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package types
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"strings"
"time"
"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 {
Height() int64 // height of the infraction
Bytes() []byte // bytes which comprise the evidence
Hash() []byte // hash of the evidence
ValidateBasic() error // basic consistency check
String() string // string format of the evidence
}
//--------------------------------------------------------------------------------------
// DuplicateVoteEvidence contains evidence a validator signed two conflicting
// votes.
type DuplicateVoteEvidence struct {
VoteA *Vote `json:"vote_a"`
VoteB *Vote `json:"vote_b"`
}
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) *DuplicateVoteEvidence {
var voteA, voteB *Vote
if vote1 == nil || vote2 == nil {
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,
}
}
// 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)
}
// Height returns the height this evidence refers to.
func (dve *DuplicateVoteEvidence) Height() int64 {
return dve.VoteA.Height
}
// 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())
}
// 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,
}
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 := NewDuplicateVoteEvidence(vA, vB)
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
}
var _ Evidence = &LightClientAttackEvidence{}
// 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
}
// 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
}
// 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 but anything greater than 1/3 is sufficient.
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)
}
// 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 err := l.ConflictingBlock.ValidateBasic(l.ConflictingBlock.ChainID); err != nil {
return fmt.Errorf("invalid conflicting light block: %w", err)
}
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)
}
return nil
}
// String returns a string representation of LightClientAttackEvidence
func (l *LightClientAttackEvidence) String() string {
return fmt.Sprintf("LightClientAttackEvidence{ConflictingBlock: %v, CommonHeight: %d}",
l.ConflictingBlock.String(), l.CommonHeight)
}
// ToProto encodes LightClientAttackEvidence to protobuf
func (l *LightClientAttackEvidence) ToProto() (*tmproto.LightClientAttackEvidence, error) {
conflictingBlock, err := l.ConflictingBlock.ToProto()
if err != nil {
return nil, err
}
return &tmproto.LightClientAttackEvidence{
ConflictingBlock: conflictingBlock,
CommonHeight: l.CommonHeight,
}, nil
}
// LightClientAttackEvidenceFromProto decodes protobuf
func LightClientAttackEvidenceFromProto(l *tmproto.LightClientAttackEvidence) (*LightClientAttackEvidence, error) {
if l == nil {
return nil, errors.New("empty light client attack evidence")
}
conflictingBlock, err := LightBlockFromProto(l.ConflictingBlock)
if err != nil {
return nil, err
}
le := &LightClientAttackEvidence{
ConflictingBlock: conflictingBlock,
CommonHeight: l.CommonHeight,
}
return le, le.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++ {
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)
}
func NewMockDuplicateVoteEvidenceWithValidator(height int64, time time.Time,
pv PrivValidator, chainID string) *DuplicateVoteEvidence {
pubKey, _ := pv.GetPubKey()
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)
}
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),
},
}
}