Use official feature bit for option_simple_taproot

Use the official feature bit and name for taproot channels and the
corresponding channel types. Activate taproot channels support by
default (without support for announcing such channels yet).

Author: t-bast

docs/release-notes/eclair-vnext.md

@@ -4,7 +4,27 @@
 
 ## Major changes
 
-<insert changes>
+### Taproot Channels (without announcements)
+
+This release adds support for taproot channels, as specified in [the BOLTs](https://github.com/lightning/bolts/pull/995).
+Taproot channels improve privacy and cost less on-chain fees by using musig2 for the channel output.
+This release is fully compatible with the `lnd` implementation of taproot channels.
+
+We don't support public taproot channels yet, as the gossip mechanism for this isn't finalized yet.
+It is thus only possible to open "private" (unannounced) taproot channels.
+You may follow progress on the specification for public taproot channels [here](https://github.com/lightning/bolts/pull/1059).
+
+This feature is active by default. To disable it, add the following to your `eclair.conf`:
+
+```conf
+eclair.features.option_simple_taproot = disabled
+```
+
+To open a taproot channel with a node that supports the `option_simple_taproot` feature, use the following command:
+
+```sh
+$ eclair-cli open --nodeId=<node_id> --fundingSatoshis=<funding_amount> --channelType=simple_taproot_channel --announceChannel=false
+```
 
 ### Remove support for legacy channel codecs
 

eclair-core/src/main/resources/reference.conf

@@ -87,7 +87,8 @@ eclair {
     // node that you trust using override-init-features (see below).
     option_zeroconf = disabled
     keysend = disabled
-    option_simple_close=optional
+    option_simple_close = optional
+    option_simple_taproot = optional
     trampoline_payment_prototype = disabled
     async_payment_prototype = disabled
     on_the_fly_funding = disabled

eclair-core/src/main/scala/fr/acinq/eclair/Features.scala

@@ -312,6 +312,11 @@ object Features {
     val mandatory = 60
   }
 
+  case object SimpleTaprootChannels extends Feature with InitFeature with NodeFeature with ChannelTypeFeature {
+    val rfcName = "option_simple_taproot"
+    val mandatory = 80
+  }
+
   /** This feature bit indicates that the node is a mobile wallet that can be woken up via push notifications. */
   case object WakeUpNotificationClient extends Feature with InitFeature {
     val rfcName = "wake_up_notification_client"
@@ -346,11 +351,6 @@ object Features {
     val mandatory = 564
   }
 
-  case object SimpleTaprootChannelsStaging extends Feature with InitFeature with NodeFeature with ChannelTypeFeature {
-    val rfcName = "option_simple_taproot_staging"
-    val mandatory = 180
-  }
-
   /**
    * Activate this feature to provide on-the-fly funding to remote nodes, as specified in bLIP 36: https://github.com/lightning/blips/blob/master/blip-0036.md.
    * TODO: add NodeFeature once bLIP is merged.
@@ -394,8 +394,8 @@ object Features {
     ZeroConf,
     KeySend,
     SimpleClose,
+    SimpleTaprootChannels,
     SimpleTaprootChannelsPhoenix,
-    SimpleTaprootChannelsStaging,
     WakeUpNotificationClient,
     TrampolinePaymentPrototype,
     AsyncPaymentPrototype,
@@ -415,6 +415,7 @@ object Features {
     TrampolinePaymentPrototype -> (PaymentSecret :: Nil),
     KeySend -> (VariableLengthOnion :: Nil),
     SimpleClose -> (ShutdownAnySegwit :: Nil),
+    SimpleTaprootChannels -> (ChannelType :: SimpleClose :: Nil),
     SimpleTaprootChannelsPhoenix -> (ChannelType :: SimpleClose :: Nil),
     AsyncPaymentPrototype -> (TrampolinePaymentPrototype :: Nil),
     OnTheFlyFunding -> (SplicePrototype :: Nil),

