boost/asio/detail/resolve_op.hpp

   1 //
   2 // detail/resolve_op.hpp
   3 // ~~~~~~~~~~~~~~~~~~~~~
   4 //
   5 // Copyright (c) 2003-2017 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 BOOST_ASIO_DETAIL_RESOLVE_OP_HPP
  12 #define BOOST_ASIO_DETAIL_RESOLVE_OP_HPP
  13
  14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  15 # pragma once
  16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  17
  18 #include <boost/asio/detail/config.hpp>
  19 #include <boost/asio/error.hpp>
  20 #include <boost/asio/io_service.hpp>
  21 #include <boost/asio/ip/basic_resolver_iterator.hpp>
  22 #include <boost/asio/ip/basic_resolver_query.hpp>
  23 #include <boost/asio/detail/addressof.hpp>
  24 #include <boost/asio/detail/bind_handler.hpp>
  25 #include <boost/asio/detail/fenced_block.hpp>
  26 #include <boost/asio/detail/handler_alloc_helpers.hpp>
  27 #include <boost/asio/detail/handler_invoke_helpers.hpp>
  28 #include <boost/asio/detail/operation.hpp>
  29 #include <boost/asio/detail/socket_ops.hpp>
  30
  31 #include <boost/asio/detail/push_options.hpp>
  32
  33 namespace boost {
  34 namespace asio {
  35 namespace detail {
  36
  37 template <typename Protocol, typename Handler>
  38 class resolve_op : public operation
  39 {
  40 public:
  41   BOOST_ASIO_DEFINE_HANDLER_PTR(resolve_op);
  42
  43   typedef boost::asio::ip::basic_resolver_query<Protocol> query_type;
  44   typedef boost::asio::ip::basic_resolver_iterator<Protocol> iterator_type;
  45
  46   resolve_op(socket_ops::weak_cancel_token_type cancel_token,
  47       const query_type& query, io_service_impl& ios, Handler& handler)
  48     : operation(&resolve_op::do_complete),
  49       cancel_token_(cancel_token),
  50       query_(query),
  51       io_service_impl_(ios),
  52       handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler)),
  53       addrinfo_(0)
  54   {
  55   }
  56
  57   ~resolve_op()
  58   {
  59     if (addrinfo_)
  60       socket_ops::freeaddrinfo(addrinfo_);
  61   }
  62
  63   static void do_complete(io_service_impl* owner, operation* base,
  64       const boost::system::error_code& /*ec*/,
  65       std::size_t /*bytes_transferred*/)
  66   {
  67     // Take ownership of the operation object.
  68     resolve_op* o(static_cast<resolve_op*>(base));
  69     ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
  70
  71     if (owner && owner != &o->io_service_impl_)
  72     {
  73       // The operation is being run on the worker io_service. Time to perform
  74       // the resolver operation.
  75
  76       // Perform the blocking host resolution operation.
  77       socket_ops::background_getaddrinfo(o->cancel_token_,
  78           o->query_.host_name().c_str(), o->query_.service_name().c_str(),
  79           o->query_.hints(), &o->addrinfo_, o->ec_);
  80
  81       // Pass operation back to main io_service for completion.
  82       o->io_service_impl_.post_deferred_completion(o);
  83       p.v = p.p = 0;
  84     }
  85     else
  86     {
  87       // The operation has been returned to the main io_service. The completion
  88       // handler is ready to be delivered.
  89
  90       BOOST_ASIO_HANDLER_COMPLETION((o));
  91
  92       // Make a copy of the handler so that the memory can be deallocated
  93       // before the upcall is made. Even if we're not about to make an upcall,
  94       // a sub-object of the handler may be the true owner of the memory
  95       // associated with the handler. Consequently, a local copy of the handler
  96       // is required to ensure that any owning sub-object remains valid until
  97       // after we have deallocated the memory here.
  98       detail::binder2<Handler, boost::system::error_code, iterator_type>
  99         handler(o->handler_, o->ec_, iterator_type());
 100       p.h = boost::asio::detail::addressof(handler.handler_);
 101       if (o->addrinfo_)
 102       {
 103         handler.arg2_ = iterator_type::create(o->addrinfo_,
 104             o->query_.host_name(), o->query_.service_name());
 105       }
 106       p.reset();
 107
 108       if (owner)
 109       {
 110         fenced_block b(fenced_block::half);
 111         BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, "..."));
 112         boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
 113         BOOST_ASIO_HANDLER_INVOCATION_END;
 114       }
 115     }
 116   }
 117
 118 private:
 119   socket_ops::weak_cancel_token_type cancel_token_;
 120   query_type query_;
 121   io_service_impl& io_service_impl_;
 122   Handler handler_;
 123   boost::system::error_code ec_;
 124   boost::asio::detail::addrinfo_type* addrinfo_;
 125 };
 126
 127 } // namespace detail
 128 } // namespace asio
 129 } // namespace boost
 130
 131 #include <boost/asio/detail/pop_options.hpp>
 132
 133 #endif // BOOST_ASIO_DETAIL_RESOLVE_OP_HPP