Add SSZ support for light client updates by range API (#15082)

* create ssz payload

* remove unused function

* remove access to state

* gazelle fix

* fix ssz size for electra finality update

* fix fork digest version problem

* fix chunk size

* fix fork version

* fix fork version

* add tests

* add changelog entry

* add PR link in changelog entry

* fix lint error

* Update beacon-chain/rpc/eth/light-client/handlers.go

Co-authored-by: Preston Van Loon <pvanloon@offchainlabs.com>

* check for context error

* send response in chunks

* remove content disposition header

---------

Co-authored-by: Preston Van Loon <pvanloon@offchainlabs.com>

beacon-chain/rpc/eth/light-client/BUILD.bazel

@@ -13,18 +13,22 @@ go_library(
         "//api/server/structs:go_default_library",
         "//beacon-chain/blockchain:go_default_library",
         "//beacon-chain/core/light-client:go_default_library",
+        "//beacon-chain/core/signing:go_default_library",
         "//beacon-chain/db:go_default_library",
         "//beacon-chain/rpc/eth/shared:go_default_library",
         "//beacon-chain/rpc/lookup:go_default_library",
         "//config/features:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/interfaces:go_default_library",
+        "//encoding/bytesutil:go_default_library",
         "//monitoring/tracing/trace:go_default_library",
+        "//network/forks:go_default_library",
         "//network/httputil:go_default_library",
         "//runtime/version:go_default_library",
+        "//time/slots:go_default_library",
         "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
         "@com_github_pkg_errors//:go_default_library",
-        "@com_github_wealdtech_go_bytesutil//:go_default_library",
+        "@com_github_prysmaticlabs_fastssz//:go_default_library",
     ],
 )
 
@@ -56,5 +60,6 @@ go_test(
         "//testing/require:go_default_library",
         "//testing/util:go_default_library",
         "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
+        "@com_github_prysmaticlabs_fastssz//:go_default_library",
     ],
 )

beacon-chain/rpc/eth/light-client/handlers.go

@@ -8,17 +8,21 @@ import (
 
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/pkg/errors"
+	ssz "github.com/prysmaticlabs/fastssz"
 	"github.com/prysmaticlabs/prysm/v5/api"
 	"github.com/prysmaticlabs/prysm/v5/api/server/structs"
 	lightclient "github.com/prysmaticlabs/prysm/v5/beacon-chain/core/light-client"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/signing"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/rpc/eth/shared"
 	"github.com/prysmaticlabs/prysm/v5/config/features"
 	"github.com/prysmaticlabs/prysm/v5/config/params"
 	"github.com/prysmaticlabs/prysm/v5/consensus-types/interfaces"
+	"github.com/prysmaticlabs/prysm/v5/encoding/bytesutil"
 	"github.com/prysmaticlabs/prysm/v5/monitoring/tracing/trace"
+	"github.com/prysmaticlabs/prysm/v5/network/forks"
 	"github.com/prysmaticlabs/prysm/v5/network/httputil"
 	"github.com/prysmaticlabs/prysm/v5/runtime/version"
-	"github.com/wealdtech/go-bytesutil"
+	"github.com/prysmaticlabs/prysm/v5/time/slots"
 )
 
 // GetLightClientBootstrap - implements https://github.com/ethereum/beacon-APIs/blob/263f4ed6c263c967f13279c7a9f5629b51c5fc55/apis/beacon/light_client/bootstrap.yaml
@@ -111,9 +115,59 @@ func (s *Server) GetLightClientUpdatesByRange(w http.ResponseWriter, req *http.R
 		return
 	}
 
+	if httputil.RespondWithSsz(req) {
+		w.Header().Set("Content-Type", "application/octet-stream")
+
+		for i := startPeriod; i <= endPeriod; i++ {
+			if ctx.Err() != nil {
+				httputil.HandleError(w, "Context error: "+ctx.Err().Error(), http.StatusInternalServerError)
+			}
+
+			update, ok := updatesMap[i]
+			if !ok {
+				// Only return the first contiguous range of updates
+				break
+			}
+
+			updateSlot := update.AttestedHeader().Beacon().Slot
+			updateEpoch := slots.ToEpoch(updateSlot)
+			updateFork, err := forks.Fork(updateEpoch)
+			if err != nil {
+				httputil.HandleError(w, "Could not get fork Version: "+err.Error(), http.StatusInternalServerError)
+				return
+			}
+
+			forkDigest, err := signing.ComputeForkDigest(updateFork.CurrentVersion, params.BeaconConfig().GenesisValidatorsRoot[:])
+			if err != nil {
+				httputil.HandleError(w, "Could not compute fork digest: "+err.Error(), http.StatusInternalServerError)
+				return
+			}
+			updateSSZ, err := update.MarshalSSZ()
+			if err != nil {
+				httputil.HandleError(w, "Could not marshal update to SSZ: "+err.Error(), http.StatusInternalServerError)
+				return
+			}
+
+			var chunkLength []byte
+			chunkLength = ssz.MarshalUint64(chunkLength, uint64(len(updateSSZ)+4))
+			if _, err := w.Write(chunkLength); err != nil {
+				httputil.HandleError(w, "Could not write chunk length: "+err.Error(), http.StatusInternalServerError)
+			}
+			if _, err := w.Write(forkDigest[:]); err != nil {
+				httputil.HandleError(w, "Could not write fork digest: "+err.Error(), http.StatusInternalServerError)
+			}
+			if _, err := w.Write(updateSSZ); err != nil {
+				httputil.HandleError(w, "Could not write update SSZ: "+err.Error(), http.StatusInternalServerError)
+			}
+		}
+	} else {
 		updates := make([]*structs.LightClientUpdateResponse, 0, len(updatesMap))
 
