| 
							- //
 - // basic_socket.hpp
 - // ~~~~~~~~~~~~~~~~
 - //
 - // Copyright (c) 2003-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 - //
 - // Distributed under the Boost Software License, Version 1.0. (See accompanying
 - // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 - //
 - 
 - #ifndef ASIO_BASIC_SOCKET_HPP
 - #define ASIO_BASIC_SOCKET_HPP
 - 
 - #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 - # pragma once
 - #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 - 
 - #include "asio/detail/config.hpp"
 - #include "asio/async_result.hpp"
 - #include "asio/detail/handler_type_requirements.hpp"
 - #include "asio/detail/io_object_impl.hpp"
 - #include "asio/detail/non_const_lvalue.hpp"
 - #include "asio/detail/throw_error.hpp"
 - #include "asio/detail/type_traits.hpp"
 - #include "asio/error.hpp"
 - #include "asio/execution_context.hpp"
 - #include "asio/executor.hpp"
 - #include "asio/post.hpp"
 - #include "asio/socket_base.hpp"
 - 
 - #if defined(ASIO_WINDOWS_RUNTIME)
 - # include "asio/detail/null_socket_service.hpp"
 - #elif defined(ASIO_HAS_IOCP)
 - # include "asio/detail/win_iocp_socket_service.hpp"
 - #else
 - # include "asio/detail/reactive_socket_service.hpp"
 - #endif
 - 
 - #if defined(ASIO_HAS_MOVE)
 - # include <utility>
 - #endif // defined(ASIO_HAS_MOVE)
 - 
 - #include "asio/detail/push_options.hpp"
 - 
 - namespace asio {
 - 
 - #if !defined(ASIO_BASIC_SOCKET_FWD_DECL)
 - #define ASIO_BASIC_SOCKET_FWD_DECL
 - 
 - // Forward declaration with defaulted arguments.
 - template <typename Protocol, typename Executor = executor>
 - class basic_socket;
 - 
 - #endif // !defined(ASIO_BASIC_SOCKET_FWD_DECL)
 - 
 - /// Provides socket functionality.
 - /**
 -  * The basic_socket class template provides functionality that is common to both
 -  * stream-oriented and datagram-oriented sockets.
 -  *
 -  * @par Thread Safety
 -  * @e Distinct @e objects: Safe.@n
 -  * @e Shared @e objects: Unsafe.
 -  */
 - template <typename Protocol, typename Executor>
 - class basic_socket
 -   : public socket_base
 - {
 - public:
 -   /// The type of the executor associated with the object.
 -   typedef Executor executor_type;
 - 
 -   /// Rebinds the socket type to another executor.
 -   template <typename Executor1>
 -   struct rebind_executor
 -   {
 -     /// The socket type when rebound to the specified executor.
 -     typedef basic_socket<Protocol, Executor1> other;
 -   };
 - 
 -   /// The native representation of a socket.
 - #if defined(GENERATING_DOCUMENTATION)
 -   typedef implementation_defined native_handle_type;
 - #elif defined(ASIO_WINDOWS_RUNTIME)
 -   typedef typename detail::null_socket_service<
 -     Protocol>::native_handle_type native_handle_type;
 - #elif defined(ASIO_HAS_IOCP)
 -   typedef typename detail::win_iocp_socket_service<
 -     Protocol>::native_handle_type native_handle_type;
 - #else
 -   typedef typename detail::reactive_socket_service<
 -     Protocol>::native_handle_type native_handle_type;
 - #endif
 - 
 -   /// The protocol type.
 -   typedef Protocol protocol_type;
 - 
 -   /// The endpoint type.
 -   typedef typename Protocol::endpoint endpoint_type;
 - 
 - #if !defined(ASIO_NO_EXTENSIONS)
 -   /// A basic_socket is always the lowest layer.
 -   typedef basic_socket<Protocol, Executor> lowest_layer_type;
 - #endif // !defined(ASIO_NO_EXTENSIONS)
 - 
 -   /// Construct a basic_socket without opening it.
 -   /**
 -    * This constructor creates a socket without opening it.
 -    *
 -    * @param ex The I/O executor that the socket will use, by default, to
 -    * dispatch handlers for any asynchronous operations performed on the socket.
 -    */
 -   explicit basic_socket(const executor_type& ex)
 -     : impl_(ex)
 -   {
 -   }
 - 
 -   /// Construct a basic_socket without opening it.
 -   /**
 -    * This constructor creates a socket without opening it.
 -    *
 -    * @param context An execution context which provides the I/O executor that
 -    * the socket will use, by default, to dispatch handlers for any asynchronous
 -    * operations performed on the socket.
 -    */
 -   template <typename ExecutionContext>
 -   explicit basic_socket(ExecutionContext& context,
 -       typename enable_if<
 -         is_convertible<ExecutionContext&, execution_context&>::value
 -       >::type* = 0)
 -     : impl_(context)
 -   {
 -   }
 - 
 -   /// Construct and open a basic_socket.
 -   /**
 -    * This constructor creates and opens a socket.
 -    *
 -    * @param ex The I/O executor that the socket will use, by default, to
 -    * dispatch handlers for any asynchronous operations performed on the socket.
 -    *
 -    * @param protocol An object specifying protocol parameters to be used.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    */
 -   basic_socket(const executor_type& ex, const protocol_type& protocol)
 -     : impl_(ex)
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().open(impl_.get_implementation(), protocol, ec);
 -     asio::detail::throw_error(ec, "open");
 -   }
 - 
 -   /// Construct and open a basic_socket.
 -   /**
 -    * This constructor creates and opens a socket.
 -    *
 -    * @param context An execution context which provides the I/O executor that
 -    * the socket will use, by default, to dispatch handlers for any asynchronous
 -    * operations performed on the socket.
 -    *
 -    * @param protocol An object specifying protocol parameters to be used.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    */
 -   template <typename ExecutionContext>
 -   basic_socket(ExecutionContext& context, const protocol_type& protocol,
 -       typename enable_if<
 -         is_convertible<ExecutionContext&, execution_context&>::value
 -       >::type* = 0)
 -     : impl_(context)
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().open(impl_.get_implementation(), protocol, ec);
 -     asio::detail::throw_error(ec, "open");
 -   }
 - 
 -   /// Construct a basic_socket, opening it and binding it to the given local
 -   /// endpoint.
 -   /**
 -    * This constructor creates a socket and automatically opens it bound to the
 -    * specified endpoint on the local machine. The protocol used is the protocol
 -    * associated with the given endpoint.
 -    *
 -    * @param ex The I/O executor that the socket will use, by default, to
 -    * dispatch handlers for any asynchronous operations performed on the socket.
 -    *
 -    * @param endpoint An endpoint on the local machine to which the socket will
 -    * be bound.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    */
 -   basic_socket(const executor_type& ex, const endpoint_type& endpoint)
 -     : impl_(ex)
 -   {
 -     asio::error_code ec;
 -     const protocol_type protocol = endpoint.protocol();
 -     impl_.get_service().open(impl_.get_implementation(), protocol, ec);
 -     asio::detail::throw_error(ec, "open");
 -     impl_.get_service().bind(impl_.get_implementation(), endpoint, ec);
 -     asio::detail::throw_error(ec, "bind");
 -   }
 - 
 -   /// Construct a basic_socket, opening it and binding it to the given local
 -   /// endpoint.
 -   /**
 -    * This constructor creates a socket and automatically opens it bound to the
 -    * specified endpoint on the local machine. The protocol used is the protocol
 -    * associated with the given endpoint.
 -    *
 -    * @param context An execution context which provides the I/O executor that
 -    * the socket will use, by default, to dispatch handlers for any asynchronous
 -    * operations performed on the socket.
