IPIntertop - Win32 `GetAdaptersAddresses()` for C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace WifiLinkSpeed
{
    // Originally from http://www.pinvoke.net/default.aspx/iphlpapi/GetAdaptersAddresses.html
    //  - Extra struct properties that we intoduced with Vista were added
    //  - Tad bit of code clean up
    // By Jaxrtech

    public class IPIntertop
    {
        public enum FAMILY : uint
        {
            /// <summary>
            /// IPv4
            /// </summary>
            AF_INET = 2,
            /// <summary>
            /// IPv6
            /// </summary>
            AF_INET6 = 23,
            /// <summary>
            /// Unpecified. Includes both IPv4 and IPv4
            /// </summary>
            AF_UNSPEC = 0
        }
        public enum FLAGS : uint
        {
            GAA_FLAG_SKIP_UNICAST = 0x0001,
            GAA_FLAG_SKIP_ANYCAST = 0x0002,
            GAA_FLAG_SKIP_MULTICAST = 0x0004,
            GAA_FLAG_SKIP_DNS_SERVER = 0x0008,
            GAA_FLAG_INCLUDE_PREFIX = 0x0010,
            GAA_FLAG_SKIP_FRIENDLY_NAME = 0x0020
        }
        public enum ERROR : uint
        {
            ERROR_SUCCESS = 0,
            ERROR_NO_DATA = 232,
            ERROR_BUFFER_OVERFLOW = 111,
            ERROR_INVALID_PARAMETER = 87
        }
        public enum IF_OPER_STATUS : uint
        {
            IfOperStatusUp = 1,
            IfOperStatusDown,
            IfOperStatusTesting,
            IfOperStatusUnknown,
            IfOperStatusDormant,
            IfOperStatusNotPresent,
            IfOperStatusLowerLayerDown,
        }
        public enum IF_TYPE : uint
        {
            IF_TYPE_OTHER = 1,   // None of the below
            IF_TYPE_REGULAR_1822 = 2,
            IF_TYPE_HDH_1822 = 3,
            IF_TYPE_DDN_X25 = 4,
            IF_TYPE_RFC877_X25 = 5,
            IF_TYPE_ETHERNET_CSMACD = 6,
            IF_TYPE_IS088023_CSMACD = 7,
            IF_TYPE_ISO88024_TOKENBUS = 8,
            IF_TYPE_ISO88025_TOKENRING = 9,
            IF_TYPE_ISO88026_MAN = 10,
            IF_TYPE_STARLAN = 11,
            IF_TYPE_PROTEON_10MBIT = 12,
            IF_TYPE_PROTEON_80MBIT = 13,
            IF_TYPE_HYPERCHANNEL = 14,
            IF_TYPE_FDDI = 15,
            IF_TYPE_LAP_B = 16,
            IF_TYPE_SDLC = 17,
            IF_TYPE_DS1 = 18,  // DS1-MIB
            IF_TYPE_E1 = 19,  // Obsolete; see DS1-MIB
            IF_TYPE_BASIC_ISDN = 20,
            IF_TYPE_PRIMARY_ISDN = 21,
            IF_TYPE_PROP_POINT2POINT_SERIAL = 22,  // proprietary serial
            IF_TYPE_PPP = 23,
            IF_TYPE_SOFTWARE_LOOPBACK = 24,
            IF_TYPE_EON = 25,  // CLNP over IP
            IF_TYPE_ETHERNET_3MBIT = 26,
            IF_TYPE_NSIP = 27,  // XNS over IP
            IF_TYPE_SLIP = 28,  // Generic Slip
            IF_TYPE_ULTRA = 29,  // ULTRA Technologies
            IF_TYPE_DS3 = 30,  // DS3-MIB
            IF_TYPE_SIP = 31,  // SMDS, coffee
            IF_TYPE_FRAMERELAY = 32,  // DTE only
            IF_TYPE_RS232 = 33,
            IF_TYPE_PARA = 34,  // Parallel port
            IF_TYPE_ARCNET = 35,
            IF_TYPE_ARCNET_PLUS = 36,
            IF_TYPE_ATM = 37,  // ATM cells
            IF_TYPE_MIO_X25 = 38,
            IF_TYPE_SONET = 39,  // SONET or SDH
            IF_TYPE_X25_PLE = 40,
            IF_TYPE_ISO88022_LLC = 41,
            IF_TYPE_LOCALTALK = 42,
            IF_TYPE_SMDS_DXI = 43,
            IF_TYPE_FRAMERELAY_SERVICE = 44,  // FRNETSERV-MIB
