From 82a722725d26dcef6ea3cea9033f35357607406d Mon Sep 17 00:00:00 2001
From: Francis Li <francis.li@coinbase.com>
Date: Thu, 2 May 2024 16:46:46 -0700
Subject: [PATCH] Add blob handler to capture blob p2p messages and produce
 event

---
 eth/node_config.go |  4 ++--
 eth/pubsub.go      | 47 ++++++++++++++++++++++++++++++++++++++++++++++
 host/host.go       |  1 +
 3 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/eth/node_config.go b/eth/node_config.go
index fdfbb79..d372483 100644
--- a/eth/node_config.go
+++ b/eth/node_config.go
@@ -383,7 +383,7 @@ func desiredPubSubBaseTopics() []string {
 		p2p.GossipContributionAndProofMessage,
 		// p2p.GossipSyncCommitteeMessage,
 		p2p.GossipBlsToExecutionChangeMessage,
-		// p2p.GossipBlobSidecarMessage,
+		p2p.GossipBlobSidecarMessage,
 	}
 }
 
@@ -441,7 +441,7 @@ func hasSubnets(topic string) (subnets uint64, hasSubnets bool) {
 }
 
 func (n *NodeConfig) composeEthTopic(base string, encoder encoder.NetworkEncoding, subnet uint64) string {
-	if subnet > 1 { // as far as I know, there aren't subnets with index 0
+	if subnet > 0 { // as far as I know, there aren't subnets with index 0
 		return fmt.Sprintf(base, n.ForkDigest, subnet) + encoder.ProtocolSuffix()
 	} else {
 		return fmt.Sprintf(base, n.ForkDigest) + encoder.ProtocolSuffix()
diff --git a/eth/pubsub.go b/eth/pubsub.go
index 91f5a73..540f171 100644
--- a/eth/pubsub.go
+++ b/eth/pubsub.go
@@ -8,6 +8,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/ethereum/go-ethereum/common/hexutil"
 	pubsub "github.com/libp2p/go-libp2p-pubsub"
 	pubsubpb "github.com/libp2p/go-libp2p-pubsub/pb"
 	"github.com/libp2p/go-libp2p/core/peer"
@@ -108,6 +109,8 @@ func (p *PubSub) mapPubSubTopicWithHandlers(topic string) host.TopicHandler {
 	switch {
 	case strings.Contains(topic, p2p.GossipBlockMessage):
 		return p.handleBeaconBlock
+	case strings.Contains(topic, p2p.GossipBlobSidecarMessage):
+		return p.handleBlobSidecar
 	default:
 		return p.host.TracedTopicHandler(host.NoopHandler)
 	}
@@ -165,6 +168,50 @@ func (p *PubSub) handleBeaconBlock(ctx context.Context, msg *pubsub.Message) err
 	return nil
 }
 
+func (p *PubSub) handleBlobSidecar(ctx context.Context, msg *pubsub.Message) error {
+	switch p.cfg.ForkVersion {
+	case DenebForkVersion:
+		var blob ethtypes.BlobSidecar
+		err := p.cfg.Encoder.DecodeGossip(msg.Data, &blob)
+		if err != nil {
+			slog.Error("decode blob sidecar gossip message", tele.LogAttrError(err))
+			return err
+		}
+
+		slot := blob.GetSignedBlockHeader().GetHeader().GetSlot()
+		slotStart := p.cfg.GenesisTime.Add(time.Duration(slot) * p.cfg.SecondsPerSlot)
+		proposerIndex := blob.GetSignedBlockHeader().GetHeader().GetProposerIndex()
+
+		now := time.Now()
+		evt := &host.TraceEvent{
+			Type:      "HANDLE_MESSAGE",
+			PeerID:    p.host.ID(),
+			Timestamp: now,
+			Payload: map[string]any{
+				"PeerID":     msg.ReceivedFrom.String(),
+				"MsgID":      hex.EncodeToString([]byte(msg.ID)),
+				"MsgSize":    len(msg.Data),
+				"Topic":      msg.GetTopic(),
+				"Seq":        msg.GetSeqno(),
+				"Slot":       slot,
+				"ValIdx":     proposerIndex,
+				"TimeInSlot": now.Sub(slotStart).Seconds(),
+				"StateRoot":  hexutil.Encode(blob.GetSignedBlockHeader().GetHeader().GetStateRoot()),
+				"BodyRoot":   hexutil.Encode(blob.GetSignedBlockHeader().GetHeader().GetBodyRoot()),
+				"ParentRoot": hexutil.Encode(blob.GetSignedBlockHeader().GetHeader().GetParentRoot()),
+			},
+		}
+
+		if err := p.cfg.DataStream.PutRecord(ctx, evt); err != nil {
+			slog.Warn("failed putting topic handler event", tele.LogAttrError(err))
+		}
+	default:
+		return fmt.Errorf("non recognized fork-version: %d", p.cfg.ForkVersion[:])
+	}
+
+	return nil
+}
+
 type GenericSignedBeaconBlock interface {
 	GetBlock() GenericBeaconBlock
 }
diff --git a/host/host.go b/host/host.go
index f07e0e2..e09dc24 100644
--- a/host/host.go
+++ b/host/host.go
@@ -270,6 +270,7 @@ func (h *Host) PrivateListenMaddr() (ma.Multiaddr, error) {
 
 func (h *Host) TracedTopicHandler(handler TopicHandler) TopicHandler {
 	return func(ctx context.Context, msg *pubsub.Message) error {
+		slog.Debug("Handling gossip message", "topic", msg.GetTopic())
 		evt := &TraceEvent{
 			Type:      "HANDLE_MESSAGE",
 			PeerID:    h.ID(),