Add HeadGenesisValidatorRoot for DomainData (#5582)

* Provide getters

* Using it in DomainData

* Fixed test

* Tests

Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>

beacon-chain/blockchain/chain_info.go

@@ -43,6 +43,7 @@ type HeadFetcher interface {
 	HeadState(ctx context.Context) (*state.BeaconState, error)
 	HeadValidatorsIndices(epoch uint64) ([]uint64, error)
 	HeadSeed(epoch uint64) ([32]byte, error)
+	HeadGenesisValidatorRoot() [32]byte
 }
 
 // ForkFetcher retrieves the current fork information of the Ethereum beacon chain.
@@ -180,6 +181,15 @@ func (s *Service) HeadSeed(epoch uint64) ([32]byte, error) {
 	return helpers.Seed(s.headState(), epoch, params.BeaconConfig().DomainBeaconAttester)
 }
 
+// HeadGenesisValidatorRoot returns genesis validator root of the head state.
+func (s *Service) HeadGenesisValidatorRoot() [32]byte {
+	if !s.hasHeadState() {
+		return [32]byte{}
+	}
+
+	return s.headGenesisValidatorRoot()
+}
+
 // GenesisTime returns the genesis time of beacon chain.
 func (s *Service) GenesisTime() time.Time {
 	return s.genesisTime

beacon-chain/blockchain/chain_info_test.go

@@ -201,3 +201,20 @@ func TestCurrentFork_CanRetrieve(t *testing.T) {
 		t.Error("Received incorrect fork version")
 	}
 }
+
+func TestGenesisValidatorRoot_CanRetrieve(t *testing.T) {
+	// Should not panic if head state is nil.
+	c := &Service{}
+	if c.GenesisValidatorRoot() != [32]byte{} {
+		t.Error("Did not get correct genesis validator root")
+	}
+
+	s, err := state.InitializeFromProto(&pb.BeaconState{GenesisValidatorsRoot: []byte{'a'}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	c.head = &head{state: s}
+	if c.GenesisValidatorRoot() != [32]byte{'a'} {
+		t.Error("Did not get correct genesis validator root")
+	}
+}

beacon-chain/blockchain/head.go

@@ -202,6 +202,14 @@ func (s *Service) headState() *state.BeaconState {
 	return s.head.state.Copy()
 }
 
+// This returns the genesis validator root of the head state.
+func (s *Service) headGenesisValidatorRoot() [32]byte {
+	s.headLock.RLock()
+	defer s.headLock.RUnlock()
+
+	return bytesutil.ToBytes32(s.head.state.GenesisValidatorRoot())
+}
+
 // Returns true if head state exists.
 func (s *Service) hasHeadState() bool {
 	s.headLock.RLock()

beacon-chain/blockchain/testing/mock.go

@@ -245,3 +245,8 @@ func (ms *ChainService) ClearCachedStates() {}
 func (ms *ChainService) HasInitSyncBlock(root [32]byte) bool {
 	return false
 }
+
+// HeadGenesisValidatorRoot mocks HeadGenesisValidatorRoot method in chain service.
+func (ms *ChainService) HeadGenesisValidatorRoot() [32]byte {
+	return [32]byte{}
+}

beacon-chain/rpc/validator/server.go

@@ -131,11 +131,8 @@ func (vs *Server) ValidatorIndex(ctx context.Context, req *ethpb.ValidatorIndexR
 // DomainData fetches the current domain version information from the beacon state.
 func (vs *Server) DomainData(ctx context.Context, request *ethpb.DomainRequest) (*ethpb.DomainResponse, error) {
 	fork := vs.ForkFetcher.CurrentFork()
-	s, err := vs.HeadFetcher.HeadState(ctx)
-	if err != nil {
-		return nil, err
-	}
-	dv, err := helpers.Domain(fork, request.Epoch, bytesutil.ToBytes4(request.Domain), s.GenesisValidatorRoot())
+	headGenesisValidatorRoot := vs.HeadFetcher.HeadGenesisValidatorRoot()
+	dv, err := helpers.Domain(fork, request.Epoch, bytesutil.ToBytes4(request.Domain), headGenesisValidatorRoot[:])
 	if err != nil {
 		return nil, err
 	}