-#[cfg(anchors)]
-/// A descriptor used to sign for a commitment transaction's anchor output.
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct AnchorDescriptor {
- /// A unique identifier used along with `channel_value_satoshis` to re-derive the
- /// [`InMemorySigner`] required to sign `input`.
- ///
- /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
- pub channel_keys_id: [u8; 32],
- /// The value in satoshis of the channel we're attempting to spend the anchor output of. This is
- /// used along with `channel_keys_id` to re-derive the [`InMemorySigner`] required to sign
- /// `input`.
- ///
- /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
- pub channel_value_satoshis: u64,
- /// The transaction input's outpoint corresponding to the commitment transaction's anchor
- /// output.
- pub outpoint: OutPoint,
-}
-
-#[cfg(anchors)]
-/// A descriptor used to sign for a commitment transaction's HTLC output.
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct HTLCDescriptor {
- /// A unique identifier used along with `channel_value_satoshis` to re-derive the
- /// [`InMemorySigner`] required to sign `input`.
- ///
- /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
- pub channel_keys_id: [u8; 32],
- /// The value in satoshis of the channel we're attempting to spend the anchor output of. This is
- /// used along with `channel_keys_id` to re-derive the [`InMemorySigner`] required to sign
- /// `input`.
- ///
- /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
- pub channel_value_satoshis: u64,
- /// The necessary channel parameters that need to be provided to the re-derived
- /// [`InMemorySigner`] through [`ChannelSigner::provide_channel_parameters`].
- ///
- /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
- /// [`ChannelSigner::provide_channel_parameters`]: crate::chain::keysinterface::ChannelSigner::provide_channel_parameters
- pub channel_parameters: ChannelTransactionParameters,
- /// The txid of the commitment transaction in which the HTLC output lives.
- pub commitment_txid: Txid,
- /// The number of the commitment transaction in which the HTLC output lives.
- pub per_commitment_number: u64,
- /// The details of the HTLC as it appears in the commitment transaction.
- pub htlc: HTLCOutputInCommitment,
- /// The preimage, if `Some`, to claim the HTLC output with. If `None`, the timeout path must be
- /// taken.
- pub preimage: Option<PaymentPreimage>,
- /// The counterparty's signature required to spend the HTLC output.
- pub counterparty_sig: Signature
-}
-
-#[cfg(anchors)]
-impl HTLCDescriptor {
- /// Returns the unsigned transaction input spending the HTLC output in the commitment
- /// transaction.
- pub fn unsigned_tx_input(&self) -> TxIn {
- chan_utils::build_htlc_input(&self.commitment_txid, &self.htlc, true /* opt_anchors */)
- }
-
- /// Returns the delayed output created as a result of spending the HTLC output in the commitment
- /// transaction.
- pub fn tx_output<C: secp256k1::Signing + secp256k1::Verification>(
- &self, per_commitment_point: &PublicKey, secp: &Secp256k1<C>
- ) -> TxOut {
- let channel_params = self.channel_parameters.as_holder_broadcastable();
- let broadcaster_keys = channel_params.broadcaster_pubkeys();
- let counterparty_keys = channel_params.countersignatory_pubkeys();
- let broadcaster_delayed_key = chan_utils::derive_public_key(
- secp, per_commitment_point, &broadcaster_keys.delayed_payment_basepoint
- );
- let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
- secp, per_commitment_point, &counterparty_keys.revocation_basepoint
- );
- chan_utils::build_htlc_output(
- 0 /* feerate_per_kw */, channel_params.contest_delay(), &self.htlc, true /* opt_anchors */,
- false /* use_non_zero_fee_anchors */, &broadcaster_delayed_key, &counterparty_revocation_key
- )
- }
-
- /// Returns the witness script of the HTLC output in the commitment transaction.
