Refactor liquidity source to support multiple LSP nodes

Replace per-protocol single-LSP configuration `LSPS1Client, LSPS2Client`
with a unified `Vec<LspNode>` model where users configure LSP nodes via
`add_lsp()` and protocol support is discovered at runtime via LSPS0
`list_protocols`.

- Replace separate `LSPS1Client/LSPS2Client` with global pending request
  maps keyed by `LSPSRequestId`
- Add LSPS0 protocol discovery `discover_lsp_protocols` with event
  handling for `ListProtocolsResponse`
- Update events to use is_lsps_node() for multi-LSP counterparty
  checks
- Deprecate `set_liquidity_source_lsps1/lsps2` builder methods in favor
  of `add_lsp()`
- LSPS2 JIT channels now query all LSPS2-capable LSPs and automatically
  select the cheapest fee offer across all of them
- Add `request_channel_from_lsp()` for explicit LSPS1 LSP selection
- Spawn background discovery task on `Node::start()`

Author: Camillarhi

bindings/ldk_node.udl

@@ -43,8 +43,7 @@ interface Builder {
 	void set_gossip_source_p2p();
 	void set_gossip_source_rgs(string rgs_server_url);
 	void set_pathfinding_scores_source(string url);
-	void set_liquidity_source_lsps1(PublicKey node_id, SocketAddress address, string? token);
-	void set_liquidity_source_lsps2(PublicKey node_id, SocketAddress address, string? token);
+	void add_lsp(PublicKey node_id, SocketAddress address, string? token);
 	void set_storage_dir_path(string storage_dir_path);
 	void set_filesystem_logger(string? log_file_path, LogLevel? max_log_level);
 	void set_log_facade_logger();
@@ -97,7 +96,7 @@ interface Node {
 	SpontaneousPayment spontaneous_payment();
 	OnchainPayment onchain_payment();
 	UnifiedPayment unified_payment();
-	LSPS1Liquidity lsps1_liquidity();
+	Liquidity liquidity();
 	[Throws=NodeError]
 	void lnurl_auth(string lnurl);
 	[Throws=NodeError]
@@ -161,7 +160,7 @@ interface FeeRate {
 
 typedef interface UnifiedPayment;
 
-typedef interface LSPS1Liquidity;
+typedef interface Liquidity;
 
 [Error]
 enum NodeError {

src/builder.rs

@@ -65,9 +65,7 @@ use crate::io::{
 	PENDING_PAYMENT_INFO_PERSISTENCE_PRIMARY_NAMESPACE,
 	PENDING_PAYMENT_INFO_PERSISTENCE_SECONDARY_NAMESPACE,
 };
-use crate::liquidity::{
-	LSPS1ClientConfig, LSPS2ClientConfig, LSPS2ServiceConfig, LiquiditySourceBuilder,
-};
+use crate::liquidity::{LSPS2ServiceConfig, LiquiditySourceBuilder, LspConfig};
 use crate::lnurl_auth::LnurlAuth;
 use crate::logger::{log_error, LdkLogger, LogLevel, LogWriter, Logger};
 use crate::message_handler::NodeCustomMessageHandler;
@@ -120,10 +118,8 @@ struct PathfindingScoresSyncConfig {
 
 #[derive(Debug, Clone, Default)]
 struct LiquiditySourceConfig {
-	// Act as an LSPS1 client connecting to the given service.
-	lsps1_client: Option<LSPS1ClientConfig>,
-	// Act as an LSPS2 client connecting to the given service.
-	lsps2_client: Option<LSPS2ClientConfig>,
+	// Acts for both LSPS1 and LSPS2 clients connecting to the given service.
+	lsp_nodes: Vec<LspConfig>,
 	// Act as an LSPS2 service.
 	lsps2_service: Option<LSPS2ServiceConfig>,
 }
@@ -432,45 +428,24 @@ impl NodeBuilder {
 		self
 	}
 
