Merge pull request #2868 from orbitalturtle/export-send-onion-path
[rust-lightning] / lightning / src / events / bump_transaction.rs
index 35e9da60544ddc680535983767117e9faf732afd..1b019ba349e0ae8687a190b92ebd144fe164f6f9 100644 (file)
@@ -21,20 +21,23 @@ use crate::ln::channel::ANCHOR_OUTPUT_VALUE_SATOSHI;
 use crate::ln::chan_utils;
 use crate::ln::chan_utils::{
        ANCHOR_INPUT_WITNESS_WEIGHT, HTLC_SUCCESS_INPUT_ANCHOR_WITNESS_WEIGHT,
-       HTLC_TIMEOUT_INPUT_ANCHOR_WITNESS_WEIGHT, ChannelTransactionParameters, HTLCOutputInCommitment
+       HTLC_TIMEOUT_INPUT_ANCHOR_WITNESS_WEIGHT, HTLCOutputInCommitment
 };
-use crate::ln::features::ChannelTypeFeatures;
-use crate::ln::PaymentPreimage;
 use crate::prelude::*;
-use crate::sign::{EcdsaChannelSigner, SignerProvider, WriteableEcdsaChannelSigner};
+use crate::sign::{
+       ChannelDerivationParameters, HTLCDescriptor, SignerProvider, P2WPKH_WITNESS_WEIGHT
+};
+use crate::sign::ecdsa::{EcdsaChannelSigner, WriteableEcdsaChannelSigner};
 use crate::sync::Mutex;
 use crate::util::logger::Logger;
 
-use bitcoin::{OutPoint, PackedLockTime, PubkeyHash, Sequence, Script, Transaction, Txid, TxIn, TxOut, Witness, WPubkeyHash};
+use bitcoin::{OutPoint, PubkeyHash, Sequence, ScriptBuf, Transaction, TxIn, TxOut, Witness, WPubkeyHash};
 use bitcoin::blockdata::constants::WITNESS_SCALE_FACTOR;
+use bitcoin::blockdata::locktime::absolute::LockTime;
 use bitcoin::consensus::Encodable;
+use bitcoin::psbt::PartiallySignedTransaction;
 use bitcoin::secp256k1;
-use bitcoin::secp256k1::{PublicKey, Secp256k1};
+use bitcoin::secp256k1::Secp256k1;
 use bitcoin::secp256k1::ecdsa::Signature;
 
 const EMPTY_SCRIPT_SIG_WEIGHT: u64 = 1 /* empty script_sig */ * WITNESS_SCALE_FACTOR as u64;
@@ -43,26 +46,6 @@ const BASE_INPUT_SIZE: u64 = 32 /* txid */ + 4 /* vout */ + 4 /* sequence */;
 
 const BASE_INPUT_WEIGHT: u64 = BASE_INPUT_SIZE * WITNESS_SCALE_FACTOR as u64;
 
-/// The parameters required to derive a channel signer via [`SignerProvider`].
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub struct ChannelDerivationParameters {
-       /// The value in satoshis of the channel we're attempting to spend the anchor output of.
-       pub value_satoshis: u64,
-       /// The unique identifier to re-derive the signer for the associated channel.
-       pub keys_id: [u8; 32],
-       /// The necessary channel parameters that need to be provided to the re-derived signer through
-       /// [`ChannelSigner::provide_channel_parameters`].
-       ///
-       /// [`ChannelSigner::provide_channel_parameters`]: crate::sign::ChannelSigner::provide_channel_parameters
-       pub transaction_parameters: ChannelTransactionParameters,
-}
-
-impl_writeable_tlv_based!(ChannelDerivationParameters, {
-    (0, value_satoshis, required),
-    (2, keys_id, required),
-    (4, transaction_parameters, required),
-});
-
 /// A descriptor used to sign for a commitment transaction's anchor output.
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct AnchorDescriptor {
@@ -88,14 +71,14 @@ impl AnchorDescriptor {
        pub fn unsigned_tx_input(&self) -> TxIn {
                TxIn {
                        previous_output: self.outpoint.clone(),
-                       script_sig: Script::new(),
+                       script_sig: ScriptBuf::new(),
                        sequence: Sequence::ENABLE_RBF_NO_LOCKTIME,
                        witness: Witness::new(),
                }
        }
 
