⚡go-lnd-router-events

This module allows subscribers to get notified about HTLC SettleEvents and InvoiceEvents. A subscripiton to HTLC events retrieve the following statistics from its related preceeding ForwardEvent:

* FromPubKey   
* FromAlias    
* IncomingMSats
* ToAlias      
* ToPubKey     
* OutgoingMSats
* ChanId_In    
* ChanId_Out   
* HtlcId_In    
* HtlcId_Out   

A subscripiton to invoice events retrieves the invoice related fields:

* IsSettled
* SettleAmount_msat
* Preimage

Installation

go get github.com/hieblmi/go-lnd-router-events

How it works

LND's router RPC interface allows to listen to ForwardEvents that basically represent an attempt from an initiating peer on a route to push a payment through our node. The successful forward events can be obtained by clients who implement

type Observer interface {   
    Update(event *Event)
    GetName() string    
}

and register their observer, in this case for forward settlements:

listener := events.New(&events.Config{
         MacaroonPath: config.MacaroonPath,
         CertPath:     config.CertPath,
         RpcHost:      config.RpcHost,
 })
 listener.Register(&LndEventObserver{
         Name:     "YourObserverName",                 
 }, events.Forward)
 listener.Start()

The update method then receives successful forward events:

func (o *yourObserver) Update(e *events.Event) {
 fmt.Println(e.Type)
 fmt.Println(e.IncomingMSats)
 fmt.Println(e.OutgoingMSats)
}

Little more detail

To retrieve the details of a successful payment we have to match the SettleEvent's ids to the ids of the preceeding ForwardEvent. In this instance this is solved by keeping a map of [key|ForwardEvent] and retrieve a given forward attempt when the respective SettleEvent occurs. The key is calculated by

IncomingChannelId + OutgoingChannelId + IncomingHtlcId + OutgoingHtlcId

In case the payment through our node isn't successful we will observe a ForwardFailEvent or LinkFailEvent. In these cases we simply remove the respective ForwardEvent from our map.

Disclaimer

This stuff is experimental so do use it with care. I am highly appreciative of feedback and ways to improve my understanding of everything Lightning.

If you like what you see you could send me a tip :-)

Download a LightningAddress enabled wallet like Blixt or BlueWallet and tip to: ⚡tips@allmysats.com