func (n *networkServer) HandleDownlink(message *pb_broker.DownlinkMessage) (*pb_broker.DownlinkMessage, error) {
// Get Device
dev, err := n.devices.Get(*message.AppEui, *message.DevEui)
if err != nil {
return nil, err
}
n.status.downlink.Mark(1)
dev.StartUpdate()
if dev.AppID != message.AppId || dev.DevID != message.DevId {
return nil, errors.NewErrInvalidArgument("Downlink", "AppID and DevID do not match AppEUI and DevEUI")
}
// Unmarshal LoRaWAN Payload
var phyPayload lorawan.PHYPayload
err = phyPayload.UnmarshalBinary(message.Payload)
if err != nil {
return nil, err
}
macPayload, ok := phyPayload.MACPayload.(*lorawan.MACPayload)
if !ok {
return nil, errors.NewErrInvalidArgument("Downlink", "does not contain a MAC payload")
}
// Set DevAddr
macPayload.FHDR.DevAddr = lorawan.DevAddr(dev.DevAddr)
// FIRST set and THEN increment FCntDown
// TODO: For confirmed downlink, FCntDown should be incremented AFTER ACK
macPayload.FHDR.FCnt = dev.FCntDown
dev.FCntDown++
err = n.devices.Set(dev)
if err != nil {
return nil, err
}
// Sign MIC
phyPayload.SetMIC(lorawan.AES128Key(dev.NwkSKey))
// Update message
bytes, err := phyPayload.MarshalBinary()
if err != nil {
return nil, err
}
message.Payload = bytes
return message, nil
}
func (h *handler) ConvertToLoRaWAN(ctx log.Interface, appDown *types.DownlinkMessage, ttnDown *pb_broker.DownlinkMessage) error {
// Find Device
dev, err := h.devices.Get(appDown.AppID, appDown.DevID)
if err != nil {
return err
}
// LoRaWAN: Unmarshal Downlink
var phyPayload lorawan.PHYPayload
err = phyPayload.UnmarshalBinary(ttnDown.Payload)
if err != nil {
return err
}
macPayload, ok := phyPayload.MACPayload.(*lorawan.MACPayload)
if !ok {
return errors.NewErrInvalidArgument("Downlink", "does not contain a MAC payload")
}
if ttnDown.DownlinkOption != nil && ttnDown.DownlinkOption.ProtocolConfig.GetLorawan() != nil {
macPayload.FHDR.FCnt = ttnDown.DownlinkOption.ProtocolConfig.GetLorawan().FCnt
}
// Abort when downlink not needed
if len(appDown.PayloadRaw) == 0 && !macPayload.FHDR.FCtrl.ACK && len(macPayload.FHDR.FOpts) == 0 {
return ErrNotNeeded
}
// Set FPort
if appDown.FPort != 0 {
macPayload.FPort = &appDown.FPort
}
// Set Payload
if len(appDown.PayloadRaw) > 0 {
macPayload.FRMPayload = []lorawan.Payload{&lorawan.DataPayload{Bytes: appDown.PayloadRaw}}
if macPayload.FPort == nil || *macPayload.FPort == 0 {
macPayload.FPort = pointer.Uint8(1)
}
} else {
macPayload.FRMPayload = []lorawan.Payload{}
}
// Encrypt
err = phyPayload.EncryptFRMPayload(lorawan.AES128Key(dev.AppSKey))
if err != nil {
return err
}
// Set MIC
err = phyPayload.SetMIC(lorawan.AES128Key(dev.NwkSKey))
if err != nil {
return err
}
// Marshal
phyPayloadBytes, err := phyPayload.MarshalBinary()
if err != nil {
return err
}
ttnDown.Payload = phyPayloadBytes
return nil
}