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Merge pull request #9316 from ziggie1984/fix-blindedpath-mc

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routing: fix mc blinded path behaviour.
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Oliver Gugger 2024-12-10 20:22:15 +01:00 • committed by GitHub
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9 changed files with 576 additions and 117 deletions
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4
docs/release-notes/release-notes-0.18.4.md
View file

@ -26,6 +26,9 @@
* [Fixed a bug](https://github.com/lightningnetwork/lnd/pull/9324) to prevent
potential deadlocks when LND depends on external components (e.g. aux
components, hooks).
* [Make sure blinded payment failures are handled correctly in the mission
controller](https://github.com/lightningnetwork/lnd/pull/9316).
# New Features
@ -121,4 +124,5 @@ types in a series of changes:
* George Tsagkarelis
* Olaoluwa Osuntokun
* Oliver Gugger
* Ziggie

4
docs/release-notes/release-notes-0.19.0.md
View file

@ -60,7 +60,7 @@
* [Make the contract resolutions for the channel arbitrator optional](
https://github.com/lightningnetwork/lnd/pull/9253)
* [Fixed a bug](https://github.com/lightningnetwork/lnd/pull/9322) that caused
* [Fixed a bug](https://github.com/lightningnetwork/lnd/pull/9322) that caused
estimateroutefee to ignore the default payment timeout.
# New Features
@ -80,7 +80,7 @@
## RPC Additions
* [Add a new rpc endpoint](https://github.com/lightningnetwork/lnd/pull/8843)
`BumpForceCloseFee` which moves the functionality soley available in the
`BumpForceCloseFee` which moves the functionality solely available in the
`lncli` to LND hence making it more universal.
* [The `walletrpc.FundPsbt` RPC method now has an option to specify the fee as

6
input/script_utils.go
View file

@ -29,9 +29,9 @@ var (
SequenceLockTimeSeconds = uint32(1 << 22)
)
// mustParsePubKey parses a hex encoded public key string into a public key and
// MustParsePubKey parses a hex encoded public key string into a public key and
// panic if parsing fails.
func mustParsePubKey(pubStr string) btcec.PublicKey {
func MustParsePubKey(pubStr string) btcec.PublicKey {
pubBytes, err := hex.DecodeString(pubStr)
if err != nil {
panic(err)
@ -55,7 +55,7 @@ var (
// https://github.com/lightninglabs/lightning-node-connect/tree/
// master/mailbox/numsgen, with the seed phrase "Lightning Simple
// Taproot".
TaprootNUMSKey = mustParsePubKey(TaprootNUMSHex)
TaprootNUMSKey = MustParsePubKey(TaprootNUMSHex)
)
// Signature is an interface for objects that can populate signatures during

