func (d *tcpDialer) reuseDial(raddr ma.Multiaddr) (manet.Conn, error) {
	logdial := lgbl.Dial("conn", "", "", d.laddr, raddr)
	rpev := log.EventBegin(context.TODO(), "tptDialReusePort", logdial)

	network, netraddr, err := manet.DialArgs(raddr)
	if err != nil {
		return nil, err
	}

	con, err := d.rd.Dial(network, netraddr)
	if err == nil {
		logdial["reuseport"] = "success"
		rpev.Done()
		return manet.WrapNetConn(con)
	}

	if !ReuseErrShouldRetry(err) {
		logdial["reuseport"] = "failure"
		logdial["error"] = err
		rpev.Done()
		return nil, err
	}

	logdial["reuseport"] = "retry"
	logdial["error"] = err
	rpev.Done()

	return d.madialer.Dial(raddr)
}

func reuseDial(dialer net.Dialer, laddr, raddr ma.Multiaddr) (conn net.Conn, retry bool, err error) {
	if laddr == nil {
		// if we're given no local address no sense in using reuseport to dial, dial out as usual.
		return nil, true, reuseport.ErrReuseFailed
	}

	// give reuse.Dialer the manet.Dialer's Dialer.
	// (wow, Dialer should've so been an interface...)
	rd := reuseport.Dialer{dialer}

	// get the local net.Addr manually
	rd.D.LocalAddr, err = manet.ToNetAddr(laddr)
	if err != nil {
		return nil, true, err // something wrong with laddr. retry without.
	}

	// get the raddr dial args for rd.dial
	network, netraddr, err := manet.DialArgs(raddr)
	if err != nil {
		return nil, true, err // something wrong with laddr. retry without.
	}

	// rd.Dial gets us a net.Conn with SO_REUSEPORT and SO_REUSEADDR set.
	conn, err = rd.Dial(network, netraddr)
	return conn, reuseErrShouldRetry(err), err // hey! it worked!
}

func apiClientForAddr(addr ma.Multiaddr) (cmdsHttp.Client, error) {
	_, host, err := manet.DialArgs(addr)
	if err != nil {
		return nil, err
	}

	return cmdsHttp.NewClient(host), nil
}

// rawConnDial dials the underlying net.Conn + manet.Conns
func (d *Dialer) rawConnDial(ctx context.Context, raddr ma.Multiaddr, remote peer.ID) (manet.Conn, error) {

	// before doing anything, check we're going to be able to dial.
	// we may not support the given address.
	if _, _, err := manet.DialArgs(raddr); err != nil {
		return nil, err
	}

	if strings.HasPrefix(raddr.String(), "/ip4/0.0.0.0") {
		log.Event(ctx, "connDialZeroAddr", lgbl.Dial("conn", d.LocalPeer, remote, nil, raddr))
		return nil, fmt.Errorf("Attempted to connect to zero address: %s", raddr)
	}

	// get local addr to use.
	laddr := pickLocalAddr(d.LocalAddrs, raddr)
	logdial := lgbl.Dial("conn", d.LocalPeer, remote, laddr, raddr)
	defer log.EventBegin(ctx, "connDialRawConn", logdial).Done()

	// make a copy of the manet.Dialer, we may need to change its timeout.
	madialer := d.Dialer

	if laddr != nil && reuseportIsAvailable() {
		// we're perhaps going to dial twice. half the timeout, so we can afford to.
		// otherwise our context would expire right after the first dial.
		madialer.Dialer.Timeout = (madialer.Dialer.Timeout / 2)

