EIC code displayed by LXR master/​include/​boost/​asio/​basic_socket.hpp	Source navigation Diff markup Identifier search General search
	Version: master test Revert   Change

File indexing completed on 2025-01-18 09:29:05

 //
 // basic_socket.hpp
 // ~~~~~~~~~~~~~~~~
 //
 // Copyright (c) 2003-2023 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 BOOST_ASIO_BASIC_SOCKET_HPP
 #define BOOST_ASIO_BASIC_SOCKET_HPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <utility>
 #include <boost/asio/any_io_executor.hpp>
 #include <boost/asio/detail/config.hpp>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/handler_type_requirements.hpp>
 #include <boost/asio/detail/io_object_impl.hpp>
 #include <boost/asio/detail/non_const_lvalue.hpp>
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
 #include <boost/asio/execution_context.hpp>
 #include <boost/asio/post.hpp>
 #include <boost/asio/socket_base.hpp>
 
 #if defined(BOOST_ASIO_WINDOWS_RUNTIME)
 # include <boost/asio/detail/null_socket_service.hpp>
 #elif defined(BOOST_ASIO_HAS_IOCP)
 # include <boost/asio/detail/win_iocp_socket_service.hpp>
 #elif defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
 # include <boost/asio/detail/io_uring_socket_service.hpp>
 #else
 # include <boost/asio/detail/reactive_socket_service.hpp>
 #endif
 
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 
 #if !defined(BOOST_ASIO_BASIC_SOCKET_FWD_DECL)
 #define BOOST_ASIO_BASIC_SOCKET_FWD_DECL
 
 // Forward declaration with defaulted arguments.
 template <typename Protocol, typename Executor = any_io_executor>
 class basic_socket;
 
 #endif // !defined(BOOST_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
 {
 private:
   class initiate_async_connect;
   class initiate_async_wait;
 
 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(BOOST_ASIO_WINDOWS_RUNTIME)
   typedef typename detail::null_socket_service<
     Protocol>::native_handle_type native_handle_type;
 #elif defined(BOOST_ASIO_HAS_IOCP)
   typedef typename detail::win_iocp_socket_service<
     Protocol>::native_handle_type native_handle_type;
 #elif defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
   typedef typename detail::io_uring_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(BOOST_ASIO_NO_EXTENSIONS)
   /// A basic_socket is always the lowest layer.
   typedef basic_socket<Protocol, Executor> lowest_layer_type;
 #endif // !defined(BOOST_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_(0, 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,
       constraint_t<
         is_convertible<ExecutionContext&, execution_context&>::value
       > = 0)
     : impl_(0, 0, 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 boost::system::system_error Thrown on failure.
    */
   basic_socket(const executor_type& ex, const protocol_type& protocol)
     : impl_(0, ex)
   {
     boost::system::error_code ec;
     impl_.get_service().open(impl_.get_implementation(), protocol, ec);
     boost::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 boost::system::system_error Thrown on failure.
    */
   template <typename ExecutionContext>
   basic_socket(ExecutionContext& context, const protocol_type& protocol,
       constraint_t<
         is_convertible<ExecutionContext&, execution_context&>::value,
         defaulted_constraint
       > = defaulted_constraint())
     : impl_(0, 0, context)
   {
     boost::system::error_code ec;
     impl_.get_service().open(impl_.get_implementation(), protocol, ec);
     boost::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 boost::system::system_error Thrown on failure.
    */
   basic_socket(const executor_type& ex, const endpoint_type& endpoint)
     : impl_(0, ex)
   {
     boost::system::error_code ec;
     const protocol_type protocol = endpoint.protocol();
     impl_.get_service().open(impl_.get_implementation(), protocol, ec);
     boost::asio::detail::throw_error(ec, "open");
     impl_.get_service().bind(impl_.get_implementation(), endpoint, ec);
     boost::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 boost::system::system_error Thrown on failure.
    */
   template <typename ExecutionContext>
   basic_socket(ExecutionContext& context, const endpoint_type& endpoint,
       constraint_t<
         is_convertible<ExecutionContext&, execution_context&>::value
       > = 0)
     : impl_(0, 0, context)
   {
     boost::system::error_code ec;
     const protocol_type protocol = endpoint.protocol();
     impl_.get_service().open(impl_.get_implementation(), protocol, ec);
     boost::asio::detail::throw_error(ec, "open");
     impl_.get_service().bind(impl_.get_implementation(), endpoint, ec);
     boost::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 boost::system::system_error Thrown on failure.
    */
   basic_socket(const executor_type& ex, const protocol_type& protocol,
       const native_handle_type& native_socket)
     : impl_(0, ex)
   {
     boost::system::error_code ec;
     impl_.get_service().assign(impl_.get_implementation(),
         protocol, native_socket, ec);
     boost::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 boost::system::system_error Thrown on failure.
    */
   template <typename ExecutionContext>
   basic_socket(ExecutionContext& context, const protocol_type& protocol,
       const native_handle_type& native_socket,
       constraint_t<
         is_convertible<ExecutionContext&, execution_context&>::value
       > = 0)
     : impl_(0, 0, context)
   {
     boost::system::error_code ec;
     impl_.get_service().assign(impl_.get_implementation(),
         protocol, native_socket, ec);
     boost::asio::detail::throw_error(ec, "assign");
   }
 
