Remove support for push_amount

With the updated on-the-fly funding protocol, we're using liquidity ads
instead of an unofficial `push_amount` TLV. We can thus remove usage of
`push_amount`s everywhere, which simplifies the codebase.

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

@@ -10,7 +10,6 @@ import fr.acinq.lightning.channel.states.ClosingFeerates
 import fr.acinq.lightning.channel.states.PersistedChannelState
 import fr.acinq.lightning.crypto.KeyManager
 import fr.acinq.lightning.utils.UUID
-import fr.acinq.lightning.utils.msat
 import fr.acinq.lightning.wire.FailureMessage
 import fr.acinq.lightning.wire.LightningMessage
 import fr.acinq.lightning.wire.LiquidityAds
@@ -27,7 +26,6 @@ sealed class ChannelCommand {
         data class Initiator(
             val replyTo: CompletableDeferred<ChannelFundingResponse>,
             val fundingAmount: Satoshi,
-            val pushAmount: MilliSatoshi,
             val walletInputs: List<WalletState.Utxo>,
             val commitTxFeerate: FeeratePerKw,
             val fundingTxFeerate: FeeratePerKw,
@@ -46,7 +44,6 @@ sealed class ChannelCommand {
             val replyTo: CompletableDeferred<ChannelFundingResponse>,
             val temporaryChannelId: ByteVector32,
             val fundingAmount: Satoshi,
-            val pushAmount: MilliSatoshi,
             val walletInputs: List<WalletState.Utxo>,
             val localParams: LocalParams,
             val channelConfig: ChannelConfig,
@@ -98,11 +95,10 @@ sealed class ChannelCommand {
                 val feerate: FeeratePerKw,
                 val origins: List<Origin>
             ) : Splice() {
-                val pushAmount: MilliSatoshi = spliceIn?.pushAmount ?: 0.msat
                 val spliceOutputs: List<TxOut> = spliceOut?.let { listOf(TxOut(it.amount, it.scriptPubKey)) } ?: emptyList()
                 val liquidityFees: LiquidityAds.Fees? = requestRemoteFunding?.fees(feerate, isChannelCreation = false)
 
-                data class SpliceIn(val walletInputs: List<WalletState.Utxo>, val pushAmount: MilliSatoshi = 0.msat)
+                data class SpliceIn(val walletInputs: List<WalletState.Utxo>)
                 data class SpliceOut(val amount: Satoshi, val scriptPubKey: ByteVector)
             }
         }

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

@@ -72,11 +72,6 @@ object Helpers {
             return Either.Left(InvalidChainHash(open.temporaryChannelId, local = nodeParams.chainHash, remote = open.chainHash))
         }
 
-        // BOLT #2: The receiving node MUST fail the channel if: push_msat is greater than funding_satoshis * 1000.
-        if (open.pushAmount > open.fundingAmount) {
-            return Either.Left(InvalidPushAmount(open.temporaryChannelId, open.pushAmount, open.fundingAmount.toMilliSatoshi()))
-        }
-
         // BOLT #2: The receiving node MUST fail the channel if: to_self_delay is unreasonably large.
         if (open.toSelfDelay > Channel.MAX_TO_SELF_DELAY || open.toSelfDelay > nodeParams.maxToLocalDelayBlocks) {
             return Either.Left(ToSelfDelayTooHigh(open.temporaryChannelId, open.toSelfDelay, nodeParams.maxToLocalDelayBlocks))
@@ -122,10 +117,6 @@ object Helpers {
             return Either.Left(InvalidFundingAmount(accept.temporaryChannelId, accept.fundingAmount))
         }
 
-        if (accept.pushAmount > accept.fundingAmount) {
-            return Either.Left(InvalidPushAmount(accept.temporaryChannelId, accept.pushAmount, accept.fundingAmount.toMilliSatoshi()))
-        }
-
         if (accept.maxAcceptedHtlcs > Channel.MAX_ACCEPTED_HTLCS) {
             return Either.Left(InvalidMaxAcceptedHtlcs(accept.temporaryChannelId, accept.maxAcceptedHtlcs, Channel.MAX_ACCEPTED_HTLCS))
         }

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

@@ -270,11 +270,9 @@ data class FundingContributions(val inputs: List<InteractiveTxInput.Outgoing>, v
             swapInKeys: KeyManager.SwapInOnChainKeys,
             params: InteractiveTxParams,
             walletInputs: List<WalletState.Utxo>,
-            localPushAmount: MilliSatoshi,
-            remotePushAmount: MilliSatoshi,
             liquidityPurchase: LiquidityAds.Purchase?
         ): Either<FundingContributionFailure, FundingContributions> {
-            return create(channelKeys, swapInKeys, params, null, walletInputs, listOf(), localPushAmount, remotePushAmount, liquidityPurchase)
+            return create(channelKeys, swapInKeys, params, null, walletInputs, listOf(), liquidityPurchase)
         }
 
