Windows网络编程 2 【转】

Windows网络编程使用winsock。Winsock是一个基于Socket模型的API，在Windows系统中广泛使用。
使用Winsock进行网络编程需要包含头文件Winsock2.h，需要使用库ws2_32.lib，包含方法：可以使用语句来告诉编译器连接该库
#pragma comment(lib, “ws2_32.lib”);
如果使用VS，可以通过“项目” --> “XX属性”--> “连接器”-->“输入”--> “附加依赖项”添加ws2_32.lib。 （XX为当前工程名）

● 面向连接的C/S程序工程流程图

使用Winsock API编制的网络应用程序中，在调用任何一个Winsock函数之前都必须检查协议栈安装情况，使用函数WSAStartup()完成操作。
● 一个服务端的例子

void server::startServer()
{
    WORD wVersionRequested;
    WSADATA wsaData;
    wVersionRequested=MAKEWORD(2,2);
    if(WSAStartup(wVersionRequested,&wsaData)!=0)
    {
        //Winsock初始化错误
        msgBox.exec();
        return;
    }
    if(wsaData.wVersion!=wVersionRequested)
    {
        //Winsock版本不匹配        
        WSACleanup();
        return;
    }

    if ((m_sk = socket(AF_INET, SOCK_STREAM, 0)) == SOCKET_ERROR)
    {        
        WSACleanup();
        return;
    }
    bool ok;
    unsigned short port = ui.portLineEdit->text().toInt(&ok, 10);
    if (ok == false)
    {
        //端口输入错误
        closesocket(m_sk);
        m_sk = -1;
        WSACleanup();
        return;
    }

    sockaddr_in addr;
    addr.sin_family = AF_INET; //使用互联网际协议，即IP协议
    addr.sin_port = htons(port);
    addr.sin_addr.S_un.S_addr = htonl(INADDR_ANY);

    if (bind(m_sk, (sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
    {
        //绑定端口失败

        closesocket(m_sk);
        m_sk = -1;
        WSACleanup();
        return;
    }

    if (listen(m_sk, 10) == SOCKET_ERROR)
    {
        //监听端口失败
        closesocket(m_sk);
        m_sk = -1;
        WSACleanup();
        return;
    }
    updateMsgRecs(tr("等待连接..."));
    //创建线程去等待连接
    HANDLE h = CreateThread(NULL, 0, &server::acceptProc, (LPVOID)this, 0, 0);
    if (h == NULL)
    {        
        closesocket(m_sk);
        m_sk = -1;
        WSACleanup();
        return;        
    }
    CloseHandle(h);
}

● 监听线程函数

DWORD WINAPI server::acceptProc(LPVOID lpParamter)
{
    /*server *p_server = (server *)lpParamter;
    sockaddr_in client_addr;
    int len = sizeof(client_addr);
    char msgBuff[256];
    int sk;
    while (1)
    {
        if ((sk = ::accept(p_server->sk(), (sockaddr*)&client_addr, &len) )== SOCKET_ERROR)
        {
            emit p_server->haveNewMsg(QObject::tr("accept 出错"));
            break;
        }
        
        sprintf(msgBuff, "新连接来自%s", inet_ntoa(client_addr.sin_addr));
        emit p_server->haveNewMsg(msgBuff);
        emit p_server->newClient(inet_ntoa(client_addr.sin_addr), sk);
    }*/

    server *p_server = (server *)lpParamter;
    int client[FD_SETSIZE];
    fd_set allset, rset;
    sockaddr_in client_addr;
    int len;
    int clientfd;
    int sockfd;

    int i;
    for (i=0; i<FD_SETSIZE; i++)
        client[i] = -1;
    FD_ZERO(&allset);
    int listenfd = p_server->sk();
    FD_SET(listenfd, &allset);

    int nready;
    int maxfd = listenfd;
    int maxi = -1;
    char buff[MAX_LEN+1];

