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Merge pull request #2625 from tnull/2023-09-moar-tests-n-fixes
[rust-lightning] / lightning / src / events / bump_transaction.rs
1 // This file is Copyright its original authors, visible in version control
2 // history.
3 //
4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7 // You may not use this file except in accordance with one or both of these
8 // licenses.
9
10 //! Utilities for bumping transactions originating from [`Event`]s.
11 //!
12 //! [`Event`]: crate::events::Event
13
14 use alloc::collections::BTreeMap;
15 use core::ops::Deref;
16
17 use crate::chain::chaininterface::{BroadcasterInterface, fee_for_weight};
18 use crate::chain::ClaimId;
19 use crate::io_extras::sink;
20 use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI;
21 use crate::ln::chan_utils;
22 use crate::ln::chan_utils::{
23         ANCHOR_INPUT_WITNESS_WEIGHT, HTLC_SUCCESS_INPUT_ANCHOR_WITNESS_WEIGHT,
24         HTLC_TIMEOUT_INPUT_ANCHOR_WITNESS_WEIGHT, ChannelTransactionParameters, HTLCOutputInCommitment
25 };
26 use crate::ln::features::ChannelTypeFeatures;
27 use crate::ln::PaymentPreimage;
28 use crate::prelude::*;
29 use crate::sign::{EcdsaChannelSigner, SignerProvider, WriteableEcdsaChannelSigner, P2WPKH_WITNESS_WEIGHT};
30 use crate::sync::Mutex;
31 use crate::util::logger::Logger;
32
33 use bitcoin::{OutPoint, PackedLockTime, PubkeyHash, Sequence, Script, Transaction, Txid, TxIn, TxOut, Witness, WPubkeyHash};
34 use bitcoin::blockdata::constants::WITNESS_SCALE_FACTOR;
35 use bitcoin::consensus::Encodable;
36 use bitcoin::secp256k1;
37 use bitcoin::secp256k1::{PublicKey, Secp256k1};
38 use bitcoin::secp256k1::ecdsa::Signature;
39
40 const EMPTY_SCRIPT_SIG_WEIGHT: u64 = 1 /* empty script_sig */ * WITNESS_SCALE_FACTOR as u64;
41
42 const BASE_INPUT_SIZE: u64 = 32 /* txid */ + 4 /* vout */ + 4 /* sequence */;
43
44 const BASE_INPUT_WEIGHT: u64 = BASE_INPUT_SIZE * WITNESS_SCALE_FACTOR as u64;
45
46 /// The parameters required to derive a channel signer via [`SignerProvider`].
47 #[derive(Clone, Debug, PartialEq, Eq)]
48 pub struct ChannelDerivationParameters {
49         /// The value in satoshis of the channel we're attempting to spend the anchor output of.
50         pub value_satoshis: u64,
51         /// The unique identifier to re-derive the signer for the associated channel.
52         pub keys_id: [u8; 32],
53         /// The necessary channel parameters that need to be provided to the re-derived signer through
54         /// [`ChannelSigner::provide_channel_parameters`].
55         ///
56         /// [`ChannelSigner::provide_channel_parameters`]: crate::sign::ChannelSigner::provide_channel_parameters
57         pub transaction_parameters: ChannelTransactionParameters,
58 }
59
60 impl_writeable_tlv_based!(ChannelDerivationParameters, {
61     (0, value_satoshis, required),
62     (2, keys_id, required),
63     (4, transaction_parameters, required),
64 });
65
66 /// A descriptor used to sign for a commitment transaction's anchor output.
67 #[derive(Clone, Debug, PartialEq, Eq)]
68 pub struct AnchorDescriptor {
69         /// The parameters required to derive the signer for the anchor input.
70         pub channel_derivation_parameters: ChannelDerivationParameters,
71         /// The transaction input's outpoint corresponding to the commitment transaction's anchor
72         /// output.
73         pub outpoint: OutPoint,
74 }
75
76 impl AnchorDescriptor {
77         /// Returns the UTXO to be spent by the anchor input, which can be obtained via
78         /// [`Self::unsigned_tx_input`].
79         pub fn previous_utxo(&self) -> TxOut {
80                 TxOut {
81                         script_pubkey: self.witness_script().to_v0_p2wsh(),
82                         value: ANCHOR_OUTPUT_VALUE_SATOSHI,
83                 }
84         }
85
86         /// Returns the unsigned transaction input spending the anchor output in the commitment
87         /// transaction.
88         pub fn unsigned_tx_input(&self) -> TxIn {
89                 TxIn {
90                         previous_output: self.outpoint.clone(),
91                         script_sig: Script::new(),
92                         sequence: Sequence::ENABLE_RBF_NO_LOCKTIME,
93                         witness: Witness::new(),
94                 }
95         }
96
97         /// Returns the witness script of the anchor output in the commitment transaction.
98         pub fn witness_script(&self) -> Script {
99                 let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
100                 chan_utils::get_anchor_redeemscript(&channel_params.broadcaster_pubkeys().funding_pubkey)
101         }
102
103         /// Returns the fully signed witness required to spend the anchor output in the commitment
104         /// transaction.
105         pub fn tx_input_witness(&self, signature: &Signature) -> Witness {
106                 let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
107                 chan_utils::build_anchor_input_witness(&channel_params.broadcaster_pubkeys().funding_pubkey, signature)
108         }
109
110         /// Derives the channel signer required to sign the anchor input.
111         pub fn derive_channel_signer<S: WriteableEcdsaChannelSigner, SP: Deref>(&self, signer_provider: &SP) -> S
112         where
113                 SP::Target: SignerProvider<Signer = S>
114         {
115                 let mut signer = signer_provider.derive_channel_signer(
116                         self.channel_derivation_parameters.value_satoshis,
117                         self.channel_derivation_parameters.keys_id,
118                 );
119                 signer.provide_channel_parameters(&self.channel_derivation_parameters.transaction_parameters);
120                 signer
121         }
122 }
123
124 /// A descriptor used to sign for a commitment transaction's HTLC output.
125 #[derive(Clone, Debug, PartialEq, Eq)]
126 pub struct HTLCDescriptor {
127         /// The parameters required to derive the signer for the HTLC input.
128         pub channel_derivation_parameters: ChannelDerivationParameters,
129         /// The txid of the commitment transaction in which the HTLC output lives.