 -    *
 -    * @param endpoint An endpoint on the local machine to which the socket will
 -    * be bound.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    */
 -   template <typename ExecutionContext>
 -   basic_socket(ExecutionContext& context, const endpoint_type& endpoint,
 -       typename enable_if<
 -         is_convertible<ExecutionContext&, execution_context&>::value
 -       >::type* = 0)
 -     : impl_(context)
 -   {
 -     asio::error_code ec;
 -     const protocol_type protocol = endpoint.protocol();
 -     impl_.get_service().open(impl_.get_implementation(), protocol, ec);
 -     asio::detail::throw_error(ec, "open");
 -     impl_.get_service().bind(impl_.get_implementation(), endpoint, ec);
 -     asio::detail::throw_error(ec, "bind");
 -   }
 - 
 -   /// Construct a basic_socket on an existing native socket.
 -   /**
 -    * This constructor creates a socket object to hold an existing native socket.
 -    *
 -    * @param ex The I/O executor that the socket will use, by default, to
 -    * dispatch handlers for any asynchronous operations performed on the socket.
 -    *
 -    * @param protocol An object specifying protocol parameters to be used.
 -    *
 -    * @param native_socket A native socket.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    */
 -   basic_socket(const executor_type& ex, const protocol_type& protocol,
 -       const native_handle_type& native_socket)
 -     : impl_(ex)
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().assign(impl_.get_implementation(),
 -         protocol, native_socket, ec);
 -     asio::detail::throw_error(ec, "assign");
 -   }
 - 
 -   /// Construct a basic_socket on an existing native socket.
 -   /**
 -    * This constructor creates a socket object to hold an existing native socket.
 -    *
 -    * @param context An execution context which provides the I/O executor that
 -    * the socket will use, by default, to dispatch handlers for any asynchronous
 -    * operations performed on the socket.
 -    *
 -    * @param protocol An object specifying protocol parameters to be used.
 -    *
 -    * @param native_socket A native socket.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    */
 -   template <typename ExecutionContext>
 -   basic_socket(ExecutionContext& context, const protocol_type& protocol,
 -       const native_handle_type& native_socket,
 -       typename enable_if<
 -         is_convertible<ExecutionContext&, execution_context&>::value
 -       >::type* = 0)
 -     : impl_(context)
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().assign(impl_.get_implementation(),
 -         protocol, native_socket, ec);
 -     asio::detail::throw_error(ec, "assign");
 -   }
 - 
 - #if defined(ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 -   /// Move-construct a basic_socket from another.
 -   /**
 -    * This constructor moves a socket from one object to another.
 -    *
 -    * @param other The other basic_socket object from which the move will
 -    * occur.
 -    *
 -    * @note Following the move, the moved-from object is in the same state as if
 -    * constructed using the @c basic_socket(const executor_type&) constructor.
 -    */
 -   basic_socket(basic_socket&& other)
 -     : impl_(std::move(other.impl_))
 -   {
 -   }
 - 
 -   /// Move-assign a basic_socket from another.
 -   /**
 -    * This assignment operator moves a socket from one object to another.
 -    *
 -    * @param other The other basic_socket object from which the move will
 -    * occur.
 -    *
 -    * @note Following the move, the moved-from object is in the same state as if
 -    * constructed using the @c basic_socket(const executor_type&) constructor.
 -    */
 -   basic_socket& operator=(basic_socket&& other)
 -   {
 -     impl_ = std::move(other.impl_);
 -     return *this;
 -   }
 - 
 -   // All sockets have access to each other's implementations.
 -   template <typename Protocol1, typename Executor1>
 -   friend class basic_socket;
 - 
 -   /// Move-construct a basic_socket from a socket of another protocol type.
 -   /**
 -    * This constructor moves a socket from one object to another.
 -    *
 -    * @param other The other basic_socket object from which the move will
 -    * occur.
 -    *
 -    * @note Following the move, the moved-from object is in the same state as if
 -    * constructed using the @c basic_socket(const executor_type&) constructor.
 -    */
 -   template <typename Protocol1, typename Executor1>
 -   basic_socket(basic_socket<Protocol1, Executor1>&& other,
 -       typename enable_if<
 -         is_convertible<Protocol1, Protocol>::value
 -           && is_convertible<Executor1, Executor>::value
 -       >::type* = 0)
 -     : impl_(std::move(other.impl_))
 -   {
 -   }
 - 
 -   /// Move-assign a basic_socket from a socket of another protocol type.
 -   /**
 -    * This assignment operator moves a socket from one object to another.
 -    *
 -    * @param other The other basic_socket object from which the move will
 -    * occur.
 -    *
 -    * @note Following the move, the moved-from object is in the same state as if
 -    * constructed using the @c basic_socket(const executor_type&) constructor.
 -    */
 -   template <typename Protocol1, typename Executor1>
 -   typename enable_if<
 -     is_convertible<Protocol1, Protocol>::value
 -       && is_convertible<Executor1, Executor>::value,
 -     basic_socket&
 -   >::type operator=(basic_socket<Protocol1, Executor1> && other)
 -   {
 -     basic_socket tmp(std::move(other));
 -     impl_ = std::move(tmp.impl_);
 -     return *this;
 -   }
 - #endif // defined(ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
 - 
 -   /// Get the executor associated with the object.
 -   executor_type get_executor() ASIO_NOEXCEPT
 -   {
 -     return impl_.get_executor();
 -   }
 - 
 - #if !defined(ASIO_NO_EXTENSIONS)
 -   /// Get a reference to the lowest layer.
 -   /**
 -    * This function returns a reference to the lowest layer in a stack of
 -    * layers. Since a basic_socket cannot contain any further layers, it simply
 -    * returns a reference to itself.
 -    *
 -    * @return A reference to the lowest layer in the stack of layers. Ownership
 -    * is not transferred to the caller.
 -    */
 -   lowest_layer_type& lowest_layer()
 -   {
 -     return *this;
 -   }
 - 
 -   /// Get a const reference to the lowest layer.
 -   /**
 -    * This function returns a const reference to the lowest layer in a stack of
 -    * layers. Since a basic_socket cannot contain any further layers, it simply
 -    * returns a reference to itself.
 -    *
 -    * @return A const reference to the lowest layer in the stack of layers.
 -    * Ownership is not transferred to the caller.
 -    */
 -   const lowest_layer_type& lowest_layer() const
 -   {
 -     return *this;
 -   }
 - #endif // !defined(ASIO_NO_EXTENSIONS)
 - 
 -   /// Open the socket using the specified protocol.
 -   /**
 -    * This function opens the socket so that it will use the specified protocol.
 -    *
 -    * @param protocol An object specifying protocol parameters to be used.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    *
 -    * @par Example
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * socket.open(asio::ip::tcp::v4());
 -    * @endcode
 -    */
 -   void open(const protocol_type& protocol = protocol_type())
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().open(impl_.get_implementation(), protocol, ec);
 -     asio::detail::throw_error(ec, "open");
 -   }
 - 
 -   /// Open the socket using the specified protocol.
 -   /**
 -    * This function opens the socket so that it will use the specified protocol.
 -    *
 -    * @param protocol An object specifying which protocol is to be used.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @par Example
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * asio::error_code ec;
 -    * socket.open(asio::ip::tcp::v4(), ec);
 -    * if (ec)
 -    * {
 -    *   // An error occurred.
 -    * }
 -    * @endcode
 -    */
 -   ASIO_SYNC_OP_VOID open(const protocol_type& protocol,
 -       asio::error_code& ec)
 -   {
 -     impl_.get_service().open(impl_.get_implementation(), protocol, ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Assign an existing native socket to the socket.
 -   /*
 -    * This function opens the socket to hold an existing native socket.
 -    *
 -    * @param protocol An object specifying which protocol is to be used.
 -    *
 -    * @param native_socket A native socket.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    */
 -   void assign(const protocol_type& protocol,
 -       const native_handle_type& native_socket)
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().assign(impl_.get_implementation(),
 -         protocol, native_socket, ec);
 -     asio::detail::throw_error(ec, "assign");
 -   }
 - 
 -   /// Assign an existing native socket to the socket.
