Review: Support Currency-Based Offers and Async Invoice Handling via FlowEvents

fuzz/src/invoice_request_deser.rs

@@ -17,8 +17,10 @@ use lightning::blinded_path::payment::{
 use lightning::ln::channelmanager::MIN_FINAL_CLTV_EXPIRY_DELTA;
 use lightning::ln::inbound_payment::ExpandedKey;
 use lightning::offers::invoice::UnsignedBolt12Invoice;
-use lightning::offers::invoice_request::{InvoiceRequest, InvoiceRequestFields};
-use lightning::offers::offer::OfferId;
+use lightning::offers::invoice_request::{
+	CurrencyConversion, InvoiceRequest, InvoiceRequestFields,
+};
+use lightning::offers::offer::{CurrencyCode, OfferId};
 use lightning::offers::parse::Bolt12SemanticError;
 use lightning::sign::{EntropySource, ReceiveAuthKey};
 use lightning::types::features::BlindedHopFeatures;
@@ -78,6 +80,14 @@ fn privkey(byte: u8) -> SecretKey {
 	SecretKey::from_slice(&[byte; 32]).unwrap()
 }
 
+struct FuzzCurrencyConversion;
+
+impl CurrencyConversion for FuzzCurrencyConversion {
+	fn fiat_to_msats(&self, _iso4217_code: CurrencyCode) -> Result<u64, ()> {
+		unreachable!()
+	}
+}
+
 fn build_response<T: secp256k1::Signing + secp256k1::Verification>(
 	invoice_request: &InvoiceRequest, secp_ctx: &Secp256k1<T>,
 ) -> Result<UnsignedBolt12Invoice, Bolt12SemanticError> {
@@ -144,7 +154,7 @@ fn build_response<T: secp256k1::Signing + secp256k1::Verification>(
 	.unwrap();
 
 	let payment_hash = PaymentHash([42; 32]);
-	invoice_request.respond_with(vec![payment_path], payment_hash)?.build()
+	invoice_request.respond_with(&FuzzCurrencyConversion, vec![payment_path], payment_hash)?.build()
 }
 
 pub fn invoice_request_deser_test<Out: test_logger::Output>(data: &[u8], out: Out) {

lightning/src/ln/channelmanager.rs

@@ -93,9 +93,11 @@ use crate::offers::async_receive_offer_cache::AsyncReceiveOfferCache;
 use crate::offers::flow::{HeldHtlcReplyPath, InvreqResponseInstructions, OffersMessageFlow};
 use crate::offers::invoice::{Bolt12Invoice, UnsignedBolt12Invoice};
 use crate::offers::invoice_error::InvoiceError;
-use crate::offers::invoice_request::{InvoiceRequest, InvoiceRequestVerifiedFromOffer};
+use crate::offers::invoice_request::{
+	DefaultCurrencyConversion, InvoiceRequest, InvoiceRequestVerifiedFromOffer,
+};
 use crate::offers::nonce::Nonce;
-use crate::offers::offer::{Offer, OfferFromHrn};
+use crate::offers::offer::{Amount, Offer, OfferFromHrn};
 use crate::offers::parse::Bolt12SemanticError;
 use crate::offers::refund::Refund;
 use crate::offers::static_invoice::StaticInvoice;
@@ -2664,6 +2666,9 @@ pub struct ChannelManager<
 	fee_estimator: LowerBoundedFeeEstimator<F>,
 	chain_monitor: M,
 	tx_broadcaster: T,
+	#[cfg(test)]
+	pub(super) router: R,
+	#[cfg(not(test))]
 	router: R,
 
 	#[cfg(test)]
@@ -2890,6 +2895,9 @@ pub struct ChannelManager<
 	pub(super) entropy_source: ES,
 	#[cfg(not(test))]
 	entropy_source: ES,
+	#[cfg(test)]
+	pub(super) node_signer: NS,
+	#[cfg(not(test))]
 	node_signer: NS,
 	#[cfg(test)]
 	pub(super) signer_provider: SP,
@@ -3945,7 +3953,8 @@ where
 		let flow = OffersMessageFlow::new(
 			ChainHash::using_genesis_block(params.network), params.best_block,
 			our_network_pubkey, current_timestamp, expanded_inbound_key,
-			node_signer.get_receive_auth_key(), secp_ctx.clone(), message_router, logger.clone(),
+			node_signer.get_receive_auth_key(), secp_ctx.clone(), message_router, false,
+			logger.clone(),
 		);
 
