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Merge pull request #3691 from halseth/link-bandwitch-amt-aware

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lnwallet: Make available balance HTLC fee aware
This commit is contained in:
Johan T. Halseth 2020-02-20 17:56:20 +01:00 committed by GitHub
commit 5d5069c477
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4 changed files with 484 additions and 53 deletions
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17
htlcswitch/link.go
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@ -2163,26 +2163,21 @@ func (l *channelLink) ChanID() lnwire.ChannelID {
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) Bandwidth() lnwire.MilliSatoshi {
// Get the balance available on the channel for new HTLCs. This takes
// the channel reserve into account so HTLCs up to this value won't
// violate it.
channelBandwidth := l.channel.AvailableBalance()
overflowBandwidth := l.overflowQueue.TotalHtlcAmount()
// To compute the total bandwidth, we'll take the current available
// bandwidth, then subtract the overflow bandwidth as we'll eventually
// also need to evaluate those HTLC's once space on the commitment
// transaction is free.
linkBandwidth := channelBandwidth - overflowBandwidth
// If the channel reserve is greater than the total available balance
// of the link, just return 0.
reserve := lnwire.NewMSatFromSatoshis(l.channel.LocalChanReserve())
if linkBandwidth < reserve {
overflowBandwidth := l.overflowQueue.TotalHtlcAmount()
if channelBandwidth < overflowBandwidth {
return 0
}
// Else the amount that is available to flow through the link at this
// point is the available balance minus the reserve amount we are
// required to keep as collateral.
return linkBandwidth - reserve
return channelBandwidth - overflowBandwidth
}
// AttachMailBox updates the current mailbox used by this link, and hooks up

23
htlcswitch/link_test.go
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@ -1983,8 +1983,11 @@ func TestChannelLinkBandwidthConsistency(t *testing.T) {
)
// The starting bandwidth of the channel should be exactly the amount
// that we created the channel between her and Bob.
expectedBandwidth := lnwire.NewMSatFromSatoshis(chanAmt - defaultCommitFee)
// that we created the channel between her and Bob, minus the
// commitment fee and fee for adding an additional HTLC.
expectedBandwidth := lnwire.NewMSatFromSatoshis(
chanAmt-defaultCommitFee,
) - htlcFee
assertLinkBandwidth(t, aliceLink, expectedBandwidth)
// Next, we'll create an HTLC worth 1 BTC, and send it into the link as
@ -2657,8 +2660,10 @@ func TestChannelLinkTrimCircuitsPending(t *testing.T) {
// The starting bandwidth of the channel should be exactly the amount
// that we created the channel between her and Bob, minus the commitment
// fee.
expectedBandwidth := lnwire.NewMSatFromSatoshis(chanAmt - defaultCommitFee)
// fee and fee of adding an HTLC.
expectedBandwidth := lnwire.NewMSatFromSatoshis(
chanAmt-defaultCommitFee,
) - htlcFee
assertLinkBandwidth(t, alice.link, expectedBandwidth)
// Capture Alice's starting bandwidth to perform later, relative
@ -2936,8 +2941,10 @@ func TestChannelLinkTrimCircuitsNoCommit(t *testing.T) {
// The starting bandwidth of the channel should be exactly the amount
// that we created the channel between her and Bob, minus the commitment
// fee.
expectedBandwidth := lnwire.NewMSatFromSatoshis(chanAmt - defaultCommitFee)
// fee and fee for adding an additional HTLC.
expectedBandwidth := lnwire.NewMSatFromSatoshis(
chanAmt-defaultCommitFee,
) - htlcFee
assertLinkBandwidth(t, alice.link, expectedBandwidth)
// Capture Alice's starting bandwidth to perform later, relative
@ -3192,9 +3199,9 @@ func TestChannelLinkBandwidthChanReserve(t *testing.T) {
// The starting bandwidth of the channel should be exactly the amount
// that we created the channel between her and Bob, minus the channel
// reserve.
