File content as of revision 3:40f482ed0be8:

// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

#include <stdlib.h>
#ifdef _CRTDBG_MAP_ALLOC
#include <crtdbg.h>
#endif
#include "azure_c_shared_utility/gballoc.h"

#include "azure_c_shared_utility/iot_logging.h"
#include "azure_c_shared_utility/strings.h"
#include "azure_c_shared_utility/doublylinkedlist.h"
#include "azure_c_shared_utility/crt_abstractions.h"

#include "iothub_client_ll.h"
#include "iothub_client_private.h"
#include "iothubtransportmqtt.h"
#include "azure_umqtt_c/mqtt_client.h"
#include "azure_c_shared_utility/sastoken.h"
#include "azure_c_shared_utility/tickcounter.h"

#include "azure_c_shared_utility/tlsio.h"
#include "azure_c_shared_utility/platform.h"

#include "azure_c_shared_utility/string_tokenizer.h"
#include "iothub_client_version.h"

#include <stdarg.h>
#include <stdio.h>

#define SAS_TOKEN_DEFAULT_LIFETIME  3600
#define SAS_REFRESH_MULTIPLIER      .8
#define EPOCH_TIME_T_VALUE          0
#define DEFAULT_MQTT_KEEPALIVE      4*60 // 4 min
#define DEFAULT_PORT_NUMBER         8883
#define DEFAULT_TEMP_STRING_LEN     256
#define BUILD_CONFIG_USERNAME       24
#define EVENT_TOPIC_DEFAULT_LEN     27
#define SAS_TOKEN_DEFAULT_LEN       10
#define RESEND_TIMEOUT_VALUE_MIN    1*60
#define MAX_SEND_RECOUNT_LIMIT      2
#define DEFAULT_CONNECTION_INTERVAL 30
#define FAILED_CONN_BACKOFF_VALUE   5

static const char* DEVICE_MSG_TOPIC = "devices/%s/messages/devicebound/#";
static const char* DEVICE_DEVICE_TOPIC = "devices/%s/messages/events/";
static const char* PROPERTY_SEPARATOR = "&";

typedef struct SYSTEM_PROPERTY_INFO_TAG
{
	const char* propName;
	size_t propLength;
} SYSTEM_PROPERTY_INFO;

static SYSTEM_PROPERTY_INFO sysPropList[] = {
	{ "%24.exp", 7 },
	{ "%24.mid", 7 },
	{ "%24.uid", 7 },
	{ "%24.to", 6 },
	{ "%24.cid", 7 },
	{ "devices/", 8 },
	{ "iothub-operation", 16 },
	{ "iothub-ack", 10 }
};

TICK_COUNTER_HANDLE g_msgTickCounter;

typedef struct MQTTTRANSPORT_HANDLE_DATA_TAG
{
	STRING_HANDLE device_id;
	STRING_HANDLE device_key;
	STRING_HANDLE sasTokenSr;
	STRING_HANDLE mqttEventTopic;
	STRING_HANDLE mqttMessageTopic;
	STRING_HANDLE hostAddress;
	// The current mqtt iothub implementation requires that the hub name and the domain suffix be passed as the first of a series of segments
	// passed through the username portion of the connection frame.
	// The second segment will contain the device id.  The two segments are delemited by a "/".
	// The first segment can be a maximum 256 characters.
	// The second segment can be a maximum 128 characters.
	// With the / delimeter you have 384 chars (Plus a terminator of 0).
	STRING_HANDLE configPassedThroughUsername;
	int portNum;
	MQTT_CLIENT_HANDLE mqttClient;
	uint16_t packetId;
	bool sasTokenFromUser;
	bool isRegistered;
	bool connected;
	bool subscribed;
	bool receiveMessages;
	bool destroyCalled;
	DLIST_ENTRY waitingForAck;
	PDLIST_ENTRY waitingToSend;
	IOTHUB_CLIENT_LL_HANDLE llClientHandle;
	CONTROL_PACKET_TYPE currPacketState;
	XIO_HANDLE xioTransport;
	int keepAliveValue;
	uint64_t mqtt_connect_time;
	size_t connectFailCount;
	uint64_t connectTick;
} MQTTTRANSPORT_HANDLE_DATA, *PMQTTTRANSPORT_HANDLE_DATA;

typedef struct MQTT_MESSAGE_DETAILS_LIST_TAG
{
	uint64_t msgPublishTime;
	size_t retryCount;
	IOTHUB_MESSAGE_LIST* iotHubMessageEntry;
	void* context;
	uint16_t msgPacketId;
	DLIST_ENTRY entry;
} MQTT_MESSAGE_DETAILS_LIST, *PMQTT_MESSAGE_DETAILS_LIST;

static void defaultPrintLogFunction(unsigned int options, char* format, ...)
{
	va_list args;
	va_start(args, format);
	(void)vprintf(format, args);
	va_end(args);

	if (options & LOG_LINE)
	{
		(void)printf("\r\n");
	}
}

static void sendMsgComplete(IOTHUB_MESSAGE_LIST* iothubMsgList, PMQTTTRANSPORT_HANDLE_DATA transportState, IOTHUB_BATCHSTATE_RESULT batchResult)
{
	DLIST_ENTRY messageCompleted;
	DList_InitializeListHead(&messageCompleted);
	DList_InsertTailList(&messageCompleted, &(iothubMsgList->entry));
	IoTHubClient_LL_SendComplete(transportState->llClientHandle, &messageCompleted, batchResult);
}

static STRING_HANDLE addPropertiesTouMqttMessage(IOTHUB_MESSAGE_HANDLE iothub_message_handle, const char* eventTopic)
{
	STRING_HANDLE result = STRING_construct(eventTopic);
	const char* const* propertyKeys;
	const char* const* propertyValues;
	size_t propertyCount;

	// Construct Properties
	MAP_HANDLE properties_map = IoTHubMessage_Properties(iothub_message_handle);
	if (properties_map != NULL)
	{
		if (Map_GetInternals(properties_map, &propertyKeys, &propertyValues, &propertyCount) != MAP_OK)
		{
			LogError("Failed to get the internals of the property map.");
			STRING_delete(result);
			result = NULL;
		}
		else
		{
			if (propertyCount != 0)
			{
				for (size_t index = 0; index < propertyCount && result != NULL; index++)
				{
					size_t len = strlen(propertyKeys[index]) + strlen(propertyValues[index]) + 2;
					char* propValues = malloc(len+1);
					if (propValues == NULL)
					{
						STRING_delete(result);
						result = NULL;
					}
					else
					{
						sprintf(propValues, "%s=%s%s", propertyKeys[index], propertyValues[index], propertyCount - 1 == index ? "" : "&");
						if (STRING_concat(result, propValues) != 0)
						{
							STRING_delete(result);
							result = NULL;
						}
						free(propValues);
					}
				}
			}
		}
	}
	return result;
}