-	/// Configures the [`Node`] instance to source inbound liquidity from the given
-	/// [bLIP-51 / LSPS1] service.
-	///
-	/// Will mark the LSP as trusted for 0-confirmation channels, see [`Config::trusted_peers_0conf`].
-	///
-	/// The given `token` will be used by the LSP to authenticate the user.
-	///
-	/// [bLIP-51 / LSPS1]: https://github.com/lightning/blips/blob/master/blip-0051.md
-	pub fn set_liquidity_source_lsps1(
-		&mut self, node_id: PublicKey, address: SocketAddress, token: Option<String>,
-	) -> &mut Self {
-		// Mark the LSP as trusted for 0conf
-		self.config.trusted_peers_0conf.push(node_id.clone());
-
-		let liquidity_source_config =
-			self.liquidity_source_config.get_or_insert(LiquiditySourceConfig::default());
-		let lsps1_client_config = LSPS1ClientConfig { node_id, address, token };
-		liquidity_source_config.lsps1_client = Some(lsps1_client_config);
-		self
-	}
-
-	/// Configures the [`Node`] instance to source just-in-time inbound liquidity from the given
-	/// [bLIP-52 / LSPS2] service.
+	/// Configures the [`Node`] instance to source inbound liquidity from the given LSP, without specifying
+	/// the exact protocol used (e.g., LSPS1 or LSPS2).
 	///
 	/// Will mark the LSP as trusted for 0-confirmation channels, see [`Config::trusted_peers_0conf`].
 	///
 	/// The given `token` will be used by the LSP to authenticate the user.
-	///
-	/// [bLIP-52 / LSPS2]: https://github.com/lightning/blips/blob/master/blip-0052.md
-	pub fn set_liquidity_source_lsps2(
+	/// This method is useful when the user wants to connect to an LSP but does not want to be concerned with
+	///  the specific protocol used for liquidity provision. The node will automatically detect and use the
+	/// appropriate protocol supported by the LSP.
+	pub fn add_lsp(
 		&mut self, node_id: PublicKey, address: SocketAddress, token: Option<String>,
 	) -> &mut Self {
 		// Mark the LSP as trusted for 0conf
-		self.config.trusted_peers_0conf.push(node_id.clone());
+		self.config.trusted_peers_0conf.push(node_id);
 
 		let liquidity_source_config =
 			self.liquidity_source_config.get_or_insert(LiquiditySourceConfig::default());
-		let lsps2_client_config = LSPS2ClientConfig { node_id, address, token };
-		liquidity_source_config.lsps2_client = Some(lsps2_client_config);
+		liquidity_source_config.lsp_nodes.push(LspConfig { node_id, address, token });
 		self
 	}
 
@@ -953,32 +928,16 @@ impl ArcedNodeBuilder {
 		self.inner.write().unwrap().set_pathfinding_scores_source(url);
 	}
 
-	/// Configures the [`Node`] instance to source inbound liquidity from the given
-	/// [bLIP-51 / LSPS1] service.
+	/// Configures the [`Node`] instance to source inbound liquidity from the given LSP.
 	///
 	/// Will mark the LSP as trusted for 0-confirmation channels, see [`Config::trusted_peers_0conf`].
 	///
 	/// The given `token` will be used by the LSP to authenticate the user.
-	///
-	/// [bLIP-51 / LSPS1]: https://github.com/lightning/blips/blob/master/blip-0051.md
-	pub fn set_liquidity_source_lsps1(
-		&self, node_id: PublicKey, address: SocketAddress, token: Option<String>,
-	) {
-		self.inner.write().unwrap().set_liquidity_source_lsps1(node_id, address, token);
-	}
-
-	/// Configures the [`Node`] instance to source just-in-time inbound liquidity from the given
-	/// [bLIP-52 / LSPS2] service.
-	///
-	/// Will mark the LSP as trusted for 0-confirmation channels, see [`Config::trusted_peers_0conf`].
-	///
-	/// The given `token` will be used by the LSP to authenticate the user.
-	///
-	/// [bLIP-52 / LSPS2]: https://github.com/lightning/blips/blob/master/blip-0052.md
-	pub fn set_liquidity_source_lsps2(
-		&self, node_id: PublicKey, address: SocketAddress, token: Option<String>,
-	) {
-		self.inner.write().unwrap().set_liquidity_source_lsps2(node_id, address, token);
+	/// This method is useful when the user wants to connect to an LSP but does not want to be concerned with
+	///  the specific protocol used for liquidity provision. The node will automatically detect and use the
+	/// appropriate protocol supported by the LSP.
+	pub fn add_lsp(&self, node_id: PublicKey, address: SocketAddress, token: Option<String>) {
+		self.inner.write().unwrap().add_lsp(node_id, address, token);
 	}
 
 	/// Configures the [`Node`] instance to provide an [LSPS2] service, issuing just-in-time
@@ -1802,21 +1761,7 @@ fn build_with_store_internal(
 				Arc::clone(&logger),
 			);
 