// reserve, commitment fee and fee for adding an additional HTLC.
expectedBandwidth := lnwire.NewMSatFromSatoshis(
chanAmt - defaultCommitFee - chanReserve)
chanAmt-defaultCommitFee-chanReserve) - htlcFee
assertLinkBandwidth(t, aliceLink, expectedBandwidth)
// Next, we'll create an HTLC worth 3 BTC, and send it into the link as

199
lnwallet/channel.go
View File

@ -3103,12 +3103,13 @@ func (lc *LightningChannel) getUnsignedAckedUpdates() []channeldb.LogUpdate {
// validateCommitmentSanity is used to validate the current state of the
// commitment transaction in terms of the ChannelConstraints that we and our
// remote peer agreed upon during the funding workflow. The predictAdded
// parameter should be set to a valid PaymentDescriptor if we are validating
// in the state when adding a new HTLC, or nil otherwise.
// remote peer agreed upon during the funding workflow. The
// predict[Our|Their]Add should parameters should be set to a valid
// PaymentDescriptor if we are validating in the state when adding a new HTLC,
// or nil otherwise.
func (lc *LightningChannel) validateCommitmentSanity(theirLogCounter,
ourLogCounter uint64, remoteChain bool,
predictAdded *PaymentDescriptor) error {
predictOurAdd, predictTheirAdd *PaymentDescriptor) error {
// Fetch all updates not committed.
view := lc.fetchHTLCView(theirLogCounter, ourLogCounter)
@ -3116,14 +3117,11 @@ func (lc *LightningChannel) validateCommitmentSanity(theirLogCounter,
// If we are checking if we can add a new HTLC, we add this to the
// appropriate update log, in order to validate the sanity of the
// commitment resulting from _actually adding_ this HTLC to the state.
if predictAdded != nil {
// If the remoteChain bool is true, add to ourUpdates.
if remoteChain {
view.ourUpdates = append(view.ourUpdates, predictAdded)
} else {
// Else add to theirUpdates.
view.theirUpdates = append(view.theirUpdates, predictAdded)
}
if predictOurAdd != nil {
view.ourUpdates = append(view.ourUpdates, predictOurAdd)
}
if predictTheirAdd != nil {
view.theirUpdates = append(view.theirUpdates, predictTheirAdd)
}
commitChain := lc.localCommitChain
@ -3296,7 +3294,7 @@ func (lc *LightningChannel) SignNextCommitment() (lnwire.Sig, []lnwire.Sig, []ch
// party set up when we initially set up the channel. If we are, then
// we'll abort this state transition.
err := lc.validateCommitmentSanity(
remoteACKedIndex, lc.localUpdateLog.logIndex, true, nil,
remoteACKedIndex, lc.localUpdateLog.logIndex, true, nil, nil,
)
if err != nil {
return sig, htlcSigs, nil, err
@ -4050,7 +4048,7 @@ func (lc *LightningChannel) ReceiveNewCommitment(commitSig lnwire.Sig,
// the constraints we specified during initial channel setup. If not,
// then we'll abort the channel as they've violated our constraints.
err := lc.validateCommitmentSanity(
lc.remoteUpdateLog.logIndex, localACKedIndex, false, nil,
lc.remoteUpdateLog.logIndex, localACKedIndex, false, nil, nil,
)
if err != nil {
return err
@ -4625,6 +4623,12 @@ func (lc *LightningChannel) InitNextRevocation(revKey *btcec.PublicKey) error {
// The additional openKey argument corresponds to the incoming CircuitKey of the
// committed circuit for this HTLC. This value should never be nil.
//
// Note that AddHTLC doesn't reserve the HTLC fee for future payment (like
// AvailableBalance does), so one could get into the "stuck channel" state by
// sending dust HTLCs.
// TODO(halseth): fix this either by using additional reserve, or better commit
// format. See https://github.com/lightningnetwork/lightning-rfc/issues/728
//
// NOTE: It is okay for sourceRef to be nil when unit testing the wallet.
func (lc *LightningChannel) AddHTLC(htlc *lnwire.UpdateAddHTLC,
openKey *channeldb.CircuitKey) (uint64, error) {
@ -4644,10 +4648,26 @@ func (lc *LightningChannel) AddHTLC(htlc *lnwire.UpdateAddHTLC,
}
// Make sure adding this HTLC won't violate any of the constraints we
// must keep on our commitment transaction.
