_ Git - rust-lightning/blob - 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, SigHashType};
  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::key::{SecretKey,PublicKey};
  22
  23 use ln::PaymentPreimage;
  24 use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment, HTLC_OUTPUT_IN_COMMITMENT_SIZE};
  25 use ln::chan_utils;
  26 use ln::msgs::DecodeError;
  27 use chain::chaininterface::{FeeEstimator, ConfirmationTarget, MIN_RELAY_FEE_SAT_PER_1000_WEIGHT};
  28 use chain::keysinterface::Sign;
  29 use chain::onchaintx::OnchainTxHandler;
  30 use util::byte_utils;
  31 use util::logger::Logger;
  32 use util::ser::{Readable, Writer, Writeable};
  33
  34 use std::cmp;
  35 use std::mem;
  36 use std::ops::Deref;
  37
  38 const MAX_ALLOC_SIZE: usize = 64*1024;
  39
  40
  41 // number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
  42 pub(crate) const WEIGHT_REVOKED_OFFERED_HTLC: u64 = 1 + 1 + 73 + 1 + 33 + 1 + 133;
  43 // number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
  44 pub(crate) const WEIGHT_REVOKED_RECEIVED_HTLC: u64 = 1 + 1 + 73 + 1 + 33 + 1 +  139;
  45 // number_of_witness_elements + sig_length + counterpartyhtlc_sig  + preimage_length + preimage + witness_script_length + witness_script
  46 pub(crate) const WEIGHT_OFFERED_HTLC: u64 = 1 + 1 + 73 + 1 + 32 + 1 + 133;
  47 // number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
  48 pub(crate) const WEIGHT_RECEIVED_HTLC: u64 = 1 + 1 + 73 + 1 + 1 + 1 + 139;
  49 // number_of_witness_elements + sig_length + revocation_sig + true_length + op_true + witness_script_length + witness_script
  50 pub(crate) const WEIGHT_REVOKED_OUTPUT: u64 = 1 + 1 + 73 + 1 + 1 + 1 + 77;
  51
  52 /// Height delay at which transactions are fee-bumped/rebroadcasted with a low priority.
  53 const LOW_FREQUENCY_BUMP_INTERVAL: u32 = 15;
  54 /// Height delay at which transactions are fee-bumped/rebroadcasted with a middle priority.
  55 const MIDDLE_FREQUENCY_BUMP_INTERVAL: u32 = 3;
  56 /// Height delay at which transactions are fee-bumped/rebroadcasted with a high priority.
  57 const HIGH_FREQUENCY_BUMP_INTERVAL: u32 = 1;
  58
  59 /// A struct to describe a revoked output and corresponding information to generate a solving
  60 /// witness spending a commitment `to_local` output or a second-stage HTLC transaction output.
  61 ///
  62 /// CSV and pubkeys are used as part of a witnessScript redeeming a balance output, amount is used
  63 /// as part of the signature hash and revocation secret to generate a satisfying witness.
  64 #[derive(Clone, PartialEq)]
  65 pub(crate) struct RevokedOutput {
  66         per_commitment_point: PublicKey,
  67         counterparty_delayed_payment_base_key: PublicKey,
  68         counterparty_htlc_base_key: PublicKey,
  69         per_commitment_key: SecretKey,
  70         weight: u64,
  71         amount: u64,
  72         on_counterparty_tx_csv: u16,
  73 }
  74
  75 impl RevokedOutput {
  76         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 {
  77                 RevokedOutput {
  78                         per_commitment_point,
  79                         counterparty_delayed_payment_base_key,
  80                         counterparty_htlc_base_key,
  81                         per_commitment_key,
  82                         weight: WEIGHT_REVOKED_OUTPUT,
  83                         amount,
  84                         on_counterparty_tx_csv
  85                 }
  86         }
  87 }
  88
  89 impl_writeable!(RevokedOutput, 33*3 + 32 + 8 + 8 + 2, {
  90         per_commitment_point,
  91         counterparty_delayed_payment_base_key,
  92         counterparty_htlc_base_key,
  93         per_commitment_key,
  94         weight,
  95         amount,
  96         on_counterparty_tx_csv
  97 });
  98
  99 /// A struct to describe a revoked offered output and corresponding information to generate a
 100 /// solving witness.
 101 ///
 102 /// HTLCOuputInCommitment (hash timelock, direction) and pubkeys are used to generate a suitable
 103 /// witnessScript.
 104 ///
 105 /// CSV is used as part of a witnessScript redeeming a balance output, amount is used as part
 106 /// of the signature hash and revocation secret to generate a satisfying witness.
