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Apply 0-reserve to both peers #556

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merged 1 commit into from
Nov 10, 2023
Merged

Apply 0-reserve to both peers #556

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17 changes: 5 additions & 12 deletions src/commonMain/kotlin/fr/acinq/lightning/channel/Commitments.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -146,12 +146,12 @@ data class Commitment(
val fundingAmount: Satoshi = commitInput.txOut.amount

fun localChannelReserve(params: ChannelParams): Satoshi = when {
params.channelFeatures.hasFeature(Feature.ZeroReserveChannels) && !params.localParams.isInitiator -> 0.sat
params.channelFeatures.hasFeature(Feature.ZeroReserveChannels) -> 0.sat
else -> (fundingAmount / 100).max(params.remoteParams.dustLimit)
}

fun remoteChannelReserve(params: ChannelParams): Satoshi = when {
params.channelFeatures.hasFeature(Feature.ZeroReserveChannels) && params.localParams.isInitiator -> 0.sat
params.channelFeatures.hasFeature(Feature.ZeroReserveChannels) -> 0.sat
else -> (fundingAmount / 100).max(params.localParams.dustLimit)
}

Expand Down Expand Up @@ -390,14 +390,7 @@ data class Commitment(
// and it would be tricky to check if the conditions are met at signing
// (it also means that we need to check the fee of the initial commitment tx somewhere)
val fees = commitTxFee(params.localParams.dustLimit, reduced)
// TODO:
// When migrating to the dual-funded model, we removed the explicit channel reserve from LocalParams.
// For channels that were created before the splicing update, this can result in a mismatch where we think
// the channel reserve is bigger than what is actually is, and incorrectly reject the remote update_fee.
// We temporarily ignore the channel reserve to avoid unnecessary force-close.
// We should restore the correct calculation that takes the reserve into account once all users have migrated.
// val missing = reduced.toRemote.truncateToSatoshi() - remoteChannelReserve(params) - fees
val missing = reduced.toRemote.truncateToSatoshi() - fees
val missing = reduced.toRemote.truncateToSatoshi() - remoteChannelReserve(params) - fees
return if (missing < 0.sat) {
Either.Left(CannotAffordFees(params.channelId, -missing, remoteChannelReserve(params), fees))
} else {
Expand Down Expand Up @@ -515,11 +508,11 @@ data class FullCommitment(
val fundingTxId: ByteVector32 = commitInput.outPoint.txid
val fundingAmount = commitInput.txOut.amount
val localChannelReserve = when {
params.channelFeatures.hasFeature(Feature.ZeroReserveChannels) && !params.localParams.isInitiator -> 0.sat
params.channelFeatures.hasFeature(Feature.ZeroReserveChannels) -> 0.sat
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The duplication between Commitments and FullCommitments shows that there is some cleanup to do

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True, but I'm not sure how it could be cleaned up though, so I'm leaving it as-is for now.

else -> (fundingAmount / 100).max(params.remoteParams.dustLimit)
}
val remoteChannelReserve = when {
params.channelFeatures.hasFeature(Feature.ZeroReserveChannels) && params.localParams.isInitiator -> 0.sat
params.channelFeatures.hasFeature(Feature.ZeroReserveChannels) -> 0.sat
else -> (fundingAmount / 100).max(params.localParams.dustLimit)
}
}
Expand Down
18 changes: 16 additions & 2 deletions src/commonTest/kotlin/fr/acinq/lightning/channel/states/NormalTestsCommon.kt
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Expand Up @@ -429,6 +429,21 @@ class NormalTestsCommon : LightningTestSuite() {
assertEquals(alice1.commitments.changes.remoteChanges.proposed, listOf(add))
}

@Test
fun `recv UpdateAddHtlc -- zero-conf -- zero-reserve -- initiator`() {
val (alice0, bob0) = reachNormal(ChannelType.SupportedChannelType.AnchorOutputsZeroReserve, aliceFundingAmount = 10_000_000.sat, bobFundingAmount = 5_000_000.sat, alicePushAmount = 9_800_000_000.msat, zeroConf = true)
assertEquals(alice0.commitments.latest.fundingAmount, 15_000_000.sat)
assertEquals(alice0.commitments.latest.localCommit.spec.toLocal, 200_000_000.msat)
// If we applied the default 1% reserve, Alice's balance couldn't go below 150 000 sats.
// Alice still needs to pay the commit tx fees, so she cannot spend her entire balance.
val (nodes1, r, htlc) = addHtlc(160_000_000.msat, alice0, bob0)
val (alice2, bob2) = crossSign(nodes1.first, nodes1.second)
val (alice3, bob3) = fulfillHtlc(htlc.id, r, alice2, bob2)
val (bob4, alice4) = crossSign(bob3, alice3)
assertEquals(alice4.commitments.latest.localCommit.spec.toLocal, 40_000_000.msat)
assertEquals(bob4.commitments.latest.localCommit.spec.toRemote, 40_000_000.msat)
}

@Test
fun `recv UpdateAddHtlc -- unexpected id`() {
val (_, bob0) = reachNormal()
Expand Down Expand Up @@ -1419,8 +1434,7 @@ class NormalTestsCommon : LightningTestSuite() {
assertEquals(bob.commitments.copy(changes = bob.commitments.changes.copy(remoteChanges = bob.commitments.changes.remoteChanges.copy(proposed = bob.commitments.changes.remoteChanges.proposed + fee2))), bob2.commitments)
}

// TODO: restore this test once we take the reserve into account (see canReceiveFee)
@Ignore
@Test
fun `recv UpdateFee -- sender cannot afford it`() {
val (alice, bob) = reachNormal()
// We put all the balance on Bob's side, so that Alice cannot afford a feerate increase.
Expand Down
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