   /// 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) noexcept
     : 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,
       constraint_t<
         is_convertible<Protocol1, Protocol>::value
           && is_convertible<Executor1, Executor>::value
       > = 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>
   constraint_t<
     is_convertible<Protocol1, Protocol>::value
       && is_convertible<Executor1, Executor>::value,
     basic_socket&
   > operator=(basic_socket<Protocol1, Executor1>&& other)
   {
     basic_socket tmp(std::move(other));
     impl_ = std::move(tmp.impl_);
     return *this;
   }
 
   /// Get the executor associated with the object.
   const executor_type& get_executor() noexcept
   {
     return impl_.get_executor();
   }
 
 #if !defined(BOOST_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(BOOST_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 boost::system::system_error Thrown on failure.
    *
    * @par Example
    * @code
    * boost::asio::ip::tcp::socket socket(my_context);
    * socket.open(boost::asio::ip::tcp::v4());
    * @endcode
    */
   void open(const protocol_type& protocol = protocol_type())
   {
     boost::system::error_code ec;
     impl_.get_service().open(impl_.get_implementation(), protocol, ec);
     boost::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
    * boost::asio::ip::tcp::socket socket(my_context);
    * boost::system::error_code ec;
    * socket.open(boost::asio::ip::tcp::v4(), ec);
    * if (ec)
    * {
    *   // An error occurred.
    * }
    * @endcode
    */
   BOOST_ASIO_SYNC_OP_VOID open(const protocol_type& protocol,
       boost::system::error_code& ec)
   {
     impl_.get_service().open(impl_.get_implementation(), protocol, ec);
     BOOST_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 boost::system::system_error Thrown on failure.
    */
   void assign(const protocol_type& protocol,
       const native_handle_type& native_socket)
   {
     boost::system::error_code ec;
     impl_.get_service().assign(impl_.get_implementation(),
         protocol, native_socket, ec);
     boost::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.
    */
   BOOST_ASIO_SYNC_OP_VOID assign(const protocol_type& protocol,
       const native_handle_type& native_socket, boost::system::error_code& ec)
   {
     impl_.get_service().assign(impl_.get_implementation(),
         protocol, native_socket, ec);
     BOOST_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 boost::asio::error::operation_aborted error.
    *
    * @throws boost::system::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()
   {
     boost::system::error_code ec;
     impl_.get_service().close(impl_.get_implementation(), ec);
     boost::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 boost::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
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::system::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.
    */
   BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
   {
     impl_.get_service().close(impl_.get_implementation(), ec);
     BOOST_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 boost::asio::error::operation_aborted error. Ownership
    * of the native socket is then transferred to the caller.
    *
    * @throws boost::system::system_error Thrown on failure.
    *
    * @note This function is unsupported on Windows versions prior to Windows
    * 8.1, and will fail with boost::asio::error::operation_not_supported on
    * these platforms.
    */
 #if defined(BOOST_ASIO_MSVC) && (BOOST_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()
   {
     boost::system::error_code ec;
     native_handle_type s = impl_.get_service().release(
         impl_.get_implementation(), ec);
     boost::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 boost::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 boost::asio::error::operation_not_supported on
    * these platforms.
    */
 #if defined(BOOST_ASIO_MSVC) && (BOOST_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(boost::system::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 boost::asio::error::operation_aborted error.
    *
    * @throws boost::system::system_error Thrown on failure.
    *
    * @note Calls to cancel() will always fail with
    * boost::asio::error::operation_not_supported when run on Windows XP, Windows
    * Server 2003, and earlier versions of Windows, unless
    * BOOST_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
    * BOOST_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(BOOST_ASIO_MSVC) && (BOOST_ASIO_MSVC >= 1400) \
   && (!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0600) \
   && !defined(BOOST_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()
   {
     boost::system::error_code ec;
     impl_.get_service().cancel(impl_.get_implementation(), ec);
     boost::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 boost::asio::error::operation_aborted error.
    *
    * @param ec Set to indicate what error occurred, if any.
    *
    * @note Calls to cancel() will always fail with
    * boost::asio::error::operation_not_supported when run on Windows XP, Windows
    * Server 2003, and earlier versions of Windows, unless
    * BOOST_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
    * BOOST_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(BOOST_ASIO_MSVC) && (BOOST_ASIO_MSVC >= 1400) \
   && (!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0600) \
   && !defined(BOOST_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
   BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
   {
     impl_.get_service().cancel(impl_.get_implementation(), ec);
     BOOST_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 boost::system::system_error Thrown on failure.
    */
   bool at_mark() const
   {
     boost::system::error_code ec;
     bool b = impl_.get_service().at_mark(impl_.get_implementation(), ec);
     boost::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(boost::system::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 boost::system::system_error Thrown on failure.
    */
   std::size_t available() const
   {
     boost::system::error_code ec;
     std::size_t s = impl_.get_service().available(
         impl_.get_implementation(), ec);
     boost::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(boost::system::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 boost::system::system_error Thrown on failure.
    *
    * @par Example
    * @code
    * boost::asio::ip::tcp::socket socket(my_context);
    * socket.open(boost::asio::ip::tcp::v4());
    * socket.bind(boost::asio::ip::tcp::endpoint(
    *       boost::asio::ip::tcp::v4(), 12345));
    * @endcode
    */
   void bind(const endpoint_type& endpoint)
   {
     boost::system::error_code ec;
     impl_.get_service().bind(impl_.get_implementation(), endpoint, ec);
     boost::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
    * boost::asio::ip::tcp::socket socket(my_context);
    * socket.open(boost::asio::ip::tcp::v4());
    * boost::system::error_code ec;
    * socket.bind(boost::asio::ip::tcp::endpoint(
    *       boost::asio::ip::tcp::v4(), 12345), ec);
    * if (ec)
    * {
    *   // An error occurred.
    * }
    * @endcode
    */
   BOOST_ASIO_SYNC_OP_VOID bind(const endpoint_type& endpoint,
       boost::system::error_code& ec)
   {
     impl_.get_service().bind(impl_.get_implementation(), endpoint, ec);
     BOOST_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 boost::system::system_error Thrown on failure.
    *
    * @par Example
    * @code
    * boost::asio::ip::tcp::socket socket(my_context);
    * boost::asio::ip::tcp::endpoint endpoint(
    *     boost::asio::ip::address::from_string("1.2.3.4"), 12345);
    * socket.connect(endpoint);
    * @endcode
    */
   void connect(const endpoint_type& peer_endpoint)
   {
     boost::system::error_code ec;
     if (!is_open())
     {
       impl_.get_service().open(impl_.get_implementation(),
           peer_endpoint.protocol(), ec);
       boost::asio::detail::throw_error(ec, "connect");
     }
     impl_.get_service().connect(impl_.get_implementation(), peer_endpoint, ec);
     boost::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
    * boost::asio::ip::tcp::socket socket(my_context);
    * boost::asio::ip::tcp::endpoint endpoint(
    *     boost::asio::ip::address::from_string("1.2.3.4"), 12345);
    * boost::system::error_code ec;
    * socket.connect(endpoint, ec);
    * if (ec)
    * {
    *   // An error occurred.
    * }
    * @endcode
    */
   BOOST_ASIO_SYNC_OP_VOID connect(const endpoint_type& peer_endpoint,
       boost::system::error_code& ec)
   {
     if (!is_open())
     {
       impl_.get_service().open(impl_.get_implementation(),
             peer_endpoint.protocol(), ec);
       if (ec)
       {
         BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
       }
     }
 
