Relay onion messages to compact node id (#2821)

To save space, blinded routes may use a compact node id (scid + direction instead of public key) as an introduction node. When using such a compact route, the sender must use it's knowledge of the network to convert that to a public key, however trampoline users don't have that knowledge, they must transmit the compact route to the trempoline provider. We extend the spec to allow compact node ids in the `next_node_id` field. Co-authored-by: t-bast <[email protected]>
ACINQ · Feb 19, 2024 · 86c4837 · 86c4837
1 parent 62b739a
commit 86c4837
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diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/EncodedNodeId.scala b/eclair-core/src/main/scala/fr/acinq/eclair/EncodedNodeId.scala
@@ -0,0 +1,19 @@
+package fr.acinq.eclair
+
+import fr.acinq.bitcoin.scalacompat.Crypto.PublicKey
+
+sealed trait EncodedNodeId
+
+object EncodedNodeId {
+  /** Nodes are usually identified by their public key. */
+  case class Plain(publicKey: PublicKey) extends EncodedNodeId {
+    override def toString: String = publicKey.toString
+  }
+
+  /** For compactness, nodes may be identified by the shortChannelId of one of their public channels. */
+  case class ShortChannelIdDir(isNode1: Boolean, scid: RealShortChannelId) extends EncodedNodeId {
+    override def toString: String = if (isNode1) s"<-$scid" else s"$scid->"
+  }
+
+  def apply(publicKey: PublicKey): EncodedNodeId = Plain(publicKey)
+}
diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/Setup.scala b/eclair-core/src/main/scala/fr/acinq/eclair/Setup.scala
@@ -366,7 +366,7 @@ class Setup(val datadir: File,
       txPublisherFactory = Channel.SimpleTxPublisherFactory(nodeParams, watcher, bitcoinClient)
       channelFactory = Peer.SimpleChannelFactory(nodeParams, watcher, relayer, bitcoinClient, txPublisherFactory)
       pendingChannelsRateLimiter = system.spawn(Behaviors.supervise(PendingChannelsRateLimiter(nodeParams, router.toTyped, channels)).onFailure(typed.SupervisorStrategy.resume), name = "pending-channels-rate-limiter")
-      peerFactory = Switchboard.SimplePeerFactory(nodeParams, bitcoinClient, channelFactory, pendingChannelsRateLimiter, register)
+      peerFactory = Switchboard.SimplePeerFactory(nodeParams, bitcoinClient, channelFactory, pendingChannelsRateLimiter, register, router.toTyped)
 
       switchboard = system.actorOf(SimpleSupervisor.props(Switchboard.props(nodeParams, peerFactory), "switchboard", SupervisorStrategy.Resume))
       _ = switchboard ! Switchboard.Init(channels)

diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/io/MessageRelay.scala b/eclair-core/src/main/scala/fr/acinq/eclair/io/MessageRelay.scala
@@ -17,25 +17,27 @@
 package fr.acinq.eclair.io
 
 import akka.actor.typed.Behavior
+import akka.actor.typed.eventstream.EventStream
 import akka.actor.typed.scaladsl.adapter.TypedActorRefOps
 import akka.actor.typed.scaladsl.{ActorContext, Behaviors}
 import akka.actor.{ActorRef, typed}
 import fr.acinq.bitcoin.scalacompat.ByteVector32
 import fr.acinq.bitcoin.scalacompat.Crypto.PublicKey
-import fr.acinq.eclair.ShortChannelId
 import fr.acinq.eclair.channel.Register
 import fr.acinq.eclair.io.Peer.{PeerInfo, PeerInfoResponse}
 import fr.acinq.eclair.io.Switchboard.GetPeerInfo
+import fr.acinq.eclair.message.OnionMessages
+import fr.acinq.eclair.message.OnionMessages.DropReason
+import fr.acinq.eclair.router.Router
 import fr.acinq.eclair.wire.protocol.OnionMessage
+import fr.acinq.eclair.{EncodedNodeId, NodeParams, ShortChannelId}
 