 107 #[derive(Clone, PartialEq)]
 108 pub(crate) struct RevokedHTLCOutput {
 109         per_commitment_point: PublicKey,
 110         counterparty_delayed_payment_base_key: PublicKey,
 111         counterparty_htlc_base_key: PublicKey,
 112         per_commitment_key: SecretKey,
 113         weight: u64,
 114         amount: u64,
 115         htlc: HTLCOutputInCommitment,
 116 }
 117
 118 impl RevokedHTLCOutput {
 119         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) -> Self {
 120                 let weight = if htlc.offered { WEIGHT_REVOKED_OFFERED_HTLC } else { WEIGHT_REVOKED_RECEIVED_HTLC };
 121                 RevokedHTLCOutput {
 122                         per_commitment_point,
 123                         counterparty_delayed_payment_base_key,
 124                         counterparty_htlc_base_key,
 125                         per_commitment_key,
 126                         weight,
 127                         amount,
 128                         htlc
 129                 }
 130         }
 131 }
 132
 133 impl_writeable!(RevokedHTLCOutput, 33*3 + 32 + 8 + 8 + HTLC_OUTPUT_IN_COMMITMENT_SIZE, {
 134         per_commitment_point,
 135         counterparty_delayed_payment_base_key,
 136         counterparty_htlc_base_key,
 137         per_commitment_key,
 138         weight,
 139         amount,
 140         htlc
 141 });
 142
 143 /// A struct to describe a HTLC output on a counterparty commitment transaction.
 144 ///
 145 /// HTLCOutputInCommitment (hash, timelock, directon) and pubkeys are used to generate a suitable
 146 /// witnessScript.
 147 ///
 148 /// The preimage is used as part of the witness.
 149 #[derive(Clone, PartialEq)]
 150 pub(crate) struct CounterpartyOfferedHTLCOutput {
 151         per_commitment_point: PublicKey,
 152         counterparty_delayed_payment_base_key: PublicKey,
 153         counterparty_htlc_base_key: PublicKey,
 154         preimage: PaymentPreimage,
 155         htlc: HTLCOutputInCommitment
 156 }
 157
 158 impl CounterpartyOfferedHTLCOutput {
 159         pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: PublicKey, counterparty_htlc_base_key: PublicKey, preimage: PaymentPreimage, htlc: HTLCOutputInCommitment) -> Self {
 160                 CounterpartyOfferedHTLCOutput {
 161                         per_commitment_point,
 162                         counterparty_delayed_payment_base_key,
 163                         counterparty_htlc_base_key,
 164                         preimage,
 165                         htlc
 166                 }
 167         }
 168 }
 169
 170 impl_writeable!(CounterpartyOfferedHTLCOutput, 33*3 + 32 + HTLC_OUTPUT_IN_COMMITMENT_SIZE, {
 171         per_commitment_point,
 172         counterparty_delayed_payment_base_key,
 173         counterparty_htlc_base_key,
 174         preimage,
 175         htlc
 176 });
 177
 178 /// A struct to describe a HTLC output on a counterparty commitment transaction.
 179 ///
 180 /// HTLCOutputInCommitment (hash, timelock, directon) and pubkeys are used to generate a suitable
 181 /// witnessScript.
 182 #[derive(Clone, PartialEq)]
 183 pub(crate) struct CounterpartyReceivedHTLCOutput {
 184         per_commitment_point: PublicKey,
 185         counterparty_delayed_payment_base_key: PublicKey,
 186         counterparty_htlc_base_key: PublicKey,
 187         htlc: HTLCOutputInCommitment
 188 }
 189
 190 impl CounterpartyReceivedHTLCOutput {
 191         pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: PublicKey, counterparty_htlc_base_key: PublicKey, htlc: HTLCOutputInCommitment) -> Self {
 192                 CounterpartyReceivedHTLCOutput {
 193                         per_commitment_point,
 194                         counterparty_delayed_payment_base_key,
 195                         counterparty_htlc_base_key,
 196                         htlc
 197                 }
 198         }
 199 }
 200
 201 impl_writeable!(CounterpartyReceivedHTLCOutput, 33*3 + HTLC_OUTPUT_IN_COMMITMENT_SIZE, {
 202         per_commitment_point,
 203         counterparty_delayed_payment_base_key,
 204         counterparty_htlc_base_key,
 205         htlc
 206 });
 207
 208 /// A struct to describe a HTLC output on holder commitment transaction.
 209 ///
 210 /// Either offered or received, the amount is always used as part of the bip143 sighash.
 211 /// Preimage is only included as part of the witness in former case.
 212 #[derive(Clone, PartialEq)]
 213 pub(crate) struct HolderHTLCOutput {
 214         preimage: Option<PaymentPreimage>,
 215         amount: u64,
 216 }
 217
 218 impl HolderHTLCOutput {
 219         pub(crate) fn build(preimage: Option<PaymentPreimage>, amount: u64) -> Self {
 220                 HolderHTLCOutput {
 221                         preimage,
 222                         amount
 223                 }
 224         }
 225 }
 226
 227 impl_writeable!(HolderHTLCOutput, 0, {
 228         preimage,
 229         amount
 230 });
 231
 232 /// A struct to describe the channel output on the funding transaction.
 233 ///
 234 /// witnessScript is used as part of the witness redeeming the funding utxo.
 235 #[derive(Clone, PartialEq)]
 236 pub(crate) struct HolderFundingOutput {
 237         funding_redeemscript: Script,
 238 }
 239
 240 impl HolderFundingOutput {
 241         pub(crate) fn build(funding_redeemscript: Script) -> Self {
 242                 HolderFundingOutput {
 243                         funding_redeemscript,
 244                 }
 245         }
 246 }
 247
 248 impl_writeable!(HolderFundingOutput, 0, {
 249         funding_redeemscript
 250 });
 251
 252 /// A wrapper encapsulating all in-protocol differing outputs types.