eclair-core/src/main/scala/fr/acinq/eclair/channel/ChannelFeatures.scala

@@ -118,27 +118,25 @@ object ChannelTypes {
     override def commitmentFormat: CommitmentFormat = ZeroFeeHtlcTxAnchorOutputsCommitmentFormat
     override def toString: String = s"anchor_outputs_zero_fee_htlc_tx${if (scidAlias) "+scid_alias" else ""}${if (zeroConf) "+zeroconf" else ""}"
   }
-  case class SimpleTaprootChannelsPhoenix(scidAlias: Boolean = false, zeroConf: Boolean = false) extends SupportedChannelType {
-    /** Known channel-type features */
+  case class SimpleTaprootChannel(scidAlias: Boolean = false, zeroConf: Boolean = false) extends SupportedChannelType {
     override def features: Set[ChannelTypeFeature] = Set(
       if (scidAlias) Some(Features.ScidAlias) else None,
       if (zeroConf) Some(Features.ZeroConf) else None,
-      Some(Features.SimpleTaprootChannelsPhoenix),
+      Some(Features.SimpleTaprootChannels),
     ).flatten
     override def paysDirectlyToWallet: Boolean = false
-    override def commitmentFormat: CommitmentFormat = PhoenixSimpleTaprootChannelCommitmentFormat
-    override def toString: String = s"simple_taproot_channel_phoenix${if (scidAlias) "+scid_alias" else ""}${if (zeroConf) "+zeroconf" else ""}"
+    override def commitmentFormat: CommitmentFormat = ZeroFeeHtlcTxSimpleTaprootChannelCommitmentFormat
+    override def toString: String = s"simple_taproot_channel${if (scidAlias) "+scid_alias" else ""}${if (zeroConf) "+zeroconf" else ""}"
   }
-  case class SimpleTaprootChannelsStaging(scidAlias: Boolean = false, zeroConf: Boolean = false) extends SupportedChannelType {
-    /** Known channel-type features */
+  case class SimpleTaprootChannelPhoenix(scidAlias: Boolean = false, zeroConf: Boolean = false) extends SupportedChannelType {
     override def features: Set[ChannelTypeFeature] = Set(
       if (scidAlias) Some(Features.ScidAlias) else None,
       if (zeroConf) Some(Features.ZeroConf) else None,
-      Some(Features.SimpleTaprootChannelsStaging),
+      Some(Features.SimpleTaprootChannelsPhoenix),
     ).flatten
     override def paysDirectlyToWallet: Boolean = false
-    override def commitmentFormat: CommitmentFormat = ZeroFeeHtlcTxSimpleTaprootChannelCommitmentFormat
-    override def toString: String = s"simple_taproot_channel_staging${if (scidAlias) "+scid_alias" else ""}${if (zeroConf) "+zeroconf" else ""}"
+    override def commitmentFormat: CommitmentFormat = PhoenixSimpleTaprootChannelCommitmentFormat
+    override def toString: String = s"simple_taproot_channel_phoenix${if (scidAlias) "+scid_alias" else ""}${if (zeroConf) "+zeroconf" else ""}"
   }
 
   case class UnsupportedChannelType(featureBits: Features[InitFeature]) extends ChannelType {
@@ -164,17 +162,17 @@ object ChannelTypes {
     AnchorOutputsZeroFeeHtlcTx(zeroConf = true),
     AnchorOutputsZeroFeeHtlcTx(scidAlias = true),
     AnchorOutputsZeroFeeHtlcTx(scidAlias = true, zeroConf = true),
-    SimpleTaprootChannelsPhoenix(),
-    SimpleTaprootChannelsPhoenix(zeroConf = true),
-    SimpleTaprootChannelsPhoenix(scidAlias = true),
-    SimpleTaprootChannelsPhoenix(scidAlias = true, zeroConf = true),
-    SimpleTaprootChannelsStaging(),
-    SimpleTaprootChannelsStaging(zeroConf = true),
-    SimpleTaprootChannelsStaging(scidAlias = true),
-    SimpleTaprootChannelsStaging(scidAlias = true, zeroConf = true),
-  )
-    .map(channelType => Features(channelType.features.map(_ -> FeatureSupport.Mandatory).toMap) -> channelType)
-    .toMap
+    SimpleTaprootChannel(),
+    SimpleTaprootChannel(zeroConf = true),
+    SimpleTaprootChannel(scidAlias = true),
+    SimpleTaprootChannel(scidAlias = true, zeroConf = true),
+    SimpleTaprootChannelPhoenix(),
+    SimpleTaprootChannelPhoenix(zeroConf = true),
+    SimpleTaprootChannelPhoenix(scidAlias = true),
+    SimpleTaprootChannelPhoenix(scidAlias = true, zeroConf = true),
+  ).map {
+    channelType => Features(channelType.features.map(_ -> FeatureSupport.Mandatory).toMap) -> channelType
+  }.toMap
 
