ArduinoIoTCloudTCP.cpp

/*
   This file is part of ArduinoIoTCloud.

   Copyright 2019 ARDUINO SA (http://www.arduino.cc/)

   This software is released under the GNU General Public License version 3,
   which covers the main part of arduino-cli.
   The terms of this license can be found at:
   https://www.gnu.org/licenses/gpl-3.0.en.html

   You can be released from the requirements of the above licenses by purchasing
   a commercial license. Buying such a license is mandatory if you want to modify or
   otherwise use the software for commercial activities involving the Arduino
   software without disclosing the source code of your own applications. To purchase
   a commercial license, send an email to license@arduino.cc.
*/

/******************************************************************************
 * INCLUDE
 ******************************************************************************/

#include <AIoTC_Config.h>

#ifdef HAS_TCP
#include <ArduinoIoTCloudTCP.h>
#ifdef BOARD_HAS_ECCX08
  #include "tls/BearSSLTrustAnchors.h"
  #include "tls/utility/CryptoUtil.h"
#endif

#ifdef BOARD_HAS_SE050
  #include "tls/AIoTCSSCert.h"
  #include "tls/utility/CryptoUtil.h"
#endif

#ifdef BOARD_HAS_OFFLOADED_ECCX08
#include <ArduinoECCX08.h>
#include "tls/utility/CryptoUtil.h"
#endif

#if defined(ARDUINO_PORTENTA_H7_M7) || defined(ARDUINO_PORTENTA_H7_M4)
#  include "tls/utility/SHA256.h"
#  include <stm32h7xx_hal_rtc_ex.h>
#  include <WiFi.h>
#endif

#include "utility/ota/OTA.h"
#include "utility/ota/FlashSHA256.h"
#include <algorithm>
#include "cbor/CBOREncoder.h"

#include "utility/watchdog/Watchdog.h"


/******************************************************************************
 * EXTERN
 ******************************************************************************/

#if defined(ARDUINO_PORTENTA_H7_M7)
extern RTC_HandleTypeDef RTCHandle;
#endif

/******************************************************************************
   LOCAL MODULE FUNCTIONS
 ******************************************************************************/

unsigned long getTime()
{
  return ArduinoCloud.getInternalTime();
}

void updateTimezoneInfo()
{
  ArduinoCloud.updateInternalTimezoneInfo();
}

void setThingIdOutdated()
{
  ArduinoCloud.setThingIdOutdatedFlag();
}

/******************************************************************************
   CTOR/DTOR
 ******************************************************************************/

ArduinoIoTCloudTCP::ArduinoIoTCloudTCP()
: _state{State::ConnectPhy}
, _next_connection_attempt_tick{0}
, _last_connection_attempt_cnt{0}
, _next_device_subscribe_attempt_tick{0}
, _last_device_subscribe_cnt{0}
, _last_sync_request_tick{0}
, _last_sync_request_cnt{0}
, _last_subscribe_request_tick{0}
, _last_subscribe_request_cnt{0}
, _mqtt_data_buf{0}
, _mqtt_data_len{0}
, _mqtt_data_request_retransmit{false}
#ifdef BOARD_HAS_ECCX08
, _sslClient(nullptr, ArduinoIoTCloudTrustAnchor, ArduinoIoTCloudTrustAnchor_NUM, getTime)
#endif
  #ifdef BOARD_ESP
, _password("")
  #endif
, _mqttClient{nullptr}
, _deviceTopicOut("")
, _deviceTopicIn("")
, _shadowTopicOut("")
, _shadowTopicIn("")
, _dataTopicOut("")
, _dataTopicIn("")
, _deviceSubscribedToThing{false}
#if OTA_ENABLED
, _ota_cap{false}
, _ota_error{static_cast<int>(OTAError::None)}
, _ota_img_sha256{"Inv."}
, _ota_url{""}
, _ota_req{false}
, _ask_user_before_executing_ota{false}
, _get_ota_confirmation{nullptr}
#endif /* OTA_ENABLED */
{

}

/******************************************************************************
 * PUBLIC MEMBER FUNCTIONS
 ******************************************************************************/

int ArduinoIoTCloudTCP::begin(ConnectionHandler & connection, bool const enable_watchdog, String brokerAddress, uint16_t brokerPort)
{
  _connection = &connection;
  _brokerAddress = brokerAddress;
  _brokerPort = brokerPort;
  _time_service.begin(&connection);
  return begin(enable_watchdog, _brokerAddress, _brokerPort);
}

int ArduinoIoTCloudTCP::begin(bool const enable_watchdog, String brokerAddress, uint16_t brokerPort)
{
  _brokerAddress = brokerAddress;
  _brokerPort = brokerPort;

