427 lines
14 KiB
Go
427 lines
14 KiB
Go
package lnwallet
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import (
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"github.com/roasbeef/btcd/blockchain"
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"github.com/roasbeef/btcd/wire"
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)
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const (
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// CommitWeight is the weight of the base commitment transaction which
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// includes: one p2wsh input, out p2wkh output, and one p2wsh output.
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CommitWeight int64 = 724
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// HtlcWeight is the weight of an HTLC output.
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HtlcWeight int64 = 172
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)
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const (
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// witnessScaleFactor determines the level of "discount" witness data
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// receives compared to "base" data. A scale factor of 4, denotes that
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// witness data is 1/4 as cheap as regular non-witness data. Value copied
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// here for convenience.
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witnessScaleFactor = blockchain.WitnessScaleFactor
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// The weight(weight), which is different from the !size! (see BIP-141),
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// is calculated as:
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// Weight = 4 * BaseSize + WitnessSize (weight).
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// BaseSize - size of the transaction without witness data (bytes).
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// WitnessSize - witness size (bytes).
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// Weight - the metric for determining the weight of the transaction.
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// P2WPKHSize 22 bytes
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// - OP_0: 1 byte
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// - OP_DATA: 1 byte (PublicKeyHASH160 length)
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// - PublicKeyHASH160: 20 bytes
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P2WPKHSize = 1 + 1 + 20
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// P2WSHSize 34 bytes
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// - OP_0: 1 byte
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// - OP_DATA: 1 byte (WitnessScriptSHA256 length)
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// - WitnessScriptSHA256: 32 bytes
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P2WSHSize = 1 + 1 + 32
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// P2PKHOutputSize 34 bytes
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// - value: 8 bytes
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// - var_int: 1 byte (pkscript_length)
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// - pkscript (p2pkh): 25 bytes
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P2PKHOutputSize = 8 + 1 + 25
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// P2WKHOutputSize 31 bytes
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// - value: 8 bytes
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// - var_int: 1 byte (pkscript_length)
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// - pkscript (p2wpkh): 22 bytes
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P2WKHOutputSize = 8 + 1 + P2WPKHSize
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// P2WSHOutputSize 43 bytes
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// - value: 8 bytes
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// - var_int: 1 byte (pkscript_length)
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// - pkscript (p2wsh): 34 bytes
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P2WSHOutputSize = 8 + 1 + P2WSHSize
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// P2SHOutputSize 32 bytes
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// - value: 8 bytes
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// - var_int: 1 byte (pkscript_length)
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// - pkscript (p2sh): 23 bytes
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P2SHOutputSize = 8 + 1 + 23
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// P2PKHScriptSigSize 108 bytes
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// - OP_DATA: 1 byte (signature length)
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// - signature
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// - OP_DATA: 1 byte (pubkey length)
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// - pubkey
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P2PKHScriptSigSize = 1 + 73 + 1 + 33
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// P2WKHWitnessSize 109 bytes
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// - number_of_witness_elements: 1 byte
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// - signature_length: 1 byte
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// - signature
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// - pubkey_length: 1 byte
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// - pubkey
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P2WKHWitnessSize = 1 + 1 + 73 + 1 + 33
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// MultiSigSize 71 bytes
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// - OP_2: 1 byte
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// - OP_DATA: 1 byte (pubKeyAlice length)
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// - pubKeyAlice: 33 bytes
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// - OP_DATA: 1 byte (pubKeyBob length)
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// - pubKeyBob: 33 bytes
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// - OP_2: 1 byte
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// - OP_CHECKMULTISIG: 1 byte
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MultiSigSize = 1 + 1 + 33 + 1 + 33 + 1 + 1
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// WitnessSize 222 bytes
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// - NumberOfWitnessElements: 1 byte
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// - NilLength: 1 byte
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// - sigAliceLength: 1 byte
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// - sigAlice: 73 bytes
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// - sigBobLength: 1 byte
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// - sigBob: 73 bytes
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// - WitnessScriptLength: 1 byte
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// - WitnessScript (MultiSig)
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WitnessSize = 1 + 1 + 1 + 73 + 1 + 73 + 1 + MultiSigSize
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// InputSize 41 bytes
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// - PreviousOutPoint:
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// - Hash: 32 bytes
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// - Index: 4 bytes
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// - OP_DATA: 1 byte (ScriptSigLength)
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// - ScriptSig: 0 bytes
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// - Witness <---- we use "Witness" instead of "ScriptSig" for
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// transaction validation, but "Witness" is stored
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// separately and weight for it size is smaller. So
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// we separate the calculation of ordinary data
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// from witness data.
