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package evidence
import (
"fmt"
"sync"
"time"
dbm "github.com/tendermint/tm-db"
clist "github.com/tendermint/tendermint/libs/clist"
"github.com/tendermint/tendermint/libs/log"
sm "github.com/tendermint/tendermint/state"
"github.com/tendermint/tendermint/store"
"github.com/tendermint/tendermint/types"
)
const (
baseKeyCommitted = byte(0x00)
baseKeyPending = byte(0x01)
baseKeyPOLC = byte(0x02)
)
// 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
// needed to load validators to verify evidence
stateDB dbm.DB
// needed to load headers to verify evidence
blockStore *store.BlockStore
mtx sync.Mutex
// latest state
state sm.State
// a map of active validators and respective last heights validator is active
// if it was in validator set after EvidenceParams.MaxAgeNumBlocks or
// currently is (ie. [MaxAgeNumBlocks, CurrentHeight])
// In simple words, it means it's still bonded -> therefore slashable.
valToLastHeight valToLastHeightMap
}
// Validator.Address -> Last height it was in validator set
type valToLastHeightMap map[string]int64
func NewPool(stateDB, evidenceDB dbm.DB, blockStore *store.BlockStore) (*Pool, error) {
var (
state = sm.LoadState(stateDB)
)
valToLastHeight, err := buildValToLastHeightMap(state, stateDB, blockStore)
if err != nil {
return nil, err
}
pool := &Pool{
stateDB: stateDB,
blockStore: blockStore,
state: state,
logger: log.NewNopLogger(),
evidenceStore: evidenceDB,
evidenceList: clist.New(),
valToLastHeight: valToLastHeight,
}
// if pending evidence already in db, in event of prior failure, then load it back to the evidenceList
evList := pool.AllPendingEvidence()
for _, ev := range evList {
if pool.IsEvidenceExpired(ev) {
pool.removePendingEvidence(ev)
continue
}
pool.evidenceList.PushBack(ev)
}
return pool, nil
}
// PendingEvidence is used primarily as part of block proposal and returns up to maxNum of uncommitted evidence.
// If maxNum is -1, all evidence is returned. Pending evidence is prioritised based on time.
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
}
func (evpool *Pool) AllPendingEvidence() []types.Evidence {
evidence, err := evpool.listEvidence(baseKeyPending, -1)
if err != nil {
evpool.logger.Error("Unable to retrieve pending evidence", "err", err)
}
return evidence
}
// Update uses the latest block & state to update its copy of the state,
// validator to last height map and calls MarkEvidenceAsCommitted.
func (evpool *Pool) Update(block *types.Block, state sm.State) {
// sanity check
if state.LastBlockHeight != block.Height {
panic(
fmt.Sprintf("Failed EvidencePool.Update sanity check: got state.Height=%d with block.Height=%d",
state.LastBlockHeight,
block.Height,
),
)
}
// remove evidence from pending and mark committed
evpool.MarkEvidenceAsCommitted(block.Height, block.Time, block.Evidence.Evidence)
// remove expired evidence - this should be done at every height to ensure we don't send expired evidence to peers
evpool.removeExpiredPendingEvidence()
// as it's not vital to remove expired POLCs, we only prune periodically
if block.Height%state.ConsensusParams.Evidence.MaxAgeNumBlocks == 0 {
evpool.pruneExpiredPOLC()
}
// update the state
evpool.mtx.Lock()
defer evpool.mtx.Unlock()
evpool.state = state
evpool.updateValToLastHeight(block.Height, state)
}
// AddPOLC adds a proof of lock change to the evidence database
// that may be needed in the future to verify votes
func (evpool *Pool) AddPOLC(polc types.ProofOfLockChange) error {
key := keyPOLC(polc)
polcBytes := cdc.MustMarshalBinaryBare(polc)
return evpool.evidenceStore.Set(key, polcBytes)
}
// AddEvidence checks the evidence is valid and adds it to the pool. If
// evidence is composite (ConflictingHeadersEvidence), it will be broken up
// into smaller pieces.
func (evpool *Pool) AddEvidence(evidence types.Evidence) error {
var (
state = evpool.State()
evList = []types.Evidence{evidence}
)
valSet, err := sm.LoadValidators(evpool.stateDB, evidence.Height())
if err != nil {
return fmt.Errorf("can't load validators at height #%d: %w", evidence.Height(), err)
}
// Break composite evidence into smaller pieces.
if ce, ok := evidence.(types.CompositeEvidence); ok {
evpool.logger.Info("Breaking up composite evidence", "ev", evidence)
blockMeta := evpool.blockStore.LoadBlockMeta(evidence.Height())
if blockMeta == nil {
return fmt.Errorf("don't have block meta at height #%d", evidence.Height())
}
if err := ce.VerifyComposite(&blockMeta.Header, valSet); err != nil {
return err
}
// XXX: Copy here since this should be a rare case.
