ACINQ · thomash-acinq · Oct 9, 2024
diff --git a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/Features.kt b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/Features.kt
@@ -133,6 +133,13 @@ sealed class Feature {
         override val scopes: Set<FeatureScope> get() = setOf(FeatureScope.Init, FeatureScope.Node)
     }
 
+    @Serializable
+    object ProvideStorage : Feature() {
+        override val rfcName get() = "option_provide_storage"
+        override val mandatory get() = 42
+        override val scopes: Set<FeatureScope> get() = setOf(FeatureScope.Init, FeatureScope.Node)
+    }
+
     @Serializable
     object ChannelType : Feature() {
         override val rfcName get() = "option_channel_type"
@@ -224,15 +231,15 @@ sealed class Feature {
         override val scopes: Set<FeatureScope> get() = setOf(FeatureScope.Init, FeatureScope.Node)
     }
 
-    /** This feature bit should be activated when a node wants to send channel backups to their peers. */
+    /** This feature is deprecated but must be kept to allow deserialization of old backups. */
     @Serializable
     object ChannelBackupClient : Feature() {
         override val rfcName get() = "channel_backup_client"
         override val mandatory get() = 144
         override val scopes: Set<FeatureScope> get() = setOf(FeatureScope.Init)
     }
 
-    /** This feature bit should be activated when a node stores channel backups for their peers. */
+    /** This feature is deprecated but must be kept to allow deserialization of old backups. */
     @Serializable
     object ChannelBackupProvider : Feature() {
         override val rfcName get() = "channel_backup_provider"
@@ -337,6 +344,7 @@ data class Features(val activated: Map<Feature, FeatureSupport>, val unknown: Se
             Feature.ShutdownAnySegwit,
             Feature.DualFunding,
             Feature.Quiescence,
+            Feature.ProvideStorage,
             Feature.ChannelType,
             Feature.PaymentMetadata,
             Feature.TrampolinePayment,

diff --git a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/NodeParams.kt b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/NodeParams.kt
@@ -158,6 +158,7 @@ data class NodeParams(
     val paymentRecipientExpiryParams: RecipientCltvExpiryParams,
     val zeroConfPeers: Set<PublicKey>,
     val liquidityPolicy: MutableStateFlow<LiquidityPolicy>,
+    val usePeerStorage: Boolean,
 ) {
     val nodePrivateKey get() = keyManager.nodeKeys.nodeKey.privateKey
     val nodeId get() = keyManager.nodeKeys.nodeKey.publicKey
@@ -207,7 +208,6 @@ data class NodeParams(
             Feature.ExperimentalTrampolinePayment to FeatureSupport.Optional,
             Feature.ZeroReserveChannels to FeatureSupport.Optional,
             Feature.WakeUpNotificationClient to FeatureSupport.Optional,
-            Feature.ChannelBackupClient to FeatureSupport.Optional,
             Feature.ExperimentalSplice to FeatureSupport.Optional,
             Feature.OnTheFlyFunding to FeatureSupport.Optional,
             Feature.FundingFeeCredit to FeatureSupport.Optional,
@@ -254,6 +254,7 @@ data class NodeParams(
                 maxAllowedFeeCredit = 0.msat
             )
         ),
+        usePeerStorage = true,
     )
 
     /**

diff --git a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/ChannelCommand.kt b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/ChannelCommand.kt
@@ -60,6 +60,7 @@ sealed class ChannelCommand {
     }
 
     data class MessageReceived(val message: LightningMessage) : ChannelCommand()
+    data object PeerBackupReceived : ChannelCommand()
     data class WatchReceived(val watch: WatchEvent) : ChannelCommand()
 
