mirror of
https://gitlab.com/pulsechaincom/prysm-pulse.git
synced 2024-12-29 06:37:17 +00:00
84 lines
3.2 KiB
Go
84 lines
3.2 KiB
Go
package helpers
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import (
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"fmt"
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pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
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"github.com/prysmaticlabs/prysm/shared/hashutil"
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"github.com/prysmaticlabs/prysm/shared/params"
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)
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// GenerateSeed generates the randao seed of a given epoch.
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//
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// Spec pseudocode definition:
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// def generate_seed(state: BeaconState,
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// epoch: Epoch) -> Bytes32:
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// """
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// Generate a seed for the given ``epoch``.
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// """
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// return hash(
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// get_randao_mix(state, epoch - MIN_SEED_LOOKAHED) +
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// get_active_index_root(state, epoch)
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// )
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func GenerateSeed(state *pb.BeaconState, wantedEpoch uint64) ([32]byte, error) {
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if wantedEpoch > params.BeaconConfig().MinSeedLookahead {
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wantedEpoch -= params.BeaconConfig().MinSeedLookahead
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}
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randaoMix, err := RandaoMix(state, wantedEpoch)
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if err != nil {
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return [32]byte{}, err
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}
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indexRoot, err := ActiveIndexRoot(state, wantedEpoch)
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if err != nil {
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return [32]byte{}, err
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}
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return hashutil.Hash(append(randaoMix, indexRoot...)), nil
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}
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// ActiveIndexRoot returns the index root of a given epoch.
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//
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// Spec pseudocode definition:
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// def get_active_index_root(state: BeaconState,
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// epoch: Epoch) -> Bytes32:
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// """
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// Return the index root at a recent ``epoch``.
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// """
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// assert get_current_epoch(state) - LATEST_INDEX_ROOTS_LENGTH + ACTIVATION_EXIT_DELAY < epoch <= get_current_epoch(state) + ACTIVATION_EXIT_DELAY
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// return state.latest_index_roots[epoch % LATEST_INDEX_ROOTS_LENGTH]
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func ActiveIndexRoot(state *pb.BeaconState, wantedEpoch uint64) ([]byte, error) {
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var earliestEpoch uint64
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currentEpoch := CurrentEpoch(state)
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if currentEpoch > params.BeaconConfig().LatestActiveIndexRootsLength+params.BeaconConfig().ActivationExitDelay {
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earliestEpoch = currentEpoch - (params.BeaconConfig().LatestActiveIndexRootsLength + params.BeaconConfig().ActivationExitDelay)
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}
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if earliestEpoch > wantedEpoch || wantedEpoch > currentEpoch {
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return nil, fmt.Errorf("input indexRoot epoch %d out of bounds: %d <= epoch < %d",
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wantedEpoch, earliestEpoch, currentEpoch)
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}
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return state.LatestIndexRootHash32S[wantedEpoch%params.BeaconConfig().LatestActiveIndexRootsLength], nil
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}
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// RandaoMix returns the randao mix (xor'ed seed)
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// of a given slot. It is used to shuffle validators.
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//
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// Spec pseudocode definition:
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// def get_randao_mix(state: BeaconState,
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// epoch: Epoch) -> Bytes32:
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// """
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// Return the randao mix at a recent ``epoch``.
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// """
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// assert get_current_epoch(state) - LATEST_RANDAO_MIXES_LENGTH < epoch <= get_current_epoch(state)
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// return state.latest_randao_mixes[epoch % LATEST_RANDAO_MIXES_LENGTH]
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func RandaoMix(state *pb.BeaconState, wantedEpoch uint64) ([]byte, error) {
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var earliestEpoch uint64
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currentEpoch := CurrentEpoch(state)
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if currentEpoch > params.BeaconConfig().LatestRandaoMixesLength {
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earliestEpoch = currentEpoch - params.BeaconConfig().LatestRandaoMixesLength
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}
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if earliestEpoch > wantedEpoch || wantedEpoch > currentEpoch {
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return nil, fmt.Errorf("input randaoMix epoch %d out of bounds: %d <= epoch < %d",
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wantedEpoch, earliestEpoch, currentEpoch)
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}
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return state.LatestRandaoMixes[wantedEpoch%params.BeaconConfig().LatestRandaoMixesLength], nil
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}
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