基于消息的异步套接字编程

╰+攻爆jí腚メ 2022-08-06 06:20 146阅读 0赞

// Chat2Dlg.cpp : 实现文件 // \#include "stdafx.h" \#include "Chat2.h" \#include "Chat2Dlg.h" \#ifdef \_DEBUG \#define new DEBUG\_NEW \#endif // 用于应用程序“关于”菜单项的 CAboutDlg 对话框 class CAboutDlg : public CDialog \{ public: CAboutDlg(); // 对话框数据 enum \{ IDD = IDD\_ABOUTBOX \}; protected: virtual void DoDataExchange(CDataExchange\* pDX); // DDX/DDV 支持 // 实现 protected: DECLARE\_MESSAGE\_MAP() \}; CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD) \{ \} void CAboutDlg::DoDataExchange(CDataExchange\* pDX) \{ CDialog::DoDataExchange(pDX); \} BEGIN\_MESSAGE\_MAP(CAboutDlg, CDialog) END\_MESSAGE\_MAP() // CChat2Dlg 对话框 CChat2Dlg::CChat2Dlg(CWnd\* pParent /\*=NULL\*/) : CDialog(CChat2Dlg::IDD, pParent) \{ m\_hIcon = AfxGetApp()->LoadIcon(IDR\_MAINFRAME); \} CChat2Dlg::~CChat2Dlg() \{ if (m\_sock) \{ closesocket(m\_sock); \} \} void CChat2Dlg::DoDataExchange(CDataExchange\* pDX) \{ CDialog::DoDataExchange(pDX); \} BEGIN\_MESSAGE\_MAP(CChat2Dlg, CDialog) ON\_WM\_SYSCOMMAND() ON\_WM\_PAINT() ON\_WM\_QUERYDRAGICON() ON\_MESSAGE(WM\_SOCK, OnSock) //\}\}AFX\_MSG\_MAP ON\_BN\_CLICKED(IDC\_BTN\_SEND, &CChat2Dlg::OnBnClickedBtnSend) END\_MESSAGE\_MAP() // CChat2Dlg 消息处理程序 BOOL CChat2Dlg::OnInitDialog() \{ CDialog::OnInitDialog(); // 将“关于...”菜单项添加到系统菜单中。 // IDM\_ABOUTBOX 必须在系统命令范围内。 ASSERT((IDM\_ABOUTBOX & 0xFFF0) == IDM\_ABOUTBOX); ASSERT(IDM\_ABOUTBOX < 0xF000); CMenu\* pSysMenu = GetSystemMenu(FALSE); if (pSysMenu != NULL) \{ CString strAboutMenu; strAboutMenu.LoadString(IDS\_ABOUTBOX); if (!strAboutMenu.IsEmpty()) \{ pSysMenu->AppendMenu(MF\_SEPARATOR); pSysMenu->AppendMenu(MF\_STRING, IDM\_ABOUTBOX, strAboutMenu); \} \} // 设置此对话框的图标。当应用程序主窗口不是对话框时，框架将自动 // 执行此操作 SetIcon(m\_hIcon, TRUE); // 设置大图标 SetIcon(m\_hIcon, FALSE); // 设置小图标 // TODO: 在此添加额外的初始化代码 InitSocket(); return TRUE; // 除非将焦点设置到控件，否则返回 TRUE \} void CChat2Dlg::OnSysCommand(UINT nID, LPARAM lParam) \{ if ((nID & 0xFFF0) == IDM\_ABOUTBOX) \{ CAboutDlg dlgAbout; dlgAbout.DoModal(); \} else \{ CDialog::OnSysCommand(nID, lParam); \} \} // 如果向对话框添加最小化按钮，则需要下面的代码 // 来绘制该图标。对于使用文档/视图模型的 MFC 应用程序， // 这将由框架自动完成。 void CChat2Dlg::OnPaint() \{ if (IsIconic()) \{ CPaintDC dc(this); // 用于绘制的设备上下文 SendMessage(WM\_ICONERASEBKGND, reinterpret\_cast<WPARAM>(dc.GetSafeHdc()), 0); // 使图标在工作区矩形中居中 int cxIcon = GetSystemMetrics(SM\_CXICON); int cyIcon = GetSystemMetrics(SM\_CYICON); CRect rect; GetClientRect(&rect); int x = (rect.Width() - cxIcon + 1) / 2; int y = (rect.Height() - cyIcon + 1) / 2; // 绘制图标 dc.DrawIcon(x, y, m\_hIcon); \} else \{ CDialog::OnPaint(); \} \} //当用户拖动最小化窗口时系统调用此函数取得光标 //显示。 