SocketProtocolSupportPal.cs

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using System.Net.Sockets;
using System.Runtime.InteropServices;
 
namespace System.Net;
 
internal static class SocketProtocolSupportPal
{
    public static bool OSSupportsIPv6 { get; } = IsSupported(AddressFamily.InterNetworkV6) && !IsIPv6Disabled();
 
 
    public static bool OSSupportsIPv4 { get; } = IsSupported(AddressFamily.InterNetwork);
 
 
    public static bool OSSupportsUnixDomainSockets { get; } = IsSupported(AddressFamily.Unix);
 
 
    private static bool IsIPv6Disabled()
    {
        if (AppContext.TryGetSwitch("System.Net.DisableIPv6", out var isEnabled))
        {
            return isEnabled;
        }
        string environmentVariable = Environment.GetEnvironmentVariable("DOTNET_SYSTEM_NET_DISABLEIPV6");
        if (environmentVariable != null)
        {
            if (!(environmentVariable == "1"))
            {
                return environmentVariable.Equals("true", StringComparison.OrdinalIgnoreCase);
            }
            return true;
        }
        return false;
    }
 
    private static bool IsSupported(AddressFamily af)
    {
        global::Interop.Winsock.EnsureInitialized();
        IntPtr intPtr = (IntPtr)(-1);
        IntPtr intPtr2 = intPtr;
        try
        {
            intPtr2 = global::Interop.Winsock.WSASocketW(af, SocketType.Stream, 0, IntPtr.Zero, 0, 128);
            return intPtr2 != intPtr || Marshal.GetLastWin32Error() != 10047;
        }
        finally
        {
            if (intPtr2 != intPtr)
            {
                global::Interop.Winsock.closesocket(intPtr2);
            }
        }
    }
}