cmd, eth: added light client and light server modes

11 files changed, 193 insertions, 83 deletions

diff --git a/eth/backend.go b/eth/backend.go
index 9c5e11a59..10018aeaa 100644
--- a/eth/backend.go
+++ b/eth/backend.go
@@ -66,9 +66,14 @@ var (
 type Config struct {
 	ChainConfig *core.ChainConfig // chain configuration
 
-	NetworkId int    // Network ID to use for selecting peers to connect to
-	Genesis   string // Genesis JSON to seed the chain database with
-	FastSync  bool   // Enables the state download based fast synchronisation algorithm
+	NetworkId  int    // Network ID to use for selecting peers to connect to
+	Genesis    string // Genesis JSON to seed the chain database with
+	FastSync   bool   // Enables the state download based fast synchronisation algorithm
+	LightMode  bool   // Running in light client mode
+	NoDefSrv   bool   // No default LES server
+	LightServ  int    // Maximum percentage of time allowed for serving LES requests
+	LightPeers int    // Maximum number of LES client peers
+	MaxPeers   int    // Maximum number of global peers
 
 	SkipBcVersionCheck bool // e.g. blockchain export
 	DatabaseCache      int
@@ -100,6 +105,12 @@ type Config struct {
 	TestGenesisState ethdb.Database // Genesis state to seed the database with (testing only!)
 }
 
+type LesServer interface {
+	Start()
+	Stop()
+	Protocols() []p2p.Protocol
+}
+
 // Ethereum implements the Ethereum full node service.
 type Ethereum struct {
 	chainConfig *core.ChainConfig
@@ -111,6 +122,7 @@ type Ethereum struct {
 	txMu            sync.Mutex
 	blockchain      *core.BlockChain
 	protocolManager *ProtocolManager
+	lesServer       LesServer
 	// DB interfaces
 	chainDb ethdb.Database // Block chain database
 
@@ -119,7 +131,7 @@ type Ethereum struct {
 	httpclient     *httpclient.HTTPClient
 	accountManager *accounts.Manager
 
-	apiBackend *EthApiBackend
+	ApiBackend *EthApiBackend
 
 	miner        *miner.Miner
 	Mining       bool
@@ -135,10 +147,14 @@ type Ethereum struct {
 	netRPCService *ethapi.PublicNetAPI
 }
 
+func (s *Ethereum) AddLesServer(ls LesServer) {
+	s.lesServer = ls
+}
+
 // New creates a new Ethereum object (including the
 // initialisation of the common Ethereum object)
 func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
-	chainDb, err := createDB(ctx, config)
+	chainDb, err := CreateDB(ctx, config, "chaindata")
 	if err != nil {
 		return nil, err
 	}
@@ -217,7 +233,18 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 	newPool := core.NewTxPool(eth.chainConfig, eth.EventMux(), eth.blockchain.State, eth.blockchain.GasLimit)
 	eth.txPool = newPool
 
-	if eth.protocolManager, err = NewProtocolManager(eth.chainConfig, config.FastSync, config.NetworkId, eth.eventMux, eth.txPool, eth.pow, eth.blockchain, chainDb); err != nil {
+	maxPeers := config.MaxPeers
+	if config.LightServ > 0 {
+		// if we are running a light server, limit the number of ETH peers so that we reserve some space for incoming LES connections
+		// temporary solution until the new peer connectivity API is finished
+		halfPeers := maxPeers / 2
+		maxPeers -= config.LightPeers
+		if maxPeers < halfPeers {
+			maxPeers = halfPeers
+		}
+	}
+
+	if eth.protocolManager, err = NewProtocolManager(eth.chainConfig, config.FastSync, config.NetworkId, maxPeers, eth.eventMux, eth.txPool, eth.pow, eth.blockchain, chainDb); err != nil {
 		return nil, err
 	}
 	eth.miner = miner.New(eth, eth.chainConfig, eth.EventMux(), eth.pow)
@@ -233,14 +260,14 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 		GpobaseCorrectionFactor: config.GpobaseCorrectionFactor,
 	}
 	gpo := gasprice.NewGasPriceOracle(eth.blockchain, chainDb, eth.eventMux, gpoParams)
-	eth.apiBackend = &EthApiBackend{eth, gpo}
+	eth.ApiBackend = &EthApiBackend{eth, gpo}
 