 		for i := startPeriod; i <= endPeriod; i++ {
+			if ctx.Err() != nil {
+				httputil.HandleError(w, "Context error: "+ctx.Err().Error(), http.StatusInternalServerError)
+			}
+
 			update, ok := updatesMap[i]
 			if !ok {
 				// Only return the first contiguous range of updates
@@ -131,8 +185,10 @@ func (s *Server) GetLightClientUpdatesByRange(w http.ResponseWriter, req *http.R
 			}
 			updates = append(updates, updateResponse)
 		}
+
 		httputil.WriteJson(w, updates)
 	}
+}
 
 // GetLightClientFinalityUpdate - implements https://github.com/ethereum/beacon-APIs/blob/263f4ed6c263c967f13279c7a9f5629b51c5fc55/apis/beacon/light_client/finality_update.yaml
 func (s *Server) GetLightClientFinalityUpdate(w http.ResponseWriter, req *http.Request) {

beacon-chain/rpc/eth/light-client/handlers_test.go

@@ -12,6 +12,7 @@ import (
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common/hexutil"
+	ssz "github.com/prysmaticlabs/fastssz"
 	"github.com/prysmaticlabs/prysm/v5/api/server/structs"
 	mock "github.com/prysmaticlabs/prysm/v5/beacon-chain/blockchain/testing"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/helpers"
@@ -511,6 +512,44 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 		require.DeepEqual(t, updateJson, resp.Updates[0].Data)
 	})
 
+	t.Run("altair ssz", func(t *testing.T) {
+		slot := primitives.Slot(config.AltairForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
+
+		st, err := util.NewBeaconStateAltair()
+		require.NoError(t, err)
+		err = st.SetSlot(slot)
+		require.NoError(t, err)
+
+		db := dbtesting.SetupDB(t)
+
+		updatePeriod := uint64(slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch)))
+
+		update, err := createUpdate(t, version.Altair)
+		require.NoError(t, err)
+		err = db.SaveLightClientUpdate(ctx, updatePeriod, update)
+		require.NoError(t, err)
+
+		mockChainService := &mock.ChainService{State: st}
+		s := &Server{
+			HeadFetcher: mockChainService,
+			BeaconDB:    db,
+		}
+		startPeriod := slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+		url := fmt.Sprintf("http://foo.com/?count=1&start_period=%d", startPeriod)
+		request := httptest.NewRequest("GET", url, nil)
+		request.Header.Add("Accept", "application/octet-stream")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetLightClientUpdatesByRange(writer, request)
+
+		require.Equal(t, http.StatusOK, writer.Code)
+		var resp pb.LightClientUpdateAltair
+		err = resp.UnmarshalSSZ(writer.Body.Bytes()[12:]) // skip the length and fork digest prefixes
+		require.NoError(t, err)
+		require.DeepEqual(t, resp.AttestedHeader, update.AttestedHeader().Proto())
+	})
+
 	t.Run("capella", func(t *testing.T) {
 		slot := primitives.Slot(config.CapellaForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
 
@@ -553,6 +592,45 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 		require.DeepEqual(t, updateJson, resp.Updates[0].Data)
 	})
 
