// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package nettest provides utilities for network testing.
package nettest
import (
"errors"
"fmt"
"io/ioutil"
"net"
"os"
"os/exec"
"runtime"
"strconv"
"strings"
"sync"
"time"
)
var (
stackOnce sync.Once
ipv4Enabled bool
ipv6Enabled bool
rawSocketSess bool
aixTechLvl int
aLongTimeAgo = time.Unix(233431200, 0)
neverTimeout = time.Time{}
errNoAvailableInterface = errors.New("no available interface")
errNoAvailableAddress = errors.New("no available address")
)
func probeStack() {
if ln, err := net.Listen("tcp4", "127.0.0.1:0"); err == nil {
ln.Close()
ipv4Enabled = true
}
if ln, err := net.Listen("tcp6", "[::1]:0"); err == nil {
ln.Close()
ipv6Enabled = true
}
rawSocketSess = supportsRawSocket()
if runtime.GOOS == "aix" {
out, err := exec.Command("oslevel", "-s").Output()
if err == nil {
aixTechLvl, _ = strconv.Atoi(string(out[5:7]))
}
}
}
func aixTechLevel() int {
stackOnce.Do(probeStack)
return aixTechLvl
}
// SupportsIPv4 reports whether the platform supports IPv4 networking
// functionality.
func SupportsIPv4() bool {
stackOnce.Do(probeStack)
return ipv4Enabled
}
// SupportsIPv6 reports whether the platform supports IPv6 networking
// functionality.
func SupportsIPv6() bool {
stackOnce.Do(probeStack)
return ipv6Enabled
}
// SupportsRawSocket reports whether the current session is available
// to use raw sockets.
func SupportsRawSocket() bool {
stackOnce.Do(probeStack)
return rawSocketSess
}
// TestableNetwork reports whether network is testable on the current
// platform configuration.
//
// See func Dial of the standard library for the supported networks.
func TestableNetwork(network string) bool {
ss := strings.Split(network, ":")
switch ss[0] {
case "ip+nopriv":
// This is an internal network name for testing on the
// package net of the standard library.
switch runtime.GOOS {
case "android", "fuchsia", "hurd", "js", "nacl", "plan9", "windows":
return false
case "darwin":
// iOS doesn't support it.
if runtime.GOARCH == "arm" || runtime.GOARCH == "arm64" {
return false
}
}
case "ip", "ip4", "ip6":
switch runtime.GOOS {
case "fuchsia", "hurd", "js", "nacl", "plan9":
return false
default:
if os.Getuid() != 0 {
return false
}
}
case "unix", "unixgram":
switch runtime.GOOS {
case "android", "fuchsia", "hurd", "js", "nacl", "plan9", "windows":
return false
case "aix":
// Unix network isn't properly working on AIX
// 7.2 with Technical Level < 2.
if aixTechLevel() < 2 {
return false
}
return true
case "darwin":
// iOS does not support unix, unixgram.
if runtime.GOARCH == "arm" || runtime.GOARCH == "arm64" {
return false
}
}
case "unixpacket":
switch runtime.GOOS {
case "aix", "android", "fuchsia", "hurd", "darwin", "js", "nacl", "plan9", "windows":
return false
case "netbsd":
// It passes on amd64 at least. 386 fails
// (Issue 22927). arm is unknown.
if runtime.GOARCH == "386" {
return false
}
}
}
switch ss[0] {
case "tcp4", "udp4", "ip4":
return SupportsIPv4()
case "tcp6", "udp6", "ip6":
return SupportsIPv6()
}
return true
}
// TestableAddress reports whether address of network is testable on
// the current platform configuration.
func TestableAddress(network, address string) bool {
switch ss := strings.Split(network, ":"); ss[0] {
case "unix", "unixgram", "unixpacket":
// Abstract unix domain sockets, a Linux-ism.
if address[0] == '@' && runtime.GOOS != "linux" {
return false
}
}
return true
}
// NewLocalListener returns a listener which listens to a loopback IP
// address or local file system path.
//
// The provided network must be "tcp", "tcp4", "tcp6", "unix" or
// "unixpacket".
func NewLocalListener(network string) (net.Listener, error) {
switch network {
case "tcp":
if SupportsIPv4() {
if ln, err := net.Listen("tcp4", "127.0.0.1:0"); err == nil {
return ln, nil
}
}
if SupportsIPv6() {
return net.Listen("tcp6", "[::1]:0")
}
case "tcp4":
if SupportsIPv4() {
return net.Listen("tcp4", "127.0.0.1:0")
}
case "tcp6":
if SupportsIPv6() {
return net.Listen("tcp6", "[::1]:0")
}
case "unix", "unixpacket":
path, err := LocalPath()
if err != nil {
return nil, err
}
return net.Listen(network, path)
}
return nil, fmt.Errorf("%s is not supported on %s/%s", network, runtime.GOOS, runtime.GOARCH)
}
// NewLocalPacketListener returns a packet listener which listens to a
// loopback IP address or local file system path.
