bool IsValidNetId(LoRaPayloadData loRaPayload)
{
// Check if the current dev addr is in our network id
byte devAddrNwkid = loRaPayload.GetDevAddrNetID();
var netIdBytes = BitConverter.GetBytes(this.configuration.NetId);
devAddrNwkid = (byte)(devAddrNwkid >> 1);
if (devAddrNwkid == (netIdBytes[0] & 0b01111111))
{
return(true);
}
// If not, check if the devaddr is part of the allowed dev address list
var currentDevAddr = ConversionHelper.ByteArrayToString(loRaPayload.DevAddr);
if (this.configuration.AllowedDevAddresses != null && this.configuration.AllowedDevAddresses.Contains(currentDevAddr))
{
return(true);
}
return(false);
}
/// <summary>
/// Process LoRa message where the payload is of type LoRaPayloadData
/// </summary>
async Task <DownlinkPktFwdMessage> ProcessDataMessageAsync(LoRaTools.LoRaPhysical.Rxpk rxpk, LoRaPayloadData loraPayload, DateTime startTime)
{
var devAddr = loraPayload.DevAddr;
var timeWatcher = new LoRaOperationTimeWatcher(this.loraRegion, startTime);
using (var processLogger = new ProcessLogger(timeWatcher, devAddr))
{
if (!this.IsValidNetId(loraPayload.GetDevAddrNetID(), this.configuration.NetId))
{
Logger.Log(ConversionHelper.ByteArrayToString(devAddr), "device is using another network id, ignoring this message", LogLevel.Debug);
processLogger.LogLevel = LogLevel.Debug;
return(null);
}
// Find device that matches:
// - devAddr
// - mic check (requires: loraDeviceInfo.NwkSKey or loraDeviceInfo.AppKey, rxpk.LoraPayload.Mic)
// - gateway id
var loRaDevice = await this.deviceRegistry.GetDeviceForPayloadAsync(loraPayload);
if (loRaDevice == null)
{
Logger.Log(ConversionHelper.ByteArrayToString(devAddr), $"device is not from our network, ignoring message", LogLevel.Information);
return(null);
}
// Add context to logger
processLogger.SetDevEUI(loRaDevice.DevEUI);
var isMultiGateway = !string.Equals(loRaDevice.GatewayID, this.configuration.GatewayID, StringComparison.InvariantCultureIgnoreCase);
var frameCounterStrategy = isMultiGateway ? this.frameCounterUpdateStrategyFactory.GetMultiGatewayStrategy() : this.frameCounterUpdateStrategyFactory.GetSingleGatewayStrategy();
var payloadFcnt = loraPayload.GetFcnt();
var requiresConfirmation = loraPayload.IsConfirmed();
using (new LoRaDeviceFrameCounterSession(loRaDevice, frameCounterStrategy))
{
// Leaf devices that restart lose the counter. In relax mode we accept the incoming frame counter
// ABP device does not reset the Fcnt so in relax mode we should reset for 0 (LMIC based) or 1
var isFrameCounterFromNewlyStartedDevice = false;
if (payloadFcnt <= 1)
{
if (loRaDevice.IsABP)
{
if (loRaDevice.IsABPRelaxedFrameCounter && loRaDevice.FCntUp >= 0 && payloadFcnt <= 1)
{
// known problem when device restarts, starts fcnt from zero
_ = frameCounterStrategy.ResetAsync(loRaDevice);
isFrameCounterFromNewlyStartedDevice = true;
}
}
else if (loRaDevice.FCntUp == payloadFcnt && payloadFcnt == 0)
{
// Some devices start with frame count 0
isFrameCounterFromNewlyStartedDevice = true;
}
}
// Reply attack or confirmed reply
// Confirmed resubmit: A confirmed message that was received previously but we did not answer in time
// Device will send it again and we just need to return an ack (but also check for C2D to send it over)
var isConfirmedResubmit = false;
if (!isFrameCounterFromNewlyStartedDevice && payloadFcnt <= loRaDevice.FCntUp)
{
// if it is confirmed most probably we did not ack in time before or device lost the ack packet so we should continue but not send the msg to iothub
if (requiresConfirmation && payloadFcnt == loRaDevice.FCntUp)
{
if (!loRaDevice.ValidateConfirmResubmit(payloadFcnt))
{
Logger.Log(loRaDevice.DevEUI, $"resubmit from confirmed message exceeds threshold of {LoRaDevice.MaxConfirmationResubmitCount}, message ignored, msg: {payloadFcnt} server: {loRaDevice.FCntUp}", LogLevel.Debug);
processLogger.LogLevel = LogLevel.Debug;
return(null);
}
isConfirmedResubmit = true;
Logger.Log(loRaDevice.DevEUI, $"resubmit from confirmed message detected, msg: {payloadFcnt} server: {loRaDevice.FCntUp}", LogLevel.Information);
}
else
{
Logger.Log(loRaDevice.DevEUI, $"invalid frame counter, message ignored, msg: {payloadFcnt} server: {loRaDevice.FCntUp}", LogLevel.Information);
return(null);
}
}
var fcntDown = 0;
// If it is confirmed it require us to update the frame counter down
// Multiple gateways: in redis, otherwise in device twin
if (requiresConfirmation)
{
fcntDown = await frameCounterStrategy.NextFcntDown(loRaDevice, payloadFcnt);
// Failed to update the fcnt down
// In multi gateway scenarios it means the another gateway was faster than using, can stop now
if (fcntDown <= 0)
{
// update our fcntup anyway?