 253 ///
 254 /// The generic API offers access to an outputs common attributes or allow transformation such as
 255 /// finalizing an input claiming the output.
 256 #[derive(Clone, PartialEq)]
 257 pub(crate) enum PackageSolvingData {
 258         RevokedOutput(RevokedOutput),
 259         RevokedHTLCOutput(RevokedHTLCOutput),
 260         CounterpartyOfferedHTLCOutput(CounterpartyOfferedHTLCOutput),
 261         CounterpartyReceivedHTLCOutput(CounterpartyReceivedHTLCOutput),
 262         HolderHTLCOutput(HolderHTLCOutput),
 263         HolderFundingOutput(HolderFundingOutput),
 264 }
 265
 266 impl PackageSolvingData {
 267         fn amount(&self) -> u64 {
 268                 let amt = match self {
 269                         PackageSolvingData::RevokedOutput(ref outp) => { outp.amount },
 270                         PackageSolvingData::RevokedHTLCOutput(ref outp) => { outp.amount },
 271                         PackageSolvingData::CounterpartyOfferedHTLCOutput(ref outp) => { outp.htlc.amount_msat / 1000 },
 272                         PackageSolvingData::CounterpartyReceivedHTLCOutput(ref outp) => { outp.htlc.amount_msat / 1000 },
 273                         // Note: Currently, amounts of holder outputs spending witnesses aren't used
 274                         // as we can't malleate spending package to increase their feerate. This
 275                         // should change with the remaining anchor output patchset.
 276                         PackageSolvingData::HolderHTLCOutput(..) => { 0 },
 277                         PackageSolvingData::HolderFundingOutput(..) => { 0 },
 278                 };
 279                 amt
 280         }
 281         fn weight(&self) -> usize {
 282                 let weight = match self {
 283                         PackageSolvingData::RevokedOutput(ref outp) => { outp.weight as usize },
 284                         PackageSolvingData::RevokedHTLCOutput(ref outp) => { outp.weight as usize },
 285                         PackageSolvingData::CounterpartyOfferedHTLCOutput(..) => { WEIGHT_OFFERED_HTLC as usize },
 286                         PackageSolvingData::CounterpartyReceivedHTLCOutput(..) => { WEIGHT_RECEIVED_HTLC as usize },
 287                         // Note: Currently, weights of holder outputs spending witnesses aren't used
 288                         // as we can't malleate spending package to increase their feerate. This
 289                         // should change with the remaining anchor output patchset.
 290                         PackageSolvingData::HolderHTLCOutput(..) => { debug_assert!(false); 0 },
 291                         PackageSolvingData::HolderFundingOutput(..) => { debug_assert!(false); 0 },
 292                 };
 293                 weight
 294         }
 295         fn is_compatible(&self, input: &PackageSolvingData) -> bool {
 296                 match self {
 297                         PackageSolvingData::RevokedOutput(..) => {
 298                                 match input {
 299                                         PackageSolvingData::RevokedHTLCOutput(..) => { true },
 300                                         PackageSolvingData::RevokedOutput(..) => { true },
 301                                         _ => { false }
 302                                 }
 303                         },
 304                         PackageSolvingData::RevokedHTLCOutput(..) => {
 305                                 match input {
 306                                         PackageSolvingData::RevokedOutput(..) => { true },
 307                                         PackageSolvingData::RevokedHTLCOutput(..) => { true },
 308                                         _ => { false }
 309                                 }
 310                         },
 311                         _ => { mem::discriminant(self) == mem::discriminant(&input) }
 312                 }
 313         }
 314         fn finalize_input<Signer: Sign>(&self, bumped_tx: &mut Transaction, i: usize, onchain_handler: &mut OnchainTxHandler<Signer>) -> bool {
 315                 match self {
 316                         PackageSolvingData::RevokedOutput(ref outp) => {
 317                                 if let Ok(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) {
 318                                         let witness_script = chan_utils::get_revokeable_redeemscript(&chan_keys.revocation_key, outp.on_counterparty_tx_csv, &chan_keys.broadcaster_delayed_payment_key);
 319                                         //TODO: should we panic on signer failure ?
 320                                         if let Ok(sig) = onchain_handler.signer.sign_justice_revoked_output(&bumped_tx, i, outp.amount, &outp.per_commitment_key, &onchain_handler.secp_ctx) {
 321                                                 bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
 322                                                 bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
 323                                                 bumped_tx.input[i].witness.push(vec!(1));
 324                                                 bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
 325                                         } else { return false; }
 326                                 }
 327                         },
 328                         PackageSolvingData::RevokedHTLCOutput(ref outp) => {
 329                                 if let Ok(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) {
 330                                         let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&outp.htlc, &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);
 331                                         //TODO: should we panic on signer failure ?
