From 1760fe30db09db99db6b6134afd4a96b2b230f71 Mon Sep 17 00:00:00 2001
From: Conner Fromknecht <conner@lightning.engineering>
Date: Wed, 12 Aug 2020 15:45:48 -0700
Subject: [PATCH] fundingmanager: cache remote-max-htlcs in res context

Currenlty the maxHtlcs value is recomputed after receiving
accept_channel. This works when the derivation is deterministic, howver
we now allow the user to manually override this value from open_channel.
As such, we must retain the chosen value in memory throughout the
funding process, otherwise the initiator would revert to the
deterministic derivation and the two endpoints will disagree on the
correct max-htlcs value in their view of the other's policy.
---
 fundingmanager.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fundingmanager.go b/fundingmanager.go
index e6a53dc0b..c2343b8f2 100644
--- a/fundingmanager.go
+++ b/fundingmanager.go
@@ -124,6 +124,7 @@ type reservationWithCtx struct {
 	remoteCsvDelay uint16
 	remoteMinHtlc  lnwire.MilliSatoshi
 	remoteMaxValue lnwire.MilliSatoshi
+	remoteMaxHtlcs uint16
 
 	updateMtx   sync.RWMutex
 	lastUpdated time.Time
@@ -1411,6 +1412,7 @@ func (f *fundingManager) handleFundingOpen(fmsg *fundingOpenMsg) {
 		remoteCsvDelay: remoteCsvDelay,
 		remoteMinHtlc:  minHtlc,
 		remoteMaxValue: remoteMaxValue,
+		remoteMaxHtlcs: maxHtlcs,
 		err:            make(chan error, 1),
 		peer:           fmsg.peer,
 	}
@@ -1560,7 +1562,6 @@ func (f *fundingManager) handleFundingAccept(fmsg *fundingAcceptMsg) {
 	// here so we can properly commit their accepted constraints to the
 	// reservation.
 	chanReserve := f.cfg.RequiredRemoteChanReserve(resCtx.chanAmt, msg.DustLimit)
-	maxHtlcs := f.cfg.RequiredRemoteMaxHTLCs(resCtx.chanAmt)
 
 	// The remote node has responded with their portion of the channel
 	// contribution. At this point, we can process their contribution which
@@ -1574,7 +1575,7 @@ func (f *fundingManager) handleFundingAccept(fmsg *fundingAcceptMsg) {
 				MaxPendingAmount: resCtx.remoteMaxValue,
 				ChanReserve:      chanReserve,
 				MinHTLC:          resCtx.remoteMinHtlc,
-				MaxAcceptedHtlcs: maxHtlcs,
+				MaxAcceptedHtlcs: resCtx.remoteMaxHtlcs,
 				CsvDelay:         resCtx.remoteCsvDelay,
 			},
 			MultiSigKey: keychain.KeyDescriptor{
@@ -3267,6 +3268,7 @@ func (f *fundingManager) handleInitFundingMsg(msg *initFundingMsg) {
 		remoteCsvDelay: remoteCsvDelay,
 		remoteMinHtlc:  minHtlcIn,
 		remoteMaxValue: maxValue,
+		remoteMaxHtlcs: maxHtlcs,
 		reservation:    reservation,
 		peer:           msg.peer,
 		updates:        msg.updates,