Add channel scoring to get_route

Failed payments may be retried, but calling get_route may return a Route
with the same failing path. Add a routing::Score trait used to
parameterize get_route, which it calls to determine how much a channel
should be penalized in terms of msats willing to pay to avoid the
channel.

Also, add a Scorer struct that implements routing::Score with a constant
constant penalty. Subsequent changes will allow for more robust scoring
by feeding back payment path success and failure to the scorer via event
handling.

Author: jkczyz

fuzz/src/full_stack.rs

@@ -37,8 +37,9 @@ use lightning::ln::channelmanager::{ChainParameters, ChannelManager};
 use lightning::ln::peer_handler::{MessageHandler,PeerManager,SocketDescriptor,IgnoringMessageHandler};
 use lightning::ln::msgs::DecodeError;
 use lightning::ln::script::ShutdownScript;
-use lightning::routing::router::get_route;
 use lightning::routing::network_graph::{NetGraphMsgHandler, NetworkGraph};
+use lightning::routing::router::get_route;
+use lightning::routing::scorer::Scorer;
 use lightning::util::config::UserConfig;
 use lightning::util::errors::APIError;
 use lightning::util::events::Event;
@@ -380,6 +381,7 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
 	let our_id = PublicKey::from_secret_key(&Secp256k1::signing_only(), &keys_manager.get_node_secret());
 	let network_graph = NetworkGraph::new(genesis_block(network).block_hash());
 	let net_graph_msg_handler = Arc::new(NetGraphMsgHandler::new(network_graph, None, Arc::clone(&logger)));
+	let scorer = Scorer::new(0);
 
 	let peers = RefCell::new([false; 256]);
 	let mut loss_detector = MoneyLossDetector::new(&peers, channelmanager.clone(), monitor.clone(), PeerManager::new(MessageHandler {
@@ -435,7 +437,7 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
 			},
 			4 => {
 				let value = slice_to_be24(get_slice!(3)) as u64;
-				let route = match get_route(&our_id, &net_graph_msg_handler.network_graph, &get_pubkey!(), None, None, &Vec::new(), value, 42, Arc::clone(&logger)) {
+				let route = match get_route(&our_id, &net_graph_msg_handler.network_graph, &get_pubkey!(), None, None, &Vec::new(), value, 42, Arc::clone(&logger), &scorer) {
 					Ok(route) => route,
 					Err(_) => return,
 				};
@@ -452,7 +454,7 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
 			},
 			15 => {
 				let value = slice_to_be24(get_slice!(3)) as u64;
-				let mut route = match get_route(&our_id, &net_graph_msg_handler.network_graph, &get_pubkey!(), None, None, &Vec::new(), value, 42, Arc::clone(&logger)) {
+				let mut route = match get_route(&our_id, &net_graph_msg_handler.network_graph, &get_pubkey!(), None, None, &Vec::new(), value, 42, Arc::clone(&logger), &scorer) {
 					Ok(route) => route,
 					Err(_) => return,
 				};

fuzz/src/router.rs

@@ -17,6 +17,7 @@ use lightning::ln::channelmanager::{ChannelDetails, ChannelCounterparty};
 use lightning::ln::features::InitFeatures;
 use lightning::ln::msgs;
 use lightning::routing::router::{get_route, RouteHint, RouteHintHop};
+use lightning::routing::scorer::Scorer;
 use lightning::util::logger::Logger;
 use lightning::util::ser::Readable;
 use lightning::routing::network_graph::{NetworkGraph, RoutingFees};
@@ -247,11 +248,12 @@ pub fn do_test<Out: test_logger::Output>(data: &[u8], out: Out) {
 						}]));
 					}
 				}
+				let scorer = Scorer::new(0);
 				for target in node_pks.iter() {
 					let _ = get_route(&our_pubkey, &net_graph, target, None,
 						first_hops.map(|c| c.iter().collect::<Vec<_>>()).as_ref().map(|a| a.as_slice()),
 						&last_hops.iter().collect::<Vec<_>>(),
-						slice_to_be64(get_slice!(8)), slice_to_be32(get_slice!(4)), Arc::clone(&logger));
+						slice_to_be64(get_slice!(8)), slice_to_be32(get_slice!(4)), Arc::clone(&logger), &scorer);
 				}
 			},
 		}