+	t.Run("capella ssz", func(t *testing.T) {
+		slot := primitives.Slot(config.CapellaForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
+
+		st, err := util.NewBeaconStateCapella()
+		require.NoError(t, err)
+		err = st.SetSlot(slot)
+		require.NoError(t, err)
+
+		db := dbtesting.SetupDB(t)
+
+		updatePeriod := uint64(slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch)))
+
+		update, err := createUpdate(t, version.Capella)
+		require.NoError(t, err)
+
+		err = db.SaveLightClientUpdate(ctx, updatePeriod, update)
+		require.NoError(t, err)
+
+		mockChainService := &mock.ChainService{State: st}
+		s := &Server{
+			HeadFetcher: mockChainService,
+			BeaconDB:    db,
+		}
+		startPeriod := slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+		url := fmt.Sprintf("http://foo.com/?count=1&start_period=%d", startPeriod)
+		request := httptest.NewRequest("GET", url, nil)
+		request.Header.Add("Accept", "application/octet-stream")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetLightClientUpdatesByRange(writer, request)
+
+		require.Equal(t, http.StatusOK, writer.Code)
+		var resp pb.LightClientUpdateCapella
+		err = resp.UnmarshalSSZ(writer.Body.Bytes()[12:]) // skip the length and fork digest prefixes
+		require.NoError(t, err)
+		require.DeepEqual(t, resp.AttestedHeader, update.AttestedHeader().Proto())
+	})
+
 	t.Run("deneb", func(t *testing.T) {
 		slot := primitives.Slot(config.DenebForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
 
@@ -594,6 +672,44 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 		require.DeepEqual(t, updateJson, resp.Updates[0].Data)
 	})
 
+	t.Run("deneb ssz", func(t *testing.T) {
+		slot := primitives.Slot(config.DenebForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
+
+		st, err := util.NewBeaconStateDeneb()
+		require.NoError(t, err)
+		err = st.SetSlot(slot)
+		require.NoError(t, err)
+
+		db := dbtesting.SetupDB(t)
+
+		updatePeriod := uint64(slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch)))
+
+		update, err := createUpdate(t, version.Deneb)
+		require.NoError(t, err)
+		err = db.SaveLightClientUpdate(ctx, updatePeriod, update)
+		require.NoError(t, err)
+
+		mockChainService := &mock.ChainService{State: st}
+		s := &Server{
+			HeadFetcher: mockChainService,
+			BeaconDB:    db,
+		}
+		startPeriod := slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+		url := fmt.Sprintf("http://foo.com/?count=1&start_period=%d", startPeriod)
+		request := httptest.NewRequest("GET", url, nil)
+		request.Header.Add("Accept", "application/octet-stream")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetLightClientUpdatesByRange(writer, request)
+
+		require.Equal(t, http.StatusOK, writer.Code)
+		var resp pb.LightClientUpdateDeneb
+		err = resp.UnmarshalSSZ(writer.Body.Bytes()[12:]) // skip the length and fork digest prefixes
+		require.NoError(t, err)
+		require.DeepEqual(t, resp.AttestedHeader, update.AttestedHeader().Proto())
+	})
+
 	t.Run("altair Multiple", func(t *testing.T) {
 		slot := primitives.Slot(config.AltairForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
 
@@ -646,6 +762,60 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 		}
 	})
 
+	t.Run("altair Multiple ssz", func(t *testing.T) {
+		slot := primitives.Slot(config.AltairForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
+
+		st, err := util.NewBeaconStateAltair()
+		require.NoError(t, err)
+		headSlot := slot.Add(2 * uint64(config.SlotsPerEpoch) * uint64(config.EpochsPerSyncCommitteePeriod)) // 2 periods
+		err = st.SetSlot(headSlot)
+		require.NoError(t, err)
+
+		db := dbtesting.SetupDB(t)
+
+		updatePeriod := slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+
+		updates := make([]interfaces.LightClientUpdate, 0)
+		for i := 1; i <= 2; i++ {
+			update, err := createUpdate(t, version.Altair)
+			require.NoError(t, err)
+			updates = append(updates, update)
+		}
+
+		for _, update := range updates {
+			err := db.SaveLightClientUpdate(ctx, uint64(updatePeriod), update)
+			require.NoError(t, err)
+			updatePeriod++
+		}
+
+		mockChainService := &mock.ChainService{State: st}
+		s := &Server{
+			HeadFetcher: mockChainService,
+			BeaconDB:    db,
+		}
+		startPeriod := slot.Sub(1).Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+		url := fmt.Sprintf("http://foo.com/?count=100&start_period=%d", startPeriod)
+		request := httptest.NewRequest("GET", url, nil)
+		request.Header.Add("Accept", "application/octet-stream")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetLightClientUpdatesByRange(writer, request)
+
+		require.Equal(t, http.StatusOK, writer.Code)
+
+		offset := 0
+		for i := 0; offset < writer.Body.Len(); i++ {
+			updateLen := int(ssz.UnmarshallUint64(writer.Body.Bytes()[offset:offset+8]) - 4)
+			offset += 12
+			var resp pb.LightClientUpdateAltair
+			err = resp.UnmarshalSSZ(writer.Body.Bytes()[offset : offset+updateLen])
+			require.NoError(t, err)
+			require.DeepEqual(t, resp.AttestedHeader, updates[i].AttestedHeader().Proto())
+			offset += updateLen
+		}
+	})
+
 	t.Run("capella Multiple", func(t *testing.T) {
 		slot := primitives.Slot(config.CapellaForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
 
