//!
//! [`Event`]: crate::events::Event
-use core::convert::TryInto;
+use alloc::collections::BTreeMap;
use core::ops::Deref;
-use crate::chain::chaininterface::BroadcasterInterface;
+use crate::chain::chaininterface::{BroadcasterInterface, compute_feerate_sat_per_1000_weight, fee_for_weight, FEERATE_FLOOR_SATS_PER_KW};
use crate::chain::ClaimId;
use crate::io_extras::sink;
+use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI;
use crate::ln::chan_utils;
use crate::ln::chan_utils::{
ANCHOR_INPUT_WITNESS_WEIGHT, HTLC_SUCCESS_INPUT_ANCHOR_WITNESS_WEIGHT,
use crate::ln::features::ChannelTypeFeatures;
use crate::ln::PaymentPreimage;
use crate::prelude::*;
-use crate::sign::{ChannelSigner, EcdsaChannelSigner, SignerProvider};
+use crate::sign::{EcdsaChannelSigner, SignerProvider, WriteableEcdsaChannelSigner};
use crate::sync::Mutex;
use crate::util::logger::Logger;
const BASE_INPUT_WEIGHT: u64 = BASE_INPUT_SIZE * WITNESS_SCALE_FACTOR as u64;
-// TODO: Define typed abstraction over feerates to handle their conversions.
-fn compute_feerate_sat_per_1000_weight(fee_sat: u64, weight: u64) -> u32 {
- (fee_sat * 1000 / weight).try_into().unwrap_or(u32::max_value())
-}
-const fn fee_for_weight(feerate_sat_per_1000_weight: u32, weight: u64) -> u64 {
- ((feerate_sat_per_1000_weight as u64 * weight) + 1000 - 1) / 1000
+/// The parameters required to derive a channel signer via [`SignerProvider`].
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct ChannelDerivationParameters {
+ /// The value in satoshis of the channel we're attempting to spend the anchor output of.
+ pub value_satoshis: u64,
+ /// The unique identifier to re-derive the signer for the associated channel.
+ pub keys_id: [u8; 32],
+ /// The necessary channel parameters that need to be provided to the re-derived signer through
+ /// [`ChannelSigner::provide_channel_parameters`].
+ ///
+ /// [`ChannelSigner::provide_channel_parameters`]: crate::sign::ChannelSigner::provide_channel_parameters
+ pub transaction_parameters: ChannelTransactionParameters,
}
/// A descriptor used to sign for a commitment transaction's anchor output.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct AnchorDescriptor {
- /// A unique identifier used along with `channel_value_satoshis` to re-derive the
- /// [`InMemorySigner`] required to sign `input`.
- ///
- /// [`InMemorySigner`]: crate::sign::InMemorySigner
- pub channel_keys_id: [u8; 32],
- /// The value in satoshis of the channel we're attempting to spend the anchor output of. This is
- /// used along with `channel_keys_id` to re-derive the [`InMemorySigner`] required to sign
- /// `input`.
- ///
- /// [`InMemorySigner`]: crate::sign::InMemorySigner
- pub channel_value_satoshis: u64,
+ /// The parameters required to derive the signer for the anchor input.
+ pub channel_derivation_parameters: ChannelDerivationParameters,
/// The transaction input's outpoint corresponding to the commitment transaction's anchor
/// output.
pub outpoint: OutPoint,
}
+impl AnchorDescriptor {
+ /// Returns the UTXO to be spent by the anchor input, which can be obtained via
+ /// [`Self::unsigned_tx_input`].
+ pub fn previous_utxo(&self) -> TxOut {
+ TxOut {
+ script_pubkey: self.witness_script().to_v0_p2wsh(),
+ value: ANCHOR_OUTPUT_VALUE_SATOSHI,
+ }
+ }
+
+ /// Returns the unsigned transaction input spending the anchor output in the commitment
+ /// transaction.
+ pub fn unsigned_tx_input(&self) -> TxIn {
+ TxIn {
+ previous_output: self.outpoint.clone(),
+ script_sig: Script::new(),
+ sequence: Sequence::ENABLE_RBF_NO_LOCKTIME,
+ witness: Witness::new(),
+ }
+ }
+
+ /// Returns the witness script of the anchor output in the commitment transaction.
+ pub fn witness_script(&self) -> Script {
+ let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
+ chan_utils::get_anchor_redeemscript(&channel_params.broadcaster_pubkeys().funding_pubkey)
+ }
+
+ /// Returns the fully signed witness required to spend the anchor output in the commitment
+ /// transaction.
