handle Y2038 in timestamp to datetime conversions

According to datetime.utcfromtimestamp() method documentation[1],
this and similar methods fail for dates past 2038 and can be replaced by
the following expression on the POSIX compliant systems:

  datetime(1970, 1, 1, tzinfo=timezone.utc) + timedelta(seconds=timestamp)

Make sure to use a method that at least allows to import the timestamps
properly to datetime objects on 32-bit platforms.

[1] https://docs.python.org/3/library/datetime.html#datetime.datetime.utcfromtimestamp

Fixes: https://pagure.io/freeipa/issue/8378

Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>
Reviewed-By: Christian Heimes <cheimes@redhat.com>

ipapython/cookie.py

@@ -22,6 +22,7 @@ import datetime
 import email.utils
 from calendar import timegm
 from urllib.parse import urlparse
+from ipapython.ipautil import datetime_from_utctimestamp
 
 
 '''
@@ -184,7 +185,7 @@ class Cookie:
         # use the RFC 1123 parsing function which uses only English
 
         try:
-            dt = datetime.datetime(*email.utils.parsedate(s)[0:6])
+            dt = email.utils.parsedate_to_datetime(s)
         except Exception as e:
             raise ValueError("unable to parse expires datetime '%s': %s" % (s, e))
 
@@ -390,7 +391,7 @@ class Cookie:
         elif isinstance(value, datetime.datetime):
             self._timestamp = value
         elif isinstance(value, (int, float)):
-            self._timestamp = datetime.datetime.utcfromtimestamp(value)
+            self._timestamp = datetime_from_utctimestamp(value, units=1)
         elif isinstance(value, str):
             self._timestamp = Cookie.parse_datetime(value)
         else:
@@ -415,8 +416,10 @@ class Cookie:
             self._expires = None
         elif isinstance(value, datetime.datetime):
             self._expires = value
+            if self._expires.tzinfo is None:
+                self._expires.replace(tzinfo=datetime.timezone.utc)
         elif isinstance(value, (int, float)):
-            self._expires = datetime.datetime.utcfromtimestamp(value)
+            self._expires = datetime_from_utctimestamp(value, units=1)
         elif isinstance(value, str):
             self._expires = Cookie.parse_datetime(value)
         else:

ipapython/ipautil.py

@@ -1647,3 +1647,27 @@ def rmtree(path):
             shutil.rmtree(path)
     except Exception as e:
         logger.error('Error removing %s: %s', path, str(e))
+
+
+def datetime_from_utctimestamp(t, units=1):
+    """
+    Convert a timestamp or a time.struct_time to a datetime.datetime
+    object down to seconds, with UTC timezone
+
+    The conversion is safe for year 2038 problem
+
+    :param t: int or float timestamp in (milli)seconds since UNIX epoch
+              or time.struct_time
+    :param units: normalizing factor for the timestamp
+                  (1 for seconds, 1000 for milliseconds)
+                  defaults to 1
+    :return: datetime.datetime object in UTC timezone
+    """
+    if isinstance(t, time.struct_time):
+        v = int(time.mktime(t))
+    elif isinstance(t, (float, int)):
+        v = int(t)
+    else:
+        raise TypeError(t)
+    epoch = datetime.datetime(1970, 1, 1, tzinfo=datetime.timezone.utc)
+    return epoch + datetime.timedelta(seconds=v // units)

ipaserver/dnssec/_ods21.py

@@ -2,7 +2,6 @@
 # Copyright (C) 2020  FreeIPA Contributors see COPYING for license
 #
 
-from datetime import datetime
 import os
 
 from ipaserver.dnssec._odsbase import AbstractODSDBConnection
@@ -39,7 +38,10 @@ class ODSDBConnection(AbstractODSDBConnection):
         for row in cur:
             key = dict()
             key['HSMkey_id'] = row['locator']
-            key['generate'] = str(datetime.fromtimestamp(row['inception']))
+            key['generate'] = ipautil.datetime_from_utctimestamp(
+                row['inception'],
+                units=1).replace(tzinfo=None).isoformat(
+                    sep=' ', timespec='seconds')
             key['algorithm'] = row['algorithm']
             key['publish'] = key['generate']
             key['active'] = None

ipaserver/plugins/cert.py

@@ -52,6 +52,7 @@ from ipalib.request import context
 from ipalib import output
 from ipapython import dnsutil, kerberos
 from ipapython.dn import DN
+from ipapython.ipautil import datetime_from_utctimestamp
 from ipaserver.plugins.service import normalize_principal, validate_realm
 from ipaserver.masters import (
     ENABLED_SERVICE, CONFIGURED_SERVICE, is_service_enabled
@@ -254,8 +255,9 @@ def normalize_pkidate(value):
 
 
 def convert_pkidatetime(value):
-    value = datetime.datetime.fromtimestamp(int(value) // 1000)
-    return x509.format_datetime(value)
+    if isinstance(value, str):
+        value = int(value)
+    return x509.format_datetime(datetime_from_utctimestamp(value, units=1000))
 
 
 def normalize_serial_number(num):

ipaserver/plugins/dogtag.py

@@ -241,7 +241,6 @@ digits and nothing else follows.
 
