int Receive(SOCKET fd, char *szText, int len)
{int cnt;int rc;cnt = len;while(cnt>0){rc= recv(fd, szText, cnt, 0);if(rc == SOCKET_ERROR){return -1;}if(rc == 0){return len-cnt;}szText += rc;cnt -= rc;}return len;
}
int Send(SOCKET fd, char *szText, int len)
{int cnt;int rc;cnt = len;while(cnt > 0){rc = send(fd, szText, cnt, 0);if(rc == SOCKET_ERROR){return -1;}if(rc == 0){return len-cnt;}szText += rc;cnt -= rc;}return len;
}

#define DEFAULT_PORT 2000
void CServerDlg::OnStart()
{sockaddr_in local;DWORDdwThreadID = 0;local.sin_family = AF_INET;//设置的端口为DEFAULT_PORT。local.sin_port = htons(DEFAULT_PORT);//IP地址设置成INADDR_ANY,让系统自动获取本机的IP地址。local.sin_addr.S_un.S_addr = INADDR_ANY;//初始化Socketm_Listening = socket(AF_INET,SOCK_STREAM,0);if(m_Listening == INVALID_SOCKET){return ;}//将本地地址绑定到所创建的套接字上if(bind(m_Listening, (LPSOCKADDR) & local, sizeof(local)) == SOCKET_ERROR ){closesocket(m_Listening);return ;}//创建监听线程，这样也能响应界面上操作。m_hListenThread = ::CreateThread(NULL, 0, ListenThread, this, 0, &dwThreadID);m_StartBtn.EnableWindow(FALSE);m_StopBtn.EnableWindow(TRUE);
}
//监听线程函数：
DWORD WINAPI CServerDlg::ListenThread(LPVOID lpparam)
{CServerDlg* pDlg = (CServerDlg*)lpparam;if(pDlg == NULL) return 0;SOCKET  Listening = pDlg->m_Listening;//开始监听是否有客户端连接。if(listen(Listening,40) == SOCKET_ERROR){return 0;}char szBuf[MAX_PATH];//初始化memset(szBuf,0,MAX_PATH);while(1){SOCKET ConnectSocket;sockaddr_in ClientAddr;int nLen = sizeof(sockaddr);//阻塞直到有客户端连接，不然多浪费CPU资源。ConnectSocket = accept(Listening,(sockaddr*)&ClientAddr,&nLen);//得到客户端的IP地址。char *pAddrname = inet_ntoa(ClientAddr.sin_addr);pDlg->Receive(ConnectSocket,szBuf,100);//界面上显示请求数据。pDlg->SetRequestText(szBuf);strcat(szBuf, " :我是老猫，收到（");strcat(szBuf, pAddrname);strcat(szBuf, "）");//向客户端发送回应数据pDlg->Send(ConnectSocket,szBuf,100);}return 0;
}

#define DEFAULT_PORT 2000
void CClientDlg::OnSend()
{DWORDdwIP = 0;      TCHAR szText[MAX_PATH];memset(szText, 0, MAX_PATH);m_IP.GetWindowText(szText, MAX_PATH);//把字符串形式的IP地址转成IN_ADDR结构需要的形式。dwIP = inet_addr(szText);m_RequestEdit.GetWindowText(szText, MAX_PATH); sockaddr_in local;SOCKET socketTmp;//必须是AF_INET,表示该socket在Internet域中进行通信local.sin_family = AF_INET;//端口号local.sin_port = htons(DEFAULT_PORT);//服务器的IP地址。local.sin_addr.S_un.S_addr = dwIP;      ////初始化SocketsocketTmp = socket(AF_INET, SOCK_STREAM, 0);//连接服务器if(connect(socketTmp, (LPSOCKADDR) & local, sizeof(local)) < 0){closesocket(socketTmp);MessageBox("连接服务器失败。");return ;}//发送请求，为简单只发100字节，在服务器端也规定100字节。Send(socketTmp, szText, 100);//读取服务器端返回的数据。memset(szText,0,MAX_PATH);//接收服务器端的回应。Receive(socketTmp, szText, 100); TCHAR szMessage[MAX_PATH];memset(szMessage, 0, MAX_PATH);strcat(szMessage, szText);//界面上显示回应数据。m_ReplyBtn.SetWindowText(szMessage);closesocket(socketTmp);
}