From eced4f5de4b1be91f14127b4c82c6124bd3acec5 Mon Sep 17 00:00:00 2001
From: Josh Klopfenstein <git@joshklop.com>
Date: Tue, 28 Nov 2023 16:58:12 -0600
Subject: [PATCH] Validate the --network option

---
 node/node.go      | 14 ++++++++++++++
 node/node_test.go | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)

diff --git a/node/node.go b/node/node.go
index d6d3369f19..ab96b521b0 100644
--- a/node/node.go
+++ b/node/node.go
@@ -13,6 +13,7 @@ import (
 	"github.com/NethermindEth/juno/blockchain"
 	"github.com/NethermindEth/juno/clients/feeder"
 	"github.com/NethermindEth/juno/clients/gateway"
+	"github.com/NethermindEth/juno/core"
 	"github.com/NethermindEth/juno/db"
 	"github.com/NethermindEth/juno/db/pebble"
 	"github.com/NethermindEth/juno/db/remote"
@@ -120,6 +121,19 @@ func New(cfg *Config, version string) (*Node, error) { //nolint:gocyclo,funlen
 	services := make([]service.Service, 0)
 
 	chain := blockchain.New(database, cfg.Network, log)
+
+	// Verify that cfg.Network is compatible with the database.
+	head, err := chain.Head()
+	if err != nil && !errors.Is(err, db.ErrKeyNotFound) {
+		return nil, fmt.Errorf("get head block from database: %v", err)
+	}
+	if head != nil {
+		// We assume that there is at least one transaction in the block or that it is a pre-0.7 block.
+		if _, err = core.VerifyBlockHash(head, cfg.Network); err != nil {
+			return nil, errors.New("unable to verify latest block hash; are the database and --network option compatible?")
+		}
+	}
+
 	feederClientTimeout := 5 * time.Second
 	client := feeder.NewClient(cfg.Network.FeederURL()).WithUserAgent(ua).WithLogger(log).
 		WithTimeout(feederClientTimeout).WithAPIKey(cfg.GatewayAPIKey)
diff --git a/node/node_test.go b/node/node_test.go
index 31c677c4dd..7cebf7add8 100644
--- a/node/node_test.go
+++ b/node/node_test.go
@@ -5,7 +5,12 @@ import (
 	"testing"
 	"time"
 
+	"github.com/NethermindEth/juno/blockchain"
+	"github.com/NethermindEth/juno/clients/feeder"
+	"github.com/NethermindEth/juno/db/pebble"
 	"github.com/NethermindEth/juno/node"
+	adaptfeeder "github.com/NethermindEth/juno/starknetdata/feeder"
+	"github.com/NethermindEth/juno/sync"
 	"github.com/NethermindEth/juno/utils"
 	"github.com/stretchr/testify/require"
 )
@@ -41,3 +46,45 @@ func TestNewNode(t *testing.T) {
 	cancel()
 	n.Run(ctx)
 }
+
+func TestNetworkVerificationOnNonEmptyDB(t *testing.T) {
+	network := utils.Integration
+	tests := map[string]struct {
+		network   utils.Network
+		errString string
+	}{
+		"same network": {
+			network:   network,
+			errString: "",
+		},
+		"different network": {
+			network:   utils.Mainnet,
+			errString: "unable to verify latest block hash; are the database and --network option compatible?",
+		},
+	}
+
+	for description, test := range tests {
+		t.Run(description, func(t *testing.T) {
+			dbPath := t.TempDir()
+			log := utils.NewNopZapLogger()
+			database, err := pebble.New(dbPath, 1, log)
+			require.NoError(t, err)
+			chain := blockchain.New(database, network, log)
+			syncer := sync.New(chain, adaptfeeder.New(feeder.NewTestClient(t, network)), log, 0, false)
+			ctx, cancel := context.WithTimeout(context.Background(), 250*time.Millisecond)
+			require.NoError(t, syncer.Run(ctx))
+			cancel()
+			require.NoError(t, database.Close())
+
+			_, err = node.New(&node.Config{
+				DatabasePath: dbPath,
+				Network:      test.network,
+			}, "v0.1")
+			if test.errString == "" {
+				require.NoError(t, err)
+			} else {
+				require.ErrorContains(t, err, test.errString)
+			}
+		})
+	}
+}