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// Copyright (c) 2011 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_QUERY_H_
#define NET_DNS_DNS_QUERY_H_
#pragma once
#include <string>
#include "base/memory/ref_counted.h"
#include "net/base/net_export.h"
#include "net/base/rand_callback.h"
namespace net {
class IOBufferWithSize;
// Represents on-the-wire DNS query message as an object.
class NET_EXPORT_PRIVATE DnsQuery {
public:
// Constructs a query message from |qname| which *MUST* be in a valid
// DNS name format, and |qtype| which must be either kDNS_A or kDNS_AAAA.
// Every generated object has a random ID, hence two objects generated
// with the same set of constructor arguments are generally not equal;
// there is a 1/2^16 chance of them being equal due to size of |id_|.
DnsQuery(const std::string& qname,
uint16 qtype,
const RandIntCallback& rand_int_cb);
~DnsQuery();
// Clones |this| verbatim, with ID field of the header regenerated.
DnsQuery* CloneWithNewId() const;
// DnsQuery field accessors.
uint16 id() const;
uint16 qtype() const;
// Returns the size of the Question section of the query. Used when
// matching the response.
size_t question_size() const;
// Returns pointer to the Question section of the query. Used when
// matching the response.
const char* question_data() const;
// IOBuffer accessor to be used for writing out the query.
IOBufferWithSize* io_buffer() const { return io_buffer_; }
private:
const std::string qname() const;
// Randomizes ID field of the query message.
void RandomizeId();
// Size of the DNS name (*NOT* hostname) we are trying to resolve; used
// to calculate offsets.
size_t qname_size_;
// Contains query bytes to be consumed by higher level Write() call.
scoped_refptr<IOBufferWithSize> io_buffer_;
// PRNG function for generating IDs.
RandIntCallback rand_int_cb_;
DISALLOW_COPY_AND_ASSIGN(DnsQuery);
};
} // namespace net
#endif // NET_DNS_DNS_QUERY_H_
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