Add webpush support

4 files changed, 215 insertions, 10 deletions

diff --git a/DEVELOPMENT.md b/DEVELOPMENT.md
index 837cbaa..cf00e6a 100644
--- a/DEVELOPMENT.md
+++ b/DEVELOPMENT.md
@@ -6,5 +6,5 @@ Here's some general stuff to keep in mind, and some work that needs to be done
 * Current TODOs:
     * Testing - test 2.3 stuff and verify it works: TODO: media updating
     * 2.4 support:
-        * Push API
+        * Document and add tests for webpush
         
\ No newline at end of file
diff --git a/docs/index.rst b/docs/index.rst
index dc9423f..ef96273 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -529,6 +529,23 @@ Report dicts
                         # will set this field to True.
     }
     
+Push subscription dicts
+~~~~~~~~~~~~~~~~~~~~~~~
+.. _push subscription dict:
+
+.. code-block:: python
+
+    mastodon.push_subscription()
+    # Returns the following dictionary
+    {
+        'id': # Numerical id of the push subscription
+        'endpoint': # Endpoint URL for the subscription
+        'server_key': # Server pubkey used for signature verification
+        'alerts': # Subscribed events - dict that may contain keys 'follow',
+                  # 'favourite', 'reblog' and 'mention', with value True
+                  # if webpushes have been requested for those events.
+    }
+    
 App registration and user authentication
 ----------------------------------------
 Before you can use the mastodon API, you have to register your 
@@ -805,6 +822,7 @@ StreamListener
 .. automethod:: StreamListener.on_update
 .. automethod:: StreamListener.on_notification
 .. automethod:: StreamListener.on_delete
+.. automethod:: StreamListener.on_abort
 .. automethod:: StreamListener.handle_heartbeat
 
 CallbackStreamListener
@@ -812,12 +830,31 @@ CallbackStreamListener
 
 .. autoclass:: CallbackStreamListener
 
-.. _Mastodon: https://github.com/tootsuite/mastodon
-.. _Mastodon flagship instance: http://mastodon.social/
-.. _Mastodon api docs: https://github.com/tootsuite/documentation/
+Push subscriptions
+------------------
+These functions allow you to manage webpush subscriptions and to decrypt received
+pushes. Note that the intended setup is not mastodon pushing directly to a users client - 
+the push endpoint should usually be a relay server that then takes care of delivering the 
+(encrypted) push to the end user via some mechanism, where it can then be decrypted and
+displayed.
+
+Mastodon allows an application to have one webpush subscription per user at a time.
+
+.. automethod:: Mastodon.push_subscription
+.. automethod:: Mastodon.push_subscription_set
+.. automethod:: Mastodon.push_subscription_update
+
+.. push_subscription_generate_keys():
+
+.. automethod:: Mastodon.push_subscription_generate_keys
+.. automethod:: Mastodon.push_subscription_decrypt_push
 
 Acknowledgements
 ----------------
 Mastodon.py contains work by a large amount of contributors, many of which have
 put significant work into making it a better library. You can find some information
 about who helped with which particular feature or fix in the changelog.
+
+.. _Mastodon: https://github.com/tootsuite/mastodon
+.. _Mastodon flagship instance: http://mastodon.social/
+.. _Mastodon api docs: https://github.com/tootsuite/documentation/
\ No newline at end of file
diff --git a/mastodon/Mastodon.py b/mastodon/Mastodon.py
index 17f059f..ed2a1f7 100644
--- a/mastodon/Mastodon.py
+++ b/mastodon/Mastodon.py
@@ -20,6 +20,11 @@ import threading
 import sys
 import six
 from decorator import decorate
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives.asymmetric import ec
+import http_ece
+import base64
+import json
 
 try:
     from urllib.parse import urlparse
@@ -126,15 +131,16 @@ class Mastodon:
             __DICT_VERSION_ACCOUNT), __DICT_VERSION_STATUS), __DICT_VERSION_HASHTAG)
     __DICT_VERSION_ACTIVITY = "2.1.2" 
     __DICT_VERSION_REPORT = "1.1.0"
+    __DICT_VERSION_PUSH = "2.4.0"
     
