#[derive(Clone, Hash, PartialEq, Eq)]
pub struct Route {
/// The list of routes taken for a single (potentially-)multi-part payment. The pubkey of the
- /// last RouteHop in each path must be the same.
- /// Each entry represents a list of hops, NOT INCLUDING our own, where the last hop is the
- /// destination. Thus, this must always be at least length one. While the maximum length of any
- /// given path is variable, keeping the length of any path to less than 20 should currently
- /// ensure it is viable.
+ /// last RouteHop in each path must be the same. Each entry represents a list of hops, NOT
+ /// INCLUDING our own, where the last hop is the destination. Thus, this must always be at
+ /// least length one. While the maximum length of any given path is variable, keeping the length
+ /// of any path less or equal to 19 should currently ensure it is viable.
pub paths: Vec<Vec<RouteHop>>,
/// The `payment_params` parameter passed to [`find_route`].
/// This is used by `ChannelManager` to track information which may be required for retries,
/// Maximum total CTLV difference we allow for a full payment path.
pub const DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA: u32 = 1008;
-/// The median hop CLTV expiry delta currently seen in the network.
+// The median hop CLTV expiry delta currently seen in the network.
const MEDIAN_HOP_CLTV_EXPIRY_DELTA: u32 = 40;
+// During routing, we only consider paths shorter than our maximum length estimate.
+// In the legacy onion format, the maximum number of hops used to be a fixed value of 20.
+// However, in the TLV onion format, there is no fixed maximum length, but the `hop_payloads`
+// field is always 1300 bytes. As the `tlv_payload` for each hop may vary in length, we have to
+// estimate how many hops the route may have so that it actually fits the `hop_payloads` field.
+//
+// We estimate 3+32 (payload length and HMAC) + 2+8 (amt_to_forward) + 2+4 (outgoing_cltv_value) +
+// 2+8 (short_channel_id) = 61 bytes for each intermediate hop and 3+32
+// (payload length and HMAC) + 2+8 (amt_to_forward) + 2+4 (outgoing_cltv_value) + 2+32+8
+// (payment_secret and total_msat) = 93 bytes for the final hop.
+// Since the length of the potentially included `payment_metadata` is unknown to us, we round
+// down from (1300-93) / 61 = 19.78... to arrive at a conservative estimate of 19.
+const MAX_PATH_LENGTH_ESTIMATE: u8 = 19;
+
/// The recipient of a payment.
#[derive(Clone, Debug, Hash, PartialEq, Eq)]
pub struct PaymentParameters {
/// All penalties incurred from this hop on the way to the destination, as calculated using
/// channel scoring.
path_penalty_msat: u64,
+ /// The number of hops walked up to this node.
+ path_length_to_node: u8,
}
impl cmp::Ord for RouteGraphNode {
// The main heap containing all candidate next-hops sorted by their score (max(A* fee,
// htlc_minimum)). Ideally this would be a heap which allowed cheap score reduction instead of
// adding duplicate entries when we find a better path to a given node.
- let mut targets = BinaryHeap::new();
+ let mut targets: BinaryHeap<RouteGraphNode> = BinaryHeap::new();
// Map from node_id to information about the best current path to that node, including feerate
// information.
- let mut dist = HashMap::with_capacity(network_nodes.len());
+ let mut dist: HashMap<NodeId, PathBuildingHop> = HashMap::with_capacity(network_nodes.len());
// During routing, if we ignore a path due to an htlc_minimum_msat limit, we set this,
// indicating that we may wish to try again with a higher value, potentially paying to meet an
// since that value has to be transferred over this channel.
// Returns whether this channel caused an update to `targets`.
