core: implement network ID detection check on startup

core/core.go

@@ -7,6 +7,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"math/big"
 	"os"
 	"path/filepath"
 	"sync"
@@ -119,6 +120,12 @@ func New(config Config) (*App, error) {
 		return nil, err
 	}
 
+	// Check if the DB has been previously intialized with a different networkId
+	err = initNetworkId(config.EthereumNetworkID, meshDB)
+	if err != nil {
+		return nil, err
+	}
+
 	// Initialize the ETH client, which will be used by various watchers.
 	ethClient, err := ethclient.Dial(config.EthereumRPCURL)
 	if err != nil {
@@ -250,6 +257,32 @@ func initPrivateKey(path string) (p2pcrypto.PrivKey, error) {
 	return nil, err
 }
 
+func initNetworkId(networkID int, meshDB *meshdb.MeshDB) error {
+	var metadata meshdb.Metadata
+	err := meshDB.Metadata.FindByID([]byte{0}, &metadata)
+
+	if _, ok := err.(db.NotFoundError); ok {
+		// No stored metadata found (first startup)
+		setMetadata := meshdb.Metadata{EthereumNetworkID: big.NewInt(int64(networkID))}
+		err = meshDB.Metadata.Insert(&setMetadata)
+		if err != nil {
+			return err
+		}
+		return nil
+	} else if err != nil {
+		return err
+	}
+
+	// on subsequent startups, verify we are on the same network
+	loadedNetworkID := metadata.EthereumNetworkID.Int64()
+	if loadedNetworkID != int64(networkID) {
+		err := fmt.Errorf("expected networkID to be %d but got %d", loadedNetworkID, networkID)
+		log.WithError(err).Error("Mesh previously started on different Ethereum network; switch networks or remove DB")
+		return err
+	}
+	return nil
+}
+
 func (app *App) Start() error {
 	go func() {
 		err := app.node.Start()

core/core_test.go

@@ -0,0 +1,28 @@
+package core
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/0xProject/0x-mesh/meshdb"
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/require"
+)
+
+func TestEthereumNetworkDetection(t *testing.T) {
+	meshDB, err := meshdb.NewMeshDB("/tmp/meshdb_testing/" + uuid.New().String())
+	require.NoError(t, err)
+
+	// simulate starting up on mainnet
+	err = initNetworkId(1, meshDB)
+	require.NoError(t, err)
+
+	// simulate restart on same network
+	err = initNetworkId(1, meshDB)
+	require.NoError(t, err)
+
+	// should error when attempting to start on different network
+	err = initNetworkId(2, meshDB)
+	assert.Error(t, err)
+}

meshdb/meshdb.go

@@ -45,11 +45,22 @@ func (o Order) ID() []byte {
 	return o.Hash.Bytes()
 }
 
+// Metadata is the database representation of MeshDB instance metadata
+type Metadata struct {
+	EthereumNetworkID *big.Int
+}
+
+// ID returns the id used for the metadata collection (one per DB)
+func (m Metadata) ID() []byte {
+	return []byte{0}
+}
+
 // MeshDB instantiates the DB connection and creates all the collections used by the application
 type MeshDB struct {
 	database    *db.DB
 	MiniHeaders *MiniHeadersCollection
 	Orders      *OrdersCollection
+	Metadata    *MetadataCollection
 }
 
 // MiniHeadersCollection represents a DB collection of mini Ethereum block headers
@@ -67,6 +78,11 @@ type OrdersCollection struct {
 	IsRemovedIndex                       *db.Index
 }
 
+// MetadataCollection represents a DB collection used to store instance metadata
+type MetadataCollection struct {
+	*db.Collection
+}
+
 // NewMeshDB instantiates a new MeshDB instance
 func NewMeshDB(path string) (*MeshDB, error) {
 	database, err := db.Open(path)
@@ -84,10 +100,16 @@ func NewMeshDB(path string) (*MeshDB, error) {
 		return nil, err
 	}
 
+	metadata, err := setupMetadata(database)
+	if err != nil {
+		return nil, err
+	}
+
 	return &MeshDB{
 		database:    database,
 		MiniHeaders: miniHeaders,
 		Orders:      orders,
+		Metadata:    metadata,
 	}, nil
 }
 
@@ -170,6 +192,14 @@ func setupMiniHeaders(database *db.DB) (*MiniHeadersCollection, error) {
 	}, nil
 }
 
+func setupMetadata(database *db.DB) (*MetadataCollection, error) {
+	col, err := database.NewCollection("metadata", &Metadata{})
+	if err != nil {
+		return nil, err
+	}
+	return &MetadataCollection{col}, nil
+}
+
 // Close closes the database connection
 func (m *MeshDB) Close() {
 	m.database.Close()