all: implement simple checkpoint syncing

cmd, les, node: remove callback mechanism

cmd, node: remove callback definition

les: simplify the registrar

les: expose checkpoint rpc services in the light client

les, light: don't store untrusted receipt

cmd, contracts, les: discard stale checkpoint

cmd, contracts/registrar: loose restriction of registeration

cmd, contracts: add replay-protection

all: off-chain multi-signature contract

params: deploy checkpoint contract for rinkeby

cmd/registrar: add raw signing mode for registrar

cmd/registrar, contracts/registrar, les: fixed messages

accounts/abi/bind/backends/simulated.go

@@ -45,8 +45,10 @@ import (
 // This nil assignment ensures compile time that SimulatedBackend implements bind.ContractBackend.
 var _ bind.ContractBackend = (*SimulatedBackend)(nil)
 
-var errBlockNumberUnsupported = errors.New("SimulatedBackend cannot access blocks other than the latest block")
+var (
-var errGasEstimationFailed = errors.New("gas required exceeds allowance or always failing transaction")
+	errBlockNumberUnsupported = errors.New("simulatedBackend cannot access blocks other than the latest block")
+	errGasEstimationFailed    = errors.New("gas required exceeds allowance or always failing transaction")
+)
 
 // SimulatedBackend implements bind.ContractBackend, simulating a blockchain in
 // the background. Its main purpose is to allow easily testing contract bindings.
@@ -65,8 +67,11 @@ type SimulatedBackend struct {
 
 // NewSimulatedBackend creates a new binding backend using a simulated blockchain
 // for testing purposes.
-func NewSimulatedBackend(alloc core.GenesisAlloc, gasLimit uint64) *SimulatedBackend {
+func NewSimulatedBackend(database ethdb.Database, alloc core.GenesisAlloc, gasLimit uint64) *SimulatedBackend {
-	database := rawdb.NewMemoryDatabase()
+	// Don't panic for the lazy user.
+	if database == nil {
+		database = rawdb.NewMemoryDatabase()
+	}
 	genesis := core.Genesis{Config: params.AllEthashProtocolChanges, GasLimit: gasLimit, Alloc: alloc}
 	genesis.MustCommit(database)
 	blockchain, _ := core.NewBlockChain(database, nil, genesis.Config, ethash.NewFaker(), vm.Config{}, nil)
@@ -424,6 +429,33 @@ func (b *SimulatedBackend) AdjustTime(adjustment time.Duration) error {
 	return nil
 }
 
+// InsertEmptyBlocks inserts a batch of empty blocks to blockchain.
+func (b *SimulatedBackend) InsertEmptyBlocks(number int) error {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	// Insert a batch of empty blocks and commit to the database
+	blocks, _ := core.GenerateChain(b.config, b.blockchain.CurrentBlock(), ethash.NewFaker(), b.database, number, func(i int, block *core.BlockGen) {})
+	if _, err := b.blockchain.InsertChain(blocks); err != nil {
+		panic(err) // This cannot happen unless the simulator is wrong, fail in that case
+	}
+	// Apply all pending transactions to new pending blocks.
+	blocks, _ = core.GenerateChain(b.config, b.blockchain.CurrentBlock(), ethash.NewFaker(), b.database, 1, func(number int, block *core.BlockGen) {
+		for _, tx := range b.pendingBlock.Transactions() {
+			block.AddTx(tx)
+		}
+	})
+
+	statedb, _ := b.blockchain.State()
+	b.pendingBlock = blocks[0]
+	b.pendingState, _ = state.New(b.pendingBlock.Root(), statedb.Database())
+	return nil
+}
+
+// Blockchain returns the underlying blockchain.
+func (b *SimulatedBackend) Blockchain() *core.BlockChain {
+	return b.blockchain
+}
+
 // callmsg implements core.Message to allow passing it as a transaction simulator.
 type callmsg struct {
 	ethereum.CallMsg

accounts/abi/bind/backends/simulated_test.go

@@ -37,7 +37,7 @@ func TestSimulatedBackend(t *testing.T) {
 	genAlloc := make(core.GenesisAlloc)
 	genAlloc[auth.From] = core.GenesisAccount{Balance: big.NewInt(9223372036854775807)}
 
-	sim := backends.NewSimulatedBackend(genAlloc, gasLimit)
+	sim := backends.NewSimulatedBackend(nil, genAlloc, gasLimit)
 
 	// should return an error if the tx is not found
 	txHash := common.HexToHash("2")

accounts/abi/bind/bind_test.go

@@ -258,7 +258,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
+			sim := backends.NewSimulatedBackend(nil, core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy an interaction tester contract and call a transaction on it
 			_, _, interactor, err := DeployInteractor(auth, sim, "Deploy string")
@@ -307,7 +307,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
+			sim := backends.NewSimulatedBackend(nil, core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a tuple tester contract and execute a structured call on it
 			_, _, getter, err := DeployGetter(auth, sim)
@@ -347,7 +347,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
+			sim := backends.NewSimulatedBackend(nil, core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a tuple tester contract and execute a structured call on it
 			_, _, tupler, err := DeployTupler(auth, sim)
@@ -399,7 +399,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
+			sim := backends.NewSimulatedBackend(nil, core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a slice tester contract and execute a n array call on it
 			_, _, slicer, err := DeploySlicer(auth, sim)
@@ -441,7 +441,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
+			sim := backends.NewSimulatedBackend(nil, core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a default method invoker contract and execute its default method
 			_, _, defaulter, err := DeployDefaulter(auth, sim)
@@ -475,11 +475,12 @@ var bindTests = []struct {
 		`
 			"github.com/ethereum/go-ethereum/accounts/abi/bind"
 			"github.com/ethereum/go-ethereum/accounts/abi/bind/backends"
+			"github.com/ethereum/go-ethereum/core"
 			"github.com/ethereum/go-ethereum/common"
 		`,
 		`
 			// Create a simulator and wrap a non-deployed contract
-			sim := backends.NewSimulatedBackend(nil, uint64(10000000000))
+			sim := backends.NewSimulatedBackend(nil, core.GenesisAlloc{}, uint64(10000000000))
 
 			nonexistent, err := NewNonExistent(common.Address{}, sim)
 			if err != nil {
@@ -523,7 +524,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
+			sim := backends.NewSimulatedBackend(nil, core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a funky gas pattern contract
 			_, _, limiter, err := DeployFunkyGasPattern(auth, sim)
@@ -567,7 +568,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
+			sim := backends.NewSimulatedBackend(nil, core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a sender tester contract and execute a structured call on it
 			_, _, callfrom, err := DeployCallFrom(auth, sim)
@@ -636,7 +637,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
+			sim := backends.NewSimulatedBackend(nil, core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy a underscorer tester contract and execute a structured call on it
 			_, _, underscorer, err := DeployUnderscorer(auth, sim)
@@ -724,7 +725,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
+			sim := backends.NewSimulatedBackend(nil, core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			// Deploy an eventer contract
 			_, _, eventer, err := DeployEventer(auth, sim)
@@ -908,7 +909,7 @@ var bindTests = []struct {
 			// Generate a new random account and a funded simulator
 			key, _ := crypto.GenerateKey()
 			auth := bind.NewKeyedTransactor(key)
-			sim := backends.NewSimulatedBackend(core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
+			sim := backends.NewSimulatedBackend(nil, core.GenesisAlloc{auth.From: {Balance: big.NewInt(10000000000)}}, 10000000)
 
 			//deploy the test contract
 			_, _, testContract, err := DeployDeeplyNestedArray(auth, sim)

accounts/abi/bind/template.go

@@ -439,6 +439,18 @@ var (
 				}
 			}), nil
 		}
+
+		// Parse{{.Normalized.Name}} is a log parse operation binding the contract event 0x{{printf "%x" .Original.Id}}.
+		//
+		// Solidity: {{.Original.String}}
+		func (_{{$contract.Type}} *{{$contract.Type}}Filterer) Parse{{.Normalized.Name}}(log types.Log) (*{{$contract.Type}}{{.Normalized.Name}}, error) {
+			event := new({{$contract.Type}}{{.Normalized.Name}})
+			if err := _{{$contract.Type}}.contract.UnpackLog(event, "{{.Original.Name}}", log); err != nil {
+				return nil, err
+			}
+			return event, nil	
+		}
+
  	{{end}}
 {{end}}
 `

accounts/abi/bind/util_test.go

@@ -54,9 +54,11 @@ var waitDeployedTests = map[string]struct {
 func TestWaitDeployed(t *testing.T) {
 	for name, test := range waitDeployedTests {
 		backend := backends.NewSimulatedBackend(
+			nil,
 			core.GenesisAlloc{
 				crypto.PubkeyToAddress(testKey.PublicKey): {Balance: big.NewInt(10000000000)},
-			}, 10000000,
+			},
+			10000000,
 		)
 
 		// Create the transaction.

cmd/geth/main.go

@@ -37,6 +37,7 @@ import (
 	"github.com/ethereum/go-ethereum/eth/downloader"
 	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/ethereum/go-ethereum/internal/debug"
+	"github.com/ethereum/go-ethereum/les"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/node"
@@ -321,14 +322,33 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 	events := make(chan accounts.WalletEvent, 16)
 	stack.AccountManager().Subscribe(events)
 
-	go func() {
+	// Create a client to interact with local geth node.
-		// Create a chain state reader for self-derivation
 	rpcClient, err := stack.Attach()
 	if err != nil {
 		utils.Fatalf("Failed to attach to self: %v", err)
 	}
-		stateReader := ethclient.NewClient(rpcClient)
+	ethClient := ethclient.NewClient(rpcClient)
 
+	// Set contract backend for ethereum service if local node
+	// is serving LES requests.
+	if ctx.GlobalInt(utils.LightServFlag.Name) > 0 {
+		var ethService *eth.Ethereum
+		if err := stack.Service(&ethService); err != nil {
+			utils.Fatalf("Failed to retrieve ethereum service: %v", err)
+		}
+		ethService.SetContractBackend(ethClient)
+	}
+	// Set contract backend for les service if local node is
+	// running as a light client.
+	if ctx.GlobalString(utils.SyncModeFlag.Name) == "light" {
+		var lesService *les.LightEthereum
+		if err := stack.Service(&lesService); err != nil {
+			utils.Fatalf("Failed to retrieve light ethereum service: %v", err)
+		}
+		lesService.SetContractBackend(ethClient)
+	}
+
+	go func() {
 		// Open any wallets already attached
 		for _, wallet := range stack.AccountManager().Wallets() {
 			if err := wallet.Open(""); err != nil {
@@ -352,7 +372,7 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 				}
 				derivationPaths = append(derivationPaths, accounts.DefaultBaseDerivationPath)
 
-				event.Wallet.SelfDerive(derivationPaths, stateReader)
+				event.Wallet.SelfDerive(derivationPaths, ethClient)
 
 			case accounts.WalletDropped:
 				log.Info("Old wallet dropped", "url", event.Wallet.URL())
@@ -381,7 +401,6 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 						"age", common.PrettyAge(timestamp))
 					stack.Stop()
 				}
-
 			}
 		}()
 	}

cmd/puppeth/wizard_genesis.go

@@ -27,10 +27,17 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strings"
 	"time"
 
+	"github.com/ethereum/go-ethereum/accounts/abi"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/math"
+	"github.com/ethereum/go-ethereum/contracts/registrar/contract"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/rawdb"
+	"github.com/ethereum/go-ethereum/core/state"
+	"github.com/ethereum/go-ethereum/core/vm/runtime"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
 )
@@ -132,6 +139,64 @@ func (w *wizard) makeGenesis() {
 	fmt.Println("Specify your chain/network ID if you want an explicit one (default = random)")
 	genesis.Config.ChainID = new(big.Int).SetUint64(uint64(w.readDefaultInt(rand.Intn(65536))))
 
+	// Query the user for checkpoint contract config
+	fmt.Println()
+	fmt.Println("Should checkpoint contract be deployed (default = no)")
+	if w.readDefaultYesNo(false) {
+		// Read the address of the trusted signers
+		fmt.Println("Which accounts should be the trusted signer? (advisable at least one)")
+		var (
+			signers   []common.Address
+			threshold *big.Int
+		)
+		// Get trusted signer addresses
+		for {
+			if address := w.readAddress(); address != nil {
+				signers = append(signers, *address)
+				continue
+			}
+			break
+		}
+		// Get stable checkpoint signature minFraction
+		for {
+			fmt.Printf("What is the minimal approval threshold? (maximum %d)\n", len(signers))
+			threshold = w.readDefaultBigInt(big.NewInt(0))
+			if threshold.Int64() <= 0 || threshold.Int64() > int64(len(signers)) {
+				fmt.Printf("Invalid approval threshold, please enter in range [1, %d]\n", len(signers))
+			}
+			break
+		}
+		parsed, err := abi.JSON(strings.NewReader(contract.ContractABI))
+		if err != nil {
+			log.Crit("Parse contract ABI failed", "err", err)
+		}
+		input, err := parsed.Pack("", signers, big.NewInt(params.CheckpointFrequency), big.NewInt(params.CheckpointProcessConfirmations), threshold)
+		if err != nil {
+			log.Crit("Pack contract constructor arguments failed", "err", err)
+		}
+		config := &runtime.Config{GasLimit: math.MaxInt64}
+		config.State, _ = state.New(common.Hash{}, state.NewDatabase(rawdb.NewMemoryDatabase()))
+		code, address, _, err := runtime.Create(append(common.FromHex(contract.ContractBin), input...), config)
+		if err != nil {
+			log.Crit("Execute contract constructor failed", "err", err)
+		}
+		config.State.Commit(true)
+		genesis.Alloc[address] = core.GenesisAccount{Code: code, Storage: make(map[common.Hash]common.Hash), Balance: big.NewInt(1)}
+		err = config.State.ForEachStorage(address, func(key, value common.Hash) bool {
+			genesis.Alloc[address].Storage[key] = value
+			return true
+		})
+		if err != nil {
+			log.Crit("Failed to iterate contract storage", "err", err)
+		}
+		genesis.Config.CheckpointContract = &params.CheckpointContractConfig{
+			Name:         w.network,
+			ContractAddr: address,
+			Signers:      signers,
+			Threshold:    threshold.Uint64(),
+		}
+	}
+
 	// All done, store the genesis and flush to disk
 	log.Info("Configured new genesis block")
 

cmd/registrar/common.go

@@ -0,0 +1,172 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of go-ethereum.
+//
+// go-ethereum is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// go-ethereum 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 General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"io/ioutil"
+	"strconv"
+	"strings"
+
+	"github.com/ethereum/go-ethereum/accounts/keystore"
+	"github.com/ethereum/go-ethereum/cmd/utils"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/console"
+	"github.com/ethereum/go-ethereum/contracts/registrar"
+	"github.com/ethereum/go-ethereum/ethclient"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/rpc"
+	"gopkg.in/urfave/cli.v1"
+)
+
+// newClient creates a client with specified remote URL.
+func newClient(ctx *cli.Context) *ethclient.Client {
+	url := ctx.GlobalString(nodeURLFlag.Name)
+	client, err := ethclient.Dial(url)
+	if err != nil {
+		utils.Fatalf("Failed to setup ethereum client at url %s: %v", url, err)
+	}
+	log.Info("Setup ethereum client", "URL", url)
+	return client
+}
+
+// newRPCClient creates a rpc client with specified node URL.
+func newRPCClient(url string) *rpc.Client {
+	client, err := rpc.Dial(url)
+	if err != nil {
+		utils.Fatalf("Failed to setup rpc client at url %s: %v", url, err)
+	}
+	log.Info("Setup rpc client", "URL", url)
+	return client
+}
+
+// getContractAddr retrieves the register contract address through
+// rpc request.
+func getContractAddr(client *rpc.Client) common.Address {
+	var addr string
+	err := client.Call(&addr, "les_getCheckpointContractAddress")
+	if err != nil {
+		utils.Fatalf("Failed to fetch checkpoint contract address, err %v", err)
+	}
+	return common.HexToAddress(addr)
+}
+
+// getCheckpoint retrieves the specified checkpoint or the latest one
+// through rpc request.
+func getCheckpoint(ctx *cli.Context, client *rpc.Client) *params.TrustedCheckpoint {
+	var checkpoint *params.TrustedCheckpoint
+
+	if ctx.GlobalIsSet(indexFlag.Name) {
+		var result [3]string
+		index := uint64(ctx.GlobalInt64(indexFlag.Name))
+		if err := client.Call(&result, "les_getCheckpoint", index); err != nil {
+			utils.Fatalf("Failed to get local checkpoint %v, please ensure the les API is exposed", err)
+		}
+		checkpoint = &params.TrustedCheckpoint{
+			SectionIndex: index,
+			SectionHead:  common.HexToHash(result[0]),
+			CHTRoot:      common.HexToHash(result[1]),
+			BloomRoot:    common.HexToHash(result[2]),
+		}
+	} else {
+		var result [4]string
+		err := client.Call(&result, "les_latestCheckpoint")
+		if err != nil {
+			utils.Fatalf("Failed to get local checkpoint %v, please ensure the les API is exposed", err)
+		}
+		index, err := strconv.ParseUint(result[0], 0, 64)
+		if err != nil {
+			utils.Fatalf("Failed to parse checkpoint index %v", err)
+		}
+		checkpoint = &params.TrustedCheckpoint{
+			SectionIndex: index,
+			SectionHead:  common.HexToHash(result[1]),
+			CHTRoot:      common.HexToHash(result[2]),
+			BloomRoot:    common.HexToHash(result[3]),
+		}
+	}
+	return checkpoint
+}
+
+// newContract creates a registrar contract instance with specified
+// contract address or the default contracts for mainnet or testnet.
+func newContract(client *rpc.Client) *registrar.Registrar {
+	addr := getContractAddr(client)
+	if addr == (common.Address{}) {
+		utils.Fatalf("No specified registrar contract address")
+	}
+	contract, err := registrar.NewRegistrar(addr, ethclient.NewClient(client))
+	if err != nil {
+		utils.Fatalf("Failed to setup registrar contract %s: %v", addr, err)
+	}
+	log.Info("Setup registrar contract", "address", addr)
+	return contract
+}
+
+// promptPassphrase prompts the user for a passphrase.
+// Set confirmation to true to require the user to confirm the passphrase.
+func promptPassphrase(confirmation bool) string {
+	passphrase, err := console.Stdin.PromptPassword("Passphrase: ")
+	if err != nil {
+		utils.Fatalf("Failed to read passphrase: %v", err)
+	}
+
+	if confirmation {
+		confirm, err := console.Stdin.PromptPassword("Repeat passphrase: ")
+		if err != nil {
+			utils.Fatalf("Failed to read passphrase confirmation: %v", err)
+		}
+		if passphrase != confirm {
+			utils.Fatalf("Passphrases do not match")
+		}
+	}
+	return passphrase
+}
+
+// getPassphrase obtains a passphrase given by the user. It first checks the
+// --password command line flag and ultimately prompts the user for a
+// passphrase.
+func getPassphrase(ctx *cli.Context) string {
+	passphraseFile := ctx.String(utils.PasswordFileFlag.Name)
+	if passphraseFile != "" {
+		content, err := ioutil.ReadFile(passphraseFile)
+		if err != nil {
+			utils.Fatalf("Failed to read passphrase file '%s': %v",
+				passphraseFile, err)
+		}
+		return strings.TrimRight(string(content), "\r\n")
+	}
+	// Otherwise prompt the user for the passphrase.
+	return promptPassphrase(false)
+}
+
+// getKey retrieves the user key through specified key file.
+func getKey(ctx *cli.Context) *keystore.Key {
+	// Read key from file.
+	keyFile := ctx.GlobalString(keyFileFlag.Name)
+	keyJson, err := ioutil.ReadFile(keyFile)
+	if err != nil {
+		utils.Fatalf("Failed to read the keyfile at '%s': %v", keyFile, err)
+	}
+	// Decrypt key with passphrase.
+	passphrase := getPassphrase(ctx)
+	key, err := keystore.DecryptKey(keyJson, passphrase)
+	if err != nil {
+		utils.Fatalf("Failed to decrypt user key '%s': %v", keyFile, err)
+	}
+	return key
+}