 332                                         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) {
 333                                                 bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
 334                                                 bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
 335                                                 bumped_tx.input[i].witness.push(chan_keys.revocation_key.clone().serialize().to_vec());
 336                                                 bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
 337                                         } else { return false; }
 338                                 }
 339                         },
 340                         PackageSolvingData::CounterpartyOfferedHTLCOutput(ref outp) => {
 341                                 if let Ok(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) {
 342                                         let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&outp.htlc, &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);
 343
 344                                         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) {
 345                                                 bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
 346                                                 bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
 347                                                 bumped_tx.input[i].witness.push(outp.preimage.0.to_vec());
 348                                                 bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
 349                                         }
 350                                 }
 351                         },
 352                         PackageSolvingData::CounterpartyReceivedHTLCOutput(ref outp) => {
 353                                 if let Ok(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) {
 354                                         let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&outp.htlc, &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);
 355
 356                                         bumped_tx.lock_time = outp.htlc.cltv_expiry; // Right now we don't aggregate time-locked transaction, if we do we should set lock_time before to avoid breaking hash computation
 357                                         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) {
 358                                                 bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
 359                                                 bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
 360                                                 // Due to BIP146 (MINIMALIF) this must be a zero-length element to relay.
 361                                                 bumped_tx.input[i].witness.push(vec![]);
 362                                                 bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
 363                                         }
 364                                 }
 365                         },
 366                         _ => { panic!("API Error!"); }
 367                 }
 368                 true
 369         }
 370         fn get_finalized_tx<Signer: Sign>(&self, outpoint: &BitcoinOutPoint, onchain_handler: &mut OnchainTxHandler<Signer>) -> Option<Transaction> {
 371                 match self {
 372                         PackageSolvingData::HolderHTLCOutput(ref outp) => { return onchain_handler.get_fully_signed_htlc_tx(outpoint, &outp.preimage); }
 373                         PackageSolvingData::HolderFundingOutput(ref outp) => { return Some(onchain_handler.get_fully_signed_holder_tx(&outp.funding_redeemscript)); }
 374                         _ => { panic!("API Error!"); }
 375                 }
 376         }
 377 }
 378
 379 impl Writeable for PackageSolvingData {
 380         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
 381                 match self {
 382                         PackageSolvingData::RevokedOutput(ref revoked_outp) => {
 383                                 0u8.write(writer)?;
 384                                 revoked_outp.write(writer)?;
 385                         },
 386                         PackageSolvingData::RevokedHTLCOutput(ref revoked_outp) => {
 387                                 1u8.write(writer)?;
 388                                 revoked_outp.write(writer)?;
 389                         },
 390                         PackageSolvingData::CounterpartyOfferedHTLCOutput(ref counterparty_outp) => {
 391                                 2u8.write(writer)?;
 392                                 counterparty_outp.write(writer)?;
 393                         },
 394                         PackageSolvingData::CounterpartyReceivedHTLCOutput(ref counterparty_outp) => {
 395                                 3u8.write(writer)?;
 396                                 counterparty_outp.write(writer)?;
 397                         },
 398                         PackageSolvingData::HolderHTLCOutput(ref holder_outp) => {
 399                                 4u8.write(writer)?;
 400                                 holder_outp.write(writer)?;
 401                         },
 402                         PackageSolvingData::HolderFundingOutput(ref funding_outp) => {
 403                                 5u8.write(writer)?;
 404                                 funding_outp.write(writer)?;
 405                         }
 406                 }
 407                 Ok(())
 408         }
 409 }
 410
 411 impl Readable for PackageSolvingData {
 412         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 413                 let byte = <u8 as Readable>::read(reader)?;
 414                 let solving_data = match byte {
 415                         0 => {
 416                                 PackageSolvingData::RevokedOutput(Readable::read(reader)?)
 417                         },
 418                         1 => {
 419                                 PackageSolvingData::RevokedHTLCOutput(Readable::read(reader)?)
 420                         },
 421                         2 => {
 422                                 PackageSolvingData::CounterpartyOfferedHTLCOutput(Readable::read(reader)?)
 423                         },
 424                         3 => {
 425                                 PackageSolvingData::CounterpartyReceivedHTLCOutput(Readable::read(reader)?)
 426                         },
 427                         4 => {
 428                                 PackageSolvingData::HolderHTLCOutput(Readable::read(reader)?)
 429                         },
 430                         5 => {
 431                                 PackageSolvingData::HolderFundingOutput(Readable::read(reader)?)
 432                         }
 433                         _ => return Err(DecodeError::UnknownVersion)
 434                 };
 435                 Ok(solving_data)
 436         }
 437 }
 438
 439 /// A malleable package might be aggregated with other packages to save on fees.
 440 /// A untractable package has been counter-signed and aggregable will break cached counterparty
 441 /// signatures.
 442 #[derive(Clone, PartialEq)]
 443 pub(crate) enum PackageMalleability {
 444         Malleable,
 445         Untractable,
 446 }
 447
 448 /// A structure to describe a package content that is generated by ChannelMonitor and
 449 /// used by OnchainTxHandler to generate and broadcast transactions settling onchain claims.
 450 ///
 451 /// A package is defined as one or more transactions claiming onchain outputs in reaction
 452 /// to confirmation of a channel transaction. Those packages might be aggregated to save on
 453 /// fees, if satisfaction of outputs's witnessScript let's us do so.