130         pub commitment_txid: Txid,
131         /// The number of the commitment transaction in which the HTLC output lives.
132         pub per_commitment_number: u64,
133         /// The key tweak corresponding to the number of the commitment transaction in which the HTLC
134         /// output lives. This tweak is applied to all the basepoints for both parties in the channel to
135         /// arrive at unique keys per commitment.
136         ///
137         /// See <https://github.com/lightning/bolts/blob/master/03-transactions.md#keys> for more info.
138         pub per_commitment_point: PublicKey,
139         /// The details of the HTLC as it appears in the commitment transaction.
140         pub htlc: HTLCOutputInCommitment,
141         /// The preimage, if `Some`, to claim the HTLC output with. If `None`, the timeout path must be
142         /// taken.
143         pub preimage: Option<PaymentPreimage>,
144         /// The counterparty's signature required to spend the HTLC output.
145         pub counterparty_sig: Signature
146 }
147
148 impl_writeable_tlv_based!(HTLCDescriptor, {
149     (0, channel_derivation_parameters, required),
150     (2, commitment_txid, required),
151     (4, per_commitment_number, required),
152     (6, per_commitment_point, required),
153     (8, htlc, required),
154     (10, preimage, option),
155     (12, counterparty_sig, required),
156 });
157
158 impl HTLCDescriptor {
159         /// Returns the outpoint of the HTLC output in the commitment transaction. This is the outpoint
160         /// being spent by the HTLC input in the HTLC transaction.
161         pub fn outpoint(&self) -> OutPoint {
162                 OutPoint {
163                         txid: self.commitment_txid,
164                         vout: self.htlc.transaction_output_index.unwrap(),
165                 }
166         }
167
168         /// Returns the UTXO to be spent by the HTLC input, which can be obtained via
169         /// [`Self::unsigned_tx_input`].
170         pub fn previous_utxo<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> TxOut {
171                 TxOut {
172                         script_pubkey: self.witness_script(secp).to_v0_p2wsh(),
173                         value: self.htlc.amount_msat / 1000,
174                 }
175         }
176
177         /// Returns the unsigned transaction input spending the HTLC output in the commitment
178         /// transaction.
179         pub fn unsigned_tx_input(&self) -> TxIn {
180                 chan_utils::build_htlc_input(&self.commitment_txid, &self.htlc, &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies())
181         }
182
183         /// Returns the delayed output created as a result of spending the HTLC output in the commitment
184         /// transaction.
185         pub fn tx_output<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> TxOut {
186                 let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
187                 let broadcaster_keys = channel_params.broadcaster_pubkeys();
188                 let counterparty_keys = channel_params.countersignatory_pubkeys();
189                 let broadcaster_delayed_key = chan_utils::derive_public_key(
190                         secp, &self.per_commitment_point, &broadcaster_keys.delayed_payment_basepoint
191                 );
192                 let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
193                         secp, &self.per_commitment_point, &counterparty_keys.revocation_basepoint
194                 );
195                 chan_utils::build_htlc_output(
196                         0 /* feerate_per_kw */, channel_params.contest_delay(), &self.htlc,
197                         &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies(), &broadcaster_delayed_key, &counterparty_revocation_key
198                 )
199         }
200
201         /// Returns the witness script of the HTLC output in the commitment transaction.
202         pub fn witness_script<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> Script {
203                 let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
204                 let broadcaster_keys = channel_params.broadcaster_pubkeys();
205                 let counterparty_keys = channel_params.countersignatory_pubkeys();
206                 let broadcaster_htlc_key = chan_utils::derive_public_key(
207                         secp, &self.per_commitment_point, &broadcaster_keys.htlc_basepoint
208                 );
209                 let counterparty_htlc_key = chan_utils::derive_public_key(
210                         secp, &self.per_commitment_point, &counterparty_keys.htlc_basepoint
211                 );
212                 let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
213                         secp, &self.per_commitment_point, &counterparty_keys.revocation_basepoint
214                 );
215                 chan_utils::get_htlc_redeemscript_with_explicit_keys(
216                         &self.htlc, &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies(), &broadcaster_htlc_key, &counterparty_htlc_key,
217                         &counterparty_revocation_key,
218                 )
219         }
220
221         /// Returns the fully signed witness required to spend the HTLC output in the commitment
222         /// transaction.
223         pub fn tx_input_witness(&self, signature: &Signature, witness_script: &Script) -> Witness {
224                 chan_utils::build_htlc_input_witness(
225                         signature, &self.counterparty_sig, &self.preimage, witness_script, &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies() /* opt_anchors */
226                 )
227         }
228
229         /// Derives the channel signer required to sign the HTLC input.
230         pub fn derive_channel_signer<S: WriteableEcdsaChannelSigner, SP: Deref>(&self, signer_provider: &SP) -> S
231         where
232                 SP::Target: SignerProvider<Signer = S>
233         {
234                 let mut signer = signer_provider.derive_channel_signer(
235                         self.channel_derivation_parameters.value_satoshis,
236                         self.channel_derivation_parameters.keys_id,
237                 );
238                 signer.provide_channel_parameters(&self.channel_derivation_parameters.transaction_parameters);
239                 signer
240         }
241 }
242
243 /// Represents the different types of transactions, originating from LDK, to be bumped.
244 #[derive(Clone, Debug, PartialEq, Eq)]
245 pub enum BumpTransactionEvent {
246         /// Indicates that a channel featuring anchor outputs is to be closed by broadcasting the local
247         /// commitment transaction. Since commitment transactions have a static feerate pre-agreed upon,
248         /// they may need additional fees to be attached through a child transaction using the popular
249         /// [Child-Pays-For-Parent](https://bitcoinops.org/en/topics/cpfp) fee bumping technique. This
250         /// child transaction must include the anchor input described within `anchor_descriptor` along
251         /// with additional inputs to meet the target feerate. Failure to meet the target feerate
252         /// decreases the confirmation odds of the transaction package (which includes the commitment
253         /// and child anchor transactions), possibly resulting in a loss of funds. Once the transaction
254         /// is constructed, it must be fully signed for and broadcast by the consumer of the event
255         /// along with the `commitment_tx` enclosed. Note that the `commitment_tx` must always be
256         /// broadcast first, as the child anchor transaction depends on it.
