DynamicWinsockMethods.cs

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using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.InteropServices;
using System.Threading;
 
namespace System.Net.Sockets;
 
internal sealed class DynamicWinsockMethods
{
    private static readonly List<DynamicWinsockMethods> s_methodTable = new List<DynamicWinsockMethods>();
 
    private readonly AddressFamily _addressFamily;
 
    private readonly SocketType _socketType;
 
    private readonly ProtocolType _protocolType;
 
    private AcceptExDelegate _acceptEx;
 
    private GetAcceptExSockaddrsDelegate _getAcceptExSockaddrs;
 
    private ConnectExDelegate _connectEx;
 
    private TransmitPacketsDelegate _transmitPackets;
 
    private DisconnectExDelegate _disconnectEx;
 
    private WSARecvMsgDelegate _recvMsg;
 
    public static DynamicWinsockMethods GetMethods(AddressFamily addressFamily, SocketType socketType, ProtocolType protocolType)
    {
        lock (s_methodTable)
        {
            DynamicWinsockMethods dynamicWinsockMethods;
            for (int i = 0; i < s_methodTable.Count; i++)
            {
                dynamicWinsockMethods = s_methodTable[i];
                if (dynamicWinsockMethods._addressFamily == addressFamily && dynamicWinsockMethods._socketType == socketType && dynamicWinsockMethods._protocolType == protocolType)
                {
                    return dynamicWinsockMethods;
                }
            }
            dynamicWinsockMethods = new DynamicWinsockMethods(addressFamily, socketType, protocolType);
            s_methodTable.Add(dynamicWinsockMethods);
            return dynamicWinsockMethods;
        }
    }
 
    private DynamicWinsockMethods(AddressFamily addressFamily, SocketType socketType, ProtocolType protocolType)
    {
        _addressFamily = addressFamily;
        _socketType = socketType;
        _protocolType = protocolType;
    }
 
    private unsafe static T CreateDelegate<T>([NotNull] ref T cache, SafeSocketHandle socketHandle, string guidString) where T : Delegate
    {
        Guid guid = new Guid(guidString);
        IntPtr funcPtr = IntPtr.Zero;
        if (global::Interop.Winsock.WSAIoctl(socketHandle, -939524090, ref guid, sizeof(Guid), out funcPtr, sizeof(IntPtr), out var _, IntPtr.Zero, IntPtr.Zero) != 0)
        {
            throw new SocketException();
        }
        Interlocked.CompareExchange(ref cache, Marshal.GetDelegateForFunctionPointer<T>(funcPtr), null);
        return cache;
    }
 
    internal AcceptExDelegate GetAcceptExDelegate(SafeSocketHandle socketHandle)
    {
        return _acceptEx ?? CreateDelegate(ref _acceptEx, socketHandle, "b5367df1cbac11cf95ca00805f48a192");
    }
 
    internal GetAcceptExSockaddrsDelegate GetGetAcceptExSockaddrsDelegate(SafeSocketHandle socketHandle)
    {
        return _getAcceptExSockaddrs ?? CreateDelegate(ref _getAcceptExSockaddrs, socketHandle, "b5367df2cbac11cf95ca00805f48a192");
    }
 
    internal ConnectExDelegate GetConnectExDelegate(SafeSocketHandle socketHandle)
    {
        return _connectEx ?? CreateDelegate(ref _connectEx, socketHandle, "25a207b9ddf346608ee976e58c74063e");
    }
 
    internal DisconnectExDelegate GetDisconnectExDelegate(SafeSocketHandle socketHandle)
    {
        return _disconnectEx ?? CreateDelegate(ref _disconnectEx, socketHandle, "7fda2e118630436fa031f536a6eec157");
    }
 
    internal WSARecvMsgDelegate GetWSARecvMsgDelegate(SafeSocketHandle socketHandle)
    {
        return _recvMsg ?? CreateDelegate(ref _recvMsg, socketHandle, "f689d7c86f1f436b8a53e54fe351c322");
    }
 
    internal TransmitPacketsDelegate GetTransmitPacketsDelegate(SafeSocketHandle socketHandle)
    {
        return _transmitPackets ?? CreateDelegate(ref _transmitPackets, socketHandle, "d9689da01f9011d3997100c04f68c876");
    }
}