 object MessageRelay {
   // @formatter:off
   sealed trait Command
   case class RelayMessage(messageId: ByteVector32,
-                          switchboard: ActorRef,
-                          register: ActorRef,
                           prevNodeId: PublicKey,
-                          nextNode: Either[ShortChannelId, PublicKey],
+                          nextNode: Either[ShortChannelId, EncodedNodeId],
                           msg: OnionMessage,
                           policy: RelayPolicy,
                           replyTo_opt: Option[typed.ActorRef[Status]]) extends Command
@@ -60,66 +62,101 @@ object MessageRelay {
   case class UnknownOutgoingChannel(messageId: ByteVector32, outgoingChannelId: ShortChannelId) extends Failure {
     override def toString: String = s"Unknown outgoing channel: $outgoingChannelId"
   }
+  case class DroppedMessage(messageId: ByteVector32, reason: DropReason) extends Failure {
+    override def toString: String = s"Message dropped: $reason"
+  }
 
   sealed trait RelayPolicy
   case object RelayChannelsOnly extends RelayPolicy
   case object RelayAll extends RelayPolicy
   // @formatter:on
 
-  def apply(): Behavior[Command] = {
-    Behaviors.receivePartial {
-      case (context, RelayMessage(messageId, switchboard, register, prevNodeId, Left(outgoingChannelId), msg, policy, replyTo_opt)) =>
+  def apply(nodeParams: NodeParams,
+            switchboard: ActorRef,
+            register: ActorRef,
+            router: typed.ActorRef[Router.GetNodeId]): Behavior[Command] = {
+    Behaviors.setup { context =>
+      Behaviors.receiveMessagePartial {
+        case RelayMessage(messageId, prevNodeId, nextNode, msg, policy, replyTo_opt) =>
+          val relay = new MessageRelay(nodeParams, messageId, prevNodeId, policy, switchboard, register, router, replyTo_opt, context)
+          relay.queryNextNodeId(msg, nextNode)
+      }
+    }
+  }
+}
+
+private class MessageRelay(nodeParams: NodeParams,
+                           messageId: ByteVector32,
+                           prevNodeId: PublicKey,
+                           policy: MessageRelay.RelayPolicy,
+                           switchboard: ActorRef,
+                           register: ActorRef,
+                           router: typed.ActorRef[Router.GetNodeId],
+                           replyTo_opt: Option[typed.ActorRef[MessageRelay.Status]],
+                           context: ActorContext[MessageRelay.Command]) {
+
+  import MessageRelay._
+
+  def queryNextNodeId(msg: OnionMessage, nextNode: Either[ShortChannelId, EncodedNodeId]): Behavior[Command] = {
+    nextNode match {
+      case Left(outgoingChannelId) =>
         register ! Register.GetNextNodeId(context.messageAdapter(WrappedOptionalNodeId), outgoingChannelId)
-        waitForNextNodeId(messageId, switchboard, prevNodeId, outgoingChannelId, msg, policy, replyTo_opt)
-      case (context, RelayMessage(messageId, switchboard, _, prevNodeId, Right(nextNodeId), msg, policy, replyTo_opt)) =>
-        withNextNodeId(context, messageId, switchboard, prevNodeId, nextNodeId, msg, policy, replyTo_opt)
+        waitForNextNodeId(msg, outgoingChannelId)
+      case Right(EncodedNodeId.ShortChannelIdDir(isNode1, scid)) =>
+        router ! Router.GetNodeId(context.messageAdapter(WrappedOptionalNodeId), scid, isNode1)
+        waitForNextNodeId(msg, scid)
+      case Right(EncodedNodeId.Plain(nextNodeId)) =>
+        withNextNodeId(msg, nextNodeId)
     }
   }
 
-  def waitForNextNodeId(messageId: ByteVector32,
-                        switchboard: ActorRef,
-                        prevNodeId: PublicKey,
-                        outgoingChannelId: ShortChannelId,
-                        msg: OnionMessage,
-                        policy: RelayPolicy,
-                        replyTo_opt: Option[typed.ActorRef[Status]]): Behavior[Command] =
-    Behaviors.receivePartial {
-      case (_, WrappedOptionalNodeId(None)) =>
+  private def waitForNextNodeId(msg: OnionMessage, outgoingChannelId: ShortChannelId): Behavior[Command] =
+    Behaviors.receiveMessagePartial {
+      case WrappedOptionalNodeId(None) =>
         replyTo_opt.foreach(_ ! UnknownOutgoingChannel(messageId, outgoingChannelId))
         Behaviors.stopped
-      case (context, WrappedOptionalNodeId(Some(nextNodeId))) =>
-        withNextNodeId(context, messageId, switchboard, prevNodeId, nextNodeId, msg, policy, replyTo_opt)
+      case WrappedOptionalNodeId(Some(nextNodeId)) =>
+        withNextNodeId(msg, nextNodeId)
     }
 