- pub fn witness_script<C: secp256k1::Signing + secp256k1::Verification>(
- &self, per_commitment_point: &PublicKey, secp: &Secp256k1<C>
- ) -> Script {
- let channel_params = self.channel_parameters.as_holder_broadcastable();
- let broadcaster_keys = channel_params.broadcaster_pubkeys();
- let counterparty_keys = channel_params.countersignatory_pubkeys();
- let broadcaster_htlc_key = chan_utils::derive_public_key(
- secp, per_commitment_point, &broadcaster_keys.htlc_basepoint
- );
- let counterparty_htlc_key = chan_utils::derive_public_key(
- secp, per_commitment_point, &counterparty_keys.htlc_basepoint
- );
- let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
- secp, per_commitment_point, &counterparty_keys.revocation_basepoint
- );
- chan_utils::get_htlc_redeemscript_with_explicit_keys(
- &self.htlc, true /* opt_anchors */, &broadcaster_htlc_key, &counterparty_htlc_key,
- &counterparty_revocation_key,
- )
- }
-
- /// Returns the fully signed witness required to spend the HTLC output in the commitment
- /// transaction.
- pub fn tx_input_witness(&self, signature: &Signature, witness_script: &Script) -> Witness {
- chan_utils::build_htlc_input_witness(
- signature, &self.counterparty_sig, &self.preimage, witness_script, true /* opt_anchors */
- )
- }
-}
-
-#[cfg(anchors)]
-/// Represents the different types of transactions, originating from LDK, to be bumped.
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum BumpTransactionEvent {
- /// Indicates that a channel featuring anchor outputs is to be closed by broadcasting the local
- /// commitment transaction. Since commitment transactions have a static feerate pre-agreed upon,
- /// they may need additional fees to be attached through a child transaction using the popular
- /// [Child-Pays-For-Parent](https://bitcoinops.org/en/topics/cpfp) fee bumping technique. This
- /// child transaction must include the anchor input described within `anchor_descriptor` along
- /// with additional inputs to meet the target feerate. Failure to meet the target feerate
- /// decreases the confirmation odds of the transaction package (which includes the commitment
- /// and child anchor transactions), possibly resulting in a loss of funds. Once the transaction
- /// is constructed, it must be fully signed for and broadcast by the consumer of the event
- /// along with the `commitment_tx` enclosed. Note that the `commitment_tx` must always be
- /// broadcast first, as the child anchor transaction depends on it.
- ///
- /// The consumer should be able to sign for any of the additional inputs included within the
- /// child anchor transaction. To sign its anchor input, an [`InMemorySigner`] should be
- /// re-derived through [`KeysManager::derive_channel_keys`] with the help of
- /// [`AnchorDescriptor::channel_keys_id`] and [`AnchorDescriptor::channel_value_satoshis`]. The
- /// anchor input signature can be computed with [`EcdsaChannelSigner::sign_holder_anchor_input`],
- /// which can then be provided to [`build_anchor_input_witness`] along with the `funding_pubkey`
- /// to obtain the full witness required to spend.
- ///
- /// It is possible to receive more than one instance of this event if a valid child anchor
- /// transaction is never broadcast or is but not with a sufficient fee to be mined. Care should
- /// be taken by the consumer of the event to ensure any future iterations of the child anchor
- /// transaction adhere to the [Replace-By-Fee
- /// rules](https://github.com/bitcoin/bitcoin/blob/master/doc/policy/mempool-replacements.md)
- /// for fee bumps to be accepted into the mempool, and eventually the chain. As the frequency of
- /// these events is not user-controlled, users may ignore/drop the event if they are no longer
- /// able to commit external confirmed funds to the child anchor transaction.
- ///
- /// The set of `pending_htlcs` on the commitment transaction to be broadcast can be inspected to
- /// determine whether a significant portion of the channel's funds are allocated to HTLCs,
- /// enabling users to make their own decisions regarding the importance of the commitment
- /// transaction's confirmation. Note that this is not required, but simply exists as an option
- /// for users to override LDK's behavior. On commitments with no HTLCs (indicated by those with
- /// an empty `pending_htlcs`), confirmation of the commitment transaction can be considered to
- /// be not urgent.
