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shadow_demo_helpers.c
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/*
* AWS IoT Device SDK for Embedded C 202412.00
* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/**
* @file shadow_demo_helpers.c
*
* @brief This file provides helper functions used by shadow demo application to
* do MQTT operation based on mutually authenticated TLS connection.
*
* A mutually authenticated TLS connection is used to connect to the AWS IoT
* MQTT message broker in this example. Define ROOT_CA_CERT_PATH,
* CLIENT_CERT_PATH, and CLIENT_PRIVATE_KEY_PATH in demo_config.h to achieve
* mutual authentication.
*/
/* Standard includes. */
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
/* Shadow includes */
#include "shadow_demo_helpers.h"
/* POSIX includes. */
#include <unistd.h>
/* OpenSSL sockets transport implementation. */
#include "openssl_posix.h"
/*Include backoff algorithm header for retry logic.*/
#include "backoff_algorithm.h"
/* Clock for timer. */
#include "clock.h"
/* AWS IoT Core TLS ALPN definitions for MQTT authentication */
#include "aws_iot_alpn_defs.h"
/**
* These configuration settings are required to run the shadow demo.
* Throw compilation error if the below configs are not defined.
*/
#ifndef AWS_IOT_ENDPOINT
#error "Please define AWS IoT MQTT broker endpoint(AWS_IOT_ENDPOINT) in demo_config.h."
#endif
#ifndef ROOT_CA_CERT_PATH
#error "Please define path to Root CA certificate of the MQTT broker(ROOT_CA_CERT_PATH) in demo_config.h."
#endif
#ifndef CLIENT_CERT_PATH
#error "Please define path to client certificate(CLIENT_CERT_PATH) in demo_config.h."
#endif
#ifndef CLIENT_PRIVATE_KEY_PATH
#error "Please define path to client private key(CLIENT_PRIVATE_KEY_PATH) in demo_config.h."
#endif
#ifndef CLIENT_IDENTIFIER
#error "Please define a unique CLIENT_IDENTIFIER."
#endif
/**
* Provide default values for undefined configuration settings.
*/
#ifndef AWS_MQTT_PORT
#define AWS_MQTT_PORT ( 8883 )
#endif
#ifndef NETWORK_BUFFER_SIZE
#define NETWORK_BUFFER_SIZE ( 1024U )
#endif
/**
* @brief Length of MQTT server host name.
*/
#define AWS_IOT_ENDPOINT_LENGTH ( ( uint16_t ) ( sizeof( AWS_IOT_ENDPOINT ) - 1 ) )
/**
* @brief Length of client identifier.
*/
#define CLIENT_IDENTIFIER_LENGTH ( ( uint16_t ) ( sizeof( CLIENT_IDENTIFIER ) - 1 ) )
/**
* @brief The maximum number of retries for connecting to server.
*/
#define CONNECTION_RETRY_MAX_ATTEMPTS ( 5U )
/**
* @brief The maximum back-off delay (in milliseconds) for retrying connection to server.
*/
#define CONNECTION_RETRY_MAX_BACKOFF_DELAY_MS ( 5000U )
/**
* @brief The base back-off delay (in milliseconds) to use for connection retry attempts.
*/
#define CONNECTION_RETRY_BACKOFF_BASE_MS ( 500U )
/**
* @brief Timeout for receiving CONNACK packet in milli seconds.
*/
#define CONNACK_RECV_TIMEOUT_MS ( 1000U )
/**
* @brief Maximum number of outgoing publishes maintained in the application
* until an ack is received from the broker.
*/
#define MAX_OUTGOING_PUBLISHES ( 5U )
/**
* @brief Invalid packet identifier for the MQTT packets. Zero is always an
* invalid packet identifier as per MQTT 3.1.1 spec.
*/
#define MQTT_PACKET_ID_INVALID ( ( uint16_t ) 0U )
/**
* @brief Timeout for MQTT_ProcessLoop function in milliseconds.
*/
#define MQTT_PROCESS_LOOP_TIMEOUT_MS ( 1000U )
/**
* @brief The maximum time interval in seconds which is allowed to elapse
* between two Control Packets.
*
* It is the responsibility of the Client to ensure that the interval between
* Control Packets being sent does not exceed the this Keep Alive value. In the
* absence of sending any other Control Packets, the Client MUST send a
* PINGREQ Packet.
