FeatherMC/src/network/TCPListener.cpp

#include "../Common.h"

#include "Protocol.h"
#include "TCPListener.h"
#include "NetworkManager.h"
#include "NetworkMessage.h"
#include "PacketReader.h"
#include "ClientHandle.h"

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

#include <mutex>
#include <cstring>

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 final : public ClientHandle
    {
    private:
        friend class TCPListener;

        // Protocol for this specific client
        Protocol m_protocol;

        TCPListener *m_parent;
        bufferevent *m_bufferEvent;

        std::vector<uint8_t> m_incomingData;
        std::mutex m_mutex;
    public:
        TCPListenerClient(TCPListener* parent, evutil_socket_t socket)
            : m_parent(parent)
            , m_protocol(this)
            , 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))
        {
            printf("Created TCPListenerClient\n");
            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()
        {
            printf("Read callback!\n");
            auto lock = std::unique_lock(m_mutex);
            
            uint8_t data[1KB];
            size_t length;

            size_t originalSize = m_incomingData.size();

            // TODO: could switch to bufferevent_read_buffer and use evbuffer to avoid copies
            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);
            }

            uint8_t* dataPtr = &(m_incomingData.data()[originalSize]);
            PacketReader reader(dataPtr);

            m_protocol.HandlePacket(reader);
        }

        template <typename T>
        void WritePingMessage(T& message, std::string json)
        {
            // Packet ID
            message.WriteVarInt(0);
            // JSON Contents
            message.WriteString(json.c_str(), static_cast<int32_t>(json.length()));
        }
        DEFINE_MESSAGE_WRAPPER(WritePingMessage);

        bool SendShitTest()
        {
            auto lock = std::unique_lock(m_mutex);
            const std::string 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 = WritePingMessage(json_template);

            bufferevent_write(m_bufferEvent, message.GetData(), message.GetDataSize());
            return true;
        }

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

            //SendShitTest();
        }

        void EventCallback(short event)
        {
            printf("Event! %d\n", event);
        }
    };

    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()
    {

    }

    void TCPListener::DispatchQueuedPackets()
    {
        for (const auto& client : m_clients)
        {
            while (!client->m_queue.empty())
            {
                NetworkMessage *msg = client->m_queue.front();
                printf("Writing packet of size %u\n", msg->GetDataSize());
                bufferevent_write(client->m_bufferEvent, msg->GetData(), msg->GetDataSize());
                client->m_queue.pop();
            }
        }
    }
}