     impl_.get_service().connect(impl_.get_implementation(), peer_endpoint, ec);
     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Start an asynchronous connect.
   /**
    * This function is used to asynchronously connect a socket to the specified
    * remote endpoint. It is an initiating function for an @ref
    * asynchronous_operation, and 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 token The @ref completion_token that will be used to produce a
    * completion handler, which will be called when the connect completes.
    * Potential completion tokens include @ref use_future, @ref use_awaitable,
    * @ref yield_context, or a function object with the correct completion
    * signature. The function signature of the completion handler must be:
    * @code void handler(
    *   const boost::system::error_code& error // Result of operation.
    * ); @endcode
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the completion 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 boost::asio::post().
    *
    * @par Completion Signature
    * @code void(boost::system::error_code) @endcode
    *
    * @par Example
    * @code
    * void connect_handler(const boost::system::error_code& error)
    * {
    *   if (!error)
    *   {
    *     // Connect succeeded.
    *   }
    * }
    *
    * ...
    *
    * boost::asio::ip::tcp::socket socket(my_context);
    * boost::asio::ip::tcp::endpoint endpoint(
    *     boost::asio::ip::address::from_string("1.2.3.4"), 12345);
    * socket.async_connect(endpoint, connect_handler);
    * @endcode
    *
    * @par Per-Operation Cancellation
    * On POSIX or Windows operating systems, this asynchronous operation supports
    * cancellation for the following boost::asio::cancellation_type values:
    *
    * @li @c cancellation_type::terminal
    *
    * @li @c cancellation_type::partial
    *
    * @li @c cancellation_type::total
    */
   template <
       BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code))
         ConnectToken = default_completion_token_t<executor_type>>
   auto async_connect(const endpoint_type& peer_endpoint,
       ConnectToken&& token = default_completion_token_t<executor_type>())
     -> decltype(
       async_initiate<ConnectToken, void (boost::system::error_code)>(
         declval<initiate_async_connect>(), token,
         peer_endpoint, declval<boost::system::error_code&>()))
   {
     boost::system::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<ConnectToken, void (boost::system::error_code)>(
         initiate_async_connect(this), token, 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 boost::system::system_error Thrown on failure.
    *
    * @sa SettableSocketOption @n
    * boost::asio::socket_base::broadcast @n
    * boost::asio::socket_base::do_not_route @n
    * boost::asio::socket_base::keep_alive @n
    * boost::asio::socket_base::linger @n
    * boost::asio::socket_base::receive_buffer_size @n
    * boost::asio::socket_base::receive_low_watermark @n
    * boost::asio::socket_base::reuse_address @n
    * boost::asio::socket_base::send_buffer_size @n
    * boost::asio::socket_base::send_low_watermark @n
    * boost::asio::ip::multicast::join_group @n
    * boost::asio::ip::multicast::leave_group @n
    * boost::asio::ip::multicast::enable_loopback @n
    * boost::asio::ip::multicast::outbound_interface @n
    * boost::asio::ip::multicast::hops @n
    * boost::asio::ip::tcp::no_delay
    *
    * @par Example
    * Setting the IPPROTO_TCP/TCP_NODELAY option:
    * @code
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::asio::ip::tcp::no_delay option(true);
    * socket.set_option(option);
    * @endcode
    */
   template <typename SettableSocketOption>
   void set_option(const SettableSocketOption& option)
   {
     boost::system::error_code ec;
     impl_.get_service().set_option(impl_.get_implementation(), option, ec);
     boost::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
    * boost::asio::socket_base::broadcast @n
    * boost::asio::socket_base::do_not_route @n
    * boost::asio::socket_base::keep_alive @n
    * boost::asio::socket_base::linger @n
    * boost::asio::socket_base::receive_buffer_size @n
    * boost::asio::socket_base::receive_low_watermark @n
    * boost::asio::socket_base::reuse_address @n
    * boost::asio::socket_base::send_buffer_size @n
    * boost::asio::socket_base::send_low_watermark @n
    * boost::asio::ip::multicast::join_group @n
    * boost::asio::ip::multicast::leave_group @n
    * boost::asio::ip::multicast::enable_loopback @n
    * boost::asio::ip::multicast::outbound_interface @n
    * boost::asio::ip::multicast::hops @n
    * boost::asio::ip::tcp::no_delay
    *
    * @par Example