         /**
@@ -290,8 +288,6 @@ data class FundingContributions(val inputs: List<InteractiveTxInput.Outgoing>, v
             sharedUtxo: Pair<SharedFundingInput, SharedFundingInputBalances>?,
             walletInputs: List<WalletState.Utxo>,
             localOutputs: List<TxOut>,
-            localPushAmount: MilliSatoshi,
-            remotePushAmount: MilliSatoshi,
             liquidityPurchase: LiquidityAds.Purchase?,
             changePubKey: PublicKey? = null
         ): Either<FundingContributionFailure, FundingContributions> {
@@ -310,9 +306,9 @@ data class FundingContributions(val inputs: List<InteractiveTxInput.Outgoing>, v
 
             val liquidityFees = params.liquidityFees(liquidityPurchase)
             val nextLocalBalanceBeforePush = (sharedUtxo?.second?.toLocal ?: 0.msat) + params.localContribution.toMilliSatoshi()
-            val nextLocalBalanceAfterPush = (sharedUtxo?.second?.toLocal ?: 0.msat) + params.localContribution.toMilliSatoshi() - localPushAmount + remotePushAmount - liquidityFees
+            val nextLocalBalanceAfterPush = (sharedUtxo?.second?.toLocal ?: 0.msat) + params.localContribution.toMilliSatoshi() - liquidityFees
             val nextRemoteBalanceBeforePush = (sharedUtxo?.second?.toRemote ?: 0.msat) + params.remoteContribution.toMilliSatoshi()
-            val nextRemoteBalanceAfterPush = (sharedUtxo?.second?.toRemote ?: 0.msat) + params.remoteContribution.toMilliSatoshi() + localPushAmount - remotePushAmount + liquidityFees
+            val nextRemoteBalanceAfterPush = (sharedUtxo?.second?.toRemote ?: 0.msat) + params.remoteContribution.toMilliSatoshi() + liquidityFees
             if (nextLocalBalanceAfterPush < 0.msat || nextRemoteBalanceAfterPush < 0.msat) {
                 return Either.Left(FundingContributionFailure.InvalidFundingBalances(params.fundingAmount, nextLocalBalanceAfterPush, nextRemoteBalanceAfterPush))
             }
@@ -1091,8 +1087,6 @@ data class InteractiveTxSigningSession(
             fundingParams: InteractiveTxParams,
             fundingTxIndex: Long,
             sharedTx: SharedTransaction,
-            localPushAmount: MilliSatoshi,
-            remotePushAmount: MilliSatoshi,
             liquidityPurchase: LiquidityAds.Purchase?,
             localCommitmentIndex: Long,
             remoteCommitmentIndex: Long,
@@ -1109,8 +1103,8 @@ data class InteractiveTxSigningSession(
                 channelParams.channelId,
                 channelParams.localParams, channelParams.remoteParams,
                 fundingAmount = sharedTx.sharedOutput.amount,
-                toLocal = sharedTx.sharedOutput.localAmount - localPushAmount + remotePushAmount - liquidityFees,
-                toRemote = sharedTx.sharedOutput.remoteAmount - remotePushAmount + localPushAmount + liquidityFees,
+                toLocal = sharedTx.sharedOutput.localAmount - liquidityFees,
+                toRemote = sharedTx.sharedOutput.remoteAmount + liquidityFees,
                 localHtlcs = localHtlcs,
                 localCommitmentIndex = localCommitmentIndex,
                 remoteCommitmentIndex = remoteCommitmentIndex,
@@ -1203,8 +1197,6 @@ sealed class SpliceStatus {
     data class InProgress(
         val replyTo: CompletableDeferred<ChannelFundingResponse>?,
         val spliceSession: InteractiveTxSession,
-        val localPushAmount: MilliSatoshi,
-        val remotePushAmount: MilliSatoshi,
         val liquidityPurchase: LiquidityAds.Purchase?,
         val origins: List<Origin>
     ) : QuiescentSpliceStatus()

