Trampoline payload construction method

Trampoline routing relies on serializing an inner onion within the
hop data. In this commit, we introduce the method to serialize it based
on the augmented path data introduced in the previous commit.

Author: arik-so

lightning/src/ln/blinded_payment_tests.rs

@@ -365,7 +365,7 @@ fn do_forward_checks_failure(check: ForwardCheckFail, intro_fails: bool) {
 					let onion_keys = onion_utils::construct_onion_keys(&Secp256k1::new(), &route.paths[0], &session_priv).unwrap();
 					let cur_height = nodes[0].best_block_info().1;
 					let (mut onion_payloads, ..) = onion_utils::build_onion_payloads(
-						&route.paths[0], amt_msat, &recipient_onion_fields, cur_height, &None, None).unwrap();
+						&route.paths[0], amt_msat, &recipient_onion_fields, cur_height, &None, None, None).unwrap();
 					// Remove the receive payload so the blinded forward payload is encoded as a final payload
 					// (i.e. next_hop_hmac == [0; 32])
 					onion_payloads.pop();
@@ -935,7 +935,7 @@ fn do_multi_hop_receiver_fail(check: ReceiveCheckFail) {
 			let cur_height = nodes[0].best_block_info().1;
 			let recipient_onion_fields = RecipientOnionFields::spontaneous_empty();
 			let (mut onion_payloads, ..) = onion_utils::build_onion_payloads(
-				&route.paths[0], amt_msat, &recipient_onion_fields, cur_height, &None, None).unwrap();
+				&route.paths[0], amt_msat, &recipient_onion_fields, cur_height, &None, None, None).unwrap();
 
 			let update_add = &mut payment_event_1_2.msgs[0];
 			onion_payloads.last_mut().map(|p| {

lightning/src/ln/functional_tests.rs

@@ -1428,7 +1428,7 @@ fn test_fee_spike_violation_fails_htlc() {
 	let onion_keys = onion_utils::construct_onion_keys(&secp_ctx, &route.paths[0], &session_priv).unwrap();
 	let recipient_onion_fields = RecipientOnionFields::secret_only(payment_secret);
 	let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0],
-		3460001, &recipient_onion_fields, cur_height, &None, None).unwrap();
+		3460001, &recipient_onion_fields, cur_height, &None, None, None).unwrap();
 	let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &payment_hash).unwrap();
 	let msg = msgs::UpdateAddHTLC {
 		channel_id: chan.2,
@@ -1623,7 +1623,7 @@ fn test_chan_reserve_violation_inbound_htlc_outbound_channel() {
 	let onion_keys = onion_utils::construct_onion_keys(&secp_ctx, &route.paths[0], &session_priv).unwrap();
 	let recipient_onion_fields = RecipientOnionFields::secret_only(payment_secret);
 	let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(&route.paths[0],
-		700_000, &recipient_onion_fields, cur_height, &None, None).unwrap();
+		700_000, &recipient_onion_fields, cur_height, &None, None, None).unwrap();
 	let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &payment_hash).unwrap();
 	let msg = msgs::UpdateAddHTLC {
 		channel_id: chan.2,
@@ -1803,7 +1803,7 @@ fn test_chan_reserve_violation_inbound_htlc_inbound_chan() {
 	let onion_keys = onion_utils::construct_onion_keys(&secp_ctx, &route_2.paths[0], &session_priv).unwrap();
 	let recipient_onion_fields = RecipientOnionFields::spontaneous_empty();
 	let (onion_payloads, htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(
-		&route_2.paths[0], recv_value_2, &recipient_onion_fields, cur_height, &None, None).unwrap();
+		&route_2.paths[0], recv_value_2, &recipient_onion_fields, cur_height, &None, None, None).unwrap();
 	let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &our_payment_hash_1).unwrap();
 	let msg = msgs::UpdateAddHTLC {
 		channel_id: chan.2,
@@ -3856,7 +3856,7 @@ fn fail_backward_pending_htlc_upon_channel_failure() {
 		let current_height = nodes[1].node.best_block.read().unwrap().height + 1;
 		let recipient_onion_fields = RecipientOnionFields::secret_only(payment_secret);
 		let (onion_payloads, _amount_msat, cltv_expiry) = onion_utils::build_onion_payloads(
-			&route.paths[0], 50_000, &recipient_onion_fields, current_height, &None, None).unwrap();
+			&route.paths[0], 50_000, &recipient_onion_fields, current_height, &None, None, None).unwrap();
 		let onion_keys = onion_utils::construct_onion_keys(&secp_ctx, &route.paths[0], &session_priv).unwrap();
 		let onion_routing_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &payment_hash).unwrap();
 
