GreenSSLContext does not handle the SSLContext minimum_version property and results in RecursionErrors #726
Description
This is similar to #371
Running httpx==0.19.0 with eventlet==0.30.2 results in RecursionError exceptions when httpx tries to set the minimum TLS version in the SSLContext object (encode/httpx#1873 (comment))
For example, running the following with httpx==0.19.0:
from eventlet import monkey_patch
monkey_patch(socket=False)
from httpx import Client
x = Client()results in:
Traceback (most recent call last):
File "eventletfoo.py", line 5, in <module>
x = Client()
File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_client.py", line 648, in __init__
self._transport = self._init_transport(
File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_client.py", line 696, in _init_transport
return HTTPTransport(
File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_transports/default.py", line 129, in __init__
ssl_context = create_ssl_context(verify=verify, cert=cert, trust_env=trust_env)
File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_config.py", line 50, in create_ssl_context
return SSLConfig(
File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_config.py", line 74, in __init__
self.ssl_context = self.load_ssl_context()
File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_config.py", line 86, in load_ssl_context
return self.load_ssl_context_verify()
File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_config.py", line 123, in load_ssl_context_verify
context = self._create_default_ssl_context()
File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_config.py", line 158, in _create_default_ssl_context
set_minimum_tls_version_1_2(context)
File "/home/bobh/PyCharmProjects/python-backend/.tox/dev/lib/python3.8/site-packages/httpx/_compat.py", line 37, in set_minimum_tls_version_1_2
context.minimum_version = ssl.TLSVersion.TLSv1_2
File "/usr/lib/python3.8/ssl.py", line 586, in minimum_version
super(SSLContext, SSLContext).minimum_version.__set__(self, value)
File "/usr/lib/python3.8/ssl.py", line 586, in minimum_version
super(SSLContext, SSLContext).minimum_version.__set__(self, value)
File "/usr/lib/python3.8/ssl.py", line 586, in minimum_version
super(SSLContext, SSLContext).minimum_version.__set__(self, value)
[Previous line repeated 490 more times]
File "/usr/lib/python3.8/ssl.py", line 584, in minimum_version
if value == TLSVersion.SSLv3:
RecursionError: maximum recursion depth exceeded while calling a Python object
Running the same code with httpx==0.18.2 does not have the problem because they don't try to set the minimum TLS version.
The "easy" solution is for the GreenSSLContext object to handle the SSLContext minimum_version property the same way it handles the other properties. However there are additional SSLContext properties that are also not handled by GreenSSLContext, such as maximum_version, _msg_callback and hostname_checks_common_name. The maximum_version property is similar to minimum_version, but the others are more complicated so a generic solution does not appear to be trivial.
I'll push a PR for these two properties for now.