S3: LastModified-date should always be in English (#7254)

moto/core/utils.py

@@ -170,10 +170,36 @@ def iso_8601_datetime_without_milliseconds_s3(
 
 
 RFC1123 = "%a, %d %b %Y %H:%M:%S GMT"
+EN_WEEKDAYS = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
+EN_MONTHS = [
+    "Jan",
+    "Feb",
+    "Mar",
+    "Apr",
+    "May",
+    "Jun",
+    "Jul",
+    "Aug",
+    "Sep",
+    "Oct",
+    "Nov",
+    "Dec",
+]
 
 
 def rfc_1123_datetime(src: datetime.datetime) -> str:
-    return src.strftime(RFC1123)
+    """
+    Returns the datetime in the RFC-1123 format
+    Names of weekdays/months are in English
+    """
+    # strftime uses the current locale to translate values
+    # So weekday/month values may not be in English
+    # For our usecase, we need these values to always be in English, otherwise botocore is unable to parse it
+    # Having a hardcoded list ensures this always works, even if the user does not have an English locale installed
+    eng_weekday = EN_WEEKDAYS[src.isoweekday() - 1]
+    eng_month = EN_MONTHS[src.month - 1]
+    non_locallized_rfc1123 = RFC1123.replace("%a", "{}").replace("%b", "{}")
+    return src.strftime(non_locallized_rfc1123).format(eng_weekday, eng_month)
 
 
 def str_to_rfc_1123_datetime(value: str) -> datetime.datetime:

tests/test_core/test_utils.py

@@ -1,3 +1,5 @@
+import datetime
+
 import pytest
 from freezegun import freeze_time
 
@@ -5,6 +7,8 @@ from moto.core.utils import (
     camelcase_to_pascal,
     camelcase_to_underscores,
     pascal_to_camelcase,
+    rfc_1123_datetime,
+    str_to_rfc_1123_datetime,
     underscores_to_camelcase,
     unix_time,
 )
@@ -50,3 +54,10 @@ def test_camelcase_to_pascal(_input: str, expected: str) -> None:
 @freeze_time("2015-01-01 12:00:00")
 def test_unix_time() -> None:  # type: ignore[misc]
     assert unix_time() == 1420113600.0
+
+
+def test_rfc1123_dates() -> None:
+    with freeze_time("2012-03-04 05:00:05"):
+        x = rfc_1123_datetime(datetime.datetime.now())
+        assert x == "Sun, 04 Mar 2012 05:00:05 GMT"
+        assert str_to_rfc_1123_datetime(x) == datetime.datetime.now()

tests/test_s3/test_s3_locales.py

@@ -0,0 +1,30 @@
+from datetime import datetime
+from unittest import SkipTest
+
+import boto3
+from freezegun import freeze_time
+
+from moto import mock_s3, settings
+
+
+@mock_s3
+def test_rfc_returns_valid_date_for_every_possible_weekday_and_month():
+    if not settings.TEST_DECORATOR_MODE:
+        raise SkipTest("Freezing time only possible in DecoratorMode")
+    client = boto3.client("s3", region_name="us-east-1")
+    client.create_bucket(Bucket="bucket_")
+    for weekday in range(1, 8):
+        with freeze_time(f"2023-02-{weekday} 12:00:00"):
+            client.put_object(Bucket="bucket_", Key="test.txt", Body=b"test")
+            obj = client.get_object(Bucket="bucket_", Key="test.txt")
+            assert obj["LastModified"].replace(tzinfo=None) == datetime.now()
+            # If we get here, the LastModified date will have been successfully parsed
+            # Regardless of which weekday it is
+
+    for month in range(1, 13):
+        with freeze_time(f"2023-{month}-02 12:00:00"):
+            client.put_object(Bucket="bucket_", Key="test.txt", Body=b"test")
+            obj = client.get_object(Bucket="bucket_", Key="test.txt")
+            assert obj["LastModified"].replace(tzinfo=None) == datetime.now()
+            # If we get here, the LastModified date will have been successfully parsed
+            # Regardless of which month it is