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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.
#include <string>
#include "base/basictypes.h"
#include "base/callback_forward.h"
#include "base/memory/scoped_ptr.h"
#include "net/base/net_export.h"
namespace net {
class BoundNetLog;
class DnsResponse;
class DnsSession;
// DnsTransaction implements a stub DNS resolver as defined in RFC 1034.
// The DnsTransaction takes care of retransmissions, name server fallback (or
// round-robin), suffix search, and simple response validation ("does it match
// the query") to fight poisoning.
// Destroying DnsTransaction cancels the underlying network effort.
class NET_EXPORT_PRIVATE DnsTransaction {
virtual ~DnsTransaction() {}
// Returns the original |hostname|.
virtual const std::string& GetHostname() const = 0;
// Returns the |qtype|.
virtual uint16 GetType() const = 0;
// Starts the transaction. Always completes asynchronously.
virtual void Start() = 0;
// Creates DnsTransaction which performs asynchronous DNS search.
// It does NOT perform caching, aggregation or prioritization of transactions.
// Destroying the factory does NOT affect any already created DnsTransactions.
class NET_EXPORT_PRIVATE DnsTransactionFactory {
// Called with the response or NULL if no matching response was received.
// Note that the |GetDottedName()| of the response may be different than the
// original |hostname| as a result of suffix search.
typedef base::Callback<void(DnsTransaction* transaction,
int neterror,
const DnsResponse* response)> CallbackType;
virtual ~DnsTransactionFactory() {}
// Creates DnsTransaction for the given |hostname| and |qtype| (assuming
// QCLASS is IN). |hostname| should be in the dotted form. A dot at the end
// implies the domain name is fully-qualified and will be exempt from suffix
// search. |hostname| should not be an IP literal.
// The transaction will run |callback| upon asynchronous completion.
// The |net_log| is used as the parent log.
virtual scoped_ptr<DnsTransaction> CreateTransaction(
const std::string& hostname,
uint16 qtype,
const CallbackType& callback,
const BoundNetLog& net_log) WARN_UNUSED_RESULT = 0;
// Creates a DnsTransactionFactory which creates DnsTransactionImpl using the
// |session|.
static scoped_ptr<DnsTransactionFactory> CreateFactory(
DnsSession* session) WARN_UNUSED_RESULT;
} // namespace net