1//
2// detail/resolve_op.hpp
3// ~~~~~~~~~~~~~~~~~~~~~
4//
5// Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6//
7// Distributed under the Boost Software License, Version 1.0. (See accompanying
8// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9//
10
11#ifndef ASIO_DETAIL_RESOLVE_OP_HPP
12#define ASIO_DETAIL_RESOLVE_OP_HPP
13
14
15#include "asio/detail/config.hpp"
16#include "asio/error.hpp"
17#include "asio/io_service.hpp"
18#include "asio/ip/basic_resolver_iterator.hpp"
19#include "asio/ip/basic_resolver_query.hpp"
20#include "asio/detail/addressof.hpp"
21#include "asio/detail/bind_handler.hpp"
22#include "asio/detail/fenced_block.hpp"
23#include "asio/detail/handler_alloc_helpers.hpp"
24#include "asio/detail/handler_invoke_helpers.hpp"
25#include "asio/detail/operation.hpp"
26#include "asio/detail/socket_ops.hpp"
27
28#include "asio/detail/push_options.hpp"
29
30namespace asio {
31namespace detail {
32
33template <typename Protocol, typename Handler>
34class resolve_op : public operation
35{
36public:
37  ASIO_DEFINE_HANDLER_PTR(resolve_op);
38
39  typedef asio::ip::basic_resolver_query<Protocol> query_type;
40  typedef asio::ip::basic_resolver_iterator<Protocol> iterator_type;
41
42  resolve_op(socket_ops::weak_cancel_token_type cancel_token,
43      const query_type& query, io_service_impl& ios, Handler& handler)
44    : operation(&resolve_op::do_complete),
45      cancel_token_(cancel_token),
46      query_(query),
47      io_service_impl_(ios),
48      handler_(ASIO_MOVE_CAST(Handler)(handler)),
49      addrinfo_(0)
50  {
51  }
52
53  ~resolve_op()
54  {
55    if (addrinfo_)
56      socket_ops::freeaddrinfo(addrinfo_);
57  }
58
59  static void do_complete(io_service_impl* owner, operation* base,
60      const asio::error_code& /*ec*/,
61      std::size_t /*bytes_transferred*/)
62  {
63    // Take ownership of the operation object.
64    resolve_op* o(static_cast<resolve_op*>(base));
65    ptr p = { asio::detail::addressof(o->handler_), o, o };
66
67    if (owner && owner != &o->io_service_impl_)
68    {
69      // The operation is being run on the worker io_service. Time to perform
70      // the resolver operation.
71
72      // Perform the blocking host resolution operation.
73      socket_ops::background_getaddrinfo(o->cancel_token_,
74          o->query_.host_name().c_str(), o->query_.service_name().c_str(),
75          o->query_.hints(), &o->addrinfo_, o->ec_);
76
77      // Pass operation back to main io_service for completion.
78      o->io_service_impl_.post_deferred_completion(o);
79      p.v = p.p = 0;
80    }
81    else
82    {
83      // The operation has been returned to the main io_service. The completion
84      // handler is ready to be delivered.
85
86      ASIO_HANDLER_COMPLETION((o));
87
88      // Make a copy of the handler so that the memory can be deallocated
89      // before the upcall is made. Even if we're not about to make an upcall,
90      // a sub-object of the handler may be the true owner of the memory
91      // associated with the handler. Consequently, a local copy of the handler
92      // is required to ensure that any owning sub-object remains valid until
93      // after we have deallocated the memory here.
94      detail::binder2<Handler, asio::error_code, iterator_type>
95        handler(o->handler_, o->ec_, iterator_type());
96      p.h = asio::detail::addressof(handler.handler_);
97      if (o->addrinfo_)
98      {
99        handler.arg2_ = iterator_type::create(o->addrinfo_,
100            o->query_.host_name(), o->query_.service_name());
101      }
102      p.reset();
103
104      if (owner)
105      {
106        fenced_block b(fenced_block::half);
107        ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, "..."));
108        asio_handler_invoke_helpers::invoke(handler, handler.handler_);
109        ASIO_HANDLER_INVOCATION_END;
110      }
111    }
112  }
113
114private:
115  socket_ops::weak_cancel_token_type cancel_token_;
116  query_type query_;
117  io_service_impl& io_service_impl_;
118  Handler handler_;
119  asio::error_code ec_;
120  asio::detail::addrinfo_type* addrinfo_;
121};
122
123} // namespace detail
124} // namespace asio
125
126#include "asio/detail/pop_options.hpp"
127
128#endif // ASIO_DETAIL_RESOLVE_OP_HPP
129