     sealed interface ForbiddenDuringSplice

diff --git a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/Commitments.kt b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/Commitments.kt
@@ -566,7 +566,6 @@ data class Commitments(
     val payments: Map<Long, UUID>, // for outgoing htlcs, maps to paymentId
     val remoteNextCommitInfo: Either<WaitingForRevocation, PublicKey>, // this one is tricky, it must be kept in sync with Commitment.nextRemoteCommit
     val remotePerCommitmentSecrets: ShaChain,
-    val remoteChannelData: EncryptedChannelData = EncryptedChannelData.empty
 ) {
     init {
         require(active.isNotEmpty()) { "there must be at least one active commitment" }
@@ -794,7 +793,6 @@ data class Commitments(
                 localChanges = changes.localChanges.copy(acked = emptyList()),
                 remoteChanges = changes.remoteChanges.copy(proposed = emptyList(), acked = changes.remoteChanges.acked + changes.remoteChanges.proposed)
             ),
-            remoteChannelData = commits.last().channelData // the last message is the most recent
         )
         return Either.Right(Pair(commitments1, revocation))
     }
@@ -849,7 +847,6 @@ data class Commitments(
             remoteNextCommitInfo = Either.Right(revocation.nextPerCommitmentPoint),
             remotePerCommitmentSecrets = remotePerCommitmentSecrets.addHash(revocation.perCommitmentSecret.value, 0xFFFFFFFFFFFFL - remoteCommitIndex),
             payments = payments1,
-            remoteChannelData = revocation.channelData
         )
         return Either.Right(Pair(commitments1, actions.toList()))
     }

diff --git a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Channel.kt b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Channel.kt
@@ -62,28 +62,12 @@ sealed class ChannelState {
     suspend fun ChannelContext.process(cmd: ChannelCommand): Pair<ChannelState, List<ChannelAction>> {
         return try {
             processInternal(cmd)
-                .let { (newState, actions) -> Pair(newState, newState.run { maybeAddBackupToMessages(actions) }) }
                 .let { (newState, actions) -> Pair(newState, actions + onTransition(newState)) }
         } catch (t: Throwable) {
             handleLocalError(cmd, t)
         }
     }
 
-    /** Update outgoing messages to include an encrypted backup when necessary. */
-    private fun ChannelContext.maybeAddBackupToMessages(actions: List<ChannelAction>): List<ChannelAction> = when {
-        this@ChannelState is PersistedChannelState && staticParams.nodeParams.features.hasFeature(Feature.ChannelBackupClient) -> actions.map {
-            when {
-                it is ChannelAction.Message.Send && it.message is TxSignatures -> it.copy(message = it.message.withChannelData(EncryptedChannelData.from(privateKey, this@ChannelState), logger))
-                it is ChannelAction.Message.Send && it.message is CommitSig -> it.copy(message = it.message.withChannelData(EncryptedChannelData.from(privateKey, this@ChannelState), logger))
-                it is ChannelAction.Message.Send && it.message is RevokeAndAck -> it.copy(message = it.message.withChannelData(EncryptedChannelData.from(privateKey, this@ChannelState), logger))
-                it is ChannelAction.Message.Send && it.message is Shutdown -> it.copy(message = it.message.withChannelData(EncryptedChannelData.from(privateKey, this@ChannelState), logger))
-                it is ChannelAction.Message.Send && it.message is ClosingSigned -> it.copy(message = it.message.withChannelData(EncryptedChannelData.from(privateKey, this@ChannelState), logger))
-                else -> it
-            }
-        }
-        else -> actions
-    }
-
     /** Add actions for some transitions */
     private fun ChannelContext.onTransition(newState: ChannelState): List<ChannelAction> {
         val oldState = when (this@ChannelState) {
@@ -301,7 +285,7 @@ sealed class ChannelState {
 sealed class PersistedChannelState : ChannelState() {
     abstract val channelId: ByteVector32
 