#if defined(__AVR__)
  String const nina_fw_version = WiFi.firmwareVersion();
  if (nina_fw_version < "1.4.2")
  {
    DEBUG_ERROR("ArduinoIoTCloudTCP::%s NINA firmware needs to be >= 1.4.2 to support cloud on Uno WiFi Rev. 2, current %s", __FUNCTION__, nina_fw_version.c_str());
    return 0;
  }
#endif /* AVR */

#if OTA_ENABLED && !defined(__AVR__)
#if defined(ARDUINO_PORTENTA_H7_M7)
  /* The length of the application can be retrieved the same way it was
   * communicated to the bootloader, that is by writing to the non-volatile
   * storage registers of the RTC.
   */
  SHA256         sha256;
  uint32_t const app_start = 0x8040000;
  uint32_t const app_size  = HAL_RTCEx_BKUPRead(&RTCHandle, RTC_BKP_DR3);

  sha256.begin();
  uint32_t b = 0;
  uint32_t bytes_read = 0; for(uint32_t a = app_start;
                               bytes_read < app_size;
                               bytes_read += sizeof(b), a += sizeof(b))
  {
    /* Read the next chunk of memory. */
    memcpy(&b, reinterpret_cast<const void *>(a), sizeof(b));
    /* Feed it to SHA256. */
    sha256.update(reinterpret_cast<uint8_t *>(&b), sizeof(b));
  }
  /* Retrieve the final hash string. */
  uint8_t sha256_hash[SHA256::HASH_SIZE] = {0};
  sha256.finalize(sha256_hash);
  String sha256_str;
  std::for_each(sha256_hash,
                sha256_hash + SHA256::HASH_SIZE,
                [&sha256_str](uint8_t const elem)
                {
                  char buf[4];
                  snprintf(buf, 4, "%02X", elem);
                  sha256_str += buf;
                });
  DEBUG_VERBOSE("SHA256: %d bytes (of %d) read", bytes_read, app_size);
#elif defined(ARDUINO_ARCH_SAMD)
  /* Calculate the SHA256 checksum over the firmware stored in the flash of the
   * MCU. Note: As we don't know the length per-se we read chunks of the flash
   * until we detect one containing only 0xFF (= flash erased). This only works
   * for firmware updated via OTA and second stage bootloaders (SxU family)
   * because only those erase the complete flash before performing an update.
   * Since the SHA256 firmware image is only required for the cloud servers to
   * perform a version check after the OTA update this is a acceptable trade off.
   * The bootloader is excluded from the calculation and occupies flash address
   * range 0 to 0x2000, total flash size of 0x40000 bytes (256 kByte).
   */
  String const sha256_str = FlashSHA256::calc(0x2000, 0x40000 - 0x2000);
#elif defined(ARDUINO_NANO_RP2040_CONNECT)
  /* The maximum size of a RP2040 OTA update image is 1 MByte (that is 1024 *
   * 1024 bytes or 0x100'000 bytes).
   */
  String const sha256_str = FlashSHA256::calc(XIP_BASE, 0x100000);
#else
# error "No method for SHA256 checksum calculation over application image defined for this architecture."
#endif
  DEBUG_VERBOSE("SHA256: HASH(%d) = %s", strlen(sha256_str.c_str()), sha256_str.c_str());
  _ota_img_sha256 = sha256_str;
#endif /* OTA_ENABLED */

#if defined(BOARD_HAS_ECCX08) || defined(BOARD_HAS_OFFLOADED_ECCX08) || defined(BOARD_HAS_SE050)
  if (!_crypto.begin())
  {
    DEBUG_ERROR("_crypto.begin() failed.");
    return 0;
  }
  if (!_crypto.readDeviceId(getDeviceId(), CryptoSlot::DeviceId))
  {
    DEBUG_ERROR("_crypto.readDeviceId(...) failed.");
    return 0;
  }
#endif

