Add channel type feature bit (#2073)

We already support channel types, but we make it explicit with a feature
bit as required by lightning/bolts#906

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

@@ -57,6 +57,7 @@ eclair {
     option_anchors_zero_fee_htlc_tx = disabled
     option_shutdown_anysegwit = optional
     option_onion_messages = disabled
+    option_channel_type = optional
     trampoline_payment = disabled
     keysend = disabled
   }

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

@@ -208,6 +208,11 @@ object Features {
     val mandatory = 38
   }
 
+  case object ChannelType extends Feature {
+    val rfcName = "option_channel_type"
+    val mandatory = 44
+  }
+
   // TODO: @t-bast: update feature bits once spec-ed (currently reserved here: https://github.com/lightningnetwork/lightning-rfc/issues/605)
   // We're not advertising these bits yet in our announcements, clients have to assume support.
   // This is why we haven't added them yet to `areSupported`.
@@ -231,12 +236,13 @@ object Features {
     PaymentSecret,
     BasicMultiPartPayment,
     Wumbo,
-    TrampolinePayment,
     StaticRemoteKey,
     AnchorOutputs,
     AnchorOutputsZeroFeeHtlcTx,
     ShutdownAnySegwit,
     OnionMessages,
+    ChannelType,
+    TrampolinePayment,
     KeySend
   )
 

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

@@ -265,6 +265,7 @@ object NodeParams extends Logging {
       require(features.hasFeature(Features.VariableLengthOnion, Some(FeatureSupport.Mandatory)), s"${Features.VariableLengthOnion.rfcName} must be enabled and mandatory")
       require(features.hasFeature(Features.PaymentSecret, Some(FeatureSupport.Mandatory)), s"${Features.PaymentSecret.rfcName} must be enabled and mandatory")
       require(!features.hasFeature(Features.InitialRoutingSync), s"${Features.InitialRoutingSync.rfcName} is not supported anymore, use ${Features.ChannelRangeQueries.rfcName} instead")
+      require(features.hasFeature(Features.ChannelType), s"${Features.ChannelType.rfcName} must be enabled")
     }
 
     val pluginMessageParams = pluginParams.collect { case p: CustomFeaturePlugin => p }

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

@@ -41,6 +41,7 @@ case class InvalidFundingAmount                    (override val channelId: Byte
 case class InvalidPushAmount                       (override val channelId: ByteVector32, pushAmount: MilliSatoshi, max: MilliSatoshi) extends ChannelException(channelId, s"invalid pushAmount=$pushAmount (max=$max)")
 case class InvalidMaxAcceptedHtlcs                 (override val channelId: ByteVector32, maxAcceptedHtlcs: Int, max: Int) extends ChannelException(channelId, s"invalid max_accepted_htlcs=$maxAcceptedHtlcs (max=$max)")
 case class InvalidChannelType                      (override val channelId: ByteVector32, ourChannelType: ChannelType, theirChannelType: ChannelType) extends ChannelException(channelId, s"invalid channel_type=$theirChannelType, expected channel_type=$ourChannelType")
+case class MissingChannelType                      (override val channelId: ByteVector32) extends ChannelException(channelId, "option_channel_type was negotiated but channel_type is missing")
 case class DustLimitTooSmall                       (override val channelId: ByteVector32, dustLimit: Satoshi, min: Satoshi) extends ChannelException(channelId, s"dustLimit=$dustLimit is too small (min=$min)")
 case class DustLimitTooLarge                       (override val channelId: ByteVector32, dustLimit: Satoshi, max: Satoshi) extends ChannelException(channelId, s"dustLimit=$dustLimit is too large (max=$max)")
 case class DustLimitAboveOurChannelReserve         (override val channelId: ByteVector32, dustLimit: Satoshi, channelReserve: Satoshi) extends ChannelException(channelId, s"dustLimit=$dustLimit is above our channelReserve=$channelReserve")