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

@@ -419,10 +419,9 @@ data class Normal(
                                                 lockTime = currentBlockHeight.toLong(),
                                                 feerate = spliceStatus.command.feerate,
                                                 fundingPubkey = channelKeys().fundingPubKey(parentCommitment.fundingTxIndex + 1),
-                                                pushAmount = spliceStatus.command.pushAmount,
                                                 requestFunding = spliceStatus.command.requestRemoteFunding,
                                             )
-                                            logger.info { "initiating splice with local.amount=${spliceInit.fundingContribution} local.push=${spliceInit.pushAmount}" }
+                                            logger.info { "initiating splice with local.amount=${spliceInit.fundingContribution}" }
                                             Pair(this@Normal.copy(spliceStatus = SpliceStatus.Requested(spliceStatus.command, spliceInit)), listOf(ChannelAction.Message.Send(spliceInit)))
                                         }
                                     } else {
@@ -453,12 +452,11 @@ data class Normal(
                         }
                         is SpliceStatus.NonInitiatorQuiescent ->
                             if (commitments.isQuiescent()) {
-                                logger.info { "accepting splice with remote.amount=${cmd.message.fundingContribution} remote.push=${cmd.message.pushAmount}" }
+                                logger.info { "accepting splice with remote.amount=${cmd.message.fundingContribution}" }
                                 val parentCommitment = commitments.active.first()
                                 val spliceAck = SpliceAck(
                                     channelId,
                                     fundingContribution = 0.sat, // only remote contributes to the splice
-                                    pushAmount = 0.msat,
                                     fundingPubkey = channelKeys().fundingPubKey(parentCommitment.fundingTxIndex + 1),
                                     willFund = null,
                                 )
@@ -489,8 +487,6 @@ data class Normal(
                                     spliceStatus = SpliceStatus.InProgress(
                                         replyTo = null,
                                         session,
-                                        localPushAmount = 0.msat,
-                                        remotePushAmount = cmd.message.pushAmount,
                                         liquidityPurchase = null,
                                         origins = listOf()
                                     )
@@ -511,7 +507,7 @@ data class Normal(
                     }
                     is SpliceAck -> when (spliceStatus) {
                         is SpliceStatus.Requested -> {
-                            logger.info { "our peer accepted our splice request with remote.amount=${cmd.message.fundingContribution} remote.push=${cmd.message.pushAmount} liquidityFees=${spliceStatus.command.liquidityFees}" }
+                            logger.info { "our peer accepted our splice request with remote.amount=${cmd.message.fundingContribution} liquidityFees=${spliceStatus.command.liquidityFees}" }
                             when (val liquidityPurchase = LiquidityAds.validateRemoteFunding(
                                 spliceStatus.command.requestRemoteFunding,
                                 remoteNodeId,
@@ -550,8 +546,6 @@ data class Normal(
                                         sharedUtxo = Pair(sharedInput, SharedFundingInputBalances(toLocal = parentCommitment.localCommit.spec.toLocal, toRemote = parentCommitment.localCommit.spec.toRemote, toHtlcs = parentCommitment.localCommit.spec.htlcs.map { it.add.amountMsat }.sum())),
                                         walletInputs = spliceStatus.command.spliceIn?.walletInputs ?: emptyList(),
                                         localOutputs = spliceStatus.command.spliceOutputs,
-                                        localPushAmount = spliceStatus.spliceInit.pushAmount,
-                                        remotePushAmount = cmd.message.pushAmount,
                                         liquidityPurchase = liquidityPurchase.value,
                                         changePubKey = null // we don't want a change output: we're spending every funds available
                                     )) {
@@ -579,8 +573,6 @@ data class Normal(
                                                         spliceStatus = SpliceStatus.InProgress(
                                                             replyTo = spliceStatus.command.replyTo,
                                                             interactiveTxSession,
-                                                            localPushAmount = spliceStatus.spliceInit.pushAmount,
-                                                            remotePushAmount = cmd.message.pushAmount,
                                                             liquidityPurchase = liquidityPurchase.value,
                                                             origins = spliceStatus.command.origins,
                                                         )
@@ -617,8 +609,6 @@ data class Normal(
                                         spliceStatus.spliceSession.fundingParams,
                                         fundingTxIndex = parentCommitment.fundingTxIndex + 1,
                                         interactiveTxAction.sharedTx,
-                                        localPushAmount = spliceStatus.localPushAmount,
-                                        remotePushAmount = spliceStatus.remotePushAmount,
                                         liquidityPurchase = spliceStatus.liquidityPurchase,
                                         localCommitmentIndex = parentCommitment.localCommit.index,
                                         remoteCommitmentIndex = parentCommitment.remoteCommit.index,

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

@@ -72,8 +72,6 @@ data class WaitForAcceptChannel(
                                     keyManager.swapInOnChainWallet,
                                     fundingParams,
                                     init.walletInputs,
-                                    lastSent.pushAmount,
-                                    accept.pushAmount,
                                     liquidityPurchase.value
                                 )) {
                                     is Either.Left -> {
@@ -100,8 +98,6 @@ data class WaitForAcceptChannel(
                                                     init.localParams,
                                                     remoteParams,
                                                     interactiveTxSession,
-                                                    lastSent.pushAmount,
-                                                    accept.pushAmount,
                                                     lastSent.commitmentFeerate,
                                                     accept.firstPerCommitmentPoint,
                                                     accept.secondPerCommitmentPoint,

