go-ethereum/beacon/light/api/light_api.go

508 lines
17 KiB
Go
Executable File

// Copyright 2022 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more detaiapi.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package api
import (
"encoding/json"
"errors"
"fmt"
"io"
"net/http"
"time"
"github.com/donovanhide/eventsource"
"github.com/ethereum/go-ethereum/beacon/merkle"
"github.com/ethereum/go-ethereum/beacon/params"
"github.com/ethereum/go-ethereum/beacon/types"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
)
var (
ErrNotFound = errors.New("404 Not Found")
ErrInternal = errors.New("500 Internal Server Error")
)
type CommitteeUpdate struct {
Version string
Update types.LightClientUpdate
NextSyncCommittee types.SerializedSyncCommittee
}
// See data structure definition here:
// https://github.com/ethereum/consensus-specs/blob/dev/specs/altair/light-client/sync-protocol.md#lightclientupdate
type committeeUpdateJson struct {
Version string `json:"version"`
Data committeeUpdateData `json:"data"`
}
type committeeUpdateData struct {
Header jsonBeaconHeader `json:"attested_header"`
NextSyncCommittee types.SerializedSyncCommittee `json:"next_sync_committee"`
NextSyncCommitteeBranch merkle.Values `json:"next_sync_committee_branch"`
FinalizedHeader *jsonBeaconHeader `json:"finalized_header,omitempty"`
FinalityBranch merkle.Values `json:"finality_branch,omitempty"`
SyncAggregate types.SyncAggregate `json:"sync_aggregate"`
SignatureSlot common.Decimal `json:"signature_slot"`
}
type jsonBeaconHeader struct {
Beacon types.Header `json:"beacon"`
}
type jsonHeaderWithExecProof struct {
Beacon types.Header `json:"beacon"`
Execution json.RawMessage `json:"execution"`
ExecutionBranch merkle.Values `json:"execution_branch"`
}
// UnmarshalJSON unmarshals from JSON.
func (u *CommitteeUpdate) UnmarshalJSON(input []byte) error {
var dec committeeUpdateJson
if err := json.Unmarshal(input, &dec); err != nil {
return err
}
u.Version = dec.Version
u.NextSyncCommittee = dec.Data.NextSyncCommittee
u.Update = types.LightClientUpdate{
AttestedHeader: types.SignedHeader{
Header: dec.Data.Header.Beacon,
Signature: dec.Data.SyncAggregate,
SignatureSlot: uint64(dec.Data.SignatureSlot),
},
NextSyncCommitteeRoot: u.NextSyncCommittee.Root(),
NextSyncCommitteeBranch: dec.Data.NextSyncCommitteeBranch,
FinalityBranch: dec.Data.FinalityBranch,
}
if dec.Data.FinalizedHeader != nil {
u.Update.FinalizedHeader = &dec.Data.FinalizedHeader.Beacon
}
return nil
}
// fetcher is an interface useful for debug-harnessing the http api.
type fetcher interface {
Do(req *http.Request) (*http.Response, error)
}
// BeaconLightApi requests light client information from a beacon node REST API.
// Note: all required API endpoints are currently only implemented by Lodestar.
type BeaconLightApi struct {
url string
client fetcher
customHeaders map[string]string
}
func NewBeaconLightApi(url string, customHeaders map[string]string) *BeaconLightApi {
return &BeaconLightApi{
url: url,
client: &http.Client{
Timeout: time.Second * 10,
},
customHeaders: customHeaders,
}
}
func (api *BeaconLightApi) httpGet(path string) ([]byte, error) {
req, err := http.NewRequest("GET", api.url+path, nil)
if err != nil {
return nil, err
}
for k, v := range api.customHeaders {
req.Header.Set(k, v)
}
resp, err := api.client.Do(req)
if err != nil {
return nil, err
}
defer resp.Body.Close()
switch resp.StatusCode {
case 200:
return io.ReadAll(resp.Body)
case 404:
return nil, ErrNotFound
case 500:
return nil, ErrInternal
default:
return nil, fmt.Errorf("unexpected error from API endpoint \"%s\": status code %d", path, resp.StatusCode)
}
}
func (api *BeaconLightApi) httpGetf(format string, params ...any) ([]byte, error) {
return api.httpGet(fmt.Sprintf(format, params...))
}
// GetBestUpdatesAndCommittees fetches and validates LightClientUpdate for given
// period and full serialized committee for the next period (committee root hash
// equals update.NextSyncCommitteeRoot).