#if defined(BOARD_HAS_ECCX08) || defined(BOARD_HAS_SE050)
  if (!_crypto.readCert(_cert, CryptoSlot::CompressedCertificate))
  {
    DEBUG_ERROR("Cryptography certificate reconstruction failure.");
    return 0;
  }
  _sslClient.setEccSlot(static_cast<int>(CryptoSlot::Key), _cert.bytes(), _cert.length());
#endif

#if defined(BOARD_HAS_ECCX08)
  _sslClient.setClient(_connection->getClient());
#elif defined(BOARD_HAS_SE050)
  _sslClient.appendCustomCACert(AIoTSSCert);
#elif defined(BOARD_ESP)
  _sslClient.setInsecure();
#endif

  _mqttClient.setClient(_sslClient);
#ifdef BOARD_ESP
  _mqttClient.setUsernamePassword(getDeviceId(), _password);
#endif
  _mqttClient.onMessage(ArduinoIoTCloudTCP::onMessage);
  _mqttClient.setKeepAliveInterval(30 * 1000);
  _mqttClient.setConnectionTimeout(1500);
  _mqttClient.setId(getDeviceId().c_str());

  _deviceTopicOut = getTopic_deviceout();
  _deviceTopicIn  = getTopic_devicein();

  addPropertyReal(_lib_version, _device_property_container, "LIB_VERSION", Permission::Read);
#if OTA_ENABLED
  addPropertyReal(_ota_cap, _device_property_container, "OTA_CAP", Permission::Read);
  addPropertyReal(_ota_error, _device_property_container, "OTA_ERROR", Permission::Read);
  addPropertyReal(_ota_img_sha256, _device_property_container, "OTA_SHA256", Permission::Read);
  addPropertyReal(_ota_url, _device_property_container, "OTA_URL", Permission::ReadWrite);
  addPropertyReal(_ota_req, _device_property_container, "OTA_REQ", Permission::ReadWrite);
#endif /* OTA_ENABLED */

  addPropertyReal(_tz_offset, _thing_property_container, "tz_offset", Permission::ReadWrite).onSync(CLOUD_WINS).onUpdate(updateTimezoneInfo);
  addPropertyReal(_tz_dst_until, _thing_property_container, "tz_dst_until", Permission::ReadWrite).onSync(CLOUD_WINS).onUpdate(updateTimezoneInfo);
  addPropertyReal(_thing_id, _device_property_container, "thing_id", Permission::ReadWrite).onUpdate(setThingIdOutdated);

#if OTA_STORAGE_PORTENTA_QSPI
  #define BOOTLOADER_ADDR   (0x8000000)
  uint32_t bootloader_data_offset = 0x1F000;
  uint8_t* bootloader_data = (uint8_t*)(BOOTLOADER_ADDR + bootloader_data_offset);
  uint8_t currentBootloaderVersion = bootloader_data[1];
  if (currentBootloaderVersion < 22) {
    _ota_cap = false;
    DEBUG_WARNING("ArduinoIoTCloudTCP::%s In order to be ready for cloud OTA, update the bootloader", __FUNCTION__);
    DEBUG_WARNING("ArduinoIoTCloudTCP::%s File -> Examples -> Portenta_System -> PortentaH7_updateBootloader", __FUNCTION__);
  }
  else {
    _ota_cap = true;
  }
#endif

#if OTA_STORAGE_SNU && OTA_ENABLED
  if (String(WiFi.firmwareVersion()) < String("1.4.1")) {
    _ota_cap = false;
    DEBUG_WARNING("ArduinoIoTCloudTCP::%s In order to be ready for cloud OTA, NINA firmware needs to be >= 1.4.1, current %s", __FUNCTION__, WiFi.firmwareVersion());
  }
  else {
    _ota_cap = true;
  }
#endif /* OTA_STORAGE_SNU */

#if defined(ARDUINO_NANO_RP2040_CONNECT)
  _ota_cap = true;
#endif

#ifdef BOARD_HAS_OFFLOADED_ECCX08
  if (String(WiFi.firmwareVersion()) < String("1.4.4")) {
    DEBUG_ERROR("ArduinoIoTCloudTCP::%s In order to connect to Arduino IoT Cloud, NINA firmware needs to be >= 1.4.4, current %s", __FUNCTION__, WiFi.firmwareVersion());
    return 0;
  }
#endif /* BOARD_HAS_OFFLOADED_ECCX08 */

