Handle fees increases when channel is OFFLINE

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

@@ -1428,6 +1428,16 @@ class Channel(val nodeParams: NodeParams, val wallet: EclairWallet, remoteNodeId
       // -> in CLOSING we either have mutual closed (so no more htlcs), or already have unilaterally closed (so no action required), and we can't be in OFFLINE state anyway
       handleLocalError(HtlcTimedout(d.channelId, d.commitments.timedoutOutgoingHtlcs(count)), d, Some(c))
 
+    case Event(c@CurrentFeerates(feeratesPerKw), d: HasCommitments) =>
+      val networkFeeratePerKw = feeratesPerKw.blocks_2
+      val currentFeeratePerKw = d.commitments.localCommit.spec.feeratePerKw
+      // if the fees are too high we risk to not be able to confirm our current commitment
+      if(networkFeeratePerKw > currentFeeratePerKw && Helpers.isFeeDiffTooHigh(currentFeeratePerKw, networkFeeratePerKw, nodeParams.maxFeerateMismatch)){
+        handleLocalError(FeerateTooDifferent(d.channelId, localFeeratePerKw = currentFeeratePerKw, remoteFeeratePerKw = networkFeeratePerKw), d, Some(c))
+      } else {
+        stay
+      }
+
     case Event(c: CMD_ADD_HTLC, d: DATA_NORMAL) => handleAddDisconnected(c, d)
 
     case Event(CMD_UPDATE_RELAY_FEE(feeBaseMsat, feeProportionalMillionths), d: DATA_NORMAL) =>

eclair-core/src/test/scala/fr/acinq/eclair/channel/states/e/OfflineStateSpec.scala

@@ -20,14 +20,15 @@ import akka.actor.Status
 import java.util.UUID
 
 import akka.testkit.TestProbe
-import fr.acinq.bitcoin.Crypto.{PrivateKey}
+import fr.acinq.bitcoin.Crypto.PrivateKey
 import fr.acinq.bitcoin.{ByteVector32, ScriptFlags, Transaction}
-import fr.acinq.eclair.blockchain.{PublishAsap, WatchEventSpent}
+import fr.acinq.eclair.blockchain.fee.FeeratesPerKw
+import fr.acinq.eclair.blockchain.{CurrentFeerates, PublishAsap, WatchEventSpent}
 import fr.acinq.eclair.channel._
 import fr.acinq.eclair.channel.states.StateTestsHelperMethods
 import fr.acinq.eclair.router.Announcements
 import fr.acinq.eclair.wire._
-import fr.acinq.eclair.{TestConstants, TestkitBaseClass, randomBytes32}
+import fr.acinq.eclair.{Globals, TestConstants, TestkitBaseClass, randomBytes32}
 import org.scalatest.Outcome
 
 import scala.concurrent.duration._
@@ -391,4 +392,48 @@ class OfflineStateSpec extends TestkitBaseClass with StateTestsHelperMethods {
     assert(Announcements.isEnabled(update.channelUpdate.channelFlags) == false)
   }
 
+  test("handle feerate changes while offline (funder scenario)") { f =>
+    import f._
+    val sender = TestProbe()
+
+    // we simulate a disconnection
+    sender.send(alice, INPUT_DISCONNECTED)
+    sender.send(bob, INPUT_DISCONNECTED)
+    awaitCond(alice.stateName == OFFLINE)
+    awaitCond(bob.stateName == OFFLINE)
+
+    val aliceStateData = alice.stateData.asInstanceOf[DATA_NORMAL]
+    val aliceCommitTx = aliceStateData.commitments.localCommit.publishableTxs.commitTx.tx
+
+    val localFeeratePerKw = aliceStateData.commitments.localCommit.spec.feeratePerKw
+    val tooHighFeeratePerKw = ((TestConstants.Alice.nodeParams.maxFeerateMismatch + 6) * localFeeratePerKw).toLong
+    val highFeerate = FeeratesPerKw.single(tooHighFeeratePerKw)
+
+    // alice is funder
+    sender.send(alice, CurrentFeerates(highFeerate))
+    alice2blockchain.expectMsg(PublishAsap(aliceCommitTx))
+  }
+
+  test("handle feerate changes while offline (fundee scenario)") { f =>
+    import f._
+    val sender = TestProbe()
+
+    // we simulate a disconnection
+    sender.send(alice, INPUT_DISCONNECTED)
+    sender.send(bob, INPUT_DISCONNECTED)
+    awaitCond(alice.stateName == OFFLINE)
+    awaitCond(bob.stateName == OFFLINE)
+
+    val bobStateData = bob.stateData.asInstanceOf[DATA_NORMAL]
+    val bobCommitTx = bobStateData.commitments.localCommit.publishableTxs.commitTx.tx
+
+    val localFeeratePerKw = bobStateData.commitments.localCommit.spec.feeratePerKw
+    val tooHighFeeratePerKw = ((TestConstants.Bob.nodeParams.maxFeerateMismatch + 6) * localFeeratePerKw).toLong
+    val highFeerate = FeeratesPerKw.single(tooHighFeeratePerKw)
+
+    // bob is fundee
+    sender.send(bob, CurrentFeerates(highFeerate))
+    bob2blockchain.expectMsg(PublishAsap(bobCommitTx))
+  }
+
 }