// must keep on the commitment transactions.
remoteACKedIndex := lc.localCommitChain.tail().theirMessageIndex
// First we'll check whether this HTLC can be added to the remote
// commitment transaction without violation any of the constraints.
err := lc.validateCommitmentSanity(
remoteACKedIndex, lc.localUpdateLog.logIndex, true, pd,
remoteACKedIndex, lc.localUpdateLog.logIndex, true, pd, nil,
)
if err != nil {
return 0, err
}
// We must also check whether it can be added to our own commitment
// transaction, or the remote node will refuse to sign. This is not
// totally bullet proof, as the remote might be adding updates
// concurrently, but if we fail this check there is for sure not
// possible for us to add the HTLC.
err = lc.validateCommitmentSanity(
lc.remoteUpdateLog.logIndex, lc.localUpdateLog.logIndex,
false, pd, nil,
)
if err != nil {
return 0, err
@ -4685,7 +4705,7 @@ func (lc *LightningChannel) ReceiveHTLC(htlc *lnwire.UpdateAddHTLC) (uint64, err
// Clamp down on the number of HTLC's we can receive by checking the
// commitment sanity.
err := lc.validateCommitmentSanity(
lc.remoteUpdateLog.logIndex, localACKedIndex, false, pd,
lc.remoteUpdateLog.logIndex, localACKedIndex, false, nil, pd,
)
if err != nil {
return 0, err
@ -5983,11 +6003,14 @@ func (lc *LightningChannel) CompleteCooperativeClose(localSig, remoteSig []byte,
return closeTx, ourBalance, nil
}
// AvailableBalance returns the current available balance within the channel.
// By available balance, we mean that if at this very instance s new commitment
// were to be created which evals all the log entries, what would our available
// balance me. This method is useful when deciding if a given channel can
// accept an HTLC in the multi-hop forwarding scenario.
// AvailableBalance returns the current balance available for sending within
// the channel. By available balance, we mean that if at this very instance a
// new commitment were to be created which evals all the log entries, what
// would our available balance for adding an additional HTLC be. It takes into
// account the fee that must be paid for adding this HTLC (if we're the
// initiator), and that we cannot spend from the channel reserve. This method
// is useful when deciding if a given channel can accept an HTLC in the
// multi-hop forwarding scenario.
func (lc *LightningChannel) AvailableBalance() lnwire.MilliSatoshi {
lc.RLock()
defer lc.RUnlock()
@ -6007,19 +6030,132 @@ func (lc *LightningChannel) availableBalance() (lnwire.MilliSatoshi, int64) {
htlcView := lc.fetchHTLCView(remoteACKedIndex,
lc.localUpdateLog.logIndex)
// Then compute our current balance for that view.
ourBalance, _, commitWeight, filteredView, err :=
lc.computeView(htlcView, false, false)
// Calculate our available balance from our local commitment.
// TODO(halseth): could reuse parts validateCommitmentSanity to do this
// balance calculation, as most of the logic is the same.
//
// NOTE: This is not always accurate, since the remote node can always
// add updates concurrently, causing our balance to go down if we're
// the initiator, but this is a problem on the protocol level.
ourLocalCommitBalance, commitWeight := lc.availableCommitmentBalance(
htlcView, false,
)
// Do the same calculation from the remote commitment point of view.
ourRemoteCommitBalance, _ := lc.availableCommitmentBalance(
htlcView, true,
)
// Return which ever balance is lowest.
if ourRemoteCommitBalance < ourLocalCommitBalance {
return ourRemoteCommitBalance, commitWeight
}
return ourLocalCommitBalance, commitWeight
}
// availableCommitmentBalance attempts to calculate the balance we have
// available for HTLCs on the local/remote commitment given the htlcView. To
// account for sending HTLCs of different sizes, it will report the balance
// available for sending non-dust HTLCs, which will be manifested on the
// commitment, increasing the commitment fee we must pay as an initiator,
// eating into our balance. It will make sure we won't violate the channel
// reserve constraints for this amount.
func (lc *LightningChannel) availableCommitmentBalance(view *htlcView,
remoteChain bool) (lnwire.MilliSatoshi, int64) {
// Compute the current balances for this commitment. This will take
// into account HTLCs to determine the commit weight, which the
// initiator must pay the fee for.
ourBalance, theirBalance, commitWeight, filteredView, err := lc.computeView(
view, remoteChain, false,
)
if err != nil {
lc.log.Errorf("Unable to fetch available balance: %v", err)
return 0, 0
}
// If we are the channel initiator, we must remember to subtract the
// commitment fee from our available balance.
