Add private flag to channel updates

Add a message flag to channel update to specify that an update is private
and should not be rebroadcast to other nodes.

We log an error if a private channel update gets into the rebroadcast list.

See lightning/bolts#999

Author: t-bast

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

@@ -634,7 +634,7 @@ class Channel(val nodeParams: NodeParams, val wallet: OnChainChannelFunder, val
       val channelUpdate1 = if (d.channelUpdate.shortChannelId != scidForChannelUpdate) {
         log.info(s"using new scid in channel_update: old=${d.channelUpdate.shortChannelId} new=$scidForChannelUpdate")
         // we re-announce the channelUpdate for the same reason
-        Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate, d.channelUpdate.cltvExpiryDelta, d.channelUpdate.htlcMinimumMsat, d.channelUpdate.feeBaseMsat, d.channelUpdate.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, enable = Helpers.aboveReserve(d.commitments))
+        Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate, d.channelUpdate.cltvExpiryDelta, d.channelUpdate.htlcMinimumMsat, d.channelUpdate.feeBaseMsat, d.channelUpdate.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, isPrivate = !d.commitments.announceChannel, enable = Helpers.aboveReserve(d.commitments))
       } else {
         d.channelUpdate
       }
@@ -667,7 +667,7 @@ class Channel(val nodeParams: NodeParams, val wallet: OnChainChannelFunder, val
               } else {
                 // we generate a new channel_update because the scid used may change if we were previously using an alias
                 val scidForChannelUpdate = Helpers.scidForChannelUpdate(Some(channelAnn), d.shortIds.localAlias)
-                val channelUpdate = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate, d.channelUpdate.cltvExpiryDelta, d.channelUpdate.htlcMinimumMsat, d.channelUpdate.feeBaseMsat, d.channelUpdate.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, enable = Helpers.aboveReserve(d.commitments))
+                val channelUpdate = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate, d.channelUpdate.cltvExpiryDelta, d.channelUpdate.htlcMinimumMsat, d.channelUpdate.feeBaseMsat, d.channelUpdate.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, isPrivate = false, enable = Helpers.aboveReserve(d.commitments))
                 // we use goto() instead of stay() because we want to fire transitions
                 goto(NORMAL) using d.copy(channelAnnouncement = Some(channelAnn), channelUpdate = channelUpdate) storing()
               }
@@ -689,7 +689,7 @@ class Channel(val nodeParams: NodeParams, val wallet: OnChainChannelFunder, val
       }
 
     case Event(c: CMD_UPDATE_RELAY_FEE, d: DATA_NORMAL) =>
-      val channelUpdate1 = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate(d), c.cltvExpiryDelta_opt.getOrElse(d.channelUpdate.cltvExpiryDelta), d.channelUpdate.htlcMinimumMsat, c.feeBase, c.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, enable = Helpers.aboveReserve(d.commitments))
+      val channelUpdate1 = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate(d), c.cltvExpiryDelta_opt.getOrElse(d.channelUpdate.cltvExpiryDelta), d.channelUpdate.htlcMinimumMsat, c.feeBase, c.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, isPrivate = !d.commitments.announceChannel, enable = Helpers.aboveReserve(d.commitments))
       log.info(s"updating relay fees: prev={} next={}", d.channelUpdate.toStringShort, channelUpdate1.toStringShort)
       val replyTo = if (c.replyTo == ActorRef.noSender) sender() else c.replyTo
       replyTo ! RES_SUCCESS(c, d.channelId)
@@ -698,7 +698,7 @@ class Channel(val nodeParams: NodeParams, val wallet: OnChainChannelFunder, val
 
