prysm-pulse/beacon-chain/rpc/attester_server.go
Raul Jordan 3e46381b3f
Fetch the Correct Chain Head During AttestHead (#1596)
* correct attester view of chain head and prioritize proposer

* fix attempt not working

* revise with correct logic

* attester fixess to root fetching, spec did not make sense

* comments to match code

* fix attester responsibility

* comments
2019-02-18 23:49:56 -06:00

78 lines
3.5 KiB
Go

package rpc
import (
"context"
"fmt"
"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
"github.com/prysmaticlabs/prysm/beacon-chain/db"
pbp2p "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
pb "github.com/prysmaticlabs/prysm/proto/beacon/rpc/v1"
"github.com/prysmaticlabs/prysm/shared/hashutil"
"github.com/prysmaticlabs/prysm/shared/params"
"github.com/prysmaticlabs/prysm/shared/ssz"
)
// AttesterServer defines a server implementation of the gRPC Attester service,
// providing RPC methods for validators acting as attesters to broadcast votes on beacon blocks.
type AttesterServer struct {
beaconDB *db.BeaconDB
operationService operationService
}
// AttestHead is a function called by an attester in a sharding validator to vote
// on a block via an attestation object as defined in the Ethereum Serenity specification.
func (as *AttesterServer) AttestHead(ctx context.Context, att *pbp2p.Attestation) (*pb.AttestResponse, error) {
h, err := hashutil.HashProto(att)
if err != nil {
return nil, fmt.Errorf("could not hash attestation: %v", err)
}
// Relays the attestation to chain service.
as.operationService.IncomingAttFeed().Send(att)
return &pb.AttestResponse{AttestationHash: h[:]}, nil
}
// AttestationInfoAtSlot fetches the necessary information from the current canonical head
// and beacon state for an assigned attester to perform necessary responsibilities. This includes
// fetching the epoch boundary roots, the latest justified block root, among others.
func (as *AttesterServer) AttestationInfoAtSlot(ctx context.Context, req *pb.AttestationInfoRequest) (*pb.AttestationInfoResponse, error) {
// Set the attestation data's beacon block root = hash_tree_root(head) where head
// is the validator's view of the head block of the beacon chain during the slot.
head, err := as.beaconDB.ChainHead()
if err != nil {
return nil, fmt.Errorf("failed to retrieve chain head: %v", err)
}
blockRoot, err := ssz.TreeHash(head)
if err != nil {
return nil, fmt.Errorf("could not tree hash beacon block: %v", err)
}
beaconState, err := as.beaconDB.State()
if err != nil {
return nil, fmt.Errorf("could not fetch beacon state: %v", err)
}
// Fetch the epoch boundary root = hash_tree_root(epoch_boundary)
// where epoch_boundary is the block at the most recent epoch boundary in the
// chain defined by head -- i.e. the BeaconBlock where block.slot == get_epoch_start_slot(head.slot).
// On the server side, this is fetched by calling get_block_root(state, get_epoch_start_slot(head.slot)).
epochBoundary := head.Slot / params.BeaconConfig().SlotsPerEpoch
epochBoundaryRoot, err := blocks.BlockRoot(beaconState, helpers.StartSlot(epochBoundary))
if err != nil {
return nil, fmt.Errorf("could not get epoch boundary block: %v", err)
}
// Fetch the justified block root = hash_tree_root(justified_block) where
// justified_block is the block at state.justified_epoch in the chain defined by head.
// On the server side, this is fetched by calling get_block_root(state, justified_epoch).
justifiedBlockRoot, err := blocks.BlockRoot(beaconState, helpers.StartSlot(beaconState.JustifiedEpoch))
if err != nil {
return nil, fmt.Errorf("could not get justified block: %v", err)
}
return &pb.AttestationInfoResponse{
BeaconBlockRootHash32: blockRoot[:],
EpochBoundaryRootHash32: epochBoundaryRoot[:],
JustifiedEpoch: beaconState.JustifiedEpoch,
JustifiedBlockRootHash32: justifiedBlockRoot[:],
LatestCrosslink: beaconState.LatestCrosslinks[req.Shard],
}, nil
}