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epoch.go
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epoch.go
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package flow
import (
"bytes"
"encoding/json"
"fmt"
"io"
"github.com/ethereum/go-ethereum/rlp"
"github.com/fxamacker/cbor/v2"
"github.com/vmihailenco/msgpack/v4"
"github.com/onflow/flow-go/crypto"
"github.com/onflow/flow-go/model/encodable"
)
// EpochPhase represents a phase of the Epoch Preparation Protocol. The phase
// of an epoch is resolved based on a block reference and is fork-dependent.
// An epoch begins in the staking phase, then transitions to the setup phase in
// the block containing the EpochSetup service event, then to the committed
// phase in the block containing the EpochCommit service event.
// |<-- EpochPhaseStaking -->|<-- EpochPhaseSetup -->|<-- EpochPhaseCommitted -->|<-- EpochPhaseStaking -->...
// |<------------------------------- Epoch N ------------------------------------>|<-- Epoch N + 1 --...
type EpochPhase int
const (
EpochPhaseUndefined EpochPhase = iota
EpochPhaseStaking
EpochPhaseSetup
EpochPhaseCommitted
)
func (p EpochPhase) String() string {
return [...]string{
"EpochPhaseUndefined",
"EpochPhaseStaking",
"EpochPhaseSetup",
"EpochPhaseCommitted",
}[p]
}
func GetEpochPhase(phase string) EpochPhase {
phases := []EpochPhase{
EpochPhaseUndefined,
EpochPhaseStaking,
EpochPhaseSetup,
EpochPhaseCommitted,
}
for _, p := range phases {
if p.String() == phase {
return p
}
}
return EpochPhaseUndefined
}
// EpochSetupRandomSourceLength is the required length of the random source
// included in an EpochSetup service event.
const EpochSetupRandomSourceLength = 16
// EpochSetup is a service event emitted when the network is ready to set up
// for the upcoming epoch. It contains the participants in the epoch, the
// length, the cluster assignment, and the seed for leader selection.
type EpochSetup struct {
Counter uint64 // the number of the epoch
FirstView uint64 // the first view of the epoch
DKGPhase1FinalView uint64 // the final view of DKG phase 1
DKGPhase2FinalView uint64 // the final view of DKG phase 2
DKGPhase3FinalView uint64 // the final view of DKG phase 3
FinalView uint64 // the final view of the epoch
Participants IdentityList // all participants of the epoch
Assignments AssignmentList // cluster assignment for the epoch
RandomSource []byte // source of randomness for epoch-specific setup tasks
}
func (setup *EpochSetup) ServiceEvent() ServiceEvent {
return ServiceEvent{
Type: ServiceEventSetup,
Event: setup,
}
}
// ID returns the hash of the event contents.
func (setup *EpochSetup) ID() Identifier {
return MakeID(setup)
}
func (setup *EpochSetup) EqualTo(other *EpochSetup) bool {
if setup.Counter != other.Counter {
return false
}
if setup.FirstView != other.FirstView {
return false
}
if setup.DKGPhase1FinalView != other.DKGPhase1FinalView {
return false
}
if setup.DKGPhase2FinalView != other.DKGPhase2FinalView {
return false
}
if setup.DKGPhase3FinalView != other.DKGPhase3FinalView {
return false
}
if setup.FinalView != other.FinalView {
return false
}
if !setup.Participants.EqualTo(other.Participants) {
return false
}
if !setup.Assignments.EqualTo(other.Assignments) {
return false
}
return bytes.Equal(setup.RandomSource, other.RandomSource)
}
// EpochCommit is a service event emitted when epoch setup has been completed.
