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exit.go
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exit.go
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package blocks
import (
"context"
"fmt"
"github.com/pkg/errors"
ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
v "github.com/prysmaticlabs/prysm/beacon-chain/core/validators"
stateTrie "github.com/prysmaticlabs/prysm/beacon-chain/state"
pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
"github.com/prysmaticlabs/prysm/shared/params"
)
// ValidatorAlreadyExitedMsg defines a message saying that a validator has already exited.
var ValidatorAlreadyExitedMsg = "has already submitted an exit, which will take place at epoch"
// ValidatorCannotExitYetMsg defines a message saying that a validator cannot exit
// because it has not been active long enough.
var ValidatorCannotExitYetMsg = "validator has not been active long enough to exit"
// ProcessVoluntaryExits is one of the operations performed
// on each processed beacon block to determine which validators
// should exit the state's validator registry.
//
// Spec pseudocode definition:
// def process_voluntary_exit(state: BeaconState, exit: VoluntaryExit) -> None:
// """
// Process ``VoluntaryExit`` operation.
// """
// validator = state.validator_registry[exit.validator_index]
// # Verify the validator is active
// assert is_active_validator(validator, get_current_epoch(state))
// # Verify the validator has not yet exited
// assert validator.exit_epoch == FAR_FUTURE_EPOCH
// # Exits must specify an epoch when they become valid; they are not valid before then
// assert get_current_epoch(state) >= exit.epoch
// # Verify the validator has been active long enough
// assert get_current_epoch(state) >= validator.activation_epoch + PERSISTENT_COMMITTEE_PERIOD
// # Verify signature
// domain = get_domain(state, DOMAIN_VOLUNTARY_EXIT, exit.epoch)
// assert bls_verify(validator.pubkey, signing_root(exit), exit.signature, domain)
// # Initiate exit
// initiate_validator_exit(state, exit.validator_index)
func ProcessVoluntaryExits(
_ context.Context,
beaconState *stateTrie.BeaconState,
b *ethpb.SignedBeaconBlock,
) (*stateTrie.BeaconState, error) {
if b.Block == nil || b.Block.Body == nil {
return nil, errors.New("block and block body can't be nil")
}
body := b.Block.Body
exits := body.VoluntaryExits
for idx, exit := range exits {
if exit == nil || exit.Exit == nil {
return nil, errors.New("nil voluntary exit in block body")
}
val, err := beaconState.ValidatorAtIndexReadOnly(exit.Exit.ValidatorIndex)
if err != nil {
return nil, err
}
if err := VerifyExitAndSignature(val, beaconState.Slot(), beaconState.Fork(), exit, beaconState.GenesisValidatorRoot()); err != nil {
return nil, errors.Wrapf(err, "could not verify exit %d", idx)
}
beaconState, err = v.InitiateValidatorExit(beaconState, exit.Exit.ValidatorIndex)
if err != nil {
return nil, err
}
}
return beaconState, nil
}
// ProcessVoluntaryExitsNoVerifySignature processes all the voluntary exits in
// a block body, without verifying their BLS signatures.
// This function is here to satisfy fuzz tests.
func ProcessVoluntaryExitsNoVerifySignature(
beaconState *stateTrie.BeaconState,
body *ethpb.BeaconBlockBody,
) (*stateTrie.BeaconState, error) {
exits := body.VoluntaryExits
for idx, exit := range exits {
if exit == nil || exit.Exit == nil {
return nil, errors.New("nil exit")
}
val, err := beaconState.ValidatorAtIndexReadOnly(exit.Exit.ValidatorIndex)
if err != nil {
return nil, err
}
if err := verifyExitConditions(val, beaconState.Slot(), exit.Exit); err != nil {
return nil, err
}
// Validate that fork and genesis root are valid.
_, err = helpers.Domain(beaconState.Fork(), exit.Exit.Epoch, params.BeaconConfig().DomainVoluntaryExit, beaconState.GenesisValidatorRoot())
if err != nil {
return nil, err
}
beaconState, err = v.InitiateValidatorExit(beaconState, exit.Exit.ValidatorIndex)
if err != nil {
return nil, errors.Wrapf(err, "failed to process voluntary exit at index %d", idx)
}
}
return beaconState, nil
}
// VerifyExitAndSignature implements the spec defined validation for voluntary exits.