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

@@ -2,21 +2,17 @@ package fr.acinq.lightning.channel.states
 
 import fr.acinq.bitcoin.TxId
 import fr.acinq.bitcoin.utils.Either
-import fr.acinq.lightning.MilliSatoshi
 import fr.acinq.lightning.ShortChannelId
 import fr.acinq.lightning.blockchain.BITCOIN_FUNDING_DEPTHOK
 import fr.acinq.lightning.blockchain.WatchConfirmed
 import fr.acinq.lightning.blockchain.WatchEventConfirmed
 import fr.acinq.lightning.channel.*
 import fr.acinq.lightning.utils.msat
-import fr.acinq.lightning.utils.toMilliSatoshi
 import fr.acinq.lightning.wire.*
 
 /** We wait for the channel funding transaction to confirm. */
 data class WaitForFundingConfirmed(
     override val commitments: Commitments,
-    val localPushAmount: MilliSatoshi,
-    val remotePushAmount: MilliSatoshi,
     val waitingSinceBlock: Long, // how many blocks have we been waiting for the funding tx to confirm
     val deferred: ChannelReady?,
     // We can have at most one ongoing RBF attempt.
@@ -85,12 +81,6 @@ data class WaitForFundingConfirmed(
                                 if (cmd.message.feerate < minNextFeerate) {
                                     logger.info { "rejecting rbf attempt: the new feerate must be at least $minNextFeerate (proposed=${cmd.message.feerate})" }
                                     Pair(this@WaitForFundingConfirmed.copy(rbfStatus = RbfStatus.RbfAborted), listOf(ChannelAction.Message.Send(TxAbort(channelId, InvalidRbfFeerate(channelId, cmd.message.feerate, minNextFeerate).message))))
-                                } else if (cmd.message.fundingContribution.toMilliSatoshi() < remotePushAmount) {
-                                    logger.info { "rejecting rbf attempt: invalid amount pushed (fundingAmount=${cmd.message.fundingContribution}, pushAmount=$remotePushAmount)" }
-                                    Pair(
-                                        this@WaitForFundingConfirmed.copy(rbfStatus = RbfStatus.RbfAborted),
-                                        listOf(ChannelAction.Message.Send(TxAbort(channelId, InvalidPushAmount(channelId, remotePushAmount, cmd.message.fundingContribution.toMilliSatoshi()).message)))
-                                    )
                                 } else {
                                     logger.info { "our peer wants to raise the feerate of the funding transaction (previous=${latestFundingTx.fundingParams.targetFeerate} target=${cmd.message.feerate})" }
                                     val fundingParams = InteractiveTxParams(
@@ -136,7 +126,7 @@ data class WaitForFundingConfirmed(
                             latestFundingTx.fundingParams.dustLimit,
                             rbfStatus.command.targetFeerate
                         )
-                        when (val contributions = FundingContributions.create(channelKeys(), keyManager.swapInOnChainWallet, fundingParams, rbfStatus.command.walletInputs, 0.msat, 0.msat, null)) {
+                        when (val contributions = FundingContributions.create(channelKeys(), keyManager.swapInOnChainWallet, fundingParams, rbfStatus.command.walletInputs, null)) {
                             is Either.Left -> {
                                 logger.warning { "error creating funding contributions: ${contributions.value}" }
                                 Pair(this@WaitForFundingConfirmed.copy(rbfStatus = RbfStatus.RbfAborted), listOf(ChannelAction.Message.Send(TxAbort(channelId, ChannelFundingError(channelId).message))))
@@ -175,8 +165,6 @@ data class WaitForFundingConfirmed(
                                     rbfSession1.fundingParams,
                                     fundingTxIndex = replacedCommitment.fundingTxIndex,
                                     interactiveTxAction.sharedTx,
-                                    localPushAmount,
-                                    remotePushAmount,
                                     liquidityPurchase = null,
                                     localCommitmentIndex = replacedCommitment.localCommit.index,
                                     remoteCommitmentIndex = replacedCommitment.remoteCommit.index,
@@ -321,8 +309,6 @@ data class WaitForFundingConfirmed(
         val watchConfirmed = WatchConfirmed(channelId, action.commitment.fundingTxId, action.commitment.commitInput.txOut.publicKeyScript, fundingMinDepth.toLong(), BITCOIN_FUNDING_DEPTHOK)
         val nextState = WaitForFundingConfirmed(
             commitments.add(action.commitment).copy(remoteChannelData = remoteChannelData),
-            localPushAmount,
-            remotePushAmount,
             waitingSinceBlock,
             deferred,
             RbfStatus.None