@@ -6852,7 +6852,7 @@ fn test_update_add_htlc_bolt2_receiver_check_max_htlc_limit() {
 	let onion_keys = onion_utils::construct_onion_keys(&Secp256k1::signing_only(), &route.paths[0], &session_priv).unwrap();
 	let recipient_onion_fields = RecipientOnionFields::secret_only(our_payment_secret);
 	let (onion_payloads, _htlc_msat, htlc_cltv) = onion_utils::build_onion_payloads(
-		&route.paths[0], send_amt, &recipient_onion_fields, cur_height, &None, None).unwrap();
+		&route.paths[0], send_amt, &recipient_onion_fields, cur_height, &None, None, None).unwrap();
 	let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &our_payment_hash).unwrap();
 
 	let mut msg = msgs::UpdateAddHTLC {
@@ -8607,7 +8607,7 @@ fn test_onion_value_mpp_set_calculation() {
 			let mut onion_keys = onion_utils::construct_onion_keys(&Secp256k1::new(), &route.paths[0], &session_priv).unwrap();
 			let recipient_onion_fields = RecipientOnionFields::secret_only(our_payment_secret);
 			let (mut onion_payloads, _, _) = onion_utils::build_onion_payloads(&route.paths[0], 100_000,
-				&recipient_onion_fields, height + 1, &None, None).unwrap();
+				&recipient_onion_fields, height + 1, &None, None, None).unwrap();
 			// Edit amt_to_forward to simulate the sender having set
 			// the final amount and the routing node taking less fee
 			if let msgs::OutboundOnionPayload::Receive {

lightning/src/ln/max_payment_path_len_tests.rs

@@ -281,7 +281,8 @@ fn blinded_path_with_custom_tlv() {
 	let reserved_packet_bytes_without_custom_tlv: usize = onion_utils::build_onion_payloads(
 		&route.paths[0], MIN_FINAL_VALUE_ESTIMATE_WITH_OVERPAY,
 		&RecipientOnionFields::spontaneous_empty(),
-		nodes[0].best_block_info().1 + DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA, &None, None
+		nodes[0].best_block_info().1 + DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA, &None,
+		None, None
 	)
 		.unwrap()
 		.0

lightning/src/ln/msgs.rs

@@ -1834,7 +1834,6 @@ mod fuzzy_internal_msgs {
 	}
 
 	pub(crate) enum OutboundTrampolinePayload<'a> {
-		#[allow(unused)]
 		Forward {
 			/// The value, in msat, of the payment after this hop's fee is deducted.
 			amt_to_forward: u64,
@@ -1854,12 +1853,10 @@ mod fuzzy_internal_msgs {
 			/// If applicable, features of the BOLT12 invoice being paid.
 			invoice_features: Option<Bolt12InvoiceFeatures>,
 		},
-		#[allow(unused)]
 		BlindedForward {
 			encrypted_tlvs: &'a Vec<u8>,
 			intro_node_blinding_point: Option<PublicKey>,
 		},
-		#[allow(unused)]
 		BlindedReceive {
 			sender_intended_htlc_amt_msat: u64,
 			total_msat: u64,

lightning/src/ln/onion_payment.rs

@@ -537,7 +537,7 @@ mod tests {
 		let path = Path { hops, blinded_tail: None, };
 		let onion_keys = super::onion_utils::construct_onion_keys(&secp_ctx, &path, &session_priv).unwrap();
 		let (onion_payloads, ..) = super::onion_utils::build_onion_payloads(
-			&path, total_amt_msat, &recipient_onion, cur_height + 1, &Some(keysend_preimage), None
+			&path, total_amt_msat, &recipient_onion, cur_height + 1, &Some(keysend_preimage), None, None
 		).unwrap();
 
 		assert!(super::onion_utils::construct_onion_packet(