op-node: handle special engine RPC user-input error codes (#3319)

op-node/eth/types.go

@@ -20,9 +20,33 @@ import (
 type ErrorCode int
 
 const (
-	UnavailablePayload ErrorCode = -32001
+	UnknownPayload           ErrorCode = -32001 // Payload does not exist / is not available.
+	InvalidForkchoiceState   ErrorCode = -38002 // Forkchoice state is invalid / inconsistent.
+	InvalidPayloadAttributes ErrorCode = -38003 // Payload attributes are invalid / inconsistent.
 )
 
+// InputError distinguishes an user-input error from regular rpc errors,
+// to help the (Engine) API user divert from accidental input mistakes.
+type InputError struct {
+	Inner error
+	Code  ErrorCode
+}
+
+func (ie InputError) Error() string {
+	return fmt.Sprintf("input error %d: %s", ie.Code, ie.Inner.Error())
+}
+
+func (ie InputError) Unwrap() error {
+	return ie.Inner
+}
+
+// Is checks if the error is the given target type.
+// Any type of InputError counts, regardless of code.
+func (ie InputError) Is(target error) bool {
+	_, ok := target.(InputError)
+	return ok // we implement Unwrap, so we do not have to check the inner type now
+}
+
 type Bytes32 [32]byte
 
 func (b *Bytes32) UnmarshalJSON(text []byte) error {

op-node/eth/types_test.go

+package eth
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestInputError(t *testing.T) {
+	err := InputError{
+		Inner: errors.New("test error"),
+		Code:  InvalidForkchoiceState,
+	}
+	var x InputError
+	if !errors.As(err, &x) {
+		t.Fatalf("need InputError to be detected as such")
+	}
+	require.ErrorIs(t, err, InputError{}, "need to detect input error with errors.Is")
+}

op-node/rollup/derive/engine_queue.go

@@ -2,6 +2,7 @@ package derive
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"time"
@@ -163,7 +164,17 @@ func (eq *EngineQueue) tryNextUnsafePayload(ctx context.Context) error {
 	}
 	fcRes, err := eq.engine.ForkchoiceUpdate(ctx, &fc, nil)
 	if err != nil {
-		return NewTemporaryError(fmt.Errorf("failed to update forkchoice to prepare for new unsafe payload: %v", err))
+		var inputErr eth.InputError
+		if errors.As(err, &inputErr) {
+			switch inputErr.Code {
+			case eth.InvalidForkchoiceState:
+				return NewResetError(fmt.Errorf("pre-unsafe-block forkchoice update was inconsistent with engine, need reset to resolve: %w", inputErr.Unwrap()))
+			default:
+				return NewTemporaryError(fmt.Errorf("unexpected error code in forkchoice-updated response: %w", err))
+			}
+		} else {
+			return NewTemporaryError(fmt.Errorf("failed to update forkchoice to prepare for new unsafe payload: %w", err))
+		}
 	}
 	if fcRes.PayloadStatus.Status != eth.ExecutionValid {
 		eq.unsafePayloads = eq.unsafePayloads[1:]
@@ -238,13 +249,16 @@ func (eq *EngineQueue) forceNextSafeAttributes(ctx context.Context) error {
 		FinalizedBlockHash: eq.finalized.Hash,
 	}
 	attrs := eq.safeAttributes[0]
-	payload, rpcErr, payloadErr := InsertHeadBlock(ctx, eq.log, eq.engine, fc, attrs, true)
-	if rpcErr != nil {
+	payload, errType, err := InsertHeadBlock(ctx, eq.log, eq.engine, fc, attrs, true)
+	if err != nil {
+		switch errType {
+		case BlockInsertTemporaryErr:
 			// RPC errors are recoverable, we can retry the buffered payload attributes later.
-		return NewTemporaryError(fmt.Errorf("failed to insert new block: %v", rpcErr))
-	}
-	if payloadErr != nil {
-		eq.log.Warn("could not process payload derived from L1 data", "err", payloadErr)
+			return NewTemporaryError(fmt.Errorf("temporarily cannot insert new safe block: %w", err))
+		case BlockInsertPrestateErr:
+			return NewResetError(fmt.Errorf("need reset to resolve pre-state problem: %w", err))
+		case BlockInsertPayloadErr:
+			eq.log.Warn("could not process payload derived from L1 data", "err", err)
 			// filter everything but the deposits
 			var deposits []hexutil.Bytes
 			for _, tx := range attrs.Transactions {
@@ -258,7 +272,10 @@ func (eq *EngineQueue) forceNextSafeAttributes(ctx context.Context) error {
 				eq.safeAttributes[0].Transactions = deposits
 				return nil
 			}
-		return NewCriticalError(fmt.Errorf("failed to process block with only deposit transactions: %w", payloadErr))
+			return NewCriticalError(fmt.Errorf("failed to process block with only deposit transactions: %w", err))
+		default:
+			return NewCriticalError(fmt.Errorf("unknown InsertHeadBlock error type %d: %w", errType, err))
+		}
 	}
 	ref, err := PayloadToBlockRef(payload, &eq.cfg.Genesis)
 	if err != nil {

