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package evidence
import (
"errors"
"fmt"
"sync"
"time"
"github.com/gogo/protobuf/proto"
gogotypes "github.com/gogo/protobuf/types"
dbm "github.com/tendermint/tm-db"
clist "github.com/tendermint/tendermint/libs/clist"
"github.com/tendermint/tendermint/libs/log"
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
// needed to load validators to verify evidence
stateDB StateStore
// needed to load headers to verify evidence
blockStore BlockStore
mtx sync.Mutex
// latest state
state sm.State
}
// 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 StateStore, blockStore BlockStore) (*Pool, error) {
var (
state = stateDB.LoadState()
)
pool := &Pool{
stateDB: stateDB,
blockStore: blockStore,
state: state,
logger: log.NewNopLogger(),
evidenceStore: evidenceDB,
evidenceList: clist.New(),
}
// 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 {
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 prioritized based on time.
func (evpool *Pool) PendingEvidence(maxNum uint32) []types.Evidence {
evpool.removeExpiredPendingEvidence()
evidence, err := evpool.listEvidence(baseKeyPending, int64(maxNum))
if err != nil {
evpool.logger.Error("Unable to retrieve pending evidence", "err", err)
}
return evidence
}
// AllPendingEvidence returns all evidence ready to be proposed and committed.
func (evpool *Pool) AllPendingEvidence() []types.Evidence {
evpool.removeExpiredPendingEvidence()
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 any evidence that has been committed, to prune all expired evidence
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,
),
)
}
// update the state
evpool.updateState(state)
// remove evidence from pending and mark committed
evpool.MarkEvidenceAsCommitted(block.Height, block.Evidence.Evidence)
// prune pending, committed and potential evidence and polc's periodically
if block.Height%state.ConsensusParams.Evidence.MaxAgeNumBlocks == 0 {
evpool.logger.Debug("Pruning expired evidence")
// NOTE: As this is periodic, this implies that there may be some pending evidence in the
// db that have already expired. However, expired evidence will also be removed whenever
// PendingEvidence() is called ensuring that no expired evidence is proposed.
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)
if evpool.Has(ev) {
return nil
}
// 1) Verify against state.
if err := evpool.verify(ev); err != nil {
return types.NewErrEvidenceInvalid(ev, err)
}
// 2) Save to store.
if err := evpool.addPendingEvidence(ev); err != nil {
return fmt.Errorf("database error when adding evidence: %v", err)
}
// 3) Add evidence to clist.
evpool.evidenceList.PushBack(ev)
evpool.logger.Info("Verified new evidence of byzantine behavior", "evidence", ev)
return nil
}
// Verify verifies the evidence against the node's (or evidence pool's) state. More specifically, to validate
// evidence against state is to validate it against the nodes own header and validator set for that height. This ensures
// as well as meeting the evidence's own validation rules, that the evidence hasn't expired, that the validator is still
// bonded and that the evidence can be committed to the chain.
func (evpool *Pool) Verify(evidence types.Evidence) error {
if evpool.IsCommitted(evidence) {
return errors.New("evidence was already committed")
}
// We have already verified this piece of evidence - no need to do it again
if evpool.IsPending(evidence) {
return nil
}
return evpool.verify(evidence)
}
func (evpool *Pool) verify(evidence types.Evidence) error {
return VerifyEvidence(evidence, evpool.State(), evpool.stateDB, evpool.blockStore)
}
// MarkEvidenceAsCommitted marks all the evidence as committed and removes it
// from the queue.
func (evpool *Pool) MarkEvidenceAsCommitted(height int64, 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)
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)
// 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
}
// 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
}
func (evpool *Pool) addPendingEvidence(evidence types.Evidence) error {
evi, err := types.EvidenceToProto(evidence)
if err != nil {
return fmt.Errorf("unable to convert to proto, err: %w", err)
}
evBytes, err := proto.Marshal(evi)
if err != nil {
return fmt.Errorf("unable to marshal evidence: %w", err)
}
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() {
if count == maxNum {
return evidence, nil
}
count++
val := iter.Value()
var (
ev types.Evidence
evpb tmproto.Evidence
)
err := proto.Unmarshal(val, &evpb)
if err != nil {
return nil, err
}
ev, err = types.EvidenceFromProto(&evpb)
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
evpb tmproto.Evidence
)
err := proto.Unmarshal(evBytes, &evpb)
if err != nil {
evpool.logger.Error("Unable to unmarshal Evidence", "err", err)
continue
}
ev, err = types.EvidenceFromProto(&evpb)
if err != nil {
evpool.logger.Error("Error in transition evidence from protobuf", "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) updateState(state sm.State) {
evpool.mtx.Lock()
defer evpool.mtx.Unlock()
evpool.state = state
}
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()))
}