+ pub fn tx_input_witness(&self, signature: &Signature) -> Witness {
+ let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
+ chan_utils::build_anchor_input_witness(&channel_params.broadcaster_pubkeys().funding_pubkey, signature)
+ }
+
+ /// Derives the channel signer required to sign the anchor input.
+ pub fn derive_channel_signer<S: WriteableEcdsaChannelSigner, SP: Deref>(&self, signer_provider: &SP) -> S
+ where
+ SP::Target: SignerProvider<Signer = S>
+ {
+ let mut signer = signer_provider.derive_channel_signer(
+ self.channel_derivation_parameters.value_satoshis,
+ self.channel_derivation_parameters.keys_id,
+ );
+ signer.provide_channel_parameters(&self.channel_derivation_parameters.transaction_parameters);
+ signer
+ }
+}
+
/// A descriptor used to sign for a commitment transaction's HTLC output.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct HTLCDescriptor {
- /// A unique identifier used along with `channel_value_satoshis` to re-derive the
- /// [`InMemorySigner`] required to sign `input`.
- ///
- /// [`InMemorySigner`]: crate::sign::InMemorySigner
- pub channel_keys_id: [u8; 32],
- /// The value in satoshis of the channel we're attempting to spend the anchor output of. This is
- /// used along with `channel_keys_id` to re-derive the [`InMemorySigner`] required to sign
- /// `input`.
- ///
- /// [`InMemorySigner`]: crate::sign::InMemorySigner
- pub channel_value_satoshis: u64,
- /// The necessary channel parameters that need to be provided to the re-derived
- /// [`InMemorySigner`] through [`ChannelSigner::provide_channel_parameters`].
- ///
- /// [`InMemorySigner`]: crate::sign::InMemorySigner
- /// [`ChannelSigner::provide_channel_parameters`]: crate::sign::ChannelSigner::provide_channel_parameters
- pub channel_parameters: ChannelTransactionParameters,
+ /// The parameters required to derive the signer for the HTLC input.
+ pub channel_derivation_parameters: ChannelDerivationParameters,
/// The txid of the commitment transaction in which the HTLC output lives.
pub commitment_txid: Txid,
/// The number of the commitment transaction in which the HTLC output lives.
pub per_commitment_number: u64,
+ /// The key tweak corresponding to the number of the commitment transaction in which the HTLC
+ /// output lives. This tweak is applied to all the basepoints for both parties in the channel to
+ /// arrive at unique keys per commitment.
+ ///
+ /// See <https://github.com/lightning/bolts/blob/master/03-transactions.md#keys> for more info.
+ pub per_commitment_point: PublicKey,
/// The details of the HTLC as it appears in the commitment transaction.
pub htlc: HTLCOutputInCommitment,
/// The preimage, if `Some`, to claim the HTLC output with. If `None`, the timeout path must be
}
impl HTLCDescriptor {
+ /// Returns the outpoint of the HTLC output in the commitment transaction. This is the outpoint
+ /// being spent by the HTLC input in the HTLC transaction.
+ pub fn outpoint(&self) -> OutPoint {
+ OutPoint {
+ txid: self.commitment_txid,
+ vout: self.htlc.transaction_output_index.unwrap(),
+ }
+ }
+
+ /// Returns the UTXO to be spent by the HTLC input, which can be obtained via
+ /// [`Self::unsigned_tx_input`].
+ pub fn previous_utxo<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> TxOut {
+ TxOut {
+ script_pubkey: self.witness_script(secp).to_v0_p2wsh(),
+ value: self.htlc.amount_msat / 1000,
+ }
+ }
+
/// Returns the unsigned transaction input spending the HTLC output in the commitment
/// transaction.
pub fn unsigned_tx_input(&self) -> TxIn {
/// Returns the delayed output created as a result of spending the HTLC output in the commitment
/// transaction.
- pub fn tx_output<C: secp256k1::Signing + secp256k1::Verification>(
- &self, per_commitment_point: &PublicKey, secp: &Secp256k1<C>
- ) -> TxOut {
- let channel_params = self.channel_parameters.as_holder_broadcastable();
+ pub fn tx_output<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> TxOut {
+ let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
let broadcaster_keys = channel_params.broadcaster_pubkeys();
let counterparty_keys = channel_params.countersignatory_pubkeys();
let broadcaster_delayed_key = chan_utils::derive_public_key(
- secp, per_commitment_point, &broadcaster_keys.delayed_payment_basepoint
+ secp, &self.per_commitment_point, &broadcaster_keys.delayed_payment_basepoint
);
let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
- secp, per_commitment_point, &counterparty_keys.revocation_basepoint
+ secp, &self.per_commitment_point, &counterparty_keys.revocation_basepoint
);
chan_utils::build_htlc_output(
0 /* feerate_per_kw */, channel_params.contest_delay(), &self.htlc,
}
/// Returns the witness script of the HTLC output in the commitment transaction.
