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[rust-lightning] / lightning / src / chain / package.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 //! Various utilities to assemble claimable outpoints in package of one or more transactions. Those
11 //! packages are attached metadata, guiding their aggregable or fee-bumping re-schedule. This file
12 //! also includes witness weight computation and fee computation methods.
13
14 use bitcoin::blockdata::constants::WITNESS_SCALE_FACTOR;
15 use bitcoin::blockdata::transaction::{TxOut,TxIn, Transaction, EcdsaSighashType};
16 use bitcoin::blockdata::transaction::OutPoint as BitcoinOutPoint;
17 use bitcoin::blockdata::script::Script;
18
19 use bitcoin::hash_types::Txid;
20
21 use bitcoin::secp256k1::{SecretKey,PublicKey};
22
23 use crate::ln::PaymentPreimage;
24 use crate::ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment};
25 use crate::ln::chan_utils;
26 use crate::ln::msgs::DecodeError;
27 use crate::chain::chaininterface::{FeeEstimator, ConfirmationTarget, MIN_RELAY_FEE_SAT_PER_1000_WEIGHT};
28 use crate::chain::keysinterface::WriteableEcdsaChannelSigner;
29 #[cfg(anchors)]
30 use crate::chain::onchaintx::ExternalHTLCClaim;
31 use crate::chain::onchaintx::OnchainTxHandler;
32 use crate::util::logger::Logger;
33 use crate::util::ser::{Readable, Writer, Writeable};
34
35 use crate::io;
36 use crate::prelude::*;
37 use core::cmp;
38 #[cfg(anchors)]
39 use core::convert::TryInto;
40 use core::mem;
41 use core::ops::Deref;
42 use bitcoin::{PackedLockTime, Sequence, Witness};
43
44 use super::chaininterface::LowerBoundedFeeEstimator;
45
46 const MAX_ALLOC_SIZE: usize = 64*1024;
47
48
49 pub(crate) fn weight_revoked_offered_htlc(opt_anchors: bool) -> u64 {
50         // number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
51         const WEIGHT_REVOKED_OFFERED_HTLC: u64 = 1 + 1 + 73 + 1 + 33 + 1 + 133;
52         const WEIGHT_REVOKED_OFFERED_HTLC_ANCHORS: u64 = WEIGHT_REVOKED_OFFERED_HTLC + 3; // + OP_1 + OP_CSV + OP_DROP
53         if opt_anchors { WEIGHT_REVOKED_OFFERED_HTLC_ANCHORS } else { WEIGHT_REVOKED_OFFERED_HTLC }
54 }
55
56 pub(crate) fn weight_revoked_received_htlc(opt_anchors: bool) -> u64 {
57         // number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
58         const WEIGHT_REVOKED_RECEIVED_HTLC: u64 = 1 + 1 + 73 + 1 + 33 + 1 +  139;
59         const WEIGHT_REVOKED_RECEIVED_HTLC_ANCHORS: u64 = WEIGHT_REVOKED_RECEIVED_HTLC + 3; // + OP_1 + OP_CSV + OP_DROP
60         if opt_anchors { WEIGHT_REVOKED_RECEIVED_HTLC_ANCHORS } else { WEIGHT_REVOKED_RECEIVED_HTLC }
61 }
62
63 pub(crate) fn weight_offered_htlc(opt_anchors: bool) -> u64 {
64         // number_of_witness_elements + sig_length + counterpartyhtlc_sig  + preimage_length + preimage + witness_script_length + witness_script
65         const WEIGHT_OFFERED_HTLC: u64 = 1 + 1 + 73 + 1 + 32 + 1 + 133;
66         const WEIGHT_OFFERED_HTLC_ANCHORS: u64 = WEIGHT_OFFERED_HTLC + 3; // + OP_1 + OP_CSV + OP_DROP
67         if opt_anchors { WEIGHT_OFFERED_HTLC_ANCHORS } else { WEIGHT_OFFERED_HTLC }
68 }
69
70 pub(crate) fn weight_received_htlc(opt_anchors: bool) -> u64 {
71         // number_of_witness_elements + sig_length + counterpartyhtlc_sig + empty_vec_length + empty_vec + witness_script_length + witness_script
72         const WEIGHT_RECEIVED_HTLC: u64 = 1 + 1 + 73 + 1 + 1 + 1 + 139;
73         const WEIGHT_RECEIVED_HTLC_ANCHORS: u64 = WEIGHT_RECEIVED_HTLC + 3; // + OP_1 + OP_CSV + OP_DROP
74         if opt_anchors { WEIGHT_RECEIVED_HTLC_ANCHORS } else { WEIGHT_RECEIVED_HTLC }
75 }
76
77 // number_of_witness_elements + sig_length + revocation_sig + true_length + op_true + witness_script_length + witness_script
78 pub(crate) const WEIGHT_REVOKED_OUTPUT: u64 = 1 + 1 + 73 + 1 + 1 + 1 + 77;
79
80 /// Height delay at which transactions are fee-bumped/rebroadcasted with a low priority.
81 const LOW_FREQUENCY_BUMP_INTERVAL: u32 = 15;
82 /// Height delay at which transactions are fee-bumped/rebroadcasted with a middle priority.
83 const MIDDLE_FREQUENCY_BUMP_INTERVAL: u32 = 3;
84 /// Height delay at which transactions are fee-bumped/rebroadcasted with a high priority.
85 const HIGH_FREQUENCY_BUMP_INTERVAL: u32 = 1;
86
87 /// A struct to describe a revoked output and corresponding information to generate a solving
88 /// witness spending a commitment `to_local` output or a second-stage HTLC transaction output.
89 ///
90 /// CSV and pubkeys are used as part of a witnessScript redeeming a balance output, amount is used
91 /// as part of the signature hash and revocation secret to generate a satisfying witness.
92 #[derive(Clone, PartialEq, Eq)]
93 pub(crate) struct RevokedOutput {
94         per_commitment_point: PublicKey,
95         counterparty_delayed_payment_base_key: PublicKey,
96         counterparty_htlc_base_key: PublicKey,
97         per_commitment_key: SecretKey,
98         weight: u64,
99         amount: u64,
100         on_counterparty_tx_csv: u16,
101 }
102
103 impl RevokedOutput {
104         pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: PublicKey, counterparty_htlc_base_key: PublicKey, per_commitment_key: SecretKey, amount: u64, on_counterparty_tx_csv: u16) -> Self {
105                 RevokedOutput {
106                         per_commitment_point,
107                         counterparty_delayed_payment_base_key,
108                         counterparty_htlc_base_key,
109                         per_commitment_key,
110                         weight: WEIGHT_REVOKED_OUTPUT,
111                         amount,
112                         on_counterparty_tx_csv
113                 }
114         }
115 }
116
117 impl_writeable_tlv_based!(RevokedOutput, {
118         (0, per_commitment_point, required),
119         (2, counterparty_delayed_payment_base_key, required),
120         (4, counterparty_htlc_base_key, required),
121         (6, per_commitment_key, required),
122         (8, weight, required),
123         (10, amount, required),
124         (12, on_counterparty_tx_csv, required),
125 });
126
127 /// A struct to describe a revoked offered output and corresponding information to generate a
128 /// solving witness.
129 ///
130 /// HTLCOuputInCommitment (hash timelock, direction) and pubkeys are used to generate a suitable
131 /// witnessScript.
132 ///
133 /// CSV is used as part of a witnessScript redeeming a balance output, amount is used as part
134 /// of the signature hash and revocation secret to generate a satisfying witness.
135 #[derive(Clone, PartialEq, Eq)]
136 pub(crate) struct RevokedHTLCOutput {
137         per_commitment_point: PublicKey,
138         counterparty_delayed_payment_base_key: PublicKey,
139         counterparty_htlc_base_key: PublicKey,
140         per_commitment_key: SecretKey,
141         weight: u64,
142         amount: u64,
143         htlc: HTLCOutputInCommitment,
144 }
145
146 impl RevokedHTLCOutput {
147         pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: PublicKey, counterparty_htlc_base_key: PublicKey, per_commitment_key: SecretKey, amount: u64, htlc: HTLCOutputInCommitment, opt_anchors: bool) -> Self {
148                 let weight = if htlc.offered { weight_revoked_offered_htlc(opt_anchors) } else { weight_revoked_received_htlc(opt_anchors) };
149                 RevokedHTLCOutput {
150                         per_commitment_point,
151                         counterparty_delayed_payment_base_key,
152                         counterparty_htlc_base_key,
153                         per_commitment_key,
154                         weight,
155                         amount,
156                         htlc
157                 }
158         }
159 }
160
161 impl_writeable_tlv_based!(RevokedHTLCOutput, {
162         (0, per_commitment_point, required),
163         (2, counterparty_delayed_payment_base_key, required),
164         (4, counterparty_htlc_base_key, required),
165         (6, per_commitment_key, required),
166         (8, weight, required),
167         (10, amount, required),
168         (12, htlc, required),
169 });
170
171 /// A struct to describe a HTLC output on a counterparty commitment transaction.
