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package types
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import (
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"bytes"
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"encoding/binary"
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"errors"
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"fmt"
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"strings"
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"time"
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"github.com/tendermint/tendermint/crypto/merkle"
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"github.com/tendermint/tendermint/crypto/tmhash"
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tmjson "github.com/tendermint/tendermint/libs/json"
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tmrand "github.com/tendermint/tendermint/libs/rand"
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tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
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)
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// Evidence represents any provable malicious activity by a validator.
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// Verification logic for each evidence is part of the evidence module.
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type Evidence interface {
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Height() int64 // height of the infraction
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Bytes() []byte // bytes which comprise the evidence
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Hash() []byte // hash of the evidence
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ValidateBasic() error // basic consistency check
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String() string // string format of the evidence
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}
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//--------------------------------------------------------------------------------------
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// DuplicateVoteEvidence contains evidence a validator signed two conflicting
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// votes.
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type DuplicateVoteEvidence struct {
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VoteA *Vote `json:"vote_a"`
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VoteB *Vote `json:"vote_b"`
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}
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var _ Evidence = &DuplicateVoteEvidence{}
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// NewDuplicateVoteEvidence creates DuplicateVoteEvidence with right ordering given
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// two conflicting votes. If one of the votes is nil, evidence returned is nil as well
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func NewDuplicateVoteEvidence(vote1, vote2 *Vote) *DuplicateVoteEvidence {
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var voteA, voteB *Vote
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if vote1 == nil || vote2 == nil {
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return nil
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}
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if strings.Compare(vote1.BlockID.Key(), vote2.BlockID.Key()) == -1 {
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voteA = vote1
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voteB = vote2
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} else {
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voteA = vote2
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voteB = vote1
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}
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return &DuplicateVoteEvidence{
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VoteA: voteA,
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VoteB: voteB,
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}
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}
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// String returns a string representation of the evidence.
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func (dve *DuplicateVoteEvidence) String() string {
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return fmt.Sprintf("DuplicateVoteEvidence{VoteA: %v, VoteB: %v}", dve.VoteA, dve.VoteB)
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}
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// Height returns the height this evidence refers to.
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func (dve *DuplicateVoteEvidence) Height() int64 {
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return dve.VoteA.Height
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}
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// Bytes returns the proto-encoded evidence as a byte array.
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func (dve *DuplicateVoteEvidence) Bytes() []byte {
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pbe := dve.ToProto()
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bz, err := pbe.Marshal()
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if err != nil {
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panic(err)
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}
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return bz
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}
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// Hash returns the hash of the evidence.
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func (dve *DuplicateVoteEvidence) Hash() []byte {
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return tmhash.Sum(dve.Bytes())
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}
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// ValidateBasic performs basic validation.
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func (dve *DuplicateVoteEvidence) ValidateBasic() error {
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if dve == nil {
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return errors.New("empty duplicate vote evidence")
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}
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if dve.VoteA == nil || dve.VoteB == nil {
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return fmt.Errorf("one or both of the votes are empty %v, %v", dve.VoteA, dve.VoteB)
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}
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if err := dve.VoteA.ValidateBasic(); err != nil {
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return fmt.Errorf("invalid VoteA: %w", err)
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}
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if err := dve.VoteB.ValidateBasic(); err != nil {
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return fmt.Errorf("invalid VoteB: %w", err)
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}
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// Enforce Votes are lexicographically sorted on blockID
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if strings.Compare(dve.VoteA.BlockID.Key(), dve.VoteB.BlockID.Key()) >= 0 {
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return errors.New("duplicate votes in invalid order")
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}
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return nil
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}
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// ToProto encodes DuplicateVoteEvidence to protobuf
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func (dve *DuplicateVoteEvidence) ToProto() *tmproto.DuplicateVoteEvidence {
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voteB := dve.VoteB.ToProto()
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voteA := dve.VoteA.ToProto()
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tp := tmproto.DuplicateVoteEvidence{
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VoteA: voteA,
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VoteB: voteB,
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}
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return &tp
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}
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// DuplicateVoteEvidenceFromProto decodes protobuf into DuplicateVoteEvidence
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func DuplicateVoteEvidenceFromProto(pb *tmproto.DuplicateVoteEvidence) (*DuplicateVoteEvidence, error) {
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if pb == nil {
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return nil, errors.New("nil duplicate vote evidence")
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}
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vA, err := VoteFromProto(pb.VoteA)
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if err != nil {
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return nil, err
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}
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vB, err := VoteFromProto(pb.VoteB)
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if err != nil {
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return nil, err
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}
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dve := NewDuplicateVoteEvidence(vA, vB)
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return dve, dve.ValidateBasic()
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}
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//------------------------------------ LIGHT EVIDENCE --------------------------------------
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// LightClientAttackEvidence is a generalized evidence that captures all forms of known attacks on
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// a light client such that a full node can verify, propose and commit the evidence on-chain for
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// punishment of the malicious validators. There are three forms of attacks: Lunatic, Equivocation
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// and Amnesia. These attacks are exhaustive. You can find a more detailed overview of this at
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// tendermint/docs/architecture/adr-047-handling-evidence-from-light-client.md
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type LightClientAttackEvidence struct {
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ConflictingBlock *LightBlock
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CommonHeight int64
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}
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var _ Evidence = &LightClientAttackEvidence{}
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// Height returns the last height at which the primary provider and witness provider had the same header.
