using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace DellRoutes
{
    class Program
    {
        [ComVisible(false), StructLayout(LayoutKind.Sequential)]
        internal struct IPForwardTable
        {
            public uint Size;

            [MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.Struct, SizeParamIndex = 0)]
            public IPFORWARDROW[] Table;
        };

        [ComVisible(false), StructLayout(LayoutKind.Sequential)]
        internal struct IPFORWARDROW
        {
            internal int /*DWORD*/ dwForwardDest;
            internal int /*DWORD*/ dwForwardMask;
            internal int /*DWORD*/ dwForwardPolicy;
            internal int /*DWORD*/ dwForwardNextHop;
            internal int /*DWORD*/ dwForwardIfIndex;
            internal int /*DWORD*/ dwForwardType;
            internal int /*DWORD*/ dwForwardProto;
            internal int /*DWORD*/ dwForwardAge;
            internal int /*DWORD*/ dwForwardNextHopAS;
            internal int /*DWORD*/ dwForwardMetric1;
            internal int /*DWORD*/ dwForwardMetric2;
            internal int /*DWORD*/ dwForwardMetric3;
            internal int /*DWORD*/ dwForwardMetric4;
            internal int /*DWORD*/ dwForwardMetric5;
        };

        [DllImport("iphlpapi", CharSet = CharSet.Auto)]
        private extern static int GetIpForwardTable(IntPtr /*PMIB_IPFORWARDTABLE*/ pIpForwardTable, ref int /*PULONG*/ pdwSize, bool bOrder);

        [DllImport("iphlpapi", CharSet = CharSet.Auto)]
        private extern static int CreateIpForwardEntry(IntPtr /*PMIB_IPFORWARDROW*/ pRoute);

        static void Main(string[] args)
        {
            var fwdTable = IntPtr.Zero;
            int size = 0;
            var result = GetIpForwardTable(fwdTable, ref size, true);
            fwdTable = Marshal.AllocHGlobal(size);

            result = GetIpForwardTable(fwdTable, ref size, true);
            var str = (IPForwardTable) Marshal.PtrToStructure(fwdTable, typeof(IPForwardTable));

            Marshal.FreeHGlobal(fwdTable);
        }
    }
}