 	return eth, nil
 }
 
-// createDB creates the chain database.
-func createDB(ctx *node.ServiceContext, config *Config) (ethdb.Database, error) {
-	db, err := ctx.OpenDatabase("chaindata", config.DatabaseCache, config.DatabaseHandles)
+// CreateDB creates the chain database.
+func CreateDB(ctx *node.ServiceContext, config *Config, name string) (ethdb.Database, error) {
+	db, err := ctx.OpenDatabase(name, config.DatabaseCache, config.DatabaseHandles)
 	if db, ok := db.(*ethdb.LDBDatabase); ok {
 		db.Meter("eth/db/chaindata/")
 	}
@@ -288,7 +315,7 @@ func CreatePoW(config *Config) (*ethash.Ethash, error) {
 // APIs returns the collection of RPC services the ethereum package offers.
 // NOTE, some of these services probably need to be moved to somewhere else.
 func (s *Ethereum) APIs() []rpc.API {
-	return append(ethapi.GetAPIs(s.apiBackend, s.solcPath), []rpc.API{
+	return append(ethapi.GetAPIs(s.ApiBackend, s.solcPath), []rpc.API{
 		{
 			Namespace: "eth",
 			Version:   "1.0",
@@ -391,7 +418,11 @@ func (s *Ethereum) Downloader() *downloader.Downloader { return s.protocolManage
 // Protocols implements node.Service, returning all the currently configured
 // network protocols to start.
 func (s *Ethereum) Protocols() []p2p.Protocol {
-	return s.protocolManager.SubProtocols
+	if s.lesServer == nil {
+		return s.protocolManager.SubProtocols
+	} else {
+		return append(s.protocolManager.SubProtocols, s.lesServer.Protocols()...)
+	}
 }
 
 // Start implements node.Service, starting all internal goroutines needed by the
@@ -402,6 +433,9 @@ func (s *Ethereum) Start(srvr *p2p.Server) error {
 		s.StartAutoDAG()
 	}
 	s.protocolManager.Start()
+	if s.lesServer != nil {
+		s.lesServer.Start()
+	}
 	return nil
 }
 
@@ -413,6 +447,9 @@ func (s *Ethereum) Stop() error {
 	}
 	s.blockchain.Stop()
 	s.protocolManager.Stop()
+	if s.lesServer != nil {
+		s.lesServer.Stop()
+	}
 	s.txPool.Stop()
 	s.miner.Stop()
 	s.eventMux.Stop()
diff --git a/eth/bind.go b/eth/bind.go
index 532e94460..0931c5f3b 100644
--- a/eth/bind.go
+++ b/eth/bind.go
@@ -43,11 +43,11 @@ type ContractBackend struct {
 
 // NewContractBackend creates a new native contract backend using an existing
 // Etheruem object.
-func NewContractBackend(eth *Ethereum) *ContractBackend {
+func NewContractBackend(apiBackend ethapi.Backend) *ContractBackend {
 	return &ContractBackend{
-		eapi:  ethapi.NewPublicEthereumAPI(eth.apiBackend),
-		bcapi: ethapi.NewPublicBlockChainAPI(eth.apiBackend),
-		txapi: ethapi.NewPublicTransactionPoolAPI(eth.apiBackend),
+		eapi:  ethapi.NewPublicEthereumAPI(apiBackend),
+		bcapi: ethapi.NewPublicBlockChainAPI(apiBackend),
+		txapi: ethapi.NewPublicTransactionPoolAPI(apiBackend),
 	}
 }
 
diff --git a/eth/downloader/downloader.go b/eth/downloader/downloader.go
index da20e48a2..b1f4b8169 100644
--- a/eth/downloader/downloader.go
+++ b/eth/downloader/downloader.go
@@ -164,13 +164,13 @@ type Downloader struct {
 }
 
