_ Git - rust-lightning/blob - lightning/src/ln/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 ln::onchaintx::OnchainTxHandler;
  28 use chain::chaininterface::{FeeEstimator, ConfirmationTarget, MIN_RELAY_FEE_SAT_PER_1000_WEIGHT};
  29 use chain::keysinterface::Sign;
  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 /// A struct to describe a revoked output and corresponding information to generate a solving
  53 /// witness spending a commitment `to_local` output or a second-stage HTLC transaction output.
  54 ///
  55 /// CSV and pubkeys are used as part of a witnessScript redeeming a balance output, amount is used
  56 /// as part of the signature hash and revocation secret to generate a satisfying witness.
  57 #[derive(Clone, PartialEq)]
  58 pub(crate) struct RevokedOutput {
  59         per_commitment_point: PublicKey,
  60         counterparty_delayed_payment_base_key: PublicKey,
  61         counterparty_htlc_base_key: PublicKey,
  62         per_commitment_key: SecretKey,
  63         weight: u64,
  64         amount: u64,
  65         on_counterparty_tx_csv: u16,
  66 }
  67
  68 impl RevokedOutput {
  69         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 {
  70                 RevokedOutput {
  71                         per_commitment_point,
  72                         counterparty_delayed_payment_base_key,
  73                         counterparty_htlc_base_key,
  74                         per_commitment_key,
  75                         weight: WEIGHT_REVOKED_OUTPUT,
  76                         amount,
  77                         on_counterparty_tx_csv
  78                 }
  79         }
  80 }
  81
  82 impl_writeable!(RevokedOutput, 33*3 + 32 + 8 + 8 + 2, {
  83         per_commitment_point,
  84         counterparty_delayed_payment_base_key,
  85         counterparty_htlc_base_key,
  86         per_commitment_key,
  87         weight,
  88         amount,
  89         on_counterparty_tx_csv
  90 });
  91
  92 /// A struct to describe a revoked offered output and corresponding information to generate a
  93 /// solving witness.
  94 ///
  95 /// HTLCOuputInCommitment (hash timelock, direction) and pubkeys are used to generate a suitable
  96 /// witnessScript.
  97 ///
  98 /// CSV is used as part of a witnessScript redeeming a balance output, amount is used as part
  99 /// of the signature hash and revocation secret to generate a satisfying witness.
 100 #[derive(Clone, PartialEq)]
 101 pub(crate) struct RevokedHTLCOutput {
 102         per_commitment_point: PublicKey,
 103         counterparty_delayed_payment_base_key: PublicKey,
 104         counterparty_htlc_base_key: PublicKey,
 105         per_commitment_key: SecretKey,
 106         weight: u64,
 107         amount: u64,
 108         htlc: HTLCOutputInCommitment,
 109 }
 110
 111 impl RevokedHTLCOutput {
 112         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 {
 113                 let weight = if htlc.offered { WEIGHT_REVOKED_OFFERED_HTLC } else { WEIGHT_REVOKED_RECEIVED_HTLC };
 114                 RevokedHTLCOutput {
 115                         per_commitment_point,
 116                         counterparty_delayed_payment_base_key,
 117                         counterparty_htlc_base_key,
 118                         per_commitment_key,
 119                         weight,
 120                         amount,
 121                         htlc
 122                 }
 123         }
 124 }
 125
 126 impl_writeable!(RevokedHTLCOutput, 33*3 + 32 + 8 + 8 + HTLC_OUTPUT_IN_COMMITMENT_SIZE, {
 127         per_commitment_point,
 128         counterparty_delayed_payment_base_key,
 129         counterparty_htlc_base_key,
 130         per_commitment_key,
 131         weight,
 132         amount,
 133         htlc
 134 });
 135
 136 /// A struct to describe a HTLC output on a counterparty commitment transaction.
 137 ///
 138 /// HTLCOutputInCommitment (hash, timelock, directon) and pubkeys are used to generate a suitable
 139 /// witnessScript.
 140 ///
 141 /// The preimage is used as part of the witness.