    * Setting the IPPROTO_TCP/TCP_NODELAY option:
    * @code
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::asio::ip::tcp::no_delay option(true);
    * boost::system::error_code ec;
    * socket.set_option(option, ec);
    * if (ec)
    * {
    *   // An error occurred.
    * }
    * @endcode
    */
   template <typename SettableSocketOption>
   BOOST_ASIO_SYNC_OP_VOID set_option(const SettableSocketOption& option,
       boost::system::error_code& ec)
   {
     impl_.get_service().set_option(impl_.get_implementation(), option, ec);
     BOOST_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 boost::system::system_error Thrown on failure.
    *
    * @sa GettableSocketOption @n
    * boost::asio::socket_base::broadcast @n
    * boost::asio::socket_base::do_not_route @n
    * boost::asio::socket_base::keep_alive @n
    * boost::asio::socket_base::linger @n
    * boost::asio::socket_base::receive_buffer_size @n
    * boost::asio::socket_base::receive_low_watermark @n
    * boost::asio::socket_base::reuse_address @n
    * boost::asio::socket_base::send_buffer_size @n
    * boost::asio::socket_base::send_low_watermark @n
    * boost::asio::ip::multicast::join_group @n
    * boost::asio::ip::multicast::leave_group @n
    * boost::asio::ip::multicast::enable_loopback @n
    * boost::asio::ip::multicast::outbound_interface @n
    * boost::asio::ip::multicast::hops @n
    * boost::asio::ip::tcp::no_delay
    *
    * @par Example
    * Getting the value of the SOL_SOCKET/SO_KEEPALIVE option:
    * @code
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::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
   {
     boost::system::error_code ec;
     impl_.get_service().get_option(impl_.get_implementation(), option, ec);
     boost::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
    * boost::asio::socket_base::broadcast @n
    * boost::asio::socket_base::do_not_route @n
    * boost::asio::socket_base::keep_alive @n
    * boost::asio::socket_base::linger @n
    * boost::asio::socket_base::receive_buffer_size @n
    * boost::asio::socket_base::receive_low_watermark @n
    * boost::asio::socket_base::reuse_address @n
    * boost::asio::socket_base::send_buffer_size @n
    * boost::asio::socket_base::send_low_watermark @n
    * boost::asio::ip::multicast::join_group @n
    * boost::asio::ip::multicast::leave_group @n
    * boost::asio::ip::multicast::enable_loopback @n
    * boost::asio::ip::multicast::outbound_interface @n
    * boost::asio::ip::multicast::hops @n
    * boost::asio::ip::tcp::no_delay
    *
    * @par Example
    * Getting the value of the SOL_SOCKET/SO_KEEPALIVE option:
    * @code
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::asio::ip::tcp::socket::keep_alive option;
    * boost::system::error_code ec;
    * socket.get_option(option, ec);
    * if (ec)
    * {
    *   // An error occurred.
    * }
    * bool is_set = option.value();
    * @endcode
    */
   template <typename GettableSocketOption>
   BOOST_ASIO_SYNC_OP_VOID get_option(GettableSocketOption& option,
       boost::system::error_code& ec) const
   {
     impl_.get_service().get_option(impl_.get_implementation(), option, ec);
     BOOST_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 boost::system::system_error Thrown on failure.
    *
    * @sa IoControlCommand @n
    * boost::asio::socket_base::bytes_readable @n
    * boost::asio::socket_base::non_blocking_io
    *
    * @par Example
    * Getting the number of bytes ready to read:
    * @code
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::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)
   {
     boost::system::error_code ec;
     impl_.get_service().io_control(impl_.get_implementation(), command, ec);
     boost::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
    * boost::asio::socket_base::bytes_readable @n
    * boost::asio::socket_base::non_blocking_io
    *
    * @par Example
    * Getting the number of bytes ready to read:
    * @code
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::asio::ip::tcp::socket::bytes_readable command;
    * boost::system::error_code ec;
    * socket.io_control(command, ec);
    * if (ec)
    * {
    *   // An error occurred.
    * }
    * std::size_t bytes_readable = command.get();
    * @endcode
    */
   template <typename IoControlCommand>
   BOOST_ASIO_SYNC_OP_VOID io_control(IoControlCommand& command,
       boost::system::error_code& ec)
   {
     impl_.get_service().io_control(impl_.get_implementation(), command, ec);
     BOOST_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
    * boost::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
    * boost::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