 454 ///
 455 /// As packages are time-sensitive, we fee-bump and rebroadcast them at scheduled intervals.
 456 /// Failing to confirm a package translate as a loss of funds for the user.
 457 #[derive(Clone, PartialEq)]
 458 pub struct PackageTemplate {
 459         // List of onchain outputs and solving data to generate satisfying witnesses.
 460         inputs: Vec<(BitcoinOutPoint, PackageSolvingData)>,
 461         // Packages are deemed as malleable if we have local knwoledge of at least one set of
 462         // private keys yielding a satisfying witnesses. Malleability implies that we can aggregate
 463         // packages among them to save on fees or rely on RBF to bump their feerates.
 464         // Untractable packages have been counter-signed and thus imply that we can't aggregate
 465         // them without breaking signatures. Fee-bumping strategy will also rely on CPFP.
 466         malleability: PackageMalleability,
 467         // Block height after which the earlier-output belonging to this package is mature for a
 468         // competing claim by the counterparty. As our chain tip becomes nearer from the timelock,
 469         // the fee-bumping frequency will increase. See `OnchainTxHandler::get_height_timer`.
 470         soonest_conf_deadline: u32,
 471         // Determines if this package can be aggregated.
 472         // Timelocked outputs belonging to the same transaction might have differing
 473         // satisfying heights. Picking up the later height among the output set would be a valid
 474         // aggregable strategy but it comes with at least 2 trade-offs :
 475         // * earlier-output fund are going to take longer to come back
 476         // * CLTV delta backing up a corresponding HTLC on an upstream channel could be swallowed
 477         // by the requirement of the later-output part of the set
 478         // For now, we mark such timelocked outputs as non-aggregable, though we might introduce
 479         // smarter aggregable strategy in the future.
 480         aggregable: bool,
 481         // Cache of package feerate committed at previous (re)broadcast. If bumping resources
 482         // (either claimed output value or external utxo), it will keep increasing until holder
 483         // or counterparty successful claim.
 484         feerate_previous: u64,
 485         // Cache of next height at which fee-bumping and rebroadcast will be attempted. In
 486         // the future, we might abstract it to an observed mempool fluctuation.
 487         height_timer: Option<u32>,
 488         // Confirmation height of the claimed outputs set transaction. In case of reorg reaching
 489         // it, we wipe out and forget the package.
 490         height_original: u32,
 491 }
 492
 493 impl PackageTemplate {
 494         pub(crate) fn is_malleable(&self) -> bool {
 495                 self.malleability == PackageMalleability::Malleable
 496         }
 497         pub(crate) fn timelock(&self) -> u32 {
 498                 self.soonest_conf_deadline
 499         }
 500         pub(crate) fn aggregable(&self) -> bool {
 501                 self.aggregable
 502         }
 503         pub(crate) fn set_feerate(&mut self, new_feerate: u64) {
 504                 self.feerate_previous = new_feerate;
 505         }
 506         pub(crate) fn timer(&self) -> Option<u32> {
 507                 if let Some(ref timer) = self.height_timer {
 508                         return Some(*timer);
 509                 }
 510                 None
 511         }
 512         pub(crate) fn set_timer(&mut self, new_timer: Option<u32>) {
 513                 self.height_timer = new_timer;
 514         }
 515         pub(crate) fn outpoints(&self) -> Vec<&BitcoinOutPoint> {
 516                 self.inputs.iter().map(|(o, _)| o).collect()
 517         }
 518         pub(crate) fn split_package(&mut self, split_outp: &BitcoinOutPoint) -> Option<PackageTemplate> {
 519                 match self.malleability {
 520                         PackageMalleability::Malleable => {
 521                                 let mut split_package = None;
 522                                 let timelock = self.soonest_conf_deadline;
 523                                 let aggregable = self.aggregable;
 524                                 let feerate_previous = self.feerate_previous;
 525                                 let height_timer = self.height_timer;
 526                                 let height_original = self.height_original;
 527                                 self.inputs.retain(|outp| {
 528                                         if *split_outp == outp.0 {
 529                                                 split_package = Some(PackageTemplate {
 530                                                         inputs: vec![(outp.0, outp.1.clone())],
 531                                                         malleability: PackageMalleability::Malleable,
 532                                                         soonest_conf_deadline: timelock,
 533                                                         aggregable,
 534                                                         feerate_previous,
 535                                                         height_timer,
 536                                                         height_original,
 537                                                 });
 538                                                 return false;
 539                                         }
 540                                         return true;
 541                                 });
 542                                 return split_package;
 543                         },
 544                         _ => {
 545                                 // Note, we may try to split on remote transaction for
 546                                 // which we don't have a competing one (HTLC-Success before
 547                                 // timelock expiration). This explain we don't panic!
 548                                 // We should refactor OnchainTxHandler::block_connected to
 549                                 // only test equality on competing claims.
