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https://github.com/lightningnetwork/lnd.git
synced 2025-01-19 05:45:21 +01:00
lnwallet: introduce GetDustSum method to calculate worst-case dust sum
It over-estimates the local or remote commitment's dust sum by counting all updates in both updateLogs that are dust using the trimmed-to-dust mechanism if applicable. The over-estimation is done because ensuring an accurate counting is a trade-off between code simplicity and accuracy.
This commit is contained in:
eugene
parent
34cb9357ee
commit
7d16e58b5c
@ -615,7 +615,7 @@ func (c *commitment) populateHtlcIndexes(chanType channeldb.ChannelType,
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// populateIndex is a helper function that populates the necessary
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// indexes within the commitment view for a particular HTLC.
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populateIndex := func(htlc *PaymentDescriptor, incoming bool) error {
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isDust := htlcIsDust(
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isDust := HtlcIsDust(
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chanType, incoming, c.isOurs, c.feePerKw,
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htlc.Amount.ToSatoshis(), c.dustLimit,
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)
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@ -792,7 +792,7 @@ func (lc *LightningChannel) diskHtlcToPayDesc(feeRate chainfee.SatPerKWeight,
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// generate them in order to locate the outputs within the commitment
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// transaction. As we'll mark dust with a special output index in the
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// on-disk state snapshot.
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isDustLocal := htlcIsDust(
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isDustLocal := HtlcIsDust(
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chanType, htlc.Incoming, true, feeRate,
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htlc.Amt.ToSatoshis(), lc.channelState.LocalChanCfg.DustLimit,
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)
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@ -805,7 +805,7 @@ func (lc *LightningChannel) diskHtlcToPayDesc(feeRate chainfee.SatPerKWeight,
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return pd, err
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}
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}
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isDustRemote := htlcIsDust(
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isDustRemote := HtlcIsDust(
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chanType, htlc.Incoming, false, feeRate,
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htlc.Amt.ToSatoshis(), lc.channelState.RemoteChanCfg.DustLimit,
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)
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@ -1436,7 +1436,7 @@ func (lc *LightningChannel) logUpdateToPayDesc(logUpdate *channeldb.LogUpdate,
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pd.OnionBlob = make([]byte, len(wireMsg.OnionBlob))
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copy(pd.OnionBlob[:], wireMsg.OnionBlob[:])
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isDustRemote := htlcIsDust(
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isDustRemote := HtlcIsDust(
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lc.channelState.ChanType, false, false, feeRate,
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wireMsg.Amount.ToSatoshis(), remoteDustLimit,
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)
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@ -2401,7 +2401,7 @@ func NewBreachRetribution(chanState *channeldb.OpenChannel, stateNum uint64,
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for _, htlc := range revokedSnapshot.Htlcs {
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// If the HTLC is dust, then we'll skip it as it doesn't have
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// an output on the commitment transaction.
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if htlcIsDust(
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if HtlcIsDust(
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chanState.ChanType, htlc.Incoming, false,
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chainfee.SatPerKWeight(revokedSnapshot.FeePerKw),
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htlc.Amt.ToSatoshis(), chanState.RemoteChanCfg.DustLimit,
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@ -2473,13 +2473,13 @@ func NewBreachRetribution(chanState *channeldb.OpenChannel, stateNum uint64,
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}, nil
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}
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// htlcIsDust determines if an HTLC output is dust or not depending on two
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// HtlcIsDust determines if an HTLC output is dust or not depending on two
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// bits: if the HTLC is incoming and if the HTLC will be placed on our
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// commitment transaction, or theirs. These two pieces of information are
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// require as we currently used second-level HTLC transactions as off-chain
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// covenants. Depending on the two bits, we'll either be using a timeout or
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// success transaction which have different weights.
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func htlcIsDust(chanType channeldb.ChannelType,
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func HtlcIsDust(chanType channeldb.ChannelType,
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incoming, ourCommit bool, feePerKw chainfee.SatPerKWeight,
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htlcAmt, dustLimit btcutil.Amount) bool {
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@ -2995,7 +2995,7 @@ func genRemoteHtlcSigJobs(keyRing *CommitmentKeyRing,
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// dust output after taking into account second-level HTLC fees, then a
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// sigJob will be generated and appended to the current batch.
