Introduce params Field in create_blinded_paths

1. Added a `params` field to the `create_blinded_paths` function, allowing
   users to specify Blinded Path Parameters directly.
2. This change simplifies the back-end by eliminating the need for multiple
  `create_blinded_path` variants tailored to different types of blinded paths.
3. In upcoming commits, the `create_blinded_path_using_absolute_expiry` and
  `create_compact_blinded_path` functions will be removed as they become redundant.

Author: shaavan

fuzz/src/chanmon_consistency.rs

@@ -139,7 +139,7 @@ impl MessageRouter for FuzzRouter {
 	}
 
 	fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
-		&self, _recipient: PublicKey, _context: MessageContext, _peers: Vec<PublicKey>,
+		&self, _params: BlindedPathParams, _recipient: PublicKey, _context: MessageContext, _peers: Vec<PublicKey>,
 		_secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
 		unreachable!()

fuzz/src/full_stack.rs

@@ -176,7 +176,7 @@ impl MessageRouter for FuzzRouter {
 	}
 
 	fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
-		&self, _recipient: PublicKey, _context: MessageContext, _peers: Vec<PublicKey>,
+		&self, _params: BlindedPathParams, _recipient: PublicKey, _context: MessageContext, _peers: Vec<PublicKey>,
 		_secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
 		unreachable!()

fuzz/src/onion_message.rs

@@ -96,7 +96,7 @@ impl MessageRouter for TestMessageRouter {
 	}
 
 	fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
-		&self, _recipient: PublicKey, _context: MessageContext, _peers: Vec<PublicKey>,
+		&self, _params: BlindedPathParams _recipient: PublicKey, _context: MessageContext, _peers: Vec<PublicKey>,
 		_secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
 		unreachable!()

lightning/src/ln/channelmanager.rs

@@ -70,7 +70,7 @@ use crate::offers::parse::Bolt12SemanticError;
 use crate::offers::refund::{Refund, RefundBuilder};
 use crate::offers::signer;
 use crate::onion_message::async_payments::{AsyncPaymentsMessage, HeldHtlcAvailable, ReleaseHeldHtlc, AsyncPaymentsMessageHandler};
-use crate::onion_message::messenger::{new_pending_onion_message, Destination, MessageRouter, PendingOnionMessage, Responder, ResponseInstruction};
+use crate::onion_message::messenger::{new_pending_onion_message, BlindedPathParams, Destination, MessageRouter, PendingOnionMessage, Responder, ResponseInstruction, PATHS_PLACEHOLDER};
 use crate::onion_message::offers::{OffersMessage, OffersMessageHandler};
 use crate::sign::{EntropySource, NodeSigner, Recipient, SignerProvider};
 use crate::sign::ecdsa::EcdsaChannelSigner;
@@ -8818,12 +8818,12 @@ macro_rules! create_offer_builder { ($self: ident, $builder: ty) => {
 		let nonce = Nonce::from_entropy_source(entropy);
 		let context = OffersContext::InvoiceRequest { nonce };
 		let path = $self.create_blinded_paths_using_absolute_expiry(context, absolute_expiry)
-			.and_then(|paths| paths.into_iter().next().ok_or(()))
-			.map_err(|_| Bolt12SemanticError::MissingPaths)?;
+				.and_then(|paths| paths.into_iter().next().ok_or(()))
+				.map_err(|_| Bolt12SemanticError::MissingPaths)?;
 		let builder = OfferBuilder::deriving_signing_pubkey(node_id, expanded_key, nonce, secp_ctx)
 			.chain_hash($self.chain_hash)
 			.path(path);
-
+		
 		let builder = match absolute_expiry {
 			None => builder,
 			Some(absolute_expiry) => builder.absolute_expiry(absolute_expiry),
@@ -8890,10 +8890,10 @@ macro_rules! create_refund_builder { ($self: ident, $builder: ty) => {
 
 		let nonce = Nonce::from_entropy_source(entropy);
 		let context = OffersContext::OutboundPayment { payment_id, nonce, hmac: None };
+
 		let path = $self.create_blinded_paths_using_absolute_expiry(context, Some(absolute_expiry))
 			.and_then(|paths| paths.into_iter().next().ok_or(()))
 			.map_err(|_| Bolt12SemanticError::MissingPaths)?;
-
 		let builder = RefundBuilder::deriving_payer_id(
 			node_id, expanded_key, nonce, secp_ctx, amount_msats, payment_id
 		)?
@@ -9025,8 +9025,12 @@ where
 		let invoice_request = builder.build_and_sign()?;
 