//
// The provided network must be "udp", "udp4", "udp6" or "unixgram".
func NewLocalPacketListener(network string) (net.PacketConn, error) {
switch network {
case "udp":
if SupportsIPv4() {
if c, err := net.ListenPacket("udp4", "127.0.0.1:0"); err == nil {
return c, nil
}
}
if SupportsIPv6() {
return net.ListenPacket("udp6", "[::1]:0")
}
case "udp4":
if SupportsIPv4() {
return net.ListenPacket("udp4", "127.0.0.1:0")
}
case "udp6":
if SupportsIPv6() {
return net.ListenPacket("udp6", "[::1]:0")
}
case "unixgram":
path, err := LocalPath()
if err != nil {
return nil, err
}
return net.ListenPacket(network, path)
}
return nil, fmt.Errorf("%s is not supported on %s/%s", network, runtime.GOOS, runtime.GOARCH)
}
// LocalPath returns a local path that can be used for Unix-domain
// protocol testing.
func LocalPath() (string, error) {
f, err := ioutil.TempFile("", "go-nettest")
if err != nil {
return "", err
}
path := f.Name()
f.Close()
os.Remove(path)
return path, nil
}
// MulticastSource returns a unicast IP address on ifi when ifi is an
// IP multicast-capable network interface.
//
// The provided network must be "ip", "ip4" or "ip6".
func MulticastSource(network string, ifi *net.Interface) (net.IP, error) {
switch network {
case "ip", "ip4", "ip6":
default:
return nil, errNoAvailableAddress
}
if ifi == nil || ifi.Flags&net.FlagUp == 0 || ifi.Flags&net.FlagMulticast == 0 {
return nil, errNoAvailableAddress
}
ip, ok := hasRoutableIP(network, ifi)
if !ok {
return nil, errNoAvailableAddress
}
return ip, nil
}
// LoopbackInterface returns an available logical network interface
// for loopback test.
func LoopbackInterface() (*net.Interface, error) {
ift, err := net.Interfaces()
if err != nil {
return nil, errNoAvailableInterface
}
for _, ifi := range ift {
if ifi.Flags&net.FlagLoopback != 0 && ifi.Flags&net.FlagUp != 0 {
return &ifi, nil
}
}
return nil, errNoAvailableInterface
}
// RoutedInterface returns a network interface that can route IP
// traffic and satisfies flags.
//
// The provided network must be "ip", "ip4" or "ip6".
func RoutedInterface(network string, flags net.Flags) (*net.Interface, error) {
switch network {
case "ip", "ip4", "ip6":
default:
return nil, errNoAvailableInterface
}
ift, err := net.Interfaces()
if err != nil {
return nil, errNoAvailableInterface
}
for _, ifi := range ift {
if ifi.Flags&flags != flags {
continue
}
if _, ok := hasRoutableIP(network, &ifi); !ok {
continue
}
return &ifi, nil
}
return nil, errNoAvailableInterface
}
func hasRoutableIP(network string, ifi *net.Interface) (net.IP, bool) {
ifat, err := ifi.Addrs()
if err != nil {
return nil, false
}
for _, ifa := range ifat {
switch ifa := ifa.(type) {
case *net.IPAddr:
if ip, ok := routableIP(network, ifa.IP); ok {
return ip, true
}
case *net.IPNet:
if ip, ok := routableIP(network, ifa.IP); ok {
return ip, true
}
}
}
return nil, false
}
func routableIP(network string, ip net.IP) (net.IP, bool) {
if !ip.IsLoopback() && !ip.IsLinkLocalUnicast() && !ip.IsGlobalUnicast() {
return nil, false
}
switch network {
case "ip4":
if ip := ip.To4(); ip != nil {
return ip, true
}
case "ip6":
if ip.IsLoopback() { // addressing scope of the loopback address depends on each implementation
return nil, false
}
if ip := ip.To16(); ip != nil && ip.To4() == nil {
return ip, true
}
default:
if ip := ip.To4(); ip != nil {
return ip, true
}
if ip := ip.To16(); ip != nil {
return ip, true
}
}
return nil, false
}
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