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tendermint/types/evidence.go

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package types
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"sort"
"strings"
"time"
abci "github.com/tendermint/tendermint/abci/types"
"github.com/tendermint/tendermint/crypto/merkle"
"github.com/tendermint/tendermint/crypto/tmhash"
tmjson "github.com/tendermint/tendermint/libs/json"
tmrand "github.com/tendermint/tendermint/libs/rand"
tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
)
// Evidence represents any provable malicious activity by a validator.
// Verification logic for each evidence is part of the evidence module.
type Evidence interface {
ABCI() []abci.Evidence // forms individual evidence to be sent to the application
Bytes() []byte // bytes which comprise the evidence
Hash() []byte // hash of the evidence
Height() int64 // height of the infraction
String() string // string format of the evidence
Time() time.Time // time of the infraction
ValidateBasic() error // basic consistency check
}
//--------------------------------------------------------------------------------------
// DuplicateVoteEvidence contains evidence of a single validator signing two conflicting votes.
type DuplicateVoteEvidence struct {
VoteA *Vote `json:"vote_a"`
VoteB *Vote `json:"vote_b"`
// abci specific information
TotalVotingPower int64
ValidatorPower int64
Timestamp time.Time
}
var _ Evidence = &DuplicateVoteEvidence{}
// NewDuplicateVoteEvidence creates DuplicateVoteEvidence with right ordering given
// two conflicting votes. If one of the votes is nil, evidence returned is nil as well
func NewDuplicateVoteEvidence(vote1, vote2 *Vote, blockTime time.Time, valSet *ValidatorSet) *DuplicateVoteEvidence {
var voteA, voteB *Vote
if vote1 == nil || vote2 == nil || valSet == nil {
return nil
}
idx, val := valSet.GetByAddress(vote1.ValidatorAddress)
if idx == -1 {
return nil
}
if strings.Compare(vote1.BlockID.Key(), vote2.BlockID.Key()) == -1 {
voteA = vote1
voteB = vote2
} else {
voteA = vote2
voteB = vote1
}
return &DuplicateVoteEvidence{
VoteA: voteA,
VoteB: voteB,
TotalVotingPower: valSet.TotalVotingPower(),
ValidatorPower: val.VotingPower,
Timestamp: blockTime,
}
}
// ABCI returns the application relevant representation of the evidence
func (dve *DuplicateVoteEvidence) ABCI() []abci.Evidence {
return []abci.Evidence{{
Type: abci.EvidenceType_DUPLICATE_VOTE,
Validator: abci.Validator{
Address: dve.VoteA.ValidatorAddress,
Power: dve.ValidatorPower,
},
Height: dve.VoteA.Height,
Time: dve.Timestamp,
TotalVotingPower: dve.TotalVotingPower,
}}
}
// Bytes returns the proto-encoded evidence as a byte array.
func (dve *DuplicateVoteEvidence) Bytes() []byte {
pbe := dve.ToProto()
bz, err := pbe.Marshal()
if err != nil {
panic(err)
}
return bz
}
// Hash returns the hash of the evidence.
func (dve *DuplicateVoteEvidence) Hash() []byte {
return tmhash.Sum(dve.Bytes())
}
// Height returns the height of the infraction
func (dve *DuplicateVoteEvidence) Height() int64 {
return dve.VoteA.Height
}
// String returns a string representation of the evidence.
func (dve *DuplicateVoteEvidence) String() string {
return fmt.Sprintf("DuplicateVoteEvidence{VoteA: %v, VoteB: %v}", dve.VoteA, dve.VoteB)
}
// Time returns the time of the infraction
func (dve *DuplicateVoteEvidence) Time() time.Time {
return dve.Timestamp
}
// ValidateBasic performs basic validation.
