225 lines
5.4 KiB
Go
225 lines
5.4 KiB
Go
package drand
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import (
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"context"
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"math/rand"
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"sync"
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"time"
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"github.com/filecoin-project/lotus/build"
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"github.com/filecoin-project/lotus/chain/beacon"
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"github.com/filecoin-project/lotus/chain/types"
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"github.com/filecoin-project/specs-actors/actors/abi"
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"golang.org/x/xerrors"
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logging "github.com/ipfs/go-log"
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dbeacon "github.com/drand/drand/beacon"
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"github.com/drand/drand/core"
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dkey "github.com/drand/drand/key"
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dnet "github.com/drand/drand/net"
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dproto "github.com/drand/drand/protobuf/drand"
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)
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var log = logging.Logger("drand")
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var drandServers = []string{
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"nicolas.drand.fil-test.net:443",
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"philipp.drand.fil-test.net:443",
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"mathilde.drand.fil-test.net:443",
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"ludovic.drand.fil-test.net:443",
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"gabbi.drand.fil-test.net:443",
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"linus.drand.fil-test.net:443",
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"jeff.drand.fil-test.net:443",
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}
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var drandPubKey *dkey.DistPublic
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func init() {
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drandPubKey = new(dkey.DistPublic)
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err := drandPubKey.FromTOML(&dkey.DistPublicTOML{Coefficients: build.DrandCoeffs})
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if err != nil {
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panic(err)
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}
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}
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type drandPeer struct {
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addr string
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tls bool
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}
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func (dp *drandPeer) Address() string {
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return dp.addr
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}
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func (dp *drandPeer) IsTLS() bool {
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return dp.tls
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}
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type DrandBeacon struct {
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client dnet.Client
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peers []dnet.Peer
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peersIndex int
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peersIndexMtx sync.Mutex
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pubkey *dkey.DistPublic
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// seconds
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interval time.Duration
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drandGenTime uint64
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filGenTime uint64
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filRoundTime uint64
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cacheLk sync.Mutex
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localCache map[uint64]types.BeaconEntry
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}
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func NewDrandBeacon(genesisTs, interval uint64) (*DrandBeacon, error) {
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if genesisTs == 0 {
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panic("what are you doing this cant be zero")
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}
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db := &DrandBeacon{
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client: dnet.NewGrpcClient(),
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localCache: make(map[uint64]types.BeaconEntry),
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}
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for _, ds := range drandServers {
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db.peers = append(db.peers, &drandPeer{addr: ds, tls: true})
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}
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db.peersIndex = rand.Intn(len(db.peers))
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groupResp, err := db.client.Group(context.TODO(), db.peers[db.peersIndex], &dproto.GroupRequest{})
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if err != nil {
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return nil, xerrors.Errorf("failed to get group response from beacon peer: %w", err)
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}
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kgroup, err := core.ProtoToGroup(groupResp)
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if err != nil {
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return nil, xerrors.Errorf("failed to parse group response: %w", err)
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}
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// TODO: verify these values are what we expect them to be
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if !kgroup.PublicKey.Equal(drandPubKey) {
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return nil, xerrors.Errorf("public key does not match")
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}
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// fmt.Printf("Drand Pubkey:\n%#v\n", kgroup.PublicKey.TOML()) // use to print public key
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db.pubkey = drandPubKey
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db.interval = kgroup.Period
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db.drandGenTime = uint64(kgroup.GenesisTime)
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db.filRoundTime = interval
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db.filGenTime = genesisTs
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// TODO: the stream currently gives you back *all* values since drand genesis.
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// Having the stream in the background is merely an optimization, so not a big deal to disable it for now
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// go db.handleStreamingUpdates()
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return db, nil
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}
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func (db *DrandBeacon) rotatePeersIndex() {
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db.peersIndexMtx.Lock()
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defer db.peersIndexMtx.Unlock()
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db.peersIndex = (db.peersIndex + 1) % len(db.peers)
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}
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func (db *DrandBeacon) handleStreamingUpdates() {
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for {
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ch, err := db.client.PublicRandStream(context.Background(), db.peers[db.peersIndex], &dproto.PublicRandRequest{})
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if err != nil {
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log.Warnf("failed to get public rand stream: %s", err)
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log.Warnf("trying again in 10 seconds")
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db.rotatePeersIndex()
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time.Sleep(time.Second * 10)
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continue
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}
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for e := range ch {
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db.cacheValue(types.BeaconEntry{
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Round: e.Round,
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Data: e.Signature,
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})
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}
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log.Warn("drand beacon stream broke, reconnecting in 10 seconds")
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db.rotatePeersIndex()
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time.Sleep(time.Second * 10)
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}
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}
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func (db *DrandBeacon) Entry(ctx context.Context, round uint64) <-chan beacon.Response {
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// check cache, it it if there, otherwise query the endpoint
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cres := db.getCachedValue(round)
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if cres != nil {
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out := make(chan beacon.Response, 1)
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out <- beacon.Response{Entry: *cres}
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close(out)
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return out
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}
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out := make(chan beacon.Response, 1)
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go func() {
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resp, err := db.client.PublicRand(ctx, db.peers[db.peersIndex], &dproto.PublicRandRequest{Round: round})
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var br beacon.Response
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if err != nil {
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db.rotatePeersIndex()
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br.Err = err
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} else {
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br.Entry.Round = resp.GetRound()
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br.Entry.Data = resp.GetSignature()
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}
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out <- br
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close(out)
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}()
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return out
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}
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func (db *DrandBeacon) cacheValue(e types.BeaconEntry) {
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db.cacheLk.Lock()
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defer db.cacheLk.Unlock()
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db.localCache[e.Round] = e
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}
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func (db *DrandBeacon) getCachedValue(round uint64) *types.BeaconEntry {
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db.cacheLk.Lock()
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defer db.cacheLk.Unlock()
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v, ok := db.localCache[round]
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if !ok {
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return nil
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}
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return &v
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}
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func (db *DrandBeacon) VerifyEntry(curr types.BeaconEntry, prev types.BeaconEntry) error {
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if prev.Round == 0 {
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// TODO handle genesis better
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return nil
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}
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b := &dbeacon.Beacon{
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PreviousRound: prev.Round,
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PreviousSig: prev.Data,
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Round: curr.Round,
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Signature: curr.Data,
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}
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//log.Warnw("VerifyEntry", "beacon", b)
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err := dbeacon.VerifyBeacon(db.pubkey.Key(), b)
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if err == nil {
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db.cacheValue(curr)
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}
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return err
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}
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func (db *DrandBeacon) MaxBeaconRoundForEpoch(filEpoch abi.ChainEpoch, prevEntry types.BeaconEntry) uint64 {
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// TODO: sometimes the genesis time for filecoin is zero and this goes negative
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latestTs := ((uint64(filEpoch) * db.filRoundTime) + db.filGenTime) - db.filRoundTime
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dround := (latestTs - db.drandGenTime) / uint64(db.interval.Seconds())
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return dround
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}
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var _ beacon.RandomBeacon = (*DrandBeacon)(nil)
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