op-node/rollup/derive/engine_update.go

@@ -65,43 +65,69 @@ func sanityCheckPayload(payload *eth.ExecutionPayload) error {
 	return nil
 }
 
+type BlockInsertionErrType uint
+
+const (
+	BlockInsertOK BlockInsertionErrType = iota
+	BlockInsertTemporaryErr
+	BlockInsertPrestateErr
+	BlockInsertPayloadErr
+)
+
 // InsertHeadBlock creates, executes, and inserts the specified block as the head block.
 // It first uses the given FC to start the block creation process and then after the payload is executed,
 // sets the FC to the same safe and finalized hashes, but updates the head hash to the new block.
 // If updateSafe is true, the head block is considered to be the safe head as well as the head.
 // It returns the payload, an RPC error (if the payload might still be valid), and a payload error (if the payload was not valid)
-func InsertHeadBlock(ctx context.Context, log log.Logger, eng Engine, fc eth.ForkchoiceState, attrs *eth.PayloadAttributes, updateSafe bool) (out *eth.ExecutionPayload, rpcErr error, payloadErr error) {
+func InsertHeadBlock(ctx context.Context, log log.Logger, eng Engine, fc eth.ForkchoiceState, attrs *eth.PayloadAttributes, updateSafe bool) (out *eth.ExecutionPayload, errTyp BlockInsertionErrType, err error) {
 	fcRes, err := eng.ForkchoiceUpdate(ctx, &fc, attrs)
 	if err != nil {
-		return nil, fmt.Errorf("failed to create new block via forkchoice: %w", err), nil
+		var inputErr eth.InputError
+		if errors.As(err, &inputErr) {
+			switch inputErr.Code {
+			case eth.InvalidForkchoiceState:
+				return nil, BlockInsertPrestateErr, fmt.Errorf("pre-block-creation forkchoice update was inconsistent with engine, need reset to resolve: %w", inputErr.Unwrap())
+			case eth.InvalidPayloadAttributes:
+				return nil, BlockInsertPayloadErr, fmt.Errorf("payload attributes are not valid, cannot build block: %w", inputErr.Unwrap())
+			default:
+				return nil, BlockInsertPrestateErr, fmt.Errorf("unexpected error code in forkchoice-updated response: %w", err)
 			}
-	if fcRes.PayloadStatus.Status == eth.ExecutionInvalid || fcRes.PayloadStatus.Status == eth.ExecutionInvalidBlockHash {
-		return nil, nil, eth.ForkchoiceUpdateErr(fcRes.PayloadStatus)
+		} else {
+			return nil, BlockInsertTemporaryErr, fmt.Errorf("failed to create new block via forkchoice: %w", err)
 		}
-	if fcRes.PayloadStatus.Status != eth.ExecutionValid {
-		return nil, eth.ForkchoiceUpdateErr(fcRes.PayloadStatus), nil
+	}
+
+	switch fcRes.PayloadStatus.Status {
+	// TODO(proto): snap sync - specify explicit different error type if node is syncing
+	case eth.ExecutionInvalid, eth.ExecutionInvalidBlockHash:
+		return nil, BlockInsertPayloadErr, eth.ForkchoiceUpdateErr(fcRes.PayloadStatus)
+	case eth.ExecutionValid:
+		break
+	default:
+		return nil, BlockInsertTemporaryErr, eth.ForkchoiceUpdateErr(fcRes.PayloadStatus)
 	}
 	id := fcRes.PayloadID
 	if id == nil {
-		return nil, errors.New("nil id in forkchoice result when expecting a valid ID"), nil
+		return nil, BlockInsertTemporaryErr, errors.New("nil id in forkchoice result when expecting a valid ID")
 	}
 	payload, err := eng.GetPayload(ctx, *id)
 	if err != nil {
-		return nil, fmt.Errorf("failed to get execution payload: %w", err), nil
+		// even if it is an input-error (unknown payload ID), it is temporary, since we will re-attempt the full payload building, not just the retrieval of the payload.
+		return nil, BlockInsertTemporaryErr, fmt.Errorf("failed to get execution payload: %w", err)
 	}
 	if err := sanityCheckPayload(payload); err != nil {
-		return nil, nil, err
+		return nil, BlockInsertPayloadErr, err
 	}
 