  /* Since we do not control what code the user inserts
   * between ArduinoIoTCloudTCP::begin() and the first
   * call to ArduinoIoTCloudTCP::update() it is wise to
   * set a rather large timeout at first.
   */
#if defined (ARDUINO_ARCH_SAMD) || defined (ARDUINO_ARCH_MBED)
  if (enable_watchdog) {
    watchdog_enable();
#if defined (WIFI_HAS_FEED_WATCHDOG_FUNC) || defined (ARDUINO_PORTENTA_H7_WIFI_HAS_FEED_WATCHDOG_FUNC)
      WiFi.setFeedWatchdogFunc(watchdog_reset);
#endif
  }
#endif

  return 1;
}

void ArduinoIoTCloudTCP::update()
{
  /* Feed the watchdog. If any of the functions called below
   * get stuck than we can at least reset and recover.
   */
#if defined (ARDUINO_ARCH_SAMD) || defined (ARDUINO_ARCH_MBED)
  watchdog_reset();
#endif


  /* Run through the state machine. */
  State next_state = _state;
  switch (_state)
  {
  case State::ConnectPhy:           next_state = handle_ConnectPhy();           break;
  case State::SyncTime:             next_state = handle_SyncTime();             break;
  case State::ConnectMqttBroker:    next_state = handle_ConnectMqttBroker();    break;
  case State::SendDeviceProperties: next_state = handle_SendDeviceProperties(); break;
  case State::SubscribeDeviceTopic: next_state = handle_SubscribeDeviceTopic(); break;
  case State::WaitDeviceConfig:     next_state = handle_WaitDeviceConfig();     break;
  case State::CheckDeviceConfig:    next_state = handle_CheckDeviceConfig();    break;
  case State::SubscribeThingTopics: next_state = handle_SubscribeThingTopics(); break;
  case State::RequestLastValues:    next_state = handle_RequestLastValues();    break;
  case State::Connected:            next_state = handle_Connected();            break;
  case State::Disconnect:           next_state = handle_Disconnect();           break;
  }
  _state = next_state;

  /* This watchdog feed is actually needed only by the RP2040 CONNECT cause its
   * maximum watchdog window is 8389ms; despite this we feed it for all 
   * supported ARCH to keep code aligned.
   */
#if defined (ARDUINO_ARCH_SAMD) || defined (ARDUINO_ARCH_MBED)
  watchdog_reset();
#endif

  /* Check for new data from the MQTT client. */
  if (_mqttClient.connected())
    _mqttClient.poll();
}

int ArduinoIoTCloudTCP::connected()
{
  return _mqttClient.connected();
}

void ArduinoIoTCloudTCP::printDebugInfo()
{
  DEBUG_INFO("***** Arduino IoT Cloud - configuration info *****");
  DEBUG_INFO("Device ID: %s", getDeviceId().c_str());
  DEBUG_INFO("MQTT Broker: %s:%d", _brokerAddress.c_str(), _brokerPort);
}

/******************************************************************************
 * PRIVATE MEMBER FUNCTIONS
 ******************************************************************************/

ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_ConnectPhy()
{
  if (_connection->check() == NetworkConnectionState::CONNECTED)
  {
    bool const is_retry_attempt = (_last_connection_attempt_cnt > 0);
    if (!is_retry_attempt || (is_retry_attempt && (millis() > _next_connection_attempt_tick)))
      return State::SyncTime;
  }

  return State::ConnectPhy;
}

ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_SyncTime()
{
  unsigned long const internal_posix_time = _time_service.getTime();
  DEBUG_VERBOSE("ArduinoIoTCloudTCP::%s internal clock configured to posix timestamp %d", __FUNCTION__, internal_posix_time);
  return State::ConnectMqttBroker;
}

ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_ConnectMqttBroker()
{
  if (_mqttClient.connect(_brokerAddress.c_str(), _brokerPort))
  {
    _last_connection_attempt_cnt = 0;
    return State::SendDeviceProperties;
  }

  _last_connection_attempt_cnt++;
  unsigned long reconnection_retry_delay = (1 << _last_connection_attempt_cnt) * AIOT_CONFIG_RECONNECTION_RETRY_DELAY_ms;
  reconnection_retry_delay = min(reconnection_retry_delay, static_cast<unsigned long>(AIOT_CONFIG_MAX_RECONNECTION_RETRY_DELAY_ms));
  _next_connection_attempt_tick = millis() + reconnection_retry_delay;