-  def withNextNodeId(context: ActorContext[Command],
-                     messageId: ByteVector32,
-                     switchboard: ActorRef,
-                     prevNodeId: PublicKey,
-                     nextNodeId: PublicKey,
-                     msg: OnionMessage,
-                     policy: RelayPolicy,
-                     replyTo_opt: Option[typed.ActorRef[Status]]): Behavior[Command] =
-        policy match {
-          case RelayChannelsOnly =>
-            switchboard ! GetPeerInfo(context.messageAdapter(WrappedPeerInfo), prevNodeId)
-            waitForPreviousPeer(messageId, switchboard, nextNodeId, msg, replyTo_opt)
-          case RelayAll =>
-            switchboard ! Peer.Connect(nextNodeId, None, context.messageAdapter(WrappedConnectionResult).toClassic, isPersistent = false)
-            waitForConnection(messageId, msg, replyTo_opt)
-        }
+  private def withNextNodeId(msg: OnionMessage, nextNodeId: PublicKey): Behavior[Command] = {
+    if (nextNodeId == nodeParams.nodeId) {
+      OnionMessages.process(nodeParams.privateKey, msg) match {
+        case OnionMessages.DropMessage(reason) =>
+          replyTo_opt.foreach(_ ! DroppedMessage(messageId, reason))
+          Behaviors.stopped
+        case OnionMessages.SendMessage(nextNode, nextMessage) =>
+          // We need to repeat the process until we identify the (real) next node, or find out that we're the recipient.
+          queryNextNodeId(nextMessage, nextNode)
+        case received: OnionMessages.ReceiveMessage =>
+          context.system.eventStream ! EventStream.Publish(received)
+          replyTo_opt.foreach(_ ! Sent(messageId))
+          Behaviors.stopped
+      }
+    } else {
+      policy match {
+        case RelayChannelsOnly =>
+          switchboard ! GetPeerInfo(context.messageAdapter(WrappedPeerInfo), prevNodeId)
+          waitForPreviousPeerForPolicyCheck(msg, nextNodeId)
+        case RelayAll =>
+          switchboard ! Peer.Connect(nextNodeId, None, context.messageAdapter(WrappedConnectionResult).toClassic, isPersistent = false)
+          waitForConnection(msg)
+      }
+    }
+  }
 
-  def waitForPreviousPeer(messageId: ByteVector32, switchboard: ActorRef, nextNodeId: PublicKey, msg: OnionMessage, replyTo_opt: Option[typed.ActorRef[Status]]): Behavior[Command] = {
-    Behaviors.receivePartial {
-      case (context, WrappedPeerInfo(PeerInfo(_, _, _, _, channels))) if channels.nonEmpty =>
+  private def waitForPreviousPeerForPolicyCheck(msg: OnionMessage, nextNodeId: PublicKey): Behavior[Command] = {
+    Behaviors.receiveMessagePartial {
+      case WrappedPeerInfo(PeerInfo(_, _, _, _, channels)) if channels.nonEmpty =>
         switchboard ! GetPeerInfo(context.messageAdapter(WrappedPeerInfo), nextNodeId)
-        waitForNextPeer(messageId, msg, replyTo_opt)
+        waitForNextPeerForPolicyCheck(msg)
       case _ =>
         replyTo_opt.foreach(_ ! AgainstPolicy(messageId, RelayChannelsOnly))
         Behaviors.stopped
     }
   }
 