 // New creates a new downloader to fetch hashes and blocks from remote peers.
-func New(stateDb ethdb.Database, mux *event.TypeMux, hasHeader headerCheckFn, hasBlockAndState blockAndStateCheckFn,
+func New(mode SyncMode, stateDb ethdb.Database, mux *event.TypeMux, hasHeader headerCheckFn, hasBlockAndState blockAndStateCheckFn,
 	getHeader headerRetrievalFn, getBlock blockRetrievalFn, headHeader headHeaderRetrievalFn, headBlock headBlockRetrievalFn,
 	headFastBlock headFastBlockRetrievalFn, commitHeadBlock headBlockCommitterFn, getTd tdRetrievalFn, insertHeaders headerChainInsertFn,
 	insertBlocks blockChainInsertFn, insertReceipts receiptChainInsertFn, rollback chainRollbackFn, dropPeer peerDropFn) *Downloader {
 
 	dl := &Downloader{
-		mode:             FullSync,
+		mode:             mode,
 		mux:              mux,
 		queue:            newQueue(stateDb),
 		peers:            newPeerSet(),
@@ -1179,10 +1179,23 @@ func (d *Downloader) processHeaders(origin uint64, td *big.Int) error {
 			for i, header := range rollback {
 				hashes[i] = header.Hash()
 			}
-			lastHeader, lastFastBlock, lastBlock := d.headHeader().Number, d.headFastBlock().Number(), d.headBlock().Number()
+			lastHeader, lastFastBlock, lastBlock := d.headHeader().Number, common.Big0, common.Big0
+			if d.headFastBlock != nil {
+				lastFastBlock = d.headFastBlock().Number()
+			}
+			if d.headBlock != nil {
+				lastBlock = d.headBlock().Number()
+			}
 			d.rollback(hashes)
+			curFastBlock, curBlock := common.Big0, common.Big0
+			if d.headFastBlock != nil {
+				curFastBlock = d.headFastBlock().Number()
+			}
+			if d.headBlock != nil {
+				curBlock = d.headBlock().Number()
+			}
 			glog.V(logger.Warn).Infof("Rolled back %d headers (LH: %d->%d, FB: %d->%d, LB: %d->%d)",
-				len(hashes), lastHeader, d.headHeader().Number, lastFastBlock, d.headFastBlock().Number(), lastBlock, d.headBlock().Number())
+				len(hashes), lastHeader, d.headHeader().Number, lastFastBlock, curFastBlock, lastBlock, curBlock)
 
 			// If we're already past the pivot point, this could be an attack, thread carefully
 			if rollback[len(rollback)-1].Number.Uint64() > pivot {
@@ -1229,8 +1242,10 @@ func (d *Downloader) processHeaders(origin uint64, td *big.Int) error {
 				// L: Sync begins, and finds common ancestor at 11
 				// L: Request new headers up from 11 (R's TD was higher, it must have something)
 				// R: Nothing to give
-				if !gotHeaders && td.Cmp(d.getTd(d.headBlock().Hash())) > 0 {
-					return errStallingPeer
+				if d.mode != LightSync {
+					if !gotHeaders && td.Cmp(d.getTd(d.headBlock().Hash())) > 0 {
+						return errStallingPeer
+					}
 				}
 				// If fast or light syncing, ensure promised headers are indeed delivered. This is
 				// needed to detect scenarios where an attacker feeds a bad pivot and then bails out
diff --git a/eth/downloader/downloader_test.go b/eth/downloader/downloader_test.go
index 2849712ab..ff8cd1044 100644
--- a/eth/downloader/downloader_test.go
+++ b/eth/downloader/downloader_test.go
@@ -96,7 +96,7 @@ func newTester() *downloadTester {
 	tester.stateDb, _ = ethdb.NewMemDatabase()
 	tester.stateDb.Put(genesis.Root().Bytes(), []byte{0x00})
 