@@ -698,6 +868,60 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 		}
 	})
 
+	t.Run("capella Multiple ssz", func(t *testing.T) {
+		slot := primitives.Slot(config.CapellaForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
+
+		st, err := util.NewBeaconStateAltair()
+		require.NoError(t, err)
+		headSlot := slot.Add(2 * uint64(config.SlotsPerEpoch) * uint64(config.EpochsPerSyncCommitteePeriod)) // 2 periods
+		err = st.SetSlot(headSlot)
+		require.NoError(t, err)
+
+		db := dbtesting.SetupDB(t)
+
+		updatePeriod := slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+
+		updates := make([]interfaces.LightClientUpdate, 0)
+		for i := 0; i < 2; i++ {
+			update, err := createUpdate(t, version.Capella)
+			require.NoError(t, err)
+			updates = append(updates, update)
+		}
+
+		for _, update := range updates {
+			err := db.SaveLightClientUpdate(ctx, uint64(updatePeriod), update)
+			require.NoError(t, err)
+			updatePeriod++
+		}
+
+		mockChainService := &mock.ChainService{State: st}
+		s := &Server{
+			HeadFetcher: mockChainService,
+			BeaconDB:    db,
+		}
+		startPeriod := slot.Sub(1).Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+		url := fmt.Sprintf("http://foo.com/?count=100&start_period=%d", startPeriod)
+		request := httptest.NewRequest("GET", url, nil)
+		request.Header.Add("Accept", "application/octet-stream")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetLightClientUpdatesByRange(writer, request)
+
+		require.Equal(t, http.StatusOK, writer.Code)
+
+		offset := 0
+		for i := 0; offset < writer.Body.Len(); i++ {
+			updateLen := int(ssz.UnmarshallUint64(writer.Body.Bytes()[offset:offset+8]) - 4)
+			offset += 12
+			var resp pb.LightClientUpdateCapella
+			err = resp.UnmarshalSSZ(writer.Body.Bytes()[offset : offset+updateLen])
+			require.NoError(t, err)
+			require.DeepEqual(t, resp.AttestedHeader, updates[i].AttestedHeader().Proto())
+			offset += updateLen
+		}
+	})
+
 	t.Run("deneb Multiple", func(t *testing.T) {
 		slot := primitives.Slot(config.DenebForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
 
@@ -749,6 +973,59 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 		}
 	})
 
+	t.Run("deneb Multiple", func(t *testing.T) {
+		slot := primitives.Slot(config.DenebForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
+
+		st, err := util.NewBeaconStateAltair()
+		require.NoError(t, err)
+		headSlot := slot.Add(2 * uint64(config.SlotsPerEpoch) * uint64(config.EpochsPerSyncCommitteePeriod))
+		err = st.SetSlot(headSlot)
+		require.NoError(t, err)
+
+		db := dbtesting.SetupDB(t)
+
+		updatePeriod := slot.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+
+		updates := make([]interfaces.LightClientUpdate, 0)
+		for i := 0; i < 2; i++ {
+			update, err := createUpdate(t, version.Deneb)
+			require.NoError(t, err)
+			updates = append(updates, update)
+		}
+
+		for _, update := range updates {
+			err := db.SaveLightClientUpdate(ctx, uint64(updatePeriod), update)
+			require.NoError(t, err)
+			updatePeriod++
+		}
+		mockChainService := &mock.ChainService{State: st}
+		s := &Server{
+			HeadFetcher: mockChainService,
+			BeaconDB:    db,
+		}
+		startPeriod := slot.Sub(1).Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+		url := fmt.Sprintf("http://foo.com/?count=100&start_period=%d", startPeriod)
+		request := httptest.NewRequest("GET", url, nil)
+		request.Header.Add("Accept", "application/octet-stream")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetLightClientUpdatesByRange(writer, request)
+
+		require.Equal(t, http.StatusOK, writer.Code)
+
+		offset := 0
+		for i := 0; offset < writer.Body.Len(); i++ {
+			updateLen := int(ssz.UnmarshallUint64(writer.Body.Bytes()[offset:offset+8]) - 4)
+			offset += 12
+			var resp pb.LightClientUpdateDeneb
+			err = resp.UnmarshalSSZ(writer.Body.Bytes()[offset : offset+updateLen])
+			require.NoError(t, err)
+			require.DeepEqual(t, resp.AttestedHeader, updates[i].AttestedHeader().Proto())
+			offset += updateLen
+		}
+	})
+
 	t.Run("multiple forks - altair, capella", func(t *testing.T) {
 		slotCapella := primitives.Slot(config.CapellaForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
 		slotAltair := primitives.Slot(config.AltairForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
@@ -809,6 +1086,68 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 		}
 	})
 