223
routing/blinding.go
View file

@ -1,17 +1,27 @@
package routing
import (
"bytes"
"errors"
"fmt"
"github.com/btcsuite/btcd/btcec/v2"
"github.com/decred/dcrd/dcrec/secp256k1/v4"
sphinx "github.com/lightningnetwork/lightning-onion"
"github.com/lightningnetwork/lnd/fn/v2"
"github.com/lightningnetwork/lnd/graph/db/models"
"github.com/lightningnetwork/lnd/input"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/routing/route"
)
// BlindedPathNUMSHex is the hex encoded version of the blinded path target
// NUMs key (in compressed format) which has no known private key.
// This was generated using the following script:
// https://github.com/lightninglabs/lightning-node-connect/tree/master/
// mailbox/numsgen, with the seed phrase "Lightning Blinded Path".
const BlindedPathNUMSHex = "02667a98ef82ecb522f803b17a74f14508a48b25258f9831" +
"dd6e95f5e299dfd54e"
var (
// ErrNoBlindedPath is returned when the blinded path in a blinded
// payment is missing.
@ -25,6 +35,14 @@ var (
// ErrHTLCRestrictions is returned when a blinded path has invalid
// HTLC maximum and minimum values.
ErrHTLCRestrictions = errors.New("invalid htlc minimum and maximum")
// BlindedPathNUMSKey is a NUMS key (nothing up my sleeves number) that
// has no known private key.
BlindedPathNUMSKey = input.MustParsePubKey(BlindedPathNUMSHex)
// CompressedBlindedPathNUMSKey is the compressed version of the
// BlindedPathNUMSKey.
CompressedBlindedPathNUMSKey = BlindedPathNUMSKey.SerializeCompressed()
)
// BlindedPaymentPathSet groups the data we need to handle sending to a set of
@ -70,7 +88,9 @@ type BlindedPaymentPathSet struct {
}
// NewBlindedPaymentPathSet constructs a new BlindedPaymentPathSet from a set of
// BlindedPayments.
// BlindedPayments. For blinded paths which have more than one single hop a
// dummy hop via a NUMS key is appeneded to allow for MPP path finding via
// multiple blinded paths.
func NewBlindedPaymentPathSet(paths []*BlindedPayment) (*BlindedPaymentPathSet,
error) {
@ -103,36 +123,53 @@ func NewBlindedPaymentPathSet(paths []*BlindedPayment) (*BlindedPaymentPathSet,
}
}
// Derive an ephemeral target priv key that will be injected into each
// blinded path final hop.
targetPriv, err := btcec.NewPrivateKey()
if err != nil {
return nil, err
// Deep copy the paths to avoid mutating the original paths.
pathSet := make([]*BlindedPayment, len(paths))
for i, path := range paths {
pathSet[i] = path.deepCopy()
}
targetPub := targetPriv.PubKey()
var (
pathSet = paths
finalCLTVDelta uint16
)
// If any provided blinded path only has a single hop (ie, the
// destination node is also the introduction node), then we discard all
// other paths since we know the real pub key of the destination node.
// We also then set the final CLTV delta to the path's delta since
// there are no other edge hints that will account for it. For a single
// hop path, there is also no need for the pseudo target pub key
// replacement, so our target pub key in this case just remains the
// real introduction node ID.
for _, path := range paths {
if len(path.BlindedPath.BlindedHops) != 1 {
continue
// For blinded paths we use the NUMS key as a target if the blinded
// path has more hops than just the introduction node.
targetPub := &BlindedPathNUMSKey
var finalCLTVDelta uint16
// In case the paths do NOT include a single hop route we append a
// dummy hop via a NUMS key to allow for MPP path finding via multiple
// blinded paths. A unified target is needed to use all blinded paths
// during the payment lifecycle. A dummy hop is solely added for the
// path finding process and is removed after the path is found. This
// ensures that we still populate the mission control with the correct
// data and also respect these mc entries when looking for a path.
for _, path := range pathSet {
pathLength := len(path.BlindedPath.BlindedHops)
// If any provided blinded path only has a single hop (ie, the
// destination node is also the introduction node), then we
// discard all other paths since we know the real pub key of the
// destination node. We also then set the final CLTV delta to
// the path's delta since there are no other edge hints that
// will account for it.
if pathLength == 1 {
pathSet = []*BlindedPayment{path}
finalCLTVDelta = path.CltvExpiryDelta
targetPub = path.BlindedPath.IntroductionPoint
break
}
pathSet = []*BlindedPayment{path}
finalCLTVDelta = path.CltvExpiryDelta
targetPub = path.BlindedPath.IntroductionPoint
break
lastHop := path.BlindedPath.BlindedHops[pathLength-1]
path.BlindedPath.BlindedHops = append(
path.BlindedPath.BlindedHops,
&sphinx.BlindedHopInfo{
BlindedNodePub: &BlindedPathNUMSKey,
// We add the last hop's cipher text so that
// the payload size of the final hop is equal
// to the real last hop.
CipherText: lastHop.CipherText,
},
)
}
return &BlindedPaymentPathSet{
@ -198,21 +235,33 @@ func (s *BlindedPaymentPathSet) FinalCLTVDelta() uint16 {
// LargestLastHopPayloadPath returns the BlindedPayment in the set that has the