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

@@ -156,13 +156,16 @@ object Helpers {
    */
   def validateParamsFunder(nodeParams: NodeParams, channelType: SupportedChannelType, localFeatures: Features, remoteFeatures: Features, open: OpenChannel, accept: AcceptChannel): Either[ChannelException, (ChannelFeatures, Option[ByteVector])] = {
     accept.channelType_opt match {
+      case Some(theirChannelType) if accept.channelType_opt != open.channelType_opt =>
+        // if channel_type is set, and channel_type was set in open_channel, and they are not equal types: MUST reject the channel.
+        return Left(InvalidChannelType(open.temporaryChannelId, channelType, theirChannelType))
+      case None if Features.canUseFeature(localFeatures, remoteFeatures, Features.ChannelType) =>
+        // Bolt 2: if `option_channel_type` is negotiated: MUST set `channel_type`
+        return Left(MissingChannelType(open.temporaryChannelId))
       case None if channelType != ChannelTypes.defaultFromFeatures(localFeatures, remoteFeatures) =>
         // If we have overridden the default channel type, but they didn't support explicit channel type negotiation,
         // we need to abort because they expect a different channel type than what we offered.
         return Left(InvalidChannelType(open.temporaryChannelId, channelType, ChannelTypes.defaultFromFeatures(localFeatures, remoteFeatures)))
-      case Some(theirChannelType) if accept.channelType_opt != open.channelType_opt =>
-        // if channel_type is set, and channel_type was set in open_channel, and they are not equal types: MUST reject the channel.
-        return Left(InvalidChannelType(open.temporaryChannelId, channelType, theirChannelType))
       case _ => // we agree on channel type
     }
 

eclair-core/src/main/scala/fr/acinq/eclair/io/Peer.scala

@@ -157,14 +157,16 @@ class Peer(val nodeParams: NodeParams, remoteNodeId: PublicKey, wallet: OnChainA
         d.channels.get(TemporaryChannelId(msg.temporaryChannelId)) match {
           case None =>
             val channelConfig = ChannelConfig.standard
-            val chosenChannelType: Either[InvalidChannelType, SupportedChannelType] = msg.channelType_opt match {
-              // remote doesn't specify a channel type: we use spec-defined defaults
-              case None => Right(ChannelTypes.defaultFromFeatures(d.localFeatures, d.remoteFeatures))
-              // remote explicitly specifies a channel type: we negotiate
+            val chosenChannelType: Either[ChannelException, SupportedChannelType] = msg.channelType_opt match {
+              // remote explicitly specifies a channel type: we check whether we want to allow it
               case Some(remoteChannelType) => ChannelTypes.areCompatible(d.localFeatures, remoteChannelType) match {
                 case Some(acceptedChannelType) => Right(acceptedChannelType)
                 case None => Left(InvalidChannelType(msg.temporaryChannelId, ChannelTypes.defaultFromFeatures(d.localFeatures, d.remoteFeatures), remoteChannelType))
               }
+              // Bolt 2: if `option_channel_type` is negotiated: MUST set `channel_type`
+              case None if Features.canUseFeature(d.localFeatures, d.remoteFeatures, Features.ChannelType) => Left(MissingChannelType(msg.temporaryChannelId))
+              // remote doesn't specify a channel type: we use spec-defined defaults
+              case None => Right(ChannelTypes.defaultFromFeatures(d.localFeatures, d.remoteFeatures))
             }
             chosenChannelType match {
               case Right(channelType) =>

eclair-core/src/test/scala/fr/acinq/eclair/StartupSpec.scala

@@ -19,7 +19,7 @@ package fr.acinq.eclair
 import com.typesafe.config.{Config, ConfigFactory}
 import fr.acinq.bitcoin.Crypto.PublicKey
 import fr.acinq.bitcoin.{Block, SatoshiLong}
-import fr.acinq.eclair.FeatureSupport.Mandatory
+import fr.acinq.eclair.FeatureSupport.{Mandatory, Optional}
 import fr.acinq.eclair.Features._
 import fr.acinq.eclair.blockchain.fee.{DustTolerance, FeeratePerByte, FeeratePerKw, FeerateTolerance}
 import fr.acinq.eclair.crypto.keymanager.{LocalChannelKeyManager, LocalNodeKeyManager}
@@ -94,51 +94,71 @@ class StartupSpec extends AnyFunSuite {
       s"features.${OptionDataLossProtect.rfcName}" -> "optional",
       s"features.${ChannelRangeQueries.rfcName}" -> "optional",
       s"features.${ChannelRangeQueriesExtended.rfcName}" -> "optional",
+      s"features.${ChannelType.rfcName}" -> "optional",
       s"features.${VariableLengthOnion.rfcName}" -> "mandatory",
       s"features.${PaymentSecret.rfcName}" -> "mandatory",
-      s"features.${BasicMultiPartPayment.rfcName}" -> "optional"
+      s"features.${BasicMultiPartPayment.rfcName}" -> "optional",
     ).asJava)
 