   // NB: Bolt 2: features must exactly match in order to identify a channel type.
   def fromFeatures(features: Features[InitFeature]): ChannelType = features2ChannelType.getOrElse(features, UnsupportedChannelType(features))
@@ -185,10 +183,10 @@ object ChannelTypes {
 
     val scidAlias = canUse(Features.ScidAlias) && !announceChannel // alias feature is incompatible with public channel
     val zeroConf = canUse(Features.ZeroConf)
-    if (canUse(Features.SimpleTaprootChannelsStaging)) {
-      SimpleTaprootChannelsStaging(scidAlias, zeroConf)
+    if (canUse(Features.SimpleTaprootChannels)) {
+      SimpleTaprootChannel(scidAlias, zeroConf)
     } else if (canUse(Features.SimpleTaprootChannelsPhoenix)) {
-      SimpleTaprootChannelsPhoenix(scidAlias, zeroConf)
+      SimpleTaprootChannelPhoenix(scidAlias, zeroConf)
     } else if (canUse(Features.AnchorOutputsZeroFeeHtlcTx)) {
       AnchorOutputsZeroFeeHtlcTx(scidAlias, zeroConf)
     } else if (canUse(Features.AnchorOutputs)) {

eclair-core/src/main/scala/fr/acinq/eclair/channel/fsm/Channel.scala

@@ -1113,7 +1113,7 @@ class Channel(val nodeParams: NodeParams, val channelKeys: ChannelKeys, val wall
                 // We only support updating phoenix channels to taproot: we ignore other attempts at upgrading the
                 // commitment format and will simply apply the previous commitment format.
                 val nextCommitmentFormat = msg.channelType_opt match {
-                  case Some(channelType: ChannelTypes.SimpleTaprootChannelsPhoenix) if parentCommitment.commitmentFormat == UnsafeLegacyAnchorOutputsCommitmentFormat =>
+                  case Some(channelType: ChannelTypes.SimpleTaprootChannelPhoenix) if parentCommitment.commitmentFormat == UnsafeLegacyAnchorOutputsCommitmentFormat =>
                     log.info(s"accepting upgrade to $channelType during splice from commitment format ${parentCommitment.commitmentFormat}")
                     PhoenixSimpleTaprootChannelCommitmentFormat
                   case Some(channelType) =>
@@ -1181,7 +1181,7 @@ class Channel(val nodeParams: NodeParams, val channelKeys: ChannelKeys, val wall
           // We only support updating phoenix channels to taproot: we ignore other attempts at upgrading the
           // commitment format and will simply apply the previous commitment format.
           val nextCommitmentFormat = msg.channelType_opt match {
-            case Some(_: ChannelTypes.SimpleTaprootChannelsPhoenix) if parentCommitment.commitmentFormat == UnsafeLegacyAnchorOutputsCommitmentFormat => PhoenixSimpleTaprootChannelCommitmentFormat
+            case Some(_: ChannelTypes.SimpleTaprootChannelPhoenix) if parentCommitment.commitmentFormat == UnsafeLegacyAnchorOutputsCommitmentFormat => PhoenixSimpleTaprootChannelCommitmentFormat
             case _ => parentCommitment.commitmentFormat
           }
           val fundingParams = InteractiveTxParams(

eclair-core/src/test/scala/fr/acinq/eclair/channel/InteractiveTxBuilderSpec.scala

@@ -479,7 +479,7 @@ class InteractiveTxBuilderSpec extends TestKitBaseClass with AnyFunSuiteLike wit
     val targetFeerate = FeeratePerKw(2500 sat)
     val fundingA = 150_000 sat
     val utxosA = Seq(80_000 sat, 120_000 sat)
-    withFixture(ChannelTypes.SimpleTaprootChannelsStaging(), fundingA, utxosA, 0 sat, Nil, targetFeerate, 660 sat, 0, RequireConfirmedInputs(forLocal = false, forRemote = false)) { f =>
+    withFixture(ChannelTypes.SimpleTaprootChannel(), fundingA, utxosA, 0 sat, Nil, targetFeerate, 660 sat, 0, RequireConfirmedInputs(forLocal = false, forRemote = false)) { f =>
       import f._
 