*/
#define MQTT_KEEP_ALIVE_INTERVAL_SECONDS ( 60U )
/**
* @brief Transport timeout in milliseconds for transport send and receive.
*/
#define TRANSPORT_SEND_RECV_TIMEOUT_MS ( 1000 )
/**
* @brief The MQTT metrics string expected by AWS IoT.
*/
#define METRICS_STRING "?SDK=" OS_NAME "&Version=" OS_VERSION "&Platform=" HARDWARE_PLATFORM_NAME "&MQTTLib=" MQTT_LIB
/**
* @brief The length of the MQTT metrics string expected by AWS IoT.
*/
#define METRICS_STRING_LENGTH ( ( uint16_t ) ( sizeof( METRICS_STRING ) - 1 ) )
/**
* @brief The length of the outgoing publish records array used by the coreMQTT
* library to track QoS > 0 packet ACKS for outgoing publishes.
*/
#define OUTGOING_PUBLISH_RECORD_LEN ( 10U )
/**
* @brief The length of the incoming publish records array used by the coreMQTT
* library to track QoS > 0 packet ACKS for incoming publishes.
*/
#define INCOMING_PUBLISH_RECORD_LEN ( 10U )
/*-----------------------------------------------------------*/
/**
* @brief Structure to keep the MQTT publish packets until an ack is received
* for QoS1 publishes.
*/
typedef struct PublishPackets
{
/**
* @brief Packet identifier of the publish packet.
*/
uint16_t packetId;
/**
* @brief Publish info of the publish packet.
*/
MQTTPublishInfo_t pubInfo;
} PublishPackets_t;
/*-----------------------------------------------------------*/
/* Each compilation unit must define the NetworkContext struct. */
struct NetworkContext
{
OpensslParams_t * pParams;
};
/*-----------------------------------------------------------*/
/**
* @brief Packet Identifier updated when an ACK packet is received.
*
* It is used to match an expected ACK for a transmitted packet.
*/
static uint16_t globalAckPacketIdentifier = 0U;
/**
* @brief Packet Identifier generated when Subscribe request was sent to the broker;
* it is used to match received Subscribe ACK to the transmitted subscribe.
*/
static uint16_t globalSubscribePacketIdentifier = 0U;
/**
* @brief Packet Identifier generated when Unsubscribe request was sent to the broker;
* it is used to match received Unsubscribe ACK to the transmitted unsubscribe
* request.
*/
static uint16_t globalUnsubscribePacketIdentifier = 0U;
/**
* @brief Array to keep the outgoing publish messages.
* These stored outgoing publish messages are kept until a successful ack
* is received.
*/
static PublishPackets_t outgoingPublishPackets[ MAX_OUTGOING_PUBLISHES ] = { 0 };
/**
* @brief The network buffer must remain valid for the lifetime of the MQTT context.
*/
static uint8_t buffer[ NETWORK_BUFFER_SIZE ];
/**
* @brief The MQTT context used for MQTT operation.
*/
static MQTTContext_t mqttContext = { 0 };
/**
* @brief The network context used for Openssl operation.
*/
static NetworkContext_t networkContext = { 0 };
/**
* @brief The parameters for Openssl operation.
*/
static OpensslParams_t opensslParams = { 0 };
/**
* @brief The flag to indicate the mqtt session changed.
*/
static bool mqttSessionEstablished = false;
/**
* @brief Array to track the outgoing publish records for outgoing publishes
* with QoS > 0.
*
* This is passed into #MQTT_InitStatefulQoS to allow for QoS > 0.
*
*/
static MQTTPubAckInfo_t pOutgoingPublishRecords[ OUTGOING_PUBLISH_RECORD_LEN ];
/**
* @brief Array to track the incoming publish records for incoming publishes
* with QoS > 0.
*
* This is passed into #MQTT_InitStatefulQoS to allow for QoS > 0.
*
*/
static MQTTPubAckInfo_t pIncomingPublishRecords[ INCOMING_PUBLISH_RECORD_LEN ];
/*-----------------------------------------------------------*/
/**
* @brief The random number generator to use for exponential backoff with
* jitter retry logic.
*
* @return The generated random number.
*/
static uint32_t generateRandomNumber();
/**
* @brief Connect to MQTT broker with reconnection retries.
*
* If connection fails, retry is attempted after a timeout.
* Timeout value will exponentially increase until maximum
* timeout value is reached or the number of attempts are exhausted.
*
* @param[out] pNetworkContext The output parameter to return the created network context.
