move nexthop logic inside the interceptor

cln/cln_client.go

@@ -65,7 +65,7 @@ func (c *ClnClient) IsConnected(destination []byte) (bool, error) {
 	}
 
 	for _, peer := range peers {
-		if pubKey == peer.Id {
+		if pubKey == peer.Id && peer.Connected {
 			log.Printf("destination online: %x", destination)
 			return true, nil
 		}
@@ -228,3 +228,29 @@ func (c *ClnClient) GetClosedChannels(nodeID string, channelPoints map[string]ui
 
 	return r, nil
 }
+
+func (c *ClnClient) GetPeerId(scid *basetypes.ShortChannelID) ([]byte, error) {
+	scidStr := scid.ToString()
+	peers, err := c.client.ListPeers()
+	if err != nil {
+		return nil, err
+	}
+
+	var dest *string
+	for _, p := range peers {
+		for _, ch := range p.Channels {
+			if ch.Alias.Local == scidStr ||
+				ch.Alias.Remote == scidStr ||
+				ch.ShortChannelId == scidStr {
+				dest = &p.Id
+				break
+			}
+		}
+	}
+
+	if dest == nil {
+		return nil, nil
+	}
+
+	return hex.DecodeString(*dest)
+}

cln/cln_interceptor.go

@@ -10,6 +10,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/breez/lspd/basetypes"
 	"github.com/breez/lspd/cln_plugin/proto"
 	"github.com/breez/lspd/config"
 	"github.com/breez/lspd/interceptor"
@@ -129,20 +130,6 @@ func (i *ClnHtlcInterceptor) intercept() error {
 				log.Printf("unexpected error in interceptor.Recv() %v", err)
 				break
 			}
-			nextHop := "<unknown>"
-			channels, err := i.client.client.GetChannel(request.Onion.ShortChannelId)
-			if err != nil {
-				for _, c := range channels {
-					if c.Source == i.config.NodePubkey {
-						nextHop = c.Destination
-						break
-					}
-					if c.Destination == i.config.NodePubkey {
-						nextHop = c.Source
-						break
-					}
-				}
-			}
 
 			i.doneWg.Add(1)
 			go func() {
@@ -150,8 +137,17 @@ func (i *ClnHtlcInterceptor) intercept() error {
 				if err != nil {
 					interceptorClient.Send(i.defaultResolution(request))
 					i.doneWg.Done()
+					return
 				}
-				interceptResult := i.interceptor.Intercept(nextHop, paymentHash, request.Onion.ForwardMsat, request.Onion.OutgoingCltvValue, request.Htlc.CltvExpiry)
+
+				scid, err := basetypes.NewShortChannelIDFromString(request.Onion.ShortChannelId)
+				if err != nil {
+					interceptorClient.Send(i.defaultResolution(request))
+					i.doneWg.Done()
+					return
+				}
+
+				interceptResult := i.interceptor.Intercept(scid, paymentHash, request.Onion.ForwardMsat, request.Onion.OutgoingCltvValue, request.Htlc.CltvExpiry)
 				switch interceptResult.Action {
 				case interceptor.INTERCEPT_RESUME_WITH_ONION:
 					interceptorClient.Send(i.resumeWithOnion(request, interceptResult))

interceptor/intercept.go

@@ -73,7 +73,7 @@ func NewInterceptor(
 	}
 }
 
-func (i *Interceptor) Intercept(nextHop string, reqPaymentHash []byte, reqOutgoingAmountMsat uint64, reqOutgoingExpiry uint32, reqIncomingExpiry uint32) InterceptResult {
+func (i *Interceptor) Intercept(scid *basetypes.ShortChannelID, reqPaymentHash []byte, reqOutgoingAmountMsat uint64, reqOutgoingExpiry uint32, reqIncomingExpiry uint32) InterceptResult {
 	reqPaymentHashStr := hex.EncodeToString(reqPaymentHash)
 	resp, _, _ := i.payHashGroup.Do(reqPaymentHashStr, func() (interface{}, error) {
 		token, params, paymentHash, paymentSecret, destination, incomingAmountMsat, outgoingAmountMsat, channelPoint, tag, err := i.store.PaymentInfo(reqPaymentHash)
@@ -85,7 +85,24 @@ func (i *Interceptor) Intercept(nextHop string, reqPaymentHash []byte, reqOutgoi
 			}, nil
 		}
 