// largest last-hop payload. This is to be used for onion size estimation in
// path finding.
func (s *BlindedPaymentPathSet) LargestLastHopPayloadPath() *BlindedPayment {
func (s *BlindedPaymentPathSet) LargestLastHopPayloadPath() (*BlindedPayment,
error) {
var (
largestPath *BlindedPayment
currentMax int
)
if len(s.paths) == 0 {
return nil, fmt.Errorf("no blinded paths in the set")
}
// We set the largest path to make sure we always return a path even
// if the cipher text is empty.
largestPath = s.paths[0]
for _, path := range s.paths {
numHops := len(path.BlindedPath.BlindedHops)
lastHop := path.BlindedPath.BlindedHops[numHops-1]
if len(lastHop.CipherText) > currentMax {
largestPath = path
currentMax = len(lastHop.CipherText)
}
}
return largestPath
return largestPath, nil
}
// ToRouteHints converts the blinded path payment set into a RouteHints map so
@ -222,7 +271,7 @@ func (s *BlindedPaymentPathSet) ToRouteHints() (RouteHints, error) {
hints := make(RouteHints)
for _, path := range s.paths {
pathHints, err := path.toRouteHints(fn.Some(s.targetPubKey))
pathHints, err := path.toRouteHints()
if err != nil {
return nil, err
}
@ -239,6 +288,12 @@ func (s *BlindedPaymentPathSet) ToRouteHints() (RouteHints, error) {
return hints, nil
}
// IsBlindedRouteNUMSTargetKey returns true if the given public key is the
// NUMS key used as a target for blinded path final hops.
func IsBlindedRouteNUMSTargetKey(pk []byte) bool {
return bytes.Equal(pk, CompressedBlindedPathNUMSKey)
}
// BlindedPayment provides the path and payment parameters required to send a
// payment along a blinded path.
type BlindedPayment struct {
@ -291,6 +346,22 @@ func (b *BlindedPayment) Validate() error {
b.HtlcMaximum, b.HtlcMinimum)
}
for _, hop := range b.BlindedPath.BlindedHops {
// The first hop of the blinded path does not necessarily have
// blinded node pub key because it is the introduction point.
if hop.BlindedNodePub == nil {
continue
}
if IsBlindedRouteNUMSTargetKey(
hop.BlindedNodePub.SerializeCompressed(),
) {
return fmt.Errorf("blinded path cannot include NUMS "+
"key: %s", BlindedPathNUMSHex)
}
}
return nil
}
@ -301,11 +372,8 @@ func (b *BlindedPayment) Validate() error {
// effectively the final_cltv_delta for the receiving introduction node). In
// the case of multiple blinded hops, CLTV delta is fully accounted for in the
// hints (both for intermediate hops and the final_cltv_delta for the receiving
// node). The pseudoTarget, if provided, will be used to override the pub key
// of the destination node in the path.
func (b *BlindedPayment) toRouteHints(
pseudoTarget fn.Option[*btcec.PublicKey]) (RouteHints, error) {
// node).
func (b *BlindedPayment) toRouteHints() (RouteHints, error) {
// If we just have a single hop in our blinded route, it just contains
// an introduction node (this is a valid path according to the spec).
// Since we have the un-blinded node ID for the introduction node, we
@ -393,16 +461,77 @@ func (b *BlindedPayment) toRouteHints(
hints[fromNode] = []AdditionalEdge{lastEdge}
}
pseudoTarget.WhenSome(func(key *btcec.PublicKey) {
// For the very last hop on the path, switch out the ToNodePub
// for the pseudo target pub key.
lastEdge.policy.ToNodePubKey = func() route.Vertex {
return route.NewVertex(key)
}
// Then override the final hint with this updated edge.
hints[fromNode] = []AdditionalEdge{lastEdge}
})
return hints, nil
}
// deepCopy returns a deep copy of the BlindedPayment.
func (b *BlindedPayment) deepCopy() *BlindedPayment {
if b == nil {
return nil
}
cpyPayment := &BlindedPayment{
BaseFee: b.BaseFee,
ProportionalFeeRate: b.ProportionalFeeRate,
CltvExpiryDelta: b.CltvExpiryDelta,
HtlcMinimum: b.HtlcMinimum,
HtlcMaximum: b.HtlcMaximum,
}
// Deep copy the BlindedPath if it exists
if b.BlindedPath != nil {
cpyPayment.BlindedPath = &sphinx.BlindedPath{
BlindedHops: make([]*sphinx.BlindedHopInfo,
len(b.BlindedPath.BlindedHops)),
}
if b.BlindedPath.IntroductionPoint != nil {
cpyPayment.BlindedPath.IntroductionPoint =
copyPublicKey(b.BlindedPath.IntroductionPoint)
}
if b.BlindedPath.BlindingPoint != nil {
cpyPayment.BlindedPath.BlindingPoint =
copyPublicKey(b.BlindedPath.BlindingPoint)
}
// Copy each blinded hop info.
for i, hop := range b.BlindedPath.BlindedHops {
if hop == nil {
continue
}
cpyHop := &sphinx.BlindedHopInfo{
CipherText: hop.CipherText,
}
if hop.BlindedNodePub != nil {
cpyHop.BlindedNodePub =
copyPublicKey(hop.BlindedNodePub)
}
cpyHop.CipherText = make([]byte, len(hop.CipherText))
copy(cpyHop.CipherText, hop.CipherText)
cpyPayment.BlindedPath.BlindedHops[i] = cpyHop
}
}
// Deep copy the Features if they exist
if b.Features != nil {
cpyPayment.Features = b.Features.Clone()
}
return cpyPayment
}
// copyPublicKey makes a deep copy of a public key.
//
// TODO(ziggie): Remove this function if this is available in the btcec library.
func copyPublicKey(pk *btcec.PublicKey) *btcec.PublicKey {
var result secp256k1.JacobianPoint
pk.AsJacobian(&result)
result.ToAffine()
return btcec.NewPublicKey(&result.X, &result.Y)
}

