path: root/eth/backend.go

// Copyright 2014 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 eth implements the Ethereum protocol.
package eth

import (
    "bytes"
    "crypto/ecdsa"
    "encoding/json"
    "fmt"
    "io/ioutil"
    "math/big"
    "os"
    "path/filepath"
    "regexp"
    "strings"
    "syscall"
    "time"

    "github.com/ethereum/ethash"
    "github.com/ethereum/go-ethereum/accounts"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/common/compiler"
    "github.com/ethereum/go-ethereum/common/httpclient"
    "github.com/ethereum/go-ethereum/core"
    "github.com/ethereum/go-ethereum/core/state"
    "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/downloader"
    "github.com/ethereum/go-ethereum/ethdb"
    "github.com/ethereum/go-ethereum/event"
    "github.com/ethereum/go-ethereum/logger"
    "github.com/ethereum/go-ethereum/logger/glog"
    "github.com/ethereum/go-ethereum/miner"
    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/p2p/discover"
    "github.com/ethereum/go-ethereum/p2p/nat"
    "github.com/ethereum/go-ethereum/rlp"
    "github.com/ethereum/go-ethereum/whisper"
)

const (
    epochLength    = 30000
    ethashRevision = 23

    autoDAGcheckInterval = 10 * time.Hour
    autoDAGepochHeight   = epochLength / 2
)

var (
    jsonlogger = logger.NewJsonLogger()

    datadirInUseErrNos = []uint{11, 32, 35}
    portInUseErrRE     = regexp.MustCompile("address already in use")

    defaultBootNodes = []*discover.Node{
        // ETH/DEV Go Bootnodes
        discover.MustParseNode("enode://a979fb575495b8d6db44f750317d0f4622bf4c2aa3365d6af7c284339968eef29b69ad0dce72a4d8db5ebb4968de0e3bec910127f134779fbcb0cb6d3331163c@52.16.188.185:30303"), // IE
        discover.MustParseNode("enode://de471bccee3d042261d52e9bff31458daecc406142b401d4cd848f677479f73104b9fdeb090af9583d3391b7f10cb2ba9e26865dd5fca4fcdc0fb1e3b723c786@54.94.239.50:30303"),  // BR
        discover.MustParseNode("enode://1118980bf48b0a3640bdba04e0fe78b1add18e1cd99bf22d53daac1fd9972ad650df52176e7c7d89d1114cfef2bc23a2959aa54998a46afcf7d91809f0855082@52.74.57.123:30303"),  // SG
        // ETH/DEV cpp-ethereum (poc-9.ethdev.com)
        discover.MustParseNode("enode://979b7fa28feeb35a4741660a16076f1943202cb72b6af70d327f053e248bab9ba81760f39d0701ef1d8f89cc1fbd2cacba0710a12cd5314d5e0c9021aa3637f9@5.1.83.226:30303"),
    }

    defaultTestNetBootNodes = []*discover.Node{
        discover.MustParseNode("enode://5374c1bff8df923d3706357eeb4983cd29a63be40a269aaa2296ee5f3b2119a8978c0ed68b8f6fc84aad0df18790417daadf91a4bfbb786a16c9b0a199fa254a@92.51.165.126:30303"),
    }

    staticNodes  = "static-nodes.json"  // Path within <datadir> to search for the static node list
    trustedNodes = "trusted-nodes.json" // Path within <datadir> to search for the trusted node list
)

type Config struct {
    DevMode bool
    TestNet bool

    Name         string
    NetworkId    int
    GenesisNonce int
    GenesisFile  string
    GenesisBlock *types.Block // used by block tests
    FastSync     bool
    Olympic      bool

    BlockChainVersion  int
    SkipBcVersionCheck bool // e.g. blockchain export
    DatabaseCache      int

    DataDir   string
    LogFile   string
    Verbosity int
    LogJSON   string
    VmDebug   bool
    NatSpec   bool
    DocRoot   string
    AutoDAG   bool
    PowTest   bool
    ExtraData []byte

    MaxPeers        int
    MaxPendingPeers int
    Discovery       bool
    Port            string

    // Space-separated list of discovery node URLs
    BootNodes string

    // This key is used to identify the node on the network.
    // If nil, an ephemeral key is used.
    NodeKey *ecdsa.PrivateKey

