// 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 (
"fmt"
"sync"
"time"
"github.com/dexon-foundation/dexon-consensus-core/blockdb"
"github.com/dexon-foundation/dexon-consensus-core/common"
"github.com/dexon-foundation/dexon-consensus-core/core/types"
"github.com/dexon-foundation/dexon-consensus-core/crypto"
)
// SigToPubFn is a function to recover public key from signature.
type SigToPubFn func(hash common.Hash, signature crypto.Signature) (
crypto.PublicKey, error)
// ErrMissingBlockInfo would be reported if some information is missing when
// calling PrepareBlock. It implements error interface.
type ErrMissingBlockInfo struct {
MissingField string
}
func (e *ErrMissingBlockInfo) Error() string {
return "missing " + e.MissingField + " in block"
}
// Errors for consensus core.
var (
ErrIncorrectHash = fmt.Errorf(
"hash of block is incorrect")
ErrIncorrectSignature = fmt.Errorf(
"signature of block is incorrect")
ErrGenesisBlockNotEmpty = fmt.Errorf(
"genesis block should be empty")
)
// Consensus implements DEXON Consensus algorithm.
type Consensus struct {
app Application
gov Governance
rbModule *reliableBroadcast
toModule *totalOrdering
ctModule *consensusTimestamp
ccModule *compactionChain
db blockdb.BlockDatabase
prvKey crypto.PrivateKey
sigToPub SigToPubFn
lock sync.RWMutex
}
// NewConsensus construct an Consensus instance.
func NewConsensus(
app Application,
gov Governance,
db blockdb.BlockDatabase,
prv crypto.PrivateKey,
sigToPub SigToPubFn) *Consensus {
validatorSet := gov.GetValidatorSet()
// Setup acking by information returned from Governace.
rb := newReliableBroadcast()
for vID := range validatorSet {
rb.addValidator(vID)
}
// Setup sequencer by information returned from Governace.
to := newTotalOrdering(
uint64(gov.GetTotalOrderingK()),
uint64(float32(len(validatorSet)-1)*gov.GetPhiRatio()+1),
uint64(len(validatorSet)))
return &Consensus{
rbModule: rb,
toModule: to,
ctModule: newConsensusTimestamp(),
ccModule: newCompactionChain(),
app: newNonBlockingApplication(app),
gov: gov,
db: db,
prvKey: prv,
sigToPub: sigToPub,
}
}
// sanityCheck checks if the block is a valid block
func (con *Consensus) sanityCheck(blockConv types.BlockConverter) (err error) {
b := blockConv.Block()
// Check the hash of block.
hash, err := hashBlock(blockConv)
if err != nil || hash != b.Hash {
return ErrIncorrectHash
}
// Check the signer.
pubKey, err := con.sigToPub(b.Hash, b.Signature)
if err != nil {
return err
}
if !b.ProposerID.Equal(crypto.Keccak256Hash(pubKey.Bytes())) {
return ErrIncorrectSignature
}
// TODO(jimmy-dexon): remove these comments before open source.
/*
// Check the notary ack.
if notaryBlockHash :=
b.NotaryAck.NotaryBlockHash; (notaryBlockHash != common.Hash{}) {
notaryBlock, err := con.db.Get(notaryBlockHash)
if err != nil {
return err
}
hash, err := hashNotary(¬aryBlock)
if err != nil {
return err
}
pubKey, err := con.sigToPub(hash,
b.NotaryAck.NotarySignature)
if err != nil {
return err
}
if !b.ProposerID.Equal(crypto.Keccak256Hash(pubKey.Bytes())) {
return ErrIncorrectNotaryAck
}
}
*/
return nil
}
// ProcessBlock is the entry point to submit one block to a Consensus instance.
func (con *Consensus) ProcessBlock(blockConv types.BlockConverter) (err error) {
// TODO(jimmy-dexon): BlockConverter.Block() is called twice in this method.
if err := con.sanityCheck(blockConv); err != nil {
return err
}
b := blockConv.Block()
var (
deliveredBlocks []*types.Block
earlyDelivered bool
)
// To avoid application layer modify the content of block during
// processing, we should always operate based on the cloned one.