*
* @return EXIT_FAILURE on failure; EXIT_SUCCESS on successful connection.
*/
static int connectToServerWithBackoffRetries( NetworkContext_t * pNetworkContext );
/**
* @brief Function to get the free index at which an outgoing publish
* can be stored.
*
* @param[out] pIndex The output parameter to return the index at which an
* outgoing publish message can be stored.
*
* @return EXIT_FAILURE if no more publishes can be stored;
* EXIT_SUCCESS if an index to store the next outgoing publish is obtained.
*/
static int getNextFreeIndexForOutgoingPublishes( uint8_t * pIndex );
/**
* @brief Function to clean up an outgoing publish at given index from the
* #outgoingPublishPackets array.
*
* @param[in] index The index at which a publish message has to be cleaned up.
*/
static void cleanupOutgoingPublishAt( uint8_t index );
/**
* @brief Function to clean up all the outgoing publishes maintained in the
* array.
*/
static void cleanupOutgoingPublishes( void );
/**
* @brief Function to clean up the publish packet with the given packet id.
*
* @param[in] packetId Packet identifier of the packet to be cleaned up from
* the array.
*/
static void cleanupOutgoingPublishWithPacketID( uint16_t packetId );
/**
* @brief Function to resend the publishes if a session is re-established with
* the broker. This function handles the resending of the QoS1 publish packets,
* which are maintained locally.
*
* @param[in] pMqttContext MQTT context pointer.
*/
static int handlePublishResend( MQTTContext_t * pMqttContext );
/**
* @brief Wait for an expected ACK packet to be received.
*
* This function handles waiting for an expected ACK packet by calling
* #MQTT_ProcessLoop and waiting for #mqttCallback to set the global ACK
* packet identifier to the expected ACK packet identifier.
*
* @param[in] pMqttContext MQTT context pointer.
* @param[in] usPacketIdentifier Packet identifier for expected ACK packet.
* @param[in] ulTimeout Maximum duration to wait for expected ACK packet.
*
* @return EXIT_SUCCESS if the expected ACK packet was received, EXIT_FAILURE
* otherwise.
*/
static int waitForPacketAck( MQTTContext_t * pMqttContext,
uint16_t usPacketIdentifier,
uint32_t ulTimeout );
/**
* @brief Call #MQTT_ProcessLoop in a loop for the duration of a timeout or
* #MQTT_ProcessLoop returns a failure.
*
* @param[in] pMqttContext MQTT context pointer.
* @param[in] ulTimeoutMs Duration to call #MQTT_ProcessLoop for.
*
* @return Returns the return value of the last call to #MQTT_ProcessLoop.
*/
static MQTTStatus_t processLoopWithTimeout( MQTTContext_t * pMqttContext,
uint32_t ulTimeoutMs );
/*-----------------------------------------------------------*/
static uint32_t generateRandomNumber()
{
return( rand() );
}
/*-----------------------------------------------------------*/
static int connectToServerWithBackoffRetries( NetworkContext_t * pNetworkContext )
{
int returnStatus = EXIT_SUCCESS;
BackoffAlgorithmStatus_t backoffAlgStatus = BackoffAlgorithmSuccess;
OpensslStatus_t opensslStatus = OPENSSL_SUCCESS;
BackoffAlgorithmContext_t reconnectParams;
ServerInfo_t serverInfo;
OpensslCredentials_t opensslCredentials;
uint16_t nextRetryBackOff = 0U;
struct timespec tp;
/* Set the pParams member of the network context with desired transport. */
pNetworkContext->pParams = &opensslParams;
/* Initialize information to connect to the MQTT broker. */
serverInfo.pHostName = AWS_IOT_ENDPOINT;
serverInfo.hostNameLength = AWS_IOT_ENDPOINT_LENGTH;
serverInfo.port = AWS_MQTT_PORT;
/* Initialize credentials for establishing TLS session. */
( void ) memset( &opensslCredentials, 0, sizeof( OpensslCredentials_t ) );
opensslCredentials.pRootCaPath = ROOT_CA_CERT_PATH;
opensslCredentials.pClientCertPath = CLIENT_CERT_PATH;
opensslCredentials.pPrivateKeyPath = CLIENT_PRIVATE_KEY_PATH;
opensslCredentials.sniHostName = AWS_IOT_ENDPOINT;
if( AWS_MQTT_PORT == 443 )
{
/* Pass the ALPN protocol name depending on the port being used.
