move lnd specific onion creation to lnd

breez · Jun 30, 2023 · 34646d5 · 34646d5
1 parent c37a745
commit 34646d5
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Showing 2 changed files with 100 additions and 97 deletions.
diff --git a/interceptor/intercept.go b/interceptor/intercept.go
@@ -14,12 +14,7 @@ import (
 	"github.com/breez/lspd/config"
 	"github.com/breez/lspd/lightning"
 	"github.com/breez/lspd/notifications"
-	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/wire"
-	sphinx "github.com/lightningnetwork/lightning-onion"
-	"github.com/lightningnetwork/lnd/lnwire"
-	"github.com/lightningnetwork/lnd/record"
-	"github.com/lightningnetwork/lnd/routing/route"
 	"golang.org/x/sync/singleflight"
 )
 
@@ -40,13 +35,14 @@ var (
 )
 
 type InterceptResult struct {
-	Action       InterceptAction
-	FailureCode  InterceptFailureCode
-	Destination  []byte
-	AmountMsat   uint64
-	ChannelPoint *wire.OutPoint
-	ChannelId    uint64
-	OnionBlob    []byte
+	Action          InterceptAction
+	FailureCode     InterceptFailureCode
+	Destination     []byte
+	AmountMsat      uint64
+	TotalAmountMsat uint64
+	ChannelPoint    *wire.OutPoint
+	ChannelId       uint64
+	PaymentSecret   []byte
 }
 
 type Interceptor struct {
@@ -230,81 +226,9 @@ func (i *Interceptor) Intercept(scid *basetypes.ShortChannelID, reqPaymentHash [
 			}
 		}
 
-		pubKey, err := btcec.ParsePubKey(destination)
-		if err != nil {
-			log.Printf("btcec.ParsePubKey(%x): %v", destination, err)
-			return InterceptResult{
-				Action:      INTERCEPT_FAIL_HTLC_WITH_CODE,
-				FailureCode: FAILURE_TEMPORARY_CHANNEL_FAILURE,
-			}, nil
-		}
-
-		sessionKey, err := btcec.NewPrivateKey()
-		if err != nil {
-			log.Printf("btcec.NewPrivateKey(): %v", err)
-			return InterceptResult{
-				Action:      INTERCEPT_FAIL_HTLC_WITH_CODE,
-				FailureCode: FAILURE_TEMPORARY_CHANNEL_FAILURE,
-			}, nil
-		}
-
 		var bigProd, bigAmt big.Int
 		amt := (bigAmt.Div(bigProd.Mul(big.NewInt(outgoingAmountMsat), big.NewInt(int64(reqOutgoingAmountMsat))), big.NewInt(incomingAmountMsat))).Int64()
 
-		var addr [32]byte
-		copy(addr[:], paymentSecret)
-		hop := route.Hop{
-			AmtToForward:     lnwire.MilliSatoshi(amt),
-			OutgoingTimeLock: reqOutgoingExpiry,
-			MPP:              record.NewMPP(lnwire.MilliSatoshi(outgoingAmountMsat), addr),
-			CustomRecords:    make(record.CustomSet),
-		}
-
-		var b bytes.Buffer
-		err = hop.PackHopPayload(&b, uint64(0))
-		if err != nil {
-			log.Printf("hop.PackHopPayload(): %v", err)
-			return InterceptResult{
-				Action:      INTERCEPT_FAIL_HTLC_WITH_CODE,
-				FailureCode: FAILURE_TEMPORARY_CHANNEL_FAILURE,
-			}, nil
-		}
-
-		payload, err := sphinx.NewHopPayload(nil, b.Bytes())
-		if err != nil {
-			log.Printf("sphinx.NewHopPayload(): %v", err)
-			return InterceptResult{
-				Action:      INTERCEPT_FAIL_HTLC_WITH_CODE,
-				FailureCode: FAILURE_TEMPORARY_CHANNEL_FAILURE,
-			}, nil
-		}
-
-		var sphinxPath sphinx.PaymentPath
-		sphinxPath[0] = sphinx.OnionHop{
-			NodePub:    *pubKey,
-			HopPayload: payload,
-		}
-		sphinxPacket, err := sphinx.NewOnionPacket(
-			&sphinxPath, sessionKey, reqPaymentHash,
-			sphinx.DeterministicPacketFiller,
-		)
-		if err != nil {
-			log.Printf("sphinx.NewOnionPacket(): %v", err)
-			return InterceptResult{
-				Action:      INTERCEPT_FAIL_HTLC_WITH_CODE,
-				FailureCode: FAILURE_TEMPORARY_CHANNEL_FAILURE,
-			}, nil
-		}
-		var onionBlob bytes.Buffer
-		err = sphinxPacket.Encode(&onionBlob)
-		if err != nil {
-			log.Printf("sphinxPacket.Encode(): %v", err)
-			return InterceptResult{
-				Action:      INTERCEPT_FAIL_HTLC_WITH_CODE,
-				FailureCode: FAILURE_TEMPORARY_CHANNEL_FAILURE,
-			}, nil
-		}
-
 		deadline := time.Now().Add(60 * time.Second)
 
 		for {
@@ -334,12 +258,13 @@ func (i *Interceptor) Intercept(scid *basetypes.ShortChannelID, reqPaymentHash [
 				}
 
