[Server] Validate forfeit txs without re-building them (ark-network#382)

* compute forfeit partial tx client-side first

* fix conflict

* go work sync

* move verify sig in VerifyForfeits

* move check after len(inputs)

common/fees.go

@@ -28,28 +28,16 @@ var ConnectorTxSize = (&input.TxWeightEstimator{}).
 
 func ComputeForfeitMinRelayFee(
 	feeRate chainfee.SatPerKVByte,
-	vtxoScriptTapTree TaprootTree,
+	tapscript *waddrmgr.Tapscript,
+	witnessSize int,
 	aspScriptClass txscript.ScriptClass,
 ) (uint64, error) {
 	txWeightEstimator := &input.TxWeightEstimator{}
 
-	biggestVtxoLeafProof, err := BiggestLeafMerkleProof(vtxoScriptTapTree)
-	if err != nil {
-		return 0, err
-	}
-
-	ctrlBlock, err := txscript.ParseControlBlock(biggestVtxoLeafProof.ControlBlock)
-	if err != nil {
-		return 0, err
-	}
-
 	txWeightEstimator.AddP2PKHInput() // connector input
 	txWeightEstimator.AddTapscriptInput(
-		64*2, // forfeit witness = 2 signatures
-		&waddrmgr.Tapscript{
-			RevealedScript: biggestVtxoLeafProof.Script,
-			ControlBlock:   ctrlBlock,
-		},
+		lntypes.WeightUnit(witnessSize),
+		tapscript,
 	)
 
 	switch aspScriptClass {

pkg/client-sdk/covenant_client.go

@@ -21,6 +21,7 @@ import (
 	"github.com/btcsuite/btcd/btcec/v2/schnorr"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/txscript"
+	"github.com/btcsuite/btcwallet/waddrmgr"
 	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 	log "github.com/sirupsen/logrus"
@@ -1461,11 +1462,6 @@ func (a *covenantArkClient) createAndSignForfeits(
 			return nil, err
 		}
 
-		feeAmount, err := common.ComputeForfeitMinRelayFee(feeRate, vtxoTapTree, txscript.WitnessV0PubKeyHashTy)
-		if err != nil {
-			return nil, err
-		}
-
 		vtxoOutputScript, err := common.P2TRScript(vtxoTapKey)
 		if err != nil {
 			return nil, err
@@ -1477,13 +1473,15 @@ func (a *covenantArkClient) createAndSignForfeits(
 		}
 
 		var forfeitClosure tree.Closure
+		var witnessSize int
 
 		switch s := vtxoScript.(type) {
 		case *tree.DefaultVtxoScript:
 			forfeitClosure = &tree.MultisigClosure{
 				Pubkey:    s.Owner,
 				AspPubkey: a.AspPubkey,
 			}
+			witnessSize = 64 * 2
 		default:
 			return nil, fmt.Errorf("unsupported vtxo script: %T", s)
 		}
@@ -1508,6 +1506,19 @@ func (a *covenantArkClient) createAndSignForfeits(
 			ControlBlock:    *ctrlBlock,
 		}
 
+		feeAmount, err := common.ComputeForfeitMinRelayFee(
+			feeRate,
+			&waddrmgr.Tapscript{
+				RevealedScript: leafProof.Script,
+				ControlBlock:   &ctrlBlock.ControlBlock,
+			},
+			witnessSize,
+			txscript.WitnessV0PubKeyHashTy,
+		)
+		if err != nil {
+			return nil, err
+		}
+
 		for _, connectorPset := range connectorsPsets {
 			forfeits, err := tree.BuildForfeitTxs(
 				connectorPset, vtxoInput, vtxo.Amount, a.Dust, feeAmount, vtxoOutputScript, forfeitPkScript,

pkg/client-sdk/covenantless_client.go

@@ -28,6 +28,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
+	"github.com/btcsuite/btcwallet/waddrmgr"
 	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 	log "github.com/sirupsen/logrus"
@@ -2111,11 +2112,6 @@ func (a *covenantlessArkClient) createAndSignForfeits(
 			return nil, err
 		}
 
