Handle Trampoline receives

Handle payment receives with payment details located inside an inner
onion.

Author: arik-so

Diff for: lightning/src/ln/blinded_payment_tests.rs

@@ -40,6 +40,7 @@ use crate::util::test_utils;
 use lightning_invoice::RawBolt11Invoice;
 use types::features::Features;
 use crate::blinded_path::BlindedHop;
+use crate::routing::router::Route;
 
 pub fn blinded_payment_path(
 	payment_secret: PaymentSecret, intro_node_min_htlc: u64, intro_node_max_htlc: u64,
@@ -1957,3 +1958,219 @@ fn test_trampoline_inbound_payment_decoding() {
 		panic!();
 	};
 }
+
+fn do_test_trampoline_single_hop_receive(success: bool) {
+	const TOTAL_NODE_COUNT: usize = 3;
+	let secp_ctx = Secp256k1::new();
+
+	let chanmon_cfgs = create_chanmon_cfgs(TOTAL_NODE_COUNT);
+	let node_cfgs = create_node_cfgs(TOTAL_NODE_COUNT, &chanmon_cfgs);
+	let node_chanmgrs = create_node_chanmgrs(TOTAL_NODE_COUNT, &node_cfgs, &vec![None; TOTAL_NODE_COUNT]);
+	let mut nodes = create_network(TOTAL_NODE_COUNT, &node_cfgs, &node_chanmgrs);
+
+	let (_, _, chan_id_alice_bob, _) = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0);
+	let (_, _, chan_id_bob_carol, _) = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 0);
+
+	for i in 0..TOTAL_NODE_COUNT { // connect all nodes' blocks
+		connect_blocks(&nodes[i], (TOTAL_NODE_COUNT as u32) * CHAN_CONFIRM_DEPTH + 1 - nodes[i].best_block_info().1);
+	}
+
+	let alice_node_id = nodes[0].node().get_our_node_id();
+	let bob_node_id = nodes[1].node().get_our_node_id();
+	let carol_node_id = nodes[2].node().get_our_node_id();
+
+	let alice_bob_scid = nodes[0].node().list_channels().iter().find(|c| c.channel_id == chan_id_alice_bob).unwrap().short_channel_id.unwrap();
+	let bob_carol_scid = nodes[1].node().list_channels().iter().find(|c| c.channel_id == chan_id_bob_carol).unwrap().short_channel_id.unwrap();
+
+	let amt_msat = 1000;
+	let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[2], Some(amt_msat), None);
+
+	let carol_alice_trampoline_session_priv = secret_from_hex("a0f4b8d7b6c2d0ffdfaf718f76e9decaef4d9fb38a8c4addb95c4007cc3eee03");
+	let carol_blinding_point = PublicKey::from_secret_key(&secp_ctx, &carol_alice_trampoline_session_priv);
+	let carol_blinded_hops = if success {
+		let payee_tlvs = UnauthenticatedReceiveTlvs {
+			payment_secret,
+			payment_constraints: PaymentConstraints {
+				max_cltv_expiry: u32::max_value(),
+				htlc_minimum_msat: amt_msat,
+			},
+			payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
+		};
+
+		let nonce = Nonce([42u8; 16]);
+		let expanded_key = nodes[2].keys_manager.get_inbound_payment_key();
+		let payee_tlvs = payee_tlvs.authenticate(nonce, &expanded_key);
+		let carol_unblinded_tlvs = payee_tlvs.encode();
+
+		let path = [(carol_node_id, WithoutLength(&carol_unblinded_tlvs))];
+		blinded_path::utils::construct_blinded_hops(
+			&secp_ctx, path.into_iter(), &carol_alice_trampoline_session_priv
+		).unwrap()
+	} else {
+		let payee_tlvs = blinded_path::payment::TrampolineForwardTlvs {
+			next_trampoline: alice_node_id,
+			payment_constraints: PaymentConstraints {
+				max_cltv_expiry: u32::max_value(),
+				htlc_minimum_msat: amt_msat,
+			},
+			features: BlindedHopFeatures::empty(),
+			payment_relay: PaymentRelay {
+				cltv_expiry_delta: 0,
+				fee_proportional_millionths: 0,
+				fee_base_msat: 0,
+			},
+			next_blinding_override: None,
+		};
+
+		let carol_unblinded_tlvs = payee_tlvs.encode();
+		let path = [(carol_node_id, WithoutLength(&carol_unblinded_tlvs))];
+		blinded_path::utils::construct_blinded_hops(
+			&secp_ctx, path.into_iter(), &carol_alice_trampoline_session_priv
+		).unwrap()
+	};
+
+	let route = Route {
+		paths: vec![Path {
+			hops: vec![
+				// Bob
+				RouteHop {
+					pubkey: bob_node_id,
+					node_features: NodeFeatures::empty(),
+					short_channel_id: alice_bob_scid,
+					channel_features: ChannelFeatures::empty(),
+					fee_msat: 1000,
+					cltv_expiry_delta: 48,
+					maybe_announced_channel: false,
+				},
+
+				// Carol
+				RouteHop {
+					pubkey: carol_node_id,
+					node_features: NodeFeatures::empty(),
+					short_channel_id: bob_carol_scid,
+					channel_features: ChannelFeatures::empty(),
+					fee_msat: 0,
+					cltv_expiry_delta: 48,
+					maybe_announced_channel: false,
+				}
+			],
+			blinded_tail: Some(BlindedTail {
+				trampoline_hops: vec![
+					// Carol
+					TrampolineHop {
+						pubkey: carol_node_id,
+						node_features: Features::empty(),
+						fee_msat: amt_msat,
+						cltv_expiry_delta: 24,
+					},
+				],
+				hops: carol_blinded_hops,
+				blinding_point: carol_blinding_point,