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for _, htlc := range remoteCommitView.incomingHTLCs {
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if htlcIsDust(
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if HtlcIsDust(
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chanType, true, false, feePerKw,
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htlc.Amount.ToSatoshis(), dustLimit,
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) {
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@ -3049,7 +3049,7 @@ func genRemoteHtlcSigJobs(keyRing *CommitmentKeyRing,
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sigBatch = append(sigBatch, sigJob)
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}
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for _, htlc := range remoteCommitView.outgoingHTLCs {
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if htlcIsDust(
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if HtlcIsDust(
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chanType, false, false, feePerKw,
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htlc.Amount.ToSatoshis(), dustLimit,
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) {
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@ -4040,7 +4040,7 @@ func (lc *LightningChannel) computeView(view *htlcView, remoteChain bool,
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// weight, needed to calculate the transaction fee.
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var totalHtlcWeight int64
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for _, htlc := range filteredHTLCView.ourUpdates {
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if htlcIsDust(
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if HtlcIsDust(
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lc.channelState.ChanType, false, !remoteChain,
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feePerKw, htlc.Amount.ToSatoshis(), dustLimit,
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) {
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@ -4050,7 +4050,7 @@ func (lc *LightningChannel) computeView(view *htlcView, remoteChain bool,
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totalHtlcWeight += input.HTLCWeight
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}
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for _, htlc := range filteredHTLCView.theirUpdates {
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if htlcIsDust(
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if HtlcIsDust(
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lc.channelState.ChanType, true, !remoteChain,
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feePerKw, htlc.Amount.ToSatoshis(), dustLimit,
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) {
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@ -4976,6 +4976,67 @@ func (lc *LightningChannel) AddHTLC(htlc *lnwire.UpdateAddHTLC,
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return pd.HtlcIndex, nil
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}
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// GetDustSum takes in a boolean that determines which commitment to evaluate
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// the dust sum on. The return value is the sum of dust on the desired
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// commitment tx.
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//
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// NOTE: This over-estimates the dust exposure.
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func (lc *LightningChannel) GetDustSum(remote bool) lnwire.MilliSatoshi {
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lc.RLock()
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defer lc.RUnlock()
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var dustSum lnwire.MilliSatoshi
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dustLimit := lc.channelState.LocalChanCfg.DustLimit
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commit := lc.channelState.LocalCommitment
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if remote {
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// Calculate dust sum on the remote's commitment.
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dustLimit = lc.channelState.RemoteChanCfg.DustLimit
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commit = lc.channelState.RemoteCommitment
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}
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chanType := lc.channelState.ChanType
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feeRate := chainfee.SatPerKWeight(commit.FeePerKw)
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// Grab all of our HTLCs and evaluate against the dust limit.
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for e := lc.localUpdateLog.Front(); e != nil; e = e.Next() {
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pd := e.Value.(*PaymentDescriptor)
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if pd.EntryType != Add {
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continue
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}
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amt := pd.Amount.ToSatoshis()
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// If the satoshi amount is under the dust limit, add the msat
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// amount to the dust sum.
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if HtlcIsDust(
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chanType, false, !remote, feeRate, amt, dustLimit,
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) {
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dustSum += pd.Amount
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}
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}
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// Grab all of their HTLCs and evaluate against the dust limit.
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for e := lc.remoteUpdateLog.Front(); e != nil; e = e.Next() {
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pd := e.Value.(*PaymentDescriptor)
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if pd.EntryType != Add {
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continue
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}
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amt := pd.Amount.ToSatoshis()
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// If the satoshi amount is under the dust limit, add the msat
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// amount to the dust sum.
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if HtlcIsDust(
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chanType, true, !remote, feeRate, amt, dustLimit,
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) {
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dustSum += pd.Amount
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}
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}
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return dustSum
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}
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// MayAddOutgoingHtlc validates whether we can add an outgoing htlc to this
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// channel. We don't have a value or circuit for this htlc, because we just
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// want to test that we have slots for a potential htlc so we use a "mock"
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@ -6056,7 +6117,7 @@ func extractHtlcResolutions(feePerKw chainfee.SatPerKWeight, ourCommit bool,
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// We'll skip any HTLC's which were dust on the commitment
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// transaction, as these don't have a corresponding output
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// within the commitment transaction.
