path: root/eth/api.go

// Copyright 2015 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

import (
    "bytes"
    "compress/gzip"
    "context"
    "fmt"
    "io"
    "io/ioutil"
    "math/big"
    "os"
    "strings"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/common/hexutil"
    "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/internal/ethapi"
    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/miner"
    "github.com/ethereum/go-ethereum/params"
    "github.com/ethereum/go-ethereum/rlp"
    "github.com/ethereum/go-ethereum/rpc"
    "github.com/ethereum/go-ethereum/trie"
)

const defaultTraceTimeout = 5 * time.Second

// PublicEthereumAPI provides an API to access Ethereum full node-related
// information.
type PublicEthereumAPI struct {
    e *Ethereum
}

// NewPublicEthereumAPI creates a new Ethereum protocol API for full nodes.
func NewPublicEthereumAPI(e *Ethereum) *PublicEthereumAPI {
    return &PublicEthereumAPI{e}
}

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

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

// Hashrate returns the POW hashrate
func (api *PublicEthereumAPI) Hashrate() hexutil.Uint64 {
    return hexutil.Uint64(api.e.Miner().HashRate())
}

// 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.BlockChain(), e.Engine())
    e.Miner().Register(agent)

    return &PublicMinerAPI{e, agent}
}

// Mining returns an indication if this node is currently mining.
func (api *PublicMinerAPI) Mining() bool {
    return api.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 (api *PublicMinerAPI) SubmitWork(nonce types.BlockNonce, solution, digest common.Hash) bool {
    return api.agent.SubmitWork(nonce, 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 (api *PublicMinerAPI) GetWork() ([3]string, error) {
    if !api.e.IsMining() {
        if err := api.e.StartMining(false); err != nil {
            return [3]string{}, err
        }
    }
    work, err := api.agent.GetWork()
    if err != nil {
        return work, fmt.Errorf("mining not ready: %v", err)
    }
    return work, nil
}

// 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 (api *PublicMinerAPI) SubmitHashrate(hashrate hexutil.Uint64, id common.Hash) bool {
    api.agent.SubmitHashrate(id, uint64(hashrate))
    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 CPUs that are usable by
// this process. If mining is already running, this method adjust the number of
// threads allowed to use.
func (api *PrivateMinerAPI) Start(threads *int) error {
    // Set the number of threads if the seal engine supports it
    if threads == nil {
        threads = new(int)
    } else if *threads == 0 {
        *threads = -1 // Disable the miner from within
    }
    type threaded interface {
        SetThreads(threads int)
    }
    if th, ok := api.e.engine.(threaded); ok {
        log.Info("Updated mining threads", "threads", *threads)
        th.SetThreads(*threads)
    }
    // Start the miner and return
    if !api.e.IsMining() {
        // Propagate the initial price point to the transaction pool
        api.e.lock.RLock()
        price := api.e.gasPrice
        api.e.lock.RUnlock()

        api.e.txPool.SetGasPrice(price)
        return api.e.StartMining(true)
    }
    return nil
}

// Stop the miner
func (api *PrivateMinerAPI) Stop() bool {
    type threaded interface {
        SetThreads(threads int)
    }
    if th, ok := api.e.engine.(threaded); ok {
        th.SetThreads(-1)
    }
    api.e.StopMining()
    return true
}

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

// SetGasPrice sets the minimum accepted gas price for the miner.
func (api *PrivateMinerAPI) SetGasPrice(gasPrice hexutil.Big) bool {
    api.e.lock.Lock()
    api.e.gasPrice = (*big.Int)(&gasPrice)
    api.e.lock.Unlock()

    api.e.txPool.SetGasPrice((*big.Int)(&gasPrice))
    return true
}

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

// GetHashrate returns the current hashrate of the miner.
func (api *PrivateMinerAPI) GetHashrate() uint64 {
    return uint64(api.e.miner.HashRate())
}

