
	* value will make the caller return -EINVAL.
	*
	* <b>Note: this callback must be not NULL</b>
	*
	* @param [in] ctx MQTT context
	* @param [in] pkt_id Packet Identifier for the MQTT SUBACK msg
	* @param [in] items Number of elements in the qos array
	* @param [in] qos Array of QoS values
	*/
	int (subscribe)(struct mqtt_ctx ctx, u16_t pkt_id,
	u8_t items, enum mqtt_qos qos[]);

	/** Callback executed when a MQTT_APP_SUBSCRIBER or
	* MQTT_APP_PUBLISHER_SUBSCRIBER receives the MQTT UNSUBACK message
	* If this callback returns 0, the caller will continue. Any other value
	* will make the caller return -EINVAL
	*
	* <b>Note: this callback must be not NULL</b>
	*
	* @param [in] ctx MQTT context
	* @param [in] pkt_id Packet Identifier for the MQTT SUBACK msg
	*/
	int (unsubscribe)(struct mqtt_ctx ctx, u16_t pkt_id);

	/** Callback executed when an incoming message doesn't pass the
	* validation stage. This callback may be NULL.
	* The pkt_type variable may be set to MQTT_INVALID, if the parsing
	* stage is aborted before determining the MQTT msg packet type.
	*
	* @param [in] ctx MQTT context
	* @param [in] pkt_type MQTT Packet type
	*/
	void (malformed)(struct mqtt_ctx ctx, u16_t pkt_type);

	/* Internal use only */
	int (rcv)(struct mqtt_ctx ctx, struct net_pkt *);

	/** Application type, see: enum mqtt_app */
	u8_t app_type;

	/* Clean session is also part of the MQTT CONNECT msg, however app
	* behavior is influenced by this parameter, so we keep a copy here
	*/
	/** MQTT Clean Session parameter */
	u8_t clean_session:1;

	/** 1 if the MQTT application is connected and 0 otherwise */
	u8_t connected:1;
	};

	/**
	* Initializes the MQTT context structure
	*
	* @param ctx MQTT context structure
	* @param app_type See enum mqtt_app
	* @retval 0 always
	*/
	int mqtt_init(struct mqtt_ctx *ctx, enum mqtt_app app_type);

	/**
	* Release the MQTT context structure
	*
	* @param ctx MQTT context structure
	* @retval 0 on success, and <0 if error
	*/
	int mqtt_close(struct mqtt_ctx *ctx);

	/**
	* Connect to an MQTT broker
	*
	* @param ctx MQTT context structure
	* @retval 0 on success, and <0 if error
	*/

	int mqtt_connect(struct mqtt_ctx *ctx);

	/**
	* Sends the MQTT CONNECT message
	*
	* @param [in] ctx MQTT context structure
	* @param [in] msg MQTT CONNECT msg
	*
	* @retval 0 on success
	* @retval -EIO
	* @retval -ENOMEM
	* @retval -EINVAL
	*/
	int mqtt_tx_connect(struct mqtt_ctx ctx, struct mqtt_connect_msg msg);

	/**
	* Send the MQTT DISCONNECT message
	*
	* @param [in] ctx MQTT context structure
	*
	* @retval 0 on success
	* @retval -EIO
	* @retval -ENOMEM
	* @retval -EINVAL
	*/
	int mqtt_tx_disconnect(struct mqtt_ctx *ctx);

	/**
	* Sends the MQTT PUBACK message with the given packet id
	*
	* @param [in] ctx MQTT context structure
	* @param [in] id MQTT Packet Identifier
	*
	* @retval 0 on success
	* @retval -EINVAL
	* @retval -ENOMEM
	* @retval -EIO
	*/
	int mqtt_tx_puback(struct mqtt_ctx *ctx, u16_t id);

	/**
	* Sends the MQTT PUBCOMP message with the given packet id
	*
	* @param [in] ctx MQTT context structure
	* @param [in] id MQTT Packet Identifier
	*
	* @retval 0 on success
	* @retval -EINVAL
	* @retval -ENOMEM
	* @retval -EIO
	*/
	int mqtt_tx_pubcomp(struct mqtt_ctx *ctx, u16_t id);

	/**
	* Sends the MQTT PUBREC message with the given packet id
	*
	* @param [in] ctx MQTT context structure
	* @param [in] id MQTT Packet Identifier
	* @retval 0 on success
	* @retval -EINVAL
	* @retval -ENOMEM
	* @retval -EIO
	*/
	int mqtt_tx_pubrec(struct mqtt_ctx *ctx, u16_t id);

	/**
	* Sends the MQTT PUBREL message with the given packet id
	*
	* @param [in] ctx MQTT context structure
	* @param [in] id MQTT Packet Identifier
	*
	* @retval 0 on success
	* @retval -EINVAL
	* @retval -ENOMEM
	* @retval -EIO
	*/
	int mqtt_tx_pubrel(struct mqtt_ctx *ctx, u16_t id);

	/**
	* Sends the MQTT PUBLISH message
	*
	* @param [in] ctx MQTT context structure
	* @param [in] msg MQTT PUBLISH msg
	*
	* @retval 0 on success
	* @retval -EINVAL
	* @retval -ENOMEM
	* @retval -EIO
	*/
	int mqtt_tx_publish(struct mqtt_ctx ctx, struct mqtt_publish_msg msg);

