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 30 namespace asio { 31 namespace detail { 32 33 template <typename Protocol, typename Handler> 34 class resolve_op : public operation 35 { 36 public: 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 resolve_op(socket_ops::weak_cancel_token_type cancel_token,const query_type & query,io_service_impl & ios,Handler & handler)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 ~resolve_op()53 ~resolve_op() 54 { 55 if (addrinfo_) 56 socket_ops::freeaddrinfo(addrinfo_); 57 } 58 do_complete(io_service_impl * owner,operation * base,const asio::error_code &,std::size_t)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 } 113 114 private: 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