les: update/recover stable checkpoint

contracts/registrar/contract/registrar.sol

@@ -209,6 +209,6 @@ contract Registrar {
     // The number of confirmations needed before a checkpoint can be registered.
     // We have to make sure the checkpoint registered will not be invalid due to
     // chain reorg.
-    uint constant confirmations = 500;
+    uint constant confirmations = 256;
 }
 

contracts/registrar/registrar.go

@@ -32,19 +32,14 @@ import (
 var (
 	// registrar contract address for mainnet and testnet.
 	RegistrarAddr = map[common.Hash]common.Address{
-		params.MainnetGenesisHash: common.HexToAddress(""),
-		params.TestnetGenesisHash: common.HexToAddress(""),
+		// params.MainnetGenesisHash: common.HexToAddress(""),
+		// params.TestnetGenesisHash: common.HexToAddress(""),
 		params.RinkebyGenesisHash: common.HexToAddress("0xe3f2686a5d0c56a2d853c19c46b173a755263be8"),
 	}
 )
 
 var errEventNotFound = errors.New("contract event not found")
 
-const (
-	sectionSize            = 32768 // The frequency for creating a checkpoint
-	checkpointConfirmation = 500   // The number of confirmations needed before a checkpoint can be accepted
-)
-
 type Registrar struct {
 	contract *contract.Contract
 }
@@ -67,15 +62,14 @@ func (registrar *Registrar) WatchNewCheckpointEvent(sink chan<- *contract.Contra
 }
 
 // FilterNewCheckpointEvent filters out NewCheckpointEvent for specific section number.
-func (registrar *Registrar) FilterNewCheckpointEvent(head uint64, section uint64) (*contract.ContractNewCheckpointEventIterator, error) {
-	start := (section + 1) * sectionSize
-	end := head - checkpointConfirmation
-	if end < start {
+func (registrar *Registrar) FilterNewCheckpointEvent(head, section, sectionSize, processConfirm uint64) (*contract.ContractNewCheckpointEventIterator, error) {
+	start := (section+1)*sectionSize + processConfirm
+	if head < start {
 		return nil, errEventNotFound
 	}
 	opt := &bind.FilterOpts{
 		Start: start,
-		End:   &end,
+		End:   &head,
 	}
 	return registrar.contract.FilterNewCheckpointEvent(opt, []*big.Int{big.NewInt(int64(section))})
 }

contracts/registrar/registrar_test.go

@@ -213,9 +213,27 @@ func TestCheckpointRegister(t *testing.T) {
 		return nil
 	}, "register unstable checkpoint")
 
+	contractBackend.ShiftBlocks(light.CheckpointFrequency + light.CheckpointProcessConfirmations)
+
+	// Register by unauthorized user
+	validateOperation(t, c, contractBackend, func() {
+		user2, _ := crypto.GenerateKey()
+		unauthorized := bind.NewKeyedTransactor(user2)
+		c.SetCheckpoint(unauthorized, big.NewInt(int64(trustedCheckpoint.SectionIdx)), trustedCheckpoint.SectionHead,
+			trustedCheckpoint.ChtRoot, trustedCheckpoint.BloomTrieRoot)
+	}, func(events <-chan *contract.ContractNewCheckpointEvent, events2 <-chan *contract.ContractAddAdminEvent, events3 <-chan *contract.ContractRemoveAdminEvent) error {
+		hash, err := c.GetCheckpoint(nil, big.NewInt(int64(trustedCheckpoint.SectionIdx)))
+		if err != nil {
+			return errors.New("get checkpoint failed")
+		}
+		if hash != emptyHash {
+			return errors.New("unstable checkpoint should be banned")
+		}
+		return nil
+	}, "register by unauthorized user")
+
 	// Register a stable checkpoint
 	validateOperation(t, c, contractBackend, func() {
-		contractBackend.ShiftBlocks(sectionSize + checkpointConfirmation)
 		c.SetCheckpoint(transactOpts, big.NewInt(int64(trustedCheckpoint.SectionIdx)), trustedCheckpoint.SectionHead,
 			trustedCheckpoint.ChtRoot, trustedCheckpoint.BloomTrieRoot)
 	}, func(events <-chan *contract.ContractNewCheckpointEvent, events2 <-chan *contract.ContractAddAdminEvent, events3 <-chan *contract.ContractRemoveAdminEvent) error {
@@ -223,7 +241,7 @@ func TestCheckpointRegister(t *testing.T) {
 		if err != nil {
 			return errors.New("get checkpoint failed")
 		}
-		if common.Hash(hash).Hex() != crypto.Keccak256Hash(trustedCheckpoint.SectionHead.Bytes(), trustedCheckpoint.ChtRoot.Bytes(), trustedCheckpoint.BloomTrieRoot.Bytes()).Hex() {
+		if !trustedCheckpoint.HashEqual(common.Hash(hash)) {
 			return errors.New("register stable checkpoint failed")
 		}
 		if !validateEvents(1, events) {
@@ -242,7 +260,7 @@ func TestCheckpointRegister(t *testing.T) {
 		if err != nil {
 			return errors.New("get checkpoint failed")
 		}
-		if common.Hash(hash).Hex() != crypto.Keccak256Hash(trustedCheckpoint.SectionHead.Bytes(), trustedCheckpoint.ChtRoot.Bytes(), trustedCheckpoint.BloomTrieRoot.Bytes()).Hex() {
+		if !trustedCheckpoint.HashEqual(common.Hash(hash)) {
 			return errors.New("register stable checkpoint failed")
 		}
 		if !validateEvents(1, events) {