-    internal fun ChannelContext.createChannelReestablish(): HasEncryptedChannelData = when (val state = this@PersistedChannelState) {
+    internal fun ChannelContext.createChannelReestablish(): ChannelReestablish = when (val state = this@PersistedChannelState) {
         is WaitForFundingSigned -> {
             val myFirstPerCommitmentPoint = keyManager.channelKeys(state.channelParams.localParams.fundingKeyPath).commitmentPoint(0)
             ChannelReestablish(
@@ -311,7 +295,7 @@ sealed class PersistedChannelState : ChannelState() {
                 yourLastCommitmentSecret = PrivateKey(ByteVector32.Zeroes),
                 myCurrentPerCommitmentPoint = myFirstPerCommitmentPoint,
                 TlvStream(ChannelReestablishTlv.NextFunding(state.signingSession.fundingTx.txId))
-            ).withChannelData(state.remoteChannelData, logger)
+            )
         }
         is ChannelStateWithCommitments -> {
             val yourLastPerCommitmentSecret = state.commitments.remotePerCommitmentSecrets.lastIndex?.let { state.commitments.remotePerCommitmentSecrets.getHash(it) } ?: ByteVector32.Zeroes
@@ -329,7 +313,7 @@ sealed class PersistedChannelState : ChannelState() {
                 yourLastCommitmentSecret = PrivateKey(yourLastPerCommitmentSecret),
                 myCurrentPerCommitmentPoint = myCurrentPerCommitmentPoint,
                 tlvStream = tlvs
-            ).withChannelData(state.commitments.remoteChannelData, logger)
+            )
         }
     }
 

diff --git a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Closing.kt b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Closing.kt
@@ -281,9 +281,6 @@ data class Closing(
                             null -> Pair(closing1, listOf())
                             else -> {
                                 logger.info { "channel is now closed" }
-                                if (closingType !is MutualClose) {
-                                    logger.debug { "last known remoteChannelData=${commitments.remoteChannelData}" }
-                                }
                                 Pair(Closed(closing1), listOf(setClosingStatus(closingType)))
                             }
                         }
@@ -375,6 +372,7 @@ data class Closing(
             is ChannelCommand.Funding -> unhandled(cmd)
             is ChannelCommand.Connected -> unhandled(cmd)
             is ChannelCommand.Disconnected -> unhandled(cmd)
+            is ChannelCommand.PeerBackupReceived -> unhandled(cmd)
         }
     }
 

diff --git a/.../src/commonMain/kotlin/fr/acinq/lightning/channel/states/LegacyWaitForFundingConfirmed.kt b/.../src/commonMain/kotlin/fr/acinq/lightning/channel/states/LegacyWaitForFundingConfirmed.kt
@@ -80,6 +80,7 @@ data class LegacyWaitForFundingConfirmed(
             is ChannelCommand.Closing -> unhandled(cmd)
             is ChannelCommand.Connected -> unhandled(cmd)
             is ChannelCommand.Disconnected -> Pair(Offline(this@LegacyWaitForFundingConfirmed), listOf())
+            is ChannelCommand.PeerBackupReceived -> unhandled(cmd)
         }
     }
 }
diff --git a/...ore/src/commonMain/kotlin/fr/acinq/lightning/channel/states/LegacyWaitForFundingLocked.kt b/...ore/src/commonMain/kotlin/fr/acinq/lightning/channel/states/LegacyWaitForFundingLocked.kt
@@ -74,6 +74,7 @@ data class LegacyWaitForFundingLocked(
             is ChannelCommand.Closing -> unhandled(cmd)
             is ChannelCommand.Connected -> unhandled(cmd)
             is ChannelCommand.Disconnected -> Pair(Offline(this@LegacyWaitForFundingLocked), listOf())
+            is ChannelCommand.PeerBackupReceived -> unhandled(cmd)
         }
     }
 }
diff --git a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Negotiating.kt b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Negotiating.kt
@@ -89,7 +89,6 @@ data class Negotiating(
                                                     closingTxProposed.last() + listOf(ClosingTxProposed(closingTx, closingSigned))
                                                 )
                                                 val nextState = [email protected](
-                                                    commitments = commitments.copy(remoteChannelData = cmd.message.channelData),
                                                     closingTxProposed = closingProposed1,
                                                     bestUnpublishedClosingTx = signedClosingTx
                                                 )
@@ -127,7 +126,6 @@ data class Negotiating(
                                                         closingTxProposed.last() + listOf(ClosingTxProposed(closingTx, closingSigned))
                                                     )
                                                     val nextState = [email protected](
-                                                        commitments = commitments.copy(remoteChannelData = cmd.message.channelData),
                                                         closingTxProposed = closingProposed1,
                                                         bestUnpublishedClosingTx = signedClosingTx
                                                     )
@@ -179,6 +177,7 @@ data class Negotiating(
             is ChannelCommand.Closing -> unhandled(cmd)
             is ChannelCommand.Connected -> unhandled(cmd)
             is ChannelCommand.Disconnected -> Pair(Offline(this@Negotiating), listOf())
+            is ChannelCommand.PeerBackupReceived -> unhandled(cmd)
         }
     }
 

