// lookupAddr resolves the given address/host to an IP address. If
// multiple addresses are resolved, it returns the first IPv4 address
// available if there is one, otherwise the first address.
427150
func lookupAddr(ctx context.Context, resolver *net.Resolver, host string) (string, error) {
	// Resolve the IP address or hostname to an IP address.
	addrs, err := resolver.LookupIPAddr(ctx, host)
	if err != nil {
		return "", errors.Wrap(err, "looking up IP addresses")
	}
	if len(addrs) == 0 {
		return "", fmt.Errorf("cannot resolve %q to an address", host)
	}

	// LookupIPAddr() can return a mix of IPv6 and IPv4
	// addresses. Return the first IPv4 address if possible.
	for _, addr := range addrs {
		if ip := addr.IP.To4(); ip != nil {
			return ip.String(), nil
		}
	}

	// No IPv4 address, return the first resolved address instead.
	return addrs[0].String(), nil
}
917374
func (h *HostInfo) ConnectAddress() net.IP {
	h.mu.RLock()
	defer h.mu.RUnlock()

	if addr, _ := h.connectAddressLocked(); validIpAddr(addr) {
		return addr
	}
	panic(fmt.Sprintf("no valid connect address for host: %v. Is your cluster configured correctly?", h))
}
1087415
func resolveAddresses(ctx context.Context, addrs []string) ([]ma.Multiaddr, error) {
	ctx, cancel := context.WithTimeout(ctx, dnsResolveTimeout)
	defer cancel()

	var maddrs []ma.Multiaddr
	var wg sync.WaitGroup
	resolveErrC := make(chan error, len(addrs))

	maddrC := make(chan ma.Multiaddr)

	for _, addr := range addrs {
		maddr, err := ma.NewMultiaddr(addr)
		if err != nil {
			return nil, err
		}

		// check whether address ends in `ipfs/Qm...`
		if _, last := ma.SplitLast(maddr); last.Protocol().Code == ma.P_IPFS {
			maddrs = append(maddrs, maddr)
			continue
		}
		wg.Add(1)
		go func(maddr ma.Multiaddr) {
			defer wg.Done()
			raddrs, err := madns.Resolve(ctx, maddr)
			if err != nil {
				resolveErrC <- err
				return
			}
			// filter out addresses that still doesn't end in `ipfs/Qm...`
			found := 0
			for _, raddr := range raddrs {
				if _, last := ma.SplitLast(raddr); last.Protocol().Code == ma.P_IPFS {
					maddrC <- raddr
					found++
				}
			}
			if found == 0 {
				resolveErrC <- fmt.Errorf("found no ipfs peers at %s", maddr)
			}
		}(maddr)
	}
	go func() {
		wg.Wait()
		close(maddrC)
	}()

	for maddr := range maddrC {
		maddrs = append(maddrs, maddr)
	}

	select {
	case err := <-resolveErrC:
		return nil, err
	default:
	}

	return maddrs, nil
}
586284
func (t *Transport) PeerAddr(id uint64) (string, error) {
	t.mu.Lock()
	defer t.mu.Unlock()
	p, ok := t.peers[id]
	if !ok {
		return "", ErrIsNotFound
	}
	return p.address(), nil
}
1213998
func (ipv4 IPv4Addr) ContainsAddress(x IPv4Address) bool {
	return IPv4Address(ipv4.NetworkAddress()) <= x &&
		IPv4Address(ipv4.BroadcastAddress()) >= x
}
1036720
func getAddr(addr string) (string, error) {
	if strings.Compare(addr, "0.0.0.0") == 0 {
		addrs, err := net.InterfaceAddrs()
		if err != nil {
			return "", err
		}
		for _, address := range addrs {
			// check the address type and if it is not a loopback the display it
			if ipnet, ok := address.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
				if ipnet.IP.To4() != nil {
					return ipnet.IP.String(), nil
				}
			}
		}
	}
	return addr, nil
}
848447
func GetIPv4Addresses() (ips []string, err error) {
	ips = []string{}

