path: root/core/consensus.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 core

import (
    "context"
    "fmt"
    "log"
    "sync"
    "time"

    "github.com/dexon-foundation/dexon-consensus-core/common"
    "github.com/dexon-foundation/dexon-consensus-core/core/blockdb"
    "github.com/dexon-foundation/dexon-consensus-core/core/crypto"
    "github.com/dexon-foundation/dexon-consensus-core/core/types"
)

// Errors for consensus core.
var (
    ErrProposerNotInNodeSet = fmt.Errorf(
        "proposer is not in node set")
    ErrIncorrectHash = fmt.Errorf(
        "hash of block is incorrect")
    ErrIncorrectSignature = fmt.Errorf(
        "signature of block is incorrect")
    ErrGenesisBlockNotEmpty = fmt.Errorf(
        "genesis block should be empty")
    ErrUnknownBlockProposed = fmt.Errorf(
        "unknown block is proposed")
    ErrUnknownBlockConfirmed = fmt.Errorf(
        "unknown block is confirmed")
)

// consensusBAReceiver implements agreementReceiver.
type consensusBAReceiver struct {
    // TODO(mission): consensus would be replaced by lattice and network.
    consensus        *Consensus
    agreementModule  *agreement
    chainID          uint32
    changeNotaryTime time.Time
    restartNotary    chan bool
}

func (recv *consensusBAReceiver) ProposeVote(vote *types.Vote) {
    if err := recv.agreementModule.prepareVote(vote); err != nil {
        log.Println(err)
        return
    }
    go func() {
        if err := recv.agreementModule.processVote(vote); err != nil {
            log.Println(err)
            return
        }
        recv.consensus.network.BroadcastVote(vote)
    }()
}

func (recv *consensusBAReceiver) ProposeBlock() {
    block := recv.consensus.proposeBlock(recv.chainID)
    recv.consensus.baModules[recv.chainID].addCandidateBlock(block)
    if err := recv.consensus.preProcessBlock(block); err != nil {
        log.Println(err)
        return
    }
    recv.consensus.network.BroadcastBlock(block)
}

func (recv *consensusBAReceiver) ConfirmBlock(hash common.Hash) {
    block, exist := recv.consensus.baModules[recv.chainID].findCandidateBlock(hash)
    if !exist {
        log.Println(ErrUnknownBlockConfirmed, hash)
        return
    }
    if err := recv.consensus.processBlock(block); err != nil {
        log.Println(err)
        return
    }
    recv.restartNotary <- block.Timestamp.After(recv.changeNotaryTime)
}

// consensusDKGReceiver implements dkgReceiver.
type consensusDKGReceiver struct {
    ID           types.NodeID
    gov          Governance
    authModule   *Authenticator
    nodeSetCache *NodeSetCache
    network      Network
}

// ProposeDKGComplaint proposes a DKGComplaint.
func (recv *consensusDKGReceiver) ProposeDKGComplaint(
    complaint *types.DKGComplaint) {
    if err := recv.authModule.SignDKGComplaint(complaint); err != nil {
        log.Println(err)
        return
    }
    recv.gov.AddDKGComplaint(complaint)
}

// ProposeDKGMasterPublicKey propose a DKGMasterPublicKey.
func (recv *consensusDKGReceiver) ProposeDKGMasterPublicKey(
    mpk *types.DKGMasterPublicKey) {
    if err := recv.authModule.SignDKGMasterPublicKey(mpk); err != nil {
        log.Println(err)
        return
    }
    recv.gov.AddDKGMasterPublicKey(mpk)
}

// ProposeDKGPrivateShare propose a DKGPrivateShare.
func (recv *consensusDKGReceiver) ProposeDKGPrivateShare(
    prv *types.DKGPrivateShare) {
    if err := recv.authModule.SignDKGPrivateShare(prv); err != nil {
        log.Println(err)
        return
    }
    receiverPubKey, exists := recv.nodeSetCache.GetPublicKey(prv.ReceiverID)
    if !exists {
        log.Println("public key for receiver not found")
        return
    }
    recv.network.SendDKGPrivateShare(receiverPubKey, prv)
}