commitFee := filteredView.feePerKw.FeeForWeight(commitWeight)
// We can never spend from the channel reserve, so we'll subtract it
// from our available balance.
ourReserve := lnwire.NewMSatFromSatoshis(
lc.channelState.LocalChanCfg.ChanReserve,
)
if ourReserve <= ourBalance {
ourBalance -= ourReserve
} else {
ourBalance = 0
}
// Calculate the commitment fee in the case where we would add another
// HTLC to the commitment, as only the balance remaining after this fee
// has been paid is actually available for sending.
feePerKw := filteredView.feePerKw
htlcCommitFee := lnwire.NewMSatFromSatoshis(
feePerKw.FeeForWeight(commitWeight + input.HTLCWeight),
)
// If we are the channel initiator, we must to subtract this commitment
// fee from our available balance in order to ensure we can afford both
// the value of the HTLC and the additional commitment fee from adding
// the HTLC.
if lc.channelState.IsInitiator {
ourBalance -= lnwire.NewMSatFromSatoshis(commitFee)
// There is an edge case where our non-zero balance is lower
// than the htlcCommitFee, where we could still be sending dust
// HTLCs, but we return 0 in this case. This is to avoid
// lowering our balance even further, as this takes us into a
// bad state wehere neither we nor our channel counterparty can
// add HTLCs.
if ourBalance < htlcCommitFee {
return 0, commitWeight
}
return ourBalance - htlcCommitFee, commitWeight
}
// If we're not the initiator, we must check whether the remote has
// enough balance to pay for the fee of our HTLC. We'll start by also
// subtracting our counterparty's reserve from their balance.
theirReserve := lnwire.NewMSatFromSatoshis(
lc.channelState.RemoteChanCfg.ChanReserve,
)
if theirReserve <= theirBalance {
theirBalance -= theirReserve
} else {
theirBalance = 0
}
// We'll use the dustlimit and htlcFee to find the largest HTLC value
// that will be considered dust on the commitment.
dustlimit := lnwire.NewMSatFromSatoshis(
lc.channelState.LocalChanCfg.DustLimit,
)
// For an extra HTLC fee to be paid on our commitment, the HTLC must be
// large enough to make a non-dust HTLC timeout transaction.
htlcFee := lnwire.NewMSatFromSatoshis(
htlcTimeoutFee(feePerKw),
)
// If we are looking at the remote commitment, we must use the remote
// dust limit and the fee for adding an HTLC success transaction.
if remoteChain {
dustlimit = lnwire.NewMSatFromSatoshis(
lc.channelState.RemoteChanCfg.DustLimit,
)
htlcFee = lnwire.NewMSatFromSatoshis(
htlcSuccessFee(feePerKw),
)
}
// The HTLC output will be manifested on the commitment if it
// is non-dust after paying the HTLC fee.
nonDustHtlcAmt := dustlimit + htlcFee
// If they cannot pay the fee if we add another non-dust HTLC, we'll
// report our available balance just below the non-dust amount, to
// avoid attempting HTLCs larger than this size.
if theirBalance < htlcCommitFee && ourBalance >= nonDustHtlcAmt {
ourBalance = nonDustHtlcAmt - 1
}
return ourBalance, commitWeight
@ -6230,13 +6366,14 @@ func (lc *LightningChannel) MaxFeeRate(maxAllocation float64) chainfee.SatPerKWe
// The maximum fee depends of the available balance that can be
// committed towards fees.
balance, weight := lc.availableBalance()
commit := lc.channelState.LocalCommitment
feeBalance := float64(
balance.ToSatoshis() + lc.channelState.LocalCommitment.CommitFee,
commit.LocalBalance.ToSatoshis() + commit.CommitFee,
)
maxFee := feeBalance * maxAllocation
// Ensure the fee rate doesn't dip below the fee floor.
