api.go

// Copyright 2015 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 eth

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"math/big"
	"os"
	"runtime"
	"strings"
	"sync"
	"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/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/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/rlp"
	"github.com/ethereum/go-ethereum/rpc"
	"github.com/syndtr/goleveldb/leveldb"
	"golang.org/x/net/context"
)

const defaultGas = uint64(90000)

// blockByNumber is a commonly used helper function which retrieves and returns
// the block for the given block number, capable of handling two special blocks:
// rpc.LatestBlockNumber and rpc.PendingBlockNumber. It returns nil when no block
// could be found.
func blockByNumber(m *miner.Miner, bc *core.BlockChain, blockNr rpc.BlockNumber) *types.Block {
	// Pending block is only known by the miner
	if blockNr == rpc.PendingBlockNumber {
		block, _ := m.Pending()
		return block
	}
	// Otherwise resolve and return the block
	if blockNr == rpc.LatestBlockNumber {
		return bc.CurrentBlock()
	}
	return bc.GetBlockByNumber(uint64(blockNr))
}

// stateAndBlockByNumber is a commonly used helper function which retrieves and
// returns the state and containing block for the given block number, capable of
// handling two special states: rpc.LatestBlockNumber and rpc.PendingBlockNumber.
// It returns nil when no block or state could be found.
func stateAndBlockByNumber(m *miner.Miner, bc *core.BlockChain, blockNr rpc.BlockNumber, chainDb ethdb.Database) (*state.StateDB, *types.Block, error) {
	// Pending state is only known by the miner
	if blockNr == rpc.PendingBlockNumber {
		block, state := m.Pending()
		return state, block, nil
	}
	// Otherwise resolve the block number and return its state
	block := blockByNumber(m, bc, blockNr)
	if block == nil {
		return nil, nil, nil
	}
	stateDb, err := state.New(block.Root(), chainDb)
	return stateDb, block, err
}

// PublicEthereumAPI provides an API to access Ethereum related information.
// It offers only methods that operate on public data that is freely available to anyone.
type PublicEthereumAPI struct {
	e   *Ethereum
	gpo *GasPriceOracle
}

// NewPublicEthereumAPI creates a new Ethereum protocol API.
func NewPublicEthereumAPI(e *Ethereum, gpo *GasPriceOracle) *PublicEthereumAPI {
	return &PublicEthereumAPI{e, gpo}
}

// GasPrice returns a suggestion for a gas price.
func (s *PublicEthereumAPI) GasPrice() *big.Int {
	return s.gpo.SuggestPrice()
}

// GetCompilers returns the collection of available smart contract compilers
func (s *PublicEthereumAPI) GetCompilers() ([]string, error) {
	solc, err := s.e.Solc()
	if err != nil && solc != nil {
		return []string{"Solidity"}, nil
	}

	return []string{}, nil
}

// CompileSolidity compiles the given solidity source
func (s *PublicEthereumAPI) CompileSolidity(source string) (map[string]*compiler.Contract, error) {
	solc, err := s.e.Solc()
	if err != nil {
		return nil, err
	}

	if solc == nil {
		return nil, errors.New("solc (solidity compiler) not found")
	}

	return solc.Compile(source)
}

// Etherbase is the address that mining rewards will be send to
func (s *PublicEthereumAPI) Etherbase() (common.Address, error) {
	return s.e.Etherbase()
}

// see Etherbase
func (s *PublicEthereumAPI) Coinbase() (common.Address, error) {
	return s.Etherbase()
}

// ProtocolVersion returns the current Ethereum protocol version this node supports
func (s *PublicEthereumAPI) ProtocolVersion() *rpc.HexNumber {
	return rpc.NewHexNumber(s.e.EthVersion())
}

// Hashrate returns the POW hashrate
func (s *PublicEthereumAPI) Hashrate() *rpc.HexNumber {
	return rpc.NewHexNumber(s.e.Miner().HashRate())
}

// Syncing returns false in case the node is currently not syncing with the network. It can be up to date or has not
// yet received the latest block headers from its pears. In case it is synchronizing:
// - startingBlock: block number this node started to synchronise from
// - currentBlock:  block number this node is currently importing
// - highestBlock:  block number of the highest block header this node has received from peers
// - pulledStates:  number of state entries processed until now
// - knownStates:   number of known state entries that still need to be pulled
func (s *PublicEthereumAPI) Syncing() (interface{}, error) {
	origin, current, height, pulled, known := s.e.Downloader().Progress()

	// Return not syncing if the synchronisation already completed
	if current >= height {
		return false, nil
	}
	// Otherwise gather the block sync stats
	return map[string]interface{}{
		"startingBlock": rpc.NewHexNumber(origin),
		"currentBlock":  rpc.NewHexNumber(current),
		"highestBlock":  rpc.NewHexNumber(height),
		"pulledStates":  rpc.NewHexNumber(pulled),
		"knownStates":   rpc.NewHexNumber(known),
	}, nil
}