257         ///
258         /// The consumer should be able to sign for any of the additional inputs included within the
259         /// child anchor transaction. To sign its anchor input, an [`EcdsaChannelSigner`] should be
260         /// re-derived through [`AnchorDescriptor::derive_channel_signer`]. The anchor input signature
261         /// can be computed with [`EcdsaChannelSigner::sign_holder_anchor_input`], which can then be
262         /// provided to [`build_anchor_input_witness`] along with the `funding_pubkey` to obtain the
263         /// full witness required to spend.
264         ///
265         /// It is possible to receive more than one instance of this event if a valid child anchor
266         /// transaction is never broadcast or is but not with a sufficient fee to be mined. Care should
267         /// be taken by the consumer of the event to ensure any future iterations of the child anchor
268         /// transaction adhere to the [Replace-By-Fee
269         /// rules](https://github.com/bitcoin/bitcoin/blob/master/doc/policy/mempool-replacements.md)
270         /// for fee bumps to be accepted into the mempool, and eventually the chain. As the frequency of
271         /// these events is not user-controlled, users may ignore/drop the event if they are no longer
272         /// able to commit external confirmed funds to the child anchor transaction.
273         ///
274         /// The set of `pending_htlcs` on the commitment transaction to be broadcast can be inspected to
275         /// determine whether a significant portion of the channel's funds are allocated to HTLCs,
276         /// enabling users to make their own decisions regarding the importance of the commitment
277         /// transaction's confirmation. Note that this is not required, but simply exists as an option
278         /// for users to override LDK's behavior. On commitments with no HTLCs (indicated by those with
279         /// an empty `pending_htlcs`), confirmation of the commitment transaction can be considered to
280         /// be not urgent.
281         ///
282         /// [`EcdsaChannelSigner`]: crate::sign::EcdsaChannelSigner
283         /// [`EcdsaChannelSigner::sign_holder_anchor_input`]: crate::sign::EcdsaChannelSigner::sign_holder_anchor_input
284         /// [`build_anchor_input_witness`]: crate::ln::chan_utils::build_anchor_input_witness
285         ChannelClose {
286                 /// The unique identifier for the claim of the anchor output in the commitment transaction.
287                 ///
288                 /// The identifier must map to the set of external UTXOs assigned to the claim, such that
289                 /// they can be reused when a new claim with the same identifier needs to be made, resulting
290                 /// in a fee-bumping attempt.
291                 claim_id: ClaimId,
292                 /// The target feerate that the transaction package, which consists of the commitment
293                 /// transaction and the to-be-crafted child anchor transaction, must meet.
294                 package_target_feerate_sat_per_1000_weight: u32,
295                 /// The channel's commitment transaction to bump the fee of. This transaction should be
296                 /// broadcast along with the anchor transaction constructed as a result of consuming this
297                 /// event.
298                 commitment_tx: Transaction,
299                 /// The absolute fee in satoshis of the commitment transaction. This can be used along the
300                 /// with weight of the commitment transaction to determine its feerate.
301                 commitment_tx_fee_satoshis: u64,
302                 /// The descriptor to sign the anchor input of the anchor transaction constructed as a
303                 /// result of consuming this event.
304                 anchor_descriptor: AnchorDescriptor,
305                 /// The set of pending HTLCs on the commitment transaction that need to be resolved once the
306                 /// commitment transaction confirms.
307                 pending_htlcs: Vec<HTLCOutputInCommitment>,
308         },
309         /// Indicates that a channel featuring anchor outputs has unilaterally closed on-chain by a
310         /// holder commitment transaction and its HTLC(s) need to be resolved on-chain. With the
311         /// zero-HTLC-transaction-fee variant of anchor outputs, the pre-signed HTLC
312         /// transactions have a zero fee, thus requiring additional inputs and/or outputs to be attached
313         /// for a timely confirmation within the chain. These additional inputs and/or outputs must be
314         /// appended to the resulting HTLC transaction to meet the target feerate. Failure to meet the
315         /// target feerate decreases the confirmation odds of the transaction, possibly resulting in a
316         /// loss of funds. Once the transaction meets the target feerate, it must be signed for and
317         /// broadcast by the consumer of the event.
318         ///
319         /// The consumer should be able to sign for any of the non-HTLC inputs added to the resulting
320         /// HTLC transaction. To sign HTLC inputs, an [`EcdsaChannelSigner`] should be re-derived
321         /// through [`HTLCDescriptor::derive_channel_signer`]. Each HTLC input's signature can be
322         /// computed with [`EcdsaChannelSigner::sign_holder_htlc_transaction`], which can then be
323         /// provided to [`HTLCDescriptor::tx_input_witness`] to obtain the fully signed witness required
324         /// to spend.
325         ///
326         /// It is possible to receive more than one instance of this event if a valid HTLC transaction
327         /// is never broadcast or is but not with a sufficient fee to be mined. Care should be taken by
328         /// the consumer of the event to ensure any future iterations of the HTLC transaction adhere to
329         /// the [Replace-By-Fee
330         /// rules](https://github.com/bitcoin/bitcoin/blob/master/doc/policy/mempool-replacements.md)
331         /// for fee bumps to be accepted into the mempool, and eventually the chain. As the frequency of
332         /// these events is not user-controlled, users may ignore/drop the event if either they are no
333         /// longer able to commit external confirmed funds to the HTLC transaction or the fee committed
334         /// to the HTLC transaction is greater in value than the HTLCs being claimed.
335         ///
336         /// [`EcdsaChannelSigner`]: crate::sign::EcdsaChannelSigner
337         /// [`EcdsaChannelSigner::sign_holder_htlc_transaction`]: crate::sign::EcdsaChannelSigner::sign_holder_htlc_transaction
338         /// [`HTLCDescriptor::tx_input_witness`]: HTLCDescriptor::tx_input_witness
339         HTLCResolution {
340                 /// The unique identifier for the claim of the HTLCs in the confirmed commitment
341                 /// transaction.
342                 ///
343                 /// The identifier must map to the set of external UTXOs assigned to the claim, such that
344                 /// they can be reused when a new claim with the same identifier needs to be made, resulting
345                 /// in a fee-bumping attempt.
346                 claim_id: ClaimId,
347                 /// The target feerate that the resulting HTLC transaction must meet.