     case Event(BroadcastChannelUpdate(reason), d: DATA_NORMAL) =>
       val age = TimestampSecond.now() - d.channelUpdate.timestamp
-      val channelUpdate1 = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate(d), d.channelUpdate.cltvExpiryDelta, d.channelUpdate.htlcMinimumMsat, d.channelUpdate.feeBaseMsat, d.channelUpdate.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, enable = Helpers.aboveReserve(d.commitments))
+      val channelUpdate1 = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate(d), d.channelUpdate.cltvExpiryDelta, d.channelUpdate.htlcMinimumMsat, d.channelUpdate.feeBaseMsat, d.channelUpdate.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, isPrivate = !d.commitments.announceChannel, enable = Helpers.aboveReserve(d.commitments))
       reason match {
         case Reconnected if d.commitments.announceChannel && Announcements.areSame(channelUpdate1, d.channelUpdate) && age < REFRESH_CHANNEL_UPDATE_INTERVAL =>
           // we already sent an identical channel_update not long ago (flapping protection in case we keep being disconnected/reconnected)
@@ -722,7 +722,7 @@ class Channel(val nodeParams: NodeParams, val wallet: OnChainChannelFunder, val
       // if we have pending unsigned htlcs, then we cancel them and generate an update with the disabled flag set, that will be returned to the sender in a temporary channel failure
       if (d.commitments.localChanges.proposed.collectFirst { case add: UpdateAddHtlc => add }.isDefined) {
         log.debug("updating channel_update announcement (reason=disabled)")
-        val channelUpdate1 = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate(d), d.channelUpdate.cltvExpiryDelta, d.channelUpdate.htlcMinimumMsat, d.channelUpdate.feeBaseMsat, d.channelUpdate.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, enable = false)
+        val channelUpdate1 = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate(d), d.channelUpdate.cltvExpiryDelta, d.channelUpdate.htlcMinimumMsat, d.channelUpdate.feeBaseMsat, d.channelUpdate.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, isPrivate = !d.commitments.announceChannel, enable = false)
         // NB: the htlcs stay() in the commitments.localChange, they will be cleaned up after reconnection
         d.commitments.localChanges.proposed.collect {
           case add: UpdateAddHtlc => relayer ! RES_ADD_SETTLED(d.commitments.originChannels(add.id), add, HtlcResult.DisconnectedBeforeSigned(channelUpdate1))
@@ -1864,7 +1864,7 @@ class Channel(val nodeParams: NodeParams, val wallet: OnChainChannelFunder, val
     if (d.channelUpdate.channelFlags.isEnabled) {
       // if the channel isn't disabled we generate a new channel_update
       log.info("updating channel_update announcement (reason=disabled)")
-      val channelUpdate1 = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate(d), d.channelUpdate.cltvExpiryDelta, d.channelUpdate.htlcMinimumMsat, d.channelUpdate.feeBaseMsat, d.channelUpdate.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, enable = false)
+      val channelUpdate1 = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate(d), d.channelUpdate.cltvExpiryDelta, d.channelUpdate.htlcMinimumMsat, d.channelUpdate.feeBaseMsat, d.channelUpdate.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, isPrivate = !d.commitments.announceChannel, enable = false)
       // then we update the state and replay the request
       self forward c
       // we use goto() to fire transitions
@@ -1877,7 +1877,7 @@ class Channel(val nodeParams: NodeParams, val wallet: OnChainChannelFunder, val
   }
 
   private def handleUpdateRelayFeeDisconnected(c: CMD_UPDATE_RELAY_FEE, d: DATA_NORMAL) = {
-    val channelUpdate1 = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate(d), c.cltvExpiryDelta_opt.getOrElse(d.channelUpdate.cltvExpiryDelta), d.channelUpdate.htlcMinimumMsat, c.feeBase, c.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, enable = false)
+    val channelUpdate1 = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate(d), c.cltvExpiryDelta_opt.getOrElse(d.channelUpdate.cltvExpiryDelta), d.channelUpdate.htlcMinimumMsat, c.feeBase, c.feeProportionalMillionths, d.commitments.capacity.toMilliSatoshi, isPrivate = !d.commitments.announceChannel, enable = false)
     log.info(s"updating relay fees: prev={} next={}", d.channelUpdate.toStringShort, channelUpdate1.toStringShort)
     val replyTo = if (c.replyTo == ActorRef.noSender) sender() else c.replyTo
     replyTo ! RES_SUCCESS(c, d.channelId)

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

@@ -71,7 +71,7 @@ trait CommonFundingHandlers extends CommonHandlers {
     val scidForChannelUpdate = Helpers.scidForChannelUpdate(channelAnnouncement_opt = None, shortIds1.localAlias)
     log.info("using shortChannelId={} for initial channel_update", scidForChannelUpdate)
     val relayFees = getRelayFees(nodeParams, remoteNodeId, commitments)
-    val initialChannelUpdate = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate, nodeParams.channelConf.expiryDelta, commitments.remoteParams.htlcMinimum, relayFees.feeBase, relayFees.feeProportionalMillionths, commitments.capacity.toMilliSatoshi, enable = Helpers.aboveReserve(commitments))
+    val initialChannelUpdate = Announcements.makeChannelUpdate(nodeParams.chainHash, nodeParams.privateKey, remoteNodeId, scidForChannelUpdate, nodeParams.channelConf.expiryDelta, commitments.remoteParams.htlcMinimum, relayFees.feeBase, relayFees.feeProportionalMillionths, commitments.capacity.toMilliSatoshi, isPrivate = !commitments.announceChannel, enable = Helpers.aboveReserve(commitments))
     // we need to periodically re-send channel updates, otherwise channel will be considered stale and get pruned by network
     context.system.scheduler.scheduleWithFixedDelay(initialDelay = REFRESH_CHANNEL_UPDATE_INTERVAL, delay = REFRESH_CHANNEL_UPDATE_INTERVAL, receiver = self, message = BroadcastChannelUpdate(PeriodicRefresh))
     // used to get the final shortChannelId, used in announcements (if minDepth >= ANNOUNCEMENTS_MINCONF this event will fire instantly)