     // var_onion_optin cannot be disabled
     val noVariableLengthOnionConf = ConfigFactory.parseMap(Map(
       s"features.${OptionDataLossProtect.rfcName}" -> "optional",
       s"features.${ChannelRangeQueries.rfcName}" -> "optional",
-      s"features.${ChannelRangeQueriesExtended.rfcName}" -> "optional"
+      s"features.${ChannelRangeQueriesExtended.rfcName}" -> "optional",
+      s"features.${ChannelType.rfcName}" -> "optional",
     ).asJava)
 
     // var_onion_optin cannot be optional
     val optionalVarOnionOptinConf = ConfigFactory.parseMap(Map(
       s"features.${OptionDataLossProtect.rfcName}" -> "optional",
-      s"features.${VariableLengthOnion.rfcName}" -> "optional"
+      s"features.${ChannelType.rfcName}" -> "optional",
+      s"features.${VariableLengthOnion.rfcName}" -> "optional",
+      s"features.${PaymentSecret.rfcName}" -> "mandatory",
     ).asJava)
 
     // payment_secret cannot be optional
     val optionalPaymentSecretConf = ConfigFactory.parseMap(Map(
       s"features.${OptionDataLossProtect.rfcName}" -> "optional",
+      s"features.${ChannelType.rfcName}" -> "optional",
       s"features.${VariableLengthOnion.rfcName}" -> "mandatory",
       s"features.${PaymentSecret.rfcName}" -> "optional",
     ).asJava)
 
+    // option_channel_type cannot be disabled
+    val noChannelTypeConf = ConfigFactory.parseMap(Map(
+      s"features.${OptionDataLossProtect.rfcName}" -> "optional",
+      s"features.${ChannelRangeQueries.rfcName}" -> "optional",
+      s"features.${ChannelRangeQueriesExtended.rfcName}" -> "optional",
+      s"features.${VariableLengthOnion.rfcName}" -> "mandatory",
+      s"features.${PaymentSecret.rfcName}" -> "mandatory",
+      s"features.${BasicMultiPartPayment.rfcName}" -> "optional",
+    ).asJava)
+
     // initial_routing_sync cannot be enabled
     val initialRoutingSyncConf = ConfigFactory.parseMap(Map(
       s"features.${OptionDataLossProtect.rfcName}" -> "optional",
       s"features.${InitialRoutingSync.rfcName}" -> "optional",
       s"features.${ChannelRangeQueries.rfcName}" -> "optional",
       s"features.${ChannelRangeQueriesExtended.rfcName}" -> "optional",
+      s"features.${ChannelType.rfcName}" -> "optional",
       s"features.${VariableLengthOnion.rfcName}" -> "mandatory",
       s"features.${PaymentSecret.rfcName}" -> "mandatory",
     ).asJava)
 
     // extended channel queries without channel queries
     val illegalFeaturesConf = ConfigFactory.parseMap(Map(
       s"features.${OptionDataLossProtect.rfcName}" -> "optional",
-      s"features.${ChannelRangeQueriesExtended.rfcName}" -> "optional"
+      s"features.${ChannelRangeQueriesExtended.rfcName}" -> "optional",
+      s"features.${ChannelType.rfcName}" -> "optional",
+      s"features.${VariableLengthOnion.rfcName}" -> "mandatory",
+      s"features.${PaymentSecret.rfcName}" -> "mandatory",
     ).asJava)
 
     assert(Try(makeNodeParamsWithDefaults(finalizeConf(legalFeaturesConf))).isSuccess)
     assert(Try(makeNodeParamsWithDefaults(finalizeConf(noVariableLengthOnionConf))).isFailure)
     assert(Try(makeNodeParamsWithDefaults(finalizeConf(optionalVarOnionOptinConf))).isFailure)
     assert(Try(makeNodeParamsWithDefaults(finalizeConf(optionalPaymentSecretConf))).isFailure)
+    assert(Try(makeNodeParamsWithDefaults(finalizeConf(noChannelTypeConf))).isFailure)
     assert(Try(makeNodeParamsWithDefaults(finalizeConf(initialRoutingSyncConf))).isFailure)
     assert(Try(makeNodeParamsWithDefaults(finalizeConf(illegalFeaturesConf))).isFailure)
   }
@@ -153,6 +173,7 @@ class StartupSpec extends AnyFunSuite {
         |            var_onion_optin = mandatory
         |            payment_secret = mandatory
         |            basic_mpp = mandatory
+        |            option_channel_type = optional
         |          }
         |      }
         |  ]
@@ -161,7 +182,7 @@ class StartupSpec extends AnyFunSuite {
 