// When an EpochCommit event is emitted, the network is ready to transition to
// the epoch.
type EpochCommit struct {
Counter uint64 // the number of the epoch
ClusterQCs []ClusterQCVoteData // quorum certificates for each cluster
DKGGroupKey crypto.PublicKey // group key from DKG
DKGParticipantKeys []crypto.PublicKey // public keys for DKG participants
}
// ClusterQCVoteData represents the votes for a cluster quorum certificate, as
// gathered by the ClusterQC smart contract. It contains the aggregated
// signature over the root block for the cluster as well as the set of voters.
type ClusterQCVoteData struct {
SigData crypto.Signature // the aggregated signature over all the votes
VoterIDs []Identifier // the set of voters that contributed to the qc
}
func (c *ClusterQCVoteData) EqualTo(other *ClusterQCVoteData) bool {
if len(c.VoterIDs) != len(other.VoterIDs) {
return false
}
if !bytes.Equal(c.SigData, other.SigData) {
return false
}
for i, v := range c.VoterIDs {
if v != other.VoterIDs[i] {
return false
}
}
return true
}
// ClusterQCVoteDataFromQC converts a quorum certificate to the representation
// used by the smart contract, essentially discarding the block ID and view
// (which are protocol-defined given the EpochSetup event).
func ClusterQCVoteDataFromQC(qc *QuorumCertificateWithSignerIDs) ClusterQCVoteData {
return ClusterQCVoteData{
SigData: qc.SigData,
VoterIDs: qc.SignerIDs,
}
}
func ClusterQCVoteDatasFromQCs(qcs []*QuorumCertificateWithSignerIDs) []ClusterQCVoteData {
qcVotes := make([]ClusterQCVoteData, 0, len(qcs))
for _, qc := range qcs {
qcVotes = append(qcVotes, ClusterQCVoteDataFromQC(qc))
}
return qcVotes
}
func (commit *EpochCommit) ServiceEvent() ServiceEvent {
return ServiceEvent{
Type: ServiceEventCommit,
Event: commit,
}
}
type encodableCommit struct {
Counter uint64
ClusterQCs []ClusterQCVoteData
DKGGroupKey encodable.RandomBeaconPubKey
DKGParticipantKeys []encodable.RandomBeaconPubKey
}
func encodableFromCommit(commit *EpochCommit) encodableCommit {
encKeys := make([]encodable.RandomBeaconPubKey, 0, len(commit.DKGParticipantKeys))
for _, key := range commit.DKGParticipantKeys {
encKeys = append(encKeys, encodable.RandomBeaconPubKey{PublicKey: key})
}
return encodableCommit{
Counter: commit.Counter,
ClusterQCs: commit.ClusterQCs,
DKGGroupKey: encodable.RandomBeaconPubKey{PublicKey: commit.DKGGroupKey},
DKGParticipantKeys: encKeys,
}
}
func commitFromEncodable(enc encodableCommit) EpochCommit {
dkgKeys := make([]crypto.PublicKey, 0, len(enc.DKGParticipantKeys))
for _, key := range enc.DKGParticipantKeys {
dkgKeys = append(dkgKeys, key.PublicKey)
}
return EpochCommit{
Counter: enc.Counter,
ClusterQCs: enc.ClusterQCs,
DKGGroupKey: enc.DKGGroupKey.PublicKey,
DKGParticipantKeys: dkgKeys,
}
}
func (commit EpochCommit) MarshalJSON() ([]byte, error) {
return json.Marshal(encodableFromCommit(&commit))
}
func (commit *EpochCommit) UnmarshalJSON(b []byte) error {
var enc encodableCommit
err := json.Unmarshal(b, &enc)
if err != nil {
return err
}
*commit = commitFromEncodable(enc)
return nil
}
func (commit *EpochCommit) MarshalCBOR() ([]byte, error) {
return cbor.Marshal(encodableFromCommit(commit))
}
func (commit *EpochCommit) UnmarshalCBOR(b []byte) error {
var enc encodableCommit
err := cbor.Unmarshal(b, &enc)
if err != nil {
return err
}
*commit = commitFromEncodable(enc)
return nil
}
func (commit *EpochCommit) MarshalMsgpack() ([]byte, error) {
return msgpack.Marshal(encodableFromCommit(commit))
}
func (commit *EpochCommit) UnmarshalMsgpack(b []byte) error {
var enc encodableCommit
err := msgpack.Unmarshal(b, &enc)
if err != nil {
return err
}
*commit = commitFromEncodable(enc)
return nil
}
// EncodeRLP encodes the commit as RLP. The RLP encoding needs to be handled
// differently from JSON/msgpack, because it does not handle custom encoders
// within map types.