// PrivateAdminAPI is the collection of Ethereum full node-related APIs
// exposed over the private admin endpoint.
type PrivateAdminAPI struct {
    eth *Ethereum
}

// NewPrivateAdminAPI creates a new API definition for the full node private
// admin methods of the Ethereum service.
func NewPrivateAdminAPI(eth *Ethereum) *PrivateAdminAPI {
    return &PrivateAdminAPI{eth: eth}
}

// ExportChain exports the current blockchain into a local file.
func (api *PrivateAdminAPI) ExportChain(file string) (bool, error) {
    // Make sure we can create the file to export into
    out, err := os.OpenFile(file, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, os.ModePerm)
    if err != nil {
        return false, err
    }
    defer out.Close()

    var writer io.Writer = out
    if strings.HasSuffix(file, ".gz") {
        writer = gzip.NewWriter(writer)
        defer writer.(*gzip.Writer).Close()
    }

    // Export the blockchain
    if err := api.eth.BlockChain().Export(writer); err != nil {
        return false, err
    }
    return true, nil
}

func hasAllBlocks(chain *core.BlockChain, bs []*types.Block) bool {
    for _, b := range bs {
        if !chain.HasBlock(b.Hash(), b.NumberU64()) {
            return false
        }
    }

    return true
}

// ImportChain imports a blockchain from a local file.
func (api *PrivateAdminAPI) ImportChain(file string) (bool, error) {
    // Make sure the can access the file to import
    in, err := os.Open(file)
    if err != nil {
        return false, err
    }
    defer in.Close()

    var reader io.Reader = in
    if strings.HasSuffix(file, ".gz") {
        if reader, err = gzip.NewReader(reader); err != nil {
            return false, err
        }
    }

    // Run actual the import in pre-configured batches
    stream := rlp.NewStream(reader, 0)

    blocks, index := make([]*types.Block, 0, 2500), 0
    for batch := 0; ; batch++ {
        // Load a batch of blocks from the input file
        for len(blocks) < cap(blocks) {
            block := new(types.Block)
            if err := stream.Decode(block); err == io.EOF {
                break
            } else if err != nil {
                return false, fmt.Errorf("block %d: failed to parse: %v", index, err)
            }
            blocks = append(blocks, block)
            index++
        }
        if len(blocks) == 0 {
            break
        }

        if hasAllBlocks(api.eth.BlockChain(), blocks) {
            blocks = blocks[:0]
            continue
        }
        // Import the batch and reset the buffer
        if _, err := api.eth.BlockChain().InsertChain(blocks); err != nil {
            return false, fmt.Errorf("batch %d: failed to insert: %v", batch, err)
        }
        blocks = blocks[:0]
    }
    return true, nil
}

// PublicDebugAPI is the collection of Ethereum full node APIs exposed
// over the public debugging endpoint.
type PublicDebugAPI struct {
    eth *Ethereum
}

// NewPublicDebugAPI creates a new API definition for the full node-
// related public debug methods of the Ethereum service.
func NewPublicDebugAPI(eth *Ethereum) *PublicDebugAPI {
    return &PublicDebugAPI{eth: eth}
}

// DumpBlock retrieves the entire state of the database at a given block.
func (api *PublicDebugAPI) DumpBlock(blockNr rpc.BlockNumber) (state.Dump, error) {
    if blockNr == rpc.PendingBlockNumber {
        // If we're dumping the pending state, we need to request
        // both the pending block as well as the pending state from
        // the miner and operate on those
        _, stateDb := api.eth.miner.Pending()
        return stateDb.RawDump(), nil
    }
    var block *types.Block
    if blockNr == rpc.LatestBlockNumber {
        block = api.eth.blockchain.CurrentBlock()
    } else {
        block = api.eth.blockchain.GetBlockByNumber(uint64(blockNr))
    }
    if block == nil {
        return state.Dump{}, fmt.Errorf("block #%d not found", blockNr)
    }
    stateDb, err := api.eth.BlockChain().StateAt(block.Root())
    if err != nil {
        return state.Dump{}, err
    }
    return stateDb.RawDump(), nil
}

