Insert channel funding outputs into Wallet

bindings/ldk_node.udl

@@ -339,6 +339,7 @@ enum NodeError {
 	"InvalidNodeAlias",
 	"InvalidDateTime",
 	"InvalidFeeRate",
+	"InvalidScriptPubKey",
 	"DuplicatePayment",
 	"UnsupportedCurrency",
 	"InsufficientFunds",
@@ -575,6 +576,7 @@ dictionary ChannelDetails {
 	ChannelId channel_id;
 	PublicKey counterparty_node_id;
 	OutPoint? funding_txo;
+	ScriptBuf? funding_redeem_script;
 	u64? short_channel_id;
 	u64? outbound_scid_alias;
 	u64? inbound_scid_alias;
@@ -901,3 +903,6 @@ typedef string LSPS1OrderId;
 
 [Custom]
 typedef string LSPSDateTime;
+
+[Custom]
+typedef string ScriptBuf;

src/error.rs

@@ -113,6 +113,8 @@ pub enum Error {
 	InvalidDateTime,
 	/// The given fee rate is invalid.
 	InvalidFeeRate,
+	/// The given script public key is invalid.
+	InvalidScriptPubKey,
 	/// A payment with the given hash has already been initiated.
 	DuplicatePayment,
 	/// The provided offer was denonminated in an unsupported currency.
@@ -186,6 +188,7 @@ impl fmt::Display for Error {
 			Self::InvalidNodeAlias => write!(f, "The given node alias is invalid."),
 			Self::InvalidDateTime => write!(f, "The given date time is invalid."),
 			Self::InvalidFeeRate => write!(f, "The given fee rate is invalid."),
+			Self::InvalidScriptPubKey => write!(f, "The given script pubkey is invalid."),
 			Self::DuplicatePayment => {
 				write!(f, "A payment with the given hash has already been initiated.")
 			},

src/event.rs

@@ -1458,6 +1458,33 @@ where
 						counterparty_node_id,
 						funding_txo,
 					);
+
+					let chans =
+						self.channel_manager.list_channels_with_counterparty(&counterparty_node_id);
+					let chan_output = chans
+						.iter()
+						.find(|c| c.user_channel_id == user_channel_id)
+						.and_then(|c| c.get_funding_output());
+					match chan_output {
+						None => {
+							log_error!(
+								self.logger,
+								"Failed to find channel info for pending channel {channel_id} with counterparty {counterparty_node_id}"
+							);
+							debug_assert!(false,
+								"Failed to find channel info for pending channel {channel_id} with counterparty {counterparty_node_id}"
+							);
+						},
+						Some(output) => {
+							if let Err(e) = self.wallet.insert_txo(funding_txo, output) {
+								log_error!(
+									self.logger,
+									"Failed to insert funding TXO into wallet: {e}"
+								);
+								return Err(ReplayEvent());
+							}
+						},
+					}
 				} else {
 					log_info!(
 						self.logger,

src/ffi/types.rs

@@ -20,7 +20,7 @@ pub use bip39::Mnemonic;
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::hashes::Hash;
 use bitcoin::secp256k1::PublicKey;
-pub use bitcoin::{Address, BlockHash, FeeRate, Network, OutPoint, Txid};
+pub use bitcoin::{Address, BlockHash, FeeRate, Network, OutPoint, ScriptBuf, Txid};
 pub use lightning::chain::channelmonitor::BalanceSource;
 pub use lightning::events::{ClosureReason, PaymentFailureReason};
 use lightning::ln::channelmanager::PaymentId;
@@ -106,6 +106,22 @@ impl UniffiCustomTypeConverter for Address {
 	}
 }
 