// Note that the results are validated but the update signature should be verified
// by the caller as its validity depends on the update chain.
func (api *BeaconLightApi) GetBestUpdatesAndCommittees(firstPeriod, count uint64) ([]*types.LightClientUpdate, []*types.SerializedSyncCommittee, error) {
resp, err := api.httpGetf("/eth/v1/beacon/light_client/updates?start_period=%d&count=%d", firstPeriod, count)
if err != nil {
return nil, nil, err
}
var data []CommitteeUpdate
if err := json.Unmarshal(resp, &data); err != nil {
return nil, nil, err
}
if len(data) != int(count) {
return nil, nil, errors.New("invalid number of committee updates")
}
updates := make([]*types.LightClientUpdate, int(count))
committees := make([]*types.SerializedSyncCommittee, int(count))
for i, d := range data {
if d.Update.AttestedHeader.Header.SyncPeriod() != firstPeriod+uint64(i) {
return nil, nil, errors.New("wrong committee update header period")
}
if err := d.Update.Validate(); err != nil {
return nil, nil, err
}
if d.NextSyncCommittee.Root() != d.Update.NextSyncCommitteeRoot {
return nil, nil, errors.New("wrong sync committee root")
}
updates[i], committees[i] = new(types.LightClientUpdate), new(types.SerializedSyncCommittee)
*updates[i], *committees[i] = d.Update, d.NextSyncCommittee
}
return updates, committees, nil
}
// GetOptimisticHeadUpdate fetches a signed header based on the latest available
// optimistic update. Note that the signature should be verified by the caller
// as its validity depends on the update chain.
//
// See data structure definition here:
// https://github.com/ethereum/consensus-specs/blob/dev/specs/altair/light-client/sync-protocol.md#lightclientoptimisticupdate
func (api *BeaconLightApi) GetOptimisticHeadUpdate() (types.SignedHeader, error) {
resp, err := api.httpGet("/eth/v1/beacon/light_client/optimistic_update")
if err != nil {
return types.SignedHeader{}, err
}
return decodeOptimisticHeadUpdate(resp)
}
func decodeOptimisticHeadUpdate(enc []byte) (types.SignedHeader, error) {
var data struct {
Data struct {
Header jsonBeaconHeader `json:"attested_header"`
Aggregate types.SyncAggregate `json:"sync_aggregate"`
SignatureSlot common.Decimal `json:"signature_slot"`
} `json:"data"`
}
if err := json.Unmarshal(enc, &data); err != nil {
return types.SignedHeader{}, err
}
if data.Data.Header.Beacon.StateRoot == (common.Hash{}) {
// workaround for different event encoding format in Lodestar
if err := json.Unmarshal(enc, &data.Data); err != nil {
return types.SignedHeader{}, err
}
}
if len(data.Data.Aggregate.Signers) != params.SyncCommitteeBitmaskSize {
return types.SignedHeader{}, errors.New("invalid sync_committee_bits length")
}
if len(data.Data.Aggregate.Signature) != params.BLSSignatureSize {
return types.SignedHeader{}, errors.New("invalid sync_committee_signature length")
}
return types.SignedHeader{
Header: data.Data.Header.Beacon,
Signature: data.Data.Aggregate,
SignatureSlot: uint64(data.Data.SignatureSlot),
}, nil
}
// GetFinalityUpdate fetches the latest available finality update.
//
// See data structure definition here:
// https://github.com/ethereum/consensus-specs/blob/dev/specs/altair/light-client/sync-protocol.md#lightclientfinalityupdate
func (api *BeaconLightApi) GetFinalityUpdate() (types.FinalityUpdate, error) {
resp, err := api.httpGet("/eth/v1/beacon/light_client/finality_update")
if err != nil {
return types.FinalityUpdate{}, err
}
return decodeFinalityUpdate(resp)
}
func decodeFinalityUpdate(enc []byte) (types.FinalityUpdate, error) {
var data struct {
Version string
Data struct {
Attested jsonHeaderWithExecProof `json:"attested_header"`
Finalized jsonHeaderWithExecProof `json:"finalized_header"`
FinalityBranch merkle.Values `json:"finality_branch"`
Aggregate types.SyncAggregate `json:"sync_aggregate"`
SignatureSlot common.Decimal `json:"signature_slot"`
}
}
if err := json.Unmarshal(enc, &data); err != nil {
return types.FinalityUpdate{}, err
}
// Decode the execution payload headers.
