学步园

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<br /> {<br /> // TODO: Add your control notification handler code here</p> <p> WSABUF wsabuf;<br /> wsabuf.buf=new char[1000];<br /> wsabuf.len=1000;<br /> memset(wsabuf.buf,0,1000);<br /> m_listensock=socket(AF_INET,SOCK_STREAM,0);</p> <p> SOCKADDR_IN m_addr;<br /> m_addr.sin_addr.S_un.S_addr=INADDR_ANY;<br /> m_addr.sin_family=AF_INET;<br /> m_addr.sin_port=htons(6000);<br /> bind(m_listensock,(SOCKADDR*)&m_addr,sizeof(SOCKADDR));</p> <p> listen(m_listensock,5);</p> <p> RECVPARAM *p=new RECVPARAM;<br /> p->sock[0]=m_acceptsock;<br /> p->sock[1]=m_listensock;<br /> p->wsabuf.buf=wsabuf.buf;<br /> p->wsabuf.len=wsabuf.len;<br /> HANDLE h_thread=CreateThread(NULL,0,IOProc,(LPVOID)p,0,NULL);<br /> CloseHandle(h_thread);</p> <p>}</p> <p>DWORD WINAPI COVERLAPPEDDlg::IOProc(LPVOID lparam)<br /> {<br /> WSABUF wsabuf;<br /> DWORD dwRead;<br /> DWORD dwFlag=0;</p> <p> SOCKET s=((RECVPARAM*)lparam)->sock[0];<br /> SOCKET sL=((RECVPARAM*)lparam)->sock[1];<br /> wsabuf.buf=((RECVPARAM*)lparam)->wsabuf.buf;<br /> wsabuf.len=((RECVPARAM*)lparam)->wsabuf.len;</p> <p> s=accept(sL,NULL,NULL);<br /> if(s!=INVALID_SOCKET)<br /> AfxMessageBox("有一个用户连接上了!");</p> <p> EventArray[EventTotal]=WSACreateEvent();</p> <p> ZeroMemory(&lp,sizeof(WSAOVERLAPPED));</p> <p> lp.hEvent=EventArray[EventTotal];</p> <p> wsabuf.buf=new char[1000];<br /> wsabuf.len=1000;</p> <p> EventTotal++;//EventTotal=1了<br /> memset(wsabuf.buf, 0, 1000);</p> <p> //把s变成阻塞的<br /> u_long ul=0;<br /> ioctlsocket(s,FIONBIO,(u_long*)&ul);<br /> //发送一个接收数据请求，通常是返回ERROR的，这里判断在ERROR时<br /> //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<br /> //否则返回<br /> if(WSARecv(s,&wsabuf,1,&dwRead,&dwFlag,&lp,NULL)<br /> ==NO_ERROR)//这时候重叠结构lp对应的事件对象受信了<br /> {<br /> if(WSAGetLastError()!=WSA_IO_PENDING)<br /> {<br /> // 错误返回不是WSA_IO_PENDING，这时候可能是对方根本就<br /> //没发送数据，I/O操作没有执行<br /> AfxMessageBox("出错!");<br /> return 1;<br /> }</p> <p> }</p> <p> //开始进行重叠I/O的操作了<br /> while(1)<br /> {<br /> //查询哪个事件对象是受信的<br /> int index=WSAWaitForMultipleEvents(EventTotal,EventArray,FALSE,WSA_INFINITE,FALSE);<br /> //把那个事件对象重置为不受信状态<br /> WSAResetEvent(EventArray[index-index-WSA_WAIT_EVENT_0]);<br /> DWORD flag;<br /> DWORD byte;<br /> //判断重叠调用的返回状态<br /> WSAGetOverlappedResult(s,&lp,&byte,FALSE,&flag);<br /> //对方已关闭则关闭套接字<br /> if(byte==0)<br /> {</p> <p> AfxMessageBox("对方关闭连接2!");<br /> closesocket(s);<br /> //释放事件对象，注意索引<br /> WSACloseEvent(EventArray[index-index-WSA_WAIT_EVENT_0]);<br /> return 1;<br /> }</p> <p> //如果上面检查对方没关闭则显示接收到的数据<br /> AfxMessageBox(wsabuf.buf);</p> <p> SOCKADDR_IN M_ADDR;<br /> int len=sizeof(SOCKADDR);<br /> //s=accept(sL,(SOCKADDR*)&M_ADDR,&len);</p> <p> flag=0;<br /> //重新把重叠结构清理<br /> ZeroMemory(&lp,sizeof(WSAOVERLAPPED));<br /> //再与刚刚被重置的事件对象关联<br /> lp.hEvent=EventArray[index-WSA_WAIT_EVENT_0];</p> <p> //再发送另一个接收请求,解释跟第一个一样<br /> if(WSARecv(s,&wsabuf,1,&dwRead,&flag,&lp,NULL)==NO_ERROR)<br /> {<br /> if(WSAGetLastError()!=WSA_IO_PENDING)<br /> {<br /> AfxMessageBox("出错!");<br /> return 1;<br /> }<br /> }</p> <p> }<br /> return 0;<br /> }