+impl UniffiCustomTypeConverter for ScriptBuf {
+	type Builtin = String;
+
+	fn into_custom(val: Self::Builtin) -> uniffi::Result<Self> {
+		if let Ok(key) = ScriptBuf::from_hex(&val) {
+			return Ok(key);
+		}
+
+		Err(Error::InvalidScriptPubKey.into())
+	}
+
+	fn from_custom(obj: Self) -> Self::Builtin {
+		obj.to_string()
+	}
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum OfferAmount {
 	Bitcoin { amount_msats: u64 },

src/lib.rs

@@ -138,7 +138,7 @@ use io::utils::write_node_metrics;
 use lightning::chain::BestBlock;
 use lightning::events::bump_transaction::{Input, Wallet as LdkWallet};
 use lightning::impl_writeable_tlv_based;
-use lightning::ln::chan_utils::{make_funding_redeemscript, FUNDING_TRANSACTION_WITNESS_WEIGHT};
+use lightning::ln::chan_utils::FUNDING_TRANSACTION_WITNESS_WEIGHT;
 use lightning::ln::channel_state::{ChannelDetails as LdkChannelDetails, ChannelShutdownState};
 use lightning::ln::channelmanager::PaymentId;
 use lightning::ln::funding::SpliceContribution;
@@ -1267,29 +1267,27 @@ impl Node {
 			const EMPTY_SCRIPT_SIG_WEIGHT: u64 =
 				1 /* empty script_sig */ * bitcoin::constants::WITNESS_SCALE_FACTOR as u64;
 
-			// Used for creating a redeem script for the previous funding txo and the new funding
-			// txo. Only needed when selecting which UTXOs to include in the funding tx that would
-			// be sufficient to pay for fees. Hence, the value does not matter.
-			let dummy_pubkey = PublicKey::from_slice(&[2; 33]).unwrap();
-
 			let funding_txo = channel_details.funding_txo.ok_or_else(|| {
 				log_error!(self.logger, "Failed to splice channel: channel not yet ready",);
 				Error::ChannelSplicingFailed
 			})?;
 
+			let funding_output = channel_details.get_funding_output().ok_or_else(|| {
+				log_error!(self.logger, "Failed to splice channel: channel not yet ready");
+				Error::ChannelSplicingFailed
+			})?;
+
 			let shared_input = Input {
 				outpoint: funding_txo.into_bitcoin_outpoint(),
-				previous_utxo: bitcoin::TxOut {
-					value: Amount::from_sat(channel_details.channel_value_satoshis),
-					script_pubkey: make_funding_redeemscript(&dummy_pubkey, &dummy_pubkey)
-						.to_p2wsh(),
-				},
+				previous_utxo: funding_output.clone(),
 				satisfaction_weight: EMPTY_SCRIPT_SIG_WEIGHT + FUNDING_TRANSACTION_WITNESS_WEIGHT,
 			};
 
 			let shared_output = bitcoin::TxOut {
 				value: shared_input.previous_utxo.value + Amount::from_sat(splice_amount_sats),
-				script_pubkey: make_funding_redeemscript(&dummy_pubkey, &dummy_pubkey).to_p2wsh(),
+				// will not actually be the exact same script pubkey after splice
+				// but it is the same size and good enough for coin selection purposes
+				script_pubkey: funding_output.script_pubkey.clone(),
 			};
 
 			let fee_rate = self.fee_estimator.estimate_fee_rate(ConfirmationTarget::ChannelFunding);
@@ -1321,6 +1319,15 @@ impl Node {
 				},
 			};
 
+			// insert channel's funding utxo into the wallet so we can later calculate fees
+			// correctly when viewing this splice-in.
+			self.wallet.insert_txo(funding_txo.into_bitcoin_outpoint(), funding_output).map_err(
+				|e| {
+					log_error!(self.logger, "Failed to splice channel: {:?}", e);
+					Error::ChannelSplicingFailed
+				},
+			)?;
+
 			self.channel_manager
 				.splice_channel(
 					&channel_details.channel_id,