 -   /*
 -    * This function opens the socket to hold an existing native socket.
 -    *
 -    * @param protocol An object specifying which protocol is to be used.
 -    *
 -    * @param native_socket A native socket.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    */
 -   ASIO_SYNC_OP_VOID assign(const protocol_type& protocol,
 -       const native_handle_type& native_socket, asio::error_code& ec)
 -   {
 -     impl_.get_service().assign(impl_.get_implementation(),
 -         protocol, native_socket, ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Determine whether the socket is open.
 -   bool is_open() const
 -   {
 -     return impl_.get_service().is_open(impl_.get_implementation());
 -   }
 - 
 -   /// Close the socket.
 -   /**
 -    * This function is used to close the socket. Any asynchronous send, receive
 -    * or connect operations will be cancelled immediately, and will complete
 -    * with the asio::error::operation_aborted error.
 -    *
 -    * @throws asio::system_error Thrown on failure. Note that, even if
 -    * the function indicates an error, the underlying descriptor is closed.
 -    *
 -    * @note For portable behaviour with respect to graceful closure of a
 -    * connected socket, call shutdown() before closing the socket.
 -    */
 -   void close()
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().close(impl_.get_implementation(), ec);
 -     asio::detail::throw_error(ec, "close");
 -   }
 - 
 -   /// Close the socket.
 -   /**
 -    * This function is used to close the socket. Any asynchronous send, receive
 -    * or connect operations will be cancelled immediately, and will complete
 -    * with the asio::error::operation_aborted error.
 -    *
 -    * @param ec Set to indicate what error occurred, if any. Note that, even if
 -    * the function indicates an error, the underlying descriptor is closed.
 -    *
 -    * @par Example
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::error_code ec;
 -    * socket.close(ec);
 -    * if (ec)
 -    * {
 -    *   // An error occurred.
 -    * }
 -    * @endcode
 -    *
 -    * @note For portable behaviour with respect to graceful closure of a
 -    * connected socket, call shutdown() before closing the socket.
 -    */
 -   ASIO_SYNC_OP_VOID close(asio::error_code& ec)
 -   {
 -     impl_.get_service().close(impl_.get_implementation(), ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Release ownership of the underlying native socket.
 -   /**
 -    * This function causes all outstanding asynchronous connect, send and receive
 -    * operations to finish immediately, and the handlers for cancelled operations
 -    * will be passed the asio::error::operation_aborted error. Ownership
 -    * of the native socket is then transferred to the caller.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    *
 -    * @note This function is unsupported on Windows versions prior to Windows
 -    * 8.1, and will fail with asio::error::operation_not_supported on
 -    * these platforms.
 -    */
 - #if defined(ASIO_MSVC) && (ASIO_MSVC >= 1400) \
 -   && (!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0603)
 -   __declspec(deprecated("This function always fails with "
 -         "operation_not_supported when used on Windows versions "
 -         "prior to Windows 8.1."))
 - #endif
 -   native_handle_type release()
 -   {
 -     asio::error_code ec;
 -     native_handle_type s = impl_.get_service().release(
 -         impl_.get_implementation(), ec);
 -     asio::detail::throw_error(ec, "release");
 -     return s;
 -   }
 - 
 -   /// Release ownership of the underlying native socket.
 -   /**
 -    * This function causes all outstanding asynchronous connect, send and receive
 -    * operations to finish immediately, and the handlers for cancelled operations
 -    * will be passed the asio::error::operation_aborted error. Ownership
 -    * of the native socket is then transferred to the caller.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @note This function is unsupported on Windows versions prior to Windows
 -    * 8.1, and will fail with asio::error::operation_not_supported on
 -    * these platforms.
 -    */
 - #if defined(ASIO_MSVC) && (ASIO_MSVC >= 1400) \
 -   && (!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0603)
 -   __declspec(deprecated("This function always fails with "
 -         "operation_not_supported when used on Windows versions "
 -         "prior to Windows 8.1."))
 - #endif
 -   native_handle_type release(asio::error_code& ec)
 -   {
 -     return impl_.get_service().release(impl_.get_implementation(), ec);
 -   }
 - 
 -   /// Get the native socket representation.
 -   /**
 -    * This function may be used to obtain the underlying representation of the
 -    * socket. This is intended to allow access to native socket functionality
 -    * that is not otherwise provided.
 -    */
 -   native_handle_type native_handle()
 -   {
 -     return impl_.get_service().native_handle(impl_.get_implementation());
 -   }
 - 
 -   /// Cancel all asynchronous operations associated with the socket.
 -   /**
 -    * This function causes all outstanding asynchronous connect, send and receive
 -    * operations to finish immediately, and the handlers for cancelled operations
 -    * will be passed the asio::error::operation_aborted error.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    *
 -    * @note Calls to cancel() will always fail with
 -    * asio::error::operation_not_supported when run on Windows XP, Windows
 -    * Server 2003, and earlier versions of Windows, unless
 -    * ASIO_ENABLE_CANCELIO is defined. However, the CancelIo function has
 -    * two issues that should be considered before enabling its use:
 -    *
 -    * @li It will only cancel asynchronous operations that were initiated in the
 -    * current thread.
 -    *
 -    * @li It can appear to complete without error, but the request to cancel the
 -    * unfinished operations may be silently ignored by the operating system.
 -    * Whether it works or not seems to depend on the drivers that are installed.
 -    *
 -    * For portable cancellation, consider using one of the following
 -    * alternatives:
 -    *
 -    * @li Disable asio's I/O completion port backend by defining
 -    * ASIO_DISABLE_IOCP.
 -    *
 -    * @li Use the close() function to simultaneously cancel the outstanding
 -    * operations and close the socket.
 -    *
 -    * When running on Windows Vista, Windows Server 2008, and later, the
 -    * CancelIoEx function is always used. This function does not have the
 -    * problems described above.
 -    */
 - #if defined(ASIO_MSVC) && (ASIO_MSVC >= 1400) \
 -   && (!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0600) \
 -   && !defined(ASIO_ENABLE_CANCELIO)
 -   __declspec(deprecated("By default, this function always fails with "
 -         "operation_not_supported when used on Windows XP, Windows Server 2003, "
 -         "or earlier. Consult documentation for details."))
 - #endif
 -   void cancel()
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().cancel(impl_.get_implementation(), ec);
 -     asio::detail::throw_error(ec, "cancel");
 -   }
 - 
 -   /// Cancel all asynchronous operations associated with the socket.
 -   /**
 -    * This function causes all outstanding asynchronous connect, send and receive
 -    * operations to finish immediately, and the handlers for cancelled operations
 -    * will be passed the asio::error::operation_aborted error.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @note Calls to cancel() will always fail with
 -    * asio::error::operation_not_supported when run on Windows XP, Windows
 -    * Server 2003, and earlier versions of Windows, unless
 -    * ASIO_ENABLE_CANCELIO is defined. However, the CancelIo function has
 -    * two issues that should be considered before enabling its use:
 -    *
 -    * @li It will only cancel asynchronous operations that were initiated in the
 -    * current thread.
 -    *
 -    * @li It can appear to complete without error, but the request to cancel the
 -    * unfinished operations may be silently ignored by the operating system.
 -    * Whether it works or not seems to depend on the drivers that are installed.
 -    *
 -    * For portable cancellation, consider using one of the following
 -    * alternatives:
 -    *
 -    * @li Disable asio's I/O completion port backend by defining
 -    * ASIO_DISABLE_IOCP.
 -    *
 -    * @li Use the close() function to simultaneously cancel the outstanding
 -    * operations and close the socket.
 -    *
 -    * When running on Windows Vista, Windows Server 2008, and later, the
 -    * CancelIoEx function is always used. This function does not have the
 -    * problems described above.