// PublicMinerAPI provides an API to control the miner.
// It offers only methods that operate on data that pose no security risk when it is publicly accessible.
type PublicMinerAPI struct {
	e     *Ethereum
	agent *miner.RemoteAgent
}

// NewPublicMinerAPI create a new PublicMinerAPI instance.
func NewPublicMinerAPI(e *Ethereum) *PublicMinerAPI {
	agent := miner.NewRemoteAgent()
	e.Miner().Register(agent)

	return &PublicMinerAPI{e, agent}
}

// Mining returns an indication if this node is currently mining.
func (s *PublicMinerAPI) Mining() bool {
	return s.e.IsMining()
}

// SubmitWork can be used by external miner to submit their POW solution. It returns an indication if the work was
// accepted. Note, this is not an indication if the provided work was valid!
func (s *PublicMinerAPI) SubmitWork(nonce rpc.HexNumber, solution, digest common.Hash) bool {
	return s.agent.SubmitWork(nonce.Uint64(), digest, solution)
}

// GetWork returns a work package for external miner. The work package consists of 3 strings
// result[0], 32 bytes hex encoded current block header pow-hash
// result[1], 32 bytes hex encoded seed hash used for DAG
// result[2], 32 bytes hex encoded boundary condition ("target"), 2^256/difficulty
func (s *PublicMinerAPI) GetWork() ([]string, error) {
	if !s.e.IsMining() {
		if err := s.e.StartMining(0, ""); err != nil {
			return nil, err
		}
	}
	if work, err := s.agent.GetWork(); err == nil {
		return work[:], nil
	} else {
		glog.Infof("%v\n", err)
	}
	return nil, fmt.Errorf("mining not ready")
}

// SubmitHashrate can be used for remote miners to submit their hash rate. This enables the node to report the combined
// hash rate of all miners which submit work through this node. It accepts the miner hash rate and an identifier which
// must be unique between nodes.
func (s *PublicMinerAPI) SubmitHashrate(hashrate rpc.HexNumber, id common.Hash) bool {
	s.agent.SubmitHashrate(id, hashrate.Uint64())
	return true
}

// PrivateMinerAPI provides private RPC methods to control the miner.
// These methods can be abused by external users and must be considered insecure for use by untrusted users.
type PrivateMinerAPI struct {
	e *Ethereum
}

// NewPrivateMinerAPI create a new RPC service which controls the miner of this node.
func NewPrivateMinerAPI(e *Ethereum) *PrivateMinerAPI {
	return &PrivateMinerAPI{e: e}
}

// Start the miner with the given number of threads. If threads is nil the number of
// workers started is equal to the number of logical CPU's that are usable by this process.
func (s *PrivateMinerAPI) Start(threads *rpc.HexNumber) (bool, error) {
	s.e.StartAutoDAG()

	if threads == nil {
		threads = rpc.NewHexNumber(runtime.NumCPU())
	}

	err := s.e.StartMining(threads.Int(), "")
	if err == nil {
		return true, nil
	}
	return false, err
}

// Stop the miner
func (s *PrivateMinerAPI) Stop() bool {
	s.e.StopMining()
	return true
}

// SetExtra sets the extra data string that is included when this miner mines a block.
func (s *PrivateMinerAPI) SetExtra(extra string) (bool, error) {
	if err := s.e.Miner().SetExtra([]byte(extra)); err != nil {
		return false, err
	}
	return true, nil
}

// SetGasPrice sets the minimum accepted gas price for the miner.
func (s *PrivateMinerAPI) SetGasPrice(gasPrice rpc.HexNumber) bool {
	s.e.Miner().SetGasPrice(gasPrice.BigInt())
	return true
}

// SetEtherbase sets the etherbase of the miner
func (s *PrivateMinerAPI) SetEtherbase(etherbase common.Address) bool {
	s.e.SetEtherbase(etherbase)
	return true
}

// StartAutoDAG starts auto DAG generation. This will prevent the DAG generating on epoch change
// which will cause the node to stop mining during the generation process.
func (s *PrivateMinerAPI) StartAutoDAG() bool {
	s.e.StartAutoDAG()
	return true
}

// StopAutoDAG stops auto DAG generation
func (s *PrivateMinerAPI) StopAutoDAG() bool {
	s.e.StopAutoDAG()
	return true
}

// MakeDAG creates the new DAG for the given block number
func (s *PrivateMinerAPI) MakeDAG(blockNr rpc.BlockNumber) (bool, error) {
	if err := ethash.MakeDAG(uint64(blockNr.Int64()), ""); err != nil {
		return false, err
	}
	return true, nil
}

