PeerDAS: Implement reconstruction. (#14036)

* Wrap errors, add logs.

* `missingColumnRequest`: Fix blobs <-> data columns mix.

* `ColumnIndices`: Return `map[uint64]bool` instead of `[fieldparams.NumberOfColumns]bool`.

* `DataColumnSidecars`: `interfaces.SignedBeaconBlock` ==> `interfaces.ReadOnlySignedBeaconBlock`.

We don't need any of the non read-only methods.

* Fix comments.

* `handleUnblidedBlock` ==> `handleUnblindedBlock`.

* `SaveDataColumn`: Move log from debug to trace.

If we attempt to save an already existing data column sidecar,
a debug log was printed.

This case could be quite common now with the data column reconstruction enabled.

* `sampling_data_columns.go` --> `data_columns_sampling.go`.

* Reconstruct data columns.

beacon-chain/core/peerdas/helpers.go

@@ -170,7 +170,7 @@ func RecoverMatrix(cellFromCoordinate map[cellCoordinate]cKzg4844.Cell, blobCoun
 
 // DataColumnSidecars computes the data column sidecars from the signed block and blobs.
 // https://github.com/ethereum/consensus-specs/blob/dev/specs/_features/eip7594/das-core.md#recover_matrix
-func DataColumnSidecars(signedBlock interfaces.SignedBeaconBlock, blobs []cKzg4844.Blob) ([]*ethpb.DataColumnSidecar, error) {
+func DataColumnSidecars(signedBlock interfaces.ReadOnlySignedBeaconBlock, blobs []cKzg4844.Blob) ([]*ethpb.DataColumnSidecar, error) {
 	blobsCount := len(blobs)
 	if blobsCount == 0 {
 		return nil, nil

beacon-chain/db/filesystem/blob.go

@@ -230,10 +230,12 @@ func (bs *BlobStorage) SaveDataColumn(column blocks.VerifiedRODataColumn) error
 	if err != nil {
 		return err
 	}
+
 	if exists {
-		log.Debug("Ignoring a duplicate data column sidecar save attempt")
+		log.Trace("Ignoring a duplicate data column sidecar save attempt")
 		return nil
 	}
+
 	if bs.pruner != nil {
 		hRoot, err := column.SignedBlockHeader.Header.HashTreeRoot()
 		if err != nil {
@@ -399,38 +401,58 @@ func (bs *BlobStorage) Indices(root [32]byte) ([fieldparams.MaxBlobsPerBlock]boo
 }
 
 // ColumnIndices retrieve the stored column indexes from our filesystem.
-func (bs *BlobStorage) ColumnIndices(root [32]byte) ([fieldparams.NumberOfColumns]bool, error) {
-	var mask [fieldparams.NumberOfColumns]bool
+func (bs *BlobStorage) ColumnIndices(root [32]byte) (map[uint64]bool, error) {
+	custody := make(map[uint64]bool, fieldparams.NumberOfColumns)
+
+	// Get all the files in the directory.
 	rootDir := blobNamer{root: root}.dir()
 	entries, err := afero.ReadDir(bs.fs, rootDir)
 	if err != nil {
+		// If the directory does not exist, we do not custody any columns.
 		if os.IsNotExist(err) {
-			return mask, nil
+			return nil, nil
 		}
-		return mask, err
+
+		return nil, errors.Wrap(err, "read directory")
 	}
-	for i := range entries {
-		if entries[i].IsDir() {
+
+	// Iterate over all the entries in the directory.
+	for _, entry := range entries {
+		// If the entry is a directory, skip it.
+		if entry.IsDir() {
 			continue
 		}
-		name := entries[i].Name()
+
+		// If the entry does not have the correct extension, skip it.
+		name := entry.Name()
 		if !strings.HasSuffix(name, sszExt) {
 			continue
 		}
+
+		// The file should be in the `<index>.<extension>` format.
+		// Skip the file if it does not match the format.
 		parts := strings.Split(name, ".")
 		if len(parts) != 2 {
 			continue
 		}
-		u, err := strconv.ParseUint(parts[0], 10, 64)
+
+		// Get the column index from the file name.
+		columnIndexStr := parts[0]
+		columnIndex, err := strconv.ParseUint(columnIndexStr, 10, 64)
 		if err != nil {
-			return mask, errors.Wrapf(err, "unexpected directory entry breaks listing, %s", parts[0])
+			return nil, errors.Wrapf(err, "unexpected directory entry breaks listing, %s", parts[0])
 		}
-		if u >= fieldparams.NumberOfColumns {
-			return mask, errors.Wrapf(errIndexOutOfBounds, "invalid index %d", u)
+
+		// If the column index is out of bounds, return an error.
+		if columnIndex >= fieldparams.NumberOfColumns {
+			return nil, errors.Wrapf(errIndexOutOfBounds, "invalid index %d", columnIndex)
 		}
-		mask[u] = true
+
+		// Mark the column index as in custody.
+		custody[columnIndex] = true
 	}
-	return mask, nil
+
+	return custody, nil
 }
 