 		ChannelManager {
@@ -5666,6 +5675,7 @@ where
 			let features = self.bolt12_invoice_features();
 			let outbound_pmts_res = self.pending_outbound_payments.static_invoice_received(
 				invoice,
+				&DefaultCurrencyConversion,
 				payment_id,
 				features,
 				best_block_height,
@@ -12935,12 +12945,21 @@ where
 	/// Uses [`InvoiceRequestBuilder`] such that the [`InvoiceRequest`] it builds is recognized by
 	/// the [`ChannelManager`] when handling a [`Bolt12Invoice`] message in response to the request.
 	///
-	/// `amount_msats` allows you to overpay what is required to satisfy the offer, or may be
-	/// required if the offer does not require a specific amount.
-	///
 	/// If the [`Offer`] was built from a human readable name resolved using BIP 353, you *must*
 	/// instead call [`Self::pay_for_offer_from_hrn`].
 	///
+	/// # Amount
+	///	`amount_msats` allows you to overpay what is required to satisfy the offer, or may be
+	/// required if the offer does not require a specific amount.
+	///
+	/// # Currency
+	///
+	/// If the [`Offer`] specifies its amount in a currency (that is, [`Amount::Currency`]), callers
+	/// must provide the `amount_msats`. [`ChannelManager`] enforces only that an amount is present
+	/// in this case. It does not verify here that the provided `amount_msats` is sufficient once
+	/// converted from the currency amount. The recipient may reject the resulting [`InvoiceRequest`]
+	/// if the amount is insufficient after conversion.
+	///
 	/// # Payment
 	///
 	/// The provided `payment_id` is used to ensure that only one invoice is paid for the request
@@ -13078,6 +13097,13 @@ where
 		let entropy = &*self.entropy_source;
 		let nonce = Nonce::from_entropy_source(entropy);
 
+		// If the offer is for a specific currency, ensure the amount is provided.
+		if let Some(Amount::Currency { iso4217_code: _, amount: _ }) = offer.amount() {
+			if amount_msats.is_none() {
+				return Err(Bolt12SemanticError::MissingAmount);
+			}
+		}
+
 		let builder = self.flow.create_invoice_request_builder(
 			offer, nonce, payment_id,
 		)?;
@@ -13160,7 +13186,20 @@ where
 
 		let invoice = builder.allow_mpp().build_and_sign(secp_ctx)?;
 
-		self.flow.enqueue_invoice(invoice.clone(), refund, self.get_peers_for_blinded_path())?;
+		if refund.paths().is_empty() {
+			self.flow.enqueue_invoice_using_node_id(
+				invoice.clone(),
+				refund.payer_signing_pubkey(),
+				self.get_peers_for_blinded_path(),
+			)?;
+		} else {
+			self.flow.enqueue_invoice_using_reply_paths(
+				invoice.clone(),
+				refund.paths(),
+				self.get_peers_for_blinded_path(),
+			)?;
+		}
+
 		Ok(invoice)
 	}
 
@@ -13383,7 +13422,7 @@ where
 		now
 	}
 
-	fn get_peers_for_blinded_path(&self) -> Vec<MessageForwardNode> {
+	pub(crate) fn get_peers_for_blinded_path(&self) -> Vec<MessageForwardNode> {
 		let per_peer_state = self.per_peer_state.read().unwrap();
 		per_peer_state
 			.iter()
@@ -15296,7 +15335,7 @@ where
 					None => return None,
 				};
 
-				let invoice_request = match self.flow.verify_invoice_request(invoice_request, context) {
+				let invoice_request = match self.flow.verify_invoice_request(invoice_request, context, responder.clone()) {
 					Ok(InvreqResponseInstructions::SendInvoice(invoice_request)) => invoice_request,
 					Ok(InvreqResponseInstructions::SendStaticInvoice { recipient_id, invoice_slot, invoice_request }) => {
 						self.pending_events.lock().unwrap().push_back((Event::StaticInvoiceRequested {
@@ -15305,6 +15344,7 @@ where
 
 						return None
 					},
+					Ok(InvreqResponseInstructions::AsynchronouslyHandleResponse) => return None,
 					Err(_) => return None,
 				};
 