_, weight := lc.availableBalance()
maxFeeRate := maxFee / (float64(weight) / 1000)
return chainfee.SatPerKWeight(
math.Max(maxFeeRate, float64(chainfee.FeePerKwFloor)),

298
lnwallet/channel_test.go
View File

@ -4599,6 +4599,16 @@ func TestChanAvailableBandwidth(t *testing.T) {
}
defer cleanUp()
aliceReserve := lnwire.NewMSatFromSatoshis(
aliceChannel.channelState.LocalChanCfg.ChanReserve,
)
feeRate := chainfee.SatPerKWeight(
aliceChannel.channelState.LocalCommitment.FeePerKw,
)
htlcFee := lnwire.NewMSatFromSatoshis(
feeRate.FeeForWeight(input.HTLCWeight),
)
assertBandwidthEstimateCorrect := func(aliceInitiate bool) {
// With the HTLC's added, we'll now query the AvailableBalance
// method for the current available channel bandwidth from
@ -4625,11 +4635,15 @@ func TestChanAvailableBandwidth(t *testing.T) {
// Now, we'll obtain the current available bandwidth in Alice's
// latest commitment and compare that to the prior estimate.
aliceBalance := aliceChannel.channelState.LocalCommitment.LocalBalance
if aliceBalance != aliceAvailableBalance {
// The balance we have available for new HTLCs should be the
// current local commitment balance, minus the channel reserve
// and the fee for adding an HTLC.
expBalance := aliceBalance - aliceReserve - htlcFee
if expBalance != aliceAvailableBalance {
_, _, line, _ := runtime.Caller(1)
t.Fatalf("line: %v, incorrect balance: expected %v, "+
"got %v", line, aliceBalance,
aliceAvailableBalance)
"got %v", line, expBalance, aliceAvailableBalance)
}
}
@ -4707,6 +4721,185 @@ func TestChanAvailableBandwidth(t *testing.T) {
// TODO(roasbeef): additional tests from diff starting conditions
}
// TestChanAvailableBalanceNearHtlcFee checks that we get the expected reported
// balance when it is close to the htlc fee.
func TestChanAvailableBalanceNearHtlcFee(t *testing.T) {
t.Parallel()
// Create a test channel which will be used for the duration of this
// unittest. The channel will be funded evenly with Alice having 5 BTC,
// and Bob having 5 BTC.
aliceChannel, bobChannel, cleanUp, err := CreateTestChannels(true)
if err != nil {
t.Fatalf("unable to create test channels: %v", err)
}
defer cleanUp()
// Alice and Bob start with half the channel capacity.
aliceBalance := lnwire.NewMSatFromSatoshis(5 * btcutil.SatoshiPerBitcoin)
bobBalance := lnwire.NewMSatFromSatoshis(5 * btcutil.SatoshiPerBitcoin)
aliceReserve := lnwire.NewMSatFromSatoshis(
aliceChannel.channelState.LocalChanCfg.ChanReserve,
)
bobReserve := lnwire.NewMSatFromSatoshis(
bobChannel.channelState.LocalChanCfg.ChanReserve,
)
aliceDustlimit := lnwire.NewMSatFromSatoshis(
aliceChannel.channelState.LocalChanCfg.DustLimit,
)
feeRate := chainfee.SatPerKWeight(
aliceChannel.channelState.LocalCommitment.FeePerKw,
)
htlcFee := lnwire.NewMSatFromSatoshis(
feeRate.FeeForWeight(input.HTLCWeight),
)
commitFee := lnwire.NewMSatFromSatoshis(
aliceChannel.channelState.LocalCommitment.CommitFee,
)
htlcTimeoutFee := lnwire.NewMSatFromSatoshis(
htlcTimeoutFee(feeRate),
)
htlcSuccessFee := lnwire.NewMSatFromSatoshis(
htlcSuccessFee(feeRate),
)
// Helper method to check the current reported balance.
checkBalance := func(t *testing.T, expBalanceAlice,
expBalanceBob lnwire.MilliSatoshi) {
t.Helper()
aliceBalance := aliceChannel.AvailableBalance()
if aliceBalance != expBalanceAlice {
t.Fatalf("Expected alice balance %v, got %v",
expBalanceAlice, aliceBalance)
}
bobBalance := bobChannel.AvailableBalance()
if bobBalance != expBalanceBob {
t.Fatalf("Expected bob balance %v, got %v",
expBalanceBob, bobBalance)
}
}
// Helper method to send an HTLC from Alice to Bob, decreasing Alice's
// balance.