// PublicTxPoolAPI offers and API for the transaction pool. It only operates on data that is non confidential.
type PublicTxPoolAPI struct {
	e *Ethereum
}

// NewPublicTxPoolAPI creates a new tx pool service that gives information about the transaction pool.
func NewPublicTxPoolAPI(e *Ethereum) *PublicTxPoolAPI {
	return &PublicTxPoolAPI{e}
}

// Content returns the transactions contained within the transaction pool.
func (s *PublicTxPoolAPI) Content() map[string]map[string]map[string][]*RPCTransaction {
	content := map[string]map[string]map[string][]*RPCTransaction{
		"pending": make(map[string]map[string][]*RPCTransaction),
		"queued":  make(map[string]map[string][]*RPCTransaction),
	}
	pending, queue := s.e.TxPool().Content()

	// Flatten the pending transactions
	for account, batches := range pending {
		dump := make(map[string][]*RPCTransaction)
		for nonce, txs := range batches {
			nonce := fmt.Sprintf("%d", nonce)
			for _, tx := range txs {
				dump[nonce] = append(dump[nonce], newRPCPendingTransaction(tx))
			}
		}
		content["pending"][account.Hex()] = dump
	}
	// Flatten the queued transactions
	for account, batches := range queue {
		dump := make(map[string][]*RPCTransaction)
		for nonce, txs := range batches {
			nonce := fmt.Sprintf("%d", nonce)
			for _, tx := range txs {
				dump[nonce] = append(dump[nonce], newRPCPendingTransaction(tx))
			}
		}
		content["queued"][account.Hex()] = dump
	}
	return content
}

// Status returns the number of pending and queued transaction in the pool.
func (s *PublicTxPoolAPI) Status() map[string]*rpc.HexNumber {
	pending, queue := s.e.TxPool().Stats()
	return map[string]*rpc.HexNumber{
		"pending": rpc.NewHexNumber(pending),
		"queued":  rpc.NewHexNumber(queue),
	}
}

// Inspect retrieves the content of the transaction pool and flattens it into an
// easily inspectable list.
func (s *PublicTxPoolAPI) Inspect() map[string]map[string]map[string][]string {
	content := map[string]map[string]map[string][]string{
		"pending": make(map[string]map[string][]string),
		"queued":  make(map[string]map[string][]string),
	}
	pending, queue := s.e.TxPool().Content()

	// Define a formatter to flatten a transaction into a string
	var format = func(tx *types.Transaction) string {
		if to := tx.To(); to != nil {
			return fmt.Sprintf("%s: %v wei + %v × %v gas", tx.To().Hex(), tx.Value(), tx.Gas(), tx.GasPrice())
		}
		return fmt.Sprintf("contract creation: %v wei + %v × %v gas", tx.Value(), tx.Gas(), tx.GasPrice())
	}
	// Flatten the pending transactions
	for account, batches := range pending {
		dump := make(map[string][]string)
		for nonce, txs := range batches {
			nonce := fmt.Sprintf("%d", nonce)
			for _, tx := range txs {
				dump[nonce] = append(dump[nonce], format(tx))
			}
		}
		content["pending"][account.Hex()] = dump
	}
	// Flatten the queued transactions
	for account, batches := range queue {
		dump := make(map[string][]string)
		for nonce, txs := range batches {
			nonce := fmt.Sprintf("%d", nonce)
			for _, tx := range txs {
				dump[nonce] = append(dump[nonce], format(tx))
			}
		}
		content["queued"][account.Hex()] = dump
	}
	return content
}

// PublicAccountAPI provides an API to access accounts managed by this node.
// It offers only methods that can retrieve accounts.
type PublicAccountAPI struct {
	am *accounts.Manager
}

// NewPublicAccountAPI creates a new PublicAccountAPI.
func NewPublicAccountAPI(am *accounts.Manager) *PublicAccountAPI {
	return &PublicAccountAPI{am: am}
}

// Accounts returns the collection of accounts this node manages
func (s *PublicAccountAPI) Accounts() []accounts.Account {
	return s.am.Accounts()
}

// PrivateAccountAPI provides an API to access accounts managed by this node.
// It offers methods to create, (un)lock en list accounts.
type PrivateAccountAPI struct {
	am *accounts.Manager
}

// NewPrivateAccountAPI create a new PrivateAccountAPI.
func NewPrivateAccountAPI(am *accounts.Manager) *PrivateAccountAPI {
	return &PrivateAccountAPI{am}
}

// ListAccounts will return a list of addresses for accounts this node manages.
func (s *PrivateAccountAPI) ListAccounts() []common.Address {
	accounts := s.am.Accounts()
	addresses := make([]common.Address, len(accounts))
	for i, acc := range accounts {
		addresses[i] = acc.Address
	}
	return addresses
}

