Use warning messages for connection issues (#1863)

lightning/bolts#834 recommends sending
warning messages instead of connection-level errors in some cases, which
avoids unnecessary channel closure.

Author: t-bast

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

@@ -1701,18 +1701,19 @@ class Channel(val nodeParams: NodeParams, val wallet: EclairWallet, remoteNodeId
     // a channel_reestablish when reconnecting a channel that recently got confirmed, and instead send a funding_locked
     // first and then go silent. This is due to a race condition on their side, so we trigger a reconnection, hoping that
     // we will eventually receive their channel_reestablish.
-    case Event(_: FundingLocked, _) =>
+    case Event(_: FundingLocked, d) =>
       log.warning("received funding_locked before channel_reestablish (known lnd bug): disconnecting...")
-      peer ! Peer.Disconnect(remoteNodeId)
-      stay
+      // NB: we use a small delay to ensure we've sent our warning before disconnecting.
+      context.system.scheduler.scheduleOnce(2 second, peer, Peer.Disconnect(remoteNodeId))
+      stay sending Warning(d.channelId, "spec violation: you sent funding_locked before channel_reestablish")
 
     // This handler is a workaround for an issue in lnd similar to the one above: they sometimes send announcement_signatures
     // before channel_reestablish, which is a minor spec violation. It doesn't halt the channel, we can simply postpone
     // that message.
-    case Event(remoteAnnSigs: AnnouncementSignatures, _) =>
+    case Event(remoteAnnSigs: AnnouncementSignatures, d) =>
       log.warning("received announcement_signatures before channel_reestablish (known lnd bug): delaying...")
       context.system.scheduler.scheduleOnce(5 seconds, self, remoteAnnSigs)
-      stay
+      stay sending Warning(d.channelId, "spec violation: you sent announcement_signatures before channel_reestablish")
 
     case Event(ProcessCurrentBlockCount(c), d: HasCommitments) => handleNewBlock(c, d)
 

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

@@ -106,7 +106,7 @@ class Peer(val nodeParams: NodeParams, remoteNodeId: PublicKey, wallet: EclairWa
         stay
 
       case Event(warning: Warning, _: ConnectedData) =>
-        log.warning("peer sent warning: {}", warning.channelId, warning.toAscii)
+        log.warning("peer sent warning: {}", warning.toAscii)
         // NB: we don't forward warnings to the channel actors, they shouldn't take any automatic action.
         // It's up to the node operator to decide what to do to address the warning.
         stay
@@ -318,7 +318,7 @@ class Peer(val nodeParams: NodeParams, remoteNodeId: PublicKey, wallet: EclairWa
   }
 
   def replyUnknownChannel(peerConnection: ActorRef, unknownChannelId: ByteVector32): Unit = {
-    val msg = Error(unknownChannelId, UNKNOWN_CHANNEL_MESSAGE)
+    val msg = Warning(unknownChannelId, "unknown channel")
     logMessage(msg, "OUT")
     peerConnection ! msg
   }
@@ -361,10 +361,7 @@ class Peer(val nodeParams: NodeParams, remoteNodeId: PublicKey, wallet: EclairWa
 
 object Peer {
 
-  // @formatter:off
   val CHANNELID_ZERO: ByteVector32 = ByteVector32.Zeroes
-  val UNKNOWN_CHANNEL_MESSAGE: ByteVector = ByteVector.view("unknown channel".getBytes())
-  // @formatter:on
 
   trait ChannelFactory {
     def spawn(context: ActorContext, remoteNodeId: PublicKey, origin_opt: Option[ActorRef]): ActorRef

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

@@ -24,7 +24,6 @@ import fr.acinq.eclair.Logs.LogCategory
 import fr.acinq.eclair.crypto.Noise.KeyPair
 import fr.acinq.eclair.crypto.TransportHandler
 import fr.acinq.eclair.io.Monitoring.{Metrics, Tags}
-import fr.acinq.eclair.io.Peer.CHANNELID_ZERO
 import fr.acinq.eclair.remote.EclairInternalsSerializer.RemoteTypes
 import fr.acinq.eclair.router.Router._
 import fr.acinq.eclair.wire.protocol
@@ -195,6 +194,7 @@ class PeerConnection(keyPair: KeyPair, conf: PeerConnection.Conf, switchboard: A
           d.transport ! Pong(ByteVector.fill(pongLength)(0.toByte))
         } else {
           log.warning(s"ignoring invalid ping with pongLength=${ping.pongLength}")
+          d.transport ! Warning(s"invalid pong length (${ping.pongLength})")
         }
         stay
 
@@ -207,8 +207,9 @@ class PeerConnection(keyPair: KeyPair, conf: PeerConnection.Conf, switchboard: A
             log.debug(s"received pong with latency=$latency")
             cancelTimer(PingTimeout.toString())
           // we don't need to call scheduleNextPing here, the next ping was already scheduled when we received that pong
-          case None =>
-            log.debug(s"received unexpected pong with size=${data.length}")
+          case _ =>
+            log.debug(s"received unexpected pong with length=${data.length}")
+            d.transport ! Warning(s"invalid pong with length=${data.length}")
         }
         stay using d.copy(expectedPong_opt = None)
 