 142 #[derive(Clone, PartialEq)]
 143 pub(crate) struct CounterpartyOfferedHTLCOutput {
 144         per_commitment_point: PublicKey,
 145         counterparty_delayed_payment_base_key: PublicKey,
 146         counterparty_htlc_base_key: PublicKey,
 147         preimage: PaymentPreimage,
 148         htlc: HTLCOutputInCommitment
 149 }
 150
 151 impl CounterpartyOfferedHTLCOutput {
 152         pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: PublicKey, counterparty_htlc_base_key: PublicKey, preimage: PaymentPreimage, htlc: HTLCOutputInCommitment) -> Self {
 153                 CounterpartyOfferedHTLCOutput {
 154                         per_commitment_point,
 155                         counterparty_delayed_payment_base_key,
 156                         counterparty_htlc_base_key,
 157                         preimage,
 158                         htlc
 159                 }
 160         }
 161 }
 162
 163 impl_writeable!(CounterpartyOfferedHTLCOutput, 33*3 + 32 + HTLC_OUTPUT_IN_COMMITMENT_SIZE, {
 164         per_commitment_point,
 165         counterparty_delayed_payment_base_key,
 166         counterparty_htlc_base_key,
 167         preimage,
 168         htlc
 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 #[derive(Clone, PartialEq)]
 176 pub(crate) struct CounterpartyReceivedHTLCOutput {
 177         per_commitment_point: PublicKey,
 178         counterparty_delayed_payment_base_key: PublicKey,
 179         counterparty_htlc_base_key: PublicKey,
 180         htlc: HTLCOutputInCommitment
 181 }
 182
 183 impl CounterpartyReceivedHTLCOutput {
 184         pub(crate) fn build(per_commitment_point: PublicKey, counterparty_delayed_payment_base_key: PublicKey, counterparty_htlc_base_key: PublicKey, htlc: HTLCOutputInCommitment) -> Self {
 185                 CounterpartyReceivedHTLCOutput {
 186                         per_commitment_point,
 187                         counterparty_delayed_payment_base_key,
 188                         counterparty_htlc_base_key,
 189                         htlc
 190                 }
 191         }
 192 }
 193
 194 impl_writeable!(CounterpartyReceivedHTLCOutput, 33*3 + HTLC_OUTPUT_IN_COMMITMENT_SIZE, {
 195         per_commitment_point,
 196         counterparty_delayed_payment_base_key,
 197         counterparty_htlc_base_key,
 198         htlc
 199 });
 200
 201 /// A struct to describe a HTLC output on holder commitment transaction.
 202 ///
 203 /// Either offered or received, the amount is always used as part of the bip143 sighash.
 204 /// Preimage is only included as part of the witness in former case.
 205 #[derive(Clone, PartialEq)]
 206 pub(crate) struct HolderHTLCOutput {
 207         preimage: Option<PaymentPreimage>,
 208         amount: u64,
 209 }
 210
 211 impl HolderHTLCOutput {
 212         pub(crate) fn build(preimage: Option<PaymentPreimage>, amount: u64) -> Self {
 213                 HolderHTLCOutput {
 214                         preimage,
 215                         amount
 216                 }
 217         }
 218 }
 219
 220 impl_writeable!(HolderHTLCOutput, 0, {
 221         preimage,
 222         amount
 223 });
 224
 225 /// A struct to describe the channel output on the funding transaction.
 226 ///
 227 /// witnessScript is used as part of the witness redeeming the funding utxo.
 228 #[derive(Clone, PartialEq)]
 229 pub(crate) struct HolderFundingOutput {
 230         funding_redeemscript: Script,
 231 }
 232
 233 impl HolderFundingOutput {
 234         pub(crate) fn build(funding_redeemscript: Script) -> Self {
 235                 HolderFundingOutput {
 236                         funding_redeemscript,
 237                 }
 238         }
 239 }
 240
 241 impl_writeable!(HolderFundingOutput, 0, {
 242         funding_redeemscript
 243 });
 244
 245 /// A wrapper encapsulating all in-protocol differing outputs types.
 246 ///
 247 /// The generic API offers access to an outputs common attributes or allow transformation such as
 248 /// finalizing an input claiming the output.
 249 #[derive(Clone, PartialEq)]
 250 pub(crate) enum PackageSolvingData {
 251         RevokedOutput(RevokedOutput),
 252         RevokedHTLCOutput(RevokedHTLCOutput),
 253         CounterpartyOfferedHTLCOutput(CounterpartyOfferedHTLCOutput),
 254         CounterpartyReceivedHTLCOutput(CounterpartyReceivedHTLCOutput),
 255         HolderHTLCOutput(HolderHTLCOutput),
 256         HolderFundingOutput(HolderFundingOutput),
 257 }
 258
 259 impl PackageSolvingData {
 260         fn amount(&self) -> u64 {
 261                 let amt = match self {
 262                         PackageSolvingData::RevokedOutput(ref outp) => { outp.amount },
 263                         PackageSolvingData::RevokedHTLCOutput(ref outp) => { outp.amount },
 264                         PackageSolvingData::CounterpartyOfferedHTLCOutput(ref outp) => { outp.htlc.amount_msat / 1000 },
 265                         PackageSolvingData::CounterpartyReceivedHTLCOutput(ref outp) => { outp.htlc.amount_msat / 1000 },
 266                         // Note: Currently, amounts of holder outputs spending witnesses aren't used
 267                         // as we can't malleate spending package to increase their feerate. This
 268                         // should change with the remaining anchor output patchset.
 269                         PackageSolvingData::HolderHTLCOutput(..) => { 0 },
 270                         PackageSolvingData::HolderFundingOutput(..) => { 0 },
 271                 };
 272                 amt
 273         }
 274         fn weight(&self) -> usize {
 275                 let weight = match self {
 276                         PackageSolvingData::RevokedOutput(ref outp) => { outp.weight as usize },
 277                         PackageSolvingData::RevokedHTLCOutput(ref outp) => { outp.weight as usize },
 278                         PackageSolvingData::CounterpartyOfferedHTLCOutput(..) => { WEIGHT_OFFERED_HTLC as usize },
 279                         PackageSolvingData::CounterpartyReceivedHTLCOutput(..) => { WEIGHT_RECEIVED_HTLC as usize },
 280                         // Note: Currently, weights of holder outputs spending witnesses aren't used
 281                         // as we can't malleate spending package to increase their feerate. This
 282                         // should change with the remaining anchor output patchset.