attestedExecHeader, err := types.ExecutionHeaderFromJSON(data.Version, data.Data.Attested.Execution)
if err != nil {
return types.FinalityUpdate{}, fmt.Errorf("invalid attested header: %v", err)
}
finalizedExecHeader, err := types.ExecutionHeaderFromJSON(data.Version, data.Data.Finalized.Execution)
if err != nil {
return types.FinalityUpdate{}, fmt.Errorf("invalid finalized header: %v", err)
}
// Perform sanity checks.
if len(data.Data.Aggregate.Signers) != params.SyncCommitteeBitmaskSize {
return types.FinalityUpdate{}, errors.New("invalid sync_committee_bits length")
}
if len(data.Data.Aggregate.Signature) != params.BLSSignatureSize {
return types.FinalityUpdate{}, errors.New("invalid sync_committee_signature length")
}
return types.FinalityUpdate{
Attested: types.HeaderWithExecProof{
Header: data.Data.Attested.Beacon,
PayloadHeader: attestedExecHeader,
PayloadBranch: data.Data.Attested.ExecutionBranch,
},
Finalized: types.HeaderWithExecProof{
Header: data.Data.Finalized.Beacon,
PayloadHeader: finalizedExecHeader,
PayloadBranch: data.Data.Finalized.ExecutionBranch,
},
FinalityBranch: data.Data.FinalityBranch,
Signature: data.Data.Aggregate,
SignatureSlot: uint64(data.Data.SignatureSlot),
}, nil
}
// GetHead fetches and validates the beacon header with the given blockRoot.
// If blockRoot is null hash then the latest head header is fetched.
func (api *BeaconLightApi) GetHeader(blockRoot common.Hash) (types.Header, error) {
var blockId string
if blockRoot == (common.Hash{}) {
blockId = "head"
} else {
blockId = blockRoot.Hex()
}
resp, err := api.httpGetf("/eth/v1/beacon/headers/%s", blockId)
if err != nil {
return types.Header{}, err
}
var data struct {
Data struct {
Root common.Hash `json:"root"`
Canonical bool `json:"canonical"`
Header struct {
Message types.Header `json:"message"`
Signature hexutil.Bytes `json:"signature"`
} `json:"header"`
} `json:"data"`
}
if err := json.Unmarshal(resp, &data); err != nil {
return types.Header{}, err
}
header := data.Data.Header.Message
if blockRoot == (common.Hash{}) {
blockRoot = data.Data.Root
}
if header.Hash() != blockRoot {
return types.Header{}, errors.New("retrieved beacon header root does not match")
}
return header, nil
}
// GetCheckpointData fetches and validates bootstrap data belonging to the given checkpoint.
func (api *BeaconLightApi) GetCheckpointData(checkpointHash common.Hash) (*types.BootstrapData, error) {
resp, err := api.httpGetf("/eth/v1/beacon/light_client/bootstrap/0x%x", checkpointHash[:])
if err != nil {
return nil, err
}
// See data structure definition here:
// https://github.com/ethereum/consensus-specs/blob/dev/specs/altair/light-client/sync-protocol.md#lightclientbootstrap
type bootstrapData struct {
Data struct {
Header jsonBeaconHeader `json:"header"`
Committee *types.SerializedSyncCommittee `json:"current_sync_committee"`
CommitteeBranch merkle.Values `json:"current_sync_committee_branch"`
} `json:"data"`
}
var data bootstrapData
if err := json.Unmarshal(resp, &data); err != nil {
return nil, err
}
if data.Data.Committee == nil {
return nil, errors.New("sync committee is missing")
}
header := data.Data.Header.Beacon
if header.Hash() != checkpointHash {
return nil, fmt.Errorf("invalid checkpoint block header, have %v want %v", header.Hash(), checkpointHash)
}
checkpoint := &types.BootstrapData{
Header: header,
CommitteeBranch: data.Data.CommitteeBranch,
CommitteeRoot: data.Data.Committee.Root(),
Committee: data.Data.Committee,
}
if err := checkpoint.Validate(); err != nil {
return nil, fmt.Errorf("invalid checkpoint: %w", err)
}
if checkpoint.Header.Hash() != checkpointHash {
return nil, errors.New("wrong checkpoint hash")
}
return checkpoint, nil
}
func (api *BeaconLightApi) GetBeaconBlock(blockRoot common.Hash) (*types.BeaconBlock, error) {
resp, err := api.httpGetf("/eth/v2/beacon/blocks/0x%x", blockRoot)
if err != nil {
