lnd.xprv/input/size.go
Johan T. Halseth 02dd8d23fd
input/size: remove unused constants
Since we never attempt to sweep an HTLC we offered with the preimage on
the remote's commitment, we never use the constant
AcceptedHtlcSuccessWitnessSize for weight estimation. Similarly, we
never timout an HTLC offered by the remote on our own commitment, and
don't need the constant OfferedHtlcTimeoutWitnessSize.
2020-03-09 12:10:57 +01:00

467 lines
16 KiB
Go

package input
import (
"github.com/btcsuite/btcd/blockchain"
"github.com/btcsuite/btcd/wire"
)
const (
// witnessScaleFactor determines the level of "discount" witness data
// receives compared to "base" data. A scale factor of 4, denotes that
// witness data is 1/4 as cheap as regular non-witness data. Value copied
// here for convenience.
witnessScaleFactor = blockchain.WitnessScaleFactor
// The weight(weight), which is different from the !size! (see BIP-141),
// is calculated as:
// Weight = 4 * BaseSize + WitnessSize (weight).
// BaseSize - size of the transaction without witness data (bytes).
// WitnessSize - witness size (bytes).
// Weight - the metric for determining the weight of the transaction.
// P2WPKHSize 22 bytes
// - OP_0: 1 byte
// - OP_DATA: 1 byte (PublicKeyHASH160 length)
// - PublicKeyHASH160: 20 bytes
P2WPKHSize = 1 + 1 + 20
// P2WSHSize 34 bytes
// - OP_0: 1 byte
// - OP_DATA: 1 byte (WitnessScriptSHA256 length)
// - WitnessScriptSHA256: 32 bytes
P2WSHSize = 1 + 1 + 32
// P2PKHOutputSize 34 bytes
// - value: 8 bytes
// - var_int: 1 byte (pkscript_length)
// - pkscript (p2pkh): 25 bytes
P2PKHOutputSize = 8 + 1 + 25
// P2WKHOutputSize 31 bytes
// - value: 8 bytes
// - var_int: 1 byte (pkscript_length)
// - pkscript (p2wpkh): 22 bytes
P2WKHOutputSize = 8 + 1 + P2WPKHSize
// P2WSHOutputSize 43 bytes
// - value: 8 bytes
// - var_int: 1 byte (pkscript_length)
// - pkscript (p2wsh): 34 bytes
P2WSHOutputSize = 8 + 1 + P2WSHSize
// P2SHOutputSize 32 bytes
// - value: 8 bytes
// - var_int: 1 byte (pkscript_length)
// - pkscript (p2sh): 23 bytes
P2SHOutputSize = 8 + 1 + 23
// P2PKHScriptSigSize 108 bytes
// - OP_DATA: 1 byte (signature length)
// - signature
// - OP_DATA: 1 byte (pubkey length)
// - pubkey
P2PKHScriptSigSize = 1 + 73 + 1 + 33
// P2WKHWitnessSize 109 bytes
// - number_of_witness_elements: 1 byte
// - signature_length: 1 byte
// - signature
// - pubkey_length: 1 byte
// - pubkey
P2WKHWitnessSize = 1 + 1 + 73 + 1 + 33
// MultiSigSize 71 bytes
// - OP_2: 1 byte
// - OP_DATA: 1 byte (pubKeyAlice length)
// - pubKeyAlice: 33 bytes
// - OP_DATA: 1 byte (pubKeyBob length)
// - pubKeyBob: 33 bytes
// - OP_2: 1 byte
// - OP_CHECKMULTISIG: 1 byte
MultiSigSize = 1 + 1 + 33 + 1 + 33 + 1 + 1
// WitnessSize 222 bytes
// - NumberOfWitnessElements: 1 byte
// - NilLength: 1 byte
// - sigAliceLength: 1 byte
// - sigAlice: 73 bytes
// - sigBobLength: 1 byte
// - sigBob: 73 bytes
// - WitnessScriptLength: 1 byte
// - WitnessScript (MultiSig)
WitnessSize = 1 + 1 + 1 + 73 + 1 + 73 + 1 + MultiSigSize
// InputSize 41 bytes
// - PreviousOutPoint:
// - Hash: 32 bytes
// - Index: 4 bytes
// - OP_DATA: 1 byte (ScriptSigLength)
// - ScriptSig: 0 bytes
// - Witness <---- we use "Witness" instead of "ScriptSig" for
// transaction validation, but "Witness" is stored
// separately and weight for it size is smaller. So
// we separate the calculation of ordinary data
// from witness data.