// NOTE: DecodeRLP is not needed, as this is only used for hashing.
func (commit *EpochCommit) EncodeRLP(w io.Writer) error {
rlpEncodable := struct {
Counter uint64
ClusterQCs []ClusterQCVoteData
DKGGroupKey []byte
DKGParticipantKeys [][]byte
}{
Counter: commit.Counter,
ClusterQCs: commit.ClusterQCs,
DKGGroupKey: commit.DKGGroupKey.Encode(),
DKGParticipantKeys: make([][]byte, 0, len(commit.DKGParticipantKeys)),
}
for _, key := range commit.DKGParticipantKeys {
rlpEncodable.DKGParticipantKeys = append(rlpEncodable.DKGParticipantKeys, key.Encode())
}
return rlp.Encode(w, rlpEncodable)
}
// ID returns the hash of the event contents.
func (commit *EpochCommit) ID() Identifier {
return MakeID(commit)
}
func (commit *EpochCommit) EqualTo(other *EpochCommit) bool {
if commit.Counter != other.Counter {
return false
}
if len(commit.ClusterQCs) != len(other.ClusterQCs) {
return false
}
for i, qc := range commit.ClusterQCs {
if !qc.EqualTo(&other.ClusterQCs[i]) {
return false
}
}
if (commit.DKGGroupKey == nil && other.DKGGroupKey != nil) ||
(commit.DKGGroupKey != nil && other.DKGGroupKey == nil) {
return false
}
if commit.DKGGroupKey != nil && other.DKGGroupKey != nil && !commit.DKGGroupKey.Equals(other.DKGGroupKey) {
return false
}
if len(commit.DKGParticipantKeys) != len(other.DKGParticipantKeys) {
return false
}
for i, key := range commit.DKGParticipantKeys {
if !key.Equals(other.DKGParticipantKeys[i]) {
return false
}
}
return true
}
// ToDKGParticipantLookup constructs a DKG participant lookup from an identity
// list and a key list. The identity list must be EXACTLY the same (order and
// contents) as that used when initializing the corresponding DKG instance.
func ToDKGParticipantLookup(participants IdentityList, keys []crypto.PublicKey) (map[Identifier]DKGParticipant, error) {
if len(participants) != len(keys) {
return nil, fmt.Errorf("participant list (len=%d) does not match key list (len=%d)", len(participants), len(keys))
}
lookup := make(map[Identifier]DKGParticipant, len(participants))
for i := 0; i < len(participants); i++ {
part := participants[i]
key := keys[i]
lookup[part.NodeID] = DKGParticipant{
Index: uint(i),
KeyShare: key,
}
}
return lookup, nil
}
type DKGParticipant struct {
Index uint
KeyShare crypto.PublicKey
}
type encodableDKGParticipant struct {
Index uint
KeyShare encodable.RandomBeaconPubKey
}
func encodableFromDKGParticipant(part DKGParticipant) encodableDKGParticipant {
return encodableDKGParticipant{
Index: part.Index,
KeyShare: encodable.RandomBeaconPubKey{PublicKey: part.KeyShare},
}
}
func dkgParticipantFromEncodable(enc encodableDKGParticipant) DKGParticipant {
return DKGParticipant{
Index: enc.Index,
KeyShare: enc.KeyShare.PublicKey,
}
}
func (part DKGParticipant) MarshalJSON() ([]byte, error) {
enc := encodableFromDKGParticipant(part)
return json.Marshal(enc)
}
func (part *DKGParticipant) UnmarshalJSON(b []byte) error {
var enc encodableDKGParticipant
err := json.Unmarshal(b, &enc)
if err != nil {
return err
}
*part = dkgParticipantFromEncodable(enc)
return nil
}
func (part DKGParticipant) MarshalCBOR() ([]byte, error) {
enc := encodableFromDKGParticipant(part)
return cbor.Marshal(enc)
}
func (part *DKGParticipant) UnmarshalCBOR(b []byte) error {
var enc encodableDKGParticipant
err := cbor.Unmarshal(b, &enc)
if err != nil {
return err
}
*part = dkgParticipantFromEncodable(enc)
return nil
}
func (part DKGParticipant) MarshalMsgpack() ([]byte, error) {
return msgpack.Marshal(encodableFromDKGParticipant(part))
}
func (part *DKGParticipant) UnmarshalMsgpack(b []byte) error {
var enc encodableDKGParticipant
err := msgpack.Unmarshal(b, &enc)
if err != nil {
return err
}
*part = dkgParticipantFromEncodable(enc)
return nil
}
func (part DKGParticipant) EncodeRLP(w io.Writer) error {
return rlp.Encode(w, encodableFromDKGParticipant(part))
}
// EpochStatus represents the status of the current and next epoch with respect
// to a reference block. Concretely, it contains the IDs for all relevant
// service events emitted as of the reference block. Events not yet emitted are
// represented by ZeroID.
