core_mqtt_serializer.c File Reference

Implements the user-facing functions in core_mqtt_serializer.h. More...

#include <string.h>
#include <assert.h>
#include <inttypes.h>
#include <stdbool.h>
#include "core_mqtt.h"
#include "core_mqtt_serializer.h"
#include "transport_interface.h"
#include "private/core_mqtt_serializer_private.h"
#include "core_mqtt_config_defaults.h"

Data Structures
struct	ConnackSeenFlags_t
	Tracks which CONNACK properties have been seen during deserialization, used to detect duplicates. More...

Macros
#define	MQTT_PACKET_CONNECT_HEADER_SIZE   ( 10U )
	Size of the fixed and variable header of a CONNECT packet.
#define	MQTT_PUBLISH_FLAG_RETAIN   ( 0 )
	MQTT PUBLISH retain flag.
#define	MQTT_PUBLISH_FLAG_QOS1   ( 1 )
	MQTT PUBLISH QoS1 flag.
#define	MQTT_PUBLISH_FLAG_QOS2   ( 2 )
	MQTT PUBLISH QoS2 flag.
#define	MQTT_PUBLISH_FLAG_DUP   ( 3 )
	MQTT PUBLISH duplicate flag.
#define	MQTT_PACKET_PINGREQ_SIZE   ( 2U )
	A PINGREQ packet is always 2 bytes in size, defined by MQTT 5.0 spec.
#define	MQTT_PACKET_CONNACK_SESSION_PRESENT_MASK   ( ( uint8_t ) 0x01U )
	The "Session Present" bit is always the lowest bit.
#define	MQTT_PACKET_SIMPLE_ACK_REMAINING_LENGTH   ( ( uint8_t ) 2 )
	Minimum Length of PUBACK, PUBREC, PUBREL, PUBCOMP Packets.
#define	MQTT_PACKET_PINGRESP_REMAINING_LENGTH   ( 0U )
	A PINGRESP packet always has a "Remaining length" of 0.
#define	MQTT_PACKET_CONNACK_MINIMUM_SIZE   ( 3U )
	Minimum number of bytes in the CONNACK Packet. CONNECT Acknowledge Flags 0 + 1 = 1 CONNECT Reason Code + 1 = 2 Property Length byte (min) + 1 = 3.

Functions
static void	serializePublishCommon (const MQTTPublishInfo_t *pPublishInfo, const MQTTPropBuilder_t *pPublishProperties, uint32_t remainingLength, uint16_t packetIdentifier, const MQTTFixedBuffer_t *pFixedBuffer, bool serializePayload)
	Serializes MQTT PUBLISH packet into the buffer provided.
static MQTTStatus_t	calculatePublishPacketSize (const MQTTPublishInfo_t *pPublishInfo, uint32_t *pRemainingLength, uint32_t *pPacketSize, uint32_t maxPacketSize, uint32_t publishPropertyLength)
	Calculates the packet size and remaining length of an MQTT PUBLISH packet.
static MQTTStatus_t	calculateSubscriptionPacketSize (const MQTTSubscribeInfo_t *pSubscriptionList, size_t subscriptionCount, uint32_t *pRemainingLength, uint32_t *pPacketSize, uint32_t subscribePropLen, uint32_t maxPacketSize, MQTTSubscriptionType_t subscriptionType)
	Calculates the packet size and remaining length of an MQTT SUBSCRIBE or UNSUBSCRIBE packet.
static MQTTStatus_t	validateSubscriptionSerializeParams (const MQTTSubscribeInfo_t *pSubscriptionList, size_t subscriptionCount, uint16_t packetId, uint32_t remainingLength, const MQTTFixedBuffer_t *pFixedBuffer)
	Validates parameters of MQTT_SerializeSubscribe or MQTT_SerializeUnsubscribe.
static void	serializeConnectPacket (const MQTTConnectInfo_t *pConnectInfo, const MQTTPublishInfo_t *pWillInfo, const MQTTPropBuilder_t *pConnectProperties, const MQTTPropBuilder_t *pWillProperties, uint32_t remainingLength, const MQTTFixedBuffer_t *pFixedBuffer)
	Serialize an MQTT CONNECT packet in the given buffer.
static void	logConnackResponse (uint8_t responseCode)
	Prints the appropriate message for the CONNACK response code if logs are enabled.
static uint32_t	remainingLengthEncodedSize (uint32_t length)
	Retrieve the size of the remaining length if it were to be encoded.
static uint32_t	getRemainingLength (TransportRecv_t recvFunc, NetworkContext_t *pNetworkContext)
	Retrieves and decodes the Remaining Length from the network interface by reading a single byte at a time.
static MQTTStatus_t	processRemainingLength (const uint8_t *pBuffer, const size_t *pIndex, MQTTPacketInfo_t *pIncomingPacket)
	Retrieves, decodes and stores the Remaining Length from the network interface by reading a single byte at a time.
static bool	incomingPacketValid (uint8_t packetType)
	Check if an incoming packet type is valid.
static MQTTStatus_t	checkPublishRemainingLength (uint32_t remainingLength, MQTTQoS_t qos, uint32_t qos0Minimum)
	Check the remaining length of an incoming PUBLISH packet against some value for QoS 0, or for QoS 1 and 2.
static MQTTStatus_t	processPublishFlags (uint8_t publishFlags, MQTTPublishInfo_t *pPublishInfo)
	Process the flags of an incoming PUBLISH packet.
static MQTTStatus_t	deserializeConnack (MQTTConnectionProperties_t *pConnackProperties, const MQTTPacketInfo_t *pIncomingPacket, bool *pSessionPresent, MQTTPropBuilder_t *pPropBuffer)
	Deserialize an MQTT CONNACK packet.
static MQTTStatus_t	readSubackStatus (size_t statusCount, const uint8_t *pStatusStart, MQTTReasonCodeInfo_t *pReasonCodes)
	Decode the status bytes of a SUBACK packet to a MQTTStatus_t.
static MQTTStatus_t	deserializeSubUnsubAck (const MQTTPacketInfo_t *incomingPacket, uint16_t *pPacketId, MQTTReasonCodeInfo_t *pReasonCodes, MQTTPropBuilder_t *pPropBuffer)
	Deserialize an MQTT SUBACK / UNSUBACK packet.
static MQTTStatus_t	deserializePublish (const MQTTPacketInfo_t *pIncomingPacket, uint16_t *pPacketId, MQTTPublishInfo_t *pPublishInfo, MQTTPropBuilder_t *pPropBuffer, uint16_t topicAliasMax)
	Deserialize a PUBLISH packet received from the server.
static MQTTStatus_t	deserializePingresp (const MQTTPacketInfo_t *pPingresp)
	Deserialize a PINGRESP packet.
static MQTTStatus_t	validateConnackParams (const MQTTPacketInfo_t *pIncomingPacket, bool *pSessionPresent)
	Validate the connack parameters.
static MQTTStatus_t	deserializeConnackProperties (MQTTConnectionProperties_t *pConnackProperties, uint32_t length, uint8_t *pIndex, MQTTPropBuilder_t *pPropBuffer)
	Validate the length and decode the connack properties.
static MQTTStatus_t	deserializeSubUnsubAckProperties (MQTTPropBuilder_t *pPropBuffer, uint8_t *pIndex, size_t *pSubackPropertyLength, uint32_t remainingLength)
	Deserialize properties in the SUBACK packet received from the server.
static MQTTStatus_t	deserializePubAcks (const MQTTPacketInfo_t *pAck, uint16_t *pPacketIdentifier, MQTTReasonCodeInfo_t *pReasonCode, bool requestProblem, MQTTPropBuilder_t *pPropBuffer)
	Deserialize an PUBACK, PUBREC, PUBREL, or PUBCOMP packet.
static MQTTStatus_t	decodePubAckProperties (MQTTPropBuilder_t *pPropBuffer, uint8_t *pIndex, uint32_t remainingLength)
	Validate the length and decode the publish ack properties.
static MQTTStatus_t	logAckResponse (MQTTSuccessFailReasonCode_t reasonCode, uint16_t packetIdentifier)
	Prints the appropriate message for the PUBREL, PUBACK response code if logs are enabled.
static MQTTStatus_t	deserializePublishProperties (MQTTPublishInfo_t *pPublishInfo, MQTTPropBuilder_t *pPropBuffer, uint8_t *pIndex, uint16_t topicAliasMax, uint32_t remainingLength)
	Deserialize properties in the PUBLISH packet received from the server.
static MQTTStatus_t	validateDisconnectResponse (MQTTSuccessFailReasonCode_t reasonCode, bool incoming)
	Prints and validates the appropriate message for the Disconnect response code if logs are enabled.
static MQTTStatus_t	validateReasonCodeForAck (uint8_t ackPacketType, MQTTSuccessFailReasonCode_t reasonCode)
	Validates the reason codes for the given ACK packet type.
static MQTTStatus_t	isValidConnackReasonCode (uint8_t reasonCode)
	Validate if a reason code is valid for CONNACK packets.
static MQTTStatus_t	validateIncomingDisconnectProperties (uint8_t *pIndex, uint32_t disconnectPropertyLength)
	Validate properties in the DISCONNECT packet received from the server.
static MQTTStatus_t	deserializeConnackProperty (uint8_t propertyId, MQTTConnectionProperties_t *pConnackProperties, uint32_t *pPropertyLength, uint8_t **ppVariableHeader, MQTTPropBuilder_t *pPropBuffer, ConnackSeenFlags_t *pSeen)
	Decode and validate a single CONNACK property from the incoming packet.
static void	setConnackPropBit (MQTTPropBuilder_t *pPropBuffer, uint8_t bitPos)
	Set a bit in pPropBuffer->fieldSet if pPropBuffer is not NULL.
static MQTTStatus_t	validateBoolProp (uint8_t value, const char *pPropName)
	Validate that a uint8 property value is 0 or 1 (boolean).
static MQTTStatus_t	decodeConnackBoolProp (uint8_t *pDest, uint32_t *pPropertyLength, bool *pSeen, uint8_t **ppIndex, const char *pPropName, MQTTPropBuilder_t *pPropBuffer, uint8_t bitPos)
	Decode a uint8 boolean CONNACK property, validate it, and record it.
MQTTStatus_t	MQTT_SerializePublishHeaderWithoutTopic (const MQTTPublishInfo_t *pPublishInfo, uint32_t remainingLength, uint8_t *pBuffer, size_t *headerSize)
	Serialize an MQTT PUBLISH packet header without the topic string in the given buffer. This function will add the topic string length to the provided buffer. This helps reduce an unnecessary copy of the topic string into the buffer.
MQTTStatus_t	updateContextWithConnectProps (const MQTTPropBuilder_t *pPropBuilder, MQTTConnectionProperties_t *pConnectProperties)
	Updates the MQTT context with connect properties from the property builder.
MQTTStatus_t	MQTT_GetConnectPacketSize (const MQTTConnectInfo_t *pConnectInfo, const MQTTPublishInfo_t *pWillInfo, const MQTTPropBuilder_t *pConnectProperties, const MQTTPropBuilder_t *pWillProperties, uint32_t *pRemainingLength, uint32_t *pPacketSize)
	Get the size and Remaining Length of an MQTT Version 5 CONNECT packet.
MQTTStatus_t	MQTT_SerializeConnect (const MQTTConnectInfo_t *pConnectInfo, const MQTTPublishInfo_t *pWillInfo, const MQTTPropBuilder_t *pConnectProperties, const MQTTPropBuilder_t *pWillProperties, uint32_t remainingLength, const MQTTFixedBuffer_t *pFixedBuffer)
	Serialize an MQTT CONNECT packet in the given fixed buffer pFixedBuffer.
MQTTStatus_t	MQTT_GetSubscribePacketSize (const MQTTSubscribeInfo_t *pSubscriptionList, size_t subscriptionCount, const MQTTPropBuilder_t *pSubscribeProperties, uint32_t *pRemainingLength, uint32_t *pPacketSize, uint32_t maxPacketSize)
	Get packet size and Remaining Length of an MQTT SUBSCRIBE packet.
MQTTStatus_t	MQTT_SerializeSubscribe (const MQTTSubscribeInfo_t *pSubscriptionList, size_t subscriptionCount, const MQTTPropBuilder_t *pSubscribeProperties, uint16_t packetId, uint32_t remainingLength, const MQTTFixedBuffer_t *pFixedBuffer)
	Serialize an MQTT SUBSCRIBE packet in the given buffer.
MQTTStatus_t	MQTT_GetUnsubscribePacketSize (const MQTTSubscribeInfo_t *pSubscriptionList, size_t subscriptionCount, const MQTTPropBuilder_t *pUnsubscribeProperties, uint32_t *pRemainingLength, uint32_t *pPacketSize, uint32_t maxPacketSize)
	Get packet size and Remaining Length of an MQTT UNSUBSCRIBE packet.
MQTTStatus_t	MQTT_ValidateUnsubscribeProperties (const MQTTPropBuilder_t *pPropertyBuilder)
	Validates the properties specified for an MQTT UNSUBSCRIBE packet.
MQTTStatus_t	MQTT_SerializeUnsubscribe (const MQTTSubscribeInfo_t *pSubscriptionList, size_t subscriptionCount, const MQTTPropBuilder_t *pUnsubscribeProperties, uint16_t packetId, uint32_t remainingLength, const MQTTFixedBuffer_t *pFixedBuffer)
	Serialize an MQTT UNSUBSCRIBE packet with properties in the given buffer.
MQTTStatus_t	MQTT_GetPublishPacketSize (const MQTTPublishInfo_t *pPublishInfo, const MQTTPropBuilder_t *pPublishProperties, uint32_t *pRemainingLength, uint32_t *pPacketSize, uint32_t maxPacketSize)
	Get the packet size and remaining length of an MQTT PUBLISH packet.
MQTTStatus_t	MQTT_SerializePublish (const MQTTPublishInfo_t *pPublishInfo, const MQTTPropBuilder_t *pPublishProperties, uint16_t packetId, uint32_t remainingLength, const MQTTFixedBuffer_t *pFixedBuffer)
	Serialize an MQTT PUBLISH packet in the given buffer.
MQTTStatus_t	MQTT_SerializePublishHeader (const MQTTPublishInfo_t *pPublishInfo, const MQTTPropBuilder_t *pPublishProperties, uint16_t packetId, uint32_t remainingLength, const MQTTFixedBuffer_t *pFixedBuffer, size_t *pHeaderSize)
	Serialize an MQTT PUBLISH packet header in the given buffer.
static MQTTStatus_t	serializeAckWithProperties (const MQTTFixedBuffer_t *pFixedBuffer, uint8_t packetType, uint16_t packetId, const MQTTPropBuilder_t *pAckProperties, const MQTTSuccessFailReasonCode_t *pReasonCode)
	Serialize a publish ACK packet with properties into pFixedBuffer. Called only when pReasonCode != NULL and pAckProperties != NULL.
static MQTTStatus_t	serializeAckBody (const MQTTFixedBuffer_t *pFixedBuffer, uint8_t packetType, uint16_t packetId, const MQTTPropBuilder_t *pAckProperties, const MQTTSuccessFailReasonCode_t *pReasonCode)
	Validate parameters and serialize a publish ACK packet body. Handles the three cases: no reason code, reason code only, reason code + properties.
MQTTStatus_t	MQTT_SerializeAck (const MQTTFixedBuffer_t *pFixedBuffer, uint8_t packetType, uint16_t packetId, const MQTTPropBuilder_t *pAckProperties, const MQTTSuccessFailReasonCode_t *pReasonCode)
	Serialize an MQTT PUBACK, PUBREC, PUBREL, or PUBCOMP into the given buffer.
MQTTStatus_t	MQTT_GetDisconnectPacketSize (const MQTTPropBuilder_t *pDisconnectProperties, uint32_t *pRemainingLength, uint32_t *pPacketSize, uint32_t maxPacketSize, const MQTTSuccessFailReasonCode_t *pReasonCode)
	Get the size of an MQTT DISCONNECT packet.
MQTTStatus_t	MQTT_SerializeDisconnect (const MQTTPropBuilder_t *pDisconnectProperties, const MQTTSuccessFailReasonCode_t *pReasonCode, uint32_t remainingLength, const MQTTFixedBuffer_t *pFixedBuffer)
	Serialize an MQTT DISCONNECT packet into the given buffer.
MQTTStatus_t	MQTT_GetPingreqPacketSize (uint32_t *pPacketSize)
	Get the size of an MQTT PINGREQ packet.
MQTTStatus_t	MQTT_SerializePingreq (const MQTTFixedBuffer_t *pFixedBuffer)
	Serialize an MQTT PINGREQ packet into the given buffer.
MQTTStatus_t	MQTT_DeserializePublish (const MQTTPacketInfo_t *pIncomingPacket, uint16_t *pPacketId, MQTTPublishInfo_t *pPublishInfo, MQTTPropBuilder_t *propBuffer, uint32_t maxPacketSize, uint16_t topicAliasMax)
	Deserialize an MQTT PUBLISH packet.
MQTTStatus_t	MQTT_DeserializeConnAck (const MQTTPacketInfo_t *pIncomingPacket, bool *pSessionPresent, MQTTPropBuilder_t *pPropBuffer, MQTTConnectionProperties_t *pConnectProperties)
	Deserialize an MQTT CONNACK.
MQTTStatus_t	MQTT_DeserializeAck (const MQTTPacketInfo_t *pIncomingPacket, uint16_t *pPacketId, MQTTReasonCodeInfo_t *pReasonCode, MQTTPropBuilder_t *pPropBuffer, const MQTTConnectionProperties_t *pConnectProperties)
	Deserialize an MQTT PUBACK, PUBREC, PUBREL, PUBCOMP, SUBACK, UNSUBACK, or PINGRESP.
MQTTStatus_t	MQTT_GetIncomingPacketTypeAndLength (TransportRecv_t readFunc, NetworkContext_t *pNetworkContext, MQTTPacketInfo_t *pIncomingPacket)
	Extract the MQTT packet type and length from incoming packet.
MQTTStatus_t	MQTT_UpdateDuplicatePublishFlag (uint8_t *pHeader, bool set)
	Update the duplicate publish flag within the given header of the publish packet.
MQTTStatus_t	MQTT_ProcessIncomingPacketTypeAndLength (const uint8_t *pBuffer, const size_t *pIndex, MQTTPacketInfo_t *pIncomingPacket)
	Extract the MQTT packet type and length from incoming packet.
MQTTStatus_t	MQTT_InitConnect (MQTTConnectionProperties_t *pConnectProperties)
	Initialize an MQTTConnectionProperties_t.
MQTTStatus_t	MQTTPropertyBuilder_Init (MQTTPropBuilder_t *pPropertyBuilder, uint8_t *buffer, size_t length)
	Initialize the property builder.
MQTTStatus_t	MQTT_ValidateWillProperties (const MQTTPropBuilder_t *pPropertyBuilder)
	Validates the properties specified for WILL Properties in the MQTT CONNECT packet.
static MQTTStatus_t	checkOnce (uint32_t *pBitMask, uint8_t bitPos, const char *pPropName)
	Check that a property has not been seen before, then decode it. Returns MQTTBadResponse if the property appears more than once.
static MQTTStatus_t	validateConnectProperty (uint8_t propertyId, uint32_t *pPropertyLength, uint8_t **ppIndex, uint32_t *pBitMask, bool *pIsRequestProblemInfoSet, uint32_t *pPacketMaxSizeValue)
	Decode and validate a single CONNECT property.
MQTTStatus_t	MQTT_ValidateConnectProperties (const MQTTPropBuilder_t *pPropertyBuilder, bool *isRequestProblemInfoSet, uint32_t *pPacketMaxSizeValue)
	Validate the properties in a CONNECT packet.
MQTTStatus_t	MQTT_ValidateSubscribeProperties (bool isSubscriptionIdAvailable, const MQTTPropBuilder_t *propBuilder)
	Validates the properties of a SUBSCRIBE packet.
MQTTStatus_t	MQTT_ValidatePublishProperties (uint16_t serverTopicAliasMax, const MQTTPropBuilder_t *propBuilder, uint16_t *topicAlias)
	Validates the properties of a PUBLISH packet.
MQTTStatus_t	MQTT_ValidatePublishParams (const MQTTPublishInfo_t *pPublishInfo, uint8_t retainAvailable, uint8_t maxQos, uint16_t topicAlias, uint32_t maxPacketSize)
	Validate the publish parameters present in the given publish structure pPublishInfo.
MQTTStatus_t	MQTT_ValidatePublishAckProperties (const MQTTPropBuilder_t *pPropertyBuilder)
	Validates the properties specified for an MQTT PUBLISH ACK packet.
MQTTStatus_t	MQTT_GetAckPacketSize (uint32_t *pRemainingLength, uint32_t *pPacketSize, uint32_t maxPacketSize, size_t ackPropertyLength)
	Get the size of an outgoing PUBLISH ACK packet.
MQTTStatus_t	MQTT_ValidateDisconnectProperties (uint32_t connectSessionExpiry, const MQTTPropBuilder_t *pPropertyBuilder)
	Validates the properties specified for an MQTT DISCONNECT packet.
MQTTStatus_t	MQTT_DeserializeDisconnect (const MQTTPacketInfo_t *pPacket, uint32_t maxPacketSize, MQTTReasonCodeInfo_t *pDisconnectInfo, MQTTPropBuilder_t *pPropBuffer)
	Deserialize an MQTT Disconnect packet.