  DEBUG_ERROR("ArduinoIoTCloudTCP::%s could not connect to %s:%d", __FUNCTION__, _brokerAddress.c_str(), _brokerPort);
  DEBUG_ERROR("ArduinoIoTCloudTCP::%s %d connection attempt at tick time %d", __FUNCTION__, _last_connection_attempt_cnt, _next_connection_attempt_tick);
  return State::ConnectPhy;
}

ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_SendDeviceProperties()
{
  if (!_mqttClient.connected())
  {
    return State::Disconnect;
  }

  sendDevicePropertiesToCloud();
  return State::SubscribeDeviceTopic;
}

ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_SubscribeDeviceTopic()
{
  if (!_mqttClient.connected())
  {
    return State::Disconnect;
  }

  if (!_mqttClient.subscribe(_deviceTopicIn))
  {
    DEBUG_ERROR("ArduinoIoTCloudTCP::%s could not subscribe to %s", __FUNCTION__, _deviceTopicIn.c_str());
    return State::SubscribeDeviceTopic;
  }

  if (_last_device_subscribe_cnt > AIOT_CONFIG_LASTVALUES_SYNC_MAX_RETRY_CNT)
  {
    _last_device_subscribe_cnt = 0;
    _next_device_subscribe_attempt_tick = 0;
    _mqttClient.stop();
    execCloudEventCallback(ArduinoIoTCloudEvent::DISCONNECT);
    return State::ConnectPhy;
  }

  /* No device configuration reply. Wait: 5s -> 10s -> 20s -> 30s */
  unsigned long subscribe_retry_delay = (1 << _last_device_subscribe_cnt) * AIOT_CONFIG_DEVICE_TOPIC_SUBSCRIBE_RETRY_DELAY_ms;
  subscribe_retry_delay = min(subscribe_retry_delay, static_cast<unsigned long>(AIOT_CONFIG_MAX_DEVICE_TOPIC_SUBSCRIBE_RETRY_DELAY_ms));
  _next_device_subscribe_attempt_tick = millis() + subscribe_retry_delay;
  _last_device_subscribe_cnt++;

  return State::WaitDeviceConfig;
}

ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_WaitDeviceConfig()
{
  if (!_mqttClient.connected())
  {
    return State::Disconnect;
  }

  if (getThingIdOutdatedFlag())
  {
    return State::CheckDeviceConfig;
  }

  if (millis() > _next_device_subscribe_attempt_tick)
  {
    /* Configuration not received or device not attached to a valid thing. Try to resubscribe */
    if (_mqttClient.unsubscribe(_deviceTopicIn))
    {
      DEBUG_ERROR("ArduinoIoTCloudTCP::%s device waiting for valid thing_id", __FUNCTION__);
      return State::SubscribeDeviceTopic;
    }
  }
  return State::WaitDeviceConfig;
}

ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_CheckDeviceConfig()
{
  if (!_mqttClient.connected())
  {
    return State::Disconnect;
  }

  if(_deviceSubscribedToThing == true)
  {
    /* Unsubscribe from old things topics and go on with a new subsctiption */
    _mqttClient.unsubscribe(_shadowTopicIn);
    _mqttClient.unsubscribe(_dataTopicIn);
    _deviceSubscribedToThing = false;
    DEBUG_INFO("Disconnected from Arduino IoT Cloud");
    execCloudEventCallback(ArduinoIoTCloudEvent::DISCONNECT);
  }

  updateThingTopics();

  if (deviceNotAttached())
  {
    /* Configuration received but device not attached. Wait: 40s */
    unsigned long attach_retry_delay = (1 << _last_device_attach_cnt) * AIOT_CONFIG_DEVICE_TOPIC_SUBSCRIBE_RETRY_DELAY_ms;
    attach_retry_delay = min(attach_retry_delay, static_cast<unsigned long>(AIOT_CONFIG_MAX_DEVICE_TOPIC_ATTACH_RETRY_DELAY_ms));
    _next_device_subscribe_attempt_tick = millis() + attach_retry_delay;
    _last_device_attach_cnt++;
    return State::WaitDeviceConfig;
  }

