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 (
    "bytes"
    "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"
)

// 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

    appMu sync.RWMutex

    confirmedBlocks map[coreCommon.Hash]*blockInfo
    addressNonce    map[common.Address]uint64
    addressCost     map[common.Address]*big.Int
    addressCounter  map[common.Address]uint64
    undeliveredNum  uint64
    deliveredHeight uint64
}

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,
        confirmedBlocks: map[coreCommon.Hash]*blockInfo{},
        addressNonce:    map[common.Address]uint64{},
        addressCost:     map[common.Address]*big.Int{},
        addressCounter:  map[common.Address]uint64{},
        deliveredHeight: blockchain.CurrentBlock().NumberU64(),
    }
}

// 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
}

// validateGasPrice checks if no gas price is lower than minGasPrice defined in
// governance contract.
func (d *DexconApp) validateGasPrice(txs types.Transactions, round uint64) bool {
    minGasPrice := d.gov.MinGasPrice(round)
    for _, tx := range txs {
        if minGasPrice.Cmp(tx.GasPrice()) > 0 {
            return false
        }
    }
    return true
}

// 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.appMu.RLock()
    defer d.appMu.RUnlock()
    select {
    // This case will hit if previous RLock took too much time.
    case <-ctx.Done():
        return
    default:
    }

    // deliver height = position height + 1
    if d.deliveredHeight+d.undeliveredNum != position.Height {
        return nil, fmt.Errorf("expected height %d but get %d", d.deliveredHeight+d.undeliveredNum, position.Height)
    }

    deliveredBlock := d.blockchain.GetBlockByNumber(d.deliveredHeight)
    state, err := d.blockchain.StateAt(deliveredBlock.Root())
    if err != nil {
        return nil, fmt.Errorf("get state by root %v error: %v", deliveredBlock.Root(), err)
    }

    log.Debug("Prepare payload", "height", position.Height)

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

    blockGasLimit := new(big.Int).SetUint64(d.gov.DexconConfiguration(position.Round).BlockGasLimit)
    blockGasUsed := new(big.Int)
    allTxs := make([]*types.Transaction, 0, 10000)

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

        balance := state.GetBalance(address)
        cost, exist := d.addressCost[address]
        if exist {
            balance = new(big.Int).Sub(balance, cost)
        }

        var expectNonce uint64
        lastConfirmedNonce, exist := d.addressNonce[address]
        if !exist {
            expectNonce = state.GetNonce(address)
        } else {
            expectNonce = lastConfirmedNonce + 1
        }

        if len(txs) == 0 {
            continue
        }

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

        // Warning: the pending tx will also affect by syncing, so startIndex maybe negative
        for i := startIndex; i >= 0 && 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
    if d.blockchain.CurrentBlock().NumberU64() >= consensusHeight {
        witnessBlock = d.blockchain.CurrentBlock()
    } else {
        log.Error("Current height too low", "lastPendingHeight", d.blockchain.CurrentBlock().NumberU64(),
            "consensusHeight", consensusHeight)
        return witness, fmt.Errorf("current height < consensus height")
    }

    witnessData, err := rlp.EncodeToBytes(witnessBlock.Hash())
    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 witnessBlockHash common.Hash
    err := rlp.DecodeBytes(block.Witness.Data, &witnessBlockHash)
    if err != nil {
        log.Error("Failed to RLP decode witness data", "error", err)
        return coreTypes.VerifyInvalidBlock
    }

    // Validate witness height.
    if d.blockchain.CurrentBlock().NumberU64() < block.Witness.Height {
        log.Debug("Current height < witness height")
        return coreTypes.VerifyRetryLater
    }

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

    if b.Hash() != witnessBlockHash {
        log.Error("Witness block hash not match",
            "expect", b.Hash().String(), "got", witnessBlockHash.String())
        return coreTypes.VerifyInvalidBlock
    }

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

    d.appMu.RLock()
    defer d.appMu.RUnlock()

    // deliver height = position height + 1
    if d.deliveredHeight+d.undeliveredNum != block.Position.Height {
        return coreTypes.VerifyRetryLater
    }

    var transactions types.Transactions
    if len(block.Payload) == 0 {
        return coreTypes.VerifyOK
    }

    deliveredBlock := d.blockchain.GetBlockByNumber(d.deliveredHeight)
    state, err := d.blockchain.StateAt(deliveredBlock.Root())
    if err != nil {
        return coreTypes.VerifyInvalidBlock
    }

    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
    }
    if !d.validateGasPrice(transactions, block.Position.Round) {
        log.Error("Validate gas price failed")
        return coreTypes.VerifyInvalidBlock
    }

    for address, firstNonce := range addressNonce {
        var expectNonce uint64
        nonce, exist := d.addressNonce[address]
        if exist {
            expectNonce = nonce + 1
        } else {
            expectNonce = state.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.addressCost[address]
        if exist {
            addressesBalance[address] = new(big.Int).Sub(state.GetBalance(address), cost)
        } else {
            addressesBalance[address] = state.GetBalance(address)
        }
    }

