public override Task <Mapping> GetSpecificMappingAsync(Protocol protocol, int publicPort)
        {
            Guard.IsTrue(protocol == Protocol.Tcp || protocol == Protocol.Udp, "protocol");
            Guard.IsInRange(publicPort, 0, ushort.MaxValue, "port");

            NatDiscoverer.TraceSource.LogInfo("GetSpecificMappingAsync - Getting mapping for protocol: {0} port: {1}", Enum.GetName(typeof(Protocol), protocol), publicPort);

            var message = new GetSpecificPortMappingEntryRequestMessage(protocol, publicPort);

            return(_soapClient
                   .InvokeAsync("GetSpecificPortMappingEntry", message.ToXml())
                   .TimeoutAfter(TimeSpan.FromSeconds(4))
                   .ContinueWith(task =>
            {
                if (!task.IsFaulted)
                {
                    var responseData = task.Result;

                    var messageResponse = new GetPortMappingEntryResponseMessage(responseData, DeviceInfo.ServiceType, false);

                    return new Mapping(messageResponse.Protocol
                                       , IPAddress.Parse(messageResponse.InternalClient)
                                       , messageResponse.InternalPort
                                       , publicPort // messageResponse.ExternalPort is short.MaxValue
                                       , messageResponse.LeaseDuration
                                       , messageResponse.PortMappingDescription);
                }
                else
                {
                    MappingException e = task.Exception.InnerException as MappingException;
                    if (e != null && e.ErrorCode == UpnpConstants.NoSuchEntryInArray)
                    {
                        return null;
                    }

                    // DD-WRT Linux base router (and others probably) fails with 402-InvalidArgument
                    // when no mapping is found in the mappings table
                    if (e != null && e.ErrorCode == UpnpConstants.InvalidArguments)
                    {
                        NatDiscoverer.TraceSource.LogWarn("Router failed with 402-InvalidArgument. Mapping not found is assumed.");
                        return null;
                    }
                    throw task.Exception.InnerException;
                }
            }));
        }
        public void GetGenericMappingAsync(int index, List <Mapping> mappings,
                                           TaskCompletionSource <IEnumerable <Mapping> > taskCompletionSource)
        {
            var message = new GetGenericPortMappingEntry(index);

            _soapClient
            .InvokeAsync("GetGenericPortMappingEntry", message.ToXml())
            .TimeoutAfter(TimeSpan.FromSeconds(4))
            .ContinueWith(task =>
            {
                if (!task.IsFaulted)
                {
                    var responseData    = task.Result;
                    var responseMessage = new GetPortMappingEntryResponseMessage(responseData,
                                                                                 DeviceInfo.ServiceType, true);

                    IPAddress internalClientIp;
                    if (!IPAddress.TryParse(responseMessage.InternalClient, out internalClientIp))
                    {
                        NatDiscoverer.TraceSource.LogWarn("InternalClient is not an IP address. Mapping ignored!");
                    }
                    else
                    {
                        var mapping = new Mapping(responseMessage.Protocol
                                                  , internalClientIp
                                                  , responseMessage.InternalPort
                                                  , responseMessage.ExternalPort
                                                  , responseMessage.LeaseDuration
                                                  , responseMessage.PortMappingDescription);
                        mappings.Add(mapping);
                    }

                    GetGenericMappingAsync(index + 1, mappings, taskCompletionSource);
                }
                else
                {
                    MappingException e = task.Exception.InnerException as MappingException;

                    if (e == null)
                    {
                        throw task.Exception.InnerException;
                    }

                    if (e.ErrorCode == UpnpConstants.SpecifiedArrayIndexInvalid ||
                        e.ErrorCode == UpnpConstants.NoSuchEntryInArray)
                    {
                        // there are no more mappings
                        taskCompletionSource.SetResult(mappings);
                        return;
                    }

                    // DD-WRT Linux base router (and others probably) fails with 402-InvalidArgument when index is out of range
                    if (e.ErrorCode == UpnpConstants.InvalidArguments)
                    {
                        NatDiscoverer.TraceSource.LogWarn("Router failed with 402-InvalidArgument. No more mappings is assumed.");
                        taskCompletionSource.SetResult(mappings);
                        return;
                    }

                    throw task.Exception.InnerException;
                }
            });
        }