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      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_
     86