66
routing/blinding_test.go
View file

@ -2,11 +2,11 @@ package routing
import (
"bytes"
"reflect"
"testing"
"github.com/btcsuite/btcd/btcec/v2"
sphinx "github.com/lightningnetwork/lightning-onion"
"github.com/lightningnetwork/lnd/fn/v2"
"github.com/lightningnetwork/lnd/graph/db/models"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/routing/route"
@ -129,7 +129,7 @@ func TestBlindedPaymentToHints(t *testing.T) {
HtlcMaximum: htlcMax,
Features: features,
}
hints, err := blindedPayment.toRouteHints(fn.None[*btcec.PublicKey]())
hints, err := blindedPayment.toRouteHints()
require.NoError(t, err)
require.Nil(t, hints)
@ -184,7 +184,7 @@ func TestBlindedPaymentToHints(t *testing.T) {
},
}
actual, err := blindedPayment.toRouteHints(fn.None[*btcec.PublicKey]())
actual, err := blindedPayment.toRouteHints()
require.NoError(t, err)
require.Equal(t, len(expected), len(actual))
@ -218,3 +218,63 @@ func TestBlindedPaymentToHints(t *testing.T) {
require.Equal(t, expectedHint[0], actualHint[0])
}
}
// TestBlindedPaymentDeepCopy tests the deep copy method of the BLindedPayment
// struct.
//
// TODO(ziggie): Make this a property test instead.
func TestBlindedPaymentDeepCopy(t *testing.T) {
_, pkBlind1 := btcec.PrivKeyFromBytes([]byte{1})
_, blindingPoint := btcec.PrivKeyFromBytes([]byte{2})
_, pkBlind2 := btcec.PrivKeyFromBytes([]byte{3})
// Create a test BlindedPayment with non-nil fields
original := &BlindedPayment{
BaseFee: 1000,
ProportionalFeeRate: 2000,
CltvExpiryDelta: 144,
HtlcMinimum: 1000,
HtlcMaximum: 1000000,
Features: lnwire.NewFeatureVector(nil, nil),
BlindedPath: &sphinx.BlindedPath{
IntroductionPoint: pkBlind1,
BlindingPoint: blindingPoint,
BlindedHops: []*sphinx.BlindedHopInfo{
{
BlindedNodePub: pkBlind2,
CipherText: []byte("test cipher"),
},
},
},
}
// Make a deep copy
cpyPayment := original.deepCopy()
// Test 1: Verify the copy is not the same pointer
if cpyPayment == original {
t.Fatal("deepCopy returned same pointer")
}
// Verify all fields are equal
if !reflect.DeepEqual(original, cpyPayment) {
t.Fatal("copy is not equal to original")
}
// Modify the copy and verify it doesn't affect the original
cpyPayment.BaseFee = 2000
cpyPayment.BlindedPath.BlindedHops[0].CipherText = []byte("modified")
require.NotEqual(t, original.BaseFee, cpyPayment.BaseFee)
require.NotEqual(
t,
original.BlindedPath.BlindedHops[0].CipherText,
cpyPayment.BlindedPath.BlindedHops[0].CipherText,
)
// Verify nil handling.
var nilPayment *BlindedPayment
nilCopy := nilPayment.deepCopy()
require.Nil(t, nilCopy)
}

