Add quiescence negotiation

src/commonMain/kotlin/fr/acinq/lightning/Features.kt

@@ -242,6 +242,13 @@ sealed class Feature {
  override val scopes: Set<FeatureScope> get() = setOf(FeatureScope.Init)
  }
 
+ @Serializable
+ object Quiescence : Feature() {
+ override val rfcName get() = "option_quiescence"
+ override val mandatory get() = 34
+ override val scopes: Set<FeatureScope> get() = setOf(FeatureScope.Init, FeatureScope.Node)
+ }
+
 }
 
 @Serializable
@@ -320,6 +327,7 @@ data class Features(val activated: Map<Feature, FeatureSupport>, val unknown: Se
  Feature.ChannelBackupClient,
  Feature.ChannelBackupProvider,
  Feature.ExperimentalSplice,
+ Feature.Quiescence
  )
 
  operator fun invoke(bytes: ByteVector): Features = invoke(bytes.toByteArray())

src/commonMain/kotlin/fr/acinq/lightning/NodeParams.kt

@@ -203,6 +203,7 @@ data class NodeParams(
  Feature.PayToOpenClient to FeatureSupport.Optional,
  Feature.ChannelBackupClient to FeatureSupport.Optional,
  Feature.ExperimentalSplice to FeatureSupport.Optional,
+ Feature.Quiescence to FeatureSupport.Mandatory
  ),
  dustLimit = 546.sat,
  maxRemoteDustLimit = 600.sat,

src/commonMain/kotlin/fr/acinq/lightning/channel/ChannelAction.kt

@@ -128,5 +128,7 @@ sealed class ChannelAction {
  }
 
  data class EmitEvent(val event: ChannelEvents) : ChannelAction()
+
+ object Disconnect : ChannelAction()
  // @formatter:on
 }

src/commonMain/kotlin/fr/acinq/lightning/channel/ChannelCommand.kt

@@ -61,10 +61,11 @@ sealed class ChannelCommand {
  data class WatchReceived(val watch: WatchEvent) : ChannelCommand()
 
  sealed interface ForbiddenDuringSplice
+ sealed interface ForbiddenDuringQuiescence
  sealed class Htlc : ChannelCommand() {
- data class Add(val amount: MilliSatoshi, val paymentHash: ByteVector32, val cltvExpiry: CltvExpiry, val onion: OnionRoutingPacket, val paymentId: UUID, val commit: Boolean = false) : Htlc(), ForbiddenDuringSplice
+ data class Add(val amount: MilliSatoshi, val paymentHash: ByteVector32, val cltvExpiry: CltvExpiry, val onion: OnionRoutingPacket, val paymentId: UUID, val commit: Boolean = false) : Htlc(), ForbiddenDuringSplice, ForbiddenDuringQuiescence
 
- sealed class Settlement : Htlc(), ForbiddenDuringSplice {
+ sealed class Settlement : Htlc(), ForbiddenDuringSplice, ForbiddenDuringQuiescence {
  abstract val id: Long
 
  data class Fulfill(override val id: Long, val r: ByteVector32, val commit: Boolean = false) : Settlement()
@@ -80,7 +81,7 @@ sealed class ChannelCommand {
 
  sealed class Commitment : ChannelCommand() {
  object Sign : Commitment(), ForbiddenDuringSplice
- data class UpdateFee(val feerate: FeeratePerKw, val commit: Boolean = false) : Commitment(), ForbiddenDuringSplice
+ data class UpdateFee(val feerate: FeeratePerKw, val commit: Boolean = false) : Commitment(), ForbiddenDuringSplice, ForbiddenDuringQuiescence
  object CheckHtlcTimeout : Commitment()
  sealed class Splice : Commitment() {
  data class Request(val replyTo: CompletableDeferred<Response>, val spliceIn: SpliceIn?, val spliceOut: SpliceOut?, val feerate: FeeratePerKw, val origins: List<Origin.PayToOpenOrigin> = emptyList()) : Splice() {
@@ -108,7 +109,8 @@ sealed class ChannelCommand {
  object InsufficientFunds : Failure()
  object InvalidSpliceOutPubKeyScript : Failure()
  object SpliceAlreadyInProgress : Failure()
- object ChannelNotIdle : Failure()
+ object ConcurrentRemoteSplice : Failure()
+ object ChannelNotQuiescent : Failure()
  data class FundingFailure(val reason: FundingContributionFailure) : Failure()
  object CannotStartSession : Failure()
  data class InteractiveTxSessionFailed(val reason: InteractiveTxSessionAction.RemoteFailure) : Failure()
@@ -121,7 +123,7 @@ sealed class ChannelCommand {
  }
 