// NewAccount will create a new account and returns the address for the new account.
func (s *PrivateAccountAPI) NewAccount(password string) (common.Address, error) {
	acc, err := s.am.NewAccount(password)
	if err == nil {
		return acc.Address, nil
	}
	return common.Address{}, err
}

// UnlockAccount will unlock the account associated with the given address with
// the given password for duration seconds. If duration is nil it will use a
// default of 300 seconds. It returns an indication if the account was unlocked.
func (s *PrivateAccountAPI) UnlockAccount(addr common.Address, password string, duration *rpc.HexNumber) (bool, error) {
	if duration == nil {
		duration = rpc.NewHexNumber(300)
	}
	a := accounts.Account{Address: addr}
	d := time.Duration(duration.Int64()) * time.Second
	if err := s.am.TimedUnlock(a, password, d); err != nil {
		return false, err
	}
	return true, nil
}

// LockAccount will lock the account associated with the given address when it's unlocked.
func (s *PrivateAccountAPI) LockAccount(addr common.Address) bool {
	return s.am.Lock(addr) == nil
}

// PublicBlockChainAPI provides an API to access the Ethereum blockchain.
// It offers only methods that operate on public data that is freely available to anyone.
type PublicBlockChainAPI struct {
	config                  *core.ChainConfig
	bc                      *core.BlockChain
	chainDb                 ethdb.Database
	eventMux                *event.TypeMux
	muNewBlockSubscriptions sync.Mutex                             // protects newBlocksSubscriptions
	newBlockSubscriptions   map[string]func(core.ChainEvent) error // callbacks for new block subscriptions
	am                      *accounts.Manager
	miner                   *miner.Miner
	gpo                     *GasPriceOracle
}

// NewPublicBlockChainAPI creates a new Etheruem blockchain API.
func NewPublicBlockChainAPI(config *core.ChainConfig, bc *core.BlockChain, m *miner.Miner, chainDb ethdb.Database, gpo *GasPriceOracle, eventMux *event.TypeMux, am *accounts.Manager) *PublicBlockChainAPI {
	api := &PublicBlockChainAPI{
		config:   config,
		bc:       bc,
		miner:    m,
		chainDb:  chainDb,
		eventMux: eventMux,
		am:       am,
		newBlockSubscriptions: make(map[string]func(core.ChainEvent) error),
		gpo: gpo,
	}

	go api.subscriptionLoop()

	return api
}

// subscriptionLoop reads events from the global event mux and creates notifications for the matched subscriptions.
func (s *PublicBlockChainAPI) subscriptionLoop() {
	sub := s.eventMux.Subscribe(core.ChainEvent{})
	for event := range sub.Chan() {
		if chainEvent, ok := event.Data.(core.ChainEvent); ok {
			s.muNewBlockSubscriptions.Lock()
			for id, notifyOf := range s.newBlockSubscriptions {
				if notifyOf(chainEvent) == rpc.ErrNotificationNotFound {
					delete(s.newBlockSubscriptions, id)
				}
			}
			s.muNewBlockSubscriptions.Unlock()
		}
	}
}

// BlockNumber returns the block number of the chain head.
func (s *PublicBlockChainAPI) BlockNumber() *big.Int {
	return s.bc.CurrentHeader().Number
}

// GetBalance returns the amount of wei for the given address in the state of the
// given block number. The rpc.LatestBlockNumber and rpc.PendingBlockNumber meta
// block numbers are also allowed.
func (s *PublicBlockChainAPI) GetBalance(address common.Address, blockNr rpc.BlockNumber) (*big.Int, error) {
	state, _, err := stateAndBlockByNumber(s.miner, s.bc, blockNr, s.chainDb)
	if state == nil || err != nil {
		return nil, err
	}
	return state.GetBalance(address), nil
}

// GetBlockByNumber returns the requested block. When blockNr is -1 the chain head is returned. When fullTx is true all
// transactions in the block are returned in full detail, otherwise only the transaction hash is returned.
func (s *PublicBlockChainAPI) GetBlockByNumber(blockNr rpc.BlockNumber, fullTx bool) (map[string]interface{}, error) {
	if block := blockByNumber(s.miner, s.bc, blockNr); block != nil {
		response, err := s.rpcOutputBlock(block, true, fullTx)
		if err == nil && blockNr == rpc.PendingBlockNumber {
			// Pending blocks need to nil out a few fields
			for _, field := range []string{"hash", "nonce", "logsBloom", "miner"} {
				response[field] = nil
			}
		}
		return response, err
	}
	return nil, nil
}

// GetBlockByHash returns the requested block. When fullTx is true all transactions in the block are returned in full
// detail, otherwise only the transaction hash is returned.
func (s *PublicBlockChainAPI) GetBlockByHash(blockHash common.Hash, fullTx bool) (map[string]interface{}, error) {
	if block := s.bc.GetBlock(blockHash); block != nil {
		return s.rpcOutputBlock(block, true, fullTx)
	}
	return nil, nil
}

