prysm/beacon-chain/p2p/broadcaster_test.go

package p2p

import (
	"context"
	"fmt"
	"net"
	"reflect"
	"sync"
	"testing"
	"time"

	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/kzg"
	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/helpers"
	lightClient "github.com/OffchainLabs/prysm/v6/beacon-chain/core/light-client"
	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/peerdas"
	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/peers"
	"github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/peers/scorers"
	p2ptest "github.com/OffchainLabs/prysm/v6/beacon-chain/p2p/testing"
	"github.com/OffchainLabs/prysm/v6/cmd/beacon-chain/flags"
	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
	"github.com/OffchainLabs/prysm/v6/consensus-types/interfaces"
	"github.com/OffchainLabs/prysm/v6/consensus-types/wrapper"
	"github.com/OffchainLabs/prysm/v6/encoding/bytesutil"
	"github.com/OffchainLabs/prysm/v6/network/forks"
	ethpb "github.com/OffchainLabs/prysm/v6/proto/prysm/v1alpha1"
	testpb "github.com/OffchainLabs/prysm/v6/proto/testing"
	"github.com/OffchainLabs/prysm/v6/runtime/version"
	"github.com/OffchainLabs/prysm/v6/testing/assert"
	"github.com/OffchainLabs/prysm/v6/testing/require"
	"github.com/OffchainLabs/prysm/v6/testing/util"
	"github.com/OffchainLabs/prysm/v6/time/slots"
	pubsub "github.com/libp2p/go-libp2p-pubsub"
	"github.com/libp2p/go-libp2p/core/host"
	"github.com/prysmaticlabs/go-bitfield"
	"google.golang.org/protobuf/proto"
)

func TestService_Broadcast(t *testing.T) {
	p1 := p2ptest.NewTestP2P(t)
	p2 := p2ptest.NewTestP2P(t)
	p1.Connect(p2)
	if len(p1.BHost.Network().Peers()) == 0 {
		t.Fatal("No peers")
	}

	p := &Service{
		host:                  p1.BHost,
		pubsub:                p1.PubSub(),
		joinedTopics:          map[string]*pubsub.Topic{},
		cfg:                   &Config{},
		genesisTime:           time.Now(),
		genesisValidatorsRoot: bytesutil.PadTo([]byte{'A'}, 32),
	}

	msg := &ethpb.Fork{
		Epoch:           55,
		CurrentVersion:  []byte("fooo"),
		PreviousVersion: []byte("barr"),
	}

	topic := "/eth2/%x/testing"
	// Set a test gossip mapping for testpb.TestSimpleMessage.
	GossipTypeMapping[reflect.TypeOf(msg)] = topic
	digest, err := p.currentForkDigest()
	require.NoError(t, err)
	topic = fmt.Sprintf(topic, digest)

	// External peer subscribes to the topic.
	topic += p.Encoding().ProtocolSuffix()
	sub, err := p2.SubscribeToTopic(topic)
	require.NoError(t, err)

	time.Sleep(50 * time.Millisecond) // libp2p fails without this delay...

	// Async listen for the pubsub, must be before the broadcast.
	var wg sync.WaitGroup
	wg.Add(1)
	go func(tt *testing.T) {
		defer wg.Done()
		ctx, cancel := context.WithTimeout(t.Context(), 1*time.Second)
		defer cancel()

		incomingMessage, err := sub.Next(ctx)
		require.NoError(t, err)

		result := &ethpb.Fork{}
		require.NoError(t, p.Encoding().DecodeGossip(incomingMessage.Data, result))
		if !proto.Equal(result, msg) {
			tt.Errorf("Did not receive expected message, got %+v, wanted %+v", result, msg)
		}
	}(t)