( $candidate: expr, $src_node_id: expr, $dest_node_id: expr, $next_hops_fee_msat: expr,
- $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr,
- $next_hops_path_penalty_msat: expr, $next_hops_cltv_delta: expr ) => { {
+ $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr,
+ $next_hops_path_penalty_msat: expr, $next_hops_cltv_delta: expr, $next_hops_path_length: expr ) => { {
// We "return" whether we updated the path at the end, via this:
let mut did_add_update_path_to_src_node = false;
// Channels to self should not be used. This is more of belt-and-suspenders, because in
};
// Verify the liquidity offered by this channel complies to the minimal contribution.
let contributes_sufficient_value = available_value_contribution_msat >= minimal_value_contribution_msat;
+ // Do not consider candidate hops that would exceed the maximum path length.
+ let path_length_to_node = $next_hops_path_length + 1;
+ let doesnt_exceed_max_path_length = path_length_to_node <= MAX_PATH_LENGTH_ESTIMATE;
// Do not consider candidates that exceed the maximum total cltv expiry limit.
// In order to already account for some of the privacy enhancing random CLTV
// bother considering this channel. If retrying with recommended_value_msat may
// allow us to hit the HTLC minimum limit, set htlc_minimum_limit so that we go
// around again with a higher amount.
- if contributes_sufficient_value && doesnt_exceed_cltv_delta_limit && may_overpay_to_meet_path_minimum_msat {
+ if contributes_sufficient_value && doesnt_exceed_max_path_length &&
+ doesnt_exceed_cltv_delta_limit && may_overpay_to_meet_path_minimum_msat {
hit_minimum_limit = true;
- } else if contributes_sufficient_value && doesnt_exceed_cltv_delta_limit && over_path_minimum_msat {
+ } else if contributes_sufficient_value && doesnt_exceed_max_path_length &&
+ doesnt_exceed_cltv_delta_limit && over_path_minimum_msat {
// Note that low contribution here (limited by available_liquidity_msat)
// might violate htlc_minimum_msat on the hops which are next along the
// payment path (upstream to the payee). To avoid that, we recompute
value_contribution_msat: value_contribution_msat,
path_htlc_minimum_msat,
path_penalty_msat,
+ path_length_to_node,
};
// Update the way of reaching $src_node_id with the given short_channel_id (from $dest_node_id),
// meaning how much will be paid in fees after this node (to the best of our knowledge).
// This data can later be helpful to optimize routing (pay lower fees).
macro_rules! add_entries_to_cheapest_to_target_node {
- ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr, $next_hops_path_htlc_minimum_msat: expr, $next_hops_path_penalty_msat: expr, $next_hops_cltv_delta: expr ) => {
+ ( $node: expr, $node_id: expr, $fee_to_target_msat: expr, $next_hops_value_contribution: expr,
+ $next_hops_path_htlc_minimum_msat: expr, $next_hops_path_penalty_msat: expr,
+ $next_hops_cltv_delta: expr, $next_hops_path_length: expr ) => {
let skip_node = if let Some(elem) = dist.get_mut(&$node_id) {
let was_processed = elem.was_processed;
elem.was_processed = true;
if let Some(first_channels) = first_hop_targets.get(&$node_id) {
for details in first_channels {
let candidate = CandidateRouteHop::FirstHop { details };
- add_entry!(candidate, our_node_id, $node_id, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat, $next_hops_cltv_delta);
+ add_entry!(candidate, our_node_id, $node_id, $fee_to_target_msat,
+ $next_hops_value_contribution,
+ $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat,
+ $next_hops_cltv_delta, $next_hops_path_length);
}
}
info: directed_channel.with_update().unwrap(),
short_channel_id: *chan_id,
};
- add_entry!(candidate, *source, $node_id, $fee_to_target_msat, $next_hops_value_contribution, $next_hops_path_htlc_minimum_msat, $next_hops_path_penalty_msat, $next_hops_cltv_delta);
+ add_entry!(candidate, *source, $node_id,
+ $fee_to_target_msat,
+ $next_hops_value_contribution,
+ $next_hops_path_htlc_minimum_msat,
+ $next_hops_path_penalty_msat,
+ $next_hops_cltv_delta, $next_hops_path_length);
}
}
}
if let Some(first_channels) = first_hop_targets.get(&payee_node_id) {
for details in first_channels {
let candidate = CandidateRouteHop::FirstHop { details };
- let added = add_entry!(candidate, our_node_id, payee_node_id, 0, path_value_msat, 0, 0u64, 0);
- log_trace!(logger, "{} direct route to payee via SCID {}", if added { "Added" } else { "Skipped" }, candidate.short_channel_id());
+ let added = add_entry!(candidate, our_node_id, payee_node_id, 0, path_value_msat,
+ 0, 0u64, 0, 0);
+ log_trace!(logger, "{} direct route to payee via SCID {}",
+ if added { "Added" } else { "Skipped" }, candidate.short_channel_id());
}
}
// If not, targets.pop() will not even let us enter the loop in step 2.
