Enable JWT authentication in addition to old certificate authentication (#40)

apns2/client.py

@@ -3,11 +3,12 @@ import json
 import logging
 from enum import Enum
 
-from hyper import HTTP20Connection
-from hyper.tls import init_context
-
 from .errors import ConnectionFailed, exception_class_for_reason
 
+# We don't generally need to know about the Credentials subclasses except to
+# keep the old API, where APNsClient took a cert_file
+from .credentials import CertificateCredentials
+
 
 class NotificationPriority(Enum):
     Immediate = '10'
@@ -30,18 +31,22 @@ class APNsClient(object):
     DEFAULT_PORT = 443
     ALTERNATIVE_PORT = 2197
 
-    def __init__(self, cert_file, use_sandbox=False, use_alternative_port=False, proto=None, json_encoder=None, password=None):
-        ssl_context = init_context()
-        ssl_context.load_cert_chain(cert_file, password=password)
-        self._init_connection(use_sandbox, use_alternative_port, ssl_context, proto)
+    def __init__(self, credentials, use_sandbox=False, use_alternative_port=False, proto=None, json_encoder=None, password=None):
+        if credentials is None or isinstance(credentials, str):
+            self.__credentials = CertificateCredentials(credentials)
+        else:
+            self.__credentials = credentials
+        self._init_connection(use_sandbox, use_alternative_port, proto)
+
         self.__json_encoder = json_encoder
         self.__max_concurrent_streams = None
         self.__previous_server_max_concurrent_streams = None
 
-    def _init_connection(self, use_sandbox, use_alternative_port, ssl_context, proto):
+    def _init_connection(self, use_sandbox, use_alternative_port, proto):
         server = self.SANDBOX_SERVER if use_sandbox else self.LIVE_SERVER
         port = self.ALTERNATIVE_PORT if use_alternative_port else self.DEFAULT_PORT
-        self._connection = HTTP20Connection(server, port, ssl_context=ssl_context, force_proto=proto or 'h2')
+        self._connection = self.__credentials.create_connection(server, port,
+                                                                proto)
 
     def send_notification(self, token_hex, notification, topic, priority=NotificationPriority.Immediate,
                           expiration=None, collapse_id=None):
@@ -62,6 +67,10 @@ class APNsClient(object):
         if expiration is not None:
             headers['apns-expiration'] = '%d' % expiration
 
+        auth_header = self.__credentials.get_authorization_header(topic)
+        if auth_header is not None:
+            headers['authorization'] = auth_header
+
         if collapse_id is not None:
             headers['apns-collapse-id'] = collapse_id
 

apns2/credentials.py

@@ -0,0 +1,96 @@
+
+from hyper import HTTP20Connection
+from hyper.tls import init_context
+
+import jwt
+
+# For creating and comparing the time for the JWT token
+import time
+
+
+DEFAULT_TOKEN_LIFETIME = 3600
+DEFAULT_TOKEN_ENCRYPTION_ALGORITHM = 'ES256'
+
+
+# Abstract Base class. This should not be instantiated directly.
+class Credentials(object):
+
+    def __init__(self, ssl_context=None):
+        self.__ssl_context = ssl_context
+
+    # Creates a connection with the credentials, if available or necessary.
+    def create_connection(self, server, port, proto):
+        # self.__ssl_context may be none, and that's fine.
+        return HTTP20Connection(server, port,
+                                ssl_context=self.__ssl_context,
+                                force_proto=proto or 'h2')
+
+    def get_authorization_header(self, topic):
+        return None
+
+
+# Credentials subclass for certificate authentication
+class CertificateCredentials(Credentials):
+    def __init__(self, cert_file):
+        ssl_context = init_context()
+        ssl_context.load_cert_chain(cert_file)
+        super(CertificateCredentials, self).__init__(ssl_context)
+
+
+# Credentials subclass for JWT token based authentication
+class TokenCredentials(Credentials):
+    def __init__(self, auth_key_path, auth_key_id, team_id,
+                 encryption_algorithm=None, token_lifetime=None):
+        self.__auth_key = self._get_signing_key(auth_key_path)
+        self.__auth_key_id = auth_key_id
+        self.__team_id = team_id
+        self.__encryption_algorithm = DEFAULT_TOKEN_ENCRYPTION_ALGORITHM if \
+            encryption_algorithm is None else \
+            encryption_algorithm
+        self.__token_lifetime = DEFAULT_TOKEN_LIFETIME if \
+            token_lifetime is None else token_lifetime
+
+        # Dictionary of {topic: (issue time, ascii decoded token)}
+        self.__topicTokens = {}
+
+        # Use the default constructor because we don't have an SSL context
+        super(TokenCredentials, self).__init__()
+
+    def get_tokens(self):
+        return [val[1] for val in self.__topicTokens]
+
+    def get_authorization_header(self, topic):
+        token = self._get_or_create_topic_token(topic)
+        return 'bearer %s' % token
+
+    def _isExpiredToken(self, issueDate):
+        now = time.time()
+        return now < issueDate + DEFAULT_TOKEN_LIFETIME
+
+    def _get_or_create_topic_token(self, topic):
+        # dict of topic to issue date and JWT token
+        tokenPair = self.__topicTokens.get(topic)
+        if tokenPair is None or self._isExpiredToken(tokenPair[0]):
+            # Create a new token
+            issuedAt = time.time()
+            tokenDict = {'iss': self.__team_id,
+                         'iat': issuedAt
+                         }
+            headers = {'alg': self.__encryption_algorithm,
+                       'kid': self.__auth_key_id,
+                       }
+            jwtToken = jwt.encode(tokenDict, self.__auth_key,
+                                  algorithm=self.__encryption_algorithm,
+                                  headers=headers).decode('ascii')
+
+            self.__topicTokens[topic] = (issuedAt, jwtToken)
+            return jwtToken
+        else:
+            return tokenPair[1]
+
+    def _get_signing_key(self, key_path):
+        secret = ''
+        if key_path:
+            with open(key_path) as f:
+                secret = f.read()
+        return secret