172 ///
173 /// HTLCOutputInCommitment (hash, timelock, directon) and pubkeys are used to generate a suitable
174 /// witnessScript.
175 ///
176 /// The preimage is used as part of the witness.
177 #[derive(Clone, PartialEq, Eq)]
178 pub(crate) struct CounterpartyOfferedHTLCOutput {
179         per_commitment_point: PublicKey,
180         counterparty_delayed_payment_base_key: PublicKey,
181         counterparty_htlc_base_key: PublicKey,
182         preimage: PaymentPreimage,
183         htlc: HTLCOutputInCommitment,
184         opt_anchors: Option<()>,
185 }
186
187 impl CounterpartyOfferedHTLCOutput {
188         pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: PublicKey, counterparty_htlc_base_key: PublicKey, preimage: PaymentPreimage, htlc: HTLCOutputInCommitment, opt_anchors: bool) -> Self {
189                 CounterpartyOfferedHTLCOutput {
190                         per_commitment_point,
191                         counterparty_delayed_payment_base_key,
192                         counterparty_htlc_base_key,
193                         preimage,
194                         htlc,
195                         opt_anchors: if opt_anchors { Some(()) } else { None },
196                 }
197         }
198
199         fn opt_anchors(&self) -> bool {
200                 self.opt_anchors.is_some()
201         }
202 }
203
204 impl_writeable_tlv_based!(CounterpartyOfferedHTLCOutput, {
205         (0, per_commitment_point, required),
206         (2, counterparty_delayed_payment_base_key, required),
207         (4, counterparty_htlc_base_key, required),
208         (6, preimage, required),
209         (8, htlc, required),
210         (10, opt_anchors, option),
211 });
212
213 /// A struct to describe a HTLC output on a counterparty commitment transaction.
214 ///
215 /// HTLCOutputInCommitment (hash, timelock, directon) and pubkeys are used to generate a suitable
216 /// witnessScript.
217 #[derive(Clone, PartialEq, Eq)]
218 pub(crate) struct CounterpartyReceivedHTLCOutput {
219         per_commitment_point: PublicKey,
220         counterparty_delayed_payment_base_key: PublicKey,
221         counterparty_htlc_base_key: PublicKey,
222         htlc: HTLCOutputInCommitment,
223         opt_anchors: Option<()>,
224 }
225
226 impl CounterpartyReceivedHTLCOutput {
227         pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: PublicKey, counterparty_htlc_base_key: PublicKey, htlc: HTLCOutputInCommitment, opt_anchors: bool) -> Self {
228                 CounterpartyReceivedHTLCOutput {
229                         per_commitment_point,
230                         counterparty_delayed_payment_base_key,
231                         counterparty_htlc_base_key,
232                         htlc,
233                         opt_anchors: if opt_anchors { Some(()) } else { None },
234                 }
235         }
236
237         fn opt_anchors(&self) -> bool {
238                 self.opt_anchors.is_some()
239         }
240 }
241
242 impl_writeable_tlv_based!(CounterpartyReceivedHTLCOutput, {
243         (0, per_commitment_point, required),
244         (2, counterparty_delayed_payment_base_key, required),
245         (4, counterparty_htlc_base_key, required),
246         (6, htlc, required),
247         (8, opt_anchors, option),
248 });
249
250 /// A struct to describe a HTLC output on holder commitment transaction.
251 ///
252 /// Either offered or received, the amount is always used as part of the bip143 sighash.
253 /// Preimage is only included as part of the witness in former case.
254 #[derive(Clone, PartialEq, Eq)]
255 pub(crate) struct HolderHTLCOutput {
256         preimage: Option<PaymentPreimage>,
257         amount_msat: u64,
258         /// Defaults to 0 for HTLC-Success transactions, which have no expiry
259         cltv_expiry: u32,
260         opt_anchors: Option<()>,
261 }
262
263 impl HolderHTLCOutput {
264         pub(crate) fn build_offered(amount_msat: u64, cltv_expiry: u32, opt_anchors: bool) -> Self {
265                 HolderHTLCOutput {
266                         preimage: None,
267                         amount_msat,
268                         cltv_expiry,
269                         opt_anchors: if opt_anchors { Some(()) } else { None } ,
270                 }
271         }
272
273         pub(crate) fn build_accepted(preimage: PaymentPreimage, amount_msat: u64, opt_anchors: bool) -> Self {
274                 HolderHTLCOutput {
275                         preimage: Some(preimage),
276                         amount_msat,
277                         cltv_expiry: 0,
278                         opt_anchors: if opt_anchors { Some(()) } else { None } ,
279                 }
280         }
281
282         fn opt_anchors(&self) -> bool {
283                 self.opt_anchors.is_some()
284         }
285 }
286
287 impl_writeable_tlv_based!(HolderHTLCOutput, {
288         (0, amount_msat, required),
289         (2, cltv_expiry, required),
290         (4, preimage, option),
291         (6, opt_anchors, option)
292 });
293
294 /// A struct to describe the channel output on the funding transaction.
295 ///
296 /// witnessScript is used as part of the witness redeeming the funding utxo.
297 #[derive(Clone, PartialEq, Eq)]
298 pub(crate) struct HolderFundingOutput {
299         funding_redeemscript: Script,
300         funding_amount: Option<u64>,
301         opt_anchors: Option<()>,
302 }
303
304
305 impl HolderFundingOutput {
306         pub(crate) fn build(funding_redeemscript: Script, funding_amount: u64, opt_anchors: bool) -> Self {
307                 HolderFundingOutput {
308                         funding_redeemscript,
309                         funding_amount: Some(funding_amount),
310                         opt_anchors: if opt_anchors { Some(()) } else { None },
311                 }
312         }
313
314         fn opt_anchors(&self) -> bool {
315                 self.opt_anchors.is_some()
316         }
317 }
318
319 impl_writeable_tlv_based!(HolderFundingOutput, {
320         (0, funding_redeemscript, required),
321         (2, opt_anchors, option),
322         (3, funding_amount, option),
323 });
324
325 /// A wrapper encapsulating all in-protocol differing outputs types.
326 ///
327 /// The generic API offers access to an outputs common attributes or allow transformation such as
328 /// finalizing an input claiming the output.
329 #[derive(Clone, PartialEq, Eq)]
330 pub(crate) enum PackageSolvingData {
331         RevokedOutput(RevokedOutput),
332         RevokedHTLCOutput(RevokedHTLCOutput),
333         CounterpartyOfferedHTLCOutput(CounterpartyOfferedHTLCOutput),
334         CounterpartyReceivedHTLCOutput(CounterpartyReceivedHTLCOutput),
335         HolderHTLCOutput(HolderHTLCOutput),
336         HolderFundingOutput(HolderFundingOutput),
337 }
338
339 impl PackageSolvingData {
340         fn amount(&self) -> u64 {
341                 let amt = match self {
342                         PackageSolvingData::RevokedOutput(ref outp) => outp.amount,
343                         PackageSolvingData::RevokedHTLCOutput(ref outp) => outp.amount,
344                         PackageSolvingData::CounterpartyOfferedHTLCOutput(ref outp) => outp.htlc.amount_msat / 1000,
345                         PackageSolvingData::CounterpartyReceivedHTLCOutput(ref outp) => outp.htlc.amount_msat / 1000,
346                         PackageSolvingData::HolderHTLCOutput(ref outp) => {
347                                 debug_assert!(outp.opt_anchors());
348                                 outp.amount_msat / 1000
349                         },
350                         PackageSolvingData::HolderFundingOutput(ref outp) => {
351                                 debug_assert!(outp.opt_anchors());
352                                 outp.funding_amount.unwrap()
353                         }
354                 };
355                 amt
356         }
357         fn weight(&self) -> usize {
358                 match self {
359                         PackageSolvingData::RevokedOutput(ref outp) => outp.weight as usize,
360                         PackageSolvingData::RevokedHTLCOutput(ref outp) => outp.weight as usize,
361                         PackageSolvingData::CounterpartyOfferedHTLCOutput(ref outp) => weight_offered_htlc(outp.opt_anchors()) as usize,
362                         PackageSolvingData::CounterpartyReceivedHTLCOutput(ref outp) => weight_received_htlc(outp.opt_anchors()) as usize,
363                         PackageSolvingData::HolderHTLCOutput(ref outp) => {
364                                 debug_assert!(outp.opt_anchors());
365                                 if outp.preimage.is_none() {
366                                         weight_offered_htlc(true) as usize
367                                 } else {
368                                         weight_received_htlc(true) as usize
369                                 }
370                         },
371                         // Since HolderFundingOutput maps to an untractable package that is already signed, its
372                         // weight can be determined from the transaction itself.
