let mut anchor_utxo = anchor_descriptor.previous_utxo();
let commitment_tx_fee_sat = Amount::from_sat(commitment_tx_fee_sat);
anchor_utxo.value += commitment_tx_fee_sat;
- let must_spend = vec![Input {
- outpoint: anchor_descriptor.outpoint,
- previous_utxo: anchor_utxo,
- satisfaction_weight: commitment_tx.weight().to_wu() + ANCHOR_INPUT_WITNESS_WEIGHT + EMPTY_SCRIPT_SIG_WEIGHT,
- }];
- #[cfg(debug_assertions)]
- let must_spend_amount = must_spend.iter().map(|input| input.previous_utxo.value).sum::<Amount>();
-
- log_debug!(self.logger, "Performing coin selection for commitment package (commitment and anchor transaction) targeting {} sat/kW",
- package_target_feerate_sat_per_1000_weight);
- let coin_selection: CoinSelection = self.utxo_source.select_confirmed_utxos(
- claim_id, must_spend, &[], package_target_feerate_sat_per_1000_weight,
- )?;
-
- let mut anchor_tx = Transaction {
- version: Version::TWO,
- lock_time: LockTime::ZERO, // TODO: Use next best height.
- input: vec![anchor_descriptor.unsigned_tx_input()],
- output: vec![],
- };
-
- #[cfg(debug_assertions)]
- let total_satisfaction_weight = ANCHOR_INPUT_WITNESS_WEIGHT + EMPTY_SCRIPT_SIG_WEIGHT +
- coin_selection.confirmed_utxos.iter().map(|utxo| utxo.satisfaction_weight).sum::<u64>();
- #[cfg(debug_assertions)]
- let total_input_amount = must_spend_amount +
- coin_selection.confirmed_utxos.iter().map(|utxo| utxo.output.value).sum();
-
- self.process_coin_selection(&mut anchor_tx, &coin_selection);
- let anchor_txid = anchor_tx.compute_txid();
+ let starting_package_and_fixed_input_satisfaction_weight =
+ commitment_tx.weight().to_wu() + ANCHOR_INPUT_WITNESS_WEIGHT + EMPTY_SCRIPT_SIG_WEIGHT;
+ let mut package_and_fixed_input_satisfaction_weight =
+ starting_package_and_fixed_input_satisfaction_weight;
+
+ loop {
+ let must_spend = vec![Input {
+ outpoint: anchor_descriptor.outpoint,
+ previous_utxo: anchor_utxo.clone(),
+ satisfaction_weight: package_and_fixed_input_satisfaction_weight,
+ }];
+ let must_spend_amount = must_spend.iter().map(|input| input.previous_utxo.value).sum::<Amount>();
+
+ log_debug!(self.logger, "Performing coin selection for commitment package (commitment and anchor transaction) targeting {} sat/kW",
+ package_target_feerate_sat_per_1000_weight);
+ let coin_selection: CoinSelection = self.utxo_source.select_confirmed_utxos(
+ claim_id, must_spend, &[], package_target_feerate_sat_per_1000_weight,
+ )?;
+
+ let mut anchor_tx = Transaction {
+ version: Version::TWO,
+ lock_time: LockTime::ZERO, // TODO: Use next best height.
+ input: vec![anchor_descriptor.unsigned_tx_input()],
+ output: vec![],
+ };
- // construct psbt
- let mut anchor_psbt = Psbt::from_unsigned_tx(anchor_tx).unwrap();
- // add witness_utxo to anchor input
- anchor_psbt.inputs[0].witness_utxo = Some(anchor_descriptor.previous_utxo());
- // add witness_utxo to remaining inputs
- for (idx, utxo) in coin_selection.confirmed_utxos.into_iter().enumerate() {
- // add 1 to skip the anchor input
- let index = idx + 1;
- debug_assert_eq!(anchor_psbt.unsigned_tx.input[index].previous_output, utxo.outpoint);
- if utxo.output.script_pubkey.is_witness_program() {
- anchor_psbt.inputs[index].witness_utxo = Some(utxo.output);
+ let total_satisfaction_weight = ANCHOR_INPUT_WITNESS_WEIGHT + EMPTY_SCRIPT_SIG_WEIGHT +
+ coin_selection.confirmed_utxos.iter().map(|utxo| utxo.satisfaction_weight).sum::<u64>();
+ let total_input_amount = must_spend_amount +
+ coin_selection.confirmed_utxos.iter().map(|utxo| utxo.output.value).sum();
+
+ self.process_coin_selection(&mut anchor_tx, &coin_selection);
+ let anchor_txid = anchor_tx.compute_txid();
+
+ // construct psbt
+ let mut anchor_psbt = Psbt::from_unsigned_tx(anchor_tx).unwrap();
+ // add witness_utxo to anchor input
+ anchor_psbt.inputs[0].witness_utxo = Some(anchor_descriptor.previous_utxo());
+ // add witness_utxo to remaining inputs
+ for (idx, utxo) in coin_selection.confirmed_utxos.into_iter().enumerate() {
+ // add 1 to skip the anchor input
+ let index = idx + 1;
+ debug_assert_eq!(anchor_psbt.unsigned_tx.input[index].previous_output, utxo.outpoint);
+ if utxo.output.script_pubkey.is_witness_program() {
+ anchor_psbt.inputs[index].witness_utxo = Some(utxo.output);
+ }
}
- }
-
- debug_assert_eq!(anchor_psbt.unsigned_tx.output.len(), 1);
- #[cfg(debug_assertions)]
- let unsigned_tx_weight = anchor_psbt.unsigned_tx.weight().to_wu() - (anchor_psbt.unsigned_tx.input.len() as u64 * EMPTY_SCRIPT_SIG_WEIGHT);