    * boost::asio::error::would_block if they are unable to perform the requested
    * operation immediately. If @c false, synchronous operations will block
    * until complete.
    *
    * @throws boost::system::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
    * boost::asio::error::would_block.
    */
   void non_blocking(bool mode)
   {
     boost::system::error_code ec;
     impl_.get_service().non_blocking(impl_.get_implementation(), mode, ec);
     boost::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
    * boost::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
    * boost::asio::error::would_block.
    */
   BOOST_ASIO_SYNC_OP_VOID non_blocking(
       bool mode, boost::system::error_code& ec)
   {
     impl_.get_service().non_blocking(impl_.get_implementation(), mode, ec);
     BOOST_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 boost::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()(boost::system::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 = boost::system::error_code(n < 0 ? errno : 0,
    *             boost::asio::error::get_system_category());
    *         total_bytes_transferred_ += ec ? 0 : n;
    *
    *         // Retry operation immediately if interrupted by signal.
    *         if (ec == boost::asio::error::interrupted)
    *           continue;
    *
    *         // Check if we need to run the operation again.
    *         if (ec == boost::asio::error::would_block
    *             || ec == boost::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 boost::asio::error::would_block
    * (or the equivalent system error).
    *
    * @throws boost::system::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 boost::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()(boost::system::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 = boost::system::error_code(n < 0 ? errno : 0,
    *             boost::asio::error::get_system_category());
    *         total_bytes_transferred_ += ec ? 0 : n;
    *
    *         // Retry operation immediately if interrupted by signal.
    *         if (ec == boost::asio::error::interrupted)
    *           continue;
    *
    *         // Check if we need to run the operation again.
    *         if (ec == boost::asio::error::would_block
    *             || ec == boost::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)
   {
     boost::system::error_code ec;
     impl_.get_service().native_non_blocking(
         impl_.get_implementation(), mode, ec);
     boost::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 boost::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 boost::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()(boost::system::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 = boost::system::error_code(n < 0 ? errno : 0,
    *             boost::asio::error::get_system_category());
    *         total_bytes_transferred_ += ec ? 0 : n;
    *
    *         // Retry operation immediately if interrupted by signal.
    *         if (ec == boost::asio::error::interrupted)
    *           continue;
    *
    *         // Check if we need to run the operation again.
    *         if (ec == boost::asio::error::would_block
    *             || ec == boost::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
    */
   BOOST_ASIO_SYNC_OP_VOID native_non_blocking(
       bool mode, boost::system::error_code& ec)
   {
     impl_.get_service().native_non_blocking(
         impl_.get_implementation(), mode, ec);
     BOOST_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 boost::system::system_error Thrown on failure.
    *
    * @par Example
    * @code
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::asio::ip::tcp::endpoint endpoint = socket.local_endpoint();
    * @endcode
    */
   endpoint_type local_endpoint() const
   {
     boost::system::error_code ec;
     endpoint_type ep = impl_.get_service().local_endpoint(
         impl_.get_implementation(), ec);
     boost::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
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::system::error_code ec;
    * boost::asio::ip::tcp::endpoint endpoint = socket.local_endpoint(ec);
    * if (ec)
    * {
    *   // An error occurred.
    * }
    * @endcode
    */
   endpoint_type local_endpoint(boost::system::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 boost::system::system_error Thrown on failure.
    *
    * @par Example
    * @code
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::asio::ip::tcp::endpoint endpoint = socket.remote_endpoint();
    * @endcode
    */
   endpoint_type remote_endpoint() const
   {
     boost::system::error_code ec;
     endpoint_type ep = impl_.get_service().remote_endpoint(
         impl_.get_implementation(), ec);
