Carry a configured fee claim into register_node

Bump the rust-lightning pin to 9b5f40f00, which brings the fee-claim
wire field, the LSP-side verifier, and the new register_node parameter.
That bump forces three coupled changes, so they land together.

Client side: LSPS4ClientConfig and the internal LSPS4Client now hold an
optional fee_claim, set_liquidity_source_lsps4 takes it as a third
argument, and lsps4_register_node relays it on every registration. mdkd
is the only caller, so widening the signature is contained. The value is
opaque here, a lowercase-hex signed grant that only the LSP decodes.

Service side: the bumped LdkLSPS4ServiceConfig grew an issuer_pubkeys
field with no Default, so the struct literal no longer compiles without
naming it. LSPS4ServiceConfig surfaces it; an empty Vec (the inert
default for a node acting only as a client) honours no claim and keeps
every peer on the standard policy.

With no claim configured the request carries None, the LSP resolves the
standard policy, and behaviour is unchanged.

Author: amackillop

Cargo.toml

@@ -42,17 +42,17 @@ default = []
 # lightning-macros = { version = "0.2.0" }
 
 # Branch: https://github.com/moneydevkit/rust-lightning/tree/lsp-0.2.0_accept-underpaying-htlcs_with_timing_logs
-lightning = { git = "https://github.com/moneydevkit/rust-lightning", rev = "f56f47fe6c874771cd079faaacf96c42b32fbe72", features = ["std"] }
-lightning-types = { git = "https://github.com/moneydevkit/rust-lightning", rev = "f56f47fe6c874771cd079faaacf96c42b32fbe72" }
-lightning-invoice = { git = "https://github.com/moneydevkit/rust-lightning", rev = "f56f47fe6c874771cd079faaacf96c42b32fbe72", features = ["std"] }
-lightning-net-tokio = { git = "https://github.com/moneydevkit/rust-lightning", rev = "f56f47fe6c874771cd079faaacf96c42b32fbe72", features = ["socks"] }
-lightning-persister = { git = "https://github.com/moneydevkit/rust-lightning", rev = "f56f47fe6c874771cd079faaacf96c42b32fbe72", features = ["tokio"] }
-lightning-background-processor = { git = "https://github.com/moneydevkit/rust-lightning", rev = "f56f47fe6c874771cd079faaacf96c42b32fbe72" }
-lightning-rapid-gossip-sync = { git = "https://github.com/moneydevkit/rust-lightning", rev = "f56f47fe6c874771cd079faaacf96c42b32fbe72" }
-lightning-block-sync = { git = "https://github.com/moneydevkit/rust-lightning", rev = "f56f47fe6c874771cd079faaacf96c42b32fbe72", features = ["rest-client", "rpc-client", "tokio"] }
-lightning-transaction-sync = { git = "https://github.com/moneydevkit/rust-lightning", rev = "f56f47fe6c874771cd079faaacf96c42b32fbe72", features = ["esplora-async-https", "time", "electrum-rustls-ring"] }
-lightning-liquidity = { git = "https://github.com/moneydevkit/rust-lightning", rev = "f56f47fe6c874771cd079faaacf96c42b32fbe72", features = ["std"] }
-lightning-macros = { git = "https://github.com/moneydevkit/rust-lightning", rev = "f56f47fe6c874771cd079faaacf96c42b32fbe72" }
+lightning = { git = "https://github.com/moneydevkit/rust-lightning", rev = "9b5f40f00a623ff5e1cbe2540d79c3665589be6e", features = ["std"] }
+lightning-types = { git = "https://github.com/moneydevkit/rust-lightning", rev = "9b5f40f00a623ff5e1cbe2540d79c3665589be6e" }
+lightning-invoice = { git = "https://github.com/moneydevkit/rust-lightning", rev = "9b5f40f00a623ff5e1cbe2540d79c3665589be6e", features = ["std"] }
+lightning-net-tokio = { git = "https://github.com/moneydevkit/rust-lightning", rev = "9b5f40f00a623ff5e1cbe2540d79c3665589be6e", features = ["socks"] }
+lightning-persister = { git = "https://github.com/moneydevkit/rust-lightning", rev = "9b5f40f00a623ff5e1cbe2540d79c3665589be6e", features = ["tokio"] }
+lightning-background-processor = { git = "https://github.com/moneydevkit/rust-lightning", rev = "9b5f40f00a623ff5e1cbe2540d79c3665589be6e" }
+lightning-rapid-gossip-sync = { git = "https://github.com/moneydevkit/rust-lightning", rev = "9b5f40f00a623ff5e1cbe2540d79c3665589be6e" }
+lightning-block-sync = { git = "https://github.com/moneydevkit/rust-lightning", rev = "9b5f40f00a623ff5e1cbe2540d79c3665589be6e", features = ["rest-client", "rpc-client", "tokio"] }
+lightning-transaction-sync = { git = "https://github.com/moneydevkit/rust-lightning", rev = "9b5f40f00a623ff5e1cbe2540d79c3665589be6e", features = ["esplora-async-https", "time", "electrum-rustls-ring"] }
+lightning-liquidity = { git = "https://github.com/moneydevkit/rust-lightning", rev = "9b5f40f00a623ff5e1cbe2540d79c3665589be6e", features = ["std"] }
+lightning-macros = { git = "https://github.com/moneydevkit/rust-lightning", rev = "9b5f40f00a623ff5e1cbe2540d79c3665589be6e" }
 
