Support sending custom TLVs to to blinded recipients

lightning/src/ln/blinded_payment_tests.rs

@@ -1264,3 +1264,50 @@ fn blinded_mpp_keysend() {
 		Some(payment_secret), ev.clone(), true, Some(keysend_preimage));
 	claim_payment_along_route(&nodes[0], expected_route, false, keysend_preimage);
 }
+
+#[test]
+fn custom_tlvs_to_blinded_path() {
+	let chanmon_cfgs = create_chanmon_cfgs(2);
+	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+	let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+	let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+	let chan_upd = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0).0.contents;
+
+	let amt_msat = 5000;
+	let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[1], Some(amt_msat), None);
+	let payee_tlvs = ReceiveTlvs {
+		payment_secret,
+		payment_constraints: PaymentConstraints {
+			max_cltv_expiry: u32::max_value(),
+			htlc_minimum_msat: chan_upd.htlc_minimum_msat,
+		},
+	};
+	let mut secp_ctx = Secp256k1::new();
+	let blinded_path = BlindedPath::one_hop_for_payment(
+		nodes[1].node.get_our_node_id(), payee_tlvs, TEST_FINAL_CLTV as u16,
+		&chanmon_cfgs[1].keys_manager, &secp_ctx
+	).unwrap();
+
+	let route_params = RouteParameters::from_payment_params_and_value(
+		PaymentParameters::blinded(vec![blinded_path]),
+		amt_msat,
+	);
+
+	let recipient_onion_fields = RecipientOnionFields::spontaneous_empty()
+		.with_custom_tlvs(vec![((1 << 16) + 1, vec![42, 42])])
+		.unwrap();
+	nodes[0].node.send_payment(payment_hash, recipient_onion_fields.clone(),
+		PaymentId(payment_hash.0), route_params, Retry::Attempts(0)).unwrap();
+	check_added_monitors(&nodes[0], 1);
+
+	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);
+
+	let path = &[&nodes[1]];
+	let args = PassAlongPathArgs::new(&nodes[0], path, amt_msat, payment_hash, ev)
+		.with_payment_secret(payment_secret)
+		.with_custom_tlvs(recipient_onion_fields.custom_tlvs.clone());
+	do_pass_along_path(args);
+	claim_payment(&nodes[0], &[&nodes[1]], payment_preimage);
+}

lightning/src/ln/functional_test_utils.rs

@@ -2512,6 +2512,7 @@ pub struct PassAlongPathArgs<'a, 'b, 'c, 'd> {
 	pub clear_recipient_events: bool,
 	pub expected_preimage: Option<PaymentPreimage>,
 	pub is_probe: bool,
+	pub custom_tlvs: Vec<(u64, Vec<u8>)>,
 }
 
 impl<'a, 'b, 'c, 'd> PassAlongPathArgs<'a, 'b, 'c, 'd> {
@@ -2522,7 +2523,7 @@ impl<'a, 'b, 'c, 'd> PassAlongPathArgs<'a, 'b, 'c, 'd> {
 		Self {
 			origin_node, expected_path, recv_value, payment_hash, payment_secret: None, event,
 			payment_claimable_expected: true, clear_recipient_events: true, expected_preimage: None,
-			is_probe: false,
+			is_probe: false, custom_tlvs: Vec::new(),
 		}
 	}
 	pub fn without_clearing_recipient_events(mut self) -> Self {
@@ -2546,13 +2547,17 @@ impl<'a, 'b, 'c, 'd> PassAlongPathArgs<'a, 'b, 'c, 'd> {
 		self.expected_preimage = Some(payment_preimage);
 		self
 	}
+	pub fn with_custom_tlvs(mut self, custom_tlvs: Vec<(u64, Vec<u8>)>) -> Self {
+		self.custom_tlvs = custom_tlvs;
+		self
+	}
 }
 
 pub fn do_pass_along_path<'a, 'b, 'c>(args: PassAlongPathArgs) -> Option<Event> {
 	let PassAlongPathArgs {
 		origin_node, expected_path, recv_value, payment_hash: our_payment_hash,
 		payment_secret: our_payment_secret, event: ev, payment_claimable_expected,
-		clear_recipient_events, expected_preimage, is_probe
+		clear_recipient_events, expected_preimage, is_probe, custom_tlvs
 	} = args;
 
 	let mut payment_event = SendEvent::from_event(ev);
@@ -2585,6 +2590,7 @@ pub fn do_pass_along_path<'a, 'b, 'c>(args: PassAlongPathArgs) -> Option<Event>
 						assert_eq!(our_payment_hash, *payment_hash);
 						assert_eq!(node.node.get_our_node_id(), receiver_node_id.unwrap());
 						assert!(onion_fields.is_some());
+						assert_eq!(onion_fields.as_ref().unwrap().custom_tlvs, custom_tlvs);
 						match &purpose {
 							PaymentPurpose::InvoicePayment { payment_preimage, payment_secret, .. } => {
 								assert_eq!(expected_preimage, *payment_preimage);

lightning/src/ln/msgs.rs

@@ -1701,6 +1701,7 @@ mod fuzzy_internal_msgs {
 			payment_constraints: PaymentConstraints,
 			intro_node_blinding_point: Option<PublicKey>,
 			keysend_preimage: Option<PaymentPreimage>,
+			custom_tlvs: Vec<(u64, Vec<u8>)>,
 		}
 	}
 
