Socket I/O模型之异步选择(WSAAsyncSelect)

使用异步选择模型，应用程序可在一个套接字上，接收以Windows消息为基础的网络事件通知。具体的做法是在建好一个套接字后，调用WSAAsyncSelect函数。

服务器端代码：

C++代码  

1. // write by larry  
2. // 2009-8-20  
3. // This is a server using WSAAsyncSelect model.  
4. #include "stdafx.h"  
5. #include <winsock.h>  
6. #include <tchar.h>  
7. #define PORT  5150  
8. #define MSGSIZE  1024  
9. #define WM_SOCKET  WM_USER+0  
10. #pragma comment(lib, "ws2_32.lib")  
11. LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);  
12. int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)  
13. {  
14.     static TCHAR szAppName[] = _T("AsyncSelect Model");  
15.     HWND hwnd;  
16.     MSG msg;  
17.     WNDCLASS wndclass;  
18.     wndclass.style         = CS_HREDRAW | CS_VREDRAW;  
19.     wndclass.lpfnWndProc   = WndProc;  
20.     wndclass.cbClsExtra    = 0;  
21.     wndclass.cbWndExtra    = 0;  
22.     wndclass.hInstance     = hInstance;  
23.     wndclass.hIcon         = LoadIcon(NULL, IDI_APPLICATION);  
24.     wndclass.hCursor       = LoadCursor(NULL, IDC_ARROW);  
25.     wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);  
26.     wndclass.lpszMenuName  = NULL;  
27.     wndclass.lpszClassName = szAppName;  
28.     if (!RegisterClass(&wndclass))  
29.     {  
30.         MessageBox(NULL, _T("This program requires Windows NT!"), szAppName, MB_ICONERROR);  
31.         return 0;  
32.     }  
33.     hwnd = CreateWindow(szAppName, // window class name  
34.         _T("AsyncSelect Model"),   // window caption  
35.         WS_OVERLAPPEDWINDOW,       // window stype  
36.         CW_USEDEFAULT,             // initial x postion  
37.         CW_USEDEFAULT,             // initial y postion  
38.         CW_USEDEFAULT,             // initial x size  
39.         CW_USEDEFAULT,             // initial y size  
40.         NULL,                      // parent window handle  
41.         NULL,                      // window menu handle  
42.         hInstance,                 // program instance handle  
43.         NULL);                     // creation parameters  
44.     ShowWindow(hwnd, nCmdShow);  
45.     UpdateWindow(hwnd);  
46.     while (GetMessage(&msg, NULL, 0, 0))  
47.     {  
48.         TranslateMessage(&msg);  
49.         DispatchMessage(&msg);  
50.     }  
51.     return msg.wParam;  
52. }  
53. LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)  
54. {  
55.     WSADATA wsaData;  
56.     static SOCKET sListen;  
57.     SOCKET sClient;  
58.     SOCKADDR_IN local, client;  
59.     int ret, iAddrSize = sizeof(client);  
60.     char szMessage[MSGSIZE];  
61.     switch (message)  
62.     {  
63.     case WM_CREATE:  
64.         // Initialize windows socket library  
65.         WSAStartup(0x0202, &wsaData);  
66.         // Create listening socket  
67.         sListen = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);  
68.         // Bind  
69.         local.sin_family = AF_INET;  
70.         local.sin_addr.S_un.S_addr = htonl(INADDR_ANY);  
71.         local.sin_port = htons(PORT);  
72.         bind(sListen, (sockaddr*)&local, sizeof(SOCKADDR_IN));  
73.         // Listen  
74.         listen(sListen, 3);  
75.         // Associate listening socket with FD_ACCEPT event  
76.         WSAAsyncSelect(sListen, hwnd, WM_SOCKET, FD_ACCEPT);  
77.         return 0;  
78.     case WM_DESTROY:  
79.         closesocket(sListen);  
80.         WSACleanup();  
81.         PostQuitMessage(0);  
82.         return 0;  
83.     case WM_SOCKET:  
84.         if (WSAGETSELECTERROR(lParam))  
85.         {  
86.             closesocket(wParam);  
87.             break;  
88.         }  
89.         switch (WSAGETSELECTEVENT(lParam))  
90.         {  
91.         case FD_ACCEPT:  
92.             // Accept a connection from client  
93.             sClient = accept(wParam, (sockaddr*)&client, &iAddrSize);  
94.             // Associate client socket with FD_READ and FD_CLOSE event  
95.             WSAAsyncSelect(sClient, hwnd, WM_SOCKET, FD_READ | FD_CLOSE);  
96.             break;  
97.         case FD_READ:  
98.             ret = recv(wParam, szMessage, MSGSIZE, 0);  
99.             if (ret == 0 || (ret == SOCKET_ERROR && WSAGetLastError() == WSAECONNRESET))  
100.             {  
101.                 closesocket(wParam);  
102.             }  
103.             else  
104.             {  
105.                 szMessage[ret] = '\0';  
106.                 send(wParam, szMessage, strlen(szMessage), 0);  
107.             }  
108.             break;  
109.         case FD_CLOSE:  
110.             closesocket(wParam);  
111.             break;  
112.         }  
113.         return 0;  
114.     }  
115.     return DefWindowProc(hwnd, message, wParam, lParam);  
116. }  

