Table of Contents

Class Upnp

Namespace
Godot
Assembly
GodotSharp.dll

This class can be used to discover compatible UpnpDevices on the local network and execute commands on them, like managing port mappings (for port forwarding/NAT traversal) and querying the local and remote network IP address. Note that methods on this class are synchronous and block the calling thread.

To forward a specific port (here 7777, note both Discover(int, int, string) and AddPortMapping(int, int, string, string, int) can return errors that should be checked):

var upnp = UPNP.new()
  upnp.discover()
  upnp.add_port_mapping(7777)

To close a specific port (e.g. after you have finished using it):

upnp.delete_port_mapping(port)

Note: UPnP discovery blocks the current thread. To perform discovery without blocking the main thread, use GodotThreads like this:

# Emitted when UPnP port mapping setup is completed (regardless of success or failure).
  signal upnp_completed(error)

Replace this with your own server port number between 1024 and 65535.


const SERVER_PORT = 3928
var thread = null


func _upnp_setup(server_port):
# UPNP queries take some time.
var upnp = UPNP.new()
var err = upnp.discover()


  if err != OK:
      push_error(str(err))
      emit_signal("upnp_completed", err)
      return

  if upnp.get_gateway() and upnp.get_gateway().is_valid_gateway():
      upnp.add_port_mapping(server_port, server_port, ProjectSettings.get_setting("application/config/name"), "UDP")
      upnp.add_port_mapping(server_port, server_port, ProjectSettings.get_setting("application/config/name"), "TCP")
      emit_signal("upnp_completed", OK)



func _ready():
thread = Thread.new()
thread.start(_upnp_setup.bind(SERVER_PORT))


func _exit_tree():
# Wait for thread finish here to handle game exit while the thread is running.
thread.wait_to_finish()

Terminology: In the context of UPnP networking, "gateway" (or "internet gateway device", short IGD) refers to network devices that allow computers in the local network to access the internet ("wide area network", WAN). These gateways are often also called "routers".

Pitfalls:

- As explained above, these calls are blocking and shouldn't be run on the main thread, especially as they can block for multiple seconds at a time. Use threading!

- Networking is physical and messy. Packets get lost in transit or get filtered, addresses, free ports and assigned mappings change, and devices may leave or join the network at any time. Be mindful of this, be diligent when checking and handling errors, and handle these gracefully if you can: add clear error UI, timeouts and re-try handling.

- Port mappings may change (and be removed) at any time, and the remote/external IP address of the gateway can change likewise. You should consider re-querying the external IP and try to update/refresh the port mapping periodically (for example, every 5 minutes and on networking failures).

- Not all devices support UPnP, and some users disable UPnP support. You need to handle this (e.g. documenting and requiring the user to manually forward ports, or adding alternative methods of NAT traversal, like a relay/mirror server, or NAT hole punching, STUN/TURN, etc.).

- Consider what happens on mapping conflicts. Maybe multiple users on the same network would like to play your game at the same time, or maybe another application uses the same port. Make the port configurable, and optimally choose a port automatically (re-trying with a different port on failure).

Further reading: If you want to know more about UPnP (and the Internet Gateway Device (IGD) and Port Control Protocol (PCP) specifically), Wikipedia is a good first stop, the specification can be found at the Open Connectivity Foundation and Godot's implementation is based on the MiniUPnP client.

[GodotClassName("UPNP")]
public class Upnp : RefCounted, IDisposable
Inheritance
Upnp
Implements
Inherited Members

Constructors

Upnp() 

public Upnp()

Properties

DiscoverIpv6

If true, IPv6 is used for UpnpDevice discovery.

public bool DiscoverIpv6 { get; set; }

Property Value

bool

DiscoverLocalPort

If 0, the local port to use for discovery is chosen automatically by the system. If 1, discovery will be done from the source port 1900 (same as destination port). Otherwise, the value will be used as the port.

public int DiscoverLocalPort { get; set; }

Property Value

int

DiscoverMulticastIf

Multicast interface to use for discovery. Uses the default multicast interface if empty.

public string DiscoverMulticastIf { get; set; }

Property Value

string

Methods

AddDevice(UpnpDevice)

Adds the given UpnpDevice to the list of discovered devices.

public void AddDevice(UpnpDevice device)

Parameters

device UpnpDevice

AddPortMapping(int, int, string, string, int)

Adds a mapping to forward the external port (between 1 and 65535, although recommended to use port 1024 or above) on the default gateway (see GetGateway()) to the portInternal on the local machine for the given protocol proto (either "TCP" or "UDP", with UDP being the default). If a port mapping for the given port and protocol combination already exists on that gateway device, this method tries to overwrite it. If that is not desired, you can retrieve the gateway manually with GetGateway() and call AddPortMapping(int, int, string, string, int) on it, if any. Note that forwarding a well-known port (below 1024) with UPnP may fail depending on the device.

