cli: add --hard flag to rollback command to remove block as well

cmd/cometbft/commands/rollback.go

@@ -14,32 +14,44 @@ import (
 	"github.com/tendermint/tendermint/store"
 )
 
+var removeBlock = false
+
+func init() {
+	RollbackStateCmd.Flags().BoolVar(&removeBlock, "hard", false, "remove last block as well as state")
+}
+
 var RollbackStateCmd = &cobra.Command{
 	Use:   "rollback",
 	Short: "rollback CometBFT state by one height",
 	Long: `
 A state rollback is performed to recover from an incorrect application state transition,
 when CometBFT has persisted an incorrect app hash and is thus unable to make
 progress. Rollback overwrites a state at height n with the state at height n - 1.
-The application should also roll back to height n - 1. No blocks are removed, so upon
-restarting CometBFT the transactions in block n will be re-executed against the
-application.
+The application should also roll back to height n - 1. If the --hard flag is not used,
+no blocks will be removed so upon restarting Tendermint the transactions in block n will be
+re-executed against the application. Using --hard will also remove block n. This can
+be done multiple times.
 `,
 	RunE: func(cmd *cobra.Command, args []string) error {
-		height, hash, err := RollbackState(config)
+		height, hash, err := RollbackState(config, removeBlock)
 		if err != nil {
 			return fmt.Errorf("failed to rollback state: %w", err)
 		}
 
-		fmt.Printf("Rolled back state to height %d and hash %v", height, hash)
+		if removeBlock {
+			fmt.Printf("Rolled back both state and block to height %d and hash %X\n", height, hash)
+		} else {
+			fmt.Printf("Rolled back state to height %d and hash %X\n", height, hash)
+		}
+
 		return nil
 	},
 }
 
 // RollbackState takes the state at the current height n and overwrites it with the state
 // at height n - 1. Note state here refers to CometBFT state not application state.
 // Returns the latest state height and app hash alongside an error if there was one.
-func RollbackState(config *cfg.Config) (int64, []byte, error) {
+func RollbackState(config *cfg.Config, removeBlock bool) (int64, []byte, error) {
 	// use the parsed config to load the block and state store
 	blockStore, stateStore, err := loadStateAndBlockStore(config)
 	if err != nil {
@@ -51,7 +63,7 @@ func RollbackState(config *cfg.Config) (int64, []byte, error) {
 	}()
 
 	// rollback the last state
-	return state.Rollback(blockStore, stateStore)
+	return state.Rollback(blockStore, stateStore, removeBlock)
 }
 
 func loadStateAndBlockStore(config *cfg.Config) (*store.BlockStore, state.Store, error) {

consensus/replay_test.go

@@ -1232,6 +1232,8 @@ func (bs *mockBlockStore) PruneBlocks(height int64) (uint64, error) {
 	return pruned, nil
 }
 
+func (bs *mockBlockStore) DeleteLatestBlock() error { return nil }
+
 //---------------------------------------
 // Test handshake/init chain
 

rpc/core/blocks_test.go

@@ -134,3 +134,4 @@ func (mockBlockStore) LoadSeenCommit(height int64) *types.Commit         { retur
 func (mockBlockStore) PruneBlocks(height int64) (uint64, error)          { return 0, nil }
 func (mockBlockStore) SaveBlock(block *types.Block, blockParts *types.PartSet, seenCommit *types.Commit) {
 }
+func (mockBlockStore) DeleteLatestBlock() error { return nil }

state/rollback.go

@@ -12,7 +12,7 @@ import (
 // Rollback overwrites the current CometBFT state (height n) with the most
 // recent previous state (height n - 1).
 // Note that this function does not affect application state.
-func Rollback(bs BlockStore, ss Store) (int64, []byte, error) {
+func Rollback(bs BlockStore, ss Store, removeBlock bool) (int64, []byte, error) {
 	invalidState, err := ss.Load()
 	if err != nil {
 		return -1, nil, err
@@ -24,9 +24,14 @@ func Rollback(bs BlockStore, ss Store) (int64, []byte, error) {
 	height := bs.Height()
 
 	// NOTE: persistence of state and blocks don't happen atomically. Therefore it is possible that
-	// when the user stopped the node the state wasn't updated but the blockstore was. In this situation
-	// we don't need to rollback any state and can just return early
+	// when the user stopped the node the state wasn't updated but the blockstore was. Discard the
+	// pending block before continuing.
 	if height == invalidState.LastBlockHeight+1 {
+		if removeBlock {
+			if err := bs.DeleteLatestBlock(); err != nil {
+				return -1, nil, fmt.Errorf("failed to remove final block from blockstore: %w", err)
+			}
+		}
 		return invalidState.LastBlockHeight, invalidState.AppHash, nil
 	}
 
@@ -108,5 +113,13 @@ func Rollback(bs BlockStore, ss Store) (int64, []byte, error) {
 		return -1, nil, fmt.Errorf("failed to save rolled back state: %w", err)
 	}
 
