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Add support for push amount with dual funding (#2433)
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When using dual funding, both sides may push an initial amount to the remote
side. This is done with an experimental tlv that can be added to `open_channel2`
and `accept_channel2`.
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@t-bast
t-bast authored Sep 26, 2022
1 parent 3fdad68 commit 1b0ce80
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Showing 31 changed files with 289 additions and 112 deletions.
5 changes: 5 additions & 0 deletions eclair-core/src/main/scala/fr/acinq/eclair/channel/ChannelData.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,7 @@ case class INPUT_INIT_CHANNEL_INITIATOR(temporaryChannelId: ByteVector32,
case class INPUT_INIT_CHANNEL_NON_INITIATOR(temporaryChannelId: ByteVector32,
fundingContribution_opt: Option[Satoshi],
dualFunded: Boolean,
pushAmount_opt: Option[MilliSatoshi],
localParams: LocalParams,
remote: ActorRef,
remoteInit: Init,
Expand Down Expand Up @@ -498,11 +499,15 @@ final case class DATA_WAIT_FOR_ACCEPT_DUAL_FUNDED_CHANNEL(init: INPUT_INIT_CHANN
val channelId: ByteVector32 = lastSent.temporaryChannelId
}
final case class DATA_WAIT_FOR_DUAL_FUNDING_CREATED(channelId: ByteVector32,
localPushAmount: MilliSatoshi,
remotePushAmount: MilliSatoshi,
txBuilder: typed.ActorRef[InteractiveTxBuilder.Command],
deferred: Option[ChannelReady]) extends TransientChannelData
final case class DATA_WAIT_FOR_DUAL_FUNDING_CONFIRMED(commitments: Commitments,
fundingTx: SignedSharedTransaction,
fundingParams: InteractiveTxParams,
localPushAmount: MilliSatoshi,
remotePushAmount: MilliSatoshi,
previousFundingTxs: List[DualFundingTx],
waitingSince: BlockHeight, // how long have we been waiting for a funding tx to confirm
lastChecked: BlockHeight, // last time we checked if the channel was double-spent
Expand Down
26 changes: 17 additions & 9 deletions eclair-core/src/main/scala/fr/acinq/eclair/channel/Helpers.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -138,10 +138,11 @@ object Helpers {
// MUST reject the channel.
if (nodeParams.chainHash != open.chainHash) return Left(InvalidChainHash(open.temporaryChannelId, local = nodeParams.chainHash, remote = open.chainHash))

// BOLT #2: Channel funding limits
if (open.fundingAmount < nodeParams.channelConf.minFundingSatoshis(open.channelFlags.announceChannel) || open.fundingAmount > nodeParams.channelConf.maxFundingSatoshis) return Left(InvalidFundingAmount(open.temporaryChannelId, open.fundingAmount, nodeParams.channelConf.minFundingSatoshis(open.channelFlags.announceChannel), nodeParams.channelConf.maxFundingSatoshis))

// BOLT #2: Channel funding limits
if (open.fundingAmount >= Channel.MAX_FUNDING && !localFeatures.hasFeature(Features.Wumbo)) return Left(InvalidFundingAmount(open.temporaryChannelId, open.fundingAmount, nodeParams.channelConf.minFundingSatoshis(open.channelFlags.announceChannel), Channel.MAX_FUNDING))
// BOLT #2: The receiving node MUST fail the channel if: push_msat is greater than funding_satoshis * 1000.
if (open.pushAmount > open.fundingAmount) return 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.channelConf.maxToLocalDelay) return Left(ToSelfDelayTooHigh(open.temporaryChannelId, open.toSelfDelay, nodeParams.channelConf.maxToLocalDelay))
Expand Down Expand Up @@ -222,6 +223,12 @@ object Helpers {
case None => // we agree on channel type
}

// BOLT #2: Channel funding limits
if (accept.fundingAmount > nodeParams.channelConf.maxFundingSatoshis) return Left(InvalidFundingAmount(accept.temporaryChannelId, accept.fundingAmount, 0 sat, nodeParams.channelConf.maxFundingSatoshis))