// PrivateDebugAPI is the collection of Ethereum full node APIs exposed over
// the private debugging endpoint.
type PrivateDebugAPI struct {
    config *params.ChainConfig
    eth    *Ethereum
}

// NewPrivateDebugAPI creates a new API definition for the full node-related
// private debug methods of the Ethereum service.
func NewPrivateDebugAPI(config *params.ChainConfig, eth *Ethereum) *PrivateDebugAPI {
    return &PrivateDebugAPI{config: config, eth: eth}
}

// BlockTraceResult is the returned value when replaying a block to check for
// consensus results and full VM trace logs for all included transactions.
type BlockTraceResult struct {
    Validated  bool                  `json:"validated"`
    StructLogs []ethapi.StructLogRes `json:"structLogs"`
    Error      string                `json:"error"`
}

// TraceArgs holds extra parameters to trace functions
type TraceArgs struct {
    *vm.LogConfig
    Tracer  *string
    Timeout *string
}

// TraceBlock processes the given block'api RLP but does not import the block in to
// the chain.
func (api *PrivateDebugAPI) TraceBlock(blockRlp []byte, config *vm.LogConfig) BlockTraceResult {
    var block types.Block
    err := rlp.Decode(bytes.NewReader(blockRlp), &block)
    if err != nil {
        return BlockTraceResult{Error: fmt.Sprintf("could not decode block: %v", err)}
    }

    validated, logs, err := api.traceBlock(&block, config)
    return BlockTraceResult{
        Validated:  validated,
        StructLogs: ethapi.FormatLogs(logs),
        Error:      formatError(err),
    }
}

// TraceBlockFromFile loads the block'api RLP from the given file name and attempts to
// process it but does not import the block in to the chain.
func (api *PrivateDebugAPI) TraceBlockFromFile(file string, config *vm.LogConfig) BlockTraceResult {
    blockRlp, err := ioutil.ReadFile(file)
    if err != nil {
        return BlockTraceResult{Error: fmt.Sprintf("could not read file: %v", err)}
    }
    return api.TraceBlock(blockRlp, config)
}

// TraceBlockByNumber processes the block by canonical block number.
func (api *PrivateDebugAPI) TraceBlockByNumber(blockNr rpc.BlockNumber, config *vm.LogConfig) BlockTraceResult {
    // Fetch the block that we aim to reprocess
    var block *types.Block
    switch blockNr {
    case rpc.PendingBlockNumber:
        // Pending block is only known by the miner
        block = api.eth.miner.PendingBlock()
    case rpc.LatestBlockNumber:
        block = api.eth.blockchain.CurrentBlock()
    default:
        block = api.eth.blockchain.GetBlockByNumber(uint64(blockNr))
    }

    if block == nil {
        return BlockTraceResult{Error: fmt.Sprintf("block #%d not found", blockNr)}
    }

    validated, logs, err := api.traceBlock(block, config)
    return BlockTraceResult{
        Validated:  validated,
        StructLogs: ethapi.FormatLogs(logs),
        Error:      formatError(err),
    }
}

// TraceBlockByHash processes the block by hash.
func (api *PrivateDebugAPI) TraceBlockByHash(hash common.Hash, config *vm.LogConfig) BlockTraceResult {
    // Fetch the block that we aim to reprocess
    block := api.eth.BlockChain().GetBlockByHash(hash)
    if block == nil {
        return BlockTraceResult{Error: fmt.Sprintf("block #%x not found", hash)}
    }

    validated, logs, err := api.traceBlock(block, config)
    return BlockTraceResult{
        Validated:  validated,
        StructLogs: ethapi.FormatLogs(logs),
        Error:      formatError(err),
    }
}