func (dve *DuplicateVoteEvidence) ValidateBasic() error {
if dve == nil {
return errors.New("empty duplicate vote evidence")
}
if dve.VoteA == nil || dve.VoteB == nil {
return fmt.Errorf("one or both of the votes are empty %v, %v", dve.VoteA, dve.VoteB)
}
if err := dve.VoteA.ValidateBasic(); err != nil {
return fmt.Errorf("invalid VoteA: %w", err)
}
if err := dve.VoteB.ValidateBasic(); err != nil {
return fmt.Errorf("invalid VoteB: %w", err)
}
// Enforce Votes are lexicographically sorted on blockID
if strings.Compare(dve.VoteA.BlockID.Key(), dve.VoteB.BlockID.Key()) >= 0 {
return errors.New("duplicate votes in invalid order")
}
return nil
}
// ToProto encodes DuplicateVoteEvidence to protobuf
func (dve *DuplicateVoteEvidence) ToProto() *tmproto.DuplicateVoteEvidence {
voteB := dve.VoteB.ToProto()
voteA := dve.VoteA.ToProto()
tp := tmproto.DuplicateVoteEvidence{
VoteA: voteA,
VoteB: voteB,
TotalVotingPower: dve.TotalVotingPower,
ValidatorPower: dve.ValidatorPower,
Timestamp: dve.Timestamp,
}
return &tp
}
// DuplicateVoteEvidenceFromProto decodes protobuf into DuplicateVoteEvidence
func DuplicateVoteEvidenceFromProto(pb *tmproto.DuplicateVoteEvidence) (*DuplicateVoteEvidence, error) {
if pb == nil {
return nil, errors.New("nil duplicate vote evidence")
}
vA, err := VoteFromProto(pb.VoteA)
if err != nil {
return nil, err
}
vB, err := VoteFromProto(pb.VoteB)
if err != nil {
return nil, err
}
dve := &DuplicateVoteEvidence{
VoteA: vA,
VoteB: vB,
TotalVotingPower: pb.TotalVotingPower,
ValidatorPower: pb.ValidatorPower,
Timestamp: pb.Timestamp,
}
return dve, dve.ValidateBasic()
}
//------------------------------------ LIGHT EVIDENCE --------------------------------------
// LightClientAttackEvidence is a generalized evidence that captures all forms of known attacks on
// a light client such that a full node can verify, propose and commit the evidence on-chain for
// punishment of the malicious validators. There are three forms of attacks: Lunatic, Equivocation
// and Amnesia. These attacks are exhaustive. You can find a more detailed overview of this at
// tendermint/docs/architecture/adr-047-handling-evidence-from-light-client.md
type LightClientAttackEvidence struct {
ConflictingBlock *LightBlock
CommonHeight int64
// abci specific information
ByzantineValidators []*Validator // validators in the validator set that misbehaved in creating the conflicting block
TotalVotingPower int64 // total voting power of the validator set at the common height
Timestamp time.Time // timestamp of the block at the common height
}
var _ Evidence = &LightClientAttackEvidence{}
// ABCI forms an array of abci evidence for each byzantine validator
func (l *LightClientAttackEvidence) ABCI() []abci.Evidence {
abciEv := make([]abci.Evidence, len(l.ByzantineValidators))
for idx, val := range l.ByzantineValidators {
abciEv[idx] = abci.Evidence{
Type: abci.EvidenceType_LIGHT_CLIENT_ATTACK,
Validator: TM2PB.Validator(val),
Height: l.Height(),
Time: l.Timestamp,
TotalVotingPower: l.TotalVotingPower,
}
}
return abciEv
}
// Bytes returns the proto-encoded evidence as a byte array
func (l *LightClientAttackEvidence) Bytes() []byte {
pbe, err := l.ToProto()
if err != nil {
panic(err)
}
bz, err := pbe.Marshal()
if err != nil {
panic(err)
}
return bz
}
// GetByzantineValidators finds out what style of attack LightClientAttackEvidence was and then works out who
// the malicious validators were and returns them. This is used both for forming the ByzantineValidators
// field and for validating that it is correct. Validators are ordered based on validator power
func (l *LightClientAttackEvidence) GetByzantineValidators(commonVals *ValidatorSet,
trusted *SignedHeader) []*Validator {
var validators []*Validator
// First check if the header is invalid. This means that it is a lunatic attack and therefore we take the
// validators who are in the commonVals and voted for the lunatic header
if l.ConflictingHeaderIsInvalid(trusted.Header) {
for _, commitSig := range l.ConflictingBlock.Commit.Signatures {
if !commitSig.ForBlock() {
continue
}
_, val := commonVals.GetByAddress(commitSig.ValidatorAddress)
if val == nil {
// validator wasn't in the common validator set
continue
}
validators = append(validators, val)
}
sort.Sort(ValidatorsByVotingPower(validators))
return validators
} else if trusted.Commit.Round == l.ConflictingBlock.Commit.Round {
// This is an equivocation attack as both commits are in the same round. We then find the validators
// from the conflicting light block validator set that voted in both headers.