Detailed Description

Implements the user-facing functions in core_mqtt_serializer.h.

Function Documentation

serializePublishCommon()

static void serializePublishCommon ( const MQTTPublishInfo_t *  pPublishInfo, const MQTTPropBuilder_t *  pPublishProperties, uint32_t  remainingLength, uint16_t  packetIdentifier, const MQTTFixedBuffer_t *  pFixedBuffer, bool  serializePayload  )

static

Serializes MQTT PUBLISH packet into the buffer provided.

This function serializes MQTT PUBLISH packet into MQTTFixedBuffer_t.pBuffer. Copy of the payload into the buffer is done as part of the serialization only if serializePayload is true.

Parameters

[in]	pPublishInfo	Publish information containing topic, QoS, payload and other PUBLISH packet fields.
[in]	pPublishProperties	MQTT v5.0 properties for the PUBLISH packet. Can be NULL if no properties are needed.
[in]	remainingLength	Remaining length of the PUBLISH packet.
[in]	packetIdentifier	Packet identifier of PUBLISH packet.
[in,out]	pFixedBuffer	Buffer to which PUBLISH packet will be serialized.
[in]	serializePayload	Copy payload to the serialized buffer only if true. Only PUBLISH header will be serialized if false.

calculatePublishPacketSize()

static MQTTStatus_t calculatePublishPacketSize ( const MQTTPublishInfo_t *  pPublishInfo, uint32_t *  pRemainingLength, uint32_t *  pPacketSize, uint32_t  maxPacketSize, uint32_t  publishPropertyLength  )

static

Calculates the packet size and remaining length of an MQTT PUBLISH packet.

Parameters

[in]	pPublishInfo	MQTT PUBLISH packet parameters.
[out]	pRemainingLength	The Remaining Length of the MQTT PUBLISH packet.
[out]	pPacketSize	The total size of the MQTT PUBLISH packet.
[in]	maxPacketSize	Max packet size allowed by the server.
[in]	publishPropertyLength	Length of the optional properties in MQTT_PUBLISH

Returns

MQTTBadParameter if the packet would exceed the size allowed by the MQTT spec; MQTTSuccess otherwise.

calculateSubscriptionPacketSize()

static MQTTStatus_t calculateSubscriptionPacketSize ( const MQTTSubscribeInfo_t *  pSubscriptionList, size_t  subscriptionCount, uint32_t *  pRemainingLength, uint32_t *  pPacketSize, uint32_t  subscribePropLen, uint32_t  maxPacketSize, MQTTSubscriptionType_t  subscriptionType  )

static

Calculates the packet size and remaining length of an MQTT SUBSCRIBE or UNSUBSCRIBE packet.

Parameters

[in]	pSubscriptionList	List of MQTT subscription info.
[in]	subscriptionCount	The number of elements in pSubscriptionList.
[out]	pRemainingLength	The Remaining Length of the MQTT SUBSCRIBE or UNSUBSCRIBE packet.
[out]	pPacketSize	The total size of the MQTT SUBSCRIBE or MQTT UNSUBSCRIBE packet.
[in]	subscribePropLen	Length of the optional properties in MQTT_SUBSCRIBE or MQTT_UNSUBSCRIBE
[in]	maxPacketSize	Maximum Packet Size allowed by the broker
[in]	subscriptionType	MQTT_TYPE_SUBSCRIBE or MQTT_TYPE_UNSUBSCRIBE.

