lnd.xprv/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 (
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// CommitmentTimeLock is a witness that allows us to spend the output of a
// commitment transaction after a relative lock-time lockout.
CommitmentTimeLock WitnessType = 0
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// CommitmentNoDelay is a witness that allows us to spend a settled no-delay
// output immediately on a counterparty's commitment transaction.
CommitmentNoDelay WitnessType = 1
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// 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
)
// 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)
default:
return nil, fmt.Errorf("unknown witness type: %v", wt)
}
}
}