-		feeAmount, err := common.ComputeForfeitMinRelayFee(feeRate, vtxoTapTree, parsedScript.Class())
-		if err != nil {
-			return nil, err
-		}
-
 		vtxoOutputScript, err := common.P2TRScript(vtxoTapKey)
 		if err != nil {
 			return nil, err
@@ -2132,13 +2128,15 @@ func (a *covenantlessArkClient) createAndSignForfeits(
 		}
 
 		var forfeitClosure bitcointree.Closure
+		var witnessSize int
 
 		switch v := vtxoScript.(type) {
 		case *bitcointree.DefaultVtxoScript:
 			forfeitClosure = &bitcointree.MultisigClosure{
 				Pubkey:    v.Owner,
 				AspPubkey: a.AspPubkey,
 			}
+			witnessSize = 64 * 2
 		default:
 			return nil, fmt.Errorf("unsupported vtxo script: %T", vtxoScript)
 		}
@@ -2159,6 +2157,24 @@ func (a *covenantlessArkClient) createAndSignForfeits(
 			LeafVersion:  txscript.BaseLeafVersion,
 		}
 
+		ctrlBlock, err := txscript.ParseControlBlock(leafProof.ControlBlock)
+		if err != nil {
+			return nil, err
+		}
+
+		feeAmount, err := common.ComputeForfeitMinRelayFee(
+			feeRate,
+			&waddrmgr.Tapscript{
+				RevealedScript: leafProof.Script,
+				ControlBlock:   ctrlBlock,
+			},
+			witnessSize,
+			parsedScript.Class(),
+		)
+		if err != nil {
+			return nil, err
+		}
+
 		for _, connectorPset := range connectorsPsets {
 			forfeits, err := bitcointree.BuildForfeitTxs(
 				connectorPset, vtxoInput, vtxo.Amount, a.Dust, feeAmount, vtxoOutputScript, forfeitPkScript,

pkg/client-sdk/go.mod

@@ -10,6 +10,7 @@ require (
 	github.com/btcsuite/btcd/btcutil v1.1.5
 	github.com/btcsuite/btcd/btcutil/psbt v1.1.9
 	github.com/btcsuite/btcd/chaincfg/chainhash v1.1.0
+	github.com/btcsuite/btcwallet v0.16.10-0.20240718224643-db3a4a2543bd
 	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.3.0
 	github.com/dgraph-io/badger/v4 v4.3.0
 	github.com/go-openapi/errors v0.22.0
@@ -30,6 +31,7 @@ require (
 	github.com/aead/siphash v1.0.1 // indirect
 	github.com/asaskevich/govalidator v0.0.0-20230301143203-a9d515a09cc2 // indirect
 	github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f // indirect
+	github.com/btcsuite/btcwallet/walletdb v1.4.2 // indirect
 	github.com/btcsuite/go-socks v0.0.0-20170105172521-4720035b7bfd // indirect
 	github.com/btcsuite/websocket v0.0.0-20150119174127-31079b680792 // indirect
 	github.com/btcsuite/winsvc v1.0.0 // indirect
@@ -59,7 +61,9 @@ require (
 	github.com/jrick/logrotate v1.0.0 // indirect
 	github.com/kkdai/bstream v1.0.0 // indirect
 	github.com/klauspost/compress v1.17.9 // indirect
+	github.com/lightninglabs/neutrino/cache v1.1.2 // indirect
 	github.com/lightningnetwork/lnd/fn v1.2.1 // indirect
+	github.com/lightningnetwork/lnd/tlv v1.2.6 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
 	github.com/oklog/ulid v1.3.1 // indirect
@@ -71,6 +75,7 @@ require (
 	github.com/stretchr/objx v0.5.2 // indirect
 	github.com/syndtr/goleveldb v1.0.1-0.20210819022825-2ae1ddf74ef7 // indirect
 	github.com/vulpemventures/fastsha256 v0.0.0-20160815193821-637e65642941 // indirect
+	go.etcd.io/bbolt v1.3.10 // indirect
 	go.mongodb.org/mongo-driver v1.14.0 // indirect
 	go.opencensus.io v0.24.0 // indirect
 	go.opentelemetry.io/otel v1.30.0 // indirect