+	// If removeBlock is true then also remove the block associated with the previous state.
+	// This will mean both the last state and last block height is equal to n - 1
+	if removeBlock {
+		if err := bs.DeleteLatestBlock(); err != nil {
+			return -1, nil, fmt.Errorf("failed to remove final block from blockstore: %w", err)
+		}
+	}
+
 	return rolledBackState.LastBlockHeight, rolledBackState.AppHash, nil
 }

state/rollback_test.go

@@ -3,6 +3,7 @@ package state_test
 import (
 	"crypto/rand"
 	"testing"
+	"time"
 
 	dbm "github.com/cometbft/cometbft-db"
 	"github.com/stretchr/testify/require"
@@ -13,6 +14,7 @@ import (
 	cmtversion "github.com/tendermint/tendermint/proto/tendermint/version"
 	"github.com/tendermint/tendermint/state"
 	"github.com/tendermint/tendermint/state/mocks"
+	"github.com/tendermint/tendermint/store"
 	"github.com/tendermint/tendermint/types"
 	"github.com/tendermint/tendermint/version"
 )
@@ -50,6 +52,7 @@ func TestRollback(t *testing.T) {
 		BlockID: initialState.LastBlockID,
 		Header: types.Header{
 			Height:          initialState.LastBlockHeight,
+			Time:            initialState.LastBlockTime,
 			AppHash:         crypto.CRandBytes(tmhash.Size),
 			LastBlockID:     makeBlockIDRandom(),
 			LastResultsHash: initialState.LastResultsHash,
@@ -61,6 +64,7 @@ func TestRollback(t *testing.T) {
 			Height:          nextState.LastBlockHeight,
 			AppHash:         initialState.AppHash,
 			LastBlockID:     block.BlockID,
+			Time:            nextState.LastBlockTime,
 			LastResultsHash: nextState.LastResultsHash,
 		},
 	}
@@ -69,7 +73,7 @@ func TestRollback(t *testing.T) {
 	blockStore.On("Height").Return(nextHeight)
 
 	// rollback the state
-	rollbackHeight, rollbackHash, err := state.Rollback(blockStore, stateStore)
+	rollbackHeight, rollbackHash, err := state.Rollback(blockStore, stateStore, false)
 	require.NoError(t, err)
 	require.EqualValues(t, height, rollbackHeight)
 	require.EqualValues(t, initialState.AppHash, rollbackHash)
@@ -81,14 +85,126 @@ func TestRollback(t *testing.T) {
 	require.EqualValues(t, initialState, loadedState)
 }
 