None => {},
Some(node) => {
- add_entries_to_cheapest_to_target_node!(node, payee_node_id, 0, path_value_msat, 0, 0u64, 0);
+ add_entries_to_cheapest_to_target_node!(node, payee_node_id, 0, path_value_msat, 0, 0u64, 0, 0);
},
}
let mut aggregate_next_hops_path_htlc_minimum_msat: u64 = 0;
let mut aggregate_next_hops_path_penalty_msat: u64 = 0;
let mut aggregate_next_hops_cltv_delta: u32 = 0;
+ let mut aggregate_next_hops_path_length: u8 = 0;
for (idx, (hop, prev_hop_id)) in hop_iter.zip(prev_hop_iter).enumerate() {
let source = NodeId::from_pubkey(&hop.src_node_id);
.unwrap_or_else(|| CandidateRouteHop::PrivateHop { hint: hop });
let capacity_msat = candidate.effective_capacity().as_msat();
aggregate_next_hops_path_penalty_msat = aggregate_next_hops_path_penalty_msat
- .saturating_add(scorer.channel_penalty_msat(hop.short_channel_id, final_value_msat, capacity_msat, &source, &target));
+ .saturating_add(scorer.channel_penalty_msat(hop.short_channel_id,
+ final_value_msat, capacity_msat, &source, &target));
aggregate_next_hops_cltv_delta = aggregate_next_hops_cltv_delta
.saturating_add(hop.cltv_expiry_delta as u32);
- if !add_entry!(candidate, source, target, aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta) {
- // If this hop was not used then there is no use checking the preceding hops
- // in the RouteHint. We can break by just searching for a direct channel between
- // last checked hop and first_hop_targets
+ aggregate_next_hops_path_length = aggregate_next_hops_path_length
+ .saturating_add(1);
+
+ if !add_entry!(candidate, source, target, aggregate_next_hops_fee_msat,
+ path_value_msat, aggregate_next_hops_path_htlc_minimum_msat,
+ aggregate_next_hops_path_penalty_msat,
+ aggregate_next_hops_cltv_delta, aggregate_next_hops_path_length) {
+ // If this hop was not used then there is no use checking the preceding
+ // hops in the RouteHint. We can break by just searching for a direct
+ // channel between last checked hop and first_hop_targets.
hop_used = false;
}
if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&prev_hop_id)) {
for details in first_channels {
let candidate = CandidateRouteHop::FirstHop { details };
- add_entry!(candidate, our_node_id, NodeId::from_pubkey(&prev_hop_id), aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta);
+ add_entry!(candidate, our_node_id, NodeId::from_pubkey(&prev_hop_id),
+ aggregate_next_hops_fee_msat, path_value_msat,
+ aggregate_next_hops_path_htlc_minimum_msat,
+ aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta,
+ aggregate_next_hops_path_length);
}
}
// In the next values of the iterator, the aggregate fees already reflects
// the sum of value sent from payer (final_value_msat) and routing fees
// for the last node in the RouteHint. We need to just add the fees to
- // route through the current node so that the preceeding node (next iteration)
+ // route through the current node so that the preceding node (next iteration)
// can use it.