- pub fn witness_script<C: secp256k1::Signing + secp256k1::Verification>(
- &self, per_commitment_point: &PublicKey, secp: &Secp256k1<C>
- ) -> Script {
- let channel_params = self.channel_parameters.as_holder_broadcastable();
+ pub fn witness_script<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> Script {
+ let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
let broadcaster_keys = channel_params.broadcaster_pubkeys();
let counterparty_keys = channel_params.countersignatory_pubkeys();
let broadcaster_htlc_key = chan_utils::derive_public_key(
- secp, per_commitment_point, &broadcaster_keys.htlc_basepoint
+ secp, &self.per_commitment_point, &broadcaster_keys.htlc_basepoint
);
let counterparty_htlc_key = chan_utils::derive_public_key(
- secp, per_commitment_point, &counterparty_keys.htlc_basepoint
+ secp, &self.per_commitment_point, &counterparty_keys.htlc_basepoint
);
let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
- secp, per_commitment_point, &counterparty_keys.revocation_basepoint
+ secp, &self.per_commitment_point, &counterparty_keys.revocation_basepoint
);
chan_utils::get_htlc_redeemscript_with_explicit_keys(
&self.htlc, &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies(), &broadcaster_htlc_key, &counterparty_htlc_key,
signature, &self.counterparty_sig, &self.preimage, witness_script, &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies() /* opt_anchors */
)
}
+
+ /// Derives the channel signer required to sign the HTLC input.
+ pub fn derive_channel_signer<S: WriteableEcdsaChannelSigner, SP: Deref>(&self, signer_provider: &SP) -> S
+ where
+ SP::Target: SignerProvider<Signer = S>
+ {
+ let mut signer = signer_provider.derive_channel_signer(
+ self.channel_derivation_parameters.value_satoshis,
+ self.channel_derivation_parameters.keys_id,
+ );
+ signer.provide_channel_parameters(&self.channel_derivation_parameters.transaction_parameters);
+ signer
+ }
}
/// Represents the different types of transactions, originating from LDK, to be bumped.
/// broadcast first, as the child anchor transaction depends on it.
///
/// The consumer should be able to sign for any of the additional inputs included within the
- /// child anchor transaction. To sign its anchor input, an [`InMemorySigner`] should be
- /// re-derived through [`KeysManager::derive_channel_keys`] with the help of
- /// [`AnchorDescriptor::channel_keys_id`] and [`AnchorDescriptor::channel_value_satoshis`]. The
- /// anchor input signature can be computed with [`EcdsaChannelSigner::sign_holder_anchor_input`],
- /// which can then be provided to [`build_anchor_input_witness`] along with the `funding_pubkey`
- /// to obtain the full witness required to spend.
+ /// child anchor transaction. To sign its anchor input, an [`EcdsaChannelSigner`] should be
+ /// re-derived through [`AnchorDescriptor::derive_channel_signer`]. The anchor input signature
+ /// can be computed with [`EcdsaChannelSigner::sign_holder_anchor_input`], which can then be
+ /// provided to [`build_anchor_input_witness`] along with the `funding_pubkey` to obtain the
+ /// full witness required to spend.
///
/// It is possible to receive more than one instance of this event if a valid child anchor
/// transaction is never broadcast or is but not with a sufficient fee to be mined. Care should
/// an empty `pending_htlcs`), confirmation of the commitment transaction can be considered to
/// be not urgent.
///
- /// [`InMemorySigner`]: crate::sign::InMemorySigner
- /// [`KeysManager::derive_channel_keys`]: crate::sign::KeysManager::derive_channel_keys
+ /// [`EcdsaChannelSigner`]: crate::sign::EcdsaChannelSigner
/// [`EcdsaChannelSigner::sign_holder_anchor_input`]: crate::sign::EcdsaChannelSigner::sign_holder_anchor_input
/// [`build_anchor_input_witness`]: crate::ln::chan_utils::build_anchor_input_witness
ChannelClose {
/// broadcast by the consumer of the event.
///
/// The consumer should be able to sign for any of the non-HTLC inputs added to the resulting
- /// HTLC transaction. To sign HTLC inputs, an [`InMemorySigner`] should be re-derived through
- /// [`KeysManager::derive_channel_keys`] with the help of `channel_keys_id` and
- /// `channel_value_satoshis`. Each HTLC input's signature can be computed with
- /// [`EcdsaChannelSigner::sign_holder_htlc_transaction`], which can then be provided to
- /// [`HTLCDescriptor::tx_input_witness`] to obtain the fully signed witness required to spend.
