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 (
    "context"
    "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/ethdb"
    "github.com/dexon-foundation/dexon/event"
    "github.com/dexon-foundation/dexon/log"
    "github.com/dexon-foundation/dexon/rlp"
)

const (
    verifyBlockMaxRetries = 4
)

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

    finalizedBlockFeed event.Feed
    scope              event.SubscriptionScope

    chainLocks      sync.Map
    chainLatestRoot sync.Map
}

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) *DexconApp {
    return &DexconApp{
        txPool:     txPool,
        blockchain: blockchain,
        gov:        gov,
        chainDB:    chainDB,
        config:     config,
    }
}

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) chainLock(chainID uint32) {
    v, ok := d.chainLocks.Load(chainID)
    if !ok {
        v = &sync.RWMutex{}
        d.chainLocks.Store(chainID, v)
    }
    v.(*sync.RWMutex).Lock()
}

func (d *DexconApp) chainUnlock(chainID uint32) {
    v, ok := d.chainLocks.Load(chainID)
    if !ok {
        panic(fmt.Errorf("chain %v is not init yet", chainID))
    }
    v.(*sync.RWMutex).Unlock()
}

func (d *DexconApp) chainRLock(chainID uint32) {
    v, ok := d.chainLocks.Load(chainID)
    if !ok {
        v = &sync.RWMutex{}
        d.chainLocks.Store(chainID, v)
    }
    v.(*sync.RWMutex).RLock()
}

func (d *DexconApp) chainRUnlock(chainID uint32) {
    v, ok := d.chainLocks.Load(chainID)
    if !ok {
        panic(fmt.Errorf("chain %v is not init yet", chainID))
    }
    v.(*sync.RWMutex).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) {
    // softLimit limits the runtime of inner call to preparePayload.
    // hardLimit limits the runtime of outer PreparePayload.
    // If hardLimit is hit, it is possible that no payload is prepared.
    softLimit := 100 * time.Millisecond
    hardLimit := 150 * time.Millisecond
    ctx, cancel := context.WithTimeout(context.Background(), hardLimit)
    defer cancel()
    payloadCh := make(chan []byte, 1)
    errCh := make(chan error, 1)
    doneCh := make(chan struct{}, 1)
    go func() {
        ctx, cancel := context.WithTimeout(context.Background(), softLimit)
        defer cancel()
        payload, err := d.preparePayload(ctx, position)
        if err != nil {
            errCh <- err
        }
        payloadCh <- payload
        doneCh <- struct{}{}
    }()
    select {
    case <-ctx.Done():
    case <-doneCh:
    }
    select {
    case err = <-errCh:
        if err != nil {
            return
        }
    default:
    }
    select {
    case payload = <-payloadCh:
    default:
    }
    return
}

func (d *DexconApp) preparePayload(ctx context.Context, position coreTypes.Position) (
    payload []byte, err error) {
    d.chainRLock(position.ChainID)
    defer d.chainRUnlock(position.ChainID)
    select {
    // This case will hit if previous RLock took too much time.
    case <-ctx.Done():
        return
    default:
    }

    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")
        }
    }

    b, latestState := d.blockchain.GetPending()
    log.Debug("Prepare payload", "chain", position.ChainID, "height", position.Height, "state",
        b.Root().String())

    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(d.blockchain.CurrentBlock().GasLimit())
    blockGasUsed := new(big.Int)
    allTxs := make([]*types.Transaction, 0, 3000)

addressMap:
    for address, txs := range txsMap {
        select {
        case <-ctx.Done():
            break addressMap
        default:
        }
        // 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
        }

        if len(txs) == 0 {
            continue
        }

        firstNonce := txs[0].Nonce()
        startIndex := int(expectNonce - firstNonce)

        for i := startIndex; i < len(txs); i++ {
            tx := txs[i]
            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.GetPendingHeight()
    if lastPendingHeight == 0 && consensusHeight == 0 {
        witnessBlock = d.blockchain.CurrentBlock()
    } else if lastPendingHeight >= consensusHeight {
        witnessBlock = d.blockchain.PendingBlock()
    } else {
        log.Error("last pending height too low", "lastPendingHeight", lastPendingHeight,
            "consensusHeight", consensusHeight)
        return witness, fmt.Errorf("last pending height < consensus height")
    }

    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; i++ {
        if d.blockchain.GetPendingHeight() < block.Witness.Height {
            log.Debug("Pending height < witness height")
            time.Sleep(500 * time.Millisecond)
            continue
        }

        b := d.blockchain.GetPendingBlockByNumber(block.Witness.Height)
        if b == nil {
            b = d.blockchain.GetBlockByNumber(block.Witness.Height)
            if b == nil {
                log.Error("Can not get block by height %v", block.Witness.Height)
                return coreTypes.VerifyInvalidBlock
            }
        }

        if b.Root() != witnessData.Root {
            log.Error("Witness root not correct expect %v but %v", b.Root(), witnessData.Root)
            return coreTypes.VerifyInvalidBlock
        }

        if b.ReceiptHash() != witnessData.ReceiptHash {
            log.Error("Witness receipt hash not correct expect %v but %v", b.ReceiptHash(), witnessData.ReceiptHash)
            return coreTypes.VerifyInvalidBlock
        }

        _, err = d.blockchain.StateAt(witnessData.Root)
        if err != nil {
            log.Error("Get state by root %v error: %v", witnessData.Root, err)
            return coreTypes.VerifyInvalidBlock
        }

        break
    }

    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
        }
    }

    // Get latest pending state.
    b, latestState := d.blockchain.GetPending()
    log.Debug("Verify block", "chain", block.Position.ChainID, "height", block.Position.Height, "state",
        b.Root().String())

    var transactions types.Transactions
    if len(block.Payload) == 0 {
        return coreTypes.VerifyOK
    }
    err = rlp.DecodeBytes(block.Payload, &transactions)
    if err != nil {
        log.Error("Payload rlp decode", "error", err)
        return coreTypes.VerifyInvalidBlock
    }

    _, err = types.GlobalSigCache.Add(types.NewEIP155Signer(d.blockchain.Config().ChainID), transactions)
    if err != nil {
        log.Error("Failed to calculate sender", "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(d.blockchain.CurrentBlock().GasLimit())
    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, txs := d.blockchain.GetConfirmedBlockByHash(chainID, blockHash)
    if block == nil {
        panic("Can not get confirmed block")
    }

    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,
    }, txs, nil, nil)

    h := d.blockchain.CurrentBlock().NumberU64() + 1
    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)

    d.blockchain.RemoveConfirmedBlock(chainID, blockHash)

    // New blocks are finalized, notify other components.
    newHeight := d.blockchain.CurrentBlock().NumberU64()
    for h <= newHeight {
        b := d.blockchain.GetBlockByNumber(h)
        go d.finalizedBlockFeed.Send(core.NewFinalizedBlockEvent{b})
        log.Debug("Send new finalized block event", "number", h)
        h++
    }
}

// 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)

    if err := d.blockchain.AddConfirmedBlock(&block); err != nil {
        panic(err)
    }
}

func (d *DexconApp) SubscribeNewFinalizedBlockEvent(
    ch chan<- core.NewFinalizedBlockEvent) event.Subscription {
    return d.scope.Track(d.finalizedBlockFeed.Subscribe(ch))
}

func (d *DexconApp) Stop() {
    d.scope.Close()
}