 283                         PackageSolvingData::HolderHTLCOutput(..) => { debug_assert!(false); 0 },
 284                         PackageSolvingData::HolderFundingOutput(..) => { debug_assert!(false); 0 },
 285                 };
 286                 weight
 287         }
 288         fn is_compatible(&self, input: &PackageSolvingData) -> bool {
 289                 match self {
 290                         PackageSolvingData::RevokedOutput(..) => {
 291                                 match input {
 292                                         PackageSolvingData::RevokedHTLCOutput(..) => { true },
 293                                         PackageSolvingData::RevokedOutput(..) => { true },
 294                                         _ => { false }
 295                                 }
 296                         },
 297                         PackageSolvingData::RevokedHTLCOutput(..) => {
 298                                 match input {
 299                                         PackageSolvingData::RevokedOutput(..) => { true },
 300                                         PackageSolvingData::RevokedHTLCOutput(..) => { true },
 301                                         _ => { false }
 302                                 }
 303                         },
 304                         _ => { mem::discriminant(self) == mem::discriminant(&input) }
 305                 }
 306         }
 307         fn finalize_input<Signer: Sign>(&self, bumped_tx: &mut Transaction, i: usize, onchain_handler: &mut OnchainTxHandler<Signer>) -> bool {
 308                 match self {
 309                         PackageSolvingData::RevokedOutput(ref outp) => {
 310                                 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) {
 311                                         let witness_script = chan_utils::get_revokeable_redeemscript(&chan_keys.revocation_key, outp.on_counterparty_tx_csv, &chan_keys.broadcaster_delayed_payment_key);
 312                                         //TODO: should we panic on signer failure ?
 313                                         if let Ok(sig) = onchain_handler.signer.sign_justice_revoked_output(&bumped_tx, i, outp.amount, &outp.per_commitment_key, &onchain_handler.secp_ctx) {
 314                                                 bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
 315                                                 bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
 316                                                 bumped_tx.input[i].witness.push(vec!(1));
 317                                                 bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
 318                                         } else { return false; }
 319                                 }
 320                         },
 321                         PackageSolvingData::RevokedHTLCOutput(ref outp) => {
 322                                 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) {
 323                                         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);
 324                                         //TODO: should we panic on signer failure ?
 325                                         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) {
 326                                                 bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
 327                                                 bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
 328                                                 bumped_tx.input[i].witness.push(chan_keys.revocation_key.clone().serialize().to_vec());
 329                                                 bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
 330                                         } else { return false; }
 331                                 }
 332                         },
 333                         PackageSolvingData::CounterpartyOfferedHTLCOutput(ref outp) => {
 334                                 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) {
 335                                         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);
 336
 337                                         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) {
 338                                                 bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
 339                                                 bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
 340                                                 bumped_tx.input[i].witness.push(outp.preimage.0.to_vec());
 341                                                 bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
 342                                         }
 343                                 }
 344                         },
 345                         PackageSolvingData::CounterpartyReceivedHTLCOutput(ref outp) => {
 346                                 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) {
 347                                         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);
 348
 349                                         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
 350                                         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) {
 351                                                 bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
 352                                                 bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
 353                                                 // Due to BIP146 (MINIMALIF) this must be a zero-length element to relay.
 354                                                 bumped_tx.input[i].witness.push(vec![]);
 355                                                 bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
 356                                         }
 357                                 }
 358                         },
 359                         _ => { panic!("API Error!"); }
 360                 }
 361                 true
 362         }
 363         fn get_finalized_tx<Signer: Sign>(&self, outpoint: &BitcoinOutPoint, onchain_handler: &mut OnchainTxHandler<Signer>) -> Option<Transaction> {
 364                 match self {
 365                         PackageSolvingData::HolderHTLCOutput(ref outp) => { return onchain_handler.get_fully_signed_htlc_tx(outpoint, &outp.preimage); }
 366                         PackageSolvingData::HolderFundingOutput(ref outp) => { return Some(onchain_handler.get_fully_signed_holder_tx(&outp.funding_redeemscript)); }
 367                         _ => { panic!("API Error!"); }
 368                 }
 369         }
 370 }
 371
 372 impl Writeable for PackageSolvingData {
 373         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
 374                 match self {
 375                         PackageSolvingData::RevokedOutput(ref revoked_outp) => {
 376                                 0u8.write(writer)?;
 377                                 revoked_outp.write(writer)?;
 378                         },
 379                         PackageSolvingData::RevokedHTLCOutput(ref revoked_outp) => {
 380                                 1u8.write(writer)?;
 381                                 revoked_outp.write(writer)?;
 382                         },
 383                         PackageSolvingData::CounterpartyOfferedHTLCOutput(ref counterparty_outp) => {
 384                                 2u8.write(writer)?;
 385                                 counterparty_outp.write(writer)?;
 386                         },
 387                         PackageSolvingData::CounterpartyReceivedHTLCOutput(ref counterparty_outp) => {
 388                                 3u8.write(writer)?;
 389                                 counterparty_outp.write(writer)?;
 390                         },
 391                         PackageSolvingData::HolderHTLCOutput(ref holder_outp) => {
 392                                 4u8.write(writer)?;
 393                                 holder_outp.write(writer)?;
 394                         },
 395                         PackageSolvingData::HolderFundingOutput(ref funding_outp) => {
 396                                 5u8.write(writer)?;
 397                                 funding_outp.write(writer)?;
 398                         }
 399                 }
 400                 Ok(())
 401         }
 402 }
 403
 404 impl Readable for PackageSolvingData {
 405         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 406                 let byte = <u8 as Readable>::read(reader)?;