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"<br /> #include "winsock2.h"<br /> #pragma comment(lib,"ws2_32.lib")</p> <p>typedef struct userInfo<br /> {<br /> SOCKET hSocket; // 主键:通信套接字<br /> char szClientIP[16];// 自定义字段:客户端地址</p> <p>}USERINFO, * PUSERINFO;</p> <p>DWORD WINAPI IOProc(LPVOID lparam);<br /> int main( )<br /> {<br /> PUSERINFO pUserInfo;<br /> SOCKET m_listensock;<br /> SOCKET m_acceptsock;</p> <p> int len;<br /> HANDLE hThread; </p> <p> // Start WinSock and create a listen socket.</p> <p> WSADATA wsadata;<br /> WSAStartup(MAKEWORD(2,2),&wsadata);<br /> m_listensock=socket(AF_INET,SOCK_STREAM,0);</p> <p> SOCKADDR_IN add;<br /> add.sin_addr.S_un.S_addr=INADDR_ANY;<br /> add.sin_family=AF_INET;<br /> add.sin_port=htons(6000);<br /> bind(m_listensock,(SOCKADDR*)&add,sizeof(SOCKADDR));</p> <p> listen(m_listensock, 5);<br /> while(1)<br /> {<br /> len = sizeof(SOCKADDR);<br /> m_acceptsock = accept(m_listensock, (LPSOCKADDR)&add, &len);</p> <p> pUserInfo = (PUSERINFO)malloc(sizeof(userInfo));<br /> pUserInfo->hSocket = m_acceptsock;<br /> // 注意这里将连接的客户端的IP地址，保存到了pUserInfo字段中了<br /> strcpy(pUserInfo->szClientIP, inet_ntoa(add.sin_addr));</p> <p> // 为本次客户请求产生子线程<br /> hThread = CreateThread(<br /> NULL,<br /> 0,<br /> IOProc,<br /> (LPVOID)pUserInfo, // 将pUserInfo传给子线程<br /> 0,<br /> NULL<br /> );<br /> CloseHandle(hThread);<br /> }<br /> return 0;<br /> }</p> <p>DWORD WINAPI IOProc(LPVOID lpParam)<br /> {<br /> PUSERINFO pUserInfo = (PUSERINFO)lpParam;<br /> WSAOVERLAPPED Overlapped;<br /> WSABUF wsaBuf;<br /> char Buffer[1024];<br /> BOOL bResult;<br /> int nResult;<br /> DWORD dwNumOfBytesRecved;<br /> DWORD dwBytesTransferred;<br /> DWORD dwFlags;</p> <p> ZeroMemory(&Overlapped, sizeof(WSAOVERLAPPED));<br /> wsaBuf.buf = Buffer;<br /> wsaBuf.len = sizeof(Buffer);</p> <p> memset(wsaBuf.buf,0,wsaBuf.len);</p> <p> dwFlags = 0;<br /> nResult = WSARecv(<br /> pUserInfo->hSocket, // Receive socket<br /> &wsaBuf, // 指向WSABUF结构的指针<br /> 1, // WSABUF数组的个数<br /> &dwNumOfBytesRecved, // 存放当WSARecv完成后所接收到的字节数<br /> &dwFlags, // A pointer to flags<br /> &Overlapped, // A pointer to a WSAOVERLAPPED structure<br /> NULL // A pointer to the completion routine,this is NULL<br /> );<br /> if ( nResult == SOCKET_ERROR && GetLastError() != WSA_IO_PENDING)<br /> {<br /> printf("WSARecv(..) failed./n");<br /> free(pUserInfo);<br /> return -1;<br /> }</p> <p> while (TRUE)<br /> {<br /> bResult = WSAGetOverlappedResult(<br /> pUserInfo->hSocket,<br /> &Overlapped,<br /> &dwBytesTransferred, // 当一个同步I/O完成后,接收到的字节数<br /> TRUE, // 等待I/O操作的完成<br /> &dwFlags<br /> );</p> <p> if (dwBytesTransferred == 0)<br /> {<br /> printf("客户端已退出,将断开与之的连接!/n");<br /> closesocket(pUserInfo->hSocket);<br /> free(pUserInfo);<br /> break;<br /> }</p> <p> // 在这里将接收到的数据进行处理<br /> printf("Received from IP: %s./ndata: %s/n", pUserInfo->szClientIP, wsaBuf.buf); </p> <p> // 发送另外一个请求操作<br /> ZeroMemory(&Overlapped, sizeof(WSAOVERLAPPED));</p> <p> dwFlags = 0;<br /> nResult = WSARecv(<br /> pUserInfo->hSocket, // Receive socket<br /> &wsaBuf, // 指向WSABUF结构的指针<br /> 1, // WSABUF数组的个数<br /> &dwNumOfBytesRecved, // 存放当WSARecv完成后所接收到的字节数<br /> &dwFlags, // A pointer to flags<br /> &Overlapped, // A pointer to a WSAOVERLAPPED structure<br /> NULL // A pointer to the completion routine,this is NULL<br /> );<br /> if ( nResult == SOCKET_ERROR && GetLastError() != WSA_IO_PENDING)<br /> {<br /> printf("WSARecv(..) failed./n");<br /> free(pUserInfo);<br /> return -1;<br /> }<br /> }</p> <p> return 1;<br /> }