Support LSPS2 metadata in BOLT12 payment context

Encode LSPS2 parameters in a shared payment metadata type so both BOLT11 invoices and BOLT12 payment contexts can carry the fee limits needed when handling intercepted payments.

Co-Authored-By: HAL 9000

Author: tnull

src/event.rs

@@ -7,7 +7,7 @@
 
 use core::future::Future;
 use core::task::{Poll, Waker};
-use std::collections::VecDeque;
+use std::collections::{BTreeMap, VecDeque};
 use std::ops::Deref;
 use std::sync::{Arc, Mutex};
 
@@ -50,7 +50,7 @@ use crate::payment::asynchronous::static_invoice_store::StaticInvoiceStore;
 use crate::payment::store::{
 	PaymentDetails, PaymentDetailsUpdate, PaymentDirection, PaymentKind, PaymentStatus,
 };
-use crate::payment::PaymentMetadata;
+use crate::payment::{PaymentMetadata, LDK_NODE_BOLT12_PAYMENT_METADATA_KEY};
 use crate::runtime::Runtime;
 use crate::types::{
 	CustomTlvRecord, DynStore, KeysManager, OnionMessenger, PaymentStore, Sweeper, Wallet,
@@ -600,8 +600,9 @@ where
 		}
 	}
 
-	fn lsps2_max_total_opening_fee_msat(payment_metadata: &[u8], amount_msat: u64) -> Option<u64> {
-		let metadata = PaymentMetadata::read(&mut &payment_metadata[..]).ok()?;
+	fn lsps2_max_total_opening_fee_msat_from_metadata(
+		metadata: PaymentMetadata, amount_msat: u64,
+	) -> Option<u64> {
 		let lsps2_parameters = metadata.lsps2_parameters?;
 		lsps2_parameters.max_total_opening_fee_msat.or_else(|| {
 			lsps2_parameters.max_proportional_opening_fee_ppm_msat.and_then(|max_prop_fee| {
@@ -611,6 +612,19 @@ where
 		})
 	}
 
+	fn lsps2_max_total_opening_fee_msat(payment_metadata: &[u8], amount_msat: u64) -> Option<u64> {
+		let metadata = PaymentMetadata::read(&mut &payment_metadata[..]).ok()?;
+		Self::lsps2_max_total_opening_fee_msat_from_metadata(metadata, amount_msat)
+	}
+
+	fn lsps2_max_total_opening_fee_msat_from_bolt12_metadata(
+		payment_metadata: Option<&BTreeMap<u64, Vec<u8>>>, amount_msat: u64,
+	) -> Option<u64> {
+		let encoded_metadata = payment_metadata?.get(&LDK_NODE_BOLT12_PAYMENT_METADATA_KEY)?;
+		let metadata = PaymentMetadata::read(&mut &encoded_metadata[..]).ok()?;
+		Self::lsps2_max_total_opening_fee_msat_from_metadata(metadata, amount_msat)
+	}
+
 	pub async fn handle_event(&self, event: LdkEvent) -> Result<(), ReplayEvent> {
 		match event {
 			LdkEvent::FundingGenerationReady {
@@ -799,13 +813,19 @@ where
 							.and_then(|metadata| {
 								Self::lsps2_max_total_opening_fee_msat(metadata, amount_msat)
 							}),
+						PaymentPurpose::Bolt12OfferPayment { payment_context, .. } => {
+							Self::lsps2_max_total_opening_fee_msat_from_bolt12_metadata(
+								payment_context.payment_metadata.as_ref(),
+								amount_msat,
+							)
+						},
 						_ => None,
 					};
 