diff --git a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Normal.kt b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Normal.kt
@@ -178,7 +178,7 @@ data class Normal(
                                     logger.info { "waiting for tx_sigs" }
                                     Pair([email protected](spliceStatus = spliceStatus.copy(session = signingSession1)), listOf())
                                 }
-                                is InteractiveTxSigningSessionAction.SendTxSigs -> sendSpliceTxSigs(spliceStatus.origins, action, spliceStatus.liquidityPurchase, cmd.message.channelData)
+                                is InteractiveTxSigningSessionAction.SendTxSigs -> sendSpliceTxSigs(spliceStatus.origins, action, spliceStatus.liquidityPurchase)
                             }
                         }
                         ignoreRetransmittedCommitSig(cmd.message) -> {
@@ -298,7 +298,7 @@ data class Normal(
                                     }
                                     is Either.Right -> {
                                         // no, let's sign right away
-                                        val newState = [email protected](remoteShutdown = cmd.message, commitments = commitments.copy(remoteChannelData = cmd.message.channelData))
+                                        val newState = [email protected](remoteShutdown = cmd.message)
                                         Pair(newState, listOf(ChannelAction.Message.SendToSelf(ChannelCommand.Commitment.Sign)))
                                     }
                                 }
@@ -308,18 +308,17 @@ data class Normal(
                                 val actions = mutableListOf<ChannelAction>()
                                 val localShutdown = [email protected] ?: Shutdown(channelId, commitments.params.localParams.defaultFinalScriptPubKey)
                                 if ([email protected] == null) actions.add(ChannelAction.Message.Send(localShutdown))
-                                val commitments1 = commitments.copy(remoteChannelData = cmd.message.channelData)
                                 when {
-                                    commitments1.hasNoPendingHtlcsOrFeeUpdate() && paysClosingFees -> {
+                                    commitments.hasNoPendingHtlcsOrFeeUpdate() && paysClosingFees -> {
                                         val (closingTx, closingSigned) = Helpers.Closing.makeFirstClosingTx(
                                             channelKeys(),
-                                            commitments1.latest,
+                                            commitments.latest,
                                             localShutdown.scriptPubKey.toByteArray(),
                                             cmd.message.scriptPubKey.toByteArray(),
                                             closingFeerates ?: ClosingFeerates(currentOnChainFeerates().mutualCloseFeerate),
                                         )
                                         val nextState = Negotiating(
-                                            commitments1,
+                                            commitments,
                                             localShutdown,
                                             cmd.message,
                                             listOf(listOf(ClosingTxProposed(closingTx, closingSigned))),
@@ -329,14 +328,14 @@ data class Normal(
                                         actions.addAll(listOf(ChannelAction.Storage.StoreState(nextState), ChannelAction.Message.Send(closingSigned)))
                                         Pair(nextState, actions)
                                     }
-                                    commitments1.hasNoPendingHtlcsOrFeeUpdate() -> {
-                                        val nextState = Negotiating(commitments1, localShutdown, cmd.message, listOf(listOf()), null, closingFeerates)
+                                    commitments.hasNoPendingHtlcsOrFeeUpdate() -> {
+                                        val nextState = Negotiating(commitments, localShutdown, cmd.message, listOf(listOf()), null, closingFeerates)
                                         actions.add(ChannelAction.Storage.StoreState(nextState))
                                         Pair(nextState, actions)
                                     }
                                     else -> {
                                         // there are some pending changes, we need to wait for them to be settled (fail/fulfill htlcs and sign fee updates)
-                                        val nextState = ShuttingDown(commitments1, localShutdown, cmd.message, closingFeerates)
+                                        val nextState = ShuttingDown(commitments, localShutdown, cmd.message, closingFeerates)
                                         actions.add(ChannelAction.Storage.StoreState(nextState))
                                         Pair(nextState, actions)
                                     }
@@ -670,7 +669,7 @@ data class Normal(
                                 }
                                 is Either.Right -> {
                                     val action: InteractiveTxSigningSessionAction.SendTxSigs = res.value
-                                    sendSpliceTxSigs(spliceStatus.origins, action, spliceStatus.liquidityPurchase, cmd.message.channelData)
+                                    sendSpliceTxSigs(spliceStatus.origins, action, spliceStatus.liquidityPurchase)
                                 }
                             }
                         }
@@ -844,20 +843,20 @@ data class Normal(
             is ChannelCommand.Connected -> unhandled(cmd)
             is ChannelCommand.Closing -> unhandled(cmd)
             is ChannelCommand.Init -> unhandled(cmd)
+            is ChannelCommand.PeerBackupReceived -> unhandled(cmd)
         }
     }
 
