Fix HTTP_USER_AGENT latin1 characters

common/djangoapps/track/backends/tests/test_logger.py

+# -*- coding: utf-8 -*-
+"""Tests for Event tracker backend."""
 from __future__ import absolute_import
 
 import json

common/djangoapps/track/middleware.py

@@ -142,6 +142,10 @@ class TrackMiddleware(object):
         for header_name, context_key in META_KEY_TO_CONTEXT_KEY.iteritems():
             context[context_key] = request.META.get(header_name, '')
 
+        # HTTP_USER_AGENT user might can contain the information that include latin1 characters
+        # decoding this using latin1 scheme will prevent to raise UnicodeDecodeError when using
+        # json.dumps for tracking purpose.
+        context['agent'] = context['agent'].decode('latin1')
         # Google Analytics uses the clientId to keep track of unique visitors. A GA cookie looks like
         # this: _ga=GA1.2.1033501218.1368477899. The clientId is this part: 1033501218.1368477899.
         google_analytics_cookie = request.COOKIES.get('_ga')

common/djangoapps/track/tests/test_middleware.py

+# -*- coding: utf-8 -*-
+"""Tests for tracking middleware."""
 from mock import patch
 from mock import sentinel
 
@@ -27,6 +29,18 @@ class TrackMiddlewareTestCase(TestCase):
         self.track_middleware.process_request(request)
         self.assertTrue(self.mock_server_track.called)
 
+    def test_request_with_latin1_characters(self):
+        """
+        When HTTP_USER_AGENT in request.META contains latin1 characters.
+        """
+        request = self.request_factory.get('/somewhere')
+        request.META['HTTP_USER_AGENT'] = 'test latin1 \xd3 \xe9 \xf1'  # pylint: disable=no-member
+
+        context = self.get_context_for_request(request)
+        # The bytes in the string on the right are utf8 encoded in the source file, so we decode them to construct
+        # a valid unicode string.
+        self.assertEqual(context['agent'], 'test latin1 Ó é ñ'.decode('utf8'))
+
     def test_default_filters_do_not_render_view(self):
         for url in ['/event', '/event/1', '/login', '/heartbeat']:
             request = self.request_factory.get(url)

common/djangoapps/track/views/__init__.py

@@ -105,7 +105,7 @@ def server_track(request, event_type, event, page=None):
         "event_source": "server",
         "event_type": event_type,
         "event": event,
-        "agent": _get_request_header(request, 'HTTP_USER_AGENT'),
+        "agent": _get_request_header(request, 'HTTP_USER_AGENT').decode('latin1'),
         "page": page,
         "time": datetime.datetime.utcnow(),
         "host": _get_request_header(request, 'SERVER_NAME'),

lms/djangoapps/instructor_task/api_helper.py

@@ -88,7 +88,7 @@ def _get_xmodule_instance_args(request, task_id):
     """
     request_info = {'username': request.user.username,
                     'ip': request.META['REMOTE_ADDR'],
-                    'agent': request.META.get('HTTP_USER_AGENT', ''),
+                    'agent': request.META.get('HTTP_USER_AGENT', '').decode('latin1'),
                     'host': request.META['SERVER_NAME'],
                     }