在Windows CE 6.0的C＃中收集本地网络信息的问题

Question

I'm doing some cross platform development and am having issues trying to gather local network information using C# on Windows CE 6.0. I'm gathering information such as local IP address and gateway IP address. My method to get the local IP address works fine on all platforms but the method to get the gateway IP address doesn't work on CE 6.0, below is what I have

    private IPAddress GetGatewayInfo()       
    {
        //Console.WriteLine("Gateways");
        NetworkInterface[] adapters = NetworkInterface.GetAllNetworkInterfaces();
        foreach (NetworkInterface adapter in adapters)
        {
            IPInterfaceProperties adapterProperties = adapter.GetIPProperties();
            GatewayIPAddressInformationCollection addresses = adapterProperties.GatewayAddresses;
            if (addresses.Count > 0)
            {
                foreach (GatewayIPAddressInformation address in addresses)
                {
                    Console.WriteLine("Gateway IP is : {0}", address.Address);
                    return address.Address;

                }

            }

        }
        return null;
    }

So after some research I found methods like GetAllNetworkInterfaces() aren't supported on CE and I found another way to get this information which is listed below

class libGetAdaptersInfo
{
    [DllImport("iphlpapi.dll")]
    private static extern int GetAdaptersInfo(IntPtr pAdapterInfo, ref Int64 pBufOutLen);

    private const int MAX_ADAPTER_DESCRIPTION_LENGTH = 128;
    private const int ERROR_BUFFER_OVERFLOW = 111;
    private const int MAX_ADAPTER_NAME_LENGTH = 256;
    private const int MAX_ADAPTER_ADDRESS_LENGTH = 8;
    private const int MIB_IF_TYPE_OTHER = 1;
    private const int MIB_IF_TYPE_ETHERNET = 6;
    private const int MIB_IF_TYPE_TOKENRING = 9;
    private const int MIB_IF_TYPE_FDDI = 15;
    private const int MIB_IF_TYPE_PPP = 23;
    private const int MIB_IF_TYPE_LOOPBACK = 24;
    private const int MIB_IF_TYPE_SLIP = 28;

    [StructLayout(LayoutKind.Sequential)]
    private struct IP_ADDRESS_STRING
    {
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)]
        public string Address;
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct IP_ADDR_STRING
    {
        public IntPtr Next;
        public IP_ADDRESS_STRING IpAddress;
        public IP_ADDRESS_STRING IpMask;
        public Int32 Context;
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct IP_ADAPTER_INFO
    {
        public IntPtr Next;
        public Int32 ComboIndex;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = MAX_ADAPTER_NAME_LENGTH + 4)]
        public string AdapterName;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = MAX_ADAPTER_DESCRIPTION_LENGTH + 4)]
        public string AdapterDescription;
        public UInt32 AddressLength;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = MAX_ADAPTER_ADDRESS_LENGTH)]
        public byte[] Address;
        public Int32 Index;
        public UInt32 Type;
        public UInt32 DhcpEnabled;
        public IntPtr CurrentIpAddress;
        public IP_ADDR_STRING IpAddressList;
        public IP_ADDR_STRING GatewayList;
        public IP_ADDR_STRING DhcpServer;
        public bool HaveWins;
        public IP_ADDR_STRING PrimaryWinsServer;
        public IP_ADDR_STRING SecondaryWinsServer;
        public Int32 LeaseObtained;
        public Int32 LeaseExpires;
    }

    public static void GetAdapters()
    {
        long structSize = Marshal.SizeOf(typeof(IP_ADAPTER_INFO));
        IntPtr pArray = Marshal.AllocHGlobal((int)new IntPtr(structSize));

        int ret = GetAdaptersInfo(pArray, ref structSize);

        if (ret == ERROR_BUFFER_OVERFLOW) // ERROR_BUFFER_OVERFLOW == 111
        {
            // Buffer was too small, reallocate the correct size for the buffer.
            pArray = Marshal.ReAllocHGlobal(pArray, new IntPtr(structSize));

            ret = GetAdaptersInfo(pArray, ref structSize);
        } // if

        if (ret == 0)
        {
            // Call Succeeded
            IntPtr pEntry = pArray;

            do
            {
                // Retrieve the adapter info from the memory address
                IP_ADAPTER_INFO entry = (IP_ADAPTER_INFO)Marshal.PtrToStructure(pEntry, typeof(IP_ADAPTER_INFO));


                Console.WriteLine("\n");
                Console.WriteLine("Index: {0}", entry.Index.ToString());