-	tester.downloader = New(tester.stateDb, new(event.TypeMux), tester.hasHeader, tester.hasBlock, tester.getHeader,
+	tester.downloader = New(FullSync, tester.stateDb, new(event.TypeMux), tester.hasHeader, tester.hasBlock, tester.getHeader,
 		tester.getBlock, tester.headHeader, tester.headBlock, tester.headFastBlock, tester.commitHeadBlock, tester.getTd,
 		tester.insertHeaders, tester.insertBlocks, tester.insertReceipts, tester.rollback, tester.dropPeer)
 
diff --git a/eth/filters/api.go b/eth/filters/api.go
index fa4bef283..834513262 100644
--- a/eth/filters/api.go
+++ b/eth/filters/api.go
@@ -52,6 +52,8 @@ type filter struct {
 // PublicFilterAPI offers support to create and manage filters. This will allow external clients to retrieve various
 // information related to the Ethereum protocol such als blocks, transactions and logs.
 type PublicFilterAPI struct {
+	backend   Backend
+	useMipMap bool
 	mux       *event.TypeMux
 	quit      chan struct{}
 	chainDb   ethdb.Database
@@ -316,7 +318,7 @@ func (api *PublicFilterAPI) NewFilter(crit FilterCriteria) rpc.ID {
 // GetLogs returns logs matching the given argument that are stored within the state.
 //
 // https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_getlogs
-func (api *PublicFilterAPI) GetLogs(crit FilterCriteria) []Log {
+func (api *PublicFilterAPI) GetLogs(ctx context.Context, crit FilterCriteria) ([]Log, error) {
 	if crit.FromBlock == nil {
 		crit.FromBlock = big.NewInt(rpc.LatestBlockNumber.Int64())
 	}
@@ -324,13 +326,14 @@ func (api *PublicFilterAPI) GetLogs(crit FilterCriteria) []Log {
 		crit.ToBlock = big.NewInt(rpc.LatestBlockNumber.Int64())
 	}
 
-	filter := New(api.chainDb)
+	filter := New(api.backend, api.useMipMap)
 	filter.SetBeginBlock(crit.FromBlock.Int64())
 	filter.SetEndBlock(crit.ToBlock.Int64())
 	filter.SetAddresses(crit.Addresses)
 	filter.SetTopics(crit.Topics)
 
-	return returnLogs(filter.Find())
+	logs, err := filter.Find(ctx)
+	return returnLogs(logs), err
 }
 
 // UninstallFilter removes the filter with the given filter id.
@@ -354,22 +357,23 @@ func (api *PublicFilterAPI) UninstallFilter(id rpc.ID) bool {
 // If the filter could not be found an empty array of logs is returned.
 //
 // https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_getfilterlogs
-func (api *PublicFilterAPI) GetFilterLogs(id rpc.ID) []Log {
+func (api *PublicFilterAPI) GetFilterLogs(ctx context.Context, id rpc.ID) ([]Log, error) {
 	api.filtersMu.Lock()
 	f, found := api.filters[id]
 	api.filtersMu.Unlock()
 
 	if !found || f.typ != LogsSubscription {
-		return []Log{}
+		return []Log{}, nil
 	}
 
-	filter := New(api.chainDb)
+	filter := New(api.backend, api.useMipMap)
 	filter.SetBeginBlock(f.crit.FromBlock.Int64())
 	filter.SetEndBlock(f.crit.ToBlock.Int64())
 	filter.SetAddresses(f.crit.Addresses)
 	filter.SetTopics(f.crit.Topics)
 
-	return returnLogs(filter.Find())
+	logs, err := filter.Find(ctx)
+	return returnLogs(logs), err
 }
 
 // GetFilterChanges returns the logs for the filter with the given id since
diff --git a/eth/filters/filter.go b/eth/filters/filter.go
index d181d0892..4004af300 100644
--- a/eth/filters/filter.go
+++ b/eth/filters/filter.go
@@ -24,10 +24,23 @@ import (
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/event"
+	"github.com/ethereum/go-ethereum/rpc"
+	"golang.org/x/net/context"
 )
 
+type Backend interface {
+	ChainDb() ethdb.Database
+	EventMux() *event.TypeMux
+	HeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*types.Header, error)
+	GetReceipts(ctx context.Context, blockHash common.Hash) (types.Receipts, error)
+}
+
 // Filter can be used to retrieve and filter logs
 type Filter struct {
+	backend   Backend
+	useMipMap bool
+
 	created time.Time
 
 	db         ethdb.Database
@@ -38,8 +51,12 @@ type Filter struct {
 
 // New creates a new filter which uses a bloom filter on blocks to figure out whether
 // a particular block is interesting or not.
-func New(db ethdb.Database) *Filter {
-	return &Filter{db: db}
+func New(backend Backend, useMipMap bool) *Filter {
+	return &Filter{
+		backend:   backend,
+		useMipMap: useMipMap,
+		db:        backend.ChainDb(),
+	}
 }
 