 				return InterceptResult{
-					Action:       INTERCEPT_RESUME_WITH_ONION,
-					Destination:  destination,
-					ChannelPoint: channelPoint,
-					ChannelId:    channelID,
-					AmountMsat:   uint64(amt),
-					OnionBlob:    onionBlob.Bytes(),
+					Action:          INTERCEPT_RESUME_WITH_ONION,
+					Destination:     destination,
+					ChannelPoint:    channelPoint,
+					ChannelId:       channelID,
+					PaymentSecret:   paymentSecret,
+					AmountMsat:      uint64(amt),
+					TotalAmountMsat: uint64(outgoingAmountMsat),
 				}, nil
 			}
 

diff --git a/lnd/interceptor.go b/lnd/interceptor.go
@@ -1,6 +1,7 @@
 package lnd
 
 import (
+	"bytes"
 	"context"
 	"log"
 	"sync"
@@ -9,8 +10,13 @@ import (
 	"github.com/breez/lspd/basetypes"
 	"github.com/breez/lspd/config"
 	"github.com/breez/lspd/interceptor"
+	"github.com/btcsuite/btcd/btcec/v2"
+	sphinx "github.com/lightningnetwork/lightning-onion"
 	"github.com/lightningnetwork/lnd/lnrpc"
 	"github.com/lightningnetwork/lnd/lnrpc/routerrpc"
+	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/lightningnetwork/lnd/record"
+	"github.com/lightningnetwork/lnd/routing/route"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 )
@@ -133,13 +139,23 @@ func (i *LndHtlcInterceptor) intercept() error {
 				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{
-						IncomingCircuitKey:      request.IncomingCircuitKey,
-						Action:                  routerrpc.ResolveHoldForwardAction_RESUME,
-						OutgoingAmountMsat:      interceptResult.AmountMsat,
-						OutgoingRequestedChanId: uint64(interceptResult.ChannelId),
-						OnionBlob:               interceptResult.OnionBlob,
-					})
+					onion, err := i.constructOnion(interceptResult, request.OutgoingExpiry, request.PaymentHash)
+					if err == nil {
+						interceptorClient.Send(&routerrpc.ForwardHtlcInterceptResponse{
+							IncomingCircuitKey:      request.IncomingCircuitKey,
+							Action:                  routerrpc.ResolveHoldForwardAction_RESUME,
+							OutgoingAmountMsat:      interceptResult.AmountMsat,
+							OutgoingRequestedChanId: uint64(interceptResult.ChannelId),
+							OnionBlob:               onion,
+						})
+					} else {
+						interceptorClient.Send(&routerrpc.ForwardHtlcInterceptResponse{
+							IncomingCircuitKey: request.IncomingCircuitKey,
+							Action:             routerrpc.ResolveHoldForwardAction_FAIL,
+							FailureCode:        lnrpc.Failure_TEMPORARY_CHANNEL_FAILURE,
+						})
+					}
+
 				case interceptor.INTERCEPT_FAIL_HTLC_WITH_CODE:
 					interceptorClient.Send(&routerrpc.ForwardHtlcInterceptResponse{
 						IncomingCircuitKey: request.IncomingCircuitKey,
@@ -179,3 +195,65 @@ func (i *LndHtlcInterceptor) mapFailureCode(original interceptor.InterceptFailur
 		return lnrpc.Failure_TEMPORARY_CHANNEL_FAILURE
 	}
 }
+
+func (i *LndHtlcInterceptor) constructOnion(
+	interceptResult interceptor.InterceptResult,
+	reqOutgoingExpiry uint32,
+	reqPaymentHash []byte,
+) ([]byte, error) {
+	pubKey, err := btcec.ParsePubKey(interceptResult.Destination)
+	if err != nil {
+		log.Printf("btcec.ParsePubKey(%x): %v", interceptResult.Destination, err)
+		return nil, err
+	}
+
+	sessionKey, err := btcec.NewPrivateKey()
+	if err != nil {
+		log.Printf("btcec.NewPrivateKey(): %v", err)
+		return nil, err
+	}
+
+	var addr [32]byte
+	copy(addr[:], interceptResult.PaymentSecret)
+	hop := route.Hop{
+		AmtToForward:     lnwire.MilliSatoshi(interceptResult.AmountMsat),
+		OutgoingTimeLock: reqOutgoingExpiry,
+		MPP:              record.NewMPP(lnwire.MilliSatoshi(interceptResult.TotalAmountMsat), addr),
+		CustomRecords:    make(record.CustomSet),
+	}
+
+	var b bytes.Buffer
+	err = hop.PackHopPayload(&b, uint64(0))
+	if err != nil {
+		log.Printf("hop.PackHopPayload(): %v", err)
+		return nil, err
+	}
+
+	payload, err := sphinx.NewHopPayload(nil, b.Bytes())
+	if err != nil {
+		log.Printf("sphinx.NewHopPayload(): %v", err)
+		return nil, err
+	}
+
+	var sphinxPath sphinx.PaymentPath
+	sphinxPath[0] = sphinx.OnionHop{
+		NodePub:    *pubKey,
+		HopPayload: payload,
+	}
+	sphinxPacket, err := sphinx.NewOnionPacket(
+		&sphinxPath, sessionKey, reqPaymentHash,
+		sphinx.DeterministicPacketFiller,
+	)
+	if err != nil {
+		log.Printf("sphinx.NewOnionPacket(): %v", err)
+		return nil, err
+	}
+	var onionBlob bytes.Buffer
+	err = sphinxPacket.Encode(&onionBlob)
+	if err != nil {
+		log.Printf("sphinxPacket.Encode(): %v", err)
+		return nil, err
+	}
+
+	return onionBlob.Bytes(), nil
+}