Release v0.3.0

vendor/github.com/lightningnetwork/lnd/input/input.go

@@ -0,0 +1,200 @@
+package input
+
+import (
+	"github.com/btcsuite/btcd/txscript"
+	"github.com/btcsuite/btcd/wire"
+)
+
+// Input represents an abstract UTXO which is to be spent using a sweeping
+// transaction. The method provided give the caller all information needed to
+// construct a valid input within a sweeping transaction to sweep this
+// lingering UTXO.
+type Input interface {
+	// Outpoint returns the reference to the output being spent, used to
+	// construct the corresponding transaction input.
+	OutPoint() *wire.OutPoint
+
+	// WitnessType returns an enum specifying the type of witness that must
+	// be generated in order to spend this output.
+	WitnessType() WitnessType
+
+	// SignDesc returns a reference to a spendable output's sign
+	// descriptor, which is used during signing to compute a valid witness
+	// that spends this output.
+	SignDesc() *SignDescriptor
+
+	// CraftInputScript returns a valid set of input scripts allowing this
+	// output to be spent. The returns input scripts should target the
+	// input at location txIndex within the passed transaction. The input
+	// scripts generated by this method support spending p2wkh, p2wsh, and
+	// also nested p2sh outputs.
+	CraftInputScript(signer Signer, txn *wire.MsgTx,
+		hashCache *txscript.TxSigHashes,
+		txinIdx int) (*Script, error)
+
+	// BlocksToMaturity returns the relative timelock, as a number of
+	// blocks, that must be built on top of the confirmation height before
+	// the output can be spent. For non-CSV locked inputs this is always
+	// zero.
+	BlocksToMaturity() uint32
+
+	// HeightHint returns the minimum height at which a confirmed spending
+	// tx can occur.
+	HeightHint() uint32
+}
+
+type inputKit struct {
+	outpoint        wire.OutPoint
+	witnessType     WitnessType
+	signDesc        SignDescriptor
+	heightHint      uint32
+	blockToMaturity uint32
+}
+
+// OutPoint returns the breached output's identifier that is to be included as
+// a transaction input.
+func (i *inputKit) OutPoint() *wire.OutPoint {
+	return &i.outpoint
+}
+
+// WitnessType returns the type of witness that must be generated to spend the
+// breached output.
+func (i *inputKit) WitnessType() WitnessType {
+	return i.witnessType
+}
+
+// SignDesc returns the breached output's SignDescriptor, which is used during
+// signing to compute the witness.
+func (i *inputKit) SignDesc() *SignDescriptor {
+	return &i.signDesc
+}
+
+// HeightHint returns the minimum height at which a confirmed spending
+// tx can occur.
+func (i *inputKit) HeightHint() uint32 {
+	return i.heightHint
+}
+
+// BlocksToMaturity returns the relative timelock, as a number of blocks, that
+// must be built on top of the confirmation height before the output can be
+// spent. For non-CSV locked inputs this is always zero.
+func (i *inputKit) BlocksToMaturity() uint32 {
+	return i.blockToMaturity
+}
+
+// BaseInput contains all the information needed to sweep a basic output
+// (CSV/CLTV/no time lock)
+type BaseInput struct {
+	inputKit
+}
+
+// MakeBaseInput assembles a new BaseInput that can be used to construct a
+// sweep transaction.
+func MakeBaseInput(outpoint *wire.OutPoint, witnessType WitnessType,
+	signDescriptor *SignDescriptor, heightHint uint32) BaseInput {
+
+	return BaseInput{
+		inputKit{
+			outpoint:    *outpoint,
+			witnessType: witnessType,
+			signDesc:    *signDescriptor,
+			heightHint:  heightHint,
+		},
+	}
+}
+
+// NewBaseInput allocates and assembles a new *BaseInput that can be used to
+// construct a sweep transaction.
+func NewBaseInput(outpoint *wire.OutPoint, witnessType WitnessType,
+	signDescriptor *SignDescriptor, heightHint uint32) *BaseInput {
+
+	input := MakeBaseInput(
+		outpoint, witnessType, signDescriptor, heightHint,
+	)
+
+	return &input
+}
+
+// NewCsvInput assembles a new csv-locked input that can be used to
+// construct a sweep transaction.
+func NewCsvInput(outpoint *wire.OutPoint, witnessType WitnessType,
+	signDescriptor *SignDescriptor, heightHint uint32,
+	blockToMaturity uint32) *BaseInput {
+
+	return &BaseInput{
+		inputKit{
+			outpoint:        *outpoint,
+			witnessType:     witnessType,
+			signDesc:        *signDescriptor,
+			heightHint:      heightHint,
+			blockToMaturity: blockToMaturity,
+		},
+	}
+}
+
+// CraftInputScript returns a valid set of input scripts allowing this output
+// to be spent. The returned input scripts should target the input at location
+// 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) {
+
+	witnessFunc := bi.witnessType.WitnessGenerator(signer, bi.SignDesc())
+
+	return witnessFunc(txn, hashCache, txinIdx)
+}
+
+// HtlcSucceedInput constitutes a sweep input that needs a pre-image. The input
+// is expected to reside on the commitment tx of the remote party and should
+// not be a second level tx output.
+type HtlcSucceedInput struct {
+	inputKit
+
+	preimage []byte
+}
+
+// MakeHtlcSucceedInput assembles a new redeem input that can be used to
+// construct a sweep transaction.
+func MakeHtlcSucceedInput(outpoint *wire.OutPoint,
+	signDescriptor *SignDescriptor, preimage []byte, heightHint,
+	blocksToMaturity uint32) HtlcSucceedInput {
+
+	return HtlcSucceedInput{
+		inputKit: inputKit{
+			outpoint:        *outpoint,
+			witnessType:     HtlcAcceptedRemoteSuccess,
+			signDesc:        *signDescriptor,
+			heightHint:      heightHint,
+			blockToMaturity: blocksToMaturity,
+		},
+		preimage: preimage,
+	}
+}
+
+// CraftInputScript returns a valid set of input scripts allowing this output
+// to be spent. The returns input scripts should target the input at location
+// 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) {
+
+	desc := h.signDesc
+	desc.SigHashes = hashCache
+	desc.InputIndex = txinIdx
+
+	witness, err := SenderHtlcSpendRedeem(
+		signer, &desc, txn, h.preimage,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Script{
+		Witness: witness,
+	}, nil
+}
+
+// Compile-time constraints to ensure each input struct implement the Input
+// interface.
+var _ Input = (*BaseInput)(nil)
+var _ Input = (*HtlcSucceedInput)(nil)