+ /// HTLC transaction. To sign HTLC inputs, an [`EcdsaChannelSigner`] should be re-derived
+ /// through [`HTLCDescriptor::derive_channel_signer`]. Each HTLC input's signature can be
+ /// computed with [`EcdsaChannelSigner::sign_holder_htlc_transaction`], which can then be
+ /// provided to [`HTLCDescriptor::tx_input_witness`] to obtain the fully signed witness required
+ /// to spend.
///
/// It is possible to receive more than one instance of this event if a valid HTLC transaction
/// is never broadcast or is but not with a sufficient fee to be mined. Care should be taken by
/// longer able to commit external confirmed funds to the HTLC transaction or the fee committed
/// to the HTLC transaction is greater in value than the HTLCs being claimed.
///
- /// [`InMemorySigner`]: crate::sign::InMemorySigner
- /// [`KeysManager::derive_channel_keys`]: crate::sign::KeysManager::derive_channel_keys
+ /// [`EcdsaChannelSigner`]: crate::sign::EcdsaChannelSigner
/// [`EcdsaChannelSigner::sign_holder_htlc_transaction`]: crate::sign::EcdsaChannelSigner::sign_holder_htlc_transaction
/// [`HTLCDescriptor::tx_input_witness`]: HTLCDescriptor::tx_input_witness
HTLCResolution {
/// An input that must be included in a transaction when performing coin selection through
/// [`CoinSelectionSource::select_confirmed_utxos`]. It is guaranteed to be a SegWit input, so it
/// must have an empty [`TxIn::script_sig`] when spent.
+#[derive(Clone, Debug, Hash, PartialOrd, Ord, PartialEq, Eq)]
pub struct Input {
/// The unique identifier of the input.
pub outpoint: OutPoint,
+ /// The UTXO being spent by the input.
+ pub previous_utxo: TxOut,
/// The upper-bound weight consumed by the input's full [`TxIn::script_sig`] and
/// [`TxIn::witness`], each with their lengths included, required to satisfy the output's
/// script.
/// An unspent transaction output that is available to spend resulting from a successful
/// [`CoinSelection`] attempt.
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Hash, PartialOrd, Ord, PartialEq, Eq)]
pub struct Utxo {
/// The unique identifier of the output.
pub outpoint: OutPoint,
/// The result of a successful coin selection attempt for a transaction requiring additional UTXOs
/// to cover its fees.
+#[derive(Clone, Debug)]
pub struct CoinSelection {
/// The set of UTXOs (with at least 1 confirmation) to spend and use within a transaction
/// requiring additional fees.
- confirmed_utxos: Vec<Utxo>,
+ pub confirmed_utxos: Vec<Utxo>,
/// An additional output tracking whether any change remained after coin selection. This output
/// should always have a value above dust for its given `script_pubkey`. It should not be
/// spent until the transaction it belongs to confirms to ensure mempool descendant limits are
/// not met. This implies no other party should be able to spend it except us.
- change_output: Option<TxOut>,
+ pub change_output: Option<TxOut>,
}
/// An abstraction over a bitcoin wallet that can perform coin selection over a set of UTXOs and can
/// which UTXOs to double spend is left to the implementation, but it must strive to keep the
/// set of other claims being double spent to a minimum.
fn select_confirmed_utxos(
- &self, claim_id: ClaimId, must_spend: &[Input], must_pay_to: &[TxOut],
+ &self, claim_id: ClaimId, must_spend: Vec<Input>, must_pay_to: &[TxOut],
target_feerate_sat_per_1000_weight: u32,
) -> Result<CoinSelection, ()>;
/// Signs and provides the full witness for all inputs within the transaction known to the
/// trait (i.e., any provided via [`CoinSelectionSource::select_confirmed_utxos`]).
- fn sign_tx(&self, tx: &mut Transaction) -> Result<(), ()>;
+ fn sign_tx(&self, tx: Transaction) -> Result<Transaction, ()>;
}
/// An alternative to [`CoinSelectionSource`] that can be implemented and used along [`Wallet`] to
/// Signs and provides the full [`TxIn::script_sig`] and [`TxIn::witness`] for all inputs within
/// the transaction known to the wallet (i.e., any provided via
/// [`WalletSource::list_confirmed_utxos`]).
