FIX: removing extra container for ssz blob sidecar response (#14451)

* removing extra container for ssz blob sidecar response

* gaz and changelog

* gaz

* fixing dependencies

* fixing test

* updating values based on feedback"

CHANGELOG.md

@@ -60,6 +60,7 @@ The format is based on Keep a Changelog, and this project adheres to Semantic Ve
 - `== nil` checks before calling `IsNil()` on interfaces to prevent panics.
 - Core: Fixed slash processing causing extra hashing
 - Core: Fixed extra allocations when processing slashings
+- remove unneeded container in blob sidecar ssz response
 
 ### Security
 

beacon-chain/db/filesystem/cache.go

@@ -114,5 +114,5 @@ func (s *blobStorageCache) evict(key [32]byte) {
 func (s *blobStorageCache) updateMetrics(delta float64) {
 	s.nBlobs += delta
 	blobDiskCount.Set(s.nBlobs)
-	blobDiskSize.Set(s.nBlobs * bytesPerSidecar)
+	blobDiskSize.Set(s.nBlobs * fieldparams.BlobSidecarSize)
 }

beacon-chain/db/filesystem/pruner.go

@@ -21,7 +21,6 @@ import (
 )
 
 const retentionBuffer primitives.Epoch = 2
-const bytesPerSidecar = 131928
 
 var (
 	errPruningFailures = errors.New("blobs could not be pruned for some roots")

beacon-chain/rpc/eth/blob/BUILD.bazel

@@ -13,10 +13,11 @@ go_library(
         "//beacon-chain/rpc/core:go_default_library",
         "//beacon-chain/rpc/lookup:go_default_library",
         "//config/fieldparams:go_default_library",
+        "//consensus-types/blocks:go_default_library",
         "//monitoring/tracing/trace:go_default_library",
         "//network/httputil:go_default_library",
-        "//proto/prysm/v1alpha1:go_default_library",
         "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
+        "@com_github_pkg_errors//:go_default_library",
     ],
 )
 
@@ -32,6 +33,7 @@ go_test(
         "//beacon-chain/rpc/lookup:go_default_library",
         "//beacon-chain/rpc/testutil:go_default_library",
         "//beacon-chain/verification:go_default_library",
+        "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
         "//network/httputil:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",

beacon-chain/rpc/eth/blob/handlers.go

@@ -8,19 +8,19 @@ import (
 	"strings"
 
 	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/v5/api/server/structs"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/rpc/core"
 	field_params "github.com/prysmaticlabs/prysm/v5/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/v5/consensus-types/blocks"
 	"github.com/prysmaticlabs/prysm/v5/monitoring/tracing/trace"
 	"github.com/prysmaticlabs/prysm/v5/network/httputil"
-	eth "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
 )
 
 // Blobs is an HTTP handler for Beacon API getBlobs.
 func (s *Server) Blobs(w http.ResponseWriter, r *http.Request) {
 	ctx, span := trace.StartSpan(r.Context(), "beacon.Blobs")
 	defer span.End()
-	var sidecars []*eth.BlobSidecar
 
 	indices, err := parseIndices(r.URL)
 	if err != nil {
@@ -48,14 +48,9 @@ func (s *Server) Blobs(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 	}
-	for i := range verifiedBlobs {
-		sidecars = append(sidecars, verifiedBlobs[i].BlobSidecar)
-	}
+
 	if httputil.RespondWithSsz(r) {
-		sidecarResp := &eth.BlobSidecars{
-			Sidecars: sidecars,
-		}
-		sszResp, err := sidecarResp.MarshalSSZ()
+		sszResp, err := buildSidecarsSSZResponse(verifiedBlobs)
 		if err != nil {
 			httputil.HandleError(w, err.Error(), http.StatusInternalServerError)
 			return
@@ -64,7 +59,7 @@ func (s *Server) Blobs(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	httputil.WriteJson(w, buildSidecarsResponse(sidecars))
+	httputil.WriteJson(w, buildSidecarsJsonResponse(verifiedBlobs))
 }
 
 // parseIndices filters out invalid and duplicate blob indices
@@ -97,9 +92,9 @@ loop:
 	return indices, nil
 }
 
