382 lines
14 KiB
Python
382 lines
14 KiB
Python
# This Source Code Form is subject to the terms of the Mozilla Public
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# License, v. 2.0. If a copy of the MPL was not distributed with this
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# file, You can obtain one at http://mozilla.org/MPL/2.0/.
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import base64
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from copy import deepcopy
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import json
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import os
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try:
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from urllib.parse import urlparse
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except ImportError: # pragma nocover
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from urlparse import urlparse
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import six
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import http_ece
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import requests
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives.asymmetric import ec
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from py_vapid import Vapid
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class WebPushException(Exception):
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pass
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class CaseInsensitiveDict(dict):
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"""A dictionary that has case-insensitive keys"""
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def __init__(self, data={}, **kwargs):
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for key in data:
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dict.__setitem__(self, key.lower(), data[key])
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self.update(kwargs)
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def __contains__(self, key):
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return dict.__contains__(self, key.lower())
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def __setitem__(self, key, value):
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dict.__setitem__(self, key.lower(), value)
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def __getitem__(self, key):
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return dict.__getitem__(self, key.lower())
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def __delitem__(self, key):
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dict.__delitem__(self, key.lower())
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def get(self, key, default=None):
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try:
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return self.__getitem__(key)
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except KeyError:
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return default
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def update(self, data):
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for key in data:
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self.__setitem__(key, data[key])
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class WebPusher:
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"""WebPusher encrypts a data block using HTTP Encrypted Content Encoding
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for WebPush.
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See https://tools.ietf.org/html/draft-ietf-webpush-protocol-04
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for the current specification, and
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https://developer.mozilla.org/en-US/docs/Web/API/Push_API for an
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overview of Web Push.
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Example of use:
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The javascript promise handler for PushManager.subscribe()
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receives a subscription_info object. subscription_info.getJSON()
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will return a JSON representation.
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(e.g.
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.. code-block:: javascript
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subscription_info.getJSON() ==
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{"endpoint": "https://push.server.com/...",
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"keys":{"auth": "...", "p256dh": "..."}
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}
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)
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This subscription_info block can be stored.
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To send a subscription update:
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.. code-block:: python
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# Optional
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# headers = py_vapid.sign({"aud": "https://push.server.com/",
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"sub": "mailto:your_admin@your.site.com"})
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data = "Mary had a little lamb, with a nice mint jelly"
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WebPusher(subscription_info).send(data, headers)
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"""
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subscription_info = {}
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valid_encodings = [
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# "aesgcm128", # this is draft-0, but DO NOT USE.
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"aesgcm", # draft-httpbis-encryption-encoding-01
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"aes128gcm" # draft-httpbis-encryption-encoding-04
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]
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def __init__(self, subscription_info, requests_session=None):
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"""Initialize using the info provided by the client PushSubscription
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object (See
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https://developer.mozilla.org/en-US/docs/Web/API/PushManager/subscribe)
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:param subscription_info: a dict containing the subscription_info from
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the client.
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:type subscription_info: dict
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:param requests_session: a requests.Session object to optimize requests
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to the same client.
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:type requests_session: requests.Session
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"""
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if requests_session is None:
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self.requests_method = requests
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else:
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self.requests_method = requests_session
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if 'endpoint' not in subscription_info:
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raise WebPushException("subscription_info missing endpoint URL")
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self.subscription_info = deepcopy(subscription_info)
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self.auth_key = self.receiver_key = None
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if 'keys' in subscription_info:
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keys = self.subscription_info['keys']
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for k in ['p256dh', 'auth']:
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if keys.get(k) is None:
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raise WebPushException("Missing keys value: {}".format(k))
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if isinstance(keys[k], six.string_types):
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keys[k] = bytes(keys[k].encode('utf8'))
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receiver_raw = base64.urlsafe_b64decode(
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self._repad(keys['p256dh']))
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if len(receiver_raw) != 65 and receiver_raw[0] != "\x04":
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raise WebPushException("Invalid p256dh key specified")
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self.receiver_key = receiver_raw
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self.auth_key = base64.urlsafe_b64decode(
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self._repad(keys['auth']))
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def _repad(self, data):
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"""Add base64 padding to the end of a string, if required"""
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return data + b"===="[:len(data) % 4]
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def encode(self, data, content_encoding="aesgcm"):
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"""Encrypt the data.