    while (1)
    {
        rset = allset;
        nready = select(maxfd+1, &rset, NULL, NULL, NULL);
        if (FD_ISSET(listenfd, &rset)) //new connection
        {
            len = sizeof(client_addr);
            if ( (clientfd = ::accept(p_server->sk(), (sockaddr*)&client_addr, &len)) == SOCKET_ERROR)
            {
                emit p_server->haveNewMsg(QObject::tr("accept 出错"));
                break;
            }
            //找出client数组中第一个为-1的单元存放已经连接的socket
            for (i=0; i<FD_SETSIZE; i++)
            {
                if (client[i] <0)
                {
                    client[i] = clientfd;
                    break;
                }
            }
            if (i == FD_SETSIZE)
            {
                emit p_server->haveNewMsg(QObject::tr("error: too many clients!"));
                break;
            }
            //sprintf(buff, "新连接来自%s", inet_ntoa(client_addr.sin_addr));
            //emit p_server->haveNewMsg(buff);
            emit p_server->newClient(inet_ntoa(client_addr.sin_addr), clientfd);
            FD_SET(clientfd, &allset);
            if (clientfd > maxfd)
                maxfd = clientfd;
            if (i>maxi)
                maxi = i;
            if (--nready <= 0)
                continue;
        }
        for (i=0; i<=maxi; i++)
        {
            if ( (sockfd = client[i]) < 0)
                continue;
            if (FD_ISSET(sockfd, &rset))
            {
                int n;
                //客户端已经关闭连接
                if ( (n = recv(sockfd, buff, MAX_LEN, 0 )) <= 0)
                {
                    closesocket(sockfd);
                    FD_CLR(sockfd, &allset);
                    client[i] = -1;
                    emit p_server->haveNewMsg(QObject::tr("client closed"));
                    emit p_server->sClientClose(sockfd);
                }
                else //收到数据
                {
                    buff[n] = 0;
                    emit p_server->haveNewMsg( buff, sockfd);
                    if (--nready <= 0)
                        break;
                }
            }
        } //for (i=0; i<=maxi; i++)
    }
    return 0;
}

●  一个客户端的例子

void client::connectServer()
{
    WORD wVersionRequested;
    WSADATA wsaData;
    wVersionRequested=MAKEWORD(2,2);
    if(WSAStartup(wVersionRequested,&wsaData)!=0)
    {
        //Winsock初始化错误
        QMessageBox msgBox(QMessageBox::Warning, tr("错误"), tr("Winsock初始化错误"), QMessageBox::Ok, 0);
        msgBox.exec();
        return;
    }
    if(wsaData.wVersion!=wVersionRequested)
    {
        //Winsock版本不匹配
        QMessageBox msgBox(QMessageBox::Warning, tr("错误"), tr("Winsock版本不匹配"), QMessageBox::Ok, 0);
        msgBox.exec();
        WSACleanup();
        return;
    }

    if ((m_sk = socket(AF_INET, SOCK_STREAM, 0)) == SOCKET_ERROR)
    {
        QMessageBox msgBox(QMessageBox::Warning, tr("错误"), tr("创建socket失败"), QMessageBox::Ok, 0);
        msgBox.exec();
        WSACleanup();
        return;
    }

    sockaddr_in addr;
    addr.sin_family = AF_INET;

    bool ok;
    unsigned short port = ui.portLineEdit->text().toInt(&ok, 10);
    if (ok == false)
    {
        QMessageBox msgBox(QMessageBox::Warning, tr("错误"), tr("端口输入错误"), QMessageBox::Ok, 0);
        msgBox.exec();
        closesocket(m_sk);
        m_sk = -1;
        WSACleanup();
        return;
    }
    addr.sin_port  = htons(port);
    addr.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");

    if (0 == ::connect(m_sk, (sockaddr *)&addr, sizeof(addr)))
    {
        updateMsgRecs(tr("连接成功..."));
        HANDLE h = CreateThread(NULL, 0, &client::recvProc, (LPVOID)this, 0, 0);
        CloseHandle(h);
    }
    else
    {
        QMessageBox msgBox(QMessageBox::Warning, tr("错误"), tr("连接出错"), QMessageBox::Ok, 0);
        msgBox.exec();
        closesocket(m_sk);
        m_sk = -1;
        WSACleanup();
        
    }
}

●  winsock APIs

网络连接函数
socket　创建套接字
bind　绑定本机端口
connect　建立连接
listen　监听端口
accept　接受连接
recv, recvfrom　数据接收
send, sendto　数据发送
close, shutdown　关闭套接字
转换函数
inet_addr()　点分十进制数表示的IP地址转换为网络字节序的IP地址
inet_ntoa()　网络字节序的IP地址转换为点分十进制数表示的IP地址
字节顺序转换函数
htonl　4字节主机字节序转换为网络字节序
ntohl　 4字节网络字节序转换为主机字节序
htons　2字节主机字节序转换为网络字节序
ntohs　2字节网络字节序转换为主机字节序
网络信息检索函数
gethostname　获得主机名
getpeername　获得与套接口相连的远程协议地址
getsockname　获得套接口本地协议地址
gethostbyname　根据主机名取得主机信息
gethostbyaddr　根据主机地址取得主机信息
getprotobyname　根据协议名取得主机协议信息
getprotobynumber　根据协议号取得主机协议信息
getservbyname　根据服务名取得相关服务信息
getservbyport　根据端口号取得相关服务信息
getsockopt/setsockopt　获取/设置一个套接口选项
ioctlsocket　设置套接口的工作方式