Static invoice server

fuzz/src/onion_message.rs

@@ -15,7 +15,8 @@ use lightning::ln::peer_handler::IgnoringMessageHandler;
 use lightning::ln::script::ShutdownScript;
 use lightning::offers::invoice::UnsignedBolt12Invoice;
 use lightning::onion_message::async_payments::{
-	AsyncPaymentsMessageHandler, HeldHtlcAvailable, ReleaseHeldHtlc,
+	AsyncPaymentsMessageHandler, HeldHtlcAvailable, OfferPaths, OfferPathsRequest, ReleaseHeldHtlc,
+	ServeStaticInvoice, StaticInvoicePersisted,
 };
 use lightning::onion_message::messenger::{
 	CustomOnionMessageHandler, Destination, MessageRouter, MessageSendInstructions,
@@ -124,6 +125,30 @@ impl OffersMessageHandler for TestOffersMessageHandler {
 struct TestAsyncPaymentsMessageHandler {}
 
 impl AsyncPaymentsMessageHandler for TestAsyncPaymentsMessageHandler {
+	fn handle_offer_paths_request(
+		&self, _message: OfferPathsRequest, _context: AsyncPaymentsContext,
+		responder: Option<Responder>,
+	) -> Option<(OfferPaths, ResponseInstruction)> {
+		let responder = match responder {
+			Some(resp) => resp,
+			None => return None,
+		};
+		Some((OfferPaths { paths: Vec::new(), paths_absolute_expiry: None }, responder.respond()))
+	}
+	fn handle_offer_paths(
+		&self, _message: OfferPaths, _context: AsyncPaymentsContext, _responder: Option<Responder>,
+	) -> Option<(ServeStaticInvoice, ResponseInstruction)> {
+		None
+	}
+	fn handle_serve_static_invoice(
+		&self, _message: ServeStaticInvoice, _context: AsyncPaymentsContext,
+		_responder: Option<Responder>,
+	) {
+	}
+	fn handle_static_invoice_persisted(
+		&self, _message: StaticInvoicePersisted, _context: AsyncPaymentsContext,
+	) {
+	}
 	fn handle_held_htlc_available(
 		&self, _message: HeldHtlcAvailable, _context: AsyncPaymentsContext,
 		responder: Option<Responder>,

lightning/src/blinded_path/message.rs

@@ -23,6 +23,8 @@ use crate::ln::channelmanager::PaymentId;
 use crate::ln::msgs::DecodeError;
 use crate::ln::onion_utils;
 use crate::offers::nonce::Nonce;
+use crate::offers::offer::Offer;
+use crate::onion_message::messenger::Responder;
 use crate::onion_message::packet::ControlTlvs;
 use crate::routing::gossip::{NodeId, ReadOnlyNetworkGraph};
 use crate::sign::{EntropySource, NodeSigner, Recipient};
@@ -34,6 +36,7 @@ use bitcoin::hashes::sha256::Hash as Sha256;
 
 use core::mem;
 use core::ops::Deref;
+use core::time::Duration;
 
