From 064d010e76ec662f002fe62433dbd4e50835e51f Mon Sep 17 00:00:00 2001
From: Joost Jager <joost.jager@gmail.com>
Date: Mon, 24 Oct 2022 11:33:00 +0200
Subject: [PATCH] wip

---
 go.mod         |  4 +++-
 go.sum         |  6 ++----
 interceptor.go |  9 +++++----
 mux.go         | 24 ++++++++++++++++++++----
 4 files changed, 30 insertions(+), 13 deletions(-)

diff --git a/go.mod b/go.mod
index 3bddc7f..3ffa4a7 100644
--- a/go.mod
+++ b/go.mod
@@ -103,7 +103,7 @@ require (
 	github.com/lightningnetwork/lnd/kvdb v1.3.1 // indirect
 	github.com/lightningnetwork/lnd/ticker v1.1.0 // indirect
 	github.com/lightningnetwork/lnd/tlv v1.0.3 // indirect
-	github.com/lightningnetwork/lnd/tor v1.0.1 // indirect
+	github.com/lightningnetwork/lnd/tor v1.1.0 // indirect
 	github.com/ltcsuite/ltcd v0.20.1-beta // indirect
 	github.com/mailru/easyjson v0.7.6 // indirect
 	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
@@ -182,3 +182,5 @@ require (
 )
 
 replace github.com/bottlepay/lnmux/lnmuxrpc => ./lnmuxrpc
+
+replace github.com/lightningnetwork/lnd => /users/Joost.Jager/lightninglabs/lnd
diff --git a/go.sum b/go.sum
index 168d310..8569031 100644
--- a/go.sum
+++ b/go.sum
@@ -507,8 +507,6 @@ github.com/lightninglabs/neutrino v0.14.2 h1:yrnZUCYMZ5ECtXhgDrzqPq2oX8awoAN2D/c
 github.com/lightninglabs/neutrino v0.14.2/go.mod h1:OICUeTCn+4Tu27YRJIpWvvqySxx4oH4vgdP33Sw9RDc=
 github.com/lightningnetwork/lightning-onion v1.0.2-0.20220211021909-bb84a1ccb0c5 h1:TkKwqFcQTGYoI+VEqyxA8rxpCin8qDaYX0AfVRinT3k=
 github.com/lightningnetwork/lightning-onion v1.0.2-0.20220211021909-bb84a1ccb0c5/go.mod h1:7dDx73ApjEZA0kcknI799m2O5kkpfg4/gr7N092ojNo=
-github.com/lightningnetwork/lnd v0.15.3-beta h1:mm7fyXMgZPRyh0fFLO3tnvfvXszp/kVnGGciS76Wefs=
-github.com/lightningnetwork/lnd v0.15.3-beta/go.mod h1:UaCwJBMCJbwPMsUjfTIaKPKF8K79btRPnhqfiNPyKtA=
 github.com/lightningnetwork/lnd/clock v1.0.1/go.mod h1:KnQudQ6w0IAMZi1SgvecLZQZ43ra2vpDNj7H/aasemg=
 github.com/lightningnetwork/lnd/clock v1.1.0 h1:/yfVAwtPmdx45aQBoXQImeY7sOIEr7IXlImRMBOZ7GQ=
 github.com/lightningnetwork/lnd/clock v1.1.0/go.mod h1:KnQudQ6w0IAMZi1SgvecLZQZ43ra2vpDNj7H/aasemg=
@@ -527,8 +525,8 @@ github.com/lightningnetwork/lnd/tlv v1.0.2/go.mod h1:fICAfsqk1IOsC1J7G9IdsWX1EqW
 github.com/lightningnetwork/lnd/tlv v1.0.3 h1:0xBZcPuXagP6f7TY/RnLNR4igE21ov6qUdTr5NyvhhI=
 github.com/lightningnetwork/lnd/tlv v1.0.3/go.mod h1:dzR/aZetBri+ZY/fHbwV06fNn/3UID6htQzbHfREFdo=
 github.com/lightningnetwork/lnd/tor v1.0.0/go.mod h1:RDtaAdwfAm+ONuPYwUhNIH1RAvKPv+75lHPOegUcz64=
-github.com/lightningnetwork/lnd/tor v1.0.1 h1:A11FrpU0Y//g+fA827W4VnjOeoIvExONdchlLX8wYkA=
-github.com/lightningnetwork/lnd/tor v1.0.1/go.mod h1:RDtaAdwfAm+ONuPYwUhNIH1RAvKPv+75lHPOegUcz64=
+github.com/lightningnetwork/lnd/tor v1.1.0 h1:iXO7fSzjxTI+p88KmtpbuyuRJeNfgtpl9QeaAliILXE=
+github.com/lightningnetwork/lnd/tor v1.1.0/go.mod h1:RDtaAdwfAm+ONuPYwUhNIH1RAvKPv+75lHPOegUcz64=
 github.com/ltcsuite/ltcd v0.20.1-beta h1:ka9ZwUG7oUPppl+7ptuh5VDxGD7TWEJXu/IOOOz1yfY=
 github.com/ltcsuite/ltcd v0.20.1-beta/go.mod h1:ZFQaYdYULIuTQiWqs7AUiHD2XhDFeeHW1IH+UYMdABU=
 github.com/ltcsuite/ltcutil v0.0.0-20191227053721-6bec450ea6ad/go.mod h1:8Vg/LTOO0KYa/vlHWJ6XZAevPQThGH5sufO0Hrou/lA=
diff --git a/interceptor.go b/interceptor.go
index b74ea84..be4d722 100644
--- a/interceptor.go
+++ b/interceptor.go
@@ -156,10 +156,11 @@ func (i *interceptor) start(ctx context.Context) error {
 					ChanId: item.incomingKey.ChanID,
 					HtlcId: item.incomingKey.HtlcID,
 				},
-				Action:         item.resp.action,
-				Preimage:       item.resp.preimage[:],
-				FailureMessage: item.resp.failureMessage,
-				FailureCode:    item.resp.failureCode,
+				Action:                    item.resp.action,
+				Preimage:                  item.resp.preimage[:],
+				FailureMessage:            item.resp.failureMessage,
+				FailureCode:               item.resp.failureCode,
+				FailureMessageUnencrypted: item.resp.failureMessageUnencrypted,
 			}
 