348                 target_feerate_sat_per_1000_weight: u32,
349                 /// The set of pending HTLCs on the confirmed commitment that need to be claimed, preferably
350                 /// by the same transaction.
351                 htlc_descriptors: Vec<HTLCDescriptor>,
352                 /// The locktime required for the resulting HTLC transaction.
353                 tx_lock_time: PackedLockTime,
354         },
355 }
356
357 /// An input that must be included in a transaction when performing coin selection through
358 /// [`CoinSelectionSource::select_confirmed_utxos`]. It is guaranteed to be a SegWit input, so it
359 /// must have an empty [`TxIn::script_sig`] when spent.
360 #[derive(Clone, Debug, Hash, PartialOrd, Ord, PartialEq, Eq)]
361 pub struct Input {
362         /// The unique identifier of the input.
363         pub outpoint: OutPoint,
364         /// The UTXO being spent by the input.
365         pub previous_utxo: TxOut,
366         /// The upper-bound weight consumed by the input's full [`TxIn::script_sig`] and
367         /// [`TxIn::witness`], each with their lengths included, required to satisfy the output's
368         /// script.
369         pub satisfaction_weight: u64,
370 }
371
372 /// An unspent transaction output that is available to spend resulting from a successful
373 /// [`CoinSelection`] attempt.
374 #[derive(Clone, Debug, Hash, PartialOrd, Ord, PartialEq, Eq)]
375 pub struct Utxo {
376         /// The unique identifier of the output.
377         pub outpoint: OutPoint,
378         /// The output to spend.
379         pub output: TxOut,
380         /// The upper-bound weight consumed by the input's full [`TxIn::script_sig`] and [`TxIn::witness`], each
381         /// with their lengths included, required to satisfy the output's script. The weight consumed by
382         /// the input's `script_sig` must account for [`WITNESS_SCALE_FACTOR`].
383         pub satisfaction_weight: u64,
384 }
385
386 impl Utxo {
387         /// Returns a `Utxo` with the `satisfaction_weight` estimate for a legacy P2PKH output.
388         pub fn new_p2pkh(outpoint: OutPoint, value: u64, pubkey_hash: &PubkeyHash) -> Self {
389                 let script_sig_size = 1 /* script_sig length */ +
390                         1 /* OP_PUSH73 */ +
391                         73 /* sig including sighash flag */ +
392                         1 /* OP_PUSH33 */ +
393                         33 /* pubkey */;
394                 Self {
395                         outpoint,
396                         output: TxOut {
397                                 value,
398                                 script_pubkey: Script::new_p2pkh(pubkey_hash),
399                         },
400                         satisfaction_weight: script_sig_size * WITNESS_SCALE_FACTOR as u64 + 1 /* empty witness */,
401                 }
402         }
403
404         /// Returns a `Utxo` with the `satisfaction_weight` estimate for a P2WPKH nested in P2SH output.
405         pub fn new_nested_p2wpkh(outpoint: OutPoint, value: u64, pubkey_hash: &WPubkeyHash) -> Self {
406                 let script_sig_size = 1 /* script_sig length */ +
407                         1 /* OP_0 */ +
408                         1 /* OP_PUSH20 */ +
409                         20 /* pubkey_hash */;
410                 Self {
411                         outpoint,
412                         output: TxOut {
413                                 value,
414                                 script_pubkey: Script::new_p2sh(&Script::new_v0_p2wpkh(pubkey_hash).script_hash()),
415                         },
416                         satisfaction_weight: script_sig_size * WITNESS_SCALE_FACTOR as u64 + P2WPKH_WITNESS_WEIGHT,
417                 }
418         }
419
420         /// Returns a `Utxo` with the `satisfaction_weight` estimate for a SegWit v0 P2WPKH output.
421         pub fn new_v0_p2wpkh(outpoint: OutPoint, value: u64, pubkey_hash: &WPubkeyHash) -> Self {
422                 Self {
423                         outpoint,
424                         output: TxOut {
425                                 value,
426                                 script_pubkey: Script::new_v0_p2wpkh(pubkey_hash),
427                         },
428                         satisfaction_weight: EMPTY_SCRIPT_SIG_WEIGHT + P2WPKH_WITNESS_WEIGHT,
429                 }
430         }
431 }
432
433 /// The result of a successful coin selection attempt for a transaction requiring additional UTXOs
434 /// to cover its fees.
435 #[derive(Clone, Debug)]
436 pub struct CoinSelection {
437         /// The set of UTXOs (with at least 1 confirmation) to spend and use within a transaction
438         /// requiring additional fees.
439         pub confirmed_utxos: Vec<Utxo>,
440         /// An additional output tracking whether any change remained after coin selection. This output
441         /// should always have a value above dust for its given `script_pubkey`. It should not be
442         /// spent until the transaction it belongs to confirms to ensure mempool descendant limits are
443         /// not met. This implies no other party should be able to spend it except us.
444         pub change_output: Option<TxOut>,
445 }
446
447 /// An abstraction over a bitcoin wallet that can perform coin selection over a set of UTXOs and can
448 /// sign for them. The coin selection method aims to mimic Bitcoin Core's `fundrawtransaction` RPC,
449 /// which most wallets should be able to satisfy. Otherwise, consider implementing [`WalletSource`],
450 /// which can provide a default implementation of this trait when used with [`Wallet`].
451 pub trait CoinSelectionSource {
452         /// Performs coin selection of a set of UTXOs, with at least 1 confirmation each, that are
453         /// available to spend. Implementations are free to pick their coin selection algorithm of
454         /// choice, as long as the following requirements are met:
455         ///
456         /// 1. `must_spend` contains a set of [`Input`]s that must be included in the transaction
457         ///    throughout coin selection, but must not be returned as part of the result.
458         /// 2. `must_pay_to` contains a set of [`TxOut`]s that must be included in the transaction
459         ///    throughout coin selection. In some cases, like when funding an anchor transaction, this
460         ///    set is empty. Implementations should ensure they handle this correctly on their end,
461         ///    e.g., Bitcoin Core's `fundrawtransaction` RPC requires at least one output to be
462         ///    provided, in which case a zero-value empty OP_RETURN output can be used instead.
463         /// 3. Enough inputs must be selected/contributed for the resulting transaction (including the
464         ///    inputs and outputs noted above) to meet `target_feerate_sat_per_1000_weight`.