// GetUncleByBlockNumberAndIndex returns the uncle block for the given block hash and index. When fullTx is true
// all transactions in the block are returned in full detail, otherwise only the transaction hash is returned.
func (s *PublicBlockChainAPI) GetUncleByBlockNumberAndIndex(blockNr rpc.BlockNumber, index rpc.HexNumber) (map[string]interface{}, error) {
	if block := blockByNumber(s.miner, s.bc, blockNr); block != nil {
		uncles := block.Uncles()
		if index.Int() < 0 || index.Int() >= len(uncles) {
			glog.V(logger.Debug).Infof("uncle block on index %d not found for block #%d", index.Int(), blockNr)
			return nil, nil
		}
		block = types.NewBlockWithHeader(uncles[index.Int()])
		return s.rpcOutputBlock(block, false, false)
	}
	return nil, nil
}

// GetUncleByBlockHashAndIndex returns the uncle block for the given block hash and index. When fullTx is true
// all transactions in the block are returned in full detail, otherwise only the transaction hash is returned.
func (s *PublicBlockChainAPI) GetUncleByBlockHashAndIndex(blockHash common.Hash, index rpc.HexNumber) (map[string]interface{}, error) {
	if block := s.bc.GetBlock(blockHash); block != nil {
		uncles := block.Uncles()
		if index.Int() < 0 || index.Int() >= len(uncles) {
			glog.V(logger.Debug).Infof("uncle block on index %d not found for block %s", index.Int(), blockHash.Hex())
			return nil, nil
		}
		block = types.NewBlockWithHeader(uncles[index.Int()])
		return s.rpcOutputBlock(block, false, false)
	}
	return nil, nil
}

// GetUncleCountByBlockNumber returns number of uncles in the block for the given block number
func (s *PublicBlockChainAPI) GetUncleCountByBlockNumber(blockNr rpc.BlockNumber) *rpc.HexNumber {
	if block := blockByNumber(s.miner, s.bc, blockNr); block != nil {
		return rpc.NewHexNumber(len(block.Uncles()))
	}
	return nil
}

// GetUncleCountByBlockHash returns number of uncles in the block for the given block hash
func (s *PublicBlockChainAPI) GetUncleCountByBlockHash(blockHash common.Hash) *rpc.HexNumber {
	if block := s.bc.GetBlock(blockHash); block != nil {
		return rpc.NewHexNumber(len(block.Uncles()))
	}
	return nil
}

// NewBlocksArgs allows the user to specify if the returned block should include transactions and in which format.
type NewBlocksArgs struct {
	IncludeTransactions bool `json:"includeTransactions"`
	TransactionDetails  bool `json:"transactionDetails"`
}

// NewBlocks triggers a new block event each time a block is appended to the chain. It accepts an argument which allows
// the caller to specify whether the output should contain transactions and in what format.
func (s *PublicBlockChainAPI) NewBlocks(ctx context.Context, args NewBlocksArgs) (rpc.Subscription, error) {
	notifier, supported := ctx.Value(rpc.NotifierContextKey).(rpc.Notifier)
	if !supported {
		return nil, rpc.ErrNotificationsUnsupported
	}

	// create a subscription that will remove itself when unsubscribed/cancelled
	subscription, err := notifier.NewSubscription(func(subId string) {
		s.muNewBlockSubscriptions.Lock()
		delete(s.newBlockSubscriptions, subId)
		s.muNewBlockSubscriptions.Unlock()
	})

	if err != nil {
		return nil, err
	}

	// add a callback that is called on chain events which will format the block and notify the client
	s.muNewBlockSubscriptions.Lock()
	s.newBlockSubscriptions[subscription.ID()] = func(e core.ChainEvent) error {
		if notification, err := s.rpcOutputBlock(e.Block, args.IncludeTransactions, args.TransactionDetails); err == nil {
			return subscription.Notify(notification)
		} else {
			glog.V(logger.Warn).Info("unable to format block %v\n", err)
		}
		return nil
	}
	s.muNewBlockSubscriptions.Unlock()

	return subscription, nil
}

// GetCode returns the code stored at the given address in the state for the given block number.
func (s *PublicBlockChainAPI) GetCode(address common.Address, blockNr rpc.BlockNumber) (string, error) {
	state, _, err := stateAndBlockByNumber(s.miner, s.bc, blockNr, s.chainDb)
	if state == nil || err != nil {
		return "", err
	}
	res := state.GetCode(address)
	if len(res) == 0 { // backwards compatibility
		return "0x", nil
	}
	return common.ToHex(res), nil
}