    NAT  nat.Interface
    Shh  bool
    Dial bool

    Etherbase      common.Address
    GasPrice       *big.Int
    MinerThreads   int
    AccountManager *accounts.Manager
    SolcPath       string

    GpoMinGasPrice          *big.Int
    GpoMaxGasPrice          *big.Int
    GpoFullBlockRatio       int
    GpobaseStepDown         int
    GpobaseStepUp           int
    GpobaseCorrectionFactor int

    // NewDB is used to create databases.
    // If nil, the default is to create leveldb databases on disk.
    NewDB func(path string) (ethdb.Database, error)
}

func (cfg *Config) parseBootNodes() []*discover.Node {
    if cfg.BootNodes == "" {
        if cfg.TestNet {
            return defaultTestNetBootNodes
        }

        return defaultBootNodes
    }
    var ns []*discover.Node
    for _, url := range strings.Split(cfg.BootNodes, " ") {
        if url == "" {
            continue
        }
        n, err := discover.ParseNode(url)
        if err != nil {
            glog.V(logger.Error).Infof("Bootstrap URL %s: %v\n", url, err)
            continue
        }
        ns = append(ns, n)
    }
    return ns
}

// parseNodes parses a list of discovery node URLs loaded from a .json file.
func (cfg *Config) parseNodes(file string) []*discover.Node {
    // Short circuit if no node config is present
    path := filepath.Join(cfg.DataDir, file)
    if _, err := os.Stat(path); err != nil {
        return nil
    }
    // Load the nodes from the config file
    blob, err := ioutil.ReadFile(path)
    if err != nil {
        glog.V(logger.Error).Infof("Failed to access nodes: %v", err)
        return nil
    }
    nodelist := []string{}
    if err := json.Unmarshal(blob, &nodelist); err != nil {
        glog.V(logger.Error).Infof("Failed to load nodes: %v", err)
        return nil
    }
    // Interpret the list as a discovery node array
    var nodes []*discover.Node
    for _, url := range nodelist {
        if url == "" {
            continue
        }
        node, err := discover.ParseNode(url)
        if err != nil {
            glog.V(logger.Error).Infof("Node URL %s: %v\n", url, err)
            continue
        }
        nodes = append(nodes, node)
    }
    return nodes
}

func (cfg *Config) nodeKey() (*ecdsa.PrivateKey, error) {
    // use explicit key from command line args if set
    if cfg.NodeKey != nil {
        return cfg.NodeKey, nil
    }
    // use persistent key if present
    keyfile := filepath.Join(cfg.DataDir, "nodekey")
    key, err := crypto.LoadECDSA(keyfile)
    if err == nil {
        return key, nil
    }
    // no persistent key, generate and store a new one
    if key, err = crypto.GenerateKey(); err != nil {
        return nil, fmt.Errorf("could not generate server key: %v", err)
    }
    if err := crypto.SaveECDSA(keyfile, key); err != nil {
        glog.V(logger.Error).Infoln("could not persist nodekey: ", err)
    }
    return key, nil
}

type Ethereum struct {
    // Channel for shutting down the ethereum
    shutdownChan chan bool

    // DB interfaces
    chainDb ethdb.Database // Block chain database
    dappDb  ethdb.Database // Dapp database

    //*** SERVICES ***
    // State manager for processing new blocks and managing the over all states
    blockProcessor  *core.BlockProcessor
    txPool          *core.TxPool
    blockchain      *core.BlockChain
    accountManager  *accounts.Manager
    whisper         *whisper.Whisper
    pow             *ethash.Ethash
    protocolManager *ProtocolManager
    SolcPath        string
    solc            *compiler.Solidity

    GpoMinGasPrice          *big.Int
    GpoMaxGasPrice          *big.Int
    GpoFullBlockRatio       int
    GpobaseStepDown         int
    GpobaseStepUp           int
    GpobaseCorrectionFactor int

    httpclient *httpclient.HTTPClient

    net      *p2p.Server
    eventMux *event.TypeMux
    miner    *miner.Miner

    // logger logger.LogSystem

    Mining        bool
    MinerThreads  int
    NatSpec       bool
    DataDir       string
    AutoDAG       bool
    PowTest       bool
    autodagquit   chan bool
    etherbase     common.Address
    clientVersion string
    netVersionId  int
    shhVersionId  int
}

func New(config *Config) (*Ethereum, error) {
    // Bootstrap database
    logger.New(config.DataDir, config.LogFile, config.Verbosity)
    if len(config.LogJSON) > 0 {
        logger.NewJSONsystem(config.DataDir, config.LogJSON)
    }