 -    */
 - #if defined(ASIO_MSVC) && (ASIO_MSVC >= 1400) \
 -   && (!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0600) \
 -   && !defined(ASIO_ENABLE_CANCELIO)
 -   __declspec(deprecated("By default, this function always fails with "
 -         "operation_not_supported when used on Windows XP, Windows Server 2003, "
 -         "or earlier. Consult documentation for details."))
 - #endif
 -   ASIO_SYNC_OP_VOID cancel(asio::error_code& ec)
 -   {
 -     impl_.get_service().cancel(impl_.get_implementation(), ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Determine whether the socket is at the out-of-band data mark.
 -   /**
 -    * This function is used to check whether the socket input is currently
 -    * positioned at the out-of-band data mark.
 -    *
 -    * @return A bool indicating whether the socket is at the out-of-band data
 -    * mark.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    */
 -   bool at_mark() const
 -   {
 -     asio::error_code ec;
 -     bool b = impl_.get_service().at_mark(impl_.get_implementation(), ec);
 -     asio::detail::throw_error(ec, "at_mark");
 -     return b;
 -   }
 - 
 -   /// Determine whether the socket is at the out-of-band data mark.
 -   /**
 -    * This function is used to check whether the socket input is currently
 -    * positioned at the out-of-band data mark.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @return A bool indicating whether the socket is at the out-of-band data
 -    * mark.
 -    */
 -   bool at_mark(asio::error_code& ec) const
 -   {
 -     return impl_.get_service().at_mark(impl_.get_implementation(), ec);
 -   }
 - 
 -   /// Determine the number of bytes available for reading.
 -   /**
 -    * This function is used to determine the number of bytes that may be read
 -    * without blocking.
 -    *
 -    * @return The number of bytes that may be read without blocking, or 0 if an
 -    * error occurs.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    */
 -   std::size_t available() const
 -   {
 -     asio::error_code ec;
 -     std::size_t s = impl_.get_service().available(
 -         impl_.get_implementation(), ec);
 -     asio::detail::throw_error(ec, "available");
 -     return s;
 -   }
 - 
 -   /// Determine the number of bytes available for reading.
 -   /**
 -    * This function is used to determine the number of bytes that may be read
 -    * without blocking.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @return The number of bytes that may be read without blocking, or 0 if an
 -    * error occurs.
 -    */
 -   std::size_t available(asio::error_code& ec) const
 -   {
 -     return impl_.get_service().available(impl_.get_implementation(), ec);
 -   }
 - 
 -   /// Bind the socket to the given local endpoint.
 -   /**
 -    * This function binds the socket to the specified endpoint on the local
 -    * machine.
 -    *
 -    * @param endpoint An endpoint on the local machine to which the socket will
 -    * be bound.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    *
 -    * @par Example
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * socket.open(asio::ip::tcp::v4());
 -    * socket.bind(asio::ip::tcp::endpoint(
 -    *       asio::ip::tcp::v4(), 12345));
 -    * @endcode
 -    */
 -   void bind(const endpoint_type& endpoint)
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().bind(impl_.get_implementation(), endpoint, ec);
 -     asio::detail::throw_error(ec, "bind");
 -   }
 - 
 -   /// Bind the socket to the given local endpoint.
 -   /**
 -    * This function binds the socket to the specified endpoint on the local
 -    * machine.
 -    *
 -    * @param endpoint An endpoint on the local machine to which the socket will
 -    * be bound.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @par Example
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * socket.open(asio::ip::tcp::v4());
 -    * asio::error_code ec;
 -    * socket.bind(asio::ip::tcp::endpoint(
 -    *       asio::ip::tcp::v4(), 12345), ec);
 -    * if (ec)
 -    * {
 -    *   // An error occurred.
 -    * }
 -    * @endcode
 -    */
 -   ASIO_SYNC_OP_VOID bind(const endpoint_type& endpoint,
 -       asio::error_code& ec)
 -   {
 -     impl_.get_service().bind(impl_.get_implementation(), endpoint, ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Connect the socket to the specified endpoint.
 -   /**
 -    * This function is used to connect a socket to the specified remote endpoint.
 -    * The function call will block until the connection is successfully made or
 -    * an error occurs.
 -    *
 -    * The socket is automatically opened if it is not already open. If the
 -    * connect fails, and the socket was automatically opened, the socket is
 -    * not returned to the closed state.
 -    *
 -    * @param peer_endpoint The remote endpoint to which the socket will be
 -    * connected.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    *
 -    * @par Example
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * asio::ip::tcp::endpoint endpoint(
 -    *     asio::ip::address::from_string("1.2.3.4"), 12345);
 -    * socket.connect(endpoint);
 -    * @endcode
 -    */
 -   void connect(const endpoint_type& peer_endpoint)
 -   {
 -     asio::error_code ec;
 -     if (!is_open())
 -     {
 -       impl_.get_service().open(impl_.get_implementation(),
 -           peer_endpoint.protocol(), ec);
 -       asio::detail::throw_error(ec, "connect");
 -     }
 -     impl_.get_service().connect(impl_.get_implementation(), peer_endpoint, ec);
 -     asio::detail::throw_error(ec, "connect");
 -   }
 - 
 -   /// Connect the socket to the specified endpoint.
 -   /**
 -    * This function is used to connect a socket to the specified remote endpoint.
 -    * The function call will block until the connection is successfully made or
 -    * an error occurs.
 -    *
 -    * The socket is automatically opened if it is not already open. If the
 -    * connect fails, and the socket was automatically opened, the socket is
 -    * not returned to the closed state.
 -    *
 -    * @param peer_endpoint The remote endpoint to which the socket will be
 -    * connected.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @par Example
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * asio::ip::tcp::endpoint endpoint(
 -    *     asio::ip::address::from_string("1.2.3.4"), 12345);
 -    * asio::error_code ec;
 -    * socket.connect(endpoint, ec);
 -    * if (ec)
 -    * {
 -    *   // An error occurred.
 -    * }
 -    * @endcode
 -    */
 -   ASIO_SYNC_OP_VOID connect(const endpoint_type& peer_endpoint,
 -       asio::error_code& ec)
 -   {
 -     if (!is_open())
 -     {
 -       impl_.get_service().open(impl_.get_implementation(),
 -             peer_endpoint.protocol(), ec);
 -       if (ec)
 -       {
 -         ASIO_SYNC_OP_VOID_RETURN(ec);
 -       }
 -     }
 - 
 -     impl_.get_service().connect(impl_.get_implementation(), peer_endpoint, ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Start an asynchronous connect.
 -   /**
 -    * This function is used to asynchronously connect a socket to the specified
 -    * remote endpoint. The function call always returns immediately.
 -    *
 -    * The socket is automatically opened if it is not already open. If the
 -    * connect fails, and the socket was automatically opened, the socket is
 -    * not returned to the closed state.
 -    *
 -    * @param peer_endpoint The remote endpoint to which the socket will be
 -    * connected. Copies will be made of the endpoint object as required.
 -    *
 -    * @param handler The handler to be called when the connection operation
 -    * completes. Copies will be made of the handler as required. The function
 -    * signature of the handler must be:
 -    * @code void handler(
 -    *   const asio::error_code& error // Result of operation
 -    * ); @endcode
 -    * Regardless of whether the asynchronous operation completes immediately or
 -    * not, the handler will not be invoked from within this function. On
 -    * immediate completion, invocation of the handler will be performed in a
 -    * manner equivalent to using asio::post().
 -    *
 -    * @par Example
 -    * @code
 -    * void connect_handler(const asio::error_code& error)
 -    * {
 -    *   if (!error)
 -    *   {
 -    *     // Connect succeeded.
 -    *   }
 -    * }
 -    *
 -    * ...
