Merge pull request #2428 from waterson/create-channel-after-accept
[rust-lightning] / lightning / src / events / bump_transaction.rs
index dbe1b734e5642339045d89b16b3f9d31b39ba56e..4e7c3a224c29204d57d43220527ea9ba423b9620 100644 (file)
@@ -26,7 +26,7 @@ use crate::ln::chan_utils::{
 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;
 
@@ -102,9 +102,9 @@ impl AnchorDescriptor {
        }
 
        /// Derives the channel signer required to sign the anchor input.
-       pub fn derive_channel_signer<SP: Deref>(&self, signer_provider: &SP) -> <SP::Target as SignerProvider>::Signer
+       pub fn derive_channel_signer<S: WriteableEcdsaChannelSigner, SP: Deref>(&self, signer_provider: &SP) -> S
        where
-               SP::Target: SignerProvider
+               SP::Target: SignerProvider<Signer = S>
        {
                let mut signer = signer_provider.derive_channel_signer(
                        self.channel_derivation_parameters.value_satoshis,
@@ -140,6 +140,15 @@ pub struct HTLCDescriptor {
 }
 
 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 {
@@ -202,9 +211,9 @@ impl HTLCDescriptor {
        }
 
        /// Derives the channel signer required to sign the HTLC input.
-       pub fn derive_channel_signer<SP: Deref>(&self, signer_provider: &SP) -> <SP::Target as SignerProvider>::Signer
+       pub fn derive_channel_signer<S: WriteableEcdsaChannelSigner, SP: Deref>(&self, signer_provider: &SP) -> S
        where
-               SP::Target: SignerProvider
+               SP::Target: SignerProvider<Signer = S>
        {
                let mut signer = signer_provider.derive_channel_signer(
                        self.channel_derivation_parameters.value_satoshis,
@@ -332,6 +341,7 @@ pub enum BumpTransactionEvent {
 /// 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,
@@ -345,7 +355,7 @@ pub struct Input {
 
 /// 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,
@@ -412,6 +422,7 @@ impl Utxo {
 
 /// 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.
@@ -455,12 +466,12 @@ pub trait CoinSelectionSource {
        /// 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
@@ -474,25 +485,34 @@ pub trait WalletSource {
        /// 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
@@ -512,6 +532,7 @@ impl<W: Deref> Wallet<W> where W::Target: WalletSource {
                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;
                                }
                        }
@@ -526,6 +547,7 @@ impl<W: Deref> Wallet<W> where W::Target: WalletSource {
                        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<_>>();
@@ -543,6 +565,8 @@ impl<W: Deref> Wallet<W> where W::Target: WalletSource {
                        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 {
@@ -559,6 +583,7 @@ impl<W: Deref> Wallet<W> where W::Target: WalletSource {
                );
                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 })
@@ -571,9 +596,13 @@ impl<W: Deref> Wallet<W> where W::Target: WalletSource {
        }
 }
 
-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()?;
@@ -589,6 +618,8 @@ impl<W: Deref> CoinSelectionSource for Wallet<W> where W::Target: WalletSource {
                        ((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,
@@ -600,7 +631,7 @@ impl<W: Deref> CoinSelectionSource for Wallet<W> where W::Target: WalletSource {
                        .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)
        }
 }
@@ -661,6 +692,7 @@ where
                        // 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(&[]),
@@ -688,13 +720,15 @@ where
                        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, &[], anchor_target_feerate_sat_per_1000_weight,
+                       claim_id, must_spend, &[], anchor_target_feerate_sat_per_1000_weight,
                )?;
 
                let mut anchor_tx = Transaction {
@@ -709,12 +743,15 @@ where
                                ANCHOR_INPUT_WITNESS_WEIGHT + EMPTY_SCRIPT_SIG_WEIGHT;
 
                self.process_coin_selection(&mut anchor_tx, coin_selection);
+               let anchor_txid = anchor_tx.txid();
 
                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)?;
+               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 = anchor_descriptor.tx_input_witness(&anchor_sig);
@@ -722,10 +759,14 @@ where
                #[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.
-                       assert!(expected_signed_tx_weight - (expected_signed_tx_weight / 100) <= signed_tx_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(())
        }
@@ -759,19 +800,26 @@ where
                        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, &htlc_tx.output, target_feerate_sat_per_1000_weight,
+                       claim_id, must_spend, &htlc_tx.output, target_feerate_sat_per_1000_weight,
                )?;
                #[cfg(debug_assertions)]
                let total_satisfaction_weight =
                        coin_selection.confirmed_utxos.iter().map(|utxo| utxo.satisfaction_weight).sum::<u64>() +
-                               must_spend.iter().map(|input| input.satisfaction_weight).sum::<u64>();
+                               must_spend_satisfaction_weight;
                self.process_coin_selection(&mut htlc_tx, coin_selection);
 
                #[cfg(debug_assertions)]
                let unsigned_tx_weight = htlc_tx.weight() as u64 - (htlc_tx.input.len() as u64 * EMPTY_SCRIPT_SIG_WEIGHT);
 
-               self.utxo_source.sign_tx(&mut htlc_tx)?;
+               log_debug!(self.logger, "Signing HTLC transaction {}", htlc_tx.txid());
+               htlc_tx = self.utxo_source.sign_tx(htlc_tx)?;
+
                let mut signers = BTreeMap::new();
                for (idx, htlc_descriptor) in htlc_descriptors.iter().enumerate() {
                        let signer = signers.entry(htlc_descriptor.channel_derivation_parameters.keys_id)
@@ -784,10 +832,13 @@ where
                #[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.
-                       assert!(expected_signed_tx_weight - (expected_signed_tx_weight / 100) <= signed_tx_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(())
        }
@@ -799,6 +850,8 @@ where
                                claim_id, package_target_feerate_sat_per_1000_weight, commitment_tx,
                                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,
@@ -810,6 +863,8 @@ where
                        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,
                                ) {