-		if paymentSecret == nil || (nextHop != "<unknown>" && nextHop != hex.EncodeToString(destination)) {
+		nextHop, err := i.client.GetPeerId(scid)
+		if err != nil {
+			log.Printf("GetPeerId(%s) error: %v", scid.ToString(), err)
+			return InterceptResult{
+				Action:      INTERCEPT_FAIL_HTLC_WITH_CODE,
+				FailureCode: FAILURE_TEMPORARY_NODE_FAILURE,
+			}, nil
+		}
+
+		// If the payment was registered, but the next hop is not the destination
+		// that means we are not the last hop of the payment, so we'll just forward.
+		if destination != nil && nextHop != nil && !bytes.Equal(nextHop, destination) {
+			return InterceptResult{
+				Action: INTERCEPT_RESUME,
+			}, nil
+		}
+
+		if paymentSecret == nil {
 			return InterceptResult{
 				Action: INTERCEPT_RESUME,
 			}, nil

lightning/client.go

@@ -31,6 +31,7 @@ type Client interface {
 	IsConnected(destination []byte) (bool, error)
 	OpenChannel(req *OpenChannelRequest) (*wire.OutPoint, error)
 	GetChannel(peerID []byte, channelPoint wire.OutPoint) (*GetChannelResult, error)
+	GetPeerId(scid *basetypes.ShortChannelID) ([]byte, error)
 	GetNodeChannelCount(nodeID []byte) (int, error)
 	GetClosedChannels(nodeID string, channelPoints map[string]uint64) (map[string]uint64, error)
 }

lnd/client.go

@@ -79,18 +79,18 @@ func (c *LndClient) GetInfo() (*lightning.GetInfoResult, error) {
 }
 
 func (c *LndClient) IsConnected(destination []byte) (bool, error) {
-	pubKey := hex.EncodeToString(destination)
+	pubkey := hex.EncodeToString(destination)
 
-	r, err := c.client.ListPeers(context.Background(), &lnrpc.ListPeersRequest{LatestError: true})
+	r, err := c.client.GetPeerConnected(context.Background(), &lnrpc.GetPeerConnectedRequest{
+		Pubkey: pubkey,
+	})
 	if err != nil {
-		log.Printf("LND: client.ListPeers() error: %v", err)
+		log.Printf("LND: client.GetPeerConnected() error: %v", err)
-		return false, fmt.Errorf("LND: client.ListPeers() error: %w", err)
+		return false, fmt.Errorf("LND: client.GetPeerConnected() error: %w", err)
 	}
-	for _, peer := range r.Peers {
+	if r.Connected {
-		if pubKey == peer.PubKey {
+		log.Printf("LND: destination online: %x", destination)
-			log.Printf("destination online: %x", destination)
+		return true, nil
-			return true, nil
-		}
 	}
 
 	log.Printf("LND: destination offline: %x", destination)
@@ -230,3 +230,20 @@ func (c *LndClient) getWaitingCloseChannels(nodeID string) ([]*lnrpc.PendingChan
 	}
 	return waitingCloseChannels, nil
 }
+
+func (c *LndClient) GetPeerId(scid *basetypes.ShortChannelID) ([]byte, error) {
+	scidu64 := uint64(*scid)
+	peer, err := c.client.GetPeerIdByScid(context.Background(), &lnrpc.GetPeerIdByScidRequest{
+		Scid: scidu64,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	if peer.PeerId == "" {
+		return nil, nil
+	}
+
+	peerid, _ := hex.DecodeString(peer.PeerId)
+	return peerid, nil
+}

lnd/interceptor.go

@@ -6,6 +6,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/breez/lspd/basetypes"
 	"github.com/breez/lspd/config"
 	"github.com/breez/lspd/interceptor"
 	"github.com/lightningnetwork/lnd/lnrpc"
@@ -126,20 +127,10 @@ func (i *LndHtlcInterceptor) intercept() error {
 				break
 			}
 
-			nextHop := "<unknown>"
-			chanInfo, err := i.client.client.GetChanInfo(context.Background(), &lnrpc.ChanInfoRequest{ChanId: request.OutgoingRequestedChanId})
-			if err == nil && chanInfo != nil {
-				if chanInfo.Node1Pub == i.config.NodePubkey {
-					nextHop = chanInfo.Node2Pub
-				}
-				if chanInfo.Node2Pub == i.config.NodePubkey {
-					nextHop = chanInfo.Node1Pub
-				}
-			}
-
 			i.doneWg.Add(1)
 			go func() {
-				interceptResult := i.interceptor.Intercept(nextHop, request.PaymentHash, request.OutgoingAmountMsat, request.OutgoingExpiry, request.IncomingExpiry)
+				scid := basetypes.ShortChannelID(request.OutgoingRequestedChanId)
+				interceptResult := i.interceptor.Intercept(&scid, request.PaymentHash, request.OutgoingAmountMsat, request.OutgoingExpiry, request.IncomingExpiry)
 				switch interceptResult.Action {
 				case interceptor.INTERCEPT_RESUME_WITH_ONION:
 					interceptorClient.Send(&routerrpc.ForwardHtlcInterceptResponse{