// GetStorageAt returns the storage from the state at the given address, key and
// block number. The rpc.LatestBlockNumber and rpc.PendingBlockNumber meta block
// numbers are also allowed.
func (s *PublicBlockChainAPI) GetStorageAt(address common.Address, key string, blockNr rpc.BlockNumber) (string, error) {
	state, _, err := stateAndBlockByNumber(s.miner, s.bc, blockNr, s.chainDb)
	if state == nil || err != nil {
		return "0x", err
	}
	return state.GetState(address, common.HexToHash(key)).Hex(), nil
}

// callmsg is the message type used for call transactions.
type callmsg struct {
	from          *state.StateObject
	to            *common.Address
	gas, gasPrice *big.Int
	value         *big.Int
	data          []byte
}

// accessor boilerplate to implement core.Message
func (m callmsg) From() (common.Address, error)         { return m.from.Address(), nil }
func (m callmsg) FromFrontier() (common.Address, error) { return m.from.Address(), nil }
func (m callmsg) Nonce() uint64                         { return m.from.Nonce() }
func (m callmsg) To() *common.Address                   { return m.to }
func (m callmsg) GasPrice() *big.Int                    { return m.gasPrice }
func (m callmsg) Gas() *big.Int                         { return m.gas }
func (m callmsg) Value() *big.Int                       { return m.value }
func (m callmsg) Data() []byte                          { return m.data }

type CallArgs struct {
	From     common.Address  `json:"from"`
	To       *common.Address `json:"to"`
	Gas      *rpc.HexNumber  `json:"gas"`
	GasPrice *rpc.HexNumber  `json:"gasPrice"`
	Value    rpc.HexNumber   `json:"value"`
	Data     string          `json:"data"`
}

func (s *PublicBlockChainAPI) doCall(args CallArgs, blockNr rpc.BlockNumber) (string, *big.Int, error) {
	// Fetch the state associated with the block number
	stateDb, block, err := stateAndBlockByNumber(s.miner, s.bc, blockNr, s.chainDb)
	if stateDb == nil || err != nil {
		return "0x", nil, err
	}
	stateDb = stateDb.Copy()

	// Retrieve the account state object to interact with
	var from *state.StateObject
	if args.From == (common.Address{}) {
		accounts := s.am.Accounts()
		if len(accounts) == 0 {
			from = stateDb.GetOrNewStateObject(common.Address{})
		} else {
			from = stateDb.GetOrNewStateObject(accounts[0].Address)
		}
	} else {
		from = stateDb.GetOrNewStateObject(args.From)
	}
	from.SetBalance(common.MaxBig)

	// Assemble the CALL invocation
	msg := callmsg{
		from:     from,
		to:       args.To,
		gas:      args.Gas.BigInt(),
		gasPrice: args.GasPrice.BigInt(),
		value:    args.Value.BigInt(),
		data:     common.FromHex(args.Data),
	}
	if msg.gas == nil {
		msg.gas = big.NewInt(50000000)
	}
	if msg.gasPrice == nil {
		msg.gasPrice = s.gpo.SuggestPrice()
	}

	// Execute the call and return
	vmenv := core.NewEnv(stateDb, s.config, s.bc, msg, block.Header(), s.config.VmConfig)
	gp := new(core.GasPool).AddGas(common.MaxBig)

	res, requiredGas, _, err := core.NewStateTransition(vmenv, msg, gp).TransitionDb()
	if len(res) == 0 { // backwards compatibility
		return "0x", requiredGas, err
	}
	return common.ToHex(res), requiredGas, err
}

// Call executes the given transaction on the state for the given block number.
// It doesn't make and changes in the state/blockchain and is useful to execute and retrieve values.
func (s *PublicBlockChainAPI) Call(args CallArgs, blockNr rpc.BlockNumber) (string, error) {
	result, _, err := s.doCall(args, blockNr)
	return result, err
}

// EstimateGas returns an estimate of the amount of gas needed to execute the given transaction.
func (s *PublicBlockChainAPI) EstimateGas(args CallArgs) (*rpc.HexNumber, error) {
	_, gas, err := s.doCall(args, rpc.PendingBlockNumber)
	return rpc.NewHexNumber(gas), err
}

// rpcOutputBlock converts the given block to the RPC output which depends on fullTx. If inclTx is true transactions are
// returned. When fullTx is true the returned block contains full transaction details, otherwise it will only contain
// transaction hashes.
func (s *PublicBlockChainAPI) rpcOutputBlock(b *types.Block, inclTx bool, fullTx bool) (map[string]interface{}, error) {
	fields := map[string]interface{}{
		"number":           rpc.NewHexNumber(b.Number()),
		"hash":             b.Hash(),
		"parentHash":       b.ParentHash(),
		"nonce":            b.Header().Nonce,
		"sha3Uncles":       b.UncleHash(),
		"logsBloom":        b.Bloom(),
		"stateRoot":        b.Root(),
		"miner":            b.Coinbase(),
		"difficulty":       rpc.NewHexNumber(b.Difficulty()),
		"totalDifficulty":  rpc.NewHexNumber(s.bc.GetTd(b.Hash())),
		"extraData":        fmt.Sprintf("0x%x", b.Extra()),
		"size":             rpc.NewHexNumber(b.Size().Int64()),
		"gasLimit":         rpc.NewHexNumber(b.GasLimit()),
		"gasUsed":          rpc.NewHexNumber(b.GasUsed()),
		"timestamp":        rpc.NewHexNumber(b.Time()),
		"transactionsRoot": b.TxHash(),
		"receiptRoot":      b.ReceiptHash(),
	}