        /// Returns the witness script of the anchor output in the commitment transaction.
-       pub fn witness_script(&self) -> Script {
+       pub fn witness_script(&self) -> ScriptBuf {
                let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
                chan_utils::get_anchor_redeemscript(&channel_params.broadcaster_pubkeys().funding_pubkey)
        }
@@ -110,126 +93,7 @@ impl AnchorDescriptor {
        /// Derives the channel signer required to sign the anchor input.
        pub fn derive_channel_signer<S: WriteableEcdsaChannelSigner, SP: Deref>(&self, signer_provider: &SP) -> S
        where
-               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_writeable_tlv_based!(HTLCDescriptor, {
-    (0, channel_derivation_parameters, required),
-    (2, commitment_txid, required),
-    (4, per_commitment_number, required),
-    (6, per_commitment_point, required),
-    (8, htlc, required),
-    (10, preimage, option),
-    (12, counterparty_sig, required),
-});
-
-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>
+               SP::Target: SignerProvider<EcdsaSigner= S>
        {
                let mut signer = signer_provider.derive_channel_signer(
                        self.channel_derivation_parameters.value_satoshis,
@@ -279,8 +143,8 @@ pub enum BumpTransactionEvent {
        /// an empty `pending_htlcs`), confirmation of the commitment transaction can be considered to
        /// be not urgent.
        ///
-       /// [`EcdsaChannelSigner`]: crate::sign::EcdsaChannelSigner
-       /// [`EcdsaChannelSigner::sign_holder_anchor_input`]: crate::sign::EcdsaChannelSigner::sign_holder_anchor_input
+       /// [`EcdsaChannelSigner`]: crate::sign::ecdsa::EcdsaChannelSigner
+       /// [`EcdsaChannelSigner::sign_holder_anchor_input`]: crate::sign::ecdsa::EcdsaChannelSigner::sign_holder_anchor_input
        /// [`build_anchor_input_witness`]: crate::ln::chan_utils::build_anchor_input_witness
        ChannelClose {
                /// The unique identifier for the claim of the anchor output in the commitment transaction.
@@ -333,9 +197,8 @@ pub enum BumpTransactionEvent {
        /// 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.
        ///
-       /// [`EcdsaChannelSigner`]: crate::sign::EcdsaChannelSigner
-       /// [`EcdsaChannelSigner::sign_holder_htlc_transaction`]: crate::sign::EcdsaChannelSigner::sign_holder_htlc_transaction
-       /// [`HTLCDescriptor::tx_input_witness`]: HTLCDescriptor::tx_input_witness
+       /// [`EcdsaChannelSigner`]: crate::sign::ecdsa::EcdsaChannelSigner
+       /// [`EcdsaChannelSigner::sign_holder_htlc_transaction`]: crate::sign::ecdsa::EcdsaChannelSigner::sign_holder_htlc_transaction
        HTLCResolution {
                /// The unique identifier for the claim of the HTLCs in the confirmed commitment
                /// transaction.
@@ -350,7 +213,7 @@ pub enum BumpTransactionEvent {
                /// by the same transaction.
                htlc_descriptors: Vec<HTLCDescriptor>,
                /// The locktime required for the resulting HTLC transaction.
-               tx_lock_time: PackedLockTime,
+               tx_lock_time: LockTime,
        },
 }
 
@@ -384,12 +247,6 @@ pub struct Utxo {
 }
 
 impl Utxo {
-       const P2WPKH_WITNESS_WEIGHT: u64 = 1 /* num stack items */ +
-               1 /* sig length */ +
-               73 /* sig including sighash flag */ +
-               1 /* pubkey length */ +
-               33 /* pubkey */;
-
        /// Returns a `Utxo` with the `satisfaction_weight` estimate for a legacy P2PKH output.
        pub fn new_p2pkh(outpoint: OutPoint, value: u64, pubkey_hash: &PubkeyHash) -> Self {
                let script_sig_size = 1 /* script_sig length */ +
@@ -401,7 +258,7 @@ impl Utxo {
                        outpoint,
                        output: TxOut {
                                value,
-                               script_pubkey: Script::new_p2pkh(pubkey_hash),
+                               script_pubkey: ScriptBuf::new_p2pkh(pubkey_hash),
                        },
                        satisfaction_weight: script_sig_size * WITNESS_SCALE_FACTOR as u64 + 1 /* empty witness */,
                }
@@ -417,9 +274,9 @@ impl Utxo {
                        outpoint,
                        output: TxOut {
                                value,
-                               script_pubkey: Script::new_p2sh(&Script::new_v0_p2wpkh(pubkey_hash).script_hash()),
+                               script_pubkey: ScriptBuf::new_p2sh(&ScriptBuf::new_v0_p2wpkh(pubkey_hash).script_hash()),
                        },
-                       satisfaction_weight: script_sig_size * WITNESS_SCALE_FACTOR as u64 + Self::P2WPKH_WITNESS_WEIGHT,
+                       satisfaction_weight: script_sig_size * WITNESS_SCALE_FACTOR as u64 + P2WPKH_WITNESS_WEIGHT,
                }
        }
 