-  def waitForNextPeer(messageId: ByteVector32, msg: OnionMessage, replyTo_opt: Option[typed.ActorRef[Status]]): Behavior[Command] = {
+  private def waitForNextPeerForPolicyCheck(msg: OnionMessage): Behavior[Command] = {
     Behaviors.receiveMessagePartial {
       case WrappedPeerInfo(PeerInfo(peer, _, _, _, channels)) if channels.nonEmpty =>
         peer ! Peer.RelayOnionMessage(messageId, msg, replyTo_opt)
@@ -130,7 +167,7 @@ object MessageRelay {
     }
   }
 
-  def waitForConnection(messageId: ByteVector32, msg: OnionMessage, replyTo_opt: Option[typed.ActorRef[Status]]): Behavior[Command] = {
+  private def waitForConnection(msg: OnionMessage): Behavior[Command] = {
     Behaviors.receiveMessagePartial {
       case WrappedConnectionResult(r: PeerConnection.ConnectionResult.HasConnection) =>
         r.peer ! Peer.RelayOnionMessage(messageId, msg, replyTo_opt)

diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/io/Peer.scala b/eclair-core/src/main/scala/fr/acinq/eclair/io/Peer.scala
@@ -38,6 +38,7 @@ import fr.acinq.eclair.io.OpenChannelInterceptor.{OpenChannelInitiator, OpenChan
 import fr.acinq.eclair.io.PeerConnection.KillReason
 import fr.acinq.eclair.message.OnionMessages
 import fr.acinq.eclair.remote.EclairInternalsSerializer.RemoteTypes
+import fr.acinq.eclair.router.Router
 import fr.acinq.eclair.wire.protocol
 import fr.acinq.eclair.wire.protocol.{Error, HasChannelId, HasTemporaryChannelId, LightningMessage, NodeAddress, OnionMessage, RoutingMessage, UnknownMessage, Warning}
 
@@ -51,7 +52,14 @@ import fr.acinq.eclair.wire.protocol.{Error, HasChannelId, HasTemporaryChannelId
  *
  * Created by PM on 26/08/2016.
  */
-class Peer(val nodeParams: NodeParams, remoteNodeId: PublicKey, wallet: OnchainPubkeyCache, channelFactory: Peer.ChannelFactory, switchboard: ActorRef, register: ActorRef, pendingChannelsRateLimiter: typed.ActorRef[PendingChannelsRateLimiter.Command]) extends FSMDiagnosticActorLogging[Peer.State, Peer.Data] {
+class Peer(val nodeParams: NodeParams,
+           remoteNodeId: PublicKey,
+           wallet: OnchainPubkeyCache,
+           channelFactory: Peer.ChannelFactory,
+           switchboard: ActorRef,
+           register: ActorRef,
+           router: typed.ActorRef[Router.GetNodeId],
+           pendingChannelsRateLimiter: typed.ActorRef[PendingChannelsRateLimiter.Command]) extends FSMDiagnosticActorLogging[Peer.State, Peer.Data] {
 
   import Peer._
 
@@ -279,8 +287,8 @@ class Peer(val nodeParams: NodeParams, remoteNodeId: PublicKey, wallet: OnchainP
             log.debug("dropping message from {}: {}", remoteNodeId.value.toHex, reason.toString)
           case OnionMessages.SendMessage(nextNode, message) if nodeParams.features.hasFeature(Features.OnionMessages) =>
             val messageId = randomBytes32()
-            val relay = context.spawn(Behaviors.supervise(MessageRelay()).onFailure(typed.SupervisorStrategy.stop), s"relay-message-$messageId")
-            relay ! MessageRelay.RelayMessage(messageId, switchboard, register, remoteNodeId, nextNode, message, nodeParams.onionMessageConfig.relayPolicy, None)
+            val relay = context.spawn(Behaviors.supervise(MessageRelay(nodeParams, switchboard, register, router)).onFailure(typed.SupervisorStrategy.stop), s"relay-message-$messageId")
+            relay ! MessageRelay.RelayMessage(messageId, remoteNodeId, nextNode, message, nodeParams.onionMessageConfig.relayPolicy, None)
           case OnionMessages.SendMessage(_, _) =>
             log.debug("dropping message from {}: relaying onion messages is disabled", remoteNodeId.value.toHex)
           case received: OnionMessages.ReceiveMessage =>
@@ -458,7 +466,8 @@ object Peer {
       context.actorOf(Channel.props(nodeParams, wallet, remoteNodeId, watcher, relayer, txPublisherFactory))
   }
 
