path: root/core/block_processor.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 core

import (
    "fmt"
    "math/big"
    "sync"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core/state"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/crypto"
    "github.com/ethereum/go-ethereum/event"
    "github.com/ethereum/go-ethereum/logger"
    "github.com/ethereum/go-ethereum/logger/glog"
    "github.com/ethereum/go-ethereum/params"
    "github.com/ethereum/go-ethereum/pow"
    "gopkg.in/fatih/set.v0"
)

const (
    // must be bumped when consensus algorithm is changed, this forces the upgradedb
    // command to be run (forces the blocks to be imported again using the new algorithm)
    BlockChainVersion = 3
)

type BlockProcessor struct {
    chainDb common.Database
    // Mutex for locking the block processor. Blocks can only be handled one at a time
    mutex sync.Mutex
    // Canonical block chain
    bc *ChainManager
    // non-persistent key/value memory storage
    mem map[string]*big.Int
    // Proof of work used for validating
    Pow pow.PoW

    events event.Subscription

    eventMux *event.TypeMux
}

// TODO: type GasPool big.Int
//
// GasPool is implemented by state.StateObject. This is a historical
// coincidence. Gas tracking should move out of StateObject.

// GasPool tracks the amount of gas available during
// execution of the transactions in a block.
type GasPool interface {
    AddGas(gas, price *big.Int)
    SubGas(gas, price *big.Int) error
}

func NewBlockProcessor(db common.Database, pow pow.PoW, chainManager *ChainManager, eventMux *event.TypeMux) *BlockProcessor {
    sm := &BlockProcessor{
        chainDb:  db,
        mem:      make(map[string]*big.Int),
        Pow:      pow,
        bc:       chainManager,
        eventMux: eventMux,
    }
    return sm
}

func (sm *BlockProcessor) TransitionState(statedb *state.StateDB, parent, block *types.Block, transientProcess bool) (receipts types.Receipts, err error) {
    gp := statedb.GetOrNewStateObject(block.Coinbase())
    gp.SetGasLimit(block.GasLimit())

    // Process the transactions on to parent state
    receipts, err = sm.ApplyTransactions(gp, statedb, block, block.Transactions(), transientProcess)
    if err != nil {
        return nil, err
    }

    return receipts, nil
}

func (self *BlockProcessor) ApplyTransaction(gp GasPool, statedb *state.StateDB, header *types.Header, tx *types.Transaction, usedGas *big.Int, transientProcess bool) (*types.Receipt, *big.Int, error) {
    _, gas, err := ApplyMessage(NewEnv(statedb, self.bc, tx, header), tx, gp)
    if err != nil {
        return nil, nil, err
    }

    // Update the state with pending changes
    statedb.SyncIntermediate()

    usedGas.Add(usedGas, gas)
    receipt := types.NewReceipt(statedb.Root().Bytes(), usedGas)
    receipt.TxHash = tx.Hash()
    receipt.GasUsed = new(big.Int).Set(gas)
    if MessageCreatesContract(tx) {
        from, _ := tx.From()
        receipt.ContractAddress = crypto.CreateAddress(from, tx.Nonce())
    }

    logs := statedb.GetLogs(tx.Hash())
    receipt.SetLogs(logs)
    receipt.Bloom = types.CreateBloom(types.Receipts{receipt})

    glog.V(logger.Debug).Infoln(receipt)

    // Notify all subscribers
    if !transientProcess {
        go self.eventMux.Post(TxPostEvent{tx})
        go self.eventMux.Post(logs)
    }

    return receipt, gas, err
}
func (self *BlockProcessor) ChainManager() *ChainManager {
    return self.bc
}

func (self *BlockProcessor) ApplyTransactions(gp GasPool, statedb *state.StateDB, block *types.Block, txs types.Transactions, transientProcess bool) (types.Receipts, error) {
    var (
        receipts      types.Receipts
        totalUsedGas  = big.NewInt(0)
        err           error
        cumulativeSum = new(big.Int)
        header        = block.Header()
    )

    for i, tx := range txs {
        statedb.StartRecord(tx.Hash(), block.Hash(), i)

        receipt, txGas, err := self.ApplyTransaction(gp, statedb, header, tx, totalUsedGas, transientProcess)
        if err != nil {
            return nil, err
        }

        if err != nil {
            glog.V(logger.Core).Infoln("TX err:", err)
        }
        receipts = append(receipts, receipt)

        cumulativeSum.Add(cumulativeSum, new(big.Int).Mul(txGas, tx.GasPrice()))
    }

    if block.GasUsed().Cmp(totalUsedGas) != 0 {
        return nil, ValidationError(fmt.Sprintf("gas used error (%v / %v)", block.GasUsed(), totalUsedGas))
    }

    if transientProcess {
        go self.eventMux.Post(PendingBlockEvent{block, statedb.Logs()})
    }

    return receipts, err
}

func (sm *BlockProcessor) RetryProcess(block *types.Block) (logs state.Logs, err error) {
    // Processing a blocks may never happen simultaneously
    sm.mutex.Lock()
    defer sm.mutex.Unlock()

    if !sm.bc.HasBlock(block.ParentHash()) {
        return nil, ParentError(block.ParentHash())
    }
    parent := sm.bc.GetBlock(block.ParentHash())

