Add a txOut field to our InteractiveTxBuilder.Input interface (#2791)

* Add a txOut field to our InteractiveTxBuilder.Input interface

This will help us add support for taproot inputs: to create taproot signatures we need all prevouts (and not just prevouts for tx inputs that spend taproot outputs).

Author: sstone

eclair-core/src/main/scala/fr/acinq/eclair/channel/fund/InteractiveTxBuilder.scala

@@ -216,11 +216,13 @@ object InteractiveTxBuilder {
     def serialId: UInt64
     def outPoint: OutPoint
     def sequence: Long
+    def txOut: TxOut
   }
   object Input {
     /** A local-only input that funds the interactive transaction. */
     case class Local(serialId: UInt64, previousTx: Transaction, previousTxOutput: Long, sequence: Long) extends Input with Outgoing {
       override val outPoint: OutPoint = OutPoint(previousTx, previousTxOutput.toInt)
+      override def txOut: TxOut = previousTx.txOut(previousTxOutput.toInt)
     }
 
     /**
@@ -230,7 +232,9 @@ object InteractiveTxBuilder {
     case class Remote(serialId: UInt64, outPoint: OutPoint, txOut: TxOut, sequence: Long) extends Input with Incoming
 
     /** The shared input can be added by us or by our peer, depending on who initiated the protocol. */
-    case class Shared(serialId: UInt64, outPoint: OutPoint, sequence: Long, localAmount: MilliSatoshi, remoteAmount: MilliSatoshi, htlcAmount: MilliSatoshi) extends Input with Incoming with Outgoing
+    case class Shared(serialId: UInt64, outPoint: OutPoint, publicKeyScript: ByteVector, sequence: Long, localAmount: MilliSatoshi, remoteAmount: MilliSatoshi, htlcAmount: MilliSatoshi) extends Input with Incoming with Outgoing {
+      override def txOut: TxOut = TxOut((localAmount + remoteAmount + htlcAmount).truncateToSatoshi, publicKeyScript)
+    }
   }
 