	addrs, err := net.InterfaceAddrs()
	if err != nil {
		return nil, fmt.Errorf("unable to use InterfaceAddrs to find local ipv4 addresses: %v", err)
	}

	for _, a := range addrs {
		if ipnet, ok := a.(*net.IPNet); ok && !ipnet.IP.IsLoopback() && nil != ipnet.IP.To4() {
			ips = append(ips, ipnet.IP.String())
		}
	}

	if len(ips) == 0 {
		return ips, fmt.Errorf("unable to identify local ip address")
	}

	return ips, nil
}
18518
func ResolveHostname(addr string) string {
	if idx := strings.IndexByte(addr, ':'); idx == 0 {
		// only port, then return the localhost hostname
		return "localhost"
	} else if idx > 0 {
		return addr[0:idx]
	}
	// it's already hostname
	return addr
}
1362541
func GetIfaceAddr(name string) (net.Addr, error) {
	iface, err := net.InterfaceByName(name)
	if err != nil {
		return nil, err
	}
	addrs, err := iface.Addrs()
	if err != nil {
		return nil, err
	}
	var addrs4 []net.Addr
	for _, addr := range addrs {
		ip := (addr.(*net.IPNet)).IP
		if ip4 := ip.To4(); len(ip4) == net.IPv4len {
			addrs4 = append(addrs4, addr)
		}
	}
	if len(addrs4) == 0 {
		return nil, ErrorNoIpv4
	}
	return addrs4[0], nil
}
351897
func LookupIPv4(ipv4 string) *endpoint.Endpoint {
	mutex.RLock()
	ep := lookupIPv4(ipv4)
	mutex.RUnlock()
	return ep
}
372561
func splitAddr(addr string) (string, string, string, error) {
	scheme, hostPort := splitScheme(addr)
	host, port := "", ""
	if hostPort != "" {
		var err error
		host, port, err = net.SplitHostPort(hostPort)
		if err != nil {
			return "", "", "", errors.Wrapf(err, "splitting host port: %s", hostPort)
		}
	}
	// It's not ideal to have a default here, but the alterative
	// results in a port of 0, which causes Pilosa to listen on
	// a random port.
	if port == "" {
		port = "10101"
	}
	return scheme, host, port, nil
}
351900
func LookupIPv6(ipv6 string) *endpoint.Endpoint {
	mutex.RLock()
	ep := lookupIPv6(ipv6)
	mutex.RUnlock()
	return ep
}
163836
func getFirstLocalIPAddr() (net.IP, error) {
	addrs, err := net.InterfaceAddrs()
	if err != nil {
		return nil, err
	}

	for _, addr := range addrs {
		var ip net.IP
		switch v := addr.(type) {
		case *net.IPNet:
			ip = v.IP
		case *net.IPAddr:
			ip = v.IP
		}
		if ip == nil || ip.IsLoopback() || ip.IsUnspecified() {
			continue
		}
		ip = ip.To4()
		if ip == nil {
			continue // not an ipv4 address
		}
		return ip, nil
	}

	return nil, errors.New("Could not determine ip address")
}
1021456
func lookupHost(hostname string) (string, error) {
	addrs, err := net.LookupHost(hostname)

	if err != nil {
		return "", err
	}
	return addrs[0], nil
}
951530
func (sl *ServerLookup) ServerAddr(id raft.ServerID) (raft.ServerAddress, error) {
	sl.lock.RLock()
	defer sl.lock.RUnlock()
	svr, ok := sl.idToServer[id]
	if !ok {
		return "", fmt.Errorf("Could not find address for server id %v", id)
	}
	return raft.ServerAddress(svr.Addr.String()), nil
}
443540
func (c *Client) serverNameOfAddr(addr string) string {
	serverName, _, err := net.SplitHostPort(addr)
	if err != nil {
		c.printf("could not get server name from address %q: %v", addr, err)
		return ""
	}
	if ip := net.ParseIP(serverName); ip != nil {
		return ""
	}
	return serverName
}
550390
func CanonicalAddr(url *url.URL) string {
	addr := url.Host
	if !hasPort(addr) {
		return addr + ":" + portMap[url.Scheme]
	}
	return addr
}