CAsyncSocket Class

Article
04/28/2015

Represents a Windows Socket — an endpoint of network communication.

class CAsyncSocket : public CObject

Members

Public Constructors

Name	Description
CAsyncSocket::CAsyncSocket	Constructs a CAsyncSocket object.

Public Methods

Name	Description
CAsyncSocket::Accept	Accepts a connection on the socket.
CAsyncSocket::AsyncSelect	Requests event notification for the socket.
CAsyncSocket::Attach	Attaches a socket handle to a CAsyncSocket object.
CAsyncSocket::Bind	Associates a local address with the socket.
CAsyncSocket::Close	Closes the socket.
CAsyncSocket::Connect	Establishes a connection to a peer socket.
CAsyncSocket::Create	Creates a socket.
CAsyncSocket::Detach	Detaches a socket handle from a CAsyncSocket object.
CAsyncSocket::FromHandle	Returns a pointer to a CAsyncSocket object, given a socket handle.
CAsyncSocket::GetLastError	Gets the error status for the last operation that failed.
CAsyncSocket::GetPeerName	Gets the address of the peer socket to which the socket is connected.
CAsyncSocket::GetPeerNameEx	Gets the address of the peer socket to which the socket is connected (handles IPv6 addresses).
CAsyncSocket::GetSockName	Gets the local name for a socket.
CAsyncSocket::GetSockNameEx	Gets the local name for a socket (handles IPv6 addresses).
CAsyncSocket::GetSockOpt	Retrieves a socket option.
CAsyncSocket::IOCtl	Controls the mode of the socket.
CAsyncSocket::Listen	Establishes a socket to listen for incoming connection requests.
CAsyncSocket::Receive	Receives data from the socket.
CAsyncSocket::ReceiveFrom	Receives a datagram and stores the source address.
CAsyncSocket::ReceiveFromEx	Receives a datagram and stores the source address (handles IPv6 addresses).
CAsyncSocket::Send	Sends data to a connected socket.
CAsyncSocket::SendTo	Sends data to a specific destination.
CAsyncSocket::SendToEx	Sends data to a specific destination (handles IPv6 addresses).
CAsyncSocket::SetSockOpt	Sets a socket option.
CAsyncSocket::ShutDown	Disables Send and/or Receive calls on the socket.
CASyncSocket::Socket	Allocates a socket handle.

Protected Methods

Name	Description
CAsyncSocket::OnAccept	Notifies a listening socket that it can accept pending connection requests by calling Accept.
CAsyncSocket::OnClose	Notifies a socket that the socket connected to it has closed.
CAsyncSocket::OnConnect	Notifies a connecting socket that the connection attempt is complete, whether successfully or in error.
CAsyncSocket::OnOutOfBandData	Notifies a receiving socket that there is out-of-band data to be read on the socket, usually an urgent message.
CAsyncSocket::OnReceive	Notifies a listening socket that there is data to be retrieved by calling Receive.
CAsyncSocket::OnSend	Notifies a socket that it can send data by calling Send.

Public Operators

Name	Description
CAsyncSocket::operator =	Assigns a new value to a CAsyncSocket object.
CAsyncSocket::operator SOCKET	Use this operator to retrieve the SOCKET handle of the CAsyncSocket object.

Public Data Members

Name	Description
CAsyncSocket::m_hSocket	Indicates the SOCKET handle attached to this CAsyncSocket object.

Remarks

Class CAsyncSocket encapsulates the Windows Socket Functions API, providing an object-oriented abstraction for programmers who want to use Windows Sockets in conjunction with MFC.

This class is based on the assumption that you understand network communications. You are responsible for handling blocking, byte-order differences, and conversions between Unicode and multibyte character set (MBCS) strings. If you want a more convenient interface that manages these issues for you, see class CSocket.

To use a CAsyncSocket object, call its constructor, then call the Create function to create the underlying socket handle (type SOCKET), except on accepted sockets. For a server socket call the Listen member function, and for a client socket call the Connect member function. The server socket should call the Accept function upon receiving a connection request. Use the remaining CAsyncSocket functions to carry out communications between sockets. Upon completion, destroy the CAsyncSocket object if it was created on the heap; the destructor automatically calls the Close function. The SOCKET data type is described in the article Windows Sockets: Background.

Note

When using MFC sockets in secondary threads in a statically linked MFC application, you must call AfxSocketInit in each thread that uses sockets to initialize the socket libraries. By default, AfxSocketInit is called only in the primary thread.

For more information, see Windows Sockets: Using Class CAsyncSocket and related articles., as well as Windows Sockets 2 API.

Inheritance Hierarchy

CObject

CAsyncSocket

Requirements

Header: afxsock.h