FeatherMC/src/network/TCPListener.cpp

#include "TCPListener.h"
#include "NetworkManager.h"

#include <event2/event.h>
#include <event2/listener.h>
#include <event2/buffer.h>
#include <event2/bufferevent.h>

#include <mutex>
#include <cstring>

#include "Buffer.h"

namespace Feather::Network
{
    class TCPSocket
    {
    public:
        TCPSocket()
        {
            m_socket = socket(AF_INET6, SOCK_STREAM, IPPROTO_TCP);

            // Can't create IPv6 socket? Create an IPv4 one.
            if (!(m_ipv6 = IsValid()))
                m_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
        }

        ~TCPSocket()
        {
            Close();
        }

        bool IsIPV6() const { return m_ipv6; }

        bool MarkReusable()
        {
            return evutil_make_listen_socket_reuseable(m_socket) == 0;
        }

        bool MarkDualBind()
        {
            constexpr uint32_t zero = 0;
            return setsockopt(m_socket, IPPROTO_IPV6, IPV6_V6ONLY,
                reinterpret_cast<const char*>(&zero),
                sizeof(zero)) == 0;
        }

        bool Bind(uint16_t port)
        {
            sockaddr_in6 name_ipv6 = {};
            name_ipv6.sin6_family = AF_INET6;
            name_ipv6.sin6_port = ntohs(port);

            sockaddr_in name_ipv4 = {};
            name_ipv4.sin_family = AF_INET;
            name_ipv4.sin_port = ntohs(port);

            return m_ipv6
                ? BindGeneric(name_ipv6)
                : BindGeneric(name_ipv4);
        }

        bool MarkNonBlocking()
        {
            return evutil_make_socket_nonblocking(m_socket) == 0;
        }

        bool Close()
        {
            if (!IsValid())
                return true;

            return evutil_closesocket(m_socket) == 0;
        }

        template <typename T>
        evconnlistener* Listen(evconnlistener_cb callback, T* self)
        {
            if (listen(m_socket, SOMAXCONN) != 0)
                return nullptr;

            return evconnlistener_new(
                NetworkManager::Instance().GetEventBase(),
                callback, reinterpret_cast<void*>(self),
                LEV_OPT_CLOSE_ON_FREE | LEV_OPT_REUSEABLE,
                0,
                m_socket);
        }

        bool IsValid() const { return m_socket != EVUTIL_INVALID_SOCKET; }

    private:

        template <typename T>
        bool BindGeneric(const T& name)
        {
            return bind(m_socket, reinterpret_cast<const sockaddr*>(&name), sizeof(name)) == 0;
        }

        evutil_socket_t m_socket;
        bool            m_ipv6;
    };

    class TCPListenerClient
    {
    public:
        TCPListenerClient(TCPListener* parent, evutil_socket_t socket)
            : m_parent(parent)
            , m_bufferEvent(bufferevent_socket_new(NetworkManager::Instance().GetEventBase(), socket, BEV_OPT_CLOSE_ON_FREE | BEV_OPT_THREADSAFE | BEV_OPT_DEFER_CALLBACKS | BEV_OPT_UNLOCK_CALLBACKS))
        {
            bufferevent_setcb(m_bufferEvent,
                [](bufferevent* be, void* self)              { static_cast<TCPListenerClient*>(self)->ReadCallback(); },
                [](bufferevent* be, void* self)              { static_cast<TCPListenerClient*>(self)->WriteCallback(); },
                [](bufferevent* be, short event, void* self) { static_cast<TCPListenerClient*>(self)->EventCallback(event); },
                this);
            bufferevent_enable(m_bufferEvent, EV_READ | EV_WRITE);
        }

        ~TCPListenerClient()
        {
            bufferevent_free(m_bufferEvent);
        }

        void ReadCallback()
        {
            auto lock = std::unique_lock(m_mutex);

            char data[1024];
            size_t length;
            while ((length = bufferevent_read(m_bufferEvent, data, sizeof(data))) > 0)
            {
                size_t oldSize = m_incomingData.size();
                m_incomingData.resize(oldSize + length);
                std::memcpy(&m_incomingData[oldSize], data, length);
            }
        }

        void writeVarInt(int value, std::vector<unsigned char>& msg) {
            do {
                byte temp = (byte)(value & 0b01111111);
                // Note: >>> means that the sign bit is shifted with the rest of the number rather than being left alone
                value >>= 7;
                if (value != 0) {
                    temp |= 0b10000000;
                }
                msg.push_back(temp);
            } while (value != 0);
        }

        int fuckvarintsize(int value)
        {
            int i = 0;
            do {
                byte temp = (byte)(value & 0b01111111);
                // Note: >>> means that the sign bit is shifted with the rest of the number rather than being left alone
                value >>= 7;
                if (value != 0) {
                    temp |= 0b10000000;
                }
                i++;
            } while (value != 0);

            return i;
        }

        std::vector<unsigned char> EncodeMessageTest(int packetid, const unsigned char* data, size_t size)
        {
            Buffer msg;

            // TODO: message size prepender. could potentially be done without copying 
            int msg_size     = fuckvarintsize(packetid) + fuckvarintsize(int(size)) + int(size);
            msg.WriteVarInt(msg_size);
            
            msg.WriteVarInt(packetid);
            msg.WriteVarInt(size);
            for (size_t i = 0; i < size; i++)
                msg.WriteByte(data[i]);

            return msg.GetData();
        }

        bool SendShitTest()
        {
            auto lock = std::unique_lock(m_mutex);
            const char json_template[] = 
R"({
    "version": {
        "name": "1.16.1",
        "protocol": 736
    },
    "players": {
        "max": 10,
        "online": 10,
        "sample": [
            {
                "name": "thinkofdeath",
                "id": "4566e69f-c907-48ee-8d71-d7ba5aa00d20"
            }
        ]
    },	
    "description": {
        "text": "Hello Nukem!"
    }
})";

            auto message = EncodeMessageTest(0, (const unsigned char*)json_template, sizeof(json_template));

            bufferevent_write(m_bufferEvent, message.data(), message.size());
            return true;
        }

        void WriteCallback()
        {
            printf("Write callback!\n");
            SendShitTest();
        }

        void EventCallback(short event)
        {
            printf("Event!\n");
        }
    private:
        TCPListener* m_parent;
        bufferevent* m_bufferEvent;

        std::vector<char> m_incomingData;
        std::mutex m_mutex;
    };

    TCPListener::TCPListener(uint16_t port)
    {
        // Setup the listen socket.
        auto socket = std::make_unique<TCPSocket>();

        if (!socket->IsValid())
            return;

        if (!socket->MarkReusable())
            return;

        if (socket->IsIPV6() && !socket->MarkDualBind())
            return;

        if (!socket->Bind(port))
            return;

        if (!socket->MarkNonBlocking())
            return;

        auto ListenerCallback = [](evconnlistener* evListener, evutil_socket_t socket, sockaddr* addr, int len, void* self)
        {
            TCPListener* listener = static_cast<TCPListener*>(self);
            listener->m_clients.emplace_back(std::make_unique<TCPListenerClient>(listener, socket));
        };

        if (!socket->Listen(ListenerCallback, this))
            return;

        m_socket = std::move(socket);
    }

    TCPListener::~TCPListener()
    {

    }
}