     boost::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
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::system::error_code ec;
    * boost::asio::ip::tcp::endpoint endpoint = socket.remote_endpoint(ec);
    * if (ec)
    * {
    *   // An error occurred.
    * }
    * @endcode
    */
   endpoint_type remote_endpoint(boost::system::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 boost::system::system_error Thrown on failure.
    *
    * @par Example
    * Shutting down the send side of the socket:
    * @code
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * socket.shutdown(boost::asio::ip::tcp::socket::shutdown_send);
    * @endcode
    */
   void shutdown(shutdown_type what)
   {
     boost::system::error_code ec;
     impl_.get_service().shutdown(impl_.get_implementation(), what, ec);
     boost::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
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::system::error_code ec;
    * socket.shutdown(boost::asio::ip::tcp::socket::shutdown_send, ec);
    * if (ec)
    * {
    *   // An error occurred.
    * }
    * @endcode
    */
   BOOST_ASIO_SYNC_OP_VOID shutdown(shutdown_type what,
       boost::system::error_code& ec)
   {
     impl_.get_service().shutdown(impl_.get_implementation(), what, ec);
     BOOST_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
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * socket.wait(boost::asio::ip::tcp::socket::wait_read);
    * @endcode
    */
   void wait(wait_type w)
   {
     boost::system::error_code ec;
     impl_.get_service().wait(impl_.get_implementation(), w, ec);
     boost::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
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * boost::system::error_code ec;
    * socket.wait(boost::asio::ip::tcp::socket::wait_read, ec);
    * @endcode
    */
   BOOST_ASIO_SYNC_OP_VOID wait(wait_type w, boost::system::error_code& ec)
   {
     impl_.get_service().wait(impl_.get_implementation(), w, ec);
     BOOST_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. It is an initiating
    * function for an @ref asynchronous_operation, and always returns
    * immediately.
    *
    * @param w Specifies the desired socket state.
    *
    * @param token The @ref completion_token that will be used to produce a
    * completion handler, which will be called when the wait completes. Potential
    * completion tokens include @ref use_future, @ref use_awaitable, @ref
    * yield_context, or a function object with the correct completion signature.
    * The function signature of the completion handler must be:
    * @code void handler(
    *   const boost::system::error_code& error // Result of operation.
    * ); @endcode
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the completion 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 boost::asio::post().
    *
    * @par Completion Signature
    * @code void(boost::system::error_code) @endcode
    *
    * @par Example
    * @code
    * void wait_handler(const boost::system::error_code& error)
    * {
    *   if (!error)
    *   {
    *     // Wait succeeded.
    *   }
    * }
    *
    * ...
    *
    * boost::asio::ip::tcp::socket socket(my_context);
    * ...
    * socket.async_wait(boost::asio::ip::tcp::socket::wait_read, wait_handler);
    * @endcode
    *
    * @par Per-Operation Cancellation
    * On POSIX or Windows operating systems, this asynchronous operation supports
    * cancellation for the following boost::asio::cancellation_type values:
    *
    * @li @c cancellation_type::terminal
    *
    * @li @c cancellation_type::partial
    *
    * @li @c cancellation_type::total
    */
   template <
       BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code))
         WaitToken = default_completion_token_t<executor_type>>
   auto async_wait(wait_type w,
       WaitToken&& token = default_completion_token_t<executor_type>())
     -> decltype(
       async_initiate<WaitToken, void (boost::system::error_code)>(
           declval<initiate_async_wait>(), token, w))
   {
     return async_initiate<WaitToken, void (boost::system::error_code)>(
         initiate_async_wait(this), token, 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(BOOST_ASIO_WINDOWS_RUNTIME)
   detail::io_object_impl<
     detail::null_socket_service<Protocol>, Executor> impl_;
 #elif defined(BOOST_ASIO_HAS_IOCP)
   detail::io_object_impl<
     detail::win_iocp_socket_service<Protocol>, Executor> impl_;
 #elif defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
   detail::io_object_impl<
     detail::io_uring_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&) = delete;
   basic_socket& operator=(const basic_socket&) = delete;
 
