[Fix] Fix handling of empty recipts int fast sync

src/main/scala/io/iohk/ethereum/blockchain/sync/FastSync.scala

@@ -16,6 +16,7 @@ import io.iohk.ethereum.network.Peer
 import io.iohk.ethereum.network.p2p.messages.PV62._
 import io.iohk.ethereum.network.p2p.messages.PV63.MptNodeEncoders._
 import io.iohk.ethereum.network.p2p.messages.PV63._
+import io.iohk.ethereum.utils.ByteStringUtils
 import io.iohk.ethereum.utils.Config.SyncConfig
 import org.bouncycastle.util.encoders.Hex
 
@@ -360,35 +361,36 @@ class FastSync(
     }
 
     private def handleReceipts(peer: Peer, requestedHashes: Seq[ByteString], receipts: Seq[Seq[Receipt]]) = {
-      validateReceipts(requestedHashes, receipts) match {
-        case ReceiptsValidationResult.Valid(blockHashesWithReceipts) =>
-          blockHashesWithReceipts.map { case (hash, receiptsForBlock) =>
-            blockchain.storeReceipts(hash, receiptsForBlock)
-          }.reduce(_.and(_))
-            .commit()
-
-          val receivedHashes = blockHashesWithReceipts.unzip._1
-          updateBestBlockIfNeeded(receivedHashes)
-
-          if (receipts.isEmpty) {
-            val reason = s"got empty receipts for known hashes: ${requestedHashes.map(h => Hex.toHexString(h.toArray[Byte]))}"
-            blacklist(peer.id, blacklistDuration, reason)
-          }
-
-          val remainingReceipts = requestedHashes.drop(receipts.size)
-          if (remainingReceipts.nonEmpty) {
-            syncState = syncState.enqueueReceipts(remainingReceipts)
-          }
+      if (receipts.isEmpty) {
+        val reason = s"got empty receipts for known hashes: ${requestedHashes.map(ByteStringUtils.hash2string)}"
+        blacklist(peer.id, blacklistDuration, reason)
+        syncState = syncState.enqueueReceipts(requestedHashes)
+      } else {
+        validateReceipts(requestedHashes, receipts) match {
+          case ReceiptsValidationResult.Valid(blockHashesWithReceipts) =>
+            blockHashesWithReceipts.map { case (hash, receiptsForBlock) =>
+              blockchain.storeReceipts(hash, receiptsForBlock)
+            }.reduce(_.and(_))
+              .commit()
+
+            val receivedHashes = blockHashesWithReceipts.unzip._1
+            updateBestBlockIfNeeded(receivedHashes)
+
+            val remainingReceipts = requestedHashes.drop(receipts.size)
+            if (remainingReceipts.nonEmpty) {
+              syncState = syncState.enqueueReceipts(remainingReceipts)
+            }
 
-        case ReceiptsValidationResult.Invalid(error) =>
-          val reason =
-            s"got invalid receipts for known hashes: ${requestedHashes.map(h => Hex.toHexString(h.toArray[Byte]))}" +
-              s" due to: $error"
-          blacklist(peer.id, blacklistDuration, reason)
-          syncState = syncState.enqueueReceipts(requestedHashes)
+          case ReceiptsValidationResult.Invalid(error) =>
+            val reason =
+              s"got invalid receipts for known hashes: ${requestedHashes.map(h => Hex.toHexString(h.toArray[Byte]))}" +
+                s" due to: $error"
+            blacklist(peer.id, blacklistDuration, reason)
+            syncState = syncState.enqueueReceipts(requestedHashes)
 
-        case ReceiptsValidationResult.DbError =>
-          redownloadBlockchain()
+          case ReceiptsValidationResult.DbError =>
+            redownloadBlockchain()
+        }
       }
 
       processSyncing()

src/test/scala/io/iohk/ethereum/blockchain/sync/SyncControllerSpec.scala

@@ -145,6 +145,68 @@ class SyncControllerSpec extends AnyFlatSpec with Matchers with BeforeAndAfter w
     peerMessageBus.expectMsg(Subscribe(MessageClassifier(Set(BlockHeaders.code), PeerSelector.WithId(peer1.id))))
   }
 
