Use engine api get-blobs for block subscriber

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changelog

add proto marshal and unmarshal

Kasey's feedback

CHANGELOG.md

@@ -76,6 +76,7 @@ Updating to this release is recommended at your convenience.
 - fastssz version bump (better error messages).
 - SSE implementation that sheds stuck clients. [pr](https://github.com/prysmaticlabs/prysm/pull/14413)
 - Added GetPoolAttesterSlashingsV2 endpoint.
+- Use engine api get-blobs for block subscriber
 
 ### Changed
 

beacon-chain/execution/BUILD.bazel

@@ -37,6 +37,7 @@ go_library(
         "//beacon-chain/state:go_default_library",
         "//beacon-chain/state/state-native:go_default_library",
         "//beacon-chain/state/stategen:go_default_library",
+        "//beacon-chain/verification:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/blocks:go_default_library",
@@ -105,8 +106,11 @@ go_test(
         "//beacon-chain/db/testing:go_default_library",
         "//beacon-chain/execution/testing:go_default_library",
         "//beacon-chain/execution/types:go_default_library",
+        "//beacon-chain/forkchoice:go_default_library",
         "//beacon-chain/forkchoice/doubly-linked-tree:go_default_library",
+        "//beacon-chain/startup:go_default_library",
         "//beacon-chain/state/stategen:go_default_library",
+        "//beacon-chain/verification:go_default_library",
         "//config/fieldparams:go_default_library",
         "//config/params:go_default_library",
         "//consensus-types/blocks:go_default_library",

beacon-chain/execution/engine_client.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"math/big"
+	"slices"
 	"strings"
 	"time"
 
@@ -14,6 +15,7 @@ import (
 	"github.com/holiman/uint256"
 	"github.com/pkg/errors"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/execution/types"
+	"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/consensus-types/blocks"
@@ -23,6 +25,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/encoding/bytesutil"
 	"github.com/prysmaticlabs/prysm/v5/monitoring/tracing/trace"
 	pb "github.com/prysmaticlabs/prysm/v5/proto/engine/v1"
+	ethpb "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/v5/runtime/version"
 	"github.com/prysmaticlabs/prysm/v5/time/slots"
 	"github.com/sirupsen/logrus"
@@ -79,6 +82,8 @@ const (
 	GetPayloadBodiesByRangeV1 = "engine_getPayloadBodiesByRangeV1"
 	// ExchangeCapabilities request string for JSON-RPC.
 	ExchangeCapabilities = "engine_exchangeCapabilities"
+	// GetBlobsV1 request string for JSON-RPC.
+	GetBlobsV1 = "engine_getBlobsV1"
 	// Defines the seconds before timing out engine endpoints with non-block execution semantics.
 	defaultEngineTimeout = time.Second
 )
@@ -93,16 +98,15 @@ type ForkchoiceUpdatedResponse struct {
 	ValidationError string             `json:"validationError"`
 }
 
-// PayloadReconstructor defines a service that can reconstruct a full beacon
-// block with an execution payload from a signed beacon block and a connection
-// to an execution client's engine API.
-type PayloadReconstructor interface {
+// Reconstructor defines a service responsible for reconstructing full beacon chain objects by utilizing the execution API and making requests through the execution client.
+type Reconstructor interface {
 	ReconstructFullBlock(
 		ctx context.Context, blindedBlock interfaces.ReadOnlySignedBeaconBlock,
 	) (interfaces.SignedBeaconBlock, error)
 	ReconstructFullBellatrixBlockBatch(
 		ctx context.Context, blindedBlocks []interfaces.ReadOnlySignedBeaconBlock,
 	) ([]interfaces.SignedBeaconBlock, error)
+	ReconstructBlobSidecars(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock, blockRoot [32]byte, indices [6]bool) ([]blocks.VerifiedROBlob, error)
 }
 
 // EngineCaller defines a client that can interact with an Ethereum
@@ -494,6 +498,23 @@ func (s *Service) HeaderByNumber(ctx context.Context, number *big.Int) (*types.H
 	return hdr, err
 }
 