59
routing/pathfind.go
View file

@ -158,6 +158,32 @@ func newRoute(sourceVertex route.Vertex,
)
pathLength := len(pathEdges)
// When paying to a blinded route we might have appended a dummy hop at
// the end to make MPP payments possible via all paths of the blinded
// route set. We always append a dummy hop when the internal pathfiner
// looks for a route to a blinded path which is at least one hop long
// (excluding the introduction point). We add this dummy hop so that
// we search for a universal target but also respect potential mc
// entries which might already be present for a particular blinded path.
// However when constructing the Sphinx packet we need to remove this
// dummy hop again which we do here.
//
// NOTE: The path length is always at least 1 because there must be one
// edge from the source to the destination. However we check for > 0
// just for robustness here.
if blindedPathSet != nil && pathLength > 0 {
finalBlindedPubKey := pathEdges[pathLength-1].policy.
ToNodePubKey()
if IsBlindedRouteNUMSTargetKey(finalBlindedPubKey[:]) {
// If the last hop is the NUMS key for blinded paths, we
// remove the dummy hop from the route.
pathEdges = pathEdges[:pathLength-1]
pathLength--
}
}
for i := pathLength - 1; i >= 0; i-- {
// Now we'll start to calculate the items within the per-hop
// payload for the hop this edge is leading to.
@ -319,10 +345,6 @@ func newRoute(sourceVertex route.Vertex,
dataIndex = 0
blindedPath = blindedPayment.BlindedPath
numHops = len(blindedPath.BlindedHops)
realFinal = blindedPath.BlindedHops[numHops-1].
BlindedNodePub
introVertex = route.NewVertex(
blindedPath.IntroductionPoint,
)
@ -350,11 +372,6 @@ func newRoute(sourceVertex route.Vertex,
if i != len(hops)-1 {
hop.AmtToForward = 0
hop.OutgoingTimeLock = 0
} else {
// For the final hop, we swap out the pub key
// bytes to the original destination node pub
// key for that payment path.
hop.PubKeyBytes = route.NewVertex(realFinal)
}
dataIndex++
@ -683,7 +700,10 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
// The payload size of the final hop differ from intermediate hops
// and depends on whether the destination is blinded or not.
lastHopPayloadSize := lastHopPayloadSize(r, finalHtlcExpiry, amt)
lastHopPayloadSize, err := lastHopPayloadSize(r, finalHtlcExpiry, amt)
if err != nil {
return nil, 0, err
}
// We can't always assume that the end destination is publicly
// advertised to the network so we'll manually include the target node.
@ -901,6 +921,13 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
// included. If we are coming from the source hop, the payload
// size is zero, because the original htlc isn't in the onion
// blob.
//
// NOTE: For blinded paths with the NUMS key as the last hop,
// the payload size accounts for this dummy hop which is of
// the same size as the real last hop. So we account for a
// bigger size than the route is however we accept this
// little inaccuracy here because we are over estimating by
// 1 hop.
var payloadSize uint64
if fromVertex != source {
// In case the unifiedEdge does not have a payload size
@ -1409,11 +1436,15 @@ func getProbabilityBasedDist(weight int64, probability float64,
// It depends on the tlv types which are present and also whether the hop is
// part of a blinded route or not.
func lastHopPayloadSize(r *RestrictParams, finalHtlcExpiry int32,
amount lnwire.MilliSatoshi) uint64 {
amount lnwire.MilliSatoshi) (uint64, error) {
if r.BlindedPaymentPathSet != nil {
paymentPath := r.BlindedPaymentPathSet.
paymentPath, err := r.BlindedPaymentPathSet.
LargestLastHopPayloadPath()
if err != nil {
return 0, err
}
blindedPath := paymentPath.BlindedPath.BlindedHops
blindedPoint := paymentPath.BlindedPath.BlindingPoint
@ -1428,7 +1459,7 @@ func lastHopPayloadSize(r *RestrictParams, finalHtlcExpiry int32,
}
// The final hop does not have a short chanID set.
return finalHop.PayloadSize(0)
return finalHop.PayloadSize(0), nil
}
var mpp *record.MPP
@ -1454,7 +1485,7 @@ func lastHopPayloadSize(r *RestrictParams, finalHtlcExpiry int32,
}
// The final hop does not have a short chanID set.
return finalHop.PayloadSize(0)
return finalHop.PayloadSize(0), nil
}
// overflowSafeAdd adds two MilliSatoshi values and returns the result. If an