// write by larry// 2009-8-20// This is a server using WSAAsyncSelect model.#include "stdafx.h"#include <winsock.h>#include <tchar.h>#define PORT  5150#define MSGSIZE  1024#define WM_SOCKET  WM_USER+0#pragma comment(lib, "ws2_32.lib")LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow){ static TCHAR szAppName[] = _T("AsyncSelect Model");HWND hwnd;MSG msg;WNDCLASS wndclass;wndclass.style         = CS_HREDRAW | CS_VREDRAW;wndclass.lpfnWndProc   = WndProc;wndclass.cbClsExtra    = 0;wndclass.cbWndExtra    = 0;wndclass.hInstance     = hInstance;wndclass.hIcon         = LoadIcon(NULL, IDI_APPLICATION);wndclass.hCursor       = LoadCursor(NULL, IDC_ARROW);wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);wndclass.lpszMenuName  = NULL;wndclass.lpszClassName = szAppName;if (!RegisterClass(&wndclass)){MessageBox(NULL, _T("This program requires Windows NT!"), szAppName, MB_ICONERROR);return 0;}hwnd = CreateWindow(szAppName, // window class name_T("AsyncSelect Model"),   // window captionWS_OVERLAPPEDWINDOW,       // window stypeCW_USEDEFAULT,             // initial x postionCW_USEDEFAULT,             // initial y postionCW_USEDEFAULT,             // initial x sizeCW_USEDEFAULT,             // initial y sizeNULL,                      // parent window handleNULL,                      // window menu handlehInstance,                 // program instance handleNULL);                     // creation parametersShowWindow(hwnd, nCmdShow);UpdateWindow(hwnd);while (GetMessage(&msg, NULL, 0, 0)){TranslateMessage(&msg);DispatchMessage(&msg);}return msg.wParam;}LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam){WSADATA wsaData;static SOCKET sListen;SOCKET sClient;SOCKADDR_IN local, client;int ret, iAddrSize = sizeof(client);char szMessage[MSGSIZE];switch (message){case WM_CREATE:// Initialize windows socket libraryWSAStartup(0x0202, &wsaData);// Create listening socketsListen = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);// Bindlocal.sin_family = AF_INET;local.sin_addr.S_un.S_addr = htonl(INADDR_ANY);local.sin_port = htons(PORT);bind(sListen, (sockaddr*)&local, sizeof(SOCKADDR_IN));// Listenlisten(sListen, 3);// Associate listening socket with FD_ACCEPT eventWSAAsyncSelect(sListen, hwnd, WM_SOCKET, FD_ACCEPT);return 0;case WM_DESTROY:closesocket(sListen);WSACleanup();PostQuitMessage(0);return 0;case WM_SOCKET:if (WSAGETSELECTERROR(lParam)){closesocket(wParam);break;}switch (WSAGETSELECTEVENT(lParam)){case FD_ACCEPT:// Accept a connection from clientsClient = accept(wParam, (sockaddr*)&client, &iAddrSize);// Associate client socket with FD_READ and FD_CLOSE eventWSAAsyncSelect(sClient, hwnd, WM_SOCKET, FD_READ | FD_CLOSE);break;case FD_READ:ret = recv(wParam, szMessage, MSGSIZE, 0);if (ret == 0 || (ret == SOCKET_ERROR && WSAGetLastError() == WSAECONNRESET)){closesocket(wParam);}else{szMessage[ret] = '\0';send(wParam, szMessage, strlen(szMessage), 0);}break;case FD_CLOSE:closesocket(wParam);break;}return 0;}return DefWindowProc(hwnd, message, wParam, lParam);}

服务器端得主要流程：
1.在WM_CREATE消息处理函数中，初始化Windows Socket library，创建监听套接字，绑定，监听，并且调用WSAAsyncSelect函数表示我们关心在监听套接字上发生的FD_ACCEPT事件；
2.自定义一个消息WM_SOCKET，一旦在我们所关心的套接字（监听套接字和客户端套接字）上发生了某个事件，系统就会调用WndProc并且message参数被设置为WM_SOCKET；
3.在WM_SOCKET的消息处理函数中，分别对FD_ACCEPT、FD_READ和FD_CLOSE事件进行处理；
4.在窗口销毁消息(WM_DESTROY)的处理函数中，我们关闭监听套接字，清除Windows Socket library

WSAAsyncSelect函数的网络事件类型可以有以下一种：
FD_READ 应用程序想要接收有关是否可读的通知，以便读入数据
FD_WRITE 应用程序想要接收有关是否可写的通知，以便写入数据
FD_OOB 应用程序想接收是否有带外（OOB）数据抵达的通知
FD_ACCEPT 应用程序想接收与进入连接有关的通知
FD_CONNECT 应用程序想接收与一次连接或者多点join操作完成的通知
FD_CLOSE 应用程序想接收与套接字关闭有关的通知
FD_QOS 应用程序想接收套接字“服务质量”（QoS）发生更改的通知
FD_GROUP_QOS  应用程序想接收套接字组“服务质量”发生更改的通知（现在没什么用处，为未来套接字组的使用保留）
FD_ROUTING_INTERFACE_CHANGE 应用程序想接收在指定的方向上，与路由接口发生变化的通知
FD_ADDRESS_LIST_CHANGE  应用程序想接收针对套接字的协议家族，本地地址列表发生变化的通知