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tendermint/evidence/pool.go

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package evidence
import (
"bytes"
"errors"
"fmt"
"reflect"
"sync"
"sync/atomic"
"time"
"github.com/gogo/protobuf/proto"
gogotypes "github.com/gogo/protobuf/types"
dbm "github.com/tendermint/tm-db"
abci "github.com/tendermint/tendermint/abci/types"
clist "github.com/tendermint/tendermint/libs/clist"
"github.com/tendermint/tendermint/libs/log"
evproto "github.com/tendermint/tendermint/proto/tendermint/evidence"
tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
sm "github.com/tendermint/tendermint/state"
"github.com/tendermint/tendermint/types"
)
const (
baseKeyCommitted = byte(0x00)
baseKeyPending = byte(0x01)
)
// Pool maintains a pool of valid evidence to be broadcasted and committed
type Pool struct {
logger log.Logger
evidenceStore dbm.DB
evidenceList *clist.CList // concurrent linked-list of evidence
evidenceSize uint32 // amount of pending evidence
// needed to load validators to verify evidence
stateDB sm.Store
// needed to load headers and commits to verify evidence
blockStore BlockStore
mtx sync.Mutex
// latest state
state sm.State
pruningHeight int64
pruningTime time.Time
}
// NewPool creates an evidence pool. If using an existing evidence store,
// it will add all pending evidence to the concurrent list.
func NewPool(evidenceDB dbm.DB, stateDB sm.Store, blockStore BlockStore) (*Pool, error) {
state, err := stateDB.Load()
if err != nil {
return nil, fmt.Errorf("cannot load state: %w", err)
}
pool := &Pool{
stateDB: stateDB,
blockStore: blockStore,
state: state,
logger: log.NewNopLogger(),
evidenceStore: evidenceDB,
evidenceList: clist.New(),
evidenceSize: 0,
pruningHeight: state.LastBlockHeight,
pruningTime: state.LastBlockTime,
}
// if pending evidence already in db, in event of prior failure, then check for expiration,
// update the size and load it back to the evidenceList
pool.removeExpiredPendingEvidence()
evList, err := pool.listEvidence(baseKeyPending, -1)
if err != nil {
return nil, err
}
atomic.AddUint32(&pool.evidenceSize, uint32(len(evList)))
for _, ev := range evList {
pool.evidenceList.PushBack(ev)
}
return pool, nil
}
// PendingEvidence is used primarily as part of block proposal and returns up to maxNum of uncommitted evidence.
func (evpool *Pool) PendingEvidence(maxNum uint32) []types.Evidence {
evidence, err := evpool.listEvidence(baseKeyPending, int64(maxNum))
if err != nil {
evpool.logger.Error("Unable to retrieve pending evidence", "err", err)
}
return evidence
}
// Update pulls the latest state to be used for expiration and evidence params and then prunes all expired evidence
func (evpool *Pool) Update(state sm.State) {
// sanity check
if state.LastBlockHeight <= evpool.state.LastBlockHeight {
panic(fmt.Sprintf(
"Failed EvidencePool.Update new state height is less than or equal to previous state height: %d <= %d",
state.LastBlockHeight,
evpool.state.LastBlockHeight,
))
}
evpool.logger.Info("Updating evidence pool", "last_block_height", state.LastBlockHeight,
"last_block_time", state.LastBlockTime)
// update the state
evpool.updateState(state)
// prune pending evidence when it has expired. This also updates when the next evidence will expire
if atomic.LoadUint32(&evpool.evidenceSize) > 0 && state.LastBlockHeight > evpool.pruningHeight &&
state.LastBlockTime.After(evpool.pruningTime) {
evpool.pruningHeight, evpool.pruningTime = evpool.removeExpiredPendingEvidence()
}
}
// AddEvidence checks the evidence is valid and adds it to the pool.