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if htlcIsDust(
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if HtlcIsDust(
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chanType, htlc.Incoming, ourCommit, feePerKw,
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htlc.Amt.ToSatoshis(), dustLimit,
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) {
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@ -9816,3 +9816,178 @@ func assertCleanOrDirty(clean bool, alice, bob *LightningChannel,
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require.False(t, alice.IsChannelClean())
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require.False(t, bob.IsChannelClean())
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}
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// TestChannelGetDustSum tests that we correctly calculate the channel's dust
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// sum for the local and remote commitments.
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func TestChannelGetDustSum(t *testing.T) {
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t.Run("dust sum tweakless", func(t *testing.T) {
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testGetDustSum(t, channeldb.SingleFunderTweaklessBit)
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})
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t.Run("dust sum anchors zero htlc fee", func(t *testing.T) {
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testGetDustSum(t, channeldb.SingleFunderTweaklessBit|
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channeldb.AnchorOutputsBit|
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channeldb.ZeroHtlcTxFeeBit,
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)
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})
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}
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func testGetDustSum(t *testing.T, chantype channeldb.ChannelType) {
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t.Parallel()
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// This makes a channel with Alice's dust limit set to 200sats and
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// Bob's dust limit set to 1300sats.
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aliceChannel, bobChannel, cleanUp, err := CreateTestChannels(chantype)
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require.NoError(t, err)
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defer cleanUp()
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// Use a function closure to assert the dust sum for a passed channel's
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// local and remote commitments match the expected values.
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checkDust := func(c *LightningChannel, expLocal,
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expRemote lnwire.MilliSatoshi) {
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localDustSum := c.GetDustSum(false)
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require.Equal(t, expLocal, localDustSum)
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remoteDustSum := c.GetDustSum(true)
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require.Equal(t, expRemote, remoteDustSum)
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}
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// We'll lower the fee from 6000sats/kWU to 253sats/kWU for our test.
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fee := chainfee.SatPerKWeight(253)
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err = aliceChannel.UpdateFee(fee)
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require.NoError(t, err)
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err = bobChannel.ReceiveUpdateFee(fee)
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require.NoError(t, err)
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err = ForceStateTransition(aliceChannel, bobChannel)
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require.NoError(t, err)
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// Create an HTLC that Bob will send to Alice which is above Alice's
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// dust limit and below Bob's dust limit. This takes into account dust
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// trimming for non-zero-fee channels.
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htlc1Amt := lnwire.MilliSatoshi(700_000)
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htlc1, preimage1 := createHTLC(0, htlc1Amt)
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_, err = bobChannel.AddHTLC(htlc1, nil)
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require.NoError(t, err)
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_, err = aliceChannel.ReceiveHTLC(htlc1)
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require.NoError(t, err)
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// Assert that GetDustSum from Alice's perspective does not consider
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// the HTLC dust on her commitment, but does on Bob's commitment.
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checkDust(aliceChannel, lnwire.MilliSatoshi(0), htlc1Amt)
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// Assert that GetDustSum from Bob's perspective results in the same
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// conditions above holding.
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checkDust(bobChannel, htlc1Amt, lnwire.MilliSatoshi(0))
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// Forcing a state transition to occur should not change the dust sum.
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err = ForceStateTransition(bobChannel, aliceChannel)
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require.NoError(t, err)
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checkDust(aliceChannel, lnwire.MilliSatoshi(0), htlc1Amt)
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checkDust(bobChannel, htlc1Amt, lnwire.MilliSatoshi(0))
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// Settling the HTLC back from Alice to Bob should not change the dust
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// sum because the HTLC is counted until it's removed from the update
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// logs via compactLogs.
