TUN inbound: Don't set IP_BOUND_IF on IPv6 sockets on Darwin

Since #7173, a failed interface binding fails the dial. On Darwin (macOS
and iOS), setinterface fell through from IPV6_BOUND_IF to IP_BOUND_IF on
IPv6 sockets, which Darwin rejects with EINVAL. So every UDP dial failed,
as Go opens a dual-stack IPv6 socket for it, and so did TCP to IPv6. TCP to
IPv4 uses an IPv4 socket and kept working. Before #7173 the error was only
logged.

IPV6_BOUND_IF binds the whole socket, so on a dual-stack socket it covers
its IPv4 traffic as well. Set only the option of the socket's family, as
sockopt_darwin.go already does for sockopt.interface. The new test binds
each kind of socket to lo0.

Linux, Android and FreeBSD bind with socket-level options (SO_BINDTODEVICE,
SO_SETFIB) that don't depend on the IP version. On Windows, the related case
of an adapter without IPv4 or IPv6 is handled in #7214.

Fixes #7228

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

common/lua/program.go

@@ -11,7 +11,7 @@ import (
 
 	"github.com/xtls/xray-core/common/base64"
 	"github.com/xtls/xray-core/common/errors"
-	"github.com/xtls/xray-core/common/platform/filesystem"
+	"github.com/xtls/xray-core/common/platform"
 	glua "github.com/yuin/gopher-lua"
 	"github.com/yuin/gopher-lua/parse"
 )
@@ -36,7 +36,7 @@ func Compile(script string) (*Program, error) {
 		// TODO: Restore inline script support and re-enable the related tests.
 		return nil, errors.New("currently unavailable")
 		code, err = base64.Decode(script)
-	} else if name, err = filesystem.ResolveLuaFile(script); err == nil {
+	} else if name, err = platform.ResolveLuaFile(script); err == nil {
 		code, err = os.ReadFile(name)
 		// TODO: Restore privileged signature authorization and re-enable the related tests and CLI entries.
 		// if err == nil {

common/lua/program_test.go

@@ -187,20 +187,19 @@ func TestCompileInlineDiagnostics(t *testing.T) {
 */
 
 func TestCompileFileExtension(t *testing.T) {
-	for _, name := range []string{"script", "script.dat", "script.lua.txt"} {
-		if program, err := Compile(name); program != nil || err == nil || !strings.Contains(err.Error(), "Lua file extension must be .lua") {
-			t.Fatalf("Compile(%q) = %v, %v; want nil program and .lua extension error", name, program, err)
-		}
-	}
-	for _, name := range []string{"script.lua", "script.LUA", "script.Lua", "script.lUa"} {
+	for _, name := range []string{"script", "script.dat", "script.lua.txt", "script.LUA"} {
 		path := filepath.Join(t.TempDir(), name)
 		if err := os.WriteFile(path, []byte("value = 42"), 0o600); err != nil {
 			t.Fatal(err)
 		}
-		if program, err := Compile(path); program == nil || err != nil {
-			t.Fatalf("Compile(%q) = %v, %v; want successful compilation", path, program, err)
+		if program, err := Compile(path); program != nil || err == nil || !strings.Contains(err.Error(), "Lua file extension must be .lua") {
+			t.Fatalf("Compile(%q) = %v, %v; want nil program and .lua extension error", path, program, err)
 		}
 	}
+	path := writeTestScript(t, "value = 42") + string(filepath.Separator) + "."
+	if program, err := Compile(path); program == nil || err != nil {
+		t.Fatalf("Compile(%q) = %v, %v; want acceptance of the resolved .lua path", path, program, err)
+	}
 }
 
 func TestCompileRejectsReadFailure(t *testing.T) {
@@ -235,6 +234,10 @@ func writeTestScript(t *testing.T, code string) string {
 	if err := os.WriteFile(path, []byte(code), 0o600); err != nil {
 		t.Fatal(err)
 	}
+	path, err := filepath.EvalSymlinks(path)
+	if err != nil {
+		t.Fatal(err)
+	}
 	return path
 }
 

common/platform/filesystem/file.go

@@ -5,7 +5,6 @@ import (
 	"io"
 	"os"
 	"path/filepath"
-	"strings"
 