static int publishMqttMessage(PMQTTTRANSPORT_HANDLE_DATA transportState, MQTT_MESSAGE_DETAILS_LIST* mqttMsgEntry, const unsigned char* payload, size_t len)
{
	int result;
	STRING_HANDLE msgTopic = addPropertiesTouMqttMessage(mqttMsgEntry->iotHubMessageEntry->messageHandle, STRING_c_str(transportState->mqttEventTopic));
	if (msgTopic == NULL)
	{
		result = __LINE__;
	}
	else
	{
		MQTT_MESSAGE_HANDLE mqttMsg = mqttmessage_create(transportState->packetId++, STRING_c_str(msgTopic), DELIVER_AT_LEAST_ONCE, payload, len);
		if (mqttMsg == NULL)
		{
			result = __LINE__;
		}
		else
		{
			if (mqtt_client_publish(transportState->mqttClient, mqttMsg) != 0)
			{
				result = __LINE__;
			}
			else
			{
				mqttMsgEntry->retryCount++;
				(void)tickcounter_get_current_ms(g_msgTickCounter, &mqttMsgEntry->msgPublishTime);
				result = 0;
			}
			mqttmessage_destroy(mqttMsg);
		}
		STRING_delete(msgTopic);
	}
	return result;
}

static bool isSystemProperty(const char* tokenData)
{
	bool result = false;
	size_t propCount = sizeof(sysPropList)/sizeof(sysPropList[0]);
	for (size_t index = 0; index < propCount; index++)
	{
		if (memcmp(tokenData, sysPropList[index].propName, sysPropList[index].propLength) == 0)
		{
			result = true;
			break;
		}
	}
	return result;
}

static int extractMqttProperties(IOTHUB_MESSAGE_HANDLE IoTHubMessage, MQTT_MESSAGE_HANDLE msgHandle)
{
	int result;
	STRING_HANDLE mqttTopic = STRING_construct(mqttmessage_getTopicName(msgHandle));

	STRING_TOKENIZER_HANDLE token = STRING_TOKENIZER_create(mqttTopic);
	if (token != NULL)
	{
		MAP_HANDLE propertyMap = IoTHubMessage_Properties(IoTHubMessage);
		if (propertyMap == NULL)
		{
			LogError("Failure to retrieve IoTHubMessage_properties.");
			result = __LINE__;
		}
		else
		{
			STRING_HANDLE output = STRING_new();
			if (output == NULL)
			{
				LogError("Failure to allocate STRING_new.");
				result = __LINE__;
			}
			else
			{
				result = 0;
				while (STRING_TOKENIZER_get_next_token(token, output, PROPERTY_SEPARATOR) == 0 && result == 0)
				{
					const char* tokenData = STRING_c_str(output);
					size_t tokenLen = strlen(tokenData);
					if (tokenData == NULL || tokenLen == 0)
					{
						break;
					}
					else
					{
						if (!isSystemProperty(tokenData) )
						{
							const char* iterator = tokenData;
							while (iterator != NULL && *iterator != '\0' && result == 0)
							{
								if (*iterator == '=')
								{
									size_t nameLen = iterator - tokenData;
									char* propName = malloc(nameLen + 1);

									size_t valLen = tokenLen - (nameLen + 1) + 1;
									char* propValue = malloc(valLen + 1);

									if (propName == NULL || propValue == NULL)
									{
										result = __LINE__;
									}
									else
									{
										strncpy(propName, tokenData, nameLen);
										propName[nameLen] = '\0';

										strncpy(propValue, iterator + 1, valLen);
										propValue[valLen] = '\0';

										if (Map_AddOrUpdate(propertyMap, propName, propValue) != MAP_OK)
										{
											LogError("Map_AddOrUpdate failed.");
											result = __LINE__;
										}
									}
									free(propName);
									free(propValue);

									break;
								}
								iterator++;
							}
						}
					}
				}
				STRING_delete(output);
			}
		}
		STRING_TOKENIZER_destroy(token);
	}
	else
	{
		LogError("Unable to create Tokenizer object.");
		result = __LINE__;
	}
	STRING_delete(mqttTopic);

	return result;
}

static void MqttRecvCallback(MQTT_MESSAGE_HANDLE msgHandle, void* callbackCtx)
{
	if (msgHandle != NULL && callbackCtx != NULL)
	{
		const APP_PAYLOAD* appPayload = mqttmessage_getApplicationMsg(msgHandle);
		IOTHUB_MESSAGE_HANDLE IoTHubMessage = IoTHubMessage_CreateFromByteArray(appPayload->message, appPayload->length);
		if (IoTHubMessage == NULL)
		{
			LogError("IotHub Message creation has failed.");
		}
		else
		{
			// Will need to update this when the service has messages that can be rejected
			(void)extractMqttProperties(IoTHubMessage, msgHandle);
			PMQTTTRANSPORT_HANDLE_DATA transportData = (PMQTTTRANSPORT_HANDLE_DATA)callbackCtx;
			if (IoTHubClient_LL_MessageCallback(transportData->llClientHandle, IoTHubMessage) != IOTHUBMESSAGE_ACCEPTED)
			{
				LogError("Event not accepted by our client.");
			}
			IoTHubMessage_Destroy(IoTHubMessage);
		}
	}
}

static void MqttOpCompleteCallback(MQTT_CLIENT_HANDLE handle, MQTT_CLIENT_EVENT_RESULT actionResult, const void* msgInfo, void* callbackCtx)
{
	(void)handle;
	if (callbackCtx != NULL)
	{
		PMQTTTRANSPORT_HANDLE_DATA transportData = (PMQTTTRANSPORT_HANDLE_DATA)callbackCtx;

		switch (actionResult)
		{
		case MQTT_CLIENT_ON_PUBLISH_ACK:
		case MQTT_CLIENT_ON_PUBLISH_COMP:
		{
			const PUBLISH_ACK* puback = (const PUBLISH_ACK*)msgInfo;
			if (puback != NULL)
			{
				PDLIST_ENTRY currentListEntry = transportData->waitingForAck.Flink;
				while (currentListEntry != &transportData->waitingForAck)
				{
					MQTT_MESSAGE_DETAILS_LIST* mqttMsgEntry = containingRecord(currentListEntry, MQTT_MESSAGE_DETAILS_LIST, entry);
					DLIST_ENTRY saveListEntry;
					saveListEntry.Flink = currentListEntry->Flink;

