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htlcswitch: respect minimum relay fee

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When channels fee rates are being considered for an update, the minimum
relay fee should also be considered.
This commit is contained in:
Elle Mouton 2021-06-23 14:28:25 +02:00
parent 6712595618
commit f667683e6c
No known key found for this signature in database
GPG Key ID: D7D916376026F177
5 changed files with 317 additions and 60 deletions
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38
htlcswitch/link.go
View File

@ -4,7 +4,6 @@ import (
"bytes"
"crypto/sha256"
"fmt"
"math"
prand "math/rand"
"sync"
"sync/atomic"
@ -619,9 +618,18 @@ func (l *channelLink) sampleNetworkFee() (chainfee.SatPerKWeight, error) {
// shouldAdjustCommitFee returns true if we should update our commitment fee to
// match that of the network fee. We'll only update our commitment fee if the
// network fee is +/- 10% to our network fee.
func shouldAdjustCommitFee(netFee, chanFee chainfee.SatPerKWeight) bool {
// network fee is +/- 10% to our commitment fee or if our current commitment
// fee is below the minimum relay fee.
func shouldAdjustCommitFee(netFee, chanFee,
minRelayFee chainfee.SatPerKWeight) bool {
switch {
// If the network fee is greater than our current commitment fee and
// our current commitment fee is below the minimum relay fee then
// we should switch to it no matter if it is less than a 10% increase.
case netFee > chanFee && chanFee < minRelayFee:
return true
// If the network fee is greater than the commitment fee, then we'll
// switch to it if it's at least 10% greater than the commit fee.
case netFee > chanFee && netFee >= (chanFee+(chanFee*10)/100):
@ -1106,18 +1114,22 @@ func (l *channelLink) htlcManager() {
continue
}
// We'll check to see if we should update the fee rate
// based on our current set fee rate. We'll cap the new
// fee rate to our max fee allocation.
commitFee := l.channel.CommitFeeRate()
maxFee := l.channel.MaxFeeRate(
l.cfg.MaxFeeAllocation,
minRelayFee := l.cfg.FeeEstimator.RelayFeePerKW()
newCommitFee := l.channel.IdealCommitFeeRate(
netFee, minRelayFee,
l.cfg.MaxAnchorsCommitFeeRate,
l.cfg.MaxFeeAllocation,
)
newCommitFee := chainfee.SatPerKWeight(
math.Min(float64(netFee), float64(maxFee)),
)
if !shouldAdjustCommitFee(newCommitFee, commitFee) {
// We determine if we should adjust the commitment fee
// based on the current commitment fee, the suggested
// new commitment fee and the current minimum relay fee
// rate.
commitFee := l.channel.CommitFeeRate()
if !shouldAdjustCommitFee(
newCommitFee, commitFee, minRelayFee,
) {
continue
}