189
routing/pathfind_test.go
View file

@ -765,6 +765,9 @@ func TestPathFinding(t *testing.T) {
}, {
name: "path finding with additional edges",
fn: runPathFindingWithAdditionalEdges,
}, {
name: "path finding with duplicate blinded hop",
fn: runPathFindingWithBlindedPathDuplicateHop,
}, {
name: "path finding with redundant additional edges",
fn: runPathFindingWithRedundantAdditionalEdges,
@ -1265,6 +1268,107 @@ func runPathFindingWithAdditionalEdges(t *testing.T, useCache bool) {
assertExpectedPath(t, graph.aliasMap, path, "songoku", "doge")
}
// runPathFindingWithBlindedPathDuplicateHop tests that in case a blinded path
// has duplicate hops that the path finding algorithm does not fail or behave
// incorrectly. This can happen because the creator of the blinded path can
// specify the same hop multiple times and this will only be detected at the
// forwarding nodes, so it is important that we can handle this case.
func runPathFindingWithBlindedPathDuplicateHop(t *testing.T, useCache bool) {
graph, err := parseTestGraph(t, useCache, basicGraphFilePath)
require.NoError(t, err, "unable to create graph")
sourceNode, err := graph.graph.SourceNode()
require.NoError(t, err, "unable to fetch source node")
paymentAmt := lnwire.NewMSatFromSatoshis(100)
songokuPubKeyBytes := graph.aliasMap["songoku"]
songokuPubKey, err := btcec.ParsePubKey(songokuPubKeyBytes[:])
require.NoError(t, err, "unable to parse public key from bytes")
_, pkb1 := btcec.PrivKeyFromBytes([]byte{2})
_, pkb2 := btcec.PrivKeyFromBytes([]byte{3})
_, blindedPoint := btcec.PrivKeyFromBytes([]byte{5})
sizeEncryptedData := 100
cipherText := bytes.Repeat(
[]byte{1}, sizeEncryptedData,
)
vb1 := route.NewVertex(pkb1)
vb2 := route.NewVertex(pkb2)
// Payments to blinded paths always pay to the NUMS target key.
dummyTarget := route.NewVertex(&BlindedPathNUMSKey)
graph.aliasMap["pkb1"] = vb1
graph.aliasMap["pkb2"] = vb2
graph.aliasMap["dummyTarget"] = dummyTarget
// Create a blinded payment with duplicate hops and make sure the
// path finding algorithm can cope with that. We add blinded hop 2
// 3 times. The path finding algorithm should create a path with a
// single hop to pkb2 (the first entry).
blindedPayment := &BlindedPayment{
BlindedPath: &sphinx.BlindedPath{
IntroductionPoint: songokuPubKey,
BlindingPoint: blindedPoint,
BlindedHops: []*sphinx.BlindedHopInfo{
{
CipherText: cipherText,
},
{
BlindedNodePub: pkb2,
CipherText: cipherText,
},
{
BlindedNodePub: pkb1,
CipherText: cipherText,
},
{
BlindedNodePub: pkb2,
CipherText: cipherText,
},
{
BlindedNodePub: &BlindedPathNUMSKey,
CipherText: cipherText,
},
{
BlindedNodePub: pkb2,
CipherText: cipherText,
},
},
},
HtlcMinimum: 1,
HtlcMaximum: 100_000_000,
CltvExpiryDelta: 140,
}
blindedPath, err := blindedPayment.toRouteHints()
require.NoError(t, err)
find := func(r *RestrictParams) (
[]*unifiedEdge, error) {
return dbFindPath(
graph.graph, blindedPath, &mockBandwidthHints{},
r, testPathFindingConfig,
sourceNode.PubKeyBytes, dummyTarget, paymentAmt,
0, 0,
)
}
// We should now be able to find a path however not the chained path
// of the blinded hops.
path, err := find(noRestrictions)
require.NoError(t, err, "unable to create route to blinded path")
// The path should represent the following hops:
// source node -> songoku -> pkb2 -> dummyTarget
assertExpectedPath(t, graph.aliasMap, path, "songoku", "pkb2",
"dummyTarget")
}
// runPathFindingWithRedundantAdditionalEdges asserts that we are able to find
// paths to nodes ignoring additional edges that are already known by self node.
func runPathFindingWithRedundantAdditionalEdges(t *testing.T, useCache bool) {
@ -3284,9 +3388,7 @@ func TestBlindedRouteConstruction(t *testing.T) {
// that make up the graph we'll give to route construction. The hints
// map is keyed by source node, so we can retrieve our blinded edges
// accordingly.
blindedEdges, err := blindedPayment.toRouteHints(
fn.None[*btcec.PublicKey](),
)
blindedEdges, err := blindedPayment.toRouteHints()
require.NoError(t, err)
carolDaveEdge := blindedEdges[carolVertex][0]
@ -3415,32 +3517,48 @@ func TestLastHopPayloadSize(t *testing.T) {
customRecords = map[uint64][]byte{
record.CustomTypeStart: {1, 2, 3},
}
sizeEncryptedData = 100
encrypedData = bytes.Repeat(
[]byte{1}, sizeEncryptedData,
encrypedDataSmall = bytes.Repeat(
[]byte{1}, 5,
)
_, blindedPoint = btcec.PrivKeyFromBytes([]byte{5})
paymentAddr = &[32]byte{1}
ampOptions = &AMPOptions{}
amtToForward = lnwire.MilliSatoshi(10000)
finalHopExpiry int32 = 144
encrypedDataLarge = bytes.Repeat(
[]byte{1}, 100,
)
_, blindedPoint = btcec.PrivKeyFromBytes([]byte{5})
paymentAddr = &[32]byte{1}
ampOptions = &AMPOptions{}
amtToForward = lnwire.MilliSatoshi(10000)
emptyEncryptedData = []byte{}
finalHopExpiry int32 = 144
oneHopPath = &sphinx.BlindedPath{
BlindedHops: []*sphinx.BlindedHopInfo{
{
CipherText: encrypedData,
CipherText: emptyEncryptedData,
},
},
BlindingPoint: blindedPoint,
}
twoHopPath = &sphinx.BlindedPath{
twoHopPathSmallHopSize = &sphinx.BlindedPath{
BlindedHops: []*sphinx.BlindedHopInfo{
{
CipherText: encrypedData,
CipherText: encrypedDataLarge,
},
{
CipherText: encrypedData,
CipherText: encrypedDataLarge,
},
},
BlindingPoint: blindedPoint,
}
twoHopPathLargeHopSize = &sphinx.BlindedPath{
BlindedHops: []*sphinx.BlindedHopInfo{
{
CipherText: encrypedDataSmall,
},
{
CipherText: encrypedDataSmall,
},
},
BlindingPoint: blindedPoint,
@ -3453,15 +3571,19 @@ func TestLastHopPayloadSize(t *testing.T) {
require.NoError(t, err)
twoHopBlindedPayment, err := NewBlindedPaymentPathSet(
[]*BlindedPayment{{BlindedPath: twoHopPath}},
[]*BlindedPayment{
{BlindedPath: twoHopPathLargeHopSize},
{BlindedPath: twoHopPathSmallHopSize},
},
)
require.NoError(t, err)
testCases := []struct {
name string
restrictions *RestrictParams
finalHopExpiry int32
amount lnwire.MilliSatoshi
name string
restrictions *RestrictParams
finalHopExpiry int32
amount lnwire.MilliSatoshi
expectedEncryptedData []byte
}{
{
name: "Non blinded final hop",
@ -3479,16 +3601,18 @@ func TestLastHopPayloadSize(t *testing.T) {
restrictions: &RestrictParams{
BlindedPaymentPathSet: oneHopBlindedPayment,
},
amount: amtToForward,
finalHopExpiry: finalHopExpiry,
amount: amtToForward,
finalHopExpiry: finalHopExpiry,
expectedEncryptedData: emptyEncryptedData,
},
{
name: "Blinded final hop of a two hop payment",
restrictions: &RestrictParams{
BlindedPaymentPathSet: twoHopBlindedPayment,
},
amount: amtToForward,
finalHopExpiry: finalHopExpiry,
amount: amtToForward,
finalHopExpiry: finalHopExpiry,
expectedEncryptedData: encrypedDataLarge,
},
}
@ -3512,16 +3636,23 @@ func TestLastHopPayloadSize(t *testing.T) {
var finalHop route.Hop
if tc.restrictions.BlindedPaymentPathSet != nil {
path := tc.restrictions.BlindedPaymentPathSet.
LargestLastHopPayloadPath()
bPSet := tc.restrictions.BlindedPaymentPathSet
path, err := bPSet.LargestLastHopPayloadPath()
require.NotNil(t, path)
require.NoError(t, err)
blindedPath := path.BlindedPath.BlindedHops
blindedPoint := path.BlindedPath.BlindingPoint
lastHop := blindedPath[len(blindedPath)-1]
require.Equal(t, lastHop.CipherText,
tc.expectedEncryptedData)
//nolint:ll
finalHop = route.Hop{
AmtToForward: tc.amount,
OutgoingTimeLock: uint32(tc.finalHopExpiry),
EncryptedData: blindedPath[len(blindedPath)-1].CipherText,
EncryptedData: lastHop.CipherText,
}
if len(blindedPath) == 1 {
finalHop.BlindingPoint = blindedPoint
@ -3541,11 +3672,11 @@ func TestLastHopPayloadSize(t *testing.T) {
payLoad, err := createHopPayload(finalHop, 0, true)
require.NoErrorf(t, err, "failed to create hop payload")
expectedPayloadSize := lastHopPayloadSize(
expectedPayloadSize, err := lastHopPayloadSize(
tc.restrictions, tc.finalHopExpiry,
tc.amount,
)
require.NoError(t, err)
require.Equal(
t, expectedPayloadSize,
uint64(payLoad.NumBytes()),