- ///
- /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
- /// [`KeysManager::derive_channel_keys`]: crate::chain::keysinterface::KeysManager::derive_channel_keys
- /// [`EcdsaChannelSigner::sign_holder_anchor_input`]: crate::chain::keysinterface::EcdsaChannelSigner::sign_holder_anchor_input
- /// [`build_anchor_input_witness`]: crate::ln::chan_utils::build_anchor_input_witness
- ChannelClose {
- /// The target feerate that the transaction package, which consists of the commitment
- /// transaction and the to-be-crafted child anchor transaction, must meet.
- package_target_feerate_sat_per_1000_weight: u32,
- /// The channel's commitment transaction to bump the fee of. This transaction should be
- /// broadcast along with the anchor transaction constructed as a result of consuming this
- /// event.
- commitment_tx: Transaction,
- /// The absolute fee in satoshis of the commitment transaction. This can be used along the
- /// with weight of the commitment transaction to determine its feerate.
- commitment_tx_fee_satoshis: u64,
- /// The descriptor to sign the anchor input of the anchor transaction constructed as a
- /// result of consuming this event.
- anchor_descriptor: AnchorDescriptor,
- /// The set of pending HTLCs on the commitment transaction that need to be resolved once the
- /// commitment transaction confirms.
- pending_htlcs: Vec<HTLCOutputInCommitment>,
- },
- /// Indicates that a channel featuring anchor outputs has unilaterally closed on-chain by a
- /// holder commitment transaction and its HTLC(s) need to be resolved on-chain. With the
- /// zero-HTLC-transaction-fee variant of anchor outputs, the pre-signed HTLC
- /// transactions have a zero fee, thus requiring additional inputs and/or outputs to be attached
- /// for a timely confirmation within the chain. These additional inputs and/or outputs must be
- /// appended to the resulting HTLC transaction to meet the target feerate. Failure to meet the
- /// target feerate decreases the confirmation odds of the transaction, possibly resulting in a
- /// loss of funds. Once the transaction meets the target feerate, it must be signed for and
- /// broadcast by the consumer of the event.
- ///
- /// The consumer should be able to sign for any of the non-HTLC inputs added to the resulting
- /// HTLC transaction. To sign HTLC inputs, an [`InMemorySigner`] should be re-derived through
- /// [`KeysManager::derive_channel_keys`] with the help of `channel_keys_id` and
- /// `channel_value_satoshis`. Each HTLC input's signature can be computed with
- /// [`EcdsaChannelSigner::sign_holder_htlc_transaction`], which can then be provided to
- /// [`HTLCDescriptor::tx_input_witness`] to obtain the fully signed witness required to spend.
- ///
- /// It is possible to receive more than one instance of this event if a valid HTLC transaction
- /// is never broadcast or is but not with a sufficient fee to be mined. Care should be taken by
- /// the consumer of the event to ensure any future iterations of the HTLC transaction adhere to
- /// the [Replace-By-Fee
- /// rules](https://github.com/bitcoin/bitcoin/blob/master/doc/policy/mempool-replacements.md)
- /// for fee bumps to be accepted into the mempool, and eventually the chain. As the frequency of
- /// these events is not user-controlled, users may ignore/drop the event if either they are no
- /// longer able to commit external confirmed funds to the HTLC transaction or the fee committed
- /// to the HTLC transaction is greater in value than the HTLCs being claimed.
- ///
- /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
- /// [`KeysManager::derive_channel_keys`]: crate::chain::keysinterface::KeysManager::derive_channel_keys
- /// [`EcdsaChannelSigner::sign_holder_htlc_transaction`]: crate::chain::keysinterface::EcdsaChannelSigner::sign_holder_htlc_transaction
- /// [`HTLCDescriptor::tx_input_witness`]: HTLCDescriptor::tx_input_witness
- HTLCResolution {
- /// The target feerate that the resulting HTLC transaction must meet.
- target_feerate_sat_per_1000_weight: u32,
- /// The set of pending HTLCs on the confirmed commitment that need to be claimed, preferably
- /// by the same transaction.
- htlc_descriptors: Vec<HTLCDescriptor>,
- },
-}
-