465         ///
466         /// Implementations must take note that [`Input::satisfaction_weight`] only tracks the weight of
467         /// the input's `script_sig` and `witness`. Some wallets, like Bitcoin Core's, may require
468         /// providing the full input weight. Failing to do so may lead to underestimating fee bumps and
469         /// delaying block inclusion.
470         ///
471         /// The `claim_id` must map to the set of external UTXOs assigned to the claim, such that they
472         /// can be re-used within new fee-bumped iterations of the original claiming transaction,
473         /// ensuring that claims don't double spend each other. If a specific `claim_id` has never had a
474         /// transaction associated with it, and all of the available UTXOs have already been assigned to
475         /// other claims, implementations must be willing to double spend their UTXOs. The choice of
476         /// which UTXOs to double spend is left to the implementation, but it must strive to keep the
477         /// set of other claims being double spent to a minimum.
478         fn select_confirmed_utxos(
479                 &self, claim_id: ClaimId, must_spend: Vec<Input>, must_pay_to: &[TxOut],
480                 target_feerate_sat_per_1000_weight: u32,
481         ) -> Result<CoinSelection, ()>;
482         /// Signs and provides the full witness for all inputs within the transaction known to the
483         /// trait (i.e., any provided via [`CoinSelectionSource::select_confirmed_utxos`]).
484         fn sign_tx(&self, tx: Transaction) -> Result<Transaction, ()>;
485 }
486
487 /// An alternative to [`CoinSelectionSource`] that can be implemented and used along [`Wallet`] to
488 /// provide a default implementation to [`CoinSelectionSource`].
489 pub trait WalletSource {
490         /// Returns all UTXOs, with at least 1 confirmation each, that are available to spend.
491         fn list_confirmed_utxos(&self) -> Result<Vec<Utxo>, ()>;
492         /// Returns a script to use for change above dust resulting from a successful coin selection
493         /// attempt.
494         fn get_change_script(&self) -> Result<Script, ()>;
495         /// Signs and provides the full [`TxIn::script_sig`] and [`TxIn::witness`] for all inputs within
496         /// the transaction known to the wallet (i.e., any provided via
497         /// [`WalletSource::list_confirmed_utxos`]).
498         fn sign_tx(&self, tx: Transaction) -> Result<Transaction, ()>;
499 }
500
501 /// A wrapper over [`WalletSource`] that implements [`CoinSelection`] by preferring UTXOs that would
502 /// avoid conflicting double spends. If not enough UTXOs are available to do so, conflicting double
503 /// spends may happen.
504 pub struct Wallet<W: Deref, L: Deref>
505 where
506         W::Target: WalletSource,
507         L::Target: Logger
508 {
509         source: W,
510         logger: L,
511         // TODO: Do we care about cleaning this up once the UTXOs have a confirmed spend? We can do so
512         // by checking whether any UTXOs that exist in the map are no longer returned in
513         // `list_confirmed_utxos`.
514         locked_utxos: Mutex<HashMap<OutPoint, ClaimId>>,
515 }
516
517 impl<W: Deref, L: Deref> Wallet<W, L>
518 where
519         W::Target: WalletSource,
520         L::Target: Logger
521 {
522         /// Returns a new instance backed by the given [`WalletSource`] that serves as an implementation
523         /// of [`CoinSelectionSource`].
524         pub fn new(source: W, logger: L) -> Self {
525                 Self { source, logger, locked_utxos: Mutex::new(HashMap::new()) }
526         }
527
528         /// Performs coin selection on the set of UTXOs obtained from
529         /// [`WalletSource::list_confirmed_utxos`]. Its algorithm can be described as "smallest
530         /// above-dust-after-spend first", with a slight twist: we may skip UTXOs that are above dust at
531         /// the target feerate after having spent them in a separate claim transaction if
532         /// `force_conflicting_utxo_spend` is unset to avoid producing conflicting transactions. If
533         /// `tolerate_high_network_feerates` is set, we'll attempt to spend UTXOs that contribute at
534         /// least 1 satoshi at the current feerate, otherwise, we'll only attempt to spend those which
535         /// contribute at least twice their fee.
536         fn select_confirmed_utxos_internal(
537                 &self, utxos: &[Utxo], claim_id: ClaimId, force_conflicting_utxo_spend: bool,
538                 tolerate_high_network_feerates: bool, target_feerate_sat_per_1000_weight: u32,
539                 preexisting_tx_weight: u64, input_amount_sat: u64, target_amount_sat: u64,
540         ) -> Result<CoinSelection, ()> {
541                 let mut locked_utxos = self.locked_utxos.lock().unwrap();
542                 let mut eligible_utxos = utxos.iter().filter_map(|utxo| {
543                         if let Some(utxo_claim_id) = locked_utxos.get(&utxo.outpoint) {
544                                 if *utxo_claim_id != claim_id && !force_conflicting_utxo_spend {
545                                         log_trace!(self.logger, "Skipping UTXO {} to prevent conflicting spend", utxo.outpoint);
546                                         return None;
547                                 }
548                         }
549                         let fee_to_spend_utxo = fee_for_weight(
550                                 target_feerate_sat_per_1000_weight, BASE_INPUT_WEIGHT as u64 + utxo.satisfaction_weight,
551                         );
552                         let should_spend = if tolerate_high_network_feerates {
553                                 utxo.output.value > fee_to_spend_utxo
554                         } else {
555                                 utxo.output.value >= fee_to_spend_utxo * 2
556                         };
557                         if should_spend {
558                                 Some((utxo, fee_to_spend_utxo))
559                         } else {
560                                 log_trace!(self.logger, "Skipping UTXO {} due to dust proximity after spend", utxo.outpoint);
561                                 None
562                         }
563                 }).collect::<Vec<_>>();
564                 eligible_utxos.sort_unstable_by_key(|(utxo, _)| utxo.output.value);
565
566                 let mut selected_amount = input_amount_sat;
567                 let mut total_fees = fee_for_weight(target_feerate_sat_per_1000_weight, preexisting_tx_weight);
568                 let mut selected_utxos = Vec::new();
569                 for (utxo, fee_to_spend_utxo) in eligible_utxos {
570                         if selected_amount >= target_amount_sat + total_fees {
571                                 break;
572                         }
573                         selected_amount += utxo.output.value;
574                         total_fees += fee_to_spend_utxo;
575                         selected_utxos.push(utxo.clone());
576                 }
577                 if selected_amount < target_amount_sat + total_fees {