	// Broadcast to peers and wait.
	require.NoError(t, p.Broadcast(t.Context(), msg))
	if util.WaitTimeout(&wg, 1*time.Second) {
		t.Error("Failed to receive pubsub within 1s")
	}
}

func TestService_Broadcast_ReturnsErr_TopicNotMapped(t *testing.T) {
	p := Service{
		genesisTime:           time.Now(),
		genesisValidatorsRoot: bytesutil.PadTo([]byte{'A'}, 32),
	}
	assert.ErrorContains(t, ErrMessageNotMapped.Error(), p.Broadcast(t.Context(), &testpb.AddressBook{}))
}

func TestService_Attestation_Subnet(t *testing.T) {
	if gtm := GossipTypeMapping[reflect.TypeOf(&ethpb.Attestation{})]; gtm != AttestationSubnetTopicFormat {
		t.Errorf("Constant is out of date. Wanted %s, got %s", AttestationSubnetTopicFormat, gtm)
	}

	tests := []struct {
		att   *ethpb.Attestation
		topic string
	}{
		{
			att: &ethpb.Attestation{
				Data: &ethpb.AttestationData{
					CommitteeIndex: 0,
					Slot:           2,
				},
			},
			topic: "/eth2/00000000/beacon_attestation_2",
		},
		{
			att: &ethpb.Attestation{
				Data: &ethpb.AttestationData{
					CommitteeIndex: 11,
					Slot:           10,
				},
			},
			topic: "/eth2/00000000/beacon_attestation_21",
		},
		{
			att: &ethpb.Attestation{
				Data: &ethpb.AttestationData{
					CommitteeIndex: 55,
					Slot:           529,
				},
			},
			topic: "/eth2/00000000/beacon_attestation_8",
		},
	}
	for _, tt := range tests {
		subnet := helpers.ComputeSubnetFromCommitteeAndSlot(100, tt.att.Data.CommitteeIndex, tt.att.Data.Slot)
		assert.Equal(t, tt.topic, attestationToTopic(subnet, [4]byte{} /* fork digest */), "Wrong topic")
	}
}

func TestService_BroadcastAttestation(t *testing.T) {
	p1 := p2ptest.NewTestP2P(t)
	p2 := p2ptest.NewTestP2P(t)
	p1.Connect(p2)
	if len(p1.BHost.Network().Peers()) == 0 {
		t.Fatal("No peers")
	}

	p := &Service{
		host:                  p1.BHost,
		pubsub:                p1.PubSub(),
		joinedTopics:          map[string]*pubsub.Topic{},
		cfg:                   &Config{},
		genesisTime:           time.Now(),
		genesisValidatorsRoot: bytesutil.PadTo([]byte{'A'}, 32),
		subnetsLock:           make(map[uint64]*sync.RWMutex),
		subnetsLockLock:       sync.Mutex{},
		peers: peers.NewStatus(t.Context(), &peers.StatusConfig{
			ScorerParams: &scorers.Config{},
		}),
	}

	msg := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.NewBitlist(7)})
	subnet := uint64(5)

	topic := AttestationSubnetTopicFormat
	GossipTypeMapping[reflect.TypeOf(msg)] = topic
	digest, err := p.currentForkDigest()
	require.NoError(t, err)
	topic = fmt.Sprintf(topic, digest, subnet)

	// External peer subscribes to the topic.
	topic += p.Encoding().ProtocolSuffix()
	sub, err := p2.SubscribeToTopic(topic)
	require.NoError(t, err)

	time.Sleep(50 * time.Millisecond) // libp2p fails without this delay...

	// Async listen for the pubsub, must be before the broadcast.
	var wg sync.WaitGroup
	wg.Add(1)
	go func(tt *testing.T) {
		defer wg.Done()
		ctx, cancel := context.WithTimeout(t.Context(), 1*time.Second)
		defer cancel()

		incomingMessage, err := sub.Next(ctx)
		require.NoError(t, err)

		result := &ethpb.Attestation{}
		require.NoError(t, p.Encoding().DecodeGossip(incomingMessage.Data, result))
		if !proto.Equal(result, msg) {
			tt.Errorf("Did not receive expected message, got %+v, wanted %+v", result, msg)
		}
	}(t)

	// Attempt to broadcast nil object should fail.
	ctx := t.Context()
	require.ErrorContains(t, "attempted to broadcast nil", p.BroadcastAttestation(ctx, subnet, nil))

	// Broadcast to peers and wait.
	require.NoError(t, p.BroadcastAttestation(ctx, subnet, msg))
	if util.WaitTimeout(&wg, 1*time.Second) {
		t.Error("Failed to receive pubsub within 1s")
	}
}

func TestService_BroadcastAttestationWithDiscoveryAttempts(t *testing.T) {
	const port = uint(2000)

