SystemIPv4InterfaceProperties.cs

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using System.Runtime.InteropServices;
 
namespace System.Net.NetworkInformation;
 
internal sealed class SystemIPv4InterfaceProperties : IPv4InterfaceProperties
{
    private readonly bool _haveWins;
 
    private readonly bool _dhcpEnabled;
 
    private readonly bool _routingEnabled;
 
    private readonly uint _index;
 
    private readonly uint _mtu;
 
    private bool _autoConfigEnabled;
 
    private bool _autoConfigActive;
 
    public override bool UsesWins => _haveWins;
 
    public override bool IsDhcpEnabled => _dhcpEnabled;
 
    public override bool IsForwardingEnabled => _routingEnabled;
 
    public override bool IsAutomaticPrivateAddressingEnabled => _autoConfigEnabled;
 
    public override bool IsAutomaticPrivateAddressingActive => _autoConfigActive;
 
    public override int Mtu => (int)_mtu;
 
    public override int Index => (int)_index;
 
    internal SystemIPv4InterfaceProperties(global::Interop.IpHlpApi.FIXED_INFO fixedInfo, global::Interop.IpHlpApi.IpAdapterAddresses ipAdapterAddresses)
    {
        _index = ipAdapterAddresses.index;
        _routingEnabled = fixedInfo.enableRouting;
        _dhcpEnabled = (ipAdapterAddresses.flags & global::Interop.IpHlpApi.AdapterFlags.DhcpEnabled) != 0;
        _haveWins = ipAdapterAddresses.firstWinsServerAddress != IntPtr.Zero;
        _mtu = ipAdapterAddresses.mtu;
        GetPerAdapterInfo(ipAdapterAddresses.index);
    }
 
    private void GetPerAdapterInfo(uint index)
    {
        if (index == 0)
        {
            return;
        }
        uint pOutBufLen = 0u;
        uint perAdapterInfo = global::Interop.IpHlpApi.GetPerAdapterInfo(index, IntPtr.Zero, ref pOutBufLen);
        while (true)
        {
            switch (perAdapterInfo)
            {
            case 111u:
            {
                IntPtr intPtr = Marshal.AllocHGlobal((int)pOutBufLen);
                try
                {
                    perAdapterInfo = global::Interop.IpHlpApi.GetPerAdapterInfo(index, intPtr, ref pOutBufLen);
                    if (perAdapterInfo == 0)
                    {
                        global::Interop.IpHlpApi.IpPerAdapterInfo ipPerAdapterInfo = Marshal.PtrToStructure<global::Interop.IpHlpApi.IpPerAdapterInfo>(intPtr);
                        _autoConfigEnabled = ipPerAdapterInfo.autoconfigEnabled;
                        _autoConfigActive = ipPerAdapterInfo.autoconfigActive;
                    }
                }
                finally
                {
                    Marshal.FreeHGlobal(intPtr);
                }
                break;
            }
            default:
                throw new NetworkInformationException((int)perAdapterInfo);
            case 0u:
                return;
            }
        }
    }
}