Depending on the gateway device, if a mapping for that port already exists, it will either be updated or it will refuse this command due to that conflict, especially if the existing mapping for that port wasn't created via UPnP or points to a different network address (or device) than this one.

If portInternal is 0 (the default), the same port number is used for both the external and the internal port (the port value).

The description (desc) is shown in some routers management UIs and can be used to point out which application added the mapping.

The mapping's lease duration can be limited by specifying a duration in seconds. The default of 0 means no duration, i.e. a permanent lease and notably some devices only support these permanent leases. Note that whether permanent or not, this is only a request and the gateway may still decide at any point to remove the mapping (which usually happens on a reboot of the gateway, when its external IP address changes, or on some models when it detects a port mapping has become inactive, i.e. had no traffic for multiple minutes). If not 0 (permanent), the allowed range according to spec is between 120 (2 minutes) and 86400 seconds (24 hours).

See Upnp.UpnpResult for possible return values.

public int AddPortMapping(int port, int portInternal = 0, string desc = "", string proto = "UDP", int duration = 0)

Parameters

port int
portInternal int
desc string
proto string
duration int

Returns

int

ClearDevices()

Clears the list of discovered devices.

public void ClearDevices()

DeletePortMapping(int, string)

Deletes the port mapping for the given port and protocol combination on the default gateway (see GetGateway()) if one exists. port must be a valid port between 1 and 65535, proto can be either "TCP" or "UDP". May be refused for mappings pointing to addresses other than this one, for well-known ports (below 1024), or for mappings not added via UPnP. See Upnp.UpnpResult for possible return values.

public int DeletePortMapping(int port, string proto = "UDP")

Parameters

port int
proto string

Returns

int

Discover(int, int, string)

Discovers local UpnpDevices. Clears the list of previously discovered devices.

Filters for IGD (InternetGatewayDevice) type devices by default, as those manage port forwarding. timeout is the time to wait for responses in milliseconds. ttl is the time-to-live; only touch this if you know what you're doing.

See Upnp.UpnpResult for possible return values.

public int Discover(int timeout = 2000, int ttl = 2, string deviceFilter = "InternetGatewayDevice")

Parameters

timeout int
ttl int
deviceFilter string

Returns

int

GetDevice(int)

Returns the UpnpDevice at the given index.

public UpnpDevice GetDevice(int index)

Parameters

index int

Returns

UpnpDevice

GetDeviceCount()

Returns the number of discovered UpnpDevices.

public int GetDeviceCount()

Returns

int

GetGateway()

Returns the default gateway. That is the first discovered UpnpDevice that is also a valid IGD (InternetGatewayDevice).

public UpnpDevice GetGateway()

Returns

UpnpDevice

HasGodotClassMethod(in godot_string_name)

Check if the type contains a method with the given name. This method is used by Godot to check if a method exists before invoking it. Do not call or override this method.

protected override bool HasGodotClassMethod(in godot_string_name method)

Parameters

method godot_string_name

Name of the method to check for.

Returns

bool

HasGodotClassSignal(in godot_string_name)

Check if the type contains a signal with the given name. This method is used by Godot to check if a signal exists before raising it. Do not call or override this method.

protected override bool HasGodotClassSignal(in godot_string_name signal)

Parameters

signal godot_string_name

Name of the signal to check for.

Returns

bool

InvokeGodotClassMethod(in godot_string_name, NativeVariantPtrArgs, out godot_variant)

Invokes the method with the given name, using the given arguments. This method is used by Godot to invoke methods from the engine side. Do not call or override this method.

protected override bool InvokeGodotClassMethod(in godot_string_name method, NativeVariantPtrArgs args, out godot_variant ret)

Parameters

method godot_string_name

Name of the method to invoke.

args NativeVariantPtrArgs

Arguments to use with the invoked method.

ret godot_variant

Value returned by the invoked method.

Returns

bool

QueryExternalAddress()

Returns the external IP address of the default gateway (see GetGateway()) as string. Returns an empty string on error.

public string QueryExternalAddress()

Returns

string

RemoveDevice(int)

Removes the device at index from the list of discovered devices.

public void RemoveDevice(int index)

Parameters

index int

SetDevice(int, UpnpDevice)

Sets the device at index from the list of discovered devices to device.

public void SetDevice(int index, UpnpDevice device)

Parameters

index int
device UpnpDevice
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