- fn sign_tx(&self, tx: &mut Transaction) -> Result<(), ()>;
+ fn sign_tx(&self, tx: Transaction) -> Result<Transaction, ()>;
}
/// A wrapper over [`WalletSource`] that implements [`CoinSelection`] by preferring UTXOs that would
/// avoid conflicting double spends. If not enough UTXOs are available to do so, conflicting double
/// spends may happen.
-pub struct Wallet<W: Deref> where W::Target: WalletSource {
+pub struct Wallet<W: Deref, L: Deref>
+where
+ W::Target: WalletSource,
+ L::Target: Logger
+{
source: W,
+ logger: L,
// TODO: Do we care about cleaning this up once the UTXOs have a confirmed spend? We can do so
// by checking whether any UTXOs that exist in the map are no longer returned in
// `list_confirmed_utxos`.
locked_utxos: Mutex<HashMap<OutPoint, ClaimId>>,
}
-impl<W: Deref> Wallet<W> where W::Target: WalletSource {
+impl<W: Deref, L: Deref> Wallet<W, L>
+where
+ W::Target: WalletSource,
+ L::Target: Logger
+{
/// Returns a new instance backed by the given [`WalletSource`] that serves as an implementation
/// of [`CoinSelectionSource`].
- pub fn new(source: W) -> Self {
- Self { source, locked_utxos: Mutex::new(HashMap::new()) }
+ pub fn new(source: W, logger: L) -> Self {
+ Self { source, logger, locked_utxos: Mutex::new(HashMap::new()) }
}
/// Performs coin selection on the set of UTXOs obtained from
let mut eligible_utxos = utxos.iter().filter_map(|utxo| {
if let Some(utxo_claim_id) = locked_utxos.get(&utxo.outpoint) {
if *utxo_claim_id != claim_id && !force_conflicting_utxo_spend {
+ log_trace!(self.logger, "Skipping UTXO {} to prevent conflicting spend", utxo.outpoint);
return None;
}
}
if should_spend {
Some((utxo, fee_to_spend_utxo))
} else {
+ log_trace!(self.logger, "Skipping UTXO {} due to dust proximity after spend", utxo.outpoint);
None
}
}).collect::<Vec<_>>();
selected_utxos.push(utxo.clone());
}
if selected_amount < target_amount_sat + total_fees {
+ log_debug!(self.logger, "Insufficient funds to meet target feerate {} sat/kW",
+ target_feerate_sat_per_1000_weight);
return Err(());
}
for utxo in &selected_utxos {
);
let change_output_amount = remaining_amount.saturating_sub(change_output_fee);
let change_output = if change_output_amount < change_script.dust_value().to_sat() {
+ log_debug!(self.logger, "Coin selection attempt did not yield change output");
None
} else {
Some(TxOut { script_pubkey: change_script, value: change_output_amount })
}
}
-impl<W: Deref> CoinSelectionSource for Wallet<W> where W::Target: WalletSource {
+impl<W: Deref, L: Deref> CoinSelectionSource for Wallet<W, L>
+where
+ W::Target: WalletSource,
+ L::Target: Logger
+{
fn select_confirmed_utxos(
- &self, claim_id: ClaimId, must_spend: &[Input], must_pay_to: &[TxOut],
+ &self, claim_id: ClaimId, must_spend: Vec<Input>, must_pay_to: &[TxOut],
target_feerate_sat_per_1000_weight: u32,
) -> Result<CoinSelection, ()> {
let utxos = self.source.list_confirmed_utxos()?;
((BASE_TX_SIZE + total_output_size) * WITNESS_SCALE_FACTOR as u64);
let target_amount_sat = must_pay_to.iter().map(|output| output.value).sum();
let do_coin_selection = |force_conflicting_utxo_spend: bool, tolerate_high_network_feerates: bool| {
+ log_debug!(self.logger, "Attempting coin selection targeting {} sat/kW (force_conflicting_utxo_spend = {}, tolerate_high_network_feerates = {})",
+ target_feerate_sat_per_1000_weight, force_conflicting_utxo_spend, tolerate_high_network_feerates);
self.select_confirmed_utxos_internal(
&utxos, claim_id, force_conflicting_utxo_spend, tolerate_high_network_feerates,
target_feerate_sat_per_1000_weight, preexisting_tx_weight, target_amount_sat,
.or_else(|_| do_coin_selection(true, true))
}
- fn sign_tx(&self, tx: &mut Transaction) -> Result<(), ()> {
+ fn sign_tx(&self, tx: Transaction) -> Result<Transaction, ()> {
self.source.sign_tx(tx)
}
}
// match, but we still need to have at least one output in the transaction for it to be
// considered standard. We choose to go with an empty OP_RETURN as it is the cheapest
// way to include a dummy output.