les/server.go

@@ -19,6 +19,7 @@ package les
 
 import (
 	"crypto/ecdsa"
+	"errors"
 	"sync"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -28,6 +29,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/eth"
+	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/les/flowcontrol"
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/log"
@@ -36,8 +38,13 @@ import (
 	"github.com/ethereum/go-ethereum/rpc"
 )
 
+// chainHeadChanSize is the size of channel listening to ChainHeadEvent.
+const SubscribeChainHeadEvent = 10
+
 type LesServer struct {
 	config          *eth.Config
+	backend         *eth.EthAPIBackend
+	chaindb         ethdb.Database
 	protocolManager *ProtocolManager
 	fcManager       *flowcontrol.ClientManager // nil if our node is client only
 	fcCostStats     *requestCostStats
@@ -69,6 +76,8 @@ func NewLesServer(eth *eth.Ethereum, config *eth.Config) (*LesServer, error) {
 
 	srv := &LesServer{
 		config:           config,
+		backend:          eth.APIBackend,
+		chaindb:          eth.ChainDb(),
 		protocolManager:  pm,
 		quitSync:         quitSync,
 		lesTopics:        lesTopics,
@@ -85,14 +94,14 @@ func NewLesServer(eth *eth.Ethereum, config *eth.Config) (*LesServer, error) {
 		// convert last LES/2 section index back to LES/1 index for chtIndexer.SectionHead
 		chtLastSectionV1 := (chtLastSection+1)*(light.CHTFrequencyClient/light.CHTFrequencyServer) - 1
 		chtSectionHead := srv.chtIndexer.SectionHead(chtLastSectionV1)
-		chtRoot := light.GetChtV2Root(pm.chainDb, chtLastSection, chtSectionHead)
+		chtRoot := light.GetChtV2Root(srv.chaindb, chtLastSection, chtSectionHead)
 		logger.Info("Loaded CHT", "section", chtLastSection, "head", chtSectionHead, "root", chtRoot)
 	}
 	bloomTrieSectionCount, _, _ := srv.bloomTrieIndexer.Sections()
 	if bloomTrieSectionCount != 0 {
 		bloomTrieLastSection := bloomTrieSectionCount - 1
 		bloomTrieSectionHead := srv.bloomTrieIndexer.SectionHead(bloomTrieLastSection)
-		bloomTrieRoot := light.GetBloomTrieRoot(pm.chainDb, bloomTrieLastSection, bloomTrieSectionHead)
+		bloomTrieRoot := light.GetBloomTrieRoot(srv.chaindb, bloomTrieLastSection, bloomTrieSectionHead)
 		logger.Info("Loaded bloom trie", "section", bloomTrieLastSection, "head", bloomTrieSectionHead, "root", bloomTrieRoot)
 	}
 
@@ -137,6 +146,7 @@ func (s *LesServer) Start(srvr *p2p.Server) {
 	s.privateKey = srvr.PrivateKey
 	s.protocolManager.blockLoop()
 	if s.registrar != nil {
+		s.stableCheckpoint = s.recoverCheckpoint()
 		go s.checkpointLoop()
 	}
 }
@@ -204,29 +214,66 @@ func (s *LesServer) getCheckpoint(index uint64) (common.Hash, common.Hash, commo
 	return sectionHead, chtRoot, bloomTrieRoot
 }
 