//
// Spec pseudocode definition:
// def process_voluntary_exit(state: BeaconState, exit: VoluntaryExit) -> None:
// """
// Process ``VoluntaryExit`` operation.
// """
// validator = state.validator_registry[exit.validator_index]
// # Verify the validator is active
// assert is_active_validator(validator, get_current_epoch(state))
// # Verify the validator has not yet exited
// assert validator.exit_epoch == FAR_FUTURE_EPOCH
// # Exits must specify an epoch when they become valid; they are not valid before then
// assert get_current_epoch(state) >= exit.epoch
// # Verify the validator has been active long enough
// assert get_current_epoch(state) >= validator.activation_epoch + PERSISTENT_COMMITTEE_PERIOD
// # Verify signature
// domain = get_domain(state, DOMAIN_VOLUNTARY_EXIT, exit.epoch)
// assert bls_verify(validator.pubkey, signing_root(exit), exit.signature, domain)
func VerifyExitAndSignature(validator stateTrie.ReadOnlyValidator, currentSlot uint64, fork *pb.Fork, signed *ethpb.SignedVoluntaryExit, genesisRoot []byte) error {
if signed == nil || signed.Exit == nil {
return errors.New("nil exit")
}
exit := signed.Exit
if err := verifyExitConditions(validator, currentSlot, exit); err != nil {
return err
}
domain, err := helpers.Domain(fork, exit.Epoch, params.BeaconConfig().DomainVoluntaryExit, genesisRoot)
if err != nil {
return err
}
valPubKey := validator.PublicKey()
if err := helpers.VerifySigningRoot(exit, valPubKey[:], signed.Signature, domain); err != nil {
return helpers.ErrSigFailedToVerify
}
return nil
}
// verifyExitConditions implements the spec defined validation for voluntary exits(excluding signatures).
//
// Spec pseudocode definition:
// def process_voluntary_exit(state: BeaconState, exit: VoluntaryExit) -> None:
// """
// Process ``VoluntaryExit`` operation.
// """
// validator = state.validator_registry[exit.validator_index]
// # Verify the validator is active
// assert is_active_validator(validator, get_current_epoch(state))
// # Verify the validator has not yet exited
// assert validator.exit_epoch == FAR_FUTURE_EPOCH
// # Exits must specify an epoch when they become valid; they are not valid before then
// assert get_current_epoch(state) >= exit.epoch
// # Verify the validator has been active long enough
// assert get_current_epoch(state) >= validator.activation_epoch + SHARD_COMMITTEE_PERIOD
func verifyExitConditions(validator stateTrie.ReadOnlyValidator, currentSlot uint64, exit *ethpb.VoluntaryExit) error {
currentEpoch := helpers.SlotToEpoch(currentSlot)
// Verify the validator is active.
if !helpers.IsActiveValidatorUsingTrie(validator, currentEpoch) {
return errors.New("non-active validator cannot exit")
}
// Verify the validator has not yet submitted an exit.
if validator.ExitEpoch() != params.BeaconConfig().FarFutureEpoch {
return fmt.Errorf("validator with index %d %s: %v", exit.ValidatorIndex, ValidatorAlreadyExitedMsg, validator.ExitEpoch())
}
// Exits must specify an epoch when they become valid; they are not valid before then.
if currentEpoch < exit.Epoch {
return fmt.Errorf("expected current epoch >= exit epoch, received %d < %d", currentEpoch, exit.Epoch)
}
// Verify the validator has been active long enough.
if currentEpoch < validator.ActivationEpoch()+params.BeaconConfig().ShardCommitteePeriod {
return fmt.Errorf(
"%s: %d epochs vs required %d epochs",
ValidatorCannotExitYetMsg,
currentEpoch,
validator.ActivationEpoch()+params.BeaconConfig().ShardCommitteePeriod,
)
}
return nil
}