pkg/client-sdk/go.sum

@@ -24,6 +24,8 @@ github.com/btcsuite/btcd/chaincfg/chainhash v1.1.0/go.mod h1:7SFka0XMvUgj3hfZtyd
 github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f h1:bAs4lUbRJpnnkd9VhRV3jjAVU7DJVjMaK+IsvSeZvFo=
 github.com/btcsuite/btclog v0.0.0-20170628155309-84c8d2346e9f/go.mod h1:TdznJufoqS23FtqVCzL0ZqgP5MqXbb4fg/WgDys70nA=
 github.com/btcsuite/btcutil v0.0.0-20190425235716-9e5f4b9a998d/go.mod h1:+5NJ2+qvTyV9exUAL/rxXi3DcLg2Ts+ymUAY5y4NvMg=
+github.com/btcsuite/btcwallet v0.16.10-0.20240718224643-db3a4a2543bd h1:QDb8foTCRoXrfoZVEzSYgSde16MJh4gCtCin8OCS0kI=
+github.com/btcsuite/btcwallet/walletdb v1.4.2 h1:zwZZ+zaHo4mK+FAN6KeK85S3oOm+92x2avsHvFAhVBE=
 github.com/btcsuite/go-socks v0.0.0-20170105172521-4720035b7bfd h1:R/opQEbFEy9JGkIguV40SvRY1uliPX8ifOvi6ICsFCw=
 github.com/btcsuite/go-socks v0.0.0-20170105172521-4720035b7bfd/go.mod h1:HHNXQzUsZCxOoE+CPiyCTO6x34Zs86zZUiwtpXoGdtg=
 github.com/btcsuite/goleveldb v0.0.0-20160330041536-7834afc9e8cd/go.mod h1:F+uVaaLLH7j4eDXPRvw78tMflu7Ie2bzYOH4Y8rRKBY=
@@ -175,10 +177,12 @@ github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/lightninglabs/neutrino/cache v1.1.2 h1:C9DY/DAPaPxbFC+xNNEI/z1SJY9GS3shmlu5hIQ798g=
 github.com/lightningnetwork/lnd v0.18.2-beta h1:Qv4xQ2ka05vqzmdkFdISHCHP6CzHoYNVKfD18XPjHsM=
 github.com/lightningnetwork/lnd v0.18.2-beta/go.mod h1:cGQR1cVEZFZQcCx2VBbDY8xwGjCz+SupSopU1HpjP2I=
 github.com/lightningnetwork/lnd/fn v1.2.1 h1:pPsVGrwi9QBwdLJzaEGK33wmiVKOxs/zc8H7+MamFf0=
 github.com/lightningnetwork/lnd/fn v1.2.1/go.mod h1:SyFohpVrARPKH3XVAJZlXdVe+IwMYc4OMAvrDY32kw0=
+github.com/lightningnetwork/lnd/tlv v1.2.6 h1:icvQG2yDr6k3ZuZzfRdG3EJp6pHurcuh3R6dg0gv/Mw=
 github.com/magiconair/properties v1.8.0/go.mod h1:PppfXfuXeibc/6YijjN8zIbojt8czPbwD3XqdrwzmxQ=
 github.com/mailru/easyjson v0.7.7 h1:UGYAvKxe3sBsEDzO8ZeWOSlIQfWFlxbzLZe7hwFURr0=
 github.com/mailru/easyjson v0.7.7/go.mod h1:xzfreul335JAWq5oZzymOObrkdz5UnU4kGfJJLY9Nlc=
@@ -252,6 +256,7 @@ github.com/xordataexchange/crypt v0.0.3-0.20170626215501-b2862e3d0a77/go.mod h1:
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+go.etcd.io/bbolt v1.3.10 h1:+BqfJTcCzTItrop8mq/lbzL8wSGtj94UO/3U31shqG0=
 go.mongodb.org/mongo-driver v1.14.0 h1:P98w8egYRjYe3XDjxhYJagTokP/H6HzlsnojRgZRd80=
 go.mongodb.org/mongo-driver v1.14.0/go.mod h1:Vzb0Mk/pa7e6cWw85R4F/endUC3u0U9jGcNU603k65c=
 go.opencensus.io v0.22.5/go.mod h1:5pWMHQbX5EPX2/62yrJeAkowc+lfs/XD7Uxpq3pI6kk=

server/internal/core/application/covenant.go

@@ -181,7 +181,6 @@ func (s *covenantService) SpendNotes(_ context.Context, _ []note.Note) (string,
 func (s *covenantService) SpendVtxos(ctx context.Context, inputs []ports.Input) (string, error) {
 	vtxosInputs := make([]domain.Vtxo, 0)
 	boardingInputs := make([]ports.BoardingInput, 0)
-	descriptors := make(map[domain.VtxoKey]string)
 
 	now := time.Now().Unix()
 
