Add min feerate checks

lightning/src/chain/chaininterface.rs

@@ -13,6 +13,8 @@
 //! Includes traits for monitoring and receiving notifications of new blocks and block
 //! disconnections, transaction broadcasting, and feerate information requests.
 
+use core::{cmp, ops::Deref};
+
 use bitcoin::blockdata::transaction::Transaction;
 
 /// An interface to send a transaction to the Bitcoin network.
@@ -41,14 +43,79 @@ pub enum ConfirmationTarget {
 pub trait FeeEstimator {
 	/// Gets estimated satoshis of fee required per 1000 Weight-Units.
 	///
-	/// Must return a value no smaller than 253 (ie 1 satoshi-per-byte rounded up to ensure later
-	/// round-downs don't put us below 1 satoshi-per-byte).
+	/// LDK will wrap this method and ensure that the value returned is no smaller than 253
+	/// (ie 1 satoshi-per-byte rounded up to ensure later round-downs don't put us below 1 satoshi-per-byte).
 	///
-	/// This method can be implemented with the following unit conversions:
-	///  * max(satoshis-per-byte * 250, 253)
-	///  * max(satoshis-per-kbyte / 4, 253)
+	/// The following unit conversions can be used to convert to sats/KW:
+	///  * satoshis-per-byte * 250
+	///  * satoshis-per-kbyte / 4
 	fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u32;
 }
 
+// We need `FeeEstimator` implemented so that in some places where we only have a shared
+// reference to a `Deref` to a `FeeEstimator`, we can still wrap it.
+impl<D: Deref> FeeEstimator for D where D::Target: FeeEstimator {
+	fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u32 {
+		(**self).get_est_sat_per_1000_weight(confirmation_target)
+	}
+}
+
 /// Minimum relay fee as required by bitcoin network mempool policy.
 pub const MIN_RELAY_FEE_SAT_PER_1000_WEIGHT: u64 = 4000;
+/// Minimum feerate that takes a sane approach to bitcoind weight-to-vbytes rounding.
+/// See the following Core Lightning commit for an explanation:
+/// https://github.com/ElementsProject/lightning/commit/2e687b9b352c9092b5e8bd4a688916ac50b44af0
+pub const FEERATE_FLOOR_SATS_PER_KW: u32 = 253;
+
+/// Wraps a `Deref` to a `FeeEstimator` so that any fee estimations provided by it
+/// are bounded below by `FEERATE_FLOOR_SATS_PER_KW` (253 sats/KW)
+pub(crate) struct LowerBoundedFeeEstimator<F: Deref>(pub F) where F::Target: FeeEstimator;
+
+impl<F: Deref> LowerBoundedFeeEstimator<F> where F::Target: FeeEstimator {
+	/// Creates a new `LowerBoundedFeeEstimator` which wraps the provided fee_estimator
+	pub fn new(fee_estimator: F) -> Self {
+		LowerBoundedFeeEstimator(fee_estimator)
+	}
+}
+
+impl<F: Deref> FeeEstimator for LowerBoundedFeeEstimator<F> where F::Target: FeeEstimator {
+	fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u32 {
+		cmp::max(
+			self.0.get_est_sat_per_1000_weight(confirmation_target),
+			FEERATE_FLOOR_SATS_PER_KW,
+		)
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::{FEERATE_FLOOR_SATS_PER_KW, LowerBoundedFeeEstimator, ConfirmationTarget, FeeEstimator};
+
+	struct TestFeeEstimator {
+		sat_per_kw: u32,
+	}
+
+	impl FeeEstimator for TestFeeEstimator {
+		fn get_est_sat_per_1000_weight(&self, _: ConfirmationTarget) -> u32 {
+			self.sat_per_kw
+		}
+	}
+
+	#[test]
+	fn test_fee_estimator_less_than_floor() {
+		let sat_per_kw = FEERATE_FLOOR_SATS_PER_KW - 1;
+		let test_fee_estimator = &TestFeeEstimator { sat_per_kw };
+		let fee_estimator = LowerBoundedFeeEstimator::new(test_fee_estimator);
+
+		assert_eq!(fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background), FEERATE_FLOOR_SATS_PER_KW);
+	}
+
+	#[test]
+	fn test_fee_estimator_greater_than_floor() {
+		let sat_per_kw = FEERATE_FLOOR_SATS_PER_KW + 1;
+		let test_fee_estimator = &TestFeeEstimator { sat_per_kw };
+		let fee_estimator = LowerBoundedFeeEstimator::new(test_fee_estimator);
+
+		assert_eq!(fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background), sat_per_kw);
+	}
+}

