Update trampoline to use official spec values

docs/release-notes/eclair-vnext.md

@@ -4,7 +4,19 @@
 
 ## Major changes
 
-<insert changes>
+### Trampoline payments
+
+Trampoline payments allow nodes running on constrained devices to sync only a small portion of the network and leverage trampoline nodes to calculate the missing parts of the payment route, while providing the same privacy as fully source-routed payments.
+
+Eclair started supporting [trampoline payments](https://github.com/lightning/bolts/pull/829) in v0.3.3.
+The specification has evolved since then and has recently been added to the [BOLTs](https://github.com/lightning/bolts/pull/836).
+
+With this release, eclair nodes are able to relay and receive trampoline payments (activated by default).
+This feature can be disabled if you don't want to relay or receive trampoline payments:
+
+```conf
+eclair.features.trampoline_routing = disabled
+```
 
 ### Configuration changes
 

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

@@ -49,7 +49,6 @@ eclair {
   node-alias = "eclair"
   node-color = "49daaa"
 
-  trampoline-payments-enable = false // TODO: @t-bast: once spec-ed this should use a global feature flag
   // see https://github.com/lightningnetwork/lightning-rfc/blob/master/09-features.md
   features {
     // option_upfront_shutdown_script is not activated by default.
@@ -91,6 +90,7 @@ eclair {
     option_simple_close = optional
     option_splice = optional
     option_simple_taproot = optional
+    trampoline_routing = optional
     trampoline_payment_prototype = disabled
     async_payment_prototype = disabled
     on_the_fly_funding = disabled
@@ -733,11 +733,11 @@ eclair {
 
   offers {
     // Minimum length of an offer blinded path when hiding our real node id
-    message-path-min-length = 2
+    message-path-min-length = 1
     // Number of payment paths to put in Bolt12 invoices when hiding our real node id
-    payment-path-count = 2
+    payment-path-count = 1
     // Length of payment paths to put in Bolt12 invoices when hiding our real node id
-    payment-path-length = 2
+    payment-path-length = 1
     // Expiry delta of payment paths to put in Bolt12 invoices when hiding our real node id
     payment-path-expiry-delta = 500
   }

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

@@ -144,6 +144,8 @@ trait Eclair {
 
   def sendBlocking(externalId_opt: Option[String], amount: MilliSatoshi, invoice: Bolt11Invoice, maxAttempts_opt: Option[Int] = None, maxFeeFlat_opt: Option[Satoshi] = None, maxFeePct_opt: Option[Double] = None, pathFindingExperimentName_opt: Option[String] = None)(implicit timeout: Timeout): Future[PaymentEvent]
 
+  def sendTrampoline(trampolineNodeId: PublicKey, amount: MilliSatoshi, invoice: Bolt11Invoice)(implicit timeout: Timeout): Future[PaymentEvent]
+
   def sendWithPreimage(externalId_opt: Option[String], recipientNodeId: PublicKey, amount: MilliSatoshi, paymentPreimage: ByteVector32 = randomBytes32(), maxAttempts_opt: Option[Int] = None, maxFeeFlat_opt: Option[Satoshi] = None, maxFeePct_opt: Option[Double] = None, pathFindingExperimentName_opt: Option[String] = None)(implicit timeout: Timeout): Future[UUID]
 
   def sentInfo(id: PaymentIdentifier)(implicit timeout: Timeout): Future[Seq[OutgoingPayment]]
@@ -544,6 +546,11 @@ class EclairImpl(val appKit: Kit) extends Eclair with Logging with SpendFromChan
     }
   }
 
+  override def sendTrampoline(trampolineNodeId: PublicKey, amount: MilliSatoshi, invoice: Bolt11Invoice)(implicit timeout: Timeout): Future[PaymentEvent] = {
+    val routeParams = appKit.nodeParams.routerConf.pathFindingExperimentConf.getRandomConf().getDefaultRouteParams
+    appKit.paymentInitiator.toTyped.ask[PaymentEvent](ref => SendTrampolinePayment(ref.toClassic, invoice, trampolineNodeId, routeParams, blockUntilComplete = true))
+  }
+
   override def sendWithPreimage(externalId_opt: Option[String], recipientNodeId: PublicKey, amount: MilliSatoshi, paymentPreimage: ByteVector32, maxAttempts_opt: Option[Int], maxFeeFlat_opt: Option[Satoshi], maxFeePct_opt: Option[Double], pathFindingExperimentName_opt: Option[String])(implicit timeout: Timeout): Future[UUID] = {
     val maxAttempts = maxAttempts_opt.getOrElse(appKit.nodeParams.maxPaymentAttempts)
     getRouteParams(pathFindingExperimentName_opt) match {

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

@@ -394,6 +394,11 @@ object Features {
     val mandatory = 54
   }
 
+  case object TrampolinePayment extends Feature with InitFeature with NodeFeature with Bolt11Feature with Bolt12Feature {
+    val rfcName = "trampoline_routing"
+    val mandatory = 56
+  }
+
   case object SimpleClose extends Feature with InitFeature with NodeFeature {
     val rfcName = "option_simple_close"
     val mandatory = 60
@@ -420,12 +425,7 @@ object Features {
     val mandatory = 132
   }
 