// loRaDevice.SetFcntUp(payloadFcnt);
Logger.Log(loRaDevice.DevEUI, "another gateway has already sent ack or downlink msg", LogLevel.Information);
return(null);
}
Logger.Log(loRaDevice.DevEUI, $"down frame counter: {loRaDevice.FCntDown}", LogLevel.Information);
}
if (!isConfirmedResubmit)
{
var validFcntUp = isFrameCounterFromNewlyStartedDevice || (payloadFcnt > loRaDevice.FCntUp);
if (validFcntUp)
{
Logger.Log(loRaDevice.DevEUI, $"valid frame counter, msg: {payloadFcnt} server: {loRaDevice.FCntUp}", LogLevel.Information);
object payloadData = null;
// if it is an upward acknowledgement from the device it does not have a payload
// This is confirmation from leaf device that he received a C2D confirmed
// if a message payload is null we don't try to decrypt it.
if (loraPayload.Frmpayload.Length != 0)
{
byte[] decryptedPayloadData = null;
try
{
decryptedPayloadData = loraPayload.GetDecryptedPayload(loRaDevice.AppSKey);
}
catch (Exception ex)
{
Logger.Log(loRaDevice.DevEUI, $"failed to decrypt message: {ex.Message}", LogLevel.Error);
}
var fportUp = loraPayload.GetFPort();
if (string.IsNullOrEmpty(loRaDevice.SensorDecoder))
{
Logger.Log(loRaDevice.DevEUI, $"no decoder set in device twin. port: {fportUp}", LogLevel.Debug);
payloadData = Convert.ToBase64String(decryptedPayloadData);
}
else
{
Logger.Log(loRaDevice.DevEUI, $"decoding with: {loRaDevice.SensorDecoder} port: {fportUp}", LogLevel.Debug);
payloadData = await this.payloadDecoder.DecodeMessageAsync(decryptedPayloadData, fportUp, loRaDevice.SensorDecoder);
}
}
if (!await this.SendDeviceEventAsync(loRaDevice, rxpk, payloadData, loraPayload, timeWatcher))
{
// failed to send event to IoT Hub, stop now
return(null);
}
loRaDevice.SetFcntUp(payloadFcnt);
}
else
{
Logger.Log(loRaDevice.DevEUI, $"invalid frame counter, msg: {payloadFcnt} server: {loRaDevice.FCntUp}", LogLevel.Information);
}
}
// We check if we have time to futher progress or not
// C2D checks are quite expensive so if we are really late we just stop here
var timeToSecondWindow = timeWatcher.GetRemainingTimeToReceiveSecondWindow(loRaDevice);
if (timeToSecondWindow < LoRaOperationTimeWatcher.ExpectedTimeToPackageAndSendMessage)
{
if (requiresConfirmation)
{
Logger.Log(loRaDevice.DevEUI, $"too late for down message ({timeWatcher.GetElapsedTime()}), sending only ACK to gateway", LogLevel.Information);
}
return(null);
}
// If it is confirmed and
// - Downlink is disabled for the device or
// - we don't have time to check c2d and send to device we return now
if (requiresConfirmation && (!loRaDevice.DownlinkEnabled || timeToSecondWindow.Subtract(LoRaOperationTimeWatcher.ExpectedTimeToPackageAndSendMessage) <= LoRaOperationTimeWatcher.MinimumAvailableTimeToCheckForCloudMessage))
{
return(this.CreateDownlinkMessage(
null,
loRaDevice,
rxpk,
loraPayload,
timeWatcher,
devAddr,
false, // fpending
(ushort)fcntDown));
}
// Flag indicating if there is another C2D message waiting
var fpending = false;
// Contains the Cloud to message we need to send
Message cloudToDeviceMessage = null;