+ log_debug!(self.logger, "Including dummy OP_RETURN output since an output is needed and a change output was not provided");
tx.output.push(TxOut {
value: 0,
script_pubkey: Script::new_op_return(&[]),
}
}
- /// Returns an unsigned transaction spending an anchor output of the commitment transaction, and
- /// any additional UTXOs sourced, to bump the commitment transaction's fee.
- fn build_anchor_tx(
- &self, claim_id: ClaimId, target_feerate_sat_per_1000_weight: u32,
- commitment_tx: &Transaction, anchor_descriptor: &AnchorDescriptor,
- ) -> Result<Transaction, ()> {
+ /// Handles a [`BumpTransactionEvent::ChannelClose`] event variant by producing a fully-signed
+ /// transaction spending an anchor output of the commitment transaction to bump its fee and
+ /// broadcasts them to the network as a package.
+ fn handle_channel_close(
+ &self, claim_id: ClaimId, package_target_feerate_sat_per_1000_weight: u32,
+ commitment_tx: &Transaction, commitment_tx_fee_sat: u64, anchor_descriptor: &AnchorDescriptor,
+ ) -> Result<(), ()> {
+ // Our commitment transaction already has fees allocated to it, so we should take them into
+ // account. We compute its feerate and subtract it from the package target, using the result
+ // as the target feerate for our anchor transaction. Unfortunately, this results in users
+ // overpaying by a small margin since we don't yet know the anchor transaction size, and
+ // avoiding the small overpayment only makes our API even more complex.
+ let commitment_tx_sat_per_1000_weight: u32 = compute_feerate_sat_per_1000_weight(
+ commitment_tx_fee_sat, commitment_tx.weight() as u64,
+ );
+ let anchor_target_feerate_sat_per_1000_weight = core::cmp::max(
+ package_target_feerate_sat_per_1000_weight - commitment_tx_sat_per_1000_weight,
+ FEERATE_FLOOR_SATS_PER_KW,
+ );
+
+ log_debug!(self.logger, "Peforming coin selection for anchor transaction targeting {} sat/kW",
+ anchor_target_feerate_sat_per_1000_weight);
let must_spend = vec![Input {
outpoint: anchor_descriptor.outpoint,
+ previous_utxo: anchor_descriptor.previous_utxo(),
satisfaction_weight: commitment_tx.weight() as u64 + ANCHOR_INPUT_WITNESS_WEIGHT + EMPTY_SCRIPT_SIG_WEIGHT,
}];
let coin_selection = self.utxo_source.select_confirmed_utxos(
- claim_id, &must_spend, &[], target_feerate_sat_per_1000_weight,
+ claim_id, must_spend, &[], anchor_target_feerate_sat_per_1000_weight,
)?;
- let mut tx = Transaction {
+ let mut anchor_tx = Transaction {
version: 2,
lock_time: PackedLockTime::ZERO, // TODO: Use next best height.
- input: vec![TxIn {
- previous_output: anchor_descriptor.outpoint,
- script_sig: Script::new(),
- sequence: Sequence::ZERO,
- witness: Witness::new(),
- }],
+ input: vec![anchor_descriptor.unsigned_tx_input()],
output: vec![],
};
- self.process_coin_selection(&mut tx, coin_selection);
- Ok(tx)
- }
+ #[cfg(debug_assertions)]
+ let total_satisfaction_weight =
+ coin_selection.confirmed_utxos.iter().map(|utxo| utxo.satisfaction_weight).sum::<u64>() +
+ ANCHOR_INPUT_WITNESS_WEIGHT + EMPTY_SCRIPT_SIG_WEIGHT;
- /// Handles a [`BumpTransactionEvent::ChannelClose`] event variant by producing a fully-signed
- /// transaction spending an anchor output of the commitment transaction to bump its fee and
- /// broadcasts them to the network as a package.
- fn handle_channel_close(
- &self, claim_id: ClaimId, package_target_feerate_sat_per_1000_weight: u32,
- commitment_tx: &Transaction, commitment_tx_fee_sat: u64, anchor_descriptor: &AnchorDescriptor,
- ) -> Result<(), ()> {
- // Compute the feerate the anchor transaction must meet to meet the overall feerate for the
- // package (commitment + anchor transactions).
- let commitment_tx_sat_per_1000_weight: u32 = compute_feerate_sat_per_1000_weight(
- commitment_tx_fee_sat, commitment_tx.weight() as u64,
- );
- if commitment_tx_sat_per_1000_weight >= package_target_feerate_sat_per_1000_weight {
- // If the commitment transaction already has a feerate high enough on its own, broadcast
- // it as is without a child.