					if (puback->packetId == mqttMsgEntry->msgPacketId)
					{
						(void)DList_RemoveEntryList(currentListEntry); //First remove the item from Waiting for Ack List.
						sendMsgComplete(mqttMsgEntry->iotHubMessageEntry, transportData, IOTHUB_BATCHSTATE_SUCCESS);
						free(mqttMsgEntry);
					}
					currentListEntry = saveListEntry.Flink;
				}
			}
			break;
		}
		case MQTT_CLIENT_ON_CONNACK:
		{
			const CONNECT_ACK* connack = (const CONNECT_ACK*)msgInfo;
			if (connack != NULL)
			{
				if (connack->returnCode == CONNECTION_ACCEPTED)
				{
					// The connect packet has been acked
					transportData->currPacketState = CONNACK_TYPE;
				}
				else
				{
					LogError("Connection not accepted, return code: %d.", connack->returnCode);
					(void)mqtt_client_disconnect(transportData->mqttClient);
					transportData->connected = false;
					transportData->currPacketState = PACKET_TYPE_ERROR;
				}
			}
			else
			{
				LogError("MQTT_CLIENT_ON_CONNACK CONNACK parameter is NULL.");
			}
			break;
		}
		case MQTT_CLIENT_ON_SUBSCRIBE_ACK:
		{
			const SUBSCRIBE_ACK* suback = (const SUBSCRIBE_ACK*)msgInfo;
			if (suback != NULL)
			{
				if (suback->qosCount == 1)
				{
					// The connect packet has been acked
					transportData->currPacketState = SUBACK_TYPE;
				}
				else
				{
					LogError("QOS count was not expected: %d.", (int)suback->qosCount);
				}
			}
			break;
		}
		case MQTT_CLIENT_ON_PUBLISH_RECV:
		case MQTT_CLIENT_ON_PUBLISH_REL:
		{
			// Currently not used
			break;
		}
		case MQTT_CLIENT_ON_DISCONNECT:
		{
			// Close the client so we can reconnect again
			transportData->connected = false;
			transportData->currPacketState = DISCONNECT_TYPE;
			break;
		}
		case MQTT_CLIENT_ON_ERROR:
		{
			xio_close(transportData->xioTransport, NULL, NULL);
			transportData->connected = false;
			transportData->subscribed = false;
			transportData->currPacketState = PACKET_TYPE_ERROR;
		}
		}
	}
}

const XIO_HANDLE getIoTransportProvider(const char* fqdn, int port)
{
	TLSIO_CONFIG tls_io_config = { fqdn, port };
	const IO_INTERFACE_DESCRIPTION* io_interface_description = platform_get_default_tlsio();
	return (void*)xio_create(io_interface_description, &tls_io_config, NULL/*defaultPrintLogFunction*/);
}

static int SubscribeToMqttProtocol(PMQTTTRANSPORT_HANDLE_DATA transportState)
{
	int result;

	if (transportState->receiveMessages && !transportState->subscribed)
	{
		SUBSCRIBE_PAYLOAD subscribe[] = {
			{ STRING_c_str(transportState->mqttMessageTopic), DELIVER_AT_LEAST_ONCE }
		};
		/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_016: [IoTHubTransportMqtt_Subscribe shall call mqtt_client_subscribe to subscribe to the Message Topic.] */
		if (mqtt_client_subscribe(transportState->mqttClient, transportState->packetId++, subscribe, 1) != 0)
		{
			/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_017: [Upon failure IoTHubTransportMqtt_Subscribe shall return a non-zero value.] */
			result = __LINE__;
		}
		else
		{
			/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_018: [On success IoTHubTransportMqtt_Subscribe shall return 0.] */
			transportState->subscribed = true;
			transportState->currPacketState = SUBSCRIBE_TYPE;
			result = 0;
		}
	}
	else
	{
		if (transportState->receiveMessages)
		{
			transportState->currPacketState = SUBSCRIBE_TYPE;
		}
		else
		{
			transportState->currPacketState = PUBLISH_TYPE;
		}
	}
	return result;
}

static const unsigned char* RetrieveMessagePayload(IOTHUB_MESSAGE_HANDLE messageHandle, size_t* length)
{
	const unsigned char* result;

	IOTHUBMESSAGE_CONTENT_TYPE contentType = IoTHubMessage_GetContentType(messageHandle);
	if (contentType == IOTHUBMESSAGE_BYTEARRAY)
	{
		if (IoTHubMessage_GetByteArray(messageHandle, &result, length) != IOTHUB_MESSAGE_OK)
		{
			LogError("Failure result from IoTHubMessage_GetByteArray");
			result = NULL;
			*length = 0;
		}
	}
	else if (contentType == IOTHUBMESSAGE_STRING)
	{
		result = (const unsigned char*)IoTHubMessage_GetString(messageHandle);
		if (result == NULL)
		{
			LogError("Failure result from IoTHubMessage_GetString");
			result = NULL;
			*length = 0;
		}
		else
		{
			*length = strlen((const char*)result);
		}
	}
	else
	{
		result = NULL;
		*length = 0;
	}
	return result;
}

static STRING_HANDLE ConstructSasToken(const char* iothubName, const char* iotHubSuffix, const char* deviceId)
{
	STRING_HANDLE result;
	size_t len = strlen(iothubName);
	len += strlen(iotHubSuffix);
	len += strlen(deviceId);

	char* sasToken = malloc(len + SAS_TOKEN_DEFAULT_LEN + 1);
	if (sasToken == NULL)
	{
		result = NULL;
	}
	else
	{
		(void)sprintf(sasToken, "%s.%s/devices/%s", iothubName, iotHubSuffix, deviceId);
		result = STRING_construct(sasToken);
		free(sasToken);
	}
	return result;
}

static STRING_HANDLE ConstructEventTopic(const char* deviceId)
{
	STRING_HANDLE result;
	size_t len = strlen(deviceId);

	char* eventTopic = malloc(len + EVENT_TOPIC_DEFAULT_LEN + 1);
	if (eventTopic == NULL)
	{
		result = NULL;
	}
	else
	{
		(void)sprintf(eventTopic, DEVICE_DEVICE_TOPIC, deviceId);
		result = STRING_construct(eventTopic);
		free(eventTopic);
	}
	return result;
}

static STRING_HANDLE ConstructMessageTopic(const char* deviceId)
{
	STRING_HANDLE result;
	size_t len = strlen(deviceId);

	char* messageTopic = malloc(len + 32 + 1);
	if (messageTopic == NULL)
	{
		result = NULL;
	}
	else
	{
		(void)sprintf(messageTopic, DEVICE_MSG_TOPIC, deviceId);
		result = STRING_construct(messageTopic);
		free(messageTopic);
	}
	return result;
}

static int GetTransportProviderIfNecessary(PMQTTTRANSPORT_HANDLE_DATA transportState)
{
	int result;

	if (transportState->xioTransport == NULL)
	{
		// construct address
		const char* hostAddress = STRING_c_str(transportState->hostAddress);
		const char* hostName = strstr(hostAddress, "//");
		if (hostName == NULL)
		{
			hostName = hostAddress;
		}
		else
		{
			// Increment beyond the double backslash
			hostName += 2;
		}
		transportState->xioTransport = getIoTransportProvider(hostName, transportState->portNum);
		if (transportState->xioTransport == NULL)
		{
			LogError("Unable to create the lower level TLS layer.");
			result = __LINE__;
		}
		else
		{
			result = 0;
		}
	}
	else
	{
		result = 0;
	}
	return result;
}

static int SendMqttConnectMsg(PMQTTTRANSPORT_HANDLE_DATA transportState)
{
	int result;