 -    *
 -    * asio::ip::tcp::socket socket(my_context);
 -    * asio::ip::tcp::endpoint endpoint(
 -    *     asio::ip::address::from_string("1.2.3.4"), 12345);
 -    * socket.async_connect(endpoint, connect_handler);
 -    * @endcode
 -    */
 -   template <typename ConnectHandler>
 -   ASIO_INITFN_RESULT_TYPE(ConnectHandler,
 -       void (asio::error_code))
 -   async_connect(const endpoint_type& peer_endpoint,
 -       ASIO_MOVE_ARG(ConnectHandler) handler)
 -   {
 -     asio::error_code open_ec;
 -     if (!is_open())
 -     {
 -       const protocol_type protocol = peer_endpoint.protocol();
 -       impl_.get_service().open(impl_.get_implementation(), protocol, open_ec);
 -     }
 - 
 -     return async_initiate<ConnectHandler, void (asio::error_code)>(
 -         initiate_async_connect(), handler, this, peer_endpoint, open_ec);
 -   }
 - 
 -   /// Set an option on the socket.
 -   /**
 -    * This function is used to set an option on the socket.
 -    *
 -    * @param option The new option value to be set on the socket.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    *
 -    * @sa SettableSocketOption @n
 -    * asio::socket_base::broadcast @n
 -    * asio::socket_base::do_not_route @n
 -    * asio::socket_base::keep_alive @n
 -    * asio::socket_base::linger @n
 -    * asio::socket_base::receive_buffer_size @n
 -    * asio::socket_base::receive_low_watermark @n
 -    * asio::socket_base::reuse_address @n
 -    * asio::socket_base::send_buffer_size @n
 -    * asio::socket_base::send_low_watermark @n
 -    * asio::ip::multicast::join_group @n
 -    * asio::ip::multicast::leave_group @n
 -    * asio::ip::multicast::enable_loopback @n
 -    * asio::ip::multicast::outbound_interface @n
 -    * asio::ip::multicast::hops @n
 -    * asio::ip::tcp::no_delay
 -    *
 -    * @par Example
 -    * Setting the IPPROTO_TCP/TCP_NODELAY option:
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::ip::tcp::no_delay option(true);
 -    * socket.set_option(option);
 -    * @endcode
 -    */
 -   template <typename SettableSocketOption>
 -   void set_option(const SettableSocketOption& option)
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().set_option(impl_.get_implementation(), option, ec);
 -     asio::detail::throw_error(ec, "set_option");
 -   }
 - 
 -   /// Set an option on the socket.
 -   /**
 -    * This function is used to set an option on the socket.
 -    *
 -    * @param option The new option value to be set on the socket.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @sa SettableSocketOption @n
 -    * asio::socket_base::broadcast @n
 -    * asio::socket_base::do_not_route @n
 -    * asio::socket_base::keep_alive @n
 -    * asio::socket_base::linger @n
 -    * asio::socket_base::receive_buffer_size @n
 -    * asio::socket_base::receive_low_watermark @n
 -    * asio::socket_base::reuse_address @n
 -    * asio::socket_base::send_buffer_size @n
 -    * asio::socket_base::send_low_watermark @n
 -    * asio::ip::multicast::join_group @n
 -    * asio::ip::multicast::leave_group @n
 -    * asio::ip::multicast::enable_loopback @n
 -    * asio::ip::multicast::outbound_interface @n
 -    * asio::ip::multicast::hops @n
 -    * asio::ip::tcp::no_delay
 -    *
 -    * @par Example
 -    * Setting the IPPROTO_TCP/TCP_NODELAY option:
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::ip::tcp::no_delay option(true);
 -    * asio::error_code ec;
 -    * socket.set_option(option, ec);
 -    * if (ec)
 -    * {
 -    *   // An error occurred.
 -    * }
 -    * @endcode
 -    */
 -   template <typename SettableSocketOption>
 -   ASIO_SYNC_OP_VOID set_option(const SettableSocketOption& option,
 -       asio::error_code& ec)
 -   {
 -     impl_.get_service().set_option(impl_.get_implementation(), option, ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Get an option from the socket.
 -   /**
 -    * This function is used to get the current value of an option on the socket.
 -    *
 -    * @param option The option value to be obtained from the socket.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    *
 -    * @sa GettableSocketOption @n
 -    * asio::socket_base::broadcast @n
 -    * asio::socket_base::do_not_route @n
 -    * asio::socket_base::keep_alive @n
 -    * asio::socket_base::linger @n
 -    * asio::socket_base::receive_buffer_size @n
 -    * asio::socket_base::receive_low_watermark @n
 -    * asio::socket_base::reuse_address @n
 -    * asio::socket_base::send_buffer_size @n
 -    * asio::socket_base::send_low_watermark @n
 -    * asio::ip::multicast::join_group @n
 -    * asio::ip::multicast::leave_group @n
 -    * asio::ip::multicast::enable_loopback @n
 -    * asio::ip::multicast::outbound_interface @n
 -    * asio::ip::multicast::hops @n
 -    * asio::ip::tcp::no_delay
 -    *
 -    * @par Example
 -    * Getting the value of the SOL_SOCKET/SO_KEEPALIVE option:
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::ip::tcp::socket::keep_alive option;
 -    * socket.get_option(option);
 -    * bool is_set = option.value();
 -    * @endcode
 -    */
 -   template <typename GettableSocketOption>
 -   void get_option(GettableSocketOption& option) const
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().get_option(impl_.get_implementation(), option, ec);
 -     asio::detail::throw_error(ec, "get_option");
 -   }
 - 
 -   /// Get an option from the socket.
 -   /**
 -    * This function is used to get the current value of an option on the socket.
 -    *
 -    * @param option The option value to be obtained from the socket.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @sa GettableSocketOption @n
 -    * asio::socket_base::broadcast @n
 -    * asio::socket_base::do_not_route @n
 -    * asio::socket_base::keep_alive @n
 -    * asio::socket_base::linger @n
 -    * asio::socket_base::receive_buffer_size @n
 -    * asio::socket_base::receive_low_watermark @n
 -    * asio::socket_base::reuse_address @n
 -    * asio::socket_base::send_buffer_size @n
 -    * asio::socket_base::send_low_watermark @n
 -    * asio::ip::multicast::join_group @n
 -    * asio::ip::multicast::leave_group @n
 -    * asio::ip::multicast::enable_loopback @n
 -    * asio::ip::multicast::outbound_interface @n
 -    * asio::ip::multicast::hops @n
 -    * asio::ip::tcp::no_delay
 -    *
 -    * @par Example
 -    * Getting the value of the SOL_SOCKET/SO_KEEPALIVE option:
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::ip::tcp::socket::keep_alive option;
 -    * asio::error_code ec;
 -    * socket.get_option(option, ec);
 -    * if (ec)
 -    * {
 -    *   // An error occurred.
 -    * }
 -    * bool is_set = option.value();
 -    * @endcode
 -    */
 -   template <typename GettableSocketOption>
 -   ASIO_SYNC_OP_VOID get_option(GettableSocketOption& option,
 -       asio::error_code& ec) const
 -   {
 -     impl_.get_service().get_option(impl_.get_implementation(), option, ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Perform an IO control command on the socket.
 -   /**
 -    * This function is used to execute an IO control command on the socket.
 -    *
 -    * @param command The IO control command to be performed on the socket.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    *
 -    * @sa IoControlCommand @n
 -    * asio::socket_base::bytes_readable @n
 -    * asio::socket_base::non_blocking_io
 -    *
 -    * @par Example
 -    * Getting the number of bytes ready to read:
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::ip::tcp::socket::bytes_readable command;
 -    * socket.io_control(command);
 -    * std::size_t bytes_readable = command.get();
 -    * @endcode
 -    */
 -   template <typename IoControlCommand>
 -   void io_control(IoControlCommand& command)
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().io_control(impl_.get_implementation(), command, ec);
 -     asio::detail::throw_error(ec, "io_control");
 -   }
 - 
 -   /// Perform an IO control command on the socket.
 -   /**
 -    * This function is used to execute an IO control command on the socket.
