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Update single funded channel to select inputs before sending open
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 - makeFundingTx now just selects inputs and change outputs
 - (new) signFundingTx replaces the funding output script and signs
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@remyers
remyers committed Aug 5, 2024
1 parent e784ee3 commit 7b8b2ae
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Showing 14 changed files with 332 additions and 94 deletions.
9 changes: 7 additions & 2 deletions eclair-core/src/main/scala/fr/acinq/eclair/blockchain/OnChainWallet.scala
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Expand Up @@ -54,10 +54,13 @@ trait OnChainChannelFunder {
*/
def publishTransaction(tx: Transaction)(implicit ec: ExecutionContext): Future[TxId]

/** Create a fully signed channel funding transaction with the provided pubkeyScript. */
/** Create an unsigned channel funding transaction with the provided dummy pubkeyScript. */
def makeFundingTx(pubkeyScript: ByteVector, amount: Satoshi, feeRate: FeeratePerKw, feeBudget_opt: Option[Satoshi], maxExcess_opt: Option[Satoshi])(implicit ec: ExecutionContext): Future[MakeFundingTxResponse]

/**
/** Sign a funding transaction with an updated pubkeyScript. */
def signFundingTx(tx: Transaction, pubkeyScript: ByteVector, outputIndex: Int, fee: Satoshi, targetFeerate: FeeratePerKw)(implicit ec: ExecutionContext): Future[SignFundingTxResponse]

/**
* Committing *must* include publishing the transaction on the network.
*
* We need to be very careful here, we don't want to consider a commit 'failed' if we are not absolutely sure that the
Expand Down Expand Up @@ -155,6 +158,8 @@ object OnChainWallet {

final case class MakeFundingTxResponse(fundingTx: Transaction, fundingTxOutputIndex: Int, fee: Satoshi)

final case class SignFundingTxResponse(fundingTx: Transaction, fundingTxOutputIndex: Int, fee: Satoshi)

final case class FundTransactionResponse(tx: Transaction, fee: Satoshi, changePosition: Option[Int]) {
val amountIn: Satoshi = fee + tx.txOut.map(_.amount).sum
}
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40 changes: 27 additions & 13 deletions eclair-core/src/main/scala/fr/acinq/eclair/blockchain/bitcoind/rpc/BitcoinCoreClient.scala
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Expand Up @@ -22,11 +22,10 @@ import fr.acinq.bitcoin.scalacompat._
import fr.acinq.bitcoin.{Bech32, Block, SigHash}
import fr.acinq.eclair.ShortChannelId.coordinates
import fr.acinq.eclair.blockchain.OnChainWallet
import fr.acinq.eclair.blockchain.OnChainWallet.{FundTransactionResponse, MakeFundingTxResponse, OnChainBalance, ProcessPsbtResponse}
import fr.acinq.eclair.blockchain.OnChainWallet.{FundTransactionResponse, MakeFundingTxResponse, OnChainBalance, ProcessPsbtResponse, SignFundingTxResponse}
import fr.acinq.eclair.blockchain.bitcoind.ZmqWatcher.{GetTxWithMetaResponse, UtxoStatus, ValidateResult}
import fr.acinq.eclair.blockchain.fee.{FeeratePerKB, FeeratePerKw}
import fr.acinq.eclair.crypto.keymanager.OnChainKeyManager
import fr.acinq.eclair.json.SatoshiSerializer
import fr.acinq.eclair.transactions.Transactions
import fr.acinq.eclair.wire.protocol.ChannelAnnouncement
import fr.acinq.eclair.{BlockHeight, TimestampSecond, TxCoordinates}
Expand Down Expand Up @@ -310,7 +309,28 @@ class BitcoinCoreClient(val rpcClient: BitcoinJsonRPCClient, val onChainKeyManag

def makeFundingTx(pubkeyScript: ByteVector, amount: Satoshi, targetFeerate: FeeratePerKw, feeBudget_opt: Option[Satoshi] = None, maxExcess_opt: Option[Satoshi] = None)(implicit ec: ExecutionContext): Future[MakeFundingTxResponse] = {