// - Sequence: 4 bytes
InputSize = 32 + 4 + 1 + 4
// FundingInputSize represents the size of an input to a funding
// transaction, and is equivalent to the size of a standard segwit input
// as calculated above.
FundingInputSize = InputSize
// CommitmentDelayOutput 43 bytes
// - Value: 8 bytes
// - VarInt: 1 byte (PkScript length)
// - PkScript (P2WSH)
CommitmentDelayOutput = 8 + 1 + P2WSHSize
// CommitmentKeyHashOutput 31 bytes
// - Value: 8 bytes
// - VarInt: 1 byte (PkScript length)
// - PkScript (P2WPKH)
CommitmentKeyHashOutput = 8 + 1 + P2WPKHSize
// HTLCSize 43 bytes
// - Value: 8 bytes
// - VarInt: 1 byte (PkScript length)
// - PkScript (PW2SH)
HTLCSize = 8 + 1 + P2WSHSize
// WitnessHeaderSize 2 bytes
// - Flag: 1 byte
// - Marker: 1 byte
WitnessHeaderSize = 1 + 1
// BaseTxSize 8 bytes
// - Version: 4 bytes
// - LockTime: 4 bytes
BaseTxSize = 4 + 4
// BaseCommitmentTxSize 125 + 43 * num-htlc-outputs bytes
// - Version: 4 bytes
// - WitnessHeader <---- part of the witness data
// - CountTxIn: 1 byte
// - TxIn: 41 bytes
// FundingInput
// - CountTxOut: 1 byte
// - TxOut: 74 + 43 * num-htlc-outputs bytes
// OutputPayingToThem,
// OutputPayingToUs,
// ....HTLCOutputs...
// - LockTime: 4 bytes
BaseCommitmentTxSize = 4 + 1 + FundingInputSize + 1 +
CommitmentDelayOutput + CommitmentKeyHashOutput + 4
// BaseCommitmentTxWeight 500 weight
BaseCommitmentTxWeight = witnessScaleFactor * BaseCommitmentTxSize
// WitnessCommitmentTxWeight 224 weight
WitnessCommitmentTxWeight = WitnessHeaderSize + WitnessSize
// CommitWeight 724 weight
CommitWeight = BaseCommitmentTxWeight + WitnessCommitmentTxWeight
// HTLCWeight 172 weight
HTLCWeight = witnessScaleFactor * HTLCSize
// HtlcTimeoutWeight is the weight of the HTLC timeout transaction
// which will transition an outgoing HTLC to the delay-and-claim state.
HtlcTimeoutWeight = 663
// HtlcSuccessWeight is the weight of the HTLC success transaction
// which will transition an incoming HTLC to the delay-and-claim state.
HtlcSuccessWeight = 703
// MaxHTLCNumber is the maximum number HTLCs which can be included in a
// commitment transaction. This limit was chosen such that, in the case
// of a contract breach, the punishment transaction is able to sweep
// all the HTLC's yet still remain below the widely used standard
// weight limits.