func (evpool *Pool) AddEvidence(ev types.Evidence) error {
evpool.logger.Debug("Attempting to add evidence", "ev", ev)
// We have already verified this piece of evidence - no need to do it again
if evpool.isPending(ev) {
return errors.New("evidence already verified and added")
}
// 1) Verify against state.
evInfo, err := evpool.verify(ev)
if err != nil {
return types.NewErrInvalidEvidence(ev, err)
}
// 2) Save to store.
if err := evpool.addPendingEvidence(evInfo); err != nil {
return fmt.Errorf("can't add evidence to pending list: %w", err)
}
// 3) Add evidence to clist.
evpool.evidenceList.PushBack(ev)
evpool.logger.Info("Verified new evidence of byzantine behavior", "evidence", ev)
return nil
}
// AddEvidenceFromConsensus should be exposed only to the consensus so it can add evidence to the pool
// directly without the need for verification.
func (evpool *Pool) AddEvidenceFromConsensus(ev types.Evidence, time time.Time, valSet *types.ValidatorSet) error {
var (
vals []*types.Validator
totalPower int64
)
if evpool.isPending(ev) {
return errors.New("evidence already verified and added") // we already have this evidence
}
switch ev := ev.(type) {
case *types.DuplicateVoteEvidence:
_, val := valSet.GetByAddress(ev.VoteA.ValidatorAddress)
vals = append(vals, val)
totalPower = valSet.TotalVotingPower()
default:
return fmt.Errorf("unrecognized evidence type: %T", ev)
}
evInfo := &info{
Evidence: ev,
Time: time,
Validators: vals,
TotalVotingPower: totalPower,
}
if err := evpool.addPendingEvidence(evInfo); err != nil {
return fmt.Errorf("can't add evidence to pending list: %w", err)
}
evpool.evidenceList.PushBack(ev)
evpool.logger.Info("Verified new evidence of byzantine behavior", "evidence", ev)
return nil
}
// CheckEvidence takes an array of evidence from a block and verifies all the evidence there.
// If it has already verified the evidence then it jumps to the next one. It ensures that no
// evidence has already been committed or is being proposed twice. It also adds any
// evidence that it doesn't currently have so that it can quickly form ABCI Evidence later.
func (evpool *Pool) CheckEvidence(evList types.EvidenceList) error {
hashes := make([][]byte, len(evList))
for idx, ev := range evList {
ok := evpool.fastCheck(ev)
if !ok {
evInfo, err := evpool.verify(ev)
if err != nil {
return &types.ErrInvalidEvidence{Evidence: ev, Reason: err}
}
if err := evpool.addPendingEvidence(evInfo); err != nil {
evpool.logger.Error("Can't add evidence to pending list", "err", err, "evInfo", evInfo)
}
evpool.logger.Info("Verified new evidence of byzantine behavior", "evidence", ev)
}
// check for duplicate evidence. We cache hashes so we don't have to work them out again.
hashes[idx] = ev.Hash()
for i := idx - 1; i >= 0; i-- {
if bytes.Equal(hashes[i], hashes[idx]) {
return &types.ErrInvalidEvidence{Evidence: ev, Reason: errors.New("duplicate evidence")}
}
}
}
return nil
}
// ABCIEvidence processes all the evidence in the block, marking it as committed and removing it
// from the pending database. It then forms the individual abci evidence that will be passed back to
// the application.