   sealed trait Output {
@@ -282,7 +286,7 @@ object InteractiveTxBuilder {
                                localInputs: List[Input.Local], remoteInputs: List[Input.Remote],
                                localOutputs: List[Output.Local], remoteOutputs: List[Output.Remote],
                                lockTime: Long) {
-    val localAmountIn: MilliSatoshi = sharedInput_opt.map(_.localAmount).getOrElse(0 msat) + localInputs.map(i => i.previousTx.txOut(i.previousTxOutput.toInt).amount).sum
+    val localAmountIn: MilliSatoshi = sharedInput_opt.map(_.localAmount).getOrElse(0 msat) + localInputs.map(i => i.txOut.amount).sum
     val remoteAmountIn: MilliSatoshi = sharedInput_opt.map(_.remoteAmount).getOrElse(0 msat) + remoteInputs.map(_.txOut.amount).sum
     val localAmountOut: MilliSatoshi = sharedOutput.localAmount + localOutputs.map(_.amount).sum
     val remoteAmountOut: MilliSatoshi = sharedOutput.remoteAmount + remoteOutputs.map(_.amount).sum
@@ -489,7 +493,7 @@ private class InteractiveTxBuilder(replyTo: ActorRef[InteractiveTxBuilder.Respon
       case None =>
         (addInput.sharedInput_opt, fundingParams.sharedInput_opt) match {
           case (Some(outPoint), Some(sharedInput)) if outPoint == sharedInput.info.outPoint =>
-            Input.Shared(addInput.serialId, outPoint, addInput.sequence, purpose.previousLocalBalance, purpose.previousRemoteBalance, purpose.htlcBalance)
+            Input.Shared(addInput.serialId, outPoint, sharedInput.info.txOut.publicKeyScript, addInput.sequence, purpose.previousLocalBalance, purpose.previousRemoteBalance, purpose.htlcBalance)
           case _ =>
             return Left(PreviousTxMissing(fundingParams.channelId, addInput.serialId))
         }
@@ -810,7 +814,7 @@ private class InteractiveTxBuilder(replyTo: ActorRef[InteractiveTxBuilder.Respon
           // Partially signed PSBT must include spent amounts for all inputs that were signed, and we can "trust" these amounts because they are included
           // in the hash that we signed (see BIP143). If our bitcoin node lied about them, then our signatures are invalid.
           val actualLocalAmountIn = ourWalletInputs.map(i => kmp2scala(response.psbt.getInput(i).getWitnessUtxo.amount)).sum
-          val expectedLocalAmountIn = unsignedTx.localInputs.map(i => i.previousTx.txOut(i.previousTxOutput.toInt).amount).sum
+          val expectedLocalAmountIn = unsignedTx.localInputs.map(i => i.txOut.amount).sum
           require(actualLocalAmountIn == expectedLocalAmountIn, s"local spent amount $actualLocalAmountIn does not match what we expect ($expectedLocalAmountIn): bitcoin core may be malicious")
           val actualLocalAmountOut = ourWalletOutputs.map(i => partiallySignedTx.txOut(i).amount).sum
           val expectedLocalAmountOut = unsignedTx.localOutputs.map {
@@ -884,9 +888,9 @@ object InteractiveTxSigningSession {
   private def shouldSignFirst(isInitiator: Boolean, channelParams: ChannelParams, tx: SharedTransaction): Boolean = {
     val sharedAmountIn = tx.sharedInput_opt.map(i => i.localAmount + i.remoteAmount + i.htlcAmount).getOrElse(0 msat).truncateToSatoshi
     val (localAmountIn, remoteAmountIn) = if (isInitiator) {
-      (sharedAmountIn + tx.localInputs.map(i => i.previousTx.txOut(i.previousTxOutput.toInt).amount).sum, tx.remoteInputs.map(i => i.txOut.amount).sum)
+      (sharedAmountIn + tx.localInputs.map(i => i.txOut.amount).sum, tx.remoteInputs.map(i => i.txOut.amount).sum)
     } else {
-      (tx.localInputs.map(i => i.previousTx.txOut(i.previousTxOutput.toInt).amount).sum, sharedAmountIn + tx.remoteInputs.map(i => i.txOut.amount).sum)
+      (tx.localInputs.map(i => i.txOut.amount).sum, sharedAmountIn + tx.remoteInputs.map(i => i.txOut.amount).sum)
     }
     if (localAmountIn == remoteAmountIn) {
       // When both peers contribute the same amount, the peer with the lowest pubkey must transmit its `tx_signatures` first.
@@ -928,7 +932,7 @@ object InteractiveTxSigningSession {
     }
     val previousOutputs = {
       val sharedOutput = fundingParams.sharedInput_opt.map(sharedInput => sharedInput.info.outPoint -> sharedInput.info.txOut).toMap
-      val localOutputs = txWithSigs.tx.localInputs.map(i => i.outPoint -> i.previousTx.txOut(i.previousTxOutput.toInt)).toMap
+      val localOutputs = txWithSigs.tx.localInputs.map(i => i.outPoint -> i.txOut).toMap
       val remoteOutputs = txWithSigs.tx.remoteInputs.map(i => i.outPoint -> i.txOut).toMap
       sharedOutput ++ localOutputs ++ remoteOutputs
     }

eclair-core/src/main/scala/fr/acinq/eclair/channel/fund/InteractiveTxFunder.scala

