From 79fe67619b105f05669521c715bab3a17c8c4b9f Mon Sep 17 00:00:00 2001 From: ziggie Date: Sat, 29 Nov 2025 00:10:17 +0100 Subject: [PATCH] routerrpc: implement LSP heuristic and multi-LSP worst-case probing MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This commit implements a comprehensive LSP (Lightning Service Provider) detection heuristic and updates the payment probing logic to handle multiple LSPs with worst-case fee estimation. Key changes: 1. LSP Detection Heuristic (isLSP function): Implements three rules to detect LSP setups: - Rule 1: If invoice target is public → NOT an LSP (route directly) - Rule 2: If at least one destination hop is public → IS an LSP - Rule 3: If all destination hops are private → NOT an LSP 2. LSP Route Preparation (prepareLspRouteHints function): - Groups route hints by unique public LSP nodes - Filters out non-LSP routes based on the heuristic - Tracks worst-case fees and CLTV delays for each LSP - Returns adjusted route hints with LSP hop stripped 3. Multi-LSP Probing (probePaymentRequest updates): - Probes up to 3 unique LSPs maximum (griefing protection) - Selects the WORST-CASE (most expensive) route for conservative fee estimation - Adds comprehensive debug logging for worst-case selection process - Properly formats vertex logging using %v (calls Vertex.String()) The worst-case approach ensures users won't be surprised by higher fees when the actual payment is sent, providing a more conservative and reliable fee estimate. This commit also adds extensive unit test coverage for the LSP detection heuristic and route preparation logic. TestIsLsp: - Edge cases: empty route hints, nil scenarios - Rule 1: Public invoice target (3 tests) - Rule 2: All private destination hops (4 tests) - Rule 3: At least one public destination hop (6 tests) TestPrepareLspRouteHints: - LSP grouping and filtering logic - Worst-case fee selection across route hints - Worst-case CLTV delta tracking - Adjusted route hints validation (LSP hop stripped) - Multi-LSP scenarios with different fees --- lnrpc/routerrpc/router_server.go | 461 ++++++++++++------ lnrpc/routerrpc/router_server_test.go | 663 +++++++++++++++++++------- 2 files changed, 790 insertions(+), 334 deletions(-) diff --git a/lnrpc/routerrpc/router_server.go b/lnrpc/routerrpc/router_server.go index 1dbc19e47..db04526d4 100644 --- a/lnrpc/routerrpc/router_server.go +++ b/lnrpc/routerrpc/router_server.go @@ -1,7 +1,6 @@ package routerrpc import ( - "bytes" "context" crand "crypto/rand" "errors" @@ -44,6 +43,12 @@ const ( // DefaultPaymentTimeout is the default value of time we should spend // when attempting to fulfill the payment. DefaultPaymentTimeout int32 = 60 + + // MaxLspsToProbe is the maximum number of LSPs to probe when + // estimating fees for worst-case fee estimation. This is a + // precautionary measure to prevent the estimation from taking too + // long, and it is also a griefing protection. + MaxLspsToProbe = 3 ) var ( @@ -171,10 +176,9 @@ var ( DefaultRouterMacFilename = "router.macaroon" ) -// FetchChannelEndpoints returns the pubkeys of both endpoints of the -// given channel id if it exists in the graph. -type FetchChannelEndpoints func(chanID uint64) (route.Vertex, route.Vertex, - error) +// HasNode returns true if the node exists in the graph (i.e., has public +// channels), false otherwise. +type HasNode func(nodePub route.Vertex) (bool, error) // ServerShell is a shell struct holding a reference to the actual sub-server. // It is used to register the gRPC sub-server with the root server before we @@ -561,7 +565,8 @@ func (s *Server) probePaymentRequest(ctx context.Context, paymentRequest string, // If the hints don't indicate an LSP then chances are that our probe // payment won't be blocked along the route to the destination. We send // a probe payment with unmodified route hints. - if !isLSP(hints, s.cfg.RouterBackend.FetchChannelEndpoints) { + invoiceTargetCompressed := payReq.Destination.SerializeCompressed() + if !isLSP(hints, invoiceTargetCompressed, s.cfg.RouterBackend.HasNode) { log.Infof("No LSP detected, probing destination %x", probeRequest.Dest) @@ -569,200 +574,342 @@ func (s *Server) probePaymentRequest(ctx context.Context, paymentRequest string, return s.sendProbePayment(ctx, probeRequest) } - // If the heuristic indicates an LSP we modify the route hints to allow - // probing the LSP. - lspAdjustedRouteHints, lspHint, err := prepareLspRouteHints( - hints, *payReq.MilliSat, + // If the heuristic indicates an LSP, we filter and group route hints by + // public LSP nodes, then probe each unique LSP separately and return + // the cheapest route. + lspGroups, err := prepareLspRouteHints( + hints, *payReq.MilliSat, s.cfg.RouterBackend.HasNode, ) if err != nil { return nil, err } - // Set the destination to the LSP node ID. - lspDest := lspHint.NodeID.SerializeCompressed() - probeRequest.Dest = lspDest + log.Infof("LSP detected, found %d unique public LSP node(s) to