@@ -243,15 +242,33 @@ func (s *covenantService) SpendVtxos(ctx context.Context, inputs []ports.Input)
 			return "", fmt.Errorf("input %s:%d already swept", vtxo.Txid, vtxo.VOut)
 		}
 
+		vtxoScript, err := tree.ParseVtxoScript(input.Descriptor)
+		if err != nil {
+			return "", fmt.Errorf("failed to parse boarding descriptor: %s", err)
+		}
+
+		tapKey, _, err := vtxoScript.TapTree()
+		if err != nil {
+			return "", fmt.Errorf("failed to get taproot key: %s", err)
+		}
+
+		expectedTapKey, err := vtxo.TapKey()
+		if err != nil {
+			return "", fmt.Errorf("failed to get taproot key: %s", err)
+		}
+
+		if !bytes.Equal(schnorr.SerializePubKey(tapKey), schnorr.SerializePubKey(expectedTapKey)) {
+			return "", fmt.Errorf("descriptor does not match vtxo pubkey")
+		}
+
 		vtxosInputs = append(vtxosInputs, vtxo)
-		descriptors[vtxo.VtxoKey] = input.Descriptor
 	}
 
 	payment, err := domain.NewPayment(vtxosInputs)
 	if err != nil {
 		return "", err
 	}
-	if err := s.paymentRequests.push(*payment, boardingInputs, descriptors); err != nil {
+	if err := s.paymentRequests.push(*payment, boardingInputs); err != nil {
 		return "", err
 	}
 	return payment.Id, nil
@@ -519,7 +536,7 @@ func (s *covenantService) startFinalization() {
 	if num > paymentsThreshold {
 		num = paymentsThreshold
 	}
-	payments, boardingInputs, descriptors, _, _ := s.paymentRequests.pop(num)
+	payments, boardingInputs, _, _ := s.paymentRequests.pop(num)
 	if _, err := round.RegisterPayments(payments); err != nil {
 		round.Fail(fmt.Errorf("failed to register payments: %s", err))
 		log.WithError(err).Warn("failed to register payments")
@@ -533,42 +550,15 @@ func (s *covenantService) startFinalization() {
 		return
 	}
 
-	unsignedPoolTx, tree, connectorAddress, err := s.builder.BuildRoundTx(s.pubkey, payments, boardingInputs, sweptRounds)
+	unsignedPoolTx, tree, connectorAddress, connectors, err := s.builder.BuildRoundTx(s.pubkey, payments, boardingInputs, sweptRounds)
 	if err != nil {
 		round.Fail(fmt.Errorf("failed to create pool tx: %s", err))
 		log.WithError(err).Warn("failed to create pool tx")
 		return
 	}
 	log.Debugf("pool tx created for round %s", round.Id)
 
-	needForfeits := false
-	for _, pay := range payments {
-		if len(pay.Inputs) > 0 {
-			needForfeits = true
-			break
-		}
-	}
-
-	var forfeitTxs, connectors []string
-
-	minRelayFeeRate := s.wallet.MinRelayFeeRate(ctx)
-
-	if needForfeits {
-		connectors, forfeitTxs, err = s.builder.BuildForfeitTxs(unsignedPoolTx, payments, descriptors, minRelayFeeRate)
-		if err != nil {
-			round.Fail(fmt.Errorf("failed to create connectors and forfeit txs: %s", err))
-			log.WithError(err).Warn("failed to create connectors and forfeit txs")
-			return
-		}
-
-		log.Debugf("forfeit transactions created for round %s", round.Id)
-
-		if err := s.forfeitTxs.push(forfeitTxs); err != nil {
-			round.Fail(fmt.Errorf("failed to cache forfeit txs: %s", err))
-			log.WithError(err).Warn("failed to cache forfeit txs")
-			return
-		}
-	}
+	s.forfeitTxs.init(connectors, payments)
 
 	if _, err := round.StartFinalization(
 		connectorAddress, connectors, tree, unsignedPoolTx,
@@ -598,9 +588,8 @@ func (s *covenantService) finalizeRound() {
 		}
 	}()
 
-	forfeitTxs, leftUnsigned := s.forfeitTxs.pop()
-	if len(leftUnsigned) > 0 {
-		err := fmt.Errorf("%d forfeit txs left to sign", len(leftUnsigned))
+	forfeitTxs, err := s.forfeitTxs.pop()
+	if err != nil {
 		changes = round.Fail(fmt.Errorf("failed to finalize round: %s", err))
 		log.WithError(err).Warn("failed to finalize round")
 		return