multi: use prev output fetcher where possible

input/input.go

@@ -42,6 +42,7 @@ type Input interface {
 	// also nested p2sh outputs.
 	CraftInputScript(signer Signer, txn *wire.MsgTx,
 		hashCache *txscript.TxSigHashes,
+		prevOutputFetcher txscript.PrevOutputFetcher,
 		txinIdx int) (*Script, error)
 
 	// BlocksToMaturity returns the relative timelock, as a number of
@@ -221,9 +222,13 @@ func NewCsvInputWithCltv(outpoint *wire.OutPoint, witnessType WitnessType,
 // txIndex within the passed transaction. The input scripts generated by this
 // method support spending p2wkh, p2wsh, and also nested p2sh outputs.
 func (bi *BaseInput) CraftInputScript(signer Signer, txn *wire.MsgTx,
-	hashCache *txscript.TxSigHashes, txinIdx int) (*Script, error) {
+	hashCache *txscript.TxSigHashes,
+	prevOutputFetcher txscript.PrevOutputFetcher, txinIdx int) (*Script,
+	error) {
 
-	witnessFunc := bi.witnessType.WitnessGenerator(signer, bi.SignDesc())
+	signDesc := bi.SignDesc()
+	signDesc.PrevOutputFetcher = prevOutputFetcher
+	witnessFunc := bi.witnessType.WitnessGenerator(signer, signDesc)
 
 	return witnessFunc(txn, hashCache, txinIdx)
 }
@@ -260,11 +265,14 @@ func MakeHtlcSucceedInput(outpoint *wire.OutPoint,
 // txIndex within the passed transaction. The input scripts generated by this
 // method support spending p2wkh, p2wsh, and also nested p2sh outputs.
 func (h *HtlcSucceedInput) CraftInputScript(signer Signer, txn *wire.MsgTx,
-	hashCache *txscript.TxSigHashes, txinIdx int) (*Script, error) {
+	hashCache *txscript.TxSigHashes,
+	prevOutputFetcher txscript.PrevOutputFetcher, txinIdx int) (*Script,
+	error) {
 
 	desc := h.signDesc
 	desc.SigHashes = hashCache
 	desc.InputIndex = txinIdx
+	desc.PrevOutputFetcher = prevOutputFetcher
 
 	witness, err := SenderHtlcSpendRedeem(
 		signer, &desc, txn, h.preimage,
@@ -291,7 +299,9 @@ type HtlcSecondLevelAnchorInput struct {
 	// createWitness creates a witness allowing the passed transaction to
 	// spend the input.
 	createWitness func(signer Signer, txn *wire.MsgTx,
-		hashCache *txscript.TxSigHashes, txinIdx int) (wire.TxWitness, error)
+		hashCache *txscript.TxSigHashes,
+		prevOutputFetcher txscript.PrevOutputFetcher,
+		txinIdx int) (wire.TxWitness, error)
 }
 
 // RequiredTxOut returns the tx out needed to be present on the sweep tx for
@@ -313,9 +323,12 @@ func (i *HtlcSecondLevelAnchorInput) RequiredLockTime() (uint32, bool) {
 // method support spending p2wkh, p2wsh, and also nested p2sh outputs.
 func (i *HtlcSecondLevelAnchorInput) CraftInputScript(signer Signer,
 	txn *wire.MsgTx, hashCache *txscript.TxSigHashes,
-	txinIdx int) (*Script, error) {
+	prevOutputFetcher txscript.PrevOutputFetcher, txinIdx int) (*Script,
+	error) {
 
-	witness, err := i.createWitness(signer, txn, hashCache, txinIdx)
+	witness, err := i.createWitness(
+		signer, txn, hashCache, prevOutputFetcher, txinIdx,
+	)
 	if err != nil {
 		return nil, err
 	}
@@ -335,11 +348,13 @@ func MakeHtlcSecondLevelTimeoutAnchorInput(signedTx *wire.MsgTx,
 	// 2nd timeout transaction.
 	createWitness := func(signer Signer, txn *wire.MsgTx,
 		hashCache *txscript.TxSigHashes,
+		prevOutputFetcher txscript.PrevOutputFetcher,
 		txinIdx int) (wire.TxWitness, error) {
 
 		desc := signDetails.SignDesc
-		desc.SigHashes = NewTxSigHashesV0Only(txn)
+		desc.SigHashes = txscript.NewTxSigHashes(txn, prevOutputFetcher)
 		desc.InputIndex = txinIdx
+		desc.PrevOutputFetcher = prevOutputFetcher
 
 		return SenderHtlcSpendTimeout(
 			signDetails.PeerSig, signDetails.SigHashType, signer,
@@ -373,11 +388,13 @@ func MakeHtlcSecondLevelSuccessAnchorInput(signedTx *wire.MsgTx,
 	// success transaction.
 	createWitness := func(signer Signer, txn *wire.MsgTx,
 		hashCache *txscript.TxSigHashes,
+		prevOutputFetcher txscript.PrevOutputFetcher,
 		txinIdx int) (wire.TxWitness, error) {
 
 		desc := signDetails.SignDesc
 		desc.SigHashes = hashCache
 		desc.InputIndex = txinIdx
+		desc.PrevOutputFetcher = prevOutputFetcher
 
 		return ReceiverHtlcSpendRedeem(
 			signDetails.PeerSig, signDetails.SigHashType,

input/signdescriptor.go

@@ -74,6 +74,11 @@ type SignDescriptor struct {
 	// generating the final sighash for signing.
 	SigHashes *txscript.TxSigHashes
 
+	// PrevOutputFetcher is an interface that can return the output
+	// information on all UTXOs that are being spent in this transaction.
+	// This MUST be set when spending Taproot outputs.
+	PrevOutputFetcher txscript.PrevOutputFetcher
+
 	// InputIndex is the target input within the transaction that should be
 	// signed.
 	InputIndex int

input/taproot.go

@@ -1,6 +1,8 @@
 package input
 
 import (
+	"fmt"
+
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 )
@@ -18,3 +20,25 @@ func NewTxSigHashesV0Only(tx *wire.MsgTx) *txscript.TxSigHashes {
 	nilFetcher := txscript.NewCannedPrevOutputFetcher(nil, 0)
 	return txscript.NewTxSigHashes(tx, nilFetcher)
 }
+
+// MultiPrevOutFetcher returns a txscript.MultiPrevOutFetcher for the given set
+// of inputs.
+func MultiPrevOutFetcher(inputs []Input) (*txscript.MultiPrevOutFetcher, error) {
+	fetcher := txscript.NewMultiPrevOutFetcher(nil)
+	for _, inp := range inputs {
+		op := inp.OutPoint()
+		desc := inp.SignDesc()
+
+		if op == nil {
+			return nil, fmt.Errorf("missing input outpoint")
+		}
+
+		if desc == nil || desc.Output == nil {
+			return nil, fmt.Errorf("missing input utxo information")
+		}
+
+		fetcher.AddPrevOut(*op, desc.Output)
+	}
+
+	return fetcher, nil
+}