  DEBUG_VERBOSE("ArduinoIoTCloudTCP::%s Device attached to a new valid Thing %s", __FUNCTION__, getThingId().c_str());
  _last_device_attach_cnt = 0;

  return State::SubscribeThingTopics;
}

ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_SubscribeThingTopics()
{
  if (!_mqttClient.connected())
  {
    return State::Disconnect;
  }

  if (getThingIdOutdatedFlag())
  {
    return State::CheckDeviceConfig;
  }

  unsigned long const now = millis();
  bool const is_subscribe_retry_delay_expired = (now - _last_subscribe_request_tick) > AIOT_CONFIG_THING_TOPICS_SUBSCRIBE_RETRY_DELAY_ms;
  bool const is_first_subscribe_request = (_last_subscribe_request_cnt == 0);

  if (!is_first_subscribe_request && !is_subscribe_retry_delay_expired)
  {
    return State::SubscribeThingTopics;
  }

  if (_last_subscribe_request_cnt > AIOT_CONFIG_THING_TOPICS_SUBSCRIBE_MAX_RETRY_CNT)
  {
    _last_subscribe_request_cnt = 0;
    _last_subscribe_request_tick = 0;
    _mqttClient.stop();
    execCloudEventCallback(ArduinoIoTCloudEvent::DISCONNECT);
    return State::ConnectPhy;
  }

  _last_subscribe_request_tick = now;
  _last_subscribe_request_cnt++;

  if (!_mqttClient.subscribe(_dataTopicIn))
  {
    DEBUG_ERROR("ArduinoIoTCloudTCP::%s could not subscribe to %s", __FUNCTION__, _dataTopicIn.c_str());
#if !defined(__AVR__)
    DEBUG_ERROR("Check your thing configuration, and press the reset button on your board.");
#endif
    return State::SubscribeThingTopics;
  }

  if (!_mqttClient.subscribe(_shadowTopicIn))
  {
    DEBUG_ERROR("ArduinoIoTCloudTCP::%s could not subscribe to %s", __FUNCTION__, _shadowTopicIn.c_str());
#if !defined(__AVR__)
    DEBUG_ERROR("Check your thing configuration, and press the reset button on your board.");
#endif
    return State::SubscribeThingTopics;
  }

  DEBUG_INFO("Connected to Arduino IoT Cloud");
  DEBUG_INFO("Thing ID: %s", getThingId().c_str());
  execCloudEventCallback(ArduinoIoTCloudEvent::CONNECT);
  _deviceSubscribedToThing = true;

  /*Add retry wait time otherwise we are trying to reconnect every 250ms...*/
  return State::RequestLastValues;
}

ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_RequestLastValues()
{
  if (!_mqttClient.connected())
  {
    return State::Disconnect;
  }

  if (getThingIdOutdatedFlag())
  {
    return State::CheckDeviceConfig;
  }

  /* Check whether or not we need to send a new request. */
  unsigned long const now = millis();
  bool const is_sync_request_timeout = (now - _last_sync_request_tick) > AIOT_CONFIG_TIMEOUT_FOR_LASTVALUES_SYNC_ms;
  bool const is_first_sync_request = (_last_sync_request_cnt == 0);
  if (is_first_sync_request || is_sync_request_timeout)
  {
    DEBUG_VERBOSE("ArduinoIoTCloudTCP::%s [%d] last values requested", __FUNCTION__, now);
    requestLastValue();
    _last_sync_request_tick = now;
    /* Track the number of times a get-last-values request was sent to the cloud.
     * If no data is received within a certain number of retry-requests it's a better
     * strategy to disconnect and re-establish connection from the ground up.
     */
    _last_sync_request_cnt++;
    if (_last_sync_request_cnt > AIOT_CONFIG_LASTVALUES_SYNC_MAX_RETRY_CNT)
    {
      _last_sync_request_cnt = 0;
      _last_sync_request_tick = 0;
      _mqttClient.stop();
      execCloudEventCallback(ArduinoIoTCloudEvent::DISCONNECT);
      return State::ConnectPhy;
    }
  }

  return State::RequestLastValues;
}

ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_Connected()
{
  if (!_mqttClient.connected())
  {
    /* The last message was definitely lost, trigger a retransmit. */
    _mqtt_data_request_retransmit = true;
    return State::Disconnect;
  }
  /* We are connected so let's to our stuff here. */
  else
  {
    if (getThingIdOutdatedFlag())
    {
      return State::CheckDeviceConfig;
    }