	// Setup bootnode.
	cfg := &Config{PingInterval: testPingInterval}
	cfg.UDPPort = uint(port)
	_, pkey := createAddrAndPrivKey(t)
	ipAddr := net.ParseIP("127.0.0.1")
	genesisTime := time.Now()
	genesisValidatorsRoot := make([]byte, 32)
	s := &Service{
		cfg:                   cfg,
		genesisTime:           genesisTime,
		genesisValidatorsRoot: genesisValidatorsRoot,
	}
	bootListener, err := s.createListener(ipAddr, pkey)
	require.NoError(t, err)
	defer bootListener.Close()

	bootNode := bootListener.Self()
	subnet := uint64(5)

	var listeners []*listenerWrapper
	var hosts []host.Host
	// setup other nodes.
	cfg = &Config{
		Discv5BootStrapAddrs: []string{bootNode.String()},
		MaxPeers:             2,
		PingInterval:         testPingInterval,
	}
	// Setup 2 different hosts
	for i := uint(1); i <= 2; i++ {
		h, pkey, ipAddr := createHost(t, port+i)
		cfg.UDPPort = uint(port + i)
		cfg.TCPPort = uint(port + i)
		if len(listeners) > 0 {
			cfg.Discv5BootStrapAddrs = append(cfg.Discv5BootStrapAddrs, listeners[len(listeners)-1].Self().String())
		}
		s := &Service{
			cfg:                   cfg,
			genesisTime:           genesisTime,
			genesisValidatorsRoot: genesisValidatorsRoot,
		}
		listener, err := s.startDiscoveryV5(ipAddr, pkey)
		// Set for 2nd peer
		if i == 2 {
			s.dv5Listener = listener
			s.metaData = wrapper.WrappedMetadataV0(new(ethpb.MetaDataV0))
			bitV := bitfield.NewBitvector64()
			bitV.SetBitAt(subnet, true)
			s.updateSubnetRecordWithMetadata(bitV)
		}
		assert.NoError(t, err, "Could not start discovery for node")
		listeners = append(listeners, listener)
		hosts = append(hosts, h)
	}
	defer func() {
		// Close down all peers.
		for _, listener := range listeners {
			listener.Close()
		}
	}()

	// close peers upon exit of test
	defer func() {
		for _, h := range hosts {
			if err := h.Close(); err != nil {
				t.Log(err)
			}
		}
	}()

	ps1, err := pubsub.NewGossipSub(t.Context(), hosts[0],
		pubsub.WithMessageSigning(false),
		pubsub.WithStrictSignatureVerification(false),
	)
	require.NoError(t, err)

	ps2, err := pubsub.NewGossipSub(t.Context(), hosts[1],
		pubsub.WithMessageSigning(false),
		pubsub.WithStrictSignatureVerification(false),
	)
	require.NoError(t, err)
	p := &Service{
		host:                  hosts[0],
		ctx:                   t.Context(),
		pubsub:                ps1,
		dv5Listener:           listeners[0],
		joinedTopics:          map[string]*pubsub.Topic{},
		cfg:                   cfg,
		genesisTime:           time.Now(),
		genesisValidatorsRoot: bytesutil.PadTo([]byte{'A'}, 32),
		subnetsLock:           make(map[uint64]*sync.RWMutex),
		subnetsLockLock:       sync.Mutex{},
		peers: peers.NewStatus(t.Context(), &peers.StatusConfig{
			ScorerParams: &scorers.Config{},
		}),
	}

	p2 := &Service{
		host:                  hosts[1],
		ctx:                   t.Context(),
		pubsub:                ps2,
		dv5Listener:           listeners[1],
		joinedTopics:          map[string]*pubsub.Topic{},
		cfg:                   cfg,
		genesisTime:           time.Now(),
		genesisValidatorsRoot: bytesutil.PadTo([]byte{'A'}, 32),
		subnetsLock:           make(map[uint64]*sync.RWMutex),
		subnetsLockLock:       sync.Mutex{},
		peers: peers.NewStatus(t.Context(), &peers.StatusConfig{
			ScorerParams: &scorers.Config{},
		}),
	}
	go p.listenForNewNodes()
	go p2.listenForNewNodes()

	msg := util.HydrateAttestation(&ethpb.Attestation{AggregationBits: bitfield.NewBitlist(7)})
	topic := AttestationSubnetTopicFormat
	GossipTypeMapping[reflect.TypeOf(msg)] = topic
	digest, err := p.currentForkDigest()
	require.NoError(t, err)
	topic = fmt.Sprintf(topic, digest, subnet)

