core: fix import errors on clique crashes + empty blocks (#19544)

* core: fix import errors on clique crashes + empty blocks

* cosensus/clique, core: add test for the mirrored state issue

* core: address todo question wrt log count

* core: raise a louder warning for non-clique known blocks

1 files changed, 113 insertions, 0 deletions

diff --git a/consensus/clique/clique_test.go b/consensus/clique/clique_test.go
new file mode 100644
index 000000000..710f44805
--- /dev/null
+++ b/consensus/clique/clique_test.go
@@ -0,0 +1,113 @@
+// Copyright 2019 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package clique
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/rawdb"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+// This test case is a repro of an annoying bug that took us forever to catch.
+// In Clique PoA networks (Rinkeby, Görli, etc), consecutive blocks might have
+// the same state root (no block subsidy, empty block). If a node crashes, the
+// chain ends up losing the recent state and needs to regenerate it from blocks
+// already in the database. The bug was that processing the block *prior* to an
+// empty one **also completes** the empty one, ending up in a known-block error.
+func TestReimportMirroredState(t *testing.T) {
+	// Initialize a Clique chain with a single signer
+	var (
+		db     = rawdb.NewMemoryDatabase()
+		key, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
+		addr   = crypto.PubkeyToAddress(key.PublicKey)
+		engine = New(params.AllCliqueProtocolChanges.Clique, db)
+		signer = new(types.HomesteadSigner)
+	)
+	genspec := &core.Genesis{
+		ExtraData: make([]byte, extraVanity+common.AddressLength+extraSeal),
+		Alloc: map[common.Address]core.GenesisAccount{
+			addr: {Balance: big.NewInt(1)},
+		},
+	}
+	copy(genspec.ExtraData[extraVanity:], addr[:])
+	genesis := genspec.MustCommit(db)
+
+	// Generate a batch of blocks, each properly signed
+	chain, _ := core.NewBlockChain(db, nil, params.AllCliqueProtocolChanges, engine, vm.Config{}, nil)
+	defer chain.Stop()
+
+	blocks, _ := core.GenerateChain(params.AllCliqueProtocolChanges, genesis, engine, db, 3, func(i int, block *core.BlockGen) {
+		// The chain maker doesn't have access to a chain, so the difficulty will be
+		// lets unset (nil). Set it here to the correct value.
+		block.SetDifficulty(diffInTurn)
+
+		// We want to simulate an empty middle block, having the same state as the
+		// first one. The last is needs a state change again to force a reorg.
+		if i != 1 {
+			tx, err := types.SignTx(types.NewTransaction(block.TxNonce(addr), common.Address{0x00}, new(big.Int), params.TxGas, nil, nil), signer, key)
+			if err != nil {
+				panic(err)
+			}
+			block.AddTxWithChain(chain, tx)
+		}
+	})
+	for i, block := range blocks {
+		header := block.Header()
+		if i > 0 {
+			header.ParentHash = blocks[i-1].Hash()
+		}
+		header.Extra = make([]byte, extraVanity+extraSeal)
+		header.Difficulty = diffInTurn
+
+		sig, _ := crypto.Sign(SealHash(header).Bytes(), key)
+		copy(header.Extra[len(header.Extra)-extraSeal:], sig)
+		blocks[i] = block.WithSeal(header)
+	}
+	// Insert the first two blocks and make sure the chain is valid
+	db = rawdb.NewMemoryDatabase()
+	genspec.MustCommit(db)
+
+	chain, _ = core.NewBlockChain(db, nil, params.AllCliqueProtocolChanges, engine, vm.Config{}, nil)
+	defer chain.Stop()
+
+	if _, err := chain.InsertChain(blocks[:2]); err != nil {
+		t.Fatalf("failed to insert initial blocks: %v", err)
+	}
+	if head := chain.CurrentBlock().NumberU64(); head != 2 {
+		t.Fatalf("chain head mismatch: have %d, want %d", head, 2)
+	}
+
+	// Simulate a crash by creating a new chain on top of the database, without
+	// flushing the dirty states out. Insert the last block, trigerring a sidechain
+	// reimport.
+	chain, _ = core.NewBlockChain(db, nil, params.AllCliqueProtocolChanges, engine, vm.Config{}, nil)
+	defer chain.Stop()
+
+	if _, err := chain.InsertChain(blocks[2:]); err != nil {
+		t.Fatalf("failed to insert final block: %v", err)
+	}
+	if head := chain.CurrentBlock().NumberU64(); head != 3 {
+		t.Fatalf("chain head mismatch: have %d, want %d", head, 3)
+	}
+}