    /* Check if a primitive property wrapper is locally changed.
    * This function requires an existing time service which in
    * turn requires an established connection. Not having that
    * leads to a wrong time set in the time service which inhibits
    * the connection from being established due to a wrong data
    * in the reconstructed certificate.
    */
    updateTimestampOnLocallyChangedProperties(_thing_property_container);

    /* Retransmit data in case there was a lost transaction due
    * to phy layer or MQTT connectivity loss.
    */
    if(_mqtt_data_request_retransmit && (_mqtt_data_len > 0)) {
      write(_dataTopicOut, _mqtt_data_buf, _mqtt_data_len);
      _mqtt_data_request_retransmit = false;
    }

#if OTA_ENABLED
    /* Request a OTA download if the hidden property
     * OTA request has been set.
     */

    if (_ota_req)
    {
      bool const ota_execution_allowed_by_user = (_get_ota_confirmation != nullptr && _get_ota_confirmation());
      bool const perform_ota_now = ota_execution_allowed_by_user || !_ask_user_before_executing_ota;
      if (perform_ota_now) {
        /* Clear the error flag. */
        _ota_error = static_cast<int>(OTAError::None);
        /* Clear the request flag. */
        _ota_req = false;
        /* Transmit the cleared request flags to the cloud. */
        sendDevicePropertyToCloud("OTA_REQ");
        /* Call member function to handle OTA request. */
        onOTARequest();
        /* If something fails send the OTA error to the cloud */
        sendDevicePropertyToCloud("OTA_ERROR");
      }
    }

    /* Check if we have received the OTA_URL property and provide
    * echo to the cloud.
    */
    sendDevicePropertyToCloud("OTA_URL");

#endif /* OTA_ENABLED */

    /* Check if any properties need encoding and send them to
    * the cloud if necessary.
    */
    sendThingPropertiesToCloud();

    unsigned long const internal_posix_time = _time_service.getTime();
    if(internal_posix_time < _tz_dst_until) {
      return State::Connected;
    } else {
      return State::RequestLastValues;
    }
  }
}

ArduinoIoTCloudTCP::State ArduinoIoTCloudTCP::handle_Disconnect()
{
  DEBUG_ERROR("ArduinoIoTCloudTCP::%s MQTT client connection lost", __FUNCTION__);
  _mqttClient.stop();
  execCloudEventCallback(ArduinoIoTCloudEvent::DISCONNECT);
  return State::ConnectPhy;
}

void ArduinoIoTCloudTCP::onMessage(int length)
{
  ArduinoCloud.handleMessage(length);
}

void ArduinoIoTCloudTCP::handleMessage(int length)
{
  String topic = _mqttClient.messageTopic();

  byte bytes[length];

  for (int i = 0; i < length; i++) {
    bytes[i] = _mqttClient.read();
  }

  /* Topic for OTA properties and device configuration */
  if (_deviceTopicIn == topic) {
    CBORDecoder::decode(_device_property_container, (uint8_t*)bytes, length);
    _last_device_subscribe_cnt = 0;
    _next_device_subscribe_attempt_tick = 0;
  }

  /* Topic for user input data */
  if (_dataTopicIn == topic) {
    CBORDecoder::decode(_thing_property_container, (uint8_t*)bytes, length);
  }

  /* Topic for sync Thing last values on connect */
  if ((_shadowTopicIn == topic) && (_state == State::RequestLastValues))
  {
    DEBUG_VERBOSE("ArduinoIoTCloudTCP::%s [%d] last values received", __FUNCTION__, millis());
    CBORDecoder::decode(_thing_property_container, (uint8_t*)bytes, length, true);
    _time_service.setTimeZoneData(_tz_offset, _tz_dst_until);
    execCloudEventCallback(ArduinoIoTCloudEvent::SYNC);
    _last_sync_request_cnt = 0;
    _last_sync_request_tick = 0;
    _state = State::Connected;
  }
}

void ArduinoIoTCloudTCP::sendPropertyContainerToCloud(String const topic, PropertyContainer & property_container, unsigned int & current_property_index)
{
  int bytes_encoded = 0;
  uint8_t data[MQTT_TRANSMIT_BUFFER_SIZE];

  if (CBOREncoder::encode(property_container, data, sizeof(data), bytes_encoded, current_property_index, false) == CborNoError)
    if (bytes_encoded > 0)
    {
      /* If properties have been encoded store them in the back-up buffer
       * in order to allow retransmission in case of failure.
       */
      _mqtt_data_len = bytes_encoded;
      memcpy(_mqtt_data_buf, data, _mqtt_data_len);
      /* Transmit the properties to the MQTT broker */
      write(topic, _mqtt_data_buf, _mqtt_data_len);
    }
}