48
htlcswitch/link_test.go
View File

@ -3744,6 +3744,7 @@ func TestShouldAdjustCommitFee(t *testing.T) {
tests := []struct {
netFee chainfee.SatPerKWeight
chanFee chainfee.SatPerKWeight
minRelayFee chainfee.SatPerKWeight
shouldAdjust bool
}{
@ -3819,11 +3820,22 @@ func TestShouldAdjustCommitFee(t *testing.T) {
chanFee: 1000,
shouldAdjust: false,
},
// The network fee is higher than our commitment fee,
// hasn't yet crossed our activation threshold, but the
// current commitment fee is below the minimum relay fee and
// so the fee should be updated.
{
netFee: 1100,
chanFee: 1098,
minRelayFee: 1099,
shouldAdjust: true,
},
}
for i, test := range tests {
adjustedFee := shouldAdjustCommitFee(
test.netFee, test.chanFee,
test.netFee, test.chanFee, test.minRelayFee,
)
if adjustedFee && !test.shouldAdjust {
@ -4009,6 +4021,13 @@ func TestChannelLinkUpdateCommitFee(t *testing.T) {
{"bob", "alice", &lnwire.RevokeAndAck{}, false},
{"bob", "alice", &lnwire.CommitSig{}, false},
{"alice", "bob", &lnwire.RevokeAndAck{}, false},
// Third fee update.
{"alice", "bob", &lnwire.UpdateFee{}, false},
{"alice", "bob", &lnwire.CommitSig{}, false},
{"bob", "alice", &lnwire.RevokeAndAck{}, false},
{"bob", "alice", &lnwire.CommitSig{}, false},
{"alice", "bob", &lnwire.RevokeAndAck{}, false},
}
n.aliceServer.intersect(createInterceptorFunc("[alice] <-- [bob]",
"alice", messages, chanID, false))
@ -4025,8 +4044,8 @@ func TestChannelLinkUpdateCommitFee(t *testing.T) {
// triggerFeeUpdate is a helper closure to determine whether a fee
// update was triggered and completed properly.
triggerFeeUpdate := func(feeEstimate, newFeeRate chainfee.SatPerKWeight,
shouldUpdate bool) {
triggerFeeUpdate := func(feeEstimate, minRelayFee,
newFeeRate chainfee.SatPerKWeight, shouldUpdate bool) {
t.Helper()
@ -4046,6 +4065,13 @@ func TestChannelLinkUpdateCommitFee(t *testing.T) {
t.Fatalf("alice didn't query for the new network fee")
}
// We also send the min relay fee response to Alice.
select {
case n.feeEstimator.relayFee <- minRelayFee:
case <-time.After(time.Second * 5):
t.Fatalf("alice didn't query for the min relay fee")
}
// Record the fee rates after the links have processed the fee
// update and ensure they are correct based on whether a fee
// update should have been triggered.
@ -4071,20 +4097,28 @@ func TestChannelLinkUpdateCommitFee(t *testing.T) {
}, 10*time.Second, time.Second)
}
minRelayFee := startingFeeRate / 3
// Triggering the link to update the fee of the channel with the same
// fee rate should not send a fee update.
triggerFeeUpdate(startingFeeRate, startingFeeRate, false)
triggerFeeUpdate(startingFeeRate, minRelayFee, startingFeeRate, false)
// Triggering the link to update the fee of the channel with a much
// larger fee rate _should_ send a fee update.
newFeeRate := startingFeeRate * 3
triggerFeeUpdate(newFeeRate, newFeeRate, true)
triggerFeeUpdate(newFeeRate, minRelayFee, newFeeRate, true)
// Triggering the link to update the fee of the channel with a fee rate
// that exceeds its maximum fee allocation should result in a fee rate
// corresponding to the maximum fee allocation.
const maxFeeRate chainfee.SatPerKWeight = 207182320
triggerFeeUpdate(maxFeeRate+1, maxFeeRate, true)
const maxFeeRate chainfee.SatPerKWeight = 207180182
triggerFeeUpdate(maxFeeRate+1, minRelayFee, maxFeeRate, true)
// Triggering the link to update the fee of the channel with a fee rate
// that is below the current min relay fee rate should result in a fee
// rate corresponding to the minimum relay fee.
newFeeRate = minRelayFee / 2
triggerFeeUpdate(newFeeRate, minRelayFee, minRelayFee, true)
}
// TestChannelLinkAcceptDuplicatePayment tests that if a link receives an

9
htlcswitch/mock.go
View File

@ -71,6 +71,7 @@ func (m *mockPreimageCache) SubscribeUpdates() *contractcourt.WitnessSubscriptio
type mockFeeEstimator struct {
byteFeeIn chan chainfee.SatPerKWeight
relayFee chan chainfee.SatPerKWeight
quit chan struct{}
}
@ -78,6 +79,7 @@ type mockFeeEstimator struct {
func newMockFeeEstimator() *mockFeeEstimator {
return &mockFeeEstimator{
byteFeeIn: make(chan chainfee.SatPerKWeight),
relayFee: make(chan chainfee.SatPerKWeight),
quit: make(chan struct{}),
}
}
@ -94,7 +96,12 @@ func (m *mockFeeEstimator) EstimateFeePerKW(
}
func (m *mockFeeEstimator) RelayFeePerKW() chainfee.SatPerKWeight {
return 1e3
select {
case feeRate := <-m.relayFee:
return feeRate
case <-m.quit:
return 0
}
}
func (m *mockFeeEstimator) Start() error {