+	t.Run("multiple forks - altair, capella - ssz", func(t *testing.T) {
+		slotCapella := primitives.Slot(config.CapellaForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
+		slotAltair := primitives.Slot(config.AltairForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
+
+		st, err := util.NewBeaconStateAltair()
+		require.NoError(t, err)
+		headSlot := slotCapella.Add(1)
+		err = st.SetSlot(headSlot)
+		require.NoError(t, err)
+
+		db := dbtesting.SetupDB(t)
+
+		updates := make([]interfaces.LightClientUpdate, 2)
+
+		updatePeriod := slotAltair.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+
+		updates[0], err = createUpdate(t, version.Altair)
+		require.NoError(t, err)
+
+		err = db.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[0])
+		require.NoError(t, err)
+
+		updatePeriod = slotCapella.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+
+		updates[1], err = createUpdate(t, version.Capella)
+		require.NoError(t, err)
+
+		err = db.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[1])
+		require.NoError(t, err)
+
+		mockChainService := &mock.ChainService{State: st}
+		s := &Server{
+			HeadFetcher: mockChainService,
+			BeaconDB:    db,
+		}
+		startPeriod := 0
+		url := fmt.Sprintf("http://foo.com/?count=100&start_period=%d", startPeriod)
+		request := httptest.NewRequest("GET", url, nil)
+		request.Header.Add("Accept", "application/octet-stream")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetLightClientUpdatesByRange(writer, request)
+
+		require.Equal(t, http.StatusOK, writer.Code)
+
+		offset := 0
+		updateLen := int(ssz.UnmarshallUint64(writer.Body.Bytes()[offset:offset+8]) - 4)
+		offset += 12
+		var resp pb.LightClientUpdateAltair
+		err = resp.UnmarshalSSZ(writer.Body.Bytes()[offset : offset+updateLen])
+		require.NoError(t, err)
+		require.DeepEqual(t, resp.AttestedHeader, updates[0].AttestedHeader().Proto())
+		offset += updateLen
+		updateLen = int(ssz.UnmarshallUint64(writer.Body.Bytes()[offset:offset+8]) - 4)
+		offset += 12
+		var resp1 pb.LightClientUpdateCapella
+		err = resp1.UnmarshalSSZ(writer.Body.Bytes()[offset : offset+updateLen])
+		require.NoError(t, err)
+		require.DeepEqual(t, resp1.AttestedHeader, updates[1].AttestedHeader().Proto())
+	})
+
 	t.Run("multiple forks - capella, deneb", func(t *testing.T) {
 		slotDeneb := primitives.Slot(config.DenebForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
 		slotCapella := primitives.Slot(config.CapellaForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
@@ -869,6 +1208,68 @@ func TestLightClientHandler_GetLightClientByRange(t *testing.T) {
 		}
 	})
 
+	t.Run("multiple forks - capella, deneb - ssz", func(t *testing.T) {
+		slotDeneb := primitives.Slot(config.DenebForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
+		slotCapella := primitives.Slot(config.CapellaForkEpoch * primitives.Epoch(config.SlotsPerEpoch)).Add(1)
+
+		st, err := util.NewBeaconStateAltair()
+		require.NoError(t, err)
+		headSlot := slotDeneb.Add(1)
+		err = st.SetSlot(headSlot)
+		require.NoError(t, err)
+
+		db := dbtesting.SetupDB(t)
+
+		updates := make([]interfaces.LightClientUpdate, 2)
+
+		updatePeriod := slotCapella.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+
+		updates[0], err = createUpdate(t, version.Capella)
+		require.NoError(t, err)
+
+		err = db.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[0])
+		require.NoError(t, err)
+
+		updatePeriod = slotDeneb.Div(uint64(config.EpochsPerSyncCommitteePeriod)).Div(uint64(config.SlotsPerEpoch))
+
+		updates[1], err = createUpdate(t, version.Deneb)
+		require.NoError(t, err)
+
+		err = db.SaveLightClientUpdate(ctx, uint64(updatePeriod), updates[1])
+		require.NoError(t, err)
+
+		mockChainService := &mock.ChainService{State: st}
+		s := &Server{
+			HeadFetcher: mockChainService,
+			BeaconDB:    db,
+		}
+		startPeriod := 1
+		url := fmt.Sprintf("http://foo.com/?count=100&start_period=%d", startPeriod)
+		request := httptest.NewRequest("GET", url, nil)
+		request.Header.Add("Accept", "application/octet-stream")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+
+		s.GetLightClientUpdatesByRange(writer, request)
+
+		require.Equal(t, http.StatusOK, writer.Code)
+
+		offset := 0
+		updateLen := int(ssz.UnmarshallUint64(writer.Body.Bytes()[offset:offset+8]) - 4)
+		offset += 12
+		var resp pb.LightClientUpdateCapella
+		err = resp.UnmarshalSSZ(writer.Body.Bytes()[offset : offset+updateLen])
+		require.NoError(t, err)
+		require.DeepEqual(t, resp.AttestedHeader, updates[0].AttestedHeader().Proto())
+		offset += updateLen
+		updateLen = int(ssz.UnmarshallUint64(writer.Body.Bytes()[offset:offset+8]) - 4)
+		offset += 12
+		var resp1 pb.LightClientUpdateDeneb
+		err = resp1.UnmarshalSSZ(writer.Body.Bytes()[offset : offset+updateLen])
+		require.NoError(t, err)
+		require.DeepEqual(t, resp1.AttestedHeader, updates[1].AttestedHeader().Proto())
+	})
+
 	t.Run("count bigger than limit", func(t *testing.T) {
 		config.MaxRequestLightClientUpdates = 2
 		params.OverrideBeaconConfig(config)

