Support receiving keysend payments to blinded paths.

lightning/src/ln/blinded_payment_tests.rs

@@ -1183,3 +1183,84 @@ fn conditionally_round_fwd_amt() {
 	let expected_fee = pass_claimed_payment_along_route(args);
 	expect_payment_sent(&nodes[0], payment_preimage, Some(Some(expected_fee)), true, true);
 }
+
+#[test]
+fn blinded_keysend() {
+	let mut mpp_keysend_config = test_default_channel_config();
+	mpp_keysend_config.accept_mpp_keysend = true;
+	let chanmon_cfgs = create_chanmon_cfgs(3);
+	let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
+	let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, Some(mpp_keysend_config)]);
+	let mut nodes = create_network(3, &node_cfgs, &node_chanmgrs);
+	create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0);
+	let chan_upd_1_2 = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 0).0.contents;
+
+	let amt_msat = 5000;
+	let (keysend_preimage, _, payment_secret) = get_payment_preimage_hash(&nodes[2], None, None);
+	let route_params = get_blinded_route_parameters(amt_msat, payment_secret, 1,
+		1_0000_0000,
+		nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(),
+		&[&chan_upd_1_2], &chanmon_cfgs[2].keys_manager);
+
+	let payment_hash = nodes[0].node.send_spontaneous_payment_with_retry(Some(keysend_preimage), RecipientOnionFields::spontaneous_empty(), PaymentId(keysend_preimage.0), route_params, Retry::Attempts(0)).unwrap();
+	check_added_monitors(&nodes[0], 1);
+
+	let expected_route: &[&[&Node]] = &[&[&nodes[1], &nodes[2]]];
+	let mut events = nodes[0].node.get_and_clear_pending_msg_events();
+	assert_eq!(events.len(), 1);
+
+	let ev = remove_first_msg_event_to_node(&nodes[1].node.get_our_node_id(), &mut events);
+	pass_along_path(&nodes[0], expected_route[0], amt_msat, payment_hash, Some(payment_secret), ev.clone(), true, Some(keysend_preimage));
+	claim_payment_along_route(&nodes[0], expected_route, false, keysend_preimage);
+}
+
+#[test]
+fn blinded_mpp_keysend() {
+	let mut mpp_keysend_config = test_default_channel_config();
+	mpp_keysend_config.accept_mpp_keysend = true;
+	let chanmon_cfgs = create_chanmon_cfgs(4);
+	let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
+	let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, Some(mpp_keysend_config)]);
+	let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
+
+	create_announced_chan_between_nodes(&nodes, 0, 1);
+	create_announced_chan_between_nodes(&nodes, 0, 2);
+	let chan_1_3 = create_announced_chan_between_nodes(&nodes, 1, 3);
+	let chan_2_3 = create_announced_chan_between_nodes(&nodes, 2, 3);
+
+	let amt_msat = 15_000_000;
+	let (keysend_preimage, _, payment_secret) = get_payment_preimage_hash(&nodes[3], None, None);
+	let route_params = {
+		let pay_params = PaymentParameters::blinded(
+			vec![
+				blinded_payment_path(payment_secret, 1, 1_0000_0000,
+					vec![nodes[1].node.get_our_node_id(), nodes[3].node.get_our_node_id()], &[&chan_1_3.0.contents],
+					&chanmon_cfgs[3].keys_manager
+				),
+				blinded_payment_path(payment_secret, 1, 1_0000_0000,
+					vec![nodes[2].node.get_our_node_id(), nodes[3].node.get_our_node_id()], &[&chan_2_3.0.contents],
+					&chanmon_cfgs[3].keys_manager
+				),
+			]
+		)
+			.with_bolt12_features(channelmanager::provided_bolt12_invoice_features(&UserConfig::default()))
+			.unwrap();
+		RouteParameters::from_payment_params_and_value(pay_params, amt_msat)
+	};
+
+	let payment_hash = nodes[0].node.send_spontaneous_payment_with_retry(Some(keysend_preimage), RecipientOnionFields::spontaneous_empty(), PaymentId(keysend_preimage.0), route_params, Retry::Attempts(0)).unwrap();
+	check_added_monitors!(nodes[0], 2);
+
+	let expected_route: &[&[&Node]] = &[&[&nodes[1], &nodes[3]], &[&nodes[2], &nodes[3]]];
+	let mut events = nodes[0].node.get_and_clear_pending_msg_events();
+	assert_eq!(events.len(), 2);
+
+	let ev = remove_first_msg_event_to_node(&nodes[1].node.get_our_node_id(), &mut events);
+	pass_along_path(&nodes[0], expected_route[0], amt_msat, payment_hash.clone(),
+		Some(payment_secret), ev.clone(), false, Some(keysend_preimage));
+
+	let ev = remove_first_msg_event_to_node(&nodes[2].node.get_our_node_id(), &mut events);
+	pass_along_path(&nodes[0], expected_route[1], amt_msat, payment_hash.clone(),
+		Some(payment_secret), ev.clone(), true, Some(keysend_preimage));
+	claim_payment_along_route(&nodes[0], expected_route, false, keysend_preimage);
+}