-			lsc.lsps1_client.as_ref().map(|config| {
-				liquidity_source_builder.lsps1_client(
-					config.node_id,
-					config.address.clone(),
-					config.token.clone(),
-				)
-			});
-
-			lsc.lsps2_client.as_ref().map(|config| {
-				liquidity_source_builder.lsps2_client(
-					config.node_id,
-					config.address.clone(),
-					config.token.clone(),
-				)
-			});
+			liquidity_source_builder.set_lsp_nodes(lsc.lsp_nodes.clone());
 
 			let promise_secret = {
 				let lsps_xpriv = derive_xprv(
@@ -1885,7 +1830,9 @@ fn build_with_store_internal(
 		}
 	}));
 
-	liquidity_source.as_ref().map(|l| l.set_peer_manager(Arc::downgrade(&peer_manager)));
+	liquidity_source
+		.as_ref()
+		.map(|l| l.lsps2_service().set_peer_manager(Arc::downgrade(&peer_manager)));
 
 	let connection_manager = Arc::new(ConnectionManager::new(
 		Arc::clone(&peer_manager),

src/event.rs

@@ -581,15 +581,15 @@ where
 					Ok(final_tx) => {
 						let needs_manual_broadcast =
 							self.liquidity_source.as_ref().map_or(false, |ls| {
-								ls.as_ref().lsps2_channel_needs_manual_broadcast(
+								ls.as_ref().lsps2_service().lsps2_channel_needs_manual_broadcast(
 									counterparty_node_id,
 									user_channel_id,
 								)
 							});
 
 						let result = if needs_manual_broadcast {
 							self.liquidity_source.as_ref().map(|ls| {
-								ls.lsps2_store_funding_transaction(
+								ls.lsps2_service().lsps2_store_funding_transaction(
 									user_channel_id,
 									counterparty_node_id,
 									final_tx.clone(),
@@ -653,7 +653,8 @@ where
 			},
 			LdkEvent::FundingTxBroadcastSafe { user_channel_id, counterparty_node_id, .. } => {
 				self.liquidity_source.as_ref().map(|ls| {
-					ls.lsps2_funding_tx_broadcast_safe(user_channel_id, counterparty_node_id);
+					ls.lsps2_service()
+						.lsps2_funding_tx_broadcast_safe(user_channel_id, counterparty_node_id);
 				});
 			},
 			LdkEvent::PaymentClaimable {
@@ -1139,7 +1140,10 @@ where
 			LdkEvent::ProbeFailed { .. } => {},
 			LdkEvent::HTLCHandlingFailed { failure_type, .. } => {
 				if let Some(liquidity_source) = self.liquidity_source.as_ref() {
-					liquidity_source.handle_htlc_handling_failed(failure_type).await;
+					liquidity_source
+						.lsps2_service()
+						.handle_htlc_handling_failed(failure_type)
+						.await;
 				}
 			},
 			LdkEvent::SpendableOutputs { outputs, channel_id, counterparty_node_id } => {
@@ -1238,14 +1242,15 @@ where
 				let user_channel_id: u128 = u128::from_ne_bytes(
 					self.keys_manager.get_secure_random_bytes()[..16].try_into().unwrap(),
 				);
-				let allow_0conf = self.config.trusted_peers_0conf.contains(&counterparty_node_id);
-				let mut channel_override_config = None;
-				if let Some((lsp_node_id, _)) = self
+				let is_lsp_node = self
 					.liquidity_source
 					.as_ref()
-					.and_then(|ls| ls.as_ref().get_lsps2_lsp_details())
-				{
-					if lsp_node_id == counterparty_node_id {
+					.map_or(false, |ls| ls.as_ref().is_lsps_node(&counterparty_node_id));
+				let allow_0conf =
+					self.config.trusted_peers_0conf.contains(&counterparty_node_id) || is_lsp_node;
+				let mut channel_override_config = None;
+				if let Some(ls) = self.liquidity_source.as_ref() {
+					if ls.as_ref().is_lsps_node(&counterparty_node_id) {
 						// When we're an LSPS2 client, allow claiming underpaying HTLCs as the LSP will skim off some fee. We'll
 						// check that they don't take too much before claiming.
 						//
@@ -1390,6 +1395,7 @@ where
 				if let Some(liquidity_source) = self.liquidity_source.as_ref() {
 					let skimmed_fee_msat = skimmed_fee_msat.unwrap_or(0);
 					liquidity_source
+						.lsps2_service()
 						.handle_payment_forwarded(Some(next_htlc.channel_id), skimmed_fee_msat)
 						.await;
 				}
@@ -1499,6 +1505,7 @@ where
 
