Ensure exits are not for an already exited validator (#4701)

* ensure exits are not for an already exited validator

beacon-chain/operations/voluntaryexits/BUILD.bazel

@@ -10,6 +10,7 @@ go_library(
     visibility = ["//beacon-chain:__subpackages__"],
     deps = [
         "//beacon-chain/core/helpers:go_default_library",
+        "//beacon-chain/state:go_default_library",
         "//shared/params:go_default_library",
         "@com_github_prysmaticlabs_ethereumapis//eth/v1alpha1:go_default_library",
     ],
@@ -21,6 +22,8 @@ go_test(
     srcs = ["service_test.go"],
     embed = [":go_default_library"],
     deps = [
+        "//beacon-chain/state:go_default_library",
+        "//proto/beacon/p2p/v1:go_default_library",
         "//shared/params:go_default_library",
         "@com_github_gogo_protobuf//proto:go_default_library",
         "@com_github_prysmaticlabs_ethereumapis//eth/v1alpha1:go_default_library",

beacon-chain/operations/voluntaryexits/service.go

@@ -7,6 +7,7 @@ import (
 
 	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
+	beaconstate "github.com/prysmaticlabs/prysm/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/shared/params"
 )
 
@@ -29,7 +30,7 @@ func NewPool() *Pool {
 
 // PendingExits returns exits that are ready for inclusion at the given slot. This method will not
 // return more than the block enforced MaxVoluntaryExits.
-func (p *Pool) PendingExits(slot uint64) []*ethpb.SignedVoluntaryExit {
+func (p *Pool) PendingExits(state *beaconstate.BeaconState, slot uint64) []*ethpb.SignedVoluntaryExit {
 	p.lock.RLock()
 	defer p.lock.RUnlock()
 	pending := make([]*ethpb.SignedVoluntaryExit, 0)
@@ -37,7 +38,9 @@ func (p *Pool) PendingExits(slot uint64) []*ethpb.SignedVoluntaryExit {
 		if e.Exit.Epoch > helpers.SlotToEpoch(slot) {
 			continue
 		}
-		pending = append(pending, e)
+		if v, err := state.ValidatorAtIndexReadOnly(e.Exit.ValidatorIndex); err == nil && v.ExitEpoch() == params.BeaconConfig().FarFutureEpoch {
+			pending = append(pending, e)
+		}
 	}
 	if len(pending) > int(params.BeaconConfig().MaxVoluntaryExits) {
 		pending = pending[:params.BeaconConfig().MaxVoluntaryExits]
@@ -47,7 +50,7 @@ func (p *Pool) PendingExits(slot uint64) []*ethpb.SignedVoluntaryExit {
 
 // InsertVoluntaryExit into the pool. This method is a no-op if the pending exit already exists,
 // has been included recently, or the validator is already exited.
-func (p *Pool) InsertVoluntaryExit(ctx context.Context, validators []*ethpb.Validator, exit *ethpb.SignedVoluntaryExit) {
+func (p *Pool) InsertVoluntaryExit(ctx context.Context, state *beaconstate.BeaconState, exit *ethpb.SignedVoluntaryExit) {
 	p.lock.Lock()
 	defer p.lock.Unlock()
 
@@ -57,7 +60,7 @@ func (p *Pool) InsertVoluntaryExit(ctx context.Context, validators []*ethpb.Vali
 	}
 
 	// Has the validator been exited already?
-	if len(validators) <= int(exit.Exit.ValidatorIndex) || validators[exit.Exit.ValidatorIndex].ExitEpoch != params.BeaconConfig().FarFutureEpoch {
+	if v, err := state.ValidatorAtIndexReadOnly(exit.Exit.ValidatorIndex); err != nil || v.ExitEpoch() != params.BeaconConfig().FarFutureEpoch {
 		return
 	}
 

beacon-chain/operations/voluntaryexits/service_test.go

@@ -7,6 +7,8 @@ import (
 
 	"github.com/gogo/protobuf/proto"
 	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
+	beaconstate "github.com/prysmaticlabs/prysm/beacon-chain/state"
+	p2ppb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
 	"github.com/prysmaticlabs/prysm/shared/params"
 )
 
@@ -211,7 +213,11 @@ func TestPool_InsertVoluntaryExit(t *testing.T) {
 				pending:  tt.fields.pending,
 				included: tt.fields.included,
 			}
-			p.InsertVoluntaryExit(ctx, validators, tt.args.exit)
+			s, err := beaconstate.InitializeFromProtoUnsafe(&p2ppb.BeaconState{Validators: validators})
+			if err != nil {
+				t.Fatal(err)
+			}
+			p.InsertVoluntaryExit(ctx, s, tt.args.exit)
 			if len(p.pending) != len(tt.want) {
 				t.Fatalf("Mismatched lengths of pending list. Got %d, wanted %d.", len(p.pending), len(tt.want))
 			}
@@ -444,7 +450,11 @@ func TestPool_PendingExits(t *testing.T) {
 			p := &Pool{
 				pending: tt.fields.pending,
 			}
-			if got := p.PendingExits(tt.args.slot); !reflect.DeepEqual(got, tt.want) {
+			s, err := beaconstate.InitializeFromProtoUnsafe(&p2ppb.BeaconState{Validators: []*ethpb.Validator{{ExitEpoch: params.BeaconConfig().FarFutureEpoch}}})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if got := p.PendingExits(s, tt.args.slot); !reflect.DeepEqual(got, tt.want) {
 				t.Errorf("PendingExits() = %v, want %v", got, tt.want)
 			}
 		})

beacon-chain/rpc/validator/exit.go

@@ -40,7 +40,7 @@ func (vs *Server) ProposeExit(ctx context.Context, req *ethpb.SignedVoluntaryExi
 		},
 	})
 
-	vs.ExitPool.InsertVoluntaryExit(ctx, s.Validators(), req)
+	vs.ExitPool.InsertVoluntaryExit(ctx, s, req)
 
 	return &ptypes.Empty{}, vs.P2P.Broadcast(ctx, req)
 }

beacon-chain/rpc/validator/proposer.go

@@ -63,6 +63,11 @@ func (vs *Server) GetBlock(ctx context.Context, req *ethpb.BlockRequest) (*ethpb
 
 	graffiti := bytesutil.ToBytes32(req.Graffiti)
 
+	head, err := vs.HeadFetcher.HeadState(ctx)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "Could not get head state %v", err)
+	}
+
 	blk := &ethpb.BeaconBlock{
 		Slot:       req.Slot,
 		ParentRoot: parentRoot[:],
@@ -75,7 +80,7 @@ func (vs *Server) GetBlock(ctx context.Context, req *ethpb.BlockRequest) (*ethpb
 			// TODO(2766): Implement rest of the retrievals for beacon block operations
 			ProposerSlashings: []*ethpb.ProposerSlashing{},
 			AttesterSlashings: []*ethpb.AttesterSlashing{},
-			VoluntaryExits:    vs.ExitPool.PendingExits(req.Slot),
+			VoluntaryExits:    vs.ExitPool.PendingExits(head, req.Slot),
 			Graffiti:          graffiti[:],
 		},
 	}

beacon-chain/sync/subscriber_handlers.go

@@ -12,7 +12,7 @@ func (r *Service) voluntaryExitSubscriber(ctx context.Context, msg proto.Message
 	if err != nil {
 		return err
 	}
-	r.exitPool.InsertVoluntaryExit(ctx, s.Validators(), msg.(*ethpb.SignedVoluntaryExit))
+	r.exitPool.InsertVoluntaryExit(ctx, s, msg.(*ethpb.SignedVoluntaryExit))
 	return nil
 }