            IF_TYPE_V35 = 45,
            IF_TYPE_HSSI = 46,
            IF_TYPE_HIPPI = 47,
            IF_TYPE_MODEM = 48,  // Generic Modem
            IF_TYPE_AAL5 = 49,  // AAL5 over ATM
            IF_TYPE_SONET_PATH = 50,
            IF_TYPE_SONET_VT = 51,
            IF_TYPE_SMDS_ICIP = 52,  // SMDS InterCarrier Interface
            IF_TYPE_PROP_VIRTUAL = 53,  // Proprietary virtual/internal
            IF_TYPE_PROP_MULTIPLEXOR = 54,  // Proprietary multiplexing
            IF_TYPE_IEEE80212 = 55,  // 100BaseVG
            IF_TYPE_FIBRECHANNEL = 56,
            IF_TYPE_HIPPIINTERFACE = 57,
            IF_TYPE_FRAMERELAY_INTERCONNECT = 58,  // Obsolete, use 32 or 44
            IF_TYPE_AFLANE_8023 = 59,  // ATM Emulated LAN for 802.3
            IF_TYPE_AFLANE_8025 = 60,  // ATM Emulated LAN for 802.5
            IF_TYPE_CCTEMUL = 61,  // ATM Emulated circuit
            IF_TYPE_FASTETHER = 62,  // Fast Ethernet (100BaseT)
            IF_TYPE_ISDN = 63,  // ISDN and X.25
            IF_TYPE_V11 = 64,  // CCITT V.11/X.21
            IF_TYPE_V36 = 65,  // CCITT V.36
            IF_TYPE_G703_64K = 66,  // CCITT G703 at 64Kbps
            IF_TYPE_G703_2MB = 67,  // Obsolete; see DS1-MIB
            IF_TYPE_QLLC = 68,  // SNA QLLC
            IF_TYPE_FASTETHER_FX = 69,  // Fast Ethernet (100BaseFX)
            IF_TYPE_CHANNEL = 70,
            IF_TYPE_IEEE80211 = 71,  // Radio spread spectrum
            IF_TYPE_IBM370PARCHAN = 72,  // IBM System 360/370 OEMI Channel
            IF_TYPE_ESCON = 73,  // IBM Enterprise Systems Connection
            IF_TYPE_DLSW = 74,  // Data Link Switching
            IF_TYPE_ISDN_S = 75,  // ISDN S/T interface
            IF_TYPE_ISDN_U = 76,  // ISDN U interface
            IF_TYPE_LAP_D = 77,  // Link Access Protocol D
            IF_TYPE_IPSWITCH = 78,  // IP Switching Objects
            IF_TYPE_RSRB = 79,  // Remote Source Route Bridging
            IF_TYPE_ATM_LOGICAL = 80,  // ATM Logical Port
            IF_TYPE_DS0 = 81,  // Digital Signal Level 0
            IF_TYPE_DS0_BUNDLE = 82,  // Group of ds0s on the same ds1
            IF_TYPE_BSC = 83,  // Bisynchronous Protocol
            IF_TYPE_ASYNC = 84,  // Asynchronous Protocol
            IF_TYPE_CNR = 85,  // Combat Net Radio
            IF_TYPE_ISO88025R_DTR = 86,  // ISO 802.5r DTR
            IF_TYPE_EPLRS = 87,  // Ext Pos Loc Report Sys
            IF_TYPE_ARAP = 88,  // Appletalk Remote Access Protocol
            IF_TYPE_PROP_CNLS = 89,  // Proprietary Connectionless Proto
            IF_TYPE_HOSTPAD = 90,  // CCITT-ITU X.29 PAD Protocol
            IF_TYPE_TERMPAD = 91,  // CCITT-ITU X.3 PAD Facility
            IF_TYPE_FRAMERELAY_MPI = 92,  // Multiproto Interconnect over FR
            IF_TYPE_X213 = 93,  // CCITT-ITU X213
            IF_TYPE_ADSL = 94,  // Asymmetric Digital Subscrbr Loop
            IF_TYPE_RADSL = 95,  // Rate-Adapt Digital Subscrbr Loop
            IF_TYPE_SDSL = 96,  // Symmetric Digital Subscriber Loop
            IF_TYPE_VDSL = 97,  // Very H-Speed Digital Subscrb Loop
            IF_TYPE_ISO88025_CRFPRINT = 98,  // ISO 802.5 CRFP
            IF_TYPE_MYRINET = 99,  // Myricom Myrinet
            IF_TYPE_VOICE_EM = 100,  // Voice recEive and transMit
            IF_TYPE_VOICE_FXO = 101,  // Voice Foreign Exchange Office
            IF_TYPE_VOICE_FXS = 102,  // Voice Foreign Exchange Station
            IF_TYPE_VOICE_ENCAP = 103,  // Voice encapsulation
