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