if (loRaDevice.DownlinkEnabled)
{
// ReceiveAsync has a longer timeout
// But we wait less that the timeout (available time before 2nd window)
// if message is received after timeout, keep it in loraDeviceInfo and return the next call
var timeAvailableToCheckCloudToDeviceMessages = timeWatcher.GetAvailableTimeToCheckCloudToDeviceMessage(loRaDevice);
if (timeAvailableToCheckCloudToDeviceMessages >= LoRaOperationTimeWatcher.MinimumAvailableTimeToCheckForCloudMessage)
{
cloudToDeviceMessage = await loRaDevice.ReceiveCloudToDeviceAsync(timeAvailableToCheckCloudToDeviceMessages);
if (cloudToDeviceMessage != null && !this.ValidateCloudToDeviceMessage(loRaDevice, cloudToDeviceMessage))
{
_ = loRaDevice.CompleteCloudToDeviceMessageAsync(cloudToDeviceMessage);
cloudToDeviceMessage = null;
}
if (cloudToDeviceMessage != null)
{
if (!requiresConfirmation)
{
// The message coming from the device was not confirmed, therefore we did not computed the frame count down
// Now we need to increment because there is a C2D message to be sent
fcntDown = await frameCounterStrategy.NextFcntDown(loRaDevice, payloadFcnt);
if (fcntDown == 0)
{
// We did not get a valid frame count down, therefore we should not process the message
_ = loRaDevice.AbandonCloudToDeviceMessageAsync(cloudToDeviceMessage);
cloudToDeviceMessage = null;
}
else
{
requiresConfirmation = true;
}
Logger.Log(loRaDevice.DevEUI, $"down frame counter: {loRaDevice.FCntDown}", LogLevel.Information);
}
// Checking again if cloudToDeviceMessage is valid because the fcntDown resolution could have failed,
// causing us to drop the message
if (cloudToDeviceMessage != null)
{
var remainingTimeForFPendingCheck = timeWatcher.GetRemainingTimeToReceiveSecondWindow(loRaDevice) - (LoRaOperationTimeWatcher.CheckForCloudMessageCallEstimatedOverhead + LoRaOperationTimeWatcher.MinimumAvailableTimeToCheckForCloudMessage);
if (remainingTimeForFPendingCheck >= LoRaOperationTimeWatcher.MinimumAvailableTimeToCheckForCloudMessage)
{
var additionalMsg = await loRaDevice.ReceiveCloudToDeviceAsync(LoRaOperationTimeWatcher.MinimumAvailableTimeToCheckForCloudMessage);
if (additionalMsg != null)
{
fpending = true;
_ = loRaDevice.AbandonCloudToDeviceMessageAsync(additionalMsg);
Logger.Log(loRaDevice.DevEUI, $"found fpending c2d message id: {additionalMsg.MessageId ?? "undefined"}", LogLevel.Information);
}
}
}
}
}
}
// No C2D message and request was not confirmed, return nothing
if (!requiresConfirmation)
{
return(null);
}
var confirmDownstream = this.CreateDownlinkMessage(
cloudToDeviceMessage,
loRaDevice,
rxpk,
loraPayload,
timeWatcher,
devAddr,
fpending,
(ushort)fcntDown);
if (cloudToDeviceMessage != null)
{
if (confirmDownstream == null)
{
Logger.Log(loRaDevice.DevEUI, $"out of time for downstream message, will abandon c2d message id: {cloudToDeviceMessage.MessageId ?? "undefined"}", LogLevel.Information);
_ = loRaDevice.AbandonCloudToDeviceMessageAsync(cloudToDeviceMessage);
}
else
{
_ = loRaDevice.CompleteCloudToDeviceMessageAsync(cloudToDeviceMessage);
}
}
return(confirmDownstream);
}
}
}