 	status, err := eng.NewPayload(ctx, payload)
 	if err != nil {
-		return nil, fmt.Errorf("failed to insert execution payload: %w", err), nil
+		return nil, BlockInsertTemporaryErr, fmt.Errorf("failed to insert execution payload: %w", err)
 	}
 	if status.Status == eth.ExecutionInvalid || status.Status == eth.ExecutionInvalidBlockHash {
-		return nil, nil, eth.NewPayloadErr(payload, status)
+		return nil, BlockInsertPayloadErr, eth.NewPayloadErr(payload, status)
 	}
 	if status.Status != eth.ExecutionValid {
-		return nil, eth.NewPayloadErr(payload, status), nil
+		return nil, BlockInsertTemporaryErr, eth.NewPayloadErr(payload, status)
 	}
 
 	fc.HeadBlockHash = payload.BlockHash
@@ -110,14 +136,25 @@ func InsertHeadBlock(ctx context.Context, log log.Logger, eng Engine, fc eth.For
 	}
 	fcRes, err = eng.ForkchoiceUpdate(ctx, &fc, nil)
 	if err != nil {
-		return nil, fmt.Errorf("failed to make the new L2 block canonical via forkchoice: %w", err), nil
+		var inputErr eth.InputError
+		if errors.As(err, &inputErr) {
+			switch inputErr.Code {
+			case eth.InvalidForkchoiceState:
+				// if we succeed to update the forkchoice pre-payload, but fail post-payload, then it is a payload error
+				return nil, BlockInsertPayloadErr, fmt.Errorf("post-block-creation forkchoice update was inconsistent with engine, need reset to resolve: %w", inputErr.Unwrap())
+			default:
+				return nil, BlockInsertPrestateErr, fmt.Errorf("unexpected error code in forkchoice-updated response: %w", err)
+			}
+		} else {
+			return nil, BlockInsertTemporaryErr, fmt.Errorf("failed to make the new L2 block canonical via forkchoice: %w", err)
+		}
 	}
 	if fcRes.PayloadStatus.Status != eth.ExecutionValid {
-		return nil, eth.ForkchoiceUpdateErr(fcRes.PayloadStatus), nil
+		return nil, BlockInsertPayloadErr, eth.ForkchoiceUpdateErr(fcRes.PayloadStatus)
 	}
 	log.Info("inserted block", "hash", payload.BlockHash, "number", uint64(payload.BlockNumber),
 		"state_root", payload.StateRoot, "timestamp", uint64(payload.Timestamp), "parent", payload.ParentHash,
 		"prev_randao", payload.PrevRandao, "fee_recipient", payload.FeeRecipient,
 		"txs", len(payload.Transactions), "update_safe", updateSafe)
-	return payload, nil, nil
+	return payload, BlockInsertOK, nil
 }

op-node/rollup/driver/step.go

@@ -45,12 +45,9 @@ func (d *outputImpl) createNewBlock(ctx context.Context, l2Head eth.L2BlockRef,
 	}
 
 	// Actually execute the block and add it to the head of the chain.
-	payload, rpcErr, payloadErr := derive.InsertHeadBlock(ctx, d.log, d.l2, fc, attrs, false)
-	if rpcErr != nil {
-		return l2Head, nil, fmt.Errorf("failed to extend L2 chain due to RPC error: %v", rpcErr)
-	}
-	if payloadErr != nil {
-		return l2Head, nil, fmt.Errorf("failed to extend L2 chain, cannot produce valid payload: %v", payloadErr)
+	payload, errType, err := derive.InsertHeadBlock(ctx, d.log, d.l2, fc, attrs, false)
+	if err != nil {
+		return l2Head, nil, fmt.Errorf("failed to extend L2 chain, error (%d): %w", errType, err)
 	}
 