       alice ! Start(alice2bob.ref)
@@ -825,7 +825,7 @@ class InteractiveTxBuilderSpec extends TestKitBaseClass with AnyFunSuiteLike wit
     val utxosA = Seq(150_000 sat)
     val fundingB1 = 90_000 sat
     val utxosB = Seq(130_000 sat)
-    withFixture(ChannelTypes.SimpleTaprootChannelsPhoenix(), fundingA1, utxosA, fundingB1, utxosB, FeeratePerKw(1000 sat), 660 sat, 0, RequireConfirmedInputs(forLocal = true, forRemote = true)) { f =>
+    withFixture(ChannelTypes.SimpleTaprootChannelPhoenix(), fundingA1, utxosA, fundingB1, utxosB, FeeratePerKw(1000 sat), 660 sat, 0, RequireConfirmedInputs(forLocal = true, forRemote = true)) { f =>
       import f._
 
       val probe = TestProbe()
@@ -1996,7 +1996,7 @@ class InteractiveTxBuilderSpec extends TestKitBaseClass with AnyFunSuiteLike wit
     val utxosA = Seq(340_000 sat, 40_000 sat, 35_000 sat)
     val fundingB1 = 80_000 sat
     val utxosB = Seq(290_000 sat, 20_000 sat, 15_000 sat)
-    withFixture(ChannelTypes.SimpleTaprootChannelsStaging(), fundingA1, utxosA, fundingB1, utxosB, targetFeerate, 660 sat, 0, RequireConfirmedInputs(forLocal = false, forRemote = false)) { f =>
+    withFixture(ChannelTypes.SimpleTaprootChannel(), fundingA1, utxosA, fundingB1, utxosB, targetFeerate, 660 sat, 0, RequireConfirmedInputs(forLocal = false, forRemote = false)) { f =>
       import f._
 
       val probe = TestProbe()
@@ -2384,7 +2384,7 @@ class InteractiveTxBuilderSpec extends TestKitBaseClass with AnyFunSuiteLike wit
   }
 
   test("invalid tx_signatures (missing shared input signature, taproot)") {
-    testTxSignaturesMissingSharedInputSigs(ChannelTypes.SimpleTaprootChannelsStaging())
+    testTxSignaturesMissingSharedInputSigs(ChannelTypes.SimpleTaprootChannel())
   }
 
   test("invalid commitment index") {
@@ -2934,7 +2934,7 @@ class InteractiveTxBuilderSpec extends TestKitBaseClass with AnyFunSuiteLike wit
   test("invalid commit_sig (taproot)") {
     val (alice2bob, bob2alice) = (TestProbe(), TestProbe())
     val wallet = new SingleKeyOnChainWallet()
-    val params = createFixtureParams(ChannelTypes.SimpleTaprootChannelsPhoenix(), 100_000 sat, 25_000 sat, FeeratePerKw(5000 sat), 330 sat, 0)
+    val params = createFixtureParams(ChannelTypes.SimpleTaprootChannelPhoenix(), 100_000 sat, 25_000 sat, FeeratePerKw(5000 sat), 330 sat, 0)
     val alice = params.spawnTxBuilderAlice(wallet)
     val bob = params.spawnTxBuilderBob(wallet)
     alice ! Start(alice2bob.ref)

eclair-core/src/test/scala/fr/acinq/eclair/channel/states/ChannelStateTestsHelperMethods.scala

@@ -273,8 +273,8 @@ trait ChannelStateTestsBase extends Assertions with Eventually {
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ScidAlias))(_.updated(Features.ScidAlias, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.DualFunding))(_.updated(Features.DualFunding, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.SimpleClose))(_.updated(Features.SimpleClose, FeatureSupport.Optional))
+      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaproot))(_.updated(Features.SimpleTaprootChannels, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaprootPhoenix))(_.updated(Features.SimpleTaprootChannelsPhoenix, FeatureSupport.Optional))
-      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaproot))(_.updated(Features.SimpleTaprootChannelsStaging, FeatureSupport.Optional))
     )
     val nodeParamsB1 = nodeParamsB.copy(features = nodeParamsB.features
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.DisableWumbo))(_.removed(Features.Wumbo))
@@ -288,8 +288,8 @@ trait ChannelStateTestsBase extends Assertions with Eventually {
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.DualFunding))(_.updated(Features.DualFunding, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.SimpleClose))(_.updated(Features.SimpleClose, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.DisableSplice))(_.removed(Features.SplicePrototype))
+      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaproot))(_.updated(Features.SimpleTaprootChannels, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaprootPhoenix))(_.updated(Features.SimpleTaprootChannelsPhoenix, FeatureSupport.Optional))
-      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionSimpleTaproot))(_.updated(Features.SimpleTaprootChannelsStaging, FeatureSupport.Optional))
     )
     (nodeParamsA1, nodeParamsB1)
   }

eclair-core/src/test/scala/fr/acinq/eclair/channel/states/a/WaitForAcceptChannelStateSpec.scala

