Allow create_blinded_paths function to take Recipient Data as a field

1. Recipient Data is intended to be sent along with the reply_path
   provided to the counterparty.
2. This commit introduces recipient data in the create_blinded_path
   flow, optionally appending it within the created reply_path.
3. Also update the test, to test the new added feature.

Author: shaavan

fuzz/src/chanmon_consistency.rs

@@ -31,7 +31,7 @@ use bitcoin::hashes::sha256d::Hash as Sha256dHash;
 use bitcoin::hash_types::{BlockHash, WPubkeyHash};
 
 use lightning::blinded_path::BlindedPath;
-use lightning::blinded_path::message::ForwardNode;
+use lightning::blinded_path::message::{ForwardNode, RecipientData};
 use lightning::blinded_path::payment::ReceiveTlvs;
 use lightning::chain;
 use lightning::chain::{BestBlock, ChannelMonitorUpdateStatus, chainmonitor, channelmonitor, Confirm, Watch};
@@ -120,7 +120,7 @@ impl MessageRouter for FuzzRouter {
 	}
 
 	fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
-		&self, _recipient: PublicKey, _peers: Vec<ForwardNode>, _secp_ctx: &Secp256k1<T>,
+		&self, _recipient: PublicKey, _recipient_data: Option<RecipientData>, _peers: Vec<ForwardNode>, _secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedPath>, ()> {
 		unreachable!()
 	}

fuzz/src/full_stack.rs

@@ -28,7 +28,7 @@ use bitcoin::hashes::sha256d::Hash as Sha256dHash;
 use bitcoin::hash_types::{Txid, BlockHash, WPubkeyHash};
 
 use lightning::blinded_path::BlindedPath;
-use lightning::blinded_path::message::ForwardNode;
+use lightning::blinded_path::message::{ForwardNode, RecipientData};
 use lightning::blinded_path::payment::ReceiveTlvs;
 use lightning::chain;
 use lightning::chain::{BestBlock, ChannelMonitorUpdateStatus, Confirm, Listen};
@@ -158,7 +158,7 @@ impl MessageRouter for FuzzRouter {
 	}
 
 	fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
-		&self, _recipient: PublicKey, _peers: Vec<ForwardNode>, _secp_ctx: &Secp256k1<T>,
+		&self, _recipient: PublicKey, _recipient_data: Option<RecipientData>, _peers: Vec<ForwardNode>, _secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedPath>, ()> {
 		unreachable!()
 	}

fuzz/src/invoice_request_deser.rs

@@ -85,8 +85,8 @@ fn build_response<T: secp256k1::Signing + secp256k1::Verification>(
 		],
 	];
 	let paths = vec![
-		BlindedPath::new_for_message(&intermediate_nodes[0], pubkey(42), &entropy_source, secp_ctx).unwrap(),
-		BlindedPath::new_for_message(&intermediate_nodes[1], pubkey(42), &entropy_source, secp_ctx).unwrap(),
+		BlindedPath::new_for_message(&intermediate_nodes[0], pubkey(42), None, &entropy_source, secp_ctx).unwrap(),
+		BlindedPath::new_for_message(&intermediate_nodes[1], pubkey(42), None, &entropy_source, secp_ctx).unwrap(),
 	];
 
 	let payinfo = vec![

fuzz/src/onion_message.rs

@@ -89,7 +89,8 @@ impl MessageRouter for TestMessageRouter {
 	}
 
 	fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
-		&self, _recipient: PublicKey, _peers: Vec<ForwardNode>, _secp_ctx: &Secp256k1<T>,
+		&self, _recipient: PublicKey, _recipient_data: Option<RecipientData>,
+		_peers: Vec<ForwardNode>, _secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedPath>, ()> {
 		unreachable!()
 	}

fuzz/src/refund_deser.rs

@@ -74,8 +74,8 @@ fn build_response<T: secp256k1::Signing + secp256k1::Verification>(
 		],
 	];
 	let paths = vec![
-		BlindedPath::new_for_message(&intermediate_nodes[0], pubkey(42), &entropy_source, secp_ctx).unwrap(),
-		BlindedPath::new_for_message(&intermediate_nodes[1], pubkey(42), &entropy_source, secp_ctx).unwrap(),
+		BlindedPath::new_for_message(&intermediate_nodes[0], pubkey(42), None, &entropy_source, secp_ctx).unwrap(),
+		BlindedPath::new_for_message(&intermediate_nodes[1], pubkey(42), None, &entropy_source, secp_ctx).unwrap(),
 	];
 
