From bfde1a4305817e76b203c2fd6da4d6a7ca41e5f7 Mon Sep 17 00:00:00 2001
From: Gustav Simonsson <gustav.simonsson@gmail.com>
Date: Mon, 14 Sep 2015 16:56:33 +0200
Subject: [PATCH] core: Add BadHashErr and test for BadHashes handling

---
 core/chain_manager.go      |  2 +-
 core/chain_manager_test.go | 55 +++++++++++++++++++++++++++++++++++++-
 core/error.go              | 11 ++++++++
 3 files changed, 66 insertions(+), 2 deletions(-)

diff --git a/core/chain_manager.go b/core/chain_manager.go
index 0ad4f86f9..383fce70c 100644
--- a/core/chain_manager.go
+++ b/core/chain_manager.go
@@ -642,7 +642,7 @@ func (self *ChainManager) InsertChain(chain types.Blocks) (int, error) {
 		}
 
 		if BadHashes[block.Hash()] {
-			err := fmt.Errorf("Found known bad hash in chain %x", block.Hash())
+			err := BadHashError(block.Hash())
 			blockErr(block, err)
 			return i, err
 		}
diff --git a/core/chain_manager_test.go b/core/chain_manager_test.go
index 0c77fc138..6cfafb8c0 100644
--- a/core/chain_manager_test.go
+++ b/core/chain_manager_test.go
@@ -75,7 +75,7 @@ func testFork(t *testing.T, bman *BlockProcessor, i, N int, f func(td1, td2 *big
 	if err != nil {
 		t.Fatal("could not make new canonical in testFork", err)
 	}
-	// asert the bmans have the same block at i
+	// assert the bmans have the same block at i
 	bi1 := bman.bc.GetBlockByNumber(uint64(i)).Hash()
 	bi2 := bman2.bc.GetBlockByNumber(uint64(i)).Hash()
 	if bi1 != bi2 {
@@ -421,6 +421,59 @@ func TestReorgLongest(t *testing.T) {
 	}
 }
 
+func TestBadHashes(t *testing.T) {
+	db, _ := ethdb.NewMemDatabase()
+	genesis, err := WriteTestNetGenesisBlock(db, 0)
+	if err != nil {
+		t.Error(err)
+		t.FailNow()
+	}
+	bc := chm(genesis, db)
+
+	chain := makeChainWithDiff(genesis, []int{1, 2, 4}, 10)
+	BadHashes[chain[2].Header().Hash()] = true
+
+	_, err = bc.InsertChain(chain)
+	if !IsBadHashError(err) {
+		t.Errorf("error mismatch: want: BadHashError, have: %v", err)
+	}
+}
+
+func TestReorgBadHashes(t *testing.T) {
+	db, _ := ethdb.NewMemDatabase()
+	genesis, err := WriteTestNetGenesisBlock(db, 0)
+	if err != nil {
+		t.Error(err)
+		t.FailNow()
+	}
+	bc := chm(genesis, db)
+
+	chain := makeChainWithDiff(genesis, []int{1, 2, 3, 4}, 11)
+	bc.InsertChain(chain)
+
+	if chain[3].Header().Hash() != bc.LastBlockHash() {
+		t.Errorf("last block hash mismatch: want: %x, have: %x", chain[3].Header().Hash(), bc.LastBlockHash())
+	}
+
+	// NewChainManager should check BadHashes when loading it db
+	BadHashes[chain[3].Header().Hash()] = true
+
+	var eventMux event.TypeMux
+	ncm, err := NewChainManager(db, FakePow{}, &eventMux)
+	if err != nil {
+		t.Errorf("NewChainManager err: %s", err)
+	}
+
+	// check it set head to (valid) parent of bad hash block
+	if chain[2].Header().Hash() != ncm.LastBlockHash() {
+		t.Errorf("last block hash mismatch: want: %x, have: %x", chain[2].Header().Hash(), ncm.LastBlockHash())
+	}
+
+	if chain[2].Header().GasLimit.Cmp(ncm.GasLimit()) != 0 {
+		t.Errorf("current block gasLimit mismatch: want: %x, have: %x", chain[2].Header().GasLimit, ncm.GasLimit())
+	}
+}
+
 func TestReorgShortest(t *testing.T) {
 	db, _ := ethdb.NewMemDatabase()
 	genesis, err := WriteTestNetGenesisBlock(db, 0)
diff --git a/core/error.go b/core/error.go
index 09eea22d6..ff58d69d6 100644
--- a/core/error.go
+++ b/core/error.go
@@ -177,3 +177,14 @@ func IsValueTransferErr(e error) bool {
 	_, ok := e.(*ValueTransferError)
 	return ok
 }
+
+type BadHashError common.Hash
+
+func (h BadHashError) Error() string {
+	return fmt.Sprintf("Found known bad hash in chain %x", h)
+}
+
+func IsBadHashError(err error) bool {
+	_, ok := err.(BadHashError)
+	return ok
+}