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package types
import (
"bytes"
"fmt"
"strings"
"sync"
. "github.com/tendermint/go-common"
)
/*
VoteSet helps collect signatures from validators at each height+round for a
predefined vote type.
We need VoteSet to be able to keep track of conflicting votes when validators
double-sign. Yet, we can't keep track of *all* the votes seen, as that could
be a DoS attack vector.
There are two storage areas for votes.
1. voteSet.votes
2. voteSet.votesByBlock
`.votes` is the "canonical" list of votes. It always has at least one vote,
if a vote from a validator had been seen at all. Usually it keeps track of
the first vote seen, but when a 2/3 majority is found, votes for that get
priority and are copied over from `.votesByBlock`.
`.votesByBlock` keeps track of a list of votes for a particular block. There
are two ways a &blockVotes{} gets created in `.votesByBlock`.
1. the first vote seen by a validator was for the particular block.
2. a peer claims to have seen 2/3 majority for the particular block.
Since the first vote from a validator will always get added in `.votesByBlock`
, all votes in `.votes` will have a corresponding entry in `.votesByBlock`.
When a &blockVotes{} in `.votesByBlock` reaches a 2/3 majority quorum, its
votes are copied into `.votes`.
All this is memory bounded because conflicting votes only get added if a peer
told us to track that block, each peer only gets to tell us 1 such block, and,
there's only a limited number of peers.
NOTE: Assumes that the sum total of voting power does not exceed MaxUInt64.
*/
type VoteSet struct {
chainID string
height int
round int
type_ byte
mtx sync.Mutex
valSet *ValidatorSet
votesBitArray *BitArray
votes []*Vote // Primary votes to share
sum int64 // Sum of voting power for seen votes, discounting conflicts
maj23 *BlockID // First 2/3 majority seen
votesByBlock map[string]*blockVotes // string(blockHash|blockParts) -> blockVotes
peerMaj23s map[string]BlockID // Maj23 for each peer
}
// Constructs a new VoteSet struct used to accumulate votes for given height/round.
func NewVoteSet(chainID string, height int, round int, type_ byte, valSet *ValidatorSet) *VoteSet {
if height == 0 {
PanicSanity("Cannot make VoteSet for height == 0, doesn't make sense.")
}
return &VoteSet{
chainID: chainID,
height: height,
round: round,
type_: type_,
valSet: valSet,
votesBitArray: NewBitArray(valSet.Size()),
votes: make([]*Vote, valSet.Size()),
sum: 0,
maj23: nil,
votesByBlock: make(map[string]*blockVotes, valSet.Size()),
peerMaj23s: make(map[string]BlockID),
}
}
func (voteSet *VoteSet) ChainID() string {
return voteSet.chainID
}
func (voteSet *VoteSet) Height() int {
if voteSet == nil {
return 0
} else {
return voteSet.height
}
}
func (voteSet *VoteSet) Round() int {
if voteSet == nil {
return -1
} else {
return voteSet.round
}
}
func (voteSet *VoteSet) Type() byte {
if voteSet == nil {
return 0x00
} else {
return voteSet.type_
}
}
func (voteSet *VoteSet) Size() int {
if voteSet == nil {
return 0
} else {
return voteSet.valSet.Size()
}
}
// Returns added=true if vote is valid and new.
// Otherwise returns err=ErrVote[
// UnexpectedStep | InvalidIndex | InvalidAddress |
// InvalidSignature | InvalidBlockHash | ConflictingVotes ]
// Duplicate votes return added=false, err=nil.
// Conflicting votes return added=*, err=ErrVoteConflictingVotes.
// NOTE: vote should not be mutated after adding.
func (voteSet *VoteSet) AddVote(vote *Vote) (added bool, err error) {
voteSet.mtx.Lock()
defer voteSet.mtx.Unlock()
return voteSet.addVote(vote)
}
// NOTE: Validates as much as possible before attempting to verify the signature.
func (voteSet *VoteSet) addVote(vote *Vote) (added bool, err error) {
valIndex := vote.ValidatorIndex
valAddr := vote.ValidatorAddress
blockKey := vote.BlockID.Key()
// Ensure that validator index was set
if valIndex < 0 || len(valAddr) == 0 {
panic("Validator index or address was not set in vote.")