// ProposeDKGAntiNackComplaint propose a DKGPrivateShare as an anti complaint.
func (recv *consensusDKGReceiver) ProposeDKGAntiNackComplaint(
    prv *types.DKGPrivateShare) {
    if prv.ProposerID == recv.ID {
        if err := recv.authModule.SignDKGPrivateShare(prv); err != nil {
            log.Println(err)
            return
        }
    }
    recv.network.BroadcastDKGPrivateShare(prv)
}

// Consensus implements DEXON Consensus algorithm.
type Consensus struct {
    // Node Info.
    ID            types.NodeID
    authModule    *Authenticator
    currentConfig *types.Config

    // Modules.
    nbModule *nonBlocking

    // BA.
    baModules []*agreement
    receivers []*consensusBAReceiver

    // DKG.
    dkgRunning int32
    dkgReady   *sync.Cond
    cfgModule  *configurationChain

    // Dexon consensus v1's modules.
    lattice  *Lattice
    ccModule *compactionChain

    // Interfaces.
    db        blockdb.BlockDatabase
    gov       Governance
    network   Network
    tickerObj Ticker

    // Misc.
    nodeSetCache *NodeSetCache
    round        uint64
    lock         sync.RWMutex
    ctx          context.Context
    ctxCancel    context.CancelFunc
}

// NewConsensus construct an Consensus instance.
func NewConsensus(
    app Application,
    gov Governance,
    db blockdb.BlockDatabase,
    network Network,
    prv crypto.PrivateKey) *Consensus {

    // TODO(w): load latest blockHeight from DB, and use config at that height.
    var round uint64
    config := gov.Configuration(round)
    // TODO(w): notarySet is different for each chain, need to write a
    // GetNotarySetForChain(nodeSet, chainID, crs) function to get the
    // correct notary set for a given chain.
    nodeSetCache := NewNodeSetCache(gov)
    crs := gov.CRS(round)
    // Setup acking by information returned from Governace.
    nodes, err := nodeSetCache.GetNodeSet(0)
    if err != nil {
        panic(err)
    }
    // Setup context.
    ctx, ctxCancel := context.WithCancel(context.Background())
    // Setup auth module.
    authModule := NewAuthenticator(prv)
    // Check if the application implement Debug interface.
    debugApp, _ := app.(Debug)
    // Setup nonblocking module.
    nbModule := newNonBlocking(app, debugApp)
    // Init lattice.
    lattice := NewLattice(config, authModule, nbModule, nbModule, db)
    // Init configuration chain.
    ID := types.NewNodeID(prv.PublicKey())
    cfgModule := newConfigurationChain(
        ID,
        &consensusDKGReceiver{
            ID:           ID,
            gov:          gov,
            authModule:   authModule,
            nodeSetCache: nodeSetCache,
            network:      network,
        },
        gov)
    // Register DKG for the initial round. This is a temporary function call for
    // simulation.
    cfgModule.registerDKG(0, config.NumDKGSet/3)
    // Construct Consensus instance.
    con := &Consensus{
        ID:            ID,
        currentConfig: config,
        ccModule:      newCompactionChain(db),
        lattice:       lattice,
        nbModule:      nbModule,
        gov:           gov,
        db:            db,
        network:       network,
        tickerObj:     newTicker(gov, 0, TickerBA),
        dkgReady:      sync.NewCond(&sync.Mutex{}),
        cfgModule:     cfgModule,
        nodeSetCache:  nodeSetCache,
        ctx:           ctx,
        ctxCancel:     ctxCancel,
        authModule:    authModule,
    }

    con.baModules = make([]*agreement, config.NumChains)
    con.receivers = make([]*consensusBAReceiver, config.NumChains)
    for i := uint32(0); i < config.NumChains; i++ {
        chainID := i
        recv := &consensusBAReceiver{
            consensus:     con,
            chainID:       chainID,
            restartNotary: make(chan bool, 1),
        }
        agreementModule := newAgreement(
            con.ID,
            recv,
            nodes.IDs,
            newLeaderSelector(crs),
            con.authModule,
        )
        // Hacky way to make agreement module self contained.
        recv.agreementModule = agreementModule
        con.baModules[chainID] = agreementModule
        con.receivers[chainID] = recv
    }
    return con
}

