OAuth2Client

Presentation

OAuth2Client is a simple python client library for OAuth2. It is based on the requests

warning:	Starting version 1.2.0, versions older that python 3.6.0 will not be supported anymore. This late version was released by the end 2016.

For those that are still using python 2.7, it won't be supported by the end of 2020 and all library shall stop supporting it.

Login process

For now it can handle two token process:

Authorization code
User Credentials
Client Credentials

Authorization code

Since authorization code process needs the user to accept the access to its data by the application, the library starts locally a http server. You may put the host part of the redirect_uri parameter in your hosts file pointing to your loop-back address. The server waits a GET requests with the code as a query parameter.

Getting a couple of access token may be done like this:

scopes = ['scope_1', 'scope_2']

service_information = ServiceInformation('https://authorization-server/oauth/authorize',
                                         'https://token-server/oauth/token',
                                         'client_id',
                                         'client_secret',
                                          scopes)
manager = CredentialManager(service_information,
                            proxies=dict(http='http://localhost:3128', https='http://localhost:3128'))
redirect_uri = 'http://somewhere.io:8080/oauth/code'

# Builds the authorization url and starts the local server according to the redirect_uri parameter
url = manager.init_authorize_code_process(redirect_uri, 'state_test')
_logger.info('Open this url in your browser\n%s', url)

code = manager.wait_and_terminate_authorize_code_process()
# From this point the http server is opened on 8080 port and wait to receive a single GET request
# All you need to do is open the url and the process will go on
# (as long you put the host part of your redirect uri in your host file)
# when the server gets the request with the code (or error) in its query parameters
_logger.debug('Code got = %s', code)
manager.init_with_authorize_code(redirect_uri, code)
_logger.debug('Access got = %s', manager._access_token)
# Here access and refresh token may be used with self.refresh_token

Authorization code with Proof Key for Code Exchange (PKCE)

In case you can generate a couple of code verifier and code challenge as follows:

import base64
import hashlib
import logging
import secrets
from typing import Tuple

def generate_sha256_pkce(length: int) -> Tuple[str, str]:
    if not (43 <= length <= 128):
        raise Exception("Invalid length: " % str(length))
    verifier = secrets.token_urlsafe(length)
    encoded = base64.urlsafe_b64encode(hashlib.sha256(verifier.encode('ascii')).digest())
    challenge = encoded.decode('ascii')[:-1]
    return verifier, challenge

Then you can init authorization code workflow as follows

code_verifier, code_challenge = generate_sha256_pkce(64)
url = manager.init_authorize_code_process(redirect_uri, 'state_test',
                                          code_challenge=code_challenge,
                                          code_challenge_method="S256")

or either generate the url

url = manager.generate_authorize_url(redirect_uri, 'state_test',
                                     code_challenge=code_challenge,
                                     code_challenge_method="S256")

And once you obtains the code exchange it as follows

manager.init_with_authorize_code(redirect_uri, code, code_verifier=code_verifier)

User credentials

Getting a couple of access and refresh token is much easier:

scopes = ['scope_1', 'scope_2']

service_information = ServiceInformation('https://authorization-server/oauth/authorize',
                                         'https://token-server/oauth/token',
                                         'client_id',
                                         'client_secret',
                                          scopes)
manager = CredentialManager(service_information,
                            proxies=dict(http='http://localhost:3128', https='http://localhost:3128'))
manager.init_with_user_credentials('login', 'password')
_logger.debug('Access got = %s', manager._access_token)
# Here access and refresh token may be used

Client credentials

You can also get a token with client credentials process

manager = CredentialManager(service_information,
                            proxies=dict(http='http://localhost:3128', https='http://localhost:3128'))
manager.init_with_client_credentials()
# here application admin operation may be called

Refresh token

Provided that you kept a previous refresh_token, you can initiate your credential manager with it:

manager = CredentialManager(service_information,
                            proxies=dict(http='http://localhost:3128', https='http://localhost:3128'))
manager.init_with_token('my saved refreshed token')

Token expiration

CredentialManager class handle token expiration by calling the CredentialManager._is_token_expired static method. This implementation is not accurate for all OAuth server implementation. You'd better extend CredentialManager class and override _is_token_expired method.

Read other fields from token response

CredentialManager can be subclassed to handle other token response fields such as id_token in OpenId protocol.

class OpenIdCredentialManager(CredentialManager):
    def __init__(self, service_information, proxies=None):
        super(OpenIdCredentialManager, self).__init__(service_information, proxies)
        self.id_token = None

    def _process_token_response(self,  token_response, refresh_token_mandatory):
        id_token = token_response.get('id_token')
        OpenIdCredentialManager._check_id(id_token)
        super(OpenIdCredentialManager, self)._process_token_response(token_response, refresh_token_mandatory)
        self.id_token = id_token

    @staticmethod
    def _check_id(id_token):
        # check that open id token is valid
        pass

antechrestos/OAuth2Client