changelog/bastin_lightclient-updates-ssz.md

@@ -0,0 +1,3 @@
+### Added
+
+- Add SSZ support to light client updates by range API. [[PR]](https://github.com/prysmaticlabs/prysm/pull/15082)

proto/prysm/v1alpha1/electra.ssz.go

@@ -5279,7 +5279,7 @@ func (l *LightClientFinalityUpdateElectra) MarshalSSZ() ([]byte, error) {
 // MarshalSSZTo ssz marshals the LightClientFinalityUpdateElectra object to a target array
 func (l *LightClientFinalityUpdateElectra) MarshalSSZTo(buf []byte) (dst []byte, err error) {
 	dst = buf
-	offset := int(180)
+	offset := int(400)
 
 	// Offset (0) 'AttestedHeader'
 	dst = ssz.WriteOffset(dst, offset)
@@ -5295,11 +5295,17 @@ func (l *LightClientFinalityUpdateElectra) MarshalSSZTo(buf []byte) (dst []byte,
 	}
 	offset += l.FinalizedHeader.SizeSSZ()
 
-	// Offset (2) 'FinalityBranch'
-	dst = ssz.WriteOffset(dst, offset)
-	for ii := 0; ii < len(l.FinalityBranch); ii++ {
-		offset += 4
-		offset += len(l.FinalityBranch[ii])
+	// Field (2) 'FinalityBranch'
+	if size := len(l.FinalityBranch); size != 7 {
+		err = ssz.ErrVectorLengthFn("--.FinalityBranch", size, 7)
+		return
+	}
+	for ii := 0; ii < 7; ii++ {
+		if size := len(l.FinalityBranch[ii]); size != 32 {
+			err = ssz.ErrBytesLengthFn("--.FinalityBranch[ii]", size, 32)
+			return
+		}
+		dst = append(dst, l.FinalityBranch[ii]...)
 	}
 
 	// Field (3) 'SyncAggregate'
@@ -5323,26 +5329,6 @@ func (l *LightClientFinalityUpdateElectra) MarshalSSZTo(buf []byte) (dst []byte,
 		return
 	}
 
-	// Field (2) 'FinalityBranch'
-	if size := len(l.FinalityBranch); size > 7 {
-		err = ssz.ErrListTooBigFn("--.FinalityBranch", size, 7)
-		return
-	}
-	{
-		offset = 4 * len(l.FinalityBranch)
-		for ii := 0; ii < len(l.FinalityBranch); ii++ {
-			dst = ssz.WriteOffset(dst, offset)
-			offset += len(l.FinalityBranch[ii])
-		}
-	}
-	for ii := 0; ii < len(l.FinalityBranch); ii++ {
-		if size := len(l.FinalityBranch[ii]); size > 32 {
-			err = ssz.ErrBytesLengthFn("--.FinalityBranch[ii]", size, 32)
-			return
-		}
-		dst = append(dst, l.FinalityBranch[ii]...)
-	}
-
 	return
 }
 
@@ -5350,19 +5336,19 @@ func (l *LightClientFinalityUpdateElectra) MarshalSSZTo(buf []byte) (dst []byte,
 func (l *LightClientFinalityUpdateElectra) UnmarshalSSZ(buf []byte) error {
 	var err error
 	size := uint64(len(buf))
-	if size < 180 {
+	if size < 400 {
 		return ssz.ErrSize
 	}
 
 	tail := buf
-	var o0, o1, o2 uint64
+	var o0, o1 uint64
 
 	// Offset (0) 'AttestedHeader'
 	if o0 = ssz.ReadOffset(buf[0:4]); o0 > size {
 		return ssz.ErrOffset
 	}
 