Returns

MQTTBadParameter if the packet would exceed the size allowed by the MQTT spec or a subscription is empty; MQTTSuccess otherwise.

validateSubscriptionSerializeParams()

static MQTTStatus_t validateSubscriptionSerializeParams ( const MQTTSubscribeInfo_t *  pSubscriptionList, size_t  subscriptionCount, uint16_t  packetId, uint32_t  remainingLength, const MQTTFixedBuffer_t *  pFixedBuffer  )

static

Validates parameters of MQTT_SerializeSubscribe or MQTT_SerializeUnsubscribe.

Parameters

[in]	pSubscriptionList	List of MQTT subscription info.
[in]	subscriptionCount	The number of elements in pSubscriptionList.
[in]	packetId	Packet identifier.
[in]	remainingLength	Remaining length of the packet.
[in]	pFixedBuffer	Buffer for packet serialization.

Returns

MQTTNoMemory if pBuffer is too small to hold the MQTT packet; MQTTBadParameter if invalid parameters are passed; MQTTSuccess otherwise.

serializeConnectPacket()

static void serializeConnectPacket ( const MQTTConnectInfo_t *  pConnectInfo, const MQTTPublishInfo_t *  pWillInfo, const MQTTPropBuilder_t *  pConnectProperties, const MQTTPropBuilder_t *  pWillProperties, uint32_t  remainingLength, const MQTTFixedBuffer_t *  pFixedBuffer  )

static

Serialize an MQTT CONNECT packet in the given buffer.

Parameters

[in]	pConnectInfo	MQTT CONNECT packet parameters.
[in]	pWillInfo	Last Will and Testament. Pass NULL if not used.
[in]	pConnectProperties	MQTT CONNECT properties.
[in]	pWillProperties	MQTT Will properties.
[in]	remainingLength	Remaining Length of MQTT CONNECT packet.
[out]	pFixedBuffer	Buffer for packet serialization.

logConnackResponse()

static void logConnackResponse ( uint8_t  responseCode )

static

Prints the appropriate message for the CONNACK response code if logs are enabled.

Parameters

[in]

responseCode

MQTT standard CONNACK response code.

remainingLengthEncodedSize()

static uint32_t remainingLengthEncodedSize ( uint32_t  length )

static

Retrieve the size of the remaining length if it were to be encoded.

Parameters

[in]

length

The remaining length to be encoded.

Returns

The size of the remaining length if it were to be encoded.

getRemainingLength()

static uint32_t getRemainingLength ( TransportRecv_t  recvFunc, NetworkContext_t *  pNetworkContext  )

static

Retrieves and decodes the Remaining Length from the network interface by reading a single byte at a time.

Parameters

[in]	recvFunc	Network interface receive function.
[in]	pNetworkContext	Network interface context to the receive function.

Returns

The Remaining Length of the incoming packet.

processRemainingLength()

static MQTTStatus_t processRemainingLength ( const uint8_t *  pBuffer, const size_t *  pIndex, MQTTPacketInfo_t *  pIncomingPacket  )

static

Retrieves, decodes and stores the Remaining Length from the network interface by reading a single byte at a time.

Parameters

[in]	pBuffer	The buffer holding the raw data to be processed
[in]	pIndex	Pointer to the index within the buffer to marking the end of raw data available.
[in]	pIncomingPacket	Structure used to hold the fields of the incoming packet.

Returns

MQTTNeedMoreBytes is returned to show that the incoming packet is not yet fully received and decoded. Otherwise, MQTTSuccess shows that processing of the packet was successful.

incomingPacketValid()

static bool incomingPacketValid ( uint8_t  packetType )

static

Check if an incoming packet type is valid.

Parameters

[in]

packetType

The packet type to check.

Returns

true if the packet type is valid; false otherwise.

checkPublishRemainingLength()

static MQTTStatus_t checkPublishRemainingLength ( uint32_t  remainingLength, MQTTQoS_t  qos, uint32_t  qos0Minimum  )

static

Check the remaining length of an incoming PUBLISH packet against some value for QoS 0, or for QoS 1 and 2.

The remaining length for a QoS 1 and 2 packet will always be two greater than for a QoS 0.

Parameters

[in]	remainingLength	Remaining length of the PUBLISH packet.
[in]	qos	The QoS of the PUBLISH.
[in]	qos0Minimum	Minimum possible remaining length for a QoS 0 PUBLISH.

Returns

MQTTSuccess or MQTTBadResponse.

processPublishFlags()

static MQTTStatus_t processPublishFlags ( uint8_t  publishFlags, MQTTPublishInfo_t *  pPublishInfo  )

static

Process the flags of an incoming PUBLISH packet.

Parameters

[in]	publishFlags	Flags of an incoming PUBLISH.
[in,out]	pPublishInfo	Pointer to MQTTPublishInfo_t struct where output will be written.

Returns

MQTTSuccess or MQTTBadResponse.

deserializeConnack()

static MQTTStatus_t deserializeConnack ( MQTTConnectionProperties_t *  pConnackProperties, const MQTTPacketInfo_t *  pIncomingPacket, bool *  pSessionPresent, MQTTPropBuilder_t *  pPropBuffer  )

static

Deserialize an MQTT CONNACK packet.

Parameters

[out]	pConnackProperties	To store the deserialized connack properties.
[in]	pIncomingPacket	MQTTPacketInfo_t containing the buffer.
[out]	pSessionPresent	Whether a previous session was present.
[out]	pPropBuffer	MQTTPropBuilder_t to store the deserialized properties.

Returns

MQTTBadParameter, MQTTBadResponse, MQTTSuccess, MQTTServerRefused

readSubackStatus()

static MQTTStatus_t readSubackStatus ( size_t  statusCount, const uint8_t *  pStatusStart, MQTTReasonCodeInfo_t *  pReasonCodes  )

static

Decode the status bytes of a SUBACK packet to a MQTTStatus_t.

Parameters

[in]	statusCount	Number of status bytes in the SUBACK.
[in]	pStatusStart	The first status byte in the SUBACK.
[out]	pReasonCodes	The MQTTReasonCodeInfo_t to store reason codes for each topic filter.

Returns

MQTTSuccess, MQTTServerRefused, or MQTTBadResponse.

deserializeSubUnsubAck()

static MQTTStatus_t deserializeSubUnsubAck ( const MQTTPacketInfo_t *  incomingPacket, uint16_t *  pPacketId, MQTTReasonCodeInfo_t *  pReasonCodes, MQTTPropBuilder_t *  pPropBuffer  )

static

Deserialize an MQTT SUBACK / UNSUBACK packet.

Parameters

[in]	incomingPacket	MQTTPacketInfo_t containing the buffer.
[out]	pPacketId	The packet ID obtained from the buffer.
[out]	pReasonCodes	Struct to store reason code(s) from the acknowledgment packet. Contains the success/failure status of the corresponding request.
[out]	pPropBuffer	MQTTPropBuilder_t to store the deserialized properties.

Returns

MQTTBadParameter, MQTTBadResponse, MQTTSuccess, MQTTServerRefused

deserializePublish()

static MQTTStatus_t deserializePublish ( const MQTTPacketInfo_t *  pIncomingPacket, uint16_t *  pPacketId, MQTTPublishInfo_t *  pPublishInfo, MQTTPropBuilder_t *  pPropBuffer, uint16_t  topicAliasMax  )

static

Deserialize a PUBLISH packet received from the server.

Converts the packet from a stream of bytes to an MQTTPublishInfo_t and extracts the packet identifier. Also prints out debug log messages about the packet.

Parameters

[in]	pIncomingPacket	Pointer to an MQTT packet struct representing a PUBLISH.
[out]	pPacketId	Packet identifier of the PUBLISH.
[out]	pPublishInfo	Pointer to MQTTPublishInfo_t where output is written.
[out]	pPropBuffer	Pointer to the property buffer.
[in]	topicAliasMax	Maximum allowed Topic Alias.

Returns

MQTTSuccess if PUBLISH is valid; MQTTBadResponse if the PUBLISH packet doesn't follow MQTT spec.

deserializePingresp()

static MQTTStatus_t deserializePingresp ( const MQTTPacketInfo_t *  pPingresp )

static

Deserialize a PINGRESP packet.

Converts the packet from a stream of bytes to an MQTTStatus_t.

Parameters

[in]

pPingresp

Pointer to an MQTT packet struct representing a PINGRESP.

Returns

MQTTSuccess if PINGRESP is valid; MQTTBadResponse if the PINGRESP packet doesn't follow MQTT spec.

validateConnackParams()

static MQTTStatus_t validateConnackParams ( const MQTTPacketInfo_t *  pIncomingPacket, bool *  pSessionPresent  )

static

Validate the connack parameters.

Converts the packet from a stream of bytes to an MQTTStatus_t and extracts the variable header without connack properties.

Parameters

[in]	pIncomingPacket	Pointer to an MQTT packet struct representing a incoming packet.
[out]	pSessionPresent	Whether a session is present or not.

Returns

MQTTSuccess if connack without connack properties is valid; MQTTServerRefused if the server refused the connection; MQTTBadResponse if the Connack packet doesn't follow MQTT spec.

deserializeConnackProperties()

static MQTTStatus_t deserializeConnackProperties ( MQTTConnectionProperties_t *  pConnackProperties, uint32_t  length, uint8_t *  pIndex, MQTTPropBuilder_t *  pPropBuffer  )

static

Validate the length and decode the connack properties.

Parameters

[out]	pConnackProperties	To store the decoded property.
[in]	length	Length of the properties.
[in]	pIndex	Pointer to the start of the properties.
[out]	pPropBuffer	Pointer to the property buffer.

Returns

MQTTSuccess, MQTTBadResponse

deserializeSubUnsubAckProperties()

static MQTTStatus_t deserializeSubUnsubAckProperties ( MQTTPropBuilder_t *  pPropBuffer, uint8_t *  pIndex, size_t *  pSubackPropertyLength, uint32_t  remainingLength  )

static

Deserialize properties in the SUBACK packet received from the server.

Converts the packet from a stream of bytes to an MQTTStatus_t and extracts properties.

Parameters

[out]	pPropBuffer	Pointer to the property buffer.
[in]	pIndex	Pointer to the start of the properties.
[out]	pSubackPropertyLength	Pointer to the length of suback properties
[in]	remainingLength	Remaining length of the incoming packet.

Returns

MQTTSuccess if SUBACK is valid; MQTTBadResponse if SUBACK is invalid.

deserializePubAcks()

static MQTTStatus_t deserializePubAcks ( const MQTTPacketInfo_t *  pAck, uint16_t *  pPacketIdentifier, MQTTReasonCodeInfo_t *  pReasonCode, bool  requestProblem, MQTTPropBuilder_t *  pPropBuffer  )

static

Deserialize an PUBACK, PUBREC, PUBREL, or PUBCOMP packet.

Converts the packet from a stream of bytes to an MQTTStatus_t and extracts the packet identifier, reason code, properties.

Parameters

[in]	pAck	Pointer to the MQTT packet structure representing the packet.
[out]	pPacketIdentifier	Packet ID of the ack type packet.
[out]	pReasonCode	Structure to store reason code of the ack type packet.
[in]	requestProblem	To validate the packet.
[out]	pPropBuffer	Pointer to the property buffer.

Returns

MQTTSuccess, MQTTBadResponse, MQTTBadParameter.

decodePubAckProperties()

static MQTTStatus_t decodePubAckProperties ( MQTTPropBuilder_t *  pPropBuffer, uint8_t *  pIndex, uint32_t  remainingLength  )

static

Validate the length and decode the publish ack properties.

Parameters

[out]	pPropBuffer	To store the decoded property.
[in]	pIndex	Pointer to the current index of the buffer.
[in]	remainingLength	Remaining length of properties in the incoming packet.

Returns

MQTTSuccess, MQTTBadResponse.

logAckResponse()

static MQTTStatus_t logAckResponse ( MQTTSuccessFailReasonCode_t  reasonCode, uint16_t  packetIdentifier  )

static

Prints the appropriate message for the PUBREL, PUBACK response code if logs are enabled.