 // SetBeginBlock sets the earliest block for filtering.
@@ -66,30 +83,29 @@ func (f *Filter) SetTopics(topics [][]common.Hash) {
 }
 
 // Run filters logs with the current parameters set
-func (f *Filter) Find() []Log {
-	latestHash := core.GetHeadBlockHash(f.db)
-	latestBlock := core.GetBlock(f.db, latestHash, core.GetBlockNumber(f.db, latestHash))
-	if latestBlock == nil {
-		return []Log{}
+func (f *Filter) Find(ctx context.Context) ([]Log, error) {
+	head, _ := f.backend.HeaderByNumber(ctx, rpc.LatestBlockNumber)
+	if head == nil {
+		return nil, nil
 	}
+	headBlockNumber := head.Number.Uint64()
 
 	var beginBlockNo uint64 = uint64(f.begin)
 	if f.begin == -1 {
-		beginBlockNo = latestBlock.NumberU64()
+		beginBlockNo = headBlockNumber
 	}
-
-	endBlockNo := uint64(f.end)
+	var endBlockNo uint64 = uint64(f.end)
 	if f.end == -1 {
-		endBlockNo = latestBlock.NumberU64()
+		endBlockNo = headBlockNumber
 	}
 
 	// if no addresses are present we can't make use of fast search which
 	// uses the mipmap bloom filters to check for fast inclusion and uses
 	// higher range probability in order to ensure at least a false positive
-	if len(f.addresses) == 0 {
-		return f.getLogs(beginBlockNo, endBlockNo)
+	if !f.useMipMap || len(f.addresses) == 0 {
+		return f.getLogs(ctx, beginBlockNo, endBlockNo)
 	}
-	return f.mipFind(beginBlockNo, endBlockNo, 0)
+	return f.mipFind(beginBlockNo, endBlockNo, 0), nil
 }
 
 func (f *Filter) mipFind(start, end uint64, depth int) (logs []Log) {
@@ -107,7 +123,8 @@ func (f *Filter) mipFind(start, end uint64, depth int) (logs []Log) {
 				start := uint64(math.Max(float64(num), float64(start)))
 				end := uint64(math.Min(float64(num+level-1), float64(end)))
 				if depth+1 == len(core.MIPMapLevels) {
-					logs = append(logs, f.getLogs(start, end)...)
+					l, _ := f.getLogs(context.Background(), start, end)
+					logs = append(logs, l...)
 				} else {
 					logs = append(logs, f.mipFind(start, end, depth+1)...)
 				}
@@ -122,28 +139,22 @@ func (f *Filter) mipFind(start, end uint64, depth int) (logs []Log) {
 	return logs
 }
 
-func (f *Filter) getLogs(start, end uint64) (logs []Log) {
-	var block *types.Block
-
+func (f *Filter) getLogs(ctx context.Context, start, end uint64) (logs []Log, err error) {
 	for i := start; i <= end; i++ {
-		hash := core.GetCanonicalHash(f.db, i)
-		if hash != (common.Hash{}) {
-			block = core.GetBlock(f.db, hash, i)
-		} else { // block not found
-			return logs
-		}
-		if block == nil { // block not found/written
-			return logs
+		header, err := f.backend.HeaderByNumber(ctx, rpc.BlockNumber(i))
+		if header == nil || err != nil {
+			return logs, err
 		}
 
 		// Use bloom filtering to see if this block is interesting given the
 		// current parameters
-		if f.bloomFilter(block) {
+		if f.bloomFilter(header.Bloom) {
 			// Get the logs of the block
-			var (
-				receipts   = core.GetBlockReceipts(f.db, block.Hash(), i)
-				unfiltered []Log
-			)
+			receipts, err := f.backend.GetReceipts(ctx, header.Hash())
+			if err != nil {
+				return nil, err
+			}
+			var unfiltered []Log
 			for _, receipt := range receipts {
 				rl := make([]Log, len(receipt.Logs))
 				for i, l := range receipt.Logs {
@@ -155,7 +166,7 @@ func (f *Filter) getLogs(start, end uint64) (logs []Log) {
 		}
 	}
 
