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eligibility_validator.go
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/
eligibility_validator.go
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package proposals
import (
"context"
"errors"
"fmt"
"github.com/spacemeshos/fixed"
"github.com/spacemeshos/go-spacemesh/common/types"
"github.com/spacemeshos/go-spacemesh/datastore"
"github.com/spacemeshos/go-spacemesh/log"
"github.com/spacemeshos/go-spacemesh/sql/ballots"
"github.com/spacemeshos/go-spacemesh/system"
)
var (
errTargetEpochMismatch = errors.New("ATX target epoch and ballot publish epoch mismatch")
errPublicKeyMismatch = errors.New("ballot smesher key and ATX node key mismatch")
errIncorrectCounter = errors.New("proof counter larger than number of slots available")
errInvalidProofsOrder = errors.New("proofs are out of order")
errIncorrectVRFSig = errors.New("proof contains incorrect VRF signature")
errIncorrectLayerIndex = errors.New("ballot has incorrect layer index")
errIncorrectEligCount = errors.New("ballot has incorrect eligibility count")
)
// Validator validates the eligibility of a Ballot.
// the validation focuses on eligibility only and assumes the Ballot to be valid otherwise.
type Validator struct {
minActiveSetWeight uint64
avgLayerSize uint32
layersPerEpoch uint32
cdb *datastore.CachedDB
mesh meshProvider
beacons system.BeaconCollector
logger log.Log
vrfVerifier vrfVerifier
nonceFetcher nonceFetcher
}
type defaultFetcher struct {
cdb *datastore.CachedDB
}
func (f defaultFetcher) VRFNonce(nodeID types.NodeID, epoch types.EpochID) (types.VRFPostIndex, error) {
nonce, err := f.cdb.VRFNonce(nodeID, epoch)
if err != nil {
return types.VRFPostIndex(0), fmt.Errorf("get vrf nonce: %w", err)
}
return nonce, nil
}
// ValidatorOpt for configuring Validator.
type ValidatorOpt func(h *Validator)
func WithNonceFetcher(nf nonceFetcher) ValidatorOpt {
return func(h *Validator) {
h.nonceFetcher = nf
}
}
// NewEligibilityValidator returns a new EligibilityValidator.
func NewEligibilityValidator(
avgLayerSize, layersPerEpoch uint32, minActiveSetWeight uint64, cdb *datastore.CachedDB, bc system.BeaconCollector, m meshProvider, lg log.Log, vrfVerifier vrfVerifier, opts ...ValidatorOpt,
) *Validator {
v := &Validator{
minActiveSetWeight: minActiveSetWeight,
avgLayerSize: avgLayerSize,
layersPerEpoch: layersPerEpoch,
cdb: cdb,
mesh: m,
beacons: bc,
logger: lg,
vrfVerifier: vrfVerifier,
}
for _, opt := range opts {
opt(v)
}
if v.nonceFetcher == nil {
v.nonceFetcher = defaultFetcher{cdb: cdb}
}
return v
}
// CheckEligibility checks that a ballot is eligible in the layer that it specifies.