-  def props(nodeParams: NodeParams, remoteNodeId: PublicKey, wallet: OnchainPubkeyCache, channelFactory: ChannelFactory, switchboard: ActorRef, register: ActorRef, pendingChannelsRateLimiter: typed.ActorRef[PendingChannelsRateLimiter.Command]): Props = Props(new Peer(nodeParams, remoteNodeId, wallet, channelFactory, switchboard, register, pendingChannelsRateLimiter))
+  def props(nodeParams: NodeParams, remoteNodeId: PublicKey, wallet: OnchainPubkeyCache, channelFactory: ChannelFactory, switchboard: ActorRef, register: ActorRef, router: typed.ActorRef[Router.GetNodeId], pendingChannelsRateLimiter: typed.ActorRef[PendingChannelsRateLimiter.Command]): Props =
+    Props(new Peer(nodeParams, remoteNodeId, wallet, channelFactory, switchboard, register, router, pendingChannelsRateLimiter))
 
   // @formatter:off
 

diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/io/Switchboard.scala b/eclair-core/src/main/scala/fr/acinq/eclair/io/Switchboard.scala
@@ -27,6 +27,7 @@ import fr.acinq.eclair.channel._
 import fr.acinq.eclair.io.IncomingConnectionsTracker.TrackIncomingConnection
 import fr.acinq.eclair.io.Peer.{PeerInfoResponse, PeerNotFound}
 import fr.acinq.eclair.remote.EclairInternalsSerializer.RemoteTypes
+import fr.acinq.eclair.router.Router
 import fr.acinq.eclair.router.Router.RouterConf
 import fr.acinq.eclair.{NodeParams, SubscriptionsComplete}
 
@@ -159,9 +160,9 @@ object Switchboard {
     def spawn(context: ActorContext, remoteNodeId: PublicKey): ActorRef
   }
 
-  case class SimplePeerFactory(nodeParams: NodeParams, wallet: OnchainPubkeyCache, channelFactory: Peer.ChannelFactory, pendingChannelsRateLimiter: typed.ActorRef[PendingChannelsRateLimiter.Command], register: ActorRef) extends PeerFactory {
+  case class SimplePeerFactory(nodeParams: NodeParams, wallet: OnchainPubkeyCache, channelFactory: Peer.ChannelFactory, pendingChannelsRateLimiter: typed.ActorRef[PendingChannelsRateLimiter.Command], register: ActorRef, router: typed.ActorRef[Router.GetNodeId]) extends PeerFactory {
     override def spawn(context: ActorContext, remoteNodeId: PublicKey): ActorRef =
-      context.actorOf(Peer.props(nodeParams, remoteNodeId, wallet, channelFactory, context.self, register, pendingChannelsRateLimiter), name = peerActorName(remoteNodeId))
+      context.actorOf(Peer.props(nodeParams, remoteNodeId, wallet, channelFactory, context.self, register, router, pendingChannelsRateLimiter), name = peerActorName(remoteNodeId))
   }
 
   def props(nodeParams: NodeParams, peerFactory: PeerFactory) = Props(new Switchboard(nodeParams, peerFactory))

diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/message/OnionMessages.scala b/eclair-core/src/main/scala/fr/acinq/eclair/message/OnionMessages.scala
@@ -17,7 +17,7 @@
 package fr.acinq.eclair.message
 