 	"github.com/xtls/xray-core/common/buf"
 	"github.com/xtls/xray-core/common/platform"
@@ -27,6 +26,14 @@ func ReadFile(path string) ([]byte, error) {
 	return buf.ReadAllToBytes(reader)
 }
 
+func ReadAsset(file string) ([]byte, error) {
+	path, _, err := getAssetFileLocation(file)
+	if err != nil {
+		return nil, err
+	}
+	return ReadFile(path)
+}
+
 func OpenAsset(file string) (io.ReadCloser, int64, error) {
 	path, info, err := getAssetFileLocation(file)
 	if err != nil {
@@ -36,6 +43,11 @@ func OpenAsset(file string) (io.ReadCloser, int64, error) {
 	return r, info.Size(), err
 }
 
+func StatAsset(file string) (os.FileInfo, error) {
+	_, info, err := getAssetFileLocation(file)
+	return info, err
+}
+
 func ResolveAsset(file string) (string, error) {
 	path, _, err := getAssetFileLocation(file)
 	return path, err
@@ -67,29 +79,17 @@ func ReadCert(file string) ([]byte, error) {
 	return ReadFile(platform.GetCertLocation(file))
 }
 
-// ResolveLuaFile finds a local .lua script and returns its absolute path.
-// Relative paths: XRAY_LOCATION_CONFDIR > XRAY_LOCATION_CONFIG > working dir > executable dir.
-func ResolveLuaFile(path string) (string, error) {
-	if !strings.EqualFold(filepath.Ext(path), ".lua") {
-		return "", errors.New("Lua file extension must be .lua")
+func CopyFile(dst string, src string) error {
+	bytes, err := ReadFile(src)
+	if err != nil {
+		return err
 	}
-	if filepath.IsAbs(path) {
-		return path, nil
+	f, err := os.OpenFile(dst, os.O_CREATE|os.O_WRONLY, 0o644)
+	if err != nil {
+		return err
 	}
-	for _, dir := range []string{
-		platform.GetConfDirPath(),
-		platform.NewEnvFlag(platform.ConfigLocation).GetValue(func() string { return "" }),
-		".",
-		platform.GetExecutableDir(),
-	} {
-		if dir != "" {
-			resolved := filepath.Join(dir, path)
-			if _, err := os.Stat(resolved); err == nil {
-				return filepath.Abs(resolved)
-			} else if !os.IsNotExist(err) {
-				return "", err
-			}
-		}
-	}
-	return "", os.ErrNotExist
+	defer f.Close()
+
+	_, err = f.Write(bytes)
+	return err
 }

common/platform/filesystem/file_test.go

@@ -1,17 +1,13 @@
 package filesystem_test
 
 import (
-	"errors"
-	"os"
 	"path/filepath"
 	"testing"
 
-	"github.com/xtls/xray-core/common"
-	"github.com/xtls/xray-core/common/platform"
 	. "github.com/xtls/xray-core/common/platform/filesystem"
 )
 