    // Let the database take 3/4 of the max open files (TODO figure out a way to get the actual limit of the open files)
    const dbCount = 3
    ethdb.OpenFileLimit = 128 / (dbCount + 1)

    newdb := config.NewDB
    if newdb == nil {
        newdb = func(path string) (ethdb.Database, error) { return ethdb.NewLDBDatabase(path, config.DatabaseCache) }
    }

    // Open the chain database and perform any upgrades needed
    chainDb, err := newdb(filepath.Join(config.DataDir, "chaindata"))
    if err != nil {
        var ok bool
        errno := uint(err.(syscall.Errno))
        for _, no := range datadirInUseErrNos {
            if errno == no {
                ok = true
                break
            }
        }
        if ok {
            err = fmt.Errorf("%v (check if another instance of geth is already running with the same data directory '%s')", err, config.DataDir)
        }
        return nil, fmt.Errorf("blockchain db err: %v", err)
    }
    if db, ok := chainDb.(*ethdb.LDBDatabase); ok {
        db.Meter("eth/db/chaindata/")
    }
    if err := upgradeChainDatabase(chainDb); err != nil {
        return nil, err
    }
    if err := addMipmapBloomBins(chainDb); err != nil {
        return nil, err
    }

    dappDb, err := newdb(filepath.Join(config.DataDir, "dapp"))
    if err != nil {
        var ok bool
        for _, no := range datadirInUseErrNos {
            if uint(err.(syscall.Errno)) == no {
                ok = true
                break
            }
        }
        if ok {
            err = fmt.Errorf("%v (check if another instance of geth is already running with the same data directory '%s')", err, config.DataDir)
        }
        return nil, fmt.Errorf("dapp db err: %v", err)
    }
    if db, ok := dappDb.(*ethdb.LDBDatabase); ok {
        db.Meter("eth/db/dapp/")
    }

    nodeDb := filepath.Join(config.DataDir, "nodes")
    glog.V(logger.Info).Infof("Protocol Versions: %v, Network Id: %v", ProtocolVersions, config.NetworkId)

    if len(config.GenesisFile) > 0 {
        fr, err := os.Open(config.GenesisFile)
        if err != nil {
            return nil, err
        }

        block, err := core.WriteGenesisBlock(chainDb, fr)
        if err != nil {
            return nil, err
        }
        glog.V(logger.Info).Infof("Successfully wrote genesis block. New genesis hash = %x\n", block.Hash())
    }

    // different modes
    switch {
    case config.Olympic:
        glog.V(logger.Error).Infoln("Starting Olympic network")
        fallthrough
    case config.DevMode:
        _, err := core.WriteOlympicGenesisBlock(chainDb, 42)
        if err != nil {
            return nil, err
        }
    case config.TestNet:
        state.StartingNonce = 1048576 // (2**20)
        _, err := core.WriteTestNetGenesisBlock(chainDb, 0x6d6f7264656e)
        if err != nil {
            return nil, err
        }
    }
    // This is for testing only.
    if config.GenesisBlock != nil {
        core.WriteTd(chainDb, config.GenesisBlock.Hash(), config.GenesisBlock.Difficulty())
        core.WriteBlock(chainDb, config.GenesisBlock)
        core.WriteCanonicalHash(chainDb, config.GenesisBlock.Hash(), config.GenesisBlock.NumberU64())
        core.WriteHeadBlockHash(chainDb, config.GenesisBlock.Hash())
    }

    if !config.SkipBcVersionCheck {
        b, _ := chainDb.Get([]byte("BlockchainVersion"))
        bcVersion := int(common.NewValue(b).Uint())
        if bcVersion != config.BlockChainVersion && bcVersion != 0 {
            return nil, fmt.Errorf("Blockchain DB version mismatch (%d / %d). Run geth upgradedb.\n", bcVersion, config.BlockChainVersion)
        }
        saveBlockchainVersion(chainDb, config.BlockChainVersion)
    }
    glog.V(logger.Info).Infof("Blockchain DB Version: %d", config.BlockChainVersion)

