@lodestar/beacon-node/src/util/graffiti.ts

A Typescript implementation of the beacon chain

import {Bytes32} from "@lodestar/types";
import {GRAFFITI_SIZE} from "../constants/index.js";
import {ClientVersion} from "../execution/index.js";

/**
 * Parses a graffiti UTF8 string and returns a 32 bytes buffer right padded with zeros
 */
export function toGraffitiBytes(graffiti: string): Bytes32 {
  return Buffer.concat([Buffer.from(graffiti, "utf8"), Buffer.alloc(GRAFFITI_SIZE, 0)], GRAFFITI_SIZE);
}

/**
 * Converts a graffiti from 32 bytes buffer back to a UTF-8 string
 */
export function fromGraffitiBytes(graffiti: Bytes32): string {
  return Buffer.from(graffiti.buffer, graffiti.byteOffset, graffiti.byteLength)
    .toString("utf8")
    .replaceAll("\u0000", "");
}

export function getDefaultGraffiti(
  consensusClientVersion: ClientVersion,
  executionClientVersion: ClientVersion | null | undefined,
  opts: {private?: boolean}
): string {
  if (opts.private) {
    return "";
  }

  if (executionClientVersion != null) {
    const {code: executionCode, commit: executionCommit} = executionClientVersion;

    // Follow the 2-byte commit format in https://github.com/ethereum/execution-apis/pull/517#issuecomment-1918512560
    return `${executionCode}${executionCommit.slice(0, 4)}${consensusClientVersion.code}${consensusClientVersion.commit.slice(0, 4)}`;
  }

  // No EL client info available. We still want to include CL info albeit not spec compliant
  return `${consensusClientVersion.code}${consensusClientVersion.commit.slice(0, 4)}`;
}