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spend: add 10 sats to fee for 1 sat/vb txs

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This is a quick change to prevent the fee being below the
min relay fee.
This commit is contained in:
Michael Mallan 2024-09-11 15:01:50 +01:00
parent 2a407013e3
commit 74a53baa39
No known key found for this signature in database
GPG Key ID: 5177CDCEDB0EABEB
3 changed files with 25 additions and 12 deletions
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18
src/commands/mod.rs
View File

@ -1494,7 +1494,7 @@ mod tests {
// Transaction is 1 in (P2WSH satisfaction), 2 outs. At 1sat/vb, it's 161 sats fees.
// At 2sats/vb, it's twice that.
assert_eq!(tx.output[1].value.to_sat(), 89_839);
assert_eq!(tx.output[1].value.to_sat(), 89_829);
let psbt = if let CreateSpendResult::Success { psbt, .. } = control
.create_spend(&destinations, &[dummy_op], 2, None)
.unwrap()
@ -1562,18 +1562,18 @@ mod tests {
dummy_addr.payload().script_pubkey()
);
assert_eq!(tx.output[0].value.to_sat(), 95_000);
// change = 100_000 - 95_000 - /* fee without change */ 127 - /* extra fee for change output */ 43 = 4830
// change = 100_000 - 95_000 - /* fee without change */ 128 - /* extra fee for change output */ 43 = 4829
assert_eq!(
warnings,
vec![
"Dust UTXO. The minimal change output allowed by Liana is 5000 sats. \
Instead of creating a change of 4839 sats, it was added to the \
Instead of creating a change of 4829 sats, it was added to the \
transaction fee. Select a larger input to avoid this from happening."
]
);
// Increase the target value by the change amount and the warning will disappear.
*destinations.get_mut(&dummy_addr).unwrap() = 95_000 + 4_839;
*destinations.get_mut(&dummy_addr).unwrap() = 95_000 + 4_829;
let (psbt, warnings) = if let CreateSpendResult::Success { psbt, warnings } = control
.create_spend(&destinations, &[dummy_op], 1, None)
.unwrap()
@ -1588,7 +1588,7 @@ mod tests {
// Now increase target also by the extra fee that was paying for change and we can still create the spend.
*destinations.get_mut(&dummy_addr).unwrap() =
95_000 + 4_830 + /* fee for change output */ 43;
95_000 + 4_829 + /* fee for change output */ 43;
let (psbt, warnings) = if let CreateSpendResult::Success { psbt, warnings } = control
.create_spend(&destinations, &[dummy_op], 1, None)
.unwrap()
@ -1603,7 +1603,7 @@ mod tests {
// Now increase the target by 1 more sat and we will have insufficient funds.
*destinations.get_mut(&dummy_addr).unwrap() =
95_000 + 4_839 + /* fee for change output */ 43 + 1;
95_000 + 4_829 + /* fee for change output */ 43 + 1;
assert_eq!(
control.create_spend(&destinations, &[dummy_op], 1, None),
Ok(CreateSpendResult::InsufficientFunds { missing: 1 }),
@ -1611,7 +1611,7 @@ mod tests {
// Now decrease the target so that the lost change is just 1 sat.
*destinations.get_mut(&dummy_addr).unwrap() =
100_000 - /* fee without change */ 118 - /* extra fee for change output */ 43 - 1;
100_000 - /* fee without change */ 128 - /* extra fee for change output */ 43 - 1;
let warnings = if let CreateSpendResult::Success { warnings, .. } = control
.create_spend(&destinations, &[dummy_op], 1, None)
.unwrap()
@ -1632,7 +1632,7 @@ mod tests {
// Now decrease the target value so that we have enough for a change output.
*destinations.get_mut(&dummy_addr).unwrap() =
95_000 - /* fee without change */ 118 - /* extra fee for change output */ 43;
95_000 - /* fee without change */ 128 - /* extra fee for change output */ 43;
let (psbt, warnings) = if let CreateSpendResult::Success { psbt, warnings } = control
.create_spend(&destinations, &[dummy_op], 1, None)
.unwrap()
@ -1648,7 +1648,7 @@ mod tests {
// Now increase the target by 1 and we'll get a warning again, this time for 1 less than the dust threshold.
*destinations.get_mut(&dummy_addr).unwrap() =
95_000 - /* fee without change */ 118 - /* extra fee for change output */ 43 + 1;
95_000 - /* fee without change */ 128 - /* extra fee for change output */ 43 + 1;
let warnings = if let CreateSpendResult::Success { warnings, .. } = control
.create_spend(&destinations, &[dummy_op], 1, None)
.unwrap()

15
src/spend.rs
View File

@ -12,6 +12,7 @@ use bdk_coin_select::{
metrics::LowestFee, Candidate, ChangePolicy, CoinSelector, DrainWeights, FeeRate, Replace,
Target, TargetFee, TargetOutputs, TXIN_BASE_WEIGHT,
};
use log::info;
use miniscript::bitcoin::{
self,
absolute::{Height, LockTime},
@ -384,9 +385,21 @@ fn select_coins_for_spend(
long_term_feerate,
);
// FIXME: This is a quick change to avoid going below the min relay fee:
// If the required feerate is 1 sat/vb and this is not a replacement tx,
// use the replaced_fee parameter to ensure we pay at least 10 sats more
// than the size of the tx.
// E.g. if vsize = 186, the fee will be pay >= 196 sats.
let replaced_fee_modified = if replaced_fee.is_none() && feerate_vb_u32 == 1 {
info!("setting replaced fee to 10");
Some(10)
} else {
replaced_fee
};
// Finally, run the coin selection algorithm. We use an opportunistic BnB and if it couldn't
// find any solution we fall back to selecting coins by descending value.
let replace = replaced_fee.map(Replace::new);
let replace = replaced_fee_modified.map(Replace::new);
let target_fee = TargetFee {
rate: feerate,
replace,

4
tests/test_spend.py
View File

@ -134,7 +134,7 @@ def test_coin_marked_spent(lianad, bitcoind):
res = lianad.rpc.createspend(destinations, [outpoint], 1)
psbt = PSBT.from_base64(res["psbt"])
sign_and_broadcast(psbt)
change_amount = 858 if USE_TAPROOT else 839
change_amount = 848 if USE_TAPROOT else 829
assert len(psbt.o) == 1
assert len(res["warnings"]) == 1
assert (
@ -153,7 +153,7 @@ def test_coin_marked_spent(lianad, bitcoind):
res = lianad.rpc.createspend(destinations, [outpoint_3], 1)
psbt = PSBT.from_base64(res["psbt"])
sign_and_broadcast(psbt)
change_amount = 846 if USE_TAPROOT else 827
change_amount = 836 if USE_TAPROOT else 817
assert len(psbt.o) == 1
assert len(res["warnings"]) == 1
assert (