81
lnwallet/channel.go
View File

@ -6992,14 +6992,11 @@ func (lc *LightningChannel) CalcFee(feeRate chainfee.SatPerKWeight) btcutil.Amou
// MaxFeeRate returns the maximum fee rate given an allocation of the channel
// initiator's spendable balance along with the local reserve amount. This can
// be useful to determine when we should stop proposing fee updates that exceed
// our maximum allocation. We also take a fee rate cap that should be used for
// anchor type channels.
// our maximum allocation.
//
// NOTE: This should only be used for channels in which the local commitment is
// the initiator.
func (lc *LightningChannel) MaxFeeRate(maxAllocation float64,
maxAnchorFeeRate chainfee.SatPerKWeight) chainfee.SatPerKWeight {
func (lc *LightningChannel) MaxFeeRate(maxAllocation float64) chainfee.SatPerKWeight {
lc.RLock()
defer lc.RUnlock()
@ -7017,16 +7014,78 @@ func (lc *LightningChannel) MaxFeeRate(maxAllocation float64,
// Ensure the fee rate doesn't dip below the fee floor.
maxFeeRate := maxFee / (float64(weight) / 1000)
feeRate := chainfee.SatPerKWeight(
return chainfee.SatPerKWeight(
math.Max(maxFeeRate, float64(chainfee.FeePerKwFloor)),
)
// Cap anchor fee rates.
if lc.channelState.ChanType.HasAnchors() && feeRate > maxAnchorFeeRate {
return maxAnchorFeeRate
}
return feeRate
// IdealCommitFeeRate uses the current network fee, the minimum relay fee,
// maximum fee allocation and anchor channel commitment fee rate to determine
// the ideal fee to be used for the commitments of the channel.
func (lc *LightningChannel) IdealCommitFeeRate(netFeeRate, minRelayFeeRate,
maxAnchorCommitFeeRate chainfee.SatPerKWeight,
maxFeeAlloc float64) chainfee.SatPerKWeight {
// Get the maximum fee rate that we can use given our max fee allocation
// and given the local reserve balance that we must preserve.
maxFeeRate := lc.MaxFeeRate(maxFeeAlloc)
var commitFeeRate chainfee.SatPerKWeight
// If the channel has anchor outputs then cap the fee rate at the
// max anchor fee rate if that maximum is less than our max fee rate.
// Otherwise, cap the fee rate at the max fee rate.
switch lc.channelState.ChanType.HasAnchors() &&
maxFeeRate > maxAnchorCommitFeeRate {
case true:
commitFeeRate = chainfee.SatPerKWeight(
math.Min(
float64(netFeeRate),
float64(maxAnchorCommitFeeRate),
),
)
case false:
commitFeeRate = chainfee.SatPerKWeight(
math.Min(float64(netFeeRate), float64(maxFeeRate)),
)
}
if commitFeeRate >= minRelayFeeRate {
return commitFeeRate
}
// The commitment fee rate is below the minimum relay fee rate.
// If the min relay fee rate is still below the maximum fee, then use
// the minimum relay fee rate.
if minRelayFeeRate <= maxFeeRate {
return minRelayFeeRate
}
// The minimum relay fee rate is more than the ideal maximum fee rate.
// Check if it is smaller than the absolute maximum fee rate we can
// use. If it is, then we use the minimum relay fee rate and we log a
// warning to indicate that the max channel fee allocation option was
// ignored.
absoluteMaxFee := lc.MaxFeeRate(1)
if minRelayFeeRate <= absoluteMaxFee {
lc.log.Warn("Ignoring max channel fee allocation to " +
"ensure that the commitment fee is above the " +
"minimum relay fee.")
return minRelayFeeRate
}
// The absolute maximum fee rate we can pay is below the minimum
// relay fee rate. The commitment tx will not be able to propagate.
// To give the transaction the best chance, we use the absolute
// maximum fee we have available and we log an error.
lc.log.Errorf("The commitment fee rate of %s is below the current "+
"minimum relay fee rate of %s. The max fee rate of %s will be"+
"used.", commitFeeRate, minRelayFeeRate, absoluteMaxFee)
return absoluteMaxFee
}
// RemoteNextRevocation returns the channelState's RemoteNextRevocation.