		// dial using reuseport.Dialer, because we're probably reusing addrs.
		// this is optimistic, as the reuseDial may fail to bind the port.
		rpev := log.EventBegin(ctx, "connDialReusePort", logdial)
		if nconn, retry, reuseErr := reuseDial(madialer.Dialer, laddr, raddr); reuseErr == nil {
			// if it worked, wrap the raw net.Conn with our manet.Conn
			logdial["reuseport"] = "success"
			rpev.Done()
			return manet.WrapNetConn(nconn)
		} else if !retry {
			// reuseDial is sure this is a legitimate dial failure, not a reuseport failure.
			logdial["reuseport"] = "failure"
			logdial["error"] = reuseErr
			rpev.Done()
			return nil, reuseErr
		} else {
			// this is a failure to reuse port. log it.
			logdial["reuseport"] = "retry"
			logdial["error"] = reuseErr
			rpev.Done()
		}
	}

	defer log.EventBegin(ctx, "connDialManet", logdial).Done()
	return madialer.Dial(raddr)
}

func (f *Filters) AddrBlocked(a ma.Multiaddr) bool {
	_, addr, err := manet.DialArgs(a)
	if err != nil {
		// if we cant parse it, its probably not blocked
		return false
	}

	ipstr := strings.Split(addr, ":")[0]
	ip := net.ParseIP(ipstr)
	for _, ft := range f.filters {
		if ft.Contains(ip) {
			return true
		}
	}
	return false
}

// 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 main() {
	flag.Parse()

	// extract address from host flag
	addr, err := ma.NewMultiaddr(*host)
	if err != nil {
		log.Fatal("NewMultiaddr() failed: ", err)
	}
	p := addr.Protocols()
	if len(p) < 2 {
		log.Fatal("need two protocols in host flag (/ip/tcp): ", addr)
	}
	_, host, err := manet.DialArgs(addr)
	if err != nil {
		log.Fatal("manet.DialArgs() failed: ", err)
	}

	if *verbose { // lower log level
		logging.SetDebugLogging()
	}

	// construct url to dial
	var u url.URL
	u.Scheme = "http"
	u.Host = host
	u.Path = *endpoint

	// show what we got
	start := time.Now()
	log.Debug("starting at %s, tries: %d, timeout: %s, url: %s", start, *tries, *timeout, u)

	for *tries > 0 {

		err := checkOK(http.Get(u.String()))
		if err == nil {
			log.Debugf("ok -  endpoint reachable with %d tries remaining, took %s", *tries, time.Since(start))
			os.Exit(0)
		}
		log.Debug("get failed: ", err)
		time.Sleep(*timeout)
		*tries--
	}

	log.Error("failed.")
	os.Exit(1)
}

func getNodesAPIAddr(nnum int) (string, error) {
	addrb, err := ioutil.ReadFile(path.Join(IpfsDirN(nnum), "api"))
	if err != nil {
		return "", err
	}

	maddr, err := ma.NewMultiaddr(string(addrb))
	if err != nil {
		fmt.Println("error parsing multiaddr: ", err)
		return "", err
	}

	_, addr, err := manet.DialArgs(maddr)
	if err != nil {
		fmt.Println("error on multiaddr dialargs: ", err)
		return "", err
	}
	return addr, nil
}

func manetListen(addr ma.Multiaddr) (manet.Listener, error) {
	network, naddr, err := manet.DialArgs(addr)
	if err != nil {
		return nil, err
	}

	if ReuseportIsAvailable() {
		nl, err := reuseport.Listen(network, naddr)
		if err == nil {
			// hey, it worked!
			return manet.WrapNetListener(nl)
		}
		// reuseport is available, but we failed to listen. log debug, and retry normally.
		log.Debugf("reuseport available, but failed to listen: %s %s, %s", network, naddr, err)
	}