// traceBlock processes the given block but does not save the state.
func (api *PrivateDebugAPI) traceBlock(block *types.Block, logConfig *vm.LogConfig) (bool, []vm.StructLog, error) {
    // Validate and reprocess the block
    var (
        blockchain = api.eth.BlockChain()
        validator  = blockchain.Validator()
        processor  = blockchain.Processor()
    )

    structLogger := vm.NewStructLogger(logConfig)

    config := vm.Config{
        Debug:  true,
        Tracer: structLogger,
    }
    if err := api.eth.engine.VerifyHeader(blockchain, block.Header(), true); err != nil {
        return false, structLogger.StructLogs(), err
    }
    statedb, err := blockchain.StateAt(blockchain.GetBlock(block.ParentHash(), block.NumberU64()-1).Root())
    if err != nil {
        return false, structLogger.StructLogs(), err
    }

    receipts, _, usedGas, err := processor.Process(block, statedb, config)
    if err != nil {
        return false, structLogger.StructLogs(), err
    }
    if err := validator.ValidateState(block, blockchain.GetBlock(block.ParentHash(), block.NumberU64()-1), statedb, receipts, usedGas); err != nil {
        return false, structLogger.StructLogs(), err
    }
    return true, structLogger.StructLogs(), nil
}

// formatError formats a Go error into either an empty string or the data content
// of the error itself.
func formatError(err error) string {
    if err == nil {
        return ""
    }
    return err.Error()
}

type timeoutError struct{}

func (t *timeoutError) Error() string {
    return "Execution time exceeded"
}

// TraceTransaction returns the structured logs created during the execution of EVM
// and returns them as a JSON object.
func (api *PrivateDebugAPI) TraceTransaction(ctx context.Context, txHash common.Hash, config *TraceArgs) (interface{}, error) {
    var tracer vm.Tracer
    if config != nil && config.Tracer != nil {
        timeout := defaultTraceTimeout
        if config.Timeout != nil {
            var err error
            if timeout, err = time.ParseDuration(*config.Timeout); err != nil {
                return nil, err
            }
        }

        var err error
        if tracer, err = ethapi.NewJavascriptTracer(*config.Tracer); err != nil {
            return nil, err
        }

        // Handle timeouts and RPC cancellations
        deadlineCtx, cancel := context.WithTimeout(ctx, timeout)
        go func() {
            <-deadlineCtx.Done()
            tracer.(*ethapi.JavascriptTracer).Stop(&timeoutError{})
        }()
        defer cancel()
    } else if config == nil {
        tracer = vm.NewStructLogger(nil)
    } else {
        tracer = vm.NewStructLogger(config.LogConfig)
    }

    // Retrieve the tx from the chain and the containing block
    tx, blockHash, _, txIndex := core.GetTransaction(api.eth.ChainDb(), txHash)
    if tx == nil {
        return nil, fmt.Errorf("transaction %x not found", txHash)
    }
    msg, context, statedb, err := api.computeTxEnv(blockHash, int(txIndex))
    if err != nil {
        return nil, err
    }

    // Run the transaction with tracing enabled.
    vmenv := vm.NewEVM(context, statedb, api.config, vm.Config{Debug: true, Tracer: tracer})
    ret, gas, failed, err := core.ApplyMessage(vmenv, msg, new(core.GasPool).AddGas(tx.Gas()))
    if err != nil {
        return nil, fmt.Errorf("tracing failed: %v", err)
    }
    switch tracer := tracer.(type) {
    case *vm.StructLogger:
        return &ethapi.ExecutionResult{
            Gas:         gas,
            Failed:      failed,
            ReturnValue: fmt.Sprintf("%x", ret),
            StructLogs:  ethapi.FormatLogs(tracer.StructLogs()),
        }, nil
    case *ethapi.JavascriptTracer:
        return tracer.GetResult()
    default:
        panic(fmt.Sprintf("bad tracer type %T", tracer))
    }
}