MaxHTLCNumber = 966
// ToLocalScriptSize 79 bytes
// - OP_IF: 1 byte
// - OP_DATA: 1 byte
// - revoke_key: 33 bytes
// - OP_ELSE: 1 byte
// - OP_DATA: 1 byte
// - csv_delay: 4 bytes
// - OP_CHECKSEQUENCEVERIFY: 1 byte
// - OP_DROP: 1 byte
// - OP_DATA: 1 byte
// - delay_key: 33 bytes
// - OP_ENDIF: 1 byte
// - OP_CHECKSIG: 1 byte
ToLocalScriptSize = 1 + 1 + 33 + 1 + 1 + 4 + 1 + 1 + 1 + 33 + 1 + 1
// ToLocalTimeoutWitnessSize 156 bytes
// - number_of_witness_elements: 1 byte
// - local_delay_sig_length: 1 byte
// - local_delay_sig: 73 bytes
// - zero_length: 1 byte
// - witness_script_length: 1 byte
// - witness_script (to_local_script)
ToLocalTimeoutWitnessSize = 1 + 1 + 73 + 1 + 1 + ToLocalScriptSize
// ToLocalPenaltyWitnessSize 156 bytes
// - number_of_witness_elements: 1 byte
// - revocation_sig_length: 1 byte
// - revocation_sig: 73 bytes
// - OP_TRUE: 1 byte
// - witness_script_length: 1 byte
// - witness_script (to_local_script)
ToLocalPenaltyWitnessSize = 1 + 1 + 73 + 1 + 1 + ToLocalScriptSize
// AcceptedHtlcScriptSize 139 bytes
// - OP_DUP: 1 byte
// - OP_HASH160: 1 byte
// - OP_DATA: 1 byte (RIPEMD160(SHA256(revocationkey)) length)
// - RIPEMD160(SHA256(revocationkey)): 20 bytes
// - OP_EQUAL: 1 byte
// - OP_IF: 1 byte
// - OP_CHECKSIG: 1 byte
// - OP_ELSE: 1 byte
// - OP_DATA: 1 byte (remotekey length)
// - remotekey: 33 bytes
// - OP_SWAP: 1 byte
// - OP_SIZE: 1 byte
// - 32: 1 byte
// - OP_EQUAL: 1 byte
// - OP_IF: 1 byte
// - OP_HASH160: 1 byte
// - OP_DATA: 1 byte (RIPEMD160(payment_hash) length)
// - RIPEMD160(payment_hash): 20 bytes
// - OP_EQUALVERIFY: 1 byte
// - 2: 1 byte
// - OP_SWAP: 1 byte
// - OP_DATA: 1 byte (localkey length)
// - localkey: 33 bytes
// - 2: 1 byte
// - OP_CHECKMULTISIG: 1 byte
// - OP_ELSE: 1 byte
// - OP_DROP: 1 byte
// - OP_DATA: 1 byte (cltv_expiry length)
// - cltv_expiry: 4 bytes
// - OP_CHECKLOCKTIMEVERIFY: 1 byte
// - OP_DROP: 1 byte
// - OP_CHECKSIG: 1 byte
// - OP_ENDIF: 1 byte
// - OP_ENDIF: 1 byte
AcceptedHtlcScriptSize = 3*1 + 20 + 5*1 + 33 + 7*1 + 20 + 4*1 +
33 + 5*1 + 4 + 5*1
// AcceptedHtlcTimeoutWitnessSize 216
// - number_of_witness_elements: 1 byte
// - sender_sig_length: 1 byte
// - sender_sig: 73 bytes
// - nil_length: 1 byte
// - witness_script_length: 1 byte
// - witness_script: (accepted_htlc_script)
AcceptedHtlcTimeoutWitnessSize = 1 + 1 + 73 + 1 + 1 + AcceptedHtlcScriptSize
// AcceptedHtlcPenaltyWitnessSize 249 bytes
// - number_of_witness_elements: 1 byte
// - revocation_sig_length: 1 byte
// - revocation_sig: 73 bytes
// - revocation_key_length: 1 byte
// - revocation_key: 33 bytes
// - witness_script_length: 1 byte
// - witness_script (accepted_htlc_script)
AcceptedHtlcPenaltyWitnessSize = 1 + 1 + 73 + 1 + 33 + 1 + AcceptedHtlcScriptSize
// OfferedHtlcScriptSize 133 bytes
// - OP_DUP: 1 byte
// - OP_HASH160: 1 byte