// BOLT #2: The receiving node MUST fail the channel if: push_msat is greater than funding_satoshis * 1000.
if (accept.pushAmount > accept.fundingAmount) return Left(InvalidPushAmount(accept.temporaryChannelId, accept.pushAmount, accept.fundingAmount.toMilliSatoshi))

if (accept.maxAcceptedHtlcs > Channel.MAX_ACCEPTED_HTLCS) return Left(InvalidMaxAcceptedHtlcs(accept.temporaryChannelId, accept.maxAcceptedHtlcs, Channel.MAX_ACCEPTED_HTLCS))

if (accept.dustLimit < Channel.MIN_DUST_LIMIT) return Left(DustLimitTooSmall(accept.temporaryChannelId, accept.dustLimit, Channel.MIN_DUST_LIMIT))
Expand Down Expand Up @@ -402,34 +409,35 @@ object Helpers {
*/
def makeFirstCommitTxs(keyManager: ChannelKeyManager, channelConfig: ChannelConfig, channelFeatures: ChannelFeatures, temporaryChannelId: ByteVector32,
localParams: LocalParams, remoteParams: RemoteParams,
localFundingAmount: Satoshi, remoteFundingAmount: Satoshi, pushMsat: MilliSatoshi,
localFundingAmount: Satoshi, remoteFundingAmount: Satoshi,
localPushAmount: MilliSatoshi, remotePushAmount: MilliSatoshi,
commitTxFeerate: FeeratePerKw,
fundingTxHash: ByteVector32, fundingTxOutputIndex: Int,
remoteFirstPerCommitmentPoint: PublicKey): Either[ChannelException, (CommitmentSpec, CommitTx, CommitmentSpec, CommitTx)] = {
val toLocalMsat = if (localParams.isInitiator) localFundingAmount.toMilliSatoshi - pushMsat else localFundingAmount.toMilliSatoshi + pushMsat
val toRemoteMsat = if (localParams.isInitiator) remoteFundingAmount.toMilliSatoshi + pushMsat else remoteFundingAmount.toMilliSatoshi - pushMsat
val fundingAmount = localFundingAmount + remoteFundingAmount
val toLocalMsat = localFundingAmount.toMilliSatoshi - localPushAmount + remotePushAmount
val toRemoteMsat = remoteFundingAmount.toMilliSatoshi + localPushAmount - remotePushAmount

val localSpec = CommitmentSpec(Set.empty[DirectedHtlc], commitTxFeerate, toLocal = toLocalMsat, toRemote = toRemoteMsat)
val remoteSpec = CommitmentSpec(Set.empty[DirectedHtlc], commitTxFeerate, toLocal = toRemoteMsat, toRemote = toLocalMsat)

if (!localParams.isInitiator) {
// they initiated the channel open, therefore they pay the fee: we need to make sure they can afford it!
val toRemoteMsat = remoteSpec.toLocal
val fees = commitTxTotalCost(remoteParams.dustLimit, remoteSpec, channelFeatures.commitmentFormat)
val reserve = if (channelFeatures.hasFeature(Features.DualFunding)) {
((localFundingAmount + remoteFundingAmount) / 100).max(localParams.dustLimit)
(fundingAmount / 100).max(localParams.dustLimit)
} else {
localParams.requestedChannelReserve_opt.get
}
val missing = toRemoteMsat.truncateToSatoshi - reserve - fees
if (missing < Satoshi(0)) {
if (missing < 0.sat) {
return Left(CannotAffordFees(temporaryChannelId, missing = -missing, reserve = reserve, fees = fees))
}
}

val fundingPubKey = keyManager.fundingPublicKey(localParams.fundingKeyPath)
val channelKeyPath = keyManager.keyPath(localParams, channelConfig)
val commitmentInput = makeFundingInputInfo(fundingTxHash, fundingTxOutputIndex, localFundingAmount + remoteFundingAmount, fundingPubKey.publicKey, remoteParams.fundingPubKey)
val commitmentInput = makeFundingInputInfo(fundingTxHash, fundingTxOutputIndex, fundingAmount, fundingPubKey.publicKey, remoteParams.fundingPubKey)
val localPerCommitmentPoint = keyManager.commitmentPoint(channelKeyPath, 0)
val (localCommitTx, _) = Commitments.makeLocalTxs(keyManager, channelConfig, channelFeatures, 0, localParams, remoteParams, commitmentInput, localPerCommitmentPoint, localSpec)
val (remoteCommitTx, _) = Commitments.makeRemoteTxs(keyManager, channelConfig, channelFeatures, 0, localParams, remoteParams, commitmentInput, remoteFirstPerCommitmentPoint, remoteSpec)
Expand Down
10 changes: 7 additions & 3 deletions eclair-core/src/main/scala/fr/acinq/eclair/channel/InteractiveTxBuilder.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ import fr.acinq.eclair.crypto.keymanager.ChannelKeyManager
import fr.acinq.eclair.transactions.Transactions
import fr.acinq.eclair.transactions.Transactions.TxOwner
import fr.acinq.eclair.wire.protocol._
import fr.acinq.eclair.{Logs, MilliSatoshiLong, UInt64, randomKey}
import fr.acinq.eclair.{Logs, MilliSatoshi, UInt64, randomKey}
import scodec.bits.ByteVector

