Refactor time code, add tests, fix bug when parsing absolute timestamps that omit seconds (#745)

* Add time module utils.

* Add time helpers to ACME backend.

* Add changelog fragment.

* ACME timestamp parser: do not choke on nanoseconds.

plugins/module_utils/acme/backend_cryptography.py

@@ -11,6 +11,7 @@ __metaclass__ = type
 
 import base64
 import binascii
+import datetime
 import os
 import traceback
 
@@ -21,6 +22,7 @@ from ansible_collections.community.crypto.plugins.module_utils.version import Lo
 from ansible_collections.community.crypto.plugins.module_utils.acme.backends import (
     CertificateInformation,
     CryptoBackend,
+    _parse_acme_timestamp,
 )
 
 from ansible_collections.community.crypto.plugins.module_utils.acme.certificates import (
@@ -41,12 +43,6 @@ from ansible_collections.community.crypto.plugins.module_utils.crypto.math impor
     convert_int_to_hex,
 )
 
-from ansible_collections.community.crypto.plugins.module_utils.crypto.support import (
-    get_now_datetime,
-    ensure_utc_timezone,
-    parse_name_field,
-)
-
 from ansible_collections.community.crypto.plugins.module_utils.crypto.cryptography_support import (
     CRYPTOGRAPHY_TIMEZONE,
     cryptography_name_to_oid,
@@ -59,6 +55,18 @@ from ansible_collections.community.crypto.plugins.module_utils.crypto.pem import
     extract_first_pem,
 )
 
+from ansible_collections.community.crypto.plugins.module_utils.crypto.support import (
+    parse_name_field,
+)
+
+from ansible_collections.community.crypto.plugins.module_utils.time import (
+    ensure_utc_timezone,
+    from_epoch_seconds,
+    get_epoch_seconds,
+    get_now_datetime,
+    UTC,
+)
+
 CRYPTOGRAPHY_MINIMAL_VERSION = '1.5'
 
 CRYPTOGRAPHY_ERROR = None
@@ -173,6 +181,26 @@ class CryptographyBackend(CryptoBackend):
     def __init__(self, module):
         super(CryptographyBackend, self).__init__(module)
 
+    def get_now(self):
+        return get_now_datetime(with_timezone=CRYPTOGRAPHY_TIMEZONE)
+
+    def parse_acme_timestamp(self, timestamp_str):
+        return _parse_acme_timestamp(timestamp_str, with_timezone=CRYPTOGRAPHY_TIMEZONE)
+
+    def interpolate_timestamp(self, timestamp_start, timestamp_end, percentage):
+        start = get_epoch_seconds(timestamp_start)
+        end = get_epoch_seconds(timestamp_end)
+        return from_epoch_seconds(start + percentage * (end - start), with_timezone=CRYPTOGRAPHY_TIMEZONE)
+
+    def get_utc_datetime(self, *args, **kwargs):
+        kwargs_ext = dict(kwargs)
+        if CRYPTOGRAPHY_TIMEZONE and ('tzinfo' not in kwargs_ext and len(args) < 8):
+            kwargs_ext['tzinfo'] = UTC
+        result = datetime.datetime(*args, **kwargs_ext)
+        if CRYPTOGRAPHY_TIMEZONE and ('tzinfo' in kwargs or len(args) >= 8):
+            result = ensure_utc_timezone(result)
+        return result
+
     def parse_key(self, key_file=None, key_content=None, passphrase=None):
         '''
         Parses an RSA or Elliptic Curve key file in PEM format and returns key_data.
@@ -379,7 +407,7 @@ class CryptographyBackend(CryptoBackend):
             raise BackendException('Cannot parse certificate {0}: {1}'.format(cert_filename, e))
 
         if now is None:
-            now = get_now_datetime(with_timezone=CRYPTOGRAPHY_TIMEZONE)
+            now = self.get_now()
         elif CRYPTOGRAPHY_TIMEZONE:
             now = ensure_utc_timezone(now)
         return (get_not_valid_after(cert) - now).days

plugins/module_utils/acme/backends.py

@@ -11,6 +11,8 @@ __metaclass__ = type
 
 from collections import namedtuple
 import abc
+import datetime
+import re
 
 from ansible.module_utils import six
 
@@ -18,6 +20,14 @@ from ansible_collections.community.crypto.plugins.module_utils.acme.errors impor
     BackendException,
 )
 
