System.Net.Sockets.Socket.GetIPProtocolInformation C# (CSharp) Method

        internal static void GetIPProtocolInformation(AddressFamily addressFamily, Internals.SocketAddress socketAddress, out bool isIPv4, out bool isIPv6)
        {
            bool isIPv4MappedToIPv6 = socketAddress.Family == AddressFamily.InterNetworkV6 && socketAddress.GetIPAddress().IsIPv4MappedToIPv6;
            isIPv4 = addressFamily == AddressFamily.InterNetwork || isIPv4MappedToIPv6; // DualMode
            isIPv6 = addressFamily == AddressFamily.InterNetworkV6;
        }

        // SetUnmanagedStructures
        //
        // Fills in overlapped Structures used in an async overlapped Winsock call.
        // These calls are outside the runtime and are unmanaged code, so we need
        // to prepare specific structures and ints that lie in unmanaged memory
        // since the overlapped calls may complete asynchronously.
        internal void SetUnmanagedStructures(byte[] buffer, int offset, int size, Internals.SocketAddress socketAddress, SocketFlags socketFlags)
        {
            _messageBuffer  = new byte[s_wsaMsgSize];
            _wsaBufferArray = new byte[s_wsaBufferSize];

            bool ipv4, ipv6;

            Socket.GetIPProtocolInformation(((Socket)AsyncObject).AddressFamily, socketAddress, out ipv4, out ipv6);

            // Prepare control buffer.
            if (ipv4)
            {
                _controlBuffer = new byte[s_controlDataSize];
            }
            else if (ipv6)
            {
                _controlBuffer = new byte[s_controlDataIPv6Size];
            }

            // Pin buffers.
            object[] objectsToPin = new object[(_controlBuffer != null) ? 5 : 4];
            objectsToPin[0] = buffer;
            objectsToPin[1] = _messageBuffer;
            objectsToPin[2] = _wsaBufferArray;

            // Prepare socketaddress buffer.
            _socketAddress = socketAddress;
            _socketAddress.CopyAddressSizeIntoBuffer();
            objectsToPin[3] = _socketAddress.Buffer;

            if (_controlBuffer != null)
            {
                objectsToPin[4] = _controlBuffer;
            }

            base.SetUnmanagedStructures(objectsToPin);

            // Prepare data buffer.
            _wsaBuffer          = (WSABuffer *)Marshal.UnsafeAddrOfPinnedArrayElement(_wsaBufferArray, 0);
            _wsaBuffer->Length  = size;
            _wsaBuffer->Pointer = Marshal.UnsafeAddrOfPinnedArrayElement(buffer, offset);


            // Setup structure.
            _message = (Interop.Winsock.WSAMsg *)Marshal.UnsafeAddrOfPinnedArrayElement(_messageBuffer, 0);
            _message->socketAddress = Marshal.UnsafeAddrOfPinnedArrayElement(_socketAddress.Buffer, 0);
            _message->addressLength = (uint)_socketAddress.Size;
            _message->buffers       = Marshal.UnsafeAddrOfPinnedArrayElement(_wsaBufferArray, 0);
            _message->count         = 1;

            if (_controlBuffer != null)
            {
                _message->controlBuffer.Pointer = Marshal.UnsafeAddrOfPinnedArrayElement(_controlBuffer, 0);
                _message->controlBuffer.Length  = _controlBuffer.Length;
            }

            _message->flags = socketFlags;
        }