Remove now-unused ServeStaticInvoice::invoice_id

In the initially-merged version of the static invoice server protocol, the
static invoice server would sometimes have to find a specific static invoice
based on (recipient_id, invoice_slot) and sometimetimes based on (recipient_id,
invoice_id). This made the API harder to use in terms of how the server would
index into the KVStore.

Over the course of the previous commits we transitioned to the server always
finding a specific invoice based on (recipient_id, invoice_slot). We still have
a few dangling references to invoice_id in some messages and events though, so
remove those here.

Author: valentinewallace

lightning/src/blinded_path/message.rs

@@ -474,7 +474,7 @@ pub enum AsyncPaymentsContext {
 		/// An identifier for the async recipient that is requesting that a [`StaticInvoice`] be served
 		/// on their behalf.
 		///
-		/// Useful when surfaced alongside the below `invoice_id` when payers send an
+		/// Useful when surfaced alongside the below `invoice_slot` when payers send an
 		/// [`InvoiceRequest`], to pull the specific static invoice from the database.
 		///
 		/// Also useful to rate limit the invoices being persisted on behalf of a particular recipient.
@@ -485,13 +485,6 @@ pub enum AsyncPaymentsContext {
 		/// [`StaticInvoice`]: crate::offers::static_invoice::StaticInvoice
 		/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 		recipient_id: Vec<u8>,
-		/// A random identifier for the specific [`StaticInvoice`] that the recipient is requesting be
-		/// served on their behalf. Useful when surfaced alongside the above `recipient_id` when payers
-		/// send an [`InvoiceRequest`], to pull the specific static invoice from the database.
-		///
-		/// [`StaticInvoice`]: crate::offers::static_invoice::StaticInvoice
-		/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
-		invoice_id: u128,
 		/// The slot number for the specific [`StaticInvoice`] that the recipient is requesting be
 		/// served on their behalf. Useful when surfaced alongside the above `recipient_id` when payers
 		/// send an [`InvoiceRequest`], to pull the specific static invoice from the database. This id
@@ -600,9 +593,8 @@ impl_writeable_tlv_based_enum!(AsyncPaymentsContext,
 	},
 	(5, ServeStaticInvoice) => {
 		(0, recipient_id, required),
-		(2, invoice_id, required),
+		(2, invoice_slot, required),
 		(4, path_absolute_expiry, required),
-		(6, invoice_slot, required),
 	},
 );
 

lightning/src/events/mod.rs

@@ -1661,18 +1661,11 @@ pub enum Event {
 		/// [`ChannelManager::blinded_paths_for_async_recipient`].
 		///
 		/// When an [`Event::StaticInvoiceRequested`] comes in for the invoice, this id will be surfaced
-		/// and can be used alongside the `invoice_id` to retrieve the invoice from the database.
+		/// and can be used alongside the `invoice_slot` to retrieve the invoice from the database.
 		///
 		///[`ChannelManager::blinded_paths_for_async_recipient`]: crate::ln::channelmanager::ChannelManager::blinded_paths_for_async_recipient
 		recipient_id: Vec<u8>,
-		/// A random identifier for the invoice. When an [`Event::StaticInvoiceRequested`] comes in for
-		/// the invoice, this id will be surfaced and can be used alongside the `recipient_id` to
-		/// retrieve the invoice from the database.
-		///
-		/// Note that this id will remain the same for all invoice updates corresponding to a particular
-		/// offer that the recipient has cached.
-		invoice_id: u128,
-		/// Once the [`StaticInvoice`], `invoice_slot` and `invoice_id` are persisted,
+		/// Once the [`StaticInvoice`] and `invoice_slot` are persisted,
 		/// [`ChannelManager::static_invoice_persisted`] should be called with this responder to confirm
 		/// to the recipient that their [`Offer`] is ready to be used for async payments.
 		///

lightning/src/ln/async_payments_tests.rs

@@ -66,7 +66,6 @@ use core::time::Duration;
 struct StaticInvoiceServerFlowResult {
 	invoice: StaticInvoice,
 	invoice_slot: u16,
-	invoice_id: u128,
 