 					let Some(max_total_opening_fee_msat) = max_total_opening_fee_msat else {
 						log_info!(
 							self.logger,
-							"Refusing inbound payment with hash {} as the counterparty withheld {}msat without valid BOLT11 LSPS2 payment metadata",
+							"Refusing inbound payment with hash {} as the counterparty withheld {}msat without valid LSPS2 payment metadata",
 							hex_utils::to_string(&payment_hash.0),
 							counterparty_skimmed_fee_msat,
 						);
@@ -829,18 +849,24 @@ where
 						match &info.kind {
 							PaymentKind::Bolt11 { .. } => {
 								let update = PaymentDetailsUpdate {
-									counterparty_skimmed_fee_msat: Some(Some(counterparty_skimmed_fee_msat)),
+									counterparty_skimmed_fee_msat: Some(Some(
+										counterparty_skimmed_fee_msat,
+									)),
 									..PaymentDetailsUpdate::new(payment_id)
 								};
 								match self.payment_store.update(update).await {
 									Ok(_) => (),
 									Err(e) => {
-										log_error!(self.logger, "Failed to access payment store: {}", e);
+										log_error!(
+											self.logger,
+											"Failed to access payment store: {}",
+											e
+										);
 										return Err(ReplayEvent());
 									},
 								};
 							},
-							_ => debug_assert!(false, "We only expect the counterparty to get away with withholding fees for BOLT11 payments."),
+							_ => {},
 						}
 					}
 				}
@@ -1936,6 +1962,7 @@ mod tests {
 				max_total_opening_fee_msat: Some(42_000),
 				max_proportional_opening_fee_ppm_msat: None,
 			}),
+			lsps2_bolt12_invoice_parameters: None,
 		};
 
 		assert_eq!(
@@ -1947,14 +1974,37 @@ mod tests {
 		);
 	}
 
+	#[test]
+	fn lsps2_bolt12_payment_metadata_decodes_total_fee_limit() {
+		let metadata = PaymentMetadata {
+			lsps2_parameters: Some(LSPS2Parameters {
+				max_total_opening_fee_msat: None,
+				max_proportional_opening_fee_ppm_msat: Some(10_000),
+			}),
+			lsps2_bolt12_invoice_parameters: None,
+		}
+		.encode_as_bolt12_payment_metadata();
+
+		assert_eq!(
+			EventHandler::<Arc<TestLogger>>::lsps2_max_total_opening_fee_msat_from_bolt12_metadata(
+				Some(&metadata),
+				100_000
+			),
+			Some(1_000)
+		);
+	}
+
 	#[test]
 	fn lsps2_payment_metadata_missing_or_malformed_limit_is_rejected() {
-		let empty_metadata = PaymentMetadata { lsps2_parameters: None }.encode();
+		let empty_metadata =
+			PaymentMetadata { lsps2_parameters: None, lsps2_bolt12_invoice_parameters: None }
+				.encode();
 		let metadata_without_fee_limit = PaymentMetadata {
 			lsps2_parameters: Some(LSPS2Parameters {
 				max_total_opening_fee_msat: None,
 				max_proportional_opening_fee_ppm_msat: None,
 			}),
+			lsps2_bolt12_invoice_parameters: None,
 		}
 		.encode();
 

src/payment/bolt11.rs

@@ -13,7 +13,6 @@ use std::sync::{Arc, RwLock};
 
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::hashes::Hash;
-use lightning::impl_ser_tlv_based;
 use lightning::ln::channelmanager::{
 	Bolt11InvoiceParameters, OptionalBolt11PaymentParams, PaymentId,
 };
@@ -32,8 +31,7 @@ use crate::ffi::{maybe_deref, maybe_try_convert_enum, maybe_wrap};
 use crate::liquidity::LiquiditySource;
 use crate::logger::{log_error, log_info, LdkLogger, Logger};
 use crate::payment::store::{
-	LSPS2Parameters, PaymentDetails, PaymentDetailsUpdate, PaymentDirection, PaymentKind,
-	PaymentStatus,
+	PaymentDetails, PaymentDetailsUpdate, PaymentDirection, PaymentKind, PaymentStatus,
 };
 use crate::peer_store::{PeerInfo, PeerStore};
 use crate::runtime::Runtime;
@@ -49,16 +47,6 @@ type Bolt11InvoiceDescription = LdkBolt11InvoiceDescription;
 #[cfg(feature = "uniffi")]
 type Bolt11InvoiceDescription = crate::ffi::Bolt11InvoiceDescription;
 