let hops_fee = compute_fees(aggregate_next_hops_fee_msat + final_value_msat, hop.fees)
.map_or(None, |inc| inc.checked_add(aggregate_next_hops_fee_msat));
if let Some(first_channels) = first_hop_targets.get(&NodeId::from_pubkey(&hop.src_node_id)) {
for details in first_channels {
let candidate = CandidateRouteHop::FirstHop { details };
- add_entry!(candidate, our_node_id, NodeId::from_pubkey(&hop.src_node_id), aggregate_next_hops_fee_msat, path_value_msat, aggregate_next_hops_path_htlc_minimum_msat, aggregate_next_hops_path_penalty_msat, aggregate_next_hops_cltv_delta);
+ add_entry!(candidate, our_node_id,
+ NodeId::from_pubkey(&hop.src_node_id),
+ aggregate_next_hops_fee_msat, path_value_msat,
+ aggregate_next_hops_path_htlc_minimum_msat,
+ aggregate_next_hops_path_penalty_msat,
+ aggregate_next_hops_cltv_delta,
+ aggregate_next_hops_path_length);
}
}
}
// 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, .. }) = targets.pop() {
+ '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() {
// 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.
if node_id == our_node_id {
let mut new_entry = dist.remove(&our_node_id).unwrap();
- let mut ordered_hops = vec!((new_entry.clone(), default_node_features.clone()));
+ let mut ordered_hops: Vec<(PathBuildingHop, NodeFeatures)> = vec!((new_entry.clone(), default_node_features.clone()));
'path_walk: loop {
let mut features_set = false;
match network_nodes.get(&node_id) {
None => {},
Some(node) => {
- add_entries_to_cheapest_to_target_node!(node, node_id, lowest_fee_to_node, value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat, total_cltv_delta);
+ add_entries_to_cheapest_to_target_node!(node, node_id, lowest_fee_to_node,
+ value_contribution_msat, path_htlc_minimum_msat, path_penalty_msat,
+ total_cltv_delta, path_length_to_node);
},
}
}
#[cfg(test)]
mod tests {
use routing::network_graph::{NetworkGraph, NetGraphMsgHandler, NodeId};
- use routing::router::{get_route, add_random_cltv_offset, default_node_features, PaymentParameters, Route, RouteHint, RouteHintHop, RouteHop, RoutingFees, DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA};
+ use routing::router::{get_route, add_random_cltv_offset, default_node_features,
+ PaymentParameters, Route, RouteHint, RouteHintHop, RouteHop, RoutingFees,
+ DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA, MAX_PATH_LENGTH_ESTIMATE};
use routing::scoring::Score;
use chain::transaction::OutPoint;
use chain::keysinterface::KeysInterface;
use ln::features::{ChannelFeatures, InitFeatures, InvoiceFeatures, NodeFeatures};
use ln::msgs::{ErrorAction, LightningError, OptionalField, UnsignedChannelAnnouncement, ChannelAnnouncement, RoutingMessageHandler,
- NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
+ NodeAnnouncement, UnsignedNodeAnnouncement, ChannelUpdate, UnsignedChannelUpdate};
use ln::channelmanager;
use util::test_utils;
use util::chacha20::ChaCha20;
}
fn get_nodes(secp_ctx: &Secp256k1<All>) -> (SecretKey, PublicKey, Vec<SecretKey>, Vec<PublicKey>) {
- let privkeys: Vec<SecretKey> = (2..10).map(|i| {
+ let privkeys: Vec<SecretKey> = (2..22).map(|i| {
SecretKey::from_slice(&hex::decode(format!("{:02x}", i).repeat(32)).unwrap()[..]).unwrap()
}).collect();
}
}
+ fn build_line_graph() -> (
+ Secp256k1<All>, sync::Arc<NetworkGraph>, NetGraphMsgHandler<sync::Arc<NetworkGraph>,
+ sync::Arc<test_utils::TestChainSource>, sync::Arc<crate::util::test_utils::TestLogger>>,