- self.broadcaster.broadcast_transactions(&[&commitment_tx]);
- return Ok(());
- }
+ self.process_coin_selection(&mut anchor_tx, coin_selection);
+ let anchor_txid = anchor_tx.txid();
- let mut anchor_tx = self.build_anchor_tx(
- claim_id, package_target_feerate_sat_per_1000_weight, commitment_tx, anchor_descriptor,
- )?;
debug_assert_eq!(anchor_tx.output.len(), 1);
+ #[cfg(debug_assertions)]
+ let unsigned_tx_weight = anchor_tx.weight() as u64 - (anchor_tx.input.len() as u64 * EMPTY_SCRIPT_SIG_WEIGHT);
- self.utxo_source.sign_tx(&mut anchor_tx)?;
- let signer = self.signer_provider.derive_channel_signer(
- anchor_descriptor.channel_value_satoshis, anchor_descriptor.channel_keys_id,
- );
+ log_debug!(self.logger, "Signing anchor transaction {}", anchor_txid);
+ anchor_tx = self.utxo_source.sign_tx(anchor_tx)?;
+
+ 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 =
- chan_utils::build_anchor_input_witness(&signer.pubkeys().funding_pubkey, &anchor_sig);
+ anchor_tx.input[0].witness = anchor_descriptor.tx_input_witness(&anchor_sig);
+
+ #[cfg(debug_assertions)] {
+ let signed_tx_weight = anchor_tx.weight() as u64;
+ 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_info!(self.logger, "Broadcasting anchor transaction {} to bump channel close with txid {}",
+ anchor_txid, commitment_tx.txid());
self.broadcaster.broadcast_transactions(&[&commitment_tx, &anchor_tx]);
Ok(())
}
- /// Returns an unsigned, fee-bumped HTLC transaction, along with the set of signers required to
- /// fulfill the witness for each HTLC input within it.
- fn build_htlc_tx(
+ /// Handles a [`BumpTransactionEvent::HTLCResolution`] event variant by producing a
+ /// fully-signed, fee-bumped HTLC transaction that is broadcast to the network.
+ fn handle_htlc_resolution(
&self, claim_id: ClaimId, target_feerate_sat_per_1000_weight: u32,
htlc_descriptors: &[HTLCDescriptor], tx_lock_time: PackedLockTime,
- ) -> Result<(Transaction, HashMap<[u8; 32], <SP::Target as SignerProvider>::Signer>), ()> {
- let mut tx = Transaction {
+ ) -> Result<(), ()> {
+ let mut htlc_tx = Transaction {
version: 2,
lock_time: tx_lock_time,
input: vec![],
output: vec![],
};
- // Unfortunately, we need to derive the signer for each HTLC ahead of time to obtain its
- // input.
- let mut signers = HashMap::new();
let mut must_spend = Vec::with_capacity(htlc_descriptors.len());
for htlc_descriptor in htlc_descriptors {
- let signer = signers.entry(htlc_descriptor.channel_keys_id)
- .or_insert_with(||
- self.signer_provider.derive_channel_signer(
- htlc_descriptor.channel_value_satoshis, htlc_descriptor.channel_keys_id,
- )
- );
- let per_commitment_point = signer.get_per_commitment_point(
- htlc_descriptor.per_commitment_number, &self.secp
- );
-
let htlc_input = htlc_descriptor.unsigned_tx_input();
must_spend.push(Input {
outpoint: htlc_input.previous_output.clone(),
+ previous_utxo: htlc_descriptor.previous_utxo(&self.secp),
satisfaction_weight: EMPTY_SCRIPT_SIG_WEIGHT + if htlc_descriptor.preimage.is_some() {
HTLC_SUCCESS_INPUT_ANCHOR_WITNESS_WEIGHT
} else {
HTLC_TIMEOUT_INPUT_ANCHOR_WITNESS_WEIGHT
},
});
- tx.input.push(htlc_input);
- let htlc_output = htlc_descriptor.tx_output(&per_commitment_point, &self.secp);
- tx.output.push(htlc_output);
+ htlc_tx.input.push(htlc_input);
+ let htlc_output = htlc_descriptor.tx_output(&self.secp);
+ htlc_tx.output.push(htlc_output);
}
+ log_debug!(self.logger, "Peforming coin selection for HTLC transaction targeting {} sat/kW",
+ target_feerate_sat_per_1000_weight);
+ #[cfg(debug_assertions)]
+ let must_spend_satisfaction_weight =
+ must_spend.iter().map(|input| input.satisfaction_weight).sum::<u64>();
let coin_selection = self.utxo_source.select_confirmed_utxos(
- claim_id, &must_spend, &tx.output, target_feerate_sat_per_1000_weight,
+ claim_id, must_spend, &htlc_tx.output, target_feerate_sat_per_1000_weight,
)?;
- self.process_coin_selection(&mut tx, coin_selection);
- Ok((tx, signers))
- }
+ #[cfg(debug_assertions)]
+ let total_satisfaction_weight =
+ coin_selection.confirmed_utxos.iter().map(|utxo| utxo.satisfaction_weight).sum::<u64>() +
+ must_spend_satisfaction_weight;
+ self.process_coin_selection(&mut htlc_tx, coin_selection);
- /// Handles a [`BumpTransactionEvent::HTLCResolution`] event variant by producing a
- /// fully-signed, fee-bumped HTLC transaction that is broadcast to the network.
