From: Jeffrey Czyz <jkczyz@gmail.com>
Date: Wed, 22 May 2024 21:35:57 +0000 (-0500)
Subject: Don't use compact blinded paths for reply paths
X-Git-Tag: v0.0.124-beta~93^2~4
X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=411b9b43f6089b1482eb9831742bf5ecb8238e0d;p=rust-lightning

Don't use compact blinded paths for reply paths

There's no need to save space when creating reply paths since they are
part of onion messages rather than in QR codes. Use normal blinded paths
for these instead as they are less likely to become invalid in case of
channel closure.
---

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index 691391941..391f5b330 100644
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -8270,7 +8270,8 @@ 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 = $self.create_compact_blinded_path()
+			.map_err(|_| Bolt12SemanticError::MissingPaths)?;
 		let builder = OfferBuilder::deriving_signing_pubkey(
 			node_id, expanded_key, entropy, secp_ctx
 		)
@@ -8337,7 +8338,8 @@ macro_rules! create_refund_builder { ($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 path = $self.create_compact_blinded_path()
+			.map_err(|_| Bolt12SemanticError::MissingPaths)?;
 		let builder = RefundBuilder::deriving_payer_id(
 			node_id, expanded_key, entropy, secp_ctx, amount_msats, payment_id
 		)?
@@ -8686,13 +8688,31 @@ where
 		inbound_payment::get_payment_preimage(payment_hash, payment_secret, &self.inbound_payment_key)
 	}
 
-	/// Creates a blinded path by delegating to [`MessageRouter::create_compact_blinded_paths`].
+	/// 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, ()> {
 		let recipient = self.get_our_node_id();
 		let secp_ctx = &self.secp_ctx;
 
+		let peers = self.per_peer_state.read().unwrap()
+			.iter()
+			.filter(|(_, peer)| peer.lock().unwrap().latest_features.supports_onion_messages())
+			.map(|(node_id, _)| *node_id)
+			.collect::<Vec<_>>();
+
+		self.router
+			.create_blinded_paths(recipient, peers, secp_ctx)
+			.and_then(|paths| paths.into_iter().next().ok_or(()))
+	}
+
+	/// Creates a blinded path by delegating to [`MessageRouter::create_compact_blinded_paths`].
+	///
+	/// Errors if the `MessageRouter` errors or returns an empty `Vec`.
+	fn create_compact_blinded_path(&self) -> Result<BlindedPath, ()> {
+		let recipient = self.get_our_node_id();
+		let secp_ctx = &self.secp_ctx;
+
 		let peers = self.per_peer_state.read().unwrap()
 			.iter()
 			.map(|(node_id, peer_state)| (node_id, peer_state.lock().unwrap()))
diff --git a/lightning/src/ln/offers_tests.rs b/lightning/src/ln/offers_tests.rs
index eedd82c56..5594c8ba9 100644
--- a/lightning/src/ln/offers_tests.rs
+++ b/lightning/src/ln/offers_tests.rs
@@ -427,11 +427,9 @@ fn creates_and_pays_for_offer_using_two_hop_blinded_path() {
 			payer_note_truncated: None,
 		},
 	});
-	let introduction_node_id = resolve_introduction_node(alice, &reply_path);
 	assert_eq!(invoice_request.amount_msats(), None);
 	assert_ne!(invoice_request.payer_id(), david_id);
-	assert_eq!(introduction_node_id, charlie_id);
-	assert!(matches!(reply_path.introduction_node, IntroductionNode::DirectedShortChannelId(..)));
+	assert_eq!(reply_path.introduction_node, IntroductionNode::NodeId(charlie_id));
 
 	let onion_message = alice.onion_messenger.next_onion_message_for_peer(charlie_id).unwrap();
 	charlie.onion_messenger.handle_onion_message(&alice_id, &onion_message);
@@ -582,11 +580,9 @@ fn creates_and_pays_for_offer_using_one_hop_blinded_path() {
 			payer_note_truncated: None,
 		},
 	});
-	let introduction_node_id = resolve_introduction_node(alice, &reply_path);
 	assert_eq!(invoice_request.amount_msats(), None);
 	assert_ne!(invoice_request.payer_id(), bob_id);
-	assert_eq!(introduction_node_id, bob_id);
-	assert!(matches!(reply_path.introduction_node, IntroductionNode::DirectedShortChannelId(..)));
+	assert_eq!(reply_path.introduction_node, IntroductionNode::NodeId(bob_id));
 
 	let onion_message = alice.onion_messenger.next_onion_message_for_peer(bob_id).unwrap();
 	bob.onion_messenger.handle_onion_message(&alice_id, &onion_message);