From dba64ca903617ec5c1ed6be91f63b719dd9a8cd3 Mon Sep 17 00:00:00 2001
From: Martin Holst Swende <martin@swende.se>
Date: Wed, 17 Oct 2018 19:47:10 +0200
Subject: [PATCH] core/blockchain, downloader: abort early on sidechain import
 with bad blocks

---
 core/blockchain.go           | 8 ++++++++
 eth/downloader/downloader.go | 4 ++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/core/blockchain.go b/core/blockchain.go
index f4a818f4c0..7ad13cb388 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -1144,12 +1144,17 @@ func (bc *BlockChain) insertChain(chain types.Blocks) (int, []interface{}, []*ty
 			for !bc.HasState(parent.Root()) {
 				winner = append(winner, parent)
 				parent = bc.GetBlock(parent.ParentHash(), parent.NumberU64()-1)
+				if bc.isBadHash(parent.Hash()) {
+					log.Info("Found bad hash in competing sidechain, aborting import", "hash", parent.Hash(), "number", parent.Number())
+					return i, events, coalescedLogs, ErrBlacklistedHash
+				}
 			}
 			for j := 0; j < len(winner)/2; j++ {
 				winner[j], winner[len(winner)-1-j] = winner[len(winner)-1-j], winner[j]
 			}
 			// Import all the pruned blocks to make the state available
 			bc.chainmu.Unlock()
+			log.Info("Importing competing sidechain", "len", len(winner), "from", winner[0].Number(), "to", winner[len(winner)-1].Number())
 			_, evs, logs, err := bc.insertChain(winner)
 			bc.chainmu.Lock()
 			events, coalescedLogs = evs, logs
@@ -1442,6 +1447,9 @@ func (bc *BlockChain) BadBlocks() []*types.Block {
 	}
 	return blocks
 }
+func (bc *BlockChain) isBadHash(hash common.Hash) bool {
+	return bc.badBlocks.Contains(hash)
+}
 
 // addBadBlock adds a bad block to the bad-block LRU cache
 func (bc *BlockChain) addBadBlock(block *types.Block) {
diff --git a/eth/downloader/downloader.go b/eth/downloader/downloader.go
index 9cfc8a978d..606c1bc81e 100644
--- a/eth/downloader/downloader.go
+++ b/eth/downloader/downloader.go
@@ -1400,7 +1400,7 @@ func (d *Downloader) importBlockResults(results []*fetchResult) error {
 		blocks[i] = types.NewBlockWithHeader(result.Header).WithBody(result.Transactions, result.Uncles)
 	}
 	if index, err := d.blockchain.InsertChain(blocks); err != nil {
-		log.Debug("Downloaded item processing failed", "number", results[index].Header.Number, "hash", results[index].Header.Hash(), "err", err)
+		log.Debug("Downloaded item processing failed", "number", results[index].Header.Number, "hash", results[index].Header.Hash(), "blocks", len(blocks), "err", err)
 		return errInvalidChain
 	}
 	return nil
@@ -1621,7 +1621,7 @@ func (d *Downloader) qosTuner() {
 		atomic.StoreUint64(&d.rttConfidence, conf)
 
 		// Log the new QoS values and sleep until the next RTT
-		log.Debug("Recalculated downloader QoS values", "rtt", rtt, "confidence", float64(conf)/1000000.0, "ttl", d.requestTTL())
+		//log.Debug("Recalculated downloader QoS values", "rtt", rtt, "confidence", float64(conf)/1000000.0, "ttl", d.requestTTL())
 		select {
 		case <-d.quitCh:
 			return