-/// Metadata carried in BOLT11 invoice `payment_metadata`.
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub(crate) struct PaymentMetadata {
-	pub(crate) lsps2_parameters: Option<LSPS2Parameters>,
-}
-
-impl_ser_tlv_based!(PaymentMetadata, {
-	(0, lsps2_parameters, option),
-});
-
 /// A payment handler allowing to create and pay [BOLT 11] invoices.
 ///
 /// Should be retrieved by calling [`Node::bolt11_payment`].
@@ -248,37 +236,6 @@ impl Bolt11Payment {
 	}
 }
 
-#[cfg(test)]
-mod tests {
-	use lightning::util::ser::{Readable, Writeable};
-
-	use super::*;
-
-	#[test]
-	fn empty_metadata_roundtrips() {
-		let metadata = PaymentMetadata { lsps2_parameters: None };
-
-		let encoded = metadata.encode();
-		let decoded = PaymentMetadata::read(&mut &*encoded).unwrap();
-
-		assert_eq!(metadata, decoded);
-	}
-
-	#[test]
-	fn lsps2_parameters_roundtrip() {
-		let lsps2_parameters = LSPS2Parameters {
-			max_total_opening_fee_msat: Some(42_000),
-			max_proportional_opening_fee_ppm_msat: Some(17_000),
-		};
-		let metadata = PaymentMetadata { lsps2_parameters: Some(lsps2_parameters) };
-
-		let encoded = metadata.encode();
-		let decoded = PaymentMetadata::read(&mut &*encoded).unwrap();
-
-		assert_eq!(metadata, decoded);
-	}
-}
-
 #[cfg_attr(feature = "uniffi", uniffi::export)]
 impl Bolt11Payment {
 	/// Send a payment given an invoice.

