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Add private flag to channel updates (#2362)
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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
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t-bast authored Nov 4, 2022
1 parent c385ca2 commit a8389a0
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Showing 23 changed files with 85 additions and 56 deletions.
Original file line number Diff line number Diff line change
Expand Up @@ -635,7 +635,7 @@ 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
}
Expand Down Expand Up @@ -668,7 +668,7 @@ 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()
}
Expand All @@ -690,7 +690,7 @@ 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)
Expand All @@ -699,7 +699,7 @@ 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)
Expand All @@ -723,7 +723,7 @@ 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))
Expand Down Expand Up @@ -1865,7 +1865,7 @@ 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
Expand All @@ -1878,7 +1878,7 @@ 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)
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -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)

/**
Expand All @@ -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.dontForward =>
log.error("private channel update for scid={} was incorrectly added to staggered broadcast", u.shortChannelId)
count
case (count, (msg, _)) =>
d.transport ! msg
count + 1
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -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)) {
Expand Down Expand Up @@ -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,
Expand All @@ -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)
}
Expand All @@ -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)
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -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)
}

Expand Down
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