     ###
     # Registering apps
     ###
     @staticmethod
-    def create_app(client_name, scopes=['read', 'write', 'follow'], redirect_uris=None, website=None, to_file=None,
+    def create_app(client_name, scopes=['read', 'write', 'follow', 'push'], redirect_uris=None, website=None, to_file=None,
                    api_base_url=__DEFAULT_BASE_URL, request_timeout=__DEFAULT_TIMEOUT):
         """
-        Create a new app with given `client_name` and `scopes` (read, write, follow)
+        Create a new app with given `client_name` and `scopes` (read, write, follow, push)
 
         Specify `redirect_uris` if you want users to be redirected to a certain page after authenticating.
         Specify `to_file` to persist your apps info to a file so you can use them in the constructor.
@@ -303,7 +309,7 @@ class Mastodon:
         return Mastodon.__SUPPORTED_MASTODON_VERSION
     
     def auth_request_url(self, client_id=None, redirect_uris="urn:ietf:wg:oauth:2.0:oob",
-                         scopes=['read', 'write', 'follow']):
+                         scopes=['read', 'write', 'follow', 'push']):
         """Returns the url that a client needs to request the grant from the server.
         """
         if client_id is None:
@@ -323,7 +329,7 @@ class Mastodon:
 
     def log_in(self, username=None, password=None,
                code=None, redirect_uri="urn:ietf:wg:oauth:2.0:oob", refresh_token=None,
-               scopes=['read', 'write', 'follow'], to_file=None):
+               scopes=['read', 'write', 'follow', 'push'], to_file=None):
         """
         Get the access token for a user.
         
@@ -950,6 +956,19 @@ class Mastodon:
         return self.__api_request('GET', '/api/v1/custom_emojis')
 
     ###
+    # Reading data: Webpush subscriptions
+    ###
+    @api_version("2.4.0", "2.4.0", __DICT_VERSION_PUSH)
+    def push_subscription(self):
+        """
+        Fetch the current push subscription the logged-in user has for this app.
+
+        Returns a `push subscription dict`_.
+        
+        """
+        return self.__api_request('GET', '/api/v1/push/subscription')
+
+    ###
     # Writing data: Statuses
     ###
     @api_version("1.0.0", "2.3.0", __DICT_VERSION_STATUS)    
@@ -1455,6 +1474,8 @@ class Mastodon:
         """
         Update the metadata of the media file with the given `id`. `description` and 
         `focus` are as in `media_post()`_ .
+        
+        Returns the updated `media dict`_.
         """
         id = self.__unpack_id(id)
 
@@ -1484,6 +1505,136 @@ class Mastodon:
         self.__api_request('DELETE', '/api/v1/domain_blocks', params)
 