func (evpool *Pool) ABCIEvidence(height int64, evidence []types.Evidence) []abci.Evidence {
// make a map of committed evidence to remove from the clist
blockEvidenceMap := make(map[string]struct{}, len(evidence))
abciEvidence := make([]abci.Evidence, 0)
for _, ev := range evidence {
// get entire evidence info from pending list
infoBytes, err := evpool.evidenceStore.Get(keyPending(ev))
if err != nil {
evpool.logger.Error("Unable to retrieve evidence to pass to ABCI. "+
"Evidence pool should have seen this evidence before",
"evidence", ev, "err", err)
continue
}
var infoProto evproto.Info
err = infoProto.Unmarshal(infoBytes)
if err != nil {
evpool.logger.Error("Decoding evidence info failed", "err", err, "height", ev.Height(), "hash", ev.Hash())
continue
}
evInfo, err := infoFromProto(&infoProto)
if err != nil {
evpool.logger.Error("Converting evidence info from proto failed", "err", err, "height", ev.Height(),
"hash", ev.Hash())
continue
}
var evType abci.EvidenceType
switch ev.(type) {
case *types.DuplicateVoteEvidence:
evType = abci.EvidenceType_DUPLICATE_VOTE
case *types.LightClientAttackEvidence:
evType = abci.EvidenceType_LIGHT_CLIENT_ATTACK
default:
evpool.logger.Error("Unknown evidence type", "T", reflect.TypeOf(ev))
continue
}
for _, val := range evInfo.Validators {
abciEv := abci.Evidence{
Type: evType,
Validator: types.TM2PB.Validator(val),
Height: ev.Height(),
Time: evInfo.Time,
TotalVotingPower: evInfo.TotalVotingPower,
}
abciEvidence = append(abciEvidence, abciEv)
evpool.logger.Info("Created ABCI evidence", "ev", abciEv)
}
// we can now remove the evidence from the pending list and the clist that we use for gossiping
evpool.removePendingEvidence(ev)
blockEvidenceMap[evMapKey(ev)] = struct{}{}
// Add evidence to the committed list
// As the evidence is stored in the block store we only need to record the height that it was saved at.
key := keyCommitted(ev)
h := gogotypes.Int64Value{Value: height}
evBytes, err := proto.Marshal(&h)
if err != nil {
panic(err)
}
if err := evpool.evidenceStore.Set(key, evBytes); err != nil {
evpool.logger.Error("Unable to add committed evidence", "err", err)
}
}
// remove committed evidence from the clist
if len(blockEvidenceMap) != 0 {
evpool.removeEvidenceFromList(blockEvidenceMap)
}
return abciEvidence
}
// EvidenceFront goes to the first evidence in the clist
func (evpool *Pool) EvidenceFront() *clist.CElement {
return evpool.evidenceList.Front()
}
// EvidenceWaitChan is a channel that closes once the first evidence in the list is there. i.e Front is not nil
func (evpool *Pool) EvidenceWaitChan() <-chan struct{} {
return evpool.evidenceList.WaitChan()
}
// SetLogger sets the Logger.
func (evpool *Pool) SetLogger(l log.Logger) {
evpool.logger = l
}
// State returns the current state of the evpool.
func (evpool *Pool) State() sm.State {
evpool.mtx.Lock()
defer evpool.mtx.Unlock()
return evpool.state
}
//--------------------------------------------------------------------------
// Info is a wrapper around the evidence that the evidence pool receives with extensive
// information of what validators were malicious, the time of the attack and the total voting power
// This is saved as a form of cache so that the evidence pool can easily produce the ABCI Evidence
// needed to be sent to the application.
type info struct {
Evidence types.Evidence
Time time.Time
Validators []*types.Validator
TotalVotingPower int64
}
// ToProto encodes into protobuf
func (ei info) ToProto() (*evproto.Info, error) {
evpb, err := types.EvidenceToProto(ei.Evidence)
if err != nil {
return nil, err
}
valsProto := make([]*tmproto.Validator, len(ei.Validators))
for i := 0; i < len(ei.Validators); i++ {
valp, err := ei.Validators[i].ToProto()
if err != nil {
return nil, err
}
valsProto[i] = valp
}
return &evproto.Info{
Evidence: *evpb,
Time: ei.Time,
Validators: valsProto,
TotalVotingPower: ei.TotalVotingPower,
}, nil
}
// InfoFromProto decodes from protobuf into Info
func infoFromProto(proto *evproto.Info) (info, error) {
if proto == nil {
return info{}, errors.New("nil evidence info")
}
ev, err := types.EvidenceFromProto(&proto.Evidence)
if err != nil {
return info{}, err
}
vals := make([]*types.Validator, len(proto.Validators))
for i := 0; i < len(proto.Validators); i++ {
val, err := types.ValidatorFromProto(proto.Validators[i])
if err != nil {
return info{}, err
}
vals[i] = val
}
return info{
Evidence: ev,
Time: proto.Time,
Validators: vals,
TotalVotingPower: proto.TotalVotingPower,
}, nil
}
//--------------------------------------------------------------------------
// fastCheck leverages the fact that the evidence pool may have already verified the evidence to see if it can
// quickly conclude that the evidence is already valid.