373                         PackageSolvingData::HolderFundingOutput(..) => unreachable!(),
374                 }
375         }
376         fn is_compatible(&self, input: &PackageSolvingData) -> bool {
377                 match self {
378                         PackageSolvingData::RevokedOutput(..) => {
379                                 match input {
380                                         PackageSolvingData::RevokedHTLCOutput(..) => { true },
381                                         PackageSolvingData::RevokedOutput(..) => { true },
382                                         _ => { false }
383                                 }
384                         },
385                         PackageSolvingData::RevokedHTLCOutput(..) => {
386                                 match input {
387                                         PackageSolvingData::RevokedOutput(..) => { true },
388                                         PackageSolvingData::RevokedHTLCOutput(..) => { true },
389                                         _ => { false }
390                                 }
391                         },
392                         _ => { mem::discriminant(self) == mem::discriminant(&input) }
393                 }
394         }
395         fn finalize_input<Signer: WriteableEcdsaChannelSigner>(&self, bumped_tx: &mut Transaction, i: usize, onchain_handler: &mut OnchainTxHandler<Signer>) -> bool {
396                 match self {
397                         PackageSolvingData::RevokedOutput(ref outp) => {
398                                 let chan_keys = TxCreationKeys::derive_new(&onchain_handler.secp_ctx, &outp.per_commitment_point, &outp.counterparty_delayed_payment_base_key, &outp.counterparty_htlc_base_key, &onchain_handler.signer.pubkeys().revocation_basepoint, &onchain_handler.signer.pubkeys().htlc_basepoint);
399                                 let witness_script = chan_utils::get_revokeable_redeemscript(&chan_keys.revocation_key, outp.on_counterparty_tx_csv, &chan_keys.broadcaster_delayed_payment_key);
400                                 //TODO: should we panic on signer failure ?
401                                 if let Ok(sig) = onchain_handler.signer.sign_justice_revoked_output(&bumped_tx, i, outp.amount, &outp.per_commitment_key, &onchain_handler.secp_ctx) {
402                                         let mut ser_sig = sig.serialize_der().to_vec();
403                                         ser_sig.push(EcdsaSighashType::All as u8);
404                                         bumped_tx.input[i].witness.push(ser_sig);
405                                         bumped_tx.input[i].witness.push(vec!(1));
406                                         bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
407                                 } else { return false; }
408                         },
409                         PackageSolvingData::RevokedHTLCOutput(ref outp) => {
410                                 let chan_keys = TxCreationKeys::derive_new(&onchain_handler.secp_ctx, &outp.per_commitment_point, &outp.counterparty_delayed_payment_base_key, &outp.counterparty_htlc_base_key, &onchain_handler.signer.pubkeys().revocation_basepoint, &onchain_handler.signer.pubkeys().htlc_basepoint);
411                                 let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&outp.htlc, onchain_handler.opt_anchors(), &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);
412                                 //TODO: should we panic on signer failure ?
413                                 if let Ok(sig) = onchain_handler.signer.sign_justice_revoked_htlc(&bumped_tx, i, outp.amount, &outp.per_commitment_key, &outp.htlc, &onchain_handler.secp_ctx) {
414                                         let mut ser_sig = sig.serialize_der().to_vec();
415                                         ser_sig.push(EcdsaSighashType::All as u8);
416                                         bumped_tx.input[i].witness.push(ser_sig);
417                                         bumped_tx.input[i].witness.push(chan_keys.revocation_key.clone().serialize().to_vec());
418                                         bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
419                                 } else { return false; }
420                         },
421                         PackageSolvingData::CounterpartyOfferedHTLCOutput(ref outp) => {
422                                 let chan_keys = TxCreationKeys::derive_new(&onchain_handler.secp_ctx, &outp.per_commitment_point, &outp.counterparty_delayed_payment_base_key, &outp.counterparty_htlc_base_key, &onchain_handler.signer.pubkeys().revocation_basepoint, &onchain_handler.signer.pubkeys().htlc_basepoint);
423                                 let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&outp.htlc, onchain_handler.opt_anchors(), &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);
424
425                                 if let Ok(sig) = onchain_handler.signer.sign_counterparty_htlc_transaction(&bumped_tx, i, &outp.htlc.amount_msat / 1000, &outp.per_commitment_point, &outp.htlc, &onchain_handler.secp_ctx) {
426                                         let mut ser_sig = sig.serialize_der().to_vec();
427                                         ser_sig.push(EcdsaSighashType::All as u8);
428                                         bumped_tx.input[i].witness.push(ser_sig);
429                                         bumped_tx.input[i].witness.push(outp.preimage.0.to_vec());
430                                         bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
431                                 }
432                         },
433                         PackageSolvingData::CounterpartyReceivedHTLCOutput(ref outp) => {
434                                 let chan_keys = TxCreationKeys::derive_new(&onchain_handler.secp_ctx, &outp.per_commitment_point, &outp.counterparty_delayed_payment_base_key, &outp.counterparty_htlc_base_key, &onchain_handler.signer.pubkeys().revocation_basepoint, &onchain_handler.signer.pubkeys().htlc_basepoint);
435                                 let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&outp.htlc, onchain_handler.opt_anchors(), &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);
436
437                                 if let Ok(sig) = onchain_handler.signer.sign_counterparty_htlc_transaction(&bumped_tx, i, &outp.htlc.amount_msat / 1000, &outp.per_commitment_point, &outp.htlc, &onchain_handler.secp_ctx) {
438                                         let mut ser_sig = sig.serialize_der().to_vec();
439                                         ser_sig.push(EcdsaSighashType::All as u8);
440                                         bumped_tx.input[i].witness.push(ser_sig);
441                                         // Due to BIP146 (MINIMALIF) this must be a zero-length element to relay.
442                                         bumped_tx.input[i].witness.push(vec![]);
443                                         bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
444                                 }
445                         },
446                         _ => { panic!("API Error!"); }
447                 }
448                 true
449         }
450         fn get_finalized_tx<Signer: WriteableEcdsaChannelSigner>(&self, outpoint: &BitcoinOutPoint, onchain_handler: &mut OnchainTxHandler<Signer>) -> Option<Transaction> {
451                 match self {
452                         PackageSolvingData::HolderHTLCOutput(ref outp) => {
453                                 debug_assert!(!outp.opt_anchors());
454                                 return onchain_handler.get_fully_signed_htlc_tx(outpoint, &outp.preimage);
455                         }
456                         PackageSolvingData::HolderFundingOutput(ref outp) => {
457                                 return Some(onchain_handler.get_fully_signed_holder_tx(&outp.funding_redeemscript));
458                         }
459                         _ => { panic!("API Error!"); }
460                 }
461         }
462         fn absolute_tx_timelock(&self, current_height: u32) -> u32 {
463                 // We use `current_height + 1` as our default locktime to discourage fee sniping and because
464                 // transactions with it always propagate.
465                 let absolute_timelock = match self {
466                         PackageSolvingData::RevokedOutput(_) => current_height + 1,
467                         PackageSolvingData::RevokedHTLCOutput(_) => current_height + 1,
468                         PackageSolvingData::CounterpartyOfferedHTLCOutput(_) => current_height + 1,
469                         PackageSolvingData::CounterpartyReceivedHTLCOutput(ref outp) => cmp::max(outp.htlc.cltv_expiry, current_height + 1),
470                         // HTLC timeout/success transactions rely on a fixed timelock due to the counterparty's
471                         // signature.
