path: root/dex/app.go

// Copyright 2018 The dexon-consensus Authors
// This file is part of the dexon-consensus library.
//
// The dexon-consensus 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 dexon-consensus 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 dexon-consensus library. If not, see
// <http://www.gnu.org/licenses/>.

package dex

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

    coreCommon "github.com/dexon-foundation/dexon-consensus/common"
    coreTypes "github.com/dexon-foundation/dexon-consensus/core/types"

    "github.com/dexon-foundation/dexon/common"
    "github.com/dexon-foundation/dexon/core"
    "github.com/dexon-foundation/dexon/core/types"
    "github.com/dexon-foundation/dexon/core/vm"
    "github.com/dexon-foundation/dexon/ethdb"
    "github.com/dexon-foundation/dexon/log"
    "github.com/dexon-foundation/dexon/rlp"
)

const (
    verifyBlockMaxRetries = 4
)

// DexconApp implementes the DEXON consensus core application interface.
type DexconApp struct {
    txPool     *core.TxPool
    blockchain *core.BlockChain
    gov        *DexconGovernance
    chainDB    ethdb.Database
    config     *Config
    vmConfig   vm.Config

    chainLocksInitMu sync.Mutex
    chainLocks       map[uint32]*sync.RWMutex

    notifyChan      sync.Map
    chainLatestRoot sync.Map
}

type notify struct {
    results []chan uint64
}

type witnessData struct {
    Root        common.Hash
    TxHash      common.Hash
    ReceiptHash common.Hash
}

func NewDexconApp(txPool *core.TxPool, blockchain *core.BlockChain, gov *DexconGovernance,
    chainDB ethdb.Database, config *Config, vmConfig vm.Config) *DexconApp {
    return &DexconApp{
        txPool:     txPool,
        blockchain: blockchain,
        gov:        gov,
        chainDB:    chainDB,
        config:     config,
        vmConfig:   vmConfig,
        chainLocks: make(map[uint32]*sync.RWMutex),
    }
}

func (d *DexconApp) addNotify(height uint64) <-chan uint64 {
    result := make(chan uint64)
    v, ok := d.notifyChan.Load(height)
    if ok {
        n := v.(*notify)
        n.results = append(n.results, result)
    } else {
        n := &notify{results: []chan uint64{result}}
        d.notifyChan.Store(height, n)
    }
    return result
}

func (d *DexconApp) notify(height uint64) {
    d.notifyChan.Range(func(key, value interface{}) bool {
        h := key.(uint64)
        n := value.(*notify)

        if height >= h {
            for _, ch := range n.results {
                ch <- height
            }
            d.notifyChan.Delete(key)
        }
        return true
    })
}

func (d *DexconApp) addrBelongsToChain(address common.Address, chainSize, chainID *big.Int) bool {
    return new(big.Int).Mod(address.Big(), chainSize).Cmp(chainID) == 0
}

func (d *DexconApp) chainLockInit(chainID uint32) {
    d.chainLocksInitMu.Lock()
    defer d.chainLocksInitMu.Unlock()

    _, exist := d.chainLocks[chainID]
    if !exist {
        d.chainLocks[chainID] = &sync.RWMutex{}
    }
}

func (d *DexconApp) chainLock(chainID uint32) {
    d.chainLockInit(chainID)
    d.chainLocks[chainID].Lock()
}

func (d *DexconApp) chainUnlock(chainID uint32) {
    d.chainLocks[chainID].Unlock()
}

func (d *DexconApp) chainRLock(chainID uint32) {
    d.chainLockInit(chainID)
    d.chainLocks[chainID].RLock()
}

func (d *DexconApp) chainRUnlock(chainID uint32) {
    d.chainLocks[chainID].RUnlock()
}

// validateNonce check if nonce is in order and return first nonce of every address.
func (d *DexconApp) validateNonce(txs types.Transactions) (map[common.Address]uint64, error) {
    addressFirstNonce := map[common.Address]uint64{}
    addressNonce := map[common.Address]uint64{}

    for _, tx := range txs {
        msg, err := tx.AsMessage(types.MakeSigner(d.blockchain.Config(), new(big.Int)))
        if err != nil {
            return nil, err
        }

        if _, exist := addressFirstNonce[msg.From()]; exist {
            if addressNonce[msg.From()]+1 != msg.Nonce() {
                return nil, fmt.Errorf("address nonce check error: expect %v actual %v",
                    addressNonce[msg.From()]+1, msg.Nonce())
            }
            addressNonce[msg.From()] = msg.Nonce()
        } else {
            addressNonce[msg.From()] = msg.Nonce()
            addressFirstNonce[msg.From()] = msg.Nonce()
        }
    }
    return addressFirstNonce, nil
}