-func TestResolveAssetRejectsInvalidPath(t *testing.T) {
+func TestStatAssetRejectsInvalidPath(t *testing.T) {
 	for _, file := range []string{
 		"",
 		".",
@@ -29,49 +25,8 @@ func TestResolveAssetRejectsInvalidPath(t *testing.T) {
 		`nested\..\geoip.dat`,
 		filepath.Join(t.TempDir(), "geoip.dat"),
 	} {
-		if _, err := ResolveAsset(file); err == nil {
+		if _, err := StatAsset(file); err == nil {
 			t.Fatalf("expected error for %q", file)
 		}
 	}
 }
-
-func TestResolveLuaFile(t *testing.T) {
-	t.Chdir(t.TempDir())
-	workingDir, err := os.Getwd()
-	common.Must(err)
-	executable, err := os.Executable()
-	common.Must(err)
-	file, err := os.CreateTemp(filepath.Dir(executable), "lua-*.lua")
-	common.Must(err)
-	common.Must(file.Close())
-	defer os.Remove(file.Name())
-
-	name := filepath.Base(file.Name())
-	paths := []string{
-		filepath.Join(t.TempDir(), name),
-		filepath.Join(t.TempDir(), name),
-		filepath.Join(workingDir, name),
-		file.Name(),
-	}
-	t.Setenv(platform.ConfdirLocation, filepath.Dir(paths[0]))
-	t.Setenv(platform.ConfigLocation, filepath.Dir(paths[1]))
-	for _, path := range paths[:3] {
-		common.Must(os.WriteFile(path, nil, 0o600))
-	}
-	if got, err := ResolveLuaFile(paths[2]); err != nil || got != paths[2] {
-		t.Fatalf("absolute path = %q, %v; want %q", got, err, paths[2])
-	}
-	for i, want := range paths {
-		if i == 2 {
-			t.Setenv(platform.ConfdirLocation, "")
-			t.Setenv(platform.ConfigLocation, "")
-		}
-		if got, err := ResolveLuaFile(name); err != nil || got != want {
-			t.Fatalf("resolved path = %q, %v; want %q", got, err, want)
-		}
-		common.Must(os.Remove(want))
-	}
-	if _, err := ResolveLuaFile(name); !errors.Is(err, os.ErrNotExist) {
-		t.Fatalf("missing file error = %v", err)
-	}
-}

common/platform/others.go

@@ -14,7 +14,7 @@ func LineSeparator() string {
 
 // GetAssetLocation searches for `file` in the env dir, the executable dir, and certain locations
 func GetAssetLocation(file string) string {
-	assetPath := NewEnvFlag(AssetLocation).GetValue(GetExecutableDir)
+	assetPath := NewEnvFlag(AssetLocation).GetValue(getExecutableDir)
 	defPath := filepath.Join(assetPath, file)
 	for _, p := range []string{
 		defPath,
@@ -36,6 +36,6 @@ func GetAssetLocation(file string) string {
 
 // GetCertLocation searches for `file` in the env dir and the executable dir
 func GetCertLocation(file string) string {
-	certPath := NewEnvFlag(CertLocation).GetValue(GetExecutableDir)
+	certPath := NewEnvFlag(CertLocation).GetValue(getExecutableDir)
 	return filepath.Join(certPath, file)
 }

common/platform/platform.go

@@ -1,6 +1,8 @@
 package platform // import "github.com/xtls/xray-core/common/platform"
 
 import (
+	"errors"
+	"fmt"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -72,7 +74,7 @@ func NormalizeEnvName(name string) string {
 	return strings.ReplaceAll(strings.ToUpper(strings.TrimSpace(name)), ".", "_")
 }
 
-func GetExecutableDir() string {
+func getExecutableDir() string {
 	exec, err := os.Executable()
 	if err != nil {
 		return ""
@@ -81,7 +83,7 @@ func GetExecutableDir() string {
 }
 
 func GetConfigurationPath() string {
-	configPath := NewEnvFlag(ConfigLocation).GetValue(GetExecutableDir)
+	configPath := NewEnvFlag(ConfigLocation).GetValue(getExecutableDir)
 	return filepath.Join(configPath, "config.json")
 }
 