func (evpool *Pool) fastCheck(ev types.Evidence) bool {
key := keyPending(ev)
if lcae, ok := ev.(*types.LightClientAttackEvidence); ok {
evBytes, err := evpool.evidenceStore.Get(key)
if evBytes == nil { // the evidence is not in the nodes pending list
return false
}
if err != nil {
evpool.logger.Error("Failed to load evidence", "err", err, "evidence", lcae)
return false
}
evInfo, err := bytesToInfo(evBytes)
if err != nil {
evpool.logger.Error("Failed to convert evidence from proto", "err", err, "evidence", lcae)
return false
}
// ensure that all the validators that the evidence pool have found to be malicious
// are present in the list of commit signatures in the conflicting block
OUTER:
for _, sig := range lcae.ConflictingBlock.Commit.Signatures {
for _, val := range evInfo.Validators {
if bytes.Equal(val.Address, sig.ValidatorAddress) {
continue OUTER
}
}
// a validator we know is malicious is not included in the commit
evpool.logger.Info("Fast check failed: a validator we know is malicious is not " +
"in the commit sigs. Reverting to full verification")
return false
}
return true
}
// for all other evidence the evidence pool just checks if it is already in the pending db
return evpool.isPending(ev)
}
// IsExpired checks whether evidence or a polc is expired by checking whether a height and time is older
// than set by the evidence consensus parameters
func (evpool *Pool) isExpired(height int64, time time.Time) bool {
var (
params = evpool.State().ConsensusParams.Evidence
ageDuration = evpool.State().LastBlockTime.Sub(time)
ageNumBlocks = evpool.State().LastBlockHeight - height
)
return ageNumBlocks > params.MaxAgeNumBlocks &&
ageDuration > params.MaxAgeDuration
}
// IsCommitted returns true if we have already seen this exact evidence and it is already marked as committed.
func (evpool *Pool) isCommitted(evidence types.Evidence) bool {
key := keyCommitted(evidence)
ok, err := evpool.evidenceStore.Has(key)
if err != nil {
evpool.logger.Error("Unable to find committed evidence", "err", err)
}
return ok
}
// IsPending checks whether the evidence is already pending. DB errors are passed to the logger.
func (evpool *Pool) isPending(evidence types.Evidence) bool {
key := keyPending(evidence)
ok, err := evpool.evidenceStore.Has(key)
if err != nil {
evpool.logger.Error("Unable to find pending evidence", "err", err)
}
return ok
}
func (evpool *Pool) addPendingEvidence(evInfo *info) error {
evpb, err := evInfo.ToProto()
if err != nil {
return fmt.Errorf("unable to convert to proto, err: %w", err)
}
evBytes, err := evpb.Marshal()
if err != nil {
return fmt.Errorf("unable to marshal evidence: %w", err)
}
key := keyPending(evInfo.Evidence)
err = evpool.evidenceStore.Set(key, evBytes)
if err != nil {
return fmt.Errorf("can't persist evidence: %w", err)
}
atomic.AddUint32(&evpool.evidenceSize, 1)
return nil
}
func (evpool *Pool) removePendingEvidence(evidence types.Evidence) {
key := keyPending(evidence)
if err := evpool.evidenceStore.Delete(key); err != nil {
evpool.logger.Error("Unable to delete pending evidence", "err", err)
} else {
atomic.AddUint32(&evpool.evidenceSize, ^uint32(0))
evpool.logger.Info("Deleted pending evidence", "evidence", evidence)
}
}
// listEvidence lists up to maxNum pieces of evidence for the given prefix key.