            IF_TYPE_VOICE_OVERIP = 104,  // Voice over IP encapsulation
            IF_TYPE_ATM_DXI = 105,  // ATM DXI
            IF_TYPE_ATM_FUNI = 106,  // ATM FUNI
            IF_TYPE_ATM_IMA = 107,  // ATM IMA
            IF_TYPE_PPPMULTILINKBUNDLE = 108,  // PPP Multilink Bundle
            IF_TYPE_IPOVER_CDLC = 109,  // IBM ipOverCdlc
            IF_TYPE_IPOVER_CLAW = 110,  // IBM Common Link Access to Workstn
            IF_TYPE_STACKTOSTACK = 111,  // IBM stackToStack
            IF_TYPE_VIRTUALIPADDRESS = 112,  // IBM VIPA
            IF_TYPE_MPC = 113,  // IBM multi-proto channel support
            IF_TYPE_IPOVER_ATM = 114,  // IBM ipOverAtm
            IF_TYPE_ISO88025_FIBER = 115,  // ISO 802.5j Fiber Token Ring
            IF_TYPE_TDLC = 116,  // IBM twinaxial data link control
            IF_TYPE_GIGABITETHERNET = 117,
            IF_TYPE_HDLC = 118,
            IF_TYPE_LAP_F = 119,
            IF_TYPE_V37 = 120,
            IF_TYPE_X25_MLP = 121,  // Multi-Link Protocol
            IF_TYPE_X25_HUNTGROUP = 122,  // X.25 Hunt Group
            IF_TYPE_TRANSPHDLC = 123,
            IF_TYPE_INTERLEAVE = 124,  // Interleave channel
            IF_TYPE_FAST = 125,  // Fast channel
            IF_TYPE_IP = 126,  // IP (for APPN HPR in IP networks)
            IF_TYPE_DOCSCABLE_MACLAYER = 127,  // CATV Mac Layer
            IF_TYPE_DOCSCABLE_DOWNSTREAM = 128,  // CATV Downstream interface
            IF_TYPE_DOCSCABLE_UPSTREAM = 129,  // CATV Upstream interface
            IF_TYPE_A12MPPSWITCH = 130,  // Avalon Parallel Processor
            IF_TYPE_TUNNEL = 131,  // Encapsulation interface
            IF_TYPE_COFFEE = 132,  // Coffee pot
            IF_TYPE_CES = 133,  // Circuit Emulation Service
            IF_TYPE_ATM_SUBINTERFACE = 134,  // ATM Sub Interface
            IF_TYPE_L2_VLAN = 135,  // Layer 2 Virtual LAN using 802.1Q
            IF_TYPE_L3_IPVLAN = 136,  // Layer 3 Virtual LAN using IP
            IF_TYPE_L3_IPXVLAN = 137,  // Layer 3 Virtual LAN using IPX
            IF_TYPE_DIGITALPOWERLINE = 138,  // IP over Power Lines
            IF_TYPE_MEDIAMAILOVERIP = 139,  // Multimedia Mail over IP
            IF_TYPE_DTM = 140,  // Dynamic syncronous Transfer Mode
            IF_TYPE_DCN = 141,  // Data Communications Network
            IF_TYPE_IPFORWARD = 142,  // IP Forwarding Interface
            IF_TYPE_MSDSL = 143,  // Multi-rate Symmetric DSL
            IF_TYPE_IEEE1394 = 144,  // IEEE1394 High Perf Serial Bus
            IF_TYPE_RECEIVE_ONLY = 145 // TV adapter type
        }
        public enum IP_SUFFIX_ORIGIN : uint
        {
            /// IpSuffixOriginOther -> 0
            IpSuffixOriginOther = 0,
            IpSuffixOriginManual,
            IpSuffixOriginWellKnown,
            IpSuffixOriginDhcp,
            IpSuffixOriginLinkLayerAddress,
            IpSuffixOriginRandom,
        }
        public enum IP_PREFIX_ORIGIN : uint
        {
            /// IpPrefixOriginOther -> 0
            IpPrefixOriginOther = 0,
            IpPrefixOriginManual,
            IpPrefixOriginWellKnown,
            IpPrefixOriginDhcp,
            IpPrefixOriginRouterAdvertisement,
        }
        public enum IP_DAD_STATE : uint
        {
            /// IpDadStateInvalid -> 0
            IpDadStateInvalid = 0,
            IpDadStateTentative,
            IpDadStateDuplicate,
            IpDadStateDeprecated,
            IpDadStatePreferred,
        }