    eth := &Ethereum{
        shutdownChan:            make(chan bool),
        chainDb:                 chainDb,
        dappDb:                  dappDb,
        eventMux:                &event.TypeMux{},
        accountManager:          config.AccountManager,
        DataDir:                 config.DataDir,
        etherbase:               config.Etherbase,
        clientVersion:           config.Name, // TODO should separate from Name
        netVersionId:            config.NetworkId,
        NatSpec:                 config.NatSpec,
        MinerThreads:            config.MinerThreads,
        SolcPath:                config.SolcPath,
        AutoDAG:                 config.AutoDAG,
        PowTest:                 config.PowTest,
        GpoMinGasPrice:          config.GpoMinGasPrice,
        GpoMaxGasPrice:          config.GpoMaxGasPrice,
        GpoFullBlockRatio:       config.GpoFullBlockRatio,
        GpobaseStepDown:         config.GpobaseStepDown,
        GpobaseStepUp:           config.GpobaseStepUp,
        GpobaseCorrectionFactor: config.GpobaseCorrectionFactor,
        httpclient:              httpclient.New(config.DocRoot),
    }

    if config.PowTest {
        glog.V(logger.Info).Infof("ethash used in test mode")
        eth.pow, err = ethash.NewForTesting()
        if err != nil {
            return nil, err
        }
    } else {
        eth.pow = ethash.New()
    }
    //genesis := core.GenesisBlock(uint64(config.GenesisNonce), stateDb)
    eth.blockchain, err = core.NewBlockChain(chainDb, eth.pow, eth.EventMux())
    if err != nil {
        if err == core.ErrNoGenesis {
            return nil, fmt.Errorf(`Genesis block not found. Please supply a genesis block with the "--genesis /path/to/file" argument`)
        }
        return nil, err
    }
    newPool := core.NewTxPool(eth.EventMux(), eth.blockchain.State, eth.blockchain.GasLimit)
    eth.txPool = newPool

    eth.blockProcessor = core.NewBlockProcessor(chainDb, eth.pow, eth.blockchain, eth.EventMux())
    eth.blockchain.SetProcessor(eth.blockProcessor)
    if eth.protocolManager, err = NewProtocolManager(config.FastSync, config.NetworkId, eth.eventMux, eth.txPool, eth.pow, eth.blockchain, chainDb); err != nil {
        return nil, err
    }
    eth.miner = miner.New(eth, eth.EventMux(), eth.pow)
    eth.miner.SetGasPrice(config.GasPrice)
    eth.miner.SetExtra(config.ExtraData)

    if config.Shh {
        eth.whisper = whisper.New()
        eth.shhVersionId = int(eth.whisper.Version())
    }

    netprv, err := config.nodeKey()
    if err != nil {
        return nil, err
    }
    protocols := append([]p2p.Protocol{}, eth.protocolManager.SubProtocols...)
    if config.Shh {
        protocols = append(protocols, eth.whisper.Protocol())
    }
    eth.net = &p2p.Server{
        PrivateKey:      netprv,
        Name:            config.Name,
        MaxPeers:        config.MaxPeers,
        MaxPendingPeers: config.MaxPendingPeers,
        Discovery:       config.Discovery,
        Protocols:       protocols,
        NAT:             config.NAT,
        NoDial:          !config.Dial,
        BootstrapNodes:  config.parseBootNodes(),
        StaticNodes:     config.parseNodes(staticNodes),
        TrustedNodes:    config.parseNodes(trustedNodes),
        NodeDatabase:    nodeDb,
    }
    if len(config.Port) > 0 {
        eth.net.ListenAddr = ":" + config.Port
    }

    vm.Debug = config.VmDebug

    return eth, nil
}

type NodeInfo struct {
    Name       string
    NodeUrl    string
    NodeID     string
    IP         string
    DiscPort   int // UDP listening port for discovery protocol
    TCPPort    int // TCP listening port for RLPx
    Td         string
    ListenAddr string
}

func (s *Ethereum) NodeInfo() *NodeInfo {
    node := s.net.Self()

    return &NodeInfo{
        Name:       s.Name(),
        NodeUrl:    node.String(),
        NodeID:     node.ID.String(),
        IP:         node.IP.String(),
        DiscPort:   int(node.UDP),
        TCPPort:    int(node.TCP),
        ListenAddr: s.net.ListenAddr,
        Td:         s.BlockChain().GetTd(s.BlockChain().CurrentBlock().Hash()).String(),
    }
}

type PeerInfo struct {
    ID            string
    Name          string
    Caps          string
    RemoteAddress string
    LocalAddress  string
}

func newPeerInfo(peer *p2p.Peer) *PeerInfo {
    var caps []string
    for _, cap := range peer.Caps() {
        caps = append(caps, cap.String())
    }
    return &PeerInfo{
        ID:            peer.ID().String(),
        Name:          peer.Name(),
        Caps:          strings.Join(caps, ", "),
        RemoteAddress: peer.RemoteAddr().String(),
        LocalAddress:  peer.LocalAddr().String(),
    }
}