b = b.Clone()
con.lock.Lock()
defer con.lock.Unlock()
// Perform reliable broadcast checking.
if err = con.rbModule.processBlock(b); err != nil {
return err
}
for _, b := range con.rbModule.extractBlocks() {
// Notify application layer that some block is strongly acked.
con.app.StronglyAcked(b.Hash)
// Perform total ordering.
deliveredBlocks, earlyDelivered, err = con.toModule.processBlock(b)
if err != nil {
return
}
if len(deliveredBlocks) == 0 {
continue
}
for _, b := range deliveredBlocks {
if err = con.db.Put(*b); err != nil {
return
}
}
// TODO(mission): handle membership events here.
hashes := make(common.Hashes, len(deliveredBlocks))
for idx := range deliveredBlocks {
hashes[idx] = deliveredBlocks[idx].Hash
}
con.app.TotalOrderingDeliver(hashes, earlyDelivered)
// Perform timestamp generation.
deliveredBlocks, _, err = con.ctModule.processBlocks(
deliveredBlocks)
if err != nil {
return
}
for _, b := range deliveredBlocks {
if err = con.ccModule.processBlock(b); err != nil {
return
}
if err = con.db.Update(*b); err != nil {
return
}
con.app.DeliverBlock(b.Hash, b.Notary.Timestamp)
}
var notaryAck types.NotaryAck
notaryAck, err = con.ccModule.prepareNotaryAck(con.prvKey)
if err != nil {
return
}
con.app.NotaryAck(notaryAck)
}
return
}
func (con *Consensus) checkPrepareBlock(
b *types.Block, proposeTime time.Time) (err error) {
if (b.ProposerID == types.ValidatorID{}) {
err = &ErrMissingBlockInfo{MissingField: "ProposerID"}
return
}
return
}
// PrepareBlock would setup header fields of block based on its ProposerID.
func (con *Consensus) PrepareBlock(blockConv types.BlockConverter,
proposeTime time.Time) (err error) {
b := blockConv.Block()
if err = con.checkPrepareBlock(b, proposeTime); err != nil {
return
}
con.lock.RLock()
defer con.lock.RUnlock()
con.rbModule.prepareBlock(b)
b.Timestamps[b.ProposerID] = proposeTime
b.Hash, err = hashBlock(b)
if err != nil {
return
}
b.Signature, err = con.prvKey.Sign(b.Hash)
if err != nil {
return
}
blockConv.SetBlock(b)
return
}
// PrepareGenesisBlock would setup header fields for genesis block.
func (con *Consensus) PrepareGenesisBlock(blockConv types.BlockConverter,
proposeTime time.Time) (err error) {
b := blockConv.Block()
if err = con.checkPrepareBlock(b, proposeTime); err != nil {
return
}
if len(b.Payloads()) != 0 {
err = ErrGenesisBlockNotEmpty
return
}
b.Height = 0
b.ParentHash = common.Hash{}
b.Acks = make(map[common.Hash]struct{})
b.Timestamps = make(map[types.ValidatorID]time.Time)
for vID := range con.gov.GetValidatorSet() {
b.Timestamps[vID] = time.Time{}
}
b.Timestamps[b.ProposerID] = proposeTime
b.Hash, err = hashBlock(b)
if err != nil {
return
}
b.Signature, err = con.prvKey.Sign(b.Hash)
if err != nil {
return
}
blockConv.SetBlock(b)
return
}
// ProcessNotaryAck is the entry point to submit one notary ack.
func (con *Consensus) ProcessNotaryAck(notaryAck types.NotaryAck) (err error) {
err = con.ccModule.processNotaryAck(notaryAck)
return
}
// NotaryAcks returns the latest NotaryAck received from all other validators.
func (con *Consensus) NotaryAcks() (
notaryAcks map[types.ValidatorID]types.NotaryAck) {
notaryAcks = make(map[types.ValidatorID]types.NotaryAck)
for k, v := range con.ccModule.notaryAcks() {
notaryAcks[k] = v
}
return
}