 	// Generate an L2 block ref from the payload.

op-node/sources/engine_client.go

@@ -43,8 +43,10 @@ func NewEngineClient(client client.RPC, log log.Logger, metrics caching.Metrics,
 // ForkchoiceUpdate updates the forkchoice on the execution client. If attributes is not nil, the engine client will also begin building a block
 // based on attributes after the new head block and return the payload ID.
 //
-// The RPC may return an error in ForkchoiceUpdatedResult.PayloadStatusV1.ValidationError or other non-success PayloadStatusV1,
-// and this type of error is kept separate from the returned `error` used for RPC errors, like timeouts.
+// The RPC may return three types of errors:
+// 1. Processing error: ForkchoiceUpdatedResult.PayloadStatusV1.ValidationError or other non-success PayloadStatusV1,
+// 2. `error` as eth.InputError: the forkchoice state or attributes are not valid.
+// 3. Other types of `error`: temporary RPC errors, like timeouts.
 func (s *EngineClient) ForkchoiceUpdate(ctx context.Context, fc *eth.ForkchoiceState, attributes *eth.PayloadAttributes) (*eth.ForkchoiceUpdatedResult, error) {
 	e := s.log.New("state", fc, "attr", attributes)
 	e.Trace("Sharing forkchoice-updated signal")
@@ -59,12 +61,18 @@ func (s *EngineClient) ForkchoiceUpdate(ctx context.Context, fc *eth.ForkchoiceS
 		}
 		return &result, nil
 	} else {
-		e = e.New("err", err)
+		e.Warn("Failed to share forkchoice-updated signal", "err", err)
 		if rpcErr, ok := err.(rpc.Error); ok {
 			code := eth.ErrorCode(rpcErr.ErrorCode())
-			e.Warn("Unexpected error code in forkchoice-updated response", "code", code)
-		} else {
-			e.Error("Failed to share forkchoice-updated signal")
+			switch code {
+			case eth.InvalidForkchoiceState, eth.InvalidPayloadAttributes:
+				return nil, eth.InputError{
+					Inner: err,
+					Code:  code,
+				}
+			default:
+				return nil, fmt.Errorf("unrecognized rpc error: %w", err)
+			}
 		}
 		return nil, err
 	}
@@ -89,23 +97,28 @@ func (s *EngineClient) NewPayload(ctx context.Context, payload *eth.ExecutionPay
 	return &result, nil
 }
 
-// GetPayload gets the execution payload associated with the PayloadId
+// GetPayload gets the execution payload associated with the PayloadId.
+// There may be two types of error:
+// 1. `error` as eth.InputError: the payload ID may be unknown
+// 2. Other types of `error`: temporary RPC errors, like timeouts.
 func (s *EngineClient) GetPayload(ctx context.Context, payloadId eth.PayloadID) (*eth.ExecutionPayload, error) {
 	e := s.log.New("payload_id", payloadId)
 	e.Trace("getting payload")
 	var result eth.ExecutionPayload
 	err := s.client.CallContext(ctx, &result, "engine_getPayloadV1", payloadId)
 	if err != nil {
-		e = e.New("payload_id", payloadId, "err", err)
+		e.Warn("Failed to get payload", "payload_id", payloadId, "err", err)
 		if rpcErr, ok := err.(rpc.Error); ok {
 			code := eth.ErrorCode(rpcErr.ErrorCode())
-			if code != eth.UnavailablePayload {
-				e.Warn("unexpected error code in get-payload response", "code", code)
-			} else {
-				e.Warn("unavailable payload in get-payload request", "code", code)
+			switch code {
+			case eth.UnknownPayload:
+				return nil, eth.InputError{
+					Inner: err,
+					Code:  code,
+				}
+			default:
+				return nil, fmt.Errorf("unrecognized rpc error: %w", err)
 			}
-		} else {
-			e.Error("failed to get payload")
 		}
 		return nil, err
 	}