========================= Djforge Redis Multitokens

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Compatible with: Python: 2.7, 3.4, 3.5, 3.6 Django: 1.10, 1.11 DRF: 3.6

What Does djforge-redis-multitokens Do?

The djforge-redis-multitokens is a plugin for Django Rest Framework that allows you to create multiple tokens for each user(one per device or browser) and store them in Redis. Here's why you may want to use this plugin:

• Your users have multiple devices and a log out from one device(or browser) should not log the user out on other devices(or browsers)
• Token retrieval, validation, and updates should be fast. This plugin uses Redis, can't touch this!
• Security is important to you. This plugin encrypts users' tokens so even if an attacker gets access to all your tokens they would not be able to do anything with them.

Note: device in this document means a physical one or a browser.

How to Install

First, download the package and install it using pip:

.. code-block:: bash

pip install git+https://github.com/ToReforge/djforge-redis-multitokens

Or simple:

.. code-block:: bash

pip install djforge-redis-multitokens

Then, you'll need Django, Django REST Framework, and Redis. Finally, your Django app needs to be able to talk to Redis, so you'll need a library like django-redis or django-redis-cache. Follow the instructions here(http://django-redis-cache.readthedocs.io/en/latest/intro_quick_start.html) to setup Django with Redis.

How to Use It

Create a Redis DB For Tokens

Once you're done with the installation step, make a Redis db for your tokens in your Django settings file:

.. code-block:: python

CACHES = { # other Redis db definitions above

    # tokens db definition
    'tokens': {
        'BACKEND': 'redis_cache.RedisCache',
        'LOCATION': 'localhost:6379',
        'OPTIONS': {
            'DB': 2,
        },
        'TIMEOUT': None,
    }
}

Notes:

• In the above definition, we're setting "tokens" as the name for the Redis db that will contain tokens. You can change this name, more on that later.
• TIMEOUT is used to expire tokens. TIMEOUT: 10000 means that new tokens will be valid for 10000 before they expire and are removed from Redis.

Custom Settings

.. code-block:: python

DJFORGE_REDIS_MULTITOKENS = {
    'REDIS_DB_NAME': 'custom_redis_db_name_for_tokens',
    'RESET_TOKEN_TTL_ON_USER_LOG_IN': True,
    'OVERWRITE_NONE_TTL': True,
}

Put the above in your Django settings module to customize the behavior of djforge-redis-multitokens:

• REDIS_DB_NAME: set this to the same name you defined for your Redis db("tokens" in the above defnition).
• RESET_TOKEN_TTL_ON_USER_LOG_IN extends the life of tokens by TIMEOUT seconds(set in settings.CACHES).
• OVERWRITE_NONE_TTL will overwrite the previous ttl of None (None means Redis will never expire your token) set on a token. Set this to False if you don't want your immortal tokens to become mortal.
• In other words, if you set OVERWRITE_NONE_TTL to False, the ttl of tokens with ttl None will not change. They will never expire.

Setup Token Authentication

There's complicated logic involved in token authentication, but Django REST framework(DRF) comes with a "pluggable" authentication module that supports token authentication so that djforge-redis-multitokens can change where tokens are stored. We want our tokens to be stored in Redis, so we have to change the default authentication class:

.. code-block:: python

REST_FRAMEWORK = {
    'DEFAULT_AUTHENTICATION_CLASSES': (
        ' djforge_redis_multitokens.tokens_auth.CachedTokenAuthentication',
    ),
    # your other DRF configurations goes below
}

Note: With this setting, we ask DFR to use CachedTokenAuthentication to check if users have the right token whenever they log in. CachedTokenAuthentication is a subclass of DRF's TokenAuthentication which overrides how tokens are fetched from storage.

Create New Tokens

Usually, you want to create a new token whenever a user logs in from a new device:

.. code-block:: python

from  djforge_redis_multitokens.tokens_auth import MultiToken

# create new token in your login logic
def login_handler(request):
    token, _ = MultiToken.create_token(request.user) # request object in DRF has a user attribute
    # _ variable is a boolean that denotes whether this is the first token created for this user

Notes:

• Before your login handler function is invoked, DRF checks to see if your user has a valid token. So, the above function is not invoked for users who have a valid token.
• MultiToken.create_token takes an instance of settings.AUTH_USER_MODEL which Django calls the User model.
• The _ variable, if it is False, tells you that the user is logged in on another device(or browser).
• The token object has two attributes: key and user. DRF expects custom tokens to have these attributes. key is the string user receives as their token and user is an instance of the settings.AUTH_USER_MODEL model.

Expiring Tokens

When a user logs out(usually by pressing the "log out" button on your user interface), you usually expire the token associated with that device:

.. code-block:: python

from  djforge_redis_multitokens.tokens_auth import MultiToken

def logout_handler(request):
    # DFR request object has an `auth` attribute which is of type MultiToken
    MultiToken.expire_token(request.auth)

Sometimes, you want to expire all tokens of a user. For example, user changes his/her password and you want to force log out the user on all devices:

.. code-block:: python

from  djforge_redis_multitokens.tokens_auth import MultiToken

# after user changes password
def password_changed_handler(user):
    MultiToken.expire_all_tokens(user)

Get User From Token

When you have access to user's token, you can get the user associated with that token:

.. code-block:: python

MultiToken.get_user_from_token(key)

Notes:

• Then key here is a str object, so the get_user_from_token method expects the key as a string.
• MultiToken.get_user_from_token returns a User which is defined by settings.AUTH_USER_MODEL.

Immortal Tokens

If you want your tokens to never expire, you need to do 2 things:

1. Set TIMEOUT to None in CACHES:

.. code-block:: python

CACHES = {

    # other Redis db definitions above

    # tokens db definition
    'tokens': {
        'BACKEND': 'redis_cache.RedisCache',
        'LOCATION': 'localhost:6379',
        'OPTIONS': {
            'DB': 2,
        },
        'TIMEOUT': None,
    }
}

2. Set OVERWRITE_NONE_TTL to False in DJFORGE_REDIS_MULTITOKENS:

.. code-block:: python

DJFORGE_REDIS_MULTITOKENS = {
    'REDIS_DB_NAME': 'custom_redis_db_name_for_tokens',
    'RESET_TOKEN_TTL_ON_USER_LOG_IN': True,
    'OVERWRITE_NONE_TTL': False,
}

How to Develop

• Clone the repo, go to the root directory(where setup.py is)
• pip install --editable .
• cd test_app/
• pip install -r requirements
• cd demo
• python manage.py migrate
• python manage.py test