Parameters

[in]	reasonCode	MQTT Verion 5 standard PUBREL, PUBACK response code.
[in]	packetIdentifier	Packet id of the ack packet.

Returns

MQTTSuccess, MQTTServerRefused and MQTTBadResponse.

deserializePublishProperties()

static MQTTStatus_t deserializePublishProperties ( MQTTPublishInfo_t *  pPublishInfo, MQTTPropBuilder_t *  pPropBuffer, uint8_t *  pIndex, uint16_t  topicAliasMax, uint32_t  remainingLength  )

static

Deserialize properties in the PUBLISH packet received from the server.

Converts the packet from a stream of bytes to an MQTTPublishInfo_t and extracts properties.

Parameters

[out]	pPublishInfo	Pointer to MQTTPublishInfo_t where output is written.
[out]	pPropBuffer	Pointer to the property buffer.
[in]	pIndex	Pointer to the start of the properties.
[in]	topicAliasMax	Maximum allowed Topic Alias.
[in]	remainingLength	Remaining length of the incoming packet.

Returns

MQTTSuccess if PUBLISH is valid; MQTTBadResponse if the PUBLISH packet doesn't follow MQTT spec.

validateDisconnectResponse()

static MQTTStatus_t validateDisconnectResponse ( MQTTSuccessFailReasonCode_t  reasonCode, bool  incoming  )

static

Prints and validates the appropriate message for the Disconnect response code if logs are enabled.

Parameters

[in]	reasonCode	MQTT Verion 5 standard DISCONNECT response code.
[in]	incoming	To differentiate between outgoing and incoming disconnect.

Returns

MQTTSuccess, MQTTBadParameter and MQTTBadResponse.

validateReasonCodeForAck()

static MQTTStatus_t validateReasonCodeForAck ( uint8_t  ackPacketType, MQTTSuccessFailReasonCode_t  reasonCode  )

static

Validates the reason codes for the given ACK packet type.

Parameters

[in]	ackPacketType	ACK packet type for which the reason code is being added.
[in]	reasonCode	The reason code being added to the ACK packet type.

Returns

MQTTSuccess or MQTTBadParameter.

isValidConnackReasonCode()

static MQTTStatus_t isValidConnackReasonCode ( uint8_t  reasonCode )

inlinestatic

Validate if a reason code is valid for CONNACK packets.

This function checks if the provided reason code is a valid CONNACK reason code according to the MQTT v5 specification.

Parameters

[in]

reasonCode

The reason code to validate.

Returns

MQTTSuccess if the reason code is valid for CONNACK; MQTTServerRefused if the reason code indicates server refusal; MQTTBadResponse if the reason code is invalid.

validateIncomingDisconnectProperties()

static MQTTStatus_t validateIncomingDisconnectProperties ( uint8_t *  pIndex, uint32_t  disconnectPropertyLength  )

static

Validate properties in the DISCONNECT packet received from the server.

Note

Incoming properties are different than the ones the client can send.

Parameters

[in]	pIndex	Pointer to the start of the properties.
[in]	disconnectPropertyLength	Length of the properties in the DISCONNECT packet.

Returns

MQTTSuccess if DISCONNECT is valid; MQTTBadResponse if the DISCONNECT packet is invalid.

deserializeConnackProperty()

static MQTTStatus_t deserializeConnackProperty ( uint8_t  propertyId, MQTTConnectionProperties_t *  pConnackProperties, uint32_t *  pPropertyLength, uint8_t **  ppVariableHeader, MQTTPropBuilder_t *  pPropBuffer, ConnackSeenFlags_t *  pSeen  )

static

Decode and validate a single CONNACK property from the incoming packet.

Reads one property from the variable header, validates its value, stores it in the appropriate field of pConnackProperties, and sets the corresponding bit in the property buffer's fieldSet if pPropBuffer is not NULL.

Parameters

[in]	propertyId	The MQTT property identifier byte.
[in,out]	pConnackProperties	Connection properties structure to populate.
[in,out]	pPropertyLength	Remaining bytes in the property section; decremented as each property value is consumed.
[in,out]	ppVariableHeader	Pointer to the current read position in the packet buffer; advanced past the consumed property value.
[in,out]	pPropBuffer	Optional property builder to record which properties were received. May be NULL.
[in,out]	pSeen	Duplicate-detection flags for each CONNACK property.

Returns

MQTTSuccess if the property was decoded and validated successfully.

MQTTBadResponse if the property value is invalid (e.g., boolean out of range, zero where prohibited, response info sent without being requested) or if an unknown property ID is encountered.

setConnackPropBit()

static void setConnackPropBit ( MQTTPropBuilder_t *  pPropBuffer, uint8_t  bitPos  )

static

Set a bit in pPropBuffer->fieldSet if pPropBuffer is not NULL.

Parameters

[in,out]	pPropBuffer	Property builder whose fieldSet will be updated. If NULL, this function does nothing.
[in]	bitPos	Bit position to set in fieldSet.

validateBoolProp()

static MQTTStatus_t validateBoolProp ( uint8_t  value, const char *  pPropName  )

static

Validate that a uint8 property value is 0 or 1 (boolean).

Parameters

[in]	value	The decoded uint8 property value to validate.
[in]	pPropName	Human-readable property name used in the error log message.

Returns

MQTTSuccess if value is 0 or 1.

MQTTBadResponse if value is greater than 1.

decodeConnackBoolProp()

static MQTTStatus_t decodeConnackBoolProp ( uint8_t *  pDest, uint32_t *  pPropertyLength, bool *  pSeen, uint8_t **  ppIndex, const char *  pPropName, MQTTPropBuilder_t *  pPropBuffer, uint8_t  bitPos  )

static

Decode a uint8 boolean CONNACK property, validate it, and record it.

Calls decodeUint8t to read the value, validateBoolProp to check it is 0 or 1, and setConnackPropBit to mark the property as received in the property buffer.

Parameters

[out]	pDest	Destination to store the decoded uint8 value.
[in,out]	pPropertyLength	Remaining bytes in the property section; decremented by the size of the decoded value.
[in,out]	pSeen	Duplicate-detection flag; set to true after first decode.
[in,out]	ppIndex	Current read position in the packet buffer; advanced past the decoded value.
[in]	pPropName	Human-readable property name used in error log messages.
[in,out]	pPropBuffer	Optional property builder to record the property bit. May be NULL.
[in]	bitPos	Bit position to set in pPropBuffer->fieldSet on success.

Returns

MQTTSuccess if the property was decoded and validated successfully.

MQTTBadResponse if the value is not 0 or 1, or if decoding fails.

MQTT_SerializePublishHeaderWithoutTopic()

MQTTStatus_t MQTT_SerializePublishHeaderWithoutTopic	(	const MQTTPublishInfo_t *	pPublishInfo,
		uint32_t	remainingLength,
		uint8_t *	pBuffer,
		size_t *	headerSize
	)

Serialize an MQTT PUBLISH packet header without the topic string in the given buffer. This function will add the topic string length to the provided buffer. This helps reduce an unnecessary copy of the topic string into the buffer.

Parameters

[in]	pPublishInfo	MQTT PUBLISH packet parameters.
[in]	remainingLength	Remaining Length provided by MQTT_GetPublishPacketSize.
[out]	pBuffer	Buffer for packet serialization.
[out]	headerSize	Size of the serialized MQTT PUBLISH header.

Returns

MQTTSuccess if the serialization is successful. Otherwise, MQTTBadParameter.

updateContextWithConnectProps()

MQTTStatus_t updateContextWithConnectProps	(	const MQTTPropBuilder_t *	pPropBuilder,
		MQTTConnectionProperties_t *	pConnectProperties
	)

Updates the MQTT context with connect properties from the property builder.

This function processes the property builder and updates the connect properties in the MQTT context. It handles the conversion and validation of properties from the property builder to the connect properties structure.

Parameters

[in]	pPropBuilder	Pointer to the property builder containing MQTT properties. Must not be NULL.
[out]	pConnectProperties	Pointer to the connection properties structure to be updated. Must not be NULL.

Returns

Returns one of the following:

• MQTTSuccess if properties were successfully updated
• MQTTBadParameter, MQTTBadResponse if invalid parameters are passed

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTPropBuilder_t propBuilder = { 0 };
MQTTConnectionProperties_t connectionProperties = { 0 };
 
// Initialize property builder with desired properties
// ...
 
// Update connect properties
status = updateContextWithConnectProps( &propBuilder, &connectionProperties );
 
if(status == MQTTSuccess)
{
    // Properties successfully updated in the context
}

This value shall get overwritten if the server sends a sessionExpiry in the CONNACK.

MQTT_GetConnectPacketSize()

MQTTStatus_t MQTT_GetConnectPacketSize	(	const MQTTConnectInfo_t *	pConnectInfo,
		const MQTTPublishInfo_t *	pWillInfo,
		const MQTTPropBuilder_t *	pConnectProperties,
		const MQTTPropBuilder_t *	pWillProperties,
		uint32_t *	pRemainingLength,
		uint32_t *	pPacketSize
	)

Get the size and Remaining Length of an MQTT Version 5 CONNECT packet.

This function must be called before MQTT_SerializeConnect in order to get the size of the MQTT CONNECT packet that is generated from MQTTConnectInfo_t, MQTTPublishInfo_t and optional MQTTPropBuilder_t. The size of the MQTTFixedBuffer_t supplied to MQTT_SerializeConnect must be at least pPacketSize. The provided pConnectInfo and pWillInfo are valid for serialization with MQTT_SerializeConnect only if this function returns MQTTSuccess. The remaining length returned in pRemainingLength and the packet size returned in pPacketSize are valid only if this function returns MQTTSuccess.

Parameters

[in]	pConnectInfo	MQTT CONNECT packet parameters.
[in]	pWillInfo	Last Will and Testament. Pass NULL if not used.
[in]	pConnectProperties	MQTT CONNECT properties builder. Pass NULL if not used.
[in]	pWillProperties	MQTT Will properties builder. Pass NULL if not used.
[out]	pRemainingLength	The Remaining Length of the MQTT CONNECT packet.
[out]	pPacketSize	The total size of the MQTT CONNECT packet.

Returns

MQTTBadParameter if the packet would exceed the size allowed by the MQTT spec; MQTTSuccess otherwise.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTConnectInfo_t connectInfo = { 0 };
MQTTPublishInfo_t willInfo = { 0 };
MQTTPropBuilder_t connectionProperties = { 0 };
MQTTPropBuilder_t willProperties = { 0 };
size_t remainingLength = 0, packetSize = 0;
 
// Initialize the connection info, the details are out of scope for this example.
initializeConnectInfo( &connectInfo );
 
// Initialize the optional will info, the details are out of scope for this example.
initializeWillInfo( &willInfo );
 
// Initialize connect properties and will properties, the details are out of scope for this example.
initializeConnectProperties( &connectionProperties );
initializeWillProperties( &willProperties );
 
// Get the size requirement for the connect packet.
status = MQTT_GetConnectPacketSize(
     &connectInfo,
     &willInfo,
     &connectionProperties,
     &willProperties,
     &remainingLength,
     &packetSize
);
 
if( status == MQTTSuccess )
{
     // The application should allocate or use a static #MQTTFixedBuffer_t
     // of size >= packetSize to serialize the connect request.
}

MQTT_SerializeConnect()

MQTTStatus_t MQTT_SerializeConnect	(	const MQTTConnectInfo_t *	pConnectInfo,
		const MQTTPublishInfo_t *	pWillInfo,
		const MQTTPropBuilder_t *	pConnectProperties,
		const MQTTPropBuilder_t *	pWillProperties,
		uint32_t	remainingLength,
		const MQTTFixedBuffer_t *	pFixedBuffer
	)

Serialize an MQTT CONNECT packet in the given fixed buffer pFixedBuffer.

MQTT_GetConnectPacketSize should be called with pConnectInfo, pWillInfo, pConnectProperties, and pWillProperties before invoking this function to get the size of the required MQTTFixedBuffer_t and remainingLength. The remainingLength must be the same as returned by MQTT_GetConnectPacketSize. The MQTTFixedBuffer_t must be at least as large as the size returned by MQTT_GetConnectPacketSize.