probe", + len(lspGroups)) - log.Infof("LSP detected, probing LSP with destination: %x", lspDest) - - // The adjusted route hints serve the payment probe to find the last - // public hop to the LSP on the route. - if len(lspAdjustedRouteHints) > 0 { - probeRequest.RouteHints = invoicesrpc.CreateRPCRouteHints( - lspAdjustedRouteHints, - ) + // Probe up to MaxLspsToProbe LSPs and track the most expensive route + // for worst-case fee estimation. + if len(lspGroups) > MaxLspsToProbe { + log.Debugf("Limiting LSP probes from %d to %d for worst-case "+ + "fee estimation", len(lspGroups), MaxLspsToProbe) } + var ( + worstCaseResp *RouteFeeResponse + worstCaseLspDest route.Vertex + probeCount int + ) - // The payment probe will be able to calculate the fee up until the LSP - // node. The fee of the last hop has to be calculated manually. Since - // the last hop's fee amount has to be sent across the payment path we - // have to add it to the original payment amount. Only then will the - // payment probe be able to determine the correct fee to the last hop - // prior to the private destination. For example, if the user wants to - // send 1000 sats to a private destination and the last hop's fee is 10 - // sats, then 1010 sats will have to arrive at the last hop. This means - // that the probe has to be dispatched with 1010 sats to correctly - // calculate the routing fee. - // - // Calculate the hop fee for the last hop manually. - hopFee := lspHint.HopFee(*payReq.MilliSat) - if err != nil { - return nil, err - } + for lspKey, group := range lspGroups { + if probeCount >= MaxLspsToProbe { + break + } + probeCount++ - // Add the last hop's fee to the requested payment amount that we want - // to get an estimate for. - probeRequest.AmtMsat += int64(hopFee) + lspHint := group.LspHopHint - // Use the hop hint's cltv delta as the payment request's final cltv - // delta. The actual final cltv delta of the invoice will be added to - // the payment probe's cltv delta. - probeRequest.FinalCltvDelta = int32(lspHint.CLTVExpiryDelta) + log.Infof("Probing LSP with destination: %v", lspKey) - // Dispatch the payment probe with adjusted fee amount. - resp, err := s.sendProbePayment(ctx, probeRequest) - if err != nil { - return nil, fmt.Errorf("failed to send probe payment to "+ - "LSP with destination %x: %w", lspDest, err) - } + // Create a new probe request for this LSP. + lspProbeRequest := &SendPaymentRequest{ + TimeoutSeconds: probeRequest.TimeoutSeconds, + Dest: lspKey[:], + MaxParts: probeRequest.MaxParts, + AllowSelfPayment: probeRequest.AllowSelfPayment, + AmtMsat: amtMsat, + PaymentHash: probeRequest.PaymentHash, + FeeLimitSat: probeRequest.FeeLimitSat, + FinalCltvDelta: int32(lspHint.CLTVExpiryDelta), + DestFeatures: probeRequest.DestFeatures, + } - // If the payment probe failed we only return the failure reason and - // leave the probe result params unaltered. - if resp.FailureReason != lnrpc.PaymentFailureReason_FAILURE_REASON_NONE { //nolint:ll - return resp, nil - } + // Copy the payment address if present. + if len(probeRequest.PaymentAddr) > 0 { + copy( + lspProbeRequest.PaymentAddr, + probeRequest.PaymentAddr, + ) + } - // The probe succeeded, so we can add the last hop's fee to fee the - // payment probe returned. - resp.RoutingFeeMsat += int64(hopFee) + // Set the adjusted route hints for this LSP. + if len(group.AdjustedRouteHints) > 0 { + lspProbeRequest.RouteHints = invoicesrpc. + CreateRPCRouteHints(group.AdjustedRouteHints) + } - // Add the final cltv delta of the invoice to the payment probe's total - // cltv delta. This is the cltv delta for the hop behind the LSP. - resp.TimeLockDelay += int64(payReq.MinFinalCLTVExpiry()) + // Calculate the hop fee for the last hop manually. + hopFee := lspHint.HopFee(*payReq.MilliSat) - return resp, nil -} + // Add the last hop's fee to the probe amount. + lspProbeRequest.AmtMsat += int64(hopFee) -// isLSP checks if the route hints indicate an LSP. An LSP is indicated with -// true if the destination hop hint in each route hint has the same node id, -// false otherwise. If the destination hop hint of any route hint contains a -// public channel, the function returns false because we can directly send a -// probe to the final destination. -func isLSP(routeHints [][]zpay32.HopHint, - fetchChannelEndpoints FetchChannelEndpoints) bool { - - if len(routeHints) == 0 || len(routeHints[0]) == 0 { - return false - } - - destHopHint := routeHints[0][len(routeHints[0])-1] - - // If the destination hop hint of the first route hint contains a public - // channel we can send a probe to it directly, hence we don't signal an - // LSP. - _, _, err := fetchChannelEndpoints(destHopHint.ChannelID) - if err == nil { - return false - } - - for i := 1; i < len(routeHints); i++ { - // Skip empty route hints. - if len(routeHints[i]) == 0 { + // Dispatch the payment probe for this LSP. + resp, err := s.sendProbePayment(ctx, lspProbeRequest) + if err != nil { + log.Warnf("Failed to probe LSP %v: %v", lspKey, err) continue } - lastHop := routeHints[i][len(routeHints[i])-1] + // If the probe failed, skip this LSP. + if resp.FailureReason != + lnrpc.PaymentFailureReason_FAILURE_REASON_NONE { - // If the last hop hint of any route hint contains a public - // channel we can send a probe to it directly, hence we don't - // signal an LSP. - _, _, err = fetchChannelEndpoints(lastHop.ChannelID) - if err == nil { - return false + log.Debugf("Probe to LSP %v failed with reason: %v", + lspKey, resp.FailureReason) + + continue } - matchesDestNode := bytes.Equal( - lastHop.NodeID.SerializeCompressed(), - destHopHint.NodeID.SerializeCompressed(), - ) - if !matchesDestNode { + // The probe succeeded, add the last hop's fee. + resp.RoutingFeeMsat += int64(hopFee) + + // Add the final cltv delta of the invoice. + resp.TimeLockDelay += int64(payReq.MinFinalCLTVExpiry()) + + log.Infof("Probe to LSP %v succeeded with fee: %d msat", + lspKey, resp.RoutingFeeMsat) + + // Track the most expensive route for worst-case estimation. + // We solely consider the routing fee for the worst-case + // estimation. + if worstCaseResp == nil || + resp.RoutingFeeMsat > worstCaseResp.RoutingFeeMsat { + + if worstCaseResp != nil { + log.Debugf("LSP %v has higher fee "+ + "(%d msat) than current worst-case "+ + "%v (%d msat), updating worst-case "+ + "estimate", lspKey, + resp.RoutingFeeMsat, worstCaseLspDest, + worstCaseResp.RoutingFeeMsat) + } + + worstCaseResp = resp + worstCaseLspDest = lspKey + } else { + log.Debugf("LSP %v fee (%d msat) is lower than "+ + "current worst-case %v (%d msat), keeping "+ + "worst-case estimate", lspKey, + resp.RoutingFeeMsat, worstCaseLspDest, + worstCaseResp.RoutingFeeMsat) + } + } + + // If no LSP probe succeeded, return an error. + if worstCaseResp == nil { + return nil, fmt.Errorf("all LSP probe payments failed") + } + + log.Infof("Returning worst-case route via LSP %v with fee: %d msat, "+ + "timelock: %d", worstCaseLspDest, worstCaseResp.RoutingFeeMsat, + worstCaseResp.TimeLockDelay) + + return worstCaseResp, nil +} + +// isLSP checks if the route hints indicate an LSP setup. An LSP setup is +// identified when the invoice destination is private but the final hop in the +// route hints is a public node (the LSP). This function implements three rules: +// +// 1. If the invoice target is a public node (exists in graph) => isLsp = false +// We can route directly to the target, so no LSP is involved. +// +// 2. If at least one destination hop hint (last hop in route hint) is public +// => isLsp = true. The public destination hop is the LSP, and the actual +// invoice target is a private node behind it. +// +// 3. If all destination hop hints are private nodes => isLsp = false. +// We assume this is NOT an LSP setup. Instead, we expect the route hints +// contain public nodes earlier in the path (not the final hop) that our +// pathfinder can route to. For example: +// The pathfinder will route to PublicNode and use the hints from there. +// Note: If no public nodes exist anywhere in the route hints, the +// destination would be unreachable (malformed invoice), but we don't +// validate that here. +func isLSP(routeHints [][]zpay32.HopHint, invoiceTarget []byte, + hasNode HasNode) bool { + + if len(routeHints) == 0 || len(routeHints[0]) == 0 { + log.Debugf("No route hints provided, this is not an LSP setup") + return false + } + + // Rule 1: If the invoice target is a public node (exists in the graph), + // we can route directly to it, so it's not an LSP setup. + if len(invoiceTarget) > 0 { + var targetVertex route.Vertex + copy(targetVertex[:], invoiceTarget) + + isPublic, err := hasNode(targetVertex) + if err != nil { + log.Warnf("Failed to check if invoice target %x is "+ + "public: %v", invoiceTarget, err) + + return false + } + if isPublic { + log.Infof("Invoice target %x is a public node in the "+ + "graph, this is NOT an LSP setup", + invoiceTarget) + return false } } - // We ensured that the destination hop hint doesn't contain a public - // channel, and that all destination hop hints of all route hints match, - // so we signal an LSP. - return true + for _, hopHints := range routeHints { + // Skip empty route hints. + if len(hopHints) == 0 { + continue + } + + lastHop := hopHints[len(hopHints)-1] + lastHopNodeCompressed := lastHop.NodeID.SerializeCompressed() + + // Check if this destination hop hint node is public. + // Rule 2: If we find a public node, we can exit early. + var lastHopVertex route.Vertex + copy(lastHopVertex[:], lastHopNodeCompressed) + + isPublic, err := hasNode(lastHopVertex) + if err != nil { + log.Warnf("Failed to check if destination hop "+ + "hint %x is public: %v", lastHopNodeCompressed, + err) + + continue + } + if isPublic { + log.Infof("Destination hop hint %x is a public node, "+ + "this is an LSP setup", lastHopNodeCompressed) + + return true + } + } + + // Rule 3: If all destination hop