* Please see more details about the ALPN protocol for AWS IoT MQTT endpoint
* in the link below.
* https://aws.amazon.com/blogs/iot/mqtt-with-tls-client-authentication-on-port-443-why-it-is-useful-and-how-it-works/
*/
opensslCredentials.pAlpnProtos = AWS_IOT_ALPN_MQTT_CA_AUTH_OPENSSL;
opensslCredentials.alpnProtosLen = AWS_IOT_ALPN_MQTT_CA_AUTH_OPENSSL_LEN;
}
/* Seed pseudo random number generator used in the demo for
* backoff period calculation when retrying failed network operations
* with broker. */
/* Get current time to seed pseudo random number generator. */
( void ) clock_gettime( CLOCK_REALTIME, &tp );
/* Seed pseudo random number generator with nanoseconds. */
srand( tp.tv_nsec );
/* Initialize reconnect attempts and interval */
BackoffAlgorithm_InitializeParams( &reconnectParams,
CONNECTION_RETRY_BACKOFF_BASE_MS,
CONNECTION_RETRY_MAX_BACKOFF_DELAY_MS,
CONNECTION_RETRY_MAX_ATTEMPTS );
/* Attempt to connect to MQTT broker. If connection fails, retry after
* a timeout. Timeout value will exponentially increase until maximum
* attempts are reached.
*/
do
{
/* Establish a TLS session with the MQTT broker. This example connects
* to the MQTT broker as specified in AWS_IOT_ENDPOINT and AWS_MQTT_PORT
* at the demo config header. */
LogInfo( ( "Establishing a TLS session to %.*s:%d.",
AWS_IOT_ENDPOINT_LENGTH,
AWS_IOT_ENDPOINT,
AWS_MQTT_PORT ) );
opensslStatus = Openssl_Connect( pNetworkContext,
&serverInfo,
&opensslCredentials,
TRANSPORT_SEND_RECV_TIMEOUT_MS,
TRANSPORT_SEND_RECV_TIMEOUT_MS );
if( opensslStatus != OPENSSL_SUCCESS )
{
/* Generate a random number and get back-off value (in milliseconds) for the next connection retry. */
backoffAlgStatus = BackoffAlgorithm_GetNextBackoff( &reconnectParams, generateRandomNumber(), &nextRetryBackOff );
if( backoffAlgStatus == BackoffAlgorithmRetriesExhausted )
{
LogError( ( "Connection to the broker failed, all attempts exhausted." ) );
returnStatus = EXIT_FAILURE;
}
else if( backoffAlgStatus == BackoffAlgorithmSuccess )
{
LogWarn( ( "Connection to the broker failed. Retrying connection "
"after %hu ms backoff.",
( unsigned short ) nextRetryBackOff ) );
Clock_SleepMs( nextRetryBackOff );
}
}
} while( ( opensslStatus != OPENSSL_SUCCESS ) && ( backoffAlgStatus == BackoffAlgorithmSuccess ) );
return returnStatus;
}
/*-----------------------------------------------------------*/
static int getNextFreeIndexForOutgoingPublishes( uint8_t * pIndex )
{
int returnStatus = EXIT_FAILURE;
uint8_t index = 0;
assert( outgoingPublishPackets != NULL );
assert( pIndex != NULL );
for( index = 0; index < MAX_OUTGOING_PUBLISHES; index++ )
{
/* A free index is marked by invalid packet id.