 550                                 return None;
 551                         }
 552                 }
 553         }
 554         pub(crate) fn merge_package(&mut self, mut merge_from: PackageTemplate) {
 555                 assert_eq!(self.height_original, merge_from.height_original);
 556                 if self.malleability == PackageMalleability::Untractable || merge_from.malleability == PackageMalleability::Untractable {
 557                         panic!("Merging template on untractable packages");
 558                 }
 559                 if !self.aggregable || !merge_from.aggregable {
 560                         panic!("Merging non aggregatable packages");
 561                 }
 562                 if let Some((_, lead_input)) = self.inputs.first() {
 563                         for (_, v) in merge_from.inputs.iter() {
 564                                 if !lead_input.is_compatible(v) { panic!("Merging outputs from differing types !"); }
 565                         }
 566                 } else { panic!("Merging template on an empty package"); }
 567                 for (k, v) in merge_from.inputs.drain(..) {
 568                         self.inputs.push((k, v));
 569                 }
 570                 //TODO: verify coverage and sanity?
 571                 if self.soonest_conf_deadline > merge_from.soonest_conf_deadline {
 572                         self.soonest_conf_deadline = merge_from.soonest_conf_deadline;
 573                 }
 574                 if self.feerate_previous > merge_from.feerate_previous {
 575                         self.feerate_previous = merge_from.feerate_previous;
 576                 }
 577                 self.height_timer = cmp::min(self.height_timer, merge_from.height_timer);
 578         }
 579         pub(crate) fn package_amount(&self) -> u64 {
 580                 let mut amounts = 0;
 581                 for (_, outp) in self.inputs.iter() {
 582                         amounts += outp.amount();
 583                 }
 584                 amounts
 585         }
 586         pub(crate) fn package_weight(&self, destination_script: &Script) -> usize {
 587                 let mut inputs_weight = 0;
 588                 let mut witnesses_weight = 2; // count segwit flags
 589                 for (_, outp) in self.inputs.iter() {
 590                         // previous_out_point: 36 bytes ; var_int: 1 byte ; sequence: 4 bytes
 591                         inputs_weight += 41 * WITNESS_SCALE_FACTOR;
 592                         witnesses_weight += outp.weight();
 593                 }
 594                 // version: 4 bytes ; count_tx_in: 1 byte ; count_tx_out: 1 byte ; lock_time: 4 bytes
 595                 let transaction_weight = 10 * WITNESS_SCALE_FACTOR;
 596                 // value: 8 bytes ; var_int: 1 byte ; pk_script: `destination_script.len()`
 597                 let output_weight = (8 + 1 + destination_script.len()) * WITNESS_SCALE_FACTOR;
 598                 inputs_weight + witnesses_weight + transaction_weight + output_weight
 599         }
 600         pub(crate) fn finalize_package<L: Deref, Signer: Sign>(&self, onchain_handler: &mut OnchainTxHandler<Signer>, value: u64, destination_script: Script, logger: &L) -> Option<Transaction>
 601                 where L::Target: Logger,
 602         {
 603                 match self.malleability {
 604                         PackageMalleability::Malleable => {
 605                                 let mut bumped_tx = Transaction {
 606                                         version: 2,
 607                                         lock_time: 0,
 608                                         input: vec![],
 609                                         output: vec![TxOut {
 610                                                 script_pubkey: destination_script,
 611                                                 value,
 612                                         }],
 613                                 };
 614                                 for (outpoint, _) in self.inputs.iter() {
 615                                         bumped_tx.input.push(TxIn {
 616                                                 previous_output: *outpoint,
 617                                                 script_sig: Script::new(),
 618                                                 sequence: 0xfffffffd,
 619                                                 witness: Vec::new(),
 620                                         });
 621                                 }
 622                                 for (i, (outpoint, out)) in self.inputs.iter().enumerate() {
 623                                         log_trace!(logger, "Adding claiming input for outpoint {}:{}", outpoint.txid, outpoint.vout);
 624                                         if !out.finalize_input(&mut bumped_tx, i, onchain_handler) { return None; }
 625                                 }
 626                                 log_trace!(logger, "Finalized transaction {} ready to broadcast", bumped_tx.txid());
 627                                 return Some(bumped_tx);
 628                         },
 629                         PackageMalleability::Untractable => {
 630                                 if let Some((outpoint, outp)) = self.inputs.first() {
 631                                         if let Some(final_tx) = outp.get_finalized_tx(outpoint, onchain_handler) {
 632                                                 log_trace!(logger, "Adding claiming input for outpoint {}:{}", outpoint.txid, outpoint.vout);
 633                                                 log_trace!(logger, "Finalized transaction {} ready to broadcast", final_tx.txid());
 634                                                 return Some(final_tx);
 635                                         }
 636                                         return None;
 637                                 } else { panic!("API Error: Package must not be inputs empty"); }
 638                         },
 639                 }
 640         }
 641         /// In LN, output claimed are time-sensitive, which means we have to spend them before reaching some timelock expiration. At in-channel
 642         /// 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
 643         /// height that once reached we should generate a new bumped "version" of the claim tx to be sure that we safely claim outputs before
 644         /// that our counterparty can do so. If timelock expires soon, height timer is going to be scaled down in consequence to increase
 645         /// frequency of the bump and so increase our bets of success.