// computeTxEnv returns the execution environment of a certain transaction.
func (api *PrivateDebugAPI) computeTxEnv(blockHash common.Hash, txIndex int) (core.Message, vm.Context, *state.StateDB, error) {
    // Create the parent state.
    block := api.eth.BlockChain().GetBlockByHash(blockHash)
    if block == nil {
        return nil, vm.Context{}, nil, fmt.Errorf("block %x not found", blockHash)
    }
    parent := api.eth.BlockChain().GetBlock(block.ParentHash(), block.NumberU64()-1)
    if parent == nil {
        return nil, vm.Context{}, nil, fmt.Errorf("block parent %x not found", block.ParentHash())
    }
    statedb, err := api.eth.BlockChain().StateAt(parent.Root())
    if err != nil {
        return nil, vm.Context{}, nil, err
    }
    txs := block.Transactions()

    // Recompute transactions up to the target index.
    signer := types.MakeSigner(api.config, block.Number())
    for idx, tx := range txs {
        // Assemble the transaction call message
        msg, _ := tx.AsMessage(signer)
        context := core.NewEVMContext(msg, block.Header(), api.eth.BlockChain(), nil)
        if idx == txIndex {
            return msg, context, statedb, nil
        }

        vmenv := vm.NewEVM(context, statedb, api.config, vm.Config{})
        gp := new(core.GasPool).AddGas(tx.Gas())
        _, _, _, err := core.ApplyMessage(vmenv, msg, gp)
        if err != nil {
            return nil, vm.Context{}, nil, fmt.Errorf("tx %x failed: %v", tx.Hash(), err)
        }
        statedb.DeleteSuicides()
    }
    return nil, vm.Context{}, nil, fmt.Errorf("tx index %d out of range for block %x", txIndex, blockHash)
}

// Preimage is a debug API function that returns the preimage for a sha3 hash, if known.
func (api *PrivateDebugAPI) Preimage(ctx context.Context, hash common.Hash) (hexutil.Bytes, error) {
    db := core.PreimageTable(api.eth.ChainDb())
    return db.Get(hash.Bytes())
}

// GetBadBLocks returns a list of the last 'bad blocks' that the client has seen on the network
// and returns them as a JSON list of block-hashes
func (api *PrivateDebugAPI) GetBadBlocks(ctx context.Context) ([]core.BadBlockArgs, error) {
    return api.eth.BlockChain().BadBlocks()
}

// StorageRangeResult is the result of a debug_storageRangeAt API call.
type StorageRangeResult struct {
    Storage storageMap   `json:"storage"`
    NextKey *common.Hash `json:"nextKey"` // nil if Storage includes the last key in the trie.
}

type storageMap map[common.Hash]storageEntry

type storageEntry struct {
    Key   *common.Hash `json:"key"`
    Value common.Hash  `json:"value"`
}

// StorageRangeAt returns the storage at the given block height and transaction index.
func (api *PrivateDebugAPI) StorageRangeAt(ctx context.Context, blockHash common.Hash, txIndex int, contractAddress common.Address, keyStart hexutil.Bytes, maxResult int) (StorageRangeResult, error) {
    _, _, statedb, err := api.computeTxEnv(blockHash, txIndex)
    if err != nil {
        return StorageRangeResult{}, err
    }
    st := statedb.StorageTrie(contractAddress)
    if st == nil {
        return StorageRangeResult{}, fmt.Errorf("account %x doesn't exist", contractAddress)
    }
    return storageRangeAt(st, keyStart, maxResult), nil
}

func storageRangeAt(st state.Trie, start []byte, maxResult int) StorageRangeResult {
    it := trie.NewIterator(st.NodeIterator(start))
    result := StorageRangeResult{Storage: storageMap{}}
    for i := 0; i < maxResult && it.Next(); i++ {
        e := storageEntry{Value: common.BytesToHash(it.Value)}
        if preimage := st.GetKey(it.Key); preimage != nil {
            preimage := common.BytesToHash(preimage)
            e.Key = &preimage
        }
        result.Storage[common.BytesToHash(it.Key)] = e
    }
    // Add the 'next key' so clients can continue downloading.
    if it.Next() {
        next := common.BytesToHash(it.Key)
        result.NextKey = &next
    }
    return result
}