cmd/registrar/exec.go

@@ -0,0 +1,312 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of go-ethereum.
+//
+// go-ethereum is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// go-ethereum 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 General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"bytes"
+	"context"
+	"encoding/binary"
+	"fmt"
+	"math/big"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/cmd/utils"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/contracts/registrar"
+	"github.com/ethereum/go-ethereum/contracts/registrar/contract"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/ethclient"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/rpc"
+	"gopkg.in/urfave/cli.v1"
+)
+
+var commandDeployContract = cli.Command{
+	Name:  "deploy",
+	Usage: "Deploy a registrar contract with specified trusted signers.",
+	Flags: []cli.Flag{
+		signerFlag,
+		thresholdFlag,
+		nodeURLFlag,
+		keyFileFlag,
+		utils.PasswordFileFlag,
+	},
+	Action: utils.MigrateFlags(deployContract),
+}
+
+var commandSignCheckpoint = cli.Command{
+	Name:  "sign",
+	Usage: "Sign the checkpoint with the specified key",
+	Flags: []cli.Flag{
+		nodeURLFlag,
+		clefURLFlag,
+		indexFlag,
+		hashFlag,
+		addressFlag,
+		keyFileFlag,
+		signerFlag,
+		utils.PasswordFileFlag,
+	},
+	Action: utils.MigrateFlags(signCheckpoint),
+}
+
+var commandRegisterCheckpoint = cli.Command{
+	Name:  "register",
+	Usage: "Register specified checkpoint into contract",
+	Flags: []cli.Flag{
+		nodeURLFlag,
+		indexFlag,
+		signerFlag,
+		signatureFlag,
+		keyFileFlag,
+		utils.PasswordFileFlag,
+	},
+	Action: utils.MigrateFlags(registerCheckpoint),
+}
+
+// deployContract deploys the checkpoint registrar contract.
+//
+// Note the network where the contract is deployed depends on
+// the network where the connected node is located.
+func deployContract(ctx *cli.Context) error {
+	var addrs []common.Address
+	signers := strings.Split(ctx.GlobalString(signerFlag.Name), ",")
+	for _, account := range signers {
+		if trimmed := strings.TrimSpace(account); !common.IsHexAddress(trimmed) {
+			utils.Fatalf("Invalid account in --signer: %s", trimmed)
+		} else {
+			addrs = append(addrs, common.HexToAddress(account))
+		}
+	}
+
+	t := ctx.GlobalInt64(thresholdFlag.Name)
+	if t == 0 || int(t) > len(signers) {
+		utils.Fatalf("Invalid signature threshold %d", t)
+	}
+	addr, tx, _, err := contract.DeployContract(bind.NewKeyedTransactor(getKey(ctx).PrivateKey), newClient(ctx), addrs, big.NewInt(int64(params.CheckpointFrequency)),
+		big.NewInt(int64(params.CheckpointProcessConfirmations)), big.NewInt(t))
+	if err != nil {
+		utils.Fatalf("Failed to deploy registrar contract %v", err)
+	}
+	log.Info("Deployed registrar contract successfully", "address", addr, "tx", tx.Hash())
+	return nil
+}
+
+// signCheckpoint creates the signature for specific checkpoint
+// with local key. Only contract admins have the permission to
+// sign checkpoint.
+func signCheckpoint(ctx *cli.Context) error {
+	var (
+		offline bool // The indicator whether we sign checkpoint by offline.
+		chash   common.Hash
+		cindex  uint64
+		address common.Address
+
+		node *rpc.Client
+		c    *registrar.Registrar
+	)
+	if !ctx.GlobalIsSet(nodeURLFlag.Name) {
+		// Offline mode signing
+		offline = true
+		if !ctx.GlobalIsSet(hashFlag.Name) {
+			utils.Fatalf("Please specify checkpoint hash for offline mode signing")
+		}
+		chash = common.HexToHash(ctx.GlobalString(hashFlag.Name))
+		if !ctx.GlobalIsSet(indexFlag.Name) {
+			utils.Fatalf("Please specify checkpoint index for offline mode signing")
+		}
+		cindex = ctx.GlobalUint64(indexFlag.Name)
+		if !ctx.GlobalIsSet(addressFlag.Name) {
+			utils.Fatalf("Please specify contract address for offline mode signing")
+		}
+		address = common.HexToAddress(ctx.GlobalString(addressFlag.Name))
+	} else {
+		// Interactive mode signing
+		node = newRPCClient(ctx.GlobalString(nodeURLFlag.Name))
+		checkpoint := getCheckpoint(ctx, node)
+
+		chash = checkpoint.Hash()
+		cindex = checkpoint.SectionIndex
+		address = getContractAddr(node)
+
+		reqCtx, cancelFn := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancelFn()
+
+		// Check the validity of checkpoint.
+		head, err := ethclient.NewClient(node).HeaderByNumber(reqCtx, nil)
+		if err != nil {
+			return err
+		}
+		num := head.Number.Uint64()
+		if num < ((cindex+1)*params.CheckpointFrequency + params.CheckpointProcessConfirmations) {
+			utils.Fatalf("Invalid future checkpoint")
+		}
+		c = newContract(node)
+		latest, _, h, err := c.Contract().GetLatestCheckpoint(nil)
+		if err != nil {
+			return err
+		}
+		if cindex < latest {
+			utils.Fatalf("Checkpoint is too old")
+		}
+		if cindex == latest && (latest != 0 || h.Uint64() != 0) {
+			utils.Fatalf("Stale checkpoint, latest registered %d, given %d", latest, cindex)
+		}
+	}
+	var (
+		signature string
+		signer    string
+	)
+	// isAdmin checks whether the specified signer is admin.
+	isAdmin := func(addr common.Address) error {
+		signers, err := c.Contract().GetAllAdmin(nil)
+		if err != nil {
+			return err
+		}
+		for _, s := range signers {
+			if s == addr {
+				return nil
+			}
+		}
+		return fmt.Errorf("signer %v is not the admin", addr.Hex())
+	}
+	switch {
+	case ctx.GlobalIsSet(clefURLFlag.Name):
+		// Sign checkpoint in clef mode.
+		signer = ctx.GlobalString(signerFlag.Name)
+
+		if !offline {
+			if err := isAdmin(common.HexToAddress(signer)); err != nil {
+				return err
+			}
+		}
+		clef := newRPCClient(ctx.GlobalString(clefURLFlag.Name))
+		p := make(map[string]string)
+		buf := make([]byte, 8)
+		binary.BigEndian.PutUint64(buf, cindex)
+		p["address"] = address.Hex()
+		p["message"] = hexutil.Encode(append(buf, chash.Bytes()...))
+		if err := clef.Call(&signature, "account_signData", "data/validator", signer, p); err != nil {
+			utils.Fatalf("Failed to sign checkpoint, err %v", err)
+		}
+	case ctx.GlobalIsSet(keyFileFlag.Name):
+		// Sign checkpoint in raw private key file mode.
+		key := getKey(ctx)
+		signer = key.Address.Hex()
+
+		if !offline {
+			if err := isAdmin(key.Address); err != nil {
+				return err
+			}
+		}
+		buf := make([]byte, 8)
+		binary.BigEndian.PutUint64(buf, cindex)
+		data := append([]byte{0x19, 0x00}, append(address[:], append(buf, chash.Bytes()...)...)...)
+		sig, err := crypto.Sign(crypto.Keccak256(data), key.PrivateKey)
+		if err != nil {
+			utils.Fatalf("Failed to sign checkpoint, err %v", err)
+		}
+		sig[64] += 27 // Transform V from 0/1 to 27/28 according to the yellow paper
+		signature = common.Bytes2Hex(sig)
+	default:
+		utils.Fatalf("Please specify clef URL or private key file path to sign checkpoint")
+	}
+	log.Info("Successfully signed checkpoint", "index", cindex, "hash", chash.Hex(), "address", address.Hex(), "signer", signer, "signature", signature)
+	return nil
+}
+
+type Signer struct {
+	addr common.Address
+	sig  []byte
+}
+type Signers []Signer
+
+func (s Signers) Len() int           { return len(s) }
+func (s Signers) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
+func (s Signers) Less(i, j int) bool { return bytes.Compare(s[i].addr.Bytes(), s[j].addr.Bytes()) < 0 }
+
+// registerCheckpoint registers the specified checkpoint which generated by connected
+// node with a authorised private key.
+func registerCheckpoint(ctx *cli.Context) error {
+	var (
+		addrs   []common.Address
+		sigs    [][]byte
+		signers Signers
+	)
+	signerStrs := strings.Split(ctx.GlobalString(signerFlag.Name), ",")
+	for _, account := range signerStrs {
+		if trimmed := strings.TrimSpace(account); !common.IsHexAddress(trimmed) {
+			utils.Fatalf("Invalid account in --signer: %s", trimmed)
+		} else {
+			addrs = append(addrs, common.HexToAddress(account))
+		}
+	}
+	sigStrs := strings.Split(ctx.GlobalString(signatureFlag.Name), ",")
+	for _, sig := range sigStrs {
+		trimmed := strings.TrimSpace(sig)
+		if strings.HasPrefix(trimmed, "0x") {
+			trimmed = trimmed[2:]
+		}
+		if len(trimmed) != 130 {
+			utils.Fatalf("Invalid signature in --signature: %s", trimmed)
+		} else {
+			sigs = append(sigs, common.Hex2Bytes(trimmed))
+		}
+	}
+	if len(addrs) != len(sigs) {
+		utils.Fatalf("The length of signer and corresponding signature mismatch")
+	}
+	for i := 0; i < len(addrs); i++ {
+		signers = append(signers, Signer{addr: addrs[i], sig: sigs[i]})
+	}
+	sort.Sort(signers)
+	sigs = sigs[:0]
+	for i := 0; i < len(signers); i++ {
+		sigs = append(sigs, signers[i].sig)
+	}
+
+	reqCtx, cancelFn := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancelFn()
+
+	// Retrieve recent header info to protect replay attack.
+	node := newRPCClient(ctx.GlobalString(nodeURLFlag.Name))
+	head, err := ethclient.NewClient(node).HeaderByNumber(reqCtx, nil)
+	if err != nil {
+		return err
+	}
+	num := head.Number.Uint64()
+	recent, err := ethclient.NewClient(node).HeaderByNumber(reqCtx, big.NewInt(int64(num-128)))
+	if err != nil {
+		return err
+	}
+	var (
+		c          = newContract(node)
+		key        = getKey(ctx)
+		checkpoint = getCheckpoint(ctx, node)
+	)
+	tx, err := c.RegisterCheckpoint(key.PrivateKey, checkpoint.SectionIndex, checkpoint.Hash().Bytes(), recent.Number, recent.Hash(), sigs)
+	if err != nil {
+		utils.Fatalf("Register contract failed %v", err)
+	}
+	log.Info("Successfully registered checkpoint", "index", checkpoint.SectionIndex, "hash", checkpoint.Hash(), "signumber", len(signers), "txhash", tx.Hash())
+	return nil
+}

cmd/registrar/main.go

@@ -0,0 +1,126 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of go-ethereum.
+//
+// go-ethereum is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// go-ethereum 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 General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
+
+// registrar is a utility that can be used to query checkpoint information
+// and register stable checkpoint into the contract.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/ethereum/go-ethereum/cmd/utils"
+	"github.com/ethereum/go-ethereum/common/fdlimit"
+	"github.com/ethereum/go-ethereum/log"
+	"gopkg.in/urfave/cli.v1"
+)
+
+const (
+	commandHelperTemplate = `{{.Name}}{{if .Subcommands}} command{{end}}{{if .Flags}} [command options]{{end}} [arguments...]
+{{if .Description}}{{.Description}}
+{{end}}{{if .Subcommands}}
+SUBCOMMANDS:
+	{{range .Subcommands}}{{.Name}}{{with .ShortName}}, {{.}}{{end}}{{ "\t" }}{{.Usage}}
+	{{end}}{{end}}{{if .Flags}}
+OPTIONS:
+{{range $.Flags}}{{"\t"}}{{.}}
+{{end}}
+{{end}}`
+)
+
+var (
+	// Git SHA1 commit hash of the release (set via linker flags)
+	gitCommit = ""
+	gitDate   = ""
+)
+
+var app *cli.App
+
+func init() {
+	app = utils.NewApp(gitCommit, gitDate, "ethereum checkpoint helper tool")
+	app.Commands = []cli.Command{
+		commandQueryAdmin,
+		commandQueryCheckpoint,
+		commandDeployContract,
+		commandSignCheckpoint,
+		commandRegisterCheckpoint,
+	}
+	app.Flags = []cli.Flag{
+		indexFlag,
+		hashFlag,
+		addressFlag,
+		thresholdFlag,
+		keyFileFlag,
+		nodeURLFlag,
+		clefURLFlag,
+		signerFlag,
+		signatureFlag,
+		utils.PasswordFileFlag,
+	}
+	cli.CommandHelpTemplate = commandHelperTemplate
+}
+
+// Commonly used command line flags.
+var (
+	indexFlag = cli.Int64Flag{
+		Name:  "index",
+		Usage: "Checkpoint index (query latest from remote node if not specified)",
+	}
+	hashFlag = cli.StringFlag{
+		Name:  "hash",
+		Usage: "Checkpoint hash (query latest from remote node if not specified)",
+	}
+	addressFlag = cli.StringFlag{
+		Name:  "address",
+		Usage: "Checkpoint contract address (query from remote node if not specified)",
+	}
+	thresholdFlag = cli.Int64Flag{
+		Name:  "threshold",
+		Usage: "Minimal number of signatures required to approve a checkpoint",
+	}
+	keyFileFlag = cli.StringFlag{
+		Name:  "keyfile",
+		Usage: "The private key file (keyfile signature is not recommended)",
+	}
+	nodeURLFlag = cli.StringFlag{
+		Name:  "rpc",
+		Value: "http://localhost:8545",
+		Usage: "The rpc endpoint of a local or remote geth node",
+	}
+	clefURLFlag = cli.StringFlag{
+		Name:  "clef",
+		Value: "http://localhost:8550",
+		Usage: "The rpc endpoint of clef",
+	}
+	signerFlag = cli.StringFlag{
+		Name:  "signer",
+		Usage: "Comma separated accounts of trusted checkpoint signers",
+	}
+	signatureFlag = cli.StringFlag{
+		Name:  "signature",
+		Usage: "Comma separated checkpoint signatures to submit",
+	}
+)
+
+func main() {
+	log.Root().SetHandler(log.LvlFilterHandler(log.LvlInfo, log.StreamHandler(os.Stderr, log.TerminalFormat(true))))
+	fdlimit.Raise(2048)
+
+	if err := app.Run(os.Args); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}

cmd/registrar/query.go

@@ -0,0 +1,69 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of go-ethereum.
+//
+// go-ethereum is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// go-ethereum 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 General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/cmd/utils"
+	"github.com/ethereum/go-ethereum/common"
+	"gopkg.in/urfave/cli.v1"
+)
+
+var commandQueryAdmin = cli.Command{
+	Name:  "queryadmin",
+	Usage: "Fetch the admin list of specified registrar contract",
+	Flags: []cli.Flag{
+		nodeURLFlag,
+	},
+	Action: utils.MigrateFlags(queryAdmin),
+}
+
+var commandQueryCheckpoint = cli.Command{
+	Name:  "querycheckpoint",
+	Usage: "Fetch the latest registered checkpoint in the registrar contract",
+	Flags: []cli.Flag{
+		nodeURLFlag,
+	},
+	Action: utils.MigrateFlags(queryCheckpoint),
+}
+
+// queryAdmin fetches the admin list of specified registrar contract.
+func queryAdmin(ctx *cli.Context) error {
+	contract := newContract(newRPCClient(ctx.GlobalString(nodeURLFlag.Name)))
+	admins, err := contract.Contract().GetAllAdmin(nil)
+	if err != nil {
+		return err
+	}
+	fmt.Println("Total admin number", len(admins))
+	for i, admin := range admins {
+		fmt.Printf("Admin %d => %s\n", i+1, admin.Hex())
+	}
+	return nil
+}
+
+// queryCheckpoint fetches the checkpoint hash with specified index from
+// registrar contract.
+func queryCheckpoint(ctx *cli.Context) error {
+	contract := newContract(newRPCClient(ctx.GlobalString(nodeURLFlag.Name)))
+	index, checkpoint, height, err := contract.Contract().GetLatestCheckpoint(nil)
+	if err != nil {
+		return err
+	}
+	fmt.Printf("Latest checkpoint(registered at height #%d) %d => %s\n", height, index, common.Hash(checkpoint).Hex())
+	return nil
+}

contracts/chequebook/cheque_test.go

@@ -42,7 +42,7 @@ var (
 )
 
 func newTestBackend() *backends.SimulatedBackend {
-	return backends.NewSimulatedBackend(core.GenesisAlloc{
+	return backends.NewSimulatedBackend(nil, core.GenesisAlloc{
 		addr0: {Balance: big.NewInt(1000000000)},
 		addr1: {Balance: big.NewInt(1000000000)},
 		addr2: {Balance: big.NewInt(1000000000)},

contracts/ens/ens_test.go

@@ -39,7 +39,7 @@ var (
 )
 
 func TestENS(t *testing.T) {
-	contractBackend := backends.NewSimulatedBackend(core.GenesisAlloc{addr: {Balance: big.NewInt(1000000000)}}, 10000000)
+	contractBackend := backends.NewSimulatedBackend(nil, core.GenesisAlloc{addr: {Balance: big.NewInt(1000000000)}}, 10000000)
 	transactOpts := bind.NewKeyedTransactor(key)
 
 	ensAddr, ens, err := DeployENS(transactOpts, contractBackend)