lightning-invoice/src/utils.rs

@@ -98,6 +98,7 @@ mod test {
 	use lightning::ln::features::InitFeatures;
 	use lightning::ln::msgs::ChannelMessageHandler;
 	use lightning::routing::router;
+	use lightning::routing::scorer::Scorer;
 	use lightning::util::events::MessageSendEventsProvider;
 	use lightning::util::test_utils;
 	#[test]
@@ -117,6 +118,7 @@ mod test {
 		let last_hops = invoice.route_hints();
 		let network_graph = &nodes[0].net_graph_msg_handler.network_graph;
 		let logger = test_utils::TestLogger::new();
+		let scorer = Scorer::new(0);
 		let route = router::get_route(
 			&nodes[0].node.get_our_node_id(),
 			network_graph,
@@ -127,6 +129,7 @@ mod test {
 			amt_msat,
 			invoice.min_final_cltv_expiry() as u32,
 			&logger,
+			&scorer,
 		).unwrap();
 
 		let payment_event = {

lightning/src/ln/channelmanager.rs

@@ -5804,6 +5804,7 @@ mod tests {
 	use ln::msgs;
 	use ln::msgs::ChannelMessageHandler;
 	use routing::router::{get_keysend_route, get_route};
+	use routing::scorer::Scorer;
 	use util::errors::APIError;
 	use util::events::{Event, MessageSendEvent, MessageSendEventsProvider};
 	use util::test_utils;
@@ -6042,13 +6043,14 @@ mod tests {
 		let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
 		create_announced_chan_between_nodes(&nodes, 0, 1, InitFeatures::known(), InitFeatures::known());
 		let logger = test_utils::TestLogger::new();
+		let scorer = Scorer::new(0);
 
 		// To start (1), send a regular payment but don't claim it.
 		let expected_route = [&nodes[1]];
 		let (payment_preimage, payment_hash, _) = route_payment(&nodes[0], &expected_route, 100_000);
 
 		// Next, attempt a keysend payment and make sure it fails.
-		let route = get_route(&nodes[0].node.get_our_node_id(), &nodes[0].net_graph_msg_handler.network_graph, &expected_route.last().unwrap().node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 100_000, TEST_FINAL_CLTV, &logger).unwrap();
+		let route = get_route(&nodes[0].node.get_our_node_id(), &nodes[0].net_graph_msg_handler.network_graph, &expected_route.last().unwrap().node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 100_000, TEST_FINAL_CLTV, &logger, &scorer).unwrap();
 		nodes[0].node.send_spontaneous_payment(&route, Some(payment_preimage)).unwrap();
 		check_added_monitors!(nodes[0], 1);
 		let mut events = nodes[0].node.get_and_clear_pending_msg_events();
@@ -6076,7 +6078,7 @@ mod tests {
 
 		// To start (2), send a keysend payment but don't claim it.
 		let payment_preimage = PaymentPreimage([42; 32]);
-		let route = get_route(&nodes[0].node.get_our_node_id(), &nodes[0].net_graph_msg_handler.network_graph, &expected_route.last().unwrap().node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 100_000, TEST_FINAL_CLTV, &logger).unwrap();
+		let route = get_route(&nodes[0].node.get_our_node_id(), &nodes[0].net_graph_msg_handler.network_graph, &expected_route.last().unwrap().node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 100_000, TEST_FINAL_CLTV, &logger, &scorer).unwrap();
 		let (payment_hash, _) = nodes[0].node.send_spontaneous_payment(&route, Some(payment_preimage)).unwrap();
 		check_added_monitors!(nodes[0], 1);
 		let mut events = nodes[0].node.get_and_clear_pending_msg_events();
@@ -6130,9 +6132,10 @@ mod tests {
 		let _chan = create_chan_between_nodes(&nodes[0], &nodes[1], InitFeatures::known(), InitFeatures::known());
 		let network_graph = &nodes[0].net_graph_msg_handler.network_graph;
 		let first_hops = nodes[0].node.list_usable_channels();
+		let scorer = Scorer::new(0);
 		let route = get_keysend_route(&payer_pubkey, network_graph, &payee_pubkey,
                                   Some(&first_hops.iter().collect::<Vec<_>>()), &vec![], 10000, 40,
-                                  nodes[0].logger).unwrap();
+                                  nodes[0].logger, &scorer).unwrap();
 
 		let test_preimage = PaymentPreimage([42; 32]);
 		let mismatch_payment_hash = PaymentHash([43; 32]);
@@ -6166,9 +6169,10 @@ mod tests {
 		let _chan = create_chan_between_nodes(&nodes[0], &nodes[1], InitFeatures::known(), InitFeatures::known());
 		let network_graph = &nodes[0].net_graph_msg_handler.network_graph;
 		let first_hops = nodes[0].node.list_usable_channels();
+		let scorer = Scorer::new(0);
 		let route = get_keysend_route(&payer_pubkey, network_graph, &payee_pubkey,
                                   Some(&first_hops.iter().collect::<Vec<_>>()), &vec![], 10000, 40,
-                                  nodes[0].logger).unwrap();
+                                  nodes[0].logger, &scorer).unwrap();
 