@@ -157,7 +157,7 @@ private class InteractiveTxFunder(replyTo: ActorRef[InteractiveTxFunder.Response
       // force us to add wallet inputs. The caller may manually decrease the output amounts if it wants to actually
       // contribute to the RBF attempt.
       if (fundingParams.isInitiator) {
-        val sharedInput = fundingParams.sharedInput_opt.toSeq.map(sharedInput => Input.Shared(UInt64(0), sharedInput.info.outPoint, 0xfffffffdL, purpose.previousLocalBalance, purpose.previousRemoteBalance, purpose.htlcBalance))
+        val sharedInput = fundingParams.sharedInput_opt.toSeq.map(sharedInput => Input.Shared(UInt64(0), sharedInput.info.outPoint, sharedInput.info.txOut.publicKeyScript, 0xfffffffdL, purpose.previousLocalBalance, purpose.previousRemoteBalance, purpose.htlcBalance))
         val sharedOutput = Output.Shared(UInt64(0), fundingPubkeyScript, purpose.previousLocalBalance + fundingParams.localContribution, purpose.previousRemoteBalance + fundingParams.remoteContribution, purpose.htlcBalance)
         val nonChangeOutputs = fundingParams.localOutputs.map(txOut => Output.Local.NonChange(UInt64(0), txOut.amount, txOut.publicKeyScript))
         val fundingContributions = sortFundingContributions(fundingParams, sharedInput ++ previousWalletInputs, sharedOutput +: nonChangeOutputs)
@@ -292,7 +292,7 @@ private class InteractiveTxFunder(replyTo: ActorRef[InteractiveTxFunder.Response
       case None => fundingParams.sharedInput_opt match {
         case Some(sharedInput) if sharedInput.info.outPoint == txIn.outPoint =>
           // We don't need to validate the shared input, it comes from a valid lightning channel.
-          Future.successful(Right(Input.Shared(UInt64(0), sharedInput.info.outPoint, txIn.sequence, purpose.previousLocalBalance, purpose.previousRemoteBalance, purpose.htlcBalance)))
+          Future.successful(Right(Input.Shared(UInt64(0), sharedInput.info.outPoint, sharedInput.info.txOut.publicKeyScript, txIn.sequence, purpose.previousLocalBalance, purpose.previousRemoteBalance, purpose.htlcBalance)))
         case _ =>
           for {
             previousTx <- wallet.getTransaction(txIn.outPoint.txid)

eclair-core/src/main/scala/fr/acinq/eclair/wire/internal/channel/version4/ChannelCodecs4.scala

@@ -10,6 +10,7 @@ import fr.acinq.eclair.channel.fund.InteractiveTxSigningSession.UnsignedLocalCom
 import fr.acinq.eclair.channel.fund.{InteractiveTxBuilder, InteractiveTxSigningSession}
 import fr.acinq.eclair.crypto.ShaChain
 import fr.acinq.eclair.MilliSatoshiLong
+import fr.acinq.eclair.channel.fund.InteractiveTxBuilder.{FullySignedSharedTransaction, PartiallySignedSharedTransaction}
 import fr.acinq.eclair.transactions.Transactions._
 import fr.acinq.eclair.transactions.{CommitmentSpec, DirectedHtlc, IncomingHtlc, OutgoingHtlc}
 import fr.acinq.eclair.wire.protocol.CommonCodecs._
@@ -252,6 +253,7 @@ private[channel] object ChannelCodecs4 {
     private val sharedInteractiveTxInputWithoutHtlcsCodec: Codec[InteractiveTxBuilder.Input.Shared] = (
       ("serialId" | uint64) ::
         ("outPoint" | outPointCodec) ::
+        ("publicKeyScript" | provide(ByteVector.empty)) ::
         ("sequence" | uint32) ::
         ("localAmount" | millisatoshi) ::
         ("remoteAmount" | millisatoshi) ::
@@ -260,12 +262,23 @@ private[channel] object ChannelCodecs4 {
     private val sharedInteractiveTxInputWithHtlcsCodec: Codec[InteractiveTxBuilder.Input.Shared] = (
       ("serialId" | uint64) ::
         ("outPoint" | outPointCodec) ::
+        ("publicKeyScript" | provide(ByteVector.empty)) ::
+        ("sequence" | uint32) ::
+        ("localAmount" | millisatoshi) ::
+        ("remoteAmount" | millisatoshi) ::
+        ("htlcAmount" | millisatoshi)).as[InteractiveTxBuilder.Input.Shared]
+
+    private val sharedInteractiveTxInputWithHtlcsAndPubkeyScriptCodec: Codec[InteractiveTxBuilder.Input.Shared] = (
+      ("serialId" | uint64) ::
+        ("outPoint" | outPointCodec) ::
+        ("publicKeyScript" | lengthDelimited(bytes)) ::
         ("sequence" | uint32) ::
         ("localAmount" | millisatoshi) ::
         ("remoteAmount" | millisatoshi) ::
         ("htlcAmount" | millisatoshi)).as[InteractiveTxBuilder.Input.Shared]
 
