From 8432e706d35535f091a9f31e9c69fe4746b41d42 Mon Sep 17 00:00:00 2001
From: Olaoluwa Osuntokun <laolu32@gmail.com>
Date: Mon, 10 Feb 2025 19:05:52 -0800
Subject: [PATCH] multi: extract new DeriveHeightHint() function, use for new
 rbf closer

With this commit, we make sure we set the right height hint, even if the
channel is a zero conf channel.
---
 channeldb/channel.go           | 28 ++++++++++++++++++++++++++++
 contractcourt/chain_watcher.go | 30 +-----------------------------
 lnwallet/channel.go            |  8 ++++++++
 3 files changed, 37 insertions(+), 29 deletions(-)

diff --git a/channeldb/channel.go b/channeldb/channel.go
index 6bf20373c..e16537f1c 100644
--- a/channeldb/channel.go
+++ b/channeldb/channel.go
@@ -4104,6 +4104,34 @@ func (c *OpenChannel) AbsoluteThawHeight() (uint32, error) {
 	return c.ThawHeight, nil
 }
 
+// DeriveHeightHint derives the block height for the channel opening.
+func (c *OpenChannel) DeriveHeightHint() uint32 {
+	// As a height hint, we'll try to use the opening height, but if the
+	// channel isn't yet open, then we'll use the height it was broadcast
+	// at. This may be an unconfirmed zero-conf channel.
+	heightHint := c.ShortChanID().BlockHeight
+	if heightHint == 0 {
+		heightHint = c.BroadcastHeight()
+	}
+
+	// Since no zero-conf state is stored in a channel backup, the below
+	// logic will not be triggered for restored, zero-conf channels. Set
+	// the height hint for zero-conf channels.
+	if c.IsZeroConf() {
+		if c.ZeroConfConfirmed() {
+			// If the zero-conf channel is confirmed, we'll use the
+			// confirmed SCID's block height.
+			heightHint = c.ZeroConfRealScid().BlockHeight
+		} else {
+			// The zero-conf channel is unconfirmed. We'll need to
+			// use the FundingBroadcastHeight.
+			heightHint = c.BroadcastHeight()
+		}
+	}
+
+	return heightHint
+}
+
 func putChannelCloseSummary(tx kvdb.RwTx, chanID []byte,
 	summary *ChannelCloseSummary, lastChanState *OpenChannel) error {
 
diff --git a/contractcourt/chain_watcher.go b/contractcourt/chain_watcher.go
index fef70b945..06665af29 100644
--- a/contractcourt/chain_watcher.go
+++ b/contractcourt/chain_watcher.go
@@ -281,7 +281,7 @@ func newChainWatcher(cfg chainWatcherConfig) (*chainWatcher, error) {
 	}
 
 	// Get the channel opening block height.
-	heightHint := deriveHeightHint(chanState)
+	heightHint := chanState.DeriveHeightHint()
 
 	// We'll register for a notification to be dispatched if the funding
 	// output is spent.
@@ -1328,34 +1328,6 @@ func deriveFundingPkScript(chanState *channeldb.OpenChannel) ([]byte, error) {
 	return fundingPkScript, nil
 }
 
-// deriveHeightHint derives the block height for the channel opening.
-func deriveHeightHint(chanState *channeldb.OpenChannel) uint32 {
-	// As a height hint, we'll try to use the opening height, but if the
-	// channel isn't yet open, then we'll use the height it was broadcast
-	// at. This may be an unconfirmed zero-conf channel.
-	heightHint := chanState.ShortChanID().BlockHeight
-	if heightHint == 0 {
-		heightHint = chanState.BroadcastHeight()
-	}
-
-	// Since no zero-conf state is stored in a channel backup, the below
-	// logic will not be triggered for restored, zero-conf channels. Set
-	// the height hint for zero-conf channels.
-	if chanState.IsZeroConf() {
-		if chanState.ZeroConfConfirmed() {
-			// If the zero-conf channel is confirmed, we'll use the
-			// confirmed SCID's block height.
-			heightHint = chanState.ZeroConfRealScid().BlockHeight
-		} else {
-			// The zero-conf channel is unconfirmed. We'll need to
-			// use the FundingBroadcastHeight.
-			heightHint = chanState.BroadcastHeight()
-		}
-	}
-
-	return heightHint
-}
-
 // handleCommitSpend takes a spending tx of the funding output and handles the
 // channel close based on the closure type.
 func (c *chainWatcher) handleCommitSpend(
diff --git a/lnwallet/channel.go b/lnwallet/channel.go
index bc9820e8f..aa8e21e76 100644
--- a/lnwallet/channel.go
+++ b/lnwallet/channel.go
@@ -9874,6 +9874,14 @@ func (lc *LightningChannel) FundingTxOut() *wire.TxOut {
 	return &lc.fundingOutput
 }
 
+// DeriveHeightHint derives the block height for the channel opening.
+func (lc *LightningChannel) DeriveHeightHint() uint32 {
+	lc.RLock()
+	defer lc.RUnlock()
+
+	return lc.channelState.DeriveHeightHint()
+}
+
 // MultiSigKeys returns the set of multi-sig keys for an channel.
 func (lc *LightningChannel) MultiSigKeys() (keychain.KeyDescriptor,
 	keychain.KeyDescriptor) {