Parameters

[in]	pConnectInfo	MQTT CONNECT packet parameters.
[in]	pWillInfo	Last Will and Testament. Pass NULL if not used.
[in]	pConnectProperties	MQTT CONNECT properties builder. Pass NULL if not used.
[in]	pWillProperties	MQTT Will properties builder. Pass NULL if not used.
[in]	remainingLength	Remaining Length provided by MQTT_GetConnectPacketSize.
[out]	pFixedBuffer	Buffer for packet serialization.

Returns

MQTTNoMemory if pFixedBuffer is too small to hold the MQTT packet; MQTTBadParameter if invalid parameters are passed; MQTTSuccess otherwise.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTConnectInfo_t connectInfo = { 0 };
MQTTPublishInfo_t willInfo = { 0 };
MQTTPropBuilder_t connectionProperties = { 0 };
MQTTPropBuilder_t willProperties = { 0 };
MQTTFixedBuffer_t fixedBuffer;
uint8_t buffer[ BUFFER_SIZE ];
size_t remainingLength = 0, packetSize = 0;
 
fixedBuffer.pBuffer = buffer;
fixedBuffer.size = BUFFER_SIZE;
 
// Assume connectInfo, willInfo, and properties are initialized.
// Get the size requirement for the connect packet.
status = MQTT_GetConnectPacketSize(
     &connectInfo, &willInfo, &connectionProperties, &willProperties,
     &remainingLength, &packetSize
);
assert( status == MQTTSuccess );
assert( packetSize <= BUFFER_SIZE );
 
// Serialize the connect packet into the fixed buffer.
status = MQTT_SerializeConnect(
     &connectInfo,
     &willInfo,
     &connectionProperties,
     &willProperties,
     remainingLength,
     &fixedBuffer
);
 
if( status == MQTTSuccess )
{
     // The connect packet can now be sent to the broker.
}

MQTT_GetSubscribePacketSize()

MQTTStatus_t MQTT_GetSubscribePacketSize	(	const MQTTSubscribeInfo_t *	pSubscriptionList,
		size_t	subscriptionCount,
		const MQTTPropBuilder_t *	pSubscribeProperties,
		uint32_t *	pRemainingLength,
		uint32_t *	pPacketSize,
		uint32_t	maxPacketSize
	)

Get packet size and Remaining Length of an MQTT SUBSCRIBE packet.

This function must be called before MQTT_SerializeSubscribe in order to get the size of the MQTT SUBSCRIBE packet that is generated from the list of MQTTSubscribeInfo_t and MQTTPropBuilder_t (optional subscribe properties). The size of the MQTTFixedBuffer_t supplied to MQTT_SerializeSubscribe must be at least pPacketSize. The provided pSubscriptionList is valid for serialization with MQTT_SerializeSubscribe only if this function returns MQTTSuccess. The remaining length returned in pRemainingLength and the packet size returned in pPacketSize are valid only if this function returns MQTTSuccess.

Parameters

[in]	pSubscriptionList	List of MQTT subscription info.
[in]	subscriptionCount	The number of elements in pSubscriptionList.
[in]	pSubscribeProperties	MQTT SUBSCRIBE properties builder. Pass NULL if not used.
[out]	pRemainingLength	The Remaining Length of the MQTT SUBSCRIBE packet.
[out]	pPacketSize	The total size of the MQTT SUBSCRIBE packet.
[in]	maxPacketSize	Maximum packet size.

Returns

MQTTBadParameter if the packet would exceed the size allowed by the MQTT spec; MQTTSuccess otherwise.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTSubscribeInfo_t subscriptionList[ NUMBER_OF_SUBSCRIPTIONS ] = { 0 };
MQTTPropBuilder_t subscribeProperties = { 0 };
size_t remainingLength = 0, packetSize = 0;
// This is assumed to be a list of filters we want to subscribe to.
const char * filters[ NUMBER_OF_SUBSCRIPTIONS ];
 
// Set each subscription.
for( int i = 0; i < NUMBER_OF_SUBSCRIPTIONS; i++ )
{
     subscriptionList[ i ].qos = MQTTQoS0;
     // Each subscription needs a topic filter.
     subscriptionList[ i ].pTopicFilter = filters[ i ];
     subscriptionList[ i ].topicFilterLength = strlen( filters[ i ] );
     subscriptionList[ i ].noLocalOption = false;
     subscriptionList[ i ].retainAsPublishedOption = false;
     subscriptionList[ i ].retainHandlingOption = retainSendOnSub;
}
 
// Initialize subscribe properties (if needed)
initializeSubscribeProperties( &subscribeProperties );
 
// Get the size requirement for the subscribe packet.
status = MQTT_GetSubscribePacketSize(
     &subscriptionList[ 0 ],
     NUMBER_OF_SUBSCRIPTIONS,
     &subscribeProperties,
     &remainingLength,
     &packetSize,
     maxPacketSize
);
 
if( status == MQTTSuccess )
{
     // The application should allocate or use a static #MQTTFixedBuffer_t
     // of size >= packetSize to serialize the subscribe request.
}

MQTT_SerializeSubscribe()

MQTTStatus_t MQTT_SerializeSubscribe	(	const MQTTSubscribeInfo_t *	pSubscriptionList,
		size_t	subscriptionCount,
		const MQTTPropBuilder_t *	pSubscribeProperties,
		uint16_t	packetId,
		uint32_t	remainingLength,
		const MQTTFixedBuffer_t *	pFixedBuffer
	)

Serialize an MQTT SUBSCRIBE packet in the given buffer.

MQTT_GetSubscribePacketSize should be called with pSubscriptionList before invoking this function to get the size of the required MQTTFixedBuffer_t and remainingLength. The remainingLength must be the same as returned by MQTT_GetSubscribePacketSize. The MQTTFixedBuffer_t must be at least as large as the size returned by MQTT_GetSubscribePacketSize.

Parameters

[in]	pSubscriptionList	List of MQTT subscription info.
[in]	subscriptionCount	The number of elements in pSubscriptionList.
[in]	pSubscribeProperties	MQTT v5.0 properties for the SUBSCRIBE packet. Can be NULL if no properties are needed.
[in]	packetId	packet ID generated by MQTT_GetPacketId.
[in]	remainingLength	Remaining Length provided by MQTT_GetSubscribePacketSize.
[out]	pFixedBuffer	Buffer for packet serialization.

Returns

MQTTNoMemory if pFixedBuffer is too small to hold the MQTT packet; MQTTBadParameter if invalid parameters are passed; MQTTSuccess otherwise.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTSubscribeInfo_t subscriptionList[ NUMBER_OF_SUBSCRIPTIONS ] = { 0 };
MQTTPropBuilder_t subscribeProperties = { 0 };
MQTTFixedBuffer_t fixedBuffer;
uint8_t buffer[ BUFFER_SIZE ];
size_t remainingLength = 0, packetSize = 0;
uint16_t packetId;
 
fixedBuffer.pBuffer = buffer;
fixedBuffer.size = BUFFER_SIZE;
 
// Function to return a valid, unused packet identifier. The details are out of
// scope for this example.
packetId = getNewPacketId();
 
// Assume subscriptionList and subscribeProperties have been initialized.
Get the subscribe packet size.
status = MQTT_GetSubscribePacketSize(
     &subscriptionList[ 0 ], NUMBER_OF_SUBSCRIPTIONS, &subscribeProperties,
     &remainingLength, &packetSize
);
assert( status == MQTTSuccess );
assert( packetSize <= BUFFER_SIZE );
 
// Serialize the subscribe packet into the fixed buffer.
status = MQTT_SerializeSubscribe(
     &subscriptionList[ 0 ],
     NUMBER_OF_SUBSCRIPTIONS,
     &subscribeProperties,
     packetId,
     remainingLength,
     &fixedBuffer
);
 
if( status == MQTTSuccess )
{
     // The subscribe packet can now be sent to the broker.
}

MQTT_GetUnsubscribePacketSize()

MQTTStatus_t MQTT_GetUnsubscribePacketSize	(	const MQTTSubscribeInfo_t *	pSubscriptionList,
		size_t	subscriptionCount,
		const MQTTPropBuilder_t *	pUnsubscribeProperties,
		uint32_t *	pRemainingLength,
		uint32_t *	pPacketSize,
		uint32_t	maxPacketSize
	)

Get packet size and Remaining Length of an MQTT UNSUBSCRIBE packet.

This function must be called before MQTT_SerializeUnsubscribe in order to get the size of the MQTT UNSUBSCRIBE packet that is generated from the list of MQTTSubscribeInfo_t and MQTTPropBuilder_t (optional unsubscribe properties). The size of the MQTTFixedBuffer_t supplied to MQTT_SerializeUnsubscribe must be at least pPacketSize. The provided pSubscriptionList is valid for serialization with MQTT_SerializeUnsubscribe only if this function returns MQTTSuccess. The remaining length returned in pRemainingLength and the packet size returned in pPacketSize are valid only if this function returns MQTTSuccess.

Parameters

[in]	pSubscriptionList	List of MQTT subscription info.
[in]	subscriptionCount	The number of elements in pSubscriptionList.
[in]	pUnsubscribeProperties	MQTT UNSUBSCRIBE properties builder. Pass NULL if not used.
[out]	pRemainingLength	The Remaining Length of the MQTT UNSUBSCRIBE packet.
[out]	pPacketSize	The total size of the MQTT UNSUBSCRIBE packet.
[in]	maxPacketSize	Maximum packet size.

Returns

MQTTBadParameter if the packet would exceed the size allowed by the MQTT spec; MQTTSuccess otherwise.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTSubscribeInfo_t subscriptionList[ NUMBER_OF_SUBSCRIPTIONS ] = { 0 };
size_t remainingLength = 0, packetSize = 0;
MQTTPropBuilder_t unsubscribeProperties = { 0 };
size_t maxPacketSize = 0;
 
// Initialize maxPacketSize. The details are out of scope for this example.
initializeMaxPacketSize( &maxPacketSize );
 
// Initialize the subscribe info. The details are out of scope for this example.
initializeSubscribeInfo( &subscriptionList[ 0 ] );
 
//Initialize the property buffer. The details are out of scope for this example.
initializePropertyBuffer( &unsubscribeProperties );
 
// Get the size requirement for the unsubscribe packet.
status = MQTT_GetUnsubscribePacketSize(
     &subscriptionList[ 0 ],
     NUMBER_OF_SUBSCRIPTIONS,
     &unsubscribeProperties,
     &remainingLength,
     &packetSize,
     maxPacketSize);
 
if( status == MQTTSuccess )
{
     // The unsubscribe packet can now be sent to the broker.
}

MQTT_ValidateUnsubscribeProperties()

MQTTStatus_t MQTT_ValidateUnsubscribeProperties

(

const MQTTPropBuilder_t *

pPropertyBuilder

)

Validates the properties specified for an MQTT UNSUBSCRIBE packet.

Parameters

[in]

pPropertyBuilder

Pointer to the property builder structure containing unsubscribe properties.

Returns

Returns one of the following:

• MQTTSuccess , MQTTBadParameter or MQTTBadResponse.

MQTT_SerializeUnsubscribe()

MQTTStatus_t MQTT_SerializeUnsubscribe	(	const MQTTSubscribeInfo_t *	pSubscriptionList,
		size_t	subscriptionCount,
		const MQTTPropBuilder_t *	pUnsubscribeProperties,
		uint16_t	packetId,
		uint32_t	remainingLength,
		const MQTTFixedBuffer_t *	pFixedBuffer
	)

Serialize an MQTT UNSUBSCRIBE packet with properties in the given buffer.

MQTT_GetUnsubscribePacketSize should be called with pSubscriptionList and pUnsubscribeProperties before invoking this function to get the size of the required MQTTFixedBuffer_t and remainingLength. The remainingLength must be the same as returned by MQTT_GetUnsubscribePacketSize. The MQTTFixedBuffer_t must be at least as large as the size returned by MQTT_GetUnsubscribePacketSize.

Parameters

[in]	pSubscriptionList	List of MQTT subscription info to unsubscribe from.
[in]	subscriptionCount	The number of elements in pSubscriptionList.
[in]	pUnsubscribeProperties	MQTT 5.0 properties for the UNSUBSCRIBE packet. Can be NULL if no properties are needed.
[in]	packetId	Packet identifier used for the UNSUBSCRIBE packet.
[in]	remainingLength	Remaining Length provided by MQTT_GetUnsubscribePacketSize.
[out]	pFixedBuffer	Buffer where the serialized UNSUBSCRIBE packet will be written.

