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input+sweep: rework witness type into an interface

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This commit is contained in:
Oliver Gugger
2019-10-07 13:41:46 +02:00
parent 8e4a897a60
commit fb0051a318
5 changed files with 196 additions and 144 deletions
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4
input/input.go
View File

@@ -114,9 +114,7 @@ func NewBaseInput(outpoint *wire.OutPoint, witnessType WitnessType,
func (bi *BaseInput) CraftInputScript(signer Signer, txn *wire.MsgTx,
hashCache *txscript.TxSigHashes, txinIdx int) (*Script, error) {
witnessFunc := bi.witnessType.GenWitnessFunc(
signer, bi.SignDesc(),
)
witnessFunc := bi.witnessType.WitnessGenerator(signer, bi.SignDesc())
return witnessFunc(txn, hashCache, txinIdx)
}

203
input/witnessgen.go
View File

@@ -7,87 +7,125 @@ import (
"github.com/btcsuite/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
// WitnessGenerator represents a function that is able to generate the final
// witness for a particular public key script. Additionally, if required, this
// function will also return the sigScript for spending nested P2SH witness
// outputs. 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) (*Script, error)
// WitnessType determines how an output's witness will be generated. This
// interface can be implemented to be used for custom sweep scripts if the
// pre-defined StandardWitnessType list doesn't provide a suitable one.
type WitnessType interface {
// String returns a human readable version of the WitnessType.
String() string
// WitnessGenerator will return a WitnessGenerator function that an
// output uses to generate the witness and optionally the sigScript for
// a sweep transaction.
WitnessGenerator(signer Signer,
descriptor *SignDescriptor) WitnessGenerator
// SizeUpperBound returns the maximum length of the witness of this
// WitnessType if it would be included in a tx. It also returns if the
// output itself is a nested p2sh output, if so then we need to take
// into account the extra sigScript data size.
SizeUpperBound() (int, bool, error)
// AddWeightEstimation adds the estimated size of the witness in bytes
// to the given weight estimator and returns the number of
// CSVs/CLTVs used by the script.
AddWeightEstimation(estimator *TxWeightEstimator) (int, int, error)
}
// StandardWitnessType is a numeric representation of standard pre-defined types
// of witness configurations.
type StandardWitnessType uint16
// A compile time check to ensure StandardWitnessType implements the
// WitnessType interface.
var _ WitnessType = (StandardWitnessType)(0)
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
CommitmentTimeLock StandardWitnessType = 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
CommitmentNoDelay StandardWitnessType = 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
CommitmentRevoke StandardWitnessType = 2
// HtlcOfferedRevoke is a witness that allows us to sweep an HTLC which
// we offered to the remote party in the case that they broadcast a
// revoked commitment state.
HtlcOfferedRevoke WitnessType = 3
HtlcOfferedRevoke StandardWitnessType = 3
// HtlcAcceptedRevoke is a witness that allows us to sweep an HTLC
// output sent to us in the case that the remote party broadcasts a
// revoked commitment state.
HtlcAcceptedRevoke WitnessType = 4
HtlcAcceptedRevoke StandardWitnessType = 4
// HtlcOfferedTimeoutSecondLevel is a witness that allows us to sweep
// an HTLC output that we extended to a party, but was never fulfilled.
// This HTLC output isn't directly on the commitment transaction, but
// is the result of a confirmed second-level HTLC transaction. As a
// result, we can only spend this after a CSV delay.
HtlcOfferedTimeoutSecondLevel WitnessType = 5
HtlcOfferedTimeoutSecondLevel StandardWitnessType = 5
// HtlcAcceptedSuccessSecondLevel is a witness that allows us to sweep
// an HTLC output that was offered to us, and for which we have a
// payment preimage. This HTLC output isn't directly on our commitment
// transaction, but is the result of confirmed second-level HTLC
// transaction. As a result, we can only spend this after a CSV delay.
HtlcAcceptedSuccessSecondLevel WitnessType = 6
HtlcAcceptedSuccessSecondLevel StandardWitnessType = 6
// HtlcOfferedRemoteTimeout is a witness that allows us to sweep an
// HTLC that we offered to the remote party which lies in the
// commitment transaction of the remote party. We can spend this output
// after the absolute CLTV timeout of the HTLC as passed.
HtlcOfferedRemoteTimeout WitnessType = 7
HtlcOfferedRemoteTimeout StandardWitnessType = 7
// HtlcAcceptedRemoteSuccess is a witness that allows us to sweep an
// HTLC that was offered to us by the remote party. We use this witness
// in the case that the remote party goes to chain, and we know the
// pre-image to the HTLC. We can sweep this without any additional
// timeout.
HtlcAcceptedRemoteSuccess WitnessType = 8
HtlcAcceptedRemoteSuccess StandardWitnessType = 8
// HtlcSecondLevelRevoke is a witness that allows us to sweep an HTLC
// from the remote party's commitment transaction in the case that the
// broadcast a revoked commitment, but then also immediately attempt to
// go to the second level to claim the HTLC.
HtlcSecondLevelRevoke WitnessType = 9
HtlcSecondLevelRevoke StandardWitnessType = 9
// WitnessKeyHash is a witness type that allows us to spend a regular
// p2wkh output that's sent to an output which is under complete
// control of the backing wallet.
