path: root/dex/app.go

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

package dex

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

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

    "github.com/dexon-foundation/dexon/common"
    "github.com/dexon-foundation/dexon/core"
    "github.com/dexon-foundation/dexon/core/state"
    "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"
)

// 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

    notifyChan map[uint64]*notify
    mutex      *sync.Mutex

    lastPendingHeight uint64
    insertMu          sync.Mutex

    chainHeight map[uint32]uint64
}

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,
        notifyChan:  make(map[uint64]*notify),
        mutex:       &sync.Mutex{},
        chainHeight: make(map[uint32]uint64),
    }
}

func (d *DexconApp) addNotify(height uint64) <-chan uint64 {
    d.mutex.Lock()
    defer d.mutex.Unlock()
    result := make(chan uint64)
    if n, exist := d.notifyChan[height]; exist {
        n.results = append(n.results, result)
    } else {
        d.notifyChan[height] = &notify{}
        d.notifyChan[height].results = append(d.notifyChan[height].results, result)
    }
    return result
}

func (d *DexconApp) notify(height uint64) {
    d.mutex.Lock()
    defer d.mutex.Unlock()
    for h, n := range d.notifyChan {
        if height >= h {
            for _, ch := range n.results {
                ch <- height
            }
            delete(d.notifyChan, h)
        }
    }
    d.lastPendingHeight = height
}

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

// PreparePayload is called when consensus core is preparing payload for block.
func (d *DexconApp) PreparePayload(position coreTypes.Position) (payload []byte, err error) {
    d.insertMu.Lock()
    defer d.insertMu.Unlock()
    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)))
    var allTxs types.Transactions
    for addr, txs := range txsMap {
        // every address's transactions will appear in fixed chain
        if !d.checkChain(addr, chainNums, chainID) {
            continue
        }

        var stateDB *state.StateDB
        if d.lastPendingHeight > 0 {
            stateDB, err = d.blockchain.StateAt(d.blockchain.GetPendingBlockByHeight(d.lastPendingHeight).Root())
            if err != nil {
                return nil, fmt.Errorf("PreparePayload d.blockchain.StateAt err %v", err)
            }
        } else {
            stateDB, err = d.blockchain.State()
            if err != nil {
                return nil, fmt.Errorf("PreparePayload d.blockchain.State err %v", err)
            }
        }

        for _, tx := range txs {
            if tx.Nonce() != stateDB.GetNonce(addr) {
                log.Debug("Break transaction", "tx.hash", tx.Hash(), "nonce", tx.Nonce(), "expect", stateDB.GetNonce(addr))
                break
            }
            log.Debug("Receive transaction", "tx.hash", tx.Hash(), "nonce", tx.Nonce(), "amount", tx.Value())
            allTxs = append(allTxs, tx)
        }
    }
    payload, err = rlp.EncodeToBytes(&allTxs)
    if err != nil {
        return
    }

    return
}

// 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.lastPendingHeight == 0 && consensusHeight == 0 {
        witnessBlock = d.blockchain.CurrentBlock()
    } else if d.lastPendingHeight >= consensusHeight {
        witnessBlock = d.blockchain.GetPendingBlockByHeight(d.lastPendingHeight)
    } else if h := <-d.addNotify(consensusHeight); h >= consensusHeight {
        witnessBlock = d.blockchain.GetPendingBlockByHeight(h)
    } 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{
        Timestamp: time.Unix(witnessBlock.Time().Int64(), 0),
        Height:    witnessBlock.NumberU64(),
        Data:      witnessData,
    }, nil
}

// VerifyBlock verifies if the payloads are valid.
func (d *DexconApp) VerifyBlock(block *coreTypes.Block) bool {
    d.insertMu.Lock()
    defer d.insertMu.Unlock()

    var witnessData witnessData
    err := rlp.Decode(bytes.NewReader(block.Witness.Data), &witnessData)
    if err != nil {
        log.Error("Witness rlp decode", "error", err)
        return false
    }

    // check witness root exist
    _, err = d.blockchain.StateAt(witnessData.Root)
    if err != nil {
        log.Error("Get state root error", "err", err)
        return false
    }

    if block.Position.Height != 0 {
        chainLastHeight, empty := d.blockchain.GetChainLastConfirmedHeight(block.Position.ChainID)
        if empty {
            var exist bool
            chainLastHeight, exist = d.chainHeight[block.Position.ChainID]
            if !exist {
                log.Error("Something wrong")
                return false
            }
        }

        // check if chain block height is sequential
        if chainLastHeight != block.Position.Height-1 {
            log.Error("Check confirmed block height fail", "chain", block.Position.ChainID, "height", block.Position.Height-1)
            return false
        }
    }

    // set state to the pending height
    var latestState *state.StateDB
    if d.lastPendingHeight == 0 {
        latestState, err = d.blockchain.State()
        if err != nil {
            log.Error("Get current state", "error", err)
            return false
        }
    } else {
        latestState, err = d.blockchain.StateAt(d.blockchain.GetPendingBlockByHeight(d.lastPendingHeight).Root())
        if err != nil {
            log.Error("Get pending state", "error", err)
            return false
        }
    }

    var transactions types.Transactions
    err = rlp.Decode(bytes.NewReader(block.Payload), &transactions)
    if err != nil {
        log.Error("Payload rlp decode", "error", err)
        return false
    }