hints are private nodes (not in the + // graph), this is NOT an LSP setup. We assume the route hints contain + // public nodes earlier in the path that we can route through using + // standard pathfinding with the hints. + log.Infof("All destination hop hints are private, this is NOT an " + + "LSP setup") + + return false +} + +// LspRouteGroup represents a group of route hints that share the same public +// LSP destination node. This is needed when probing LSPs separately to find +// the cheapest route. +type LspRouteGroup struct { + // LspHopHint is the hop hint for the LSP node with worst-case fees and + // CLTV delta. + LspHopHint *zpay32.HopHint + + // AdjustedRouteHints are the route hints with the LSP hop stripped off. + AdjustedRouteHints [][]zpay32.HopHint } // prepareLspRouteHints assumes that the isLsp heuristic returned true for the -// route hints passed in here. It constructs a modified list of route hints that -// allows the caller to probe the LSP, which itself is returned as a separate -// hop hint. +// route hints passed in here. It filters route hints to only include those with +// public destination nodes, groups them by unique LSP node, and returns a map +// of LSP groups keyed by the LSP node's compressed public key. func prepareLspRouteHints(routeHints [][]zpay32.HopHint, - amt lnwire.MilliSatoshi) ([][]zpay32.HopHint, *zpay32.HopHint, error) { + amt lnwire.MilliSatoshi, + hasNode HasNode) (map[route.Vertex]*LspRouteGroup, error) { + // This should never happen, but we check for it for completeness. + // Because the isLSP heuristic already checked that the route hints are + // not empty. if len(routeHints) == 0 { - return nil, nil, fmt.Errorf("no route hints provided") + return nil, fmt.Errorf("no route hints provided") } - // Create the LSP hop hint. We are probing for the worst case fee and - // cltv delta. So we look for the max values amongst all LSP hop hints. - refHint := routeHints[0][len(routeHints[0])-1] - refHint.CLTVExpiryDelta = maxLspCltvDelta(routeHints) - refHint.FeeBaseMSat, refHint.FeeProportionalMillionths = maxLspFee( - routeHints, amt, - ) + // Map to group route hints by LSP node pubkey. + lspGroups := make(map[route.Vertex]*LspRouteGroup) - // We construct a modified list of route hints that allows the caller to - // probe the LSP. - adjustedHints := make([][]zpay32.HopHint, 0, len(routeHints)) + for _, routeHint := range routeHints { + // Skip empty route hints. + if len(routeHint) == 0 { + continue + } - // Strip off the LSP hop hint from all route hints. - for i := 0; i < len(routeHints); i++ { - hint := routeHints[i] - if len(hint) > 1 { - adjustedHints = append( - adjustedHints, hint[:len(hint)-1], + // Get the destination hop hint (last hop in the route). + destHop := routeHint[len(routeHint)-1] + destNodeCompressed := destHop.NodeID.SerializeCompressed() + + // Check if this destination node is public. + var destVertex route.Vertex + copy(destVertex[:], destNodeCompressed) + + isPublic, err := hasNode(destVertex) + if err != nil { + log.Warnf("Failed to check if dest hop hint %x is "+ + "public: %v", destNodeCompressed, err) + + continue + } + + // Skip private destination nodes - we only probe public LSPs. + if !isPublic { + log.Debugf("Skipping route hint with private dest "+ + "node %x", destNodeCompressed) + + continue + } + + // Use the compressed pubkey as the map key. + var lspKey route.Vertex + copy(lspKey[:], destNodeCompressed) + + // Get or create the LSP group for this node. + group, exists := lspGroups[lspKey] + if !exists { + //nolint:ll + lspHop := zpay32.HopHint{ + NodeID: destHop.NodeID, + ChannelID: destHop.ChannelID, + FeeBaseMSat: destHop.FeeBaseMSat, + FeeProportionalMillionths: destHop.FeeProportionalMillionths, + CLTVExpiryDelta: destHop.CLTVExpiryDelta, + } + group = &LspRouteGroup{ + LspHopHint: &lspHop, + AdjustedRouteHints: make([][]zpay32.HopHint, 0), + } + lspGroups[lspKey] = group + } + + // Update the LSP hop hint with worst-case (max) fees and CLTV. + hopFee := destHop.HopFee(amt) + currentMaxFee := group.LspHopHint.HopFee(amt) + if hopFee > currentMaxFee { + group.LspHopHint.FeeBaseMSat = destHop.FeeBaseMSat + group.LspHopHint.FeeProportionalMillionths = destHop. + FeeProportionalMillionths + } + + if destHop.CLTVExpiryDelta > group.LspHopHint.CLTVExpiryDelta { + group.LspHopHint.CLTVExpiryDelta = destHop. + CLTVExpiryDelta + } + + // Add the route hint with the LSP hop stripped off (if there + // are hops before the LSP). + if len(routeHint) > 1 { + group.AdjustedRouteHints = append( + group.AdjustedRouteHints, + routeHint[:len(routeHint)-1], ) } } - return adjustedHints, &refHint, nil -} - -// maxLspFee returns base fee and fee rate amongst all LSP route hints that -// results in the overall highest fee for the given amount. -func maxLspFee(routeHints [][]zpay32.HopHint, amt lnwire.MilliSatoshi) (uint32, - uint32) { - - var maxFeePpm uint32 - var maxBaseFee uint32 - var maxTotalFee