- fn handle_htlc_resolution(
- &self, claim_id: ClaimId, target_feerate_sat_per_1000_weight: u32,
- htlc_descriptors: &[HTLCDescriptor], tx_lock_time: PackedLockTime,
- ) -> Result<(), ()> {
- let (mut htlc_tx, signers) = self.build_htlc_tx(
- claim_id, target_feerate_sat_per_1000_weight, htlc_descriptors, tx_lock_time,
- )?;
+ #[cfg(debug_assertions)]
+ let unsigned_tx_weight = htlc_tx.weight() as u64 - (htlc_tx.input.len() as u64 * EMPTY_SCRIPT_SIG_WEIGHT);
+
+ log_debug!(self.logger, "Signing HTLC transaction {}", htlc_tx.txid());
+ htlc_tx = self.utxo_source.sign_tx(htlc_tx)?;
- self.utxo_source.sign_tx(&mut htlc_tx)?;
+ let mut signers = BTreeMap::new();
for (idx, htlc_descriptor) in htlc_descriptors.iter().enumerate() {
- let signer = signers.get(&htlc_descriptor.channel_keys_id).unwrap();
- let htlc_sig = signer.sign_holder_htlc_transaction(
- &htlc_tx, idx, htlc_descriptor, &self.secp
- )?;
- let per_commitment_point = signer.get_per_commitment_point(
- htlc_descriptor.per_commitment_number, &self.secp
- );
- let witness_script = htlc_descriptor.witness_script(&per_commitment_point, &self.secp);
+ let signer = signers.entry(htlc_descriptor.channel_derivation_parameters.keys_id)
+ .or_insert_with(|| htlc_descriptor.derive_channel_signer(&self.signer_provider));
+ let htlc_sig = signer.sign_holder_htlc_transaction(&htlc_tx, idx, htlc_descriptor, &self.secp)?;
+ let witness_script = htlc_descriptor.witness_script(&self.secp);
htlc_tx.input[idx].witness = htlc_descriptor.tx_input_witness(&htlc_sig, &witness_script);
}
+ #[cfg(debug_assertions)] {
+ let signed_tx_weight = htlc_tx.weight() as u64;
+ 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_info!(self.logger, "Broadcasting {}", log_tx!(htlc_tx));
self.broadcaster.broadcast_transactions(&[&htlc_tx]);
Ok(())
}
match event {
BumpTransactionEvent::ChannelClose {
claim_id, package_target_feerate_sat_per_1000_weight, commitment_tx,
- anchor_descriptor, commitment_tx_fee_satoshis, ..
+ commitment_tx_fee_satoshis, anchor_descriptor, ..
} => {
+ log_info!(self.logger, "Handling channel close bump (claim_id = {}, commitment_txid = {})",
+ log_bytes!(claim_id.0), commitment_tx.txid());
if let Err(_) = self.handle_channel_close(
*claim_id, *package_target_feerate_sat_per_1000_weight, commitment_tx,
*commitment_tx_fee_satoshis, anchor_descriptor,
BumpTransactionEvent::HTLCResolution {
claim_id, target_feerate_sat_per_1000_weight, htlc_descriptors, tx_lock_time,
} => {
+ log_info!(self.logger, "Handling HTLC bump (claim_id = {}, htlcs_to_claim = {})",
+ log_bytes!(claim_id.0), log_iter!(htlc_descriptors.iter().map(|d| d.outpoint())));
if let Err(_) = self.handle_htlc_resolution(
*claim_id, *target_feerate_sat_per_1000_weight, htlc_descriptors, *tx_lock_time,
) {
projects / rust-lightning / blobdiff