@@ -264,6 +265,7 @@ class PeerConnection(keyPair: KeyPair, conf: PeerConnection.Conf, switchboard: A
         d.transport ! TransportHandler.ReadAck(msg)
         if (msg.chainHash != d.chainHash) {
           log.warning("received gossip_timestamp_range message for chain {}, we're on {}", msg.chainHash, d.chainHash)
+          d.transport ! Warning(s"invalid gossip_timestamp_range chain (${msg.chainHash})")
           stay
         } else {
           log.info(s"setting up gossipTimestampFilter=$msg")
@@ -306,16 +308,16 @@ class PeerConnection(keyPair: KeyPair, conf: PeerConnection.Conf, switchboard: A
               case _ => "unknown"
             }
             log.error(s"peer sent us a routing message with invalid sig: r=$r bin=$bin")
-            // for now we just return an error, maybe ban the peer in the future?
+            // for now we just send a warning, maybe ban the peer in the future?
             // TODO: this doesn't actually disconnect the peer, once we introduce peer banning we should actively disconnect
-            d.transport ! Error(CHANNELID_ZERO, ByteVector.view(s"bad announcement sig! bin=$bin".getBytes()))
+            d.transport ! Warning(s"invalid announcement sig (bin=$bin)")
             d.behavior
           case GossipDecision.InvalidAnnouncement(c) =>
             // they seem to be sending us fake announcements?
             log.error(s"couldn't find funding tx with valid scripts for shortChannelId=${c.shortChannelId}")
-            // for now we just return an error, maybe ban the peer in the future?
+            // for now we just send a warning, maybe ban the peer in the future?
             // TODO: this doesn't actually disconnect the peer, once we introduce peer banning we should actively disconnect
-            d.transport ! Error(CHANNELID_ZERO, ByteVector.view(s"couldn't verify channel! shortChannelId=${c.shortChannelId}".getBytes()))
+            d.transport ! Warning(s"invalid announcement, couldn't verify channel (shortChannelId=${c.shortChannelId})")
             d.behavior
           case GossipDecision.ChannelClosed(_) =>
             if (d.behavior.ignoreNetworkAnnouncement) {
@@ -325,6 +327,7 @@ class PeerConnection(keyPair: KeyPair, conf: PeerConnection.Conf, switchboard: A
               d.behavior.copy(fundingTxAlreadySpentCount = d.behavior.fundingTxAlreadySpentCount + 1)
             } else {
               log.warning(s"peer sent us too many channel announcements with funding tx already spent (count=${d.behavior.fundingTxAlreadySpentCount + 1}), ignoring network announcements for $IGNORE_NETWORK_ANNOUNCEMENTS_PERIOD")
+              d.transport ! Warning("too many channel announcements with funding tx already spent, please check your bitcoin node")
               setTimer(ResumeAnnouncements.toString, ResumeAnnouncements, IGNORE_NETWORK_ANNOUNCEMENTS_PERIOD, repeat = false)
               d.behavior.copy(fundingTxAlreadySpentCount = d.behavior.fundingTxAlreadySpentCount + 1, ignoreNetworkAnnouncement = true)
             }

eclair-core/src/test/scala/fr/acinq/eclair/io/PeerConnectionSpec.scala

@@ -231,6 +231,7 @@ class PeerConnectionSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike wi
     val ping = Ping(Int.MaxValue, randomBytes(127))
     transport.send(peerConnection, ping)
     transport.expectMsg(TransportHandler.ReadAck(ping))
+    assert(transport.expectMsgType[Warning].channelId === Peer.CHANNELID_ZERO)
     transport.expectNoMsg()
   }
 
@@ -332,8 +333,13 @@ class PeerConnectionSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike wi
       router.send(peerConnection, GossipDecision.ChannelClosed(c))
     }
     // peer will temporary ignore announcements coming from bob
+    var warningSent = false
     for (ann <- channels ++ updates) {
       transport.send(peerConnection, ann)
+      if (!warningSent) {
+        transport.expectMsgType[Warning]
+        warningSent = true
+      }
       transport.expectMsg(TransportHandler.ReadAck(ann))
     }
     router.expectNoMsg(1 second)
@@ -354,16 +360,16 @@ class PeerConnectionSpec extends TestKitBaseClass with FixtureAnyFunSuiteLike wi
     // now let's assume that the router isn't happy with those channels because the announcement is invalid
     router.send(peerConnection, GossipDecision.InvalidAnnouncement(channels(0)))
     // peer will return a connection-wide error, including the hex-encoded representation of the bad message
-    val error1 = transport.expectMsgType[Error]
-    assert(error1.channelId === Peer.CHANNELID_ZERO)
-    assert(new String(error1.data.toArray).startsWith("couldn't verify channel! shortChannelId="))
+    val warn1 = transport.expectMsgType[Warning]
+    assert(warn1.channelId === Peer.CHANNELID_ZERO)
+    assert(new String(warn1.data.toArray).startsWith("invalid announcement, couldn't verify channel"))
 
     // let's assume that one of the sigs were invalid
     router.send(peerConnection, GossipDecision.InvalidSignature(channels(0)))
     // peer will return a connection-wide error, including the hex-encoded representation of the bad message
-    val error2 = transport.expectMsgType[Error]
-    assert(error2.channelId === Peer.CHANNELID_ZERO)
-    assert(new String(error2.data.toArray).startsWith("bad announcement sig! bin=0100"))
+    val warn2 = transport.expectMsgType[Warning]
+    assert(warn2.channelId === Peer.CHANNELID_ZERO)
+    assert(new String(warn2.data.toArray).startsWith("invalid announcement sig"))
   }
 
 }