 407                 let solving_data = match byte {
 408                         0 => {
 409                                 PackageSolvingData::RevokedOutput(Readable::read(reader)?)
 410                         },
 411                         1 => {
 412                                 PackageSolvingData::RevokedHTLCOutput(Readable::read(reader)?)
 413                         },
 414                         2 => {
 415                                 PackageSolvingData::CounterpartyOfferedHTLCOutput(Readable::read(reader)?)
 416                         },
 417                         3 => {
 418                                 PackageSolvingData::CounterpartyReceivedHTLCOutput(Readable::read(reader)?)
 419                         },
 420                         4 => {
 421                                 PackageSolvingData::HolderHTLCOutput(Readable::read(reader)?)
 422                         },
 423                         5 => {
 424                                 PackageSolvingData::HolderFundingOutput(Readable::read(reader)?)
 425                         }
 426                         _ => return Err(DecodeError::UnknownVersion)
 427                 };
 428                 Ok(solving_data)
 429         }
 430 }
 431
 432 /// A malleable package might be aggregated with other packages to save on fees.
 433 /// A untractable package has been counter-signed and aggregable will break cached counterparty
 434 /// signatures.
 435 #[derive(Clone, PartialEq)]
 436 pub(crate) enum PackageMalleability {
 437         Malleable,
 438         Untractable,
 439 }
 440
 441 /// A structure to describe a package content that is generated by ChannelMonitor and
 442 /// used by OnchainTxHandler to generate and broadcast transactions settling onchain claims.
 443 ///
 444 /// A package is defined as one or more transactions claiming onchain outputs in reaction
 445 /// to confirmation of a channel transaction. Those packages might be aggregated to save on
 446 /// fees, if satisfaction of outputs's witnessScript let's us do so.
 447 ///
 448 /// As packages are time-sensitive, we fee-bump and rebroadcast them at scheduled intervals.
 449 /// Failing to confirm a package translate as a loss of funds for the user.
 450 #[derive(Clone, PartialEq)]
 451 pub struct PackageTemplate {
 452         // List of onchain outputs and solving data to generate satisfying witnesses.
 453         inputs: Vec<(BitcoinOutPoint, PackageSolvingData)>,
 454         // Packages are deemed as malleable if we have local knwoledge of at least one set of
 455         // private keys yielding a satisfying witnesses. Malleability implies that we can aggregate
 456         // packages among them to save on fees or rely on RBF to bump their feerates.
 457         // Untractable packages have been counter-signed and thus imply that we can't aggregate
 458         // them without breaking signatures. Fee-bumping strategy will also rely on CPFP.
 459         malleability: PackageMalleability,
 460         // Block height after which the earlier-output belonging to this package is mature for a
 461         // competing claim by the counterparty. As our chain tip becomes nearer from the timelock,
 462         // the fee-bumping frequency will increase. See `OnchainTxHandler::get_height_timer`.
 463         soonest_conf_deadline: u32,
 464         // Determines if this package can be aggregated.
 465         // Timelocked outputs belonging to the same transaction might have differing
 466         // satisfying heights. Picking up the later height among the output set would be a valid
 467         // aggregable strategy but it comes with at least 2 trade-offs :
 468         // * earlier-output fund are going to take longer to come back
 469         // * CLTV delta backing up a corresponding HTLC on an upstream channel could be swallowed
 470         // by the requirement of the later-output part of the set
 471         // For now, we mark such timelocked outputs as non-aggregable, though we might introduce
 472         // smarter aggregable strategy in the future.
 473         aggregable: bool,
 474         // Cache of package feerate committed at previous (re)broadcast. If bumping resources
 475         // (either claimed output value or external utxo), it will keep increasing until holder
 476         // or counterparty successful claim.
 477         feerate_previous: u64,
 478         // Cache of next height at which fee-bumping and rebroadcast will be attempted. In
 479         // the future, we might abstract it to an observed mempool fluctuation.
 480         height_timer: Option<u32>,
 481         // Confirmation height of the claimed outputs set transaction. In case of reorg reaching
 482         // it, we wipe out and forget the package.