lightning/src/chain/channelmonitor.rs

@@ -40,7 +40,7 @@ use ln::chan_utils::{CounterpartyCommitmentSecrets, HTLCOutputInCommitment, HTLC
 use ln::channelmanager::HTLCSource;
 use chain;
 use chain::{BestBlock, WatchedOutput};
-use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
+use chain::chaininterface::{BroadcasterInterface, FeeEstimator, LowerBoundedFeeEstimator};
 use chain::transaction::{OutPoint, TransactionData};
 use chain::keysinterface::{SpendableOutputDescriptor, StaticPaymentOutputDescriptor, DelayedPaymentOutputDescriptor, Sign, KeysInterface};
 use chain::onchaintx::OnchainTxHandler;
@@ -1104,7 +1104,7 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 		payment_hash: &PaymentHash,
 		payment_preimage: &PaymentPreimage,
 		broadcaster: &B,
-		fee_estimator: &F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: &L,
 	) where
 		B::Target: BroadcasterInterface,
@@ -1300,8 +1300,9 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 		F::Target: FeeEstimator,
 		L::Target: Logger,
 	{
+		let bounded_fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
 		self.inner.lock().unwrap().transactions_confirmed(
-			header, txdata, height, broadcaster, fee_estimator, logger)
+			header, txdata, height, broadcaster, &bounded_fee_estimator, logger)
 	}
 
 	/// Processes a transaction that was reorganized out of the chain.
@@ -1321,8 +1322,9 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 		F::Target: FeeEstimator,
 		L::Target: Logger,
 	{
+		let bounded_fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
 		self.inner.lock().unwrap().transaction_unconfirmed(
-			txid, broadcaster, fee_estimator, logger);
+			txid, broadcaster, &bounded_fee_estimator, logger);
 	}
 
 	/// Updates the monitor with the current best chain tip, returning new outputs to watch. See
@@ -1345,8 +1347,9 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 		F::Target: FeeEstimator,
 		L::Target: Logger,
 	{
+		let bounded_fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
 		self.inner.lock().unwrap().best_block_updated(
-			header, height, broadcaster, fee_estimator, logger)
+			header, height, broadcaster, &bounded_fee_estimator, logger)
 	}
 
 	/// Returns the set of txids that should be monitored for re-organization out of the chain.
@@ -1882,7 +1885,9 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 
 	/// Provides a payment_hash->payment_preimage mapping. Will be automatically pruned when all
 	/// commitment_tx_infos which contain the payment hash have been revoked.
-	fn provide_payment_preimage<B: Deref, F: Deref, L: Deref>(&mut self, payment_hash: &PaymentHash, payment_preimage: &PaymentPreimage, broadcaster: &B, fee_estimator: &F, logger: &L)
+	fn provide_payment_preimage<B: Deref, F: Deref, L: Deref>(
+		&mut self, payment_hash: &PaymentHash, payment_preimage: &PaymentPreimage, broadcaster: &B,
+		fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L)
 	where B::Target: BroadcasterInterface,
 		    F::Target: FeeEstimator,
 		    L::Target: Logger,
@@ -1980,7 +1985,8 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 				},
 				ChannelMonitorUpdateStep::PaymentPreimage { payment_preimage } => {
 					log_trace!(logger, "Updating ChannelMonitor with payment preimage");
-					self.provide_payment_preimage(&PaymentHash(Sha256::hash(&payment_preimage.0[..]).into_inner()), &payment_preimage, broadcaster, fee_estimator, logger)
+					let bounded_fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
+					self.provide_payment_preimage(&PaymentHash(Sha256::hash(&payment_preimage.0[..]).into_inner()), &payment_preimage, broadcaster, &bounded_fee_estimator, logger)
 				},
 				ChannelMonitorUpdateStep::CommitmentSecret { idx, secret } => {
 					log_trace!(logger, "Updating ChannelMonitor with commitment secret");
@@ -2406,15 +2412,16 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		let block_hash = header.block_hash();
 		self.best_block = BestBlock::new(block_hash, height);
 
-		self.transactions_confirmed(header, txdata, height, broadcaster, fee_estimator, logger)
+		let bounded_fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
+		self.transactions_confirmed(header, txdata, height, broadcaster, &bounded_fee_estimator, logger)
 	}
 
 	fn best_block_updated<B: Deref, F: Deref, L: Deref>(
 		&mut self,
 		header: &BlockHeader,
 		height: u32,
 		broadcaster: B,
-		fee_estimator: F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: L,
 	) -> Vec<TransactionOutputs>
 	where
@@ -2441,7 +2448,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		txdata: &TransactionData,
 		height: u32,
 		broadcaster: B,
-		fee_estimator: F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: L,
 	) -> Vec<TransactionOutputs>
 	where
@@ -2538,7 +2545,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		mut watch_outputs: Vec<TransactionOutputs>,
 		mut claimable_outpoints: Vec<PackageTemplate>,
 		broadcaster: &B,
-		fee_estimator: &F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: &L,
 	) -> Vec<TransactionOutputs>
 	where
@@ -2676,7 +2683,8 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		//- maturing spendable output has transaction paying us has been disconnected
 		self.onchain_events_awaiting_threshold_conf.retain(|ref entry| entry.height < height);
 
