Refine IPv6 probe to require that the client has an IPv6 address on an interf...

net/base/host_resolver_impl.h

 // Copyright (c) 2006-2008 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_BASE_HOST_RESOLVER_IMPL_H_
 #define NET_BASE_HOST_RESOLVER_IMPL_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 70 matching lines @@
   // HostResolver methods:
   virtual int Resolve(const RequestInfo& info,
                       AddressList* addresses,
                       CompletionCallback* callback,
                       RequestHandle* out_req,
                       LoadLog* load_log);
   virtual void CancelRequest(RequestHandle req);
   virtual void AddObserver(HostResolver::Observer* observer);
   virtual void RemoveObserver(HostResolver::Observer* observer);
 
-  virtual void SetDefaultAddressFamily(AddressFamily address_family) {
-    default_address_family_ = address_family;
-  }
+  // Set address family, and disable IPv6 probe support.
+  virtual void SetDefaultAddressFamily(AddressFamily address_family);
+
+  // Continuously observe whether IPv6 is supported, and set the allowable
+  // address family to IPv4 iff IPv6 is not supported.
+  void ProbeIPv6Support();
 
   virtual HostResolverImpl* GetAsHostResolverImpl() { return this; }
 
   // TODO(eroman): hack for http://crbug.com/15513
   void Shutdown();
 
   // Returns the cache this resolver uses, or NULL if caching is disabled.
   HostCache* cache() { return cache_.get(); }
 
   // Clears the request trace log.
@@ skipping 133 matching lines @@
   scoped_refptr<HostResolverProc> resolver_proc_;
 
   // Address family to use when the request doesn't specify one.
   AddressFamily default_address_family_;
 
   // TODO(eroman): hack for http://crbug.com/15513
   bool shutdown_;
 
   NetworkChangeNotifier* const network_change_notifier_;
 
+  // Indicate if probing is done after each network change event to set address
+  // family.
+  // When false, explicit setting of address family is used.
+  bool ipv6_probe_monitoring_;
+
   scoped_refptr<RequestsTrace> requests_trace_;
 
   DISALLOW_COPY_AND_ASSIGN(HostResolverImpl);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_HOST_RESOLVER_IMPL_H_