op-challenger: PoC for super node trace provider

op-challenger/game/fault/trace/super/provider_supernode.go

@@ -0,0 +1,169 @@
+package super
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/ethereum-optimism/optimism/op-challenger/game/client"
+	"github.com/ethereum-optimism/optimism/op-challenger/game/fault/types"
+	interopTypes "github.com/ethereum-optimism/optimism/op-program/client/interop/types"
+	"github.com/ethereum-optimism/optimism/op-service/eth"
+	"github.com/ethereum-optimism/optimism/op-supernode/supernode/activity/superroot"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/log"
+)
+
+type SuperNodeRootProvider interface {
+	// TODO: If AtTimestampResponse is being reused it should be put in op-service
+	SuperRootAtTimestamp(ctx context.Context, timestamp uint64) (superroot.AtTimestampResponse, error)
+}
+
+type SuperNodeTraceProvider struct {
+	PreimagePrestateProvider
+	logger             log.Logger
+	rootProvider       SuperNodeRootProvider
+	prestateTimestamp  uint64
+	poststateTimestamp uint64
+	l1Head             eth.BlockID
+	gameDepth          types.Depth
+}
+
+func NewSuperNodeTraceProvider(logger log.Logger, prestateProvider PreimagePrestateProvider, rootProvider SuperNodeRootProvider, l1Head eth.BlockID, gameDepth types.Depth, prestateTimestamp, poststateTimestamp uint64) *SuperNodeTraceProvider {
+	return &SuperNodeTraceProvider{
+		logger:                   logger,
+		PreimagePrestateProvider: prestateProvider,
+		rootProvider:             rootProvider,
+		prestateTimestamp:        prestateTimestamp,
+		poststateTimestamp:       poststateTimestamp,
+		l1Head:                   l1Head,
+		gameDepth:                gameDepth,
+	}
+}
+
+func (s *SuperNodeTraceProvider) Get(ctx context.Context, pos types.Position) (common.Hash, error) {
+	preimage, err := s.GetPreimageBytes(ctx, pos)
+	if err != nil {
+		return common.Hash{}, err
+	}
+	return crypto.Keccak256Hash(preimage), nil
+}
+
+func (s *SuperNodeTraceProvider) getPreimageBytesAtTimestampBoundary(ctx context.Context, timestamp uint64) ([]byte, error) {
+	root, err := s.rootProvider.SuperRootAtTimestamp(ctx, timestamp)
+	if err != nil {
+		return nil, fmt.Errorf("failed to retrieve super root at timestamp %v: %w", timestamp, err)
+	}
+	if root.CurrentL1.Number < s.l1Head.Number {
+		// Node has not processed the game's L1 head so it is not safe to play until it syncs further.
+		return nil, client.ErrNotInSync
+	}
+	if root.Data == nil {
+		// No block at this timestamp so it must be invalid
+		return InvalidTransition, nil
+	}
+	if root.Data.VerifiedRequiredL1.Number > s.l1Head.Number {
+		return InvalidTransition, nil
+	}
+	return root.Data.Super.Marshal(), nil
+}
+
+func (s *SuperNodeTraceProvider) GetPreimageBytes(ctx context.Context, pos types.Position) ([]byte, error) {
+	// Find the timestamp and step at position
+	timestamp, step, err := s.ComputeStep(pos)
+	if err != nil {
+		return nil, err
+	}
+	s.logger.Trace("Getting claim", "pos", pos.ToGIndex(), "timestamp", timestamp, "step", step)
+	if step == 0 {
+		return s.getPreimageBytesAtTimestampBoundary(ctx, timestamp)
+	}
+	// Fetch the super root at the next timestamp since we are part way through the transition to it
+	prevRoot, err := s.rootProvider.SuperRootAtTimestamp(ctx, timestamp)
+	if err != nil {
+		return nil, fmt.Errorf("failed to retrieve previous super root at timestamp %v: %w", timestamp, err)
+	}
+	if prevRoot.CurrentL1.Number < s.l1Head.Number {
+		return nil, client.ErrNotInSync
+	}
+	if prevRoot.Data == nil {
+		// No block at this timestamp so it must be invalid
+		return InvalidTransition, nil
+	}
+	if prevRoot.Data.VerifiedRequiredL1.Number > s.l1Head.Number {
+		// The previous root was not safe at the game L1 head so we must have already transitioned to the invalid hash
+		// prior to this step and it then repeats forever.
