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

@@ -116,6 +116,7 @@ interface Builder {
 	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();
@@ -299,6 +300,8 @@ interface LSPS1Liquidity {
 	[Throws=NodeError]
 	LSPS1OrderStatus request_channel(u64 lsp_balance_sat, u64 client_balance_sat, u32 channel_expiry_blocks, boolean announce_channel);
 	[Throws=NodeError]
+	LSPS1OrderStatus request_channel_from_lsp(u64 lsp_balance_sat, u64 client_balance_sat, u32 channel_expiry_blocks, boolean announce_channel, PublicKey node_id);
+	[Throws=NodeError]
 	LSPS1OrderStatus check_order_status(LSPS1OrderId order_id);
 };
 

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::logger::{log_error, LdkLogger, LogLevel, LogWriter, Logger};
 use crate::message_handler::NodeCustomMessageHandler;
 use crate::payment::asynchronous::om_mailbox::OnionMessageMailbox;
@@ -119,10 +117,8 @@ 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>,
 }
@@ -401,17 +397,12 @@ impl NodeBuilder {
 	/// 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
+	#[deprecated(note = "Use `add_lsp` instead")]
+	#[allow(dead_code)]
 	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
+		self.add_lsp(node_id, address, token)
 	}
 
 	/// Configures the [`Node`] instance to source just-in-time inbound liquidity from the given
@@ -422,16 +413,32 @@ impl NodeBuilder {
 	/// 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
+	#[deprecated(note = "Use `add_lsp` instead")]
+	#[allow(dead_code)]
 	pub fn set_liquidity_source_lsps2(
 		&mut self, node_id: PublicKey, address: SocketAddress, token: Option<String>,
+	) -> &mut Self {
+		self.add_lsp(node_id, address, token)
+	}
+
+	/// 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.
+	/// 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
 	}
 
@@ -824,7 +831,7 @@ impl ArcedNodeBuilder {
 	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);
+		self.inner.write().unwrap().add_lsp(node_id, address, token);
 	}
 
 	/// Configures the [`Node`] instance to source just-in-time inbound liquidity from the given
@@ -838,7 +845,20 @@ impl ArcedNodeBuilder {
 	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);
+		self.inner.write().unwrap().add_lsp(node_id, address, token);
+	}
+
+	/// 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.
+	/// 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
@@ -1598,21 +1618,7 @@ 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(

src/event.rs

@@ -1221,12 +1221,8 @@ where
 				let user_channel_id: u128 = rng().random();
 				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
-					.liquidity_source
-					.as_ref()
-					.and_then(|ls| ls.as_ref().get_lsps2_lsp_details())
-				{
-					if lsp_node_id == counterparty_node_id {
+				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.
 						//

src/lib.rs

@@ -661,6 +661,29 @@ impl Node {
 			});
 		}
 
+		if let Some(liquidity_source) = self.liquidity_source.as_ref() {
+			let discovery_ls = Arc::clone(&liquidity_source);
+			let discovery_cm = Arc::clone(&self.connection_manager);
+			let discovery_logger = Arc::clone(&self.logger);
+			self.runtime.spawn_background_task(async move {
+				for (node_id, address) in discovery_ls.get_all_lsp_details() {
+					if let Err(e) =
+						discovery_cm.connect_peer_if_necessary(node_id, address.clone()).await
+					{
+						log_error!(
+							discovery_logger,
+							"Failed to connect to LSP {} for protocol discovery: {}",
+							node_id,
+							e
+						);
+						continue;
+					}
+				}
+
+				discovery_ls.discover_all_lsp_protocols().await;
+			});
+		}
+
 		log_info!(self.logger, "Startup complete.");
 		*is_running_lock = true;
 		Ok(())