+from ansible_collections.community.crypto.plugins.module_utils.time import (
+    ensure_utc_timezone,
+    from_epoch_seconds,
+    get_epoch_seconds,
+    get_now_datetime,
+    remove_timezone,
+)
+
 
 CertificateInformation = namedtuple(
     'CertificateInformation',
@@ -31,11 +41,65 @@ CertificateInformation = namedtuple(
 )
 
 
+_FRACTIONAL_MATCHER = re.compile(r'^(\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2})(|\.\d+)(Z|[+-]\d{2}:?\d{2}.*)$')
+
+
+def _reduce_fractional_digits(timestamp_str):
+    """
+    Given a RFC 3339 timestamp that includes too many digits for the fractional seconds part, reduces these to at most 6.
+    """
+    # RFC 3339 (https://www.rfc-editor.org/info/rfc3339)
+    m = _FRACTIONAL_MATCHER.match(timestamp_str)
+    if not m:
+        raise BackendException('Cannot parse ISO 8601 timestamp {0!r}'.format(timestamp_str))
+    timestamp, fractional, timezone = m.groups()
+    if len(fractional) > 7:
+        # Python does not support anything smaller than microseconds
+        # (Golang supports nanoseconds, Boulder often emits more fractional digits, which Python chokes on)
+        fractional = fractional[:7]
+    return '%s%s%s' % (timestamp, fractional, timezone)
+
+
+def _parse_acme_timestamp(timestamp_str, with_timezone):
+    """
+    Parses a RFC 3339 timestamp.
+    """
+    # RFC 3339 (https://www.rfc-editor.org/info/rfc3339)
+    timestamp_str = _reduce_fractional_digits(timestamp_str)
+    for format in ('%Y-%m-%dT%H:%M:%SZ', '%Y-%m-%dT%H:%M:%S.%fZ', '%Y-%m-%dT%H:%M:%S%z', '%Y-%m-%dT%H:%M:%S.%f%z'):
+        # Note that %z won't work with Python 2... https://stackoverflow.com/a/27829491
+        try:
+            result = datetime.datetime.strptime(timestamp_str, format)
+        except ValueError:
+            pass
+        else:
+            return ensure_utc_timezone(result) if with_timezone else remove_timezone(result)
+    raise BackendException('Cannot parse ISO 8601 timestamp {0!r}'.format(timestamp_str))
+
+
 @six.add_metaclass(abc.ABCMeta)
 class CryptoBackend(object):
     def __init__(self, module):
         self.module = module
 
+    def get_now(self):
+        return get_now_datetime(with_timezone=False)
+
+    def parse_acme_timestamp(self, timestamp_str):
+        # RFC 3339 (https://www.rfc-editor.org/info/rfc3339)
+        return _parse_acme_timestamp(timestamp_str, with_timezone=False)
+
+    def interpolate_timestamp(self, timestamp_start, timestamp_end, percentage):
+        start = get_epoch_seconds(timestamp_start)
+        end = get_epoch_seconds(timestamp_end)
+        return from_epoch_seconds(start + percentage * (end - start), with_timezone=False)
+
+    def get_utc_datetime(self, *args, **kwargs):
+        result = datetime.datetime(*args, **kwargs)
+        if 'tzinfo' in kwargs or len(args) >= 8:
+            result = remove_timezone(result)
+        return result
+
     @abc.abstractmethod
     def parse_key(self, key_file=None, key_content=None, passphrase=None):
         '''

plugins/module_utils/acme/utils.py

@@ -22,7 +22,7 @@ from ansible_collections.community.crypto.plugins.module_utils.acme.errors impor
 
 from ansible_collections.community.crypto.plugins.module_utils.crypto.math import convert_int_to_bytes
 
-from ansible_collections.community.crypto.plugins.module_utils.crypto.support import get_now_datetime
+from ansible_collections.community.crypto.plugins.module_utils.time import get_now_datetime
 
 
 def nopad_b64(data):