+func TestRollbackHard(t *testing.T) {
+	const height int64 = 100
+	blockStore := store.NewBlockStore(dbm.NewMemDB())
+	stateStore := state.NewStore(dbm.NewMemDB(), state.StoreOptions{DiscardABCIResponses: false})
+
+	valSet, _ := types.RandValidatorSet(5, 10)
+
+	params := types.DefaultConsensusParams()
+	params.Version.AppVersion = 10
+	now := time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC)
+
+	block := &types.Block{
+		Header: types.Header{
+			Version:            cmtversion.Consensus{Block: version.BlockProtocol, App: 1},
+			ChainID:            "test-chain",
+			Time:               now,
+			Height:             height,
+			AppHash:            crypto.CRandBytes(tmhash.Size),
+			LastBlockID:        makeBlockIDRandom(),
+			LastCommitHash:     crypto.CRandBytes(tmhash.Size),
+			DataHash:           crypto.CRandBytes(tmhash.Size),
+			ValidatorsHash:     valSet.Hash(),
+			NextValidatorsHash: valSet.CopyIncrementProposerPriority(1).Hash(),
+			LastResultsHash:    crypto.CRandBytes(tmhash.Size),
+			EvidenceHash:       crypto.CRandBytes(tmhash.Size),
+			ProposerAddress:    crypto.CRandBytes(crypto.AddressSize),
+		},
+		LastCommit: &types.Commit{Height: height - 1},
+	}
+
+	partSet := block.MakePartSet(types.BlockPartSizeBytes)
+	blockStore.SaveBlock(block, partSet, &types.Commit{Height: block.Height})
+
+	currState := state.State{
+		Version: cmtstate.Version{
+			Consensus: block.Header.Version,
+			Software:  version.TMCoreSemVer,
+		},
+		LastBlockHeight:                  block.Height,
+		LastBlockTime:                    block.Time,
+		AppHash:                          crypto.CRandBytes(tmhash.Size),
+		LastValidators:                   valSet,
+		Validators:                       valSet.CopyIncrementProposerPriority(1),
+		NextValidators:                   valSet.CopyIncrementProposerPriority(2),
+		ConsensusParams:                  *params,
+		LastHeightConsensusParamsChanged: height + 1,
+		LastHeightValidatorsChanged:      height + 1,
+		LastResultsHash:                  crypto.CRandBytes(tmhash.Size),
+	}
+	require.NoError(t, stateStore.Bootstrap(currState))
+
+	nextBlock := &types.Block{
+		Header: types.Header{
+			Version:            cmtversion.Consensus{Block: version.BlockProtocol, App: 1},
+			ChainID:            block.ChainID,
+			Time:               block.Time,
+			Height:             currState.LastBlockHeight + 1,
+			AppHash:            currState.AppHash,
+			LastBlockID:        types.BlockID{Hash: block.Hash(), PartSetHeader: partSet.Header()},
+			LastCommitHash:     crypto.CRandBytes(tmhash.Size),
+			DataHash:           crypto.CRandBytes(tmhash.Size),
+			ValidatorsHash:     valSet.CopyIncrementProposerPriority(1).Hash(),
+			NextValidatorsHash: valSet.CopyIncrementProposerPriority(2).Hash(),
+			LastResultsHash:    currState.LastResultsHash,
+			EvidenceHash:       crypto.CRandBytes(tmhash.Size),
+			ProposerAddress:    crypto.CRandBytes(crypto.AddressSize),
+		},
+		LastCommit: &types.Commit{Height: currState.LastBlockHeight},
+	}
+
+	nextPartSet := nextBlock.MakePartSet(types.BlockPartSizeBytes)
+	blockStore.SaveBlock(nextBlock, nextPartSet, &types.Commit{Height: nextBlock.Height})
+
+	rollbackHeight, rollbackHash, err := state.Rollback(blockStore, stateStore, true)
+	require.NoError(t, err)
+	require.Equal(t, rollbackHeight, currState.LastBlockHeight)
+	require.Equal(t, rollbackHash, currState.AppHash)
+
+	// state should not have been changed
+	loadedState, err := stateStore.Load()
+	require.NoError(t, err)
+	require.Equal(t, currState, loadedState)
+
+	// resave the same block
+	blockStore.SaveBlock(nextBlock, nextPartSet, &types.Commit{Height: nextBlock.Height})
+
+	params.Version.AppVersion = 11
+
+	nextState := state.State{
+		Version: cmtstate.Version{
+			Consensus: block.Header.Version,
+			Software:  version.TMCoreSemVer,
+		},
+		LastBlockHeight:                  nextBlock.Height,
+		LastBlockTime:                    nextBlock.Time,
+		AppHash:                          crypto.CRandBytes(tmhash.Size),
+		LastValidators:                   valSet.CopyIncrementProposerPriority(1),
+		Validators:                       valSet.CopyIncrementProposerPriority(2),
+		NextValidators:                   valSet.CopyIncrementProposerPriority(3),
+		ConsensusParams:                  *params,
+		LastHeightConsensusParamsChanged: nextBlock.Height + 1,
+		LastHeightValidatorsChanged:      nextBlock.Height + 1,
+		LastResultsHash:                  crypto.CRandBytes(tmhash.Size),
+	}
+	require.NoError(t, stateStore.Save(nextState))
+
+	rollbackHeight, rollbackHash, err = state.Rollback(blockStore, stateStore, true)
+	require.NoError(t, err)
+	require.Equal(t, rollbackHeight, currState.LastBlockHeight)
+	require.Equal(t, rollbackHash, currState.AppHash)
+}
+
 func TestRollbackNoState(t *testing.T) {
 	stateStore := state.NewStore(dbm.NewMemDB(),
 		state.StoreOptions{
 			DiscardABCIResponses: false,
 		})
 	blockStore := &mocks.BlockStore{}
 
-	_, _, err := state.Rollback(blockStore, stateStore)
+	_, _, err := state.Rollback(blockStore, stateStore, false)
 	require.Error(t, err)
 	require.Contains(t, err.Error(), "no state found")
 }
@@ -101,7 +217,7 @@ func TestRollbackNoBlocks(t *testing.T) {
 	blockStore.On("LoadBlockMeta", height).Return(nil)
 	blockStore.On("LoadBlockMeta", height-1).Return(nil)
 
-	_, _, err := state.Rollback(blockStore, stateStore)
+	_, _, err := state.Rollback(blockStore, stateStore, false)
 	require.Error(t, err)
 	require.Contains(t, err.Error(), "block at height 99 not found")
 }
@@ -112,7 +228,7 @@ func TestRollbackDifferentStateHeight(t *testing.T) {
 	blockStore := &mocks.BlockStore{}
 	blockStore.On("Height").Return(height + 2)
 
-	_, _, err := state.Rollback(blockStore, stateStore)
+	_, _, err := state.Rollback(blockStore, stateStore, false)
 	require.Error(t, err)
 	require.Equal(t, err.Error(), "statestore height (100) is not one below or equal to blockstore height (102)")
 }

state/services.go

@@ -33,6 +33,8 @@ type BlockStore interface {
 
 	LoadBlockCommit(height int64) *types.Commit
 	LoadSeenCommit(height int64) *types.Commit
+
+	DeleteLatestBlock() error
 }
 
 //-----------------------------------------------------------------------------