path: root/core/configuration-chain.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 core

import (
    "fmt"
    "sync"
    "time"

    "github.com/dexon-foundation/dexon-consensus/common"
    "github.com/dexon-foundation/dexon-consensus/core/crypto"
    "github.com/dexon-foundation/dexon-consensus/core/types"
    typesDKG "github.com/dexon-foundation/dexon-consensus/core/types/dkg"
    "github.com/dexon-foundation/dexon-consensus/core/utils"
)

// Errors for configuration chain..
var (
    ErrDKGNotRegistered = fmt.Errorf(
        "not yet registered in DKG protocol")
    ErrTSigAlreadyRunning = fmt.Errorf(
        "tsig is already running")
    ErrDKGNotReady = fmt.Errorf(
        "DKG is not ready")
)

type configurationChain struct {
    ID              types.NodeID
    recv            dkgReceiver
    gov             Governance
    dkg             *dkgProtocol
    logger          common.Logger
    dkgLock         sync.RWMutex
    dkgSigner       map[uint64]*dkgShareSecret
    gpk             map[uint64]*DKGGroupPublicKey
    dkgResult       sync.RWMutex
    tsig            map[common.Hash]*tsigProtocol
    tsigTouched     map[common.Hash]struct{}
    tsigReady       *sync.Cond
    cache           *utils.NodeSetCache
    dkgSet          map[types.NodeID]struct{}
    mpkReady        bool
    pendingPrvShare map[types.NodeID]*typesDKG.PrivateShare
    // TODO(jimmy-dexon): add timeout to pending psig.
    pendingPsig map[common.Hash][]*typesDKG.PartialSignature
    prevHash    common.Hash
}

func newConfigurationChain(
    ID types.NodeID,
    recv dkgReceiver,
    gov Governance,
    cache *utils.NodeSetCache,
    logger common.Logger) *configurationChain {
    return &configurationChain{
        ID:          ID,
        recv:        recv,
        gov:         gov,
        logger:      logger,
        dkgSigner:   make(map[uint64]*dkgShareSecret),
        gpk:         make(map[uint64]*DKGGroupPublicKey),
        tsig:        make(map[common.Hash]*tsigProtocol),
        tsigTouched: make(map[common.Hash]struct{}),
        tsigReady:   sync.NewCond(&sync.Mutex{}),
        cache:       cache,
        pendingPsig: make(map[common.Hash][]*typesDKG.PartialSignature),
    }
}

func (cc *configurationChain) registerDKG(round uint64, threshold int) {
    cc.dkgLock.Lock()
    defer cc.dkgLock.Unlock()
    if cc.dkg != nil {
        cc.logger.Error("Previous DKG is not finished")
    }
    dkgSet, err := cc.cache.GetDKGSet(round)
    if err != nil {
        cc.logger.Error("Error getting DKG set from cache", "error", err)
        return
    }
    cc.dkgSet = dkgSet
    cc.pendingPrvShare = make(map[types.NodeID]*typesDKG.PrivateShare)
    cc.mpkReady = false
    cc.dkg = newDKGProtocol(
        cc.ID,
        cc.recv,
        round,
        threshold)
}

func (cc *configurationChain) runDKG(round uint64) error {
    cc.dkgLock.Lock()
    defer cc.dkgLock.Unlock()
    if cc.dkg == nil || cc.dkg.round != round {
        if cc.dkg != nil && cc.dkg.round > round {
            cc.logger.Warn("DKG canceled", "round", round)
            return nil
        }
        return ErrDKGNotRegistered
    }
    if func() bool {
        cc.dkgResult.RLock()
        defer cc.dkgResult.RUnlock()
        _, exist := cc.gpk[round]
        return exist
    }() {
        return nil
    }
    cc.logger.Debug("Calling Governance.IsDKGFinal", "round", round)
    if cc.gov.IsDKGFinal(round) {
        cc.logger.Warn("DKG already final", "round", round)
        return nil
    }

