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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"
tmstate "github.com/tendermint/tendermint/proto/tendermint/state"
rpchttp "github.com/tendermint/tendermint/rpc/client/http"
sm "github.com/tendermint/tendermint/state"
"github.com/tendermint/tendermint/types"
"github.com/tendermint/tendermint/version"
)
//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 tmstate.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 tmstate.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), light.MaxRetryAttempts(5))
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
}
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.Version = tmstate.Version{
Consensus: currentLightBlock.Version,
Software: version.TMCoreSemVer,
}
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, &currentLightBlock.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, "/websocket")
if err != nil {
return nil, err
}
return c, nil
}