litecraft-yggdrasil/lib/utils.js

Mojang authentication (Yggdrasil) client

var version = require('../package.json').version
var phin = require('phin')

var headers = {
  'User-Agent': 'litecraft-yggdrasil/' + version,
  'Content-Type': 'application/json'
}

var utils = {}

utils.phin = phin

/**
 * Get JSON from POST request
 */
utils.call = function (host, path, data, cb) {
  phin({
    method: 'POST',
    url: host + '/' + path,
    data: data,
    headers: headers
  }, function (err, resp) {
    if (resp.body.length === 0) {
      cb(null, '')
      return
    }
    try {
      var body = JSON.parse(resp.body)
    } catch (caughtErr) {
      err = caughtErr
    }
    if (body && body.error) {
      cb(new Error(body.errorMessage))
    } else {
      cb(err, body)
    }
  })
}

/**
 * Generic POST request
 */
utils.post = function (host, path, data, cb) {
  phin({
    method: 'POST',
    url: host + '/' + path,
    data: data,
    headers: headers
  }, function (err, resp) {
    cb(err, resp)
  })
}

/**
 * Java's annoying hashing method.
 * All credit to andrewrk
 * https://gist.github.com/andrewrk/4425843
 */
function performTwosCompliment (buffer) {
  var carry = true
  var i, newByte, value
  for (i = buffer.length - 1; i >= 0; --i) {
    value = buffer.readUInt8(i)
    newByte = ~value & 0xff
    if (carry) {
      carry = newByte === 0xff
      buffer.writeUInt8(carry ? 0 : (newByte + 1), i)
    } else {
      buffer.writeUInt8(newByte, i)
    }
  }
}

/**
 * Java's stupid hashing method
 * @param  {Buffer|String} hash     The hash data to stupidify
 * @param  {String} encoding Optional, passed to Buffer() if hash is a string
 * @return {String}          Stupidified hash
 */
utils.mcHexDigest = function mcHexDigest (hash, encoding) {
  if (!(hash instanceof Buffer)) {
    hash = Buffer.from(hash, encoding)
  }
  // check for negative hashes
  var negative = hash.readInt8(0) < 0
  if (negative) performTwosCompliment(hash)
  var digest = hash.toString('hex')
  // trim leading zeroes
  digest = digest.replace(/^0+/g, '')
  if (negative) digest = '-' + digest
  return digest
}

module.exports = utils