472                         PackageSolvingData::HolderHTLCOutput(ref outp) => {
473                                 if outp.preimage.is_some() {
474                                         debug_assert_eq!(outp.cltv_expiry, 0);
475                                 }
476                                 outp.cltv_expiry
477                         },
478                         PackageSolvingData::HolderFundingOutput(_) => current_height + 1,
479                 };
480                 absolute_timelock
481         }
482 }
483
484 impl_writeable_tlv_based_enum!(PackageSolvingData, ;
485         (0, RevokedOutput),
486         (1, RevokedHTLCOutput),
487         (2, CounterpartyOfferedHTLCOutput),
488         (3, CounterpartyReceivedHTLCOutput),
489         (4, HolderHTLCOutput),
490         (5, HolderFundingOutput),
491 );
492
493 /// A malleable package might be aggregated with other packages to save on fees.
494 /// A untractable package has been counter-signed and aggregable will break cached counterparty
495 /// signatures.
496 #[derive(Clone, PartialEq, Eq)]
497 pub(crate) enum PackageMalleability {
498         Malleable,
499         Untractable,
500 }
501
502 /// A structure to describe a package content that is generated by ChannelMonitor and
503 /// used by OnchainTxHandler to generate and broadcast transactions settling onchain claims.
504 ///
505 /// A package is defined as one or more transactions claiming onchain outputs in reaction
506 /// to confirmation of a channel transaction. Those packages might be aggregated to save on
507 /// fees, if satisfaction of outputs's witnessScript let's us do so.
508 ///
509 /// As packages are time-sensitive, we fee-bump and rebroadcast them at scheduled intervals.
510 /// Failing to confirm a package translate as a loss of funds for the user.
511 #[derive(Clone, PartialEq, Eq)]
512 pub struct PackageTemplate {
513         // List of onchain outputs and solving data to generate satisfying witnesses.
514         inputs: Vec<(BitcoinOutPoint, PackageSolvingData)>,
515         // Packages are deemed as malleable if we have local knwoledge of at least one set of
516         // private keys yielding a satisfying witnesses. Malleability implies that we can aggregate
517         // packages among them to save on fees or rely on RBF to bump their feerates.
518         // Untractable packages have been counter-signed and thus imply that we can't aggregate
519         // them without breaking signatures. Fee-bumping strategy will also rely on CPFP.
520         malleability: PackageMalleability,
521         // Block height after which the earlier-output belonging to this package is mature for a
522         // competing claim by the counterparty. As our chain tip becomes nearer from the timelock,
523         // the fee-bumping frequency will increase. See `OnchainTxHandler::get_height_timer`.
524         soonest_conf_deadline: u32,
525         // Determines if this package can be aggregated.
526         // Timelocked outputs belonging to the same transaction might have differing
527         // satisfying heights. Picking up the later height among the output set would be a valid
528         // aggregable strategy but it comes with at least 2 trade-offs :
529         // * earlier-output fund are going to take longer to come back
530         // * CLTV delta backing up a corresponding HTLC on an upstream channel could be swallowed
531         // by the requirement of the later-output part of the set
532         // For now, we mark such timelocked outputs as non-aggregable, though we might introduce
533         // smarter aggregable strategy in the future.
534         aggregable: bool,
535         // Cache of package feerate committed at previous (re)broadcast. If bumping resources
536         // (either claimed output value or external utxo), it will keep increasing until holder
537         // or counterparty successful claim.
538         feerate_previous: u64,
539         // Cache of next height at which fee-bumping and rebroadcast will be attempted. In
540         // the future, we might abstract it to an observed mempool fluctuation.
541         height_timer: u32,
542         // Confirmation height of the claimed outputs set transaction. In case of reorg reaching
543         // it, we wipe out and forget the package.
544         height_original: u32,
545 }
546
547 impl PackageTemplate {
548         pub(crate) fn is_malleable(&self) -> bool {
549                 self.malleability == PackageMalleability::Malleable
550         }
551         pub(crate) fn timelock(&self) -> u32 {
552                 self.soonest_conf_deadline
553         }
554         pub(crate) fn aggregable(&self) -> bool {
555                 self.aggregable
556         }
557         pub(crate) fn previous_feerate(&self) -> u64 {
558                 self.feerate_previous
559         }
560         pub(crate) fn set_feerate(&mut self, new_feerate: u64) {
561                 self.feerate_previous = new_feerate;
562         }
563         pub(crate) fn timer(&self) -> u32 {
564                 self.height_timer
565         }
566         pub(crate) fn set_timer(&mut self, new_timer: u32) {
567                 self.height_timer = new_timer;
568         }
569         pub(crate) fn outpoints(&self) -> Vec<&BitcoinOutPoint> {
570                 self.inputs.iter().map(|(o, _)| o).collect()
571         }
572         pub(crate) fn inputs(&self) -> impl ExactSizeIterator<Item = &PackageSolvingData> {
573                 self.inputs.iter().map(|(_, i)| i)
574         }
575         pub(crate) fn split_package(&mut self, split_outp: &BitcoinOutPoint) -> Option<PackageTemplate> {
576                 match self.malleability {
577                         PackageMalleability::Malleable => {
578                                 let mut split_package = None;
579                                 let timelock = self.soonest_conf_deadline;
580                                 let aggregable = self.aggregable;
581                                 let feerate_previous = self.feerate_previous;
582                                 let height_timer = self.height_timer;
583                                 let height_original = self.height_original;
584                                 self.inputs.retain(|outp| {
585                                         if *split_outp == outp.0 {
586                                                 split_package = Some(PackageTemplate {
587                                                         inputs: vec![(outp.0, outp.1.clone())],
588                                                         malleability: PackageMalleability::Malleable,
589                                                         soonest_conf_deadline: timelock,
590                                                         aggregable,
591                                                         feerate_previous,
592                                                         height_timer,
593                                                         height_original,
594                                                 });
595                                                 return false;
596                                         }
597                                         return true;
598                                 });
599                                 return split_package;
600                         },
601                         _ => {
602                                 // Note, we may try to split on remote transaction for
603                                 // which we don't have a competing one (HTLC-Success before
604                                 // timelock expiration). This explain we don't panic!
605                                 // We should refactor OnchainTxHandler::block_connected to
606                                 // only test equality on competing claims.
607                                 return None;
608                         }
609                 }
610         }
611         pub(crate) fn merge_package(&mut self, mut merge_from: PackageTemplate) {
612                 assert_eq!(self.height_original, merge_from.height_original);
613                 if self.malleability == PackageMalleability::Untractable || merge_from.malleability == PackageMalleability::Untractable {
614                         panic!("Merging template on untractable packages");
615                 }
616                 if !self.aggregable || !merge_from.aggregable {
617                         panic!("Merging non aggregatable packages");
618                 }
619                 if let Some((_, lead_input)) = self.inputs.first() {
620                         for (_, v) in merge_from.inputs.iter() {
621                                 if !lead_input.is_compatible(v) { panic!("Merging outputs from differing types !"); }
622                         }
623                 } else { panic!("Merging template on an empty package"); }
624                 for (k, v) in merge_from.inputs.drain(..) {
625                         self.inputs.push((k, v));
626                 }
627                 //TODO: verify coverage and sanity?
628                 if self.soonest_conf_deadline > merge_from.soonest_conf_deadline {
629                         self.soonest_conf_deadline = merge_from.soonest_conf_deadline;
630                 }
631                 if self.feerate_previous > merge_from.feerate_previous {
632                         self.feerate_previous = merge_from.feerate_previous;
633                 }
634                 self.height_timer = cmp::min(self.height_timer, merge_from.height_timer);
635         }
636         /// Gets the amount of all outptus being spent by this package, only valid for malleable
637         /// packages.
638         pub(crate) fn package_amount(&self) -> u64 {
639                 let mut amounts = 0;
640                 for (_, outp) in self.inputs.iter() {
641                         amounts += outp.amount();
642                 }
643                 amounts
644         }
645         pub(crate) fn package_locktime(&self, current_height: u32) -> u32 {
646                 let locktime = self.inputs.iter().map(|(_, outp)| outp.absolute_tx_timelock(current_height))
647                         .max().expect("There must always be at least one output to spend in a PackageTemplate");
648
649                 // If we ever try to aggregate a `HolderHTLCOutput`s with another output type, we'll likely
650                 // end up with an incorrect transaction locktime since the counterparty has included it in
651                 // its HTLC signature. This should never happen unless we decide to aggregate outputs across
652                 // different channel commitments.