 	// Returning messages that were sent along the way allows us to test handling duplicate messages.
 	offer_paths_request: msgs::OnionMessage,
@@ -148,16 +147,15 @@ fn pass_static_invoice_server_messages(
 	// that the static invoice should be persisted.
 	let mut events = server.node.get_and_clear_pending_events();
 	assert_eq!(events.len(), 1);
-	let (invoice, invoice_slot, invoice_id, ack_path) = match events.pop().unwrap() {
+	let (invoice, invoice_slot, ack_path) = match events.pop().unwrap() {
 		Event::PersistStaticInvoice {
 			invoice,
 			invoice_persisted_path,
 			recipient_id: ev_id,
 			invoice_slot,
-			invoice_id,
 		} => {
 			assert_eq!(recipient_id, ev_id);
-			(invoice, invoice_slot, invoice_id, invoice_persisted_path)
+			(invoice, invoice_slot, invoice_persisted_path)
 		},
 		_ => panic!(),
 	};
@@ -183,7 +181,6 @@ fn pass_static_invoice_server_messages(
 		static_invoice_persisted_message: invoice_persisted_om,
 		invoice,
 		invoice_slot,
-		invoice_id,
 	}
 }
 
@@ -1626,13 +1623,13 @@ fn limit_serve_static_invoice_requests() {
 
 	// Build the target number of offers interactively with the static invoice server.
 	let mut offer_paths_req = None;
-	let mut invoice_ids = new_hash_set();
+	let mut invoice_slots = new_hash_set();
 	for expected_inv_slot in 0..TEST_MAX_CACHED_OFFERS_TARGET {
 		let flow_res = pass_static_invoice_server_messages(server, recipient, recipient_id.clone());
 		assert_eq!(flow_res.invoice_slot, expected_inv_slot as u16);
 
 		offer_paths_req = Some(flow_res.offer_paths_request);
-		invoice_ids.insert(flow_res.invoice_id);
+		invoice_slots.insert(flow_res.invoice_slot);
 
 		// Trigger a cache refresh
 		recipient.node.timer_tick_occurred();
@@ -1641,8 +1638,8 @@ fn limit_serve_static_invoice_requests() {
 		recipient.node.flow.test_get_async_receive_offers().len(),
 		TEST_MAX_CACHED_OFFERS_TARGET
 	);
-	// Check that all invoice ids are unique.
-	assert_eq!(invoice_ids.len(), TEST_MAX_CACHED_OFFERS_TARGET);
+	// Check that all invoice slot numbers are unique.
+	assert_eq!(invoice_slots.len(), TEST_MAX_CACHED_OFFERS_TARGET);
 
 	// Force allowing more offer paths request attempts so we can check that the recipient will not
 	// attempt to build any further offers.
@@ -1822,16 +1819,15 @@ fn refresh_static_invoices_for_used_offers() {
 		Event::PersistStaticInvoice {
 			invoice,
 			invoice_slot,
-			invoice_id,
 			invoice_persisted_path,
 			recipient_id: ev_id,
 		} => {
 			assert_ne!(original_invoice, invoice);
 			assert_eq!(recipient_id, ev_id);
 			assert_eq!(invoice_slot, flow_res.invoice_slot);
-			// When we update the invoice corresponding to a specific offer, the invoice_id stays the
+			// When we update the invoice corresponding to a specific offer, the invoice_slot stays the
 			// same.
-			assert_eq!(invoice_id, flow_res.invoice_id);
+			assert_eq!(invoice_slot, flow_res.invoice_slot);
 			(invoice, invoice_persisted_path)
 		},
 		_ => panic!(),

lightning/src/ln/channelmanager.rs

@@ -14445,9 +14445,8 @@ where
 		responder: Option<Responder>,
 	) -> Option<(OfferPaths, ResponseInstruction)> {
 		let peers = self.get_peers_for_blinded_path();
-		let entropy = &*self.entropy_source;
 		let (message, reply_path_context) =
-			match self.flow.handle_offer_paths_request(&message, context, peers, entropy) {
+			match self.flow.handle_offer_paths_request(&message, context, peers) {
 				Some(msg) => msg,
 				None => return None,
 			};
@@ -14490,9 +14489,9 @@ where
 			None => return,
 		};
 
