package types import ( "bytes" "fmt" "strings" "sync" . "github.com/tendermint/tmlibs/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. // NOTE: VoteSet must not be nil func (voteSet *VoteSet) AddVote(vote *Vote) (added bool, err error) { if voteSet == nil { PanicSanity("AddVote() on nil VoteSet") } 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 { return false, ErrVoteInvalidValidatorIndex } else if len(valAddr) == 0 { return false, ErrVoteInvalidValidatorAddress } // 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 // NOTE: VoteSet must not be nil func (voteSet *VoteSet) SetPeerMaj23(peerID string, blockID BlockID) { if voteSet == nil { PanicSanity("SetPeerMaj23() on nil VoteSet") } 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 { if voteSet == nil { return nil } voteSet.mtx.Lock() defer voteSet.mtx.Unlock() return voteSet.votes[valIndex] } func (voteSet *VoteSet) GetByAddress(address []byte) *Vote { if voteSet == nil { return nil } 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 } func (voteSet *VoteSet) HasAll() bool { return voteSet.sum == voteSet.valSet.TotalVotingPower() } // 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) { if voteSet == nil { return BlockID{}, false } 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 }