contracts/registrar/contract/registrar.sol

@@ -0,0 +1,175 @@
+pragma solidity ^0.5.2;
+
+/**
+ * @title Registrar
+ * @author Gary Rong<garyrong@ethereum.org>, Martin Swende <martin.swende@ethereum.org>
+ * @dev Implementation of the blockchain checkpoint registrar.
+ */
+contract Registrar {
+    /*
+        Events
+    */
+
+    // NewCheckpointVote is emitted when a new checkpoint proposal receives a vote.
+    event NewCheckpointVote(uint64 indexed index, bytes32 checkpointHash, uint8 v, bytes32 r, bytes32 s);
+
+    /*
+        Public Functions
+    */
+    constructor(address[] memory _adminlist, uint _sectionSize, uint _processConfirms, uint _threshold) public {
+        for (uint i = 0; i < _adminlist.length; i++) {
+            admins[_adminlist[i]] = true;
+            adminList.push(_adminlist[i]);
+        }
+        sectionSize = _sectionSize;
+        processConfirms = _processConfirms;
+        threshold = _threshold;
+    }
+
+    /**
+     * @dev Get latest stable checkpoint information.
+     * @return section index
+     * @return checkpoint hash
+     * @return block height associated with checkpoint
+     */
+    function GetLatestCheckpoint()
+    view
+    public
+    returns(uint64, bytes32, uint) {
+        return (sectionIndex, hash, height);
+    }
+
+    // SetCheckpoint sets  a new checkpoint. It accepts a list of signatures
+    // @_recentNumber: a recent blocknumber, for replay protection
+    // @_recentHash : the hash of `_recentNumber`
+    // @_hash : the hash to set at _sectionIndex
+    // @_sectionIndex : the section index to set
+    // @v : the list of v-values
+    // @r : the list or r-values
+    // @s : the list of s-values
+    function SetCheckpoint(
+        uint _recentNumber,
+        bytes32 _recentHash,
+        bytes32 _hash,
+        uint64 _sectionIndex,
+        uint8[] memory v,
+        bytes32[] memory r,
+        bytes32[] memory s)
+        public
+        returns (bool)
+    {
+        // Ensure the sender is authorized.
+        require(admins[msg.sender]);
+
+        // These checks replay protection, so it cannot be replayed on forks,
+        // accidentally or intentionally
+        require(blockhash(_recentNumber) == _recentHash);
+
+        // Ensure the batch of signatures are valid.
+        require(v.length == r.length);
+        require(v.length == s.length);
+
+        // Filter out "future" checkpoint.
+        if (block.number < (_sectionIndex+1)*sectionSize+processConfirms) {
+            return false;
+        }
+        // Filter out "old" announcement
+        if (_sectionIndex < sectionIndex) {
+            return false;
+        }
+        // Filter out "stale" announcement
+        if (_sectionIndex == sectionIndex && (_sectionIndex != 0 || height != 0)) {
+            return false;
+        }
+        // Filter out "invalid" announcement
+        if (_hash == ""){
+            return false;
+        }
+
+        // EIP 191 style signatures
+        //
+        // Arguments when calculating hash to validate
+        // 1: byte(0x19) - the initial 0x19 byte
+        // 2: byte(0) - the version byte (data with intended validator)
+        // 3: this - the validator address
+        // --  Application specific data
+        // 4 : checkpoint section_index(uint64)
+        // 5 : checkpoint hash (bytes32)
+        //     hash = keccak256(checkpoint_index, section_head, cht_root, bloom_root)
+        bytes32 signedHash = keccak256(abi.encodePacked(byte(0x19), byte(0), this, _sectionIndex, _hash));
+
+        address lastVoter = address(0);
+
+        // In order for us not to have to maintain a mapping of who has already
+        // voted, and we don't want to count a vote twice, the signatures must
+        // be submitted in strict ordering.
+        for (uint idx = 0; idx < v.length; idx++){
+            address signer = ecrecover(signedHash, v[idx], r[idx], s[idx]);
+            require(admins[signer]);
+            require(uint256(signer) > uint256(lastVoter));
+            lastVoter = signer;
+            emit NewCheckpointVote(_sectionIndex, _hash, v[idx], r[idx], s[idx]);
+
+            // Sufficient signatures present, update latest checkpoint.
+            if (idx+1 >= threshold){
+                hash = _hash;
+                height = block.number;
+                sectionIndex = _sectionIndex;
+                return true;
+            }
+        }
+        // We shouldn't wind up here, reverting un-emits the events
+        revert();
+    }
+
+    /**
+     * @dev Get all admin addresses
+     * @return address list
+     */
+    function GetAllAdmin()
+    public
+    view
+    returns(address[] memory)
+    {
+        address[] memory ret = new address[](adminList.length);
+        for (uint i = 0; i < adminList.length; i++) {
+            ret[i] = adminList[i];
+        }
+        return ret;
+    }
+
+    /*
+        Fields
+    */
+    // A map of admin users who have the permission to update CHT and bloom Trie root
+    mapping(address => bool) admins;
+
+    // A list of admin users so that we can obtain all admin users.
+    address[] adminList;
+
+    // Latest stored section id
+    uint64 sectionIndex;
+
+    // The block height associated with latest registered checkpoint.
+    uint height;
+
+    // The hash of latest registered checkpoint.
+    bytes32 hash;
+
+    // The frequency for creating a checkpoint
+    //
+    // The default value should be the same as the checkpoint size(32768) in the ethereum.
+    uint sectionSize;
+
+    // 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.
+    //
+    // The default value should be the same as the checkpoint process confirmations(256)
+    // in the ethereum.
+    uint processConfirms;
+
+    // The required signatures to finalize a stable checkpoint.
+    uint threshold;
+}
+

contracts/registrar/registrar.go

@@ -0,0 +1,89 @@
+// Copyright 2018 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 registrar
+
+//go:generate abigen --sol contract/registrar.sol --pkg contract --out contract/registrar.go
+
+import (
+	"crypto/ecdsa"
+	"errors"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/contracts/registrar/contract"
+	"github.com/ethereum/go-ethereum/core/types"
+)
+
+type Registrar struct {
+	contract *contract.Contract
+}
+
+// NewRegistrar binds checkpoint contract and returns a registrar instance.
+func NewRegistrar(contractAddr common.Address, backend bind.ContractBackend) (*Registrar, error) {
+	c, err := contract.NewContract(contractAddr, backend)
+	if err != nil {
+		return nil, err
+	}
+	return &Registrar{contract: c}, nil
+}
+
+// Contract returns the underlying contract instance.
+func (registrar *Registrar) Contract() *contract.Contract {
+	return registrar.contract
+}
+
+// LookupCheckpointEvent searches checkpoint event for specific section in the
+// given log batches.
+func (registrar *Registrar) LookupCheckpointEvent(blockLogs [][]*types.Log, section uint64, hash common.Hash) []*contract.ContractNewCheckpointVote {
+	var votes []*contract.ContractNewCheckpointVote
+
+	for _, logs := range blockLogs {
+		for _, log := range logs {
+			event, err := registrar.contract.ParseNewCheckpointVote(*log)
+			if err != nil {
+				continue
+			}
+			if event.Index == section && common.Hash(event.CheckpointHash) == hash {
+				votes = append(votes, event)
+			}
+		}
+	}
+	return votes
+}
+
+// RegisterCheckpoint registers the checkpoint with a batch of associated signatures
+// that are collected off-chain and sorted by lexicographical order.
+//
+// Notably all signatures given should be transformed to "ethereum style" which transforms
+// v from 0/1 to 27/28 according to the yellow paper.
+func (registrar *Registrar) RegisterCheckpoint(key *ecdsa.PrivateKey, index uint64, hash []byte, rnum *big.Int, rhash [32]byte, sigs [][]byte) (*types.Transaction, error) {
+	var (
+		r [][32]byte
+		s [][32]byte
+		v []uint8
+	)
+	for i := 0; i < len(sigs); i++ {
+		if len(sigs[i]) != 65 {
+			return nil, errors.New("invalid signature")
+		}
+		r = append(r, common.BytesToHash(sigs[i][:32]))
+		s = append(s, common.BytesToHash(sigs[i][32:64]))
+		v = append(v, sigs[i][64])
+	}
+	return registrar.contract.SetCheckpoint(bind.NewKeyedTransactor(key), rnum, rhash, common.BytesToHash(hash), index, v, r, s)
+}

contracts/registrar/registrar_test.go

@@ -0,0 +1,327 @@
+// Copyright 2018 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 registrar
+
+import (
+	"bytes"
+	"crypto/ecdsa"
+	"encoding/binary"
+	"errors"
+	"math/big"
+	"reflect"
+	"sort"
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/accounts/abi/bind/backends"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/contracts/registrar/contract"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+var (
+	emptyHash = [32]byte{}
+
+	checkpoint0 = params.TrustedCheckpoint{
+		SectionIndex: 0,
+		SectionHead:  common.HexToHash("0x7fa3c32f996c2bfb41a1a65b3d8ea3e0a33a1674cde43678ad6f4235e764d17d"),
+		CHTRoot:      common.HexToHash("0x98fc5d3de23a0fecebad236f6655533c157d26a1aedcd0852a514dc1169e6350"),
+		BloomRoot:    common.HexToHash("0x99b5adb52b337fe25e74c1c6d3835b896bd638611b3aebddb2317cce27a3f9fa"),
+	}
+	checkpoint1 = params.TrustedCheckpoint{
+		SectionIndex: 1,
+		SectionHead:  common.HexToHash("0x2d4dee68102125e59b0cc61b176bd89f0d12b3b91cfaf52ef8c2c82fb920c2d2"),
+		CHTRoot:      common.HexToHash("0x7d428008ece3b4c4ef5439f071930aad0bb75108d381308df73beadcd01ded95"),
+		BloomRoot:    common.HexToHash("0x652571f7736de17e7bbb427ac881474da684c6988a88bf51b10cca9a2ee148f4"),
+	}
+	checkpoint2 = params.TrustedCheckpoint{
+		SectionIndex: 2,
+		SectionHead:  common.HexToHash("0x61c0de578c0115b1dff8ef39aa600588c7c6ecb8a2f102003d7cf4c4146e9291"),
+		CHTRoot:      common.HexToHash("0x407a08a407a2bc3838b74ca3eb206903c9c8a186ccf5ef14af07794efff1970b"),
+		BloomRoot:    common.HexToHash("0x058b4161f558ce295a92925efc57f34f9210d5a30088d7475c183e0d3e58f5ac"),
+	}
+)
+
+var (
+	// The block frequency for creating checkpoint(only used in test)
+	sectionSize = big.NewInt(512)
+
+	// The number of confirmations needed to generate a checkpoint(only used in test).
+	processConfirms = big.NewInt(4)
+)
+
+// validateOperation executes the operation, watches and delivers all events fired by the backend and ensures the
+// correctness by assert function.
+func validateOperation(t *testing.T, c *contract.Contract, backend *backends.SimulatedBackend, operation func(),
+	assert func(<-chan *contract.ContractNewCheckpointVote) error, opName string) {
+	// Watch all events and deliver them to assert function
+	var (
+		sink   = make(chan *contract.ContractNewCheckpointVote)
+		sub, _ = c.WatchNewCheckpointVote(nil, sink, nil)
+	)
+	defer func() {
+		// Close all subscribers
+		sub.Unsubscribe()
+	}()
+	operation()
+
+	// flush pending block
+	backend.Commit()
+	if err := assert(sink); err != nil {
+		t.Errorf("operation {%s} failed, err %s", opName, err)
+	}
+}
+
+// validateEvents checks that the correct number of contract events
+// fired by contract backend.
+func validateEvents(target int, sink interface{}) (bool, []reflect.Value) {
+	chanval := reflect.ValueOf(sink)
+	chantyp := chanval.Type()
+	if chantyp.Kind() != reflect.Chan || chantyp.ChanDir()&reflect.RecvDir == 0 {
+		return false, nil
+	}
+	count := 0
+	var recv []reflect.Value
+	timeout := time.After(1 * time.Second)
+	cases := []reflect.SelectCase{{Chan: chanval, Dir: reflect.SelectRecv}, {Chan: reflect.ValueOf(timeout), Dir: reflect.SelectRecv}}
+	for {
+		chose, v, _ := reflect.Select(cases)
+		if chose == 1 {
+			// Not enough event received
+			return false, nil
+		}
+		count += 1
+		recv = append(recv, v)
+		if count == target {
+			break
+		}
+	}
+	done := time.After(50 * time.Millisecond)
+	cases = cases[:1]
+	cases = append(cases, reflect.SelectCase{Chan: reflect.ValueOf(done), Dir: reflect.SelectRecv})
+	chose, _, _ := reflect.Select(cases)
+	// If chose equal 0, it means receiving redundant events.
+	return chose == 1, recv
+}
+
+func signCheckpoint(addr common.Address, privateKey *ecdsa.PrivateKey, index uint64, hash common.Hash) []byte {
+	// EIP 191 style signatures
+	//
+	// Arguments when calculating hash to validate
+	// 1: byte(0x19) - the initial 0x19 byte
+	// 2: byte(0) - the version byte (data with intended validator)
+	// 3: this - the validator address
+	// --  Application specific data
+	// 4 : checkpoint section_index(uint64)
+	// 5 : checkpoint hash (bytes32)
+	//     hash = keccak256(checkpoint_index, section_head, cht_root, bloom_root)
+	buf := make([]byte, 8)
+	binary.BigEndian.PutUint64(buf, index)
+	data := append([]byte{0x19, 0x00}, append(addr.Bytes(), append(buf, hash.Bytes()...)...)...)
+	sig, _ := crypto.Sign(crypto.Keccak256(data), privateKey)
+	sig[64] += 27 // Transform V from 0/1 to 27/28 according to the yellow paper
+	return sig
+}
+
+// assertSignature verifies whether the recovered signers are equal with expected.
+func assertSignature(addr common.Address, index uint64, hash [32]byte, r, s [32]byte, v uint8, expect common.Address) bool {
+	buf := make([]byte, 8)
+	binary.BigEndian.PutUint64(buf, index)
+	data := append([]byte{0x19, 0x00}, append(addr.Bytes(), append(buf, hash[:]...)...)...)
+	pubkey, err := crypto.Ecrecover(crypto.Keccak256(data), append(r[:], append(s[:], v-27)...))
+	if err != nil {
+		return false
+	}
+	var signer common.Address
+	copy(signer[:], crypto.Keccak256(pubkey[1:])[12:])
+	return bytes.Compare(signer.Bytes(), expect.Bytes()) == 0
+}
+
+type Account struct {
+	key  *ecdsa.PrivateKey
+	addr common.Address
+}
+type Accounts []Account
+
+func (a Accounts) Len() int           { return len(a) }
+func (a Accounts) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a Accounts) Less(i, j int) bool { return bytes.Compare(a[i].addr.Bytes(), a[j].addr.Bytes()) < 0 }
+
+func TestCheckpointRegister(t *testing.T) {
+	// Initialize test accounts
+	var accounts Accounts
+	for i := 0; i < 3; i++ {
+		key, _ := crypto.GenerateKey()
+		addr := crypto.PubkeyToAddress(key.PublicKey)
+		accounts = append(accounts, Account{key: key, addr: addr})
+	}
+	sort.Sort(accounts)
+
+	// Deploy registrar contract
+	transactOpts := bind.NewKeyedTransactor(accounts[0].key)
+	contractBackend := backends.NewSimulatedBackend(nil, core.GenesisAlloc{accounts[0].addr: {Balance: big.NewInt(1000000000)}, accounts[1].addr: {Balance: big.NewInt(1000000000)}, accounts[2].addr: {Balance: big.NewInt(1000000000)}}, 10000000)
+	// 3 trusted signers, threshold 2
+	contractAddr, _, c, err := contract.DeployContract(transactOpts, contractBackend, []common.Address{accounts[0].addr, accounts[1].addr, accounts[2].addr}, sectionSize, processConfirms, big.NewInt(2))
+	if err != nil {
+		t.Error("Failed to deploy registrar contract", err)
+	}
+	contractBackend.Commit()
+
+	// getRecent returns block height and hash of the head parent.
+	getRecent := func() (*big.Int, common.Hash) {
+		parentNumber := new(big.Int).Sub(contractBackend.Blockchain().CurrentHeader().Number, big.NewInt(1))
+		parentHash := contractBackend.Blockchain().CurrentHeader().ParentHash
+		return parentNumber, parentHash
+	}
+	// collectSig generates specified number signatures.
+	collectSig := func(index uint64, hash common.Hash, n int, unauthorized *ecdsa.PrivateKey) (v []uint8, r [][32]byte, s [][32]byte) {
+		for i := 0; i < n; i++ {
+			sig := signCheckpoint(contractAddr, accounts[i].key, index, hash)
+			if unauthorized != nil {
+				sig = signCheckpoint(contractAddr, unauthorized, index, hash)
+			}
+			r = append(r, common.BytesToHash(sig[:32]))
+			s = append(s, common.BytesToHash(sig[32:64]))
+			v = append(v, sig[64])
+		}
+		return v, r, s
+	}
+	// assert checks whether the current contract status is same with
+	// the expected.
+	assert := func(index uint64, hash [32]byte, height *big.Int) error {
+		lindex, lhash, lheight, err := c.GetLatestCheckpoint(nil)
+		if err != nil {
+			return err
+		}
+		if lindex != index {
+			return errors.New("latest checkpoint index mismatch")
+		}
+		if bytes.Compare(lhash[:], hash[:]) != 0 {
+			return errors.New("latest checkpoint hash mismatch")
+		}
+		if lheight.Cmp(height) != 0 {
+			return errors.New("latest checkpoint height mismatch")
+		}
+		return nil
+	}
+
+	// Test future checkpoint registration
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(0, checkpoint0.Hash(), 2, nil)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint0.Hash(), 0, v, r, s)
+	}, func(events <-chan *contract.ContractNewCheckpointVote) error {
+		return assert(0, emptyHash, big.NewInt(0))
+	}, "test future checkpoint registration")
+
+	contractBackend.InsertEmptyBlocks(int(sectionSize.Uint64() + processConfirms.Uint64()))
+
+	// Test transaction replay protection
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(0, checkpoint0.Hash(), 2, nil)
+		hash = common.HexToHash("deadbeef")
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint0.Hash(), 0, v, r, s)
+	}, func(events <-chan *contract.ContractNewCheckpointVote) error {
+		return assert(0, emptyHash, big.NewInt(0))
+	}, "test transaction replay protection")
+
+	// Test unauthorized signature checking
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		u, _ := crypto.GenerateKey()
+		v, r, s := collectSig(0, checkpoint0.Hash(), 2, u)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint0.Hash(), 0, v, r, s)
+	}, func(events <-chan *contract.ContractNewCheckpointVote) error {
+		return assert(0, emptyHash, big.NewInt(0))
+	}, "test unauthorized signature checking")
+
+	// Test un-multi-signature checkpoint registration
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(0, checkpoint0.Hash(), 1, nil)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint0.Hash(), 0, v, r, s)
+	}, func(events <-chan *contract.ContractNewCheckpointVote) error {
+		return assert(0, emptyHash, big.NewInt(0))
+	}, "test un-multi-signature checkpoint registration")
+
+	// Test valid checkpoint registration
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(0, checkpoint0.Hash(), 2, nil)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint0.Hash(), 0, v, r, s)
+	}, func(events <-chan *contract.ContractNewCheckpointVote) error {
+		if valid, recv := validateEvents(2, events); !valid {
+			return errors.New("receive incorrect number of events")
+		} else {
+			for i := 0; i < len(recv); i++ {
+				event := recv[i].Interface().(*contract.ContractNewCheckpointVote)
+				if !assertSignature(contractAddr, event.Index, event.CheckpointHash, event.R, event.S, event.V, accounts[i].addr) {
+					return errors.New("recover signer failed")
+				}
+			}
+		}
+		number, _ := getRecent()
+		return assert(0, checkpoint0.Hash(), number.Add(number, big.NewInt(1)))
+	}, "test valid checkpoint registration")
+
+	distance := 3*sectionSize.Uint64() + processConfirms.Uint64() - contractBackend.Blockchain().CurrentHeader().Number.Uint64()
+	contractBackend.InsertEmptyBlocks(int(distance))
+
+	// Test uncontinuous checkpoint registration
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(2, checkpoint2.Hash(), 2, nil)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint2.Hash(), 2, v, r, s)
+	}, func(events <-chan *contract.ContractNewCheckpointVote) error {
+		if valid, recv := validateEvents(2, events); !valid {
+			return errors.New("receive incorrect number of events")
+		} else {
+			for i := 0; i < len(recv); i++ {
+				event := recv[i].Interface().(*contract.ContractNewCheckpointVote)
+				if !assertSignature(contractAddr, event.Index, event.CheckpointHash, event.R, event.S, event.V, accounts[i].addr) {
+					return errors.New("recover signer failed")
+				}
+			}
+		}
+		number, _ := getRecent()
+		return assert(2, checkpoint2.Hash(), number.Add(number, big.NewInt(1)))
+	}, "test uncontinuous checkpoint registration")
+
+	// Test old checkpoint registration
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(1, checkpoint1.Hash(), 2, nil)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint1.Hash(), 1, v, r, s)
+	}, func(events <-chan *contract.ContractNewCheckpointVote) error {
+		number, _ := getRecent()
+		return assert(2, checkpoint2.Hash(), number)
+	}, "test uncontinuous checkpoint registration")
+
+	// Test stale checkpoint registration
+	validateOperation(t, c, contractBackend, func() {
+		number, hash := getRecent()
+		v, r, s := collectSig(2, checkpoint2.Hash(), 2, nil)
+		c.SetCheckpoint(transactOpts, number, hash, checkpoint2.Hash(), 2, v, r, s)
+	}, func(events <-chan *contract.ContractNewCheckpointVote) error {
+		number, _ := getRecent()
+		return assert(2, checkpoint2.Hash(), number.Sub(number, big.NewInt(1)))
+	}, "test stale checkpoint registration")
+}

core/chain_indexer.go

@@ -128,12 +128,13 @@ func (c *ChainIndexer) AddCheckpoint(section uint64, shead common.Hash) {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 
+	// Short circuit if the given checkpoint is below than local's.
+	if c.checkpointSections >= section+1 || section < c.storedSections {
+		return
+	}
 	c.checkpointSections = section + 1
 	c.checkpointHead = shead
 
