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_SOCKET_POOL_H_
6#define NET_DNS_DNS_SOCKET_POOL_H_
7
8#include <vector>
9
10#include "base/memory/scoped_ptr.h"
11#include "net/base/net_export.h"
12#include "net/base/net_log.h"
13
14namespace net {
15
16class ClientSocketFactory;
17class DatagramClientSocket;
18class IPEndPoint;
19class NetLog;
20class StreamSocket;
21
22// A DnsSocketPool is an abstraction layer around a ClientSocketFactory that
23// allows preallocation, reuse, or other strategies to manage sockets connected
24// to DNS servers.
25class NET_EXPORT_PRIVATE DnsSocketPool {
26 public:
27  virtual ~DnsSocketPool() { }
28
29  // Creates a DnsSocketPool that implements the default strategy for managing
30  // sockets.  (This varies by platform; see DnsSocketPoolImpl in
31  // dns_socket_pool.cc for details.)
32  static scoped_ptr<DnsSocketPool> CreateDefault(
33      ClientSocketFactory* factory);
34
35  // Creates a DnsSocketPool that implements a "null" strategy -- no sockets are
36  // preallocated, allocation requests are satisfied by calling the factory
37  // directly, and returned sockets are deleted immediately.
38  static scoped_ptr<DnsSocketPool> CreateNull(
39      ClientSocketFactory* factory);
40
41  // Initializes the DnsSocketPool.  |nameservers| is the list of nameservers
42  // for which the DnsSocketPool will manage sockets; |net_log| is the NetLog
43  // used when constructing sockets with the factory.
44  //
45  // Initialize may not be called more than once, and must be called before
46  // calling AllocateSocket or FreeSocket.
47  virtual void Initialize(
48      const std::vector<IPEndPoint>* nameservers,
49      NetLog* net_log) = 0;
50
51  // Allocates a socket that is already connected to the nameserver referenced
52  // by |server_index|.  May return a scoped_ptr to NULL if no sockets are
53  // available to reuse and the factory fails to produce a socket (or produces
54  // one on which Connect fails).
55  virtual scoped_ptr<DatagramClientSocket> AllocateSocket(
56      unsigned server_index) = 0;
57
58  // Frees a socket allocated by AllocateSocket.  |server_index| must be the
59  // same index passed to AllocateSocket.
60  virtual void FreeSocket(
61      unsigned server_index,
62      scoped_ptr<DatagramClientSocket> socket) = 0;
63
64  // Creates a StreamSocket from the factory for a transaction over TCP. These
65  // sockets are not pooled.
66  scoped_ptr<StreamSocket> CreateTCPSocket(
67      unsigned server_index,
68      const NetLog::Source& source);
69
70 protected:
71  DnsSocketPool(ClientSocketFactory* socket_factory);
72
73  void InitializeInternal(
74      const std::vector<IPEndPoint>* nameservers,
75      NetLog* net_log);
76
77  scoped_ptr<DatagramClientSocket> CreateConnectedSocket(
78      unsigned server_index);
79
80 private:
81  ClientSocketFactory* socket_factory_;
82  NetLog* net_log_;
83  const std::vector<IPEndPoint>* nameservers_;
84  bool initialized_;
85
86  DISALLOW_COPY_AND_ASSIGN(DnsSocketPool);
87};
88
89} // namespace net
90
91#endif // NET_DNS_DNS_SOCKET_POOL_H_
92