	// External peer subscribes to the topic.
	topic += p.Encoding().ProtocolSuffix()
	// We don't use our internal subscribe method
	// due to using floodsub over here.
	tpHandle, err := p2.JoinTopic(topic)
	require.NoError(t, err)
	sub, err := tpHandle.Subscribe()
	require.NoError(t, err)

	tpHandle, err = p.JoinTopic(topic)
	require.NoError(t, err)
	_, err = tpHandle.Subscribe()
	require.NoError(t, err)

	time.Sleep(500 * time.Millisecond) // libp2p fails without this delay...

	nodePeers := p.pubsub.ListPeers(topic)
	nodePeers2 := p2.pubsub.ListPeers(topic)

	assert.Equal(t, 1, len(nodePeers))
	assert.Equal(t, 1, len(nodePeers2))

	// Async listen for the pubsub, must be before the broadcast.
	var wg sync.WaitGroup
	wg.Add(1)
	go func(tt *testing.T) {
		defer wg.Done()
		ctx, cancel := context.WithTimeout(t.Context(), 4*time.Second)
		defer cancel()

		incomingMessage, err := sub.Next(ctx)
		require.NoError(t, err)

		result := &ethpb.Attestation{}
		require.NoError(t, p.Encoding().DecodeGossip(incomingMessage.Data, result))
		if !proto.Equal(result, msg) {
			tt.Errorf("Did not receive expected message, got %+v, wanted %+v", result, msg)
		}
	}(t)

	// Broadcast to peers and wait.
	require.NoError(t, p.BroadcastAttestation(t.Context(), subnet, msg))
	if util.WaitTimeout(&wg, 4*time.Second) {
		t.Error("Failed to receive pubsub within 4s")
	}
}

func TestService_BroadcastSyncCommittee(t *testing.T) {
	p1 := p2ptest.NewTestP2P(t)
	p2 := p2ptest.NewTestP2P(t)
	p1.Connect(p2)
	if len(p1.BHost.Network().Peers()) == 0 {
		t.Fatal("No peers")
	}

	p := &Service{
		host:                  p1.BHost,
		pubsub:                p1.PubSub(),
		joinedTopics:          map[string]*pubsub.Topic{},
		cfg:                   &Config{},
		genesisTime:           time.Now(),
		genesisValidatorsRoot: bytesutil.PadTo([]byte{'A'}, 32),
		subnetsLock:           make(map[uint64]*sync.RWMutex),
		subnetsLockLock:       sync.Mutex{},
		peers: peers.NewStatus(t.Context(), &peers.StatusConfig{
			ScorerParams: &scorers.Config{},
		}),
	}

	msg := util.HydrateSyncCommittee(&ethpb.SyncCommitteeMessage{})
	subnet := uint64(5)

	topic := SyncCommitteeSubnetTopicFormat
	GossipTypeMapping[reflect.TypeOf(msg)] = topic
	digest, err := p.currentForkDigest()
	require.NoError(t, err)
	topic = fmt.Sprintf(topic, digest, subnet)

	// External peer subscribes to the topic.
	topic += p.Encoding().ProtocolSuffix()
	sub, err := p2.SubscribeToTopic(topic)
	require.NoError(t, err)

	time.Sleep(50 * time.Millisecond) // libp2p fails without this delay...

	// Async listen for the pubsub, must be before the broadcast.
	var wg sync.WaitGroup
	wg.Add(1)
	go func(tt *testing.T) {
		defer wg.Done()
		ctx, cancel := context.WithTimeout(t.Context(), 1*time.Second)
		defer cancel()

		incomingMessage, err := sub.Next(ctx)
		require.NoError(t, err)

		result := &ethpb.SyncCommitteeMessage{}
		require.NoError(t, p.Encoding().DecodeGossip(incomingMessage.Data, result))
		if !proto.Equal(result, msg) {
			tt.Errorf("Did not receive expected message, got %+v, wanted %+v", result, msg)
		}
	}(t)

	// Broadcasting nil should fail.
	ctx := t.Context()
	require.ErrorContains(t, "attempted to broadcast nil", p.BroadcastSyncCommitteeMessage(ctx, subnet, nil))