-	return logs
+	return logs, nil
 }
 
 func includes(addresses []common.Address, a common.Address) bool {
@@ -229,7 +240,7 @@ func bloomFilter(bloom types.Bloom, addresses []common.Address, topics [][]commo
 	for _, sub := range topics {
 		var included bool
 		for _, topic := range sub {
-			if (topic == common.Hash{}) || types.BloomLookup(block.Bloom(), topic) {
+			if (topic == common.Hash{}) || types.BloomLookup(bloom, topic) {
 				included = true
 				break
 			}
diff --git a/eth/filters/filter_system_test.go b/eth/filters/filter_system_test.go
index 1bd4d502d..48d6811c0 100644
--- a/eth/filters/filter_system_test.go
+++ b/eth/filters/filter_system_test.go
@@ -22,6 +22,8 @@ import (
 	"testing"
 	"time"
 
+	"golang.org/x/net/context"
+
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -38,6 +40,37 @@ var (
 	api     = NewPublicFilterAPI(backend, false)
 )
 
+type testBackend struct {
+	mux *event.TypeMux
+	db  ethdb.Database
+}
+
+func (b *testBackend) ChainDb() ethdb.Database {
+	return b.db
+}
+
+func (b *testBackend) EventMux() *event.TypeMux {
+	return b.mux
+}
+
+func (b *testBackend) HeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*types.Header, error) {
+	var hash common.Hash
+	var num uint64
+	if blockNr == rpc.LatestBlockNumber {
+		hash = core.GetHeadBlockHash(b.db)
+		num = core.GetBlockNumber(b.db, hash)
+	} else {
+		num = uint64(blockNr)
+		hash = core.GetCanonicalHash(b.db, num)
+	}
+	return core.GetHeader(b.db, hash, num), nil
+}
+
+func (b *testBackend) GetReceipts(ctx context.Context, blockHash common.Hash) (types.Receipts, error) {
+	num := core.GetBlockNumber(b.db, blockHash)
+	return core.GetBlockReceipts(b.db, blockHash, num), nil
+}
+
 // TestBlockSubscription tests if a block subscription returns block hashes for posted chain events.
 // It creates multiple subscriptions:
 // - one at the start and should receive all posted chain events and a second (blockHashes)
diff --git a/eth/filters/filter_test.go b/eth/filters/filter_test.go
index 7b714f5d5..e0b24046c 100644
--- a/eth/filters/filter_test.go
+++ b/eth/filters/filter_test.go
@@ -22,6 +22,8 @@ import (
 	"os"
 	"testing"
 
+	"golang.org/x/net/context"
+
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -48,6 +50,7 @@ func BenchmarkMipmaps(b *testing.B) {
 
 	var (
 		db, _   = ethdb.NewLDBDatabase(dir, 0, 0)
+		backend = &testBackend{mux, db}
 		key1, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
 		addr1   = crypto.PubkeyToAddress(key1.PublicKey)
 		addr2   = common.BytesToAddress([]byte("jeff"))
@@ -100,13 +103,13 @@ func BenchmarkMipmaps(b *testing.B) {
 	}
 	b.ResetTimer()
 
-	filter := New(db)
+	filter := New(backend, true)
 	filter.SetAddresses([]common.Address{addr1, addr2, addr3, addr4})
 	filter.SetBeginBlock(0)
 	filter.SetEndBlock(-1)
 
 	for i := 0; i < b.N; i++ {
-		logs := filter.Find()
+		logs, _ := filter.Find(context.Background())
 		if len(logs) != 4 {
 			b.Fatal("expected 4 log, got", len(logs))
 		}
@@ -122,6 +125,7 @@ func TestFilters(t *testing.T) {
 
 	var (
 		db, _   = ethdb.NewLDBDatabase(dir, 0, 0)
+		backend = &testBackend{mux, db}
 		key1, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
 		addr    = crypto.PubkeyToAddress(key1.PublicKey)
 