 646         pub(crate) fn get_height_timer(&self, current_height: u32) -> u32 {
 647                 if self.soonest_conf_deadline <= current_height + MIDDLE_FREQUENCY_BUMP_INTERVAL {
 648                         return current_height + HIGH_FREQUENCY_BUMP_INTERVAL
 649                 } else if self.soonest_conf_deadline - current_height <= LOW_FREQUENCY_BUMP_INTERVAL {
 650                         return current_height + MIDDLE_FREQUENCY_BUMP_INTERVAL
 651                 }
 652                 current_height + LOW_FREQUENCY_BUMP_INTERVAL
 653         }
 654         /// Returns value in satoshis to be included as package outgoing output amount and feerate with which package finalization should be done.
 655         pub(crate) fn compute_package_output<F: Deref, L: Deref>(&self, predicted_weight: usize, input_amounts: u64, fee_estimator: &F, logger: &L) -> Option<(u64, u64)>
 656                 where F::Target: FeeEstimator,
 657                       L::Target: Logger,
 658         {
 659                 // If old feerate is 0, first iteration of this claim, use normal fee calculation
 660                 if self.feerate_previous != 0 {
 661                         if let Some((new_fee, feerate)) = feerate_bump(predicted_weight, input_amounts, self.feerate_previous, fee_estimator, logger) {
 662                                 // If new computed fee is superior at the whole claimable amount burn all in fees
 663                                 if new_fee > input_amounts {
 664                                         return Some((0, feerate));
 665                                 } else {
 666                                         return Some((input_amounts - new_fee, feerate));
 667                                 }
 668                         }
 669                 } else {
 670                         if let Some((new_fee, feerate)) = compute_fee_from_spent_amounts(input_amounts, predicted_weight, fee_estimator, logger) {
 671                                 return Some((input_amounts - new_fee, feerate));
 672                         }
 673                 }
 674                 None
 675         }
 676         pub (crate) fn build_package(txid: Txid, vout: u32, input_solving_data: PackageSolvingData, soonest_conf_deadline: u32, aggregable: bool, height_original: u32) -> Self {
 677                 let malleability = match input_solving_data {
 678                         PackageSolvingData::RevokedOutput(..) => { PackageMalleability::Malleable },
 679                         PackageSolvingData::RevokedHTLCOutput(..) => { PackageMalleability::Malleable },
 680                         PackageSolvingData::CounterpartyOfferedHTLCOutput(..) => { PackageMalleability::Malleable },
 681                         PackageSolvingData::CounterpartyReceivedHTLCOutput(..) => { PackageMalleability::Malleable },
 682                         PackageSolvingData::HolderHTLCOutput(..) => { PackageMalleability::Untractable },
 683                         PackageSolvingData::HolderFundingOutput(..) => { PackageMalleability::Untractable },
 684                 };
 685                 let mut inputs = Vec::with_capacity(1);
 686                 inputs.push((BitcoinOutPoint { txid, vout }, input_solving_data));
 687                 PackageTemplate {
 688                         inputs,
 689                         malleability,
 690                         soonest_conf_deadline,
 691                         aggregable,
 692                         feerate_previous: 0,
 693                         height_timer: None,
 694                         height_original,
 695                 }
 696         }
 697 }
 698
 699 impl Writeable for PackageTemplate {
 700         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
 701                 writer.write_all(&byte_utils::be64_to_array(self.inputs.len() as u64))?;
 702                 for (ref outpoint, ref rev_outp) in self.inputs.iter() {
 703                         outpoint.write(writer)?;
 704                         rev_outp.write(writer)?;
 705                 }
 706                 self.soonest_conf_deadline.write(writer)?;
 707                 self.feerate_previous.write(writer)?;
 708                 self.height_timer.write(writer)?;
 709                 self.height_original.write(writer)?;
 710                 Ok(())
 711         }
 712 }
 713
 714 impl Readable for PackageTemplate {
 715         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 716                 let inputs_count = <u64 as Readable>::read(reader)?;
 717                 let mut inputs: Vec<(BitcoinOutPoint, PackageSolvingData)> = Vec::with_capacity(cmp::min(inputs_count as usize, MAX_ALLOC_SIZE / 128));
 718                 for _ in 0..inputs_count {
 719                         let outpoint = Readable::read(reader)?;
 720                         let rev_outp = Readable::read(reader)?;
 721                         inputs.push((outpoint, rev_outp));
 722                 }
 723                 let (malleability, aggregable) = if let Some((_, lead_input)) = inputs.first() {
 724                         match lead_input {
 725                                 PackageSolvingData::RevokedOutput(..) => { (PackageMalleability::Malleable, true) },
 726                                 PackageSolvingData::RevokedHTLCOutput(..) => { (PackageMalleability::Malleable, true) },
 727                                 PackageSolvingData::CounterpartyOfferedHTLCOutput(..) => { (PackageMalleability::Malleable, true) },
 728                                 PackageSolvingData::CounterpartyReceivedHTLCOutput(..) => { (PackageMalleability::Malleable, false) },
 729                                 PackageSolvingData::HolderHTLCOutput(..) => { (PackageMalleability::Untractable, false) },
 730                                 PackageSolvingData::HolderFundingOutput(..) => { (PackageMalleability::Untractable, false) },
 731                         }
 732                 } else { return Err(DecodeError::InvalidValue); };
 733                 let soonest_conf_deadline = Readable::read(reader)?;
 734                 let feerate_previous = Readable::read(reader)?;
 735                 let height_timer = Readable::read(reader)?;
 736                 let height_original = Readable::read(reader)?;
 737                 Ok(PackageTemplate {
 738                         inputs,
 739                         malleability,
 740                         soonest_conf_deadline,
 741                         aggregable,
 742                         feerate_previous,
 743                         height_timer,
 744                         height_original,
 745                 })
 746         }
 747 }
 748
 749 /// Attempt to propose a bumping fee for a transaction from its spent output's values and predicted
 750 /// weight. We start with the highest priority feerate returned by the node's fee estimator then
 751 /// fall-back to lower priorities until we have enough value available to suck from.
