Merge pull request #90 from akroma-project/reorg_error_vs_warning

feat(blockchain): prevent reorg greater then 64 blocks)

core/blockchain.go

@@ -1555,11 +1555,10 @@ func (bc *BlockChain) reorg(oldBlock, newBlock *types.Block) error {
 	}
 	// Ensure the user sees large reorgs
 	if len(oldChain) > 0 && len(newChain) > 0 {
-		logFn := log.Debug
-		if len(oldChain) > 63 {
-			logFn = log.Warn
+		if len(oldChain) > 64 {
+			return fmt.Errorf("Chain is too long for reorg")
 		}
-		logFn("Chain split detected", "number", commonBlock.Number(), "hash", commonBlock.Hash(),
+		log.Debug("Chain split detected", "number", commonBlock.Number(), "hash", commonBlock.Hash(),
 			"drop", len(oldChain), "dropfrom", oldChain[0].Hash(), "add", len(newChain), "addfrom", newChain[0].Hash())
 	} else {
 		log.Error("Impossible reorg, please file an issue", "oldnum", oldBlock.Number(), "oldhash", oldBlock.Hash(), "newnum", newBlock.Number(), "newhash", newBlock.Hash())

core/blockchain_test.go

@@ -374,8 +374,8 @@ func TestReorgShortBlocks(t *testing.T)  { testReorgShort(t, true) }
 func testReorgShort(t *testing.T, full bool) {
 	// Create a long easy chain vs. a short heavy one. Due to difficulty adjustment
 	// we need a fairly long chain of blocks with different difficulties for a short
-	// one to become heavyer than a long one. The 96 is an empirical value.
-	easy := make([]int64, 96)
+	// one to become heavyer than a long one. The 64 is an empirical value.
+	easy := make([]int64, 64)
 	for i := 0; i < len(easy); i++ {
 		easy[i] = 60
 	}