Remove create_compact_blinded_paths

1. The `params` parameter now allows specifying the type of blinded
   path to be created, enabling a single function to handle the processing
   for both compact and full-length blinded paths.
2. This change renders the `create_compact_blinded_paths` function redundant,
   leading to its removal.
3. With this commit, the blinded path creation process is streamlined to
   a single function capable of creating any type of blinded path.

Author: shaavan

fuzz/src/chanmon_consistency.rs

@@ -33,7 +33,7 @@ use bitcoin::hashes::sha256d::Hash as Sha256dHash;
 use bitcoin::hashes::Hash as TraitImport;
 use bitcoin::WPubkeyHash;
 
-use lightning::blinded_path::message::{BlindedMessagePath, MessageContext};
+use lightning::blinded_path::message::{BlindedMessagePath, MessageContext, MessageForwardNode};
 use lightning::blinded_path::payment::{BlindedPaymentPath, ReceiveTlvs};
 use lightning::chain;
 use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
@@ -144,7 +144,7 @@ impl MessageRouter for FuzzRouter {
 
 	fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
 		&self, _params: BlindedPathParams, _recipient: PublicKey, _context: MessageContext,
-		_peers: Vec<PublicKey>, _secp_ctx: &Secp256k1<T>,
+		_peers: Vec<MessageForwardNode>, _secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
 		unreachable!()
 	}

fuzz/src/full_stack.rs

@@ -30,7 +30,7 @@ use bitcoin::hashes::Hash as _;
 use bitcoin::hex::FromHex;
 use bitcoin::WPubkeyHash;
 
-use lightning::blinded_path::message::{BlindedMessagePath, MessageContext};
+use lightning::blinded_path::message::{BlindedMessagePath, MessageContext, MessageForwardNode};
 use lightning::blinded_path::payment::{BlindedPaymentPath, ReceiveTlvs};
 use lightning::chain;
 use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
@@ -179,7 +179,7 @@ impl MessageRouter for FuzzRouter {
 
 	fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
 		&self, _params: BlindedPathParams, _recipient: PublicKey, _context: MessageContext,
-		_peers: Vec<PublicKey>, _secp_ctx: &Secp256k1<T>,
+		_peers: Vec<MessageForwardNode>, _secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
 		unreachable!()
 	}

fuzz/src/onion_message.rs

@@ -5,7 +5,9 @@ use bitcoin::secp256k1::ecdsa::RecoverableSignature;
 use bitcoin::secp256k1::schnorr;
 use bitcoin::secp256k1::{self, PublicKey, Scalar, Secp256k1, SecretKey};
 
-use lightning::blinded_path::message::{BlindedMessagePath, MessageContext, OffersContext};
+use lightning::blinded_path::message::{
+	BlindedMessagePath, MessageContext, MessageForwardNode, OffersContext,
+};
 use lightning::blinded_path::EmptyNodeIdLookUp;
 use lightning::ln::features::InitFeatures;
 use lightning::ln::msgs::{self, DecodeError, OnionMessageHandler};
@@ -97,7 +99,7 @@ impl MessageRouter for TestMessageRouter {
 
 	fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
 		&self, _params: BlindedPathParams, _recipient: PublicKey, _context: MessageContext,
-		_peers: Vec<PublicKey>, _secp_ctx: &Secp256k1<T>,
+		_peers: Vec<MessageForwardNode>, _secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
 		unreachable!()
 	}

lightning/src/ln/channelmanager.rs

@@ -33,7 +33,7 @@ use bitcoin::secp256k1::Secp256k1;
 use bitcoin::{secp256k1, Sequence};
 
