@lodestar/beacon-node/lib/chain/opPools/utils.js

A Typescript implementation of the beacon chain

import { Signature } from "@chainsafe/blst";
import { BLS_WITHDRAWAL_PREFIX } from "@lodestar/params";
/**
 * Prune a Map indexed by slot to keep the most recent slots, up to `slotsRetained`
 */
export function pruneBySlot(map, slot, slotsRetained) {
    const lowestPermissibleSlot = Math.max(slot - slotsRetained, 0);
    // No need to prune if the lowest permissible slot has not changed and the queue length is less than the maximum
    if (map.size <= slotsRetained) {
        return lowestPermissibleSlot;
    }
    // Remove the oldest slots to keep a max of `slotsRetained` slots
    const slots = Array.from(map.keys());
    const slotsToDelete = slots.sort((a, b) => b - a).slice(slotsRetained);
    for (const slot of slotsToDelete) {
        map.delete(slot);
    }
    return lowestPermissibleSlot;
}
/**
 * De-serialize bytes into Signature.
 * No need to verify Signature is valid, already run sig-verify = false
 */
export function signatureFromBytesNoCheck(signature) {
    return Signature.fromBytes(signature);
}
/**
 * Ensures that a SignedBLSToExecutionChange object is _still_ valid for block inclusion. An object valid for the pool,
 * can become invalid for certain forks.
 */
export function isValidBlsToExecutionChangeForBlockInclusion(state, signedBLSToExecutionChange) {
    // For each condition from https://github.com/ethereum/consensus-specs/blob/dev/specs/capella/beacon-chain.md#new-process_bls_to_execution_change
    //
    // 1. assert address_change.validator_index < len(state.validators):
    //    If valid before will always be valid in the future, no need to check
    //
    // 2. assert validator.withdrawal_credentials[:1] == BLS_WITHDRAWAL_PREFIX:
    //    Must be checked again, since it can already be changed by now.
    const validator = state.validators.getReadonly(signedBLSToExecutionChange.message.validatorIndex);
    const { withdrawalCredentials } = validator;
    if (withdrawalCredentials[0] !== BLS_WITHDRAWAL_PREFIX) {
        return false;
    }
    // 3. assert validator.withdrawal_credentials[1:] == hash(address_change.from_bls_pubkey)[1:]:
    //    If valid before will always be valid in the future, no need to check
    return true;
}
export function isElectraAggregate(aggregate) {
    return aggregate.committeeBits !== undefined;
}
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