diff --git a/lightning/src/ln/functional_tests.rs b/lightning/src/ln/functional_tests.rs index 4894ed02b3b..1da45bf2c99 100644 --- a/lightning/src/ln/functional_tests.rs +++ b/lightning/src/ln/functional_tests.rs @@ -1059,26 +1059,6 @@ fn fake_network_test() { fail_payment(&nodes[1], &vec!(&nodes[3], &nodes[2], &nodes[1])[..], payment_hash_2); claim_payment(&nodes[1], &vec!(&nodes[2], &nodes[3], &nodes[1])[..], payment_preimage_1); - // Add a duplicate new channel from 2 to 4 - let chan_5 = create_announced_chan_between_nodes(&nodes, 1, 3, InitFeatures::known(), InitFeatures::known()); - - // Send some payments across both channels - let payment_preimage_3 = route_payment(&nodes[0], &vec!(&nodes[1], &nodes[3])[..], 3000000).0; - let payment_preimage_4 = route_payment(&nodes[0], &vec!(&nodes[1], &nodes[3])[..], 3000000).0; - let payment_preimage_5 = route_payment(&nodes[0], &vec!(&nodes[1], &nodes[3])[..], 3000000).0; - - - route_over_limit(&nodes[0], &vec!(&nodes[1], &nodes[3])[..], 3000000); - let events = nodes[0].node.get_and_clear_pending_msg_events(); - assert_eq!(events.len(), 0); - nodes[0].logger.assert_log_regex("lightning::ln::channelmanager".to_string(), regex::Regex::new(r"Cannot send value that would put us over the max HTLC value in flight our peer will accept \(\d+\)").unwrap(), 1); - - //TODO: Test that routes work again here as we've been notified that the channel is full - - claim_payment(&nodes[0], &vec!(&nodes[1], &nodes[3])[..], payment_preimage_3); - claim_payment(&nodes[0], &vec!(&nodes[1], &nodes[3])[..], payment_preimage_4); - claim_payment(&nodes[0], &vec!(&nodes[1], &nodes[3])[..], payment_preimage_5); - // Close down the channels... close_channel(&nodes[0], &nodes[1], &chan_1.2, chan_1.3, true); check_closed_event!(nodes[0], 1, ClosureReason::CooperativeClosure); @@ -1092,9 +1072,6 @@ fn fake_network_test() { close_channel(&nodes[1], &nodes[3], &chan_4.2, chan_4.3, false); check_closed_event!(nodes[1], 1, ClosureReason::CooperativeClosure); check_closed_event!(nodes[3], 1, ClosureReason::CooperativeClosure); - close_channel(&nodes[1], &nodes[3], &chan_5.2, chan_5.3, false); - check_closed_event!(nodes[1], 1, ClosureReason::CooperativeClosure); - check_closed_event!(nodes[3], 1, ClosureReason::CooperativeClosure); } #[test] diff --git a/lightning/src/routing/router.rs b/lightning/src/routing/router.rs index a97e1b6ffa4..1b14e9c735f 100644 --- a/lightning/src/routing/router.rs +++ b/lightning/src/routing/router.rs @@ -238,7 +238,7 @@ pub struct PaymentParameters { /// A value of 0 will allow payments up to and including a channel's total announced usable /// capacity, a value of one will only use up to half its capacity, two 1/4, etc. /// - /// Default value: 1 + /// Default value: 2 pub max_channel_saturation_power_of_half: u8, /// A list of SCIDs which this payment was previously attempted over and which caused the @@ -253,7 +253,7 @@ impl_writeable_tlv_based!(PaymentParameters, { (2, features, option), (3, max_path_count, (default_value, DEFAULT_MAX_PATH_COUNT)), (4, route_hints, vec_type), - (5, max_channel_saturation_power_of_half, (default_value, 1)), + (5, max_channel_saturation_power_of_half, (default_value, 2)), (6, expiry_time, option), (7, previously_failed_channels, vec_type), }); @@ -268,7 +268,7 @@ impl PaymentParameters { expiry_time: None, max_total_cltv_expiry_delta: DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA, max_path_count: DEFAULT_MAX_PATH_COUNT, - max_channel_saturation_power_of_half: 1, + max_channel_saturation_power_of_half: 2, previously_failed_channels: Vec::new(), } } @@ -754,7 +754,7 @@ where L::Target: Logger, GL::Target: Logger { pub(crate) fn get_route( our_node_pubkey: &PublicKey, payment_params: &PaymentParameters, network_graph: &ReadOnlyNetworkGraph, first_hops: Option<&[&ChannelDetails]>, final_value_msat: u64, final_cltv_expiry_delta: u32, - logger: L, scorer: &S, random_seed_bytes: &[u8; 32] + logger: L, scorer: &S, _random_seed_bytes: &[u8; 32] ) -> Result where L::Target: Logger { let payee_node_id = NodeId::from_pubkey(&payment_params.payee_pubkey); @@ -796,11 +796,11 @@ where L::Target: Logger { // 4. See if we managed to collect paths which aggregately are able to transfer target value // (not recommended value). // 5. If yes, proceed. If not, fail routing. - // 6. Randomly combine paths into routes having enough to fulfill the payment. (TODO: knapsack) - // 7. Of all the found paths, select only those with the lowest total fee. - // 8. The last path in every selected route is likely to be more than we need. - // Reduce its value-to-transfer and recompute fees. - // 9. Choose the best route by the lowest total fee. + // 6. Select the paths which have the lowest cost (fee plus scorer penalty) per amount + // transferred up to the transfer target value. + // 7. Reduce the value of the last