* Check if the the index has a free slot. */
if( outgoingPublishPackets[ index ].packetId == MQTT_PACKET_ID_INVALID )
{
returnStatus = EXIT_SUCCESS;
break;
}
}
/* Copy the available index into the output param. */
*pIndex = index;
return returnStatus;
}
/*-----------------------------------------------------------*/
static void cleanupOutgoingPublishAt( uint8_t index )
{
assert( outgoingPublishPackets != NULL );
assert( index < MAX_OUTGOING_PUBLISHES );
/* Clear the outgoing publish packet. */
( void ) memset( &( outgoingPublishPackets[ index ] ),
0x00,
sizeof( outgoingPublishPackets[ index ] ) );
}
/*-----------------------------------------------------------*/
static void cleanupOutgoingPublishes( void )
{
assert( outgoingPublishPackets != NULL );
/* Clean up all the outgoing publish packets. */
( void ) memset( outgoingPublishPackets, 0x00, sizeof( outgoingPublishPackets ) );
}
/*-----------------------------------------------------------*/
static void cleanupOutgoingPublishWithPacketID( uint16_t packetId )
{
uint8_t index = 0;
assert( outgoingPublishPackets != NULL );
assert( packetId != MQTT_PACKET_ID_INVALID );
/* Clean up all the saved outgoing publishes. */
for( ; index < MAX_OUTGOING_PUBLISHES; index++ )
{
if( outgoingPublishPackets[ index ].packetId == packetId )
{
cleanupOutgoingPublishAt( index );
LogInfo( ( "Cleaned up outgoing publish packet with packet id %u.",
packetId ) );
break;
}
}
}
/*-----------------------------------------------------------*/
static int waitForPacketAck( MQTTContext_t * pMqttContext,
uint16_t usPacketIdentifier,
uint32_t ulTimeout )
{
uint32_t ulMqttProcessLoopEntryTime;
uint32_t ulMqttProcessLoopTimeoutTime;
uint32_t ulCurrentTime;
MQTTStatus_t eMqttStatus = MQTTSuccess;
int returnStatus = EXIT_FAILURE;
/* Reset the ACK packet identifier being received. */
globalAckPacketIdentifier = 0U;
ulCurrentTime = pMqttContext->getTime();
ulMqttProcessLoopEntryTime = ulCurrentTime;
ulMqttProcessLoopTimeoutTime = ulCurrentTime + ulTimeout;
/* Call MQTT_ProcessLoop multiple times until the expected packet ACK
* is received, a timeout happens, or MQTT_ProcessLoop fails. */
while( ( globalAckPacketIdentifier != usPacketIdentifier ) &&
( ulCurrentTime < ulMqttProcessLoopTimeoutTime ) &&
( eMqttStatus == MQTTSuccess || eMqttStatus == MQTTNeedMoreBytes ) )
{
/* Event callback will set #globalAckPacketIdentifier when receiving
* appropriate packet. */
eMqttStatus = MQTT_ProcessLoop( pMqttContext );
ulCurrentTime = pMqttContext->getTime();
}
if( ( ( eMqttStatus != MQTTSuccess ) && ( eMqttStatus != MQTTNeedMoreBytes ) ) ||
( globalAckPacketIdentifier != usPacketIdentifier ) )
{
LogError( ( "MQTT_ProcessLoop failed to receive ACK packet: Expected ACK Packet ID=%02X, LoopDuration=%u, Status=%s",
usPacketIdentifier,
( ulCurrentTime - ulMqttProcessLoopEntryTime ),
MQTT_Status_strerror( eMqttStatus ) ) );
}
else
{
returnStatus = EXIT_SUCCESS;
}
return returnStatus;
}
/*-----------------------------------------------------------*/
static MQTTStatus_t processLoopWithTimeout( MQTTContext_t * pMqttContext,
uint32_t ulTimeoutMs )
{
uint32_t ulMqttProcessLoopTimeoutTime;
uint32_t ulCurrentTime;
MQTTStatus_t eMqttStatus = MQTTSuccess;
ulCurrentTime = pMqttContext->getTime();
ulMqttProcessLoopTimeoutTime = ulCurrentTime + ulTimeoutMs;
/* Call MQTT_ProcessLoop multiple times a timeout happens, or
* MQTT_ProcessLoop fails. */
while( ( ulCurrentTime < ulMqttProcessLoopTimeoutTime ) &&
( eMqttStatus == MQTTSuccess || eMqttStatus == MQTTNeedMoreBytes ) )
{
eMqttStatus = MQTT_ProcessLoop( pMqttContext );
ulCurrentTime = pMqttContext->getTime();
}
return eMqttStatus;
}
/*-----------------------------------------------------------*/