 	let payinfo = vec![

lightning/src/blinded_path/message.rs

@@ -112,10 +112,11 @@ impl Writeable for ReceiveTlvs {
 /// Construct blinded onion message hops for the given `intermediate_nodes` and `recipient_node_id`.
 pub(super) fn blinded_hops<T: secp256k1::Signing + secp256k1::Verification>(
 	secp_ctx: &Secp256k1<T>, intermediate_nodes: &[ForwardNode], recipient_node_id: PublicKey,
-	session_priv: &SecretKey
+	recipient_data: Option<RecipientData>, session_priv: &SecretKey
 ) -> Result<Vec<BlindedHop>, secp256k1::Error> {
 	let pks = intermediate_nodes.iter().map(|node| &node.node_id)
 		.chain(core::iter::once(&recipient_node_id));
+	let recipient_data = recipient_data.unwrap_or(RecipientData::new());
 	let tlvs = pks.clone()
 		.skip(1) // The first node's TLVs contains the next node's pubkey
 		.zip(intermediate_nodes.iter().map(|node| node.short_channel_id))
@@ -124,7 +125,7 @@ pub(super) fn blinded_hops<T: secp256k1::Signing + secp256k1::Verification>(
 			None => NextMessageHop::NodeId(*pubkey),
 		})
 		.map(|next_hop| ControlTlvs::Forward(ForwardTlvs { next_hop, next_blinding_override: None }))
-		.chain(core::iter::once(ControlTlvs::Receive(ReceiveTlvs { path_id: None, recipient_data: RecipientData::new() })));
+		.chain(core::iter::once(ControlTlvs::Receive(ReceiveTlvs { path_id: None, recipient_data })));
 
 	utils::construct_blinded_hops(secp_ctx, pks, tlvs, session_priv)
 }

lightning/src/blinded_path/mod.rs

@@ -16,6 +16,7 @@ pub(crate) mod utils;
 use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
 use core::ops::Deref;
 
+use crate::blinded_path::message::RecipientData;
 use crate::ln::msgs::DecodeError;
 use crate::offers::invoice::BlindedPayInfo;
 use crate::routing::gossip::{NodeId, ReadOnlyNetworkGraph};
@@ -123,9 +124,9 @@ pub struct BlindedHop {
 impl BlindedPath {
 	/// Create a one-hop blinded path for a message.
 	pub fn one_hop_for_message<ES: Deref, T: secp256k1::Signing + secp256k1::Verification>(
-		recipient_node_id: PublicKey, entropy_source: ES, secp_ctx: &Secp256k1<T>
+		recipient_node_id: PublicKey, recipient_data: Option<RecipientData>, entropy_source: ES, secp_ctx: &Secp256k1<T>
 	) -> Result<Self, ()> where ES::Target: EntropySource {
-		Self::new_for_message(&[], recipient_node_id, entropy_source, secp_ctx)
+		Self::new_for_message(&[], recipient_node_id, recipient_data, entropy_source, secp_ctx)
 	}
 
 	/// Create a blinded path for an onion message, to be forwarded along `node_pks`. The last node
@@ -135,7 +136,7 @@ impl BlindedPath {
 	//  TODO: make all payloads the same size with padding + add dummy hops
 	pub fn new_for_message<ES: Deref, T: secp256k1::Signing + secp256k1::Verification>(
 		intermediate_nodes: &[message::ForwardNode], recipient_node_id: PublicKey,
-		entropy_source: ES, secp_ctx: &Secp256k1<T>
+		recipient_data: Option<RecipientData>, entropy_source: ES, secp_ctx: &Secp256k1<T>
 	) -> Result<Self, ()> where ES::Target: EntropySource {
 		let introduction_node = IntroductionNode::NodeId(
 			intermediate_nodes.first().map_or(recipient_node_id, |n| n.node_id)
@@ -147,7 +148,8 @@ impl BlindedPath {
 			introduction_node,
 			blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
 			blinded_hops: message::blinded_hops(
-				secp_ctx, intermediate_nodes, recipient_node_id, &blinding_secret,
+				secp_ctx, intermediate_nodes, recipient_node_id, recipient_data,
+				&blinding_secret,
 			).map_err(|_| ())?,
 		})
 	}

lightning/src/ln/channelmanager.rs

@@ -8573,7 +8573,7 @@ macro_rules! create_offer_builder { ($self: ident, $builder: ty) => {
 		let entropy = &*$self.entropy_source;
 		let secp_ctx = &$self.secp_ctx;
 
