Twisted Core 17.1.0 (2017-02-04)
================================

Features
--------
- Added a new interface,
  twisted.internet.interfaces.IHostnameResolver, which is an
  improvement to twisted.internet.interfaces.IResolverSimple that
  supports resolving multiple addresses as well as resolving IPv6
  addresses.  This is a native, asynchronous, Twisted analogue to
  getaddrinfo. (bug-4362)
- twisted.web.client.Agent now uses HostnameEndpoint internally; as a
  consequence, it now supports IPv6, as well as making connections
  faster and more reliably to hosts that have more than one DNS name.
  (bug-6712)
- twisted.internet.ssl.CertificateOptions now has the new constructor
  argument 'raiseMinimumTo', allowing you to increase the minimum TLS
  version to this version or Twisted's default, whichever is higher.
  The additional new constructor arguments 'lowerMaximumSecurityTo'
  and 'insecurelyLowerMinimumTo' allow finer grained control over
  negotiated versions that don't honour Twisted's defaults, for
  working around broken peers, at the cost of reducing the security
  of the TLS it will negotiate. (bug-6800)
- twisted.internet.ssl.CertificateOptions now sets the OpenSSL
  context's mode to MODE_RELEASE_BUFFERS, which will free the
  read/write buffers on idle TLS connections to save memory. (bug-8247)
- trial --help-reactors will only list reactors which can be
  imported.  (bug-8745)
- twisted.internet.endpoints.HostnameEndpoint now uses the passed
  reactor's implementation of
  twisted.internet.interfaces.IReactorPluggableResolver to resolve
  hostnames rather than its own deferToThread/getaddrinfo wrapper;
  this makes its hostname resolution pluggable via a public API.
  (bug-8922)
- twisted.internet.reactor.spawnProcess now does not emit a
  deprecation warning on Unicode arguments. It will encode Unicode
  arguments down to bytes using the filesystem encoding on UNIX and
  Python 2 on Windows, and pass Unicode through unchanged on Python 3
  on Windows. (bug-8941)
- twisted.trial._dist.test.test_distreporter now works on Python 3.
  (bug-8943)

Bugfixes
--------
- trial --help-reactors will now display iocp and win32er reactors
  with Python 3. (bug-8745)
- twisted.logger._flatten.flattenEvent now handles log_format being
  None instead of assuming the value is always a string. (bug-8860)
- twisted.protocol.ftp is now Python 3 compatible (bug-8865)
- twisted.names.client.Resolver can now resolve names with IPv6 DNS
  servers. (bug-8877)
- twisted.application.internet.ClientService now waits for existing
  connections to disconnect before trying to connect again when
  restarting. (bug-8899)
- twisted.internet.unix.Server.doRead and
  twisted.internet.unix.Client.doRead no longer fail if recvmsg's
  ancilliary data contains more than one file descriptor. (bug-8911)
- twist on Python 3 now correctly prints the help text when given no
  plugin to run. (bug-8918)
- twisted.python.sendmsg.sendmsg no longer segfaults on Linux +
  Python 2. (bug-8969)
- IHandshakeListener providers connected via SSL4ClientEndpoint will
  now have their handshakeCompleted methods called. (bug-8973)
- The twist script now respects the --reactor option. (bug-8983)
- Fix crash when using SynchronousTestCase with Warning object which
  does not store a string as its first argument (like
  libmysqlclient). (bug-9005)
- twisted.python.compat.execfile() does not open files with the
  deprecated 'U' flag on Python 3. (bug-9012)

Deprecations and Removals
-------------------------
- twisted.internet.ssl.CertificateOption's 'method' constructor
  argument is now deprecated, in favour of the new 'raiseMinimumTo',
  'lowerMaximumSecurityTo', and 'insecurelyLowerMinimumTo' arguments.
  (bug-6800)
- twisted.protocols.telnet (not to be confused with the supported
  twisted.conch.telnet), deprecated since Twisted 2.5, has been
  removed. (bug-8925)
- twisted.application.strports.parse, as well as the deprecated
  default arguments in strports.service/listen, deprecated since
  Twisted 10.2, has been removed. (bug-8926)
- twisted.web.client.getPage and twisted.web.client.downloadPage have
  been deprecated in favour of https://pypi.org/project/treq and
  twisted.web.client.Agent. (bug-8960)
- twisted.internet.defer.timeout is deprecated in favor of
  twisted.internet.defer.Deferred.addTimeout (bug-8971)

(adam)