SSLV3_ALERT_HANDSHAKE_FAILURE after upgrade from 2.31.0 to 2.32.2

After upgrading to requests 2.32.* our custom SSL adapter doesn't seem to working anymore. This is how it looks like

```
class CustomSSLAdapter(HTTPAdapter):
    def __init__(self):
        self.context = ssl.create_default_context()

        certfile = ...
        keyfile = ...
        password = ...
        self.context.load_cert_chain(certfile=certfile, keyfile=keyfile, password=password)
        
        super().__init__()

    def init_poolmanager(self, *args, **kwargs):
        kwargs['ssl_context'] = self.context
        return super().init_poolmanager(*args, **kwargs)
```

We have tried to mount this only for the target url but also for "http://". The code was working find with version 2.31.0.

## Expected Result

The adapter should still work.

## Actual Result

We got the following error:

```
SSLError: HTTPSConnectionPool(host=..., port=543): Max retries exceeded with url: ... (Caused by SSLError(SSLError(1, '[SSL: SSLV3_ALERT_HANDSHAKE_FAILURE] sslv3 alert handshake failure (_ssl.c:1007)')))
```


This is running on databricks using python 3.10.12. 

@nateprewitt this is a different side-effect of #6655. I think to enable this particular use case we need to expose a way for sub-classes to muck with the pool kwargs, something like


```py
class HTTPAdapter(BaseAdapter):
    def build_pool_kwargs(self, request, verify, cert=None):
        return _urllib3_request_context(request, verify, cert)
```

That way a subclass like this could do something like:


```py
class CustomSSLAdapter(HTTPAdapter):
    def build_pool_kwargs(self, request, verify, cert=None):
        params, kwargs = super().build_pool_kwargs(request, verify, cert)
        params["ssl_context"] = self.context
```

Thoughts? I'm not particularly fond of this but it seems like the least intrusive way to preserve the fix for the CVE while giving people the ability to use custom SSLContexts the way they already were

We have a different error, but probably the same issue. We inject a `ssl_context` with a custom cipher selection. If there is a more "correct" way to do this I can also update our code, but a fix in the library would be appreciated.

Anyway, thanks for the quick response.

You will need to fix your code but right now it's not easily doable

when do you expect releasing v2.32.3 which is suggested at #6716?

@DanSIntel See the conversation in the MR: https://github.com/psf/requests/pull/6716#pullrequestreview-2072332359

On requests 2.32.x with truststore we are seeing a maximum recursion error with verify=True on windows Jupyter labs and jupyter notebook environments.



```
import requests
with requests.Session() as session:
   
     print(session.get("https://www.arcgis.com/sharing/rest/portals/self?f=json").text)
```

@achapkowski I don't see trust store being used there or any kind of traceback 

I also can't reproduce your claim @achapkowski but I don't have windows available:

```py
>>> import truststore; truststore.inject_into_ssl()
>>> import requests
>>> requests.get('https://google.com')
<Response [200]>
>>> requests.get('https://www.arcgis.com/sharing/rest/portals/self?f=json')
<Response [200]>
```

![image](https://github.com/psf/requests/assets/5131271/145d1b1c-7c83-4fe4-ad84-84a807c00a0b)


It recursively occurs here. 

full stack attached:

[full-stack-error.txt](https://github.com/psf/requests/files/15416590/full-stack-error.txt)


Dug in a bit more:

```
import requests
print(requests.get("https://www.arcgis.com/sharing/rest/portals/self?f=json").text)
with requests.Session() as session:
    print(session.get("https://www.arcgis.com/sharing/rest/portals/self?f=json").text)
```
The above works on windows

Below will fails on windows.  Works on Mac/Linux
```
import truststore
truststore.inject_into_ssl()
with requests.Session() as session:
    print(session.get("https://www.arcgis.com/sharing/rest/portals/self?f=json").text)
```



I posted a response to the recursion issue in https://github.com/psf/requests/pull/6716#issuecomment-2127152349. This is already known behavior that was reported to be broken in arcgis previously due to misuse of truststore (https://github.com/Esri/arcgis-python-api/issues/1698). It will need to be fixed there. That's unrelated to the topic of this issue.