+		return InvalidTransition, nil
+	}
+	nextTimestamp := timestamp + 1
+	nextRoot, err := s.rootProvider.SuperRootAtTimestamp(ctx, nextTimestamp)
+	if err != nil {
+		return nil, fmt.Errorf("failed to retrieve next super root at timestamp %v: %w", nextTimestamp, err)
+	}
+	if nextRoot.CurrentL1.Number < s.l1Head.Number {
+		return nil, client.ErrNotInSync
+	}
+	if nextRoot.Data == nil {
+		// No block at this timestamp so it must be invalid
+		return InvalidTransition, nil
+	}
+
+	prevSuper := prevRoot.Data.Super
+	expectedState := interopTypes.TransitionState{
+		SuperRoot:       prevSuper.Marshal(),
+		PendingProgress: make([]interopTypes.OptimisticBlock, 0, step),
+		Step:            step,
+	}
+	nextSuperV1, ok := nextRoot.Data.Super.(*eth.SuperV1)
+	if !ok {
+		return nil, fmt.Errorf("unsupported super root type %T", nextRoot.Data.Super)
+	}
+	for i := uint64(0); i < min(step, uint64(len(nextSuperV1.Chains))); i++ {
+		chainInfo := nextSuperV1.Chains[i]
+		// Check if the chain's optimistic root was safe at the game's L1 head
+		optimistic, ok := nextRoot.Data.UnverifiedAtTimestamp[chainInfo.ChainID]
+		if !ok {
+			return nil, fmt.Errorf("no safe head known for chain %v at %v: %w", chainInfo.ChainID, nextTimestamp, err)
+		}
+		if optimistic.RequiredL1.Number > s.l1Head.Number {
+			// Not enough data on L1 to derive the optimistic block, move to invalid transition.
+			return InvalidTransition, nil
+		}
+
+		expectedState.PendingProgress = append(expectedState.PendingProgress, interopTypes.OptimisticBlock{
+			BlockHash:  optimistic.Output.BlockRef.Hash,
+			OutputRoot: optimistic.Output.OutputRoot,
+		})
+	}
+	return expectedState.Marshal(), nil
+}
+
+func (s *SuperNodeTraceProvider) ComputeStep(pos types.Position) (timestamp uint64, step uint64, err error) {
+	bigIdx := pos.TraceIndex(s.gameDepth)
+	if !bigIdx.IsUint64() {
+		err = fmt.Errorf("%w: %v", ErrIndexTooBig, bigIdx)
+		return
+	}
+
+	traceIdx := bigIdx.Uint64() + 1
+	timestampIncrements := traceIdx / StepsPerTimestamp
+	timestamp = s.prestateTimestamp + timestampIncrements
+	if timestamp >= s.poststateTimestamp { // Apply trace extension once the claimed timestamp is reached
+		timestamp = s.poststateTimestamp
+		step = 0
+	} else {
+		step = traceIdx % StepsPerTimestamp
+	}
+	return
+}
+
+func (s *SuperNodeTraceProvider) GetStepData(_ context.Context, _ types.Position) (prestate []byte, proofData []byte, preimageData *types.PreimageOracleData, err error) {
+	return nil, nil, nil, ErrGetStepData
+}
+
+func (s *SuperNodeTraceProvider) GetL2BlockNumberChallenge(_ context.Context) (*types.InvalidL2BlockNumberChallenge, error) {
+	// Never need to challenge L2 block number for super root games.
+	return nil, types.ErrL2BlockNumberValid
+}
+
+var _ types.TraceProvider = (*SuperNodeTraceProvider)(nil)