     val nodeParams = makeNodeParamsWithDefaults(perNodeConf.withFallback(defaultConf))
     val perNodeFeatures = nodeParams.featuresFor(PublicKey(ByteVector.fromValidHex("02aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")))
-    assert(perNodeFeatures === Features(VariableLengthOnion -> Mandatory, PaymentSecret -> Mandatory, BasicMultiPartPayment -> Mandatory))
+    assert(perNodeFeatures === Features(VariableLengthOnion -> Mandatory, PaymentSecret -> Mandatory, BasicMultiPartPayment -> Mandatory, ChannelType -> Optional))
   }
 
   test("override feerate mismatch tolerance") {

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

@@ -80,6 +80,8 @@ object ChannelStateTestsTags {
   val HighDustLimitDifferenceAliceBob = "high_dust_limit_difference_alice_bob"
   /** If set, Bob will have a much higher dust limit than Alice. */
   val HighDustLimitDifferenceBobAlice = "high_dust_limit_difference_bob_alice"
+  /** If set, channels will use option_channel_type. */
+  val ChannelType = "option_channel_type"
 }
 
 trait ChannelStateTestsHelperMethods extends TestKitBase {
@@ -142,13 +144,15 @@ trait ChannelStateTestsHelperMethods extends TestKitBase {
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.AnchorOutputsZeroFeeHtlcTxs))(_.updated(Features.StaticRemoteKey, FeatureSupport.Optional).updated(Features.AnchorOutputs, FeatureSupport.Optional).updated(Features.AnchorOutputsZeroFeeHtlcTx, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ShutdownAnySegwit))(_.updated(Features.ShutdownAnySegwit, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionUpfrontShutdownScript))(_.updated(Features.OptionUpfrontShutdownScript, FeatureSupport.Optional))
+      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ChannelType))(_.updated(Features.ChannelType, FeatureSupport.Optional))
     val bobInitFeatures = Bob.nodeParams.features
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.Wumbo))(_.updated(Features.Wumbo, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.StaticRemoteKey))(_.updated(Features.StaticRemoteKey, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.AnchorOutputs))(_.updated(Features.StaticRemoteKey, FeatureSupport.Optional).updated(Features.AnchorOutputs, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.AnchorOutputsZeroFeeHtlcTxs))(_.updated(Features.StaticRemoteKey, FeatureSupport.Optional).updated(Features.AnchorOutputs, FeatureSupport.Optional).updated(Features.AnchorOutputsZeroFeeHtlcTx, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ShutdownAnySegwit))(_.updated(Features.ShutdownAnySegwit, FeatureSupport.Optional))
       .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.OptionUpfrontShutdownScript))(_.updated(Features.OptionUpfrontShutdownScript, FeatureSupport.Optional))
+      .modify(_.activated).usingIf(tags.contains(ChannelStateTestsTags.ChannelType))(_.updated(Features.ChannelType, FeatureSupport.Optional))
 
     val channelType = ChannelTypes.defaultFromFeatures(aliceInitFeatures, bobInitFeatures)
 

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

@@ -114,6 +114,16 @@ class WaitForAcceptChannelStateSpec extends TestKitBaseClass with FixtureAnyFunS
     aliceOrigin.expectNoMessage()
   }
 
+  test("recv AcceptChannel (channel type not set but feature bit set)", Tag(ChannelStateTestsTags.ChannelType), Tag(ChannelStateTestsTags.AnchorOutputsZeroFeeHtlcTxs)) { f =>
+    import f._
+    val accept = bob2alice.expectMsgType[AcceptChannel]
+    assert(accept.channelType_opt === Some(ChannelTypes.AnchorOutputsZeroFeeHtlcTx))
+    bob2alice.forward(alice, accept.copy(tlvStream = TlvStream.empty))
+    alice2bob.expectMsg(Error(accept.temporaryChannelId, "option_channel_type was negotiated but channel_type is missing"))
+    awaitCond(alice.stateName == CLOSED)
+    aliceOrigin.expectMsgType[Status.Failure]
+  }
+
   test("recv AcceptChannel (non-default channel type)", Tag(ChannelStateTestsTags.AnchorOutputsZeroFeeHtlcTxs), Tag("standard-channel-type")) { f =>
     import f._
     val accept = bob2alice.expectMsgType[AcceptChannel]