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// - Sequence: 4 bytes
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InputSize = 32 + 4 + 1 + 4
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// FundingInputSize represents the size of an input to a funding
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// transaction, and is equivalent to the size of a standard segwit input
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// as calculated above.
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FundingInputSize = InputSize
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// CommitmentDelayOutput 43 bytes
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// - Value: 8 bytes
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// - VarInt: 1 byte (PkScript length)
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// - PkScript (P2WSH)
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CommitmentDelayOutput = 8 + 1 + P2WSHSize
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// CommitmentKeyHashOutput 31 bytes
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// - Value: 8 bytes
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// - VarInt: 1 byte (PkScript length)
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// - PkScript (P2WPKH)
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CommitmentKeyHashOutput = 8 + 1 + P2WPKHSize
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// HTLCSize 43 bytes
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// - Value: 8 bytes
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// - VarInt: 1 byte (PkScript length)
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// - PkScript (PW2SH)
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HTLCSize = 8 + 1 + P2WSHSize
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// WitnessHeaderSize 2 bytes
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// - Flag: 1 byte
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// - Marker: 1 byte
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WitnessHeaderSize = 1 + 1
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// BaseTxSize 8 bytes
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// - Version: 4 bytes
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// - LockTime: 4 bytes
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BaseTxSize = 4 + 4
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// BaseCommitmentTxSize 125 + 43 * num-htlc-outputs bytes
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// - Version: 4 bytes
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// - WitnessHeader <---- part of the witness data
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// - CountTxIn: 1 byte
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// - TxIn: 41 bytes
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// FundingInput
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// - CountTxOut: 1 byte
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// - TxOut: 74 + 43 * num-htlc-outputs bytes
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// OutputPayingToThem,
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// OutputPayingToUs,
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// ....HTLCOutputs...
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// - LockTime: 4 bytes
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BaseCommitmentTxSize = 4 + 1 + FundingInputSize + 1 +
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CommitmentDelayOutput + CommitmentKeyHashOutput + 4
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// BaseCommitmentTxWeight 500 weight
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BaseCommitmentTxWeight = witnessScaleFactor * BaseCommitmentTxSize
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// WitnessCommitmentTxWeight 224 weight
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WitnessCommitmentTxWeight = WitnessHeaderSize + WitnessSize
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// HTLCWeight 172 weight
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HTLCWeight = witnessScaleFactor * HTLCSize
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// HtlcTimeoutWeight is the weight of the HTLC timeout transaction
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// which will transition an outgoing HTLC to the delay-and-claim state.
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HtlcTimeoutWeight = 663
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// HtlcSuccessWeight is the weight of the HTLC success transaction
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// which will transition an incoming HTLC to the delay-and-claim state.
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HtlcSuccessWeight = 703
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// MaxHTLCNumber is the maximum number HTLCs which can be included in a
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// commitment transaction. This limit was chosen such that, in the case
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// of a contract breach, the punishment transaction is able to sweep
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// all the HTLC's yet still remain below the widely used standard
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// weight limits.
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MaxHTLCNumber = 966
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// ToLocalPenaltyScriptSize 83 bytes
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// - OP_IF: 1 byte
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// - OP_DATA: 1 byte (revocationkey length)
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// - revocationkey: 33 bytes
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// - OP_CHECKSIG: 1 byte
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// - OP_ELSE: 1 byte
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// - OP_DATA: 1 byte (localkey length)
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// - localkey: 33 bytes
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// - OP_CHECKSIG_VERIFY: 1 byte
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// - OP_DATA: 1 byte (delay length)
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// - delay: 8 bytes
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// -OP_CHECKSEQUENCEVERIFY: 1 byte
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// - OP_ENDIF: 1 byte
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ToLocalPenaltyScriptSize = 1 + 1 + 33 + 1 + 1 + 1 + 33 + 1 + 1 + 8 + 1 + 1
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// ToLocalPenaltyWitnessSize 160 bytes
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// - number_of_witness_elements: 1 byte
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// - revocation_sig_length: 1 byte
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// - revocation_sig: 73 bytes
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// - one_length: 1 byte
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// - witness_script_length: 1 byte
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// - witness_script (to_local_script)
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ToLocalPenaltyWitnessSize = 1 + 1 + 73 + 1 + 1 + ToLocalPenaltyScriptSize
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// AcceptedHtlcPenaltyScriptSize 139 bytes
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// - OP_DUP: 1 byte
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// - OP_HASH160: 1 byte
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// - OP_DATA: 1 byte (RIPEMD160(SHA256(revocationkey)) length)
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// - RIPEMD160(SHA256(revocationkey)): 20 bytes
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// - OP_EQUAL: 1 byte
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// - OP_IF: 1 byte
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// - OP_CHECKSIG: 1 byte
