Allow configuring LSPS2 service via builders

We add the capability to configure LSPS2 service mode in `Builder` and
`LiquiditySourceBuilder`.

Author: tnull

src/builder.rs

@@ -74,6 +74,7 @@ use vss_client::headers::{FixedHeaders, LnurlAuthToJwtProvider, VssHeaderProvide
 
 const VSS_HARDENED_CHILD_INDEX: u32 = 877;
 const VSS_LNURL_AUTH_HARDENED_CHILD_INDEX: u32 = 138;
+const LSPS_HARDENED_CHILD_INDEX: u32 = 577;
 
 #[derive(Debug, Clone)]
 enum ChainDataSourceConfig {
@@ -100,6 +101,8 @@ struct LiquiditySourceConfig {
 	lsps1_client: Option<LSPS1ClientConfig>,
 	// Act as an LSPS2 client connecting to the given service.
 	lsps2_client: Option<LSPS2ClientConfig>,
+	// Act as an LSPS2 service.
+	lsps2_service: Option<LSPS2ServiceConfig>,
 }
 
 #[derive(Debug, Clone)]
@@ -116,6 +119,12 @@ struct LSPS2ClientConfig {
 	token: Option<String>,
 }
 
+#[derive(Debug, Clone)]
+struct LSPS2ServiceConfig {
+	token: Option<String>,
+	advertise_service: bool,
+}
+
 /// An error encountered during building a [`Node`].
 ///
 /// [`Node`]: crate::Node
@@ -323,6 +332,26 @@ impl NodeBuilder {
 		self
 	}
 
+	/// Configures the [`Node`] instance to provide an [LSPS2] service, issuing just-in-time
+	/// channels to clients.
+	///
+	/// If a `token` is provided, only requests matching this token will be accepted.
+	///
+	/// If `advertise_service` is set, the LSPS service will be announced via the gossip network.
+	///
+	/// **Caution**: LSP service support is in **alpha** and is considered an experimental feature.
+	///
+	/// [LSPS2]: https://github.com/BitcoinAndLightningLayerSpecs/lsp/blob/main/LSPS2/README.md
+	pub fn set_liquidity_provider_lsps2(
+		&mut self, token: Option<String>, advertise_service: bool,
+	) -> &mut Self {
+		let liquidity_source_config =
+			self.liquidity_source_config.get_or_insert(LiquiditySourceConfig::default());
+		let lsps2_service_config = LSPS2ServiceConfig { token, advertise_service };
+		liquidity_source_config.lsps2_service = Some(lsps2_service_config);
+		self
+	}
+
 	/// Sets the used storage directory path.
 	pub fn set_storage_dir_path(&mut self, storage_dir_path: String) -> &mut Self {
 		self.config.storage_dir_path = storage_dir_path;
@@ -658,6 +687,20 @@ impl ArcedNodeBuilder {
 		self.inner.write().unwrap().set_liquidity_source_lsps2(node_id, address, token);
 	}
 
+	/// Configures the [`Node`] instance to provide an [LSPS2] service, issuing just-in-time
+	/// channels to clients.
+	///
+	/// If a `token` is provided, only requests matching this token will be accepted.
+	///
+	/// If `advertise_service` is set, the LSPS service will be announced via the gossip network.
+	///
+	/// **Caution**: LSP service support is in **alpha** and is considered an experimental feature.
+	///
+	/// [LSPS2]: https://github.com/BitcoinAndLightningLayerSpecs/lsp/blob/main/LSPS2/README.md
+	pub fn set_liquidity_provider_lsps2(&self, token: Option<String>) {
+		self.inner.write().unwrap().set_liquidity_service_lsps2(token);
+	}
+
 	/// Sets the used storage directory path.
 	pub fn set_storage_dir_path(&self, storage_dir_path: String) {
 		self.inner.write().unwrap().set_storage_dir_path(storage_dir_path);
@@ -1105,39 +1148,56 @@ fn build_with_store_internal(
 		},
 	};
 
-	let liquidity_source = liquidity_source_config.as_ref().map(|lsc| {
-		let mut liquidity_source_builder = LiquiditySourceBuilder::new(
-			Arc::clone(&channel_manager),
-			Arc::clone(&keys_manager),
-			Arc::clone(&chain_source),
-			Arc::clone(&config),
-			Arc::clone(&logger),
-		);
+	let (liquidity_source, custom_message_handler) =
+		if let Some(lsc) = liquidity_source_config.as_ref() {
+			let mut liquidity_source_builder = LiquiditySourceBuilder::new(
+				Arc::clone(&channel_manager),
+				Arc::clone(&keys_manager),
+				Arc::clone(&chain_source),
+				Arc::clone(&config),
+				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.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(),
-			)
-		});
+			lsc.lsps2_client.as_ref().map(|config| {
+				liquidity_source_builder.lsps2_client(
+					config.node_id,
+					config.address.clone(),
+					config.token.clone(),
+				)
+			});
 