	// Broadcast to peers and wait.
	require.NoError(t, p.BroadcastSyncCommitteeMessage(ctx, subnet, msg))
	if util.WaitTimeout(&wg, 1*time.Second) {
		t.Error("Failed to receive pubsub within 1s")
	}
}

func TestService_BroadcastBlob(t *testing.T) {
	p1 := p2ptest.NewTestP2P(t)
	p2 := p2ptest.NewTestP2P(t)
	p1.Connect(p2)
	require.NotEqual(t, 0, len(p1.BHost.Network().Peers()), "No peers")

	p := &Service{
		host:                  p1.BHost,
		pubsub:                p1.PubSub(),
		joinedTopics:          map[string]*pubsub.Topic{},
		cfg:                   &Config{},
		genesisTime:           time.Now(),
		genesisValidatorsRoot: bytesutil.PadTo([]byte{'A'}, 32),
		subnetsLock:           make(map[uint64]*sync.RWMutex),
		subnetsLockLock:       sync.Mutex{},
		peers: peers.NewStatus(t.Context(), &peers.StatusConfig{
			ScorerParams: &scorers.Config{},
		}),
	}

	header := util.HydrateSignedBeaconHeader(&ethpb.SignedBeaconBlockHeader{})
	commitmentInclusionProof := make([][]byte, 17)
	for i := range commitmentInclusionProof {
		commitmentInclusionProof[i] = bytesutil.PadTo([]byte{}, 32)
	}
	blobSidecar := &ethpb.BlobSidecar{
		Index:                    1,
		Blob:                     bytesutil.PadTo([]byte{'C'}, fieldparams.BlobLength),
		KzgCommitment:            bytesutil.PadTo([]byte{'D'}, fieldparams.BLSPubkeyLength),
		KzgProof:                 bytesutil.PadTo([]byte{'E'}, fieldparams.BLSPubkeyLength),
		SignedBlockHeader:        header,
		CommitmentInclusionProof: commitmentInclusionProof,
	}
	subnet := uint64(0)

	topic := BlobSubnetTopicFormat
	GossipTypeMapping[reflect.TypeOf(blobSidecar)] = topic
	digest, err := p.currentForkDigest()
	require.NoError(t, err)
	topic = fmt.Sprintf(topic, digest, subnet)

	// External peer subscribes to the topic.
	topic += p.Encoding().ProtocolSuffix()
	sub, err := p2.SubscribeToTopic(topic)
	require.NoError(t, err)

	time.Sleep(50 * time.Millisecond) // libp2p fails without this delay...

	// Async listen for the pubsub, must be before the broadcast.
	var wg sync.WaitGroup
	wg.Add(1)
	go func(tt *testing.T) {
		defer wg.Done()
		ctx, cancel := context.WithTimeout(t.Context(), 1*time.Second)
		defer cancel()

		incomingMessage, err := sub.Next(ctx)
		require.NoError(t, err)

		result := &ethpb.BlobSidecar{}
		require.NoError(t, p.Encoding().DecodeGossip(incomingMessage.Data, result))
		require.DeepEqual(t, result, blobSidecar)
	}(t)

	// Attempt to broadcast nil object should fail.
	ctx := t.Context()
	require.ErrorContains(t, "attempted to broadcast nil", p.BroadcastBlob(ctx, subnet, nil))

	// Broadcast to peers and wait.
	require.NoError(t, p.BroadcastBlob(ctx, subnet, blobSidecar))
	require.Equal(t, false, util.WaitTimeout(&wg, 1*time.Second), "Failed to receive pubsub within 1s")
}

func TestService_BroadcastLightClientOptimisticUpdate(t *testing.T) {
	p1 := p2ptest.NewTestP2P(t)
	p2 := p2ptest.NewTestP2P(t)
	p1.Connect(p2)
	require.NotEqual(t, 0, len(p1.BHost.Network().Peers()))

	p := &Service{
		host:                  p1.BHost,
		pubsub:                p1.PubSub(),
		joinedTopics:          map[string]*pubsub.Topic{},
		cfg:                   &Config{},
		genesisTime:           time.Now(),
		genesisValidatorsRoot: bytesutil.PadTo([]byte{'A'}, 32),
		subnetsLock:           make(map[uint64]*sync.RWMutex),
		subnetsLockLock:       sync.Mutex{},
		peers: peers.NewStatus(t.Context(), &peers.StatusConfig{
			ScorerParams: &scorers.Config{},
		}),
	}

	l := util.NewTestLightClient(t, version.Altair)
	msg, err := lightClient.NewLightClientOptimisticUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock)
	require.NoError(t, err)