-// checkpointLoop starts a standalone goroutine to watch new checkpoint event and updates local's stable checkpoint.
+// checkpointLoop starts a standalone goroutine to watch new checkpoint events and updates local's stable checkpoint.
 func (s *LesServer) checkpointLoop() (err error) {
-	sink := make(chan *contract.ContractNewCheckpointEvent)
-	sub, err := s.registrar.WatchNewCheckpointEvent(sink)
+	var (
+		eventCh      = make(chan *contract.ContractNewCheckpointEvent)
+		headCh       = make(chan core.ChainHeadEvent, SubscribeChainHeadEvent)
+		announcement = make(map[uint64]common.Hash)
+	)
+	eventSub, err := s.registrar.WatchNewCheckpointEvent(eventCh)
 	if err != nil {
-		return
-
+		return err
+	}
+	headSub := s.backend.SubscribeChainHeadEvent(headCh)
+	if headSub == nil {
+		eventSub.Unsubscribe()
+		return errors.New("subscribe head event failed")
 	}
 	defer func() {
-		sub.Unsubscribe()
+		eventSub.Unsubscribe()
+		headSub.Unsubscribe()
 	}()
 
 	for {
 		select {
-		case event := <-sink:
-			// Note several duplicate events can be received because of latest checkpoint modification is allowed.
-			// Always update local checkpoint when the section index is not less than the local one.
-			// todo(rjl493456442) update local checkpoint
-			if event.Index.Uint64() >= s.stableCheckpoint.SectionIdx {
-				log.Info("update checkpoint", "section", event.Index, "hash", common.Hash(event.CheckpointHash).Hex(),
-					"grantor", event.Grantor.Hex())
+		case event := <-eventCh:
+			if event == nil {
+				// This should never happen.
+				log.Info("Ignore empty checkpoint event")
+				continue
+			}
+			// Note several duplicate events may be received because of chain reorg and the modification of the latest checkpoint.
+			if s.stableCheckpoint == nil || event.Index.Uint64() >= s.stableCheckpoint.SectionIdx {
+				log.Info("Receive new checkpoint event", "section", event.Index, "hash", common.Hash(event.CheckpointHash).Hex(),
+					"grantor", event.Grantor.Hex())
+				announcement[event.Index.Uint64()] = common.Hash(event.CheckpointHash)
+			}
+		case head := <-headCh:
+			number := head.Block.NumberU64()
+			if number < light.CheckpointConfirmations+light.CheckpointFrequency {
+				continue
+			}
+			idx := (number-light.CheckpointConfirmations)/light.CheckpointFrequency - 1
+			if s.stableCheckpoint == nil || idx > s.stableCheckpoint.SectionIdx {
+				hash, ok := announcement[idx]
+				if !ok {
+					continue
+				}
+				sectionHead := s.bloomTrieIndexer.SectionHead(idx)
+				checkpoint := &light.TrustedCheckpoint{
+					SectionIdx:    idx,
+					SectionHead:   sectionHead,
+					ChtRoot:       light.GetChtV2Root(s.chaindb, idx, sectionHead),
+					BloomTrieRoot: light.GetBloomTrieRoot(s.chaindb, idx, sectionHead),
+				}
+				if checkpoint.HashEqual(common.Hash(hash)) {
+					light.WriteTrustedCheckpoint(s.chaindb, checkpoint)
+					s.stableCheckpoint = checkpoint
+					log.Info("Update stable checkpoint", "section", checkpoint.SectionIdx)
+					delete(announcement, idx)
+				}
 			}
-
 		case <-s.quitSync:
 			// Les server is closed.
 			return
@@ -234,6 +281,53 @@ func (s *LesServer) checkpointLoop() (err error) {
 	}
 }
 