 /// A blinded path to be used for sending or receiving a message, hiding the identity of the
 /// recipient.
@@ -341,6 +344,47 @@ pub enum OffersContext {
 		/// [`Offer`]: crate::offers::offer::Offer
 		nonce: Nonce,
 	},
+	/// Context used by a [`BlindedMessagePath`] within the [`Offer`] of an async recipient.
+	///
+	/// This variant is received by the static invoice server when handling an [`InvoiceRequest`] on
+	/// behalf of said async recipient.
+	///
+	/// [`StaticInvoice`]: crate::offers::static_invoice::StaticInvoice
+	/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+	StaticInvoiceRequested {
+		/// An identifier for the async recipient for whom the static invoice server is serving
+		/// [`StaticInvoice`]s. Used to look up a corresponding [`StaticInvoice`] to return to the payer
+		/// if the recipient is offline.
+		///
+		/// Also useful for the server to rate limit the number of [`InvoiceRequest`]s it will respond
+		/// to on recipient's behalf.
+		///
+		/// [`StaticInvoice`]: crate::offers::static_invoice::StaticInvoice
+		/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+		recipient_id_nonce: Nonce,
+
+		/// A nonce used for authenticating that a received [`InvoiceRequest`] is valid for a preceding
+		/// [`OfferPaths`] message sent by the static invoice server.
+		///
+		/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+		/// [`OfferPaths`]: crate::onion_message::async_payments::OfferPaths
+		nonce: Nonce,
+
+		/// Authentication code for the [`InvoiceRequest`].
+		///
+		/// Prevents nodes from creating their own blinded path to the static invoice server and causing
+		/// them to unintentionally hit their database looking for a [`StaticInvoice`] to return.
+		///
+		/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+		/// [`StaticInvoice`]: crate::offers::static_invoice::StaticInvoice
+		hmac: Hmac<Sha256>,
+
+		/// The time as duration since the Unix epoch at which this path expires and messages sent over
+		/// it should be ignored.
+		///
+		/// Useful to timeout async recipients that are no longer supported as clients.
+		path_absolute_expiry: Duration,
+	},
 	/// Context used by a [`BlindedMessagePath`] within a [`Refund`] or as a reply path for an
 	/// [`InvoiceRequest`].
 	///
@@ -404,6 +448,148 @@ pub enum OffersContext {
 /// [`AsyncPaymentsMessage`]: crate::onion_message::async_payments::AsyncPaymentsMessage
 #[derive(Clone, Debug)]
 pub enum AsyncPaymentsContext {
+	/// Context used by a [`BlindedMessagePath`] that an async recipient is configured with in
+	/// [`UserConfig::paths_to_static_invoice_server`], provided back to the static invoice server in
+	/// corresponding [`OfferPathsRequest`]s.
+	///
+	/// [`UserConfig::paths_to_static_invoice_server`]: crate::util::config::UserConfig::paths_to_static_invoice_server
+	/// [`OfferPathsRequest`]: crate::onion_message::async_payments::OfferPathsRequest
+	OfferPathsRequest {
+		/// An identifier for the async recipient that is requesting blinded paths to include in their
+		/// [`Offer::paths`]. This ID will be surfaced when the async recipient eventually sends a
+		/// corresponding [`ServeStaticInvoice`] message, and can be used to rate limit the recipient.
+		///
+		/// [`Offer::paths`]: crate::offers::offer::Offer::paths
+		/// [`ServeStaticInvoice`]: crate::onion_message::async_payments::ServeStaticInvoice
+		recipient_id_nonce: Nonce,
+		/// Authentication code for the [`OfferPathsRequest`].
+		///
+		/// Prevents nodes from requesting offer paths from the static invoice server without having
+		/// been previously configured with a [`BlindedMessagePath`] that the server generated.
+		///
+		/// [`OfferPathsRequest`]: crate::onion_message::async_payments::OfferPathsRequest
+		hmac: Hmac<Sha256>,
+		/// The time as duration since the Unix epoch at which this path expires and messages sent over
+		/// it should be ignored.