 use crate::events::FundingInfo;
-use crate::blinded_path::message::{MessageContext, OffersContext};
+use crate::blinded_path::message::{MessageContext, MessageForwardNode, OffersContext};
 use crate::blinded_path::NodeIdLookUp;
 use crate::blinded_path::message::BlindedMessagePath;
 use crate::blinded_path::payment::{BlindedPaymentPath, Bolt12OfferContext, Bolt12RefundContext, PaymentConstraints, PaymentContext, ReceiveTlvs};
@@ -2499,9 +2499,7 @@ const MAX_NO_CHANNEL_PEERS: usize = 250;
 /// short-lived, while anything with a greater expiration is considered long-lived.
 ///
 /// Using [`ChannelManager::create_offer_builder`] or [`ChannelManager::create_refund_builder`],
-/// will included a [`BlindedMessagePath`] created using:
-/// - [`MessageRouter::create_compact_blinded_paths`] when short-lived, and
-/// - [`MessageRouter::create_blinded_paths`] when long-lived.
+/// will included a [`BlindedMessagePath`] created using [`MessageRouter::create_blinded_paths`].
 ///
 /// Using compact [`BlindedMessagePath`]s may provide better privacy as the [`MessageRouter`] could select
 /// more hops. However, since they use short channel ids instead of pubkeys, they are more likely to
@@ -9384,7 +9382,23 @@ where
 			.map(|(node_id, peer_state)| (node_id, peer_state.lock().unwrap()))
 			.filter(|(_, peer)| peer.is_connected)
 			.filter(|(_, peer)| peer.latest_features.supports_onion_messages())
-			.map(|(node_id, _)| *node_id)
+			.map(|(node_id, peer)| {
+				if params.is_compact {
+					MessageForwardNode {
+						node_id: *node_id,
+						short_channel_id: peer.channel_by_id
+							.iter()
+							.filter(|(_, channel)| channel.context().is_usable())
+							.min_by_key(|(_, channel)| channel.context().channel_creation_height)
+							.and_then(|(_, channel)| channel.context().get_short_channel_id()),
+					}
+				} else {
+					MessageForwardNode {
+						node_id: *node_id,
+						short_channel_id: None,
+					}
+				}
+			})
 			.collect::<Vec<_>>();
 
 		self.router

lightning/src/onion_message/messenger.rs

@@ -175,7 +175,7 @@ for OnionMessenger<ES, NS, L, NL, MR, OMH, APH, CMH> where
 /// #         })
 /// #     }
 /// #     fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
-/// #        &self, _params: BlindedPathParams, _recipient: PublicKey, _context: MessageContext, _peers: Vec<PublicKey>, _secp_ctx: &Secp256k1<T>
+/// #         &self, _params: BlindedPathParams, _recipient: PublicKey, _context: MessageContext, _peers: Vec<MessageForwardNode>, _secp_ctx: &Secp256k1<T>
 /// #     ) -> Result<Vec<BlindedMessagePath>, ()> {
 /// #         unreachable!()
 /// #     }
@@ -475,36 +475,8 @@ pub trait MessageRouter {
 	fn create_blinded_paths<
 		T: secp256k1::Signing + secp256k1::Verification
 	>(
-		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
+		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext, peers: Vec<MessageForwardNode>, secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()>;
-
-	/// Creates compact [`BlindedMessagePath`]s to the `recipient` node. The nodes in `peers` are
-	/// assumed to be direct peers with the `recipient`.
-	///
-	/// Compact blinded paths use short channel ids instead of pubkeys for a smaller serialization,
-	/// which is beneficial when a QR code is used to transport the data. The SCID is passed using
-	/// a [`MessageForwardNode`] but may be `None` for graceful degradation.
-	///
-	/// Implementations using additional intermediate nodes are responsible for using a
-	/// [`MessageForwardNode`] with `Some` short channel id, if possible. Similarly, implementations
-	/// should call [`BlindedMessagePath::use_compact_introduction_node`].
-	///
-	/// The provided implementation simply delegates to [`MessageRouter::create_blinded_paths`],
-	/// ignoring the short channel ids.
-	fn create_compact_blinded_paths<
-		T: secp256k1::Signing + secp256k1::Verification
-	>(
-		&self, recipient: PublicKey, context: MessageContext,
-		peers: Vec<MessageForwardNode>, secp_ctx: &Secp256k1<T>,
-	) -> Result<Vec<BlindedMessagePath>, ()> {
-		let peers = peers
-			.into_iter()
-			.map(|MessageForwardNode { node_id, short_channel_id: _ }| node_id)
-			.collect();
-
-		let params = BlindedPathParams::new(true);
-		self.create_blinded_paths(params, recipient, context, peers, secp_ctx)
-	}
 }
 