+ sync::Arc<test_utils::TestChainSource>, sync::Arc<test_utils::TestLogger>,
+ ) {
+ let secp_ctx = Secp256k1::new();
+ let logger = Arc::new(test_utils::TestLogger::new());
+ let chain_monitor = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
+ let network_graph = Arc::new(NetworkGraph::new(genesis_block(Network::Testnet).header.block_hash()));
+ let net_graph_msg_handler = NetGraphMsgHandler::new(Arc::clone(&network_graph), None, Arc::clone(&logger));
+
+ // Build network from our_id to node 19:
+ // our_id -1(1)2- node0 -1(2)2- node1 - ... - node19
+ let (our_privkey, _, privkeys, _) = get_nodes(&secp_ctx);
+
+ for (idx, (cur_privkey, next_privkey)) in core::iter::once(&our_privkey)
+ .chain(privkeys.iter()).zip(privkeys.iter()).enumerate() {
+ let cur_short_channel_id = (idx as u64) + 1;
+ add_channel(&net_graph_msg_handler, &secp_ctx, &cur_privkey, &next_privkey,
+ ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), cur_short_channel_id);
+ update_channel(&net_graph_msg_handler, &secp_ctx, &cur_privkey, UnsignedChannelUpdate {
+ chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ short_channel_id: cur_short_channel_id,
+ timestamp: idx as u32,
+ flags: 0,
+ cltv_expiry_delta: 0,
+ htlc_minimum_msat: 0,
+ htlc_maximum_msat: OptionalField::Absent,
+ fee_base_msat: 0,
+ fee_proportional_millionths: 0,
+ excess_data: Vec::new()
+ });
+ update_channel(&net_graph_msg_handler, &secp_ctx, &next_privkey, UnsignedChannelUpdate {
+ chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ short_channel_id: cur_short_channel_id,
+ timestamp: (idx as u32)+1,
+ flags: 1,
+ cltv_expiry_delta: 0,
+ htlc_minimum_msat: 0,
+ htlc_maximum_msat: OptionalField::Absent,
+ fee_base_msat: 0,
+ fee_proportional_millionths: 0,
+ excess_data: Vec::new()
+ });
+ add_or_update_node(&net_graph_msg_handler, &secp_ctx, next_privkey,
+ NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
+ }
+
+ (secp_ctx, network_graph, net_graph_msg_handler, chain_monitor, logger)
+ }
+
fn build_graph() -> (
Secp256k1<All>,
sync::Arc<NetworkGraph>,
}
}
+ #[test]
+ fn limits_path_length() {
+ let (secp_ctx, network, _, _, logger) = build_line_graph();
+ let (_, our_id, _, nodes) = get_nodes(&secp_ctx);
+ let network_graph = network.read_only();
+
+ let scorer = test_utils::TestScorer::with_penalty(0);
+ let keys_manager = test_utils::TestKeysInterface::new(&[0u8; 32], Network::Testnet);
+ let random_seed_bytes = keys_manager.get_secure_random_bytes();
+
+ // First check we can actually create a long route on this graph.
+ let feasible_payment_params = PaymentParameters::from_node_id(nodes[18]);
+ let route = get_route(&our_id, &feasible_payment_params, &network_graph, None, 100, 0,
+ Arc::clone(&logger), &scorer, &random_seed_bytes).unwrap();
+ let path = route.paths[0].iter().map(|hop| hop.short_channel_id).collect::<Vec<_>>();
+ assert!(path.len() == MAX_PATH_LENGTH_ESTIMATE.into());
+
+ // But we can't create a path surpassing the MAX_PATH_LENGTH_ESTIMATE limit.
+ let fail_payment_params = PaymentParameters::from_node_id(nodes[19]);
+ match get_route(&our_id, &fail_payment_params, &network_graph, None, 100, 0,
+ Arc::clone(&logger), &scorer, &random_seed_bytes)
+ {
+ Err(LightningError { err, .. } ) => {
+ assert_eq!(err, "Failed to find a path to the given destination");
+ },
+ Ok(_) => panic!("Expected error"),
+ }
+ }
+
#[test]
fn adds_and_limits_cltv_offset() {
let (secp_ctx, network_graph, _, _, logger) = build_graph();
projects / rust-lightning / commitdiff