[New-bugs-announce] [issue28170] SystemError: <built-in method peer_certificate of _ssl._SSLSocket object at 0x7f98ac154858> returned NULL without setting an error

[Matt Wright]

New submission from Matt Wright:

I'm experiencing a strange error when connecting to a web server with a self signed certificate. I've added the Root and Intermediate certs to the system CA bundle, and can `curl` against the server without any errors or using the `k` flag. But Python (via requests) raises an error that I can't seem to figure out at all with the `peer_certificate` method. Below you'll find the specific error:

```
import requests
requests.get('https://localhost:9200/_cluster/health', verify='/etc/ssl/certs/ca-certificates.crt')
Traceback (most recent call last):
  File "test.py", line 2, in <module>
    requests.get('https://localhost:9200/_cluster/health', verify='/etc/ssl/certs/ca-certificates.crt')
  File "/usr/lib/python3/dist-packages/requests/api.py", line 67, in get
    return request('get', url, params=params, **kwargs)
  File "/usr/lib/python3/dist-packages/requests/api.py", line 53, in request
    return session.request(method=method, url=url, **kwargs)
  File "/usr/lib/python3/dist-packages/requests/sessions.py", line 468, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/lib/python3/dist-packages/requests/sessions.py", line 576, in send
    r = adapter.send(request, **kwargs)
  File "/usr/lib/python3/dist-packages/requests/adapters.py", line 376, in send
    timeout=timeout
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 560, in urlopen
    body=body, headers=headers)
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 346, in _make_request
    self._validate_conn(conn)
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 787, in _validate_conn
    conn.connect()
  File "/usr/lib/python3/dist-packages/urllib3/connection.py", line 259, in connect
    cert = self.sock.getpeercert()
  File "/usr/lib/python3.5/ssl.py", line 818, in getpeercert
    return self._sslobj.getpeercert(binary_form)
  File "/usr/lib/python3.5/ssl.py", line 595, in getpeercert
    return self._sslobj.peer_certificate(binary_form)
SystemError: <built-in method peer_certificate of _ssl._SSLSocket object at 0x7f98ac154858> returned NULL without setting an error
```

----------
assignee: christian.heimes
components: SSL
messages: 276567
nosy: Matt Wright, christian.heimes
priority: normal
severity: normal
status: open
title: SystemError: <built-in method peer_certificate of _ssl._SSLSocket object at 0x7f98ac154858> returned NULL without setting an error
type: behavior
versions: Python 3.5

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue28170>
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