 483         height_original: u32,
 484 }
 485
 486 impl PackageTemplate {
 487         pub(crate) fn is_malleable(&self) -> bool {
 488                 self.malleability == PackageMalleability::Malleable
 489         }
 490         pub(crate) fn timelock(&self) -> u32 {
 491                 self.soonest_conf_deadline
 492         }
 493         pub(crate) fn aggregable(&self) -> bool {
 494                 self.aggregable
 495         }
 496         pub(crate) fn feerate(&self) -> u64 {
 497                 self.feerate_previous
 498         }
 499         pub(crate) fn set_feerate(&mut self, new_feerate: u64) {
 500                 self.feerate_previous = new_feerate;
 501         }
 502         pub(crate) fn timer(&self) -> Option<u32> {
 503                 if let Some(ref timer) = self.height_timer {
 504                         return Some(*timer);
 505                 }
 506                 None
 507         }
 508         pub(crate) fn set_timer(&mut self, new_timer: Option<u32>) {
 509                 self.height_timer = new_timer;
 510         }
 511         pub(crate) fn outpoints(&self) -> Vec<&BitcoinOutPoint> {
 512                 self.inputs.iter().map(|(o, _)| o).collect()
 513         }
 514         pub(crate) fn split_package(&mut self, split_outp: &BitcoinOutPoint) -> Option<PackageTemplate> {
 515                 match self.malleability {
 516                         PackageMalleability::Malleable => {
 517                                 let mut split_package = None;
 518                                 let timelock = self.soonest_conf_deadline;
 519                                 let aggregable = self.aggregable;
 520                                 let feerate_previous = self.feerate_previous;
 521                                 let height_timer = self.height_timer;
 522                                 let height_original = self.height_original;
 523                                 self.inputs.retain(|outp| {
 524                                         if *split_outp == outp.0 {
 525                                                 split_package = Some(PackageTemplate {
 526                                                         inputs: vec![(outp.0, outp.1.clone())],
 527                                                         malleability: PackageMalleability::Malleable,
 528                                                         soonest_conf_deadline: timelock,
 529                                                         aggregable,
 530                                                         feerate_previous,
 531                                                         height_timer,
 532                                                         height_original,
 533                                                 });
 534                                                 return false;
 535                                         }
 536                                         return true;
 537                                 });
 538                                 return split_package;
 539                         },
 540                         _ => {
 541                                 // Note, we may try to split on remote transaction for
 542                                 // which we don't have a competing one (HTLC-Success before
 543                                 // timelock expiration). This explain we don't panic!
 544                                 // We should refactor OnchainTxHandler::block_connected to
 545                                 // only test equality on competing claims.
 546                                 return None;
 547                         }
 548                 }
 549         }
 550         pub(crate) fn merge_package(&mut self, mut merge_from: PackageTemplate) {
 551                 assert_eq!(self.height_original, merge_from.height_original);
 552                 if self.malleability == PackageMalleability::Untractable || merge_from.malleability == PackageMalleability::Untractable {
 553                         panic!("Merging template on untractable packages");
 554                 }
 555                 if !self.aggregable || !merge_from.aggregable {
 556                         panic!("Merging non aggregatable packages");
 557                 }
 558                 if let Some((_, lead_input)) = self.inputs.first() {
 559                         for (_, v) in merge_from.inputs.iter() {
 560                                 if !lead_input.is_compatible(v) { panic!("Merging outputs from differing types !"); }
 561                         }
 562                 } else { panic!("Merging template on an empty package"); }
 563                 for (k, v) in merge_from.inputs.drain(..) {
 564                         self.inputs.push((k, v));
 565                 }
 566                 //TODO: verify coverage and sanity?
 567                 if self.soonest_conf_deadline > merge_from.soonest_conf_deadline {
 568                         self.soonest_conf_deadline = merge_from.soonest_conf_deadline;
 569                 }
 570                 if self.feerate_previous > merge_from.feerate_previous {
 571                         self.feerate_previous = merge_from.feerate_previous;
 572                 }
 573                 self.height_timer = cmp::min(self.height_timer, merge_from.height_timer);
 574         }
 575         pub(crate) fn package_amount(&self) -> u64 {
 576                 let mut amounts = 0;
 577                 for (_, outp) in self.inputs.iter() {
 578                         amounts += outp.amount();
 579                 }
 580                 amounts
 581         }
 582         pub(crate) fn package_weight(&self, destination_script: &Script) -> usize {
 583                 let mut inputs_weight = 0;
 584                 let mut witnesses_weight = 2; // count segwit flags
 585                 for (_, outp) in self.inputs.iter() {
 586                         // previous_out_point: 36 bytes ; var_int: 1 byte ; sequence: 4 bytes
 587                         inputs_weight += 41 * WITNESS_SCALE_FACTOR;
 588                         witnesses_weight += outp.weight();
 589                 }
 590                 // version: 4 bytes ; count_tx_in: 1 byte ; count_tx_out: 1 byte ; lock_time: 4 bytes
