django-titofisto 1.1.0

Django Time-Token File Storage

This is a simple extension to Django’s FileSystemStorage that adds a URL parameter carrying a shared token, which is only valid for a defined period of time.

Additionally, a like-wise time-constrained file upload slot mechanism is available.

Functionality

File storage with token-secured URLs

This is a drop-in replacement for the Django FileSystemStorage, usable if media files are served by Django itself. It does currently not work if media files are served from an independent web server.

The storage and its accompanying view do the following:

• When a URL to a storage file is generated, a HMAC-based token is generated

• The token and the timestamp when it was generated are appended as request parameters to the URL

• Upon retrieval of the file through the accompanying view, the requested file name and the passed timestamp are used to recalculate the HMAC-based token

• Only if the tokens match, and a configured timeout has not passed, is the file served

The signature-based token ensures that the token is invalidated when:

• The filename changes

• The timestamp changes

• The mtime of the file changes

• The SECRET_KEY changes

Time-constrained uplaod slot

The upload slot mechanism can be used to generically handle file uploads by clients that can not upload files with a regular request. One example for this is a client using GraphQL to talk to Django, because GraphQL does not support file uploads and rather suggests to do uplaods out-of-band.

With Titofisto’s upload slot mechanism, calling code can request a secure URL which it can hand out to a client. When the client POSTs its file to the endpoint, a previously provided callback is called to handle the uploaded file.

Installation

To add django-titofisto to a project, first add it as dependency to your project, e.g. using poetry:

$ poetry add django-titofisto

django-titofisto will use the base FileSystemStorage for almost everything, including determining the MEDIA_ROOT. It merely adds a token as URL parameter to whatever the base FileSystemStorage.url() method returns.

Add the following to your settings:

DEFAULT_FILE_STORAGE = "titofisto.TitofistoStorage"
TITOFISTO_TIMEOUT = 3600  # optional, this is the default
TITOFISTO_PARAM = "titofisto_token"  # optional, this is the default

Add the following to your URL config:

from django.conf import settings
from django.urls import include, path

urlpatterns += [
    path(settings.MEDIA_URL.removeprefix("/"), include("titofisto.urls")),
]

Django will start serving media files under the configured MEDIA_URL.

Provide public media files

Sometimes, there might be media files, for example favicons, you want to be accessible without any authentication. Per default, django-titofisto will serve all files stored in the directory public without a token. You can disable or configure this behavior using these settings:

TITOFISTO_USE_PUBLIC_NAMESPACE = True # optional, this is the default
TITOFISTO_PUBLIC_NAMESPACE = "public/" # optional, this is the default

Use the time-constrained upload slot

To enable the file upload mechanism, a setting must be set, because the default upload/ prefix could potentially shadow expected media file URLs:

TITOFISTO_ENABLE_UPLOAD = True
TITOFISTO_UPLOAD_NAMESPACE = "titofisto/upload/"

A simplified example for using the upload slot mechanism is:

from titofisto.views import TitofistoUploadView

def handle_file(request, pk):
    instance = MyModel.objects.get(pk=pk)
    instance.photo = request.FILES["photo"]
    instance.save()

# This gets an uplaod URL to pass on to the client
# On upload, the handler above will be called, with 15 as positional argument
upload_url = TitofistoUploadView.get_upload_slot(
    "mymodule.handle_file",
    (15,)
)

Credits

django-titofisto was developed for the AlekSIS school information system by its team:

Copyright © 2021, 2023 Dominik George <[e-mail]>
Copyright © 2021 Jonathan Weth <[e-mail]>