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// We use this as the height of the infraction rather than the actual conflicting header because we know
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// that the malicious validators were bonded at this height which is important for evidence expiry
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func (l *LightClientAttackEvidence) Height() int64 {
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return l.CommonHeight
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}
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// Bytes returns the proto-encoded evidence as a byte array
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func (l *LightClientAttackEvidence) Bytes() []byte {
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pbe, err := l.ToProto()
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if err != nil {
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panic(err)
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}
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bz, err := pbe.Marshal()
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if err != nil {
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panic(err)
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}
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return bz
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}
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// Hash returns the hash of the header and the commonHeight. This is designed to cause hash collisions with evidence
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// that have the same conflicting header and common height but different permutations of validator commit signatures.
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// The reason for this is that we don't want to allow several permutations of the same evidence to be committed on
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// chain. Ideally we commit the header with the most commit signatures but anything greater than 1/3 is sufficient.
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func (l *LightClientAttackEvidence) Hash() []byte {
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buf := make([]byte, binary.MaxVarintLen64)
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n := binary.PutVarint(buf, l.CommonHeight)
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bz := make([]byte, tmhash.Size+n)
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copy(bz[:tmhash.Size-1], l.ConflictingBlock.Hash().Bytes())
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copy(bz[tmhash.Size:], buf)
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return tmhash.Sum(bz)
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}
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// ValidateBasic performs basic validation such that the evidence is consistent and can now be used for verification.
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func (l *LightClientAttackEvidence) ValidateBasic() error {
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if l.ConflictingBlock == nil {
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return errors.New("conflicting block is nil")
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}
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// this check needs to be done before we can run validate basic
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if l.ConflictingBlock.Header == nil {
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return errors.New("conflicting block missing header")
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}
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if err := l.ConflictingBlock.ValidateBasic(l.ConflictingBlock.ChainID); err != nil {
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return fmt.Errorf("invalid conflicting light block: %w", err)
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}
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if l.CommonHeight <= 0 {
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return errors.New("negative or zero common height")
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}
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// check that common height isn't ahead of the height of the conflicting block. It
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// is possible that they are the same height if the light node witnesses either an
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// amnesia or a equivocation attack.
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if l.CommonHeight > l.ConflictingBlock.Height {
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return fmt.Errorf("common height is ahead of the conflicting block height (%d > %d)",
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l.CommonHeight, l.ConflictingBlock.Height)
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}
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return nil
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}
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// String returns a string representation of LightClientAttackEvidence
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func (l *LightClientAttackEvidence) String() string {
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return fmt.Sprintf("LightClientAttackEvidence{ConflictingBlock: %v, CommonHeight: %d}",
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l.ConflictingBlock.String(), l.CommonHeight)
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}
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// ToProto encodes LightClientAttackEvidence to protobuf
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func (l *LightClientAttackEvidence) ToProto() (*tmproto.LightClientAttackEvidence, error) {
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conflictingBlock, err := l.ConflictingBlock.ToProto()
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if err != nil {
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return nil, err
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}
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return &tmproto.LightClientAttackEvidence{
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ConflictingBlock: conflictingBlock,
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CommonHeight: l.CommonHeight,
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}, nil
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}
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// LightClientAttackEvidenceFromProto decodes protobuf
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func LightClientAttackEvidenceFromProto(l *tmproto.LightClientAttackEvidence) (*LightClientAttackEvidence, error) {
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if l == nil {
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return nil, errors.New("empty light client attack evidence")
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}
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conflictingBlock, err := LightBlockFromProto(l.ConflictingBlock)
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if err != nil {
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return nil, err
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}
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le := &LightClientAttackEvidence{
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ConflictingBlock: conflictingBlock,
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CommonHeight: l.CommonHeight,
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}
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return le, le.ValidateBasic()
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}
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//------------------------------------------------------------------------------------------
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// EvidenceList is a list of Evidence. Evidences is not a word.
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type EvidenceList []Evidence
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// Hash returns the simple merkle root hash of the EvidenceList.
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func (evl EvidenceList) Hash() []byte {
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// These allocations are required because Evidence is not of type Bytes, and
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// golang slices can't be typed cast. This shouldn't be a performance problem since
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// the Evidence size is capped.
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evidenceBzs := make([][]byte, len(evl))
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for i := 0; i < len(evl); i++ {
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evidenceBzs[i] = evl[i].Bytes()
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}
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return merkle.HashFromByteSlices(evidenceBzs)
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}
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func (evl EvidenceList) String() string {
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s := ""
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for _, e := range evl {
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s += fmt.Sprintf("%s\t\t", e)
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}
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return s
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}
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// Has returns true if the evidence is in the EvidenceList.
