Add some checks on provided payment details

As per spec, we check that the user provides at least one payment detail
*and* that they don't provide onchain payment details if
`refund_onchain_address` is unset.

Author: tnull

lightning-liquidity/src/lsps1/service.rs

@@ -357,6 +357,23 @@ where
 						let created_at = LSPSDateTime::new_from_duration_since_epoch(
 							self.time_provider.duration_since_epoch(),
 						);
+
+						if payment_details.bolt11.is_none()
+							&& payment_details.bolt12.is_none()
+							&& payment_details.onchain.is_none()
+						{
+							let err = format!("At least one payment option must be provided");
+							return Err(APIError::APIMisuseError { err });
+						}
+
+						if params.refund_onchain_address.is_none()
+							&& payment_details.onchain.is_some()
+						{
+							// bLIP-51: 'LSP MUST disable on-chain payments if the client omits this field.'
+							let err = format!("Onchain payments must be disabled if no refund_onchain_address is set.");
+							return Err(APIError::APIMisuseError { err });
+						}
+
 						let order = peer_state_lock.new_order(
 							order_id.clone(),
 							params.order,

lightning-liquidity/tests/lsps1_integration_tests.rs

@@ -145,8 +145,15 @@ fn lsps1_happy_path() {
 		announce_channel: true,
 	};
 
-	let _create_order_id =
-		client_handler.create_order(&service_node_id, order_params.clone(), None);
+	let refund_onchain_address =
+		Address::from_str("bc1p5uvtaxzkjwvey2tfy49k5vtqfpjmrgm09cvs88ezyy8h2zv7jhas9tu4yr")
+			.unwrap()
+			.assume_checked();
+	let _create_order_id = client_handler.create_order(
+		&service_node_id,
+		order_params.clone(),
+		Some(refund_onchain_address),
+	);
 	let create_order = get_lsps_message!(client_node, service_node_id);
 
 	service_node.liquidity_manager.handle_custom_message(create_order, client_node_id).unwrap();