	// Construct SAS token
	size_t secSinceEpoch = (size_t)(difftime(get_time(NULL), EPOCH_TIME_T_VALUE) + 0);
	size_t expiryTime = secSinceEpoch + SAS_TOKEN_DEFAULT_LIFETIME;

	// Not checking the success of this variable, if fail it will fail in the SASToken creation and return false;
	STRING_HANDLE emptyKeyName = STRING_new();
    if (emptyKeyName == NULL)
    {
        result = __LINE__;
    }
    else
    {
        STRING_HANDLE sasToken = NULL;
        if (transportState->sasTokenFromUser)
        {
            sasToken = STRING_clone(transportState->sasTokenSr);
        }
        else
        {
            sasToken = SASToken_Create(transportState->device_key, transportState->sasTokenSr, emptyKeyName, expiryTime);
        }

        if (sasToken == NULL)
        {
            result = __LINE__;
        }
        else
        {
            MQTT_CLIENT_OPTIONS options = { 0 };
            options.clientId = (char*)STRING_c_str(transportState->device_id);
            options.willMessage = NULL;
            options.username = (char*)STRING_c_str(transportState->configPassedThroughUsername);
            options.password = (char*)STRING_c_str(sasToken);
            options.keepAliveInterval = transportState->keepAliveValue;
            options.useCleanSession = false;
            options.qualityOfServiceValue = DELIVER_AT_LEAST_ONCE;

            if (GetTransportProviderIfNecessary(transportState) == 0)
            {
                if (mqtt_client_connect(transportState->mqttClient, transportState->xioTransport, &options) != 0)
                {
                    LogError("failure connecting to address %s:%d.", STRING_c_str(transportState->hostAddress), transportState->portNum);
                    xio_destroy(transportState->xioTransport);
                    transportState->xioTransport = NULL;
                    result = __LINE__;
                }
                else
                {
                    (void)tickcounter_get_current_ms(g_msgTickCounter, &transportState->mqtt_connect_time);
                    result = 0;
                }
            }
            else
            {
                result = __LINE__;
            }
        }
        STRING_delete(emptyKeyName);
        STRING_delete(sasToken);
    }
	return result;
}

static int InitializeConnection(PMQTTTRANSPORT_HANDLE_DATA transportState)
{
	int result = 0;

	// Make sure we're not destroying the object
	if (!transportState->destroyCalled)
	{
		// If we are not connected then check to see if we need 
		// to back off the connecting to the server
		if (!transportState->connected)
		{
			// Default makeConnection as true if something goes wrong we'll make the connection
			bool makeConnection = true;
			// If we've failed for FAILED_CONN_BACKOFF_VALUE straight times them let's slow down connection
			// to the service
			if (transportState->connectFailCount > FAILED_CONN_BACKOFF_VALUE)
			{
				uint64_t currentTick;
				if (tickcounter_get_current_ms(g_msgTickCounter, &currentTick) == 0)
				{
					if ( ((currentTick - transportState->connectTick)/1000) <= DEFAULT_CONNECTION_INTERVAL)
					{
						result = __LINE__;
						makeConnection = false;
					}
				}
			}

			if (makeConnection)
			{
				(void)tickcounter_get_current_ms(g_msgTickCounter, &transportState->connectTick);
				if (SendMqttConnectMsg(transportState) != 0)
				{
					transportState->connectFailCount++;
					result = __LINE__;
				}
				else
				{
					transportState->connectFailCount = 0;
					transportState->connected = true;
					result = 0;
				}
			}
		}

		if (transportState->connected)
		{
			// We are connected and not being closed, so does SAS need to reconnect?
			uint64_t current_time;
			(void)tickcounter_get_current_ms(g_msgTickCounter, &current_time);
			if ((current_time - transportState->mqtt_connect_time) / 1000 > (SAS_TOKEN_DEFAULT_LIFETIME*SAS_REFRESH_MULTIPLIER))
			{
				(void)mqtt_client_disconnect(transportState->mqttClient);
				transportState->subscribed = false;
				transportState->connected = false;
				transportState->currPacketState = UNKNOWN_TYPE;
			}
		}
	}
	return result;
}

static STRING_HANDLE buildConfigForUsername(const IOTHUB_CLIENT_CONFIG* upperConfig)
{
	STRING_HANDLE result;

	size_t len = strlen(upperConfig->iotHubName)+strlen(upperConfig->iotHubSuffix)+strlen(upperConfig->deviceId)+strlen(CLIENT_DEVICE_TYPE_PREFIX)+strlen(IOTHUB_SDK_VERSION);
	char* eventTopic = malloc(len + BUILD_CONFIG_USERNAME + 1);
	if (eventTopic == NULL)
	{
		result = NULL;
	}
	else
	{
		(void)sprintf(eventTopic, "%s.%s/%s/DeviceClientType=%s%%2F%s", upperConfig->iotHubName, upperConfig->iotHubSuffix, upperConfig->deviceId, CLIENT_DEVICE_TYPE_PREFIX, IOTHUB_SDK_VERSION);
		result = STRING_construct(eventTopic);
		free(eventTopic);
	}
	return result;
}

static PMQTTTRANSPORT_HANDLE_DATA InitializeTransportHandleData(const IOTHUB_CLIENT_CONFIG* upperConfig, PDLIST_ENTRY waitingToSend)
{
	PMQTTTRANSPORT_HANDLE_DATA state = (PMQTTTRANSPORT_HANDLE_DATA)malloc(sizeof(MQTTTRANSPORT_HANDLE_DATA));
	if (state == NULL)
	{
		LogError("Could not create MQTT transport state. Memory allocation failed.");
	}
	else if ((state->device_id = STRING_construct(upperConfig->deviceId)) == NULL)
	{
		free(state);
		state = NULL;
	}
    else
    {
        state->device_key = NULL;
        state->sasTokenSr = NULL;

