vote.go

package concord

import (
	"bytes"
	"errors"
	"fmt"
	"time"

	"github.com/tendermint/tendermint/crypto"
	tmbytes "github.com/tendermint/tendermint/libs/bytes"
	"github.com/tendermint/tendermint/libs/protoio"

	"github.com/Wondertan/iotwal/concord/pb"
)

const (
	nilVoteStr string = "nil-Vote"
)

var (
	ErrVoteUnexpectedStep            = errors.New("unexpected step")
	ErrVoteInvalidValidatorIndex     = errors.New("invalid validator index")
	ErrVoteInvalidValidatorAddress   = errors.New("invalid validator address")
	ErrVoteInvalidSignature          = errors.New("invalid signature")
	ErrVoteInvalidDataHash           = errors.New("invalid data hash")
	ErrVoteNonDeterministicSignature = errors.New("non-deterministic signature")
	ErrVoteNil                       = errors.New("nil vote")
	ErrVoteInvalidType               = errors.New("invalid vote type")
)

type ErrVoteConflictingVotes struct {
	VoteA *Vote
	VoteB *Vote
}

func (err *ErrVoteConflictingVotes) Error() string {
	return fmt.Sprintf("conflicting votes from validator %X", err.VoteA.ValidatorAddress)
}

func NewConflictingVoteError(vote1, vote2 *Vote) *ErrVoteConflictingVotes {
	return &ErrVoteConflictingVotes{
		VoteA: vote1,
		VoteB: vote2,
	}
}

// Address is hex bytes.
type Address = crypto.Address

// Vote represents a prevote, precommit, or commit vote from validators for
// consensus.
type Vote struct {
	Type             pb.SignedMsgType `json:"type"`
	DataHash         DataHash         `json:"block_id"` // zero if vote is nil.
	Timestamp        time.Time        `json:"timestamp"`
	ValidatorAddress Address          `json:"validator_address"`
	ValidatorIndex   int32            `json:"validator_index"`
	Signature        []byte           `json:"signature"`
}

func NewVote(t pb.SignedMsgType, round int32, index int32, address []byte, dataHash *DataHash) *Vote {
	return &Vote{Type: t, DataHash: *dataHash, ValidatorIndex: index, ValidatorAddress: address, Timestamp: time.Now()}
}

// CommitSig converts the Vote to a CommitSig.
func (vote *Vote) CommitSig() CommitSig {
	if vote == nil {
		return NewCommitSigAbsent()
	}

	var DataHashFlag DataHashFlag
	switch {
	case vote.DataHash.IsComplete():
		DataHashFlag = DataHashFlagCommit
	case vote.DataHash.IsZero():
		DataHashFlag = DataHashFlagNil
	default:
		panic(fmt.Sprintf("Invalid vote %v - expected DataHash to be either empty or complete", vote))
	}

	return CommitSig{
		DataHashFlag:     DataHashFlag,
		ValidatorAddress: vote.ValidatorAddress,
		Timestamp:        vote.Timestamp,
		Signature:        vote.Signature,
	}
}

// VoteSignBytes returns the proto-encoding of the canonicalized Vote, for
// signing. Panics is the marshaling fails.
//
// The encoded Protobuf message is varint length-prefixed (using MarshalDelimited)
// for backwards-compatibility with the Amino encoding, due to e.g. hardware
// devices that rely on this encoding.
//
// See CanonicalizeVote
func VoteSignBytes(chainID string, vote *pb.Vote) []byte {
	pb := CanonicalizeVote(chainID, vote)
	bz, err := protoio.MarshalDelimited(&pb)
	if err != nil {
		panic(err)
	}

	return bz
}

func (vote *Vote) Copy() *Vote {
	voteCopy := *vote
	return &voteCopy
}

// String returns a string representation of Vote.
//
// 1. validator index
// 2. first 6 bytes of validator address
// 3. height
// 4. round,
// 5. type byte
// 6. type string
// 7. first 6 bytes of block hash
// 8. first 6 bytes of signature
// 9. timestamp
func (vote *Vote) String() string {
	if vote == nil {
		return nilVoteStr
	}

