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.
}