 -    *
 -    * @param command The IO control command to be performed on the socket.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @sa IoControlCommand @n
 -    * asio::socket_base::bytes_readable @n
 -    * asio::socket_base::non_blocking_io
 -    *
 -    * @par Example
 -    * Getting the number of bytes ready to read:
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::ip::tcp::socket::bytes_readable command;
 -    * asio::error_code ec;
 -    * socket.io_control(command, ec);
 -    * if (ec)
 -    * {
 -    *   // An error occurred.
 -    * }
 -    * std::size_t bytes_readable = command.get();
 -    * @endcode
 -    */
 -   template <typename IoControlCommand>
 -   ASIO_SYNC_OP_VOID io_control(IoControlCommand& command,
 -       asio::error_code& ec)
 -   {
 -     impl_.get_service().io_control(impl_.get_implementation(), command, ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Gets the non-blocking mode of the socket.
 -   /**
 -    * @returns @c true if the socket's synchronous operations will fail with
 -    * asio::error::would_block if they are unable to perform the requested
 -    * operation immediately. If @c false, synchronous operations will block
 -    * until complete.
 -    *
 -    * @note The non-blocking mode has no effect on the behaviour of asynchronous
 -    * operations. Asynchronous operations will never fail with the error
 -    * asio::error::would_block.
 -    */
 -   bool non_blocking() const
 -   {
 -     return impl_.get_service().non_blocking(impl_.get_implementation());
 -   }
 - 
 -   /// Sets the non-blocking mode of the socket.
 -   /**
 -    * @param mode If @c true, the socket's synchronous operations will fail with
 -    * asio::error::would_block if they are unable to perform the requested
 -    * operation immediately. If @c false, synchronous operations will block
 -    * until complete.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    *
 -    * @note The non-blocking mode has no effect on the behaviour of asynchronous
 -    * operations. Asynchronous operations will never fail with the error
 -    * asio::error::would_block.
 -    */
 -   void non_blocking(bool mode)
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().non_blocking(impl_.get_implementation(), mode, ec);
 -     asio::detail::throw_error(ec, "non_blocking");
 -   }
 - 
 -   /// Sets the non-blocking mode of the socket.
 -   /**
 -    * @param mode If @c true, the socket's synchronous operations will fail with
 -    * asio::error::would_block if they are unable to perform the requested
 -    * operation immediately. If @c false, synchronous operations will block
 -    * until complete.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @note The non-blocking mode has no effect on the behaviour of asynchronous
 -    * operations. Asynchronous operations will never fail with the error
 -    * asio::error::would_block.
 -    */
 -   ASIO_SYNC_OP_VOID non_blocking(
 -       bool mode, asio::error_code& ec)
 -   {
 -     impl_.get_service().non_blocking(impl_.get_implementation(), mode, ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Gets the non-blocking mode of the native socket implementation.
 -   /**
 -    * This function is used to retrieve the non-blocking mode of the underlying
 -    * native socket. This mode has no effect on the behaviour of the socket
 -    * object's synchronous operations.
 -    *
 -    * @returns @c true if the underlying socket is in non-blocking mode and
 -    * direct system calls may fail with asio::error::would_block (or the
 -    * equivalent system error).
 -    *
 -    * @note The current non-blocking mode is cached by the socket object.
 -    * Consequently, the return value may be incorrect if the non-blocking mode
 -    * was set directly on the native socket.
 -    *
 -    * @par Example
 -    * This function is intended to allow the encapsulation of arbitrary
 -    * non-blocking system calls as asynchronous operations, in a way that is
 -    * transparent to the user of the socket object. The following example
 -    * illustrates how Linux's @c sendfile system call might be encapsulated:
 -    * @code template <typename Handler>
 -    * struct sendfile_op
 -    * {
 -    *   tcp::socket& sock_;
 -    *   int fd_;
 -    *   Handler handler_;
 -    *   off_t offset_;
 -    *   std::size_t total_bytes_transferred_;
 -    *
 -    *   // Function call operator meeting WriteHandler requirements.
 -    *   // Used as the handler for the async_write_some operation.
 -    *   void operator()(asio::error_code ec, std::size_t)
 -    *   {
 -    *     // Put the underlying socket into non-blocking mode.
 -    *     if (!ec)
 -    *       if (!sock_.native_non_blocking())
 -    *         sock_.native_non_blocking(true, ec);
 -    *
 -    *     if (!ec)
 -    *     {
 -    *       for (;;)
 -    *       {
 -    *         // Try the system call.
 -    *         errno = 0;
 -    *         int n = ::sendfile(sock_.native_handle(), fd_, &offset_, 65536);
 -    *         ec = asio::error_code(n < 0 ? errno : 0,
 -    *             asio::error::get_system_category());
 -    *         total_bytes_transferred_ += ec ? 0 : n;
 -    *
 -    *         // Retry operation immediately if interrupted by signal.
 -    *         if (ec == asio::error::interrupted)
 -    *           continue;
 -    *
 -    *         // Check if we need to run the operation again.
 -    *         if (ec == asio::error::would_block
 -    *             || ec == asio::error::try_again)
 -    *         {
 -    *           // We have to wait for the socket to become ready again.
 -    *           sock_.async_wait(tcp::socket::wait_write, *this);
 -    *           return;
 -    *         }
 -    *
 -    *         if (ec || n == 0)
 -    *         {
 -    *           // An error occurred, or we have reached the end of the file.
 -    *           // Either way we must exit the loop so we can call the handler.
 -    *           break;
 -    *         }
 -    *
 -    *         // Loop around to try calling sendfile again.
 -    *       }
 -    *     }
 -    *
 -    *     // Pass result back to user's handler.
 -    *     handler_(ec, total_bytes_transferred_);
 -    *   }
 -    * };
 -    *
 -    * template <typename Handler>
 -    * void async_sendfile(tcp::socket& sock, int fd, Handler h)
 -    * {
 -    *   sendfile_op<Handler> op = { sock, fd, h, 0, 0 };
 -    *   sock.async_wait(tcp::socket::wait_write, op);
 -    * } @endcode
 -    */
 -   bool native_non_blocking() const
 -   {
 -     return impl_.get_service().native_non_blocking(impl_.get_implementation());
 -   }
 - 
 -   /// Sets the non-blocking mode of the native socket implementation.
 -   /**
 -    * This function is used to modify the non-blocking mode of the underlying
 -    * native socket. It has no effect on the behaviour of the socket object's
 -    * synchronous operations.
 -    *
 -    * @param mode If @c true, the underlying socket is put into non-blocking
 -    * mode and direct system calls may fail with asio::error::would_block
 -    * (or the equivalent system error).
 -    *
 -    * @throws asio::system_error Thrown on failure. If the @c mode is
 -    * @c false, but the current value of @c non_blocking() is @c true, this
 -    * function fails with asio::error::invalid_argument, as the
 -    * combination does not make sense.
 -    *
 -    * @par Example
 -    * This function is intended to allow the encapsulation of arbitrary
 -    * non-blocking system calls as asynchronous operations, in a way that is
 -    * transparent to the user of the socket object. The following example
 -    * illustrates how Linux's @c sendfile system call might be encapsulated:
 -    * @code template <typename Handler>
 -    * struct sendfile_op
 -    * {
 -    *   tcp::socket& sock_;
 -    *   int fd_;
 -    *   Handler handler_;
 -    *   off_t offset_;
 -    *   std::size_t total_bytes_transferred_;
 -    *
 -    *   // Function call operator meeting WriteHandler requirements.
 -    *   // Used as the handler for the async_write_some operation.
 -    *   void operator()(asio::error_code ec, std::size_t)
 -    *   {
 -    *     // Put the underlying socket into non-blocking mode.
 -    *     if (!ec)
 -    *       if (!sock_.native_non_blocking())
 -    *         sock_.native_non_blocking(true, ec);
 -    *
 -    *     if (!ec)
 -    *     {
 -    *       for (;;)
 -    *       {
 -    *         // Try the system call.