WitnessKeyHash WitnessType = 10
WitnessKeyHash StandardWitnessType = 10
// NestedWitnessKeyHash is a witness type that allows us to sweep an
// output that sends to a nested P2SH script that pays to a key solely
// under our control. The witness generated needs to include the
NestedWitnessKeyHash WitnessType = 11
NestedWitnessKeyHash StandardWitnessType = 11
// CommitSpendNoDelayTweakless is similar to the CommitSpendNoDelay
// type, but it omits the tweak that randomizes the key we need to
// spend with a channel peer supplied set of randomness.
CommitSpendNoDelayTweakless = 12
CommitSpendNoDelayTweakless StandardWitnessType = 12
)
// Stirng returns a human readable version of the target WitnessType.
func (wt WitnessType) String() string {
// String returns a human readable version of the target WitnessType.
//
// NOTE: This is part of the WitnessType interface.
func (wt StandardWitnessType) String() string {
switch wt {
case CommitmentTimeLock:
return "CommitmentTimeLock"
@@ -127,19 +165,13 @@ func (wt WitnessType) String() string {
}
}
// WitnessGenerator represents a function which is able to generate the final
// witness for a particular public key script. Additionally, if required, this
// function will also return the sigScript for spending nested P2SH witness
// outputs. 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) (*Script, error)
// GenWitnessFunc will return a WitnessGenerator function that an output uses
// WitnessGenerator will return a WitnessGenerator function that an output uses
// to generate the witness and optionally the sigScript for a sweep
// transaction. The sigScript will be generated if the witness type warrants
// one for spending, such as the NestedWitnessKeyHash witness type.
func (wt WitnessType) GenWitnessFunc(signer Signer,
//
// NOTE: This is part of the WitnessType interface.
func (wt StandardWitnessType) WitnessGenerator(signer Signer,
descriptor *SignDescriptor) WitnessGenerator {
return func(tx *wire.MsgTx, hc *txscript.TxSigHashes,
@@ -262,5 +294,116 @@ func (wt WitnessType) GenWitnessFunc(signer Signer,
return nil, fmt.Errorf("unknown witness type: %v", wt)
}
}
}
// SizeUpperBound returns the maximum length of the witness of this witness
// type if it would be included in a tx. We also return if the output itself is
// a nested p2sh output, if so then we need to take into account the extra
// sigScript data size.
//
// NOTE: This is part of the WitnessType interface.
func (wt StandardWitnessType) SizeUpperBound() (int, bool, error) {
switch wt {
// Outputs on a remote commitment transaction that pay directly to us.
case CommitSpendNoDelayTweakless:
fallthrough
case WitnessKeyHash:
fallthrough
case CommitmentNoDelay:
return P2WKHWitnessSize, false, nil
// Outputs on a past commitment transaction that pay directly
// to us.
case CommitmentTimeLock:
return ToLocalTimeoutWitnessSize, false, nil
// Outgoing second layer HTLC's that have confirmed within the
// chain, and the output they produced is now mature enough to
// sweep.
case HtlcOfferedTimeoutSecondLevel:
return ToLocalTimeoutWitnessSize, false, nil
// Incoming second layer HTLC's that have confirmed within the
// chain, and the output they produced is now mature enough to
// sweep.
case HtlcAcceptedSuccessSecondLevel:
return ToLocalTimeoutWitnessSize, false, nil
// An HTLC on the commitment transaction of the remote party,
// that has had its absolute timelock expire.
case HtlcOfferedRemoteTimeout:
return AcceptedHtlcTimeoutWitnessSize, false, nil
// An HTLC on the commitment transaction of the remote party,
// that can be swept with the preimage.
case HtlcAcceptedRemoteSuccess:
return OfferedHtlcSuccessWitnessSize, false, nil
// A nested P2SH input that has a p2wkh witness script. We'll mark this
// as nested P2SH so the caller can estimate the weight properly
// including the sigScript.
case NestedWitnessKeyHash:
return P2WKHWitnessSize, true, nil
// The revocation output on a revoked commitment transaction.
case CommitmentRevoke:
return ToLocalPenaltyWitnessSize, false, nil
// The revocation output on a revoked HTLC that we offered to the remote
// party.
case HtlcOfferedRevoke:
return OfferedHtlcPenaltyWitnessSize, false, nil
// The revocation output on a revoked HTLC that was sent to us.
case HtlcAcceptedRevoke:
return AcceptedHtlcPenaltyWitnessSize, false, nil
// The revocation output of a second level output of an HTLC.
case HtlcSecondLevelRevoke:
return ToLocalPenaltyWitnessSize, false, nil
}
return 0, false, fmt.Errorf("unexpected witness type: %v", wt)
}
// AddWeightEstimation adds the estimated size of the witness in bytes to the
// given weight estimator and returns the number of CSVs/CLTVs used by the
// script.
//
// NOTE: This is part of the WitnessType interface.
func (wt StandardWitnessType) AddWeightEstimation(
estimator *TxWeightEstimator) (int, int, error) {
var (
csvCount = 0
cltvCount = 0
)
// For fee estimation purposes, we'll now attempt to obtain an
// upper bound on the weight this input will add when fully
// populated.
size, isNestedP2SH, err := wt.SizeUpperBound()
if err != nil {
return 0, 0, err
}
// If this is a nested P2SH input, then we'll need to factor in
// the additional data push within the sigScript.
if isNestedP2SH {
estimator.AddNestedP2WSHInput(size)
} else {
estimator.AddWitnessInput(size)
}
switch wt {
case CommitmentTimeLock,
HtlcOfferedTimeoutSecondLevel,
HtlcAcceptedSuccessSecondLevel:
csvCount++
case HtlcOfferedRemoteTimeout:
cltvCount++
}
return csvCount, cltvCount, nil
}