Example #1
0
// NewMapping attemps to construct a mapping on protocol and internal port
// It will also periodically renew the mapping until the returned Mapping
// -- or its parent NAT -- is Closed.
//
// May not succeed, and mappings may change over time;
// NAT devices may not respect our port requests, and even lie.
// Clients should not store the mapped results, but rather always
// poll our object for the latest mappings.
func (nat *NAT) NewMapping(maddr ma.Multiaddr) (Mapping, error) {
	if nat == nil {
		return nil, fmt.Errorf("no nat available")
	}

	network, addr, err := manet.DialArgs(maddr)
	if err != nil {
		return nil, fmt.Errorf("DialArgs failed on addr:", maddr.String())
	}

	switch network {
	case "tcp", "tcp4", "tcp6":
		network = "tcp"
	case "udp", "udp4", "udp6":
		network = "udp"
	default:
		return nil, fmt.Errorf("transport not supported by NAT: %s", network)
	}

	intports := strings.Split(addr, ":")[1]
	intport, err := strconv.Atoi(intports)
	if err != nil {
		return nil, err
	}

	m := &mapping{
		nat:     nat,
		proto:   network,
		intport: intport,
		intaddr: maddr,
	}
	m.proc = goprocess.WithTeardown(func() error {
		nat.rmMapping(m)
		return nil
	})
	nat.addMapping(m)

	m.proc.AddChild(periodic.Every(MappingDuration/3, func(worker goprocess.Process) {
		nat.establishMapping(m)
	}))

	// do it once synchronously, so first mapping is done right away, and before exiting,
	// allowing users -- in the optimistic case -- to use results right after.
	nat.establishMapping(m)
	return m, nil
}
func ExampleEvery() {
	tock := make(chan struct{})

	i := 0
	p := periodicproc.Every(time.Second, func(proc goprocess.Process) {
		tock <- struct{}{}
		fmt.Printf("hello %d\n", i)
		i++
	})

	<-tock
	<-tock
	<-tock
	p.Close()

	// Output:
	// hello 0
	// hello 1
	// hello 2
}