578                         log_debug!(self.logger, "Insufficient funds to meet target feerate {} sat/kW",
579                                 target_feerate_sat_per_1000_weight);
580                         return Err(());
581                 }
582                 for utxo in &selected_utxos {
583                         locked_utxos.insert(utxo.outpoint, claim_id);
584                 }
585                 core::mem::drop(locked_utxos);
586
587                 let remaining_amount = selected_amount - target_amount_sat - total_fees;
588                 let change_script = self.source.get_change_script()?;
589                 let change_output_fee = fee_for_weight(
590                         target_feerate_sat_per_1000_weight,
591                         (8 /* value */ + change_script.consensus_encode(&mut sink()).unwrap() as u64) *
592                                 WITNESS_SCALE_FACTOR as u64,
593                 );
594                 let change_output_amount = remaining_amount.saturating_sub(change_output_fee);
595                 let change_output = if change_output_amount < change_script.dust_value().to_sat() {
596                         log_debug!(self.logger, "Coin selection attempt did not yield change output");
597                         None
598                 } else {
599                         Some(TxOut { script_pubkey: change_script, value: change_output_amount })
600                 };
601
602                 Ok(CoinSelection {
603                         confirmed_utxos: selected_utxos,
604                         change_output,
605                 })
606         }
607 }
608
609 impl<W: Deref, L: Deref> CoinSelectionSource for Wallet<W, L>
610 where
611         W::Target: WalletSource,
612         L::Target: Logger
613 {
614         fn select_confirmed_utxos(
615                 &self, claim_id: ClaimId, must_spend: Vec<Input>, must_pay_to: &[TxOut],
616                 target_feerate_sat_per_1000_weight: u32,
617         ) -> Result<CoinSelection, ()> {
618                 let utxos = self.source.list_confirmed_utxos()?;
619                 // TODO: Use fee estimation utils when we upgrade to bitcoin v0.30.0.
620                 const BASE_TX_SIZE: u64 = 4 /* version */ + 1 /* input count */ + 1 /* output count */ + 4 /* locktime */;
621                 let total_output_size: u64 = must_pay_to.iter().map(|output|
622                         8 /* value */ + 1 /* script len */ + output.script_pubkey.len() as u64
623                 ).sum();
624                 let total_satisfaction_weight: u64 = must_spend.iter().map(|input| input.satisfaction_weight).sum();
625                 let total_input_weight = (BASE_INPUT_WEIGHT * must_spend.len() as u64) + total_satisfaction_weight;
626
627                 let preexisting_tx_weight = 2 /* segwit marker & flag */ + total_input_weight +
628                         ((BASE_TX_SIZE + total_output_size) * WITNESS_SCALE_FACTOR as u64);
629                 let input_amount_sat: u64 = must_spend.iter().map(|input| input.previous_utxo.value).sum();
630                 let target_amount_sat = must_pay_to.iter().map(|output| output.value).sum();
631                 let do_coin_selection = |force_conflicting_utxo_spend: bool, tolerate_high_network_feerates: bool| {
632                         log_debug!(self.logger, "Attempting coin selection targeting {} sat/kW (force_conflicting_utxo_spend = {}, tolerate_high_network_feerates = {})",
633                                 target_feerate_sat_per_1000_weight, force_conflicting_utxo_spend, tolerate_high_network_feerates);
634                         self.select_confirmed_utxos_internal(
635                                 &utxos, claim_id, force_conflicting_utxo_spend, tolerate_high_network_feerates,
636                                 target_feerate_sat_per_1000_weight, preexisting_tx_weight, input_amount_sat, target_amount_sat,
637                         )
638                 };
639                 do_coin_selection(false, false)
640                         .or_else(|_| do_coin_selection(false, true))
641                         .or_else(|_| do_coin_selection(true, false))
642                         .or_else(|_| do_coin_selection(true, true))
643         }
644
645         fn sign_tx(&self, tx: Transaction) -> Result<Transaction, ()> {
646                 self.source.sign_tx(tx)
647         }
648 }
649
650 /// A handler for [`Event::BumpTransaction`] events that sources confirmed UTXOs from a
651 /// [`CoinSelectionSource`] to fee bump transactions via Child-Pays-For-Parent (CPFP) or
652 /// Replace-By-Fee (RBF).
653 ///
654 /// [`Event::BumpTransaction`]: crate::events::Event::BumpTransaction
655 pub struct BumpTransactionEventHandler<B: Deref, C: Deref, SP: Deref, L: Deref>
656 where
657         B::Target: BroadcasterInterface,
658         C::Target: CoinSelectionSource,
659         SP::Target: SignerProvider,
660         L::Target: Logger,
661 {
662         broadcaster: B,
663         utxo_source: C,
664         signer_provider: SP,
665         logger: L,
666         secp: Secp256k1<secp256k1::All>,
667 }
668
669 impl<B: Deref, C: Deref, SP: Deref, L: Deref> BumpTransactionEventHandler<B, C, SP, L>
670 where
671         B::Target: BroadcasterInterface,
672         C::Target: CoinSelectionSource,
673         SP::Target: SignerProvider,
674         L::Target: Logger,
675 {
676         /// Returns a new instance capable of handling [`Event::BumpTransaction`] events.
677         ///
678         /// [`Event::BumpTransaction`]: crate::events::Event::BumpTransaction
679         pub fn new(broadcaster: B, utxo_source: C, signer_provider: SP, logger: L) -> Self {
680                 Self {
681                         broadcaster,
682                         utxo_source,
683                         signer_provider,
684                         logger,
685                         secp: Secp256k1::new(),
686                 }
687         }
688
689         /// Updates a transaction with the result of a successful coin selection attempt.
690         fn process_coin_selection(&self, tx: &mut Transaction, mut coin_selection: CoinSelection) {
691                 for utxo in coin_selection.confirmed_utxos.drain(..) {
692                         tx.input.push(TxIn {
693                                 previous_output: utxo.outpoint,
694                                 script_sig: Script::new(),
695                                 sequence: Sequence::ZERO,
696                                 witness: Witness::new(),
697                         });
698                 }
699                 if let Some(change_output) = coin_selection.change_output.take() {
700                         tx.output.push(change_output);
701                 } else if tx.output.is_empty() {
702                         // We weren't provided a change output, likely because the input set was a perfect
703                         // match, but we still need to have at least one output in the transaction for it to be
704                         // considered standard. We choose to go with an empty OP_RETURN as it is the cheapest
705                         // way to include a dummy output.