        if ((upperConfig->deviceKey != NULL) && ((state->device_key = STRING_construct(upperConfig->deviceKey)) == NULL))
        {
            LogError("Could not create device key for MQTT");
            STRING_delete(state->device_id);
            free(state);
            state = NULL;
        }
        else if ((upperConfig->deviceSasToken != NULL) && ((state->sasTokenSr = STRING_construct(upperConfig->deviceSasToken)) == NULL))
        {
            LogError("Could not create Sas Token Sr String");
            STRING_delete(state->device_id);
            STRING_delete(state->device_key);
            free(state);
            state = NULL;
        }
        else if ((upperConfig->deviceSasToken == NULL) && ((state->sasTokenSr = ConstructSasToken(upperConfig->iotHubName, upperConfig->iotHubSuffix, upperConfig->deviceId)) == NULL))
        {
            LogError("Could not create Sas Token Sr String.");
            STRING_delete(state->device_id);
            STRING_delete(state->device_key);
            free(state);
            state = NULL;
        }
        else if ((state->mqttEventTopic = ConstructEventTopic(upperConfig->deviceId)) == NULL)
        {
            LogError("Could not create mqttEventTopic for MQTT");
            STRING_delete(state->sasTokenSr);
            STRING_delete(state->device_key);
            STRING_delete(state->device_id);
            free(state);
            state = NULL;
        }
        else if ((state->mqttMessageTopic = ConstructMessageTopic(upperConfig->deviceId)) == NULL)
        {
            LogError("Could not create mqttMessageTopic for MQTT");
            STRING_delete(state->mqttEventTopic);
            STRING_delete(state->sasTokenSr);
            STRING_delete(state->device_key);
            STRING_delete(state->device_id);
            free(state);
            state = NULL;
        }
        else
        {
            state->mqttClient = mqtt_client_init(MqttRecvCallback, MqttOpCompleteCallback, state, defaultPrintLogFunction);
            if (state->mqttClient == NULL)
            {
                STRING_delete(state->mqttEventTopic);
                STRING_delete(state->mqttMessageTopic);
                STRING_delete(state->sasTokenSr);
                STRING_delete(state->device_key);
                STRING_delete(state->device_id);
                free(state);
                state = NULL;
            }
            else
            {
                /* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_008: [The hostname shall be constructed using the iothubname and iothubSuffix.] */
                // TODO: need to strip the ssl or http or tls
                char tempAddress[DEFAULT_TEMP_STRING_LEN];
                (void)snprintf(tempAddress, DEFAULT_TEMP_STRING_LEN, "%s.%s", upperConfig->iotHubName, upperConfig->iotHubSuffix);
                if ((state->hostAddress = STRING_construct(tempAddress)) == NULL)
                {
                    STRING_delete(state->mqttEventTopic);
                    STRING_delete(state->mqttMessageTopic);
                    STRING_delete(state->sasTokenSr);
                    STRING_delete(state->device_key);
                    STRING_delete(state->device_id);
                    free(state);
                    state = NULL;
                }
                else if ((state->configPassedThroughUsername = buildConfigForUsername(upperConfig)) == NULL)
                {
                    STRING_delete(state->hostAddress);
                    STRING_delete(state->mqttEventTopic);
                    STRING_delete(state->mqttMessageTopic);
                    STRING_delete(state->sasTokenSr);
                    STRING_delete(state->device_key);
                    STRING_delete(state->device_id);
                    free(state);
                    state = NULL;
                }
                else
                {
                    /* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_010: [IoTHubTransportMqtt_Create shall allocate memory to save its internal state where all topics, hostname, device_id, device_key, sasTokenSr and client handle shall be saved.] */
                    DList_InitializeListHead(&(state->waitingForAck));
                    state->sasTokenFromUser = (upperConfig->deviceSasToken == NULL) ? false : true;
                    state->destroyCalled = false;
                    state->isRegistered = false;
                    state->subscribed = false;
                    state->connected = false;
                    state->receiveMessages = false;
                    state->packetId = 1;
                    state->llClientHandle = NULL;
                    state->xioTransport = NULL;
                    state->portNum = DEFAULT_PORT_NUMBER;
                    state->waitingToSend = waitingToSend;
                    state->currPacketState = CONNECT_TYPE;
                    state->keepAliveValue = DEFAULT_MQTT_KEEPALIVE;
                    state->connectFailCount = 0;
                    state->connectTick = 0;
                }
            }
        }
    }
	return state;
}

extern TRANSPORT_LL_HANDLE IoTHubTransportMqtt_Create(const IOTHUBTRANSPORT_CONFIG* config)
{
	PMQTTTRANSPORT_HANDLE_DATA result;
	size_t deviceIdSize;

	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_001: [If parameter config is NULL then IoTHubTransportMqtt_Create shall return NULL.] */
	if (config == NULL)
	{
		LogError("Invalid Argument: Config Parameter is NULL.");
		result = NULL;
	}
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_002: [If the parameter config's variables upperConfig or waitingToSend are NULL then IoTHubTransportMqtt_Create shall return NULL.] */
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_003: [If the upperConfig's variables deviceId, both deviceKey and deviceSasToken, iotHubName, protocol, or iotHubSuffix are NULL then IoTHubTransportMqtt_Create shall return NULL.] */
	else if (config->upperConfig == NULL || config->upperConfig->protocol == NULL || config->upperConfig->deviceId == NULL || ((config->upperConfig->deviceKey == NULL) && (config->upperConfig->deviceSasToken == NULL)) ||
		config->upperConfig->iotHubName == NULL || config->upperConfig->iotHubSuffix == NULL)
	{
		LogError("Invalid Argument: upperConfig structure contains an invalid parameter");
		result = NULL;
	}
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_002: [If the parameter config's variables upperConfig or waitingToSend are NULL then IoTHubTransportMqtt_Create shall return NULL.] */
	else if (config->waitingToSend == NULL)
	{
		LogError("Invalid Argument: waitingToSend is NULL)");
		result = NULL;
	}
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_006: [If the upperConfig's variables deviceId is an empty strings or length is greater then 128 then IoTHubTransportMqtt_Create shall return NULL.] */
	else if ( ( (deviceIdSize = strlen(config->upperConfig->deviceId)) > 128U) || (deviceIdSize == 0) )
	{
		LogError("Invalid Argument: DeviceId is of an invalid size");
		result = NULL;
	}
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_003: [If the upperConfig's variables deviceId, both deviceKey and deviceSasToken, iotHubName, protocol, or iotHubSuffix are NULL then IoTHubTransportMqtt_Create shall return NULL.] */
	else if ((config->upperConfig->deviceKey != NULL) && (strlen(config->upperConfig->deviceKey) == 0))
	{
		LogError("Invalid Argument: deviceKey is empty");
		result = NULL;
	}
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_003: [If the upperConfig's variables deviceId, both deviceKey and deviceSasToken, iotHubName, protocol, or iotHubSuffix are NULL then IoTHubTransportMqtt_Create shall return NULL.] */
	else if ((config->upperConfig->deviceSasToken != NULL) && (strlen(config->upperConfig->deviceSasToken) == 0))
	{
		LogError("Invalid Argument: deviceSasToken is empty");
		result = NULL;
	}
    /* Codes_SRS_IOTHUB_MQTT_TRANSPORT_03_003: [If both deviceKey & deviceSasToken fields are NOT NULL then IoTHubTransportMqtt_Create shall return NULL.] */
    else if ((config->upperConfig->deviceKey != NULL) && (config->upperConfig->deviceSasToken != NULL))
    {
        LogError("Invalid Argument: cannot have both deviceKey and deviceSasToken defined");
        result = NULL;
    }
    /* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_003: [If the upperConfig's variables deviceId, deviceKey, iotHubName, protocol, or iotHubSuffix are NULL then IoTHubTransportMqtt_Create shall return NULL.] */
	else if (strlen(config->upperConfig->iotHubName) == 0)
	{
		LogError("Invalid Argument: iotHubName is empty");
		result = NULL;
	}
	else
	{
		result = InitializeTransportHandleData(config->upperConfig, config->waitingToSend);
		if (result != NULL)
		{
			g_msgTickCounter = tickcounter_create();
		}
	}
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_009: [If any error is encountered then IoTHubTransportMqtt_Create shall return NULL.] */
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_011: [On Success IoTHubTransportMqtt_Create shall return a non-NULL value.] */
	return result;
}

static void DisconnectFromClient(PMQTTTRANSPORT_HANDLE_DATA transportState)
{
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_013: [If the parameter subscribe is true then IoTHubTransportMqtt_Destroy shall call IoTHubTransportMqtt_Unsubscribe.] */
	if (transportState->subscribed)
	{
		IoTHubTransportMqtt_Unsubscribe(transportState);
	}