     private fun ChannelContext.sendSpliceTxSigs(
         origins: List<Origin>,
         action: InteractiveTxSigningSessionAction.SendTxSigs,
         liquidityPurchase: LiquidityAds.Purchase?,
-        remoteChannelData: EncryptedChannelData
     ): Pair<Normal, List<ChannelAction>> {
         logger.info { "sending tx_sigs" }
         // We watch for confirmation in all cases, to allow pruning outdated commitments when transactions confirm.
         val fundingMinDepth = Helpers.minDepthForFunding(staticParams.nodeParams, action.fundingTx.fundingParams.fundingAmount)
         val watchConfirmed = WatchConfirmed(channelId, action.commitment.fundingTxId, action.commitment.commitInput.txOut.publicKeyScript, fundingMinDepth.toLong(), BITCOIN_FUNDING_DEPTHOK)
-        val commitments = commitments.add(action.commitment).copy(remoteChannelData = remoteChannelData)
+        val commitments = commitments.add(action.commitment)
         val nextState = [email protected](commitments = commitments, spliceStatus = SpliceStatus.None)
         val actions = buildList {
             add(ChannelAction.Storage.StoreState(nextState))

diff --git a/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Offline.kt b/modules/core/src/commonMain/kotlin/fr/acinq/lightning/channel/states/Offline.kt
@@ -1,7 +1,6 @@
 package fr.acinq.lightning.channel.states
 
 import fr.acinq.bitcoin.utils.Either
-import fr.acinq.lightning.Feature
 import fr.acinq.lightning.ShortChannelId
 import fr.acinq.lightning.blockchain.*
 import fr.acinq.lightning.channel.*
@@ -37,7 +36,7 @@ data class Offline(val state: PersistedChannelState) : ChannelState() {
                     }
                     is ChannelStateWithCommitments -> {
                         logger.info { "syncing ${state::class}" }
-                        val sendChannelReestablish = !staticParams.nodeParams.features.hasFeature(Feature.ChannelBackupClient)
+                        val sendChannelReestablish = !staticParams.nodeParams.usePeerStorage
                         val actions = buildList {
                             if (!sendChannelReestablish) {
                                 // We wait for them to go first, which lets us restore from the latest backup if we've lost data.
@@ -126,6 +125,7 @@ data class Offline(val state: PersistedChannelState) : ChannelState() {
             is ChannelCommand.Init -> unhandled(cmd)
             is ChannelCommand.Funding -> unhandled(cmd)
             is ChannelCommand.Closing -> unhandled(cmd)
+            is ChannelCommand.PeerBackupReceived -> unhandled(cmd)
         }
     }
 }