     private val sharedInteractiveTxInputCodec: Codec[InteractiveTxBuilder.Input.Shared] = discriminated[InteractiveTxBuilder.Input.Shared].by(byte)
+      .typecase(0x03, sharedInteractiveTxInputWithHtlcsAndPubkeyScriptCodec)
       .typecase(0x02, sharedInteractiveTxInputWithHtlcsCodec)
       .typecase(0x01, sharedInteractiveTxInputWithoutHtlcsCodec)
 
@@ -355,7 +368,20 @@ private[channel] object ChannelCodecs4 {
     private val dualFundedUnconfirmedFundingTxCodec: Codec[DualFundedUnconfirmedFundingTx] = (
       ("sharedTx" | signedSharedTransactionCodec) ::
         ("createdAt" | blockHeight) ::
-        ("fundingParams" | fundingParamsCodec)).as[DualFundedUnconfirmedFundingTx]
+        ("fundingParams" | fundingParamsCodec)).as[DualFundedUnconfirmedFundingTx].xmap(
+      dfu => (dfu.sharedTx.tx.sharedInput_opt, dfu.fundingParams.sharedInput_opt) match {
+        case (Some(sharedTxInput), Some(sharedFundingParamsInput)) if sharedTxInput.publicKeyScript.isEmpty =>
+          val sharedTxInput1 = sharedTxInput.copy(publicKeyScript = sharedFundingParamsInput.info.txOut.publicKeyScript)
+          val sharedTx1 = dfu.sharedTx.tx.copy(sharedInput_opt = Some(sharedTxInput1))
+          val dfu1 = dfu.sharedTx match {
+            case pt: PartiallySignedSharedTransaction => dfu.copy(sharedTx = pt.copy(tx = sharedTx1))
+            case ft: FullySignedSharedTransaction => dfu.copy(sharedTx = ft.copy(tx = sharedTx1))
+          }
+          dfu1
+        case _ => dfu
+      },
+      dfu => dfu
+    )
 
     val fundingTxStatusCodec: Codec[LocalFundingStatus] = discriminated[LocalFundingStatus].by(uint8)
       .typecase(0x01, optional(bool8, txCodec).as[SingleFundedUnconfirmedFundingTx])

eclair-core/src/test/scala/fr/acinq/eclair/wire/internal/channel/version4/ChannelCodecs4Spec.scala

@@ -1,22 +1,24 @@
 package fr.acinq.eclair.wire.internal.channel.version4
 
 import com.softwaremill.quicklens.ModifyPimp
-import fr.acinq.bitcoin.scalacompat.{DeterministicWallet, OutPoint, Satoshi, SatoshiLong, Script, Transaction, TxIn, TxOut}
+import fr.acinq.bitcoin.scalacompat.Crypto.PrivateKey
+import fr.acinq.bitcoin.scalacompat.{ByteVector32, DeterministicWallet, OutPoint, Satoshi, SatoshiLong, Script, Transaction, TxId, TxIn, TxOut}
 import fr.acinq.eclair.FeatureSupport.{Mandatory, Optional}
 import fr.acinq.eclair.Features.{ChannelRangeQueries, PaymentSecret, VariableLengthOnion}
 import fr.acinq.eclair.TestUtils.randomTxId
-import fr.acinq.eclair.blockchain.fee.FeeratePerKw
+import fr.acinq.eclair.blockchain.fee.{FeeratePerByte, FeeratePerKw}
+import fr.acinq.eclair.channel.LocalFundingStatus.DualFundedUnconfirmedFundingTx
 import fr.acinq.eclair.channel._
 import fr.acinq.eclair.channel.fund.InteractiveTxBuilder.{InteractiveTxParams, PartiallySignedSharedTransaction, RequireConfirmedInputs, SharedTransaction}
 import fr.acinq.eclair.channel.fund.InteractiveTxSigningSession.UnsignedLocalCommit
 import fr.acinq.eclair.channel.fund.{InteractiveTxBuilder, InteractiveTxSigningSession}
-import fr.acinq.eclair.transactions.CommitmentSpec
 import fr.acinq.eclair.transactions.Transactions.{CommitTx, InputInfo}
+import fr.acinq.eclair.transactions.{CommitmentSpec, Scripts}
 import fr.acinq.eclair.wire.internal.channel.ChannelCodecsSpec.normal
-import fr.acinq.eclair.wire.internal.channel.version4.ChannelCodecs4.Codecs.{channelConfigCodec, localParamsCodec, rbfStatusCodec, remoteParamsCodec}
+import fr.acinq.eclair.wire.internal.channel.version4.ChannelCodecs4.Codecs._
 import fr.acinq.eclair.wire.internal.channel.version4.ChannelCodecs4.channelDataCodec
 import fr.acinq.eclair.wire.protocol.TxSignatures
-import fr.acinq.eclair.{CltvExpiryDelta, Features, MilliSatoshi, MilliSatoshiLong, UInt64, randomBytes32, randomKey}
+import fr.acinq.eclair.{BlockHeight, CltvExpiryDelta, Features, MilliSatoshi, MilliSatoshiLong, UInt64, randomBytes32, randomKey}
 import org.scalatest.funsuite.AnyFunSuite
 import scodec.bits._
 