// If maxNum is -1, there's no cap on the size of returned evidence.
func (evpool *Pool) listEvidence(prefixKey byte, maxNum int64) ([]types.Evidence, error) {
var count int64
var evidence []types.Evidence
iter, err := dbm.IteratePrefix(evpool.evidenceStore, []byte{prefixKey})
if err != nil {
return nil, fmt.Errorf("database error: %v", err)
}
defer iter.Close()
for ; iter.Valid(); iter.Next() {
if count == maxNum {
return evidence, nil
}
count++
evInfo, err := bytesToInfo(iter.Value())
if err != nil {
return nil, err
}
evidence = append(evidence, evInfo.Evidence)
}
return evidence, nil
}
func (evpool *Pool) removeExpiredPendingEvidence() (int64, time.Time) {
iter, err := dbm.IteratePrefix(evpool.evidenceStore, []byte{baseKeyPending})
if err != nil {
evpool.logger.Error("Unable to iterate over pending evidence", "err", err)
return evpool.State().LastBlockHeight, evpool.State().LastBlockTime
}
defer iter.Close()
blockEvidenceMap := make(map[string]struct{})
for ; iter.Valid(); iter.Next() {
evInfo, err := bytesToInfo(iter.Value())
if err != nil {
evpool.logger.Error("Error in transition evidence from protobuf", "err", err)
continue
}
if !evpool.isExpired(evInfo.Evidence.Height(), evInfo.Time) {
if len(blockEvidenceMap) != 0 {
evpool.removeEvidenceFromList(blockEvidenceMap)
}
// return the time with which this evidence will have expired so we know when to prune next
return evInfo.Evidence.Height() + evpool.State().ConsensusParams.Evidence.MaxAgeNumBlocks + 1,
evInfo.Time.Add(evpool.State().ConsensusParams.Evidence.MaxAgeDuration).Add(time.Second)
}
evpool.removePendingEvidence(evInfo.Evidence)
blockEvidenceMap[evMapKey(evInfo.Evidence)] = struct{}{}
}
// We either have no pending evidence or all evidence has expired
if len(blockEvidenceMap) != 0 {
evpool.removeEvidenceFromList(blockEvidenceMap)
}
return evpool.State().LastBlockHeight, evpool.State().LastBlockTime
}
func (evpool *Pool) removeEvidenceFromList(
blockEvidenceMap map[string]struct{}) {
for e := evpool.evidenceList.Front(); e != nil; e = e.Next() {
// Remove from clist
ev := e.Value.(types.Evidence)
if _, ok := blockEvidenceMap[evMapKey(ev)]; ok {
evpool.evidenceList.Remove(e)
e.DetachPrev()
}
}
}
func (evpool *Pool) updateState(state sm.State) {
evpool.mtx.Lock()
defer evpool.mtx.Unlock()
evpool.state = state
}
func bytesToInfo(evBytes []byte) (info, error) {
var evpb evproto.Info
err := evpb.Unmarshal(evBytes)
if err != nil {
return info{}, err
}
return infoFromProto(&evpb)
}
func evMapKey(ev types.Evidence) string {
return string(ev.Hash())
}
// big endian padded hex
func bE(h int64) string {
return fmt.Sprintf("%0.16X", h)
}
func keyCommitted(evidence types.Evidence) []byte {
return append([]byte{baseKeyCommitted}, keySuffix(evidence)...)
}
func keyPending(evidence types.Evidence) []byte {
return append([]byte{baseKeyPending}, keySuffix(evidence)...)
}
func keySuffix(evidence types.Evidence) []byte {
return []byte(fmt.Sprintf("%s/%X", bE(evidence.Height()), evidence.Hash()))
}