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 #include "net/socket/stream_socket.h"
  17 #include "net/udp/datagram_client_socket.h"
  18
  19 namespace net {
  20
  21 DnsSession::SocketLease::SocketLease(scoped_refptr<DnsSession> session,
  22                                      unsigned server_index,
  23                                      scoped_ptr<DatagramClientSocket> socket)
  24     : session_(session), server_index_(server_index), socket_(socket.Pass()) {}
  25
  26 DnsSession::SocketLease::~SocketLease() {
  27   session_->FreeSocket(server_index_, socket_.Pass());
  28 }
  29
  30 DnsSession::DnsSession(const DnsConfig& config,
  31                        scoped_ptr<DnsSocketPool> socket_pool,
  32                        const RandIntCallback& rand_int_callback,
  33                        NetLog* net_log)
  34     : config_(config),
  35       socket_pool_(socket_pool.Pass()),
  36       rand_callback_(base::Bind(rand_int_callback, 0, kuint16max)),
  37       net_log_(net_log),
  38       server_index_(0) {
  39   socket_pool_->Initialize(&config_.nameservers, net_log);
  40 }
  41
  42 DnsSession::~DnsSession() {
  43 }
  44
  45 int DnsSession::NextQueryId() const {
  46   return rand_callback_.Run();
  47 }
  48
  49 int DnsSession::NextFirstServerIndex() {
  50   int index = server_index_;
  51   if (config_.rotate)
  52     server_index_ = (server_index_ + 1) % config_.nameservers.size();
  53   return index;
  54 }
  55
  56 base::TimeDelta DnsSession::NextTimeout(int attempt) {
  57   // The timeout doubles every full round (each nameserver once).
  58   // TODO(szym): Adapt timeout to observed RTT. http://crbug.com/110197
  59   return config_.timeout * (1 << (attempt / config_.nameservers.size()));
  60 }
  61
  62 // Allocate a socket, already connected to the server address.
  63 scoped_ptr<DnsSession::SocketLease> DnsSession::AllocateSocket(
  64     unsigned server_index,
  65     const NetLog::Source& source) {
  66   scoped_ptr<DatagramClientSocket> socket;
  67
  68   socket = socket_pool_->AllocateSocket(server_index);
  69   if (!socket.get())
  70     return scoped_ptr<SocketLease>(NULL);
  71
  72   socket->NetLog().BeginEvent(
  73       NetLog::TYPE_SOCKET_IN_USE,
  74       source.ToEventParametersCallback());
  75
  76   SocketLease* lease = new SocketLease(this, server_index, socket.Pass());
  77   return scoped_ptr<SocketLease>(lease);
  78 }
  79
  80 scoped_ptr<StreamSocket> DnsSession::CreateTCPSocket(
  81     unsigned server_index,
  82     const NetLog::Source& source) {
  83   return socket_pool_->CreateTCPSocket(server_index, source);
  84 }
  85
  86 // Release a socket.
  87 void DnsSession::FreeSocket(
  88     unsigned server_index,
  89     scoped_ptr<DatagramClientSocket> socket) {
  90   DCHECK(socket.get());
  91
  92   socket->NetLog().EndEvent(NetLog::TYPE_SOCKET_IN_USE);
  93
  94   socket_pool_->FreeSocket(server_index, socket.Pass());
  95 }
  96
  97 }  // namespace net