@@ -1737,6 +1738,7 @@ mod fuzzy_internal_msgs {
 			encrypted_tlvs: Vec<u8>,
 			intro_node_blinding_point: Option<PublicKey>, // Set if the introduction node of the blinded path is the final node
 			keysend_preimage: Option<PaymentPreimage>,
+			custom_tlvs: Vec<(u64, Vec<u8>)>,
 		}
 	}
 
@@ -2581,16 +2583,21 @@ impl Writeable for OutboundOnionPayload {
 			},
 			Self::BlindedReceive {
 				sender_intended_htlc_amt_msat, total_msat, cltv_expiry_height, encrypted_tlvs,
-				intro_node_blinding_point, keysend_preimage,
+				intro_node_blinding_point, keysend_preimage, ref custom_tlvs,
 			} => {
+				// We need to update [`ln::outbound_payment::RecipientOnionFields::with_custom_tlvs`]
+				// to reject any reserved types in the experimental range if new ones are ever
+				// standardized.
+				let keysend_tlv = keysend_preimage.map(|preimage| (5482373484, preimage.encode()));
+				let mut custom_tlvs: Vec<&(u64, Vec<u8>)> = custom_tlvs.iter().chain(keysend_tlv.iter()).collect();
+				custom_tlvs.sort_unstable_by_key(|(typ, _)| *typ);
 				_encode_varint_length_prefixed_tlv!(w, {
 					(2, HighZeroBytesDroppedBigSize(*sender_intended_htlc_amt_msat), required),
 					(4, HighZeroBytesDroppedBigSize(*cltv_expiry_height), required),
 					(10, *encrypted_tlvs, required_vec),
 					(12, intro_node_blinding_point, option),
-					(18, HighZeroBytesDroppedBigSize(*total_msat), required),
-					(5482373484, keysend_preimage, option)
-				});
+					(18, HighZeroBytesDroppedBigSize(*total_msat), required)
+				}, custom_tlvs.iter());
 			},
 		}
 		Ok(())
@@ -2677,6 +2684,7 @@ impl<NS: Deref> ReadableArgs<(Option<PublicKey>, &NS)> for InboundOnionPayload w
 						payment_constraints,
 						intro_node_blinding_point,
 						keysend_preimage,
+						custom_tlvs,
 					})
 				},
 			}

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, keysend_preimage, ..
+			intro_node_blinding_point, payment_constraints, keysend_preimage, custom_tlvs
 		} => {
 			check_blinded_payment_constraints(
 				sender_intended_htlc_amt_msat, cltv_expiry, &payment_constraints
@@ -152,7 +152,7 @@ pub(super) fn create_recv_pending_htlc_info(
 					}
 				})?;
 			let payment_data = msgs::FinalOnionHopData { payment_secret, total_msat };
-			(Some(payment_data), keysend_preimage, Vec::new(),
+			(Some(payment_data), keysend_preimage, custom_tlvs,
 			 sender_intended_htlc_amt_msat, cltv_expiry_height, None,
 			 intro_node_blinding_point.is_none())
 		}

lightning/src/ln/onion_utils.rs

@@ -214,6 +214,7 @@ pub(super) fn build_onion_payloads(
 							encrypted_tlvs: blinded_hop.encrypted_payload.clone(),
 							intro_node_blinding_point: blinding_point.take(),
 							keysend_preimage: *keysend_preimage,
+							custom_tlvs: recipient_onion.custom_tlvs.clone(),
 						});
 					} else {
 						res.push(msgs::OutboundOnionPayload::BlindedForward {

lightning/src/ln/payment_tests.rs

@@ -3813,14 +3813,11 @@ fn test_retry_custom_tlvs() {
 	check_added_monitors!(nodes[0], 1);
 	let mut events = nodes[0].node.get_and_clear_pending_msg_events();
 	assert_eq!(events.len(), 1);
-	let payment_claimable = pass_along_path(&nodes[0], &[&nodes[1], &nodes[2]], 1_000_000,
-		payment_hash, Some(payment_secret), events.pop().unwrap(), true, None).unwrap();
-	match payment_claimable {
-		Event::PaymentClaimable { onion_fields, .. } => {
-			assert_eq!(&onion_fields.unwrap().custom_tlvs()[..], &custom_tlvs[..]);
-		},
-		_ => panic!("Unexpected event"),
-	};
+	let path = &[&nodes[1], &nodes[2]];
+	let args = PassAlongPathArgs::new(&nodes[0], path, 1_000_000, payment_hash, events.pop().unwrap())
+		.with_payment_secret(payment_secret)
+		.with_custom_tlvs(custom_tlvs);
+	do_pass_along_path(args);
 	claim_payment_along_route(&nodes[0], &[&[&nodes[1], &nodes[2]]], false, payment_preimage);
 }