    // FIXME Change to full header validation. See #1225
    errch := make(chan bool)
    go func() { errch <- sm.Pow.Verify(block) }()

    logs, _, err = sm.processWithParent(block, parent)
    if !<-errch {
        return nil, ValidationError("Block's nonce is invalid (= %x)", block.Nonce)
    }

    return logs, err
}

// Process block will attempt to process the given block's transactions and applies them
// on top of the block's parent state (given it exists) and will return wether it was
// successful or not.
func (sm *BlockProcessor) Process(block *types.Block) (logs state.Logs, receipts types.Receipts, err error) {
    // Processing a blocks may never happen simultaneously
    sm.mutex.Lock()
    defer sm.mutex.Unlock()

    if sm.bc.HasBlock(block.Hash()) {
        return nil, nil, &KnownBlockError{block.Number(), block.Hash()}
    }

    if !sm.bc.HasBlock(block.ParentHash()) {
        return nil, nil, ParentError(block.ParentHash())
    }
    parent := sm.bc.GetBlock(block.ParentHash())
    return sm.processWithParent(block, parent)
}

func (sm *BlockProcessor) processWithParent(block, parent *types.Block) (logs state.Logs, receipts types.Receipts, err error) {
    // Create a new state based on the parent's root (e.g., create copy)
    state := state.New(parent.Root(), sm.chainDb)
    header := block.Header()
    uncles := block.Uncles()
    txs := block.Transactions()

    // Block validation
    if err = ValidateHeader(sm.Pow, header, parent, false, false); err != nil {
        return
    }

    // There can be at most two uncles
    if len(uncles) > 2 {
        return nil, nil, ValidationError("Block can only contain maximum 2 uncles (contained %v)", len(uncles))
    }

    receipts, err = sm.TransitionState(state, parent, block, false)
    if err != nil {
        return
    }

    // Validate the received block's bloom with the one derived from the generated receipts.
    // For valid blocks this should always validate to true.
    rbloom := types.CreateBloom(receipts)
    if rbloom != header.Bloom {
        err = fmt.Errorf("unable to replicate block's bloom=%x", rbloom)
        return
    }

    // The transactions Trie's root (R = (Tr [[i, RLP(T1)], [i, RLP(T2)], ... [n, RLP(Tn)]]))
    // can be used by light clients to make sure they've received the correct Txs
    txSha := types.DeriveSha(txs)
    if txSha != header.TxHash {
        err = fmt.Errorf("invalid transaction root hash. received=%x calculated=%x", header.TxHash, txSha)
        return
    }

    // Tre receipt Trie's root (R = (Tr [[H1, R1], ... [Hn, R1]]))
    receiptSha := types.DeriveSha(receipts)
    if receiptSha != header.ReceiptHash {
        err = fmt.Errorf("invalid receipt root hash. received=%x calculated=%x", header.ReceiptHash, receiptSha)
        return
    }

    // Verify UncleHash before running other uncle validations
    unclesSha := types.CalcUncleHash(uncles)
    if unclesSha != header.UncleHash {
        err = fmt.Errorf("invalid uncles root hash. received=%x calculated=%x", header.UncleHash, unclesSha)
        return
    }

    // Verify uncles
    if err = sm.VerifyUncles(state, block, parent); err != nil {
        return
    }
    // Accumulate static rewards; block reward, uncle's and uncle inclusion.
    AccumulateRewards(state, header, uncles)

    // Commit state objects/accounts to a temporary trie (does not save)
    // used to calculate the state root.
    state.SyncObjects()
    if header.Root != state.Root() {
        err = fmt.Errorf("invalid merkle root. received=%x got=%x", header.Root, state.Root())
        return
    }

    // Sync the current block's state to the database
    state.Sync()

    return state.Logs(), receipts, nil
}

var (
    big8  = big.NewInt(8)
    big32 = big.NewInt(32)
)