path until we are sending only the target value. + // 8. If our maximum channel saturation limit caused us to pick two identical paths, combine + // them so that we're not sending two HTLCs along the same path. // As for the actual search algorithm, // we do a payee-to-payer pseudo-Dijkstra's sorting by each node's distance from the payee @@ -1476,7 +1476,7 @@ where L::Target: Logger { // Both these cases (and other cases except reaching recommended_value_msat) mean that // paths_collection will be stopped because found_new_path==false. // This is not necessarily a routing failure. - 'path_construction: while let Some(RouteGraphNode { node_id, lowest_fee_to_node, total_cltv_delta, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat, path_length_to_node, .. }) = targets.pop() { + 'path_construction: while let Some(RouteGraphNode { node_id, lowest_fee_to_node, total_cltv_delta, mut value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat, path_length_to_node, .. }) = targets.pop() { // Since we're going payee-to-payer, hitting our node as a target means we should stop // traversing the graph and arrange the path out of what we found. @@ -1542,7 +1542,9 @@ where L::Target: Logger { // on some channels we already passed (assuming dest->source direction). Here, we // recompute the fees again, so that if that's the case, we match the currently // underpaid htlc_minimum_msat with fees. - payment_path.update_value_and_recompute_fees(cmp::min(value_contribution_msat, final_value_msat)); + debug_assert_eq!(payment_path.get_value_msat(), value_contribution_msat); + value_contribution_msat = cmp::min(value_contribution_msat, final_value_msat); + payment_path.update_value_and_recompute_fees(value_contribution_msat); // Since a path allows to transfer as much value as // the smallest channel it has ("bottleneck"), we should recompute @@ -1653,96 +1655,55 @@ where L::Target: Logger { return Err(LightningError{err: "Failed to find a sufficient route to the given destination".to_owned(), action: ErrorAction::IgnoreError}); } - // Sort by total fees and take the best paths. - payment_paths.sort_unstable_by_key(|path| path.get_total_fee_paid_msat()); - if payment_paths.len() > 50 { - payment_paths.truncate(50); - } + // Step (6). + let mut selected_route = payment_paths; - // Draw multiple sufficient routes by randomly combining the selected paths. - let mut drawn_routes = Vec::new(); - let mut prng = ChaCha20::new(random_seed_bytes, &[0u8; 12]); - let mut random_index_bytes = [0u8; ::core::mem::size_of::()]; + debug_assert_eq!(selected_route.iter().map(|p| p.get_value_msat()).sum::(), already_collected_value_msat); + let mut overpaid_value_msat = already_collected_value_msat - final_value_msat; - let num_permutations = payment_paths.len(); - for _ in 0..num_permutations { - let mut cur_route = Vec::::new(); - let mut aggregate_route_value_msat = 0; + // First, sort by the cost-per-value of the path, dropping the paths that cost the most for + // the value they contribute towards the payment amount. + // We sort in descending order as we will remove from the front in `retain`, next. + selected_route.sort_unstable_by(|a, b| + (((b.get_cost_msat() as u128) << 64) / (b.get_value_msat() as u128)) + .cmp(&(((a.get_cost_msat() as u128) << 64) / (a.get_value_msat() as u128))) + ); - // Step (6). - // Do a Fisher-Yates shuffle to create a random permutation of the payment paths - for cur_index in (1..payment_paths.len()).rev() { - prng.process_in_place(&mut random_index_bytes); - let random_index = usize::from_be_bytes(random_index_bytes).wrapping_rem(cur_index+1); - payment_paths.swap(cur_index, random_index); + // We should make sure that at least 1 path left. + let mut paths_left = selected_route.len(); + selected_route.retain(|path| { + if paths_left == 1 { + return true + } + let path_value_msat = path.get_value_msat(); + if path_value_msat <= overpaid_value_msat { + overpaid_value_msat -= path_value_msat; + paths_left -= 1; + return false; } + true + }); + debug_assert!(selected_route.len() > 0); + if overpaid_value_msat != 0 { // Step (7). - for payment_path in &payment_paths { - cur_route.push(payment_path.clone()); - aggregate_route_value_msat += payment_path.get_value_msat(); - if aggregate_route_value_msat > final_value_msat { - // Last path likely overpaid. Substract it from the most expensive - // (in terms of proportional fee) path in this route and recompute fees. - // This might be not the most economically efficient way, but fewer paths - // also makes routing more reliable. - let mut overpaid_value_msat = aggregate_route_value_msat - final_value_msat; - - // First, we drop some expensive low-value paths entirely if possible, since fewer - // paths is better: the payment is less likely to fail. In order to do so, we sort - // by value and fall back to total fees paid, i.e., in