// PeersInfo returns an array of PeerInfo objects describing connected peers
func (s *Ethereum) PeersInfo() (peersinfo []*PeerInfo) {
    for _, peer := range s.net.Peers() {
        if peer != nil {
            peersinfo = append(peersinfo, newPeerInfo(peer))
        }
    }
    return
}

func (s *Ethereum) ResetWithGenesisBlock(gb *types.Block) {
    s.blockchain.ResetWithGenesisBlock(gb)
}

func (s *Ethereum) Etherbase() (eb common.Address, err error) {
    eb = s.etherbase
    if (eb == common.Address{}) {
        addr, e := s.AccountManager().AddressByIndex(0)
        if e != nil {
            err = fmt.Errorf("etherbase address must be explicitly specified")
        }
        eb = common.HexToAddress(addr)
    }
    return
}

// set in js console via admin interface or wrapper from cli flags
func (self *Ethereum) SetEtherbase(etherbase common.Address) {
    self.etherbase = etherbase
    self.miner.SetEtherbase(etherbase)
}

func (s *Ethereum) StopMining()         { s.miner.Stop() }
func (s *Ethereum) IsMining() bool      { return s.miner.Mining() }
func (s *Ethereum) Miner() *miner.Miner { return s.miner }

// func (s *Ethereum) Logger() logger.LogSystem             { return s.logger }
func (s *Ethereum) Name() string                         { return s.net.Name }
func (s *Ethereum) AccountManager() *accounts.Manager    { return s.accountManager }
func (s *Ethereum) BlockChain() *core.BlockChain         { return s.blockchain }
func (s *Ethereum) BlockProcessor() *core.BlockProcessor { return s.blockProcessor }
func (s *Ethereum) TxPool() *core.TxPool                 { return s.txPool }
func (s *Ethereum) Whisper() *whisper.Whisper            { return s.whisper }
func (s *Ethereum) EventMux() *event.TypeMux             { return s.eventMux }
func (s *Ethereum) ChainDb() ethdb.Database              { return s.chainDb }
func (s *Ethereum) DappDb() ethdb.Database               { return s.dappDb }
func (s *Ethereum) IsListening() bool                    { return true } // Always listening
func (s *Ethereum) PeerCount() int                       { return s.net.PeerCount() }
func (s *Ethereum) Peers() []*p2p.Peer                   { return s.net.Peers() }
func (s *Ethereum) MaxPeers() int                        { return s.net.MaxPeers }
func (s *Ethereum) ClientVersion() string                { return s.clientVersion }
func (s *Ethereum) EthVersion() int                      { return int(s.protocolManager.SubProtocols[0].Version) }
func (s *Ethereum) NetVersion() int                      { return s.netVersionId }
func (s *Ethereum) ShhVersion() int                      { return s.shhVersionId }
func (s *Ethereum) Downloader() *downloader.Downloader   { return s.protocolManager.downloader }

// Start the ethereum
func (s *Ethereum) Start() error {
    jsonlogger.LogJson(&logger.LogStarting{
        ClientString:    s.net.Name,
        ProtocolVersion: s.EthVersion(),
    })
    err := s.net.Start()
    if err != nil {
        if portInUseErrRE.MatchString(err.Error()) {
            err = fmt.Errorf("%v (possibly another instance of geth is using the same port)", err)
        }
        return err
    }

    if s.AutoDAG {
        s.StartAutoDAG()
    }

    s.protocolManager.Start()

    if s.whisper != nil {
        s.whisper.Start()
    }

    glog.V(logger.Info).Infoln("Server started")
    return nil
}

func (s *Ethereum) StartForTest() {
    jsonlogger.LogJson(&logger.LogStarting{
        ClientString:    s.net.Name,
        ProtocolVersion: s.EthVersion(),
    })
}