-		let (recipient_id, invoice_slot, invoice_id) =
+		let (recipient_id, invoice_slot) =
 			match self.flow.verify_serve_static_invoice_message(&message, context) {
-				Ok((recipient_id, inv_slot, inv_id)) => (recipient_id, inv_slot, inv_id),
+				Ok((recipient_id, inv_slot)) => (recipient_id, inv_slot),
 				Err(()) => return,
 			};
 
@@ -14502,7 +14501,6 @@ where
 				invoice: message.invoice,
 				invoice_slot,
 				recipient_id,
-				invoice_id,
 				invoice_persisted_path: responder,
 			},
 			None,

lightning/src/offers/flow.rs

@@ -1371,13 +1371,10 @@ where
 	/// Handles an incoming [`OfferPathsRequest`] onion message from an often-offline recipient who
 	/// wants us (the static invoice server) to serve [`StaticInvoice`]s to payers on their behalf.
 	/// Sends out [`OfferPaths`] onion messages in response.
-	pub fn handle_offer_paths_request<ES: Deref>(
+	pub fn handle_offer_paths_request(
 		&self, request: &OfferPathsRequest, context: AsyncPaymentsContext,
-		peers: Vec<MessageForwardNode>, entropy_source: ES,
-	) -> Option<(OfferPaths, MessageContext)>
-	where
-		ES::Target: EntropySource,
-	{
+		peers: Vec<MessageForwardNode>,
+	) -> Option<(OfferPaths, MessageContext)> {
 		let duration_since_epoch = self.duration_since_epoch();
 
 		let recipient_id = match context {
@@ -1390,10 +1387,6 @@ where
 			_ => return None,
 		};
 
-		let mut random_bytes = [0u8; 16];
-		random_bytes.copy_from_slice(&entropy_source.get_secure_random_bytes()[..16]);
-		let invoice_id = u128::from_be_bytes(random_bytes);
-
 		// Create the blinded paths that will be included in the async recipient's offer.
 		let (offer_paths, paths_expiry) = {
 			let path_absolute_expiry =
@@ -1418,7 +1411,6 @@ where
 				duration_since_epoch.saturating_add(DEFAULT_ASYNC_RECEIVE_OFFER_EXPIRY);
 			MessageContext::AsyncPayments(AsyncPaymentsContext::ServeStaticInvoice {
 				recipient_id,
-				invoice_id,
 				invoice_slot: request.invoice_slot,
 				path_absolute_expiry,
 			})
@@ -1577,7 +1569,7 @@ where
 	/// wants us as a static invoice server to serve the [`ServeStaticInvoice::invoice`] to payers on
 	/// their behalf.
 	///
-	/// On success, returns `(recipient_id, invoice_id)` for use in persisting and later retrieving
+	/// On success, returns `(recipient_id, invoice_slot)` for use in persisting and later retrieving
 	/// the static invoice from the database.
 	///
 	/// Errors if the [`ServeStaticInvoice::invoice`] is expired or larger than
@@ -1586,7 +1578,7 @@ where
 	/// [`ServeStaticInvoice::invoice`]: crate::onion_message::async_payments::ServeStaticInvoice::invoice
 	pub fn verify_serve_static_invoice_message(
 		&self, message: &ServeStaticInvoice, context: AsyncPaymentsContext,
-	) -> Result<(Vec<u8>, u16, u128), ()> {
+	) -> Result<(Vec<u8>, u16), ()> {
 		if message.invoice.is_expired_no_std(self.duration_since_epoch()) {
 			return Err(());
 		}
@@ -1596,15 +1588,14 @@ where
 		match context {
 			AsyncPaymentsContext::ServeStaticInvoice {
 				recipient_id,
-				invoice_id,
 				invoice_slot,
 				path_absolute_expiry,
 			} => {
 				if self.duration_since_epoch() > path_absolute_expiry {
 					return Err(());
 				}
 
-				return Ok((recipient_id, invoice_slot, invoice_id));
+				return Ok((recipient_id, invoice_slot));
 			},
 			_ => return Err(()),
 		};