Webpush Data encryption library for Python
==========================================

|Build Status| |Requirements Status|

This library is available on `pypi as
pywebpush <https://pypi.python.org/pypi/pywebpush>`__. Source is
available on `github <https://github.com/mozilla-services/pywebpush>`__.
Please note: This library was designated as a ``Critical Project`` by
PyPi, it is currently maintained by `a single
person <https://xkcd.com/2347/>`__. I still accept PRs and Issues, but
make of that what you will.

Installation
------------

You’ll need to run ``python -m venv venv``. Then

.. code:: bash

   venv/bin/pip install -r requirements.txt
   venv/bin/python -m pip install -e .

Usage
-----

In the browser, the promise handler for
`registration.pushManager.subscribe() <https://developer.mozilla.org/en-US/docs/Web/API/PushManager/subscribe>`__
returns a
`PushSubscription <https://developer.mozilla.org/en-US/docs/Web/API/PushSubscription>`__
object. This object has a .toJSON() method that will return a JSON
object that contains all the info we need to encrypt and push data.

As illustration, a ``subscription_info`` object may look like:

.. code:: json

   {"endpoint": "https://updates.push.services.mozilla.com/push/v1/gAA...", "keys": {"auth": "k8J...", "p256dh": "BOr..."}}

How you send the PushSubscription data to your backend, store it
referenced to the user who requested it, and recall it when there’s a
new push subscription update is left as an exercise for the reader.

Sending Data using ``webpush()`` One Call
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In many cases, your code will be sending a single message to many
recipients. There’s a “One Call” function which will make things easier.

.. code:: python

   from pywebpush import webpush

   webpush(subscription_info,
           data,
           vapid_private_key="Private Key or File Path[1]",
           vapid_claims={"sub": "mailto:YourEmailAddress"})

This will encode ``data``, add the appropriate VAPID auth headers if
required and send it to the push server identified in the
``subscription_info`` block.

**Parameters**

*subscription_info* - The ``dict`` of the subscription info (described
above).

*data* - can be any serial content (string, bit array, serialized JSON,
etc), but be sure that your receiving application is able to parse and
understand it. (e.g. ``data = "Mary had a little lamb."``)

*content_type* - specifies the form of Encryption to use, either
``'aes128gcm'`` or the deprecated ``'aesgcm'``. NOTE that not all User
Agents can decrypt ``'aesgcm'``, so the library defaults to the RFC 8188
standard form.

*vapid_claims* - a ``dict`` containing the VAPID claims required for
authorization (See
`py_vapid <https://github.com/web-push-libs/vapid/tree/master/python>`__
for more details). If ``aud`` is not specified, pywebpush will attempt
to auto-fill from the ``endpoint``.

*vapid_private_key* - Either a path to a VAPID EC2 private key PEM file,
or a string containing the DER representation. (See
`py_vapid <https://github.com/web-push-libs/vapid/tree/master/python>`__
for more details.) The ``private_key`` may be a base64 encoded DER
formatted private key, or the path to an OpenSSL exported private key
file.

e.g. the output of:

.. code:: bash

   openssl ecparam -name prime256v1 -genkey -noout -out private_key.pem

**Example**

.. code:: python

   from pywebpush import webpush, WebPushException

   try:
       webpush(
           subscription_info={
               "endpoint": "https://push.example.com/v1/12345",
               "keys": {
                   "p256dh": "0123abcde...",
                   "auth": "abc123..."
               }},
           data="Mary had a little lamb, with a nice mint jelly",
           vapid_private_key="path/to/vapid_private.pem",
           vapid_claims={
                   "sub": "mailto:YourNameHere@example.org",
               }
       )
   except WebPushException as ex:
       print("I'm sorry, Dave, but I can't do that: {}", repr(ex))
       # Mozilla returns additional information in the body of the response.
       if ex.response is not None and ex.response.json():
           extra = ex.response.json()
           print("Remote service replied with a {}:{}, {}",
                 extra.code,
                 extra.errno,
                 extra.message
                 )

Methods
~~~~~~~

If you expect to resend to the same recipient, or have more needs than
just sending data quickly, you can pass just
``wp = WebPusher(subscription_info)``. This will return a ``WebPusher``
object.

The following methods are available:

``.send(data, headers={}, ttl=0, gcm_key="", reg_id="", content_encoding="aes128gcm", curl=False, timeout=None)``
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Send the data using additional parameters. On error, returns a
``WebPushException``

**Parameters**

*data* Binary string of data to send

*headers* A ``dict`` containing any additional headers to send

*ttl* Message Time To Live on Push Server waiting for the client to
reconnect (in seconds)

*gcm_key* Google Cloud Messaging key (if using the older GCM push
system) This is the API key obtained from the Google Developer Console.

*reg_id* Google Cloud Messaging registration ID (will be extracted from
endpoint if not specified)

*content_encoding* ECE content encoding type (defaults to “aes128gcm”)

*curl* Do not execute the POST, but return as a ``curl`` command. This
will write the encrypted content to a local file named
``encrpypted.data``. This command is meant to be used for debugging
purposes.

*timeout* timeout for requests POST query. See `requests
documentation <http://docs.python-requests.org/en/master/user/quickstart/#timeouts>`__.

**Example**

to send from Chrome using the old GCM mode:

.. code:: python

   WebPusher(subscription_info).send(data, headers, ttl, gcm_key)

``.encode(data, content_encoding="aes128gcm")``
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Encode the ``data`` for future use. On error, returns a
``WebPushException``

**Parameters**

*data* Binary string of data to send

*content_encoding* ECE content encoding type (defaults to “aes128gcm”)

**Example**

.. code:: python

   encoded_data = WebPush(subscription_info).encode(data)

Stand Alone Webpush
-------------------

If you’re not really into coding your own solution, there’s also a
“stand-alone” ``pywebpush`` command in the ./bin directory.

This uses two files:

-  the *data* file, which contains the message to send, in whatever form
   you like.
-  the *subscription info* file, which contains the subscription
   information as JSON encoded data. This is usually returned by the
   Push ``subscribe`` method and looks something like:

.. code:: json

   {"endpoint": "https://push...",
    "keys": {
        "auth": "ab01...",
        "p256dh": "aa02..."
    }}

If you’re interested in just testing your applications WebPush
interface, you could use the Command Line:

.. code:: bash

   ./bin/pywebpush --data stuff_to_send.data --info subscription.info

which will encrypt and send the contents of ``stuff_to_send.data``.

See ``./bin/pywebpush --help`` for available commands and options.

.. |Build Status| image:: https://travis-ci.org/web-push-libs/pywebpush.svg?branch=main
   :target: https://travis-ci.org/web-push-libs/pywebpush
.. |Requirements Status| image:: https://requires.io/github/web-push-libs/pywebpush/requirements.svg?branch=main
   :target: https://requires.io/github/web-push-libs/pywebpush/requirements/?branch=main