// AddPeer connects to the given node and maintains the connection until the
// server is shut down. If the connection fails for any reason, the server will
// attempt to reconnect the peer.
func (self *Ethereum) AddPeer(nodeURL string) error {
    n, err := discover.ParseNode(nodeURL)
    if err != nil {
        return fmt.Errorf("invalid node URL: %v", err)
    }
    self.net.AddPeer(n)
    return nil
}

func (s *Ethereum) Stop() {
    s.net.Stop()
    s.blockchain.Stop()
    s.protocolManager.Stop()
    s.txPool.Stop()
    s.eventMux.Stop()
    if s.whisper != nil {
        s.whisper.Stop()
    }
    s.StopAutoDAG()

    s.chainDb.Close()
    s.dappDb.Close()
    close(s.shutdownChan)
}

// This function will wait for a shutdown and resumes main thread execution
func (s *Ethereum) WaitForShutdown() {
    <-s.shutdownChan
}

// StartAutoDAG() spawns a go routine that checks the DAG every autoDAGcheckInterval
// by default that is 10 times per epoch
// in epoch n, if we past autoDAGepochHeight within-epoch blocks,
// it calls ethash.MakeDAG  to pregenerate the DAG for the next epoch n+1
// if it does not exist yet as well as remove the DAG for epoch n-1
// the loop quits if autodagquit channel is closed, it can safely restart and
// stop any number of times.
// For any more sophisticated pattern of DAG generation, use CLI subcommand
// makedag
func (self *Ethereum) StartAutoDAG() {
    if self.autodagquit != nil {
        return // already started
    }
    go func() {
        glog.V(logger.Info).Infof("Automatic pregeneration of ethash DAG ON (ethash dir: %s)", ethash.DefaultDir)
        var nextEpoch uint64
        timer := time.After(0)
        self.autodagquit = make(chan bool)
        for {
            select {
            case <-timer:
                glog.V(logger.Info).Infof("checking DAG (ethash dir: %s)", ethash.DefaultDir)
                currentBlock := self.BlockChain().CurrentBlock().NumberU64()
                thisEpoch := currentBlock / epochLength
                if nextEpoch <= thisEpoch {
                    if currentBlock%epochLength > autoDAGepochHeight {
                        if thisEpoch > 0 {
                            previousDag, previousDagFull := dagFiles(thisEpoch - 1)
                            os.Remove(filepath.Join(ethash.DefaultDir, previousDag))
                            os.Remove(filepath.Join(ethash.DefaultDir, previousDagFull))
                            glog.V(logger.Info).Infof("removed DAG for epoch %d (%s)", thisEpoch-1, previousDag)
                        }
                        nextEpoch = thisEpoch + 1
                        dag, _ := dagFiles(nextEpoch)
                        if _, err := os.Stat(dag); os.IsNotExist(err) {
                            glog.V(logger.Info).Infof("Pregenerating DAG for epoch %d (%s)", nextEpoch, dag)
                            err := ethash.MakeDAG(nextEpoch*epochLength, "") // "" -> ethash.DefaultDir
                            if err != nil {
                                glog.V(logger.Error).Infof("Error generating DAG for epoch %d (%s)", nextEpoch, dag)
                                return
                            }
                        } else {
                            glog.V(logger.Error).Infof("DAG for epoch %d (%s)", nextEpoch, dag)
                        }
                    }
                }
                timer = time.After(autoDAGcheckInterval)
            case <-self.autodagquit:
                return
            }
        }
    }()
}

// stopAutoDAG stops automatic DAG pregeneration by quitting the loop
func (self *Ethereum) StopAutoDAG() {
    if self.autodagquit != nil {
        close(self.autodagquit)
        self.autodagquit = nil
    }
    glog.V(logger.Info).Infof("Automatic pregeneration of ethash DAG OFF (ethash dir: %s)", ethash.DefaultDir)
}

// HTTPClient returns the light http client used for fetching offchain docs
// (natspec, source for verification)
func (self *Ethereum) HTTPClient() *httpclient.HTTPClient {
    return self.httpclient
}

func (self *Ethereum) Solc() (*compiler.Solidity, error) {
    var err error
    if self.solc == nil {
        self.solc, err = compiler.New(self.SolcPath)
    }
    return self.solc, err
}

// set in js console via admin interface or wrapper from cli flags
func (self *Ethereum) SetSolc(solcPath string) (*compiler.Solidity, error) {
    self.SolcPath = solcPath
    self.solc = nil
    return self.Solc()
}

