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package types
import (
"bytes"
"fmt"
"github.com/tendermint/go-crypto"
"github.com/tendermint/tmlibs/merkle"
)
// ErrEvidenceInvalid wraps a piece of evidence and the error denoting how or why it is invalid.
type ErrEvidenceInvalid struct {
Evidence Evidence
ErrorValue error
}
func NewEvidenceInvalidErr(ev Evidence, err error) *ErrEvidenceInvalid {
return &ErrEvidenceInvalid{ev, err}
}
// Error returns a string representation of the error.
func (err *ErrEvidenceInvalid) Error() string {
return fmt.Sprintf("Invalid evidence: %v. Evidence: %v", err.ErrorValue, err.Evidence)
}
//-------------------------------------------
// Evidence represents any provable malicious activity by a validator
type Evidence interface {
Address() []byte
Hash() []byte
Verify(chainID string) error
String() string
}
//-------------------------------------------
type Evidences []Evidence
func (evs Evidences) Hash() []byte {
// Recursive impl.
// Copied from tmlibs/merkle to avoid allocations
switch len(evs) {
case 0:
return nil
case 1:
return evs[0].Hash()
default:
left := Evidences(evs[:(len(evs)+1)/2]).Hash()
right := Evidences(evs[(len(evs)+1)/2:]).Hash()
return merkle.SimpleHashFromTwoHashes(left, right)
}
}
//-------------------------------------------
// DuplicateVoteEvidence contains evidence a validator signed two conflicting votes.
type DuplicateVoteEvidence struct {
PubKey crypto.PubKey
VoteA *Vote
VoteB *Vote
}
// String returns a string representation of the evidence.
func (dve *DuplicateVoteEvidence) String() string {
return fmt.Sprintf("VoteA: %v; VoteB: %v", dve.VoteA, dve.VoteB)
}
// Address returns the address of the validator.
func (dve *DuplicateVoteEvidence) Address() []byte {
return dve.PubKey.Address()
}
// Hash returns the hash of the evidence.
func (dve *DuplicateVoteEvidence) Hash() []byte {
return merkle.SimpleHashFromBinary(dve)
}
// Verify returns an error if the two votes aren't conflicting.
// To be conflicting, they must be from the same validator, for the same H/R/S, but for different blocks.
func (dve *DuplicateVoteEvidence) Verify(chainID string) error {
// H/R/S must be the same
if dve.VoteA.Height != dve.VoteB.Height ||
dve.VoteA.Round != dve.VoteB.Round ||
dve.VoteA.Type != dve.VoteB.Type {
return fmt.Errorf("DuplicateVoteEvidence Error: H/R/S does not match. Got %v and %v", dve.VoteA, dve.VoteB)
}
// Address must be the same
if !bytes.Equal(dve.VoteA.ValidatorAddress, dve.VoteB.ValidatorAddress) {
return fmt.Errorf("DuplicateVoteEvidence Error: Validator addresses do not match. Got %X and %X", dve.VoteA.ValidatorAddress, dve.VoteB.ValidatorAddress)
}
// XXX: Should we enforce index is the same ?
if dve.VoteA.ValidatorIndex != dve.VoteB.ValidatorIndex {
return fmt.Errorf("DuplicateVoteEvidence Error: Validator indices do not match. Got %d and %d", dve.VoteA.ValidatorIndex, dve.VoteB.ValidatorIndex)
}
// BlockIDs must be different
if dve.VoteA.BlockID.Equals(dve.VoteB.BlockID) {
return fmt.Errorf("DuplicateVoteEvidence Error: BlockIDs are the same (%v) - not a real duplicate vote!", dve.VoteA.BlockID)
}
// Signatures must be valid
if !dve.PubKey.VerifyBytes(SignBytes(chainID, dve.VoteA), dve.VoteA.Signature) {
return ErrVoteInvalidSignature
}
if !dve.PubKey.VerifyBytes(SignBytes(chainID, dve.VoteB), dve.VoteB.Signature) {
return ErrVoteInvalidSignature
}
return nil
}