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// 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 (
"errors"
"fmt"
"math/rand"
"os"
"sort"
"time"
"github.com/dexon-foundation/dexon-consensus/common"
"github.com/dexon-foundation/dexon-consensus/core/crypto"
"github.com/dexon-foundation/dexon-consensus/core/types"
"github.com/dexon-foundation/dexon-consensus/core/utils"
)
// NodeSetCache is type alias to avoid fullnode compile error when moving
// it to core/utils package.
type NodeSetCache = utils.NodeSetCache
// NewNodeSetCache is function alias to avoid fullnode compile error when moving
// it to core/utils package.
var NewNodeSetCache = utils.NewNodeSetCache
var (
debug = false
// ErrEmptyTimestamps would be reported if Block.timestamps is empty.
ErrEmptyTimestamps = errors.New("timestamp vector should not be empty")
)
func init() {
if os.Getenv("DEBUG") != "" {
debug = true
}
}
// Debugf is like fmt.Printf, but only output when we are in debug mode.
func Debugf(format string, args ...interface{}) {
if debug {
fmt.Printf(format, args...)
}
}
// Debugln is like fmt.Println, but only output when we are in debug mode.
func Debugln(args ...interface{}) {
if debug {
fmt.Println(args...)
}
}
func interpoTime(t1 time.Time, t2 time.Time, sep int) []time.Time {
if sep == 0 {
return []time.Time{}
}
if t1.After(t2) {
return interpoTime(t2, t1, sep)
}
timestamps := make([]time.Time, sep)
duration := t2.Sub(t1)
period := time.Duration(
(duration.Nanoseconds() / int64(sep+1))) * time.Nanosecond
prevTime := t1
for idx := range timestamps {
prevTime = prevTime.Add(period)
timestamps[idx] = prevTime
}
return timestamps
}
func getMedianTime(timestamps []time.Time) (t time.Time, err error) {
if len(timestamps) == 0 {
err = ErrEmptyTimestamps
return
}
tscopy := make([]time.Time, 0, len(timestamps))
for _, ts := range timestamps {
tscopy = append(tscopy, ts)
}
sort.Sort(common.ByTime(tscopy))
if len(tscopy)%2 == 0 {
t1 := tscopy[len(tscopy)/2-1]
t2 := tscopy[len(tscopy)/2]
t = interpoTime(t1, t2, 1)[0]
} else {
t = tscopy[len(tscopy)/2]
}
return
}
func removeFromSortedUint32Slice(xs []uint32, x uint32) []uint32 {
indexToRemove := sort.Search(len(xs), func(idx int) bool {
return xs[idx] >= x
})
if indexToRemove == len(xs) || xs[indexToRemove] != x {
// This value is not found.
return xs
}
return append(xs[:indexToRemove], xs[indexToRemove+1:]...)
}
// pickBiasedTime returns a biased time based on a given range.
func pickBiasedTime(base time.Time, biasedRange time.Duration) time.Time {
return base.Add(time.Duration(rand.Intn(int(biasedRange))))
}
// HashConfigurationBlock returns the hash value of configuration block.
func HashConfigurationBlock(
notarySet map[types.NodeID]struct{},
config *types.Config,
snapshotHash common.Hash,
prevHash common.Hash,
) common.Hash {
notaryIDs := make(types.NodeIDs, 0, len(notarySet))
for nID := range notarySet {
notaryIDs = append(notaryIDs, nID)
}
sort.Sort(notaryIDs)
notarySetBytes := make([]byte, 0, len(notarySet)*len(common.Hash{}))
for _, nID := range notaryIDs {
notarySetBytes = append(notarySetBytes, nID.Hash[:]...)
}
configBytes := config.Bytes()
return crypto.Keccak256Hash(
notarySetBytes[:],
configBytes[:],
snapshotHash[:],
prevHash[:],
)
}
// VerifyBlock verifies the signature of types.Block.
func VerifyBlock(b *types.Block) (err error) {
hash, err := hashBlock(b)
if err != nil {
return
}
if hash != b.Hash {
err = ErrIncorrectHash
return
}
pubKey, err := crypto.SigToPub(b.Hash, b.Signature)
if err != nil {
return
}
if !b.ProposerID.Equal(types.NewNodeID(pubKey)) {
err = ErrIncorrectSignature
return
}
return
}
// VerifyAgreementResult perform sanity check against a types.AgreementResult
// instance.
func VerifyAgreementResult(
res *types.AgreementResult, cache *utils.NodeSetCache) error {
notarySet, err := cache.GetNotarySet(
res.Position.Round, res.Position.ChainID)
if err != nil {
return err
}
if len(res.Votes) < len(notarySet)/3*2+1 {
return ErrNotEnoughVotes
}
if len(res.Votes) > len(notarySet) {
return ErrIncorrectVoteProposer
}
for _, vote := range res.Votes {
if res.IsEmptyBlock {
if (vote.BlockHash != common.Hash{}) {
return ErrIncorrectVoteBlockHash
}
} else {
if vote.BlockHash != res.BlockHash {
return ErrIncorrectVoteBlockHash
}
}
if vote.Type != types.VoteCom {
return ErrIncorrectVoteType
}
if vote.Position != res.Position {
return ErrIncorrectVotePosition
}
if _, exist := notarySet[vote.ProposerID]; !exist {
return ErrIncorrectVoteProposer
}
ok, err := verifyVoteSignature(&vote)
if err != nil {
return err
}
if !ok {
return ErrIncorrectVoteSignature
}
}
return nil
}
// DiffUint64 calculates difference between two uint64.
func DiffUint64(a, b uint64) uint64 {
if a > b {
return a - b
}
return b - a
}
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