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// - OP_ELSE: 1 byte
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// - OP_DATA: 1 byte (remotekey length)
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// - remotekey: 33 bytes
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// - OP_SWAP: 1 byte
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// - OP_SIZE: 1 byte
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// - 32: 1 byte
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// - OP_EQUAL: 1 byte
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// - OP_IF: 1 byte
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// - OP_HASH160: 1 byte
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// - OP_DATA: 1 byte (RIPEMD160(payment_hash) length)
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// - RIPEMD160(payment_hash): 20 bytes
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// - OP_EQUALVERIFY: 1 byte
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// - 2: 1 byte
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// - OP_SWAP: 1 byte
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// - OP_DATA: 1 byte (localkey length)
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// - localkey: 33 bytes
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// - 2: 1 byte
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// - OP_CHECKMULTISIG: 1 byte
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// - OP_ELSE: 1 byte
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// - OP_DROP: 1 byte
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// - OP_DATA: 1 byte (cltv_expiry length)
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// - cltv_expiry: 4 bytes
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// - OP_CHECKLOCKTIMEVERIFY: 1 byte
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// - OP_DROP: 1 byte
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// - OP_CHECKSIG: 1 byte
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// - OP_ENDIF: 1 byte
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// - OP_ENDIF: 1 byte
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AcceptedHtlcPenaltyScriptSize = 3*1 + 20 + 5*1 + 33 + 7*1 + 20 + 4*1 +
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33 + 5*1 + 4 + 5*1
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// AcceptedHtlcPenaltyWitnessSize 249 bytes
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// - number_of_witness_elements: 1 byte
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// - revocation_sig_length: 1 byte
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// - revocation_sig: 73 bytes
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// - revocation_key_length: 1 byte
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// - revocation_key: 33 bytes
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// - witness_script_length: 1 byte
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// - witness_script (accepted_htlc_script)
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AcceptedHtlcPenaltyWitnessSize = 1 + 1 + 73 + 1 + 33 + 1 +
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AcceptedHtlcPenaltyScriptSize
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// OfferedHtlcScriptSize 133 bytes
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// - OP_DUP: 1 byte
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// - OP_HASH160: 1 byte
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// - OP_DATA: 1 byte (RIPEMD160(SHA256(revocationkey)) length)
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// - RIPEMD160(SHA256(revocationkey)): 20 bytes
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// - OP_EQUAL: 1 byte
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// - OP_IF: 1 byte
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// - OP_CHECKSIG: 1 byte
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// - OP_ELSE: 1 byte
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// - OP_DATA: 1 byte (remotekey length)
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// - remotekey: 33 bytes
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// - OP_SWAP: 1 byte
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// - OP_SIZE: 1 byte
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// - OP_DATA: 1 byte (32 length)
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// - 32: 1 byte
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// - OP_EQUAL: 1 byte
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// - OP_NOTIF: 1 byte
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// - OP_DROP: 1 byte
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// - 2: 1 byte
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// - OP_SWAP: 1 byte
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// - OP_DATA: 1 byte (localkey length)
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// - localkey: 33 bytes
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// - 2: 1 byte
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// - OP_CHECKMULTISIG: 1 byte
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// - OP_ELSE: 1 byte
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// - OP_HASH160: 1 byte
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// - OP_DATA: 1 byte (RIPEMD160(payment_hash) length)
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// - RIPEMD160(payment_hash): 20 bytes
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// - OP_EQUALVERIFY: 1 byte
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// - OP_CHECKSIG: 1 byte
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// - OP_ENDIF: 1 byte
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// - OP_ENDIF: 1 byte
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OfferedHtlcScriptSize = 3*1 + 20 + 5*1 + 33 + 10*1 + 33 + 5*1 + 20 + 4*1
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// OfferedHtlcWitnessSize 243 bytes
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// - number_of_witness_elements: 1 byte
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// - revocation_sig_length: 1 byte
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// - revocation_sig: 73 bytes
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// - revocation_key_length: 1 byte
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// - revocation_key: 33 bytes
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// - witness_script_length: 1 byte
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// - witness_script (offered_htlc_script)
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OfferedHtlcWitnessSize = 1 + 1 + 73 + 1 + 33 + 1 + OfferedHtlcScriptSize
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// OfferedHtlcPenaltyWitnessSize 243 bytes
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// - number_of_witness_elements: 1 byte
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// - revocation_sig_length: 1 byte
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// - revocation_sig: 73 bytes
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// - revocation_key_length: 1 byte
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// - revocation_key: 33 bytes
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// - witness_script_length: 1 byte
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// - witness_script (offered_htlc_script)
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OfferedHtlcPenaltyWitnessSize = 1 + 1 + 73 + 1 + 1 + OfferedHtlcScriptSize
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)
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// estimateCommitTxWeight estimate commitment transaction weight depending on
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// the precalculated weight of base transaction, witness data, which is needed
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// for paying for funding tx, and htlc weight multiplied by their count.