Returns

MQTTNoMemory if pFixedBuffer is too small to hold the MQTT packet; MQTTBadParameter if any of the parameters are invalid (NULL pSubscriptionList or pFixedBuffer, zero subscriptionCount); MQTTSuccess if the packet was serialized successfully.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTSubscribeInfo_t subscriptionList[2];
MQTTPropBuilder_t unsubscribeProperties;
MQTTFixedBuffer_t fixedBuffer;
uint8_t buffer[100];
size_t remainingLength = 0, packetSize = 0;
uint16_t packetId = 1;
 
// Initialize the fixed buffer.
fixedBuffer.pBuffer = buffer;
fixedBuffer.size = sizeof( buffer );
 
// Initialize subscription list.
subscriptionList[0].pTopicFilter = "topic/1";
subscriptionList[0].topicFilterLength = strlen("topic/1");
subscriptionList[1].pTopicFilter = "topic/2";
subscriptionList[1].topicFilterLength = strlen("topic/2");
 
// Initialize properties (optional)
 
// Get size requirement for the unsubscribe packet.
status = MQTT_GetUnsubscribePacketSize(
     subscriptionList,
     2,
     &unsubscribeProperties,
     &remainingLength,
     &packetSize
);
 
if( status == MQTTSuccess )
{
     // Serialize unsubscribe packet.
     status = MQTT_SerializeUnsubscribe(
         subscriptionList,
         2,
         &unsubscribeProperties,
         packetId,
         remainingLength,
         &fixedBuffer
     );
}
 
if( status == MQTTSuccess )
{
     // The unsubscribe packet has been serialized successfully.
     // The serialized packet is now ready to be sent to the broker.
}

MQTT_GetPublishPacketSize()

MQTTStatus_t MQTT_GetPublishPacketSize	(	const MQTTPublishInfo_t *	pPublishInfo,
		const MQTTPropBuilder_t *	pPublishProperties,
		uint32_t *	pRemainingLength,
		uint32_t *	pPacketSize,
		uint32_t	maxPacketSize
	)

Get the packet size and remaining length of an MQTT PUBLISH packet.

MQTT_ValidatePublishParams should be called with pPublishInfo before invoking this function to validate the publish parameters. This function must be called before sendPublishWithoutCopy in order to get the size of the MQTT PUBLISH packet that is generated from MQTTPublishInfo_t and optional publish properties. The remaining length returned in pRemainingLength and the packet size returned in pPacketSize are valid only if this function returns MQTTSuccess.

Parameters

[in]	pPublishInfo	MQTT PUBLISH packet parameters.
[in]	pPublishProperties	MQTT PUBLISH properties builder. Pass NULL if not used.
[out]	pRemainingLength	The Remaining Length of the MQTT PUBLISH packet.
[out]	pPacketSize	The total size of the MQTT PUBLISH packet.
[in]	maxPacketSize	Maximum packet size allowed by the server.

Returns

MQTTBadParameter if the packet would exceed the size allowed by the MQTT spec or if invalid parameters are passed; MQTTSuccess otherwise.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTPublishInfo_t publishInfo = { 0 };
MQTTPropBuilder_t publishProperties = { 0 };
uint16_t topicAliasMax;
uint8_t retainAvailable;
uint8_t maxQos;
size_t remainingLength = 0, packetSize = 0;
 
// Initialize the publish info.
publishInfo.qos = MQTTQoS0;
publishInfo.pTopicName = "/some/topic/name";
publishInfo.topicNameLength = strlen( publishInfo.pTopicName );
publishInfo.pPayload = "Hello World!";
publishInfo.payloadLength = strlen( "Hello World!" );
 
// Initialize publish properties (if needed)
initializePublishProperties( &publishProperties );
 
// Validate publish parameters
status = MQTT_ValidatePublishParams(&publishInfo, topicAliasMax, retainAvailable, maxQos);
 
// Get the size requirement for the publish packet.
status = MQTT_GetPublishPacketSize(
     &publishInfo,
     &publishProperties,
     &remainingLength,
     &packetSize,
     maxPacketSize
);
 
if( status == MQTTSuccess )
{
     // The publish packet can now be sent to the broker.
}

MQTT_SerializePublish()

MQTTStatus_t MQTT_SerializePublish	(	const MQTTPublishInfo_t *	pPublishInfo,
		const MQTTPropBuilder_t *	pPublishProperties,
		uint16_t	packetId,
		uint32_t	remainingLength,
		const MQTTFixedBuffer_t *	pFixedBuffer
	)

Serialize an MQTT PUBLISH packet in the given buffer.

This function will serialize complete MQTT PUBLISH packet into the given buffer. If the PUBLISH payload can be sent separately, consider using MQTT_SerializePublishHeader, which will serialize only the PUBLISH header into the buffer.

MQTT_GetPublishPacketSize should be called with pPublishInfo before invoking this function to get the size of the required MQTTFixedBuffer_t and remainingLength. The remainingLength must be the same as returned by MQTT_GetPublishPacketSize. The MQTTFixedBuffer_t must be at least as large as the size returned by MQTT_GetPublishPacketSize.

Parameters

[in]	pPublishInfo	MQTT PUBLISH packet parameters.
[in]	pPublishProperties	MQTT v5.0 properties for the PUBLISH packet. Can be NULL if no properties are needed.
[in]	packetId	packet ID generated by MQTT_GetPacketId.
[in]	remainingLength	Remaining Length provided by MQTT_GetPublishPacketSize.
[out]	pFixedBuffer	Buffer for packet serialization.

Returns

MQTTNoMemory if pFixedBuffer is too small to hold the MQTT packet; MQTTBadParameter if invalid parameters are passed; MQTTSuccess otherwise.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTPublishInfo_t publishInfo = { 0 };
MQTTPropBuilder_t publishProperties = { 0 };
MQTTFixedBuffer_t fixedBuffer;
uint8_t buffer[ BUFFER_SIZE ];
size_t remainingLength = 0, packetSize = 0;
uint16_t packetId;
 
fixedBuffer.pBuffer = buffer;
fixedBuffer.size = BUFFER_SIZE;
 
// A packet identifier is unused for QoS 0 publishes. Otherwise, a valid, unused packet
// identifier must be used.
packetId = 0;
 
// Assume publishInfo and publishProperties have been initialized. Get publish packet size.
status = MQTT_GetPublishPacketSize(
     &publishInfo, &publishProperties, &remainingLength, &packetSize
);
assert( status == MQTTSuccess );
assert( packetSize <= BUFFER_SIZE );
 
// Serialize the publish packet into the fixed buffer.
status = MQTT_SerializePublish(
     &publishInfo,
     &publishProperties,
     packetId,
     remainingLength,
     &fixedBuffer
);
 
if( status == MQTTSuccess )
{
     // The publish packet can now be sent to the broker.
}

MQTT_SerializePublishHeader()

MQTTStatus_t MQTT_SerializePublishHeader	(	const MQTTPublishInfo_t *	pPublishInfo,
		const MQTTPropBuilder_t *	pPublishProperties,
		uint16_t	packetId,
		uint32_t	remainingLength,
		const MQTTFixedBuffer_t *	pFixedBuffer,
		size_t *	pHeaderSize
	)

Serialize an MQTT PUBLISH packet header in the given buffer.

This function serializes PUBLISH header in to the given buffer. The payload for PUBLISH will not be copied over to the buffer. This will help reduce the memory needed for the buffer and avoid an unwanted copy operation of the PUBLISH payload into the buffer. If the payload also would need to be part of the serialized buffer, consider using MQTT_SerializePublish.

MQTT_GetPublishPacketSize should be called with pPublishInfo before invoking this function to get the size of the required MQTTFixedBuffer_t and remainingLength. The remainingLength must be the same as returned by MQTT_GetPublishPacketSize. The MQTTFixedBuffer_t must be at least as large as the size returned by MQTT_GetPublishPacketSize.

Parameters

[in]	pPublishInfo	MQTT PUBLISH packet parameters.
[in]	pPublishProperties	MQTT v5.0 properties for the PUBLISH packet. Can be NULL if no properties are needed.
[in]	packetId	packet ID generated by MQTT_GetPacketId.
[in]	remainingLength	Remaining Length provided by MQTT_GetPublishPacketSize.
[out]	pFixedBuffer	Buffer for packet serialization.
[out]	pHeaderSize	Size of the serialized MQTT PUBLISH header.

Returns

MQTTNoMemory if pFixedBuffer is too small to hold the MQTT packet; MQTTBadParameter if invalid parameters are passed; MQTTSuccess otherwise.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTPublishInfo_t publishInfo = { 0 };
MQTTPropBuilder_t publishProperties ;
MQTTFixedBuffer_t fixedBuffer;
uint8_t buffer[ BUFFER_SIZE ];
size_t remainingLength = 0, packetSize = 0, headerSize = 0;
uint16_t packetId;
int32_t bytesSent;
uint32_t maxPacketSize = pContext->connectionProperties.serverMaxPacketSize;
 
fixedBuffer.pBuffer = buffer;
fixedBuffer.size = BUFFER_SIZE;
 
// A packet identifier is unused for QoS 0 publishes. Otherwise, a valid, unused packet
// identifier must be used.
packetId = 0;
 
// Assume publishInfo and publishProperties have been initialized. Get the publish packet size.
status = MQTT_GetPublishPacketSize(
     &publishInfo, &publishProperties, &remainingLength, &packetSize, maxPacketSize );
assert( status == MQTTSuccess );
// The payload will not be serialized, so the the fixed buffer does not need to hold it.
assert( ( packetSize - publishInfo.payloadLength ) <= BUFFER_SIZE );
 
// Serialize the publish packet header into the fixed buffer.
status = MQTT_SerializePublishHeader(
     &publishInfo,
     &publishProperties,
     packetId,
     remainingLength,
     &fixedBuffer,
     &headerSize
);
 
if( status == MQTTSuccess )
{
     // The publish header and payload can now be sent to the broker.
     // mqttSocket here is a socket descriptor created and connected to the MQTT
     // broker outside of this function.
     bytesSent = send( mqttSocket, ( void * ) fixedBuffer.pBuffer, headerSize, 0 );
     assert( bytesSent == headerSize );
     bytesSent = send( mqttSocket, publishInfo.pPayload, publishInfo.payloadLength, 0 );
     assert( bytesSent == publishInfo.payloadLength );
}

MQTT_SerializeAck()

MQTTStatus_t MQTT_SerializeAck	(	const MQTTFixedBuffer_t *	pFixedBuffer,
		uint8_t	packetType,
		uint16_t	packetId,
		const MQTTPropBuilder_t *	pAckProperties,
		const MQTTSuccessFailReasonCode_t *	pReasonCode
	)

Serialize an MQTT PUBACK, PUBREC, PUBREL, or PUBCOMP into the given buffer.

Parameters

[out]	pFixedBuffer	Buffer for packet serialization.
[in]	packetType	Byte of the corresponding packet fixed header per the MQTT spec.
[in]	packetId	Packet ID of the publish.
[in]	pAckProperties	Optional properties to be added to the ACK packet.
[in]	pReasonCode	Optional reason code to be added to the ACK packet.

Note

If any properties are provided to the function to be added to the ack packet, then a reason code must be provided as well.

Returns

MQTTBadParameter, MQTTNoMemory, or MQTTSuccess.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTFixedBuffer_t fixedBuffer;
uint8_t buffer[ BUFFER_SIZE ];
uint16_t packetId;
uint8_t packetType;
 
fixedBuffer.pBuffer = buffer;
fixedBuffer.size = BUFFER_SIZE;
// The fixed buffer must be large enough to hold 4 bytes.
assert( BUFFER_SIZE >= MQTT_PUBLISH_ACK_PACKET_SIZE );
 
// The packet ID must be the same as the original publish packet.
packetId = publishPacketId;
 
// The byte representing a packet of type ACK. This function accepts PUBACK, PUBREC, PUBREL, or PUBCOMP.
packetType = MQTT_PACKET_TYPE_PUBACK;
 
// Serialize the publish acknowledgment into the fixed buffer without any properties or reason code.
status = MQTT_SerializeAck( &fixedBuffer, packetType, packetId, NULL, NULL );
 
if( status == MQTTSuccess )
{
     // The publish acknowledgment can now be sent to the broker.
}

MQTT_GetDisconnectPacketSize()

MQTTStatus_t MQTT_GetDisconnectPacketSize	(	const MQTTPropBuilder_t *	pDisconnectProperties,
		uint32_t *	pRemainingLength,
		uint32_t *	pPacketSize,
		uint32_t	maxPacketSize,
		const MQTTSuccessFailReasonCode_t *	pReasonCode
	)

Get the size of an MQTT DISCONNECT packet.

