- Handle auto renewal of session authentication data

- Sub-class requests.Session as InfiniteSession class and handle
a 401 and 403 response as needed
- Add kwarg to client to allow for auto renewal of session auth
- Fix Cloudant auto connect bug

Author: alfinkel

src/cloudant/_2to3.py

@@ -33,6 +33,7 @@
 if PY2:
     # pylint: disable=wrong-import-position,no-name-in-module,import-error,unused-import
     from urllib import quote as url_quote, quote_plus as url_quote_plus
+    from urlparse import urlparse as url_parse
     from ConfigParser import RawConfigParser
 
     def iteritems_(adict):
@@ -53,7 +54,9 @@ def next_(itr):
         """
         return itr.next()
 else:
-    from urllib.parse import quote as url_quote, quote_plus as url_quote_plus  # pylint: disable=wrong-import-position,no-name-in-module,import-error,ungrouped-imports
+    from urllib.parse import urlparse as url_parse  # pylint: disable=wrong-import-position,no-name-in-module,import-error,ungrouped-imports
+    from urllib.parse import quote as url_quote  # pylint: disable=wrong-import-position,no-name-in-module,import-error,ungrouped-imports
+    from urllib.parse import quote_plus as url_quote_plus  # pylint: disable=wrong-import-position,no-name-in-module,import-error,ungrouped-imports
     from configparser import RawConfigParser  # pylint: disable=wrong-import-position,no-name-in-module,import-error
 
     def iteritems_(adict):

src/cloudant/_common_util.py

@@ -21,8 +21,9 @@
 import platform
 from collections import Sequence
 import json
+from requests import Session
 
-from ._2to3 import STRTYPE, NONETYPE, UNITYPE, iteritems_
+from ._2to3 import STRTYPE, NONETYPE, UNITYPE, iteritems_, url_parse
 from .error import CloudantArgumentError
 
 # Library Constants
@@ -288,3 +289,40 @@ class _Code(str):
     """
     def __new__(cls, code):
         return str.__new__(cls, code)
+
+class InfiniteSession(Session):
+    """
+    This class provides for the ability to automatically renew session login
+    information in the event of expired session authentication.
+    """
+
+    def __init__(self, username, password, server_url):
+        super(InfiniteSession, self).__init__()
+        self._username = username
+        self._password = password
+        self._server_url = server_url
+
+    def request(self, method, url, **kwargs):
+        """
+        Overrides ``requests.Session.request`` to perform a POST to the
+        _session endpoint to renew Session cookie authentication settings and
+        then retry the original request, if necessary.
+        """
+        resp = super(InfiniteSession, self).request(method, url, **kwargs)
+        path = url_parse(url).path.lower()
+        post_to_session = method.upper() == 'POST' and path == '/_session'
+        is_expired = any((
+            resp.status_code == 403 and
+            resp.json().get('error') == 'credentials_expired',
+            resp.status_code == 401
+        ))
+        if not post_to_session and is_expired:
+            super(InfiniteSession, self).request(
+                'POST',
+                '/'.join([self._server_url, '_session']),
+                data={'name': self._username, 'password': self._password},
+                headers={'Content-Type': 'application/x-www-form-urlencoded'}
+            )
+            resp = super(InfiniteSession, self).request(method, url, **kwargs)
+
+        return resp

src/cloudant/client.py

@@ -25,7 +25,11 @@
 from .database import CloudantDatabase, CouchDatabase
 from .feed import Feed, InfiniteFeed
 from .error import CloudantException, CloudantArgumentError
-from ._common_util import USER_AGENT, append_response_error_content
+from ._common_util import (
+    USER_AGENT,
+    append_response_error_content,
+    InfiniteSession
+)
 
 
 class CouchDB(dict):
@@ -49,6 +53,9 @@ class CouchDB(dict):
         configuring requests.
     :param bool connect: Keyword argument, if set to True performs the call to
         connect as part of client construction.  Default is False.
+    :param bool auto_renew: Keyword argument, if set to True performs
+        automatic renewal of expired session authentication settings.
+        Default is False.
     """
     _DATABASE_CLASS = CouchDatabase
 
@@ -63,7 +70,9 @@ def __init__(self, user, auth_token, admin_party=False, **kwargs):
         self.encoder = kwargs.get('encoder') or json.JSONEncoder
         self.adapter = kwargs.get('adapter')
         self.r_session = None
-        if kwargs.get('connect', False):
+        self._auto_renew = kwargs.get('auto_renew', False)
+        connect_to_couch = kwargs.get('connect', False)
+        if connect_to_couch and self._DATABASE_CLASS == CouchDatabase:
             self.connect()
 
     def connect(self):
@@ -74,7 +83,14 @@ def connect(self):
         if self.r_session:
             return
 
-        self.r_session = requests.Session()
+        if self._auto_renew and not self.admin_party:
+            self.r_session = InfiniteSession(
+                self._user,
+                self._auth_token,
+                self.server_url
+            )
+        else:
+            self.r_session = requests.Session()
         # If a Transport Adapter was supplied add it to the session
         if self.adapter is not None:
             self.r_session.mount(self.server_url, self.adapter)
@@ -398,7 +414,6 @@ class Cloudant(CouchDB):
 
     def __init__(self, cloudant_user, auth_token, **kwargs):
         super(Cloudant, self).__init__(cloudant_user, auth_token, **kwargs)
-
         self._client_user_header = {'User-Agent': USER_AGENT}
         account = kwargs.get('account')
         url = kwargs.get('url')
@@ -413,6 +428,9 @@ def __init__(self, cloudant_user, auth_token, **kwargs):
         if self.server_url is None:
             raise CloudantException('You must provide a url or an account.')
 
+        if kwargs.get('connect', False):
+            self.connect()
+
     def db_updates(self, raw_data=False, **kwargs):
         """
         Returns the ``_db_updates`` feed iterator.  The ``_db_updates`` feed can