 // Clear deletes all files on the filesystem.

beacon-chain/p2p/custody.go

@@ -7,6 +7,7 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/peerdas"
 	"github.com/prysmaticlabs/prysm/v5/cmd/beacon-chain/flags"
 	"github.com/prysmaticlabs/prysm/v5/config/params"
+	"github.com/sirupsen/logrus"
 )
 
 func (s *Service) GetValidCustodyPeers(peers []peer.ID) ([]peer.ID, error) {
@@ -20,17 +21,15 @@ func (s *Service) GetValidCustodyPeers(peers []peer.ID) ([]peer.ID, error) {
 	}
 	var validPeers []peer.ID
 	for _, pid := range peers {
-		remoteCount, err := s.CustodyCountFromRemotePeer(pid)
-		if err != nil {
-			return nil, err
-		}
+		remoteCount := s.CustodyCountFromRemotePeer(pid)
+
 		nodeId, err := ConvertPeerIDToNodeID(pid)
 		if err != nil {
-			return nil, err
+			return nil, errors.Wrap(err, "convert peer ID to node ID")
 		}
 		remoteCustodiedColumns, err := peerdas.CustodyColumns(nodeId, remoteCount)
 		if err != nil {
-			return nil, err
+			return nil, errors.Wrap(err, "custody columns")
 		}
 		invalidPeer := false
 		for c := range custodiedColumns {
@@ -49,24 +48,36 @@ func (s *Service) GetValidCustodyPeers(peers []peer.ID) ([]peer.ID, error) {
 	return validPeers, nil
 }
 