	(void)mqtt_client_disconnect(transportState->mqttClient);
	xio_destroy(transportState->xioTransport);
	transportState->xioTransport = NULL;

	transportState->connected = false;
	transportState->currPacketState = DISCONNECT_TYPE;
}

void IoTHubTransportMqtt_Destroy(TRANSPORT_LL_HANDLE handle)
{
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_012: [IoTHubTransportMqtt_Destroy shall do nothing if parameter handle is NULL.] */
	PMQTTTRANSPORT_HANDLE_DATA transportState = (PMQTTTRANSPORT_HANDLE_DATA)handle;
	if (transportState != NULL)
	{
		transportState->destroyCalled = true;

		DisconnectFromClient(transportState);

		//Empty the Waiting for Ack Messages.
		while (!DList_IsListEmpty(&transportState->waitingForAck))
		{
			PDLIST_ENTRY currentEntry = DList_RemoveHeadList(&transportState->waitingForAck);
			MQTT_MESSAGE_DETAILS_LIST* mqttMsgEntry = containingRecord(currentEntry, MQTT_MESSAGE_DETAILS_LIST, entry);
			sendMsgComplete(mqttMsgEntry->iotHubMessageEntry, transportState, IOTHUB_BATCHSTATE_FAILED);
			free(mqttMsgEntry);
		}

		/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_014: [IoTHubTransportMqtt_Destroy shall free all the resources currently in use.] */
		mqtt_client_deinit(transportState->mqttClient);
		STRING_delete(transportState->mqttEventTopic);
		STRING_delete(transportState->mqttMessageTopic);
		STRING_delete(transportState->device_id);
		STRING_delete(transportState->device_key);
		STRING_delete(transportState->sasTokenSr);
		STRING_delete(transportState->hostAddress);
		STRING_delete(transportState->configPassedThroughUsername);
		tickcounter_destroy(g_msgTickCounter);
		free(transportState);
	}
}

int IoTHubTransportMqtt_Subscribe(IOTHUB_DEVICE_HANDLE handle)
{
	int result;
	PMQTTTRANSPORT_HANDLE_DATA transportState = (PMQTTTRANSPORT_HANDLE_DATA)handle;
	if (transportState == NULL)
	{
		/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_015: [If parameter handle is NULL than IoTHubTransportMqtt_Subscribe shall return a non-zero value.] */
		LogError("Invalid handle parameter. NULL.");
		result = __LINE__;
	}
	else
	{
		/* Code_SRS_IOTHUB_MQTT_TRANSPORT_07_016: [IoTHubTransportMqtt_Subscribe shall set a flag to enable mqtt_client_subscribe to be called to subscribe to the Message Topic.] */
		transportState->receiveMessages = true;
		/* Code_SRS_IOTHUB_MQTT_TRANSPORT_07_035: [If current packet state is not CONNACT, DISCONNECT_TYPE, or PACKET_TYPE_ERROR then IoTHubTransportMqtt_Subscribe shall set the packet state to SUBSCRIBE_TYPE.]*/
		if (transportState->currPacketState != CONNACK_TYPE &&
			transportState->currPacketState != CONNECT_TYPE &&
			transportState->currPacketState != DISCONNECT_TYPE &&
			transportState->currPacketState != PACKET_TYPE_ERROR)
		{
			transportState->currPacketState = SUBSCRIBE_TYPE;
		}
		result = 0;
	}
	return result;
}

void IoTHubTransportMqtt_Unsubscribe(IOTHUB_DEVICE_HANDLE handle)
{
	PMQTTTRANSPORT_HANDLE_DATA transportState = (PMQTTTRANSPORT_HANDLE_DATA)handle;
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_019: [If parameter handle is NULL then IoTHubTransportMqtt_Unsubscribe shall do nothing.] */
	if (transportState != NULL && transportState->subscribed)
	{
		/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_020: [IoTHubTransportMqtt_Unsubscribe shall call mqtt_client_unsubscribe to unsubscribe the mqtt message topic.] */
		const char* unsubscribe[] = { STRING_c_str(transportState->mqttMessageTopic) };
		(void)mqtt_client_unsubscribe(transportState->mqttClient, transportState->packetId++, unsubscribe, 1);
		transportState->subscribed = false;
		transportState->receiveMessages = false;
	}
	else
	{
		LogError("Invalid argument to unsubscribe (NULL).");
	}
}

extern void IoTHubTransportMqtt_DoWork(TRANSPORT_LL_HANDLE handle, IOTHUB_CLIENT_LL_HANDLE iotHubClientHandle)
{
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_026: [IoTHubTransportMqtt_DoWork shall do nothing if parameter handle and/or iotHubClientHandle is NULL.] */
	PMQTTTRANSPORT_HANDLE_DATA transportState = (PMQTTTRANSPORT_HANDLE_DATA)handle;
	if (transportState != NULL && iotHubClientHandle != NULL)
	{
		transportState->llClientHandle = iotHubClientHandle;

		if (InitializeConnection(transportState) != 0)
		{
			// Don't want to flood the logs with failures here
		}
		else
		{
			if (transportState->currPacketState == CONNACK_TYPE || transportState->currPacketState == SUBSCRIBE_TYPE)
			{
				(void)SubscribeToMqttProtocol(transportState);
			}
			else if (transportState->currPacketState == SUBACK_TYPE)
			{
				// Publish can be called now
				transportState->currPacketState = PUBLISH_TYPE;
			}
			else if (transportState->currPacketState == PUBLISH_TYPE)
			{
				PDLIST_ENTRY currentListEntry = transportState->waitingForAck.Flink;
				while (currentListEntry != &transportState->waitingForAck)
				{
					MQTT_MESSAGE_DETAILS_LIST* mqttMsgEntry = containingRecord(currentListEntry, MQTT_MESSAGE_DETAILS_LIST, entry);
					DLIST_ENTRY nextListEntry;
					nextListEntry.Flink = currentListEntry->Flink;