def verifyAndSign(tx: Transaction, fees: Satoshi, requestedFeeRate: FeeratePerKw): Future[MakeFundingTxResponse] = {
val partialFundingTx = Transaction(
version = 2,
txIn = Seq.empty[TxIn],
txOut = TxOut(amount, pubkeyScript) :: Nil,
lockTime = 0)

for {
// TODO: we should check that mempoolMinFee is not dangerously high
feerate <- mempoolMinFee().map(minFee => FeeratePerKw(minFee).max(targetFeerate))
// we ask bitcoin core to add inputs to the funding tx, and use the specified change address
FundTransactionResponse(tx, fee, _) <- fundTransaction(partialFundingTx, FundTransactionOptions(feerate, add_excess_to_recipient_position = None, max_excess = maxExcess_opt), feeBudget_opt = feeBudget_opt)
fundingOutputIndex = Transactions.findPubKeyScriptIndex(tx, pubkeyScript) match {
case Left(_) => return Future.failed(new RuntimeException("cannot find expected funding output: bitcoin core may be malicious"))
case Right(outputIndex) => outputIndex
}
makeFundingTxResponse = MakeFundingTxResponse(tx, fundingOutputIndex, fee)
} yield makeFundingTxResponse
}

def signFundingTx(tx: Transaction, pubkeyScript: ByteVector, outputIndex: Int, fee: Satoshi, targetFeerate: FeeratePerKw)(implicit ec: ExecutionContext): Future[SignFundingTxResponse] = {

def verifyAndSign(tx: Transaction, fees: Satoshi, requestedFeeRate: FeeratePerKw)(implicit ec: ExecutionContext): Future[SignFundingTxResponse] = {
import KotlinUtils._

val fundingOutputIndex = Transactions.findPubKeyScriptIndex(tx, pubkeyScript) match {
Expand All @@ -331,22 +351,16 @@ class BitcoinCoreClient(val rpcClient: BitcoinJsonRPCClient, val onChainKeyManag
maxFeerate = requestedFeeRate * 1.5
_ = require(actualFeerate < maxFeerate, s"actual feerate $actualFeerate is more than 50% above requested feerate $targetFeerate")
_ = logger.debug(s"created funding txid=${fundingTx.txid} outputIndex=$fundingOutputIndex fee=$fees")
} yield MakeFundingTxResponse(fundingTx, fundingOutputIndex, fees)
} yield SignFundingTxResponse(fundingTx, fundingOutputIndex, fees)
}

val partialFundingTx = Transaction(
version = 2,
txIn = Seq.empty[TxIn],
txOut = TxOut(amount, pubkeyScript) :: Nil,
lockTime = 0)
val tx1 = tx.copy(txOut = tx.txOut.updated(outputIndex, tx.txOut(outputIndex).copy(publicKeyScript = pubkeyScript)))

for {
// TODO: we should check that mempoolMinFee is not dangerously high
feerate <- mempoolMinFee().map(minFee => FeeratePerKw(minFee).max(targetFeerate))
// we ask bitcoin core to add inputs to the funding tx, and use the specified change address
FundTransactionResponse(tx, fee, _) <- fundTransaction(partialFundingTx, FundTransactionOptions(feerate, add_excess_to_recipient_position = None, max_excess = maxExcess_opt), feeBudget_opt = feeBudget_opt)
lockedUtxos = tx.txIn.map(_.outPoint)
signedTx <- unlockIfFails(lockedUtxos)(verifyAndSign(tx, fee, feerate))
lockedUtxos = tx1.txIn.map(_.outPoint)
signedTx <- unlockIfFails(lockedUtxos)(verifyAndSign(tx1, fee, feerate))
} yield signedTx
}