htlcIndex := uint64(0)
sendHtlc := func(htlcAmt lnwire.MilliSatoshi) {
t.Helper()
htlc, preImage := createHTLC(int(htlcIndex), htlcAmt)
if _, err := aliceChannel.AddHTLC(htlc, nil); err != nil {
t.Fatalf("unable to add htlc: %v", err)
}
if _, err := bobChannel.ReceiveHTLC(htlc); err != nil {
t.Fatalf("unable to recv htlc: %v", err)
}
if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
t.Fatalf("unable to complete alice's state "+
"transition: %v", err)
}
err = bobChannel.SettleHTLC(preImage, htlcIndex, nil, nil, nil)
if err != nil {
t.Fatalf("unable to settle htlc: %v", err)
}
err = aliceChannel.ReceiveHTLCSettle(preImage, htlcIndex)
if err != nil {
t.Fatalf("unable to settle htlc: %v", err)
}
if err := ForceStateTransition(aliceChannel, bobChannel); err != nil {
t.Fatalf("unable to complete alice's state "+
"transition: %v", err)
}
htlcIndex++
aliceBalance -= htlcAmt
bobBalance += htlcAmt
}
// Balance should start out equal to half the channel capacity minus
// the commitment fee Alice must pay and the channel reserve. In
// addition the HTLC fee will be subtracted fromt the balance to
// reflect that this value must be reserved for any payment above the
// dust limit.
expAliceBalance := aliceBalance - commitFee - aliceReserve - htlcFee
// Bob is not the initiator, so he will have all his balance available,
// since Alice pays for fees. Bob only need to keep his balance above
// the reserve.
expBobBalance := bobBalance - bobReserve
checkBalance(t, expAliceBalance, expBobBalance)
// Find the minumim size of a non-dust HTLC.
aliceNonDustHtlc := aliceDustlimit + htlcTimeoutFee
// Send a HTLC leaving Alice's remaining balance just enough to have
// nonDustHtlc left after paying the commit fee and htlc fee.
htlcAmt := aliceBalance - (commitFee + aliceReserve + htlcFee + aliceNonDustHtlc)
sendHtlc(htlcAmt)
// Now the real balance left will be
// nonDustHtlc+commitfee+aliceReserve+htlcfee. The available balance
// reported will just be nonDustHtlc, since the rest of the balance is
// reserved.
expAliceBalance = aliceNonDustHtlc
expBobBalance = bobBalance - bobReserve
checkBalance(t, expAliceBalance, expBobBalance)
// Send an HTLC using all but one msat of the reported balance.
htlcAmt = aliceNonDustHtlc - 1
sendHtlc(htlcAmt)
// 1 msat should be left.
expAliceBalance = 1
// Bob should still have all his balance available, since even though
// Alice cannot afford to add a non-dust HTLC, she can afford to add a
// non-dust HTLC from Bob.
expBobBalance = bobBalance - bobReserve
checkBalance(t, expAliceBalance, expBobBalance)
// Sendng the last msat.
htlcAmt = 1
sendHtlc(htlcAmt)
// No balance left.
expAliceBalance = 0
// We try to always reserve enough for the non-iniitator to be able to
// add an HTLC, hence Bob should still have all his non-reserved
// balance available.
expBobBalance = bobBalance - bobReserve
checkBalance(t, expAliceBalance, expBobBalance)
// Even though Alice has a reported balance of 0, this is because we
// try to avoid getting into the position where she cannot pay the fee
// for Bob adding another HTLC. This means she actually _has_ some
// balance left, and we now force the channel into this situation by
// sending yet another HTLC. In practice this can also happen if a fee
// update eats into Alice's balance.
htlcAmt = 1
sendHtlc(htlcAmt)
// Now Alice balance is so low that she cannot even afford to add a new
// HTLC from Bob to the commitment transaction. Bob's balance should
// reflect this, by only reporting dust amount being available. Alice
// should still report a zero balance.
// Since the dustlimit is different for the two commitments, the
// largest HTLC Bob can send that Alice can afford on both commitments
// (remember she cannot afford to pay the HTLC fee) is the largest dust
// HTLC on Alice's commitemnt, since her dust limit is lower.
bobNonDustHtlc := aliceDustlimit + htlcSuccessFee
expBobBalance = bobNonDustHtlc - 1
expAliceBalance = 0
checkBalance(t, expAliceBalance, expBobBalance)
}
// TestSignCommitmentFailNotLockedIn tests that a channel will not attempt to
// create a new state if it doesn't yet know of the next revocation point for
// the remote party.