	if inclTx {
		formatTx := func(tx *types.Transaction) (interface{}, error) {
			return tx.Hash(), nil
		}

		if fullTx {
			formatTx = func(tx *types.Transaction) (interface{}, error) {
				return newRPCTransaction(b, tx.Hash())
			}
		}

		txs := b.Transactions()
		transactions := make([]interface{}, len(txs))
		var err error
		for i, tx := range b.Transactions() {
			if transactions[i], err = formatTx(tx); err != nil {
				return nil, err
			}
		}
		fields["transactions"] = transactions
	}

	uncles := b.Uncles()
	uncleHashes := make([]common.Hash, len(uncles))
	for i, uncle := range uncles {
		uncleHashes[i] = uncle.Hash()
	}
	fields["uncles"] = uncleHashes

	return fields, nil
}

// RPCTransaction represents a transaction that will serialize to the RPC representation of a transaction
type RPCTransaction struct {
	BlockHash        common.Hash     `json:"blockHash"`
	BlockNumber      *rpc.HexNumber  `json:"blockNumber"`
	From             common.Address  `json:"from"`
	Gas              *rpc.HexNumber  `json:"gas"`
	GasPrice         *rpc.HexNumber  `json:"gasPrice"`
	Hash             common.Hash     `json:"hash"`
	Input            string          `json:"input"`
	Nonce            *rpc.HexNumber  `json:"nonce"`
	To               *common.Address `json:"to"`
	TransactionIndex *rpc.HexNumber  `json:"transactionIndex"`
	Value            *rpc.HexNumber  `json:"value"`
}

// newRPCPendingTransaction returns a pending transaction that will serialize to the RPC representation
func newRPCPendingTransaction(tx *types.Transaction) *RPCTransaction {
	from, _ := tx.FromFrontier()

	return &RPCTransaction{
		From:     from,
		Gas:      rpc.NewHexNumber(tx.Gas()),
		GasPrice: rpc.NewHexNumber(tx.GasPrice()),
		Hash:     tx.Hash(),
		Input:    fmt.Sprintf("0x%x", tx.Data()),
		Nonce:    rpc.NewHexNumber(tx.Nonce()),
		To:       tx.To(),
		Value:    rpc.NewHexNumber(tx.Value()),
	}
}

// newRPCTransaction returns a transaction that will serialize to the RPC representation.
func newRPCTransactionFromBlockIndex(b *types.Block, txIndex int) (*RPCTransaction, error) {
	if txIndex >= 0 && txIndex < len(b.Transactions()) {
		tx := b.Transactions()[txIndex]
		from, err := tx.FromFrontier()
		if err != nil {
			return nil, err
		}

		return &RPCTransaction{
			BlockHash:        b.Hash(),
			BlockNumber:      rpc.NewHexNumber(b.Number()),
			From:             from,
			Gas:              rpc.NewHexNumber(tx.Gas()),
			GasPrice:         rpc.NewHexNumber(tx.GasPrice()),
			Hash:             tx.Hash(),
			Input:            fmt.Sprintf("0x%x", tx.Data()),
			Nonce:            rpc.NewHexNumber(tx.Nonce()),
			To:               tx.To(),
			TransactionIndex: rpc.NewHexNumber(txIndex),
			Value:            rpc.NewHexNumber(tx.Value()),
		}, nil
	}

	return nil, nil
}

// newRPCTransaction returns a transaction that will serialize to the RPC representation.
func newRPCTransaction(b *types.Block, txHash common.Hash) (*RPCTransaction, error) {
	for idx, tx := range b.Transactions() {
		if tx.Hash() == txHash {
			return newRPCTransactionFromBlockIndex(b, idx)
		}
	}

	return nil, nil
}

// PublicTransactionPoolAPI exposes methods for the RPC interface
type PublicTransactionPoolAPI struct {
	eventMux        *event.TypeMux
	chainDb         ethdb.Database
	gpo             *GasPriceOracle
	bc              *core.BlockChain
	miner           *miner.Miner
	am              *accounts.Manager
	txPool          *core.TxPool
	txMu            sync.Mutex
	muPendingTxSubs sync.Mutex
	pendingTxSubs   map[string]rpc.Subscription
}

