lnd/lnwallet/witnessgen.go

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package lnwallet
import (
"fmt"
"github.com/roasbeef/btcd/txscript"
"github.com/roasbeef/btcd/wire"
)
// WitnessType determines how an output's witness will be generated. The
// default commitmentTimeLock type will generate a witness that will allow
// spending of a time-locked transaction enforced by CheckSequenceVerify.
type WitnessType uint16
const (
// CommitmentTimeLock is a witness that allows us to spend the output of
// a commitment transaction after a relative lock-time lockout.
CommitmentTimeLock WitnessType = 0
// CommitmentNoDelay is a witness that allows us to spend a settled
// no-delay output immediately on a counterparty's commitment
// transaction.
CommitmentNoDelay WitnessType = 1
// CommitmentRevoke is a witness that allows us to sweep the settled
// output of a malicious counterparty's who broadcasts a revoked
// commitment transaction.
CommitmentRevoke WitnessType = 2
// HtlcOfferedRevoke is a witness that allows us to sweep an HTLC
// output that we offered to the counterparty.
HtlcOfferedRevoke WitnessType = 3
// HtlcAcceptedRevoke is a witness that allows us to sweep an HTLC
// output that we accepted from the counterparty.
HtlcAcceptedRevoke WitnessType = 4
// HtlcOfferedTimeout is a witness that allows us to sweep an HTLC
// output that we extended to a party, but was never fulfilled.
HtlcOfferedTimeout WitnessType = 5
// HtlcAcceptedSuccess is a witness that allows us to sweep an HTLC
// output that was offered to us, and for which we have a payment
// preimage.
HtlcAcceptedSuccess WitnessType = 6
)
// WitnessGenerator represents a function which is able to generate the final
// witness for a particular public key script. This function acts as an
// abstraction layer, hiding the details of the underlying script.
type WitnessGenerator func(tx *wire.MsgTx, hc *txscript.TxSigHashes,
inputIndex int) ([][]byte, error)
// GenWitnessFunc will return a WitnessGenerator function that an output
// uses to generate the witness for a sweep transaction.
func (wt WitnessType) GenWitnessFunc(signer Signer,
descriptor *SignDescriptor) WitnessGenerator {
return func(tx *wire.MsgTx, hc *txscript.TxSigHashes,
inputIndex int) ([][]byte, error) {
desc := descriptor
desc.SigHashes = hc
desc.InputIndex = inputIndex
switch wt {
case CommitmentTimeLock:
return CommitSpendTimeout(signer, desc, tx)
case CommitmentNoDelay:
return CommitSpendNoDelay(signer, desc, tx)
case CommitmentRevoke:
return CommitSpendRevoke(signer, desc, tx)
case HtlcOfferedRevoke:
return ReceiverHtlcSpendRevoke(signer, desc, tx)
case HtlcAcceptedRevoke:
return SenderHtlcSpendRevoke(signer, desc, tx)
case HtlcOfferedTimeout:
return HtlcSpendSuccess(signer, desc, tx)
default:
return nil, fmt.Errorf("unknown witness type: %v", wt)
}
}
}