Twisted 17.1.0 tls fails on python 2.7.5 due missing OP_NO_TLSv1_1

	@noc0lour reported
Trac ID	trac#9121
Type	defect
Created	2017-04-25 17:36:24Z

I'm trying to run a twisted application on a CentOS7 container with necessary deps installed.

All deps are istalled from the official CentOS7 repo

• OpenSSL version: 1.0.1e
• Python version: 2.7.5

If I downgrade to Twisted 16.0.0 everything works fine.

[buildbot@86134cdfec09 buildbot]$ twistd -ny buildbot.tac 
Unhandled Error
Traceback (most recent call last):
  File "/usr/lib64/python2.7/site-packages/twisted/application/app.py", line 662, in run
    runApp(config)
  File "/usr/lib64/python2.7/site-packages/twisted/scripts/twistd.py", line 25, in runApp
    _SomeApplicationRunner(config).run()
  File "/usr/lib64/python2.7/site-packages/twisted/application/app.py", line 380, in run
    self.application = self.createOrGetApplication()
  File "/usr/lib64/python2.7/site-packages/twisted/application/app.py", line 445, in createOrGetApplication
    application = getApplication(self.config, passphrase)
--- <exception caught here> ---
  File "/usr/lib64/python2.7/site-packages/twisted/application/app.py", line 456, in getApplication
    application = service.loadApplication(filename, style, passphrase)
  File "/usr/lib64/python2.7/site-packages/twisted/application/service.py", line 413, in loadApplication
    passphrase)
  File "/usr/lib64/python2.7/site-packages/twisted/persisted/sob.py", line 223, in loadValueFromFile
    eval(codeObj, d, d)
  File "buildbot.tac", line 9, in <module>
    from buildbot_worker.bot import Worker
  File "/usr/lib/python2.7/site-packages/buildbot_worker/bot.py", line 19, in <module>
    from buildbot_worker.null import LocalWorker
  File "/usr/lib/python2.7/site-packages/buildbot_worker/null.py", line 21, in <module>
    from buildbot_worker.base import WorkerBase
  File "/usr/lib/python2.7/site-packages/buildbot_worker/base.py", line 26, in <module>
    from twisted.internet import reactor
  File "/usr/lib64/python2.7/site-packages/twisted/internet/reactor.py", line 38, in <module>
    from twisted.internet import default
  File "/usr/lib64/python2.7/site-packages/twisted/internet/default.py", line 56, in <module>
    install = _getInstallFunction(platform)
  File "/usr/lib64/python2.7/site-packages/twisted/internet/default.py", line 44, in _getInstallFunction
    from twisted.internet.epollreactor import install
  File "/usr/lib64/python2.7/site-packages/twisted/internet/epollreactor.py", line 24, in <module>
    from twisted.internet import posixbase
  File "/usr/lib64/python2.7/site-packages/twisted/internet/posixbase.py", line 18, in <module>
    from twisted.internet import error, udp, tcp
  File "/usr/lib64/python2.7/site-packages/twisted/internet/tcp.py", line 28, in <module>
    from twisted.internet._newtls import (
  File "/usr/lib64/python2.7/site-packages/twisted/internet/_newtls.py", line 21, in <module>
    from twisted.protocols.tls import TLSMemoryBIOFactory, TLSMemoryBIOProtocol
  File "/usr/lib64/python2.7/site-packages/twisted/protocols/tls.py", line 63, in <module>
    from twisted.internet._sslverify import _setAcceptableProtocols
  File "/usr/lib64/python2.7/site-packages/twisted/internet/_sslverify.py", line 38, in <module>
    TLSVersion.TLSv1_1: SSL.OP_NO_TLSv1_1,
exceptions.AttributeError: 'module' object has no attribute 'OP_NO_TLSv1_1'


Failed to load application: 'module' object has no attribute 'OP_NO_TLSv1_1'

trac-id__9121 9121
type__defect defect
reporter__noc0lour noc0lour
priority__normal normal
milestone__None None
branch__ 
branch_author__ 
status__new new
resolution__None None
component__core core
keywords__None None
time__1493141784860374 1493141784860374
changetime__1495562062302269 1495562062302269
version__None None
owner__None None

Start in twisted/internet/_sslverify.py at the TLSVersion mapping that references SSL.OP_NO_TLSv1_1, and reproduce the import failure with Python 2.7.5 and OpenSSL 1.0.1e. Trace the TLS setup path from twisted/internet/tcp.py and confirm that Twisted starts and configures TLS without raising the missing-attribute error on the affected environment.