+// GetBlobs returns the blob and proof from the execution engine for the given versioned hashes.
+func (s *Service) GetBlobs(ctx context.Context, versionedHashes []common.Hash) ([]*pb.BlobAndProof, error) {
+	ctx, span := trace.StartSpan(ctx, "powchain.engine-api-client.GetBlobs")
+	defer span.End()
+	// If the execution engine does not support `GetBlobsV1`, return early to prevent encountering an error later.
+	s.capabilitiesLock.RLock()
+	if !slices.Contains(s.capabilities, GetBlobsV1) {
+		s.capabilitiesLock.RUnlock()
+		return nil, nil
+	}
+	s.capabilitiesLock.RUnlock()
+
+	result := make([]*pb.BlobAndProof, len(versionedHashes))
+	err := s.rpcClient.CallContext(ctx, &result, GetBlobsV1, versionedHashes)
+	return result, handleRPCError(err)
+}
+
 // ReconstructFullBlock takes in a blinded beacon block and reconstructs
 // a beacon block with a full execution payload via the engine API.
 func (s *Service) ReconstructFullBlock(
@@ -522,6 +543,104 @@ func (s *Service) ReconstructFullBellatrixBlockBatch(
 	return unb, nil
 }
 
+// ReconstructBlobSidecars reconstructs the verified blob sidecars for a given beacon block.
+// It retrieves the KZG commitments from the block body, fetches the associated blobs and proofs,
+// and constructs the corresponding verified read-only blob sidecars.
+//
+// The 'exists' argument is a boolean array of length 6, where each element corresponds to whether a
+// particular blob sidecar already exists. If exists[i] is true, the blob for the i-th KZG commitment
+// has already been retrieved and does not need to be fetched again from the execution layer (EL).
+//
+// For example:
+//   - If exists = [true, false, true, false, true, false], the function will fetch the blobs
+//     associated with indices 1, 3, and 5 (since those are marked as non-existent).
+//   - If exists = [false ... x 6], the function will attempt to fetch all blobs.
+//
+// Only the blobs that do not already exist (where exists[i] is false) are fetched using the KZG commitments from block body.
+func (s *Service) ReconstructBlobSidecars(ctx context.Context, block interfaces.ReadOnlySignedBeaconBlock, blockRoot [32]byte, exists [6]bool) ([]blocks.VerifiedROBlob, error) {
+	blockBody := block.Block().Body()
+	kzgCommitments, err := blockBody.BlobKzgCommitments()
+	if err != nil {
+		return nil, errors.Wrap(err, "could not get blob KZG commitments")
+	}
+
+	// Collect KZG hashes for non-existing blobs
+	var kzgHashes []common.Hash
+	for i, commitment := range kzgCommitments {
+		if !exists[i] {
+			kzgHashes = append(kzgHashes, primitives.ConvertKzgCommitmentToVersionedHash(commitment))
+		}
+	}
+	if len(kzgHashes) == 0 {
+		return nil, nil
+	}
+
+	// Fetch blobs from EL
+	blobs, err := s.GetBlobs(ctx, kzgHashes)
+	if err != nil {
+		return nil, errors.Wrap(err, "could not get blobs")
+	}
+	if blobs == nil {
+		return nil, nil
+	}
+
+	header, err := block.Header()
+	if err != nil {
+		return nil, errors.Wrap(err, "could not get header")
+	}
+
+	// Reconstruct verify blob sidecars
+	var verifiedBlobs []blocks.VerifiedROBlob
+	for i, blobIndex := 0, 0; i < len(kzgCommitments); i++ {
+		if exists[i] {
+			continue
+		}
+
+		blob := blobs[blobIndex]
+		blobIndex++
+		if blob == nil {
+			continue
+		}
+
+		proof, err := blocks.MerkleProofKZGCommitment(blockBody, i)
+		if err != nil {
+			log.WithError(err).WithField("index", i).Error("failed to get Merkle proof for KZG commitment")
+			continue
+		}
+		sidecar := &ethpb.BlobSidecar{
+			Index:                    uint64(i),
+			Blob:                     blob.Blob,
+			KzgCommitment:            kzgCommitments[i],
+			KzgProof:                 blob.KzgProof,
+			SignedBlockHeader:        header,
+			CommitmentInclusionProof: proof,
+		}
+
+		roBlob, err := blocks.NewROBlobWithRoot(sidecar, blockRoot)
+		if err != nil {
+			log.WithError(err).WithField("index", i).Error("failed to create RO blob with root")
+			continue
+		}
+
+		// Verify the sidecar KZG proof
+		v := s.blobVerifier(roBlob, verification.ELMemPoolRequirements)
+		if err := v.SidecarKzgProofVerified(); err != nil {
+			log.WithError(err).WithField("index", i).Error("failed to verify KZG proof for sidecar")
+			continue
+		}
+
+		verifiedBlob, err := v.VerifiedROBlob()
+		if err != nil {
+			log.WithError(err).WithField("index", i).Error("failed to verify RO blob")
+			continue
+		}
+
+		verifiedBlobs = append(verifiedBlobs, verifiedBlob)
+	}
+
+	return verifiedBlobs, nil
+}
+
 func fullPayloadFromPayloadBody(
 	header interfaces.ExecutionData, body *pb.ExecutionPayloadBody, bVersion int,
 ) (interfaces.ExecutionData, error) {

