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op-challenger: route large-preimage uploads only for keccak keys #19168

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Merged
ajsutton merged 1 commit into from
Feb 12, 2026
Merged

op-challenger: route large-preimage uploads only for keccak keys #19168

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5 changes: 4 additions & 1 deletion op-challenger/game/fault/preimages/split.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ import (
"context"

"github.com/ethereum-optimism/optimism/op-challenger/game/fault/types"
preimage "github.com/ethereum-optimism/optimism/op-preimage"
)

var _ PreimageUploader = (*SplitPreimageUploader)(nil)
Expand All @@ -25,7 +26,9 @@ func (s *SplitPreimageUploader) UploadPreimage(ctx context.Context, parent uint6
return ErrNilPreimageData
}
// Always route local preimage uploads to the direct uploader.
if data.IsLocal || uint64(len(data.GetPreimageWithoutSize())) < s.largePreimageSizeThreshold {
// Large-preimage proposals are keccak-only on-chain, so non-keccak preimages must go through the direct path.
isKeccak := len(data.OracleKey) > 0 && preimage.KeyType(data.OracleKey[0]) == preimage.Keccak256KeyType
if data.IsLocal || !isKeccak || uint64(len(data.GetPreimageWithoutSize())) < s.largePreimageSizeThreshold {
return s.directUploader.UploadPreimage(ctx, parent, data)
} else {
return s.largeUploader.UploadPreimage(ctx, parent, data)
Expand Down
21 changes: 21 additions & 0 deletions op-challenger/game/fault/preimages/split_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,9 +2,12 @@ package preimages

import (
"context"
"crypto/sha256"
"encoding/binary"
"testing"

"github.com/ethereum-optimism/optimism/op-challenger/game/fault/types"
preimage "github.com/ethereum-optimism/optimism/op-preimage"
"github.com/stretchr/testify/require"
)

Expand Down Expand Up @@ -43,6 +46,14 @@ func TestSplitPreimageUploader_UploadPreimage(t *testing.T) {
require.Equal(t, 0, direct.updates)
})

t.Run("NonKeccakAlwaysUsesDirect", func(t *testing.T) {
oracle, direct, large := newTestSplitPreimageUploader(t, mockLargePreimageSizeThreshold)
err := oracle.UploadPreimage(context.Background(), 0, makeSha256PreimageData(make([]byte, mockLargePreimageSizeThreshold), 0))
require.NoError(t, err)
require.Equal(t, 1, direct.updates)
require.Equal(t, 0, large.updates)
})

t.Run("NilPreimageOracleData", func(t *testing.T) {
oracle, _, _ := newTestSplitPreimageUploader(t, mockLargePreimageSizeThreshold)
err := oracle.UploadPreimage(context.Background(), 0, nil)
Expand All @@ -68,3 +79,13 @@ func newTestSplitPreimageUploader(t *testing.T, threshold uint64) (*SplitPreimag
large := &mockPreimageUploader{}
return NewSplitPreimageUploader(direct, large, threshold), direct, large
}

func makeSha256PreimageData(pre []byte, offset uint32) *types.PreimageOracleData {
sum := sha256.Sum256(pre)
key := preimage.Sha256Key(sum).PreimageKey()
// Add the length prefix to match how Cannon formats oracle data.
dataWithLength := make([]byte, 0, 8+len(pre))
dataWithLength = binary.BigEndian.AppendUint64(dataWithLength, uint64(len(pre)))
dataWithLength = append(dataWithLength, pre...)
return types.NewPreimageOracleData(key[:], dataWithLength, offset)
}