套接字之重疊I/O模型

剛剛把重疊I/O套接字理解了一點，於是在此做個筆記，給出一個重疊I/O處理單個套接字的程序。

 

這個程序是TCP的服務器端程序。該程序只能接收一個客戶端的連接，循環發送信息，以及該客戶端退出時服務器端得到響應。

 

套接字庫初始化等代碼省略了，只包含一個監聽部分和一個處理I/O部分的代碼。如下：

 

void COVERLAPPEDDlg::OnButton1() //開啓服務器按鈕 { // TODO: Add your control notification handler code here WSABUF wsabuf; wsabuf.buf=new char[1000]; wsabuf.len=1000; memset(wsabuf.buf,0,1000); m_listensock=socket(AF_INET,SOCK_STREAM,0); SOCKADDR_IN m_addr; m_addr.sin_addr.S_un.S_addr=INADDR_ANY; m_addr.sin_family=AF_INET; m_addr.sin_port=htons(6000); bind(m_listensock,(SOCKADDR*)&m_addr,sizeof(SOCKADDR)); listen(m_listensock,5); RECVPARAM *p=new RECVPARAM; p->sock[0]=m_acceptsock; p->sock[1]=m_listensock; p->wsabuf.buf=wsabuf.buf; p->wsabuf.len=wsabuf.len; HANDLE h_thread=CreateThread(NULL,0,IOProc,(LPVOID)p,0,NULL); CloseHandle(h_thread); } DWORD WINAPI COVERLAPPEDDlg::IOProc(LPVOID lparam) { WSABUF wsabuf; DWORD dwRead; DWORD dwFlag=0; SOCKET s=((RECVPARAM*)lparam)->sock[0]; SOCKET sL=((RECVPARAM*)lparam)->sock[1]; wsabuf.buf=((RECVPARAM*)lparam)->wsabuf.buf; wsabuf.len=((RECVPARAM*)lparam)->wsabuf.len; s=accept(sL,NULL,NULL); if(s!=INVALID_SOCKET) AfxMessageBox("有一個用戶連接上了!"); EventArray[EventTotal]=WSACreateEvent(); ZeroMemory(&lp,sizeof(WSAOVERLAPPED)); lp.hEvent=EventArray[EventTotal]; wsabuf.buf=new char[1000]; wsabuf.len=1000; EventTotal++;//EventTotal=1了 memset(wsabuf.buf, 0, 1000); //把s變成阻塞的 u_long ul=0; ioctlsocket(s,FIONBIO,(u_long*)&ul); //發送一個接收數據請求，通常是返回ERROR的，這裏判斷在ERROR時 //如果是WSA_IO_PENDING則說明I/O操作正在進行，就接着執行後面的操作 //否則返回 if(WSARecv(s,&wsabuf,1,&dwRead,&dwFlag,&lp,NULL) ==NO_ERROR)//這時候重疊結構lp對應的事件對象受信了 { if(WSAGetLastError()!=WSA_IO_PENDING) { // 錯誤返回不是WSA_IO_PENDING，這時候可能是對方根本就 //沒發送數據，I/O操作沒有執行 AfxMessageBox("出錯!"); return 1; } } //開始進行重疊I/O的操作了 while(1) { //查詢哪個事件對象是受信的 int index=WSAWaitForMultipleEvents(EventTotal,EventArray,FALSE,WSA_INFINITE,FALSE); //把那個事件對象重置爲不受信狀態 WSAResetEvent(EventArray[index-index-WSA_WAIT_EVENT_0]); DWORD flag; DWORD byte; //判斷重疊調用的返回狀態 WSAGetOverlappedResult(s,&lp,&byte,FALSE,&flag); //對方已關閉則關閉套接字 if(byte==0) { AfxMessageBox("對方關閉連接2!"); closesocket(s); //釋放事件對象，注意索引 WSACloseEvent(EventArray[index-index-WSA_WAIT_EVENT_0]); return 1; } //如果上面檢查對方沒關閉則顯示接收到的數據 AfxMessageBox(wsabuf.buf); SOCKADDR_IN M_ADDR; int len=sizeof(SOCKADDR); //s=accept(sL,(SOCKADDR*)&M_ADDR,&len); flag=0; //重新把重疊結構清理 ZeroMemory(&lp,sizeof(WSAOVERLAPPED)); //再與剛剛被重置的事件對象關聯 lp.hEvent=EventArray[index-WSA_WAIT_EVENT_0]; //再發送另一個接收請求,解釋跟第一個一樣 if(WSARecv(s,&wsabuf,1,&dwRead,&flag,&lp,NULL)==NO_ERROR) { if(WSAGetLastError()!=WSA_IO_PENDING) { AfxMessageBox("出錯!"); return 1; } } } return 0; }