   class initiate_async_connect
   {
   public:
     typedef Executor executor_type;
 
     explicit initiate_async_connect(basic_socket* self)
       : self_(self)
     {
     }
 
     const executor_type& get_executor() const noexcept
     {
       return self_->get_executor();
     }
 
     template <typename ConnectHandler>
     void operator()(ConnectHandler&& handler,
         const endpoint_type& peer_endpoint,
         const boost::system::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.
       BOOST_ASIO_CONNECT_HANDLER_CHECK(ConnectHandler, handler) type_check;
 
       if (open_ec)
       {
           boost::asio::post(self_->impl_.get_executor(),
               boost::asio::detail::bind_handler(
                 static_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_executor());
       }
     }
 
   private:
     basic_socket* self_;
   };
 
   class initiate_async_wait
   {
   public:
     typedef Executor executor_type;
 
     explicit initiate_async_wait(basic_socket* self)
       : self_(self)
     {
     }
 
     const executor_type& get_executor() const noexcept
     {
       return self_->get_executor();
     }
 
     template <typename WaitHandler>
     void operator()(WaitHandler&& handler, 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.
       BOOST_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_executor());
     }
 
   private:
     basic_socket* self_;
   };
 };
 
 } // namespace asio
 } // namespace boost
 
 #include <boost/asio/detail/pop_options.hpp>
 
 #endif // BOOST_ASIO_BASIC_SOCKET_HPP

This page was automatically generated by the 2.3.7 LXR engine. The LXR team