-		self.onchain_tx_handler.block_disconnected(height, broadcaster, fee_estimator, logger);
+		let bounded_fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
+		self.onchain_tx_handler.block_disconnected(height, broadcaster, &bounded_fee_estimator, logger);
 
 		self.best_block = BestBlock::new(header.prev_blockhash, height - 1);
 	}
@@ -2685,7 +2693,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		&mut self,
 		txid: &Txid,
 		broadcaster: B,
-		fee_estimator: F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: L,
 	) where
 		B::Target: BroadcasterInterface,
@@ -3428,6 +3436,8 @@ mod tests {
 
 	use hex;
 
+	use crate::chain::chaininterface::LowerBoundedFeeEstimator;
+
 	use super::ChannelMonitorUpdateStep;
 	use ::{check_added_monitors, check_closed_broadcast, check_closed_event, check_spends, get_local_commitment_txn, get_monitor, get_route_and_payment_hash, unwrap_send_err};
 	use chain::{BestBlock, Confirm};
@@ -3549,7 +3559,7 @@ mod tests {
 		let secp_ctx = Secp256k1::new();
 		let logger = Arc::new(TestLogger::new());
 		let broadcaster = Arc::new(TestBroadcaster{txn_broadcasted: Mutex::new(Vec::new()), blocks: Arc::new(Mutex::new(Vec::new()))});
-		let fee_estimator = Arc::new(TestFeeEstimator { sat_per_kw: Mutex::new(253) });
+		let fee_estimator = TestFeeEstimator { sat_per_kw: Mutex::new(253) };
 
 		let dummy_key = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
 		let dummy_tx = Transaction { version: 0, lock_time: 0, input: Vec::new(), output: Vec::new() };
@@ -3648,7 +3658,8 @@ mod tests {
 		monitor.provide_latest_counterparty_commitment_tx(dummy_txid, preimages_slice_to_htlc_outputs!(preimages[17..20]), 281474976710653, dummy_key, &logger);
 		monitor.provide_latest_counterparty_commitment_tx(dummy_txid, preimages_slice_to_htlc_outputs!(preimages[18..20]), 281474976710652, dummy_key, &logger);
 		for &(ref preimage, ref hash) in preimages.iter() {
-			monitor.provide_payment_preimage(hash, preimage, &broadcaster, &fee_estimator, &logger);
+			let bounded_fee_estimator = LowerBoundedFeeEstimator::new(&fee_estimator);
+			monitor.provide_payment_preimage(hash, preimage, &broadcaster, &bounded_fee_estimator, &logger);
 		}
 
 		// Now provide a secret, pruning preimages 10-15

lightning/src/chain/onchaintx.rs

@@ -24,7 +24,7 @@ use bitcoin::secp256k1;
 use ln::msgs::DecodeError;
 use ln::PaymentPreimage;
 use ln::chan_utils::{ChannelTransactionParameters, HolderCommitmentTransaction};
-use chain::chaininterface::{FeeEstimator, BroadcasterInterface};
+use chain::chaininterface::{FeeEstimator, BroadcasterInterface, LowerBoundedFeeEstimator};
 use chain::channelmonitor::{ANTI_REORG_DELAY, CLTV_SHARED_CLAIM_BUFFER};
 use chain::keysinterface::{Sign, KeysInterface};
 use chain::package::PackageTemplate;
@@ -377,7 +377,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 	/// (CSV or CLTV following cases). In case of high-fee spikes, claim tx may stuck in the mempool, so you need to bump its feerate quickly using Replace-By-Fee or Child-Pay-For-Parent.
 	/// Panics if there are signing errors, because signing operations in reaction to on-chain events
 	/// are not expected to fail, and if they do, we may lose funds.
-	fn generate_claim_tx<F: Deref, L: Deref>(&mut self, cur_height: u32, cached_request: &PackageTemplate, fee_estimator: &F, logger: &L) -> Option<(Option<u32>, u64, Transaction)>
+	fn generate_claim_tx<F: Deref, L: Deref>(&mut self, cur_height: u32, cached_request: &PackageTemplate, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L) -> Option<(Option<u32>, u64, Transaction)>
 		where F::Target: FeeEstimator,
 					L::Target: Logger,
 	{
@@ -415,7 +415,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 	/// `conf_height` represents the height at which the transactions in `txn_matched` were
 	/// confirmed. This does not need to equal the current blockchain tip height, which should be
 	/// provided via `cur_height`, however it must never be higher than `cur_height`.
-	pub(crate) fn update_claims_view<B: Deref, F: Deref, L: Deref>(&mut self, txn_matched: &[&Transaction], requests: Vec<PackageTemplate>, conf_height: u32, cur_height: u32, broadcaster: &B, fee_estimator: &F, logger: &L)
+	pub(crate) fn update_claims_view<B: Deref, F: Deref, L: Deref>(&mut self, txn_matched: &[&Transaction], requests: Vec<PackageTemplate>, conf_height: u32, cur_height: u32, broadcaster: &B, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L)
 		where B::Target: BroadcasterInterface,
 		      F::Target: FeeEstimator,
 					L::Target: Logger,
@@ -617,7 +617,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 		&mut self,
 		txid: &Txid,
 		broadcaster: B,
-		fee_estimator: F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: L,
 	) where
 		B::Target: BroadcasterInterface,
@@ -637,7 +637,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 		}
 	}
 
