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// 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.
#ifndef NET_DNS_DNS_SESSION_H_
#define NET_DNS_DNS_SESSION_H_
#include "base/memory/ref_counted.h"
#include "base/time.h"
#include "net/base/net_export.h"
#include "net/base/rand_callback.h"
#include "net/dns/dns_config_service.h"
namespace net {
class ClientSocketFactory;
class NetLog;
// Session parameters and state shared between DNS transactions.
// Ref-counted so that DnsClient::Request can keep working in absence of
// DnsClient. A DnsSession must be recreated when DnsConfig changes.
class NET_EXPORT_PRIVATE DnsSession
: NON_EXPORTED_BASE(public base::RefCounted<DnsSession>) {
public:
typedef base::Callback<int()> RandCallback;
DnsSession(const DnsConfig& config,
ClientSocketFactory* factory,
const RandIntCallback& rand_int_callback,
NetLog* net_log);
const DnsConfig& config() const { return config_; }
NetLog* net_log() const { return net_log_; }
ClientSocketFactory* socket_factory() { return socket_factory_; }
// Return the next random query ID.
int NextQueryId() const;
// Return the index of the first configured server to use on first attempt.
int NextFirstServerIndex();
// Return the timeout for the next query.
base::TimeDelta NextTimeout(int attempt);
private:
friend class base::RefCounted<DnsSession>;
~DnsSession();
const DnsConfig config_;
ClientSocketFactory* socket_factory_;
RandCallback rand_callback_;
NetLog* net_log_;
// Current index into |config_.nameservers| to begin resolution with.
int server_index_;
// TODO(szym): Add current RTT estimate.
// TODO(szym): Add TCP connection pool to support DNS over TCP.
// TODO(szym): Add UDP port pool to avoid NAT table overload.
DISALLOW_COPY_AND_ASSIGN(DnsSession);
};
} // namespace net
#endif // NET_DNS_DNS_SESSION_H_
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