// GetModifiedAccountsByumber returns all accounts that have changed between the
// two blocks specified. A change is defined as a difference in nonce, balance,
// code hash, or storage hash.
//
// With one parameter, returns the list of accounts modified in the specified block.
func (api *PrivateDebugAPI) GetModifiedAccountsByNumber(startNum uint64, endNum *uint64) ([]common.Address, error) {
    var startBlock, endBlock *types.Block

    startBlock = api.eth.blockchain.GetBlockByNumber(startNum)
    if startBlock == nil {
        return nil, fmt.Errorf("start block %x not found", startNum)
    }

    if endNum == nil {
        endBlock = startBlock
        startBlock = api.eth.blockchain.GetBlockByHash(startBlock.ParentHash())
        if startBlock == nil {
            return nil, fmt.Errorf("block %x has no parent", endBlock.Number())
        }
    } else {
        endBlock = api.eth.blockchain.GetBlockByNumber(*endNum)
        if endBlock == nil {
            return nil, fmt.Errorf("end block %d not found", *endNum)
        }
    }
    return api.getModifiedAccounts(startBlock, endBlock)
}

// GetModifiedAccountsByHash returns all accounts that have changed between the
// two blocks specified. A change is defined as a difference in nonce, balance,
// code hash, or storage hash.
//
// With one parameter, returns the list of accounts modified in the specified block.
func (api *PrivateDebugAPI) GetModifiedAccountsByHash(startHash common.Hash, endHash *common.Hash) ([]common.Address, error) {
    var startBlock, endBlock *types.Block
    startBlock = api.eth.blockchain.GetBlockByHash(startHash)
    if startBlock == nil {
        return nil, fmt.Errorf("start block %x not found", startHash)
    }

    if endHash == nil {
        endBlock = startBlock
        startBlock = api.eth.blockchain.GetBlockByHash(startBlock.ParentHash())
        if startBlock == nil {
            return nil, fmt.Errorf("block %x has no parent", endBlock.Number())
        }
    } else {
        endBlock = api.eth.blockchain.GetBlockByHash(*endHash)
        if endBlock == nil {
            return nil, fmt.Errorf("end block %x not found", *endHash)
        }
    }
    return api.getModifiedAccounts(startBlock, endBlock)
}

func (api *PrivateDebugAPI) getModifiedAccounts(startBlock, endBlock *types.Block) ([]common.Address, error) {
    if startBlock.Number().Uint64() >= endBlock.Number().Uint64() {
        return nil, fmt.Errorf("start block height (%d) must be less than end block height (%d)", startBlock.Number().Uint64(), endBlock.Number().Uint64())
    }

    oldTrie, err := trie.NewSecure(startBlock.Root(), api.eth.chainDb, 0)
    if err != nil {
        return nil, err
    }
    newTrie, err := trie.NewSecure(endBlock.Root(), api.eth.chainDb, 0)
    if err != nil {
        return nil, err
    }

    diff, _ := trie.NewDifferenceIterator(oldTrie.NodeIterator([]byte{}), newTrie.NodeIterator([]byte{}))
    iter := trie.NewIterator(diff)

    var dirty []common.Address
    for iter.Next() {
        key := newTrie.GetKey(iter.Key)
        if key == nil {
            return nil, fmt.Errorf("no preimage found for hash %x", iter.Key)
        }
        dirty = append(dirty, common.BytesToAddress(key))
    }
    return dirty, nil
}