@@ -201,23 +205,23 @@ func TestFilters(t *testing.T) {
 		}
 	}
 
-	filter := New(db)
+	filter := New(backend, true)
 	filter.SetAddresses([]common.Address{addr})
 	filter.SetTopics([][]common.Hash{[]common.Hash{hash1, hash2, hash3, hash4}})
 	filter.SetBeginBlock(0)
 	filter.SetEndBlock(-1)
 
-	logs := filter.Find()
+	logs, _ := filter.Find(context.Background())
 	if len(logs) != 4 {
 		t.Error("expected 4 log, got", len(logs))
 	}
 
-	filter = New(db)
+	filter = New(backend, true)
 	filter.SetAddresses([]common.Address{addr})
 	filter.SetTopics([][]common.Hash{[]common.Hash{hash3}})
 	filter.SetBeginBlock(900)
 	filter.SetEndBlock(999)
-	logs = filter.Find()
+	logs, _ = filter.Find(context.Background())
 	if len(logs) != 1 {
 		t.Error("expected 1 log, got", len(logs))
 	}
@@ -225,12 +229,12 @@ func TestFilters(t *testing.T) {
 		t.Errorf("expected log[0].Topics[0] to be %x, got %x", hash3, logs[0].Topics[0])
 	}
 
-	filter = New(db)
+	filter = New(backend, true)
 	filter.SetAddresses([]common.Address{addr})
 	filter.SetTopics([][]common.Hash{[]common.Hash{hash3}})
 	filter.SetBeginBlock(990)
 	filter.SetEndBlock(-1)
-	logs = filter.Find()
+	logs, _ = filter.Find(context.Background())
 	if len(logs) != 1 {
 		t.Error("expected 1 log, got", len(logs))
 	}
@@ -238,44 +242,44 @@ func TestFilters(t *testing.T) {
 		t.Errorf("expected log[0].Topics[0] to be %x, got %x", hash3, logs[0].Topics[0])
 	}
 
-	filter = New(db)
+	filter = New(backend, true)
 	filter.SetTopics([][]common.Hash{[]common.Hash{hash1, hash2}})
 	filter.SetBeginBlock(1)
 	filter.SetEndBlock(10)
 
-	logs = filter.Find()
+	logs, _ = filter.Find(context.Background())
 	if len(logs) != 2 {
 		t.Error("expected 2 log, got", len(logs))
 	}
 
 	failHash := common.BytesToHash([]byte("fail"))
-	filter = New(db)
+	filter = New(backend, true)
 	filter.SetTopics([][]common.Hash{[]common.Hash{failHash}})
 	filter.SetBeginBlock(0)
 	filter.SetEndBlock(-1)
 
-	logs = filter.Find()
+	logs, _ = filter.Find(context.Background())
 	if len(logs) != 0 {
 		t.Error("expected 0 log, got", len(logs))
 	}
 
 	failAddr := common.BytesToAddress([]byte("failmenow"))
-	filter = New(db)
+	filter = New(backend, true)
 	filter.SetAddresses([]common.Address{failAddr})
 	filter.SetBeginBlock(0)
 	filter.SetEndBlock(-1)
 
-	logs = filter.Find()
+	logs, _ = filter.Find(context.Background())
 	if len(logs) != 0 {
 		t.Error("expected 0 log, got", len(logs))
 	}
 
-	filter = New(db)
+	filter = New(backend, true)
 	filter.SetTopics([][]common.Hash{[]common.Hash{failHash}, []common.Hash{hash1}})
 	filter.SetBeginBlock(0)
 	filter.SetEndBlock(-1)
 
-	logs = filter.Find()
+	logs, _ = filter.Find(context.Background())
 	if len(logs) != 0 {
 		t.Error("expected 0 log, got", len(logs))
 	}
diff --git a/eth/handler.go b/eth/handler.go
index e478990f7..9d6b1ced2 100644
--- a/eth/handler.go
+++ b/eth/handler.go
@@ -68,6 +68,7 @@ type ProtocolManager struct {
 	blockchain  *core.BlockChain
 	chaindb     ethdb.Database
 	chainconfig *core.ChainConfig
+	maxPeers    int
 
 	downloader *downloader.Downloader
 	fetcher    *fetcher.Fetcher
@@ -94,7 +95,7 @@ type ProtocolManager struct {
 