    // check if nonce is sequential and return first nonce of every address
    addresses, err := d.validateNonce(transactions)
    if err != nil {
        log.Error("Get address nonce", "error", err)
        return false
    }

    // check all address nonce
    chainID := big.NewInt(int64(block.Position.ChainID))
    chainNums := new(big.Int).SetUint64(uint64(d.gov.GetNumChains(block.Position.Round)))
    for address, firstNonce := range addresses {
        if !d.checkChain(address, chainNums, chainID) {
            log.Error("check chain fail", "address", address)
            return false
        }

        var expectNonce uint64
        // get last nonce from confirmed blocks
        lastConfirmedNonce, empty, err := d.blockchain.GetLastNonceFromConfirmedBlocks(block.Position.ChainID, address)
        if err != nil {
            log.Error("Get last nonce from confirmed blocks", "error", err)
            return false
        } else if empty {
            // get expect nonce from latest state when confirmed block is empty
            expectNonce = latestState.GetNonce(address)
        } else {
            expectNonce = lastConfirmedNonce + 1
        }

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

    // get balance from state
    addressesBalance := map[common.Address]*big.Int{}
    for address := range addresses {
        addressesBalance[address] = latestState.GetBalance(address)
    }

    // replay confirmed block tx to correct balance
    confirmedBlocks := d.blockchain.GetConfirmedBlocksByChainID(block.Position.ChainID)
    for _, block := range confirmedBlocks {
        var txs types.Transactions
        err := rlp.Decode(bytes.NewReader(block.Payload), &txs)
        if err != nil {
            log.Error("Decode confirmed block", "error", err)
            return false
        }

        for _, tx := range txs {
            msg, err := tx.AsMessage(types.MakeSigner(d.blockchain.Config(), new(big.Int)))
            if err != nil {
                log.Error("Tx to message", "error", err)
                return false
            }

            balance, exist := addressesBalance[msg.From()]
            if exist {
                maxGasUsed := new(big.Int).Mul(new(big.Int).SetUint64(msg.Gas()), msg.GasPrice())
                balance = new(big.Int).Sub(balance, maxGasUsed)
                if balance.Cmp(big.NewInt(0)) <= 0 {
                    log.Error("Replay confirmed tx fail", "reason", "not enough balance")
                    return false
                }
                addressesBalance[msg.From()] = balance
            }
        }
    }

    // validate tx to check available balance
    for _, tx := range transactions {
        msg, err := tx.AsMessage(types.MakeSigner(d.blockchain.Config(), new(big.Int)))
        if err != nil {
            log.Error("Tx to message", "error", err)
            return false
        }
        balance, _ := addressesBalance[msg.From()]
        maxGasUsed := new(big.Int).Mul(new(big.Int).SetUint64(msg.Gas()), msg.GasPrice())
        balance = new(big.Int).Sub(balance, maxGasUsed)
        if balance.Cmp(big.NewInt(0)) <= 0 {
            log.Error("Tx fail", "reason", "not enough balance")
            return false
        }
        addressesBalance[msg.From()] = balance
    }

    return true
}

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

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

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

    var witnessData witnessData
    err = rlp.Decode(bytes.NewReader(block.Witness.Data), &witnessData)
    if err != nil {
        log.Error("Witness rlp decode failed", "error", err)
        panic(err)
    }

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

    log.Debug("Block proposer id", "hash", block.ProposerID)
    newBlock := types.NewBlock(&types.Header{
        Number:             new(big.Int).SetUint64(result.Height),
        Time:               big.NewInt(result.Timestamp.Unix()),
        Coinbase:           common.BytesToAddress(block.ProposerID.Bytes()),
        Position:           block.Position,
        WitnessHeight:      block.Witness.Height,
        WitnessRoot:        witnessData.Root,
        WitnessReceiptHash: witnessData.ReceiptHash,
        ChainID:            block.Position.ChainID,
        ChainBlockHeight:   block.Position.Height,
        // TODO(bojie): fix it
        GasLimit:   8000000,
        DexconMeta: dexconMeta,
        Difficulty: big.NewInt(1),
    }, transactions, nil, nil)

    _, err = d.blockchain.InsertPendingBlocks([]*types.Block{newBlock})
    if err != nil {
        log.Error("Insert chain", "error", err)
        panic(err)
    }

    log.Debug("Insert pending block success", "height", result.Height)
    d.chainHeight[block.Position.ChainID] = block.Position.Height
    d.blockchain.RemoveConfirmedBlock(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.blockchain.AddConfirmedBlock(&block)
}

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()
            continue
        } else {
            addressNonce[msg.From()] = msg.Nonce()
            addressFirstNonce[msg.From()] = msg.Nonce()
        }
    }

    return addressFirstNonce, nil
}