lnwire.MilliSatoshi - for _, rh := range routeHints { - lastHop := rh[len(rh)-1] - lastHopFee := lastHop.HopFee(amt) - if lastHopFee > maxTotalFee { - maxTotalFee = lastHopFee - maxBaseFee = lastHop.FeeBaseMSat - maxFeePpm = lastHop.FeeProportionalMillionths - } + if len(lspGroups) == 0 { + return nil, fmt.Errorf("no public LSP nodes found in " + + "route hints") } - return maxBaseFee, maxFeePpm -} + log.Infof("Found %d unique public LSP node(s) in route hints", + len(lspGroups)) -// maxLspCltvDelta returns the maximum cltv delta amongst all LSP route hints. -func maxLspCltvDelta(routeHints [][]zpay32.HopHint) uint16 { - var maxCltvDelta uint16 - for _, rh := range routeHints { - rhLastHop := rh[len(rh)-1] - if rhLastHop.CLTVExpiryDelta > maxCltvDelta { - maxCltvDelta = rhLastHop.CLTVExpiryDelta - } - } - - return maxCltvDelta + return lspGroups, nil } // probePaymentStream is a custom implementation of the grpc.ServerStream diff --git a/lnrpc/routerrpc/router_server_test.go b/lnrpc/routerrpc/router_server_test.go index 477a9b75c..a46a12940 100644 --- a/lnrpc/routerrpc/router_server_test.go +++ b/lnrpc/routerrpc/router_server_test.go @@ -1,12 +1,12 @@ package routerrpc import ( + "bytes" "context" "testing" "time" "github.com/btcsuite/btcd/btcec/v2" - graphdb "github.com/lightningnetwork/lnd/graph/db" "github.com/lightningnetwork/lnd/lnrpc" "github.com/lightningnetwork/lnd/lnwire" paymentsdb "github.com/lightningnetwork/lnd/payments/db" @@ -220,12 +220,18 @@ func TestTrackPaymentsNoInflightUpdates(t *testing.T) { require.Equal(t, lnrpc.Payment_SUCCEEDED, payment.Status) } -// TestIsLsp tests the isLSP heuristic. Combinations of different route hints -// with different fees and cltv deltas are tested to ensure that the heuristic -// correctly identifies whether a route leads to an LSP or not. +// TestIsLsp tests the isLSP heuristic. It validates all three LSP detection +// rules: +// Rule 1: Invoice target is public => not LSP. +// Rule 2: All destination hop hints are private => not LSP (Boltz case). +// Rule 3: At least one destination hop hint is public => LSP (Muun case). func TestIsLsp(t *testing.T) { - probeAmtMsat := lnwire.MilliSatoshi(1_000_000) - + // Setup test nodes: + // - Alice: public node (in graph) + // - Bob: private node + // - Carol: private node + // - Dave: public node (in graph) + // - Eve: private node alicePrivKey, err := btcec.NewPrivateKey() require.NoError(t, err) alicePubKey := alicePrivKey.PubKey() @@ -242,216 +248,519 @@ func TestIsLsp(t *testing.T) { require.NoError(t, err) davePubKey := davePrivKey.PubKey() - var ( - aliceHopHint = zpay32.HopHint{ - NodeID: alicePubKey, - FeeBaseMSat: 100, - FeeProportionalMillionths: 1_000, - ChannelID: 421337, - } + evePrivKey, err := btcec.NewPrivateKey() + require.NoError(t, err) + evePubKey := evePrivKey.PubKey() - bobHopHint = zpay32.HopHint{ - NodeID: bobPubKey, - FeeBaseMSat: 2_000, - FeeProportionalMillionths: 2_000, - CLTVExpiryDelta: 288, - ChannelID: 815, - } + // Create hop hints for each node. + aliceHopHint := zpay32.HopHint{ + NodeID: alicePubKey, + FeeBaseMSat: 100, + FeeProportionalMillionths: 1_000, + CLTVExpiryDelta: 40, + ChannelID: 1, + } - carolHopHint = zpay32.HopHint{ - NodeID: carolPubKey, - FeeBaseMSat: 2_000, - FeeProportionalMillionths: 2_000, - ChannelID: 815, - } + bobHopHint := zpay32.HopHint{ + NodeID: bobPubKey, + FeeBaseMSat: 2_000, + FeeProportionalMillionths: 2_000, + CLTVExpiryDelta: 144, + ChannelID: 2, + } - daveHopHint = zpay32.HopHint{ - NodeID: davePubKey, - FeeBaseMSat: 2_000, - FeeProportionalMillionths: 2_000, - ChannelID: 815, - } + carolHopHint := zpay32.HopHint{ + NodeID: carolPubKey, + FeeBaseMSat: 1_500, + FeeProportionalMillionths: 1_500, + CLTVExpiryDelta: 144, + ChannelID: 3, + } - publicChannelID = uint64(42) - daveHopHintPublicChan = zpay32.HopHint{ - NodeID: davePubKey, - FeeBaseMSat: 2_000, - FeeProportionalMillionths: 2_000, - ChannelID: publicChannelID, - } - ) + daveHopHint := zpay32.HopHint{ + NodeID: davePubKey, + FeeBaseMSat: 3_000, + FeeProportionalMillionths: 3_000, + CLTVExpiryDelta: 288, + ChannelID: 4, + } - bobExpensiveCopy := bobHopHint.Copy() - bobExpensiveCopy.FeeBaseMSat = 1_000_000 - bobExpensiveCopy.FeeProportionalMillionths = 1_000_000 - bobExpensiveCopy.CLTVExpiryDelta = bobHopHint.CLTVExpiryDelta - 1 + eveHopHint := zpay32.HopHint{ + NodeID: evePubKey, + FeeBaseMSat: 500, + FeeProportionalMillionths: 500, + CLTVExpiryDelta: 40, + ChannelID: 5, + } - //nolint:ll - lspTestCases := []struct { - name string - routeHints [][]zpay32.HopHint - probeAmtMsat lnwire.MilliSatoshi - isLsp bool - expectedHints [][]zpay32.HopHint - expectedLspHop *zpay32.HopHint + // Mock hasNode: returns true only for alice and dave. + hasNode := func(nodePub route.Vertex) (bool, error) { + aliceVertex := route.NewVertex(alicePubKey) + daveVertex := route.NewVertex(davePubKey) + return bytes.Equal(nodePub[:], aliceVertex[:]) || + bytes.Equal(nodePub[:], daveVertex[:]), nil + } + + tests := []struct { + name string + routeHints [][]zpay32.HopHint + invoiceTarget []byte + expectLSP bool }{ + // Edge cases. { - name: "empty route hints", - routeHints: [][]zpay32.HopHint{{}}, - probeAmtMsat: probeAmtMsat, - isLsp: false, - expectedHints: [][]zpay32.HopHint{}, - expectedLspHop: nil, + name: "no route hints", + routeHints: [][]zpay32.HopHint{}, + invoiceTarget: nil, + expectLSP: false, }, { - name: "single route hint", - routeHints: [][]zpay32.HopHint{{daveHopHint}}, - probeAmtMsat: probeAmtMsat, - isLsp: true, - expectedHints: [][]zpay32.HopHint{}, - expectedLspHop: &daveHopHint, + name: "empty route hint array", + routeHints: [][]zpay32.HopHint{{}}, + invoiceTarget: nil, + expectLSP: false, }, + + // Rule 1: Invoice target is public => NOT an LSP. + // Rationale: Can route directly to public target. { - name: "single route, multiple hints", - routeHints: [][]zpay32.HopHint{{ - aliceHopHint, bobHopHint, - }}, - probeAmtMsat: probeAmtMsat, - isLsp: true, - expectedHints: [][]zpay32.HopHint{{aliceHopHint}}, - expectedLspHop: &bobHopHint, - }, - { - name: "multiple routes, multiple hints", + name: "invoice target is public (alice)", routeHints: [][]zpay32.HopHint{ - { - aliceHopHint, bobHopHint, - }, - { - carolHopHint, bobHopHint, - }, + {bobHopHint, carolHopHint}, }, - probeAmtMsat: probeAmtMsat, - isLsp: true, - expectedHints: [][]zpay32.HopHint{ - {aliceHopHint}, {carolHopHint}, - }, - expectedLspHop: &bobHopHint, + invoiceTarget: alicePubKey.SerializeCompressed(), + expectLSP: false, }, { - name: "multiple routes, multiple hints with min length", + name: "invoice target is public with public dest hop", routeHints: [][]zpay32.HopHint{ - { - bobHopHint, - }, - { - carolHopHint, bobHopHint, - }, + {bobHopHint, daveHopHint}, }, - probeAmtMsat: probeAmtMsat, - isLsp: true, - expectedHints: [][]zpay32.HopHint{ - {carolHopHint}, - }, - expectedLspHop: &bobHopHint, + invoiceTarget: davePubKey.SerializeCompressed(), + expectLSP: false, }, { - name: "multiple routes, multiple hints, diff fees+cltv", + name: "invoice target is public with multiple routes", routeHints: [][]zpay32.HopHint{ - { - bobHopHint, - }, - { - carolHopHint, bobExpensiveCopy, - }, + {bobHopHint, carolHopHint}, + {aliceHopHint, daveHopHint}, }, - probeAmtMsat: probeAmtMsat, - isLsp: true, - expectedHints: [][]zpay32.HopHint{ - {carolHopHint}, - }, - expectedLspHop: &zpay32.HopHint{ - NodeID: bobHopHint.NodeID, - ChannelID: bobHopHint.ChannelID, - FeeBaseMSat: bobExpensiveCopy.FeeBaseMSat, - FeeProportionalMillionths: bobExpensiveCopy.FeeProportionalMillionths, - CLTVExpiryDelta: bobHopHint.CLTVExpiryDelta, + invoiceTarget: alicePubKey.SerializeCompressed(), + expectLSP: false, + }, + + // Rule 2: All destination hop hints are private => NOT an LSP. + // Rationale: The destination hop hint is private so it cannot + // be probed so we default to NOT an LSP. + { + name: "single route to private dest", + routeHints: [][]zpay32.HopHint{ + {aliceHopHint, bobHopHint}, }, + invoiceTarget: bobPubKey.SerializeCompressed(), + expectLSP: false, }, { - name: "multiple routes, different final hops", + name: "multiple routes, all to private dests", routeHints: [][]zpay32.HopHint{ - { - aliceHopHint, bobHopHint, - }, - { - carolHopHint, daveHopHint, - }, + {aliceHopHint, bobHopHint}, + {daveHopHint, carolHopHint}, }, - probeAmtMsat: probeAmtMsat, - isLsp: false, - expectedHints: [][]zpay32.HopHint{}, - expectedLspHop: nil, + invoiceTarget: nil, + expectLSP: false, }, { - name: "multiple routes, same public hops", + name: "single hop to private node", routeHints: [][]zpay32.HopHint{ - { - aliceHopHint, daveHopHintPublicChan, - }, - { - carolHopHint, daveHopHintPublicChan, - }, + {eveHopHint}, }, - probeAmtMsat: probeAmtMsat, - isLsp: false, - expectedHints: [][]zpay32.HopHint{}, - expectedLspHop: nil, + invoiceTarget: evePubKey.SerializeCompressed(), + expectLSP: false, }, { - name: "multiple routes, same public hops", + name: "all routes to same private node", routeHints: [][]zpay32.HopHint{ - { - aliceHopHint, daveHopHint, - }, - { - carolHopHint, daveHopHintPublicChan, - }, - { - aliceHopHint, daveHopHintPublicChan, - }, + {aliceHopHint, bobHopHint}, + {daveHopHint, bobHopHint}, + {carolHopHint, bobHopHint}, }, - probeAmtMsat: probeAmtMsat, - isLsp: false, - expectedHints: [][]zpay32.HopHint{}, - expectedLspHop: nil, + invoiceTarget: nil, + expectLSP: false, + }, + + // Rule 3: At least one destination hop is public => IS an LSP. + // Rationale: As long as there is at least one public + // destination route hint, it is an LSP setup and can be probed. + { + name: "single route to public dest (dave)", + routeHints: [][]zpay32.HopHint{ + {bobHopHint, daveHopHint}, + }, + invoiceTarget: evePubKey.SerializeCompressed(), + expectLSP: true, + }, + { + name: "direct hop to public LSP (alice)", + routeHints: [][]zpay32.HopHint{ + {aliceHopHint}, + }, + invoiceTarget: bobPubKey.SerializeCompressed(), + expectLSP: true, + }, + { + name: "multiple routes to same public LSP (dave)", + routeHints: [][]zpay32.HopHint{ + {bobHopHint, daveHopHint}, + {carolHopHint, daveHopHint}, + {eveHopHint, daveHopHint}, + }, + invoiceTarget: nil, + expectLSP: true, + }, + { + name: "multiple routes to different public LSPs", + routeHints: [][]zpay32.HopHint{ + {bobHopHint, aliceHopHint}, + {carolHopHint, daveHopHint}, + }, + invoiceTarget: nil, + expectLSP: true, + }, + { + name: "mixed public and private dest hops", + routeHints: [][]zpay32.HopHint{ + {aliceHopHint, bobHopHint}, + {carolHopHint, daveHopHint}, + {bobHopHint, eveHopHint}, + }, + invoiceTarget: nil, + expectLSP: true, + }, + { + name: "first route has public dest, rest private", + routeHints: [][]zpay32.HopHint{ + {bobHopHint, aliceHopHint}, + {carolHopHint, eveHopHint}, + }, + invoiceTarget: nil, + expectLSP: true, }, } - // Returns ErrEdgeNotFound for private channels. - fetchChannelEndpoints := func(chanID uint64) (route.Vertex, - route.Vertex, error) { - - if chanID == publicChannelID { - return route.Vertex{}, route.Vertex{}, nil - } - - return route.Vertex{}, route.Vertex{}, graphdb.ErrEdgeNotFound - } - - for _, tc := range lspTestCases { - t.Run(tc.name, func(t *testing.T) { - isLsp := isLSP(tc.routeHints, fetchChannelEndpoints) - require.Equal(t, tc.isLsp, isLsp) - if !tc.isLsp { - return - } - - adjustedHints, lspHint, _ := prepareLspRouteHints( - tc.routeHints, tc.probeAmtMsat, + for _, tt := range tests { + t.Run(tt.name, func(t *testing.T) { + result := isLSP( + tt.routeHints, tt.invoiceTarget, hasNode, ) - require.Equal(t, tc.expectedHints, adjustedHints) - require.Equal(t, tc.expectedLspHop, lspHint) + require.Equal(t, tt.expectLSP, result) }) } } + +// TestPrepareLspRouteHints tests the prepareLspRouteHints function to ensure +// it correctly filters, groups, and calculates worst-case fees for LSP routes. +func TestPrepareLspRouteHints(t *testing.T) { + // Setup test nodes: + // - Alice: public LSP node (in graph) + // - Bob: private node + // - Carol: private node + // - Dave: public LSP node (in graph) + // - Eve: private node + alicePrivKey, err := btcec.NewPrivateKey() + require.NoError(t, err) + alicePubKey := alicePrivKey.PubKey() + + bobPrivKey, err := btcec.NewPrivateKey() + require.NoError(t, err) + bobPubKey := bobPrivKey.PubKey() + + carolPrivKey, err := btcec.NewPrivateKey() + require.NoError(t, err) + carolPubKey := carolPrivKey.PubKey() + + davePrivKey, err := btcec.NewPrivateKey() + require.NoError(t, err) + davePubKey := davePrivKey.PubKey() + + evePrivKey, err := btcec.NewPrivateKey() + require.NoError(t, err) + evePubKey := evePrivKey.PubKey() + + // Create hop hints with varying fees and CLTV deltas. + aliceHopHint1 := zpay32.HopHint{ + NodeID: alicePubKey, + FeeBaseMSat: 100, + FeeProportionalMillionths: 1_000, + CLTVExpiryDelta: 40, + ChannelID: 1, + } + + aliceHopHint2 := zpay32.HopHint{ + NodeID: alicePubKey, + FeeBaseMSat: 200, + FeeProportionalMillionths: 2_000, + CLTVExpiryDelta: 80, + ChannelID: 2, + } + + bobHopHint := zpay32.HopHint{ + NodeID: bobPubKey, + FeeBaseMSat: 500, + FeeProportionalMillionths: 500, + CLTVExpiryDelta: 144, + ChannelID: 3, + } + + carolHopHint := zpay32.HopHint{ + NodeID: carolPubKey, + FeeBaseMSat: 300, + FeeProportionalMillionths: 300, + CLTVExpiryDelta: 40, + ChannelID: 4, + } + + daveHopHint1 := zpay32.HopHint{ + NodeID: davePubKey, + FeeBaseMSat: 1_000, + FeeProportionalMillionths: 1_000, + CLTVExpiryDelta: 144, + ChannelID: 5, + } + + daveHopHint2 := zpay32.HopHint{ + NodeID: davePubKey, + FeeBaseMSat: 2_000, + FeeProportionalMillionths: 500, + CLTVExpiryDelta: 288, + ChannelID: 6, + } + + eveHopHint := zpay32.HopHint{ + NodeID: evePubKey, + FeeBaseMSat: 100, + FeeProportionalMillionths: 100, + CLTVExpiryDelta: 40, + ChannelID: 7, + } + + // Mock hasNode: returns true only for alice and dave. + hasNode := func(nodePub route.Vertex) (bool, error) { + aliceVertex := route.NewVertex(alicePubKey) + daveVertex := route.NewVertex(davePubKey) + return bytes.Equal(nodePub[:], aliceVertex[:]) || + bytes.Equal(nodePub[:], daveVertex[:]), nil + } + + amt := lnwire.MilliSatoshi(1_000_000) + + tests := []struct { + name string + routeHints [][]zpay32.HopHint + expectedGrps int + validateFunc func(t *testing.T, + groups map[route.Vertex]*LspRouteGroup) + }{ + { + name: "single public LSP with one route", + routeHints: [][]zpay32.HopHint{ + {bobHopHint, aliceHopHint1}, + }, + expectedGrps: 1, + validateFunc: func(t *testing.T, + groups map[route.Vertex]*LspRouteGroup) { + + require.Len(t, groups, 1) + + // Find alice's group. + aliceKey := route.NewVertex(alicePubKey) + group, ok := groups[aliceKey] + require.True(t, ok, "alice group not found") + + // Verify LSP hop hint. + require.Equal(t, aliceHopHint1.FeeBaseMSat, + group.LspHopHint.FeeBaseMSat) + require.Equal(t, aliceHopHint1.CLTVExpiryDelta, + group.LspHopHint.CLTVExpiryDelta) + + // Verify adjusted