+				excess_final_cltv_expiry_delta: 39,
+				final_value_msat: amt_msat,
+			})
+		}],
+		route_params: None,
+	};
+
+	nodes[0].node.send_payment_with_route(route.clone(), payment_hash, RecipientOnionFields::spontaneous_empty(), PaymentId(payment_hash.0)).unwrap();
+
+	check_added_monitors!(&nodes[0], 1);
+
+	if success {
+		pass_along_route(&nodes[0], &[&[&nodes[1], &nodes[2]]], amt_msat, payment_hash, payment_secret);
+		claim_payment(&nodes[0], &[&nodes[1], &nodes[2]], payment_preimage);
+	} else {
+		let replacement_onion = {
+			// create a substitute onion where the last Trampoline hop is a forward
+			let trampoline_secret_key = secret_from_hex("0134928f7b7ca6769080d70f16be84c812c741f545b49a34db47ce338a205799");
+			let prng_seed = secret_from_hex("fe02b4b9054302a3ddf4e1e9f7c411d644aebbd295218ab009dca94435f775a9");
+			let recipient_onion_fields = RecipientOnionFields::spontaneous_empty();
+
+			let mut blinded_tail = route.paths[0].blinded_tail.clone().unwrap();
+
+			// append some dummy blinded hop so the intro hop looks like a forward
+			blinded_tail.hops.push(BlindedHop {
+				blinded_node_id: alice_node_id,
+				encrypted_payload: vec![],
+			});
+
+			let (mut trampoline_payloads, outer_total_msat, outer_starting_htlc_offset) = onion_utils::build_trampoline_onion_payloads(&blinded_tail, amt_msat, &recipient_onion_fields, 32, &None).unwrap();
+
+			// pop the last dummy hop
+			trampoline_payloads.pop();
+
+			let trampoline_onion_keys = onion_utils::construct_trampoline_onion_keys(&secp_ctx, &route.paths[0].blinded_tail.as_ref().unwrap(), &trampoline_secret_key).unwrap();
+			let trampoline_packet = onion_utils::construct_trampoline_onion_packet(
+				trampoline_payloads,
+				trampoline_onion_keys,
+				prng_seed.secret_bytes(),
+				&payment_hash,
+				None,
+			).unwrap();
+
+			let outer_session_priv = secret_from_hex("e52c20461ed7acd46c4e7b591a37610519179482887bd73bf3b94617f8f03677");
+
+			let (outer_payloads, _, _) = onion_utils::build_onion_payloads(&route.paths[0], outer_total_msat, &recipient_onion_fields, outer_starting_htlc_offset, &None, None, Some(trampoline_packet)).unwrap();
+			let outer_onion_keys = onion_utils::construct_onion_keys(&secp_ctx, &route.clone().paths[0], &outer_session_priv).unwrap();
+			let outer_packet = onion_utils::construct_onion_packet(
+				outer_payloads,
+				outer_onion_keys,
+				prng_seed.secret_bytes(),
+				&payment_hash,
+			).unwrap();
+
+			outer_packet
+		};
+
+		let mut events = nodes[0].node.get_and_clear_pending_msg_events();
+		assert_eq!(events.len(), 1);
+		let mut first_message_event = remove_first_msg_event_to_node(&nodes[1].node.get_our_node_id(), &mut events);
+		let mut update_message = match first_message_event {
+			MessageSendEvent::UpdateHTLCs { ref mut updates, .. } => {
+				assert_eq!(updates.update_add_htlcs.len(), 1);
+				updates.update_add_htlcs.get_mut(0)
+			},
+			_ => panic!()
+		};
+		update_message.map(|msg| {
+			msg.onion_routing_packet = replacement_onion.clone();
+		});
+
+		let route: &[&Node] = &[&nodes[1], &nodes[2]];
+		let args = PassAlongPathArgs::new(&nodes[0], route, amt_msat, payment_hash, first_message_event)
+			.with_payment_preimage(payment_preimage)
+			.without_claimable_event()
+			.expect_failure(HTLCDestination::InvalidOnion);
+		do_pass_along_path(args);
+
+		{
+			let unblinded_node_updates = get_htlc_update_msgs!(nodes[2], nodes[1].node.get_our_node_id());
+			nodes[1].node.handle_update_fail_htlc(
+				nodes[2].node.get_our_node_id(), &unblinded_node_updates.update_fail_htlcs[0]
+			);
+			do_commitment_signed_dance(&nodes[1], &nodes[2], &unblinded_node_updates.commitment_signed, true, false);
+		}
+		{
+			let unblinded_node_updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
+			nodes[0].node.handle_update_fail_htlc(
+				nodes[1].node.get_our_node_id(), &unblinded_node_updates.update_fail_htlcs[0]
+			);
+			do_commitment_signed_dance(&nodes[0], &nodes[1], &unblinded_node_updates.commitment_signed, false, false);
+		}
+		{
+			let payment_failed_conditions = PaymentFailedConditions::new()
+				.expected_htlc_error_data(INVALID_ONION_BLINDING, &[0; 0]);
+			expect_payment_failed_conditions(&nodes[0], payment_hash, true, payment_failed_conditions);
+		}
+	}
+}
+
+#[test]
+fn test_trampoline_single_hop_receive() {
+	// Simulate a payment of A (0) -> B (1) -> C(Trampoline (blinded intro)) (2)
+	do_test_trampoline_single_hop_receive(true);
+
+	// Simulate a payment failure of A (0) -> B (1) -> C(Trampoline (blinded forward)) (2)
+	do_test_trampoline_single_hop_receive(false);
+}