 		let hmac = signer::hmac_for_payment_id(payment_id, nonce, expanded_key);
+		let params = BlindedPathParams {
+			paths: PATHS_PLACEHOLDER,
+			is_compact: false,
+		};
 		let context = OffersContext::OutboundPayment { payment_id, nonce, hmac: Some(hmac) };
-		let reply_paths = self.create_blinded_paths(context)
+		let reply_paths = self.create_blinded_paths(params, context)
 			.map_err(|_| Bolt12SemanticError::MissingPaths)?;
 
 		let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(self);
@@ -9129,11 +9133,15 @@ where
 				)?;
 				let builder: InvoiceBuilder<DerivedSigningPubkey> = builder.into();
 				let invoice = builder.allow_mpp().build_and_sign(secp_ctx)?;
-
+				
+				let params = BlindedPathParams {
+					paths: PATHS_PLACEHOLDER,
+					is_compact: false,
+				};
 				let context = OffersContext::InboundPayment {
 					payment_hash: invoice.payment_hash(),
 				};
-				let reply_paths = self.create_blinded_paths(context)
+				let reply_paths = self.create_blinded_paths(params, context)
 					.map_err(|_| Bolt12SemanticError::MissingPaths)?;
 
 				let mut pending_offers_messages = self.pending_offers_messages.lock().unwrap();
@@ -9280,7 +9288,11 @@ where
 		if absolute_expiry.unwrap_or(Duration::MAX) <= max_short_lived_absolute_expiry {
 			self.create_compact_blinded_paths(context)
 		} else {
-			self.create_blinded_paths(context)
+			let params = BlindedPathParams {
+				paths: PATHS_PLACEHOLDER,
+				is_compact: false
+			};
+			self.create_blinded_paths(params, context)
 		}
 	}
 
@@ -9301,7 +9313,7 @@ where
 	/// [`MessageRouter::create_blinded_paths`].
 	///
 	/// Errors if the `MessageRouter` errors.
-	fn create_blinded_paths(&self, context: OffersContext) -> Result<Vec<BlindedMessagePath>, ()> {
+	fn create_blinded_paths(&self, params: BlindedPathParams, context: OffersContext) -> Result<Vec<BlindedMessagePath>, ()> {
 		let recipient = self.get_our_node_id();
 		let secp_ctx = &self.secp_ctx;
 
@@ -9314,7 +9326,7 @@ where
 			.collect::<Vec<_>>();
 
 		self.router
-			.create_blinded_paths(recipient, MessageContext::Offers(context), peers, secp_ctx)
+			.create_blinded_paths(params, recipient, MessageContext::Offers(context), peers, secp_ctx)
 			.and_then(|paths| (!paths.is_empty()).then(|| paths).ok_or(()))
 	}
 

lightning/src/onion_message/messenger.rs

@@ -151,7 +151,7 @@ for OnionMessenger<ES, NS, L, NL, MR, OMH, APH, CMH> where
 /// # use lightning::blinded_path::message::{BlindedMessagePath, ForwardNode, MessageContext};
 /// # use lightning::sign::{EntropySource, KeysManager};
 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
-/// # use lightning::onion_message::messenger::{Destination, MessageRouter, OnionMessagePath, OnionMessenger};
+/// # use lightning::onion_message::messenger::{BlindedPathParams, Destination, MessageRouter, OnionMessagePath, OnionMessenger};
 /// # use lightning::onion_message::packet::OnionMessageContents;
 /// # use lightning::util::logger::{Logger, Record};
 /// # use lightning::util::ser::{Writeable, Writer};
@@ -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, _recipient: PublicKey, _context: MessageContext, _peers: Vec<PublicKey>, _secp_ctx: &Secp256k1<T>
+/// #         &self, _params: BlindedPathParams, _recipient: PublicKey, _context: MessageContext, _peers: Vec<PublicKey>, _secp_ctx: &Secp256k1<T>
 /// #     ) -> Result<Vec<BlindedMessagePath>, ()> {
 /// #         unreachable!()
 /// #     }
@@ -421,7 +421,7 @@ pub struct PendingOnionMessage<T: OnionMessageContents> {
 ///
 /// PATHS_PLACEHOLDER` is temporarily used as a default value in situations
 /// where a path index is required but has not yet been assigned or initialized.
-pub const PATHS_PLACEHOLDER: usize = 0;
+pub const PATHS_PLACEHOLDER: usize = 3;
 
