Merge pull request #82 from GrapeBaBa/portal1

feat:light client init bootstrap

portalnetwork/beacon/light_client.go

@@ -1,8 +1,16 @@
 package beacon
 
 import (
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/protolambda/zrnt/eth2/beacon/altair"
 	"github.com/protolambda/zrnt/eth2/beacon/capella"
 	"github.com/protolambda/zrnt/eth2/beacon/common"
+	"github.com/protolambda/zrnt/eth2/util/merkle"
+	"github.com/protolambda/ztyp/tree"
 	"github.com/protolambda/ztyp/view"
 )
 
@@ -30,6 +38,7 @@ type ConsensusLightClient struct {
 	InitialCheckpoint common.Root
 	LastCheckpoint    common.Root
 	Config            Config
+	Logger            log.Logger
 }
 
 type Config struct {
@@ -51,3 +60,78 @@ type ChainConfig struct {
 	GenesisTime uint64
 	GenesisRoot common.Root
 }
+
+//lint:ignore U1000 placeholder function
+func (c *ConsensusLightClient) bootstrap() error {
+	bootstrap, err := c.API.GetCheckpointData(c.InitialCheckpoint)
+	if err != nil {
+		return err
+	}
+
+	isValid := c.isValidCheckpoint(bootstrap.Header.Beacon.Slot)
+	if !isValid {
+		if c.Config.StrictCheckpointAge {
+			return errors.New("checkpoint is too old")
+		} else {
+			c.Logger.Warn("checkpoint is too old")
+		}
+	}
+
+	committeeValid := c.isCurrentCommitteeProofValid(bootstrap.Header.Beacon, bootstrap.CurrentSyncCommittee, bootstrap.CurrentSyncCommitteeBranch)
+
+	headerHash := bootstrap.Header.Beacon.HashTreeRoot(tree.GetHashFn()).String()
+	expectedHash := c.InitialCheckpoint.String()
+
+	headerValid := headerHash == expectedHash
+
+	if !headerValid {
+		return fmt.Errorf("header hash %s does not match expected hash %s", headerHash, expectedHash)
+	}
+
+	if !committeeValid {
+		return errors.New("committee proof is invalid")
+	}
+
+	c.Store = LightClientStore{
+		FinalizedHeader:               bootstrap.Header.Beacon,
+		CurrentSyncCommittee:          bootstrap.CurrentSyncCommittee,
+		OptimisticHeader:              bootstrap.Header.Beacon,
+		PreviousMaxActiveParticipants: view.Uint64View(0),
+		CurrentMaxActiveParticipants:  view.Uint64View(0),
+	}
+
+	return nil
+}
+
+func (c *ConsensusLightClient) isValidCheckpoint(blockHashSlot common.Slot) bool {
+	currentSlot := c.expectedCurrentSlot()
+	currentSlotTimestamp, err := c.slotTimestamp(currentSlot)
+	if err != nil {
+		return false
+	}
+	blockHashSlotTimestamp, err := c.slotTimestamp(blockHashSlot)
+	if err != nil {
+		return false
+	}
+
+	slotAge := currentSlotTimestamp - blockHashSlotTimestamp
+
+	return uint64(slotAge) < c.Config.MaxCheckpointAge
+}
+
+func (c *ConsensusLightClient) expectedCurrentSlot() common.Slot {
+	return c.Config.Spec.TimeToSlot(common.Timestamp(time.Now().Unix()), common.Timestamp(c.Config.ChainConfig.GenesisTime))
+}
+
+func (c *ConsensusLightClient) slotTimestamp(slot common.Slot) (common.Timestamp, error) {
+	atSlot, err := c.Config.Spec.TimeAtSlot(slot, common.Timestamp(c.Config.ChainConfig.GenesisTime))
+	if err != nil {
+		return 0, err
+	}
+
+	return atSlot, nil
+}
+
+func (c *ConsensusLightClient) isCurrentCommitteeProofValid(attestedHeader common.BeaconBlockHeader, currentCommittee common.SyncCommittee, currentCommitteeBranch altair.SyncCommitteeProofBranch) bool {
+	return merkle.VerifyMerkleBranch(currentCommittee.HashTreeRoot(c.Config.Spec, tree.GetHashFn()), currentCommitteeBranch[:], 5, 22, attestedHeader.StateRoot)
+}