@@ -154,4 +156,34 @@ class ChannelCodecs4Spec extends AnyFunSuite {
     }
   }
 
+  test("decode unconfirmed dual funded") {
+    // data encoded with the previous version of eclair, when Shared.Input did not include a pubkey script
+    val raw = ByteVector.fromValidHex("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")
+    val decoded = fundingTxStatusCodec.decode(raw.bits).require.value.asInstanceOf[LocalFundingStatus.DualFundedUnconfirmedFundingTx]
+
+    // check that our codec will set the pubkeyscript using the one from the funding params
+    val channelId = ByteVector32.Zeroes
+    val script = Scripts.multiSig2of2(PrivateKey(ByteVector.fromValidHex("01" * 32)).publicKey, PrivateKey(ByteVector.fromValidHex("02" * 32)).publicKey)
+    val dualFundedUnconfirmedFundingTx = DualFundedUnconfirmedFundingTx(
+      PartiallySignedSharedTransaction(
+        SharedTransaction(
+          // we include the correct pubkey script here
+          Some(InteractiveTxBuilder.Input.Shared(UInt64(42), OutPoint(TxId(ByteVector32.Zeroes), 0), Script.write(Script.pay2wsh(script)), 12345L, MilliSatoshi(100), MilliSatoshi(200), MilliSatoshi(300))),
+          sharedOutput = InteractiveTxBuilder.Output.Shared(UInt64(43), ByteVector.fromValidHex("deadbeef"), MilliSatoshi(100), MilliSatoshi(200), MilliSatoshi(300)),
+          localInputs = Nil, remoteInputs = Nil, localOutputs = Nil, remoteOutputs = Nil, lockTime = 0
+        ),
+        localSigs = TxSignatures(channelId, TxId(ByteVector32.Zeroes), Nil)
+      ),
+      createdAt = BlockHeight(1000),
+      fundingParams = InteractiveTxParams(channelId = channelId, isInitiator = true, localContribution = 100.sat, remoteContribution = 200.sat,
+        sharedInput_opt = Some(InteractiveTxBuilder.Multisig2of2Input(
+          InputInfo(OutPoint(TxId(ByteVector32.Zeroes), 0), TxOut(1000.sat, Script.pay2wsh(script)), script),
+          0,
+          PrivateKey(ByteVector.fromValidHex("02" * 32)).publicKey
+        )),
+        remoteFundingPubKey = PrivateKey(ByteVector.fromValidHex("01" * 32)).publicKey,
+        localOutputs = Nil, lockTime = 0, dustLimit = 330.sat, targetFeerate = FeeratePerKw(FeeratePerByte(3.sat)), requireConfirmedInputs = RequireConfirmedInputs(false, false))
+    )
+    assert(decoded == dualFundedUnconfirmedFundingTx)
+  }
 }