// Validator hashes are the same therefore the indexing order of validators are the same and thus we
// only need a single loop to find the validators that voted twice.
for i := 0; i < len(l.ConflictingBlock.Commit.Signatures); i++ {
sigA := l.ConflictingBlock.Commit.Signatures[i]
if sigA.Absent() {
continue
}
sigB := trusted.Commit.Signatures[i]
if sigB.Absent() {
continue
}
_, val := l.ConflictingBlock.ValidatorSet.GetByAddress(sigA.ValidatorAddress)
validators = append(validators, val)
}
sort.Sort(ValidatorsByVotingPower(validators))
return validators
}
// if the rounds are different then this is an amnesia attack. Unfortunately, given the nature of the attack,
// we aren't able yet to deduce which are malicious validators and which are not hence we return an
// empty validator set.
return validators
}
// ConflictingHeaderIsInvalid takes a trusted header and matches it againt a conflicting header
// to determine whether the conflicting header was the product of a valid state transition
// or not. If it is then all the deterministic fields of the header should be the same.
// If not, it is an invalid header and constitutes a lunatic attack.
func (l *LightClientAttackEvidence) ConflictingHeaderIsInvalid(trustedHeader *Header) bool {
return !bytes.Equal(trustedHeader.ValidatorsHash, l.ConflictingBlock.ValidatorsHash) ||
!bytes.Equal(trustedHeader.NextValidatorsHash, l.ConflictingBlock.NextValidatorsHash) ||
!bytes.Equal(trustedHeader.ConsensusHash, l.ConflictingBlock.ConsensusHash) ||
!bytes.Equal(trustedHeader.AppHash, l.ConflictingBlock.AppHash) ||
!bytes.Equal(trustedHeader.LastResultsHash, l.ConflictingBlock.LastResultsHash)
}
// Hash returns the hash of the header and the commonHeight. This is designed to cause hash collisions
// with evidence that have the same conflicting header and common height but different permutations
// of validator commit signatures. The reason for this is that we don't want to allow several
// permutations of the same evidence to be committed on chain. Ideally we commit the header with the
// most commit signatures (captures the most byzantine validators) but anything greater than 1/3 is
// sufficient.
// TODO: We should change the hash to include the commit, header, total voting power, byzantine
// validators and timestamp
func (l *LightClientAttackEvidence) Hash() []byte {
buf := make([]byte, binary.MaxVarintLen64)
n := binary.PutVarint(buf, l.CommonHeight)
bz := make([]byte, tmhash.Size+n)
copy(bz[:tmhash.Size-1], l.ConflictingBlock.Hash().Bytes())
copy(bz[tmhash.Size:], buf)
return tmhash.Sum(bz)
}
// Height returns the last height at which the primary provider and witness provider had the same header.
// We use this as the height of the infraction rather than the actual conflicting header because we know
// that the malicious validators were bonded at this height which is important for evidence expiry
func (l *LightClientAttackEvidence) Height() int64 {
return l.CommonHeight
}
// String returns a string representation of LightClientAttackEvidence
func (l *LightClientAttackEvidence) String() string {
return fmt.Sprintf(`LightClientAttackEvidence{
ConflictingBlock: %v,
CommonHeight: %d,
ByzatineValidators: %v,
TotalVotingPower: %d,
Timestamp: %v}#%X`,
l.ConflictingBlock.String(), l.CommonHeight, l.ByzantineValidators,
l.TotalVotingPower, l.Timestamp, l.Hash())
}
// Time returns the time of the common block where the infraction leveraged off.
func (l *LightClientAttackEvidence) Time() time.Time {
return l.Timestamp
}
// ValidateBasic performs basic validation such that the evidence is consistent and can now be used for verification.
func (l *LightClientAttackEvidence) ValidateBasic() error {
if l.ConflictingBlock == nil {
return errors.New("conflicting block is nil")
}
// this check needs to be done before we can run validate basic
if l.ConflictingBlock.Header == nil {
return errors.New("conflicting block missing header")
}
if l.TotalVotingPower <= 0 {
return errors.New("negative or zero total voting power")
}
if l.CommonHeight <= 0 {
return errors.New("negative or zero common height")
}
// check that common height isn't ahead of the height of the conflicting block. It
// is possible that they are the same height if the light node witnesses either an
// amnesia or a equivocation attack.