 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
@@ -638,21 +610,8 @@ where
 		T: secp256k1::Signing + secp256k1::Verification
 	>(
 		params: BlindedPathParams, network_graph: &G, recipient: PublicKey, context: MessageContext,
-		peers: Vec<PublicKey>, entropy_source: &ES, secp_ctx: &Secp256k1<T>,
-	) -> Result<Vec<BlindedMessagePath>, ()> {
-		let peers = peers
-			.into_iter()
-			.map(|node_id| MessageForwardNode { node_id, short_channel_id: None });
-		Self::create_blinded_paths_from_iter(params, network_graph, recipient, context, peers.into_iter(), entropy_source, secp_ctx)
-	}
-
-	pub(crate) fn create_compact_blinded_paths<
-		T: secp256k1::Signing + secp256k1::Verification
-	>(
-		network_graph: &G, recipient: PublicKey, context: MessageContext,
 		peers: Vec<MessageForwardNode>, entropy_source: &ES, secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
-		let params = BlindedPathParams::new(true);
 		Self::create_blinded_paths_from_iter(params, network_graph, recipient, context, peers.into_iter(), entropy_source, secp_ctx)
 	}
 }
@@ -671,19 +630,10 @@ where
 	fn create_blinded_paths<
 		T: secp256k1::Signing + secp256k1::Verification
 	>(
-		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
+		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext, peers: Vec<MessageForwardNode>, secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
 		Self::create_blinded_paths(params, &self.network_graph, recipient, context, peers, &self.entropy_source, secp_ctx)
 	}
-
-	fn create_compact_blinded_paths<
-		T: secp256k1::Signing + secp256k1::Verification
-	>(
-		&self, recipient: PublicKey, context: MessageContext, peers: Vec<MessageForwardNode>, secp_ctx: &Secp256k1<T>,
-	) -> Result<Vec<BlindedMessagePath>, ()> {
-		Self::create_compact_blinded_paths(&self.network_graph, recipient, context, peers, &self.entropy_source, secp_ctx)
-	}
-
 }
 
 /// A path for sending an [`OnionMessage`].
@@ -1275,7 +1225,7 @@ where
 		let peers = self.message_recipients.lock().unwrap()
 			.iter()
 			.filter(|(_, peer)| matches!(peer, OnionMessageRecipient::ConnectedPeer(_)))
-			.map(|(node_id, _ )| *node_id)
+			.map(|(node_id, _)| MessageForwardNode { node_id: *node_id, short_channel_id: None })
 			.collect::<Vec<_>>();
 
 		self.message_router

lightning/src/routing/router.rs

@@ -197,18 +197,10 @@ impl< G: Deref<Target = NetworkGraph<L>>, L: Deref, ES: Deref, S: Deref, SP: Siz
 	fn create_blinded_paths<
 		T: secp256k1::Signing + secp256k1::Verification
 	> (
-		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
+		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext, peers: Vec<MessageForwardNode>, secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
 		DefaultMessageRouter::create_blinded_paths(params, &self.network_graph, recipient, context, peers, &self.entropy_source, secp_ctx)
 	}
-
-	fn create_compact_blinded_paths<
-		T: secp256k1::Signing + secp256k1::Verification
-	> (
-		&self, recipient: PublicKey, context: MessageContext, peers: Vec<MessageForwardNode>, secp_ctx: &Secp256k1<T>,
-	) -> Result<Vec<BlindedMessagePath>, ()> {
-		DefaultMessageRouter::create_compact_blinded_paths(&self.network_graph, recipient, context, peers, &self.entropy_source, secp_ctx)
-	}
 }
 
 /// A trait defining behavior for routing a payment.

lightning/src/util/test_utils.rs

@@ -277,18 +277,9 @@ impl<'a> MessageRouter for TestRouter<'a> {
 		T: secp256k1::Signing + secp256k1::Verification
 	>(
 		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext,
-		peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
-	) -> Result<Vec<BlindedMessagePath>, ()> {
-		self.router.create_blinded_paths(params, recipient, context, peers, secp_ctx)
-	}
-
-	fn create_compact_blinded_paths<
-		T: secp256k1::Signing + secp256k1::Verification
-	>(
-		&self, recipient: PublicKey, context: MessageContext,
 		peers: Vec<MessageForwardNode>, secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
-		self.router.create_compact_blinded_paths(recipient, context, peers, secp_ctx)
+		self.router.create_blinded_paths(params, recipient, context, peers, secp_ctx)
 	}
 }
 
@@ -320,16 +311,9 @@ impl<'a> MessageRouter for TestMessageRouter<'a> {
 
 	fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
 		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext,
-		peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
-	) -> Result<Vec<BlindedMessagePath>, ()> {
-		self.inner.create_blinded_paths(params, recipient, context, peers, secp_ctx)
-	}
-
-	fn create_compact_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
-		&self, recipient: PublicKey, context: MessageContext,
 		peers: Vec<MessageForwardNode>, secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
-		self.inner.create_compact_blinded_paths(recipient, context, peers, secp_ctx)
+		self.inner.create_blinded_paths(params, recipient, context, peers, secp_ctx)
 	}
 }