chrome/browser/net/dns_probe_runner.h

   1 // Copyright 2013 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_RUNNER_H_
   6 #define CHROME_BROWSER_NET_DNS_PROBE_RUNNER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/bind.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/memory/weak_ptr.h"
  12
  13 namespace net {
  14 class DnsClient;
  15 class DnsResponse;
  16 class DnsTransaction;
  17 }
  18
  19 namespace chrome_browser_net {
  20
  21 // Runs DNS probes using a single DnsClient and evaluates the responses.
  22 // (Currently requests A records for google.com and expects at least one IP
  23 // address in the response.)
  24 // Used by DnsProbeService to probe the system and public DNS configurations.
  25 class DnsProbeRunner {
  26  public:
  27   static const char* kKnownGoodHostname;
  28
  29   // Used in histograms; add new entries at the bottom, and don't remove any.
  30   enum Result {
  31     UNKNOWN,
  32     CORRECT,     // Response contains at least one A record.
  33     INCORRECT,   // Response claimed success but included no A records.
  34     FAILING,     // Response included an error or was malformed.
  35     UNREACHABLE  // No response received (timeout, network unreachable, etc.).
  36   };
  37
  38   DnsProbeRunner();
  39   ~DnsProbeRunner();
  40
  41   // Sets the DnsClient that will be used for DNS probes sent by this runner.
  42   // Must be called before RunProbe; can be called repeatedly, including during
  43   // a probe.  It will not affect an in-flight probe, if one is running.
  44   void SetClient(scoped_ptr<net::DnsClient> client);
  45
  46   // Starts a probe using the client specified with SetClient, which must have
  47   // been called before RunProbe.  |callback| will be called asynchronously
  48   // when the result is ready, even if it is ready synchronously.  Must not
  49   // be called again until the callback is called, but may be called during the
  50   // callback.
  51   void RunProbe(const base::Closure& callback);
  52
  53   // Returns true if a probe is running.  Guaranteed to return true after
  54   // RunProbe returns, and false during and after the callback.
  55   bool IsRunning() const;
  56
  57   // Returns the result of the last probe.
  58   Result result() const { return result_; }
  59
  60  private:
  61   void OnTransactionComplete(net::DnsTransaction* transaction,
  62                              int net_error,
  63                              const net::DnsResponse* response);
  64   void CallCallback();
  65
  66   base::WeakPtrFactory<DnsProbeRunner> weak_factory_;
  67
  68   scoped_ptr<net::DnsClient> client_;
  69
  70   // The callback passed to |RunProbe|.  Cleared right before calling the
  71   // callback.
  72   base::Closure callback_;
  73
  74   // The transaction started in |RunProbe| for the DNS probe.  Reset once the
  75   // results have been examined.
  76   scoped_ptr<net::DnsTransaction> transaction_;
  77
  78   Result result_;
  79
  80   DISALLOW_COPY_AND_ASSIGN(DnsProbeRunner);
  81 };
  82
  83 }  // namespace chrome_browser_net
  84
  85 #endif  // CHROME_BROWSER_NET_DNS_PROBE_RUNNER_H_