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