Parameters

[in]	pDisconnectProperties	MQTT DISCONNECT properties builder. Pass NULL if not used.
[out]	pRemainingLength	The Remaining Length of the MQTT DISCONNECT packet.
[out]	pPacketSize	The size of the MQTT DISCONNECT packet.
[in]	maxPacketSize	Maximum packet size allowed by the server.
[in]	pReasonCode	The reason code for the disconnect. Pass NULL if not used - only valid if the properties are NULL too.

Returns

MQTTSuccess, or MQTTBadParameter if parameters are invalid

Example

// Variables used in this example.
MQTTStatus_t status;
uint32_t remainingLength = 0;
uint32_t packetSize = 0;
uint32_t maxPacketSize;
MQTTPropBuilder_t disconnectProperties ;
MQTTSuccessFailReasonCode_t reasonCode = MQTT_REASON_DISCONNECT_NORMAL_DISCONNECTION;
 
//Set property builder. The details are out of scope for this example.
initializePropertyBuilder( &disconnectProperties );
 
//Set the parameters.
// Get the size requirement for the disconnect packet.
status = MQTT_GetDisconnectPacketSize( &disconnectProperties, &remainingLength, &packetSize, maxPacketSize, &reasonCode );
 
if( status == MQTTSuccess )
{
     // Send the disconnect packet.
}

MQTT_SerializeDisconnect()

MQTTStatus_t MQTT_SerializeDisconnect	(	const MQTTPropBuilder_t *	pDisconnectProperties,
		const MQTTSuccessFailReasonCode_t *	pReasonCode,
		uint32_t	remainingLength,
		const MQTTFixedBuffer_t *	pFixedBuffer
	)

Serialize an MQTT DISCONNECT packet into the given buffer.

The input MQTTFixedBuffer_t.size must be at least as large as the size returned by MQTT_GetDisconnectPacketSize. This function should only be called after MQTT_GetDisconnectPacketSize to ensure proper buffer sizing.

Parameters

[in]	pDisconnectProperties	MQTT v5.0 properties for the DISCONNECT packet. Can be NULL if no properties are needed.
[in]	pReasonCode	The reason code for the disconnect. For MQTT v5.0, this indicates why the connection is being terminated. If this is NULL, then the pDisconnectProperties must be NULL as well.
[in]	remainingLength	Remaining Length provided by MQTT_GetDisconnectPacketSize.
[out]	pFixedBuffer	Buffer for packet serialization.

Returns

MQTTNoMemory if pFixedBuffer is too small to hold the MQTT packet; MQTTBadParameter if invalid parameters are passed; MQTTSuccess otherwise.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTFixedBuffer_t fixedBuffer;
MQTTPropBuilder_t disconnectProperties = { 0 };
uint8_t buffer[ BUFFER_SIZE ];
uint32_t remainingLength = 0, packetSize = 0;
 
fixedBuffer.pBuffer = buffer;
fixedBuffer.size = BUFFER_SIZE;
 
MQTTSuccessFailReasonCode_t reasonCode = MQTT_REASON_DISCONNECT_NORMAL_DISCONNECTION;
// Get the disconnect packet size.
status = MQTT_GetDisconnectPacketSize( &disconnectProperties,
                                       &remainingLength,
                                       &packetSize,
                                       MQTT_MAX_REMAINING_LENGTH,
                                       &reasonCode );
assert( status == MQTTSuccess );
assert( packetSize <= BUFFER_SIZE );
 
// Serialize the disconnect into the fixed buffer.
status = MQTT_SerializeDisconnect( &disconnectProperties,
                                  &reasonCode,
                                  remainingLength,
                                  &fixedBuffer );
 
if( status == MQTTSuccess )
{
     // The disconnect packet can now be sent to the broker.
}

MQTT_GetPingreqPacketSize()

MQTTStatus_t MQTT_GetPingreqPacketSize

(

uint32_t *

pPacketSize

)

Get the size of an MQTT PINGREQ packet.

Parameters

[out]

pPacketSize

The size of the MQTT PINGREQ packet.

Returns

MQTTSuccess or MQTTBadParameter if pPacketSize is NULL.

Example

// Variables used in this example.
MQTTStatus_t status;
uint32_t packetSize = 0;
 
// Get the size requirement for the ping request packet.
status = MQTT_GetPingreqPacketSize( &packetSize );
assert( status == MQTTSuccess );
assert( packetSize == 2 );
 
// The application should allocate or use a static #MQTTFixedBuffer_t of
// size >= 2 to serialize the ping request.

MQTT_SerializePingreq()

MQTTStatus_t MQTT_SerializePingreq

(

const MQTTFixedBuffer_t *

pFixedBuffer

)

Serialize an MQTT PINGREQ packet into the given buffer.

The input MQTTFixedBuffer_t.size must be at least as large as the size returned by MQTT_GetPingreqPacketSize.

Parameters

[out]

pFixedBuffer

Buffer for packet serialization.

Returns

MQTTNoMemory if pFixedBuffer is too small to hold the MQTT packet; MQTTBadParameter if invalid parameters are passed; MQTTSuccess otherwise.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTFixedBuffer_t fixedBuffer;
uint8_t buffer[ BUFFER_SIZE ];
 
fixedBuffer.pBuffer = buffer;
fixedBuffer.size = BUFFER_SIZE;
 
// Get the ping request packet size.
status = MQTT_GetPingreqPacketSize( &packetSize );
assert( status == MQTTSuccess );
assert( packetSize <= BUFFER_SIZE );
 
// Serialize the ping request into the fixed buffer.
status = MQTT_SerializePingreq( &fixedBuffer );
 
if( status == MQTTSuccess )
{
     // The ping request can now be sent to the broker.
}

MQTT_DeserializePublish()

MQTTStatus_t MQTT_DeserializePublish	(	const MQTTPacketInfo_t *	pIncomingPacket,
		uint16_t *	pPacketId,
		MQTTPublishInfo_t *	pPublishInfo,
		MQTTPropBuilder_t *	propBuffer,
		uint32_t	maxPacketSize,
		uint16_t	topicAliasMax
	)

Deserialize an MQTT PUBLISH packet.

Parameters

[in]	pIncomingPacket	MQTTPacketInfo_t containing the buffer.
[out]	pPacketId	The packet ID obtained from the buffer.
[out]	pPublishInfo	Struct containing information about the publish.
[in]	propBuffer	Buffer to hold the properties.
[in]	maxPacketSize	Maximum packet size.
[in]	topicAliasMax	Maximum topic alias specified in the CONNECT packet.

Returns

• MQTTBadParameter if invalid parameters are passed
• MQTTBadResponse if invalid packet is read
• MQTTSuccess otherwise.

Example

// TransportRecv_t function for reading from the network.
int32_t socket_recv(
     NetworkContext_t * pNetworkContext,
     void * pBuffer,
     size_t bytesToRecv
);
// Some context to be used with the above transport receive function.
NetworkContext_t networkContext;
 
// Other variables used in this example.
MQTTStatus_t status;
MQTTPacketInfo_t incomingPacket;
MQTTPublishInfo_t publishInfo = { 0 };
MQTTPropBuilder_t propBuffer ;
uint16_t packetId;
uint32_t maxPacketSize = pContext->connectionProperties.maxPacketSize;
uint16_t topicAliasMax = pContext->connectionProperties.topicAliasMax;
 
int32_t bytesRecvd;
// A buffer to hold remaining data of the incoming packet.
uint8_t buffer[ BUFFER_SIZE ];
 
// Populate all fields of the incoming packet.
status = MQTT_GetIncomingPacketTypeAndLength(
     socket_recv,
     &networkContext,
     &incomingPacket
);
assert( status == MQTTSuccess );
assert( incomingPacket.remainingLength <= BUFFER_SIZE );
bytesRecvd = socket_recv(
     &networkContext,
     ( void * ) buffer,
     incomingPacket.remainingLength
);
incomingPacket.pRemainingData = buffer;
 
// Deserialize the publish information if the incoming packet is a publish.
if( ( incomingPacket.type & 0xF0 ) == MQTT_PACKET_TYPE_PUBLISH )
{
     status = MQTT_DeserializePublish( &incomingPacket, &packetId, &publishInfo,
                                       &propBuffer, maxPacketSize, topicAliasMax );
     if( status == MQTTSuccess )
     {
         // The deserialized publish information can now be used from `publishInfo`.
     }
}

MQTT_DeserializeConnAck()

MQTTStatus_t MQTT_DeserializeConnAck	(	const MQTTPacketInfo_t *	pIncomingPacket,
		bool *	pSessionPresent,
		MQTTPropBuilder_t *	pPropBuffer,
		MQTTConnectionProperties_t *	pConnectProperties
	)

Deserialize an MQTT CONNACK.

Parameters

[in]	pIncomingPacket	MQTTPacketInfo_t containing the buffer.
[out]	pSessionPresent	Boolean flag from a CONNACK indicating present session.
[out]	pPropBuffer	Struct to store the deserialized acknowledgment properties. Will contain any MQTT v5.0 properties included in the ack packet.
[in,out]	pConnectProperties	Struct to store the deserialized connect/connack properties. This parameter cannot be NULL.

Returns

MQTTBadParameter, MQTTBadResponse, MQTTServerRefused, or MQTTSuccess.

MQTT_DeserializeAck()

MQTTStatus_t MQTT_DeserializeAck	(	const MQTTPacketInfo_t *	pIncomingPacket,
		uint16_t *	pPacketId,
		MQTTReasonCodeInfo_t *	pReasonCode,
		MQTTPropBuilder_t *	pPropBuffer,
		const MQTTConnectionProperties_t *	pConnectProperties
	)

Deserialize an MQTT PUBACK, PUBREC, PUBREL, PUBCOMP, SUBACK, UNSUBACK, or PINGRESP.

Parameters

[in]	pIncomingPacket	MQTTPacketInfo_t containing the buffer.
[out]	pPacketId	The packet ID obtained from the buffer.
[out]	pReasonCode	Struct to store reason code(s) from the acknowledgment packet. Contains the success/failure status of the corresponding request.
[out]	pPropBuffer	Struct to store the deserialized acknowledgment properties. Will contain any MQTT v5.0 properties included in the ack packet.
[in,out]	pConnectProperties	Struct to store the deserialized connect/connack properties.

Returns

Returns one of the following:

• MQTTSuccess if the packet was successfully deserialized
• MQTTBadParameter if invalid parameters are passed
• MQTTServerRefused if the server explicitly rejected the request, either in the CONNACK or a SUBACK.
• MQTTBadResponse if the packet type is invalid or packet parsing fails

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTPacketInfo_t incomingPacket;
uint16_t packetId;
MQTTReasonCodeInfo_t reasonCode ; // Can be set to NULL if the incoming packet is CONNACK or PINGRESP
MQTTPropBuilder_t propBuffer; // Can be set to NULL if the user does not want any incoming properties.
MQTTConnectionProperties_t connectionProperties = pContext->connectionProperties;  // Cannot be set to NULL.
 
// Receive an incoming packet and populate all fields. The details are out of scope
// for this example.
receiveIncomingPacket(&incomingPacket);
 
// Deserialize ack information if the incoming packet is a publish ack.
status = MQTT_DeserializeAck( &incomingPacket,
                              &packetId,
                              &reasonCode,
                              &propBuffer,
                              &connectionProperties );
if(status == MQTTSuccess)
{
    // Ack information is now available.
}

MQTT_GetIncomingPacketTypeAndLength()

MQTTStatus_t MQTT_GetIncomingPacketTypeAndLength	(	TransportRecv_t	readFunc,
		NetworkContext_t *	pNetworkContext,
		MQTTPacketInfo_t *	pIncomingPacket
	)

Extract the MQTT packet type and length from incoming packet.