}
// Make sure the step matches.
if (vote.Height != voteSet.height) ||
(vote.Round != voteSet.round) ||
(vote.Type != voteSet.type_) {
return false, ErrVoteUnexpectedStep
}
// Ensure that signer is a validator.
lookupAddr, val := voteSet.valSet.GetByIndex(valIndex)
if val == nil {
return false, ErrVoteInvalidValidatorIndex
}
// Ensure that the signer has the right address
if !bytes.Equal(valAddr, lookupAddr) {
return false, ErrVoteInvalidValidatorAddress
}
// If we already know of this vote, return false.
if existing, ok := voteSet.getVote(valIndex, blockKey); ok {
if existing.Signature.Equals(vote.Signature) {
return false, nil // duplicate
} else {
return false, ErrVoteInvalidSignature // NOTE: assumes deterministic signatures
}
}
// Check signature.
if !val.PubKey.VerifyBytes(SignBytes(voteSet.chainID, vote), vote.Signature) {
// Bad signature.
return false, ErrVoteInvalidSignature
}
// Add vote and get conflicting vote if any
added, conflicting := voteSet.addVerifiedVote(vote, blockKey, val.VotingPower)
if conflicting != nil {
return added, &ErrVoteConflictingVotes{
VoteA: conflicting,
VoteB: vote,
}
} else {
if !added {
PanicSanity("Expected to add non-conflicting vote")
}
return added, nil
}
}
// Returns (vote, true) if vote exists for valIndex and blockKey
func (voteSet *VoteSet) getVote(valIndex int, blockKey string) (vote *Vote, ok bool) {
if existing := voteSet.votes[valIndex]; existing != nil && existing.BlockID.Key() == blockKey {
return existing, true
}
if existing := voteSet.votesByBlock[blockKey].getByIndex(valIndex); existing != nil {
return existing, true
}
return nil, false
}
// Assumes signature is valid.
// If conflicting vote exists, returns it.
func (voteSet *VoteSet) addVerifiedVote(vote *Vote, blockKey string, votingPower int64) (added bool, conflicting *Vote) {
valIndex := vote.ValidatorIndex
// Already exists in voteSet.votes?
if existing := voteSet.votes[valIndex]; existing != nil {
if existing.BlockID.Equals(vote.BlockID) {
PanicSanity("addVerifiedVote does not expect duplicate votes")
} else {
conflicting = existing
}
// Replace vote if blockKey matches voteSet.maj23.
if voteSet.maj23 != nil && voteSet.maj23.Key() == blockKey {
voteSet.votes[valIndex] = vote
voteSet.votesBitArray.SetIndex(valIndex, true)
}
// Otherwise don't add it to voteSet.votes
} else {
// Add to voteSet.votes and incr .sum
voteSet.votes[valIndex] = vote
voteSet.votesBitArray.SetIndex(valIndex, true)
voteSet.sum += votingPower
}
votesByBlock, ok := voteSet.votesByBlock[blockKey]
if ok {
if conflicting != nil && !votesByBlock.peerMaj23 {
// There's a conflict and no peer claims that this block is special.
return false, conflicting
}
// We'll add the vote in a bit.
} else {
// .votesByBlock doesn't exist...
if conflicting != nil {
// ... and there's a conflicting vote.
// We're not even tracking this blockKey, so just forget it.
return false, conflicting
} else {
// ... and there's no conflicting vote.
// Start tracking this blockKey
votesByBlock = newBlockVotes(false, voteSet.valSet.Size())
voteSet.votesByBlock[blockKey] = votesByBlock
// We'll add the vote in a bit.