HCURSOR CChat2Dlg::OnQueryDragIcon() \{ return static\_cast<HCURSOR>(m\_hIcon); \} BOOL CChat2Dlg::InitSocket(void) \{ m\_sock = WSASocket(AF\_INET, SOCK\_DGRAM, 0, NULL, 0, 0); if(INVALID\_SOCKET == m\_sock) \{ AfxMessageBox(\_T("Failed to create socket")); return FALSE; \} SOCKADDR\_IN addrSock; addrSock.sin\_addr.S\_un.S\_addr = htonl(INADDR\_ANY); addrSock.sin\_family = AF\_INET; addrSock.sin\_port = htons(6000); if(SOCKET\_ERROR == bind(m\_sock, (SOCKADDR\*)&addrSock, sizeof(SOCKADDR))) \{ AfxMessageBox(\_T("Failed to bind")); return FALSE; \} if(SOCKET\_ERROR == WSAAsyncSelect(m\_sock, m\_hWnd,WM\_SOCK, FD\_READ)) \{ AfxMessageBox(\_T("Failed to request windows msg\_based notification")/ \_T("of network event for the socket")); return FALSE; \} return TRUE; \} LRESULT CChat2Dlg::OnSock(WPARAM wParam, LPARAM lParam) \{ switch(LOWORD(lParam)) \{ case FD\_READ: CString str; CString strTemp; WSABUF wsabuf; wsabuf.buf = new char\[200\]; wsabuf.len = 200; DWORD dwRead; DWORD dwFlag = 0; SOCKADDR\_IN addrFrom; int len = sizeof(SOCKADDR); if(SOCKET\_ERROR == WSARecvFrom(m\_sock, &wsabuf, 1, &dwRead, &dwFlag, (SOCKADDR\*)&addrFrom, &len, NULL, NULL)) \{ AfxMessageBox(\_T("Failed to receive data")); return 0L; \} HOSTENT \*pHost; pHost = gethostbyaddr((char\*)&(addrFrom.sin\_addr.S\_un.S\_addr), 4, AF\_INET); str.Format(\_T("%s say %s"), pHost->h\_name, wsabuf.buf); str += \_T("/r/n"); GetDlgItemText(IDC\_EDIT\_RECV, strTemp); str += strTemp; SetDlgItemText(IDC\_EDIT\_RECV, str); break; \} return 0L; \} void CChat2Dlg::OnBnClickedBtnSend() \{ // TODO: 在此添加控件通知处理程序代码 DWORD dwIP; CString strHostName; HOSTENT\* pHost; SOCKADDR\_IN addrTo; if (GetDlgItemText(IDC\_EDIT\_HOST, strHostName), strHostName == \_T("")) \{ ((CIPAddressCtrl\*)GetDlgItem(IDC\_IPADDRESS1))->GetAddress(dwIP); addrTo.sin\_addr.S\_un.S\_addr = htonl(dwIP); \} else \{ pHost = gethostbyname(strHostName); addrTo.sin\_addr.S\_un.S\_addr = \*((DWORD\*)(pHost->h\_addr\_list\[0\])); \} addrTo.sin\_family = AF\_INET; addrTo.sin\_port = htons(6000); CString strSend; GetDlgItemText(IDC\_EDIT\_SEND, strSend); SetDlgItemText(IDC\_EDIT\_SEND, \_T("")); WSABUF wsabuf; DWORD dwSend; int len = strSend.GetLength(); wsabuf.buf = strSend.GetBuffer(len); wsabuf.len = len+1; if(SOCKET\_ERROR == WSASendTo(m\_sock, &wsabuf, 1, &dwSend, 0, (SOCKADDR\*)&addrTo, sizeof(SOCKADDR), NULL, NULL)) \{ AfxMessageBox(\_T("Failed to send data")); return; \} \}

n  Windows Sockets的异步选择函数WSAAsyncSelect()提供了消息机制的网络事件选择，当使用它登记的网络事件发生时，Windows应用程序相应的窗口函数将收到一个消息，消息中指示了发生的网络事件，以及与事件相关的一些信息。

Windows Sockets为了支持Windows消息驱动机制，使应用程序开发者能够方便地处理网络通信，它对网络事件采用了基于消息的异步存取策略。   Windows套接字在两种模式下执行I/O操作，阻塞和非阻塞。在阻塞模式下，在I/O操作完成前，执行操作的Winsock函数会一直等待下去，不会立即返回程序(将控制权交还给程序)。而在非阻塞模式下，Winsock函数无论如何都会立即返回。