-func (s *Service) CustodyCountFromRemotePeer(pid peer.ID) (uint64, error) {
+func (s *Service) CustodyCountFromRemotePeer(pid peer.ID) uint64 {
+	// By default, we assume the peer custodies the minimum number of subnets.
+	peerCustodyCountCount := params.BeaconConfig().CustodyRequirement
+
 	// Retrieve the ENR of the peer.
 	peerRecord, err := s.peers.ENR(pid)
 	if err != nil {
-		return 0, errors.Wrap(err, "ENR")
+		log.WithError(err).WithField("peerID", pid).Error("Failed to retrieve ENR for peer")
+		return peerCustodyCountCount
 	}
-	peerCustodiedSubnetCount := params.BeaconConfig().CustodyRequirement
-	if peerRecord != nil {
-		// Load the `custody_subnet_count`
-		custodyBytes := make([]byte, 8)
-		custodyObj := CustodySubnetCount(custodyBytes)
-		if err := peerRecord.Load(&custodyObj); err != nil {
-			return 0, errors.Wrap(err, "load custody_subnet_count")
-		}
-		actualCustodyCount := ssz.UnmarshallUint64(custodyObj)
-		if actualCustodyCount > peerCustodiedSubnetCount {
-			peerCustodiedSubnetCount = actualCustodyCount
-		}
+
+	if peerRecord == nil {
+		// This is the case for inbound peers. So we don't log an error for this.
+		log.WithField("peerID", pid).Debug("No ENR found for peer")
+		return peerCustodyCountCount
+	}
+
+	// Load the `custody_subnet_count`
+	custodyObj := CustodySubnetCount(make([]byte, 8))
+	if err := peerRecord.Load(&custodyObj); err != nil {
+		log.WithField("peerID", pid).Error("Cannot load the custody_subnet_count from peer")
+		return peerCustodyCountCount
 	}
-	return peerCustodiedSubnetCount, nil
+
+	// Unmarshal the custody count from the peer's ENR.
+	peerCustodyCountFromRecord := ssz.UnmarshallUint64(custodyObj)
+	log.WithFields(logrus.Fields{
+		"peerID":       pid,
+		"custodyCount": peerCustodyCountFromRecord,
+	}).Debug("Custody count read from peer's ENR")
+
+	return peerCustodyCountFromRecord
 }

beacon-chain/p2p/interfaces.go

@@ -113,6 +113,6 @@ type MetadataProvider interface {
 }
 
 type CustodyHandler interface {
-	CustodyCountFromRemotePeer(peer.ID) (uint64, error)
+	CustodyCountFromRemotePeer(peer.ID) uint64
 	GetValidCustodyPeers([]peer.ID) ([]peer.ID, error)
 }

beacon-chain/p2p/testing/fuzz_p2p.go

@@ -184,8 +184,8 @@ func (*FakeP2P) InterceptUpgraded(network.Conn) (allow bool, reason control.Disc
 	return true, 0
 }
 
-func (_ *FakeP2P) CustodyCountFromRemotePeer(peer.ID) (uint64, error) {
-	return 0, nil
+func (_ *FakeP2P) CustodyCountFromRemotePeer(peer.ID) uint64 {
+	return 0
 }
 
 func (_ *FakeP2P) GetValidCustodyPeers(peers []peer.ID) ([]peer.ID, error) {

beacon-chain/p2p/testing/p2p.go

@@ -427,8 +427,8 @@ func (_ *TestP2P) InterceptUpgraded(network.Conn) (allow bool, reason control.Di
 	return true, 0
 }
 
-func (_ *TestP2P) CustodyCountFromRemotePeer(peer.ID) (uint64, error) {
-	return 0, nil
+func (_ *TestP2P) CustodyCountFromRemotePeer(peer.ID) uint64 {
+	return 0
 }
 
 func (_ *TestP2P) GetValidCustodyPeers(peers []peer.ID) ([]peer.ID, error) {

beacon-chain/sync/BUILD.bazel

@@ -7,6 +7,8 @@ go_library(
         "block_batcher.go",
         "broadcast_bls_changes.go",
         "context.go",
+        "data_columns_reconstruct.go",
+        "data_columns_sampling.go",
         "deadlines.go",
         "decode_pubsub.go",
         "doc.go",
@@ -32,7 +34,6 @@ go_library(
         "rpc_ping.go",
         "rpc_send_request.go",
         "rpc_status.go",
-        "sampling_data_columns.go",
         "service.go",
         "subscriber.go",
         "subscriber_beacon_aggregate_proof.go",
@@ -129,6 +130,7 @@ go_library(
         "//time:go_default_library",
         "//time/slots:go_default_library",
         "@com_github_btcsuite_btcd_btcec_v2//:go_default_library",
+        "@com_github_ethereum_c_kzg_4844//bindings/go:go_default_library",
         "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
         "@com_github_ethereum_go_ethereum//common/math:go_default_library",
         "@com_github_ethereum_go_ethereum//crypto:go_default_library",