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err = aliceChannel.SettleHTLC(preimage1, uint64(0), nil, nil, nil)
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require.NoError(t, err)
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err = bobChannel.ReceiveHTLCSettle(preimage1, uint64(0))
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require.NoError(t, err)
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checkDust(aliceChannel, lnwire.MilliSatoshi(0), htlc1Amt)
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checkDust(bobChannel, htlc1Amt, lnwire.MilliSatoshi(0))
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// Forcing a state transition will remove the HTLC in-memory for Bob
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// since ReceiveRevocation is called which calls compactLogs. Bob
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// should have a zero dust sum at this point. Alice will see Bob as
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// having the original dust sum since compactLogs hasn't been called.
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err = ForceStateTransition(aliceChannel, bobChannel)
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require.NoError(t, err)
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checkDust(aliceChannel, lnwire.MilliSatoshi(0), htlc1Amt)
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checkDust(bobChannel, lnwire.MilliSatoshi(0), lnwire.MilliSatoshi(0))
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// Alice now sends an HTLC of 100sats, which is below both sides' dust
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// limits.
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htlc2Amt := lnwire.MilliSatoshi(100_000)
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htlc2, _ := createHTLC(0, htlc2Amt)
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_, err = aliceChannel.AddHTLC(htlc2, nil)
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require.NoError(t, err)
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_, err = bobChannel.ReceiveHTLC(htlc2)
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require.NoError(t, err)
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// Assert that GetDustSum from Alice's perspective includes the new
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// HTLC as dust on both commitments.
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checkDust(aliceChannel, htlc2Amt, htlc1Amt+htlc2Amt)
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// Assert that GetDustSum from Bob's perspective also includes the HTLC
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// on both commitments.
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checkDust(bobChannel, htlc2Amt, htlc2Amt)
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// Alice signs for this HTLC and neither perspective should change.
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aliceSig, aliceHtlcSigs, _, err := aliceChannel.SignNextCommitment()
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require.NoError(t, err)
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err = bobChannel.ReceiveNewCommitment(aliceSig, aliceHtlcSigs)
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require.NoError(t, err)
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checkDust(aliceChannel, htlc2Amt, htlc1Amt+htlc2Amt)
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checkDust(bobChannel, htlc2Amt, htlc2Amt)
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// Bob now sends a revocation for his prior commitment, and this should
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// change Alice's perspective to no longer include the first HTLC as
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// dust.
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bobRevocation, _, err := bobChannel.RevokeCurrentCommitment()
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require.NoError(t, err)
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_, _, _, _, err = aliceChannel.ReceiveRevocation(bobRevocation)
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require.NoError(t, err)
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checkDust(aliceChannel, htlc2Amt, htlc2Amt)
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checkDust(bobChannel, htlc2Amt, htlc2Amt)
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// The rest of the dance is completed and neither perspective should
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// change.
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bobSig, bobHtlcSigs, _, err := bobChannel.SignNextCommitment()
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require.NoError(t, err)
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err = aliceChannel.ReceiveNewCommitment(bobSig, bobHtlcSigs)
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require.NoError(t, err)
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aliceRevocation, _, err := aliceChannel.RevokeCurrentCommitment()
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require.NoError(t, err)
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_, _, _, _, err = bobChannel.ReceiveRevocation(aliceRevocation)
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require.NoError(t, err)
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checkDust(aliceChannel, htlc2Amt, htlc2Amt)
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checkDust(bobChannel, htlc2Amt, htlc2Amt)
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// We'll now assert that if Alice sends an HTLC above her dust limit
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// and then updates the fee of the channel to trigger the trimmed to
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// dust mechanism, Alice will count this HTLC in the dust sum for her
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// commitment in the non-zero-fee case.
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htlc3Amt := lnwire.MilliSatoshi(400_000)
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htlc3, _ := createHTLC(1, htlc3Amt)
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_, err = aliceChannel.AddHTLC(htlc3, nil)
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require.NoError(t, err)
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_, err = bobChannel.ReceiveHTLC(htlc3)
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require.NoError(t, err)
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// Assert that this new HTLC is not counted on Alice's local commitment
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// in the dust sum. Bob's commitment should count it.