79
routing/result_interpretation.go
View file

@ -100,8 +100,27 @@ func interpretResult(rt *mcRoute,
// processSuccess processes a successful payment attempt.
func (i *interpretedResult) processSuccess(route *mcRoute) {
// For successes, all nodes must have acted in the right way. Therefore
// we mark all of them with a success result.
// For successes, all nodes must have acted in the right way.
// Therefore we mark all of them with a success result. However we need
// to handle the blinded route part separately because for intermediate
// blinded nodes the amount field is set to zero so we use the receiver
// amount.
introIdx, isBlinded := introductionPointIndex(route)
if isBlinded {
// Report success for all the pairs until the introduction
// point.
i.successPairRange(route, 0, introIdx-1)
// Handle the blinded route part.
//
// NOTE: The introIdx index here does describe the node after
// the introduction point.
i.markBlindedRouteSuccess(route, introIdx)
return
}
// Mark nodes as successful in the non-blinded case of the payment.
i.successPairRange(route, 0, len(route.hops.Val)-1)
}
@ -517,11 +536,22 @@ func (i *interpretedResult) processPaymentOutcomeIntermediate(route *mcRoute,
if introIdx == len(route.hops.Val)-1 {
i.finalFailureReason = &reasonError
} else {
// If there are other hops between the recipient and
// introduction node, then we just penalize the last
// hop in the blinded route to minimize the storage of
// results for ephemeral keys.
i.failPairBalance(route, len(route.hops.Val)-1)
// We penalize the final hop of the blinded route which
// is sufficient to not reuse this route again and is
// also more memory efficient because the other hops
// of the blinded path are ephemeral and will only be
// used in conjunction with the final hop. Moreover we
// don't want to punish the introduction node because
// the blinded failure does not necessarily mean that
// the introduction node was at fault.
//
// TODO(ziggie): Make sure we only keep mc data for
// blinded paths, in both the success and failure case,
// in memory during the time of the payment and remove
// it afterwards. Blinded paths and their blinded hop
// keys are always changing per blinded route so there
// is no point in persisting this data.
i.failBlindedRoute(route)
}
// In all other cases, we penalize the reporting node. These are all
@ -828,6 +858,41 @@ func (i *interpretedResult) successPairRange(rt *mcRoute, fromIdx, toIdx int) {
}
}
// failBlindedRoute marks a blinded route as failed for the specific amount to
// send by only punishing the last pair.
func (i *interpretedResult) failBlindedRoute(rt *mcRoute) {
// We fail the last pair of the route, in order to fail the complete
// blinded route. This is because the combination of ephemeral pubkeys
// is unique to the route. We fail the last pair in order to not punish
// the introduction node, since we don't want to disincentivize them
// from providing that service.
pair, _ := getPair(rt, len(rt.hops.Val)-1)
// Since all the hops along a blinded path don't have any amount set, we
// extract the minimal amount to punish from the value that is tried to
// be sent to the receiver.
amt := rt.hops.Val[len(rt.hops.Val)-1].amtToFwd.Val
i.pairResults[pair] = failPairResult(amt)
}
// markBlindedRouteSuccess marks the hops of the blinded route AFTER the
// introduction node as successful.
//
// NOTE: The introIdx must be the index of the first hop of the blinded route
// AFTER the introduction node.
func (i *interpretedResult) markBlindedRouteSuccess(rt *mcRoute, introIdx int) {
// For blinded hops we do not have the forwarding amount so we take the
// minimal amount which went through the route by looking at the last
// hop.
successAmt := rt.hops.Val[len(rt.hops.Val)-1].amtToFwd.Val
for idx := introIdx; idx < len(rt.hops.Val); idx++ {
pair, _ := getPair(rt, idx)
i.pairResults[pair] = successPairResult(successAmt)
}
}
// getPair returns a node pair from the route and the amount passed between that
// pair.
func getPair(rt *mcRoute, channelIdx int) (DirectedNodePair,

