package statesync import ( "context" "fmt" "strings" "time" dbm "github.com/tendermint/tm-db" "github.com/tendermint/tendermint/libs/log" tmsync "github.com/tendermint/tendermint/libs/sync" "github.com/tendermint/tendermint/light" lightprovider "github.com/tendermint/tendermint/light/provider" lighthttp "github.com/tendermint/tendermint/light/provider/http" lightrpc "github.com/tendermint/tendermint/light/rpc" lightdb "github.com/tendermint/tendermint/light/store/db" rpchttp "github.com/tendermint/tendermint/rpc/client/http" sm "github.com/tendermint/tendermint/state" "github.com/tendermint/tendermint/types" ) //go:generate mockery --case underscore --name StateProvider // StateProvider is a provider of trusted state data for bootstrapping a node. This refers // to the state.State object, not the state machine. type StateProvider interface { // AppHash returns the app hash after the given height has been committed. AppHash(ctx context.Context, height uint64) ([]byte, error) // Commit returns the commit at the given height. Commit(ctx context.Context, height uint64) (*types.Commit, error) // State returns a state object at the given height. State(ctx context.Context, height uint64) (sm.State, error) } // lightClientStateProvider is a state provider using the light client. type lightClientStateProvider struct { tmsync.Mutex // light.Client is not concurrency-safe lc *light.Client version sm.Version initialHeight int64 providers map[lightprovider.Provider]string } // NewLightClientStateProvider creates a new StateProvider using a light client and RPC clients. func NewLightClientStateProvider( ctx context.Context, chainID string, version sm.Version, initialHeight int64, servers []string, trustOptions light.TrustOptions, logger log.Logger, ) (StateProvider, error) { if len(servers) < 2 { return nil, fmt.Errorf("at least 2 RPC servers are required, got %v", len(servers)) } providers := make([]lightprovider.Provider, 0, len(servers)) providerRemotes := make(map[lightprovider.Provider]string) for _, server := range servers { client, err := rpcClient(server) if err != nil { return nil, fmt.Errorf("failed to set up RPC client: %w", err) } provider := lighthttp.NewWithClient(chainID, client) providers = append(providers, provider) // We store the RPC addresses keyed by provider, so we can find the address of the primary // provider used by the light client and use it to fetch consensus parameters. providerRemotes[provider] = server } lc, err := light.NewClient(ctx, chainID, trustOptions, providers[0], providers[1:], lightdb.New(dbm.NewMemDB()), light.Logger(logger)) if err != nil { return nil, err } return &lightClientStateProvider{ lc: lc, version: version, initialHeight: initialHeight, providers: providerRemotes, }, nil } // AppHash implements StateProvider. func (s *lightClientStateProvider) AppHash(ctx context.Context, height uint64) ([]byte, error) { s.Lock() defer s.Unlock() // We have to fetch the next height, which contains the app hash for the previous height. header, err := s.lc.VerifyLightBlockAtHeight(ctx, int64(height+1), time.Now()) if err != nil { return nil, err } // We also try to fetch the blocks at height H and H+2, since we need these // when building the state while restoring the snapshot. This avoids the race // condition where we try to restore a snapshot before H+2 exists. // // FIXME This is a hack, since we can't add new methods to the interface without // breaking it. We should instead have a Has(ctx, height) method which checks // that the state provider has access to the necessary data for the height. // We piggyback on AppHash() since it's called when adding snapshots to the pool. _, err = s.lc.VerifyLightBlockAtHeight(ctx, int64(height+2), time.Now()) if err != nil { return nil, err } _, err = s.lc.VerifyLightBlockAtHeight(ctx, int64(height), time.Now()) if err != nil { return nil, err } return header.AppHash, nil } // Commit implements StateProvider. func (s *lightClientStateProvider) Commit(ctx context.Context, height uint64) (*types.Commit, error) { s.Lock() defer s.Unlock() header, err := s.lc.VerifyLightBlockAtHeight(ctx, int64(height), time.Now()) if err != nil { return nil, err } return header.Commit, nil } // State implements StateProvider. func (s *lightClientStateProvider) State(ctx context.Context, height uint64) (sm.State, error) { s.Lock() defer s.Unlock() state := sm.State{ ChainID: s.lc.ChainID(), Version: s.version, InitialHeight: s.initialHeight, } if state.InitialHeight == 0 { state.InitialHeight = 1 } // The snapshot height maps onto the state heights as follows: // // height: last block, i.e. the snapshotted height // height+1: current block, i.e. the first block we'll process after the snapshot // height+2: next block, i.e. the second block after the snapshot // // We need to fetch the NextValidators from height+2 because if the application changed // the validator set at the snapshot height then this only takes effect at height+2. lastLightBlock, err := s.lc.VerifyLightBlockAtHeight(ctx, int64(height), time.Now()) if err != nil { return sm.State{}, err } currentLightBlock, err := s.lc.VerifyLightBlockAtHeight(ctx, int64(height+1), time.Now()) if err != nil { return sm.State{}, err } nextLightBlock, err := s.lc.VerifyLightBlockAtHeight(ctx, int64(height+2), time.Now()) if err != nil { return sm.State{}, err } state.LastBlockHeight = lastLightBlock.Height state.LastBlockTime = lastLightBlock.Time state.LastBlockID = lastLightBlock.Commit.BlockID state.AppHash = currentLightBlock.AppHash state.LastResultsHash = currentLightBlock.LastResultsHash state.LastValidators = lastLightBlock.ValidatorSet state.Validators = currentLightBlock.ValidatorSet state.NextValidators = nextLightBlock.ValidatorSet state.LastHeightValidatorsChanged = nextLightBlock.Height // We'll also need to fetch consensus params via RPC, using light client verification. primaryURL, ok := s.providers[s.lc.Primary()] if !ok || primaryURL == "" { return sm.State{}, fmt.Errorf("could not find address for primary light client provider") } primaryRPC, err := rpcClient(primaryURL) if err != nil { return sm.State{}, fmt.Errorf("unable to create RPC client: %w", err) } rpcclient := lightrpc.NewClient(primaryRPC, s.lc) result, err := rpcclient.ConsensusParams(ctx, ¤tLightBlock.Height) if err != nil { return sm.State{}, fmt.Errorf("unable to fetch consensus parameters for height %v: %w", nextLightBlock.Height, err) } state.ConsensusParams = result.ConsensusParams state.LastHeightConsensusParamsChanged = currentLightBlock.Height return state, nil } // rpcClient sets up a new RPC client func rpcClient(server string) (*rpchttp.HTTP, error) { if !strings.Contains(server, "://") { server = "http://" + server } c, err := rpchttp.New(server) if err != nil { return nil, err } return c, nil }