void HandleOtherIncomingPacket( MQTTPacketInfo_t * pPacketInfo,
uint16_t packetIdentifier )
{
/* Handle other packets. */
switch( pPacketInfo->type )
{
case MQTT_PACKET_TYPE_SUBACK:
LogInfo( ( "MQTT_PACKET_TYPE_SUBACK." ) );
/* Make sure ACK packet identifier matches with Request packet identifier. */
assert( globalSubscribePacketIdentifier == packetIdentifier );
/* Update the global ACK packet identifier. */
globalAckPacketIdentifier = packetIdentifier;
break;
case MQTT_PACKET_TYPE_UNSUBACK:
LogInfo( ( "MQTT_PACKET_TYPE_UNSUBACK." ) );
/* Make sure ACK packet identifier matches with Request packet identifier. */
assert( globalUnsubscribePacketIdentifier == packetIdentifier );
/* Update the global ACK packet identifier. */
globalAckPacketIdentifier = packetIdentifier;
break;
case MQTT_PACKET_TYPE_PINGRESP:
/* Nothing to be done from application as library handles
* PINGRESP. */
LogWarn( ( "PINGRESP should not be handled by the application "
"callback when using MQTT_ProcessLoop." ) );
break;
case MQTT_PACKET_TYPE_PUBACK:
LogInfo( ( "PUBACK received for packet id %u.",
packetIdentifier ) );
/* Cleanup publish packet when a PUBACK is received. */
cleanupOutgoingPublishWithPacketID( packetIdentifier );
/* Update the global ACK packet identifier. */
globalAckPacketIdentifier = packetIdentifier;
break;
/* Any other packet type is invalid. */
default:
LogError( ( "Unknown packet type received:(%02x).",
pPacketInfo->type ) );
}
}
/*-----------------------------------------------------------*/
static int handlePublishResend( MQTTContext_t * pMqttContext )
{
int returnStatus = EXIT_SUCCESS;
MQTTStatus_t mqttStatus = MQTTSuccess;
uint8_t index = 0U;
assert( outgoingPublishPackets != NULL );
/* Resend all the QoS1 publishes still in the array. These are the
* publishes that hasn't received a PUBACK. When a PUBACK is
* received, the publish is removed from the array. */
for( index = 0U; index < MAX_OUTGOING_PUBLISHES; index++ )
{
if( outgoingPublishPackets[ index ].packetId != MQTT_PACKET_ID_INVALID )
{
outgoingPublishPackets[ index ].pubInfo.dup = true;
LogInfo( ( "Sending duplicate PUBLISH with packet id %u.",
outgoingPublishPackets[ index ].packetId ) );
mqttStatus = MQTT_Publish( pMqttContext,
&outgoingPublishPackets[ index ].pubInfo,
outgoingPublishPackets[ index ].packetId );
if( mqttStatus != MQTTSuccess )
{
LogError( ( "Sending duplicate PUBLISH for packet id %u "
" failed with status %u.",
outgoingPublishPackets[ index ].packetId,
mqttStatus ) );
returnStatus = EXIT_FAILURE;
break;
}
else
{
LogInfo( ( "Sent duplicate PUBLISH successfully for packet id %u.",
outgoingPublishPackets[ index ].packetId ) );
}
}
}
return returnStatus;
}
/*-----------------------------------------------------------*/
int EstablishMqttSession( MQTTEventCallback_t eventCallback )
{
int returnStatus = EXIT_SUCCESS;
MQTTStatus_t mqttStatus;
MQTTConnectInfo_t connectInfo;
MQTTFixedBuffer_t networkBuffer;
TransportInterface_t transport = { NULL };
bool createCleanSession = false;
MQTTContext_t * pMqttContext = &mqttContext;
NetworkContext_t * pNetworkContext = &networkContext;
bool sessionPresent = false;
assert( pMqttContext != NULL );
assert( pNetworkContext != NULL );
/* Initialize the mqtt context and network context. */
( void ) memset( pMqttContext, 0U, sizeof( MQTTContext_t ) );
( void ) memset( pNetworkContext, 0U, sizeof( NetworkContext_t ) );
returnStatus = connectToServerWithBackoffRetries( pNetworkContext );
if( returnStatus != EXIT_SUCCESS )
{
/* Log error to indicate connection failure after all
* reconnect attempts are over. */
LogError( ( "Failed to connect to MQTT broker %.*s.",
AWS_IOT_ENDPOINT_LENGTH,
AWS_IOT_ENDPOINT ) );
}
else
{
/* Fill in TransportInterface send and receive function pointers.