This function must be called for every incoming packet to retrieve the MQTTPacketInfo_t.type and MQTTPacketInfo_t.remainingLength. A MQTTPacketInfo_t is not valid until this routine has been invoked.

Parameters

[in]	readFunc	Transport layer read function pointer.
[in]	pNetworkContext	The network context pointer provided by the application.
[out]	pIncomingPacket	Pointer to MQTTPacketInfo_t structure. This is where type, remaining length and packet identifier are stored.

Returns

MQTTSuccess on successful extraction of type and length, MQTTBadParameter if pIncomingPacket is invalid, MQTTRecvFailed on transport receive failure, MQTTBadResponse if an invalid packet is read, and MQTTNoDataAvailable if there is nothing to read.

Example

// TransportRecv_t function for reading from the network.
int32_t socket_recv(
     NetworkContext_t * pNetworkContext,
     void * pBuffer,
     size_t bytesToRecv
);
// Some context to be used with above transport receive function.
NetworkContext_t networkContext;
 
// Struct to hold the incoming packet information.
MQTTPacketInfo_t incomingPacket;
MQTTStatus_t status = MQTTSuccess;
int32_t bytesRecvd;
// Buffer to hold the remaining data of the incoming packet.
uint8_t buffer[ BUFFER_SIZE ];
 
// Loop until data is available to be received.
do{
     status = MQTT_GetIncomingPacketTypeAndLength(
         socket_recv,
         &networkContext,
         &incomingPacket
     );
} while( status == MQTTNoDataAvailable );
 
assert( status == MQTTSuccess );
 
// Receive the rest of the incoming packet.
assert( incomingPacket.remainingLength <= BUFFER_SIZE );
bytesRecvd = socket_recv(
     &networkContext,
     ( void * ) buffer,
     incomingPacket.remainingLength
);
 
// Set the remaining data field.
incomingPacket.pRemainingData = buffer;

MQTT_UpdateDuplicatePublishFlag()

MQTTStatus_t MQTT_UpdateDuplicatePublishFlag	(	uint8_t *	pHeader,
		bool	set
	)

Update the duplicate publish flag within the given header of the publish packet.

Parameters

[in]	pHeader	The buffer holding the header content
[in]	set	If true then the flag will be set else cleared

Returns

MQTTSuccess on successful setting of the duplicate flag, MQTTBadParameter for invalid parameters

MQTT_ProcessIncomingPacketTypeAndLength()

MQTTStatus_t MQTT_ProcessIncomingPacketTypeAndLength	(	const uint8_t *	pBuffer,
		const size_t *	pIndex,
		MQTTPacketInfo_t *	pIncomingPacket
	)

Extract the MQTT packet type and length from incoming packet.

This function must be called for every incoming packet to retrieve the MQTTPacketInfo_t.type and MQTTPacketInfo_t.remainingLength. A MQTTPacketInfo_t is not valid until this routine has been invoked.

Parameters

[in]	pBuffer	The buffer holding the raw data to be processed
[in]	pIndex	Pointer to the index within the buffer to marking the end of raw data available.
[out]	pIncomingPacket	Structure used to hold the fields of the incoming packet.

Returns

MQTTSuccess on successful extraction of type and length, MQTTBadParameter if pIncomingPacket is invalid, MQTTBadResponse if an invalid packet is read, and MQTTNoDataAvailable if there is nothing to read.

MQTT_InitConnect()

MQTTStatus_t MQTT_InitConnect

(

MQTTConnectionProperties_t *

pConnectProperties

)

Initialize an MQTTConnectionProperties_t.

Note

This function initializes the connect properties to default values. This function should only be used if using only serializer functions throughout the connection. It is also important to only call this function before sending the connect packet.

Parameters

[in]

pConnectProperties

The connect properties to initialize.

Returns

• MQTTBadParameter if pConnectProperties is NULL.
• MQTTSuccess otherwise.

MQTTPropertyBuilder_Init()

MQTTStatus_t MQTTPropertyBuilder_Init	(	MQTTPropBuilder_t *	pPropertyBuilder,
		uint8_t *	buffer,
		size_t	length
	)

Initialize the property builder.

Parameters

[out]	pPropertyBuilder	Property builder to initialize.
[in]	buffer	Buffer to store the properties.
[in]	length	Length of the buffer.

Returns

• MQTTBadParameter if invalid parameters are passed.
• MQTTSuccess otherwise.

MQTT_ValidateWillProperties()

MQTTStatus_t MQTT_ValidateWillProperties

(

const MQTTPropBuilder_t *

pPropertyBuilder

)

Validates the properties specified for WILL Properties in the MQTT CONNECT packet.

Parameters

[in]

pPropertyBuilder

Pointer to the property builder structure containing will properties.

Returns

Returns one of the following:

• MQTTSuccess , MQTTBadParameter or MQTTBadResponse.

MQTT_ValidateConnectProperties()

MQTTStatus_t MQTT_ValidateConnectProperties	(	const MQTTPropBuilder_t *	pPropertyBuilder,
		bool *	isRequestProblemInfoSet,
		uint32_t *	pPacketMaxSizeValue
	)

Validate the properties in a CONNECT packet.

Parameters

[in]	pPropertyBuilder	Pointer to the property builder structure containing connect packet properties.
[out]	isRequestProblemInfoSet	Whether the request problem info field is set in the properties.
[out]	pPacketMaxSizeValue	Optional pointer to get the Maximum Packet Size from the properties. If not required, NULL can be passed.

Returns

Returns one of the following:

• MQTTSuccess , MQTTBadParameter or MQTTBadResponse.

MQTT_ValidateSubscribeProperties()

MQTTStatus_t MQTT_ValidateSubscribeProperties	(	bool	isSubscriptionIdAvailable,
		const MQTTPropBuilder_t *	propBuilder
	)

Validates the properties of a SUBSCRIBE packet.

This function validates the properties in the property builder for a SUBSCRIBE packet.

Parameters

[in]	isSubscriptionIdAvailable	Boolean indicating if subscription identifiers are supported.
[in]	propBuilder	Pointer to the property builder structure.

Returns

Returns one of the following:

• MQTTSuccess if the properties are valid
• MQTTBadParameter if an invalid parameter is passed

MQTT_ValidatePublishProperties()

MQTTStatus_t MQTT_ValidatePublishProperties	(	uint16_t	serverTopicAliasMax,
		const MQTTPropBuilder_t *	propBuilder,
		uint16_t *	topicAlias
	)

Validates the properties of a PUBLISH packet.

This function validates the properties in the property builder for a PUBLISH packet.

Parameters

[in]	serverTopicAliasMax	Maximum topic alias value allowed by the server.
[in]	propBuilder	Pointer to the property builder structure.
[out]	topicAlias	Pointer to store the topic alias value if present.

Returns

Returns one of the following:

• MQTTSuccess if the properties are valid
• MQTTBadParameter if invalid parameters are passed
• MQTTBadResponse if an invalid packet is read

MQTT_ValidatePublishParams()

MQTTStatus_t MQTT_ValidatePublishParams	(	const MQTTPublishInfo_t *	pPublishInfo,
		uint8_t	retainAvailable,
		uint8_t	maxQos,
		uint16_t	topicAlias,
		uint32_t	maxPacketSize
	)

Validate the publish parameters present in the given publish structure pPublishInfo.

This function must be called before MQTT_GetPublishPacketSize in order to validate the publish parameters.

Parameters

[in]	pPublishInfo	MQTT publish packet parameters.
[in]	retainAvailable	Whether server allows retain or not.
[in]	maxQos	Maximum QoS supported by the server.
[in]	topicAlias	Topic alias in the PUBLISH packet.
[in]	maxPacketSize	Maximum packet size allowed by the server.

Returns

MQTTBadParameter if invalid parameters are passed; MQTTSuccess otherwise.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTPublishInfo_t publishInfo = {0};
uint16_t topicAlias;
uint8_t retainAvailable;
uint8_t maxQos;
// Set in the CONNACK packet.
uint32_t maxPacketSize ;
 
//Set the publish info parameters.
 
//Validate the publish packet
status = MQTT_ValidatePublishParams(&publishInfo, retainAvailable, maxQos, topicAlias, maxPacketSize);
 
if( status == MQTTSuccess )
{
     // Get the packet size and serialize the publish packet.
}

MQTT_ValidatePublishAckProperties()

MQTTStatus_t MQTT_ValidatePublishAckProperties

(

const MQTTPropBuilder_t *

pPropertyBuilder

)

Validates the properties specified for an MQTT PUBLISH ACK packet.

Parameters

[in]

pPropertyBuilder

Pointer to the property builder structure containing unsubscribe properties.

Returns

Returns one of the following:

• MQTTSuccess , MQTTBadParameter or MQTTBadResponse.

MQTT_GetAckPacketSize()

MQTTStatus_t MQTT_GetAckPacketSize	(	uint32_t *	pRemainingLength,
		uint32_t *	pPacketSize,
		uint32_t	maxPacketSize,
		size_t	ackPropertyLength
	)

Get the size of an outgoing PUBLISH ACK packet.

Note

If no reason code is sent and property length is zero then MQTT_SerializeAck can be used directly.

Parameters

[out]	pRemainingLength	The remaining length of the packet to be serialized.
[out]	pPacketSize	The size of the packet to be serialized.
[in]	maxPacketSize	Maximum packet size allowed by the server.
[in]	ackPropertyLength	The length of the properties.

Returns

MQTTBadParameter if invalid parameters are passed; MQTTSuccess otherwise.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTFixedBuffer_t fixedBuffer;
uint8_t buffer[ BUFFER_SIZE ];
MQTTAckInfo_t  ackInfo;
uint16_t sessionExpiry;
 
fixedBuffer.pBuffer = buffer;
fixedBuffer.size = BUFFER_SIZE;
// Variables used in this example.
MQTTStatus_t status;
size_t remainingLength =0;
size_t packetSize = 0;
size_t ackPropertyLength = 0;
uint32_t maxPacketSize;
//set the parameters.
// Get the size requirement for the ack packet.
status = MQTT_GetAckPacketSize(&remainingLength,&packetSize,maxPacketSize, ackPropertyLength);
}

MQTT_ValidateDisconnectProperties()

MQTTStatus_t MQTT_ValidateDisconnectProperties	(	uint32_t	connectSessionExpiry,
		const MQTTPropBuilder_t *	pPropertyBuilder
	)

Validates the properties specified for an MQTT DISCONNECT packet.

Parameters

[in]	connectSessionExpiry	The session expiry interval that was specified in the CONNECT packet. Used to validate that the DISCONNECT session expiry is not non-zero while connectSessionExpiry is zero.
[in]	pPropertyBuilder	Pointer to the property builder structure containing subscribe properties.

Returns

Returns one of the following:

• MQTTSuccess , MQTTBadParameter or MQTTBadResponse.

MQTT_DeserializeDisconnect()

MQTTStatus_t MQTT_DeserializeDisconnect	(	const MQTTPacketInfo_t *	pPacket,
		uint32_t	maxPacketSize,
		MQTTReasonCodeInfo_t *	pDisconnectInfo,
		MQTTPropBuilder_t *	pPropBuffer
	)

Deserialize an MQTT Disconnect packet.

Parameters

[in]	pPacket	MQTTPacketInfo_t containing the buffer.
[in]	maxPacketSize	Maximum packet size allowed by the client.
[out]	pDisconnectInfo	Struct containing disconnect reason code
[out]	pPropBuffer	MQTTPropBuilder_t to store the deserialized properties.

Returns

MQTTBadParameter, MQTTBadResponse or MQTTSuccess.

Example

// Variables used in this example.
MQTTStatus_t status;
MQTTPacketInfo_t incomingPacket;
MQTTReasonCodeInfo_t disconnectInfo;
uint32_t maxPacketSize;
MQTTPropBuilder_t propBuffer; // Assume this is initialized properly
// Receive an incoming packet and populate all fields. The details are out of scope
// for this example.
receiveIncomingPacket( &incomingPacket );
 
// Deserialize disconnect information.
if( ( incomingPacket.type) == MQTT_PACKET_TYPE_DISCONNECT )
{
     status = MQTT_DeserializeDisconnect(&incomingPacket,
                                          maxPacketSize,
                                          &disconnectInfo,
                                          &propBuffer);
     if( status == MQTTSuccess )
     {
         // Disconnect information is available.
     }
}