fix some cmient-side caching issues (see #316)

burpui/api/__init__.py

@@ -13,7 +13,7 @@ import sys
 import uuid
 import hashlib
 
-from flask import Blueprint, Response, request, current_app, session, abort
+from flask import Blueprint, Response, request, current_app, session, abort, g
 from flask_restplus import Api as ApiPlus
 from flask_login import current_user
 from importlib import import_module
@@ -31,7 +31,8 @@ EXEMPT_METHODS = set(['OPTIONS'])
 
 
 def force_refresh():
-    return request.headers.get('X-No-Cache', False) is not False
+    return request.headers.get('X-No-Cache', False) is not False or \
+        getattr(g, 'DONOTCACHE', False)
 
 
 def cache_key():

burpui/api/clients.py

@@ -16,7 +16,7 @@ from ..exceptions import BUIserverException
 from ..decorators import browser_cache
 from ..filter import mask
 
-from flask import current_app
+from flask import current_app, g
 from flask_login import current_user
 
 bui = current_app  # type: BUIServer
@@ -505,6 +505,8 @@ class ClientsStats(Resource):
                 self.abort(500, str(exp))
             tmp_client['labels'] = labels
             ret.append(tmp_client)
+            if tmp_client['state'] != 'idle':
+                g.DONOTCACHE = True
 
         return ret
 

burpui/api/servers.py

@@ -9,7 +9,7 @@ from ..ext.cache import cache
 from ..decorators import browser_cache
 from ..exceptions import BUIserverException
 
-from flask import current_app
+from flask import current_app, g
 from flask_login import current_user
 
 bui = current_app  # type: BUIServer
@@ -76,6 +76,7 @@ class ServersStats(Resource):
                 alive = bui.client.servers[serv].ping()
             except BUIserverException:
                 alive = False
+                g.DONOTCACHE = True
 
             try:
                 clients = bui.client.servers[serv].get_all_clients(serv)

burpui/decorators.py

@@ -10,6 +10,7 @@
 import time
 import datetime
 
+from flask import g
 from functools import wraps
 
 
@@ -41,7 +42,10 @@ def browser_cache(expires=None):
 
             headers['Last-Modified'] = format_date_time(time.mktime(now.timetuple()))
 
-            if expires is None:
+            failure = code - 200 >= 100  # this is not a successful answer
+            do_not_cache = getattr(g, 'DONOTCACHE', False)
+
+            if expires is None or failure or do_not_cache:
                 headers['Cache-Control'] = 'no-store, no-cache, must-revalidate, post-check=0, pre-check=0, max-age=0'
             else:
                 headers['Cache-Control'] = 'private, max-age={}'.format(expires)