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func (evl EvidenceList) Has(evidence Evidence) bool {
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for _, ev := range evl {
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if bytes.Equal(evidence.Hash(), ev.Hash()) {
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return true
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}
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}
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return false
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}
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//------------------------------------------ PROTO --------------------------------------
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// EvidenceToProto is a generalized function for encoding evidence that conforms to the
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// evidence interface to protobuf
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func EvidenceToProto(evidence Evidence) (*tmproto.Evidence, error) {
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if evidence == nil {
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return nil, errors.New("nil evidence")
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}
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switch evi := evidence.(type) {
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case *DuplicateVoteEvidence:
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pbev := evi.ToProto()
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return &tmproto.Evidence{
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Sum: &tmproto.Evidence_DuplicateVoteEvidence{
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DuplicateVoteEvidence: pbev,
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},
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}, nil
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case *LightClientAttackEvidence:
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pbev, err := evi.ToProto()
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if err != nil {
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return nil, err
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}
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return &tmproto.Evidence{
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Sum: &tmproto.Evidence_LightClientAttackEvidence{
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LightClientAttackEvidence: pbev,
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},
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}, nil
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default:
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return nil, fmt.Errorf("toproto: evidence is not recognized: %T", evi)
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}
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}
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// EvidenceFromProto is a generalized function for decoding protobuf into the
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// evidence interface
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func EvidenceFromProto(evidence *tmproto.Evidence) (Evidence, error) {
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if evidence == nil {
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return nil, errors.New("nil evidence")
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}
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switch evi := evidence.Sum.(type) {
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case *tmproto.Evidence_DuplicateVoteEvidence:
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return DuplicateVoteEvidenceFromProto(evi.DuplicateVoteEvidence)
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case *tmproto.Evidence_LightClientAttackEvidence:
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return LightClientAttackEvidenceFromProto(evi.LightClientAttackEvidence)
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default:
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return nil, errors.New("evidence is not recognized")
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}
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}
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func init() {
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tmjson.RegisterType(&DuplicateVoteEvidence{}, "tendermint/DuplicateVoteEvidence")
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tmjson.RegisterType(&LightClientAttackEvidence{}, "tendermint/LightClientAttackEvidence")
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}
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//-------------------------------------------- ERRORS --------------------------------------
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// ErrInvalidEvidence wraps a piece of evidence and the error denoting how or why it is invalid.
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type ErrInvalidEvidence struct {
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Evidence Evidence
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Reason error
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}
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// NewErrInvalidEvidence returns a new EvidenceInvalid with the given err.
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func NewErrInvalidEvidence(ev Evidence, err error) *ErrInvalidEvidence {
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return &ErrInvalidEvidence{ev, err}
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}
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// Error returns a string representation of the error.
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func (err *ErrInvalidEvidence) Error() string {
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return fmt.Sprintf("Invalid evidence: %v. Evidence: %v", err.Reason, err.Evidence)
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}
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// ErrEvidenceOverflow is for when there the amount of evidence exceeds the max bytes.
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type ErrEvidenceOverflow struct {
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Max int64
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Got int64
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}
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// NewErrEvidenceOverflow returns a new ErrEvidenceOverflow where got > max.
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func NewErrEvidenceOverflow(max, got int64) *ErrEvidenceOverflow {
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return &ErrEvidenceOverflow{max, got}
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}
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// Error returns a string representation of the error.
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func (err *ErrEvidenceOverflow) Error() string {
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return fmt.Sprintf("Too much evidence: Max %d, got %d", err.Max, err.Got)
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}
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//-------------------------------------------- MOCKING --------------------------------------
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// unstable - use only for testing
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// assumes the round to be 0 and the validator index to be 0
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func NewMockDuplicateVoteEvidence(height int64, time time.Time, chainID string) *DuplicateVoteEvidence {
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val := NewMockPV()
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return NewMockDuplicateVoteEvidenceWithValidator(height, time, val, chainID)
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}
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func NewMockDuplicateVoteEvidenceWithValidator(height int64, time time.Time,
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pv PrivValidator, chainID string) *DuplicateVoteEvidence {
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pubKey, _ := pv.GetPubKey()
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voteA := makeMockVote(height, 0, 0, pubKey.Address(), randBlockID(), time)
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vA := voteA.ToProto()
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_ = pv.SignVote(chainID, vA)
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voteA.Signature = vA.Signature
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voteB := makeMockVote(height, 0, 0, pubKey.Address(), randBlockID(), time)
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vB := voteB.ToProto()
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_ = pv.SignVote(chainID, vB)
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voteB.Signature = vB.Signature
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return NewDuplicateVoteEvidence(voteA, voteB)
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}
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func makeMockVote(height int64, round, index int32, addr Address,
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blockID BlockID, time time.Time) *Vote {
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return &Vote{
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Type: tmproto.SignedMsgType(2),
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Height: height,
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Round: round,
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BlockID: blockID,
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Timestamp: time,
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ValidatorAddress: addr,
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ValidatorIndex: index,
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}
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}
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func randBlockID() BlockID {
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return BlockID{
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Hash: tmrand.Bytes(tmhash.Size),
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PartSetHeader: PartSetHeader{
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Total: 1,
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Hash: tmrand.Bytes(tmhash.Size),
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},
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}
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}
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