    // Validate if balance is enough for TXs in this block.
    blockGasLimit := new(big.Int).SetUint64(d.gov.DexconConfiguration(block.Position.Round).BlockGasLimit)
    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) {

    log.Debug("DexconApp block deliver", "height", result.Height, "hash", blockHash, "position", blockPosition.String())
    defer log.Debug("DexconApp block delivered", "height", result.Height, "hash", blockHash, "position", blockPosition.String())

    d.appMu.Lock()
    defer d.appMu.Unlock()

    block, txs := d.getConfirmedBlockByHash(blockHash)
    if block == nil {
        panic("Can not get confirmed block")
    }

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

    var owner common.Address
    if !block.IsEmpty() {
        gs := d.gov.GetStateForConfigAtRound(block.Position.Round)
        node, err := gs.GetNodeByID(block.ProposerID)
        if err != nil {
            panic(err)
        }
        owner = node.Owner
    }

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

    if block.IsEmpty() {
        _, err = d.blockchain.ProcessEmptyBlock(newBlock)
        if err != nil {
            log.Error("Failed to process empty block", "error", err)
            panic(err)
        }
    } else {
        _, err = d.blockchain.ProcessBlock(newBlock, &block.Witness)
        if err != nil {
            log.Error("Failed to process pending block", "error", err)
            panic(err)
        }
    }

    d.removeConfirmedBlock(blockHash)
    d.deliveredHeight = result.Height

    // New blocks are finalized, notify other components.
    go d.finalizedBlockFeed.Send(core.NewFinalizedBlockEvent{Block: d.blockchain.CurrentBlock()})
}

// BlockConfirmed is called when a block is confirmed.
func (d *DexconApp) BlockConfirmed(block coreTypes.Block) {
    d.appMu.Lock()
    defer d.appMu.Unlock()

    log.Debug("DexconApp block confirmed", "block", block.String())
    if err := d.addConfirmedBlock(&block); err != nil {
        panic(err)
    }
}

type addressInfo struct {
    cost *big.Int
}

type blockInfo struct {
    addresses map[common.Address]*addressInfo
    block     *coreTypes.Block
    txs       types.Transactions
}

func (d *DexconApp) addConfirmedBlock(block *coreTypes.Block) error {
    var transactions types.Transactions
    if len(block.Payload) != 0 {
        err := rlp.Decode(bytes.NewReader(block.Payload), &transactions)
        if err != nil {
            return err
        }
        _, err = types.GlobalSigCache.Add(types.NewEIP155Signer(d.blockchain.Config().ChainID), transactions)
        if err != nil {
            return err
        }
    }

    addressMap := map[common.Address]*addressInfo{}
    for _, tx := range transactions {
        msg, err := tx.AsMessage(types.MakeSigner(d.blockchain.Config(), new(big.Int)))
        if err != nil {
            return err
        }

        if addrInfo, exist := addressMap[msg.From()]; !exist {
            addressMap[msg.From()] = &addressInfo{cost: tx.Cost()}
        } else {
            addrInfo.cost = new(big.Int).Add(addrInfo.cost, tx.Cost())
        }

        // get latest nonce in block
        if nonce, exist := d.addressNonce[msg.From()]; !exist || nonce < msg.Nonce() {
            d.addressNonce[msg.From()] = msg.Nonce()
        } else {
            return fmt.Errorf("address %v nonce incorrect cached(%d) >= tx(%d)", msg.From(), nonce, msg.Nonce())
        }

        // calculate max cost in confirmed blocks
        if d.addressCost[msg.From()] == nil {
            d.addressCost[msg.From()] = big.NewInt(0)
        }
        d.addressCost[msg.From()] = new(big.Int).Add(d.addressCost[msg.From()], tx.Cost())
    }

    for addr := range addressMap {
        d.addressCounter[addr]++
    }

    d.confirmedBlocks[block.Hash] = &blockInfo{
        addresses: addressMap,
        block:     block,
        txs:       transactions,
    }

    d.undeliveredNum++
    return nil
}

func (d *DexconApp) removeConfirmedBlock(hash coreCommon.Hash) {
    blockInfo := d.confirmedBlocks[hash]
    for addr, info := range blockInfo.addresses {
        d.addressCounter[addr]--
        d.addressCost[addr] = new(big.Int).Sub(d.addressCost[addr], info.cost)
        if d.addressCounter[addr] == 0 {
            delete(d.addressCounter, addr)
            delete(d.addressCost, addr)
            delete(d.addressNonce, addr)
        }
    }

    delete(d.confirmedBlocks, hash)
    d.undeliveredNum--
}

func (d *DexconApp) getConfirmedBlockByHash(hash coreCommon.Hash) (*coreTypes.Block, types.Transactions) {
    info, exist := d.confirmedBlocks[hash]
    if !exist {
        return nil, nil
    }

    return info.block, info.txs
}

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()
}