-	if section < c.storedSections {
-		return
-	}
 	c.setSectionHead(section, shead)
 	c.setValidSections(section + 1)
 }

eth/backend.go

@@ -26,6 +26,7 @@ import (
 	"sync/atomic"
 
 	"github.com/ethereum/go-ethereum/accounts"
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/consensus"
@@ -57,6 +58,7 @@ type LesServer interface {
 	APIs() []rpc.API
 	Protocols() []p2p.Protocol
 	SetBloomBitsIndexer(bbIndexer *core.ChainIndexer)
+	SetContractBackend(bind.ContractBackend)
 }
 
 // Ethereum implements the Ethereum full node service.
@@ -99,6 +101,14 @@ func (s *Ethereum) AddLesServer(ls LesServer) {
 	ls.SetBloomBitsIndexer(s.bloomIndexer)
 }
 
+// SetClient sets a rpc client which connecting to our local node.
+func (s *Ethereum) SetContractBackend(backend bind.ContractBackend) {
+	// Pass the rpc client to les server if it is enabled.
+	if s.lesServer != nil {
+		s.lesServer.SetContractBackend(backend)
+	}
+}
+
 // New creates a new Ethereum object (including the
 // initialisation of the common Ethereum object)
 func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
@@ -268,6 +278,11 @@ func (s *Ethereum) APIs() []rpc.API {
 	// Append any APIs exposed explicitly by the consensus engine
 	apis = append(apis, s.engine.APIs(s.BlockChain())...)
 
+	// Append any APIs exposed explicitly by the les server
+	if s.lesServer != nil {
+		apis = append(apis, s.lesServer.APIs()...)
+	}
+
 	// Append all the local APIs and return
 	return append(apis, []rpc.API{
 		{

internal/web3ext/web3ext.go

@@ -32,6 +32,7 @@ var Modules = map[string]string{
 	"shh":        ShhJs,
 	"swarmfs":    SwarmfsJs,
 	"txpool":     TxpoolJs,
+	"les":        LESJs,
 }
 
 const ChequebookJs = `
@@ -760,3 +761,28 @@ web3._extend({
 	]
 });
 `
+
+const LESJs = `
+web3._extend({
+	property: 'les',
+	methods: 
+	[
+		new web3._extend.Method({
+			name: 'getCheckpoint',
+			call: 'les_getCheckpoint',
+			params: 1
+		}),
+	],
+	properties: 
+	[
+		new web3._extend.Property({
+			name: 'latestCheckpoint',
+			getter: 'les_latestCheckpoint'
+		}),
+		new web3._extend.Property({
+			name: 'checkpointContractAddress',
+			getter: 'les_getCheckpointContractAddress'
+		}),
+	]
+});
+`

les/api.go

@@ -34,6 +34,8 @@ var (
 	ErrMinCap               = errors.New("capacity too small")
 	ErrTotalCap             = errors.New("total capacity exceeded")
 	ErrUnknownBenchmarkType = errors.New("unknown benchmark type")
+	ErrNoCheckpoint         = errors.New("no local checkpoint provided")
+	ErrNotActivated         = errors.New("checkpoint registrar is not activated")
 
 	dropCapacityDelay = time.Second // delay applied to decreasing capacity changes
 )
@@ -470,3 +472,59 @@ func (api *PrivateLightServerAPI) Benchmark(setups []map[string]interface{}, pas
 	}
 	return result, nil
 }
+
+// PrivateLightAPI provides an API to access the LES light server or light client.
+type PrivateLightAPI struct {
+	backend *lesCommons
+	reg     *checkpointRegistrar
+}
+
+// NewPrivateLightAPI creates a new LES service API.
+func NewPrivateLightAPI(backend *lesCommons, reg *checkpointRegistrar) *PrivateLightAPI {
+	return &PrivateLightAPI{
+		backend: backend,
+		reg:     reg,
+	}
+}
+
+// LatestCheckpoint returns the latest local checkpoint package.
+//
+// The checkpoint package consists of 4 strings:
+//   result[0], hex encoded latest section index
+//   result[1], 32 bytes hex encoded latest section head hash
+//   result[2], 32 bytes hex encoded latest section canonical hash trie root hash
+//   result[3], 32 bytes hex encoded latest section bloom trie root hash
+func (api *PrivateLightAPI) LatestCheckpoint() ([4]string, error) {
+	var res [4]string
+	cp := api.backend.latestLocalCheckpoint()
+	if cp.Empty() {
+		return res, ErrNoCheckpoint
+	}
+	res[0] = hexutil.EncodeUint64(cp.SectionIndex)
+	res[1], res[2], res[3] = cp.SectionHead.Hex(), cp.CHTRoot.Hex(), cp.BloomRoot.Hex()
+	return res, nil
+}
+
+// GetLocalCheckpoint returns the specific local checkpoint package.
+//
+// The checkpoint package consists of 3 strings:
+//   result[0], 32 bytes hex encoded latest section head hash
+//   result[1], 32 bytes hex encoded latest section canonical hash trie root hash
+//   result[2], 32 bytes hex encoded latest section bloom trie root hash
+func (api *PrivateLightAPI) GetCheckpoint(index uint64) ([3]string, error) {
+	var res [3]string
+	cp := api.backend.getLocalCheckpoint(index)
+	if cp.Empty() {
+		return res, ErrNoCheckpoint
+	}
+	res[0], res[1], res[2] = cp.SectionHead.Hex(), cp.CHTRoot.Hex(), cp.BloomRoot.Hex()
+	return res, nil
+}
+
+// GetCheckpointContractAddress returns the contract contract address in hex format.
+func (api *PrivateLightAPI) GetCheckpointContractAddress() (string, error) {
+	if api.reg == nil {
+		return "", ErrNotActivated
+	}
+	return api.reg.config.ContractAddr.Hex(), nil
+}

les/backend.go

@@ -23,6 +23,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/accounts"
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/common/mclock"
@@ -43,14 +44,13 @@ import (
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/discv5"
 	"github.com/ethereum/go-ethereum/params"
-	rpc "github.com/ethereum/go-ethereum/rpc"
+	"github.com/ethereum/go-ethereum/rpc"
 )
 
 type LightEthereum struct {
 	lesCommons
 
 	odr         *LesOdr
-	relay       *LesTxRelay
 	chainConfig *params.ChainConfig
 	// Channel for shutting down the service
 	shutdownChan chan bool
@@ -62,6 +62,7 @@ type LightEthereum struct {
 	serverPool *serverPool
 	reqDist    *requestDistributor
 	retriever  *retrieveManager
+	relay      *lesTxRelay
 
 	bloomRequests chan chan *bloombits.Retrieval // Channel receiving bloom data retrieval requests
 	bloomIndexer  *core.ChainIndexer
@@ -116,7 +117,7 @@ func New(ctx *node.ServiceContext, config *eth.Config) (*LightEthereum, error) {
 	}
 	leth.serverPool = newServerPool(chainDb, quitSync, &leth.wg, trustedNodes)
 	leth.retriever = newRetrieveManager(peers, leth.reqDist, leth.serverPool)
-	leth.relay = NewLesTxRelay(peers, leth.retriever)
+	leth.relay = newLesTxRelay(peers, leth.retriever)
 
 	leth.odr = NewLesOdr(chainDb, light.DefaultClientIndexerConfig, leth.retriever)
 	leth.chtIndexer = light.NewChtIndexer(chainDb, leth.odr, params.CHTFrequency, params.HelperTrieConfirmations)
@@ -141,32 +142,6 @@ func New(ctx *node.ServiceContext, config *eth.Config) (*LightEthereum, error) {
 	}
 
 	leth.txPool = light.NewTxPool(leth.chainConfig, leth.blockchain, leth.relay)
-
-	if leth.protocolManager, err = NewProtocolManager(
-		leth.chainConfig,
-		light.DefaultClientIndexerConfig,
-		true,
-		config.NetworkId,
-		leth.eventMux,
-		leth.engine,
-		leth.peers,
-		leth.blockchain,
-		nil,
-		chainDb,
-		leth.odr,
-		leth.relay,
-		leth.serverPool,
-		quitSync,
-		&leth.wg,
-		config.ULC,
-		nil); err != nil {
-		return nil, err
-	}
-
-	if leth.protocolManager.isULCEnabled() {
-		log.Warn("Ultra light client is enabled", "trustedNodes", len(leth.protocolManager.ulc.trustedKeys), "minTrustedFraction", leth.protocolManager.ulc.minTrustedFraction)
-		leth.blockchain.DisableCheckFreq()
-	}
 	leth.ApiBackend = &LesApiBackend{ctx.ExtRPCEnabled(), leth, nil}
 
 	gpoParams := config.GPO
@@ -174,6 +149,15 @@ func New(ctx *node.ServiceContext, config *eth.Config) (*LightEthereum, error) {
 		gpoParams.Default = config.Miner.GasPrice
 	}
 	leth.ApiBackend.gpo = gasprice.NewOracle(leth.ApiBackend, gpoParams)
+
+	registrar := newCheckpointRegistrar(chainConfig.CheckpointContract, leth.getLocalCheckpoint)
+	if leth.protocolManager, err = NewProtocolManager(leth.chainConfig, light.DefaultClientIndexerConfig, config.ULC, true, config.NetworkId, leth.eventMux, leth.peers, leth.blockchain, nil, chainDb, leth.odr, leth.serverPool, registrar, quitSync, &leth.wg, nil); err != nil {
+		return nil, err
+	}
+	if leth.protocolManager.isULCEnabled() {
+		log.Warn("Ultra light client is enabled", "trustedNodes", len(leth.protocolManager.ulc.trustedKeys), "minTrustedFraction", leth.protocolManager.ulc.minTrustedFraction)
+		leth.blockchain.DisableCheckFreq()
+	}
 	return leth, nil
 }
 
@@ -234,6 +218,11 @@ func (s *LightEthereum) APIs() []rpc.API {
 			Version:   "1.0",
 			Service:   s.netRPCService,
 			Public:    true,
+		}, {
+			Namespace: "les",
+			Version:   "1.0",
+			Service:   NewPrivateLightAPI(&s.lesCommons, s.protocolManager.reg),
+			Public:    false,
 		},
 	}...)
 }
@@ -288,3 +277,12 @@ func (s *LightEthereum) Stop() error {
 
 	return nil
 }
+
+// SetClient sets the rpc client and binds the registrar contract.
+func (s *LightEthereum) SetContractBackend(backend bind.ContractBackend) {
+	// Short circuit if registrar is nil
+	if s.protocolManager.reg == nil {
+		return
+	}
+	s.protocolManager.reg.start(backend)
+}

les/commons.go

@@ -76,24 +76,6 @@ func (c *lesCommons) makeProtocols(versions []uint) []p2p.Protocol {
 
 // nodeInfo retrieves some protocol metadata about the running host node.
 func (c *lesCommons) nodeInfo() interface{} {
-	var cht params.TrustedCheckpoint
-	sections, _, _ := c.chtIndexer.Sections()
-	sections2, _, _ := c.bloomTrieIndexer.Sections()
-
-	if sections2 < sections {
-		sections = sections2
-	}
-	if sections > 0 {
-		sectionIndex := sections - 1
-		sectionHead := c.bloomTrieIndexer.SectionHead(sectionIndex)
-		cht = params.TrustedCheckpoint{
-			SectionIndex: sectionIndex,
-			SectionHead:  sectionHead,
-			CHTRoot:      light.GetChtRoot(c.chainDb, sectionIndex, sectionHead),
-			BloomRoot:    light.GetBloomTrieRoot(c.chainDb, sectionIndex, sectionHead),
-		}
-	}
-
 	chain := c.protocolManager.blockchain
 	head := chain.CurrentHeader()
 	hash := head.Hash()
@@ -103,6 +85,38 @@ func (c *lesCommons) nodeInfo() interface{} {
 		Genesis:    chain.Genesis().Hash(),
 		Config:     chain.Config(),
 		Head:       chain.CurrentHeader().Hash(),
-		CHT:        cht,
+		CHT:        c.latestLocalCheckpoint(),
+	}
+}
+
+// latestLocalCheckpoint finds the common stored section index and returns a set of
+// post-processed trie roots (CHT and BloomTrie) associated with
+// the appropriate section index and head hash as a local checkpoint package.
+func (c *lesCommons) latestLocalCheckpoint() params.TrustedCheckpoint {
+	sections, _, _ := c.chtIndexer.Sections()
+	sections2, _, _ := c.bloomTrieIndexer.Sections()
+	// Cap the section index if the two sections are not consistent.
+	if sections > sections2 {
+		sections = sections2
+	}
+	if sections == 0 {
+		// No checkpoint information can be provided.
+		return params.TrustedCheckpoint{}
+	}
+	return c.getLocalCheckpoint(sections - 1)
+}
+
+// getLocalCheckpoint returns a set of post-processed trie roots (CHT and BloomTrie)
+// associated with the appropriate head hash by specific section index.
+//
+// The returned checkpoint is only the checkpoint generated by the local indexers,
+// not the stable checkpoint registered in the registrar contract.
+func (c *lesCommons) getLocalCheckpoint(index uint64) params.TrustedCheckpoint {
+	sectionHead := c.chtIndexer.SectionHead(index)
+	return params.TrustedCheckpoint{
+		SectionIndex: index,
+		SectionHead:  sectionHead,
+		CHTRoot:      light.GetChtRoot(c.chainDb, index, sectionHead),
+		BloomRoot:    light.GetBloomTrieRoot(c.chainDb, index, sectionHead),
 	}
 }

les/handler.go

@@ -25,7 +25,6 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/consensus"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/core/state"
@@ -97,7 +96,7 @@ type ProtocolManager struct {
 	networkId uint64 // The identity of network.
 
 	txpool       txPool
-	txrelay      *LesTxRelay
+	txrelay      *lesTxRelay
 	blockchain   BlockChain
 	chainDb      ethdb.Database
 	odr          *LesOdr
@@ -111,6 +110,7 @@ type ProtocolManager struct {
 	fetcher      *lightFetcher
 	ulc          *ulc
 	peers        *peerSet
+	reg          *checkpointRegistrar // If reg == nil, it means the checkpoint registrar is not activated
 
 	// channels for fetcher, syncer, txsyncLoop
 	newPeerCh   chan *peer
@@ -127,23 +127,7 @@ type ProtocolManager struct {
 
 // NewProtocolManager returns a new ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
 // with the ethereum network.
-func NewProtocolManager(
+func NewProtocolManager(chainConfig *params.ChainConfig, indexerConfig *light.IndexerConfig, ulcConfig *eth.ULCConfig, client bool, networkId uint64, mux *event.TypeMux, peers *peerSet, blockchain BlockChain, txpool txPool, chainDb ethdb.Database, odr *LesOdr, serverPool *serverPool, registrar *checkpointRegistrar, quitSync chan struct{}, wg *sync.WaitGroup, synced func() bool) (*ProtocolManager, error) {
-	chainConfig *params.ChainConfig,
-	indexerConfig *light.IndexerConfig,
-	client bool,
-	networkId uint64,
-	mux *event.TypeMux,
-	engine consensus.Engine,
-	peers *peerSet,
-	blockchain BlockChain,
-	txpool txPool,
-	chainDb ethdb.Database,
-	odr *LesOdr,
-	txrelay *LesTxRelay,
-	serverPool *serverPool,
-	quitSync chan struct{},
-	wg *sync.WaitGroup,
-	ulcConfig *eth.ULCConfig, synced func() bool) (*ProtocolManager, error) {
 	// Create the protocol manager with the base fields
 	manager := &ProtocolManager{
 		client:      client,
@@ -155,8 +139,8 @@ func NewProtocolManager(
 		odr:         odr,
 		networkId:   networkId,
 		txpool:      txpool,
-		txrelay:     txrelay,
 		serverPool:  serverPool,
+		reg:         registrar,
 		peers:       peers,
 		newPeerCh:   make(chan *peer),
 		quitSync:    quitSync,

les/handler_test.go

@@ -258,7 +258,6 @@ func testGetCode(t *testing.T, protocol int) {
 
 	var codereqs []*CodeReq
 	var codes [][]byte
-
 	for i := uint64(0); i <= bc.CurrentBlock().NumberU64(); i++ {
 		header := bc.GetHeaderByNumber(i)
 		req := &CodeReq{
@@ -315,11 +314,10 @@ func testGetProofs(t *testing.T, protocol int) {
 	var proofreqs []ProofReq
 	proofsV2 := light.NewNodeSet()
 
