Add min_final_cltv_delta to aggregated CLTV delta.

The spec is currently missing this requirement so we were also, though it seems
somewhat obvious in retrospect.

lightning/src/blinded_path/mod.rs

@@ -114,7 +114,9 @@ impl BlindedPath {
 		let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 		let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
 
-		let blinded_payinfo = payment::compute_payinfo(intermediate_nodes, &payee_tlvs, htlc_maximum_msat)?;
+		let blinded_payinfo = payment::compute_payinfo(
+			intermediate_nodes, &payee_tlvs, htlc_maximum_msat, min_final_cltv_expiry_delta
+		)?;
 		Ok((blinded_payinfo, BlindedPath {
 			introduction_node_id: intermediate_nodes.first().map_or(payee_node_id, |n| n.node_id),
 			blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),

lightning/src/blinded_path/payment.rs

@@ -215,11 +215,12 @@ pub(crate) fn amt_to_forward_msat(inbound_amt_msat: u64, payment_relay: &Payment
 }
 
 pub(super) fn compute_payinfo(
-	intermediate_nodes: &[ForwardNode], payee_tlvs: &ReceiveTlvs, payee_htlc_maximum_msat: u64
+	intermediate_nodes: &[ForwardNode], payee_tlvs: &ReceiveTlvs, payee_htlc_maximum_msat: u64,
+	min_final_cltv_expiry_delta: u16
 ) -> Result<BlindedPayInfo, ()> {
 	let mut curr_base_fee: u64 = 0;
 	let mut curr_prop_mil: u64 = 0;
-	let mut cltv_expiry_delta: u16 = 0;
+	let mut cltv_expiry_delta: u16 = min_final_cltv_expiry_delta;
 	for tlvs in intermediate_nodes.iter().rev().map(|n| &n.tlvs) {
 		// In the future, we'll want to take the intersection of all supported features for the
 		// `BlindedPayInfo`, but there are no features in that context right now.
@@ -292,6 +293,7 @@ mod tests {
 	use crate::blinded_path::payment::{ForwardNode, ForwardTlvs, ReceiveTlvs, PaymentConstraints, PaymentRelay};
 	use crate::ln::PaymentSecret;
 	use crate::ln::features::BlindedHopFeatures;
+	use crate::ln::functional_test_utils::TEST_FINAL_CLTV;
 
 	#[test]
 	fn compute_payinfo() {
@@ -339,10 +341,10 @@ mod tests {
 			},
 		};
 		let htlc_maximum_msat = 100_000;
-		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat).unwrap();
+		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat, TEST_FINAL_CLTV as u16).unwrap();
 		assert_eq!(blinded_payinfo.fee_base_msat, 201);
 		assert_eq!(blinded_payinfo.fee_proportional_millionths, 1001);
-		assert_eq!(blinded_payinfo.cltv_expiry_delta, 288);
+		assert_eq!(blinded_payinfo.cltv_expiry_delta, 288 + TEST_FINAL_CLTV as u16);
 		assert_eq!(blinded_payinfo.htlc_minimum_msat, 900);
 		assert_eq!(blinded_payinfo.htlc_maximum_msat, htlc_maximum_msat);
 	}
@@ -356,10 +358,10 @@ mod tests {
 				htlc_minimum_msat: 1,
 			},
 		};
-		let blinded_payinfo = super::compute_payinfo(&[], &recv_tlvs, 4242).unwrap();
+		let blinded_payinfo = super::compute_payinfo(&[], &recv_tlvs, 4242, TEST_FINAL_CLTV as u16).unwrap();
 		assert_eq!(blinded_payinfo.fee_base_msat, 0);
 		assert_eq!(blinded_payinfo.fee_proportional_millionths, 0);
-		assert_eq!(blinded_payinfo.cltv_expiry_delta, 0);
+		assert_eq!(blinded_payinfo.cltv_expiry_delta, TEST_FINAL_CLTV as u16);
 		assert_eq!(blinded_payinfo.htlc_minimum_msat, 1);
 		assert_eq!(blinded_payinfo.htlc_maximum_msat, 4242);
 	}
@@ -410,7 +412,7 @@ mod tests {
 			},
 		};
 		let htlc_maximum_msat = 100_000;
-		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat).unwrap();
+		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat, TEST_FINAL_CLTV as u16).unwrap();
 		assert_eq!(blinded_payinfo.htlc_minimum_msat, 2_000);
 	}
 
@@ -460,10 +462,10 @@ mod tests {
 			},
 		};
 		let htlc_minimum_msat = 3798;
-		assert!(super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_minimum_msat - 1).is_err());
+		assert!(super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_minimum_msat - 1, TEST_FINAL_CLTV as u16).is_err());
 
 		let htlc_maximum_msat = htlc_minimum_msat + 1;
-		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat).unwrap();
+		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat, TEST_FINAL_CLTV as u16).unwrap();
 		assert_eq!(blinded_payinfo.htlc_minimum_msat, htlc_minimum_msat);
 		assert_eq!(blinded_payinfo.htlc_maximum_msat, htlc_maximum_msat);
 	}
@@ -514,7 +516,7 @@ mod tests {
 			},
 		};
 
-		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, 10_000).unwrap();
+		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, 10_000, TEST_FINAL_CLTV as u16).unwrap();
 		assert_eq!(blinded_payinfo.htlc_maximum_msat, 3997);
 	}
 }

lightning/src/ln/blinded_payment_tests.rs

@@ -691,7 +691,7 @@ fn do_multi_hop_receiver_fail(check: ReceiveCheckFail) {
 			commitment_signed_dance!(nodes[2], nodes[1], (), false, true, false, false);
 		},
 		ReceiveCheckFail::ProcessPendingHTLCsCheck => {
-			assert_eq!(payment_event_1_2.msgs[0].cltv_expiry, nodes[0].best_block_info().1 + 1 + excess_final_cltv_delta_opt.unwrap() as u32);
+			assert_eq!(payment_event_1_2.msgs[0].cltv_expiry, nodes[0].best_block_info().1 + 1 + excess_final_cltv_delta_opt.unwrap() as u32 + TEST_FINAL_CLTV);
 			nodes[2].node.handle_update_add_htlc(&nodes[1].node.get_our_node_id(), &payment_event_1_2.msgs[0]);
 			check_added_monitors!(nodes[2], 0);
 			do_commitment_signed_dance(&nodes[2], &nodes[1], &payment_event_1_2.commitment_msg, true, true);