crc32c.ts

// Copyright 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import {PathLike, createReadStream} from 'fs';

/**
 * Ported from {@link https://github.com/google/crc32c/blob/21fc8ef30415a635e7351ffa0e5d5367943d4a94/src/crc32c_portable.cc#L16-L59 github.com/google/crc32c}
 */
const CRC32C_EXTENSIONS = [
  0x00000000, 0xf26b8303, 0xe13b70f7, 0x1350f3f4, 0xc79a971f, 0x35f1141c,
  0x26a1e7e8, 0xd4ca64eb, 0x8ad958cf, 0x78b2dbcc, 0x6be22838, 0x9989ab3b,
  0x4d43cfd0, 0xbf284cd3, 0xac78bf27, 0x5e133c24, 0x105ec76f, 0xe235446c,
  0xf165b798, 0x030e349b, 0xd7c45070, 0x25afd373, 0x36ff2087, 0xc494a384,
  0x9a879fa0, 0x68ec1ca3, 0x7bbcef57, 0x89d76c54, 0x5d1d08bf, 0xaf768bbc,
  0xbc267848, 0x4e4dfb4b, 0x20bd8ede, 0xd2d60ddd, 0xc186fe29, 0x33ed7d2a,
  0xe72719c1, 0x154c9ac2, 0x061c6936, 0xf477ea35, 0xaa64d611, 0x580f5512,
  0x4b5fa6e6, 0xb93425e5, 0x6dfe410e, 0x9f95c20d, 0x8cc531f9, 0x7eaeb2fa,
  0x30e349b1, 0xc288cab2, 0xd1d83946, 0x23b3ba45, 0xf779deae, 0x05125dad,
  0x1642ae59, 0xe4292d5a, 0xba3a117e, 0x4851927d, 0x5b016189, 0xa96ae28a,
  0x7da08661, 0x8fcb0562, 0x9c9bf696, 0x6ef07595, 0x417b1dbc, 0xb3109ebf,
  0xa0406d4b, 0x522bee48, 0x86e18aa3, 0x748a09a0, 0x67dafa54, 0x95b17957,
  0xcba24573, 0x39c9c670, 0x2a993584, 0xd8f2b687, 0x0c38d26c, 0xfe53516f,
  0xed03a29b, 0x1f682198, 0x5125dad3, 0xa34e59d0, 0xb01eaa24, 0x42752927,
  0x96bf4dcc, 0x64d4cecf, 0x77843d3b, 0x85efbe38, 0xdbfc821c, 0x2997011f,
  0x3ac7f2eb, 0xc8ac71e8, 0x1c661503, 0xee0d9600, 0xfd5d65f4, 0x0f36e6f7,
  0x61c69362, 0x93ad1061, 0x80fde395, 0x72966096, 0xa65c047d, 0x5437877e,
  0x4767748a, 0xb50cf789, 0xeb1fcbad, 0x197448ae, 0x0a24bb5a, 0xf84f3859,
  0x2c855cb2, 0xdeeedfb1, 0xcdbe2c45, 0x3fd5af46, 0x7198540d, 0x83f3d70e,
  0x90a324fa, 0x62c8a7f9, 0xb602c312, 0x44694011, 0x5739b3e5, 0xa55230e6,
  0xfb410cc2, 0x092a8fc1, 0x1a7a7c35, 0xe811ff36, 0x3cdb9bdd, 0xceb018de,
  0xdde0eb2a, 0x2f8b6829, 0x82f63b78, 0x709db87b, 0x63cd4b8f, 0x91a6c88c,
  0x456cac67, 0xb7072f64, 0xa457dc90, 0x563c5f93, 0x082f63b7, 0xfa44e0b4,
  0xe9141340, 0x1b7f9043, 0xcfb5f4a8, 0x3dde77ab, 0x2e8e845f, 0xdce5075c,
  0x92a8fc17, 0x60c37f14, 0x73938ce0, 0x81f80fe3, 0x55326b08, 0xa759e80b,
  0xb4091bff, 0x466298fc, 0x1871a4d8, 0xea1a27db, 0xf94ad42f, 0x0b21572c,
  0xdfeb33c7, 0x2d80b0c4, 0x3ed04330, 0xccbbc033, 0xa24bb5a6, 0x502036a5,
  0x4370c551, 0xb11b4652, 0x65d122b9, 0x97baa1ba, 0x84ea524e, 0x7681d14d,
  0x2892ed69, 0xdaf96e6a, 0xc9a99d9e, 0x3bc21e9d, 0xef087a76, 0x1d63f975,
  0x0e330a81, 0xfc588982, 0xb21572c9, 0x407ef1ca, 0x532e023e, 0xa145813d,
  0x758fe5d6, 0x87e466d5, 0x94b49521, 0x66df1622, 0x38cc2a06, 0xcaa7a905,
  0xd9f75af1, 0x2b9cd9f2, 0xff56bd19, 0x0d3d3e1a, 0x1e6dcdee, 0xec064eed,
  0xc38d26c4, 0x31e6a5c7, 0x22b65633, 0xd0ddd530, 0x0417b1db, 0xf67c32d8,
  0xe52cc12c, 0x1747422f, 0x49547e0b, 0xbb3ffd08, 0xa86f0efc, 0x5a048dff,
  0x8ecee914, 0x7ca56a17, 0x6ff599e3, 0x9d9e1ae0, 0xd3d3e1ab, 0x21b862a8,
  0x32e8915c, 0xc083125f, 0x144976b4, 0xe622f5b7, 0xf5720643, 0x07198540,
  0x590ab964, 0xab613a67, 0xb831c993, 0x4a5a4a90, 0x9e902e7b, 0x6cfbad78,
  0x7fab5e8c, 0x8dc0dd8f, 0xe330a81a, 0x115b2b19, 0x020bd8ed, 0xf0605bee,
  0x24aa3f05, 0xd6c1bc06, 0xc5914ff2, 0x37faccf1, 0x69e9f0d5, 0x9b8273d6,
  0x88d28022, 0x7ab90321, 0xae7367ca, 0x5c18e4c9, 0x4f48173d, 0xbd23943e,
  0xf36e6f75, 0x0105ec76, 0x12551f82, 0xe03e9c81, 0x34f4f86a, 0xc69f7b69,
  0xd5cf889d, 0x27a40b9e, 0x79b737ba, 0x8bdcb4b9, 0x988c474d, 0x6ae7c44e,
  0xbe2da0a5, 0x4c4623a6, 0x5f16d052, 0xad7d5351,
] as const;