 from __future__ import absolute_import
 
-import datetime
 import json
 import logging
 
@@ -651,12 +650,14 @@ def parse_check_request_result_xml(doc):
 
     updated_on = doc.xpath('//xml/header/updatedOn[1]')
     if len(updated_on) == 1:
-        updated_on = datetime.datetime.utcfromtimestamp(int(updated_on[0].text))
+        updated_on = ipautil.datetime_from_utctimestamp(
+            int(updated_on[0].text), units=1)
         response['updated_on'] = updated_on
 
     created_on = doc.xpath('//xml/header/createdOn[1]')
     if len(created_on) == 1:
-        created_on = datetime.datetime.utcfromtimestamp(int(created_on[0].text))
+        created_on = ipautil.datetime_from_utctimestamp(
+            int(created_on[0].text), units=1)
         response['created_on'] = created_on
 
     request_notes = doc.xpath('//xml/header/requestNotes[1]')

ipatests/test_ipapython/test_cookie.py

@@ -19,9 +19,8 @@
 
 import datetime
 import email.utils
-import calendar
 from ipapython.cookie import Cookie
-
+from ipapython.ipautil import datetime_from_utctimestamp
 import pytest
 
 pytestmark = pytest.mark.tier0
@@ -148,17 +147,21 @@ class TestExpires:
     @pytest.fixture(autouse=True)
     def expires_setup(self):
         # Force microseconds to zero because cookie timestamps only have second resolution
-        self.now = datetime.datetime.utcnow().replace(microsecond=0)
-        self.now_timestamp = calendar.timegm(self.now.utctimetuple())
+        self.now = datetime.datetime.now(
+            tz=datetime.timezone.utc).replace(microsecond=0)
+        self.now_timestamp = datetime_from_utctimestamp(
+            self.now.utctimetuple(), units=1).timestamp()
         self.now_string = email.utils.formatdate(self.now_timestamp, usegmt=True)
 
         self.max_age = 3600     # 1 hour
         self.age_expiration = self.now + datetime.timedelta(seconds=self.max_age)
-        self.age_timestamp = calendar.timegm(self.age_expiration.utctimetuple())
+        self.age_timestamp = datetime_from_utctimestamp(
+            self.age_expiration.utctimetuple(), units=1).timestamp()
         self.age_string = email.utils.formatdate(self.age_timestamp, usegmt=True)
 
         self.expires = self.now + datetime.timedelta(days=1) # 1 day
-        self.expires_timestamp = calendar.timegm(self.expires.utctimetuple())
+        self.expires_timestamp = datetime_from_utctimestamp(
+            self.expires.utctimetuple(), units=1).timestamp()
         self.expires_string = email.utils.formatdate(self.expires_timestamp, usegmt=True)
 
     def test_expires(self):
@@ -327,7 +330,8 @@ class TestAttributes:
         assert cookie.max_age is None
 
         cookie.expires = 'Sun, 06 Nov 1994 08:49:37 GMT'
-        assert cookie.expires == datetime.datetime(1994, 11, 6, 8, 49, 37)
+        assert cookie.expires == datetime.datetime(
+            1994, 11, 6, 8, 49, 37, tzinfo=datetime.timezone.utc)
         cookie.expires = None
         assert cookie.expires is None
 
@@ -433,17 +437,21 @@ class TestNormalization:
     @pytest.fixture(autouse=True)
     def normalization_setup(self):
         # Force microseconds to zero because cookie timestamps only have second resolution
-        self.now = datetime.datetime.utcnow().replace(microsecond=0)
-        self.now_timestamp = calendar.timegm(self.now.utctimetuple())
+        self.now = datetime.datetime.now(
+            tz=datetime.timezone.utc).replace(microsecond=0)
+        self.now_timestamp = datetime_from_utctimestamp(
+            self.now.utctimetuple(), units=1).timestamp()
         self.now_string = email.utils.formatdate(self.now_timestamp, usegmt=True)
 
         self.max_age = 3600     # 1 hour
         self.age_expiration = self.now + datetime.timedelta(seconds=self.max_age)
-        self.age_timestamp = calendar.timegm(self.age_expiration.utctimetuple())
+        self.age_timestamp = datetime_from_utctimestamp(
+            self.age_expiration.utctimetuple(), units=1).timestamp()
         self.age_string = email.utils.formatdate(self.age_timestamp, usegmt=True)
 
         self.expires = self.now + datetime.timedelta(days=1) # 1 day
-        self.expires_timestamp = calendar.timegm(self.expires.utctimetuple())
+        self.expires_timestamp = datetime_from_utctimestamp(
+            self.expires.utctimetuple(), units=1).timestamp()
         self.expires_string = email.utils.formatdate(self.expires_timestamp, usegmt=True)
 
     def test_path_normalization(self):