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

@@ -277,7 +277,6 @@ class PeerConnection(keyPair: KeyPair, conf: PeerConnection.Conf, switchboard: A
         stay()
 
       case Event(DelayedRebroadcast(rebroadcast), d: ConnectedData) =>
-
         val thisRemote = RemoteGossip(self, d.remoteNodeId)
 
         /**
@@ -290,6 +289,9 @@ class PeerConnection(keyPair: KeyPair, conf: PeerConnection.Conf, switchboard: A
           case (count, (msg, origins)) if !timestampInRange(msg, origins, d.gossipTimestampFilter) =>
             // the peer has set up a filter on timestamp and this message is out of range
             count
+          case (count, (u: ChannelUpdate, _)) if u.isPrivate =>
+            log.error("private channel update for scid={} was incorrectly added to staggered broadcast", u.shortChannelId)
+            count
           case (count, (msg, _)) =>
             d.transport ! msg
             count + 1

eclair-core/src/main/scala/fr/acinq/eclair/router/Announcements.scala

@@ -34,8 +34,8 @@ object Announcements {
   def nodeAnnouncementWitnessEncode(timestamp: TimestampSecond, nodeId: PublicKey, rgbColor: Color, alias: String, features: Features[Feature], addresses: List[NodeAddress], tlvStream: TlvStream[NodeAnnouncementTlv]): ByteVector =
     sha256(sha256(serializationResult(LightningMessageCodecs.nodeAnnouncementWitnessCodec.encode(features :: timestamp :: nodeId :: rgbColor :: alias :: addresses :: tlvStream :: HNil))))
 
-  def channelUpdateWitnessEncode(chainHash: ByteVector32, shortChannelId: ShortChannelId, timestamp: TimestampSecond, channelFlags: ChannelUpdate.ChannelFlags, cltvExpiryDelta: CltvExpiryDelta, htlcMinimumMsat: MilliSatoshi, feeBaseMsat: MilliSatoshi, feeProportionalMillionths: Long, htlcMaximumMsat: MilliSatoshi, tlvStream: TlvStream[ChannelUpdateTlv]): ByteVector =
-    sha256(sha256(serializationResult(LightningMessageCodecs.channelUpdateWitnessCodec.encode(chainHash :: shortChannelId :: timestamp :: channelFlags :: cltvExpiryDelta :: htlcMinimumMsat :: feeBaseMsat :: feeProportionalMillionths :: htlcMaximumMsat :: tlvStream :: HNil))))
+  def channelUpdateWitnessEncode(chainHash: ByteVector32, shortChannelId: ShortChannelId, timestamp: TimestampSecond, messageFlags: ChannelUpdate.MessageFlags, channelFlags: ChannelUpdate.ChannelFlags, cltvExpiryDelta: CltvExpiryDelta, htlcMinimumMsat: MilliSatoshi, feeBaseMsat: MilliSatoshi, feeProportionalMillionths: Long, htlcMaximumMsat: MilliSatoshi, tlvStream: TlvStream[ChannelUpdateTlv]): ByteVector =
+    sha256(sha256(serializationResult(LightningMessageCodecs.channelUpdateWitnessCodec.encode(chainHash :: shortChannelId :: timestamp :: messageFlags :: channelFlags :: cltvExpiryDelta :: htlcMinimumMsat :: feeBaseMsat :: feeProportionalMillionths :: htlcMaximumMsat :: tlvStream :: HNil))))
 
   def generateChannelAnnouncementWitness(chainHash: ByteVector32, shortChannelId: RealShortChannelId, localNodeId: PublicKey, remoteNodeId: PublicKey, localFundingKey: PublicKey, remoteFundingKey: PublicKey, features: Features[Feature]): ByteVector =
     if (isNode1(localNodeId, remoteNodeId)) {
@@ -118,15 +118,17 @@ object Announcements {
       u1.htlcMinimumMsat == u2.htlcMinimumMsat &&
       u1.htlcMaximumMsat == u2.htlcMaximumMsat
 
