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)
+    }
+
 }
 
 @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/ChannelCommand.kt

@@ -64,10 +64,11 @@ 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()
@@ -83,7 +84,7 @@ 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() {
@@ -111,7 +112,8 @@ 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()
@@ -124,7 +126,7 @@ 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

@@ -39,7 +39,7 @@ 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")
@@ -83,4 +83,6 @@ 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 ForbiddenDuringQuiescence               (override val channelId: ByteVector32, val command: String?) : ChannelException(channelId, "cannot process $command while quiescent")
+data class InvalidSpliceRequest                    (override val channelId: ByteVector32) : ChannelException(channelId, "invalid splice request")
 // @formatter:on

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

@@ -241,6 +241,10 @@ data class Commitment(
         return hasNoPendingHtlcs() && hasNoPendingFeeUpdate
     }
 
+    fun hasPendingOrProposedHtlcs(changes: CommitmentChanges): Boolean {
+        return !hasNoPendingHtlcs() || changes.localChanges.all.filterIsInstance<UpdateAddHtlc>().isNotEmpty() || changes.remoteChanges.all.filterIsInstance<UpdateAddHtlc>().isNotEmpty()
+    }
+
     fun isIdle(changes: CommitmentChanges): Boolean = hasNoPendingHtlcs() && changes.localChanges.all.isEmpty() && changes.remoteChanges.all.isEmpty()
 
     fun timedOutOutgoingHtlcs(blockHeight: Long): Set<UpdateAddHtlc> {
@@ -554,9 +558,13 @@ 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 hasPendingOrProposedHtlcs(): Boolean = active.first().hasPendingOrProposedHtlcs(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)

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

@@ -877,10 +877,33 @@ 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()
 }

src/commonMain/kotlin/fr/acinq/lightning/channel/states/Channel.kt

@@ -613,6 +613,9 @@ sealed class ChannelStateWithCommitments : PersistedChannelState() {
             null
         }
     }
+
+    // in Normal during splice we cache htlc settlements and process them when we end quiescence
+    var settlementStash: List<ChannelCommand.Htlc.Settlement> = emptyList()
 }
 
 object Channel {