-	if o0 != 180 {
+	if o0 != 400 {
 		return ssz.ErrInvalidVariableOffset
 	}
 
@@ -5371,21 +5357,25 @@ func (l *LightClientFinalityUpdateElectra) UnmarshalSSZ(buf []byte) error {
 		return ssz.ErrOffset
 	}
 
-	// Offset (2) 'FinalityBranch'
-	if o2 = ssz.ReadOffset(buf[8:12]); o2 > size || o1 > o2 {
-		return ssz.ErrOffset
+	// Field (2) 'FinalityBranch'
+	l.FinalityBranch = make([][]byte, 7)
+	for ii := 0; ii < 7; ii++ {
+		if cap(l.FinalityBranch[ii]) == 0 {
+			l.FinalityBranch[ii] = make([]byte, 0, len(buf[8:232][ii*32:(ii+1)*32]))
+		}
+		l.FinalityBranch[ii] = append(l.FinalityBranch[ii], buf[8:232][ii*32:(ii+1)*32]...)
 	}
 
 	// Field (3) 'SyncAggregate'
 	if l.SyncAggregate == nil {
 		l.SyncAggregate = new(SyncAggregate)
 	}
-	if err = l.SyncAggregate.UnmarshalSSZ(buf[12:172]); err != nil {
+	if err = l.SyncAggregate.UnmarshalSSZ(buf[232:392]); err != nil {
 		return err
 	}
 
 	// Field (4) 'SignatureSlot'
-	l.SignatureSlot = github_com_prysmaticlabs_prysm_v5_consensus_types_primitives.Slot(ssz.UnmarshallUint64(buf[172:180]))
+	l.SignatureSlot = github_com_prysmaticlabs_prysm_v5_consensus_types_primitives.Slot(ssz.UnmarshallUint64(buf[392:400]))
 
 	// Field (0) 'AttestedHeader'
 	{
@@ -5400,7 +5390,7 @@ func (l *LightClientFinalityUpdateElectra) UnmarshalSSZ(buf []byte) error {
 
 	// Field (1) 'FinalizedHeader'
 	{
-		buf = tail[o1:o2]
+		buf = tail[o1:]
 		if l.FinalizedHeader == nil {
 			l.FinalizedHeader = new(LightClientHeaderDeneb)
 		}
@@ -5408,35 +5398,12 @@ func (l *LightClientFinalityUpdateElectra) UnmarshalSSZ(buf []byte) error {
 			return err
 		}
 	}
-
-	// Field (2) 'FinalityBranch'
-	{
-		buf = tail[o2:]
-		num, err := ssz.DecodeDynamicLength(buf, 7)
-		if err != nil {
-			return err
-		}
-		l.FinalityBranch = make([][]byte, num)
-		err = ssz.UnmarshalDynamic(buf, num, func(indx int, buf []byte) (err error) {
-			if len(buf) > 32 {
-				return ssz.ErrBytesLength
-			}
-			if cap(l.FinalityBranch[indx]) == 0 {
-				l.FinalityBranch[indx] = make([]byte, 0, len(buf))
-			}
-			l.FinalityBranch[indx] = append(l.FinalityBranch[indx], buf...)
-			return nil
-		})
-		if err != nil {
-			return err
-		}
-	}
 	return err
 }
 
 // SizeSSZ returns the ssz encoded size in bytes for the LightClientFinalityUpdateElectra object
 func (l *LightClientFinalityUpdateElectra) SizeSSZ() (size int) {
-	size = 180
+	size = 400
 
 	// Field (0) 'AttestedHeader'
 	if l.AttestedHeader == nil {
@@ -5450,12 +5417,6 @@ func (l *LightClientFinalityUpdateElectra) SizeSSZ() (size int) {
 	}
 	size += l.FinalizedHeader.SizeSSZ()
 
-	// Field (2) 'FinalityBranch'
-	for ii := 0; ii < len(l.FinalityBranch); ii++ {
-		size += 4
-		size += len(l.FinalityBranch[ii])
-	}
-
 	return
 }
 
@@ -5480,25 +5441,19 @@ func (l *LightClientFinalityUpdateElectra) HashTreeRootWith(hh *ssz.Hasher) (err
 
 	// Field (2) 'FinalityBranch'
 	{
+		if size := len(l.FinalityBranch); size != 7 {
+			err = ssz.ErrVectorLengthFn("--.FinalityBranch", size, 7)
+			return
+		}
 		subIndx := hh.Index()
-		num := uint64(len(l.FinalityBranch))
-		if num > 7 {
-			err = ssz.ErrIncorrectListSize
+		for _, i := range l.FinalityBranch {
+			if len(i) != 32 {
+				err = ssz.ErrBytesLength
 				return
 			}
-		for _, elem := range l.FinalityBranch {
-			{
-				elemIndx := hh.Index()
-				byteLen := uint64(len(elem))
-				if byteLen > 32 {
-					err = ssz.ErrIncorrectListSize
-					return
+			hh.Append(i)
 		}
-				hh.AppendBytes32(elem)
-				hh.MerkleizeWithMixin(elemIndx, byteLen, (32+31)/32)
-			}
-		}
-		hh.MerkleizeWithMixin(subIndx, num, 7)
+		hh.Merkleize(subIndx)
 	}
 