// - OP_DATA: 1 byte (RIPEMD160(SHA256(revocationkey)) length)
// - RIPEMD160(SHA256(revocationkey)): 20 bytes
// - OP_EQUAL: 1 byte
// - OP_IF: 1 byte
// - OP_CHECKSIG: 1 byte
// - OP_ELSE: 1 byte
// - OP_DATA: 1 byte (remotekey length)
// - remotekey: 33 bytes
// - OP_SWAP: 1 byte
// - OP_SIZE: 1 byte
// - OP_DATA: 1 byte (32 length)
// - 32: 1 byte
// - OP_EQUAL: 1 byte
// - OP_NOTIF: 1 byte
// - OP_DROP: 1 byte
// - 2: 1 byte
// - OP_SWAP: 1 byte
// - OP_DATA: 1 byte (localkey length)
// - localkey: 33 bytes
// - 2: 1 byte
// - OP_CHECKMULTISIG: 1 byte
// - OP_ELSE: 1 byte
// - OP_HASH160: 1 byte
// - OP_DATA: 1 byte (RIPEMD160(payment_hash) length)
// - RIPEMD160(payment_hash): 20 bytes
// - OP_EQUALVERIFY: 1 byte
// - OP_CHECKSIG: 1 byte
// - OP_ENDIF: 1 byte
// - OP_ENDIF: 1 byte
OfferedHtlcScriptSize = 3*1 + 20 + 5*1 + 33 + 10*1 + 33 + 5*1 + 20 + 4*1
// OfferedHtlcSuccessWitnessSize 317 bytes
// - number_of_witness_elements: 1 byte
// - nil_length: 1 byte
// - receiver_sig_length: 1 byte
// - receiver_sig: 73 bytes
// - sender_sig_length: 1 byte
// - sender_sig: 73 bytes
// - payment_preimage_length: 1 byte
// - payment_preimage: 32 bytes
// - witness_script_length: 1 byte
// - witness_script (offered_htlc_script)
OfferedHtlcSuccessWitnessSize = 1 + 1 + 1 + 73 + 1 + 73 + 1 + 32 + 1 + OfferedHtlcScriptSize
// OfferedHtlcPenaltyWitnessSize 243 bytes
// - number_of_witness_elements: 1 byte
// - revocation_sig_length: 1 byte
// - revocation_sig: 73 bytes
// - revocation_key_length: 1 byte
// - revocation_key: 33 bytes
// - witness_script_length: 1 byte
// - witness_script (offered_htlc_script)
OfferedHtlcPenaltyWitnessSize = 1 + 1 + 73 + 1 + 33 + 1 + OfferedHtlcScriptSize
)
// EstimateCommitTxWeight estimate commitment transaction weight depending on
// the precalculated weight of base transaction, witness data, which is needed
// for paying for funding tx, and htlc weight multiplied by their count.
func EstimateCommitTxWeight(count int, prediction bool) int64 {
// Make prediction about the size of commitment transaction with
// additional HTLC.
if prediction {
count++
}
htlcWeight := int64(count * HTLCWeight)
baseWeight := int64(BaseCommitmentTxWeight)
witnessWeight := int64(WitnessCommitmentTxWeight)
return htlcWeight + baseWeight + witnessWeight
}
// TxWeightEstimator is able to calculate weight estimates for transactions
// based on the input and output types. For purposes of estimation, all
// signatures are assumed to be of the maximum possible size, 73 bytes. Each
// method of the estimator returns an instance with the estimate applied. This
// allows callers to chain each of the methods
type TxWeightEstimator struct {
hasWitness bool
inputCount uint32
outputCount uint32
inputSize int
inputWitnessSize int
outputSize int
}
// AddP2PKHInput updates the weight estimate to account for an additional input
// spending a P2PKH output.