706                         log_debug!(self.logger, "Including dummy OP_RETURN output since an output is needed and a change output was not provided");
707                         tx.output.push(TxOut {
708                                 value: 0,
709                                 script_pubkey: Script::new_op_return(&[]),
710                         });
711                 }
712         }
713
714         /// Handles a [`BumpTransactionEvent::ChannelClose`] event variant by producing a fully-signed
715         /// transaction spending an anchor output of the commitment transaction to bump its fee and
716         /// broadcasts them to the network as a package.
717         fn handle_channel_close(
718                 &self, claim_id: ClaimId, package_target_feerate_sat_per_1000_weight: u32,
719                 commitment_tx: &Transaction, commitment_tx_fee_sat: u64, anchor_descriptor: &AnchorDescriptor,
720         ) -> Result<(), ()> {
721                 // Our commitment transaction already has fees allocated to it, so we should take them into
722                 // account. We do so by pretending the commitment tranasction's fee and weight are part of
723                 // the anchor input.
724                 let mut anchor_utxo = anchor_descriptor.previous_utxo();
725                 anchor_utxo.value += commitment_tx_fee_sat;
726                 let must_spend = vec![Input {
727                         outpoint: anchor_descriptor.outpoint,
728                         previous_utxo: anchor_utxo,
729                         satisfaction_weight: commitment_tx.weight() as u64 + ANCHOR_INPUT_WITNESS_WEIGHT + EMPTY_SCRIPT_SIG_WEIGHT,
730                 }];
731                 #[cfg(debug_assertions)]
732                 let must_spend_amount = must_spend.iter().map(|input| input.previous_utxo.value).sum::<u64>();
733
734                 log_debug!(self.logger, "Peforming coin selection for commitment package (commitment and anchor transaction) targeting {} sat/kW",
735                         package_target_feerate_sat_per_1000_weight);
736                 let coin_selection = self.utxo_source.select_confirmed_utxos(
737                         claim_id, must_spend, &[], package_target_feerate_sat_per_1000_weight,
738                 )?;
739
740                 let mut anchor_tx = Transaction {
741                         version: 2,
742                         lock_time: PackedLockTime::ZERO, // TODO: Use next best height.
743                         input: vec![anchor_descriptor.unsigned_tx_input()],
744                         output: vec![],
745                 };
746
747                 #[cfg(debug_assertions)]
748                 let total_satisfaction_weight = ANCHOR_INPUT_WITNESS_WEIGHT + EMPTY_SCRIPT_SIG_WEIGHT +
749                         coin_selection.confirmed_utxos.iter().map(|utxo| utxo.satisfaction_weight).sum::<u64>();
750                 #[cfg(debug_assertions)]
751                 let total_input_amount = must_spend_amount +
752                         coin_selection.confirmed_utxos.iter().map(|utxo| utxo.output.value).sum::<u64>();
753
754                 self.process_coin_selection(&mut anchor_tx, coin_selection);
755                 let anchor_txid = anchor_tx.txid();
756
757                 debug_assert_eq!(anchor_tx.output.len(), 1);
758                 #[cfg(debug_assertions)]
759                 let unsigned_tx_weight = anchor_tx.weight() as u64 - (anchor_tx.input.len() as u64 * EMPTY_SCRIPT_SIG_WEIGHT);
760
761                 log_debug!(self.logger, "Signing anchor transaction {}", anchor_txid);
762                 anchor_tx = self.utxo_source.sign_tx(anchor_tx)?;
763
764                 let signer = anchor_descriptor.derive_channel_signer(&self.signer_provider);
765                 let anchor_sig = signer.sign_holder_anchor_input(&anchor_tx, 0, &self.secp)?;
766                 anchor_tx.input[0].witness = anchor_descriptor.tx_input_witness(&anchor_sig);
767
768                 #[cfg(debug_assertions)] {
769                         let signed_tx_weight = anchor_tx.weight() as u64;
770                         let expected_signed_tx_weight = unsigned_tx_weight + total_satisfaction_weight;
771                         // Our estimate should be within a 1% error margin of the actual weight and we should
772                         // never underestimate.
773                         assert!(expected_signed_tx_weight >= signed_tx_weight &&
774                                 expected_signed_tx_weight - (expected_signed_tx_weight / 100) <= signed_tx_weight);
775
776                         let expected_package_fee = fee_for_weight(package_target_feerate_sat_per_1000_weight,
777                                 signed_tx_weight + commitment_tx.weight() as u64);
778                         let package_fee = total_input_amount -
779                                 anchor_tx.output.iter().map(|output| output.value).sum::<u64>();
780                         // Our fee should be within a 5% error margin of the expected fee based on the
781                         // feerate and transaction weight and we should never pay less than required.
782                         let fee_error_margin = expected_package_fee * 5 / 100;
783                         assert!(package_fee >= expected_package_fee &&
784                                 package_fee - fee_error_margin <= expected_package_fee);
785                 }
786
787                 log_info!(self.logger, "Broadcasting anchor transaction {} to bump channel close with txid {}",
788                         anchor_txid, commitment_tx.txid());
789                 self.broadcaster.broadcast_transactions(&[&commitment_tx, &anchor_tx]);
790                 Ok(())
791         }
792
793         /// Handles a [`BumpTransactionEvent::HTLCResolution`] event variant by producing a
794         /// fully-signed, fee-bumped HTLC transaction that is broadcast to the network.
