From 2010239b631ae3196a20036e03602b464381a96e Mon Sep 17 00:00:00 2001
From: Olaoluwa Osuntokun <laolu32@gmail.com>
Date: Wed, 1 Mar 2023 22:14:12 -0800
Subject: [PATCH] contractcourt: update the anchor resolver for taproot chans

---
 contractcourt/anchor_resolver.go    | 20 ++++++++++++++------
 contractcourt/chain_watcher.go      |  3 ++-
 contractcourt/channel_arbitrator.go | 23 +++++++++++++++++++++--
 3 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/contractcourt/anchor_resolver.go b/contractcourt/anchor_resolver.go
index 80ac45631..d96960026 100644
--- a/contractcourt/anchor_resolver.go
+++ b/contractcourt/anchor_resolver.go
@@ -33,6 +33,9 @@ type anchorResolver struct {
 	// chanPoint is the channel point of the original contract.
 	chanPoint wire.OutPoint
 
+	// chanType denotes the type of channel the contract belongs to.
+	chanType channeldb.ChannelType
+
 	// currentReport stores the current state of the resolver for reporting
 	// over the rpc interface.
 	currentReport ContractReport
@@ -97,12 +100,16 @@ func (c *anchorResolver) Resolve() (ContractResolver, error) {
 	// to the sweeper.
 	relayFeeRate := c.Sweeper.RelayFeePerKW()
 
+	witnessType := input.CommitmentAnchor
+
+	// For taproot channels, we need to use the proper witness type.
+	if c.chanType.IsTaproot() {
+		witnessType = input.TaprootAnchorSweepSpend
+	}
+
 	anchorInput := input.MakeBaseInput(
-		&c.anchor,
-		input.CommitmentAnchor,
-		&c.anchorSignDescriptor,
-		c.broadcastHeight,
-		nil,
+		&c.anchor, witnessType, &c.anchorSignDescriptor,
+		c.broadcastHeight, nil,
 	)
 
 	resultChan, err := c.Sweeper.SweepInput(
@@ -195,7 +202,8 @@ func (c *anchorResolver) IsResolved() bool {
 // state required for the proper resolution of a contract.
 //
 // NOTE: Part of the ContractResolver interface.
-func (c *anchorResolver) SupplementState(_ *channeldb.OpenChannel) {
+func (c *anchorResolver) SupplementState(state *channeldb.OpenChannel) {
+	c.chanType = state.ChanType
 }
 
 // report returns a report on the resolution state of the contract.
diff --git a/contractcourt/chain_watcher.go b/contractcourt/chain_watcher.go
index 9d788fed4..3b0ee9664 100644
--- a/contractcourt/chain_watcher.go
+++ b/contractcourt/chain_watcher.go
@@ -885,7 +885,8 @@ func (c *chainWatcher) handlePossibleBreach(commitSpend *chainntnfs.SpendDetail,
 	// TODO(roasbeef): make keyring for taproot chans to pass in instead of
 	// nil
 	anchorRes, err := lnwallet.NewAnchorResolution(
-		c.cfg.chanState, commitSpend.SpendingTx, nil, false,
+		c.cfg.chanState, commitSpend.SpendingTx, retribution.KeyRing,
+		false,
 	)
 	if err != nil {
 		return false, fmt.Errorf("unable to create anchor "+
diff --git a/contractcourt/channel_arbitrator.go b/contractcourt/channel_arbitrator.go
index 3eb3ffb87..33b3385d2 100644
--- a/contractcourt/channel_arbitrator.go
+++ b/contractcourt/channel_arbitrator.go
@@ -11,6 +11,7 @@ import (
 
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/channeldb"
@@ -728,7 +729,7 @@ func (c *ChannelArbitrator) relaunchResolvers(commitSet *CommitSet,
 	for i := range unresolvedContracts {
 		resolver := unresolvedContracts[i]
 
-        if chanState != nil {
+		if chanState != nil {
 			resolver.SupplementState(chanState)
 		}
 
@@ -766,7 +767,12 @@ func (c *ChannelArbitrator) relaunchResolvers(commitSet *CommitSet,
 				ChannelArbitratorConfig: c.cfg,
 			},
 		)
+
+		anchorResolver.SupplementState(chanState)
+
 		unresolvedContracts = append(unresolvedContracts, anchorResolver)
+
+		// TODO(roasbeef): this isn't re-launched?
 	}
 
 	c.launchResolvers(unresolvedContracts)
@@ -1292,10 +1298,21 @@ func (c *ChannelArbitrator) sweepAnchors(anchors *lnwallet.AnchorResolutions,
 			"anchor of %s commit tx %v", c.cfg.ChanPoint,
 			anchorPath, anchor.CommitAnchor)
 
+		witnessType := input.CommitmentAnchor
+
+		// For taproot channels, we need to use the proper witness
+		// type.
+		if txscript.IsPayToTaproot(
+			anchor.AnchorSignDescriptor.Output.PkScript,
+		) {
+
+			witnessType = input.TaprootAnchorSweepSpend
+		}
+
 		// Prepare anchor output for sweeping.
 		anchorInput := input.MakeBaseInput(
 			&anchor.CommitAnchor,
-			input.CommitmentAnchor,
+			witnessType,
 			&anchor.AnchorSignDescriptor,
 			heightHint,
 			&input.TxInfo{
@@ -2181,6 +2198,8 @@ func (c *ChannelArbitrator) prepContractResolutions(
 			contractResolutions.AnchorResolution.CommitAnchor,
 			height, c.cfg.ChanPoint, resolverCfg,
 		)
+		anchorResolver.SupplementState(chanState)
+
 		htlcResolvers = append(htlcResolvers, anchorResolver)
 	}