                // Adapter Type
                string tmpString = string.Empty;
                switch (entry.Type)
                {
                    case MIB_IF_TYPE_ETHERNET: tmpString = "Ethernet"; break;
                    case MIB_IF_TYPE_TOKENRING: tmpString = "Token Ring"; break;
                    case MIB_IF_TYPE_FDDI: tmpString = "FDDI"; break;
                    case MIB_IF_TYPE_PPP: tmpString = "PPP"; break;
                    case MIB_IF_TYPE_LOOPBACK: tmpString = "Loopback"; break;
                    case MIB_IF_TYPE_SLIP: tmpString = "Slip"; break;
                    default: tmpString = "Other/Unknown"; break;
                } // switch
                Console.WriteLine("Adapter Type: {0}", tmpString);

                Console.WriteLine("Name: {0}", entry.AdapterName);
                Console.WriteLine("Desc: {0}\n", entry.AdapterDescription);

                Console.WriteLine("DHCP Enabled: {0}", (entry.DhcpEnabled == 1) ? "Yes" : "No");

                if (entry.DhcpEnabled == 1)
                {
                    Console.WriteLine("DHCP Server : {0}", entry.DhcpServer.IpAddress.Address);

                    // Lease Obtained (convert from "time_t" to C# DateTime)
                    DateTime pdatDate = new DateTime(1970, 1, 1).AddSeconds(entry.LeaseObtained).ToLocalTime();
                    Console.WriteLine("Lease Obtained: {0}", pdatDate.ToString());

                    // Lease Expires (convert from "time_t" to C# DateTime)
                    pdatDate = new DateTime(1970, 1, 1).AddSeconds(entry.LeaseExpires).ToLocalTime();
                    Console.WriteLine("Lease Expires : {0}\n", pdatDate.ToString());
                } // if DhcpEnabled

                Console.WriteLine("IP Address     : {0}", entry.IpAddressList.IpAddress.Address);
                Console.WriteLine("Subnet Mask    : {0}", entry.IpAddressList.IpMask.Address);
                Console.WriteLine("Default Gateway: {0}", entry.GatewayList.IpAddress.Address);

                // MAC Address (data is in a byte[])
                tmpString = string.Empty;
                for (int i = 0; i < entry.AddressLength - 1; i++)
                {
                    tmpString += string.Format("{0:X2}-", entry.Address[i]);
                }
                Console.WriteLine("MAC Address    : {0}{1:X2}\n", tmpString, entry.Address[entry.AddressLength - 1]);

                Console.WriteLine("Has WINS: {0}", entry.HaveWins ? "Yes" : "No");
                if (entry.HaveWins)
                {
                    Console.WriteLine("Primary WINS Server  : {0}", entry.PrimaryWinsServer.IpAddress.Address);
                    Console.WriteLine("Secondary WINS Server: {0}", entry.SecondaryWinsServer.IpAddress.Address);
                } // HaveWins

                // Get next adapter (if any)
                pEntry = entry.Next;

            }
            while (pEntry != IntPtr.Zero);

            Marshal.FreeHGlobal(pArray);

        } // if
        else
        {
            Marshal.FreeHGlobal(pArray);
            throw new InvalidOperationException("GetAdaptersInfo failed: " + ret);
        }

    } // GetAdapters

The above method worked fine on Windows 7 and printed all correct values but when I tested it on CE I still had issues, such as all values saying they are unknown/empty, an index out of range exception when trying to get the MAC address information, and crashing at the end of the program with an "Not supported exception". I'm pretty stumped now as it works perfectly fine on win 7 so I'm not sure what to try next as this was the only method I could find that was supposed to work on CE, does anyone know how I could fix these issues or know of another method to get the gateway IP address? thanks

Answer 1

GetAdaptersInfo should work, but I see a few issues with the P/Invoke definitions:

• On Windows CE, the second parameter to GetAdaptersInfo is a pointer to a 32-bit integer, not 64-bit
• Strings in iphlpapi context are C-style char arrays, so the CE default of 2-byte Unicode selected with UnmanagedType.ByValTStr won't work. Specify CharSet = CharSet.Ansi in the StructLayout attribute on all structs that contain strings
• HaveWins is specified as a .NET bool , but if I remember correctly this is marshalled as a single byte. Stick a [MarshalAs(UnmanagedType.Bool)] in front, or change to int to map correctly to the underlying type.

I may have missed something, so do check your code thoroughly against the CE definitions. A good place to start might be https://msdn.microsoft.com/en-us/library/ms891170.aspx (CE 5.0 documentation, but same as 6.0).