type EpochStatus struct {
PreviousEpoch EventIDs // EpochSetup and EpochCommit events for the previous epoch
CurrentEpoch EventIDs // EpochSetup and EpochCommit events for the current epoch
NextEpoch EventIDs // EpochSetup and EpochCommit events for the next epoch
// InvalidServiceEventIncorporated encodes whether an invalid service event is
// incorporated in this fork. When this happens, epoch fallback is triggered
// AFTER the fork is finalized.
InvalidServiceEventIncorporated bool
}
// Copy returns a copy of the epoch status.
func (es *EpochStatus) Copy() *EpochStatus {
return &EpochStatus{
PreviousEpoch: es.PreviousEpoch,
CurrentEpoch: es.CurrentEpoch,
NextEpoch: es.NextEpoch,
}
}
// EventIDs is a container for IDs of epoch service events.
type EventIDs struct {
// SetupID is the ID of the EpochSetup event for the respective Epoch
SetupID Identifier
// CommitID is the ID of the EpochCommit event for the respective Epoch
CommitID Identifier
}
func NewEpochStatus(previousSetup, previousCommit, currentSetup, currentCommit, nextSetup, nextCommit Identifier) (*EpochStatus, error) {
status := &EpochStatus{
PreviousEpoch: EventIDs{
SetupID: previousSetup,
CommitID: previousCommit,
},
CurrentEpoch: EventIDs{
SetupID: currentSetup,
CommitID: currentCommit,
},
NextEpoch: EventIDs{
SetupID: nextSetup,
CommitID: nextCommit,
},
}
err := status.Check()
if err != nil {
return nil, err
}
return status, nil
}
// Check checks that the status is well-formed, returning an error if it is not.
// All errors indicate a malformed EpochStatus.
func (es *EpochStatus) Check() error {
if es == nil {
return fmt.Errorf("nil epoch status")
}
// must reference either both or neither event IDs for previous epoch
if (es.PreviousEpoch.SetupID == ZeroID) != (es.PreviousEpoch.CommitID == ZeroID) {
return fmt.Errorf("epoch status with only setup or only commit service event")
}
// must reference event IDs for current epoch
if es.CurrentEpoch.SetupID == ZeroID || es.CurrentEpoch.CommitID == ZeroID {
return fmt.Errorf("epoch status with empty current epoch service events")
}
// must not reference a commit without a setup
if es.NextEpoch.SetupID == ZeroID && es.NextEpoch.CommitID != ZeroID {
return fmt.Errorf("epoch status with commit but no setup service event")
}
return nil
}
// Phase returns the phase for the CURRENT epoch, given this epoch status.
// All errors indicate a malformed EpochStatus.
func (es *EpochStatus) Phase() (EpochPhase, error) {
err := es.Check()
if err != nil {
return EpochPhaseUndefined, err
}
if es.NextEpoch.SetupID == ZeroID {
return EpochPhaseStaking, nil
}
if es.NextEpoch.CommitID == ZeroID {
return EpochPhaseSetup, nil
}
return EpochPhaseCommitted, nil
}
func (es *EpochStatus) HasPrevious() bool {
return es.PreviousEpoch.SetupID != ZeroID && es.PreviousEpoch.CommitID != ZeroID
}