795         fn handle_htlc_resolution(
796                 &self, claim_id: ClaimId, target_feerate_sat_per_1000_weight: u32,
797                 htlc_descriptors: &[HTLCDescriptor], tx_lock_time: PackedLockTime,
798         ) -> Result<(), ()> {
799                 let mut htlc_tx = Transaction {
800                         version: 2,
801                         lock_time: tx_lock_time,
802                         input: vec![],
803                         output: vec![],
804                 };
805                 let mut must_spend = Vec::with_capacity(htlc_descriptors.len());
806                 for htlc_descriptor in htlc_descriptors {
807                         let htlc_input = htlc_descriptor.unsigned_tx_input();
808                         must_spend.push(Input {
809                                 outpoint: htlc_input.previous_output.clone(),
810                                 previous_utxo: htlc_descriptor.previous_utxo(&self.secp),
811                                 satisfaction_weight: EMPTY_SCRIPT_SIG_WEIGHT + if htlc_descriptor.preimage.is_some() {
812                                         HTLC_SUCCESS_INPUT_ANCHOR_WITNESS_WEIGHT
813                                 } else {
814                                         HTLC_TIMEOUT_INPUT_ANCHOR_WITNESS_WEIGHT
815                                 },
816                         });
817                         htlc_tx.input.push(htlc_input);
818                         let htlc_output = htlc_descriptor.tx_output(&self.secp);
819                         htlc_tx.output.push(htlc_output);
820                 }
821
822                 log_debug!(self.logger, "Peforming coin selection for HTLC transaction targeting {} sat/kW",
823                         target_feerate_sat_per_1000_weight);
824
825                 #[cfg(debug_assertions)]
826                 let must_spend_satisfaction_weight =
827                         must_spend.iter().map(|input| input.satisfaction_weight).sum::<u64>();
828                 #[cfg(debug_assertions)]
829                 let must_spend_amount = must_spend.iter().map(|input| input.previous_utxo.value).sum::<u64>();
830
831                 let coin_selection = self.utxo_source.select_confirmed_utxos(
832                         claim_id, must_spend, &htlc_tx.output, target_feerate_sat_per_1000_weight,
833                 )?;
834
835                 #[cfg(debug_assertions)]
836                 let total_satisfaction_weight = must_spend_satisfaction_weight +
837                         coin_selection.confirmed_utxos.iter().map(|utxo| utxo.satisfaction_weight).sum::<u64>();
838                 #[cfg(debug_assertions)]
839                 let total_input_amount = must_spend_amount +
840                         coin_selection.confirmed_utxos.iter().map(|utxo| utxo.output.value).sum::<u64>();
841
842                 self.process_coin_selection(&mut htlc_tx, coin_selection);
843
844                 #[cfg(debug_assertions)]
845                 let unsigned_tx_weight = htlc_tx.weight() as u64 - (htlc_tx.input.len() as u64 * EMPTY_SCRIPT_SIG_WEIGHT);
846
847                 log_debug!(self.logger, "Signing HTLC transaction {}", htlc_tx.txid());
848                 htlc_tx = self.utxo_source.sign_tx(htlc_tx)?;
849
850                 let mut signers = BTreeMap::new();
851                 for (idx, htlc_descriptor) in htlc_descriptors.iter().enumerate() {
852                         let signer = signers.entry(htlc_descriptor.channel_derivation_parameters.keys_id)
853                                 .or_insert_with(|| htlc_descriptor.derive_channel_signer(&self.signer_provider));
854                         let htlc_sig = signer.sign_holder_htlc_transaction(&htlc_tx, idx, htlc_descriptor, &self.secp)?;
855                         let witness_script = htlc_descriptor.witness_script(&self.secp);
856                         htlc_tx.input[idx].witness = htlc_descriptor.tx_input_witness(&htlc_sig, &witness_script);
857                 }
858
859                 #[cfg(debug_assertions)] {
860                         let signed_tx_weight = htlc_tx.weight() as u64;
861                         let expected_signed_tx_weight = unsigned_tx_weight + total_satisfaction_weight;
862                         // Our estimate should be within a 1% error margin of the actual weight and we should
863                         // never underestimate.
864                         assert!(expected_signed_tx_weight >= signed_tx_weight &&
865                                 expected_signed_tx_weight - (expected_signed_tx_weight / 100) <= signed_tx_weight);
866
867                         let expected_signed_tx_fee = fee_for_weight(target_feerate_sat_per_1000_weight, signed_tx_weight);
868                         let signed_tx_fee = total_input_amount -
869                                 htlc_tx.output.iter().map(|output| output.value).sum::<u64>();
870                         // Our fee should be within a 5% error margin of the expected fee based on the
871                         // feerate and transaction weight and we should never pay less than required.
872                         let fee_error_margin = expected_signed_tx_fee * 5 / 100;
873                         assert!(signed_tx_fee >= expected_signed_tx_fee &&
874                                 signed_tx_fee - fee_error_margin <= expected_signed_tx_fee);
875                 }
876
877                 log_info!(self.logger, "Broadcasting {}", log_tx!(htlc_tx));
878                 self.broadcaster.broadcast_transactions(&[&htlc_tx]);
879                 Ok(())
880         }
881
882         /// Handles all variants of [`BumpTransactionEvent`].
883         pub fn handle_event(&self, event: &BumpTransactionEvent) {
884                 match event {
885                         BumpTransactionEvent::ChannelClose {
886                                 claim_id, package_target_feerate_sat_per_1000_weight, commitment_tx,
887                                 commitment_tx_fee_satoshis, anchor_descriptor, ..
888                         } => {
889                                 log_info!(self.logger, "Handling channel close bump (claim_id = {}, commitment_txid = {})",
890                                         log_bytes!(claim_id.0), commitment_tx.txid());
891                                 if let Err(_) = self.handle_channel_close(
892                                         *claim_id, *package_target_feerate_sat_per_1000_weight, commitment_tx,
893                                         *commitment_tx_fee_satoshis, anchor_descriptor,
894                                 ) {
895                                         log_error!(self.logger, "Failed bumping commitment transaction fee for {}",
896                                                 commitment_tx.txid());
897                                 }
898                         }
899                         BumpTransactionEvent::HTLCResolution {
900                                 claim_id, target_feerate_sat_per_1000_weight, htlc_descriptors, tx_lock_time,
901                         } => {
902                                 log_info!(self.logger, "Handling HTLC bump (claim_id = {}, htlcs_to_claim = {})",
903                                         log_bytes!(claim_id.0), log_iter!(htlc_descriptors.iter().map(|d| d.outpoint())));
904                                 if let Err(_) = self.handle_htlc_resolution(
905                                         *claim_id, *target_feerate_sat_per_1000_weight, htlc_descriptors, *tx_lock_time,
906                                 ) {
907                                         log_error!(self.logger, "Failed bumping HTLC transaction fee for commitment {}",
908                                                 htlc_descriptors[0].commitment_txid);
909                                 }
910                         }
911                 }
912         }
913 }