mointor: implement double sign monitor (bnb-chain#1199)

cmd/geth/main.go

@@ -171,6 +171,7 @@ var (
 		configFileFlag,
 		utils.BlockAmountReserved,
 		utils.CheckSnapshotWithMPT,
+		utils.EnableDoubleSignMonitorFlag,
 	}
 
 	rpcFlags = []cli.Flag{

cmd/utils/flags.go

@@ -902,6 +902,11 @@ var (
 		Name:  "check-snapshot-with-mpt",
 		Usage: "Enable checking between snapshot and MPT ",
 	}
+
+	EnableDoubleSignMonitorFlag = cli.BoolFlag{
+		Name:  "monitor.doublesign",
+		Usage: "Enable double sign monitor to check whether any validator signs multiple blocks",
+	}
 )
 
 // MakeDataDir retrieves the currently requested data directory, terminating
@@ -1168,6 +1173,14 @@ func setLes(ctx *cli.Context, cfg *ethconfig.Config) {
 	}
 }
 
+// setMonitor creates the monitor from the set
+// command line flags, returning empty if the monitor is disabled.
+func setMonitor(ctx *cli.Context, cfg *node.Config) {
+	if ctx.GlobalBool(EnableDoubleSignMonitorFlag.Name) {
+		cfg.EnableDoubleSignMonitor = true
+	}
+}
+
 // MakeDatabaseHandles raises out the number of allowed file handles per process
 // for Geth and returns half of the allowance to assign to the database.
 func MakeDatabaseHandles() int {
@@ -1330,6 +1343,7 @@ func SetNodeConfig(ctx *cli.Context, cfg *node.Config) {
 	setNodeUserIdent(ctx, cfg)
 	setDataDir(ctx, cfg)
 	setSmartCard(ctx, cfg)
+	setMonitor(ctx, cfg)
 
 	if ctx.GlobalIsSet(ExternalSignerFlag.Name) {
 		cfg.ExternalSigner = ctx.GlobalString(ExternalSignerFlag.Name)

core/blockchain.go

@@ -34,6 +34,7 @@ import (
 	"github.com/ethereum/go-ethereum/common/mclock"
 	"github.com/ethereum/go-ethereum/common/prque"
 	"github.com/ethereum/go-ethereum/consensus"
+	"github.com/ethereum/go-ethereum/core/monitor"
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/state/snapshot"
@@ -258,6 +259,9 @@ type BlockChain struct {
 
 	shouldPreserve  func(*types.Block) bool        // Function used to determine whether should preserve the given block.
 	terminateInsert func(common.Hash, uint64) bool // Testing hook used to terminate ancient receipt chain insertion.
+
+	// monitor
+	doubleSignMonitor *monitor.DoubleSignMonitor
 }
 
 // NewBlockChain returns a fully initialised block chain using information
@@ -504,6 +508,13 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, chainConfig *par
 		bc.wg.Add(1)
 		go bc.rewindInvalidHeaderBlockLoop()
 	}
+
+	if bc.doubleSignMonitor != nil {
+		bc.wg.Add(1)
+		go bc.startDoubleSignMonitor()
+
+	}
+
 	return bc, nil
 }
 
@@ -2569,6 +2580,27 @@ func (bc *BlockChain) trustedDiffLayerLoop() {
 	}
 }
 
+func (bc *BlockChain) startDoubleSignMonitor() {
+	eventChan := make(chan ChainHeadEvent, monitor.MaxCacheHeader)
+	sub := bc.SubscribeChainHeadEvent(eventChan)
+	defer func() {
+		sub.Unsubscribe()
+		close(eventChan)
+		bc.wg.Done()
+	}()
+
+	for {
+		select {
+		case event := <-eventChan:
+			if bc.doubleSignMonitor != nil {
+				bc.doubleSignMonitor.Verify(event.Block.Header())
+			}
+		case <-bc.quit:
+			return
+		}
+	}
+}
+
 func (bc *BlockChain) GetUnTrustedDiffLayer(blockHash common.Hash, pid string) *types.DiffLayer {
 	bc.diffMux.RLock()
 	defer bc.diffMux.RUnlock()
@@ -2975,6 +3007,11 @@ func EnableBlockValidator(chainConfig *params.ChainConfig, engine consensus.Engi
 	}
 }
 