const CRC32C_EXTENSION_TABLE = new Int32Array(CRC32C_EXTENSIONS);

/** An interface for CRC32C hashing and validation */
interface CRC32CValidator {
  /**
   * A method returning the CRC32C as a base64-encoded string.
   *
   * @example
   * Hashing the string 'data' should return 'rth90Q=='
   *
   * ```js
   * const buffer = Buffer.from('data');
   * crc32c.update(buffer);
   * crc32c.toString(); // 'rth90Q=='
   * ```
   **/
  toString: () => string;
  /**
   * A method validating a base64-encoded CRC32C string.
   *
   * @example
   * Should return `true` if the value matches, `false` otherwise
   *
   * ```js
   * const buffer = Buffer.from('data');
   * crc32c.update(buffer);
   * crc32c.validate('DkjKuA=='); // false
   * crc32c.validate('rth90Q=='); // true
   * ```
   */
  validate: (value: string) => boolean;
  /**
   * A method for passing `Buffer`s for CRC32C generation.
   *
   * @example
   * Hashing buffers from 'some ' and 'text\n'
   *
   * ```js
   * const buffer1 = Buffer.from('some ');
   * crc32c.update(buffer1);
   *
   * const buffer2 = Buffer.from('text\n');
   * crc32c.update(buffer2);
   *
   * crc32c.toString(); // 'DkjKuA=='
   * ```
   */
  update: (data: Buffer) => void;
}

/** A function that generates a CRC32C Validator */
interface CRC32CValidatorGenerator {
  /** Should return a new, ready-to-use `CRC32CValidator` */
  (): CRC32CValidator;
}

const CRC32C_DEFAULT_VALIDATOR_GENERATOR: CRC32CValidatorGenerator = () =>
  new CRC32C();

const CRC32C_EXCEPTION_MESSAGES = {
  INVALID_INIT_BASE64_RANGE: (l: number) =>
    `base64-encoded data expected to equal 4 bytes, not ${l}`,
  INVALID_INIT_BUFFER_LENGTH: (l: number) =>
    `Buffer expected to equal 4 bytes, not ${l}`,
  INVALID_INIT_INTEGER: (l: number) =>
    `Number expected to be a safe, unsigned 32-bit integer, not ${l}`,
} as const;

class CRC32C implements CRC32CValidator {
  /** Current CRC32C value */
  #crc32c = 0;

  /**
   * Constructs a new `CRC32C` object.
   *
   * Reconstruction is recommended via the `CRC32C.from` static method.
   *
   * @param initialValue An initial CRC32C value - a signed 32-bit integer.
   */
  constructor(initialValue = 0) {
    this.#crc32c = initialValue;
  }

  /**
   * Calculates a CRC32C from a provided buffer.
   *
   * Implementation inspired from:
   * - {@link https://github.com/google/crc32c/blob/21fc8ef30415a635e7351ffa0e5d5367943d4a94/src/crc32c_portable.cc github.com/google/crc32c}
   * - {@link https://github.com/googleapis/python-crc32c/blob/a595e758c08df445a99c3bf132ee8e80a3ec4308/src/google_crc32c/python.py github.com/googleapis/python-crc32c}
   * - {@link https://github.com/googleapis/java-storage/pull/1376/files github.com/googleapis/java-storage}
   *
   * @param data The `Buffer` to generate the CRC32C from
   */
  update(data: Buffer) {
    let current = this.#crc32c ^ 0xffffffff;

    for (const d of data) {
      const tablePoly = CRC32C.CRC32C_EXTENSION_TABLE[(d ^ current) & 0xff];
      current = tablePoly ^ (current >>> 8);
    }

    this.#crc32c = current ^ 0xffffffff;
  }

  /**
   * Validates a provided input to the current CRC32C value.
   *
   * @param input A Buffer, `CRC32C`-compatible object, base64-encoded data (string), or signed 32-bit integer
   */
  validate(input: Buffer | CRC32CValidator | string | number): boolean {
    if (typeof input === 'number') {
      return input === this.#crc32c;
    } else if (typeof input === 'string') {
      return input === this.toString();
    } else if (Buffer.isBuffer(input)) {
      return Buffer.compare(input, this.toBuffer()) === 0;
    } else {
      // `CRC32C`-like object
      return input.toString() === this.toString();
    }
  }

