VC++ Windows 平台通过QOS2库函数设置Socket DSCP（IP_TOS）参数选项

本体提供的函数实现，只能对于TCP生效，UDP没法生效，看文档没搞明白，有了解UDP怎么设置DSCP的童鞋，可以在评论区给予答复。

用法是这样的，每个TCP在建立链接后，立即创建这个QOSS的实例，当然也可以在链接前，但在连接前有一定限制就是说，你必须在连接前把IP+PORT地址传进去，链接建立后在创建QOS就不需要传入IP+PORT地址。

同时，在关联的TCP链接关闭时需要销毁这个，否则就会产生QOS2内核句柄资源泄漏。

DSCP值26，就等于 IP_TOS: 0x68，即FLASH，[IPTOS_LOWDELAY] 宏的效果【MACOS/LINUX】上，Windows 平台被微软禁用支援了。

头文件声明：

        class QoSS final
        {
        public:
            QoSS(int fd) noexcept;
            ~QoSS() noexcept;
 
        public:
            static std::shared_ptr<QoSS>            New(int fd, const boost::asio::ip::address& host, int port) noexcept { return New(fd, host, port, false); }
            static std::shared_ptr<QoSS>            New(int fd) noexcept { return New(fd, boost::asio::ip::address_v4::any(), 0, true); }
 
        private:
            static std::shared_ptr<QoSS>            New(int fd, const boost::asio::ip::address& host, int port, bool noaddress) noexcept;
 
        private:
            int                                     fd_ = -1;
            void*                                   h_  = NULL;
            DWORD                                   f_  = 0;
        };

源文件：

        QoSS::QoSS(int fd) noexcept
            : fd_(fd)
            , h_(NULL)
            , f_(NULL)
        {
 
        }
 
        QoSS::~QoSS() noexcept
        {
            if (NULL != h_)
            {
                if (f_ != 0)
                {
                    QOSRemoveSocketFromFlow(h_, fd_, f_, 0);
                }
 
                QOSCloseHandle(h_);
            }
        }
 
        std::shared_ptr<QoSS> QoSS::New(int fd, const boost::asio::ip::address& host, int port, bool noaddress) noexcept
        {
            if (fd == INVALID_SOCKET)
            {
                return NULL;
            }
 
            std::shared_ptr<QoSS> qos = make_shared_object<QoSS>(fd);
            if (NULL == qos)
            {
                return NULL;
            }
 
            QOS_VERSION ver = { 1, 0 };
            if (!QOSCreateHandle(&ver, &qos->h_))
            {
                return NULL;
            }
 
            if (noaddress)
            {
                if (!QOSAddSocketToFlow(qos->h_, fd, NULL, QOSTrafficTypeControl, QOS_NON_ADAPTIVE_FLOW, &qos->f_))
                {
                    return NULL;
                }
            }
            else
            {
                if (port <= IPEndPoint::MinPort || port > IPEndPoint::MaxPort)
                {
                    return NULL;
                }
 
                if (!host.is_v4() && !host.is_v6())
                {
                    return NULL;
                }
 
                if (IPEndPoint::IsInvalid(host))
                {
                    return NULL;
                }
 
                if (host.is_v4())
                {
                    sockaddr_in in{};
                    in.sin_family = AF_INET;
                    in.sin_port = htons(port);
                    in.sin_addr.s_addr = htonl(host.to_v4().to_uint());
 
                    if (!QOSAddSocketToFlow(qos->h_, fd, reinterpret_cast<sockaddr*>(&in), QOSTrafficTypeControl, QOS_NON_ADAPTIVE_FLOW, &qos->f_))
                    {
                        return NULL;
                    }
                }
                else
                {
                    sockaddr_in6 in6{};
                    in6.sin6_family = AF_INET6;
                    in6.sin6_port = htons(port);
                    memcpy(&in6.sin6_addr, host.to_v6().to_bytes().data(), sizeof(in6.sin6_addr));
 
                    if (!QOSAddSocketToFlow(qos->h_, fd, reinterpret_cast<sockaddr*>(&in6), QOSTrafficTypeControl, QOS_NON_ADAPTIVE_FLOW, &qos->f_))
                    {
                        return NULL;
                    }
                }
            }
 
            // We shift the complete ToS value by 3 to get rid of the 3 bit ECN field
            DWORD dscp = 26;
 
            // Sets DSCP to the same as Linux
            // This will fail if we're not admin, but we ignore it
            if (!QOSSetFlow(qos->h_, qos->f_, QOSSetOutgoingDSCPValue, sizeof(DWORD), &dscp, 0, NULL))
            {
                return NULL;
            }
 
            return qos;
        }

参考文档：

https://learn.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options#windows-support-for-ip_proto-options

https://learn.microsoft.com/en-us/windows-server/networking/technologies/qos/qos-policy-manage#advanced-qos-settings-dscp-marking-override

https://learn.microsoft.com/en-us/windows-server/networking/technologies/qos/qos-policy-manage#advanced-qos-settings-dscp-marking-override

https://learn.microsoft.com/en-us/previous-versions/windows/desktop/dd874008(v=vs.85)