Support receiving payments to blinded paths.

Error handling will be completed in later commit(s).

lightning/src/ln/blinded_payment_tests.rs

@@ -0,0 +1,60 @@
+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+use bitcoin::secp256k1::Secp256k1;
+use crate::blinded_path::BlindedPath;
+use crate::blinded_path::payment::{PaymentConstraints, ReceiveTlvs};
+use crate::ln::channelmanager::{PaymentId, RecipientOnionFields};
+use crate::ln::functional_test_utils::*;
+use crate::ln::outbound_payment::Retry;
+use crate::prelude::*;
+use crate::routing::router::{PaymentParameters, RouteParameters};
+
+#[test]
+fn one_hop_blinded_path() {
+	do_one_hop_blinded_path(true);
+	do_one_hop_blinded_path(false);
+}
+
+fn do_one_hop_blinded_path(success: bool) {
+	let chanmon_cfgs = create_chanmon_cfgs(2);
+	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+	let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+	let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+	let chan_upd = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0).0.contents;
+
+	let amt_msat = 5000;
+	let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[1], Some(amt_msat), None);
+	let payee_tlvs = ReceiveTlvs {
+		payment_secret,
+		payment_constraints: PaymentConstraints {
+			max_cltv_expiry: u32::max_value(),
+			htlc_minimum_msat: chan_upd.htlc_minimum_msat,
+		},
+	};
+	let mut secp_ctx = Secp256k1::new();
+	let blinded_path = BlindedPath::new_for_payment(
+		&[], nodes[1].node.get_our_node_id(), payee_tlvs, chan_upd.htlc_maximum_msat,
+		&chanmon_cfgs[1].keys_manager, &secp_ctx
+	).unwrap();
+
+	let route_params = RouteParameters {
+		payment_params: PaymentParameters::blinded(vec![blinded_path]),
+		final_value_msat: amt_msat
+	};
+	nodes[0].node.send_payment(payment_hash, RecipientOnionFields::spontaneous_empty(),
+	PaymentId(payment_hash.0), route_params, Retry::Attempts(0)).unwrap();
+	check_added_monitors(&nodes[0], 1);
+	pass_along_route(&nodes[0], &[&[&nodes[1]]], amt_msat, payment_hash, payment_secret);
+	if success {
+		claim_payment(&nodes[0], &[&nodes[1]], payment_preimage);
+	} else {
+		fail_payment(&nodes[0], &[&nodes[1]], payment_hash);
+	}
+}

lightning/src/ln/channelmanager.rs

@@ -22,11 +22,12 @@ use bitcoin::blockdata::transaction::Transaction;
 use bitcoin::blockdata::constants::{genesis_block, ChainHash};
 use bitcoin::network::constants::Network;
 
-use bitcoin::hashes::Hash;
+use bitcoin::hashes::{Hash, HashEngine};
+use bitcoin::hashes::hmac::{Hmac, HmacEngine};
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::hash_types::{BlockHash, Txid};
 
-use bitcoin::secp256k1::{SecretKey,PublicKey};
+use bitcoin::secp256k1::{PublicKey, Scalar, SecretKey};
 use bitcoin::secp256k1::Secp256k1;
 use bitcoin::{LockTime, secp256k1, Sequence};
 
@@ -49,7 +50,7 @@ use crate::routing::router::{BlindedTail, DefaultRouter, InFlightHtlcs, Path, Pa
 use crate::routing::scoring::{ProbabilisticScorer, ProbabilisticScoringFeeParameters};
 use crate::ln::msgs;
 use crate::ln::onion_utils;
-use crate::ln::onion_utils::HTLCFailReason;
+use crate::ln::onion_utils::{HTLCFailReason, INVALID_ONION_BLINDING};
 use crate::ln::msgs::{ChannelMessageHandler, DecodeError, LightningError};
 #[cfg(test)]
 use crate::ln::outbound_payment;
@@ -2763,13 +2764,26 @@ where
 				payment_data, keysend_preimage, custom_tlvs, amt_msat, outgoing_cltv_value, payment_metadata, ..
 			} =>
 				(payment_data, keysend_preimage, custom_tlvs, amt_msat, outgoing_cltv_value, payment_metadata),
-			msgs::InboundOnionPayload::Forward { .. } =>
+			msgs::InboundOnionPayload::BlindedReceive {
+				amt_msat, total_msat, outgoing_cltv_value, payment_secret, ..
+			} => {
+				let payment_data = msgs::FinalOnionHopData { payment_secret, total_msat };
+				(Some(payment_data), None, Vec::new(), amt_msat, outgoing_cltv_value, None)
+			}
+			msgs::InboundOnionPayload::Forward { .. } => {
 				return Err(InboundOnionErr {
 					err_code: 0x4000|22,
 					err_data: Vec::new(),
 					msg: "Got non final data with an HMAC of 0",
-				}),
-			_ => todo!()
+				})
+			},
+			msgs::InboundOnionPayload::BlindedForward { .. } => {
+				return Err(InboundOnionErr {
+					msg: "Got blinded non final data with an HMAC of 0",
+					err_code: INVALID_ONION_BLINDING,
+					err_data: vec![0; 32],
+				})
+			},
 		};
 		// final_incorrect_cltv_expiry
 		if outgoing_cltv_value > cltv_expiry {
@@ -2882,8 +2896,15 @@ where
 			return_malformed_err!("invalid ephemeral pubkey", 0x8000 | 0x4000 | 6);
 		}
 
+		let blinded_node_id_tweak = msg.blinding_point.map(|bp| {
+			let blinded_tlvs_ss = self.node_signer.ecdh(
+				Recipient::Node, &bp, None).unwrap().secret_bytes();
+			let mut hmac = HmacEngine::<Sha256>::new(b"blinded_node_id");
+			hmac.input(blinded_tlvs_ss.as_ref());
+			Scalar::from_be_bytes(Hmac::from_engine(hmac).into_inner()).unwrap()
+		});
 		let shared_secret = self.node_signer.ecdh(
-			Recipient::Node, &msg.onion_routing_packet.public_key.unwrap(), None
+			Recipient::Node, &msg.onion_routing_packet.public_key.unwrap(), blinded_node_id_tweak.as_ref()
 		).unwrap().secret_bytes();
 
 		if msg.onion_routing_packet.version != 0 {

lightning/src/ln/mod.rs

@@ -43,6 +43,9 @@ pub mod wire;
 // without the node parameter being mut. This is incorrect, and thus newer rustcs will complain
 // about an unnecessary mut. Thus, we silence the unused_mut warning in two test modules below.
 
+#[cfg(test)]
+#[allow(unused_mut)]
+mod blinded_payment_tests;
 #[cfg(test)]
 #[allow(unused_mut)]
 mod functional_tests;

lightning/src/ln/onion_utils.rs

@@ -240,6 +240,8 @@ pub(super) fn build_onion_payloads(path: &Path, total_msat: u64, mut recipient_o
 /// the hops can be of variable length.
 pub(crate) const ONION_DATA_LEN: usize = 20*65;
 
+pub(super) const INVALID_ONION_BLINDING: u16 = 0x8000 | 0x4000 | 24;
+
 #[inline]
 fn shift_slice_right(arr: &mut [u8], amt: usize) {
 	for i in (amt..arr.len()).rev() {