evpool.mtx.Lock()
valToLastHeightCopy := make(valToLastHeightMap, len(evpool.valToLastHeight))
for k, v := range evpool.valToLastHeight {
valToLastHeightCopy[k] = v
}
evpool.mtx.Unlock()
evList = ce.Split(&blockMeta.Header, valSet, valToLastHeightCopy)
}
for _, ev := range evList {
if evpool.Has(ev) {
continue
}
// For lunatic validator evidence, a header needs to be fetched.
var header *types.Header
if _, ok := ev.(*types.LunaticValidatorEvidence); ok {
header = evpool.Header(ev.Height())
if header == nil {
return fmt.Errorf("don't have block meta at height #%d", ev.Height())
}
}
// 1) Verify against state.
if err := sm.VerifyEvidence(evpool.stateDB, state, ev, header); err != nil {
return fmt.Errorf("failed to verify %v: %w", ev, err)
}
// 2) Save to store.
if err := evpool.addPendingEvidence(ev); err != nil {
return fmt.Errorf("database error: %v", err)
}
// 3) Add evidence to clist.
evpool.evidenceList.PushBack(ev)
evpool.logger.Info("Verified new evidence of byzantine behaviour", "evidence", ev)
}
return nil
}
// MarkEvidenceAsCommitted marks all the evidence as committed and removes it
// from the queue.
func (evpool *Pool) MarkEvidenceAsCommitted(height int64, lastBlockTime time.Time, evidence []types.Evidence) {
// make a map of committed evidence to remove from the clist
blockEvidenceMap := make(map[string]struct{})
for _, ev := range evidence {
// As the evidence is stored in the block store we only need to record the height that it was saved at.
key := keyCommitted(ev)
evBytes := cdc.MustMarshalBinaryBare(height)
if err := evpool.evidenceStore.Set(key, evBytes); err != nil {
evpool.logger.Error("Unable to add committed evidence", "err", err)
// if we can't move evidence to committed then don't remove the evidence from pending
continue
}
// if pending, remove from that bucket, remember not all evidence has been seen before
if evpool.IsPending(ev) {
evpool.removePendingEvidence(ev)
blockEvidenceMap[evMapKey(ev)] = struct{}{}
}
}
// remove committed evidence from the clist
if len(blockEvidenceMap) != 0 {
evpool.removeEvidenceFromList(blockEvidenceMap)
}
}
// Has checks whether the evidence exists either pending or already committed
func (evpool *Pool) Has(evidence types.Evidence) bool {
return evpool.IsPending(evidence) || evpool.IsCommitted(evidence)
}
// IsEvidenceExpired checks whether evidence is past the maximum age where it can be used
func (evpool *Pool) IsEvidenceExpired(evidence types.Evidence) bool {
return evpool.IsExpired(evidence.Height(), evidence.Time())
}
// 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
}
// RetrievePOLC attempts to find a polc at the given height and round, if not there it returns an error
func (evpool *Pool) RetrievePOLC(height int64, round int) (types.ProofOfLockChange, error) {
var polc types.ProofOfLockChange
key := keyPOLCFromHeightAndRound(height, round)
polcBytes, err := evpool.evidenceStore.Get(key)
if err != nil {
return polc, err
}
if polcBytes == nil {
return polc, fmt.Errorf("unable to find polc at height %d and round %d", height, round)
}
err = cdc.UnmarshalBinaryBare(polcBytes, &polc)
return polc, err
}
// 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
}
// Header gets the header from the block store at a specified height.
// Is used for validation of LunaticValidatorEvidence
func (evpool *Pool) Header(height int64) *types.Header {
blockMeta := evpool.blockStore.LoadBlockMeta(height)
if blockMeta == nil {
return nil
}
return &blockMeta.Header
}
// ValidatorLastHeight returns the last height of the validator w/ the
// given address. 0 - if address never was a validator or was such a
// long time ago (> ConsensusParams.Evidence.MaxAgeDuration && >
// ConsensusParams.Evidence.MaxAgeNumBlocks).
func (evpool *Pool) ValidatorLastHeight(address []byte) int64 {
evpool.mtx.Lock()
defer evpool.mtx.Unlock()
h, ok := evpool.valToLastHeight[string(address)]
if !ok {
return 0
}
return h
}
// State returns the current state of the evpool.