197
lnwallet/channel_test.go
View File

@ -8005,12 +8005,10 @@ func TestForceCloseBorkedState(t *testing.T) {
func TestChannelMaxFeeRate(t *testing.T) {
t.Parallel()
assertMaxFeeRate := func(c *LightningChannel,
maxAlloc float64, anchorMax, expFeeRate chainfee.SatPerKWeight) {
assertMaxFeeRate := func(c *LightningChannel, maxAlloc float64,
expFeeRate chainfee.SatPerKWeight) {
t.Helper()
maxFeeRate := c.MaxFeeRate(maxAlloc, anchorMax)
maxFeeRate := c.MaxFeeRate(maxAlloc)
if maxFeeRate != expFeeRate {
t.Fatalf("expected max fee rate of %v with max "+
"allocation of %v, got %v", expFeeRate,
@ -8025,14 +8023,9 @@ func TestChannelMaxFeeRate(t *testing.T) {
// propertyTest tests that the validateFeeRate function always passes
// for the output returned by MaxFeeRate for any valid random inputs
// fed to MaxFeeRate.
propertyTest := func(c *LightningChannel) func(alloc maxAlloc,
anchorMax fee) bool {
return func(ma maxAlloc, anchorMax fee) bool {
maxFeeRate := c.MaxFeeRate(
float64(ma), chainfee.SatPerKWeight(anchorMax),
)
propertyTest := func(c *LightningChannel) func(alloc maxAlloc) bool {
return func(ma maxAlloc) bool {
maxFeeRate := c.MaxFeeRate(float64(ma))
return c.validateFeeRate(maxFeeRate) == nil
}
}
@ -8045,18 +8038,19 @@ func TestChannelMaxFeeRate(t *testing.T) {
}
defer cleanUp()
if err = quick.Check(propertyTest(aliceChannel), nil); err != nil {
if err := quick.Check(propertyTest(aliceChannel), nil); err != nil {
t.Fatal(err)
}
assertMaxFeeRate(aliceChannel, 1.0, 0, 676794154)
assertMaxFeeRate(aliceChannel, 0.001, 0, 676794)
assertMaxFeeRate(aliceChannel, 0.000001, 0, 676)
assertMaxFeeRate(aliceChannel, 0.0000001, 0, chainfee.FeePerKwFloor)
assertMaxFeeRate(aliceChannel, 1.0, 676794154)
assertMaxFeeRate(aliceChannel, 0.001, 676794)
assertMaxFeeRate(aliceChannel, 0.000001, 676)
assertMaxFeeRate(aliceChannel, 0.0000001, chainfee.FeePerKwFloor)
// Check that anchor channels are capped at their max fee rate.
anchorChannel, _, cleanUp, err := CreateTestChannels(
channeldb.SingleFunderTweaklessBit | channeldb.AnchorOutputsBit,
channeldb.SingleFunderTweaklessBit |
channeldb.AnchorOutputsBit | channeldb.ZeroHtlcTxFeeBit,
)
if err != nil {
t.Fatalf("unable to create test channels: %v", err)
@ -8069,16 +8063,167 @@ func TestChannelMaxFeeRate(t *testing.T) {
// Anchor commitments are heavier, hence will the same allocation lead
// to slightly lower fee rates.
assertMaxFeeRate(
anchorChannel, 1.0, chainfee.FeePerKwFloor,
assertMaxFeeRate(anchorChannel, 1.0, 435941555)
assertMaxFeeRate(anchorChannel, 0.001, 435941)
assertMaxFeeRate(anchorChannel, 0.000001, 435)
assertMaxFeeRate(anchorChannel, 0.0000001, chainfee.FeePerKwFloor)
}
// TestIdealCommitFeeRate tests that we correctly compute the ideal commitment
// fee of a channel given the current network fee, minimum relay fee, maximum
// fee allocation and whether the channel has anchor outputs.
func TestIdealCommitFeeRate(t *testing.T) {
t.Parallel()
assertIdealFeeRate := func(c *LightningChannel, netFee, minRelay,
maxAnchorCommit chainfee.SatPerKWeight,
maxFeeAlloc float64, expectedFeeRate chainfee.SatPerKWeight) {
feeRate := c.IdealCommitFeeRate(
netFee, minRelay, maxAnchorCommit, maxFeeAlloc,
)
if feeRate != expectedFeeRate {
t.Fatalf("expected fee rate of %v got %v",
expectedFeeRate, feeRate)
}
if err := c.validateFeeRate(feeRate); err != nil {
t.Fatalf("fee rate validation failed: %v", err)
}
}
// propertyTest tests that the validateFeeRate function always passes
// for the output returned by IdealCommitFeeRate for any valid random
// inputs fed to IdealCommitFeeRate.
propertyTest := func(c *LightningChannel) func(ma maxAlloc,