route hints. + require.Len(t, group.AdjustedRouteHints, 1) + require.Len(t, group.AdjustedRouteHints[0], 1) + require.Equal(t, bobHopHint.NodeID, + group.AdjustedRouteHints[0][0].NodeID) + }, + }, + { + name: "single LSP with multiple routes, same fees", + routeHints: [][]zpay32.HopHint{ + {bobHopHint, aliceHopHint1}, + {carolHopHint, aliceHopHint1}, + }, + expectedGrps: 1, + validateFunc: func(t *testing.T, + groups map[route.Vertex]*LspRouteGroup) { + + aliceKey := route.NewVertex(alicePubKey) + group, ok := groups[aliceKey] + require.True(t, ok, "alice group not found") + + // Should have 2 adjusted route hints. + require.Len(t, group.AdjustedRouteHints, 2) + + // Fees should match the single hop hint. + require.Equal(t, aliceHopHint1.FeeBaseMSat, + group.LspHopHint.FeeBaseMSat) + require.Equal(t, aliceHopHint1.CLTVExpiryDelta, + group.LspHopHint.CLTVExpiryDelta) + }, + }, + { + name: "single LSP with different fees, uses worst case", + routeHints: [][]zpay32.HopHint{ + {bobHopHint, aliceHopHint1}, + {carolHopHint, aliceHopHint2}, + }, + expectedGrps: 1, + validateFunc: func(t *testing.T, + groups map[route.Vertex]*LspRouteGroup) { + + aliceKey := route.NewVertex(alicePubKey) + group, ok := groups[aliceKey] + require.True(t, ok, "alice group not found") + + // Should use worst-case (higher) fees. + fee1 := aliceHopHint1.HopFee(amt) + fee2 := aliceHopHint2.HopFee(amt) + require.Greater(t, fee2, fee1, + "hint2 should have higher fees") + + // Group should have hint2's fees. + require.Equal(t, aliceHopHint2.FeeBaseMSat, + group.LspHopHint.FeeBaseMSat) + + //nolint:ll + require.Equal(t, + aliceHopHint2.FeeProportionalMillionths, + group.LspHopHint.FeeProportionalMillionths) + + // Should use worst-case CLTV delta. + require.Equal(t, aliceHopHint2.CLTVExpiryDelta, + group.LspHopHint.CLTVExpiryDelta) + }, + }, + { + name: "multiple public LSPs", + routeHints: [][]zpay32.HopHint{ + {bobHopHint, aliceHopHint1}, + {carolHopHint, daveHopHint1}, + }, + expectedGrps: 2, + validateFunc: func(t *testing.T, + groups map[route.Vertex]*LspRouteGroup) { + + require.Len(t, groups, 2) + + aliceKey := route.NewVertex(alicePubKey) + daveKey := route.NewVertex(davePubKey) + + _, hasAlice := groups[aliceKey] + _, hasDave := groups[daveKey] + require.True(t, hasAlice, "alice group missing") + require.True(t, hasDave, "dave group missing") + }, + }, + { + name: "filters out private dest hops", + routeHints: [][]zpay32.HopHint{ + {aliceHopHint1, bobHopHint}, + {carolHopHint, daveHopHint1}, + {bobHopHint, eveHopHint}, + }, + expectedGrps: 1, + validateFunc: func(t *testing.T, + groups map[route.Vertex]*LspRouteGroup) { + + require.Len(t, groups, 1) + + daveKey := route.NewVertex(davePubKey) + group, ok := groups[daveKey] + require.True(t, ok, "dave group not found") + + // Only one route hint should remain + require.Len(t, group.AdjustedRouteHints, 1) + }, + }, + { + name: "multiple routes to same LSP with varying CLTV", + routeHints: [][]zpay32.HopHint{ + {bobHopHint, daveHopHint1}, + {carolHopHint, daveHopHint2}, + }, + expectedGrps: 1, + validateFunc: func(t *testing.T, + groups map[route.Vertex]*LspRouteGroup) { + + daveKey := route.NewVertex(davePubKey) + group, ok := groups[daveKey] + require.True(t, ok, "dave group not found") + + // Should use maximum CLTV delta. + require.Equal(t, daveHopHint2.CLTVExpiryDelta, + group.LspHopHint.CLTVExpiryDelta) + }, + }, + { + name: "single hop to public LSP", + routeHints: [][]zpay32.HopHint{ + {aliceHopHint1}, + }, + expectedGrps: 1, + validateFunc: func(t *testing.T, + groups map[route.Vertex]*LspRouteGroup) { + + aliceKey := route.NewVertex(alicePubKey) + group, ok := groups[aliceKey] + require.True(t, ok, "alice group not found") + + // No adjusted hints since it's a direct hop + require.Len(t, group.AdjustedRouteHints, 0) + }, + }, + } + + for _, tt := range tests { + t.Run(tt.name, func(t *testing.T) { + groups, err := prepareLspRouteHints( + tt.routeHints, amt, hasNode, + ) + require.NoError(t, err) + require.Len(t, groups, tt.expectedGrps) + + // Run custom validation if provided. + if tt.validateFunc != nil { + tt.validateFunc(t, groups) + } + }) + } + + // Error cases which in operation should never happen because we always + // call isLSP first to check if the route hints are an LSP setup. + t.Run("error: no route hints", func(t *testing.T) { + _, err := prepareLspRouteHints( + [][]zpay32.HopHint{}, amt, hasNode, + ) + require.Error(t, err) + require.Contains(t, err.Error(), "no route hints") + }) + + t.Run("error: no public LSP nodes found", func(t *testing.T) { + // All private destination hops. If all destination hops are + // private we cannot probe any LSPs so we return an error. + routeHints := [][]zpay32.HopHint{ + {aliceHopHint1, bobHopHint}, + {daveHopHint1, carolHopHint}, + } + _, err := prepareLspRouteHints(routeHints, amt, hasNode) + require.Error(t, err) + require.Contains(t, err.Error(), "no public LSP nodes found") + }) +}