 #lightning = { path = "../rust-lightning/lightning", features = ["std"] }
 #lightning-types = { path = "../rust-lightning/lightning-types" }
@@ -101,7 +101,7 @@ winapi = { version = "0.3", features = ["winbase"] }
 [dev-dependencies]
 # lightning = { version = "0.2.0", features = ["std", "_test_utils"] }
 # Branch: https://github.com/moneydevkit/rust-lightning/commits/lsp-0.2.0_accept-underpaying-htlcs_with_timing_logs
-lightning = { git = "https://github.com/moneydevkit/rust-lightning", rev = "f56f47fe6c874771cd079faaacf96c42b32fbe72", features = ["std", "_test_utils"] }
+lightning = { git = "https://github.com/moneydevkit/rust-lightning", rev = "9b5f40f00a623ff5e1cbe2540d79c3665589be6e", features = ["std", "_test_utils"] }
 #lightning = { path = "../rust-lightning/lightning", features = ["std", "_test_utils"] }
 proptest = "1.0.0"
 regex = "1.5.6"

src/builder.rs

@@ -489,14 +489,14 @@ impl NodeBuilder {
 	///
 	/// Will mark the LSP as trusted for 0-confirmation channels, see [`Config::trusted_peers_0conf`].
 	pub fn set_liquidity_source_lsps4(
-		&mut self, node_id: PublicKey, address: SocketAddress,
+		&mut self, node_id: PublicKey, address: SocketAddress, fee_claim: 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 lsps4_client_config = LSPS4ClientConfig { node_id, address };
+		let lsps4_client_config = LSPS4ClientConfig { node_id, address, fee_claim };
 		liquidity_source_config.lsps4_client = Some(lsps4_client_config);
 		self
 	}
@@ -1873,7 +1873,11 @@ fn build_with_store_internal(
 			});
 
 			lsc.lsps4_client.as_ref().map(|config| {
-				liquidity_source_builder.lsps4_client(config.node_id, config.address.clone())
+				liquidity_source_builder.lsps4_client(
+					config.node_id,
+					config.address.clone(),
+					config.fee_claim.clone(),
+				)
 			});
 
 			let promise_secret = {
@@ -2152,7 +2156,34 @@ pub(crate) fn sanitize_alias(alias_str: &str) -> Result<NodeAlias, BuildError> {
 
 #[cfg(test)]
 mod tests {
-	use super::{sanitize_alias, BuildError, NodeAlias};
+	use super::{sanitize_alias, BuildError, NodeAlias, NodeBuilder};
+	use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
+	use lightning::ln::msgs::SocketAddress;
+
+	fn dummy_lsp() -> (PublicKey, SocketAddress) {
+		let node_id =
+			PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&[1u8; 32]).unwrap());
+		let address = SocketAddress::TcpIpV4 { addr: [127, 0, 0, 1], port: 9735 };
+		(node_id, address)
+	}
+
+	#[test]
+	fn lsps4_source_stores_the_fee_claim() {
+		let (node_id, address) = dummy_lsp();
+		let mut builder = NodeBuilder::new();
+		builder.set_liquidity_source_lsps4(node_id, address, Some("deadbeef".to_string()));
+		let config = builder.liquidity_source_config.unwrap().lsps4_client.unwrap();
+		assert_eq!(config.fee_claim, Some("deadbeef".to_string()));
+	}
+
+	#[test]
+	fn lsps4_source_without_a_claim_stores_none() {
+		let (node_id, address) = dummy_lsp();
+		let mut builder = NodeBuilder::new();
+		builder.set_liquidity_source_lsps4(node_id, address, None);
+		let config = builder.liquidity_source_config.unwrap().lsps4_client.unwrap();
+		assert_eq!(config.fee_claim, None);
+	}
 