// dagFiles(epoch) returns the two alternative DAG filenames (not a path)
// 1) <revision>-<hex(seedhash[8])> 2) full-R<revision>-<hex(seedhash[8])>
func dagFiles(epoch uint64) (string, string) {
    seedHash, _ := ethash.GetSeedHash(epoch * epochLength)
    dag := fmt.Sprintf("full-R%d-%x", ethashRevision, seedHash[:8])
    return dag, "full-R" + dag
}

func saveBlockchainVersion(db ethdb.Database, bcVersion int) {
    d, _ := db.Get([]byte("BlockchainVersion"))
    blockchainVersion := common.NewValue(d).Uint()

    if blockchainVersion == 0 {
        db.Put([]byte("BlockchainVersion"), common.NewValue(bcVersion).Bytes())
    }
}

// upgradeChainDatabase ensures that the chain database stores block split into
// separate header and body entries.
func upgradeChainDatabase(db ethdb.Database) error {
    // Short circuit if the head block is stored already as separate header and body
    data, err := db.Get([]byte("LastBlock"))
    if err != nil {
        return nil
    }
    head := common.BytesToHash(data)

    if block := core.GetBlockByHashOld(db, head); block == nil {
        return nil
    }
    // At least some of the database is still the old format, upgrade (skip the head block!)
    glog.V(logger.Info).Info("Old database detected, upgrading...")

    if db, ok := db.(*ethdb.LDBDatabase); ok {
        blockPrefix := []byte("block-hash-")
        for it := db.NewIterator(); it.Next(); {
            // Skip anything other than a combined block
            if !bytes.HasPrefix(it.Key(), blockPrefix) {
                continue
            }
            // Skip the head block (merge last to signal upgrade completion)
            if bytes.HasSuffix(it.Key(), head.Bytes()) {
                continue
            }
            // Load the block, split and serialize (order!)
            block := core.GetBlockByHashOld(db, common.BytesToHash(bytes.TrimPrefix(it.Key(), blockPrefix)))

            if err := core.WriteTd(db, block.Hash(), block.DeprecatedTd()); err != nil {
                return err
            }
            if err := core.WriteBody(db, block.Hash(), &types.Body{block.Transactions(), block.Uncles()}); err != nil {
                return err
            }
            if err := core.WriteHeader(db, block.Header()); err != nil {
                return err
            }
            if err := db.Delete(it.Key()); err != nil {
                return err
            }
        }
        // Lastly, upgrade the head block, disabling the upgrade mechanism
        current := core.GetBlockByHashOld(db, head)

        if err := core.WriteTd(db, current.Hash(), current.DeprecatedTd()); err != nil {
            return err
        }
        if err := core.WriteBody(db, current.Hash(), &types.Body{current.Transactions(), current.Uncles()}); err != nil {
            return err
        }
        if err := core.WriteHeader(db, current.Header()); err != nil {
            return err
        }
    }
    return nil
}

func addMipmapBloomBins(db ethdb.Database) (err error) {
    const mipmapVersion uint = 2

    // check if the version is set. We ignore data for now since there's
    // only one version so we can easily ignore it for now
    var data []byte
    data, _ = db.Get([]byte("setting-mipmap-version"))
    if len(data) > 0 {
        var version uint
        if err := rlp.DecodeBytes(data, &version); err == nil && version == mipmapVersion {
            return nil
        }
    }

    defer func() {
        if err == nil {
            var val []byte
            val, err = rlp.EncodeToBytes(mipmapVersion)
            if err == nil {
                err = db.Put([]byte("setting-mipmap-version"), val)
            }
            return
        }
    }()
    latestBlock := core.GetBlock(db, core.GetHeadBlockHash(db))
    if latestBlock == nil { // clean database
        return
    }

    tstart := time.Now()
    glog.V(logger.Info).Infoln("upgrading db log bloom bins")
    for i := uint64(0); i <= latestBlock.NumberU64(); i++ {
        hash := core.GetCanonicalHash(db, i)
        if (hash == common.Hash{}) {
            return fmt.Errorf("chain db corrupted. Could not find block %d.", i)
        }
        core.WriteMipmapBloom(db, i, core.GetBlockReceipts(db, hash))
    }
    glog.V(logger.Info).Infoln("upgrade completed in", time.Since(tstart))
    return nil
}