 // NewProtocolManager returns a new ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
 // with the ethereum network.
-func NewProtocolManager(config *core.ChainConfig, fastSync bool, networkId int, mux *event.TypeMux, txpool txPool, pow pow.PoW, blockchain *core.BlockChain, chaindb ethdb.Database) (*ProtocolManager, error) {
+func NewProtocolManager(config *core.ChainConfig, fastSync bool, networkId int, maxPeers int, mux *event.TypeMux, txpool txPool, pow pow.PoW, blockchain *core.BlockChain, chaindb ethdb.Database) (*ProtocolManager, error) {
 	// Create the protocol manager with the base fields
 	manager := &ProtocolManager{
 		networkId:   networkId,
@@ -103,6 +104,7 @@ func NewProtocolManager(config *core.ChainConfig, fastSync bool, networkId int,
 		blockchain:  blockchain,
 		chaindb:     chaindb,
 		chainconfig: config,
+		maxPeers:    maxPeers,
 		peers:       newPeerSet(),
 		newPeerCh:   make(chan *peer),
 		noMorePeers: make(chan struct{}),
@@ -156,7 +158,7 @@ func NewProtocolManager(config *core.ChainConfig, fastSync bool, networkId int,
 		return nil, errIncompatibleConfig
 	}
 	// Construct the different synchronisation mechanisms
-	manager.downloader = downloader.New(chaindb, manager.eventMux, blockchain.HasHeader, blockchain.HasBlockAndState, blockchain.GetHeaderByHash,
+	manager.downloader = downloader.New(downloader.FullSync, chaindb, manager.eventMux, blockchain.HasHeader, blockchain.HasBlockAndState, blockchain.GetHeaderByHash,
 		blockchain.GetBlockByHash, blockchain.CurrentHeader, blockchain.CurrentBlock, blockchain.CurrentFastBlock, blockchain.FastSyncCommitHead,
 		blockchain.GetTdByHash, blockchain.InsertHeaderChain, manager.insertChain, blockchain.InsertReceiptChain, blockchain.Rollback,
 		manager.removePeer)
@@ -253,6 +255,10 @@ func (pm *ProtocolManager) newPeer(pv int, p *p2p.Peer, rw p2p.MsgReadWriter) *p
 // handle is the callback invoked to manage the life cycle of an eth peer. When
 // this function terminates, the peer is disconnected.
 func (pm *ProtocolManager) handle(p *peer) error {
+	if pm.peers.Len() >= pm.maxPeers {
+		return p2p.DiscTooManyPeers
+	}
+
 	glog.V(logger.Debug).Infof("%v: peer connected [%s]", p, p.Name())
 
 	// Execute the Ethereum handshake
diff --git a/eth/handler_test.go b/eth/handler_test.go
index f0f18d0a6..64449afda 100644
--- a/eth/handler_test.go
+++ b/eth/handler_test.go
@@ -469,7 +469,7 @@ func testDAOChallenge(t *testing.T, localForked, remoteForked bool, timeout bool
 		config        = &core.ChainConfig{DAOForkBlock: big.NewInt(1), DAOForkSupport: localForked}
 		blockchain, _ = core.NewBlockChain(db, config, pow, evmux)
 	)
-	pm, err := NewProtocolManager(config, false, NetworkId, evmux, new(testTxPool), pow, blockchain, db)
+	pm, err := NewProtocolManager(config, false, NetworkId, 1000, evmux, new(testTxPool), pow, blockchain, db)
 	if err != nil {
 		t.Fatalf("failed to start test protocol manager: %v", err)
 	}
diff --git a/eth/helper_test.go b/eth/helper_test.go
index 732fe89ee..d5295b398 100644
--- a/eth/helper_test.go
+++ b/eth/helper_test.go
@@ -62,7 +62,7 @@ func newTestProtocolManager(fastSync bool, blocks int, generator func(int, *core
 		panic(err)
 	}
 
-	pm, err := NewProtocolManager(chainConfig, fastSync, NetworkId, evmux, &testTxPool{added: newtx}, pow, blockchain, db)
+	pm, err := NewProtocolManager(chainConfig, fastSync, NetworkId, 1000, evmux, &testTxPool{added: newtx}, pow, blockchain, db)
 	if err != nil {
 		return nil, err
 	}