 	// Field (3) 'SyncAggregate'

proto/prysm/v1alpha1/light_client.pb.go

@@ -1262,7 +1262,7 @@ type LightClientFinalityUpdateElectra struct {
 
 	AttestedHeader  *LightClientHeaderDeneb                                           `protobuf:"bytes,1,opt,name=attested_header,json=attestedHeader,proto3" json:"attested_header,omitempty"`
 	FinalizedHeader *LightClientHeaderDeneb                                           `protobuf:"bytes,2,opt,name=finalized_header,json=finalizedHeader,proto3" json:"finalized_header,omitempty"`
-	FinalityBranch  [][]byte                                                          `protobuf:"bytes,3,rep,name=finality_branch,json=finalityBranch,proto3" json:"finality_branch,omitempty" ssz-max:"7,32"`
+	FinalityBranch  [][]byte                                                          `protobuf:"bytes,3,rep,name=finality_branch,json=finalityBranch,proto3" json:"finality_branch,omitempty" ssz-size:"7,32"`
 	SyncAggregate   *SyncAggregate                                                    `protobuf:"bytes,4,opt,name=sync_aggregate,json=syncAggregate,proto3" json:"sync_aggregate,omitempty"`
 	SignatureSlot   github_com_prysmaticlabs_prysm_v5_consensus_types_primitives.Slot `protobuf:"varint,5,opt,name=signature_slot,json=signatureSlot,proto3" json:"signature_slot,omitempty" cast-type:"github.com/prysmaticlabs/prysm/v5/consensus-types/primitives.Slot"`
 }
@@ -1762,7 +1762,7 @@ var file_proto_prysm_v1alpha1_light_client_proto_rawDesc = []byte{
 	0x48, 0x65, 0x61, 0x64, 0x65, 0x72, 0x44, 0x65, 0x6e, 0x65, 0x62, 0x52, 0x0f, 0x66, 0x69, 0x6e,
 	0x61, 0x6c, 0x69, 0x7a, 0x65, 0x64, 0x48, 0x65, 0x61, 0x64, 0x65, 0x72, 0x12, 0x31, 0x0a, 0x0f,
 	0x66, 0x69, 0x6e, 0x61, 0x6c, 0x69, 0x74, 0x79, 0x5f, 0x62, 0x72, 0x61, 0x6e, 0x63, 0x68, 0x18,
-	0x03, 0x20, 0x03, 0x28, 0x0c, 0x42, 0x08, 0x92, 0xb5, 0x18, 0x04, 0x37, 0x2c, 0x33, 0x32, 0x52,
+	0x03, 0x20, 0x03, 0x28, 0x0c, 0x42, 0x08, 0x8a, 0xb5, 0x18, 0x04, 0x37, 0x2c, 0x33, 0x32, 0x52,
 	0x0e, 0x66, 0x69, 0x6e, 0x61, 0x6c, 0x69, 0x74, 0x79, 0x42, 0x72, 0x61, 0x6e, 0x63, 0x68, 0x12,
 	0x4b, 0x0a, 0x0e, 0x73, 0x79, 0x6e, 0x63, 0x5f, 0x61, 0x67, 0x67, 0x72, 0x65, 0x67, 0x61, 0x74,
 	0x65, 0x18, 0x04, 0x20, 0x01, 0x28, 0x0b, 0x32, 0x24, 0x2e, 0x65, 0x74, 0x68, 0x65, 0x72, 0x65,

proto/prysm/v1alpha1/light_client.proto

@@ -204,7 +204,7 @@ message LightClientUpdateElectra {
 message LightClientFinalityUpdateElectra {
   LightClientHeaderDeneb attested_header = 1;
   LightClientHeaderDeneb finalized_header = 2;
-  repeated bytes finality_branch = 3 [ (ethereum.eth.ext.ssz_max) = "7,32" ];
+  repeated bytes finality_branch = 3 [ (ethereum.eth.ext.ssz_size) = "7,32" ];
   SyncAggregate sync_aggregate = 4;
   uint64 signature_slot = 5 [
     (ethereum.eth.ext.cast_type) =

proto/testing/test.pb.go

@@ -1,7 +1,7 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.33.0
-// 	protoc        v3.21.7
+// 	protoc-gen-go v1.31.0
+// 	protoc        v4.25.1
 // source: proto/testing/test.proto
 
 package testing