-func buildSidecarsResponse(sidecars []*eth.BlobSidecar) *structs.SidecarsResponse {
-	resp := &structs.SidecarsResponse{Data: make([]*structs.Sidecar, len(sidecars))}
-	for i, sc := range sidecars {
+func buildSidecarsJsonResponse(verifiedBlobs []*blocks.VerifiedROBlob) *structs.SidecarsResponse {
+	resp := &structs.SidecarsResponse{Data: make([]*structs.Sidecar, len(verifiedBlobs))}
+	for i, sc := range verifiedBlobs {
 		proofs := make([]string, len(sc.CommitmentInclusionProof))
 		for j := range sc.CommitmentInclusionProof {
 			proofs[j] = hexutil.Encode(sc.CommitmentInclusionProof[j])
@@ -115,3 +110,15 @@ func buildSidecarsResponse(sidecars []*eth.BlobSidecar) *structs.SidecarsRespons
 	}
 	return resp
 }
+
+func buildSidecarsSSZResponse(verifiedBlobs []*blocks.VerifiedROBlob) ([]byte, error) {
+	ssz := make([]byte, field_params.BlobSidecarSize*len(verifiedBlobs))
+	for i, sidecar := range verifiedBlobs {
+		sszrep, err := sidecar.MarshalSSZ()
+		if err != nil {
+			return nil, errors.Wrap(err, "failed to marshal sidecar ssz")
+		}
+		copy(ssz[i*field_params.BlobSidecarSize:(i+1)*field_params.BlobSidecarSize], sszrep)
+	}
+	return ssz, nil
+}

beacon-chain/rpc/eth/blob/handlers_test.go

@@ -20,6 +20,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/rpc/lookup"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/rpc/testutil"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/verification"
+	fieldparams "github.com/prysmaticlabs/prysm/v5/config/fieldparams"
 	"github.com/prysmaticlabs/prysm/v5/config/params"
 	"github.com/prysmaticlabs/prysm/v5/network/httputil"
 	eth "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
@@ -366,7 +367,32 @@ func TestBlobs(t *testing.T) {
 		}
 		s.Blobs(writer, request)
 		assert.Equal(t, http.StatusOK, writer.Code)
-		require.Equal(t, len(writer.Body.Bytes()), 131932)
+		require.Equal(t, len(writer.Body.Bytes()), fieldparams.BlobSidecarSize) // size of each sidecar
+		// can directly unmarshal to sidecar since there's only 1
+		var sidecar eth.BlobSidecar
+		require.NoError(t, sidecar.UnmarshalSSZ(writer.Body.Bytes()))
+		require.NotNil(t, sidecar.Blob)
+	})
+	t.Run("ssz multiple blobs", func(t *testing.T) {
+		u := "http://foo.example/finalized"
+		request := httptest.NewRequest("GET", u, nil)
+		request.Header.Add("Accept", "application/octet-stream")
+		writer := httptest.NewRecorder()
+		writer.Body = &bytes.Buffer{}
+		blocker := &lookup.BeaconDbBlocker{
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &eth.Checkpoint{Root: blockRoot[:]}},
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:    db,
+			BlobStorage: bs,
+		}
+		s := &Server{
+			Blocker: blocker,
+		}
+		s.Blobs(writer, request)
+		assert.Equal(t, http.StatusOK, writer.Code)
+		require.Equal(t, len(writer.Body.Bytes()), fieldparams.BlobSidecarSize*4) // size of each sidecar
 	})
 }
 

config/fieldparams/mainnet.go

@@ -31,6 +31,7 @@ const (
 	LogMaxBlobCommitments                 = 12            // Log_2 of MaxBlobCommitmentsPerBlock
 	BlobLength                            = 131072        // BlobLength defines the byte length of a blob.
 	BlobSize                              = 131072        // defined to match blob.size in bazel ssz codegen
+	BlobSidecarSize                       = 131928        // defined to match blob sidecar size in bazel ssz codegen
 	KzgCommitmentInclusionProofDepth      = 17            // Merkle proof depth for blob_kzg_commitments list item
 	NextSyncCommitteeBranchDepth          = 5             // NextSyncCommitteeBranchDepth defines the depth of the next sync committee branch.
 	PendingBalanceDepositsLimit           = 134217728     // Maximum number of pending balance deposits in the beacon state.

config/fieldparams/minimal.go

@@ -31,6 +31,7 @@ const (
 	LogMaxBlobCommitments                 = 4             // Log_2 of MaxBlobCommitmentsPerBlock
 	BlobLength                            = 131072        // BlobLength defines the byte length of a blob.
 	BlobSize                              = 131072        // defined to match blob.size in bazel ssz codegen
+	BlobSidecarSize                       = 131928        // defined to match blob sidecar size in bazel ssz codegen
 	KzgCommitmentInclusionProofDepth      = 17            // Merkle proof depth for blob_kzg_commitments list item
 	NextSyncCommitteeBranchDepth          = 5             // NextSyncCommitteeBranchDepth defines the depth of the next sync committee branch.
 	PendingBalanceDepositsLimit           = 134217728     // Maximum number of pending balance deposits in the beacon state.