Merge pull request #15510 from edx/ri/EDUCATOR-810-unicode-decode-error

EDUCATOR-810 fix UnicodeDecodeError

cms/envs/common.py

@@ -932,6 +932,9 @@ INSTALLED_APPS = (
     # Site configuration for theming and behavioral modification
     'openedx.core.djangoapps.site_configuration',
 
+    # Ability to detect and special-case crawler behavior
+    'openedx.core.djangoapps.crawlers',
+
     # comment common
     'django_comment_common',
 

openedx/core/djangoapps/crawlers/models.py

@@ -2,6 +2,7 @@
 This module handles the detection of crawlers, so that we can handle them
 appropriately in other parts of the code.
 """
+import six
 from config_models.models import ConfigurationModel
 from django.db import models
 
@@ -39,6 +40,14 @@ class CrawlersConfig(ConfigurationModel):
         if (not req_user_agent) or (not crawler_agents):
             return False
 
+        # The crawler_agents list we pull from our model always has unicode objects, but the
+        # req_user_agent we get from HTTP headers ultimately comes to us via WSGI. That
+        # value is an ISO-8859-1 encoded byte string in Python 2.7 (and in the HTTP spec), but
+        # it will be a unicode str when we move to Python 3.x. This code should work under
+        # either version.
+        if isinstance(req_user_agent, six.binary_type):
+            crawler_agents = [crawler_agent.encode('iso-8859-1') for crawler_agent in crawler_agents]
+
         # We perform prefix matching of the crawler agent here so that we don't
         # have to worry about version bumps.
         return any(

openedx/core/djangoapps/crawlers/tests/test_models.py

@@ -0,0 +1,41 @@
+# -*- coding: utf-8 -*-
+"""
+Tests that the request came from a crawler or not.
+"""
+import ddt
+from django.test import TestCase
+from django.http import HttpRequest
+from ..models import CrawlersConfig
+
+
+@ddt.ddt
+class CrawlersConfigTest(TestCase):
+
+    def setUp(self):
+        super(CrawlersConfigTest, self).setUp()
+        CrawlersConfig(known_user_agents='edX-downloader,crawler_foo', enabled=True).save()
+
+    @ddt.data(
+        "Mozilla/5.0 (Linux; Android 5.1; Nexus 5 Build/LMY47I; wv) AppleWebKit/537.36 (KHTML, like Gecko) "
+        "Version/4.0 Chrome/47.0.2526.100 Mobile Safari/537.36 edX/org.edx.mobile/2.0.0",
+        "Le Héros des Deux Mondes",
+    )
+    def test_req_user_agent_is_not_crawler(self, req_user_agent):
+        """
+        verify that the request did not come from a crawler.
+        """
+        fake_request = HttpRequest()
+        fake_request.META['HTTP_USER_AGENT'] = req_user_agent
+        self.assertFalse(CrawlersConfig.is_crawler(fake_request))
+
+    @ddt.data(
+        u"edX-downloader",
+        "crawler_foo".encode("utf-8")
+    )
+    def test_req_user_agent_is_crawler(self, req_user_agent):
+        """
+        verify that the request came from a crawler.
+        """
+        fake_request = HttpRequest()
+        fake_request.META['HTTP_USER_AGENT'] = req_user_agent
+        self.assertTrue(CrawlersConfig.is_crawler(fake_request))