Refactor: only use debug_traceCall during gas estimation (#168)

Author: hazim-j

pkg/entrypoint/execution/trace.go

@@ -2,43 +2,45 @@ package execution
 
 import (
 	"context"
+	"fmt"
 	"math"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/accounts/abi/bind"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/ethclient"
-	"github.com/ethereum/go-ethereum/rpc"
+	ethRpc "github.com/ethereum/go-ethereum/rpc"
 	"github.com/stackup-wallet/stackup-bundler/pkg/entrypoint"
+	"github.com/stackup-wallet/stackup-bundler/pkg/entrypoint/reverts"
 	"github.com/stackup-wallet/stackup-bundler/pkg/entrypoint/utils"
 	"github.com/stackup-wallet/stackup-bundler/pkg/errors"
 	"github.com/stackup-wallet/stackup-bundler/pkg/tracer"
 	"github.com/stackup-wallet/stackup-bundler/pkg/userop"
 )
 
 func TraceSimulateHandleOp(
-	rpc *rpc.Client,
+	rpc *ethRpc.Client,
 	entryPoint common.Address,
 	op *userop.UserOperation,
 	chainID *big.Int,
 	customTracer string,
 	target common.Address,
 	data []byte,
-) error {
+) (*reverts.ExecutionResultRevert, error) {
 	ep, err := entrypoint.NewEntrypoint(entryPoint, ethclient.NewClient(rpc))
 	if err != nil {
-		return err
+		return nil, err
 	}
 	auth, err := bind.NewKeyedTransactorWithChainID(utils.DummyPk, chainID)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	auth.GasLimit = math.MaxUint64
 	auth.NoSend = true
 	tx, err := ep.SimulateHandleOp(auth, entrypoint.UserOperation(*op), target, data)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	var res tracer.BundlerErrorReturn
@@ -51,24 +53,37 @@ func TraceSimulateHandleOp(
 		Tracer: customTracer,
 	}
 	if err := rpc.CallContext(context.Background(), &res, "debug_traceCall", &req, "latest", &opts); err != nil {
-		return err
+		return nil, err
+	}
+	outErr, err := errors.ParseHexToRpcDataError(res.Output)
+	if err != nil {
+		return nil, err
+	}
+
+	sim, simErr := reverts.NewExecutionResult(outErr)
+	if simErr != nil {
+		fo, foErr := reverts.NewFailedOp(outErr)
+		if foErr != nil {
+			return nil, fmt.Errorf("%s, %s", simErr, foErr)
+		}
+		return nil, errors.NewRPCError(errors.REJECTED_BY_EP_OR_ACCOUNT, fo.Reason, fo)
 	}
 
 	if len(res.Reverts) != 0 {
 		data, err := hexutil.Decode(res.Reverts[len(res.Reverts)-1])
 		if err != nil {
-			return err
+			return sim, err
 		}
 
 		if len(data) == 0 {
-			return errors.NewRPCError(errors.EXECUTION_REVERTED, "execution reverted", nil)
+			return sim, errors.NewRPCError(errors.EXECUTION_REVERTED, "execution reverted", nil)
 		}
 
 		reason, err := errors.DecodeRevert(data)
 		if err != nil {
-			return err
+			return sim, err
 		}
-		return errors.NewRPCError(errors.EXECUTION_REVERTED, reason, reason)
+		return sim, errors.NewRPCError(errors.EXECUTION_REVERTED, reason, reason)
 	}
-	return nil
+	return sim, nil
 }

pkg/errors/string.go

@@ -0,0 +1,29 @@
+package errors
+
+import (
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/rpc"
+)
+
+type hexDataErrorWrapper struct {
+	output string
+}
+
+// ParseHexToRpcDataError is a utility function that converts a hex string into an interface that's compatible
+// with rpc.DataError. This is useful for parsing output from a debug_traceCall that resulted in a transaction
+// revert.
+func ParseHexToRpcDataError(hex string) (rpc.DataError, error) {
+	if _, err := common.ParseHexOrString(hex); err != nil {
+		return nil, err
+	}
+
+	res := &hexDataErrorWrapper{output: hex}
+	return res, nil
+}
+
+func (t *hexDataErrorWrapper) Error() string {
+	return t.output
+}
+func (t *hexDataErrorWrapper) ErrorData() any {
+	return t.output
+}

pkg/gas/estimate.go

@@ -13,9 +13,6 @@ import (
 
 // EstimateGas uses the simulateHandleOp method on the EntryPoint to derive an estimate for
 // verificationGasLimit and callGasLimit.
-//
-// TODO: This function requires an eth_call and a debug_traceCall. It could probably be optimized further by
-// just using a debug_traceCall.
 func EstimateGas(
 	rpc *rpc.Client,
 	from common.Address,
@@ -43,15 +40,11 @@ func EstimateGas(
 		return 0, 0, err
 	}
 
-	sim, err := execution.SimulateHandleOp(rpc, from, simOp, common.Address{}, []byte{})
+	sim, err := execution.TraceSimulateHandleOp(rpc, from, simOp, chainID, tracer, common.Address{}, []byte{})
 	if err != nil {
 		return 0, 0, err
 	}
 
-	if err := execution.TraceSimulateHandleOp(rpc, from, op, chainID, tracer, common.Address{}, []byte{}); err != nil {
-		return 0, 0, err
-	}
-
 	tg := big.NewInt(0).Div(sim.Paid, op.MaxFeePerGas)
 	cgl := big.NewInt(0).Add(big.NewInt(0).Sub(tg, sim.PreOpGas), big.NewInt(int64(ov.fixed)))
 	min := ov.NonZeroValueCall()

pkg/tracer/BundlerErrorTracer.js

@@ -6,6 +6,7 @@ var tracer = {
   result: function result(ctx, db) {
     return {
       reverts: this.reverts,
+      output: toHex(ctx.output),
     };
   },
 

pkg/tracer/types.go

@@ -57,4 +57,5 @@ type BundlerCollectorReturn struct {
 // BundlerErrorReturn is the return value from performing an EVM trace with BundlerErrorTracer.js.
 type BundlerErrorReturn struct {
 	Reverts []string `json:"reverts"`
+	Output  string   `json:"output"`
 }