+  it should "gracefully handle receiving empty receipts while syncing" in new TestSetup() {
+
+    val newSafeTarget   = defaultExpectedTargetBlock + syncConfig.fastSyncBlockValidationX
+    val bestBlockNumber = defaultExpectedTargetBlock
+    val firstNewBlock = bestBlockNumber + 1
+
+    startWithState(defaultState.copy(
+      bestBlockHeaderNumber = bestBlockNumber,
+      safeDownloadTarget = newSafeTarget)
+    )
+
+    Thread.sleep(1.seconds.toMillis)
+
+    syncController ! SyncController.Start
+
+    val handshakedPeers = HandshakedPeers(singlePeer)
+    updateHandshakedPeers(handshakedPeers)
+    etcPeerManager.setAutoPilot(new AutoPilot {
+      def run(sender: ActorRef, msg: Any): AutoPilot = {
+        if (msg == EtcPeerManagerActor.GetHandshakedPeers) {
+          sender ! handshakedPeers
+        }
+
+        this
+      }
+    })
+
+    val watcher = TestProbe()
+    watcher.watch(syncController)
+
+    val newBlocks = getHeaders(firstNewBlock, syncConfig.blockHeadersPerRequest)
+    val newReceipts = newBlocks.map(_.hash).map(_ => Seq.empty[Receipt])
+    val newBodies = newBlocks.map(_ => BlockBody.empty)
+
+    //wait for peers throttle
+    Thread.sleep(syncConfig.fastSyncThrottle.toMillis)
+    sendBlockHeaders(firstNewBlock, newBlocks, peer1, newBlocks.size)
+
+    Thread.sleep(syncConfig.fastSyncThrottle.toMillis)
+    sendNewTargetBlock(defaultTargetBlockHeader.copy(number = defaultTargetBlockHeader.number + 1), peer1, peer1Status, handshakedPeers)
+
+    Thread.sleep(1.second.toMillis)
+    sendReceipts(newBlocks.map(_.hash), Seq(), peer1)
+
+    // Peer will be blacklisted for empty response, so wait he is blacklisted
+    Thread.sleep(2.second.toMillis)
+    sendReceipts(newBlocks.map(_.hash), newReceipts, peer1)
+
+    Thread.sleep(syncConfig.fastSyncThrottle.toMillis)
+    sendBlockBodies(newBlocks.map(_.hash), newBodies, peer1)
+
+    Thread.sleep(syncConfig.fastSyncThrottle.toMillis)
+    sendNodes(Seq(defaultTargetBlockHeader.stateRoot), Seq(defaultStateMptLeafWithAccount), peer1)
+
+    //switch to regular download
+    etcPeerManager.expectMsg(EtcPeerManagerActor.SendMessage(
+      GetBlockHeaders(Left(defaultTargetBlockHeader.number + 1), syncConfig.blockHeadersPerRequest, 0, reverse = false),
+      peer1.id))
+    peerMessageBus.expectMsg(Subscribe(MessageClassifier(Set(BlockHeaders.code), PeerSelector.WithId(peer1.id))))
+  }
+
+
   it should "handle blocks that fail validation" in new TestSetup(_validators = new Mocks.MockValidatorsAlwaysSucceed {
     override val blockHeaderValidator: BlockHeaderValidator = { (blockHeader, getBlockHeaderByHash) => Left(HeaderPoWError) }
   }) {
@@ -444,11 +506,12 @@ class SyncControllerSpec extends AnyFlatSpec with Matchers with BeforeAndAfter w
     peerMessageBus.expectMsg(Unsubscribe())
 
     // response timeout
-    Thread.sleep(2.seconds.toMillis)
-    etcPeerManager.expectNoMessage()
+    Thread.sleep(1.seconds.toMillis)
+
+    etcPeerManager.expectNoMessage(1.second)
 
     // wait for blacklist timeout
-    Thread.sleep(6.seconds.toMillis)
+    Thread.sleep(2.seconds.toMillis)
 
     // peer should not be blacklisted anymore
     etcPeerManager.expectMsg(EtcPeerManagerActor.SendMessage(GetNodeData(Seq(defaultTargetBlockHeader.stateRoot)), peer1.id))
@@ -577,7 +640,8 @@ class SyncControllerSpec extends AnyFlatSpec with Matchers with BeforeAndAfter w
       minPeersToChooseTargetBlock = 1,
       peersScanInterval = 500.milliseconds,
       redownloadMissingStateNodes = false,
-      fastSyncBlockValidationX = 10
+      fastSyncBlockValidationX = 10,
+      blacklistDuration = 1.second
     )
 
     lazy val syncController = TestActorRef(Props(new SyncController(

src/test/scala/io/iohk/ethereum/consensus/ethash/EthashUtilsSpec.scala

@@ -2,18 +2,20 @@ package io.iohk.ethereum.consensus.ethash
 
 import akka.util.ByteString
 import io.iohk.ethereum.crypto.kec256
-import org.scalacheck.Arbitrary
+import org.scalacheck.Gen
 import org.bouncycastle.util.encoders.Hex
 import org.scalatestplus.scalacheck.ScalaCheckPropertyChecks
 import org.scalatest.flatspec.AnyFlatSpec
 import org.scalatest.matchers.should.Matchers
 
+import scala.annotation.tailrec
+
 class EthashUtilsSpec extends AnyFlatSpec with Matchers with ScalaCheckPropertyChecks {
 
   import io.iohk.ethereum.consensus.ethash.EthashUtils._
 
   "Ethash" should "generate correct hash" in {
-    forAll(Arbitrary.arbitrary[Long].filter(_ < 15000000)) { blockNumber =>
+    forAll(Gen.choose[Long](0, 15000000L)) { blockNumber =>
       seed(epoch(blockNumber)) shouldBe seedForBlockReference(blockNumber)
     }
   }
@@ -115,13 +117,15 @@ class EthashUtilsSpec extends AnyFlatSpec with Matchers with ScalaCheckPropertyC
   }
 
   def seedForBlockReference(blockNumber: BigInt): ByteString = {
-    if (blockNumber < EPOCH_LENGTH) {
-      //wrong version from YP:
-      //ByteString(kec256(Hex.decode("00" * 32)))
-      //working version:
-      ByteString(Hex.decode("00" * 32))
-    } else {
-      kec256(seedForBlockReference(blockNumber - EPOCH_LENGTH))
+    @tailrec
+    def go(current: BigInt, currentHash: ByteString): ByteString = {
+      if (current < EPOCH_LENGTH) {
+        currentHash
+      } else {
+        go(current - EPOCH_LENGTH, kec256(currentHash))
+      }
     }
+
+    go(blockNumber, ByteString(Hex.decode("00" * 32)))
   }
 }