653                 #[cfg(debug_assertions)] {
654                         if self.inputs.iter().any(|(_, outp)|
655                                 if let PackageSolvingData::HolderHTLCOutput(outp) = outp {
656                                         outp.preimage.is_some()
657                                 } else {
658                                         false
659                                 }
660                         ) {
661                                 debug_assert_eq!(locktime, 0);
662                         };
663                         for timeout_htlc_expiry in self.inputs.iter().filter_map(|(_, outp)|
664                                 if let PackageSolvingData::HolderHTLCOutput(outp) = outp {
665                                         if outp.preimage.is_none() {
666                                                 Some(outp.cltv_expiry)
667                                         } else { None }
668                                 } else { None }
669                         ) {
670                                 debug_assert_eq!(locktime, timeout_htlc_expiry);
671                         }
672                 }
673
674                 locktime
675         }
676         pub(crate) fn package_weight(&self, destination_script: &Script) -> usize {
677                 let mut inputs_weight = 0;
678                 let mut witnesses_weight = 2; // count segwit flags
679                 for (_, outp) in self.inputs.iter() {
680                         // previous_out_point: 36 bytes ; var_int: 1 byte ; sequence: 4 bytes
681                         inputs_weight += 41 * WITNESS_SCALE_FACTOR;
682                         witnesses_weight += outp.weight();
683                 }
684                 // version: 4 bytes ; count_tx_in: 1 byte ; count_tx_out: 1 byte ; lock_time: 4 bytes
685                 let transaction_weight = 10 * WITNESS_SCALE_FACTOR;
686                 // value: 8 bytes ; var_int: 1 byte ; pk_script: `destination_script.len()`
687                 let output_weight = (8 + 1 + destination_script.len()) * WITNESS_SCALE_FACTOR;
688                 inputs_weight + witnesses_weight + transaction_weight + output_weight
689         }
690         #[cfg(anchors)]
691         pub(crate) fn construct_malleable_package_with_external_funding<Signer: WriteableEcdsaChannelSigner>(
692                 &self, onchain_handler: &mut OnchainTxHandler<Signer>,
693         ) -> Option<Vec<ExternalHTLCClaim>> {
694                 debug_assert!(self.requires_external_funding());
695                 let mut htlcs: Option<Vec<ExternalHTLCClaim>> = None;
696                 for (previous_output, input) in &self.inputs {
697                         match input {
698                                 PackageSolvingData::HolderHTLCOutput(ref outp) => {
699                                         debug_assert!(outp.opt_anchors());
700                                         onchain_handler.generate_external_htlc_claim(&previous_output, &outp.preimage).map(|htlc| {
701                                                 htlcs.get_or_insert_with(|| Vec::with_capacity(self.inputs.len())).push(htlc);
702                                         });
703                                 }
704                                 _ => debug_assert!(false, "Expected HolderHTLCOutputs to not be aggregated with other input types"),
705                         }
706                 }
707                 htlcs
708         }
709         pub(crate) fn finalize_malleable_package<L: Deref, Signer: WriteableEcdsaChannelSigner>(
710                 &self, current_height: u32, onchain_handler: &mut OnchainTxHandler<Signer>, value: u64,
711                 destination_script: Script, logger: &L
712         ) -> Option<Transaction> where L::Target: Logger {
713                 debug_assert!(self.is_malleable());
714                 let mut bumped_tx = Transaction {
715                         version: 2,
716                         lock_time: PackedLockTime(self.package_locktime(current_height)),
717                         input: vec![],
718                         output: vec![TxOut {
719                                 script_pubkey: destination_script,
720                                 value,
721                         }],
722                 };
723                 for (outpoint, _) in self.inputs.iter() {
724                         bumped_tx.input.push(TxIn {
725                                 previous_output: *outpoint,
726                                 script_sig: Script::new(),
727                                 sequence: Sequence::ENABLE_RBF_NO_LOCKTIME,
728                                 witness: Witness::new(),
729                         });
730                 }
731                 for (i, (outpoint, out)) in self.inputs.iter().enumerate() {
732                         log_debug!(logger, "Adding claiming input for outpoint {}:{}", outpoint.txid, outpoint.vout);
733                         if !out.finalize_input(&mut bumped_tx, i, onchain_handler) { return None; }
734                 }
735                 log_debug!(logger, "Finalized transaction {} ready to broadcast", bumped_tx.txid());
736                 Some(bumped_tx)
737         }
738         pub(crate) fn finalize_untractable_package<L: Deref, Signer: WriteableEcdsaChannelSigner>(
739                 &self, onchain_handler: &mut OnchainTxHandler<Signer>, logger: &L,
740         ) -> Option<Transaction> where L::Target: Logger {
741                 debug_assert!(!self.is_malleable());
742                 if let Some((outpoint, outp)) = self.inputs.first() {
743                         if let Some(final_tx) = outp.get_finalized_tx(outpoint, onchain_handler) {
744                                 log_debug!(logger, "Adding claiming input for outpoint {}:{}", outpoint.txid, outpoint.vout);
745                                 log_debug!(logger, "Finalized transaction {} ready to broadcast", final_tx.txid());
746                                 return Some(final_tx);
747                         }
748                         return None;
749                 } else { panic!("API Error: Package must not be inputs empty"); }
750         }
751         /// In LN, output claimed are time-sensitive, which means we have to spend them before reaching some timelock expiration. At in-channel
752         /// output detection, we generate a first version of a claim tx and associate to it a height timer. A height timer is an absolute block
753         /// height that once reached we should generate a new bumped "version" of the claim tx to be sure that we safely claim outputs before
754         /// that our counterparty can do so. If timelock expires soon, height timer is going to be scaled down in consequence to increase
755         /// frequency of the bump and so increase our bets of success.
756         pub(crate) fn get_height_timer(&self, current_height: u32) -> u32 {
757                 if self.soonest_conf_deadline <= current_height + MIDDLE_FREQUENCY_BUMP_INTERVAL {
758                         return current_height + HIGH_FREQUENCY_BUMP_INTERVAL
759                 } else if self.soonest_conf_deadline - current_height <= LOW_FREQUENCY_BUMP_INTERVAL {
760                         return current_height + MIDDLE_FREQUENCY_BUMP_INTERVAL
761                 }
762                 current_height + LOW_FREQUENCY_BUMP_INTERVAL
763         }
764
765         /// Returns value in satoshis to be included as package outgoing output amount and feerate
766         /// which was used to generate the value. Will not return less than `dust_limit_sats` for the
767         /// value.
768         pub(crate) fn compute_package_output<F: Deref, L: Deref>(
769                 &self, predicted_weight: usize, dust_limit_sats: u64, force_feerate_bump: bool,
770                 fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L,
771         ) -> Option<(u64, u64)>
772         where
773                 F::Target: FeeEstimator,
774                 L::Target: Logger,
775         {
776                 debug_assert!(self.malleability == PackageMalleability::Malleable, "The package output is fixed for non-malleable packages");
777                 let input_amounts = self.package_amount();
778                 assert!(dust_limit_sats as i64 > 0, "Output script must be broadcastable/have a 'real' dust limit.");
779                 // If old feerate is 0, first iteration of this claim, use normal fee calculation
780                 if self.feerate_previous != 0 {
781                         if let Some((new_fee, feerate)) = feerate_bump(
782                                 predicted_weight, input_amounts, self.feerate_previous, force_feerate_bump,
783                                 fee_estimator, logger,
784                         ) {
785                                 return Some((cmp::max(input_amounts as i64 - new_fee as i64, dust_limit_sats as i64) as u64, feerate));
786                         }
787                 } else {
788                         if let Some((new_fee, feerate)) = compute_fee_from_spent_amounts(input_amounts, predicted_weight, fee_estimator, logger) {
789                                 return Some((cmp::max(input_amounts as i64 - new_fee as i64, dust_limit_sats as i64) as u64, feerate));
790                         }
791                 }
792                 None
793         }
794
795         #[cfg(anchors)]
796         /// Computes a feerate based on the given confirmation target. If a previous feerate was used,
797         /// the new feerate is below it, and `force_feerate_bump` is set, we'll use a 25% increase of
798         /// the previous feerate instead of the new feerate.