-	pub(crate) fn block_disconnected<B: Deref, F: Deref, L: Deref>(&mut self, height: u32, broadcaster: B, fee_estimator: F, logger: L)
+	pub(crate) fn block_disconnected<B: Deref, F: Deref, L: Deref>(&mut self, height: u32, broadcaster: B, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: L)
 		where B::Target: BroadcasterInterface,
 		      F::Target: FeeEstimator,
 					L::Target: Logger,
@@ -667,7 +667,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 			}
 		}
 		for (_, request) in bump_candidates.iter_mut() {
-			if let Some((new_timer, new_feerate, bump_tx)) = self.generate_claim_tx(height, &request, &&*fee_estimator, &&*logger) {
+			if let Some((new_timer, new_feerate, bump_tx)) = self.generate_claim_tx(height, &request, fee_estimator, &&*logger) {
 				request.set_timer(new_timer);
 				request.set_feerate(new_feerate);
 				log_info!(logger, "Broadcasting onchain {}", log_tx!(bump_tx));

lightning/src/chain/package.rs

@@ -38,6 +38,8 @@ use core::mem;
 use core::ops::Deref;
 use bitcoin::Witness;
 
+use super::chaininterface::LowerBoundedFeeEstimator;
+
 const MAX_ALLOC_SIZE: usize = 64*1024;
 
 
@@ -665,7 +667,7 @@ impl PackageTemplate {
 	/// Returns value in satoshis to be included as package outgoing output amount and feerate
 	/// which was used to generate the value. Will not return less than `dust_limit_sats` for the
 	/// value.
-	pub(crate) fn compute_package_output<F: Deref, L: Deref>(&self, predicted_weight: usize, dust_limit_sats: u64, fee_estimator: &F, logger: &L) -> Option<(u64, u64)>
+	pub(crate) fn compute_package_output<F: Deref, L: Deref>(&self, predicted_weight: usize, dust_limit_sats: u64, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L) -> Option<(u64, u64)>
 		where F::Target: FeeEstimator,
 		      L::Target: Logger,
 	{
@@ -772,7 +774,7 @@ impl Readable for PackageTemplate {
 /// If the proposed fee is less than the available spent output's values, we return the proposed
 /// fee and the corresponding updated feerate. If the proposed fee is equal or more than the
 /// available spent output's values, we return nothing
-fn compute_fee_from_spent_amounts<F: Deref, L: Deref>(input_amounts: u64, predicted_weight: usize, fee_estimator: &F, logger: &L) -> Option<(u64, u64)>
+fn compute_fee_from_spent_amounts<F: Deref, L: Deref>(input_amounts: u64, predicted_weight: usize, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L) -> Option<(u64, u64)>
 	where F::Target: FeeEstimator,
 	      L::Target: Logger,
 {
@@ -808,7 +810,7 @@ fn compute_fee_from_spent_amounts<F: Deref, L: Deref>(input_amounts: u64, predic
 /// attempt, use them. Otherwise, blindly bump the feerate by 25% of the previous feerate. We also
 /// verify that those bumping heuristics respect BIP125 rules 3) and 4) and if required adjust
 /// the new fee to meet the RBF policy requirement.
-fn feerate_bump<F: Deref, L: Deref>(predicted_weight: usize, input_amounts: u64, previous_feerate: u64, fee_estimator: &F, logger: &L) -> Option<(u64, u64)>
+fn feerate_bump<F: Deref, L: Deref>(predicted_weight: usize, input_amounts: u64, previous_feerate: u64, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L) -> Option<(u64, u64)>
 	where F::Target: FeeEstimator,
 	      L::Target: Logger,
 {