}
}
// Before adding to votesByBlock, see if we'll exceed quorum
origSum := votesByBlock.sum
quorum := voteSet.valSet.TotalVotingPower()*2/3 + 1
// Add vote to votesByBlock
votesByBlock.addVerifiedVote(vote, votingPower)
// If we just crossed the quorum threshold and have 2/3 majority...
if origSum < quorum && quorum <= votesByBlock.sum {
// Only consider the first quorum reached
if voteSet.maj23 == nil {
maj23BlockID := vote.BlockID
voteSet.maj23 = &maj23BlockID
// And also copy votes over to voteSet.votes
for i, vote := range votesByBlock.votes {
if vote != nil {
voteSet.votes[i] = vote
}
}
}
}
return true, conflicting
}
// If a peer claims that it has 2/3 majority for given blockKey, call this.
// NOTE: if there are too many peers, or too much peer churn,
// this can cause memory issues.
// TODO: implement ability to remove peers too
func (voteSet *VoteSet) SetPeerMaj23(peerID string, blockID BlockID) {
voteSet.mtx.Lock()
defer voteSet.mtx.Unlock()
blockKey := blockID.Key()
// Make sure peer hasn't already told us something.
if existing, ok := voteSet.peerMaj23s[peerID]; ok {
if existing.Equals(blockID) {
return // Nothing to do
} else {
return // TODO bad peer!
}
}
voteSet.peerMaj23s[peerID] = blockID
// Create .votesByBlock entry if needed.
votesByBlock, ok := voteSet.votesByBlock[blockKey]
if ok {
if votesByBlock.peerMaj23 {
return // Nothing to do
} else {
votesByBlock.peerMaj23 = true
// No need to copy votes, already there.
}
} else {
votesByBlock = newBlockVotes(true, voteSet.valSet.Size())
voteSet.votesByBlock[blockKey] = votesByBlock
// No need to copy votes, no votes to copy over.
}
}
func (voteSet *VoteSet) BitArray() *BitArray {
if voteSet == nil {
return nil
}
voteSet.mtx.Lock()
defer voteSet.mtx.Unlock()
return voteSet.votesBitArray.Copy()
}
func (voteSet *VoteSet) BitArrayByBlockID(blockID BlockID) *BitArray {
if voteSet == nil {
return nil
}
voteSet.mtx.Lock()
defer voteSet.mtx.Unlock()
votesByBlock, ok := voteSet.votesByBlock[blockID.Key()]
if ok {
return votesByBlock.bitArray.Copy()
}
return nil
}
// NOTE: if validator has conflicting votes, returns "canonical" vote
func (voteSet *VoteSet) GetByIndex(valIndex int) *Vote {
voteSet.mtx.Lock()
defer voteSet.mtx.Unlock()
return voteSet.votes[valIndex]
}
func (voteSet *VoteSet) GetByAddress(address []byte) *Vote {
voteSet.mtx.Lock()
defer voteSet.mtx.Unlock()
valIndex, val := voteSet.valSet.GetByAddress(address)
if val == nil {
PanicSanity("GetByAddress(address) returned nil")
}
return voteSet.votes[valIndex]
}
func (voteSet *VoteSet) HasTwoThirdsMajority() bool {
if voteSet == nil {
return false
}
voteSet.mtx.Lock()
defer voteSet.mtx.Unlock()
return voteSet.maj23 != nil
}
func (voteSet *VoteSet) IsCommit() bool {
if voteSet == nil {
return false
}
if voteSet.type_ != VoteTypePrecommit {
return false
}
voteSet.mtx.Lock()
defer voteSet.mtx.Unlock()
return voteSet.maj23 != nil
}
func (voteSet *VoteSet) HasTwoThirdsAny() bool {
if voteSet == nil {
return false
}
voteSet.mtx.Lock()
defer voteSet.mtx.Unlock()
return voteSet.sum > voteSet.valSet.TotalVotingPower()*2/3
}
// Returns either a blockhash (or nil) that received +2/3 majority.