import scala.concurrent.{ExecutionContext, Future}
Expand Down Expand Up @@ -197,6 +197,8 @@ object InteractiveTxBuilder {
def apply(remoteNodeId: PublicKey,
fundingParams: InteractiveTxParams,
keyManager: ChannelKeyManager,
localPushAmount: MilliSatoshi,

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@pm47

pm47 Nov 17, 2022

Member

@t-bast Shouldn't those have been put in InteractiveTxParams?

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@t-bast

t-bast Nov 17, 2022

Author Member

Good question, this is subtle, but I believe it's at the right place outside of InteractiveTxParams, because push_amount only applies to the commitment transaction, not the funding transaction.
remotePushAmount: MilliSatoshi,
localParams: LocalParams,
remoteParams: RemoteParams,
commitTxFeerate: FeeratePerKw,
Expand All @@ -213,7 +215,7 @@ object InteractiveTxBuilder {
Behaviors.withMdc(Logs.mdc(remoteNodeId_opt = Some(remoteNodeId), channelId_opt = Some(fundingParams.channelId))) {
Behaviors.receiveMessagePartial {
case Start(replyTo, previousTransactions) =>
val actor = new InteractiveTxBuilder(replyTo, fundingParams, keyManager, localParams, remoteParams, commitTxFeerate, remoteFirstPerCommitmentPoint, channelFlags, channelConfig, channelFeatures, wallet, previousTransactions, stash, context)
val actor = new InteractiveTxBuilder(replyTo, fundingParams, keyManager, localPushAmount, remotePushAmount, localParams, remoteParams, commitTxFeerate, remoteFirstPerCommitmentPoint, channelFlags, channelConfig, channelFeatures, wallet, previousTransactions, stash, context)
actor.start()
case Abort => Behaviors.stopped
}
Expand Down Expand Up @@ -263,6 +265,8 @@ object InteractiveTxBuilder {
private class InteractiveTxBuilder(replyTo: ActorRef[InteractiveTxBuilder.Response],
fundingParams: InteractiveTxBuilder.InteractiveTxParams,
keyManager: ChannelKeyManager,
localPushAmount: MilliSatoshi,
remotePushAmount: MilliSatoshi,
localParams: LocalParams,
remoteParams: RemoteParams,
commitTxFeerate: FeeratePerKw,
Expand Down Expand Up @@ -701,7 +705,7 @@ private class InteractiveTxBuilder(replyTo: ActorRef[InteractiveTxBuilder.Respon

def signCommitTx(completeTx: SharedTransaction, fundingOutputIndex: Int): Behavior[Command] = {
val fundingTx = completeTx.buildUnsignedTx()
Funding.makeFirstCommitTxs(keyManager, channelConfig, channelFeatures, fundingParams.channelId, localParams, remoteParams, fundingParams.localAmount, fundingParams.remoteAmount, 0 msat, commitTxFeerate, fundingTx.hash, fundingOutputIndex, remoteFirstPerCommitmentPoint) match {
Funding.makeFirstCommitTxs(keyManager, channelConfig, channelFeatures, fundingParams.channelId, localParams, remoteParams, fundingParams.localAmount, fundingParams.remoteAmount, localPushAmount, remotePushAmount, commitTxFeerate, fundingTx.hash, fundingOutputIndex, remoteFirstPerCommitmentPoint) match {
case Left(cause) =>
replyTo ! RemoteFailure(cause)
unlockAndStop(completeTx)
Expand Down
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