        public enum NET_IF_CONNECTION_TYPE : uint
        {
            NET_IF_CONNECTION_DEDICATED = 1,
            NET_IF_CONNECTION_PASSIVE = 2,
            NET_IF_CONNECTION_DEMAND = 3,
            NET_IF_CONNECTION_MAXIMUM = 4
        }

        public enum TUNNEL_TYPE : uint {
            TUNNEL_TYPE_NONE = 0,
            TUNNEL_TYPE_OTHER = 1,
            TUNNEL_TYPE_DIRECT = 2,
            TUNNEL_TYPE_6TO4 = 11,
            TUNNEL_TYPE_ISATAP = 13,
            TUNNEL_TYPE_TEREDO = 14,
            TUNNEL_TYPE_IPHTTPS = 15
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct GUID {
            uint Data1;
            ushort Data2;
            ushort Data3;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
            byte[] Data4;
        }

        private const int MAX_ADAPTER_ADDRESS_LENGTH = 8;
        private const int MAX_ADAPTER_NAME_LENGTH = 256;
        private const int MAX_DHCPV6_DUID_LENGTH = 130;

        [StructLayout(LayoutKind.Sequential)]
        public struct SOCKADDR
        {
            /// u_short->unsigned short
            public ushort sa_family;

            /// char[14]
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 14)]
            public byte[] sa_data;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct SOCKET_ADDRESS
        {
            public IntPtr lpSockAddr;
            public int iSockaddrLength;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct IP_ADAPTER_UNICAST_ADDRESS
        {
            public UInt64 Alignment;
            public IntPtr Next;
            public SOCKET_ADDRESS Address;
            public IP_PREFIX_ORIGIN PrefixOrigin;
            public IP_SUFFIX_ORIGIN SuffixOrigin;
            public IP_DAD_STATE DadState;
            public uint ValidLifetime;
            public uint PreferredLifetime;
            public uint LeaseLifetime;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct IP_ADAPTER_ADDRESSES
        {
            public UInt64 Alignment;
            public IntPtr Next;
            public IntPtr AdapterName;
            public IntPtr FirstUnicastAddress;
            public IntPtr FirstAnycastAddress;
            public IntPtr FirstMulticastAddress;
            public IntPtr FirstDnsServerAddress;
            [MarshalAs(UnmanagedType.LPWStr)]
            public string DnsSuffix;
            [System.Runtime.InteropServices.MarshalAs(UnmanagedType.LPWStr)]
            public string Description;
            [System.Runtime.InteropServices.MarshalAs(UnmanagedType.LPWStr)]
            public string FriendlyName;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = MAX_ADAPTER_ADDRESS_LENGTH)]
            public byte[] PhysicalAddress;
            public uint PhysicalAddressLength;
            public uint Flags;
            public uint Mtu;
            public IF_TYPE IfType;
            public IF_OPER_STATUS OperStatus;
            uint Ipv6IfIndex;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 16)]
            public uint[] ZoneIndices;
            public IntPtr FirstPrefix;