 591                 let transaction_weight = 10 * WITNESS_SCALE_FACTOR;
 592                 // value: 8 bytes ; var_int: 1 byte ; pk_script: `destination_script.len()`
 593                 let output_weight = (8 + 1 + destination_script.len()) * WITNESS_SCALE_FACTOR;
 594                 inputs_weight + witnesses_weight + transaction_weight + output_weight
 595         }
 596         pub(crate) fn finalize_package<L: Deref, Signer: Sign>(&self, onchain_handler: &mut OnchainTxHandler<Signer>, value: u64, destination_script: Script, logger: &L) -> Option<Transaction>
 597                 where L::Target: Logger,
 598         {
 599                 match self.malleability {
 600                         PackageMalleability::Malleable => {
 601                                 let mut bumped_tx = Transaction {
 602                                         version: 2,
 603                                         lock_time: 0,
 604                                         input: vec![],
 605                                         output: vec![TxOut {
 606                                                 script_pubkey: destination_script,
 607                                                 value,
 608                                         }],
 609                                 };
 610                                 for (outpoint, _) in self.inputs.iter() {
 611                                         bumped_tx.input.push(TxIn {
 612                                                 previous_output: *outpoint,
 613                                                 script_sig: Script::new(),
 614                                                 sequence: 0xfffffffd,
 615                                                 witness: Vec::new(),
 616                                         });
 617                                 }
 618                                 for (i, (outpoint, out)) in self.inputs.iter().enumerate() {
 619                                         log_trace!(logger, "Adding claiming input for outpoint {}:{}", outpoint.txid, outpoint.vout);
 620                                         if !out.finalize_input(&mut bumped_tx, i, onchain_handler) { return None; }
 621                                 }
 622                                 log_trace!(logger, "Finalized transaction {} ready to broadcast", bumped_tx.txid());
 623                                 return Some(bumped_tx);
 624                         },
 625                         PackageMalleability::Untractable => {
 626                                 if let Some((outpoint, outp)) = self.inputs.first() {
 627                                         if let Some(final_tx) = outp.get_finalized_tx(outpoint, onchain_handler) {
 628                                                 log_trace!(logger, "Adding claiming input for outpoint {}:{}", outpoint.txid, outpoint.vout);
 629                                                 log_trace!(logger, "Finalized transaction {} ready to broadcast", final_tx.txid());
 630                                                 return Some(final_tx);
 631                                         }
 632                                         return None;
 633                                 } else { panic!("API Error: Package must not be inputs empty"); }
 634                         },
 635                 }
 636         }
 637         pub (crate) fn build_package(txid: Txid, vout: u32, input_solving_data: PackageSolvingData, soonest_conf_deadline: u32, aggregable: bool, height_original: u32) -> Self {
 638                 let malleability = match input_solving_data {
 639                         PackageSolvingData::RevokedOutput(..) => { PackageMalleability::Malleable },
 640                         PackageSolvingData::RevokedHTLCOutput(..) => { PackageMalleability::Malleable },
 641                         PackageSolvingData::CounterpartyOfferedHTLCOutput(..) => { PackageMalleability::Malleable },
 642                         PackageSolvingData::CounterpartyReceivedHTLCOutput(..) => { PackageMalleability::Malleable },
 643                         PackageSolvingData::HolderHTLCOutput(..) => { PackageMalleability::Untractable },
 644                         PackageSolvingData::HolderFundingOutput(..) => { PackageMalleability::Untractable },
 645                 };
 646                 let mut inputs = Vec::with_capacity(1);
 647                 inputs.push((BitcoinOutPoint { txid, vout }, input_solving_data));
 648                 PackageTemplate {
 649                         inputs,
 650                         malleability,
 651                         soonest_conf_deadline,
 652                         aggregable,
 653                         feerate_previous: 0,
 654                         height_timer: None,
 655                         height_original,
 656                 }
 657         }
 658 }
 659
 660 impl Writeable for PackageTemplate {
 661         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
 662                 writer.write_all(&byte_utils::be64_to_array(self.inputs.len() as u64))?;
 663                 for (ref outpoint, ref rev_outp) in self.inputs.iter() {
 664                         outpoint.write(writer)?;
 665                         rev_outp.write(writer)?;
 666                 }
 667                 self.soonest_conf_deadline.write(writer)?;
 668                 self.feerate_previous.write(writer)?;
 669                 self.height_timer.write(writer)?;
 670                 self.height_original.write(writer)?;
 671                 Ok(())
 672         }
 673 }
 674
 675 impl Readable for PackageTemplate {
 676         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 677                 let inputs_count = <u64 as Readable>::read(reader)?;
 678                 let mut inputs: Vec<(BitcoinOutPoint, PackageSolvingData)> = Vec::with_capacity(cmp::min(inputs_count as usize, MAX_ALLOC_SIZE / 128));
 679                 for _ in 0..inputs_count {
 680                         let outpoint = Readable::read(reader)?;
 681                         let rev_outp = Readable::read(reader)?;
 682                         inputs.push((outpoint, rev_outp));
 683                 }
 684                 let (malleability, aggregable) = if let Some((_, lead_input)) = inputs.first() {
 685                         match lead_input {