 

上面是MFC下實現的單套接字的情況，下面給出在控制檯下實現的多套接字情況，其實也不能說是“多”，因爲他每處理一個套接字都要創建一個線程，這顯然是不行的。

 

#include "stdio.h" #include "winsock2.h" #pragma comment(lib,"ws2_32.lib") typedef struct userInfo { SOCKET hSocket; // 主鍵:通信套接字 char szClientIP[16];// 自定義字段:客戶端地址 }USERINFO, * PUSERINFO; DWORD WINAPI IOProc(LPVOID lparam); int main( ) { PUSERINFO pUserInfo; SOCKET m_listensock; SOCKET m_acceptsock; int len; HANDLE hThread; // Start WinSock and create a listen socket. WSADATA wsadata; WSAStartup(MAKEWORD(2,2),&wsadata); m_listensock=socket(AF_INET,SOCK_STREAM,0); SOCKADDR_IN add; add.sin_addr.S_un.S_addr=INADDR_ANY; add.sin_family=AF_INET; add.sin_port=htons(6000); bind(m_listensock,(SOCKADDR*)&add,sizeof(SOCKADDR)); listen(m_listensock, 5); while(1) { len = sizeof(SOCKADDR); m_acceptsock = accept(m_listensock, (LPSOCKADDR)&add, &len); pUserInfo = (PUSERINFO)malloc(sizeof(userInfo)); pUserInfo->hSocket = m_acceptsock; // 注意這裏將連接的客戶端的IP地址，保存到了pUserInfo字段中了 strcpy(pUserInfo->szClientIP, inet_ntoa(add.sin_addr)); // 爲本次客戶請求產生子線程 hThread = CreateThread( NULL, 0, IOProc, (LPVOID)pUserInfo, // 將pUserInfo傳給子線程 0, NULL ); CloseHandle(hThread); } return 0; } DWORD WINAPI IOProc(LPVOID lpParam) { PUSERINFO pUserInfo = (PUSERINFO)lpParam; WSAOVERLAPPED Overlapped; WSABUF wsaBuf; char Buffer[1024]; BOOL bResult; int nResult; DWORD dwNumOfBytesRecved; DWORD dwBytesTransferred; DWORD dwFlags; ZeroMemory(&Overlapped, sizeof(WSAOVERLAPPED)); wsaBuf.buf = Buffer; wsaBuf.len = sizeof(Buffer); memset(wsaBuf.buf,0,wsaBuf.len); dwFlags = 0; nResult = WSARecv( pUserInfo->hSocket, // Receive socket &wsaBuf, // 指向WSABUF結構的指針 1, // WSABUF數組的個數 &dwNumOfBytesRecved, // 存放當WSARecv完成後所接收到的字節數 &dwFlags, // A pointer to flags &Overlapped, // A pointer to a WSAOVERLAPPED structure NULL // A pointer to the completion routine,this is NULL ); if ( nResult == SOCKET_ERROR && GetLastError() != WSA_IO_PENDING) { printf("WSARecv(..) failed./n"); free(pUserInfo); return -1; } while (TRUE) { bResult = WSAGetOverlappedResult( pUserInfo->hSocket, &Overlapped, &dwBytesTransferred, // 當一個同步I/O完成後,接收到的字節數 TRUE, // 等待I/O操作的完成 &dwFlags ); if (dwBytesTransferred == 0) { printf("客戶端已退出,將斷開與之的連接!/n"); closesocket(pUserInfo->hSocket); free(pUserInfo); break; } // 在這裏將接收到的數據進行處理 printf("Received from IP: %s./ndata: %s/n", pUserInfo->szClientIP, wsaBuf.buf); // 發送另外一個請求操作 ZeroMemory(&Overlapped, sizeof(WSAOVERLAPPED)); dwFlags = 0; nResult = WSARecv( pUserInfo->hSocket, // Receive socket &wsaBuf, // 指向WSABUF結構的指針 1, // WSABUF數組的個數 &dwNumOfBytesRecved, // 存放當WSARecv完成後所接收到的字節數 &dwFlags, // A pointer to flags &Overlapped, // A pointer to a WSAOVERLAPPED structure NULL // A pointer to the completion routine,this is NULL ); if ( nResult == SOCKET_ERROR && GetLastError() != WSA_IO_PENDING) { printf("WSARecv(..) failed./n"); free(pUserInfo); return -1; } } return 1; }