@ -6007,6 +6200,105 @@ func TestChanReserve(t *testing.T) {
)
}
// TestChanReserveRemoteInitiator tests that the channel reserve of the
// initiator is accounted for when adding HTLCs, whether the initiator is the
// local or remote node.
func TestChanReserveRemoteInitiator(t *testing.T) {
t.Parallel()
// We start out with a channel where both parties have 5 BTC.
aliceChannel, bobChannel, cleanUp, err := CreateTestChannels(
true,
)
if err != nil {
t.Fatal(err)
}
defer cleanUp()
// Set Alice's channel reserve to be 5 BTC-commitfee. This means she
// has just enough balance to cover the comitment fee, but not enough
// to add any more HTLCs to the commitment. Although a reserve this
// high is unrealistic, a channel can easiliy get into a situation
// where the initiator cannot pay for the fee of any more HTLCs.
commitFee := aliceChannel.channelState.LocalCommitment.CommitFee
aliceMinReserve := 5*btcutil.SatoshiPerBitcoin - commitFee
aliceChannel.channelState.LocalChanCfg.ChanReserve = aliceMinReserve
bobChannel.channelState.RemoteChanCfg.ChanReserve = aliceMinReserve
// Now let Bob attempt to add an HTLC of 0.1 BTC. He has plenty of
// money available to spend, but Alice, which is the initiator, cannot
// afford any more HTLCs on the commitment transaction because that
// would take here below her channel reserve..
htlcAmt := lnwire.NewMSatFromSatoshis(0.1 * btcutil.SatoshiPerBitcoin)
htlc, _ := createHTLC(0, htlcAmt)
// Bob should refuse to add this HTLC, since he realizes it will create
// an invalid commitment.
_, err = bobChannel.AddHTLC(htlc, nil)
if err != ErrBelowChanReserve {
t.Fatalf("expected ErrBelowChanReserve, instead received: %v",
err)
}
// Of course Alice will also not have enough balance to add it herself.
_, err = aliceChannel.AddHTLC(htlc, nil)
if err != ErrBelowChanReserve {
t.Fatalf("expected ErrBelowChanReserve, instead received: %v",
err)
}
// Same for Alice, she should refuse to accept this second HTLC.
if _, err := aliceChannel.ReceiveHTLC(htlc); err != ErrBelowChanReserve {
t.Fatalf("expected ErrBelowChanReserve, instead received: %v", err)
}
}
// TestChanReserveLocalInitiatorDustHtlc tests that fee the initiator must pay
// when adding HTLCs is accounted for, even though the HTLC is considered dust
// by the remote bode.
func TestChanReserveLocalInitiatorDustHtlc(t *testing.T) {
t.Parallel()
aliceChannel, bobChannel, cleanUp, err := CreateTestChannels(
true,
)
if err != nil {
t.Fatal(err)
}
defer cleanUp()
// The amount of the HTLC should not be considered dust according to
// Alice's dust limit (200 sat), but be dust according to Bob's dust
// limit (1300 sat). It is considered dust if the amount remaining
// after paying the HTLC fee is below the dustlimit, so we choose a
// size of 500+htlcFee.
htlcSat := btcutil.Amount(500) + htlcTimeoutFee(
chainfee.SatPerKWeight(
aliceChannel.channelState.LocalCommitment.FeePerKw,
),
)
// Set Alice's channel reserve to be low enough to carry the value of
// the HTLC, but not low enough to allow the extra fee from adding the
// HTLC to the commitment.
commitFee := aliceChannel.channelState.LocalCommitment.CommitFee
aliceMinReserve := 5*btcutil.SatoshiPerBitcoin - commitFee - htlcSat
aliceChannel.channelState.LocalChanCfg.ChanReserve = aliceMinReserve
bobChannel.channelState.RemoteChanCfg.ChanReserve = aliceMinReserve
htlcDustAmt := lnwire.NewMSatFromSatoshis(htlcSat)
htlc, _ := createHTLC(0, htlcDustAmt)
// Alice should realize that the fee she must pay to add this HTLC to
// the local commitment would take her below the channel reserve.
_, err = aliceChannel.AddHTLC(htlc, nil)
if err != ErrBelowChanReserve {
t.Fatalf("expected ErrBelowChanReserve, instead received: %v", err)
}
}
// TestMinHTLC tests that the ErrBelowMinHTLC error is thrown if an HTLC is added
// that is below the minimm allowed value for HTLCs.
func TestMinHTLC(t *testing.T) {