支持ipV6和ipV4的客户端编程

   ipv4和ipv6在socket初始化的时候是不一样的。

  ipv4 socket初始化：

int CClient::InitSocket(CString strIP, short portNum)
{
    WSADATA wsd; 
    SOCKADDR_IN servAddr; 
    int retVal; 
    //初始化套结字动态库  
    if (WSAStartup(MAKEWORD(2, 2), &wsd) != 0)
    {
        return -1;
    }
    //创建套接字  
    m_sHost = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (INVALID_SOCKET == m_sHost)
    {
        WSACleanup();//释放套接字资源  
        return  -1;
    }

    //设置服务器地址  
    servAddr.sin_family = AF_INET;
    servAddr.sin_addr.s_addr = inet_addr((LPCTSTR)strIP);
    servAddr.sin_port = htons(portNum);
    int nServAddlen = sizeof(servAddr);

    //设置非阻塞方式连接
    unsigned long ul = 1;
    retVal = ioctlsocket(m_sHost, FIONBIO, (unsigned long*)&ul);
    if (retVal == SOCKET_ERROR) return 0;

    //连接服务器  
    retVal = connect(m_sHost, (LPSOCKADDR)&servAddr, sizeof(servAddr));

    if (retVal == 0)
    {

    }
    else
    {
        int iErr = GetLastError();
        if (WSAEWOULDBLOCK == iErr)
        {
            struct timeval timeout;
            fd_set r;

            FD_ZERO(&r);
            FD_SET(m_sHost, &r);
            timeout.tv_sec = 1; 
            timeout.tv_usec = 0;
            retVal = select(m_sHost + 1, NULL, &r, NULL, &timeout);
            if (retVal <= 0)
            {
                closesocket(m_sHost); //关闭套接字  
                WSACleanup(); //释放套接字资源  
                return -1;
            }
        }
    }

    //退出  
    return 0;
}

ipv6 socket初始化：

int CClient::InitSocket(CString strIP, short portNum)
{
    WSADATA wsd;
    struct sockaddr_in6 servAddr_in6; 
    int retVal; 
    int nServAddlen;
    
    //初始化套结字动态库  
    if (WSAStartup(MAKEWORD(2, 2), &wsd) != 0)
    {
        return -1;
    }

    sprintf_s(m_szIP, sizeof(m_szIP), strIP);

    memset(&servAddr_in6, 0, sizeof(struct sockaddr_in6));

    //创建套接字  
    m_sHost = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);
    if (INVALID_SOCKET == m_sHost)
    {
        return  -1;
    }

    //设置服务器地址  
    servAddr_in6.sin6_family = AF_INET6;

    if (!inet_pton(AF_INET6, m_szIP, &servAddr_in6.sin6_addr.s6_addr))
    {
        closesocket(m_sHost); //关闭套接字 
        WSACleanup(); //释放套接字资源 
        return  -1;
    }
    
    //设置非阻塞方式连接
    unsigned long ul = 1;
    retVal = ioctlsocket(m_sHost, FIONBIO, (unsigned long*)&ul);
    if (retVal == SOCKET_ERROR) return 0;
    
    servAddr_in6.sin6_port = htons(portNum);
    nServAddlen = sizeof(servAddr_in6);
    //连接服务器  
    retVal = connect(m_sHost, (LPSOCKADDR)&servAddr_in6, (socklen_t)nServAddlen);

   if (retVal == 0)
    {

    }
    else
    {
        int iErr = GetLastError();
        if (WSAEWOULDBLOCK == iErr)
        {
            struct timeval timeout;
            fd_set r;

            FD_ZERO(&r);
            FD_SET(m_sHost, &r);
            timeout.tv_sec = 1; 
            timeout.tv_usec = 0;
            retVal = select(m_sHost + 1, NULL, &r, NULL, &timeout);
            if (retVal <= 0)
            {
                closesocket(m_sHost); //关闭套接字  
                WSACleanup(); //释放套接字资源  
                return -1;
            }
        }
    }