lightning/src/ln/channelmanager.rs

@@ -200,6 +200,8 @@ pub enum PendingHTLCRouting {
 		/// For HTLCs received by LDK, these will ultimately bubble back up as
 		/// [`RecipientOnionFields::custom_tlvs`].
 		custom_tlvs: Vec<(u64, Vec<u8>)>,
+		/// Set if this HTLC is the final hop in a multi-hop blinded path.
+		requires_blinded_error: bool,
 	},
 }
 
@@ -221,6 +223,7 @@ impl PendingHTLCRouting {
 		match self {
 			Self::Forward { blinded: Some(BlindedForward { failure, .. }), .. } => Some(*failure),
 			Self::Receive { requires_blinded_error: true, .. } => Some(BlindedFailure::FromBlindedNode),
+			Self::ReceiveKeysend { requires_blinded_error: true, .. } => Some(BlindedFailure::FromBlindedNode),
 			_ => None,
 		}
 	}
@@ -4523,7 +4526,10 @@ where
 										(incoming_cltv_expiry, OnionPayload::Invoice { _legacy_hop_data },
 											Some(payment_data), phantom_shared_secret, onion_fields)
 									},
-									PendingHTLCRouting::ReceiveKeysend { payment_data, payment_preimage, payment_metadata, incoming_cltv_expiry, custom_tlvs } => {
+									PendingHTLCRouting::ReceiveKeysend {
+										payment_data, payment_preimage, payment_metadata,
+										incoming_cltv_expiry, custom_tlvs, requires_blinded_error: _
+									} => {
 										let onion_fields = RecipientOnionFields {
 											payment_secret: payment_data.as_ref().map(|data| data.payment_secret),
 											payment_metadata,
@@ -9766,6 +9772,7 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
 	},
 	(2, ReceiveKeysend) => {
 		(0, payment_preimage, required),
+		(1, requires_blinded_error, (default_value, false)),
 		(2, incoming_cltv_expiry, required),
 		(3, payment_metadata, option),
 		(4, payment_data, option), // Added in 0.0.116

lightning/src/ln/onion_payment.rs

@@ -139,7 +139,7 @@ pub(super) fn create_recv_pending_htlc_info(
 			 cltv_expiry_height, payment_metadata, false),
 		msgs::InboundOnionPayload::BlindedReceive {
 			sender_intended_htlc_amt_msat, total_msat, cltv_expiry_height, payment_secret,
-			intro_node_blinding_point, payment_constraints, ..
+			intro_node_blinding_point, payment_constraints, keysend_preimage, ..
 		} => {
 			check_blinded_payment_constraints(
 				sender_intended_htlc_amt_msat, cltv_expiry, &payment_constraints
@@ -152,8 +152,9 @@ pub(super) fn create_recv_pending_htlc_info(
 					}
 				})?;
 			let payment_data = msgs::FinalOnionHopData { payment_secret, total_msat };
-			(Some(payment_data), None, Vec::new(), sender_intended_htlc_amt_msat, cltv_expiry_height,
+			(Some(payment_data), keysend_preimage, Vec::new(),
-			 None, intro_node_blinding_point.is_none())
+			 sender_intended_htlc_amt_msat, cltv_expiry_height, None,
+			 intro_node_blinding_point.is_none())
 		}
 		msgs::InboundOnionPayload::Forward { .. } => {
 			return Err(InboundHTLCErr {
@@ -232,6 +233,7 @@ pub(super) fn create_recv_pending_htlc_info(
 			payment_metadata,
 			incoming_cltv_expiry: onion_cltv_expiry,
 			custom_tlvs,
+			requires_blinded_error,
 		}
 	} else if let Some(data) = payment_data {
 		PendingHTLCRouting::Receive {