 		let test_preimage = PaymentPreimage([42; 32]);
 		let test_secret = PaymentSecret([43; 32]);
@@ -6230,6 +6234,7 @@ pub mod bench {
 	use ln::msgs::{ChannelMessageHandler, Init};
 	use routing::network_graph::NetworkGraph;
 	use routing::router::get_route;
+	use routing::scorer::Scorer;
 	use util::test_utils;
 	use util::config::UserConfig;
 	use util::events::{Event, MessageSendEvent, MessageSendEventsProvider, PaymentPurpose};
@@ -6337,8 +6342,9 @@ pub mod bench {
 		macro_rules! send_payment {
 			($node_a: expr, $node_b: expr) => {
 				let usable_channels = $node_a.list_usable_channels();
+				let scorer = Scorer::new(0);
 				let route = get_route(&$node_a.get_our_node_id(), &dummy_graph, &$node_b.get_our_node_id(), Some(InvoiceFeatures::known()),
-					Some(&usable_channels.iter().map(|r| r).collect::<Vec<_>>()), &[], 10_000, TEST_FINAL_CLTV, &logger_a).unwrap();
+					Some(&usable_channels.iter().map(|r| r).collect::<Vec<_>>()), &[], 10_000, TEST_FINAL_CLTV, &logger_a, &scorer).unwrap();
 
 				let mut payment_preimage = PaymentPreimage([0; 32]);
 				payment_preimage.0[0..8].copy_from_slice(&payment_count.to_le_bytes());

lightning/src/ln/functional_test_utils.rs

@@ -15,8 +15,9 @@ use chain::channelmonitor::ChannelMonitor;
 use chain::transaction::OutPoint;
 use ln::{PaymentPreimage, PaymentHash, PaymentSecret};
 use ln::channelmanager::{ChainParameters, ChannelManager, ChannelManagerReadArgs, RAACommitmentOrder, PaymentSendFailure};
-use routing::router::{Route, get_route};
 use routing::network_graph::{NetGraphMsgHandler, NetworkGraph};
+use routing::router::{Route, get_route};
+use routing::scorer::Scorer;
 use ln::features::{InitFeatures, InvoiceFeatures};
 use ln::msgs;
 use ln::msgs::{ChannelMessageHandler,RoutingMessageHandler};
@@ -996,11 +997,12 @@ macro_rules! get_route_and_payment_hash {
 	($send_node: expr, $recv_node: expr, $last_hops: expr, $recv_value: expr, $cltv: expr) => {{
 		let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash!($recv_node, Some($recv_value));
 		let net_graph_msg_handler = &$send_node.net_graph_msg_handler;
+		let scorer = ::routing::scorer::Scorer::new(0);
 		let route = ::routing::router::get_route(
 			&$send_node.node.get_our_node_id(), &net_graph_msg_handler.network_graph,
 			&$recv_node.node.get_our_node_id(), Some(::ln::features::InvoiceFeatures::known()),
 			Some(&$send_node.node.list_usable_channels().iter().collect::<Vec<_>>()),
-			&$last_hops, $recv_value, $cltv, $send_node.logger
+			&$last_hops, $recv_value, $cltv, $send_node.logger, &scorer
 		).unwrap();
 		(route, payment_hash, payment_preimage, payment_secret)
 	}}
@@ -1311,10 +1313,11 @@ pub const TEST_FINAL_CLTV: u32 = 70;
 
 pub fn route_payment<'a, 'b, 'c>(origin_node: &Node<'a, 'b, 'c>, expected_route: &[&Node<'a, 'b, 'c>], recv_value: u64) -> (PaymentPreimage, PaymentHash, PaymentSecret) {
 	let net_graph_msg_handler = &origin_node.net_graph_msg_handler;
+	let scorer = Scorer::new(0);
 	let route = get_route(&origin_node.node.get_our_node_id(), &net_graph_msg_handler.network_graph,
 		&expected_route.last().unwrap().node.get_our_node_id(), Some(InvoiceFeatures::known()),
 		Some(&origin_node.node.list_usable_channels().iter().collect::<Vec<_>>()), &[],
-		recv_value, TEST_FINAL_CLTV, origin_node.logger).unwrap();
+		recv_value, TEST_FINAL_CLTV, origin_node.logger, &scorer).unwrap();
 	assert_eq!(route.paths.len(), 1);
 	assert_eq!(route.paths[0].len(), expected_route.len());
 	for (node, hop) in expected_route.iter().zip(route.paths[0].iter()) {
@@ -1326,7 +1329,8 @@ pub fn route_payment<'a, 'b, 'c>(origin_node: &Node<'a, 'b, 'c>, expected_route:
 
