Python - SSL Issue with Oauth2

Question

I seem to be having an issue with SSL whenever trying to use oAuth2 in Python. I've spent most of the afternoon attempting to debug it but can't seem to figure it out.

Here's my Python Script (Nice and simple):

import oauth2.oauth2 as oauth
import urlparse
import time

## If you're actually processing requests, you'll want this
# import simplejson


### GET A REQUEST TOKEN ###

consumer = oauth.Consumer(key="***KEYHERE***", secret="***KEYSECRETHERE***")

request_token_url = 'https://api.instagram.com/oauth/access_token'

client = oauth.Client(consumer)
resp, content = client.request(request_token_url, "GET")

request_token = dict(urlparse.parse_qsl(content))


token = oauth.Token(request_token['oauth_token'], request_token['oauth_token_secret'])

And these error from the Python Interpreter:

Traceback (most recent call last):
  File "E:\Projects\oAuth2Test\test.py", line 16, in <module>
    resp, content = client.request(request_token_url, "GET")
  File "E:\Projects\oAuth2Test\oauth2\oauth2.py", line 682, in request
    connection_type=connection_type)
  File "E:\Projects\oAuth2Test\httplib2\httplib2.py", line 1445, in request
    (response, content) = self._request(conn, authority, uri, request_uri, method, body, headers, redirections, cachekey)
  File "E:\Projects\oAuth2Test\httplib2\httplib2.py", line 1197, in _request
    (response, content) = self._conn_request(conn, request_uri, method, body, headers)
  File "E:\Projects\oAuth2Test\httplib2\httplib2.py", line 1133, in _conn_request
    conn.connect()
  File "E:\Projects\oAuth2Test\httplib2\httplib2.py", line 914, in connect
    raise SSLHandshakeError(e)
SSLHandshakeError: [Errno 1] _ssl.c:503: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

Now, just so it's known, I have my cacerts.txt that came with httplib2 in the proper place and it is found, yet I still have this problem. Any help is appreciated, thanks!

Answer 1

cacerts.txt contains too few CAs. If you replace it with cacert.pem then there is no ssl error. Here's a test script:

#!/usr/bin/env python3
import http.client
import ssl

####context = ssl.create_default_context(cafile='cacerts.txt') # ssl.SSLError
####context = ssl.create_default_context(cafile='cacert.pem')  # works   
context = ssl.create_default_context()  # works as is on the recent versions
#NOTE: ssl.CERT_REQUIRED is set for the default Purpose.SERVER_AUTH

h = http.client.HTTPSConnection('api.instagram.com', 443, context=context)
h.request('POST', '/oauth/access_token')
resp = h.getresponse()
print(resp.status, resp.reason) # produce expected 400 http error
print(resp.headers)
print(resp.read())

As the example demonstrates, the default CA list might be enough on the recent software versions.