For the minimal repro, you're producing this because your repro is also misusing truststore in the same way as `arcgis`. `truststore` MUST be imported before any networking code for either urllib3 or Requests. `inject_into_ssl()` is not an intended entry point for any library or package code. You'll find a [large warning](https://github.com/sethmlarson/truststore/?tab=readme-ov-file#user-guide) at the top of the user guide directing users to avoid this.

You can swap the order of your imports and the above repro works fine on Windows:
```
# Must be done first
import truststore
truststore.inject_into_ssl()

import requests
with requests.Session() as session:
    print(session.get("https://www.arcgis.com/sharing/rest/portals/self?f=json").text)
```

I had a similar issue. Try setting the `REQUESTS_CA_BUNDLE=` environment variable if possible to point to your CA bundle

We used pip-system-certs to trust the os bundle which has custom CAs in. I dont fully understand why but since 2.32.0 we get what I think is the same issue. Someone has raised an issue over at gitab https://gitlab.com/alelec/pip-system-certs/-/issues/27

https://github.com/psf/requests/pull/6721 is staged for release on Tuesday. We're going to hold releasing over the weekend to avoid any unnecessary pain for ops teams and will release after the holiday in the US on Monday. You can follow along for the merge of that PR to track the release time.

@nateprewitt 

For the adapter issue with 2.32.x do developers need to modify their logic? Is that documented anywhere if so?

Also thank you for the quick fix! 

@achapkowski If you're using the `init_poolmanager` setup now like what's linked in the example, you shouldn't need to make any additional changes. 2.32.3 should work the same as 2.31.0 and earlier. If you want to do anything more than what's described in the first post of this issue, the new `build_connection_pool_key_attributes` will be the escape hatch to do any additional customization.

Alright, 2.32.3 is out. Thanks everyone for your patience, please let us know if you're still hitting this failure case after upgrading.

> Alright, 2.32.3 is out. Thanks everyone for your patience, please let us know if you're still hitting this failure case after upgrading.

With 2.32.0-2.32.2 I've been seeing the same issue when using requests_pkcs12; now with 2.32.3, the issue did unfortunately not disappear but rather move to `HTTPSConnectionPool(host='some.system', port=443): Max retries exceeded with url: /foo/bar (Caused by SSLError(SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1006)')))`.

I've opened an issue with requests_pkcs12, but since you specifically asked to point out problems where things do not behave like in 2.31.0...

We also use requests_pkcs12 and I can confirm that 2.32.3 doesn't work with it. Stack trace I saw:

`
Traceback (most recent call last):
  File "/workspace/.venv/lib/python3.11/site-packages/urllib3/connectionpool.py", line 715, in urlopen
    httplib_response = self._make_request(
                       ^^^^^^^^^^^^^^^^^^^
  File "/workspace/.venv/lib/python3.11/site-packages/urllib3/connectionpool.py", line 404, in _make_request
    self._validate_conn(conn)
  File "/workspace/.venv/lib/python3.11/site-packages/urllib3/connectionpool.py", line 1058, in _validate_conn
    conn.connect()
  File "/workspace/.venv/lib/python3.11/site-packages/urllib3/connection.py", line 419, in connect
    self.sock = ssl_wrap_socket(
                ^^^^^^^^^^^^^^^^
  File "/workspace/.venv/lib/python3.11/site-packages/urllib3/util/ssl_.py", line 449, in ssl_wrap_socket
    ssl_sock = _ssl_wrap_socket_impl(
               ^^^^^^^^^^^^^^^^^^^^^^
  File "/workspace/.venv/lib/python3.11/site-packages/urllib3/util/ssl_.py", line 493, in _ssl_wrap_socket_impl
    return ssl_context.wrap_socket(sock, server_hostname=server_hostname)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/ssl.py", line 517, in wrap_socket
    return self.sslsocket_class._create(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/ssl.py", line 1108, in _create
    self.do_handshake()
  File "/usr/lib/python3.11/ssl.py", line 1379, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1006)
`