@@ -429,9 +286,9 @@ impl Utxo {
                        outpoint,
                        output: TxOut {
                                value,
-                               script_pubkey: Script::new_v0_p2wpkh(pubkey_hash),
+                               script_pubkey: ScriptBuf::new_v0_p2wpkh(pubkey_hash),
                        },
-                       satisfaction_weight: EMPTY_SCRIPT_SIG_WEIGHT + Self::P2WPKH_WITNESS_WEIGHT,
+                       satisfaction_weight: EMPTY_SCRIPT_SIG_WEIGHT + P2WPKH_WITNESS_WEIGHT,
                }
        }
 }
@@ -487,7 +344,10 @@ pub trait CoinSelectionSource {
        ) -> Result<CoinSelection, ()>;
        /// Signs and provides the full witness for all inputs within the transaction known to the
        /// trait (i.e., any provided via [`CoinSelectionSource::select_confirmed_utxos`]).
-       fn sign_tx(&self, tx: Transaction) -> Result<Transaction, ()>;
+       ///
+       /// If your wallet does not support signing PSBTs you can call `psbt.extract_tx()` to get the
+       /// unsigned transaction and then sign it with your wallet.
+       fn sign_psbt(&self, psbt: PartiallySignedTransaction) -> Result<Transaction, ()>;
 }
 
 /// An alternative to [`CoinSelectionSource`] that can be implemented and used along [`Wallet`] to
@@ -497,11 +357,14 @@ pub trait WalletSource {
        fn list_confirmed_utxos(&self) -> Result<Vec<Utxo>, ()>;
        /// Returns a script to use for change above dust resulting from a successful coin selection
        /// attempt.
-       fn get_change_script(&self) -> Result<Script, ()>;
+       fn get_change_script(&self) -> Result<ScriptBuf, ()>;
        /// Signs and provides the full [`TxIn::script_sig`] and [`TxIn::witness`] for all inputs within
        /// the transaction known to the wallet (i.e., any provided via
        /// [`WalletSource::list_confirmed_utxos`]).
-       fn sign_tx(&self, tx: Transaction) -> Result<Transaction, ()>;
+       ///
+       /// If your wallet does not support signing PSBTs you can call `psbt.extract_tx()` to get the
+       /// unsigned transaction and then sign it with your wallet.
+       fn sign_psbt(&self, psbt: PartiallySignedTransaction) -> Result<Transaction, ()>;
 }
 
 /// A wrapper over [`WalletSource`] that implements [`CoinSelection`] by preferring UTXOs that would
@@ -553,7 +416,7 @@ where
                                }
                        }
                        let fee_to_spend_utxo = fee_for_weight(
-                               target_feerate_sat_per_1000_weight, BASE_INPUT_WEIGHT as u64 + utxo.satisfaction_weight,
+                               target_feerate_sat_per_1000_weight, BASE_INPUT_WEIGHT + utxo.satisfaction_weight,
                        );
                        let should_spend = if tolerate_high_network_feerates {
                                utxo.output.value > fee_to_spend_utxo
@@ -648,8 +511,8 @@ where
                        .or_else(|_| do_coin_selection(true, true))
        }
 
-       fn sign_tx(&self, tx: Transaction) -> Result<Transaction, ()> {
-               self.source.sign_tx(tx)
+       fn sign_psbt(&self, psbt: PartiallySignedTransaction) -> Result<Transaction, ()> {
+               self.source.sign_psbt(psbt)
        }
 }
 