            // Items added for Vista
            // May need to be removed on Windows versions below Vista to work properly (?)
            public UInt64 TrasmitLinkSpeed;
            public UInt64 ReceiveLinkSpeed;
            public IntPtr FirstWinsServerAddress;
            public IntPtr FirstGatewayAddress;
            public uint Ipv4Metric;
            public uint Ipv6Metric;
            public UInt64 Luid;
            public SOCKET_ADDRESS Dhcpv4Server;
            public uint CompartmentId;
            public GUID NetworkGuid;
            public NET_IF_CONNECTION_TYPE ConnectionType;
            public TUNNEL_TYPE TunnelType;
            public SOCKET_ADDRESS Dhcpv6Server;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = MAX_DHCPV6_DUID_LENGTH)]
            public byte[] Dhcpv6ClientDuid;
            public uint Dhcpv6ClientDuidLength;
            public uint Dhcpv6Iaid;
            public uint FirstDnsSuffix;
        }

        [DllImport("iphlpapi.dll")]
        private static extern ERROR GetAdaptersAddresses(uint Family, uint Flags, IntPtr Reserved, IntPtr pAdapterAddresses, ref uint pOutBufLen);

        public static string MarshalString(IntPtr text)
        {
            // !!!: This should only be used with IP_ADAPTER_ADDRESSES.AdapterName since it can't be marshalled automatically
            byte[] cName = new byte[MAX_ADAPTER_NAME_LENGTH];
            Marshal.Copy(text, cName, 0, MAX_ADAPTER_NAME_LENGTH);
            string name = Encoding.ASCII.GetString(cName, 0, MAX_ADAPTER_NAME_LENGTH);

            return name;
        }

        public static IList<IP_ADAPTER_ADDRESSES> GetIPAdapters(FAMILY family)
        {
            List<IP_ADAPTER_ADDRESSES> adapters = new List<IP_ADAPTER_ADDRESSES>();
            uint outBufLen = 0;
            ERROR err = GetAdaptersAddresses((uint)family, (uint)0, IntPtr.Zero, IntPtr.Zero, ref outBufLen);

            if (ERROR.ERROR_BUFFER_OVERFLOW == err)
            {
                IntPtr pAdapterAddresses = Marshal.AllocHGlobal((int)outBufLen);
                try
                {
                    err = GetAdaptersAddresses((uint)FAMILY.AF_INET, (uint)0, IntPtr.Zero, pAdapterAddresses, ref outBufLen);
                    if (ERROR.ERROR_SUCCESS == err)
                    {
                        IntPtr currPtr = pAdapterAddresses;
                        while (IntPtr.Zero != currPtr)
                        {
                            IP_ADAPTER_ADDRESSES addr = (IP_ADAPTER_ADDRESSES)Marshal.PtrToStructure(currPtr, typeof(IP_ADAPTER_ADDRESSES));
                            adapters.Add(addr);

                            currPtr = addr.Next;
                        }
                    }
                }
                finally
                {
                    Marshal.FreeHGlobal(pAdapterAddresses);
                }
            }

            return adapters;
        }

        public static IList<IPAddress> GetIPAddresses(FAMILY family)
        {
            List<IPAddress> addresses = new List<IPAddress>();

            foreach (IP_ADAPTER_ADDRESSES addr in GetIPAdapters(family)) {
                if (IntPtr.Zero != addr.FirstUnicastAddress)
                {
                    IP_ADAPTER_UNICAST_ADDRESS unicastAddr = (IP_ADAPTER_UNICAST_ADDRESS)Marshal.PtrToStructure(addr.FirstUnicastAddress, typeof(IP_ADAPTER_UNICAST_ADDRESS));
                    if (IntPtr.Zero != unicastAddr.Address.lpSockAddr)
                    {
                        SOCKADDR socketAddr = (SOCKADDR)Marshal.PtrToStructure(unicastAddr.Address.lpSockAddr, typeof(SOCKADDR));
                        byte[] saData = socketAddr.sa_data.Skip(2).Take(4).ToArray();
                        IPAddress ipAddr = new IPAddress(saData);
                        addresses.Add(ipAddr);
                    }
                }
            }

            return addresses;
        }
    }
}