[net/dns] Resolve AF_UNSPEC on dual-stacked systems. Sort addresses according to RFC3484.

net/dns/dns_client.cc

 // Copyright (c) 2012 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.
 
 #include "net/dns/dns_client.h"
 
 #include "base/bind.h"
 #include "base/rand_util.h"
 #include "net/base/net_log.h"
+#include "net/dns/address_sorter.h"
 #include "net/dns/dns_config_service.h"
 #include "net/dns/dns_session.h"
 #include "net/dns/dns_transaction.h"
 #include "net/socket/client_socket_factory.h"
 
 namespace net {
 
 namespace {
 
 class DnsClientImpl : public DnsClient {
  public:
-  explicit DnsClientImpl(NetLog* net_log) : net_log_(net_log) {}
+  explicit DnsClientImpl(NetLog* net_log)
+      : address_sorter_(AddressSorter::CreateAddressSorter()),
+        net_log_(net_log) {}
 
   virtual void SetConfig(const DnsConfig& config) OVERRIDE {
     factory_.reset();
     session_.release();
     if (config.IsValid()) {
       session_ = new DnsSession(config,
                                 ClientSocketFactory::GetDefaultFactory(),
                                 base::Bind(&base::RandInt),
                                 net_log_);
       factory_ = DnsTransactionFactory::CreateFactory(session_);
     }
   }
 
   virtual const DnsConfig* GetConfig() const OVERRIDE {
     return session_.get() ? &session_->config() : NULL;
   }
 
   virtual DnsTransactionFactory* GetTransactionFactory() OVERRIDE {
     return session_.get() ? factory_.get() : NULL;
   }
 
+  virtual AddressSorter* GetAddressSorter() OVERRIDE {
+    return address_sorter_.get();
+  }
+
  private:
   scoped_refptr<DnsSession> session_;
   scoped_ptr<DnsTransactionFactory> factory_;
+  scoped_ptr<AddressSorter> address_sorter_;
 
   NetLog* net_log_;
 };
 
 }  // namespace
 
 // static
 scoped_ptr<DnsClient> DnsClient::CreateClient(NetLog* net_log) {
   return scoped_ptr<DnsClient>(new DnsClientImpl(net_log));
 }
 
 }  // namespace net