@@ -693,16 +556,16 @@ where
        }
 
        /// Updates a transaction with the result of a successful coin selection attempt.
-       fn process_coin_selection(&self, tx: &mut Transaction, mut coin_selection: CoinSelection) {
-               for utxo in coin_selection.confirmed_utxos.drain(..) {
+       fn process_coin_selection(&self, tx: &mut Transaction, coin_selection: &CoinSelection) {
+               for utxo in coin_selection.confirmed_utxos.iter() {
                        tx.input.push(TxIn {
                                previous_output: utxo.outpoint,
-                               script_sig: Script::new(),
+                               script_sig: ScriptBuf::new(),
                                sequence: Sequence::ZERO,
                                witness: Witness::new(),
                        });
                }
-               if let Some(change_output) = coin_selection.change_output.take() {
+               if let Some(change_output) = coin_selection.change_output.clone() {
                        tx.output.push(change_output);
                } else if tx.output.is_empty() {
                        // We weren't provided a change output, likely because the input set was a perfect
@@ -712,7 +575,7 @@ where
                        log_debug!(self.logger, "Including dummy OP_RETURN output since an output is needed and a change output was not provided");
                        tx.output.push(TxOut {
                                value: 0,
-                               script_pubkey: Script::new_op_return(&[]),
+                               script_pubkey: ScriptBuf::new_op_return(&[]),
                        });
                }
        }
@@ -732,20 +595,20 @@ where
                let must_spend = vec![Input {
                        outpoint: anchor_descriptor.outpoint,
                        previous_utxo: anchor_utxo,
-                       satisfaction_weight: commitment_tx.weight() as u64 + ANCHOR_INPUT_WITNESS_WEIGHT + EMPTY_SCRIPT_SIG_WEIGHT,
+                       satisfaction_weight: commitment_tx.weight().to_wu() + ANCHOR_INPUT_WITNESS_WEIGHT + EMPTY_SCRIPT_SIG_WEIGHT,
                }];
                #[cfg(debug_assertions)]
                let must_spend_amount = must_spend.iter().map(|input| input.previous_utxo.value).sum::<u64>();
 
                log_debug!(self.logger, "Peforming coin selection for commitment package (commitment and anchor transaction) targeting {} sat/kW",
                        package_target_feerate_sat_per_1000_weight);
-               let coin_selection = self.utxo_source.select_confirmed_utxos(
+               let coin_selection: CoinSelection = self.utxo_source.select_confirmed_utxos(
                        claim_id, must_spend, &[], package_target_feerate_sat_per_1000_weight,
                )?;
 
                let mut anchor_tx = Transaction {
                        version: 2,
-                       lock_time: PackedLockTime::ZERO, // TODO: Use next best height.
+                       lock_time: LockTime::ZERO, // TODO: Use next best height.
                        input: vec![anchor_descriptor.unsigned_tx_input()],
                        output: vec![],
                };
@@ -757,22 +620,36 @@ where
                let total_input_amount = must_spend_amount +
                        coin_selection.confirmed_utxos.iter().map(|utxo| utxo.output.value).sum::<u64>();
 
-               self.process_coin_selection(&mut anchor_tx, coin_selection);
+               self.process_coin_selection(&mut anchor_tx, &coin_selection);
                let anchor_txid = anchor_tx.txid();
 
-               debug_assert_eq!(anchor_tx.output.len(), 1);
+               // construct psbt
+               let mut anchor_psbt = PartiallySignedTransaction::from_unsigned_tx(anchor_tx).unwrap();
+               // add witness_utxo to anchor input
+               anchor_psbt.inputs[0].witness_utxo = Some(anchor_descriptor.previous_utxo());
+               // add witness_utxo to remaining inputs
+               for (idx, utxo) in coin_selection.confirmed_utxos.into_iter().enumerate() {
+                       // add 1 to skip the anchor input
+                       let index = idx + 1;
+                       debug_assert_eq!(anchor_psbt.unsigned_tx.input[index].previous_output, utxo.outpoint);
+                       if utxo.output.script_pubkey.is_witness_program() {
+                               anchor_psbt.inputs[index].witness_utxo = Some(utxo.output);
+                       }
+               }
+
+               debug_assert_eq!(anchor_psbt.unsigned_tx.output.len(), 1);
                #[cfg(debug_assertions)]
-               let unsigned_tx_weight = anchor_tx.weight() as u64 - (anchor_tx.input.len() as u64 * EMPTY_SCRIPT_SIG_WEIGHT);
+               let unsigned_tx_weight = anchor_psbt.unsigned_tx.weight().to_wu() - (anchor_psbt.unsigned_tx.input.len() as u64 * EMPTY_SCRIPT_SIG_WEIGHT);
 
                log_debug!(self.logger, "Signing anchor transaction {}", anchor_txid);
-               anchor_tx = self.utxo_source.sign_tx(anchor_tx)?;
+               anchor_tx = self.utxo_source.sign_psbt(anchor_psbt)?;
 
                let signer = anchor_descriptor.derive_channel_signer(&self.signer_provider);
                let anchor_sig = signer.sign_holder_anchor_input(&anchor_tx, 0, &self.secp)?;
                anchor_tx.input[0].witness = anchor_descriptor.tx_input_witness(&anchor_sig);
 