 686                                 PackageSolvingData::RevokedOutput(..) => { (PackageMalleability::Malleable, true) },
 687                                 PackageSolvingData::RevokedHTLCOutput(..) => { (PackageMalleability::Malleable, true) },
 688                                 PackageSolvingData::CounterpartyOfferedHTLCOutput(..) => { (PackageMalleability::Malleable, true) },
 689                                 PackageSolvingData::CounterpartyReceivedHTLCOutput(..) => { (PackageMalleability::Malleable, false) },
 690                                 PackageSolvingData::HolderHTLCOutput(..) => { (PackageMalleability::Untractable, false) },
 691                                 PackageSolvingData::HolderFundingOutput(..) => { (PackageMalleability::Untractable, false) },
 692                         }
 693                 } else { return Err(DecodeError::InvalidValue); };
 694                 let soonest_conf_deadline = Readable::read(reader)?;
 695                 let feerate_previous = Readable::read(reader)?;
 696                 let height_timer = Readable::read(reader)?;
 697                 let height_original = Readable::read(reader)?;
 698                 Ok(PackageTemplate {
 699                         inputs,
 700                         malleability,
 701                         soonest_conf_deadline,
 702                         aggregable,
 703                         feerate_previous,
 704                         height_timer,
 705                         height_original,
 706                 })
 707         }
 708 }
 709
 710 /// Utilities for computing witnesses weight and feerate computation for onchain operation
 711 #[derive(PartialEq, Clone, Copy)]
 712 pub(crate) enum InputDescriptors {
 713         RevokedOfferedHTLC,
 714         RevokedReceivedHTLC,
 715         OfferedHTLC,
 716         ReceivedHTLC,
 717         RevokedOutput, // either a revoked to_holder output on commitment tx, a revoked HTLC-Timeout output or a revoked HTLC-Success output
 718 }
 719
 720 impl Writeable for InputDescriptors {
 721         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
 722                 match self {
 723                         &InputDescriptors::RevokedOfferedHTLC => {
 724                                 writer.write_all(&[0; 1])?;
 725                         },
 726                         &InputDescriptors::RevokedReceivedHTLC => {
 727                                 writer.write_all(&[1; 1])?;
 728                         },
 729                         &InputDescriptors::OfferedHTLC => {
 730                                 writer.write_all(&[2; 1])?;
 731                         },
 732                         &InputDescriptors::ReceivedHTLC => {
 733                                 writer.write_all(&[3; 1])?;
 734                         }
 735                         &InputDescriptors::RevokedOutput => {
 736                                 writer.write_all(&[4; 1])?;
 737                         }
 738                 }
 739                 Ok(())
 740         }
 741 }
 742
 743 impl Readable for InputDescriptors {
 744         fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 745                 let input_descriptor = match <u8 as Readable>::read(reader)? {
 746                         0 => {
 747                                 InputDescriptors::RevokedOfferedHTLC
 748                         },
 749                         1 => {
 750                                 InputDescriptors::RevokedReceivedHTLC
 751                         },
 752                         2 => {
 753                                 InputDescriptors::OfferedHTLC
 754                         },
 755                         3 => {
 756                                 InputDescriptors::ReceivedHTLC
 757                         },
 758                         4 => {
 759                                 InputDescriptors::RevokedOutput
 760                         }
 761                         _ => return Err(DecodeError::InvalidValue),
 762                 };
 763                 Ok(input_descriptor)
 764         }
 765 }
 766
 767 pub(crate) fn get_witnesses_weight(inputs: &[InputDescriptors]) -> usize {
 768         let mut tx_weight = 2; // count segwit flags
 769         for inp in inputs {
 770                 // We use expected weight (and not actual) as signatures and time lock delays may vary
 771                 tx_weight +=  match inp {
 772                         // number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
 773                         &InputDescriptors::RevokedOfferedHTLC => {
 774                                 1 + 1 + 73 + 1 + 33 + 1 + 133
 775                         },
 776                         // number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
 777                         &InputDescriptors::RevokedReceivedHTLC => {
 778                                 1 + 1 + 73 + 1 + 33 + 1 + 139
 779                         },
 780                         // number_of_witness_elements + sig_length + counterpartyhtlc_sig  + preimage_length + preimage + witness_script_length + witness_script
 781                         &InputDescriptors::OfferedHTLC => {
 782                                 1 + 1 + 73 + 1 + 32 + 1 + 133
 783                         },
 784                         // number_of_witness_elements + sig_length + revocation_sig + pubkey_length + revocationpubkey + witness_script_length + witness_script
 785                         &InputDescriptors::ReceivedHTLC => {
 786                                 1 + 1 + 73 + 1 + 1 + 1 + 139
 787                         },
 788                         // number_of_witness_elements + sig_length + revocation_sig + true_length + op_true + witness_script_length + witness_script
 789                         &InputDescriptors::RevokedOutput => {
 790                                 1 + 1 + 73 + 1 + 1 + 1 + 77
 791                         },
 792                 };
 793         }
 794         tx_weight
 795 }
 796
 797 /// Attempt to propose a bumping fee for a transaction from its spent output's values and predicted
 798 /// weight. We start with the highest priority feerate returned by the node's fee estimator then
 799 /// fall-back to lower priorities until we have enough value available to suck from.