	var typeString string
	switch vote.Type {
	case pb.PrevoteType:
		typeString = "Prevote"
	case pb.PrecommitType:
		typeString = "Precommit"
	default:
		panic("Unknown vote type")
	}

	return fmt.Sprintf("Vote{%v:%X %v(%v) %X %X @ %s}",
		vote.ValidatorIndex,
		tmbytes.Fingerprint(vote.ValidatorAddress),
		vote.Type,
		typeString,
		tmbytes.Fingerprint(vote.DataHash.Hash),
		tmbytes.Fingerprint(vote.Signature),
		CanonicalTime(vote.Timestamp),
	)
}

func (vote *Vote) Verify(chainID string, pubKey crypto.PubKey) error {
	if !bytes.Equal(pubKey.Address(), vote.ValidatorAddress) {
		return ErrVoteInvalidValidatorAddress
	}
	v := vote.ToProto()
	if !pubKey.VerifySignature(VoteSignBytes(chainID, v), vote.Signature) {
		return ErrVoteInvalidSignature
	}
	return nil
}

// ValidateBasic performs basic validation.
func (vote *Vote) ValidateBasic() error {
	if !IsVoteTypeValid(vote.Type) {
		return errors.New("invalid Type")
	}

	// NOTE: Timestamp validation is subtle and handled elsewhere.

	if err := vote.DataHash.ValidateBasic(); err != nil {
		return fmt.Errorf("wrong DataHash: %v", err)
	}

	// DataHash.ValidateBasic would not err if we for instance have an empty hash but a
	// non-empty PartsSetHeader:
	if !vote.DataHash.IsZero() && !vote.DataHash.IsComplete() {
		return fmt.Errorf("DataHash must be either empty or complete, got: %v", vote.DataHash)
	}

	if len(vote.ValidatorAddress) != crypto.AddressSize {
		return fmt.Errorf("expected ValidatorAddress size to be %d bytes, got %d bytes",
			crypto.AddressSize,
			len(vote.ValidatorAddress),
		)
	}
	if vote.ValidatorIndex < 0 {
		return errors.New("negative ValidatorIndex")
	}
	if len(vote.Signature) == 0 {
		return errors.New("signature is missing")
	}

	if len(vote.Signature) > MaxSignatureSize {
		return fmt.Errorf("signature is too big (max: %d)", MaxSignatureSize)
	}

	return nil
}

// ToProto converts the handwritten type to proto generated type
// return type, nil if everything converts safely, otherwise nil, error
func (vote *Vote) ToProto() *pb.Vote {
	if vote == nil {
		return nil
	}

	return &pb.Vote{
		Type:             vote.Type,
		DataHash:         *vote.DataHash.ToProto(),
		Timestamp:        vote.Timestamp,
		ValidatorAddress: vote.ValidatorAddress,
		ValidatorIndex:   vote.ValidatorIndex,
		Signature:        vote.Signature,
	}
}

// FromProto converts a proto generetad type to a handwritten type
// return type, nil if everything converts safely, otherwise nil, error
func VoteFromProto(pv *pb.Vote) (*Vote, error) {
	if pv == nil {
		return nil, errors.New("nil vote")
	}

	DataHash, err := DataHashFromProto(&pv.DataHash)
	if err != nil {
		return nil, err
	}

	vote := new(Vote)
	vote.Type = pv.Type
	vote.DataHash = *DataHash
	vote.Timestamp = pv.Timestamp
	vote.ValidatorAddress = pv.ValidatorAddress
	vote.ValidatorIndex = pv.ValidatorIndex
	vote.Signature = pv.Signature

	return vote, vote.ValidateBasic()
}

// IsVoteTypeValid returns true if t is a valid vote type.
func IsVoteTypeValid(t pb.SignedMsgType) bool {
	switch t {
	case pb.PrevoteType, pb.PrecommitType:
		return true
	default:
		return false
	}
}