permessage-deflate/lib/common.js

Per-message DEFLATE compression extension for WebSocket connections

'use strict';

var Buffer = require('safe-buffer').Buffer;

var common = {
  VALID_PARAMS: [
    'server_no_context_takeover',
    'client_no_context_takeover',
    'server_max_window_bits',
    'client_max_window_bits'
  ],

  MIN_WINDOW_BITS:   9,
  MAX_WINDOW_BITS:   15,
  VALID_WINDOW_BITS: [8, 9, 10, 11, 12, 13, 14, 15],

  fetch: function(options, key, _default) {
    if (options.hasOwnProperty(key))
      return options[key];
    else
      return _default;
  },

  validateOptions: function(options, validKeys) {
    for (var key in options) {
      if (validKeys.indexOf(key) < 0)
        throw new Error('Unrecognized option: ' + key);
    }
  },

  validParams: function(params) {
    var keys = Object.keys(params), i = keys.length;
    while (i--) {
      if (this.VALID_PARAMS.indexOf(keys[i]) < 0) return false;
      if (params[keys[i]] instanceof Array) return false;
    }
    if (params.hasOwnProperty('server_no_context_takeover')) {
      if (params.server_no_context_takeover !== true) return false;
    }
    if (params.hasOwnProperty('client_no_context_takeover')) {
      if (params.client_no_context_takeover !== true) return false;
    }
    if (params.hasOwnProperty('server_max_window_bits')) {
      if (this.VALID_WINDOW_BITS.indexOf(params.server_max_window_bits) < 0) return false;
    }
    return true;
  }
};

module.exports = common;