136 lines
3.9 KiB
Go
136 lines
3.9 KiB
Go
package lnwallet
|
|
|
|
import (
|
|
"github.com/roasbeef/btcd/blockchain"
|
|
)
|
|
|
|
const (
|
|
WitnessFactor = blockchain.WitnessScaleFactor
|
|
MaxTransactionWeightPolicy = blockchain.MaxBlockCost / 10
|
|
|
|
// The weight(cost), 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 cost of the transaction.
|
|
|
|
// P2WSH: 34 bytes
|
|
// - OP_0: 1 byte
|
|
// - OP_DATA: 1 byte (WitnessScriptSHA256 length)
|
|
// - WitnessScriptSHA256: 32 bytes
|
|
P2WSHSize = 1 + 1 + 32
|
|
|
|
// P2PKH: 22 bytes
|
|
// - OP_0: 1 byte
|
|
// - OP_DATA: 1 byte (PublicKeyHASH160 length)
|
|
// - PublicKeyHASH160: 20 bytes
|
|
P2WPKHSize = 1 + 1 + 20
|
|
|
|
// MultiSig: 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
|
|
|
|
// Witness: 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
|
|
|
|
// FundingInput: 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 cost for it size is smaller. So
|
|
// we separate the calculation of ordinary data
|
|
// from witness data.
|
|
// - Sequence: 4 bytes
|
|
FundingInputSize = 32 + 4 + 1 + 4
|
|
|
|
// OutputPayingToUs: 43 bytes
|
|
// - Value: 8 bytes
|
|
// - VarInt: 1 byte (PkScript length)
|
|
// - PkScript (P2WSH)
|
|
CommitmentDelayOutput = 8 + 1 + P2WSHSize
|
|
|
|
// OutputPayingToThem: 31 bytes
|
|
// - Value: 8 bytes
|
|
// - VarInt: 1 byte (PkScript length)
|
|
// - PkScript (P2WPKH)
|
|
CommitmentKeyHashOutput = 8 + 1 + P2WPKHSize
|
|
|
|
// HTLCOutput: 43 bytes
|
|
// - Value: 8 bytes
|
|
// - VarInt: 1 byte (PkScript length)
|
|
// - PkScript (PW2SH)
|
|
HTLCSize = 8 + 1 + P2WSHSize
|
|
|
|
// WitnessHeader: 2 bytes
|
|
// - Flag: 1 byte
|
|
// - Marker: 1 byte
|
|
WitnessHeaderSize = 1 + 1
|
|
|
|
// CommitmentTransaction: 125 bytes
|
|
// - Version: 4 bytes
|
|
// - WitnessHeader <---- part of the witness data
|
|
// - CountTxIn: 1 byte
|
|
// - TxIn:
|
|
// FundingInput
|
|
// - CountTxOut: 1 byte
|
|
// - TxOut:
|
|
// OutputPayingToThem,
|
|
// OutputPayingToUs,
|
|
// ....HTLCOutputs...
|
|
// - LockTime: 4 bytes
|
|
BaseCommitmentTxSize = 4 + 1 + FundingInputSize + 1 +
|
|
CommitmentDelayOutput + CommitmentKeyHashOutput + 4
|
|
|
|
// CommitmentTransactionCost: 500 weight
|
|
BaseCommitmentTxCost = WitnessFactor * BaseCommitmentTxSize
|
|
|
|
// WitnessCommitmentTxCost: 224 weight
|
|
WitnessCommitmentTxCost = WitnessHeaderSize + WitnessSize
|
|
|
|
// HTLCCost: 172 weight
|
|
HTLCCost = WitnessFactor * HTLCSize
|
|
|
|
// MaxHTLCNumber shows as the maximum number HTLCs which can be
|
|
// included in commitment transaction. This numbers was calculated by
|
|
// Rusty Russel in "BOLT #5: Recommendations for On-chain Transaction
|
|
// Handling", based on the fact that we need to sweep all HTLCs within
|
|
// one penalty transaction.
|
|
MaxHTLCNumber = 1253
|
|
)
|
|
|
|
|
|
// estimateCommitTxCost estimate commitment transaction cost depending on the
|
|
// precalculated cost of base transaction, witness data, which is needed for
|
|
// paying for funding tx, and htlc cost multiplied by their count.
|
|
func estimateCommitTxCost(count int, prediction bool) int64 {
|
|
// Make prediction about the size of commitment transaction with
|
|
// additional HTLC.
|
|
if prediction {
|
|
count++
|
|
}
|
|
|
|
htlcCost := int64(count * HTLCCost)
|
|
baseCost := int64(BaseCommitmentTxCost)
|
|
witnessCost := int64(WitnessCommitmentTxCost)
|
|
|
|
return htlcCost + baseCost + witnessCost
|
|
} |