if l.CommonHeight > l.ConflictingBlock.Height {
return fmt.Errorf("common height is ahead of the conflicting block height (%d > %d)",
l.CommonHeight, l.ConflictingBlock.Height)
}
if err := l.ConflictingBlock.ValidateBasic(l.ConflictingBlock.ChainID); err != nil {
return fmt.Errorf("invalid conflicting light block: %w", err)
}
return nil
}
// ToProto encodes LightClientAttackEvidence to protobuf
func (l *LightClientAttackEvidence) ToProto() (*tmproto.LightClientAttackEvidence, error) {
conflictingBlock, err := l.ConflictingBlock.ToProto()
if err != nil {
return nil, err
}
byzVals := make([]*tmproto.Validator, len(l.ByzantineValidators))
for idx, val := range l.ByzantineValidators {
valpb, err := val.ToProto()
if err != nil {
return nil, err
}
byzVals[idx] = valpb
}
return &tmproto.LightClientAttackEvidence{
ConflictingBlock: conflictingBlock,
CommonHeight: l.CommonHeight,
ByzantineValidators: byzVals,
TotalVotingPower: l.TotalVotingPower,
Timestamp: l.Timestamp,
}, nil
}
// LightClientAttackEvidenceFromProto decodes protobuf
func LightClientAttackEvidenceFromProto(lpb *tmproto.LightClientAttackEvidence) (*LightClientAttackEvidence, error) {
if lpb == nil {
return nil, errors.New("empty light client attack evidence")
}
conflictingBlock, err := LightBlockFromProto(lpb.ConflictingBlock)
if err != nil {
return nil, err
}
byzVals := make([]*Validator, len(lpb.ByzantineValidators))
for idx, valpb := range lpb.ByzantineValidators {
val, err := ValidatorFromProto(valpb)
if err != nil {
return nil, err
}
byzVals[idx] = val
}
l := &LightClientAttackEvidence{
ConflictingBlock: conflictingBlock,
CommonHeight: lpb.CommonHeight,
ByzantineValidators: byzVals,
TotalVotingPower: lpb.TotalVotingPower,
Timestamp: lpb.Timestamp,
}
return l, l.ValidateBasic()
}
//------------------------------------------------------------------------------------------
// EvidenceList is a list of Evidence. Evidences is not a word.
type EvidenceList []Evidence
// Hash returns the simple merkle root hash of the EvidenceList.
func (evl EvidenceList) Hash() []byte {
// These allocations are required because Evidence is not of type Bytes, and
// golang slices can't be typed cast. This shouldn't be a performance problem since
// the Evidence size is capped.
evidenceBzs := make([][]byte, len(evl))
for i := 0; i < len(evl); i++ {
// TODO: We should change this to the hash. Using bytes contains some unexported data that
// may cause different hashes
evidenceBzs[i] = evl[i].Bytes()
}
return merkle.HashFromByteSlices(evidenceBzs)
}
func (evl EvidenceList) String() string {
s := ""
for _, e := range evl {
s += fmt.Sprintf("%s\t\t", e)
}
return s
}
// Has returns true if the evidence is in the EvidenceList.
