the-cycle/src/Prospect.Unreal/Net/UIpConnection.cs

using System.Net;
using System.Net.Sockets;
using Prospect.Unreal.Core;
using Prospect.Unreal.Exceptions;
using Prospect.Unreal.Net.Packets.Control;

namespace Prospect.Unreal.Net;

public class UIpConnection : UNetConnection
{
    public const int IpHeaderSize = 20;
    public const int UdpHeaderSize = IpHeaderSize + 8;

    /// <summary>
    ///     Cached time of the first send socket error that will be used to compute disconnect delay.
    /// </summary>
    private double _socketErrorSendDelayStartTime;
    
    /// <summary>
    ///     Cached time of the first recv socket error that will be used to compute disconnect delay.
    /// </summary>
    private double _socketErrorRecvDelayStartTime;
    
    public UdpClient? Socket { get; private set; }
    
    public override void InitBase(UNetDriver inDriver, UdpClient inSocket, FUrl inURL, EConnectionState inState, int inMaxPacket = 0, int inPacketOverhead = 0)
    {
        base.InitBase(inDriver, inSocket, inURL, inState, 
            (inMaxPacket == 0 || inMaxPacket > MaxPacketSize) ? MaxPacketSize : inMaxPacket, 
            inPacketOverhead == 0 ? UdpHeaderSize : inPacketOverhead);
        
        Socket = inSocket;
    }

    public override void InitRemoteConnection(UNetDriver inDriver, UdpClient inSocket, FUrl inURL, IPEndPoint inRemoteAddr, EConnectionState inState, int inMaxPacket = 0, int inPacketOverhead = 0)
    {
        InitBase(inDriver, inSocket, inURL, inState, 
            (inMaxPacket == 0 || inMaxPacket > MaxPacketSize) ? MaxPacketSize : inMaxPacket, 
            inPacketOverhead == 0 ? UdpHeaderSize : inPacketOverhead);

        RemoteAddr = inRemoteAddr;
        Url.Host = RemoteAddr.Address;

        // Initialize our send bunch
        InitSendBuffer();

        // This is for a client that needs to log in, setup ClientLoginState and ExpectedClientLoginMsgType to reflect that
        SetClientLoginState(EClientLoginState.LoggingIn);
        SetExpectedClientLoginMsgType(NMT.Hello); // TODO: NMT_HELLO
    }

    public override void InitLocalConnection(UNetDriver inDriver, UdpClient inSocket, FUrl inURL, EConnectionState inState, int inMaxPacket = 0, int inPacketOverhead = 0)
    {
        InitBase(inDriver, inSocket, inURL, inState,
            // Use the default packet size/overhead unless overridden by a child class
            (inMaxPacket == 0 || inMaxPacket > MaxPacketSize) ? MaxPacketSize : inMaxPacket,
            inPacketOverhead == 0 ? inMaxPacket : inPacketOverhead);
        //RemoteAddr = new IPEndPoint(inURL.Host, inURL.Port);
        InitSendBuffer();
    }

    public override void LowLevelSend(byte[] data, int countBits, FOutPacketTraits traits)
    {
        // TODO: Improve according to UE4

        var dataToSend = data;
        
        // Process any packet modifiers
        if (Handler != null && !Handler.GetRawSend())
        {
            var processedData = Handler.Outgoing(data, countBits, traits);
            if (!processedData.Error)
            {
                dataToSend = processedData.Data;
                countBits = processedData.CountBits;
            }
            else
            {
                countBits = 0;
            }
        }

        var countBytes = FMath.DivideAndRoundUp(countBits, 8);
        if (countBits > 0)
        {
            if (Socket == null)
            {
                throw new UnrealNetException();
            }

            // can't send remote addr if client is already set. receive is called before now too, so need to establish socket before then.
            if (RemoteAddr.Address.GetAddressBytes().All(a => a == 0xff))
                Socket.Send(dataToSend, countBytes);

            else
                Socket.Send(dataToSend, countBytes, RemoteAddr);
        }
    }

    public override string LowLevelGetRemoteAddress(bool bAppendPort = false)
    {
        if (RemoteAddr != null)
        {
            // TODO: Remove port
            return RemoteAddr.ToString();
        }

        return string.Empty;
    }

    public override string LowLevelDescribe()
    {
        throw new NotImplementedException();
    }

    public override void CleanUp()
    {
        throw new NotImplementedException();
    }

    public override void ReceivedRawPacket(FReceivedPacketView packetView)
    {
        _socketErrorRecvDelayStartTime = 0;
        
        base.ReceivedRawPacket(packetView);
    }

    public override float GetTimeoutValue()
    {
        throw new NotImplementedException();
    }
}