// If there exists no such majority, returns (nil, PartSetHeader{}, false).
func (voteSet *VoteSet) TwoThirdsMajority() (blockID BlockID, ok bool) {
voteSet.mtx.Lock()
defer voteSet.mtx.Unlock()
if voteSet.maj23 != nil {
return *voteSet.maj23, true
} else {
return BlockID{}, false
}
}
func (voteSet *VoteSet) String() string {
if voteSet == nil {
return "nil-VoteSet"
}
return voteSet.StringIndented("")
}
func (voteSet *VoteSet) StringIndented(indent string) string {
voteStrings := make([]string, len(voteSet.votes))
for i, vote := range voteSet.votes {
if vote == nil {
voteStrings[i] = "nil-Vote"
} else {
voteStrings[i] = vote.String()
}
}
return fmt.Sprintf(`VoteSet{
%s H:%v R:%v T:%v
%s %v
%s %v
%s %v
%s}`,
indent, voteSet.height, voteSet.round, voteSet.type_,
indent, strings.Join(voteStrings, "\n"+indent+" "),
indent, voteSet.votesBitArray,
indent, voteSet.peerMaj23s,
indent)
}
func (voteSet *VoteSet) StringShort() string {
if voteSet == nil {
return "nil-VoteSet"
}
voteSet.mtx.Lock()
defer voteSet.mtx.Unlock()
return fmt.Sprintf(`VoteSet{H:%v R:%v T:%v +2/3:%v %v %v}`,
voteSet.height, voteSet.round, voteSet.type_, voteSet.maj23, voteSet.votesBitArray, voteSet.peerMaj23s)
}
//--------------------------------------------------------------------------------
// Commit
func (voteSet *VoteSet) MakeCommit() *Commit {
if voteSet.type_ != VoteTypePrecommit {
PanicSanity("Cannot MakeCommit() unless VoteSet.Type is VoteTypePrecommit")
}
voteSet.mtx.Lock()
defer voteSet.mtx.Unlock()
// Make sure we have a 2/3 majority
if voteSet.maj23 == nil {
PanicSanity("Cannot MakeCommit() unless a blockhash has +2/3")
}
// For every validator, get the precommit
votesCopy := make([]*Vote, len(voteSet.votes))
copy(votesCopy, voteSet.votes)
return &Commit{
BlockID: *voteSet.maj23,
Precommits: votesCopy,
}
}
//--------------------------------------------------------------------------------
/*
Votes for a particular block
There are two ways a *blockVotes gets created for a blockKey.
1. first (non-conflicting) vote of a validator w/ blockKey (peerMaj23=false)
2. A peer claims to have a 2/3 majority w/ blockKey (peerMaj23=true)
*/
type blockVotes struct {
peerMaj23 bool // peer claims to have maj23
bitArray *BitArray // valIndex -> hasVote?
votes []*Vote // valIndex -> *Vote
sum int64 // vote sum
}
func newBlockVotes(peerMaj23 bool, numValidators int) *blockVotes {
return &blockVotes{
peerMaj23: peerMaj23,
bitArray: NewBitArray(numValidators),
votes: make([]*Vote, numValidators),
sum: 0,
}
}
func (vs *blockVotes) addVerifiedVote(vote *Vote, votingPower int64) {
valIndex := vote.ValidatorIndex
if existing := vs.votes[valIndex]; existing == nil {
vs.bitArray.SetIndex(valIndex, true)
vs.votes[valIndex] = vote
vs.sum += votingPower
}
}
func (vs *blockVotes) getByIndex(index int) *Vote {
if vs == nil {
return nil
}
return vs.votes[index]
}
//--------------------------------------------------------------------------------
// Common interface between *consensus.VoteSet and types.Commit
type VoteSetReader interface {
Height() int
Round() int
Type() byte
Size() int
BitArray() *BitArray
GetByIndex(int) *Vote
IsCommit() bool
}