// PreparePayload is called when consensus core is preparing payload for block.
func (d *DexconApp) PreparePayload(position coreTypes.Position) (payload []byte, err error) {
    d.chainRLock(position.ChainID)
    defer d.chainRUnlock(position.ChainID)

    if position.Height != 0 {
        // Check if chain block height is strictly increamental.
        chainLastHeight := d.blockchain.GetChainLastConfirmedHeight(position.ChainID)
        if chainLastHeight != position.Height-1 {
            log.Error("Check confirmed block height fail",
                "chain", position.ChainID, "height", position.Height-1, "cache height", chainLastHeight)
            return nil, fmt.Errorf("check confirmed block height fail")
        }
    }

    var root *common.Hash
    value, ok := d.chainLatestRoot.Load(position.ChainID)
    if ok {
        root = value.(*common.Hash)
    } else {
        currentRoot := d.blockchain.CurrentBlock().Root()
        root = &currentRoot
    }

    // Set state to the chain latest height.
    latestState, err := d.blockchain.StateAt(*root)
    if err != nil {
        log.Error("Get pending state", "error", err)
        return nil, fmt.Errorf("get pending state error: %v", err)
    }

    txsMap, err := d.txPool.Pending()
    if err != nil {
        return
    }

    chainID := new(big.Int).SetUint64(uint64(position.ChainID))
    chainNums := new(big.Int).SetUint64(uint64(d.gov.GetNumChains(position.Round)))
    blockGasLimit := new(big.Int).SetUint64(core.CalcGasLimit(d.blockchain.CurrentBlock(),
        d.config.GasFloor, d.config.GasCeil))
    blockGasUsed := new(big.Int)
    var allTxs types.Transactions

addressMap:
    for address, txs := range txsMap {
        // TX hash need to be slot to the given chain in order to be included in the block.
        if !d.addrBelongsToChain(address, chainNums, chainID) {
            continue
        }

        balance := latestState.GetBalance(address)
        cost, exist := d.blockchain.GetCostInConfirmedBlocks(position.ChainID, address)
        if exist {
            balance = new(big.Int).Sub(balance, cost)
        }

        var expectNonce uint64
        lastConfirmedNonce, exist := d.blockchain.GetLastNonceInConfirmedBlocks(position.ChainID, address)
        if !exist {
            expectNonce = latestState.GetNonce(address)
        } else {
            expectNonce = lastConfirmedNonce + 1
        }

        for _, tx := range txs {
            if expectNonce == tx.Nonce() {
                expectNonce++
            } else if expectNonce < tx.Nonce() {
                break
            } else if expectNonce > tx.Nonce() {
                log.Debug("Skipping tx with smaller nonce then expected", "expected", expectNonce, "nonce", tx.Nonce())
                continue
            }

            intrGas, err := core.IntrinsicGas(tx.Data(), tx.To() == nil, true)
            if err != nil {
                log.Error("Failed to calculate intrinsic gas", "error", err)
                return nil, fmt.Errorf("calculate intrinsic gas error: %v", err)
            }
            if tx.Gas() < intrGas {
                log.Error("Intrinsic gas too low", "txHash", tx.Hash().String())
                break
            }

            balance = new(big.Int).Sub(balance, tx.Cost())
            if balance.Cmp(big.NewInt(0)) < 0 {
                log.Warn("Insufficient funds for gas * price + value", "txHash", tx.Hash().String())
                break
            }

            blockGasUsed = new(big.Int).Add(blockGasUsed, big.NewInt(int64(tx.Gas())))
            if blockGasUsed.Cmp(blockGasLimit) > 0 {
                break addressMap
            }

