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descriptors: add method to get max tx weight

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Errors in the weight calculation could be hidden when converting
to vbytes. This separate method will make it easier to spot any
such errors.
This commit is contained in:
Michael Mallan 2024-11-08 17:23:08 +00:00
parent 327f0ea665
commit 03a3230a67
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GPG Key ID: 5177CDCEDB0EABEB
1 changed files with 14 additions and 9 deletions
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23
liana/src/descriptors/mod.rs
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@ -545,20 +545,25 @@ impl LianaDescriptor {
Ok(self.prune_bip32_derivs(psbt, path_info))
}
/// Maximum possible weight in weight units of an unsigned transaction, `tx`,
/// after satisfaction, assuming all inputs of `tx` are from this
/// descriptor.
fn unsigned_tx_max_weight(&self, tx: &bitcoin::Transaction, use_primary_path: bool) -> u64 {
let num_inputs: u64 = tx.input.len().try_into().unwrap();
let max_sat_weight: u64 = self.max_sat_weight(use_primary_path).try_into().unwrap();
// Add weights together before converting to vbytes to avoid rounding up multiple times.
tx.weight()
.to_wu()
.checked_add(max_sat_weight.checked_mul(num_inputs).unwrap())
.unwrap()
}
/// Maximum possible size in vbytes of an unsigned transaction, `tx`,
/// after satisfaction, assuming all inputs of `tx` are from this
/// descriptor.
pub fn unsigned_tx_max_vbytes(&self, tx: &bitcoin::Transaction, use_primary_path: bool) -> u64 {
let witness_factor: u64 = WITNESS_SCALE_FACTOR.try_into().unwrap();
let num_inputs: u64 = tx.input.len().try_into().unwrap();
let max_sat_weight: u64 = self.max_sat_weight(use_primary_path).try_into().unwrap();
// Add weights together before converting to vbytes to avoid rounding up multiple times.
let tx_wu = tx
.weight()
.to_wu()
.checked_add(max_sat_weight.checked_mul(num_inputs).unwrap())
.unwrap();
tx_wu
self.unsigned_tx_max_weight(tx, use_primary_path)
.checked_add(witness_factor.checked_sub(1).unwrap())
.unwrap()
.checked_div(witness_factor)