Anti-DDoS enhancements: Log to net log, UMA stats, improved policy.

net/url_request/url_request_throttler_manager.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_URL_REQUEST_URL_REQUEST_THROTTLER_MANAGER_H_
 #define NET_URL_REQUEST_URL_REQUEST_THROTTLER_MANAGER_H_
 #pragma once
 
 #include <map>
 #include <set>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/singleton.h"
 #include "base/threading/non_thread_safe.h"
 #include "googleurl/src/gurl.h"
 #include "net/base/net_api.h"
+#include "net/base/network_change_notifier.h"
 #include "net/url_request/url_request_throttler_entry.h"
 
 namespace net {
 
+class BoundNetLog;
+class NetLog;
+
 // Class that registers URL request throttler entries for URLs being accessed
 // in order to supervise traffic. URL requests for HTTP contents should
 // register their URLs in this manager on each request.
 //
 // URLRequestThrottlerManager maintains a map of URL IDs to URL request
 // throttler entries. It creates URL request throttler entries when new URLs
 // are registered, and does garbage collection from time to time in order to
 // clean out outdated entries. URL ID consists of lowercased scheme, host, port
 // and path. All URLs converted to the same ID will share the same entry.
 //
 // NOTE: All usage of this singleton object must be on the same thread,
 // although to allow it to be used as a singleton, construction and destruction
 // can occur on a separate thread.
-class NET_API URLRequestThrottlerManager

[wtc, 2011/05/25 23:12:06]

IMPORTANT: this is a merging error.  Please add back the
NET_API.

[Jói, 2011/05/26 14:53:42]

Fixed. Thanks for catching that.

-    : NON_EXPORTED_BASE(public base::NonThreadSafe) {
+class URLRequestThrottlerManager
+    : NON_EXPORTED_BASE(public base::NonThreadSafe),
+      public NetworkChangeNotifier::IPAddressObserver,
+      public NetworkChangeNotifier::OnlineStateObserver {
  public:
   static URLRequestThrottlerManager* GetInstance();
 
   // Must be called for every request, returns the URL request throttler entry
   // associated with the URL. The caller must inform this entry of some events.
   // Please refer to url_request_throttler_entry_interface.h for further
   // informations.
   scoped_refptr<URLRequestThrottlerEntryInterface> RegisterRequestUrl(
       const GURL& url);
 
@@ skipping 16 matching lines @@
   // Turns threading model verification on or off.  Any code that correctly
   // uses the network stack should preferably call this function to enable
   // verification of correct adherence to the network stack threading model.
   void set_enable_thread_checks(bool enable);
   bool enable_thread_checks() const;
 
   // Whether throttling is enabled or not.
   void set_enforce_throttling(bool enforce);
   bool enforce_throttling();
 
+  // Sets the NetLog instance to use.
+  void set_net_log(NetLog* net_log);
+  NetLog* net_log() const;
+
+  // IPAddressObserver interface.
+  virtual void OnIPAddressChanged() OVERRIDE;
+
+  // OnlineStateObserver interface.
+  virtual void OnOnlineStateChanged(bool online) OVERRIDE;
+
  protected:
   URLRequestThrottlerManager();
   ~URLRequestThrottlerManager();
 
   // Method that allows us to transform a URL into an ID that can be used in our
   // map. Resulting IDs will be lowercase and consist of the scheme, host, port
   // and path (without query string, fragment, etc.).
   // If the URL is invalid, the invalid spec will be returned, without any
   // transformation.
   std::string GetIdFromUrl(const GURL& url) const;
 
   // Method that ensures the map gets cleaned from time to time. The period at
   // which garbage collecting happens is adjustable with the
   // kRequestBetweenCollecting constant.
   void GarbageCollectEntriesIfNecessary();
 
   // Method that does the actual work of garbage collecting.
   void GarbageCollectEntries();
 
+  // When we switch from online to offline or change IP addresses, we
+  // clear all back-off history. This is a precaution in case the change in
+  // online state now lets us communicate without error with servers that
+  // we were previously getting 500 or 503 responses from (perhaps the
+  // responses are from a badly-written proxy that should have returned a
+  // 502 or 504 because it's upstream connection was down or it had no route
+  // to the server).
+  void OnNetworkChange();
+
   // Used by tests.
   int GetNumberOfEntriesForTests() const { return url_entries_.size(); }
 
  private:
   friend struct DefaultSingletonTraits<URLRequestThrottlerManager>;
 
   // From each URL we generate an ID composed of the scheme, host, port and path
   // that allows us to uniquely map an entry to it.
   typedef std::map<std::string, scoped_refptr<URLRequestThrottlerEntry> >
       UrlEntryMap;
@@ skipping 26 matching lines @@
   bool enforce_throttling_;
 
   // Certain tests do not obey the net component's threading policy, so we
   // keep track of whether we're being used by tests, and turn off certain
   // checks.
   //
   // TODO(joi): See if we can fix the offending unit tests and remove this
   // workaround.
   bool enable_thread_checks_;
 
+  // Initially false, switches to true once we have logged because of back-off
+  // being disabled for localhost.
+  bool logged_for_localhost_disabled_;
+
+  // NetLog to use, or NULL if none configured.
+  scoped_ptr<BoundNetLog> net_log_;
+
   DISALLOW_COPY_AND_ASSIGN(URLRequestThrottlerManager);
 };
 
 }  // namespace net
 
 #endif  // NET_URL_REQUEST_URL_REQUEST_THROTTLER_MANAGER_H_