 pub fn route_over_limit<'a, 'b, 'c>(origin_node: &Node<'a, 'b, 'c>, expected_route: &[&Node<'a, 'b, 'c>], recv_value: u64)  {
 	let net_graph_msg_handler = &origin_node.net_graph_msg_handler;
-	let route = get_route(&origin_node.node.get_our_node_id(), &net_graph_msg_handler.network_graph, &expected_route.last().unwrap().node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), recv_value, TEST_FINAL_CLTV, origin_node.logger).unwrap();
+	let scorer = Scorer::new(0);
+	let route = get_route(&origin_node.node.get_our_node_id(), &net_graph_msg_handler.network_graph, &expected_route.last().unwrap().node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), recv_value, TEST_FINAL_CLTV, origin_node.logger, &scorer).unwrap();
 	assert_eq!(route.paths.len(), 1);
 	assert_eq!(route.paths[0].len(), expected_route.len());
 	for (node, hop) in expected_route.iter().zip(route.paths[0].iter()) {

lightning/src/ln/functional_tests.rs

@@ -25,6 +25,7 @@ use ln::{chan_utils, onion_utils};
 use ln::chan_utils::HTLC_SUCCESS_TX_WEIGHT;
 use routing::network_graph::{NetworkUpdate, RoutingFees};
 use routing::router::{Route, RouteHop, RouteHint, RouteHintHop, get_route, get_keysend_route};
+use routing::scorer::Scorer;
 use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
 use ln::msgs;
 use ln::msgs::{ChannelMessageHandler, RoutingMessageHandler, ErrorAction};
@@ -7264,7 +7265,8 @@ fn test_check_htlc_underpaying() {
 	// Create some initial channels
 	create_announced_chan_between_nodes(&nodes, 0, 1, InitFeatures::known(), InitFeatures::known());
 
-	let route = get_route(&nodes[0].node.get_our_node_id(), &nodes[0].net_graph_msg_handler.network_graph, &nodes[1].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, TEST_FINAL_CLTV, nodes[0].logger).unwrap();
+	let scorer = Scorer::new(0);
+	let route = get_route(&nodes[0].node.get_our_node_id(), &nodes[0].net_graph_msg_handler.network_graph, &nodes[1].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 10_000, TEST_FINAL_CLTV, nodes[0].logger, &scorer).unwrap();
 	let (_, our_payment_hash, _) = get_payment_preimage_hash!(nodes[0]);
 	let our_payment_secret = nodes[1].node.create_inbound_payment_for_hash(our_payment_hash, Some(100_000), 7200, 0).unwrap();
 	nodes[0].node.send_payment(&route, our_payment_hash, &Some(our_payment_secret)).unwrap();
@@ -7664,11 +7666,12 @@ fn test_bump_penalty_txn_on_revoked_htlcs() {
 
 	let chan = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1000000, 59000000, InitFeatures::known(), InitFeatures::known());
 	// Lock HTLC in both directions (using a slightly lower CLTV delay to provide timely RBF bumps)
+	let scorer = Scorer::new(0);
 	let route = get_route(&nodes[0].node.get_our_node_id(), &nodes[0].net_graph_msg_handler.network_graph,
-		&nodes[1].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 3_000_000, 50, nodes[0].logger).unwrap();
+		&nodes[1].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 3_000_000, 50, nodes[0].logger, &scorer).unwrap();
 	let payment_preimage = send_along_route(&nodes[0], route, &[&nodes[1]], 3_000_000).0;
 	let route = get_route(&nodes[1].node.get_our_node_id(), &nodes[1].net_graph_msg_handler.network_graph,
-		&nodes[0].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 3_000_000, 50, nodes[0].logger).unwrap();
+		&nodes[0].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &Vec::new(), 3_000_000, 50, nodes[0].logger, &scorer).unwrap();
 	send_along_route(&nodes[1], route, &[&nodes[0]], 3_000_000);
 
 	let revoked_local_txn = get_local_commitment_txn!(nodes[1], chan.2);
@@ -9166,8 +9169,9 @@ fn test_keysend_payments_to_public_node() {
 	let network_graph = &nodes[0].net_graph_msg_handler.network_graph;
 	let payer_pubkey = nodes[0].node.get_our_node_id();
 	let payee_pubkey = nodes[1].node.get_our_node_id();
+	let scorer = Scorer::new(0);
 	let route = get_keysend_route(
-		&payer_pubkey, &network_graph, &payee_pubkey, None, &vec![], 10000, 40, nodes[0].logger
+		&payer_pubkey, &network_graph, &payee_pubkey, None, &vec![], 10000, 40, nodes[0].logger, &scorer
 	).unwrap();
 
