@web3-storage/car-block-validator/esm/src/index.js

Validate car block bytes

import {
  sha256,
  sha512
} from 'multiformats/hashes/sha2';
import {
  murmur3128,
  murmur332
} from '@multiformats/murmur3';
import { blake2b256 } from '@multiformats/blake2/blake2b';
import { blake2s256 } from '@multiformats/blake2/blake2s';
import {
  sha3224,
  sha3256,
  sha3384,
  sha3512,
  shake128,
  shake256,
  keccak224,
  keccak256,
  keccak384,
  keccak512
} from '@multiformats/sha3';
import { equals } from 'uint8arrays/equals';
export const hashMap = new Map([
  sha256,
  sha512,
  murmur3128,
  murmur332,
  blake2b256,
  blake2s256,
  sha3224,
  sha3256,
  sha3384,
  sha3512,
  shake128,
  shake256,
  keccak224,
  keccak256,
  keccak384,
  keccak512
].map(hash => [
  hash.code,
  hash
]));
export class UnsupportedHashError extends Error {
  constructor(code) {
    super(`multihash code ${ code } is not supported`);
  }
}
export class HashMismatchError extends Error {
  constructor() {
    super('CID hash does not match bytes');
  }
}
export function validateBlock(block) {
  const hasher = hashMap.get(block.cid.multihash.code);
  if (!hasher) {
    throw new UnsupportedHashError(block.cid.multihash.code);
  }
  const result = hasher.digest(block.bytes);
  const compareDigests = h => {
    if (!equals(h.digest, block.cid.multihash.digest)) {
      throw new HashMismatchError();
    }
  };
  if (result instanceof Promise) {
    return result.then(compareDigests);
  }
  compareDigests(result);
}