return nil, err
}
var beaconBlockMessage struct {
Version string
Data struct {
Message json.RawMessage `json:"message"`
}
}
if err := json.Unmarshal(resp, &beaconBlockMessage); err != nil {
return nil, fmt.Errorf("invalid block json data: %v", err)
}
block, err := types.BlockFromJSON(beaconBlockMessage.Version, beaconBlockMessage.Data.Message)
if err != nil {
return nil, err
}
computedRoot := block.Root()
if computedRoot != blockRoot {
return nil, fmt.Errorf("Beacon block root hash mismatch (expected: %x, got: %x)", blockRoot, computedRoot)
}
return block, nil
}
func decodeHeadEvent(enc []byte) (uint64, common.Hash, error) {
var data struct {
Slot common.Decimal `json:"slot"`
Block common.Hash `json:"block"`
}
if err := json.Unmarshal(enc, &data); err != nil {
return 0, common.Hash{}, err
}
return uint64(data.Slot), data.Block, nil
}
type HeadEventListener struct {
OnNewHead func(slot uint64, blockRoot common.Hash)
OnSignedHead func(head types.SignedHeader)
OnFinality func(head types.FinalityUpdate)
OnError func(err error)
}
// StartHeadListener creates an event subscription for heads and signed (optimistic)
// head updates and calls the specified callback functions when they are received.
// The callbacks are also called for the current head and optimistic head at startup.
// They are never called concurrently.
func (api *BeaconLightApi) StartHeadListener(listener HeadEventListener) func() {
closeCh := make(chan struct{}) // initiate closing the stream
closedCh := make(chan struct{}) // stream closed (or failed to create)
stoppedCh := make(chan struct{}) // sync loop stopped
streamCh := make(chan *eventsource.Stream, 1)
go func() {
defer close(closedCh)
// when connected to a Lodestar node the subscription blocks until the
// first actual event arrives; therefore we create the subscription in
// a separate goroutine while letting the main goroutine sync up to the
// current head
req, err := http.NewRequest("GET", api.url+
"/eth/v1/events?topics=head&topics=light_client_optimistic_update&topics=light_client_finality_update", nil)
if err != nil {
listener.OnError(fmt.Errorf("error creating event subscription request: %v", err))
return
}
for k, v := range api.customHeaders {
req.Header.Set(k, v)
}
stream, err := eventsource.SubscribeWithRequest("", req)
if err != nil {
listener.OnError(fmt.Errorf("error creating event subscription: %v", err))
close(streamCh)
return
}
streamCh <- stream
<-closeCh
stream.Close()
}()
go func() {
defer close(stoppedCh)
if head, err := api.GetHeader(common.Hash{}); err == nil {
listener.OnNewHead(head.Slot, head.Hash())
}
if signedHead, err := api.GetOptimisticHeadUpdate(); err == nil {
listener.OnSignedHead(signedHead)
}
if finalityUpdate, err := api.GetFinalityUpdate(); err == nil {
listener.OnFinality(finalityUpdate)
}
stream := <-streamCh
if stream == nil {
return
}
for {
select {
case event, ok := <-stream.Events:
if !ok {
return
}
switch event.Event() {
case "head":
if slot, blockRoot, err := decodeHeadEvent([]byte(event.Data())); err == nil {
listener.OnNewHead(slot, blockRoot)
} else {
listener.OnError(fmt.Errorf("error decoding head event: %v", err))
}
case "light_client_optimistic_update":
if signedHead, err := decodeOptimisticHeadUpdate([]byte(event.Data())); err == nil {
listener.OnSignedHead(signedHead)
} else {
listener.OnError(fmt.Errorf("error decoding optimistic update event: %v", err))
}
case "light_client_finality_update":
if finalityUpdate, err := decodeFinalityUpdate([]byte(event.Data())); err == nil {
listener.OnFinality(finalityUpdate)
} else {
listener.OnError(fmt.Errorf("error decoding finality update event: %v", err))
}
default:
listener.OnError(fmt.Errorf("unexpected event: %s", event.Event()))
}
case err, ok := <-stream.Errors:
if !ok {
return
}
listener.OnError(err)
}
}
}()
return func() {
close(closeCh)
<-closedCh
<-stoppedCh
}
}