Use Python 3.6+ ISO time functions

Refs SAML-Toolkits#289

src/onelogin/saml2/utils.py

@@ -10,7 +10,6 @@
 import base64
 import warnings
 from copy import deepcopy
-import calendar
 from datetime import datetime
 from hashlib import sha1, sha256, sha384, sha512
 from isodate import parse_duration as duration_parser
@@ -58,10 +57,6 @@ class OneLogin_Saml2_Utils:
     RESPONSE_SIGNATURE_XPATH = '/samlp:Response/ds:Signature'
     ASSERTION_SIGNATURE_XPATH = '/samlp:Response/saml:Assertion/ds:Signature'
 
-    TIME_FORMAT = "%Y-%m-%dT%H:%M:%SZ"
-    TIME_FORMAT_2 = "%Y-%m-%dT%H:%M:%S.%fZ"
-    TIME_FORMAT_WITH_FRAGMENT = re.compile(r'^(\d{4,4}-\d{2,2}-\d{2,2}T\d{2,2}:\d{2,2}:\d{2,2})(\.\d*)?Z?$')
-
     @staticmethod
     def escape_url(url, lowercase_urlencoding=False):
         """
@@ -377,49 +372,41 @@ def generate_unique_id():
     def parse_time_to_SAML(time):
         r"""
         Converts a UNIX timestamp to SAML2 timestamp on the form
-        yyyy-mm-ddThh:mm:ss(\.s+)?Z.
+        yyyy-mm-ddThh:mm:ss.
+
+        > All SAML time values have the type "xs:dateTime",
+        > which is built in to the W3C XML Schema Datatypes specification,
+        > and MUST be expressed in UTC form, with no time zone component.
 
         :param time: The time we should convert (DateTime).
         :type: string
 
         :return: SAML2 timestamp.
         :rtype: string
         """
-        data = datetime.utcfromtimestamp(float(time))
-        return data.strftime(OneLogin_Saml2_Utils.TIME_FORMAT)
+        return datetime.utcfromtimestamp(float(time)).isoformat(timespec="seconds")
 
     @staticmethod
     def parse_SAML_to_time(timestr):
         r"""
-        Converts a SAML2 timestamp on the form yyyy-mm-ddThh:mm:ss(\.s+)?Z
-        to a UNIX timestamp. The sub-second part is ignored.
+        Converts a SAML2 timestamp to a UNIX timestamp.
+        The sub-second part is truncated.
 
         :param timestr: The time we should convert (SAML Timestamp).
         :type: string
 
         :return: Converted to a unix timestamp.
         :rtype: int
         """
-        try:
-            data = datetime.strptime(timestr, OneLogin_Saml2_Utils.TIME_FORMAT)
-        except ValueError:
-            try:
-                data = datetime.strptime(timestr, OneLogin_Saml2_Utils.TIME_FORMAT_2)
-            except ValueError:
-                elem = OneLogin_Saml2_Utils.TIME_FORMAT_WITH_FRAGMENT.match(timestr)
-                if not elem:
-                    raise Exception("time data %s does not match format %s" % (timestr, r'yyyy-mm-ddThh:mm:ss(\.s+)?Z'))
-                data = datetime.strptime(elem.groups()[0] + "Z", OneLogin_Saml2_Utils.TIME_FORMAT)
-
-        return calendar.timegm(data.utctimetuple())
+        return int(datetime.fromisoformat(timestr).timestamp())
 
     @staticmethod
     def now():
         """
         :return: unix timestamp of actual time.
         :rtype: int
         """
-        return calendar.timegm(datetime.utcnow().utctimetuple())
+        return int(datetime.now().timestamp())
 
     @staticmethod
     def parse_duration(duration, timestamp=None):
@@ -444,7 +431,7 @@ def parse_duration(duration, timestamp=None):
             data = datetime.utcnow() + timedelta
         else:
             data = datetime.utcfromtimestamp(timestamp) + timedelta
-        return calendar.timegm(data.utctimetuple())
+        return int(data.timestamp())
 
     @staticmethod
     def get_expire_time(cache_duration=None, valid_until=None):