799         pub(crate) fn compute_package_feerate<F: Deref>(
800                 &self, fee_estimator: &LowerBoundedFeeEstimator<F>, conf_target: ConfirmationTarget,
801                 force_feerate_bump: bool,
802         ) -> u32 where F::Target: FeeEstimator {
803                 let feerate_estimate = fee_estimator.bounded_sat_per_1000_weight(conf_target);
804                 if self.feerate_previous != 0 {
805                         // If old feerate inferior to actual one given back by Fee Estimator, use it to compute new fee...
806                         if feerate_estimate as u64 > self.feerate_previous {
807                                 feerate_estimate
808                         } else if !force_feerate_bump {
809                                 self.feerate_previous.try_into().unwrap_or(u32::max_value())
810                         } else {
811                                 // ...else just increase the previous feerate by 25% (because that's a nice number)
812                                 (self.feerate_previous + (self.feerate_previous / 4)).try_into().unwrap_or(u32::max_value())
813                         }
814                 } else {
815                         feerate_estimate
816                 }
817         }
818
819         /// Determines whether a package contains an input which must have additional external inputs
820         /// attached to help the spending transaction reach confirmation.
821         pub(crate) fn requires_external_funding(&self) -> bool {
822                 self.inputs.iter().find(|input| match input.1 {
823                         PackageSolvingData::HolderFundingOutput(ref outp) => outp.opt_anchors(),
824                         PackageSolvingData::HolderHTLCOutput(ref outp) => outp.opt_anchors(),
825                         _ => false,
826                 }).is_some()
827         }
828
829         pub (crate) fn build_package(txid: Txid, vout: u32, input_solving_data: PackageSolvingData, soonest_conf_deadline: u32, aggregable: bool, height_original: u32) -> Self {
830                 let malleability = match input_solving_data {
831                         PackageSolvingData::RevokedOutput(..) => PackageMalleability::Malleable,
832                         PackageSolvingData::RevokedHTLCOutput(..) => PackageMalleability::Malleable,
833                         PackageSolvingData::CounterpartyOfferedHTLCOutput(..) => PackageMalleability::Malleable,
834                         PackageSolvingData::CounterpartyReceivedHTLCOutput(..) => PackageMalleability::Malleable,
835                         PackageSolvingData::HolderHTLCOutput(ref outp) => if outp.opt_anchors() {
836                                 PackageMalleability::Malleable
837                         } else {
838                                 PackageMalleability::Untractable
839                         },
840                         PackageSolvingData::HolderFundingOutput(..) => PackageMalleability::Untractable,
841                 };
842                 let mut inputs = Vec::with_capacity(1);
843                 inputs.push((BitcoinOutPoint { txid, vout }, input_solving_data));
844                 PackageTemplate {
845                         inputs,
846                         malleability,
847                         soonest_conf_deadline,
848                         aggregable,
849                         feerate_previous: 0,
850                         height_timer: height_original,
851                         height_original,
852                 }
853         }
854 }
855
856 impl Writeable for PackageTemplate {
857         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
858                 writer.write_all(&(self.inputs.len() as u64).to_be_bytes())?;
859                 for (ref outpoint, ref rev_outp) in self.inputs.iter() {
860                         outpoint.write(writer)?;
861                         rev_outp.write(writer)?;
862                 }
863                 write_tlv_fields!(writer, {
864                         (0, self.soonest_conf_deadline, required),
865                         (2, self.feerate_previous, required),
866                         (4, self.height_original, required),
867                         (6, self.height_timer, required)
868                 });
869                 Ok(())
870         }
871 }
872
873 impl Readable for PackageTemplate {
874         fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
875                 let inputs_count = <u64 as Readable>::read(reader)?;
876                 let mut inputs: Vec<(BitcoinOutPoint, PackageSolvingData)> = Vec::with_capacity(cmp::min(inputs_count as usize, MAX_ALLOC_SIZE / 128));
877                 for _ in 0..inputs_count {
878                         let outpoint = Readable::read(reader)?;
879                         let rev_outp = Readable::read(reader)?;
880                         inputs.push((outpoint, rev_outp));
881                 }
882                 let (malleability, aggregable) = if let Some((_, lead_input)) = inputs.first() {
883                         match lead_input {
884                                 PackageSolvingData::RevokedOutput(..) => { (PackageMalleability::Malleable, true) },
885                                 PackageSolvingData::RevokedHTLCOutput(..) => { (PackageMalleability::Malleable, true) },
886                                 PackageSolvingData::CounterpartyOfferedHTLCOutput(..) => { (PackageMalleability::Malleable, true) },
887                                 PackageSolvingData::CounterpartyReceivedHTLCOutput(..) => { (PackageMalleability::Malleable, false) },
888                                 PackageSolvingData::HolderHTLCOutput(ref outp) => if outp.opt_anchors() {
889                                         (PackageMalleability::Malleable, outp.preimage.is_some())
890                                 } else {
891                                         (PackageMalleability::Untractable, false)
892                                 },
893                                 PackageSolvingData::HolderFundingOutput(..) => { (PackageMalleability::Untractable, false) },
894                         }
895                 } else { return Err(DecodeError::InvalidValue); };
896                 let mut soonest_conf_deadline = 0;
897                 let mut feerate_previous = 0;
898                 let mut height_timer = None;
899                 let mut height_original = 0;
900                 read_tlv_fields!(reader, {
901                         (0, soonest_conf_deadline, required),
902                         (2, feerate_previous, required),
903                         (4, height_original, required),
904                         (6, height_timer, option),
905                 });
906                 if height_timer.is_none() {
907                         height_timer = Some(height_original);
908                 }
909                 Ok(PackageTemplate {
910                         inputs,
911                         malleability,
912                         soonest_conf_deadline,
913                         aggregable,
914                         feerate_previous,
915                         height_timer: height_timer.unwrap(),
916                         height_original,
917                 })
918         }
919 }
920
921 /// Attempt to propose a bumping fee for a transaction from its spent output's values and predicted
922 /// weight. We start with the highest priority feerate returned by the node's fee estimator then
923 /// fall-back to lower priorities until we have enough value available to suck from.
924 ///
925 /// If the proposed fee is less than the available spent output's values, we return the proposed
926 /// fee and the corresponding updated feerate. If the proposed fee is equal or more than the
927 /// available spent output's values, we return nothing
928 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)>
929         where F::Target: FeeEstimator,
930               L::Target: Logger,
931 {
932         let mut updated_feerate = fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::HighPriority) as u64;
933         let mut fee = updated_feerate * (predicted_weight as u64) / 1000;
934         if input_amounts <= fee {
935                 updated_feerate = fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::Normal) as u64;
936                 fee = updated_feerate * (predicted_weight as u64) / 1000;
937                 if input_amounts <= fee {
938                         updated_feerate = fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::Background) as u64;
939                         fee = updated_feerate * (predicted_weight as u64) / 1000;
940                         if input_amounts <= fee {
941                                 log_error!(logger, "Failed to generate an on-chain punishment tx as even low priority fee ({} sat) was more than the entire claim balance ({} sat)",
942                                         fee, input_amounts);
943                                 None
944                         } else {
945                                 log_warn!(logger, "Used low priority fee for on-chain punishment tx as high priority fee was more than the entire claim balance ({} sat)",
946                                         input_amounts);
947                                 Some((fee, updated_feerate))
948                         }
949                 } else {
950                         log_warn!(logger, "Used medium priority fee for on-chain punishment tx as high priority fee was more than the entire claim balance ({} sat)",
951                                 input_amounts);
952                         Some((fee, updated_feerate))
953                 }
954         } else {
955                 Some((fee, updated_feerate))
956         }
957 }
958
959 /// Attempt to propose a bumping fee for a transaction from its spent output's values and predicted
960 /// weight. If feerates proposed by the fee-estimator have been increasing since last fee-bumping
961 /// attempt, use them. If `force_feerate_bump` is set, we bump the feerate by 25% of the previous
962 /// feerate, or just use the previous feerate otherwise. If a feerate bump did happen, we also
963 /// verify that those bumping heuristics respect BIP125 rules 3) and 4) and if required adjust the
964 /// new fee to meet the RBF policy requirement.
965 fn feerate_bump<F: Deref, L: Deref>(
966         predicted_weight: usize, input_amounts: u64, previous_feerate: u64, force_feerate_bump: bool,
967         fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L,
968 ) -> Option<(u64, u64)>
969 where
970         F::Target: FeeEstimator,
971         L::Target: Logger,
972 {
973         // If old feerate inferior to actual one given back by Fee Estimator, use it to compute new fee...