case of equal values we - // prefer lower cost paths. - cur_route.sort_unstable_by(|a, b| { - a.get_value_msat().cmp(&b.get_value_msat()) - // Reverse ordering for cost, so we drop higher-cost paths first - .then_with(|| b.get_cost_msat().cmp(&a.get_cost_msat())) - }); - - // We should make sure that at least 1 path left. - let mut paths_left = cur_route.len(); - cur_route.retain(|path| { - if paths_left == 1 { - return true - } - let mut keep = true; - let path_value_msat = path.get_value_msat(); - if path_value_msat <= overpaid_value_msat { - keep = false; - overpaid_value_msat -= path_value_msat; - paths_left -= 1; - } - keep - }); - - if overpaid_value_msat == 0 { - break; - } + // Now, subtract the remaining overpaid value from the most-expensive path. + // TODO: this could also be optimized by also sorting by feerate_per_sat_routed, + // so that the sender pays less fees overall. And also htlc_minimum_msat. + selected_route.sort_unstable_by(|a, b| { + let a_f = a.hops.iter().map(|hop| hop.0.candidate.fees().proportional_millionths as u64).sum::(); + let b_f = b.hops.iter().map(|hop| hop.0.candidate.fees().proportional_millionths as u64).sum::(); + a_f.cmp(&b_f).then_with(|| b.get_cost_msat().cmp(&a.get_cost_msat())) + }); + let expensive_payment_path = selected_route.first_mut().unwrap(); - assert!(cur_route.len() > 0); - - // Step (8). - // Now, subtract the overpaid value from the most-expensive path. - // TODO: this could also be optimized by also sorting by feerate_per_sat_routed, - // so that the sender pays less fees overall. And also htlc_minimum_msat. - cur_route.sort_unstable_by_key(|path| { path.hops.iter().map(|hop| hop.0.candidate.fees().proportional_millionths as u64).sum::() }); - let expensive_payment_path = cur_route.first_mut().unwrap(); - - // We already dropped all the small value paths above, meaning all the - // remaining paths are larger than remaining overpaid_value_msat. - // Thus, this can't be negative. - let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat; - expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat); - break; - } - } - drawn_routes.push(cur_route); + // We already dropped all the paths with value below `overpaid_value_msat` above, thus this + // can't go negative. + let expensive_path_new_value_msat = expensive_payment_path.get_value_msat() - overpaid_value_msat; + expensive_payment_path.update_value_and_recompute_fees(expensive_path_new_value_msat); } - // Step (9). - // Select the best route by lowest total cost. - drawn_routes.sort_unstable_by_key(|paths| paths.iter().map(|path| path.get_cost_msat()).sum::()); - let selected_route = drawn_routes.first_mut().unwrap(); - + // Step (8). // Sort by the path itself and combine redundant paths. // Note that we sort by SCIDs alone as its simpler but when combining we have to ensure we // compare both SCIDs and NodeIds as individual nodes may use random aliases causing collisions @@ -4796,7 +4757,7 @@ mod tests { cltv_expiry_delta: 42, htlc_minimum_msat: None, htlc_maximum_msat: None, - }])]); + }])]).with_max_channel_saturation_power_of_half(0); // Keep only two paths from us to nodes[2], both with a 99sat HTLC maximum, with one with // no fee and one with a 1msat fee. Previously, trying to route 100 sats to nodes[2] here @@ -5780,7 +5741,7 @@ mod tests { flags: 0, cltv_expiry_delta: (4 << 4) | 1, htlc_minimum_msat: 0, - htlc_maximum_msat: OptionalField::Present(200_000_000), + htlc_maximum_msat: OptionalField::Present(250_000_000), fee_base_msat: 0, fee_proportional_millionths: 0, excess_data: Vec::new() @@ -5792,7 +5753,7 @@ mod tests { flags: 0, cltv_expiry_delta: (13 << 4) | 1, htlc_minimum_msat: 0, - htlc_maximum_msat: OptionalField::Present(200_000_000), + htlc_maximum_msat: OptionalField::Present(250_000_000), fee_base_msat: 0, fee_proportional_millionths: 0, excess_data: Vec::new() @@ -5801,8 +5762,8 @@ mod tests { let payment_params = PaymentParameters::from_node_id(nodes[2]).with_features(InvoiceFeatures::known()); let keys_manager = test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet); let random_seed_bytes = keys_manager.get_secure_random_bytes(); - // 150,000 sat is less than the available liquidity on each channel, set above. - let route = get_route(&our_id, &payment_params, &network_graph.read_only(), None, 150_000_000, 42, Arc::clone(&logger), &scorer, &random_seed_bytes).unwrap(); + // 100,000 sats is less than the available liquidity on each channel, set above. + let route = get_route(&our_id, &payment_params, &network_graph.read_only(), None, 100_000_000, 42, Arc::clone(&logger), &scorer, &random_seed_bytes).unwrap(); assert_eq!(route.paths.len(), 2); assert!((route.paths[0][1].short_channel_id == 4 && route.paths[1][1].short_channel_id == 13) || (route.paths[1][1].short_channel_id == 4 && route.paths[0][1].short_channel_id == 13));