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 +257,42 @@ func initPrivateKey(path string) (p2pcrypto.PrivKey, error) {
 	return nil, err
 }
 
+func initNetworkId(networkID int, db *meshdb.MeshDB) error {
+	// see if there is already a stored networkID
+	snapshot, err := db.Metadata.GetSnapshot()
+	if err != nil {
+		return err
+	}
+
+	filter := db.Metadata.EthereumNetworkIDIndex.All()
+	var metadataCol []*meshdb.Metadata
+	err = snapshot.NewQuery(filter).Run(&metadataCol)
+	if err != nil {
+		return err
+	}
+
+	switch len(metadataCol) {
+	case 1:
+		// on subsequent startups, verify we are on the same network
+		loadedNetworkID := metadataCol[0].EthereumNetworkID.Int64()
+		if loadedNetworkID != int64(networkID) {
+			log.Error("Mesh previously started on different Ethereum network; switch networks or remove DB")
+			return fmt.Errorf("expected networkID to be '%v', got '%v'", networkID, loadedNetworkID)
+		}
+		return nil
+	case 0:
+		// if this is the first startup, set the networkId in initial metadata
+		setMetadata := meshdb.Metadata{EthereumNetworkID: big.NewInt(int64(networkID))}
+		err = db.Metadata.Insert(&setMetadata)
+		if err != nil {
+			return err
+		}
+		return nil
+	default:
+		return fmt.Errorf("Detected more than one 'Metadata' collection (%v); should be one or zero", len(metadataCol))
+	}
+}
+
 func (app *App) Start() error {
 	go func() {
 		err := app.node.Start()

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("metadata")
+}
+
 // 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 +78,12 @@ type OrdersCollection struct {
 	IsRemovedIndex                       *db.Index
 }
 
+// MetadataCollection represents a DB collection used to store instance metadata
+type MetadataCollection struct {
+	*db.Collection
+	EthereumNetworkIDIndex *db.Index
+}
+
 // NewMeshDB instantiates a new MeshDB instance
 func NewMeshDB(path string) (*MeshDB, error) {
 	database, err := db.Open(path)
@@ -84,10 +101,16 @@ 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 +193,21 @@ 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
+	}
+	ethereumNetworkIDIndex := col.AddIndex("ethereumNetworkID", func(m db.Model) []byte {
+		networkID := m.(*Metadata).EthereumNetworkID
+		return networkID.Bytes()
+	})
+	return &MetadataCollection{
+		Collection:             col,
+		EthereumNetworkIDIndex: ethereumNetworkIDIndex,
+	}, nil
+}
+
 // Close closes the database connection
 func (m *MeshDB) Close() {
 	m.database.Close()