node-expose-sspi-strict/src/sso/misc.ts

Expose the Microsoft Windows SSPI interface in order to do NTLM and Kerberos authentication.

import dbg from 'debug';
import { decode } from 'base64-arraybuffer';
import { MessageType } from './interfaces';

const debug = dbg('node-expose-sspi:misc');

function isPrintable(keycode: number): boolean {
  const valid =
    (keycode > 47 && keycode < 58) || // number keys
    keycode === 32 || // spacebar & return key(s) (if you want to allow carriage returns)
    (keycode > 64 && keycode < 91) || // letter keys
    (keycode > 95 && keycode < 112) || // numpad keys
    (keycode > 185 && keycode < 193) || // ;=,-./` (in order)
    (keycode > 218 && keycode < 223); // [\]' (in order)
  return valid;
}

/**
 * Gives a string representation of binary data.
 *
 * @param {ArrayBuffer} buffer
 * @returns {string} the string representation.
 */
export function hexDump(buffer: ArrayBuffer): string {
  const dataView = new DataView(buffer, 0);
  debug('buffer length', buffer.byteLength);
  let result = '';
  let line = '';
  for (let i = 0; i < buffer.byteLength; i++) {
    if (i % 16 === 0) {
      line = '';
      const address = '0x' + i.toString(10).padStart(8, '0') + ':';
      result += address;
    }
    const n = dataView.getUint8(i);
    result += n.toString(16).padStart(2, '0') + ' ';
    let c = '.';
    if (isPrintable(n)) {
      c = String.fromCharCode(n);
    }
    line += c;
    if (i % 16 === 7) {
      result += ' ';
    }
    if (i === buffer.byteLength - 1) {
      const spaces = '   ';
      for (let j = 0; j < 15 - (i % 16); j++) {
        result += spaces;
      }
    }
    if (i % 16 === 15 || i === buffer.byteLength - 1) {
      result += ': ' + line + '\n';
      continue;
    }
  }
  return result;
}

export function toHex(buffer: ArrayBuffer): string {
  const dataView = new DataView(buffer, 0);
  debug('buffer length', buffer.byteLength);
  let result = '';
  for (let i = 0; i < buffer.byteLength; i++) {
    const n = dataView.getUint8(i);
    result += n.toString(16).padStart(2, '0');
  }
  return result;
}

export function getMessageType(token: string): MessageType {
  const buffer = decode(token);
  const str = toHex(buffer);
  // manage NTLM
  if (str.includes('4e544c4d53535000' + '01')) {
    return 'NTLM_NEGOTIATE_01';
  }
  if (str.includes('4e544c4d53535000' + '02')) {
    return 'NTLM_CHALLENGE_02';
  }
  if (str.includes('4e544c4d53535000' + '03')) {
    return 'NTLM_AUTHENTICATE_03';
  }
  // manage Kerberos:
  if (token.startsWith('YII')) {
    return 'Kerberos_1';
  }
  return 'Kerberos_N';
}