Fuzz test blinded payment pathfinding

fuzz/src/router.rs

@@ -11,9 +11,12 @@ use bitcoin::blockdata::script::Builder;
 use bitcoin::blockdata::transaction::TxOut;
 use bitcoin::hash_types::BlockHash;
 
+use lightning::blinded_path::{BlindedHop, BlindedPath};
 use lightning::chain::transaction::OutPoint;
 use lightning::ln::channelmanager::{self, ChannelDetails, ChannelCounterparty};
+use lightning::ln::features::{BlindedHopFeatures, Bolt12InvoiceFeatures};
 use lightning::ln::msgs;
+use lightning::offers::invoice::BlindedPayInfo;
 use lightning::routing::gossip::{NetworkGraph, RoutingFees};
 use lightning::routing::utxo::{UtxoFuture, UtxoLookup, UtxoLookupError, UtxoResult};
 use lightning::routing::router::{find_route, PaymentParameters, RouteHint, RouteHintHop, RouteParameters};
@@ -279,7 +282,7 @@ pub fn do_test<Out: test_logger::Output>(data: &[u8], out: Out) {
 				net_graph.channel_failed_permanent(short_channel_id);
 			},
 			_ if node_pks.is_empty() => {},
-			_ => {
+			x if x < 250 => {
 				let mut first_hops_vec = Vec::new();
 				let first_hops = first_hops!(first_hops_vec);
 				let mut last_hops = Vec::new();
@@ -316,6 +319,57 @@ pub fn do_test<Out: test_logger::Output>(data: &[u8], out: Out) {
 						&logger, &scorer, &ProbabilisticScoringFeeParameters::default(), &random_seed_bytes);
 				}
 			},
+			x => {
+				let mut first_hops_vec = Vec::new();
+				let first_hops = first_hops!(first_hops_vec);
+				let mut last_hops = Vec::new();
+				{
+					let count = get_slice!(1)[0];
+					for _ in 0..count {
+						// Fetch values in the same order as above to improve coverage.
+						let intro_node_id = node_pks.iter().skip(slice_to_be16(get_slice!(2)) as usize % node_pks.len()).next().unwrap();
+						let fee_base_msat = slice_to_be32(get_slice!(4));
+						let fee_proportional_millionths = slice_to_be32(get_slice!(4));
+						let cltv_expiry_delta = slice_to_be16(get_slice!(2));
+						let htlc_minimum_msat = slice_to_be64(get_slice!(8));
+						let payinfo = BlindedPayInfo {
+							fee_base_msat,
+							fee_proportional_millionths,
+							htlc_minimum_msat,
+							htlc_maximum_msat: htlc_minimum_msat.saturating_mul(100),
+							cltv_expiry_delta,
+							features: BlindedHopFeatures::empty(),
+						};
+						let num_blinded_hops = x % 250;
+						let mut blinded_hops = Vec::new();
+						for _ in 0..num_blinded_hops {
+							blinded_hops.push(BlindedHop {
+								blinded_node_id: PublicKey::from_slice(&[2; 33]).unwrap(),
+								encrypted_payload: Vec::new()
+							});
+						}
+						last_hops.push((payinfo, BlindedPath {
+							introduction_node_id: *intro_node_id,
+							blinding_point: PublicKey::from_slice(&[2; 33]).unwrap(),
+							blinded_hops,
+						}));
+					}
+				}
+				let mut features = Bolt12InvoiceFeatures::empty();
+				features.set_basic_mpp_optional();
+				let scorer = ProbabilisticScorer::new(ProbabilisticScoringDecayParameters::default(), &net_graph, &logger);
+				let random_seed_bytes: [u8; 32] = [get_slice!(1)[0]; 32];
+				let final_value_msat = slice_to_be64(get_slice!(8));
+				let _final_cltv_expiry_delta = slice_to_be32(get_slice!(4)); // for symmetry with non-blinded case
+				let route_params = RouteParameters {
+					payment_params: PaymentParameters::blinded(last_hops.clone())
+						.with_bolt12_features(features.clone()).unwrap(),
+					final_value_msat,
+				};
+				let _ = find_route(&our_pubkey, &route_params, &net_graph,
+					first_hops.map(|c| c.iter().collect::<Vec<_>>()).as_ref().map(|a| a.as_slice()),
+					&logger, &scorer, &ProbabilisticScoringFeeParameters::default(), &random_seed_bytes);
+			}
 		}
 	}
 }

lightning/src/blinded_path/mod.rs

@@ -36,26 +36,26 @@ pub struct BlindedPath {
 	/// message or payment's next hop and forward it along.
 	///
 	/// [`encrypted_payload`]: BlindedHop::encrypted_payload
-	pub(crate) introduction_node_id: PublicKey,
+	pub introduction_node_id: PublicKey,
 	/// Used by the introduction node to decrypt its [`encrypted_payload`] to forward the onion
 	/// message or payment.
 	///
 	/// [`encrypted_payload`]: BlindedHop::encrypted_payload
-	pub(crate) blinding_point: PublicKey,
+	pub blinding_point: PublicKey,
 	/// The hops composing the blinded path.
-	pub(crate) blinded_hops: Vec<BlindedHop>,
+	pub blinded_hops: Vec<BlindedHop>,
 }
 
 /// Used to construct the blinded hops portion of a blinded path. These hops cannot be identified
 /// by outside observers and thus can be used to hide the identity of the recipient.
 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 pub struct BlindedHop {
 	/// The blinded node id of this hop in a blinded path.
-	pub(crate) blinded_node_id: PublicKey,
+	pub blinded_node_id: PublicKey,
 	/// The encrypted payload intended for this hop in a blinded path.
 	// The node sending to this blinded path will later encode this payload into the onion packet for
 	// this hop.
-	pub(crate) encrypted_payload: Vec<u8>,
+	pub encrypted_payload: Vec<u8>,
 }
 
 impl BlindedPath {

lightning/src/routing/router.rs

@@ -656,7 +656,8 @@ impl PaymentParameters {
 			.with_expiry_time(invoice.created_at().as_secs().saturating_add(invoice.relative_expiry().as_secs()))
 	}
 
-	fn blinded(blinded_route_hints: Vec<(BlindedPayInfo, BlindedPath)>) -> Self {
+	/// Creates parameters for paying to a blinded payee from the provided blinded route hints.
+	pub fn blinded(blinded_route_hints: Vec<(BlindedPayInfo, BlindedPath)>) -> Self {
 		Self {
 			payee: Payee::Blinded { route_hints: blinded_route_hints, features: None },
 			expiry_time: None,