func (evpool *Pool) State() sm.State {
evpool.mtx.Lock()
defer evpool.mtx.Unlock()
return evpool.state
}
func (evpool *Pool) addPendingEvidence(evidence types.Evidence) error {
evBytes := cdc.MustMarshalBinaryBare(evidence)
key := keyPending(evidence)
return evpool.evidenceStore.Set(key, evBytes)
}
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 {
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() {
val := iter.Value()
if count == maxNum {
return evidence, nil
}
count++
var ev types.Evidence
err := cdc.UnmarshalBinaryBare(val, &ev)
if err != nil {
return nil, err
}
evidence = append(evidence, ev)
}
return evidence, nil
}
func (evpool *Pool) removeExpiredPendingEvidence() {
iter, err := dbm.IteratePrefix(evpool.evidenceStore, []byte{baseKeyPending})
if err != nil {
evpool.logger.Error("Unable to iterate over pending evidence", "err", err)
return
}
defer iter.Close()
blockEvidenceMap := make(map[string]struct{})
for ; iter.Valid(); iter.Next() {
evBytes := iter.Value()
var ev types.Evidence
err := cdc.UnmarshalBinaryBare(evBytes, &ev)
if err != nil {
evpool.logger.Error("Unable to unmarshal POLC", "err", err)
continue
}
if !evpool.IsExpired(ev.Height()-1, ev.Time()) {
if len(blockEvidenceMap) != 0 {
evpool.removeEvidenceFromList(blockEvidenceMap)
}
return
}
evpool.removePendingEvidence(ev)
blockEvidenceMap[evMapKey(ev)] = struct{}{}
}
}
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) pruneExpiredPOLC() {
evpool.logger.Debug("Pruning expired POLC's")
iter, err := dbm.IteratePrefix(evpool.evidenceStore, []byte{baseKeyPOLC})
if err != nil {
evpool.logger.Error("Unable to iterate over POLC's", "err", err)
return
}
defer iter.Close()
for ; iter.Valid(); iter.Next() {
proofBytes := iter.Value()
var proof types.ProofOfLockChange
err := cdc.UnmarshalBinaryBare(proofBytes, &proof)
if err != nil {
evpool.logger.Error("Unable to unmarshal POLC", "err", err)
continue
}
if !evpool.IsExpired(proof.Height()-1, proof.Time()) {
return
}
err = evpool.evidenceStore.Delete(iter.Key())
if err != nil {
evpool.logger.Error("Unable to delete expired POLC", "err", err)
continue
}
evpool.logger.Info("Deleted expired POLC", "polc", proof)
}
}
func evMapKey(ev types.Evidence) string {
return string(ev.Hash())
}
func (evpool *Pool) updateValToLastHeight(blockHeight int64, state sm.State) {
// Update current validators & add new ones.
for _, val := range state.Validators.Validators {
evpool.valToLastHeight[string(val.Address)] = blockHeight
}
// Remove validators outside of MaxAgeNumBlocks & MaxAgeDuration.
removeHeight := blockHeight - state.ConsensusParams.Evidence.MaxAgeNumBlocks
if removeHeight >= 1 {
for val, height := range evpool.valToLastHeight {
if height <= removeHeight {
delete(evpool.valToLastHeight, val)
}
}
}
}
func buildValToLastHeightMap(state sm.State, stateDB dbm.DB, blockStore *store.BlockStore) (valToLastHeightMap, error) {
var (
valToLastHeight = make(map[string]int64)
params = state.ConsensusParams.Evidence
numBlocks = int64(0)
minAgeTime = time.Now().Add(-params.MaxAgeDuration)
height = state.LastBlockHeight
)
if height == 0 {
return valToLastHeight, nil
}
meta := blockStore.LoadBlockMeta(height)
if meta == nil {
return nil, fmt.Errorf("block meta for height %d not found", height)
}
blockTime := meta.Header.Time
// From state.LastBlockHeight, build a map of "active" validators until
// MaxAgeNumBlocks is passed and block time is less than now() -
// MaxAgeDuration.
for height >= 1 && (numBlocks <= params.MaxAgeNumBlocks || !blockTime.Before(minAgeTime)) {
valSet, err := sm.LoadValidators(stateDB, height)
if err != nil {
// last stored height -> return
if _, ok := err.(sm.ErrNoValSetForHeight); ok {
return valToLastHeight, nil
}
return nil, fmt.Errorf("validator set for height %d not found", height)
}
for _, val := range valSet.Validators {
key := string(val.Address)
if _, ok := valToLastHeight[key]; !ok {
valToLastHeight[key] = height
}
}
height--
if height > 0 {
// NOTE: we assume here blockStore and state.Validators are in sync. I.e if
// block N is stored, then validators for height N are also stored in
// state.
meta := blockStore.LoadBlockMeta(height)
if meta == nil {
return nil, fmt.Errorf("block meta for height %d not found", height)
}
blockTime = meta.Header.Time
}
numBlocks++
}
return valToLastHeight, nil
}
// 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 keyPOLC(polc types.ProofOfLockChange) []byte {
return keyPOLCFromHeightAndRound(polc.Height(), polc.Round())
}
func keyPOLCFromHeightAndRound(height int64, round int) []byte {
return append([]byte{baseKeyPOLC}, []byte(fmt.Sprintf("%s/%s", bE(height), bE(int64(round))))...)
}
func keySuffix(evidence types.Evidence) []byte {
return []byte(fmt.Sprintf("%s/%X", bE(evidence.Height()), evidence.Hash()))
}
// ErrInvalidEvidence returns when evidence failed to validate
type ErrInvalidEvidence struct {
Reason error
}
func (e ErrInvalidEvidence) Error() string {
return fmt.Sprintf("evidence is not valid: %v ", e.Reason)
}