beacon-chain/execution/engine_client_test.go

@@ -2,6 +2,7 @@ package execution
 
 import (
 	"context"
+	"crypto/rand"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -20,6 +21,7 @@ import (
 	"github.com/holiman/uint256"
 	"github.com/pkg/errors"
 	mocks "github.com/prysmaticlabs/prysm/v5/beacon-chain/execution/testing"
+	"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/consensus-types/blocks"
@@ -37,9 +39,9 @@ import (
 )
 
 var (
-	_ = PayloadReconstructor(&Service{})
+	_ = Reconstructor(&Service{})
 	_ = EngineCaller(&Service{})
-	_ = PayloadReconstructor(&Service{})
+	_ = Reconstructor(&Service{})
 	_ = EngineCaller(&mocks.EngineClient{})
 )
 
@@ -2390,3 +2392,108 @@ func Test_ExchangeCapabilities(t *testing.T) {
 		}
 	})
 }
+
+func TestReconstructBlobSidecars(t *testing.T) {
+	client := &Service{}
+	b := util.NewBeaconBlockDeneb()
+	kzgCommitments := createRandomKzgCommitments(t, 6)
+
+	b.Block.Body.BlobKzgCommitments = kzgCommitments
+	r, err := b.Block.HashTreeRoot()
+	require.NoError(t, err)
+	sb, err := blocks.NewSignedBeaconBlock(b)
+	require.NoError(t, err)
+
+	ctx := context.Background()
+	t.Run("all seen", func(t *testing.T) {
+		exists := [6]bool{true, true, true, true, true, true}
+		verifiedBlobs, err := client.ReconstructBlobSidecars(ctx, sb, r, exists)
+		require.NoError(t, err)
+		require.Equal(t, 0, len(verifiedBlobs))
+	})
+
+	t.Run("get-blobs end point is not supported", func(t *testing.T) {
+		exists := [6]bool{true, true, true, true, true, false}
+		verifiedBlobs, err := client.ReconstructBlobSidecars(ctx, sb, r, exists)
+		require.NoError(t, err)
+		require.Equal(t, 0, len(verifiedBlobs))
+	})
+
+	t.Run("recovered 6 missing blobs", func(t *testing.T) {
+		srv := createBlobServer(t, 6)
+		defer srv.Close()
+
+		rpcClient, client := setupRpcClient(t, srv.URL, client)
+		defer rpcClient.Close()
+
+		exists := [6]bool{}
+		verifiedBlobs, err := client.ReconstructBlobSidecars(ctx, sb, r, exists)
+		require.NoError(t, err)
+		require.Equal(t, 6, len(verifiedBlobs))
+	})
+
+	t.Run("recovered 3 missing blobs", func(t *testing.T) {
+		srv := createBlobServer(t, 3)
+		defer srv.Close()
+
+		rpcClient, client := setupRpcClient(t, srv.URL, client)
+		defer rpcClient.Close()
+
+		exists := [6]bool{true, false, true, false, true, false}
+		verifiedBlobs, err := client.ReconstructBlobSidecars(ctx, sb, r, exists)
+		require.NoError(t, err)
+		require.Equal(t, 3, len(verifiedBlobs))
+	})
+}
+
+func createRandomKzgCommitments(t *testing.T, num int) [][]byte {
+	kzgCommitments := make([][]byte, num)
+	for i := range kzgCommitments {
+		kzgCommitments[i] = make([]byte, 48)