// Run starts running DEXON Consensus.
func (con *Consensus) Run() {
    go con.processMsg(con.network.ReceiveChan())
    con.runDKGTSIG()
    func() {
        con.dkgReady.L.Lock()
        defer con.dkgReady.L.Unlock()
        for con.dkgRunning != 2 {
            con.dkgReady.Wait()
        }
    }()
    ticks := make([]chan struct{}, 0, con.currentConfig.NumChains)
    for i := uint32(0); i < con.currentConfig.NumChains; i++ {
        tick := make(chan struct{})
        ticks = append(ticks, tick)
        go con.runBA(i, tick)
    }
    go con.runCRS()

    // Reset ticker.
    <-con.tickerObj.Tick()
    <-con.tickerObj.Tick()
    for {
        <-con.tickerObj.Tick()
        for _, tick := range ticks {
            go func(tick chan struct{}) { tick <- struct{}{} }(tick)
        }
    }
}

func (con *Consensus) runBA(chainID uint32, tick <-chan struct{}) {
    // TODO(jimmy-dexon): move this function inside agreement.
    agreement := con.baModules[chainID]
    recv := con.receivers[chainID]
    recv.changeNotaryTime = time.Now().UTC()
    recv.restartNotary <- true
    nIDs := make(map[types.NodeID]struct{})
    // Reset ticker
    <-tick
BALoop:
    for {
        select {
        case <-con.ctx.Done():
            break BALoop
        default:
        }
        for i := 0; i < agreement.clocks(); i++ {
            <-tick
        }
        select {
        case newNotary := <-recv.restartNotary:
            if newNotary {
                recv.changeNotaryTime.Add(con.currentConfig.RoundInterval)
                nodes, err := con.nodeSetCache.GetNodeSet(con.round)
                if err != nil {
                    panic(err)
                }
                nIDs = nodes.GetSubSet(con.gov.Configuration(con.round).NumNotarySet,
                    types.NewNotarySetTarget(con.gov.CRS(con.round), chainID))
            }
            agreement.restart(nIDs, con.lattice.NextPosition(chainID))
        default:
        }
        err := agreement.nextState()
        if err != nil {
            log.Printf("[%s] %s\n", con.ID.String(), err)
            break BALoop
        }
    }
}

// runDKGTSIG starts running DKG+TSIG protocol.
func (con *Consensus) runDKGTSIG() {
    con.dkgReady.L.Lock()
    defer con.dkgReady.L.Unlock()
    if con.dkgRunning != 0 {
        return
    }
    con.dkgRunning = 1
    go func() {
        startTime := time.Now().UTC()
        defer func() {
            con.dkgReady.L.Lock()
            defer con.dkgReady.L.Unlock()
            con.dkgReady.Broadcast()
            con.dkgRunning = 2
            DKGTime := time.Now().Sub(startTime)
            if DKGTime.Nanoseconds() >=
                con.currentConfig.RoundInterval.Nanoseconds()/2 {
                log.Printf("[%s] WARNING!!! Your computer cannot finish DKG on time!\n",
                    con.ID)
            }
        }()
        round := con.round
        if err := con.cfgModule.runDKG(round); err != nil {
            panic(err)
        }
        nodes, err := con.nodeSetCache.GetNodeSet(round)
        if err != nil {
            panic(err)
        }
        hash := HashConfigurationBlock(
            nodes.IDs,
            con.gov.Configuration(round),
            common.Hash{},
            con.cfgModule.prevHash)
        psig, err := con.cfgModule.preparePartialSignature(
            round, hash, types.TSigConfigurationBlock)
        if err != nil {
            panic(err)
        }
        if err = con.authModule.SignDKGPartialSignature(psig); err != nil {
            panic(err)
        }
        if err = con.cfgModule.processPartialSignature(psig); err != nil {
            panic(err)
        }
        con.network.BroadcastDKGPartialSignature(psig)
        if _, err = con.cfgModule.runBlockTSig(round, hash); err != nil {
            panic(err)
        }
    }()
}