-		let path = $self.create_blinded_path().map_err(|_| Bolt12SemanticError::MissingPaths)?;
+		let path = $self.create_blinded_path(None).map_err(|_| Bolt12SemanticError::MissingPaths)?;
 		let builder = OfferBuilder::deriving_signing_pubkey(
 			node_id, expanded_key, entropy, secp_ctx
 		)
@@ -8640,7 +8640,11 @@ macro_rules! create_refund_builder { ($self: ident, $builder: ty) => {
 		let entropy = &*$self.entropy_source;
 		let secp_ctx = &$self.secp_ctx;
 
-		let path = $self.create_blinded_path().map_err(|_| Bolt12SemanticError::MissingPaths)?;
+		let recipient_data = RecipientData {
+			payment_id: Some(payment_id)
+		};
+
+		let path = $self.create_blinded_path(Some(recipient_data)).map_err(|_| Bolt12SemanticError::MissingPaths)?;
 		let builder = RefundBuilder::deriving_payer_id(
 			node_id, expanded_key, entropy, secp_ctx, amount_msats, payment_id
 		)?
@@ -8763,7 +8767,10 @@ where
 			Some(payer_note) => builder.payer_note(payer_note),
 		};
 		let invoice_request = builder.build_and_sign()?;
-		let reply_path = self.create_blinded_path().map_err(|_| Bolt12SemanticError::MissingPaths)?;
+		let recipient_data = RecipientData {
+			payment_id: Some(payment_id)
+		};
+		let reply_path = self.create_blinded_path(Some(recipient_data)).map_err(|_| Bolt12SemanticError::MissingPaths)?;
 
 		let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
 
@@ -8863,7 +8870,7 @@ where
 				)?;
 				let builder: InvoiceBuilder<DerivedSigningPubkey> = builder.into();
 				let invoice = builder.allow_mpp().build_and_sign(secp_ctx)?;
-				let reply_path = self.create_blinded_path()
+				let reply_path = self.create_blinded_path(None)
 					.map_err(|_| Bolt12SemanticError::MissingPaths)?;
 
 				let mut pending_offers_messages = self.pending_offers_messages.lock().unwrap();
@@ -8992,7 +8999,7 @@ where
 	/// Creates a blinded path by delegating to [`MessageRouter::create_blinded_paths`].
 	///
 	/// Errors if the `MessageRouter` errors or returns an empty `Vec`.
-	fn create_blinded_path(&self) -> Result<BlindedPath, ()> {
+	fn create_blinded_path(&self, recipient_data: Option<RecipientData>) -> Result<BlindedPath, ()> {
 		let recipient = self.get_our_node_id();
 		let secp_ctx = &self.secp_ctx;
 
@@ -9011,7 +9018,7 @@ where
 			.collect::<Vec<_>>();
 
 		self.router
-			.create_blinded_paths(recipient, peers, secp_ctx)
+			.create_blinded_paths(recipient, recipient_data, peers, secp_ctx)
 			.and_then(|paths| paths.into_iter().next().ok_or(()))
 	}
 

lightning/src/ln/offers_tests.rs

@@ -1018,6 +1018,16 @@ fn fails_sending_invoice_without_blinded_payment_paths_for_offer() {
 
 	let invoice_error = extract_invoice_error(david, &onion_message);
 	assert_eq!(invoice_error, InvoiceError::from(Bolt12SemanticError::MissingPaths));
+
+	// Confirm that david drops this failed payment from his pending outbound payments.
+	let events = david.node.get_and_clear_pending_events();
+	assert_eq!(events.len(), 1);
+	match events[0] {
+		Event::InvoiceRequestFailed { payment_id: pay_id} => {
+			assert_eq!(pay_id, payment_id)
+		},
+		_ => panic!("Unexpected Event"),
+	}
 }
 
 #[test]

lightning/src/onion_message/functional_tests.rs

@@ -359,7 +359,7 @@ fn one_blinded_hop() {
 	let test_msg = TestCustomMessage::Pong;
 
 	let secp_ctx = Secp256k1::new();
-	let blinded_path = BlindedPath::new_for_message(&[], nodes[1].node_id, &*nodes[1].entropy_source, &secp_ctx).unwrap();
+	let blinded_path = BlindedPath::new_for_message(&[], nodes[1].node_id, None, &*nodes[1].entropy_source, &secp_ctx).unwrap();
 	let destination = Destination::BlindedPath(blinded_path);
 	nodes[0].messenger.send_onion_message(test_msg, destination, None).unwrap();
 	nodes[1].custom_message_handler.expect_message(TestCustomMessage::Pong);
@@ -373,7 +373,7 @@ fn two_unblinded_two_blinded() {
 