+// recoveryCheckpoint filters checkpoint announcement events and recovers stable checkpoint.
+func (s *LesServer) recoverCheckpoint() *light.TrustedCheckpoint {
+	var (
+		sectionCnt, _, _ = s.bloomTrieIndexer.Sections()
+		stable           = light.ReadTrustedCheckpoint(s.chaindb)
+		unstableIdx      = sectionCnt - 1
+		headHash         = rawdb.ReadHeadHeaderHash(s.chaindb)
+		headNumber       = rawdb.ReadHeaderNumber(s.chaindb, headHash)
+	)
+	if headNumber == nil {
+		return nil
+	}
+	for stable == nil || stable.SectionIdx < unstableIdx {
+		if (unstableIdx+1)*light.CheckpointFrequency+light.CheckpointConfirmations <= *headNumber {
+			iter, err := s.registrar.FilterNewCheckpointEvent(*headNumber, unstableIdx, light.CheckpointFrequency, light.CheckpointProcessConfirmations)
+			if err == nil {
+				for iter.Next() {
+					sectionHead := s.bloomTrieIndexer.SectionHead(unstableIdx)
+					checkpoint := &light.TrustedCheckpoint{
+						SectionIdx:    unstableIdx,
+						SectionHead:   sectionHead,
+						ChtRoot:       light.GetChtV2Root(s.chaindb, unstableIdx, sectionHead),
+						BloomTrieRoot: light.GetBloomTrieRoot(s.chaindb, unstableIdx, sectionHead),
+					}
+					if checkpoint.HashEqual(common.Hash(iter.Event.CheckpointHash)) {
+						light.WriteTrustedCheckpoint(s.chaindb, checkpoint)
+						iter.Close()
+						log.Info("Recover checkpoint", "index", checkpoint.SectionIdx)
+						return checkpoint
+					}
+				}
+				iter.Close()
+			}
+		}
+		if unstableIdx == 0 {
+			break
+		}
+		unstableIdx -= 1
+	}
+	if stable == nil {
+		log.Info("No stable checkpoint")
+	} else {
+		log.Info("Recover checkpoint", "index", stable.SectionIdx)
+	}
+	return stable
+}
+
 func (pm *ProtocolManager) blockLoop() {
 	pm.wg.Add(1)
 	headCh := make(chan core.ChainHeadEvent, 10)

light/checkpoint.go

@@ -20,17 +20,27 @@ import (
 	"io"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
-var (
-	// checkpointKey tracks the latest stable checkpoint.
-	checkpointKey = []byte("Checkpoint")
+const (
+	// CheckpointFrequency is the block frequency for creating checkpoint
+	CheckpointFrequency = 32768
+
+	// CheckpointProcessConfirmations is the number before a checkpoint is generated
+	CheckpointProcessConfirmations = 256
+
+	// CheckpointConfirmations is the number of confirmations before a checkpoint is stable
+	CheckpointConfirmations = 8192
 )
 
+// checkpointKey tracks the latest stable checkpoint.
+var checkpointKey = []byte("Checkpoint")
+
 // TrustedCheckpoint represents a set of post-processed trie roots (CHT and BloomTrie) associated with
 // the appropriate section index and head hash.
 //
@@ -68,6 +78,15 @@ func (c *TrustedCheckpoint) DecodeRLP(s *rlp.Stream) error {
 	return nil
 }
 
+// HashEqual returns an indicator comparing the itself hash with given one.
+// A nil argument is equivalent to an empty slice.
+func (c *TrustedCheckpoint) HashEqual(hash common.Hash) bool {
+	if c.SectionHead == (common.Hash{}) && c.ChtRoot == (common.Hash{}) && c.BloomTrieRoot == (common.Hash{}) {
+		return hash == common.Hash{}
+	}
+	return crypto.Keccak256Hash(c.SectionHead.Bytes(), c.ChtRoot.Bytes(), c.BloomTrieRoot.Bytes()) == hash
+}
+
 var (
 	// Hardcode checkpoint for mainnet and testnet(ropsten). Will be deleted eventually once checkpoint contract
 	// works.

light/checkpoint_test.go

@@ -39,6 +39,16 @@ func TestRWCheckpoint(t *testing.T) {
 	}
 }
 
+func TestHashEqual(t *testing.T) {
+	if !testCheckpoint.HashEqual(common.HexToHash("0x6142a271d44a56107cd9de0be0a04211841593906b310f8c4d33be56b6e78959")) {
+		t.Error("checkpoint should hash equal to given one")
+	}
+	emptyCheckpoint := &TrustedCheckpoint{}
+	if !emptyCheckpoint.HashEqual(common.Hash{}) {
+		t.Error("empty checkpoint should equal to empty hash")
+	}
+}
+
 func assertCheckpointEqual(ckp1, ckp2 *TrustedCheckpoint) bool {
 	return ckp1.SectionIdx == ckp2.SectionIdx && ckp1.SectionHead == ckp2.SectionHead && ckp1.ChtRoot == ckp2.ChtRoot &&
 		ckp1.BloomTrieRoot == ckp2.BloomTrieRoot