func (v *Validator) CheckEligibility(ctx context.Context, ballot *types.Ballot) (bool, error) {
var (
atxWeight, totalWeight uint64
err error
refBallot = ballot
epoch = ballot.Layer.GetEpoch()
)
if len(ballot.EligibilityProofs) == 0 {
return false, fmt.Errorf("empty eligibility list is invalid (ballot %s)", ballot.ID())
}
if ballot.RefBallot != types.EmptyBallotID {
if refBallot, err = ballots.Get(v.cdb, ballot.RefBallot); err != nil {
return false, fmt.Errorf("get ref ballot %v: %w", ballot.RefBallot, err)
}
}
if refBallot.EpochData == nil {
return false, fmt.Errorf("%w: ref ballot %v", errMissingEpochData, refBallot.ID())
}
if refBallot.AtxID != ballot.AtxID {
return false, fmt.Errorf("ballot (%v/%v) should be sharing atx with a reference ballot (%v/%v)", ballot.ID(), ballot.AtxID, refBallot.ID(), refBallot.AtxID)
}
beacon := refBallot.EpochData.Beacon
if beacon == types.EmptyBeacon {
return false, fmt.Errorf("%w: ref ballot %v", errMissingBeacon, refBallot.ID())
}
activeSets := refBallot.ActiveSet
if len(activeSets) == 0 {
return false, fmt.Errorf("%w: ref ballot %v", errEmptyActiveSet, refBallot.ID())
}
// todo: optimize by using reference to active set size and cache active set size to not load all atxsIDs from db
var owned *types.ActivationTxHeader
for _, atxID := range activeSets {
atx, err := v.cdb.GetAtxHeader(atxID)
if err != nil {
return false, fmt.Errorf("get ATX header %v: %w", atxID, err)
}
totalWeight += atx.GetWeight()
if atxID == ballot.AtxID {
owned = atx
}
}
if owned == nil {
return false, fmt.Errorf("atx %v from ballot %v (refballot %v) is not included into the active set", ballot.AtxID, ballot.ID(), refBallot.ID())
}
if targetEpoch := owned.TargetEpoch(); targetEpoch != epoch {
return false, fmt.Errorf("%w: ATX target epoch (%v), ballot publication epoch (%v)",
errTargetEpochMismatch, targetEpoch, epoch)
}
if ballot.SmesherID != owned.NodeID {
return false, fmt.Errorf("%w: public key (%v), ATX node key (%v)", errPublicKeyMismatch, ballot.SmesherID.String(), owned.NodeID)
}
atxWeight = owned.GetWeight()
numEligibleSlots, err := GetNumEligibleSlots(atxWeight, v.minActiveSetWeight, totalWeight, v.avgLayerSize, v.layersPerEpoch)
if err != nil {
return false, err
}
if ballot.EpochData != nil && ballot.EpochData.EligibilityCount != numEligibleSlots {
return false, fmt.Errorf("%w: expected %v, got: %v", errIncorrectEligCount, numEligibleSlots, ballot.EpochData.EligibilityCount)
}
var (
last uint32
isFirst = true
)
nonce, err := v.nonceFetcher.VRFNonce(ballot.SmesherID, epoch)
if err != nil {
return false, err
}
for _, proof := range ballot.EligibilityProofs {
counter := proof.J
if counter >= numEligibleSlots {
return false, fmt.Errorf("%w: proof counter (%d) numEligibleBallots (%d), totalWeight (%v)",
errIncorrectCounter, counter, numEligibleSlots, totalWeight)
}
if isFirst {
isFirst = false
} else if counter <= last {
return false, fmt.Errorf("%w: %d <= %d", errInvalidProofsOrder, counter, last)
}
last = counter
message, err := SerializeVRFMessage(beacon, epoch, nonce, counter)
if err != nil {
return false, err
}
vrfSig := proof.Sig
beaconStr := beacon.ShortString()
if !v.vrfVerifier.Verify(owned.NodeID, message, vrfSig) {
return false, fmt.Errorf("%w: beacon: %v, epoch: %v, counter: %v, vrfSig: %s",
errIncorrectVRFSig, beaconStr, epoch, counter, vrfSig,
)
}
eligibleLayer := CalcEligibleLayer(epoch, v.layersPerEpoch, vrfSig)
if ballot.Layer != eligibleLayer {
return false, fmt.Errorf("%w: ballot layer (%v), eligible layer (%v)",
errIncorrectLayerIndex, ballot.Layer, eligibleLayer)
}
}
v.logger.WithContext(ctx).With().Debug("ballot eligibility verified",
ballot.ID(),
ballot.Layer,
epoch,
beacon,
)
weightPer := fixed.DivUint64(atxWeight, uint64(numEligibleSlots))
v.beacons.ReportBeaconFromBallot(epoch, ballot, beacon, weightPer)
return true, nil
}