+func EnableDoubleSignChecker(bc *BlockChain) (*BlockChain, error) {
+	bc.doubleSignMonitor = monitor.NewDoubleSignMonitor()
+	return bc, nil
+}
+
 func (bc *BlockChain) GetVerifyResult(blockNumber uint64, blockHash common.Hash, diffHash common.Hash) *VerifyResult {
 	var res VerifyResult
 	res.BlockNumber = blockNumber

core/monitor/double_sign_mointor.go

@@ -0,0 +1,103 @@
+package monitor
+
+import (
+	"bytes"
+
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/common/prque"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/rlp"
+)
+
+const (
+	MaxCacheHeader = 100
+)
+
+func NewDoubleSignMonitor() *DoubleSignMonitor {
+	return &DoubleSignMonitor{
+		headerNumbers: prque.New(nil),
+		headers:       make(map[uint64]*types.Header, MaxCacheHeader),
+	}
+}
+
+type DoubleSignMonitor struct {
+	headerNumbers *prque.Prque
+	headers       map[uint64]*types.Header
+}
+
+func (m *DoubleSignMonitor) isDoubleSignHeaders(h1, h2 *types.Header) (bool, error) {
+	if h1 == nil || h2 == nil {
+		return false, nil
+	}
+	if h1.Number.Cmp(h2.Number) != 0 {
+		return false, nil
+	}
+	if !bytes.Equal(h1.ParentHash[:], h2.ParentHash[:]) {
+		return false, nil
+	}
+	// if the Hash is different the signature should not be equal
+	hash1, hash2 := h1.Hash(), h2.Hash()
+	if bytes.Equal(hash1[:], hash2[:]) {
+		return false, nil
+	}
+	// signer is already verified in sync program, we can trust coinbase.
+	if !bytes.Equal(h1.Coinbase[:], h2.Coinbase[:]) {
+		return false, nil
+	}
+
+	return true, nil
+}
+
+func (m *DoubleSignMonitor) deleteOldHeader() {
+	v, _ := m.headerNumbers.Pop()
+	h := v.(*types.Header)
+	delete(m.headers, h.Number.Uint64())
+}
+
+func (m *DoubleSignMonitor) checkHeader(h *types.Header) (bool, *types.Header, error) {
+	h2, exist := m.headers[h.Number.Uint64()]
+	if !exist {
+		if m.headerNumbers.Size() > MaxCacheHeader {
+			m.deleteOldHeader()
+		}
+		m.headers[h.Number.Uint64()] = h
+		m.headerNumbers.Push(h, -h.Number.Int64())
+		return false, nil, nil
+	}
+
+	isDoubleSign, err := m.isDoubleSignHeaders(h, h2)
+	if err != nil {
+		return false, nil, err
+	}
+	if isDoubleSign {
+		return true, h2, nil
+	}
+
+	return false, nil, nil
+}
+
+func (m *DoubleSignMonitor) Verify(h *types.Header) {
+	isDoubleSign, h2, err := m.checkHeader(h)
+	if err != nil {
+		log.Error("check double sign header error", "err", err)
+		return
+	}
+	if isDoubleSign {
+		// found a double sign header
+		log.Warn("found a double sign header", "number", h.Number.Uint64(),
+			"first_hash", h.Hash(), "first_miner", h.Coinbase,
+			"second_hash", h2.Hash(), "second_miner", h2.Coinbase)
+		h1Bytes, err := rlp.EncodeToBytes(h)
+		if err != nil {
+			log.Error("encode header error", "err", err, "hash", h.Hash())
+		}
+		h2Bytes, err := rlp.EncodeToBytes(h2)
+		if err != nil {
+			log.Error("encode header error", "err", err, "hash", h.Hash())
+		}
+		log.Warn("double sign header content",
+			"header1", hexutil.Encode(h1Bytes),
+			"header2", hexutil.Encode(h2Bytes))
+	}
+}

eth/backend.go

@@ -221,6 +221,9 @@ func New(stack *node.Node, config *ethconfig.Config) (*Ethereum, error) {
 	if config.PersistDiff {
 		bcOps = append(bcOps, core.EnablePersistDiff(config.DiffBlock))
 	}
+	if stack.Config().EnableDoubleSignMonitor {
+		bcOps = append(bcOps, core.EnableDoubleSignChecker)
+	}
 
 	peers := newPeerSet()
 	bcOps = append(bcOps, core.EnableBlockValidator(chainConfig, eth.engine, config.TriesVerifyMode, peers))

node/config.go

@@ -201,6 +201,9 @@ type Config struct {
 
 	// AllowUnprotectedTxs allows non EIP-155 protected transactions to be send over RPC.
 	AllowUnprotectedTxs bool `toml:",omitempty"`
+
+	// EnableDoubleSignMonitor is a flag that whether to enable the double signature checker
+	EnableDoubleSignMonitor bool `toml:",omitempty"`
 }
 
 // IPCEndpoint resolves an IPC endpoint based on a configured value, taking into