	// either reuseport not available, or it failed. try normally.
	return manet.Listen(addr)
}

func (s *UtpSocket) Dial(raddr ma.Multiaddr) (Conn, error) {
	_, addr, err := manet.DialArgs(raddr)
	if err != nil {
		return nil, err
	}

	con, err := s.s.Dial(addr)
	if err != nil {
		return nil, err
	}

	mnc, err := manet.WrapNetConn(&mautp.Conn{Conn: con})
	if err != nil {
		return nil, err
	}

	return &connWrap{
		Conn:      mnc,
		transport: s.transport,
	}, nil
}

func (t *UtpTransport) newConn(addr ma.Multiaddr, opts ...DialOpt) (*UtpSocket, error) {
	network, netaddr, err := manet.DialArgs(addr)
	if err != nil {
		return nil, err
	}

	s, err := utp.NewSocket("udp"+network[3:], netaddr)
	if err != nil {
		return nil, err
	}

	laddr, err := manet.FromNetAddr(mautp.MakeAddr(s.LocalAddr()))
	if err != nil {
		return nil, err
	}

	return &UtpSocket{
		s:         s,
		laddr:     laddr,
		transport: t,
	}, nil
}

func IpfsStart(waitall bool) error {
	var addrs []string
	n := GetNumNodes()
	for i := 0; i < n; i++ {
		dir := IpfsDirN(i)
		cmd := exec.Command("ipfs", "daemon")
		cmd.Dir = dir
		cmd.Env = envForDaemon(i)

		setupOpt(cmd)

		stdout, err := os.Create(path.Join(dir, "daemon.stdout"))
		if err != nil {
			return err
		}

		stderr, err := os.Create(path.Join(dir, "daemon.stderr"))
		if err != nil {
			return err
		}

		cmd.Stdout = stdout
		cmd.Stderr = stderr

		err = cmd.Start()
		if err != nil {
			return err
		}
		pid := cmd.Process.Pid

		fmt.Printf("Started daemon %d, pid = %d\n", i, pid)
		err = ioutil.WriteFile(path.Join(dir, "daemon.pid"), []byte(fmt.Sprint(pid)), 0666)
		if err != nil {
			return err
		}

		// Make sure node 0 is up before starting the rest so
		// bootstrapping works properly
		cfg, err := serial.Load(path.Join(IpfsDirN(i), "config"))
		if err != nil {
			return err
		}

		maddr := ma.StringCast(cfg.Addresses.API)
		_, addr, err := manet.DialArgs(maddr)
		if err != nil {
			return err
		}

		addrs = append(addrs, addr)

		err = waitOnAPI(cfg.Identity.PeerID, i)
		if err != nil {
			return err
		}
	}
	if waitall {
		for i := 0; i < n; i++ {
			err := waitOnSwarmPeers(i)
			if err != nil {
				return err
			}
		}

	}
	return nil
}

func callCommand(ctx context.Context, req cmds.Request, root *cmds.Command, cmd *cmds.Command) (cmds.Response, error) {
	log.Info(config.EnvDir, " ", req.InvocContext().ConfigRoot)
	var res cmds.Response

	err := req.SetRootContext(ctx)
	if err != nil {
		return nil, err
	}

	details, err := commandDetails(req.Path(), root)
	if err != nil {
		return nil, err
	}

	log.Debug("looking for running daemon...")
	useDaemon, err := commandShouldRunOnDaemon(*details, req, root)
	if err != nil {
		return nil, err
	}

	err = callPreCommandHooks(ctx, *details, req, root)
	if err != nil {
		return nil, err
	}

	if cmd.PreRun != nil {
		err = cmd.PreRun(req)
		if err != nil {
			return nil, err
		}
	}

	if useDaemon {

		cfg, err := req.InvocContext().GetConfig()
		if err != nil {
			return nil, err
		}

		addr, err := ma.NewMultiaddr(cfg.Addresses.API)
		if err != nil {
			return nil, err
		}

		log.Infof("Executing command on daemon running at %s", addr)
		_, host, err := manet.DialArgs(addr)
		if err != nil {
			return nil, err
		}

		client := cmdsHttp.NewClient(host)

		res, err = client.Send(req)
		if err != nil {
			return nil, err
		}

	} else {
		log.Debug("Executing command locally")

		err := req.SetRootContext(ctx)
		if err != nil {
			return nil, err
		}

		// Okay!!!!! NOW we can call the command.
		res = root.Call(req)

	}

	if cmd.PostRun != nil {
		cmd.PostRun(req, res)
	}

	return res, nil
}