- log_debug!(self.logger, "Signing anchor transaction {}", anchor_txid);
- anchor_tx = self.utxo_source.sign_psbt(anchor_psbt)?;
+ debug_assert_eq!(anchor_psbt.unsigned_tx.output.len(), 1);
+ let unsigned_tx_weight = anchor_psbt.unsigned_tx.weight().to_wu() - (anchor_psbt.unsigned_tx.input.len() as u64 * EMPTY_SCRIPT_SIG_WEIGHT);
- let signer = anchor_descriptor.derive_channel_signer(&self.signer_provider);
- let anchor_sig = signer.sign_holder_anchor_input(&anchor_tx, 0, &self.secp)?;
- anchor_tx.input[0].witness = anchor_descriptor.tx_input_witness(&anchor_sig);
+ let package_fee = total_input_amount -
+ anchor_psbt.unsigned_tx.output.iter().map(|output| output.value).sum();
+ let package_weight = unsigned_tx_weight + total_satisfaction_weight + commitment_tx.weight().to_wu();
+ if package_fee.to_sat() * 1000 / package_weight < package_target_feerate_sat_per_1000_weight.into() {
+ // On the first iteration of the loop, we may undershoot the target feerate because
+ // we had to add an OP_RETURN output in `process_coin_selection` which we didn't
+ // select sufficient coins for. Here we detect that case and go around again
+ // seeking additional weight.
+ if package_and_fixed_input_satisfaction_weight == starting_package_and_fixed_input_satisfaction_weight {
+ debug_assert!(anchor_psbt.unsigned_tx.output[0].script_pubkey.is_op_return(),
+ "Coin selection failed to select sufficient coins for its change output");
+ package_and_fixed_input_satisfaction_weight += anchor_psbt.unsigned_tx.output[0].weight().to_wu();
+ continue;
+ } else {
+ debug_assert!(false, "Coin selection failed to select sufficient coins");
+ }
+ }
- #[cfg(debug_assertions)] {
- let signed_tx_weight = anchor_tx.weight().to_wu();
- let expected_signed_tx_weight = unsigned_tx_weight + total_satisfaction_weight;
- // Our estimate should be within a 1% error margin of the actual weight and we should
- // never underestimate.
- assert!(expected_signed_tx_weight >= signed_tx_weight &&
- expected_signed_tx_weight - (expected_signed_tx_weight / 100) <= signed_tx_weight);
+ log_debug!(self.logger, "Signing anchor transaction {}", anchor_txid);
+ anchor_tx = self.utxo_source.sign_psbt(anchor_psbt)?;
+
+ let signer = anchor_descriptor.derive_channel_signer(&self.signer_provider);
+ let anchor_sig = signer.sign_holder_anchor_input(&anchor_tx, 0, &self.secp)?;
+ anchor_tx.input[0].witness = anchor_descriptor.tx_input_witness(&anchor_sig);
+
+ #[cfg(debug_assertions)] {
+ let signed_tx_weight = anchor_tx.weight().to_wu();
+ let expected_signed_tx_weight = unsigned_tx_weight + total_satisfaction_weight;
+ // Our estimate should be within a 1% error margin of the actual weight and we should
+ // never underestimate.
+ assert!(expected_signed_tx_weight >= signed_tx_weight &&
+ expected_signed_tx_weight - (expected_signed_tx_weight / 100) <= signed_tx_weight);
+
+ let expected_package_fee = Amount::from_sat(fee_for_weight(package_target_feerate_sat_per_1000_weight,
+ signed_tx_weight + commitment_tx.weight().to_wu()));
+ // Our fee should be within a 5% error margin of the expected fee based on the
+ // feerate and transaction weight and we should never pay less than required.
+ let fee_error_margin = expected_package_fee * 5 / 100;
+ assert!(package_fee >= expected_package_fee &&
+ package_fee - fee_error_margin <= expected_package_fee);
+ }
- let expected_package_fee = Amount::from_sat(fee_for_weight(package_target_feerate_sat_per_1000_weight,
- signed_tx_weight + commitment_tx.weight().to_wu()));
- let package_fee = total_input_amount -
- anchor_tx.output.iter().map(|output| output.value).sum();
- // Our fee should be within a 5% error margin of the expected fee based on the
- // feerate and transaction weight and we should never pay less than required.
- let fee_error_margin = expected_package_fee * 5 / 100;
- assert!(package_fee >= expected_package_fee &&
- package_fee - fee_error_margin <= expected_package_fee);
+ log_info!(self.logger, "Broadcasting anchor transaction {} to bump channel close with txid {}",
+ anchor_txid, commitment_tx.compute_txid());
+ self.broadcaster.broadcast_transactions(&[&commitment_tx, &anchor_tx]);
+ return Ok(());
}
-
- log_info!(self.logger, "Broadcasting anchor transaction {} to bump channel close with txid {}",
- anchor_txid, commitment_tx.compute_txid());
- self.broadcaster.broadcast_transactions(&[&commitment_tx, &anchor_tx]);
- Ok(())
}
/// Handles a [`BumpTransactionEvent::HTLCResolution`] event variant by producing a
projects / rust-lightning / commitdiff