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input/size: correct NP2WKH and NP2SH input count

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This commit corrects a bug in TxWeightEstimator that could result in
underestimations for transactions involving NestedP2WPKH and NestedP2WSH
inputs. The scriptSig data push is now accounted for in a proper size
constant, and the input count is now incremented in both. This would
only be detectable in the event that the number of non-nested inputs and
the total number of inputs straddle the discontinuities in the
CompactSize encoding, e.g. 253, 2^16-1, or 2^32-1.
This commit is contained in:
Conner Fromknecht 2020-03-04 08:00:33 -08:00
parent be74d94c48
commit 6eb7f2800d
No known key found for this signature in database
GPG Key ID: E7D737B67FA592C7
1 changed files with 14 additions and 4 deletions
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18
input/size.go
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@ -25,12 +25,22 @@ const (
// - PublicKeyHASH160: 20 bytes
P2WPKHSize = 1 + 1 + 20
// NestedP2WPKHSize 23 bytes
// - OP_DATA: 1 byte (P2WPKHSize)
// - P2WPKHWitnessProgram: 22 bytes
NestedP2WPKHSize = 1 + P2WPKHSize
// P2WSHSize 34 bytes
// - OP_0: 1 byte
// - OP_DATA: 1 byte (WitnessScriptSHA256 length)
// - WitnessScriptSHA256: 32 bytes
P2WSHSize = 1 + 1 + 32
// NestedP2WSHSize 35 bytes
// - OP_DATA: 1 byte (P2WSHSize)
// - P2WSHWitnessProgram: 35 bytes
NestedP2WSHSize = 1 + P2WSHSize
// P2PKHOutputSize 34 bytes
// - value: 8 bytes
// - var_int: 1 byte (pkscript_length)
@ -417,9 +427,9 @@ func (twe *TxWeightEstimator) AddWitnessInput(witnessSize int) *TxWeightEstimato
// 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.inputSize += InputSize + NestedP2WPKHSize
twe.inputWitnessSize += P2WKHWitnessSize
twe.inputSize++
twe.inputCount++
twe.hasWitness = true
return twe
@ -428,9 +438,9 @@ func (twe *TxWeightEstimator) AddNestedP2WKHInput() *TxWeightEstimator {
// 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.inputSize += InputSize + NestedP2WSHSize
twe.inputWitnessSize += witnessSize
twe.inputSize++
twe.inputCount++
twe.hasWitness = true
return twe