- SP::Target: SignerProvider<Signer = S>
- {
- let mut signer = signer_provider.derive_channel_signer(
- self.channel_derivation_parameters.value_satoshis,
- self.channel_derivation_parameters.keys_id,
- );
- signer.provide_channel_parameters(&self.channel_derivation_parameters.transaction_parameters);
- signer
- }
-}
-
-/// A descriptor used to sign for a commitment transaction's HTLC output.
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct HTLCDescriptor {
- /// The parameters required to derive the signer for the HTLC input.
- pub channel_derivation_parameters: ChannelDerivationParameters,
- /// 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 key tweak corresponding to the number of the commitment transaction in which the HTLC
- /// output lives. This tweak is applied to all the basepoints for both parties in the channel to
- /// arrive at unique keys per commitment.
- ///
- /// See <https://github.com/lightning/bolts/blob/master/03-transactions.md#keys> for more info.
- pub per_commitment_point: PublicKey,
- /// 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
-}
-
-impl HTLCDescriptor {
- /// Returns the outpoint of the HTLC output in the commitment transaction. This is the outpoint
- /// being spent by the HTLC input in the HTLC transaction.
- pub fn outpoint(&self) -> OutPoint {
- OutPoint {
- txid: self.commitment_txid,
- vout: self.htlc.transaction_output_index.unwrap(),
- }
- }
-
- /// Returns the UTXO to be spent by the HTLC input, which can be obtained via
- /// [`Self::unsigned_tx_input`].
- pub fn previous_utxo<C: secp256k1::Signing + secp256k1::Verification>(&self, secp: &Secp256k1<C>) -> TxOut {
- TxOut {
- script_pubkey: self.witness_script(secp).to_v0_p2wsh(),
- value: self.htlc.amount_msat / 1000,
- }
- }
-
- /// 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, &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies())
- }
-
- /// 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, secp: &Secp256k1<C>) -> TxOut {
- let channel_params = self.channel_derivation_parameters.transaction_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, &self.per_commitment_point, &broadcaster_keys.delayed_payment_basepoint
- );
- let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
- secp, &self.per_commitment_point, &counterparty_keys.revocation_basepoint
- );
- chan_utils::build_htlc_output(
- 0 /* feerate_per_kw */, channel_params.contest_delay(), &self.htlc,
- &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies(), &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, secp: &Secp256k1<C>) -> Script {
- let channel_params = self.channel_derivation_parameters.transaction_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, &self.per_commitment_point, &broadcaster_keys.htlc_basepoint
- );
- let counterparty_htlc_key = chan_utils::derive_public_key(
- secp, &self.per_commitment_point, &counterparty_keys.htlc_basepoint
- );
- let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
- secp, &self.per_commitment_point, &counterparty_keys.revocation_basepoint
- );
- chan_utils::get_htlc_redeemscript_with_explicit_keys(
- &self.htlc, &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies(), &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, &ChannelTypeFeatures::anchors_zero_htlc_fee_and_dependencies() /* opt_anchors */
- )
- }
-
- /// Derives the channel signer required to sign the HTLC input.
- pub fn derive_channel_signer<S: WriteableEcdsaChannelSigner, SP: Deref>(&self, signer_provider: &SP) -> S
- where
- SP::Target: SignerProvider<Signer = S>