///////////////////////////////////////////////////////////////////////////////////////////////////////////////
        #endregion
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////

        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////
        #region Update Port Mappings Thread
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////

        private void UpdatePortMappingsThread()
        {
            Monitor.Enter(multiThreadLock);
            OnDidBeginWorking();

            NATPMP.natpmp_t natpmp = new NATPMP.natpmp_t();
            NATPMP.initnatpmp(ref natpmp);

            // Remove mappings scheduled for removal

            List <PortMapping> mappingsToRemove = PortMapper.SharedInstance.PortMappingsToRemove;

            lock (mappingsToRemove)
            {
                while ((mappingsToRemove.Count > 0) && (updatePortMappingsThreadFlags == ThreadFlags.None))
                {
                    PortMapping mappingToRemove = mappingsToRemove[0];

                    if (mappingToRemove.MappingStatus == PortMappingStatus.Mapped)
                    {
                        RemovePortMapping(mappingToRemove, ref natpmp);
                    }

                    mappingsToRemove.RemoveAt(0);
                }
            }

            // If the port mapper is running:
            //   -Refresh existing mappings
            //   -Add new mappings
            // If the port mapper is stopped:
            //   -Remove any existing mappings

            List <PortMapping> mappings = PortMapper.SharedInstance.PortMappings;

            lock (mappings)
            {
                for (int i = 0; i < mappings.Count && updatePortMappingsThreadFlags == ThreadFlags.None; i++)
                {
                    PortMapping existingMapping = mappings[i];
                    bool        isRunning       = PortMapper.SharedInstance.IsRunning;

                    if (existingMapping.MappingStatus == PortMappingStatus.Mapped)
                    {
                        if (isRunning)
                        {
                            RefreshPortMapping(existingMapping, ref natpmp);
                        }
                        else
                        {
                            RemovePortMapping(existingMapping, ref natpmp);
                        }
                    }
                }

                for (int i = 0; i < mappings.Count && updatePortMappingsThreadFlags == ThreadFlags.None; i++)
                {
                    PortMapping mappingToAdd = mappings[i];
                    bool        isRunning    = PortMapper.SharedInstance.IsRunning;

                    if (mappingToAdd.MappingStatus == PortMappingStatus.Unmapped && isRunning)
                    {
                        AddPortMapping(mappingToAdd, ref natpmp);
                    }
                }
            }

            NATPMP.closenatpmp(ref natpmp);
            Monitor.Exit(multiThreadLock);

            if (PortMapper.SharedInstance.IsRunning)
            {
                if ((updatePortMappingsThreadFlags & ThreadFlags.ShouldRestart) > 0)
                {
                    UpdatePortMappings();
                }
                else if ((updatePortMappingsThreadFlags & ThreadFlags.ShouldQuit) > 0)
                {
                    Refresh();
                }
                else
                {
                    AdjustUpdateTimer();
                }
            }

            OnDidEndWorking();
        }
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////
        #endregion
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////

        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////
        #region Refresh External IP Thread
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////

        private void RefreshExternalIPThread()
        {
            Monitor.Enter(multiThreadLock);
            OnDidBeginWorking();

            NATPMP.natpmp_t     natpmp   = new NATPMP.natpmp_t();
            NATPMP.natpmpresp_t response = new NATPMP.natpmpresp_t();
            int r;

            Win32.TimeValue         timeout = new Win32.TimeValue();
            Win32.FileDescriptorSet fds     = new Win32.FileDescriptorSet(1);
            bool didFail = false;

            r = NATPMP.initnatpmp(ref natpmp);
            if (r < 0)
            {
                didFail = true;
            }
            else
            {
                r = NATPMP.sendpublicaddressrequest(ref natpmp);
                if (r < 0)
                {
                    didFail = true;
                }
                else
                {
                    do
                    {
                        fds.Count    = 1;
                        fds.Array[0] = (IntPtr)natpmp.s;
                        NATPMP.getnatpmprequesttimeout(ref natpmp, ref timeout);

                        Win32.select(0, ref fds, IntPtr.Zero, IntPtr.Zero, ref timeout);

                        r = NATPMP.readnatpmpresponseorretry(ref natpmp, ref response);
                        if (refreshExternalIPThreadFlags != ThreadFlags.None)
                        {
                            DebugLog.WriteLine("NAT-PMP: RefreshExternalIPThread quit prematurely (1)");

                            Monitor.Exit(multiThreadLock);
                            if ((refreshExternalIPThreadFlags & ThreadFlags.ShouldRestart) > 0)
                            {
                                Refresh();
                            }
                            NATPMP.closenatpmp(ref natpmp);
                            OnDidEndWorking();
                            return;
                        }
                    }while (r == NATPMP.ERR_TRYAGAIN);

                    if (r < 0)
                    {
                        didFail = true;
                        DebugLog.WriteLine("NAT-PMP: IP refresh did time out");
                    }
                    else
                    {
                        IPAddress ipaddr = new IPAddress((long)response.pnu_publicaddress.addr);
                        OnDidGetExternalIPAddress(ipaddr);
                    }
                }
            }

            NATPMP.closenatpmp(ref natpmp);
            Monitor.Exit(multiThreadLock);

            if (refreshExternalIPThreadFlags != ThreadFlags.None)
            {
                DebugLog.WriteLine("NAT-PMP: RefreshExternalIPThread quit prematurely (2)");

                if ((refreshExternalIPThreadFlags & ThreadFlags.ShouldRestart) > 0)
                {
                    Refresh();
                }
            }
            else
            {
                if (didFail)
                {
                    OnDidFail();
                }
                else
                {
                    UpdatePortMappings();
                }
            }
            OnDidEndWorking();
        }