 -    *         errno = 0;
 -    *         int n = ::sendfile(sock_.native_handle(), fd_, &offset_, 65536);
 -    *         ec = asio::error_code(n < 0 ? errno : 0,
 -    *             asio::error::get_system_category());
 -    *         total_bytes_transferred_ += ec ? 0 : n;
 -    *
 -    *         // Retry operation immediately if interrupted by signal.
 -    *         if (ec == asio::error::interrupted)
 -    *           continue;
 -    *
 -    *         // Check if we need to run the operation again.
 -    *         if (ec == asio::error::would_block
 -    *             || ec == asio::error::try_again)
 -    *         {
 -    *           // We have to wait for the socket to become ready again.
 -    *           sock_.async_wait(tcp::socket::wait_write, *this);
 -    *           return;
 -    *         }
 -    *
 -    *         if (ec || n == 0)
 -    *         {
 -    *           // An error occurred, or we have reached the end of the file.
 -    *           // Either way we must exit the loop so we can call the handler.
 -    *           break;
 -    *         }
 -    *
 -    *         // Loop around to try calling sendfile again.
 -    *       }
 -    *     }
 -    *
 -    *     // Pass result back to user's handler.
 -    *     handler_(ec, total_bytes_transferred_);
 -    *   }
 -    * };
 -    *
 -    * template <typename Handler>
 -    * void async_sendfile(tcp::socket& sock, int fd, Handler h)
 -    * {
 -    *   sendfile_op<Handler> op = { sock, fd, h, 0, 0 };
 -    *   sock.async_wait(tcp::socket::wait_write, op);
 -    * } @endcode
 -    */
 -   void native_non_blocking(bool mode)
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().native_non_blocking(
 -         impl_.get_implementation(), mode, ec);
 -     asio::detail::throw_error(ec, "native_non_blocking");
 -   }
 - 
 -   /// Sets the non-blocking mode of the native socket implementation.
 -   /**
 -    * This function is used to modify the non-blocking mode of the underlying
 -    * native socket. It has no effect on the behaviour of the socket object's
 -    * synchronous operations.
 -    *
 -    * @param mode If @c true, the underlying socket is put into non-blocking
 -    * mode and direct system calls may fail with asio::error::would_block
 -    * (or the equivalent system error).
 -    *
 -    * @param ec Set to indicate what error occurred, if any. If the @c mode is
 -    * @c false, but the current value of @c non_blocking() is @c true, this
 -    * function fails with asio::error::invalid_argument, as the
 -    * combination does not make sense.
 -    *
 -    * @par Example
 -    * This function is intended to allow the encapsulation of arbitrary
 -    * non-blocking system calls as asynchronous operations, in a way that is
 -    * transparent to the user of the socket object. The following example
 -    * illustrates how Linux's @c sendfile system call might be encapsulated:
 -    * @code template <typename Handler>
 -    * struct sendfile_op
 -    * {
 -    *   tcp::socket& sock_;
 -    *   int fd_;
 -    *   Handler handler_;
 -    *   off_t offset_;
 -    *   std::size_t total_bytes_transferred_;
 -    *
 -    *   // Function call operator meeting WriteHandler requirements.
 -    *   // Used as the handler for the async_write_some operation.
 -    *   void operator()(asio::error_code ec, std::size_t)
 -    *   {
 -    *     // Put the underlying socket into non-blocking mode.
 -    *     if (!ec)
 -    *       if (!sock_.native_non_blocking())
 -    *         sock_.native_non_blocking(true, ec);
 -    *
 -    *     if (!ec)
 -    *     {
 -    *       for (;;)
 -    *       {
 -    *         // Try the system call.
 -    *         errno = 0;
 -    *         int n = ::sendfile(sock_.native_handle(), fd_, &offset_, 65536);
 -    *         ec = asio::error_code(n < 0 ? errno : 0,
 -    *             asio::error::get_system_category());
 -    *         total_bytes_transferred_ += ec ? 0 : n;
 -    *
 -    *         // Retry operation immediately if interrupted by signal.
 -    *         if (ec == asio::error::interrupted)
 -    *           continue;
 -    *
 -    *         // Check if we need to run the operation again.
 -    *         if (ec == asio::error::would_block
 -    *             || ec == asio::error::try_again)
 -    *         {
 -    *           // We have to wait for the socket to become ready again.
 -    *           sock_.async_wait(tcp::socket::wait_write, *this);
 -    *           return;
 -    *         }
 -    *
 -    *         if (ec || n == 0)
 -    *         {
 -    *           // An error occurred, or we have reached the end of the file.
 -    *           // Either way we must exit the loop so we can call the handler.
 -    *           break;
 -    *         }
 -    *
 -    *         // Loop around to try calling sendfile again.
 -    *       }
 -    *     }
 -    *
 -    *     // Pass result back to user's handler.
 -    *     handler_(ec, total_bytes_transferred_);
 -    *   }
 -    * };
 -    *
 -    * template <typename Handler>
 -    * void async_sendfile(tcp::socket& sock, int fd, Handler h)
 -    * {
 -    *   sendfile_op<Handler> op = { sock, fd, h, 0, 0 };
 -    *   sock.async_wait(tcp::socket::wait_write, op);
 -    * } @endcode
 -    */
 -   ASIO_SYNC_OP_VOID native_non_blocking(
 -       bool mode, asio::error_code& ec)
 -   {
 -     impl_.get_service().native_non_blocking(
 -         impl_.get_implementation(), mode, ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Get the local endpoint of the socket.
 -   /**
 -    * This function is used to obtain the locally bound endpoint of the socket.
 -    *
 -    * @returns An object that represents the local endpoint of the socket.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    *
 -    * @par Example
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::ip::tcp::endpoint endpoint = socket.local_endpoint();
 -    * @endcode
 -    */
 -   endpoint_type local_endpoint() const
 -   {
 -     asio::error_code ec;
 -     endpoint_type ep = impl_.get_service().local_endpoint(
 -         impl_.get_implementation(), ec);
 -     asio::detail::throw_error(ec, "local_endpoint");
 -     return ep;
 -   }
 - 
 -   /// Get the local endpoint of the socket.
 -   /**
 -    * This function is used to obtain the locally bound endpoint of the socket.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @returns An object that represents the local endpoint of the socket.
 -    * Returns a default-constructed endpoint object if an error occurred.
 -    *
 -    * @par Example
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::error_code ec;
 -    * asio::ip::tcp::endpoint endpoint = socket.local_endpoint(ec);
 -    * if (ec)
 -    * {
 -    *   // An error occurred.
 -    * }
 -    * @endcode
 -    */
 -   endpoint_type local_endpoint(asio::error_code& ec) const
 -   {
 -     return impl_.get_service().local_endpoint(impl_.get_implementation(), ec);
 -   }
 - 
 -   /// Get the remote endpoint of the socket.
 -   /**
 -    * This function is used to obtain the remote endpoint of the socket.
 -    *
 -    * @returns An object that represents the remote endpoint of the socket.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    *
 -    * @par Example
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::ip::tcp::endpoint endpoint = socket.remote_endpoint();
 -    * @endcode
 -    */
 -   endpoint_type remote_endpoint() const
 -   {
 -     asio::error_code ec;
 -     endpoint_type ep = impl_.get_service().remote_endpoint(
 -         impl_.get_implementation(), ec);
 -     asio::detail::throw_error(ec, "remote_endpoint");
 -     return ep;
 -   }
 - 
 -   /// Get the remote endpoint of the socket.
 -   /**
 -    * This function is used to obtain the remote endpoint of the socket.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @returns An object that represents the remote endpoint of the socket.
 -    * Returns a default-constructed endpoint object if an error occurred.
 -    *
 -    * @par Example
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::error_code ec;
 -    * asio::ip::tcp::endpoint endpoint = socket.remote_endpoint(ec);
 -    * if (ec)
 -    * {
 -    *   // An error occurred.
