Set htlc_maximum_msat in BlindedPayInfo on route construction

lightning/src/blinded_path/mod.rs

@@ -89,7 +89,8 @@ impl BlindedPath {
 	/// * any unknown features are required in the provided [`BlindedPaymentTlvs`]
 	//  TODO: make all payloads the same size with padding + add dummy hops
 	pub fn new_for_payment<ES: EntropySource, T: secp256k1::Signing + secp256k1::Verification>(
-		path: &[(PublicKey, BlindedPaymentTlvs)], entropy_source: &ES, secp_ctx: &Secp256k1<T>
+		path: &[(PublicKey, BlindedPaymentTlvs)], htlc_maximum_msat: u64, entropy_source: &ES,
+		secp_ctx: &Secp256k1<T>
 	) -> Result<(BlindedPayInfo, Self), ()> {
 		if path.len() < 1 { return Err(()) }
 		let mut found_recv_payload = false;
@@ -104,7 +105,7 @@ 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(path)?;
+		let blinded_payinfo = payment::compute_payinfo(path, htlc_maximum_msat)?;
 		Ok((blinded_payinfo, BlindedPath {
 			introduction_node_id: path[0].0,
 			blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),

lightning/src/blinded_path/payment.rs

@@ -168,7 +168,7 @@ pub(super) fn blinded_hops<T: secp256k1::Signing + secp256k1::Verification>(
 }
 
 pub(super) fn compute_payinfo(
-	path: &[(PublicKey, BlindedPaymentTlvs)]
+	path: &[(PublicKey, BlindedPaymentTlvs)], htlc_maximum_msat: u64,
 ) -> Result<BlindedPayInfo, ()> {
 	let mut curr_base_fee: u32 = 0;
 	let mut curr_prop_mil: u32 = 0;
@@ -195,14 +195,15 @@ pub(super) fn compute_payinfo(
 			.map(|f| f / 1_000_000)
 			.ok_or(())?;
 	}
+	let htlc_minimum_msat = path.iter().map(|(_, tlvs)| tlvs.htlc_minimum_msat()).max().unwrap_or(0);
+	if htlc_maximum_msat < htlc_minimum_msat { return Err(()) }
 	Ok(BlindedPayInfo {
 		fee_base_msat: curr_base_fee,
 		fee_proportional_millionths: curr_prop_mil,
 		cltv_expiry_delta: path.iter().map(|(_, tlvs)| tlvs.cltv_expiry_delta())
 			.try_fold(0u16, |acc, delta| acc.checked_add(delta)).ok_or(())?,
-		htlc_minimum_msat: path.iter().map(|(_, tlvs)| tlvs.htlc_minimum_msat()).max().unwrap_or(0),
-		// TODO: this field isn't present in route blinding encrypted data
-		htlc_maximum_msat: 21_000_000 * 100_000_000 * 1_000, // Total bitcoin supply
+		htlc_minimum_msat,
+		htlc_maximum_msat,
 		features: BlindedHopFeatures::empty(),
 	})
 }
@@ -264,11 +265,12 @@ mod tests {
 				htlc_minimum_msat: 1,
 			},
 		})];
-		let blinded_payinfo = super::compute_payinfo(&path[..]).unwrap();
+		let blinded_payinfo = super::compute_payinfo(&path[..], 4242).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, 1_000);
+		assert_eq!(blinded_payinfo.htlc_maximum_msat, 4242);
 	}
 
 	#[test]
@@ -281,7 +283,7 @@ mod tests {
 				htlc_minimum_msat: 1,
 			},
 		})];
-		let blinded_payinfo = super::compute_payinfo(&path[..]).unwrap();
+		let blinded_payinfo = super::compute_payinfo(&path[..], 42).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);
@@ -313,7 +315,7 @@ mod tests {
 			},
 			features: BlindedHopFeatures::empty(),
 		})];
-		assert!(BlindedPath::new_for_payment(&out_of_order_payloads_path[..], &keys_manager, &secp_ctx).is_err());
+		assert!(BlindedPath::new_for_payment(&out_of_order_payloads_path[..], 1_000_000, &keys_manager, &secp_ctx).is_err());
 
 		let multiple_recv_payloads_path = vec![(dummy_pk, BlindedPaymentTlvs::Receive {
 			payment_secret: PaymentSecret([0; 32]),
@@ -328,7 +330,7 @@ mod tests {
 				htlc_minimum_msat: 1,
 			},
 		})];
-		assert!(BlindedPath::new_for_payment(&multiple_recv_payloads_path[..], &keys_manager, &secp_ctx).is_err());
+		assert!(BlindedPath::new_for_payment(&multiple_recv_payloads_path[..], 1_000_000, &keys_manager, &secp_ctx).is_err());
 
 		let missing_recv_payload_path = vec![(dummy_pk, BlindedPaymentTlvs::Forward {
 			short_channel_id: 0,
@@ -343,6 +345,6 @@ mod tests {
 			},
 			features: BlindedHopFeatures::empty(),
 		})];
-		assert!(BlindedPath::new_for_payment(&missing_recv_payload_path[..], &keys_manager, &secp_ctx).is_err());
+		assert!(BlindedPath::new_for_payment(&missing_recv_payload_path[..], 1_000_000, &keys_manager, &secp_ctx).is_err());
 	}
 }