netFee, minRelayFee, maxAnchorFee fee) bool {
return func(ma maxAlloc, netFee, minRelayFee,
maxAnchorFee fee) bool {
idealFeeRate := c.IdealCommitFeeRate(
chainfee.SatPerKWeight(netFee),
chainfee.SatPerKWeight(minRelayFee),
chainfee.SatPerKWeight(maxAnchorFee),
float64(ma),
)
return c.validateFeeRate(idealFeeRate) == nil
}
}
// Test ideal fee rates for a non-anchor channel
t.Run("non-anchor-channel", func(t *testing.T) {
aliceChannel, _, cleanUp, err := CreateTestChannels(
channeldb.SingleFunderTweaklessBit,
)
if err != nil {
t.Fatalf("unable to create test channels: %v", err)
}
defer cleanUp()
err = quick.Check(propertyTest(aliceChannel), nil)
if err != nil {
t.Fatal(err)
}
// If the maximum fee is lower than the network fee and above
// the min relay fee, use the maximum fee.
assertIdealFeeRate(
aliceChannel, 700000000, 0, 0, 1.0, 676794154,
)
// If the network fee is lower than the max fee and above the
// min relay fee, use the network fee.
assertIdealFeeRate(
aliceChannel, 500000000, 0, 0, 1.0, 500000000,
)
// If the fee is below the minimum relay fee, and the min relay
// fee is less than our max fee, use the minimum relay fee.
assertIdealFeeRate(
aliceChannel, 500000000, 600000000, 0, 1.0, 600000000,
)
// The absolute maximum fee rate we can pay (ie, using a max
// allocation of 1) is still below the minimum relay fee. In
// this case, use the absolute max fee.
assertIdealFeeRate(
aliceChannel, 800000000, 700000000, 0, 0.001,
676794154,
)
})
// Test ideal fee rates for an anchor channel
t.Run("anchor-channel", func(t *testing.T) {
anchorChannel, _, cleanUp, err := CreateTestChannels(
channeldb.SingleFunderTweaklessBit |
channeldb.AnchorOutputsBit |
channeldb.ZeroHtlcTxFeeBit,
)
if err != nil {
t.Fatalf("unable to create test channels: %v", err)
}
defer cleanUp()
err = quick.Check(propertyTest(anchorChannel), nil)
if err != nil {
t.Fatal(err)
}
// Anchor commitments are heavier, hence the same allocation
// leads to slightly lower fee rates.
assertIdealFeeRate(
anchorChannel, 700000000, 0, chainfee.FeePerKwFloor,
0.1, chainfee.FeePerKwFloor,
)
// If the maximum fee is lower than the network fee, use the
// maximum fee.
assertIdealFeeRate(
anchorChannel, 700000000, 0, 1000000, 0.001, 435941,
)
assertIdealFeeRate(
anchorChannel, 700000000, 0, 700, 0.000001, 435,
)
assertIdealFeeRate(
anchorChannel, 700000000, 0, 1000000, 0.0000001,
chainfee.FeePerKwFloor,
)
assertMaxFeeRate(anchorChannel, 0.001, 1000000, 435941)
assertMaxFeeRate(anchorChannel, 0.001, 300000, 300000)
assertMaxFeeRate(anchorChannel, 0.000001, 700, 435)
assertMaxFeeRate(
anchorChannel, 0.0000001, 1000000, chainfee.FeePerKwFloor,
// If the maximum anchor commit fee rate is less than the
// maximum fee, use the max anchor commit fee since this is an
// anchor channel.
assertIdealFeeRate(
anchorChannel, 700000000, 0, 400000, 0.001, 400000,
)
// If the minimum relay fee is above the max anchor commitment
// fee rate but still below our max fee rate then use the min
// relay fee.
assertIdealFeeRate(
anchorChannel, 700000000, 400000, 300000, 0.001,
400000,
)
// If the min relay fee is above the ideal max fee rate but is
// below the max fee rate when the max fee allocation is set to
// 1, the minimum relay fee is used.
assertIdealFeeRate(
anchorChannel, 700000000, 500000, 300000, 0.001,
500000,
)
// The absolute maximum fee rate we can pay (ie, using a max
// allocation of 1) is still below the minimum relay fee. In
// this case, use the absolute max fee.
assertIdealFeeRate(
anchorChannel, 700000000, 450000000, 300000, 0.001,
435941555,
)
})
}
type maxAlloc float64