 800 ///
 801 /// If the proposed fee is less than the available spent output's values, we return the proposed
 802 /// fee and the corresponding updated feerate. If the proposed fee is equal or more than the
 803 /// available spent output's values, we return nothing
 804 fn compute_fee_from_spent_amounts<F: Deref, L: Deref>(input_amounts: u64, predicted_weight: usize, fee_estimator: &F, logger: &L) -> Option<(u64, u64)>
 805         where F::Target: FeeEstimator,
 806               L::Target: Logger,
 807 {
 808         let mut updated_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) as u64;
 809         let mut fee = updated_feerate * (predicted_weight as u64) / 1000;
 810         if input_amounts <= fee {
 811                 updated_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Normal) as u64;
 812                 fee = updated_feerate * (predicted_weight as u64) / 1000;
 813                 if input_amounts <= fee {
 814                         updated_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background) as u64;
 815                         fee = updated_feerate * (predicted_weight as u64) / 1000;
 816                         if input_amounts <= fee {
 817                                 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)",
 818                                         fee, input_amounts);
 819                                 None
 820                         } else {
 821                                 log_warn!(logger, "Used low priority fee for on-chain punishment tx as high priority fee was more than the entire claim balance ({} sat)",
 822                                         input_amounts);
 823                                 Some((fee, updated_feerate))
 824                         }
 825                 } else {
 826                         log_warn!(logger, "Used medium priority fee for on-chain punishment tx as high priority fee was more than the entire claim balance ({} sat)",
 827                                 input_amounts);
 828                         Some((fee, updated_feerate))
 829                 }
 830         } else {
 831                 Some((fee, updated_feerate))
 832         }
 833 }
 834
 835 /// Attempt to propose a bumping fee for a transaction from its spent output's values and predicted
 836 /// weight. If feerates proposed by the fee-estimator have been increasing since last fee-bumping
 837 /// attempt, use them. Otherwise, blindly bump the feerate by 25% of the previous feerate. We also
 838 /// verify that those bumping heuristics respect BIP125 rules 3) and 4) and if required adjust
 839 /// the new fee to meet the RBF policy requirement.
 840 fn feerate_bump<F: Deref, L: Deref>(predicted_weight: usize, input_amounts: u64, previous_feerate: u64, fee_estimator: &F, logger: &L) -> Option<(u64, u64)>
 841         where F::Target: FeeEstimator,
 842               L::Target: Logger,
 843 {
 844         // If old feerate inferior to actual one given back by Fee Estimator, use it to compute new fee...
 845         let new_fee = if let Some((new_fee, _)) = compute_fee_from_spent_amounts(input_amounts, predicted_weight, fee_estimator, logger) {
 846                 let updated_feerate = new_fee / (predicted_weight as u64 * 1000);
 847                 if updated_feerate > previous_feerate {
 848                         new_fee
 849                 } else {
 850                         // ...else just increase the previous feerate by 25% (because that's a nice number)
 851                         let new_fee = previous_feerate * (predicted_weight as u64) / 750;
 852                         if input_amounts <= new_fee {
 853                                 log_trace!(logger, "Can't 25% bump new claiming tx, amount {} is too small", input_amounts);
 854                                 return None;
 855                         }
 856                         new_fee
 857                 }
 858         } else {
 859                 log_trace!(logger, "Can't new-estimation bump new claiming tx, amount {} is too small", input_amounts);
 860                 return None;
 861         };
 862
 863         let previous_fee = previous_feerate * (predicted_weight as u64) / 1000;
 864         let min_relay_fee = MIN_RELAY_FEE_SAT_PER_1000_WEIGHT * (predicted_weight as u64) / 1000;
 865         // BIP 125 Opt-in Full Replace-by-Fee Signaling
 866         //      * 3. The replacement transaction pays an absolute fee of at least the sum paid by the original transactions.
 867         //      * 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.
 868         let new_fee = if new_fee < previous_fee + min_relay_fee {
 869                 new_fee + previous_fee + min_relay_fee - new_fee
 870         } else {
 871                 new_fee
 872         };
 873         Some((new_fee, new_fee * 1000 / (predicted_weight as u64)))
 874 }
 875
 876 /// Deduce a new proposed fee from the claiming transaction output value.
 877 /// If the new proposed fee is superior to the consumed outpoint's value, burn everything in miner's
 878 /// fee to deter counterparties attacker.
 879 pub(crate) fn compute_output_value<F: Deref, L: Deref>(predicted_weight: usize, input_amounts: u64, previous_feerate: u64, fee_estimator: &F, logger: &L) -> Option<(u64, u64)>
 880         where F::Target: FeeEstimator,
 881               L::Target: Logger,
 882 {
 883         // If old feerate is 0, first iteration of this claim, use normal fee calculation
 884         if previous_feerate != 0 {
 885                 if let Some((new_fee, feerate)) = feerate_bump(predicted_weight, input_amounts, previous_feerate, fee_estimator, logger) {
 886                         // If new computed fee is superior at the whole claimable amount burn all in fees
 887                         if new_fee > input_amounts {
 888                                 return Some((0, feerate));
 889                         } else {
 890                                 return Some((input_amounts - new_fee, feerate));
 891                         }
 892                 }
 893         } else {
 894                 if let Some((new_fee, feerate)) = compute_fee_from_spent_amounts(input_amounts, predicted_weight, fee_estimator, logger) {
 895                                 return Some((input_amounts - new_fee, feerate));
 896                 }
 897         }
 898         None
 899 }