network = "ip"
	}
	afnet, _, err := parseNetwork(context.Background(), network, false)
	if err != nil {
		return nil, err
	}
	switch afnet {
	case "ip", "ip4", "ip6":
	default:
		return nil, UnknownNetworkError(network)
	}
	addrs, err := DefaultResolver.internetAddrList(context.Background(), afnet, address)
	if err != nil {
		return nil, err
	}
	return addrs.forResolve(network, address).(*IPAddr), nil
}

	var sotype int
	switch net {
	case "unix":
		sotype = syscall.SOCK_STREAM
	case "unixgram":
		sotype = syscall.SOCK_DGRAM
	case "unixpacket":
		sotype = syscall.SOCK_SEQPACKET
	default:
		return nil, UnknownNetworkError(net)
	}

	switch mode {
	case "dial":
		if laddr != nil && laddr.isWildcard() {
			laddr = nil
		}
		if raddr != nil && raddr.isWildcard() {
			raddr = nil
		}

		switch network {
		case "tcp", "tcp4", "tcp6":
		case "udp", "udp4", "udp6":
		case "ip", "ip4", "ip6":
			if needsProto {
				return "", 0, UnknownNetworkError(network)
			}
		case "unix", "unixgram", "unixpacket":
		default:
			return "", 0, UnknownNetworkError(network)
		}
		return network, 0, nil
	}
	afnet = network[:i]
	switch afnet {
	case "ip", "ip4", "ip6":
		protostr := network[i+1:]

second:
	if isPlatformError(nestedErr) {
		return nil
	}
	switch err := nestedErr.(type) {
	case *AddrError, *timeoutError, *DNSError, InvalidAddrError, *ParseError, *poll.DeadlineExceededError, UnknownNetworkError:
		return nil
	case interface{ isAddrinfoErrno() }:
		return nil
	case *os.SyscallError:
		nestedErr = err.Err
		goto third
	case *fs.PathError: // for Plan 9
		nestedErr = err.Err
		goto third

			}
			if portnum, err = r.LookupPort(ctx, net, port); err != nil {
				return nil, err
			}
		}
	case "ip", "ip4", "ip6":
		if addr != "" {
			host = addr
		}
	default:
		return nil, UnknownNetworkError(net)
	}
	inetaddr := func(ip IPAddr) Addr {
		switch net {
		case "tcp", "tcp4", "tcp6":
			return &TCPAddr{IP: ip.IP, Port: portnum, Zone: ip.Zone}
		case "udp", "udp4", "udp6":

	}
}

// The various errors should implement the Error interface.
func TestErrors(t *testing.T) {
	var (
		_ Error = &OpError{}
		_ Error = &ParseError{}
		_ Error = &AddrError{}
		_ Error = UnknownNetworkError("")
		_ Error = InvalidAddrError("")
		_ Error = &timeoutError{}
		_ Error = &DNSConfigError{}
		_ Error = &DNSError{}
	)

	// ErrClosed was introduced as type error, so we can't check

	{"", "[::1]:0", &UDPAddr{IP: ParseIP("::1"), Port: 0}, nil},         // Go 1.0 behavior

	{"udp", ":12345", &UDPAddr{Port: 12345}, nil},

	{"http", "127.0.0.1:0", nil, UnknownNetworkError("http")},

	{"udp", "127.0.0.1:domain", &UDPAddr{IP: ParseIP("127.0.0.1"), Port: 53}, nil},
	{"udp", "[::ffff:127.0.0.1]:domain", &UDPAddr{IP: ParseIP("::ffff:127.0.0.1"), Port: 53}, nil},

	{"", "[::1]:0", &TCPAddr{IP: ParseIP("::1"), Port: 0}, nil},         // Go 1.0 behavior

	{"tcp", ":12345", &TCPAddr{Port: 12345}, nil},

	{"http", "127.0.0.1:0", nil, UnknownNetworkError("http")},

	{"tcp", "127.0.0.1:http", &TCPAddr{IP: ParseIP("127.0.0.1"), Port: 80}, nil},
	{"tcp", "[::ffff:127.0.0.1]:http", &TCPAddr{IP: ParseIP("::ffff:127.0.0.1"), Port: 80}, nil},

	afnet, _, err := parseNetwork(ctx, network, false)
	if err != nil {
		return nil, err
	}
	switch afnet {
	case "ip", "ip4", "ip6":
	default:
		return nil, UnknownNetworkError(network)
	}

	if host == "" {
		return nil, newDNSError(errNoSuchHost, host, "")
	}
	addrs, err := r.internetAddrList(ctx, afnet, host)
	if err != nil {
		return nil, err
	}

		{"(InvalidAddrError).Error", Method, 0},
		{"(InvalidAddrError).Temporary", Method, 0},
		{"(InvalidAddrError).Timeout", Method, 0},
		{"(UnknownNetworkError).Error", Method, 0},
		{"(UnknownNetworkError).Temporary", Method, 0},
		{"(UnknownNetworkError).Timeout", Method, 0},
		{"Addr", Type, 0},
		{"AddrError", Type, 0},
		{"AddrError.Addr", Field, 0},
		{"AddrError.Err", Field, 0},