63
routing/result_interpretation_test.go
View file

@ -96,13 +96,17 @@ var (
AmtToForward: 99,
},
{
PubKeyBytes: hops[2],
AmtToForward: 95,
PubKeyBytes: hops[2],
// Intermediate blinded hops don't have an
// amount set.
AmtToForward: 0,
BlindingPoint: genTestPubKey(),
},
{
PubKeyBytes: hops[3],
AmtToForward: 88,
PubKeyBytes: hops[3],
// Intermediate blinded hops don't have an
// amount set.
AmtToForward: 0,
},
{
PubKeyBytes: hops[4],
@ -122,8 +126,10 @@ var (
AmtToForward: 99,
},
{
PubKeyBytes: hops[2],
AmtToForward: 95,
PubKeyBytes: hops[2],
// Intermediate blinded hops don't have an
// amount set.
AmtToForward: 0,
BlindingPoint: genTestPubKey(),
},
{
@ -140,13 +146,17 @@ var (
TotalAmount: 100,
Hops: []*route.Hop{
{
PubKeyBytes: hops[1],
AmtToForward: 90,
PubKeyBytes: hops[1],
// Intermediate blinded hops don't have an
// amount set.
AmtToForward: 0,
BlindingPoint: genTestPubKey(),
},
{
PubKeyBytes: hops[2],
AmtToForward: 75,
PubKeyBytes: hops[2],
// Intermediate blinded hops don't have an
// amount set.
AmtToForward: 0,
},
{
PubKeyBytes: hops[3],
@ -552,7 +562,12 @@ var resultTestCases = []resultTestCase{
pairResults: map[DirectedNodePair]pairResult{
getTestPair(0, 1): successPairResult(100),
getTestPair(1, 2): successPairResult(99),
getTestPair(3, 4): failPairResult(88),
// The amount for the last hop is always the
// receiver amount because the amount to forward
// is always set to 0 for intermediate blinded
// hops.
getTestPair(3, 4): failPairResult(77),
},
},
},
@ -567,7 +582,12 @@ var resultTestCases = []resultTestCase{
expectedResult: &interpretedResult{
pairResults: map[DirectedNodePair]pairResult{
getTestPair(0, 1): successPairResult(100),
getTestPair(2, 3): failPairResult(75),
// The amount for the last hop is always the
// receiver amount because the amount to forward
// is always set to 0 for intermediate blinded
// hops.
getTestPair(2, 3): failPairResult(58),
},
},
},
@ -682,6 +702,25 @@ var resultTestCases = []resultTestCase{
finalFailureReason: &reasonError,
},
},
// Test a multi-hop blinded route and that in a success case the amounts
// for the blinded route part are correctly set to the receiver amount.
{
name: "blinded multi-hop success",
route: blindedMultiToIntroduction,
success: true,
expectedResult: &interpretedResult{
pairResults: map[DirectedNodePair]pairResult{
getTestPair(0, 1): successPairResult(100),
// For the route blinded part of the route the
// success amount is determined by the receiver
// amount because the intermediate blinded hops
// set the forwarded amount to 0.
getTestPair(1, 2): successPairResult(58),
getTestPair(2, 3): successPairResult(58),
},
},
},
}
// TestResultInterpretation executes a list of test cases that test the result