Include invreq in payment onion when sending async payments

Past commits have set us up to include invoice requests in outbound async
payment onions. Here we actually pull the invoice request from where it's
stored in outbound_payments and pass it into the correct utility for inclusion
in the onion.

Per <lightning/bolts#1149>, when paying a static
invoice we need to include our original invoice request in the HTLC onion since
the recipient wouldn't have received it previously.

Author: valentinewallace

lightning/src/ln/onion_utils.rs

@@ -320,7 +320,8 @@ pub(crate) const MIN_FINAL_VALUE_ESTIMATE_WITH_OVERPAY: u64 = 100_000_000;
 
 pub(crate) fn set_max_path_length(
 	route_params: &mut RouteParameters, recipient_onion: &RecipientOnionFields,
-	keysend_preimage: Option<PaymentPreimage>, best_block_height: u32,
+	keysend_preimage: Option<PaymentPreimage>, invoice_request: Option<&InvoiceRequest>,
+	best_block_height: u32,
 ) -> Result<(), ()> {
 	const PAYLOAD_HMAC_LEN: usize = 32;
 	let unblinded_intermed_payload_len = msgs::OutboundOnionPayload::Forward {
@@ -367,7 +368,7 @@ pub(crate) fn set_max_path_length(
 		&recipient_onion,
 		best_block_height,
 		&keysend_preimage,
-		None,
+		invoice_request,
 		|_, payload| {
 			num_reserved_bytes = num_reserved_bytes
 				.saturating_add(payload.serialized_length())

lightning/src/ln/outbound_payment.rs

@@ -951,20 +951,26 @@ impl OutboundPayments {
 			payment_hash, recipient_onion.clone(), keysend_preimage, &route, Some(retry_strategy),
 			payment_params, entropy_source, best_block_height
 		);
-		match self.pending_outbound_payments.lock().unwrap().entry(payment_id) {
-			hash_map::Entry::Occupied(entry) => match entry.get() {
-				PendingOutboundPayment::InvoiceReceived { .. }
-				| PendingOutboundPayment::StaticInvoiceReceived { .. } => {
-					*entry.into_mut() = retryable_payment;
+		let mut invoice_request_opt = None;
+		let mut outbounds = self.pending_outbound_payments.lock().unwrap();
+		match outbounds.entry(payment_id) {
+			hash_map::Entry::Occupied(entry) => match entry.remove() {
+				PendingOutboundPayment::InvoiceReceived { .. } => {
+					outbounds.insert(payment_id, retryable_payment);
+				},
+				PendingOutboundPayment::StaticInvoiceReceived { invoice_request, .. } => {
+					invoice_request_opt = Some(invoice_request);
+					outbounds.insert(payment_id, retryable_payment);
 				},
 				_ => return Err(Bolt12PaymentError::DuplicateInvoice),
 			},
 			hash_map::Entry::Vacant(_) => return Err(Bolt12PaymentError::UnexpectedInvoice),
 		}
+		core::mem::drop(outbounds);
 
 		let result = self.pay_route_internal(
-			&route, payment_hash, &recipient_onion, keysend_preimage, None, payment_id,
-			Some(route_params.final_value_msat), onion_session_privs, node_signer,
+			&route, payment_hash, &recipient_onion, keysend_preimage, invoice_request_opt.as_ref(),
+			payment_id, Some(route_params.final_value_msat), onion_session_privs, node_signer,
 			best_block_height, &send_payment_along_path
 		);
 		log_info!(
@@ -1037,7 +1043,7 @@ impl OutboundPayments {
 
 					if let Err(()) = onion_utils::set_max_path_length(
 						&mut route_params, &RecipientOnionFields::spontaneous_empty(), Some(keysend_preimage),
-						best_block_height
+						Some(invreq), best_block_height
 					) {
 						abandon_with_entry!(entry, PaymentFailureReason::RouteNotFound);
 						return Err(Bolt12PaymentError::SendingFailed(RetryableSendFailure::OnionPacketSizeExceeded))
@@ -1186,7 +1192,7 @@ impl OutboundPayments {
 		}
 
 		onion_utils::set_max_path_length(
-			route_params, recipient_onion, keysend_preimage, best_block_height
+			route_params, recipient_onion, keysend_preimage, None, best_block_height
 		)
 			.map_err(|()| {
 				log_error!(logger, "Can't construct an onion packet without exceeding 1300-byte onion \

lightning/src/routing/router.rs

@@ -641,8 +641,9 @@ impl RouteParameters {
 		&mut self, recipient_onion: &RecipientOnionFields, is_keysend: bool, best_block_height: u32
 	) -> Result<(), ()> {
 		let keysend_preimage_opt = is_keysend.then(|| PaymentPreimage([42; 32]));
+		// TODO: no way to account for the invoice request here yet
 		onion_utils::set_max_path_length(
-			self, recipient_onion, keysend_preimage_opt, best_block_height
+			self, recipient_onion, keysend_preimage_opt, None, best_block_height
 		)
 	}
 }