* For this demo, TCP sockets are used to send and receive data
* from network. Network context is SSL context for OpenSSL.*/
transport.pNetworkContext = pNetworkContext;
transport.send = Openssl_Send;
transport.recv = Openssl_Recv;
/* Fill the values for network buffer. */
networkBuffer.pBuffer = buffer;
networkBuffer.size = NETWORK_BUFFER_SIZE;
/* Initialize MQTT library. */
mqttStatus = MQTT_Init( pMqttContext,
&transport,
Clock_GetTimeMs,
eventCallback,
&networkBuffer );
if( mqttStatus != MQTTSuccess )
{
returnStatus = EXIT_FAILURE;
LogError( ( "MQTT_Init failed: Status = %s.", MQTT_Status_strerror( mqttStatus ) ) );
}
else
{
mqttStatus = MQTT_InitStatefulQoS( pMqttContext,
pOutgoingPublishRecords,
OUTGOING_PUBLISH_RECORD_LEN,
pIncomingPublishRecords,
INCOMING_PUBLISH_RECORD_LEN );
if( mqttStatus != MQTTSuccess )
{
returnStatus = EXIT_FAILURE;
LogError( ( "MQTT_InitStatefulQoS failed: Status = %s.", MQTT_Status_strerror( mqttStatus ) ) );
}
else
{
/* Establish MQTT session by sending a CONNECT packet. */
/* If #createCleanSession is true, start with a clean session
* i.e. direct the MQTT broker to discard any previous session data.
* If #createCleanSession is false, directs the broker to attempt to
* reestablish a session which was already present. */
connectInfo.cleanSession = createCleanSession;
/* The client identifier is used to uniquely identify this MQTT client to
* the MQTT broker. In a production device the identifier can be something
* unique, such as a device serial number. */
connectInfo.pClientIdentifier = CLIENT_IDENTIFIER;
connectInfo.clientIdentifierLength = CLIENT_IDENTIFIER_LENGTH;
/* The maximum time interval in seconds which is allowed to elapse
* between two Control Packets.
* It is the responsibility of the Client to ensure that the interval between
* Control Packets being sent does not exceed the this Keep Alive value. In the
* absence of sending any other Control Packets, the Client MUST send a
* PINGREQ Packet. */
connectInfo.keepAliveSeconds = MQTT_KEEP_ALIVE_INTERVAL_SECONDS;
/* Username and password for authentication. Not used in this demo. */
connectInfo.pUserName = METRICS_STRING;
connectInfo.userNameLength = METRICS_STRING_LENGTH;
connectInfo.pPassword = NULL;
connectInfo.passwordLength = 0U;
/* Send MQTT CONNECT packet to broker. */
mqttStatus = MQTT_Connect( pMqttContext,
&connectInfo,
NULL,
CONNACK_RECV_TIMEOUT_MS,
&sessionPresent );
if( mqttStatus != MQTTSuccess )
{
returnStatus = EXIT_FAILURE;
LogError( ( "Connection with MQTT broker failed with status %u.", mqttStatus ) );
}
else
{
LogInfo( ( "MQTT connection successfully established with broker." ) );
}
}
if( returnStatus == EXIT_SUCCESS )
{
/* Keep a flag for indicating if MQTT session is established. This
* flag will mark that an MQTT DISCONNECT has to be sent at the end
* of the demo even if there are intermediate failures. */
mqttSessionEstablished = true;
}
if( returnStatus == EXIT_SUCCESS )
{
/* Check if session is present and if there are any outgoing publishes
* that need to resend. This is only valid if the broker is
* re-establishing a session which was already present. */
if( sessionPresent == true )
{
LogInfo( ( "An MQTT session with broker is re-established. "
"Resending unacked publishes." ) );
/* Handle all the resend of publish messages. */
returnStatus = handlePublishResend( &mqttContext );
}
else
{
LogInfo( ( "A clean MQTT connection is established."