     ###
+    # Writing data: Push subscriptions
+    ###
+    @api_version("2.4.0", "2.4.0", __DICT_VERSION_PUSH)
+    def push_subscription_set(self, endpoint, encrypt_params, follow_events=False, 
+                              favourite_events=False, reblog_events=False, 
+                              mention_events=False):
+        """
+        Sets up or modifies the push subscription the logged-in user has for this app.
+        
+        `endpoint` is the endpoint URL mastodon should call for pushes. Note that mastodon
+        requires https for this URL. `encrypt_params` is a dict with key parameters that allow
+        the server to encrypt data for you: A public key `pubkey` and a shared secret `auth`.
+        You can generate this as well as the corresponding private key using the 
+        `push_subscription_generate_keys()`_ .
+        
+        The rest of the parameters controls what kind of events you wish to subscribe to.
+        
+        Returns a `push subscription dict`_.
+        """
+        endpoint = Mastodon.__protocolize(endpoint)
+        
+        push_pubkey_b64 = base64.b64encode(encrypt_params['pubkey'])
+        push_auth_b64 = base64.b64encode(encrypt_params['auth'])
+        
+        params = {
+            'subscription[endpoint]': endpoint,
+            'subscription[keys][p256dh]': push_pubkey_b64,
+            'subscription[keys][auth]': push_auth_b64
+        }
+        
+        if follow_events == True:
+            params['data[alerts][follow]'] = True
+        
+        if favourite_events == True:
+            params['data[alerts][favourite]'] = True
+            
+        if reblog_events == True:
+            params['data[alerts][reblog]'] = True
+            
+        if mention_events == True:
+            params['data[alerts][mention]'] = True
+            
+        return self.__api_request('POST', '/api/v1/push/subscription', params)
+    
+    @api_version("2.4.0", "2.4.0", __DICT_VERSION_PUSH)
+    def push_subscription_update(self, endpoint, encrypt_params, follow_events=False, 
+                              favourite_events=False, reblog_events=False, 
+                              mention_events=False):
+        """
+        Modifies what kind of events the app wishes to subscribe to.
+        
+        Returns the updated `push subscription dict`_.
+        """
+        params = {}
+        
+        if follow_events == True:
+            params['data[alerts][follow]'] = True
+        
+        if favourite_events == True:
+            params['data[alerts][favourite]'] = True
+            
+        if reblog_events == True:
+            params['data[alerts][reblog]'] = True
+            
+        if mention_events == True:
+            params['data[alerts][mention]'] = True
+            
+        return self.__api_request('PUT', '/api/v1/push/subscription', params)
+    
+    @api_version("2.4.0", "2.4.0", "2.4.0")
+    def push_subscription_delete(self):
+        """
+        Remove the current push subscription the logged-in user has for this app.
+        """
+        self.__api_request('DELETE', '/api/v1/push/subscription')
+     
+     
+    ###
+    # Push subscription crypto utilities
+    ###     
+    def push_subscription_generate_keys(self):
+        """
+        Generates a private key, public key and shared secret for use in webpush subscriptionss.
+        
+        Returns two dicts: One with the private key and shared secret and another with the 
+        public key and shared secret.
+        """
+        push_key_pair = ec.generate_private_key(ec.SECP256R1(), default_backend())
+        push_key_priv = push_key_pair.private_numbers().private_value
+        push_key_pub = push_key_pair.public_key().public_numbers().encode_point() 
+        push_shared_secret = os.urandom(16)
+        
+        priv_dict = {
+            'privkey': push_key_priv,
+            'auth': push_shared_secret
+        }
+        
+        pub_dict = {
+            'pubkey': push_key_pub,
+            'auth': push_shared_secret
+        }
+        
+        return priv_dict, pub_dict
+    
+    def push_subscription_decrypt_push(self, data, decrypt_params, encryption_header, crypto_key_header):
+        """
+        Decrypts `data` received in a webpush request. Requires the private key dict 
+        from `push_subscription_generate_keys()`_ (`decrypt_params`) as well as the 
+        Encryption and server Crypto-Key headers from the received webpush
+        
+        Returns the decoded webpush.
+        """
+        salt = self.__decode_webpush_b64(encryption_header.split("salt=")[1].strip())
+        dhparams = self.__decode_webpush_b64(crypto_key_header.split("dh=")[1].split(";")[0].strip())
+        p256ecdsa = self.__decode_webpush_b64(crypto_key_header.split("p256ecdsa=")[1].strip())
+        dec_key = ec.derive_private_key(decrypt_params['privkey'], ec.SECP256R1(), default_backend())
+        decrypted = http_ece.decrypt(
+            data,
+            salt = salt,
+            key = p256ecdsa,
+            private_key = dec_key, 
+            dh = dhparams, 
+            auth_secret=decrypt_params['auth'],
+            keylabel = "P-256",
+            version = "aesgcm"
+        )
+        
+        return json.loads(decrypted.decode('utf-8'), object_hook = Mastodon.__json_hooks)
+    
+    ###
     # Pagination
     ###
     def fetch_next(self, previous_page):
@@ -1983,7 +2134,16 @@ class Mastodon:
             return id["id"]
         else:
             return id
-        
+    
+    def __decode_webpush_b64(self, data):
+        """
+        Re-pads and decodes urlsafe base64.
+        """
+        missing_padding = len(data) % 4
+        if missing_padding != 0:
+            data += '=' * (4 - missing_padding)
+        return base64.urlsafe_b64decode(data)
+    
     def __get_token_expired(self):
         """Internal helper for oauth code"""
         return self._token_expired < datetime.datetime.now()
diff --git a/setup.py b/setup.py
index 69feee7..48c2f56 100644
--- a/setup.py
+++ b/setup.py
@@ -10,7 +10,15 @@ setup(name='Mastodon.py',
       description='Python wrapper for the Mastodon API',
       packages=['mastodon'],
       setup_requires=['pytest-runner'],
-      install_requires=['requests', 'python-dateutil', 'six', 'pytz', 'decorator>=4.0.0'],
+      install_requires=[
+          'requests', 
+          'python-dateutil', 
+          'six', 
+          'pytz', 
+          'decorator>=4.0.0', 
+          'http_ece>=1.0.5',
+          'cryptography>=1.6.0'
+      ],
       tests_require=test_deps,
       extras_require=extras,
       url='https://github.com/halcy/Mastodon.py',