+		_, err := rand.Read(kzgCommitments[i])
+		require.NoError(t, err)
+	}
+	return kzgCommitments
+}
+
+func createBlobServer(t *testing.T, numBlobs int) *httptest.Server {
+	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		defer func() {
+			require.NoError(t, r.Body.Close())
+		}()
+
+		blobs := make([]pb.BlobAndProofJson, numBlobs)
+		for i := range blobs {
+			blobs[i] = pb.BlobAndProofJson{Blob: []byte(fmt.Sprintf("blob%d", i+1)), KzgProof: []byte(fmt.Sprintf("proof%d", i+1))}
+		}
+
+		respJSON := map[string]interface{}{
+			"jsonrpc": "2.0",
+			"id":      1,
+			"result":  blobs,
+		}
+		require.NoError(t, json.NewEncoder(w).Encode(respJSON))
+	}))
+}
+
+func setupRpcClient(t *testing.T, url string, client *Service) (*rpc.Client, *Service) {
+	rpcClient, err := rpc.DialHTTP(url)
+	require.NoError(t, err)
+
+	client.rpcClient = rpcClient
+	client.capabilities = []string{GetBlobsV1}
+	client.blobVerifier = testNewBlobVerifier()
+
+	return rpcClient, client
+}
+
+func testNewBlobVerifier() verification.NewBlobVerifier {
+	return func(b blocks.ROBlob, reqs []verification.Requirement) verification.BlobVerifier {
+		return &verification.MockBlobVerifier{
+			CbVerifiedROBlob: func() (blocks.VerifiedROBlob, error) {
+				return blocks.VerifiedROBlob{}, nil
+			},
+		}
+	}
+}

beacon-chain/execution/options.go

@@ -7,6 +7,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/db"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/state"
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/state/stategen"
+	"github.com/prysmaticlabs/prysm/v5/beacon-chain/verification"
 	"github.com/prysmaticlabs/prysm/v5/network"
 	"github.com/prysmaticlabs/prysm/v5/network/authorization"
 )
@@ -115,3 +116,11 @@ func WithJwtId(jwtId string) Option {
 		return nil
 	}
 }
+
+// WithVerifierWaiter gives the sync package direct access to the verifier waiter.
+func WithVerifierWaiter(v *verification.InitializerWaiter) Option {
+	return func(s *Service) error {
+		s.verifierWaiter = v
+		return nil
+	}
+}

beacon-chain/execution/rpc_connection.go

@@ -78,6 +78,15 @@ func (s *Service) pollConnectionStatus(ctx context.Context) {
 				currClient.Close()
 			}
 			log.WithField("endpoint", logs.MaskCredentialsLogging(s.cfg.currHttpEndpoint.Url)).Info("Connected to new endpoint")
+
+			c, err := s.ExchangeCapabilities(ctx)
+			if err != nil {
+				errorLogger(err, "Could not exchange capabilities with execution client")
+			}
+			s.capabilitiesLock.Lock()
+			s.capabilities = c
+			s.capabilitiesLock.Unlock()
+
 			return
 		case <-s.ctx.Done():
 			log.Debug("Received cancelled context,closing existing powchain service")