@@ -111,7 +111,7 @@ class WaitForAcceptChannelStateSpec extends TestKitBaseClass with FixtureAnyFunS
   test("recv AcceptChannel (simple taproot channels phoenix)", Tag(ChannelStateTestsTags.OptionSimpleTaprootPhoenix)) { f =>
     import f._
     val accept = bob2alice.expectMsgType[AcceptChannel]
-    assert(accept.channelType_opt.contains(ChannelTypes.SimpleTaprootChannelsPhoenix()))
+    assert(accept.channelType_opt.contains(ChannelTypes.SimpleTaprootChannelPhoenix()))
     assert(accept.commitNonce_opt.isDefined)
     bob2alice.forward(alice)
     awaitCond(alice.stateName == WAIT_FOR_FUNDING_INTERNAL)
@@ -122,7 +122,7 @@ class WaitForAcceptChannelStateSpec extends TestKitBaseClass with FixtureAnyFunS
   test("recv AcceptChannel (simple taproot channels outputs, missing nonce)", Tag(ChannelStateTestsTags.OptionSimpleTaprootPhoenix)) { f =>
     import f._
     val accept = bob2alice.expectMsgType[AcceptChannel]
-    assert(accept.channelType_opt.contains(ChannelTypes.SimpleTaprootChannelsPhoenix()))
+    assert(accept.channelType_opt.contains(ChannelTypes.SimpleTaprootChannelPhoenix()))
     assert(accept.commitNonce_opt.isDefined)
     bob2alice.forward(alice, accept.copy(tlvStream = accept.tlvStream.copy(records = accept.tlvStream.records.filterNot(_.isInstanceOf[ChannelTlv.NextLocalNonceTlv]))))
     alice2bob.expectMsg(Error(accept.temporaryChannelId, MissingCommitNonce(accept.temporaryChannelId, TxId(ByteVector32.Zeroes), 0).getMessage))

eclair-core/src/test/scala/fr/acinq/eclair/channel/states/a/WaitForOpenChannelStateSpec.scala

@@ -110,7 +110,7 @@ class WaitForOpenChannelStateSpec extends TestKitBaseClass with FixtureAnyFunSui
   test("recv OpenChannel (simple taproot channels)", Tag(ChannelStateTestsTags.OptionSimpleTaproot)) { f =>
     import f._
     val open = alice2bob.expectMsgType[OpenChannel]
-    assert(open.channelType_opt.contains(ChannelTypes.SimpleTaprootChannelsStaging()))
+    assert(open.channelType_opt.contains(ChannelTypes.SimpleTaprootChannel()))
     alice2bob.forward(bob)
     awaitCond(bob.stateName == WAIT_FOR_FUNDING_CREATED)
     assert(bob.stateData.asInstanceOf[DATA_WAIT_FOR_FUNDING_CREATED].commitmentFormat == ZeroFeeHtlcTxSimpleTaprootChannelCommitmentFormat)
@@ -120,7 +120,7 @@ class WaitForOpenChannelStateSpec extends TestKitBaseClass with FixtureAnyFunSui
   test("recv OpenChannel (simple taproot channels, missing nonce)", Tag(ChannelStateTestsTags.OptionSimpleTaproot)) { f =>
     import f._
     val open = alice2bob.expectMsgType[OpenChannel]
-    assert(open.channelType_opt.contains(ChannelTypes.SimpleTaprootChannelsStaging()))
+    assert(open.channelType_opt.contains(ChannelTypes.SimpleTaprootChannel()))
     assert(open.commitNonce_opt.isDefined)
     alice2bob.forward(bob, open.copy(tlvStream = open.tlvStream.copy(records = open.tlvStream.records.filterNot(_.isInstanceOf[ChannelTlv.NextLocalNonceTlv]))))
     val error = bob2alice.expectMsgType[Error]