 /// Represents the types of [`BlindedPath`] that can be created.
 ///
@@ -461,7 +461,7 @@ pub trait MessageRouter {
 	fn create_blinded_paths<
 		T: secp256k1::Signing + secp256k1::Verification
 	>(
-		&self, recipient: PublicKey, context: MessageContext, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
+		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()>;
 
 	/// Creates compact [`BlindedMessagePath`]s to the `recipient` node. The nodes in `peers` are
@@ -487,7 +487,13 @@ pub trait MessageRouter {
 			.into_iter()
 			.map(|ForwardNode { node_id, short_channel_id: _ }| node_id)
 			.collect();
-		self.create_blinded_paths(recipient, context, peers, secp_ctx)
+
+		// This parameter is a placeholder. This function is removed in the subsequent commits.
+		let params = BlindedPathParams {
+			paths: PATHS_PLACEHOLDER,
+			is_compact: true,
+		};
+		self.create_blinded_paths(params, recipient, context, peers, secp_ctx)
 	}
 }
 
@@ -522,12 +528,9 @@ where
 		I: ExactSizeIterator<Item = ForwardNode>,
 		T: secp256k1::Signing + secp256k1::Verification
 	>(
-		network_graph: &G, recipient: PublicKey, context: MessageContext, peers: I,
-		entropy_source: &ES, secp_ctx: &Secp256k1<T>, compact_paths: bool,
+		params: BlindedPathParams, network_graph: &G, recipient: PublicKey, context: MessageContext, peers: I,
+		entropy_source: &ES, secp_ctx: &Secp256k1<T>
 	) -> Result<Vec<BlindedMessagePath>, ()> {
-		// Limit the number of blinded paths that are computed.
-		const MAX_PATHS: usize = 3;
-
 		// Ensure peers have at least three channels so that it is more difficult to infer the
 		// recipient's node_id.
 		const MIN_PEER_CHANNELS: usize = 3;
@@ -564,7 +567,7 @@ where
 			.map(|(peer, _, _)| {
 				BlindedMessagePath::new(&[peer], recipient, context.clone(), &**entropy_source, secp_ctx)
 			})
-			.take(MAX_PATHS)
+			.take(params.paths)
 			.collect::<Result<Vec<_>, _>>();
 
 		let mut paths = match paths {
@@ -579,7 +582,7 @@ where
 			},
 		}?;
 
-		if compact_paths {
+		if params.is_compact {
 			for path in &mut paths {
 				path.use_compact_introduction_node(&network_graph);
 			}
@@ -624,13 +627,13 @@ where
 	pub(crate) fn create_blinded_paths<
 		T: secp256k1::Signing + secp256k1::Verification
 	>(
-		network_graph: &G, recipient: PublicKey, context: MessageContext,
+		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| ForwardNode { node_id, short_channel_id: None });
-		Self::create_blinded_paths_from_iter(network_graph, recipient, context, peers.into_iter(), entropy_source, secp_ctx, false)
+		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<
@@ -639,7 +642,11 @@ where
 		network_graph: &G, recipient: PublicKey, context: MessageContext,
 		peers: Vec<ForwardNode>, entropy_source: &ES, secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
-		Self::create_blinded_paths_from_iter(network_graph, recipient, context, peers.into_iter(), entropy_source, secp_ctx, true)
+		let params = BlindedPathParams {
+			paths: PATHS_PLACEHOLDER,
+			is_compact: true,
+		};
+		Self::create_blinded_paths_from_iter(params, network_graph, recipient, context, peers.into_iter(), entropy_source, secp_ctx)
 	}
 }
 
@@ -657,9 +664,9 @@ where
 	fn create_blinded_paths<
 		T: secp256k1::Signing + secp256k1::Verification
 	>(
-		&self, recipient: PublicKey, context: MessageContext, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
+		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
-		Self::create_blinded_paths(&self.network_graph, recipient, context, peers, &self.entropy_source, secp_ctx)
+		Self::create_blinded_paths(params, &self.network_graph, recipient, context, peers, &self.entropy_source, secp_ctx)
 	}
 
 	fn create_compact_blinded_paths<
@@ -1235,7 +1242,7 @@ where
 			.map_err(|_| SendError::PathNotFound)
 	}
 