@@ -90,3 +92,64 @@ func GetConfDirPath() string {
 	configPath := NewEnvFlag(ConfdirLocation).GetValue(func() string { return "" })
 	return configPath
 }
+
+// ResolveLuaFile finds a local .lua script and returns its resolved absolute path.
+// Relative paths: XRAY_LOCATION_CONFDIR > XRAY_LOCATION_CONFIG > working dir > executable dir.
+func ResolveLuaFile(path string) (string, error) {
+	if path == "" {
+		return "", errors.New("Lua file path is empty")
+	}
+	paths := []string{path}
+	if !filepath.IsAbs(path) {
+		paths = nil
+		for _, dir := range []string{
+			GetConfDirPath(),
+			NewEnvFlag(ConfigLocation).GetValue(func() string { return "" }),
+			".",
+			getExecutableDir(),
+		} {
+			if dir != "" {
+				paths = append(paths, filepath.Join(dir, path))
+			}
+		}
+	}
+	path, err := resolveFile(paths)
+	if err != nil {
+		return "", err
+	}
+	return resolveLuaTarget(path)
+}
+
+func resolveLuaTarget(path string) (string, error) {
+	path, err := filepath.EvalSymlinks(path)
+	if err != nil {
+		return "", fmt.Errorf("failed to resolve Lua file symlinks: %w", err)
+	}
+	if filepath.Ext(path) != ".lua" {
+		return "", errors.New("Lua file extension must be .lua")
+	}
+	return path, nil
+}
+
+func resolveFile(paths []string) (string, error) {
+	var tried []string
+	for _, path := range paths {
+		path, err := filepath.Abs(path)
+		if err != nil {
+			return "", fmt.Errorf("failed to resolve file path: %w", err)
+		}
+		tried = append(tried, path)
+		info, err := os.Stat(path)
+		if errors.Is(err, os.ErrNotExist) {
+			continue
+		}
+		if err != nil {
+			return "", fmt.Errorf("failed to inspect file %q: %w", path, err)
+		}
+		if !info.Mode().IsRegular() {
+			return "", fmt.Errorf("file is not a regular file: %s", path)
+		}
+		return path, nil
+	}
+	return "", fmt.Errorf("file not found; tried %q: %w", tried, os.ErrNotExist)
+}

common/platform/platform_test.go

@@ -1,9 +1,11 @@
 package platform_test
 
 import (
+	"errors"
 	"os"
 	"path/filepath"
 	"runtime"
+	"strings"
 	"testing"
 
 	"github.com/xtls/xray-core/common"
@@ -64,3 +66,89 @@ func TestGetAssetLocation(t *testing.T) {
 		}
 	}
 }
+
+func TestResolveLuaFile(t *testing.T) {
+	workingDir := t.TempDir()
+	t.Chdir(workingDir)
+	executable, err := os.Executable()
+	common.Must(err)
+	file, err := os.CreateTemp(filepath.Dir(executable), "lua-*.lua")
+	common.Must(err)
+	common.Must(file.Close())
+	defer os.Remove(file.Name())
+
+	name := filepath.Base(file.Name())
+	paths := []string{
+		filepath.Join(t.TempDir(), name),
+		filepath.Join(t.TempDir(), name),
+		filepath.Join(workingDir, name),
+		file.Name(),
+	}
+	t.Setenv(ConfdirLocation, filepath.Dir(paths[0]))
+	t.Setenv(ConfigLocation, filepath.Dir(paths[1]))
+	for _, path := range paths[:3] {
+		common.Must(os.WriteFile(path, nil, 0o600))
+	}
+	for i, path := range paths {
+		paths[i], err = filepath.EvalSymlinks(path)
+		common.Must(err)
+	}
+	if got, err := ResolveLuaFile(paths[2]); err != nil || got != paths[2] {
+		t.Fatalf("absolute path = %q, %v; want %q", got, err, paths[2])
+	}
+	for i, want := range paths {
+		if i == 2 {
+			t.Setenv(ConfdirLocation, "")
+			t.Setenv(ConfigLocation, "")
+		}
+		if got, err := ResolveLuaFile(name); err != nil || got != want {
+			t.Fatalf("resolved path = %q, %v; want %q", got, err, want)
+		}
+		common.Must(os.Remove(want))
+	}
+	if _, err := ResolveLuaFile(name); !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("missing file error = %v", err)
+	}
+
+	t.Setenv(ConfdirLocation, filepath.Dir(paths[0]))
+	t.Setenv(ConfigLocation, filepath.Dir(paths[1]))
+	common.Must(os.Mkdir(paths[0], 0o700))
+	common.Must(os.WriteFile(paths[1], nil, 0o600))
+	for _, path := range []string{"", name, filepath.Join(t.TempDir(), name)} {
+		if _, err := ResolveLuaFile(path); err == nil {
+			t.Fatalf("accepted invalid path %q", path)
+		}
+	}
+}
+
+func TestResolveLuaFileSymlink(t *testing.T) {
+	for _, tc := range []struct {
+		link, target string
+		valid        bool
+	}{
+		{"alias.lua", "data.dat", false},
+		{"alias.dat", "script.lua", true},
+	} {
+		t.Run(tc.link, func(t *testing.T) {
+			dir, err := filepath.EvalSymlinks(t.TempDir())
+			common.Must(err)
+			target := filepath.Join(dir, tc.target)
+			common.Must(os.WriteFile(target, nil, 0o600))
+			link := filepath.Join(dir, tc.link)
+			if err := os.Symlink(tc.target, link); err != nil {
+				if runtime.GOOS == "windows" {
+					t.Skipf("cannot create symlinks: %v", err)
+				}
+				t.Fatal(err)
+			}
+			got, err := ResolveLuaFile(link)
+			if tc.valid {
+				if err != nil || got != target {
+					t.Fatalf("ResolveLuaFile(%q) = %q, %v; want %q", link, got, err, target)
+				}
+			} else if err == nil || got != "" || !strings.Contains(err.Error(), "Lua file extension must be .lua") {
+				t.Fatalf("ResolveLuaFile(%q) = %q, %v; want .lua extension error", link, got, err)
+			}
+		})
+	}
+}