-  // 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`.
-  // The version of trampoline enabled by this feature bit does not match the latest spec PR: once the spec is accepted,
-  // we will introduce a new version of trampoline that will work in parallel to this legacy one, until we can safely
-  // deprecate it.
+  // TODO: we can remove this feature once we've migrated existing Phoenix users
   case object TrampolinePaymentPrototype extends Feature with InitFeature with NodeFeature with Bolt11Feature {
     val rfcName = "trampoline_payment_prototype"
     val mandatory = 148
@@ -496,6 +496,7 @@ object Features {
     SimpleTaprootChannels,
     SimpleTaprootChannelsPhoenix,
     WakeUpNotificationClient,
+    TrampolinePayment,
     TrampolinePaymentPrototype,
     AsyncPaymentPrototype,
     SplicePrototype,
@@ -512,12 +513,11 @@ object Features {
     AnchorOutputs -> (StaticRemoteKey :: Nil),
     AnchorOutputsZeroFeeHtlcTx -> (StaticRemoteKey :: Nil),
     RouteBlinding -> (VariableLengthOnion :: Nil),
-    TrampolinePaymentPrototype -> (PaymentSecret :: Nil),
     KeySend -> (VariableLengthOnion :: Nil),
     SimpleClose -> (ShutdownAnySegwit :: Nil),
     SimpleTaprootChannels -> (ChannelType :: SimpleClose :: Nil),
     SimpleTaprootChannelsPhoenix -> (ChannelType :: SimpleClose :: Nil),
-    AsyncPaymentPrototype -> (TrampolinePaymentPrototype :: Nil),
+    AsyncPaymentPrototype -> (TrampolinePayment :: Nil),
     FundingFeeCredit -> (OnTheFlyFunding :: Nil)
   )
 

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

@@ -85,7 +85,6 @@ case class NodeParams(nodeKeyManager: NodeKeyManager,
                       socksProxy_opt: Option[Socks5ProxyParams],
                       maxPaymentAttempts: Int,
                       paymentFinalExpiry: PaymentFinalExpiryConf,
-                      enableTrampolinePayment: Boolean,
                       balanceCheckInterval: FiniteDuration,
                       blockchainWatchdogThreshold: Int,
                       blockchainWatchdogSources: Seq[String],
@@ -691,7 +690,6 @@ object NodeParams extends Logging {
       socksProxy_opt = socksProxy_opt,
       maxPaymentAttempts = config.getInt("max-payment-attempts"),
       paymentFinalExpiry = PaymentFinalExpiryConf(CltvExpiryDelta(config.getInt("send.recipient-final-expiry.min-delta")), CltvExpiryDelta(config.getInt("send.recipient-final-expiry.max-delta"))),
-      enableTrampolinePayment = config.getBoolean("trampoline-payments-enable"),
       balanceCheckInterval = FiniteDuration(config.getDuration("balance-check-interval").getSeconds, TimeUnit.SECONDS),
       blockchainWatchdogThreshold = config.getInt("blockchain-watchdog.missing-blocks-threshold"),
       blockchainWatchdogSources = config.getStringList("blockchain-watchdog.sources").asScala.toSeq,

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

@@ -242,7 +242,7 @@ case class FailureAttributionData(htlcReceivedAt: TimestampMilli, trampolineRece
 case class FulfillAttributionData(htlcReceivedAt: TimestampMilli, trampolineReceivedAt_opt: Option[TimestampMilli], downstreamAttribution_opt: Option[ByteVector])
 
 sealed trait HtlcSettlementCommand extends HasOptionalReplyToCommand with ForbiddenCommandDuringQuiescenceNegotiation with ForbiddenCommandWhenQuiescent { def id: Long }
-final case class CMD_FULFILL_HTLC(id: Long, r: ByteVector32, attribution_opt: Option[FulfillAttributionData], commit: Boolean = false, replyTo_opt: Option[ActorRef] = None) extends HtlcSettlementCommand
+final case class CMD_FULFILL_HTLC(id: Long, r: ByteVector32, fulfillmentPayload_opt: Option[ByteVector], attribution_opt: Option[FulfillAttributionData], commit: Boolean = false, replyTo_opt: Option[ActorRef] = None) extends HtlcSettlementCommand
 final case class CMD_FAIL_HTLC(id: Long, reason: FailureReason, attribution_opt: Option[FailureAttributionData], delay_opt: Option[FiniteDuration] = None, commit: Boolean = false, replyTo_opt: Option[ActorRef] = None) extends HtlcSettlementCommand
 final case class CMD_FAIL_MALFORMED_HTLC(id: Long, onionHash: ByteVector32, failureCode: Int, commit: Boolean = false, replyTo_opt: Option[ActorRef] = None) extends HtlcSettlementCommand
 final case class CMD_UPDATE_FEE(feeratePerKw: FeeratePerKw, commit: Boolean = false, replyTo_opt: Option[ActorRef] = None) extends HasOptionalReplyToCommand with ForbiddenCommandDuringQuiescenceNegotiation with ForbiddenCommandWhenQuiescent
@@ -304,7 +304,13 @@ final case class RES_FAILURE[+C <: Command, +T <: Throwable](cmd: C, t: T) exten
 final case class RES_ADD_FAILED[+T <: ChannelException](c: CMD_ADD_HTLC, t: T, channelUpdate: Option[ChannelUpdate]) extends CommandFailure[CMD_ADD_HTLC, T] { override def toString = s"cannot add htlc with origin=${c.origin} reason=${t.getMessage}" }
 sealed trait HtlcResult
 object HtlcResult {
-  sealed trait Fulfill extends HtlcResult { def paymentPreimage: ByteVector32 }
+  sealed trait Fulfill extends HtlcResult {
+    def paymentPreimage: ByteVector32
+    def fulfillmentPayload_opt: Option[ByteVector] = this match {
+      case RemoteFulfill(fulfill) => fulfill.fulfillmentPayload_opt
+      case _: OnChainFulfill => None
+    }
+  }
   case class RemoteFulfill(fulfill: UpdateFulfillHtlc) extends Fulfill { override val paymentPreimage: ByteVector32 = fulfill.paymentPreimage }
   case class OnChainFulfill(paymentPreimage: ByteVector32) extends Fulfill
   sealed trait Fail extends HtlcResult