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19 changes: 10 additions & 9 deletions eclair-core/src/main/scala/fr/acinq/eclair/channel/ChannelData.scala
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Expand Up @@ -19,6 +19,7 @@ package fr.acinq.eclair.channel
import akka.actor.{ActorRef, PossiblyHarmful, typed}
import fr.acinq.bitcoin.scalacompat.Crypto.PublicKey
import fr.acinq.bitcoin.scalacompat.{ByteVector32, DeterministicWallet, OutPoint, Satoshi, SatoshiLong, Transaction, TxId, TxOut}
import fr.acinq.eclair.blockchain.OnChainWallet.MakeFundingTxResponse
import fr.acinq.eclair.blockchain.fee.{ConfirmationTarget, FeeratePerKw}
import fr.acinq.eclair.channel.LocalFundingStatus.DualFundedUnconfirmedFundingTx
import fr.acinq.eclair.channel.fund.InteractiveTxBuilder._
Expand Down Expand Up @@ -53,6 +54,7 @@ sealed trait ChannelState
case object WAIT_FOR_INIT_INTERNAL extends ChannelState
// Single-funder channel opening:
case object WAIT_FOR_INIT_SINGLE_FUNDED_CHANNEL extends ChannelState
case object WAIT_FOR_FUNDING_SIGNED_INTERNAL extends ChannelState
case object WAIT_FOR_OPEN_CHANNEL extends ChannelState
case object WAIT_FOR_ACCEPT_CHANNEL extends ChannelState
case object WAIT_FOR_FUNDING_INTERNAL extends ChannelState
Expand Down Expand Up @@ -522,17 +524,11 @@ sealed trait ChannelDataWithCommitments extends PersistentChannelData {
final case class DATA_WAIT_FOR_OPEN_CHANNEL(initFundee: INPUT_INIT_CHANNEL_NON_INITIATOR) extends TransientChannelData {
val channelId: ByteVector32 = initFundee.temporaryChannelId
}
final case class DATA_WAIT_FOR_ACCEPT_CHANNEL(initFunder: INPUT_INIT_CHANNEL_INITIATOR, lastSent: OpenChannel) extends TransientChannelData {
final case class DATA_WAIT_FOR_ACCEPT_CHANNEL(initFunder: INPUT_INIT_CHANNEL_INITIATOR, lastSent: OpenChannel, fundingTxResponse: MakeFundingTxResponse) extends TransientChannelData {
val channelId: ByteVector32 = initFunder.temporaryChannelId
}
final case class DATA_WAIT_FOR_FUNDING_INTERNAL(params: ChannelParams,
fundingAmount: Satoshi,
pushAmount: MilliSatoshi,
commitTxFeerate: FeeratePerKw,
remoteFundingPubKey: PublicKey,
remoteFirstPerCommitmentPoint: PublicKey,
replyTo: akka.actor.typed.ActorRef[Peer.OpenChannelResponse]) extends TransientChannelData {
val channelId: ByteVector32 = params.channelId
final case class DATA_WAIT_FOR_FUNDING_INTERNAL(input: INPUT_INIT_CHANNEL_INITIATOR) extends TransientChannelData {
val channelId: ByteVector32 = input.temporaryChannelId
}
final case class DATA_WAIT_FOR_FUNDING_CREATED(params: ChannelParams,
fundingAmount: Satoshi,
Expand Down Expand Up @@ -567,6 +563,11 @@ final case class DATA_WAIT_FOR_OPEN_DUAL_FUNDED_CHANNEL(init: INPUT_INIT_CHANNEL
final case class DATA_WAIT_FOR_ACCEPT_DUAL_FUNDED_CHANNEL(init: INPUT_INIT_CHANNEL_INITIATOR, lastSent: OpenDualFundedChannel) extends TransientChannelData {
val channelId: ByteVector32 = lastSent.temporaryChannelId
}
final case class DATA_WAIT_FOR_FUNDING_SIGNED_INTERNAL(lastFundingTx: Transaction, params: ChannelParams, fundingAmount: Satoshi,
pushAmount: MilliSatoshi, commitTxFeerate: FeeratePerKw, remoteFundingPubKey: PublicKey,
remoteFirstPerCommitmentPoint: PublicKey, replyTo: akka.actor.typed.ActorRef[Peer.OpenChannelResponse]) extends TransientChannelData {
val channelId: ByteVector32 = params.channelId
}
final case class DATA_WAIT_FOR_DUAL_FUNDING_CREATED(channelId: ByteVector32,
channelParams: ChannelParams,
secondRemotePerCommitmentPoint: PublicKey,
Expand Down
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