 	let secp_ctx = Secp256k1::new();
 	let intermediate_nodes = [ForwardNode { node_id: nodes[3].node_id, short_channel_id: None }];
-	let blinded_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[4].node_id, &*nodes[4].entropy_source, &secp_ctx).unwrap();
+	let blinded_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[4].node_id, None, &*nodes[4].entropy_source, &secp_ctx).unwrap();
 	let path = OnionMessagePath {
 		intermediate_nodes: vec![nodes[1].node_id, nodes[2].node_id],
 		destination: Destination::BlindedPath(blinded_path),
@@ -395,7 +395,7 @@ fn three_blinded_hops() {
 		ForwardNode { node_id: nodes[1].node_id, short_channel_id: None },
 		ForwardNode { node_id: nodes[2].node_id, short_channel_id: None },
 	];
-	let blinded_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[3].node_id, &*nodes[3].entropy_source, &secp_ctx).unwrap();
+	let blinded_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[3].node_id, None, &*nodes[3].entropy_source, &secp_ctx).unwrap();
 	let destination = Destination::BlindedPath(blinded_path);
 
 	nodes[0].messenger.send_onion_message(test_msg, destination, None).unwrap();
@@ -418,7 +418,7 @@ fn async_response_over_one_blinded_hop() {
 
 	// 3. Simulate the creation of a Blinded Reply path provided by Bob.
 	let secp_ctx = Secp256k1::new();
-	let reply_path = BlindedPath::new_for_message(&[], nodes[1].node_id, &*nodes[1].entropy_source, &secp_ctx).unwrap();
+	let reply_path = BlindedPath::new_for_message(&[], nodes[1].node_id, None, &*nodes[1].entropy_source, &secp_ctx).unwrap();
 
 	// 4. Create a responder using the reply path for Alice.
 	let responder = Some(Responder::new(reply_path, path_id));
@@ -454,7 +454,7 @@ fn async_response_with_reply_path_succeeds() {
 	// Alice receives a message from Bob with an added reply_path for responding back.
 	let message = TestCustomMessage::Ping;
 	let path_id = Some([2; 32]);
-	let reply_path = BlindedPath::new_for_message(&[], bob.node_id, &*bob.entropy_source, &secp_ctx).unwrap();
+	let reply_path = BlindedPath::new_for_message(&[], bob.node_id, None, &*bob.entropy_source, &secp_ctx).unwrap();
 
 	// Alice asynchronously responds to Bob, expecting a response back from him.
 	let responder = Responder::new(reply_path, path_id);
@@ -491,7 +491,7 @@ fn async_response_with_reply_path_fails() {
 	// Alice receives a message from Bob with an added reply_path for responding back.
 	let message = TestCustomMessage::Ping;
 	let path_id = Some([2; 32]);
-	let reply_path = BlindedPath::new_for_message(&[], bob.node_id, &*bob.entropy_source, &secp_ctx).unwrap();
+	let reply_path = BlindedPath::new_for_message(&[], bob.node_id, None, &*bob.entropy_source, &secp_ctx).unwrap();
 
 	// Alice tries to asynchronously respond to Bob, but fails because the nodes are unannounced.
 	// Therefore, the reply_path cannot be used for the response.
@@ -534,7 +534,7 @@ fn we_are_intro_node() {
 		ForwardNode { node_id: nodes[0].node_id, short_channel_id: None },
 		ForwardNode { node_id: nodes[1].node_id, short_channel_id: None },
 	];
-	let blinded_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[2].node_id, &*nodes[2].entropy_source, &secp_ctx).unwrap();
+	let blinded_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[2].node_id, None, &*nodes[2].entropy_source, &secp_ctx).unwrap();
 	let destination = Destination::BlindedPath(blinded_path);
 
 	nodes[0].messenger.send_onion_message(test_msg.clone(), destination, None).unwrap();
@@ -543,7 +543,7 @@ fn we_are_intro_node() {
 
