func addPortMapping(nmgr *natManager, intaddr ma.Multiaddr) {
nat := nmgr.NAT()
if nat == nil {
panic("natManager addPortMapping called without a nat.")
}
// first, check if the port mapping already exists.
for _, mapping := range nat.Mappings() {
if mapping.InternalAddr().Equal(intaddr) {
return // it exists! return.
}
}
ctx := context.TODO()
lm := make(lgbl.DeferredMap)
lm["internalAddr"] = func() interface{} { return intaddr.String() }
defer log.EventBegin(ctx, "natMgrAddPortMappingWait", lm).Done()
select {
case <-nmgr.proc.Closing():
lm["outcome"] = "cancelled"
return // no use.
case <-nmgr.ready: // wait until it's ready.
}
// actually start the port map (sub-event because waiting may take a while)
defer log.EventBegin(ctx, "natMgrAddPortMapping", lm).Done()
// get the nat
m, err := nat.NewMapping(intaddr)
if err != nil {
lm["outcome"] = "failure"
lm["error"] = err
return
}
extaddr, err := m.ExternalAddr()
if err != nil {
lm["outcome"] = "failure"
lm["error"] = err
return
}
lm["outcome"] = "success"
lm["externalAddr"] = func() interface{} { return extaddr.String() }
log.Infof("established nat port mapping: %s <--> %s", intaddr, extaddr)
}
// 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
}