+		///
+		/// Useful to timeout async recipients that are no longer supported as clients.
+		path_absolute_expiry: core::time::Duration,
+	},
+	/// Context used by a reply path to an [`OfferPathsRequest`], provided back to us in corresponding
+	/// [`OfferPaths`] messages.
+	///
+	/// [`OfferPathsRequest`]: crate::onion_message::async_payments::OfferPathsRequest
+	/// [`OfferPaths`]: crate::onion_message::async_payments::OfferPaths
+	OfferPaths {
+		/// A nonce used for authenticating that an [`OfferPaths`] message is valid for a preceding
+		/// [`OfferPathsRequest`].
+		///
+		/// [`OfferPathsRequest`]: crate::onion_message::async_payments::OfferPathsRequest
+		/// [`OfferPaths`]: crate::onion_message::async_payments::OfferPaths
+		nonce: Nonce,
+		/// Authentication code for the [`OfferPaths`] message.
+		///
+		/// Prevents nodes from creating their own blinded path to us and causing us to cache an
+		/// unintended async receive offer.
+		///
+		/// [`OfferPaths`]: crate::onion_message::async_payments::OfferPaths
+		hmac: Hmac<Sha256>,
+		/// The time as duration since the Unix epoch at which this path expires and messages sent over
+		/// it should be ignored.
+		///
+		/// Used to time out a static invoice server from providing offer paths if the async recipient
+		/// is no longer configured to accept paths from them.
+		path_absolute_expiry: core::time::Duration,
+	},
+	/// Context used by a reply path to an [`OfferPaths`] message, provided back to the static invoice
+	/// server in corresponding [`ServeStaticInvoice`] messages.
+	///
+	/// [`OfferPaths`]: crate::onion_message::async_payments::OfferPaths
+	/// [`ServeStaticInvoice`]: crate::onion_message::async_payments::ServeStaticInvoice
+	ServeStaticInvoice {
+		/// An identifier for the async recipient that is requesting that a [`StaticInvoice`] be served
+		/// on their behalf.
+		///
+		/// Useful as a key to retrieve the invoice when payers send an [`InvoiceRequest`] to the static
+		/// invoice server. Also useful to rate limit the invoices being persisted on behalf of a
+		/// particular recipient.
+		///
+		/// [`StaticInvoice`]: crate::offers::static_invoice::StaticInvoice
+		/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+		/// [`Offer::paths`]: crate::offers::offer::Offer::paths
+		recipient_id_nonce: Nonce,
+		/// A nonce used for authenticating that a [`ServeStaticInvoice`] message is valid for a preceding
+		/// [`OfferPaths`] message.
+		///
+		/// [`ServeStaticInvoice`]: crate::onion_message::async_payments::ServeStaticInvoice
+		/// [`OfferPaths`]: crate::onion_message::async_payments::OfferPaths
+		nonce: Nonce,
+		/// Authentication code for the [`ServeStaticInvoice`] message.
+		///
+		/// Prevents nodes from creating their own blinded path to the static invoice server and causing
+		/// them to persist an unintended [`StaticInvoice`].
+		///
+		/// [`ServeStaticInvoice`]: crate::onion_message::async_payments::ServeStaticInvoice
+		/// [`StaticInvoice`]: crate::offers::static_invoice::StaticInvoice
+		hmac: Hmac<Sha256>,
+		/// The time as duration since the Unix epoch at which this path expires and messages sent over
+		/// it should be ignored.
+		///
+		/// Useful to timeout async recipients that are no longer supported as clients.
+		path_absolute_expiry: core::time::Duration,
+	},
+	/// Context used by a reply path to a [`ServeStaticInvoice`] message, provided back to us in
+	/// corresponding [`StaticInvoicePersisted`] messages.
+	///
+	/// [`ServeStaticInvoice`]: crate::onion_message::async_payments::ServeStaticInvoice
+	/// [`StaticInvoicePersisted`]: crate::onion_message::async_payments::StaticInvoicePersisted
+	StaticInvoicePersisted {
+		/// The offer corresponding to the [`StaticInvoice`] that has been persisted. This invoice is
+		/// now ready to be provided by the static invoice server in response to [`InvoiceRequest`]s.