	/**
	* Sends the MQTT PINGREQ message
	*
	* @param [in] ctx MQTT context structure
	*
	* @retval 0 on success
	* @retval -EINVAL
	* @retval -ENOMEM
	* @retval -EIO
	*/
	int mqtt_tx_pingreq(struct mqtt_ctx *ctx);

	/**
	* Sends the MQTT SUBSCRIBE message
	*
	* @param [in] ctx MQTT context structure
	* @param [in] pkt_id Packet identifier for the MQTT SUBSCRIBE msg
	* @param [in] items Number of elements in 'topics' and 'qos' arrays
	* @param [in] topics Array of 'items' elements containing C strings.
	* For example: {"sensors", "lights", "doors"}
	* @param [in] qos Array of 'items' elements containing MQTT QoS values:
	* MQTT_QoS0, MQTT_QoS1, MQTT_QoS2. For example for the 'topics'
	* array above the following QoS may be used: {MQTT_QoS0,
	* MQTT_QoS2, MQTT_QoS1}, indicating that the subscription to
	* 'lights' must be done with MQTT_QoS2
	*
	* @retval 0 on success
	* @retval -EINVAL
	* @retval -ENOMEM
	* @retval -EIO
	*/
	int mqtt_tx_subscribe(struct mqtt_ctx *ctx, u16_t pkt_id, u8_t items,
	const char *topics[], const enum mqtt_qos qos[]);

	/**
	* Sends the MQTT UNSUBSCRIBE message
	*
	* @param [in] ctx MQTT context structure
	* @param [in] pkt_id Packet identifier for the MQTT UNSUBSCRIBE msg
	* @param [in] items Number of elements in the 'topics' array
	* @param [in] topics Array of 'items' elements containing C strings
	*
	* @retval 0 on success
	* @retval -EINVAL
	* @retval -ENOMEM
	* @retval -EIO
	*/
	int mqtt_tx_unsubscribe(struct mqtt_ctx *ctx, u16_t pkt_id, u8_t items,
	const char *topics[]);


	/**
	* Parses and validates the MQTT CONNACK msg
	*
	* @param [in] ctx MQTT context structure
	* @param [in] rx Data buffer
	* @param [in] clean_session MQTT clean session parameter
	*
	* @retval 0 on success
	* @retval -EINVAL
	*/
	int mqtt_rx_connack(struct mqtt_ctx ctx, struct net_buf rx,
	int clean_session);

	/**
	* Parses and validates the MQTT PUBACK message
	*
	* @param [in] ctx MQTT context structure
	* @param [in] rx Data buffer
	*
	* @retval 0 on success
	* @retval -EINVAL
	*/
	int mqtt_rx_puback(struct mqtt_ctx ctx, struct net_buf rx);

	/**
	* Parses and validates the MQTT PUBCOMP message
	*
	* @param [in] ctx MQTT context structure
	* @param [in] rx Data buffer
	*
	* @retval 0 on success
	* @retval -EINVAL
	*/
	int mqtt_rx_pubcomp(struct mqtt_ctx ctx, struct net_buf rx);

	/**
	* Parses and validates the MQTT PUBREC message
	*
	* @param [in] ctx MQTT context structure
	* @param [in] rx Data buffer
	*
	* @retval 0 on success
	* @retval -EINVAL
	*/
	int mqtt_rx_pubrec(struct mqtt_ctx ctx, struct net_buf rx);

	/**
	* Parses and validates the MQTT PUBREL message
	*
	* @param [in] ctx MQTT context structure
	* @param [in] rx Data buffer
	*
	* @retval 0 on success
	* @retval -EINVAL
	*/
	int mqtt_rx_pubrel(struct mqtt_ctx ctx, struct net_buf rx);

	/**
	* Parses the MQTT PINGRESP message
	*
	* @param [in] ctx MQTT context structure
	* @param [in] rx Data buffer
	*
	* @retval 0 on success
	* @retval -EINVAL
	*/
	int mqtt_rx_pingresp(struct mqtt_ctx ctx, struct net_buf rx);

	/**
	* Parses the MQTT SUBACK message
	*
	* @param [in] ctx MQTT context structure
	* @param [in] rx Data buffer
	*
	* @retval 0 on success
	* @retval -EINVAL
	*/
	int mqtt_rx_suback(struct mqtt_ctx ctx, struct net_buf rx);

	/**
	* Parses the MQTT UNSUBACK message
	*
	* @param [in] ctx MQTT context structure
	* @param [in] rx Data buffer
	*
	* @retval 0 on success
	* @retval -EINVAL
	*/
	int mqtt_rx_unsuback(struct mqtt_ctx ctx, struct net_buf rx);

	/**
	* Parses the MQTT PUBLISH message
	*
	* @param [in] ctx MQTT context structure
	* @param [in] rx Data buffer
	*
	* @retval 0 on success
	* @retval -EINVAL
	* @retval -ENOMEM
	*/
	int mqtt_rx_publish(struct mqtt_ctx ctx, struct net_buf rx);

	/**
	* @}
	*/

	#ifdef __cplusplus
	}
	#endif

	#endif /* _MQTT_H_ */