套接字之重叠I/O模型

刚刚把重叠I/O套接字理解了一点，于是在此做个笔记，给出一个重叠I/O处理单个套接字的程序。

 

这个程序是TCP的服务器端程序。该程序只能接收一个客户端的连接，循环发送信息，以及该客户端退出时服务器端得到响应。

 

套接字库初始化等代码省略了，只包含一个监听部分和一个处理I/O部分的代码。如下：

 

void COVERLAPPEDDlg::OnButton1() //开启服务器按钮 { // 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("有一个用户连接上了!"); 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变成阻塞的 u_long ul=0; ioctlsocket(s,FIONBIO,(u_long*)&ul); //发送一个接收数据请求，通常是返回ERROR的，这里判断在ERROR时 //如果是WSA_IO_PENDING则说明I/O操作正在进行，就接着执行后面的操作 //否则返回 if(WSARecv(s,&wsabuf,1,&dwRead,&dwFlag,&lp,NULL) ==NO_ERROR)//这时候重叠结构lp对应的事件对象受信了 { if(WSAGetLastError()!=WSA_IO_PENDING) { // 错误返回不是WSA_IO_PENDING，这时候可能是对方根本就 //没发送数据，I/O操作没有执行 AfxMessageBox("出错!"); return 1; } } //开始进行重叠I/O的操作了 while(1) { //查询哪个事件对象是受信的 int index=WSAWaitForMultipleEvents(EventTotal,EventArray,FALSE,WSA_INFINITE,FALSE); //把那个事件对象重置为不受信状态 WSAResetEvent(EventArray[index-index-WSA_WAIT_EVENT_0]); DWORD flag; DWORD byte; //判断重叠调用的返回状态 WSAGetOverlappedResult(s,&lp,&byte,FALSE,&flag); //对方已关闭则关闭套接字 if(byte==0) { AfxMessageBox("对方关闭连接2!"); closesocket(s); //释放事件对象，注意索引 WSACloseEvent(EventArray[index-index-WSA_WAIT_EVENT_0]); return 1; } //如果上面检查对方没关闭则显示接收到的数据 AfxMessageBox(wsabuf.buf); SOCKADDR_IN M_ADDR; int len=sizeof(SOCKADDR); //s=accept(sL,(SOCKADDR*)&M_ADDR,&len); flag=0; //重新把重叠结构清理 ZeroMemory(&lp,sizeof(WSAOVERLAPPED)); //再与刚刚被重置的事件对象关联 lp.hEvent=EventArray[index-WSA_WAIT_EVENT_0]; //再发送另一个接收请求,解释跟第一个一样 if(WSARecv(s,&wsabuf,1,&dwRead,&flag,&lp,NULL)==NO_ERROR) { if(WSAGetLastError()!=WSA_IO_PENDING) { AfxMessageBox("出错!"); return 1; } } } return 0; }

 

上面是MFC下实现的单套接字的情况，下面给出在控制台下实现的多套接字情况，其实也不能说是“多”，因为他每处理一个套接字都要创建一个线程，这显然是不行的。

 

#include "stdio.h" #include "winsock2.h" #pragma comment(lib,"ws2_32.lib") typedef struct userInfo { SOCKET hSocket; // 主键:通信套接字 char szClientIP[16];// 自定义字段:客户端地址 }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; // 注意这里将连接的客户端的IP地址，保存到了pUserInfo字段中了 strcpy(pUserInfo->szClientIP, inet_ntoa(add.sin_addr)); // 为本次客户请求产生子线程 hThread = CreateThread( NULL, 0, IOProc, (LPVOID)pUserInfo, // 将pUserInfo传给子线程 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结构的指针 1, // WSABUF数组的个数 &dwNumOfBytesRecved, // 存放当WSARecv完成后所接收到的字节数 &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, // 当一个同步I/O完成后,接收到的字节数 TRUE, // 等待I/O操作的完成 &dwFlags ); if (dwBytesTransferred == 0) { printf("客户端已退出,将断开与之的连接!/n"); closesocket(pUserInfo->hSocket); free(pUserInfo); break; } // 在这里将接收到的数据进行处理 printf("Received from IP: %s./ndata: %s/n", pUserInfo->szClientIP, wsaBuf.buf); // 发送另外一个请求操作 ZeroMemory(&Overlapped, sizeof(WSAOVERLAPPED)); dwFlags = 0; nResult = WSARecv( pUserInfo->hSocket, // Receive socket &wsaBuf, // 指向WSABUF结构的指针 1, // WSABUF数组的个数 &dwNumOfBytesRecved, // 存放当WSARecv完成后所接收到的字节数 &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; }