@@ -15320,6 +15360,7 @@ where
 					InvoiceRequestVerifiedFromOffer::DerivedKeys(request) => {
 						let result = self.flow.create_invoice_builder_from_invoice_request_with_keys(
 							&self.router,
+							&DefaultCurrencyConversion,
 							&request,
 							self.list_usable_channels(),
 							get_payment_info,
@@ -15344,6 +15385,7 @@ where
 					InvoiceRequestVerifiedFromOffer::ExplicitKeys(request) => {
 						let result = self.flow.create_invoice_builder_from_invoice_request_without_keys(
 							&self.router,
+							&DefaultCurrencyConversion,
 							&request,
 							self.list_usable_channels(),
 							get_payment_info,
@@ -18101,6 +18143,7 @@ where
 			args.node_signer.get_receive_auth_key(),
 			secp_ctx.clone(),
 			args.message_router,
+			false,
 			args.logger.clone(),
 		)
 		.with_async_payments_offers_cache(async_receive_offer_cache);

lightning/src/ln/offers_tests.rs

@@ -51,13 +51,14 @@ use crate::blinded_path::payment::{Bolt12OfferContext, Bolt12RefundContext, Paym
 use crate::blinded_path::message::OffersContext;
 use crate::events::{ClosureReason, Event, HTLCHandlingFailureType, PaidBolt12Invoice, PaymentFailureReason, PaymentPurpose};
 use crate::ln::channelmanager::{Bolt12PaymentError, PaymentId, RecentPaymentDetails, RecipientOnionFields, Retry, self};
+use crate::offers::flow::OfferMessageFlowEvent;
 use crate::types::features::Bolt12InvoiceFeatures;
 use crate::ln::functional_test_utils::*;
 use crate::ln::msgs::{BaseMessageHandler, ChannelMessageHandler, Init, NodeAnnouncement, OnionMessage, OnionMessageHandler, RoutingMessageHandler, SocketAddress, UnsignedGossipMessage, UnsignedNodeAnnouncement};
 use crate::ln::outbound_payment::IDEMPOTENCY_TIMEOUT_TICKS;
 use crate::offers::invoice::Bolt12Invoice;
 use crate::offers::invoice_error::InvoiceError;
-use crate::offers::invoice_request::{InvoiceRequest, InvoiceRequestFields, InvoiceRequestVerifiedFromOffer};
+use crate::offers::invoice_request::{DefaultCurrencyConversion, InvoiceRequest, InvoiceRequestFields, InvoiceRequestVerifiedFromOffer};
 use crate::offers::nonce::Nonce;
 use crate::offers::parse::Bolt12SemanticError;
 use crate::onion_message::messenger::{DefaultMessageRouter, Destination, MessageSendInstructions, NodeIdMessageRouter, NullMessageRouter, PeeledOnion, PADDED_PATH_LENGTH};
@@ -866,6 +867,119 @@ fn creates_and_pays_for_offer_using_one_hop_blinded_path() {
 	expect_recent_payment!(bob, RecentPaymentDetails::Fulfilled, payment_id);
 }
 