 import fr.acinq.bitcoin.scalacompat.Crypto.{PrivateKey, PublicKey}
-import fr.acinq.eclair.ShortChannelId
+import fr.acinq.eclair.{EncodedNodeId, ShortChannelId}
 import fr.acinq.eclair.crypto.Sphinx
 import fr.acinq.eclair.io.MessageRelay.RelayPolicy
 import fr.acinq.eclair.wire.protocol.MessageOnion.{FinalPayload, IntermediatePayload}
@@ -105,9 +105,9 @@ object OnionMessages {
           case Left(_) => None
           case Right(decoded) =>
             decoded.tlvs.get[RouteBlindingEncryptedDataTlv.OutgoingNodeId] match {
-              case None => None
-              case Some(RouteBlindingEncryptedDataTlv.OutgoingNodeId(nextNodeId)) =>
+              case Some(RouteBlindingEncryptedDataTlv.OutgoingNodeId(EncodedNodeId.Plain(nextNodeId))) =>
                 Some(Sphinx.RouteBlinding.BlindedRoute(nextNodeId, decoded.nextBlinding, route.blindedNodes.tail))
+              case _ => None // TODO: allow compact node id and OutgoingChannelId
             }
         }
       case BlindedPath(route) if intermediateNodes.isEmpty => Some(route)
@@ -165,7 +165,7 @@ object OnionMessages {
   // @formatter:off
   sealed trait Action
   case class DropMessage(reason: DropReason) extends Action
-  case class SendMessage(nextNode: Either[ShortChannelId, PublicKey], message: OnionMessage) extends Action
+  case class SendMessage(nextNode: Either[ShortChannelId, EncodedNodeId], message: OnionMessage) extends Action
   case class ReceiveMessage(finalPayload: FinalPayload) extends Action
 
   sealed trait DropReason
@@ -211,8 +211,8 @@ object OnionMessages {
               case Left(f) => DropMessage(f)
               case Right(DecodedEncryptedData(blindedPayload, nextBlinding)) => nextPacket_opt match {
                 case Some(nextPacket) => validateRelayPayload(payload, blindedPayload, nextBlinding, nextPacket) match {
-                  case SendMessage(Right(nextNodeId), nextMsg) if nextNodeId == privateKey.publicKey => process(privateKey, nextMsg)
-                  case SendMessage(Left(outgoingChannelId), nextMsg) if outgoingChannelId == ShortChannelId.toSelf => process(privateKey, nextMsg)
+                  case SendMessage(Right(EncodedNodeId.Plain(publicKey)), nextMsg) if publicKey == privateKey.publicKey => process(privateKey, nextMsg) // TODO: remove and rely on MessageRelay
+                  case SendMessage(Left(outgoingChannelId), nextMsg) if outgoingChannelId == ShortChannelId.toSelf => process(privateKey, nextMsg) // TODO: remove and rely on MessageRelay
                   case action => action
                 }
                 case None => validateFinalPayload(payload, blindedPayload)

diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/message/Postman.scala b/eclair-core/src/main/scala/fr/acinq/eclair/message/Postman.scala
@@ -31,7 +31,7 @@ import fr.acinq.eclair.router.Router.{MessageRoute, MessageRouteNotFound, Messag
 import fr.acinq.eclair.wire.protocol.MessageOnion.{FinalPayload, InvoiceRequestPayload}
 import fr.acinq.eclair.wire.protocol.OfferTypes.{CompactBlindedPath, ContactInfo}
 import fr.acinq.eclair.wire.protocol.{OfferTypes, OnionMessagePayloadTlv, TlvStream}
-import fr.acinq.eclair.{NodeParams, randomBytes32, randomKey}
+import fr.acinq.eclair.{EncodedNodeId, NodeParams, randomBytes32, randomKey}
 
 import scala.collection.mutable
 
@@ -214,8 +214,8 @@ private class SendingMessage(nodeParams: NodeParams,
         replyTo ! Postman.MessageFailed(failure.toString)
         Behaviors.stopped
       case Right((nextNodeId, message)) =>
-        val relay = context.spawn(Behaviors.supervise(MessageRelay()).onFailure(typed.SupervisorStrategy.stop), s"relay-message-$messageId")
-        relay ! MessageRelay.RelayMessage(messageId, switchboard, register, nodeParams.nodeId, Right(nextNodeId), message, MessageRelay.RelayAll, Some(context.messageAdapter[MessageRelay.Status](SendingStatus)))
+        val relay = context.spawn(Behaviors.supervise(MessageRelay(nodeParams, switchboard, register, router)).onFailure(typed.SupervisorStrategy.stop), s"relay-message-$messageId")
+        relay ! MessageRelay.RelayMessage(messageId, nodeParams.nodeId, Right(EncodedNodeId(nextNodeId)), message, MessageRelay.RelayAll, Some(context.messageAdapter[MessageRelay.Status](SendingStatus)))
         waitForSent()
     }
   }