TeredoHelper.cs

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using System.ComponentModel;
using System.Net.Sockets;
using System.Runtime.InteropServices;
using System.Threading;
 
namespace System.Net.NetworkInformation;
 
internal sealed class TeredoHelper
{
    private readonly Action<object> _callback;
 
    private readonly object _state;
 
    private bool _runCallbackCalled;
 
    private GCHandle _gcHandle;
 
    private SafeCancelMibChangeNotify _cancelHandle;
 
    private TeredoHelper(Action<object> callback, object state)
    {
        _callback = callback;
        _state = state;
        _gcHandle = GCHandle.Alloc(this);
    }
 
    public unsafe static bool UnsafeNotifyStableUnicastIpAddressTable(Action<object> callback, object state)
    {
        TeredoHelper teredoHelper = new TeredoHelper(callback, state);
        try
        {
            SafeFreeMibTable table;
            uint num = global::Interop.IpHlpApi.NotifyStableUnicastIpAddressTable(AddressFamily.Unspecified, out table, (delegate* unmanaged<IntPtr, IntPtr, void>)(delegate*<IntPtr, IntPtr, void>)(&OnStabilized), GCHandle.ToIntPtr(teredoHelper._gcHandle), out teredoHelper._cancelHandle);
            table.Dispose();
            switch (num)
            {
            case 997u:
                teredoHelper = null;
                return false;
            default:
                throw new Win32Exception((int)num);
            case 0u:
                return true;
            }
        }
        finally
        {
            teredoHelper?.Dispose();
        }
    }
 
    private void Dispose()
    {
        _cancelHandle?.Dispose();
        if (_gcHandle.IsAllocated)
        {
            _gcHandle.Free();
        }
    }
 
    [UnmanagedCallersOnly]
    private static void OnStabilized(IntPtr context, IntPtr table)
    {
        global::Interop.IpHlpApi.FreeMibTable(table);
        TeredoHelper teredoHelper = (TeredoHelper)GCHandle.FromIntPtr(context).Target;
        if (teredoHelper._runCallbackCalled)
        {
            return;
        }
        lock (teredoHelper)
        {
            if (!teredoHelper._runCallbackCalled)
            {
                teredoHelper._runCallbackCalled = true;
                ThreadPool.QueueUserWorkItem(delegate(object o)
                {
                    TeredoHelper teredoHelper2 = (TeredoHelper)o;
                    teredoHelper2.Dispose();
                    teredoHelper2._callback(teredoHelper2._state);
                }, teredoHelper);
            }
        }
    }
}