+/// Checks that an offer can be paid through a one-hop blinded path and that ephemeral pubkeys are
+/// used rather than exposing a node's pubkey. However, the node's pubkey is still used as the
+/// introduction node of the blinded path.
+#[test]
+fn creates_and_manually_respond_to_ir_then_pays_for_offer_using_one_hop_blinded_path() {
+	let chanmon_cfgs = create_chanmon_cfgs(2);
+	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+	let mut node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+	node_chanmgrs[0].flow.enable_events();
+	let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+	create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 10_000_000, 1_000_000_000);
+
+	let alice = &nodes[0];
+	let alice_id = alice.node.get_our_node_id();
+	let bob = &nodes[1];
+	let bob_id = bob.node.get_our_node_id();
+
+	let offer = alice.node
+		.create_offer_builder().unwrap()
+		.amount_msats(10_000_000)
+		.build().unwrap();
+	assert_ne!(offer.issuer_signing_pubkey(), Some(alice_id));
+	assert!(!offer.paths().is_empty());
+	for path in offer.paths() {
+		assert!(check_compact_path_introduction_node(&path, bob, alice_id));
+	}
+
+	let payment_id = PaymentId([1; 32]);
+	bob.node.pay_for_offer(&offer, None, payment_id, Default::default()).unwrap();
+	expect_recent_payment!(bob, RecentPaymentDetails::AwaitingInvoice, payment_id);
+
+	let onion_message = bob.onion_messenger.next_onion_message_for_peer(alice_id).unwrap();
+	alice.onion_messenger.handle_onion_message(bob_id, &onion_message);
+
+	let flow_events = alice.node.flow.release_pending_flow_events();
+	assert_eq!(flow_events.len(), 1, "expected exactly one flow event");
+
+	let (invoice_request, reply_path) = match flow_events.into_iter().next().unwrap() {
+		OfferMessageFlowEvent::InvoiceRequestReceived {
+			invoice_request: InvoiceRequestVerifiedFromOffer::DerivedKeys(req),
+			reply_path
+		} => (req, reply_path),
+		_ => panic!("Unexpected flow event"),
+	};
+
+	let payment_context = PaymentContext::Bolt12Offer(Bolt12OfferContext {
+		offer_id: offer.id(),
+		invoice_request: InvoiceRequestFields {
+			payer_signing_pubkey: invoice_request.payer_signing_pubkey(),
+			quantity: None,
+			payer_note_truncated: None,
+			human_readable_name: None,
+		},
+	});
+	assert_eq!(invoice_request.amount_msats(), Some(10_000_000));
+	assert_ne!(invoice_request.payer_signing_pubkey(), bob_id);
+	assert!(check_compact_path_introduction_node(&reply_path, alice, bob_id));
+
+	// Create response for invoice request manually.
+	let get_payment_info = |amount_msats, relative_expiry| {
+		alice
+			.node
+			.create_inbound_payment(Some(amount_msats), relative_expiry, None)
+			.map_err(|_| Bolt12SemanticError::InvalidAmount)
+	};
+
+	let router = &alice.node.router;
+	let (builder, _) = alice
+		.node
+		.flow
+		.create_invoice_builder_from_invoice_request_with_keys(
+			router,
+			&DefaultCurrencyConversion {},
+			&invoice_request,
+			alice.node.list_usable_channels(),
+			get_payment_info,
+		)
+		.expect("failed to create builder with derived keys");
+
+	let invoice = builder
+		.build_and_sign(&alice.node.secp_ctx)
+		.expect("failed to build and sign invoice");
+
+	alice
+		.node
+		.flow
+		.enqueue_invoice_using_reply_paths(
+			invoice,
+			&[reply_path],
+			alice.node.get_peers_for_blinded_path(),
+		)
+		.expect("failed to enqueue invoice");
+
+	let onion_message = alice.onion_messenger.next_onion_message_for_peer(bob_id).unwrap();
+	bob.onion_messenger.handle_onion_message(alice_id, &onion_message);
+
+	let (invoice, reply_path) = extract_invoice(bob, &onion_message);
+	assert_eq!(invoice.amount_msats(), 10_000_000);
+	assert_ne!(invoice.signing_pubkey(), alice_id);
+	assert!(!invoice.payment_paths().is_empty());
+	for path in invoice.payment_paths() {
+		assert_eq!(path.introduction_node(), &IntroductionNode::NodeId(alice_id));
+	}
+	assert!(check_compact_path_introduction_node(&reply_path, bob, alice_id));
+
+	route_bolt12_payment(bob, &[alice], &invoice);
+	expect_recent_payment!(bob, RecentPaymentDetails::Pending, payment_id);
+
+	claim_bolt12_payment(bob, &[alice], payment_context, &invoice);
+	expect_recent_payment!(bob, RecentPaymentDetails::Fulfilled, payment_id);
+}
+
 /// Checks that a refund can be paid through a one-hop blinded path and that ephemeral pubkeys are
 /// used rather than exposing a node's pubkey. However, the node's pubkey is still used as the
 /// introduction node of the blinded path.
@@ -2331,7 +2445,7 @@ fn fails_paying_invoice_with_unknown_required_features() {
 
 	let invoice = match verified_invoice_request {
 		InvoiceRequestVerifiedFromOffer::DerivedKeys(request) => {
-			request.respond_using_derived_keys_no_std(payment_paths, payment_hash, created_at).unwrap()
+			request.respond_using_derived_keys_no_std(&DefaultCurrencyConversion, payment_paths, payment_hash, created_at).unwrap()
 				.features_unchecked(Bolt12InvoiceFeatures::unknown())
 				.build_and_sign(&secp_ctx).unwrap()
 		},