                #[cfg(debug_assertions)] {
-                       let signed_tx_weight = anchor_tx.weight() as u64;
+                       let signed_tx_weight = anchor_tx.weight().to_wu();
                        let expected_signed_tx_weight = unsigned_tx_weight + total_satisfaction_weight;
                        // Our estimate should be within a 1% error margin of the actual weight and we should
                        // never underestimate.
@@ -780,7 +657,7 @@ where
                                expected_signed_tx_weight - (expected_signed_tx_weight / 100) <= signed_tx_weight);
 
                        let expected_package_fee = fee_for_weight(package_target_feerate_sat_per_1000_weight,
-                               signed_tx_weight + commitment_tx.weight() as u64);
+                               signed_tx_weight + commitment_tx.weight().to_wu());
                        let package_fee = total_input_amount -
                                anchor_tx.output.iter().map(|output| output.value).sum::<u64>();
                        // Our fee should be within a 5% error margin of the expected fee based on the
@@ -800,7 +677,7 @@ where
        /// fully-signed, fee-bumped HTLC transaction that is broadcast to the network.
        fn handle_htlc_resolution(
                &self, claim_id: ClaimId, target_feerate_sat_per_1000_weight: u32,
-               htlc_descriptors: &[HTLCDescriptor], tx_lock_time: PackedLockTime,
+               htlc_descriptors: &[HTLCDescriptor], tx_lock_time: LockTime,
        ) -> Result<(), ()> {
                let mut htlc_tx = Transaction {
                        version: 2,
@@ -834,7 +711,7 @@ where
                #[cfg(debug_assertions)]
                let must_spend_amount = must_spend.iter().map(|input| input.previous_utxo.value).sum::<u64>();
 
-               let coin_selection = self.utxo_source.select_confirmed_utxos(
+               let coin_selection: CoinSelection = self.utxo_source.select_confirmed_utxos(
                        claim_id, must_spend, &htlc_tx.output, target_feerate_sat_per_1000_weight,
                )?;
 
@@ -845,13 +722,30 @@ where
                let total_input_amount = must_spend_amount +
                        coin_selection.confirmed_utxos.iter().map(|utxo| utxo.output.value).sum::<u64>();
 
-               self.process_coin_selection(&mut htlc_tx, coin_selection);
+               self.process_coin_selection(&mut htlc_tx, &coin_selection);
+
+               // construct psbt
+               let mut htlc_psbt = PartiallySignedTransaction::from_unsigned_tx(htlc_tx).unwrap();
+               // add witness_utxo to htlc inputs
+               for (i, htlc_descriptor) in htlc_descriptors.iter().enumerate() {
+                       debug_assert_eq!(htlc_psbt.unsigned_tx.input[i].previous_output, htlc_descriptor.outpoint());
+                       htlc_psbt.inputs[i].witness_utxo = Some(htlc_descriptor.previous_utxo(&self.secp));
+               }
+               // add witness_utxo to remaining inputs
+               for (idx, utxo) in coin_selection.confirmed_utxos.into_iter().enumerate() {
+                       // offset to skip the htlc inputs
+                       let index = idx + htlc_descriptors.len();
+                       debug_assert_eq!(htlc_psbt.unsigned_tx.input[index].previous_output, utxo.outpoint);
+                       if utxo.output.script_pubkey.is_witness_program() {
+                               htlc_psbt.inputs[index].witness_utxo = Some(utxo.output);
+                       }
+               }
 
                #[cfg(debug_assertions)]
-               let unsigned_tx_weight = htlc_tx.weight() as u64 - (htlc_tx.input.len() as u64 * EMPTY_SCRIPT_SIG_WEIGHT);
+               let unsigned_tx_weight = htlc_psbt.unsigned_tx.weight().to_wu() - (htlc_psbt.unsigned_tx.input.len() as u64 * EMPTY_SCRIPT_SIG_WEIGHT);
 
-               log_debug!(self.logger, "Signing HTLC transaction {}", htlc_tx.txid());
-               htlc_tx = self.utxo_source.sign_tx(htlc_tx)?;
+               log_debug!(self.logger, "Signing HTLC transaction {}", htlc_psbt.unsigned_tx.txid());
+               htlc_tx = self.utxo_source.sign_psbt(htlc_psbt)?;
 
                let mut signers = BTreeMap::new();
                for (idx, htlc_descriptor) in htlc_descriptors.iter().enumerate() {
@@ -863,7 +757,7 @@ where
                }
 
                #[cfg(debug_assertions)] {
-                       let signed_tx_weight = htlc_tx.weight() as u64;
+                       let signed_tx_weight = htlc_tx.weight().to_wu();
                        let expected_signed_tx_weight = unsigned_tx_weight + total_satisfaction_weight;
                        // Our estimate should be within a 1% error margin of the actual weight and we should
                        // never underestimate.