  sealed class Close : ChannelCommand() {
- data class MutualClose(val scriptPubKey: ByteVector?, val feerates: ClosingFeerates?) : Close()
+ data class MutualClose(val scriptPubKey: ByteVector?, val feerates: ClosingFeerates?) : Close(), ForbiddenDuringSplice, ForbiddenDuringQuiescence
  object ForceClose : Close()
  }
 

src/commonMain/kotlin/fr/acinq/lightning/channel/ChannelException.kt

@@ -41,7 +41,7 @@ data class InvalidRbfNonInitiator (override val channelId: Byte
 data class InvalidRbfAttempt (override val channelId: ByteVector32) : ChannelException(channelId, "invalid rbf attempt")
 data class InvalidSpliceAlreadyInProgress (override val channelId: ByteVector32) : ChannelException(channelId, "invalid splice attempt: the current splice attempt must be completed or aborted first")
 data class InvalidSpliceAbortNotAcked (override val channelId: ByteVector32) : ChannelException(channelId, "invalid splice attempt: our previous tx_abort has not been acked")
-data class InvalidSpliceChannelNotIdle (override val channelId: ByteVector32) : ChannelException(channelId, "invalid splice attempt: channel is not idle")
+data class InvalidSpliceNotQuiescent  (override val channelId: ByteVector32) : ChannelException(channelId, "invalid splice attempt: the channel is not quiescent")
 data class NoMoreHtlcsClosingInProgress (override val channelId: ByteVector32) : ChannelException(channelId, "cannot send new htlcs, closing in progress")
 data class ClosingAlreadyInProgress (override val channelId: ByteVector32) : ChannelException(channelId, "closing already in progress")
 data class CannotCloseWithUnsignedOutgoingHtlcs (override val channelId: ByteVector32) : ChannelException(channelId, "cannot close when there are unsigned outgoing htlc")
@@ -85,4 +85,5 @@ data class InvalidFailureCode (override val channelId: Byte
 data class PleasePublishYourCommitment (override val channelId: ByteVector32) : ChannelException(channelId, "please publish your local commitment")
 data class CommandUnavailableInThisState (override val channelId: ByteVector32, val state: String) : ChannelException(channelId, "cannot execute command in state=$state")
 data class ForbiddenDuringSplice (override val channelId: ByteVector32, val command: String?) : ChannelException(channelId, "cannot process $command while splicing")
+data class InvalidSpliceRequest (override val channelId: ByteVector32) : ChannelException(channelId, "invalid splice request")
 // @formatter:on

src/commonMain/kotlin/fr/acinq/lightning/channel/Commitments.kt

@@ -252,8 +252,6 @@ data class Commitment(
  return hasNoPendingHtlcs() && hasNoPendingFeeUpdate
  }
 
- fun isIdle(changes: CommitmentChanges): Boolean = hasNoPendingHtlcs() && changes.localChanges.all.isEmpty() && changes.remoteChanges.all.isEmpty()
-
  fun timedOutOutgoingHtlcs(blockHeight: Long): Set<UpdateAddHtlc> {
  fun expired(add: UpdateAddHtlc) = blockHeight >= add.cltvExpiry.toLong()
 
@@ -596,15 +594,32 @@ data class Commitments(
  }
 
  // @formatter:off
+ fun localIsQuiescent(): Boolean = changes.localChanges.all.isEmpty()
+ fun remoteIsQuiescent(): Boolean = changes.remoteChanges.all.isEmpty()
+ fun isQuiescent(): Boolean = localIsQuiescent() && remoteIsQuiescent()
  // HTLCs and pending changes are the same for all active commitments, so we don't need to loop through all of them.
- fun isIdle(): Boolean = active.first().isIdle(changes)
  fun hasNoPendingHtlcsOrFeeUpdate(): Boolean = active.first().hasNoPendingHtlcsOrFeeUpdate(changes)
  fun timedOutOutgoingHtlcs(currentHeight: Long): Set<UpdateAddHtlc> = active.first().timedOutOutgoingHtlcs(currentHeight)
  fun almostTimedOutIncomingHtlcs(currentHeight: Long, fulfillSafety: CltvExpiryDelta): Set<UpdateAddHtlc> = active.first().almostTimedOutIncomingHtlcs(currentHeight, fulfillSafety, changes)
  fun getOutgoingHtlcCrossSigned(htlcId: Long): UpdateAddHtlc? = active.first().getOutgoingHtlcCrossSigned(htlcId)
  fun getIncomingHtlcCrossSigned(htlcId: Long): UpdateAddHtlc? = active.first().getIncomingHtlcCrossSigned(htlcId)
  // @formatter:on
 
