Windsock套接字I/O模型学习 --- 第三章

1. WSAAsyncSelect 模型

WSAAsyncSelect 模型比较简单，是为了适应Windows的消息驱动环境而设置的,WSAAsyncSelect 函数自动把套接字设为非阻塞模式。MFC（ Microsoft Foundation Class， Microsoft 基础类库）中的CSocket 类也使用了它

2. 应用举例

// WSAAyncSelectDemo.cpp : Defines the entry point for the application.
//

#include "stdafx.h"
#include "WSAAyncSelectDemo.h"
#include <WinSock2.h>
#include <cstdlib>

#define MAX_LOADSTRING 100
#define WM_SOCKET (WM_USER + 100)

// Global Variables:
HINSTANCE hInst;                                // current instance
WCHAR szTitle[MAX_LOADSTRING];                  // The title bar text
WCHAR szWindowClass[MAX_LOADSTRING];            // the main window class name

// Forward declarations of functions included in this code module:
ATOM                MyRegisterClass(HINSTANCE hInstance);
BOOL                InitInstance(HINSTANCE, int);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK    About(HWND, UINT, WPARAM, LPARAM);

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
                     _In_opt_ HINSTANCE hPrevInstance,
                     _In_ LPWSTR    lpCmdLine,
                     _In_ int       nCmdShow)
{
    UNREFERENCED_PARAMETER(hPrevInstance);
    UNREFERENCED_PARAMETER(lpCmdLine);

    // TODO: Place code here.

    // Initialize global strings
    LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
    LoadStringW(hInstance, IDC_WSAAYNCSELECT, szWindowClass, MAX_LOADSTRING);
    MyRegisterClass(hInstance);

    // Perform application initialization:
    if (!InitInstance (hInstance, nCmdShow))
    {
        return FALSE;
    }

    HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_WSAAYNCSELECT));

    MSG msg;

    // Main message loop:
    while (GetMessage(&msg, nullptr, 0, 0))
    {
        if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }

    return (int) msg.wParam;
}



//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEXW wcex;

    wcex.cbSize = sizeof(WNDCLASSEX);

    wcex.style          = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = WndProc;
    wcex.cbClsExtra     = 0;
    wcex.cbWndExtra     = 0;
    wcex.hInstance      = hInstance;
    wcex.hIcon          = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_WSAAYNCSELECT));
    wcex.hCursor        = LoadCursor(nullptr, IDC_ARROW);
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName   = MAKEINTRESOURCEW(IDC_WSAAYNCSELECT);
    wcex.lpszClassName  = szWindowClass;
    wcex.hIconSm        = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

    return RegisterClassExW(&wcex);
}

//
//   FUNCTION: InitInstance(HINSTANCE, int)
//
//   PURPOSE: Saves instance handle and creates main window
//
//   COMMENTS:
//
//        In this function, we save the instance handle in a global variable and
//        create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   hInst = hInstance; // Store instance handle in our global variable

   HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);

   if (!hWnd)
   {
      return FALSE;
   }

   USHORT nPort = 4567;  // 此服务器监听的端口号
   SOCKET sListen = ::socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
   sockaddr_in sin;
   sin.sin_family = AF_INET;
   sin.sin_port = htons(nPort);
   sin.sin_addr.S_un.S_addr = INADDR_ANY;

   if (::bind(sListen, (sockaddr *)&sin, sizeof(sin)) == SOCKET_ERROR)
   {
	   return FALSE;
   }

   ::WSAAsyncSelect(sListen, hWnd, WM_SOCKET, FD_ACCEPT | FD_CLOSE);
   ::listen(sListen, 5); // 进入监听模式

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}

//
//  FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  PURPOSE:  Processes messages for the main window.
//
//  WM_COMMAND  - process the application menu
//  WM_PAINT    - Paint the main window
//  WM_DESTROY  - post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	switch (message)
	{
	case WM_SOCKET:
	{ 
		SOCKET s = wParam; // 取得有事件发生的套接字句柄
						 // 查看是否出错
		if (WSAGETSELECTERROR(lParam))
		{
			::closesocket(s);
			return 0;
		}
		// 处理发生的事件
		switch (WSAGETSELECTEVENT(lParam))
		{
		case FD_ACCEPT: // 监听中的套接字检测到有连接进入
		{
			SOCKET client = ::accept(s, NULL, NULL);
			::WSAAsyncSelect(client,
				hWnd, WM_SOCKET, FD_READ | FD_WRITE | FD_CLOSE);
		}
		break;
		case FD_WRITE:
		{ }
		break;
		case FD_READ:
		{ 
			char szText[1024] = { 0 };
			if (::recv(s, szText, 1024, 0) == -1) 
				::closesocket(s);
			else
			{
				TCHAR szOut[256] = { 0 };
				std::mbtowc(szOut, szText, strlen(szText));
				OutputDebugString(szOut);
			}
		}
		break;
		case FD_CLOSE:
		{ 
			::closesocket(s); }
		break;
		}
	}
	break;
    case WM_COMMAND:
        {
            int wmId = LOWORD(wParam);
            // Parse the menu selections:
            switch (wmId)
            {
            case IDM_ABOUT:
                DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
                break;
            case IDM_EXIT:
                DestroyWindow(hWnd);
                break;
            default:
                return DefWindowProc(hWnd, message, wParam, lParam);
            }
        }
        break;
    case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hWnd, &ps);
            // TODO: Add any drawing code that uses hdc here...
            EndPaint(hWnd, &ps);
        }
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

// Message handler for about box.
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
    UNREFERENCED_PARAMETER(lParam);
    switch (message)
    {
    case WM_INITDIALOG:
        return (INT_PTR)TRUE;

    case WM_COMMAND:
        if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
        {
            EndDialog(hDlg, LOWORD(wParam));
            return (INT_PTR)TRUE;
        }
        break;
    }
    return (INT_PTR)FALSE;
}

注：目前win32程序中WSAAsyncSelect已经是弃用的api，一般会推荐使用WSAEventSelect,这个是接下来要说的一个I/O模型