common/platform/windows.go

@@ -11,12 +11,12 @@ func LineSeparator() string {
 
 // GetAssetLocation searches for `file` in the env dir and the executable dir
 func GetAssetLocation(file string) string {
-	assetPath := NewEnvFlag(AssetLocation).GetValue(GetExecutableDir)
+	assetPath := NewEnvFlag(AssetLocation).GetValue(getExecutableDir)
 	return filepath.Join(assetPath, file)
 }
 
 // GetCertLocation searches for `file` in the env dir and the executable dir
 func GetCertLocation(file string) string {
-	certPath := NewEnvFlag(CertLocation).GetValue(GetExecutableDir)
+	certPath := NewEnvFlag(CertLocation).GetValue(getExecutableDir)
 	return filepath.Join(certPath, file)
 }

infra/conf/geodata.go

@@ -19,7 +19,7 @@ func (c *GeodataAssetConfig) Build() (*geodata.Asset, error) {
 	if err := validateHTTPS(c.URL); err != nil {
 		return nil, errors.New("invalid geodata asset url: ", c.URL).Base(err)
 	}
-	if _, err := filesystem.ResolveAsset(c.File); err != nil {
+	if _, err := filesystem.StatAsset(c.File); err != nil {
 		return nil, errors.New("invalid geodata asset file: ", c.File).Base(err)
 	}
 	return &geodata.Asset{

main/commands/all/lua/sign.go

@@ -3,7 +3,6 @@ package lua
 import (
 	"os"
 	"path/filepath"
-	"strings"
 
 	xlua "github.com/xtls/xray-core/common/lua"
 	"github.com/xtls/xray-core/main/commands/base"
@@ -33,13 +32,14 @@ func executeSign(cmd *base.Command, args []string) {
 		cmd.Usage()
 	}
 
-	if !strings.EqualFold(filepath.Ext(args[0]), ".lua") {
-		base.Fatalf("Lua file extension must be .lua")
-	}
 	info, err := os.Stat(args[0])
 	if err != nil {
 		base.Fatalf("failed to inspect Lua file: %s", err)
 	}
+	if !info.Mode().IsRegular() {
+		base.Fatalf("Lua input is not a regular file: %s", args[0])
+	}
+
 	code, err := os.ReadFile(args[0])
 	if err != nil {
 		base.Fatalf("failed to read Lua file: %s", err)
@@ -67,7 +67,14 @@ func executeSign(cmd *base.Command, args []string) {
 