-  def makeChannelUpdate(chainHash: ByteVector32, nodeSecret: PrivateKey, remoteNodeId: PublicKey, shortChannelId: ShortChannelId, cltvExpiryDelta: CltvExpiryDelta, htlcMinimumMsat: MilliSatoshi, feeBaseMsat: MilliSatoshi, feeProportionalMillionths: Long, htlcMaximumMsat: MilliSatoshi, enable: Boolean = true, timestamp: TimestampSecond = TimestampSecond.now()): ChannelUpdate = {
+  def makeChannelUpdate(chainHash: ByteVector32, nodeSecret: PrivateKey, remoteNodeId: PublicKey, shortChannelId: ShortChannelId, cltvExpiryDelta: CltvExpiryDelta, htlcMinimumMsat: MilliSatoshi, feeBaseMsat: MilliSatoshi, feeProportionalMillionths: Long, htlcMaximumMsat: MilliSatoshi, isPrivate: Boolean = false, enable: Boolean = true, timestamp: TimestampSecond = TimestampSecond.now()): ChannelUpdate = {
+    val messageFlags = ChannelUpdate.MessageFlags(isPrivate)
     val channelFlags = ChannelUpdate.ChannelFlags(isNode1 = isNode1(nodeSecret.publicKey, remoteNodeId), isEnabled = enable)
-    val witness = channelUpdateWitnessEncode(chainHash, shortChannelId, timestamp, channelFlags, cltvExpiryDelta, htlcMinimumMsat, feeBaseMsat, feeProportionalMillionths, htlcMaximumMsat, TlvStream.empty)
+    val witness = channelUpdateWitnessEncode(chainHash, shortChannelId, timestamp, messageFlags, channelFlags, cltvExpiryDelta, htlcMinimumMsat, feeBaseMsat, feeProportionalMillionths, htlcMaximumMsat, TlvStream.empty)
     val sig = Crypto.sign(witness, nodeSecret)
     ChannelUpdate(
       signature = sig,
       chainHash = chainHash,
       shortChannelId = shortChannelId,
       timestamp = timestamp,
+      messageFlags = messageFlags,
       channelFlags = channelFlags,
       cltvExpiryDelta = cltvExpiryDelta,
       htlcMinimumMsat = htlcMinimumMsat,
@@ -139,7 +141,7 @@ object Announcements {
   def updateScid(nodeSecret: PrivateKey, u: ChannelUpdate, scid: ShortChannelId): ChannelUpdate = {
     // NB: we don't update the timestamp as we're not changing any parameter.
     val u1 = u.copy(shortChannelId = scid)
-    val witness = channelUpdateWitnessEncode(u.chainHash, scid, u.timestamp, u.channelFlags, u.cltvExpiryDelta, u.htlcMinimumMsat, u.feeBaseMsat, u.feeProportionalMillionths, u.htlcMaximumMsat, u.tlvStream)
+    val witness = channelUpdateWitnessEncode(u.chainHash, scid, u.timestamp, u.messageFlags, u.channelFlags, u.cltvExpiryDelta, u.htlcMinimumMsat, u.feeBaseMsat, u.feeProportionalMillionths, u.htlcMaximumMsat, u.tlvStream)
     val sig = Crypto.sign(witness, nodeSecret)
     u1.copy(signature = sig)
   }
@@ -158,7 +160,7 @@ object Announcements {
   }
 
   def checkSig(upd: ChannelUpdate, nodeId: PublicKey): Boolean = {
-    val witness = channelUpdateWitnessEncode(upd.chainHash, upd.shortChannelId, upd.timestamp, upd.channelFlags, upd.cltvExpiryDelta, upd.htlcMinimumMsat, upd.feeBaseMsat, upd.feeProportionalMillionths, upd.htlcMaximumMsat, upd.tlvStream)
+    val witness = channelUpdateWitnessEncode(upd.chainHash, upd.shortChannelId, upd.timestamp, upd.messageFlags, upd.channelFlags, upd.cltvExpiryDelta, upd.htlcMinimumMsat, upd.feeBaseMsat, upd.feeProportionalMillionths, upd.htlcMaximumMsat, upd.tlvStream)
     verifySignature(witness, upd.signature, nodeId)
   }
 }

eclair-core/src/main/scala/fr/acinq/eclair/router/Sync.scala

@@ -386,7 +386,7 @@ object Sync {
   def getChecksum(u: ChannelUpdate): Long = {
     import u._
 
-    val data = serializationResult(LightningMessageCodecs.channelUpdateChecksumCodec.encode(chainHash :: shortChannelId :: channelFlags :: cltvExpiryDelta :: htlcMinimumMsat :: feeBaseMsat :: feeProportionalMillionths :: htlcMaximumMsat :: HNil))
+    val data = serializationResult(LightningMessageCodecs.channelUpdateChecksumCodec.encode(chainHash :: shortChannelId :: messageFlags :: channelFlags :: cltvExpiryDelta :: htlcMinimumMsat :: feeBaseMsat :: feeProportionalMillionths :: htlcMaximumMsat :: HNil))
     crc32c(data)
   }