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:param data: A serialized block of byte data (String, JSON, bit array,
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etc.) Make sure that whatever you send, your client knows how
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to understand it.
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:type data: str
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:param content_encoding: The content_encoding type to use to encrypt
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the data. Defaults to draft-01 "aesgcm". Latest draft-04 is
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"aes128gcm", however not all clients may be able to use this
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format.
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:type content_encoding: enum("aesgcm", "aes128gcm")
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"""
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# Salt is a random 16 byte array.
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if not data:
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return
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if not self.auth_key or not self.receiver_key:
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raise WebPushException("No keys specified in subscription info")
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salt = None
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if content_encoding not in self.valid_encodings:
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raise WebPushException("Invalid content encoding specified. "
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"Select from " +
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json.dumps(self.valid_encodings))
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if (content_encoding == "aesgcm"):
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salt = os.urandom(16)
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# The server key is an ephemeral ECDH key used only for this
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# transaction
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server_key = ec.generate_private_key(ec.SECP256R1, default_backend())
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crypto_key = base64.urlsafe_b64encode(
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server_key.public_key().public_numbers().encode_point()
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).strip(b'=')
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if isinstance(data, six.string_types):
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data = bytes(data.encode('utf8'))
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encrypted = http_ece.encrypt(
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data,
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salt=salt,
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keyid=crypto_key.decode(),
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private_key=server_key,
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dh=self.receiver_key,
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auth_secret=self.auth_key,
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version=content_encoding)
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reply = CaseInsensitiveDict({
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'crypto_key': crypto_key,
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'body': encrypted,
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})
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if salt:
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reply['salt'] = base64.urlsafe_b64encode(salt).strip(b'=')
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return reply
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def as_curl(self, endpoint, encoded_data, headers):
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"""Return the send as a curl command.
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Useful for debugging. This will write out the encoded data to a local
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file named `encrypted.data`
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:param endpoint: Push service endpoint URL
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:type endpoint: basestring
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:param encoded_data: byte array of encoded data
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:type encoded_data: bytearray
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:param headers: Additional headers for the send
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:type headers: dict
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:returns string
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"""
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header_list = [
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'-H "{}: {}" \\ \n'.format(
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key.lower(), val) for key, val in headers.items()
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]
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data = ""
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if encoded_data:
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with open("encrypted.data", "wb") as f:
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f.write(encoded_data)
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data = "--data-binary @encrypted.data"
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if 'content-length' not in headers:
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header_list.append(
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'-H "content-length: {}" \\ \n'.format(len(data)))
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return ("""curl -vX POST {url} \\\n{headers}{data}""".format(
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url=endpoint, headers="".join(header_list), data=data))
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def send(self, data=None, headers=None, ttl=0, gcm_key=None, reg_id=None,
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content_encoding="aesgcm", curl=False, timeout=None):
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"""Encode and send the data to the Push Service.
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:param data: A serialized block of data (see encode() ).
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:type data: str
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:param headers: A dictionary containing any additional HTTP headers.
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:type headers: dict
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:param ttl: The Time To Live in seconds for this message if the
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recipient is not online. (Defaults to "0", which discards the
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message immediately if the recipient is unavailable.)
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:type ttl: int
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:param gcm_key: API key obtained from the Google Developer Console.
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Needed if endpoint is https://android.googleapis.com/gcm/send
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:type gcm_key: string
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:param reg_id: registration id of the recipient. If not provided,
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it will be extracted from the endpoint.
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:type reg_id: str
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:param content_encoding: ECE content encoding (defaults to "aesgcm")
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:type content_encoding: str
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:param curl: Display output as `curl` command instead of sending
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:type curl: bool
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:param timeout: POST requests timeout
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:type timeout: float or tuple
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"""
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# Encode the data.
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if headers is None:
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headers = dict()
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encoded = {}
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headers = CaseInsensitiveDict(headers)
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if data:
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encoded = self.encode(data)
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# Append the p256dh to the end of any existing crypto-key
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crypto_key = headers.get("crypto-key", "")
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if crypto_key:
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# due to some confusion by a push service provider, we should
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# use ';' instead of ',' to append the headers.