-	accounts := []common.Address{testBankAddress, acc1Addr, acc2Addr, {}}
+	accounts := []common.Address{bankAddr, userAddr1, userAddr2, {}}
 	for i := uint64(0); i <= bc.CurrentBlock().NumberU64(); i++ {
 		header := bc.GetHeaderByNumber(i)
-		root := header.Root
+		trie, _ := trie.New(header.Root, trie.NewDatabase(server.db))
-		trie, _ := trie.New(root, trie.NewDatabase(server.db))
 
 		for _, acc := range accounts {
 			req := ProofReq{
@@ -432,14 +430,15 @@ func TestGetBloombitsProofs(t *testing.T) {
 }
 
 func TestTransactionStatusLes2(t *testing.T) {
-	db := rawdb.NewMemoryDatabase()
+	server, tearDown := newServerEnv(t, 0, 2, nil)
-	pm := newTestProtocolManagerMust(t, false, 0, nil, nil, nil, db, nil)
+	defer tearDown()
-	chain := pm.blockchain.(*core.BlockChain)
+
+	chain := server.pm.blockchain.(*core.BlockChain)
 	config := core.DefaultTxPoolConfig
 	config.Journal = ""
 	txpool := core.NewTxPool(config, params.TestChainConfig, chain)
-	pm.txpool = txpool
+	server.pm.txpool = txpool
-	peer, _ := newTestPeer(t, "peer", 2, pm, true, 0)
+	peer, _ := newTestPeer(t, "peer", 2, server.pm, true, 0)
 	defer peer.close()
 
 	var reqID uint64
@@ -447,13 +446,13 @@ func TestTransactionStatusLes2(t *testing.T) {
 	test := func(tx *types.Transaction, send bool, expStatus light.TxStatus) {
 		reqID++
 		if send {
-			cost := peer.GetRequestCost(SendTxV2Msg, 1)
+			cost := server.tPeer.GetRequestCost(SendTxV2Msg, 1)
-			sendRequest(peer.app, SendTxV2Msg, reqID, cost, types.Transactions{tx})
+			sendRequest(server.tPeer.app, SendTxV2Msg, reqID, cost, types.Transactions{tx})
 		} else {
-			cost := peer.GetRequestCost(GetTxStatusMsg, 1)
+			cost := server.tPeer.GetRequestCost(GetTxStatusMsg, 1)
-			sendRequest(peer.app, GetTxStatusMsg, reqID, cost, []common.Hash{tx.Hash()})
+			sendRequest(server.tPeer.app, GetTxStatusMsg, reqID, cost, []common.Hash{tx.Hash()})
 		}
-		if err := expectResponse(peer.app, TxStatusMsg, reqID, testBufLimit, []light.TxStatus{expStatus}); err != nil {
+		if err := expectResponse(server.tPeer.app, TxStatusMsg, reqID, testBufLimit, []light.TxStatus{expStatus}); err != nil {
 			t.Errorf("transaction status mismatch")
 		}
 	}
@@ -461,16 +460,16 @@ func TestTransactionStatusLes2(t *testing.T) {
 	signer := types.HomesteadSigner{}
 
 	// test error status by sending an underpriced transaction
-	tx0, _ := types.SignTx(types.NewTransaction(0, acc1Addr, big.NewInt(10000), params.TxGas, nil, nil), signer, testBankKey)
+	tx0, _ := types.SignTx(types.NewTransaction(0, userAddr1, big.NewInt(10000), params.TxGas, nil, nil), signer, bankKey)
 	test(tx0, true, light.TxStatus{Status: core.TxStatusUnknown, Error: core.ErrUnderpriced.Error()})
 
-	tx1, _ := types.SignTx(types.NewTransaction(0, acc1Addr, big.NewInt(10000), params.TxGas, big.NewInt(100000000000), nil), signer, testBankKey)
+	tx1, _ := types.SignTx(types.NewTransaction(0, userAddr1, big.NewInt(10000), params.TxGas, big.NewInt(100000000000), nil), signer, bankKey)
 	test(tx1, false, light.TxStatus{Status: core.TxStatusUnknown}) // query before sending, should be unknown
 	test(tx1, true, light.TxStatus{Status: core.TxStatusPending})  // send valid processable tx, should return pending
 	test(tx1, true, light.TxStatus{Status: core.TxStatusPending})  // adding it again should not return an error
 
-	tx2, _ := types.SignTx(types.NewTransaction(1, acc1Addr, big.NewInt(10000), params.TxGas, big.NewInt(100000000000), nil), signer, testBankKey)
+	tx2, _ := types.SignTx(types.NewTransaction(1, userAddr1, big.NewInt(10000), params.TxGas, big.NewInt(100000000000), nil), signer, bankKey)
-	tx3, _ := types.SignTx(types.NewTransaction(2, acc1Addr, big.NewInt(10000), params.TxGas, big.NewInt(100000000000), nil), signer, testBankKey)
+	tx3, _ := types.SignTx(types.NewTransaction(2, userAddr1, big.NewInt(10000), params.TxGas, big.NewInt(100000000000), nil), signer, bankKey)
 	// send transactions in the wrong order, tx3 should be queued
 	test(tx3, true, light.TxStatus{Status: core.TxStatusQueued})
 	test(tx2, true, light.TxStatus{Status: core.TxStatusPending})
@@ -478,7 +477,7 @@ func TestTransactionStatusLes2(t *testing.T) {
 	test(tx3, false, light.TxStatus{Status: core.TxStatusPending})
 
 	// generate and add a block with tx1 and tx2 included
-	gchain, _ := core.GenerateChain(params.TestChainConfig, chain.GetBlockByNumber(0), ethash.NewFaker(), db, 1, func(i int, block *core.BlockGen) {
+	gchain, _ := core.GenerateChain(params.TestChainConfig, chain.GetBlockByNumber(0), ethash.NewFaker(), server.db, 1, func(i int, block *core.BlockGen) {
 		block.AddTx(tx1)
 		block.AddTx(tx2)
 	})
@@ -497,12 +496,12 @@ func TestTransactionStatusLes2(t *testing.T) {
 	}
 
 	// check if their status is included now
-	block1hash := rawdb.ReadCanonicalHash(db, 1)
+	block1hash := rawdb.ReadCanonicalHash(server.db, 1)
 	test(tx1, false, light.TxStatus{Status: core.TxStatusIncluded, Lookup: &rawdb.LegacyTxLookupEntry{BlockHash: block1hash, BlockIndex: 1, Index: 0}})
 	test(tx2, false, light.TxStatus{Status: core.TxStatusIncluded, Lookup: &rawdb.LegacyTxLookupEntry{BlockHash: block1hash, BlockIndex: 1, Index: 1}})
 
 	// create a reorg that rolls them back
-	gchain, _ = core.GenerateChain(params.TestChainConfig, chain.GetBlockByNumber(0), ethash.NewFaker(), db, 2, func(i int, block *core.BlockGen) {})
+	gchain, _ = core.GenerateChain(params.TestChainConfig, chain.GetBlockByNumber(0), ethash.NewFaker(), server.db, 2, func(i int, block *core.BlockGen) {})
 	if _, err := chain.InsertChain(gchain); err != nil {
 		panic(err)
 	}
@@ -525,7 +524,7 @@ func TestStopResumeLes3(t *testing.T) {
 	db := rawdb.NewMemoryDatabase()
 	clock := &mclock.Simulated{}
 	testCost := testBufLimit / 10
-	pm, err := newTestProtocolManager(false, 0, nil, nil, nil, db, nil, testCost, clock)
+	pm, _, err := newTestProtocolManager(false, 0, nil, nil, nil, db, nil, testCost, clock)
 	if err != nil {
 		t.Fatalf("Failed to create protocol manager: %v", err)
 	}

les/helper_test.go

@@ -20,19 +20,22 @@
 package les
 
 import (
+	"context"
 	"crypto/rand"
 	"math/big"
 	"sync"
 	"testing"
 	"time"
 
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/accounts/abi/bind/backends"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/mclock"
 	"github.com/ethereum/go-ethereum/consensus/ethash"
+	"github.com/ethereum/go-ethereum/contracts/registrar/contract"
 	"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/eth"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -45,14 +48,14 @@ import (
 )
 
 var (
-	testBankKey, _  = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
+	bankKey, _ = crypto.GenerateKey()
-	testBankAddress = crypto.PubkeyToAddress(testBankKey.PublicKey)
+	bankAddr   = crypto.PubkeyToAddress(bankKey.PublicKey)
-	testBankFunds   = big.NewInt(1000000000000000000)
+	bankFunds  = big.NewInt(1000000000000000000)
 
-	acc1Key, _ = crypto.HexToECDSA("8a1f9a8f95be41cd7ccb6168179afb4504aefe388d1e14474d32c45c72ce7b7a")
+	userKey1, _ = crypto.GenerateKey()
-	acc2Key, _ = crypto.HexToECDSA("49a7b37aa6f6645917e7b807e9d1c00d4fa71f18343b0d4122a4d2df64dd6fee")
+	userKey2, _ = crypto.GenerateKey()
-	acc1Addr   = crypto.PubkeyToAddress(acc1Key.PublicKey)
+	userAddr1   = crypto.PubkeyToAddress(userKey1.PublicKey)
-	acc2Addr   = crypto.PubkeyToAddress(acc2Key.PublicKey)
+	userAddr2   = crypto.PubkeyToAddress(userKey2.PublicKey)
 
 	testContractCode         = common.Hex2Bytes("606060405260cc8060106000396000f360606040526000357c01000000000000000000000000000000000000000000000000000000009004806360cd2685146041578063c16431b914606b57603f565b005b6055600480803590602001909190505060a9565b6040518082815260200191505060405180910390f35b60886004808035906020019091908035906020019091905050608a565b005b80600060005083606481101560025790900160005b50819055505b5050565b6000600060005082606481101560025790900160005b5054905060c7565b91905056")
 	testContractAddr         common.Address
@@ -60,8 +63,21 @@ var (
 	testContractDeployed     = uint64(2)
 
 	testEventEmitterCode = common.Hex2Bytes("60606040523415600e57600080fd5b7f57050ab73f6b9ebdd9f76b8d4997793f48cf956e965ee070551b9ca0bb71584e60405160405180910390a160358060476000396000f3006060604052600080fd00a165627a7a723058203f727efcad8b5811f8cb1fc2620ce5e8c63570d697aef968172de296ea3994140029")
-	testEventEmitterAddr common.Address
 
+	// Checkpoint registrar relative
+	registrarAddr common.Address
+	signerKey, _  = crypto.GenerateKey()
+	signerAddr    = crypto.PubkeyToAddress(signerKey.PublicKey)
+)
+
+var (
+	// The block frequency for creating checkpoint(only used in test)
+	sectionSize = big.NewInt(512)
+
+	// The number of confirmations needed to generate a checkpoint(only used in test).
+	processConfirms = big.NewInt(4)
+
+	//
 	testBufLimit    = uint64(1000000)
 	testBufRecharge = uint64(1000)
 )
@@ -81,102 +97,140 @@ contract test {
 }
 */
 
-func testChainGen(i int, block *core.BlockGen) {
+// prepareTestchain pre-commits specified number customized blocks into chain.
-	signer := types.HomesteadSigner{}
+func prepareTestchain(n int, backend *backends.SimulatedBackend) {
-
+	var (
+		ctx    = context.Background()
+		signer = types.HomesteadSigner{}
+	)
+	for i := 0; i < n; i++ {
 		switch i {
 		case 0:
-		// In block 1, the test bank sends account #1 some ether.
+			// deploy checkpoint contract
-		tx, _ := types.SignTx(types.NewTransaction(block.TxNonce(testBankAddress), acc1Addr, big.NewInt(10000), params.TxGas, nil, nil), signer, testBankKey)
+			registrarAddr, _, _, _ = contract.DeployContract(bind.NewKeyedTransactor(bankKey), backend, []common.Address{signerAddr}, sectionSize, processConfirms, big.NewInt(1))
-		block.AddTx(tx)
+			// bankUser transfers some ether to user1
+			nonce, _ := backend.PendingNonceAt(ctx, bankAddr)
+			tx, _ := types.SignTx(types.NewTransaction(nonce, userAddr1, big.NewInt(10000), params.TxGas, nil, nil), signer, bankKey)
+			backend.SendTransaction(ctx, tx)
 		case 1:
-		// In block 2, the test bank sends some more ether to account #1.
+			bankNonce, _ := backend.PendingNonceAt(ctx, bankAddr)
-		// acc1Addr passes it on to account #2.
+			userNonce1, _ := backend.PendingNonceAt(ctx, userAddr1)
-		// acc1Addr creates a test contract.
-		// acc1Addr creates a test event.
-		nonce := block.TxNonce(acc1Addr)
 
-		tx1, _ := types.SignTx(types.NewTransaction(block.TxNonce(testBankAddress), acc1Addr, big.NewInt(1000), params.TxGas, nil, nil), signer, testBankKey)
+			// bankUser transfers more ether to user1
-		tx2, _ := types.SignTx(types.NewTransaction(nonce, acc2Addr, big.NewInt(1000), params.TxGas, nil, nil), signer, acc1Key)
+			tx1, _ := types.SignTx(types.NewTransaction(bankNonce, userAddr1, big.NewInt(1000), params.TxGas, nil, nil), signer, bankKey)
-		tx3, _ := types.SignTx(types.NewContractCreation(nonce+1, big.NewInt(0), 200000, big.NewInt(0), testContractCode), signer, acc1Key)
+			backend.SendTransaction(ctx, tx1)
-		testContractAddr = crypto.CreateAddress(acc1Addr, nonce+1)
+
-		tx4, _ := types.SignTx(types.NewContractCreation(nonce+2, big.NewInt(0), 200000, big.NewInt(0), testEventEmitterCode), signer, acc1Key)
+			// user1 relays ether to user2
-		testEventEmitterAddr = crypto.CreateAddress(acc1Addr, nonce+2)
+			tx2, _ := types.SignTx(types.NewTransaction(userNonce1, userAddr2, big.NewInt(1000), params.TxGas, nil, nil), signer, userKey1)
-		block.AddTx(tx1)
+			backend.SendTransaction(ctx, tx2)
-		block.AddTx(tx2)
+
-		block.AddTx(tx3)
+			// user1 deploys a test contract
-		block.AddTx(tx4)
+			tx3, _ := types.SignTx(types.NewContractCreation(userNonce1+1, big.NewInt(0), 200000, big.NewInt(0), testContractCode), signer, userKey1)
+			backend.SendTransaction(ctx, tx3)
+			testContractAddr = crypto.CreateAddress(userAddr1, userNonce1+1)
+
+			// user1 deploys a event contract
+			tx4, _ := types.SignTx(types.NewContractCreation(userNonce1+2, big.NewInt(0), 200000, big.NewInt(0), testEventEmitterCode), signer, userKey1)
+			backend.SendTransaction(ctx, tx4)
 		case 2:
-		// Block 3 is empty but was mined by account #2.
+			// bankUser transfer some ether to signer
-		block.SetCoinbase(acc2Addr)
+			bankNonce, _ := backend.PendingNonceAt(ctx, bankAddr)
-		block.SetExtra([]byte("yeehaw"))
+			tx1, _ := types.SignTx(types.NewTransaction(bankNonce, signerAddr, big.NewInt(1000000000), params.TxGas, nil, nil), signer, bankKey)
+			backend.SendTransaction(ctx, tx1)
+
+			// invoke test contract
 			data := common.Hex2Bytes("C16431B900000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000001")
-		tx, _ := types.SignTx(types.NewTransaction(block.TxNonce(testBankAddress), testContractAddr, big.NewInt(0), 100000, nil, data), signer, testBankKey)
+			tx2, _ := types.SignTx(types.NewTransaction(bankNonce+1, testContractAddr, big.NewInt(0), 100000, nil, data), signer, bankKey)
-		block.AddTx(tx)
+			backend.SendTransaction(ctx, tx2)
 		case 3:
-		// Block 4 includes blocks 2 and 3 as uncle headers (with modified extra data).
+			// invoke test contract
-		b2 := block.PrevBlock(1).Header()
+			bankNonce, _ := backend.PendingNonceAt(ctx, bankAddr)
-		b2.Extra = []byte("foo")
-		block.AddUncle(b2)
-		b3 := block.PrevBlock(2).Header()
-		b3.Extra = []byte("foo")
-		block.AddUncle(b3)
 			data := common.Hex2Bytes("C16431B900000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000002")
-		tx, _ := types.SignTx(types.NewTransaction(block.TxNonce(testBankAddress), testContractAddr, big.NewInt(0), 100000, nil, data), signer, testBankKey)
+			tx, _ := types.SignTx(types.NewTransaction(bankNonce, testContractAddr, big.NewInt(0), 100000, nil, data), signer, bankKey)
-		block.AddTx(tx)
+			backend.SendTransaction(ctx, tx)
+		}
+		backend.Commit()
 	}
 }
 
 // testIndexers creates a set of indexers with specified params for testing purpose.
-func testIndexers(db ethdb.Database, odr light.OdrBackend, iConfig *light.IndexerConfig) (*core.ChainIndexer, *core.ChainIndexer, *core.ChainIndexer) {
+func testIndexers(db ethdb.Database, odr light.OdrBackend, config *light.IndexerConfig) []*core.ChainIndexer {
-	chtIndexer := light.NewChtIndexer(db, odr, iConfig.ChtSize, iConfig.ChtConfirms)
+	var indexers [3]*core.ChainIndexer
-	bloomIndexer := eth.NewBloomIndexer(db, iConfig.BloomSize, iConfig.BloomConfirms)
+	indexers[0] = light.NewChtIndexer(db, odr, config.ChtSize, config.ChtConfirms)
-	bloomTrieIndexer := light.NewBloomTrieIndexer(db, odr, iConfig.BloomSize, iConfig.BloomTrieSize)
+	indexers[1] = eth.NewBloomIndexer(db, config.BloomSize, config.BloomConfirms)
-	bloomIndexer.AddChildIndexer(bloomTrieIndexer)
+	indexers[2] = light.NewBloomTrieIndexer(db, odr, config.BloomSize, config.BloomTrieSize)
-	return chtIndexer, bloomIndexer, bloomTrieIndexer
+	// make bloomTrieIndexer as a child indexer of bloom indexer.
+	indexers[1].AddChildIndexer(indexers[2])
+	return indexers[:]
 }
 
 // newTestProtocolManager creates a new protocol manager for testing purposes,
 // with the given number of blocks already known, potential notification
 // channels for different events and relative chain indexers array.
-func newTestProtocolManager(lightSync bool, blocks int, generator func(int, *core.BlockGen), odr *LesOdr, peers *peerSet, db ethdb.Database, ulcConfig *eth.ULCConfig, testCost uint64, clock mclock.Clock) (*ProtocolManager, error) {
+func newTestProtocolManager(lightSync bool, blocks int, odr *LesOdr, indexers []*core.ChainIndexer, peers *peerSet, db ethdb.Database, ulcConfig *eth.ULCConfig, testCost uint64, clock mclock.Clock) (*ProtocolManager, *backends.SimulatedBackend, error) {
 	var (
 		evmux  = new(event.TypeMux)
 		engine = ethash.NewFaker()
 		gspec  = core.Genesis{
-			Config: params.TestChainConfig,
+			Config: params.AllEthashProtocolChanges,
-			Alloc:  core.GenesisAlloc{testBankAddress: {Balance: testBankFunds}},
+			Alloc:  core.GenesisAlloc{bankAddr: {Balance: bankFunds}},
 		}
-		genesis = gspec.MustCommit(db)
-		chain   BlockChain
 		pool   txPool
+		chain  BlockChain
+		exitCh = make(chan struct{})
 	)
+	gspec.MustCommit(db)
 	if peers == nil {
 		peers = newPeerSet()
 	}
+	// create a simulation backend and pre-commit several customized block to the database.
+	simulation := backends.NewSimulatedBackend(db, gspec.Alloc, 100000000)
+	prepareTestchain(blocks, simulation)
 
+	// initialize empty chain for light client or pre-committed chain for server.
 	if lightSync {
 		chain, _ = light.NewLightChain(odr, gspec.Config, engine)
 	} else {
-		blockchain, _ := core.NewBlockChain(db, nil, gspec.Config, engine, vm.Config{}, nil)
+		chain = simulation.Blockchain()
-		gchain, _ := core.GenerateChain(gspec.Config, genesis, ethash.NewFaker(), db, blocks, generator)
+		pool = core.NewTxPool(core.DefaultTxPoolConfig, gspec.Config, simulation.Blockchain())
-		if _, err := blockchain.InsertChain(gchain); err != nil {
-			panic(err)
-		}
-		chain = blockchain
-		pool = core.NewTxPool(core.DefaultTxPoolConfig, gspec.Config, blockchain)
 	}
 