func (con *Consensus) runCRS() {
    for {
        ticker := newTicker(con.gov, con.round, TickerCRS)
        select {
        case <-con.ctx.Done():
            return
        default:
        }
        <-ticker.Tick()
        // Start running next round CRS.
        psig, err := con.cfgModule.preparePartialSignature(
            con.round, con.gov.CRS(con.round), types.TSigCRS)
        if err != nil {
            log.Println(err)
        } else if err = con.authModule.SignDKGPartialSignature(psig); err != nil {
            log.Println(err)
        } else if err = con.cfgModule.processPartialSignature(psig); err != nil {
            log.Println(err)
        } else {
            con.network.BroadcastDKGPartialSignature(psig)
            crs, err := con.cfgModule.runCRSTSig(con.round, con.gov.CRS(con.round))
            if err != nil {
                log.Println(err)
            } else {
                con.gov.ProposeCRS(con.round+1, crs)
            }
        }
        con.cfgModule.registerDKG(con.round+1, con.currentConfig.NumDKGSet/3)
        <-ticker.Tick()
        // Change round.
        con.round++
        con.currentConfig = con.gov.Configuration(con.round)
        func() {
            con.dkgReady.L.Lock()
            defer con.dkgReady.L.Unlock()
            con.dkgRunning = 0
        }()
        con.runDKGTSIG()
    }
}

// Stop the Consensus core.
func (con *Consensus) Stop() {
    con.ctxCancel()
}

func (con *Consensus) processMsg(msgChan <-chan interface{}) {
    for {
        var msg interface{}
        select {
        case msg = <-msgChan:
        case <-con.ctx.Done():
            return
        }

        switch val := msg.(type) {
        case *types.Block:
            if err := con.preProcessBlock(val); err != nil {
                log.Println(err)
            }
        case *types.Vote:
            if err := con.ProcessVote(val); err != nil {
                log.Println(err)
            }
        case *types.DKGPrivateShare:
            if err := con.cfgModule.processPrivateShare(val); err != nil {
                log.Println(err)
            }

        case *types.DKGPartialSignature:
            if err := con.cfgModule.processPartialSignature(val); err != nil {
                log.Println(err)
            }
        }
    }
}

func (con *Consensus) proposeBlock(chainID uint32) *types.Block {
    block := &types.Block{
        Position: types.Position{
            ChainID: chainID,
        },
    }
    if err := con.prepareBlock(block, time.Now().UTC()); err != nil {
        log.Println(err)
        return nil
    }
    return block
}

// ProcessVote is the entry point to submit ont vote to a Consensus instance.
func (con *Consensus) ProcessVote(vote *types.Vote) (err error) {
    v := vote.Clone()
    err = con.baModules[v.Position.ChainID].processVote(v)
    return err
}

// preProcessBlock performs Byzantine Agreement on the block.
func (con *Consensus) preProcessBlock(b *types.Block) (err error) {
    if err = con.lattice.SanityCheck(b); err != nil {
        return
    }
    if err = con.baModules[b.Position.ChainID].processBlock(b); err != nil {
        return err
    }
    return
}

// processBlock is the entry point to submit one block to a Consensus instance.
func (con *Consensus) processBlock(block *types.Block) (err error) {
    verifiedBlocks, deliveredBlocks, err := con.lattice.ProcessBlock(block)
    if err != nil {
        return
    }
    // Pass verified blocks (pass sanity check) back to BA module.
    for _, b := range verifiedBlocks {
        if err :=
            con.baModules[b.Position.ChainID].processBlock(b); err != nil {
            return err
        }
    }
    // Pass delivered blocks to compaction chain.
    for _, b := range deliveredBlocks {
        if err = con.ccModule.processBlock(b); err != nil {
            return
        }
        if err = con.db.Update(*b); err != nil {
            return
        }
        con.nbModule.BlockDelivered(*b)
        // TODO(mission): Find a way to safely recycle the block.
        //                We should deliver block directly to
        //                nonBlocking and let them recycle the
        //                block.
    }
    return
}

// PrepareBlock would setup header fields of block based on its ProposerID.
func (con *Consensus) prepareBlock(b *types.Block,
    proposeTime time.Time) (err error) {
    if err = con.lattice.PrepareBlock(b, proposeTime); err != nil {
        return
    }
    // TODO(mission): decide CRS by block's round, which could be determined by
    //                block's info (ex. position, timestamp).
    if err = con.authModule.SignCRS(b, con.gov.CRS(0)); err != nil {
        return
    }
    return
}

// PrepareGenesisBlock would setup header fields for genesis block.
func (con *Consensus) PrepareGenesisBlock(b *types.Block,
    proposeTime time.Time) (err error) {
    if err = con.prepareBlock(b, proposeTime); err != nil {
        return
    }
    if len(b.Payload) != 0 {
        err = ErrGenesisBlockNotEmpty
        return
    }
    return
}