1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef NET_DNS_DNS_TRANSACTION_H_
6#define NET_DNS_DNS_TRANSACTION_H_
7
8#include <string>
9
10#include "base/basictypes.h"
11#include "base/callback_forward.h"
12#include "base/memory/scoped_ptr.h"
13#include "net/base/net_export.h"
14
15namespace net {
16
17class BoundNetLog;
18class DnsResponse;
19class DnsSession;
20
21// DnsTransaction implements a stub DNS resolver as defined in RFC 1034.
22// The DnsTransaction takes care of retransmissions, name server fallback (or
23// round-robin), suffix search, and simple response validation ("does it match
24// the query") to fight poisoning.
25//
26// Destroying DnsTransaction cancels the underlying network effort.
27class NET_EXPORT_PRIVATE DnsTransaction {
28 public:
29  virtual ~DnsTransaction() {}
30
31  // Returns the original |hostname|.
32  virtual const std::string& GetHostname() const = 0;
33
34  // Returns the |qtype|.
35  virtual uint16 GetType() const = 0;
36
37  // Starts the transaction.  Always completes asynchronously.
38  virtual void Start() = 0;
39};
40
41// Creates DnsTransaction which performs asynchronous DNS search.
42// It does NOT perform caching, aggregation or prioritization of transactions.
43//
44// Destroying the factory does NOT affect any already created DnsTransactions.
45class NET_EXPORT_PRIVATE DnsTransactionFactory {
46 public:
47  // Called with the response or NULL if no matching response was received.
48  // Note that the |GetDottedName()| of the response may be different than the
49  // original |hostname| as a result of suffix search.
50  typedef base::Callback<void(DnsTransaction* transaction,
51                              int neterror,
52                              const DnsResponse* response)> CallbackType;
53
54  virtual ~DnsTransactionFactory() {}
55
56  // Creates DnsTransaction for the given |hostname| and |qtype| (assuming
57  // QCLASS is IN). |hostname| should be in the dotted form. A dot at the end
58  // implies the domain name is fully-qualified and will be exempt from suffix
59  // search. |hostname| should not be an IP literal.
60  //
61  // The transaction will run |callback| upon asynchronous completion.
62  // The |net_log| is used as the parent log.
63  virtual scoped_ptr<DnsTransaction> CreateTransaction(
64      const std::string& hostname,
65      uint16 qtype,
66      const CallbackType& callback,
67      const BoundNetLog& net_log) WARN_UNUSED_RESULT = 0;
68
69  // Creates a DnsTransactionFactory which creates DnsTransactionImpl using the
70  // |session|.
71  static scoped_ptr<DnsTransactionFactory> CreateFactory(
72      DnsSession* session) WARN_UNUSED_RESULT;
73};
74
75}  // namespace net
76
77#endif  // NET_DNS_DNS_TRANSACTION_H_
78
79