type Client interface {// Probe returns a summary of which port mapping services are available on// the network.//// If a probe has run recently and there haven't been any network changes// since, the returned result might be server from the Client's cache,// without sending any network traffic.Probe(context.Context) (ProbeResult,error)// HaveMapping reports whether we have a current valid mapping.HaveMapping()bool// SetGatewayLookupFunc set the func that returns the machine's default// gateway IP, and the primary IP address for that gateway. It must be// called before the client is used. If not called,// interfaces.LikelyHomeRouterIP is used.SetGatewayLookupFunc(f func() (gw, myIPnetip.Addr, okbool))// NoteNetworkDown should be called when the network has transitioned to a down state.// It's too late to release port mappings at this point (the user might've just turned off// their wifi), but we can make sure we invalidate mappings for later when the network// comes back.NoteNetworkDown()// GetCachedMappingOrStartCreatingOne quickly returns with our current cached portmapping, if any.// If there's not one, it starts up a background goroutine to create one.// If the background goroutine ends up creating one, the onChange hook registered with the// NewClient constructor (if any) will fire.GetCachedMappingOrStartCreatingOne() (externalnetip.AddrPort, okbool)// SetLocalPort updates the local port number to which we want to port// map UDP trafficSetLocalPort(localPortuint16)Close()error}

type Mapping struct {Externalnetip.AddrPortTypestringGoodUntiltime.Time}

type ProbeResult struct {PCPboolPMPboolUPnPbool}