+		///
+		/// [`StaticInvoice`]: crate::offers::static_invoice::StaticInvoice
+		/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+		offer: Offer,
+		/// A [`Nonce`] useful for updating the [`StaticInvoice`] that corresponds to the
+		/// [`AsyncPaymentsContext::StaticInvoicePersisted::offer`], since the offer may be much longer
+		/// lived than the invoice.
+		///
+		/// [`StaticInvoice`]: crate::offers::static_invoice::StaticInvoice
+		offer_nonce: Nonce,
+		/// Useful to determine how far an offer is into its lifespan, to decide whether the offer is
+		/// expiring soon and we should start building a new one.
+		offer_created_at: core::time::Duration,
+		/// A [`Responder`] useful for updating the [`StaticInvoice`] that corresponds to the
+		/// [`AsyncPaymentsContext::StaticInvoicePersisted::offer`], since the offer may be much longer
+		/// lived than the invoice.
+		///
+		/// [`StaticInvoice`]: crate::offers::static_invoice::StaticInvoice
+		update_static_invoice_path: Responder,
+		/// The time as duration since the Unix epoch at which the [`StaticInvoice`] expires, used to track
+		/// when we need to generate and persist a new invoice with the static invoice server.
+		///
+		/// [`StaticInvoice`]: crate::offers::static_invoice::StaticInvoice
+		static_invoice_absolute_expiry: core::time::Duration,
+		/// A nonce used for authenticating that a [`StaticInvoicePersisted`] message is valid for a
+		/// preceding [`ServeStaticInvoice`] message.
+		///
+		/// [`StaticInvoicePersisted`]: crate::onion_message::async_payments::StaticInvoicePersisted
+		/// [`ServeStaticInvoice`]: crate::onion_message::async_payments::ServeStaticInvoice
+		nonce: Nonce,
+		/// Authentication code for the [`StaticInvoicePersisted`] message.
+		///
+		/// Prevents nodes from creating their own blinded path to us and causing us to cache an
+		/// unintended async receive offer.
+		///
+		/// [`StaticInvoicePersisted`]: crate::onion_message::async_payments::StaticInvoicePersisted
+		hmac: Hmac<Sha256>,
+		/// The time as duration since the Unix epoch at which this path expires and messages sent over
+		/// it should be ignored.
+		///
+		/// Prevents a static invoice server from causing an async recipient to cache an old offer if
+		/// the recipient is no longer configured to use that server.
+		path_absolute_expiry: core::time::Duration,
+	},
 	/// Context contained within the reply [`BlindedMessagePath`] we put in outbound
 	/// [`HeldHtlcAvailable`] messages, provided back to us in corresponding [`ReleaseHeldHtlc`]
 	/// messages.
@@ -473,6 +659,12 @@ impl_writeable_tlv_based_enum!(OffersContext,
 		(1, nonce, required),
 		(2, hmac, required)
 	},
+	(3, StaticInvoiceRequested) => {
+		(0, recipient_id_nonce, required),
+		(2, nonce, required),
+		(4, hmac, required),
+		(6, path_absolute_expiry, required),
+	},
 );
 
 impl_writeable_tlv_based_enum!(AsyncPaymentsContext,
@@ -486,6 +678,32 @@ impl_writeable_tlv_based_enum!(AsyncPaymentsContext,
 		(2, hmac, required),
 		(4, path_absolute_expiry, required),
 	},
+	(2, OfferPaths) => {
+		(0, nonce, required),
+		(2, hmac, required),
+		(4, path_absolute_expiry, required),
+	},
+	(3, StaticInvoicePersisted) => {
+		(0, offer, required),
+		(2, offer_nonce, required),
+		(4, offer_created_at, required),
+		(6, update_static_invoice_path, required),
+		(8, static_invoice_absolute_expiry, required),
+		(10, nonce, required),
+		(12, hmac, required),
+		(14, path_absolute_expiry, required),
+	},
+	(4, OfferPathsRequest) => {
+		(0, recipient_id_nonce, required),
+		(2, hmac, required),
+		(4, path_absolute_expiry, required),
+	},
+	(5, ServeStaticInvoice) => {
+		(0, recipient_id_nonce, required),
+		(2, nonce, required),
+		(4, hmac, required),
+		(6, path_absolute_expiry, required),
+	},
 );
 
 /// Contains a simple nonce for use in a blinded path's context.