-	fn create_blinded_path(&self, context: MessageContext) -> Result<BlindedMessagePath, SendError> {
+	fn create_blinded_path(&self, params: BlindedPathParams, context: MessageContext) -> Result<BlindedMessagePath, SendError> {
 		let recipient = self.node_signer
 			.get_node_id(Recipient::Node)
 			.map_err(|_| SendError::GetNodeIdFailed)?;
@@ -1248,7 +1255,7 @@ where
 			.collect::<Vec<_>>();
 
 		self.message_router
-			.create_blinded_paths(recipient, context, peers, secp_ctx)
+			.create_blinded_paths(params, recipient, context, peers, secp_ctx)
 			.and_then(|paths| paths.into_iter().next().ok_or(()))
 			.map_err(|_| SendError::PathNotFound)
 	}
@@ -1346,7 +1353,11 @@ where
 
 		let message_type = response.message.msg_type();
 		let reply_path = if let Some(context) = context {
-			match self.create_blinded_path(context) {
+			let params = BlindedPathParams {
+				paths: PATHS_PLACEHOLDER,
+				is_compact: false,
+			};
+			match self.create_blinded_path(params, context) {
 				Ok(reply_path) => Some(reply_path),
 				Err(err) => {
 					log_trace!(

lightning/src/routing/router.rs

@@ -21,7 +21,7 @@ use crate::ln::features::{BlindedHopFeatures, Bolt11InvoiceFeatures, Bolt12Invoi
 use crate::ln::msgs::{DecodeError, ErrorAction, LightningError, MAX_VALUE_MSAT};
 use crate::ln::onion_utils;
 use crate::offers::invoice::{BlindedPayInfo, Bolt12Invoice};
-use crate::onion_message::messenger::{DefaultMessageRouter, Destination, MessageRouter, OnionMessagePath};
+use crate::onion_message::messenger::{BlindedPathParams, DefaultMessageRouter, Destination, MessageRouter, OnionMessagePath};
 use crate::routing::gossip::{DirectedChannelInfo, EffectiveCapacity, ReadOnlyNetworkGraph, NetworkGraph, NodeId};
 use crate::routing::scoring::{ChannelUsage, LockableScore, ScoreLookUp};
 use crate::sign::EntropySource;
@@ -196,9 +196,9 @@ impl< G: Deref<Target = NetworkGraph<L>>, L: Deref, ES: Deref, S: Deref, SP: Siz
 	fn create_blinded_paths<
 		T: secp256k1::Signing + secp256k1::Verification
 	> (
-		&self, recipient: PublicKey, context: MessageContext, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
+		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext, peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
-		DefaultMessageRouter::create_blinded_paths(&self.network_graph, recipient, context, peers, &self.entropy_source, secp_ctx)
+		DefaultMessageRouter::create_blinded_paths(params, &self.network_graph, recipient, context, peers, &self.entropy_source, secp_ctx)
 	}
 
 	fn create_compact_blinded_paths<

lightning/src/util/test_utils.rs

@@ -20,6 +20,7 @@ use crate::chain::chainmonitor;
 use crate::chain::channelmonitor;
 use crate::chain::channelmonitor::MonitorEvent;
 use crate::chain::transaction::OutPoint;
+use crate::onion_message::messenger::BlindedPathParams;
 use crate::routing::router::{CandidateRouteHop, FirstHopCandidate, PublicHopCandidate, PrivateHopCandidate};
 use crate::sign;
 use crate::events;
@@ -268,10 +269,10 @@ impl<'a> MessageRouter for TestRouter<'a> {
 	fn create_blinded_paths<
 		T: secp256k1::Signing + secp256k1::Verification
 	>(
-		&self, recipient: PublicKey, context: MessageContext,
+		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext,
 		peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
-		self.router.create_blinded_paths(recipient, context, peers, secp_ctx)
+		self.router.create_blinded_paths(params, recipient, context, peers, secp_ctx)
 	}
 
 	fn create_compact_blinded_paths<
@@ -313,10 +314,10 @@ impl<'a> MessageRouter for TestMessageRouter<'a> {
 	}
 
 	fn create_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(
-		&self, recipient: PublicKey, context: MessageContext,
+		&self, params: BlindedPathParams, recipient: PublicKey, context: MessageContext,
 		peers: Vec<PublicKey>, secp_ctx: &Secp256k1<T>,
 	) -> Result<Vec<BlindedMessagePath>, ()> {
-		self.inner.create_blinded_paths(recipient, context, peers, secp_ctx)
+		self.inner.create_blinded_paths(params, recipient, context, peers, secp_ctx)
 	}
 
 	fn create_compact_blinded_paths<T: secp256k1::Signing + secp256k1::Verification>(