[FIX] Add test case for rewind with lack of parent

input-output-hk · Sep 3, 2020 · af48fb8 · af48fb8
1 parent dc859ad
commit af48fb8
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Showing 2 changed files with 36 additions and 8 deletions.
diff --git a/src/main/scala/io/iohk/ethereum/blockchain/sync/FastSync.scala b/src/main/scala/io/iohk/ethereum/blockchain/sync/FastSync.scala
@@ -296,10 +296,8 @@ class FastSync(
       blockchain.getTotalDifficultyByHash(header.parentHash).toRight(ParentDifficultyNotFound(header))
     }
 
-    private def handleRewind(header: BlockHeader, peer: Option[Peer], N: Int): Unit = {
-      peer.foreach(p =>
-        blacklist(p.id, blacklistDuration, "block header validation failed")
-      )
+    private def handleRewind(header: BlockHeader, peer: Peer, N: Int): Unit = {
+      blacklist(peer.id, blacklistDuration, "block header validation failed")
       if (header.number <= syncState.safeDownloadTarget) {
         discardLastBlocks(header.number, N)
         syncState = syncState.updateDiscardedBlocks(header, N)
@@ -317,17 +315,18 @@ class FastSync(
       if (checkHeadersChain(headers)) {
         processHeaders(peer, headers) match {
           case ParentDifficultyNotFound(header) =>
-            // We could end in wrong fork and get blocked. Correct course of action is to not blacklist anyone and not
-            // rewind fast sync a litte
+            // We could end in wrong fork and get blocked so we should rewind our state a little
+            // we blacklist peer just in case we got malicious peer which would send us bad blocks, forcing us to rollback
+            // to genesis
             log.info("Parent difficulty not found for block {}, not processing rest of headers", header.idTag)
-            handleRewind(header, None, syncConfig.fastSyncBlockValidationN)
+            handleRewind(header, peer, syncConfig.fastSyncBlockValidationN)
           case HeadersProcessingFinished =>
             processSyncing()
           case ImportedTargetBlock  =>
             updateTargetBlock(ImportedLastBlock)
           case ValidationFailed(header, peerToBlackList) =>
             log.info(s"validation fo header ${header.idTag} failed")
-            handleRewind(header, Some(peerToBlackList), syncConfig.fastSyncBlockValidationN)
+            handleRewind(header, peerToBlackList, syncConfig.fastSyncBlockValidationN)
         }
       } else {
         blacklist(peer.id, blacklistDuration, "error in block headers response")

diff --git a/src/test/scala/io/iohk/ethereum/blockchain/sync/SyncControllerSpec.scala b/src/test/scala/io/iohk/ethereum/blockchain/sync/SyncControllerSpec.scala
@@ -173,6 +173,35 @@ class SyncControllerSpec extends FlatSpec with Matchers with BeforeAndAfter with
     syncState.receiptsQueue.isEmpty shouldBe true
   }
 
+  it should "rewind fast-sync state if received header have no known parent" in new TestSetup() {
+
+    val bestBlockNumber = defaultExpectedTargetBlock - 1
+
+    startWithState(defaultState.copy(bestBlockHeaderNumber = bestBlockNumber))
+
+    Thread.sleep(1.seconds.toMillis)
+
+    syncController ! SyncController.Start
+
+    updateHandshakedPeers(HandshakedPeers(singlePeer))
+
+    sendBlockHeaders(
+      defaultTargetBlockHeader.number,
+      Seq(defaultTargetBlockHeader.copy(number = defaultExpectedTargetBlock, parentHash = ByteString(0,1))),
+      peer1,
+      defaultExpectedTargetBlock - bestBlockNumber)
+
+    persistState()
+
+    val syncState = storagesInstance.storages.fastSyncStateStorage.getSyncState().get
+
+    syncState.bestBlockHeaderNumber shouldBe (bestBlockNumber - syncConfig.fastSyncBlockValidationN)
+    syncState.nextBlockToFullyValidate shouldBe (bestBlockNumber - syncConfig.fastSyncBlockValidationN + 1)
+    syncState.blockBodiesQueue.isEmpty shouldBe true
+    syncState.receiptsQueue.isEmpty shouldBe true
+  }
+
+
   it should "not change best block after receiving faraway block" in new TestSetup(_validators = new Mocks.MockValidatorsAlwaysSucceed {
     override val blockHeaderValidator: BlockHeaderValidator = { (blockHeader, getBlockHeaderByHash) => Left(HeaderParentNotFoundError) }
   }) {