974         let (new_fee, new_feerate) = if let Some((new_fee, new_feerate)) = compute_fee_from_spent_amounts(input_amounts, predicted_weight, fee_estimator, logger) {
975                 if new_feerate > previous_feerate {
976                         (new_fee, new_feerate)
977                 } else if !force_feerate_bump {
978                         let previous_fee = previous_feerate * (predicted_weight as u64) / 1000;
979                         (previous_fee, previous_feerate)
980                 } else {
981                         // ...else just increase the previous feerate by 25% (because that's a nice number)
982                         let bumped_feerate = previous_feerate + (previous_feerate / 4);
983                         let bumped_fee = bumped_feerate * (predicted_weight as u64) / 1000;
984                         if input_amounts <= bumped_fee {
985                                 log_warn!(logger, "Can't 25% bump new claiming tx, amount {} is too small", input_amounts);
986                                 return None;
987                         }
988                         (bumped_fee, bumped_feerate)
989                 }
990         } else {
991                 log_warn!(logger, "Can't new-estimation bump new claiming tx, amount {} is too small", input_amounts);
992                 return None;
993         };
994
995         // Our feerates should never decrease. If it hasn't changed though, we just need to
996         // rebroadcast/re-sign the previous claim.
997         debug_assert!(new_feerate >= previous_feerate);
998         if new_feerate == previous_feerate {
999                 return Some((new_fee, new_feerate));
1000         }
1001
1002         let previous_fee = previous_feerate * (predicted_weight as u64) / 1000;
1003         let min_relay_fee = MIN_RELAY_FEE_SAT_PER_1000_WEIGHT * (predicted_weight as u64) / 1000;
1004         // BIP 125 Opt-in Full Replace-by-Fee Signaling
1005         //      * 3. The replacement transaction pays an absolute fee of at least the sum paid by the original transactions.
1006         //      * 4. The replacement transaction must also pay for its own bandwidth at or above the rate set by the node's minimum relay fee setting.
1007         let new_fee = if new_fee < previous_fee + min_relay_fee {
1008                 new_fee + previous_fee + min_relay_fee - new_fee
1009         } else {
1010                 new_fee
1011         };
1012         Some((new_fee, new_fee * 1000 / (predicted_weight as u64)))
1013 }
1014
1015 #[cfg(test)]
1016 mod tests {
1017         use crate::chain::package::{CounterpartyOfferedHTLCOutput, CounterpartyReceivedHTLCOutput, HolderHTLCOutput, PackageTemplate, PackageSolvingData, RevokedOutput, WEIGHT_REVOKED_OUTPUT, weight_offered_htlc, weight_received_htlc};
1018         use crate::chain::Txid;
1019         use crate::ln::chan_utils::HTLCOutputInCommitment;
1020         use crate::ln::{PaymentPreimage, PaymentHash};
1021
1022         use bitcoin::blockdata::constants::WITNESS_SCALE_FACTOR;
1023         use bitcoin::blockdata::script::Script;
1024         use bitcoin::blockdata::transaction::OutPoint as BitcoinOutPoint;
1025
1026         use bitcoin::hashes::hex::FromHex;
1027
1028         use bitcoin::secp256k1::{PublicKey,SecretKey};
1029         use bitcoin::secp256k1::Secp256k1;
1030
1031         macro_rules! dumb_revk_output {
1032                 ($secp_ctx: expr) => {
1033                         {
1034                                 let dumb_scalar = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
1035                                 let dumb_point = PublicKey::from_secret_key(&$secp_ctx, &dumb_scalar);
1036                                 PackageSolvingData::RevokedOutput(RevokedOutput::build(dumb_point, dumb_point, dumb_point, dumb_scalar, 0, 0))
1037                         }
1038                 }
1039         }
1040
1041         macro_rules! dumb_counterparty_output {
1042                 ($secp_ctx: expr, $amt: expr, $opt_anchors: expr) => {
1043                         {
1044                                 let dumb_scalar = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
1045                                 let dumb_point = PublicKey::from_secret_key(&$secp_ctx, &dumb_scalar);
1046                                 let hash = PaymentHash([1; 32]);
1047                                 let htlc = HTLCOutputInCommitment { offered: true, amount_msat: $amt, cltv_expiry: 0, payment_hash: hash, transaction_output_index: None };
1048                                 PackageSolvingData::CounterpartyReceivedHTLCOutput(CounterpartyReceivedHTLCOutput::build(dumb_point, dumb_point, dumb_point, htlc, $opt_anchors))
1049                         }
1050                 }
1051         }
1052
1053         macro_rules! dumb_counterparty_offered_output {
1054                 ($secp_ctx: expr, $amt: expr, $opt_anchors: expr) => {
1055                         {
1056                                 let dumb_scalar = SecretKey::from_slice(&hex::decode("0101010101010101010101010101010101010101010101010101010101010101").unwrap()[..]).unwrap();
1057                                 let dumb_point = PublicKey::from_secret_key(&$secp_ctx, &dumb_scalar);
1058                                 let hash = PaymentHash([1; 32]);
1059                                 let preimage = PaymentPreimage([2;32]);
1060                                 let htlc = HTLCOutputInCommitment { offered: false, amount_msat: $amt, cltv_expiry: 1000, payment_hash: hash, transaction_output_index: None };
1061                                 PackageSolvingData::CounterpartyOfferedHTLCOutput(CounterpartyOfferedHTLCOutput::build(dumb_point, dumb_point, dumb_point, preimage, htlc, $opt_anchors))
1062                         }
1063                 }
1064         }
1065
1066         macro_rules! dumb_htlc_output {
1067                 () => {
1068                         {
1069                                 let preimage = PaymentPreimage([2;32]);
1070                                 PackageSolvingData::HolderHTLCOutput(HolderHTLCOutput::build_accepted(preimage, 0, false))
1071                         }
1072                 }
1073         }
1074
1075         #[test]
1076         #[should_panic]
1077         fn test_package_differing_heights() {
1078                 let txid = Txid::from_hex("c2d4449afa8d26140898dd54d3390b057ba2a5afcf03ba29d7dc0d8b9ffe966e").unwrap();
1079                 let secp_ctx = Secp256k1::new();
1080                 let revk_outp = dumb_revk_output!(secp_ctx);
1081
1082                 let mut package_one_hundred = PackageTemplate::build_package(txid, 0, revk_outp.clone(), 1000, true, 100);
1083                 let package_two_hundred = PackageTemplate::build_package(txid, 1, revk_outp.clone(), 1000, true, 200);
1084                 package_one_hundred.merge_package(package_two_hundred);
1085         }
1086
1087         #[test]
1088         #[should_panic]
1089         fn test_package_untractable_merge_to() {
1090                 let txid = Txid::from_hex("c2d4449afa8d26140898dd54d3390b057ba2a5afcf03ba29d7dc0d8b9ffe966e").unwrap();
1091                 let secp_ctx = Secp256k1::new();
1092                 let revk_outp = dumb_revk_output!(secp_ctx);
1093                 let htlc_outp = dumb_htlc_output!();
1094
1095                 let mut untractable_package = PackageTemplate::build_package(txid, 0, revk_outp.clone(), 1000, true, 100);
1096                 let malleable_package = PackageTemplate::build_package(txid, 1, htlc_outp.clone(), 1000, true, 100);
1097                 untractable_package.merge_package(malleable_package);
1098         }
1099
1100         #[test]
1101         #[should_panic]
1102         fn test_package_untractable_merge_from() {
1103                 let txid = Txid::from_hex("c2d4449afa8d26140898dd54d3390b057ba2a5afcf03ba29d7dc0d8b9ffe966e").unwrap();
1104                 let secp_ctx = Secp256k1::new();
1105                 let htlc_outp = dumb_htlc_output!();
1106                 let revk_outp = dumb_revk_output!(secp_ctx);
1107
1108                 let mut malleable_package = PackageTemplate::build_package(txid, 0, htlc_outp.clone(), 1000, true, 100);
1109                 let untractable_package = PackageTemplate::build_package(txid, 1, revk_outp.clone(), 1000, true, 100);
1110                 malleable_package.merge_package(untractable_package);
1111         }
1112
1113         #[test]
1114         #[should_panic]