	GossipTypeMapping[reflect.TypeOf(msg)] = LightClientOptimisticUpdateTopicFormat
	digest, err := forks.ForkDigestFromEpoch(slots.ToEpoch(msg.AttestedHeader().Beacon().Slot), p.genesisValidatorsRoot)
	require.NoError(t, err)
	topic := fmt.Sprintf(LightClientOptimisticUpdateTopicFormat, digest)

	// External peer subscribes to the topic.
	topic += p.Encoding().ProtocolSuffix()
	sub, err := p2.SubscribeToTopic(topic)
	require.NoError(t, err)

	time.Sleep(50 * time.Millisecond) // libp2p fails without this delay...

	// Async listen for the pubsub, must be before the broadcast.
	var wg sync.WaitGroup
	wg.Add(1)
	go func(tt *testing.T) {
		defer wg.Done()
		ctx, cancel := context.WithTimeout(t.Context(), 1*time.Second)
		defer cancel()

		incomingMessage, err := sub.Next(ctx)
		require.NoError(t, err)

		result := &ethpb.LightClientOptimisticUpdateAltair{}
		require.NoError(t, p.Encoding().DecodeGossip(incomingMessage.Data, result))
		if !proto.Equal(result, msg.Proto()) {
			tt.Errorf("Did not receive expected message, got %+v, wanted %+v", result, msg)
		}
	}(t)

	// Broadcasting nil should fail.
	ctx := t.Context()
	require.ErrorContains(t, "attempted to broadcast nil", p.BroadcastLightClientOptimisticUpdate(ctx, nil))
	var nilUpdate interfaces.LightClientOptimisticUpdate
	require.ErrorContains(t, "attempted to broadcast nil", p.BroadcastLightClientOptimisticUpdate(ctx, nilUpdate))

	// Broadcast to peers and wait.
	require.NoError(t, p.BroadcastLightClientOptimisticUpdate(ctx, msg))
	if util.WaitTimeout(&wg, 1*time.Second) {
		t.Error("Failed to receive pubsub within 1s")
	}
}

func TestService_BroadcastLightClientFinalityUpdate(t *testing.T) {
	p1 := p2ptest.NewTestP2P(t)
	p2 := p2ptest.NewTestP2P(t)
	p1.Connect(p2)
	require.NotEqual(t, 0, len(p1.BHost.Network().Peers()))

	p := &Service{
		host:                  p1.BHost,
		pubsub:                p1.PubSub(),
		joinedTopics:          map[string]*pubsub.Topic{},
		cfg:                   &Config{},
		genesisTime:           time.Now(),
		genesisValidatorsRoot: bytesutil.PadTo([]byte{'A'}, 32),
		subnetsLock:           make(map[uint64]*sync.RWMutex),
		subnetsLockLock:       sync.Mutex{},
		peers: peers.NewStatus(t.Context(), &peers.StatusConfig{
			ScorerParams: &scorers.Config{},
		}),
	}

	l := util.NewTestLightClient(t, version.Altair)
	msg, err := lightClient.NewLightClientFinalityUpdateFromBeaconState(l.Ctx, l.State.Slot(), l.State, l.Block, l.AttestedState, l.AttestedBlock, l.FinalizedBlock)
	require.NoError(t, err)

	GossipTypeMapping[reflect.TypeOf(msg)] = LightClientFinalityUpdateTopicFormat
	digest, err := forks.ForkDigestFromEpoch(slots.ToEpoch(msg.AttestedHeader().Beacon().Slot), p.genesisValidatorsRoot)
	require.NoError(t, err)
	topic := fmt.Sprintf(LightClientFinalityUpdateTopicFormat, digest)

	// External peer subscribes to the topic.
	topic += p.Encoding().ProtocolSuffix()
	sub, err := p2.SubscribeToTopic(topic)
	require.NoError(t, err)

	time.Sleep(50 * time.Millisecond) // libp2p fails without this delay...