 -    * }
 -    * @endcode
 -    */
 -   endpoint_type remote_endpoint(asio::error_code& ec) const
 -   {
 -     return impl_.get_service().remote_endpoint(impl_.get_implementation(), ec);
 -   }
 - 
 -   /// Disable sends or receives on the socket.
 -   /**
 -    * This function is used to disable send operations, receive operations, or
 -    * both.
 -    *
 -    * @param what Determines what types of operation will no longer be allowed.
 -    *
 -    * @throws asio::system_error Thrown on failure.
 -    *
 -    * @par Example
 -    * Shutting down the send side of the socket:
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * socket.shutdown(asio::ip::tcp::socket::shutdown_send);
 -    * @endcode
 -    */
 -   void shutdown(shutdown_type what)
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().shutdown(impl_.get_implementation(), what, ec);
 -     asio::detail::throw_error(ec, "shutdown");
 -   }
 - 
 -   /// Disable sends or receives on the socket.
 -   /**
 -    * This function is used to disable send operations, receive operations, or
 -    * both.
 -    *
 -    * @param what Determines what types of operation will no longer be allowed.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @par Example
 -    * Shutting down the send side of the socket:
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::error_code ec;
 -    * socket.shutdown(asio::ip::tcp::socket::shutdown_send, ec);
 -    * if (ec)
 -    * {
 -    *   // An error occurred.
 -    * }
 -    * @endcode
 -    */
 -   ASIO_SYNC_OP_VOID shutdown(shutdown_type what,
 -       asio::error_code& ec)
 -   {
 -     impl_.get_service().shutdown(impl_.get_implementation(), what, ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Wait for the socket to become ready to read, ready to write, or to have
 -   /// pending error conditions.
 -   /**
 -    * This function is used to perform a blocking wait for a socket to enter
 -    * a ready to read, write or error condition state.
 -    *
 -    * @param w Specifies the desired socket state.
 -    *
 -    * @par Example
 -    * Waiting for a socket to become readable.
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * socket.wait(asio::ip::tcp::socket::wait_read);
 -    * @endcode
 -    */
 -   void wait(wait_type w)
 -   {
 -     asio::error_code ec;
 -     impl_.get_service().wait(impl_.get_implementation(), w, ec);
 -     asio::detail::throw_error(ec, "wait");
 -   }
 - 
 -   /// Wait for the socket to become ready to read, ready to write, or to have
 -   /// pending error conditions.
 -   /**
 -    * This function is used to perform a blocking wait for a socket to enter
 -    * a ready to read, write or error condition state.
 -    *
 -    * @param w Specifies the desired socket state.
 -    *
 -    * @param ec Set to indicate what error occurred, if any.
 -    *
 -    * @par Example
 -    * Waiting for a socket to become readable.
 -    * @code
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * asio::error_code ec;
 -    * socket.wait(asio::ip::tcp::socket::wait_read, ec);
 -    * @endcode
 -    */
 -   ASIO_SYNC_OP_VOID wait(wait_type w, asio::error_code& ec)
 -   {
 -     impl_.get_service().wait(impl_.get_implementation(), w, ec);
 -     ASIO_SYNC_OP_VOID_RETURN(ec);
 -   }
 - 
 -   /// Asynchronously wait for the socket to become ready to read, ready to
 -   /// write, or to have pending error conditions.
 -   /**
 -    * This function is used to perform an asynchronous wait for a socket to enter
 -    * a ready to read, write or error condition state.
 -    *
 -    * @param w Specifies the desired socket state.
 -    *
 -    * @param handler The handler to be called when the wait operation completes.
 -    * Copies will be made of the handler as required. The function signature of
 -    * the handler must be:
 -    * @code void handler(
 -    *   const asio::error_code& error // Result of operation
 -    * ); @endcode
 -    * Regardless of whether the asynchronous operation completes immediately or
 -    * not, the handler will not be invoked from within this function. On
 -    * immediate completion, invocation of the handler will be performed in a
 -    * manner equivalent to using asio::post().
 -    *
 -    * @par Example
 -    * @code
 -    * void wait_handler(const asio::error_code& error)
 -    * {
 -    *   if (!error)
 -    *   {
 -    *     // Wait succeeded.
 -    *   }
 -    * }
 -    *
 -    * ...
 -    *
 -    * asio::ip::tcp::socket socket(my_context);
 -    * ...
 -    * socket.async_wait(asio::ip::tcp::socket::wait_read, wait_handler);
 -    * @endcode
 -    */
 -   template <typename WaitHandler>
 -   ASIO_INITFN_RESULT_TYPE(WaitHandler,
 -       void (asio::error_code))
 -   async_wait(wait_type w, ASIO_MOVE_ARG(WaitHandler) handler)
 -   {
 -     return async_initiate<WaitHandler, void (asio::error_code)>(
 -         initiate_async_wait(), handler, this, w);
 -   }
 - 
 - protected:
 -   /// Protected destructor to prevent deletion through this type.
 -   /**
 -    * This function destroys the socket, cancelling any outstanding asynchronous
 -    * operations associated with the socket as if by calling @c cancel.
 -    */
 -   ~basic_socket()
 -   {
 -   }
 - 
 - #if defined(ASIO_WINDOWS_RUNTIME)
 -   detail::io_object_impl<
 -     detail::null_socket_service<Protocol>, Executor> impl_;
 - #elif defined(ASIO_HAS_IOCP)
 -   detail::io_object_impl<
 -     detail::win_iocp_socket_service<Protocol>, Executor> impl_;
 - #else
 -   detail::io_object_impl<
 -     detail::reactive_socket_service<Protocol>, Executor> impl_;
 - #endif
 - 
 - private:
 -   // Disallow copying and assignment.
 -   basic_socket(const basic_socket&) ASIO_DELETED;
 -   basic_socket& operator=(const basic_socket&) ASIO_DELETED;
 - 
 -   struct initiate_async_connect
 -   {
 -     template <typename ConnectHandler>
 -     void operator()(ASIO_MOVE_ARG(ConnectHandler) handler,
 -         basic_socket* self, const endpoint_type& peer_endpoint,
 -         const asio::error_code& open_ec) const
 -     {
 -       // If you get an error on the following line it means that your handler
 -       // does not meet the documented type requirements for a ConnectHandler.
 -       ASIO_CONNECT_HANDLER_CHECK(ConnectHandler, handler) type_check;
 - 
 -       if (open_ec)
 -       {
 -           asio::post(self->impl_.get_executor(),
 -               asio::detail::bind_handler(
 -                 ASIO_MOVE_CAST(ConnectHandler)(handler), open_ec));
 -       }
 -       else
 -       {
 -         detail::non_const_lvalue<ConnectHandler> handler2(handler);
 -         self->impl_.get_service().async_connect(
 -             self->impl_.get_implementation(), peer_endpoint,
 -             handler2.value, self->impl_.get_implementation_executor());
 -       }
 -     }
 -   };
 - 
 -   struct initiate_async_wait
 -   {
 -     template <typename WaitHandler>
 -     void operator()(ASIO_MOVE_ARG(WaitHandler) handler,
 -         basic_socket* self, wait_type w) const
 -     {
 -       // If you get an error on the following line it means that your handler
 -       // does not meet the documented type requirements for a WaitHandler.
 -       ASIO_WAIT_HANDLER_CHECK(WaitHandler, handler) type_check;
 - 
 -       detail::non_const_lvalue<WaitHandler> handler2(handler);
 -       self->impl_.get_service().async_wait(
 -           self->impl_.get_implementation(), w, handler2.value,
 -           self->impl_.get_implementation_executor());
 -     }
 -   };
 - };
 - 
 - } // namespace asio
 - 
 - #include "asio/detail/pop_options.hpp"
 - 
 - #endif // ASIO_BASIC_SOCKET_HPP
 
 
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