Set htlc_maximum_msat in BlindedPayInfo on blinded path construction

Author: valentinewallace

lightning/src/blinded_path/mod.rs

@@ -87,12 +87,13 @@ impl BlindedPath {
 	//  TODO: make all payloads the same size with padding + add dummy hops
 	pub fn new_for_payment<ES: EntropySource, T: secp256k1::Signing + secp256k1::Verification>(
 		intermediate_nodes: &[(PublicKey, payment::ForwardTlvs)], payee_node_id: PublicKey,
-		payee_tlvs: payment::ReceiveTlvs, entropy_source: &ES, secp_ctx: &Secp256k1<T>
+		payee_tlvs: payment::ReceiveTlvs, htlc_maximum_msat: u64, entropy_source: &ES,
+		secp_ctx: &Secp256k1<T>
 	) -> Result<(BlindedPayInfo, Self), ()> {
 		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)?;
+		let blinded_payinfo = payment::compute_payinfo(intermediate_nodes, &payee_tlvs, htlc_maximum_msat)?;
 		Ok((blinded_payinfo, BlindedPath {
 			introduction_node_id: intermediate_nodes.first().map_or(payee_node_id, |n| n.0),
 			blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),

lightning/src/blinded_path/payment.rs

@@ -178,7 +178,7 @@ fn amt_to_forward_msat(inbound_amt_msat: u64, payment_relay: &PaymentRelay) -> O
 }
 
 pub(super) fn compute_payinfo(
-	intermediate_nodes: &[(PublicKey, ForwardTlvs)], payee_tlvs: &ReceiveTlvs
+	intermediate_nodes: &[(PublicKey, ForwardTlvs)], payee_tlvs: &ReceiveTlvs, htlc_maximum_msat: u64
 ) -> Result<BlindedPayInfo, ()> {
 	let mut curr_base_fee: u64 = 0;
 	let mut curr_prop_mil: u64 = 0;
@@ -220,12 +220,13 @@ pub(super) fn compute_payinfo(
 		payee_tlvs.payment_constraints.htlc_minimum_msat, htlc_minimum_msat
 	);
 
+	if htlc_maximum_msat < htlc_minimum_msat { return Err(()) }
 	Ok(BlindedPayInfo {
 		fee_base_msat: u32::try_from(curr_base_fee).map_err(|_| ())?,
 		fee_proportional_millionths: u32::try_from(curr_prop_mil).map_err(|_| ())?,
 		cltv_expiry_delta,
 		htlc_minimum_msat,
-		htlc_maximum_msat: 21_000_000 * 100_000_000 * 1_000, // TODO
+		htlc_maximum_msat,
 		features: BlindedHopFeatures::empty(),
 	})
 }
@@ -285,11 +286,13 @@ mod tests {
 				htlc_minimum_msat: 1,
 			},
 		};
-		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs).unwrap();
+		let htlc_maximum_msat = 100_000;
+		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat).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.htlc_minimum_msat, 900);
+		assert_eq!(blinded_payinfo.htlc_maximum_msat, htlc_maximum_msat);
 	}
 
 	#[test]
@@ -301,11 +304,12 @@ mod tests {
 				htlc_minimum_msat: 1,
 			},
 		};
-		let blinded_payinfo = super::compute_payinfo(&[], &recv_tlvs).unwrap();
+		let blinded_payinfo = super::compute_payinfo(&[], &recv_tlvs, 4242).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.htlc_minimum_msat, 1);
+		assert_eq!(blinded_payinfo.htlc_maximum_msat, 4242);
 	}
 
 	#[test]
@@ -345,7 +349,8 @@ mod tests {
 				htlc_minimum_msat: 3,
 			},
 		};
-		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs).unwrap();
+		let htlc_maximum_msat = 100_000;
+		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat).unwrap();
 		assert_eq!(blinded_payinfo.htlc_minimum_msat, 2_000);
 	}
 
@@ -387,7 +392,11 @@ mod tests {
 			},
 		};
 		let htlc_minimum_msat = 3798;
-		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs).unwrap();
+		assert!(super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_minimum_msat - 1).is_err());
+
+		let htlc_maximum_msat = htlc_minimum_msat + 1;
+		let blinded_payinfo = super::compute_payinfo(&intermediate_nodes[..], &recv_tlvs, htlc_maximum_msat).unwrap();
 		assert_eq!(blinded_payinfo.htlc_minimum_msat, htlc_minimum_msat);
+		assert_eq!(blinded_payinfo.htlc_maximum_msat, htlc_maximum_msat);
 	}
 }