1115         fn test_package_noaggregation_to() {
1116                 let txid = Txid::from_hex("c2d4449afa8d26140898dd54d3390b057ba2a5afcf03ba29d7dc0d8b9ffe966e").unwrap();
1117                 let secp_ctx = Secp256k1::new();
1118                 let revk_outp = dumb_revk_output!(secp_ctx);
1119
1120                 let mut noaggregation_package = PackageTemplate::build_package(txid, 0, revk_outp.clone(), 1000, false, 100);
1121                 let aggregation_package = PackageTemplate::build_package(txid, 1, revk_outp.clone(), 1000, true, 100);
1122                 noaggregation_package.merge_package(aggregation_package);
1123         }
1124
1125         #[test]
1126         #[should_panic]
1127         fn test_package_noaggregation_from() {
1128                 let txid = Txid::from_hex("c2d4449afa8d26140898dd54d3390b057ba2a5afcf03ba29d7dc0d8b9ffe966e").unwrap();
1129                 let secp_ctx = Secp256k1::new();
1130                 let revk_outp = dumb_revk_output!(secp_ctx);
1131
1132                 let mut aggregation_package = PackageTemplate::build_package(txid, 0, revk_outp.clone(), 1000, true, 100);
1133                 let noaggregation_package = PackageTemplate::build_package(txid, 1, revk_outp.clone(), 1000, false, 100);
1134                 aggregation_package.merge_package(noaggregation_package);
1135         }
1136
1137         #[test]
1138         #[should_panic]
1139         fn test_package_empty() {
1140                 let txid = Txid::from_hex("c2d4449afa8d26140898dd54d3390b057ba2a5afcf03ba29d7dc0d8b9ffe966e").unwrap();
1141                 let secp_ctx = Secp256k1::new();
1142                 let revk_outp = dumb_revk_output!(secp_ctx);
1143
1144                 let mut empty_package = PackageTemplate::build_package(txid, 0, revk_outp.clone(), 1000, true, 100);
1145                 empty_package.inputs = vec![];
1146                 let package = PackageTemplate::build_package(txid, 1, revk_outp.clone(), 1000, true, 100);
1147                 empty_package.merge_package(package);
1148         }
1149
1150         #[test]
1151         #[should_panic]
1152         fn test_package_differing_categories() {
1153                 let txid = Txid::from_hex("c2d4449afa8d26140898dd54d3390b057ba2a5afcf03ba29d7dc0d8b9ffe966e").unwrap();
1154                 let secp_ctx = Secp256k1::new();
1155                 let revk_outp = dumb_revk_output!(secp_ctx);
1156                 let counterparty_outp = dumb_counterparty_output!(secp_ctx, 0, false);
1157
1158                 let mut revoked_package = PackageTemplate::build_package(txid, 0, revk_outp, 1000, true, 100);
1159                 let counterparty_package = PackageTemplate::build_package(txid, 1, counterparty_outp, 1000, true, 100);
1160                 revoked_package.merge_package(counterparty_package);
1161         }
1162
1163         #[test]
1164         fn test_package_split_malleable() {
1165                 let txid = Txid::from_hex("c2d4449afa8d26140898dd54d3390b057ba2a5afcf03ba29d7dc0d8b9ffe966e").unwrap();
1166                 let secp_ctx = Secp256k1::new();
1167                 let revk_outp_one = dumb_revk_output!(secp_ctx);
1168                 let revk_outp_two = dumb_revk_output!(secp_ctx);
1169                 let revk_outp_three = dumb_revk_output!(secp_ctx);
1170
1171                 let mut package_one = PackageTemplate::build_package(txid, 0, revk_outp_one, 1000, true, 100);
1172                 let package_two = PackageTemplate::build_package(txid, 1, revk_outp_two, 1000, true, 100);
1173                 let package_three = PackageTemplate::build_package(txid, 2, revk_outp_three, 1000, true, 100);
1174
1175                 package_one.merge_package(package_two);
1176                 package_one.merge_package(package_three);
1177                 assert_eq!(package_one.outpoints().len(), 3);
1178
1179                 if let Some(split_package) = package_one.split_package(&BitcoinOutPoint { txid, vout: 1 }) {
1180                         // Packages attributes should be identical
1181                         assert!(split_package.is_malleable());
1182                         assert_eq!(split_package.soonest_conf_deadline, package_one.soonest_conf_deadline);
1183                         assert_eq!(split_package.aggregable, package_one.aggregable);
1184                         assert_eq!(split_package.feerate_previous, package_one.feerate_previous);
1185                         assert_eq!(split_package.height_timer, package_one.height_timer);
1186                         assert_eq!(split_package.height_original, package_one.height_original);
1187                 } else { panic!(); }
1188                 assert_eq!(package_one.outpoints().len(), 2);
1189         }
1190
1191         #[test]
1192         fn test_package_split_untractable() {
1193                 let txid = Txid::from_hex("c2d4449afa8d26140898dd54d3390b057ba2a5afcf03ba29d7dc0d8b9ffe966e").unwrap();
1194                 let htlc_outp_one = dumb_htlc_output!();
1195
1196                 let mut package_one = PackageTemplate::build_package(txid, 0, htlc_outp_one, 1000, true, 100);
1197                 let ret_split = package_one.split_package(&BitcoinOutPoint { txid, vout: 0});
1198                 assert!(ret_split.is_none());
1199         }
1200
1201         #[test]
1202         fn test_package_timer() {
1203                 let txid = Txid::from_hex("c2d4449afa8d26140898dd54d3390b057ba2a5afcf03ba29d7dc0d8b9ffe966e").unwrap();
1204                 let secp_ctx = Secp256k1::new();
1205                 let revk_outp = dumb_revk_output!(secp_ctx);
1206
1207                 let mut package = PackageTemplate::build_package(txid, 0, revk_outp, 1000, true, 100);
1208                 assert_eq!(package.timer(), 100);
1209                 package.set_timer(101);
1210                 assert_eq!(package.timer(), 101);
1211         }
1212
1213         #[test]
1214         fn test_package_amounts() {
1215                 let txid = Txid::from_hex("c2d4449afa8d26140898dd54d3390b057ba2a5afcf03ba29d7dc0d8b9ffe966e").unwrap();
1216                 let secp_ctx = Secp256k1::new();
1217                 let counterparty_outp = dumb_counterparty_output!(secp_ctx, 1_000_000, false);
1218
1219                 let package = PackageTemplate::build_package(txid, 0, counterparty_outp, 1000, true, 100);
1220                 assert_eq!(package.package_amount(), 1000);
1221         }
1222
1223         #[test]
1224         fn test_package_weight() {
1225                 let txid = Txid::from_hex("c2d4449afa8d26140898dd54d3390b057ba2a5afcf03ba29d7dc0d8b9ffe966e").unwrap();
1226                 let secp_ctx = Secp256k1::new();
1227
1228                 // (nVersion (4) + nLocktime (4) + count_tx_in (1) + prevout (36) + sequence (4) + script_length (1) + count_tx_out (1) + value (8) + var_int (1)) * WITNESS_SCALE_FACTOR + witness marker (2)
1229                 let weight_sans_output = (4 + 4 + 1 + 36 + 4 + 1 + 1 + 8 + 1) * WITNESS_SCALE_FACTOR + 2;
1230
1231                 {
1232                         let revk_outp = dumb_revk_output!(secp_ctx);
1233                         let package = PackageTemplate::build_package(txid, 0, revk_outp, 0, true, 100);
1234                         assert_eq!(package.package_weight(&Script::new()),  weight_sans_output + WEIGHT_REVOKED_OUTPUT as usize);
1235                 }
1236
1237                 {
1238                         for &opt_anchors in [false, true].iter() {
1239                                 let counterparty_outp = dumb_counterparty_output!(secp_ctx, 1_000_000, opt_anchors);
1240                                 let package = PackageTemplate::build_package(txid, 0, counterparty_outp, 1000, true, 100);
1241                                 assert_eq!(package.package_weight(&Script::new()), weight_sans_output + weight_received_htlc(opt_anchors) as usize);
1242                         }
1243                 }
1244
1245                 {
1246                         for &opt_anchors in [false, true].iter() {
1247                                 let counterparty_outp = dumb_counterparty_offered_output!(secp_ctx, 1_000_000, opt_anchors);
1248                                 let package = PackageTemplate::build_package(txid, 0, counterparty_outp, 1000, true, 100);
1249                                 assert_eq!(package.package_weight(&Script::new()), weight_sans_output + weight_offered_htlc(opt_anchors) as usize);
1250                         }
1251                 }
1252         }
1253 }