fix(sentry): Derive ethereum network from genesis root (#24)

pkg/sentry/ethereum/metadata.go

@@ -7,7 +7,7 @@ import (
 
 	v1 "github.com/attestantio/go-eth2-client/api/v1"
 	backoff "github.com/cenkalti/backoff/v4"
-	xatuv1 "github.com/ethpandaops/xatu/pkg/proto/eth/v1"
+	xatuethv1 "github.com/ethpandaops/xatu/pkg/proto/eth/v1"
 	"github.com/ethpandaops/xatu/pkg/sentry/ethereum/networks"
 	"github.com/ethpandaops/xatu/pkg/wallclock"
 	"github.com/go-co-op/gocron"
@@ -111,35 +111,18 @@ func (m *MetadataService) Wallclock() *wallclock.EthereumBeaconChain {
 }
 
 func (m *MetadataService) DeriveNetworkName(ctx context.Context) error {
-	for _, slot := range networks.AllNetworkIdentifierSlots() {
-		// Grab the block that is at the slot.
-		block, err := m.beacon.FetchBlock(ctx, xatuv1.SlotAsString(slot))
-		if err != nil {
-			// A block in that slot might not exist, or the connection to the node may be bad.
-			continue
-		}
-
-		root, err := block.Root()
-		if err != nil {
-			// Invalid block root probably means the slot is empty.
-			continue
-		}
-
-		network := networks.DeriveNetworkName(slot, xatuv1.RootAsString(root))
-		if network == networks.NetworkNameUnknown {
-			// Unknown network. Try the next slot.
-			continue
-		}
-
-		if m.NetworkName == networks.NetworkNameNone {
-			m.log.WithField("network", network).Info("Detected ethereum network")
-		}
+	if m.Genesis == nil {
+		return errors.New("genesis is not available")
+	}
 
-		m.NetworkName = network
+	network := networks.DeriveNetworkName(xatuethv1.RootAsString(m.Genesis.GenesisValidatorsRoot))
 
-		break
+	if network != m.NetworkName {
+		m.log.WithField("network", network).Info("Detected ethereum network")
 	}
 
+	m.NetworkName = network
+
 	return nil
 }
 

pkg/sentry/ethereum/networks/network.go

@@ -1,7 +1,5 @@
 package networks
 
-import "github.com/attestantio/go-eth2-client/spec/phase0"
-
 type NetworkName string
 
 var (
@@ -12,51 +10,15 @@ var (
 	NetworkNameGoerli  NetworkName = "goerli"
 )
 
-type NetworkIdentifierSlot struct {
-	NetworkName NetworkName
-	Slot        phase0.Slot
-	BlockRoot   string
-}
-
-var NetworkSlotBlockRoots = []NetworkIdentifierSlot{
-	{
-		NetworkName: NetworkNameMainnet,
-		Slot:        phase0.Slot(50),
-		BlockRoot:   "0x68937f266e8f339e3d605b00424446f8db835a4f2548636a906095babc5fb308",
-	},
-	{
-		NetworkName: NetworkNameSepolia,
-		Slot:        phase0.Slot(50),
-		BlockRoot:   "0x79bed901a63e22bb4dbed9330372bc399ea4d5faec87de916a80410135f3475c",
-	},
-	{
-		NetworkName: NetworkNameGoerli,
-		Slot:        phase0.Slot(50),
-		BlockRoot:   "0x93379731ee4c8e438a2c74c850e80fa7b2ccab4d9e25e6dc5567d3a33059b4d4",
-	},
-}
-
-func AllNetworkIdentifierSlots() []phase0.Slot {
-	// Deduplicate the slots.
-	slots := map[phase0.Slot]struct{}{}
-
-	for _, networkSlotBlockRoot := range NetworkSlotBlockRoots {
-		slots[networkSlotBlockRoot.Slot] = struct{}{}
-	}
-
-	slotsSlice := make([]phase0.Slot, 0, len(slots))
-	for slot := range slots {
-		slotsSlice = append(slotsSlice, slot)
-	}
-
-	return slotsSlice
+var NetworkGenesisRoots = map[string]NetworkName{
+	"0x043db0d9a83813551ee2f33450d23797757d430911a9320530ad8a0eabc43efb": NetworkNameGoerli,
+	"0x4b363db94e286120d76eb905340fdd4e54bfe9f06bf33ff6cf5ad27f511bfe95": NetworkNameMainnet,
+	"0xd8ea171f3c94aea21ebc42a1ed61052acf3f9209c00e4efbaaddac09ed9b8078": NetworkNameSepolia,
 }
 
-func DeriveNetworkName(slot phase0.Slot, blockRoot string) NetworkName {
-	for _, networkSlotBlockRoot := range NetworkSlotBlockRoots {
-		if networkSlotBlockRoot.Slot == slot && networkSlotBlockRoot.BlockRoot == blockRoot {
-			return networkSlotBlockRoot.NetworkName
-		}
+func DeriveNetworkName(genesisRoot string) NetworkName {
+	if NetworkGenesisRoots[genesisRoot] != "" {
+		return NetworkGenesisRoots[genesisRoot]
 	}
 
 	return NetworkNameUnknown