 				if let Some(liquidity_source) = self.liquidity_source.as_ref() {
 					liquidity_source
+						.lsps2_service()
 						.handle_channel_ready(user_channel_id, &channel_id, &counterparty_node_id)
 						.await;
 				}
@@ -1570,6 +1577,7 @@ where
 			} => {
 				if let Some(liquidity_source) = self.liquidity_source.as_ref() {
 					liquidity_source
+						.lsps2_service()
 						.handle_htlc_intercepted(
 							requested_next_hop_scid,
 							intercept_id,

src/lib.rs

@@ -160,7 +160,7 @@ use lightning_background_processor::process_events_async;
 pub use lightning_invoice;
 pub use lightning_liquidity;
 pub use lightning_types;
-use liquidity::{LSPS1Liquidity, LiquiditySource};
+use liquidity::LiquiditySource;
 use lnurl_auth::LnurlAuth;
 use logger::{log_debug, log_error, log_info, log_trace, LdkLogger, Logger};
 use payment::asynchronous::om_mailbox::OnionMessageMailbox;
@@ -180,6 +180,7 @@ use types::{
 pub use types::{ChannelDetails, CustomTlvRecord, PeerDetails, SyncAndAsyncKVStore, UserChannelId};
 pub use vss_client;
 
+use crate::liquidity::Liquidity;
 use crate::scoring::setup_background_pathfinding_scores_sync;
 use crate::wallet::FundingAmount;
 
@@ -658,7 +659,51 @@ impl Node {
 			let mut stop_liquidity_handler = self.stop_sender.subscribe();
 			let liquidity_handler = Arc::clone(&liquidity_source);
 			let liquidity_logger = Arc::clone(&self.logger);
+			let discovery_ls = Arc::clone(&liquidity_source);
+			let discovery_cm = Arc::clone(&self.connection_manager);
 			self.runtime.spawn_background_task(async move {
+				let discovery_logger = Arc::clone(&liquidity_logger);
+				tokio::spawn(async move {
+					let mut set = tokio::task::JoinSet::new();
+					for (node_id, address) in discovery_ls.get_all_lsp_details() {
+						let cm = Arc::clone(&discovery_cm);
+						let logger = Arc::clone(&discovery_logger);
+						let ls = Arc::clone(&discovery_ls);
+						set.spawn(async move {
+							if let Err(e) =
+								cm.connect_peer_if_necessary(node_id, address.clone()).await
+							{
+								log_error!(
+									logger,
+									"Failed to connect to LSP {} for protocol discovery: {}",
+									node_id,
+									e
+								);
+								return;
+							}
+							match ls.discover_lsp_protocols(&node_id).await {
+								Ok(protocols) => {
+									log_info!(
+										logger,
+										"Discovered protocols for LSP {}: {:?}",
+										node_id,
+										protocols
+									);
+								},
+								Err(e) => {
+									log_error!(
+										logger,
+										"Failed to discover protocols for LSP {}: {:?}",
+										node_id,
+										e
+									);
+								},
+							}
+						});
+					}
+					while set.join_next().await.is_some() {}
+				});
+
 				loop {
 					tokio::select! {
 						_ = stop_liquidity_handler.changed() => {
@@ -1039,12 +1084,10 @@ impl Node {
 		})
 	}
 
-	/// Returns a liquidity handler allowing to request channels via the [bLIP-51 / LSPS1] protocol.
-	///
-	/// [bLIP-51 / LSPS1]: https://github.com/lightning/blips/blob/master/blip-0051.md
+	/// Returns a liquidity handler allowing to manage LSP connections and request channels.
 	#[cfg(not(feature = "uniffi"))]
-	pub fn lsps1_liquidity(&self) -> LSPS1Liquidity {
-		LSPS1Liquidity::new(
+	pub fn liquidity(&self) -> Liquidity {
+		Liquidity::new(
 			Arc::clone(&self.runtime),
 			Arc::clone(&self.wallet),
 			Arc::clone(&self.connection_manager),
@@ -1053,12 +1096,10 @@ impl Node {
 		)
 	}
 
-	/// Returns a liquidity handler allowing to request channels via the [bLIP-51 / LSPS1] protocol.
-	///
-	/// [bLIP-51 / LSPS1]: https://github.com/lightning/blips/blob/master/blip-0051.md
+	/// Returns a liquidity handler allowing to manage LSP connections and request channels.
 	#[cfg(feature = "uniffi")]
-	pub fn lsps1_liquidity(&self) -> Arc<LSPS1Liquidity> {
-		Arc::new(LSPS1Liquidity::new(
+	pub fn liquidity(&self) -> Arc<Liquidity> {
+		Arc::new(Liquidity::new(
 			Arc::clone(&self.runtime),
 			Arc::clone(&self.wallet),
 			Arc::clone(&self.connection_manager),