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checkDust(aliceChannel, htlc2Amt, htlc2Amt+htlc3Amt)
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checkDust(bobChannel, htlc2Amt+htlc3Amt, htlc2Amt)
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// Alice will now send UpdateFee with a large feerate and neither
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// perspective should change.
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fee = chainfee.SatPerKWeight(50_000)
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err = aliceChannel.UpdateFee(fee)
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require.NoError(t, err)
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err = bobChannel.ReceiveUpdateFee(fee)
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require.NoError(t, err)
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checkDust(aliceChannel, htlc2Amt, htlc2Amt+htlc3Amt)
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checkDust(bobChannel, htlc2Amt+htlc3Amt, htlc2Amt)
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// Forcing a state transition should change in the non-zero-fee case.
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err = ForceStateTransition(aliceChannel, bobChannel)
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require.NoError(t, err)
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if chantype.ZeroHtlcTxFee() {
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checkDust(aliceChannel, htlc2Amt, htlc2Amt+htlc3Amt)
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checkDust(bobChannel, htlc2Amt+htlc3Amt, htlc2Amt)
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} else {
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checkDust(aliceChannel, htlc2Amt+htlc3Amt, htlc2Amt+htlc3Amt)
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checkDust(bobChannel, htlc2Amt+htlc3Amt, htlc2Amt+htlc3Amt)
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}
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}
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@ -440,7 +440,7 @@ func (cb *CommitmentBuilder) createUnsignedCommitmentTx(ourBalance,
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numHTLCs := int64(0)
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for _, htlc := range filteredHTLCView.ourUpdates {
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if htlcIsDust(
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if HtlcIsDust(
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cb.chanState.ChanType, false, isOurs, feePerKw,
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htlc.Amount.ToSatoshis(), dustLimit,
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) {
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@ -450,7 +450,7 @@ func (cb *CommitmentBuilder) createUnsignedCommitmentTx(ourBalance,
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numHTLCs++
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}
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for _, htlc := range filteredHTLCView.theirUpdates {
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if htlcIsDust(
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if HtlcIsDust(
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cb.chanState.ChanType, true, isOurs, feePerKw,
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htlc.Amount.ToSatoshis(), dustLimit,
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) {
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@ -529,7 +529,7 @@ func (cb *CommitmentBuilder) createUnsignedCommitmentTx(ourBalance,
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// purposes of sorting.
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cltvs := make([]uint32, len(commitTx.TxOut))
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for _, htlc := range filteredHTLCView.ourUpdates {
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if htlcIsDust(
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if HtlcIsDust(
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cb.chanState.ChanType, false, isOurs, feePerKw,
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htlc.Amount.ToSatoshis(), dustLimit,
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) {
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@ -546,7 +546,7 @@ func (cb *CommitmentBuilder) createUnsignedCommitmentTx(ourBalance,
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cltvs = append(cltvs, htlc.Timeout)
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}
|
||||
for _, htlc := range filteredHTLCView.theirUpdates {
|
||||
if htlcIsDust(
|
||||
if HtlcIsDust(
|
||||
cb.chanState.ChanType, true, isOurs, feePerKw,
|
||||
htlc.Amount.ToSatoshis(), dustLimit,
|
||||
) {
|
||||
|
||||
@ -93,6 +93,9 @@ var (
|
||||
0xc5, 0x6c, 0xbb, 0xac, 0x46, 0x22, 0x08, 0x22,
|
||||
0x21, 0xa8, 0x76, 0x8d, 0x1d, 0x09,
|
||||
}
|
||||
|
||||
aliceDustLimit = btcutil.Amount(200)
|
||||
bobDustLimit = btcutil.Amount(1300)
|
||||
)
|
||||
|
||||
// CreateTestChannels creates to fully populated channels to be used within
|
||||
@ -112,8 +115,6 @@ func CreateTestChannels(chanType channeldb.ChannelType) (
|
||||
}
|
||||
|
||||
channelBal := channelCapacity / 2
|
||||
aliceDustLimit := btcutil.Amount(200)
|
||||
bobDustLimit := btcutil.Amount(1300)
|
||||
csvTimeoutAlice := uint32(5)
|
||||
csvTimeoutBob := uint32(4)
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user