    ticker := newTicker(cc.gov, round, TickerDKG)
    cc.dkgLock.Unlock()
    <-ticker.Tick()
    cc.dkgLock.Lock()
    // Phase 2(T = 0): Exchange DKG secret key share.
    cc.logger.Debug("Calling Governance.DKGMasterPublicKeys", "round", round)
    cc.dkg.processMasterPublicKeys(cc.gov.DKGMasterPublicKeys(round))
    cc.mpkReady = true
    for _, prvShare := range cc.pendingPrvShare {
        if err := cc.dkg.processPrivateShare(prvShare); err != nil {
            cc.logger.Error("Failed to process private share",
                "error", err)
        }
    }
    // Phase 3(T = 0~λ): Propose complaint.
    // Propose complaint is done in `processMasterPublicKeys`.
    cc.dkgLock.Unlock()
    <-ticker.Tick()
    cc.dkgLock.Lock()
    // Phase 4(T = λ): Propose nack complaints.
    cc.dkg.proposeNackComplaints()
    cc.dkgLock.Unlock()
    <-ticker.Tick()
    cc.dkgLock.Lock()
    // Phase 5(T = 2λ): Propose Anti nack complaint.
    cc.logger.Debug("Calling Governance.DKGComplaints", "round", round)
    cc.dkg.processNackComplaints(cc.gov.DKGComplaints(round))
    cc.dkgLock.Unlock()
    <-ticker.Tick()
    cc.dkgLock.Lock()
    // Phase 6(T = 3λ): Rebroadcast anti nack complaint.
    // Rebroadcast is done in `processPrivateShare`.
    cc.dkgLock.Unlock()
    <-ticker.Tick()
    cc.dkgLock.Lock()
    // Phase 7(T = 4λ): Enforce complaints and nack complaints.
    cc.logger.Debug("Calling Governance.DKGComplaints", "round", round)
    cc.dkg.enforceNackComplaints(cc.gov.DKGComplaints(round))
    // Enforce complaint is done in `processPrivateShare`.
    // Phase 8(T = 5λ): DKG finalize.
    cc.dkgLock.Unlock()
    <-ticker.Tick()
    cc.dkgLock.Lock()
    cc.dkg.proposeFinalize()
    // Phase 9(T = 6λ): DKG is ready.
    cc.dkgLock.Unlock()
    <-ticker.Tick()
    cc.dkgLock.Lock()
    // Normally, IsDKGFinal would return true here. Use this for in case of
    // unexpected network fluctuation and ensure the robustness of DKG protocol.
    cc.logger.Debug("Calling Governance.IsDKGFinal", "round", round)
    for !cc.gov.IsDKGFinal(round) {
        cc.logger.Info("DKG is not ready yet. Try again later...",
            "nodeID", cc.ID)
        time.Sleep(500 * time.Millisecond)
    }
    cc.logger.Debug("Calling Governance.DKGMasterPublicKeys", "round", round)
    cc.logger.Debug("Calling Governance.DKGComplaints", "round", round)
    gpk, err := NewDKGGroupPublicKey(round,
        cc.gov.DKGMasterPublicKeys(round),
        cc.gov.DKGComplaints(round),
        cc.dkg.threshold)
    if err != nil {
        return err
    }
    qualifies := ""
    for nID := range gpk.qualifyNodeIDs {
        qualifies += fmt.Sprintf("%s ", nID.String()[:6])
    }
    cc.logger.Info("Qualify Nodes",
        "nodeID", cc.ID,
        "round", round,
        "count", len(gpk.qualifyIDs),
        "qualifies", qualifies)
    if _, exist := gpk.qualifyNodeIDs[cc.ID]; !exist {
        cc.logger.Warn("Self is not in Qualify Nodes")
        return nil
    }
    signer, err := cc.dkg.recoverShareSecret(gpk.qualifyIDs)
    if err != nil {
        return err
    }
    cc.dkgResult.Lock()
    defer cc.dkgResult.Unlock()
    cc.dkgSigner[round] = signer
    cc.gpk[round] = gpk
    return nil
}

func (cc *configurationChain) preparePartialSignature(
    round uint64, hash common.Hash) (*typesDKG.PartialSignature, error) {
    signer, exist := func() (*dkgShareSecret, bool) {
        cc.dkgResult.RLock()
        defer cc.dkgResult.RUnlock()
        signer, exist := cc.dkgSigner[round]
        return signer, exist
    }()
    if !exist {
        return nil, ErrDKGNotReady
    }
    return &typesDKG.PartialSignature{
        ProposerID:       cc.ID,
        Round:            round,
        Hash:             hash,
        PartialSignature: signer.sign(hash),
    }, nil
}