					uint64_t current_ms;
					(void)tickcounter_get_current_ms(g_msgTickCounter, &current_ms);
					/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_033: [IoTHubTransportMqtt_DoWork shall iterate through the Waiting Acknowledge messages looking for any message that has been waiting longer than 2 min.]*/
					if (((current_ms - mqttMsgEntry->msgPublishTime) / 1000) > RESEND_TIMEOUT_VALUE_MIN)
					{
						/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_034: [If IoTHubTransportMqtt_DoWork has resent the message two times then it shall fail the message] */
						if (mqttMsgEntry->retryCount >= MAX_SEND_RECOUNT_LIMIT)
						{
							(void)DList_RemoveEntryList(currentListEntry);
							sendMsgComplete(mqttMsgEntry->iotHubMessageEntry, transportState, IOTHUB_BATCHSTATE_FAILED);
							free(mqttMsgEntry);
						}
						else
						{
							size_t messageLength;
							const unsigned char* messagePayload = RetrieveMessagePayload(mqttMsgEntry->iotHubMessageEntry->messageHandle, &messageLength);
							if (messageLength == 0 || messagePayload == NULL)
							{
								LogError("Failure from creating Message IoTHubMessage_GetData");
							}
							else
							{
								if (publishMqttMessage(transportState, mqttMsgEntry, messagePayload, messageLength) != 0)
								{
									(void)DList_RemoveEntryList(currentListEntry);
									sendMsgComplete(mqttMsgEntry->iotHubMessageEntry, transportState, IOTHUB_BATCHSTATE_FAILED);
									free(mqttMsgEntry);
								}
							}
						}
					}
					currentListEntry = nextListEntry.Flink;
				}

				currentListEntry = transportState->waitingToSend->Flink;
				/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_027: [IoTHubTransportMqtt_DoWork shall inspect the “waitingToSend” DLIST passed in config structure.] */
				while (currentListEntry != transportState->waitingToSend)
				{
					IOTHUB_MESSAGE_LIST* iothubMsgList = containingRecord(currentListEntry, IOTHUB_MESSAGE_LIST, entry);
					DLIST_ENTRY savedFromCurrentListEntry;
					savedFromCurrentListEntry.Flink = currentListEntry->Flink;

					/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_027: [IoTHubTransportMqtt_DoWork shall inspect the “waitingToSend” DLIST passed in config structure.] */
					size_t messageLength;
					const unsigned char* messagePayload = RetrieveMessagePayload(iothubMsgList->messageHandle, &messageLength);
					if (messageLength == 0 || messagePayload == NULL)
					{
						LogError("Failure result from IoTHubMessage_GetData");
					}
					else
					{
						/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_029: [IoTHubTransportMqtt_DoWork shall create a MQTT_MESSAGE_HANDLE and pass this to a call to mqtt_client_publish.] */
						MQTT_MESSAGE_DETAILS_LIST* mqttMsgEntry = (MQTT_MESSAGE_DETAILS_LIST*)malloc(sizeof(MQTT_MESSAGE_DETAILS_LIST));
						if (mqttMsgEntry == NULL)
						{
							LogError("Allocation Error: Failure allocating MQTT Message Detail List.");
						}
						else
						{
							mqttMsgEntry->retryCount = 0;
							mqttMsgEntry->msgPacketId = transportState->packetId;
							mqttMsgEntry->iotHubMessageEntry = iothubMsgList;

							if (publishMqttMessage(transportState, mqttMsgEntry, messagePayload, messageLength) != 0)
							{
								(void)(DList_RemoveEntryList(currentListEntry));
								sendMsgComplete(iothubMsgList, transportState, IOTHUB_BATCHSTATE_FAILED);
								free(mqttMsgEntry);
							}
							else
							{
								(void)(DList_RemoveEntryList(currentListEntry));
								DList_InsertTailList(&(transportState->waitingForAck), &(mqttMsgEntry->entry));
							}
						}
					}
					currentListEntry = savedFromCurrentListEntry.Flink;
				}
			}
			/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_030: [IoTHubTransportMqtt_DoWork shall call mqtt_client_dowork everytime it is called if it is connected.] */
			mqtt_client_dowork(transportState->mqttClient);
		}
	}
}

IOTHUB_CLIENT_RESULT IoTHubTransportMqtt_GetSendStatus(IOTHUB_DEVICE_HANDLE handle, IOTHUB_CLIENT_STATUS *iotHubClientStatus)
{
	IOTHUB_CLIENT_RESULT result;

	if (handle == NULL || iotHubClientStatus == NULL)
	{
		/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_023: [IoTHubTransportMqtt_GetSendStatus shall return IOTHUB_CLIENT_INVALID_ARG if called with NULL parameter.] */
		LogError("invalid arument.");
		result = IOTHUB_CLIENT_INVALID_ARG;
	}
	else
	{
		MQTTTRANSPORT_HANDLE_DATA* handleData = (MQTTTRANSPORT_HANDLE_DATA*)handle;
		if (!DList_IsListEmpty(handleData->waitingToSend) || !DList_IsListEmpty(&(handleData->waitingForAck)))
		{
			/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_025: [IoTHubTransportMqtt_GetSendStatus shall return IOTHUB_CLIENT_OK and status IOTHUB_CLIENT_SEND_STATUS_BUSY if there are currently event items to be sent or being sent.] */
			*iotHubClientStatus = IOTHUB_CLIENT_SEND_STATUS_BUSY;
		}
		else
		{
			/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_024: [IoTHubTransportMqtt_GetSendStatus shall return IOTHUB_CLIENT_OK and status IOTHUB_CLIENT_SEND_STATUS_IDLE if there are currently no event items to be sent or being sent.] */
			*iotHubClientStatus = IOTHUB_CLIENT_SEND_STATUS_IDLE;
		}
		result = IOTHUB_CLIENT_OK;
	}
	return result;
}