+ /**
+ * Whenever we're not sure the `IncomingPaymentHandler` has received our previous `ChannelAction.ProcessIncomingHtlcs`,
+ * or when we may have ignored the responses from the `IncomingPaymentHandler` (eg. while quiescent or disconnected),
+ * we need to reprocess those incoming HTLCs.
+ */
+ fun reprocessIncomingHtlcs(): List<ChannelAction.ProcessIncomingHtlc> {
+ // We are interested in incoming HTLCs, that have been *cross-signed* (otherwise they wouldn't have been forwarded to the payment handler).
+ // They signed it first, so the HTLC will first appear in our commitment tx, and later on in their commitment when we subsequently sign it.
+ // That's why we need to look in *their* commitment with direction=OUT.
+ //
+ // We also need to filter out htlcs that we already settled and signed (the settlement messages are being retransmitted).
+ val alreadySettled = changes.localChanges.signed.filterIsInstance<HtlcSettlementMessage>().map { it.id }.toSet()
+ return latest.remoteCommit.spec.htlcs.outgoings().filter { !alreadySettled.contains(it.id) }.map { ChannelAction.ProcessIncomingHtlc(it) }
+ }
+
  fun sendAdd(cmd: ChannelCommand.Htlc.Add, paymentId: UUID, blockHeight: Long): Either<ChannelException, Pair<Commitments, UpdateAddHtlc>> {
  val maxExpiry = Channel.MAX_CLTV_EXPIRY_DELTA.toCltvExpiry(blockHeight)
  // we don't want to use too high a refund timeout, because our funds will be locked during that time if the payment is never fulfilled

src/commonMain/kotlin/fr/acinq/lightning/channel/InteractiveTx.kt

@@ -897,10 +897,33 @@ sealed class RbfStatus {
  object RbfAborted : RbfStatus()
 }
 
+/** We're waiting for the channel to be quiescent. */
+sealed class QuiescenceNegotiation : SpliceStatus() {
+ abstract class Initiator : QuiescenceNegotiation() {
+ abstract val command: ChannelCommand.Commitment.Splice.Request
+ }
+ abstract class NonInitiator : QuiescenceNegotiation()
+}
+
+/** The channel is quiescent and a splice attempt was initiated. */
+sealed class QuiescentSpliceStatus : SpliceStatus()
+
 sealed class SpliceStatus {
  object None : SpliceStatus()
- data class Requested(val command: ChannelCommand.Commitment.Splice.Request, val spliceInit: SpliceInit) : SpliceStatus()
- data class InProgress(val replyTo: CompletableDeferred<ChannelCommand.Commitment.Splice.Response>?, val spliceSession: InteractiveTxSession, val localPushAmount: MilliSatoshi, val remotePushAmount: MilliSatoshi, val origins: List<Origin.PayToOpenOrigin>) : SpliceStatus()
- data class WaitingForSigs(val session: InteractiveTxSigningSession, val origins: List<Origin.PayToOpenOrigin>) : SpliceStatus()
- object Aborted : SpliceStatus()
+ /** We stop sending new updates and wait for our updates to be added to the local and remote commitments. */
+ data class QuiescenceRequested(override val command: ChannelCommand.Commitment.Splice.Request) : QuiescenceNegotiation.Initiator()
+ /** Our updates have been added to the local and remote commitments, we wait for our peer to do the same. */
+ data class InitiatorQuiescent(override val command: ChannelCommand.Commitment.Splice.Request) : QuiescenceNegotiation.Initiator()
+ /** Our peer has asked us to stop sending new updates and wait for our updates to be added to the local and remote commitments. */
+ data class ReceivedStfu(val stfu: Stfu) : QuiescenceNegotiation.NonInitiator()
+ /** Our updates have been added to the local and remote commitments, we wait for our peer to use the now quiescent channel. */
+ object NonInitiatorQuiescent : QuiescentSpliceStatus()
+ /** We told our peer we want to splice funds in the channel. */
+ data class Requested(val command: ChannelCommand.Commitment.Splice.Request, val spliceInit: SpliceInit) : QuiescentSpliceStatus()
+ /** We both agreed to splice and are building the splice transaction. */
+ data class InProgress(val replyTo: CompletableDeferred<ChannelCommand.Commitment.Splice.Response>?, val spliceSession: InteractiveTxSession, val localPushAmount: MilliSatoshi, val remotePushAmount: MilliSatoshi, val origins: List<Origin.PayToOpenOrigin>) : QuiescentSpliceStatus()
+ /** The splice transaction has been negotiated, we're exchanging signatures. */
+ data class WaitingForSigs(val session: InteractiveTxSigningSession, val origins: List<Origin.PayToOpenOrigin>) : QuiescentSpliceStatus()
+ /** The splice attempt was aborted by us, we're waiting for our peer to ack. */
+ object Aborted : QuiescentSpliceStatus()
 }