+	// Create contract registrar
 	indexConfig := light.TestServerIndexerConfig
 	if lightSync {
 		indexConfig = light.TestClientIndexerConfig
 	}
-	pm, err := NewProtocolManager(gspec.Config, indexConfig, lightSync, NetworkId, evmux, engine, peers, chain, pool, db, odr, nil, nil, make(chan struct{}), new(sync.WaitGroup), ulcConfig, func() bool { return true })
+	config := &params.CheckpointContractConfig{
-	if err != nil {
+		Name:         "test",
-		return nil, err
+		ContractAddr: crypto.CreateAddress(bankAddr, 0),
+		Signers:      []common.Address{signerAddr},
+		Threshold:    1,
 	}
+	var reg *checkpointRegistrar
+	if indexers != nil {
+		getLocal := func(index uint64) params.TrustedCheckpoint {
+			chtIndexer := indexers[0]
+			sectionHead := chtIndexer.SectionHead(index)
+			return params.TrustedCheckpoint{
+				SectionIndex: index,
+				SectionHead:  sectionHead,
+				CHTRoot:      light.GetChtRoot(db, index, sectionHead),
+				BloomRoot:    light.GetBloomTrieRoot(db, index, sectionHead),
+			}
+		}
+		reg = newCheckpointRegistrar(config, getLocal)
+	}
+	pm, err := NewProtocolManager(gspec.Config, indexConfig, ulcConfig, lightSync, NetworkId, evmux, peers, chain, pool, db, odr, nil, reg, exitCh, new(sync.WaitGroup), func() bool { return true })
+	if err != nil {
+		return nil, nil, err
+	}
+	// Registrar initialization could failed if checkpoint contract is not specified.
+	if pm.reg != nil {
+		pm.reg.start(simulation)
+	}
+	// Set up les server stuff.
 	if !lightSync {
-		srv := &LesServer{lesCommons: lesCommons{protocolManager: pm}}
+		srv := &LesServer{lesCommons: lesCommons{protocolManager: pm, chainDb: db}}
 		pm.server = srv
 		pm.servingQueue = newServingQueue(int64(time.Millisecond*10), 1, nil)
 		pm.servingQueue.setThreads(4)
@@ -189,19 +243,19 @@ func newTestProtocolManager(lightSync bool, blocks int, generator func(int, *cor
 		srv.fcManager = flowcontrol.NewClientManager(nil, clock)
 	}
 	pm.Start(1000)
-	return pm, nil
+	return pm, simulation, nil
 }
 
 // newTestProtocolManagerMust creates a new protocol manager for testing purposes,
-// with the given number of blocks already known, potential notification
+// with the given number of blocks already known, potential notification channels
-// channels for different events and relative chain indexers array. In case of an error, the constructor force-
+// for different events and relative chain indexers array. In case of an error, the
-// fails the test.
+// constructor force-fails the test.
-func newTestProtocolManagerMust(t *testing.T, lightSync bool, blocks int, generator func(int, *core.BlockGen), odr *LesOdr, peers *peerSet, db ethdb.Database, ulcConfig *eth.ULCConfig) *ProtocolManager {
+func newTestProtocolManagerMust(t *testing.T, lightSync bool, blocks int, odr *LesOdr, indexers []*core.ChainIndexer, peers *peerSet, db ethdb.Database, ulcConfig *eth.ULCConfig) (*ProtocolManager, *backends.SimulatedBackend) {
-	pm, err := newTestProtocolManager(lightSync, blocks, generator, odr, peers, db, ulcConfig, 0, &mclock.System{})
+	pm, backend, err := newTestProtocolManager(lightSync, blocks, odr, indexers, peers, db, ulcConfig, 0, &mclock.System{})
 	if err != nil {
 		t.Fatalf("Failed to create protocol manager: %v", err)
 	}
-	return pm
+	return pm, backend
 }
 
 // testPeer is a simulated peer to allow testing direct network calls.
@@ -329,6 +383,8 @@ type TestEntity struct {
 	tPeer   *testPeer
 	peers   *peerSet
 	pm      *ProtocolManager
+	backend *backends.SimulatedBackend
+
 	// Indexers
 	chtIndexer       *core.ChainIndexer
 	bloomIndexer     *core.ChainIndexer
@@ -338,11 +394,12 @@ type TestEntity struct {
 // newServerEnv creates a server testing environment with a connected test peer for testing purpose.
 func newServerEnv(t *testing.T, blocks int, protocol int, waitIndexers func(*core.ChainIndexer, *core.ChainIndexer, *core.ChainIndexer)) (*TestEntity, func()) {
 	db := rawdb.NewMemoryDatabase()
-	cIndexer, bIndexer, btIndexer := testIndexers(db, nil, light.TestServerIndexerConfig)
+	indexers := testIndexers(db, nil, light.TestServerIndexerConfig)
 
-	pm := newTestProtocolManagerMust(t, false, blocks, testChainGen, nil, nil, db, nil)
+	pm, b := newTestProtocolManagerMust(t, false, blocks, nil, indexers, nil, db, nil)
 	peer, _ := newTestPeer(t, "peer", protocol, pm, true, 0)
 
+	cIndexer, bIndexer, btIndexer := indexers[0], indexers[1], indexers[2]
 	cIndexer.Start(pm.blockchain.(*core.BlockChain))
 	bIndexer.Start(pm.blockchain.(*core.BlockChain))
 
@@ -355,6 +412,7 @@ func newServerEnv(t *testing.T, blocks int, protocol int, waitIndexers func(*cor
 			db:               db,
 			tPeer:            peer,
 			pm:               pm,
+			backend:          b,
 			chtIndexer:       cIndexer,
 			bloomIndexer:     bIndexer,
 			bloomTrieIndexer: btIndexer,
@@ -376,12 +434,16 @@ func newClientServerEnv(t *testing.T, blocks int, protocol int, waitIndexers fun
 	rm := newRetrieveManager(lPeers, dist, nil)
 	odr := NewLesOdr(ldb, light.TestClientIndexerConfig, rm)
 
-	cIndexer, bIndexer, btIndexer := testIndexers(db, nil, light.TestServerIndexerConfig)
+	indexers := testIndexers(db, nil, light.TestServerIndexerConfig)
-	lcIndexer, lbIndexer, lbtIndexer := testIndexers(ldb, odr, light.TestClientIndexerConfig)
+	lIndexers := testIndexers(ldb, odr, light.TestClientIndexerConfig)
+
+	cIndexer, bIndexer, btIndexer := indexers[0], indexers[1], indexers[2]
+	lcIndexer, lbIndexer, lbtIndexer := lIndexers[0], lIndexers[1], lIndexers[2]
+
 	odr.SetIndexers(lcIndexer, lbtIndexer, lbIndexer)
 
-	pm := newTestProtocolManagerMust(t, false, blocks, testChainGen, nil, peers, db, nil)
+	pm, b := newTestProtocolManagerMust(t, false, blocks, nil, indexers, peers, db, nil)
-	lpm := newTestProtocolManagerMust(t, true, 0, nil, odr, lPeers, ldb, nil)
+	lpm, lb := newTestProtocolManagerMust(t, true, 0, odr, lIndexers, lPeers, ldb, nil)
 
 	startIndexers := func(clientMode bool, pm *ProtocolManager) {
 		if clientMode {
@@ -421,6 +483,7 @@ func newClientServerEnv(t *testing.T, blocks int, protocol int, waitIndexers fun
 			pm:               pm,
 			rPeer:            peer,
 			peers:            peers,
+			backend:          b,
 			chtIndexer:       cIndexer,
 			bloomIndexer:     bIndexer,
 			bloomTrieIndexer: btIndexer,
@@ -429,6 +492,7 @@ func newClientServerEnv(t *testing.T, blocks int, protocol int, waitIndexers fun
 			pm:               lpm,
 			rPeer:            lPeer,
 			peers:            lPeers,
+			backend:          lb,
 			chtIndexer:       lcIndexer,
 			bloomIndexer:     lbIndexer,
 			bloomTrieIndexer: lbtIndexer,

les/odr_requests.go

@@ -166,11 +166,13 @@ func (r *ReceiptsRequest) Validate(db ethdb.Database, msg *Msg) error {
 	receipt := receipts[0]
 
 	// Retrieve our stored header and validate receipt content against it
-	header := rawdb.ReadHeader(db, r.Hash, r.Number)
+	if r.Header == nil {
-	if header == nil {
+		r.Header = rawdb.ReadHeader(db, r.Hash, r.Number)
+	}
+	if r.Header == nil {
 		return errHeaderUnavailable
 	}
-	if header.ReceiptHash != types.DeriveSha(receipt) {
+	if r.Header.ReceiptHash != types.DeriveSha(receipt) {
 		return errReceiptHashMismatch
 	}
 	// Validations passed, store and return
@@ -323,7 +325,11 @@ func (r *ChtRequest) CanSend(peer *peer) bool {
 	peer.lock.RLock()
 	defer peer.lock.RUnlock()
 
+	if r.Untrusted {
+		return peer.headInfo.Number >= r.BlockNum && peer.id == r.PeerId
+	} else {
 		return peer.headInfo.Number >= r.Config.ChtConfirms && r.ChtNum <= (peer.headInfo.Number-r.Config.ChtConfirms)/r.Config.ChtSize
+	}
 }
 
 // Request sends an ODR request to the LES network (implementation of LesOdrRequest)
@@ -364,6 +370,10 @@ func (r *ChtRequest) Validate(db ethdb.Database, msg *Msg) error {
 	}
 
 	// Verify the CHT
+	// Note: For untrusted CHT request, there is no proof response but
+	// header data.
+	var node light.ChtNode
+	if !r.Untrusted {
 		var encNumber [8]byte
 		binary.BigEndian.PutUint64(encNumber[:], r.BlockNum)
 
@@ -376,7 +386,6 @@ func (r *ChtRequest) Validate(db ethdb.Database, msg *Msg) error {
 			return errUselessNodes
 		}
 
-	var node light.ChtNode
 		if err := rlp.DecodeBytes(value, &node); err != nil {
 			return err
 		}
@@ -386,10 +395,12 @@ func (r *ChtRequest) Validate(db ethdb.Database, msg *Msg) error {
 		if r.BlockNum != header.Number.Uint64() {
 			return errCHTNumberMismatch
 		}
+	}
 	// Verifications passed, store and return
 	r.Header = header
 	r.Proof = nodeSet
-	r.Td = node.Td
+	r.Td = node.Td // For untrusted request, td here is nil, todo improve the les/2 protocol
+
 	return nil
 }
 

les/odr_test.go

@@ -78,7 +78,7 @@ func TestOdrAccountsLes2(t *testing.T) { testOdr(t, 2, 1, true, odrAccounts) }
 
 func odrAccounts(ctx context.Context, db ethdb.Database, config *params.ChainConfig, bc *core.BlockChain, lc *light.LightChain, bhash common.Hash) []byte {
 	dummyAddr := common.HexToAddress("1234567812345678123456781234567812345678")
-	acc := []common.Address{testBankAddress, acc1Addr, acc2Addr, dummyAddr}
+	acc := []common.Address{bankAddr, userAddr1, userAddr2, dummyAddr}
 
 	var (
 		res []byte
@@ -121,7 +121,7 @@ func odrContractCall(ctx context.Context, db ethdb.Database, config *params.Chai
 			statedb, err := state.New(header.Root, state.NewDatabase(db))
 
 			if err == nil {
-				from := statedb.GetOrNewStateObject(testBankAddress)
+				from := statedb.GetOrNewStateObject(bankAddr)
 				from.SetBalance(math.MaxBig256)
 
 				msg := callmsg{types.NewMessage(from.Address(), &testContractAddr, 0, new(big.Int), 100000, new(big.Int), data, false)}
@@ -137,8 +137,8 @@ func odrContractCall(ctx context.Context, db ethdb.Database, config *params.Chai
 		} else {
 			header := lc.GetHeaderByHash(bhash)
 			state := light.NewState(ctx, header, lc.Odr())
-			state.SetBalance(testBankAddress, math.MaxBig256)
+			state.SetBalance(bankAddr, math.MaxBig256)
-			msg := callmsg{types.NewMessage(testBankAddress, &testContractAddr, 0, new(big.Int), 100000, new(big.Int), data, false)}
+			msg := callmsg{types.NewMessage(bankAddr, &testContractAddr, 0, new(big.Int), 100000, new(big.Int), data, false)}
 			context := core.NewEVMContext(msg, header, lc, nil)
 			vmenv := vm.NewEVM(context, state, config, vm.Config{})
 			gp := new(core.GasPool).AddGas(math.MaxUint64)

les/peer.go

@@ -33,6 +33,7 @@ import (
 	"github.com/ethereum/go-ethereum/les/flowcontrol"
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/p2p"
+	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
@@ -77,6 +78,11 @@ type peer struct {
 
 	announceType uint64
 
+	// Checkpoint relative fields
+	advertisedCheckpoint params.TrustedCheckpoint
+	registeredHeight     uint64
+	isHardcode           bool // Indicator whether the checkpoint is hardcoded
+
 	id string
 
 	headInfo *announceData
@@ -565,6 +571,14 @@ func (p *peer) Handshake(td *big.Int, head common.Hash, headNum uint64, genesis
 		send = send.add("flowControl/MRC", costList)
 		p.fcCosts = costList.decode(ProtocolLengths[uint(p.version)])
 		p.fcParams = server.defParams
+
+		if server.protocolManager != nil && server.protocolManager.reg != nil && server.protocolManager.reg.isRunning() {
+			cp, height := server.protocolManager.reg.stableCheckpoint()
+			if cp != nil {
+				send = send.add("checkpoint/value", cp)
+				send = send.add("checkpoint/registerHeight", height)
+			}
+		}
 	} else {
 		//on client node
 		p.announceType = announceTypeSimple
@@ -648,20 +662,40 @@ func (p *peer) Handshake(td *big.Int, head common.Hash, headNum uint64, genesis
 			return errResp(ErrUselessPeer, "peer cannot serve requests")
 		}
 
-		var params flowcontrol.ServerParams
+		var sParams flowcontrol.ServerParams
-		if err := recv.get("flowControl/BL", &params.BufLimit); err != nil {
+		if err := recv.get("flowControl/BL", &sParams.BufLimit); err != nil {
 			return err
 		}
-		if err := recv.get("flowControl/MRR", &params.MinRecharge); err != nil {
+		if err := recv.get("flowControl/MRR", &sParams.MinRecharge); err != nil {
 			return err
 		}
 		var MRC RequestCostList
 		if err := recv.get("flowControl/MRC", &MRC); err != nil {
 			return err
 		}
-		p.fcParams = params
+		p.fcParams = sParams
-		p.fcServer = flowcontrol.NewServerNode(params, &mclock.System{})
+		p.fcServer = flowcontrol.NewServerNode(sParams, &mclock.System{})
 		p.fcCosts = MRC.decode(ProtocolLengths[uint(p.version)])
+
+		// Recap the checkpoint.
+		//
+		// The light client may be connected to several different versions of the server.
+		// (1) Old version server which can not provide stable checkpoint in the handshake packet.
+		//     => Use hardcoded checkpoint or empty checkpoint
+		// (2) New version server but simple checkpoint syncing is not enabled(e.g. mainnet, new testnet or private network)
+		//     => Use hardcoded checkpoint or empty checkpoint
+		// (3) New version server but the provided stable checkpoint is even lower than the hardcoded one.
+		//     => Use hardcoded checkpoint
+		// (4) New version server with valid and higher stable checkpoint
+		//     => Use provided checkpoint
+		hardcoded := params.TrustedCheckpoints[genesis]
+		if err := recv.get("checkpoint/value", &p.advertisedCheckpoint); hardcoded != nil &&
+			(err != nil || p.advertisedCheckpoint.SectionIndex < hardcoded.SectionIndex) {
+			p.advertisedCheckpoint = *hardcoded
+			p.isHardcode = true
+		}
+		recv.get("checkpoint/registerHeight", &p.registeredHeight)
+
 		if !p.isOnlyAnnounce {
 			for msgCode := range reqAvgTimeCost {
 				if p.fcCosts[msgCode] == nil {

les/registrar.go

@@ -0,0 +1,161 @@
+// Copyright 2016 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 les implements the Light Ethereum Subprotocol.
+package les
+
+import (
+	"encoding/binary"
+	"sync/atomic"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/contracts/registrar"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+// checkpointRegistrar is responsible for offering the latest stable checkpoint
+// which generated by local and announced by contract admins in the server
+// side and verifying advertised checkpoint during the checkpoint syncing
+// in the client side.
+type checkpointRegistrar struct {
+	config   *params.CheckpointContractConfig
+	contract *registrar.Registrar
+
+	// Whether the contract backend is set.
+	running int32
+
+	getLocal     func(uint64) params.TrustedCheckpoint // Function used to retrieve local checkpoint
+	syncDoneHook func()                                // Function used to notify that light syncing has completed.
+}
+
+// newCheckpointRegistrar returns a checkpoint registrar handler.
+func newCheckpointRegistrar(config *params.CheckpointContractConfig, getLocal func(uint64) params.TrustedCheckpoint) *checkpointRegistrar {
+	if config == nil {
+		log.Info("Checkpoint registrar is not enabled")
+		return nil
+	}
+	if config.ContractAddr == (common.Address{}) || uint64(len(config.Signers)) < config.Threshold {
+		log.Warn("Invalid checkpoint contract config")
+		return nil
+	}
+	log.Info("Setup checkpoint registrar", "contract", config.ContractAddr, "numsigner", len(config.Signers),
+		"threshold", config.Threshold)
+	return &checkpointRegistrar{
+		config:   config,
+		getLocal: getLocal,
+	}
+}
+
+// start binds the registrar contract and start listening to the
+// newCheckpointEvent for the server side.
+func (reg *checkpointRegistrar) start(backend bind.ContractBackend) {
+	contract, err := registrar.NewRegistrar(reg.config.ContractAddr, backend)
+	if err != nil {
+		log.Info("Registrar contract binding failed", "err", err)
+		return
+	}
+	if !atomic.CompareAndSwapInt32(&reg.running, 0, 1) {
+		log.Info("Already bound and listening to registrar contract")
+		return
+	}
+	reg.contract = contract
+}
+
+// isRunning returns an indicator whether the registrar is running.
+func (reg *checkpointRegistrar) isRunning() bool {
+	return atomic.LoadInt32(&reg.running) == 1
+}
+
+// stableCheckpoint returns the stable checkpoint which generated by local indexers
+// and announced by trusted signers.
+func (reg *checkpointRegistrar) stableCheckpoint() (*params.TrustedCheckpoint, uint64) {
+	latest, hash, height, err := reg.contract.Contract().GetLatestCheckpoint(nil)
+
+	// Short circuit if the checkpoint contract is empty.
+	if err != nil || latest == 0 && hash == [32]byte{} {
+		return nil, 0
+	}
+	local := reg.getLocal(latest)
+
+	// The following scenarios may occur:
+	//
+	// * local node is out of sync so that it doesn't have the
+	//   checkpoint which registered in the contract.
+	// * local checkpoint doesn't match with the registered one.
+	//
+	// In both cases, server won't send the **stable** checkpoint
+	// to the client(no worry, client can use hardcoded one instead).
+	if local.HashEqual(common.Hash(hash)) {
+		return &local, height.Uint64()
+	}
+	return nil, 0
+}
+
+// VerifySigner recovers the signer address according to the signature and
+// checks whether there are enough approves to finalize the checkpoint.
+func (reg *checkpointRegistrar) verifySigner(index uint64, hash [32]byte, signatures [][]byte) (bool, []common.Address) {
+	// Short circuit if the given signatures doesn't reach the threshold.
+	if len(signatures) < int(reg.config.Threshold) {
+		return false, nil
+	}
+	var (
+		signers []common.Address
+		checked = make(map[common.Address]struct{})
+	)
+	for i := 0; i < len(signatures); i += 1 {
+		if len(signatures[i]) != 65 {
+			continue
+		}
+		// EIP 191 style signatures
+		//
+		// Arguments when calculating hash to validate
+		// 1: byte(0x19) - the initial 0x19 byte
+		// 2: byte(0) - the version byte (data with intended validator)
+		// 3: this - the validator address
+		// --  Application specific data
+		// 4 : checkpoint section_index (uint64)
+		// 5 : checkpoint hash (bytes32)
+		//     hash = keccak256(checkpoint_index, section_head, cht_root, bloom_root)
+		buf := make([]byte, 8)
+		binary.BigEndian.PutUint64(buf, index)
+		data := append([]byte{0x19, 0x00}, append(reg.config.ContractAddr.Bytes(), append(buf, hash[:]...)...)...)
+		signatures[i][64] -= 27 // Transform V from 27/28 to 0/1 according to the yellow paper for verification.
+		pubkey, err := crypto.Ecrecover(crypto.Keccak256(data), signatures[i])
+		if err != nil {
+			return false, nil
+		}
+		var signer common.Address
+		copy(signer[:], crypto.Keccak256(pubkey[1:])[12:])
+		if _, exist := checked[signer]; exist {
+			continue
+		}
+		for _, s := range reg.config.Signers {
+			if s == signer {
+				signers = append(signers, signer)
+				checked[signer] = struct{}{}
+			}
+		}
+	}
+	threshold := reg.config.Threshold
+	if uint64(len(signers)) < threshold {
+		log.Warn("Not enough signatures to approve checkpoint", "given", len(signers), "want", threshold)
+		return false, nil
+	}
+	return true, signers
+}

les/request_test.go

@@ -28,7 +28,7 @@ import (
 	"github.com/ethereum/go-ethereum/light"
 )
 