src/types.rs

@@ -222,6 +222,15 @@ pub struct ChannelDetails {
 	/// state until the splice transaction reaches sufficient confirmations to be locked (and we
 	/// exchange `splice_locked` messages with our peer).
 	pub funding_txo: Option<OutPoint>,
+	/// The witness script that is used to lock the channel's funding output to commitment transactions.
+	///
+	/// This field will be `None` if we have not negotiated the funding transaction with our
+	/// counterparty already.
+	///
+	/// When a channel is spliced, this continues to refer to the original pre-splice channel
+	/// state until the splice transaction reaches sufficient confirmations to be locked (and we
+	/// exchange `splice_locked` messages with our peer).
+	pub funding_redeem_script: Option<bitcoin::ScriptBuf>,
 	/// The position of the funding transaction in the chain. None if the funding transaction has
 	/// not yet been confirmed and the channel fully opened.
 	///
@@ -378,6 +387,7 @@ impl From<LdkChannelDetails> for ChannelDetails {
 			channel_id: value.channel_id,
 			counterparty_node_id: value.counterparty.node_id,
 			funding_txo: value.funding_txo.map(|o| o.into_bitcoin_outpoint()),
+			funding_redeem_script: value.funding_redeem_script,
 			short_channel_id: value.short_channel_id,
 			outbound_scid_alias: value.outbound_scid_alias,
 			inbound_scid_alias: value.inbound_scid_alias,

src/wallet/mod.rs

@@ -26,7 +26,7 @@ use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1::ecdsa::{RecoverableSignature, Signature};
 use bitcoin::secp256k1::{All, PublicKey, Scalar, Secp256k1, SecretKey};
 use bitcoin::{
-	Address, Amount, FeeRate, ScriptBuf, Transaction, TxOut, Txid, WPubkeyHash, Weight,
+	Address, Amount, FeeRate, OutPoint, ScriptBuf, Transaction, TxOut, Txid, WPubkeyHash, Weight,
 	WitnessProgram, WitnessVersion,
 };
 use lightning::chain::chaininterface::BroadcasterInterface;
@@ -153,6 +153,19 @@ impl Wallet {
 		Ok(())
 	}
 
+	pub(crate) fn insert_txo(&self, outpoint: OutPoint, txout: TxOut) -> Result<(), Error> {
+		let mut locked_wallet = self.inner.lock().unwrap();
+		locked_wallet.insert_txout(outpoint, txout);
+
+		let mut locked_persister = self.persister.lock().unwrap();
+		locked_wallet.persist(&mut locked_persister).map_err(|e| {
+			log_error!(self.logger, "Failed to persist wallet: {}", e);
+			Error::PersistenceFailed
+		})?;
+
+		Ok(())
+	}
+
 	fn update_payment_store<'a>(
 		&self, locked_wallet: &'a mut PersistedWallet<KVStoreWalletPersister>,
 	) -> Result<(), Error> {

tests/integration_tests_rust.rs

@@ -995,7 +995,7 @@ async fn splice_channel() {
 	// Splice-in funds for Node B so that it has outbound liquidity to make a payment
 	node_b.splice_in(&user_channel_id_b, node_a.node_id(), 4_000_000).unwrap();
 
-	expect_splice_pending_event!(node_a, node_b.node_id());
+	let txo = expect_splice_pending_event!(node_a, node_b.node_id());
 	expect_splice_pending_event!(node_b, node_a.node_id());
 
 	generate_blocks_and_wait(&bitcoind.client, &electrsd.client, 6).await;
@@ -1006,11 +1006,16 @@ async fn splice_channel() {
 	expect_channel_ready_event!(node_a, node_b.node_id());
 	expect_channel_ready_event!(node_b, node_a.node_id());
 
-	let splice_in_fee_sat = 252;
+	let expected_splice_in_fee_sat = 252;
+
+	let payments = node_b.list_payments();
+	let payment =
+		payments.into_iter().find(|p| p.id == PaymentId(txo.txid.to_byte_array())).unwrap();
+	assert_eq!(payment.fee_paid_msat, Some(expected_splice_in_fee_sat * 1_000));
 
 	assert_eq!(
 		node_b.list_balances().total_onchain_balance_sats,
-		premine_amount_sat - 4_000_000 - splice_in_fee_sat
+		premine_amount_sat - 4_000_000 - expected_splice_in_fee_sat
 	);
 	assert_eq!(node_b.list_balances().total_lightning_balance_sats, 4_000_000);