func (evl EvidenceList) Has(evidence Evidence) bool {
for _, ev := range evl {
if bytes.Equal(evidence.Hash(), ev.Hash()) {
return true
}
}
return false
}
//------------------------------------------ PROTO --------------------------------------
// EvidenceToProto is a generalized function for encoding evidence that conforms to the
// evidence interface to protobuf
func EvidenceToProto(evidence Evidence) (*tmproto.Evidence, error) {
if evidence == nil {
return nil, errors.New("nil evidence")
}
switch evi := evidence.(type) {
case *DuplicateVoteEvidence:
pbev := evi.ToProto()
return &tmproto.Evidence{
Sum: &tmproto.Evidence_DuplicateVoteEvidence{
DuplicateVoteEvidence: pbev,
},
}, nil
case *LightClientAttackEvidence:
pbev, err := evi.ToProto()
if err != nil {
return nil, err
}
return &tmproto.Evidence{
Sum: &tmproto.Evidence_LightClientAttackEvidence{
LightClientAttackEvidence: pbev,
},
}, nil
default:
return nil, fmt.Errorf("toproto: evidence is not recognized: %T", evi)
}
}
// EvidenceFromProto is a generalized function for decoding protobuf into the
// evidence interface
func EvidenceFromProto(evidence *tmproto.Evidence) (Evidence, error) {
if evidence == nil {
return nil, errors.New("nil evidence")
}
switch evi := evidence.Sum.(type) {
case *tmproto.Evidence_DuplicateVoteEvidence:
return DuplicateVoteEvidenceFromProto(evi.DuplicateVoteEvidence)
case *tmproto.Evidence_LightClientAttackEvidence:
return LightClientAttackEvidenceFromProto(evi.LightClientAttackEvidence)
default:
return nil, errors.New("evidence is not recognized")
}
}
func init() {
tmjson.RegisterType(&DuplicateVoteEvidence{}, "tendermint/DuplicateVoteEvidence")
tmjson.RegisterType(&LightClientAttackEvidence{}, "tendermint/LightClientAttackEvidence")
}
//-------------------------------------------- ERRORS --------------------------------------
// ErrInvalidEvidence wraps a piece of evidence and the error denoting how or why it is invalid.
type ErrInvalidEvidence struct {
Evidence Evidence
Reason error
}
// NewErrInvalidEvidence returns a new EvidenceInvalid with the given err.
func NewErrInvalidEvidence(ev Evidence, err error) *ErrInvalidEvidence {
return &ErrInvalidEvidence{ev, err}
}
// Error returns a string representation of the error.
func (err *ErrInvalidEvidence) Error() string {
return fmt.Sprintf("Invalid evidence: %v. Evidence: %v", err.Reason, err.Evidence)
}
// ErrEvidenceOverflow is for when there the amount of evidence exceeds the max bytes.
type ErrEvidenceOverflow struct {
Max int64
Got int64
}
// NewErrEvidenceOverflow returns a new ErrEvidenceOverflow where got > max.
func NewErrEvidenceOverflow(max, got int64) *ErrEvidenceOverflow {
return &ErrEvidenceOverflow{max, got}
}
// Error returns a string representation of the error.
func (err *ErrEvidenceOverflow) Error() string {
return fmt.Sprintf("Too much evidence: Max %d, got %d", err.Max, err.Got)
}
//-------------------------------------------- MOCKING --------------------------------------
// unstable - use only for testing
// assumes the round to be 0 and the validator index to be 0
func NewMockDuplicateVoteEvidence(height int64, time time.Time, chainID string) *DuplicateVoteEvidence {
val := NewMockPV()
return NewMockDuplicateVoteEvidenceWithValidator(height, time, val, chainID)
}
// assumes voting power to be 10 and validator to be the only one in the set
func NewMockDuplicateVoteEvidenceWithValidator(height int64, time time.Time,
pv PrivValidator, chainID string) *DuplicateVoteEvidence {
pubKey, _ := pv.GetPubKey()
val := NewValidator(pubKey, 10)
voteA := makeMockVote(height, 0, 0, pubKey.Address(), randBlockID(), time)
vA := voteA.ToProto()
_ = pv.SignVote(chainID, vA)
voteA.Signature = vA.Signature
voteB := makeMockVote(height, 0, 0, pubKey.Address(), randBlockID(), time)
vB := voteB.ToProto()
_ = pv.SignVote(chainID, vB)
voteB.Signature = vB.Signature
return NewDuplicateVoteEvidence(voteA, voteB, time, NewValidatorSet([]*Validator{val}))
}
func makeMockVote(height int64, round, index int32, addr Address,
blockID BlockID, time time.Time) *Vote {
return &Vote{
Type: tmproto.SignedMsgType(2),
Height: height,
Round: round,
BlockID: blockID,
Timestamp: time,
ValidatorAddress: addr,
ValidatorIndex: index,
}
}
func randBlockID() BlockID {
return BlockID{
Hash: tmrand.Bytes(tmhash.Size),
PartSetHeader: PartSetHeader{
Total: 1,
Hash: tmrand.Bytes(tmhash.Size),
},
}
}