// AccumulateRewards credits the coinbase of the given block with the
// mining reward. The total reward consists of the static block reward
// and rewards for included uncles. The coinbase of each uncle block is
// also rewarded.
func AccumulateRewards(statedb *state.StateDB, header *types.Header, uncles []*types.Header) {
    reward := new(big.Int).Set(BlockReward)
    r := new(big.Int)
    for _, uncle := range uncles {
        r.Add(uncle.Number, big8)
        r.Sub(r, header.Number)
        r.Mul(r, BlockReward)
        r.Div(r, big8)
        statedb.AddBalance(uncle.Coinbase, r)

        r.Div(BlockReward, big32)
        reward.Add(reward, r)
    }
    statedb.AddBalance(header.Coinbase, reward)
}

func (sm *BlockProcessor) VerifyUncles(statedb *state.StateDB, block, parent *types.Block) error {
    uncles := set.New()
    ancestors := make(map[common.Hash]*types.Block)
    for _, ancestor := range sm.bc.GetBlocksFromHash(block.ParentHash(), 7) {
        ancestors[ancestor.Hash()] = ancestor
        // Include ancestors uncles in the uncle set. Uncles must be unique.
        for _, uncle := range ancestor.Uncles() {
            uncles.Add(uncle.Hash())
        }
    }
    ancestors[block.Hash()] = block
    uncles.Add(block.Hash())

    for i, uncle := range block.Uncles() {
        hash := uncle.Hash()
        if uncles.Has(hash) {
            // Error not unique
            return UncleError("uncle[%d](%x) not unique", i, hash[:4])
        }
        uncles.Add(hash)

        if ancestors[hash] != nil {
            branch := fmt.Sprintf("  O - %x\n  |\n", block.Hash())
            for h := range ancestors {
                branch += fmt.Sprintf("  O - %x\n  |\n", h)
            }
            glog.Infoln(branch)
            return UncleError("uncle[%d](%x) is ancestor", i, hash[:4])
        }

        if ancestors[uncle.ParentHash] == nil || uncle.ParentHash == parent.Hash() {
            return UncleError("uncle[%d](%x)'s parent is not ancestor (%x)", i, hash[:4], uncle.ParentHash[0:4])
        }

        if err := ValidateHeader(sm.Pow, uncle, ancestors[uncle.ParentHash], true, true); err != nil {
            return ValidationError(fmt.Sprintf("uncle[%d](%x) header invalid: %v", i, hash[:4], err))
        }
    }

    return nil
}

// GetBlockReceipts returns the receipts beloniging to the block hash
func (sm *BlockProcessor) GetBlockReceipts(bhash common.Hash) types.Receipts {
    if block := sm.ChainManager().GetBlock(bhash); block != nil {
        return GetBlockReceipts(sm.chainDb, block.Hash())
    }

    return nil
}

// GetLogs returns the logs of the given block. This method is using a two step approach
// where it tries to get it from the (updated) method which gets them from the receipts or
// the depricated way by re-processing the block.
func (sm *BlockProcessor) GetLogs(block *types.Block) (logs state.Logs, err error) {
    receipts := GetBlockReceipts(sm.chainDb, block.Hash())
    // coalesce logs
    for _, receipt := range receipts {
        logs = append(logs, receipt.Logs()...)
    }
    return logs, nil
}

// See YP section 4.3.4. "Block Header Validity"
// Validates a block. Returns an error if the block is invalid.
func ValidateHeader(pow pow.PoW, block *types.Header, parent *types.Block, checkPow, uncle bool) error {
    if big.NewInt(int64(len(block.Extra))).Cmp(params.MaximumExtraDataSize) == 1 {
        return fmt.Errorf("Block extra data too long (%d)", len(block.Extra))
    }

    if uncle {
        if block.Time.Cmp(common.MaxBig) == 1 {
            return BlockTSTooBigErr
        }
    } else {
        if block.Time.Cmp(big.NewInt(time.Now().Unix())) == 1 {
            return BlockFutureErr
        }
    }
    if block.Time.Cmp(parent.Time()) != 1 {
        return BlockEqualTSErr
    }

    expd := CalcDifficulty(block.Time.Uint64(), parent.Time().Uint64(), parent.Number(), parent.Difficulty())
    if expd.Cmp(block.Difficulty) != 0 {
        return fmt.Errorf("Difficulty check failed for block %v, %v", block.Difficulty, expd)
    }

    var a, b *big.Int
    a = parent.GasLimit()
    a = a.Sub(a, block.GasLimit)
    a.Abs(a)
    b = parent.GasLimit()
    b = b.Div(b, params.GasLimitBoundDivisor)
    if !(a.Cmp(b) < 0) || (block.GasLimit.Cmp(params.MinGasLimit) == -1) {
        return fmt.Errorf("GasLimit check failed for block %v (%v > %v)", block.GasLimit, a, b)
    }

    num := parent.Number()
    num.Sub(block.Number, num)
    if num.Cmp(big.NewInt(1)) != 0 {
        return BlockNumberErr
    }

    if checkPow {
        // Verify the nonce of the block. Return an error if it's not valid
        if !pow.Verify(types.NewBlockWithHeader(block)) {
            return ValidationError("Block's nonce is invalid (= %x)", block.Nonce)
        }
    }

    return nil
}