System.Net.Sockets.SocketPal.GetMulticastOption C# (CSharp) Метод

        public static unsafe SocketError GetMulticastOption(SafeCloseSocket handle, SocketOptionName optionName, out MulticastOption optionValue)
        {
            Debug.Assert(optionName == SocketOptionName.AddMembership || optionName == SocketOptionName.DropMembership, $"Unexpected optionName={optionName}");

            Interop.Sys.MulticastOption optName = optionName == SocketOptionName.AddMembership ?
                Interop.Sys.MulticastOption.MULTICAST_ADD :
                Interop.Sys.MulticastOption.MULTICAST_DROP;

            Interop.Sys.IPv4MulticastOption opt;
            Interop.Error err = Interop.Sys.GetIPv4MulticastOption(handle, optName, &opt);
            if (err != Interop.Error.SUCCESS)
            {
                optionValue = default(MulticastOption);
                return GetSocketErrorForErrorCode(err);
            }

            var multicastAddress = new IPAddress((long)opt.MulticastAddress);
            var localAddress = new IPAddress((long)opt.LocalAddress);
            optionValue = new MulticastOption(multicastAddress, localAddress) {
                InterfaceIndex = opt.InterfaceIndex
            };

            return SocketError.Success;
        }