 	#[test]
 	fn sanitize_empty_node_alias() {

src/liquidity.rs

@@ -13,7 +13,7 @@ use std::sync::{Arc, Mutex, RwLock};
 use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 
 use bitcoin::hashes::{sha256, Hash};
-use bitcoin::secp256k1::{PublicKey, Secp256k1};
+use bitcoin::secp256k1::{PublicKey, Secp256k1, XOnlyPublicKey};
 use bitcoin::Transaction;
 use chrono::Utc;
 use lightning::events::HTLCHandlingFailureType;
@@ -155,6 +155,7 @@ struct LSPS4Client {
 	lsp_node_id: PublicKey,
 	lsp_address: SocketAddress,
 	ldk_client_config: LdkLSPS4ClientConfig,
+	fee_claim: Option<String>,
 	pending_register_node_requests:
 		Mutex<HashMap<LSPSRequestId, oneshot::Sender<LSPS4RegisterNodeResponse>>>,
 }
@@ -163,6 +164,9 @@ struct LSPS4Client {
 pub(crate) struct LSPS4ClientConfig {
 	pub node_id: PublicKey,
 	pub address: SocketAddress,
+	/// Opaque lowercase-hex signed grant presented on `register_node`; the LSP verifies it against
+	/// its configured issuer keys. `None` leaves the node on the standard fee policy.
+	pub fee_claim: Option<String>,
 }
 struct LSPS4Service {
 	service_config: LSPS4ServiceConfig,
@@ -189,6 +193,10 @@ pub struct LSPS4ServiceConfig {
 	/// channels with the peer. The first entry applies when there are no channels, the second
 	/// when there is already one, and so on. If empty, no tiering is applied.
 	pub channel_size_tiers: Vec<u64>,
+	/// X-only public keys whose signatures grant a non-standard fee policy. A `register_node`
+	/// fee claim is honoured only if it verifies against one of these keys. Empty means no claim
+	/// is ever honoured and every peer stays on the standard policy.
+	pub issuer_pubkeys: Vec<XOnlyPublicKey>,
 }
 
 pub(crate) struct LiquiditySourceBuilder<L: Deref>
@@ -284,14 +292,15 @@ where
 	}
 
 	pub(crate) fn lsps4_client(
-		&mut self, lsp_node_id: PublicKey, lsp_address: SocketAddress,
+		&mut self, lsp_node_id: PublicKey, lsp_address: SocketAddress, fee_claim: Option<String>,
 	) -> &mut Self {
 		let ldk_client_config = LdkLSPS4ClientConfig {};
 		let pending_register_node_requests = Mutex::new(HashMap::new());
 		self.lsps4_client = Some(LSPS4Client {
 			lsp_node_id,
 			lsp_address,
 			ldk_client_config,
+			fee_claim,
 			pending_register_node_requests,
 		});
 		self
@@ -306,12 +315,12 @@ where
 	}
 
 	pub(crate) fn lsps4_service(&mut self, service_config: LSPS4ServiceConfig) -> &mut Self {
-		let ldk_service_config =
-			LdkLSPS4ServiceConfig { 
-				cltv_expiry_delta: LSPS2_CHANNEL_CLTV_EXPIRY_DELTA,
-				forwarding_fee_proportional_millionths: service_config
+		let ldk_service_config = LdkLSPS4ServiceConfig {
+			cltv_expiry_delta: LSPS2_CHANNEL_CLTV_EXPIRY_DELTA,
+			forwarding_fee_proportional_millionths: service_config
 				.forwarding_fee_proportional_millionths,
-			};
+			issuer_pubkeys: service_config.issuer_pubkeys.clone(),
+		};
 		self.lsps4_service = Some(LSPS4Service { service_config, ldk_service_config });
 		self
 	}
@@ -1684,7 +1693,9 @@ where
 		{
 			let mut pending_register_node_requests_lock =
 				lsps4_client.pending_register_node_requests.lock().unwrap();
-			let request_id = client_handler.register_node(lsps4_client.lsp_node_id).unwrap();
+			let request_id = client_handler
+				.register_node(lsps4_client.lsp_node_id, lsps4_client.fee_claim.clone())
+				.unwrap();
 			pending_register_node_requests_lock.insert(request_id, register_node_sender);
 		}
 		log_info!(self.logger, "TIMING: lsps4_register_node() sent request, waiting for response...");