Set a request id on all requests (#6922)

The request id is extracted from an header set using the
REQUEST_ID_HEADER setting or generated using the default Python random
number generator.

src/authentic2/middleware.py

@@ -1,5 +1,7 @@
 import logging
 import datetime
+import random
+import struct
 try:
     import threading
 except ImportError:
@@ -108,6 +110,18 @@ class OpenedSessionCookieMiddleware(object):
                     domain=app_settings.A2_OPENED_SESSION_COOKIE_DOMAIN)
         return response
 
+class RequestIdMiddleware(object):
+    def process_request(self, request):
+        if not hasattr(request, 'request_id'):
+            request_id_header = getattr(settings, 'REQUEST_ID_HEADER', None)
+            if request_id_header and request.META.get(request_id_header):
+                request.request_id = request.META[request_id_header]
+            else:
+                # Use Mersennes Twister rng, no need for a cryptographic grade
+                # rng in this case
+                random_id = random.getrandbits(32)
+                request.request_id = struct.pack('I', random_id).encode('hex')
+
 class StoreRequestMiddleware(object):
     collection = {}
 

src/authentic2/settings.py

@@ -54,6 +54,7 @@ TEMPLATE_CONTEXT_PROCESSORS = (
 )
 
 MIDDLEWARE_CLASSES = (
+    'authentic2.middleware.RequestIdMiddleware',
     'authentic2.middleware.LoggingCollectorMiddleware',
     'django.middleware.common.CommonMiddleware',
     'django.middleware.http.ConditionalGetMiddleware',