" Cleaning up all the stored outgoing publishes." ) );
/* Clean up the outgoing publishes waiting for ack as this new
* connection doesn't re-establish an existing session. */
cleanupOutgoingPublishes();
}
}
}
}
return returnStatus;
}
/*-----------------------------------------------------------*/
int32_t DisconnectMqttSession( void )
{
MQTTStatus_t mqttStatus = MQTTSuccess;
int returnStatus = EXIT_SUCCESS;
MQTTContext_t * pMqttContext = &mqttContext;
NetworkContext_t * pNetworkContext = &networkContext;
assert( pMqttContext != NULL );
assert( pNetworkContext != NULL );
if( mqttSessionEstablished == true )
{
/* Send DISCONNECT. */
mqttStatus = MQTT_Disconnect( pMqttContext );
if( mqttStatus != MQTTSuccess )
{
LogError( ( "Sending MQTT DISCONNECT failed with status=%u.",
mqttStatus ) );
returnStatus = EXIT_FAILURE;
}
}
/* End TLS session, then close TCP connection. */
( void ) Openssl_Disconnect( pNetworkContext );
return returnStatus;
}
/*-----------------------------------------------------------*/
int32_t SubscribeToTopic( const char * pTopicFilter,
uint16_t topicFilterLength )
{
int returnStatus = EXIT_SUCCESS;
MQTTStatus_t mqttStatus;
MQTTContext_t * pMqttContext = &mqttContext;
MQTTSubscribeInfo_t pSubscriptionList[ 1 ];
assert( pMqttContext != NULL );
assert( pTopicFilter != NULL );
assert( topicFilterLength > 0 );
/* Start with everything at 0. */
( void ) memset( ( void * ) pSubscriptionList, 0x00, sizeof( pSubscriptionList ) );
/* This example subscribes to only one topic and uses QOS1. */
pSubscriptionList[ 0 ].qos = MQTTQoS1;
pSubscriptionList[ 0 ].pTopicFilter = pTopicFilter;
pSubscriptionList[ 0 ].topicFilterLength = topicFilterLength;
/* Generate packet identifier for the SUBSCRIBE packet. */
globalSubscribePacketIdentifier = MQTT_GetPacketId( pMqttContext );
/* Send SUBSCRIBE packet. */
mqttStatus = MQTT_Subscribe( pMqttContext,
pSubscriptionList,
sizeof( pSubscriptionList ) / sizeof( MQTTSubscribeInfo_t ),
globalSubscribePacketIdentifier );
if( mqttStatus != MQTTSuccess )
{
LogError( ( "Failed to send SUBSCRIBE packet to broker with error = %u.",
mqttStatus ) );
returnStatus = EXIT_FAILURE;
}
else
{
LogInfo( ( "SUBSCRIBE topic %.*s to broker.",
topicFilterLength,
pTopicFilter ) );
/* Process incoming packet from the broker. Acknowledgment for subscription
* ( SUBACK ) will be received here. However after sending the subscribe, the
* client may receive a publish before it receives a subscribe ack. Since this
* demo is subscribing to the topic to which no one is publishing, probability
* of receiving publish message before subscribe ack is zero; but application
* must be ready to receive any packet. This demo uses MQTT_ProcessLoop to
* receive packet from network. */
returnStatus = waitForPacketAck( pMqttContext,
globalSubscribePacketIdentifier,
MQTT_PROCESS_LOOP_TIMEOUT_MS );
}
return returnStatus;
}
/*-----------------------------------------------------------*/
int32_t UnsubscribeFromTopic( const char * pTopicFilter,
uint16_t topicFilterLength )
{
int returnStatus = EXIT_SUCCESS;
MQTTStatus_t mqttStatus;
MQTTContext_t * pMqttContext = &mqttContext;
MQTTSubscribeInfo_t pSubscriptionList[ 1 ];
assert( pMqttContext != NULL );
assert( pTopicFilter != NULL );
assert( topicFilterLength > 0 );
/* Start with everything at 0. */
( void ) memset( ( void * ) pSubscriptionList, 0x00, sizeof( pSubscriptionList ) );
/* This example subscribes to only one topic and uses QOS1. */
pSubscriptionList[ 0 ].qos = MQTTQoS1;
pSubscriptionList[ 0 ].pTopicFilter = pTopicFilter;
pSubscriptionList[ 0 ].topicFilterLength = topicFilterLength;
/* Generate packet identifier for the UNSUBSCRIBE packet. */
globalUnsubscribePacketIdentifier = MQTT_GetPacketId( pMqttContext );
/* Send UNSUBSCRIBE packet. */
mqttStatus = MQTT_Unsubscribe( pMqttContext,
pSubscriptionList,
sizeof( pSubscriptionList ) / sizeof( MQTTSubscribeInfo_t ),
globalUnsubscribePacketIdentifier );
if( mqttStatus != MQTTSuccess )
{
LogError( ( "Failed to send UNSUBSCRIBE packet to broker with error = %u.",
mqttStatus ) );
returnStatus = EXIT_FAILURE;
}
else
{
LogInfo( ( "UNSUBSCRIBE sent topic %.*s to broker.",
topicFilterLength,
pTopicFilter ) );
/* Process incoming packet from the broker. Acknowledgment for subscription
* ( SUBACK ) will be received here. However after sending the subscribe, the
* client may receive a publish before it receives a subscribe ack. Since this
* demo is subscribing to the topic to which no one is publishing, probability