Electra: EIP-7251 Update process_voluntary_exit (#14176)

* Electra: EIP-7251 Update `process_voluntary_exit`

* Add unit test for VerifyExitAndSignature EIP-7251

* @potuz peer feedback

beacon-chain/core/blocks/exit.go

@@ -98,6 +98,8 @@ func ProcessVoluntaryExits(
 //	 assert get_current_epoch(state) >= voluntary_exit.epoch
 //	 # Verify the validator has been active long enough
 //	 assert get_current_epoch(state) >= validator.activation_epoch + SHARD_COMMITTEE_PERIOD
+//	 # Only exit validator if it has no pending withdrawals in the queue
+//	 assert get_pending_balance_to_withdraw(state, voluntary_exit.validator_index) == 0  # [New in Electra:EIP7251]
 //	 # Verify signature
 //	 domain = get_domain(state, DOMAIN_VOLUNTARY_EXIT, voluntary_exit.epoch)
 //	 signing_root = compute_signing_root(voluntary_exit, domain)
@@ -113,7 +115,6 @@ func VerifyExitAndSignature(
 		return errors.New("nil exit")
 	}
 
-	currentSlot := state.Slot()
 	fork := state.Fork()
 	genesisRoot := state.GenesisValidatorsRoot()
 
@@ -128,7 +129,7 @@ func VerifyExitAndSignature(
 	}
 
 	exit := signed.Exit
-	if err := verifyExitConditions(validator, currentSlot, exit); err != nil {
+	if err := verifyExitConditions(state, validator, exit); err != nil {
 		return err
 	}
 	domain, err := signing.Domain(fork, exit.Epoch, params.BeaconConfig().DomainVoluntaryExit, genesisRoot)
@@ -157,14 +158,16 @@ func VerifyExitAndSignature(
 //	 assert get_current_epoch(state) >= voluntary_exit.epoch
 //	 # Verify the validator has been active long enough
 //	 assert get_current_epoch(state) >= validator.activation_epoch + SHARD_COMMITTEE_PERIOD
+//	 # Only exit validator if it has no pending withdrawals in the queue
+//	 assert get_pending_balance_to_withdraw(state, voluntary_exit.validator_index) == 0  # [New in Electra:EIP7251]
 //	 # Verify signature
 //	 domain = get_domain(state, DOMAIN_VOLUNTARY_EXIT, voluntary_exit.epoch)
 //	 signing_root = compute_signing_root(voluntary_exit, domain)
 //	 assert bls.Verify(validator.pubkey, signing_root, signed_voluntary_exit.signature)
 //	 # Initiate exit
 //	 initiate_validator_exit(state, voluntary_exit.validator_index)
-func verifyExitConditions(validator state.ReadOnlyValidator, currentSlot primitives.Slot, exit *ethpb.VoluntaryExit) error {
-	currentEpoch := slots.ToEpoch(currentSlot)
+func verifyExitConditions(st state.ReadOnlyBeaconState, validator state.ReadOnlyValidator, exit *ethpb.VoluntaryExit) error {
+	currentEpoch := slots.ToEpoch(st.Slot())
 	// Verify the validator is active.
 	if !helpers.IsActiveValidatorUsingTrie(validator, currentEpoch) {
 		return errors.New("non-active validator cannot exit")
@@ -187,5 +190,17 @@ func verifyExitConditions(validator state.ReadOnlyValidator, currentSlot primiti
 			validator.ActivationEpoch()+params.BeaconConfig().ShardCommitteePeriod,
 		)
 	}
+
+	if st.Version() >= version.Electra {
+		// Only exit validator if it has no pending withdrawals in the queue.
+		pbw, err := st.PendingBalanceToWithdraw(exit.ValidatorIndex)
+		if err != nil {
+			return fmt.Errorf("unable to retrieve pending balance to withdraw for validator %d: %w", exit.ValidatorIndex, err)
+		}
+		if pbw != 0 {
+			return fmt.Errorf("validator %d must have no pending balance to withdraw, got %d pending balance to withdraw", exit.ValidatorIndex, pbw)
+		}
+	}
+
 	return nil
 }

