chrome/browser/net/dns_probe_service.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_NET_DNS_PROBE_SERVICE_H_
   6 #define CHROME_BROWSER_NET_DNS_PROBE_SERVICE_H_
   7
   8 #include <vector>
   9
  10 #include "base/basictypes.h"
  11 #include "base/bind.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/time/time.h"
  14 #include "chrome/browser/net/dns_probe_runner.h"
  15 #include "components/error_page/common/net_error_info.h"
  16 #include "net/base/network_change_notifier.h"
  17
  18 namespace net {
  19 class DnsClient;
  20 struct DnsConfig;
  21 }
  22
  23 namespace chrome_browser_net {
  24
  25 // Probes the system and public DNS servers to determine the (probable) cause
  26 // of a recent DNS-related page load error.  Coalesces multiple probe requests
  27 // (perhaps from multiple tabs) and caches the results.
  28 //
  29 // Uses a single DNS attempt per config, and doesn't randomize source ports.
  30 class DnsProbeService : public net::NetworkChangeNotifier::DNSObserver {
  31  public:
  32   typedef base::Callback<void(error_page::DnsProbeStatus result)>
  33       ProbeCallback;
  34
  35   DnsProbeService();
  36   ~DnsProbeService() override;
  37
  38   virtual void ProbeDns(const ProbeCallback& callback);
  39
  40   // NetworkChangeNotifier::DNSObserver implementation:
  41   void OnDNSChanged() override;
  42   void OnInitialDNSConfigRead() override;
  43
  44   void SetSystemClientForTesting(scoped_ptr<net::DnsClient> system_client);
  45   void SetPublicClientForTesting(scoped_ptr<net::DnsClient> public_client);
  46   void ClearCachedResultForTesting();
  47
  48  private:
  49   enum State {
  50     STATE_NO_RESULT,
  51     STATE_PROBE_RUNNING,
  52     STATE_RESULT_CACHED,
  53   };
  54
  55   void SetSystemClientToCurrentConfig();
  56   void SetPublicClientToGooglePublicDns();
  57
  58   // Starts a probe (runs system and public probes).
  59   void StartProbes();
  60   void OnProbeComplete();
  61   // Calls all |pending_callbacks_| with the |cached_result_|.
  62   void CallCallbacks();
  63   // Clears a cached probe result.
  64   void ClearCachedResult();
  65
  66   bool CachedResultIsExpired() const;
  67
  68   State state_;
  69   std::vector<ProbeCallback> pending_callbacks_;
  70   base::Time probe_start_time_;
  71   error_page::DnsProbeStatus cached_result_;
  72
  73   // DnsProbeRunners for the system DNS configuration and a public DNS server.
  74   DnsProbeRunner system_runner_;
  75   DnsProbeRunner public_runner_;
  76
  77   DISALLOW_COPY_AND_ASSIGN(DnsProbeService);
  78 };
  79
  80 }  // namespace chrome_browser_net
  81
  82 #endif  // CHROME_BROWSER_NET_DNS_PROBE_SERVICE_H_