From 8c38b6941878d846d9bb69bf4018d5e5490cb30b Mon Sep 17 00:00:00 2001
From: Seb Bacon <seb.bacon@gmail.com>
Date: Tue, 1 Nov 2016 18:24:51 +0000
Subject: [PATCH] Compatibility with earlier Python 2.7 versions

Compatibility with Python 2.7 versions older than 2.7.7

* Use Django's constant_time_compare method
* Include sparkpost in test requirements
* Don't use non-public `EnvironmentVarGuard` in tests

Fixes #41

(cherry picked from commit f0589e333834990e591dfd16a5b45e7c8f414c2f)
---
 anymail/webhooks/mailgun.py     |  3 ++-
 anymail/webhooks/mandrill.py    |  3 ++-
 setup.py                        |  2 +-
 tests/test_sparkpost_backend.py | 13 ++++---------
 4 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/anymail/webhooks/mailgun.py b/anymail/webhooks/mailgun.py
index ad110f85..bb0a785b 100644
--- a/anymail/webhooks/mailgun.py
+++ b/anymail/webhooks/mailgun.py
@@ -3,6 +3,7 @@
 
 import hashlib
 import hmac
+from django.utils.crypto import constant_time_compare
 from django.utils.timezone import utc
 
 from .base import AnymailBaseWebhookView
@@ -34,7 +35,7 @@ def validate_request(self, request):
             raise AnymailWebhookValidationFailure("Mailgun webhook called without required security fields")
         expected_signature = hmac.new(key=self.api_key, msg='{}{}'.format(timestamp, token).encode('ascii'),
                                       digestmod=hashlib.sha256).hexdigest()
-        if not hmac.compare_digest(signature, expected_signature):
+        if not constant_time_compare(signature, expected_signature):
             raise AnymailWebhookValidationFailure("Mailgun webhook called with incorrect signature")
 
     def parse_events(self, request):
diff --git a/anymail/webhooks/mandrill.py b/anymail/webhooks/mandrill.py
index 3e6a2295..b1d0c639 100644
--- a/anymail/webhooks/mandrill.py
+++ b/anymail/webhooks/mandrill.py
@@ -4,6 +4,7 @@
 import hashlib
 import hmac
 from base64 import b64encode
+from django.utils.crypto import constant_time_compare
 from django.utils.timezone import utc
 
 from .base import AnymailBaseWebhookView
@@ -44,7 +45,7 @@ def validate_request(self, request):
 
         expected_signature = b64encode(hmac.new(key=self.webhook_key, msg=signed_data.encode('utf-8'),
                                                 digestmod=hashlib.sha1).digest())
-        if not hmac.compare_digest(signature, expected_signature):
+        if not constant_time_compare(signature, expected_signature):
             raise AnymailWebhookValidationFailure("Mandrill webhook called with incorrect signature")
 
 
diff --git a/setup.py b/setup.py
index dfcdc430..f21631db 100644
--- a/setup.py
+++ b/setup.py
@@ -47,7 +47,7 @@ def long_description_from_readme(rst):
     },
     include_package_data=True,
     test_suite="runtests.runtests",
-    tests_require=["mock"],
+    tests_require=["mock", "sparkpost"],
     classifiers=[
         "Development Status :: 2 - Pre-Alpha",
         "Programming Language :: Python",
diff --git a/tests/test_sparkpost_backend.py b/tests/test_sparkpost_backend.py
index 624b7ee5..8f108a98 100644
--- a/tests/test_sparkpost_backend.py
+++ b/tests/test_sparkpost_backend.py
@@ -3,6 +3,7 @@
 from datetime import datetime, date
 from email.mime.base import MIMEBase
 from email.mime.image import MIMEImage
+import os
 
 import requests
 import six
@@ -17,13 +18,6 @@
                                 AnymailConfigurationError)
 from anymail.message import attach_inline_image_file
 
-try:
-    # noinspection PyUnresolvedReferences
-    from test.support import EnvironmentVarGuard  # python3
-except ImportError:
-    # noinspection PyUnresolvedReferences
-    from test.test_support import EnvironmentVarGuard  # python2
-
 from .utils import AnymailTestMixin, decode_att, SAMPLE_IMAGE_FILENAME, sample_image_path, sample_image_content
 
 
@@ -579,8 +573,9 @@ def test_missing_api_key(self):
 
     def test_api_key_in_env(self):
         """SparkPost package allows API key in env var; make sure Anymail works with that"""
-        with EnvironmentVarGuard() as env:
-            env['SPARKPOST_API_KEY'] = 'key_from_environment'
+        with patch.dict(
+                os.environ,
+                {'SPARKPOST_API_KEY': 'key_from_environment'}):
             conn = mail.get_connection()
             # Poke into implementation details to verify:
             self.assertIsNone(conn.api_key)  # Anymail prop