 752 ///
 753 /// If the proposed fee is less than the available spent output's values, we return the proposed
 754 /// fee and the corresponding updated feerate. If the proposed fee is equal or more than the
 755 /// available spent output's values, we return nothing
 756 fn compute_fee_from_spent_amounts<F: Deref, L: Deref>(input_amounts: u64, predicted_weight: usize, fee_estimator: &F, logger: &L) -> Option<(u64, u64)>
 757         where F::Target: FeeEstimator,
 758               L::Target: Logger,
 759 {
 760         let mut updated_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) as u64;
 761         let mut fee = updated_feerate * (predicted_weight as u64) / 1000;
 762         if input_amounts <= fee {
 763                 updated_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Normal) as u64;
 764                 fee = updated_feerate * (predicted_weight as u64) / 1000;
 765                 if input_amounts <= fee {
 766                         updated_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background) as u64;
 767                         fee = updated_feerate * (predicted_weight as u64) / 1000;
 768                         if input_amounts <= fee {
 769                                 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)",
 770                                         fee, input_amounts);
 771                                 None
 772                         } else {
 773                                 log_warn!(logger, "Used low priority fee for on-chain punishment tx as high priority fee was more than the entire claim balance ({} sat)",
 774                                         input_amounts);
 775                                 Some((fee, updated_feerate))
 776                         }
 777                 } else {
 778                         log_warn!(logger, "Used medium priority fee for on-chain punishment tx as high priority fee was more than the entire claim balance ({} sat)",
 779                                 input_amounts);
 780                         Some((fee, updated_feerate))
 781                 }
 782         } else {
 783                 Some((fee, updated_feerate))
 784         }
 785 }
 786
 787 /// Attempt to propose a bumping fee for a transaction from its spent output's values and predicted
 788 /// weight. If feerates proposed by the fee-estimator have been increasing since last fee-bumping
 789 /// attempt, use them. Otherwise, blindly bump the feerate by 25% of the previous feerate. We also
 790 /// verify that those bumping heuristics respect BIP125 rules 3) and 4) and if required adjust
 791 /// the new fee to meet the RBF policy requirement.
 792 fn feerate_bump<F: Deref, L: Deref>(predicted_weight: usize, input_amounts: u64, previous_feerate: u64, fee_estimator: &F, logger: &L) -> Option<(u64, u64)>
 793         where F::Target: FeeEstimator,
 794               L::Target: Logger,
 795 {
 796         // If old feerate inferior to actual one given back by Fee Estimator, use it to compute new fee...
 797         let new_fee = if let Some((new_fee, _)) = compute_fee_from_spent_amounts(input_amounts, predicted_weight, fee_estimator, logger) {
 798                 let updated_feerate = new_fee / (predicted_weight as u64 * 1000);
 799                 if updated_feerate > previous_feerate {
 800                         new_fee
 801                 } else {
 802                         // ...else just increase the previous feerate by 25% (because that's a nice number)
 803                         let new_fee = previous_feerate * (predicted_weight as u64) / 750;
 804                         if input_amounts <= new_fee {
 805                                 log_trace!(logger, "Can't 25% bump new claiming tx, amount {} is too small", input_amounts);
 806                                 return None;
 807                         }
 808                         new_fee
 809                 }
 810         } else {
 811                 log_trace!(logger, "Can't new-estimation bump new claiming tx, amount {} is too small", input_amounts);
 812                 return None;
 813         };
 814
 815         let previous_fee = previous_feerate * (predicted_weight as u64) / 1000;
 816         let min_relay_fee = MIN_RELAY_FEE_SAT_PER_1000_WEIGHT * (predicted_weight as u64) / 1000;
 817         // BIP 125 Opt-in Full Replace-by-Fee Signaling
 818         //      * 3. The replacement transaction pays an absolute fee of at least the sum paid by the original transactions.
 819         //      * 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.
 820         let new_fee = if new_fee < previous_fee + min_relay_fee {
 821                 new_fee + previous_fee + min_relay_fee - new_fee
 822         } else {
 823                 new_fee
 824         };
 825         Some((new_fee, new_fee * 1000 / (predicted_weight as u64)))
 826 }