beacon-chain/core/blocks/exit_test.go

@@ -135,6 +135,11 @@ func TestProcessVoluntaryExits_AppliesCorrectStatus(t *testing.T) {
 }
 
 func TestVerifyExitAndSignature(t *testing.T) {
+	// Remove after electra fork epoch is defined.
+	cfg := params.BeaconConfig()
+	cfg.ElectraForkEpoch = cfg.DenebForkEpoch * 2
+	params.SetActiveTestCleanup(t, cfg)
+	// End remove section.
 	denebSlot, err := slots.EpochStart(params.BeaconConfig().DenebForkEpoch)
 	require.NoError(t, err)
 	tests := []struct {
@@ -167,7 +172,7 @@ func TestVerifyExitAndSignature(t *testing.T) {
 			wantErr: "nil exit",
 		},
 		{
-			name: "Happy Path",
+			name: "Happy Path phase0",
 			setup: func() (*ethpb.Validator, *ethpb.SignedVoluntaryExit, state.ReadOnlyBeaconState, error) {
 				fork := &ethpb.Fork{
 					PreviousVersion: params.BeaconConfig().GenesisForkVersion,
@@ -275,6 +280,52 @@ func TestVerifyExitAndSignature(t *testing.T) {
 				return validator, signedExit, bs, nil
 			},
 		},
+		{
+			name: "EIP-7251 - pending balance to withdraw must be zero",
+			setup: func() (*ethpb.Validator, *ethpb.SignedVoluntaryExit, state.ReadOnlyBeaconState, error) {
+				fork := &ethpb.Fork{
+					PreviousVersion: params.BeaconConfig().DenebForkVersion,
+					CurrentVersion:  params.BeaconConfig().ElectraForkVersion,
+					Epoch:           params.BeaconConfig().ElectraForkEpoch,
+				}
+				signedExit := &ethpb.SignedVoluntaryExit{
+					Exit: &ethpb.VoluntaryExit{
+						Epoch:          params.BeaconConfig().DenebForkEpoch + 1,
+						ValidatorIndex: 0,
+					},
+				}
+				electraSlot, err := slots.EpochStart(params.BeaconConfig().ElectraForkEpoch)
+				require.NoError(t, err)
+				bs, keys := util.DeterministicGenesisState(t, 1)
+				bs, err = state_native.InitializeFromProtoUnsafeElectra(&ethpb.BeaconStateElectra{
+					GenesisValidatorsRoot: bs.GenesisValidatorsRoot(),
+					Fork:                  fork,
+					Slot:                  electraSlot,
+					Validators:            bs.Validators(),
+				})
+				if err != nil {
+					return nil, nil, nil, err
+				}
+				validator := bs.Validators()[0]
+				validator.ActivationEpoch = 1
+				err = bs.UpdateValidatorAtIndex(0, validator)
+				require.NoError(t, err)
+				sb, err := signing.ComputeDomainAndSign(bs, signedExit.Exit.Epoch, signedExit.Exit, params.BeaconConfig().DomainVoluntaryExit, keys[0])
+				require.NoError(t, err)
+				sig, err := bls.SignatureFromBytes(sb)
+				require.NoError(t, err)
+				signedExit.Signature = sig.Marshal()
+
+				// Give validator a pending balance to withdraw.
+				require.NoError(t, bs.AppendPendingPartialWithdrawal(&ethpb.PendingPartialWithdrawal{
+					Index:  0,
+					Amount: 500,
+				}))
+
+				return validator, signedExit, bs, nil
+			},
+			wantErr: "validator 0 must have no pending balance to withdraw",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

testing/spectest/mainnet/electra/operations/voluntary_exit_test.go

@@ -7,6 +7,5 @@ import (
 )
 
 func TestMainnet_Electra_Operations_VoluntaryExit(t *testing.T) {
-	t.Skip("TODO: Electra")
 	operations.RunVoluntaryExitTest(t, "mainnet")
 }

testing/spectest/minimal/electra/operations/voluntary_exit_test.go

@@ -7,6 +7,5 @@ import (
 )
 
 func TestMinimal_Electra_Operations_VoluntaryExit(t *testing.T) {
-	t.Skip("TODO: Electra")
 	operations.RunVoluntaryExitTest(t, "minimal")
 }