-		Arc::new(liquidity_source_builder.build())
-	});
+			let promise_secret = {
+				let lsps_xpriv = derive_xprv(
+					Arc::clone(&config),
+					&seed_bytes,
+					LSPS_HARDENED_CHILD_INDEX,
+					Arc::clone(&logger),
+				)?;
+				lsps_xpriv.private_key.secret_bytes()
+			};
+			lsc.lsps2_service.as_ref().map(|config| {
+				liquidity_source_builder.lsps2_service(
+					promise_secret,
+					config.token.clone(),
+					config.advertise_service,
+				)
+			});
 
-	let custom_message_handler = if let Some(liquidity_source) = liquidity_source.as_ref() {
-		Arc::new(NodeCustomMessageHandler::new_liquidity(Arc::clone(&liquidity_source)))
-	} else {
-		Arc::new(NodeCustomMessageHandler::new_ignoring())
-	};
+			let liquidity_source = Arc::new(liquidity_source_builder.build());
+			let custom_message_handler =
+				Arc::new(NodeCustomMessageHandler::new_liquidity(Arc::clone(&liquidity_source)));
+			(Some(liquidity_source), custom_message_handler)
+		} else {
+			(None, Arc::new(NodeCustomMessageHandler::new_ignoring()))
+		};
 
 	let msg_handler = match gossip_source.as_gossip_sync() {
 		GossipSync::P2P(p2p_gossip_sync) => MessageHandler {

src/liquidity.rs

@@ -27,8 +27,9 @@ use lightning_liquidity::lsps1::msgs::{
 use lightning_liquidity::lsps2::client::LSPS2ClientConfig;
 use lightning_liquidity::lsps2::event::LSPS2ClientEvent;
 use lightning_liquidity::lsps2::msgs::OpeningFeeParams;
+use lightning_liquidity::lsps2::service::LSPS2ServiceConfig;
 use lightning_liquidity::lsps2::utils::compute_opening_fee;
-use lightning_liquidity::LiquidityClientConfig;
+use lightning_liquidity::{LiquidityClientConfig, LiquidityServiceConfig};
 
 use bitcoin::hashes::{sha256, Hash};
 use bitcoin::secp256k1::{PublicKey, Secp256k1};
@@ -65,12 +66,19 @@ struct LSPS2Client {
 	pending_buy_requests: Mutex<HashMap<RequestId, oneshot::Sender<LSPS2BuyResponse>>>,
 }
 
+struct LSPS2Service {
+	token: Option<String>,
+	service_config: LSPS2ServiceConfig,
+	advertise_service: bool,
+}
+
 pub(crate) struct LiquiditySourceBuilder<L: Deref>
 where
 	L::Target: Logger,
 {
 	lsps1_client: Option<LSPS1Client>,
 	lsps2_client: Option<LSPS2Client>,
+	lsps2_service: Option<LSPS2Service>,
 	channel_manager: Arc<ChannelManager>,
 	keys_manager: Arc<KeysManager>,
 	chain_source: Arc<ChainSource>,
@@ -88,9 +96,11 @@ where
 	) -> Self {
 		let lsps1_client = None;
 		let lsps2_client = None;
+		let lsps2_service = None;
 		Self {
 			lsps1_client,
 			lsps2_client,
+			lsps2_service,
 			channel_manager,
 			keys_manager,
 			chain_source,
@@ -136,7 +146,21 @@ where
 		self
 	}
 
+	pub(crate) fn lsps2_service(
+		&mut self, promise_secret: [u8; 32], token: Option<String>, advertise_service: bool,
+	) -> &mut Self {
+		let service_config = LSPS2ServiceConfig { promise_secret };
+		self.lsps2_service = Some(LSPS2Service { token, service_config, advertise_service });
+		self
+	}
+
 	pub(crate) fn build(self) -> LiquiditySource<L> {
+		let liquidity_service_config = self.lsps2_service.as_ref().map(|s| {
+			let lsps2_service_config = Some(s.service_config.clone());
+			let advertise_service = s.advertise_service;
+			LiquidityServiceConfig { lsps2_service_config, advertise_service }
+		});
+
 		let lsps1_client_config = self.lsps1_client.as_ref().map(|s| s.client_config.clone());
 		let lsps2_client_config = self.lsps2_client.as_ref().map(|s| s.client_config.clone());
 		let liquidity_client_config =
@@ -147,13 +171,14 @@ where
 			Arc::clone(&self.channel_manager),
 			Some(Arc::clone(&self.chain_source)),
 			None,
-			None,
+			liquidity_service_config,
 			liquidity_client_config,
 		));
 
 		LiquiditySource {
 			lsps1_client: self.lsps1_client,
 			lsps2_client: self.lsps2_client,
+			lsps2_service: self.lsps2_service,
 			channel_manager: self.channel_manager,
 			keys_manager: self.keys_manager,
 			liquidity_manager,
@@ -169,6 +194,7 @@ where
 {
 	lsps1_client: Option<LSPS1Client>,
 	lsps2_client: Option<LSPS2Client>,
+	lsps2_service: Option<LSPS2Service>,
 	channel_manager: Arc<ChannelManager>,
 	keys_manager: Arc<KeysManager>,
 	liquidity_manager: Arc<LiquidityManager>,