From 88eae6eafe8ad54945a9501537244cf4cb6b3de1 Mon Sep 17 00:00:00 2001
From: Joost Jager <joost.jager@gmail.com>
Date: Mon, 10 Feb 2020 13:52:19 +0100
Subject: [PATCH] lnwallet: fix invalid value use in restoreUpdate

Updates were always restored with the same log index. This could cause a
crash when the logs were compacted and possibly other problems
elsewhere.

Extended unit test to cover the crash scenario.
---
 lnwallet/channel.go      |  2 +-
 lnwallet/channel_test.go | 16 +++++++++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/lnwallet/channel.go b/lnwallet/channel.go
index bc472598..131d8632 100644
--- a/lnwallet/channel.go
+++ b/lnwallet/channel.go
@@ -1064,7 +1064,7 @@ func (u *updateLog) appendUpdate(pd *PaymentDescriptor) {
 // also added to index accordingly. This function differs from appendUpdate in
 // that it won't increment the log index counter.
 func (u *updateLog) restoreUpdate(pd *PaymentDescriptor) {
-	u.updateIndex[u.logIndex] = u.PushBack(pd)
+	u.updateIndex[pd.LogIndex] = u.PushBack(pd)
 }
 
 // appendHtlc appends a new HTLC offer to the tip of the update log. The entry
diff --git a/lnwallet/channel_test.go b/lnwallet/channel_test.go
index 03ac925f..1e871ab6 100644
--- a/lnwallet/channel_test.go
+++ b/lnwallet/channel_test.go
@@ -3146,7 +3146,7 @@ func TestChanSyncOweCommitmentPendingRemote(t *testing.T) {
 	}
 
 	// Bob signs the commitment he owes.
-	_, bobHtlcSigs, _, err := bobChannel.SignNextCommitment()
+	bobCommit, bobHtlcSigs, _, err := bobChannel.SignNextCommitment()
 	if err != nil {
 		t.Fatalf("unable to sign commitment: %v", err)
 	}
@@ -3155,6 +3155,20 @@ func TestChanSyncOweCommitmentPendingRemote(t *testing.T) {
 	if len(bobHtlcSigs) != 0 {
 		t.Fatalf("no htlcs expected, but got %v", len(bobHtlcSigs))
 	}
+
+	// Get Alice to revoke and trigger Bob to compact his logs.
+	err = aliceChannel.ReceiveNewCommitment(bobCommit, bobHtlcSigs)
+	if err != nil {
+		t.Fatal(err)
+	}
+	aliceRevoke, _, err := aliceChannel.RevokeCurrentCommitment()
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, _, _, _, err = bobChannel.ReceiveRevocation(aliceRevoke)
+	if err != nil {
+		t.Fatal(err)
+	}
 }
 
 // TestChanSyncOweRevocation tests that if Bob restarts (and then Alice) before