f - remove fallback from ChannelManager

Author: jkczyz

lightning/src/ln/channelmanager.rs

@@ -7435,15 +7435,20 @@ where
 	/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 	pub fn create_offer_builder(
 		&self, description: String
-	) -> OfferBuilder<DerivedMetadata, secp256k1::All> {
+	) -> Result<OfferBuilder<DerivedMetadata, secp256k1::All>, Bolt12SemanticError> {
 		let node_id = self.get_our_node_id();
 		let expanded_key = &self.inbound_payment_key;
 		let entropy = &*self.entropy_source;
 		let secp_ctx = &self.secp_ctx;
 
-		OfferBuilder::deriving_signing_pubkey(description, node_id, expanded_key, entropy, secp_ctx)
+		let path = self.create_blinded_path().map_err(|_| Bolt12SemanticError::MissingPaths)?;
+		let builder = OfferBuilder::deriving_signing_pubkey(
+			description, node_id, expanded_key, entropy, secp_ctx
+		)
 			.chain_hash(self.chain_hash)
-			.path(self.create_blinded_path())
+			.path(path);
+
+		Ok(builder)
 	}
 
 	/// Creates a [`RefundBuilder`] such that the [`Refund`] it builds is recognized by the
@@ -7500,12 +7505,13 @@ where
 		let entropy = &*self.entropy_source;
 		let secp_ctx = &self.secp_ctx;
 
+		let path = self.create_blinded_path().map_err(|_| Bolt12SemanticError::MissingPaths)?;
 		let builder = RefundBuilder::deriving_payer_id(
 			description, node_id, expanded_key, entropy, secp_ctx, amount_msats, payment_id
 		)?
 			.chain_hash(self.chain_hash)
 			.absolute_expiry(absolute_expiry)
-			.path(self.create_blinded_path());
+			.path(path);
 
 		let expiration = StaleExpiration::AbsoluteTimeout(absolute_expiry);
 		self.pending_outbound_payments
@@ -7592,7 +7598,7 @@ where
 			Some(payer_note) => builder.payer_note(payer_note),
 		};
 		let invoice_request = builder.build_and_sign()?;
-		let reply_path = self.create_blinded_path();
+		let reply_path = self.create_blinded_path().map_err(|_| Bolt12SemanticError::MissingPaths)?;
 
 		let expiration = StaleExpiration::TimerTicks(1);
 		self.pending_outbound_payments
@@ -7668,7 +7674,8 @@ where
 					payment_paths, payment_hash, created_at, expanded_key, entropy
 				)?;
 				let invoice = builder.allow_mpp().build_and_sign(secp_ctx)?;
-				let reply_path = self.create_blinded_path();
+				let reply_path = self.create_blinded_path()
+					.map_err(|_| Bolt12SemanticError::MissingPaths)?;
 
 				let mut pending_offers_messages = self.pending_offers_messages.lock().unwrap();
 				if refund.paths().is_empty() {
@@ -7795,29 +7802,10 @@ where
 		inbound_payment::get_payment_preimage(payment_hash, payment_secret, &self.inbound_payment_key)
 	}
 
-	/// Creates a multi-hop blinded path by delegating to [`MessageRouter::create_blinded_paths`].
-	/// If the router returns an error or no paths, creates a one-hop blinded path instead.
-	fn create_blinded_path(&self) -> BlindedPath {
-		self.create_multi_hop_blinded_paths()
-			.ok()
-			.and_then(|paths| paths.into_iter().next())
-			.unwrap_or_else(|| self.create_one_hop_blinded_path())
-	}
-
-	/// Creates a one-hop blinded path with [`ChannelManager::get_our_node_id`] as the introduction
-	/// node.
-	fn create_one_hop_blinded_path(&self) -> BlindedPath {
-		let entropy_source = self.entropy_source.deref();
-		let secp_ctx = &self.secp_ctx;
-		BlindedPath::one_hop_for_message(self.get_our_node_id(), entropy_source, secp_ctx).unwrap()
-	}
-
-	/// Creates blinded paths by delegating to [`MessageRouter::create_blinded_paths`].
-	///
-	/// May return no paths if no peers [support onion messages].
+	/// Creates a blinded path by delegating to [`MessageRouter::create_blinded_paths`].
 	///
-	/// [support onion messages]: crate::ln::features::InitFeatures::supports_onion_messages
-	fn create_multi_hop_blinded_paths(&self) -> Result<Vec<BlindedPath>, ()> {
+	/// 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 entropy_source = self.entropy_source.deref();
 		let secp_ctx = &self.secp_ctx;
@@ -7828,7 +7816,9 @@ where
 			.map(|(node_id, _)| *node_id)
 			.collect::<Vec<_>>();
 
-		self.router.create_blinded_paths(recipient, peers, entropy_source, secp_ctx)
+		self.router
+			.create_blinded_paths(recipient, peers, entropy_source, secp_ctx)
+			.and_then(|paths| paths.into_iter().next().ok_or(()))
 	}
 
 	/// Creates a one-hop blinded payment path with [`ChannelManager::get_our_node_id`] as the