 	let test_preimage = PaymentPreimage([42; 32]);
@@ -9196,9 +9200,10 @@ fn test_keysend_payments_to_private_node() {
 	let _chan = create_chan_between_nodes(&nodes[0], &nodes[1], InitFeatures::known(), InitFeatures::known());
 	let network_graph = &nodes[0].net_graph_msg_handler.network_graph;
 	let first_hops = nodes[0].node.list_usable_channels();
+	let scorer = Scorer::new(0);
 	let route = get_keysend_route(
 		&payer_pubkey, &network_graph, &payee_pubkey, Some(&first_hops.iter().collect::<Vec<_>>()),
-		&vec![], 10000, 40, nodes[0].logger
+		&vec![], 10000, 40, nodes[0].logger, &scorer
 	).unwrap();
 
 	let test_preimage = PaymentPreimage([42; 32]);

lightning/src/ln/shutdown_tests.rs

@@ -13,8 +13,9 @@ use chain::keysinterface::KeysInterface;
 use chain::transaction::OutPoint;
 use ln::{PaymentPreimage, PaymentHash};
 use ln::channelmanager::PaymentSendFailure;
-use routing::network_graph::NetworkUpdate;
 use routing::router::get_route;
+use routing::network_graph::NetworkUpdate;
+use routing::scorer::Scorer;
 use ln::features::{InitFeatures, InvoiceFeatures};
 use ln::msgs;
 use ln::msgs::{ChannelMessageHandler, ErrorAction};
@@ -81,6 +82,7 @@ fn updates_shutdown_wait() {
 	let chan_1 = create_announced_chan_between_nodes(&nodes, 0, 1, InitFeatures::known(), InitFeatures::known());
 	let chan_2 = create_announced_chan_between_nodes(&nodes, 1, 2, InitFeatures::known(), InitFeatures::known());
 	let logger = test_utils::TestLogger::new();
+	let scorer = Scorer::new(0);
 
 	let (our_payment_preimage, our_payment_hash, _) = route_payment(&nodes[0], &[&nodes[1], &nodes[2]], 100000);
 
@@ -97,8 +99,8 @@ fn updates_shutdown_wait() {
 
 	let net_graph_msg_handler0 = &nodes[0].net_graph_msg_handler;
 	let net_graph_msg_handler1 = &nodes[1].net_graph_msg_handler;
-	let route_1 = get_route(&nodes[0].node.get_our_node_id(), &net_graph_msg_handler0.network_graph, &nodes[1].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &[], 100000, TEST_FINAL_CLTV, &logger).unwrap();
-	let route_2 = get_route(&nodes[1].node.get_our_node_id(), &net_graph_msg_handler1.network_graph, &nodes[0].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &[], 100000, TEST_FINAL_CLTV, &logger).unwrap();
+	let route_1 = get_route(&nodes[0].node.get_our_node_id(), &net_graph_msg_handler0.network_graph, &nodes[1].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &[], 100000, TEST_FINAL_CLTV, &logger, &scorer).unwrap();
+	let route_2 = get_route(&nodes[1].node.get_our_node_id(), &net_graph_msg_handler1.network_graph, &nodes[0].node.get_our_node_id(), Some(InvoiceFeatures::known()), None, &[], 100000, TEST_FINAL_CLTV, &logger, &scorer).unwrap();
 	unwrap_send_err!(nodes[0].node.send_payment(&route_1, payment_hash, &Some(payment_secret)), true, APIError::ChannelUnavailable {..}, {});
 	unwrap_send_err!(nodes[1].node.send_payment(&route_2, payment_hash, &Some(payment_secret)), true, APIError::ChannelUnavailable {..}, {});
 

lightning/src/routing/mod.rs

@@ -9,5 +9,14 @@
 
 //! Structs and impls for receiving messages about the network and storing the topology live here.
 
-pub mod router;
 pub mod network_graph;
+pub mod router;
+pub mod scorer;
+
+/// An interface used to score payment channels for path finding.
+///
+///	Scoring is in terms of fees willing to be paid in order to avoid routing through a channel.
+pub trait Score {
+	/// Returns the fee in msats willing to be paid to avoid routing through the given channel.
+	fn channel_penalty_msat(&self, short_channel_id: u64) -> u64;
+}