prysm-pulse/beacon-chain/sync/validate_voluntary_exit.go

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package sync
import (
"context"
"fmt"
"github.com/gogo/protobuf/proto"
"github.com/karlseguin/ccache"
"github.com/pkg/errors"
ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
"github.com/prysmaticlabs/prysm/beacon-chain/core/state"
"github.com/prysmaticlabs/prysm/beacon-chain/p2p"
"github.com/prysmaticlabs/prysm/shared/params"
)
// seenExits tracks exits we've already seen to prevent feedback loop.
var seenExits = ccache.New(ccache.Configure())
func exitCacheKey(exit *ethpb.VoluntaryExit) string {
return fmt.Sprintf("%d-%d", exit.Epoch, exit.ValidatorIndex)
}
// Clients who receive a voluntary exit on this topic MUST validate the conditions within process_voluntary_exit before
// forwarding it across the network.
func (r *RegularSync) validateVoluntaryExit(ctx context.Context, msg proto.Message, p p2p.Broadcaster, fromSelf bool) (bool, error) {
// The head state will be too far away to validate any voluntary exit.
if r.initialSync.Syncing() {
return false, nil
}
exit, ok := msg.(*ethpb.VoluntaryExit)
if !ok {
return false, nil
}
cacheKey := exitCacheKey(exit)
invalidKey := invalid + cacheKey
if seenExits.Get(invalidKey) != nil {
return false, errors.New("previously seen invalid validator exit received")
}
if seenExits.Get(cacheKey) != nil {
return false, nil
}
// Retrieve head state, advance state to the epoch slot used specified in exit message.
s, err := r.chain.HeadState(ctx)
if err != nil {
return false, err
}
exitedEpochSlot := exit.Epoch * params.BeaconConfig().SlotsPerEpoch
if s.Slot < exitedEpochSlot {
var err error
s, err = state.ProcessSlots(ctx, s, exitedEpochSlot)
if err != nil {
return false, errors.Wrapf(err, "Failed to advance state to slot %d", exitedEpochSlot)
}
}
if err := blocks.VerifyExit(s, exit); err != nil {
seenExits.Set(invalidKey, true /*value*/, oneYear /*TTL*/)
return false, errors.Wrap(err, "Received invalid validator exit")
}
seenExits.Set(cacheKey, true /*value*/, oneYear /*TTL*/)
if fromSelf {
return false, nil
}
if err := p.Broadcast(ctx, exit); err != nil {
log.WithError(err).Error("Failed to propagate voluntary exit")
}
return true, nil
}