void ArduinoIoTCloudTCP::sendThingPropertiesToCloud()
{
  sendPropertyContainerToCloud(_dataTopicOut, _thing_property_container, _last_checked_property_index);
}

void ArduinoIoTCloudTCP::sendDevicePropertiesToCloud()
{
  PropertyContainer ro_device_property_container;
  unsigned int last_device_property_index = 0;

  std::list<String> ro_device_property_list {"LIB_VERSION", "OTA_CAP", "OTA_ERROR", "OTA_SHA256"};
  std::for_each(ro_device_property_list.begin(),
                ro_device_property_list.end(),
                [this, &ro_device_property_container ] (String const & name)
                {
                  Property* p = getProperty(this->_device_property_container, name);
                  if(p != nullptr)
                    addPropertyToContainer(ro_device_property_container, *p, p->name(), p->isWriteableByCloud() ? Permission::ReadWrite : Permission::Read);
                }
                );

  sendPropertyContainerToCloud(_deviceTopicOut, ro_device_property_container, last_device_property_index);
}

#if OTA_ENABLED
void ArduinoIoTCloudTCP::sendDevicePropertyToCloud(String const name)
{
  PropertyContainer temp_device_property_container;
  unsigned int last_device_property_index = 0;

  Property* p = getProperty(this->_device_property_container, name);
  if(p != nullptr)
  {
    addPropertyToContainer(temp_device_property_container, *p, p->name(), p->isWriteableByCloud() ? Permission::ReadWrite : Permission::Read);
    sendPropertyContainerToCloud(_deviceTopicOut, temp_device_property_container, last_device_property_index);
  }
}
#endif

void ArduinoIoTCloudTCP::requestLastValue()
{
  // Send the getLastValues CBOR message to the cloud
  // [{0: "r:m", 3: "getLastValues"}] = 81 A2 00 63 72 3A 6D 03 6D 67 65 74 4C 61 73 74 56 61 6C 75 65 73
  // Use http://cbor.me to easily generate CBOR encoding
  const uint8_t CBOR_REQUEST_LAST_VALUE_MSG[] = { 0x81, 0xA2, 0x00, 0x63, 0x72, 0x3A, 0x6D, 0x03, 0x6D, 0x67, 0x65, 0x74, 0x4C, 0x61, 0x73, 0x74, 0x56, 0x61, 0x6C, 0x75, 0x65, 0x73 };
  write(_shadowTopicOut, CBOR_REQUEST_LAST_VALUE_MSG, sizeof(CBOR_REQUEST_LAST_VALUE_MSG));
}

int ArduinoIoTCloudTCP::write(String const topic, byte const data[], int const length)
{
  if (_mqttClient.beginMessage(topic, length, false, 0)) {
    if (_mqttClient.write(data, length)) {
      if (_mqttClient.endMessage()) {
        return 1;
      }
    }
  }
  return 0;
}

#if OTA_ENABLED
void ArduinoIoTCloudTCP::onOTARequest()
{
  DEBUG_INFO("ArduinoIoTCloudTCP::%s _ota_url = %s", __FUNCTION__, _ota_url.c_str());

#ifdef ARDUINO_ARCH_SAMD
  _ota_error = samd_onOTARequest(_ota_url.c_str());
#endif

#ifdef ARDUINO_NANO_RP2040_CONNECT
  _ota_error = rp2040_connect_onOTARequest(_ota_url.c_str());
#endif

#if defined(ARDUINO_PORTENTA_H7_M7) || defined(ARDUINO_PORTENTA_H7_M4)
  _ota_error = portenta_h7_onOTARequest(_ota_url.c_str());
#endif
}
#endif

void ArduinoIoTCloudTCP::updateThingTopics()
{
  _shadowTopicOut = getTopic_shadowout();
  _shadowTopicIn  = getTopic_shadowin();
  _dataTopicOut   = getTopic_dataout();
  _dataTopicIn    = getTopic_datain();

  clrThingIdOutdatedFlag();
}

/******************************************************************************
 * EXTERN DEFINITION
 ******************************************************************************/

ArduinoIoTCloudTCP ArduinoCloud;

#endif