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package cross
import (
"errors"
"fmt"
"github.com/ethereum-optimism/optimism/op-service/eth"
"github.com/ethereum-optimism/optimism/op-supervisor/supervisor/backend/depset"
"github.com/ethereum-optimism/optimism/op-supervisor/supervisor/types"
)
type UnsafeFrontierCheckDeps interface {
ParentBlock(chainID types.ChainID, parentOf eth.BlockID) (parent eth.BlockID, err error)
IsCrossUnsafe(chainID types.ChainID, block eth.BlockID) error
IsLocalUnsafe(chainID types.ChainID, block eth.BlockID) error
DependencySet() depset.DependencySet
}
// HazardUnsafeFrontierChecks verifies all the hazard blocks are either:
// - already cross-unsafe.
// - the first (if not first: local blocks to verify before proceeding)
// local-unsafe block, after the cross-unsafe block.
func HazardUnsafeFrontierChecks(d UnsafeFrontierCheckDeps, hazards map[types.ChainIndex]types.BlockSeal) error {
depSet := d.DependencySet()
for hazardChainIndex, hazardBlock := range hazards {
hazardChainID, err := depSet.ChainIDFromIndex(hazardChainIndex)
if err != nil {
if errors.Is(err, types.ErrUnknownChain) {
err = fmt.Errorf("cannot cross-unsafe verify block %s of unknown chain index %s: %w", hazardBlock, hazardChainIndex, types.ErrConflict)
}
return err
}
// Anything we depend on in this timestamp must be cross-unsafe already, or the first block after.
err = d.IsCrossUnsafe(hazardChainID, hazardBlock.ID())
if err != nil {
if errors.Is(err, types.ErrFuture) {
// Not already cross-unsafe, so we check if the block is local-unsafe
// (a sanity check if part of the canonical chain).
err = d.IsLocalUnsafe(hazardChainID, hazardBlock.ID())
if err != nil {
// can be ErrFuture (missing data) or ErrConflict (non-canonical)
return fmt.Errorf("hazard block %s (chain %d) is not local-unsafe: %w", hazardBlock, hazardChainID, err)
}
// If it doesn't have a parent block, then there is no prior block required to be cross-safe
if hazardBlock.Number > 0 {
// Check that parent of hazardBlockID is cross-safe within view
parent, err := d.ParentBlock(hazardChainID, hazardBlock.ID())
if err != nil {
return fmt.Errorf("failed to retrieve parent-block of hazard block %s (chain %s): %w", hazardBlock, hazardChainID, err)
}
if err := d.IsCrossUnsafe(hazardChainID, parent); err != nil {
return fmt.Errorf("cannot rely on hazard-block %s (chain %s), parent block %s is not cross-unsafe: %w", hazardBlock, hazardChainID, parent, err)
}
}
} else {
return fmt.Errorf("failed to determine cross-derived of hazard block %s (chain %s): %w", hazardBlock, hazardChainID, err)
}
}
}
return nil
}