// NewPublicTransactionPoolAPI creates a new RPC service with methods specific for the transaction pool.
func NewPublicTransactionPoolAPI(e *Ethereum, gpo *GasPriceOracle) *PublicTransactionPoolAPI {
	api := &PublicTransactionPoolAPI{
		eventMux:      e.EventMux(),
		gpo:           gpo,
		chainDb:       e.ChainDb(),
		bc:            e.BlockChain(),
		am:            e.AccountManager(),
		txPool:        e.TxPool(),
		miner:         e.Miner(),
		pendingTxSubs: make(map[string]rpc.Subscription),
	}

	go api.subscriptionLoop()

	return api
}

// subscriptionLoop listens for events on the global event mux and creates notifications for subscriptions.
func (s *PublicTransactionPoolAPI) subscriptionLoop() {
	sub := s.eventMux.Subscribe(core.TxPreEvent{})
	for event := range sub.Chan() {
		tx := event.Data.(core.TxPreEvent)
		if from, err := tx.Tx.FromFrontier(); err == nil {
			if s.am.HasAddress(from) {
				s.muPendingTxSubs.Lock()
				for id, sub := range s.pendingTxSubs {
					if sub.Notify(tx.Tx.Hash()) == rpc.ErrNotificationNotFound {
						delete(s.pendingTxSubs, id)
					}
				}
				s.muPendingTxSubs.Unlock()
			}
		}
	}
}

func getTransaction(chainDb ethdb.Database, txPool *core.TxPool, txHash common.Hash) (*types.Transaction, bool, error) {
	txData, err := chainDb.Get(txHash.Bytes())
	isPending := false
	tx := new(types.Transaction)

	if err == nil && len(txData) > 0 {
		if err := rlp.DecodeBytes(txData, tx); err != nil {
			return nil, isPending, err
		}
	} else {
		// pending transaction?
		tx = txPool.GetTransaction(txHash)
		isPending = true
	}

	return tx, isPending, nil
}

// GetBlockTransactionCountByNumber returns the number of transactions in the block with the given block number.
func (s *PublicTransactionPoolAPI) GetBlockTransactionCountByNumber(blockNr rpc.BlockNumber) *rpc.HexNumber {
	if block := blockByNumber(s.miner, s.bc, blockNr); block != nil {
		return rpc.NewHexNumber(len(block.Transactions()))
	}
	return nil
}

// GetBlockTransactionCountByHash returns the number of transactions in the block with the given hash.
func (s *PublicTransactionPoolAPI) GetBlockTransactionCountByHash(blockHash common.Hash) *rpc.HexNumber {
	if block := s.bc.GetBlock(blockHash); block != nil {
		return rpc.NewHexNumber(len(block.Transactions()))
	}
	return nil
}

// GetTransactionByBlockNumberAndIndex returns the transaction for the given block number and index.
func (s *PublicTransactionPoolAPI) GetTransactionByBlockNumberAndIndex(blockNr rpc.BlockNumber, index rpc.HexNumber) (*RPCTransaction, error) {
	if block := blockByNumber(s.miner, s.bc, blockNr); block != nil {
		return newRPCTransactionFromBlockIndex(block, index.Int())
	}
	return nil, nil
}

// GetTransactionByBlockHashAndIndex returns the transaction for the given block hash and index.
func (s *PublicTransactionPoolAPI) GetTransactionByBlockHashAndIndex(blockHash common.Hash, index rpc.HexNumber) (*RPCTransaction, error) {
	if block := s.bc.GetBlock(blockHash); block != nil {
		return newRPCTransactionFromBlockIndex(block, index.Int())
	}
	return nil, nil
}

// GetTransactionCount returns the number of transactions the given address has sent for the given block number
func (s *PublicTransactionPoolAPI) GetTransactionCount(address common.Address, blockNr rpc.BlockNumber) (*rpc.HexNumber, error) {
	state, _, err := stateAndBlockByNumber(s.miner, s.bc, blockNr, s.chainDb)
	if state == nil || err != nil {
		return nil, err
	}
	return rpc.NewHexNumber(state.GetNonce(address)), nil
}

// getTransactionBlockData fetches the meta data for the given transaction from the chain database. This is useful to
// retrieve block information for a hash. It returns the block hash, block index and transaction index.
func getTransactionBlockData(chainDb ethdb.Database, txHash common.Hash) (common.Hash, uint64, uint64, error) {
	var txBlock struct {
		BlockHash  common.Hash
		BlockIndex uint64
		Index      uint64
	}

	blockData, err := chainDb.Get(append(txHash.Bytes(), 0x0001))
	if err != nil {
		return common.Hash{}, uint64(0), uint64(0), err
	}

	reader := bytes.NewReader(blockData)