-var testBankSecureTrieKey = secAddr(testBankAddress)
+var testBankSecureTrieKey = secAddr(bankAddr)
 
 func secAddr(addr common.Address) []byte {
 	return crypto.Keccak256(addr[:])

les/server.go

@@ -21,6 +21,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/mclock"
 	"github.com/ethereum/go-ethereum/core"
@@ -70,55 +71,27 @@ type LesServer struct {
 	priorityClientPool         *priorityClientPool
 }
 
-func NewLesServer(eth *eth.Ethereum, config *eth.Config) (*LesServer, error) {
+func NewLesServer(e *eth.Ethereum, config *eth.Config) (*LesServer, error) {
 	var csvLogger *csvlogger.Logger
 	if logFileName != "" {
 		csvLogger = csvlogger.NewLogger(logFileName, time.Second*10, "event, peerId")
 	}
-
-	quitSync := make(chan struct{})
-	pm, err := NewProtocolManager(
-		eth.BlockChain().Config(),
-		light.DefaultServerIndexerConfig,
-		false,
-		config.NetworkId,
-		eth.EventMux(),
-		eth.Engine(),
-		newPeerSet(),
-		eth.BlockChain(),
-		eth.TxPool(),
-		eth.ChainDb(),
-		nil,
-		nil,
-		nil,
-		quitSync,
-		new(sync.WaitGroup),
-		config.ULC, eth.Synced)
-	if err != nil {
-		return nil, err
-	}
-	if logProtocolHandler {
-		pm.logger = csvLogger
-	}
 	requestLogger := csvLogger
 	if !logRequestServing {
 		requestLogger = nil
 	}
-	pm.servingQueue = newServingQueue(int64(time.Millisecond*10), float64(config.LightServ)/100, requestLogger)
-
 	lesTopics := make([]discv5.Topic, len(AdvertiseProtocolVersions))
 	for i, pv := range AdvertiseProtocolVersions {
-		lesTopics[i] = lesTopic(eth.BlockChain().Genesis().Hash(), pv)
+		lesTopics[i] = lesTopic(e.BlockChain().Genesis().Hash(), pv)
 	}
-
+	quitSync := make(chan struct{})
 	srv := &LesServer{
 		lesCommons: lesCommons{
 			config:           config,
-			chainDb:          eth.ChainDb(),
 			iConfig:          light.DefaultServerIndexerConfig,
-			chtIndexer:       light.NewChtIndexer(eth.ChainDb(), nil, params.CHTFrequency, params.HelperTrieProcessConfirmations),
+			chainDb:          e.ChainDb(),
-			bloomTrieIndexer: light.NewBloomTrieIndexer(eth.ChainDb(), nil, params.BloomBitsBlocks, params.BloomTrieFrequency),
+			chtIndexer:       light.NewChtIndexer(e.ChainDb(), nil, params.CHTFrequency, params.HelperTrieProcessConfirmations),
-			protocolManager:  pm,
+			bloomTrieIndexer: light.NewBloomTrieIndexer(e.ChainDb(), nil, params.BloomBitsBlocks, params.BloomTrieFrequency),
 		},
 		quitSync:     quitSync,
 		lesTopics:    lesTopics,
@@ -126,10 +99,9 @@ func NewLesServer(eth *eth.Ethereum, config *eth.Config) (*LesServer, error) {
 		csvLogger:    csvLogger,
 		logTotalCap:  requestLogger.NewChannel("totalCapacity", 0.01),
 	}
-	srv.costTracker, srv.minCapacity = newCostTracker(eth.ChainDb(), config, requestLogger)
+	srv.costTracker, srv.minCapacity = newCostTracker(e.ChainDb(), config, requestLogger)
 
 	logger := log.New()
-	pm.server = srv
 	srv.thcNormal = config.LightServ * 4 / 100
 	if srv.thcNormal < 4 {
 		srv.thcNormal = 4
@@ -137,22 +109,26 @@ func NewLesServer(eth *eth.Ethereum, config *eth.Config) (*LesServer, error) {
 	srv.thcBlockProcessing = config.LightServ/100 + 1
 	srv.fcManager = flowcontrol.NewClientManager(nil, &mclock.System{})
 
-	chtSectionCount, _, _ := srv.chtIndexer.Sections()
+	checkpoint := srv.latestLocalCheckpoint()
-	if chtSectionCount != 0 {
+	if !checkpoint.Empty() {
-		chtLastSection := chtSectionCount - 1
+		logger.Info("Loaded latest checkpoint", "section", checkpoint.SectionIndex, "head", checkpoint.SectionHead,
-		chtSectionHead := srv.chtIndexer.SectionHead(chtLastSection)
+			"chtroot", checkpoint.CHTRoot, "bloomroot", checkpoint.BloomRoot)
-		chtRoot := light.GetChtRoot(pm.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)
-		logger.Info("Loaded bloom trie", "section", bloomTrieLastSection, "head", bloomTrieSectionHead, "root", bloomTrieRoot)
 	}
 
-	srv.chtIndexer.Start(eth.BlockChain())
+	srv.chtIndexer.Start(e.BlockChain())
+
+	registrar := newCheckpointRegistrar(e.BlockChain().Config().CheckpointContract, srv.getLocalCheckpoint)
+	pm, err := NewProtocolManager(e.BlockChain().Config(), light.DefaultServerIndexerConfig, config.ULC, false, config.NetworkId, e.EventMux(), newPeerSet(), e.BlockChain(), e.TxPool(), e.ChainDb(), nil, nil, registrar, quitSync, new(sync.WaitGroup), e.Synced)
+	if err != nil {
+		return nil, err
+	}
+	srv.protocolManager = pm
+	if logProtocolHandler {
+		pm.logger = csvLogger
+	}
+	pm.servingQueue = newServingQueue(int64(time.Millisecond*10), float64(config.LightServ)/100, requestLogger)
+	pm.server = srv
+
 	return srv, nil
 }
 
@@ -164,6 +140,12 @@ func (s *LesServer) APIs() []rpc.API {
 			Service:   NewPrivateLightServerAPI(s),
 			Public:    false,
 		},
+		{
+			Namespace: "les",
+			Version:   "1.0",
+			Service:   NewPrivateLightAPI(&s.lesCommons, s.protocolManager.reg),
+			Public:    false,
+		},
 	}
 }
 
@@ -288,6 +270,13 @@ func (s *LesServer) SetBloomBitsIndexer(bloomIndexer *core.ChainIndexer) {
 	bloomIndexer.AddChildIndexer(s.bloomTrieIndexer)
 }
 
+// SetClient sets the rpc client and starts running checkpoint contract if it is not yet watched.
+func (s *LesServer) SetContractBackend(backend bind.ContractBackend) {
+	if s.protocolManager.reg != nil {
+		s.protocolManager.reg.start(backend)
+	}
+}
+
 // Stop stops the LES service
 func (s *LesServer) Stop() {
 	s.fcManager.Stop()

les/sync.go

@@ -18,11 +18,30 @@ package les
 
 import (
 	"context"
+	"errors"
 	"time"
 
+	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/eth/downloader"
 	"github.com/ethereum/go-ethereum/light"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+var errInvalidCheckpoint = errors.New("invalid advertised checkpoint")
+
+const (
+	// lightSync starts syncing from the current highest block.
+	// If the chain is empty, syncing the entire header chain.
+	lightSync = iota
+
+	// legacyCheckpointSync starts syncing from a hardcoded checkpoint.
+	legacyCheckpointSync
+
+	// checkpointSync starts syncing from a checkpoint signed by trusted
+	// signer or hardcoded checkpoint for compatibility.
+	checkpointSync
 )
 
 // syncer is responsible for periodically synchronising with the network, both
@@ -54,26 +73,125 @@ func (pm *ProtocolManager) syncer() {
 	}
 }
 
-func (pm *ProtocolManager) needToSync(peerHead blockInfo) bool {
+// validateCheckpoint verifies the advertised checkpoint by peer is valid or not.
-	head := pm.blockchain.CurrentHeader()
+//
-	currentTd := rawdb.ReadTd(pm.chainDb, head.Hash(), head.Number.Uint64())
+// Each network has several hard-coded checkpoint signer addresses. Only the
-	return currentTd != nil && peerHead.Td.Cmp(currentTd) > 0
+// checkpoint issued by the specified signer is considered valid.
+//
+// In addition to the checkpoint registered in the registrar contract, there are
+// several legacy hardcoded checkpoints in our codebase. These checkpoints are
+// also considered as valid.
+func (pm *ProtocolManager) validateCheckpoint(peer *peer) error {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
+	defer cancel()
+
+	// Fetch the block header corresponding to the checkpoint registration.
+	cp := peer.advertisedCheckpoint
+	header, err := light.GetUntrustedHeaderByNumber(ctx, pm.odr, peer.registeredHeight, peer.id)
+	if err != nil {
+		return err
+	}
+	// Fetch block logs associated with the block header.
+	logs, err := light.GetUntrustedBlockLogs(ctx, pm.odr, header)
+	if err != nil {
+		return err
+	}
+	events := pm.reg.contract.LookupCheckpointEvent(logs, cp.SectionIndex, cp.Hash())
+	if len(events) == 0 {
+		return errInvalidCheckpoint
+	}
+	var (
+		index      = events[0].Index
+		hash       = events[0].CheckpointHash
+		signatures [][]byte
+	)
+	for _, event := range events {
+		signatures = append(signatures, append(event.R[:], append(event.S[:], event.V)...))
+	}
+	valid, signers := pm.reg.verifySigner(index, hash, signatures)
+	if !valid {
+		return errInvalidCheckpoint
+	}
+	log.Debug("Verify advertised checkpoint successfully", "peer", peer.id, "signernum", len(signers))
+	return nil
 }
 
-// synchronise tries to sync up our local block chain with a remote peer.
+// synchronise tries to sync up our local chain with a remote peer.
 func (pm *ProtocolManager) synchronise(peer *peer) {
-	// Short circuit if no peers are available
+	// Short circuit if the peer is nil.
 	if peer == nil {
 		return
 	}
-
 	// Make sure the peer's TD is higher than our own.
-	if !pm.needToSync(peer.headBlockInfo()) {
+	latest := pm.blockchain.CurrentHeader()
+	currentTd := rawdb.ReadTd(pm.chainDb, latest.Hash(), latest.Number.Uint64())
+	if currentTd != nil && peer.headBlockInfo().Td.Cmp(currentTd) < 0 {
 		return
 	}
+	// Determine whether we should run checkpoint syncing or normal light syncing.
+	//
+	// Here has four situations that we will disable the checkpoint syncing:
+	//
+	// 1. The checkpoint is empty
+	// 2. The latest head block of the local chain is above the checkpoint.
+	// 3. The checkpoint is hardcoded(recap with local hardcoded checkpoint)
+	// 4. For some networks the checkpoint syncing is not activated.
+	cp := &peer.advertisedCheckpoint
+	mode := checkpointSync
+	switch {
+	case cp.Empty():
+		mode = lightSync
+		log.Debug("Disable checkpoint syncing", "reason", "empty checkpoint")
+	case latest.Number.Uint64() >= (cp.SectionIndex+1)*pm.iConfig.ChtSize-1:
+		mode = lightSync
+		log.Debug("Disable checkpoint syncing", "reason", "local chain beyonds the checkpoint")
+	case peer.isHardcode:
+		mode = legacyCheckpointSync
+		log.Debug("Disable checkpoint syncing", "reason", "checkpoint is hardcoded")
+	case pm.reg == nil || !pm.reg.isRunning():
+		mode = legacyCheckpointSync
+		log.Debug("Disable checkpoint syncing", "reason", "checkpoint syncing is not activated")
+	}
+	// Notify testing framework if syncing has completed(for testing purpose).
+	defer func() {
+		if pm.reg != nil && pm.reg.syncDoneHook != nil {
+			pm.reg.syncDoneHook()
+		}
+	}()
+	start := time.Now()
+	if mode == checkpointSync || mode == legacyCheckpointSync {
+		// Validate the advertised checkpoint
+		if mode == legacyCheckpointSync {
+			cp = params.TrustedCheckpoints[pm.blockchain.Genesis().Hash()]
+		} else if mode == checkpointSync {
+			if err := pm.validateCheckpoint(peer); err != nil {
+				log.Debug("Failed to validate checkpoint", "reason", err)
+				pm.removePeer(peer.id)
+				return
+			}
+			pm.blockchain.(*light.LightChain).AddTrustedCheckpoint(cp)
+		}
+		log.Debug("Checkpoint syncing start", "peer", peer.id, "checkpoint", cp.SectionIndex)
 
+		// Fetch the start point block header.
+		//
+		// For the ethash consensus engine, the start header is the block header
+		// of the checkpoint.
+		//
+		// For the clique consensus engine, the start header is the block header
+		// of the latest epoch covered by checkpoint.
 		ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
 		defer cancel()
-	pm.blockchain.(*light.LightChain).SyncCht(ctx)
+		if !cp.Empty() && !pm.blockchain.(*light.LightChain).SyncCheckpoint(ctx, cp) {
-	pm.downloader.Synchronise(peer.id, peer.Head(), peer.Td(), downloader.LightSync)
+			log.Debug("Sync checkpoint failed")
+			pm.removePeer(peer.id)
+			return
+		}
+	}
+	// Fetch the remaining block headers based on the current chain header.
+	if err := pm.downloader.Synchronise(peer.id, peer.Head(), peer.Td(), downloader.LightSync); err != nil {
+		log.Debug("Synchronise failed", "reason", err)
+		return
+	}
+	log.Debug("Synchronise finished", "elapsed", common.PrettyDuration(time.Since(start)))
 }

les/sync_test.go

@@ -0,0 +1,112 @@
+// Copyright 2018 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 les
+
+import (
+	"errors"
+	"math/big"
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/light"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+func TestCheckpointSyncingLes2(t *testing.T) { testCheckpointSyncing(t, 2) }
+
+func testCheckpointSyncing(t *testing.T, protocol int) {
+	config := light.TestServerIndexerConfig
+
+	waitIndexers := func(cIndexer, bIndexer, btIndexer *core.ChainIndexer) {
+		for {
+			cs, _, _ := cIndexer.Sections()
+			bts, _, _ := btIndexer.Sections()
+			if cs >= 1 && bts >= 1 {
+				break
+			}
+			time.Sleep(10 * time.Millisecond)
+		}
+	}
+	// Generate 512+4 blocks (totally 1 CHT sections)
+	server, client, tearDown := newClientServerEnv(t, int(config.ChtSize+config.ChtConfirms), protocol, waitIndexers, false)
+	defer tearDown()
+
+	// Register checkpoint 0 into the contract at block (512+4)+1
+	s, _, head := server.chtIndexer.Sections()
+	chtRoot := light.GetChtRoot(server.db, s-1, head)
+	btRoot := light.GetBloomTrieRoot(server.db, s-1, head)
+
+	cp := &params.TrustedCheckpoint{
+		SectionIndex: 0,
+		SectionHead:  head,
+		CHTRoot:      chtRoot,
+		BloomRoot:    btRoot,
+	}
+	header := server.backend.Blockchain().CurrentHeader()
+
+	data := append([]byte{0x19, 0x00}, append(registrarAddr.Bytes(), append([]byte{0, 0, 0, 0, 0, 0, 0, 0}, cp.Hash().Bytes()...)...)...)
+	sig, _ := crypto.Sign(crypto.Keccak256(data), signerKey)
+	sig[64] += 27 // Transform V from 0/1 to 27/28 according to the yellow paper
+	if _, err := server.pm.reg.contract.RegisterCheckpoint(signerKey, cp.SectionIndex, cp.Hash().Bytes(), new(big.Int).Sub(header.Number, big.NewInt(1)), header.ParentHash, [][]byte{sig}); err != nil {
+		t.Error("register checkpoint failed", err)
+	}
+	server.backend.Commit()
+	server.backend.InsertEmptyBlocks(1)
+
+	// Wait for the checkpoint registration
+	for {
+		_, hash, _, err := server.pm.reg.contract.Contract().GetLatestCheckpoint(nil)
+		if err != nil || hash == [32]byte{} {
+			time.Sleep(100 * time.Millisecond)
+			continue
+		}
+		break
+	}
+
+	done := make(chan error)
+	client.pm.reg.syncDoneHook = func() {
+		header := client.pm.blockchain.CurrentHeader()
+		if header.Number.Uint64() == config.ChtSize+config.ChtConfirms+2 {
+			done <- nil
+		} else {
+			done <- errors.New("blockchain mismatch")
+		}
+	}
+
+	// Create connected peer pair.
+	peer, err1, lPeer, err2 := newTestPeerPair("peer", protocol, server.pm, client.pm)
+	select {
+	case <-time.After(time.Millisecond * 100):
+	case err := <-err1:
+		t.Fatalf("peer 1 handshake error: %v", err)
+	case err := <-err2:
+		t.Fatalf("peer 2 handshake error: %v", err)
+	}
+	server.rPeer, client.rPeer = peer, lPeer
+
+	select {
+	case err := <-done:
+		if err != nil {
+			t.Error("sync failed", err)
+		}
+		return
+	case <-time.NewTimer(10 * time.Second).C:
+		t.Error("checkpoint syncing timeout")
+	}
+}

les/txrelay.go

@@ -30,7 +30,7 @@ type ltrInfo struct {
 	sentTo map[*peer]struct{}
 }
 
-type LesTxRelay struct {
+type lesTxRelay struct {
 	txSent       map[common.Hash]*ltrInfo
 	txPending    map[common.Hash]struct{}
 	ps           *peerSet
@@ -42,8 +42,8 @@ type LesTxRelay struct {
 	retriever *retrieveManager
 }
 