 func writeSignedFile(path string, code []byte, mode os.FileMode) error {
 	if info, err := os.Stat(path); err == nil {
+		if !info.Mode().IsRegular() {
+			return &os.PathError{Op: "write", Path: path, Err: os.ErrInvalid}
+		}
 		mode = info.Mode().Perm()
+		path, err = filepath.EvalSymlinks(path)
+		if err != nil {
+			return err
+		}
 	} else if !os.IsNotExist(err) {
 		return err
 	}

main/confloader/external/external.go

@@ -58,10 +58,18 @@ func readConfigFile(file *os.File) ([]byte, error) {
 		return nil, err
 	}
 	if info.Mode().IsRegular() {
-		switch strings.ToLower(filepath.Ext(file.Name())) {
+		path, err := filepath.Abs(file.Name())
+		if err != nil {
+			return nil, err
+		}
+		path, err = filepath.EvalSymlinks(path)
+		if err != nil {
+			return nil, err
+		}
+		switch strings.ToLower(filepath.Ext(path)) {
 		case ".jsonc", ".json", ".yml", ".yaml", ".toml", ".pb", ".protobuf":
 		default:
-			return nil, errors.New("unsupported config file extension: ", file.Name())
+			return nil, errors.New("unsupported config file extension: ", path)
 		}
 	}
 	return io.ReadAll(file)

proxy/tun/tun_darwin.go

@@ -558,19 +558,16 @@ func ioctlPtr(fd int, req uint, arg unsafe.Pointer) error {
 }
 
 func setinterface(network, address string, fd uintptr, iface *net.Interface) error {
-	var err1, err2 error
-
 	switch network {
 	case "tcp6", "udp6", "ip6":
-		err1 = unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_BOUND_IF, iface.Index)
-		fallthrough
+		// IPV6_BOUND_IF binds the IPv4 traffic of a dual-stack socket as
+		// well, and an IPv6 socket rejects IP_BOUND_IF with EINVAL.
+		return unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_BOUND_IF, iface.Index)
 	case "tcp4", "udp4", "ip4":
-		err2 = unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_BOUND_IF, iface.Index)
+		return unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_BOUND_IF, iface.Index)
 	default:
 		panic(network + " " + address)
 	}
-
-	return errors.Join(err1, err2)
 }
 
 func findOutboundInterface(tunIndex int, fixedName string) (*net.Interface, error) {

proxy/tun/tun_darwin_test.go

@@ -3,7 +3,10 @@
 package tun
 
 import (
+	"context"
+	"net"
 	"sync"
+	"syscall"
 	"testing"
 	"time"
 
@@ -231,3 +234,40 @@ func TestWaitKqueueReportsPersistentFailure(t *testing.T) {
 		}
 	}
 }
+
+// TestSetinterfaceSocketFamilies binds each kind of socket Xray's dialers
+// open to lo0, including the dual-stack one Go opens for UDP.
+func TestSetinterfaceSocketFamilies(t *testing.T) {
+	lo, err := net.InterfaceByName("lo0")
+	if err != nil {
+		t.Skip(err)
+	}
+	lc := net.ListenConfig{Control: func(network, address string, c syscall.RawConn) error {
+		var err error
+		if controlErr := c.Control(func(fd uintptr) {
+			err = setinterface(network, address, fd, lo)
+		}); controlErr != nil {
+			return controlErr
+		}
+		return err
+	}}
+	for _, s := range []struct{ network, address string }{
+		{"udp", "0.0.0.0:0"}, // dual-stack
+		{"udp4", "127.0.0.1:0"},
+		{"udp6", "[::1]:0"},
+		{"tcp4", "127.0.0.1:0"},
+		{"tcp6", "[::1]:0"},
+	} {
+		var closer interface{ Close() error }
+		if s.network[:3] == "udp" {
+			closer, err = lc.ListenPacket(context.Background(), s.network, s.address)
+		} else {
+			closer, err = lc.Listen(context.Background(), s.network, s.address)
+		}
+		if err != nil {
+			t.Errorf("%s %s: %v", s.network, s.address, err)
+			continue
+		}
+		closer.Close()
+	}
+}