Diff for: lightning/src/ln/onion_payment.rs

@@ -265,7 +265,36 @@ pub(super) fn create_recv_pending_htlc_info(
 			 sender_intended_htlc_amt_msat, cltv_expiry_height, None, Some(payment_context),
 			 intro_node_blinding_point.is_none(), true, invoice_request)
 		}
-		onion_utils::Hop::TrampolineReceive { .. } | onion_utils::Hop::TrampolineBlindedReceive { .. } => todo!(),
+		onion_utils::Hop::TrampolineReceive {
+			trampoline_hop_data: msgs::InboundOnionReceivePayload {
+				payment_data, keysend_preimage, custom_tlvs, sender_intended_htlc_amt_msat,
+				cltv_expiry_height, payment_metadata, ..
+			}, ..
+		} =>
+			(payment_data, keysend_preimage, custom_tlvs, sender_intended_htlc_amt_msat,
+				cltv_expiry_height, payment_metadata, None, false, keysend_preimage.is_none(), None),
+		onion_utils::Hop::TrampolineBlindedReceive {
+			trampoline_hop_data: msgs::InboundOnionBlindedReceivePayload {
+				sender_intended_htlc_amt_msat, total_msat, cltv_expiry_height, payment_secret,
+				intro_node_blinding_point, payment_constraints, payment_context, keysend_preimage,
+				custom_tlvs, invoice_request
+			}, ..
+		} => {
+			check_blinded_payment_constraints(
+				sender_intended_htlc_amt_msat, cltv_expiry, &payment_constraints,
+			)
+				.map_err(|()| {
+					InboundHTLCErr {
+						err_code: INVALID_ONION_BLINDING,
+						err_data: vec![0; 32],
+						msg: "Amount or cltv_expiry violated blinded payment constraints within Trampoline onion",
+					}
+				})?;
+			let payment_data = msgs::FinalOnionHopData { payment_secret, total_msat };
+			(Some(payment_data), keysend_preimage, custom_tlvs,
+				sender_intended_htlc_amt_msat, cltv_expiry_height, None, Some(payment_context),
+				intro_node_blinding_point.is_none(), true, invoice_request)
+		},
 		onion_utils::Hop::Forward { .. } => {
 			return Err(InboundHTLCErr {
 				err_code: 0x4000|22,