            allTxs = append(allTxs, tx)
        }
    }

    return rlp.EncodeToBytes(&allTxs)
}

// PrepareWitness will return the witness data no lower than consensusHeight.
func (d *DexconApp) PrepareWitness(consensusHeight uint64) (witness coreTypes.Witness, err error) {
    var witnessBlock *types.Block
    lastPendingHeight := d.blockchain.GetLastPendingHeight()
    if lastPendingHeight == 0 && consensusHeight == 0 {
        witnessBlock = d.blockchain.CurrentBlock()
    } else if lastPendingHeight >= consensusHeight {
        witnessBlock = d.blockchain.GetLastPendingBlock()
    } else if h := <-d.addNotify(consensusHeight); h >= consensusHeight {
        witnessBlock = d.blockchain.GetLastPendingBlock()
    } else {
        log.Error("need pending block")
        return witness, fmt.Errorf("need pending block")
    }

    witnessData, err := rlp.EncodeToBytes(&witnessData{
        Root:        witnessBlock.Root(),
        TxHash:      witnessBlock.TxHash(),
        ReceiptHash: witnessBlock.ReceiptHash(),
    })
    if err != nil {
        return
    }

    return coreTypes.Witness{
        Height: witnessBlock.NumberU64(),
        Data:   witnessData,
    }, nil
}

// VerifyBlock verifies if the payloads are valid.
func (d *DexconApp) VerifyBlock(block *coreTypes.Block) coreTypes.BlockVerifyStatus {
    var witnessData witnessData
    err := rlp.DecodeBytes(block.Witness.Data, &witnessData)
    if err != nil {
        log.Error("failed to RLP decode witness data", "error", err)
        return coreTypes.VerifyInvalidBlock
    }

    // Wait until the witnessed root is seen on our local chain.
    for i := 0; i < verifyBlockMaxRetries && err != nil; i++ {
        _, err = d.blockchain.StateAt(witnessData.Root)
        if err != nil {
            log.Debug("Witness root not found, retry in 500ms", "error", err)
            time.Sleep(500 * time.Millisecond)
        }
    }

    if err != nil {
        log.Error("Expected witness root not in stateDB", "err", err)
        return coreTypes.VerifyRetryLater
    }

    d.chainRLock(block.Position.ChainID)
    defer d.chainRUnlock(block.Position.ChainID)

    if block.Position.Height != 0 {
        // Check if target block is the next height to be verified, we can only
        // verify the next block in a given chain.
        chainLastHeight := d.blockchain.GetChainLastConfirmedHeight(block.Position.ChainID)
        if chainLastHeight != block.Position.Height-1 {
            log.Error("Check confirmed block height fail", "chain", block.Position.ChainID,
                "height", block.Position.Height-1, "cache height", chainLastHeight)
            return coreTypes.VerifyRetryLater
        }
    }

    // Find the latest state for the given block height.
    var root *common.Hash
    value, ok := d.chainLatestRoot.Load(block.Position.ChainID)
    if ok {
        root = value.(*common.Hash)
    } else {
        currentRoot := d.blockchain.CurrentBlock().Root()
        root = &currentRoot
    }

    latestState, err := d.blockchain.StateAt(*root)
    if err != nil {
        log.Error("Failed to get pending state", "error", err)
        return coreTypes.VerifyInvalidBlock
    }

    var transactions types.Transactions
    err = rlp.DecodeBytes(block.Payload, &transactions)
    if err != nil {
        log.Error("Payload rlp decode", "error", err)
        return coreTypes.VerifyInvalidBlock
    }

    addressNonce, err := d.validateNonce(transactions)
    if err != nil {
        log.Error("Validate nonce failed", "error", err)
        return coreTypes.VerifyInvalidBlock
    }

    // Check if nonce is strictly increasing for every address.
    chainID := big.NewInt(int64(block.Position.ChainID))
    chainNums := big.NewInt(int64(d.gov.GetNumChains(block.Position.Round)))

    for address, firstNonce := range addressNonce {
        if !d.addrBelongsToChain(address, chainNums, chainID) {
            log.Error("Address does not belong to given chain ID", "address", address, "chainD", chainID)
            return coreTypes.VerifyInvalidBlock
        }

        var expectNonce uint64
        lastConfirmedNonce, exist := d.blockchain.GetLastNonceInConfirmedBlocks(block.Position.ChainID, address)
        if exist {
            expectNonce = lastConfirmedNonce + 1
        } else {
            expectNonce = latestState.GetNonce(address)
        }

        if expectNonce != firstNonce {
            log.Error("Nonce check error", "expect", expectNonce, "firstNonce", firstNonce)
            return coreTypes.VerifyInvalidBlock
        }
    }

