op-node: Extract contract binding for SystemConfig (#11227)

op-node/cmd/genesis/cmd.go

@@ -4,12 +4,10 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"math/big"
 
+	"github.com/ethereum-optimism/optimism/op-service/sources/batching"
 	"github.com/urfave/cli/v2"
 
-	"github.com/ethereum/go-ethereum"
-	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/ethereum/go-ethereum/log"
 
@@ -165,18 +163,12 @@ var Subcommands = cli.Commands{
 				return fmt.Errorf("cannot dial %s: %w", l1RPC, err)
 			}
 
-			funcDef := "startBlock()"
-			funcHash := crypto.Keccak256Hash([]byte(funcDef))
-			msg := ethereum.CallMsg{
-				To:   &config.SystemConfigProxy,
-				Data: funcHash[:4], // hardcode the 4byte sig
-			}
-			result, err := client.CallContract(context.Background(), msg, nil)
+			caller := batching.NewMultiCaller(client.Client(), batching.DefaultBatchSize)
+			sysCfg := NewSystemConfigContract(caller, config.SystemConfigProxy)
+			l1StartBlockNum, err := sysCfg.StartBlock(context.Background())
 			if err != nil {
-				return fmt.Errorf("failed to fetch startBlock from SystemConfig contract: %w", err)
+				return fmt.Errorf("failed to fetch startBlock from SystemConfig: %w", err)
 			}
-
-			l1StartBlockNum := new(big.Int).SetBytes(result)
 			l1StartBlock, err := client.BlockByNumber(context.Background(), l1StartBlockNum)
 			if err != nil {
 				return fmt.Errorf("cannot fetch block by number: %w", err)

op-node/cmd/genesis/systemconfig.go

+package genesis
+
+import (
+	"context"
+	"fmt"
+	"math/big"
+
+	"github.com/ethereum-optimism/optimism/op-service/sources/batching"
+	"github.com/ethereum-optimism/optimism/op-service/sources/batching/rpcblock"
+	"github.com/ethereum-optimism/optimism/packages/contracts-bedrock/snapshots"
+	"github.com/ethereum/go-ethereum/common"
+)
+
+var (
+	methodStartBlock = "startBlock"
+)
+
+type SystemConfigContract struct {
+	caller   *batching.MultiCaller
+	contract *batching.BoundContract
+}
+
+func NewSystemConfigContract(caller *batching.MultiCaller, addr common.Address) *SystemConfigContract {
+	return &SystemConfigContract{
+		caller:   caller,
+		contract: batching.NewBoundContract(snapshots.LoadSystemConfigABI(), addr),
+	}
+}
+
+func (c *SystemConfigContract) StartBlock(ctx context.Context) (*big.Int, error) {
+	result, err := c.caller.SingleCall(ctx, rpcblock.Latest, c.contract.Call(methodStartBlock))
+	if err != nil {
+		return nil, fmt.Errorf("failed to call startBlock: %w", err)
+	}
+	return result.GetBigInt(0), nil
+}

op-node/cmd/genesis/systemconfig_test.go

+package genesis
+
+import (
+	"context"
+	"math/big"
+	"testing"
+
+	"github.com/ethereum-optimism/optimism/op-service/sources/batching"
+	"github.com/ethereum-optimism/optimism/op-service/sources/batching/rpcblock"
+	batchingTest "github.com/ethereum-optimism/optimism/op-service/sources/batching/test"
+	"github.com/ethereum-optimism/optimism/packages/contracts-bedrock/snapshots"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSystemConfigContract_StartBlock(t *testing.T) {
+	addr := common.Address{0xaa}
+	sysCfgAbi := snapshots.LoadSystemConfigABI()
+	stubRpc := batchingTest.NewAbiBasedRpc(t, addr, sysCfgAbi)
+	caller := batching.NewMultiCaller(stubRpc, batching.DefaultBatchSize)
+	sysCfg := NewSystemConfigContract(caller, addr)
+	expected := big.NewInt(56)
+	stubRpc.SetResponse(addr, methodStartBlock, rpcblock.Latest, nil, []interface{}{expected})
+
+	result, err := sysCfg.StartBlock(context.Background())
+	require.NoError(t, err)
+	require.Truef(t, result.Cmp(expected) == 0, "expected %v, got %v", expected, result)
+}

packages/contracts-bedrock/snapshots/abi_loader.go

@@ -22,6 +22,9 @@ var mips []byte
 //go:embed abi/DelayedWETH.json
 var delayedWETH []byte
 
+//go:embed abi/SystemConfig.json
+var systemConfig []byte
+
 func LoadDisputeGameFactoryABI() *abi.ABI {
 	return loadABI(disputeGameFactory)
 }
@@ -38,6 +41,10 @@ func LoadDelayedWETHABI() *abi.ABI {
 	return loadABI(delayedWETH)
 }
 
+func LoadSystemConfigABI() *abi.ABI {
+	return loadABI(systemConfig)
+}
+
 func loadABI(json []byte) *abi.ABI {
 	if parsed, err := abi.JSON(bytes.NewReader(json)); err != nil {
 		panic(err)