 			if err := send(rpcResp); err != nil {
diff --git a/mux.go b/mux.go
index b915e19..0dd6d11 100644
--- a/mux.go
+++ b/mux.go
@@ -115,10 +115,11 @@ type interceptedHtlc struct {
 }
 
 type interceptedHtlcResponse struct {
-	action         routerrpc.ResolveHoldForwardAction
-	preimage       lntypes.Preimage
-	failureMessage []byte
-	failureCode    lnrpc.Failure_FailureCode
+	action                    routerrpc.ResolveHoldForwardAction
+	preimage                  lntypes.Preimage
+	failureMessage            []byte
+	failureCode               lnrpc.Failure_FailureCode
+	failureMessageUnencrypted bool
 }
 
 func (p *Mux) run(mainCtx context.Context) error {
@@ -236,6 +237,21 @@ func (p *Mux) ProcessHtlc(
 	fail := func(code lnwire.FailCode) error {
 		logger.Debugw("Failing htlc", "code", code)
 
+		if code == lnwire.CodeFeeInsufficient {
+			wireMsg := lnwire.NewFeeInsufficient(0, lnwire.ChannelUpdate{})
+			var w bytes.Buffer
+			err := lnwire.EncodeFailureMessage(&w, wireMsg, 0)
+			if err != nil {
+				return err
+			}
+
+			return htlc.reply(&interceptedHtlcResponse{
+				action:                    routerrpc.ResolveHoldForwardAction_FAIL,
+				failureMessage:            w.Bytes(),
+				failureMessageUnencrypted: true,
+			})
+		}
+
 		rpcCode, err := marshallFailureCode(code)
 		if err != nil {
 			return err