src/payment/metadata.rs

@@ -0,0 +1,111 @@
+use std::collections::BTreeMap;
+
+use lightning::impl_ser_tlv_based;
+use lightning::util::ser::{Readable, Writeable};
+use lightning_liquidity::lsps2::router::{
+	LSPS2Bolt12InvoiceParameters, LSPS2Bolt12PaymentMetadataDecoder,
+};
+
+use crate::payment::store::LSPS2Parameters;
+
+pub(crate) const LDK_NODE_BOLT12_PAYMENT_METADATA_KEY: u64 = 0;
+
+/// Metadata carried in BOLT11 invoice `payment_metadata` or BOLT12 payment metadata maps.
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub(crate) struct PaymentMetadata {
+	pub(crate) lsps2_parameters: Option<LSPS2Parameters>,
+	pub(crate) lsps2_bolt12_invoice_parameters: Option<LSPS2Bolt12InvoiceParameters>,
+}
+
+impl PaymentMetadata {
+	pub(crate) fn encode_as_bolt12_payment_metadata(&self) -> BTreeMap<u64, Vec<u8>> {
+		let mut metadata = BTreeMap::new();
+		metadata.insert(LDK_NODE_BOLT12_PAYMENT_METADATA_KEY, self.encode());
+		metadata
+	}
+}
+
+impl_ser_tlv_based!(PaymentMetadata, {
+	(0, lsps2_parameters, option),
+	(2, lsps2_bolt12_invoice_parameters, option),
+});
+
+#[derive(Clone, Copy)]
+pub(crate) struct LdkNodeLSPS2Bolt12PaymentMetadataDecoder;
+
+impl LSPS2Bolt12PaymentMetadataDecoder for LdkNodeLSPS2Bolt12PaymentMetadataDecoder {
+	fn decode_lsps2_invoice_parameters(
+		&self, payment_metadata: &BTreeMap<u64, Vec<u8>>,
+	) -> Vec<LSPS2Bolt12InvoiceParameters> {
+		payment_metadata
+			.get(&LDK_NODE_BOLT12_PAYMENT_METADATA_KEY)
+			.and_then(|encoded| PaymentMetadata::read(&mut &encoded[..]).ok())
+			.and_then(|metadata| metadata.lsps2_bolt12_invoice_parameters)
+			.into_iter()
+			.collect()
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
+	use lightning::util::ser::{Readable, Writeable};
+
+	use super::*;
+
+	fn pubkey(byte: u8) -> PublicKey {
+		PublicKey::from_secret_key(&Secp256k1::new(), &SecretKey::from_slice(&[byte; 32]).unwrap())
+	}
+
+	#[test]
+	fn empty_metadata_roundtrips() {
+		let metadata =
+			PaymentMetadata { lsps2_parameters: None, lsps2_bolt12_invoice_parameters: None };
+
+		let encoded = metadata.encode();
+		let decoded = PaymentMetadata::read(&mut &*encoded).unwrap();
+
+		assert_eq!(metadata, decoded);
+	}
+
+	#[test]
+	fn lsps2_parameters_roundtrip() {
+		let lsps2_parameters = LSPS2Parameters {
+			max_total_opening_fee_msat: Some(42_000),
+			max_proportional_opening_fee_ppm_msat: Some(17_000),
+		};
+		let lsps2_bolt12_invoice_parameters = LSPS2Bolt12InvoiceParameters {
+			counterparty_node_id: pubkey(2),
+			intercept_scid: 42,
+			cltv_expiry_delta: 144,
+		};
+		let metadata = PaymentMetadata {
+			lsps2_parameters: Some(lsps2_parameters),
+			lsps2_bolt12_invoice_parameters: Some(lsps2_bolt12_invoice_parameters),
+		};
+
+		let encoded = metadata.encode();
+		let decoded = PaymentMetadata::read(&mut &*encoded).unwrap();
+
+		assert_eq!(metadata, decoded);
+	}
+
+	#[test]
+	fn bolt12_metadata_decoder_extracts_invoice_parameters() {
+		let lsps2_bolt12_invoice_parameters = LSPS2Bolt12InvoiceParameters {
+			counterparty_node_id: pubkey(3),
+			intercept_scid: 43,
+			cltv_expiry_delta: 72,
+		};
+		let metadata = PaymentMetadata {
+			lsps2_parameters: None,
+			lsps2_bolt12_invoice_parameters: Some(lsps2_bolt12_invoice_parameters),
+		}
+		.encode_as_bolt12_payment_metadata();
+
+		let decoded =
+			LdkNodeLSPS2Bolt12PaymentMetadataDecoder.decode_lsps2_invoice_parameters(&metadata);
+
+		assert_eq!(decoded, vec![lsps2_bolt12_invoice_parameters]);
+	}
+}

src/payment/mod.rs

@@ -10,15 +10,18 @@
 pub(crate) mod asynchronous;
 mod bolt11;
 mod bolt12;
+mod metadata;
 mod onchain;
 pub(crate) mod pending_payment_store;
 mod spontaneous;
 pub(crate) mod store;
 mod unified;
 
 pub use bolt11::Bolt11Payment;
-pub(crate) use bolt11::PaymentMetadata;
 pub use bolt12::Bolt12Payment;
+pub(crate) use metadata::{
+	LdkNodeLSPS2Bolt12PaymentMetadataDecoder, PaymentMetadata, LDK_NODE_BOLT12_PAYMENT_METADATA_KEY,
+};
 pub use onchain::OnchainPayment;
 pub use pending_payment_store::PendingPaymentDetails;
 pub use spontaneous::SpontaneousPayment;