	// Async listen for the pubsub, must be before the broadcast.
	var wg sync.WaitGroup
	wg.Add(1)
	go func(tt *testing.T) {
		defer wg.Done()
		ctx, cancel := context.WithTimeout(t.Context(), 1*time.Second)
		defer cancel()

		incomingMessage, err := sub.Next(ctx)
		require.NoError(t, err)

		result := &ethpb.LightClientFinalityUpdateAltair{}
		require.NoError(t, p.Encoding().DecodeGossip(incomingMessage.Data, result))
		if !proto.Equal(result, msg.Proto()) {
			tt.Errorf("Did not receive expected message, got %+v, wanted %+v", result, msg)
		}
	}(t)

	// Broadcasting nil should fail.
	ctx := t.Context()
	require.ErrorContains(t, "attempted to broadcast nil", p.BroadcastLightClientFinalityUpdate(ctx, nil))
	var nilUpdate interfaces.LightClientFinalityUpdate
	require.ErrorContains(t, "attempted to broadcast nil", p.BroadcastLightClientFinalityUpdate(ctx, nilUpdate))

	// Broadcast to peers and wait.
	require.NoError(t, p.BroadcastLightClientFinalityUpdate(ctx, msg))
	if util.WaitTimeout(&wg, 1*time.Second) {
		t.Error("Failed to receive pubsub within 1s")
	}
}

func TestService_BroadcastDataColumn(t *testing.T) {
	const (
		port        = 2000
		columnIndex = 12
		topicFormat = DataColumnSubnetTopicFormat
	)

	// Load the KZG trust setup.
	err := kzg.Start()
	require.NoError(t, err)

	gFlags := new(flags.GlobalFlags)
	gFlags.MinimumPeersPerSubnet = 1
	flags.Init(gFlags)

	// Reset config.
	defer flags.Init(new(flags.GlobalFlags))

	// Create two peers and connect them.
	p1, p2 := p2ptest.NewTestP2P(t), p2ptest.NewTestP2P(t)
	p1.Connect(p2)

	// Test the peers are connected.
	require.NotEqual(t, 0, len(p1.BHost.Network().Peers()), "No peers")

	// Create a host.
	_, pkey, ipAddr := createHost(t, port)

	service := &Service{
		ctx:                   t.Context(),
		host:                  p1.BHost,
		pubsub:                p1.PubSub(),
		joinedTopics:          map[string]*pubsub.Topic{},
		cfg:                   &Config{},
		genesisTime:           time.Now(),
		genesisValidatorsRoot: bytesutil.PadTo([]byte{'A'}, 32),
		subnetsLock:           make(map[uint64]*sync.RWMutex),
		subnetsLockLock:       sync.Mutex{},
		peers:                 peers.NewStatus(t.Context(), &peers.StatusConfig{ScorerParams: &scorers.Config{}}),
	}

	// Create a listener.
	listener, err := service.startDiscoveryV5(ipAddr, pkey)
	require.NoError(t, err)

	service.dv5Listener = listener

	digest, err := service.currentForkDigest()
	require.NoError(t, err)

	subnet := peerdas.ComputeSubnetForDataColumnSidecar(columnIndex)
	topic := fmt.Sprintf(topicFormat, digest, subnet) + service.Encoding().ProtocolSuffix()

	roSidecars, _ := util.CreateTestVerifiedRoDataColumnSidecars(t, []util.DataColumnParam{{Index: columnIndex}})
	sidecar := roSidecars[0].DataColumnSidecar

	// Attempt to broadcast nil object should fail.
	var emptyRoot [fieldparams.RootLength]byte
	err = service.BroadcastDataColumn(emptyRoot, subnet, nil)
	require.ErrorContains(t, "attempted to broadcast nil", err)

	// Subscribe to the topic.
	sub, err := p2.SubscribeToTopic(topic)
	require.NoError(t, err)

	// libp2p fails without this delay
	time.Sleep(50 * time.Millisecond)

	// Broadcast to peers and wait.
	err = service.BroadcastDataColumn(emptyRoot, subnet, sidecar)
	require.NoError(t, err)

	// Receive the message.
	ctx, cancel := context.WithTimeout(t.Context(), 5*time.Second)
	defer cancel()

	msg, err := sub.Next(ctx)
	require.NoError(t, err)

	var result ethpb.DataColumnSidecar
	require.NoError(t, service.Encoding().DecodeGossip(msg.Data, &result))
	require.DeepEqual(t, &result, sidecar)
}