private static bool ValidateRequest(LoRaRequest request, bool isFrameCounterFromNewlyStartedDevice, uint payloadFcnt, LoRaDevice loRaDevice, bool requiresConfirmation, out bool isConfirmedResubmit, out LoRaDeviceRequestProcessResult result)
{
isConfirmedResubmit = false;
result = null;
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.Error);
result = new LoRaDeviceRequestProcessResult(loRaDevice, request, LoRaDeviceRequestFailedReason.ConfirmationResubmitThresholdExceeded);
return(false);
}
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.Debug);
result = new LoRaDeviceRequestProcessResult(loRaDevice, request, LoRaDeviceRequestFailedReason.InvalidFrameCounter);
return(false);
}
}
// ensuring the framecount difference between the node and the server
// is <= MAX_FCNT_GAP
var diff = payloadFcnt > loRaDevice.FCntUp ? payloadFcnt - loRaDevice.FCntUp : loRaDevice.FCntUp - payloadFcnt;
var valid = diff <= Constants.MAX_FCNT_GAP;
if (!valid)
{
Logger.Log(loRaDevice.DevEUI, $"invalid frame counter (diverges too much), message ignored, msg: {payloadFcnt} server: {loRaDevice.FCntUp}", LogLevel.Error);
result = new LoRaDeviceRequestProcessResult(loRaDevice, request, LoRaDeviceRequestFailedReason.InvalidFrameCounter);
}
return(valid);
}