    //退出  
    return 0;
}

将上面的逻辑合二为一：

int CClient::InitSocket(CString strIP, short portNum)
{
    WSADATA wsd;
    struct sockaddr_in6 servAddr_in6;
    SOCKADDR_IN servAddr;
    int retVal;
    int nServAddlen;
    
    //初始化套结字动态库  
    if (WSAStartup(MAKEWORD(2, 2), &wsd) != 0)
    {
        return -1;
    }

    sprintf_s(m_szIP, sizeof(m_szIP), strIP);

    memset(&servAddr, 0, sizeof(servAddr));
    memset(&servAddr_in6, 0, sizeof(struct sockaddr_in6));

    //设置非阻塞方式连接
    unsigned long ul = 1;
    retVal = ioctlsocket(m_sHost, FIONBIO, (unsigned long*)&ul);
    if (retVal == SOCKET_ERROR) return 0;
    if (TRUE == is_string_ipaddr_ipv4(m_szIP, &servAddr.sin_addr))
    {
        //创建套接字  
        m_sHost = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
        if (INVALID_SOCKET == m_sHost)
        {
            WSACleanup();//释放套接字资源  
            return  -1;
        }

        //设置服务器地址  
        servAddr.sin_family = AF_INET;
        servAddr.sin_addr.s_addr = inet_addr(m_szIP);
        servAddr.sin_port = htons(portNum);
        nServAddlen = sizeof(servAddr);
        //连接服务器  
        retVal = connect(m_sHost, (LPSOCKADDR)&servAddr, (socklen_t)nServAddlen);
    }
    else
    {
        //创建套接字  
        m_sHost = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);
        if (INVALID_SOCKET == m_sHost)
        {
            return  -1;
        }

        //设置服务器地址  
        servAddr_in6.sin6_family = AF_INET6;

        if (!inet_pton(AF_INET6, m_szIP, &servAddr_in6.sin6_addr.s6_addr))
        {
            closesocket(m_sHost); //关闭套接字 
            WSACleanup(); //释放套接字资源 
            return  -1;
        }
        servAddr_in6.sin6_port = htons(portNum);
        nServAddlen = sizeof(servAddr_in6);
        //连接服务器  
        retVal = connect(m_sHost, (LPSOCKADDR)&servAddr_in6, (socklen_t)nServAddlen);
    }

   if (retVal == 0)
    {

    }
    else
    {
        int iErr = GetLastError();
        if (WSAEWOULDBLOCK == iErr)
        {
            struct timeval timeout;
            fd_set r;

            FD_ZERO(&r);
            FD_SET(m_sHost, &r);
            timeout.tv_sec = 1;
            timeout.tv_usec = 0;
            retVal = select(m_sHost + 1, NULL, &r, NULL, &timeout);
            if (retVal <= 0)
            {
                closesocket(m_sHost); //关闭套接字  
                WSACleanup(); //释放套接字资源  
                return -1;
            }
        }
    }

    //退出  
    return 0;
}

判断一个ip是不是ipv4的

/*判断传入的字符串是否为ipv4格式的
*/
bool CClient::is_string_ipaddr_ipv4(const char* str_ipv4, struct in_addr *ip)
{
    int32 ret = -1;
    struct in_addr tmp_ip;

    memset(&tmp_ip, 0, sizeof(struct in_addr));

    if (NULL == str_ipv4)
    {
        return false;
    }

    if (0 == *str_ipv4)
    {
        return false;
    }

    ret = inet_pton(AF_INET, str_ipv4, &tmp_ip);
    if (0 == ret)
    {
        return false;
    }
    else if (ret < 0)
    {
        return false;
    }
    else
    {
        if (NULL != ip)
        {
            memcpy(ip, (void *)&tmp_ip, sizeof(struct in_addr));
        }

        return true;
    }
}