  /**
   * Returns a `Buffer` representation of the CRC32C value
   */
  toBuffer(): Buffer {
    const buffer = Buffer.alloc(4);
    buffer.writeInt32BE(this.#crc32c);

    return buffer;
  }

  /**
   * Returns a JSON-compatible, base64-encoded representation of the CRC32C value.
   *
   * See {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify `JSON#stringify`}
   */
  toJSON(): string {
    return this.toString();
  }

  /**
   * Returns a base64-encoded representation of the CRC32C value.
   *
   * See {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/toString `Object#toString`}
   */
  toString(): string {
    return this.toBuffer().toString('base64');
  }

  /**
   * Returns the `number` representation of the CRC32C value as a signed 32-bit integer
   *
   * See {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/valueOf `Object#valueOf`}
   */
  valueOf(): number {
    return this.#crc32c;
  }

  static readonly CRC32C_EXTENSIONS = CRC32C_EXTENSIONS;
  static readonly CRC32C_EXTENSION_TABLE = CRC32C_EXTENSION_TABLE;

  /**
   * Generates a `CRC32C` from a compatible buffer format.
   *
   * @param value 4-byte `ArrayBufferView`/`Buffer`/`TypedArray`
   */
  private static fromBuffer(
    value: ArrayBuffer | ArrayBufferView | Buffer
  ): CRC32C {
    let buffer: Buffer;

    if (Buffer.isBuffer(value)) {
      buffer = value;
    } else if ('buffer' in value) {
      // `ArrayBufferView`
      buffer = Buffer.from(value.buffer);
    } else {
      // `ArrayBuffer`
      buffer = Buffer.from(value);
    }

    if (buffer.byteLength !== 4) {
      throw new RangeError(
        CRC32C_EXCEPTION_MESSAGES.INVALID_INIT_BUFFER_LENGTH(buffer.byteLength)
      );
    }

    return new CRC32C(buffer.readInt32BE());
  }

  static async fromFile(file: PathLike) {
    const crc32c = new CRC32C();

    await new Promise((resolve, reject) => {
      createReadStream(file)
        .on('data', (d: Buffer) => crc32c.update(d))
        .on('end', resolve)
        .on('error', reject);
    });

    return crc32c;
  }

  /**
   * Generates a `CRC32C` from 4-byte base64-encoded data (string).
   *
   * @param value 4-byte base64-encoded data (string)
   */
  private static fromString(value: string): CRC32C {
    const buffer = Buffer.from(value, 'base64');

    if (buffer.byteLength !== 4) {
      throw new RangeError(
        CRC32C_EXCEPTION_MESSAGES.INVALID_INIT_BASE64_RANGE(buffer.byteLength)
      );
    }

    return this.fromBuffer(buffer);
  }

  /**
   * Generates a `CRC32C` from a safe, unsigned 32-bit integer.
   *
   * @param value an unsigned 32-bit integer
   */
  private static fromNumber(value: number): CRC32C {
    if (!Number.isSafeInteger(value) || value > 2 ** 32 || value < -(2 ** 32)) {
      throw new RangeError(
        CRC32C_EXCEPTION_MESSAGES.INVALID_INIT_INTEGER(value)
      );
    }

    return new CRC32C(value);
  }

  /**
   * Generates a `CRC32C` from a variety of compatable types.
   * Note: strings are treated as input, not as file paths to read from.
   *
   * @param value A number, 4-byte `ArrayBufferView`/`Buffer`/`TypedArray`, or 4-byte base64-encoded data (string)
   */
  static from(
    value: ArrayBuffer | ArrayBufferView | CRC32CValidator | string | number
  ): CRC32C {
    if (typeof value === 'number') {
      return this.fromNumber(value);
    } else if (typeof value === 'string') {
      return this.fromString(value);
    } else if ('byteLength' in value) {
      // `ArrayBuffer` | `Buffer` | `ArrayBufferView`
      return this.fromBuffer(value);
    } else {
      // `CRC32CValidator`/`CRC32C`-like
      return this.fromString(value.toString());
    }
  }
}

export {
  CRC32C,
  CRC32C_DEFAULT_VALIDATOR_GENERATOR,
  CRC32C_EXCEPTION_MESSAGES,
  CRC32C_EXTENSIONS,
  CRC32C_EXTENSION_TABLE,
  CRC32CValidator,
  CRC32CValidatorGenerator,
};