func (twe *TxWeightEstimator) AddP2PKHInput() *TxWeightEstimator {
twe.inputSize += InputSize + P2PKHScriptSigSize
twe.inputWitnessSize++
twe.inputCount++
return twe
}
// AddP2WKHInput updates the weight estimate to account for an additional input
// spending a native P2PWKH output.
func (twe *TxWeightEstimator) AddP2WKHInput() *TxWeightEstimator {
twe.AddWitnessInput(P2WKHWitnessSize)
return twe
}
// AddWitnessInput updates the weight estimate to account for an additional
// input spending a native pay-to-witness output. This accepts the total size
// of the witness as a parameter.
func (twe *TxWeightEstimator) AddWitnessInput(witnessSize int) *TxWeightEstimator {
twe.inputSize += InputSize
twe.inputWitnessSize += witnessSize
twe.inputCount++
twe.hasWitness = true
return twe
}
// AddNestedP2WKHInput updates the weight estimate to account for an additional
// input spending a P2SH output with a nested P2WKH redeem script.
func (twe *TxWeightEstimator) AddNestedP2WKHInput() *TxWeightEstimator {
twe.inputSize += InputSize + P2WPKHSize
twe.inputWitnessSize += P2WKHWitnessSize
twe.inputSize++
twe.hasWitness = true
return twe
}
// AddNestedP2WSHInput updates the weight estimate to account for an additional
// input spending a P2SH output with a nested P2WSH redeem script.
func (twe *TxWeightEstimator) AddNestedP2WSHInput(witnessSize int) *TxWeightEstimator {
twe.inputSize += InputSize + P2WSHSize
twe.inputWitnessSize += witnessSize
twe.inputSize++
twe.hasWitness = true
return twe
}
// AddP2PKHOutput updates the weight estimate to account for an additional P2PKH
// output.
func (twe *TxWeightEstimator) AddP2PKHOutput() *TxWeightEstimator {
twe.outputSize += P2PKHOutputSize
twe.outputCount++
return twe
}
// AddP2WKHOutput updates the weight estimate to account for an additional
// native P2WKH output.
func (twe *TxWeightEstimator) AddP2WKHOutput() *TxWeightEstimator {
twe.outputSize += P2WKHOutputSize
twe.outputCount++
return twe
}
// AddP2WSHOutput updates the weight estimate to account for an additional
// native P2WSH output.
func (twe *TxWeightEstimator) AddP2WSHOutput() *TxWeightEstimator {
twe.outputSize += P2WSHOutputSize
twe.outputCount++
return twe
}
// AddP2SHOutput updates the weight estimate to account for an additional P2SH
// output.
func (twe *TxWeightEstimator) AddP2SHOutput() *TxWeightEstimator {
twe.outputSize += P2SHOutputSize
twe.outputCount++
return twe
}
// Weight gets the estimated weight of the transaction.
func (twe *TxWeightEstimator) Weight() int {
txSizeStripped := BaseTxSize +
wire.VarIntSerializeSize(uint64(twe.inputCount)) + twe.inputSize +
wire.VarIntSerializeSize(uint64(twe.outputCount)) + twe.outputSize
weight := txSizeStripped * witnessScaleFactor
if twe.hasWitness {
weight += WitnessHeaderSize + twe.inputWitnessSize
}
return weight
}
// VSize gets the estimated virtual size of the transactions, in vbytes.
func (twe *TxWeightEstimator) VSize() int {
// A tx's vsize is 1/4 of the weight, rounded up.
return (twe.Weight() + witnessScaleFactor - 1) / witnessScaleFactor
}