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# see https://github.com/webpush-wg/webpush-encryption/issues/6
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crypto_key += ';'
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crypto_key += ("dh=" + encoded["crypto_key"].decode('utf8'))
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headers.update({
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'crypto-key': crypto_key,
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'content-encoding': content_encoding,
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'encryption': "salt=" + encoded['salt'].decode('utf8'),
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})
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if gcm_key:
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endpoint = 'https://android.googleapis.com/gcm/send'
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reg_ids = []
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if not reg_id:
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reg_id = self.subscription_info['endpoint'].rsplit('/', 1)[-1]
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reg_ids.append(reg_id)
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gcm_data = dict()
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gcm_data['registration_ids'] = reg_ids
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if data:
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gcm_data['raw_data'] = base64.b64encode(
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encoded.get('body')).decode('utf8')
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gcm_data['time_to_live'] = int(
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headers['ttl'] if 'ttl' in headers else ttl)
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encoded_data = json.dumps(gcm_data)
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headers.update({
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'Authorization': 'key='+gcm_key,
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'Content-Type': 'application/json',
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})
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else:
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encoded_data = encoded.get('body')
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endpoint = self.subscription_info['endpoint']
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if 'ttl' not in headers or ttl:
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headers['ttl'] = str(ttl or 0)
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# Additionally useful headers:
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# Authorization / Crypto-Key (VAPID headers)
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if curl:
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return self.as_curl(endpoint, encoded_data, headers)
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return self.requests_method.post(endpoint,
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data=encoded_data,
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headers=headers,
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timeout=timeout)
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def webpush(subscription_info,
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data=None,
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vapid_private_key=None,
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vapid_claims=None,
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content_encoding="aesgcm",
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curl=False,
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timeout=None):
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"""
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One call solution to endcode and send `data` to the endpoint
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contained in `subscription_info` using optional VAPID auth headers.
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in example:
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.. code-block:: python
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from pywebpush import python
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webpush(
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subscription_info={
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"endpoint": "https://push.example.com/v1/abcd",
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"keys": {"p256dh": "0123abcd...",
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"auth": "001122..."}
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},
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data="Mary had a little lamb, with a nice mint jelly",
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vapid_private_key="path/to/key.pem",
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vapid_claims={"sub": "YourNameHere@example.com"}
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)
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No additional method call is required. Any non-success will throw a
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`WebPushException`.
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:param subscription_info: Provided by the client call
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:type subscription_info: dict
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:param data: Serialized data to send
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:type data: str
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:param vapid_private_key: Vapid instance or path to vapid private key PEM \
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or encoded str
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:type vapid_private_key: Union[Vapid, str]
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:param vapid_claims: Dictionary of claims ('sub' required)
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:type vapid_claims: dict
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:param content_encoding: Optional content type string
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:type content_encoding: str
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:param curl: Return as "curl" string instead of sending
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:type curl: bool
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:param timeout: POST requests timeout
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:type timeout: float or tuple
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:return requests.Response or string
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"""
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vapid_headers = None
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if vapid_claims:
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if not vapid_claims.get('aud'):
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url = urlparse(subscription_info.get('endpoint'))
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aud = "{}://{}".format(url.scheme, url.netloc)
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vapid_claims['aud'] = aud
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if not vapid_private_key:
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raise WebPushException("VAPID dict missing 'private_key'")
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if isinstance(vapid_private_key, Vapid):
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vv = vapid_private_key
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elif os.path.isfile(vapid_private_key):
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# Presume that key from file is handled correctly by
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# py_vapid.
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vv = Vapid.from_file(
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private_key_file=vapid_private_key) # pragma no cover
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else:
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vv = Vapid.from_string(private_key=vapid_private_key)
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vapid_headers = vv.sign(vapid_claims)
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result = WebPusher(subscription_info).send(
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data,
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vapid_headers,
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content_encoding=content_encoding,
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curl=curl,
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timeout=timeout,
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)
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if not curl and result.status_code > 202:
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raise WebPushException("Push failed: {}: {}".format(
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result, result.text))
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return result
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