func (cc *configurationChain) touchTSigHash(hash common.Hash) (first bool) {
    cc.tsigReady.L.Lock()
    defer cc.tsigReady.L.Unlock()
    _, exist := cc.tsigTouched[hash]
    cc.tsigTouched[hash] = struct{}{}
    return !exist
}

func (cc *configurationChain) untouchTSigHash(hash common.Hash) {
    cc.tsigReady.L.Lock()
    defer cc.tsigReady.L.Unlock()
    delete(cc.tsigTouched, hash)
}

func (cc *configurationChain) runTSig(
    round uint64, hash common.Hash) (
    crypto.Signature, error) {
    gpk, exist := func() (*DKGGroupPublicKey, bool) {
        cc.dkgResult.RLock()
        defer cc.dkgResult.RUnlock()
        gpk, exist := cc.gpk[round]
        return gpk, exist
    }()
    if !exist {
        return crypto.Signature{}, ErrDKGNotReady
    }
    cc.tsigReady.L.Lock()
    defer cc.tsigReady.L.Unlock()
    if _, exist := cc.tsig[hash]; exist {
        return crypto.Signature{}, ErrTSigAlreadyRunning
    }
    cc.tsig[hash] = newTSigProtocol(gpk, hash)
    pendingPsig := cc.pendingPsig[hash]
    delete(cc.pendingPsig, hash)
    go func() {
        for _, psig := range pendingPsig {
            if err := cc.processPartialSignature(psig); err != nil {
                cc.logger.Error("failed to process partial signature",
                    "nodeID", cc.ID,
                    "error", err)
            }
        }
    }()
    timeout := make(chan struct{}, 1)
    go func() {
        // TODO(jimmy-dexon): make timeout configurable.
        time.Sleep(5 * time.Second)
        timeout <- struct{}{}
        cc.tsigReady.Broadcast()
    }()
    var signature crypto.Signature
    var err error
    for func() bool {
        signature, err = cc.tsig[hash].signature()
        select {
        case <-timeout:
            return false
        default:
        }
        return err == ErrNotEnoughtPartialSignatures
    }() {
        cc.tsigReady.Wait()
    }
    delete(cc.tsig, hash)
    if err != nil {
        return crypto.Signature{}, err
    }
    return signature, nil
}

func (cc *configurationChain) runBlockTSig(
    round uint64, hash common.Hash) (crypto.Signature, error) {
    sig, err := cc.runTSig(round, hash)
    if err != nil {
        return crypto.Signature{}, err
    }
    cc.logger.Info("Block TSIG",
        "nodeID", cc.ID,
        "round", round,
        "signature", sig)
    return sig, nil
}

func (cc *configurationChain) runCRSTSig(
    round uint64, crs common.Hash) ([]byte, error) {
    sig, err := cc.runTSig(round, crs)
    cc.logger.Info("CRS",
        "nodeID", cc.ID,
        "round", round+1,
        "signature", sig)
    return sig.Signature[:], err
}

func (cc *configurationChain) processPrivateShare(
    prvShare *typesDKG.PrivateShare) error {
    cc.dkgLock.Lock()
    defer cc.dkgLock.Unlock()
    if cc.dkg == nil {
        return nil
    }
    if _, exist := cc.dkgSet[prvShare.ProposerID]; !exist {
        return ErrNotDKGParticipant
    }
    if !cc.mpkReady {
        // TODO(jimmy-dexon): remove duplicated signature check in dkg module.
        ok, err := verifyDKGPrivateShareSignature(prvShare)
        if err != nil {
            return err
        }
        if !ok {
            return ErrIncorrectPrivateShareSignature
        }
        cc.pendingPrvShare[prvShare.ProposerID] = prvShare
        return nil
    }
    return cc.dkg.processPrivateShare(prvShare)
}

func (cc *configurationChain) processPartialSignature(
    psig *typesDKG.PartialSignature) error {
    cc.tsigReady.L.Lock()
    defer cc.tsigReady.L.Unlock()
    if _, exist := cc.tsig[psig.Hash]; !exist {
        ok, err := verifyDKGPartialSignatureSignature(psig)
        if err != nil {
            return err
        }
        if !ok {
            return ErrIncorrectPartialSignatureSignature
        }
        cc.pendingPsig[psig.Hash] = append(cc.pendingPsig[psig.Hash], psig)
        return nil
    }
    if err := cc.tsig[psig.Hash].processPartialSignature(psig); err != nil {
        return err
    }
    cc.tsigReady.Broadcast()
    return nil
}