    // Calculate balance in last state (including pending state).
    addressesBalance := map[common.Address]*big.Int{}
    for address := range addressNonce {
        cost, exist := d.blockchain.GetCostInConfirmedBlocks(block.Position.ChainID, address)
        if exist {
            addressesBalance[address] = new(big.Int).Sub(latestState.GetBalance(address), cost)
        } else {
            addressesBalance[address] = latestState.GetBalance(address)
        }
    }

    // Validate if balance is enough for TXs in this block.
    blockGasLimit := new(big.Int).SetUint64(core.CalcGasLimit(
        d.blockchain.CurrentBlock(), d.config.GasFloor, d.config.GasCeil))
    blockGasUsed := new(big.Int)

    for _, tx := range transactions {
        msg, err := tx.AsMessage(types.MakeSigner(d.blockchain.Config(), new(big.Int)))
        if err != nil {
            log.Error("Failed to convert tx to message", "error", err)
            return coreTypes.VerifyInvalidBlock
        }
        balance, _ := addressesBalance[msg.From()]
        intrGas, err := core.IntrinsicGas(msg.Data(), msg.To() == nil, true)
        if err != nil {
            log.Error("Failed to calculate intrinsic gas", "err", err)
            return coreTypes.VerifyInvalidBlock
        }
        if tx.Gas() < intrGas {
            log.Error("Intrinsic gas too low", "txHash", tx.Hash().String(), "intrinsic", intrGas, "gas", tx.Gas())
            return coreTypes.VerifyInvalidBlock
        }

        balance = new(big.Int).Sub(balance, tx.Cost())
        if balance.Cmp(big.NewInt(0)) < 0 {
            log.Error("Insufficient funds for gas * price + value", "txHash", tx.Hash().String())
            return coreTypes.VerifyInvalidBlock
        }

        blockGasUsed = new(big.Int).Add(blockGasUsed, new(big.Int).SetUint64(tx.Gas()))
        if blockGasUsed.Cmp(blockGasLimit) > 0 {
            log.Error("Reach block gas limit", "gasUsed", blockGasUsed)
            return coreTypes.VerifyInvalidBlock
        }
        addressesBalance[msg.From()] = balance
    }

    return coreTypes.VerifyOK
}

// BlockDelivered is called when a block is add to the compaction chain.
func (d *DexconApp) BlockDelivered(
    blockHash coreCommon.Hash,
    blockPosition coreTypes.Position,
    result coreTypes.FinalizationResult) {

    chainID := blockPosition.ChainID
    d.chainLock(chainID)
    defer d.chainUnlock(chainID)

    block := d.blockchain.GetConfirmedBlockByHash(chainID, blockHash)
    if block == nil {
        panic("Can not get confirmed block")
    }

    var transactions types.Transactions
    err := rlp.DecodeBytes(block.Payload, &transactions)
    if err != nil {
        log.Error("Payload rlp decode failed", "error", err)
        panic(err)
    }

    block.Payload = nil
    dexconMeta, err := rlp.EncodeToBytes(block)
    if err != nil {
        panic(err)
    }

    newBlock := types.NewBlock(&types.Header{
        Number:     new(big.Int).SetUint64(result.Height),
        Time:       big.NewInt(result.Timestamp.UnixNano() / 1000000),
        Coinbase:   common.BytesToAddress(block.ProposerID.Bytes()),
        GasLimit:   d.gov.DexconConfiguration(block.Position.Round).BlockGasLimit,
        Difficulty: big.NewInt(1),
        Round:      block.Position.Round,
        DexconMeta: dexconMeta,
        Randomness: result.Randomness,
    }, transactions, nil, nil)

    root, err := d.blockchain.ProcessPendingBlock(newBlock, &block.Witness)
    if err != nil {
        log.Error("Failed to process pending block", "error", err)
        panic(err)
    }
    d.chainLatestRoot.Store(block.Position.ChainID, root)

    log.Info("Insert pending block success", "height", result.Height)
    d.blockchain.RemoveConfirmedBlock(chainID, blockHash)
    d.notify(result.Height)
}

// BlockConfirmed is called when a block is confirmed and added to lattice.
func (d *DexconApp) BlockConfirmed(block coreTypes.Block) {
    d.chainLock(block.Position.ChainID)
    defer d.chainUnlock(block.Position.ChainID)

    d.blockchain.AddConfirmedBlock(&block)
}