IOTHUB_CLIENT_RESULT IoTHubTransportMqtt_SetOption(TRANSPORT_LL_HANDLE handle, const char* option, const void* value)
{
	/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_021: [If any parameter is NULL then IoTHubTransportMqtt_SetOption shall return IOTHUB_CLIENT_INVALID_ARG.] */
	IOTHUB_CLIENT_RESULT result;
	if (
		(handle == NULL) ||
		(option == NULL) ||
		(value == NULL)
		)
	{
		result = IOTHUB_CLIENT_INVALID_ARG;
		LogError("invalid parameter (NULL) passed to clientTransportAMQP_SetOption.");
	}
	else
	{
		MQTTTRANSPORT_HANDLE_DATA* transportState = (MQTTTRANSPORT_HANDLE_DATA*)handle;
		/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_031: [If the option parameter is set to "logtrace" then the value shall be a bool_ptr and the value will determine if the mqtt client log is on or off.] */
		if (strcmp("logtrace", option) == 0)
		{
			bool* traceVal = (bool*)value;
			mqtt_client_set_trace(transportState->mqttClient, *traceVal, *traceVal);
			result = IOTHUB_CLIENT_OK;
		}
		else if (strcmp("keepalive", option) == 0)
		{
			/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_036: [If the option parameter is set to "keepalive" then the value shall be a int_ptr and the value will determine the mqtt keepalive time that is set for pings.] */
			int* keepAliveOption = (int*)value;
			/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_037 : [If the option parameter is set to supplied int_ptr keepalive is the same value as the existing keepalive then IoTHubTransportMqtt_SetOption shall do nothing.] */
			if (*keepAliveOption != transportState->keepAliveValue)
			{
				transportState->keepAliveValue = *keepAliveOption;
				if (transportState->connected)
				{
					/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_038: [If the client is connected when the keepalive is set then IoTHubTransportMqtt_SetOption shall disconnect and reconnect with the specified keepalive value.] */
					DisconnectFromClient(transportState);
				}
			}
			result = IOTHUB_CLIENT_OK;
		}
		else
		{
			/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_032: [IoTHubTransportMqtt_SetOption shall pass down the option to xio_setoption if the option parameter is not a known option string for the MQTT transport.] */
			if (GetTransportProviderIfNecessary(transportState) == 0)
			{
				if (xio_setoption(transportState->xioTransport, option, value) == 0)
				{
					result = IOTHUB_CLIENT_OK;
				}
				else
				{
					/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_132: [IoTHubTransportMqtt_SetOption shall return IOTHUB_CLIENT_INVALID_ARG xio_setoption fails] */
					result = IOTHUB_CLIENT_INVALID_ARG;
				}
			}
			else
			{
				result = IOTHUB_CLIENT_ERROR;
			}
		}
	}
	return result;
}

IOTHUB_DEVICE_HANDLE IoTHubTransportMqtt_Register(TRANSPORT_LL_HANDLE handle, const IOTHUB_DEVICE_CONFIG* device, IOTHUB_CLIENT_LL_HANDLE iotHubClientHandle, PDLIST_ENTRY waitingToSend)
{
	IOTHUB_DEVICE_HANDLE result;
	// Codes_SRS_IOTHUB_MQTT_TRANSPORT_17_001: [ IoTHubTransportMqtt_Register shall return NULL if the TRANSPORT_LL_HANDLE is NULL.]
	// Codes_SRS_IOTHUB_MQTT_TRANSPORT_17_002: [ IoTHubTransportMqtt_Register shall return NULL if device or waitingToSend are NULL.]
	if ((handle == NULL) || (device == NULL) || (waitingToSend == NULL))
	{
        LogError("IoTHubTransportMqtt_Register: handle, device or waitingToSend is NULL.");
        result = NULL;
	}
	else
	{
		MQTTTRANSPORT_HANDLE_DATA* transportState = (MQTTTRANSPORT_HANDLE_DATA*)handle;

		// Codes_SRS_IOTHUB_MQTT_TRANSPORT_03_001: [ IoTHubTransportMqtt_Register shall return NULL if deviceId, or both deviceKey and deviceSasToken are NULL.]
		if (device->deviceId == NULL)
		{
            LogError("IoTHubTransportMqtt_Register: deviceId is NULL.");
            result = NULL;
		}
		else if ((device->deviceKey == NULL) && (device->deviceSasToken == NULL))
		{
            LogError("IoTHubTransportMqtt_Register: deviceKey and deviceSasToken are NULL.");
            result = NULL;
		}
		// Codes_SRS_IOTHUB_MQTT_TRANSPORT_03_002: [ IoTHubTransportMqtt_Register shall return NULL if both deviceKey and deviceSasToken are provided.]
		else if ((device->deviceKey != NULL) && (device->deviceSasToken != NULL))
		{
            LogError("IoTHubTransportMqtt_Register: Both deviceKey and deviceSasToken are defined. Only one can be used.");
            result = NULL;
		}
		else
		{
			// Codes_SRS_IOTHUB_MQTT_TRANSPORT_17_003: [ IoTHubTransportMqtt_Register shall return NULL if deviceId or deviceKey do not match the deviceId and deviceKey passed in during IoTHubTransportMqtt_Create.]
			if (strcmp(STRING_c_str(transportState->device_id), device->deviceId) != 0)
			{
                LogError("IoTHubTransportMqtt_Register: deviceId does not match.");
                result = NULL;
			}
			else if ((device->deviceKey != NULL) && (strcmp(STRING_c_str(transportState->device_key), device->deviceKey) != 0))
			{
                LogError("IoTHubTransportMqtt_Register: deviceKey does not match.");
                result = NULL;
			}
			else
			{
				if (transportState->isRegistered == true)
				{
					LogError("Transport already has device registered by id: [%s]", device->deviceId);
					result = NULL;
				}
				else
				{
					transportState->isRegistered = true;
					// Codes_SRS_IOTHUB_MQTT_TRANSPORT_17_004: [ IoTHubTransportMqtt_Register shall return the TRANSPORT_LL_HANDLE as the IOTHUB_DEVICE_HANDLE. ]
					result = (IOTHUB_DEVICE_HANDLE)handle;
				}
			}
		}
	}

	return result;
}

// Codes_SRS_IOTHUB_MQTT_TRANSPORT_17_005: [ IoTHubTransportMqtt_Unregister shall return. ]
void IoTHubTransportMqtt_Unregister(IOTHUB_DEVICE_HANDLE deviceHandle)
{
	if (deviceHandle != NULL)
	{
		MQTTTRANSPORT_HANDLE_DATA* transportState = (MQTTTRANSPORT_HANDLE_DATA*)deviceHandle;

		transportState->isRegistered = false;
	}
}

TRANSPORT_PROVIDER myfunc = {
	IoTHubTransportMqtt_SetOption,
	IoTHubTransportMqtt_Create,
	IoTHubTransportMqtt_Destroy,
	IoTHubTransportMqtt_Register,
	IoTHubTransportMqtt_Unregister,
	IoTHubTransportMqtt_Subscribe,
	IoTHubTransportMqtt_Unsubscribe,
	IoTHubTransportMqtt_DoWork,
	IoTHubTransportMqtt_GetSendStatus
};

/* Codes_SRS_IOTHUB_MQTT_TRANSPORT_07_022: [This function shall return a pointer to a structure of type TRANSPORT_PROVIDER having the following values for it’s fields: IoTHubTransport_Create = IoTHubTransportMqtt_Create
IoTHubTransport_Destroy = IoTHubTransportMqtt_Destroy
IoTHubTransport_Subscribe = IoTHubTransportMqtt_Subscribe
IoTHubTransport_Unsubscribe = IoTHubTransportMqtt_Unsubscribe
IoTHubTransport_DoWork = IoTHubTransportMqtt_DoWork
IoTHubTransport_SetOption = IoTHubTransportMqtt_SetOption] */
extern const void* MQTT_Protocol(void)
{
	return &myfunc;
}