 	// Try with a two-hop blinded path where we are the introduction node.
 	let intermediate_nodes = [ForwardNode { node_id: nodes[0].node_id, short_channel_id: None }];
-	let blinded_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[1].node_id, &*nodes[1].entropy_source, &secp_ctx).unwrap();
+	let blinded_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[1].node_id, None, &*nodes[1].entropy_source, &secp_ctx).unwrap();
 	let destination = Destination::BlindedPath(blinded_path);
 	nodes[0].messenger.send_onion_message(test_msg, destination, None).unwrap();
 	nodes[1].custom_message_handler.expect_message(TestCustomMessage::Pong);
@@ -559,7 +559,7 @@ fn invalid_blinded_path_error() {
 
 	let secp_ctx = Secp256k1::new();
 	let intermediate_nodes = [ForwardNode { node_id: nodes[1].node_id, short_channel_id: None }];
-	let mut blinded_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[2].node_id, &*nodes[2].entropy_source, &secp_ctx).unwrap();
+	let mut blinded_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[2].node_id, None, &*nodes[2].entropy_source, &secp_ctx).unwrap();
 	blinded_path.blinded_hops.clear();
 	let destination = Destination::BlindedPath(blinded_path);
 	let err = nodes[0].messenger.send_onion_message(test_msg, destination, None).unwrap_err();
@@ -582,7 +582,7 @@ fn reply_path() {
 		ForwardNode { node_id: nodes[2].node_id, short_channel_id: None },
 		ForwardNode { node_id: nodes[1].node_id, short_channel_id: None },
 	];
-	let reply_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[0].node_id, &*nodes[0].entropy_source, &secp_ctx).unwrap();
+	let reply_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[0].node_id, None, &*nodes[0].entropy_source, &secp_ctx).unwrap();
 	nodes[0].messenger.send_onion_message_using_path(path, test_msg.clone(), Some(reply_path)).unwrap();
 	nodes[3].custom_message_handler.expect_message(TestCustomMessage::Ping);
 	pass_along_path(&nodes);
@@ -596,13 +596,13 @@ fn reply_path() {
 		ForwardNode { node_id: nodes[1].node_id, short_channel_id: None },
 		ForwardNode { node_id: nodes[2].node_id, short_channel_id: None },
 	];
-	let blinded_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[3].node_id, &*nodes[3].entropy_source, &secp_ctx).unwrap();
+	let blinded_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[3].node_id, None, &*nodes[3].entropy_source, &secp_ctx).unwrap();
 	let destination = Destination::BlindedPath(blinded_path);
 	let intermediate_nodes = [
 		ForwardNode { node_id: nodes[2].node_id, short_channel_id: None },
 		ForwardNode { node_id: nodes[1].node_id, short_channel_id: None },
 	];
-	let reply_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[0].node_id, &*nodes[0].entropy_source, &secp_ctx).unwrap();
+	let reply_path = BlindedPath::new_for_message(&intermediate_nodes, nodes[0].node_id, None, &*nodes[0].entropy_source, &secp_ctx).unwrap();
 
 	nodes[0].messenger.send_onion_message(test_msg, destination, Some(reply_path)).unwrap();
 	nodes[3].custom_message_handler.expect_message(TestCustomMessage::Ping);
@@ -684,7 +684,7 @@ fn requests_peer_connection_for_buffered_messages() {
 
 	let intermediate_nodes = [ForwardNode { node_id: nodes[1].node_id, short_channel_id: None }];
 	let blinded_path = BlindedPath::new_for_message(
-		&intermediate_nodes, nodes[2].node_id, &*nodes[0].entropy_source, &secp_ctx
+		&intermediate_nodes, nodes[2].node_id, None, &*nodes[0].entropy_source, &secp_ctx
 	).unwrap();
 	let destination = Destination::BlindedPath(blinded_path);
 
@@ -722,7 +722,7 @@ fn drops_buffered_messages_waiting_for_peer_connection() {
 
 	let intermediate_nodes = [ForwardNode { node_id: nodes[1].node_id, short_channel_id: None }];
 	let blinded_path = BlindedPath::new_for_message(
-		&intermediate_nodes, nodes[2].node_id, &*nodes[0].entropy_source, &secp_ctx
+		&intermediate_nodes, nodes[2].node_id, None, &*nodes[0].entropy_source, &secp_ctx
 	).unwrap();
 	let destination = Destination::BlindedPath(blinded_path);
 
@@ -772,7 +772,7 @@ fn intercept_offline_peer_oms() {
 	let secp_ctx = Secp256k1::new();
 	let intermediate_nodes = [ForwardNode { node_id: nodes[1].node_id, short_channel_id: None }];
 	let blinded_path = BlindedPath::new_for_message(
-		&intermediate_nodes, nodes[2].node_id, &*nodes[2].entropy_source, &secp_ctx
+		&intermediate_nodes, nodes[2].node_id, None, &*nodes[2].entropy_source, &secp_ctx
 	).unwrap();
 	let destination = Destination::BlindedPath(blinded_path);