-func NewLesTxRelay(ps *peerSet, retriever *retrieveManager) *LesTxRelay {
+func newLesTxRelay(ps *peerSet, retriever *retrieveManager) *lesTxRelay {
-	r := &LesTxRelay{
+	r := &lesTxRelay{
 		txSent:    make(map[common.Hash]*ltrInfo),
 		txPending: make(map[common.Hash]struct{}),
 		ps:        ps,
@@ -54,18 +54,18 @@ func NewLesTxRelay(ps *peerSet, retriever *retrieveManager) *LesTxRelay {
 	return r
 }
 
-func (self *LesTxRelay) Stop() {
+func (self *lesTxRelay) Stop() {
 	close(self.stop)
 }
 
-func (self *LesTxRelay) registerPeer(p *peer) {
+func (self *lesTxRelay) registerPeer(p *peer) {
 	self.lock.Lock()
 	defer self.lock.Unlock()
 
 	self.peerList = self.ps.AllPeers()
 }
 
-func (self *LesTxRelay) unregisterPeer(p *peer) {
+func (self *lesTxRelay) unregisterPeer(p *peer) {
 	self.lock.Lock()
 	defer self.lock.Unlock()
 
@@ -74,7 +74,7 @@ func (self *LesTxRelay) unregisterPeer(p *peer) {
 
 // send sends a list of transactions to at most a given number of peers at
 // once, never resending any particular transaction to the same peer twice
-func (self *LesTxRelay) send(txs types.Transactions, count int) {
+func (self *lesTxRelay) send(txs types.Transactions, count int) {
 	sendTo := make(map[*peer]types.Transactions)
 
 	self.peerStartPos++ // rotate the starting position of the peer list
@@ -143,14 +143,14 @@ func (self *LesTxRelay) send(txs types.Transactions, count int) {
 	}
 }
 
-func (self *LesTxRelay) Send(txs types.Transactions) {
+func (self *lesTxRelay) Send(txs types.Transactions) {
 	self.lock.Lock()
 	defer self.lock.Unlock()
 
 	self.send(txs, 3)
 }
 
-func (self *LesTxRelay) NewHead(head common.Hash, mined []common.Hash, rollback []common.Hash) {
+func (self *lesTxRelay) NewHead(head common.Hash, mined []common.Hash, rollback []common.Hash) {
 	self.lock.Lock()
 	defer self.lock.Unlock()
 
@@ -173,7 +173,7 @@ func (self *LesTxRelay) NewHead(head common.Hash, mined []common.Hash, rollback
 	}
 }
 
-func (self *LesTxRelay) Discard(hashes []common.Hash) {
+func (self *lesTxRelay) Discard(hashes []common.Hash) {
 	self.lock.Lock()
 	defer self.lock.Unlock()
 

les/ulc_test.go

@@ -26,7 +26,6 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common/mclock"
-	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/eth"
@@ -36,7 +35,7 @@ import (
 )
 
 func TestULCSyncWithOnePeer(t *testing.T) {
-	f := newFullPeerPair(t, 1, 4, testChainGen)
+	f := newFullPeerPair(t, 1, 4)
 	ulcConfig := &eth.ULCConfig{
 		MinTrustedFraction: 100,
 		TrustedServers:     []string{f.Node.String()},
@@ -63,7 +62,7 @@ func TestULCSyncWithOnePeer(t *testing.T) {
 }
 
 func TestULCReceiveAnnounce(t *testing.T) {
-	f := newFullPeerPair(t, 1, 4, testChainGen)
+	f := newFullPeerPair(t, 1, 4)
 	ulcConfig := &eth.ULCConfig{
 		MinTrustedFraction: 100,
 		TrustedServers:     []string{f.Node.String()},
@@ -100,8 +99,8 @@ func TestULCReceiveAnnounce(t *testing.T) {
 }
 
 func TestULCShouldNotSyncWithTwoPeersOneHaveEmptyChain(t *testing.T) {
-	f1 := newFullPeerPair(t, 1, 4, testChainGen)
+	f1 := newFullPeerPair(t, 1, 4)
-	f2 := newFullPeerPair(t, 2, 0, nil)
+	f2 := newFullPeerPair(t, 2, 0)
 	ulcConf := &ulc{minTrustedFraction: 100, trustedKeys: make(map[string]struct{})}
 	ulcConf.trustedKeys[f1.Node.ID().String()] = struct{}{}
 	ulcConf.trustedKeys[f2.Node.ID().String()] = struct{}{}
@@ -131,9 +130,9 @@ func TestULCShouldNotSyncWithTwoPeersOneHaveEmptyChain(t *testing.T) {
 }
 
 func TestULCShouldNotSyncWithThreePeersOneHaveEmptyChain(t *testing.T) {
-	f1 := newFullPeerPair(t, 1, 3, testChainGen)
+	f1 := newFullPeerPair(t, 1, 3)
-	f2 := newFullPeerPair(t, 2, 4, testChainGen)
+	f2 := newFullPeerPair(t, 2, 4)
-	f3 := newFullPeerPair(t, 3, 0, nil)
+	f3 := newFullPeerPair(t, 3, 0)
 
 	ulcConfig := &eth.ULCConfig{
 		MinTrustedFraction: 60,
@@ -211,10 +210,10 @@ func connectPeers(full, light pairPeer, version int) (*peer, *peer, error) {
 }
 
 // newFullPeerPair creates node with full sync mode
-func newFullPeerPair(t *testing.T, index int, numberOfblocks int, chainGen func(int, *core.BlockGen)) pairPeer {
+func newFullPeerPair(t *testing.T, index int, numberOfblocks int) pairPeer {
 	db := rawdb.NewMemoryDatabase()
 
-	pmFull := newTestProtocolManagerMust(t, false, numberOfblocks, chainGen, nil, nil, db, nil)
+	pmFull, _ := newTestProtocolManagerMust(t, false, numberOfblocks, nil, nil, nil, db, nil)
 
 	peerPairFull := pairPeer{
 		Name: "full node",
@@ -238,7 +237,7 @@ func newLightPeer(t *testing.T, ulcConfig *eth.ULCConfig) pairPeer {
 
 	odr := NewLesOdr(ldb, light.DefaultClientIndexerConfig, rm)
 
-	pmLight := newTestProtocolManagerMust(t, true, 0, nil, odr, peers, ldb, ulcConfig)
+	pmLight, _ := newTestProtocolManagerMust(t, true, 0, odr, nil, peers, ldb, ulcConfig)
 	peerPairLight := pairPeer{
 		Name: "ulc node",
 		PM:   pmLight,

light/lightchain.go

@@ -102,7 +102,7 @@ func NewLightChain(odr OdrBackend, config *params.ChainConfig, engine consensus.
 		return nil, core.ErrNoGenesis
 	}
 	if cp, ok := params.TrustedCheckpoints[bc.genesisBlock.Hash()]; ok {
-		bc.addTrustedCheckpoint(cp)
+		bc.AddTrustedCheckpoint(cp)
 	}
 	if err := bc.loadLastState(); err != nil {
 		return nil, err
@@ -118,8 +118,8 @@ func NewLightChain(odr OdrBackend, config *params.ChainConfig, engine consensus.
 	return bc, nil
 }
 
-// addTrustedCheckpoint adds a trusted checkpoint to the blockchain
+// AddTrustedCheckpoint adds a trusted checkpoint to the blockchain
-func (lc *LightChain) addTrustedCheckpoint(cp *params.TrustedCheckpoint) {
+func (lc *LightChain) AddTrustedCheckpoint(cp *params.TrustedCheckpoint) {
 	if lc.odr.ChtIndexer() != nil {
 		StoreChtRoot(lc.chainDb, cp.SectionIndex, cp.SectionHead, cp.CHTRoot)
 		lc.odr.ChtIndexer().AddCheckpoint(cp.SectionIndex, cp.SectionHead)
@@ -462,21 +462,21 @@ func (lc *LightChain) GetHeaderByNumberOdr(ctx context.Context, number uint64) (
 // Config retrieves the header chain's chain configuration.
 func (lc *LightChain) Config() *params.ChainConfig { return lc.hc.Config() }
 
-func (lc *LightChain) SyncCht(ctx context.Context) bool {
+// SyncCheckpoint fetches the checkpoint point block header according to
-	// If we don't have a CHT indexer, abort
+// the checkpoint provided by the remote peer.
-	if lc.odr.ChtIndexer() == nil {
+//
-		return false
+// Note if we are running the clique, fetches the last epoch snapshot header
-	}
+// which covered by checkpoint.
-	// Ensure the remote CHT head is ahead of us
+func (lc *LightChain) SyncCheckpoint(ctx context.Context, checkpoint *params.TrustedCheckpoint) bool {
+	// Ensure the remote checkpoint head is ahead of us
 	head := lc.CurrentHeader().Number.Uint64()
-	sections, _, _ := lc.odr.ChtIndexer().Sections()
 
-	latest := sections*lc.indexerConfig.ChtSize - 1
+	latest := (checkpoint.SectionIndex+1)*lc.indexerConfig.ChtSize - 1
 	if clique := lc.hc.Config().Clique; clique != nil {
 		latest -= latest % clique.Epoch // epoch snapshot for clique
 	}
 	if head >= latest {
-		return false
+		return true
 	}
 	// Retrieve the latest useful header and update to it
 	if header, err := GetHeaderByNumber(ctx, lc.odr, latest); header != nil && err == nil {

light/odr.go

@@ -122,19 +122,25 @@ func (req *BlockRequest) StoreResult(db ethdb.Database) {
 // ReceiptsRequest is the ODR request type for retrieving block bodies
 type ReceiptsRequest struct {
 	OdrRequest
+	Untrusted bool // Indicator whether the result retrieved is trusted or not
 	Hash      common.Hash
 	Number    uint64
+	Header    *types.Header
 	Receipts  types.Receipts
 }
 
 // StoreResult stores the retrieved data in local database
 func (req *ReceiptsRequest) StoreResult(db ethdb.Database) {
+	if !req.Untrusted {
 		rawdb.WriteReceipts(db, req.Hash, req.Number, req.Receipts)
+	}
 }
 
 // ChtRequest is the ODR request type for state/storage trie entries
 type ChtRequest struct {
 	OdrRequest
+	Untrusted        bool   // Indicator whether the result retrieved is trusted or not
+	PeerId           string // The specified peer id from which to retrieve data.
 	Config           *IndexerConfig
 	ChtNum, BlockNum uint64
 	ChtRoot          common.Hash
@@ -147,9 +153,11 @@ type ChtRequest struct {
 func (req *ChtRequest) StoreResult(db ethdb.Database) {
 	hash, num := req.Header.Hash(), req.Header.Number.Uint64()
 
+	if !req.Untrusted {
 		rawdb.WriteHeader(db, req.Header)
 		rawdb.WriteTd(db, hash, num, req.Td)
 		rawdb.WriteCanonicalHash(db, hash, num)
+	}
 }
 
 // BloomRequest is the ODR request type for retrieving bloom filters from a CHT structure

light/odr_util.go

@@ -69,6 +69,16 @@ func GetHeaderByNumber(ctx context.Context, odr OdrBackend, number uint64) (*typ
 	return r.Header, nil
 }
 
+// GetUntrustedHeaderByNumber fetches specified block header without correctness checking.
+// Note this function should only be used in light client checkpoint syncing.
+func GetUntrustedHeaderByNumber(ctx context.Context, odr OdrBackend, number uint64, peerId string) (*types.Header, error) {
+	r := &ChtRequest{BlockNum: number, ChtNum: number / odr.IndexerConfig().ChtSize, Untrusted: true, PeerId: peerId, Config: odr.IndexerConfig()}
+	if err := odr.Retrieve(ctx, r); err != nil {
+		return nil, err
+	}
+	return r.Header, nil
+}
+
 func GetCanonicalHash(ctx context.Context, odr OdrBackend, number uint64) (common.Hash, error) {
 	hash := rawdb.ReadCanonicalHash(odr.Database(), number)
 	if (hash != common.Hash{}) {
@@ -169,6 +179,30 @@ func GetBlockLogs(ctx context.Context, odr OdrBackend, hash common.Hash, number
 	return logs, nil
 }
 
+// GetUntrustedBlockLogs retrieves the logs generated by the transactions included in a
+// block. The retrieved logs are regarded as untrusted and will not be stored in the
+// database. This function should only be used in light client checkpoint syncing.
+func GetUntrustedBlockLogs(ctx context.Context, odr OdrBackend, header *types.Header) ([][]*types.Log, error) {
+	// Retrieve the potentially incomplete receipts from disk or network
+	hash, number := header.Hash(), header.Number.Uint64()
+	receipts := rawdb.ReadRawReceipts(odr.Database(), hash, number)
+	if receipts == nil {
+		r := &ReceiptsRequest{Hash: hash, Number: number, Header: header, Untrusted: true}
+		if err := odr.Retrieve(ctx, r); err != nil {
+			return nil, err
+		}
+		receipts = r.Receipts
+		// Untrusted receipts won't be stored in the database. Therefore
+		// derived fields computation is unnecessary.
+	}
+	// Return the logs without deriving any computed fields on the receipts
+	logs := make([][]*types.Log, len(receipts))
+	for i, receipt := range receipts {
+		logs[i] = receipt.Logs
+	}
+	return logs, nil
+}
+
 // GetBloomBits retrieves a batch of compressed bloomBits vectors belonging to the given bit index and section indexes
 func GetBloomBits(ctx context.Context, odr OdrBackend, bitIdx uint, sectionIdxList []uint64) ([][]byte, error) {
 	var (

node/node.go

@@ -247,7 +247,6 @@ func (n *Node) Start() error {
 	n.services = services
 	n.server = running
 	n.stop = make(chan struct{})
-
 	return nil
 }
 

p2p/message.go

@@ -169,7 +169,7 @@ type MsgPipeRW struct {
 	closed  *int32
 }
 
-// WriteMsg sends a messsage on the pipe.
+// WriteMsg sends a message on the pipe.
 // It blocks until the receiver has consumed the message payload.
 func (p *MsgPipeRW) WriteMsg(msg Msg) error {
 	if atomic.LoadInt32(p.closed) == 0 {

params/config.go

@@ -17,10 +17,12 @@
 package params
 
 import (
+	"encoding/binary"
 	"fmt"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
 )
 
 // Genesis hashes to enforce below configs on.
@@ -108,6 +110,17 @@ var (
 			Period: 15,
 			Epoch:  30000,
 		},
+		CheckpointContract: &CheckpointContractConfig{
+			Name:         "rinkeby",
+			ContractAddr: common.HexToAddress("0x62652ed8e969ce7bd5e3dd13590efa1e569215f1"),
+			Signers: []common.Address{
+				common.HexToAddress("0xd9c9cd5f6779558b6e0ed4e6acf6b1947e7fa1f3"), // Peter
+				common.HexToAddress("0x78d1ad571a1a09d60d9bbf25894b44e4c8859595"), // Martin
+				common.HexToAddress("0x286834935f4A8Cfb4FF4C77D5770C2775aE2b0E7"), // Zsolt
+				common.HexToAddress("0xb86e2B0Ab5A4B1373e40c51A7C712c70Ba2f9f8E"), // Gary
+			},
+			Threshold: 2,
+		},
 	}
 
 	// RinkebyTrustedCheckpoint contains the light client trusted checkpoint for the Rinkeby test network.
@@ -151,16 +164,16 @@ var (
 	//
 	// This configuration is intentionally not using keyed fields to force anyone
 	// adding flags to the config to also have to set these fields.
-	AllEthashProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil}
+	AllEthashProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil, nil}
 
 	// AllCliqueProtocolChanges contains every protocol change (EIPs) introduced
 	// and accepted by the Ethereum core developers into the Clique consensus.
 	//
 	// This configuration is intentionally not using keyed fields to force anyone
 	// adding flags to the config to also have to set these fields.
-	AllCliqueProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, &CliqueConfig{Period: 0, Epoch: 30000}}
+	AllCliqueProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, &CliqueConfig{Period: 0, Epoch: 30000}, nil}
 
-	TestChainConfig = &ChainConfig{big.NewInt(1), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil}
+	TestChainConfig = &ChainConfig{big.NewInt(1), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil, nil}
 	TestRules       = TestChainConfig.Rules(new(big.Int))
 )
 
@@ -176,6 +189,38 @@ type TrustedCheckpoint struct {
 	BloomRoot    common.Hash `json:"bloomRoot"`
 }
 
+// HashEqual returns an indicator comparing the itself hash with given one.
+func (c *TrustedCheckpoint) HashEqual(hash common.Hash) bool {
+	if c.Empty() {
+		return hash == common.Hash{}
+	}
+	return c.Hash() == hash
+}
+
+// Hash returns the hash of checkpoint's four key fields(index, sectionHead, chtRoot and bloomTrieRoot).
+func (c *TrustedCheckpoint) Hash() common.Hash {
+	buf := make([]byte, 8+3*common.HashLength)
+	binary.BigEndian.PutUint64(buf, c.SectionIndex)
+	copy(buf[8:], c.SectionHead.Bytes())
+	copy(buf[8+common.HashLength:], c.CHTRoot.Bytes())
+	copy(buf[8+2*common.HashLength:], c.BloomRoot.Bytes())
+	return crypto.Keccak256Hash(buf)
+}
+
+// Empty returns an indicator whether the checkpoint is regarded as empty.
+func (c *TrustedCheckpoint) Empty() bool {
+	return c.SectionHead == (common.Hash{}) || c.CHTRoot == (common.Hash{}) || c.BloomRoot == (common.Hash{})
+}
+
+// CheckpointContractConfig represents a set of checkpoint contract config
+// which used for light client checkpoint syncing.
+type CheckpointContractConfig struct {
+	Name         string           `json:"-"`
+	ContractAddr common.Address   `json:"contractAddr"`
+	Signers      []common.Address `json:"signers"`
+	Threshold    uint64           `json:"threshold"`
+}
+
 // ChainConfig is the core config which determines the blockchain settings.
 //
 // ChainConfig is stored in the database on a per block basis. This means
@@ -204,6 +249,9 @@ type ChainConfig struct {
 	// Various consensus engines
 	Ethash *EthashConfig `json:"ethash,omitempty"`
 	Clique *CliqueConfig `json:"clique,omitempty"`
+
+	// Checkpoint contract configs
+	CheckpointContract *CheckpointContractConfig `json:"checkpointContract,omitempty"`
 }
 
 // EthashConfig is the consensus engine configs for proof-of-work based sealing.

params/network_params.go

@@ -47,6 +47,12 @@ const (
 	// is generated
 	HelperTrieProcessConfirmations = 256
 
+	// CheckpointFrequency is the block frequency for creating checkpoint
+	CheckpointFrequency = 32768
+
+	// CheckpointProcessConfirmations is the number before a checkpoint is generated
+	CheckpointProcessConfirmations = 256
+
 	// ImmutabilityThreshold is the number of blocks after which a chain segment is
 	// considered immutable (i.e. soft finality). It is used by the downloader as a
 	// hard limit against deep ancestors, by the blockchain against deep reorgs, by