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func estimateCommitTxWeight(count int, prediction bool) int64 {
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// Make prediction about the size of commitment transaction with
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// additional HTLC.
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if prediction {
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count++
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}
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htlcWeight := int64(count * HTLCWeight)
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baseWeight := int64(BaseCommitmentTxWeight)
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witnessWeight := int64(WitnessCommitmentTxWeight)
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return htlcWeight + baseWeight + witnessWeight
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}
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// TxWeightEstimator is able to calculate weight estimates for transactions
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// based on the input and output types. For purposes of estimation, all
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// signatures are assumed to be of the maximum possible size, 73 bytes.
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type TxWeightEstimator struct {
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hasWitness bool
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inputCount uint32
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outputCount uint32
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inputSize int
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inputWitnessSize int
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outputSize int
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}
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// AddP2PKHInput updates the weight estimate to account for an additional input
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// spending a P2PKH output.
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func (twe *TxWeightEstimator) AddP2PKHInput() {
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twe.inputSize += InputSize + P2PKHScriptSigSize
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twe.inputWitnessSize++
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twe.inputCount++
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}
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// AddP2WKHInput updates the weight estimate to account for an additional input
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// spending a native P2PWKH output.
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func (twe *TxWeightEstimator) AddP2WKHInput() {
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twe.AddWitnessInput(P2WKHWitnessSize)
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}
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// AddWitnessInput updates the weight estimate to account for an additional
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// input spending a native pay-to-witness output. This accepts the total size
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// of the witness as a parameter.
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func (twe *TxWeightEstimator) AddWitnessInput(witnessSize int) {
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twe.inputSize += InputSize
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twe.inputWitnessSize += witnessSize
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twe.inputCount++
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twe.hasWitness = true
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}
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// AddNestedP2WKHInput updates the weight estimate to account for an additional
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// input spending a P2SH output with a nested P2WKH redeem script.
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func (twe *TxWeightEstimator) AddNestedP2WKHInput() {
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twe.inputSize += InputSize + P2WPKHSize
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twe.inputWitnessSize += P2WKHWitnessSize
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twe.inputSize++
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twe.hasWitness = true
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}
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// AddNestedP2WSHInput updates the weight estimate to account for an additional
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// input spending a P2SH output with a nested P2WSH redeem script.
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func (twe *TxWeightEstimator) AddNestedP2WSHInput(witnessSize int) {
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twe.inputSize += InputSize + P2WSHSize
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twe.inputWitnessSize += witnessSize
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twe.inputSize++
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twe.hasWitness = true
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}
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// AddP2PKHOutput updates the weight estimate to account for an additional P2PKH
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// output.
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func (twe *TxWeightEstimator) AddP2PKHOutput() {
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twe.outputSize += P2PKHOutputSize
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twe.outputCount++
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}
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// AddP2WKHOutput updates the weight estimate to account for an additional
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// native P2WKH output.
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func (twe *TxWeightEstimator) AddP2WKHOutput() {
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twe.outputSize += P2WKHOutputSize
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twe.outputCount++
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}
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// AddP2WSHOutput updates the weight estimate to account for an additional
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// native P2WSH output.
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func (twe *TxWeightEstimator) AddP2WSHOutput() {
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twe.outputSize += P2WSHOutputSize
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twe.outputCount++
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}
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// AddP2SHOutput updates the weight estimate to account for an additional P2SH
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// output.
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func (twe *TxWeightEstimator) AddP2SHOutput() {
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twe.outputSize += P2SHOutputSize
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twe.outputCount++
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}
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// Weight gets the estimated weight of the transaction.
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func (twe *TxWeightEstimator) Weight() int {
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txSizeStripped := BaseTxSize +
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wire.VarIntSerializeSize(uint64(twe.inputCount)) + twe.inputSize +
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wire.VarIntSerializeSize(uint64(twe.outputCount)) + twe.outputSize
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weight := txSizeStripped * witnessScaleFactor
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if twe.hasWitness {
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weight += WitnessHeaderSize + twe.inputWitnessSize
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}
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return weight
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}
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