net/dns/dns_session.cc

   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 #include "net/dns/dns_session.h"
   6
   7 #include "base/basictypes.h"
   8 #include "base/bind.h"
   9 #include "base/rand_util.h"
  10 #include "base/stl_util.h"
  11 #include "base/time.h"
  12 #include "net/base/ip_endpoint.h"
  13 #include "net/base/net_errors.h"
  14 #include "net/dns/dns_config_service.h"
  15 #include "net/dns/dns_socket_pool.h"
  16
  17 namespace net {
  18
  19 DnsSession::SocketLease::SocketLease(scoped_refptr<DnsSession> session,
  20                                      unsigned server_index,
  21                                      scoped_ptr<DatagramClientSocket> socket)
  22     : session_(session), server_index_(server_index), socket_(socket.Pass()) {}
  23
  24 DnsSession::SocketLease::~SocketLease() {
  25   session_->FreeSocket(server_index_, socket_.Pass());
  26 }
  27
  28 DnsSession::DnsSession(const DnsConfig& config,
  29                        scoped_ptr<DnsSocketPool> socket_pool,
  30                        const RandIntCallback& rand_int_callback,
  31                        NetLog* net_log)
  32     : config_(config),
  33       socket_pool_(socket_pool.Pass()),
  34       rand_callback_(base::Bind(rand_int_callback, 0, kuint16max)),
  35       net_log_(net_log),
  36       server_index_(0) {
  37   socket_pool_->Initialize(&config_.nameservers, net_log);
  38 }
  39
  40 DnsSession::~DnsSession() {
  41 }
  42
  43 int DnsSession::NextQueryId() const {
  44   return rand_callback_.Run();
  45 }
  46
  47 int DnsSession::NextFirstServerIndex() {
  48   int index = server_index_;
  49   if (config_.rotate)
  50     server_index_ = (server_index_ + 1) % config_.nameservers.size();
  51   return index;
  52 }
  53
  54 base::TimeDelta DnsSession::NextTimeout(int attempt) {
  55   // The timeout doubles every full round (each nameserver once).
  56   // TODO(szym): Adapt timeout to observed RTT. http://crbug.com/110197
  57   return config_.timeout * (1 << (attempt / config_.nameservers.size()));
  58 }
  59
  60 // Allocate a socket, already connected to the server address.
  61 scoped_ptr<DnsSession::SocketLease> DnsSession::AllocateSocket(
  62     unsigned server_index,
  63     const NetLog::Source& source) {
  64   scoped_ptr<DatagramClientSocket> socket;
  65
  66   socket = socket_pool_->AllocateSocket(server_index);
  67   if (!socket.get())
  68     return scoped_ptr<SocketLease>(NULL);
  69
  70   socket->NetLog().BeginEvent(
  71       NetLog::TYPE_SOCKET_IN_USE,
  72       source.ToEventParametersCallback());
  73
  74   SocketLease* lease = new SocketLease(this, server_index, socket.Pass());
  75   return scoped_ptr<SocketLease>(lease);
  76 }
  77
  78 // Release a socket.
  79 void DnsSession::FreeSocket(
  80     unsigned server_index,
  81     scoped_ptr<DatagramClientSocket> socket) {
  82   DCHECK(socket.get());
  83
  84   socket->NetLog().EndEvent(NetLog::TYPE_SOCKET_IN_USE);
  85
  86   socket_pool_->FreeSocket(server_index, socket.Pass());
  87 }
  88
  89 }  // namespace net